physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iv. no. 1-4. pp. 23-28 geomorphological and stratigraphic analyses at the archaeological excavation in the megapark, nyíregyháza-oros buró, b. 1 – jakab, a. 2 – lóki, j. 1 1 department of physical geography and geoinformatics, university of debrecen 2 jósa andrás museum, nyíregyháza abstract the aim of our morphological and stratigraphic investigations at the archaeological excavation in the area of the megapark at nyíregyháza– oros is to make the reconstruction of the aeolian development of the study area more accurate. the excavation is located between the remnants of two abandoned river beds in a wind-blown sand area near the crossing of main roads 4 and 41 east of nyíregyháza–oros. eight boreholes were drilled in the site of the excavation. the cores were sampled in order to perform the sedimentological analysis of the penetrated strata. strata of the sand dune are divided by a fossil soil horizon in which a cemetery from the age of the hungarian conquest was found. underneath the cemetery findings from the imperial age and urn graves from the bronze age were excavated. this suggests that wind-blown sand covered the soil horizon in a thickness of 1-1.5 m by the age of the conquest. the 3-4 m thick wind-blown sand excavated from the findings indicates sand accumulation following the 10th century. keywords: geomorphology, archaeological excavation, stratigraphic and sedimentological analyses introduction studying the development of wind-blown sand areas in hungary dates back to a century, however, accurate determination of the age of wind-blown sand formation by methods such as 14 c, osl, archaeology has become possible only recently. (kiss et al. 2006, nyári et al. 2006). the formation of the nyírség was outlined first in the publication of nagy j. (1908) and then in that of cholnoky j. (1910), however, a still accepted explanation for the development of the nyírség was presented by sümeghy j. (1944) who, based on the geological data of boreholes figured out that the nyírség is the alluvial fan of rivers arriving from the carpathians. wind-blown sand was produced from the fluvial sediments deposited by the rivers. borsy z. in his book on the nyírség (1961) dates the formation of the dunes to the dry boreal period (9000-7500 years) of the holocene. by the 1980s fossil soils found in wind-blown sand could be dated by radiocarbon analyses (borsy et al. 1981, lóki et al.1993), which revealed that the first significant sand movements in the nyírség took place in the upper plenniglacial period of the late glacial (26000-20000 years bp). in the subsequent wet period the vegetation protected the surface until the next drier period of the dryas (1300011000 years bp) when wind became the dominant land forming process again. based on the field studies of the last decade, the aeolian transformation of the land was not completed in the nyírség at the end of the pleistocene (kiss 2000, lóki 2006, lóki et al. 2008). wetter and drier periods alternated in the holocene as well and where vegetation was not protecting the surface wind was able to move the wind-blown sand deposited earlier. at present the surface forming activity of wind can be detected primarily in spring at the beginning of the growing season, however, it can be observed occasionally in winter as well (lóki 1985). detection of these “young” sand movements is helped greatly by archaeological excavations as findings (lóki – schweitzer 2001) and osl age data (nyári et al. 2006) make the age of land transformation more accurate. the aim of the morphological and stratigraphic research performed in the area of the megapark in nyíregyháza-oros was to contribute to the accurate reconstruction of the aeolian land development of the study area based on the age of the various archaeological findings and the data of sedimentological analyses. morphological conditions in the surroundings of the excavation in this part of the nyírség at the time of the accumulation of the alluvial fan the land was formed by the ancient tapoly-ondava and the laborc rivers arriving from the north until the middle of the upper plenniglacial (borsy 1961). at this time the bereg-szatmár plain and the bodrogköz started to subside and as this subsidence was somewhat stronger at the northern part and the tisza left the ér valley at around 20000-22000 years ago and passed the huszt gate and going round the beregovo mountains turned to the nw towards the bodrogköz. simultaneously with the subsidence of the marginal areas the central part of the nyírség uplifted and a dividing line developed along the hajdúhadház–nyírbátor– vásárosnamény line. turning of the tisza towards the nw resulted in that the rivers arriving from the n were unable to reach the nyírség. during the cold, dry climate of the upper plenniglacial only sparse steppe vegetation covered the fluvial sediments on the surface (borsy 1961). this vegetation was unable to provide sufficient protection against strong 24 buró, b. – jakab, a. – lóki, j. joeg vi/1-4 winds thus wind-blown sand landforms started to develop. during the transformation of the land wind filled the abandoned river channels by sand at several places. this explains that sections of different length of abandoned river beds can be observed in the nyírség today. the archaeological excavation at the junction of routes 4 and 41 east of nyíregyháza–oros lies between two river channel remnants (fig. 2). maps of the second military survey (fig. 3) indicate a sand dune elevating fig. 1 the researcher area near nyíregyháza (dot marks the study area) fig. 2 area of the excavation on a 1:10000 topographic map (former river channels are indicated by dashed lines) joeg vi/1-4 geomorphological and stratigraphic analyses at the archaeological excavation… 25 from its environment, which could provide shelter to people settling down here. fig. 3 area of the excavation on the map of the second military survey (dots mark the sites of boreholes) strata in the sand dune were divided by a fossil soil layer suggesting that the formation of the dune lasted over at least two dry periods and a wetter period between them when the soil layer was formed. thickness (50-60 cm) of the soil suggests that the wetter period lasted for several thousand years. materials and methods colleagues of the jósa andrás museum carried out detailed geodetic measurements on the original and the excavated surface prior to securing the findings. as we received access to their database the three dimension visualization of the excavated surface was possible using the software surfer (fig. 4). wind-blown sand layer was removed from the original surface down to the fossil soil layer. stratigraphic research was started on the humus containing surface between the two abandoned river beds. eight boreholes were drilled down to the groundwater table in this area (fig. 2) using a hand driller. samples were taken from the cores from each stratum in order to perform sedimentological analyses. samples were analysed in the sedimentological laboratory of the institute of earth sciences, university of debrecen. grain-size distribution, humus and caco3 content and ph of the samples were determined. grainsize distribution was determined by köhn pipette and dry sieving. caco3 content was measured by a scheibler type calcimeter. humus content was determined based on the tyurin method while ph was measured electronically. softwares microsoft excel and surfer8 were applied. fig. 4 digital elevation model the excavated surface co-ordinate system: hungarian eov (dots mark the sites of boreholes) 26 buró, b. – jakab, a. – lóki, j. joeg vi/1-4 results sedimentological results considering the composition of the samples, ratios of the coarser and finer fractions are generally small, the sand fraction dominates the grain-size distribution. particles between 0.2 and 0.02 mm are dominant in the samples (fig. 5). based on the grain-size distribution, the strata of the excavation are composed of wind-blown sand. samples are slightly and moderately calcareous and their ph measured by water and kcl dissolution is slightly basic. these data are characteristic for the nyírség. the change of humus content indicates well the buried soil layer. humus content of the upper part of the generally 60 cm thick soil layer reached 6 % and this decreases gradually downwards. humus content is around 1.3 % in the wind-blown sand below. in boreholes f1 and f8 (fig. 5) – drilled in the former beds – humus content varies between 2 and 5 % from the bottom of the borehole to the top. this can be explained by buried vegetation on the wet surface. in the 2-4 m thick excavated wind-blown sand above the fossil soil no further soil layers were found by the archaeologists. there was another thin humus layer at 120-140 cm (fig. 5). this suggests that the climate was wetter at the time of the formation of this layer, however, these conditions were short lived as subsequent wind-blown sand movement impeded the further development of the thin soil layer. fig. 5 general cross-section of the dune and the grain-size distribution of the strata and humus content of the material in the boreholes joeg vi/1-4 geomorphological and stratigraphic analyses at the archaeological excavation… 27 archaeological results archaeologists of the jósa andrás museum, nyíregyháza made preliminary excavations around nyíregyházaoros between 21 april and 6 december 2011. the area of 26 hectares was studied by the cultural heritage protection survey using excavation ditches. this revealed that practically the entire area is full of findings. more than 6000 objects were found during the 8 months of excavation. as was expected a cemetery from the age of the hungarian conquest in the 10th century was found in the north-west part of the area. this part is a sandy ridge of a hill extending from n to s in the central part of which two smaller elevations were located. the western one was slightly higher than the eastern one. in this latter area the 97 graves were found. another three graves – also belonging to this age – were found 80 m to the north from the cemetery. on the ridge of the hill, however, findings of two other archaeological periods were also excavated. according to archaeological interpretation prior to the cemetery a tell was located here in the roman imperial period (2th-4th centuries ad) several buildings and more than 300 pits of which were explored in the north-west part of the excavation. a significant part of these was found beneath the cemetery that is why a few of the graves were unintentionally occupying some of the earlier pits. five bronze age urn graves containing ashes were also excavated together with a few other pits probably from the same period as well. age of the bronze age pits and graves is between 2800 bp and 800 bp. now the area can be regarded as entirely excavated, no findings from earlier ages were found. conclusions archaeologists excavated a cemetery from the time of the hungarian conquest, a tell from the roman imperial age underneath and finally bronze age urn graves from the strata of a sand dune. people of various times utilized the natural conditions of the area. there was a stream in the vicinity of the natural elevation thus the area was optimal for settling even though on wind-blown sand. strata of the sand dune were divided by a fossil soil layer suggesting that the formation of the dune took place over at least two dry periods separated by a wetter period. thickness of the soil indicates that the wetter period lasted for several thousand years. peoples of different ages (bronze age, imperial age) settled in this wetter time period. based on the position of the findings this 60 cm thick soil layer was formed between the imperial age and the bronze age. following the imperial age the area was covered by wind-blown sand in the drier periods. graves were placed generally at a depth of 1-2 m. most of the graves from the hungarian conquest were found in the upper part of the fossil soil layer at around this depth. this indicates that by the time of the hungarian conquest at least 1.5-2 m thick wind-blown sand covered the soil layer and the 1.5-2 m deep graves were emplaced in this wind-blown sand layer. the fact that 3-4 m thick wind-blown sand was removed from the top of the fossil soil layer suggests that sand movements took place following the 10th century as well. between the age of the hungarian conquest and nowadays another 2 m of wind-blown sand accumulated. regarding the development of the area, wind-blown sand was accumulated by wind in the late glacial from the fluvial sand material of the alluvial fan. on the surface of this sand soil developed in the wet periods of the holocene. the dune rising above its vicinity was an excellent location for the bronze age people to settle. since both the bronze age and the imperial age findings were excavated from beneath the graves of the hungarian conquest age from the fossil soil layer no aeolian land formation can be suggested in the area for this period. following the imperial age – like in other sand areas of the great hungarian plain – wind-blown sand was formed repeatedly in the dry periods. meanwhile, in the age of the hungarian conquest the area became inhabited again, however, climatic conditions and anthropogenic effects impeded the development of a soil horizon. thus no soil layer divides the accumulated 3-4 m of windblown sand. acknowledgement the research was supported by the hungarian scientific research fund project no. k 83560. references borsy z. 1961. a nyírség természeti földrajza. budapest: akadémiai kiadó. 227 p borsy z.  csongor é.  félegyházi e.  lóki j.  szabó i. 1981. a futóhomok mozgásának periódusai a radiocarbonvizsgálatok tükrében aranyosapáti határában. szabolcsszatmári szemle 36/2: 45-50 cholnoky j. 1910. az alföld felszíne. földrajzi közlemények 38/10: 413-436 kiss t. 2000. futóhomok területek felszíndinamikája természeti és társadalmi hatások tükrében dél–nyírségi vizsgálatok alapján. phd dissertation. faculty of sciences, university of debrecen. 128 p kiss t. – sipos gy. 2006. emberi tevékenység hatására meginduló homokmozgások a dél-nyírségben egy zárt buckaközi mélyedés szedimentológiai elemzése alapján. szabó j. (ed.) földrajzi tanulmányok lóki józsef 60. születésnapja alkalmából. debrecen: university press. 116-126 28 buró, b. – jakab, a. – lóki, j. joeg vi/1-4 lóki j. 1985. a februári nyírségi szélerózióról. szabolcsszatmári szemle 20: 38-44 lóki j. 2006. holocén felszínváltozás a hazai futóhomok területeken. scientific publications of the iii. hungarian geographical conference. cd-rom. budapest: mta fki. isbn 963-9545-12-0 lóki j. – hertelendi e. – borsy z. 1993. new dating of blown sand movement in the nyírség. acta geographica debrecina 32: 67-76 lóki j. – schweitzer f. 2001. fiatal futóhomokmozgások kormeghatározási kérdései – duna-tisza közi régészeti feltárások tükrében. acta geographica geologica et meteorologica debrecina 35: 175-183 lóki j. – demeter g. – négyesi g. – vass r. – molnár m. 2008. holocén korú homokmozgások a nyírségben. in: tanulmányok a geológia tárgyköréből dr. kozák miklós tiszteletére. debrecen: university press. 111-123 nagy j. 1908. a nyírség domborzati viszonyai. kolozsvár: bonaventura könyvnyomda. 20 p nyári d. – kiss t. – sipos gy. 2006. történeti időkben bekövetkezett futóhomok mozgások datálása lumineszcenciás módszerrel a duna-tisza közén. scientific publications of the iii. hungarian geographical conference. cd-rom. budapest: mta fki. isbn 963–9545–12–0 sümeghy j. 1944. a tiszántúl. magyar tájak földtani leírása 6. budapest: attila-ny. rt. 208 p impact of low-dose municipal sewage sludge compost treatments journal of environmental geography 13 (1–2), 25–30. doi: 10.2478/jengeo-2020-0003 issn 2060-467x impact of low-dose municipal sewage sludge compost treatments on the nutrient and the heavy metal contents in a chernozem topsoil near újkígyós, hungary: a 5-year comparison zsuzsanna ladányi1*, katalin csányi1, andrea farsang1, katalin perei2, attila bodor2, adrienn kézér1, károly barta1, izabella babcsányi1 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6720 szeged, hungary 2department of biotechnology, university of szeged, közép fasor 52, h-6726 szeged, hungary *corresponding author, e-mail: ladanyi@geo.u-szeged.hu research article, received 20 february 2020, accepted 15 april 2020 abstract agriculture is one of the major fields, where sewage sludge can be used. its high nutrient content can contribute to the improvement of important soil properties, such as nutrient content, water balance and soil structure. however, sewage sludge may contain hazardous components, such as pathogens and pollutants. therefore, it is important to monitor the effects of its field application. in this paper, we assessed the impacts of two low-dose (2.5 m3/ha) municipal sewage sludge compost applications (in 2013 and in 2017) in a 5.6 ha arable land in southeast hungary (near újkígyós), located in the hungarian great plain. the nutrient and the heavy metal contents in the upper soil layer (0-30 cm) of the studied chernozem soils were compared between two sampling campaigns in 2013 (before the compost applications) and in 2018 (after the compost applications). basic soil properties (ph, salinity, humus content, carbonate content, arany yarn number) complemented with nutrient content (k2o, p2o5, no2+ no3) and heavy metal content (cd, co, cr, cu, ni, pb and zn) analyses were performed. the results show that no significant change can be noticed in the baseline parameters over the 5-year period. the slight increase in the p2o5, no2+ no3 content is closely related to the beneficial effects of the sewage sludge deposition. the soil-bound heavy metal load did not increase significantly as a result of the compost treatments, only nickel showed a slight increase in the topsoil. in all cases the heavy metal concentrations did not reach the contamination thresholds set by hungarian standards. the results provided positive evidences proving that low dose municipal sewage sludge compost disposal on agricultural land is safe, and can be considered as a sustainable soil amendment for agriculture in compliance with legal requirements. keywords: sewage compost, treatment, heavy metal, nutrient content, agricultural application introduction sewage sludge, as a by-product of the wastewater treatment, is rich in organic and inorganic plant nutrients, therefore it can be used as an alternative to mineral fertilizers in agricultural fields (singh 2008). sewage sludge disposal in agriculture is an increasingly popular way of reusing sewage sludge, as it enables the recycling of valuable components, such as organic matter (csányi et al., 2018), n, p and other nutrients (kádár, 2013; babcsányi et al., 2019). besides amending the soil with plant nutrients and organic matter, sewage sludge application can introduce into the soil some hazardous pollutants, such as heavy metals (moreno et al., 1997). according to the 9th technical assessment on the implementation of the urban waste water treatment directive of the european union (ta uwwtd, 2017), the overall reported production of sludge in eu28 in 2014 was just over 8.7 mio t/year, from which 44% was reused for “soil and agriculture”. according to the national sewage sludge management strategy of hungary (20142023) 38% of the total amount of municipal sludge was used in agriculture as sludge, compost or compost product in hungary in 2013 (while 46%, 5%, 2%, 9% were used for land reclamation, energy purposes, landfilling and other purposes, respectively). land application of sewage sludge is regulated only by the concentration of heavy metals as specified in the council directive 86/278/eec (cec, 1986). hungary, as most of the eu countries, adopted even more stringent limits for sludge use in agriculture by setting lower limits for heavy metals in comparison with the european directive 86/278/eec, furthermore, introduced limit values for other elements as well (hudcová et al., 2019) for the disposal of sewage sludge, it is essential to assess the composition and its impact on the soil as it can change the macroand micro-nutrient content, organic matter content, adsorption capacity, soil structure and water management (kádár, 2013). in addition, sewage sludge can be a potential source of hazard due to its heavy metal content and microbial composition (moreno et al. 1997) (vermes, 1997; kocsis, 2011). increased heavy metal content can cause a change in the soil biota (uri et al., 2005), and can ultimately endanger human health by entering the food chain. although nutrients (eg. n, p) are essential for plant growth, when applied excessively, however, they may accumulate in the topsoil, can be leached and transported off-site by drainage systems or can be transported by erosion posing risk to (sub)surface 26 ladányi et al. 2020 / journal of environmental geography 13 (1–2), 25–30. waters (hudcová et al., 2019). therefore, it is important to monitor the long-term effects of the landapplication of sewage sludge. this study investigates the impacts of two applications of municipal sewage sludge compost (in 2013 and in 2017) on chernozem soils based on comparing soil parameters between 2013 and 2018. for this purpose, potential changes in the basic soil physical and chemical features were assessed (ph, salt content, humus content, carbonate content, arany yarn number, nutrient and heavy metal content). the specific objective is to evaluate if the low dose application of municipal sewage sludge compost causes a significant increase in the soil-bound heavy metal concentrations and how the nutrient content is affected. study area and methods the study area is located near újkígyós, a settlement in the trans-tisza region of the hungarian great plain (fig. 1). the studied plot is an 5.6 ha arable land with highly fertile chernozem soils, where municipal sewage sludge compost was spread twice in 2013 and in 2017 (2.5 m3/ha). the parameters of the deposited sludge compost are presented in table 1. prior to the first sludge compost application in 2013, a soil protection plan was compiled for the study area based on a detailed soil survey (according to the hun. decree 40/2008. (ii. 26.), the results of which provide the basis for the comparison with data from 2018. in 2013, composite samples were collected from the upper soil (0–30 cm) from 5 sampling areas of 2500 m2 each within the study area. the arable land was re-surveyed in march 2018, when 6 composite samples were taken from the upper soil (0-30 cm). during the designation of the sampling areas in 2018, a special attention was paid to include areas affected by sewage sludge compost disposal (1,2, 3,4 plots in fig.1.) and also unaffected ones (6,7plots in fig.1.) (kézér, 2018; pálffy et al., 2018). prior to measurements, samples were dried in the laboratory at 40°c in an oven and powdered (< 2 mm) after removing larger organic debris and foreign material. the ph (h2o) was determined using a wtw inolab 720p phmeter, the total water soluble salt content was determined by measuring the conductivity (ok-104 conductivity meter) of the saturated soil paste, the carbonate content (caco3) was determined using the scheibler type calcimeter according to the hungarian standard procedure (msz-08-0206-2: 1978). to measure texture of the samples, arany yarn test was carried out based on the msz08-0205-1978 hun. standard. humus content was measured by colorimetry using helios γ type spectrophotometer based on the msz 21470-52:1983 standard. the macronutrients p2o5 and k2o were extracted using ammonium-lactate, while the nitrogen forms (no2 + no3 -n) were extracted with kcl-solution according to standard procedures (msz20135:1999), measured by fia spectrometer. prior to total metal analyses, soil samples were oven-dired again at 105°c for 24 hours. powdered soil samples (0.5 g) were digested in aqua regia (hydrochloric acid : nitric acid = 3 : 1) in closed vessels in a microwave oven (anton ar multiwave 3000) the metal concentrations in the digested samples were measured by an inductively coupled plasma atomic/optical emission spectrometer (perkin elmer icp-oes optima 7000 dv) (according to the standard: msz 21470-50:2006). fig. 1 location of the study area (újkígyós, hungary) ladányi et al. 2020 / journal of environmental geography 13 (1–2), 25–30. 27 results and discussion the topsoil in the study area is characterized by slightly alkaline ph (7.0-8.1), low salt content (0.02%), moderate humus content (1.53 – 2.52%), low carbonate content (0.14-3.56 %) and a sandy loam texture (fig. 2). there was no statistically significant change in these basic soil parameters between 2013 and 2018 (p≤0.05). as a result of the compost treatment, we would expect the humus content to increase, however a slight decrease can be noticed in the soil humus content in 2018. this observation may be explained by the intensive agricultural production. another possible explanation may be the low-dose and short-term application of the compost at our study site. a previous field study found that a longer term (50 year-long) annually repeated treatment of arable land with organic amendments may be needed for a significant increase in the soil organic carbon pool (sleutel et al., 2006). there is a marked increase in the bioavailable nand pcontents between 2013 and 2018, whereas no significant change can be observed in the k content (fig. 3). these observations confirm that the sludge compost treatments supply with valuable plant nutrients agricultural soils and can be a convenient alternative for mineral fertilizers. moreover, the compost treatment has a longer-term effect compared to mineral fertilizers, because the applied composts supply plants with macronutrients via a slow decomposition process of the organic compost components including the conversion of macronutrients (n, p, s, etc.) into inorganic (and mostly plant available) forms by microorganisms (diacono and montemurro, 2011). heavy metal load did not increase significantly as a result of the sewage sludge compost applications between 2013 and 2018 (fig. 4). among the investigated heavy metals, only nickel showed a slight increase in the topsoil. the heavy metal concentrations are far beyond the contamination thresholds according to the hungarian standards for soil quality (6/2009. [iv. 14.] kvvm-eüm-fvm). our results are in line with the outcome of a similar study conducted over a 6-year period that demonstrated that urban sewage sludge compost (mixed with poplar bark) treatments with similar heavy metal contents presented no danger in the short/medium term either to the environment or to crops even when applied in higher doses (80 -160 t/ha) compared to the doses in the present field survey (pinamonti et al., 1997). an incubation experiment also found that the increase in the total metal content following a single sludge addition (48 t/ha) was negligible in an agricultural calcareous silt loam soil using a mixture of sewage sludge (primary aerobic sludge) and cotton waste (sánchez-monedero et al., 2004). similarly, fang and coworkers (2016) observed no significant increase in the total metal content of a farmland alluvial soil displaying slightly alkaline ph due to a single application of sewage sludge compost at a rate of 48 t/ha. nevertheless, they found that application intensified the leaching of heavy metals due to the increase in the dissolved organic matter of the soil solution. depending on the metal content of the applied sewage sludge compost a significant increase in the total metal content of amended soils may be observed, which raises concerns about the long-term applicability of sewage sludge composts (khadhar et al., 2020). table 1 the quality of the applied municipal sewage sludge compost in 2013 and in 2017. the displayed hungarian threshold for sewage sludge compost applied in agricultural land is specified in the government decree 40/2008. (ii. 26.) parameters compost quality in 2013 compost quality in 2017 hungarian threshold ph (d.w.) 7.64 8.48 dry matter (mg/kg) 181000 24600 organic matter (m/m%) 13.2 5.7 total nitrogen (mg/kg dry w.) 59100 128700 total phosphorus (p2o5 mg/kg dry w.) 19500 16500 total potassium (k2o mg/kg dry w.) 2560 5860 tph (mg/kg) <25 2588 1000 as (mg/kg) 67.6 15.5 25 cd (mg/kg) 0.53 <1 5 co (mg/kg) <1 2.31 50 total cr (mg/kg) 14.2 17.6 350 cu (mg/kg) 81.1 103 750 hg (mg/kg) 0.64 0.46 5 mo (mg/kg) 6.74 6.35 10 ni (mg/kg) 12.4 15.1 100 pb (mg/kg) 18.7 16.3 400 se (mg/kg) <1 <1 50 zn (mg/kg) 444 542 2000 28 ladányi et al. 2020 / journal of environmental geography 13 (1–2), 25–30. fig. 2 basic soil parameters between 2013 and 2018 (before the compost treatments and afterwards) in the topsoils of the study area near újkígyós (hungary) fig. 3 changes in the nitrogen, phosphorus and potassium contents between 2013 and 2018 of the topsoil as a result of the two compost treatments fig. 4 evolution of the soil-bound heavy metal contents (ni, co, cr, cd, zn, pb, cu and as) between 2013 and 2018 at the study site (the red linestands for the contamination thresholds according to the hungarian standards for soil quality (6/2009. [iv. 14.] kvvmeüm-fvm) ladányi et al. 2020 / journal of environmental geography 13 (1–2), 25–30. 29 the beneficial effects of the compost treatment can also be clearly identified if we compare the n-, pand k nutrient content of the control and the treated sampling areas in 2018 (fig. 5). if we separate affected sites according to the timing of the disposal, it can be identified that 1,2 sampling sites (under d isposal in 2018) show higher phosphorus content compared to 3,4, where there was no disposal in 2018 (only before). there is no significant difference between 1,2 and 3,4 in case of the nitrate and potassium. among the heavy metals, copper and zinc show slightly higher concentrations in the soil samples affected by the compost treatment compared to the control soil, which can be explained by their higher concentration in the applied sewage sludge compost as compared to their level in the untreated soils. conclusions the present study investigated the effects of sewage sludge compost applications on chernozem soils in hungary. our study confirmed that there were no significant changes in either the basic soil parameters or the heavy metal load in the topsoil (0-30 cm) over the studied 5-year-period. in contrast, sludge compost treatment added to the soil an excess of slowly decomposing organic matter, rich in macronutrients (eg. nitrogen, phosphorus). thus, properly designed sludge spreading on agricultural land in compliance with legal requirements can improve the nutrient and organic matter content of soils in a sustainable way. the accumulation of heavy metals with potential environmental and human health risks could not be identified. according to our results in 2018, the samples affected by sewage sludge compost applications showed an increased nitrogen and phosphorus content compared to the control areas, while the heavy metals zinc and copper showed somewhat higher values in the samples affected by the compost treatments. our results are in line with previous studies who also did not identify a significant increase in heavy metal concentrations as a result of low doses of sewage sludge disposals (pinamonti et al., 1997; sánchez-monedero et al., 2004). the resulting data also provide evidence that in case the applied sewage sludge composts meet the quality guidelines and requirements for the treatment doses set in the government decree 40/2008. (ii. 26.), their field application as fertilisers can be considered as a sustainable management practice of secondary raw materials. the study confirmed the safe applicability of low dose municipal sewage sludge composts in a hungarian study area. further study sites are under investigation to investigate the impact of regular lowdose municipal sewage disposal within the broader study area. acknowledgements the support of european union and hungarian state (grant agreement no. efop-3.6.2-162017-00010) is gratefully appreciated. references babcsányi, i., ladányi, zs., perei, k., bodor, a., barta, k., kézér, a., csányi, k., pálffy, b., farsang, a. 2009. the impact of sewage sludge disposal on the bacterial activity, nutrient and heavy metal content of chernozem soils and on the plant productivity, se hungary. in: rákhely, g., hodúr, c., lemmer, b., jákói z. (ed) ii. sustainable raw materials international project week and scientific conference: book of abstracts szeged, hungary: university of szeged, 33–33. banerjee, m.r., burton, d.l., depoe, s. 1997. impact of sewage sludge application on soil biological characteristics. agriculture, ecosystems & environment 66, 241–249. doi: 10.1016/s01678809(97)00129-1 csányi, k., pálffy, b., ladányi, zs., barta, k., farsang, a. 2018. tartós szennyvíziszap kihelyezés hatása a talaj szénforgalmára. in: fazekas, i., kiss, e., lázár, i. (ed.) földrajzi tanulmányok 2018 debrecen, magyarország: mta dab földtudományi szakbizottság, 187–189. diacono, m., montemurro, f. 2011. long-term effects of organic amendments on soil fertility. in: lichtfouse, e., hamelin, m., navarrete, m., debaeke, p. (eds.) sustainable agriculture volume 2. springer netherlands: dordrecht. fig. 5 n-, pand k-nutrient and heavy metal contents are compared between the compost treated and the control sites in soil samples from the survey in 2018 https://www.sciencedirect.com/science/journal/01678809 https://www.sciencedirect.com/science/journal/01678809 30 ladányi et al. 2020 / journal of environmental geography 13 (1–2), 25–30. fang, w., wei,y., liu, j. 2016. comparative characterization of sewage sludge compost and soil: heavy metal leaching characteristics. journal of hazardous materials 310, 1–10. doi: 10.1016/j.jhazmat.2016.02.025 hudcová, h, vymazal, j., rozkošný, m. 2019. present restrictions of sewage sludge application in agriculture within the european union. soil and water research 14/2, 104–120. doi: 10.17221/36/2018-swr kádár, i. 2013. szennyvizek, iszapok, komposztok, szervestrágyák a talajtermékenység szolgálatában. mta taki, budapest, 347 p. kézér, a. 2018. szennyvízisap-kihelyezés hatása a talaj nehézfémtartalmára és baktérium összetételére. diplomamunka. szegedi tudományegyetem, természeti földrajzi és geoinformatikai tanszék, 64 p. khadhar, s., sdiri, a., chekirben, a. azouzi, r., charef, a 2020. integration of sequential extraction, chemical analysis and statistical tools for the availability risk assessment of heavy metals in sludge amended soils. environmental pollution 263, 114543. doi: 10.1016/j.envpol.2020.114543 kocsis, i. (2011). hígtrágya és szennyvíziszap kezelés. szent istván egyetem, 93 p. moreno, j., carlos garcía, l., hernández, t., ayuso, m. 1997. application of composted sewage sludges contaminated with heavy metals to an agricultural soil. soil science and plant nutrition 43, 565–573. doi: 10.1080/00380768.1997.10414783 national sewage sludge management strategy of hungary 2014-2023. szennyvíziszap kezelési és hasznosítási stratégia (2014-2023). available at: http://biopsol.hu/files/file/szennyviziszap_kezelesi_es_hasznosit asi_strategia_2018_2023.pdf pálffy,b., farsang, a., kézér, a., barta, k., csányi, k., ladányi, zs. 2018. tartós szennyvíziszap kihelyezés hatása a talaj tápanyag-, toxikuselem-összetételére, valamint a baktériumaktivitásra. talajtani vándorgyűlés program és absztrakt füzet, 2018. 08. 29 – 09.01. pécs, 96–97. pinamonti, f., stringari, g., gasperi, f., zorzi, g. 1997. the use of compost: its effects on heavy metal levels in soil and plants. resources, conservation and recycling 21, 129–143. doi: 10.1016/s0921-3449(97)00032-3 sánchez-monedero, m. a., mondini, c., de nobili, m., leita, l., roig, a. 2004. land application of biosolids. soil response to different stabilization degree of the treated organic matter. waste management 24, 325–332. singh r.p., agrawal, m. 2008. potential benefits and risks of land application of sewage sludge. waste manag. 28, 347–358. doi: 10.1016/j.wasman.2006.12.010 sleutel, s., de neve, s., németh, t., tóth, t., hofman, g. 2006. effect of manure and fertilizer application on the distribution of organic carbon in different soil fractions in long-term field experiments. european journal of agronomy 25, 280–288. doi: 10.1016/j.eja.2006.06.005 ta uwwtd 2017. 9 th technical assessment on uwwtd implementation https://ec.europa.eu/environment/water/waterurbanwaste/implementation/pdf/9th%20technical%20assessme nt%20of%20information%20on%20the%20implementation%20 of%20council%20directive%2091-271-eec.pdf uri, zs., lukácsné veres, e., kátai, j., simon, l. 2005. különböző módon előkezelt szennyvíziszapok hatása a talaj mikroorganizmusaira és enzimaktivitására. agrokémia és talajtan 54/3-4, 439–450. vermes, l. 1997. vízgazdálkodás. mezőgazdasági szaktudás kiadó, budapest, 462 p. 40/2008. (ii. 26.) korm. rendelet a szennyvizek és szennyvíziszapok mezőgazdasági felhasználásának és kezelésének szabályairól . introduction study area and methods results and discussion conclusions acknowledgements references statistical analysis of weather parameters for sustainable flight operation in nigeria journal of environmental geography 14 (3–4), 47–53. doi: 10.2478/jengeo-2021-0011 issn 2060-467x statistical analysis of weather parameters for sustainable flight operation in nigeria abiodun daniel olabode1 1department of geography and planning sciences, adekunle ajasin university, akungba-akoko, ondo state, nigeria *corresponding author, email: olabiodun4real@gmail.com research article, received 28 june 2021, accepted 20 october 2021 abstract the recent complications in the weather system, which oftentimes lead to flight cancellation, delay and diversion have become a critical issue in nigeria. this study however considers the weather related parameters and their impacts on flight disruption in the country. weather data (on thunderstorm, wind speed and direction, visibility and cloud cover) and flight data (delay, cancellation and diversion) were collected from murtala international airport, ikeja-lagos, nigeria. the data covered the period between 2005 and 2020. however, regional climate models (rcms) were also used to run climate data projections between year 2020 and 2035 in the study region. the study employed statistical package for social sciences (spss) software for the descriptive and inferential analysis. time series analysis, pearson moment correlation for interrelationship among the weather parameters and the flight disruption data, and multiple linear regression analysis were applied to determine the influence of weather parameters on flight disruption data. results show that cloud cover and high visibility are negatively correlated. wind speed has positive relationship with wind direction; and an inverse relationship between visibility, thunderstorm, and fog. direct relationship exists between highest visibility and thick dust, wind speed and cloud cover. thick dust, wind speed and cloud cover indicate increased visibility level in the study area. flight delay is prominent over flight diversion and cancellation, which indicates their relevance in air traffic of the study area. the prediction model indicates high degree of cloud cover at the beginning of every year and later declines sharply in 2035, the visibility flattens out by the year 2025, and low pattern of thick dust was calculated in the same pattern in 2011, 2016 and 2027. based on this conclusion, the study recommends accurate weather reporting and strict compliance to safety regulations, and attention should be paid to changing pattern of weather parameters in order to minimize fight related disasters. keywords: weather parameters, air traffic, flight delay, flight diversion, flight cancellation introduction weather is extremely changeable because the atmosphere that constitute it is never static. consequently, it is crucial to understand the mechanism of this variation to mitigate the negative effects on the society. the general public and the aviation industry in particular have become aware of this variability, and feel its negative impacts where they live. there has been an increasing awareness, concern and studies on weather parameters as one of the causes of air disasters over the years. the importance of such studies cannot be overemphasized if air safety must be achieved. however, there is still low level of recognition and research attention on some weather parameters in nigeria. aviation is one of the critical parts of any national economy. it provides fastest means of moving people and goods among the world’s nations for enabling economic growth (waitz et al., 2004). the volume of air transportation is increasing rapidly; though the safety of aviation becomes an important problem over many countries. as noted by mcfadden and hosmane (2001), accident of an aircraft usually leads to human injury and loss of life. as noted by nwaogbe et al. (2013), air transportation is a major industry in its own right and it also provides important inputs into wider economic, political, and social processes. the demand for its services, as with most transport, is a derived one that is driven by the needs and desires to attain some other final objective. lack of air transport, as with any other input into the economic system, can prevent efficient growth. the nigerian aviation industry witnessed its darkest period between 2003 and 2010, when several aircraft accidents occurred, resulting in loss of lives. it was however observed that air crashes occurred between 2003 and 2006 mostly as a result of weather and wind shear anomalies. knecht (2008) confirmed that most of the plane crashes could be associated with poor conditions of weather and some other factors. similarly, flight delay, cancellation, diversion and air craft accidents affect the nigerian aviation industry as ayoade (2004) has earlier noted that “the vagaries of weather with references of the various meteorological parameters act malevolently against most of man’s socio-economic activities”. consequently, flight delay, flight cancellation, and flight diversion were adopted as control measure of avoiding aircraft accidents. weather, which is defined as the snapshot of atmospheric conditions and a technical status report of the earth atmosphere heat energy budget or simply defined as an everyday experience (stringer, 1989), can evolve at a mailto:olabiodun4real@gmail.com 48 olabode 2021 / journal of environmental geography 14 (3–4), 47–53. rapid rate over a wide spatial extent when compared with other factors that may affect the safe conduct of flight. thus, the spectrum of weather information is an important component for flight safety and the efficient management of air transport in future (mirza et al., 2009). in some cases, weather is completely neglected. for instance, arizona-ogwu (2008), in a study on safety of air transport in nigeria reported that experts attributed the causes of air disaster to pilot error (human related), pilot error (weather related), pilot error (mechanical related), other human error, weather, mechanical failure, sabotage etc. nevertheless, he attributed it to out-dated air crafts being flown everywhere in nigeria rather than what the experts revealed. he also reported that between 1988 and 2005 (in 17 years), the private airlines recorded 12 crashes, of which only one had no casualties, while the total deaths recorded was 762. there are three major weather phenomena, which pose severe threat to air transportation under the two distinct seasons observed in nigeria. thunderstorms occur within the wet/rainy season, while fog and dust haze (harmattan) are typical in the dry period of the year. this implies that the phenomenon of plane crash is tied to these two major seasons in nigeria. thus, assessment of relevant weather parameters that include temperature, humidity, wind, cloud cover, visibility, fogs, thunderstorms, and dust haze is critical for aviation activities. this is more so considering aviation as one of the earliest industries involved in using weather as the basis for its operational decision making. good knowledge of flight operation vis-à-vis operational weather situation is a precondition for passengers’ safety and protection of goods. riehl (1965) has shown that low ceilings and visibilities cause the major traffic disruptions at airport terminals, and the problem is said to remain unchanged over the years. in addition, smith (1975) reports that despite increasing sophistication of automatic landing equipment, poor visibility from layer of fog, mist or thick haze and low cloud ceilings is probably the major impediment to airport operations throughout the world. the major challenges facing the aviation industry has been to adapt to the vigorous of an extreme and variable weather environment. in prospect of this fact, it becomes highly desirable to ascertain the nature of weather parameters in an area. this is because the safety of modern air communication is closely tied to accurate weather reports from the meteorological stations, and weather conditions influence the performance and durability of aircraft engines. more so, wind affects the degree of smoothness of the air and brings about changes in weather, which makes a difference between safe flight and disaster. the apprehension is that, the incessant flight cancellation, re-routing, delay, diversion of recent, mostly because of this natural factors (bad and inclement weather) may remain or even increase with the present concept of climate change and its resultant global warming if something is not done to mitigate the situation. the focus of this study is on the statistical analysis of weather parameters for flight operation in lagos, ikeja, nigeria; aiming to describe various parameters influencing flight operation, and relationship among weather parameters for supporting sustainable flight planning. evaluating the effects of cloud cover, thunderstorm, visibility, wind speed and direction on flight operation and how weather conditions could be managed for sustainable flight operation in murtala mohammed international airport is the prime focus of this study. study area the murtala mohammed international airport owned and operated by the federal airport authority of nigerian (faan) is situated in the suburb of ikeja, 22 km northwest of lagos. the coordinate of the airport is 06°34’39’’n and 03°19’16’’e (fig. 1). fig. 1 map of lagos state showing study area at the murtala mohammed international airport (source: ministry of lands and housing, ikeja, 2020) olabode 2021 / journal of environmental geography 14 (3–4), 47–53. 49 lagos experiences tropical wet and dry savannah climate aw according to the köppen climate classification. the heavy rainy season is between april and june, and the milder rainy season occurs between october and november. a very brief dry season is in august and september, whereas a long dry period occurs from december to march. the average rainfall between may and july is over 300 mm, while it is only 75 mm to 100 mm in august and september. in january, the average rainfall is only 35 mm (fig. 2). the long dry season is followed by dry wind coming from the sahara desert, which is the most intense during the months from december to february (pospichal, et al., 2010). temperature in lagos does not vary greatly. march is generally the hottest month, with an average temperature reaching 29°c (fig. 3). july is usually the coolest month, averaging 25°c. the average temperature in january is 27°c. temperature in lagos rarely gets colder than 20°c and rarely gets hotter than 30°c. the month with the highest average low temperature is march (23.8°c). the coldest month (with the lowest average low temperature) is august (21.7°c). fig. 2 average monthly rainfall (mm) in lagos (source: weather-and-climate.com) fig. 3 lagos average monthly temperature in lagos (source: weather-and-climate.com) fig. 4 average wind speed (m/s) in lagos (source: weather-and-climate.com) furthermore, lagos state is under the influence of the south west trade wind at most times of the year, and this account for its moderate temperature throughout the year. the highest average wind speed recorded was between july and august, which is above 6 m/s (fig. 4). methods in this study monthly mean temperature, wind, visibility, cloud cover, thunderstorm, fog, and dust data were used for the period of 2005–2020. these parameters were selected because they were available from ground measurements. the possibilities of these parameters are noticed in reduction of visibility, creation of turbulence, and general poor aircraft performance. the focus was on analysing wind speed and direction (knot), cloud cover (okta), thunderstorm, fog (mm), dust, visibility (mi) as they affect flight delay, cancellation, and diversion in the study area. the monthly data were obtained from the nigerian meteorological agency (nimet), and monthly flight disruption data on flight diversion, delay and cancellation were collected from nigerian civil aviation authority (ncaa), oshodi, lagos state, nigeria. regional climate models (rcms) were used to run climate data projections between year 2020 and 2035 within the study region. the study employed statistical package for social sciences (spss) software for the descriptive and inferential statistics that include, time series for trend analysis, pearson moment correlation for interrelationship among the weather parameters and the flight disruption data, and multiple linear regression analysis to determine the influence of weather parameters on flight disruption data. the correlation was tested at 5% level of significance with pearson product moment correlation. the rational for the choice of the statistics is due to the fact that all the weather variables are metric. the ofd is a simple device suitable for the detection of fog and cloud. calculations show that the ofd responds to visibility reductions by droplets in the size range of 2– 20 mm. fog is large density of small water droplets that are small enough to "float" in the air. the size of fog particles is typically 5–50 µm (0.005–0.05 mm). the dust measuring device pce-mpc 20 was used to measure the particles in the atmosphere. the measurable particle sizes in the particle collector are 0.3, 2.5 and 10 μm. results and discussions relationship among weather parameters in the study area table 1 shows the correlation between all studied weather elements in the study area. the results of the analysis indicate that all the tested weather parameters have correlation coefficients that are far from the value of 1.0. however, there is an inverse relationship between highest visibility and visibility, thunderstorm, fog, and wind direction; while direct relationship exists between highest visibility and thick dust, wind speed and cloud cover. also, the correlation matrix (table 1) indicates negative relationship between the highest visibility and thunderstorms, thick dust, fog, cloud cover and wind 50 olabode 2021 / journal of environmental geography 14 (3–4), 47–53. direction with -0,077, -0.58, -0.076, -0.117, -0.029 and 0.072 respectively. this simply explained by the influence of these parameter on visibility. it is worthy to note that dust, wind speed and cloud cover could indicate increased visibility level as an environmental factor in the study area. however, wind speed has positive relationship with recorded highest visibility of the study area. thunderstorm has negative relationship with highest visibility, visibility, dust, winds, fog and cloud cover. further, it was established that cloud cover and highest visibility are positively correlated. this shows that the highest visibility experience in the study area depends on the level at which cloud cover is perceived. wind direction (0.470) has positive relationship with wind speed. there is negative relationship between thick dust and fog (r=0.00, p>0.05). however, all other weather elements show positive association with thick dust. the association is, also, not significant. there is no relationship between fog (r=0.00, p>0.05) and thick dust, whereas, wind speed (r=0.03, p>0.05), cloud cover (r=0.07, p>0.05), and wind direction (r=0.12, p>0.05) show direct correlation with thick dust but the relationships are not significant. the relationship between fog and wind speed (r=0.05, p>0.05) is negative; while cloud cover (r=0.03, p>0.05) and wind speed (r=0.14, p>0.05) show positive relationship with fog, although, the correlation is not significant in any of the cases. both cloud cover (r=0.06, p>0.05) and wind direction (r=0.5, p<0.05) show positive relationship with wind speed but not significant. there is a significant moderate relationship between wind speed and wind direction. it is evident, that strong vertical wind shear is important to severe thunderstorm development. wind shear influences a storm in potentially several ways of significant increase of wind speed with height will tilt a storm's updraft, strong upper tropospheric winds evacuates mass from the top of the updraft, directional shear in the lower troposphere helps initiate the development of a rotating updraft, and the shear environment important in determining the thunderstorm type. this relationship could mean that wind speed is propelled by the direction of increased wind pressure. the relationship between cloud cover and wind speed (r=0.01, p>0.05) is positive but weak and not significant. impact of weather parameters on flight disruption in the study area the effect of weather elements on flight operations in the study area was presented in table 2 with multiple linear regression output. three approaches were designed to test the impacts of weather elements on flight disruption data. flight disruptions were measured by numerically capturing number of flight delay, number of flight diversion, and number of flight cancellation over time. table 2 presents statistics of recorded flight disruption parameters in the study area. it was revealed that flight delay has the mean of 44.06, flight diversion has 22.13, and flight cancellation has 19.19. considering these calculated means, it is obvious that flight delay is prominent among other parameters of flight disruption in the study area. however, the results of mean on flight diversion and cancellation are not too far apart, which indicates their relevance in air traffic. to this, rodenhuis (2004) submitted that critical weather phenomenon reduces the operational capacity of regions entire airspace through delays, diversion and flight cancellations. in table 3, the multiple linear regression model presents highest visibility, thunderstorm and dust, cloud table 1 correlation matrix of weather parameters in the study area. weather parameters highest visibility visibility thunderstorm thick dust fog wind speed cloud cover wind direction highest visibility 1.000 visibility 0.077 1.000 thunderstorm -0.058 -0.108 1.000 thick dust -0.076 -0.000 -0.031 1.000 fog -0.117 0.016 -0.142 -0.004 1.000 wind speed 0.133 0.003 -0.157 0.028 -0.052 1.000 cloud cover -0.029 -0.144 -0.109 0.073 0.027 0.058 1.000 wind direction -0.072 0.085 -0.125 0.122 0.135 0.470 0.095 1.000 table 2 recorded annual flight disruptions between 2005 and 2020 variables n minimum maximum mean std. deviation diversion 16 11.00 40.00 22.1250 8.77021 delay 16 16.00 70.00 44.0625 17.22196 cancellation 16 3.00 30.00 19.1875 6.77465 olabode 2021 / journal of environmental geography 14 (3–4), 47–53. 51 cover and wind direction with positive beta values of 0.511, 0.434, 0.051, 0.053, and 0.183 respectively. this result indicates that climate data (coeff=4.62, p<0.05) and thunderstorm (coeff=3.33, p<0.05) are significant predictor of flight delay relating to diversion indicates cloud cover with (coeff=3.53, p<0.05). the beta coefficient has positive values on high visibility, thunderstorm, tick dust, cloud cover and wind. this indicates that for every 1-unit increase in the weather parameters that were positive, the delay in flight will increase by the beta coefficient values. however, the negative values explained 1-unit reduction by the beta coefficient values. further, it was indicated in table 3 that cloud cover has significant impact on flight diversion. it was also revealed that thunderstorm (coeff=1.71, p<0.05) and wind speed (coeff=2.20, p<0.05) have significant influence on flight cancellation. the thunderstorm has highest beta coefficient being the prominent predictor of flight cancellation. it was observed that the faster the wind speed coupled with high degree of thunderstorm, more flight cancellations are usually recorded. the study of weli and ifediba (2014) confirmed that various weather hazards which include thunderstorm, fog, dust haze and line squall affect flight operation such as flight delays, diversion and cancellation. also, the current study supports the findings of schaefer and millner (2001) who opined that weather is the single largest contributor to delays in the efficiency of flight operation. it is becoming the dominant cause of delay in nigeria. flights can incur delays while airborne or on the ground, for example, a late arrival of one flight may cause a late departure of the next flight on the itinerary of the aircraft. projection of weather parameters from 2005 to 2035 this study revealed how the studied weather parameters have contributed, and will contribute to disruption of aircraft operation between years 2005 and 2019 with projection from 2020 to 2035. the annual mean wind speed and direction, annual average of flight disruptions, horizontal visibility, annual total cloud cover, and annual average of fog, haze and thunderstorm were major parameters under consideration. the highest visibility occurred as seasonal phenomenon from the year 2006 to the peak of year 2020 (fig. 5). however, the highest visibility declines sharply with a rise in 2025. it was further observed that the visibility will flatten out beyond year 2025. table 3 regression analysis of the effect of weather parameters on flight disruption in the study area coefficient p-value beta coefficient delay highest visibility 4.619 0.000 0.511 visibility -0.009 0.207 -0.159 thunderstorm 3.328 0.001 0.434 thick dust 0.876 0.616 0.051 fog -2.755 0.345 -0.118 wind speed -1.535 0.323 -0.140 cloud cover 2.377 0.636 0.053 wind direction 0.125 0.108 0.183 constant -243.132 0.577 diversion highest visibility -0.067 0.936 -0.016 visibility -0.005 0.373 -0.178 thunderstorm 0.339 0.640 0.093 thick dust 0.957 0.471 0.125 fog -1.711 0.439 -0.154 wind speed -0.242 0.837 -0.046 cloud cover 3.529 0.619 0.089 wind direction 0.059 0.313 0.181 constant -152.595 0.645 cancellation highest visibility 0.567 0.156 0.155 visibility -0.001 0.760 -0.033 thunderstorm 1.709 0.000 0.550 thick dust -0.965 0.125 -0.148 fog -0.854 0.409 -0.090 wind speed 2.201 0.000 0.491 cloud cover -3.466 0.875 -0.015 wind direction 0.033 0.223 0.120 constant 6.774 0.965 52 olabode 2021 / journal of environmental geography 14 (3–4), 47–53. thunderstorm shows a seasonal trend throughout 2005 to 2006 after which it reached its peak in 2020 with sharp upward increase in 2026, 2030 and 2034 (fig. 6). the thick dust had a very low abundance in 2005 and ceased to exist shortly after until 2008 when it peaked to its first highest point. it declined to zero level in 2011 till 2015 and peaks upward in 2019 (fig. 7). this low pattern of thick dust was observed in the same configuration in 2011, 2016 and 2027. figure 8 shows that the trend of fog increases in 2015 and 2030 with possible sharp decline in 2035. trend shows a regular short period of peak for fog. almost every year is devoid of long period of fog. fog continued to exist in short period from 2005 to 2013, however, it ceased to exist from 2015 to 2020. the observed trend further indicates visible pattern of fog between 2023 and 2028, which may not have regular trend until 2035. in figure 9, the trend of wind speed shows somewhat smooth directional pattern starting at a high level in 2005 and keeps declining gradually in each successive year till 2011. later in 2013, the trend peaked to reach its highest point with downward trend till 2035. the trend in figure 10 shows high degree of cloud cover at the beginning of every year and later declines sharply. however, the trend further shows declining pattern in 2035. figure 10 further indicates consistent declining pattern of cloud cover in 2035. however, the lowest downward trend would be observed in 2031. cloud cover shows a seasonal pattern throughout the reviewed period and it is forecast that the trend will continue till 2034. fig. 5 projected trend of the highest visibility from 2005 to 2035 fig. 6 projected trend of thunderstorms from 2005 to 2035 fig. 7 projected trend of thick dust from 2005 to 2035 fig. 8 projected trend of fog from 2005 to 2035. fig. 9 projected trend of wind speed from 2005 to 2035 fig. 10 projected trend of cloud cover from 2005 to 2035 olabode 2021 / journal of environmental geography 14 (3–4), 47–53. 53 conclusion this study has analysed weather parameters along with identified cases of flight disruptions in nigeria. it was established that cloud cover and highest visibility are negatively correlated. this shows that the highest visibility experienced in the study area depends on the level at which cloud cover is perceived. wind direction has positive relationship with wind direction. it was established that there is an inverse relationship between visibility, thunderstorm, fog, and wind direction; while direct relationship exists between highest visibility and thick dust, wind speed and cloud cover. it is worth to note that dust, wind speed and cloud cover could indicate increased visibility level as an environmental factor in the study area. considering the calculated means for flight disruption parameters, it is obvious that flight delay is prominent over flight diversion and cancellation. however, the results of the mean on flight diversion and cancellation are not too far apart, which indicates their relevance in air traffic. the prediction model indicates; high degree of cloud cover at the beginning of every year and later declines sharply in 2035, regular short period of peak for fog, that the visibility will flatten out by the year 2025, and that low pattern of thick dust was observed in the same pattern in 2011, 2016 and 2027. based on this conclusion, the study recommends accurate weather reporting and strict compliance to safety regulations, and attention should be paid to changing pattern of weather parameters in order to minimize fight related disaster. references arizona-ogwu, l.c. 2008. airports for lease: is faan a fun? nigeriaworld, march 4th. ayoade, j.f. 2004. introduction to climatology for the tropics. spectrum books ltd., ibadan, xvii. 297 p. knecht, w.r. 2008. use of weather information by general aviation pilots, part ii, qualitative: exploring factors involved in weather-related decision making. (technical report dot/faa/am08/7). washington, dc: federal aviation administration, office of aerospace medicine. 1–7. mcfadden, k. l., hosmane b. s. 2001. operations safety: an assessment of a commercial aviation safety program. journal of operations management 19, 579–591. doi: 10.1016/s02726963(01)00062-6 mirza, a.k., page, c., geinde, s. 2009. an approach to flight safeusing gml/xml objects to define hazardous volume space for aviation, france. retrieved september 25, 2020 from flysafepaper.htm.1–14. nwaogbe, o. r., wokili, h., omoke, v., asiegbu, b. 2013. an analysis of the impact of air transport sector to economic development in nigeria. iosr journal of business and management 14(5), pp. 41–48. doi: 10.9790/487x-1454148 pospichal, b., karam, d.b., crewell, s., flamant, c., hünerbein, a., bock, o., saïd, f. 2010. diurnal cycle of the inter tropical discontinuity over west africa analysed by remote sensing and mesoscale modelling. quarterly journal of the royal meteorological society,136(s1), 92–106. doi: 10.1002/qj.435 riehl, h. 1965. an introduction to the atmosphere (international student ed.). mcgrawhill book company ltd., tokyo rodenhuis, d. 2004. adverse weather and air traffic delays.11th conference on aviation range and aerospace. online available at https://ams.confex.com/ams/pdfpapers/81938.pdf stringer, e.t. (ed) 1989. foundations of climatology. an introduction to physical, dynamic synoptic and geographical climatology. surjeet publications, delhi schaefer, l.,millner, d. 2001. flight delay propagation analysis with the detailed policy assessment tool. 2001 ieee international conference on systems, man and cybernetics. e-systems and e-man for cybernetics in cyberspace (cat.no.01ch37236) 2, 1299-1303. doi: 10.1109/icsmc.2001.973100. smith, k. 1975. principle of applied climatology. mcgraw hill company ltd., uk waitz, i., townsend,j., cutcher-gershenfeld,j., greitzer,e., kerrebrock, j. 2004. aviation and the environment: a national vision statement, framework for goals and recommended actions, 55 p. weli, v.e., ifediba, u.e. 2014. poor weather conditions and flight operations: implications for air transport hazard management in nigeria. ethiopian journal of environmental studies & management 7, 235–243. doi: 10.4314/ejesm.v7i3.2 https://ams.confex.com/ams/pdfpapers/81938.pdf introduction study area methods results and discussions relationship among weather parameters in the study area impact of weather parameters on flight disruption in the study area projection of weather parameters from 2005 to 2035 conclusion references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iii. no. 1-4. pp. 31-40 creating excess water inundation maps by sub-pixel classification of medium resolution satellite images mucsi, l. 1 – henits, l. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract excess water frequency factor, which indicates the number of inundations in the area under study within a certain period of time, is the most dynamic variable among the parameters applied in the complex methodology of excess water hazard mapping. creating excess water inundation maps, representing the situation in the most realistic way, was hitherto a critical moment in excess water hazard mapping. instead of field measurements, since the database of landsat satellite images became accessible in 2009, it is possible to process satellite images taken from the year 1985, with using new, non-traditional methods different from the pixel-based classification. these methods are mainly sub-pixel based classifications and they are applied principally on images taken in periods of extended excess water inundation, under clear weather conditions. in our research project, medium-scale mapping was supported principally by hand-held or mounted multispectral (the bands of visible and infrared light) digital aerial photography. the photo-taking process, depending on the actual meteorological conditions, can be flexibly accomplished in the most extended inundation period, thus it is possible to create excess water maps at the scale of 1:10000. introduction excess water frequency factor, which indicates the number of inundations in the area under study within a certain period of time, is the most dynamic variable among the parameters applied in the complex methodology of excess water hazard mapping (pálfai et al., 2004). creating excess water inundation maps, representing the situation in the most realistic way, was hitherto a critical moment in excess water hazard mapping, since the creation of an excess water map via traditional methods and field survey is time-consuming and contains several possibilities for committing errors (licskó b., 2009). one of the major problems regarding field mapping is that the determination of the shape of an extended excess water area is uncertain from a close-to-surface point, owing to the low angle of vision. it is also difficult to determine the extension of the patches by walking round their boundary using kinematic gps. this method gives particularly indefinite results, because there is a continuous transition between the open water surface, the slightly saturated soil and the dry soil, therefore their classification is problematic. while mapping excess water inundation, efforts should be made to cover a large area, and to create largescale thematic maps in a cost effective way. this way, not only the open water surfaces, but also the transitional areas could be mapped. large-scale mapping is supported principally by hand-held or mounted multispectral (the bands of visible and infrared light) digital aerial photography. the photo-taking process, depending on the actual meteorological conditions, can be flexibly accomplished in the most extended inundation period, thus it is possible to create excess water maps at the scale of 1:10000 (licskó b., 2009). however, the survey of vast areas is expensive and requires considerable postprocessing. the mapping of excess water inundation is more economical if the inundation map derives from remote sensing data covering vast areas. excess water inundation maps based on satellite images have been created by the institute of geodesy, cartography and remote sensing (fömi) since 1998. a significant number of maps were created in the years 1999 and 2000, when the inundation was very extended (csornai g. et al., 2000). by means of 0.1 ha resolution thematic excess water maps derived from high-resolution satellite images, not only the open excess water surfaces could be detected and delineated, but also the vegetation in water and the highly saturated soil, which is very destructive to agricultural cultivation. during the pixel-based classification of satellite images taken by the sensors of the applied spot, landsat and irs-1c/1d liss-iii satellites, the determination of the sample areas might run into difficulties as the great number of the spectrally heterogeneous pixels might cause inaccuracy concerning the classification of the transitional areas. in case of satellites revolving in a sun-synchronous orbit, optical satellite images are taken at a welldetermined point in time, however, in these spectral bands cloud cover frequently inhibits image-taking. thus, the images of microwave imaging sensors (envisat, meris, asar, radarsat and ers) are effectively applicable for flood and excess water mapping, as well as in operative works (csekő á., 2003). however, by excess water maps based on radar data only the open water surfaces and the saturated soil areas could be delineated. regarding the images of the year 2000, the radar data by themselves were limitedly suitable for high-resolution excess water mapping, however, they complete the data derived from the optical systems well. since the landsat image database became accessible in 2009, it is possible to process satellite images taken from the year 1985, with using new, nontraditional methods different from the pixel-based classi32 mucsi, l. – henits, l. joeg iii/1-4 fication. these methods are mainly sub-pixel based classifications and they are applied principally on images taken in periods of extended excess water inundation, under clear weather conditions. the study area the area under study is situated in the south-eastern part of the great hungarian plain, in the vicinity of the settlement székkutas. regarding land use, it is characterized by agricultural lands and protected areas belonging to the körös-maros national park. the designated study area is 86 km 2 and is on the boundary of csongrád and békés counties. in terms of excess water hazard, it belongs to the ‘medium hazard’ category (pálfai i. et al., 2004). the relief differences are minimal; the elevation values are between 81 m and 89 m. data applied and their preparation for processing during the survey, two years characterised by excess water inundation were chosen and one image taken in each year respectively have been analysed. excess water inundation was considerable in the year 1986, while it was extreme in the year 2000 (pálfai i., 2006). in these two years satellite images taken in early spring and early summer were selected, which were not disturbed by clouds. the time of the image-taking was as near to the period of the largest excess water inundation as possible. data were downloaded from the web database (http://glovis.usgs.gov) of the u. s. geological survey (usgs). the area under study was also covered by the medium resolution images of the satellites landsat-5 and landsat-7, the catalogue numbers of which are 186/028 and 187/028. thus, more images of the area became available and their time resolution was not only 16 days, but also 7 and 9 days. a landsat-5 tm image (row 187/coloumn 28) taken on 16 th april 1986 and a landsat-7 etm+ image (row 186/coloumn 28) taken on 23 rd april 2000 were selected, both of which were transformed to utm projection system (wgs 84, zone 34). via atmospheric correction, the intensity values of the landsat-5 tm and landsat-7 etm+ were transformed to reflectance values using an erdas imagine model (chavez p. s., 1996; chander g.-markham b. l., 2003). to carry out accuracy estimation, the one-meter resolution colour infrared aerial photographs taken on 23 rd april 2000 were available as reference data. in addition the digital database provided by the field survey of the directorate for environmental protection and water management of lower tisza district (atikövizig) was also applied, which includes the patches of excess water in the inundated areas for the years characterized by inundation. methods spectral mixture analysis the significant advantages of the medium resolution (30 m) tm and etm+ images of landsat satellites revolving in a sun-synchronous orbit are, that they are multispectral images covering vast areas (185*185 km) and they can be transformed with high accuracy to medium scale (approx. 1:100000) land cover maps by traditional pixel-based classification. however, their disadvantage is, that if the reflectance features of the area change on a greater scale in the space (the smallest elements, patches of the landscape pattern are smaller), than the spatial fig. 1 the area under study joeg iii/1-4 creating excess water inundation maps by sub-pixel classification of medium resolution satellite images 33 resolution of the satellite image, numerous so-called spectrally mixed pixels can be found in the image. one of the basic problems of excess water mapping is that the open water surfaces might be relatively small in area, therefore these surfaces, as well as the soil surfaces in the transitional areas and the areas covered by vegetation are difficult to classify owing to the numerous spectrally mixed pixels. for the classification of the spectrally mixed pixels the so-called spectral mixture analysis method was developed (roberts et al., 1998). the aim of spectral mixture analysis (sma) is to determine the spatial ratio of the spectrally homogeneous land cover types, the so-called endmembers, within a pixel. each endmember specifies an unmixed, pure land cover type. the linear spectral mixture analysis (lsma) is the improvement of the sma method, by which the ratio of land cover types can be determined by using minimum two, in case of an ltm picture six, endmembers. in order to be able to solve the linear system of equations (1), the number of the endmembers has to be less than the number of the spectral bands of the image. (1) bbi n i ib rfr    , 1 rb: the reflectance value of the image in band b; n: the number of endmembers; fi: the ratio factor of endmember i; rib: the reflectance value of the i th endmember in band b; εb: residual error. the sum of the ratio factors of the endmembers equals 1 in every pixel and fi ≥ 0. (2) 1 1 ,   n k kif the suitability of the model can be determined on the basis of the εb residual error or on the basis of the value of the root mean square error (rmse) for each band of the image. (3) n rmse n i i   1 2  the endmembers are usually selected from the different bands of the satellite images or 2d scatter plots worked out from the bands (rashed t. et al., 2001). by principal component analysis (pca), the endmembers are easier to determine, since it assembles almost 90 % of the data variance into the first two or three bands and reduces the correlation between the bands to a minimum (smith m. o. et al., 1985). the other frequently applied transformation, which is also applied in this present research, is the minimum noise fraction (mnf) method. it consists of two main steps: (1) in the first step the noise fractions of the database are decorrelated and rescaled on the basis of an estimated noise covariance matrix and transformed data is provided, in which the noise has unit variance and there is no correlation between the bands; (2) in the second step a traditional pca is carried out (green a. a. et al., 1988). the pixel purity index (ppi), that selects the spectrally most pure (extreme) pixels from multispectral or hyperspectral images, was also applied to specify the endmembers. employing iterative methods, the ppi creates n-dimensional spectral spaces on randomly chosen unit vectors. this procedure determines the extreme pixels (those that are at the end of the unit vector) in each projection, and records how many times the given pixel was specified as extreme. the value of each pixel in the resulting image is equal to this number (broadman j. w. et al., 1994). in the first step, mnf images were created for the landsat tm image taken on 16 th april 1986, which resulted in another 6 bands. the information content of the images is continuously decreasing after one another, thus the first three bands contain 89.5% of the total information content. the last bands predominantly contain only noise. the mnf images were used as input data for the ppi calculation, during which process the extreme pixels were defined by the algorithm after 1000 repetition. on the basis of the first three mnf images and the resulting image of the ppi, three endmembers were defined for the linear spectral mixture: (1) the water surfaces, (2) the vegetation, and (3) the soil. these endmembers were pointed out in the spectral space formed by the first three mnf-bands and were detected at the margins and peaks of the 2d scatter plot. fig. 2 the reflectance curves of soil, vegetation and water surfaces 34 mucsi, l. – henits, l. joeg iii/1-4 defining the land cover ratio of the pixels the outcomes of the lsma are the maps showing the ratio of endmembers (soil, vegetation and water) within a pixel. the three maps represent the spatial distribution of the aforementioned land cover types for each pixel. the value of the pixels varies between 0 and 1. if the value equals 1, the ratio of a certain land cover type within the pixel is 100 % (fig. 3). on the gray-scale ratio map of the soil fractions (fig. 3a), the open soil surfaces, are marked with light grey colour, where their ratio is 80-100%. the ratio of vegetation varies between 70 and 100 % on the arable lands, grasslands and pastures (fig. 3b). the open areas covered with excess water are marked with white and light grey colours on the grayscale ratio map of water surfaces (fig. 4) where the ratio of the water covered surface is about 70-100 % within a pixel. the lake fehér near to the settlement kardoskút stretches along as a light grey patch on the south-eastern part of the area. furthermore the excess water in abandoned riverbeds and on arable lands also has high fractional values on the ratio maps. the grey coloured territories are wet soils (saturated soils) and vegetation in water, where the ratio of surface water varies between 30 and 70 %. similarly, maps representing the land cover ratio within the pixels were created based on the landsat etm+ images taken on 23 rd april 2000 (fig. 5). by the analysis of the ratio maps of the water surfaces, the extent of inundation at the two dates can be examined, the total area covered with excess water can be determined and the spatial pattern of the patches of excess water can be compared. fig. 4 the ratio map of water surfaces based on the landsat tm image taken on 16 th april 1986. 5. results and accuracy estimation the classification of land cover ratio maps by using supervised classification a supervised classification was carried out on the 3-band image (1: soil, 2: vegetation, 3: water ratio map), which was the result of the lsma. based on the three endmembers seven classes were created. three of the fig.3 the ratio map of (a) the soil and (b) the vegetation based on the landsat tm image taken on 16 th april 1986. joeg iii/1-4 creating excess water inundation maps by sub-pixel classification of medium resolution satellite images 35 seven classes mainly contain one land cover type, another three classes contain two land cover types and there is one more class that includes all the three land cover types nearly in equal proportion. when the study area was selected, the upper and lower limits of soil, vegetation and open water surfaces were defined. on the basis of this, the following seven classes were defined: (1) open water surfaces, (2) vegetation, (3) open soil surfaces, (4) saturated soil, (5) vegetation in water, (6) soils covered with vegetation and (7) other. the classes are represented in a triangle diagram (fig. 6). during the supervised classification the parallelepiped decision rule was applied. in case of overlapped areas, the certain pixels were assigned to one of the classes by using the minimum distance method. similarly, the supervised classification was carried out on the landsat etm+ image taken on 23 rd april 2000, which resulted in a thematic map with the same 7 classes. the water covered surfaces marked with black colour, the saturated soils and the wet soils can be easily distinguished on the map (fig. 7-8). fig.6 the triangle diagram representing the seven land cover types fig. 5 the ratio maps of land cover types based on the landsat etm+ image taken on 23 rd april 2000. a) soil, b) vegetation, c) water surfaces lower_1 upper_1 lower_2 upper_2 lower_3 upper_3 lower_4 upper_4 soil 0% 27.5% 0% 27.5% 50% 100% 25% 75% vegetation 0% 27.5% 60% 100% 0% 30% 0% 25% water 50% 100% 0% 27.5% 0% 30% 25% 72.5% lower_5 upper_5 lower_6 upper_6 lower_7 upper_7 soil 0% 25% 25% 75% 25% 50% vegetation 27.5% 75% 30% 70% 25% 50% water 20% 70% 0% 25% 25% 50% table 1 the upper and lower limits of the land cover types according to the endmembers 36 mucsi, l. – henits, l. joeg iii/1-4 by comparing the open water surface classes of the two examined dates, the location of the patches of excess water and the total extent of excess water coverage can be defined (fig 9). it can be concluded that the patches of excess water occupy similar locations on the two images, however, there is a difference regarding their extension. the total surface of the patches was 1.52 km 2 in 1986, a year characterised by considerable excess water inundation and it was 2.63 km 2 in 2000, a year characterised by extreme excess water inundation. fig. 7 thematic map based on the endmember ratios of the landsat tm satellite image taken on 16 th .april 1986. (a) székkutas, (b) lake fehér, (1) open water surfaces, (2) vegetation, (3) open soil surfaces, (4) saturated soil(5) vegetation in water (6) soils covered with vegetation, (7) other fig. 8 thematic map based on the endmember ratios of the landsat etm+ satellite image taken on 23 rd april 2000. (a) székkutas, (b) lake fehér, (1) open water surfaces, (2) vegetation, (3) open soil surfaces, (4) saturated soil, (5) vegetation in water, (6) soils covered with vegetation, (7) other joeg iii/1-4 creating excess water inundation maps by sub-pixel classification of medium resolution satellite images 37 accuracy estimation in the first step the results of the classification were compared with the data produced by the field surveys of the directorate for environmental protection and water management of lower-tisza district (atikövizig). our classes of the open water surfaces, the saturated soil and the inundated vegetation were compared with the excess water polygons as references (fig. 10). on the basis of the comparison it can be concluded that due to their smaller scale, the field surveys are less detailed. there are some patches of excess water on the satellite images that can be detected without any image processing method, but they are in areas that are difficult to approach, hard to walk round, thus these patches are missing from the results of the field surveys. the classification based on satellite images is also favourable, as this way the saturated soils can be differentiated from the vegetation in water, while field surveys do not produce such descriptive data. other available data that can be used as reference to estimate the accuracy of the classification are the aerial photographs taken of the tiszántúl, in the vicinity of székkutas on 23 rd march 2000 (fig. 11). although the photographs with 1 m geometrical resolution are appropriate for the visual determination of the land cover types, the precise separation and classification of certain water surfaces on the 3 band photos are hard to carry out with automatic image processing methods. fig. 10 the comparison of the patches of excess water of the three classes of the thematic layer and the field survey (a) székkutas, (b) lake fehér, (1) open water surfaces, (2) saturated soils, (3) vegetation in water in order to prove the importance of the smaclassification, the created thematic layer was compared with the results of a traditional pixel-based classification. isodata classification was carried out on the landsat etm+ 6 band image taken on 23 rd april 2000 (fig. 12), during which process 7 output classes were set. subsequently the 7 land cover classes of the thematic layer were compared with the adequate classes of the isodata clustering by using the cross-tabulation method (table 2). fig. 9 the comparison of the patches of excess water on the images taken on 16 th april 1986 (a) and 23 rd april 2000 (b) (1) lake fehér (2) open water patches 38 mucsi, l. – henits, l. joeg iii/1-4 fig. 11 the aerial photograph (a) and the polygons of the certain classes: (b) open water surface, (c) wet (saturated) soil (d) vegetation in water fig. 12 images based on the isodata classification (a) and the sma-image classification (b) (1) open water surfaces, (2) vegetation, (3) open soil surfaces, (4) saturated soil, (5) vegetation in water, (6) soil covered with vegetation, (7) other joeg iii/1-4 creating excess water inundation maps by sub-pixel classification of medium resolution satellite images 39 on the basis of these, the open water surface class of the isodata classification shows a 67.3% concordance with the water surfaces gained following the sma classification. furthermore, 22.4% and the 9.6% of the open water surface class of the isodata classification have been classified as vegetation in water and as saturated soils, respectively. the class of vegetation shows a 41.8% concordance with the sma classification, however, 54% have been classified as vegetation in water. the soil surfaces show 92.5% concordance. there has been a 59.6% and 66% concordance regarding the wet (saturated) soil and the vegetation in water, respectively. 6. conclusions on the basis of our research it can be concluded that by using a sub-pixel based classification, the medium resolution satellite images are suitable for mapping excess water. the satellite images being available since the mid-1980s provide an opportunity to create excess water hazard maps. the classes of the thematic maps created by the linear spectral mixture analysis are able to provide more detailed results than the traditional pixel-based classifications. the excess water patches of the earlier field surveys are precisely identifiable and by the help of the applied methods the creation of these maps can be made automatic. acknowledgement the present research was financially supported by the economic operative program (gop) references boardman j. w. 1994. geometric mixture analysis of imaging spectrometry data, proc. int. geoscience and remote sensing symp., vol. 4, pp. 2369-2371 chander g. – markham b. l. revised landsat-5 tm radiometric calibration procedures, and post-calibration dynamic ranges, ieee transactions on geoscience and remote sensing 41/11 (2003): 2674–2677 chavez p.s. jr. image-based atmospheric corrections – revisited and improved. photogrammetric engineering and remote sensing 62/9 (1996): 1025-1036 csekő á. 2003. árvízés belvízfelmérés radar felvételekkel [floodand excess water mapping based on radar images] geodézia és kartográfia, 55/2 (2003): 16-22 csornai g. – lelkes m. – nádor g. – wirnhardt cs. operatív árvízés belvízmonitoring távérzékeléssel. [operative monitoring of floods and excess water based on remote sensing] geodézia és kartográfia 52/5 (2000): 6-12 green a. a. – berman m. – switzer p. – craig m. d. a transformation for ordering multispectral data in terms of image quality with implications for noise removal. ieee transactions on geoscience and remote sensing 26 (1988): 65-74 licskó b. 2009 belvizek légi felmérésének tapasztalatai, [the experiences of the aerial photography of excess water] magyar hidrológiai társaság xxvii. országos vándorgyűlés, baja 2009. http://www.hidrologia.hu/vandorgyules/27/dolgozatok/4szek cio.html pálfai i. belvízgyakoriság és belvízkárok magyarországon [the frequency of excess water events and the damages caused in hungary]. hidrológiai közlöny 86/5 (2006): 25-26 pálfai i. – bozán cs. – herceg á. – kozák p. – körösparti j. – kuti l. – pásztor l. 2004. komplex belvíz-veszélyeztetettségi mutató (kbm) és csongrád megye ez alapján szerkesztett belvíz-veszélyeztetettségi térképe, [mapping of excess water hazard in csongrád county based on the complex excess water hazard index] ii. magyar földrajzi konferencia. szeged, 2004. szeptember 2-4. isbn 963 482 687 3 rashed t. – weeks j. r. – gallada m. s. revealing the anatomy of cities through spectral mixture analysis of multispectral satellite imagery: a case study of the greater cairo region, egypt. geocarto international 16/4 (2001): 5-15 rakonczai j.  mucsi l.  szatmári j.  kovács f.  csató sz. 2001. a belvizes területek elhatárolásának módszertani lehetőségei. [methodological possibilities for mapping excess water areas] in: a magyar földrajzi konferencia tudományos közleményei cd. isbn 9634825443. szeged isodata classes 1 2 3 4 5 6 7 s m a im a g e c la ss e s open water surfaces 67.3% 0.5% 0.4% 0.1% vegetation 41.8% 0.1% open soil surfaces 0.1% 0.2% 92.5% 7.2% 0.3% 3.2% 92.0% saturated soil 9.6% 6.6% 59.6% 1.4% 4.4% inundated vegetation 22.4% 54.0% 3.0% 66.0% 0.5% soil covered with vegetation 3.2% 0.8% 0.3% 10.8% 53.0% 3.1% other 0.7% 0.1% 0.1% 29.5% 22.7% 41.9% 0.5% table 2 the comparison of the isodata classification and the sma-image classification using the cross-tabulation method http://www.hidrologia.hu/vandorgyules/27/dolgozatok/4szekcio.html http://www.hidrologia.hu/vandorgyules/27/dolgozatok/4szekcio.html 40 mucsi, l. – henits, l. joeg iii/1-4 roberts d. a. − gardner m. − church r. − ustin s. − scheer g. − green r. o. mapping chaparral in the santa monica mountains using multiple endmember spectral mixture models, remote sensing of environment 65 (1998): 267–279 smith m. o. – johnson p. e. – adams j. j. 1985. quantitative determination of mineral types and abundances from reflectance spectra using principal components analysis, journal of geophysical research 90. c797–c804 land cover change investigation in the southern syrian coastal basins during the past 30-years journal of environmental geography journal of environmental geography 11 (1–2), 45–51. doi: 10.2478/jengeo-2018-0006 issn: 2060-467x land cover change investigation in the southern syrian coastal basins during the past 30-years using landsat remote sensing data muhannad hammad*, lászló mucsi, boudewijn van leeuwen department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: muhannad@geo.u-szeged.hu research article, received 26 february 2018, accepted 5 may 2018 abstract land cover change and deforestation are important global ecosystem hazards. as for syria, the current conflict and the subsequent absence of the forest preservation are main reasons for land cover change. this study aims to investigate the temporal and spatial aspects and trends of the land cover alterations in the southern syrian coastal basins. in this study, land cover maps were m ade from surface reflectance images of landsat-5(tm), landsat-7(etm+) and landsat-8(oli) during may (period of maximum vegetation cover) in 1987, 2002 and 2017. the images were classified into four different thematic classes using the maximum likelihood supervised classification method. the classification results were validated using 160 validation points in 2 017, where overall accuracy was 83.75%. spatial analysis was applied to investigate the land cover change during the period of 30 years for each basin and the whole study area. the results show 262.40 km2 reduction of forest and natural vegetation area during (1987-2017) period, and 72.5% of this reduction occurred during (2002-2017) period due to over-cutting of forest trees as a source of heating by local people, especially during the conflict period. this reduction was particularly high in the alabrash and hseen basins with 76.13 and 79.49 km2 respectively, and was accompanied by major increase of agriculture lands area which is attributed to dam construction in these basins which allowed people to cultivate rural lands for subsistence or to enhance their economic situation. the results of this study must draw the relevant authorities’ attention to preserve the remaining forest area. keywords: basins, land cover, remote sensing, supervised classification, syria introduction the rate of global urbanization is exponentially increasing, causing damage and reducing areas of natural vegetation (hussein et al., 2017; lópez et al., 2001). monitoring changes in land cover and understanding its spatial properties will lead to an accurate and deep understanding of how human activity affects the general ecological state of the environment (stow and chen, 2002; yeh and li, 1999). nevertheless, the deterioration of rural area resources happens quickly, particularly in developing countries (sarma and saikia, 2012). in the mediterranean area, a significant decrease in precipitation amount during the 21st century has been predicted (lelieveld et al., 2012; rohde et al., 2013). the decrease in total annual rainfall is expected to reach 20% by the year 2050 (evans, 2009; gonçalves et al., 2014). as for syria, the current conflict and the subsequent absence of the preservation of forests and natural vegetation by the relevant authorities has played an important negative role in land cover changes (lcc). unfortunately, there is little data available regarding the temporal and spatial aspects of land cover change in the coastal basins, however they would be important because monitoring can helps guiding sustainable development processes especially in rural areas (marh, 1998). sustainable development processes through appropriate basins management must take into consideration the complex interactions between human and biophysical processes which can have harmful far-reaching effects on the environment, as well as on economic activities (panigrahi and goyal, 2017). hence, contemporary basins management as part of regional planning processes should include the security of the landscape and respect for the values of biodiversity (goettle, 2002). remote sensing data has become an effective data source in land cover change monitoring studies. in the course of data processing, several pre-calibrated and evaluated products are generated and can be obtained free of charge (gulácsi and kovács, 2015). remote sensing data and arcgis tools are extensively used to map and analyse land cover changes in river basins. the maximum likelihood classifier (mlc) algorithm of the supervised classification method is applicable to generate land cover maps. basically, this supervised classification algorithm uses training sites of different land cover types for land cover mapping. in general, selecting training sites usually requires considerable time and effort and depends on the experience of the analyst and on the quality of the imagery (aronoff, 2005). moreover, supervised classification requires a priori knowledge about the land cover types in the study area to achieve appropriate training sites and an accurate signature file in order to derive the required land cover maps. this empirical study attempts to identify the spatiotemporal pattern of land cover change for southern coastal river basins in syria as study area using geospatial 46 hammad et al. (2018) data. the main objective is to explore the land cover changes using multi-temporal remote sensing data with the help of geographic information system (gis). specifically, the objectives are: (a) to accurately map the extent of the different land cover types in the whole study area in 1987, 2002 and 2017; (b) to detect and evaluate the land cover changes during the last 30 years; (c) to accurately map the extent of the different land cover types for the four coastal basins in the study area in 1987, 2002 and 2017; (d) to detect and evaluate the land cover changes for each basin in the study period; and (e) to conclude on the main processes and the background reasons of each land cover change pattern. the resulted maps, patterns and trends are useful information for the scientific community and decision makers to support spatial planning and sustainable development in this region. study area the study area is a part of tartous governorate in the southern part of syrian coastal region. it lies between latitudes 34.6438°, 35.0517° and longitudes 35.8494°, 36.3225° covering a total area of 1022 km2. it has four river basins, of which two major river basins are the alabrash river basin and the hseen river basin, and two secondary river basins which are the ghamqa river basin and the mntar river basin (fig. 1). the strong influence of the mediterranean climate brings high annual precipitation of more than 800 mm. the precipitation period is from october to may, and the dry and hot summer period lasts from june to september (abou zakhem and hafez, 2010). elevation data from the shuttle radar topographic mission (srtm) with a spatial resolution of 1 arc-second (approximately 30m at the equator), which can be downloaded free of charge through the united states geological survey official website (usgs, 2017), were used to derive the digital elevation model (dem) and slope maps of the study area. srtm dems data are in geographic decimal degrees (latitude and longitude) projection, with wgs84 horizontal datum and egm96 vertical datum. srtm dems are expected to have a linear vertical absolute height error of less than 16 m, a circular absolute geolocation error of less than 20 m, and a circular relative geolocation error of less than 15 m (farr et al., 2007). the highest elevation in the study area reaches 1093 m above the sea level in the northeast, and the maximum slope value of the study area reaches 56.4° (fig. 2). depending on the values of both the elevation and the slope in the study area, the study area can be divided into three main parts: the mountains, the plateaus and the coastal areas. the mountain area is located in the northeast and east of the study area fig. 1 the location of the study area and its four river basins fig. 2 dem and slope map of the study area land cover change investigation in the southern syrian coastal basins during the past 30-years… 47 between 600 m and 1093 m above the sea level, and has slopes reaching to maximum 56.4 o. the mountains have good natural water resources due to the existence of many springs. in addition to widespread coniferous forests, this part has also small separate settlements with simple rural agricultural lifestyle depending on planting fruit trees and vegetables. the plateaus area is located between 200 m and 600 m above sea level, where the slope decreases and rivers become wider and broad leaved trees and olive trees are abundant, and it forms the wide home for the people in the rural areas of the syrian coastal mountains. in this part, construction works of the biggest dam in this area, the alabrash dam, were started in 1997 and completed in 2000. the irrigation network from this dam helps to irrigate about 10160 hectares of downstream agricultural land (samoudi, 2015). the coastal area is located between 0 m and 200 m above the sea level and has slopes less than 15o. tartous port is the main commercial port in this part and all of the study area. this port is located in the north of the study area in tartous city which is the main and largest c ity in the study area. the akkar plain, a fertile plain with different field crops and greenhouses, can be found in this part too. methods to analyze 30-year of land cover change, landsat surface reflectance (sr) images were ordered free of charge through the usgs official website (usgs 2017) for getting systematic, radiometric, and geometric corrected higher-level products of the study area from landsat-5 tm (thematic mapper), landsat-7 etm+ (enhanced thematic mapper plus) and landsat-8 oli (operational land imager) instruments data with a spatial resolution of 28.5, 30 and 30 m respectively for each vnir multispectral band (table 1). for the longterm assessment process, all landsat images were selected during may to ensure maximum vegetation cover during this reference period. the landsat images were preprocessed individually using arcgis 10.2 software. they were resampled to the same 30-meter resolution, and a subset of the study area from each image was created and re-projected to the same utm 36n zone. after that, 150 well distributed training sites representing all the main land cover classes were selected in each processed landsat image for the supervised classification method which was applied in this study using the common maximum likelihood classifier (mlc) algorithm. this algorithm examines the probability function of a pixel for each of the classes and assigns the pixel to the class with the highest probability (lillesand and kiefer, 1994). four main land cover classes (built-up area, forest and natural vegetation, agriculture lands, and water body) were identified and used to classify the images. furthermore, the overall accuracy of the results of the whole study area and the user accuracy of each class were calculated using an error matrix of the validation data set (congalton, 1991). after that, spatial statistics were calculated for each land cover class and thematic maps for land cover and land cover changes were generated. finally, land cover changes in the whole study area and in each basin during the period of 30 years (1987-2017) were evaluated. table 1 the three landsat images used in this study image acquisition date sensor (imagery id) resolution 26 may 1987 landsat5 tm (p174r36_5t19870526) 28.5 m 11 may 2002 landsat7 etm+ (le71740362002131sgs00) 30 m 28 may 2017 landsat8 oli/tirs (lc81740362017148lgn00) 30 m results the resulted land cover maps for the three years 1987, 2002 and 2017 are demonstrated based on the landsat 5-tm, 7etm+ and 8-oli on figure 3. the land cover maps show that there is no water body class pattern in 1987 land cover map since there was no dam yet in the study area at that year. however, the 1987 land cover map shows that there is a high ratio of the forest and natural vegetation class, in contrast to 2017 land cover map where the higher ratio of agricultural areas and the decrease of forest and natural vegetation areas. all the land cover maps show that most urban areas are located along the sea shore and increase obviously around tartous city and the big towns. fig. 3 land cover maps for 1987, 2002 and 2017 from landsat 5-tm, 7-etm+ and 8-oli images respectively http://www.sciencedirect.com/science/article/pii/s0143622817307968#tbl1 48 hammad et al. (2018) since there was no ancillary data available for 1987 and 2002, visual interpretation on the satellite images was applied to select the training data based on detailed local knowledge of the study area. on the other hand, a total of 160 sampling points were randomly created and used as independent data set for the validation process of the land cover map of 2017 (fig. 4). fig. 4 distribution of validation points on the land cover map of 2017 in order to check the validation points, a field work was executed in 2017. the observed and computed classes at the validation points in the land cover map of 2017 were used to create an accuracy matrix providing the user accuracy for each class and the overall accuracy. user accuracy was calculated by dividing the number of correctly classified pixels in one class by the total number of validation sets in that class (congalton, 1991). the user accuracies of the built-up area and the agriculture lands classes were around 75%, while the user accuracy of the forest and natural vegetation class was 96.80% and for the water body class it was 100%. after that, the overall accuracy was calculated from the average total of all user accuracies. the overall accuracy of land cover map 2017 was 83.75% (table 2). spatial analysis for all land cover maps of 1987, 2002 and 2017 was applied to calculate the different areas of each land cover class in order to investigate alterations in land cover. the area of each land cover class was calculated in square kilometers (table 3), and as the percentage of the total study area (fig. 5). the results were compared to evaluate land cover changes during the 1987-2002 and 2002-2017 periods. the supervised classification result of the 1987 image shows that the largest area is the forest and natural vegetation class containing 651.84 km2, which is 63.75% of the total study area, then it is followed by the agriculture lands class with 346.8 km2 and 33.92% of the total study area. the remaining land cover is the built-up area class with 23.91 km2 and 2.34% of the total study area. also, based on the 2002 supervised classification result, the largest area is the forest and natural vegetation class with 579.79 km2 and 56.70% of the total study area. the agriculture lands cover 407.65 km2 and 39.87% of the total study area, and the built-up area class covers 30.06 km2 and 2.94% of the total study area. the remaining land cover is water body with 5.06 km2 and 0.49% of the total study area. in contrast, the 2017 supervised classification result shows that the largest area is the agriculture lands class with 582.70 km2 and 56.98% of the total study area, followed by the forest and natural vegetation class with 389.44 km2 and 38.08% of the total study area, and the built-up area class with 46.69 km2 and 4.57% of the total study area. the remaining land cover is water body with 3.73 km2 and 0.36% of the total study area. table 3 land cover classes area in 1987, 2002 and 2017 in km2 land cover classes 1987 2002 2017 area (km2) area (km2) area (km2) built-up area 23.91 30.06 46.69 forest & natural vegetation 651.84 579.79 389.44 agriculture lands 346.80 407.65 582.70 water body 0 5.06 3.73 fig. 5 land cover classes area in 1987, 2002 and 2017 in percentage of the total study area table 2 classification accuracies for land cover map 2017 class name class 1 2 3 4 user accuracy validation points built-up area 1 3 0 1 0 75% 4 forest & natural vegetation 2 0 60 2 0 96.80% 62 agriculture lands 3 0 23 70 0 75.30% 93 water body 4 0 0 0 1 100% 1 overall accuracy 83.75% 160 total land cover change investigation in the southern syrian coastal basins during the past 30-years… 49 discussion the study area as a whole is subject to a general decrease of natural vegetation. the largest change in land cover type was the reduction of the forest and natural vegetation class with an amount of loss reaching 262.40 km2 out of 651.84 km2 which is equal to almost 40% of the area of this class, and 25.66% of the total study area. almost 72.5% of this reduction occurred during the 2002-2017 period, and just 27.5% of it occurred during the 19872002 period. this reduction is most likely caused by overcutting of forest trees over time and especially during the recent conflict period and the subsequent absence of the preservation of the forest and natural vegetation. at the same time, the agriculture lands class area increased 235.90 km2 which can be attributed to the attempts of local people to cultivate more land in rural areas for subsistence or to enhance their economic situation. meanwhile, the area of the built-up area class has increased with 22.77 km2 till 2017 which is almost double that of the 1987 area. however, it must be mentioned that the alabrash dam has entered in service in 2000. so, the water body areas here represent the reservoir area in which the storage of the water is related to the annual amount of the rainfall and the irrigation operations from the dam. the forest and natural vegetation class showed the largest land cover change, it is representative of natural vegetation in the study area. therefore, spatial analysis was applied on the land cover changes of this class in order to evaluate the detailed trends of the changes in this class during the two main periods of the study 1987-2002 and 2002-2017 (fig.6). the results show that the forest and natural vegetation class lost 29.03% of its area between 1987 and 2002, while this loss reached 42.66% between 2002 and 2017 (table 5). this increasing value reflects not only the climate change during the second period but also the negative role of the current conflict in syria and the subsequent absence of the preservation of the forests and natural vegetation. land cover change analyses were executed for each basin in the study area and the results show that the alabrash basin has the maximum forest and natural vegetation area decline in percentage relative to the basin area with 30.98%. at the same time, the hseen basin has the maximum forest and natural vegetation area decline in square kilometres with 79.49 km2 reduction. meanwhile, the mntar basin has the minimum forest and natural vegetation area decline in both square kilometres and percentage relative to the basin area with 36.92 km2 and 21.70% respectively. moreover, the major increase of agriculture land area could be seen also in the both alabrash and hseen basins with 67.65 km2 and 77.52 km2 respectively (table 6). this can be attributed to the dam construction processes in these two basins in the late nineties which allowed many local people to cultivate more rural lands to enhance their economic situation or even for subsistence during the current conflict period. this increase of the agricultural land area here at the expense of the forest and natural vegetation area can be considered as a negative change in the ecosystem of the area as it most likely indicates the possibility of the built area growth in a later stage. table 4 the land cover change of the whole study area between 1987 and 2017 land cover classes land cover change 1987-2002 land cover change 2002-2017 land cover change 1987-2017 km2 % km2 % km2 % built-up area 6.14 0.60 16.63 1.62 22.77 2.22 forest & natural vegetation -72.05 -7.04 -190.35 -18.61 -262.40 -25.66 agriculture lands 60.84 5.95 175.05 17.11 235.90 23.06 water body 5.05 0.49 -1.329 -0.13 3.73 0.36 fig. 6 changes of forest & natural vegetation class during the 1987-2002 and 2002-2017 periods 50 hammad et al. (2018) also, the result of land cover change analyses for each basin in the study area shows that the hseen basin has the smallest built-up area increase in both square kilometres and percentage relative to the basin area with 1.53 km2 and 0.42% respectively. while, the mntar basin has the largest built-up area increase in percentage relative to the basin area with a 4.29% increase within the basin. at the same time, the ghamqa basin has the maximum built-up area increase in square kilometres with 8.62 km2 increase within the basin. this increase of the built-up area in these basins is related to the growth of tartous city in addition to the big towns and villages in the study area especially during the last few years after the arrival of large numbers of displaced families who were forced to flee their homes from the interior regions of syria due to the current conflict. so, the attempt of some local people and real estate traders to make benefits from accommodate these families plays a main role in the growth of the construction works in these areas. table 5 patterns of forest & natural vegetation change during the 1987-2002 and 2002-2017 periods patterns of forest & natural vegetation change area in (%) of total forest & natural vegetation class area (1987-2002) area in (%) of total forest & natural vegetation class area (2002-2017) forest & natural vegetation to built-up area 0.73 1.10 forest & natural vegetation to agriculture lands 28.65 41.53 forest & natural vegetation to water body 0.52 0.02 no change 70.07 57.34 table 6 the land cover changes of each basin during the period of study (1987-2017) land cover classes 1987 2017 lcc 1987-2017 area km2 area % area km2 area % change km2 change % alabrash basin (245.77 km2) built-up area 2.98 1.21 8.29 3.37 5.31 2.16 forest & natural vegetation 159.93 65.07 83.79 34.09 -76.13 -30.98 agriculture lands 82.85 33.71 150.50 61.22 67.65 27.51 water body 0 0 3.20 1.30 3.20 1.30 hseen basin (357.82 km2) built-up area 6.98 1.95 8.51 2.38 1.53 0.42 forest & natural vegetation 270.85 75.69 191.36 53.48 -79.49 -22.20 agriculture lands 79.98 22.35 157.50 44.02 77.52 21.67 water body 0 0 0.38 0.10 0.38 0.10 ghamqa basin (248.98 km2) built-up area 10.29 4.13 18.92 7.60 8.62 3.46 forest & natural vegetation 149.00 59.84 79.12 31.78 -69.88 -28.05 agriculture lands 89.68 36.01 150.86 60.60 61.18 24.58 water body 0 0 0 0 0 0 mntar basin (170.03 km2) built-up area 3.65 2.15 10.95 6.44 7.29 4.29 forest & natural vegetation 72.07 42.38 35.15 20.68 -36.92 -21.70 agriculture lands 94.30 55.46 123.83 72.86 29.52 17.40 water body 0 0 0 0 0 0 land cover change investigation in the southern syrian coastal basins during the past 30-years… 51 conclusion this study analyzed the changes in land cover of the southern syrian coastal basins during the last 30 years, based on multi-temporal landsat surface reflectance images from three different dates in 1987, 2002 and 2017. supervised classification method was applied using the common maximum likelihood classifier (mlc) algorithm to classify each landsat image into four land cover classes. spatial analysis on each land cover map of 1987, 2002 and 2017 was applied to calculate the different areas of each land cover class in order to investigate their changes during the study period. the results show that the study area is strongly affected by a general decrease of forest and natural vegetation, especially during the 2002-2017 period, which not only reflects the climate change, but also the negative role of the current conflict in syria. the main reasons for the decrease in the forest and natural vegetation in the study area are over-cutting of forest trees due to the absence of the forest and natural vegetation preservation by the relevant authorities, and also the attempts of local people in this area to cultivate more lands in rural areas either for subsistence or to enhance their economic situation. the results of this study must draw attention of the relevant authorities to put urgent plans to preserve the remaining forest area, and also to put long-term strategies to restore the forest area that has been lost so far within the whole coastal region in general, and within the southern coastal basins in particular. also, more studies on the impact of the war in syria on land cover change as well as on the long-term implications of climate change must be carried out because the exact knowledge of spatial patterns and trends may help guiding sustainable development processes especially in the rural areas. acknowledgements the study was supported by the stipendium hungaricum programme. references abou zakhem, b., hafez, r. 2010. climatic factors controlling chemical and isotopic characteristics of precipitation in syria. hydrological processes 24, 2641–2654. doi: 10.1002/hyp.7646 aronoff, s. 2005. remote sensing for gis managers. illustrated ed. s.l.:esri press. congalton, r.g. 1991. a review of assessing the accuracy of classifications 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(in arabic) sarma, s., saikia, t. 2012. prioritization of sub-watersheds in khanapara–bornihat area of assam–meghalaya (india) based on land use and slope analysis using remote sensing and gis. journal of the indian society of remote sensing 40(3), 435–446. doi: 10.1007/s12524-011-0163-6 stow, d.a., chen, d.m. 2002. sensitivity of multitemporal noaa avhrr data of an urbanizing region to land-use/land-cover changes and misregistration. remote sensing of environment 80(2), 297–307. doi: /10.1016/s0034-4257(01)00311-x usgs, i.w. 2017. srtm dem data and landsat surface reflectance level-2 science products. <https://earthexplorer.usgs.gov/> (accessed 10.07.2017) yeh, a.g.o., li, x. 1999. economic development and agricultural land loss in the pearl river delta, china. habitat international 23(3), 373–390. doi: 10.1016/s0197-3975(99)00013-2 introduction study area methods results discussion conclusion acknowledgements references integrated approach to estimate land use intensity for hungary journal of environmental geography 12 (3–4), 45–52. doi: 10.2478/jengeo-2019-0011 issn 2060-467x integrated approach to estimate land use intensity for hungary gábor mezősi 1*, burghard c. meyer2, teodóra bata1, ferenc kovács1, bálint czúcz3, zsuzsanna ladányi1, viktória blanka1 1department of department of physical geography and geoinformatics, university of szeged, 6722 szeged, egyetem u. 2-6, hungary 2department of physical geography and geoecology, institute of geography, leipzig university, johannisallee 19a, 04103 leipzig, germany 3centre for ecological research, hungarian academy of sciences, alkotmány u. 2-4, 2163 vácrátót, hungary *corresponding author, e-mail: mezosi@geo.u-szeged.hu research article, received 7 october 2019, accepted 30 november 2019 abstract an integrated approach was applied in this article to provide a medium-scale map of land use intensity for hungary. the main goal was to estimate its value by a small set of parameters, which are freely available and have a high resolution. the basis of the evaluation was the corine 2012 dataset, and a matrix method was applied to integrate the ratio of natural/semi-natural vegetation, woody vegetation and the natural capacity index in the assessment to describe the complex approach of land use intensity. the medium level land use intensity map provides information for decision makers/landscape planners on the current status and spatial pattern of anthropogenic impact and indicates those hot-spots where land use intensity is high and should be focused research and management to intervene in order to encourage sustainable land use. 46% of the arable lands in hungary show the most intensive land use. comparing the map with the previously published hemeroby map of hungary, more intensive impact on landscape transformation through human action was found. in agricultural areas both researches agree that the intensity and human activity is really high, and the lowest intensity class is rare in hungary except for mountain regions and protected areas. keywords: intensity, matrix method, corine, naturalness introduction measuring the intensity of changes in land use is one of the key issues considering the assessment of anthropogenic impacts. without investigation, it is understandable that human influences play a key role in intensifying land use (e.g. global growth of settlements and industrial areas). the intensity of land use can be approached from different content and structural aspects (erb et al., 2013). well-known approach is the economic approach, however other attempts to assess the factors driving the intensification of changes (e.g. population, technology), or the anthropogenic and social changes leading to it, are also frequent. lots of one-dimensional indicators are used to determine the extent of intensity e.g. annual crop yield, rotation length, size of forest and uncultivated areas, frequency of sowing, the magnitude of biodiversity, the size of labour and capital per field, annual production of the area, the climate, soil and technique affecting the crop yield (herzog et al., 2006; erb et al., 2012; verbung, 2013). a key issue concerning intensity is how to measure the impacts of anthropogenic effects on a given region. the methods of solution usually depend on the question to be answered, but the systemic character and the complexity of the affected environment cannot be ignored. calculations that include multiple factors into one index are also used to express land use intensity. one such complex index with regard to agricultural utilization is, for example, the ili index (indicators of landuse intensity herzog et al., 2006) which includes the n content and the pesticide use of a unit area; the "r" index signifying the actual yield and the reference yield under the conditions of strictly determined economic and technological factors (dietrich et al., 2012). various landscape indices and irrigation, ploughing and land use change data were also attempted to be combined into another agricultural intensification index with geostatistical methods (culman et al., 2010). according to the logic used, all of these attempts show to what extent anthropogenic activity changes agricultural productivity. similar intensity calculations are also known for non-arable areas, the lui (land use intensity) index is one of them, and it is used for meadows with the data of fertilization, mowing and animal husbandry (blüthgen et al., 2012). whatever method is used to measure the extent of intensity, it heavily depends on the topographic scale, the time scale used, and the studied agricultural activity (temme and verbung, 2011; verbung, 2013). intensity is a concept that encompasses the use, management, and infrastructure of an area, and a lot of different parameters are known to express it. this study attempts a medium-scale estimation of land use intensity for hungary. a matrix concept was applied to estimate the land use intensity based on the ratio of natural areas and woody vegetation, further more naturalness for selected land use types in hungary. 46 mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. study area hungary, having an area of 93 thousand km2, has a basin character where 80 % of the surface elevation is less than 200 m above sea level. about 75 % – more than 6 million ha – is agricultural area: the arable land, the forest area and grassland are 47%, 21% and 8.5 %, respectively. on 70% of the arable lands intensive, and about 30 % extensive agriculture is typical (ángyán et al., 2003). the hungarian basin area is characterized by a medium-scale, intensive arable area divided into parcels with sizes ranging from 1 to10 ha ( van der zanden et al., 2016). nuts2 level assessment is not appropriate to allocate the territorial differences in land use intensity. our evaluation was based on the 2012 corine land cover 2012 (clc 2012) database (available for europe), where out of the 44 land cover classes in hungary 15 were chosen (fig. 1), inc luding agricultural areas (211 non-irrigated arable land, 213 rice fields, 221 vineyards, 222 fruit trees and berry plantations, 231 pastures, 242 complex cultivation patterns, 243 land principally occupied by agriculture, with significant areas of natural vegetation), forest and semi-natural areas (311 broad-leaved forest, 312 coniferous forest, 313 mixed forest, 321 natural grasslands, 324 transitional woodland-shrub, 333 sparsely vegetated areas) and wetlands (411 inland marshes, 412 peat bogs). this resolution of data contributed to a medium-scale evaluation of intensity in land use in hungary. data and methods partial input or output data (or a combination of them) for the present analysis were not applied in this study, but we intended to use an integrated approach. the reason behind it is that the majority of the cited research connected some kind of complexity to the concept of intensity (e.g. newbold et al., 2015). when designing the applied method, it was also necessary to be taken into account that the land use and land cover data available as remote sensing data, mostly used because of efficiency, and cannot be used directly or only to a limited extent to measure intensity changes. among other things, it is due to the fact that it is difficult to detect the intensity of certain surface types, which manifest in the chemical or management characteristics of soils (eckert et al., 2017). the applied data, their source and resolution is presented in table 1 (corine clc data without artificial areas, the boundaries of areas under nature conservation, and the extent of the woody vegetation based on the dominant leaf type, furthermore the natural capacity index). the national protected areas, as well as the natura 2000 sci areas were applied in the article to allocate the natural and semi-natural areas in hungary. the boundaries of the woody vegetation were allocated by the copernicus high resolution layers (hrl) data on dominant leaf type. the applied natural capacity index (nci) essentially expresses the naturalness and size of the spots obtained as a result of the calculation in a size of 36 ha, in a gridded layout (czúcz et al., 2012). in hungary the maximum value is 63 (from 100), which means that the degree of fig. 1 study area with the corine land cover classes (clc 2012) and the combined map of protected areas (natura 2000 sci and national park core areas and buffer zones) mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. 47 naturalness is up to 63% on certain spots. the natural surface of hungary is less than 3.3% (bölöni et al., 2008). when developing the method, we wanted to achieve an integrated approach with fewer, well-explained and generally available parameters. in order to achieve this goal, we used a simple method to identify intensity changes, a method that can identify those patches which exhibit more significant changes on a more detailed scale too, and, therefore, can be analyzed for their effect (kuemmerle et al., 2016). the resulting categories can be compared to lambin et al. (2001) and with van den zanden et al. (2016) and the principles of intensity calculations, as well as with the parameters applied. the workflow of the applied assessment is presented in fig. 2. the first step was to determine of the percentage of natural or semi-natural vegetation cover for each land cover patch (based on the combined map of protected areas maps: natura 2000 sci, the core and buffer zone of the national parks without weighting). as a second step the percentage of woody vegetation cover based on the dominant leaf type hrl product was also assigned to each land cover patch. as step 3, a 5x5 matrix was provided using the ratio of natural vegetation and woody vegetation to all selected clc 2012 patches. using the matrix method, the relationship between natural vegetation and woody land cover was investigated. the naturalness of vegetation and the percentage of forest cover were also grouped into 5-5 clusters. the clusters were evenly distributed (0-3%, 3-25%, 25-50%, 50-75, >75%). thus, the result has become quite uniform, with an intensive anthropogenic use of the area on scale 1-5. as the last step, the refinement of the matrix results was done by the natural capacity index (nci) compiled with field surveys (czúcz et al., 2008, 2012), the results of these detailed recordings at a resolution of 36 ha were used on a 3-kmmesh. nci data was integrated also with the application of an 5x5 matrix. as a result, the produced classes represent the intensity of land use for all corine patches from 1 to 5, where 1 indicates the most intensive land use. fig. 2 workflow of the applied assessment results the ratio of natural and semi-natural vegetation in most agricultural areas (211, 213, 221, 222, 242) is very low (table 2). almost 99% of the patches include less than 3% natural and semi-natural vegetation cover. among agricultural areas, 231 and 243 can be represented with higher ratios of natural or semi-natural vegetation cover, however, still 95% is represented by natural vegetation cover lower than 3%. in this case, however, approx. 2,5% of the corine patches are covered with natural vegetation over 75%. for forests, the ratio of natural and semi-natural vegetation is still low in case of the 311, 312, 313 categories, since these are mostly planted forests. but table 1 the applied datasets in the integrated approach data layers content source date resolution corine land cover agricultural areas, forests, wetlands corine clc 2012 dataset: https://land.copernicus.eu/paneuropean/corine-land-cover/clc-2012 2012 25 ha natura 2000 sci boundaries of protected natural, semi-natural vegetation eea datasets: https://www.eea.europa.eu/data-andmaps/data/natura-9 2017 5 ha national protected areas core and buffer zones of national parks nature conservation information system http://webgis.okir.hu/tir/ 1990s 5 ha dominant leaf type woody vegetation eea copernicus land monitoring service – high resolution layer forest:product specifications document 2018, sentinel evi data 2015 20 m natural capacity index (nci) naturalness czúcz et al. 2008, 2012 2012 36 ha 48 mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. in case of categories 321 and 333 (natural grasslands and sparsely vegetated areas) significant ratio (59, 80%) of the patches are represented with natural and semi-natural vegetation cover over 75%. they are mostly protected areas, only 18-28% of the patches are represented with 0-3% of natural and semi-natural vegetation cover. the extent of 411 and 412 categories are quite small related to all other categories. in more than 50% of their corine patches they are represented with natural and semi-natural vegetation cover less than 3%. the ratio of woody vegetation in most agricultural areas (clc codes: 211, 213, 221, 231, 242) is very low (table 3). 85-99% of the patches include less than 3% woody vegetation cover and 0% of the patches have woody vegetation cover over 75%. only 222 (fruit trees and berry plantations) show somewhat lower values (78%) for the 0-3% category. in this case, all other classes are evenly distributed, approx. 5%. the category 243 shows similar values to 222. among forest areas 311, 312, 313 (mostly planted forests) are characterised by high woody vegetation cover in 74 78%, however, in 13-14% of the corine patches show less woody vegetation cover than 3%. in case of 333, almost all patches have no woody vegetation cover, 411 and 412 are characterised by mostly 25-50% woody vegetation cover. based on the matrix method the relationship between natural vegetation and woody vegetation cover is demonstrated in fig. 3. the results represent an intensive anthropogenic use of the study area , more than 70% cover of the category 1, which indicates intensive land use itself. this coincides with the results so far (e.g. ángyán et al. 2003 ). after step 3 it becomes obvious that the overall picture on land use intensity based only these two parameters is more complex and shows different pattern than the land cover itself. table 2 percentage of corine patches according to the 5 natural and semi-natural vegetation cover classes corine 2012 natural and semi-natural vegetation cover 0-3% 3-25% 25-50% 50-75 % >75 % 211 non-irrigated arable land 98.60 0.70 0.07 0.14 0.49 213 rice fields 96.95 0.00 0.00 0.00 3.05 221 vineyards 99.23 0.10 0.28 0.09 0.30 222 fruit trees and berry plantations 99.62 0.10 0.06 0.00 0.22 231 pastures 95.07 0.61 1.02 0.72 2.58 242 complex cultivation patterns 98.82 0.23 0.16 0.16 0.63 243 land principally occupied by agr. with sign. areas of nat. veg. 95.68 0.32 0.46 0.98 2.56 311 broad-leaved forest 79.58 2.35 4.34 7.21 6.52 312 coniferous forest 81.05 0.36 0.35 0.80 17.44 313 mixed forest 81.53 0.34 0.61 1.20 16.31 321 natural grasslands 28.78 0.15 2.58 9.26 59.24 324 transitional woodland-shrub 89.89 0.48 0.69 0.73 8.20 333 sparsely vegetated areas 18.59 0.00 1.24 0.00 80.17 411 inland marshes 50.59 0.38 0.80 1.53 46.70 412 peat bogs 77.15 7.05 0.12 2.04 13.64 table 3 percentage of corine patches according to the 5 woody vegetation cover classes woody vegetation cover 0-3% 3-25% 25-50% 50-75 % >75 % 211 non-irrigated arable land 98.13 1.79 0.06 0.02 0.01 213 rice fields 99.95 0.05 0.00 0.00 0.00 221 vineyards 94.51 3.87 1.32 0.31 0.00 222 fruit trees and berry plantations 78.85 4.55 4.88 6.76 4.96 231 pastures 90.82 5.92 2.41 0.68 0.16 242 complex cultivation patterns 86.62 7.49 4.71 1.09 0.09 243 land principally occupied by agr. with sign. areas of nat. veg. 71.16 6.33 14.14 6.89 1.47 311 broad-leaved forest 13.05 0.53 0.79 7.21 78.43 312 coniferous forest 13.47 0.29 1.16 9.14 75.94 313 mixed forest 14.73 0.20 0.70 10.16 74.21 321 natural grasslands 95.49 3.31 0.98 0.14 0.08 324 transitional woodland-shrub 41.19 1.97 9.56 20.99 26.30 333 sparsely vegetated areas 99.86 0.14 0.00 0.00 0.00 411 inland marshes 89.09 4.88 3.75 1.72 0.55 412 peat bogs 85.80 9.03 4.19 0.73 0.24 mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. 49 fig. 3 the result map of step3: application of the matrix method to demonstrate the relationship of natural vegetation cover and woody vegetation cover in all selected clc 2012 patches fig. 4 the result map of step 4: landuse intensity map of hungary (1-highest land use intensity; 5-lowest land use intensity) 50 mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. the final land use intensity map, integrating nci datasets, is presented in figure 4. concerning land use intensity, the mountaineus regions of hungary (transdanubian mountains, north hungarian mountains, transdanubian hills) are represented with the lowest land use intensity. the little plain located in nw hungary is mostly charactersed by high land use intensity (class 1), in contrary to the great hungarian plain, where we can found larger patches with medium intensity (or even low). the differences in soil attributes are clearly reflected in the resulted datasets: land use intensity on sandy soils, and saltaffected soils is lower compared to the neighbouring areas. 46% of the arable lands (211) in hungary show the least naturalness, and the lowest ratio of woody vegetation and natural, semi-natural vegetation cover, thus, the most intensive use. it is similar only about 3% of the meadows (231). to show the details of the provided map, a zoom on the area neighbouring szeged is shown in figure 5, with an overlay of the corine codes 211 and 231, as the most frequent land covers of the great plain. this area is a good example of the differences between the different landscapes (here: alluvium, sandland, loess covered areas). discussion and conclusion for many, it is obvious that areas with strong anthropogenic influences, are characterized by ecological consequences such as the growing destruction of plants, a dramatic reduction in desirable biodiversity, an increase in the isolation of vegetation (e.g. in urban areas). in most cases, biodiversity change is mentioned, as it is measurable well and its effects can be analyzed. its environmental expectations are clarified even according to eu standards (natura. 2000). several procedures from various areas are known to measure the intensity of land use. in particular, input and output parameters (e.g. crop yield per unit, n content) or their integrated version are used, thus, e.g. the infrastructural fragmentation index (ifi), the urban fragmentation index (ufi), or the connectivity index (ci) are defined (de montis et al., 2017). the fragmentation of the landscape, which includes the fragmentation of larger units into smaller ones and the typical transformation of intensively used areas, is one of the most significant effects on ecosystem services (jaeger et al., 2016). we primarily attempted to measure the anthropogenic effects for the characterization of landscape diversity which is in connection with the land use intensity. therefore, we compared the regional differences of intensity (fig. 4) with the regional differences of hemeroby (fig. 6, csorba et al. 2018), because they both share the same causes in the background. the hemeroby map by csorba et al. (2018) shows less intensive impact on landscape transformation through human action, than this research. in agricultural areas both researches agree that the intensity and human activity is really high and the lowest intensity is rare in hungary (except for mountain regions and protected areas). more intensive use of cropland, generally determinded by high land use intensity, may affect to varying degrees on environmental parameters. for soil fig. 5 land use intensity map around szeged overlayed wih clc 2012 layers with code 211 and 230 mezősi et al. 2019 / journal of environmental geography 12 (3–4), 45–52. 51 e.g. increase in compaction, structure degradation, or the higher level soil of erosion by water. in the case of vegetation, the decrease in biodiversity, growth of uncultivated areas and abandoned areas. our results indicates those hot-spots where land use intensity is high in regional scale. these areas should be focused regarding research, management and spatial planning too. with management of low-intensity pasture systems, conservation of high-value habitats and their associated biodiversity, it can be identified where and how to intervene in order to encourage sustainable land use. references ángyán, j., balázs, k., podmaniczky, l., skutai, j. 2003. integrated land use zonation system in hungary as a territorial base for agri-environmental program. in: helming, k., wiggering, h. 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europe. agriculture. ecosystems and environment 140, 46–56. doi: 10.1016/j.agee.2010.11.010 van der zanden. e.h. levers. c.. verburg. p.h.. kuemmerle. t. 2016. representing composition. spatial structure and management intensity of european agricultural landscapes: a new typology. landscape and urban planning 150, 36–49. doi: 10.1016/j.landurbplan.2016.02.005 verburg, p.h., tabeau, a., hatna, e. 2013. assessing spatial uncertainties of land allocation using a scenario approach and sensitivity analysis: a study for land use in europe. journal of environmental management 127, 132–144. doi: 10.1016/j.jenvman.2012.08.038 https://www.taylorfrancis.com/books/e/9781482244687/chapters/10.1201%2f9781315372860-34 https://www.taylorfrancis.com/books/e/9781482244687/chapters/10.1201%2f9781315372860-34 http://iopscience.iop.org/journal/1748-9326 https://www.sciencedirect.com/science/article/abs/pii/s0167880900002358?via%3dihub#! https://www.sciencedirect.com/science/article/abs/pii/s0167880900002358?via%3dihub#! https://www.sciencedirect.com/science/article/abs/pii/s0167880900002358?via%3dihub#! introduction study area data and methods results discussion and conclusion references assessment of possible uncertainties arising during the hydromorphological monitoring journal of environmental geography journal of environmental geography 10 (3–4), 27–33. doi: 10.1515/jengeo-2017-0010 issn: 2060-467x assessment of possible uncertainties arising during the hydromorphological monitoring of a sand-bedded large river tamás právetz1*, györgy sipos2, zsuzsanna ladányi2 1middle tisza district water directorate, boldog sándor istván krt. 4, h-5000 szolnok, hungary. 2department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: pravetz@gmail.com research article, received 1 september 2017, accepted 8 november 2017 abstract the riverbed morphology of sand-bedded rivers is dynamically changing as a consequence of quasi continuous bedload transport. in the meantime, the dimension, size and dynamics of developing bedforms is highly depending on the regime of the river and sediment availability, both affected by natural and anthropogenic factors. consequently, the assessment of morphological changes as well as the monitoring of riverbed balance is challenging in such a variable environment. in relation with a general research on the longer term sediment regime of river maros, a fairly large alluvial river in the carpathian basin, the primary aim of the present investigation was to assess uncertainties related to morphological monitoring, i.e. testing the reproducibility of hydromorphological surveys and digital elevation model generation by performing repeated measurements among low water conditions on selected representative sites. surveys were conducted with the combination of an adcp sonar, gps and total station. the most appropriate way of digital elevation modelling (dem) was tested and 30-point kriging was identified to be optimal for comparative analysis. based on the results, several uncertainties may affect the reproducibility of measurements and the volumetric deviation of dem pairs generated. the mean horizontal difference of survey tracks was 3-4 m in case of each site, however this could not explain all the dem deviation. significant riverbed change between measurements could also be excluded as the main factor. finally, it was found that results might be affected greatly by systematic errors arising during motor boat adcp measurements. nevertheless, the observed, normalised and aggregated dem uncertainty (600-360 m3/rkm) is significantly lower than the changes experienced between surveys with a month or longer time lag. consequently, the developed measurement strategy is adequate to monitor long term morphological and sediment balance change on sand bedded large river. keywords: hydromorphological surveying, digital elevation modelling, uncertainty, reproducibility introduction fluvial systems are characterised by a continuous change determined by various direct and indirect controlling variables, affected by natural and anthropogenic processes. one of the key driver of fluvial dynamics is sediment regime, affected by river flow regime, geological background and sediment availability. consequent quality and quantity of sediment will also have a major effect on river morphology and bedform characteristics (schumm, 2005). therefore, if these are surveyed and assessed valuable information can be gathered in turn on the status of the investigated fluvial system (sipos et al., 2012). the surveying and monitoring of the riverbed nevertheless can be highly challenging, since there is a limitation in space and time due to the rapidly changing environment, and in the meantime the execution of the measurements can also have difficulties (sipos, 2006; sipos et al., 2012). a straightforward way of investigating morphological change is to perform consecutive bathymetric measurements on longer sections of a river (laczay, 1968, kiss et al., 2008). hydromorphological measurements aim to reveal and monitor the development and changes of the river bed and they contribute to the analysis of the changes in morphology and dynamics. by generating digital elevation models (dem) based on the measured datasets, volume differences can be determined in a certain time period, thus the bedload balance of the investigated river section can be assessed. several devices can be applied for bathymetric measurements: wading rod, sonar, adcp (acoustic doppler current profiler), total station, rtk gps (real time kinematic gps), photogrammetric imaging, lidar (light detection and ranging; defendi et al., 2010; tiron et al., 2009; gómez et al., 2010; laczay 1968; prónay and törös, 2001). using the measured depth and height data obtained by the different equipments, digital elevation model of the study area can be set up, which serves as a basis for further assessments (kertész, 1991; jordán, 2007). however, its accuracy highly depends on the errors arising during surveying. geodetic and therefore bathymetric measurements can be affected by: random, systematic and gross errors which can occur even simultaneously (detrekői, 1991, wise 2000). random errors are scattered around the true 28 právetz et al. (2017) value, and the average of an infinite number of observations results the true value itself, therefore by increasing the number of measurements this type of error can be reduced. a systematic error distorts all measurements in one direction and by increasing the number of measurements the estimation of the true value will not be improved. a gross error significantly exceeds measurement accuracy, determined by random and systematic errors, it does not occur on a regular basis, and it can be filtered by increasing measurement number (sárközi, 1991; taylor, 1999). consequently, during a riverbed survey it is of key importance to identify systematic and gross errors and to foster the reduction of random error by gathering and averaging more data. it is also worth to have control measurements during surveying, which can be used to estimate uncertainty and reproducibility of the assessments. the main aim of the present investigation was to assess the overall uncertainty related to hydromorphological monitoring on a sand bedded large river. secondarily, an attempt was made to determine the type and significance of errors that may affect the deviations experienced during instantly repeated surveys on the selected sites. consequently, it was possible to decide whether the errors related to the measurement allow the comparison of surveys performed to track longer term changes in morphology. study area river maros is the largest tributary of river tisza having a length of 760 km; the investigated study sites are located along its 175 km long lowland section (fig. 1). the discharge of the river fluctuates considerably: during low water periods it is approximately 20-30 m3/s at the makó gauge station, while at floods 1600 m3/s discharge can also occur (sipos and kiss, 2003). the slope is relatively high in case of the whole lowland section and decreases from 40 cm/km (lipova) to 10 cm/km (deszk) (fig. 1). mean flow velocity is 0.5-1.0 m/s. the river transports a significant amount of bedload, having an annual value of 28 000 t at deszk (bogárdi, 1971). the bedload of the alluvial maros is composed mainly of coarse and medium grainsize sand and a subordinate amount of gravel (csoma, 1975). the river has also a significant amount of suspended sediment, which can reach 8.3 million t/year (bogárdi, 1971). river regulation in the 19-20th centuries greatly affected the river and flood control works caused significant changes (kiss and blanka, 2006): the length of the lowland section decreased from 260 km to 175 km (urdea et al., 2012), furthermore river slope and stream power of the regulated river, transporting huge amount of sediments, increased. sections with bank protection (e.g. downstream from lipova and near makó) slightly changed, more dynamic responses could be observed on sections without additional interventions. the investigated lowland section is characterised as a transition between a braided and a meandering channel pattern. the channel is mostly shallow, and in some places intensive bank and island formation can be observed (sipos, 2004). nowadays the most important human activity on the investigated section is gravel and sand quarrying from the riverbed. the mining activity has been continuous since the 1970s; however, from the 2000s it became even more intensive above arad (urdea et al., 2012). fig. 1 location of the study sites assessment of possible uncertainties arising during the hydromorphological monitoring of … 29 in this study 4 sites were analysed, representing sections with different sediment dynamics as a consequence of in channel quarrying, mostly apparent on the sambateni-cicir section of the river (fig. 1). the first site at lipova is located in a meander upstream of the major sand exploitation on the river. the river bottom is composed of sandy-gravelly sediments. the second site at arad is directly downstream of the excavations. the bed of the river here is highly paved by gravels, sand is carried away in the lack of sediment supply as a consequence of in channel mining. the other two sites at pecica and apátfalva are characterised by coarse and medium sand bedload and dynamic channel processes manifested in the formation of various bar forms and fluvial islands. the length of the investigated sites was between 250 and 500 m. their morphology is similar in the sense that each includes a riffle section and an adjacent pool section. the riffles in each case are a complex of bars and/or islands. the measurements in this study were performed mainly on the riffle sections. methods repeated channel surveying was performed at low-water at each of the 4 sites to estimate the overall uncertainty of measurements. at low water conditions bars were exposed at each site, thus subsurface bathymetric and above surface geodetic measurements were applied together with the exception of the lipova site. the comparability of the surveys can be difficult due to the inaccuracy of crosssection tracking, the differences in data density and the differences in elevation modelling. the temporal difference between the start of the two consecutive surveys was approximately one hour to minimize river bed changes originating from bedload transport. cross-sections were allocated to represent variable morphology within a site and to include both underwater and exposed surfaces if possible. the distance between two cross-sections did not exceed the half of river width. the tracking of crosssections was carried out with trimble juno navigational gps with a spatial accuracy of 2-5 m. for surveying underwater sections a light weight motor boat equipped with a rio grande adcp was used. depth data was recorded at 1.5m in average at the given speed of the boat. to each depth data measured by the adcp, surface coordinates were provided using a topcon rtk gps. this device has high horizontal and vertical measuring accuracy. for surveying the exposed parts of the channel a sokkiaset 650rx total station and a topcon rtk gps were applied. the total station was used where the accuracy of the rtk gps was low, e.g. near the river bank under the trees. at the apátfalva site 10 cross-sections and 5 longitudinal sections, while in case of the other areas 5 cross-sections and 5 longitudinal sections were measured repeatedly (fig. 2). during the remeasurement new gps base station was set up and a new base point was assigned to simulate the difference between consecutive surveys and to include the systematic error related to base correction. fig. 2 datapoints of the first and the repeated survey at the apátfalva site after arranging the raw datasets from the different devices in one spatial data infrastructure, digital elevation models (dem) were set up for all areas and surveys under similar conditions to assess the differences. in case of all study sites and both surveys the same reference level was used to determine the volume deviation of dems. models were generated using linear kriging with varying the number of sampling points used for interpolation. in case of the apátfalva site a tin model was also generated. for making comparisons riverbed elevation maps and volumetric maps with and without distortion correction were generated. sediment volumes were calculated based on the resulted digital elevation models using reference levels determined in our previous studies for the first and the second survey too (sipos et al., 2012; právetz and sipos, 2014). beside volume differences the horizontal discrepancy of repeated measurement tracks was also assessed. for the determination of spatial deviation in a given section a polygon was created using the data points of the two measurements, and polygon area was divided by the length of the section resulting a value representing mean horizontal difference. the mean tracking uncertainty for a site was calculated by averaging crosssectional results. results and discussion assessment of dem deviations the dems generated by tin and kriging at the apátfalva site are presented in figure 3. concerning the general morphological setup and main forms the two models yielded very similar results. if temporal differences are considered the main deviation between the first and second survey appeared on the lower section of the study area: a side bar along the left bank and a smaller depression at the right bank almost disappeared on the second elevation model (fig. 3). both forms were related to areas where data density was limited, therefore interpolation difference could be more significant. noteworthy deviations could be observed concerning the slip face of the main bar form on the upper half of the study area (fig. 3). 30 právetz et al. (2017) although in general tin and kriging yielded similar results, a significant difference was identified between volumetric deviations. concerning the tin models the difference between the two consecutive models was 1400 m3, three times higher compared to the volumetric deviation in case of kriging. when the number of neighbouring sampling points used for the interpolation is varied it is obvious that 5-15 points resulted a much higher (500-700 m3) volumetric difference than 25-35 points (300 m3), and that by extending further the number of sampling points deviation started to increase again (400500 m3) (fig. 4). this pattern can be linked to the spatial organisation of data points, namely that there was a 1-2 m spacing between points along a section and that the distance between cross-sections was 40m in average. consequently, if 25-35 points are included then the interpolation accounts for two neighbouring crosssections and also samples the longitudinal sections. if less points are considered it can happen to areas located close to a section that samples are only taken from that section, as the others get out of the reach of the interpolation. this can be especially problematic in case of cross-sections, since the direction of bedforms has a significant longitudinal component, thus the interpolation can have a higher error. on the other hand, if the number of sampling points is too high, not only the neighbouring crosssections but farther sections can also affect the interpolation, thus deviations between the two models can accumulate. based on the results above, for further comparisons a 30-point kriging was applied for dem generation. consequently, in case of the apátfalva site the value of aggregated dem uncertainty was 300 m3. in other words, if a deviation higher than this is experienced between two surveys, it can truly be assigned for morphological changes and the rearrangement of the riverbed. fig. 4 sediment volume deviations based on the number of points taken into consideration during kriging 250 300 350 400 450 500 550 600 650 700 750 5 10 15 20 25 30 35 40 45 50 55 60 65 v o lu m e d e v ia ti o n ( m 3 ) number of points fig. 3 resulted dems using tin (a, b) and kriging (c, d) at the apátfalva site assessment of possible uncertainties arising during the hydromorphological monitoring of … 31 comparison of site specific dem deviations for the remaining three sites the interpolation method described above was applied for the comparison of consecutive surveys and to determine the aggregate uncertainty of hydromorphological measurements at a given site. in case of the pecica site the dem p air showed the most significant deviation at the left flank of the main side bar. during the first measurement a pronounced protrusion can be observed here (fig. 5 a, b). the deviation is accounted for the difference in the track of longitudinal sections passing the bar form (fig. 6). concerning the arad site volumetric deviation can mostly be related to a depression at the right bank, anyway the dem pair show little difference (fig. 5 c, d). no major difference in dems was observed in case of the lipova si te, which is partly due to the relatively simple morphology of this section (fig. 5 e, f). fig. 5 dem pairs generated by kriging from the repeated surveying of test sites (a, b: pecica; c,d: arad; e, f: lipova) 32 právetz et al. (2017) in order to make site specific dem deviation values comparable, results were normalised to 1 river km (rkm) in case of each site (table 1). the lowest normalised deviation can be observed at apátfalva (600 m3/rkm), while the highest at pecica and lipova (3600 m3/rkm). considering all of the studied sections mean volumetric deviation is 2300 m3/rkm. possible sources of deviation deviations suggested to be derived either from improper tracking of the survey lines, changes of underwater bed forms, or the inaccuracy of the elevation data measured by the different devices. as the surveys were performed using different equipment, it is possible to compare the contribution of different techniques to the overall uncertainty. at sites, where both underwater (adcp) and exposed bar surface (gps, total station) surveys were performed it was obvious that the tracking of survey paths was naturally less accurate if measurements were done from the motorboat (fig. 6). this was especially a problem: 1) when crossing the thalweg, where flow velocity is the highest; 2) at near bar very shallow areas, where navigation is difficult; 3) and along longitudinal sections, where a little oversteering of the boat can lead to significant path leaving. in general, the mean horizontal difference between tracks was 3-4m (table 1). the highest value was experienced at the arad site, surveyed mostly from the boat and being morphologically complex (table 1). the lowest value was received at lipova, where exclusively a boat survey was made, but navigation was much easier as water depth was greater and morphology was less complex. consequently, one would expect that the lowest track difference will result the lowest dem deviation and the opposite if track difference is higher. this is not the case, however, because if mean horizontal track difference and volumetric deviation are plotted against each other no relationship can be observed (fig. 7). dem deviations may also be explained by the assumption that river bottom morphology did change between the two measurements regardless of the short repetition time and low water (low energy) conditions. nevertheless, this explanation is contradicted by the fact that the two downstream sites, with a highly mobile sandy bottom, did not show higher dem deviation than those having a paved and more stable river bottom (table 1). another issue is the accuracy of elevation measurements. the absolute precision of at-a-point sonar data (±10 cm) is naturally lower than rtk gps or total station elevation data (± few cm). on the other hand, as during the repeated measurement the same devices were used at the same sections, the difference at the given high number of sampling points should not be affected by at-a-point precision. fig. 6 horizontal difference of survey tracks in case of the pecica site consequently, as the highest dem deviation is observed at the lipova site, where the riverbed is less mobile, track difference was the lowest and only adcp was used for surveying; it is suggested that a systematic error related to adcp use can be the major source of overall uncertainty. knowing volume difference and the area of the surveyed site it is possible to calculate the mean elevation difference between the dem pairs (table 1). even the largest difference (8.1 cm), experienced in terms of the lipova site is small enough to be easily achieved by a systematic difference in the submerging of the measurement device. finally the average elevation difference of consecutive adcp sonar datapoints was also calculated (table 1). if beside this the proportion of adcp surveyed area is also considered, it is obvious that there can be a considerable systematic error, primarily related to adcp measurements, affecting the dem results (table 1). fig. 7 dem volume difference plotted against mean horizontal track difference table 1 volume and cross-section deviations for uncertainty assessment site dem volumetric deviation (m3) mean deviation of survey tracks (m) mean elevation diff. (cm) mean adcp elevation diff. (cm) proportion of adcp survey area (%) normalised volumetric deviation (m3/rkm) apátfalva 300 3.3 0.4 5.0 37 600 pecica 910 3.4 3.6 11.2 62 3640 arad 307 4.0 1.3 2.9 72 1460 lipova 1307 3.1 8.1 11.4 100 3630 assessment of possible uncertainties arising during the hydromorphological monitoring of … 33 conclusion in this paper measurement and evaluation uncertainty was assessed using repeated measurements on representative sections of river maros. after generating dems with different interpolation methods and settings 30-point kriging was considered to be optimal for further comparative analysis of consecutive surveys. several uncertainties were identified in relation with surveying, which may affect the reproducibility of measurements and the final difference in dem pairs generated. after a detailed comparison of sites, the role of these could be qualitatively and quantitatively assessed. the mean horizontal difference of survey tracks, derived from rtk gps measurements, was 3-4 m in case of each site, which is in correspondence to the accuracy of the navigational gps (2-5m) used for tracking the previously appointed survey path, thus better values can hardly be expected. tracking is highly affected by navigational problems in shallow water and at the thalweg. however, if the result of each site is considered this uncertainty will not explain all the deviations experienced in the dem pairs, since the largest deviation was observed where tracking was the most accurate (lipova site). at a point difference in measurement precision and riverbed change were considered to be less significant in affecting the overall uncertainty experienced. therefore, we suggest that systematic errors related to the use of adcp can be the most significant source of error during consecutive surveys. a few cm difference in the submerging of the device under water can result the same order of magnitude deviation as experienced during the uncertainty assessment. therefore, it is strongly advised that the adcp or sonar has to be mounted identically during consecutive measurements, weight distribution in the boat has to be balanced, and surveying speed preferentially should also be of similar throughout the monitoring activity. the calculated and normalised volumetric dem deviation at the different sites ranged between 600 and 3600 m3/rkm, an average value of 2300 m3/rkm can be regarded as the overall uncertainty of surveys at the present environment and measurement setting. this is significantly lower than deviations experienced if measurements with a month or longer time lag are compared (právetz and sipos, 2014). as a result, the here applied survey strategy is adequate for monitoring longer term changes of the river bed of river maros. acknowledgements this research was supported by the following projects of the european regional development fund: huro/0901/266/2.2.2 and husrb/1602/11/0057. references bogárdi, j. 1971. vízfolyások hordalékszállítása. akadémiai kiadó, budapest. (in hungarian) csoma, j. 1975. a maros hidrográfiája. in: vízrajzi atlasz sorozat 19 maros. vituki, budapest; 4–12. (in hungarian) defendi, v., kovacevic, v., arena, f., zaggia, l. 2010. estimating sediment transport from acoustic measurements in the venice lagoon inlets. continental shelf research 30 (8), 883–893. doi: 10.1016/j.csr.2009.12.004 detrekői, á. 1991 kiegyenlítő számítások, tankönyvkiadó, budapest. (in hungarian) fryirs, k.a., brierley, g.j., preston, j.n., kasai, m. 2007. buffers, barriers and blankets: the (dis)connectivity of catchment-scale sediment cascades. catena 70, 49–67. doi: 10.1016/j.catena.2006.07.007 gómez, a. e., diana, g. c., jorge, o. p. 2010. sand transport on an estuarine submarine dune field. geomorphology 121, 257–265. doi: j.geomorph.2010.04.022 jordán, gy. 2007. digital terrain analysis in a gis environment, in: peckham r., jordan gy. (szerk.) digital elevation modelling. development and applications in a policy support environment, 1–43. kertész, á. 1991. természetföldrajzi modellezés, a digitális domborzatmodellezés, in: mezősi g. (szerk.) a mikroszámítógépes módszerek használata a természetföldrajzban, jate jegyzet, szeged (in hungarian) kiss, t., blanka, v. 2006: kanyarulatfejlődés vizsgálata a maros alsó szakaszán. hidrológiai közlöny 86 (4), 19–22. (in hungarian) kiss, t., fiala, k., sipos, gy. 2008. a terepi hordalékhozam-mérő eszközök és módszerek, i. (hagyományos eszközök és a hazai gyakorlat). hidrológiai közlöny 88, 58–61. (in hungarian) kondolf, g.m. 1997 hungry water: effects of dams and gravel mining on river channels. environmental management 21 (4), 533–551. doi: 10.1007/s002679900048 laczay, i. 1968. a cikolaszigeti mellékágrendszer mederváltozásának vizsgálata. vízügyi közlemények 50(2), 245–255. (in hungarian) právetz, t., sipos, gy. 2014. mederanyag egyenleg változásának vizsgálata hidromorfológiai felmérések segítségével a maros síksági szakaszán. hidrológiai közlöny 94 (2), 35–40. (in hungarian) prónay, zs., törös, e. 2001. szonár mérések hidrogeológiai alkalmazásai, in: mht xix. vándorgyűlés. (in hungarian) rakonczai, j. 2008 globális környezeti kihívásaink. universitas szeged kiadó, szeged. (in hungarian) schumm, s. 2005. river variability and complexity. cambridge university press. p. 220. sárközy, f. 1991.térinformatika, bme, http://www.agt.bme.hu/tutor_h/terinfor/tbev.htm. (in hungarian) sipos, gy. 2004. medermintázat és zátonyképződés homokos medrű síksági folyószakaszon (maros 31-50 fkm), geográfus doktoranduszok viii. országos konferenciája, szeged, 2004 szeptember 4-5. (in hungarian) sipos, gy. 2006. a meder dinamikájának vizsgálata a maros magyarországi szakaszán doktori (phd) értekezés, földtudományok doktori iskola, szeged. (in hungarian) sipos, gy., kiss, t. 2003. szigetképződés és –fejlődés a maros határszakaszán, vízügyi közlemények 85 (3), 477–498. (in hungarian) sipos, gy., právetz, t., katona, o., florina, a., timofte, f., onaca, a., kiss, t., kovács, f. 2012. a folyamatosan változó maros mureşul, un râu mereu în schimbare the ever changing river. in a maros folyó múltja, jelene, jövője, szegedi tudományegyetem természeti földrajzi és geoinformatikai tanszék, szeged (futumar, isbn 978-963-306-213-5) taylor, j. r. 1999. an introduction to error analysis: the study of uncertainties in physical measurements. university science books. p. 94, §4.1. tiron, l. j., jérôme, le c., mireille, p., nicolae, p., guillaume, r., guillaume, d., philippe, d. 2009. flow and sediment processes in a cutoff meander of the danube delta during episodic flooding. geomorphology 106, 186–197. doi: 10.1016/j.geomorph.2008.10.016 urdea, p., sipos, gy., kiss, t., onaca, a. 2012. a maros, in: sipos gy. (szerk.) a maros folyó múltja, jelene, jövője. szegedi tudományegyetem, természeti földrajzi és geoinformatikai tanszék, szeged (in hungarian) wise, s.m. 2000. assessing the quality for hydrological applications of digital elevation models derived from contours. hydrological processes 14 (11-12), 1909–1929. doi: 10.1002/10991085(20000815/30)14:11/12<1909::aid-hyp45>3.0.co;2-6 http://www.agt.bme.hu/tutor_h/terinfor/tbev.htm https://books.google.com/books?id=gifqczub80oc&pg=pa94 https://books.google.com/books?id=gifqczub80oc&pg=pa94 introduction study area methods results and discussion assessment of dem deviations comparison of site specific dem deviations possible sources of deviation conclusion acknowledgements references assessing the immediate effect of covid-19 lockdown on air quality: a case study of delhi, india journal of environmental geography 13 (3–4), 27–33. doi: 10.2478/jengeo-2020-0009 issn 2060-467x assessing the immediate effect of covid-19 lockdown on air quality: a case study of delhi, india ankit sikarwar¹*, ritu rani¹ ¹department of development studies, international institute for population sciences, mumbai, maharashtra 400088, india *corresponding author, e-mail: anks.sik@gmail.com research article, received 28 july 2020, accepted 30 september 2020 abstract in india, a nationwide lockdown due to covid-19 has been implemented on 25 march 2020. the lockdown restrictions on more than 1.3 billion people have brought exceptional changes in the air quality all over the country. this study aims to analyze the levels of three major pollutants: particulate matter sized 2.5 m (pm2.5) and 10 m (pm10), and nitrogen dioxide (no2) before and during the lockdown in delhi, one of the world’s most polluted cities. the data for pm2.5, pm10, and no2 concentrations are derived from 38 ground stations dispersed within the city. the spatial interpolation maps of pollutants for two times are generated using inverse distance weighting (idw) model. the results indicate decreasing levels of pm2.5, pm10, and no2 concentrations in the city by 93%, 83%, and 70% from 25 february 2020 to 21 april 2020 respectively. it is found that one month before the lockdown the levels of air pollution in delhi were critical and much higher than the guideline values set by the world health organization. the levels of air pollution became historically low after the lockdown. considering the critically degraded air quality for decades and higher morbidity and mortality rate due to unhealthy air in delhi, the improvement in air quality due to lockdown may result as a boon for the better health of the city’s population. keywords: covid-19, lockdown, air pollution, delhi, spatial interpolation introduction the world is facing unforeseen challenges to cope up with the unprecedented growth of coronavirus disease (covid-19). the exponential widespread of the covid-19 has become a global pandemic that has led to pernicious consequences in various parts of the world. covid-19 was first identified in december 2019 in the province of wuhan, china (kucharski et al., 2020; zhu et al., 2020), and around four months later it has adversely affected life and economy in more than a hundred countries (who, 2020). to curb the spread of this highly contagious disease and minimize the fatality, different countries have adopted drastic yet important measures to reduce the interaction among individuals such as banning large-scale public and private gatherings, imposing a curfew, restraining transportation, promoting social distancing, creating strict quarantine instructions, and locking down countries, states and cities, depending on the countryspecific situation. on the one hand, the cost of enacting the preventive measures against covid-19 is immense, but on the brighter side, it could have some significant benefits on society too. for example, locking down the country might do contribution to the improvement of overall environmental conditions. this improvement may partially equilibrate the cost of these counter covid-19 measures. for example, according to singh and chakraborty (2020) cities across india, which were the 14 most polluted cities during the last year in the world out of 20, are breathing some of the cleanest air after the nationwide implementation of lockdown. recently, many researchers have attempted to study the effect of covid-19 lockdown on air pollution at different levels (dutheil et al., 2020; li et al., 2020; muhammad et al., 2020; sharma et al., 2020; wang et al., 2020). since the 1990s, delhi has been ranked as one of the most polluted cities among the world’s developin g countries (gujrar et al., 2004; who, 2016). particularly, air pollution caused by onsite burning of agricultural crop residue is one of the many causes of critical levels of air pollution in the northern part of india (satyendra et al., 2013). the higher level of air pollution in the overcrowded delhi cause significant public health problems (dholakia et al., 2013; rizwan et al., 2013). due to severely degraded air quality, in 2017, a community health emergency was declared in delhi by the indian council of medical research (chowdhury et al., 2019). a study by goyal (2003) points out that vehicular emission has shown a decreasing trend due to the cng (compressed natural gas) implementation. but, the overall particulate matter concentration has seen a consistent rise (kumar and goyal, 2014; gujrar et al., 2016; nagpure et al., 2016). moreover, air pollution also has severe implications on society, economy, and the environment including climate change. therefore, it has become a 28 sikarwar and rani 2020 / journal of environmental geography 13 (3–4), 27–33. paramount concern of public health, environment, and development (kampa and castanas, 2008). however, the extent of lockdown varies across different countries and cities around the globe depending on the number of cases. undoubtedly, the lockdown has put a temporary rest to a significa nt number of social and economic activities in the countries and their people (alvarez et al., 2020; inoue and todo, 2020). overall, the significance and impacts of lockdown are yet not well understood and likely to have a significant role in the restoration of air quality (mahato et al., 2020). therefore, to analyze and to understand the temporary improvement in air quality due to covid-19 lockdown is important in delhi, which is one of the most polluted cities in the world. moreover, it could be considered as an effective alternative measure to combat air pollution issues. india first announced a public curfew on 22 march 2020, and later imposed a nationwide lockdown from 25 march 2020 till 15 april, and extended it further until 3 may 2020 to block the spread of the virus. looking at the severity of increasing numbers of infections, the third phase of lockdown was extended till 17 may 2020 with the classification of districts into three severity zones (i.e. red, orange, and green). nationwide lockdown amid the covid-19 outbreak has created a unique scope for researchers to work in this direction and to suggest future policy measures to control air pollution in cities with degraded air quality. addressing the above-mentioned points, the present study aims to understand the impact of covid-19 lockdown on the air quality of delhi by comparing the levels of air pollutants (pm2.5, pm10, and no2) before and during the lockdown. when most of the recent studies have dealt with national level measurement of air pollution based on satellite estimates (dutheil et al., 2020; li et al., 2020; muhammad et al., 2020; sharma et al., 2020; wang et al., 2020), this study attempts to analyze the data from 38 ground monitoring stations to study the lockdown effect on delhi’s air quality. study area delhi, officially the national capital territory of delhi, is a city and a union territory of india located at 28.61°n and 77.23°e (fig. 1). this city is the administrative center and the second financial capital of india. with the geographical area of 1485 km2, delhi holds the second position in the list of leading megacities of the world (united nations, 2018). it stands as india’s largest urban agglomeration with more than 15 million people with a population density of 11297 people per km2 (chandramouli and general, 2011). two prominent features of the geography of delhi are the yamuna flood-plains and the delhi ridge. this type of location provides favourable conditions for the accumulation of polluted air masses. the yamuna river was the historical boundary between the states of punjab and uttar pradesh, and its flood plains provide fertile alluvial soil suitable for agriculture but are prone to recurrent floods. delhi has been continuously inhabited since the 6th century bc (asher, 2000). through most of its history, delhi has served as a capital of various kingdoms and empires. it has been captured, ransacked, and rebuilt several times, particularly during the medieval period, and modern delhi is a cluster of many cities spread across the metropolitan region (sikarwar and chattopadhyay, 2020). fig. 1 the study was performed in the city of delhi. the map shows the administrative extent of the city and groundbased air-monitoring stations considered in the study sikarwar and rani 2020 / journal of environmental geography 13 (3–4), 27–33. 29 data and methods to assess the air quality status of delhi before and during the lockdown period, data from 38 air quality monitoring stations situated at various parts of the city has been taken into consideration (table 1). these ground monitoring stations are managed under the authority of three main organizations namely cpcb (central pollution control board), dpcc (delhi pollution control committee), and imd (indian meteorological department). the 24 -hour average concentration of three major pollutants including particulate matter 2.5 (pm2.5), particulate matter 10 (pm10), and nitrogen dioxide (no2) have been obtained from the cpcb online dashboard for air quality data dissemination (https://app.cpcbccr.com/ ccr/#/caaqm-dashboard-all/) running by the central control room for air quality management. as described by the environmental protection agency (2020) particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. particles less than 10 µm in diameter (pm10) can get deep into the lungs and some may even get into the bloodstream. particles less than 2.5 µm in diameter (pm2.5), also known as fine particles, pose the greatest risk to health. whereas no2 is one of a group of highly reactive gases and adversely affects the human respiratory system. the analysis is divided into two sections. in the first section, the trend of daily average (24 -hour) concentrations of pm2.5, pm10, and no2 are studied before and during the lockdown. considering 25 march (start of the lockdown) as a baseline, the average concentrations of air pollutants were studied from 25 february to 21 april to understand the temporal changes. the second section deals wit h the mapping of spatial changes in the levels of air pollution before and during the lockdown. the spatially interpolated maps of concentrations of air pollutants on 25 february and 21 april have been generated to estimate the spatial changes in air quality in the city. interpolation methods, in general, share the same basic mathematical foundation. they all estimate the value at an unmeasured location as a weighted average of the measurements at surrounding monitoring stations. they differ in their choice of sample weights and the surrounding stations (xie et al., 2017). this study has used the inverse distance weighting (idw) method of spatial interpolation of air pollutants. in air pollution modelling the idw method is popular and widely used among scholars (hoek et al., 2002; salam et al., 2005; neupane et al., 2010; chen et al., 2014). it is applied operationally by the environmental protection agency (epa) for generating real-time o3, pm10, and air quality index spatial predictions in nationwide scales (deligiorgi and philippopoulos, 2011). the value z 0 at the unknown point is calculated as: 𝑍0 = ∑ 𝑍𝑖 𝑑𝑖 −𝑛𝑁 𝑖=1 ∑ 𝑑𝑖 −𝑛𝑁 𝑖=1 where z0 is the estimation value of variable z at point i, zi is the sample value in point i, di is the distance of the sample point to the estimated point, n is the coefficient that determines weight based on a distance, and n is the total number of predictions for each validation case. the basic principle of the interpolation methods is based on the assumption that points closer to each other are highly correlated and more similar than those farther. this method will be used by a region in which there are enough sample points (at least 14 points) that are spatially dispersed all over the region (burrough and mcdonnell, 1998). results and discussion temporal trends of air pollution before and during the lockdown there has been a significant change in the levels of pm2.5 before and during the days of covid -19 lockdown in delhi (table 1 and fig. 2). all the stations in the city have recorded considerable lowering of pm2.5 concentrations during the studied period. the average pm2.5 concentrations in the city has reduced from 122.48 µg/m3 on 25 february 2020 to 17.71 µg/m3 on 21 april 2020. moreover, at the beginning, all stations within the city have reordered pm2.5 concentrations much higher than the standard (25 µg/m3) set by the who. a noteworthy point here is that, on the last day of studied time, 29 stations out of the 35 have recorded pm2.5 concentrations below the who standard. the levels of pm10 concentration have strikingly reduced all over delhi after the imposition of covid 19 lockdown in the city (fig. 2). table 2 shows the declining levels of pm10 concentration before lockdown (25 february) and during lockdown (21 april). it should be noted that the average pm10 concentration in the city has remarkably reduced to 47.46 µg/m3 on 21 april (during lockdown) from the critically higher level of 216.49 µg/ m3 on 25 february (before lockdown). furthermore, the concentration of pm10 was recorded extremely higher than the who standards (50 µg/m3) in all stations. these critical levels of pm10 in the city have reduced after the lockdown and 17 out of 31 stations ha ve recorded the concentration below who standards. https://app.cpcbccr.com/ 30 sikarwar and rani 2020 / journal of environmental geography 13 (3–4), 27–33. table 1 details of the ground monitoring stations selected for the study and levels of pm2.5, pm10 and no2 concentration before and during covid-19 lockdown id station name, authority lat lon before covid-19 lockdown (25 february 2020) during covid-19 lockdown (21 april 2020) pm2.5 pm10 no2 pm2.5 pm10 no2 1 alipur, delhi dpcc 28.7972 77.1331 110.12 206.45 52.61 52.61 52.61 13.4 2 anand vihar, delhi dpcc 28.6502 77.3027 88.52 209.39 57.14 20.88 81.18 33.55 3 ashok vihar, delhi dpcc 28.6909 77.1765 136.33 218.4 62.79 8 36.5 6.2 4 aya nagar, delhi imd 28.4720 77.1329 72.75 154.72 24.52 36.88 34.54 12.2 5 bawana, delhi dpcc 28.7932 77.0483 140.54 236.46 36.48 13.64 61.27 12.95 6 burari crossing, delhi imd 28.7551 77.1607 na na na na na na 7 dr. k s shooting range, delhi dpcc 28.4997 77.2670 124.28 206.47 75.09 4.6 24.75 1.32 8 dtu, delhi cpcb 28.7499 77.1183 167.98 300.16 33.55 6.95 46.41 16.44 9 dwarka-sector 8, delhi dpcc 28.5720 28.5720 151.08 293.88 55.41 8.68 39.23 9.59 10 east arjun nagar, delhi cpcb 28.6561 77.2947 na na 65.67 na na 20.85 11 igi airport (t3), delhi imd 28.5550 77.0844 92.32 191.91 27.62 7.68 28.81 na 12 ihbas, dilshad garden, delhi cpcb 28.6811 77.3047 103.69 na 52.32 11.35 na 10.06 13 ito, delhi cpcb 28.6275 77.2437 177.24 238.21 28.17 133.46 128.89 18.67 14 jahangirpuri, delhi dpcc 28.7296 77.1666 132 275.5 99.03 10.95 39.41 62.99 15 jawaharlal nehru stadium, delhi dpcc 28.5828 77.2343 90.64 176.33 41.04 3 27.77 8.8 16 lodhi road, delhi imd 28.5910 77.2280 84.02 175.81 31.17 59.93 73.8 22.58 17 mdcns, delhi dpcc 28.6125 77.2373 117.83 204.93 59.93 7.35 22.85 8.84 18 mandir marg, delhi dpcc 28.6341 77.2004 90.78 204.65 54.45 14.05 38.3 26.14 19 mathura road, delhi imd 28.6112 77.2401 100.97 234.49 45.94 6.94 39.63 15.52 20 mundka, delhi dpcc 28.6823 77.0349 207.6 315.64 25.94 9 62 26 21 najafgarh, delhi dpcc 28.6090 76.9854 119.46 164.06 27.54 46.24 154.73 na 22 narela, delhi dpcc 28.8548 77.0892 136.15 245.52 44.75 6.3 52.4 30.49 23 nehru nagar, delhi dpcc 28.5638 77.2608 147.88 241.8 34.14 7.72 29.5 11.88 24 north campus, du, delhi imd 28.6889 77.2141 84.09 172 31.67 24.4 na 12.88 25 nsit dwarka, delhi cpcb 28.6102 77.0378 134.63 na 30.89 28.05 na 11 26 okhla phase-2, delhi dpcc 28.5492 77.2678 133.5 238.27 48.61 8.5 33.1 10.58 27 patparganj, delhi dpcc 28.6347 77.3045 106.91 144.35 29.41 4.18 27.09 8.72 28 punjabi bagh, delhi dpcc 28.6619 77.1241 146.86 212.91 41.87 7.67 37.36 13.67 29 pusa, delhi dpcc 28.6376 77.1571 131.78 215.6 71.16 1.08 22.45 18 30 pusa, delhi imd 28.6340 77.1678 73.27 152.18 14.15 na na na 31 r k puram, delhi dpcc 28.5503 77.1851 98.73 219.36 54.32 5.75 21.2 7.55 32 rohini, delhi dpcc 28.7382 77.0822 164.95 233.29 26.12 11.91 56.09 8.06 33 shadipur, delhi cpcb 28.6510 77.1562 107.44 na 86.72 13.21 na 11.15 34 sirifort, delhi cpcb 28.5505 77.2147 144.53 254.05 47.74 7.8 38.85 9.08 35 sonia vihar, delhi dpcc 28.7332 77.2495 104.68 183.97 47.29 6.2 35.3 17.27 36 sri aurobindo marg, delhi dpcc 28.5563 77.2063 113.35 174.23 32.3 5 19 2.66 37 vivek vihar, delhi dpcc 28.6712 77.3176 124.02 199.71 43.5 9.5 64 16.41 38 wazirpur, delhi dpcc 28.6975 77.1604 148.51 249.38 75.81 10.3 42.2 22.29 average 122.48 216.49 46.40 17.71 47.46 15.82 dpcc: delhi pollution contro committee, imd: indian meteorological department, cpcb: central pollution control board n.a.= data not available for particular day source: central control room for air quality management, delhi ncr sikarwar and rani 2020 / journal of environmental geography 13 (3–4), 27–33. 31 table 1 illustrates the no2 concentrations in delhi at various stations for two time periods i.e. before covid-19 lockdown (25 february 2020) and during covid-19 lockdown (21 april 2020). all the stations have recorded a pronounced reduction in no 2 concentrations during the considered period. though the majority of the stations have recorded no 2 concentrations below the who standard (80 µg/m3), the average 24-hour levels have further dropped from 46.40 µg/m3 on 25 february to 15.82 µg/m3 on 21 april. the trend of day to day no 2 concentration level decrease before and during the lockdown in all the stations of delhi has been presented by the line diagram (fig. 2). there has been a remarkable lowering of no 2 levels after 24 march when the covid-19 lockdown started in india. it is also noticeable that the levels of no2 are considerably under control in the city compared to the critical levels of particulate matter. it is indicative that the levels of air pollution declined gradually over the studied period with a steep fall from 25 march and reached historical low levels. moreover, there is a notable difference between declining patterns of pm and no2 (fig. 2). this difference can be justified with various reasons. the lockdown due to covid-19 has strictly restricted all construction activities and movement of vehicles, which were responsible for previously higher levels of pm in delhi (kathuria, 2004; taneja et al., 2016). thus there is a sharp change in pm levels before and during the lockdown. however, as noted by sikarwar and chattopadhyay (2020) the levels of no2 concentrations in the city were already recorded below the standards and thus, showed a gradual decline during the lockdown. spatial changes in the level of air pollution before and during the lockdown before lockdown (25 february) the stations have recorded high levels of pm2.5 and the most polluted areas of the city have pm2.5 concentrations above 106 µg/m3 (fig. 3). furthermore, our analysis found that the concentration was significantly high in the western part of the city but these concentration levels have trickled down remarkably during the lockdown (25 february) fig. 2 trend of pm2.5, pm10, and no2 concentrations [µg/m3] before and during the lockdown in delhi fig. 3. spatial concentrations of pm2.5 in delhi before (25 february 2020) (top) and during (21 april 2020) (bottom) covid-19 lockdown. when pm2.5 concentrations were below 30 µg/m 3 in the maximum areas of the city. the concentration of pm10 in the city before and during lockdown is presented with spatially interpolated surface maps too (fig. 4). before lockdown (25 february), the concentration of pm10 was critically high, when pm10 concentration was observed above 140 µg/m3 in the most polluted areas of delhi. the north-western and south-eastern parts exhibit the presence of an extreme level of pm10 in the air. however, these concentration levels have reduced significantly to lower levels during the lockdown (25 february) as the maximum area of the city has pm10 concentration below 56 µg/m3. the interpolated maps of no2 concentrations before and during the lockdown in delhi clearly show that the no2 concentration in delhi has reduced to notable levels after the implementation of lockdown in the city (fig. 5). the analysis shows, that before the lockdown, mainly the eastern part of the city had higher concentrations of no2, which further declined during the lockdown. it was also found that the southern part of the city has experienced better air quality in terms of no2, during the lockdown. however, the levels of no 2 concentration remained higher in the northern parts of the city. 32 sikarwar and rani 2020 / journal of environmental geography 13 (3–4), 27–33. fig. 4. spatial concentrations of pm10 in delhi before (25 february 2020) (top) and during (21 april 2020) (bottom) covid-19 lockdown conclusions since many indian metro cities have been in the list of the world’s most polluted cities, a sudden significant improvement in the air quality of delhi has international relevance for environmental policies. lockdown due to covid-19 in various parts of the world has provided an opportunity to measure human impact on the natural environment particularly in big cities. when urban mega hubs have been running continuously for economic development without considering the limits of natural resources, measures like temporary lockdown may emerge as an effective solution to control environmental imbalance. with the use of the idw method of spatial interpolation, the study estimated concentrations of pm2.5, pm10, and no2 before and during covid-19 lockdown in delhi. it is found that the lockdown in the city has positively impacted the air quality. the results reveal that just after one month of the lockdown the reductions in pm2.5, pm10, and no2 concentrations were by 93%, 83%, and 70% respectively. consequently, the levels of air pollution are historically low during the lockdown when compared to the levels estimated in previous studies on delhi (kumar and foster, 2009; dholakia et al., 2013; rizwan et al., 2013). considering the critically degraded air quality for decades and fig. 5. spatial concentrations of no2 in delhi before (25 february 2020) (top) and during (21 april 2020) (bottom) covid-19 lockdown higher morbidity and mortality rates due to unhealthy air, the improvement in air quality due to lockdown may result as a boon for the better health of the city’s population. this temporary improvement in the air of the capital city gives a positive indication of another chance to mitigate the damage we have done to the environment. therefore, the study should be considered as a useful supplement to the regulatory authorities that may lead to reconsider the current plan and policies to combat degraded air quality in the 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https://trove.nla.gov.au/work/23430924 https://www.epa.gov/pm-pollution/particulate-matter-pm-basics https://www.epa.gov/pm-pollution/particulate-matter-pm-basics https://www.bloombergquint.com/ https://www.who.int/airpollution%20/data/cities-2016/en/ https://www.who.int/airpollution%20/data/cities-2016/en/ introduction study area data and methods results and discussion temporal trends of air pollution before and during the lockdown spatial changes in the level of air pollution before and during the lockdown conclusions acknowledgments references journal of env. geogr. vol. iii. no. 1-4. pp. 1-9. catchment-scale relief development as the result of long-term agricultural activity, case study on szekszárd hills, hungary benyhe, b. – kiss, t. university of szeged, department of physical geography and geoinformatics, 6722 egyetem u. 2, szeged, hungary abstract human impact has played important role in the relief development of szekszárd hills, as the history of viniculture dates back to the roman times. approximately 17 % of the area is used as vineyard. as viniculture is one of the most intensive land-use type and soil erosion is very severe on the loose loessy material of these hills, relief development is quite fast in the area. the aim of the study to estimate the catchmentscale erosional loss of the area caused by viniculture and to evaluate the role of artificial terraces on landscape development. three smaller catchments were chosen as study areas in the north-east part of the hills. based on the digital elevation model of the area the minimum net erosion was calculated. the calculations reflect that the amount of erosion was higher (1) on the slopes with southern exposure and (2) in tributary valleys close to the town. the accelerated erosion altered the longitudinal profile of the tributaries and the terraces changed the profile of the intercollin ridges. keywords: relief development, catchment-scale erosion, viniculture, artificial terraces introduction since the early periods of agriculture the surface has been changed by human impact. ploughing is the oldest surface-modifying agricultural activity, but its effect was different in different periods and regions. the invention of agricultural tools (e.g. plough) allowed the cultivation of areas have not been used previously. the main effect of ploughing is evening the surface, but it also accelerates erosion resulting the reshaping of the landscape (szabó 2006). agriculture has direct and indirect impacts on landforms and in landscape development. the direct forms have been made on purpose, like ditches and channels to drain run-off or terraces to make steep slopes cultivable. indirect forms developing by natural processes but driven by human impact, like ridges and furrows as the result of ploughing, gullies due to soil erosion, bank-in roads and artificial terraces in hilly areas. cultivation of terraces has a few thousand years-old history. it is most common in east-asia where rice is cultivated on the terraces, but they can also be found in the wine and fruit producing regions of europe. various types of terraces exist depending on climate, landscape and tradition. the surface of the terraces can be horizontal or gently sloping, they can be supported by walls and may have rim at the edges (szabó 2006). regardless of their form, the creation of the terraces requires great amount of artificial material transport and deposition. the construction of terraces has numerous unfavourable environmental effects, especially in areas where their planning is not precise. in these areas runoff usually increases due to the disturbance of the surface and changed vegetation, and this results accelerated erosion (white et al. 1984). therefore, drainage ditches are often built on the terraces to control run-off, however these ditches alter the timing of stormflow, increasing the discharge of the main stream and causing larger floods. besides the above described human induced changes the relief development still show the classical development phases typical for all landscapes. the studies on surface evolution of hilly or mountainous regions began in the 19 th century. the concept of denudation cycle was developed by davis and challenged by penck and others (summerfield 1991). in the davisian theory surface dissection of a raised area is controlled by streams which besides incision eroding the intercollin ridges, decreasing the angle of the slopes (slope decline) and the elevation of the area. this theory is applicable to many hilly areas of the mid-latitudes, but it is quite general and considers fluvial erosion as the only one process in landscape development. penck also worked out a model of slope development, but in his slope replacement model the process of flattening (erosion of the intercollin ridges) is from the base upwards when the slope profile is getting lower as the slope retreats. based on the degree of erosion followed by the disturbance (uplift) stages of relief development were defined (i.e. youth, mature and old age). though these models are quite simple and neglect several factors, some of their elements (i.e. slope development) still can be considered in modern relief modelling studies. on agricultural areas and terraces accelerated soil erosion is the main process in altering the relief, but is role in long-term landscape development is rarely evaluated. mostly, because soil erosion is usually studied on small parcels (e.g. davis 1976, stolte 2003, kitka et al. 2009), but rarely on larger areas. the aim of the research is to estimate the amount of (soil) erosion on catchment-scale relief development and to evaluate the geomorphic changes from the point of view of duration of human impact. the szekszárd hills were chosen as a study area, because they are one of the vine producing areas of hungary with the oldest traditions. here viniculture, which is one of the most inten2 benyhe b. – kiss t. joeg iii/1-4 sive land-use, is combined by the formation of terraces. the problem is, that the region is characterised by thick loessy deposits, therefore the hilly surface is highly erodible. on about half of the region the rate of soil erosion is over 90 % (ádám 1964), but considering the study area the spatial extension of such highly eroded soils is even more, as it is over 90 %. study area the study area is located in the north-eastern part of szekszárd hills, which is the easternmost member of the transdanubian hills (fig. 1). the study area represents three catchments of the region, west of the town of szekszárd, which is the regional center. the size of the studied catchments is increasing towards south and their total area is 11.7 km 2 . the highest point of the study area is located on the south-east divide of the area (285.9 m asl), the mean height is 145 m asl the relative relief of the area is 120-150 m/km 2 . the studied catchments are opened towards east, the tributaries are perpendicular to the main streams (fig. 2). the main features of the landscape were formed during the pleistocene, when thick 40-50 m loess and loessy materials were deposited (marosi 1990). in the middle pleistocene the area was elevated between faultlines. a steep scarp developed on the eastern edge of the studied catchments separating them from the sinking plain (ádám 1969). valley incision started due to the pronounced relief differences along the tectonic fault. in the catchments the slopes are asymmetric as slopes with southern exposure are longer. this asymmetry partially can be explained by tectonism, but also by pleistocene solifluction and holocene fluvial erosion (ádám 1964). the bottom of the valleys are wide (fig. 2), due to the intensive accumulation of the eroded sediment and probable due to human impact (pécsi 1981). the average mean temperature of the study area is 10.2-10.5 °c. the annual mean precipitation is 650 mm, and because of the continental climatic trends most of it (380-400 mm) falls at summer. this is important in relief development, as heavy summer rainfalls have greater effect on surface erosion (kerényi 1991, pinczés 1980). the original vegetation was oak, ash and elm forests (querco-ulmetum, convallario-quercetum), but it fig. 1 location of the study area joeg iii/1-4 catchment-scale relief development as the result of long-term agricultural activity, case study … 3 was cleared since the middle ages, therefore nowadays only 28 % of the area is forested. fragments of natural vegetation can be found in the bottom of the narrow valleys and ravines. the forests were replaced by agricultural fields, especially vineyards. most of the area is covered by brown forest and forest-steppe soils, though they are strongly eroded especially under vineyards (pécsi 1981). history of viniculture of the study area the production of vine in the western part of hungary dates back to the roman ages (balassa 1982).viniculture was already introduced in the szekszárd hills during the reign of emperor probus (4 th c. ad), when not only legionnaires (syrians) and the settled veterans cultivated vineyards here, but also the local paleochristians and celts (töttős 2008). the exact history of the viniculture in the middle ages is not known. in the 12-13 th centuries vallons and serbians fleeing from the ottomans and germans from the west europe also played important role in enriching the traditions of the hungarian vine production. by the 13 th century about 3-5 % of the area of the country was covered by vineyards, and this ratio (or may be even greater) probably was also characteristic in szekszárd (kaczián 2004). during the ottoman-hungarian wars (16-17 th c.) the vineyard area of szekszárd – unlike the others in hungary – remained almost unharmed, its prized vines were drank by the osmans too, despite of the prohibition of the coran. the vine became a precious product of the town being its main income. in 1728 the total area of vineyards was 78 ha and by 1769 it increased to 350 ha. the vine became a premise of prosperity to the town, as before the river regulation works the floods of the danube and sárvíz rivers often ruined the plough fields on the plain. in these years the trade of vine made possible to buy the needed cereals (kaczián 2004). in the end of the 19 th c. the vineyards of hungary were seriously damaged by the contagion of grape phylloxera. the damage was especially great on vineyards, where the soil was not loose, so on loess and rhyolite tuff, though the pest caused less damage on sandy soils. therefore, after the phylloxera pest the vine producing regions were rearranged: originally only ca. 14 % of vineyards were located on sandy areas, but after 1890 it increased to 59 % and many of the traditional vine producing areas were abandoned (balassa 1982). in the vineyards of szekszárd the harm was made in vine quality but not in quantity. here, by 1910 as a result of the replantation campaign the total area of the vineyards increased by 25 %. in the 1960’s new grape species and machinery were introduced to serve the demands of mass vine production. the steeper areas were not cultivable by machines, therefore the vineyards were relocated at the foothills and larger terraces were formed. as the territory fig. 2 3d-view of the sub-catchments 4 benyhe b. – kiss t. joeg iii/1-4 of foothills is limited, the new plantations occupied the less sunny northern and western slopes. besides deep bank-in roads were covered by concrete making the transportation easier. this promotes suburbanization, which also has an unfavourable effect: houses and other infrastructural objects were built on vineyards, therefore the traditional landscape altered decreasing the esthetical and traditional value of the vineyard region (máté 2001). effects of viniculture on relief development vineyards were traditionally hoed twice a year, but from the 19 th c. grape rows were hoed three times a year to improve the quality of the vine. at the same time ridges were formed between the rows and the trenches under them to collect the summer precipitation for the plants (balassa 1982). as the grape rows run perpendicularly to the contour-lines, these small artificial trenches had increased the run-off considerably, accelerating linear soil erosion (kerényi 1991). the trenches were buried after the harvest to protect the roots from frost, therefore their effect on enchanting erosion was pronounced right in the stormy summer season. in the vineyards soil erosion was so intensive, that for example in 1961 the streets of szekszárd were buried under 25,000 m 3 mud eroded from the vineyard hills during a heavy summer storm (pataki 1961). in the course of intensive cultivation the dirt roads were used frequently. under the vehicles the loess lost its original structure and the weathered material was eroded down slope. in this way bank-in roads were developed along the transportation routes. these bank-in roads are usually 5-6 m deep, but some incised up to 1012 m depth depending on the frequency of use. in some cases they transformed into 20-25 m deep ravines, thus they do not function as roads any more (ádám 1964). the bank-in roads are about 1-4 m wide depending on the size and type of the transport vehicles, and they are broadening due to lateral erosion. on the steep slopes terraces were created to support viniculture (marosi 1990). the territory, elevation and the morphology of the walls of the terraces is quite diverse: near to the town the terraces are smaller and higher as they occupy quite steep slopes, whilst the further vineries are on lower terraces with larger area and less steep slopes. the walls of these terraces ranges between 1 and 4 m, they are usually very steep. the larger terraces are cultivated using heavy machines, here the soil is compressed decreasing its infiltration capacity, therefore runoff and erosion is more intensive on the lower areas than on higher and smaller terraces (pataki 1961). methods since the aim of the study is to evaluate effect of agriculture on relief development on a larger area (11.7 km 2 ) gis tools were applied. in order to determinate the amount of eroded material the volume of the present day and the potential relief was calculated. the volume of the present day surface was calculated for each subcatchments, and it was defined as the volume between the present day surface and the base level surface was drawn at the height of the outlet of the sub-stream. the volume of the potential relief was defined as the volume between the imaginary flat surface between the points of the opposite divides and the base level. the amount of net erosion was calculated by substructing the volume of the present day relief from the volume of the potential relief. some slopes of the main streams drain the run-off directly into the main stream, and these areas were not considered during the study (i.e. valley slope between bc sub-catchments of no.2. catchment (fig. 1). to perform the measurements the digital elevation model (dem) of the area was created. the basis of this dem was 1:10000 scale topographic contour maps in eov projection system (eov – national standardized projection system of hungary). the dem was created as a raster feature under arcgis 9.3, applying the topo to raster option with a resolution of 2 m. the subcatchments were generated as polygons, separated from each other along their divides. in order to measure erosion a new tin elevation models were created for each sub-catchment, where the potential surface was created by segments connecting the top of the divides (fig. 3). then from these tins a raster dem representing the potential surface was created for each sub-catchments. using the potential and the present day surfaces the software can calculate the volume differences (net erosion) using cut/fill option. the longitudinal profiles of the valley floors and divides were performed by interpolate line function. the profiles were compared based on their concavity index defined by langbein. concavity was calculated as it follows (knighton 1998): h a c 2  where c is concavity, a is the elevation difference between the mid-point of the profile and the middle of the line aligned to the end points of the profile, and h is the total height difference of the profile. joeg iii/1-4 catchment-scale relief development as the result of long-term agricultural activity, case study … 5 results and discussion 1. longitudinal profiles of the valleys and divides the main valleys run from west to east, therefore the longitudinal profiles of their tributaries show typical trends based on the exposure. the tributaries with southern exposure have concave profiles. the concavity indices of these valleys fall between 0.0 and 0.34. the greatest values were measured in the easternmost tributaries near to the outlet of the main valley. the concavity index of the tributaries exposed to south decreased towards west, as the westernmost valley has a value of 0.0 suggesting that the valley floor is almost straight. in contrary, the tributaries exposed to north has smaller concavity index, as it varies between -0.35 and 0.25, negative values mean that the longitudinal profile of a valley is convex (fig. 4). the differences between the valleys suggest that fluvial erosion dominates in the valleys exposed to south, while in valleys exposed to north the convex longitudinal profiles indicate the dominance of derasional processes (as freeze and thaw activity). there is also difference in the longitudinal profiles of the divides. the divides with northern exposure have smooth curves, whilst the southern exposure divides are less steep, but they characterised by several breaks in their longitudinal profiles. these brakes and steps show the location and extension of the artificial terraces carved into the loess ridges. some divides are gently terraced (see bc profile on fig. 4b), while others has huge terraces, especially near the outlet of the main stream (see ab or cd profiles on fig. 4b). these altered longitudinal profiles suggest huge artificial material transport on slopes with southern exposure. 2. amount of net erosion the construction of potential surface enabled to calculate the amount of net erosion (%) of each sub-catchment. the catchments exposed to south are much more eroded (min: 7.5 and max: 30.3 %), than the sub-catchments on the opposite side (min: 1.0 and max: 22.1 %). however, the mean values of southern exposure sub-catchments are larger (18.6-25.8 %) in all the three catchments. the most fig. 3 present-day and potential relief of a sub-catchment fig. 4 longitudinal profiles of the valley floors (a) and the intercollin ridges (b) in case of no.1. catchment (black lines: southern exposure; grey lines: northern exposure) 6 benyhe b. – kiss t. joeg iii/1-4 incised valleys and the most eroded surfaces (net erosion: 23.4-30.3 %) are located in the north-west part of the southern catchment. these tributaries have the largest area, suggesting that there is a positive connection between the net erosion and the size of the sub-catchment. however, but there are several smaller sub-catchments with similar amount of erosion (e.g. 1/c: 17.5 %; 2/a: 24.4 %) indicating that there is no close connection between the size of the valley and the amount of erosion. however, there is an increasing trend of the amount of erosion from east to west (from the valley-mouth to the upper part of the main catchment) on both sides of the main valleys, suggesting more intensive erosion of the interior sub-catchments. however, it opposes the general surface-development model, where headward erosion proceeds from the mouth of a catchment to its highest parts, therefore, the net erosion of the upper parts (interior) of the catchments is lower. however, this statement is valid just in the first stages of the surface dissection (juvenile state), when the ridges have not been eroded yet. by the progress of the surface development (mature state) the ridges and divides will also erode and they become lower by some kind of slope development (i.e. davisian slope-decline or penk’s slope-replacement). therefore the divides of sub-catchments closer to the mouth of the main watershed are eroded longer, therefore in greater degree than the ones in the upper part of the catchment. the studied catchments are in this phase of the development, as the divides on the eastern (outlet) part of the catchment are lower by 30-40 m than the inner ones (fig. 4b). therefore, it must be considered as natural feature that the valleys in the interior of the watersheds seems to be more eroded, because the ridges at the edge of the hills had already suffered erosion. hence, the calculated net erosion is strongly underestimated, especially in tributary catchments near the mouth of the main stream. as it was mentioned above, the amount of net erosion is increasing towards west. however, some subcatchments do not fit into this trend (fig. 5), as over-par erosion (14.8-24.4 %) was measured in some cases on slopes with southern exposure near the catchments mouth, near the town (e.g. 1/a-b-c or 2/a). therefore, here the surplus-erosion can be explained by concentrated anthropogenic impact, as longer history of cultivation, thus longer accelerated soil erosion (table 1). fig. 5 calculated net-erosion of the sub-catchments. (the main catchments are numbered 1-3, the sub-catchments are labelled a-q counter-clockwise) joeg iii/1-4 catchment-scale relief development as the result of long-term agricultural activity, case study … 7 the evidence on intensive erosion close to szekszárd has been confirmed by field work. some of the bank-in roads run on divides, cut 2-3 m deep into the surface serve as good examples on rapid erosion and fast divide erosion. in some cases the back-wall of terraces carved into the slope almost reaches the walls of the bank-in roads, and there is only about a 0.5-1 m thick loess edge left (fig 6). in other cases these narrow loess table 1 main and erosional parameters of the studied sub-catchments exposure subcatchment area (m 2 ) valley mouth ( m asl.) volume of potential relief (m 3 ) erosional loss (m 3 ) net erosion (%) mean erosion (%) northern catchment (1) so u th 1a 215228 117.1 13 970 734 2 060 809 14.8 18.6 1b 223728 126.4 13 274 964 2 052 116 15.5 1c 253120 129.8 18 714 351 4 572 060 24.4 1d 115612 129.8 7 056 410 912 091 12.9 1e 182108 138.5 12 397 993 1 914 608 15.4 1h 164828 155.1 12 332 149 2 766 586 22.4 1i 277852 156.4 20 601 181 4 026 051 19.5 n o rt h 1j 208492 170 13 108 539 1 862 993 14.2 12.9 1k 93056 170.3 4 589 618 613 494 13.4 1l 36076 166.8 1 414 534 77 750 5.5 1m 34216 165.8 1 345 001 61 617 4.6 1n 108380 139.3 6 804 375 918 877 13.5 1o 80504 136.6 4 178 669 535 915 12.8 central catchment (2) so u th 2a 295580 126 18 697 600 3 264 944 17.5 15.7 2b 106864 128.9 5 416 098 406 894 7.5 2c 188308 139.4 13 184 667 1 587 495 12 2d 128520 159 7 648 957 1 129 323 14.8 2e 210060 166 15 264 293 3 452 949 22.6 2f 113720 166 7 520 924 1 154 506 15.4 2g 108328 166 8 085 736 871 967 10.8 n o rt h 2h 153364 178.6 9 718 391 1 000 912 10.3 7.5 2i 91592 178.6 5 519 206 530 701 9.6 2j 127168 165.4 7 731 536 772 465 10 2k 109380 153.5 5 080 230 467 311 9.2 2l 64524 154 2 355 509 24 510 1 2m 92456 135.5 4 709 677 253 505 5.4 2n 171736 134.9 10 653 162 320 281 3 2o 80416 137.1 5 776 133 268 102 4.6 2p 120408 136.3 7 901 118 178 596 2.3 2q 280184 127.5 14 857 053 1 785 909 12 southern catchment (3) so u th 3a 51020 110.2 1 583 665 128 675 8.1 25.8 3b 326412 115 22 152 245 4 172 991 18.8 3c 219560 118.5 13 351 380 1 573 724 11.8 3d 938212 116.1 84 635 592 22 580 641 26.7 3e 1275716 120.3 119 495 600 36 185 369 30.3 3f 1253228 128.8 129 301 639 33 722 601 26.1 3g 1172324 128.8 109 324 174 25 615 504 23.4 n o rt h 3h 778828 127.5 71 325 942 15 766 935 22.1 17.6 3i 289448 127.5 18 994 362 1 732 918 9.1 3j 365384 127.5 28 313 881 5 550 291 19.6 3k 285168 114.2 20 389 781 2 218 838 10.9 3l 256724 113 17 548 181 2 310 230 13.2 8 benyhe b. – kiss t. joeg iii/1-4 walls have already been cut off, and the originally deep bank-in roads are relatively raised over the terraces, bordered with 1-2 m high strip wall. these examples show that surface erosion due to recent anthropogenic terrace formation is so high that the ridges erode and lower quite rapidly. it also support the idea, that the net erosion measured by gis method is lower than the real erosion, as the recent divides under human impact are at least few meters lower than the possible natural surface, so the real volume of erosion can be much higher than the measured. conclusion in the study area viniculture has a long history. on slopes exposed to south and close to the town it probably had begun earlier, therefore runoff accelerated and linear erosion became dominant. therefore, here the valleys have concave longitudinal profile, and the divides between the sub-catchments are also more eroded and large terraces dissect them. valleys with northern exposure probably were cultivated less intensively and the vineyards are probably younger, therefore valley development was significantly slower and the slopes suffered less erosion. the gis analyses showed that catchment with southern exposure are eroded most intensively (net erosion 15-25 %), as they lost 8 % more material than of the catchment with northern exposure (net erosion 7-17 %). sub-catchments closer to the town of szekszárd have greater amount of erosion, as it is shown by the high erosional values not fitting into the trend of natural surface dissection. besides, near to szekszárd the divides have already been eroded, therefore the results of the calculations are under estimated. since there is no possibility to reconstruct the real original relief no more precise data can be obtained on the volume of net erosion. to solve the problem we plan to calculate the volume of deposited material in the form of alluvial fans and to date the deposit by absolute dating methods (osl) to determine the age of the deposited material and the rate and periods of erosions. references ádám l. 1964. a szekszárdi-dombvidék kialakulása és morfológiája. földrajzi tanulmányok 2: 69 ádám l. 1969. a tolnai-dombság kialakulása és felszínalaktana. földrajzi tanulmányok 10: 186 balassa i. 1982. magyar néprajz. budapest: corvina kiadó, 214-216 davis m. b. 1976. erosion rates and land-use history in southern michigan. environmental conversation 3/2: 139-148 kaczián j. 2004. szekszárd – a nemes borok és a művészetek városa. szekszárd: palatinus-séd nyomda, 19-23 kerényi a. 1991. talajerózió. budapest: akadémiai kiadó, 1534 knighton d. 1998. fluvial forms and processes. london: arnold publ., 242-245 marosi s. 1990. magyarország kistájainak katasztere ii. budapest: mta fki, 564-568 máté a. 2001. a szekszárdi borvidék rendszerváltozás utáni gazdasági helyzete. magyar földrajzi konferencia, szeged, cd-publication pataki j. 1961. az antropogén morfológia és a gyakorlati élet. földrajzi közlemények 4: 301-306 pécsi m. 1981. a dunántúli-dombság. budapest: akadémiai kiadó, 121-124 pinczés z. 1980. a művelési ágak és módok hatása a talajerózióra. közlemények a debreceni klte földrajzi intézetéből, budapest: akadémiai nyomda 357-379 fig. 6 a bank-in road running on a divide. a: the bank-in road became elevated, as the terraces eroded intensively on both sides, thus now the road is bordered by terrace back-walls. b: the same road continues between 2-3 m high loess walls, however they are only 0.3-0.5 m wide walls, behind cultivated terraces are. joeg iii/1-4 catchment-scale relief development as the result of long-term agricultural activity, case study … 9 stolte j. 2003. modelling water flow and sediment processes in a small gully system on the loess plateau in china. catena 54: 117-130 summerfield m. 1991. global geomorphology. singapore: longman publishers, 184-185 szabó j. 2006. antropogén geomorfológia. debrecen: kossuth egyetemi kiadó, 64-70 töttős g. 2008. szekszárd: mesélő útikönyv. szekszárd–paks: demeter dél-mezőföld természetbarát egyesület, 133-152 white i. d. – mottershead, d. n. – harrison s. j. 1984. environmental systems. london: allan&unwin, 436-469 journal of environmental geography journal of environmental geography 6 (1–2), 49–55. doi: 10.2478/v10326-012-0006-0 issn: 2060-467x estimation of tourism climate in the lake balaton region, hungary ákos németh climatology division, hungarian meteorological service, kitaibel p. u. 1., h-1024 budapest, hungary e-mail: nemeth.a@met.hu research article, received 24 january 2013, published online 15 april 2013 abstract lake balaton is one of the most important and best-known tourist destinations in hungary. although in the last few years, several efforts were implemented to increase the length of the tourist season, the highest visitor turnover occurs in the summer months. we mostly regard the lake balaton as a bathing place, despite of the fact that the region offers more and more tourism products. the beach tourism and other lakeside activities are highly dependent on weather and climate. in order to know that a region's climate what extent is suitable to the given tourism activities, the tourism climate potential must be determined. this study aims to illustrate observed changes of the tourism climate potential of lake balaton region during the last half century, by using tourism climatic index (tci) and climate-tourism-information-scheme (ctis). the analysis is based on the long-term measured datasets of siófok synoptic station. based on the tci, the tourism climate potential of the examined region is barely changed over the past 50 years; significant changes can be detected only in february and june. by using the ctis, smaller changes can also be detected. such changes are: moderate improvement of the thermal comfort in spring and autumn, slight increase in sunny hours in the tourism season, as well as the sultriness becomes more frequent in the summer months. the results may represent useful background information to the policy decision-makers. keywords: tourism climatic index, climate-tourism-information-scheme, tourism climatology, climate change, lake balaton introduction despite of the economic crisis, tourism is one of the major economic sectors in hungary. in 2011 tourism produced 1115.7 billion hungarian forints (about 5.1 billion usd) revenue, which means second-third place in industry-wide comparison. the contribution to the gross domestic product (gdp) is approximately 6%. in addition, more than 8% of the all employees are working in tourism sector. the lake balaton r egion plays an important role in hungarian tourism. the lake balaton or as the hungarians call it, the “hungarian sea”, is the largest fresh water lake in central europe with significant lakeside tourism. the southern shore of balaton is ideal for small children because of the shallow water, but on the north shore the water gets deep faster. in summer the water te mperature is around 26 °c, which is warmer than the average air temperature in the morning and in the evening. it can be said that the water and the cli mate are the main attractions of this region. according to kéri (1974), meteorological point of view this means that if the weather does not hamper the tourists for enjoying the water, they do not even realize that the weather is good. the weather, as a factor, comes to people's mind when it goes wrong. the weather and the climate is a key factor in tourism (perry, 1997). there are multiple interactions between tourism and climate systems. first, the weather and climate can be limiting factor in tourism (de freitas, 2003; matzarakis, 2006). all regions have a tourism potential and appeal determined by the weather and climate. if a region’s climate is optimal for tourism, the area has great appeal (fig.1). this also means that there are some areas on the world where the climate is unsuitable for tourist activities. the most tourist activity has climatic constraints or limiting factors (as an example, the appropriate quantity and quality of snow are essential for ski-tourism). this implies that those areas where the terms of tourism activities are lacking have lower appeal. in such areas the tourism is more or less risky. this risk can be either financial or physical. secondly, the climate and weather can be also dominating factor in tourist demand (de freitas, 2003; matzarakis, 2006). the climatic conditions affect the tourists’ decision on destination selection and mainly their time of travelling. however, the actual meteorological conditions influence the tourists what activities will be carried out in reality. finally, the climate and weather can be risk factor for human health because the trips in extreme climate areas may cause health problems (heat stroke, sunburn, asthma attack caused by air pollution, frostbite or other cold-related injury, etc.) (matzarakis, 2006). 50 németh (2013) fig. 1 schematic representation of relationship between a climatic range and tourism potential. the climate potential of a particular location is a function of its climate and of the risks that weather may impose. (de freitas, 2003 after perry, 1997). tourism climate of a given area can be approached from several aspects. some climate parameters are evaluated by physical (e.g. rain, air pollution), some by aesthetic or psychological (e.g. “clear blue sky”), while others by physiological (e.g. air temperature) aspect. one might think that the thermal component is the most important factor in terms of the tourism climate. but, if a region's temperature is in an acceptable range, the importance of the other factors increases in the tourism climatological evaluation. let’s examine some of these factors. physical factors are those meteorological parameters which affect the tourists' satisfaction directly or indirectly. as an example, the occurrence of a heavy rainfall during holidays has a direct impact on tourists which causes inconvenience (e.g. getting clothes or luggage wet), or affect indirectly the level of satisfaction (e.g. poor quality photos can be made). physical factors include wind, ice and snow, severe weather conditions, or even the uv-rays. the aesthetic (or psychological) aspects influence especially the attractiveness of the region and the enjoyment of holiday. this category includes the visibility, the cloudy or sunny day determined by the synoptic situation, and the length of the day. the thermal aspects play role on the characterization of thermal comfort during the holidays. this means not only the air temperature, but the combined effect of temperature, humidity, solar radiation and wind. the tourism climatology aims to examine and clearly demonstrate the above-mentioned characteristics for both tourists and tourism operators. determining the tourism climate, simple climatic or bioclimatic indices were formerly used. nowadays, more than 200 such indices exist. according to matzarakis (2006), the tourism climatic indices can be divided into three categories. for calculating the elementary indices, one or more meteorological data are needed which do not contain any thermo-physiological information thus they do not really work in practice. the bioclimatic and combined indices include several climatic and bioclimatic parameters and their combined effect is taken into consideration. some examples of the tourism climatic indices are shown in table 1. table 1 examples of tourism climate indices (after matzarakis, 2006) category parameters included elementary air temperature, sunshine duration, precipitation bioclimatic windchill (air temperature and wind speed) bioclimatic indices (based on human energy balance) – e.g. predicted mean vote (pmv)*, standard effective temperature (set)*, physiologically equivalent temperature (pet)* combined combination of parameters: daytime comfort index**, daily comfort index**, precipitation, sunshine duration, wind speed, pmv, pet * definitions of these bioclimatic indices are in fanger (1970), gagge et al. (1986), mayer and höppe (1987) ** for definitions of these indices see section “tourism climatic index” materials and methods used data in this study the measured meteorological data of the storm warning observatory in siófok (46°54’n, 18°02’e, 108 m asl) were used (fig. 2). the measurements take place at the same location since the 1950's, so the data series do not have displacement-caused inhomogenity. this is particularly important for analyzing the long-term data series. the meteorological station is located right at the lakeside, thus it is ideal for tourism climatology. in the calculations the following measured data (for period 1961–2010) were utilized: hourly air temperature, relative humidity, vapourpressure, wind speed, cloudiness; daily precipitation sum, average sunshine duration and daily maximum of wind speed. applied methods 1) tourism climatic index (tci) there are several ways to determine the extent of the suitability of an area for tourism purpose in a climatic point of view. several attempts have been made to identify the best or the optimal climate conditions for a tourism activity. two of such methods were utilized in the present study. first, one of the best-known and most widely used combined indices, the tourism climatic index (tci) was used. the tci is favoured as an index because it is one of the most comprehensive metrics, integrating all three facets of climate considered relevant for tourism (perch-nielsen et al., 2010). the tci was originally devised by mieczkowski (1985) to exactly evaluate the climatic variables which are the most relevant for the quality of tourism experience of the “average” tourist. this work is based on the previous researches on relation between climate classification estimation of tourism climate in the lake balaton region, hungary 51 and recreation, and applied the human comfort-related outcomes too (amelung and moreno, 2012). the original index included 12 monthly climate variables. the final version of tci was integrated only seven climatic variables (more precisely monthly averages of them): daily mean temperature, daily maximum temperature, daily mean relative humidity, daily minimum relative humidity, daily precipitation sum, daily sunshine duration and daily mean wind speed. these seven climatic variables were combined into five sub-indices (table 2). a standardized rating (from the very bad of –3 to the very good of 10) system was devised to provide a common basis of mea surement for each of the sub-indices. in human biometeorological practice, many comfort indices exist for characterizing thermal comfort. accordingly, the calculation of daily and daytime comfort index, which is included in the equation, can be done in several ways. the thermal comfort – in a subjective approach – is a kind of positive opinion (satisfaction), which expresses our relationship to the ambient thermal conditions. this subjective sensation is influenced basically by four meteorological factors: air temperature, relative humidity, wind speed and solar radiation. however, the effective temperature (et) in its original form – which was applied by mieczkowski (1985) for calculating the tci – determines the combined effect only of the air temperature and air humidity (hajek and espinosa, 1982). et is defined as the temperature of the saturated and stationary air mass which results the same total heat loss from the skin, and therefore the same thermal co mfort sensation, as the actual environment. a serious pro blem with this definition of effective tempe rature is that it makes no special allowance for radiation. the tourism climatic index is calculated as follows: tci = 8·cid + 2·cia + 4·p + 4·s + 2·w (1) where: cid = daytime comfort index cia = daily comfort index p = precipitation s = sunshine w = wind speed based on a location’s index value, its suitability for tourism activity is then rated on a scale from –30 to 100 (table 3). mieczkowski (1985) divided this scale into fig. 2 geographical location of the lake balaton region in hungary and the examined meteorological station (siófok) table 2 sub-indices and their relative contribution to the tci sub-index climate variables influence on tci weight ing in tci daytime comfort index (cid) maximum daily temperature and minimum daily relative humidity represents thermal comfort when maximum tourist activity occurs 40% daily comfort index (cia) mean daily temperature & mean daily relative humidity represents thermal comfort over the full 24-hour period, including sleeping hours too 10% precipitation (p) daily precipitation sum reflects the negative impact that this element has on outdoor activities and holiday enjoyment 20% sunshine (s) daily hours of sunshine duration acknowledged can be negative because of the risk of sunburn and added discomfort on hot days 20% wind (w) daily averaged wind speed variable effect depending on temperature (evaporative cooling effect in hot climates rated positively, while ‘wind chill’ in cold climates rated negatively) 10% 52 németh (2013) ten categories, ranging from “ideal” (90 to 100), “excellent” (80 to 89) and “very good” (70 to 79) to “extremely unfavourable” (10–19) and “impossible” (–30 to 9). in this study, a tci value of 70 or higher is considered attractive for the “typical” tourist engaged in relatively light activities such as sight-seeing and shopping. table 3 tourism climatic index rating system (mieczkowski 1985) numeric value of tci description of comfort level for tourism activity 90 – 100 ideal 80 – 89 excellent 70 – 79 very good 60 – 69 good 50 – 59 acceptable 40 – 49 marginal 30 – 39 unfavourable 20 – 29 very unfavourable 10 – 19 extremely unfavourable below 9 impossible 2) climate-tourism-information-scheme (ctis) although the mieczkowski's tci distributed worldwide as a tourism climate index, it has numerous limiting factors while using it. the most serious limitation of the tci is its subjectivity and lack of verification (perchnielsen et al., 2010). the effective temperature which is used to determine the daily and daytime comfort index is an outdated bioclimatic index. on the other hand, the tci gives information about tourism climate in very poor temporal resolution. therefore it has become necessary to develop a system, which can characterize a region's tourism climate in fine temporal resolution by using a modern, energy balance-based bioclimatic index. one of the latest possibilities for the integration of climate/bioclimate information for tourism purposes is the climate-tourism-information-scheme (matzarakis, 2007; zaninović and matzarakis, 2009). it represents frequencies and probabilities of different bioclimatic and tourism climatic factors from all facets. this method is particularly suitable for the analysis of selected destinations and therefore the tourist practice – policy makers and planners – in high spatial and temporal resolution climate information. therefore the ctis is not a tourism climatic index. actually, the ctis is a graphical representation of the tourismrelevant climatic information in high temporal resolution of 10 days – each month is divided into three time intervals (matzarakis et al., 2012). the advantage of 10-day intervals is that it is roughly equal to the average duration of vacation time. meanwhile the ctis is a flexible system. in this case, the flexibility means that it can be selected one by one those climatic parameters which are relevant for a specific tourism sector in a specific region. for tourism in lake balaton region the next ctis factors are selected: cold stress (physiologically equivalent temperature i.e. pet<0°c), heat stress (pet>35°c), thermal comfort (18°c<pet<29°c), sunshine/cloud cover conditions in terms of the number of days with a cloud cover < 5 octas, vapour pressure > 18 hpa, relative humidity > 93%, precipitation < 1 mm as well as precipitation > 5 mm, and wind speed > 8 ms –1 as well as wind speed > 17 ms –1 . in general, the definitions of the several threshold values do not necessarily correspond to the universal meteorological threshold values and are adjusted to applied tourism climatology and human health applications. for the calculation of the thermal component of ctis, the physiologically equivalent temperature (pet) was used. it is one of the most common bioclimate indices, which is derived from the munich energy-balance model for individuals (memi) (höppe, 1984, 1999). the memi models the thermal conditions of human body in a physiologically way. beside of meteorological parameters (air temperature, relative humidity, wind speed and cloudiness) some physiological and geographical inputs are required for calculating pet. for the calculation the rayman software was used (matzarakis et al., 1999, 2007). the calculation was taken on a 35 years old, 75 kg weight and 175 cm high man, who is sitting and wears normal clothing (0.9 clo). the categories of pet values were defined according to different thermal perceptions for temperate climate (table 4). table 4 categories of physiologically equivalent temperature (pet) for different levels of physiological stress and thermal sensation (matzarakis and mayer, 1996) pet (°c) grade of physiological stress thermal sensation above 41 extreme heat stress very hot 35 to 41 strong heat stress hot 29 to 35 moderate heat stress warm 23 to 29 slight heat stress slightly warm 18 to 23 no thermal stress comfortable 13 to 18 slight cold stress slightly cool 8 to 13 moderate cold stress cool 4 to 8 strong cold stress cold below 4 extreme cold stress very cold results and discussion fig. 3 shows the monthly values of tci for three climatological normal periods (1961–1990, 1971–2000 and 1981–2010) in siófok. the many-years averages of tci were 60.5, 61.5 and 61.8 in the three examined periods. based on this, the region's tourism climate potential is good. the diagrams show clearly, that the tourism climate of the lake balaton has a summer peak. the high estimation of tourism climate in the lake balaton region, hungary 53 est values (tci ≥ 80) occur during the summer months, but altogether, the period from "good" to “ideal” lasts from may to september. the climatic requirements of tourism are not appropriate (“unfavourable”) only in two months (december and january), but the tci values do not go below 30 in these months. examining each climate periods it can be concluded, that there was no significant change in the climatic terms of the tourism in the last half-century in the studied region. the averages of tci increased significantly only in february and june. the latter means the prolongation of the bath season in summer. the change of tci can be examined in more detail by analyzing the changes of sub-indices. significant differences could not be explored between the two 30year periods with 20-year difference by examining fig. 4. however, some small characteristics can be observed. in february, the more favourable daytime comfort and precipitation conditions cause higher values of the tci. this change in climate comfort can also be observed in may. in june, however, especially the aesthetic and physical components of the tourism climate changed favourably. the greatest change occurs in the wind conditions – this sub-index increased by 4 points. based on the ctis diagrams (fig. 5 and fig. 6), from a thermal point of view, the favourable period (when the pet value is between 18 and 29°c) lasts from early may until the first third of october. interesting that in contrast to the tci graphs, we can talk about two-peak tourism season based on ctis. the highest frequency of thermal comfort occurs in the end of may and in the middle of september. the rate of the comfort periods decreases temporarily during the summer months; this ratio is close to 30% in late july and early august. heat stress (pet>35°c) should be expected typically in the summer months. the warmest period lasts from middle of july until beginning of august, when the highest frequency of heat stress occurs. although, it should be noted, that the bathing potential of the area offset or makes it easier to endure these circumstances. the cold-stressed periods are frequent between mid-december and the end of january. the sultriness which is an important parameter in the thermal aspect reaches its maximum in early august, when the probability of these weather conditions is 50–60%. comparing the period of 1961–1990 and fig. 3 the 30-year averages of the monthly means of mieczkowski’s tourism climatic index in siófok fig. 4 the 30-year averages of the monthly means of sub-indices of tci in siófok for the period of 1961–1990 (left) and 1981–2010 (right) 54 németh (2013) 1981–2010, the above mentioned characteristics have become stronger, but the length of the tourism season did not change significantly. the frequency of sunny days (according to the criteria) is favourable in terms of waterside tourism. its ratio is above 50% during the period from april to october, but in july and august this ratio is close to 70–80%. foggy weather can be expected from september to april, but its relative frequency of more than 20% is only in december and the first half of january. examining the two 30-year periods, significant change can be seen especially in sunny days. the period of the sunny days increased in all seasons except in winter. this indicates the positive changes in the aesthetic component of the region's tourism climate. the physical factors influence the region's tourism climate in a positive direction as a general rule. the precipitation and wind do not worsen the comfort sensation of the tourists. in this regard, there is no significant change between the two climate normal periods. the ctis diagrams confirm the empirical fact that the climate of lake balaton is appropriate for lakeside tourism and other outdoor activities in the warmer half of the year. fig. 5 ctis (percent-type) in siófok for the period of 1961–1990 (upper) and 1981–2010 (lower) fig. 6 ctis (assessment-type) in siófok for the period of 1961–1990 (upper) and 1981–2010 (lower) estimation of tourism climate in the lake balaton region, hungary 55 conclusions tourism climate is generally described by air temperature, precipitation and sunshine duration. although these parameters are important, they do not describe the tourism climate potential of an area appropriately. therefore, the tourism purpose examinations necessary to use such integrated indices or rating systems which take into account all the components of the tourism climate (physical, aesthetic and thermal). this paper means a step forward in this regard, because tourism climatological analyses with similar approach are not made previously. the results presented here can be easily interpreted for the travelling public and tourism operators. the mieczkowski's tci index shows that the lake balaton region's climate potential is favourable. the region has a positive climate for the lakeside tourism and other outdoor activities, especially in summer. the observed changes are insignificant over the past halfcentury; the climate potential only hardly changed. however this does not means that the future changes in the climate does not may cause a marked changes in the region's tourism climate. these analyses have to be carried out towards sustainable tourism development. recent studies have shown that the region's climate supports only slightly the possibility of extending the tourist season. although the tci is primarily developed for the analysis of urban tourism, it can be used almost in all sectors of the tourism industry. the tci can be widely used because easy to calculate and does not require specific input data. in the future, however it would be advisable to examine that instead of the thermal co mfort index (effective temperature), which is used in tci, can be applied to other, modern bioclimatic index based on human energy balance (eg. physiologically equivalent temperature). based on ctis, the region's tourism climate potential pattern is slightly different, it is rather bimodal. this is probably due to the ctis factors were selected accordingly the tourism of this region (beach or lakeside tourism). over the past 50 years, changes were appeared in the thermal and aesthetic (sunshine duration) components. in summer, the change in heat stress and sultriness may affect negatively to the tourism in the region. at the same time, the increase in sunshine duration assists to the beach tourism. on the whole, the tourism climate potential of lake balaton region rose slightly over the past 50 years due to the changing climate. comparing the classic tci with the ctis, it should be highlighted the better temporal resolution and a more detailed criteria-system of the ctis. the 10-days resolution of ctis is near to the average length of stay of visitors. acknowledgements many thanks to jános unger for his comments and suggestions at the preparation stage of the manuscript. in addition i would like to express my thanks to attila kovács for the language revision of the manuscript. references amelung, b., moreno, a. 2012. costing the impact of climate change on tourism in europe: results of the peseta project. climatic change 112 (1), 83–100. de freitas, c.r. 2003. tourism climatology: evaluating environmental information for decision making and business planning in the tecreation and tourism sector. international journal of biometeorology 48, 45–54. fanger, p.o. 1970. thermal comfort. danish technical press. copenhagen, 244 p. gagge, a.p., fobelets, a., berglund, l.g. 1986. a standard predictive index of human response to the thermal environment. ashrae transactions 92, 709–31. hajek, e.r., espinosa, g.a. 1982. biometeorología humana: algunos conceptos y proyecciones. archivos de biología y medicina experimentales 15, 501–512. höppe, p. 1999. the physiological equivalent temperature in an universal 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(ed.) applied climatology – principles and practice. routledge, abingdon, 240–248. zaninović, k., matzarakis, a. 2009. the bioclimatological leaflet as a means conveying climatological information to tourists and the tourism industry. international journal of biometeorology 53, 369–374. journal of environmental geography journal of environmental geography 7 (3–4), 39–47. doi: 10.2478/jengeo-2014-0005 issn: 2060-467x environmental changes in historical times near apostag on the danube-tisza interfluve, hungary (a complex research based on archaeological excavation and geomorphological investigations) diána nyári 1* , istván knipl 2 , györgy sipos 1 , tímea kiss 1 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 museum of kiskunfélegyháza, dr. holló lajos u. 9, h-6100 kiskunfélegyháza, humgary *corresponding author, e-mail: nyaridia@gmail.com research article, received 26 february 2014, accepted 31 march 2014 abstract the sensitive, partly fixed dune areas are good indicators of alteration, since they react rapidly to changing environmental conditions. due to the climate changes, especially the increased aridity during the holocene, many blown sand areas became active. later, humanity had increasing impact of on its environment, thus sand movements occurred due to anthropogenic activities. aeolian activities were identified not only in the historical times but also a few decades ago, when the moving sand caused significant problems on surfaces becoming bare. the present work will provide good evidence on sand movement in historical times caused by human impact on the environment with the help of osl dating and archaeological research in the vicinity of the town of apostag, which is located on the largest blown-sand area of hungary on the danube-tisza interfluve. the aims of the research were to identify the ethnical groups and their possible activities; to map the geomorphology of the study area; to determine the periods of aeolian activity; to assign the possible types of human activities in connection with climatic changes enabling aeolian activity. keywords: environmental changes, optically stimulated luminescence, archaeology, geomorphology, blown sand movement introduction the sensitive, partly fixed dune areas are good indicators of alteration, since they react rapidly to changing environmental conditions. it can be confirmed by the result of an australian survey where sand sheet was detected in a fixed dune area covered by forests due to sand movement in the early holocene. the palinological investigations did not confirm aridification in the area; the precipitation increased continuously after the pleistocene and reached the maximum 4000 years ago (shulmeister, 1992; shulmeister and lees, 1992). however, the presence of the dry period is confirmed by many proofs; the change was probably so rapid and the dry period lasted so shortly that its influence could not be detected in the pollen spectrum (nott et al., 1999). therefore, the investigation of sand movement has an important role in the assessment of environmental impacts, since small changes can modify the sensitive balance and can indicate mobilisation. due to the climate changes, especially the increased aridity during the holocene, many blown sand areas became active e.g. in the united states (forman et al., 1992, 1995; olson et al., 1997; rawling et al., 2003; stokes and swinehart, 1997; wilkins and currey, 1999). on the european coastal areas climate change due to the little ice age indicated sand movements (borja et al., 1999; clarke et al., 2002, wilson and braley, 1997; wintle et al., 1998). forest fires also resulted in bare surfaces where wind erosion could become dominant (filion, 1984; filion et al., 1991; kayhkö et al., 1999). later, humanity had increasing impact of on its environment, thus sand movements occurred due to anthropogenic activities (wilkins and currey, 1999; wilson and braley, 1997; wintle et al., 1998). thus, the investigation of holocene sand movements has an important role in the assessment of global warming, climate change and the human impact on the environment. sand movements were identified not only in the historical times but also a few decades ago, when the moving sand caused significant problems on surfaces becoming bare. in ireland the improper land use in the 1930-40s caused the degradation of cultivated areas, and the huge amount of sand blocked roads (wilson and braley, 1997). increased aeolian activities were identified in canada in the 1920-30s (lemmen et al., 1998), furthermore during the 1980s as well (david and wolfe, 1997). huge damages were also reported in the usa in the beginning of 1930s due to wind erosion (orlove, 2005). sand movements caused significant damages in the lack of vegetation on the surface also in hungary (mezősi and szatmári, 1998; szatmári, 2004). according to borsy (1972) 5-40 cm thick sand layers was transported during a few days south-east from kiskunhalas in april 1967. significant damages due to deflation on sandy surfaces were recorded from nyírség region between 10 and 12 february 1984 (lóki, 1985). 40 nyári et al. (2014) climate change, growing population, the development of agricultural techniques and the changes in land use caused human induced environmental changes, which became increasingly significant in history. good examples can be found in hungary on the da nube-tisza interfluve where both the change in clima tic conditions and the anthropogenic disturbance caused aeolian activity during historical times. ther efore, the geomorphology of the area transformed and the pleistocene forms were reshaped by holocene sand-movements. the earliest blown sand movements on the danube-tisza interfluve took place in the inter pleniglacial of the pleistocene (sümegi and lóki, 1990; sümegi, 2005) and subsequently there was aeolian activity during the middle pleniglacial of the pleistocene after 25 200 ± 300 year ago (krolopp et al., 1995; sümegi, 2005). according to earlier researches on the danube-tisza interfluve the most significant aeolian activity occurred during the upper pleniglacial (borsy, 1977ab, 1987, 1989, 1991; sümegi et al., 1992; sümegi and lóki, 1990; sümegi, 2005). later, the two cold and dry periods, the older dryas and younger dryas in the pleistocene were co nvenient for aeolian rework (borsy et al., 1991; hertelendi et al., 1993) which is supported by radiometric, optical and thermo-luminescenece measurements too (gábris et al., 2000, 2002; gábris, 2003; újházy, 2002; újházy et al., 2003). sand dunes, formed under cold and dry climate in the pleistocene, were gradually fixed as the climate changed to warm and humid during the holocene. however, researchers draw attention to the possibility of sand movement in the holocene too. the warmest and driest holocene phase (boreal phase) was the most adequate for dune formation (járainé, 1966, 1969; borsy, 1977ab, 1987, 1991; gábris, 2003; kádár, 1956; marosi, 1967; újházy et al., 2003), though, certain investigations claim that the second half of the atlantic phase could also be dry enough for the remobilisation of sand (járainé, 1966, 1969; borsy and borsy, 1955; borsy, 1977ab; gábris, 2003; újházy et al., 2003). nevertheless, the latest, usually local signs of aeolian activity can be related to various types of human impact. former investigations consider that sand movement could occur during the turkish occupation (16 th 17 th century ad) and subsequently in the 18 th -19 th century ad due to deforestation (borsy, 1977ab, 1987, 1991; marosi, 1967). based on archaeological investigations and osl measurements on the danube-tisza interfluve aeolian activity occured in the bronze age (gábris, 2003; újházy et al., 2003; nyári and kiss, 2005a, b; kiss et al., 2006; nyári et al., 2006, 2007a and b; sipos et al., 2006), then the surface became stable for a long period, until the 3 rd -4 th centuries ad. as later the climate turned dry (rácz, 2006; persaits et al., 2008) and the anthropogenic disturbance became more significant conditions became suitable for aeolian activity, which is proved by several researchers (lóki and schweitzer, 2001; kiss et al., 2006; nyári et al., 2006, 2007a, b; sipos et al., 2006). sand movement was also characteristic in the migration period, especially during the 6 th 8 th century ad, which was the realm of the avars (nyári and kiss, 2005a,b; kiss et al., 2006; nyári et al., 2006, 2007a, b; sipos et al., 2006) subsequent aeolian activity occurred also in the árpád age (11 th -13 th c. ad, lóki and schweitzer, 2001; gábris, 2003; újházy et al., 2003; nyári et al., 2006) and when the cumanians inhabited the territory (13 th c. ad, sümegi, 2001; kiss et al., 2006; nyári et al., 2006, 2007a, b; sipos et al., 2006). the latest aeolian activity occurred in the 15 th century ad (nyári et al., 2007a). the present work will provide good evidence on sand movement in historical times caused by human impact on the environment with the help of osl dating and archaeological research in the vicinity of the town of apostag, which is located on the largest blown-sand area of hungary on the danube-tisza interfluve. the aims of the research were to identify the ethnical groups and their possible activities; to map the geomorphology of the study area; to determine the periods of aeolian activity; to assign the possible types of human activities in connection with climatic changes enabling aeolian activity. study area the study area is located on the west part of the da nube-tisza alluvial fan, south from apostag (fig. 1.). the archaeological sites are situated on the south part of the study area (fig. 8.). methods archaeological investigations the archaeological investigations enabled to determine the historical characteristic of the study area and to assign the activity of the seated people who inha bited the area. geomorphological mapping the relief and geomorphological map of the investigated area was compiled on the basis of field mea surements and 1:10,000 scale topographic maps. forms typical on stabilised blown-sand areas were allocated — blowout depressions, blowout ridges, hummocks, and the brink lines of dunes — and also former flows could be determined. osl measurements four samples were collected from two profiles. extraction and sample preparation procedures followed the steps introduced by aitken (1998) and mauz (2002) and aimed at the separation of quartz grains of suitable (90-150 µm) size. measurements were made on an automated risoe tl/osl-da-15 type luminescence reader. throughout the measurements the sar technique, described in detail by murray and wintle (2000), was followed. environmental changes in historical times near apostag … 41 results archaeological research during rescue excavation on the area about 300x25 meters 34 chases, 38 holes, 15 pile holes, 3 pits, nine graves from the sarmatian era as well as a modern pit were explored. the objects of the settlement were sometimes dug on each other, and often they formed small groups and were situated quite rarely. the e xcavated area was arranged into well segrega ted parts. on the western part next to an expansive ditch system, on stock-raising referring hurdle ditches and pits showed up, in the middle another large ditch system, and on the eastern part scarce marks of settlement and a few graves of the cemetery were founded (fig. 2). on the western edge of the rescue excavated area, close to the animal keeping hurdles three middle sized pits were excavated, which included no rateable appendices; only in one of the pits a skeleton of a dog was found (fig. 3). in addition on the middle of the area a stock-yard was found (fig. 2). fig. 1 location of the study area fig. 2 the archaeological site and the excavated features 1: pit, 2: stock yard, 3-5, 25-27: ditches 42 nyári et al. (2014) fig. 3 skeleton of a dog in the examined area various ditches could be observed. firstly there were extensive hurdle ditches connected to the animal keeping part of the settlement; furthermore, large sections of ditch systems could be observed, which were probably used for some kind of defence of the settlement. the most western parts of one of the ditch systems were the ditches nr. 5. and 4. the narrow, shallow ditch nr.4 followed the line of the ditch nr. 5. (fig. 2). the 2 m wide, variable deep, arranged bottomed 5. ditch cut the excavated area in northwestsoutheast direction across. its cutting was extremely interesting: in almost its whole length in both sides of the ditch there was a sinking: it was 20-30 cm wide and came down with the same depth under the bottom level of the ditch, which is supposed to be the basic ditch of the pile lines on both sides of the ditch (fig.4). the other great, with the previous parallel ditch system formed by the ditches 25-26-27, turned up about 40-45 m from the ditches 4-5 (fig. 2). the depth of the three parallel and approaching ditches were remarkably distinct. fig. 4 ditch nr. 5 the middle and the eastern (26-27.) ditches had arranged bottoms, but according to the pruned surface they were shallow, however the ditch nr. 25 ended about 80 cm from the pruned level. its width was about 200 cm; its lateral wall was upright, partly splay, and its bottom was mainly straight. the speciality of this ditch system is that with the sudden “jumping up” of the ditch bottom it became really shallow on a 15 m long stage. while there is no mark on a subsequent infilling of the ditch, we recognise the shallow part as the part of the original ditch. the explanation can be that there might be some kind of entrance or passage through the ditch (fig. 5). according to the air photo made on the area the ditch system can be followed on few hundred meters. in the long run we can assume only generally, that it might be a part of a significant fortification-ditch defence system (fig. 6). fig. 5 ditch nr. 25 the air photos show not only the great fortification system but also a wide cemetery (fig. 6). on the eastern end of the excavated area nine graves were rescue excavated, with and without round-ditch (fig. 2.). the nwse sited graves were dominantly close to each other. it is remarkable that graves without round-ditches were immediately next to those with round-ditch, close to each other, in a row. usually young deceased were buried in those graves, while in the round-ditched graves rather adults (fig. 7 a, b). most of these were robbed. environmental changes in historical times near apostag … 43 the artefacts of untouched graves allowed of an interesting observation on costume history. in two graves a significant amount of different coloured pastry beads were found (fig. 7c). the beads were in rows, in the front part of the neck and on the wrist, so they might be the decoration of the neck and sleeve of the clothes. in the graves some brazen and silver fibulas, mostly close to the breastbone, were found and next to one skeleton there were two fib ulas under each other. other grave artefacts are: two brazen earrings, one brazen ring, one spindle knob, fragments of two small pots, fragments of an iron knife and iron sword, together with a coin from r oman age (aurelianus: 270-275). geomorphological mapping the mapped area is 4 km 2 and situated on the western part of the danube-tisza interfluve 2.5 kilometers from the danube river on the border line b etween a stabilized blown sand surface and a former floodplain of the danube river (fig. 1). the altitude of the area varies between 94 and 102 m asl. in the middle a sand deposit can be seen which has been blown there by the wind from the deposited sand of the danube river. this higher sandy place is bordered by low lying, flat areas (fig. 8). based on the relief map the centre of the investigated area represents an accumulation zone, fig.6 air photo of the excavated area and its neighbourhood a. b. c. fig. 7 a: robbed adult grave; b: a round ditch; c: untouched grave with artefacts 44 nyári et al. (2014) where according to the geomorphological mapping the most typical forms are blowout de pressions, blowout ridges and blowout dunes (hummocks). around this higher sandy surface low lying, flat, former alluvial areas of the danube river can be identified (fig. 9). the holocene morphological evolution of the investigated area is complex. in most of the cases pleistocene forms were reshaped and transformed, thus at certain locations the orig inal morphology can hardly be identified. remobil isation and reshaping was especially intensive during historical times, however it was restricted to smaller patches of land. depositional history samples were collected at two locations ( fig. 8). profiles show the types of different depositions a nd osl ages (fig. 10). based on the results, osl yielded early holocene age for the lowermost layer (9094 ± 1096 bp), on which sequences of fluvial deposits, paleosoils and blown-sand layers were formed during the holocene. initially fluvial pr ocesses were characteristic on the territory. the danube river deposited carbonate silt on the surface. when the danube left this area and drifted to west a thick paleosoil was formed on the fig. 8 the relief of the study area, the archaeological sites and the sampling places fig. 9 the geomorphological setting of the study area environmental changes in historical times near apostag … 45 surface. paleosoil is superimposed by blown -sand layers of varying thickness in the profiles the first phase of sedimentation occurred 1765±189 y bp. later aeolian activity restarted two times again, first 982 ± 218 y bp then 851 ± 146 y bp, according to osl measurements conclusion age and sedimentological data of the profiles were compared to archaeological evidence, the spatial di stribution of findings of the site (wicker 2005), as well as archaeological relicts from the area of apostag (kjm 1968, 1976, 1985, 2001, 2005). this enabled the reconstruction of the type, intensity and the result of human impact on the paleo-environment. all age data were plotted on a historical timescale (fig. 11) according to the archaeological evidences, people settled down on the paleosoil surface. they were sarmatians who inhabited the area between the 1st and 4th century. they were farmers and they also kept livestock on the pastures. the excavated marks of trenches and stock-yards prove that the excavated site probably functioned as a stock farm and the neighbouring mounds have been pastures or meadows. this is confirmed by the osl measurements, as blown sand movement was detected on the nearby higher places in the 3rd century ad (osl: 1765 ± 189 bp). probably the cause was ploughing or over-grazing resulting bare surfaces, which were scenes of wind erosion. finally, a 60-70 cm sand sheet covered the paleosoils of neighbouring mound. on the evidence of the archaeological investigations, later, in the árpád age a larger population lived on the territory of the study area and their activity meant an intensive burden on the environment. b e fig. 10 profiles of the sampling places, depositions and osl data fig. 11 osl ages and the archaeological relicts of the area of apostag 46 nyári et al. (2014) cause of the human impact, aeolian activity revealed again in the 11 th century ad (osl: 982 ± 218 bp) and a 20-30 cm thick sand sheet covered this time the former surface of the excavated site then a poorly developed soil was formed. afterwards during the 12 th century (osl: 851 ± 146 bp) blown sand movement happened over again and another 60-80 cm thick sand layer covered the territory of the excavated area. as a conclusion, there was three times spatially localized blown-sand movement on the study area. the first movement effected a sand deposition on the next mound from the archaeological site because of the activity of sarmatians then two times blown sand movements covered the area of the site by sand sheets as a result of anthropogenic disturbance in the árpád age. thus, former landscape has been changed. today the surface is approximately 1 m higher than before and a sandy surface can be found where a thick paleosoil was situated before. acknowledgements this research was supported by the european union and the state of hungary, co-financed by the european social fund in the framework of támop 4.2.4. a/2-11-12012-0001 ‘national excellence program’. references aitken m.j. 1998. an introduction to optical dating: the dating of quaternary sediments by the use of photon-stimulated luminescence. oxford: oxford university press borja, f., zazo, c., dabrio, c.j., díaz del olmo, f., goy, j.l., lario, j. 1999. holocene aeolian phases and human settlements along the atlantic coast of southern spain. the holocene 9 (3), 333–339. doi: 10.1191/095968399668924476 borsi, z-né, borsy, z. 1955. pollenanalitikai vizsgálatok a nyírség északi részében. közlemények a klte földrajzi intézetéből 22, 1–10. borsy z. 1977a. a duna-tisza köze homokformái és a homokmozgás szakaszai. alföldi tanulmányok 1, 43–53. borsy, z. 1977b. a magyarországi futóhomok területek felszínfejlıdése. földrajzi közlemények, 12–16. borsy, z. 1987. az alföld hordalékkúpjainak fejlődéstörténete. nyíregyházi főiskola füzetek, 5-37. borsy, z. 1989. az alföld hordalékkúpjainak negyedidőszaki fejlődéstörténete. földrajzi közlemények 211–222. borsy, z. 1991. blown sand territories in hungary. zeitschrift für geomorphologie n.f. suppl. 90, 1–14. borsy, z., félegyházi, e., hertelendi, e., lóki, j., sümegi, p. 1991. a bócsai fúrás rétegsorának szedimentológiai, pollenanalitikai és malakofaunisztikai vizsgálata. acta geographica debrecenina, tomus 28–29, 263–277. clarke, m., rendell, h. tastet, j-p., clavé, b., massé, l. 2002. lateholocene sand invasion and north atlantic storminess along the aquitaine coast, southwest france. the holocene 12 (2), 231– 238. doi: 10.1191/0959683602hl539rr filion, l. 1984. a relationship between dunes, fire and climate recorded in the holocene deposits of quebec. nature 309, 543–546. doi: 10.1038/309543a0 filion, l., saint-laurent, d., desponts, m., payette, s. 1991. the late holocene record of aeolian and fire activity in northern quebec, canada. the holocene 1, 201–208. doi: 10.1177/095968369100100302 forman, s.l., goetz, a.f.h, yuhas, r.h 1992. large-scale stabilized dunes on the high plains of colorado: understanding the landscape response to holocene climates with the aid of images from space. geology 20, 145–148. doi: 10.1130/0091-7613(1992)020<0145:lssdot>2.3.co;2 forman, s.l., oglesby, r., markgraf, v., stafford, t. 1995. paleoclimatic significance of late quaternary aeolian deposition on the peiedmont and high plains, central united states. global and planetary change 11, 35–55. doi: 10.1016/09218181(94)00015-6 gábris, gy., horváth, e., novothny, á., ujházy, k. 2000. environmental changes during the last -, lateand postglacial in hungary. in: kertész, á., schweitzer, f. 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szatmári and van leeuwen, 2013). three main reasons can be identified to study iew. it is studied to (1) understand the interrelated factors and processes that cause the formation of inland excess water, (2) to determine the location and size of the inundations to be able to take operative measurements to mitigate and prevent further damage, and (3) to forecast the location, size and duration of future floods to develop preventive policies (van leeuwen et al., 2016). four general approaches have been applied to study the development, extent and duration of iew inundations. first, in hungary, since the second half of the 20th century, at national scale the extent of iew was measured by observations in the field. these observations are labour intensive and therefore expensive. they are error prone due to differences in observation and interpretation techniques and they are usually performed infrequently, so they give an overview of the maximum extent of the flood, but it is not possible to use them for monitoring purposes. the second approach uses geographic information systems to combine many factors related to the development of iew, to create maps describing the vulnerability of areas to the inundations. these maps are normally made at regional scale, which is the scale of most of the input data (pálfai, 2003; bozán et al., 2005; bozán et al., 2009; pásztor et al., 2014). vulnerability maps provide information on the general probability that somewhere iew will occur, but do not give information about the actual occurrences, nor about the development of the phenomenon. the third approach is the application of complex distributed models to simulate the hydrological processes causing iew. since this technique requires large amounts of very detailed input data, it is only feasible to use it at a small area. depending on the quality of the input data, the technique can provide accurate information on the occurrence, extent and progress of iew. it may also be able to forecast where iew may occur (van leeuwen et al., 2016). the last approach to the problem of iew is the use of remote sensing data. in the past 30 years, studies have been published using aerial photographs (licskó et al., 1987; rakonczai et al., 2001; van leeuwen et al., 2012), multispectral satellite data (csornai et al., 2000; rakonczai et al., 2001; mucsi and henits, 2010) and hyperspectral data (csendes and mucsi, 2016). also, some experiments have been executed using active satellite data (csornai et 10 van leeuwen et al. (2017) al., 2000; csekő, 2003; gálya et al., 2016). the use of remote sensing techniques allows for the acquisition of data of medium (aerial photographs) to large areas (satellite data). well understood processing techniques like classification and segmentation allow for the standardized processing of data and provide unified results over large areas. common disadvantages of satellite data are their low temporal resolution and the limited availability of multispectral data due to bad atmospheric circumstances. also, the resolution of non-commercial data was sometimes not suitable for iew studies. in 2014, as part of its copernicus program, esa started to launch the first satellites in its sentinel earth observation constellation (malenovský et al., 2012). the data from the satellites is made publicly available free of charge and without restriction of use. with the formation of the sentinel satellite constellations, to a large extent, the earlier disadvantages of satellite data can be overcome. for iew monitoring, two types of satellites in the constellation are suitable. first, the sentinel 1a and 1b satellites provide active remote sensing data with medium spatial resolution and a high temporal frequency. the active data is available under most weather conditions, and is therefore very suited for inland excess water monitoring. second, sentinel 2a and 2b provide multispectral data with a similarly high temporal and spatial resolution. contrary to earlier approaches, in this research, we developed a workflow that is capable of monitoring inland excess water on a weekly basis with sufficiently high resolution. the aim of the workflow is to produce iew maps, that provide information on the location and extent of iew for operational purposes, so operative measures can be initiated to mitigate and prevent further damage. the input data consists of a combination of sentinel 1 radar images and sentinel 2 or landsat 8 multispectral images, complemented with a set of vector files providing a priori information about permanent water and other areas where inland excess water does not occur. all data is independently processed and combined at the end of the workflow to produce an integrated iew map. for each iew maintenance area, the relative coverage by inland excess water is calculated. many scientific publications have focused on causes of iew, like soil characteristics (barta, 2013; gál and farsang, 2013), land use (barta et al., 2016), geomorphology (benyhe and kiss, 2012), or how they interrelate (e.g. kozák, 2006; rakonczai et al., 2011; pásztor et al., 2014). our approach concentrates on the continuous mapping of iew for monitoring purposes and therefore factors related to the development of iew are not taken into consideration. study area and data study area due to its natural characteristics, inland excess water often occurs on the great hungarian plain. because of its low relief intensity combined with intensive or long periods of rainfall, mainly at the end of the winter, water does not run off to larger rivers nor infiltrates at a rate high enough to prevent it from remaining on the surface (rakonczai et al. 2011). the southern region of the great hungarian plain is maintained by the lower-tisza district water directorate and was selected as study area for this research (fig. 1). it has a total area of almost 8200 km2. the region is crossed by the tisza and maros rivers. relief is limited to several meters of height difference and the lowest elevation in hungary can also be found here. based on its soil characteristics, the area can be divided in two parts; the western part has sandy soils, while the eastern part is covered with clay. the west is mildly sensitive to iew according to the palfai iew vulnerability map, while the east is moderately sensitive. several disconnected areas are defined as highly vulnerable (pálfai, 2003). the long-term average size of the area covered by the inundations in the study region is 10 800 ha per year. the largest area covered with iew in recent times was 108 050 hectares in january 2000. the area is mainly agricultural, but there are also villages and some larger cities. the railroad and two highways have considerable influence on the development of inland excess water in the region (barta et al., 2016). each of the used data sets covers the study area with one complete image or tile. the 175th ascending orbit of sentinel 1 completely covers the area. apart from a small strip in the west, the 34tds sentinel 2 tile covers the area, and the landsat 8 wrs 187/28 covers the area except for a small area in the north. in this case study, the focus was to develop a method to generate inundation maps based on the individual images from different sources, therefore only the intersection of the footprints of the three satellite images was used to define the study area for this case study. this circumvents problems with mosaicking data of different acquisition times and sources. fig. 1 the study area on the south part of the great hungarian plain, showing the footprints of sentinel 2 and landsat 8 satellite imagery. sentinel 1 covers the whole study area. towards a continuous inland excess water flood monitoring system based on remote sensing data 11 data sentinel 1 the radar based part of the workflow uses data from the sentinel 1a end sentinel 1b satellites. the two satellites form a constellation that provides an image of the same area of hungary about every third day, using identical instruments. hungary is covered by 4 ascending and 4 descending paths (fig. 2). in the presented workflow, we are using the level-1 ground range detected (grd) product, that consists of focused sar data that has been detected, multi-looked and projected to ground range using an earth ellipsoid model. the phase information is lost. the product has approximately square resolution pixels and square pixel spacing with reduced speckle at the cost of reduced geometric resolution. data was collected in the so-called interferometric wide (iw) swath mode and has a 250 km swath width and a pixel spacing of 10 x 10 meter (malenovský et al., 2012). the data product comes with vv and vh polarization, which are both used in the workflow. different objects in the terrain have different polarisation properties, therefor dual polarization images provide better options for object extraction. sentinel 1 grd iw data was used because it does not require further preprocessing, while it contains enough information to retrieve open water. the acquisition date of the analysed example image is 16 march 2016. fig. 2 sentinel 1 paths covering hungary sentinel 2 the esa copernicus program contains of two multispectral imaging satellites: sentinel 2a and sentinel 2b. at least once every 5 days, they provide highresolution optical data in the visual, near infrared (nir) and shortwave (sw) infrared spectral range for earth observation. level 1c data products are tiled in 100x100 km tiles with 10 km overlap (fig. 3) and store top-ofatmosphere reflectance values with utm projection. hungary is covered by 17 tiles in total. the applied visual and nir bands have 10 meter spatial resolution, while the sw infrared bands have 20 meter spatial resolution. data can be downloaded from copernicus open access hub in safe data package format. a cloud mask comes as metadata layer with every dataset. the study area is covered by the 34tds tile. the acquisition date of the analysed example image is 21 march 2016. fig. 3 sentinel 2 tiles covering hungary landsat the landsat oli multispectral instrument acquires data in 9 spectral band between 0.43–2.4 µm with a temporal interval of 16 days. the 185x185 km images (fig. 4) can be downloaded free of charge within 24 hours after their acquisition. the landsat surface reflectance high level data product “surface reflectance” l8sr data product provides 30 meter atmospherically corrected surface reflectance values for the first 7 spectral bands (usgs 2017). the data product also comes with a cloud mask identifying areas in the image that are not suitable for processing. the acquisition date of the analysed example image is 17 march 2016. fig. 4 landsat 8 wrs paths covering hungary auxiliary data the active and passive remote sensing based workflows require a layer identifying open water. this file is necessary for the determination of the spectral thresholds and as training areas for the classification. open water was extracted from the corine land cover 1:50 000 and 1:100 000 databases and the 20 meter pan-european high resolution layers permanent water bodies maps (copernicus hrl) (büttner et al., 2014) and are stored in a vector layer. the open water file was updated by visually inspecting and editing differences using geoeye imagery from 2014 2015 with a spatial resolution between 0.41 and 1.65 meter available in google earth. in this way, vegetation along the river banks, shadows and infrastructure in the water were removed from the open water layer. 12 van leeuwen et al. (2017) furthermore, urban areas, rural anthropogenic surfaces, paved roads and railroads were extracted from the corine databases and openstreetmap (osm). these objects were stored in a mask layer, identifying areas that were excluded from the inland excess water calculations. the mask layer was further expanded with natural or man-made water bodies and wetlands. the floodplain between levees was also included in the mask. the areas defined as cloud or cloud shadow in the sentinel 2 and landsat 8 cloud masks were not taken into considerations during the iew calculations. methods the method proposed in this research is divided in workflows based on the type of input data. the active satellite data is used in a process where a threshold is defined to separate pixels with water and without water. the passive data sets are processed in two different ways. the first way uses unsupervised classification combined with an automatic method to select the water classes from the classification results. the second way is the calculation of a water index based on the ratios of bands. the following section describes each processing method in detail. downloading satellite data all satellite data used in the workflow can be downloaded without restrictions and without charge. the sentinel 1 and sentinel 2 datasets can be downloaded manually from copernicus open access hub or in an automated way from api hub using opensearch api and opendata api. the downloaded product level is level 1 grd for sentinel 1 and level 1c for sentinel 2 satellites. raw landsat 8 data can be downloaded from the usgs. to acquire landsat surface reflectance data an on-demand request is required. this takes several days and may not always be suitable for operational purposes. preprocessing of satellite data and extraction of water surfaces radar data a disadvantage of radar data is the complex geometric and radiometric processing required to extract useful information from the images. to start the extraction of the waterbodies, the sentinel 1 data first needs to be radiometrically calibrated, a speckle filter needs to be applied to reduce the noise in the image, then the deformations due to the side looking geometry of the sensor and the terrain must be corrected, and finally a correction of the local incidence angle needs to be applied. after these initial steps, the data is geometrically and radiometrically corrected and transformed to a geometry that can be combined with the other data sets. the unit of the processed data is decibel (db). in a geographic information system, the next steps are executed. first, the vector mask indicating the known open water is used to extract the statistics of water from the vv and vh radar images. the two sets of statistics are then used to extract similar pixels in the images, using a threshold method. the threshold method simply extracts pixels below a certain value (the maximum value in the reference statistics), presuming that the radar response of water is considerably lower than the response of other pixels. some correction must be applied due to the statistics of outliers (which remained after the speckle filtering). in the final step of the radar processing workflow, those areas that are known as permanent water bodies or other none iew areas are extracted from the map. the final map is a binary map with two classes: inland excess water inundations and other land cover. optical data the downloaded sentinel 2 and landsat 8 datasets must be preprocessed before the interpretation of surface water patches is possible. the preprocessing workflow for optical data includes atmospheric correction which provides surface reflectance values; resampling of bands with a different pixel size to a common resolution; and spatial and spectral subsetting of the dataset to the study area and to the required spectral bands. to mask unusable areas covered by clouds or their shadow, auxiliary datasets have to be processed. unsupervised classification and class selection on optical data the result of the applied classification algorithm must be evaluated using statistical methods to select the classes representing inundations. for this purpose, reference statistics must be created from training areas permanently or temporally covered by water. from the average of the reflectance values of the training pixels in each spectral band, a reference spectrum can be defined. after getting the reference spectra, the whole preprocessed image is classified. to support operative decisions an unsupervised clustering algorithm was selected to create a classified raster map and a signature file. the latter contains the statistical parameters like minimum, maximum, mean, standard deviation in each band, and covariance matrix of each cluster. in the last step, the spectral similarity between the reference class defined by the training areas and the individual clusters is evaluated. there are many different statistical methods to calculate spectral similarity or spectral separability between cluster of pixels in the nd spectral space. some of them, like for example euclidean distance use only the class mean values to measure n-d distances. advanced calculations, like divergence, transformed divergence and jeffriesmatusita distance (swain and davis, 1978), bhattacharyya distance (b-distance) (jensen, 1986) use the covariance matrix beside the mean vector. in this research, the class similarity to the reference is calculated by the n-d spectral angle difference method, which is not affected by the solar illumination factor and requires only the class means (kruse et al., 1993). the result classes are rated based on this difference: a smaller angle means higher similarity and vice versa. classes with the lowest spectral angle differences represent permanent water or inundations. towards a continuous inland excess water flood monitoring system based on remote sensing data 13 spectral indices in the infrared part of the electromagnetic spectrum, water is absorbed in the swir band, while reflected in the visible range. the modified normalized differential water index (mndwi, xu 2005) uses the green and shortwave infrared bands from sentinel 2 and landsat 8 to extract open water according to the following expression: mndwi = 𝜌𝑔𝑟𝑒𝑒𝑛−𝜌𝑆𝑊𝐼𝑅 𝜌𝑔𝑟𝑒𝑒𝑛+𝜌𝑆𝑊𝐼𝑅 (eq. 1) where ρgreen is band 3 for sentinel 2 and landsat 8 and ρswir is band 11 for sentinel 2 and band 6 for landsat 8 if the water content decreases, the reflectance in swir increases, resulting in a reduced value of the mndwi index. based on the mndwi values calculated from the permanent open water zones in the open water mask, empirically threshold values were defined for the two indicators: mndwi (l8) >= -0,25 and mndwi (s2) >= -0,35 using these thresholds, a binary map was derived with two classes: inland excess water inundations and other land cover. integration the maps that are created based on different input data and using different processing methods need to be integrated to one inland excess water map. for this case study, only images that cover the same area have been used. in the operative situation, this is not realistic since one satellite image does not cover the complete great hungarian plain, and neighbouring images are collected on different dates. this results in a complex situation where output maps from different sources and different acquisition dates will need to be mosaiced. results in 2016, no exceptionally large amount of inland excess water occurred, but from half of february until half of march, some iew developed in the study area. using the described method iew maps were created for this period (week 6 week 11, 6 february 18 march). as an example, figures 5 and 6 show the results for week 11 (13 – 19 march). in this week, all three sources of satellite data, sentinel 1, sentinel 2 and landsat 8 were available. figure 5 shows the results of the active data processing workflow, the unsupervised classification and the index based iew identifications. obviously, every method provides slightly different results. the largest difference is visible in the southeast quadrant where clouds and cloud shadows disturb the unsupervised classification result. when the three workflows are combined, one iew map is created. the different input maps are weighted to define the areas with the highest confidence that iew indeed occurred at the indicated pixels. figure 6 shows only those areas where inundations were identified using all three methods. using data from 3 different sources (sentinel 1, sentinel 2 and landsat 8) and using three different processing techniques (thresholding, unsupervised classification and indexing) results in maximum 5 separate iew maps. if all 5 maps indicate iew for a certain pixel, the change that iew was indeed happening at that pixel is larger than when only one method identified iew at that particular pixel. combining the different maps and counting the amount of positive iew identifications gives an indication for the confidence of iew. fig. 6 the integrated inland excess water map based on three different sources/methods for week 11, 2016. blue indicates water surface fig. 5 sentinel 2 false colour composite (rgb 843) covered with the results of the three separate processing workflows 14 van leeuwen et al. (2017) based on the combined iew maps, thematic maps are created indicating the area and ratio of iew per iew maintenance areas (fig. 7). in operational circumstances, these maps can be used to determine spatial distribution of the severity of iew throughout the region. discussion the presented method consists of three different workflows. each workflow is aimed to create separate inland excess water maps based on procedures that can be used in an operational environment. since the workflow has to be executed within a few days of the acquisition of the data, sometimes the proposed methods are a compromise between speed and accuracy. deliberately, methods are developed that can be automated, so human influence is reduced to a minimum. this also means that there is no possibility for fine tuning of the method to specific situations. this may reduce the accuracy of the method. the threshold method applied to the active data is a relatively simple method, that is easy to automate. in operative circumstances it provides reasonable results, but other techniques might be more suitable when performing detailed iew studies at local scales. the speckle filtering is only based on a single image; therefore, it is not perfect and leaves unwanted spikes in the data which reduce the quality of the extracted statistics. improvements in the speckle filtering should be investigated to improve the method. another promising method is radar based change detection. this method might be useful to identify false positives resulting from the threshold method. inland excess water normally occurs during periods of bad weather and clouds. our method uses multispectral satellite data to complement the active data, but the use of the multispectral data is often hampered due to clouds. using a cloud mask allows us to use those parts of the multispectral data that are not covered by clouds. in the current method, standard cloud masks are used that come with the data products. these masks sometimes do not incorporate all clouds in the images and therefore sometimes lead to misclassifications. improvements of the cloud mask can improve the multispectral data based inundation maps. the result of earlier iew research is often a single map that contains 4 classes: dry land, open water, saturated soil and vegetation in water. the presented workflow ignores the last two categories and therefore probably underestimates the total amount of inland excess water in the region. the determination of the last two categories requires additional data, which changes rapidly in space and time, and this makes it difficult, if not impossible to incorporate them in an automated operative environment, that produces timely, weekly inundation maps for large areas. the intersection of the three data sources was used to determine the study area for this case study. of course, in operational circumstances the complete great hungarian plain needs to be used in the calculations. this increases the complexity of the method. the method could be enhanced using other a priori data sets. the sandy soils show an overestimate of iew inundations. this problem was reduced by applying a different threshold to the radar data, based on the soil type. also, other errors or inconsistencies could be reduced by adding information on e.g. land cover or soil type and by building up a database of landcover dependent threshold values. the proposed method can generate timely iew maps for large areas. independent cross validation of these maps is difficult because they cover large areas and other reliable data is not available. visual inspection of the results using high resolution imagery of small areas indicate that the method identifies inundations at the proper locations. a larger validation campaign based on high resolution aerial photographs of large areas is needed and planned. conclusion earlier approaches to mapping inland excess water were based on field measurements or aerial or satellite remote sensing data for a specific date. we present a method that fig. 7 result maps showing the absolute (in hectare within the area) and relative (as percentage of the area) distribution of inland excess water per maintenance area in the lower-tisza district water directorate region towards a continuous inland excess water flood monitoring system based on remote sensing data 15 is capable of continuously identifying inland excess water over large areas for operative purposes. it shows that combining the most recent active and passive data sources that are available at a very high temporal resolution provide new opportunities and challenges. the presented method provides maps that can be used by the hungarian water directorates to mitigate damage caused by inland excess water, but there are still quite some problems and possibilities for improvements. more scientific research is needed to improve the determination of the threshold for the active data processing workflow and to reduce the number of false positives. also cloud masking of the multispectral data can be improved to better select data suitable for processing. finally, methods for mosaicking the different data from different acquisition dates within the operational workflow need to be developed. esa’s sentinel satellites will continue to provide base data to derive iew maps, which allow for the development of a monitoring database. this database can be used to calculate frequency maps which indicate the vulnerability of an area to inland excess water. acknowledgements this research was funded by the wateratrisk project (husrb/1602/11/0057). references barta, k. 2013. inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain. journal of environmental geography 6 (3-4), 31–37. doi: 10.2478/jengeo2013-0004 barta, k., szatmári, j., posta, a. 2016. connection between inland excess water development and 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(in hungarian). swain, p. h., davis, s.m. 1978. remote sensing: the quantitative approach, mcgraw-hill. szatmári, j., van leeuwen, b. 2013. inland excess water – belvíz – suvišne unutrašnje vode, szeged; újvidék: szegedi tudományegyetem; újvidéki egyetem, p.154. usgs, 2017. landsat 8 surface reflectance code (lasrc) product. ver.4.1. user guide, department of the interior, p.39. van leeuwen, b., mezősi, g., tobak, z., szatmári, j., barta, k., 2012. identification of inland excess water floodings using an artificial neural network. carpathian journal of earth and environmental sciences 7 (4), 173–180. van leeuwen, b., právetz, t., liptay, z.a., tobak, z. 2016. physically based hydrological modelling of inland excess water, carpathian journal of earth and environmental sciences 11 (2), 497–510. xu, h., 2005. a study on information extraction of water body with the modified normalized difference water index (mndwi), international journal of remote sensing 5, 589-595. doi: 10.1080/01431160600589179 introduction study area and data study area data methods downloading satellite data preprocessing of satellite data and extraction of water surfaces unsupervised classification and class selection on optical data spectral indices integration results discussion conclusion acknowledgements references natural hazards in sao vicente (cabo verde) journal of environmental geography journal of environmental geography 11 (1–2), 1–8. doi: 10.2478/jengeo-2018-0001 issn: 2060-467x natural hazards in sao vicente (cabo verde) bruno martins1*, luciano lourenço1, sílvia monteiro2 1department of geography and tourism, centre for studies in geography and spatial planning, university of coimbra, riscos, faculdade de letras, colégio de s. jerónimo, 3004-530 coimbra, portugal. 2department of earth sciences, university of cape verde, praça antónio lereno, cp 379c praia, santiago, cabo verde *corresponding author, e-mail: bruno.martins@uc.pt research article, received 11 november 2017, accepted 6 february 2018 abstract são vicente island (república de cabo verde) lies within the sahelian zone and faces a number of natural hazards, of which the most significant ones are erosion and gully formation, desertification and flash flooding hazards. based on examples, we set out to examine the main factors involved in the development of these natural hazards from a regional point of view, while simultaneously assessing the importance of anthropic action as a structural factor. the investigation of lazareto’s gullies (located to the west of mindelo) aimed to determine the main factors of the gullies formation. it also sought to demonstrate that the gullies’ formation is a reliable indicator of the high rates of erosion on a regional scale. the approach to the desertification hazards was based on farmers’ perception related to the evolution of agricultural production, strategies to mitigate drought and desertification issues, consequences and future prospects based on a set of interviews conducted in ribeira da vinha. finally, the intense rainfall event that occurred on august 26, 2008 was analysed to identify the main vulnerability factors of the city in light of the flash flood hazard. keywords: são vicente (cape verde), risks, vulnerability, flash flooding, gullies formation introduction são vicente faces a number of natural hazards, particularly erosion and gully formation, desertification and flash flooding hazards (pana, 2004). as the archipelago of cabo verde lies within the sahelian zone, it is in a region at high hazard of erosion with serious consequences for the productive capacity of the soil. the steepness of many slopes, the poor vegetation cover, the irregular and concentrated precipitation are the most important factors for explaining how erosive processes are manifested. in rural areas, degradation of the soil is certainly one of the more restrictive phenomena for occupation of the territory and rural development due to the reduction of useful agricultural space (costa, 1996). besides the climate, agricultural-forestry-pastoral over-exploitation also helps to accentuate the erosion hazard. in these conditions, run-off is particularly effective, making use of the slopes with little or no vegetation cover, the absence or thinness of the soil and presence of thick surface formations, creating a relief marked by furrows and gullies. drought and desertification are other serious concerns induced by lifestyles based on agriculture and/or livestock and which may also be linked to urban growth, which generates major environmental and social consequences that are hard to quantify and assess (sepa, 2000a; ferreira et al., 2013). damage caused by drought is generally resolved with short term palliative interventions, even though they need to be repeated periodically over the years. desertification has more severe origins, connected to erosive processes that contribute towards the loss of humidity in the soil, which reduces its availability for vegetation, even in years with more rainfall. the only incontestable proof of desertification for a given area would come from experimental fields, in which all the factors which influence production, except environmental factors, have remained constant for a period of time of never less than a decade, so that it would cover dry years and rainy years (warren and maizels, 1992). although the quantification and strict definition of the areas subject to the process of desertification are difficult to define in cabo verde, numerous areas have suffered severe damage with the natural loss of productivity and environmental recovery processes should be undertaken in são vicente (sepa, 2000a). there are many methods of assessing the soil’s loss of capacity and the levels of desertification and they take different approaches (hare et al., 1992), which are influenced by the concept itself, but which, generally, in more advanced states include gullies. in the initial states the signs are more subtle and easier to correct. therefore, the assessment methods include signs indicating a disturbance in the balance of the ecosystem on the one hand, and, on the other hand, indicators of the levels of severity and recovery (warren and maizels, 1992). on land lacking any protection strategies the rain erosion hazard is high in the sub-humid fringes, due to the greater frequency of concentrated rainfall in the wetter 2 martins et al. (2018) areas. in contrast, wind erosion constitutes the greatest hazard in the drier areas of cabo verde because the surfaces in these more arid areas are poorly compacted. however, very often the processes combine and so in são vicente we frequently find signs of water and wind erosion in different morphoclimatic contexts. stony soil is common in arid spaces and results from the combination of wind and rainwater runoff erosion, leading to the formation of ground surfaces similar to those in deserts. gullies often form on sub-humid slopes and in the areas at the bottom of the slopes, which makes it practically impossible to use them for agriculture. the soils are generally of fine texture with low permeability, with poor infiltration capacity. when precipitation occurs, and because of the low infiltration capacity, the runoff helps to reduce the water that could be made available for vegetation. the way the landscape evolves and the role of erosion in the productive capacity of the soil will therefore largely depend on anthropic action. this should take into consideration the vulnerability of the ecosystems of the dry lands, particularly where vegetation is sparse as it offers practically no protection to the soil against the runoff. in urban areas, rapid construction increases the flash flooding hazard and is one of the most important factors in increasing vulnerability (monteiro, 2007; andrade and silva, 2017). the aim of this investigation was to understand the main factors involved in the development of the erosion hazard and gully formation, together with the dangers of desertification and flash flooding, from a regional point of view. it also set out to assess the importance of vulnerability as a structural factor in the overall dimension of the hazards. the gullies of lazareto, to the west of mindelo, were therefore assessed so as to understand the factors influencing their origination. furthermore, the work showed that gully formation is a reliable indicator of high rates of erosion on a regional scale. the approach to the desertification hazards was based on farmers’ perception related to the evolution of agricultural production, strategies implemented to mitigate the desertification hazard and the consequences of falling productivity on farms in. finally, the episode of intense rainfall that occurred on august 26, 2008 was studied in order to identify the main factors and the vulnerability of the city in the face of the flash flooding hazard. study area located in the atlantic ocean, with latitude situated between parallel 17°12’ and 14°48’ north and longitude which extends from 22°44’ to 25°22’ west of greenwich, the archipelago is composed of ten islands and eight minor islets arrayed in a west-facing horseshoe formation. the islands are traditionally divided into the barlavento (windward) group that includes the islands of santo antão, são vicente, santa luzia, são nicolau, sal, and boa vista, and the sotavento (leeward) group, comprising maio, santiago, fogo, and brava. from a structural point of view, the archipelago is located in a continental interpolate situation (enrst and buchan, 2003), whose genesis would be related to a hotspot mechanism (mantle plumes); a ridged connection of the basement rocks can be seen between the archipelagos of cabo verde and the canary islands fig. 1 são vicente and its location in the archipelago of cape verde. source: adapted from andrade and silva (2017) natural hazards in sao vicente (cabo verde) 3 (patriat and labails, 2006; holm et al., 2008). the cabo verde islands would have originated from the fragmentation of an ancient subcontinental mantle, when forming an oceanic mantle during the opening of the atlantic ocean (o’reilly et al., 2009). the hotspot type activity would have begun around 19 to 22 million years ago and resulted in an uplift crustal area in which the archipelago is implanted (plesner et al., 2002), with volcanic activity still a feature today. the tectonic activity is highlighted with the presence of inter-atlantic transforming rift faults, important lifting processes and a main regional alignment in a nw-se direction, and nnessw tectonic structures (victória, 2013). são vicente has a diversified morphology reaching altitudes of 744 meters in monte verde and 395 meters in monte topona. the city of mindelo is surrounded by slopes that correspond to what remains of the volcano that originated the island and serves as a limit to the city (fig. 1). the archipelago of cabo verde falls within the socalled sahel climatic belt, with an arid and semiarid climate. rain is scant and highly variable. in general, rain falls in the form of showers, at times in heavy downpours that can reach values equal to or above monthly mean values. the rainy season runs from august to october, and can sometimes start in july, associated with the intertropical convergence zone, when this is further north (amaral, 1964; ferreira, 1983). however, the archipelago lies on the fringe of the main convective intensity, which explains the high variability of precipitation over the years. in the dry season, the islands are under an anticyclonic influence, with winds blowing from the northeast – the trade winds. between december and june three types of weather are frequent: (i) “wintering” (december to march); (ii) “dry weather”; and (iii) the “westerly winds” (amaral, 1964). the average monthly temperature varies from 22 ºc in january and february to 27 ºc in august and september. these last two months are also the months where the precipitation values are higher. rainfall events occur with great intensity. the average annual precipitation is 51 mm. according to the thornthwaite climatic classification são vicente has an arid climate. methodology analysis of three different hazards required different methodological approaches. for land cover determination downloaded satellite images from landsat 8 were used with the raster calculator function available in the quantumgis 2.2 valmiera software. two maps (nir and swir composition) with a supervised classification and natural composition using the pan-sharpening methodology were generated. this methodology allowed a higher resolution images which were then used to the definition of the land use areas. gullies located to the west of mindelo were assessed in the field to ascertain the influencing factors. twenty-two samples of soil sediments were randomly collected from the area where the gullies have formed. both surface and depth sampling were used, taking advantage of the gullies’ lateral walls to determine granulometric parameters. the wentworth scale was used for particle size analysis. the fine fraction corresponds to the sum of the elements of less than 0.063mm in size (silt-clay fraction). summing the different fractions we obtained a final weight which, when subtracted from the initial weight, results in the loss by analysis, thus allowing possible errors to be controlled throughout the process. the cumulative curves resulted from the sum obtained for each fraction in relation to the weight sieved, being made up from the thicker elements (2mm). measurements were subsequently taken that describe the granulometry of sediments with central tendency (median mdø, mean mø, graphic mean mz and trend), dispersion (calibration σ), asymmetry (ski) and angularity of the curve (kurtosis). the approach to the desertification hazards was based on farmers’ perception analysis of productivity and strategies to mitigate the potential loss of the soil’s productive capacity. in this order, 12 actions were held for farmers in ribeira da vinha. regarding the observer’s participation, it was a “non-participant observation”, given that we were to remain outside the reality being studied, without interfering or becoming involved in the situation, i.e., it is the community that experienced the situation that will provide us with the information. in terms of the number of observers, it was a team observation, which we have also called “shared”, given that it was conducted by both authors of this paper. it was a “field observation” because it was done at the location of the phenomenon. this classification is also supported in the ideas of lessard hébert et al. (2005) in which the authors refer to “participated observation”. this is because the facts are presented based on the information from the observed subjects, although the latent phenomena have been taken into account by us as observers of the phenomenon. thus, there was a face-to-face relationship in the quest to rebuild the inhabitants’ everyday life. in brief, this research was based on three pillars: direct observation of the phenomenon (interviews with the involved individuals); field survey; own perception based on a combination of the collected information. there were semi-directed individual interviews, given there were some predetermined questions: (i) how farmers perceive the trend in agricultural production; (ii) what measures have been taken to mitigate the problems related to the decline in agricultural production; (iii) the farmers’ future prospects. a logbook was written, recording our perceptions of the events, according to a reference table planned ahead of the trip and the field work. lastly, observation of the manifestation of the flash flooding hazard in the city of mindelo on 26 august 2008 helped to identify the spatial location of the events that occurred and, therefore, to estimate the area, the most susceptible to its occurrence. it also helped us to gain a better understanding of the manifestation of the process and, in this way, to bet ter estimate the consequences in the event of the repetition 4 martins et al. (2018) of similar situations. the rainfall amounts on that day and on the days prior to the event, and also the synoptic descriptions were kindly provided by the national meteorology and geophysics institute of cabo verde. results and discussion erosion hazard and gullies formation the example of the gullies of lazareto (nw of são vicente) periods of intense and concentrated precipitation contribute towards the significant loss of soil and generate powerful torrents due to the steep slopes that are filled with small materials, as a result of the poor vegetation cover (fig. 2), which lend particularly active dynamics to the water courses. it is a common sight in são vicente to see these streams reachi ng the sea loaded with solids, giving the water a yellowish -red tonality, principally near the outflow of the streams (fig. 3). fig. 2 são vicente land use map based on landsat 8 image we can frequently observe gullies that are generally associated with problems of erosion, especially, when they affect areas of cultivation of high economic value. unlike other processes associated to erosion by water like, for example, the rill formation, gullies imply much greater effort of control and erosive correction. in fact, studies developed to mitigate and prevent the effects of erosion attribute severe and often permanent damage to the land due to the action of creating gullies (desta and adugna, 2012). even without affecting areas of cultivation, the gullies in the area of lazareto, in nw são vicente, confirm the importance of erosive processes, as they develop in the area at the foot of the slopes, situated to the east of the edge of the crater that borders the island to the northwest (fig. 4). fig. 3 terminal sector of a stream on laginha beach. note the orange tonality and the materials deposited at the outflow of the stream the deepening and development of the network of gullies essentially depends on the presence of colluvium. in general, colluviums are very heterogeneous varying in size from over a metre to just centimetres with a varied degree of rolling, containing highly rolled blocks and others less so, while the basis is fundamentally formed by coarse sand. they can be more than 3 meters deep, comprising basaltic, conglomeratic material, of pebbles and rocks of black to dark grey in colour that are generally fig. 4 lazareto gullies location. morphological features with land use information based on 2004 aerial photographs with field verification (extracted from martins and rebelo, 2009). 1 – siliceous structural plateau; 2 – siliceous concave slope; 3 – escarpment; 4 – deep groove; 5 – vegetation; 6 – gullies; 7 alluvial ejection cone; 8 – settlement; 9 – road; 10 –deep soils with open scrub. natural hazards in sao vicente (cabo verde) 5 well conserved (w1). the rocks generally have a disorganised disposition, especially the larger ones. occasionally we observe interwoven stratification. the larger rocks are over one meter in diameter, with a great deal of heterogeneity regarding the degree of rolling, some with rounded edges, indicating that they were transported and subsequently deposited. usually occupy a higher position to wind-blown deposit from the stratigraphic point of view (fig. 5). wind-blown deposits correspond to conglomeratic sand dunes from the quaternary period (romariz and serralheiro, 1967; pereira, 2010), fundamentally made up from well calibrated sand which, in some sectors, can be over 30 meters deep. they are quite well stratified. sand predominates (sample trend = 0.5mm) containing bioclasts, mineroclasts and lithoclasts of clear basalt, yellowish to beige in colour. figure 6 shows the curves and graphic illustration of some granulometric descriptive measurements obtained from the mean of the samples collected from the colluvium (fig. 6a) and from the wind-blown sands deposit (fig. 6b). colluvium occupies a higher position generally comprising sandstone and brownish clay/silt deposits, with a basaltic structure. they include sand and small rocks of a basaltic nature, sub-rolled and sub-angular not exceeding 5 cm in diameter. the volume of colluvium, the presence of wind-blown sand and the network of gullies are a reliable indicator of the high rates of erosion on a regional scale. the presence of very deep, recessed gullies, some of which are over 3 meters deep, also suggests a process of densification and recessing associated to each rainy season, confirming the concentrated surface runoff as the main agent of erosion, in particular, in movable materials which, given the absence or scarcity of vegetation together with the weakness of the soil (fine texture and low permeability), has a high intensity of mobilization of detritus. fig. 5 typical profile where we see colluvium and lower down wind-blown deposit. the box of the camera surrounded by the circle serves as a scale the desertification hazard although agriculture occupies only 9,6% of the surface of the country, this activity represents one of the most important sectors of primary production in the archipelago’s socioeconomic development. in the years with the best agricultural results, almost always in line with the quantity and spatial and temporal distribution of the rains, significant changes in macroeconomic fig. 6 granulometric curves and graphic illustration of some descriptive measurements of these curves for the deposits: colluvium (a) and wind-blown (b) (mdø: median, mz: graphic mean, a1: distance between mdø and mz , a2: distance between q1 and mdø, a3: mdø and q3, ski: asymmetry, kg: angularity of the curve (kurtosis)) 6 martins et al. (2018) indicators are recorded, both in inflation and in the purchasing power of consumers, arising from the reduction in market prices (sepa, 2000b and 2000c). on a national level, dry farming is predominant, and is used in over 75% of farms. irrigation farming represents only 17% of farms and agroforestry is below 2%. however, the island of são vicente does not reflect this distribution. the number of dryland farms does not exceed 6%. the farms are mainly irrigated farms and are concentrated around the vinha streams, to the west of mindelo. based on the interviews, irrigation systems that use shallow water wells are at hazard of the salinization hazard, resulting in a drop in production and the consequent abandonment of farms. in these cases, several farmers immediately moved to the urban centres or considered emigrating in the hope of improving their living conditions. however, irrigation using water from the etar (water treatment plant) of vinha had a significant impact on the medium and long term prospects. the use of water from the etar helps to increase the agricultural production of vegetables. currently, more than 40% farms now obtain their water from the etar. poor management of water from the etar and the investment needed to make the irrigation system more efficient are the major concerns mentioned by the farmers. the investments made are high, at times requiring loans, which puts some investors off. the water distribution technique is generally drip irrigation, involving setting out piping to transport the water, which implies enormous investments, both at the outset and a posteriori, in maintenance. this method is used by the majority of the farmers. it consists of releasing water at frequent intervals at strategic points located close to the roots. it also allows the water supply to be adjusted to the soil’s absorption capacity and to the seasonal needs of the crops. all the farmers unanimously reported that, based on this irrigation system, production is more regular and has been increasing. the interviews led to the recognition that the farms affected by desertification are reflected in the decrease in agricultural profitability, as well as in the consequences associated with migration. investigation also shows that abandoning farmland did not resolve the problem of desertification since these problems remain in most farms, especially those which are not investing in irrigation systems. the use of water from the vinha etar was positive as an alternative, although it requires investment, which is a serious obstacle for a good number of the interviewed farmers. the absence of the government is a concern for the farmers interviewed. the flash flooding hazard – the example of that occurred on 26 august 2008, in mindelo the city of mindelo is surrounded by slopes that correspond to what remains of the volcano that originated the island of são vicente and that forms the city limits. rapid urban growth which on average is higher than the growth of the archipelago’s population (fig. 7), has meant that the construction of dwellings and thoroughfares now occupy areas that often correspond to small stream beds that are dry for most of the year, at times for years, but which rapidly fill up when there is more intense and concentrated rain (rebelo, 1999). fig. 7 comparative analysis of the growth of the population in the island of são vicente and in cabo verde, by decade, between 1940 and 2010. data source: ine-cv. this process of urban growth, devoid of planning, is one of the most important factors in the increase in vulnerability to the flash flooding hazard. besides dwellings, many of the avenues and streets are badly affected by flash flooding, as is the case of the rua do côco, which leads to the central hospital of mindelo, baptista de sousa. there are countless examples of clandestine constructions that occupy areas subject both to flash flooding and mud flows. it then becomes very interesting to observe the large channels that cross the city and which, although of varying sizes, were built with the same objective, of leading the rainwater to the sea, but are frequently occupied by dwellings or even truncated by avenues and roundabouts. in the case of mindelo there are therefore factors related with the actions of humans that accelerate and exacerbate the consequences of physical processes. the flash flooding on 26 august 2008 caused enormous material loss. rainfall amounts in the form of showers were over 35mm (fig. 8). this was an episode of rainfall associated with two cells of low pressure, with greater incidence in the region south of cabo verde, which led to the development of convective cloud formation namely cumulonimbus (cb). levels of humidity of over 85% were recorded in the whole of western africa and strong nuclei of vorticity and well defined cyclonic circulation. there was also a tropical wave on the east atlantic (precisely southwest of the archipelago), moving in a northeasterly direction, and the positioning of the intertropical convergence zone (itcz) along an alignment defined by the coordinates 07°n52°w/9°n34°w/16°n25°w and with disperse convection in its central axis (information obtained from the national meteorology and geophysics institute of cabo verde). natural hazards in sao vicente (cabo verde) 7 fig. 8 precipitation distribution (mm), in different intervals, in the weather station of the city of mindelo, on 26 and 27 august 2008. data source: inmg-cv although the precipitation resulting from this meteorological situation may have been a major factor in triggering the whole process, it cannot be the only explanation for what happened. in fact, slopes and soils with poor infiltration capacity, together with the morphological characteristics of the city and, above all, the significant increase in the constructed surface area which, in turn, increases the impermeable area, mean that more water remains on the surface and increases the speed of the river water, namely when full, thereby making the runoff process more violent. from the point of view of preventing this hazard, measures have to be taken that delay the runoff’s response to intense rain, increasing the time of concentration and, therefore, reducing the velocity of the surface runoff. however, the disorganised growth of the city contributed towards the destruction of important drainage channels, built with the intention of channelling the surface waters and also increasing the drainage speed, so it would reach the sea more quickly. therefore, although the process or physical phenomenon has remained practically unchanged an inadequate response strategy significantly increases the hazard consequences. in order to mitigate the effects of flash flooding hazard, in december 2010, the town hall of são vicente carried out some torrential correction works, one of the main ones being the construction of dikes in the upper reaches of the water courses and drainage channels in the rua do côco and near praça estrela (fig. 9). while these works are considered to be effective in hazard mitigation, rainfall crises continue to occur in various areas of the city of mindelo, as was the case of the flash flooding in september 2013 (fig. 10). the losses were only material, but they showed that the drainage system is still insufficient. on the other hand, for the same intensity of rain we see that the flash flooding hazards have unfortunately increased. fig. 9 torrential correction works near praça estrela in december 2010 fig. 10 the flooding of the rua do côco in september 2013 conclusion as the archipelago of cabo verde is inside the sahelian zone, it is in a space of high erosion hazard with serious consequences for the productive capacity of the soil. periods of intense and concentrated precipitation play a part in significant loss of soil and generate powerful torrents as a result of the poor vegetation cover. the network of lazaretto gullies is a reliable indicator of the high rates of erosion on a regional sca le. the presence of very deep, recessed gullies, some of which are over 3 meters deep, also suggests a process of densification and recessing associated with each rainy season, confirming concentrated surface runoff as the main erosion agent, particularly with respect to movable materials. the interviews led to a recognition that the farms affected by desertification are reflected in both the fall in agricultural profitability and the consequences associated with migration. our research also shows that the abandonment of agricultural fields did not solve the problem of desertification since most farms still suffer this problem, especially those which are not investing in irrigation systems. the use of the water from the vinha 8 martins et al. (2018) etar was positive as an alternative, although it requires investment, and this is a serious obstacle for many of the farmers we interviewed. most farmers feel there is too little government support. disorganized urban growth is responsible for the increased flash flooding hazard through the destruction of important drainage channels that were built with the intention of channelling the surface waters and also increasing drainage speed, so the flow would reach the sea more quickly. in climatic zones subject to intense erosive processes and where the ecosystems’ response to anthropic interventions is very sensitive, as is the case of the island of são vicente, action in the territory should be cautious. in fact, the growing abandonment of agricultural-pastoral activities will not resolve the problems, quite to the contrary, as the abandonment of agricultural areas and the consequent rural exodus may increase the vulnerability of the urban areas, in particular, in the larger cities, as is the case of the city of mindelo. acknowledgements the daily rainfall amounts for 26, 27 and 28 august 2008 and the synoptic surface situation for 26 august 2008 were kindly provided by the national meteorology and geophysics institute of cabo verde, to whom we express our gratitude. references amaral, i. 1964. santiago de cabo verde. a terra e os homens. lisboa, junta de investigações do ultramar, 444 p. andrade, d, silva, j. 2017. contributos para uma estrutura de ordenamento da cidade-ilha de mindelo-s. vicente (contributions to a spatial planning structure of the city-island of mindelo-s. vicente) revista de geografia e ordenamento do território (got) 11, 7–31. doi: 10.17127/got/2017.11.001 costa, f. 1996. processos erosivos actuais na bacia da ribeira seca (santiago oriental – cabo verde), garcia da orta. série de geografia 15 (1), 29–34. desta, l., adugna, b. 2012. a field guide on gully prevention and control, nile basin initiative eastern nile subsidiary action program (ensap), addis ababa, ethiopia, 67 p. ernst, r. e., buchan, k. l. 2003. recognizing mantle plumes in the geological record. annu. rev. earth planet. sci. 31, 469–523. doi: 10.1146/annurev.earth.31.100901.145500 ferreira, a. baptista, i., tavaes, j. 2013. a luta contra a desertificação em cabo verde. in riscos naturais, antrópicos e mistos, book in tribute to professor fernando rebelo, coimbra, 697–712. ferreira, d. 1983. étude de la convection au-dessus de l’atlantique tropical au large de l‘afrique occidental. course of physical geography action, report no. 16, lisbon, ceg, inic, 37 p. hare, f. k., warren, a., maizels, j., kates, r. w., johnson, d. l., haring, k. j., garduño, m. 2012. desertificação: causas e consequências, calouste gulbenkian foundation, lisbon, 677 p. holm, p., grandvuinet, t., friis, j., wilson, j., barker, a., plesner, s. 2008. an 40ar-39ar study of the cape verde hot spot: temporal evolution in a semistationary plate environment. journal of geo physical research: solid earth 113, b8. doi: 10.1029/2007jb005339. ine-cv national statistics institute of cape verde lessard-hébert, m., goyette, g., boutin, g. 2005. investigação qualitativa. fundamentos e práticas. instituto piaget, coleção epistemologia e sociedade, lisboa, 184 p. isbn: 9789896591021 martins, b., rebelo, f. 2009. desertificação, erosão e paisagem em são vicente e santo antão (cabo verde). territorium: revista portuguesa de riscos, prevenção e segurança 16, 71–80. doi: 10.14195/1647-7723_16_7 monteiro, s. 2007. riscos naturais e vulnerabilidades no concelho de ribeira grande – ilha de santo antão – cabo verde. master's dissertation, coimbra. o’reilly, s.y., zhang, m., griffin, w.l., begg, g., hronsky, j. 2009. ultradeep continental roots and their oceanic remnants: a solution to the geochemical “mantle reservoir” problem?, lithos 112, 1043−1054. doi: 10.1016/j.lithos.2009.04.028 pana, 2004. segundo plano de acção nacional para o ambiente 20042014, ministry of agriculture, food and the environment, praia (republic of cape verde) 218 p. patriat, l., labails, c. 2006. linking the canary and cape-verde hotspots, northwest africa. marine geophysical researches 27 (3), 201−215. doi: 10.1007/s11001-006-9000-7 pereira, j. 2010. concepção de uma estratégia de geoconservação para cabo verde e sua aplicação à ilha de santiago. phd thesis. minho university, 383 p. plesner, s., holm, p., wilson, j. 2002. 40ar–39ar geochronology of santo antão, cape verde islands. journal of volcanology and geothermal research 120, 103−21. doi: 10.1016/s03770273(02)00367-0 rebelo, f. 1999. riscos de inundação rápida em cabo verde. apontamentos de observação numa breve visita à praia e ao mindelo. finisterra 34 (67-68), 47−55. available at: http://revistas.rcaap.pt/finisterra/article/view/1684/1378 romariz, c., serralheiro, a. 1967. litofácies do arquipélago de cabo verde 1. ilha de são vicente. garcia da orta 15 (4), 535−544. sepa executive secretariat for the environment 2000a. national action plan to combat desertification (pan-lcd). ministry of agriculture, food and the environment, praia (republic of cape verde). sepa executive secretariat for the environment 2000b. white paper on the state of the environment in cape verde. ministry of agriculture, food and the environment, praia (republic of cape verde). sepa executive secretariat for the environment 2000c. planning and organisation of the natural resources of the republic of cape verde. cabo verde natura 2000. ministry of agriculture, food and the environment, praia (republic of cape verde). victória, s. 2013 caracterização geológica e geotécnica das unidades litológicas da cidade da praia (santiago, cabo verde) (geological and geotechnical characterization of lithological units in the city of praia (santiago, cape verde)). doctoral thesis, university of coimbra, portugal. warren, a., maizels, j. 1992. mudança ecológica e desertificação. in desertificação: causas e consequências, lisbon, calouste gulbenkian foundation, 265−407. https://doi.org/10.1007/s11001-006-9000-7 introduction study area methodology results and discussion erosion hazard and gullies formation the example of the gullies of lazareto (nw of são vicente) the desertification hazard the flash flooding hazard – the example of that occurred on 26 august 2008, in mindelo conclusion acknowledgements references evaluation of potential reservoir deficiency due to climate change journal of environmental geography 12 (1–2), 33–40. doi: 10.2478/jengeo-2019-0004 issn 2060-467x evaluation of potential reservoir deficiency due to climate change, kesem kebena dam, ethiopia melese chanie shumie* civil engineering department, college of engineering, debre berhan university, block 24-558 tebase, kebele 09, st. gabriel church, 445 debre berhan, ethiopia *corresponding author, e-mail: kelem.meles@gmail.com research article, received 4 january 2019, accepted 26 march 2019 abstract flood is an excess inundation of water on a surface and difficult to manage. the flood occurred in previous decades of afar region of ethiopia, consequently, leads to the death of human beings, destruction of infrastructures, an annihilation of massive hydraulic structures, and downstream properties. the main responsible factors for the flood incidences of the region are climate change, global warming, deforestation, and desertification. climate change, however, is the foremost reason of increasing flood hazard. to coincide with this, hydraulic structures are designed based on the previously recorded flow data of a river. in ethiopia, numerous earthen dams are constructed. the water storage capacity of dams is determined by the appraised flood of the upstream catchment: however, when the catchment flood increases due to climate extremes, the constructed structures cannot carry and going to demolish. the extra water that rises due to climate change from the catchment has to be removed before joins to the reservoir. this study has evaluated the potential reservoir deficiency of kesem kebena dam due to climate change. the study has comprehended different methods based on scientific criteria and selects the appropriate measure. as per the research output, the excess water that will arise from the catchment and add to the reservoir can be controlled by diversion floodways (emergency spillways). the study has determined the amount of excess flood join to the reservoir for the excess rainfall incident month (august) for 100 years return period. its magnitude is 85.76m3/s. the emergency spillway is the best means to divert such unwanted water before joining to the reservoir. its hydraulic design is discussed in the study. keywords: climate change, kesem kebena dam, reservoir, prioritization, emergency spillway introduction a flood is an overflow of a large volume of water on normally dry land beyond its normal limits (salas et al., 2014). it is a natural phenomenon and nobody can preclude (shaw, 2005). the floods on a catchment join to streams, channels, and rivers. the flow of these courses are recorded and documented for a certain year (chow et al., 1988). then, the documented and forecasted flood data are expedient to design hydraulic structure constructs on a river. climate change, an uncertainty of flood estimation methods, global warming, deforestation, desertification, data constraint, and soil degradation are the main features for the incident of an excess flood (onwuka and ikekpeazu, 2015). as it is well known, the foremost governing factors used for hydraulic structure design are a maximum flood, project cost, and susceptibility to flooding, intended purpose and location (botto et al., 2014). the above-mentioned features have prominent influence and shall be considered while designing water structures. most of the riverine constructions in ethiopia are planned and built by starved of bearing in mind of these features (asfaw et al., 2014). hydraulic structures like earthen dams are susceptible to overtopping (garg, 2006). as soon as the reservoir is entirely full it cannot tolerate tallying of extra and unwanted water to the reservoir. this surplus water is going to over top the dam. the extra water endangers the structure and the hydraulic stability of the dam. a dam intends to be stable during construction, end of construction and in its service years (arora, 2012). suitable and appropriate measurements and solutions shall be considered in advance before a superfluous flood develops and makes problems. ethiopia is one of the largest developing countries in east africa. its topographical characteristics have made the country pretty vulnerable to floods (abaya, 2008). the flood occurrence in different regions of the country leads to destruction of infrastructures system and damage to life. as per the abaya’s 2008 climate change study report, climate change is the major development challenge of the country. it has a significant impact on the incident of excess water (abaya, 2008). for several years, floods have occurred in different areas of the country. 2007 in dire dawa and south omo, 2014 in kemisse and 2017 in meteka were the dangerous flood incidents which caused the deaths of dozens of people (haile et al., 2013). in particular, the meteka flood was the near year event and affected the displacement of more than 3,000 people from their home. the incident was captured as a photo as shown in fig. 1 a) and b). it is located downstream of the study area. enormous water construction projects have been completed in different areas of the country (wwdse, 2006). most of them are multi-purpose dams and are 34 shumie 2019 / journal of environmental geography 12 (1–2), 33–40. vulnerable to flooding. among these, kesem kebena dam project was designed to supply irrigation water for a 20,000 ha land. in 2008 the kesem kebena dam upstream catchment flood hazard demolished a 35m high dam at kesem river. the total cost of the dam was two million us dollars by the time. fig. 1 a) flash flood devastating meteka town of afar region of ethiopia in july 2017, b) the communities were displaced from their village effect of climate change for flood intensification at the research area was not scientifically studied before: however, scholars have investigated and quantified climate change influence on other similar catchments. as stated by wobus, et al., it has a significant effect to make an excess flooding. climate change consequences a rise of 25% flood magnitude for 10 and less years return periods. it also makes 50% rise for 15-30 years return period and 67% flood magnitude increments for 100 years return periods (wobus et al., 2017). climate change is, even, worthy on the augmentation of floods for longer return periods. structures built across rivers are especially vulnerable to floods (ranghunath, 2006). potential damage can be decreased by structural and non-structural, hydraulic measures (suykens et al., 2016). fundamental structural hydraulic measures are: confining flood banks, river bed character improvement, flood diversion through floodways, reservoir storage improvement and cascade dams (hudson and harding, 2004). whereas, the non-structural hydraulic measures include performing land use practice and soil conservation on flood plains, proclaim dam safety guidelines, adaptation of a flood warning system, community educations and geophysical information system (hudson and harding, 2004). these two itemized methods and their lists are aid to control both expected and excessive floods. it is unlikely to use all of these measures for a specific site. therefore, the prioritization of measures and scientific studies are very vital. there are many hydraulic flood controlling methods. all of them are not necessarily significant for a specific site. prioritization of measures for a dam site is very important. the question of when and where the measures appropriateness is answered by observing and assessing previously studied substantial scientific papers. the study discusses intended hydraulic measures and set its ultimate solution. measures are appraised and discussed based on precise criteria. the criteria are implementation cost, construction simplicity, appropriateness to control flooding, durability, efficiency, and the place where the measures are located with reference to the structure (stephens, 2012). the detail table 1 structural flood controlling methods evaluation and selection measures advantages disadvantages economic issues confining the flow between high banks important for protecting an area from over bank floods it doesn’t intend to decrease the due surplus water joins to the reservoir costly river bed character improvement retard channel flood during its tide. it signifies flood by reducing its speed and increasing its storage volume changes the existing ecosystem and ecology of the river. it is not critically important to protect a downstream structure from excess water. less significant diversion floodways important to preserve the dam from overtopping and demolishing needs appropriate saddle point to be effective moderate improve reservoir storage capacity it helps during dam construction its use is inhibited for full reservoir condition. costly cascade dams the measure constructs at the upstream side of the flood prone area. constructing a dam for protecting other dam from flood hazard alone is illogical. costly adopting soil conservation when the upstream catchment is conserved, the amount of flood becomes retarded. the upstream catchment of the study area is not ominously important and not significant to soil conservation. less significant shumie 2019 / journal of environmental geography 12 (1–2), 33–40. 35 measures appraisal and selection is done based on the listed out parameters of table 1. the evaluation is done qualitatively for each measure’s advantage, disadvantage and economic issues. from the mentioned measures in table 1; diversion of a flood through floodways, channel character improvement and soil conservation did not need more construction times, resources and crews. the remaining measures, i.e. confining the flow between high banks, providing a temporary storage reservoir, and improve the storage characteristics of the dam reservoir; however, needs large crews, resources and times. if the intention is to reduce certain percentage of flood these laterally mentioned methods are not significantly important. the prioritized flood controlling measures at the dam reservoir is the first mentioned methods. but, the last two are not significantly important, i.e. river bed character improvement and soil conservation. terrace and planting of trees conservation measure were there at the reservoir upstream catchment but the flood occurred and demolished the 35m high dam. from this, it is understood that even if the measure is already exercised, it was not critically significant. river bed character improvement has little significant and it has a negative impact in changing the ecosystem and ecology of the river. as per the above explanations, all measures have specific aptness and snags. therefore, thinking ahead about climate changes and propose diversion floodways is very important. eventually, diversions of a portion of flood through floodways are the best prioritized flood controlling measures to protect earthen dams from excess flood (cowin and bardini, 2011). this study evaluated the potential deficiency of the reservoir of kesem kebena dam due to climate change and designed appropriate structural hydraulic measures for controlling surplus flood water. in general, the research targeted to protect constructed earthen dams from excessive and unconsidered flood hazard throughout its service years. study area the study focused on the kesem kebena dam site (fig. 2). the site is located in kesem catchment (fig. 2 c)), which is a sub-catchment of awash basin (fig. 2 a)) and b)) and located between altitudes of almost 3,471m to 870m above sea level (fig. 2 b)). its latitudinal and longitudinal directions are within 9005'18''n 39008'26''e to 9008'56''n 39053'03''e. the upstream catchment to dam site covers about 3,135km2 (fig. 2 c)). the length of the river up to dam axis is 230km (fig. 2 c)). the dam site experiences a typically tropical semiarid climate with rainfall range of 350mm to 600mm per annum. temperature varies from mean minima of 15ºc and 21ºc to mean maxima of 23ºc and 38ºc in december and june respectively. mean relative humidity is lowest in january, 36% and highest in august 58%. mean daily sunshine reported on an annual basis is 8.5hours. the catchment experiences from cold to hot weather conditions at its lowland and highland areas respectively. its rain range falls between 350mm in lowland arid areas to 1,500mm per annum at highlands. the land use condition of the catchment mainly includes: cultivated agricultural land, bare land, grassland, forest land, and rural and urban settlements. the lad use condition of the catchment percentage is shown in figure 3. the most common soil types are 12% lithosols, 20% cambisols and 68% gypsisols (paulose, 1989). fig. 2 a) ethiopia river basins, b) awash basin, c) kesem sub-catchment fig.3 land use condition of the catchment data and methods meteorological data collection in this study 14 meteorological stations located in and around kesem catchment were considered. the data of sheno, shola gebeya, balchi, chefa donsa and alaltu were studied more intensively as they fell within the catchment upstream of the reservoir. thus, except july, august and september, as shown in table 2, rainfall is highly variable. these dates are the 36 shumie 2019 / journal of environmental geography 12 (1–2), 33–40. last 52 years monthly average rainfalls, shown in table 2, (1966 to 2017) and higher than the 34 years monthly average data that the dam was initially designed, shown in table 3, (1966 to 1999). it indicated and proved that there is a rainfall increment and the difference in percentage is expressed in table 4. reservoir and spillway the dam is zoned and constructed from earthen materials. its structural height is 43m. the approximate reservoir capacity at its full supply level is 500 million m3 (wwdse, 2006). its fetch distance is 8,000m (wwdse, 2006). the site has a concrete spillway, to spill the excess water from the reservoir, separated from the body of the dam. it is located at the right side of the dam reservoir. it has 1.5m effective discharge head (wwdse, 2006). the water discharges from the reservoir to the downstream command area is by 5m diameter tunnel. it is the water outlet for both downstream ecosystem and irrigation area. hence, the average outflow from the dam pass through the tunnel is 11.74m3/s (wwdse, 2006). maximum monthly rainfall for this study a 52-years monthly average rainfall data was taken from ethiopian metrological agency nearby stations and used to estimate the maximum extreme rainfall magnitude. to make the research reliable, 100 years return period is considered. the gumbel’s method of extreme hydrologic event (chow et al., 1988) is considered for maximum monthly rainfall scenarios. the method applicable to extreme hydrologic event is expressed as: xt = u +a yt (eq.1) u = x0.5772*a (eq.2) a = 0.7797*s (eq.3) yt = -ln(ln(t/(t-1))) (eq.4) where u = mode of distribution; yt = reduced variate; x = mean of the samples (table 3); s = standard deviation, kt = frequency factors, t = return period, xt = maximum rainfall magnitude for t years return period then the estimated maximum rainfall magnitude is probably happened in august because it is the maximum rainfall month as the climatological data shows. the remaining months maximum rainfall data were taken by taking the rainfall incremental percentage between the maximum monthly data from table 2 and the computed maximum rainfall magnitude of august. peak inflow discharge the rational method is used to estimate the peak runoff volume of the catchment. it is the inflow volume of the reservoir. the rainfall volume (in a million cubic meters), was computed using the following equation: v = 1,000*cia (eq.5) where; the rainfall volume (v) is expressed in a million m3, c is the average runoff coefficient, i = xt is the computed maximum monthly rainfall of 100 years return period in mm, and a is the catchment area in km2 (3,135). the extreme rainfall magnitude is the rainfall record that will happen in a month. it is difficult and uncertain at what time and day it will happen within the month. so the appropriate and best scenario is keeping this maximum rainfall magnitude for the determination of monthly inflow discharge. that is why the research was conducted by assuming the rainfall magnitude at the maximum level throughout the month. the maximum inflow will happen at august as the rainfall trends indicated in table 2 and 3. the average runoff coefficient of the catchment has been taken from the topographic nature of the runoff surface (0.497). the land use and land cover of the catchment helps to know its runoff coefficient. the catchment has different types of land covers. then, its average runoff coefficient is estimated by taking the weighted average of more than 30 small watershed land use of the upstream catchment with their corresponding runoff coefficient and area cover. c = ∑ (ci*ai) (a1+a2+…+an ) n i=1 (eq. 6) table 2 monthly average rainfall data of the 14 rain gauge stations in the period of 1966-2017 (source: ethiopia metrological agency) month jan feb mar apr may jun jul aug sept oct nov dec rf (mm) 12.1 28.2 47.2 5.7 45.8 63.1 242.5 261.4 99.3 25.1 9.9 5.7 table 3 monthly average rainfall data of the 14 rain gauge stations in the period of 1966-1999) (source: ethiopia metrological agency) month jan feb mar apr may jun jul aug sept oct nov dec rf (mm) 10.8 26.7 47 5.6 43.1 60 221.5 230.9 94.6 24.7 10 5.7 table 4 monthly average rainfall data increment of the 14 rain gauge stations between the two investigated periods (1966-1999, 1966-2017) (source: ethiopia metrological agency) month jan feb mar apr may jun jul aug sept oct nov dec rf increment (%) 12% 6% 0% 2% 6% 5% 9% 13% 5% 2% 0% 0% shumie 2019 / journal of environmental geography 12 (1–2), 33–40. 37 monthly outflow volume the outflow volume of the dam arises from its bottom outlet and/or main spillway. the spillway has effective length and height. its maximum discharge is estimated by considering the full effective length, height and velocity (wwdse, 2006). they are secondary data obtained from the hydrologic design report of the kesem kebena dam. the bottom outlet is also considered constant and taking the full flow through the 5m diameter tunnel. the research is done by taking the secondary data from hydrologic design report of kesem kebena dam report (wwdse, 2006). monthly excess water volume the monthly excess water joined to the reservoir is computed by considering the outflow from both the spillway and the bottom outlet (tunnel), inflow from the catchment and storage from the reservoir. the computation is made for each month starting from august. the calculation is assumed that the dam is full at the end of july before the start of the computation i.e. august. as the previous experience shows most of the ethiopian earthen dams have been fully filled at the end of july. so it is better to start the simulation by assuming the dam is initially full. vm=i+s-o (eq.7) where: vm: monthly excess water volume, i: inflow, s: storage, o= outflow the spillway outflow volume is considered when the difference of monthly inflow and storage of the dam is greater than the total capacity of the reservoir and its bottom outlet. the maximum effective storage volume of the reservoir is 500 million cubic meters (secondary data from wwdse) and its spillway design discharge is equal to 106.61m3/s (secondary data from wwsde). the computation is made for 100 years return period because the other lower years discharge cannot exceed the discharge due to 100 years return period. emergency spillway design these are spillways which provided for additional safeties of the dam, which not contemplated by normal design assumptions. the research site (dam) is already completed and providing its service. so, the researcher couldn’t modify the main spillway design. then, the proposing solution is diverting the excess water at the entrance of the reservoir using emergency spillway. its crest is set at the maximum design water level of the dam. its main purpose is to protect the dam against overtopping due to extreme flood conditions. spillway design computations the height of the spillway above the ground level is the total height from the normal spillway level to its crest (2m). the surplus water volume is computed from the inflow, outflow, and storage simulation. the design discharge of the emergency spillway is computed using equation (8) and its effective length is computed by the equation (9). q = c*le*he3/2 (eq.8) where: q is discharge in m3/s, c is the coefficient of discharge (1.8), le is the effective length of the crest of the spillway (m), he is the actual effective head including the head due to the velocity of approach le = l 2*(n*kp + ka)*he (eq.9) where: le is crest effective length, l is net length of crest which is equal to the sum of the clear spans of the gate bays between piers, he is a total head on crest, including velocity head, n is number of piers, kp (0.01) is a pier contraction coefficient and ka (0.1) is an abutment contraction coefficient (arora, 2012). ogee crest design the shape of an ogee spillway depends upon a number of factors such as head over the crest, height of the spillway above the bed of the entrance channel and the inclination of the u/s face of the spillway (garg, 2006). several standard ogee shapes have been developed by a united states army corps of engineers and the vertical shaped ogee is most familiar and has the following set out (fig. 4). fig. 4 ogee spillway cross sectional profile the downstream profile is drawn by the equation, xn = khd n-1y. where: x and y are the coordinates of the points on the crest profile with the origin at the highest point called the apex, hd: design head excluding the head due to velocity of approach and k & n are constants which depend on the inclination of the upstream face whereas the upstream profile is drawn by using the parameters a, b, r1 and r2. the spillway is uncontrolled at its crest. results and discussion maximum monthly rainfall according to equation 1 to 4 and table 2, u = 30.65; a = 69.5, yt = 4.6. then xt = 350.35mm, it is the maximum monthly rainfall magnitude as per gumbel’s method of extreme event distribution and will happen in august. the percentage increment of the 52 years average rainfall and the newly computed extreme event magnitude of august is 34.02%. this increment will help to arbitrarily fix the other months increment for inflow-outflow tabulation. computing excess flood volume to obtain the monthly excess flood magnitudes, the monthly average rainfall data of 14 rain gauges were taken. as the result of the study shown in table 5 and 6, 38 shumie 2019 / journal of environmental geography 12 (1–2), 33–40. the dam cannot tolerate to carry the whole volume of water added to the reservoir in july and august. there is extra water in these months joins to the reservoir. the surprising thing, here, is that the dam, even, could not carry the volume of water in july and august produced by the current rain fall magnitudes (table 5). it is a shock situation. the dam was in danger at the end of july 2018 due to the symptom of overtopping since the dam was extremely full. the government decided and diverted a portion of water at the upstream side of the dam and it made the dam stable. the result of the study is an approval of that situation. the situation is even grave when the 100 years return period extreme climate change conditions are considered. the surplus water for this return period is much extreme and immediate action is needed to control the condition. as it is shown from table 5 and 6, unwanted extra water is added to the reservoir in july and august. the designed emergency spillway benefits to remove this extra water from the reservoir. plus, the spillway is designed by using the maximum surplus water originated in august. the study was conducted by assuming, this extra flood discharge will occur in certain days within the month. it is difficult to know the exact days of the month and the study has been conducted considering the maximum discharge throughout the month. the maximum surplus design discharge (water volume) which is obtained by taking the current rainfall magnitude is 34.03m3/s (91.15*106 m3/ month). in the same procedure, the 100 years return period maximum surplus design discharge is 85.76m3/s (229.70*106 m3/month) respectively. the computation is a yearly based simulation. ogee profile and hydraulic design the provided extra spillway is vertical upstream face and ogee shaped. its initial effective length was 18m. the maximum 100 years return period design discharge of the spillway is 85.76m3/s. the central pier which equally divides the spillway and carries the bridge is 1m thick and square in cross section. the adjusted coefficient of discharge of the spillway is 2.15. the coefficient is adjusted with effect of approach depth, head ratio, upstream face slope and downstream apron interference. the spillway effective length and the head is computed using equation 1 and 2. hence, its effective length (le) considering abutment and pier contraction effect is 16.6m and the effective head including the velocity head, he, is 1.76m. the velocity head of the spillway is 0.08m and small. so, hd is 1.68m. the supposed spillway is vertical upstream face and n = 1.85 and k = 2.00. x1.85 = 2hd 0.85y and hd is 1.68m, then, x1.85 = 3.11y. the maximum value of y is equal table 5 the monthly inflow, outflow, storage and surplus water volume in million cubic meters for current rainfall magnitudes month rf (mm) inflow available storage dam outlet main spillway temporary total available water* spill out water net available water** surplus aug 261.40 407.29 500.00 31.54 284.60 875.75 284.60 591.15 91.15 sep 99.30 154.72 500.00 30.52 275.42 624.20 124.20 500.00 oct 25.10 39.11 500.00 31.54 284.60 507.57 7.57 500.00 nov 9.90 15.43 500.00 30.52 275.42 484.91 484.91 dec 5.70 8.88 484.91 31.54 284.60 462.25 462.25 jan 12.10 18.85 462.25 31.54 284.60 449.56 449.56 feb 28.20 43.94 449.56 28.49 257.06 465.01 465.01 mar 47.20 73.54 465.01 31.54 284.60 507.01 7.01 500.00 apr 5.70 8.88 500.00 30.52 275.42 478.36 478.36 may 45.80 71.36 478.36 31.54 284.60 518.18 18.18 500.00 jun 63.10 98.32 500.00 30.52 275.42 567.80 67.80 500.00 jul 242.50 377.84 500.00 31.54 284.60 846.30 284.60 561.70 61.70 *inflow+available storage–dam outlet; **temporary total available water of the dam–spill out water table 6 the maximum monthly inflow, outflow, storage and surplus water volume in million cubic meters of 100 years return period rain fall incidents month rf (mm) inflow available storage dam outlet main spillway temporary total available water* spill out water net available water** surplus aug 350.33 545.84 500.00 31.54 284.60 1,014.30 284.60 729.70 229.70 sep 133.08 207.35 500.00 30.52 275.42 676.83 176.83 500.00 oct 33.64 52.41 500.00 31.54 284.60 520.87 20.87 500.00 nov 13.27 20.67 500.00 30.52 275.42 490.15 490.15 dec 7.64 11.90 490.15 31.54 284.60 470.52 470.52 jan 16.22 25.27 470.52 31.54 284.60 464.24 464.24 feb 37.79 58.89 464.24 28.49 257.06 494.64 494.64 mar 63.26 98.56 494.64 31.54 284.60 561.66 61.66 500.00 apr 7.64 11.90 500.00 30.52 275.42 481.38 481.38 may 61.38 95.64 481.38 31.54 284.60 545.48 45.48 500.00 jun 84.57 131.76 500.00 30.52 275.42 601.24 101.24 500.00 jul 325.00 506.38 500.00 31.54 284.60 974.84 284.60 690.24 190.24 *inflow+available storage–dam outlet; **temporary total available water of the dam–spill out water shumie 2019 / journal of environmental geography 12 (1–2), 33–40. 39 to the spillway height (2m). the necessary values of x and y for drawing the spill way cross-sections are tabulated in table 7. the upstream ogee profile parameters: a is equal to 0.29m, b is equal to 0.47m, r1 is equal to 0.84m and r2 is equal to 0.34m. the crosssectional profile of the emergency spill way is shown in fig. 5. table 7 the downstream ogee profile design (m) y 0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 x 0 0.87 1.27 1.58 1.85 2.08 2.30 2.50 2.69 conclusion climate changes are aggravated conditions for excess flood incidence in a catchment. their impact studies by different researchers and shivering in flood increment for longer return periods. hence, the study has shown its discharge augmentation amount. the flood that occurred at kesem catchment in 2008 was a flash flood. the catchment is very susceptible to flooding and in danger for the stability of the dam. it is impossible to prevent such floods whereas the flood can reduce their effect by providing control structures. the design flood of a hydraulic structure constructs in a river can be estimated by analysis of stream flow data and/or rainfall based methods. but, there is no stream flow measuring devices at the river of the research site. so, the rainfall based flow estimation is the concurrent and the only means to estimate the river design flood. the average rational method provides an appropriate and reliable result for such scenarios from the rainfall based analysis methods since the others provide either exaggerated or less result. the assessment of inflow-storage-outflow volume simulation by considering the current and future climate change impact is very important to know the situation of the reservoir. according to this, the study shows that the reservoir cannot tolerate the surplus water for the coming 100 years. therefore, the foremost thing that shall be done at the site level is implementing the prioritized flood control structure immediately. all excess flood controlling structures are not necessarily important for a specific site. then, it has to be scientifically priorities to select the best measure for a specific site. from numerous flood controlling structures, flood diversion through floodways is the best-prioritized flood control structures in the study area. thus, the researcher selected emergency spillway for immediate action and the safety of the dam. the emergency spillway has helped to remove excess water from the reservoir and safely save the dam from a hazard. the spillway is designed based on surplus water from the inflow-storage-outflow simulation of the reservoir. however, the study did not include its geotechnical and structural design. the proposed structural flood controlling measure for kesem kebena dam is the best solution for the current risky flood conditions of the reservoir site. it is crucial to protect structures especially the main dam, which is mostly constructed from earthen materials, from the superfluous water. then, the measure will protect it from an excessive flood. the provision of these bypass structures uses to pass flood at saddle points. meanwhile, numerous saddle points are situated along the reservoir entrance. fortunately, there is neither population nor as such vast properties found at the downstream side of the saddle point. the method is also appropriate for earthen dams which are susceptible to the flood. the researcher concludes by recommending to conduct further modeling studies of the inflowstorage-outflow of the reservoir by taking different flood estimation methods. in addition to this, during the 100 years’ service time of the dam, the sediment impact is not as such tolerable. so, further researches have to be conducted because it will reduce the effective storage of the reservoir. fig. 5 the designed emergency spillway cross-sectional profile 40 shumie 2019 / journal of environmental geography 12 (1–2), 33–40. references abaya, s. w. 2008. floods and health in gambella region, ethiopia: an assessment of the strength and weakness of the coping mechanism. m.sc. thesis, lund university. available at: https://www.lumes.lu.se/sites/lumes.lu.se/files/samson_abay a.pdf arora, k. r. 2012. irrigation, water power and water resources engineering. standard publisher distribution, delhi. isbn: 81-8014-007-5. 1106 p asfaw, h. b., essen, p. v., tsige, t.z. 2014. background information for a program approach challenges and possible cooperation between dutch and ethiopia counterparts integrated water resources management upper awash river basin, central ethiopia. waterschap. online available at: http://www.waterethiopia.org/wpcontent/uploads/2014/03/background-information-for-aprogram-approach-challenges-and-possible-cooperationbetween-dutch-and-ethiopia-counterparts.pdf botto, a., ganora, d., laio, f., claps, p. 2014. uncertainty compliant design flood estimation. water resources research 50 (5) 4242–4253. doi: 10.1002/2013wr014981 chow, v. t., maidment, d. r., mays, l. w. 1988. applied hydrology. the mcgraw-hill companies. new york, 572. cowin, m. w., bardini, g. b. 2011. central valley flood protection plan. floodsafe, california. online available at: https://water.ca.gov/legacyfiles/floodsafe/fessro/docs/floo d_tab_cvfpp.pdf garg, s.k. 2006. irrigation engineering and hydraulic structures. khanna publishers, delhi, india. 1184 p. haile, a. t., kusters, k., wagesho, n. 2013. loss and damage from flooding in the gambela region, ethiopia. international journal of global warming 5(4) 483–497. doi: 10.1504/ijgw.2013.057290 hudson, h. r., harding, j. s. 2004. drainage management in new zealand. wellington: department of conservation. 39p. onwuka, s., ikekpeazu, f. o., onuoha, d. c2015. assessment of the causes of 2012 floods in aguleri and umuler, anambra east local government area of anambra sstate, nigeria. british journal of environmental sciences 541, 43–57. ranghunath, h. 2006. hydrology: principle, design and analysis.: new age international (p) limited, new delhi, 476 p. salas, j. d., govindaraju, r. s., anderson, m., arabi, m., france´s, f., suarez, w. 2014. introduction to hydrology. in: wang l.k. , yang c. t. modern water resources engineering, 1–126. . doi: 0.1007/978-1-62703-595-8_1 shemeles, p. 1998. establishing water release rules for koka reservoir for wet seasons. msc theses, addis ababa: addis ababa university, online available at: http://etd.aau.edu.et/handle/123456789/2070?show=full shaw, e. m. 2005. hydrology in practice. london, taylor and francis e-library, 613 p. stephens, d. b. 2012. sonoma valley stormwater management and groundwater recharge scoping study screening evaluation and prioritization memorandum, 1-46. online available at: http://www.scwa.ca.gov/files/docs/projects/stormwatergroundwater/sonoma_scoping_screening_memo_finalmemo+plates.pdf suykens, c., priest, s. j., van doorn-hoekveld, w. j., thuillier, t., rijswick, m. v. 2016. dealing with flood damages: will prevention, mitigation, and ex post compensation provide for a resilient triangle? ecology and society 21(4), 1–17. doi: 10.5751/es-08592-210401 wobus, c., gutmann, e., jones, r., rissing, m., mizukami, n., lorie, m. 2017. climate change impacts on flood risk and asset damages within mapped 100-year floodplains of the contiguous united states. natural hazards and earth system sciences 17, 2199–2211. doi: 10.5194/nhess-17-2199-2017 wwdse, 2006. hydrologic design report of kesem kebena dam and irrigation project. water works design supervision enterprise, addis ababa, ethiopia. https://doi.org/10.1504/ijgw.2013.057290 introduction study area data and methods meteorological data collection reservoir and spillway maximum monthly rainfall peak inflow discharge monthly outflow volume monthly excess water volume emergency spillway design spillway design computations ogee crest design results and discussion maximum monthly rainfall computing excess flood volume ogee profile and hydraulic design conclusion references environmental status of a city based on heavy metal content of journal of environmental geography 12 (1–2), 13–22. doi: 10.2478/jengeo-2019-0002 issn 2060-467x environmental status of a city based on heavy metal content of the tree-rings of urban trees: case study at szeged, hungary tímea kiss*, istván fekete, ibolya tápai department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6., h-6722 szeged, hungary *corresponding author, e-mail: kisstimi@gmail.com research article, received 11 december 2018, accepted 2 february 2019 abstract urban vegetation, especially urban trees could act as ecological archives, as they reflect various elements of their environment. the main aim of the study is to evaluate the spatial and temporal variations of environmental conditions in the city of szeged (hungary) based on long-term monitoring of the heavy metal content of tree-rings (soft wood). in general, the living conditions of the urban trees (and other organisms as well) at szeged was the worst in 2001/05, when the heavy metal pollution was the greatest, therefore the biomass production of the sampled trees decreased. fortunately, the environmental conditions became better, only there are so me points in the industrial area, where the heavy metal pollution of the environment is gradually increases. the temporal change in lead pollution (considerable decline in 2013/17) could be explained by the obligatory usage of lead-free petrol since 1999 and the diversion of through-traffic from the town (2011). the introduction of unleaded petrol had delayed favourable results, as the dust particles containing lead probably circulated in the air for a while before they were gradually become fixed in the soil or they were washed out from the town during heavy rains. the cadmium pollution also declined after the traffic diversion, as it is connected to the usage of brake-linings. whilst the lead and cadmium content of the tree-rings decreased during the studied decades, the trees accumulated increasing amount of zinc throughout the studied periods, as this element could be up-taken from the ground-water, as the larger the canopy of a tree the denser and deeper its root system is. keywords: heavy metal, pollution, urban vegetation, environmental stress, long-term monitoring introduction urban vegetation is exposed to various noxious environmental effects, especially along busy roads. the most important disturbances are related to (1) increased air and soil pollution in connection to traffic and heating; (2) compaction and burial of soils, which decrease the water availability and impede the transpiration of the rootsystem; (3) mechanical injuries; (4) extreme waterhousehold and temperature conditions in connection to urban heat-island and built-in areas; and (5) extra salt input into soils linked to defrosting of roads during winter (gulyás and kiss, 2007). these disturbances are usually overlapped aggrading each-other’s effects, and leading to growth irregularities and water-household imbalances (ballach et al., 1998). at the same time the state of the urban vegetation reflects the environmental status of an area, which is related to the social, economic, cultural and health status of an urban neighbourhood (lányi, 2000). urban vegetation, especially urban trees could act as ecological archives, as they reflect various elements of their environment (alestalo, 1971; kern and popa, 2009), therefore they could be used to map the environmental status of urban areas and to identify those neighbourhoods which are more prone to environmental load. the main aim of the study is to evaluate the spatial and temporal variations of environmental conditions in the city of szeged (hungary) based on the heavy metal content of tree-rings (soft wood). in the frame of the research we had sampled urban trees, as (1) they indicate the amount of heavy metals which could b ioaccumulate in the living organisms, (2) the tree -rings reflect the temporal changes of (air) pollutants, and (3) the tree-rings could be repeatedly sampled without hurting the tree itself. heavy metals could get in into the tree-rings through the leaves, the root-system or the bark, but the ratio between these uptakes is different depending on the species or local factors (lepp, 1975). however, the most important route of heavy metal uptake is through leaves (lin et al., 1995), but it is not proven in case of all urban species (watmough, 1999). despite of the uncertainties, the tree-rings are declared to be good archives of atmospheric fallout of heavy metals, thus the pollution history (brabander et al., 1999; watmough, 1999; padilla and anderson, 2002), or the spatio-temporal variations in traffic could be reconstructed based on a dendrological study (kadell and larsson, 1978). specific aims of the research were to found an urban bio-monitoring system at szeged, to monitor the spatial and temporal changes in heavy metal load, and to evaluate the environmental status of the city. the monitoring system was founded at szeged in 2000 involving 75 urban trees, which represent the entire area of the city, and the same specimens were sampled three times, thus the pollution history of a relatively long period (1996-2017) could be reconstructed. 14 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. study area the city of szeged is located on the hungarian great plain, close to the romanian and serbian border (fig. 1). therefore, the international transit traffic through the town was considerable, thus the airand dust pollution originating from traffic have reached the health limits at certain times (pasinszki, 1996). however, the traffic situation had changed in 2011, when a ring-road highway (m43) was built, thus the roads became less busy within the town. another factor, which could have influenced the environmental load is the usage of lead-free petrol, which became obligatory in hungary in 1999. the industrial activity in the town is limited, only some chemical, food and textile companies operate, however it is surrounded by agricultural fields. the city is dissected by the tisza river, which influences the ground-water conditions. it could affect the heavy metal accumulation of the trees too, as north of the town the maros river joins to the tisza. this tributary transports large amount of pollutants (mainly copper and zinc; kiss and sipos, 2001) originating from the geological background of the catchment and from mining activity (waijandt and bancsi, 1989). methods sample collection tree-ring samples were collected from the entire area of the city with almost equal spatial distribution in 2000, 2005 and 2017 (fig. 1). during the planning of the bio-monitoring system such tree species had to be selected, which (1) are abundant in the whole city; (2) accumulate heavy metals in the same manner and rate; and (3) were affected by similar environmental effects (e.g. situated along roads). these criteria were fulfilled by tilia platyphyllos and populus nigra ssp. italica. if the individuals of the two species appeared next to each other, we sampled both of them, to compare the differences in their heavy metal bioaccumulation. during the first field campaign 73 trees were sampled. later some of the trees were cut, therefore in 2005 only 67 of them existed, and in 2017 only 57 remained. at each sampling campaign the same individuals were sampled to decrease the errors originating from the different (1) metabolism of individuals; (2) location; and (3) exposure. to evaluate the spatial changes of heavy metal pollution along roads, two main roads with heavy traffic were sampled (bajai road and kossuth road). to evaluate the effective distance from a main busy street the trees along a quiet street (eszperantó str.) joining to a main road were also sampled. the trees were sampled by increment borer (lintab, denmark) at 1.0 m height above ground (figs. 2-3), at the side of the trunk facing towards the road. during each sampling campaign the outer 5 tree-rings (located in the soft wood) were separated, representing the periods of 1996-2000, 2001-2005, and 2013-2017. samples were dried (moisture content <5%), and their weight (ranging between 0.5-2.0 g) was measured, so later we could evaluate the biomass production of the trees. analytical measurements the samples represent a 5-year period, thus the heavy metal (pb, cd, cu and zn) content (ppm) is a mean value for the period. the sample preparations during each campaign were made in the same way. the tree-ring samples were treated in nitric acid (65%) for 24 hours, later they were boiled for 3 hours on 120°c, finally they were treated by hclo4 (70%). though the sample preparation was the same, the analytical devices changed during the study. the first two measurements were made using perkin elmer 3110 fig. 1 location of szeged (hungary) and the sampled urban trees kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. 15 atomabsorptic and emission spectrometer, whilst the last measurement was made by perkin elmer 7000dv icp-oes spectrometer. based on simultaneous tests, there is no considerable difference between the results of the two devices, though the second one has much better resolution. fig. 2 the trees were sampled by increment borer fig. 3 location of former cores and the latest coring at the same poplar tree spatial analysis of the results based on the range of heavy metal content of the tree rings, the samples were divided into five even classes. the members of class no. 1. contain the lowest amount of certain heavy metal, while trees belong to the class no. 5 accumulated the greatest amount of a given heavy metal. to evaluate the total heavy metal load of a tree and to evaluate the environmental status of the area, the indices of the classes were summarized, and reclassified. in this way the total environmental load of an urban tree at a given location and at a given time could be evaluated (very good / good / medium / satisfactory / bad). results biomass changes of the tree-rings the weight or width of tree-rings refers the biomass production of a tree, which reflects its living conditions and the rate of environmental load of the area. in the first period (1996/2000) the mean weight of the 5 tree rings was 0.29 g (fig. 4), and it reduced to 0.22 g in the next period (2001/05). this considerable decrease (-28%) undoubtedly refer to the declining living conditions of the sampled urban trees. in the last period (2013/17) the mean value did not decrease further on, and some trees even could increase their biomass. these trees are usually along quiet roads where the water supply is more favourable (e.g. less paved surfaces). fig. 4 weight changes of the sampled 5 tree-rings (representing the maximum, mean and minimum values) temporal changes in heavy metal pollution of tree-rings the amount of accumulated heavy metals considerably changed during the studied period (table 1). between the first and second survey the mean lead (pb) and zinc (zn) content increased by 2-3 times, whilst of the cadmium (cd) and copper (cu) by one order. at the same time the minimum and maximum vales became more similar, reflecting, that whilst in the first period some sites were polluted and others could be considered as unpolluted, in the second period the entire city was more evenly and higher polluted. however, by the third survey (2013/17) the situation improved. the lead pollution decreased by 97% compared to the previous period. the amount of cadmium has also declined by 96%. similar decrease was detected in case of copper (-88%). however, the amount of zinc gradually increased: until the early 2000s its amount tripled (+288%), and until nowadays it increased by further 51%. the heavy metal content of the tree-rings increased at almost every sampling point in the second period (2001/05), however in the third period (2013/15) it decreased. to visualise these changes, the heavy metal content of tree-rings in a period was plotted against the next period (fig. 5 a, b). table 1 temporal changes in heavy metal content (ppm) of the tree-rings lead (pb) cadmium (cd) copper (cu) zinc (zn) 19962000 20012005 20132017 19962000 20012005 20132017 19962000 20012005 20132017 19962000 20012005 20132017 min 0.0 6.2 0.0 0.0 2.8 0.0 0.0 0.6 1.2 0.0 0.5 4.2 mean 6.4 11.0 0.3 0.3 5.0 0.2 2.3 27.0 3.4 4.4 12.7 19.3 max 47.7 21.0 1.0 3.6 9.1 1.0 48.9 338.2 20.2 55.1 37.2 82.2 16 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. in case the rate of bio-accumulation of the have metal remains the same, the point representing a tree should fit to the x = y equation (line). comparing the results of the first and second period reflects that almost all points fall above the line in case of all studied heavy metals, referring to increased bioaccumulation of these elements in the tree-rings. in contrary, the comparison of the second and third period reflects that the points usually fall below the line in case of lead, cadmium and copper, thus their uptake and accumulation in the trees decreased. the exception is the zinc, as in 60% of the sampled trees its concentration had increased even in the third period. spatial distribution of the studied heavy metals spatial distribution of lead pollution the usage of lead-free petrol became obligatory in hungary after 1999, thus the studied timeframe represent a period (1) when considerable amount of pb was emitted to the environment by traffic (1996/2000), (2) consequently after the banning of leaded petrol (2001/05), and finally (3) when (2013/17) the recovery of the environment was more advanced and no lead of traffic origin could get in the air. as most of the lead pollution is considered to have traffic origin, we evaluated it from three different points: (1) spatial distribution in the entire city; (2) along the main traffic routes; and (3) by the distance from a busy road. in the first period (1996/2000) the lead pollution of the city was low in general, as at 64% of the sampling sites its concentration was below 5 ppm (fig. 6). however, in 2001/05 it increased, at in all cases it was above 5 ppm. the most polluted areas were along the busy roads, despite of the fact, that at this time the usage of lead-free petrol was already obligatory in hungary. by the third period (2013/17) the lead content of all sampled trees reduced bellow 5 ppm, reflecting better environmental conditions in the entire city. fig. 5 comparison of a) lead and b) zinc content (ppm) of the tree-rings measured at the different periods. if a point falls below the line, the concentration decreased by time, but if it is above, the concentration increased compared to the previous period. fig. 6 spatial distribution of lead content (ppm) in tree-rings at szeged in the periods of 1996/2000, 2001/05 and 2013/2017 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. 17 along the studied busy roads, the lead content of the tree-rings was high during the first two periods, almost twice as much than in those in the quiet streets and parks. however, during the last period the differences were not so high, though the along the busy roads the trees had higher lead accumulation. along the bajai road the lead content increased towards the city centre (fig. 7a), parallel to the increasing amount of built-in areas and the lack of ventilation. however, the trees along the kossuth road refer to another trend. in this case the lead content increases towards the city centre, however it is broken at the circular roads which divert considerable amount of the traffic. the efficiency of lead pollution dispersal from the main, busy road was studied along relatively qui et street (eszperantó str) perpendicular to a busy road (kossuth road). in the first period (1996/2000) the sampled trees within 25 m distance from the main road accumulated almost the same amount of lead (fig. 7b), only at 30-40 m far from the main road the accumulation started to decrease. the pattern of the pollution was similar in 2001/05, though the trees accumulated much more lead. spatial distribution of cadmium pollution in 1996/2000 cadmium content above the detection limit (2.0 ppm) was measured in 31% of the trees, mainly along the busy roads. its amount increased in 2001/05, as even in the small parks and quiet streets its amount was above 2.0 ppm. in the first period cadmium appeared just at the busy cross -roads of the city centre, but in 2001/05 it was detectable everywhere, especially along the main roads (fig. 8), similarly to the spatial distribution of the lead (fig. 5). in the third period (2013/17), the lead content decreased in every sampled tree to 0.01 -1.3 ppm, though it still appeared everywhere. the cadmium pollution of the city – similarly to the lead pollution – was characteristic in the entire territory of the city, though lately less accumulated in the living organisms. the spatial distributions of lead and cadmium reflect that both pollutants have the highest values at the same places. it could be explained by their origin, as both are related to traffic. the cadmium is emitted through the wearing of tires and burning of diesel fuel (csathó, 1994). in the first period (1996/2000) cadmium pollution did not get into the quiet streets, thus no cadmium accumulated in the trees of the side street (eszperantó str.). however, in the next period (2001/05) it was already detectable, and its amount only slightly decreased (from 6.00 ppm to 4.15 pp) with the decreasing distance from the main road. spatial distribution of copper pollution in the first period (1996/2000), the copper co ntent of the tree-rings was below 5.0 ppm in 97% of the samples. the highest values (18.6 ppm and 48.9 ppm) were measured in the nw part of the city, in an industrial area, therefore, we assumed, that it had in industrial origin. though in this area the pollution decreased in 2001/05, but all over the city the copper content of the tree-rings has increased, and the most polluted areas shifted from the industrial area towards se and to the city centre (fig.9). only 14% of the trees accumulated less than 5.0 ppm of copper, and extremely high values (100-338 ppm) appeared in 5 trees, four of them located in the city centre. at the same time, newer polluted areas appeared in the n and sw parts of the city, where the trees accumulated 20 40 times more cu than before. in the last period (2013/17) the copper pollution dropped, as in most of the trees the copper content d ecreased bellow 5.0 ppm. only one tree, in the nw industrial area accumulated 20 ppm copper spatial distribution of zinc pollution among the studied pollutants only the amount of zinc has increased throughout the three studied periods, thus the zinc pollution is getting worse in szeged (fig. 10). in the first period (1996/2000) 86% of the trees accumulated less than 10 ppm of zn, and only two trees had high zinc content (55 ppm and 34 ppm). in the next period (2000/2005) only 40% of the trees accumulated less than 10 ppm. in the latest period (2013/17) the zn content of the tree -rings increased further on, only 12% of the trees had less than 10 ppm zn. these trees are located in the city centre and in the suburb of újszeged. especially high amount of zinc (57-82 ppm) was found in the trees located in nw part of the city. fig. 7 lead pollution along the busy kossuth road towards the city centre in the first period (1996/2000; b) lead content of the tree-rings in the quiet eszperantó street, perpendicular to the busy kossuth road in 1996/2000 18 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. fig. 8 spatial distribution of cd content (ppm) in tree-rings at szeged in the periods of 1996/2000, 2001/05 and 2013/2017. fig. 9 spatial distribution of cu content (ppm) in tree-rings at szeged in the periods of 1996/2000, 2001/05 and 2013/2017 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. 19 discussion spatial and temporal changes in heavy metal bioaccumulation in general, the living conditions of the urban trees (and other organisms as well) at szeged was the worst in 2001/05, when the heavy metal pollution was the greatest, therefore the biomass production of the sampled trees decreased (-28%). it is parallel to the results of fischer et al. (2002), who found negative correlation between treering width and its lead content. however, the living conditions of the trees in szeged did not become more favourable ever since, nor it became worse, as the biomass of the tree-rings remained the same. this reflects that despite of the decline in heavy metal pollution some other stress factors became stronger, creating unfavourable urban environment for the trees. probably the low woodbiomass is connected to the hotter and drier summers (ladányi and blanka-végi, 2015), as szeged is the hottest city in hungary. the temporal change in lead pollution (considerable decline in 2013/17) could be explained by the obligatory usage of lead-free petrol. in hungary it is used since 1999, but no data exists for the neighbouring countries (romania and serbia), though the international traffic through the city was high until 2011, when a circular highway was built to divert the through-traffic from the town., though some years had to be passed to eliminate from the air. thus, the first period (1996/2000) was characterised by intensive lead emission, and during the second period (2001/05) its amount was supposed to decrease. however, the comparison of the periods suggests, that the introduction of unleaded petrol had delayed favourable results, as by 2001/05 the lead content of the tree-rings increased by 3-4 times, and it decreased just later, in the third period. this could be explained by the fact, that lead is connected to small dust particles (pasinszki, 1996), these particles just gradually became fixed in the soil or they were washed out from the town during heavy rains, thus these particles probably circulated in the air for a while. the extended presence of the lead in the air was also proven in 2005 (csemete association, unpublished report, 2006). this temporal lag of lead output from the city suggests, that the lead (and also other heavy metals) could be-mobilised repeatedly in the city, thus it was repetitively available for foliage uptake for the trees much longer, then it was expected. the cadmium pollution also declined in 2013/17, after the international traffic was diverted from the city. the cadmium pollution is connected to the usage of brakelinings (grigoratos and martini, 2015), thus as the transittraffic decreased after the construction of the m43 highway in 2011, much less cadmium could get in the air. along the studied busy roads, the bio-accumulation of lead in tree-rings was twice as much as along less busy roads during the first and second period, fitting to former european studies (watmough, 1999). in the third period the differences in lead content was smaller, however its fig. 10 spatial distribution of zn content (ppm) in tree-rings at szeged in the periods of 1996/2000, 2001/05 and 2013/2017 20 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. spatial trend was the same. along the quite busy bajai road and kossuth road the lead concentration gradually increased towards the city centre, though at kossuth road it decreased at a large junction (fig. 8.). this phenomenon reveals, that the outer ring-roads, which divert the traffic, play important role in decreasing the environmental load of a city. this phenomenon points on the importance of road diversions, which could be applied to decrease the environmental load of the heavily built-in areas, as in these cases the narrow and badly ventilated streets enclosed by high houses trap the dust particles containing lead. this idea is supported by the measurement of pasinszki (1996), who found positive linear correlation between the rate of deposited dust and the lead pollution of the air. in our case the pollutants were dispersed further from the busy road, then it was reported in the literature, as according to kardell and larsson (1978) the busy roads effect the pollution of the side roads just within 20-25 m buffer zone, while at szeged the effective distance is ca. 30-40 m. whilst the lead and cadmium content of the treerings decreased during the studied decades, the trees accumulated increasing amount of zinc throughout the studied periods. nor the zinc, neither the copper content of the tree-rings reflects any spatial tendency along the main roads, thus they are not related to traffic. according to the data their concentrations are proportional to the age of the tree, the size of the canopy and root system. thus these elements either could be deposited from the air and in this way they got onto the leaves and into the tissues, or could be up-taken from the ground-water, as the larger the canopy of a tree the denser and deeper its root system is. unfortunately, no data exists on the air pollution of the city, but presumably the copper pollution originated from an agricultural activity, as copper is often used in pesticides. the greatest zinc pollution characterised the trees growing at the outskirts, along the tisza river and an ox-bow-lake of the maros river. thus, probably the zinc was transported to the town by wind or by ground water. the root-uptake could be verified by the fact, that the water and the sediment of the maros river contains large amount of zinc (waijandt and bancsi, 1989; kiss and sipos, 2001), and also the ground water has high zinc content (fejes 2014). relationship between the type of built-in areas and heavy metal content the spatial distribution of the studied heavy metals was compared to the built-in types of the city, referring to the environmental load of a given area, thus to the life conditions of the citizens. some heavy metals were deposited from the air and were built into the tree-rings through leaf-uptake, probably similar rate of heavy metals could get into the human body through inhalation. it is especially valid for the lead and cadmium pollution, which are both closely related to the traffic and its dust production. the mean heavy metal pollution of the densely built-in city center was relatively low in 1995/2000 and 2013/17 (fig. 11). it could be probably explained by the shading effect of the tall, densely built detached houses, thus the pollution could not spread far from the sources. however, in the period of 2001/05 this area became polluted. until 2005 the lead-born environmental risk of this area was closely related to traffic and to the usage of leaded petrol, but only those areas and living organisms were closely affected, which located in 50-60 m distance from the main roads, or at local or regional bus stations. the environmental status of the northern living areas with block-of-flats is relatively good, except along the busy roads, where the data of the first two measurement periods refer to medium of moderately bad pollution. however, the environmental status of these areas also improved. some parts of the suburban areas are the most polluted. toward the industrial area and the city centre (rókus, alsóváros suburbs) the environmental load increased until 2001/05, but since that time these areas became less polluted. in general, the south-eastern part of the town (újszeged) is the less polluted. relatively large concentrations were built only along the roads or at some points, where previous waste disposals or traffic junctions were located. the northern industrial area is the most polluted, though the other small industrial centres are also characterised by high values. these are such a places of the town, where though the absolute heavy metal concentrations in tree-rings is decreasing, but these concentrations compared to the other parts of the city are still high. in these neighbourhoods housing is rare, thus these areas are responsible for relatively low environmental risk for humans. it could be stated, that the tissues of urban trees, as living organisms, reflect considerable changes in spatial and temporal dispersal of pollutants. in the first period (1995/2000) the city of szeged was characterised by low heavy-metal load, but during the next period (2001/2005) the situation considerably became worse, as heavy metals appeared in all studied trees all over the city, and even worse than that, their amount was multiplied. fortunately, the environmental conditions became better, only there are some points in the industrial area, where the heavy metal pollution of the environment is gradually increases. conclusions according to former researches (lepp, 1975, kardell and larsson, 1978; temminghoff et al., 1998) the copper, cadmium and lead uptake of trees is the greatest through the foliage. some metals could be relatively mobile in the soil, however, only at low ph values (csathó, 1994), but the soils in szeged city are slightly basic or basic (fejes, 2014). therefore, at szeged the heavy metals above probably originated from air pollution, and they got into the tree-rings through foliage uptake. this is also supported by the spatial distribution of pollutants within the city, and their temporal changes. the heavy metal content of tree-rings considerably increased in the second period, in 2001/05, compared to the previous and subsequent periods. while in the first period only some sampling points were considered as polluted, in 2001/05 the urban environment of szeged was affected by higher and more uniform heavy metal kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. 21 pollution. the deteriorating life conditions are also shown by the declining biomass. though the environmental hazard due to heavy metal pollution seems to be reduced, other factors (e.g. drought, heatstress) increase the exposure of urban trees to environmental stress, thus the tree-ring width and biomass production remained low. the spatiality of heavy metal concentrations in tree-rings refers to the variations in environmental load of the various parts of the city. the greatest amount of pollutants was measured in trees along the busy main roads and in the north-western part of the city. some parts of the heavy metal pollution (lead and cadmium) is undoubtedly originates from traffic, while other parts (copper and zinc) originates from other (yet unknown sources) and the trees can accumulate them through the root-system (from groundwater) or the leaves (from air). as the lead and cadmium pollution mainly appear along within 30-40 m buffer zone of main roads and busy junctions, the environmental status of these areas improved since the usage of unleaded petrol and the diversion of international through traffic. the spatial pattern of some heavy metals (copper and zinc) is changing by time, and in case of zinc more and more sampling sites are polluted, and the degree of pollution also increases. this researched proved, that a long-term biomonitoring study is a useful tool to analyse the spatial and temporal changes of the environmental risk, which does not only determine the living conditions of urban trees, but also influences the quality of the human environment. acknowledgements the authors are thankful for prof. gábor mezősi for the basic idea of the research, and for z. jóri, m. szatmári and a. borah for their help during the field campaign and for their laboratory work. the final period of the research was supported by efop-3.6.1-16-2016-00008 grant. references alestalo, j. 1971. dendrochronological interpretation of geomorphic processes. fennia 105, 1–146. ballach, h.j., goevert, j., kohlmann, s., wittig, r. 1998. comparative studies on the size of annual rings, leaf growth and the structure of treetops of urban trees in frankfurt/main. in: breuste, j., feldmann, h., uhlmann, o. (eds): urban ecology. springer, 699– 712. brabander, d.j., keon, n., stanley, r.h.r., hemond, h.f. 1999. intraring variability of cr, as, cd, and pb in red oak revealed by secondary ion mass spectrometry: implications for environmental biomonitoring. pnas 96, 14635–14640. doi: 10.1073/pnas.96.25.14635 csathó, p. 1994. a környezet nehézfém szennyezettsége és az agrártermelés. mta fki budapest 175 p. fejes, i. 2014. a talajés talajvízrendszer komplex környezeti szempontú értékelése városi területen, szeged példáján. phd thesis, university of szeged, 142 p. fischer, s., nicholas, n.s., scheuerman, p.r. 2002. dendrochemical analysis of lead and calcium in southern appalachian american fig. 11 changes in environmental status of the sapling points based on the summarised heavy metal load of the tree-rings https://doi.org/10.1073/pnas.96.25.14635 22 kiss et al. 2019 / journal of environmental geography 12 (1–2), 13–22. beech. j. environ. qual. 31. 1137–1145. doi: 10.2134/jeq2002.1137 gulyás, á., kiss, t. 2007. városi élőhelyek és élőlények. in: mezősi, g. 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(eds): a táj megértése felé. de, debrecen, 63–83. ladányi, zs., blanka, v. 2015. tree-ring width and its interrelation with environmental parameters: case study in central-hungary. journal of environmental geography 8(3-4), 53–58. doi: 10.1515/jengeo-2015-0012 lányi, g. 2000. településkörnyezet: a természet a településben in: enyedi, gy. (ed): magyarország településkörnyezete. mta, budapest, 99–151. lepp, n.w. 1975. the potential of tree-ring analysis for monitoring heavy metal pollution patterns. environ. pollut. 9, 49–61. doi: 10.1016/0013-9327(75)90055-5 lin, z.q., barthakur, n.n., schuepp, p.h., kennedy, g.g. 1995. uptake and translocation of 54mn and 65 zn applied on foliage and bark surfaces of balsam fir seedlings. env. exp. bot. 35, 475–483. padilla, k.l., anderson, k.a. 2002. trace element concentration in treerings biomonitoring centuries of environmental change. chemosphere 49, 575–585. doi: 10.1016/s00456535(02)00402-2 pasinszki, j. 1996. levegőhigénés mérések szegeden az ülepedő por elemzésével 1993 nyarán. csmtve évkönyve ii. 62–76. temminghoff, e.j., plette, a.c., van der see s.e.a, van riemsdjik w.h. 1998. availability and mobility of heavy metals in contaminated soils. in filep, gy. (ed) soil pollution. debrecen, 85–103. waijandt, j., bancsi, i. 1989. a tisza és mellékfolyói vizének és üledékének nehézfémtartalma. hidrológiai közlöny 69, 83–88. watmough, s.a. 1999. monitoring historical changes in soil and atmospheric trace metal levels by dendrochemical analysis. environmental pollution 106, 391–403. doi: 10.1016/s02697491(99)00102-5 http://www.geo.u-szeged.hu/journal/?q=node/9 http://www.geo.u-szeged.hu/journal/?q=node/9 http://www.geo.u-szeged.hu/journal/?q=node/9 introduction study area methods sample collection analytical measurements spatial analysis of the results results biomass changes of the tree-rings temporal changes in heavy metal pollution of tree-rings spatial distribution of the studied heavy metals discussion spatial and temporal changes in heavy metal bio-accumulation relationship between the type of built-in areas and heavy metal content conclusions acknowledgements references journal of environmental geography journal of environmental geography 6 (1–2), 29–36. doi: 10.2478/v10326-012-0004-2 issn: 2060-467x evaluation of groundwater quality using water quality indices in parts of lagos-nigeria isaiah s. akoteyon department of geography and planning, lagos state university,ojo, p.m.b. 1087, apapa, lagos e-mail: sewanuakot@gmail.com research article, received 14 january 2013, published online 15 april 2013 abstract water samples collected from forty-five hand dug wells and thirteen boreholes using random sampling technique were measured for ph, electrical conductivity and total dissolved solids. calcium, chloride, bicarbonate and carbonates were analyzed using titrimetry method. magnesium, potassium and sodium by atomic absorption spectrophotometer (aas) and sulfate was analyzed using a spectrophotometer. the study aims to evaluate groundwater quality using water quality indices in parts of lagos-nigeria. the sample locations and spatial variations in the concentration of bicarbonates, revelle and water quality indices were mapped using surfer 6.0 software. the result shows that ph indicate extremely acidic to strongly alkaline condition, ec shows medium and high enrichment of salts from location 28 and 21 respectively. spatially, about 31% and 29.3% of bicarbonate are under poor and moderate zones respectively. the computed revelle index shows that 41.4% and 1.7% are slightly and strongly influenced by groundwater salinization respectively. unlike the water quality index, about 12.1% and 1.7% indicate poor and water unfit for drinking respectively. the paper concludes that groundwater salinization is on the increase since over half of the samples are influenced by salinity. unlike the water quality, it was concluded that the water is of good quality since about 86.2% is suitable for drinking purposes. based on these findings, it was recommended that waste water treatment and disposal methods should be avoided and appropriate treatment methods to make it more potable and fit for human consumption should be employed in critical locations of the study area. keywords: groundwater, lagos-nigeria, water quality, revelle index, water quality index introduction fresh water, as a valuable and finite resource, is a central issue of sustainable development, economic growth, social stability, and poverty alleviation. fresh water quality has grown to become the major international issue in recent years (rejith et al., 2009). urban growth, increased industrial activities, intensive farming, and overuse of fertilizers in agricultural production have been identified as drivers responsible for these changes (patwardhan, 2003). studies have shown that the polluted environment has a detrimental influence on human health, fauna and flora species (sujatha and reddy, 2003). contamination of groundwater (resulting from human activities or from inherent aquifer material) impairs water sources and poses threat to public health (renji and panda, 2007). rapid population growth and increased anthropogenic activities result in huge discharge and diverse pollutants reaching sub-surface water. excessive groundwater withdrawals have been reported to result in hydro-chemical changes in the physical, chemical and microbiological water quality, decline of the water table, reverse hydraulic gradient and consequently water quality deterioration in coastal areas (esteller et al., 2012; jamshidzadeh and mirbagheri, 2011). poor water quality results in incidences of waterborne diseases and consequently reduces the life expectancy (who, 2006). thus, concern for clean and safe drinking water and protection from contamination is justified because a large proportion of the population in the study area depends on sub-surface sources e.g. dug wells and boreholes etc. for domestic and drinking uses. water quality evaluation is based on the physical, chemical and biological parameters ascertaining the suitability for various uses such as consumption, agricultural, recreational and industrial use (boyacioglu, 2007; sargaonkar and deshpande, 2003). traditional methods of assessing water quality are based on the comparison of experimentally determined parameter values with existing guidelines. this method allows proper identification of contamination sources essential for checking legal compliance (boyacioglu, 2007). one of the advantages of water quality index (wqi) is that it serves as a useful and efficient method for assessing the suitability of water quality for various purposes. it also serves as a mean of communicating information on the overall quality of water using a single number both temporarily and spatially (christiane et al., 2009; boyacioglu, 2007). water quality indicators have been applied to assess the overall water quality in different parts of the mailto:sewanuakot@gmail.com 30 akoteyon (2013) globe efficiently (bharti and katyal, 2011). these indicators are based on the comparison of water quality parameters using regulatory standards to give a single value to the water quality of a source. wqi computation involves four steps: parameter selection, development of sub-indices, assignment of weights and aggregation of sub-indices to produce an overall index. wqi helps to reveal the temporal and spatial variation of water quality (bharti and katyal, 2011). it also serves as a useful tool for summarizing large amounts of water quality data into simple terms such as excellent, good, bad, etc. for easy communication to the public. literature abounds on water quality assessment. akoteyon et al. (2010), yidana and yidana (2010), akoteyon and soladoye (2011), jamshidzadeh and mirbagheri (2011), partey et al. (2010), celik and yildirim (2006) mishra et al. (2005), edmunds et al. (2003) among others applied wqi in evaluating groundwater. for instance, shah et al. (2008) co mpared groundwater quality in gandhinagar taluka in india and developped the water quality index for the area. zaharin et al. (2009) classified salinization of groundwater in the shallow aquifer of a small tropical island in sabah, malaysia using revelle index (i.e. cl / (hco3 + co3). lobo-ferreira et al. (2005), chachadi and lobo – ferreira (2001) also adopted this index to evaluate seawater intrusion into the coastal aquifer in india. thus, this study is aimed at evaluating groundwater quality using water quality indices in parts of lagos-nigeria as an alternative method for disseminating information on water quality status using indices for better understanding both by the public and relevant agencies. study area the study area is located approximately between latitudes 6 o 23’ 30’ n and 6 o 34’15 n and longitudes 3 o 28’0 e and 3 o 38’45 e . it is bounded in the east by ibejulekki, in the north by the lagos lagoon and in the south by the atlantic ocean and parts of the metrop olis in the west. the climate is tropical, hot and wet and the area is characterized by coastal wetlands, sandy barrier islands, beaches, low-lying tidal flats and estuaries (adepelumi et al., 2009). the average temperature is about 27 0 c with an annual average rainfall of about 1,532 mm (adepelumi et al., 2009). the major seasons are the wet and dry seasons. the wet season lasts for 8 months (april to nove mber) and the dry season covers a period of 4 months (december to march (adepelumi et al., 2009). the dominant vegetation consists of tropical swamp forest (fresh waters and mangrove swamp forests and dry lowland rain forest). the area is drained by lagos lagoon (emmanuel and chukwu, 2010). the geology is underlain by the benin formation and is made up of highly porous sand and gravel with thin shale/clay inter-beds (oteri and atolagbe, 2003). the groundwater flow direction shows a general north to south direction with two small cones of depression in apapa and ikeja because of intense groundwater extraction (coode et al., 1997; oteri and atolagbe, 2003). the hydrogeology is characterized by unfossiliferous sandstone and gravel weathered from unde rlying precambrian basement rock (longe, 2011). it consists of abeokuta and ewekoro formations, coastal plain sands (cps) and recent sediments. the cps aquifer is the most productive and exploited aquifer in lagos state. cps is categorized into four types namely the recent sediments, the second and third aquifers also known as (upper and lower) cps aquifer and the fourth aquifer is the abeokuta formation (longe, 2011). the upper coastal plain sand aquifer (ucps) is a water table aquifer and ranged from 0.4–21m below ground level with a relatively annual fluctuation below 5m (asiwaju-bello and oladeji, 2001). this aquifer is usually tapped by hand dug well. the major limitation of this aquifer is that, it is prone to poll ution because it is near to the ground surface. unlike the lower coastal plain sand (lcps) aquifer, it is tapped through boreholes. materials and methods fifty-eight samples including 45 hand dug wells (samples 1–45) and 13 boreholes (samples 46–58) were randomly selected for evaluation of groundwater salinization and quality assessment in the study area. samples were collected in clean 150ml polyethylene bottles and preserved in ice chests for delivery to the chemistry department of the university of lagos, akoka for laboratory analyses using standard methods (apha, 1998). in-situ parameters were measured for electrical conductivity (ec), ph and total dissolved solids (tds) using a portable hand held (hi98303, hanna model), (ph-102, rohs model) and tds/temp hm digital model respectively. the insitu measurements were necessary because these parameters are likely to change on transit to the labor atory. chloride, calcium, carbonate and bicarbonate were determined using titrimetry method. atomic absorption spectrophotometer (aas) hi 98180 model was used to analyze magnesium, potassium and sodium, and sulfate was determined using spectrophotometer, hach dr/2000 model. the individual sample co-ordinate and the computed revelle and water quality indices were exported to the surfer 6.0 software package for mapping the spatial variations of bicarbonate, the revelle index and the water quality index using the kriging method. the statistical analysis of the examined groundwater parameters were computed using spss software 17.0 version. evaluation of groundwater quality using water quality indices in parts of lagos-nigeria 31 co-ordinates of the sampled wells were recorded using global positioning system (gps) and thereafter were plotted using arcmap 9.3 software on the geological map of lagos, sheet 68 on 1:250,000 scale to generate a map of the sampling locations (fig.1). evaluation of groundwater salinity and the drinking water quality assessment were executed applying: revelle index (ri): r = rcl / (rhco3 – + rco3 2– ) (1) where: r = milliequivalents per litre (meq/l) ri < 0.5 (unaffected), 0.56.6 (slightly affected) > 6.6 (strongly affected) (zaharin et al., 2009; revelle, 1941) the water quality index (wqi) was evaluated using the world health organization (2004) standard. the stages of calculating the wqi include: qn = 100 [vn – vio ] / [sn – vn] (2) where: n is the water quality parameter and quality rating or sub index (qn) corresponding to n th parameter (i.e a number reflecting the relative value of this parameter with respect to its standard (maximum permissible value) qn = quality rating for the n th water quality parameter vn = estimated value of the n th parameter at a given the sampling point sn = standard permissible value of the n th parameter vio =ideal value of n th parameter in pure water (i.e. 0 for all other parameters except ph and dissolved oxygen (7.0 and 14.6 mg/l respectively). the unit weight (wn) is calculated by a value inversely proportional to the recommended standard value (sn) of the corresponding parameter. wn = k/sn (3) where: wn= unit weight for the n th parameters sn = standard value for the n th parameters k = constant for proportionality the overall wqi is calculated by aggregating the quality rating with the overall wqi which is calculated by aggregating the quality rating with the unit weight linearly as: wqi=ʃqnwn/ʃwn (4) results and discussion the measured parameters and the descriptive statistics of the groundwater characteristics of the study area are shown in table 1. the ph of the sampled wells varied from 3.4 to 8.55 indicating an extremely acidic to strongly alkaline condition that may affect the taste (todd and mays, 2005). fig.1 sampling locations 32 akoteyon (2013) table 1 detected parameters of groundwater and their descriptive statistics sample no. ph ec (µs/cm) tds (mg/l) na + (mg/l) k + (mg/l) ca 2+ (mg/l) mg 2+ (mg/l) cl (mg/l) hco3 (mg/l) so4 2 (mg/l) co3 2 (mg/l) 1 6.84 630 424 13.4 4.16 69 45 38 176 9 153 2 7.33 285 200 10.11 2.05 96 30 40 169 7 148.4 3 6.8 380 264 7.61 1.54 160 16 38 udl 11 445.2 4 5.96 748 515 13.65 2.28 316 26 82 50.4 17 339.2 5 5.92 204 141 3.7 0.45 86 30 18 udl 5 339.2 6 6.02 375 257 6.95 1.8 72 44 34 udl 9 275.6 7 6.52 222 153 6.33 2.12 90 22 20 udl 5 254.4 8 6.4 182 128 3.85 0.74 102 15 14 67.2 4 148.4 9 4.54 206 143 4.27 1.89 82 74 80 udl 6 314.4 10 5.58 763 533 32.3 5.12 110 112 176 udl 19 826.8 11 6.01 310 219 7.22 3.51 12 2 36 100.8 8 127.2 12 5.31 348 240 6.99 4.2 64 56 48 udl 8 402.8 13 5.48 174 124 4.16 1.89 30 26 32 117.8 5 84.8 14 5.5 360 250 5.59 2.34 150 20 44 369.6 8 106 15 5.32 40 30 0.63 0.19 16 2 8 udl 2 106 16 3.79 659 453 16.52 4.88 234 22 142 udl 14 360 17 3.4 213 150 2.79 0.87 92 16 30 udl 5 233.2 18 6.09 658 440 29.64 4.52 190 32 116 udl 8 848 19 6.86 327 223 9.2 1.76 94 28 36 252 6 63.6 20 6.61 145 99 4.09 0.36 44 16 16 50.4 4 84.8 21 6.57 4040 6112 1080.1 52.32 1200 580 3400 184.8 1250 106 22 6.7 442 302 17.89 2.72 52 74 70 67.2 7 275.6 23 7.14 648 449 25.56 3.97 114 96 100 621.6 12 127.2 24 6.41 490 341 15.89 2.71 76 94 62 218.4 7 190.8 25 6.8 738 492 69.7 10.58 118 106 246 210 10 udl 26 6.43 438 296 47.38 6.42 50 34 166 110 8 udl 27 5.48 648 442 41.53 5.65 138 54 140 120 9 udl 28 6.29 1575 1020 122.51 15.75 414 106 448 570 16 40 29 6.1 1053 705 112.42 14.63 328 86 374 456 14 26 30 6.67 806 537 104 16.3 406 92 356 380 12 38.5 31 5.48 318 202 5.27 3.12 138 26 40 104 8 29.7 32 5.89 369 242 3.4 2.42 140 24 16 86 6 udl 33 6.03 611 400 32.69 4.78 142 74 114 140 9 udl 34 6.39 790 541 38.24 5.17 184 16 130 240 12 udl 35 5.34 425 290 22.6 4.15 144 8 75 128 4 udl 36 5.61 490 305 10.46 5.2 100 12 114 104 6 udl 37 6.5 472 296 31.88 4.58 108 26 120 70 9 udl 38 5.09 68 47 1.3 0.5 12 2 8 udl 2 84 39 6.03 191 125 9.8 1.35 22 6 6 udl 2 96 40 6.3 115 81 6.2 0.17 14 4 10 udl 4 42 41 6.22 63 44 2.6 0.48 38 12 32 udl 4 48.4 42 8.55 103 72 3.6 4.8 60 10 46 udl 8 28 43 5.9 676 479 52.7 8.12 202 26 176 130 10 udl 44 5.64 201 134 24.6 6.18 196 48 166 146 10 udl 45 8 116 59 4.31 0.28 46 udl 16 0.08 4 udl 46 6.2 312 240 5.21 2.7 88 34 20 30.4 5 276.4 47 6.02 289 154 6.53 1.9 76 38 26 26.4 4 344.8 48 6 403 301 8.35 3.5 81 42 31 28 6 398.2 49 6.8 175 137.5 8 2.15 6.4 2.3 17.1 149.05 11.7 udl 50 7.1 210 147.4 26.3 12.25 22 10 11 48.23 5.4 udl 51 5.9 185 132.8 20.2 10.5 3.1 1.1 25.8 43.4 12.3 udl 52 6 70 23 30 5.2 udl udl 23 31.2 45 udl 53 6 72 22 30 4.8 udl udl 25 30 43 udl 54 6 70 23 31 4 udl udl 22 33.1 44 udl 55 5.4 66 66.9 2.2 1.2 2.1 0.77 11.6 29.5 1.2 udl 56 5.3 50 46.9 2.2 1 2.1 0.77 8.4 29.15 0.2 udl 57 5.4 66 66.9 2 1.6 2.1 0.77 11.6 25.2 0.6 udl 58 6 52 23 1.3 udl 24 udl 5 udl 1 udl udl-under detection limit. evaluation of groundwater quality using water quality indices in parts of lagos-nigeria 33 the electrical conductivity (ec) varied between 40 and 4,040μscm -1 with a mean value of 433.36µscm -1 . according to the classification in rao et al. (2012), samples from locations 1 to 20, 22 to 27 and 29 to 58 are of low enrichment of salts while location 21 and 28 depict medium and high enrichment of salts respectively. tds varied between 22 and 6,112 mg/l with a mean value of 351.44mg/l. according to todd and mays (2005), the samples from locations 1 to 20, 22 to 27 and 29 to 58 are of the fresh water type while locations 21 and 28 depict the brackish water type. calcium, magnesium, sodium and potassium varied between under the detection limit to 1, 200, under detection limit to 580, 0.63 to 1,080.10 and under detection limit to 52.32 mg/l with a mean value of 118.24, 41.03, 38.77 and 4.82 mg/l, respectively (table 1). carbonate, chloride, bicarbonate and sulfate varied between under the detection limit and 848, under the detection limit to 621.6, 5 and 3,400 and 0.2 to 1,250mg/l with mean values of 134.70, 133.04, 102.46 and 30.73 mg/l respectively. according to stuyfzand (1989), the classification of chloride shows that about 46.6% of cl in the samples accounts for fresh water while 37.9%, 8.6%, 5.2%, and 1.7% accounted for oligohaline, fresh-brackish, brackish and brackish-salt respectively (table 2). the spatial variation of bicarbonate in the study area is presented in (fig. 2). according to the who (2004) classification, the variation in hco 3 concentration revealed that about 31% of the samples are under poor zone, 29.3% moderate zone and 10.3% good zone respectively. evaluation of groundwater salinization the computed revelle index varied from 0.05 and 14.62meq/l. the relationship between the ratios of cl/hco3 + co3 indicates a strong positive linear relation with cl concentrations (r = 0.94, p < 0.01). this linear relationship indicates the mixing of saline water and fresh groundwater (zaharin et al., 2009). figure 3 shows the spatial variation of the extent of the groundwater salinization in the study area. about 56.9% of the samples (n = 33) were unaffected by salinity, 41.4% (n = 24) were slightly influenced and the remaining 1.7% (n = 1) was strongly influenced by salinity. areas of critical concern include locations 21, 25-30, 33-37, 41-44, and 51-58 in the study area. thus, effort must be made to curtail the current groundwater salinization in the area in order to ensure groundwater sustainability. assessment of drinking water quality the suitability of groundwater quality for drinking purpose in the study area was determined using world health organization (who, 2004) guidelines. according to sahu and sikdar (2008), the computed water quality index (wqi) ranged from 15.27 to 550.97mg/l. the spatial variations in the samples revealed that about 37.9% of the sampled wells had excellent water quality and 48.3%, 12.1% and 1.7% indicate good, poor and water unfit for drinking respectively (fig.4). critical areas that require urgent attention include locations 9-10, 16-17, 21 and 28. others are 12, 23, 25 27, 33 and 43-44. these locations pose a threat to human health and water resources management in the study area. table 1 (cont.) detected parameters of groundwater and their descriptive statistics ph ec (µs/cm) tds (mg/l) na + (mg/l) k + (mg/l) ca 2+ (mg/l) mg 2+ (mg/l) cl (mg/l) hco3 (mg/l) so4 2 (mg/l) co3 2 (mg/l) min 3.40 40.00 22.00 0.60 udl udl udl 5.00 udl 0.20 udl max 8.60 4040.00 6112.00 1080.10 52.30 1200.00 580.00 3400.00 621.60 1250.00 848.00 mean 6.07 433.36 351.40 38.80 4.80 118.24 41.03 133.04 102.50 30.70 134.70 std. dev 0.80 563.66 794.12 141.60 7.38 172.73 78.67 446.28 139.20 163.20 187.71 skewness -0.27 4.88 6.93 7.23 4.99 4.63 5.86 7.13 2.11 7.58 2.08 who std. 8.5 1000 500 200 10 75 30 200 300 200 300 min-minimum, max-maximum, std. dev-standard deviation; who-world health organization; std-standard table 2 classification of chloride in the study area (source: stuyfzand (1989)) chloride type chloride (mg/l) sample numbers very oligohaline < 5 oligohaline 30.0-150 (n=23) 5, 7–8, 15, 17, 20, 32, 38–40, 45–47, 49–58 fresh 30-150 (n=26) 1–4, 6, 9, 11–14,16, 18, 19, 22–24, 27, 31, 33–37, 41–42, 48 fresh-brackish 150-300 (n=5) 10, 25–26, 43–44 brackish 300-1,000 (n=3) 28–30 brackish-salt 1,000-10,000 (n=1) 21 salt 10,000-20,000 hypersaline >20,000 34 akoteyon (2013) 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good <100 mg/l poor 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good 100-250 mg/l moderate 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good >250 mg/l good fig.2 spatial variation of bicarbonate 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 373839 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <0.5meq/lunaffected 0.5-6.6meq/l slightly affected >6.6meq/lstrongly affected 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good <0.5 meq/l unaffected 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good 0.5-6.6 meq/l – slightly affected 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <100mg/l poor 100-250 moderate >250 -good >6.6 meq/l – strongly affected fig.3 spatial variation of revelle index 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking <50 excellent 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking 50-100 good 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking 100-200 poor 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking 200-300 very poor 3.4 3.5 3.5 3.6 3.6 3.7 6.4 6.5 6.5 6.6 12 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 212223 24 25 26 27 2829 3031 32 33 343536 37 38 39 40 4142 43 44 45 4647 48 49 5051 525354 5556 57 58 <50 -excellent 50-100 good 100-200 poor 200-300 very poor > 300 water unfit for drinking >300 water unfit for drinking fig.4 spatial variation of water quality index evaluation of groundwater quality using water quality indices in parts of lagos-nigeria 35 conclusion groundwater is increasingly gaining significance as the main solution to the water supply problems in nigeria, especially in the sub-urban and rural areas. the ph indicates extremely acidic to strongly alkaline conditions. about 96.6% of the ec values are characterized by low enrichment of salts, 12.1% medium enrichment of salts, and 1.7% high enrichment of salts. major cations are in the order of: ca 2+ > mg 2+ > na + > k + and the major anions are in the order of: co3 2 > cl > hco3 > so4 2. 46.6% of the samples accounts for fresh water and 37.9%, 8.6%, 5.2%, and 1.7% accounts for oligohaline, fresh-brackish, brackish and brackish-salt based on chloride. similarly, the classification of bicarbonate show that 31% of the samples fall under poor zone, 29.3% moderate zone and 10.3% good zone. groundwater salinization shows that 56.9% of the samples are unaffected, 41.4% are slightly influenced and 1.7% of groundwater was strongly affected. this infers that fresh groundwater contamination by salinity is a major concern for the fresh water supply in the study area especially around locations 21, 25-30, 33-37, 41-44 and 51-58. thus, the need for the regulating groundwater exploitation through monitoring by concerned agencies for sustainable groundwater resource management. the suitability of groundwater for drinking purpose shows that about 37.9% of the samples had excellent water quality and 48.3%, 12.1% and 1.7% indicate good, poor and water unfit for drinking respectively. it is deduced that locations around 9-10, 16-17, 21 and 28 pose a great threat to water quality in the study area. however, the study concluded that the water quality of the study area is of good quality, since about 86.2% is suitable for drinking 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water quality. first addendum, (3rd ed.) 1, 491–493. yidana,s.m and yidana, a . 2010. assessing water quality using water quality index and multivariate analysis environ earth sci 59, 1461–1473. doi: 10.1007/s12665009-0132-3. zaharin, a.a., abdullah, m.h., praveena, s.m. 2009. evolution of groundwater chemistry in the shallow aquifer of a small tropical island in sabah, malaysia. sains malaysiana 38(6), 805–812. http://www.ncbi.nlm.nih.gov/pubmed?term=rao%20ns%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=rao%20ps%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=reddy%20gv%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=nagamani%20m%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=vidyasagar%20g%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=vidyasagar%20g%5bauthor%5d&cauthor=true&cauthor_uid=21931947 http://www.ncbi.nlm.nih.gov/pubmed?term=satyanarayana%20nl%5bauthor%5d&cauthor=true&cauthor_uid=21931947 detection of plastic greenhouses using high resolution rgb remote sensing data and convolution neural network journal of environmental geography 14 (1–2), 38–46. doi: 10.2478/jengeo-2021-0004 issn 2060-467x detection of plastic greenhouses using high resolution rgb remote sensing data and convolutional neural network balázs jakab1*, boudewijn van leeuwen1, zalán tobak1 1department of geoinformatics, physical and environmental geography, university of szeged, egyetem u. 2-6, 6722 szeged, hungary *corresponding author, email: jakabbalazs501@gmail.com research article, received 5 february 2021, accepted 13 april 2021 abstract agricultural production in greenhouses shows a rapid growth in many parts of the world. this form of intensive farming requires a large amount of water and fertilizers, and can have a severe impact on the environment. the number of greenhouses and their location is important for applications like spatial planning, environmental protection, agricultural statistics and taxation. therefore, with this study we aim to develop a methodology to detect plastic greenhouses in remote sensing data using machine learning algorithms. this research presents the results of the use of a convolutional neural network for automatic object detection of plastic greenhouses in high resolution remotely sensed data within a gis environment with a graphical interface to advanced algorithms. the convolutional neural network is trained with manually digitized greenhouses and rgb images downloaded from google earth. the arcgis pro geographic information system provides access to many of the most advanced python-based machine learning environments like keras – tensorflow, pytorch, fastai and scikit-learn. these libraries can be accessed via a graphical interface within the gis environment. our research evaluated the results of training and inference of three different convolutional neural networks. experiments were executed with many settings for the backbone models and hyperparameters. the performance of the three models in terms of detection accuracy and time required for training was compared. the model based on the vgg_11 backbone model (with dropout) resulted in an average accuracy of 79.2% with a relatively short training time of 90 minutes, the much more complex densenet121 model was trained in 16.5 hours and showed a result of 79.1%, while the resnet18 based model showed an average accuracy of 83.1% with a training time of 3.5 hours. keywords: plastic greenhouse, deep learning, convolutional neural network, satellite image, google earth introduction in recent years, agricultural production in greenhouses showed a rapid growth (agüera and liu, 2009; wu et al., 2016; nemmaoui et al., 2019). in many arid and semiarid countries, plastic greenhouses form a large share in the total number of greenhouses, since they are more affordable and can be used temporary as well. plastic greenhouses are made of a partly transparent plastic cover to be able to control the environmental and growing conditions inside the greenhouse. it is important to monitor their spatial distribution, since this form of intensive farming requires large amounts of water and fertilizers and can have a severe impact on the environment. estimation of the share of plastic greenhouses in the total agricultural activities can be performed by directly counting the number of greenhouses. this is slow, labor intensive and consequently expensive, therefore, it makes sense to apply remote sensing data-based algorithms to detect them. apart from spatial planning and environmental protection, another reason to acquire knowledge of the number and location of greenhouses is that their registration is obligatory for taxation purposes. research on the classification of plastic or glass greenhouses using very high to medium resolution (multi-spectral) remote sensing data and methodologies has been published earlier. wu et al. (2016) applied random forest (rf) and support vector machine (svm) on medium resolution multispectral data. also, yang et al. (2017) used medium resolution data, but they presented an index-based approach resulting in an overall accuracy of 91%. koc-san (2013) reported high accuracies of classification of glass and plastic greenhouses using maximum likelihood (ml), rf and svm methods based on worldview-2 very highresolution data. agüera et al. (2008) received promising results when applying texture analysis combined with ml on very high-resolution satellite imagery. agüera and liu (2009) used ml classification to automatically delineate greenhouses. they report results with medium accuracy. supervised classification based on a combination of orthophotos and landsat data was proposed by gonzález-yebra et al. (2018). novelli et al. (2016) used a combination of landsat and sentinel-2. they classified medium resolution data using object based image analysis (obia) and rf. accuracies ranged between 89 and 93%. very high-resolution satellite imagery was used by nemmaoui et al. (2019) to derive surface and terrain models to extract plastic greenhouses. they report very high accuracies of up to 98%. most recently, yang et al. (2021) published a file:///e:/tanszek/joeg/edit/2021/1_2/04_jakab_et_al/jakabbalazs501@gmail.com jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. 39 manual approach to identify greenhouses to study urban fringe based on imagery downloaded from google earth. the term artificial intelligence (ai) was first used in 1955 (mccarthy et al., 1955). given that intelligence is difficult to define, this term is not easy to define either. it can be formulated as a process that mimics human abilities and behavior according to pre-programmed rules (nilsson, 1980; simon, 1995). machine learning (ml) is a part of artificial intelligence that, based on collected data, can learn and develop itself in an iterative way using pre-programmed rules (michie, 1968). artificial neural networks (ann) are a type of ml algorithms loosely based on the biological functioning of the brain. artificial neurons process and transmit many input signals to a large number of neighboring neurons. the neurons are stored in layers, the final layer collects the signals and processes them to an output signal, with is the result of the network. the network learns from input and output data pairs and stores their combined relationship as weights (müller et al., 1995). deep learning is a group of ml algorithms that uses anns with many hidden layers. the more hidden layers, the deeper and more complex the neural network and the more complicated tasks it can potentially solve. in the present age, deep learning has become widespread and makes it possible to process large data sets that are otherwise often too big to manage. examples of applications of deep learning include face recognition, image recognition, or self-driving vehicles (goodfellow et al., 2016). the current revolution in deep learning algorithms for computer vision also provides opportunities to improve analysis of remote sensing data. numerous studies have been published on the classification of medium (e.g., watanabe et al., 2018; gallwey et al., 2020; rai et al., 2020; virnodkar et al. 2020) and high resolution (e.g. flood et al., 2019; schiefer et al., 2020; zhang et al., 2020) satellite images using deep learning methods (kattenborn et al., 2021). detection of individual objects in the imagery is not as common as classification but has been published as well (ding et al., 2018; jiang et al., 2019; guo et al., 2020; pi et al., 2020). the difference between the two results is important; classification provides a label for every pixel, specifying the class it belongs to. this is the most common approach when converting remote sensing data to thematic maps. on the contrary, object detection provides an output layer on top of the original remote sensing image where the objects of interest are shown with a square bounding box around them indicating their precise location and accuracy estimation. the aim of our research is to evaluate if the current innovations in machine learning based technologies can be applied to detect plastic greenhouses. the presented methodology is based on object detection using a convolutional neural network (cnn). a cnn is an ann that is designed to learn the spatial features, e.g. edges, corners, textures, or more abstract shapes, that best describes the target class or quantity. like other anns, cnns are based on neurons that are organized in layers and are connected through weights and biases. the initial layer is the input layer, e.g. remote sensing data, and the last layer is the predicted output (kattenborn et al., 2021). in recent years, accessibility to machine learning algorithms and deep learning models in particular has been improved by implementations in user-friendly environments under python or r. a next step in the development towards easier excess to the algorithms is the implementation of graphical user interfaces on top of the functionality. one implementation is the deep learning toolset in arcgis pro (esri, 2021) which implements third-party deep learning frameworks – such as keras – tensorflow (abadi et al., 2015; chollet, 2015), pytorch (paszke et al., 2019), fastai (howard and gugger, 2020) and scikit-learn (pedregosa et al., 2011). in this study, we present a methodology based on freely available images and a convolutional network to detect plastic greenhouses in an area in the south of hungary. the area is mainly agricultural with a large amount of tunnel shaped plastic greenhouses. the earlier mentioned studies applied deep learning techniques for classification of high resolution remote sensing data, but none of them used cnn for object detection based on data from google earth. study area a 230 km2 area in the south east of the great hungarian plain, near the town of szeged (fig. 1) has been selected to test the cnn algorithm. the area is mainly agricultural and has a large number of greenhouses. other main land use/land cover classes in the area are forest, urban/build up and some water bodies. most of the area has chernozem and sandy soils, but in some areas arenosol can be found. the sandy soils absorb water quickly causing the soil to dry out and reduce its fertility. the area suffers from high air pollution and dust content. in the 1750s, locust tree (robinia pseudoacacia) was introduced in the region as an ornamental plant. the invasive species spread quickly through the region, and helps to reduce wind erosion, but it also reduces the nutrients in the soil. with 400-450 mm, the annual rainfall is low compared to the mean precipitation (600-700 mm) of the country (mezősi, 2011). data and methods the imagery used as input data for the presented detection algorithm was extracted from google earth. the highresolution data is a georeferenced red-green-blue (rgb) image collected by cnes/airbus in august 2020. the image was downloaded using the tile+ extension in qgis. the concept of convolutional neural networks was introduced in the 1980s by yann lecun (lecun et al., 1990). cnns differ from fully connected anns by having each neuron being connected to only a limited number of neurons in the previous layer. cnns assume that the input is an image and look for features through a kernel. the detection is performed through convolution between the input and the kernel thus the term convolutional neural networks. the kernels form a 40 jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. fig. 1 location of the study area convolutional filter, and a set of stacked convolutional filters makes a convolutional layer (fig. 2). convolutional layers are followed by activation functions which introduce nonlinear behavior to the model. each convolutional layer extracts features with increasing complexity from the input layer. after each convolutional layer, a pooling layer extracts the most prominent features and reduces the resolution of the previous input. a cnn thus contains a stack of convolutional layers followed by activation functions and pooling layers, and finally an addition of one or more fully connected (fc) layers. fc layers form an ann head on top of the cnn that is used to classify the cnn output into a set of finite classes (davies, 2018). in case of object detection, objects are not only classified, but their locations are indicated with bounding boxes as well (liu et al., 2016). the methodology to detect plastic greenhouses can be separated in 6 sequential steps. the first step is to download of the input image. the second is the generation of training and validation samples and the creation of image chips, and the third is the creation of the model architecture. the next step is the training of the model based on the training data. then, the model parameters are fine-tuned based on the validation data set. the sixth and final step is the inference of the trained model with the total image. the detection of greenhouses requires very high resolution data with at least 3 layers. this type of data can be provided by drones, aerial photographs or very high resolution satellite images. since it is the aim of our research to apply the methodology on a large area, images collected by drones are not an option. google earth provides a source of high-resolution aerial photographs and satellite images that can be downloaded for free for non-commercial use. therefore, an rgb image was downloaded from google earth with a resolution of 2000 dpi. this resulted in a 1 gigabyte three layer tif file with an approximate spatial resolution of 50 cm. selection criteria for the image were cloud cover percentage, spatial resolution and number of greenhouses. the extracted image covers an area of 230 km2. during the second step, samples of plastic greenhouses were identified in multiple subsets of the image. in each subset, all greenhouses were digitized manually to make sure that the model would not be trained with pixels that belong to greenhouses, but that were labeled as non-greenhouse pixels. in total, 2352 greenhouse samples were created. the higher the spatial resolution of the image, the easier is the identification of individual greenhouses; the downloaded image was of sufficient spatial resolution. the selection of the samples is of decisive important for the result of the detection of greenhouses. using rotation, it is possible to perform data augmentation, with is the artificial creation of more training samples by capturing the sample created by the user at multiple angles. the samples were used to generate training data in the pascal visual object classes meta data format (everingham et al., 2010) and serve as input for the process of sub-setting the total image into individual chips. only chips with (a part of) at least one sample in it were stored. with each chip an .xml file is produced that stores the location of the sample within the chip. the training data was used as input for the training phase, where the algorithm aims to detect the fig. 2 classification using a convolution neural network jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. 41 greenhouses. during object detection, the algorithm uses bounding boxes to delimit the objects’ location. the purpose of the training is to minimize the difference between the real and the modeled bounding boxes. in case there are several different objects in the image, all possible positions and box sizes need to be evaluated, which is calculation intensive. for this reason, originally, the r-cnn method was developed, which provides region suggestions. single-shot detectors are an improved detection algorithm and are designed to skip making region suggestions and solve classification and regression tasks in one step, making them more efficient and faster. the two best known algorithms are yolo (you look only once) and ssd (single shot detector) (liu et al., 2016). the latter is used this research, because it is the most accurate and fastest (poirson et al., 2016). training performance can be increased considerably by applying transfer training based on a model with many parameters that was pre-trained for a different task (howard and gugger, 2020). a large number of pre-trained models can be downloaded via the internet. each model has its specific architecture, among others they differ in number of layers and filter sizes. they can also vary in the type of data that was used to train them. the selection of the backbone model determines the architecture of the model used for the training. many experiments were carried out to determine the best backbone model. in the presented research, we evaluated the resnet18, densnet121 and vvg_11 models for training and inference. the learning rate is an important parameter during this phase. it determines the size of the adaptation of the weights during one pass of the training data through the network. if the learning rate is too low, the optimal solution for the model may not be found, if it is too high the model may take too long to converge, and training will never end. the best learning rate can be found manually, but in arcgis pro, it is possible to use fast.ai’s learning rate finder, which suggests an optimal learning rate. the maximum number of epochs is used to specify the maximum number of times the training data is used to adapt the weights of the network and therefore limits the training time. the batch size is a hyperparameter that defines the number of samples to work through before updating the model parameters. other parameters are the number of grids cell in which the image is divided, and the size and ratio parameters for the detection boxes. once the model and hyperparameters were determined, they were stored and used for inference on the image of the complete area. during the inference, parameters for the confidence threshold and non maximum suppression (nms) need to be determined. the confidence threshold is the minimum confidence that is required for an object to be stored. for example, in our research a setting of 0.5 was used, which means that the algorithm must be at least 50% confidence that it has found a plastic greenhouse. objects with a lower confidence are ignored for further processing. the output of the inference gives many overlapping boxes with different confidences. the nms parameters is used to remove overlapping boxes of the same objects and to determine how much overlap is allowed between adjacent boxes. the plastic greenhouses in the study area are located close to each other, therefore a 40% overlap setting was used in this research. each step of the workflow to detect plastic greenhouses was performed using the deep learning toolset of arcgis pro 2.7. the separate tools for the creation of samples, export of image chips, and the training and inference of the model provide a userfriendly interface to the complex algorithms that are used to detect the objects (esri, 2021). to be able to use the toolset, an arcgis pro license is required, and an opensource deep learning environment based on python implementations of well-known machine learning libraries like keras – tensorflow, pytorch, fastai and scikit-learn needs to be installed. although, it is possible to train the models using a cpu, it is highly recommended to use a gpu. results and discussion for the training in total 2352 plastic greenhouses were digitized with an average size of 200 m2. these were used to create 6228 partly overlapping image chips. each image chip had a size of 256 x 256 pixels and the average number of greenhouses per chip was 5. examples of image chips are shown in figure 3. many settings of the hyperparameters for the training were tested, and the optimum combination was reached with 50 iterations, a batch size of 8, grid values of 4, 2, and 1, zoom values of 0.7, 1.0, 1.3 and [1,1], [1, 0.5], [0.5, 1] for the ratio values. the learning rate was set to automatic, and 20% of the data was used for model validation. during the training phase, numerous experiments have been executed to determine the architecture of the model and the values of the hyperparameters. all training and inference tests were executed on a pc with and intel core i5, 8th generation processor, 8 gb ram and a geforce gtx 1050 graphics card. first, backbone models resnet18, resnet34, resnet50 and densenet121 were tested as architectures for the training. a subset of the result of the training with the resnet18 backbone model is shown in figure 4. obviously, the larger the model, the longer the time required for training. in our case, it took 16h 31m to train the large densenet121 model, while the resnet18 model with the same parameters took only 3h 24m. fig. 3 image chips with multiple samples of plastic greenhouses 42 jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. fig. 4 training results of model with resnet18 backbone, at the left the input sample is shown, while the right image shows the detected result the main problem with the larger backbone models was overfitting, therefore more samples were added to the training set by data augmentation, where the original training samples were rotated with 45° and 180° angles. densenet121, with 121 layers was finally trained with 6228 chips but did not provide better detection. this model gave the highest training accuracy of 79.1%. also, the resnet18 model was trained with the same sample set, acquired by data augmentation. the resnet18 training with 50 iterations and a batch size of 8 and resulted in an average accuracy of 80.1%. figure 5 shows the training and validation loss and clearly proves that the model is converging to an optimal solution. in the first test, the vgg_11 backbone model was evaluated for the training. this model has only 11 layers and is therefore much faster to train. the training and validation loss plot is shown in figure 6. the training took 90 minutes and the maximum number of epochs was set to 25, the number of samples was 5168. to prevent overfitting of the vgg_11 model, different settings for dropout were tested. dropout is a regularization method where randomly a part of the output of a layer is ignored and not read into the next layer. a value of 0.3 (30% of the data is ignored) gave the best result (fig. 7). the results of inference shown here are all executed on the same smaller test area. the main consideration for the selection of the area was that there are many plastic greenhouses that were not included in the training data set, so that it is possible to assess the quality of the inference. additionally, it was important to select as many different types of greenhouses as possible (different in size, color and damage) to be able to evaluate the capabilities of the models to detect all plastic greenhouses. figure 8 shows the inference results of the vgg_11 model. the model successfully found the large majority of objects of interest. the red symbols indicate the 222 greenhouses that the model detected. some objects were detected by this model, that are not a plastic greenhouse. these are indicated in black in figure 8. for example, the model also recognized large tents that are very similar in shape to greenhouses. the average accuracy of the bounding boxes detected during the inference using vgg_11 in the test area is 79.2%. the next backbone model used for inference was densenet121 (fig. 9). the model showed a slight over fitting in the initial trials, but adaptation of the hyper parameters and enlarging the training set showed that the model can detect greenhouses successfully. as a result of the inference using the densenet121 model, 230 plastic greenhouses were found in the test area. comparing with the results of the vgg_11 model, it can be observed that the inference made with the densenet121 model is more accurate. densenet121 did not erroneously detected the large tents as plastic greenhouse unlike vgg_11 model (yellow circles in fig. 9). the densenet121 model yielded an average of 79.1% for the accuracy value. fig. 5 training and validation loss using the resnet18 backbone and 2352 samples fig. 6 training and validation loss using the vgg_11 backbone fig. 7 training and validation loss using the vgg_11 with dropout 0.3 jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. 43 finally, the results of the resnet18 model are presented in figure 10. during the first training, a higher learning rate of 0.03 was used, but this did not give satisfying results. then, the training was performed with the learning rate finder, suggesting far lower rates that provided a much better result. for the presented inference, the resnet18 model trained with the suggested learning rates was used. the manual learning rate setting resulted in a worse result, giving an average accuracy value of 78.3% and the model placed 225 bounding boxes during detection. the most accurate result was achieved by the resnet18, with the optimal learning rate. it gave an average accuracy of 83.1% for the detected 232 bounding boxes. improvement over the densenet121 result is indicated in yellow. fig. 8 detection of plastic greenhouses on the test area using vgg_11 fig. 9 detection of plastic greenhouses on the test area using densenet121 44 jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. arcgis pro provides a user-friendly environment to sophisticated deep learning algorithms. the dialogs hide the complexity of working with machine learning algorithms from the user, but to use the functionality optimally, it is required to have detailed knowledge of the hidden algorithms. this also helps to make efficient decisions on the many options that need to be specified during the creation of the training data, the training and the inference. erroneous settings of the hyperparameters during training can easily result in models that never reach an optimal solution. the selection of the backbone model is of decisive importance for the cnn processing. the complexity of the model, combined with setting for the learning rate, batch size and maximum number of epochs determine the accuracy of the results and the time required to train the model. often, it might be more efficient to allow a slightly lower accuracy over much better performance. the size and quality of the training data is another important condition for successful use of the deep learning functionality. data augmentation is a powerful procedure to generate more training data without digitizing more examples. it also reduces the chance of overfitting, since more and different types of examples that may occur in other areas, are shown to the model. detection of objects in remotely sensed images provides a different result than the classification results that are common in remote sensing studies. for this reason, it is difficult to compare the results of traditional classifications and object detection as presented in our research. traditional classifications provide one class label for each pixel in the image, while object detection aims to detect all objects of interest and their locations in the image. the metrics used for the estimation of the accuracy are also different since the location of an object is not an output of classification algorithms. in the presented research, rgb channel images downloaded from google earth are used as input data. the limited number of channels is a disadvantage compared to other data sets, when the data would be used for traditional classification. the models used as backbone for the convolutional neural network model are trained with three channel data though and are therefore particularly suitable as input data. conclusion the presented research explores the possibilities for detection of plastic greenhouses in an agricultural area in the south east of hungary using freely available high resolution satellite imagery and a convolutional neural network. the aim was to use state of the art deep learning techniques without the need to go into the depths of writing code, therefore we used the recent arcgis pro deep learning implementation. this user friendly environment allows to experiment with many setting for creation of the training data, the backbone model, the training, and the inference. it also provides feedback to the user on the success of the training. the connection between the deep learning algorithms and the gis functionality of the software makes it easy to perform all steps in the detection of greenhouses in a spatial environment and display the results as maps and images. the results of the inference show that with careful selection of the network architecture and hyper parameters it is possible to achieve high accuracy output maps. the calculation intensive experimentation fig. 10 detection of plastic greenhouses on the test area using resnet18 jakab et al. 2021 / journal of environmental geography 14 (1–2), 38–46. 45 requires a high-performance computer. the use of 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hydrological events on a tisza river basin pilot area, hungary dávid béla vizi1*, jános fehér2, attila lovas1, sándor kovács1 1middle tisza district water directorate, boldog sándor istván körút 4, h-5000 szolnok, hungary 2global water partnership central and eastern europe, gwp cee regional secretariat (shmu) jeseniova 17, 833 15 bratislava, slovakia *corresponding author, e-mail: vizi.david.bela@kotivizig.hu research article, received 30 september 2018, accepted 1 november 2018 abstract climate change takes more and more challenges to the water management. future predictions show that the possibility of extreme floods and drought events are increasing, thus an additional task of the water management can be the fulfilment of the increasing water demands. these new extreme hydrological situations need to be properly handled in water management. the paper presents the first modelling results of the jointisza project carried out on a selected sub -basin of the tisza river, which is endangered by hydrological extremes. our aim was to demonstrate the applicability of a one -dimensional hydrodynamic model to study the effects of the climate change. future hydrological trends were introduced in the river basin and it was assessed how the results of climate models can be used for further hydrodynamic modelling. to address challenges of climate change and supply the stakeholders with an adequate amount of water, proper operation of the reservoir and the irrigation canals are needed. the use of hydrological modelling can be helpful to adequately distribute water resources. keywords: water quantity, drought, flood, hydrodynamic modelling, water demand, climate scenarios introduction the tisza river basin (trb) can be considered unique in several aspects among the river basins of europe. in certain hydrometeorological situations, the chance of extraordinary floods is high. this was especially true at the beginning of the 2000s, when the flood waves set new record high water levels along the hungarian section of the tisza river (szlávik, 2005). over the last decades, drought has also taken more and more challenges to the experts of the local water directorates. the occasional extreme low water flow of the river is a problem especially in the flat areas of the tisza river basin. the climate change plays a major role in the emergence of these hydrometeorological situations (lehner et al., 2006). regarding spatial and temporal distribution of drought in europe, the major european droughts also impacted hungary. hungary has a high risk of developing a drought period, especially typical in the great hungarian plain region (tamás, 2016). the drought phenomenon can significantly increase because of the antropogenic activity and ineffective water management. it is expected that the extremely long, dry weather conditions will occur more regularly for years in hungary (szalai, 2009). the prevalence of the droughts has increased over the past decades, and especially the rolling drought phenomena have become critical when consecutive years of drought multiply the adverse effects of previous years (pálfai, 1992). regarding to the final report of the danube river basin climate adaptation study from mauser et al. (2018) the possibility of more intense and more harmful droughts are expected in the middle tisza region.the water demand is also expected to increase in the great hungarian plain which causes new challenges in water management (somlyódy, 2011). the local water directorate is responsible to provide adequate amount of water ( nws, 2017) to satisfy the water needs. this requires river basin planning, and proper water management. in the jointisza project a pilot area was selected in the middle tisza which is endangered by both extreme situations, such as floods and droughts. our main goal was to investigat e the impacts of climate change induced drought and flood issues on a smaller region within the trb. this paper introduces the first modelling results which are the possible impacts of a long-lasting period with water scarcity in this pilot area. we applied the forecasts of climate models produced by the joint research centre. the data sets they generated – according to the predicted hydrological, meteorological, economic, and social conditions – were used in modelling as a boundary condition (bisselink et al., 2018). with the help of these time-series, we aimed to explore possible medium and long-term conflict situations in water resources and to make recommendations for possible measures, thereby helping the water management planning of river basins with similar problems. 58 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. pilot area characteristics of the pilot area the selected pilot area is located in the flat region of the trb in the middle of the hungarian great plain (fig. 1). the pilot area gets water from the lake tisza, which water intake is controlled by the local water directorate. this pilot area is selected because only a proper water management work could satisfy the water demands. the size of the pilot area is 2884.6 km2. it is bordered by the tisza river from the west, and by the lake tisza from the north. the eastern border is the hortobágy-berettyó river and the tiszafüredi main irrigation canal, and the southern border of the area is the hármas-körös river. the area is characterized by a very low elevation (79-100 mbf). in the tisza sub-basin the lofty sedimentary rocks dominates in the top 10 m caprock formations. most of the soils are typically well-productive, so a significant part of the pilot area is suitable for agricultural activity. the typical genetic soil type in the region is the chernozem. large areas are covered with meadow and alluvial soils, which are common in the floodplains. the proportion of alkaline soils is exceptionally high in the hortobágy-berettyó region. the size of the agricultural land is the largest in hungary in the tisza sub-basin, but from agroecological point of view this land use is considered to be the most unfavourable structure. large area is arable land and they have low proportion of intensive cultures (vegetables, fruits). a significant part of the agricultural area consists of arable land (73 %), while the share of the garden, fruit and grapes represent less than 0.5%. the peculiarities of this river basin are the relative importance of fish ponds. the proportion of forest areas does not reach 5%. hungary's water network is basically determined by the fact that the country is located in the middle of the carpathian basin. in the country, about three-quarter of the water resources is transported by the danube and the drava rivers, while almost only a quarter of the available water resources is transported by the tisza river. the tisza is the second most significant river in hungary. the tisza’s full gradient is 30 m (5 cm/km) in hungary. the minimum measured water flow was 56 m3/s, and the maximum measured value was 2950 m3/s at kisköre. the average flow value is 507 m3/s at this tisza river section. the lake tisza is the biggest artificial surface water in hungary. the lake was artificially created when the kisköre barrage was constructed. the lake is operated as a reservoir, so it has two different operating water levels for summer and winter seasons. the summer water level usually lasts from the middle of march to the end of october, and it is 88.57±0.05 m. the surface of the lake tisza is 127 km2, with a volume of 253 million cubic meters; more than 130 million m3 can be utilized. lake tisza can be considered as a multipurpose water management facility; its main utilizations are: water supply, hydropower (at the kisköre barrage), fishing and nature. fig. 1 location of the selected pilot area located in the tisza river basin, hungary vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. 59 the area has a dry continental climate, and it has the driest climate in hungary. the annual average temperature is between 10-11°c, and the monthly average temperature in july is around 21°c. the mean annual temperature fluctuation is 23.0-24.5°c. the annual amount of sunshine hours in the hungarian great plain is over 2000 hours. based on the measured data of the middle tisza district water directorate, the annual precipitation is about 520 mm in this area, which is the lowest annual average precipitation in the country. the territorial and temporal distribution of the precipitation is also extreme. the annual rainfall also varies within wide limits. some years (e.g. the year of 2010 when the annual precipitation was 820 mm) had a lot of precipitation and it caused floods and inland excess waters. in the last some decades that even in the same year after a wet period a dry and warm period occurred with heavy drought. climate change can play a major role in the emergence of extreme conditions. future predictions suggest that even more extreme drought periods may also occur more and more often (mauser et al., 2018). because of these extreme situations a well performed and appropriate water resource management planning and regulations are important. the pilot study intended to contribute to a better planning process that takes into account the climate change induced impacts on surface water quantity. the pilot area has some particular characters that were taken into account when it was selected. the required amount of water by the stakeholders in the pilot area can be ensured only by the proper water management of the district water directorate (nws, 2017). the water demand is satisfied by a dense canal network of the area from the tisza river. in a dry period, the lake tisza can provide sufficient water for the region, but the water flow is exclusively managed by district water directorate into the pilot area. the special features described above have determined which model type could fit most to assist the water quantity management. nagykunsági irrigation system the most significant irrigation system of the pilot area is the nagykunsági irrigation system. based on the water usage data of the middle tisza district water directorate, the annual volume of water supply of the area is around 15-20 million m3 on average, but can reach 25 million m3 in a drier period. the main irrigation canal in the irrigation system is the nagykunság main canal. this canal gets water from the lake tisza through a water intake structure controlled by the local water directorate and passes the water to the hármas-körös and the hortobágy-berettyó rivers. the water inflow is around 20-35 m3/s in irrigation season (from april to september). the canal is split into two branches near örményes. the overall length of the main canal is 74.5 km (including the western branch). the eastern branch of the canal is 18.07 km long. the nagykunsági main irrigation canal flow out from the 403.000 fluvial km section of the tisza and reaches the hármas-körös river at the 35.600 fluvial km section. the eastern branch of the nagykunsági main irrigation canal flow out from the nagykunsági main canal, reaches the hortobágyberettyó river at the 16.630 fluvial km section. the water from the nagykunsági main irrigation canal is distributed to various irrigation sections to reach the user (fig. 2). the most important irrigation sections of the nagykunsági irrigation system are the following: nk iii, nk iv, nk v-1, nk v-2, nk vii-1, nk x, nk xii. figure 2 shows the main parts of these irrigation sections; the water can be drained to the other part of the pilot area. the irrigation canals have several hydraulic structures to properly drain the water through the nagykunsági irrigation system. the nagykunsági main irrigation canal has 7 inline structure (fig. 2). the main aim of these structures to ensure water retention, and to provide proper water distribution. fig. 2 irrigation sections of the nagykunsági irrigation system methods one dimensional hydrodynamic model hec-ras is capable of performing one-dimensional water surface profile calculations for steady varied flow in natural or constructed channels. it is the basic equation and numerical model of free-surface, onedimensional, continuously variable non-permanent water movement. the most important conditions are: one dimensionality, graduality, free-surface, and nonpermanent character. of these, the first two are the hardest to follow; these are the most important constraints. in our case, when we model a nonpermanent hydraulic phenomenon in a complex cross60 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. section of a meandering watercourse network, the validity of these conditions has a decisive influence on usability (us army corps of engineers, 2016). in its current structure, the database of the model includes the 600 km long river section between tiszabecs and szeged from the tisza. the model also contains the canals of the pilot area. the total length of streams involved into calculations exceeds 2 000 km. we installed 102 bridges and 19 inline structures into the model. the model contains the nagykunsági irrigation canal, which is the most important irrigation canal of the pilot area. the complete hydrodynamic model includes the following river sections (fig. 3):  tisza, from tiszabecs to szeged (600 km),  szamos, from csenger to outfall (50 km),  kraszna, from ágerdőmajor to outfall (45 km),  bodrog, from felsőberecki to outfall (50 km),  hernád, from gesztely to outfall (23 km),  sajó, from felsőzsolca to outfall (50 km),  zagyva, from jásztelek to outfall (55 km),  berettyó, from pocsaj to outfall (68 km),  sebes-körös, from körösszakál to körösladány (54 km),  fehér-körös, from gyula to outfall (9 km),  fekete-körös, from ant to remete (16 km),  hármas-körös, from gyoma to outfall (90 km),  hortobágy-berettyó, from ágota to outfall (80 km),  nagykunsági irrigation canal (with the eastern and western branches), from abádszalók to mezőtúr/öcsöd (110 km). we have advanced the stream system of the model by more than 2 000 cross sections. the cross sections are the basis of the one-dimensional models. the calibration and the roughness coefficient are only party compensate the possible inaccuracies of the cross-sections. the model stability is greatly improving if the cross sections are as dense as possible. based on previous modelling experiences, the optimal distance between cross sections from model point of view is 400 800 m for the tisza, and 200 400 m for the tributaries of the tisza. for the irrigation canals, the optimal distance is 200 400 m. the hydrodynamic model has 14 upstream, and 1 downstream boundary condition. the boundary conditions of the rivers are located on the hungarian border sections. we have chosen these points to minimize the impact of the boundary conditions on modelling results in the pilot area. at each point there are flow data available for input data. the applied hec-ras model gives detailed description of the entire river system and provides an opportunity for taking into consideration the hydraulic engineering structures, as well as bridges, barrages, culverts, overflow weirs, floodgates, bottom stages, bottom sills, side overflows and gates, static reservoirs, pump head stations and water intakes (us army corps of engineers, 2016). the model includes 102 bridges, and 16 inland structures, and it also contains water intakes. we took into the model every irrigation section of the nagykunsági irrigation system as a point like water intakes. the model also contains every directly water use along the nagykunsági main irrigation canal, so water consumption can be tested as a simple drainage. we used fig. 3 the layout and the boundary conditions of the model vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. 61 the possible water demand values for input data which are based on the survey of the hungarian chamber of agriculture (nws, 2017). for calculation of the water discharge capacity of the main river bed of tisza as well as for taking the flood plain vegetation into consideration we used the roughness (smoothness) factors given in the table 1 in the course of calibration of the model. we determined the vegetation on the flood plain by aerial photographs, i.e. by orthophotographs, as well as by the results of on-site inspections. the roughness factor was changed crosswise according to flood plain vegetation. the roughness (smoothness) factor assigned to these was determined on the base of the prescriptions of the hungarian standard, as well as on the base of values applied also by hec-ras and proposed by chow (1959). table 1 roughness / smoothness coefficients no. type n (s/m 1/3) k (m1/3/s) min max min max 0 river/canal channel 0.060 0.017 16.67 58.8 1 pasture 0.050 0.025 20.00 40.0 2 plough-land 0.050 0.020 20.00 50.0 3 sparse shrub 0.080 0.035 12.5 28.6 4 dense shrub 0.160 0.040 6.25 25.0 5 forest without undergrowth 0.120 0.030 8.33 33.3 6 forest with undergrowth 0.200 0.080 5.00 12.5 the calibration of the model was accomplished gradually, starting with the shorter sections. we assembled together the individual section and then performed the river sections. the calibration of tisza and its tributaries was made for the low-water period of the year 2012. on the river section between tiszabecs and szeged, the difference between the calculated water level and the observed was between 0 and 10 cm in absolute values, which can be considered as a very good result. the pilot area’s canal network calibrated separately. we used data from the year of 2013 to calibrate the irrigation canals. the difference between the calculated water level, and that of observed was between 0 and 10 cm, like the river network. after the calibration was made, the separate water streams were connected. climate scenarios of the joint research centre the joint research centre (jrc) studied the effects of changing climate, land use, and water demand on water resources in the danube river basin using climate induced runoff modelling technique (bisselink et al., 2018). the water resources calculations were done with the lisflood 2.0 model which is a gis-based spatially-distributed hydrological rainfall-runoffrouting model (de roo et al., 2000, van der knijff et al., 2010; burek et al., 2013). as a result of the runoff modelling, water flow data were made available for our work for the rivers of the tisza river basin. in the jrc analysis, 11 different european eurocordex climate scenarios have been used (table 2). the coordinated downscaling experiment over europe (euro-cordex, jacob et al. 2014) is an international climate downscaling initiative that aims to provide high-resolution climate projections up to 2100 (bisselink et al., 2018). flow time-series were made available for our work for every boundary condition calculated from the jrc runoff model. time-series were from 2011 to 2099 for each 11 climate projections. in addition to the boundary table 2 euro-cordex climate projections (bisselink et al., 2018) no. climate scenario institute global climate model reg. climate model exceeding 2°c warming 1 clmcom-cclm4-8-17_bc_cnrm-cerfacscnrm-cm5_rcp85 clmcom cnrm-cm5 cclm4-8-17 2044 2 clmcom-cclm4-8-17_bc_ichec-ecearth_rcp85 clmcom ec-earth cclm4-8-17 2041 3 clmcom-cclm4-8-17_bc_mpi-m-mpi-esmlr_rcp85 clmcom mpi-esm-lr cclm4-8-17 2044 4 dmi-hirham5-ichec-ec-earth_bc_rcp85 dmi ec-earth hirham5 2043 5 ipsl-ineris-wrf331f_bc_rcp85 ipsl ipsl-cm5a-mr ineris-wrf331f 2035 6 knmi-racmo22e-ichec-ecearth_bc_rcp85 knmi ec-earth racmo22e 2042 7 smhi-rca4_bc_cnrm-cerfacs-cnrmcm5_rcp85 smhi cnrm-cm5 rca4 2035 8 smhi-rca4_bc_ichec-ec-earth_rcp85 smhi ec-earth rca4 2041 9 smhi-rca4_bc_ipsl-ipsl-cm5a-mr_rcp85 smhi ipsl-cm5a-mr rca4 2044 10 smhi-rca4_bc_mohc-hadgem2-es_rcp85 smhi hadgem2-es rca4 2030 11 smhi-rca4_bc_mpi-m-mpi-esm-lr_rcp85 smhi mpi-esm-lr rca4 2044 62 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. conditions, discharge data were also available for an internal river section of the tisza, which was the inflow section of the river into lake tisza. this point was an important control point in the middle tisza from water management point of view. using the data of this control section it was possible to examine how much water flows into the lake tisza from the tisza river. if the flow of this river section decreases below 105 m3/s water shortage can be considered, and when discharge falls below 60 m3/s, water restrictions may be needed (mtdwd, 2013). results hydrological changes of the middle tisza analysis has been made for the 11 flow time-series which refers to the inflow section of lake tisza, which can be used to quantify future trends in the middle tisza hydrology. in the months of september and october will have the highest probability when the flow will decrease below 60 m3/s at the river section near tiszafüred. the return time for extreme low-water periods is 3-4 years in all 11 climate projections. based on the data released by the jrc, the occurrence of more and more long-lasting lowwater periods are also predicted for the second half of the century. the most extreme "smhi-rca4_bc_ichecec-earth_rcp85" run occurred a 128-day period below 60 m3/s. with a 24.5 m3/s minimum discharge. in addition to the extreme low-water conditions, some climate scenarios have also generated extraordinary flood waves. in the case of two projections (clmcomcclm4-8-17_bc_cnrm-cerfacs-cnrm-cm5_ rcp85, ipsl-ineris-wrf331f_bc_rcp85), the maximum flow is above 4500 m3/s, which would pose a serious flood risk to the middle tisza in the future, with special regard to the kisköre barrage. it is based on the analysis to define which climate scenario should be used as the boundary condition of the hydrodynamic model. according to the analysis, the “smhi-rca4_bc_ichec-ec-earth_rcp85” is selected to study low-water periods. water demand changes of the study area it was necessary to determine the future water demand of the pilot area for the study of water resources. the hungarian chamber of agriculture conducted a nationwide water demand survey (gwdm, 2018). based on the survey it can be stated that the water demand is well above the amount of water currently used in hungary. the annual water demand of the pilot area exceeds 55 million m3, which is expected to increase in the future. 80 % of this value refers to the nagykunsági irrigation system. it can be stated, that the nagykunsági irrigation system satisfies the large part of the water needs. part of the water demand can be assured directly from the nagykunsági main irrigation canal, and the other parts of water needs are distributed through the irrigation sections (fig. 4). these water demands have become the part of the hydraulic model as water abstractions. according to the survey, there are 6474 locations for water uses. 3914 are new request for using water from this number. these new demands account 23 million m3 quantity of water in a year, almost half of the total annual water needs in the pilot area. results of the hydraulic modelling the modelling scenario is a long-lasting low-water period, whereby the water flow to the area is lower than the sum of water flowing to the tail-water at kisköre barrage and of into the irrigation canals from the lake tisza. the boundary conditions are selected based on the statistical analysis of the water flow datasets produced by the jrc. in this scenario, there are several periods with water scarcity. the year of 2085 of the time series includes an extreme low-water period, which data sets of the year have been used as the boundary conditions of the model at every upstream river sections. at the river section of the tisza near tiszafüred, for more than 3 months, the flow of the river is below 105 m3, which is a period with water scarcity.the boundary condition of the model for the tisza is shown in figure 5. fig.4 the distribution of future water demand in the nagykunsági irrigation system 8.14 3.14 16.84 0.83 0.73 1.11 5.29 2.81 4.87 0 5 10 15 20 main + western branch eastern branch nk iii. nk iv. nk v-1. nk v-2. nk vii-1. nk x. nk xii. million m3 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. 63 in the modelling scenario when the river's flow falls below 100 m3/s the water level of the lake tisza gradually began to decrease. the trend continues for two months when the discharge at the upper section of the river increase above 100 m 3/s. during the critical period, the amount of water which is drained from the lake tisza to the nagykunsági main irrigation canal is continuously ensured and corresponding to the water demands (fig. 6). we studied how quickly the stored water of lake tisza would be consumed. figure 7 shows the development of water flow and water level at kisköre barrage in the modelled year. in the first half of the year there is enough water flow to the river to maintain the operating water level (88.67 ± 0.05 m) of the reservoir. then in the summer months, the river flow gradually decreases until it reaches the critical 60 m3/s value. this low water condition lasts for one and a half months when the water level of the reservoir is reduced by 2.96 m. this level of water is reducing in order to meet the water demands in the pilot area without any problems and to e nsure the minimum 60 m3/s to the kisköre barrage tail-water. this minimum flow of water is needed in addition to the ecological goals, it is also necessary for the water supply of szolnok. in addition to provide sufficient quantity of water at the river section downstream of kisköre, enough water is also drained into the irrigation canals. in the middle tisza there is a water restraint plan which determines the cases when the amount of water taking from the lake tisza to the irrigation canals should be limited. according to the regulations 14.4 m3/s flowrate must be secured from the eastern branch of nagykunsági main irrigation canal to the hortobágy-berettyó, as well as 1,6 m3/s from the western branch of nagykunsági main irrigation canal to the hármas-körös (mtdwd, 2013). the main goal with these minimum flows is fig. 5 boundary condition of the hydrodynamic model for the tisza river in the modelling scenario fig. 6 discharge and stage at the inlet point of the nagykunsági main irrigation canal 0 50 100 150 200 250 300 350 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 1 0 1 1 1 1 1 2 1 1 3 1 1 4 1 1 5 1 1 6 1 1 7 1 1 8 1 1 9 1 2 0 1 2 1 1 2 2 1 2 3 1 2 4 1 2 5 1 2 6 1 2 7 1 2 8 1 2 9 1 3 0 1 3 1 1 3 2 1 3 3 1 3 4 1 3 5 1 3 6 1 d is c h a rg e [ m 3 /s ] time [day] 83.5 84 84.5 85 85.5 86 86.5 87 87.5 88 88.5 0 5 10 15 20 25 30 35 40 1 2 5 1 5 0 1 7 5 1 1 0 0 1 1 2 5 1 1 5 0 1 1 7 5 1 2 0 0 1 2 2 5 1 2 5 0 1 2 7 5 1 3 0 0 1 3 2 5 1 3 5 0 1 3 7 5 1 4 0 0 1 4 2 5 1 4 5 0 1 4 7 5 1 5 0 0 1 5 2 5 1 5 5 0 1 5 7 5 1 6 0 0 1 6 2 5 1 6 5 0 1 6 7 5 1 7 0 0 1 7 2 5 1 7 5 0 1 7 7 5 1 8 0 0 1 8 2 5 1 8 5 0 1 d is c h a rg e [ m 3 /s ] time [hour]discharge stage s ta g e [ m ] 64 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. to provide water for the körös valley. however, when the discharge of the tisza falls to a critical level (below 60 m3/s), the amount of water passed through the nagykunsági main irrigation canal may need to be reduced. in the first scenario of modelling, this regulation was not considered. in the model scenario the minimum flowrate was guaranteed at the outflow sections of the nagykunsági main irrigation canal. figure 8 shows the development of the water flow and stage at the outflow section of the western branch. 1.62 m3/s is the minimum flow during the summer period, which is almost the same as the value in the operating rule. figure 9 shows the development of water flow and water level at outflow section of the eastern branch of the nagykunsági main irrigation canal in the modelled year. the time series shows that the water flow is between wide limits during the entire irrigation period. this is caused by the operation order of the inline structure at the outflow section. the gate is set to maintain a certain water level at the headwater, which is 84.55±0.05 m. the average discharge is 14.9 m3/s during the irrigation period. the results of the model show what is happening with the water resources of the lake tisza in an extreme low-water situation. the model runs show that the lake tisza is able to supply the area with water during a period with water scarcity, but in extreme cases the water level may become critically low. the water restrictions are not in the model scenario and it was assumed that the water level of lake tisza would not reach critically low level. these steps were not included in this model version because the main goal was to investigate at what condition the pilot area can be supplied with enough water. fig. 7 discharge and stage at the headwater of kisköre barrage fig. 8 discharge and stage at the outflow section of the nagykunsági main irrigation canal (with the western branch) 84 84.5 85 85.5 86 86.5 87 87.5 88 88.5 89 0 100 200 300 400 500 600 700 800 900 1 2 5 1 5 0 1 7 5 1 1 0 0 1 1 2 5 1 1 5 0 1 1 7 5 1 2 0 0 1 2 2 5 1 2 5 0 1 2 7 5 1 3 0 0 1 3 2 5 1 3 5 0 1 3 7 5 1 4 0 0 1 4 2 5 1 4 5 0 1 4 7 5 1 5 0 0 1 5 2 5 1 5 5 0 1 5 7 5 1 6 0 0 1 6 2 5 1 6 5 0 1 6 7 5 1 7 0 0 1 7 2 5 1 7 5 0 1 7 7 5 1 8 0 0 1 8 2 5 1 8 5 0 1 8 7 5 1 d is c h a rg e [ m 3 /s ] time [hour]discharge stage s ta g e [ m ] 84 84.2 84.4 84.6 84.8 85 85.2 85.4 85.6 0 0.5 1 1.5 2 2.5 3 1 2 5 1 5 0 1 7 5 1 1 0 0 1 1 2 5 1 1 5 0 1 1 7 5 1 2 0 0 1 2 2 5 1 2 5 0 1 2 7 5 1 3 0 0 1 3 2 5 1 3 5 0 1 3 7 5 1 4 0 0 1 4 2 5 1 4 5 0 1 4 7 5 1 5 0 0 1 5 2 5 1 5 5 0 1 5 7 5 1 6 0 0 1 6 2 5 1 6 5 0 1 6 7 5 1 7 0 0 1 7 2 5 1 7 5 0 1 7 7 5 1 8 0 0 1 8 2 5 1 8 5 0 1 d is c h a rg e [ m 3 /s ] time [hour]discharge stage s ta g e [ m ] vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. 65 conclusions the climate change can have serious impact on the selected pilot area, which pose also challenges to the water management of the area. lake tisza has the highest value among water resources in the middle tisza region, which can provide great help in overcoming these challenges. supplying the stakeholders with an adequate amount of water proper operation of the reservoir (lake tisza) and the irrigation canals are needed. it can be helpful to use hydrological modelling to distribute water resources in a proper way, which means that enough water has to be available. as demonstrated in the modelling results, the necessary water could be provided in the pilot area without the introduction of water restriction measures. in case of long-lasting drought period the water users of the area could have enough water, but in exchange that the water resources of the lake tisza would be reduced to a dangerous low level. this could cause serious ecological, economic and social conflict. based on the experiences of this model results, the further researches could include water restriction measures. it will also help to assess how the water level of the lake tisza can be maintained within the regulation range, while at the same time limiting the use of water in the area according to the water restriction plans in consensus with the stakeholders. acknowledgement the jointisza project is co-funded by the european union erdf and ipa funds focuses on interactions of two key aspects, the river basin management (rbm) and flood protection, taking into account the views of relevant stakeholders who have pivotal role in the tisza rbm planning process. references bisselink, b., bernhard, j., gelati, e., adamovic, m., jacobs, c., mentaschi, l., lavalle, c. and de roo, a., impact of a changing climate, land use, and water usage on water resources in the danube river basin, eur 29228 en, publications office of the european union, luxembourg, 2018, isbn 978-92-7985889-5, doi:10.2760/89828, jrc111817 burek, p., de roo, a.p.j., van der knijff, j.m, 2013. lisflood – distributed water balance and flood simulation model – revised user manual. joint research center, institute for environment and sustainability, european union. chow v.t. 1959. open-channel hydraulics, mcgraw-hill book co, 680 p, new york de roo, a.p.j., wesseling, c.g., van deursen, w.p.a. 2000. physically-based river basin modelling within a gis: the lisflood model. hydrological processes 14, 1981–1992. doi: 10.1002/1099-1085(20000815/30)14:11/12<1981::aidhyp49>3.3.co;2-6 gdwm (general directorate of water management), 2018. database of the national water demand survey (nemzeti öntözési igény felmérés adatbázisa). in hungarian. jacob, d., petersen, j., eggert, b., alias., christensen, o.b., bouwer, l.m., braun, a. et al. 2014. euro-cordex, reg environ change 14, 563–578. doi: 10.1007/s10113-013-0499-2 lehner, b., böll, p., alcamo, j., henrichs, t., kaspar, f. 2006. estimating the impact of global change on flood and drought risks in europe: a continental, integrated analysis. climatic change 75, 273–299. doi: 10.1007/s10584-006-6338-4 mauser, w., stolz, r., weber, m., ebner, m. 2018. danube river basin climate change adaptation – final report, germany. mtdwd (middle tisza district water directorate) 2013. water management strategy in the middle tisza. online available at: http://kotivizig.vizugy.hu/doksik/vizkeszletgazdalkodasi_strateg ia.pdf (in hungarian) middle tisza district water directorate (mtdwd), 2018. water restriction plan of the middle tisza district water directorate. in: kötivizig (ed.) kötivizig vízkorlátozási terve nws, 2017. national hungarian water strategy. general directorate of water management. online available at: http://www.kormany.hu/download/6/55/01000/nemzeti%20v %c3%adzstrat%c3%a9gia.pdf (in hungarian). pálfai, i. 1992. aszályok a tisza-völgyben. (droughts in the tisza valley). in: fejér l., kaján i., (ed.) mérlegen a tiszaszabályozás, mht-ovf, budapest, 33–40. somlyódy l. 2011. magyarország vízgazdálkodása: helyzetkép és stratégiai feladatok (water management of hungary: situation and strategic tasks), mta, budapest. online available at: http://old.mta.hu/data/strategiai_konyvek/viz/viz_net.pdf (in hungarian) fig. 9 discharge and stage at the outflow section of the nagykunsági main irrigation canal (with the eastern branch) 82 82.5 83 83.5 84 84.5 85 0 5 10 15 20 25 1 2 5 1 5 0 1 7 5 1 1 0 0 1 1 2 5 1 1 5 0 1 1 7 5 1 2 0 0 1 2 2 5 1 2 5 0 1 2 7 5 1 3 0 0 1 3 2 5 1 3 5 0 1 3 7 5 1 4 0 0 1 4 2 5 1 4 5 0 1 4 7 5 1 5 0 0 1 5 2 5 1 5 5 0 1 5 7 5 1 6 0 0 1 6 2 5 1 6 5 0 1 6 7 5 1 7 0 0 1 7 2 5 1 7 5 0 1 7 7 5 1 8 0 0 1 8 2 5 1 8 5 0 1 d is c h a rg e [ m 3 /s ] time [hour]discharge stage s ta g e [ m ] http://kotivizig.vizugy.hu/doksik/vizkeszletgazdalkodasi_strategia.pdf http://kotivizig.vizugy.hu/doksik/vizkeszletgazdalkodasi_strategia.pdf 66 vizi et al. 2018 / journal of environmental geography 11 (3–4), 57–66. szalai, s. 2009. drought tendencies in hungary and its impacts on the agricultural production. cereal research communications 37, 501–504. tamás j. 2016. kihívások az aszálykutatás területén. (challenges in drought research). hidrológiai közlöny 96 (2), 13–20. (in hungarian) us army corps of engineers, 2016. hec-ras river analysis system – user’s manual, usa. van der knijff, j.m., younis, j., de roo, a.p.j. 2010. lisflood: a gis-based distributed model for river-basin scale water balance and flood simulation. international journal of geographical information science 24(2), 189–212. doi: 10.1080/13658810802549154 introduction pilot area characteristics of the pilot area nagykunsági irrigation system methods one dimensional hydrodynamic model climate scenarios of the joint research centre results hydrological changes of the middle tisza water demand changes of the study area results of the hydraulic modelling conclusions acknowledgement references assessing the spatio-temporal pattern of land use and land cover changes in osun drainage basin, nigeria journal of environmental geography 12 (1–2), 41–50. doi: 10.2478/jengeo-2019-0005 issn 2060-467x assessing the spatio-temporal pattern of land use and land cover changes in osun drainage basin, nigeria eniola damilola ashaolu*, jacob funso olorunfemi, ifatokun paul ifabiyi department of geography and environmental management, faculty of social sciences, university of ilorin, pmb 1515 ilorin, nigeria *corresponding author, e-mail: damash007@yahoo.com research article, received 15 january 2019, accepted 2 april 2019 abstract over the years, osun drainage basin has witnessed tremendous increase in population, and urbanization that have changed the landscape of the area. this study evaluated the spatio-temporal pattern of land use/land cover change (lulc) in the study area, and made hydrological inferences. landsat imageries were acquired from usgs-eros satellite image database for the period 1984, 2000 and 2015, while the digital elevation model (dem) was obtained from shuttle radar topography mission (srtm) of the national aeronautics and space agency (nasa). supervised image classification using the maximum likelihood algorithm in erdas imagine was adopted to classified the land use/land cover of the study area into seven classes. elevation, aspect and slope of the study area were processed from dem using arcgis. modules for land use change evaluation (molusce) plugin in qgis was used to simulate the basin future lulc change, using change driving factors of population, elevation, aspect and slope of the study area. there was about 234% increase in built up areas and 89.22% in crop/shrubs between 1984 and 2015. the most significant decrease in lulc occurred in forest (58.75%) and wetland (84.69%) during this period. the predicted future lulc change suggests that only about 12% of the basin will remain under forest cover by the year 2046. the results underscored the increasing anthropogenic activities in the basin that influenced recharge rate, surface runoff, incidences of soil erosion, etc., in osun drainage basin. the planting of the lost native trees was recommended for the sustainability of the basin’s ecosystem. keywords: land use/land cover, spatio-temporal, change detection, osun drainage basin introduction the existing land use/land cover (lulc) in a region and the previous impacts of the earlier lulc change still operating in the system determines the response of the ecosystem to disruption in lulc (martin et al. 2011). the change in lulc of a region, particularly increase in built up areas advertently or inadvertently alters the hydrological processes which include change in runoff pattern, modification of peak flow characteristics, alteration of water quality, etc. (noorazuan et al., 2003). in fact, changes in land use may have unintended negative impacts on the hydrological regime of a drainage basin, thereby increasing the chances of flood occurrence and also reducing the dry season flow (lorup et al., 1998). studies have reported that change in land use and land cover can influence surface runoff, infiltration, groundwater recharge, water quality and supply in a drainage basin. depending on the degree of change, overland flow can be increased or reduced, infiltration and recharge can also increase or reduce (ziegler and giambelluca, 1997; turner et al., 2001; butt et al., 2015; ashaolu, 2018). in the views of ashraf (2013) and butt et al. (2015), land use/land cover change in a drainage basin include rapid urbanization, deforestation and afforestation which endlessly influence the water budget; and the type and magnitude of surface and subsurface water exchanges. thereby affecting drainage basin ecology and their various benefits to man. nevertheless, enhanced water preservation schemes can be articulated through the appropriate identification of the spatio-temporal variation taking place in a drainage basin and the relationship between the various components of the basin (ashraf, 2013; butt et al., 2015). therefore, assessing the spatio-temporal pattern and changes of land use and land cover at drainage basin level is essential to the management and planning of the drainage basin water resources (butt et al., 2015) and land use allocation that will not jeopardize the basin ecosystem in particular. over the years, osun drainage basin which is one of the two major drainage basins in the southwester n nigeria has witnessed tremendous increase in population, farm settlements, urbanization and emerging cities which have changed the landscape of the drainage basin. the land use pattern within osun drainage basin include land use for residential/settlements, built up areas, bare rocks, soils surfaces, farmlands (annual crops/shrubs and agroforestry/secondary regrowth), vegetation and water bodies. over two decades ago, salami (1995) reported that the increasing population density coupled with the long history of agricultural colonization of some parts of the basin has resulted to substantial alteration of the basin’s natural environment. salami et al. (1999) also reported that the natural vegetation of so many parts of the basin has been replaced by secondary forest or perennial and annual crops. 42 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. therefore, the vegetation of the area can be described as derived savannah characterized by gallery of forest along stream sides and tall grasses with scattered perennial trees over land. the basin is covered by secondary forest and the derived savannah mosaic predominates in the northern part. originally, almost all parts of the basin had a natural lowland tropical rain forest vegetation; but this has however, been replaced by secondary forest regrowth as a result of years of anthropogenic activities. however, relics of the old rainforest species are still found in some isolated areas. some of the reasons for this change in vegetation are fuel wood production, road construction, clay and sand quarrying and traditional farming practices (ifabiyi, 2005). in recent years, studies on lulc in osun drainage basin were carried out to understand the changing pattern of lulc in settlements therein and were for the purpose of urban planning (salami, 1995; salami et al., 1999; akinyemi, 2005; mengistu and salami, 2007; gasu et al., 2016) and not with the aim of understanding the implications of such lulc changes on the hydrology of the entire basins. these studies have suggested changes in lulc all over the basin which will no doubt influence the water budget. for example, akinyemi (2005) discovered that the greatest percentage change in land use/land cover of the part of the basin that includes, ilesha, ijebu ijesa, imesi ile, otan aiyegbaju, igbajo efon alaiye and oke-messi, etc. were recorded on built up areas/roads (88.41%), while agroforestry/secondary regrowth decreased by 49.06% between 1986 and 2002. similarly, gasu et al. (2016) discovered that the urban/built-up areas in osogbo, one of the major towns in the basin have increased by about 415% between 1986 and 2012. in addition, mengistu and salami (2007) reported a significant conversion of natural vegetation cover to farmland and settlements between 1986 and 2002 in the upper part of the basin. the area covered by savanna and high forest declined by 71.9 and 8%, respectively, while shrubs/farmlands and settlements/bare surface increased by 413.6% and 192.4%, respectively. all these studies attributed the change in the land use/land cover of the area to the rapid expansion of agricultural land as a result of change in socioeconomic system of the region, population growth, expansion of settlements, gold mining activities, fuelwood extraction, intensive biomass burning and illegal logging. it is noteworthy, that a study that attempted a lulc classification of osun drainage basin was limited to the upper part of the drainage basin basically in the portion that falls within osun and ekiti states (akinwumiju, 2015), and there is need to cover the entire drainage basin in order to fully understand the lulc change scenario in osun drainage basin, nigeria. the changes in lulc experienced in osun drainage basin over the years will no doubt influence the hydrology of the basin. therefore, understanding land use and land cover change in the basin will enhance planning and management activities within the study area. this study therefore evaluated the change in lulc of osun drainage basin over the years and made hydrological inferences from the results of the change detection. study area osun drainage basin is located between latitudes 6°25´58.79ʺ and 8°21´3.6ʺ n and longitudes 3°47´34.8ʺ and 5°10´55.2ʺ e in the southwestern nigeria (fig. 1). fig. 1 location and position of osun drainage basin, nigeria. source: modified form ashaolu (2016) ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. 43 river osun which is the major river in the drainage system accents in oke-mesi ridge, about 5 km north of effon alaiye and flows north across the itawure gap to latitude 7°53ʺ and then deviates westwards via osogbo, ede and southwards to flow into lagos lagoon (ogun-oshun river basin development authority (oorbda, 1982; oke et al., 2013; ashaolu, 2016). the basin climate is influenced by the movement of the inter-tropical convergence zone (itcz), the quazi-stationary boundary that distinguishes the subtropical continental air mass over the sahara and the equatorial maritime air mas over the atlantic ocean (oorbda, 1982). the climate of the basin can be described as the tropical continental climate of koppen aw type humid tropical rainforest climate (ifabiyi, 2005). the months of february and march are the hottest in the basin and temperatures are high over the entire basin during this period. the mean annual temperature is about 30°c, which can varies depending on the location and time of the year (ifabiyi, 2005). the basin is underlain by two types of rocks which are the basement complex rocks and the sedimentary basins (oorbda, 1982; oke et al., 2013). about 93% of the basin is underlain by the basement complex rocks, while the remaining 7% is sedimentary rock found in the southern part of the basin close to the atlantic (ashaolu, 2016). the soils in larger part of the study area belong to the highly ferruginous tropical red soils associated with basement complex rocks (ifabiyi, 2005). the relief of the basin is generally undulating and descends from an altitude of about 700 meters in oke lmesi area to 50 meters and below in areas around epe and ibeju lekki in the southern parts of the basin (ashaolu, 2016). the land use pattern within the drainage basin includes land use for residential/settlements and built up areas, bare rocks, bare surfaces, crops/shrubs, vegetation/forest and water bodies. the population distribution pattern of the basin is quite uneven. the urban population in the basin is larger than the rural population. based on the 1963 population census of western nigeria, the estimated population of the basin made by ogun-oshun river basin development authority in 1980 was 4,281,000 and was estimated to be 12,046,145 in 2015 from 1991 population census using 3.0 percent growth rate for areas that comprises of rural and urban settlements in nigeria (ashaolu, 2018). materials and methods landsat imageries of the study area were acquired from usgs-eros satellite image database for 3 epochs (1984, 2000 and 2015). table 1 shows the type, path/row, date and characteristics of the satellite images acquired. the images of the years 1984 and 2015 were captured in december, while that of the year 2000 were captured in february. the disparity in the months was because february year 2000 was the closest month to december with all the four satellite scenes that covered the study area. it is important to note that vegetal cover from december to march in the study area are quite similar, hence it cannot affect the reality of the change detection registered in this study. the satellite images of 2015 are pansharpened using the panchromatic 15m band of landsat 8 and all the other images were resampled into 15m pixel size from their original 30m resolution. the nearest neighbor resampling method was adopted to resample the satellite images using arcgis 10.4. the study area falls within four different satellite scenes. the bands of each of the satellite image scenes of the three periods were first stacked in erdas imagine 2014. the four scenes for the years 1984, 2000 and 2015 were mosaic using the mosaicpro algorithm in erdas imagine 2014. the resulting images were subset using the study area shapefile to bring out the satellite images of the area of interest (aoi). the aoi images were enhanced by filtering the imageries in erdas imagine, resampled and projected. the images were enhanced into natural colour composite to improve the visual interpretation. all the images were projected to universal transverse mercator projection of wgs84 coordinate system, zone 31n. table 1 satellite image characteristics sn image type path/row acquisition date resolution 1 landsat 8 oli/tirs 191/54 191/55 190/54 190/55 24/12/2015 24/12/2015 17/12/2015 17/12/2015 30 m 2 landsat 7 etm 191/54 191/55 190/54 190/55 06/02/2000 06/02/2000 15/02/2000 15/02/2000 30 m 3 landsat 5 tm 191/54 191/55 190/54 190/55 18/12/1984 18/12/1984 11/12/1984 11/12/1984 30 m the supervised classification method in erdas imagine 2014 was adopted, using the maximum likelihood algorithm. the coordinates of some identified features within the basin were recorded and used as training samples for supervised classification of the remotely sensed data. one hundred and forty distributed training sites depicting all the main land use/land cover classes were used in each of the landsat image used for the classification. the training sites (signatures) of all images were developed by using the spectral characteristics of known to train the classification algorithm for the land use/land cover mapping of the basin, which represent various land use/land cover of interest. after classification, ground truthing was carried out to verified doubtful areas in the classified image. the classified lulc classes were corrected using the recode option in erdas imagine. the accuracy assessment was conducted using 250 points, based on ground truth data and visual interpretation of the images. the 250 points were randomly selected in preparing confusion matrix for accuracy assessment, which is a popularly accepted method in determining the accuracy of lulc classification (foody 2002). the 1984 and 2000 landsat imageries could not be checked against the ground truth data point to validate the interpretation made. hence, google earth images for these two periods were adopted for references. tilahun and teferie 2015; and tadele et al. 2017 adopted similar approach in their studies with reasonable results. the randomly generated points in the classified 1984 and 2000 images were imported into google earth images of 31/12/ 1984 and 31/12/2000, respectively to verify the accuracy of the classifications. also, the randomly generated points in the classified 2015 image was imported into google earth image of 14/12/ 2015 to verify the accuracy of the classification 44 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. (tilahun and teferie, 2015; tadele et al., 2017) and the generated confusion matrix derived from the image and the points collected during ground truthing was also used for the accuracy assessment (ismail and jusoff, 2008).thereafter, the kappa coefficient and overall accuracy were calculated to assess the mapping accuracy of the lulc classification. seven land use/land cover classes reported in various part of the study area by akinyemi (2005), meginstu and salami (2007) and gasu et al. (2016) that include bare surfaces, built up area, crops/shrubs, forest, rock outcrops, water bodies and wetland were adopted as the basis for classification in this study. the land use/land cover maps of the basin for the period 1984, 2000 and 2015 were developed and measured for each land use/land cover types. a post classification detection approach was adopted for the change detection analysis. the change information was conducted using a pixel-based comparison, this enable us to interpret the changes overtime more effectively using the “-from, -to” information. the classified image of the three period were compared using cross-tabulation which assisted us to determine both qualitatively and quantitatively aspects of the changes for the year 1984 to 2000 to 2015. the change matrix (weng, 2001; rawat and kumar, 2015) was prepared using erdas imagine. therefore, the quantitative areal data of the total lulc changes, gains and losses in each lulc classes between the three period of investigation were compiled. modules for land use change evaluation (molusce) plugin in qgis was adopted in simulating the future lulc change in the basin. molusce is designed to analyze, model and simulate land use/cover changes and predict the future direction of change by using spatial change variables that include elevation, slope, aspects, distance to roads, population, etc. in this study, to simulate the future change in the drainage basin, the lulc change explanatory variables or change driving factors that include population, elevation, aspect and slope of the study area were adopted. the resulting predicted land use/land cover should be used with caution because there are other factors that can drive change in the future besides the factors adopted in this study. the digital elevation model (dem) of the study area was obtained from shuttle radar topography mission (srtm) of the national aeronautics and space agency (nasa). elevation, aspect and slope of the study area were processed from dem using arcgis 10.4. also, the 1991 population of the study area acquired from national population census in nigeria was projected using the 3.0 growth rate to get the population of the study area as at 2015. all these variables are ranked between 0 and 1 using the fuzzy membership tool in arcgis 10.4. the change transition matrix for the predicted 2046 lulc change was also computed. results and discussion land use/land cover classification, 1984-2015 the results of the seven (7) classified lulc for the study area are presented in table 2 and figure 2. in the base year, forest area constituted the most extensive type of land use/land cover of osun drainage basin. accordingly, it table 2 land use/land cover classification of osun drainage basin, 1984-2015 land use/land cover types 1984 2000 2015 area (km2) % area (km2) % area (km2) % 1 bare surfaces 2040.95 20.56 2709.57 27.30 3087.31 31.10 2 built up areas 317.64 3.20 459.18 4.63 1063.91 10.72 3 crops/shrubs 1646.14 16.58 4163.35 41.94 3114.86 31.38 4 forest 5223.61 52.62 2059.21 20.75 2154.87 21.71 5 rock outcrops 493.05 4.97 342.35 3.45 420.09 4.23 6 water bodies 50.76 0.51 61.64 0.62 61.59 0.62 7 wetland 154.07 1.55 130.93 1.32 23.59 0.24 total 9926.22 100.0 9926.22 100.00 9926.22 100.00 fig. 2 the classified images of osun drainage basin, 1984, 2000 and 2015 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. 45 accounted for about 52.62% of the total drainage basin area in 1984, followed by bare surface and crops/shrubs, occupying 20.56% and 16.58% of the total drainage area, respectively (table 2). about 0.51% of the study area was covered by the water bodies, which is the least of the seven (7) land use/land cover classified in 1984. in 2000, crops/shrubs, bare surfaces and forest covered 41.94%, 27.30% and 20.75%, respectively of the total basin area. also, bare surface, crops/shrubs, forest covered 31.10%, 31.8% and 21.71%, respectively, while built up area accounted for 10.72% of osun drainage area in 2015. for the lulc map of 1984, the kappa coefficient and overall accuracy were found to be 0.71 and 0.80, respectively. the kappa coefficient and overall accuracy were 0.80 and 0.85 for the year 2000 lulc map. also, the kappa coefficient and overall accuracy were found to be 0.79 and 0.82, respectively for the lulc map of 2015. land use/land cover change, 1984-2015 to explain the changes of one lulc class to another during the period of study, a change detection matrix was prepared and the results are presented in table 3. land use/land cover change, 1984-2000 between 1984 and 2000, bare surfaces, built up areas, crops/shrubs and water bodies gained a total land area of 668.62km2, 141.54km2, 2517.21km2 and 10.88km2, respectively. crops/shrubs has a remarkable increase of 152.92%. it was also observed that built up area increased with about 44.56% between 1984 and 2000. this can be attributed to the increasing human population within the basin. akinyemi (2005), mengistu and salami (2007) and gasu et al. (2016) similarly reported increases in settlements/built up areas in their studies in the different parts of the basin. this confirms the fact that there is an increasing trend in the size of built up areas in the osun drainage basin. the area covered by bare surfaces, built up areas, crops/shrubs and water bodies expanded at an annual average rate of 1.93%, 2.62%,9.00% and 1.26%, respectively between 1984 and 2000. in the same period, forest, rock outcrops and wetland lost a total land area of 3164.40km2, 150.70km2 and 23.15km2, respectively. the forest area decreased rapidly with a total loss of 60.58% of its initial areal coverage. the sharp decrease in the size of forest between 1984 and 2000, is due to anthropogenic activities. similar results were observed in some parts of the basin between 1986 and 2002 (akinyemi, 2005; mengistu and salami, 2007). the forest area, rock outcrops and wetland receded at an annual rate of 3.56%, 1.80% and 0.88%, respectively between 1984 and 2000. land use/land cover change, 2000-2015 built-up areas increased significantly during this period. it indeed increased by131.70% from its original size of 459.18 km2 in 2000 to 1064.91km2 in 2015 (table 3). this gives an average annual growth rate of 8.23%. a change largely due to increasing population and urbanization. as a matter of fact, the population of the basin that was put at 4,281,000 in 1980 by oorbda (1982) was estimated to be 12,046,145 in 2015 by ashaolu (2018). the increasing built-up areas can severely change the water balance of the study area, influence the rate of recharge and the microclimate of the area (lerner et al., 1990; jyrkama and sykes, 2006). also, the amount of direct groundwater recharge resulting from rainfall may reduce as a result of the increase in impervious surfaces from built up areas, while surface runoff will increase significantly (rose and peters, 2001). expectedly, crops/shrubs, water bodies and wetland receded at an annual rate of 1.57%, 0.08% and 5.12%, respectively. for example, crops/shrubs lost an area of 1048.50 km 2 , which is about 58% of its basin coverage in 2000. the study of akinyemi (2005) in a small section of the drainage basin, while agreeing with this finding continues up until 2015. land use/land cover change, 1984-2015 the greatest percentage change for the 32-year-period was recorded on built-up area with about 235% increase at an average annual rate of 7.34% (table 3). built-up area increased significantly from 317.64 km2 in 1984 to 1063.91km2 in 2015. the increasing areal extent of the builtup areas confirmed the results of early studies (akinyemi, 2005; mengistu and salami, 2007; gasu et al., 2016) in some parts of the study area. also, crops/shrubs gained about 89.22% with an average annual rate of 2.79%. crops/shrubs increased by an area of 1468.22km2, from table 3 area and amount of change in land use/land cover categories in osun drainage basin, 1984-2015. note: the signs + and indicate increase and decrease, respectively land use/land cover types 1984-2000 average rate of change (1984-2000) 2000-2015 average rate of change (2000-2015) 1984-2015 average rate of change (1984-2015) area (km2) % area (km2) % area (km2) % area (km2) % area (km2) % area (km2) % 1 bare surfaces 668.62 32.76 39.33 1.93 377.74 13.94 23.61 0.87 1046.36 51.27 32.70 1.60 2 built up areas 141.54 44.56 8.33 2.62 604.73 131.70 37.80 8.23 746.27 234.94 23.32 7.34 3 crops/shrubs 2517.21 152.92 148.07 9.00 -1048.50 -25.18 -65.53 -1.57 1468.72 89.22 45.90 2.79 4 forest -3164.40 -60.58 -186.14 -3.56 95.66 4.65 5.98 0.29 -3068.70 -58.75 -95.90 -1.84 5 rock outcrops -150.70 -30.57 -8.86 -1.80 77.74 22.71 4.86 1.42 -72.96 -14.80 -2.28 -0.46 6 water bodies 10.88 21.44 0.64 1.26 -0.05 -0.07 0.00 0.00 10.84 21.35 0.34 0.67 7 wetland -23.15 -15.02 -1.36 -0.88 -107.34 -81.98 -6.71 -5.12 -130.48 -84.69 -4.08 -2.65 46 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. 1646.16km2 in 1984 to 3114.86km2 in 2015. the increase recorded in the percentage area of crops/shrubs conform with the work of salami et al. (1999), which reported that natural vegetation has largely been replaced by perennial and annual crops in many parts of the basin. the changes in land use/land cover during the 32 years, especially increase in built up and crops/shrubs can be attributed to population growth and settlement expansion, these scenarios had culminated into conversion of natural vegetation to farmland. other human activities such as fuel wood extraction, sand mining, quarrying and gold mining etc. have all contributed to land use changes. the most notable decrease in lulc classes in the osun drainage basin was observed in the forest area and wetland. forest decreased from a total land area of 5223.61km2 (52.62%) in 1984 to 2154.87 km2 (21.71%) in 2015. this is similar to the study of hammad et al. (2018) in the southern syria coastal basin where forest area decreased from about 64% in 1987 to about 38% in 2017. the forest area receded at an annual average rate of 1.84% during the period under investigation. this can be attributed to the years of human occupation and interference with the tropical vegetation of the drainage basin. the long history of agricultural practices and increasing population density in the area would have resulted into substantial modification of the natural vegetation. wetland declined from a total land area of 154.07 km2 in 1984 to 23.59 km2in 2015. wetland area receded at an annual average rate of 4.08 km2 during this period. this is attributable to wetland being converted to built-up area as there is need for accommodation for the teeming population in the basin. figure 3 shows the percentage change in lulc in osun drainage basin between 1984 and 2015. this shows the areal extent’s increase or decrease by each lulc in percentages. fig. 3 percentage change in land use/land cover in osun drainage basin, 1984-2015 the socio-economic characteristics of the people in the study area has significantly influenced the changes in lulc observed. most communities in osun drainage basin earn their living through farming, logging and fuel wood production. the issue of climate change is another major cause of the disappearing natural vegetation in addition to the prevailing human activities. the sudanosahelian zone has been reported to be advancing southward of latitude 10°n resulting in loss of forest species and arable lands. all these are responsible for the rapidly changing land use and land cover in the osun drainage basin (fasona and omojola, 2005; mengistu and salami, 2007). the implications of the changing lulc include increasing incidences of soil erosion, increasing reservoir sedimentation, soil degradation and unfavourable changes in the hydrological regime. groundwater recharge is influenced by plant cover and land use practices. hence, the type and nature of land cover can have a significant influence on infiltration, and on groundwater recharge (jyrkama and sykes, 2006). altering the natural land surface as observed in this study will significantly alter the groundwater recharge (lerner et al. 1990; lerner 2002) of the drainage basin. the results of the change detection transition matrix between 1984 and 2015 (table 4) revealed that:  about 25% of the area that are bare surface in 1984 has been converted into built-up area, 4.55% are crops/shrubs, 5.06% are rock outcrops, while 65.43% remained unchanged;  about 32% of forest area in 1984 remained unchanged, while it lost 43.70% and 21.68% to crops/shrubs and bare surfaces, respectively;  rock outcrops lost 35.12% to bare surfaces, 13.46% to built-up areas and 12.40% of its areal extent to crops/shrubs;  no significant conversion of water bodies to other lulc class, as it maintained 89.35% of its size; and  about 66% of wetland was converted to bare surfaces. the forest area, bare surface and crops/shrubs lulc classes were the most significant land cover transitions during the period of investigation. hence, spatial analysis was performed on the three classes to evaluate the spatial texture of these changes during the periods 1984 to 2015 (fig. 4). predicted future land use/land cover change in osun drainage basin, 2046 based on the rate of change between 1984 and 2015, the predicted lulc change revealed that by 2046, bare surface will increase slightly by 188.01 km2 (table 5). thus, bare surface would have increased from 3087.31 km2 in 2015 to 3275.32 km2 in 2046. built-up area would have increased steadily from 1063.91 km2 in 2015 to 1658.85 km2 by 2046. this is 55.92% increase. the simulated result shows that the increase in built-up area are closely associated with the existing built-up areas. this will be more pronounced in the northwestern part of the study area, especially in the oyo state portion of the basin, in and around ogbomosho. the growth that will be experienced in this area is attributable to population 10.54 7.52 14.8 -30.91 -0.74 0.11 -1.31 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 c h a n g e i n a r e a ( % ) land use/land cover bare surfaces built up areas crops/shrubs forest rock outcrops water bodies wetland ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. 47 increase, that will lead to the expansion of built-up areas. also, crops/shrubs lulc class will increase slightly from 3114.86 km2 in 2015 to 3311.11 km2 by 2046, which is an increase of 6.30%. this suggest that farming activities in the basin will increase only slightly. there may be further increase, if the effort of the federal government of nigeria to diversify the economy is vigorously pursued. the future lulc change revealed that between 2015 and 2046, the forest area will continue to decrease. as much as 897.69 km2 of forest land may be lost to other uses between this period. thus, it is expected that forest area will decrease from 2154.86 km2 in 2015 to 1257.18 km2 by 2046. the 42% reduction in forest area, is worrisome because it reflects the unrelenting activities of wood loggers in the study area. continuous deforestation of the forest area will certainly have significant impacts on the water budget of the study area, especially groundwater recharge. based on this study, water bodies lulc will decrease by 2.70%. wetland which is one of the important groundwater recharge mechanisms in a table 4 land use/land cover change transition matrix in osun drainage basin (1984-2015). figures in the upper rows indicate areas of particular lulc type that remained unchanged (in bold) or converted to other lulc types in km2. figures in italics in the lower rows indicate areas of particular lulc type that remained unchanged (in bold) or converted to other lulc types in percentage land use/land cover categories land use/land cover 2015 (km2) bare surfaces built up areas crops/shrubs forest rock outcrops water bodies wetland total area l a n d u se /l a n d c o v e r 1 9 8 4 ( k m 2 ) bare surfaces 1333.54 65.43 493.53 24.8 92.93 4.55 15.31 0.75 103.37 5.06 0.80 0.04 1.48 0.07 2040.95 100 built up areas 3.50 1.10 309.96 97.58 3.25 1.02 0.00 0.00 0.70 0.22 0.06 0.02 0.17 0.05 317.64 100 crops/shrubs 343.56 20.87 108.61 6.60 667.99 40.58 437.51 26.58 81.89 4.97 6.42 0.39 0.16 0.01 1646.14 100 forest 1132.32 21.68 41.22 0.79 2282.96 43.70 1649.40 31.58 91.07 1.74 7.17 0.14 19.48 0.37 5223.61 100 rock outcrops 173.21 35.13 66.36 13.46 61.14 12.40 51.45 10.44 139.67 28.33 0.43 0.09 0.78 0.16 493.05 100 water bodies 0.06 0.12 0.56 1.10 3.84 7.56 0.03 0.07 0.12 0.23 45.35 89.35 0.80 1.57 50.76 100 wetland 101.12 65.63 43.68 28.35 2.76 1.79 1.16 0.75 3.28 2.13 1.35 0.88 0.72 0.47 154.07 100 total area 3087.31 1063.91 3114.86 2154.87 420.09 61.59 23.59 9926.22 fig. 4 transition of forest, bare surface and crops/shrubs to other land classes (1984-2015) 48 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. drainage basin would have decreased in size from 23.59 km2 in 2015 to mere 4 km2 by 2046. the predicted 2046, land use and land cover change in osun drainage basin, nigeria is presented in figure 5. fig. 5 the predicted, land use and land cover for 2046 in osun drainage basin, nigeria in summary, the change detection transition matrix between 2015 and 2046 (table 6) indicates that:  about 16% of the bare surface in 2015 will be converted into built-up area by 2046;  there will be no significant decrease in built-up areas, rather it will increase from 1063.91 km2to 1658.85 km2;  about 34% of wetland would have been converted to built-up area;  significant areal extent of about 1349 km2 of forest will be converted to crops/shrubs; and  water bodies will remain about 96.61% of its size in 2015 by 2046. conclusion in conclusion, land use/land cover change for the period 1984-2015 were examined based on the data generated from satellite imageries. lulc change transition matrix was computed with a view to determining the percentage change of one land class to another during the period of study. also, the future lulc change was simulated for the year 2046, to understand the level and direction of change that might be experienced in the future in osun drainage basin. the lulc change in the basin revealed that built-up area increased by about 235% between 1984 to 2015. forest area declined by 59% and crops/shrubs increased with about 89%, during the same period. the rate of change of lulc in the osun drainage basin may not be unconnected to population increase and settlement expansion with their accompanying anthropogenic activities which include fuel wood extraction, wood logging, and sand mining, etc. all these anthropogenic activities resulted into the loss of the original rainforest in the basin. the land use/land cover change scenario in osun drainage basin will influence the water budget and hydrology of the study area, with the probability of changing the rate of interception, evapotransipiration, runoff and groundwater recharge in the basin. in fact, the predicted future lulc change suggests that only about 12% of the basin will remain under forest cover by the year 2046. the results have underscored the increasing human occupation and the high rates of conversion of the natural vegetation into other land use classes. the rate at which forest cover declined in osun drainage basin unabated is a pointer to the fact that even after the united nations millennium development goal (mdg) terminated in 2015, one of her goals to ensure environmental sustainability by reversing the loss of forests in all regions of the world was not met in sub-saharan africa and nigeria in particular. it is paramount that the rate of deforestation and unregulated land use in the larger part of the basin be discouraged for a sustainable drainage ecosystem. in addition, the planting of the lost native trees should be encouraged for the sustainability of the basin’s ecosystem. table 5 predicted land use/land cover change between 2015 and 2046. the signs + and indicate increase and decrease, respectively land use/land cover types 2015 2046 2015-2046 average rate of change (2015-2046) area (km2) % area (km2) % area (km2) % area (km2) % 1 bare surface 3087.31 31.1 3275.32 33.00 188.01 6.09 5.88 0.19 2 built up areas 1063.91 10.72 1658.85 16.71 594.94 55.92 18.59 1.75 3 crops/shrubs 3114.86 31.38 3311.11 33.36 196.25 6.30 6.13 0.20 4 forest 2154.87 21.71 1257.18 12.67 -897.69 -41.66 -28.05 -1.30 5 rock outcrops 420.09 4.23 359.79 3.62 -60.30 -14.35 -1.88 -0.45 6 water bodies 61.59 0.62 59.93 0.60 -1.66 -2.70 -0.05 -0.08 7 wetland 23.59 0.24 4.04 0.04 -19.55 -82.87 -0.61 -2.59 total 9926.22 100 9926.22 100.00 ashaolu et al. 2019 / journal of environmental geography 12 (1–2), 41–50. 49 acknowledgement this article is part of the ph.d. work of the first author. the authors acknowledge the united state geological survey (usgs) for the landsat images used in this work, and the developers of modules for land use change evaluation (molusce) plugin in qgis. references akinwumiju, a. s. 2015. gis-based integrated approach to groundwater potential assessment of osun drainage basin, southwestern nigeria. 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(ph.d. thesis), university of ilorin, ilorin, nigeria. ashaolu, e. d. 2016. the osun drainage basin in the western lithoral hydrological zone of nigeria: a morphometric study. geografia-malaysian journal of society and space 12 (8), 71–88. ashraf, a. 2013. changing hydrology of the himalayan watershed. current perspectives in contaminant hydrology and water resources sustainability. p. m. bradley, intechopen, doi: 10.5772/54492. butt, a., shabbir, r., ahmad, s. s. aziz, n. 2015. land use change mapping and analysis using remote sensing and gis: a case study of simly watershed, islamabad, pakistan. the egyptian journal of remote sensing and space sciences 18, 251–259. doi: 10.1016/j.ejrs.2015.07.003 fasona, m. j., omojola, t. 2005. climate change, human security and communal clashes in nigeria. paper presented at international workshop on human security and climate change, holmen ford hotel, oslo, october 21st – 23rd, 2005. foody, g. m. 2002. status of land cover classification accuracy assessment. remote sensing of environment 80(1), 185–201. doi: 10.1016/s0034-4257(01)00295-4 gasu, m. b., nicholas, e., bidmus, m. a., dawam, p. d. 2016. geospatial analysis of land use dynamics in osogbo between 1986 and 2012. abuja journal of geography and development 4(1), 52–68. hammad, m., mucsi, l., van leeuwen, b. 2018. land cover change investigation in the southern syrian coastal basins during the past 30-years using landsat remote sensing data. journal of environmental geography 11 (1–2), 45–51. doi: 10.2478/jengeo-2018-0006 ifabiyi, i. p. 2005. construction versus yield of deep wells in the regolith aquifer of osun river basin, nigeria. water resources 16, 1– 16. ismail, m. h., jusoff, k. 2000. satellite data classification accuracy assessment based from reference dataset. international journal of geological and environmental engineering 2(3), 23–29. jyrkama, m. i., sykes, j. f. 2006. the impacts of climate change on groundwater. in: delleur, j. w., (ed.), the handbook of groundwater engineering, 2nd ed., crc press, usa, 1320. lerner, d. n. 2002. identifying and quantifying urban recharge: a review. hydrogeology journal 10, 143–152. doi: 10.1007/s10040-001-0177-1 lerner, d. n., issar, a. s., simmers, i. 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(ph.d. thesis), obafemi awolowo university, ile-ife. salami, a. t, ekanade, o., oyinloye, r. o. 1999. detection of forest reserve incursion in south-western nigeria from a combination of multi-data aerial photographs and high resolution satellite imagery. international journal of remote sensing 20(8), 1487– 1497. doi: 10.1080/014311699212579 tadele, h., mekuriaw, a., selassie, y. g., tsegaye, l. 2017. land use/land cover factor values and accuracy assessment using a gis and remote sensing in the case of the quashay watershed in northwestern ethiopia. journal of natural resources and development 7, 38–44. doi: 10.5027/jnrd.v7i0.05 tilahun, a., teferie, b. 2015. accuracy assessment of land use land cover classification using google earth. american journal of environmental protection 4(4), 193–198. doi: 10.11648/j.ajep.20150404.14 turner, m. g., gardner, r. h., o’neill, r.v. 2001. landscape ecology in theory and practice: pattern and process. springer-verlag, new york. weng, q. 2001. a remote sensing-gis evaluation of urban expansion and its impacts on surface temperature in the zhujiang delta, southern china. international journal of remote sensing 22(10), 1999–2014. doi: 10.1080/01431160152043676 ziegler, a. d., giambelluca, t. w. 1997. importance of rural roads as source areas for runoff in mountainous areas of northern thailand. journal of hydrology 196(1-4), 204–229. doi: 10.1016/s0022-1694(96)03288-x introduction study area materials and methods results and discussion land use/land cover classification, 1984-2015 land use/land cover change, 1984-2015 land use/land cover change, 1984-2000 land use/land cover change, 2000-2015 land use/land cover change, 1984-2015 predicted future land use/land cover change in osun drainage basin, 2046 conclusion acknowledgement references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iv. no. 1-4. pp. 1-10 the structure and origin of loess dolls – a case study from the loesspaleosoil sequence of süttő, hungary barta, g. 1 1 elte institute of geography and earth sciences, department of physical geography, budapest, hungary abstract the research of secondary carbonates from loess-paleosoil sequences focuses not just on the micro-scale types, but as well on the macroscale ones. loess dolls or concretions belong to this last category. concretions are found frequently under the paleosoil levels referring to a very probable connection with leaching processes and precipitation from carbonate-rich solutions. research was carried out on the loess-paleosoil sequence of süttő, hungary. the methods used in this work were the morphological description of concretions, the analysis of the structure after cutting into two or more parts and treatment with 10% hydrochloric acid. altogether 29 samples were analysed from the sandy loess layers between the depth of 0.65–5.55 m and 12.70–14.75 m. based on the results three main types concerning the inner structure of the concretions were determined: a.) concretions with longitudinal and/or perpendicular cracks; b.) concretions containing one or more condensation nucleus; c.) the combination of the above listed properties. from these different structures more conclusions could be drawn on the origin of loess dolls. the carbonate precipitation could have taken place in or around cavity systems of biogenic origin (as rootrelated channels or features, and biogalleries) and of non-biogenic origin (because of the structural properties of the sediment). as precipitation nuclei the cementation of hypocoatings played an important role as well. a multiphase development history of the loess dolls were in many cases characteristic. key words: loess doll, concretion, secondary carbonate, loess, paleosoil introduction the genesis and morphology of loess dolls was always an exciting subject, which still has got yet opened questions. the object of this study is on the one hand to present the place of loess dolls and their genesis in the classification of secondary carbonates. on the other hand the aim of this paper is to describe the various morphology and structure of the loess dolls of the süttő loesspaleosoil section (hungary) and to draw conclusions concerning their origin and formation environment. though the primary carbonate content of the loess derives from the calcite and dolomite crystals, as being the components of the mineral dust (pécsi 1990, 1993), the formation of secondary carbonates is connected with the resettlement of carbonates during pedogenetic processes in the soil-sedimentary environment (becze-deák et al. 1997). in this processes among others biomineralization, the flow of bicarbonate solutions and the weathering of calcium-bearing minerals take part (pécsi 1990, gerei et al. 1995, becze-deák et al. 1997). among secondary carbonates microand macroscale types can be distinguished. the micro-scale features occurring in this study are the followings: a.) calcified root cells: composed of elongated calcite crystals merging into tubes in the consequence of root calcification of mainly grass species (jaillard et al. 1991, beczedeák et al. 1997); b.) hypocoatings: carbonate impregnations around plant biogalleries, which thought to be simultaneous with the dust deposition (becze-deák et al. 1997, durand et al. 2010); c.) carbonate coatings: have different subtypes and formed postsedimentary from the percolating solutions (horváth et al. 2007, barta 2011). the macro-scale secondary carbonates are represented by concretions, among which a distinction based on size can be made. to the nodules belong those pedofeatures, which are not related to natural surfaces or voids of the matrix (stoops 2003), and do not fill preexisting cracks, respectively (sellés-martínez 1996). nodules have various subtypes based on their internal and external morphology, according to formations factors as texture of the matrix, stability of the sediment structure and alternation of precipitation and dissolution processes (wieder – yaalon 1982, sellés-martínez 1996, stoops 2003, durand et al. 2010). the above mentioned factors and processes could lead to a complex fabric divided into cracks, cavities and/or recrystallized parts (durand et al. 2010), which are characteristic not just for nodules, but for concretions as well. the morphology and structure of concretions and nodules both are suggesting a multiphase history of the carbonate profile development of the sediment (khokhlova et al. 2001). in this study the term of concretion was generally used for (and description was made of) those features which minimum length was equal or larger than 1 cm. by this means nodules were ordered (based also on their characteristics) into a size range, where their maximal length is determined in less than 1 cm. nevertheless in some cases based on the structural properties the term concretion was used for features in the size range of nodules (above 0.5 cm length). concretions appear frequently under paleosoils, suggesting a very probable connection with leaching processes (ádám et al. 1954, pécsi 1993, kemp 1998). their presence indicates climatic changes since dust accumulation is characterized with more arid conditions, whereas soil development refers to more moisture and 2 barta, g. joeg iv/1-4 relatively stable surface (kádár 1954, kemp 1995). the carbonate is leached out from the eluvial horizon of the paleosoil and accumulates in the underlying loess (jiamao et al. 1997). concretions are not just linked to leaching processes after the soil was fully developed, but during this evolution when the porosity of loess changes it leads to a loss of carbonate content as well. the percolating solutions dissolve the carbonate of the coated grains and detrital elements of loess and transport it into deeper parts of the sequence (kádár 1954, kriván 1955). the formation of loess dolls begins under the soil level as a concomitant of soil development (kádár 1954). during this redistribution of carbonates the later on infiltrating solutions can also add more precipitated carbonate to the concretions, which cause their growth (pécsi 1993, kemp 1998). concretions of the loess-paleosoil sequences can be determined as “glomerulus” concretions (seilacher 2001), referring to a ground water connected derivation. these forms are mostly spheroid and merged with each other, having protuberances on their surfaces. not just ground water could have taken part in their formation, but any percolating bicarbonate solutions. the different external appearance of concretions makes possible various associations for the description, this is why concretions in loesspaleosoil sequences are often called loess dolls. soils which are developed on loess and have different hydromorphic properties, thus they can be characterized by different loess doll types (dultz – schäftlein 1999), which could also be characteristic for the paleosoils. it is interesting, that into the loess wells or into loess tunnels (both forms caused by piping) the rainfall is able to infiltrate more effectively and reach the deeper parts of the sequence. these surfaces are mostly paleosoil levels with rather high clay content and are quite impermeable. on these surfaces the precipitation of carbonates is also possible (bulla 1933). loess dolls are not made of pure carbonate, because they contain non-calcareous particles, clay and silt in 3040 weight% (pécsi 1993). the carbonate content of the concretions fluctuates between 60-95% (pávai-vajna 1909, kriván 1955) and contains in certain proportion mgco3 as well (kriván 1955). in original (mostly vertical) position loess dolls show an uneven distribution in loess (kádár 1954). although they can appear in horizontal or in slope position, referring to reworking processes. after a presumed erosion of a loess layer a lag surface composed of loess dolls may remain in the deposit when dust accumulation continues later on (kádár 1954). in undisturbed position the shape of the loess dolls is mostly elongated and cylindrical, in accordance with the precipitation from the downward percolating solutions (kádár 1954), although the original position is not necessary vertical. the shape of the concretions can be rounded (especially the smaller ones) or irregular (having more than one axis). according also to dultz and schäftlein (1999) loess dolls found under well developed soils (e.g. chernozems) and hydromorphic soils (e.g. gleysols) usually have protuberances on their mostly smooth surfaces. while concretions developed under mineral soils (e.g. cambisols) have mostly rounded or from elongated to angular shape with rough, pitted surfaces. flat loess dolls with plate or disc-like shapes may be built up, when the level of ground water reached the formation zone of loess dolls which results in the lateral spreading of the downward flowing solutions (kádár 1954). the formation of rattle stones is used to be ordered to such zones. rattle stones are maybe built up around condensation cores with clay coatings which could dry out and shrink due to later on desiccation. then the shriveled parts give a clinking noise inside the concretion. based on dultz and schäftlein (1999), the origin of shrinkage cracks in a loess doll is not connected with higher clay content, but possibly is connected with desiccation. when the pores of the concretion are not completely filled with carbonate and are still containing some water, subsequently cracks appear because of loosing water. this may also play a role in the formation of loess doll composites, namely concretion-in-concretion structures, which can also be called as rattle stones. in this case a loess doll was grown around by carbonate from later on precipitation. the structure of loess dolls can either be compact or hollow (ádám et al. 1954), but in both cases is often divided into two parts, where an outer crust of various widths surrounds a central core (sellés-martínez 1996). when the carbonate is precipitated in a cavity system with biogenic origin, it is going to be represented in the inner structure of the loess doll (dultz – schäftlein 1999). formerly the origin of loess dolls was connected with the effect of the surface vegetation, which means that loess dolls could have been formed around roots. it was also based on the fact, that their various morphology corresponds to the shape of root ramifications or in many cases remains of roots were found inside the concretions (pávaivajna 1909). as it was soon mentioned, the percolation of bicarbonate solutions and leaching processes play a role in the formation of loess dolls, but it should not be left out that the process of capillary uplift may have an effect es well (ádám et al. 1954, kriván 1955). or the carbonaterich ground water which could have been sluggishly flowing on the surface or seasonally stagnating under it during the interglacials and interstadials (ádám et al. 1954). presumably loess dolls were formed in cavity systems of the soil matrix, namely in former root channels, at the ramification of root systems or in biogalleries (schäftlein 1996). these cavity systems are well exposed to air and joeg iv/1-4 the structure and origin of loess dolls – a case study from the loess-paleosoil sequence of süttő, hungary 3 the partial co2 pressure is lower, which leads to the precipitation of carbonate. very likely the better aired central part of the system and the individual cavities were preferred by the carbonate precipitation (in connection with the fact, that carbonate content is higher in the central section of the loess doll). it cannot be precluded, that if non-calcareous particles were in the cavity system, they may acted like condensation cores and were overgrown by calcite (schäftlein 1996). study area the study site is the loess-paleosoil section of süttő, hungary (fig. 1). the sequence is covering the süttő travertine complex exposed in the hegyháti quarry, not far from the settlement of süttő. the freshwater limestone is deposited on the right bank of the river, on the v. danube terrace in the foreland of the gerecse mountains. the age of the travertine was recently determined by uranium-series dating (sierralta el al. 2010) and the complex was dated to the middle-pleistocene. on the loess-paleosoil complex different investigations were carried out (such as optically stimulated luminescence dating, amino-acid racemization, radiocarbon dating and magnetic susceptibility, see novothny et al. 2009, 2011). the süttő loess-paleosoil site is a perfect mine of information about the paleoenvironmental changes of the late pleistocene. fig. 1 the location of süttő, hungary the sequence (fig. 2) could be divided into different units based on the properties of the sediment. during the examinations of loess dolls this division of novothny et al. (2011) was used. the succession is compartmentalized into sandy loess (units 2, 4, 7, 16), laminated greyish sandy loess (units 3, 5), loess (units 9, 11, 13) and sand (unit 8) horizons. paleosoils are represented by a light brown paleosoil (unit 6), two brownish paleosoils (units 10, 12) and a well developed pedocomplex (unit 14 as a dark chernozem-like paleosoil and unit 15 as a reddish brown paleosoil). fig. 2 the loess-paleosoil sequence of süttő, hungary (based on novothny et al. 2011) unit 1 – recent soil (chernozem); unit 2, 4, 7, 16 – sandy loess; unit 3,5 – grey, laminated sandy loess; unit 9, 11, 13 – loess; unit 6 – light brown paleosoil; unit 8 – sand; unit 10, 12 – brown paleosoil; unit 14 – dark chernozem-like paleosoil; unit 15 – reddish brown paleosoil; unit 17 – sand; unit 18 – travertine 4 barta, g. joeg iv/1-4 methods the loess-paleosoil sequence was analysed in 10 cm vertical resolution and loess dolls were collected based on this division on the field. smaller concretions were separated after wet sieving of the bulk loess/paleosoil samples, according to the 10 cm vertical resolution from 100-150 g material on a 500 μm sieve. different kinds of investigations were carried out on samples from unit 2 and unit 16. concerning to whole profiles loess dolls were described first on the grounds of their morphology connected with the horizon in which they were found. altogether 23 samples were cut into two or more parts according to the size of the loess doll: 3 samples from unit 2 and 20 samples from unit 16. experiments were carried out on certain samples by using 10% hydrochloric acid to dissolve their carbonate content. the treatment with 10% hydrochloric acid was gradual, loess dolls were dipped into the acid then taken out and put into distilled water. this process was repeated successively until the samples were totally dissolved. the aim was to check the phases of the dissolution and describe the inner structure of the loess dolls (and also to determine the insoluble residues). altogether 6 samples were treated this way: 4 samples from unit 2 and 2 samples from unit 16. loess doll samples were only taken from unit 2 and 16. from unit 3 to unit 9 in the meanings of the classical description no loess dolls were found. in the units 69 some features appeared in the maximal length of 2 cm, but their morphology could be linked more to the hypocoatings, although these samples had a more massive and cemented substance than hypocoatings. these features may act like the first stage of becoming a loess doll or maybe they are just being stuck in this phase because there was no significant leaching (and by this means not enough amount of percolating solutions). from the units 10-15 no samples were taken either. under the two brown paleosoils (units 10 and 12) no table 1 frequency distribution of loess dolls sequence depth (cm) frequency distribution of loess dolls* sequence depth (cm) frequency distribution of loess dolls* unit 2 0.65-0.75 ++ unit 2 4.15-4.25 ++ 0.75-0.85 ++ 4.25-4.35 ++ 0.85-0.95 4.35-4.45 ++ 0.95-1.05 + 4.45-4.55 +++ 1.05-1.15 4.55-4.65 ++ 1.15-1.25 ++ 4.65-4.75 + 1.25-1.35 4.75-4.85 1.35-1.45 4.85-4.95 1.45-1.55 +++ 4.95-5.05 1.55-1.65 ++ 5.05-5.15 1.65-1.75 +++ 5.15-5.25 1.75-1.85 + 5.25-5.35 1.85-1.95 + 5.35-5.45 1.95-2.05 + 5.45-5.55 2.05-2.15 unit 6 12.70-12.75 + 2.15-2.25 ++ 12.75-12.85 +++ 2.25-2.35 +++ 12.85-12.95 ++ 2.35-2.45 + 12.95-13.05 + 2.45-2.55 + 13.05-13.15 + 2.55-2.65 13.15-13.25 ++ 2.65-2.75 13.25-13.35 ++ 2.75-2.85 13.35-13.45 ++ 2.85-2.95 13.45-13.55 + 2.95-3.05 13.55-13.65 + 3.05-3.15 13.65-13.75 + 3.15-3.25 13.75-13.85 3.25-3.35 13.85-13.95 + 3.35-3.45 13.95-14.05 + 3.45-3.55 14.05-14.15 +++ 3.55-3.65 14.15-14.25 + 3.65-3.75 14.25-14.35 ++ 3.75-3.85 14.35-14.45 ++ 3.85-3.95 14.45-14.55 + 3.95-4.05 14.55-14.65 ++ 4.05-4.15 14.65-14.75 + *frequency distribution based on the number of samples (l=loess doll): +: 1≤l<3; ++: 3≤ l<6; +++: 6≤l≤9 joeg iv/1-4 the structure and origin of loess dolls – a case study from the loess-paleosoil sequence of süttő, hungary 5 loess dolls were found, because these levels have not gone through a strong leaching (unit 10 has a carbonate content varying between 14-15%; while unit 12 has 914%; barta 2010). however a probable gap during sedimentation also cannot be left out of account. the dark chernozem-like paleosoil (unit 14) and the reddish brown paleosoil (unit 15) are very strongly leached and their carbonate content is re-precipitated under the pedocomplex. secondary carbonates are only available on the both sides of the upper and lower decalcification boundary in the forms of hypocoatings and calcified root cells. results – unit 2 loess dolls are found in unit 2 between two depth ranges: a.) under the recent soil level (below 0.70 m) to 2.55 m, almost in every 10 cm intervals with the frequency distribution of one to nine samples; b.) between the depth range of 4.25 and 4.75 m with the same frequency distribution (table 1). below the recent soil to the depth of 2.55 m carbonate concretions are quite frequent and to the depth of 1.15 m they generally have rough, porous surfaces divided with channels. their mean length is 1 cm and mean width is 0.5 cm. at 1 m depth loess dolls are characterized with elongated, curving shapes with the length of 0.5-3 cm and width of 0.3-1.3 cm. their surface is divided with small channels, in which calcified root cells or calcitic membranes can be found in some cases. such small concretions occur also which take a shape of a former land snail shell. it means that the bicarbonate solutions could have been percolating through the shell and then precipitated the carbonate within, but later on the shell could have been broken off. some concretions were quite easy to break into parts with hands, which revealed two different inner colours: a.) greyish colour of the compact, crystallized inner part; b.) yellowish to light brownish colour of the more porous than compact inner part (having the same colour as the outer crust of the concretion). from the depth between 1.15 m to 1.25 m concretions appeared to have the same morphology as above described with mean length of 1.8 cm, but mostly became thinner on their central part. the concretions from the depth between 1.45 m to 2.55 m have length between 0.5-2 cm and can be characterized with an outer crust and an inner core in the colour of grey, which is compact. such kind of concretion appeared as well, which had a small channel leading through it. then concretions appear again from the depth of 4.15 m to 4.75 m. these samples have a longitudinal axis but irregular shapes in the length between 3-5 cm and width between 0.5-1.5 cm. in unit 2 below this depth no more concretions were found. loess dolls cut into two or more parts samples were taken from the depth of 0.85 m, 1.05 m and 1.55 m (fig. 3). these concretions have a longitudinal axis ranging between 1.2 1.8 cm and their width is varying between 0.5-0.9 cm. their form is mostly elongated with rough surfaces, while their inner parts are less compact and crystallized. the inner structure of the concretions can be characterized by cracks either parallel with the longitudinal axis or perpendicular to it. in the sample from 0.85 m two main cracks appear parallel with the longitudinal axis, while the sample from 1.55 m has only got one crack parallel with the longitudinal axis. the concretion from 1.05 m has one crack parallel with the longitudinal axis, which is connected to a crack at an angle of 45° (like forming of a letter of “v”). loess dolls treated with 10% hydrochloric acid the sample from the depth of 0.85 m has rough, pitted surface divided with channels. it seemed to be built up from different parts through cementation. during the gradual treatment with 10% hydrochloric acid many small fig. 3 inner structures of loess dolls after cutting into parts samples taken from: a – 0.85 m; b – 1.05 m; c – 13.55 m. the concretions a and b are divided into cracks, while the sample c has a porous inner structure with a double core (double condensation nuclei) 6 barta, g. joeg iv/1-4 channels emerged also with calcified root cell structures. the longitudinal axis of the concretion was marked with two transversal smaller cracks. the inner structure was not porous, but compact and well crystallized. the sample from the depth of 0.95 m has a length of 1.5 cm and width between 0.4-1.1 cm. during the gradual treatment with 10% hydrochloric acid the small channels with the outer crust have been dissolved and showed the inner core with a crack system. inside the crack system a calcified root cell structure was found. the inner structure of the sample from the depth of 1.55 m is characterized by a crack system. during the gradual treatment with 10% hydrochloric acid the structure of the sample was continuously checked under a binocular microscope. on the surface of the crystalline inner matrix a brownish fading was recognized and the rest material after the total dissolution of the concretion were gelatinous membranes in the extension of 2x6 mm. it was the only sample in which these features were present. the concretion from the depth of 2.45 m has an outer crust and compact, well crystallized inner core in the colour of grey. this inner core is characterized with a small channel. walls of the channel have the same yellowish colour like the outer crust. during the gradual treatment with 10% hydrochloric acid two parallel channels appeared along the longitudinal axis of the concretion. it was also observable that the inner parts dissolved faster than the outer crust. results – unit 16 loess dolls are present in high amount in unit 16, they are detectable from the whole sequence from every 10 cm interval with the exception of 13.75 m – 13.85 m (table 1). along unit 16 the size of the loess dolls is alternating in length between 0.4-4 cm and in width between 0.2-2 cm. in general their surface is rough, divided with small channels (which are often filled with calcitic membranes). in the upper third of unit 16 calcified root cells and manganese infilling can occur also in these small channels of the surface. concretions with smooth surfaces occurred in the lower third of unit 16 together with the ones with rough surfaces. after cutting into parts the loess dolls showed different structures. no characteristic crack system leads through the concretion these kind of loess dolls are characteristic for the whole unit 16. samples were taken from the depth of 12.75 m, 13.15 m, 13.35 m, 13.45 m and 13.95 m. in general these concretions are 1-2 cm in length and 0.5-1 cm in width and have a more porous outer crust than their inner core. appearance of cracks the loess doll from the depth of 12.75 m in the shape resembling a hut, has a length of 6 cm and width between 1.2-4 cm. its outer crust is more porous, while the inner core is compact. in the middle zone of the concretion there is a main crack perpendicular to the longitudinal axis, and into which four smaller cracks are joining with a certain degree. the main crack does not lead through the whole length of the concretion. besides the cracks smaller pores and nuclei are visible, but they are mostly present in the ending of the concretion. porous inner part the loess doll from the depth of 13.55 m has a length of 5.5 cm and width between 1.0 and 2.5 cm (c on fig. 3). it is characterized with a double core in which lot of small sized channel are found, which makes it so porous like a sponge. loess dolls from the depth of 14.15 m show the same sponge-like structure but have only one core. another loess doll from this depth resembled the same structure, but with two separated larger pores besides the many small ones. the loess doll from the depth of 14.55 m is also divided into many small pores which are present in a higher amount towards the outer crust of the concretion. inner core consisting of more parts two loess doll samples are examined from the depth of 13.15-13.25 m. the one with a length of 5.3 cm and width between 1-2 cm has a compact inner core surrounded ring-like by another compact layer, which is followed by the outer, thinner and more porous crust. a slice of the sample shows a small nucleus in the inner core. the other loess doll has a length of 2.5 cm and width of 1.8 cm and resembles the same structure, just without having a nucleus. relatively homogeneous inner structure the loess doll from the depth of 13.35 m has a length of 1.9 cm and width of 1 cm, while the samples from the depth of 14.45 m has a length of 3 cm and width between 0.7-1.5 cm. both concretions have no cracks or nuclei in their inner structure and are relatively homogeneous. septarian structure the loess doll taken from the depth between 12.70 m and 12.75 m, right beneath the reddish brown paleosoil, has a length of 5 cm (longitudinal axis) and maximal width of 5.5 cm which is narrowing for 1-3 cm. after joeg iv/1-4 the structure and origin of loess dolls – a case study from the loess-paleosoil sequence of süttő, hungary 7 cutting into parts and smoothing the concretion three main nuclei appeared, one of them showing a septarian pattern (fig. 4). fig.4. loess doll with septarian structure from the depth between 12.70 m – 12.75 m the three cores are marked with the letters a (septarian cracks); b (mass of small channels) and c (cementated hypocoatings) loess dolls treated with 10% hydrochloric acid the sample taken from the depth between 12.70-12.75 m, also right beneath the reddish brown paleosoil, has a length of 7.8 cm and a maximal width of 4.6 cm, which grow narrow to 0.8-2.7 cm. the shape of the loess doll resembles a croissant. during the gradual treatment with 10% hydrochloric acid different structure elements were presented in the loess doll. the concretion was divided into two main layers: a.) the outer crust built up from sandy loess, which was easier dissolving, in the same colour as the surrounding matrix; b.) the very compact, strongly cemented inner core in the colour of grey and brown. the outer crust, which was dissolving normally, showed gradually many hypocoatings joining to each other. the inner core was dissolving very slowly (maybe it refers to a higher dolomite content, than calcite), showed parallel cracks along the longitudinal axis. the sample from the depth between 13.05 m and 13.15 m has a length of 4 cm and width between 0.3-1 cm, and its surface is divided into small pores and channels. after the gradual treatment with 10% hydrochloric acid the inner structure of the loess doll seemed not be compact and one main crack appeared along the longitudinal axis with some small perpendicular cracks. discussion unit 2 two kind of inner structures are characteristic for the concretions of unit 2: a.) appearance of cracks; b.) presence of a main crack (or cracks) parallel with the longitudinal axis of the loess doll (a and b on fig. 3). the concretions are generally smaller in size than the ones of unit 16. the size extension of these loess dolls ranges between 0.5-3 cm. the size properties may be connected with a less significant degree of leaching from the recent soil level and a probably young formation age. other conditions of the matrix of the sediment can exert influence on the formation environment, like the changes of the partial co2 pressure or the capacity of carbonate uptake for the percolating solutions. the formation of the concretions could be connected with carbonate precipitation in a well aired cavity system of different size and origin (schäftlein 1996). every examined sample from unit 2 showed a certain kind of crack system. the loess doll from the depth of 0.95 m was containing in its inner part a calcified root cell structure, which refers to a combined formation environment. it means that the formation was both connected with precipitation in a cavity and around a condensation core. the cavity could have been of biogenic origin, which means it was formed by roots of presumably grass species. first the calcificaton of the roots took part, which thought to be contemporaneous with the dust accumulation (after becze-deák et al. 1997). later the cavity, which was left behind by the living root, was filled up with the calcified root cell structure, which acted as a nucleus for carbonate precipitation. these assumptions raise the possibility that this concretion is of younger age than the calcified root cell structure and was formed later on (and was still in an early development phase). at the case of the sample from the depth of 0.85 m the calcified root cell structure was found not in the central part of the concretion, but as the part of its outer crust. it may also refer to an early development phase, during which the surface of the concretion adheres continuously more carbonate and cements to itself more components of the surrounding matrix. the insoluble residues of the concretion from the depth of 1.55 m were gelatinous membranes. from this feature and the inner crack system of the concretion it may be concluded, that the carbonate content of the percolating solutions was accumulated in a cavity system of branching roots. during its formation it could have included the living root as well, which started to decay, but since than there was not enough time for the plant rests for the total decomposition. it may also refer to a 8 barta, g. joeg iv/1-4 quite young age of the loess doll compared to the level in which it was found. to sum up, it can be stated that the examined concretions of unit 2 were presumably developed in cavity systems connected with roots (based also on the works of pávai-vajna 1909, and schäftlein 1996). besides the formation in root related cavities the cracks in the concretions may have a connection with hypocoatings, namely carbonate could have been precipitated around hypocoatings (barta 2011). it can be supported by the presence of small channels dividing the surface of some concretions, and which are seem to be referring to hypocoatings during the gradual treatment with 10% hydrochloric acid. the origin of hypocoatings, which are caco3 impregnations around the pores of the soil matrix (becze-deák et al. 1997, durand et al. 2010), can either be connected with root-suction related carbonate precipitation (wieder – yaalon 1982) or evaporation of calcium-rich solutions, or with carbonate precipitation from percolating solutions respectively (becze-deák et al. 1997). although yet none of these hypothesis is proved or denied. unit 16 loess dolls appear soon right under the paleosoil complex composed of the dark chernozem-like paleosoil (unit 14) and the reddish brown paleosoil (unit 15) and in addition generally in larger size compared with the concretions of unit 2. this diversity of size can be connected with the different degree of leaching of the soil horizons. the pedocomplex is very strongly leached, which means that its carbonate content is mostly 0%, except the depth between 12.55 m and 12.65 m, where it reaches 2.08%. the effect of the strong leaching could have caused higher carbonate precipitation and accumulation rates under the paleosoil horizon. the effect of the downward percolating solutions could have been strengthened by a possible lateral groundwater flow and by valley floor position, respectively. the bicarbonate solutions were leaching through the pedocomplex and their carbonate content was precipitated in the underlying sandy loess deposits of unit 16. in the loess the percolating solutions found different conditions of porosity and changes in the partial pressure of co2. the results of the precipitation were on the one hand the formation of carbonate coatings and on the other hand the concretions (barta 2010). based on the examined loess dolls, three main observations can be established in connection with their origin: a.) carbonate precipitation around nuclei (c on fig. 3); b.) carbonate precipitation in cavity systems; c.) multiphase origin (fig. 4). in the case of the concretions having relatively homogeneous inner structure or no characteristic crack system within, may be stated that they have been precipitated around certain nuclei (like small pores and channels) and are still in an earlier phase of development. the appearance of cracks in the loess dolls can refer either to precipitation around more nuclei or small cavities. around these individually developed features later on more carbonate was precipitated and caused merging into a new concretion. for this new complex form it was easier to adhere carbonate and carry on the growth. among the loess dolls characterized by mostly porous inner parts, appears a concretion having a double core at the depth of 13.55 m (c on fig. 3). presumably it was developed around two nuclei which were growing through more carbonate precipitation and merged together, just as described above. this double core was containing lots of small sized channels and seemed to be as porous as a sponge. the possibility may be raised that these nuclei were connected with bunches of hair-thin roots which decayed later. for the formation of loess dolls having mostly porous inner parts the idea came up, that the high amount of small channels (which are responsible for the porous structure) may possibly belong to hypocoatings, which were gradually cemented together. the cementation of hypocoatings may also be conceivable for the case of the concretion from the depth between 13.05 m and 13.15 m. in its inner structure perpendicular cracks were crossing through the main longitudinal crack and the appearance of the whole system resembled a possible cementation of hypocoatings. although the above presented loess doll types were soon examples for a multiphase development, the case of the following concretions also serve this reinforcement. the loess doll with the inner core consisting of more parts is characterized by a ring-like structure. presumably the two ring-like more compact inner cores can be connected with different carbonate precipitation events (and so does the outer crust as well). it might be in connection with the assumed alternation of moist and arid phases in unit 16 (barta 2010). the loess doll beneath the paleosoil complex, which is resembling a croissant, presumably also originated through more phases: like the inner core could be connected with the primary leaching of the pedocomplex, while the outer crust was built up from the later on percolating solutions (also through more than one phase). loess doll with septarian structure was found also right beneath the pedocomplex. the term septarian means a radial crack pattern, where the cracks are narrowing towards the external boundaries of the concretion (bullock et al. 1985). this kind of structure was also described from concretions in shales (seilacher 2001). in this loess doll three different cores are present resembling the junction of channels or cracks. but these chanjoeg iv/1-4 the structure and origin of loess dolls – a case study from the loess-paleosoil sequence of süttő, hungary 9 nels may belong to cementated hypocoatings based on the appearance of the core marked with “c” (fig. 4). to confirm the role of hypocoatings in the multiphase development of loess dolls, a pedofeature was found from the depth between 14.45 m and 14.55 m. it is soon cementated and hard, but the tube shapes of the hypocoatings are still very well to be seen (fig. 5). this structure act like if being in the early phase in becoming a concretion. fig. 5 cementated hypocoatings – presumably an early phase in the formation of concretions conclusion the loess dolls of the loess-paleosoil sequence of süttő could be divided into three main types based on their inner structure: a.) concretions with longitudinal and/or perpendicular cracks; b.) concretions containing one or more condensation nucleus; c.) the combination of the above listed properties. these structures are summarized in table 2 (marked with letters from a to g), according to the depth of the sequence. from the various inner structures of loess dolls more conclusions can be drawn concerning their origin. carbonate precipitation took place in or around cavity systems either of biogenic origin (as root-related channels or features, and biogalleries) or of non-biogenic origin (because of the structural properties of the sediment). the cementation of hypocoatings can also act like precipitation nuclei and be the first phase in the concretion development. for the origin of the concretions of unit 2 mostly the root-related cavity system theory was characteristic, while the loess dolls of unit 16 were related to a multiphase development history concerning the role of cavity systems, precipitation nuclei and cementation of hypocoatings. the knowledge of the morphology and structure of loess dolls provide information on their formation environment and may be a good complementary method in the research of secondary carbonates. acknowledgements i would like to thank to dr. erzsébet horváth (elte institute of geography and earth sciences, budapest) for all of her support. i also owe thanks to dr. bernadett bajnóczi (institute for geochemical research, hungarian academy of sciences, budapest), dr. paul königer (bgr federal institute for geosciences and natural resources, hannover) and the colleagues at the leibniz institute for applied geophysics (hannover) for the opportunity of performing the preparation of loess dolls. i would also like to express my thanks to ágnes novothny for her help on the field, to katalin fehér and klaudia kiss (elte, institute of geography and earth sciences, budapest) for their help in the laboratory. the study was supported by the bilateral daad project (pmöb/844) and the hungarian research fund (otka k68219). table 2 the structural characteristics of the examined loess dolls sequence depth (m) number of samples examined characteristics of the structure unit 2 0.75-0.85 2 c: main crack parallel with the longitudinal axis 0.95-1.05 2 b: appearace of cracks; c: main crack parallel with the longitudinal axis 1.45-1.55 2 b: appearace of cracks; c: main crack parallel with the longitudinal axis 2.35-2.45 1 c: main crack parallel with the longitudinal axis unit 6 12.70-12.75 4 a: no characteristic crack system; b: appearance of cracks; c: main crack parallel with the longitudinal axis; g: septarian structure 13.05-13.15 4 a: no characteristic crack system 13.15-13.25 2 e: inner core consisting of more parts 13.25-13.35 3 a: no characteristic crack system; f: relatively homogeneous inner part 13.35-13.45 2 a: no characteristic crack system 13.45-13.55 2 d: porous inner part 13.85-13.95 1 a: no characteristic crack system 14.35-14.45 3 d: porous inner part; f: relatively homogeneous inner part 14.45-14.55 1 d: porous inner part 10 barta, g. joeg iv/1-4 references ádám l. – marosi s. – szilárd j. 1954. 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b) how have the ecological conditions of the lake evolved in the past period (zonation, succession, plantation and colonization)? c) which general experiences could be gained from the operation of this artificial thermal lake this far? the authors of the present study were already engaged in the planning process, participating in the preparation of four different design documentations. the planting design and the maintenance instructions were based on a physico-chemical monitoring, phytoplankton, zooplankton and macroinvertebrate sampling, and machrophyte assessment. the significant processes during the three years of the lake are presented by functional groups of biota, separately assessing the characteristics of the changes of macrophytes. in 2017 an individual macroinvertebrate assessment was done, moreover a fish die-off occurred in august 2017, which are mentioned separately as well. the data in total suggested that the water of the lake is highly hypertrophic, further machrophyte introduction can prevent the plant nutriments to be absorbed by algae. partly the algal growth but also the unlucky coincidence of other factors (e.g. high water temperature, cold weather front, maintenance problems) led to the dieoff of the spontaneously overpopulated fish stock in 2017. keywords: lake management, lake maintenance, thermal lake, algal bloom, macrophyte, succession, fish die-off, zalakaros introduction there are several reasons to create artificial lakes, including flood protection, providing water for irrigation and drinking, fish farming, and by opencast mining a plenty of new lakes appear in the landscape as well. aquifers and quarry ponds – irrespectively of their primary function –become areas of touristic-recreational development in many cases, moreover they are popular leisure time destinations for locals since their formation (dávid and német, 2005; furgala-selezniow et al., 2012). due to the rapid succession of water-related habitats and the intense, diverse demand of utilization, the ecological conditions and the environment of the new lakes change at a quick pace (hall and härkönen, 2006). in the interest of landscape sustainability (musacchio, 2013; wu, 2011) and the protection and improvement of the ecosystem services of the lake and the lake-shore (vinkó et al. 2012), changes must be carefully arranged (boromisza et al., 2015; illyés et al., 2016). in the course of this, it is equally required to mitigate the probable environmental impacts, to ecologically fit the new landscape feature (lake) into the landscape, to serve the needs of the society (moss, 2007), to discover the natural values and to schedule the maintenance tasks (mészáros, 2016). the tools and measures of fitting a new lake into the landscape are similar to lake restoration methods (annadotter et al., 1999; bain et al., 2000; cooke et al., 2005; estrada et al., 2011; gulati et al., 2008, ostendorp et al., 1995; sondergaard et al., 2008) in zalakaros (hungary) a complex touristicrecreational investment was planned, which aimed to create new facilities for leisure activities beyond the existing thermal bath. a visitor centre, a promenade, a colonnade, a fountain, an artificial lake with an island and bridges, a tale park, a labyrinth, a water obstacle course, a parking, meditation space of the lights, seniors’ active recreation park, and a nature trail were among the planned elements. the peculiarity of the lake is its water quality, as it is filled with the drain-off water of the thermal bath. after creating a new lake, it requires several years for the water ecosystem to evolve (straskraba, 1994), and might be surprising, especially in case of a thermal lake. fitting a new landscape element into the landscape is a functional, ecological and aesthetical challenge, which can be actually realised through several designs and numerous interventions. the authors of the present study were already engaged in the planning process, participating in the preparation of four different design documentations. the aim of this study is to conclude the 18 boromisza et al. (2018) experinces of the maintanence practice of the last three years of an artificial lake. therefore, in our study the first three years (2015-2017) of the development of the lake were analysed and evaluated, along the following questions: a) what kind of design processes and maintenance interventions are related to the process of fitting the lake into the landscape? b) how have the ecological conditions of the lake evolved in the past period (zonation, succession, plantation and colonization)? c) which general experiences could be gained from the operation of this artificial thermal lake this far? study area the study area and the thermal lake is located in western hungary, at the administrative area of zalakaros town. there are closed forests on the eastern side of the lake, and gallery forests on the south (fig. 1). the surface area of the artificial lake is 12900 m2, its average water depth is 1.5 m (with a shallow cover of 0.4 m at a part of the lake bed around the “flagstones”), its maximum depth is 1.8 m, its volume is 19000 m3. the length of the shoreline is 484 m, the shoreline development index is 1.2 without the island, and 1.41 including the island. the lake is isolated; its water supply is ensured by using the drain-off of the thermal water ((in other words: used bathing water). the daily amount of the bath’s excess water is 600-800 m3. the average detention time in the lake is approximately 30 days. the banks’ average bend is 1:2, and are covered by crushed limestone which unfavourably limits the vegetation growth. the lake is functioning as a “park lake”, providing aesthetical value to the city. it is prohibited to use this lake for bathing and swimming it serves only spectacular purposes and not further balneological ones. methods the planting design and the maintenance instructions were based on a physico-chemical monitoring (concluded between 2015 and 2017, on average once a month, based on own samplings and data retrievals of the lake’s operator: surface water sampling considering the hungarian standards msz 12750-2:1971, msz iso 5667-1:2007, msz iso 5667-4:1995, msz iso 56676:1995). there was a regular sampling in order to analyse phytoplankton (between 2015 and 2017, four times a year, between april and august): the water samples were condensed on a filter, and their qualitative examinations were made under microscope in order to determine the dominant species in the phytoplankton. there were difficulties to filter the sample on the usual 0.45 micrometre pore size filter plate, thus the second occasion 3 micrometres pore size filter plate was applied. parts of the condensed samples were examined in different enlargements. at the same time of phytoplankton sampling zooplankton was also sampled by using plankton net with 150 micrometre of pore size. almost 70 l water was filtered through plankton net on site, and the material remained in the sample container of the net was examined under microscope. the dominant species were determined in the sample. the analysis of macrophytes (qualitative characterization, recording the alteration tendencies of certain species) were done twice a year between 2015 and 2017, between april and september. the sampling of the macroinvertebrates took place in september 2017 with net techniques, at four points of the lake, identifying the individuals in place and valuing their prevalence. the main danger in this lake is the planktonic eutrophication because the algae can prohibit the growth of the macophytes planted in the lake. that is why chlorophyl-a concentration was a dominant water quality parameter that was also measured several times in a year in an accredited laboratory. according to the oecd scales (oecd, 1982) if the chlorophyl-a yearly maximum concentration is between 2.5-8 mg/m3 than the lake is oligotrophic. 8-25 mg/m3 is the mesotrophic range, 25-75 mg/m3 is the eutrophic one and >75 mg/m3 is the hypertrophic limit. the hypertrophic status can be dangerous for macrophytes and aerobe heterotrophic organisms living in the lake. the high primary production of the phytoplankton can cause very high oxygen level in daytime but oxygen depletion and fish kills in early morning. fig. 1 location of the study area every start is challenging: fitting a new artificial lake into the landscape, zalakaros, hungary 19 results evaluating the fitting into the landscape and the lake maintenance the maintenance decisions regarding the lake are primarily based on the maintenance plan of the lake and it is implemented through numerous – partly continuously or cyclically occurring – interventions (table 1). the first challenge appeared before the construction of the new thermal lake’s bed: the forest where the lake was going to be constructed was a habitat of protected species: spring snowflake (leucojum vernum) and white hellebore (veratrum album). to solve the problem the habitat map of the protected plant species in 2013 was prepared and a botanical analysis of the transplantation site and the area of the new lake was carried out. the adequacy of the transplantation site was analysed and a recommendation about the transplantation of the protected species was presented. unfortunately, there has been no monitoring activities going on about the success of the transplantation since it happened, however, based on the experiences of regular field surveys it is obvious that high number of individual plants of both species can be found in the transplantation area. the interpretation and introduction of natural values to visitors were defined as a goal in the transplantation area of the protected species: the next step of the design process was to design a nature trail constructed of plank in 2015. the design and the realization of the nature trail required not only technical work, but also to prepare complex, high quality, unique graphical materials based on ecological and pedagogic knowledge. thus it became a holistic process, the foundation of creating facilities which provide adventurous and attitude-changing experiences. once it was possible to form and fill the new bed, the next design challenge was to accomplish the plantation of the lake – thus contributing to the landscape fitting ecologically as well. besides their aesthetical and habitat significance (providing hiding-place, foraging space, nesting site and spawning ground to several animal species), aquatic and riparian plants have a striking role in the design area from the aspect of water quality: by their nutrient uptake and shading, they can limit the unfavourable excess growth of algae, moreover the oxygen production of some submersed species is notable in the water as well (brown et al. 1974; maberly and spence, 1989; scheffer, 2004; szilágyi, 2001). to prevent the dominance of algae, at least 30-40% of the water surface has to be covered by macrophytes (higher order aquatic and riparian plants) (brown et al. 1974), which might take several years. consequently, the primary role of the recommended planting design was to contribute to the conservation of the water quality, to create ornamental plant cover on the water surface and to form aesthetical focal points on the lake. the method of planting was significantly influenced by the realized construction works and its structure: the formation and isolation of the bed, its bottom and the formation of the banks. the fact that no planting medium and reed berm were created is a determining factor (thus in the case of the banks, a different planting method had to be applied.) in the course of choosing the species and creating the spatial arrangements the lake’s natural aptitudes defined the basic criteria: the peculiarity of water quality, exposure to undulation, the morphological aptitudes of the lake – its depth conditions, temperature conditions and solar access. considering the above aspects, 6 riparian (1446 specimens), 4 floating leaf (248 specimens) and 2 submersed aquatic species (20 specimens) were included on the species list. while carrying out the different planting methods, adequate timing and setting water level needed for construction works were of high importance. the water had to be let down before planting the aquatic plants. the floating leaf nymphaea species were placed at 1 pcs/3m2 density, in water planting baskets lined with linen sacks. considering the depth of the lake, the baskets of younger nymphaea plants were not directly placed on the bottom but raised by brick columns. table 1 overview of the design process and management interventions related to the lake design time construction, intervention, arrangements time transplantation plan of the protected plants september 2013 transplantation october 2013 planting design of the lake march 2015 plantation of riparian and aquatic plants july-august 2015 nature trail design november 2015 nature trail december 2015 maintenance plan of the lake april 2016 phyisico-chemical monitoring 2015-2017 phytoplankton and zooplankton analysis 2015-2017 macrophyte assessment 2015-2017 macrophyte replacement october 2016 macroinvertebrate assessment september 2017 vinegar weed control on banks april-september 2017 filamentous green algae removal april-september 2017 macrophyte cut-back october-november 2015-2017 application of bleaching powder august 2017 20 boromisza et al. (2018) the submersed species also had to be planted directly to the bottom, in a density of 3 pcs/m2. planting on the banks protected by rip-rap demanded an untraditional procedure as well. proper quality rhizomes had to be collected of riparian plants (mostly: typha angustifolia) (hawke and josé, 2002; henderson et al. 1999; robinson, 2006) that were surfaced from canal dredging in the region. the rhizomes wrapped in jute sacks had to be fixed between the bank’s rocks, 30-50 cm under the operating water level. the riparian plants in the shallow area were distributed at operating water level, at an average stem distance of 50 cm, placing the planting baskets directly on the bottom (fig. 2). the maintenance plan of the lake was completed in april 2015, then for the request of the local government it was modified in april 2016 and revised in november 2017. the different monitoring activities and condition analyses were constant maintenance tasks. certain factors were only analysed occasionally (e.g. the macroinvertebrate assessment was carried out only once in september 2017). part of the maintenance tasks were previously known, planned and scheduled (e.g. the winter cut-back of macrophytes), while others required individual decisions and quick reactions based on the actual water quality (e.g. application of bleaching powder). phyisico-chemical water quality the first analysis results related to the lake were the abiotic factors. concluding the data acquired between 2015 and 2017 it was found that the chemical water quality of the lake was characterized by high salinity, relatively high ph, low concentration of plant nutrients, that can be uptaken by algae and low organic matter content. the chemical characteristics of the lake were determined by the water quality of the supply wells, moreover – due to the long detention time – they softened the alterations definitely present in the operation of the bath, thus the changes of the water quality were not significant and slow. the lake was fed by the used thermal water of wells filtered at 1200 m and 2000 m deep, and rainwater. analysing the data of 2017 more in details, the following were ascertained (the results of our own samplings are shown in the table 2). the typical transparency/secchi depth of the water was 50 -75 cm. regarding the medium depth this means that the light was not able to reach the surface of the sediment constantly on all sites, impeding benthic photosynthesis. considering that the water of the lake did not constantly contain excess algae, the inorganic colloidal materials, which got to the water through the sediment or could be developed throughout chemical precipitation in the lake, were highly responsible for the low transparency. in total their shade was beneficial as during periods with excess algae benthic photosynthesis was not favourable. amongst the plant nutrients, the concentration of the absorbable nitrogen forms was constantly low according to the samplings: the concentration of nitrite and nitrate was usually under the measuring range, and the concentration of ammonium was low as well, not contributing to algae growth. the concentration of phosphorous forms was similarly low, under the measuring range. in the water of the bath the concentration of these nutrients was very low, those that were still present were immediately absorbed by the algae in the lake. as per our opinion, the main nutrient sources were primarily the sand layer covering the lake, secondary the atmospheric drift (dust). fig. 2 formation of the lake bed and the planned macrophyte plantings at the shallow area of the lake (near the “flagstones”) every start is challenging: fitting a new artificial lake into the landscape, zalakaros, hungary 21 the chemical oxygen demand of the water was usually low – as it is typical in the case of a water beforehand used for bathing. the high cod values were related to the high algae concentration. in case of the highest a-chlorophyll concentration cod values were close to the values of purified sewage, although it was caused by the high algae organic matter content, which is particularly unfavourable. salt content is also mentionable (conductivity), including the chloride concentration. it was noticeable that the approximately 2200 µs/cm conductivity measured in winter and spring increased above 3000 µs/cm by the summer, beside a chloride concentration of approximately 1000 mg/l. at the end of august conductivity was stably above 3800 µs/cm, and chloride concentration increased above 1440 mg/l as well. this alteration could be caused by three reasons: (1) the bath availed itself more of the deeper well with higher salinity; (2) the unusually hot summer (with 56 record hot days that year) resulted in the concentration of the lake’s water; (3) the input pump was broken for a long time, and the lake received fresh water only through a low performance supplementary pump, which contributed to the concentration of soluble ions including chloride. at both sampling points the conductivity of the water was high, and similar to each other. at the area around the flagstones the water supply came from the same source as the water supply of the lake, thus there was no possibility for a significant difference. the temperature of the water was 1.1oc colder than at the bridge. around the steps oxygen supersaturation was observed in the water which is the result of the significant photosynthetic activity. this could be the result of the oxygen production of the phytoplankton and cladophora sp. though this supersaturation was significant, it would not have required intervention itself. exceptionally significant oxygen supersaturation was observed in the water around the bridge which was the result of the very high photosynthetic activity of the phytoplankton. the oxygen production was so strong that the produced gas bubbled out of the water. due to the strong photosynthetic activity the ph became highly alkaline. the data in total suggested that the water of the lake is highly hypertrophic, which was indicated by the greenish-brownish colour of the water as well. it is necessary to avoid the hypertrophic conditions in the lake because the valuable planted macrophyte vegetation can loose the competition for light and plant nutrients against phytoplankton. changes of biota the main goal of fitting the lake into the landscape and the maintenance of the lake was to reach a favourable ecological condition, which was the base of the aesthetical value and the utilization of the lake as well. the significant processes during the three years of the lake were presented by functional groups, separately assessing the characteristics of the changes of macrophytes (table 3). in 2017 an individual macroinvertebrate assessment was done, moreover a fish die-off occurred in august 2017, which are mentioned separately as well. as riparian / aquatic plants significantly influenced the ecological condition and the view of the lake, and there was a designed plantation as well, we analysed the situation of macrophytes in detail. the plantation of the lake was not completely assessable, the spectacular fluctuation of the water ecosystem could be expected for years (certain planted species lost ground, others appeared spontaneously) (table 4). based on observations done until now, yellow iris (iris pseudachorus) has been the most successful amongst the planted riparian plants. the spectacular late vernal bloom of the robust plants and the 100% remaining rate is a clear sign of its appropriateness. only a few stems of the flowering rush (butomus umbellatus) planting did not survive, therefore, these plants created a unified patch as well. dwarf bulrush (typha minima) has been planted in high numbers near the water obstacle course. the observations were ambivalent related to this species. plants completely perished on the south of the shallow bay, outside the flagstones, however the western side of the same patch was especially aesthetic, almost complete and in good health condition. plants planted on the north-west of the area showed a transitional image, here the stand was strongly scanty and imperfect (approximately 100 pcs remained of 192 pcs). in total, approximately 240 pcs of the planned 432 remained. table 2 characteristics of physico-chemical water quality, based on the samplings carried out in 2017 component 15 august 2017 30 august 2017 14 september 2017 flagstones ph 8.74 9.56 8.27 conductivity (µs/cm) 3860 3860 3620 dissolved oxygen (mg/l) 12.68 20.02 11.50 oxygen saturation (%) 154.4 266 127.7 water temperature (oc) 24.8 29.1 29.3 arched bridge ph 9.56 9.43 8.71 conductivity (µs/cm)) 3840 3840 3800 dissolved oxygen (mg/l) 21.38 19.82 8.39 oxygen saturation (%) 266.7 260 95.5 water temperature (oc) 25.9 28.4 20.6 22 boromisza et al. (2018) table 3 changes of wildlife between 2015-2017 2015 2016 2017 phytoplankton in may diatoms were dominating, especially navicula speciescwere characteristic. filamentous green algae (cladophora sp.) were also observed in different quantities. the bottom of the lakebed was covered by filamentous cyanobacteria. nitrogen fixing cyanobacteria became characteristic. in the first year of the operation scanty phytoplankton was characteristic of the lake, and the size of algae was also smaller than usual. we assume that the aftereffect of the disinfectant applied in the bath had impacted the lake’s phytoplankton. a few living diatoms (especially navicula sp., and nitzschia sp species) were present in may, and unicellular and thallophyte green algae were characteristic as well. filamentous green algae (chladophora sp.) developed massive amounts by the middle of the summer. in the summer of the third year, algae (especially euglenophytas) proliferated in a huge mass. in august 2017 200mg/m3 achlorophyll values were measured. part of the oxygen produced during the photosynthesis bubbled out of the water. there were few species with extremely high individuals in the samples. nitrogen fixing cyanobacteria were subdominant (especially anabaenopsis sp.), besides synechococcus sp., gomphosphaeria sp. and croococcus sp. cyanobacteria were also found. filamentous green algae (cladophora sp.) were also observable primarily in smaller patches. macrophytes a planned plantation was done. in some shore segments a spontaneously spreading, warmseason monocotyledonous weed, barnyard grass (echinochloa crus-galli) appeared in large quantities. besides the plantation some species started to spread spontaneously in the lake. from the planted vegetation, populations of water lilies (nymphea sp.), yellow iris (iris pseudachorus) and flowering rush (botomus umbellatus) remained almost completely. in the case of great manna grass (glyceria maxima) the rate of extinction was approximately 30%, in the case of dwarf bulrush (typha minima) approximately 50%, in the case of fringed water lily (nymphoides peltata) approximately 80%. a few stems of lesser bulrush (typha angustifolia), the first completely spontaneously growing riparian plants appeared in the shallow water. extensive patches of submersed aquatic plants (eurasian watermilfoil myriophyllum spicatum) fixed to the bottom were observable. the significant spreading was noticeable since spring. zooplankton the lake’s zooplankton was very scanty throughout the three years, the number of species as well as the biomass were remarkably low. protozoa and rotifers were dominating. the lake’s zooplankton was very scanty as well, with the domination of filtering organisms (daphnia sp., rotifers), predator zooplankton organisms were rarely found. ciliate protozoa were present in small number, rotifers were rarely found. usually the species structure of the zooplankton was scanty, its biomass was low. macroinvertebrates the first water bugs appeared, the several exuviae of adder-flies (odonata) were extremely noticeable on the stems of riparian plants. in general the number of macroinvertebrate species and their biomass were low. several exuviae of adder-flies (odonata) can be found on the stems of riparian plants like in the previous year. in the shallow water area larvae of mosquitos were not observable, however bloodworm larvae were found in one of the sludge samples. this functional group is scanty in general, representatives of many groups were missing completely. however the high number of dipterous larvae individuals is remarkable. vertebrates there was amphibian spawning in the first spring after the filling. adult fish were observed: common bleak (alburnus alburnus) individuals lived in the lake. several tadpoles and adult frogs belonging to different species were found near the shoreline. the appearance of a reptile species, the grass snake (natrix natrix) is a new finding. a red-eared slider (trachemys scripta elegans) were also seen during the fieldwork. fish were never introduced to the lake, in spite of this a fish population evolved. a mass fish die-off occurred killing 1,1t fish, especially common bleak (alburnus alburnus) and silver prussian carp (carassius auratus gibelio). https://hu.glosbe.com/en/hu/monocotyledons every start is challenging: fitting a new artificial lake into the landscape, zalakaros, hungary 23 the great manna grass (gliceria maxima) patch was slightly imperfect in 2016 as well. only narrow-leaved cattail (typha angustifolia) gave off shoots amongst the plants planted along the north shoreline. these were present on the shoreline in front of the “meditation space of the lights”, on both sides of the bridge, creating a continuous belt in visibly good health condition. by 2017 a significant expansion was observable of this species. on one hand, it reached the lake at the original plantation, on the other hand a spontaneous growth appeared in the obstacle course area. planted common read did not give off shoots, as it was planted by rhizome in the middle of july which is a not suitable period for planting reed. it was not inevitably necessary to replant this species. water lilies (nymphea sp.) were basically planted in three patches and they are the most outstanding eyemark of the lake. visibly they were in good health condition, and their continuous bloom also suggested that they found favourable conditions. especially the varieties with yellow flower were healthy. unfortunately, they were not expanding with adequate speed which might be caused by the algae growth. in the competition for light and nutrients between algae and seaweed, currently algae are in better position as the adequate macrophyte cover (30-40%) has not yet developed in the lake. unfortunately, the other floating leaf species planted near the water obstacle course, fringed water lily (nymphoides peltata) population suffered more, right now only a few stems could be discovered from the original planting. the assumable reason for the significant die-off is the unfavourable effect of the filamentous green algae (cladophora sp.) on the young fringed water lily individuals in 2016. floating seaweed hornwort (ceratophyllum sp.) did not remain in the lake either, currently it is not visible. in 2016 eurasian watermilfoil (myriophyllum spicatum) individuals were only visible in some areas, along the lake’s south shoreline. in 2017 this species spontaneously proliferated almost everywhere along the shoreline and near the obstacle course as well. in may 2016 barnyard grass (echinochloa crus-galli) was visible in places along the shoreline – due to maintenance these have already disappeared. the town management company carried out a smaller complement plantation on the lake in october 2016. 80 pcs of flowering rush (butomus umbellatus, 70 pcs of dwarf bulrush (typha minima) and 30 pcs of variegated reed sweet-grass (glyceria maxima „variegata“) were planted in order to complement the scanty vegetation. the aquatic macroinvertebrates indicate well the quality of the habitat, many organisms that can be used as indicators belong here. the autumn of 2017 was critical in terms of water quality therefore an assessment was done focusing especially on this group of organisms. 14 taxons were present in the thermal lake in total (table 5). only the empty carapaces of a mollusc species were detected in the water which indicates the still perceptible effects of the recent fish die-off (see under). curiously, many groups of invertebrates were completely missing: vermicules including leeches, mussels and snails, as well as crabs. above all, it was also ascertainable at the first sight that only adder-flies, true water bugs and diptera are present in the water. the most numerous group consisted of bloodworm and small true water bugs (micronecta sp., plea leachi). amongst adder-flies only three common species were detectable in the water. the most populated group was observed in the common area of the emersed and submersed aquatic plant stands, as here the most diverse microhabitat patterns could develop. the several recently leaved adder-fly exuviae on the stems of the narrow-leaved cattail (typha angustifolia) standing in water indicates that this type of environment offers an excellent habitat for these animals. it is ascertainable that the most diverse group consisted of true water bugs, as 8 from the discovered 14 taxons belonged here. however, regarding the population size diptera was the most numerous in the invertebrate group. in general, the organism group was scanty, species of many groups were completely missing, due to the unfavourable trend of water quality. on the other hand, the high number of dipterous larvae individuals stabilised in the lake was noteworthy. probably the reason for this is that the threat of the scarcity of direct dissolved oxygen has significantly decreased. although a regular oxygen supersaturation typical of hypertrophy occurs daily in the lake, probably oxygen is not consumed completely, as these creatures does not utilize atmospheric oxygen like true water bugs, but dissolved oxygen instead. this can be connected to table 4 alteration tendency of macrophyte species macrophyte species plantation method alteration tendency typha angustifolia by rhizome expansive typha minima by planting basket decreasing phragmites australis by rhizome didn’t take root glyceria maxima by planting basket decreasing iris pseudachorus by planting basket stable botomus umbellatus by planting basket stable nymphaea sp. by planting basket stable nymphoides peltata by planting basket decreasing myriophyllum spicatum by planting basket increasing 24 boromisza et al. (2018) their mass presence and the recent lack of significant fish population in the lake that could decrease the number of these animals by overgrazing. table 5 macroinvertebrate taxons found in the samplings in 2017 taxon sampling points 1 2 3 4 σ physella acuta 12 12 ischnura elegans pontica 19 11 6 17 53 anax imperator 12 9 3 24 orthetrum cancellatum 2 1 5 3 11 plea minutissima 67 12 22 10 111 callicorixa praeusta 1 1 corixinae gen. sp. 2 2 gerris sp. juv. 1 1 hesperocorixa linnaei 1 1 hesperocorixa sp. 3 3 micronecta sp. 36 5 12 8 61 sigara sp. 1 1 chironomidae gen. sp. 122 69 13 45 249 stratyomyidae gen. sp. 3 1 4 individual number in total 262 111 61 88 522 fig. 3 number of the discovered taxons/species in the three insect groups fig. 4 number of individuals in the three insect groups mass fish die-off occurred in the lake on 29 august 2017. it the phenomena more curious that there was no conscious fish introduction in the past three years, furthermore the lake bed was not connected to any natural surface water. the presence of fish was first observed in spring of 2016, and was also confirmed by a midsummer trial fishing in 2017. the die-off is significant in respect of lake maintenance and requires an extensive analysis. the several reasons for the perishing of approximately 1.1 t fish are concluded here:  prior the fish die-off filamentous green algae and nitrogen fixing cyanobacteria had proliferated significantly in the lake. as a result, an oxygen supersaturation had developed by the early afternoon, and part of the oxygen had bubbled out of the water. algae produces net oxygen during the day, but consumes oxygen at night, as they breathe as heterotrophic creatures in the water. on 29 august by dawn oxygen scarcity occurred which eradicated most (if not all) of the fish stock.  the heat experienced many times in august, with an average daily temperature above 25oc had contributed to the algae growth by causing the warming up the of the lake’s water. the solubility of the oxygen is inversely proportional to the water temperature, at the same time the oxygen consumption of heterotrophic creatures is directly proportional to it. consequently, the oxygen produced during the day had been consumed quickly at night (oxygen concentration under 3 mg/l is a danger to the fish stock). hypoxia was indicated by the aquatic surface respiration of fish.  chlorine tolerance of algae was low, most of them perished by 0.3-0.5 mg/l active chlorine. bleaching powder was not applied when it was recommended by the authors of the present study (19 august 2017), prior to the fish die-off. this could have slowed down the algae growth and could have decreased the oxygen consumption of the bacteria as well.  in the case of usual water supply the active chlorine present in the input water could have kept in check the phytoplankton. unfortunately, approximately two weeks before the end of august the input pump broke and only a low performance pump pumped the water to the lake. as a result, neither fresh water nor active chlorine were adequately supplemented and the phytoplankton association overgrew. the minimum one-month long average detention time was enough for this to occur.  a strong cold front reached western hungary by 29 august. living beings are also affected by fronts. according to an old observation, in case of certain type of fronts hypoxia occurs in lakes (especially in fishponds) at dawn, and if there is no possibility for artificial aeration the third or half of the stock perish. the same kind of cold front arrived at the end of august. it only reached western hungary and passed from south to north. 0 1 2 3 4 5 6 7 8 9 odonata heteroptera diptera n u m b e r o f d is c o v e r e d ta x o n s 0 50 100 150 200 250 300 odonata heteroptera diptera n u m b e r o f in d iv id u a ls every start is challenging: fitting a new artificial lake into the landscape, zalakaros, hungary 25 fish die-off occurred in many fishponds and lakes at the same time, for example tons of fish died in the lake kis-balaton. accordingly, the fish die-off at zalakaros was not only a local phenomenon. however, it could have been prevented (by applying bleaching powder and installing higher performance input pumps at the appearance of the expansive algae population).  the lake was strongly overpopulated by fish, few species were present in high individual numbers. this was partly responsible for the perishing of the zooplankton and the macroinvertebrate organisms. we did not assume that without introduction such a large biomass of fish could develop in the lake in three years.  probably most of the fish perished already on the 29 august, although most of the carcasses sank to the bottom. these only came up after a few days, as a result of the decomposition gases produced by the dead bodies. that is why aquatic surface respiration of fish was not observed in the next days. conclusions zalakaros town is well-known due to its thermal bath offering significant therapic value for many people, however, it lacks other free-time activities. this is compensated by the recently created artificial thermal lake, being under investigation in this study, due to its high aesthetical value and the connected recreational facilities. the artificial lake was a major challenge for the landscape architect as well as for the water quality specialist, as there were few experiences related to similar lakes. the unique characteristics of the lake are the high salinity, the significant concentration of well soluble salts, the low concentration of organic matter and plant nutriments, and the higher water temperature compared to other water-bodies of the nearby area. in the first years of operation the ecological tilting/sways caused extra work for both the maintenance and the consulting experts. as the new lake itself is an artificial-like element with ruined surfaces it was a fundamental aspect for us to naturalize it and to improve the diversity of habitats. the maintenance of the water quality and ecological condition requires regular and professional lake maintenance work, including the important tasks of operating the monitoring and treating the atypical phenomena. the newly created aquatic ecosystems can frequently change dramatically year to year (tilting or swaying). this is their normal behavior that can last 5 10 years. sways are still significant in the ecosystem of the thermal lake of zalakaros. the massive overpopulation of filamentous green algae in 2016 and filamentous green algae and cyanobacteria in 2017 caused problems. on the other hand, the macroinvertebrate group and the zooplankton had few species and small biomass in the lake. the reason for this requires further analysis. partly the algal growth but also the unlucky coincidence of other factors led to the die-off of the spontaneously overpopulated fish stock in 2017. this could have been decreased by certain interventions and adequate timing. however , it is probable that in few years the fish population will grow again in the lake, but this process should be regulated by colonizing predator fish in small numbers. plantation can prevent the plant nutriments to be absorbed by algae, instead of macrophytes. however, plantation is expensive, and in case adequate macrophyte cover cannot be reached, algae growth can cause serious water quality issues. keeping the water level low in spring in order for the macrophytes to grow up from the bottom can serve as an alternative solution. in spite of the numerous plants planted in this lake controlling the algae and the macrophytes have not succeed yet, as macrophytes require a long time to spread. besides the further plantations it is suggested to establish such built elements that enhance the lake’s attraction as well as the species and habitat diversity, and habitat complexity in the same time (e.g. man-made bird island, nesting holes). acknowledgements we render 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(1-2), 1–38. doi: 10.1016/0304-3800(94)90107-4 szilágyi, f. 2001. az eutrofizálódás és szabályozása. phd thesis, debreceni egyetem, debrecen. vinkó, t., szabados, k., kicosev, v. 2012. a palicsi-tó ökoszisztéma szolgáltatásai – híd a természetvédelmi szakma és a lakosság között (ecosytem services of lake palics – connection between nature conservation and the society). természetvédelmi közlemények 18, 526–536. wu, j. 2013. landscape sustainability science: ecosystem services and human well-being in changing landscapes. landscape ecology 28, 999–1023. doi: 10.1007/s10980-013-9894-9 introduction study area methods results evaluating the fitting into the landscape and the lake maintenance phyisico-chemical water quality changes of biota conclusions acknowledgements references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iv. no. 1-4. pp. 19-22 quantifying the geodiversity of a study area in the great hungarian plain őrsi, a. 1 1 geographical research institute, hungarian academy of sciences, budapest, hungary abstract geodiversity is understood as the diversity of the abiotic nature. it expresses the variety of stones, minerals, fossils, places, landforms, processes, soils and elements of hydrology. as geodiversity assessment is a rather new research area, the number of publications concerning geodiversity is growing fast. in this paper we quantified the geodiversity of a study area located at the danube-tisza interfluve in the great hungarian plain using the method worked out by hjort and luoto (2010). we wanted to know how the diversity varies in space at lowland areas applying different indexes. geodiversity was represented by three different indexes. total geodiversity was calculated by summarizing the geologic features, the landforms and the elements of hydrology found in each unit. then we grouped the landforms by the (exogenic) processes which formed them, and the number of these processes gave the value of the geomorphologic process diversity. finally we calculated the geodiversity index by serrano-canadas and ruiz-flano (2007). the absolutely homogenous units (totally waterlogged areas and the flat sand sheets) have the lowest geodiversity. it is higher at the border of the sandy, peaty and waterlogged areas. at this lowland area there is no relationship between the geodiversity and the relief. this is the first work applying this method in hungary, so the results are yet not comparable. introduction the objective of this paper is to quantify the geodiversity values of a study area located at the danube-tisza interfluve in the great hungarian plain using the method worked out by hort and luoto (2010). a further aim is to know how the diversity varies in space at lowland areas applying different indexes, which are the areas with lower and higher geodiversity values. we also intend to decide (if it is like hilly areas), whether the areas with diverse relief (sand dunes, deflation holes) have the highest geodiversity values or not. on hearing the word diversity most people think about biodiversity (the variety of the biotic nature), but geodiversity is an equivalent and inseparable part of the landscape, and one the premises of the development of biodiversity. geodiversity is understood as the diversity of the abiotic nature. it involves the variety of stones, minerals, fossils, places, landforms, processes, soils and the elements of hydrology. the term geodiversity is a new concept used since the middle of the 1990s. as geodiversity assessment is a new research topic, the number of publications concerning geodiversity is growing fast. new experiments are being carried out to quantify geodiversity. our approach is practice-oriented approach, which summarizing and quantifying the abiotic features (and their threats) found in the study area to support the development, tourism and conservation plans. according to geologists geodiversity means only geological diversity (keveiné bárány 2007, 2008), i.e. the variety of geological features, without involving other factors. it is stated in gray’s definition (gray 2004) that geodiversity includes the variety of geological features (stones, minerals, fossils), geomorphology (landforms and processes) and soils, as well as their assemblages properties, interpretations, systems and relationships. in the view of kozlowski (2004) geodiversity includes surface waters and the consequences of anthropogenic processes are equal with those of nature. the previous definitions were summarised and completed by serrano-canadas and ruiz-flano (2007): “geodiversity is the variability of abiotic nature, including lithological, tectonic, geomorphological, soil, hydrological, topographical elements and physical processes on the land surface and in the seas and oceans, together with systems generated by natural, endogenous and exogenous and human processes, which cover the diversity of particles, elements and sites.” another aspect focuses on examining the values of geodiversity which play an important role in determining the area independently from their distribution and frequency, instead of making a list of all of the elements found (panizza 2009). some studies (ruban 2010) evaluate the scientific or touristic values of geodiversity, their threats and possible ways of conservation. other studies regard geodiversity not as geomorphological heterogenity, but as the premise of biodiversity and focus on the variety of the conditions of life (jarvis 2005, parks – mulligan 2010, santucci 2005). these approaches search for relationships between the factors of the abiotic environment and the species diversity in relatively small study areas. using the revealed relations help to express the potential species diversity based on geodiversity without a detailed biodiversity monitoring. geodiversity investigations in larger areas aim to support development, tourism and conservation plans. in the beginning few experiences were made to quantify geodiversity. most of the authors supposed 20 őrsi, a. joeg iv/1-4 quantifying geodiversity, but only a few of them actually did it. it was kozlowski (2004) who first prepared a geodiversity atlas of poland, he assessed the geodiversity of his country at regional level. he scored 5 elements of geodiversity: geology, topography, soils, surface waters, and landscape structure separately on a five-degree scale ranging from very low to very high level. not only did he examine the amount of the features but also dealt with their quality such as the quality at surface waters. he also considered the influence of people on the landscape. the first and most popular geodiversity index was worked out by a team of scientists in spain. they computed the index values to geomorphological units. they took the abiotic features stock, filling a table with the present elements of geodiversity at every unit. the index value was calculated according to the following formula (serrano-canadas et al. 2009): gd= s reg ln * , where gd = geodiversity index, eg = number of the elements of geodiversity, r = roughness, here expresses the slope, s = area of the surface (km 2 ). the value of “eg” was calculated on the basis of the number of elements (lithology, geologic structure, morphostructure, landforms, processes, hydrology, soils) indicated in the tables. each element got one score, independently about its quantity in the unit. the variety of the topography and climate was represented with the roughness value, which was calculated with valuing the slope histograms. this influences the flow of energy and the intensity of the land forming processes. in this method the weight of the areas of the unit influences the index values more than it should, so the index values do not express the variety correctly (őrsi 2010). to eliminate the problem, finnish authors (hjort – luoto 2010) calculated geodiversity to areas of identical sizes using a grid network. they took the geological geomorphological and hydrological features into consideration. the authors expressed geodiversity with four different indices. total geodiversity was calculated by reviewing the stones, landforms and hydrological elements in each unit. landforms were grouped according to the processes, whose number gave the value of geomorphological process diversity. the units were categorized according to the number of the periods their surface was evolving, giving the temporal diversity value. finally, the previously mentioned geodiversity index by serrano-canadas et al. (2009) was computed. they also examined how relief affects the value of geodiversity. they used spearman rank correlation coefficients. none of the index values correlated with total geodiversity, although it seems that geodiversity is the highest on the steepest slopes. the probable reason is that the correlation between roughness and geodiversity is not linear. however, in spite of the weak correlations, they found that roughness is the highest in 90 percent of the units with highest geodiversity values. study area the study area is located around kiskőrös in the great hungarian plain (fig. 1). it belongs to the area of homokhát in bugac. it is a moderately undulating alluvial plain dissected by basins. the area ascends from nw to se. it is a transition from the floodplain of the danube to the higher lying part, i.e. to the ridge. the surface was formed by the danube, later it was reworked by wind. waterlogged areas, wetlands and peat vary with sand sheets and sand dunes. beside the dunes blowouts, deflation hollows make the area diverse. the wide shallow depressions used to be the channels of the danube, which lost the connection with the river as it was incising. the deposits of the higher lands accumulate here, those with less favourable drainage are covered by water during the whole year (szilárd 1955). methods the quantification of geodiversity was carried out by the method of hjort and luoto (2010). the whole area was divided into 500x500 m units. the geological, geomorphological and hydrological elements of the units were reviewed during our activities. the variety of the micro features was ignored because a survey would have been too complicated. we also neglected topography because the opinion of scientists is not unanimous about topography being and element of geodiversity. geodiversity is represented by three different indexes. total geodiversity was calculated by counting geological features, landforms and the elements of hydrology found in each unit. the categories of the detailed geomorphological map (juhász 2000) were simplified. table 1 shows the elements we took into consideration. then landforms were grouped according to the processes which formed them and the number of these processes gave the value of the geomorphological process diversity. calculating the values of temporal diversity does not make sense in this area because the surface has been forming since the pleistocene. this index was not treated separately, it was taken into consideration when calculating the geodiversity index. joeg iv/1-4 quantifying the geodiversity of a study area in the great hungarian plain 21 fig. 1 the study area table 1 the elements of geodiversity in the study area geology geomorphology hydrology quicksand flats in low position (intermittently waterlogged) lakes, intermittent lakes lime tuff flats between ridges in higher position swamps in the phase of uplifting clayey aleurit dry flats between ridges swampy flats, permanently waterlogged loess delllike depressions, deflation hollows flats intermittently waterlogged aleurit broad and level ridges in low position flats episodically affected by water narrow asymmetric ridges in low position ridges covered with wind-blown sand in intermediary position gently sloping ridges in higher position narrow asymmetric ridges, mounds extensive sand dunes, short ridges dunes wind furrows wind holes finally the geodiversity index by serrano-canadas et al. (2009) was calculated (see previous chapter). smaller modifications were carried out in the formula because of the same size of the units. the geodiversity index was calculated by the number of the elements multiplied by the roughness value. the calculation of the roughness value is based on the average slope angle the units. it was originally worked out by the spanish scientists for valuing the geodiversity of hilly and mountainous areas. as the slope of every unit is small on lowlands, the roughness of every unit is 1, say the number of the elements has to be multiplied with 1 when calculating the geodiversity index. according to the spanish authors a wider range of elements was included in the survey: not only geology, geomorphology, hydrology, but also soils and the date of formation were taken into account, however, anthropogenic forms were ignored.1: 100 000 geological maps, 1:10 000 geomorphological maps (juhász 2000) and 1:100 000 soil maps from the agrotopo database were used in the analysis. an elevation model has also been made based on the unified national map system (eotr) maps (1: 10 000) with 10 m pixel sizes and 1 m contour intervals. results first of all, it should be emphasized that these results (fig. 2) only inform us about the variation of geodiversity in this area. as no other attempt has been made in hungary up to now, the results cannot be compared with those of other areas. the values of total geodiversity in the 500 m x 500 m units vary from 2 to11, the average and the median values are 6. the values of 2-11 refer to the number of elements within each 500x500 m unit (see table 1). the geodiversity in the sand sheet in the ne part of the study area is smaller than the average. the homogenous units containing either only sand or only water have the smallest total geodiversity values. the highest values are at the units where sandy areas merge with wetlands. on the whole we can state that the southern part of the area (located a bit higher) has higher geodiversity values, but total geodiversity values do not follow the elevation values. in the lowland area only a few processes formed the landscape (the number of processes given by the finnish authors was nine). the value of geomorphic process diversity is 1 on the units totally covered by sand, 2, if there are wetlands in the unit and 3, where peat can be found, because besides wind and water, biogenic processes are also important. the values of the geodiversity index range from 5 to 11, the average is 17. this variation is similar to that of total geodiversity, but higher on the muskegs. no significant correlation could be identified between geodiversity and relief. 22 őrsi, a. joeg iv/1-4 conclusions the different explanations, representations and ways of quantifications of geodiversity were shown in this paper. the latest and probably the most detached method was applied on a lowland study area. the absolutely homogenous units (totally waterlogged areas and the flat sand sheets) have the lowest geodiversity values. the values are higher at the borders of the sandy, peaty and waterlogged areas. on this lowland area there is no relationship between geodiversity and relief. this is the first attempt to applying this method in hungary, so the results are not yet comparable. further research is needed on various landscapes for the identification of the applicability of the method. references gray m. 2004. geodiversity. valuing and conserving abiotic nature. chichester: john wiley & son. 434 p hjort j. – luoto m. 2010. geodiversity of high-latitude landscapes in northern finland. geomorphology 115/1-2: 109116 jarvis a. j. 2005. terrain controls on the distribution of tree species diversity and structure in tropical lowland and montane forest. london: king’s college. juhász á. 2000. kiskőrös természeti-ökológiai adottságai. budapest: mta földrajztudományi kutatóintézet keveiné bárány i. 2007. geodiverzitás a karsztokon. in: veress m. (ed.) karsztfejlődés xii. szombathely: bdf természetföldrajzi tanszék. 215-223 keveiné bárány i. 2008. geodiverzitás és tájdiverzitás. földrajzi közlemények 132: 431-439 kozlowski s. 2004. geodiversity: the concept and scope of geodiversity. przeglad geologiczny 52/8/2: 833-837 őrsi a. 2010. geodiverzitás-vizsgálat egy nyugat-bükki mintaterületen. in: kertész á. (ed.) tájökológiai kutatások. budapest: mta földrajztudományi kutatóintézet. 201-207 panizza m. 2009. the geomorphodiversity of the dolomites (italy): a key of geoheritage assessment. geoheritage 1: 33-42 parks k. – mulligan m. 2010. on the relationship between a resource based measure of geodiversity and broad scale biodiversity patterns. biodiversity conservation 19: 2751-2766 ruban d. a. 2010. quantification of geodiversity and its loss. proceedings of the geologists’ assotiation 121. 326-333 santucci v. l. 2005. historical perspectives on biodiversity and geodiversity. the george wright forum 22/3: 29-34 serrano canadas e. – ruiz-flano p. 2007. geodiversity: a theoretical and applied concept. geographica helvetia 62/3: 2-8 serrano canadas e. – ruiz-flano p. – arroyo p. 2009. geodiversity assessment in a rural landscape: tiermes-caracena area (soria). mem. descr. carta geol. d’it. 171-178 szilárd j. 1955. geomorfológiai megfigyelések kiskőrös és paks vidékén. földrajzi értesítő 4/3: 263-278 fig. 2 measures of geodiversity at a resolution of 500 x 500m 1. total geodiversity, 2. geomorphological process diversity, 3. geodiversity index. journal of env. geogr. vol. iii. no. 1-4. pp. 11-23 changes of landscape structure and soil production function since the 18th century in north-west saxony baude, m. 1 meyer, b. c. 2 1 institute of geography, university of leipzig, johannisallee 19a; 04103 leipzig; germany 2 tu dortmund, school of spatial planning, landscape ecology and landscape planning, august-schmidt-straße 10; 44227 dortmund; germany abstract the objectives of this paper are (1) to reconstruct time series of the historical and current landscape structures based on historical documents and serial cadastral maps, (2) to analyse the changes of agricultural production function by the application of historical soil assessments and (3) to analyse the connections between landscape structure and production function in reference to the social and economic driving forces. the case study area is today an intensively-used agricultural landscape located nearby taucha-eilenburg (nw-saxony), germany. arable landscapes in germany are changing with increasing dynamics: valuable structures and landscape functions of the traditional and multifunctional landscape were lost. new landscape structures replaced the traditional ones slowly or sometimes also in short time steps. therefore, this paper focuses on the changes of landscape structures and that of the soil production function induced by land use since the 18th century. the changes are analysed on the basis of historical and serial cadastral maps and documents by covering four time steps from 1750 to 2005. the historical maps were scanned, geo-referenced and digitalised in gis. thus, quantitative analysis of landscape structure changes on parcel level is enabled. the production function is explicitly reconstructed on the basis of the prussian taxation of the real estate of 1864 (preußische grundsteuerbonitierung) and the german soil taxation (reichsbodenschätzung) of 1937. changes observed on the serial cadastral maps were linked with the social and economical driving forces and the soil production function. moreover, there is a high demand for the development of methodologies to analyse and to assess time series of landscape structures, land use and landscape functions in the historical context of landscape development. keywords: landscape dynamics, landscape structure, production functions, soil assessment, gis 1. introduction from the end of the 18th century, social and economic changes had considerable influence on the landscape structure and the soil production function in europe. furthermore, land use changes result in less diverse landscapes and the degradation of landscape functions (antrop 2000). the long term process of structural changes leads to changes in usability of the landscape. landscape dynamics is intensively induced by natural and anthropogenic processes. landscape dynamics is defined as the changes of structure and function of a landscape that caused and steered by “driving forces”. “driving forces” are the whole of factors that influenced the development of landscape (bürgi et al. 2004). in case of the present study area anthropogenic processes are the main drivers of landscape dynamics. bastian and bernhardt (1993), and bernhardt and jäger (1985) reflect the anthropogenic impacts on landscapes in the investigated area in four time periods. the increasing impact of man on the landscape is described as nearly logarithmic in the following main periods: the neolithic revolution, the land use expansion in the middle ages, the industrialisation (19th century) and the scientific and technical era (since 1960). the landscape dynamics in historical time steps in the study area is discussed in this paper in the context of a today intensively-used agricultural region (krönert 1996). the aim is to support decision making for landscape and land use planning for a sustainable development in the future (antrop 2005, bastian – schreiber 1999, bender 1994, egli 1991, fehn 1986, marcucci 2000). bastian (1987) and bastian et al. (2002) stress the importance of the analysis of (historical) landscape dynamics to recognize negative landscape changes as soon as possible. furthermore, the documentation of historical economic time steps and the knowledge about recent cultural landscapes are important for the protection and the sustainable use of cultural heritage. in germany, similar to other european countries, the environmental law leads by several articles and political guidelines to the protection of cultural heritage (e.g. nature conservation act, environmental impact assessment act). the european landscape convention stresses the importance of the cultural dimension of landscape. moreover, longterm monitoring of landscape allows conclusions about the effectiveness of economic and political guidelines on a european level (e.g. on the natura 2000 network, common agricultural policy). landscape functions are defined as the goods and services from nature that provided by land use for human being (bastian – schreiber 1999: 38, de groot 1992, de groot et at. 2002). landscape functions can be categorised into four main groups: production functions, regulation functions, carrier functions and information functions (de groot 1992: 13). production functions in the focus of this study are economic functions describing the availability of renewable resources. it includes the production of vegetable as well as animal biomass (agricultural land, grassland, timber etc.), and water (drinking 12 baude, m. meyer, b. c. joeg iii/1-4 water, groundwater) (bastian – schreiber 1999: 39f). these productions functions are strongly related to the site conditions of arable lands and grasslands (as a function of climate, geology, slope, soil, water, the cultural technological history and the land use system). soils are also interpreted as the archive of historical impacts and results of the land use. the use of time series based on historical maps and land registers combined with historical documents is a common scientific method for the analysis of landscape dynamics and has proven to be very useful (bender et al. 2005, haase et al. 2007, ihse 1996). the study of land use changes and the quantitative analysis of time steps and time series are used to demonstrate how land use changes have influenced landscape structures and landscape functions in historical times. therefore, we ask how landscape structure has changed in the study area and what have been the main historic “driving forces” of the landscape dynamics observed? the other main question is how landscape dynamics has influenced the temporal changes of production function? subject, is the changing potential to biomass production by agricultural land use. soil as the basis of agricultural land use is evaluated in regard to the natural production by using of different governmental soil taxation results. the feedback of the soil as an archive to land use changes refer to the use of the (several) landscape functions (bork et al. 1998). these historic soil changes should be used in future landscape planning (beierkuhnlein 2002). the relation between landscape dynamics and production function will be discussed. as a conclusion, an overview is provided about the current and future values of historical landscape analysis. fig. 1 the study area (source: mannsfeld – richter 1995) joeg iii/1-4 changes of landscape structure and soil production function since the 18th century in north-west saxony 13 2. results 2.1. investigated area and data the study area (fig. 1) is located in the northeast of leipzig in nw-saxony, germany, as a part of the municipal region of jesewitz. the borders of the area are determined by the borders of the municipalities jesewitz, pehritzsch, weltewitz and wöllmen named in cadastral maps as “gemarkungen”. the study area is part of the natural region of the leipziger land. the area is characterized by precipitations between 550-600 mm/a and the average year temperature of 8.5 °c (mannsfeld – richter 1995). historical topographic maps provide a suitable cartographic database for the reconstruction of landscape structures. the present investigation is based on historical documents (landscape descriptions, local chronicles) and serial cadastral maps and data sheets from the 18th century and to the beginning of the 19th century (table 1). geographical information system (gis) was applied to analyse data and to visualise the results in maps. the quantitative analysis with gis needs first an examination to determine congruence and comparability between historical and modern maps (bender et al. 2005, neubert – walz 2002, walz et al. 2004). in this investigation maps of different scales and diverse content in geometry and legends are used. the “sächsische meilenblätter” (‘saxonian mile maps’) and the serial cadastral maps up to the time step of 1850 have been parallelised and adopted. thus, for oldest time step (1750) analysed in this study the geometry from the cadastral maps from time step of 1850 was used. the historical cadastral maps for time step 1850 were scanned, geo-referenced and digitalized on screen by using the gis-programme arcgis9. the information of the cadastral registers was adopted into attribute tables to generate a spatial explicit data set at ownership allotment level. the information of “saxonian mile maps” was overlaid by vector data of the time step of 1850. the data set and the attribute tables were adapted to the content of “saxonian mile maps”; and other information of historical documents and regional maps information was added. for the time steps 1950 and 2005 the vector data of the digital governmental cadastral map of ownership plots (automatisierte liegenschaftskarte, alk) were used. the data set for time step of 2005 have been integrated and revised by the author by field survey mapping in the year of 2005. the data set of the time step 1950 was adopted to the content of cadastral registers, survey maps; information has been added by the interpretation of aerial photographs of the year 1959. the development of field management practices since the 18th century in the study area is described for the assessment of production function. two soil assessment maps (1937 and 1864), originally produced for table 1 input data and data origin of the four time steps 1750, 1850, 1950 and 2005 time data source scale archive 1750 sächsische meilenblätter (1780-1811), dresdner ausgabe, bl. 21/30 1:12 000 hauptstaatsarchiv dresden petrikarten (ca.1760), bl. 1-2 1:33 000 institut für länderkunde, leipzig atlas augusteus (1722-1742), bl. 21 not known staatsarchiv leipzig schumannsches lexikon 1813(+) institut für länderkunde, leipzig geometries: urkatasterkarten 1864 staatliches vermessungsamt torgau 1850 geometries :urkatasterkarten (1864) 1:2500/1:3000 staatliches vermessungsamt torgau separationskarten (1810-1840) 1:2500/1:3000 landesarchiv wernigerode/ staatliches vermessungsamt torgau flurbücher des urkatasters staatliches vermessungsamt torgau 1950 liegenschaftskataster 1:2500 staatliches vermessungsamt torgau luftbilder (1959), 159/59/111-116 1:12 400 militärarchiv potsdam messtischblatt 1905-1912 (2609) 1:25 000 institut für länderkunde, leipzig geometries: automatisiert liegenschaftskarte (alk) staatliches vermessungsamt torgau 2005 geometries: alk 1:1000 staatliches vermessungsamt torgau own investigation note: in cursive: data source of the geometry for the time series. 14 baude, m. meyer, b. c. joeg iii/1-4 land taxation purposes, have been digitalized for the analysis of changes in natural soil productivity. the data sets were overlaid to the data layers described above in the gis. thus, a spatial explicit and quantitative analysis and comparison were enabled. the german soil inventory (1937) is available and documented for all agricultural and horticultural land in germany. sample points of this inventory are fixed in the soil inventory maps and detail described in inventory books (schätzungsbücher). today these data are stored and managed by the german local financial authorities. the data used in this case study is available from financial authority of eilenburg, nw-saxony. 2.2. time steps of land use development the land use categories applied for the comparison of the four historical time steps are arable land, grassland, forest, water bodies, settlement areas, and other land uses. furthermore, also the changes of the road network have been analysed (fig. 2). before the prussian agricultural reforms the hilly landscape of the study area was formed by glacial and periglacial landscape development since the saale glacial period. predominantly aeolian sediments of the earlier weichselian glacial period overlay sandy loess of periglacial origin by an average sediment layer of one meter. the sandy loess is the basis substrate for soil development. main soil types in the heterogeneous study area are lessivé and brown soils of medium suitability for agricultural production (meyer 1997). after the weichselian glacial period and several fluctuations including colder and warmer periods the study region was occupied by a more or less widespread forest of beech trees (fagus sylvatica) and oak trees (quercus). the first settlement activities in the study area are assumed for the palaeolithic time (dunkel 1969, 1977, hanitzsch 1956, 1962, moschkau 1957, töpfer 1958). lüning (1997) proved that settlements since the neolithic time are stable according their site location. at the end of the medieval period to the beginning of modern times (1500-1800 ad) the land use structure and the distribution of land use types were relatively stable (blaschke 1995). in the study area of a size of roughly 2.639 ha agricultural land still dominated in the time step 1750 by 1.938 ha or 73.4% of the total area. grassland covered 583 ha or 22.1% of the area. the other land use types are not of high significance by a percentage of 2.2% of forest, 1.1% of water bodies and 1.1% of settlement areas. the road network has been constructed since the medieval period of land colonisation with a length of approximately 34.1 m/ha (table 2). separation – changes in landscape structures in the 19th century political, social and economic influences particularly changed the landscape structure (rakow 2002). after the end of the napoleon era and the wiener congress (1815) the study area became a part of the prussian kingdom. induced by the napoleon wars, prussia had an economic crisis at this time. during the reformation of prussian agricultural management systems (1807-1850) a new land ownership allocation and land use distribution (so-called “separation”) emerged. the comparison of the time steps 1750 and 1850 results an increasing percentage of arable land from 73.4% to 86.0% in the area studied. grassland decreased of roundly 43% of the origin level. no dramatic changes occurred in the other land use types. forest and settlement area increased slightly, water bodies decreased slightly and land use type “others” remained at the same level. the road network increased from 34.1 m/ha to 35.8 m/ha (table 2). after the second world war in the middle of the 20th century the social and political situation changed dramatically. the land management practices have been mutated to the socialist planning regime of the german democratic republic (gdr) by following the russian soviet example. this organisation led to landscape structural changes with high impacts, for example, on flora and fauna water, soil, recreation or on the production potential of the landscape. traditional and diverse land use practices have been replaced by a new form of agriculture based on the intensive use of machinery and the increasing input of fertilisers (baessler – klotz 2006). table 2 percentages of land use types of the time steps 1750, 1850, 1950 and 2005 time step land use type arable land grassland forest water bodies settlement area other road ha % ha % ha % ha % ha % ha % m/ha 1750 1938.0 73.4 582.8 22.1 60.9 2.2 24.7 1.1 29.5 1.1 3.7 0.1 34.1 1850 2270.1 86.0 249.2 9.4 60.3 2.3 24.1 0.9 32.1 1.3 3.7 0.1 35.8 1950 2316.5 88.7 141.4 5.1 70.6 2.7 20.1 0.8 55.2 2.1 14.6 0.6 36.4 2005 2297.0 87.2 110.0 4.2 70.5 2.7 20.1 0.8 106.4 4.0 30.4 1.1 28.7 joeg iii/1-4 changes of landscape structure and soil production function since the 18th century in north-west saxony 15 fig. 2 landscape dynamics in the four time steps 1750, 1850, 1950 and 2005 (digitalisation and processing have been carried out by the authors) 16 baude, m. meyer, b. c. joeg iii/1-4 landscape changes since the middle of the 20th century two main steps of land transformation can be observed. in the first period until the 1950th grassland decreased with roundly 43%, and the arable land increased around 2% (1850=100%). at the same time, there was no significant change in the percentage of forest and water bodies. the settlement area increased with 72%. slight changes in the road network can be as well detected. however, the extensive management practices with multiple crop rotations and a lower level of techniques and fertilizer promoted a high biodiversity after the second world war until 1960 (baessler – klotz 2006). the second time step of 2005 shows that arable land has nearly the same amount as in the 1950th. nevertheless, grassland still decreased with 22% in comparison with the earlier time period. the intensification of agriculture by changing the landscape structure into very large-sized fields, the melioration, the irrigation and the application of pesticides and fertilisers have steered increases in food production over the past 50 years (matson et al. 1997). the road network was accommodated to the technical field management practices and decreased from 36.4 m/ha to 28.7 m/ha. since 1990 the total amount of land that used for agriculture is declining because of the impacts of the common agricultural policy of the european union by the promotion of set aside, and also due to market changes. additionally, intensive settlement activities of the urban sprawl of the city of leipzig have been observed since 1991. thus, settlement area increased from 55.2 ha to 106.4 ha, complies roundly 93%. the percentage of forest and water bodies remained on the same level. the decrease of land use type “others” since time step 1850 has been effected by the exploitation of sand and gravel (table 2). 2.3. comparison of the soil assessments of 1864 and 1937 in the middle of the 19th century the first soil assessment was executed in prussia by the order of the prussian law of real estate tax (“preußisches grundsteuergesetz”) from the 21st of may in 1861. the prussian taxation of real estate was based on soil attributes and economic values. the prussian taxation is distinguished in eight classes (fig. 3). the first class indicates soils with very good production services; class eight indicates soils with least production services. the high of classification tariffs (“klassifikationstarife”) for the eight several classes and various land use types (e.g. agricultural land, grassland) were determined by the local market situations (fig. 3, shown in elapse). thus, soils assessed in the first class have the highest tariffs and so on. the classes described the quality of natural soil fertility depend only on the natural soil attributes (without economic values). the prussian taxation of real estate was introduced in the study area around 1864. similarly, the sample points of this assessment have been extrapolated to the allotment level located in the cadastral maps of the year 1864. these maps also contain other soil parameters. the assessment level of natural productivity is classified in 8 levels of scoring. the soils evaluated into level 1 are of the highest natural productivity. for more details about the prussian law of real estate tax and their execution see amend (1997). in the study area the german soil inventory was introduced in the year 1937, according to the law from 1934 (bodenschätzungsgesetz). the german soil inventory database describes various soil parameters down to 1m depth. furthermore, there is also data on the geological origin, humus content, soil texture and other parameters (syrbe et al. 2007). the database divides the soil parameters and aggregates these different aspects into a scoring-index between 0 and 100. soils with the index of 100 are of the highest natural productivity in germany (e.g. magdeburger börde). for the comparison the soil numbers (soil numbers between 0-100; soil with soil number 100 have the most natural soil fertility) were used. the explicit description of the methodology of the soil assessment comparison is demonstrated by baude and meyer (2006). in figure 4 the distribution of the prussian soil assessment in the study area is presented. the borders between the classes from classification tariffs of the fig. 3 classification tariffs for the study area (source: staatliches vermessungsamt torgau) joeg iii/1-4 changes of landscape structure and soil production function since the 18th century in north-west saxony 17 prussian taxation were oriented according to the field borders on ownership allotment level. within these fields plots of the same classification can be found. there is no specific exploitation raster. the soil taxation correlated with the field on ownership allotment level. the prussian taxation shows the natural character of suitability for fig. 4 prussian soil assessment from 1864 (digitalisation and processing were carried out by the authors) fig. 5 german soil inventory from 1937 (digitalisation and processing were carried out by the authors) 18 baude, m. meyer, b. c. joeg iii/1-4 agricultural production, because melioration and fertilization started later, with the industrialisation, after the prussian taxation. the differentiation in the map of the german soil inventory (in fig. 5) is effected by the exploitation in raster 50x50 m. furthermore, the extended soil exploitation distinguished 31 soil types with several soil characteristics. thus, the characterisation of the different soil characteristics is enabled. although the approach used for the analysis of the german soil inventory (1937) has been adapted on the soil assessment of the year 1864, the different data sets cannot be compared without 1:1 gis-adaptation (freund 1998). thus, for the comparison of the two different soil assessments we applied a generalization of the data of german soil inventory. the differentiated data set of the german soil inventory (1937) were first summarized to five main groups according to the soil numbers and assigned to the “grouping of usability” (‘nutzbarkeitsgruppen’) (matz 1956). the grouping composited the soil number according to the soil type. in this case there are five groups of usability with the associated soil numbers. furthermore, the classification tariffs were composite to five main groups according to the level of their taxation class and assigned to the “grouping of usability” as well (table 3). this generalization provides a methodology to compare the two soil assessments based on a more summarised character of the different data sets. the comparison based on gis-analysis of land which was used as arable land between the time periods 1850 and 2005. a quantities analyses of the changes of the soil characters between 1864 (prussian taxation) and 1937 (german soil inventory) is applied. validity of results of the german soil inventory is applicable to describe the current soil characters when the actual morphological dynamics are integrated (finke 1994). the comparison permitted that 97.7% of the comparable agricultural land can be ranged in five groups. table 3 shows that the second group of usability dominated in both soil assessments with 66.6% (gsi) respectively with 83.72% (pt). in group 3 there are 22.9% (gsi) respectively 14.07% (pt) of comparable agricultural land. thus, a significant part of the agricultural land can be associated to the groups 2 and 3. the groups 1, 4 and 5 are without a higher importance for the soil assessments and described 10.5% (gsi) respectively 2.21% (pt) of the comparable agricultural land. 3. discussion 3.1. interpretation of historic maps and soil taxation the spatial explicit mapping of landscape structural changes is accompanied with uncertainties concerning scales and contents of the information included. the landscape dynamics analysed in the time steps and the interpretation of their impacts on structure and function of recent landscapes should be seen on the background of historical data sets and maps. historical landscape analyses on the basis of gis data offer new views for the knowledge about dynamics, structure and functions of landscapes. long time series permit landscape assessments of changes related to economic, ecological and social aspects. with regard to their validity historical data sources must be critically checked. while the scale of the data set makes the exact reconstruction difficult, the knowledge about the landscape functioning in the past is very useful to understand recent processes of landscape changes. in our study, land use changes and the quantitative analysis of time steps are used to demonstrate how land use changes influenced landscape structures and landscape functions. therefore, we ask how landscape structure has changed in the study area and what have been the main historic “driving forces” of the landscape dynamics observed? the other main question is how landscape dynamics has influenced the production function during time? table 3 comparison of german soil inventory (gsi) and prussian taxation of real estate (pt) soil number classification tariffs grouping of usability is/sl 1 gsi in ha pt in ha gsi in % pt in % arable land 1 64-81(+) 85.8 43 4.09 2.05 1/2 2 49-63 1395.7 1752.9 66.6 83.72 3/4 3 36-48 480 294.6 22.9 14.07 5/6 4 29-35 53.2 3.2 2.54 0.16 7 5 (-)18-28 81.1 0.05 3.87 0 8 sum 2095.8 2093.8 100 100 1 main soil type of case study area joeg iii/1-4 changes of landscape structure and soil production function since the 18th century in north-west saxony 19 in the following chapter, we discuss shortly how the landscape has developed since the neolithic. starting with the beginning of the prussian agricultural reforms we analysed four time steps in the context of the main drivers of landscape change. we proved two periods in change of the production functions in regard to the main driving forces. 3.2. land use changes in the context of driving forces the first permanent settlements of the study area in the neolithic revolution were accompanied by the first strong human influences of the landscape. during this period the cultural landscape usage began with common forest pasture and led to first deforestations. however, after this first deforestation began a reforestation period until the slavic colonisation during the migration period in the 6th century (gringmuth – dallmer 1983, bork et. al. 1998). thus, the human impacts of neolithic revolution were without high importance. the first major landscape changes caused by the slavic colonisation associated with population growth and an increase on cultural land use. after the beginnings of the colonisation by german settlers, the so called 'east expansion' in the 10th century, the population grew up to decuple. the agricultural land increased in according to further land use practices to a first maximum in the 14th century. during the 'east expansion' the landscape structures changed dramatically. until the end of the middle ages the indigenous forest area decreased by 90%. at that time arable land became the dominant land use type. blaschke (1995) and nitz (1995) proved that the distribution of land use types in the study area has not changed after the end of the middle ages. however, with the prussian agricultural reforms the landscape structures changed again distinctly. our spatial explicit analysis, starting in the middle of the 18th century, results that arable land increased significantly at the begin of the 19th century. up to the middle of this century until today the land use type distribution was relatively stable, when compared with large land cover changes e.g. in estonia (mander – palang 1994). the area of grasslands decreases in our investigation area continuously; forests and water bodies are normally stable, located on the same plots, the area for settlements increased slightly. the linear infrastructure changed with the separation by the new property situation and the needs for new agricultural methods. the development in the 19th century coursed mainly by the prussian agricultural revolution, when the economic situation after the napoleon wars were disastrous and new field management and practices were needed. in the course of the “collectivisation” in the years between 1950 and 1960 the linear infrastructure changed dramatically, when several paths and country roads have been deteriorated and most of the field margins and hedges were destroyed to arrange the countryside in the of form of large field plots for mechanised crop production. furthermore, another main development period was initiated by the gdr government to copy the russian kolkhoz system to germany. the extension of mechanical and chemical agricultural practices needed large field sizes and less linear infrastructure inside the fields. the heterogeneous agricultural landscape, structured until the 1960s, has been diverted into a homogeneous and intensively-used mono-functional agricultural landscape without clear cultural orientation and coupling the formally agricultural villages. the development of land use types depends on several driving forces: in the past natural hazards such as extreme weather and intensive rains with high impact on the landscape have changed the land use (bork et al. 1998). furthermore, landscape structure changes were influenced by social and political events like medieval diseases, wars (thirty years' war, 1st and 2nd world war) and economic crisis (e.g. the agricultural crises at the beginning of 19th century, the collapse of agriculture after world war 2). there are several public reformations such as the prussian agricultural revolution in the 19th century or the planning economy of former german democratic republic which have also influenced the development. today eu-norms and regulations steer the development of landscape structures, i.e. by the common agricultural policy, the habitats directive and natura 2000 network. 3.3. soil productivity changes knowledge for sustainable land use the production function in the study area is mainly characterised by the agrarian productivity. thus, this agrarian productivity depends on natural soil productivity in addition to the soil characteristics. in the period between the slavic colonisation and the beginning of the prussian agricultural revolution and the industrialisation in the second half of 19th century the agrarian productivity depended mainly on the expansion of agricultural land. the expansion of agricultural land came to an upper limit when the best lands were cultivated (mottek 1987). to the beginning of the prussian agricultural revolution the growth of production function is also steered by the expansion of agricultural land use. the maximum of agricultural land is achieved. the beginning of the industrialisation defined that the growth of agrarian productivity based as of now on new technical achieve20 baude, m. meyer, b. c. joeg iii/1-4 ments, modern management practices and the expansion of new mineral fertilizer (müller 1998). the intensity of agrarian productivity became a new dimension after the “collectivisation” around the 1960th. the new farm management system with large field sizes and technical field management practices, and also the intensive melioration of water households lead to a significant growth of production. jäger (1987) proved that the main growth of production function was between 1950 and 1980. körschens et al. (1994) identified in according to jäger (1987) an increase of grain production with 100% between 1902 and 1992. however, these practices of intensively-used agricultural land led to strong impacts in soil and groundwater ecology because of soil erosion and soil degradation. bork et al. (1998) postulated for the same time period the increase of soil erosion and soil degradation in several other european regions as well. in order to clarify the situation of the soil productivity function, the prussian taxation of real estate (1864) and the german soil inventory from 1937 give the soil and land use status before and without the intensive changes from extensive use to intensively-used agricultural land in the second half of the 20th century. however, the comparison of the two soil assessments by this study indicates steps of change. the natural soil productivity decreased to a larger area of soil in a lower group of usability (table 3). we distinguish two main periods of the production function development in the investigated area during the last 150 years. we found a first period from 1864 to 1960 with relative stability in comparison to other phases since the middle of 18th century. the distribution of land use types was stable and the changes in natural soil productivity in accordance with the investigated soil assessments were without high amplitude (jäger 1987). the second active period up to 1960 were characterized by new management practices like melioration, fertilisation and mechanical soil management (jäger 1987). the increase of the production function (e. g. in the production of cereals) is accompanied with the degradation of natural potential to produce biomass on several fields, because of erosion, soil accumulation, soil compaction and other changes of physical and chemical soil characteristics. to conclude the comparison of the two soil assessments we can say that the natural soil productivity has not significantly changed between the middle of the 19th century and the beginning of the collectivisation (1960). figure 6 shows the development of natural productivity and the crop production. furthermore, the main driving forces that influenced this development were shown in context of the time scale. the increasing landscape dynamics by land use practices and land use changes are in the same time essentially for the development of the production function. fig. 6 development of production function according to main driving forces, legend: p+ö=pestilence and ecological changes, 30k=thirty years’ war, pg=prussian taxation, rbs=german soil inventory, wk=world wars i / ii, br=gdr agricultural reform, v=gdr “collectivisation”, eu=european agricultural policy joeg iii/1-4 changes of landscape structure and soil production function since the 18th century in north-west saxony 21 the changes in management practices and the new agrarian objectives of the society have strong influences on the production function. the result of these developments is a highly productive agricultural land use. the adaptation of the landscape structure and the monofunctional land use by preference of the production function is the result of the economic optimisation. this economically optimised land use recently goes on with the ongoing height human input of energy and substances. thus, the today’s stability of the production function depends directly and mainly on the inputs of the farmers. it follows that the ecological equilibrium of the manmanaged land is increasingly unstable and vulnerable against such disturbances as natural hazards (steinhardt 2005). dabbert (1994) points to the enhanced organic management practices developed in modern agriculture with nutrient balances and increasing soil fertility since the 19th century. meyer (1997) proved for the investigated study area that the regulation functions as a term of the landscape household of landscapes is still in decline from the collectivisation period. the biodiversity heavily decreased after the “collectivisation” by the intensively-used agricultural land and the changes of landscape structure (waldhardt et al. 2003, baessler – klotz 2006). in comparison with that the less intensive agricultural land use directly after word war ii promoted high spatial heterogeneity and the richness species (baessler – klotz 2006). the biodiversity increase is described for the time period until the mid-19th century for cultural landscape followed by a decrease since the beginning of industrialisation of agriculture (plachter 2001). 4. conclusion similar to most european countries, the landscape structure changes described in this study follow the comparable fundamental changes especially for the time period after 1960. landscape structural changes and the development of production function should be seen and combined with results of other disciplines like the studies on climate change, the investigations about the loss of biodiversity, the degradation of arable land and the desertification problem. furthermore, the results show the linkage between human land use, and landscape structures and functions. the interdependency between landscape structural changes and the development of production function is also demonstrated in this case study. followup impairments, for example soil degradation, soil erosion and the total loss of soil productivity, the society will confront with economic, ecological and social problems with probably high costs. thus, for a target-oriented, based on the principles of sustainability and landscape functions to produce ecosystem services land use planning, the historical information demonstrated in this study can help to bridge the gap between economic and ecological interests. aspects of historical land management practices confront the discussion with examples how to manage the landscape and that the satisfaction of human needs can be brought in line with ecological interests. this balance between human productive needs and techniques, and the ecological basis is necessary for a sustainable future. the methods to analyse the changes of landscape structure and soil production function induced by land use since the 18th century in north saxony demonstrated in this study should help to bring the historical 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(eds.). historische landnutzung im thüringisch-sächsischanhaltinischen raum. tagungsband. frankfurt/main: peter lang verlag steinhardt u. 2005. mensch und natur – gedanken zum landschaftsbild und zum umgang mit landschaft. http://www.tucottbus.de/btu/fak2/theoarch/wolke/deu/th emen/992/steinhardt/steinhardt1.html (22 december 2005) syrbe r.-u. – bastian o. – röder m. – james p. 2007. a framework for monitoring landscape functions: the saxon academy landscape monitoring approach (salma), exemplified by soil investigations in the kleine spree floodplain (saxony, germany). landscape and urban planning 79: 190-199 waldhardt r. – simmering d. – albrecht h. 2003. floristic diversity at the habitat scale in agricultural landscapes of central europe – summary, conclusions and perspectives. agriculture, ecosystems and environment 98: 79-85 walz u. – neubert m. – haase d. – rosenberg m. 2004. sächsische landschaften im wandel. auswertung historischer kartenwerke für umweltwissenschaftliche fragestellungen. europa regional 11: 126-136 töpfer v. 1958. steingeräte und palökologie der mittelpaläolithischen fundstelle rabutz bei halle (saale). jahresschrift für mitteldeutsche vorgeschichte 41(42): 140-177 sensitivity analysis for effect of changes in input data on hydrological parameters and water balance components in the catchment area of hungarian lowland journal of environmental geography 14 (3–4), 1–13. doi: 10.2478/jengeo-2021-0007 issn 2060-467x sensitivity analysis for effect of changes in input data on hydrological parameters and water balance components in the catchment area of hungarian lowland hop quang tran1*,2 1department of geoinformatics, physical and environmental geography, university of szeged, egyetem u. 2-6, 6722 szeged, hungary 2hanoi university of natural resources and environment, faculty of water resources, hanoi, vietnam *corresponding author, email: hoptran@geo.u-szeged.hu, tel.: +36 30 179 9296 research article, received 1 april 2021, accepted 7 september 2021 abstract extreme weather and climate changes are emerging more frequently in central europe, hungary, and in the near future the increase in prolonged droughts, high-intensity precipitation events and the temporal variations of precipitation are expected, which may increase the magnitude of local water damages (ovf, 2016). as a result of climate change, these extreme weather events will be more frequent, however it is difficult to predict them, as until now insufficient amount of observations are available on smaller watercourses and on refined territorial water balances. for the future assessment of the environmental and economic impacts of climate change, it is essential to explore the integrated relationship of evapotranspiration, runoff, infiltration, surface and subsurface waters, and other hydrological processes, which can fundamentally describe regionally the water management conditions. in this research, an earlier study (dhi hungary 2019) on the catchment area of the main canal of the dong-ér brook is pursued to continue the development of the mike she model in a more complex manner. within the frame of the present study, the relationship between the individual hydrological parameters, the water balance components and extreme precipitation events (drought, heavy rainfall events) for the entire drainage basin have been examined, besides, the expected effects of the predicted temperature rise on the water balance is evaluated. using data from 2018 as reference, the sensitivity of the changes in daily precipitation and daily mean temperature has been assessed to estimate the effects of the future climate change on hydrological parameters and water balance components. keywords: dong-ér brook, mike she, sensitivity analysis, water balance introduction water management is playing an increasingly important role in mitigating the effects of the extreme climate changes. based on lower tisza district water directorate (ativizig) data in hungary nearly 1100 settlements over about 42000 km2 area occasionally struggle with severe inland water problems (ativizig, 2016). general directorate of water management (ovf) emphasizes that as result of climate change, extreme weather events are becoming more frequent in hungary, and soon an increase in the regularity of high-intensity precipitation events should be expected, which may increase the magnitude of local water damages (ovf, 2016). extreme climatic events are also reflected in the phenomenon of drought, with a longer degree, intensity and duration. according to the survey results in south hungary by ladányi et al. (2014) water shortage was more damaging than inland water. consequently, the changing climatic effects have a direct impact on agriculture, causing greater damages mainly due to the droughts and directly affect the sustainable development of agriculture and food security (singh, 2014, ladányi, 2010). due to climate change, precipitation has decreased by at least 12% in recent decades in hungary, with perhaps the most significant consequences on the danube–tisza interfluve (ladányi, 2009), where the study area is located. according to the experiences, harmful water scarcity occurs in an average of 4 years per decade in hungary. at the same time varying amounts of excess water occurs in most years, while it is not even uncommon for the two extremes to occur in the same year, such as between the danube and the tisza in 2000 (rakonczai et al., 2014). an integrated approach is necessary to evaluate the complex interrelationships of hydrological processes and changes in water balance from many aspects, thus provide effective solutions for the complex modelling challenges in the presence of both inland excess water and drought. the topic is well introduced by the tisza river basin management plan (kötivizig, 2015). as a result of the developments in the information technology, the application of the geographical information system (gis) and various mathematicaland physical-based hydrological modelling software has also become feasible for related research. among the many models, the mike she model emerges as a tool capable of implementing integrated water resources management. the model tends to effectively simulate the interaction between surface water and groundwater (graham and mailto:hoptran@geo.u-szeged.hu 2 tran 2021 / journal of environmental geography 14 (3–4), 1–13. butts, 2005). the research group of lu et al. (2006) also had positive comments about the effectiveness of the model in simulating temporal flow dynamics in the whole basin. mike she is widely used in studies such as calculating the effect of land use changes on components of water balance in the unsaturated zone (uz) and saturated zone (sz) (asadusjjaman and farnaz, 2014). some studies apply mike she and gis to simulate hydrological processes for several basins (paparrizos and maris, 2015; právetz et al., 2015) and assessing the effects of land change and climate change on groundwater and ecosystem by keilholz et al. (2015). among the hydrological models that have been verified on the catchment area of the fehértó-majsa canal, which is located next to the dong-er catchment to the south by benyhe et al. (2015) include budyko, hec-ras and mike she and concluded that the mike she model was more efficient than the other two. the process of modelling inland excess water with mike she and using satellite imagery for validation by van leeuwen et al. (2016) is another example showing the effectiveness of the mike she model to predict the extent, location and duration of inland excess water. the research team of nagy et al. (2019) built a mike she model to simulate the accumulation processes of excess water, water storage, and excess water maps for dong-ér catchment and have very remarkable results. however, the above studies also have shown a disadvantage of this model is that it requires many good quality input data. in dong-ér catchment, the data is not continuously measured, there is no data for water level and discharge in the open channels, and many parameters are not validated (e.g. lai, root depth. hydraulic conductivity). nagy et al. (2019) has calibrated the model focused on the groundwater levels for 2015 and 2018-years' springtime. the comparison between the modelled and measured groundwater level is 45 cm, which is very relevant considering the lack of input parameters and the uncertainties. this result shows that the integrated mike she model built for the dong-ér catchment has been relatively calibrated and can be inherited to calculate and analyse many other aspects of hydrology in the relationship between surface water and groundwater. in such areas where inland excess water and drought are both affects the landscape heavily, understanding the state of the water balance becomes even more imperative. importance of management, planning and optimal consumption of water resources more effectively and sustainably is even more crucial (eu water framework directive, 2000; ovf, 2009). sipos and právecz (2014) stated that only the local water balance models can be considered reliable in order to make efficient and economically sustainable water use options in the dry season and water retention in the rainy season. one of the advantages of mike she is that it includes a comprehensive, integrated water balance tool for the complete local and entire catchment water balance for any time interval. water balance output can include area flows, storage changes and water balance changes (dhi, 2017). the total water balance change value is calculated for the entire model catchment. in addition, there are water balance changes for each hydrologic component. however, within the scope of this study, only the variation of total water balance change under different climatic conditions are considered, analyzed and evaluated. the value of these parameters plays an important role as the foundation for assessing the water balance in the dong-ér catchment. it is useful for integrating, mapping and plotting water flow processes between water balance components (graham and butts, 2005). there are many factors that affect directly and indirectly on the water balance of a basin, the first of which is precipitation and temperature. they are the two main forces that operate the hydrologic cycle and have a major impact on water balance. the question is how changes in inputs due to climate change affect the outputs of hydrological parameters and water balance components. according to the studies of hamby (1994) and lenhart et al. (2002) the variation in the input data causes effects on the model results and it is necessary to consider the sensitivity of the input data and apply the sensitivity analysis method to determine which inputs have the greatest influence on the outputs. ibarra et al. (2016) confirmed that setting up sensitivity analysis is necessary to improve the accuracy and optimize the calibration process. besides, the sensitivity analysis enables the estimation of the parameters and explains the response of the model for the variation of the input data. the objective of the study is to simulate different climate conditions and use sensitivity analysis to evaluate the influence of input parameters on hydrological parameters and water balance components. however, to perform these integration tasks, mike she needs a lot of hydrological and meteorological data input (van leeuwen et al., 2016) and especially difficult for areas with few data such as dong-ér catchment. deterministic models have uncertainties, these include reasons such as measurement errors, variation of parameters on the subgrid scale and incorrect initial, boundary conditions (graham and butts, 2005). bahremnad and de smedt (2007) also highlighted sensitivity analysis as a valuable tool to identify influential model parameters and thereby make the model structure more stable. there are many methods of sensitivity analysis that have been used in the international literature, most of them are very complex and the simplest approach to conceptualize is the one-ata-time method where sensitivity measures are determined by varying each parameter independently while keeping all other parameters do not change. the disadvantage that it can only do local sensitivity analysis at a certain selected point and not for the entire parameter distribution (hamby, 1994). however, with the flexible simulation framework on spatial and temporal scale of the mike she model, this disadvantage can be improved and gives us an integrated view and more comprehensive. to understand the hydrological phenomena that will occur in the future, this study inherits the mike she data tree built by nagy et al. (2019). however, to apply the one-ata-time method, the variable parameters and the water calculation module has been developed and used by author to simulate and evaluate with an integrated approach which manifestation of climate change has the greater impact to the outputs of the hydrological parameters and water balance components. to achieve tran 2021 / journal of environmental geography 14 (3–4), 1–13. 3 these objectives, it is necessary to 1) review the suitability, determining the advantages and disadvantages of the mike she model for dong-ér catchment, 2) simulate hydrological and complex water balance processes under different input variable conditions, 3) simulation results are compared to see which factors are most affected and most sensitive to variations in input data. based on this result, evaluate the effects of climate change on hydrological parameters and water balance components in the future. study area the inland water system of the dong-ér brook is in the middle part of the sand ridge region of the danube-tisza interfluve, about 50 km from the southern border of hungary (fig. 1). the total area of the catchment is 2127 km2, and it is characterized by a small relative relief (<2m/km2). in the initial section of the dong-ér brook the surface water transport is minimal, the occasionally drying riverbed is revealed only by the vegetation of wetlands. therefore, water resources of this area are not suitable for utilization, rather the use of groundwater resources comes to the fore (kozák, 2020). the system of small brooks collects and carries excess water into the main dong-ér brook and then flows into the tisza river near the settlement of baks. the gravitational flow terminates only in the case of the formation of an extreme tisza flood wave. the discharge of the dong-ér brook is 2-3 m3/s during the normal period, meanwhile in times of spring inland excess water it can excess 20-30 m3/s. however, in extremely dry summer days, the brooks dry out completely (k&k mérnöki iroda kft, 2013). prevailing wind direction nw, average wind speed about 2-3 m/s. the surface-forming activity of the wind shaped the topography. the topography of the area basically defines the water networks. the flow direction of the dong-ér is sw-ne, while the flow direction of the tributaries is nw-se, typically follows natural deflationary depressions. in rainy years, groundwater can appear in the deflation hollows, forming temporarily inundated areas (sipos and právecz, 2014). based on studies conducted by the hungarian meteorological service (2018) with two regional climate models and two scenarios, the average temperature in hungary may increase by 3-4˚c by the end of the century and the 2˚c threshold is expected to reach earlier. dongér catchment is one of the warmest and driest areas. therefore, the drought hazard is high in the area (sipos and právecz, 2014). the area under investigation is dry continental temperate climate. according to the data from hungarian meteorological service (omsz) and from 25 available meteorological stations between 2010 and 2018, the average annual rainfall in the area over the period is 611 mm, but in extreme cases it can reach as high values as 842 mm (in 2014) or as low as 203 mm (2000). during the period between 2000 and 2018, the lowest monthly mean temperature was -5.2°c measured in february 2012 and january 2017, the highest was +24.5°c measured in august 2018. the average thickness of the snow cover in winter is about 18-22 cm. the most frequently mentioned feature of climate change is rising temperatures. according to the climate models adopted by the intergovernmental panel on climate change (ipcc, 2018), the average temperature of the earth could reach an increase of 1.5˚c in 2030-2052. fig. 1 the study area 4 tran 2021 / journal of environmental geography 14 (3–4), 1–13. non-irrigated arable land dominates the area by ~41%, followed by pastures ~13%, by broad-leaved forest ~10% of the total study site, the rest are various small land uses, like transitional woodland-shrub, complex cultivation patterns, discontinuous urban fabric. based on the available agrotopographic map, the soils in the area are extremely heterogeneous. the most typical soil types are blown sand, humid sand, sandy soils, chernozem and saline soils. these soils have the potential to infiltrate. since the late 1970s, the decreasing trend of the precipitation induced significant decrease of the groundwater level in the danube–tisza interfluve, which exceeds 2 meters on average (fehér, 2019). afterwards, in the periods of persistent precipitation, water shortages in the lower parts of the sand ridge have been restored; in fact, sometimes the groundwater level has risen to harmful level, causing surface overflows (szatmári and van leeuwen, 2013). data and methods input data used in the model meteorological data the most important meteorological data in a hydrological cycle are precipitation, temperature and evapotranspiration. for the observed precipitation in study area, the daily data of 25 meteorological stations was available in the period 2010-2018 from ativizig. according to this, the average monthly precipitation of the study area varies around 46 mm. according to the omsz (2018a) database, in the drought year of 2000, about half of the average monthly precipitation (29 mm) was measurable in szeged, but some extreme years, such as the 2014 rainy year, also occurred in 89 mm in the study area. snow storage is a physical state of precipitation and differs from the rainfall form in the time of accumulation, so participate more slowly in the water cycle. temperature is a factor that can accelerate water accumulation through melting. temperature also affects directly (e.g., pond water evaporation, soil evaporation) and indirectly (transpiration by vegetation) on evapotranspiration. as a result of temperature fluctuations, several important climatic elements change, and these greatly affect the water balance of the area. temperature data for 2014 and 2018 are taken from the european climate assessment and dataset (ecad) database for the period 2010-2018 by nagy et al. (2019). daily average temperature data for the year 2000 are obtained from the omsz (2018a) database by author. evapotranspiration is the most difficult parameter to determine and there are no data in the study area. to calculate the amount of evapotranspiration the food and agriculture organization of the united nations (fao) recommends a combination of the fao-56 penmanmonteith equations (allen et al., 1998). due to the lack of input data, the use of the fao-56 penman-monteith equation is limited. the potential evapotranspiration (etp) can still be estimated more easily and simply by the function for different temperature (t) values, to which the following exponential function describes the relationship well (fiala et al., 2018): 0.07t p ref et et e  (1) land cover data the current modelling framework identified 23 different land use classes. each class has different characteristics of canopy interception, transpiration, soil evaporation, flow formation, and different water retention ability by roots. the research is based on the corine land cover (eea, 2018), the de facto standard for land use and land cover monitoring at the pan-european level (feranec, 2016; aune-lundberg and geir-harald, 2020). the leaf area index (lai) is determined by the combination of modis images (myneni et al., 2015) and root depth values are referenced from the results of scientific studies for corine categories (nagy et al., 2019). soil data exact determination of subsurface conditions (water content of unsaturated and saturated soils) is crucial in our model building scenario, since both rakonczai et al. (2011) and farsang (2014) indicated significant interrelationship between the soil and the water balance of the site. the current model is based on the 250 m resolution 3d soil hydraulic database of europe (tóth et al., 2017). since there is no reliable data source available deeper than 2 meters for the study site (nor even hungary), the current research is based on the 2 m depth soil layer of the database. the author has updated the following parameters of the original model: saturated water content, saturated hydraulic conductivity, and moisture retention curve. the parameters of deeper geological layers were spatially estimated based on 13 borehole records provided by ativzig. topography since topographical conditions determine overland and underground flows significantly, an accurate digital elevation model is crucial for a successful modelling scenario. the present study is based on a 10 x 10 m resolution dem. to run the mike she model, it is necessary to convert the dem data into a spatial distribution grid point file (.dfs2). point file was created using arcgis and could be converted to a .dfs2 file using the mike zero toolbox (dhi, 2017). the resulted spatial distribution grid can be used as input data. water flows surface channels provide unobstructed gravitational flow paths for the water into its recipient reservoir, thus proper knowledge of the geometry of the channels and surface depressions can significantly improve the model reliability. in the current framework, the water network geometry is provided by ativizig, and it can be classified into two main groups. the first class includes tran 2021 / journal of environmental geography 14 (3–4), 1–13. 5 brooks from the previous epoch, whereby paths are provided, cross-sectional data are measured, and data is set up as 3d gis points. other types of brooks are managed by ativizig. in this case the pathlines are provided as a polyline shapefile, the cross-section data is defined by longitudinal profile and different cross-section data. these data are set up in the specialized mike hydro hydraulic module. the module enables complex dynamic river network modelling and can be linked to mike she to comprehensively simulate hydrologic modelling of the catchment under investigation. groundwater data groundwater has more stable water level and is less affected by external factors than the unsaturated zone or the channels. the groundwater series provided by ativizig includes 33 groundwater measurement stations with specific coordinates from 2010 to 2018. the groundwater level changes according to topography and all flows into the tisza river and seasonal variation greatly affects groundwater change. based on the measured data in the period 2010-2018, the highest groundwater level in the study area usually occurs in april-may, the lowest in october-december. however, there are different rainfall and temperature conditions at some measurement points, so the difference is up to 2-3 months of the year. computational layers to simulate the flow processes occurring in the saturated zone it is necessary to define computational layers. in the mike she model the numerical vertical discretization is defined by explicitly defining the lower level of each calculation layer. the spatial distribution of lower level is uniform, the value of aquifer lower level is -75 m. to make corrections to the elevations layers, the minimum layer thickness is applied with a value of 2 m, this is to prevent zero-thickness or very thin layers. to define outer boundary conditions this model applies a fixed head type, based on a spatially distributed and time-varying dfs2 file, extracted from the specified groundwater table. specified groundwater table is established based on daily groundwater elevation data from 2010 to 2018. specified groundwater table is divided into 200 m x 200 m grid cells. mike she then interpolates in both time and space from the .dfs2 file to the local head boundary at each local time step (dhi, 2017). calibration data the mike she model built for dong-ér catchment lacks a lot of data such as brook water-level and discharges to be fully calibrated and validated. the current model has only been calibrated focused on groundwater data for 2018-years' springtime by nagy et al. (2019). comparing simulation results and measured data, the variance is about 45 cm, which is very suitable considering the lack of input parameters and uncertainties (such as topographic maps, vegetation features and soil characteristics). there are many parameters that need calibration to make the model more complete, for example a saturated hydraulic conductivity for unsaturated flow calibration and hydraulic conductivity, specific yield, specific storage for groundwater flow calibration. however, due to the lack of data and not the objective of the study, it was not mentioned. mike she output results the output results obtained from the mike she simulation depend on the selected modelling sequence. according to the mike she user guide (2017), the model saves the results in three groups of files, these are 1) ascii files, which is a catalogue of all output files (.sheres) of the simulation; 2) a binary output file containing all the static information of the simulation (.frf); 3) the simpler, timeseries-generated dfs0, 2dimensionally defined dfs2, and 3-dimensional dfs3 files (.dfs). in this study only the results in .sheres format and the time series results (dfs0, dfs2, and dfs3) for the water balance are examined (table 2). the water balance simulation can be performed with a separate module, water balance calculation, which delivers results of a post-processing of the data stored in the .sheres file. the common understanding which states that all water flows into system are positive and all outflows or loss of water is negative. the storages of water system are positive in case of storage increase. positive water balance change means that the change in storage plus the total outflows is less than the total inflows (δstorage + outflow < inflow). among several hydrological parameters and water balance components, the following were examined in table 1-2. modelling in the first stage of the sensitivity analysis, the input data can be divided into two groups, according to their temporal variability. the first type is constant in long timespan, including the topography, water networks (rivers and lakes), soil properties, geological features. this phenomenon has negligible changes or remains unchanged in the long run without human activities. the other group consists of data that change rapidly, whether minute by minute, hour/day, or seasonally. such features are daily precipitation, daily mean temperature, reference evapotranspiration, and land cover (including vegetation). thereafter the one at a time type sensitivity analysis was elaborated by five mike she simulation scenarios, including base simulation (bs), sim1, sim2, sim3 and sim4 simulations (fig. 2). base simulation (bs) is used to simulate integrated hydrological processes and water balance in dong-ér catchment in 2018. the following factors supported the reason 2018 was chosen to run the base model: 1) the model has been calibrated by nagy et al. (2019) according to the groundwater level measured in 2018. 2) the land cover data of the year 2018 used from corine land cover. 3) the latest van genuchten parameters of the moisture retention and hydraulic conductivity have just been updated by the author from the 3d soil hydraulic database in the previous year (tóth et al., 2017). 4) the precipitation measured in 2018 6 tran 2021 / journal of environmental geography 14 (3–4), 1–13. is much closer to the multi-annual average compared to the other years under investigation. thereafter the base simulation running for 2018 has been considered suitable to perform one-at-a-time sensitivity analysis and the outcomes were used as reference values to compare with the other simulation scenarios. the precipitation sensitivity analysis focused on the years with extreme precipitation (drought, rainy) and the table 1 output hydrological parameters used for research (source: dhi, 2017) parameters units notes actual evapotranspiration (actualet) mm/d actual evapotranspiration is depending on water availability at root depth and leaf area index (lai) actual transpiration (tact) mm/d evaporation of water is mostly through the pores of the leaves. actual soil evaporation mm/d actual soil evaporation is depending on factors such as soil characteristics, land use, vegetation. depth of overland water m it is the amount of water at the surface. overland flow in xand y-direction m3/s flow on the horizontal and vertical axis infiltration to unsaturated zone (uz) mm/d just like overland flow in y-direction, the vertical downward flows will be positive. unsaturated zone (uz) deficit mm unsaturated zone deficit is the amount of air in the unsaturated zone. thus, a decreasing deficit means that the more air has been pushed out by the water, the soil gradually becomes wetter. average water content in the root zone it is depending on precipitation, soil features, groundwater flow and vegetation features. water content in unsaturated zone (uz) contrast to unsaturated zone (uz) deficit groundwater flow in xand ydirection m3/s groundwater flow is in the horizontal and vertical axis. table 2 output water balance components used for research (source: dhi, 2017) name of components and in parentheses are abbreviations units precipitation mm evapotranspiration evapotranspiration (evapotrans), infiltration includes evapotranspiration (infilt.incl.et). exfiltration includes evapotranspiration (exfilt.incl.et) mm flows overland boundary outflow (ol bou.outflow). overland boundary inflow (ol bou.inflow). overland flow to river (ol->river/mouse). subsurface boundary inflow (subsurf.bou.inflow). subsurface boundary outflow (subsurf.bou.outflow). baseflow to river. baseflow from river mm storages canopy storage change (canopystor.change). snow storage change (snowstor.change). overland storage change (ol stor.change). subsurface storage change (subsurfstor.change) includes both unsaturated (uz stor.change)and saturated zone storage changes (sz stor.change), mm water balance change mm tran 2021 / journal of environmental geography 14 (3–4), 1–13. 7 year with average precipitation. in this part of the research, the precipitation data of the (bs) model was replaced by the drought season 2000 (sim1), rainy season 2014 (sim2), while keeping the other parameters of 2018 fixed. thereafter the differences of the three models have been compared to each other. the temperature sensitivity analysis focused on the effect of temperature increases on changes in results of hydrological parameters and water balance components. based on the results of the ipcc (2018) and omsz (2018b) climate models, the temperature data of 2018 (bs) reference model was increased by +1.5˚c (sim3) and +2.2˚c (sim4), while the other parameters left unchanged. thereafter the differences of the three models have been evaluated. results due to time and hardware constraints, hydrological results were only extracted from cells near the settlement of tiszaalpár, rather than from whole catchments. the area near the settlement of tiszaalpár has a low elevation, so it is more susceptible to groundwater level rises by extreme precipitation events or flood wave of tisza. however, the simulation results in figure 3 show the opposite, specifically on september 13, 2014, with 49.8 mm of precipitation, but the depth of overland water component gave a low value from 0.74 mm-0.77 mm, so there is no significant change for heavy rain events. there is a direct correlation between the precipitation events and infiltration because the top surface soil has a high permeability, most of the precipitation when reaching the surface is mostly absorbed into the soil. the amount of infiltration into the soil is 20.6 mm, the unsaturated zone deficit is 14.8 mm. the water leaving the system through evapotranspiration, whose rate is from 1.1 mm/day to 4.1 mm/day on the 13 september of analysis years. however, the water content (~16.5 mm) infiltrates to unsaturated zone does not appear yet in the unsaturated zone (water content in unsaturated zone is 0.5 mm) and in the root zone (0.4 mm). this can be explained as a quantity of infiltrated water which is clinging to the dry soil particles, thus temporarily stored in the upper soil layer and infiltrates very slowly to the unsaturated zone because the leakage coefficient of sand is very small, about 10-5 m/s. thus, it can be affirmed that even in years with high precipitation conditions like 2014, the rainfall shows no significant correlation with surface water and groundwater. among the hydrological parameters related to the precipitation events, the unsaturated zone deficit and infiltration are found to be the most sensitive. to explore the relationship and correlation between water balance components for the entire catchment can be performed with a water balance calculation module of the mike modelling environment (figs. 4-5). based on the values of the accumulated water balance components in the whole test years, it can be concluded that the components of subsurface boundary inflow, overland boundary outflow, evapotranspiration and precipitation have a high impact on the entire catchment water balance. the precipitation will supplement the overland storage change (12 mm and 19 mm) in some deflationary depressions and low permeable topsoil, the overland flow (-5 mm and -10 mm) direct addition to brooks (fig. 4). however, these amounts are not much compared to the amount of precipitation and of overland boundary outflow. fig. 2 research workflow 8 tran 2021 / journal of environmental geography 14 (3–4), 1–13. according to the results shown in figure 5 can see that as precipitation increases, the infiltration also increases from 32 mm in 2000 to 138 mm in 2014 (increased rate is 331%). in all three years, the amount of water lost through evapotranspiration was more than precipitation, with the rate of 154% more in 2000, 7.7% more in 2014 and 35% more in 2018. the year 2000 has the largest difference rate, this further aggravates the dehydration of the topsoil. thus, it can be confirmed that evapotranspiration includes direct evaporation and indirect transpiration through vegetation which has caused a large amount of water loss from surfaceand groundwater. the change in unsaturated water storage (from 2000 to 2014 increased by 166 mm) is much larger than that in saturated (increased by 35 mm), which again shows that most of the water infiltration into the soil is stored in the topsoil layer. overland boundary outflow values were higher for precipitation and evapotranspiration in all three study years. based on these results, the above statement is confirmed that the source of overland flow in the dong-ér catchment is not primarily the precipitation or the overland boundary inflow. the question is where does overland boundary outflow (surface water of brooks) get its water? the watercourse nature of dong-ér can rather be observed close to the inner area of kiskunhalas. from this point, the water supply of the brook is gained from three sources. first, the subsurface boundary inflow source from high elevation fig. 3 temporal changes simulated up to 13 september as a result of precipitation events in the reference year 2018, drought events of 2000 and the rainy year of 2014 fig. 4 water balance values accumulated from the beginning to the end of the study years tran 2021 / journal of environmental geography 14 (3–4), 1–13. 9 areas flows to the surface water in the lower area under the influence of gravity. figure 6 shows the elevation of the groundwater level measurement stations and the elevation of the terrain. according to figure 6 and to the principle of communicating vessels, subsurface boundary inflow will continuously supply the surface waters from the nw, sw and w directions. on this basis, it can be concluded that the surface and groundwater dividing lines are unlikely to fall into one. in the process of water moving underground, an amount of water from 10 mm and 211 mm is stored at the subsurface storage and shows an increasing trend for fig. 5 water balances for the 2000 drought and 2014 rainy years (modified after dhi, 2017) fig. 6 the elevation of the groundwater measurement stations and the elevation of the terrain 10 tran 2021 / journal of environmental geography 14 (3–4), 1–13. rainy events. in high elevation areas, the height difference between the ground water level and the topography is not large, even considering the brooks bottom elevation, it is often lower than the groundwater level, so in the area near the settlements of kecskemét, kiskunhalas and bócsa groundwater continuously replenishes the brooks and the deflation hollows. in low elevation areas such as baks and tiszaalpár settlements, where the groundwater level is also close to the terrain level, in the rainy season, when the groundwater level rises, the phenomenon of upwelling excess water inundation occurs and so on continuously adding water to the brooks. only an amount of -96 mm to -105 mm of subsurface boundary outflow exits the catchment system to join the tisza river flow (fig. 5). subsurface water flowing from the outside into the dong-ér catchment provides ~90% of the water for the brooks (overland outflows). it can be confirmed that for the entire water balance of the catchment, there is a close relationship between the subsurface inflows and overland outflow (surface water of brooks) components. in addition to the subsurface water inflow from the outside, the amount of rainwater that falls directly and infiltrates to replenish water into the brooks, and the source of wastewater from settlements, but according to actual observations, this amount is not significant. a comparison of the water balance results of extreme precipitation events (2000 and 2014) shows that the sensitivity is in descending order of the following components: infiltration include evapotranspiration (331.3%), overland flow to river (100%), subsurface storage change (-95.3%), evapotranspiration (75.4%) and overland storage change (58.3%) (fig. 5). water balance change from drought and rainy years are -497 mm and 84 mm, so in a rainy year the system can store 413 mm more, which is 877 million m3 of water. negative value of water balance change shows that the amount of loss is more than the amount that is in and flows into the system. thus, the conclusion is that even in the year with a lot of precipitation, the water balance of dong-ér catchment is still lacking water. the next section is to analyse the sensitivity of the hydrological parameters shown in figure 7 under the influence of temperature increase +1.5˚c and +2.2˚c. the actual evapotranspiration increased by 41% under the influence of +1.5˚c and increased by 67% when the daily temperature increased by +2.2˚c. the unsaturated zone deficit parameter also showed high sensitivity, namely an increase of 37% and 57%, respectively. a temperature increases of +1.5˚c causes actual transpiration to increase by 6% compared to soil evaporation. the largest inverse fig. 7 change in hydrological parameters due to temperature changes of +1.5 °c and +2.2 ° compared to the reference value on august 10, 2018 (y = 0 horizontal axis) fig. 8 water balance values accumulated in the whole of 2018 due to temperature changes of +1.5 ˚c and +2.2 ˚c compared to the reference values (y = 0 horizontal axis) tran 2021 / journal of environmental geography 14 (3–4), 1–13. 11 proportionality change is the overland flow in x-direction parameter, even with a decrease of 21% for + 1.5˚c and 28% for a temperature rise of + 2.2˚c (fig. 8). so, these hydrological parameters are the most sensitive to temperature rise. among the parameters in figure 8, unsaturated deficit, actual evapotranspiration and infiltration to unsaturated emerged as the main factors, with higher values than other parameters. temperature rise has the greatest effect on the value of the unsaturated deficit. in addition, increasing temperatures also increase actual evapotranspiration and naturally decrease the infiltration. the rest of the parameters have intraday values less than 1.0 mm. meanwhile, the amount of precipitation on august 10, 2018 is zero. this again shows that the amount of water present and operating on this day is derived from the water that has been stored in the top layer from previous periods. precipitation that reaches the ground surface, mostly infiltration into the deeper layers of the soil with delay and the rest will flow on the surface in the x direction (in the slope direction). based on the results in table 3, the subsurface boundary inflow, overland boundary outflow and evapotranspiration components have a high weight on the studied water balance. the water balance of the dong-ér catchment is highly dependent on the influence of subsurface boundary inflow from the external area. evapotranspiration increases with increasing temperature greatly reduced subsurface (uz and sz) storage (from 48.5% to -66.5%). overland storage change is reduced from -14% to -21%, so the baseflow to brooks and the sources to surface water are also reduced. increasing temperature does not change the baseflow from minimum depths of brooks, where the water is always present, so the value does not change compared to 2018 (all equal to 4 mm). the conclusion is that increasing temperatures reduce the water retention of the brooks, especially in areas where its terrain level is higher than the groundwater level. the overland boundary inflow in all three temperature conditions is zero, thus the surface watershed boundary has been correctly defined. canopy and snow storage change in all three temperature conditions are zero, this is because the values are all very small, less than 0.03 mm so when rounding the number is zero. the subsurface boundary inflow source is very stable and plays an important role in the water balance of the dong-ér catchment. subsurface boundary outflow parameters tend to decrease from -4% to -6%, partly due to additional seepage migration for groundwater and the rest being evaporated by vegetation. when considering the values of two parameters infiltrationand exfiltration including et, it can be concluded that meanwhile temperature increases, infiltration decreases more strongly (-41% and -61%), while exfiltration decreases less. the water balance change of 2018 show values around -357 mm, which practically more than table 3 change in accumulated water balance in the whole of 2018 due to temperature changes of + 1.5 °c and + 2.2 °c and the differences compared to the reference value (diff1 and diff2) parameter reference (+)1.5 ˚c (+)2.2 ˚c change (%) change (%) precipitation (+)589 (+)589 (+)589 0 % evapotranspiration (-)795 (-)889 (-)924 12 16 ol boundary inflow 0 0 0 0 0 ol boundary outflow (-)1042 (-)1036 (-)1032 -1 -1 canopy storage change 0 0 0 0 0 snow storage change 0 0 0 0 0 ol≥brooks (-)9 (-)7 (-)6 -22 -33 ol storage change 14 12 11 -14 -21 uz storage change -98 -153 -168 -56 -71 sz storage change -39 -55 -63 -41 -62 baseflow to brooks (-)12 (-)11 (-)10 -8 -17 baseflow from brooks (+)4 (+)4 (+)4 0 0 subsurface boundary inflow (+)1132 (+)1137 (+)1140 0 1 subsurface boundary outflow (-)101 (-)97 (-)95 -4 -6 infiltration include et (+)109 (+)64 (+)43 -41 -61 exfiltration include et (-)1170 (-)1154 (-)1147 -1 -2 water balance change (-)357 (-)506 (-)554 42 55 note: the sign in parentheses indicates the direction of the water flow. not in parentheses is the value 12 tran 2021 / journal of environmental geography 14 (3–4), 1–13. 758 million m3 of water is leaving the water system. the increase in temperature of +1.5˚c and +2.2˚c reduces the water balance of the dong-ér catchment by 42% and 55%, i.e., more than 316 million m3 and 418 million m3 less water than in 2018. increased temperatures directly and indirectly increase the amount of water lost through evapotranspiration and thus the water balance of the basin is significantly reduced. based on these results, it can be concluded that subsurface storage change, infiltration include evapotranspiration, water balance change, overland flow into the brooks, overland storage components change to a greater extent than evapotranspiration changes, i.e., greater than 12% and 16%, so these parameters are sensitive to the increasing temperature of climate change. conclusion the unsaturated zone deficit, infiltration to unsaturated zone, evapotranspiration and overland flows parameters seems to have a great weight in the daily hydrological circulation and have a highly sensitive to climate change conditions. the precipitation rapidly seeps the soil and temporarily stored in the upper soil layer and infiltrates into the deeper layers of the soil with delay and the rest will flow on the surface in the x direction (in the slope direction). during this time a large amount of water will leave the system through evapotranspiration. based on the relationship between manifestations of climate change and water balance components, probably the subsurface boundary inflow and evapotranspiration are the two main driving forces that constitute and regulate the water balance of the dongér catchment. according to the models, the water balance in dong-ér catchment is significantly determined by the subsurface boundary inflow since it continuously supplies about ~90% of the surface water. subsurface boundary inflow does not show a close relationship with temperature change or extreme precipitation events. meanwhile, evapotranspiration is highly dependent on the temperature. due to the warming trend, the water retention of the dong-ér brook showed a decreasing trend, especially in areas where the groundwater level is deeper than the bed level of the brook. the components that play an important role in the water balance of the dong-ér catchment in descending order are as follows: subsurface boundary inflow, overland boundary outflow, evapotranspiration and precipitation. however, among the components, subsurface storage change, infiltration include evapotranspiration, overland flow to brook, overland storage change and evapotranspiration components are the most sensitive to climate change. based on the water balance change of the model, the temperature increases of + 1.5˚c and +2.2˚c causes to lose more water than during the drought period in the dong-ér catchment in 2000. even such rainy years like 2014, the multi-annual water deficit can’t be replenished from the system. ultimately, this causes the water balance of catchment to be in a state of water shortage. in the light of climate change, water shortage is probably getting worse in the dong-ér catchment. the results of the study have also shown the effectiveness of the mike she model and the water balance calculation module as useful tools to analyse and evaluate the effects of the changing climatic conditions on the hydrological parameters. however, the mike she model also has disadvantages such as mike she only calculating the permeability in the vertical direction, the calculation of the permeability value wrong in the area with high slope. besides, the need for a lot of data with good quality, the difficulty of monitoring data, and changing environmental conditions in the future are issues that need to be improved, so the values of the calculated parameters cannot be absolutely accurate but gives an approximate value and trend. the results of this study can be a reference for managers, landowners and other stakeholders in the planning, management and effective use of water resources are in a state of decline in the context of increasingly complex climate change. acknowledgement i am grateful to dhi hungary ltd. for the mike she student license. thanks to the director of ativizig, dr. péter kozák and his colleagues for their professional advices and supports. i am grateful to professor emeritus 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acknowledgement references the impact of soil erosion on the spatial distribution of soil characteristics and potentially toxic element contents in a sloping vineyard in tállya, ne hungary journal of environmental geography 14 (1–2), 47–57. doi: 10.2478/jengeo-2021-0005 issn 2060-467x the impact of soil erosion on the spatial distribution of soil characteristics and potentially toxic element contents in a sloping vineyard in tállya, ne hungary samdandorj manaljav1,2, andrea farsang2, károly barta2, zalán tobak2, szabolcs juhász2, péter balling3, izabella babcsányi2* 1institute of geography-geoecology, mongolian academy of science,erkhuu str. 11th khoroolol, sukhbaatar district, ulaanbaatar, mongolia 2department of geoinformatics, physical and environmental geography, university of szeged, egyetem u. 2-6, 6722 szeged, hungary 3research institute for viticulture and oenology, tokaj, könyves kálmán u. 54., tarcal, hungary, hu-3915 *corresponding author, email: babcsani@geo.u-szeged.hu research article, received 25 february 2021, accepted 23 april 2021 abstract soil erosion is a main problem in sloping vineyards, which can dramatically affect soil quality and fertility. the present study aimed to evaluate the spatial patterns of selected physico-chemical soil characteristics and the soil's potentially toxic element (pte) contents in the context of erosion. the study was conducted in a 0.4 ha vineyard plot on a steep slope in tállya, part of the wine-growing region of tokaj-hegyalja (hungary). a total of 20 topsoil samples (0-10 cm) were collected and analysed for ptes (b, co, ba, sr, mn, ni, cr, pb, zn, and cu), soil ph (deionized water and kcl solution), particle-size distribution, soil organic matter (som), (nitrate+nitrite)n, p2o5, and carbonate content. among the selected ptes, only cu (125±27 mg/kg) exceeds the hungarian standards set for soils and sediments (75 mg/kg) due to the long-term use of cu-based pesticides in the vineyard. examined ptes are negatively correlated with the sand content of the topsoil, except for mn, while the significant positive relationship with the clay content shows the role of clay in retaining ptes in soil. som seems to play a minor role in binding ptes, as cu is the only element for which a significant correlation with the som content can be detected. the spatial distribution maps prepared by inverse distance weighting (idw) and lognormal kriging (lk) methods show higher pte contents at the summit and the shoulder of the hillslope and lower contents at the backslope and the footslope zones. the low slope gradients (0-5 degree) and the high contents of the coarse fraction (> 35%) likely protect the soil at the summit and the hillslope’s shoulder from excessive erosion-induced losses. while the reraising pte contents at the toeslope are likely due to the deposition of fine soil particles (silt and clay). the highest som contents at the summit and the toeslope areas, and increased contents of the coarse fraction at the backslope, confirm the effects of soil erosion on the spatial distribution patterns of main soil quality indicators. overall, the lk outperformed the idw method in predicting the soil parameters in unsampled areas. keywords: ptes, soil organic matter, soil erosion, tokaj, geostatistics, interpolation introduction viticulture is known to affect soil quality significantly, both its physical and chemical properties. soil is one of the most important factors in viticulture, because its physico-chemical properties (e.g. ph, particle-size distribution, soil organic matter and n-, pmacronutrient contents) determine the nutrient supply for the growth of the vine. in general, vineyard soils tend to be poor in macronutrients and organic matter contents, and a general decrease in soil ph is often observed in older vineyards (patinha et al., 2018). past and present soil management in a vineyard, especially tillage in the vine inter-rows, is responsible for the degradation of the soil's physical characteristics that may have dramatic effects on its nutritional element contents (biddoccu et al., 2016). surface and subsoil hydraulic conductivity is highly affected by different soil management practices in vineyards (bordoni et al., 2019). for example, tractor traffic has a considerable impact on the spatial distribution of the soil's water infiltration capacity and compaction, resulting in more surface runoff generation and enhanced soil erosion (biddoccu et al., 2016; capello et al., 2019). the rock fragment content and its spatial variability are also influenced by soil erosion and cultivation patterns in vineyard topsoils (follain et al., 2012). besides these fundamental characteristics of the soil, some specific soil components are also affected by viticultural practices and soil erosion dynamics. contamination of agricultural soils with potentially toxic elements (ptes) may raise human health concerns due to their ability to integrate the human food chain. ptes often show increased concentrations in agricultural soils due to the long-term use of chemical fertilizers and pesticides (solgi et al., 2016). biosolid applications may also increase pte contents in agricultural soils, including pb, ni, zn, cu, cd, cr, and even contents of some rarely assessed ptes, such as ba (ippolito and barbarick, 2006, mailto:babcsani@geo.u-szeged.hu 48 manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. torri and corrêa, 2012). however, pte accumulation in the topsoil of biosolid-amended arable lands is not always detectable (ladányi et al., 2020). elevated contents of cd, cu and zn have been observed in chinese agricultural soils due to repeated treatments with chemical fertilizers and manure (lu et al., 2012; sun et al., 2013), additionally, pb also accumulated in agricultural soils of the european mediterranean region (micó et al., 2006). in vineyard soils, cu and zn are often observed at elevated concentrations due to the repeated use of cuand znbased agrochemicals (rodríguez martín et al., 2006, dos santos et al., 2013). in europe, cu-based fungicides have been intensively used since the end of the 19th century to control fungal diseases. high cu contents can accumulate in the topsoil of vineyards and surrounding areas, which may raise ecotoxicological concerns (milićević et al., 2017, ungureanu et al., 2017, patinha et al., 2018). additionally, the foliar applications of micronutrient fertilizers containing fe, mn, b, cu, zn and mo are part of viticultural practices. therefore, pte concentrations in conventionally managed vineyard soils should be carefully assessed and the eventual pte accumulation in the topsoil evidenced. on the other hand, soil erosion influenced by various agronomic practices can also considerably impact the spatial patterns of pte soil contents. vineyards are often planted on steep slopes, thus they are prone to intensive soil erosion, enhancing the mobility of ptes (rodríguez martín et al., 2007, dos santos et al., 2013). according to model forecasts, fewer but more intense rainfall events are likely to occur in hungary during the 21st century (mezősi and bata, 2016). as rainfall intensity is a key triggering factor of soil erosion, its probable increase in the future can have dramatic effects on soil erosion rates, which will certainly impact soil quality. the spatial variability of topsoil ptes may be affected by soil erosion processes and anthropogenic inputs. given that some ptes are also essential micronutrients for plants, their soil contents are an indicator of soil fertility too. also, key soil properties, such as soil organic matter content, particle size distribution, and soil ph, are required to explain the distribution of ptes. overall, there is an increasing need to understand the impact of soil erosion on the spatial distribution of essential physico-chemical properties and pte contents in cultivated soils (rodríguez martín et al., 2006; solgi et al., 2016). predictive soil mapping has been efficient for assessing the spatial variability of soil properties at the field scale (scull et al., 2003). however, few studies focused on mapping and explaining the spatial distribution of soil characteristics and ptes in vineyards at a plot scale. yet, this information is necessary to monitor soil quality changes as a consequence of soil erosion. the key objectives of this study are: (i) to identify relationships between soil properties and pte contents, (ii) to map the spatial distribution of essential soil characteristics and specific pte contents in a vineyard's topsoil; and (iii) to assess the accuracy of the applied interpolation models. methods and materials study area and soil sampling the field survey was carried out in a 0.4 ha vineyard plot at the foothills of the tokaj mountains (north-eastern hungary), in tállya, part of the historical wine-growing region of tokaj-hegyalja (fig. 1). the vineyard's elevation ranges from 269 m to 291 m above sea level. the plot has nine grapevine rows parallel to the main slope; vine stocks are spaced 1 m from one another, while fig. 1 a) the study area is a 0.4 ha vineyard plot near tállya in the tokaj wine region (ne hungary). the slope profile (b) and slope map (c) were prepared based on the digital elevation model of the area. sampling points are marked in blue for the training samples and red for the validation samples. manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. 49 the inter-rows are 3.8 m wide. the total slope length is 130 m, and the mean slope is 18°. the soil type slightly varies along the transect. at the top of the hillslope, it belongs to the skeletic regosol (loamic, ochric) type, while at the backslope it shows skeletic leptosol (loamic, ochric) patterns, at the footslope the soil is skeletic colluvic regosol (loamic, ochric) according to the world reference base for soil resources (2014). the soils in the area developed on a fine-grained extrusive igneous rock, rhyolite, and rhyolite tuff. therefore, the soil has a weakly acidic character. the vineyard is managed conventionally with regular uses of synthetic and inorganic pesticides, primarily cu fungicides. the current application doses of the bordeaux mixture amount to 2-2.5 kg/ha/year (applied three times a year in may, june, and july). the bordeaux mixture was complemented with a foliar micronutrient fertilizer pulverized in a dose of 4-5 l/ha, containing fe (3.2 m/v%), mn (0.32 m/v%), cu (0.15 m/v%), b (0.31 m/v%) and mo (0.003 m/v%). the soil is regularly ploughed, and no cover crops are sown in the vine interrows for soil protection. in may 2020, 14 point samples of topsoil (0-10 cm) were taken in the middle of the vine inter-rows based on random sampling (usda, 2014) (fig. 1). additionally, six topsoil samples were collected in november 2019, which were used to check the interpolation methods' performance. aerial photography campaign using a dji phantom 4 drone and geodetic field measurements were performed to collect true colour images and elevation information. the digital elevation model (dem) of the vineyard plot was prepared by stereo-photogrammetry described elsewhere (szatmári et al., 2011). the slope map of the study area was generated from the dem as its first derivative. soil analyses all soil samples were air-dried at room temperature and passed through a 2 mm stainless steel sieve. the nonnegligible coarse fraction (>2 mm) was systematically weighed. soil organic matter was determined by oxidation with k2cr2o7 in the presence of sulphuric acid and the subsequent analysis of the reduced cr3+ ions with a spectrophotometer (unicam helios gamma uv-vis, thermo scientific) according to the walkley black method based hungarian standards (msz 21470– 52:1983). the carbonate content was measured by the volumetric method with a scheibler calcimeter. soil ph was determined by a ph-meter (mettler toledo fiveeasy) in a 1:2.5 ratio of soil: deionized water (phd.w.) and soil: 1 mol/l kcl (phkcl) (msz-08-0206-2:1978). differences greater than one between the two ph values measured in the deionized water and the kcl solution suggest a susceptibility of the soil to acidification (rodrigo comino et al., 2016). the pipette method was used to determine soil particle size distribution using pyrophosphate for dispersing soil aggregates (usda, 2014). the plant-available macronutrient contents of p2o5 extracted using ammonium-lactate and (nitrate+nitrite)-n extracted with a kcl-solution according to standard procedures (msz20135:1999), were measured by a flow injection analysis (fia) spectrometer (fia star 5000, foss). pseudototal pte analyses digestion in aqua-regia allows for determining the socalled pseudototal element content because it does not dissolve the silicate matrix. soil samples (<2 mm) were ground to a fine powder (<0.25 mm) in an agate ball mill and dried in an oven at 105°c for 24 h. approximately 0.5 g of each ground soil sample was weighed into precleaned pfa vessels using an analytical balance and digested in aqua regia (hcl: hno3 ratio of 3:1). all labware was acid-cleaned before use, and acids were for trace metal analysis (normatom®, vwr chemicals). the pseudototal digestion was performed in a laboratory microwave digestion system (multiwave 3000, anton paar). after cooling, the digested samples were filtered into 50 ml volumetric flasks (acid-cleaned plastic flasks), and the volume was made up with ultrapure water (tka micropure). the concentrations of selected ptes (b, co, ba, sr, mn, ni, cr, pb, zn, and cu) were then determined by an inductively coupled plasma optical emission spectrometer using yttrium as an internal standard (optima 7000 dv, perkin elmer) (±5%). calibration standards were freshly prepared in 2% hno3 by diluting icp multi-element standards (cpachem). erm®cc141 certified reference material (a loam soil) was used for quality control for the pseudototal element analysis. the recoveries for the certified elements (based on two digested aliquots of the reference material and four icp analyses) are presented in table 1. data analyses descriptive statistical analyses (minimum, maximum, mean, median, standard deviation, skewness, and kurtosis) were used to describe the soil characteristics and ptes. the coefficient of skewness is a measure of the symmetry of a distribution. for symmetric distributions, the coefficient of skewness should be close to zero and the kurtosis must be near 3. the mean is greater than the median for positively skewed distribution and vice versa for negatively skewed distribution. pearson's correlation was used to define the relationships between soil characteristics and pte contents. all statistical analyses were carried out using ibm spss statistics 25. table 1 the recoveries of the pseudototal element (aqua regia extractable) contents in erm®-cc141 certified reference material (n=4) and the pte contents of the local forest topsoil used as a reference for calculating enrichment factors in the vineyard soil. unit b* mn ni cr cu pb zn co ba* sr* recovery % 102±2 117±2 116±2 104±3 87±1 92±2 88±0.2 local forest soil mg/kg 2 424 8 11 7 27 35 2 48 9 *the erm®-cc141 is not certified for b, ba and sr. 50 manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. enrichment factors (efs) were calculated to compare pte contents observed in the vineyard topsoil with pte background levels measured in a local forest topsoil (average of pseudototal pte contents measured in 0-10 cm and 10-20 cm) (table 1). 𝐸𝐹 = pte(vineyard topsoil) pte(reference soil) (1) the observed pte contents were also compared with the median pte concentration data collected in the framework of the hungarian soil information and monitoring system (sims) based on 842 topsoil sampling points (0-30 cm) on arable land nation-wide in hungary (csorba et al., 2014). geostatistical approaches in geostatistics, variograms or semivariograms are applied to measure the spatial patterns of a known variable. its main contribution in soil science has been predicting and mapping the spatial variability of soil attributes at unsampled locations (goovaerts, 1999; guo et al., 2001). interpolation is a process of estimating the values at unsampled places based on known values at sampled locations. in this study, interpolation maps were created using arcgis 10.5 geostatistical analyst extension (esri, redlands, ca). we set the nearest 2 to 8 neighbour values and a sector type of 4 for defining neighbourhood to interpolate a surface. the estimated standard errors of kriged values can be used to test the accuracy of the kriging results (rodríguez martín et al., 2006). several geostatistical methods exist for modeling the spatial variability of data (szatmári et al., 2015). however, ordinary kriging is a robust and one of the commonly used spatial interpolation methods to estimate the value of target variables at unsampled points using the weighted average of sampled neighbouring points in the area of interest. ordinary kriging computes a weighted average of the data: �̂�(𝑿0) = ∑ 𝜆𝑖 (𝑿0)𝑍(𝑿𝑖 ) 𝑛 𝑖=1 (2) where, �̂�(𝑿0) is the estimated value of the variable z at any location 𝐱0; 𝑍(𝑿𝑖 ) is the measured data; 𝜆𝑖 (𝑿0) refers to the weight associated with the measured values, and n is the number of observations in a neighborhood. lognormal kriging (lk) is the ordinary kriging of the measured values' logarithms (webster and oliver, 2007). it is used for strongly positively skewed data that approximate a lognormal distribution, commonly the case with environmental data. for lognormal kriging the data should be transformed by the following equation: 𝑦 = 𝑙𝑜𝑔10𝑍 (3) inverse distance weighting (idw) is more popular and based on inverse functions of distance in which the weights are defined by: 𝜆𝑖 = 1/|𝑥𝑖 − 𝑥0| 𝛽 𝛽 > 0 (4) data points near to the target point carry larger weights than those further away. the most popular choice of β is 2 so that the data are inversely weighted as the square of the distance. its attractive feature is that the relative weights decrease rapidly as the distance increases, and so the interpolation is locally sensible. furthermore, because the weights never become zero, there are no discontinuities. its disadvantages are that the weighting function's choice is arbitrary, and there is no measure of error (webster and oliver, 2007). assessment of model performance in this study, independent validation was used to evaluate and compare the performance of interpolation models. the root mean square error (rmse) measures the difference between predicted values and observed values, while the mean absolute error (mae) computes how far estimated values are away from measured values (xie et al., 2011). the smaller mae and rmse values indicate the better-predicted values. the rmse and the mae were estimated using the predicted and observed values at each validation sampling location: 𝑅𝑀𝑆𝐸 = √ 1 𝑛 ∑(𝑃𝑖 − 𝑂𝑖 ) 2 𝑛 𝑖=1 (5) 𝑀𝐴𝐸 = 1 𝑛 ∑ ǀ𝑃𝑖 − 𝑂𝑖 ǀ 𝑛 𝑖=1 (6) where 𝑃𝑖 , 𝑂𝑖 are predicted (interpolated) and observed soil parameter values at location 𝑖, and n is the sample number. results and discussion soil characteristics and pte concentrations in the vineyard topsoil the descriptive statistics of the examined soil characteristics and pte contents in the vineyard topsoil in tállya are summarised in table 2. most soil properties had positively skewed distributions except for caco3, p2o5, and clay content. but most of the ptes had negatively skewed distributions except for the concentration data of co and sr. the examined vineyard soil is slightly acidic (phd.w.(mean): 6.4). however, the soil has a potential acidity due to the greater than one difference between the two ph values (measured in d.w. and in the kcl solution). mean concentration of the soil organic matter (som) content is 1.5±0.4%, indicating that the vineyard soil is poor in som. a poor som content is often observed in vineyards planted on steep slopes as a consequence of intense soil erosion and redeposition and/or off-site export of organic carbon with surface runoff (novara et al., 2018). som can influence pte (particularly cationic metals) sorption in soils, probably attributed to its high cation exchange capacity (rodrigues et al., 2010). hence it is essential to assess som variations in the vineyard topsoil. the topsoil has a low carbonate manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. 51 content (caco3) ranging from 0.4 to 2.0%. the ammonium-lactate soluble p2o5 content ranges from 107.9 to 299.4 mg/kg, while the kclsoluble (nitrate+nitrite)-n content is low in the soil, varying from undetectable to 2.5 mg/kg. the vineyard soil in tállya is characterised by a high proportion of the coarse fraction (>2 mm): 31-48%. such important proportions of the coarse fraction embedded in the topsoil greatly impact soil erosion losses (gong et al., 2018). the soils belong to the clay loam, sandy clay loam, loam textural categories depending on the hillslope position. the mean sand (0.052 mm), silt (0.002-0.05 mm), and clay (<0.002 mm) fractions are respectively 41%, 27%, and 31%. the high standard deviations for mn (102 mg/kg), cu (27 mg/kg), and ba (25 mg/kg) indicate a marked heterogeneous spatial distribution in the topsoil of the vineyard plot. compared to the local forest topsoil we can observe increased pte concentration levels in the cultivated soil, except for mn and pb. the median efs range from 1.3 (for zn) to 17.9 (for cu) (table 3). the calculated efs (with the forest soil as a reference) indicate low enrichment for zn (1.3), co (2.4), ni (2.5), ba (2.1), and cr (2.3), more significant accumulation for b (3.8), sr (3.1) and a marked cu pollution of the vineyard soil (17.9). copper contents also exceed the hungarian environmental quality standards set for soils and sediments (joint decree no. 6/2009. (iv. 14) kvvmeüm-fvm). the efs calculated taking the hungarian arable soils as a reference show lower or no pte concentration increase in the vineyard soil. only b (ef: 1.6) and cu (ef: 8.5) are considerably enriched in the vineyard topsoil in tállya compared with the hungarian arable soils. altogether, these observations suggest that grape growing and more precisely, the related use of agrochemicals in vineyards significantly enriches the soil in ptes. only pb and mn contents are higher in the local forest topsoil underlining their geogenic origin. compared to arable soils, the elevated concentration levels of cu and b are attributed to plant protection practices specific to vineyards (and orchards). copperbased fungicides (such as the bordeaux mixture) are frequently applied to combat the fungal infections of grapevine, and micronutrient-rich fertilizers (with high b contents) are also regularly used in vineyards. boron accumulation in cultivated soils has rarely been evidenced so far. however, efs clearly demonstrate a moderate b accumulation in the vineyard soil due to current grape fertilizing methods. relationships between the soil pte contents and the soil characteristics the pearson's correlation coefficients (r) between soil properties and pte concentrations in the vineyard topsoil samples are summarised in table 4. according to correlation analysis, a strong positive relationship was table 2 descriptive statistics of selected soil parameters, macronutrient, and pte contents in the topsoil of the vineyard in tállya. vineyard topsoil (0-10 cm) unit min max mean median std.d skewness kurtosis som % 0.9 2.3 1.5 1.4 0.4 0.98 0.22 caco3 % 0.4 2.0 1.3 1.6 0.5 -0.96 -0.35 phd.w. 6.1 6.9 6.4 6.4 0.2 0.67 -0.48 phkcl 4.6 5.8 5.2 5.0 0.4 0.34 -1.65 (nitrate+nitrite)-n mg/kg <0.1 2.5 0.8 0.6 0.8 1.06 -0.07 p2o5 [mg/kg] mg/kg 107.9 299.4 196.6 200.1 55.7 0.02 -0.64 coarse fraction (> 2mm) % 31 48 40 40 5 -0.11 -0.82 sand (0.05 2 mm) % 32 60 41 39 9 0.93 0.00 silt (0.002 0.05 mm) % 21 35 27 26 4 0.42 0.04 clay (<0.002 mm) % 19 40 31 34 7 -0.53 -1.36 b mg/kg 6 13 10 10 2 -0.27 -1.32 mn mg/kg 199 607 351 355 102 0.84 2.19 ni mg/kg 10 23 17 19 4 -0.36 -1.19 cr mg/kg 14 35 25 26 7 -0.22 -1.49 cu mg/kg 88 184 125 127 27 0.44 0.25 pb mg/kg 10 17 14 14 2 -0.13 -0.98 zn mg/kg 32 64 44 45 8 0.68 1.53 co mg/kg 5 8 7 6 1 0.05 -1.84 ba mg/kg 63 136 101 102 25 -0.10 -1.65 sr mg/kg 19 42 30 28 7 0.34 -1.16 table 3 median enrichment factors (efs) of target ptes compared to the pte levels of a local forest topsoil and the hungarian soil information and monitoring system (sims) dataset. median pte contents of arable land (based on 842 sampling points) (csorba et al., 2014) are compared with the topsoil pte contents of the studied vineyard b mn ni cr cu pb zn co ba sr ef (local forest) 3.8 0.8 2.5 2.3 17.9 0.5 1.3 2.4 2.1 3.1 ef (sims) 1.6 0.9 1.0 8.5 0.8 0.8 0.7 52 manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. detected between the som content and the silt content (r = 0.84) of the samples, suggesting that particulate organic matter is mainly associated with the silt size fraction. similarly, parat et al. (2002) recovered the highest proportions of the soil organic carbon content in the silt fraction of burgundy vineyard loam soils. the ammonium-lactate soluble p2o5 concentration presented a positive relationship with som ( r = 0.52) and clay (r = 0.61) contents, implying that available p pools are present at higher concentrations in organic and clay-rich topsoil samples. on the contrary, a strong negative correlation was found between the clay and the sand (r = -0.91) contents indicating the size sorting effect of soil erosion that produces high sand and low clay and vice versa containing topsoils at distinct areas of the hillslope. correlation of the soil clay content with both ph values (measured in d.w. (r = -0.68) and the kcl solution (r = -0.79)) infer the role of exchangeable h+ and hydroxy-al ions adsorbed on clay minerals in determining soil (potential) acidity. significant correlation between som and silt contents with cu (r = 0.56 for som cu and r = 0.76 for silt cu) suggests that the silt-bound particulate organic matter and organo-mineral complexes govern cu binding in the vineyard soil. former studies performed in high-cu vineyard soils also emphasised the importance of the particulate organic matter in the sorption of pesticide-derived cu (besnard et al., 2001, parat et al., 2002, duplay et al., 2014). the closest relationship apparently exists between cu and ammonium-lactate soluble p2o5 contents (r =0.80). previous findings proposed that phosphate played a role in enhancing the adsorption of cu (and pb) to soil mineral phases, such as iron (hydr)oxides through the formation of ternary complexes (tiberg et al., 2013). soil ph and sand content showed negative correlation with the examined ptes (except for the pairs of ph and cu, sand and mn). the clay content that markedly affects the soil ph (as previously shown) is also anticorrelated to the sand content. this can explain the negative relationship between pte concentrations and sand content. indeed, the pte contents (except mn) are significantly and strongly correlated with the claysized fraction in the topsoil. clay-sized fractions are known carriers of ptes in soils owing to their important metal retaining capacities and specific (organo-)mineral composition (micó et al., 2006). therefore, clay minerals and clay mineral-organic matter complexes that primarily constitute the clay fractions (babcsányi et al., 2016) are proposed to be the main binding phases for b (r = 0.97), ni (r = 0.97), cr (r = 0.96), zn (r = 0.83), co (r = 0.71), ba (r = 0.93) and sr (r = 0.76) (significance at p< 0.01). a less significant correlation (significance at p< 0.05) in the case of cu (r = 0.62) and pb (r =0.60) with the claysized fraction presumes that additional soil constituents intervene in their binding in the soil, such as the silt bound som in the case of cu. in contrast, mn lacks any statistically significant relationship with the clay-sized fraction and soil characteristics involved in the study (except for ph d.w.). this dissimilarity of mn from the other target ptes table 4 pearson's correlation matrix between examined soil characteristics and ptes. the bold numbers denote statistically significant correlation coefficients (with p-value<0.05). som caco3 phd.w. phkcl (nitrate+ nitrite)-n p2o5 coarse f. sand silt clay som 1 caco3 -0.25 1 phd.w. -0.01 -0.14 1 phkcl 0.30 -0.15 0.89 ** 1 (nitrate+nitrite)-n -0.45 0.23 0.10 0.30 1 p2o5 0.52 0.26 -0.24 0.05 0.19 1 coarse franction -0.43 0.22 -0.44 -0.64* -0.22 -0.30 1 sand -0.31 -0.07 0.67** 0.65* 0.40 -0.45 -0.08 1 silt 0.84** -0.05 -0.28 -0.03 -0.30 0.61* -0.32 -0.60* 1 clay -0.06 0.11 -0.68** -0.79** -0.33 0.23 0.27 -0.91** 0.21 1 b mn ni cu cr pb zn co ba sr som 0.11 0.22 0.06 0.56* 0.05 0.14 0.14 0.17 0.07 0.31 caco3 0.2 0.40 0.17 0.09 0.21 0.34 0.10 0.39 0.27 0.32 phd.w. -0.71 ** -0.67** -0.76** -0.48 -0.78** -0.80** -0.59* -0.87** -0.82** -0.71** phkcl -0.74 ** -0.51 -0.78** -0.30 -0.78** -0.75** -0.51 -0.74** -0.79** -0.54* (nitrate+nitrite)-n -0.22 0.05 -0.25 -0.16 -0.23 -0.13 -0.13 -0.08 -0.18 -0.06 p2o5 0.41 0.37 0.36 0.80 ** 0.43 0.22 0.50 0.58* 0.45 0.74* coarse fraction 0.17 0.33 0.18 -0.13 0.22 0.46 -0.13 0.31 0.23 -0.00 sand -0.92** -0.46 -0.93** -0.83** -0.93** -0.63* -0.82** -0.79** -0.91** -0.88** silt 0.29 0.38 0.33 0.76** 0.33 0.34 0.32 0.47 0.37 0.61* clay 0.97** 0.36 0.97** 0.62* 0.96** 0.60* 0.83** 0.71** 0.93** 0.76** *correlation is significant at the 0.05 level (2-tailed). **correlation is significant at the 0.01 level (2-tailed). manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. 53 may stem from the predominantly natural (geogenic) origin of mn in the studied soil supported by the low (<1) ef (mn) compared to the local background (table 3.). this means that mn mainly enters the soil by weathering of the parent material rhyolite containing an average of 600 mg/kg mn according to gilkes and mckenzie (1988). moreover, mn's behaviour in soils is complex. mn is likely to exist in the form of precipitated manganic (oxy)hydroxides in soils with a reaction above ph 6.0, an insoluble form of mn (bradl, 2004). as shown in table 5, most of the analysed ptes are strongly correlated with each other. the mn, pb, and cu contents show weaker relations with the other selected ptes, which may be explained by diverse sources and/or geochemical behaviour in the studied soils, as discussed above. spatial distribution of the topsoil characteristics and pte contents (b, mn, ni, cr, pb, cu, zn, co, ba, sr) in the vineyard topsoil in this study, root mean square error (rmse) and mean absolute error (mae) were used to evaluate inverse distance weighting (idw) and lognormal kriging (lk) interpolations' performance (summarised in table 6). idw generates smoother surfaces than lk, which may decrease its performance. meanwhile, the lk method tends to underestimate the higher values and overestimate the lower values. the results indicate that lk shows an overall better performance to predict most of the examined soil parameters, except for phd.w., sand, and som contents. idw tends to compute higher prediction errors as weighting values increase. the lk outperformed the idw method for predictions made for p2o5, caco3, table 5 pearson's correlation matrix among ptes. the bold numbers denote statistically significant correlation coefficients (with p-value<0.05). b mn ni cu cr pb zn co ba sr b 1 mn 0.42 1 ni 0.99** 0.46 1 cu 0.72** 0.34 0.69** 1 cr 0.99** 0.50 0.99** 0.73** 1 pb 0.62* 0.74** 0.69** 0.44 0.71** 1 zn 0.90** 0.28 0.89** 0.72** 0.88** 0.43 1 co 0.81** 0.73** 0.83** 0.72** 0.87** 0.84** 0.69** 1 ba 0.97** 0.60* 0.98** 0.71** 0.99** 0.76** 0.85** 0.91** 1 sr 0.87** 0.59* 0.87** 0.90** 0.89** 0.67** 0.83** 0.90** 0.91** 1 *correlation is significant at the 0.05 level (2-tailed). **correlation is significant at the 0.01 level (2-tailed). table 6 performance of inverse distance weighting (idw) and lognormal kriging (lk) for predicting soil characteristics and pte contents in the vineyard topsoil. the smallest prediction errors are highlighted in bold. rmse stands for root mean square error. mae stands for mean absolute error. soil properties unit rmse mae idw lk idw lk phd.w. 0.38 0.39 0.34 0.36 phkcl 0.56 0.56 0.34 0.34 (nitrate+nitrite)-n mg/kg 0.64 0.65 0.51 0.46 p2o5 % 59.97 55.83 52.30 49.09 som % 0.42 0.44 0.38 0.42 caco3 % 0.50 0.47 0.47 0.42 clay % 3.15 3.03 2.79 2.42 silt % 3.32 3.30 2.69 2.67 sand % 4.31 5.22 3.58 4.53 coarse fraction % 11.91 11.86 11.42 11.20 ptes zn mg/kg 3.66 3.63 3.30 3.17 pb mg/kg 1.47 1.53 1.30 1.20 ni mg/kg 1.62 1.44 1.29 1.16 cr mg/kg 1.48 1.13 1.17 0.85 cu mg/kg 23.51 23.76 15.93 15.88 co mg/kg 0.60 0.58 0.58 0.52 b mg/kg 1.76 1.72 1.55 1.55 54 manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. clay, silt, and coarse fractions. furthermore, lk also showed smaller prediction errors than idw for mapping the pte contents except for cu and pb. as previously observed, the local minimum and maximum values are likely to be respectively overestimated and underestimated by lk, while the predicted local minimum and maximum values by idw are similar to the measured ones (xie et al., 2011). in the following, some maps for the selected soil properties and the b, cu and zn contents prepared by lk are displayed (fig. 2). our results confirmed that terrain significantly impact the spatial variability of soil characteristics at the plot scale. contrasting spatial patterns of soil texture can be delineated along the hillslope. the upper slope sections display higher proportions of clay and, accordingly, lower sand contents. meanwhile, at the lower half of the hillslope, high sand contents coincide with reduced clay contents. the silt and the concomitantly varying som contents are found in higher concentrations at the summit and the shoulder positions of upslope areas. at the same time, a reraising trend can be observed at the toeslope zone. by contrast, in mediterranean hillslope vineyards, the highest silt and total organic carbon contents were detected at the middle of a hillslope (rodrigo comino et al., 2016). the differences of the landscape topography and the soil characteristics may explain the observed differences. indeed, the vineyard soil in tállya is characterised by high contents of the coarse fraction (>30%), which is supposed to impact soil erosion dynamics significantly. indeed, the slope steepness and the proportions of the coarse fraction in soil are found to determine soil loss rates. at mild slope gradients (at 5°), the high contents of the coarse fraction in the form of embedded rock fragments increase water infiltration rates, thus reducing overland flow. by contrast, at higher than 10° gradients, the coarse fraction seemingly enhances runoff generation and sediment transport (gong et al., 2018). we can reasonably suppose that the coarse fraction protects the soil from excessive soil loss at the summit and the hillslope's shoulder, displaying <10° gradients (fig. 1). the main erosion-impacted zone is situated at the backslope, where high slope gradients prevail. the highest contents of the coarse fraction are observed at the backslope section, further confirming intense losses of the fine earth (< 2 mm). similarly, rodrigo comino et al. (2017) reported that the highest rock fragment contents (77%) were found at the hillslope's shoulder in a spanish vineyard. soil erosion induces particle size sorting according to the dominating sediment transport processes. sediments moved during interrill erosion, transport predominantly fine soil particles (<0.05 mm) suspended in runoff, while rill development during intense rainfall displaces coarser soil fractions (fine sand, sand) (shi et al., 2012). similar observations have been made in another sloping vineyard (nagy-eged hill, hungary), where grape rows were oriented parallel to the main slope and bare areas between rows enabled the downhill transport and the accumulation of both the fine fraction and the gravel eroded from uphill areas (nagy et al., 2012). the accumulation of sand in the footslope zone of the vineyard in tállya, together with reraising silt contents further downhill in the toeslope area, suggest that sediment grainsorting also occurs during its deposition. the displaced coarse (sand, fine sand) soil fractions are preferentially deposited right at the footslope. the fine fractions of silt and clay are transported farther downslope, increasing the silt content in the toeslope zone. in general, the spatial distribution maps of cu, zn and b show that higher concentrations are found in upslope areas, while markedly lower concentrations prevail in the backslope and footslope areas. spatial distribution of b, pb, and co present lower variability in the plot. meanwhile, zn, sr, and cr show moderate spatial variability, and mn, co, and ba demonstrate high spatial variability. their similar spatial distribution further supports the intimate association of ptes with the claysized fraction. the spatial trends reveal that the higher concentrations of ptes at the summit and the shoulder of the hillslope are associated with the low slope gradients (0-5 degree) and the high contents of the coarse fraction (that protects the soil from excessive erosion-induced losses). while the reraising pte concentrations mostly at the toeslope are likely due to the deposition of fine soil particles, mainly silt and to a minor extent clay, the main vectors of ptes during sediment transport. conclusion we have demonstrated that grape growing and, more precisely, the related use of agrochemicals significantly enriches the potentially toxic element (pte) content of soils, except for lead (pb) and manganese (mn). the slightly acidic vineyard soil in tállya (hungary) bears higher boron (b), nickel (ni), chrome (cr), copper (cu), zinc (zn), cobalt (co), barium (ba) and strontium (sr) contents compared to the local forest soil. the vineyard soil accumulated cu and – to a smaller extent – b in excess, considering median contents of these elements in hungarian arable soils as a reference. the latter is attributed to plant protection practices specific to vineyards, including frequent applications of cu-based fungicides (such as the bordeaux mixture) and micronutrient-rich fertilizers (with high b contents). anthropogenic b accumulation due to farming practices in vineyard soils within a low geochemical b area has rarely been evidenced so far. the examined soil's clay content strongly correlated with the bulk pseudototal pte contents of b, ni, cr, zn, co, ba and sr. indeed, clay-sized fractions are known carriers of ptes owing to their high metal(loid) sorbing capacities. presumably, these ptes are adsorbed primarily to clay minerals and clay mineral-organic matter complexes. a less significant correlation (significance at p< 0.05) in the case of cu and pb with the clay content presumes that additional constituents intervene in their retention in the vineyard soil in tállya. in the case of cu, the silt-bound soil organic matter (som) is also a plausible sorbing material. manganese (mn) has geogenic origin in the vineyard soil primarily. the lack of significant correlation with the soil characteristics (but phd.w.) underlines the contrasting behaviour of mn in the vineyard soil compared with the other ptes involved in the study. manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. 55 fig. 2 interpolated maps showing the spatial distribution of the topsoil contents of the (a) coarse fraction, (b) sand, (c) silt, (d) clay, (e) organic matter, (f) cu, (g) zn and (h) b predicted by lognormal kriging. pixel values were reclassified using equal intervals, which divides the range of data values into equal-sized subranges. hillslope positions are also displayed on the maps: su (summit), sh (shoulder), bs (backslope), fs (footslope), ts (toeslope). 56 manaljav et al. 2021 / journal of environmental geography 14 (1–2), 47–57. the lk outperformed the idw method for predicting the majority of soil parameters. the spatial distribution maps show higher contents of ptes at the summit and the hillslope's shoulder, while lower ranges prevail at the footslope zone. the soil samples fro m the summit and the toeslope zones have the highest contents of som, while increased contents of the coarse fraction are found at the backslope. these observations confirm that soil erosion and sediment transport processes govern the redistribution of different particle-size soil fractions, associated soil constituents and ptes within the vineyard. a better understanding of the impact of soil erosion on the spatial patterns of soil quality will advance our knowledge of erosion and sedimentation processes, which in turn will improve erosion modelling. acknowledgments i. babcsányi is grateful for the financial support of the premium postdoctoral research program of the hungarian academy of sciences. the authors wish to thank istván fekete and amanda kiss for assisting in sample treatment and laboratory analyses of samples. the authors are grateful to the local vine-growers of tállya for allowing our field survey and sharing information on the agrichemicals' use and soil management. references babcsányi, i., 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pollution estimated by different interpolation methods: accuracy and uncertainty analysis. chemosphere 82, 468–476. doi: 10.1016/j.chemosphere.2010.09.053 introduction methods and materials study area and soil sampling soil analyses pseudototal pte analyses data analyses geostatistical approaches assessment of model performance results and discussion soil characteristics and pte concentrations in the vineyard topsoil relationships between the soil pte contents and the soil characteristics spatial distribution of the topsoil characteristics and pte contents (b, mn, ni, cr, pb, cu, zn, co, ba, sr) in the vineyard topsoil conclusion acknowledgments references climate change impacts on the water resources in the danube river basin and possibilities to adapt – the way to an adaptation strategy and its update journal of environmental geography 11 (3–4), 13–24. doi: 10.2478/jengeo-2018-0009 issn 2060-467x climate change impacts on the water resources in the danube river basin and possibilities to adapt – the way to an adaptation strategy and its update roswitha stolz1, monika prasch2, michael weber1*, franziska koch3, ruth weidinger1, manuel ebner1, wolfram mauser1 1department of geography, ludwig-maximilians-universität (lmu), luisenstrasse 37, d-80333 munich, germany 2central department of information and knowledge management, bavarian state research center for agriculture, vöttinger straße 38, 85354 freising-weihenstephan, germany 3institute of water management, hydrology and hydraulic engineering, university of natural resources and life sciences, muthgasse 18, 1190 wien, austria *corresponding author, e-mail: m.weber@iggf.geo.uni-muenchen.de research article, received 14 september 2018, accepted 31 october 2018 abstract as the intergovernmental panel on climate change reported in 2013, climate change will have significant impacts on all water sectors. since water is essential for live, culture, economy and ecosystems, climate change adaptation is crucial. therefore, a legal and political framework was established by the commissions of the european union, the united nations and on national levels. for the danube river basin (drb), the international commission for the protection of the danube river got the mandate to develop an adaptation strategy in 2012 and to update this strategy in 2018. the natural science basis on which the adaptation strategy and its update are based on are two studies, conducted in 2011/2012 and updated and revised in 2017/18. numerous documents from actual research and development projects and studies dealing with climate change and its impacts on water related issues were analysed in detail and the results summarised. it is agreed that temperature will increase basin-wide. the precipitation trend shows a strong northwest-southeast gradient and significant changes in seasonality. runoff patterns will change and extreme weather events will intensify. however, the magnitude of the results shows a strong spatial variability due to the heterogeneity of the drb., it is assessed that these changes will have mostly negative impacts on all water related sectors. based on the scientific findings an approach for an improved basin-wide strategy on adaptation to climate change is developed. it includes guiding principles and five categories of adaptation measures targeting different objectives. keywords: climate change, adaptation strategy, danube river basin, water sector introduction climate change will have various impacts on ecosystems and consequently on human life (ipcc, 2007; ipcc, 2013). impacts on water will cause changes in water availability, water temperature, water quality and in extreme hydrological events like floods and droughts and accordingly trigger changes in all water related areas (ipcc, 2013). thus, adaptation to these changes will become one of the major challenges of the 21st century in river basins. in order to be prepared for possible consequences of climate change, the united nations framework convention on climate change (unfccc) asks parties of the kyoto protocol to develop implement and regularly update programmes of measures for climate change adaptation on a national and regional level (united nations, 1998). several european and un directives and guidelines are explaining the necessity of adaptation to climate change and are supporting the development of strategies (eea, 2017; ec, 2009; unece, 2009). moreover, the eu water framework directive (wfd) requires an integrated river basin management across administrative or political boundaries and demands to consider possible climate change impacts. nevertheless, adaptation strategies for the large river basins in europe hardly existed until 2012. therefore, a programme of pilot projects and a platform for exchanging experience was established to foster the implementation of transboundary adaptation activities in river basins. for the danube as europe’s second largest river basin, in december 2012 the international commission for the protection of the danube river (icpdr) adopted the strategy on adaptation to climate change (icpdr, 2013), being the first large river basin with a climate change adaptation strategy. an update will be finished by beginning of 2019. on the way to the icpdr strategy and its update, one objective is to develop a comprehensive scientific knowledge base that gives an overview of future climate change and its impact in the drb. to achieve this, a total of 89 and 73, respectively, research and development projects, studies and scientific papers were analysed. this revealed significant, regionally varying changes in all water related sectors. the second objective is to compile a catalogue of adaptation measures suitable for the drb to meet the challenges of climate change. basis for this catalogue was the analysis of already existing climate change adaptation strategies as well as close collaboration with stakeholders from the riverine countries, environmental organisations and water dependant industries. five groups of measures were identified: 14 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. preparation measures, ecosystem based measures, behavioural and managerial measures technological measures and policy approaches. the catalogue of measures is made available as a user friendly online tool. the stakeholder dialogue and the analysis of adaptation activities such as national adaptation strategies pointed out communalities, options for cooperation and challenges among the countries of the drb, which need to be further taken into consideration. to make the studies comparable, the same methods (data acquisition, uncertainty assessment) were used. the methodology of the studies and the integration of the results in the icpdr strategy on adaptation to climate change and its update are content of this publication. the study area: the danube river basin the danube is europe’s second largest river with a length of 2,857 km from its source in south-western germany to its delta at the black sea in romania and the ukraine and can be divided into the upper danube river basin (udrb) until the gauge bratislava in slovakia, the middle danube river basin (mdrb) until the iron gate at the border between serbia and romania, and the lower danube river basin (ldrb) from the iron gate to its delta (fig. 1). the catchment has a total area of 801,500 km² and encompasses several mountain areas like parts of the alps, the carpathian range and the dinaric mountains. the climatic conditions range from temperate zones in the western parts to a continental climate with hot summers and cold winters in the central and eastern basin. the southern and south-western parts are influenced by mediterranean climatic conditions with warm, dry summers. furthermore, orographic conditions also determine the climate in the drb. average temperature increases from the western parts to the eastern parts of the basin and reaches +12°c in the lowlands of the sava river, whereas the coldest temperatures can be found on the mountain peaks in the alps and the carpathians. precipitation falls throughout the year and reaches a maximum in the summer months in almost all regions except the south-western parts with long dry periods during summer. however, the amount of precipitation strongly varies in the basin between a minimum of 350 mm/a in the lowlands of the black sea and a maximum of 3,500 mm/a in the alps. the runoff characteristics change along the way through the riparian countries, determined by the passages through flat basins and mountain regions and the climatic conditions. close to its source in western germany, the danube shows pluvial characteristics which are then altered by the inflow of the rivers from the alps to a pluvio-nival runoff regime. after the influence of the inn, the danube is dominated by snowmelt, changing the regime to a single-peak mountain-snow regime with a maximum in early summer. after the inflow of rivers originating in the carpathians with a snowmelt peak in spring, and due to the continental climatic conditions with drier summers, the runoff regime of the danube shows a two-peak maximum from the carpathian rivers (first) and the alpine rivers (second), while the minimum in october is coincident. the further inflows of drava, tisza and sava result in a single maximum of the danube in april and one minimum in october. the regime characteristics of the danube do not considerably change until the outflow in the black sea. the mean average discharge of the danube increases from approximately 2,000 m³/s in bratislava, to approximately 5,500 m³/s at the iron gate and reaches finally approximately 6,500 m³/s at the danube delta, fed by the main tributaries of the rivers inn, drava, tisza and sava. the drb provides water resources for 83 million people in 19 countries (fig. 1), which makes it the most international river basin in the world (icpdr, 2014). in this region, water is used in fig. 1 main regions of the danube river basin stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. 15 various ways, ranging from agriculture to energy production and navigation. despite these important water use functions, the danube river basin is characterized by a wide range of different natural conditions, contains several highly valuable ecosystems, e.g. the unesco world heritage site of the danube delta as the world’s largest wetland and provides habitats for over 2,000 plant species and 5,000 animal species (icpdr, 2014). data base and analysis method in the following the creation of the scientific knowledge base and the methods of assessing the regional impacts of climate change on water-related issues and adaptation activities in the danube river basin (drb) are presented. on this basis the icpdr strategy on adaptation to climate change was developed. there have been two project periods. the initial danube study was conducted in 2011 and completed in 2012 (prasch et al., 2012). it provided a comprehensive overview on climate change impacts on the drb and adaptation measures. the danube study was revised and updated in 2018 (stolz et al., 2018) due to significant developments in climate modelling and new scientific findings concerning the impacts on water related issues. in this project phase only research and development projects, studies and adaptation activities which were conducted between 2012 and july 2017 were taken into account. for means of comparability the same methodology of the analysis and zoning of the drb were applied in both studies. only documents, reports and papers which have been published and are accessible through libraries or internet in english, german or french could have been taken into account. research and development projects in order to reach a common, basin-wide understanding of the scale and magnitude of climate change pressures and impacts on water resources, research and development projects and studies dealing with climate change in the drb or parts of the basin were compiled by online search and participation in conferences and meetings. for the initial danube study, 89 projects and studies were selected for the analysis. a detailed list of them can be found in the annex of the study (http://www.icpdr.org/main/activities-projects/climatechange-adaptation). for the update and revision of the danube study documents from 73 projects and studies, published between 2012 and 2017, were included (http://www.icpdr.org/main/resources/climate-changeadaptation-update-danube-study). in a first step the spatial coverage, the present status of the project (ongoing or finalized), the studied time period and the applied methods are analysed. projects dealing with climate change impacts in the entire drb were not available for the initial danube study, but the drb is part of large investigation areas of 25 projects, mostly funded by the european commission 5th, 6th and 7th framework programmes. for the update and revision of the danube study only the study from bisselink et al. (2018) was available dealing with climate change and its impacts in the entire drb. sub-regions or sub-catchments of the drb are mainly covered by projects and regional studies which are funded either internationally by the interreg programmes alpine space and cadses (central adriatic danubian south-eastern european space) as well as the south east europe transnational cooperation programme, several eu programmes, the undp (united nations development programme), wwf (world wildlife fund) and the worldbank, or nationally, in particular by germany, austria, hungary and romania. to make statements about the impacts of climate change comparable the analysis of the used climate models and the modelling periods is of utmost importance. in the analysed documents, mainly the time periods from 1961 to 1990 and from 1971 to 2000 were taken as reference period. the modelled near-future periods vary significantly, but peaking for the period 2021-2050, whereas for the far-future period there is agreement to model the time span 2071-2100. to assess the future development, models were run under scenario conditions, driven by global and regional circulation models (gcm resp. rcm), so that the spatial resolution of the simulation results varied between 0.3 and 2° (50-150 km) (gcms), and between 20 and 50 km (rcms). the ipcc sres emission scenarios a1b, a2, b1 and b2 (nakićenović and swart, 2000) were chosen and applied as single runs, sometimes as ensemble runs. some studies applied different dynamical and statistical downscaling methods to analyse the impacts of climate change in a better resolution than provided by the gcms or rcms between 1 km and 10 km. in the period from the initial danube study to its update the representative concentration pathways (rcps) (ipcc, 2013) were introduced by the ipcc to replace the sres emission scenarios. these rcps were used by some studies which are analysed for the update of the danube study. in a next step, the water related impact fields, which have been investigated by projects and studies were analysed. therefore, information on future trends of temperature and precipitation and meteorological extreme events were compiled, followed by possible effects on extreme hydrological events, on water availability and quality. in addition, possible impacts on different types of water use and land use like water supply and demand, agriculture, irrigation, navigation, water related energy production and forestry have been considered. and finally, impacts on biodiversity, ecosystems, soils/erosion, limnology and marine coastal zones in the field of ecology were composed. for the analysis, the above described data are integrated in a database. all findings were classified into statements about the entire drb, the udrb, the mdrb and the ldrb (fig. 1). commonalities, contradictions and knowledge gaps were identified and finally, the uncertainty of future statements based on the analysed findings was assessed with a newly developed approach, which is presented and discussed in this paper. adaptation activities similar to the analysis of climate change impacts on the drb, all relevant information of ongoing, adopted and planned adaptation activities in the water sector in the drb were compiled and integrated into the data base. the 16 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. national communications under the unfccc (5th or initial, 6th in the update of the study) and available national adaptation strategies provide an overview of the present and future impact of climate change and adaptation measures per country and at the eu level (unfccc, 2010; unfccc, 2014). additionally, conventions, directives or plans in relation to the eu wfd, relevant reports and further activities on the administrative level in relation to climate change impacts and adaptation activities are considered, i.e. the eea report (8/2009) “regional climate change and adaptation: the alps facing the challenge of changing water resources” (eea 2009) and eea report (1/2017) ”climate change, impacts and vulnerability in europe 2016”. a detailed list of all analysed documents can be found in the annexes of the danube studies (http://www.icpdr.org/main/activities-projects/climatechange-adaptation). in the analysis of the adaptation activities the spatial coverage, the present status of the activity (ongoing or finalized), the possible impacts of climate change and the suggested or adopted adaptation measures are studied. most activities are limited to single countries. national communications under the unfccc are available for all countries of the drb. almost all countries already adopted national adaptation strategies (nas) or are preparing one as illustrated in figure 2. conventions, declarations, guidances and programs mainly cover the entire drb or larger parts of it. the suggested or adopted adaptation measures of the activities are classified for different impact fields, analogously to the analysed impacts addressed in the analysed research and development projects. therefore, measures to adapt to changes in extreme hydrological events, water availability and quality, in different types of water use and land use like water supply and demand, agriculture with irrigation, navigation and water related energy production were considered. measures addressing biodiversity, ecosystems and marine coastal zones were composed in the field of ecology. additionally, general water related adaptation measures were also considered. furthermore, the suggested measures are classified into the categories preparation measures, general measures, ecosystem-based measures, behavioural/managerial measures, technological measures and policy approaches following the unece (2009) and the eea (2010; 2017), despite a sharp separation between these categories is sometimes difficult. in order to obtain the best possible overview over adaptation activities, the analysis was carried out in close collaboration with experts and stakeholders, e.g. representatives from state ministries for the environment, for hydrology and water management or for regional studies, from ngos such as wwf, global water partnership, danube environment forum, and water research centres and institutes, from the drb. therefore, the (preliminary) study results were discussed during meetings, workshops and conferences. uncertainty assessment projections of future climate change and its impact are always associated with uncertainties (vetter et al., 2017; latif, 2011; deser et al., 2010; hodson et al., 2012). in order to draw the right conclusions from projections of future climate change for the development of adaptation strategies, it is important to assess the uncertainty of statements from numerous studies which content different methods, areas and time periods. no method exists how to compare the different degrees of certainty or uncertainty in statements. a new and pragmatic approach was developed, attempting to give a reliable estimation of the certainty of a parameter encompassing all projects and studies regarding a certain impact. many factors are influencing the certainty of the statements about future climate change. for almost all projects and studies, different ipcc sres emission scenarios and rcps are fig. 2 countries with national adaptation strategies in the drb (as of 2018) stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. 17 applied because of different assumptions about future socio-economic development and its consequences for greenhouse gas emissions. the models applied in the studies using the sres scenarios also have varying outcomes, because of differences in the model structure, the downscaling techniques as well as the spatial and temporal resolution. this is the case for both, climatic and hydrological models. further uncertainties of the model results are related to differences in validation and analysis methods. these influencing factors of uncertainty are enlarged when analysing several studies. for each impact field a different number of statements/results are available. some issues are analysed very often, whereas for others only few statements are available. among the statements itself there are variations, adding further uncertainty. another source of uncertainty is that different documents frequently analyse different future time periods and use different reference periods. moreover, different indices, e.g. when assessing floods, are used. in order to assess the uncertainty of future climate change in this study, three variables are used. first, the statement of certainty for the analysed parameters is taken into account. second, the level of agreement among the different statements is considered and third, the total number of studies providing statements to a parameter is included. each certainty-category was calculated by the cube root of the product of the three variables presented by eight values (fig. 3). if the agreement of the statements (x-axis), the certainty information (y-axis) and the number of studies analysed (diameter of circle) are large the impact is large and the overall certainty is categorized as very high, indicated with a green colour. however, if the number of projects is high, but the agreement of the certainty statement is low, the overall certainty is medium (yellow-orange), and if all three categories are low, the overall certainty is consequently low (red). this practical approach to provide an overall certainty category to the analysed parameters allows the consideration of the, partially little, available information about uncertainty when gathering information from several projects, which apply varying methods. although this approach is simple, the resulting illustration in figure 3 enables the comparison of the certainty of the analysed parameters. nevertheless, this is a practical approach without a detailed statistical analysis, which is not possible because the available information from the analysed projects is mainly given in “soft” variables and not by numbers. figure 3 presents the revised and updated overview of certainties for projected climate change impacts of the analysed sectors in comparison to the certainties identified in the initial danube study. it has to be noted that forestry, agriculture, flood, low flow and runoff are located at the same similar certainty level, which is represented by the black dot. although there is a different amount of publications available in the two studies, figure 3 shows clearly that the degree of certainty increased significantly for most of the analysed water related issues. in the updated study, the scientific statements concerning the future development of precipitation led to a differentiation between mean annual precipitation and precipitation seasonality. it is highly certain, that seasonality changes, whereas the development of mean annual precipitation is unclear for the near future and reliable statements are only made for the far future. fig. 3 uncertainties identified in the update of the danube study (a) in comparison to the uncertainties identified in the initial danube study (b) (revision and update of the danube study, final report 2018). the legend of a also applies to b. the certainty of impacts on navigation, ecosystems and biodiversity did not improve in comparison to the initial danube study due to contradictory and vague statements. it has to be noted that not all water sectors analysed in the initial study are analysed in the update as well. reasons therefore are that an insufficient amount of new finished projects and data dealing with these topics were published in the last five years. a high level of certainty may allow the preparation of adaptation measures at an early stage and/or with more detail, whereas a low level of certainty may lead to more general types of measures (e.g. no-regret measures or winwin solutions). 18 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. results in this chapter, the results from the updated danube study are presented and differences to the initial study are highlighted. the results are solely based on the analysed studies, projects and adaptation activities that are described above. furthermore, other factors such as social, demographic, and economic development are crucial for future adaptation strategies to climate change. however, they were not subject of the present study, but are indirectly considered in the analysed scenarios. future climate change in the drb the trend of a future increase in annual and seasonal air temperature with a gradient from northwest to southeast which was identified in the initial danube study is largely confirmed by the update of the danube study. this trend is highly certain and can be regarded as a hard fact. since climate change does not stop at boarders and effects of climate change may largely vary within country borders (due to varying physiographic properties), for the update of the icpdr strategy on adaptation to climate change it was decided to show the temperature and precipitation projections of the euro-cordex project. the eurocordex ensemble runs are based on the new rcps and provide data on a resolution of 0.11 degree (~12.5km) (jacob et al., 2014). thus it is possible to draw a more detailed picture of spatially distributed temperature and precipitation trends, which in turn serves as a sounder basis for the development of adaptation measures and strategies. results from euro-cordex projections use the period 1981-2010 as reference and define 2021-2050 as near future and 2071-2100 as far future. the range of increase of annual mean temperature for the near future period is between 1.1°c and 1.5°c and for the far future period 3.6°c and 4.7°c under rcp8.5 (fig. 4). these figures show pronounced warming hotspots in mountain regions and in southeast europe. like in the initial danube study, euro-cordex projections show, that the annual (fig. 4a,b) and the summer (fig. 4c,d) temperature increases are likely to be larger than the winter temperature increase (fig. 4e,f). the drb is located in the transition zone between expected increasing (in northern europe) and decreasing (in southern europe) future precipitation. documents analysed in the update of the danube study confirm this general trend of wet regions becoming wetter and dry regions becoming drier (fig. 5). the trend is more fig. 4 change of mean annual (a, b), summer (jja) (c, d) and winter (djf) (e, f) temperature in the danube river basin for 2021-2050 and 2071-2100 according to the euro-cordex ensemble results under rcp8.5 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. 19 obvious in the second half of the century. although the mean annual precipitation in many regions will probably remain almost constant, a tendency for the next decades towards more precipitation (than in the last decades) in the northern parts of the basin and less precipitation in the southern parts is apparent (fig. 5). the general trend of wet regions becoming wetter and dry regions becoming drier is also reflected in the alpine region, where the already drier south-eastern part of austria is likely to become drier. according to the documents analysed in both danube studies, trends in mean annual precipitation are rather insignificant until the middle of the century and become significant until the end of the century. however, the most significant change is projected in seasonal precipitation distribution. the summer months are likely to become drier (up to -58%) (fig. 6) whereas the winter months show a tendency for increasing precipitation (up to +34%) (fig. 7). the numbers indicate the maximum expected decrease and increase for larger regions in the danube river basin but numbers in particular regions may vary largely. the figures display the precipitation change from the eurocordex initiative in mm relative to the reference period 1981-2010. the comparatively clearest trends are increasing winter precipitation in mountain regions and decreasing summer precipitation in regions already suffering from too little precipitation. on the other hand, there are regions where summer precipitation is projected to increase due to increased frequency of thunderstorms and short heavy precipitation events. as for temperature trends, studies that are based on the newly implemented rcps like from bisselink et al. (2018) mostly confirm previous results. furthermore, data from the euro-cordex initiative provides a more detailed picture of spatially distributed trends. fig. 5 change of mean annual precipitation in the danube river basin for the periods 2021-2050 (a) and 2071-2100 (b) according to the euro-cordex ensemble runs under rcp8.5 fig. 6 change of mean summer (jja) precipitation in the danube river basin for the periods 2021-2050 (a) and 2071-2100 (b) according to euro-cordex ensemble runs under rcp8.5 fig. 7 change of mean winter (djf) precipitation in the danube river basin for the periods 2021-2050 and 2071-2100 according to euro-cordex ensemble runs under rcp8.5 20 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. a future increase in extreme weather events is expected for the whole drb. the simulations show both, a future increase in the intensity and frequency of dry spells, hot days and heat waves, as well as local and regional increases in heavy rainfall, although the latter is uncertain in spatial and temporal localisation. for the udrb, an increased risk of storm-related heavy precipitation with high wind speeds is assumed. for the mdrb, it is expected that the occurrence of extreme precipitation days will be intensified in winter and reduced in summer. due to the warming trends for the whole basin, fewer frost days are expected in winter. generally, statements from the initial danube study are confirmed by the update. nevertheless, most recently analysed documents show a more pronounced trend towards seasonality in the occurrence of extreme events. therefore, the agreement concerning an increasing number of extreme winter precipitation events over europe and especially in the north-east for the far future period must be emphasised. statements regarding extreme summer precipitation especially in eastern europe are inconsistent. climate change impacts on water related issues in the drb the potential future climatic conditions in the drb described above will impact the water resources and water-related issues. in the following the expected main impacts on each water sector according to the analysis of the studies are described and compared in a qualitative way. as for future climate conditions, the results of the updated danube study are presented and differences to the initial danube study are highlighted (icpdr, 2012; icpdr, 2018). (1) water availability in contrast to the initial danube study, most of the documents analysed in the update expect insignificant changes in mean annual runoff until the middle of the 21st century. however, they confirm a significant decrease in mean annual runoff until the end of the 21st century. this is valid for the entire drb, also for the udrb. although this is the area with the highest water availability, water shortages are expected in unfavourable areas in the far future, which has not been reported in the initial study. the most crucial aspect regarding runoff is the change in seasonality, which applies to all of the regions in the drb. here, a decrease in summer runoff and an increase in winter runoff are expected due to shifts in precipitation seasonality. changes of runoff conditions are in turn assumed to cause a decline in groundwater storage and recharge, particularly in summer. the already monitored decline of the past in the hungarian great plain area is likely to intensify in the future. lake levels might decrease in summer. furthermore, a decrease in soil water content is likely in the drb, particularly in summer. (2) water use the described possible future changes of water availability, extreme hydrological events and water quality will influence water use. water demand is expected to increase in a warmer climate in agriculture, industry, energy production and general human consumption. in the field of agriculture more water might be required for livestock and irrigation, because of drier summers and a longer growing period because of higher temperatures. the possible shortening of the growing season due to too high temperatures in the south-eastern drb will increase the water demand for irrigation the most remarkable difference in comparison to the initial danube study is that now negative impacts of climate change on agriculture are expected to exceed positive impacts in every sub region. positive impacts like higher yields due to a longer vegetation period are now largely limited to the short and medium term future. in the far future the higher temperatures are affecting the vegetation period negatively. moreover, a higher atmospheric co2 content is no longer mentioned as a positive factor for agriculture. impacts which affect both, agriculture and forestry are a shift in species, invasive species, and pests, changing species composition and damages from extreme weather. in contrast, damages from snow and frost are assumed to be less. a changing climate will affect power generation as well. the reduced water availability in summer in combination with projected increasing water temperatures might become problematic for thermal electricity production, which is dependent on cooling water from rivers. hydroelectric power generation is likely to decrease in the drb on average and in summer, whereas in winter an increase due to more rain than snowfall is possible. however, hydropower generation in rivers may face problems due to flood events increasing in intensity and frequency and the resulting damages (frik, 2018; steininger et al., 2015). additionally, a seasonal shift in power generation might be triggered by changing water availability, above all in mountain regions. the danube is an important water way in europe. hence navigation may face challenges due to climate change effects on runoff conditions. while in winter navigation conditions might improve with less icing and higher water levels, in summer low flow conditions are likely to limit cargo loads and in worst case make the danube impassable, just as it happened during this summer and autumn. the update of the danube study shows that increasing flood conditions are expected to be problematic for navigation. possible consequences of this scenario are industrial production losses as well as increased difficulties in accessing water resources and higher costs for water resource use. also conflicts between the different water users could arise and require potential solution options as for example, a hierarchy of water supply during water scarcity periods. an increase in air and water temperature, combined with changes in precipitation, water availability, water quality and increasing extreme events may lead to changes in ecosystems, life cycles, and biodiversity in the drb in the midand long-term. the habitats and ecosystems in the south-eastern region of the drb and in the hungarian great plain area are especially likely to become drier. as consequences, a rearrangement of biotic communities and food webs, the disappearance of species and the invasion of species might occur. shifts and changes in aquatic and terrestrial flora and fauna, particularly in littoral communities and aquatic systems are likely. in the marine coastal zones, a redistribution and losses of marine organisms as well as the increase of stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. 21 invasive species and in toxic bloom events are possible impacts of rising sea surface temperatures. higher sea levels could increase the salinization of estuaries and land aquifers and change ecological conditions at the coast of the black sea. potential increasing water demand, e.g. irrigation for agricultural purposes in the entire drb, especially in the south-eastern parts, may also deteriorate the ecological and chemical balance of freshwater bodies and could lead to an increase of contaminated surface and groundwater bodies. besides climate change impacts, anthropogenic impacts, political regulations and restrictions as well as the technological development will also trigger future changes in water quantity and quality in the drb. comparing the results of both studies, the developments in climate change modelling and the resulting findings, show the necessity of an update of the scientific knowledge base, which is the basis for a successful implementation of adaptation measures and strategies. less water availability in summer is likely to cause longer, more frequent and more intense drought and low flow situation in the drb. particularly the south-eastern parts of the drb, namely the carpathian area, the southern parts of hungary and romania, the republic of serbia, bulgarian and the danube delta region are likely to be confronted with severe droughts and water shortages. contrary, there is no future trend for droughts in the alpine head watersheds. however, a spread of affected areas to the north is expected. like drought and low flow events, flood events in the drb are expected to intensify and occur more often. the update of the danube study confirms statements of the initial study. small and mountain catchments appear to be the most affected ones. with an increase of torrential rainfall an increase in flash floods is expected despite uncertainties. besides water quantity, also water quality is likely to be affected by climate change in the drb. increasing air temperature might cause increasing water temperature in the drb. this in turn will change all temperature dependent chemical and biological processes and cause reduced water quality, especially during droughts in summer. adaptation measures for the water sectors of the drb to respond to the challenges created by climate change and the water related impacts, it is of great importance to consider the consequences which today’s actions may cause as late as during the next 50 – 100 years. this needs adaptation strategies which are more ambitious than up to now. nevertheless, there is consensus between the danube countries and the european union that adaptation to climate change is a central environmental policy issue. due to the transboundary character of water and its relevance for various issues and water-related sectors such as its role for biodiversity and the ecosystem, energy, transport, agriculture, floods and droughts, integrated river basin management is key for an approach to climate change adaptation. in this section, possible adaptation measures for the impacts of climate change on the water sector of the drb as suggested by the analysed adaptation activities are presented. measures with a high common agreement are selected. this means that they have been suggested by most of the analysed documents. furthermore, they are valid for almost all impact fields. adaptation should start with a priority on win-win, no-regret and low-regret measures that are flexible enough for various conditions. the adaptive approaches require enough flexibility so they can also be modified and adapted to local conditions. this way of working has the benefit of increasing resilience and decreasing vulnerability for the whole danube ecosystem. the adaptation measures can be classified into five different categories, targeting different objectives. preparation and technological measures are aiming on monitoring and infrastructural issues; eco-system based measures should enhance the capacity of eco-systems to adapt, whereas behavioural and managerial measures aim to raise awareness and to encourage knowledge exchange. policy approaches are most important for basin-wide transboundary solutions. table 1 gives an overview on these measures. they are classified in the different categories, introduced above. the smoothly formulated measures allow various realisations and there is no sharp separation possible between the categories of the measures. however, the measures not only have overlapping fields and linkages between the categories, but they are also linked between affected sectors and other relationships such as upstream – downstream dependencies. positive and negative effects among them may be possible and conflicts may occur, even though the selected measures are no-/ low-regret or win-win-options, so that they have positive effects whatever the extent of future climate is, or other social, environmental or economic benefits are also met (european climate adaptation platform, 2018). for instance, the expansion of protection areas as ecosystem based measure and policy approach could be conflicting with the construction and modification of infrastructure as technological measure, albeit environmental issues are likely to be considered in the adjustment of infrastructure and synergy effects might be found. an increase in water retention areas can lead to higher groundwater recharge, a reduction of flood peaks and positive effects for biodiversity, so that various sectors may profit such ecology with enabling biodiversity, navigation with reduced flood peaks or water related energy production with reduced losses during a flood. to prevent possible conflicts and to foster common goals, cross-sectoral, interdisciplinary and integral approaches and continuous communication, also among the danube countries are necessary. furthermore, the time horizon of the effects of adaptation options should be taken into account. while the long-term measures, e.g. reforestation, affect water retention not until several decades, short -time measures, e.g. water-saving techniques may be immediately effective. besides the presented measures, there are numerous options for adaptation to climate change, particularly for distinct sectors. the spatial coverage for applying adaptation measures ranges from local to catchment wide actions. in many cases coordination among bordering countries is of great necessity. the principal obstacles to 22 stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. install adaptation measures documented are a lack of knowledge, trained staff, reliable data and financial resources. for a detailed listing of adaptation measures it is referred to the danube study (2012) and the update of the danube study (2018). to make the large number of measures better usable for stakeholders, an easy to use online toolbox is created. the toolbox allows the user to obtain detailed information on the measures of interest, which are divided into various groups such as impact fields, relevancy to the wfd, time horizon and others. conclusion and outlook climate change will affect water resources in all parts of the drb as the analysis of existing studies and research and development projects shows. despite all water sectors and regions are affected, the effects of climate change vary depending on the region. this is due to the landscape diversity as well as the huge east-west and north-south gradient in the drb. therefore, adaptation measures have to be flexible enough to react to these heterogeneities. to deal with the uncertainties that come along with projections of future climate we presented a pragmatic approach to show the related uncertainty of the future development to the analysed climate parameters and impact fields. the update of the danube study confirmed the trends detected in the initial danube study., the improved climate models and modelling approaches (euro-cordex) substantiate the results of the first danube study. temperature and precipitation development can be depicted in a higher resolution and with a higher certainty. impacts of climate change on water related issues will be even more significant in almost all water sectors along with a stronger negative trend than in the first study. the new certainty analysis shows a significant increase in certainty for most of the water sectors. temperature development and seasonality in precipitation even tend to be highly certain. despite all heterogeneities, climate change affects all regions and does not stop at national borders. water connects all riverine countries, which is why a common strategy is highly important for a successful adaptation to climate change effects. being a frontrunner and pioneer among transboundary river basin commissions in climate change adaptation activities, the icpdr adopted the first icpdr strategy on adaptation to climate change in the year 2012. basis therefor was a table 1 common adaptation measures to climate change impacts in the water sector in the danube river basin (icpdr strategy on adaptation to climate change 2018 in preparation) preparation measures additional, intensified monitoring activities to follow and assess climate change and climate change impacts homogenous data production, digital mapping and a centralised database for data exchange and comparability among regions and countries identification of potential risk areas and hot spots implementation of forecasting and warning services (e.g. for extreme events such as floods and droughts) development of action plans or integration of specific issues into ongoing planning activities (e.g. to deal with water scarcity and flood situations) further research to close knowledge gaps, determine vulnerability or reduce uncertainty rules for water allocation in case of water scarcity under the aspect of benefit sharing toolbox preparation measures ecosystem based measures taking environmental implications and the conservation of biodiversity into consideration in all other measures sustainable management of land use practices for improving resilience, and for enhancing the capacity to adapt to climate change impacts implementation of green infrastructure to connect bio-geographic regions and habitats protection, restoration and expansion of water conservation and retention areas rehabilitation of polluted water bodies behavioural and managerial measures support education, capacity building, awareness raising, information exchange and knowledge transfer establishment of and support for an integrated risk management support of a water saving behaviour propagation of best practice examples application of sustainable methods (e.g. good agricultural practices) technological measures adjustment of (existing) infrastructure, e.g. construction and modification of dams and reservoirs for hydropower generation, agriculture, drinking water supply, tourism, fish-farming, irrigation and navigation development and application of water-efficient technologies efficient wasteand sewage-water treatment and water recycling policy approaches support of an institutional framework to coordinate activities harmonisation of international, basin-wide legal limits and threshold values implementation of restrictions (e.g. for development in flood risk areas) expansion of protection areas (e.g. for drinking water resources) adaptation of policies to changing conditions stolz et al. 2018 / journal of environmental geography 11 (3–4), 13–24. 23 comprehensive overview about future climate change in the drb and its impacts on the water sectors as presented in the previous sections. moreover, it was necessary to collect and analyse already existing adaptation strategies and actions. in order to get the most comprehensive overview possible, experts and stakeholders were consulted additionally. at the danube ministerial meeting in february 2016 ministers asked the icpdr to foresee an update of its strategy. during the development of the update of the icpdr strategy on adaptation to climate change in 2018, the following points emerged as highly relevant and have to be taken greater into account. first, the strategy needs to be developed in close collaboration with stakeholders, experts and country representatives. this increases acceptance and fosters the implementation. second, the strategy is developed as a reference document that may be used by countries, regions, and organisations to develop their own individual adaptation strategy. in this context, we developed an online toolbox, which provides a huge amount of adaptation measures. third, clear goals of the strategy need to be defined in order to make it more powerful. fourth, the strategy is considered to be a “living” document. this means that it will be updated regularly in order to include the latest scientific results and experiences with the strategy. the principal objective is building resilience against climate change impacts on water resources through capacity building, transboundary cooperation and encouraging basin-wide approaches as well as benefit-sharing is a key priority and objective to address climate change in the danube river basin. base is the update and revision of the danube study. despite most of the results regarding climate change and its impacts from the initial study could be confirmed, science made advances in climate modelling allowing for more detailed climate change projections. this is particularly important for the highly heterogeneous drb. along with this, uncertainties could be decreased, which is highly relevant for planning and taking adaptation measures. moreover, the continuous dialogue with experts, stakeholders and country representatives allowed identifying strengths and weaknesses of the existing strategy. strengths are that it represents the first existing overall guideline for adaptations in a large catchment and gives an overview on climate change and its impacts in the entire drb. in contrast to the strengths it shows no clearly addressed objectives and contains no summary for policy makers. during the initial danube study as well as during the update some shortcomings had to be faced which made it quite challenging to create a comprehensive scientific database for an adaptation strategy in the drb. a meaningful comparison of documents about climate change or adaptation was made difficult, since documents were not available, not available in english, or did not fulfil scientific standards. for some parts of the drb there exist almost no studies about climate change and its effects on the water sector. comparability was even made more difficult by the fact that methods and data used in the analysed documents are highly diverse and standards are not met. moreover, international and interregional collaboration and also collaboration between institutions within one country could be expanded. when it comes to the implementation of adaptation measures, it has to be considered, that measures in one sector may have retroactive, positive or negative effects on one or more other sectors or even other regions or countries. to prevent possible conflicts and to foster common goals, cross-sectoral, interdisciplinary and integral approaches as well as trans-regional/national agreements are necessary. integral approaches also aim to enhance synergy effects which should be sought. an example of a synergy effect is an increase in water retention areas which can lead to a higher groundwater recharge, a reduction of flood peaks and positive effects for biodiversity. the updated icpdr strategy on adaptation to climate change and the web-based toolbox provide a significant improvement. it increases the applicability of the strategy and gives the stakeholders support for the development of regional and national adaptation solutions. furthermore, it underlines the necessity of transboundary and trans-sectoral collaboration and emphasizes the importance of specific adaptation measures depending on the characteristics of the subcatchments. acknowledgements we gratefully acknowledge the financial support by the german federal ministry for environment, nature conservation and nuclear safety (bmu) within the danube studies and the icpdr for the update of the strategy. we thank the members of the international commission for the protection of the danube icpdr for fruitful cooperation and discussions within its various groups. the participation of experts and stakeholders of the drb in the workshops is also acknowledged references bisselink, b., bernhard, j., gelati, e., adamovic, m, jacobs, c., mentaschi, l., lavalle, c., de roo, a. 2018. impact of changing climate, land use, and water usage on water resources in the danube river basin. eur 29228en, publications office of the european union, luxemburg, 74 p. commission of the european communities 2009. white paper adapting to climate change: towards a european framework for action. com(2009) 147, brussels deser, c., adam, p., vincent, b., haiyan, t. 2012. uncertainty in climate change projections: the role of internal 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(eds) 2015. economic evaluation of climate change impacts. springer, 499 pp. stolz, r., weber, m., ebner, m., mauser, w. 2018. revision and update of the danube study. integrating and editing new scientific results in climate change research and the resulting impacts on water availability to revise the existing adaptation strategies in the danube river basin. final report. 115 pp. available via https://www.icpdr.org/main/sites/default/files/nodes/documents/cli mate_change_adaptation__update_danube_study_final_report_20180607.pdf cited sep 2018. unece, 2009. guidance on water and adaptation to climate change. available via http://www.unece.org/fileadmin/dam/env/water/publications/d ocuments/guidance_water_climate.pdf. cited 20 aug 2014 unece, wmo 2010. guidance on water supply and sanitation in extreme weather events. available via http://www.unece.org/fileadmin/dam/env/water/whmop2/wh o_guidance_ewe_ final_draft_web_opt.pdf. cited 20 aug 2014 unece, 2015. water and climate change adaptation in transboundary basins: lessons learned and good practices. 128 pp. unfccc, 2010. annotated outline for fifth national communications of annex i parties under the unfccc, including reporting elements under the kyoto protocol. available via https://unfccc.int/files/national_reports/annex_i_natcom_/applic ation/pdf/nc5outline.pdf. cited 20 aug 2014 united nations, 1998. kyoto protocol to the united nations framework convention on climate change. available via http://unfccc.int/kyoto_protocol/items/2830.php. cited 14 nov 2013 vetter, t., reinhardt, j., flörke, m., van griensven, a., hattermann, f., huang, s., koch, h., pechlivanidis, i.g., plötner, s., seidou,o., su, b., vervoort, r.w., krysanova, v. 2017. evaluation of sources of uncertainty in projected hydrological changes under climate change in 12 large-scale river basins. climate change 141 (3), 419–433. doi: 10.1007/s10584-016-1794-y http://www.icpdr.org/main/resources/danube-declaration-2010 https://www.icpdr.org/main/activities-projects/climate-change-adaptation https://www.icpdr.org/main/activities-projects/climate-change-adaptation http://www.icpdr.org/main/climate-adaptation-strategy-adopted http://www.icpdr.org/main/climate-adaptation-strategy-adopted http://www.icpdr.org/main/danube-basin/river-basin.%20cited%2020%20aug%202014 http://www.icpdr.org/main/danube-basin/river-basin.%20cited%2020%20aug%202014 http://unfccc.int/kyoto_protocol/items/2830.php introduction the study area: the danube river basin data base and analysis method research and development projects adaptation activities uncertainty assessment results future climate change in the drb climate change impacts on water related issues in the drb adaptation measures for the water sectors of the drb conclusion and outlook acknowledgements references spatial development of the 1507–1510 plague in poland and its consequences. kalisz district case study journal of environmental geography 13 (1–2), 1–12. doi: 10.2478/jengeo-2020-0001 issn 2060-467x spatial development of the 1507–1510 plague in poland and its consequences. kalisz district case study tomasz związek* department of geoecology and climatology, stanisław leszczycki institute of geography and spatial organisation, polish academy of sciences, twarda 51/55, 00-818 warsaw, poland *corresponding author, e-mail: tzwiazek@twarda.pan.pl research article, received 27 december 2019, accepted 28 february 2020 abstract the article discusses the causes and effects of the plague which is said to have spread over many polish towns in 1507. the focus is on its possible causes, related to the occurrence of droughts and floods in central europe in the late 15th and early 16th century. available sources from the late mediaeval period have also been analysed for the recorded perceptions of the extreme climatic and weather conditions. special attention has been paid to the issues of intensity and spatial distribution of the effects of the plague on the example of one district. the analysis covered a variety of issues such as settlement changes, prices of basic goods or even some pollen data. the main results of the study indicate that the climatic extremes at the turn of the 16th century exerted a long-term impact on the society and economy of the region. they also contributed to the abandonment of settlements on rural sites. keywords: historical geography, plague, late medieval poland, spatial distribution, droughts, floods, weather extremes introduction according to the present state of research, the lands of poland were not affected by the black death in the 14th century (guzowski et al., 2016), however various parts of the country were regularly struck by plagues, which appeared and subsided at quite steady intervals (karpiński, 2000; walawender, 1957). according to scholars, their outbreaks are connected to the occurrences of natural disasters, such as droughts, floods, hail, flooding, frosty or warm winters, which contributed to crop failures, rise of food prices and, consequently, famine, which weakened the overall condition of the society (karpiński, 2000). a good example to illustrate this point was the great plague of cracow, which was probably a long-term consequence of the drought of 1540 and which in the period between july and november 1543 took the lives of at least 10 thousand persons (which constituted roughly 1/3 of the city’s population) (follprecht and noga, 2014; sowina, 2016). similarly, in western europe, numerous periodic plagues appeared at steady intervals and were also likely related to various weather extremes or climatic changes. one particularly difficult time, abundant in plagues, was the period of armed conflicts in the 17th and 18th centuries, which was also the coldest period of the little ice age (maunder minimum) (alfani, 2013; alfani and percoco, 2019; curtis, 2016; owens et al., 2017). records contain accounts of economic and demographic consequences of the plagues (campbell, 2016; cummins et al., 2016), but attention should also be paid to their socio-cultural dimension (martín-vide and barriendos vallvé, 1995). thus, the investigation of the causes and effects of the plagues should be considered one of the fundamental topics in the study of the history of former societies as well as the history of climate and environment. however, recent works have shown that the pre-industrial society (mainly agrarian) was able to deal with crises quite efficiently (büntgen et al., 2011). they became problematic only when a sudden accumulation of extreme events (natural disasters, famine, wars, etc.) took place, which disturbed every-day balance of the society (haldon et al., 2018). study of extremes and their potential consequences – plagues – are, therefore, complex and interdisciplinary by nature, touching upon various research fields. the basic ones include studies on the problem of disease spread, social reactions to plague, temporary practices of depopulating villages, towns, etc. (lagerås, 2016). such studies refer both to the spatial and to the environmental aspects, all of which were as important as the economic elements. the fundamental question which thus arises concerns the relationships between individual crisis events, both climate and disease-driven. the main aim of this article is to discuss three major research problems: 1) the extension of the plague in the context of the climatic and weather extremes which contributed to it; 2) the changes to the spatial distribution of the plague on the basis of a case study of the district of kalisz; 3) the duration of the plague and its impact on the economy of the said area. answers to the formulated research questions will be given based on the analysis of some of the available materials from the southern part of the greater poland region (fig. 1). for this area, some of the oldest preserved tax registers are available – for the years 1507–1510 – offering lots of data concerning the spread of the disease (związek, 2013). as regards the extension of the plague, i am assuming that its level can be calculated using a couple of indices: 1) the number of deceased and isolated 2 związek 2020 / journal of environmental geography 13 (1–2), 1–12. people; 2) the number of fugitives from urban and/or rural sites; 3) the degree of abandonment of fields and villages; and 4) the fluctuations of the economic indicators. the plague of 1507 – written evidence chronicles feature numerous pieces of evidence confirming that in 1507, the kingdom of poland was struck by a plague which affected many towns („per multa oppida poloniae pestis erat”) (walawender, 1932). the plague reached as far as vilnius (in the great duchy of lithuania); it was also recorded in far rus’ – in novgorod – and in silesia, where it appeared in 1507 and slowly captured subsequent parts of the region together with the towns located there. it struck wrocław (breslau) and its vicinity, claiming lives of many people between september 1507 and the beginning of january 1508. examples based on chronicle mentions can be easily multiplied, but they cannot represent the exact severity of the occurring disease (apart from the frequently exaggerated narratives). neither are we able to specify its nature. it could have been the pestilence or typhoid – historical sources are very imprecise in this respect (karpiński, 2000). the severity of the disease given in the narrative sources as well as in sources related to taxes seems to suggest that this was a contagious disease, the germs of which were transmitted between humans and/or animals. one of the chronicles of novgorod recorded in 1508 that in this year in the city over 5000 men and women died („w lěto 7016, pomre ljudi mużska połu i żenska tma i 5000 dusz’ i 400 bez czetyrech czełowěk”, (walawender, 1932). the number should not be taken literally but rather as a proof that this was indeed a great plague, exceeding the comprehension abilities of the contemporaries. in this respect, chronicle sources are by no means able to offer us a precise picture of the epidemic. plague as a possible consequence of climatic and natural hazards according to christian pfister’s preliminary model of the economic impact of climatic events (pfister, 1988), it is very likely that the outbreak of the plague at the beginning of the 16th century in poland could have been, at least partly, a long-term effect of weather events in the preceding years. in short, they had created a climatic pressure (e.g. great hunger) which, in subsequent steps, could have led to another crisis, such as the plague (ell, 1985; kiss, 2020). the issue is, however, more complicated, and it is also connected with the land use changes over time as well as the scale and range of human impact on the environment during the period of the development of the so-called german law in central europe. recently archaeologists have pointed out that intensified land use, forest clearance as well as increase in crop production and breeding strongly affected the daily life of the medieval and early modern societies (schreg, 2011, 2019). in this model, intensive anthropopressure led to microclimatic changes, where floods, droughts or heavy rains were becoming more noticeable in daily life. for instance, extremes such as floods could have caused high soil erosion and bring about the long-term effect of food production drop, rendering the society more vulnerable to diseases. high water could have also caused serious pollution that was dangerous for people and animals, ultimately leading to development of typhoid fever, cholera, etc (who). fig. 1 study area in the context of the past and contemporary poland with modern neighbouring states. basemap source from naturalearthdata.com związek 2020 / journal of environmental geography 13 (1–2), 1–12. 3 hungarian and czech context recently kiss (2017) has shown that some source materials on hungary definitely point to the occurrence of a drought in 1502 and 1503. she has also indicated that the dry year 1502 had contributed to the aggravation of the consequences of the drought in the following year, which is especially visible in the old world drought atlas (owda) model (cook et al., 2015). this was a period of particularly destructive hail storms and crop failures – affecting cereals, vine and honey alike. in this case, as demonstrated by kiss (2017), bees ‘may act as indicator of weather-, and probably (spring-summer, or earlier) drought-related problems’. on the other hand, data from the eger diocese from 1506 have shown that many agricultural fields and vineyards were destroyed within its borders; the income from the tithes was significantly smaller; there was a shortage of fish. it has also been proven that subjects in general suffered from poverty. thus, the calamities which affected hungary at that time were complex, and their occurrence can be traced thanks to many types of written records as well as environmental indices (proxies). on the territory of the czech crown, the beginnings of the 16th century were not recorded as an extremely dry period (brázdil, dobrovolný et al., 2013). narrative sources mentioned very cold winters at the turn of almost every year and frequent spring floods. like in the rest of central europe, in 1503 a 30-days drought and low level of crops were recorded. the subsequent years (1505, 1506 and 1507) were also described as periods of drought brázdil, kotyza et al., 2013). according to the decadal frequencies of droughts in the czech territory (brázdil, dobrovolný et al., 2013), we can describe the beginning of the 16th century as a period of sinusoidal weather changes with frosty and long winters, frequent floods in springtime and repeatable drought period in summers. sources the main sources which have been used in this study can be divided into two basic groups: written records and climatic/environmental archives (tree rings and pollen data). the written sources consist of narrative data (chronicles, memories), which can also be treated as literary texts; this means that they can be used in the context of climatological research only with difficulty due to the personal reception of the phenomena by the authors. the main collection of narrative texts used in this study came from the book by walawender (1932). the main idea behind his research was to offer as comprehensive view on the climate history and changes as possible based on the contemporary set of published sources. the biggest advantage of this book is that the second part of each volume has been supplemented by the author with extensions from various source editions. thanks to this, walawender’s works help one reach the basic material and compare his climatic interpretations with the original records written in old-polish, old-german, latin and old-russian. another source of materials were the tax registers from the 16th century, which were obtained from the central archive of old records in warsaw (agad). the registers from the districts of konin and kalisz were included in the archive unit no. ask i 12. the tax registers contain information about the main settlement structure of the late jagiellonian period of the polish crown (słoń, 2011). they also provide a lot of valuable economic and demographic data on the rural sites and towns of the early modern state (gieysztorowa, żaboklicka, 1955; boroda, 2007; boroda, guzowski, 2016). nevertheless, the basic sources were the oldest, and unpublished, tax registers (1507–1510) from southern greater poland. the environmental archives which were used in this study consist of the tree rings data model from the ‘old world drought atlas’ (odwa) (cook et al., 2015) and preliminary pollen data from one of the peatlands in central greater poland (czerwiński et al., 2019). the pollen data had been collected for one of historical and environmental projects in poland, and at the time when i was doing my research, only one set of proxies (kazanie peatland) had been elaborated and, therefore, available for me to use. the main difficulty with pollen data concerns the chronology of such materials. in the kazanie peatland, the resolution of the core appeared in 10-year intervals, hence the analysis made it possible to look only at the beginning and the end of the plague period. secondly, in general, the data from peatlands are strictly limited to the nearest study area, up to 5 or 10 km away from the reservoir (birks, birks, 1980; theuerkauf, couwenberg, 2017). for this reason, the final results are more local than in the case of analysis from lake cores. however, the pollen database from polish lakes and peatlands, which is worthy of application in historical research (with proper 14c chronology), is expected to grow (cf. with izdebski et al., 2016) methodology the main methodological idea behind this research was to understand, both in spatial and quantitative terms, the mutual relations between climatic or environmental events (in this case mostly droughts and floods as well as their shortand long-term effects) and the history of the past societies. in this approach, i intend not only to examine past events, but also to pursue some recent climate history research proposals (camenisch, 2015) which deal with narrative sources as primary materials for the investigation of past climate changes. my main assumption has been to describe and analyse one fairly well-known example of a crisis using the methods of spatial and economic analysis and to compare the preliminary results with the accessible proxies from recent projects published in poland. in this case, the final result would not be very comprehensive, mostly because of the lack of source materials and proxies at this stage of research. the general idea is also in line with the direction of landscape change studies connected with climate research (among others, the analysis of the process of abandonment of settlements). results owda – climatic event and tree-rings data a comparison of the weather conditions in hungary, czechia and in poland at that time (owda) indicates clearly that in the years 1501–1504, there could have been a long-lasting drought (cook et al., 2015). this scenario 4 związek 2020 / journal of environmental geography 13 (1–2), 1–12. can be supported by weather observations from cracow (limanówka, 2001), which show that at that time, the weather was perceived as rather chilly (in the spring) or warm (in the summer). none of the spring days in the years 1503–1507 was considered extraordinarily warm, while days of heat in the summer constituted a tiny fraction of all the observations: in 1503 – 5%, in 1504 – 3%, in 1506 – 11% and in 1507 – 16%. the significant accumulation of dry years in the late 15th and early 16th century (fig. 3) is also visible in the last studies using treerings data from poland (przybylak et al., 2019). looking at the narrative sources in this period, there is much more data pertaining to floods mainly sudden ones occurring on the main rivers of the kingdom (the warta, the vistula) (walawender, 1932). it should be noted, however, that the information about the dry periods, even though theoretically more acute in poland than in hungary, did not translate to the reception of these events in the written records in poland, in which there is a major gap between before 1500 and after 1505 (fig. 3). in this period, the number of chronicle mentions was bigger for floods (fig. 2) than for droughts, so one can assume that the perception of the late medieval polish society could have been more sensitive to all water-connected weather events (such as floods, heavy rains, hail storms). despite the hard weather conditions, the last decade of the 15th century could not be treated in poland as a breakthrough (cf. with camenisch, 2018). it is likely that especially the period of very intensive floods and droughts and related with them other weather extremes of approx. 1500–1507 can be treated as the starting point of the later plagues (fig. 4) in the first decade of the 16th century (kiss, 2019, 2020; yue, lee, 2020). the weather extreme from the sight of the tax records the long-term drought, confirmed in all central europe (kiss, 2017, 2019; kiss, nikolić, 2015; brázdil, dobrovolný et al., 2013) together with numerous instances of flooding caused by sudden rains, had most likely resulted in the outbreak of the epidemic in the kingdom of poland and great duchy of lithuania in 1505 (walawender, 1932). starting from this year, the plagues repeatedly struck the polish territories in the subsequent fig. 2 potential relationship between data from written records (vertical bars) on floods in poland and owda. sources (cook et al., 2015) and (walawender, 1932) fig. 3 potential relationship between data from written records on droughts (vertical bars) in poland and owda. sources as in fig. 2 -6 -5 -4 -3 -2 -1 0 1 2 3 4 1490 1493 1496 1499 1502 1505 1508 1511 1514 p d s i year pdsi_pl pdsi_hu pdsi_cz -6 -5 -4 -3 -2 -1 0 1 2 3 4 1490 1493 1496 1499 1502 1505 1508 1511 1514 p d s i year pdsi_pl pdsi_hu pdsi_cz związek 2020 / journal of environmental geography 13 (1–2), 1–12. 5 decades of the 16th century. when analysing the data from the district of konin, one can clearly see that information about the disease was recorded in tax-related sources in three main ways: 1) direct mention about the plague striking villages (e.g. “medius mansus per pestem desertus est”); 2) mentions of peasants fleeing in connection with the disease (“duo mansi … per profugos deserti sunt”); 3) information about peasants dying (“tribus mansis deserti sunt a tres annis per mortem kmethonis”). thus, we are dealing with consequences of a persisting disease given in sources post factum. such data do not make it possible to determine specifically when the disease broke out. it is only clear that it happened in the summer-autumn months of the year. the analysis of the yearly distribution of data from the period 1507–1510 (fig. 5) from the district of konin shows that the disease was most acute in the early autumn (september) of 1507 (gochna, związek, 2019). it was then that the greatest percentage of flights and deaths due to the disease was recorded, however it was not until one year later that the greatest part of arable fields became unused. in 1509–1510, the plague was clearly subsiding to practically disappear in the autumn of 1510. observations based on the data from the konin district suggest that in this case, we are dealing with consequence-laden diseases (in all likelihood, contagious), which in the view of the contemporary people were so lethal that they forced peasants to flee from their farms. escape was generally quite a common means of dealing with plague; it was commonly practiced by the contemporary societies (karpiński, 2000; sowina, 2020). in the context of the phenomena in question, however, the manner in which the contemporary tax offices of the state recorded such information seems to be of more importance. in the 15th and 16th century poland, every village was obliged to pay mandatory, extraordinary taxes, which were set as lump sums. in general, taxes were paid on the basis of the cultivated land, forest clearance, water and windmills. the amount of the main tax burden in relation to the income was not large (guzowski, 2005), however failure to pay it was punished with imposition of a penalty upon the entire village (as a community of residents) which in the late 15th and early 16th century amounted nearly 60 times as much as the initial fee per one łan (latin: mansus) of cultivated land (gochna, związek, 2019). for this reason, in the preserved tax registers, tax clerks paid a lot of attention to record the reasons for failure to pay the tax by individual villages. in tax registers from different districts, such information was recorded in various ways. fig. 4 information from written records about diseases in poland (vertical bars) with data on droughts or wet periods from owda. sources as in fig. 2 fig. 5 information about the disease in 1507–1510 in the konin district with causes of field desertion. source: agad, ask i 12 -6 -5 -4 -3 -2 -1 0 1 2 3 4 1490 1493 1496 1499 1502 1505 1508 1511 1514 p d s i year pdsi_pl pdsi_hu pdsi_cz 6 związek 2020 / journal of environmental geography 13 (1–2), 1–12. while in the konin district, each entry in the tax register was accompanied by an appropriate comment, in its southern neighbour – kalisz district – such notes are not to be found. it is rather puzzling that as far as the registers from kalisz are concerned, the source sheets often include blank fields (fig. 6). an analysis of all such fields from the registers from 1507–1510 (table 1) suggests that they should be interpreted as a direct testimony to the plague spreading over the district. the villages struck by the plague did not pay taxes because the peasants ran away (or possibly died) (non habet kmethones) or the villages were simply deserted (desertum). a quantitative analysis has made it possible to note that the plague in the vicinity of kalisz – unlike in the konin district – was a constant threat for 3 years, from 1508 to 1510, with practically identical impact on the settlement structures (approx. 30% of all villages remained empty). fig. 6 fragment of a tax register page from 1507 with two empty records. source: agad, ask i 12, f. 11v plague and the roads network tax registers also make it possible to study the spatial development of the plague. using the available data concerning the settlement in the 16th century poland (polish territories of the crown in the 16th century. spatial database, 2015), one can trace the distribution of the villages affected by the plague in the period in question (table 1, fig. 7). due to its transit character, the district of kalisz communicated the areas of lesser and central poland (provinces of sieradz and łęczyca) with western greater poland and german duchies; it also played an important role in the north-south dimension (from pomerania to silesia) (związek, 2017). wiping the plague out from the outbreak sites – especially given the high mobility at that time – was a very difficult task. the disease affected most acutely the central and eastern parts of the district. the persistence of the disease in this area should also be connected to the existence of a relatively dense and old settlement network, which originated in the early middle ages (dunin-wąsowicz, 1960). when analysing the map of the development of the plague in the district, it makes one wonder why the plague did not affect so much the areas located to the north-west of kalisz. the only reasonable explanation of this phenomenon is the proximity of the prosna – a river splitting the district into two equal parts. it runs through the district from the south-east, via kalisz, to north-west, supplying the warta near pyzdry, and then heading for poznań. this means that a large portion of the contemporary transit (of items and people) must have been completed using the prosna, which must have helped mitigate the effects of the plague in this area (fig. 7). economic impact background – crops prices in cracow in many western researches, climatic events are explained using data on fluctuations of crops prices (campbell, 2016; pribyl, 2019). however, there is no collection of prices of basic agricultural products available for greater poland for historical periods. the best and most comprehensive sets have been elaborated for cracow (pelc, 1935), warsaw, lublin and gdańsk (cf. with boroda, 2019). due to its state-of-the-art character and the retained source base (e.g. price series for warsaw start only from 1526 or 1540–1545), only prices from cracow – as the most important city in the southern part of the crown – have been used here (fig. 8). prices from lublin have been preserved only starting from the second half of the 16th century, while the market of gdańsk was connected more with the economic situation in amsterdam and other hanseatic cities than with the rest of the polish state. the dataset for cracow is not complete and includes many gaps but the prices of rye can suggest that some kind of fluctuation occurred between 1499 and 1507. it is possible that the price fluctuation was caused by climatic pressure, however without further examples table 1 quantitative comparison of data concerning entries in tax registers from the kalisz district from 1507–1510. source: agad, ask i 12 register [year] w/ potential rate number no. of entries no. of all villages no. of deserted villages (desertum) no. of all empty entries percentage of empty entries a b c e e/aˣ100% 1507 601 434 25 66 11% 1508 518 431 30 129 25% 1508 (rents) 543 422 23 164 30% 1509 499 430 28 136 27% 1510 (i) 460 419 11 132 28% 1510 (ii) 471 424 13 144 30.57% związek 2020 / journal of environmental geography 13 (1–2), 1–12. 7 from other cities in the region (czechia, hungary, slovakia) and other studies on prices in poland in the later centuries, this observation cannot be treated as certain. fig. 8 recorded prices of oats and rye between 1490 and 1515 in cracow. source: (pelc, 1935). in towns the investigation of the impact of the plague upon the economy of the kalisz district is heavily constrained. there are no comparisons of crop prices available for this area. changes to the economic structure can be traced using the data included in tax registers or data on potential fluctuations of the prices of rural property (villages, village parts, individual fields, etc.). while the analysis of tax-related data is relatively easy, analysing the prices of property poses problems related to the amount and partial dispersion of the available source material (gąsiorowski, 1970; pośpiech, 1989). such studies also call for a much broader context (territorial and temporal). the data on the spreading plague can also be studied from the perspective of the economic power of towns in the given district. for years 1507–1509 and 1552, we only have data concerning the liquor tax (polish: czopowe, literally – bung tax) (table 2), which was a tax paid on the propination – the exclusive right to produce alcoholic beverages in the towns (and sometimes villages) of the former crown (boroda, 2016). the data indicate that the plague exerted an unfavourable impact on all the towns of the district, as the income from the liquor tax dropped in 1508 (in relation to the previous year) by approx. 20%. this state of affairs was not long-lasting though, as in the subsequent years the total income from the tax exceeded the amount from before the plague by approx. 6%. on the other hand, when one inspects the impact of the plague on the towns in the context of their overall social, demographic, economic and institutional potential (słoń, 2017), it turns out that the smaller towns (s) within the district could experience the effects of the plague to a significantly smaller extent than the large (l) and medium (m) towns, such as kalisz, pleszew or stawiszyn. in the times of plague, small towns could successfully compete fig. 7 the spatial development of the plague in kalisz district villages (1507–1510) according the main roads network. source ask i 12 8 związek 2020 / journal of environmental geography 13 (1–2), 1–12. with the past production leaders, increasing their own production. the increase in their production could be driven by migrations of craftsmen – temporary escape from one town to another. however, this supposition has not been confirmed in the urban sources for the region. in a longer perspective, it is visible that during the first half of the 16th century, the main urban centres of the district failed to maintain their position. there was a significant economic dispersion in this area, which benefitted small towns, whose economic potential grew in 1552. it is not clear, however, to what extent this effect was caused by the plague of 1507, because there are no sources for the period between the plague in question and the liquor tax register of 1552. table 2 amount of the liquor tax from the towns of the kalisz district in 1507–1509 and 1552. source agad, ask i 12 town / year classification 1507 1508 1509 1552 kalisz (capital city) l 13200 10076 12432 6721.5 pleszew m 1716 1264 1428 864 stawiszyn m 1046 786 3791 2100 sulmierzyce s 228 127 168 864 koźminek m 226 259 0 768 zduny s 222 58 0 192 iwanowice s 124 132 126 318 dobrzyca s 117 146 66.5 519 raszków m 91 596 69 150 odolanów s 88 70 74 96 sobótka s 48 160 48 96 kwiatków s 29 37 13 192 ostrów wielkopolski s 20 70 49 216 total (in grosze) 17155 13781 18264.5 13096.5 the possibility that the polish economy of the late 15th and early 16th century functioned in the state of the so-called late mediaeval crisis (guzowski, 2008) is firmly rejected. instead, it is argued that this period was one of prosperity, lasting without interruptions from the end of the war against the teutonic order (1466) until the so-called deluge (1655–1660) – a period marked by the catastrophic war against sweden. as far as this interval is concerned, the vast majority of polish towns were small or medium-sized (bogucka, samsonowicz, 1986). some towns (reaching 1–2 thousand residents) were clearly agricultural, which was evidenced not only by the small share of crafts and trade, but also by the functioning of a limited economic market in their closest vicinity and existence of many inner gardens (intra muros). it appears that this relatively weak urban structure on the polish territory, disadvantageous in the longer perspective of overall economic development of the country, made it easier to deal with the effects of natural disasters – mainly plagues. it should not come as a surprise that kalisz, being a medium-sized town and the centre of the region, was most seriously affected by the consequences of the plague in 1507–1510 (fig. 9). on the other hand, smaller towns benefitted from the situation at this time, offering population running from bigger towns a safe refuge. in the countryside the plagues might also cause the significant landscape changes resulting, for example, desertation of arable land or entire villages (żytkowicz, 1969). in this respect tax registers offer an opportunity to observe the spatial spread of the plague in the countryside areas of the kalisz district. as far as the general tendencies are concerned, one can see that the size of the agrarian land (latin: mansus, polish: łan) in peasants’ [polish: kmieć] and village leaders’ [polish: sołtys] farms decreased year on year (fig. 10). the effects of the plague were becoming more severe, as in the period between 1507 and 1510, approx. 18% of all peasants’ farms were completely deserted (schreg, 2020). the median of the abandonment of the remaining villages in the district was 0.33% of the agrarian land. the crisis affected over half of the villages in the kalisz district – 186 villages can be considered affected by the disease (52% of all). their łan area dropped from 4.25 łan to 2.5 (median). in the case of 128 villages (36% of all), no direct correspondence with the plague effects has been noted. it has also been observed that for 40 villages (11% of all), an increase in the number of łans was recorded between 1507 and 1510 (the median of the number of łans from 3 to 4.5). the available data for the kalisz district do not make it possible to make specific judgements concerning the immediate impact of the disease and its consequences. apart from following directly from the peasants’ death, the phenomena in question could have resulted from their flights as well. the countryside could have also been suffering from overall economic slow-down in this period. it is particularly interesting to note that the unused fields were taken over by neighbouring peasant farms and this practice was of considerable size. data from pollen (kazanie peatland) in spite of the foregoing, it should be noted that written records alone cannot render the full picture. what can be done about localities for which no tax registers have been preserved? they too were probably struck by the plague; the question is: to what extent? in order to extend the scope of the analysis, some palynological data have been included which can also reflect the economic changes brought about by the plagues with the accompanying transformation of the past landscapes (mordechai et al., 2019; słowiński et al., 2019). the peatland is located almost 100 km away from kalisz, but it can significantly contribute to the data on landscape changes for areas for which we do not have any quantitative written records (in this case gniezno and poznań districts). to this end, in order to illustrate the problem and offer a preliminary interpretation, one palynological site was selected, namely the kazanie peatland (fig. 1), which reflects environmental changes of a local character (czerwiński et al., 2019). the chronology of the site was prepared in a 10-year resolution; thus, the paleoecological observations can be made for the period before the climatic extreme year 1505 and after a few-years spread of the plague in the związek 2020 / journal of environmental geography 13 (1–2), 1–12. 9 polish kingdom. however, these limited data can offer us the first preliminary look at the environmental and economic impact of the plague on the rural sites in central poland. at present, this is the only site in greater poland available with reliable abso lute chronology and continuous palynological sampling (improving time-resolution of paleoenvironmental interpretation) described by a joint team of historians and paleoecologists. on the basis of the preliminary materials prepared at the kazanie site (fig. 11), one can see (in particular based on the anthropogenic indicators, like cereals and meadow fig. 9 increase in income from the liquor tax in 1508 in relation to 1507 – as a percentage. source agad, ask i 12 fig. 10 decrease of the number of arable land in kalisz district during the plague 1507–1510 with comparison of 1564. source: agad, ask i 12 and (kuc et al., 2015). 10 związek 2020 / journal of environmental geography 13 (1–2), 1–12. pasture plants) that at the beginning of the 16th century, there was a small drop of the pollen share in the analysed samples. it was not rapid, however, reaching for example approx. 1% for cereals in the interval ca. 1501–1511 and nearly 2% in the interval 1501–1521. there is also an almost simultaneous increase of meadow and pasture pollen share, which could indicate the considerable size of the practice of abandoning cultivated fields and transforming them into areas not used in the production of grain crops. one can also note the long-term drop of the percentage value of ruderal plants, which accompany humans’ settlement in the given area. particularly relevant proxies are pollen of cereal and ruderal plants, which declined around 1511. simultaneously, the level of birch pollen, which is a pioneer species, was rising. in this case, the paleo-proxies should be applied in combination with the written records (abandonment of settlements and fields) in another region. comparing paleo-data with written evidence, one can assume that the settlement changes in the kalisz region can be interpreted as a long-term result of the plague, and also, indirectly, as the result of the climate changes during the little ice age (cf. with schreg, 2011; white 2014). a detailed analysis of the palynological data from other sites with reliable absolute chronology of sediment would make it possible to offer more accurate observations connected with the reaction of rural communities to all sorts of extreme events – including the plague. the kazanie fen discussed above offers an example which is limited in terms of range, as it applies at maximum to an area within several kilometres from the site centre. a larger reservoir could even show processes on a regional scale. secondly, a bigger body of water from which pollen data could be extracted would also be less prone to local environmental transformations (e.g. forest clearing). the observations from the kazanie peatland are promising when it comes to the use of pollen data analysis in the study of changes brought about by plagues, floods, or droughts in historical-environmental research. but in order to develop a comprehensive narrative about the direct impact and relations between human societies and local environs, it is necessary to build a substantial database of paleo-archives. conclusion and research perspectives the article has demonstrated that simultaneous application of quantitative and spatial research approaches makes it possible to achieve a deeper understanding of the studied phenomena. furthermore, the employment of data obtained from nature archives allows one to conduct analyses in a more complex manner. as far as the description of the phenomena in question is concerned, mentions from narrative sources have been proven to be exaggerated. the manner in which they present information is also affected by the problem of the individual perception of the described events – which is difficult to account for. the preliminary analysis of other materials (mainly tax-related and natural) has shown that indeed one can speak of the spread of the plague in the polish territory at the beginning of the 16th century. its impact on rural and urban communities was visible in written records (the growing number of deserted villages and fields) and in paleo-data. in particular, the pollen data analysis has shown that settlement abandonment and economy drops in the rural sites can be observed after approx. 1511. what is definitely needed are further studies of the reactions of pre-industrial societies to various climatic and weather extremes causing plagues. in the subsequent steps, we should focus on the possibility to correlate the data on plagues with the trade in rural property. the same should be carried out for urban areas as well. the analysis of the polish territories should be extended to cover other provinces – for example rus’ and mazovia. it would also be advisable to consider the problem of potential economic fluctuations in individual towns within the polish territory more broadly. fig. 11 simplified pollen data from kazanie peatland in 10-year resolution. source (czerwiński et al., 2019) 0 5 10 15 20 25 30 35 40 1461 1471 1481 1491 1501 1511 1521 1531 1541 1550 p o ll e n i n p u t (% ) year (cal. bp) pine (%) oak (%) birch (%) hornbeam (%) medows and pastures (%) cereals (%) ruderal plants (%) związek 2020 / journal of environmental geography 13 (1–2), 1–12. 11 in the polish literature so far, the postulated economic fluctuations have been attributed, among others, to the crisis of feudalism and the resulting general crisis of production in the pre-industrial economy; this seems to call for a reinterpretation. a new approach to the study of factors which shaped the economic changes should consider the mutual relations between the former societies and the changes of environment and climate. acknowledgements i would like to dedicate this article to all the friendly people whom i met during my scholarship at the central european university in budapest in the spring of 2019. it is with great pleasure that i recall my meetings especially with prof. józsef laszlovszky, edit sárosi, leslie carrriegel, and jános incze. i would also like to thank michał słowiński, urszula sowina, piotr guzowski, sambor czerwiński, adam kozak, agnieszka mroczkowska, dominika łuców, michał słomski and ewa wółkiewicz for valuable subject matter-related advice. i am also very grateful to stanisław butowski for english translation and language corrections of this article. the research was funded using means from the national programme for 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(2020). drought-induced spatio-temporal synchrony of plague outbreak in europe. the science of the total environment 698, 134–138. doi: 10.1016/j.scitotenv.2019.134138 związek, t. 2013. najstarszy rejestr poboru nadzwyczajnego i szosu z 1507 roku z terenów powiatu konińskiego. rocznik koniński 18, 173–201. związek, t. 2017. drogi. in chłapowski, k. and słoń, m. (ed.) wielkopolska w drugiej połowie xvi wieku. instytut historii pan. warszawa, 268–290. żytkowicz, l. 1969. studia and wydajnością gospodarstwa wiejskiego na mazowszu w xvii wieku, warszawa. państwowe wydawnictwo naukowe. introduction the plague of 1507 – written evidence plague as a possible consequence of climatic and natural hazards hungarian and czech context sources methodology results owda – climatic event and tree-rings data the weather extreme from the sight of the tax records plague and the roads network economic impact data from pollen (kazanie peatland) conclusion and research perspectives acknowledgements references the feasibility of cooperation to comply with land use change obligations in the marosszög area of south hungary journal of environmental geography 11 (3–4), 37–47. doi: 10.2478/jengeo-2018-0011 issn 2060-467x the feasibility of cooperation to comply with land use change obligations in the marosszög area of south hungary gábor ungvári1*, zsolt jolánkai2, andrás kis1, zsolt kozma2 1regional centre for energy policy research, water economics unit, corvinus university of budapest, fővám tér 8, h-1093 budapest, hungary 2department of sanitary and environmental engineering, budapest university of technology and economics, műegyetem rakpart 3, h-1111 budapest, hungary *corresponding author, e-mail: gabor.ungvari@uni-corvinus.hu research article, received 18 september 2018, accepted 31 october 2018 abstract in many years excess water inundations generate a major obstacle to farming in the lowland part of hungary, including the marosszög area. diverting water to large distances requires an infrastructure that is costly to develop and maintain. alternatively, low-lying local land segments could be withdrawn from cultivation and utilized to collect the surplus water. the ecological focus area (efa) requirement of the eu points to the same direction: it requires that 5% of arable land is converted to other, ecologically more beneficial uses. during the research project it was tested if it is feasible to apply a novel economic policy instrument, an auction to trade land use change obligations, to achieve the efa requirement in a cost effective way through the cooperation of farmers, while also creating a practical solution to manage the seasonal surplus water cover on land. the research was carried out in an interdisciplinary way: a dynamically coupled fully integrated hydrological model, including surface and subsurface modules, was applied by engineers to better understand the interconnections of land use, local hydrology and the role of the water diversion infrastructure; while a pilot auction exercise was conducted by economists with the participation of farmers to understand if cost reductions can be achieved through cooperation, as opposed to individual fulfilment of efa obligations. the analysis also revealed which segments of the water diversion network are economic to maintain. it was confirmed that it is possible to improve local water management and satisfy the efa requirements at a reduced cost if appropriate economic incentives are applied to trigger the cooperation of farmers. keywords: inland excess water, land use adaptation, agriculture, economic instruments, water management infrastructure, auction introduction seasonal water surpluses appear in the tisza valley not only as floods, but also as temporal water coverage and water logging in low lying areas that are otherwise protected from floods (van leuween et al., 2008). these excess water occurrences are slow but complex hydrological extremities, which affect surface and subsurface soil conditions (szatmári and van leuween, 2013). they frequently occur due to meteorological, morphological, land cover, pedological and hydrogeological characteristics (pásztor et al., 2015) as well as a result of anthropogenic factors (farkas et al., 2009; benyhe and kiss, 2012). to mitigate the unfavourable agricultural and infrastructural effects of excess water, an extensive defense system of hydraulic structures mostly pumps and weirs -, and a 42,400 km long channel network is maintained in the lowland parts of hungary (kozma and koncsos, 2011). the benefits provided by water diversion are not commensurate with the otherwise rather elusive maintenance and defense costs (pinke et al., 2018). there are several explanations for this. after 1990 land ownership and land use changed, earlier large farms that had consisted of thousands of hectares of intensively cultivated mono-culture, were replaced by medium and small sized farms, frequently with a size of only a few dozen hectares, lowering the efficiency of agricultural activities. the price signals provided by commodity, e.g. grain, markets replaced the earlier centrally set prices, introducing revenue risk to farmers. central budget resources provided for network maintenance have been gradually lowered, reflecting fiscal difficulties as well as a shift in priorities. a shrinking resource base alone may not necessarily be problematic, fragmented land ownership, on the other hand, requires large scale cooperation, which only worked in some exceptional places, typically with the involvement of the local water management associations. while the state slowly withdraws its resources from the field (vtosz, 2011), half-heartedly it continues to contribute to the maintenance of the water management system (ovf, 2016, chapter 5.5.2), thereby maintaining a false image that excess water drainage for agriculture is a public task. practical experience, however, suggests that the systems cannot be maintained and operated on previous high levels due to the shrinking financial resources. in theory, there are two main types of solutions. 1) farmers would have to contribute substantially to the financing of the infrastructure. they are hesitant, however, because they do not any more believe that high quality services would be provided in exchange for their 38 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. payment. it is also uncertain if their increased payment would be justified by improved productivity. 2) the networks would need to be scaled back to a lower size that is easier to maintain from currently available resources. this also requires a parallel change in farming activities, as parcel characteristics would change in locations where the network is abandoned. furthermore, the actual network modifications need to be determined, but this type of optimization requires information on the adaptation possibilities of farmers, which is not readily available to the managers of the water network. the goal of the research was to test if the second option (shrinking the network to ensure that it is in line with reduced financial resources) can be pursued through innovative policy solutions in a way that is efficient both economically and from the perspective of altered land use. the ecological focus area (efa) requirement of the eu was picked as the driving force of change as it requires that 5% of arable land is converted to other, ecologically more beneficial uses (viaggi and vollaro, 2012). farmers were involved in a pilot exercise in which they participated in a hypothetical market where they were allowed to trade the efa obligation with each other. in other words, farmer a could pay farmer b so that the latter fulfils the efa obligation of farmer a by converting his own land. as a result, transformed land would not need to be served by the water management infrastructure any more, while it was expected that compliance with efa would become cheaper. in addition, it was important to understand exactly which land parcels would be transformed away from intensive agriculture, to see if this shift is in harmony with local hydrological conditions. to support information on the latter, a hydrological modelling analysis was carried out for the study area. study area the pilot area of the study is in the marosszög geographical region in the south of hungary, along the last stretch of the maros river before it reaches the tisza river. the geographic area under study (fig. 1) is an approximately 120 km2 large watershed delineated by the maros river on the south, by the sámson-apátfalvy-szárazér on the east, an irrigation channel on the north and the makói main channel on the west. it belongs to the great-plainand within that to the alsó-tiszavidék geographic area. makó town also lies within the perimeters of the area. the terrain is flat, the maximum altitude difference is less than 10 meters and ranges from 75 m to 85 m above baltic sea datum. however, the area has a slope towards west and south, as the receiving water body is the maros river on the south-west of the area. the origin of the terrain is related mainly to fluvial activity, but eolian originated loess formation can also be found on the north-eastern part of the area (deák, 2012). the maros river played the major role in the formulation of the terrain in the holocene, which has been ceased by the river regulations of the early 20th century. old river-reaches and oxbows can be found on the area, which are prone to collection of runoff. the textural types of the top soil are mainly loam, with a clay-loam intrusion from the north-west. this pattern partially stands for the deeper layers as well; fig. 1 modelled pilot area with altitudes and the modelled channel network ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. 39 however, in a large part of the eastern-middle part of the area the particle size distribution of deeper layers (> 3 meters depth) is dominated by the relatively larger fractions, as it is the alluvial deposition of the maros river, generally known as coarse sand (deák, 2012; pásztor et al., 2015). the area has a continental climate, with significant seasonal variations and large temperature range. the measured minimum temperature in the last century at szeged (omsz) was -29.1 °c, the maximum was 39.7 °c, the coldest month is january, with an average temperature of -1.3 °c, the hottest month is july with an average temperature of 21.8 °c. the average yearly precipitation is 532.2 mm, the wettest month is june with 67.4 mm and the driest is january with 29.6 mm on average. the number of sunshine hours ranges between 1700-2400 per year. the average yearly actual evapotranspiration is 500550 mm (vituki, 1972). at present 80-83% of the study area is in agricultural use, of which 98% is used for intensive agriculture (crops and vegetables), reaching a historical peak after centuries of adaptation. the area is moderately, but regularly (every 3-5 years) affected by excess water inundation. methods the methodological concept the research was designed as a participatory process with the involvement of farmers from the pilot area in the marosszög. the local water management association (tisza-marosszög vízgazdálkodási társulat, timavgt, www.timavgt.hu) ensured that farmers became aware of the research project and they were willing to contribute to it, thereby incorporating local knowledge and experience into the analysis. decision on land use/crop choice is based on a balance of productivity and the cost of maintaining necessary conditions for the production. these decisions are frequently distorted because the different subsidies together with the compensation against the losses due to external natural circumstances usually override the need for adaptation to the natural local endowments of the land. this is reasonable on the production level of individual farmers, while such an economic frame may be considered irrational by many who see the adverse effects of such policies. this contradiction supports the outsiders’ view that there is no way to discuss common issues with farmers in a truly rational way. the aim of the research was to create a situation where farmers’ land use adaptation / crop choice decisions are inspected in a coherent economic frame in order to test the hypothesis that as opposed to individual, farm level optimization, the cooperation of farmers results in 1) better overall financial outcome for them and 2) a land use pattern that better suits local conditions. this hypothesis was tested by creating a decision sphere based on a perceived “threat” from a then upcoming eu regulation. this policy process was the common agricultural policy (cap) regime to enter into force in 2014, which originally envisioned a 7% requirement for ecological focus areas (efa) as part of pillar i green payments. later this number was lowered to 5%, and exemptions were also provided, but within the research the 7% value was used. from an agricultural production point of view, the efa regulation is a forced reduction of the production intensity. compared to the prior status quo, it generates an unavoidable burden in the form of revenue reduction for the farmers as they switch to lower revenue land use or lower value crop (the research did not deal with the net effect of the regulation including environmental gains that could be positive). the efa regulation was applied in the research because it meant a credible future change for the farmers, therefore the possible ways to mitigate its negative effect proved to be a sensible “down to earth” question to them, offering a suitable common ground for discussions. the economic approach was supported by hydrological simulations carried out for the pilot area, which served a better understanding of the magnitude, coverage and dynamics of the unfavourably saturated soils and surface inundations. in the absence of precise and detailed monitoring data, the simulation results of the inundations were verified by the field experience of farmers. this discussion also proved useful to create a common understanding and bonding between the researchers and the farmers. in a later stage of the research 1) the economic information that was gained from the test of the economic policy instrument and 2) the inundation frequency and coverage information of the hydrological simulation was combined to identify the financially sustainable and unsustainable elements of the channel system. below the hydrological as well as the economic methods are described in detail. applied instruments – hydrological simulation the goal of the hydrological simulation was to understand the effect of the drainage channel network on groundwater, soil moisture conditions and surface water coverage frequency. the model calculations also helped to relate the drainage network to land use and to compare it with the judgement of farmers on which parcels are most likely to be converted from agriculture to efa in case of external regulatory requirements. various climate, water governance and land use scenarios were also tested to see the sensitivity of results. the detailed spatio-temporal simulation of excess water inundation poses a number of challenges. small relief, undrained sinks and the flow modification effect of surface water coverage prohibit the usage of methods purely based on flow hierarchy. both surface runoff calculations and instream flow routing are necessary, as water movement can be neglected neither on terrain nor in the complex drainage network. in case of excess water, the subsurface processes are as important as the surface accumulation (kozma et al., 2014). finally, the abovementioned processes occur simultaneously and influence one another. up to date, only fully coupled/integrated hydrological models (daniel et al., 2011; van leeuwen et al. 2016) are 1) appropriate to deal with such complex hydrological phenomenon and 2) to analyse different water governance scenarios. 40 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. in this research the waterisk integrated hydrologic model (wr ihm) was applied, which was developed with the aim to study the hydrologic extremities (flood, excess water, drought) dominant in the low land parts of hungary (kozma and koncsos, 2011; jolánkai et al., 2012). the wr ihm is a distributed parameter, fully coupled hydrologic model. it simulates the major processes of the local-regional hydrologic cycle in parallel: precipitation processes (rainfall, interception, snow accumulation), evapotranspiration, channel and overland flow as well as unsaturated zone and shallow groundwater movement. the physical basis of the algorithm means that arbitrary climatic-land use-water governance scenarios can be set up through the adjustment of model elements (channel network, pumps, weirs), boundary conditions (e.g. precipitation, temperature time series) and model parameters (e.g. cropspecific surface roughness, leaf area index and root zone depth) (kozma et al., 2012). the simulations result in a temporal series of maps for all modelled components (surface water coverage, groundwater levels, stream and channel depth profiles, etc.). furthermore, the quantitative description of flow and storage processes enables the application to calculate comprehensive volumetric water budget. this covers all surface and subsurface components and processes involved in the model system (e.g. channel discharges, pumped volumes, groundwater-channel interaction, infiltrating fluxes, evapotranspiration, surface water coverage). these features make the waterisk application a substantial support tool for decision-making. for the current analysis the model has been set up with a 50 by 50 meter grid (resulting in ~48000 computational cell), driven by the available digital terrain model, also 50x50m resolution (fömi, 2012). the channel network has been recreated in its whole extent, including the secondary channels, but not including the ditches along the agricultural plots. approx. 125 km of channel have been included in the model. channel crosssections and longitudinal sections have been provided by the local water authority (lower-tisza-district water directorate alsó tiszavidéki vízügyi igazgatóság http://www.ativizig.hu/), including weirs, and pumping stations, with operation levels. as current roughness values were not available (only consultations with local water managers) a relatively rough manning value of 0.05 have been used uniformly on the channel network for current conditions. this has been supported by site visit experience. the channel system drains the szárazér channel gravitationally, and at high flow conditions the makó pumping station lifts the collected excess water from the channel into the maros river. land cover was derived from the corine land cover maps (eea, 2013). precipitation data were also given by the local water authority for over 10 stations in the area for the 1998-2000 period. precipitation, temperature and relative humidity data for the 1991-2000 period for the szeged station was provided by the national meteorological service (országos meteorológiai szolgálat https:// www.met.hu/en/idojaras/). due to the complexity of the described processes and limited data availability, the formal full calibration of the model is not viable. instead some of the key hydrological variables have been used to manually adjust the defining model parameters. such hydrological variables are the measured groundwater levels and scattered and uncertain field observations of water coverage patches. the state of the groundwater table plays an important role in the water cycle of the area. water coverage extent and durations for example show high sensitivity to groundwater depth (koncsos et al., 2011). therefore, it is important to set the model parameters well in order to give proper groundwater table simulations. there are only two groundwater monitoring wells located in the economic auction pilot area, both being in makó. thus a larger area has been included in the hydrological model to include two more groundwater well time series to the calibration process. we expressed the agreement of measured and simulated groundwater level time series with common model efficiency criteria (moriasi et al., 2007): the pearson correlation coefficient (r2), the root mean square error (rmse) and the nash-sutcliffe model efficiency (nsme). scenario development in the second phase of the project, scenario development was undertaken to generate a framework of the model simulations and to create a basis for the interpretation of the model results. we considered several alternatives for the three main affecting factors: climate, water governance scenarios and land use. instead of setting up all the possible combinations, based on expert judgement we chose the 15 most relevant climate-water governanceland use variants. climatic scenarios: the ipcc sres a2 and b2 emission scenarios (ipcc, 2000) were selected to examine the effects of possible climatic changes of the next 100 years on the water budget of the pilot area. these two scenarios have significantly different emission trends regarding the main greenhouse gases, therefore they have been selected to provide a range of possible changes, given that the uncertainty of the predictions is high. in the marosszög pilot area the climate scenarios were implemented as simple temperature, precipitation and relative humidity time series for the 2070-2100 period. these time series were developed by different regional climate models, applied by the prudence project (christensen, 2005). three such climate model results were examined and compared locally to the measured time series of the control period. these were hadley centre adeha, adehb, adehc data, the sweden’s meteorological and hydrological institute’s (smhi) results and the danish meteorological institute’s (dmi) data. both annual precipitation and seasonal distribution were compared. the comparison shows that there are huge variations between the modelled climate data for either annual sums, averages or seasonal distributions. based on this, we decided that two climate models will be used for certain hydrologic simulations. hadley centre adeha data was selected to drive the wr-ihm model for all of the examined scenarios, and dmi was selected to drive certain model scenarios in order to see the range of effect that the driving data can cause on the model outcome. all together six climate scenarios were set up, ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. 41 named as c1 – control period, c2 – ipcc a2, c3 – ipcc b2, and their combinations with the hc adeha and dmi model results. water governance scenarios: four scenarios were developed for water governance. the first (wg1) is taking the assumption that the maintenance of the drainage system (fig. 1) will be on the same level as today. the second case (wg2) assumes that there are no channels on the area, which was developed to give a reference for the effectiveness of the channel network. the third water governance scenario (wg3) was developed in order to simulate the effects of a water retention focused water governance on the whole water budget of the pilot area. for this a simple weir system was implemented on the drainage network, without any sophisticated regulation mechanism. this variant represents an extreme solution for 1) avoiding groundwater drainage and 2) implementing channel storage, even at the price that it would often cause flooding in many areas. the last scenario (wg4) was an optimistic case, assuming that there will be more funding for maintenance of the channel network in the future. in this scenario, an increased conveyance capacity of the channels was modelled by setting the manning roughness of the channels to the typical value of well-maintained channels. land use scenarios: three versions were developed regarding the land use of the pilot area. the current land use (lu1) where simplifications have been applied to the corine database. 18 classes were set up all together, agriculture being the largest coverage. suburbs of makó town also cover a significant area, while natural vegetation is small (wetlands). for future scenarios, forests were inserted to the model in places where significant water coverage durations were modelled. under lu2 scenario 7% of the area was changed from agriculture to forest, while under lu3 scenario around 12% of the agricultural vegetation was changed to forest. applied instruments economic exercise the economic policy instrument proposed for the marosszög area is a market to trade land use change obligations, implemented through an auction (weikard et. al., 2012) that can promote the common fulfilment of the efa requirement by several farms together. it helps farmers to select the actual pieces of land for conversion, while also serving as a payment mechanism from beneficiaries (farmers whose land continues to be used for crop production) to those land owners whose land is converted. under the concept farmers bid a portion of their land for land-use change, supplying a price tag for compensation. the farmers whose bids are accepted receive the equilibrium price from the auction for each hectare. the compensation is paid from a fund to which the owners of unconverted land have to contribute, equally after each hectare. initially 32 farmer interviews were carried out in order to gain an in-depth understanding of local issues and perspectives on farming and ecology, and to distribute initial information about the project. the discussion resulted in a conciliated excess water inundation map of the area that served as the basis of common understanding of the issue. then the concept was explained in detail, followed by an auction, and finally sharing and discussing results. all of the meetings were assisted by professional facilitators to make sure farmers remained motivated through the process and they understood the presented concepts. on hypothetical examples it was illustrated that cooperating with each other can lead to an overall lower cost than if each farmer fulfilled the requirement on its own. it was explained how a farmer with good quality land and high yields can pay another farmer with low quality land to fulfil the 7% obligation for the both of them in a way that is beneficial for both parties. the farmers understood this mechanism and afterwards the economic instrument (the auction) was described. during the exercise farmers bid a portion of their land for land-use change, supplying a price tag for compensation. the actual portion depends on the farmer. some farmers may offer all of their land, while others may not bid at all, knowing that they would be paying someone else to change their land use instead. farmers may bid different pieces of their land at different prices. those farmers that did not wish to participate in the bid, did not have to, they would then carry out the required land use conversion on their own land. from the bids a supply curve is constructed showing the marginal cost of land use change (ungvári and kis, 2013). this curve is used to determine the equilibrium price of converting the required number of hectares. the farmers whose bids are accepted would receive this equilibrium price for each hectare. the compensation is paid from a fund to which the owners of unconverted land have to contribute, equally after each hectare. the owners of unconverted arable land receive a dual benefit: they pay a lower price to other farmers than the opportunity cost of conversion (= lost profit) on their own land, and the local water balance may also improve. the owners of converted land receive revenue from other farmers as part of the economic policy instrument, and fetch some land use benefits (e.g. profit from grazing; revenue from timber), possibly coupled with a payment under the common agricultural policy. before the auction, the farmers needed to be well informed about these cash flows. the owners of converted land will not any more generate revenue from intensive crop production, but – since they submit lower than average prices at the auction – this displaced revenue can be safely assumed to be lower than the average for the marosszög. in other words, areas with low productivity are converted, while areas of higher productivity remain intensively cultivated. 22 farmers with total cultivated land of 1778 hectares participated in the exercise, a little less than 20% of the case study area. 2 farmers, with 76 hectares, decided that they would not engage in the cooperation, that is, they would rather change land use on their own plots, as they had some low quality land, and likewise, they would refrain from offering the land use change service as part of the auction exercise, even though they were aware of the potential financial benefits. their decision was likely due to lack of trust in the smooth operation of the scheme or limited understanding of the concept. the results of the economic exercise contributed to a simplified cost-benefit analysis in which the costs of maintaining the channels were compared to the benefits 42 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. quantified as the profits generated by the agricultural activity enabled by shifting the land-use change obligation to other plots of land. both the costs and benefits were assessed as annual values. results hydrological model calibration main tendencies of the measured groundwater levels have been described reasonably well by the model, however some of the extreme water levels were either under-, or overestimated in different parts of the area. table 1 highlights the model efficiency values of the three considered monitoring wells for the 1998-2000 period (note that in case of groundwater table simulations we haven’t find any widely accepted guidelines for model performance in the literature). the simulation provided moderately good performance in the agricultural areas for földeák and gencshát wells, while inadequate for makó well located in the settlement. in latter case, possible ignored local effects (water withdrawal and concentrated infiltration, impervious areas, etc.) can explain the bad performance. further information about the model set up and calibration is found in jolánkai (2013). table 1 model efficiency measures of groundwater levels for the calibration period 1998-2000 model efficiency measure groundwater well gencshát v209 földeák 2322 makó 2433 r2 0.74 0.93 0.32 rmse 0.78 0.49 0.79 nsme 0.45 0.41 -1.30 figure 2 shows the observed and simulated relative changes of water level relative from the beginning of 1998. groundwater level during the 1999 excess water flood is underestimated by the model, while the next year the simulated level follows reasonably well the trends of measured water table changes at the földeák monitoring well. there is no comprehensive satellite or aerial photograph based water coverage data from the area, therefore the justification of model results has been carried out in an untraditional way. within the frame of the project, local stakeholder forums have been held to discuss future landscape management options and to assess the validity of economical tools to support future decisions with regard to management options. during these forums the local farmers were asked to evaluate the simulated maximal water coverage map. the result of this qualitative assessment is shown in figure 3. the general opinion of the farmers about the spots of water coverage has been reaffirming. there have been spots however, where the model showed water coverage that was not confirmed by farmers. also there have been areas, where they could not give feedback, as they did not have relevant knowledge. the farmers also indicated areas where water coverage had been experienced, but the model did not show any sign of water on the surface. the overall conclusion is that the order of magnitude of the water coverage is well estimated, while the fine spatial distribution of ponds is not so well described. given that the soil structure of the area is rather inhomogeneous, this is not so surprising. hydrological simulations as table 2 shows, water coverage extent varies on a wide range if all the scenarios are treated together. however, if the effects of climate change, land use change and water governance change are being examined separately, a different picture emerges. climate change has the strongest effect on the water coverage. compared to c1, the area of water coverage in the affected areas drops to about 11 % of the total area on average in scenarios c3. scenario c2 shows an enormous drop of water coverage (14.2 to less than 1%) according to the hc model, which may seem unrealistic. the dmi model shows a more than 50% rate of change in average water coverage in scenario c3, which is larger than the similar value for the hc similar results. it is likely that the real change would be between these values, given that the real climatic conditions are between the two regional climate model predictions with respect to the control period. the fig. 2 calibration results for the földeák groundwater well – relative change of the measured and simulated water table ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. 43 fig. 3 confirmed modelled maximal water coverage (1998-2000) by the local farmers in the marosszög pilot area table 2 water coverage durations (km2) and the proportion of the coverage of the whole area (%) according to the investigated scenarios (hc: hadley centre adeha data, c1: control period, c2: ipcc a2, c3: ipcc b2, wg1: current water governance, lu1: current land use) scenarios duration of coverage [days] total [km2] proportion of the whole area [%] 0-7 7-14 14-21 21-28 28-60 60-365 hc-c1-wg1-lu1 14.6 1.7 0.4 0.1 0.1 0.0 17.0 14.2 hc-c2-wg1-lu1 0.9 0.0 0.0 0.0 0.0 0.0 0.9 0.8 hc-c3-wg1-lu1 13.1 0.1 0.0 0.0 0.0 0.0 13.2 11.0 hc-c1-wg1-lu3 15.0 1.6 0.3 0.1 0.1 0.0 17.0 14.2 hc-c1-wg1-lu2 14.7 1.7 0.3 0.1 0.1 0.0 16.9 14.1 hc-c2-wg1-lu2 0.9 0.0 0.0 0.0 0.0 0.0 0.9 0.8 hc-c3-wg1-lu2 13.1 0.1 0.0 0.0 0.0 0.0 13.2 11.0 hc-c1-wg3-lu1 15.0 1.8 0.3 0.1 0.2 0.5 17.9 15.0 hc-c1-wg2-lu1 25.6 2.4 0.5 0.2 0.2 0.0 28.9 24.2 hc-c1-wg4-lu1 14.5 1.7 0.4 0.1 0.1 0.0 16.8 14.1 hc-c2-wg4-lu1 0.9 0.0 0.0 0.0 0.0 0.0 0.9 0.8 hc-c3-wg4-lu1 12.9 0.1 0.0 0.0 0.0 0.0 13.0 10.9 dmi-c1-wg1-lu1 14.6 1.9 1.3 1.5 2.0 2.4 23.6 19.7 dmi-c3-wg1-lu2 8.9 0.4 0.2 0.1 0.2 0.2 9.9 8.3 dmi-c3-wg1-lu1 8.7 0.4 0.2 0.2 0.3 0.3 10.0 8.4 44 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. number and duration of significant water coverage appearance on the area drops drastically in both climate scenarios (fig. 4). according to the model, land use change does not have a significant effect on the water coverage, as the change of water coverage in this lu scenario is only around 0.1 percent. this can be due to the fact that groundwater levels are generally deep under the surface for all scenarios. therefore, it is not the groundwater table that is the primary reason for the occurrence of the excess water, but rather the huge amount of precipitation (or the fast snow melt) and the limited infiltration capacity of the soils (e.g. frozen soils). the effects of water governance improvement have a similarly minor effect on water coverage durations. the improved conveyance of the channels (scenario wg4) has an effect of approximately 1 percentage point on the total water coverage compared to water retention / channel storage (wg3), while no effect compared to the baseline (wg1). as expected, the no channel scenario (wg2) has a significant effect on coverage: 70% increase of total area covered, while the number of days of duration increased by 1, which can have huge implications on plant development. pilot auction exercise as it was already explained, an auction driven land-use change policy was the policy instrument that was tested with the participation of farmers from the marosszög area. by the time the exercise took place, farmers were well aware of the project, the hydrological modelling efforts as well as the upcoming efa requirements. during the exercise two scenarios were assessed: 1) individual compliance with the efa requirement, i.e. all farmers have to set aside 7% of their land for efa purposes, and discontinue traditional crop production on these parcels, 2) cooperation with each other through auction based common compliance with the 7% requirement. 20 farmers with 1702 hectares of land participated in the exercise. 7% of this area equals to 119 hectares, this is the targeted volume of land use change. farmers made bids offering (some of) their land for land use change to others at prices specified by them in eur/hectare/year. some farmers differentiated their plots based on productivity, and offered different bids for different pieces of land. altogether 55 bids were received. from the bids a supply curve was constructed, showing the price at which the cumulative quantity of land use change is offered (ungvári and kis, 2013). the constructed supply curve is monotonically increasing. the price at which 119 hectares of land conversion was offered happened to be 180 eur/hectare/year. thus, under the scheme, farmers who agreed to change their land use on behalf of others, would charge 180 eur for each hectare per year as a service to those farmers who did not want to execute the land use change on their own parcels. because of the 7% criteria, every hectare of converted land enables continued crop production on 13.3 hectares of land the 7% target implies that out of 100 hectares, 7 hectares is converted while 93 hectares stays in cultivation, thus the ratio of 93/7=13.3 results. therefore, those farmers that choose to pay others to change land use instead of them, have to pay 13.5 eur/year (180/13.3=13.5) for each hectare of their cultivated land in exchange for this service. farmers thought that these results were reasonable. assuming that the offered bids were equal to the lost profit of the corresponding land, it was estimated that if each of the 20 farmers complied with the efa requirement on their own, the lost profit would have been about 32,200 eur/year for the total cultivated area – this would have been the cost of compliance. in case the farmers cooperate with each other, the total cost declines to 20,100 eur/year – the 38% difference between the two solutions represents the economic advantage of common compliance. there are additional, unquantified changes in costs and benefits that are partly the result of land conversion, and partly driven by the auction, as the selected regulatory instrument: – the benefits of crop production are lost on the converted land, but benefits for other uses may appear (e.g. timber production). since the quality of the converted plots is below average, the profitability of crop production is probably low; for some farmers cultivating these areas may even create a loss that is balanced by the cap subisidies the only reason for farming here. thus, land use change in itself may improve the financial positions of farmers, if they continue to receive the cap subsidies while they do not any more suffer a loss on their subprime land. – the auction will enlarge these gains since it leads to the conversion of the worst 7% of the total case study area, while without this solution the worst 7% of each farm fig. 4 water coverage time series for the marosszög pilot action. effects of climate change according to the hc model ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. 45 would be converted, therefore in the latter case the average productivity of the converted land would be higher. – once land is converted, the excess water diversion channels that used to serve the converted areas can be terminated, thereby saving some of the costs of their maintenance and operation. also, less water needs to be pumped in case of a wet season when higher than normal precipitation coincides with relatively low temperatures and limited evaporation. the instrument, again, may make these gains more pronounced, since land gets converted in a more concentrated pattern – i.e. in a lower number of larger plots, rather than in a larger number of small plots –, making it more likely that some of the channels are not needed any more. as far as distributional impacts are concerned, in principle everyone is better off. the voluntary nature of the policy instrument means that there are no adverse outcomes for participants they only participate with bids that improve their position. the state can also be better off, mainly due to avoided excess water inundation related damages, which under the current regulation are partially compensated by the government. most of the land that is converted under the proposed scheme is subject to longer than average periods of excess water cover, therefore damage compensation following the land conversion can be substantially lower than today. on the other hand, the same locations may prove drought-resistant in dry years, which offers an economic advantage, but the current study does not address this issue. finally, it should be mentioned that organizing and operating the auction policy also entails costs – so called transaction costs – which should be kept low so that on balance the economic gains are not erased by the cost of implementation. relatively low administrative requirements and large size (many farmers and lots of involved land) will help to keep transaction costs low. a simplified cost benefit analysis costs and benefits were estimated and compared to determine the economic balance of the scheme. costs are associated with channel maintenance while benefits are associated with farming activities. for the analysis it was assumed that excess water cover fully destroys the crops (generally true, but not always). based on the team’s interaction with local farmers it was concluded that the profitability of crop production falls between 170 and 600 eur/hectare/year with a median value of 400 eur/hectare/year. this is how much may be lost due to too much surface water. with the help of the timavgt water management association the researchers calculated the cost of maintaining and operating the channels, separately for the larger territorial networks and the local networks consisting of narrower branches. during the calculations the frequency distribution of the inundations were also considered. the maintenance costs of the territorial network channels were estimated at 30,000 eur/year. this network, however, serves both the farms and the city of makó, thus it makes sense to share the costs in some proportion. if all eur 30,000 is to be covered by the farmers, then the benefits that they enjoy stay below this cost level, and it would not be rational to continue to maintain this network. however, if they are responsible to pay only 10% of the costs (in proportion to the diverted water that is of agricultural origin, while 90% originated from the city of makó) then a net balance of eur 24,000 results annually. therefore, under any reasonable cost allocation between the farms and the (local) government, it is worth maintaining the territorial channels, as the benefits in most years substantially exceed the costs. table 3 the annual costs and benefits of maintaining the excess water drainage networks in the model area (eur/year for the case study area, annualized) channel type benefit cost balance avoided inundation loss in the agriculture maintenance and operating cost of the channels territorial networks 27,000 30,000 / 3,000 -3,000 / 24,000 local networks 11,000 18,000 -7,000 the local branches of the network generate net costs, i.e. a loss on average. behind this average, however, there is notable deviation. there are plots with above average quality of soil that allow for vegetable production, a highly profitable activity. in these locations it generally makes sense to retain the local channels, but otherwise, most of the network is not worth maintaining. therefore, decisions on maintenance should be not uniform, but case specific. farmers are in the best position to decide if the local network segments that they use are worth maintaining at specific cost levels, or not. they will make a rational decision if they face their true share of channel maintenance and operation costs. the common compliance with the 7% efa target also helps to determine the fate of local network segments, since the parcels without valuable crop production are revealed, and these areas do not need channels. conclusion the proposed economic instrument, the auction for land use change obligation, offers a clear and direct economic advantage to the farmers with respect to complying with the ecological focus area (efa) requirement of the reformed common agricultural policy (cap). by cooperating with each other they can satisfy the cap requirements at a lower cost compared to individual compliance. once they start cooperating with each other on land use related matters, discussions of traditional agricultural practices that were abandoned during the decades of large-scale, industrialized agriculture can also take off. these discussions already started to emerge after the auction exercise, when farmers realized that the pilot scheme offers financial advantages and a more reasonable land use for the local community. the results of the hydrologic modelling show that the concentration of the ecological focus areas to the most excess water prone stretches of the landscape would 46 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. not eliminate the inundation itself. the adaptation, however, decreases agricultural damage substantially, while reducing the drainage needs, therefore providing additional economic and environmental benefits. drainage needs are also further reduced under climate change scenarios. furthermore, increased conveyance due to improved maintenance of the channels does not reduce water coverage significantly. these results, coupled with the analysis of the auction outcome suggest that some of the local branches of the water network are not worth maintaining. the territorial network channels, on the other hand, provide benefits in excess of their cost. the stable concentration of efas in the low lying areas means that efas end up in the sites with the highest potential ecological value. it also prevents the annual reallocation of efas that is allowed by the current regulation, even though this could eliminate much of the potential ecological benefits. the stable location of efas, including wetlands, ensures an increased level of ecosystem services in the form of pest control, pollination, nutrient reduction etc. the farmers endorsed the auction scheme quickly and they were satisfied with the results of the experiment. but most importantly the experimental auction process produced a credible value for the conversion as a service that they can supply to each other using their least productive land segments. a discussion took place after the presentation of the results. it showed that revealing a price information through a mechanism that is understandable and acceptable to farmers initiated a constructive dialog about the local rationality of a more sophisticated land and water management. moreover, it triggered the participants’ own calculations about the possibilities they can create for themselves. this type of thinking was not experienced earlier in this context. during the discussion they raised, for example, the question of trading between other districts for realizing further gains/cost reductions. the results also underline the importance of the eu water framework directive approach that calls for the reevaluation of the operation rationale of the water infrastructure (water services) in place and the identification of the stakeholder groups. once water users, in this case farmers, face the true cost of the services they consume, they will be able to decide if the use of these services, and thus the maintenance of the underlying infrastructure, is indeed worth for them. these decisions will also have an impact on land use, increasing the level of ecosystem services beneficial for society. lastly, an important lesson from the exercise is that entrepreneurs and enterprises are absolutely open to market based solutions, even in areas where traditionally command and control regulations are applied. acknowledgements the research resulting in this article was financed by the epi water project, under contract from the european commission grant agreement no. 265213 fp7 environment (including climate change), and took place during 2012 and 2013. the authors would like to express their gratefulness to mr. iván balla of timavgt, president of the local water management association of the marosszög at the time the research was implemented, who supported the activities through advice, information and 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(in hungarian) kozma zs., derts zs., fonyó gy., jolánkai zs., kardos m., koncsos l., muzelák b., parditka g., liska b. 2012. overview of risk based water resources scenario analysis – the waterisk decision support system. international young water professionals conference, july 10–13. 2012, budapest. kozma zs., koncsos l. 2011. methodological overview of a coupled water resources management model system. in: proceedings of the thirteenth international conference on civil, structural and http://www.eea.europa.eu/publications/cor0-landcover http://www.grida.no/publications/other/ipcc_sr/?src=/climate/ipcc/emission/ http://www.grida.no/publications/other/ipcc_sr/?src=/climate/ipcc/emission/ http://www.grida.no/publications/other/ipcc_sr/?src=/climate/ipcc/emission/ http://en.wikipedia.org/wiki/international_standard_book_number http://en.wikipedia.org/wiki/special:booksources/0-521-80081-1 http://en.wikipedia.org/wiki/special:booksources/978-052180081-5 http://en.wikipedia.org/wiki/special:booksources/0-521-80493-0 http://en.wikipedia.org/wiki/special:booksources/978-052180493-6 ungvári et al. 2018 / journal of environmental geography 11 (3–4), 37–47. 47 environmental engineering computing. b. h. v. topping, y. tsompanakis (eds.) civil-comp press, stirlingshire, uk, paper 157. doi:10.4203/ccp.96.157. kozma, zs., ács, t., koncsos, l. 2014. unsaturated zone modelling – the role of soil database classification, in: c a brebbia, h bjornlund (ed.) sustainable irrigation and drainage v. 280 p. southampton: witpress, 2014. pp. 197-210. wit transactions on ecology and the environment; 185. isbn:978-1-84564-788-9 kozma, zs., koncsos, l., jolánkai, zs., kardos, m., koncsos, t., muzelák, b., parditka, g., liska, b., derts, zs., 2012. overview of risk based water resources scenario analysis – the waterisk decision support system. proceedings of the 6th iwa international conference for young water professionals, budapest, hungary, (cd id: iwa-9847) maziotis, a., l. carrera, f. farinosi, j. mysiak. 2012. output no. 7. in epi-water wp4: policy relevance of the epis from an european perspective. millennium ecosystem assessment (mea) 2005. ecosystems and human well-being: synthesis, island press, washington dc. available at: http://www.maweb.org/en/synthesis.aspx molnár, zs., deák, j. á. 2013. ‘a makói mintaterület természetföldrajzi és tájtörténeti értékelése.’ (the geography and landscape history of the makó pilot area.), background document for epi-water. moriasi, d. n., arnold, j. g., van liew, m. w., bingner, r. l., harmel, r. d., veith, t. l., 2007. model evaluation guidelines for systematic quantification of accuracy in watershed simulations. transactions of the asabe, 50, 885–900. doi: 10.13031/2013.23153 müller, klaus, h-p. weikard. 2002. ‚auction mechanisms for soil and habitat protection programmes.’ in hagedorn, konrad (ed.), environmental co-operation and institutional change., cheltenham: edward elgar, 202–213. mysiak, j., h. j. henrikson, c. sullivan, j. bromley and c. pahl-wostl. 2010. the adaptive water resource management handbook. earthscan, uk and usa. omsz (national weathr service): data series on climate, link: http://owww.met.hu/eghajlat/eghajlati_adatsorok/sz/navig/204e. htm ovf országos vízügyi főigazgatóság. 2016. a duna vízgyűjtő magyarországi része, vízgyűjtő-gazdálkodási terv 2015. [the hungarian part of the danube river basin, water management plan 2015] pásztor, l., kőrösparti, j., bozán, cs., laborczi, a., takács, k. 2015. spatial risk assessment of hydrological extremities: inland excess water hazard, szabolcs-szatmár-bereg county, hungary. journal of maps 11(4), 636–644. doi: 10.1080/17445647.2014.954647 pásztor, l., laborczi, a., takács, k., szatmári, g., bakacsi, z., szabó, j., illés, g. 2018. dosoremi as the national implementation of globalsoilmap for the territory of hungary, in proceedings of the global soil map 2017 conference, july 4-6, 2017, edited by arrouay d., savin i., leenaars j., mcbratney a. b., crc press, moscow, russia, pp. 17–22. pinke, zs., kiss, m., lövei, g. l. 2018. developing an integrated land use planning system on reclaimed wetlands of the hungarian plain using economic valuation of ecosystem services, ecosystem services 30(b), 299–308. doi: 10.1016/j.ecoser.2017.09.007 spanoudaki, k., stamou, a. i., nanou-giannarou, a. 2009. development and verification of a 3-d integrated surface watergroundwater model, journal of hydrology 375(3-4), 410–427. doi: 10.1016/j.jhydrol.2009.06.041 ungvári, g and kis, a. (lead authors). 2013. epi-water deliverable no. d.4-2 report of the case study task 4.1: wp4 ex-ante case studies. floods and water logging in the tisza river basin (hungary). szatmári, j., van leeuwen, b (ed.), 203. inland excess water belvíz suvišne unutrašnje vode szeged; újvidék: szegedi tudományegyetem; újvidéki egyetem, 154 p. van leeuwen, b., právetz, t., liptay, z. á., tobak, z. 2016. physically based hydrological modelling of inland excess water. carpathian journal of earth and environmental sciences 11(2), 497–510. van leeuwen, b., tobak, z., szatmári, j. 2008. development of an integrated ann-gis framework for inland excess water monitoring. journal of env. geogr. 1(3-4), 1–6. doi: 10.2478/v10326-012-0001-5 viaggi, d. and m. vollaro. 2012. output no. 5. in epi-water wp 4.1: input on agricultural themes: environmental performance of the cap schemes and the new conditions of the cap schemes that will operate in the next eu budget. vituki, 1972. éves beszámoló. a duna-medence magyarországi részének vízmérlege.ismerteti: kardos mária. (annual report: the water budget of the hungarian part of the danube basin, reported by maria kardos) vtosz vízgazdálkodási társulatok országos szövetsége, 2011. tájékoztató a területi vízgazdálkodási társulatok feladatairól és lehetőségeiről napjainkban. tájékoztató az országgyűlés fenntartható fejlődés bizottságának 2011. február 3-i ülésére. [information on the tasks and options of the regional water management associations. prepared for the 3 february 2011 gathering of the national council for sustainable development of the parliament] weikard, h-p., zetland, d., ayres, a., and lago, m. august, 2012. output no. 6. in epi-water wp 4.1 auction mechanisms for water management http://www.maweb.org/en/synthesis.aspx introduction study area methods the methodological concept applied instruments – hydrological simulation scenario development applied instruments economic exercise results hydrological model calibration hydrological simulations pilot auction exercise a simplified cost benefit analysis conclusion acknowledgements references journal of environmental geography journal of environmental geography 7 (1–2), 11–22. doi: 10.2478/jengeo-2014-0002 issn: 2060-467x dataset for creating pedotransfer functions to estimate organic liquid retention of soils hilda hernádi * , andrás makó department of crop production and soil science, georgikon faculty, university of pannonia, deák f. u. 16, h-8360 keszthely, hungary *corresponding author, e-mail: hhilduci@gmail.com research article, received 27 january 2014, accepted 14 march 2014 abstract soil properties characterising pressure-saturation relationships (p-s), such as the fluid retention values or the fitting paramete r of retention curves are basic input parameters for simulating the behaviour and transport of nonaqueous phase liquids (napls) in subsurface. recent investigations have shown the limited applicability of the commonly used estimation methods for predicting napl retention values in environmental practice. alternatively, building pedotransfer functions (ptfs) based on the easily measurable properties of soils might give more accurate and reliable results for estimating hydraulic propertie s of soils and enable the utilisation of the wide range of data incorporated in hungarian and international datasets. in spite of the availability of several well-established ptfs to predict the water retention of soils only a limited amount of research has been done concerning the napl retention of soils. thus, in our study, data from our recent napl and water retention mea surements were collected into a dataset containing the basic soil properties as well. relationships between basic soil propert ies and fluid retention of soils with water or an organic liquid (dun asol 180/220) were investigated with principal component analysis. napl retention of soil samples were determined with ptfs, based on basic soil properties and their d erived values, and using a scaling method. result of the statistical analysis (spss 13.1) revealed that using ptfs could be a promising alte rnative and could give more accurate results compared to the scaling method both for determining the napl saturation or the volumetric napl retention values of soils. keywords: napl retention, pedotransfer function, hydraulic characteristics, leverett equation introduction from the 1980s increased attention has been received to improve understanding the relevant characteri stics and processes in flow and transport of s ubsurface nonaqueous phase liquids (napl) firstly in petrol industry and later to help design remedial strategies. knowledge of pressure-saturation (p-s) relationships is essential for simulating the fate and transport of nonaqueous phase liquids (napls) in subsurface with any type of models. nowadays, as the measur ements of hydraulic parameters are costly and time consuming the development of accurate estimation method is preferred. in environmental practice the napl retention of soils is commonly determined by the table of average empirical pressure-saturation (p-s) values (depastrovitch et al., 1979), table of average fitting parameters of the van genuchten equations proposed by ca rsel and parrish (1988) (e.g. in retz model – van genuchten et al., 1991; hssm model – weawer et al., 1994), the different modified versions of the leverett function (leverett, 1941) or their combination. in addition, beckett and joy (2003) created a dataset of calculated fitting parameters based on the modified scaling method suggested by lenhard and parker (1987). nevertheless, tables of average napl rete ntion or fitting parameter values of fluid retention curves do not accurately represent the variability of soils with different physical and chemical properties. all type of the modified leverett function is valid for ideal porous systems. these estimation methods do not take into account the different interactions b etween the various fluids and the porous media, thus their application might be limited for natural soils (i.e. well aggregated, higher organic matter or clay co ntent, etc.) soils. furthermore, they have not been properly validated (only a few methods validated with column experiments, but these were carried out in most cases with glass beads and/or sands) (rathfelder and abriola, 1996; makó and hernádi, 2013). in the commonly used fluid retention measurement methods usually only the main drainage curves are measured. the more accurate determination of the main drainage curve of soil has key importance in determining the transport parameters (e.g. residual organic liquid content, penetration depth and time). in addition, main drainage curves could be the basis of determining the hysteretic and scanning curves in hysteretic models. 12 hernádi and makó (2014) predicting of the physical, chemical and biological properties of soils with pedotransfer functions (ptfs) is a fast-developing field and several well-established ptfs are available to predict the water retention of soils both in hungary (rajkai, 2004; rajkai et al., 1996; 2004; nemes, 2003; makó et al., 2005 and tóth, 2011) and abroad (minasny et al., 1999; wösten et al., 1999; rawls et al., 2001, etc.). most of these estimation methods have already been incorporated into numerical algorithms such as soilpar 2.0 (acutis and donatelli, 2003), neuro multistep (minasny et al., 2004), talajtanonc 1.0 (fodor and rajkai, 2011) or the k-nearest (nemes et al., 2008), etc. however, only a few studies had begun focusing on creating ptfs concerning the soils organic liquid retention capacity. experiences in creating ptfs for water retentions may be essential tool for obtain the best possible estimation method for predicting the napl retention. ptfs for water retention (as response variable) may be created for the measured point values of the pressure saturation curves (point estimation) or for the fitting parameters of the hydraulic functions (parameter estimation) (brooks and corey, 1964; brutsaert, 1966; van genuchten, 1980) based on the easily measurable basic soil properties or their derived values (predictor variables) (wösten, 1995). the parameter estimation methods are widely used in environmental and soil hydrological practices because the simulation models mainly use these fitting parameters as input variable. moreover, these parameters are equal to those of the equations predicting the soil hydraulic conductivity and relative permeability (van genuchten, 1980; lenhard and parker, 1987; chen et al., 1999). if the results of two point ptfs were to be compared or if no measured water rete ntion points are available for a particular ptf, (or vice versa) the comparison of the retention curves with using the fitted hydraulic parameters (minasny et al., 1999; rawls et al., 2001) or calculating the estimated water contents at the desired pressure heads by l inear interpolation were suggested (tietje and tapkenhi nrichs 1993; schaap and leij, 2001). for parametric methods it is common to predict logarithmic transformed values of α (ln α) and n (ln n 1) to convert the distribution of the parameters into a more statistically normal distribution (e.g., rawls and brakensiek, 1985; wösten et al, 1999). both in case of water and napl retention estimation, application of similar soil properties (bulk density or texture class information, organic matter and carbonate co ntent, etc.) or their inherited values (e.g. the averaged values of particle size data) were suggested as independent variables (makó, 2004; makó and elek, 2006). in case of predicting the water retention the texture, morphology etc. are commonly used as a grouping factor in developing ptfs (wösten et al. 1995; schaap et al. 1999, 2001; pachepsky and rawls 2004). statistical attributes of comparing ptfs for predicting water retention can potentially be adapted for the investigation of napl retention estimation methods. recently, the determination of accuracy (with the working dataset), uncertainty and reliability (with test data) of the predictions, r, r2, mean error (me), mean square error (mse), root mean square error (rmse), the unbiased root mean square errors (urmse), etc. and their complete calculation are recommended, to acchieve a comprehensive verific ation (pachepsky and rawls, 2004). for the comparison of the accuracy of the fitted fluid retention curves the calculation of zapf values were suggested by rajkai (2004). the aic (akaike information criter ion) value offers the possibility to compare the efficiency of different estimation or fitting methods with various numbers of parameters and the models with lower error can be selected with fisher’s test (rajkai, 2004). the uncertainty in input data can be evaluated using monte carlo analysis (minasny et al. 1999), procedures based on fuzzy rules (mcbratney et al., 2002) or with the bootstrap method (carsel and parish, 1988). nowadays, the development of inference systems (e.g. sinfer) to select the proper ptfs with minimum variance based on logical rules (mcbra tney et al., 2002)., or the application of data driven methods, e.g. support vector machines (lamorsky et al., 2008) might be a challenging t opic. the stability of the estimated coefficients can be i nvestigated using the double cross-validation techniques (k-fold, leave-one-out, jackknife or delete-d methods) with randomly split the data (pachepsky and rawls, 2004). according to tóth et al., (2013) it may be sufficient to random spilt the data in proportion of 90:10 (working and test data). besides, many authors suggested the detection of outliers for calibrating ptfs. to our current knowledge, there is only one research had begun for creating ptfs concerning the soils organic liquid retention in europe (makó, 1995; makó, 2002; 2004). in spite of the large number of measurements to determine the napl rete ntion of soils, databases from measured napl rete ntion data have not been created until now. beckett and joy (2003) created a dataset of calculated fitting param eters based on the modified scaling met hod suggested by lenhard and parker (1987) and parker et al. (1987) but this contains the scaled napl retention values calculated from the fitted water retention values of hypres database. creating ptfs for napl-retention might be promising because a large amount of measured basic data is available in national and hungarian databases (hypres, uns oda v2.0, hunsoda, eu hydi, martha etc.), which have already been used effectively in developing ptfs for estimating water retention (wösten et al., 1995; nemes et al., 2003, 2008; makó et al., 2005; tóth et al., 2006, 2013; lilly, 2010). more over, the up-to-date hydrodynamic and transport mo dels enable the adaptation of gis (geographic information systems) datasets (e.g. gms groundwater modelling system and argus open numerical env ironments argus one), which allow for cartographic representation with different commonly used software applications in the environmental engineer dataset for creating pedotransfer functions to estimate organic liquid retention of soils 13 ing practice (such us surfer-grapher or autocad). in the 1990s a series of investigations for measuring napl retention of soils and mineral mi xtures with the pressure plate method to create ptfs for organic liquid retention, in hu ngary were started (makó, 1995; makó, 2002). in this study a dataset from these recent mea surements was created and analysed by statistical methods (spss 13.1). after the preliminary analysis (descriptive statistics and outlier detections), ptfs were built for predicting the fitting parameters of napl retention curves. then, the napl retention of soils was predicted with classptfs (for selected four texture groups) and using the scaling method of le nhard and parker (1987). afterwards, the accuracy and reliability of predicting napl retention with different estimation methods were compared. description of the dataset the dataset contains the physical and chemical pro perties and the fluid retention data of five measurement series collected from 1991 to 2011 (table 1-2). dataset contains 369 disturbed and undisturbed samples, 40 soil profiles with 107 genetic layers and various types of soils (fig. 1) for 10 texture classes are represented (fig. 2). table 1 the subsets of dataset subset n % origin 1 111 30.1 undisturbed samples of 9 soil profiles of the research program of the hungarian national long-term fertilization (hernádi and makó, 2011a) 2 123 33.3 undisturbed samples of 12 soil profiles of an investigation for the hungarian gas & oil company plc (mol rt.) (makó, 2002; 2005) 3 45 12.2 disturbed samples of mineral mixture series (hernádi et al., 2011b) (makó and marczali, 1999) 4 60 16.3 disturbed samples of aggregate series separated from the upper „a” layer of selected soils (2.0 mm>, 1.0 mm>, 0,5 mm>, 0,25 mm> and 0,056 mm>) (makó and elek, 2006) 5* 30 8.1 disturbed samples investigated in the course of the támop-4.2.1/b09/1/konv-2010-0003 mobility and environment project (hernádi et al., 2011) sum 369 100 * before fluid retention measurements, samples were held 24hr in water for desaggregation and dried on 40°c/24hr table 2 soil properties in the dataset n n% water retention napl retention vol.% n n% vol.% n n% surface area (bet) (cm 2 g -1 ) (brunaer et al., 1938) 144 39.0 pf 0.0 308 83.5 0 mbar 245 66.4 plasticity according to arany (%) (buzás, 1993) 339 91.9 pf 0.2 170 46.1 2 mbar 361 97.9 particle size distribution (%)* 312 84.6 pf 1.0 111 30.1 20 mbar 242 65.6 particle size distribution (%) ** 369 100.0 pf 1.3 59 16.0 50 mbar 245 66.4 organic matter content (%) *** 369 100.0 pf 1.5 279 75.6 100 mbar 116 31.4 caco3 (%)*** 369 100.0 pf 1.7 59 16.0 150 mbar 245 66.4 acidity (na4oac) (cmol (+) kg -1 )*** 66 17.9 pf 2.0 156 42.3 200 mbar 116 31.4 acidity (kcl) (cmol (+) kg -1 )*** 66 17.9 pf 2.2 59 16.0 400 mbar 245 66.4 salt content (mass %)*** 93 25.2 pf 2.3 111 30.1 500 mbar 116 31.4 exchangeable na (cmol(+)/kg)*** 87 23.6 pf 2.5 168 45.5 1000 mbar 361 97.8 base saturation (w %)*** 24 6.5 pf 2.6 59 16.0 1500 mbar 30 8.1 aggregate size distribution (%)* 105 28.5 pf 2.7 111 30.1 ph (distilled water 1 : 2,5)*** 273 74.0 pf 3.0 59 16.0 ph (kcl suspension 1 : 2,5)*** 189 51.2 pf 3.2 30 8.1 bulk density (water) (g cm -3 )* 348 94.3 pf 3.4 111 30.1 bulk density (napl) (g cm -3 )* 369 100.0 pf 4.2 279 75.6 pf 6.2 369 100.0 * physical properties of soils were determined according to msz 08 0205:1978 standard (psd – pipette method) **psd of soils is determined according to iso 11277:1995 with pipette method, after the total desaggregation of soil samples (eliminating the soil organic matter and caco3 content and the iron oxides). ***chemical properties of soils were determined according to msz 08 0206/2:1978 standard 14 hernádi and makó (2014) methods the basic soil properties, used in this investigation were measured according to the hungarian standards (msz08 0205:1978 and msz08 0206/2:1978). the texture of soil samples was determined according to the isss (international society of soil science) texture triangle (table 3). the fluid retention measurements were performed with distilled water and a special nonaromatic organic liquid, dunasol 180/220 (hungarian gas & oil company plc. mol rt.). water retention measurements were carried out with porous pressure plate extractors (soilmoisture corp. lab 023). for the purpose of determining the napl retention of the samples, a modified version (as described by makó, 1995) of these pressure plate extractors were used. samples showing extremely high or low napl retention values were selected with outlier detection. only the samples, were the casewise diagnostic of the preliminary linear regression between soil parameters and fluid retention values showed significant differences with more than two times the standard deviation at a given pressure level, were eliminated. then only the records where both the water and napl retention were measured were retained. therefore, the final dataset contained 316 samples. the fluid retention measurements were performed with distilled water and a special nonaromatic organic liquid, dunasol 180/220 (hungarian gas & oil company plc. mol rt.). water retention measurements were carried out with porous pressure plate extractors (soilmoisture corp. lab 023). for the purpose of determining the napl retention of the samples, a modified version (as described by makó, 1995) of these pressure plate extractors were used. fig. 1 wrb (world reference base) soil types, clay minerals and mineral mixtures in the dataset (1: benite, 2: kaolin, 3: illite, 4: loess, 5: pannon sand, 6: mineral mixtures, 10: eutric cambisol, 11: hortic terric cambisol, 12: dystric cambisol, 20: haplic arenosol, 30: gleyic luvisol, 40: calcic phaeosem, 41: luvic phaeozem, 42: calcaric phaeozem, 43: haplic phaeozem, 50: vermic calcic chernozem, 60: vertic stagnic solonetz, 61: orthic solonetz, 70: gleyic vertisol, 80: calcaric gleysol, 90: eutric regosol, 100: calcaric fluvisol) fig.2 texture and sample types of soil, clay minerals and mineral mixture samples (1: clay, 2: silty clay, 4:clay loam, 5: silty clay loam, 6: sandy clay loam, 7: loam, 8: silt loam, 9: sandy loam, 11:loamy sand, 12: sand; a: disturbed samples, b: undisturbed samples, c: mineral mixtures, d: aggregate series of soil samples) dataset for creating pedotransfer functions to estimate organic liquid retention of soils 15 samples showing extremely high or low napl r etention values were selected with outlier detection. only the samples, were the casewise diagnostic of the preliminary linear regression between soil parameters and fluid retention values showed significant diffe rences with more than two times the standard deviation at a given pressure level, were eliminated. then only the records where both the water and napl retentio n were measured were retained. therefore, the final dataset contained 316 samples. for fitting the napl retention curves the van genuchten equation with three parameters (eq. 1) (van genuchten et al., 1980) were used as initial values in nonlinear regression (spss 13.1, nonlinear regression/quadratic sequential programming) with the average fitting parameters proposed by carsel and parish (1988) (used in e.g. retz and hssm models).    nn s h h 1 1 )( 1       (1) where: θ(h) is the volumetric fluid content at potential h (kpa); θs,is the saturated fluid content; α, and n are fitting parameters. afterwards, napl retention values for 10 pressure levels (0.01, 0.3, 10, 33, 100, 200, 330, 1000, 15849 and 1584893 mbar) were calculated. the accuracy of fitting was verified by the calculation of pearson r 2 , rmse (eq. 2) and zapf values (eq. 3) (rajkai, 2004). n yy rmse n ii   1 2 )ˆ( (2) where: yi is the fitted napl retention, ŷi the estimated napl retention and n is the number of samples. in case of zapf values (eq. 3.), the lower |zapf| than measurement error (me) of napl retention was regarded as sufficiently fitted (as suggested by rajkai, 2004). n zapf n i me    1  (3) where: θm is the measured fluid retention value θe estimated fluid retention values; n is the number of fitting point of fluid retention curves. before creating ptfs the dataset was randomly split with the ratio of 90:10 (calibration and validation data set), thus we had opportunity to investigate the accuracy and the also the reliability of estimations (table 4). in further investigations the fitted fluid retention data was used, which enabled us to compare the retention data determined with both fluid types measured at different pressure levels. relationships between basic soil properties and fluid retentions, as well as between soil properties and fitting parameters were preliminarily investigated with principal comp onent analysis (pca) (spss 13.1/varimax rotation with kaiser normalization). subsequently, parametric ptfs were built as class ptfs for selected four texture groups (silty clay, silty clay loam, silt loam and sandy loam) with multiple linear regression (spss 13.1 linear regression/stepwise method). in linear regression, bulk density, clay, silt, caco3 and organic matter content and their derived values, such as the logarithmic, reciprocal, squared values and their interactions were used as independent variables (as suggested by wösten, 1995). the napl retention of the soil samples were pr edicted with a modified fitting method proposed by lenhard and parker (1987) (eq. 4) which was a co mbination of the leverett equation (1941) and a four parametric fitting procedure suggested by van genuchten et al. (1980).   m n p s         1 1 (4) where: s is the fluid saturation; p is the pressure head; β is a scaling factor calculated from the interfacial tension of the phase pair and α, n and m are fitting parameters. in scaling method the m = 1-1/n constraints was supposed as suggested by van genuchten (1991). in order to compare the accuracy and reliability of the different predictions, the rmse and r 2 values were determined. the napl saturation values of soil samples were also calculated on the validation test in order to make a preliminary investigation to compare the reliability of ptfs with scaling method in predicting napl saturation values, versus the pressure. table 3 descriptive statistics of the selected basic soil properties used in this study method unit mean sd se med. min. max. n clay msz 08 0205:1978 w % 27.58 0.95 16.75 24.08 1.25 67.67 369 silt 44.22 0.91 16.11 44.39 0.05 78.50 369 sand 28.21 1.43 25.20 21.43 0.63 98.62 369 om msz 08 0206/2:1978 w % 1.43 0.06 1.24 1.21 0.00 5.66 369 caco3 msz 08 0206/2:1978 w % 5.57 0.43 8.26 0.16 0.00 30.71 369 bulk density (water)* msz 08 0205:1978 g cm -3 1.43 0.01 0.19 1.44 0.89 2.20 369 bulk density* (napl) msz 08 0205:1978 g cm -3 1.42 0.01 0.26 1.45 0.80 1.99 369 *samples for water and napl retention measurements had different bulk density. 16 hernádi and makó (2014) results and discussion fitting van genuchten equation as the determination coefficient showed napl rete ntion curves can be accurately fitted with the hydraulic function proposed by van genuchten (1980). moreover, according to the zapf values, the differences between the fitted and measured napl retention va lues were lower than the measurement error in more than 98.4% of the samples (table 5). table 5 statistics of the fitted van genucthen equation to the measured napl retention values equation zapf (<0,75 – me*) rmse r r 2 n frequency (%) van genuchten (3 parameter) 2286.0 98.4 1.2 0.99 0.99 * me is the average error of napl retention measurement principal component analysis principal components were extracted from 17 variables which showed strong correlations between the selected soil properties. the maximum possible variance of 90.92% can be explained by the three components. scores of component i (ci) give information about 69.56% scores of component ii (cii) about 15.48% and scores of component iii (ciii) about 5.87% of the variance of variables. after kaiser normalization, all components with eigenvalues under 1.0 were eliminated, and only three components were taken into account. in table 6 and 7, component scores less than the variance explained criteria (0.4) are shown in gray. communality values show, that all the variances of each correlated vari ables might be accounted for by the co mponents. the finer textured fractions belonged to the same comp onent with the napl retention at higher pressure levels, where the organic liquid can be retained against gravity mainly by capillary and adsorptive forces. the joint variation of these soil properties were a ffected by ci as the unobserved latent variable. mor eover, the component scores of finer particle size fractions exceeded the 0.4 criteria only in ci. differences in the role of components on the napl retention of soils were observed. increasing value of component scores with increasing pressure can refer to the strong correlations between particle size distribution and fluid retention, especially in the higher pressure range. higher component scores of cii were observed than ci on the 0-50mbar pressure range. in cii only the fluid retention less than 150 mbar were represented while the component scores of ci in case of napl retention at table 4 statistics of the fitted fluid retention values in calibration and validation datasets pressure (mbar) calibration set validation set n = 264 n = 26 mean se sd med. min. max. mean se sd med. min. max. napl retention 0.0 41.0 1.0 10.0 41.0 22.0 68.0 38.0 2.0 10.0 37.0 25.0 57.0 0.33 41.0 1.0 10.0 41.0 22.0 68.0 38.0 2.0 10.0 36.0 25.0 57.0 10 36.0 1.0 10.0 35.0 17.0 64.0 33.0 2.0 8.0 32.0 21.0 49.0 33 31.0 1.0 8.0 31.0 9.0 62.0 28.0 1.0 5.0 29.0 20.0 38.0 100 25.0 0.0 6.0 25.0 5.0 60.0 24.0 1.0 5.0 24.0 16.0 33.0 200 22.0 0.0 6.0 21.0 3.0 55.0 22.0 1.0 6.0 22.0 10.0 32.0 330 20.0 0.0 6.0 19.0 2.0 49.0 21.0 1.0 6.0 22.0 7.0 32.0 1000 17.0 0.0 6.0 16.0 1.0 34.0 18.0 1.0 7.0 18.0 3.0 30.0 15849 11.0 0.0 7.0 11.0 0.0 29.0 14.0 1.0 7.0 14.0 0.0 26.0 1584893 7.0 0.0 6.0 6.0 0.0 22.0 10.0 1.0 6.0 9.0 0.0 21.0 water retention 0.0 50.0 1.0 11.0 47.0 27.0 81.0 49.0 2.0 9.0 47.0 37.0 70.0 0.33 50.0 1.0 11.0 47.0 26.0 81.0 49.0 2.0 9.0 47.0 37.0 70.0 10 48.0 1.0 11.0 46.0 16.0 78.0 47.0 2.0 9.0 46.0 36.0 69.0 33 45.0 1.0 11.0 43.0 12.0 73.0 45.0 2.0 10.0 42.0 31.0 67.0 100 41.0 1.0 12.0 39.0 5.0 73.0 42.0 2.0 10.0 40.0 26.0 63.0 200 37.0 1.0 12.0 36.0 1.0 72.0 39.0 2.0 10.0 39.0 23.0 62.0 330 35.0 1.0 12.0 33.0 0.0 70.0 37.0 2.0 10.0 38.0 21.0 61.0 1000 29.0 1.0 11.0 27.0 0.0 65.0 32.0 2.0 10.0 32.0 17.0 56.0 15849 17.0 0.0 8.0 16.0 0.0 41.0 19.0 1.0 7.0 19.0 7.0 37.0 1584893 7.0 0.0 4.0 6.0 0.0 19.0 8.0 1.0 3.0 8.0 1.0 15.0 dataset for creating pedotransfer functions to estimate organic liquid retention of soils 17 higher than 400 mbar exceed the 0.9 value (table 6.) this difference might be resulted from reaching a threshold pressure range, which can be in the range of 20-50 mbar. at this pressure range the larger pores might be drained by gravity during napl retention measurements with dunasol 180/220, as similar results were observed by makó et al. (2011a). this is lower than the pressure of the field capacity of soils, which is referred approximately 400 mbar (pf 2.5) in the case of water retention. this is might not be contradicted to the results of other researchers for water retention (vere ecken et al., 1989; saxton and rawls, 2006). vereecken et al., (1989) resulted that at pressure higher than 1500 kpa water retention is determined mainly by texture then in lower pressure range the fluid retention strongly influenced by the aggregation of soil particles and organic matter content as well. however, in case of napl retention the variance of organic matter content affects the napl retention but in decreasing rate with increasing pressure in ci and cii, and calcium carbonate content of samples appeared only in ciii. variance in bulk densities can be explained by all three components, thus it may influence the napl retention at every pressure level. in all cases bulk density had negative correlation with other variables which refers inverse relationships between bulk dens ity and fluid content of soils samples. more complex and less correlation between parameters of water and napl retention curves related to basic soil properties were observed. in case of water retention only the 55.59% of the variance could be explained by the components as compared to napl retention (76.55% (table 7). parameters α, n and θs have substantial roles in ci of napl retention in contrast to the parameters of water retention curves which belong to separated principal components. descriptive statistics show (table 4), that the mean saturated water content is significantly higher (50 vol %) than the possible average maximum napl retention (41 vol %), which might influence the variability of the other two fitting parameters. parameters α and n are shape factors, strongly influenced by the pore size distribution of soils and structure (van genuchten et al., 1991; vereecken et al., 1989). however, there is a difference in effective pore size distribution of soils saturated by fluids with various chemical and physical properties. in addition, interactions between water and the solid phase during drainage and imbibition processes, such as swelling and shrinking, have not occurred in case of the soil pores filled with napls. thus, the soil properties which might influence the shape of fluid retention curves might be difference. strong correlation between the fitting parameters was experienced when the van genuchten equation was fitted to napl retention data. the correlation between α and θs of the selected four texture group varied between 0.553-0.887. this might refers the inability of using the same initial parameters or boundary conditions for fitting napl and water retention curves. lower communality values were experienced in the n and θs values of water retention curves than those of napl retention curves. this could be resulted from the variability in napl retention of soils might be explained better with the selected basic soil properties (communalities of n was 0.821, and θs was 0.739) than in case of water retention (where the c umulated variance was only 0.282 and 0.298). table 6 components of variance and scores of the principal component analysis variables ci cii ciii communalities basic soil properties 0.0002 mm > 0.93 0.22 -0.19 0.94 0.005-0.002 mm 0.87 0.36 0.11 0.89 0.01-0.005 mm 0.91 0.30 0.18 0.94 0.02-0.01 mm 0.75 0.35 0.50 0.93 0.05-0.02 mm 0.02 0.41 0.88 0.95 0.05-0.25 mm -0.94 0.05 -0.33 0.99 organic matter (w %) 0.56 0.46 0.02 0.53 caco3 (w %) -0.07 0.05 0.95 0.91 bulk density (g cm -3 ) -0.51 -0.53 -0.53 0.82 napl retention 0mbar (w %) 0.48 0.66 0.46 0.88 2mbar (w%) 0.49 0.65 0.45 0.87 20mbar (w %) 0.46 0.76 0.39 0.94 50mbar (w %) 0.56 0.59 0.54 0.96 150mbar (w %) 0.78 0.46 0.40 0.98 400mbar (w %) 0.91 0.34 0.14 0.96 1000mbar (w %) 0.93 0.34 0.04 0.98 1500mbar (w %) 0.90 0.41 -0.05 0.98 statistics variance % 69.56 15.48 5.87 18 hernádi and makó (2014) in both cases bulk density is presented in ci with negative effect on saturated fluid content, which can be a consequence the bulk density and saturated fluid content are closely related. in case of water retention the role of organic matter content is apparent only in ciii separately from clay content. this can be a consequence of the effect of high clay content might mask the effects of increasing organic matter for water retention, as saxton and rawls (2006) and rawls et al. (2003) experienced as well. similar relationships observed between organic matter content and the fitting parameters of water retention curves than petersen et al. (1968) and vereeckeen et al. (1989) that is the organic matter co ntent of soils affects primary the α parameter of water retention curves, which refers the fluid rete ntion values at inflection point. in contrary with texture, organic matter content of soils influence the position of the retention curves, rather than its shape. communality values showed the same important role of calcium carbonate (0.722, 0.709) and organic matter (0.579, 0.454) on water and napl retention. however, a separated component (ciii) was composed by organic matter, caco 3 and clay content in case of napl retention data. in addition the role of clay content on water retention seemed to be higher than its role on napl retention. all of these o bserved relationships refer to the different rate of interactions between various fluids and the solid phase considering these express mainly the linear relationships between these variables. in spite of the cumulated variance was only 55.59 % in case of water retention, the kaiser -meyer-olkin test showed the applicability of pca, sampling ad equacy (as it refers that the correlations between pairs of variables can be explained with other variables) was higher than 0.5, and the barthlett’s test indicated significant correlation between variables (p<0.05). pedotransfer functions accurate prediction was given by classptfs for the selected four texture groups for estimating napl retention of soils (table 8). table 8 accuracy of ptfs to estimate fitting parameters of napl retention curves parameter r 2 rmse α 0.978 13.59 n 0.900 17.75 θs 0.988 7.50 according to the rmse values classptfs give more accurate estimations to saturated fluid co ntent than the shape parameters α or n. the lower efficiency of estimating parameter α might be caused by the strong correlations experienced b etween parameters α and θs and might also resulted from the weaker correlation with independent variables. table 7 components of variance and scores of the principal component analysis with parameters of fluid retention curves variables water retention napl retention 4 ci cii ciii communalities ci cii ciii communalities a 0.025 -0.072 0.753 0.665 -0.738 0.451 -0.041 0.749 n -0.155 0.581 -0.101 0.282 0.468 -0.775 0.021 0.821 θs -0.602 0.171 -0.228 0.298 0.841 0.155 0.085 0.739 clay content (w %) 0.847 -0.163 -0.237 0.933 0.409 0.657 -0.455 0.806 silt content (w %) 0.469 0.478 0.077 0.932 0.097 0.815 0.337 0.788 organic matter (w %) 0.014 0.123 0.784 0.579 -0.187 0.074 0.643 0.454 caco3 (w %) 0.084 0.801 0.137 0.722 0.426 0.03 0.726 0.709 bulk density (g cm -3 ) -0.638 -0.315 -0.034 0.686 -0.889 0.016 0.136 0.808 variance % 22.768 17.792 22.768 33.191 29.179 14.184 cumulated variance % 22.768 40.560 55.599 33.191 62.370 76.554 bartlett's test of sphericity 0.000 0.000 kaiser-meyer-olkin measure of sampling adequacy 0.597 0.634 dataset for creating pedotransfer functions to estimate organic liquid retention of soils 19 the applicability of ptfs to predict the napl retention values was proven by the statistical attributes (r 2 and rmse). in comparison the accuracy of parametric ptfs with the scaling method, napl retention might be better predicted with ptfs at a given pressure level (fig. 3). applicability of these estimation methods for predicting napl saturation values of soils was compared with the determination of r 2 and rmse values on validation data (10 % of the dataset, 26 samples). lower reliability of ptfs was found to estimate the napl saturation with ptfs than the scaling method at higher than 100 mbar pressure level. however, ptfs could provide estimates sufficiently reliable for napl retention at all pressure level, especially near saturation (fig. 4). on fig. 4 the statistics of saturated fluid content were not presented because their values are 1 for both fluids. supposedly, scaling method gave increasing better estimation for napl retention as a consequence of decreasing difference between fluid retentions with napl and water. as it shown formerly from descriptive statistics (table 4), the difference between the average water and napl retention of the investigated soil samples was 26 vol. % at 100 mbar but practically 0 vol. % at 1584893 mbar. at the same time rmse values indicated lower difference in reliability of estimation methods for predicting the napl saturation. only moderate reliability of ptfs was found when predicting the volumetric napl retention values (fig. 5). in spite of the fact that higher rmse values were observed for ptfs in lower pressure ranges, the r 2 values show that the reliability of ptfs exceed that of the scaling method at lower pressure levels (< 330 mbar) and is al fig. 3 accuracy of estimating volumetric napl retention values with different estimation methods par: the parametric method based on basic soil properties and their derived values; sc: scaling method (lenhard and parker, 1987) fig. 4 reliability of estimating napl saturation values with ptf and scaling methods par: the parametric method based on basic soil properties and their derived values; sc: scaling method (lenhard and parker, 1987) 20 hernádi and makó (2014) most equal to it at pressure higher than 1000 mbar (fig. 5). moreover both the decreasing r 2 values of the scaling method and the increasing rmse values in the midpressure range (near the inflection point of the napl retention curves) suggest the inability of scaling methods for predicting napl retention of soil based on water retention. conclusion in the last fifteen years several investigations were performed in order to create estimation methods to predict the napl retention of soils. however, the results of these measurements have not been collected into comprehensive and well established databases, yet. building ptfs using the data of easily measured soil property data might be a promising alternative for predicting the napl retention of soils. by the creation of an organic liquid retention database representative for most soil types we can generate well established point and parametric ptfs based on basic soil properties. after the validation of ptfs with the results of column experiments it might be inserted to transport models. moreover, databases of soil hydraulic and basic properties which have already been used in developing ptfs for estimating water retention might be applicable to create napl pollution sensitivity maps. in our study an organic liquid retention dataset from recently measured napl and water retention data of soil and mineral mixture samples was created. the fluid retention measurements were carried out with the pressure plate extractor method. furthermore, the basic soil properties, such as particle size distribution, organic matter and caco3 contents, and bulk density, etc. were also measured. according to our results, the van genuchten equation, having three parameters, could be perfectly fitted to the measured napl retention data as well as to water retention curves. preliminary analysis of the filtered dataset of 316 soil samples with pca showed strong correlations between the selected basic soil properties as well as fluid retentions of water and napl. the important role of organic matter and caco3 content in fluid retention of soils beyond the particle size distribution and bulk density was proved. the estimation methods for predicting the volumetric napl retention values of soils ptfs gave better results than the scaling method. as the parameters of napl retention curves were correlated (e. g. fitting with nonlinear regression might offer more than one possible solution), further research is needed to investigate the role of initial parameter values in fitting hydraulic functions to napl retention data. reliability of ptfs and the scaling method to predict the saturation values versus the pressure were compared. similar reliable estimations found when predicting the napl saturation values with scaling method and with ptfs. however, ptfs has been successfully applied to estimate the volumetric napl retention, more reliable than the scaling method. acknowledgements the authors gratefully acknowledge ágota horel and gábor barton, for their assistance in preparing the manuscript. we would also like to thank jenőné borbély, for the support in laboratory experiments at pannon university. this research was supported by the european union and the state of hungary, co-financed by the european social fund in the framework of támop-4.2.4.a/ 2-11/12012-0001 ‘national excellence program’. references acutis, m., donatelli, m. 2003. soilpar 2.00: software to estimate soil hydrological parameters and functions. european journal of agronomy 8 (3–4), 373–377. doi: 10.1016/s11610301(02)00128-4 fig. 5 reliability of estimating volumetric napl retention values with ptf and scaling methods par: the parametric method based on basic soil properties and their derived values; 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properties of european soils. geoderma 90, 169–185. doi: 10.1016/s0016-7061(98)00132-3 weawer, j. l., charbeneau, r. j., tauxe, j. d., lien, b. k., provost, j. b. 1994. the hydrocarbon spill screening model (hssm). 1. us epa. epa/600/r-94/039a. droughts and low water levels in late medieval hungary ii journal of environmental geography journal of environmental geography 10 (3–4), 43–56. doi: 10.1515/jengeo-2017-0012 issn: 2060-467x droughts and low water levels in late medieval hungary ii: 1361, 1439, 1443-4, 1455, 1473, 1480, 1482(?), 1502-3, 1506: documentary versus tree-ring (owda) evidence andrea kiss* institute for hydraulic engineering and water resources management, vienna university of technology, karlsplatz 13, 1040 vienna, austria *corresponding author, e-mail: kiss@hydro.tuwien.ac.at research article, received 5 october 2017, accepted 6 december 2017 abstract as a continuation of the first paper from the late medieval drought series related to medieval hungary, we present, analyse and compare further late medieval drought data, based on contemporary direct and indirect written sources. the evidence derived from documentary sources referring to the droughts and dry spells in 1361, 1439, 1473, 1480, 1482(?), 1502-1503 and 1506 are further compared to the recent tree-ring based hydroclimate reconstruction of the owda (old world drought atlas), and similarities, differences and complementary information are discussed in more detail. additionally, documentary evidence related to danube low water-levels of 1443, 1444, 1455 and 1502 are as well presented in a broader context: these cases provide evidence on the hydrological conditions of the upper-danube catchment, and not on the carpathian basin. the owda evidence in most cases shows good agreement with the discussed documentary-based drought reports, some differences in the spatial extension and intensity of the drought were only exceptionally detected (e.g. 1455, 1507). most of the written documentation refer to droughts that covered more than one calendar years. keywords: droughts, late middle ages, low water level, danube, documentary evidence, owda introduction in the present paper eleven confirmed or presumed drought years, occurred in the carpathian basin, are discussed based on direct and indirect documentary evidence, also taking into consideration the tree-ring based annual summer precipitation and spring-summer pdsi reconstructions of the old world drought atlas (see cook et al., 2015). as kiss and nikolić (2015) suggested in the first paper of the current series on medieval droughts, when reported, the memorable drought events are often one year after the western and west-central european ones in contemporary hungarian sources. nevertheless, indirect information in contemporary domestic sources or foreign documentation may also suggest that, in case of 1362, 1474 and 1507 already the year before, namely in 1361, 1473 and 1506, while in case of 1479 also in 1480, larger areas of the carpathian basin might have also suffered from the lack of sufficient precipitation. moreover, in some additional cases documentary evidence is available concerning drought years or very dry summers in 1439, 1482 and 1503, and in four additional cases, in autumn 1443, spring 1444, summer 1455 and probably also in autumn 1502 low or very low danube water levels were reported. combining and complementing the information presented by kiss and nikolić (2015) with the currently discussed evidence, on the one hand, in the present paper some "more complicated" and indirect source evidence is also analysed in a central european context. on the other hand, the information derived from documentary evidence is compared to the recently published, tree-ring based, annually resolved hydroclimate reconstruction available in the old world drought atlas (hereafter owda). additionally, in the present paper some auxiliary information on weather background (e.g. winter snow, heat, rainfall and flood reports) is also included. as large part of the annual precipitation in the most populated, major agricultural areas of the country fell in late spring and early summer time, and the cereal and hay harvests strongly depended especially on the may-june, and partly on winter(-early spring) precipitation, potentially there is a significant connection between reported droughts, usually mentioned in relation with harvest problems, and the evidence presented by the owda. furthermore, in case of the tree-ring based hydroclimate reconstruction, the precipitation conditions of the preceding autumn can as well influence tree growth (prokop et al., 2016). applied documentary sources and the owda database: strength and weaknesses documentary evidence as demonstrated by kiss and nikolić (2015), mainly individual reports on droughts are available in an increasing number towards the second half of the 15th 44 kiss (2017) century. these cases were usually recorded due to the impacts of droughts, and therefore the beginning of the drought period is rarely known, while some of the major consequences – either affecting transportation or harvest results – were mentioned in more detail. although it is clear that not all the late medieval droughts can be detected in this way, by the 15th century, especially concerning its second half, written documentation enables us to determine greater drought events that affected larger regions of the country. the presently discussed cases are mainly known from town and diocese accounts (1443-3, 1455, 1502-3, 1506), but narrative sources such as hungarian and german chronicles (years 1439, 1473, 1480) and charter evidence (1361, 1482) as well play an almost equal role in the available documentation. at present two account series are known that contain weatherand water-level related data in larger quantity: the pressburg/pozsony (bratislava-sk) accounts and the account books of the bishop of eger, ippolito d'este. both in source type and content, the short reports available in the accounts of the eger bishop (e. kovács, 1992), form a separate group: in these cases only very indirect information is available that generally suggest unfavourable conditions: through oneone bad year for bees with shortage of honey and wax, damaging thunder reports or significant loss of sheep we may presume previous unfavourable conditions that might have been partly (or mainly) related to droughts. as for the narratives, the thuringian chronicle of johann rothe refers to a drought in hungary under the year 1439, while the hungarian chronicle of antonio bonfini reports on droughts in 1473 and 1479. similar is true for the known charter evidence related to the drought in 1361-2, and the very dry summer of 1482 or 1483. concerning the calendar dating applied, in the present work the original dates in julian calendar are provided. nevertheless, in those cases when the difference between the julian and gregorian calendars affects the interpretation, also the gregorian calendar dates (hereafter gc) are provided in brackets. application possibilities of the owda evidence in drought severity detection of single years the recently published owda maps present natural hydroclimate variability based on tree-ring data in annual resolution: the maps provide june-august scpdsi (palmer drought severity index) information, and reflect on spring and summer soil moisture conditions year by year concerning the period between 0 ad to 2000 (cook et al., 2015). thus, it describes a key period from the viewpoint of, for example, agriculture, but does not offer an evidence on the precipitation or soil moisture conditions of the entire year. in generating the annuallyresolved maps, regression-based climate field reconstruction method has been applied which also means that in an area where no tree-ring based hydroclimate reconstruction is available, the closest available series will have the most influence and mainly this/these (and lesser extent the further-located series) will form the basis of extrapolation. in the owda database (cook et al., 2015), concerning the carpathian basin including the carpathian mountains, four series area available. the closest data series, and the only one that extends back in time to our late medieval study period with a sufficient amount of sample, is the recent millennial hydroclimate reconstruction of prokop et al. (2016). in this reconstruction the oak tree samples were derived from different parts of slovakia, from the northern parts of the carpathian basin, in the western carpathians. the reconstruction usually explains around or less than 50% of the variables, but correlation also varies over time. furthermore, whereas until the end of the 14th century the number of annual samples is rather low that determines applicability (see prokop et al., 2016: fig. 2a), from the early 15th century onwards the reconstruction is already based on a more sufficient, representative number of samples (exceeds ca. 30-50, and then 100). another important point of the reconstruction is spatial correlations: whereas the slovakian series shows the strongest correlations to the czech and western ukrainian series, this correlation is somewhat weaker, though still significant, with western, north-western and north-eastern hungarian series from hilly areas. as no tree-ring based hydroclimate series are known from, for example, the great hungarian (or pannonian) plain or central transylvania, it is not clear in what extent the prokop et al. (2016) series can describe the hydroclimate variability of these areas. we also have to account with other potential uncertainties. for example, it is generally also possible that after a significant drought year or years the tree ‘overreacts’ in the following year, and even if the year is not extraordinary humid, the tree produces the signs of very wet conditions. while, according to recent observations, this is clearly true on the seedling level (see e.g. turcsán et al., 2016), it is also a realistic possibility in case of the adult tree population that forms the basis of hydroclimate reconstruction (see dobrovolný et al., 2017). despite the fact that the reconstruction only covers the spring-summer period, and also the potential uncertainties that make tree-ring based hydroclimate reconstruction a safer tool for multiannual than annual comparison, the aforementioned owda maps and the database behind provide an exceptionally valuable, indirect source of information. its importance gets particularly high when, for example, in documentary evidence only indirect or non-contemporary sources, often with uncertainties in dating, reflect on one-one drought period. in these cases the tree-ring based hydroclimate reconstruction can support or weaken the validity of the information derived from documentary evidence. results the drought year of 1361 in the previous paper of the series (kiss and nikolić, 2015), spring 1362 drought information from dalmatia was presented, together with the presumed early grapevine harvest data, probably suggesting altogether droughts and low water levels in late medieval hungary ii 45 rather warm late spring-summer conditions in the budapest area in spring-summer 1362. as we could already see, in middle-dalmatia the drought started earlier, so that latest the winter could be notably drier than usual. from further, contemporary austrian charter evidence it is known that in 1361 there was very bad grain harvest in austria, in the czech lands and also in hungary (see e.g. csendes and oppl, 2001; rohr, 2007; kiss et al., 2016), but in austria already 1360 was a drought year (rohr, 2007). the fact that already in midspring 1362 the hungarian king prohibited grain export in dalmatia (in raguza/dubrovnik-hr) from his territories in general (gelcich and thallóczy, 1887), further supports the idea that bad-harvest problems affected large parts of the areas of the hungarian crown. in the meantime, most parts of western and central europe, including such neighbouring countries as poland, the czech lands and austria, faced with a serious drought in 1361, while in austria already 1360 was a drought year. furthermore, apart from the bad grain harvest in 1361, in austria vine harvest was reportedly bad as well (alexandre, 1987; brázdil and kotyza, 1995; rohr, 2007). in hungary bad or very bad grain harvests were often related to lack of sufficient amount and type of precipitation in the late spring-early summer period, and often already winter was (cold and) dry, then crops could not develop properly. in the middle ages such cases were reported, for example, related to the drought year of 1507 (see e.g. kiss and nikolić, 2015, kiss, 2017), but already the mid-14th-century biographer of king louis i, jános küküllei (florianus, 1884), listed drought among the most important factors being responsible for famines in hungary. as demonstrated by the owda maps (see fig. 1), based on tree rings, 1361 was particularly dry in summer, but soil moisture, very necessary to the development of crops, was perhaps at a loss in spring and summer. in case of such a very strong negative pdsi values, we cannot exclude the possibility that low soil moisture was already a problem before spring 1361. it is, however, and interesting fact that the winter or early spring of 1361 was not dry at least in some parts of the carpathian basin: for example, in early spring (possibly in march) along the ford between lake fertő/neusiedlersee and the hanság/wasen wetlands cold weather and much snow, while in mid-april the great mud obstructed perambulations (dreska, 2001). in the meantime, in the hilly north, in turóc county (today n-/nw-slovakia) the great snow similarly obstructed a perambulation in mid-march (hna dl 90540; see kiss, 2016). this is in slight contradiction with, for example, reports from austria and germany where this winter had a cold, but mainly dry character (see e.g. alexandre, 1987; brázdil and kotyza, 1995). combining the aforementioned indirect evidence, it seems rather probable that 1361, and spring-(early)summer in specific, was extraordinary dry, and to some extent this dry tendency also continued in (early) 1362. however, unlike in large parts of central europe, the winter of (1360-)1361 was not necessarily dry in hungary. 1439: very dry (spring-)summer in south-hungary? a rather interesting report was preserved in the german düringische chronik of johann rothe (liliencron, 1859), under the title "801. wie die torcken yn das lant zu ungirn quomen". according to the description, the summer of 1439 was dry in hungary, and the water called "mossir" also dried up ("nu was der sommer etzwas dorre unde trocken, alsso das yn den landin das wassir gnant die mossi r gar vertruckent was,..."). afterwards, the author fig. 1 tree-ring based hydroclimate reconstructions of the owda: 1361 and 1362 (cook et al., 2015) 46 kiss (2017) shortly described the turkish campaign and the hungarian military response, especially in the banat area that is today north-eastern serbia and southwestern romania. the description of the military operations fits the author's dating: in 1439 summer a significant turkish army first invaded serbia, and then indeed entered hungary, attacked the the banates of temes and szörény (centre: szörényvár/turnu severin-ro), the areas in south hungary most easily reachable both from serbia and valachia. the hungarian king, albert, sent an army (with jános hunyadi in lead) to defend especially szörény against the turkish attack (see e.g. bánlaky, 1931). there is no any known, significant water body in this area that holds the "mossir" name. however, it is possible that the word in the present case does not cover a proper noun, but it is a somewhat distorted form of the hungarian word of "mocsár" in the meaning of swamp or wetland. if the lowland marshes/swamps/wetlands "quite much" dried up, for example, in medieval southern hungary, this circumstance naturally provided more favourable environmental conditions for travel or military campaigns with increasing the possibilities of a quick march and swift attack. the original author of this volume, johann rothe (1360-1434), was the clerk or notary of the town eisenach in thuringia. nevertheless, he died in 1434, and the name of the author who continued his chronicle and also wrote the 1439 hungarian report, is unknown. even if it is rather possible that the author who continued rothe's chronicle was contemporary, missing the author's name, this statement cannot be proved with certainty. furthermore, the author's description most probably relied on the observation of other people, even if based on the potential interpretation of the word "mossir" we can raise the possibility that the person from whom the unknown author heard the 'story' could be from hungary. with regards to the dating of the event, as described above, there was indeed a siege of szörényvár (turnu severin-ro) and a military campaign of the hungarian army to serbia in summer-autumn of 1439 (see e.g. bánlaky, 1931). according to the tree-ring based hydroclimate reconstruction of the owda, around the turn of the 1430-1440s two summers were particularly dry in the carpathian basin: 1439 and 1440 (see fig. 2). the quite dry marshes(?), in accordance with the owda scpdsi values, may also suggest that this dry spell started earlier, and probably already spring was drier than usual and, as mentioned before, the political circumstances also support the author's dating of the event to 1439. furthermore, the fact that the turkish emperor, murad ii started his military campaign against serbia in late may (see e.g. bánlaky, 1932), and was already in the borderline area with his army in june, suggest a quick military campaign that is rather unlikely to happen, for example, in wet weather conditions. danube low water levels in autumn 1443 and spring 1444 although in the pressburg/pozsony (bratislava-sk) accounts references on floods appear much more often (see e.g. kiss, 2018), occasionally danube low water levels are also mentioned. in the first case, on 13 september (gc: 22 september) in 1443, the danube was noted for being very small (amb, k6/77: item am phinztag noch nativitate marie virginis hab wir land in daß wasser geczogen haben als di tuna gar klain waß…). furthermore, in next spring, on 11 april (gc: 20 april) 1444 a reference on small danube was again included in the accounts (amb, k7/171: item am fig. 2 tree-ring based hydroclimate reconstruction of the owda from 1439, and the reconstruction detail of the carpathian basin and its immediate neighbourhood (see cook et al., 2015) droughts and low water levels in late medieval hungary ii 47 sambstag am heiligen oster obund hab wir gehat xiiij aribater dy sannd uber dy tuna uber gepracht haben, in ainer zullen als dye tuna klain waß,…). as the danube low-water reports come in both cases from the area near the austrian borderline, the information holds a precious hydroclimate signal concerning the precipitation conditions of the preceding months, primarily referring to the upper-danube catchment basin. thus, these data do not directly reflect on dry periods in the carpathian basin, but they primarily correspond to the weather conditions of more westerly areas. it is interesting to further note that no flood was reported in the accounts between early august 1443 and mid-july 1444 (see kiss, 2018). nevertheless, while in july a danube flood was mentioned (amb k6/75), in mid-september the water level, reported by the same source in the same volume written by the same hand only three pages later, was already very low. in relation with the three low water-level mentions, concerning 1443 we can find a ‘perfect fit’ with the relevant owda map: based on tree-ring evidence in the (spring-)summer period, great drought prevailed in west-central europe in this year. the central european documentary evidence provides rather interesting though somewhat biased further information concerning the years 1443 and 1444: whereas the wine harvest was good at lake constance in 1443, which suggests overall warmer and drier summerearly autumn conditions, lower-austrian and czech sources speak about rains and windy conditions from midjuly, presumably also in autumn (see e.g. brázdil and kotyza, 1995). nonetheless, in fact the summer and autumn of the previous year, 1442, was memorably dry, followed by a cold and snowy winter that lasted until late april; in some areas snow even fell after that, in early may. the winter of 1444 started early and was memorably hard not only in central europe (brázdil and kotyza, 1995; rohr, 2007; glaser, 2013), but also in the balkan peninsula (e.g. telelis, 2008). in late autumn-early winter time a major military campaign, probably also supported by low waters and overall dry late autumn conditions on roads, was led by the hungarian king through the northern balkan as far as bulgaria and the black sea (see e.g. bánlaky, 1931). whereas the winter was dry in silesia, it was reported with abundant snow in bavaria, salzburg and klosterneuburg. furthermore, the winter in the czech land released only after 17 march (brázdil and kotyza, 1995; glaser, 2013). consequently, merely based on the information from central europe, the danube low water-level evidence dated to autumn 1443 and spring 1444 should be better dated to 1442 and 1443. the 'problem' in this case is that the pressburg accounts are very clearly dated: all previous and following entries could refer only to 1443 and not 1442 in the autumn case, while to 1444 and not 1443 in the spring case. furthermore, it is also highly unlikely that for works, carried out in 1442 the town would have paid with a year or even several months of delay (without even mentioning that). it is also an interesting fact that, while the dates in the relevant section of the accounts clearly and unambiguously refer to 1443 in volume (amb) k6 and to 1444 in volume k7, no information on low-water level conditions remained in the previous, 1442 (amb k4) and 1442-1443 (amb k5) volumes. it is, nevertheless, somewhat thought provoking that long-lasting and large-scale works took place in 1442 in the old tabor (riverbank, harbour) area, and this would have been rather difficult to carry out during the high water level or flooding of the danube. in the present case, the owda reconstruction plays a rather important role in sorting out the potential discrepancy in dating the (very) low danube water level fig. 3 tree-ring based hydroclimate reconstructions of the owda: 1442 and 1443 (cook et al., 2015) 48 kiss (2017) reports: according to the tree-ring based hydroclimate reconstruction both in 1442 and 1443 the (spring-) summer period was very dry in the upper-danube catchment area (see fig. 3). on the basis of this and the above-mentioned documentary evidence, it is possible that although dry conditions and low water levels already prevailed in 1442, due to particular works where related water-level conditions were mentioned, the source only mentioned the low water level of the danube when because of the payment conditions such an explanation was necessary in particular account entries, namely in autumn 1443 and spring 1444. low danube water level or not? the small-water reference in summer 1455 more than a decade later, the little extension of water was again mentioned in the pressburg accounts, at this time in summer: on 23 june (gc: 2 july) 1455 the small size of the river was noted (amb k22a/47: item und haben auch gehabt besundere ij aribater pei dem hanns stewber pinter die pewsch gelegt haben als die tuna klain waß die dass wasser zu dem wasser rad gelait haben …). the text clearly refers to low waterlevel conditions of the danube river, in the pressburg/pozsony (today bratislava-sk) area, and also the late june 1455 dating is accurately provided (previous and following dates all belong to the year of 1455) in the account book. with regards to the potential, documentary-based weather-related parallels in the neighbouring countries, in 1455 the winter was hard and lasted until the end of march in bohemia, but the spring and particularly the summer could be warm. in summer, heat and great drought was recorded in silesia (brázdil and kotyza, 1995). no information is available concerning the spring, but according to glaser (2013), the summer was wet and infertile in the german areas. except for the eastern alpine area where mainly dry weather conditions prevailed, the relevant map of the owda also shows slightly wet conditions in the upper-danube catchment basin, especially in bavaria, even if dry conditions prevailed in large parts of austria (fig. 4). in conclusion, although the czech and silesian sources rather refer to a warm and dry summer, the german reference, partly in accordance with the owda evidence, clearly mentions it to be wet. at the moment we cannot solve this apparent contradiction, but it is clear that the pressburg accounts item is accurately dated, and clear about the danube low water level. however, as the information comes from early summer, it is probable that more significant precipitation occurred after this date, and it might be also possible that the eastern alpine catchment basin of the danube was predominantly dry in (spring)early summer, and this circumstance influenced the water level conditions of the danube in eastern austria and hungary. drought in 1473, and 1474 revisited in relation with the "perennial" drought report of the contemporary chronicle writer, antonio bonfini, who dated the event to 1474, three other, non-contemporary sources were listed by kiss and nikolić (2015) considering a great drought, referred under the year 1473. while one of the non-contemporary sources, the compilation of the swiss lycosthenes, was written in the mid-16th century, two other, 17th-century chronicles, the chronicle of leibic/leibitz (l'ubica-sk) town and the chronicle of caspar hain from lőcse/leutscha (levočask) both from the szepesseg/spiš region (today in neslovakia), reported on a great drought that happened in 1473 (for references, see: kiss and nikolić, 2015). thus, on the one hand, a contemporary report is available on a great drought written by bonfini, a contemporary author of italian origin, who later lived fig. 4 tree-ring based hydroclimate reconstruction of the owda from 1455, and the reconstruction detail of the upper-danube catchment basin (see cook et al., 2015) droughts and low water levels in late medieval hungary ii 49 in hungary, wrote the most detailed and accurate history of hungary of his time, clearly gained his information from eye-witnesses in hungary, applied thorough source critics, and accounted for being a most reliable author of the reign of king matthias (1458-1490; see e.g. klaniczay, 1974). bonfini's report provides 1474 dating, with suggesting a long-term drought that allows an interpretation of an event that lasted longer than a year and thus, does not exclude a 1473-1474 dating either, especially, because the author also refers to parallel turkish attacks that happened both in 1473 and 1474 (see e.g. bánlaky, 1932). on the other hand, three non-contemporary chronicles, two of them from hungary and another one from switzerland suggested 1473 as the great drought year in hungary, and none of the three mentioned 1474 in connection with drought. and while, according to the contemporary documentation, 1473 was a great drought year in central europe, including the czech lands, poland, the german areas, switzerland as well as austria (see e.g. brázdil and kotyza, 1995; glaser, 2013), the sources were mostly silent about the character if 1474 in the same areas. thus, in this case we have a rather unique situation as the only contemporary narrative that reported on the drought provides a somewhat different (even if no fully contradicting) dating than the non-contemporary chronicles, and the evidence from the neighbouring countries more supports the dating of the non-contemporary sources and not that of the contemporary one. the relevant owda maps, however, show that in the carpathian basin there were considerable (spring-) summer dry spells both in 1473 and 1474, even if 1473 seems to be generally more extreme, especially in the northern half of the basin (see fig. 5). nonetheless, in the southern part of medieval hungary, including the southern borderlines of the kingdom, the drought of 1473 does not appear to be considerably more severe on the owda maps than in 1474. further documentary-based (even if indirect) information may provide some additional help to solve potential contradictions. as for bonfini, in his work on the hungarian history, the drought was only a background information that helped him in the description of military processes (see kulcsár and kulcsár, 1974). thus, he probably mentioned drought only when he felt it necessary in his explanations, while only briefly referred it without specification on date or location (as a circumstance that made turkish attack easier) when his text did not need this kind of auxiliary information. moreover, he gained large part of his information about these years from eye-witnesses in or related to the royal court: these eye-witnesses were likely to be the soldiers, or even leaders of military operations, who participated in the military campaigns leading to the south, towards the territories occupied by the ottoman empire. these military campaigns, however, mainly took place in 1474 (see e.g. bánlaky, 1932; klaniczay, 1974) and not in 1473, and therefore the potential hungarian eye-witnesses could have personal experience, at least through large part of the country including the southern borderlines, mainly in this year. the extensive wetlands of the lowland areas usually needed longer period of time to dry up: if there was a severe drought in 1473, and 1474 was also dry, the really visible consequences, for example, in the extension of stagnant water bodies or the height of groundwater table could be perhaps even more apparent in 1474 than in 1473. additionally, a silesian source may shed more light on the character of 1474 in the close neighbourhood of the carpathian basin. the contemporary silesian chronicler, peter eschenloer (roth, 2003; gyalókay, 1940), while describing the successful military campaign of king matthias against the polish king in silesia, noted that the water level of the oder/odra was low in early october 1474 at krappitz (krapkowice-pl), when the polish army crossed it. this fact suggests overall dry preceding conditions in the southern silesian catchment fig. 5 tree-ring based hydroclimate reconstructions of the owda: 1473 and 1474 (cook et al., 2015) 50 kiss (2017) basin of the river prior to early october, while the polish chronicle writer, jan długosz, in november mentioned heat and drought (length not defined), and then a flood of the oder/odra that had been caused by rain (bazkowski et al., 2005). consequently, in accordance with the aforementioned documentary and tree-ring based evidence, and also with reference to the part-conclusions of kiss and nikolić (2015), we suggest that both 1473 and 1474 could be years with more significant water deficit in hungary and the carpathian basin, even if the intensity of this dry spell and drought may have had spatial and temporal differences within the carpathian basin. religious procession praying for rain: great spring (and summer?) drought in 1480 briefly referred by kiss and nikolić (2015), following the inquiry of king matthias i, the pauliners of budaszentlőrinc made a religious procession in (late?) spring, from budaszentlőrinc to the castle of buda, carrying the relics of the saint (paul) with them, and praying for rain in the "great drought". however, it started raining before the procession could have turned back to the monastery, and the vegetation recovered (gyöngyösy, 1988). this information is particularly interesting as the only available report, antonio bonfini’s extensive chronicle, suggests 1479 as a memorable drought year, and does not mention dry conditions for 1480 (kiss and nikolić, 2015). nonetheless, in, for example, the czech lands 1480 was marked by its characteristic dry nature and not 1479. another additional, indirect evidence, similarly dated to 1480, might be worth to be mentioned here: the judge of (buda)felhévíz warned the tax-collectors to the royal charter that stated their tax-free status on their own cargo ships carrying food (bártfai szabó, 1938). although such a case could happen any time, there is somewhat more chance for food-related conflicts, for example, in times with food shortage problems. it has to be further noted that, documented in the pressburg accounts, in early summer 1480 there was a danube flood of moderate intensity in the bratislava area (see kiss, 2018). as presented on the related owda maps (fig. 6), 1479 was a significant drought year concerning at least the (spring-) summer period practically all over europe, while 1480 was more concentrated to the southern, south-eastern parts of the continent, including the carpathian basin. nevertheless, on the tree-ring based hydroclimate reconstruction map the carpathian basin seems to be strongly affected by drought in both years, and therefore in this case – in agreement with the direct and indirect documentary evidence – we have to account with a double drought-year in hungary. "in aestate ultra arida"very dry summer in transylvania: 1482? in a charter dated to 19 february 1496 (iványi, 1928), the nobles of pókafalva (păuca-ro) in south-eastern transylvania, preserved an earlier complaint against the people of the pauline friary: in 1482 there was very dry summer, and the serfs ("layci nostri") of these nobles drove their draught animals to a fishpond, constructed in 1475, to drink. they went there three times, and finally armed men of the friary came, and gravely injured with their swords two serfs of the nobles ("in anno quidem domini millesimo quadringentesimo octuagesimo secundo in aestate ultra arida cum layci nostri ad adaquandas iumenta ipsorum ad piscinam dictorum fratrum depulissent, tunc prior praefatorum tertiusmet sibi similibus, armatis manibus de claustro irruentes, duos ex laicis nostris cum gladio letaliter vulnerarunt...."). the most important, weather-related information of this story is that in 1482 the summer was memorably dry, but there was enough water in the local fishpond to serve as a water supply for large domestic animals. fig. 6 tree-ring based hydroclimate reconstructions of the owda: 1479 and 1480 (cook et al., 2015) droughts and low water levels in late medieval hungary ii 51 the charter was written almost 14 years after the event. although legal documents, and charters in particular, form a most accurately dated source group, in the present legal procedure the fact that the event happened particularly in 1482 did not play a central role in the legal case and thus, we cannot completely rule out the possibility that the event occurred one year earlier or later. nevertheless, as the charter itself referred back to 1482 specifically as a (memorable) summer of great drought, it is probable that the event was not misdated, and potentially many eye-witnesses still could confirm the dating. taking into consideration the owda reconstruction (fig. 7), however, we can see that 1483 (or even 1484) would be a more likely option for a particularly dry summer in transylvania. according to the owda, 1482 was although dry, it did not represent a particularly dry period in transylvania. nonetheless, since the owda provides information mainly on (spring-)summer patterns, this might be also in connection with spring (or even earlier) precipitation. north, north-east to transylvania, the areas what is today the ukraine show extreme dry patterns for the (spring)summer of 1482, which may indirectly support the theory of a very dry summer in large parts of transylvania, too. therefore, although we cannot exclude the possibility that the year 1482 was mentioned in the charter by mistake instead of, for example, 1483, it is also possible that the charter evidence provide in this case a more accurate information than the owda data. loss of bee, grain and vine harvest, high prices and low water level: indicators of a dry spell in 1502 and 1503? in hungary, no contemporary source is known that directly refers to any dry spell or drought in the years 1502 and 1503. nevertheless, some indirect evidence suggests that considerably dry conditions. on 29 november (gc: 9 december) in 1502 the small water is mentioned in the pressburg accounts (amb, k58/34: item kamerer hat hingeben ain alte pletten ausß dem urfar denn ungern in das klain wasser zw dem thaman sthoff…). the phrasing of the sentence less obviously refers to general low water levels than the ones in 1443, 1444 and 1455. still, in the text clearly a danube trajectory and a ship are mentioned, and the sentence is regarding to the actual conditions of a danube branch. however, as the text refers to an old ship, the most possible option is that the small extension of the water was emphasised because this important circumstance influenced, either positively or negatively, the conditions of removal. although the reference is dated to late autumn-early winter times, it is worth noting that the owda map for (spring-)summer 1502 shows rather dry conditions in western and west-central europe including the majority of the upper-danube catchment basin, and the dry character of the autumn could have further supported the development of a dry spell that resulted the 1503 extreme low tree ring values (see fig. 8). documented in a number of contemporary sources and presented by the relevant owda map (fig. 8), 1503 is a well-known severe drought year in western and central europe, also including, for example, the czech lands, poland, austria or the german areas (see e.g. brázdil et al. 2014; rohr, 2007; glaser, 2013). thus, both 1502 and 1503 were drought years in western and north-western europe, but in (spring)summer 1503 the drought was considerably more severe. according to the above maps (fig. 8), however, the carpathian basin would have been less affected in 1502, and even in 1503 the drought could have appeared in a significantly milder form than in the west. however, it is interesting that while on the owda map the central and eastern parts of austria, fig. 7 tree-ring based hydroclimate reconstructions of the owda: 1482-3 (cook et al. 2015) 52 kiss (2017) similar to most of the carpathian basin, do not belong to the areas notably affected by severe drought, the chronicle of lorenz mittenauer in wels (upperaustria) clearly emphasised the extreme drought of 1503 and its unfavourable consequences (including devastating hails) on cereal and hay harvest as well as on fish supply (see rohr, 2007). it is also interesting that, based on documentary evidence, in the czech lands there were droughts in 1501, 1503 and 1504, too. in 1502 or 1503 no direct source refers to a drought in hungary. nevertheless, in the rather detailed accounts of the bishop of eger (source: e. kovács, 1992) many entries are related to certain problems that later, in 1507, again appear in the accounts when drought and related damages are listed (see kiss and nikolić, 2015; kiss, 2017). even if the full account book is not available for 1502, rather interesting information is known from the 1503 accounts both concerning 1502 and 1503. no drought was directly mentioned, but much more is known concerning the damaging hails. mentioned on 14 february 1503, vineyards were previously damaged by hails in borsod county (e.g. boldva, varbó; ne-hungary): this evidence most probably refers to hails that still occurred in 1502. furthermore, the high prices of "all things" were mentioned in eger on 1 march 1503: this information may suggests harvest problems already for 1502. damages due to hails, bad weather, or simply the great damages in vineyards without mentioning the cause, occurred in 1503, were reported in the bishop's accounts concerning kaza in zemplén county (also heavily affected area in 1507: see kiss, 2017), sajószentpéter in borsod county, (olasz)liszka, gálszécs (sečovce-sk) and nádasd (tornanádaska) in újvár county. except for gálszécs/sečovce in south-eastern slovakia, all settlements are located today in north-eastern hungary, in borsodabaúj-zemplén county. in the vine region of the eger diocese (i.e. gyöngyös, gyöngyöspüspöki, solymos) part of the wine went bad ("rotten") in this year. damages by hail or simply bad harvest were also reported in szabolcs county (nádudvar, hegyeg) where spring cereals and the oats were destroyed. as presented by kiss and nikolić (2015) and kiss (2017), similar problems were typical during the 1507 drought event. another negative circumstance was mentioned concerning eperjes (prešovsk): due to fire, the town received tax release in this year. a further problem, again rather similar to those described in 1507, was the low income or complete failure in bee products. even if in 1503 this was mentioned in less cases than in 1507, it could be still a significant general problem in the area of the diocese, especially because larger areas, entire districts, for example the szántói district in szabolcs, the homonnai (humenné-sk), varannói (vranov nad topľou-sk), sztropkói (stropkov-sk), nagymihályi (mihalovce-sk) districts in zemplén, the kazai district in borsod county and the entire újvár county had no beehives to send to the castle (eger) in this year. as bees usually react rather sensitively on weather extremes, and this is particularly true in case of drought (or very wet conditions), similar to 1507 (kiss, 2017), they may act as indicators of weather-, and probably (spring-summer, or earlier) droughtrelated problems in 1503. thus, although currently no contemporary documentary evidence mentions drought related 1502 or 1503, it is clear that both years were problematic in some (e.g. the north-eastern) parts of the country, and based on the parallels of the neighbouring countrie s as well as the relevant owda maps, we may raise the possibility that dry conditions prevailed in some parts of hungary in 1503, and probably also in 1502. it has to be further added that, despite drought problems, probably not the entire year or years of 1502 and 1503 were dry, and even water surplus might have caused problems in this period. for example, on 6 may 1503 a letter written by the king to the royal town of fig. 8 tree-ring based hydroclimate reconstructions of the owda: 1502 and 1503 (cook et al. 2015) droughts and low water levels in late medieval hungary ii 53 pozsony (bratislava-sk) informs us about the severe problems caused by the frequent great floods ("ex frequenti illuvie aquarum") in the area of the town (hna df 240970; see kiss and laszlovszky, 2013), while according to rohr (2007) there was a great flood with significant damages on the river traun in september 1503 at wels in the catchment basin of the upper-danube. this flood, together with the potential flood of other rivers in the eastern alpine area, might have also influenced the water-level conditions of the danube in hungary. loss of sheep, high prices and convective events: indirect indicators of a drought in 1506? as presented by kiss and nikolić (2015), 1507 was mentioned by different sources as a memorable drought year in north-eastern part of the kingdom, that is today north-east hungary, eastern slovakia and south-western ukraine. the other contemporary source, jános kakas in buda, however, mentioned this drought related to the entire kingdom. nonetheless, in most parts of central europe rather 1506 was reported in contemporary sources as a year with great drought. the relevant owda maps (see fig. 9) concerning the years 1506 and 1507 show conditions considerably drier than usual, but according to these maps, a notable (spring-)summer drought anomaly could be detected especially in the southern and the north-eastern part of the carpathian basin in 1506, and only in the southern parts we see a greater drought anomaly in 1507. in general, based on the owda maps, both years were rather dry especially in the south, but drier conditions would have prevailed in large part of the carpathian basin in 1506 than in 1507. both the information coming from documentary evidence of the neighbouring areas (where detectable) and the tree-ring based hydroclimate reconstruction suggest dry conditions or drought in 1506 in central europe, even if the data based on the tree-ring reconstruction suggest a less significant drought event than what is known from documentary evidence. in hungary no contemporary report is known that directly mentions 1506 as a year of drought. nevertheless, some indirect evidence suggests that weather/environmental conditions were unfavourable not only in 1507 but already in 1506. as presented in table 1, the church of saint john burnt down in summer 1506 due to thunder in eger (see table 1), which means that a significant convective event occurred. other convective events had resulted the damaging hails that caused particularly great damages, most probably in 1506, in tolcsva that belongs to the tokaj-hegyalja wine region. the lamb tithe problems in sáros county (table 1; today n-ne-slovakia) probably refer to feeding/nutrition problems and/or disease in the 1506, but no details are known. however, according to the relevant owda map this was one of the areas affected the most by drought in 1506 (see fig. 9). in march 1507 there were only a few sturgeon and other fish in tisza: this fact most probably refers to preceding low water levels, and reflects on the precipitation patterns of a period that covered at least several months prior to the date of mention and thus, most probably already in 1506 the prevailing water levels were lower than usual. as the catchment basin of the upper-tisza covers the northeastern part of the carpathian basin (ne-slovakia, swukraine) as well as northern transylvania (n-romania), in these areas at least the second part of 1506 had to be drier than usual. unlike in 1507 when it seemed to be a significant problem, based on the bishop's accounts, there were no bee-related problems or lack of bee-products mentioned in 1506. however, the full accounts concerning 1506 are missing, and only the references remained in the 1507 accounts are known. thus, the lack of reference on the problem may not automatically refer to the lack of problems. fig. 9 tree-ring based hydroclimate reconstructions of the owda: 1506 and 1507 (cook et al. 2015) 54 kiss (2017) comparing the owda map with the available indirect documentary evidence, it is thought-provoking that in 18 april 1507 the king in a dramatic letter asked the citizens of sopron royal town to send a 1000 golden forint as a special military tax, because he urgently had to pay the soldiers at the southern borderline, due to their extreme great need ("extreme inopie magnitudo"; házi, 1928). this dramatic tone and the grave problems along the southern defence line can be, of course, always explained by the ever-uncertain military situation, as turkish troops could attack the area any time. the long-term expenses of the mere maintenance of this long defence line in itself meant a significant burden on the annual royal budget. nevertheless, taking into consideration the relevant owda map which shows that in 1506 the southern part of the country was the most affected by drought, it is also possible that in spring 1507 the very high price of food was an even more striking problem in the south than usual. given the fact that the king was late with the soldiers' payment, they most probably had severe food supply problems that threatened the southern fortresses with desertion. thus, apart from the general political and socio-economic problems of the south, we might also have to count with the negative effects of actual weather conditions. conclusions and outlook in the present paper, based on direct and indirect, mainly contemporary source evidence and also on the basis of the owda maps eleven years with dry spells were discussed. seven of the discussed cases were suggested as drought events occurred in some parts of the carpathian basin, while in further four cases low waterlevel reports were discussed in more detail. the known low water-level reports in 1443, 1444, 1455 and 1502, were all documented in the pressburg accounts, and refer to the danube in the bratislava area, and therefore primarily reflect not on the precipitation deficit of the carpathian basin, but rather that of the catchment basin of the upper-danube, including bavaria and the eastern alpine area (austria). as presented throughout the paper in a number of case studies, when documentary evidence is available, usually there were not only one but two years affected by drought. in this way, although directly the next (or previous) year was more emphasised in 'local' documentation, some of the great european drought years (e.g. 1473, 1480, 1506) could be also detected regarding late medieval hungary. moreover, in some cases it is probable that among the coupled drought years not necessarily the drought year, most severe in western or west-central europe, was the more severe in the carpathian basin. due to the characteristics of source types applied, it is also a possible option that while one drought year was (occasionally) mentioned in a contemporary domestic source due to related consequences, the other, similarly important (preceding or following) drought year remained unreported or can be detected only in the indirect evidence. this is true not only for the direct drought references, but also to the other important source group that concerns danube low water levels. for example, the 1443 or 1444 low waters were recorded in relation with particular activities, and therefore even if the previous year would have meant a similar or even greater anomaly, could easily remained unreported. furthermore, in some of the cases it is also possible that while in the first year one part of the country was more affected, in the other year the drought was more severe in other parts (e.g. 1473-4, 1506-7). the owda maps also show that, even if there were anomalous drought years that affected majority of central and western europe, similar to modern droughts, in most table 1 problems mentioned in the accounts of the eger diocese (source: e. kovács, 1992; see also: kiss, 2017) date of account location /county bad harvest or other damage tax release, postponing weather-related evidence 24.07.1506 gc: 03.08 eger st. john church burnt struck by thunder after 15.12.1506 gc: 25.12 buda, pest flood very great danube ice and coldness before 02.02.1507 gc: 12.02 szabolcs county losses (from 1506?): lamb tithe paid together with the 1506 lamb tithe 02.02.1507 sáros county lamb tithe: low income 14.03.1507 gc: 24.03 tolcsva (zemplén county) wine tithe: very great damages in vineyards 12 ft tax release due to previous damages, and for public works hails (probably in 1506) 25.03.1507 gc: 04.04 kürt (at the tisza river) few fish (sturgeon, other fishes) 24.04.1507 gc: 04.05 felnémet (heves county) poverty of serfs full release of remaining tax due to much public work droughts and low water levels in late medieval hungary ii 55 cases we have to account with considerable spatial differences not only between the different parts of europe, but also compared to the neighbouring countries, and even within the carpathian basin itself. although occasionally, especially concerning intensity and spatial extension of one-one significant drought events, some differences occur (e.g. in 1507), in most cases we found fairly good agreement between the (spring-)summer hydroclimate reconstruction of the owda and the documentary-based drought information. moreover, in some cases the owda map provided a good support to the identification of drought years, documented only in one contemporary source in hungary, but with scarce or no parallel information in the neighbouring countries. this might be particularly important in case of two or more drought years in series (e.g. 1442-1444). we also have to add that, rather clearly, many of the dry spells, captured in tree-ring evidence, still could not be detected in the domestic written documentation. however, rather indirectly other sources (e.g. food shortage problems and the owda-based long drought periods), not (yet) discussed in this and the previous paper, may provide further data that helps to capture more signs of severe droughts in late medieval hungary. the 15th-century dry spells, detected in written sources, are to some extent clustered around two periods: the first such period is the late 1430s-early 1440s: here 1439, 1443 and 1444 addressed in documentary evidence. nevertheless, the owda as well as the information from the neighbouring areas suggest that also years in between (i.e. 1440, 1442) were considerably dry in central europe and probably also in hungary, in the (spring-)summer period. taking into consideration also the evidence presented by kiss and nikolić (2015), the other such period is concentrated around the 1470s-early 1480s. references alexandre, p. 1987. le climat en europe au moyen âge. contribution à l’histoire des variations climatiques de 1000 à 1425, d’après les sources narratives de l’europe occidentale. éditions de l’école des hautes études en sciences sociales, paris, 488– 493. amb = archív hlavného mesta sr bratislava (bratislava municipal archives), magistrát mesta bratislavy (town council of bratislava): kammerbücher (xxiv.-1): 1443: k6/75, 77, 1444: k7/171, 1455: k22a: 47, 1502: k58/34. bazkowski, c., kowalczyk, m., ożóg, c., prożyńska, c., turkowska, d., wyrozumski, g. 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(ed.) 2003. peter eschenloer geschichte der stadt breslau. vol. 2. waxmann, münster, 948. telelis, i.g. 2008. climatic fluctuations in the eastern mediterranean and the middle east ad 300-1500 from byzantine documentary and proxy physical paleoclimatic evidence – a comparison? jahrbuch der österreichischen byzantinistik 58, 205. doi: 10.1553/joeb58s167 turcsán, a., steppe, k., sárközy, e., erdélyi, é., missoortan, m., mees, g., mijnsbrugge, k.v. 2016. early summer drought stress during the first growing year stimulates extra shoot growth in oak seedlings (quercus petraea). frontiers in plant science 7, 193. doi: 10.3389/fpls.2016.00193. introduction applied documentary sources and the owda database: strength and weaknesses documentary evidence application possibilities of the owda evidence in drought severity detection of single years results the drought year of 1361 1439: very dry (spring-)summer in south-hungary? danube low water levels in autumn 1443 and spring 1444 low danube water level or not? the small-water reference in summer 1455 drought in 1473, and 1474 revisited religious procession praying for rain: great spring (and summer?) drought in 1480 "in aestate ultra arida"very dry summer in transylvania: 1482? loss of bee, grain and vine harvest, high prices and low water level: indicators of a dry spell in 1502 and 1503? loss of sheep, high prices and convective events: indirect indicators of a drought in 1506? conclusions and outlook references journal of environmental geography journal of environmental geography 6 (1–2), 9–19. doi: 10.2478/v10326-012-0002-4 issn: 2060-467x studies of oxford stone as a contribution to environmental geomorphology mary j. thornbush school of geography, earth and environmental sciences, university of birmingham, edgbaston, birmingham, west midlands b15 2tt, united kingdom e-mail: m.thornbush@bham.ac.uk research article, received 12 december 2012, published online 15 april 2013 abstract much scientific research has been conducted on oxford stone, of which the historical buildings of central oxford, uk are comprised. this paper reviews all published literature to-date specifically for oxford stone, compiling an inventory of studies. the context for this review is in the application of environmental geomorphology to the more recent studies by physical geographers. overall findings across published studies assist with an understanding of current trends in the conservation of oxford’s historical buildings. early observations remain generally representative of the findings, although the more recent literature has employed modern methodologies in science and technology that were not available in the late 1940s. some indication of remaining research gaps are identified and forthcoming research presented. last is a discussion of current practice in the cleaning and replacement of building stone that briefly considers the authenticity of oxford stone, which is relevant for heritage conservation. the contribution of such studies to environmental geomorphology is addressed. keywords: limestone, historical buildings, soiling, human-environment relations, photogeomorphological approach, conservation, authenticity introduction the search for contextual similarities between traditional landscape analyses and heritage-orientated research much research has been published over the years on oxford stone that has contributed to a better understanding of the degradation and deterioration of building stone. geologists and geomorphologists at the university of oxford have examined the various types of limestone comprising oxford’s historical buildings. the emphasis shifted from a focus on the stone and different types of limestones and their sources from local quarries (in oxfordshire, but also further afield in leicestershire and gloucestershire, etc.) to environmental geomorphological studies of the impacts of air pollution on weathering and the condition of the buildings. most recently, a photogeomorphological approach was taken up (thornbush, in press a), where the buildings were depicted as they appeared in photographs from archival and recent records. this paper reviews the more prominent published studies for oxford stone. it begins from the earlier work of the geologist w.j. arkell, who was a senior research fellow of new college in 1933-1940, and continues with more recent works, including by physical geographers, such as by h.a. viles since 1996, when geomorphologists began to examine oxford’s historical buildings in the context of heritage conservation. these later studies are considered to be exemplar of environmental geomorphology, as a subfield of geomorphology that is within an applied geomorphology (fig. 1). this has two branches connected with environmental geomorphology, and specifically human-environment relations, comprising physical (natural) and human (cultural) components of landscapes. the geologist coates (1971) introduced environmental geomorphology as part of the then emerging field of environmental geology. according to him, environmental geomorphology ‘...is very broad and diverse, and includes [humans] and [their] role in terrain activities’. this breadth complicates the task of fully covering the topic. papers contained within the compilation had been presented at the environmental geomorphology symposium held in the department of geology, state university of new york at binghamton on 16-17 october 1970. he presented the subject content in three parts: 1) watershed planning; 2) regional and local studies; and 3) societal and educational perspectives. this was to commemorate the ‘environmental decade’ (of the 1970s), and the conference was devoted to examining the role of the geomorphologist in environmental studies. he armailto:m.thornbush@bham.ac.uk 10 thornbush (2013) gued that ‘...during these times of urban renewal and suburban sprawl, the growing population with its accompanying displacements, the rapid expansion of highway networks, and various terrain distortion activities, the geomorphologist has all too often been passive or played only a subsidiary part in any planning or decision-make process’. this stance was developed from the address of interdisciplinary approaches to water resources, as at a drainage basin in southern new york, and the emergence of environmental research in geomorphology. pending on this and other developments, environmental geomorphology was born out of environmental geology, which itself addresses: ‘1. physical data on the terrain itself; 2. data for management and disposal of wastes; 3. data for water resources development; and 4. data on the full range of usable rock and mineral materials and subsurface fluids’ coates (1971). he finally defined the subfield as follows: environmental geomorphology is the practical use of geomorphology for the solution of problems where [humanity] wishes to transform landforms or to use and change surficial processes. obvious candidates for this study, interpretation, and planning include land-fill operations, ground-water mining and subsid ence, streamflow regime upsets, and hillslope modific ations. in addition, environmental geomorphology includes extraction of surficial materials, and protection of certain landscapes, such as beaches, which benefit [humanity]. the goal for geomorphic environmental studies is to minimize topographic distortions and to understand the interrelated processes necessary in restoration, or maintenance, of the natural balance. in this way, coates established human-environment relations conceptually within his notion of an environmental geomorphology. he followed this up with a subsequent publication (coates, 1972), wherein he identified various issues and themes concerning environmental geomorphology. these specifically included the following: ‘1). the study of geomorphic processes and terrain that affect [humanity], including hazard phenomena such as floods and landslides. 2) the analysis of problems where [humanity] plans to disturb or has already degraded the land-water ecosystem. 3) [humanity’s] utilisation of geomorphic agents or products as resources, such as water or sand and gravel. 4) how the science of geomorphology can be used in environmental planning and management’. there was much response to coates’s (1972) environmental geomorphology and landscape conservation, especially volumes ii (on urban areas) and iii (nonurban regions). dury (1975), for instance, found the second volume to be better than the first (which is mostly unaddressed in book reviews and editorials), even though he found that contribution to be mainly representative of the urban theme in the usa (for example, california) and, hence, fails to address problems on a global scale. there is also a lack of address of karst development for urban areas. jacobs (1977) was more impressed by the 75 pages written by the editor, comprising coates’s overview, text, and references that were considered to be more helpful than the collection of articles. for the latter volume (iii), gregory (1974) acknowledged an awareness of contemporary problems deriving both directly and indirectly from human activity (as presented more recently in panizza’s (1996) model of the relationships between the geomorphological environment and humans; refer to his fig. 1). the author also appreciates the temporal span of articles represented in the volume, since 1900 (with volume i covering the literature before 1900). he also remarks on the 10% of content written by the editor that effectively outlines the content of the papers, with introductions provided for the three main sections (organised according to the following topics: terrain degradation; soil conservation; and landscape fig. 1 the placement of environmental geomorphology within geomorphology studies of oxford stone as a contribution to environmental geomorphology 11 management). the volume contains some rare papers and brings together relevant studies for the subject matter, such as concerning landscape management. ofomata (1974) considered this anthology to be the most important as it fills a gap in the literature; however, it did not completely portray nonurban environments through the exclusion of the african (for which papers are mainly written in french and should have been translated and included in this volume) and latin american continents. again, the volume is dominated by american studies, with some additional coverage of australia, china, israel, japan, and russia. panizza (1996) recognised the contribution of verstappen (1983) for definition of environmental geomorphological issues. like briggs (1981), panizza (1996) envisioned environmental geomorphology to encompass human-environment relationships from a geomorphological perspective, with the environment approached from an ecological sense. he subdivided geomorphological components into: ‘...geomorphological resources [(raw materials relevant to geomorphological processes and landforms)]; and geomorphological hazards [(associated with geomorphological instability)]’. within this environmental component, humans represent: ‘...human activity [(identified as ‘...hunting, grazing, farming, deforestation, utilisation of natural resources and engineering works’)]; and area vulnerability [(occurs due to human intervention, such as ‘...population, buildings and structures, infrastructures, economic activity, social organisation and any expansion and development...’)]’. around this time, coates (1982) also published in the book applied geography: selected perspectives. his paper on environmental geomorphology perspectives addressed its potential contribution to land-water ecosystems and focussed on food, population, and energy. subsequent books included developments and applications of geomorphology, where fisher (1984) discussed coastal environmental geomorphology in applied coastal research. environmental and dynamic geomorphology included a paper on environmental geomorphology in hungary by pécsi (1985), as a part of applied geomorphological research. geomorphology and environmental changes in tropical africa was a special publication that included a paper on the fluvial environment of the tana river, kenya by ojany (1986) that addressed environmental geomorphology. physical geography and geomorphology in hungary also contained a paper by pécsi (1986) that comprised of problems involving the utilisation of the environment. in addition to these earlier books on environmental geomorphology, papers were also disseminated explicitly as part of international conference proceedings. for instance, the proceedings of igarss ’84, strasbourg, france, where environmental geomorphological studies in the himalaya, india were based on the analysis of aerial photographs and satellite images and gave consideration to the degeneration of environment (prasad et al., 1984). prasad (2008) subsequently published a book on environmental geomorphology that defined it as ‘...the scientific study of morphological process and landforms with respect to nature’ (preface). he stipulated that the subdiscipline is primarily concerned with surficial physical features of earth history. however, he acknowledged that these earth processes and landforms are influenced by human interactions, what he referred to as ‘ecoculture’ or ‘physico-cultural phenomena’, which is particularly prevalent in the ‘techno-scientific era’. at this time, humanity has destroyed nature due to its constructions and contributed to ‘eco-degradation’ hazard, ensuing on what he terms an environmental disaster that has challenged scientific research and spurred the need for ‘eco-protection’, causing geomorphology to meet with environmental science. the author mentioned relevant problems, such as the protection of environmental diversity, establishing ecological balance, and ‘ecodevelopment’ as part of conservation. environmental geomorphology’s connection with the earth sciences also brings into question natural resources and land use. further to this, derived from the first international geomorphological conference held in manchester, uk, was environmental and dynamic geomorphology: case studies in hungary edited by pécsi (1985), which portrayed environmental geomorphology in hungary. most recently, zeitschrift für geomorphologie published the proceedings of the second international conference on geomorphology: geomorphology and geoecology held in frankfurt am main, germany in 1989 and included perspectives of environmental geomorphology by coates (1990). there have also been journal articles published as part of environmental geomorphology in various different languages. the natural sciences journal of hunan normal university published a paper in chinese by deng (1986) that placed the role of environmental geomorphology (along with regional and applied geomorphology) as a practical approach to territorial adjustment. the boletim de geografia teoretica published a paper by de barros goes (1988) in portuguese that was an application of environmental geomorphology at rio de janeiro. timofeev (1991) examined the object, aims, and tasks of environmental geomorphology in an article published in geomorfologiya in russian. the author approached environmental geomorphology as a new trend in science at the interface between geomorphic systems and human ecology. zeitschrift für geomorphologie, supplementband published an article by pécsi (1993) on environmental geomorphology in hungary, which advocated that this new research trend was born of practical topographic assessments (similar to the earlier practical approach to territorial adjustment by deng, 1986). importantly, he delineated the subject and goals of environmental geomorphology as different from geomorphology at large because of its focus on the consequences of human intervention, as in the development, change, and state of landforms from a practical perspective. sbornik ceske geograficke spolecnosti published a paper by ivan (1993) in czech that considered the cultural landscape and discussed environmental geomorphology as comprising research problems associated with cultural and disturbed landscapes. 12 thornbush (2013) there is a lack of theoretical development in environmental geomorphology in more recent years. for this reason perhaps, some studies do not claim to be a part of this subdiscipline even though the work is essentially environmental geomorphological in scope. for instance, martín duque et al. (1998) performed a landscape reclamation study representative of environmental geomorphology; however, the authors do not refer to environmental geomorphological explicitly within the article outside of the keywords. they did, however, instigate a methodological application. more recently, environmental geology approached hazardous wastes from an environmental geomorphological approach, arguing that environmental geomorphology normally lacks detailed environmental impact assessment (yesilnacar and cetin, 2008). these authors also presented a predominantly methodological study that is typical of environmental geomorphological research, with its emphasis on the development of methodology over theory. finally, mahaney (2012) most recently examined the implications of extreme heating events for an environmental geomorphology in a paper published by geomorphology. this paper similarly focussed on a methodological approach based on rock weathering in a geological investigation that was esse ntially driven by material testing (methodology, as through the use of scanning electron microscopy or sem) rather than aimed at a greater theoretical framework. nevertheless, another paper published recently by garcia et al. (2012) based a study of the dam rio verde-parana in brazil on an environmental geomorphology, with its aims reflecting concepts within the subfield, including the identification of both its environmental compartments as well as regional geology and physiography and human impacts in the area. these authors discovered an intense human influence, such as of urban growth, natural hazards (including mass movements and flooding), and a fragility of the landscape created by agricultural land use. perhaps the most unifying principle of environmental geomorphology is its emphasis on the practical use of geomorphology in order to solve problems associated with surficial processes and materials that may appear as landforms. as part of an applied geomorphology, environmental geomorphology could also abide by the principles and practice of an applied geography, as outlined by briggs (1981) as part of a problem-orientated discipline. specific problems identified by the author include: ‘...pollution, damage to wildlife, destruction of habitats, soil erosion and resource depletion; the problems of human deprivation and inequality’. in this way, he conveyed problems associated with both natural (physical) and cultural (human) landscapes (see fig. 1). moreover, his article has a more developed section on the method of applied geography than when addressing the subject matter of applied geography, which is similar to other published studies relevant to the subdiscipline. panizza (1996), for instance, differentiated a model of the geomorphological environment and humans (with active and passive branches), affecting impact and risk (refer to his fig. 1). this practical subdisciplinary approach often targets human-environment relations and is apparent in several recent studies in the literature. for example, a geoarchaeological study of australia considered past human-environment interactions, focussing on influences of human behaviour as distinguished from environmental impacts on key topics (holdaway and fanning, 2010). ‘human-made landforms’ are referred to in terms of human-environmental interactions in mountain regions, including the sudetes mountains, poland (latocha, 2009). these (human-made landforms), comprising more persistent types in the landscape, for example agricultural terraces, as well as disappearing anthropogenic features, such as field roads, are differentiated from natural landforms (latocha, 2007). other authors have developed a history of human-environment interactions (in the late holocene), noting some important (anthropogenic) events, such as the onset of agriculture in the yame’ river valley on the bandiagara plateau of dogon country, ounjougou mali, and the increasing role of human-set fires and food production (ozainne et al., 2009). since hydrology affects the livelihoods of rural communities and is an integral variable affecting desertification (huber-sannwald et al., 2006), rivers have received much attention within an environmental geomorphology; as for example, tracking the evolution of the yellow river in china in consideration of the physical components of the landscape (geological structure, climate) in addition to the human environment (li et al., 2003). such human-environment interactions have been regarded as relevant for study by natural scientists and are used to diagnose social and cultural change (rapp and jing, 2011). human land use has been central to approaches advocating human-environment interactions in conjunction with process geomorphology (e.g. enters et al., 2008), many stipulating sustainable land use (e.g. assessments of natural versus ecoenvironmental vulnerability, as in the apodi estuarine in northeast brazil; boori and amaro, 2010, 2011). the purpose of this study is to present (known) published works for oxford stone in order to develop a discussion of this research that has implications for conservation policy and practice. the overarching aim is to delineate the different works in order to arrive at a current understanding of this record of historical buildings in the context of environmental geomorphological studies. specific objectives are to review scientific research by various authors who have made a contribution over the years to studies of oxford stone, and discuss the future of oxford’s historical buildings. this paper outlines the state of the art and critically discusses directions taken in science and technology and its implications for stone conservation policy and practice. ultimately, this is a contribution to the literature in environmental geomorphology by placing studies of oxford stone as part of an applied geomorphology within the specific jurisdiction of environmental geomorphology (as denoted in fig. 1), as part of cultural landscapes within a more human facet of the subdiscipline that engages with the conservation of cultural landforms and landscapes. studies of oxford stone as a contribution to environmental geomorphology 13 oxford stone the published book by arkell (1947) oxford stone made the first significant contribution to an understanding of the variety of limestones comprising oxford’s historical buildings. his geological perspective is captured in this book, with much emphasis on the different types of limestones and where they were quarried, except for the final chapter on the decay, repair and maintenance of oxford buildings, where he focussed more on the condition of buildings during his time. in his chapter 8, arkell (1947) made several observations about oxford stone, which he accounted was transformed due to much refacing in bath and clipsham stones. for instance, bath stone needed replacement every 200 years, with large-scale renewal occurring in 1850-1860 at various colleges, including queen’s, exeter, jesus, all souls, and balliol colleges. the majority of restorations occurred in 1900-1912 with the introduction of clipsham stone, a durable variety of stone. buildings were observed to be thickly covered with ivy and creeper, such as magdalen (cloisters), exeter (quadrangle), and balliol (west front) colleges until some 20 years before the publication of his book, with christ church (meadow buildings) being loaded with greenery still in his time. then, some buildings still retained some of their original stone, where stone decay could be studied at the sheldonian theatre, radcliffe camera, bodleian (lower stages), christ church (library, canterbury quad and gate), trinity (chapel), pembroke (chapel), worcester, corpus christi (fellows building), and the old observatory. elsewhere, arkell (1947) noted that buildings had been modified through patching, scraping and even the use of preservatives. in his chapter, arkell (1947) considered the various weathering processes and features evident then, including encrustation, blistering and exfoliation; warts; ca vernous decay; weathering along bedding planes and granular disintegration; solution of the fine matrix as well as chemical decay along contacts (of limestone with sandstone); fracturing due to the use of iron cramps and dowels; vibration from road traffic on high street; creepers as well as lichens and algae; and last is his address of the future of oxford stone. his observations on the weathering of buildings were to become the basis of geomorphological research. he observed that crusts commonly developed on oxford stone, and that this was the most serious type of weathering, particularly for headington freestone that appeared in oxford in 1885. the formation of these skins developed through the accumulation of gypsum (calcium sulphate) from smoke released in the burning of coal. arkell (1947) described it as follows: ‘the surface of this [headington free-] stone on exposure to the weather forms a hard, impermeable, black crust and the skin curls up and peels off. in time a new skin begins to form and the process is repeated’. viles (1993a) delineated a three-stage conceptual model of blistering, which concurs with his observations. moreover, a study on the environmental pollution of oxford confirmed that restorations were frequent when colleges were burning sulphurous coal transported by way of the oxford canal (viles, 1996a). the outline by arkell (1947) of skin formation is as follows: the blistering of the skin, with formation of an empty cavity behind it, seems to be due to the fact that the calcium sulphate skin has different physical properties from the stone (calcium carbonate) behind it and so reacts independently to changes of temperature and moisture, until eventually it parts company. in particular the skin expands more than the stone when heated by the [s]un, and the blistering is a natural response to the conflict of forces so set up. studies of temperature in the formation and exfoliation of skins have been mostly neglected for oxford apart from a study by viles, (1993b), who examined the impact of orientation on weathering features like blistering (on south-facing walls). moisture through walls (but not oxford fogs or drizzle in the making of sulphuric acid) was examined by sass and viles (2010a), who found more moisture in locations of decay, such as under blackened crusts. experiments using simulated driving rain showed that weathered blocks absorb more water and this occurs at a faster rate than by crusted or replacement blocks (sass and viles, 2010b). however, they reported that these decayed blocks also dried up faster than other blocks. temperature may be an important variable that has not received as much attention as it perhaps should, especially since arkell (1947) noted that blistering was worse on south walls that receive more daytime sunlight (and experience the most temperature changes); as for example, any headington freestone still remaining in the bodleian quadrangle. where moisture is not the culprit, irregularities in stone hardness (as well as any nodular structure) could lead to cavernous decay, which could develop to a depth of several inches. goudie and viles (1997) published a book on salt weathering hazards that addressed the occurrence of salt weathering, which has been known to include cavernous weathering. more work, however, could be done field-testing for stone hardness in order to account for the ribs or ‘bars’ that arkell (1947) outlined as part of the ‘toning down’ process in addition to cavernous weathering. he also mentioned the mechanical etching of wind-driven rain and hail, which was examined in a study of soiling and rainwashing due to wind-driven rain from the southwest along the south side of the ashmolean museum by thornbush (2010a). this was not, however, directly on etching or at jesus college, where damage was attributed by arkell (1947) to acidity enhanced by organic matter from the covered market. he addressed rising capillary from the water table, which affected the base of columns, as on the south side of the clarendon buildings. he did refer to capillary action into sandstone, which has a greater porosity than limestone, leading to the enhanced decay of sandstone along limestonesandstone contacts, as evident on the plinth of the ashmolean museum. porosity may also increase as stones decay. it would have been helpful to address the role that condensate (settling close to ground-level in a cold, humid location) will have on the weathering of limestone. 14 thornbush (2013) studies have not followed up on some areas addressed in the book by arkell (1947). some have already been outlined, but others remain to be mentioned. for example, research has not addressed the excessive use of iron cramps and dowels to emplace bath stone, which led to fracturing and spalling of the stone. even though much research has addressed the impacts of traffic pollution due to the oxford transport strategy and its monitoring (e.g. viles, 1996b), the impact of traffic on vibrations, especially along busy streets like the high street, has not been investigated. arkell (1947) presented a study conducted in 1932 at university college to monitor vibrations on the high street using a milne-shaw seismograph. it would be interesting to revisit this research and follow-up in order to test for any weathering features more predominant where there are more vibrations from traffic, such as cracks due to structural instability and damage. in his final book chapter, arkell (1947) addressed several biota, including creepers, lichens and algae. in his time, it appears that there was some hostility towards ivy and creepers, and their use was highly controversial. there is no doubt that this controversy continues today, when organisations like english heritage are struggling with whether ivy should be carefully managed and have invested in research into their bioprotective versus biodeteriorative impacts. arkell (1947) took the stance that creepers should be kept away from already weathered buildings, such as those experiencing crumbling and/or exfoliation. his concern was that the mechanical action of creepers, ivy in particular, will hasten the weathering process. for example, even the wind can pull them and move them about, potentially contributing to damage when these climbing plants pull material. however, he was of the opinion that sound buildings could withstand the use of ivy and creepers, assuming that the plants’ growth is controlled (e.g. away from windows and eaves and not allowed onto roofs). he identified some advantages to such climbers, which included their ability to hold moisture to the wall and keep it damp (this could, however, evoke chemical weathering). this was also recently supported by sternberg et al. (2011), who found higher relative humidity on ivy-covered walls relative to uncovered (exposed) walls. arkell (1947) also observed that the leaves of these plants act like tiles, shedding off water, which offers walls some protection from rainwashing. the only similar line of research to test this latter observation was also by sternberg et al. (2010), who advocated that ivy also protects walls from the deposition of dust particulate due to shielding by leaves. however, they did not address deleterious impacts that arkell (1947) mentioned, for instance that the tendrils and suckers can secrete acids enhancing decay. he described that these tendrils and suckers become attached to walls and coat them with a hard woody substance, which is visible when the plant is removed. this was observed by arkell (1947) at exeter and lincoln colleges, where he attributed it to the clearance of ampelopis. he did seem to favour the greenery produced by such plants, suggesting that they improved the aesthetics of buildings, particularly those without perfect symmetry and masonry. he valued the use of controlled creepers like at lincoln and pembroke colleges, and found that the plants made these places more pleasant, especially in the summer. for example, amepolopsis growing at new college is green in the summer, but turns crimson in the autumn. his concluding view, however, was that research should focus on testing for the harmfulness of ivy and creepers, for instance as was evident at lincoln college, in places previously occupied by creeper that were subsequently decayed, with creeper as a possible cause. in this latter case, arkell (1947) suggested keeping the wall clear of creeper. nevertheless, he did believe that flowering plants, like wistaria, should be allowed to grow on plain walls, even if harmful. his view of lichens and algae, on the other hand, was that they offered a protective covering and showed no sign of harm to the stone. this latter point is also a point of contention in the literature on biodeterioration. other studies many publications have followed the classic volume by arkell (1947), most of it linked to work by viles driven by some funded research projects. the first of these projects concerned the environmental monitoring of the oxford transport strategy of june 1999 (viles, 1996b). here, the concern was over the impact of air pollution on oxford stone due to traffic. this project involved three strands of research, including exposure trials and photographic monitoring of walls. sensors exposed at roadside locations were examined by viles and gorbushina (2003) after up to three years of exposure. they found that sensors located on busier roads became soiled faster; that all sites experienced bacterial, fungal (especially within surface hollows) and phototropic colonisation (particularly at a background site that had higher colonisation of organisms after just three years), included particulate matter deposits, and also conveyed calcite dissolution. these findings led to a detailed study of fungi on these oolitic stone sensor samples (thornbush and viles, 2006a). for the second strand of the project, photographic surveys were extended from 1997 to 2003 to encompass six years of monitoring (thornbush and viles, 2008). this photographic survey involved an integrated qualitative-quantitative approach; however, other studies quantitatively assessed soiling and decay of the building stone (e.g., thornbush, 2008a). participation in a newly funded project on catastrophic decay in building limestones led to more published work on oxford’s oolitic limestones. when smith and viles (2006) compared limestone with sandstone building stone, they discovered a patchiness and contagiousness in the former that was connected to catastrophic decay. gomez-heras et al. (2010) more recently published a paper on ‘oxford stone revisited’ in the fashion of arkell (1947) that examined the diversity of building limestone in the historical buildings. most recently, english heritage funded a project ivy on walls that generated some research into the bioprotective versus biodeteriorative effect of keeping ivy, in particular, on walls. two studies by sternberg et al. (2010, 2011) studies of oxford stone as a contribution to environmental geomorphology 15 were already mentioned, but some work was also performed by thornbush (2008b, 2012a) based on photoarchival searches in college archives, including at trinity and pembroke colleges. some studies have presented new methods or approaches for use on oxford stone. soiling was examined at various scales from stone sensors exposed during the environmental monitoring of the oxford transport strategy using the integrated digital photography and image processing (idip) method by thornbush and viles, (2004a, b) to entire blocks on the boundary wall of worcester college with the decay mapping in adobe photoshop (dmap) approach developed by thornbush and viles (2007a). a novel technical approach was taken with the application of portable x-ray fluorescence to the same wall (2006b), finding high levels of iron on newly replaced stone blocks that possibly conveyed weathering through iron migration to the stone surface (rather than iron deposits). an earlier study by inkpen et al. (2001) used geographic information systems (gis) to map decay derived from a time sequence based on old photographs taken of oxford stone. later, inkpen et al. (2008) presented an integrated database and gis that was used to record and monitor oxford stone degradation. sun et al. (2010) designed a new optical fibre humidity sensor for monitoring building stone deterioration. discussion and conclusion much has been learned about the soiling and decay of oxford stone. even though arkell (1947) did not systematically test his observations, making only qualitative judgements of stone weathering in his final chapter, what he did observe has been generally supported by scientific research. however, not all of his observations have been tested, for instance algal cover is still not yet addressed in the published literature for oxford, except for a quantitative study by thornbush (in press b). lichens have been examined through rooftop experiments in oxford by carter (2002) and carter and viles (2003). more research needs to be conducted with aspect (wall orientation) in mind, which will affect microclimate (temperature in particular) and the development of lichens and algae. (thornbush is currently working on a lichen study that quantifies lichen distribution across a string course in the oxford city centre, where she considers microclimatic effects, including aspect). further microclimatic studies are still needed to examine the weathering features found on historical buildings in central oxford. the use of a climatic chamber (as by thornbush and viles (2007b), who tested for the dissolution of weathered versus unweathered surfaces in differently concentrated solutions of carbonic acid) would be ideal for this kind of work in order to support any field experiments. temperature, as well as moisture, variations should be considered in these studies. needless to say, more research is needed to address any potential harmful effects of ivy on walls, including physicochemical analyses that test for chemical secretions and their acidity. this is relevant because decaying plant matter also generates acids that could be harmful to oxford stone even in nonacidic (clean) air. this is considered in detail by thornbush (in press c) in a recent publication that addresses the biodegradation and biodeterioration of limestone surfaces covered with vegetation (climbing plants in particular). more attention to the archival record for past use may be beneficial to understanding the use of climbing plants at oxford colleges, including case studies at christ church, exeter, and lincoln colleges. it is also relevant to investigate the different impacts of evergreen (ivy) versus deciduous (creeper) varieties. this would provide a cross-temporal context similar to the study by thornbush (2010b), which reexamined a selection of buildings included in restoration photographs taken by the oxford historic buildings fund between 1957 and 1974. more recently, thornbush (2012b) has devised a simple photo-based weathering index, namely the s-e index, for classifying soiling and decay damage to historical limestone based on a laneway in central oxford, where a majority of buildings have not been cleaned or refaced in recent years. this classification system takes into account physical, chemical, and biological weathering processes and is based on the quantification of visible weathering forms. it has been applied most recently at churchyards located centrally in oxford by thornbush and thornbush (in press a). the conceptual framework for this paper is based on environmental studies performed in urban environments. they have encompassed studies employing a variety of both quantitative and qualitative methods, as outlined in table 1. moreover, these studies within an environmental geomorphology address both human and natural (physical) landscapes as well as human-environment relations. topics have included land use (urbanisation, conservation); pollution (from energy production, such as from coal fires and transport); and microclimate (temperature, moisture). these main themes have, respectively, produced works addressing vegetation cover; acid rain; and aspect. perhaps one of the greatest contributions of the current research is its use of photography. such a photogeomorphological approach taken initially by viles (e.g. 1994) in her photographic monitoring and taken up and developed by m.j. thornbush since 2004, is an advantage because of its contribution to an expanding photographic record, which could be used cross-temporally by various workers to develop new methods to examine the degradation and deterioration of oxford stone. some oxford colleges also house extensive archives that could help extend the temporal photogeomorphological record back to the middle of the 19th century. these enable longer term studies that examine the visual appearance of oxford stone, including any weathering features (especially if visible close-up). for example, as in the cross-temporal study of traffic congestion and stone decay that was conducted using archival material (including photoarchival) at magdalen college (thornbush and viles, 2005). 16 thornbush (2013) thornbush and thornbush (in press b) are currently working on a book entitled photographs across time that portrays physical and cultural landscape change in urban settings, including oxford, in a rephotographic approach. another major contribution of these studies is as exemplar of environmental geomorphology within an applied geomorphology in the realm of heritage science conservation. since this geomorphology subfield has already been delineated in earlier works (such as panizza (1996) in an introduction to environmental geomorphology), the current review encapsulates oxford stone as part of this applied geomorphology, providing a further case study to supplement the published hungarian case studies. the current case study also aligns well with the multidisciplinary approach comprising geomorphic systems and human ecology outlined by timofeev (1991), as well as the emphasis on cultural landscape advocated by ivan (1993). it also supports recent frameworks developed by the author (thornbush, 2012c), who recently outlined the inclusion of archaeogeomorphology as a subfield of an applied geomorphology that examines cultural landscapes. environmental geomorphology would encompass archaeogeomorpholgoy, and cultural landscapes with a human-oriented geomorphology (in addition to more traditional (physical) landscape geomorphology), and would in turn be an applied (practical) geomorphology (see fig. 1). more specifically, as denoted by several other authors (fisher, 1984; pécsi, 1985, 1993) environmental geomorphology is a practical (applied) geomorphology. as such, for oxford, it provides a framework for studies in the degeneration of the (built) environment (prasad et al., 1984). it also encapsulates practical problems of utilising the environment in these urban settings conveyed by pécsi (1986) and the consideration given by coates (1990), conveying environmental geomorphologists as scientists who are concerned with solving societal problems, including where natural surface processes have affected the built environment (installations and properties) as well as where they are changed by human activity, such as the the deterioration of oxford stone through (among other reasons) exposure in a polluted environment due to combustion. this paper does not consider either the variety of limestones used in oxford’s historical buildings, nor does it consider methods of repair and maintenance in any detail. however, it does pick up on the discussion by arkell (1947) of the future. at the end of his chapter 8, he conveyed that in the past oxford colleges employed their own masons, but that the trend now is to contract out the work. in his time, only magdalen, wadham, and exeter colleges still employed their own mason. today, however, some colleges do keep clerks-for-works or architects. the problem of keeping the latter, however, is that architects are not necessarily stone conservation experts. arkell (1947) recognised oxford’s historical buildings as a national heritage, which should be upheld by an advisory panel: for that same fellow will readily agree that oxford is a national heritage. and if the university as a whole is a national heritage so are the individual buildings that compose it. the university, acting through its advisory panel of architects, university officers, scientific experts, and chosen representatives of the colleges, would seem none too large an authority to take responsibility for the components of such a heritage. the office of the panel would have many responsibilities, including reporting to the government building research station. he suggested that the panel obtain its own portable cleaning outfit that would be made available for regular cleaning and treatment of buildings that could promote regular inspections of decay and keep an up-totable 1 methods used in oxford studies method chronology of references vibrations (seismograph) bowen in arkell (1947) field surveys viles (1993b); smith and viles (2006); thornbush (in press c); thornbush and viles (2008) exposure trials viles (1996b); carter (2002); carter and viles (2003) mapping and gis inkpen et al. (2001, 2008) scanning electron microscopy (sem) thornbush and viles (2006a); viles and gorbushina (2003) portable x-ray fluorescence (pxrf) thornbush and viles (2006b) simulation experiments thornbush and viles (2007b) computer processing thornbush (2008a, 2010a, in press b); thornbush and viles (2004a, 2004b, 2007a) archival studies thornbush (2008b, 2012a); thornbush and viles (2005); viles (1996a) petrographic analysis gomez-heras et al. (2010) 2-d resistivity surveys sass and viles (2010a, 2010b) ibuttons sternberg et al. (2010; 2011) optical fibre humidity sensors sun et al. (2010) (re)photographic surveys thornbush (2010b, 2012b, a); thornbush and thornbush (in press a, in press b); viles (1993a, 1994) studies of oxford stone as a contribution to environmental geomorphology 17 date dossier of each building. however, to the author’s knowledge, an advisory panel is still missing from the university’s administration, which could, as arkell (1947) suggested, help to bring together different experts and supports within the university, including individual colleges and schools (including laboratories). the current practice of conserving oxford stone requires the replacement of blocks that have suffered from cavernous weathering (blowouts) once crusts have been breached and the more friable material beneath collapses. this was evident relatively recently after cleaning at various locations, such as at the boundary wall surrounding magdalen college along longwall street in central oxford. cleaning of the stonework does reveal decay features, such as is still evident on the plinth of the ashmolean museum even after it was restored recently. although cleaning brightens the stonework, it does not conceal stone decay damage, which can only be patched-up or replaced. for example, replacement blocks are still evident at the boundary wall of worcester college, although they are now darkening and less conspicuous. outside exeter college facing onto turl street, blocks have been (noticeably) replaced on the façade. the sheldonian emperors’ heads are another example of replaced oxford stone that brings into question the authenticity of the fabric of oxford’s historical buildings. cleaning and restoration works are performed piecemeal by storey, as is evident recently at the bodleian library, whose upper storey was restored recently and the middle level cleaned. this practice (of piecemeal cleaning and replacement) makes it difficult to perform temporal studies of stone decay for oxford’s historical buildings. it is also difficult to control the lithology of the type of limestone used even across one façade, as for example at the ashmolean museum, which comprises different varieties of limestone in addition to sandstone. oxford’s buildings are often hidden behind scaffolding, which has become an expected part of this urbanscape. its historical buildings are now a mere cast of what they once were because of various ‘face-lifts’ over the years, including since the time of arkell (1947). even though stone decay has been studied and tested, science cannot solve the problem of oxford stone’s plight with time. this takes one back to the beginnings of environmental geomorphology and specifically the original work by coates (1971), with its portrayal of this geomorphology subfield as being conjunctant to landscape conservation. moreover, the work by prasad et al. (1984) addressed the degeneration of environment, which suits this examination of studies of oxford stone. the historical buildings of central oxford are part of a cultural landscape that needs to be conserved and as a cultural heritage resource that needs to be sustained. by examining how cultural stoneworks change due to exposure in certain environments, such as in polluted urban settings, it is possible to work towards their conservation rather than piecemeal replacement and replication. these studies make a contribution to environmental geomorphology as cultural heritage that is susceptible to (passive) human activities that enhance an area’s vulnerability (panizza, 1996), leading to risks associated with the conservation of this cultural landscape and affecting the sustainability of this resource. by examining human-environment relations within environmental geomorphology, it is possible to better connect the human (cultural) and physical (natural) branches of the environment. this includes considerations of human landforms, as in a built-up urban setting in the current study, rather than just traditional notions of physical landforms previously addressed by geomorphologists. references arkell, w.j. 1947. oxford stone. london: faber and faber limited boori, m.s., amaro, v.e. 2010. detecting and understanding drivers of natural and eco-environmental vulnerability due to hydro geophysical parameters, ecosystem and land use change through multispectral satellite data sets in apodi estuarine, northeast brazil. international journal of environmental sciences 1 (4), 543–557. boori, m.s., amaro, v.e. 2011. a remote sensing approach for vulnerability and environmental change in apodi valley region, northeast brazil. world academy of science, engineering and technology 50, 501–511. briggs, d.j. 1981. the principles and practice of applied geography. applied geography 1 (1), 1–8. carter, n.e.a. 2002. bioprotection explored: lichens on limestone. unpublished doctoral thesis. oxford: school of geography and the environment, university of oxford carter, n.e.a.,viles h.a. 2003. experimental investigations into the interactions between moisture, rock surface temperatures and an epilithic lichen cover in the bioprotection of lichen. building and environment 38, 1225–1234. coates, d.r. 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(ed.) proceedings of the 8th international congress on deterioration and conservation of stone, 30 september-4 october 1996, berlin, 831–834. viles, h.a., gorbushina, a.a. 2003. soiling and microbial colonisation on urban roadside limestone: a three year study in oxford, england. building and environment 38 (9-10), 217–1224. yesilnacar, m.u., cetin, h. 2008. an environmental geomorphologic approach to site selection for hazardous wastes. environmental geology 55 (8), 1659–1671. journal of environmental geography journal of environmental geography 6 (3–4), 1–11. doi: 10.2478/jengeo-2013-0001 issn: 2060-467x 14 th -16 th -century danube floods and long-term water-level changes in archaeological and sedimentary evidence in the western and central carpathian basin: an overview with documentary comparison andrea kiss 1,2* , józsef laszlovszky 3 1 institute of hydraulic engineering and water resources management, vienna university of technology, karsplatz 13, 1040 vienna, austria 2 department of physical geography and geoinformatics, department of historical auxiliary science, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 3 department of medieval studies, central european university, nádor u. 9, h-1051 budapest, hungary *corresponding author, e-mail: kiss@hydro.tuwien.ac.at research article, received 25 march 2013, accepted 4 june 2013 abstract in the present paper an overview of published and unpublished results of archaeological and sedimentary investigations, predominantly reflect on 14 th -16 th -century changes, are provided and evidence compared to documentary information on flood events and long-term changes. long-term changes in flood behaviour (e.g. frequency, intensity, seasonality) and average water-level conditions had long-term detectable impacts on sedimentation and fluvio-morphological processes. moreover, the available archaeological evidence might also provide information on the reaction of the society, in the form of changes in settlement organisation, building structures and processes. at present, information is mainly available concerning the 16 th , and partly to the 14 th -15 th centuries. these results were compared to the available documentary evidence on 14 th -16 th century danube floods occurred in the carpathian basin. keywords: danube, floods, high flood-frequency periods, 14 th -16 th century, sedimentary and archaeological evidence, carpathian basin introduction the 16 th century has key importance in studying and understanding medieval and early modern danube floods. it is due to the fact that a great number of large and extraordinary flood events are known from the early, and then from the mid and late 16 th century which caused severe damages along several central european rivers (for the last systematic overview, see brázdil et al., 1999; for extraordinary 16 th -century floods in austria, see: rohr, 2007), including the danube. due to the fact that recently a first systematic overview of documentary evidence on 14 th -16 th -century danube floods in the carpathian basin has become mainly available in publications (for 11 th -15 th century evidence: kiss, 2012a, 16 th -century: kiss, 2012b; kiss and laszlovszky, 2013; partly related vadas, 2011), it is possible not only to list and discuss sedimentary and archaeological evidence on flood events, but also to find some connections and provide links between the different types of floodand high water-level related evidence. the results of archaeological and sedimentary investigations are in good agreement with the information detectable in documentary evidence: the presently available material presumably highlights most of the great flood events of extraordinary magnitude and the most important flood waves. documentary evidence is mainly related to individual flood events or the relatively short-term consequences of preceding great flood events and therefore mainly provides high-frequency information. archaeological and sedimentary evidence is mainly connected to the consequences of great or catastrophic flood events, flood-rich periods and long-term hydrological changes. since dating of these events, periods and processes, with using natural scientific and archaeological methods, are usually possible on a multi-annual, multidecadal level, archaeological and sedimentary data on floods are good indicators of mediumand lowfrequency changes in flood behaviour. nevertheless, documentary evidence can provide an important help in the possible more exact dating of flood events or flood peaks whose impacts could be observed in archaeological (and sedimentary) evidence (for presently available data, see: fig. 1). beyond the application of documentary evidence, with the help of archaeological and sedimentary evidence the magnitude, long-term impacts and (materi2 kiss and laszlovszky (2013) al) consequences of great flood events as well as ge neral long-term processes can be further studied in more detail. in the present paper the published materials and scientific literature on findings in the marchfeld and the bratislava-žitný ostrov area (šamorín), the danube bend (nagymaros, visegrád, vác), budapest (margit island) either as a source for further investigation (e.g. dinnyés et al., 1993) or with further environmental interpretations (e.g. mészáros and serlegi, 2011) are discussed, and possible connections with documentary evidence are provided. moreover, unpublished primary results of archaeological excavations, excavation protocols, for example, that of the visegrád franciscan friary are also included in the present survey. most of the archaeological and sedimentary evidence is related to the 16th century: however, most of the processes have started already in the 14 th and 15 th centuries and therefore these two centuries also form an integrate part of the present discussion. available sedimentary-archaeological evidence: an overview of scientific investigations mid-16 th century: increased danube sedimentation at orth – parallel changes on the lower morava river? due to its immediate vicinity to bratislava, the available data on 15 th -16 th -century sedimentation conditions and changes of the danube has crucial importance in the further understanding of contemporary flood processes. the rapid 16 th -century silting-up process of a late medieval harbour, located in a fossil danube channel, was investigated and results recently published by fiebing and their colleagues (fiebig et al., 2009; thamó-bozsó et al., 2011). the study area is located south to the town of orth along the danube (at the sw edge of the marchfeld area, a former floodplain), and thus between vienna and bratislava (see fig. 2). based on the dendrochronology analysis, the wooden remains of the harbour were dated between the 14 th -16 th centuries. although some samples date back to the late 14th century (cutting date), most of the construction wood was cut off in the first half of the 16 th century (especially between the late 1520s and 1550; see fig. 6 in fiebig et al., 2009). 1550 was defined as a closing date of woods used in the construction of the harbour; the harbour was then covered by flood sediments. of course, it does not necessary mean that the harbour was immediately given up in 1550 sharp. nevertheless, the desertion of the harbour must have happened not much later. an interesting additional point is that the vienna town hospital accounts – which contains information on the danube floods disturbing or obstructing wood/timber transport – report on a danube flood in 1548 (wstla, bürgerspital bd. 26; for more source evidence and recent discussion on the consequences in vienna, see sonnlechner et al., 2013). referring to the age of the deposits (osl dating) and that of the wooden materials, the authors concluded that a rapid infill (increased sedimentation) of the river branch around the 15 th -16 th centuries resulted the sudden desertion of the harbour (thamó-bozsó et al., 2011). for possible reasons of this rapid infill the authors suggested either the natural process of meander development or the great forest clearances of the late medieval period. in our opinion, a most likely direct factor (for the infill, and in reaching the cut-off of the meander), one or more great danube floods or high flood frequency of the period, should be also listed among the main reasons of the rapid infill process of the harbour and the danube channel. applying early maps, similar changes from the second half of the 16 th -century were also mentioned by hydromorphologists, for example, concerning the cut of a danube meander at wolfsthal, probably preceded by a flood event or a series of events (pišút, 2005; pišút and tímár, 2009). the historian, sándor takáts (apart from several references on destructive mid and late 16 th century ice flows) also mentioned such a case, namely that a harbour and main toll place, dated from high medieval times, was moved away from its original location 0 1 2 3 4 1 3 0 0 1 3 1 0 1 3 2 0 1 3 3 0 1 3 4 0 1 3 5 0 1 3 6 0 1 3 7 0 1 3 8 0 1 3 9 0 1 4 0 0 1 4 1 0 1 4 2 0 1 4 3 0 1 4 4 0 1 4 5 0 1 4 6 0 1 4 7 0 1 4 8 0 1 4 9 0 1 5 0 0 1 5 1 0 1 5 2 0 1 5 3 0 1 5 4 0 1 5 5 0 1 5 6 0 1 5 7 0 1 5 8 0 1 5 9 0 1 6 0 0 great flood flood n u m b e r o f fl o o d e v e n ts ( p e r y e a r) r e p o rt e d 1503 1523 1574 15491426 14391416 1413 1568 13931346 1569 problems caused by previous floods (with year) fig. 1 14th-16th-century danube floods in the carpathian basin, based on presently available documentary evidence (sources: kiss, 2012a, 2012b; kiss and laszlovszky, 2013) (14th-)16th-century danube floods and long-term water-level changes in archaeological and sedimentary evidence in the west and central carpathian basin: an overview with documentary comparison 3 to komárom (from historical csicsó – today čičov in slovakia, in the žitný ostrov: see fig. 1) in the early 16 th century, and its harbour and foreground was filled up with danube flood sediments (takáts, 1898). as a possible parallel, described in an official letter in 1549, short before the danube at bratislava also partly changed its bed, and floods were actively damaging the town walls (see kiss, 1908; for more details see: kiss, 2012b). concerning this case, ortvay (1912) suggested that – similarly to the cases described by fieber and his colleagues at orth – an avulsion of the danube channel occured at bratislava, and made the town walls (which were anyway in bad condition) more prone to destructive flood events. it is quite probable that this later event had connections to the great 1548 flood in vienna mentioned above. moreover, a number of flood events were also reported in contemporary documentation concerning the 1550s, and the great floods occurred practically in each year around the turn of the 1560s and 1570s (see fig. 1). another important investigation on river sediments was carried out, practically in the same time, on the lower sections of the morava river, an important tributary of the danube, entering the river just before bratislava. according to the study, a substantial change occurred in the character of flood sedimentation (from clay-dominated layers to layers with more sandy and silty character) around 1550 (and/or the decades around). prior to this date, the authors also detected another period of increased fluvial activity which, based on the flood catastrophe and its hydromorphological consequences, reconstructed by bork (1989), they connected to the 14th-century period and the 1342 flood event (kadlec et al., 2009). in another study concerning the same area it was concluded that two most important changes in river channel structure occurred in the 13 th century and in the second half of the 16 th century (1550-1600; see grygar et al., 2011). an interesting additional information might be that, according to takáts (1898), in 1573 the morava river left its bed at ungernsdorf; because of this change, the mills of marchegg could not be used any more. since the morava river collects the waters in the moravian basin, and then enters the danube close to bratislava, parallel processes, occurred in the 16th century (especially in the mid 16 th century) suggest large-scale changes in the flood behaviour of the river. moreover, it also suggests that these processes, namely the high flood frequency on the river morava in the second half of the 16th century, could be detected approximately in the same time on the danube close to bratislava (most data in fig. 1 is originated from the bratislava area; see kiss 2012b) and on its important tributary. based on documentary evidence, this mid and late 16 th -century flood peak was also detected on both the german (e.g. lech, isar, partly the inn; see böhm-wetzel, 2006) and the austrian tributaries of the danube, and also on the upper danube itself (traun: rohr, 2006; danube: rohr, 2007; glaser, 2008; sonnlechner et al., 2013). it is an interesting, additional information that the importance of the mid and late 16 th century in studying historical soil erosion caused by water has not yet been detected in germany (including southern germany). according to the authors of the latest overview, from the high medieval period onwards, only two weak maxima could be traced: one around 1200-1400, with special emphasis on the disastrous 14 th -century events culminating around 1342, and another around 2-3 centuries ago, with special emphasis on the late 18 th -early 19 th century. these interim results, however, might underestimate soil erosion intensity in the medieval and early modernmodern period, due to the low number of dated colluvial layers (see dreibrodt et al., 2010). fig. 2 locations mentioned in the present paper 4 kiss and laszlovszky (2013) (14 th -)16 th -century changes in šamorín: a prosperous town in dangerous location? in the late medieval town of šamorín (historical somorja; see fig. 2) in the žitný ostrov (historical csallóköz; island area east to bratislava, in south-slovakia) two main building periods were distinguished by archaeological excavations (urminský, 2005). one of them took place after the destruction of the high medieval wooden structures (in a flood-risk area of danube branches) in the second half of the 14 th century when, together with a change in building material from the wooden-clay structure to brick (at least at the foundations), in the yards of houses (located on a slope descending from the loess terrain) along the main street of the settlement a 0.5 m ground-level rise could be detected. another turning point occurred around the end of the 15 th and beginning of the 16 th century. on the main street of the town (fő utca) new building process was started: in this case the feature of the yards was 'radically' changed: the ground level of the yards was raised with around 1.5 m. as a documentary parallel, mainly based on the flood-related information preserved in the bratislava accounts a rather significant flood peak was detected in the late 15 th and early 16 th century (see fig. 1): starting from the end of the 1470s, in the decades of the 1480s, 1490s and 1500s great and destructive floods and ice flows (and ice floods) occurred at least in every other year, sometimes more than one within a year (e.g. 4 great floods in 1485; for detailed information on documentary evidence, see kiss and laszlovszky, 2013). this flood peak, otherwise, quite distinctively appears also on the flood frequency diagrams of the bavarian danube tributaries (see böhm and wetzel, 2006). due to their potential consequences, it is worth to refer to the greatest flood events in particular. in austria, including the vienna area, the "deluge" in 1501 (august) was the largest reported flood event on the danube; it was estimated to be significantly larger than the great flood event of 2002 (e.g. rohr, 2007; http://www.wien.gv.at), or the ones occurred in 1899 and 1954 (kresser, 1957). concerning the carpathian basin, a rather clear source refers to this flood event: the inhabitants of vámos(szabadi – see fig. 1) in the szigetköz island area, close to győr (thus, southeast to šamorín, on the opposite side of the danube), were allowed to pay half of the tax due on saint george's day (24 april) in 1502 because of their need/poorness caused by the "deluge" ("dilu(v)ium aque"; source: hna df 279560). it seems, however, that a significant flood event already occurred on the danube at bratislava earlier, in may; while some of the flood damages were reported in late october (hna df 240953, 277113). additionally, a royal charter provides a testimony that the problem of frequent floods caused severe, constant problems for the inhabitants of bratislava by 1503 (hna df 240970; see fig. 1). 1503 in itself is also interesting because, apart from 1501 and 1508, this was another major flood year on the danube tributaries (see e.g. rohr, 2007). the other great (double-)flood event in austria occurred in 1508. at the moment, information concerning the magnitude of the 1508 flood event in hungary is available only in indirect evidence: the flood mark of the 1508 flood event (although the newspapers refers to 1509) on a tower of the győr was still seen and compared to some 18th-century flood marks (1768-referred as 1769 and 1784), in which case the flood level of the 1508 event was above the maximum level of the other two, 18thcentury levels (see magyar hirmondó 27 march 1784, no. 24; kiss, 2012b). it is also an interesting question why the 1508 flood mark was reported and no any reference was mentioned on any possible 1501 flood mark. there is no direct evidence available whether or not these changes were connected to any flood problem. however, it is still an interesting fact that especially the second, 'drastic' ground-level rise occurred – parallel to the building processes and changes observed at the margit island and also in visegrád – exactly in the same period when the important late 15th–early 16th-century flood peak and the two catastrophic danube floods (1501, 1508 and perhaps also 1503) took place. thus, even if the new building process in šamorín could also accidentally occur in the same time when large danube flood events took place – for, example, elevation changes in ground level can be also detected along the danube in less flood endangered location (e.g. the resettling process of the village of csöt/csút at budafok-háros; see: irásné, 2004a and fig. 1) –, the destructive flood events might have had some impact on how the new ground levels, the settlement and building constructions developed. thus, it is an interesting coincidence or probably more than a mere coincidence that since the second half of the 14 th century (when otherwise the wooden structures were also destroyed) exactly around the turn of the 15 th –16 th centuries arrived the time when significant and extensive earthworks (great rise of ground level of the yards) were carried out. the question might have some further important aspects: šamorín is the interesting case which was mentioned in late medieval–early modern documentary evidence concerning early flood protection works. in this respect, both in 1426 and in 1569 the flood danger and damages affecting the town's cultivated lands (and also the entire žitný ostrov area) were mentioned as a chief problem and the main reason for large-scale flood protection works (kiss, 2012a,b). however, in these cases, either in the form of a direct royal order or a parliament decision, the damages and losses of the cultivated lands, and not the damages occurred in the town (i.e. buildings, inhabitants) were emphasised. it might also be an interesting parallel that, while a significant rise of ground level occurred in the yards, no elevation change of the main street and the ground level of houses took place around the turn of the 15 th and 16 th centuries. gravel-loess layer as a trace of major 16 th century flood(s)? nagymaros in the danube bend according to andrás pálóczi horváth, a great 16 th -century danube flood left a distinct gravel layer (mixed with loess) over the 15th–16th-century pottery and (early and late) 15 th century coins in the market town of nagymaros (opposite to visegrád), in a depth of 110 cm. regardless of which flood event or events caused this gravel-loess layer, it had to be a (14th-)16th-century danube floods and long-term water-level changes in archaeological and sedimentary evidence in the west and central carpathian basin: an overview with documentary comparison 5 major event or set of events: the appearance and large quantity (dominance) of gravel in the layer may suggest increased sediment-carrying capacity, which is typical for flood events with great discharge (see e.g. nagyváradi, 2004). moreover, due to the relatively high level of this significant river sediment, this flood event (or events) could be comparable in height to the great 20 th and early 21 st -century danube floods. above the gravel-loess layer, a mixed layer was found with 14 th –17 th -century remains (report published in: dinnyés et al., 1993). it has to be noted that the nagymaros side is the side where danube sediments (especially rough sediments) are predominantly settled down by the river (it is dependent on the geoand hydromorphological conditions, and did not fundamentally change up to the present times). thus, especially rough sediments of danube floods are much more likely to appear in the nagymaros area than at visegrád. as we will see later, several rather interesting features (e.g. fine sediments), presumably related to danube flood event(s), indeed were identified in visegrád. in case of nagymaros, the predominantly 15 th century archaeological evidence was found as a separate (undisturbed) layer under the gravel-loess layer, which indirectly suggests that the previous layer had enough time to settle down and the following flood event already could not significantly disturb this late medieval layer. moreover, taking other danube sedimentary flood investigations into account (e.g. the investigations at paks, see nagyváradi, 2004), the gravel-loess layer could develop after a single flood event, or as a result of not only one, but a series of flood events. as for dating the flood event, applying the parallel observations carried out in vác and with reference to climatic change, mészáros and serlegi suggested that the flood had to occur during the turkish occupation and thus, not before the mid-16th century (mészáros and serlegi, 2011). since a major flood period occurred on the danube in the second half of the 16 th century (see e.g. kiss, 2012b), it is possible that this flood layer developed around the mid or late 16th century. nevertheless, the archaeological dating of the layer located underneath the gravel-loess layer (and so as the mixed 14 th –17 th -century infill) in itself may also allow an earlier dating for the disastrous flood event(s): this/these could, for example, also happen in the middle of the century, or even before (i.e. 1501, 1508 or 1515, for example, cannot be excluded either). in documentary evidence, the mid 16th century is characterised by great flood event(s) before 1549 prior to 1549, the consequences of great flood event at bratislava. moreover, damaging floods, reported prior to 1555, were probably also mentioned at komárom together with 1557 and 1558 flood events at bratislava. then the flood series of the 1560s has to be considered: the great flood events, especially from 1567 (for austria, see rohr 2007), in the late 1560s (1568, 1569) and early 1570s (great flood events occurred almost every year: see kiss, 2012b) caused long-term, irreversible changes, for example, in the bratislava and žitný ostrov area (e.g. lands swept away, reported in 1574: maksay, 1959) and can be considered as floods of extraordinary magnitude (for destructions in austria and vienna, see: rohr, 2007; sonnlechner et al., 2013). moreover, based on documentary evidence, we have to consider another peak of frequent and great flood events in the late 16 th and the early 17 th century, detectable in the komárom area (see e.g. hna, uc 86: 10, király, 1890; for further overview, see: kiss, 2012b). long-term processes: rising danube water level at visegrád in the late medieval–early modern times a long-term process, affecting settlement and building conditions even in the late medieval–early modern period, was observed at the urban excavations of visegrád. here a clear water-level rise of the danube occurred between the 13th and the 16th centuries, first detected by miklós héjj. he also raised attention to large-scale human impact on the danube catchment area as a potential reason for increased rise of danube water levels. miklós héjj’s investigations of settlement development, based on the excavations of the medieval royal centre and civil town of visegrád, suggested a long-term rise of danube (high or flood) water levels (in its danube bend section) from the 13 th century onwards (héjj, 1988). as a consequence of this process, we have to consider that the (high or flood) level of the danube might have been lower in the middle ages than it is today (mészáros, 2006). additionally, due to the extensive excavations of the royal palace complex and the settlement itself, concerning the rise of ground levels in different periods, a more detailed analysis can be provided. visegrád town: late 15 th –early 16 th -century cellar infill due to floods even more specific flood-related evidence has been recently published referring to some of the urban excavation sites: located in the present-day school yard, under the 18 th -century features a 14 th -century building was excavated. the cellar of this late-medieval building was filled up at the end of the 15th or beginning of the 16th century, presumably due to flood problems. this theory of the excavating archaeologists was supported by the fine sediment (mud) layers settled by flood water, found in the same cellar underneath the artificial infill (kováts, 2013). the archaeological data on late 15 th –early 16 th century floods is in good agreement with the information detected in documentary evidence: one of the most important (and certainly best documented) medieval flood peaks took place exactly around the decades of the 1480s, 1490s and 1500s (see fig. 1). all in one? 14 th –16 th -century flood processes and the franciscan friary in visegrád excavations carried out in recent years at the site of the medieval franciscan friary (built in the 1420s), located close to the danube on a gentle slope, provide us with further evidence (buzás et al., 1995; laszlovszky, 2009, 2013). since some important parts of the excavation results are yet unpublished, and also due to the fact that in this case practically all the 14 th –16 th -century processes, described in other cases, could be detected, related infor6 kiss and laszlovszky (2013) mation on the excavation site and the identified processes are discussed here in more detail. in this case at least two (or three) different processes could be identified. one was the general rise of the ground levels, which process can be clearly detected from the 14 th century: the remains of the earlier settlement were located around two meters underneath the friary, but especially under the cloister built in the 1420s (during the late 14 th – early 15 th -century flood peak: kiss 2011; for great danube floods in the carpathian basin see fig. 1, and kiss, 2012a; for the eastern alpine region: rohr, 2007). when the friary was founded, a big (double-)cellar was built on the western (danube) side of the cloister: one under the kitchen and the other under the refenctury (fig. 3). in this case, in order to compensate the slope of the terrain, the builders raised the ground level. at the same time, the floor level of the previously mentioned double cellar was roughly the same as the floor level of the houses of the 14 th -century settlement, replaced by the building complex of the franciscan friary (laszlovszky, 2009, 2013). two re-building phases were also detected during the archaeological investigation of the friary. one of them took place during the matthias-period (1458-1490, with a building activity ca. 1470-80s), while the larger, almost total re-building of the complex happened during the first decade of the 16 th century. during this new building phase, another significant rise of the ground level was initiated, which can be clearly detected in the layers of the cloister garth and under the pavement of the cloister walk. already in this phase one of the two cellars in the western wing, under the newly constructed kitchen has been filled up with earth and a small new cellar was erected in the eastern wing of the cloister, close to the hill slope, behind the building complex (see fig. 3). the other process detected is related to the cellar under the refectory: during another early 16th-century building process the remaining cellar, located in the western, danube side of the friary under the refectory, was filled up and a new cellar was built on the opposite (eastern) side of the friary in a safer location, carved into the rock of the slope of the hill and far from the river. during the building process, in 1511 the franciscans received permission to use the stones of the saint george chapel in building the new tower of the friary (buzás et al., 1995). the re-building process must have been finished by may 1513, when the congregation of the observant province took place in the friary. one year later (may 1514) another congregation of the observant leaders took place in the friary: in this case with the task of electing the delegates who could go to assisi for the general chapter. the friary clearly had to be in 'good shape' in 1513 and 1514 when the important personalities arrived and stayed there for the congregations. the next important information is known from 1540: in this year, due to the siege of the lower (royal) castle, the friary was damaged, and then, after the turkish occupation, by 1544 the franciscans left the friary forever (buzás et al., 1995). nevertheless, some time between these two dates, namely between 1514 and 1540 something (serious) happened in the environment of the friary, because one part of the building, namely the northern cloister walk (with pavement, pillars, vaulting etc.; for location, see fig. 3) sank down with one meter, and because of this great change, the gothic vault of the corridor has collapsed. when rebuilt, no vaulted structure was constructed, but most probably a simple horizontal wooden ceiling was used to cover the northern corridor. the infill of the for fig. 3 layout of the excavated early 15 th -century franciscan friary in visegrád (14th-)16th-century danube floods and long-term water-level changes in archaeological and sedimentary evidence in the west and central carpathian basin: an overview with documentary comparison 7 mer cellar under the refectory close to the danube (western side of the friary), and the establishment of the other, new cellar far from the danube (eastern side of the friary), carved into the rock of the hill presumably occurred in the same time. based on these features, the location of the friary, the stratigraphy and morphological conditions of the area, the excavators presume that this major damage, occurred some time between 1514 and 1540, had strong connections with danube floods happened around the same time, and also with the generally rising trend of danube water levels. compared to the palace area and the urban settlement centre, the franciscan friary was more seriously affected by these floods. similar situation was observed during the 2002, 2006 and 2013 flood events (e.g. water was standing in the former, medieval cellars). this observation offers an explanation for the major damages of the northern cloister walk, while no similar damages were detected during floods in the palace area. in case of the franciscan friary in visegrád three conclusions were drawn on the basis of the excavated features. the building process of the friary in the 1420s was preceded by a significant ground-level rise compared to the previous ground level of the 14 th -century buildings. this ground-level rise was probably necessary because of the long-term rise in danube (flood) water levels (as described also by héjj for other parts of the town). the great flood events of the 1500s and/or the floods of the entire late 15 th –early 16 th -century flood peak as well as the above described long-term waterlevel rise had a clear impact on the early 16th-century rebuilding processes in the form of a significant rise of ground level, and also with the infill of the cellars located close to the danube (kiss and laszlovszky, 2013). between 1514 and 1540 at least one or more destructive flood events had to have strong impacts in the area which caused considerable damage in the buildings, so that a major reparation had to be carried out. concerning these decades, as shown in fig. 1, the great 1515 flood event or the series of flood events reported prior to 1523 (see later the case of margit island) or the floods around 1529-1531 as well as in the mid-1530s could be responsible for these damages (see fig. 1). all these floods or flood series, otherwise, were also reported either on the austrian or the bavarian sections of the danube (more information: kiss and laszlovszky, 2013). increasing 14 th -16 th -century groundwater levels near the danube? the example of vác related to the late medieval–early modern, long-term danube water-level rise, interesting observations were recently published concerning the medieval-early modern vác (mészáros and serlegi, 2011). the authors found it possible that already in the 15 th century a cellar had to be filled up (by litter) because of the generally rising groundwater-level conditions, which strongly depended on the danube water levels. in general, a significant increase of groundwater level was detected between the 13 th –14 th and the 16 th -century situation. similarly, the bottom of the well, constructed in the second half of the 16th century, was 1.7 m higher than the bottom of the wells constructed one-two centuries before. it is really interesting, however, that the 17 th -century well had a bottom ca. 60 cm lower then the late 16 th -century one. same observations were made in case of other, 17 th – 18 th -century wells, which were all somewhat deeper than the late 16th-century one. the bottom of the 19 th -century well was 2 m deeper than the 14 th –15 th -century ones. nevertheless, in this later, 19 th -century case the groundwater level could be already influenced by the increased water take-off due to strong population growth. thus, for the 16 th -century, with no elevation change of the surface (ground) level, the authors reco nstructed rather high average groundwater levels. based on the observations carried out in wells and cellars, the average groundwater level of the (late) 16 th century was much higher than in the middle ages, or in other parts of the early modern times, but also much higher than in the 19 th century. in general, similarly to the observations of miklós héjj (1988) concerning the rising water-level conditions of the danube between the 14 th and 16 th centuries, a significant groundwater-level rise, presumably influenced by the water levels of the danube, was reconstructed by mészáros and serlegi (2011) concerning the same period in vác. it is also important to note that the highest water level was reconstructed for the second half of the 16 th century, and already lower water levels were detected in the 17 th century. the second half of the 16 th century was also a very important period on the danube (and also on most of its tributaries), especially because of the unusually great number of extraordinary (summer) floods. significant floods especially were detected in the late 1560s–early 1570s when almost in each year there were great and extraordinary flood events (see fig. 1); but already the 1550s as well as the 1580s1590s are important flood decades (kiss, 2012b; kiss and laszlovszky, 2013; for great floods of the austrian sections: rohr, 2007; sonnlechner et al., 2013; for the danube at ulm: glaser, 2008; for major bavarian tributaries: böhm and wetzel, 2006). it could easily happen that these flood events were combined with generally higher water-level conditions on the long-term, detected in the archaeological evidence (e.g. at vác). flood risk, early 16 th -century building process and holy bones: the margit island (budapest) on the margit island (a danube island located between buda and pest) before the turkish occupation of the buda area in 1541, the last great building process on the dominican nunnery complex and the royal manor started in the late 15 th century, continued in the early 16 th century. the early 16 th -century re-building of the royal manor, located nearby the monastic church, had some elements which, according to the excavating archaeologist, served the purposes of flood defence: the floor level was raised with 40-60 cm, and buildings were surrounded by large stone sheets in the open spaces (irásné, 2004b). according to feuerné (1971), another archaeologist working before in the same excava8 kiss and laszlovszky (2013) tion area, the tomb of margit could be emptied years before 1529, because the nuns – referring to the devastations of floods – had previously removed the holy remains. although without any further reference on the source, the author presumably referred to the charter issued in 1523 which contained the permission for changing the location of margit's bones due to its flood-endangered place (hna dl 25312; for a recent overview, see vadas, 2013). an earlier building process was also detected on the mid 13th-century monastic sites, which started around 1381 and was still going on in 1409 (feuerné, 1971). thus, in case of the dominican monastery at least two flood-risk periods can be identified: one occurred in the early 16 th century (or short before), and the other, occurred in and (short) before 1523. concerning the available documentary evidence, the earlier, archaeological evidence can be easily connected to the great flood peak of the (late 15 th – ) early 16th century. nevertheless, the second (documentary) case referring to significant floods prior to 1523, with currently no available single flood references, might need more explanation. although in the carpathian basin (apart from the great flood in 1515) at the moment no contemporary reference on danube floods is available, important danube floods were reported concerning the austrian and bavarian sections in 1520 (melk; see: pertz, 1851), 1522 and 1524 (regensburg; see: heigel, 1878). moreover, the traun river, which is a good indicator of the conditions in the eastern alpine catchment of the danube, had a significant flood period at that time: damaging flood events (sometimes three in a year) occurred in each year between 1519 and 1522 (rohr, 2006). main flood peaks detected in the 14 th -16 th century: discussion as for a conclusion and discussion of results, it is useful to have an overview of the evidence listed above according to main reference periods (see fig. 4). the 14 th -15 th centuries in case of the visegrád and vác archaeological investigations, either based on settlement change observations or well depth measurements, a significant increase of water-levels, under the presumable direct influence of the danube, was suggested concerning the (14 th –)15 th and 16 th centuries (héjj, 1988; mészáros, 2006; mészáros and serlegi, 2011). in the second half of the 14 th century, after the destruction of wooden buildings, the ground-level rise of the yards (accompanied by change to a brick based building structure) was observed in šamorín (urminský, 2005). a significant ground-level rise was also detected at the building process of the franciscan friary in the 1420s, compared to the earlier, 14 th -century level of the settlement. in connection to this question, it might be also interesting to see whether or not any change could be detected at such a floodsensitive location as the margit island during the late 14 th and early 15 th century building process. as for the danube flood information preserved in documentary evidence, both in austria and hungary a clear increase was detected in the reported number of large flood events in the first decades of the 15 th century. although more danube flood references could be found in the carpathian basin in the 15 th than in the 14 th centuries, and this is especially true for the first and last decades of the 15th century, this difference can be also caused by the differences in documentation between the two centuries. more floods (also danube floods) are mentioned in the carpathian basin from the end of the 14 th century, but especially in the first decades of the 15th century, when long-term problems were as well documented (see fig. 1; and kiss 2011, 2012a). the increased number of large flood events on the danube in the early 15 th century is also clearly detectable in the contemporary austrian documentation (rohr, 2007). whereas a somewhat increased flood activity can be witnessed in the upper-danube flood reconstruction referring to ulm, not much sign of a high flood frequency period is yet found around the turn of the fig. 4 an overview of 14 th –16 th -century danube flood related archaeological-sedimentary evidence in the west and central carpathian basin (14th-)16th-century danube floods and long-term water-level changes in archaeological and sedimentary evidence in the west and central carpathian basin: an overview with documentary comparison 9 14 th –15 th centuries or in the early 15 th century (compared to, for example, the extreme flood peaks of the late 17 th or the mid 18 th centuries). a moderate increase in recorded flood events are presented concerning the second half of the 15 th century (for the danube flood reconstruction at ulm, see glaser, 2008). thus, some of the archaeological evidence (e.g. vác and visegrád) suggests long-term rising water-level conditions of the danube between the 14 th -16 th centuries. moreover, some late 14 th or early 15 th -century changes in building processes (e.g. ground-level rise: visegrád, šamorín) were also detected. in case of visegrad this was explained by the generally rising (flood) water levels, but these processes might be also connected to the flood peak at the end of the 14 th , but especially in the first decades of the 15 th century. therefore, further investigations are needed to identify the nature of this relationship. more evidence is available from the late 15 th century when new building processes started in a number of places along the danube: a ground-level rise was clearly detected, for example, in case of the new building process of the franciscan friary in visegrád. since most of related archaeological evidence were dated to the late 15 th –early 16 th centuries without further specification on timing, the late 15 th century is discussed bellow together with the early 16 th century. the (late 15 th and the) 16 th centuries the relationship is more straight-forward and easily detectable concerning the late 15 th and 16 th centuries: the much larger number of archaeological and sedimentary evidence culminate around the late 15 th –early 16 th century and mid 16 th century, as well as around the second half of the 16 th century. in all three cases already a significant number of documentary evidence is available for studying the possible relationship between flood peaks, long-term water-level changes and some of the available archaeological and sedimentary evidence. considering long-term groundwater-level changes in relation with the danube, in case of vác investigations showed clear difference between the late medieval situation of lower water levels, and the highest, late 16 th -century water levels. compared to the late 16 th century high water levels detected in wells, the 17 th century again showed a contrast with its lower waterlevel conditions. the flood (or floods), marked by a gravel-loess layer in nagymaros, could have occurred any time between the late 15 th and the 17 th centuries. while in these two cases no exact dates or decades of flood processes can be detected (except for the very high late 16 th -century water levels), in other cases the changes can be more clearly connected to certain decades, and therefore, it is possible to discuss them in time division. 1) the late 15 th and early 16 th centuries: as we could see, a significant rise of yard levels (1.5 m) was reconstructed in šamorín, while an important (over half meter) ground-level rise could be also detected in the early 16 th century, both in case of the visegrád friary and the dominican nunnery at the margit island. the influence of great flood events is probably the most clearly detected in the visegrád cases. another clear consequence was the infill of cellars (due to repeated flooding), detected both in visegrád town centre and in case of the franciscan friary. in documentary evidence, primarily based on the information related to bratislava, a significant flood peak was reconstructed concerning the late 15 th and early 16 th centuries: starting with 1478, the 1480s, 1490s and 1500s were especially rich in destructive flood events. moreover, the extraordinary flood events occurred on the austrian sections of the danube in 1501 ("millennium flood"), 1503 and also in 1508, which great flood waves presumably also appeared on the carpathian basin sections. observations concerning the early 16 th -century significant ground level rise as well as the infill of cellars due to flood danger show parallels to what happened after 1501 along the austrian sections of the danube (see rohr 2005): apart from rising ground levels concerning new building processes, in engelhartzell after the 1501 flood the toll house had no windows at the ground floor. great flood(s) after the early 1510s caused significant damages in the franciscan friary of visegrád: based on documentary information, in this case either the great 1515 flood event, the flood series prior to 1523 or the (great) floods around 1530 (1529, 1530, 1531) as well as in the mid 1530s (1535, 1537) might be responsible for the major damage. 2) mid-16 th century and the second half of the 16 th century: as for the upper sections of the danube, at orth concerning the rapid in-fill process of a harbour, high intensity sedimentation process (which could as well be connected to a higher number of more intense flood events) was detected around or short after 1550. this event might be a process parallel to the great 1548 flood event or the floods of the 1550s. in vác the highest water levels in wells were detected in the second half of the 16 th century (mészáros and serlegi, 2011); the nagymaros gravel-loess layer was also dated by the same authors for the mid or late 16 th century. parallel investigations suggest the intensification of fluvio-morphological processes (increased channelling activity and sedimentation) around the same time on the danube in the bratislava and žitný ostrov area as well as at the lower sections of the river morava. these processes correspond to the great flood peak, especially documented concerning the second half of the 16 th century, culminating around the late 1560s and early (mid) 1570s, characterised by great material damages and long-lasting inundations (e.g. in the bratislava and žitný ostrov area in 1574). conclusion and outlook in a growing number of cases, results of archaeological and sedimentary investigations can be directly or indirectly connected to large danube flood events, series of floods 10 kiss and laszlovszky (2013) events and/or general, long-term changes in water-level conditions. the processes detected in archaeological evidence are partly long-term changes: a general rise of the danube (flood) water levels were detected concerning the 14 th -16 th centuries. this water-level might have reached its peak in the second half of the 16 th century. medium and short term evidence mainly corresponds to the main flood peaks or even to single catastrophic flood events. such processes may be identified in archaeological evidence concerning the second half of the 14 th , early 15 th centuries; while most of the cases listed above were connected to the flood peak (and/or generally increasing water-level conditions) of the late 15 th and early 16 th centuries. in other cases connections between sedimentary/archaeological evidence and the midand late 16 th -century high flood-frequency period were presumed. documentary evidence referring to the same period suggests that higher flood frequency and intensity periods occurred in the early and mid 16 th century; a probably more prolonged one took place in the second half of the 16 th century, with a peak in the late 1560s-early 1570s and maybe with another at the end of the 16 th century. earlier flood peaks in documentary evidence were detected on the danube at the turn of the 14 th -15 th centuries and in the last decades of the 15 th century, continuing in the early 16 th century. comparing the above-mentioned results with the only available, systematic long-term upper-danube flood reconstruction (see glaser, 2008: for ulm, germany), some clear similarities and differences can be recognised: based on the available documentary evidence, in ulm a (smaller) flood peak was reconstructed for the second half of the 14 th century, and a moderate increase in the second half of the 15 th century. the real 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(ed.). anuarul scolii doctorale. „istorie. civilizaţie. culturǎ“ v. cluj-napoca: accent, 77–101. vadas, a. 2013. long term perspectives on rover floods. the dominican nunnery on margaret island (budapest) and the danube river. interdisciplinaria archaeologica 4/1 (2013): 73-82. wstla, bürgerspital = wien staatund landesarchiv, bürgerspital b 11spitalmeisterrechnung; spitalmeisteramtsrechnung, bd. 26 (1548). environmental armed conflict assessment using satellite imagery journal of environmental geography 13 (3–4), 1–14. doi: 10.2478/jengeo-2020-0007 issn 2060-467x environmental armed conflict assessment using satellite imagery fernando arturo mendez garzón¹*, istván valánszki¹ ¹szent istván university (szie), department of landscape protection and reclamation +36-1-305-7387, h-1118 budapest, villányi út 29-43 *corresponding author, e-mail: famendezg@yahoo.com.mx research article, received 8 february 2020, accepted 11 august 2020 abstract armed conflicts not only affect human populations but can also cause considerable damage to the environment. its consequences are as diverse as its causes, including; water pollution from oil spills, land degradation due to the destruction of infrastructure, poisoning of soils and fields, destruction of crops and forests, over-exploitation of natural resources and paradoxically and occasionally reforestation. in this way, the environment in the war can be approached as beneficiary, stage, victim or/and spoil of war. although there are few papers that assess the use of remote sensing methods in areas affected by warfare, we found a gap in these studies, being both outdated and lacking the correlation of remote sensing analysis with the causes-consequences, biome features and scale. thus, this paper presents a methodical approach focused on the assessment of the existing datasets and the analysis of the connection between geographical conditions (biomes), drivers and the assessment using remote sensing methods in areas affected by armed conflicts. we aimed to find; weaknesses, tendencies, patterns, points of convergence and divergence. then we consider variables such as biome, forest cover affectation, scale, and satellite imagery sensors to determine the relationship between warfare drivers with geographical location assessed by remote sensing methods. we collected data from 44 studies from international peer-reviewed journals from 1998 to 2019 that are indexed using scientific search engines. we found that 62% of the studies were focused on the analysis of torrid biomes as; tropical rainforest, monsoon forest / dry forest, tree savanna and grass savanna, using the 64% moderateresolution satellite imagery sensors as; landsat 4-5 tm and landsat 7 etm+. quantitative analysis of the trends identified within these areas contributes to an understanding of the reasons behind these conflicts. keywords: armed conflict, biomes, land use change, remote sensing, deforestation introduction the complex relation between warfare and environment has been studied relatively little; one exception is the report on the protection of the natural environment in armed conflict made by the international law and policy institute ilpi (2014). the report shows that war may generate large damage to the environment and populations that depend upon natural resources. attacks produce direct harm on animals, vegetation, soil, and water systems, with consequent impacts on local or regional ecosystems. vast defoliation campaigns are also utilized by combatants to realize strategic dominance. meanwhile, serious contamination may incidentally result as an outcome from attacks on industrial sites, oil wells or other infrastructure (gorsevski et al., 2012; hanson et al., 2008; ilpi, 2014; jha, 2014; le billon, 2001; murad and pearse, 2018; potapov et al., 2012; butsic et al., 2015). secondary consequences such as displacement may in turn take tolls on the natural environment (leiterer et al. 2018; sanchez-cuervo and aide, 2013). in some cases, the environmental impacts of warfare extend over large regions and continue for years or perhaps decades after the conflict finishes. the armed conflict is a less well-studied driver of deforestation (machlis and hanson, 2008; butsic et al., 2015), which is unfortunately recurrent in tropical forests worldwide (geist and lambin, 2002; gorsevski et al., 2012; hecht and saatchi, 2007). empirical investigations as ilpi (2014) suggest a complex link between warfare and forest conservation (armenteras et al., 2006; draulans and van krunkelsven, 2002; gorsevski et al., 2012; rustad et al., 2008). additionally, machlis and hanson (2008) and butsic et al. (2015) have widely studied the direct effects of the conflict that includes road building, deforestation, and unsustainable use of natural resources. indirect effects may include reduced economic activity during the wartime, which could reduce vegetation cover, and increase changes in land use (jha, 2014; stevens et al., 2011). it has been proven that these impacts remain in post-conflict times (nackoney et al., 2014). notwithstanding, experimental researches indicate that warfare may have both negative and positive results regarding wild forest conservancy (rincon-ruiz et al., 2013; rustad et al., 2008) even in local areas (gorsevski et al., 2013, butsic et al., 2015). additionally, the effectiveness of protected areas in times of hostilities also modifies over space and time (de merode et al., 2007). the appraisal of the implications of warfare on the environment is especially challenging due to the endogenous nature of vegetation cover loss and lan d2 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. use changes. warfare is also the outcome and/or the reason behind deforestation, implying a tight, unique, and particular relation. neglecting this particularity in models of deforestation can produce biased coefficients and standard errors, thus constra ining our ability to know the causal structure between warfare and deforestation in a statistical frame (blackman, 2013; butsic et al. 2015). ordway (2015) has demonstrated that wartime and post-conflict period may relate to land use and land cover activities to clout the alteration of the landscape and increase forest deterioration. land use changes have promoted the devastating deterioration in biodiversity through habitat dissolution, modification and destruction, resulting in the decline of ecosystems and environmental services (jha, 2014; kwarteng, 1998; ordway, 2015; nackoney et al., 2014; qamer 2012 et al., 2005). the increasing amount of literature framing various direct and indirect consequences of armed conflict on the environment has created diverse hypotheses (black, 1994; jarret, 2003; machlis and hanson, 2008; mcneely, 2003; omar and bath, 2009; ordway, 2015). in fact, some assessments have shown that conflict and warfare can stimulate deforestation or promote vegetation cover recovery (alvarez, 2003; biswas and tortajada-quiroz, 1996; dávalos, 2001; hecht and saatchi, 2007; lodhi et al., 1998; mcneely, 2003). armed conflict causes and effects on the environment direct causes are all activities that are physically associated with direct action of confrontation which generally appears within the immediate or short-term (bombings, direct armed confrontations, military infrastructure). while indirect causes are those that are frequently linked to several causes not necessarily military and only reveal themselves fully within the medium or long-term (jha, 2014; mendez and valánszki, 2019; partow, 2008; solomon et al., 2018) (fig. 1). some examples of direct effects encompass the intentional loss of natural resources, environmental pollution from the bombing of industrial areas, the military remains, and explosion wastes from military infrastructure. furthermore, solomon et al., (2018) affirms that indirect impacts include the ecological footprint of displaced communities (hagenlocher et al., 2012), deforestation as a result of new expansion areas, the increase of illegal crops and illegal mining, the impossibility of the implementation of the fig. 1 causes on environment based on jha, 2014 fig. 2 effects of conflict on environment based on jha, 2014 environmental regulations, and also the information gaps, in addition to the lack of funds for environmental conservation. another complementary problem is that any conflict destroys buildings and infrastructure that has to be rebuilt costing large resources and increasing emissions (jha, 2014; solomon et al., 2018) (fig. 2). witmer (2015) affirms that the impacts can be classified into four categories, arranged by time required for each consequence to be visible. for instance, physical harm generated by bomb or fire detonations is commonly an immediate effect, which appears in minutes or hours. alternative impacts like environmental damage (hours to days), population forced and unforced displacement (days to months), and changes of land cover/use (months to years) take longer to emerge. even though there is some overlap between various impacts of warfare between direct and indirect, this classification creates a convenient and methodical way of approaching research. satellite imagery and armed conflicts initially, remote sensing (rs) methods, including aerial photos, were used for analysis in conflict zones with warlike purposes. this is due to the military sector having for a long time been a source of technological innovation with enough financial resources to invest in rs research (corson and palka, 2004). advances in photography, airplanes, and satellites have largely improved the efficacy of battleground monitoring, with many military helicopters, airplanes, and unmanned aircraft systems (uass) now capable of grabs video evidence registering the effectiveness of air and ground attack missions. improvements in rs technology and satellite imagery have increased the effectiveness of armies and the accuracy of military operations (witmer, 2015). the complicated access to a zone in wartime combined with a diffuse spatial and/or temporal definition makes a precise and timely evaluation of the effects highly demanding (gorsevski et al., 2012; uriarte et al., 2010; butsic et al., 2015). due to these restrictions, info acquired from satellite imagery can bring a wide vision of how confrontations affect directly the physical environment during wartime and post-conflict, and how indirect causes drive shifts in local communities, land-uses and land-covers (hoffmann et al., 2018; murad & pearse, 2018). as a result of the cause-consequence complex interdependence generated by the warfare and the need for larger protection efforts, the link between conflict mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. 3 and ecosystem needs to be investigated more deeply (ordway, 2015). resolution is a major aspect of the usage of rs methods. spatial, spectral, and temporal resolutions are perchance the most important but radiometric resolution also affects what can be perceived. table 1 lists the sensors frequently used to detect the effects of armed conflict. the sensors are grouped by spatial resolution which are very fine ≤1 m, fine >1-10 m, moderate >10–120 m, and coarse >250 m. aim although we found two studies that assess the use of rs analysis in areas impacted by armed conflicts (solomon et al., 2018; witmer, 2015), these studies present a gap in research because they do not cover many types of research related to conflicts and environment. furthermore, these studies are outdated regarding the latest rs methods and satellite sensors. the diversity of methods, classifications, satellite imagery sensors, and approaches for rs calls for a systematic revision that addresses their relation to conflict features such as biome type and geographical location, conflict causesconsequences, and the study area scale. our aim is the assessment of the existing studies to identify relationships and patterns (and, implicitly, differences) in order to methodically approach the warfareenvironment issue within an accurate and integral view for each specific type of conflict in future investigations. this study seeks to offer an overview of the most important tendencies in the usage of rs as a tool for environmental damage assessment in warfare areas. our aim is to demonstrate the specific correlation between armed conflicts (causes) and environment (consequences) using state-of-the-art rs technology to provide conditioned geospatial environmental information. more exactly, this paper presents an integrative and transferable approach for the quantification, systematic comparison, and evaluation of the rs studies used in zones affected by armed conflicts. the impacts outlined in this paper, such as deforestation or land-use/land-cover changes, were quantified systematically and in exclusive regard to their rs analysis. this means that results here provided are considered applicable and relevant for the analysis of rs studies and are not necessarily applicable nor usually considered accurate for armed conflicts in general. other scopes will be considered in future investigations. table 1 characteristics of commonly used sensors sensor spatial resolution [m] swath width [km] spectral bands operating period active domain origin very fine spatial resolution (≤1m) geoeye 0.46 10 pan 09-2008 currently yes pr us world view ii 0.46 18 pan 10-2009 currently yes pr us quickbird ii (pan) 0.6 30 pan 10-2001 to 12-2014 no pr us ikonos (pan) 0.82 1 11 pan 09-1999 to 03-2015 no pr us fine spatial resolution (>1–10m) geoeye 1.84 10 4 09-2008 currently yes pr us quickbird ii (ms) 2.4 30 4 10-2001 to 12-2014 no pr us alos 2.5 pan 01-2006 to 05-2011 no pu jp spot-5 2.5, 5, 10 60 pan 05-2002 to 03-2015 no pu fr cbers-2b 2.7 27 pan 09-2007 to 06-2010 no pu cn-br ikonos (ms) 3.28 – 4 11 4 09-1999 to 03-2015 no pr us kvr-1000 (ms) 3.3 40 4 1994 n.d. no pu ru rapid eye 5 77 5 02-2009 to 03-2020 no pr de-uk google earth vhr 5, 10 n.a. pan n.a. yes pr us irs 1c liss iii 6 70 pan 12-1995 09-2007 no pu in moderate spatial resolution (>10–120m) sentinel 2 10, 20, 60 290 13 06-2015 currently yes pu eu aster 15, 30, 90 60 14 02-2000 currently yes pu us-jp landsat 8 oli 15, 30 185 11 02-2013 currently yes pu us landsat 6-7 etm + 15, 30 185 8 10-1993 currently yes pu us irs 1c liss iii 23, 50 142 4 12-1995 to 09-2007 no pu in landsat 4-5 tm 30 185 7 07-1982 to 06-2013 no pu us landsat 1-3 mss 60, 120 n.d. 4 07-1972 to 01-1983 no pu us coarse spatial resolution (>250 m) modis 250, 500, 1000 2330 36 1999 to 2005 no pu us viirs 375, 750 3060 22 10-2011 currently yes pr us avhrr 1100, 4400 2500 5, 6 03-2004 currently yes pu us-eu radar data no category lidar 1 n.a. n.a. n.a. yes pr n.a. aerial photos n.a. n.a. n.a. n.a. pr / pu n.a. abbreviations: (n.d) no date, (n.a.) not applicable, (pan) panchromatic, (pr) private, (pu) public 4 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. the questions motivating this paper are: • what is the relationship between remote sensing sensors and the geographical / biome location of the study area? • how are the remote sensing sensors and the scale of the study area related? • what is the relationship between causes generated by the armed conflict (indirect and direct drivers) and the study area type of biome? • what is the relationship between armed conflict consequences and the study area type of biome? materials and methods rs assessment has been used at least in 21 countries across 4 continents as an approach to armed conflict and their environmental effects. for the data collection and the analysis of methods, we looked for articles and data sets through scientific search engines using t he following keywords: “remote sensing + armed conflict”, “biomes + armed conflict” and “deforestation + armed conflict”. then we made a filtered search based on the indicators (satellite sensor, resolution, scale, cause, consequence, biome, location, imagery preprocessing, etc.). we collected and analyzed 116 studies. after a second and deeper revision, we chose 44, documents that fulfilled all or almost all the parameters required for the assessment. these are listed in table 2. the documents were read, evaluated, synthesized, and tabulated for their processing. although the studies analyzed were carried out from 1998 to 2019, they do not necessarily correspond to the time when the armed conflicts occurred. the majority of the studied armed conflicts occurred between 1980 and the present. in order to evaluate the datasets from 44 studies that used satellite imagery and aerial photos, we framed the assessment seeking the following parameters: study area size, armed conflict causes and consequences, types of causes (direct or indirect), affectation of forest cover (increase or decrease), time-lapse, satellite imagery sensor, spatial resolution, conflict period, imagery preprocessing, imagery classification, geographical location, and type of biome. quantitati ve analysis of the parameters identified within these studies contributed to an understanding of the reasons behind these consequences. their correlations can be useful for future research suggestions and can work as a guideline of rs assessment in areas affected by conflict. besides the assessment of satellite resolution, we analyzed the micro and macro-level consequences that can be drawn in the resulting inventory mapping of comprises statistics charts, patterns, trends, and findings on rs and its relationship with the armed conflict. this was done in the context of a comprehensive review, processing, tabulating, appraising, and synthesis of collected data. table 2 features of remote sensing studies of armed conflict repercussions in the environment country scale (km2) causes consequences sensor reference kuwait re bo lu, lc ls4-5 abuelgasim et al. 1999 n. macedonia, palestine re n.d. n.d. ikonos al-khudhairy et al. 2005 colombia re 42000 ag, cr, ti df ls1-3, ls4-5, ls6-7 armenteras et al. 2006 colombia na 1,142,000 nfm, ic, ag, cr, ti, fi df ls4-5, ls6-7 armenteras et al. 2013 thailand lo fm lu kvr-1000 bjorgo 2000 sierra leona re 71740 bo, dc, mi df ls4-5, ls6-7 burgess et al. 2015 colombia na 1,142,000 mn, ag, cr df, lu ls6-7, ls8, aster, se, cbers, re cabrera et al. 2019 colombia re ic df ls6-7 chadid et al. 2015 liberia la 1639 dc, mi, fm, ms, ag df, ds, lu, lc ls4-5, ls6-7, ls8 enaruvbe et al. 2019 colombia re 25000 fm, cr df, lu, lc aster garcia-corrales et al. 2019 sierra leona lo 557 fm, nfm, ag df, lu, lc spot-5, ls1-3, ls4-5, ls6-7 gbanie et al. 2018 belgium la 2500 bo mi ap, als gheyle et al. 2018 colombia lo 935 mn df, lu ls6-7 gómez-rodríguez et al. 2017 s. sudan, uganda la 8375 fm df, fo, ds, aal ls4-5, ls6-7, modis, ap gorsevski et al. 2012 south sudan la 1032 fm df spot-5 gorsevski et al. 2013 south sudan la fm df, ds, ld, gw qb hagenlocher et al. 2012 el salvador re 21000 fm df ls4-5, modis, avhrr hecht and saatchi 2007 afghanistan la ic, ag, cr df, lu, lc, aal ge, ls4-5 ingalls and mansfield 2017 kuwait la bo, dc, mi lu ls4-5 kwarteng 1998 colombia na 1,142,000 dc, mi, fm df, lu, lc n.d. landholm et al. 2019 south sudan la fm df, lc ls4-5, ls6-7, ls8, wv2 leiterer et al. 2018 arab countries na bo, dc, mi aal viirs levin et al. 2018 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. 5 results armed conflict & remote sensing assessment by biomes unlike countries' borders, biomes' physical limits are rarely clear or defined. as a result, several studies may cover two or more biomes. within the 44 investigations assessed, we found the use of rs in the study of 13 general types of biomes and the assessment in 92 different cases. this means that each study could have used more than one sensor to assess two or more biomes, depending on the area, complexity, and the availability of satellite imagery data set. the analysis outcome regarding the number of studies by biome indicates that high biodiversity spots near the equatorial line such as tropical rainforest (23), monsoon forest/dry forest (17), tree savanna (7) and grass savanna (6) cover the biggest number of studies. furthermore, we found a considerable number of studies located in subtropical areas, a diverse number of biomes as a montane forest (13) temperate broadleaf forest (5), semi-arid desert (4), alpine tundra (4), subtropical dry forest (4) and subtropical rainforest (1). finally, we identified few studies performed in the temperate biomes; mediterranean vegetation (3), dry steppe (2), and xeric shrubland (1) (fig. 3 & 4). relationship between satellite imagery sensors and biomes regarding the satellite sensors used, we observed that two-thirds (64%) of the biomes were analyzed by sensors with moderate resolution (10-120 m) where landsat 4-5 tm and landsat 7 etm+ stand out (e.g., armenteras et al., 2013; butsic. et al., 2015; gorsevski et al., 2012; leiterer et al., 2018; murad and pearse, 2018). we found that very fine (≤1m) and fine (1 10m) resolution sensors covered 23% of the biomes, with spot-5 and quickbird ii sensors slightly standing out (e.g., petit et al., 2001; qamer et al., 2012). country scale (km2) causes consequences sensor reference pakistan lo 618 fm df ls1-3, ls4-5 lodhi et al. 1998 cambodia lo 50 bo, dc, mi df ls6-7 loucks et al. 2009 colombia la 3927 mn, ag lc ls6-7, ls-8 monroy and armenteras 2017 colombia re ic, ag, cr df, lu, lc ls6-7, ls-8 murad and pearse 2018 r.d. congo la 1510 fm df, lu, lc ls4-5, ls6-7 nackoney et al. 2014 colombia na 1,142,000 dc, mi, ic df n.d. negret et al. 2019 belgium lo 142,5 bo mc ap note et al. 2018 rwanda la 271 fm, nfm, ag, ti df ls4-5, ls6-7, aster ordway 2015 r.d. congo la fm, nfm lu, lc ls4-5, ls6-7, ls8, gevhr, wv2 pech and lakes 2017 zambia lo 217 n.d. df, lu spot-5 petit et al. 2001 r.d. congo na 2,345,409 fm, nfm, mn df qb, ls6-7 potapov et al. 2012 pakistan la 4109 fm, ag, cr df, lu spot-5, ls4-5, ls6-7, aster qamer et al. 2012 colombia na 1,142,000 n.d. df, lu, lc qb, ge-vhr, modis sánchez-cuervo and aide 2013 south sudan re 23000 fm lu, lc modis sosnowski et al. 2016 nicaragua la 1600 fm df ls1-3, ls4-5 stevens et al. 2011 belgium la 1560 bo mc ap, als stichelbaut et al. 2016 sri lanka la 1125 dc, mi, lm, fm, ti df, lu, mi ls4-5, irs suthakar and bui 2008 myanmar na 236342 ic df, lu, lc spot-5, qb, ikonos, alos, aster tian et al. 2011 r.d. congo na 2,345,409 dc, mi, mn df, lu, lc, mi, aal ls4-5, ls6-7 van butsic et al. 2015 turkey la 7600 bo, dc, mi df, lu, lc ls4-5 van etten et al. 2008 sierra leone la 5397 n.d. df, lu, lc ls4-5 wilson and wilson 2013 bosnia & herzegov. re 3887 bo, lm, fm lu, lc ls4-5, ls6-7, qb witmer 2008 abbreviations: (n.d) no date, (n.a.) not applicable scale: (lo) local 0-999 km2, (la) landscape 1000-9999 km2, (re) regional 10000-99999 km2, (na) national/global ≥100,000 km2 causes: (ag) agriculture, (bo) bombing, (cr) cattle ranching, (dc) direct confrontation, (fi) fires, (fm) forced migration, (ic) illegal crops, (lm) landmines, (mi) military infrastructure, (mn) mining, (nfm) non-forced migration, (ti) timber consequences: (aal) abandonment of agricultural lands, (df) deforestation, (ds) desertification, (fo) forestation, (gw) groundwater pollution, (lc) land cover changes, (ld) land degradation, (lu) land use changes, (mc) mine craters, (mi) military infrastructure. sensor: (alos) advanced land observation satellite, (als) lidar airborne laser scanning, (ap) aerial photo, (aster) advanced spaceborne thermal emission and reflection radiometer, (avhrr) advanced very-high-resolution radiometer, (cbers-2b) china–brazil earth resources satellite, (ge-vhr) google earth very high resolution, (ge) geoeye, ikonos, (irs) irs-1c liss-iii indian remote-sensing satellite, kvr-1000, (ls1-3) landsat 1-3 mss, (ls4-5) landsat 4-5 tm, (ls6-7) landsat 6-7 etm+, (ls8) landsat 8 oli, (modis) moderate resolution imaging spectroradiometer, (qb) quickbird ii,(re) rapid eye, (se) sentinel 2, (spot-5) satellite pour l’observation de la terre, (viirs) visible infrared imaging radiometer suite, (wv2) worldview-2 6 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. uncategorized sensors covered 7% of the biomes, aerial photographs, and lidar als sensor stands out within this segment (e.g., note et al., 2018). finally, coarse sensors (>250 m) covered 6% of the biomes in which modis sensor was the most outstanding (e.g., gorsevski et al., 2012; hecht and saatchi, 2007; sánchez-cuervo and aide, 2013; sosnowski et al., 2016) (fig. 5). table 3 was obtained after crossing the data between the study area type of biome and the satellite imagery sensors used for rs. the outcome indicates that the most common satellite imagery sensors used was the moderate resolution sensors (10-120 m) with 61% of the total, mainly landsat 4-5 tm and landsat 7 etm+ in the analysis of biomes such as tropical rainforest, monsoon forest/dry forest, montane forest, and tree savanna. the very fine (≤1 m) and fine (1-10 m), resolution sensors were used in 27% of the studies per biomes; spot 5, quickbird, and google earth vhr have been used noticeably more in the study of biomes such as tropical rainforest, monsoon forest/dry forest, montane forest, tree savanna, and grass savanna. geoeye sensor was used once each in non-common biomes as xeric shrubland, dry steppe, and alpine tundra. sensors with coarse resolution (>250 m) were utilized in the 8% of the total and highlight the use of modis for several types of biomes. uncategorized sensors were used rarely (4% of the total). aerial photos and lidar als were used mainly in the temperate broadleaf forest. fig. 4 biomes analyzed for occurrence in the studies relationship between satellite imagery sensors and study area scale to analyze and study the relationship between the use of satellite image sensors and the scale of the area affected by armed conflict, we first categorized the scale sizes into four types: local (0-999 km2), landscape (1000-9999 km2), regional (10,000-99,999 km2) and national/global (≥100,000 km2). then, we checked, crossed the data and created a correlation table to identify trends and patterns of repetition. we obtained the following results: moderate resolution (10-120 m) sensors such as landsat 4-5 tm, landsat 7 etm+ and to a lesser extent landsat 8 oli are the most widely used sensors in all scales, is noticeable a clear trend in the use of these sensors mainly in studies of medium to large small such as landscape (e.g., gorsevski et al., 2012; gorsevski et al., 2013; leiterer et al., 2018; monroy and armenteras, 2017; van etten, 2008), and regional (e.g., armenteras et al., 2006; burgess et al., 2015; hecht and saatchi, 2007; witmer, 2008). fig. 5 distribution by satellite sensor fig. 3 armed conflict causes analyzed using remote sensing by biomes and countries mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. 7 in addition, we observed that high (1 -10m) and very high-resolution (≤1m) satellite image sensors such as quickbird, ikonos, rapideye, and cbers were barely used in studies that analyzed sites with small scales such as regional (10,000-99,999 km2) and national/global (≥100,000 km2) excepting spot-5 and kvr-1000 that were used mainly in smaller scales. concerning coarse (>250 m) sensors, the use was very low with the modis sensor standing out slightly on the regional scale. the aerial photos and als sensors were used primarily in researches that use landscape scale. several studies used more than one sensor to fulfil the gaps of information that the use of a single sensor can offer. this produces that each study can use the satellite images from more than one sensor mainly when landsat data does not provide sufficient cloud-free coverage imagery or the availability does not cover the required period (table 4). preprocessing of satellite imagery sensors preprocessing involves geometric (orthorectification) and radiometric calibration. geometric calibration corrects for the angle of sight of the satellite sensor, the relief of the ground, and lens distortions in order that images from different sensors at different times may be compared with the same way as maps made using the identical projection and scale (warner et al., 2009). radiometric calibration is recommended due to the appearance of the identical image varies with the angle of view and radiance conditions. of the 44 studies analyzed, 18% mentioned explicitly the utilization of satellite imagery preprocessing methods. for the reflectance calibration and image normalization, topof-atmosphere (toa) data was used 15 times in five studies (e.g., cabrera et al. 2019; enaruvbe et al. 2019; potapov et al. 2012; stevens et al. 2011; wilson and wilson 2013). in the case of top of canopy (toc) reflectance data sets were performed just in one study (potapov et al. 2012) with two satellite imagery sensors. finally, the cloud presence was removed through atmospheric corrections using the atmospheric & topographic correction atcor-2 for haze removal in two studies with three landsat sensors (e.g., kwarteng 1998; murad and pearse 2018) (table 5). table 3 relationship between satellite imagery sensors and biomes sensor vs biome t e m p e ra te b ro a d le a f fo re st s u b tr o p ic a l r a in fo re st m e d it e rr a n e a n v e g e ta ti o n m o n so o n f o re st / d ry f o re st x e ri c s h ru b la n d d ry s te p p e s e m ia ri d d e se rt g ra ss s a v a n n a t re e s a v a n n a s u b tr o p ic a l d ry fo re st t ro p ic a l r a in fo re st a lp in e t u n d ra m o n ta n e f o re st t o ta l v e ry f in e ( ≤ 1 m ) a n d f in e ( 1 1 0 m ) spot-5 1 2 1 1 1 2 1 1 10 quickbird ii 1 2 2 1 3 1 2 12 ikonos 1 1 1 1 1 5 worldview-2 1 1 1 3 geoeye 1 1 1 3 alos 1 1 2 cbers-2b 1 1 2 kvr-1000 (ms) 1 1 2 rapid eye 1 1 2 google earth vhr 1 1 1 2 1 1 7 m o d e ra te ( 1 0 – 1 2 0 m ) landsat 1-3 mss 1 3 1 5 landsat 4-5 tm 1 1 8 1 2 2 1 3 12 2 6 39 landsat 6-7 etm+ 1 10 1 2 1 14 1 9 39 landsat 8 oli 1 1 1 1 4 2 10 aster 3 1 1 4 1 3 13 sentinel 2 1 1 2 irs-1c liss-iii 1 1 2 c o a rs e (> 2 5 0 m ) modis 2 2 2 1 4 1 3 15 viirs 1 1 2 avhrr 1 1 n o c a te g o ry aerial photo 3 1 1 1 6 lidar – als 2 2 total 7 1 5 34 2 4 3 10 15 5 57 9 32 181 8 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. table 4 relationship between satellite imagery sensors and study area scale sensor vs scale l o c a l (0 -9 9 9 k m 2 ) l a n d sc a p e (1 0 0 0 -9 9 9 9 k m 2 ) r e g io n a l (1 0 ,0 0 0 -9 9 ,9 9 9 k m 2 ) n a ti o n a l/ g lo b a l (≥ 1 0 0 ,0 0 0 k m 2 ) t o ta l v e ry f in e ( ≤ 1 m ) a n d f in e ( 1 1 0 m ) spot-5 2 2 1 5 quickbird ii 1 1 3 5 ikonos 1 1 2 worldview-2 2 2 geoeye 1 1 alos 1 1 cbers-2b 1 1 kvr-1000 (ms) 1 1 rapid eye 1 1 google earth vhr 1 1 2 m o d e ra te ( 1 0 – 1 2 0 m ) landsat 1-3 mss 2 1 1 4 landsat 4-5 tm 2 13 5 2 22 landsat 6-7 etm+ 3 8 5 4 20 landsat 8 oli 4 1 1 6 aster 2 1 2 5 sentinel 2 1 1 irs-1c liss-iii 1 1 c o a rs e (> 2 5 0 m ) modis 1 2 3 6 viirs 1 1 avhrr 1 1 n o c a te g o ry aerial photo 1 3 4 lidar – als 2 2 total 11 42 18 23 92 satellite imagery sensors and imagery classification the classifiers used for satellite image classification are split into two categories: statistical and machine learning approaches, the performance of which relies on the information distribution. the statistical learning approaches support some mathematical theories which cope with finding a relationship between classes to predict some substantial outcome (e.g., borra et al., 2019). maximum likelihood classifier was used in at least 25% of the studies. object-based image analysis (obia) classifier was utilized in just 5% of the research. the fully automated multivariate alteration detection (mad) method was used once (2%). regarding indexed classification, 25% of the assessed studies, indicated explicitly the use of normalized difference vegetation index (ndvi) as a graphical indicator to analyze rs measurements. 43 % of the studies used some type of land -cover landuse classification (lulc). additionally, 36% of the studies stated the utilization of some type of forest table 5 relationship between satellite imagery sensors and preprocessing methods sensor vs preprocessing t o a t o c a t c o r id o s t o ta l v e ry f in e ( ≤ 1 m ) a n d f in e ( 1 – 1 0 m ) spot-5 0 quickbird ii 1 1 2 ikonos 0 worldview-2 0 geoeye 0 alos 0 cbers-2b 1 1 kvr-1000 (ms) 0 rapid eye 1 1 google earth vhr 0 m o d e ra te ( 1 0 – 1 2 0 m ) landsat 1-3 mss 1 1 2 landsat 4-5 tm 3 1 1 5 landsat 6-7 etm+ 3 1 1 1 6 landsat 8 oli 2 1 3 aster 1 1 sentinel 2 1 1 irs-1c liss-iii 0 c o a rs e (> 2 5 0 m ) modis 1 1 2 viirs 0 avhrr 0 total 15 3 3 3 24 abbreviations: (toa) top of atmosphere, (toc) top of canopy, (atcor) atmospheric & topographic correction, (idos) improved dark object subtraction cover classification (fcc). other multispectral vegetation indices as enhanced vegetation index (evi) and modified soil-adjusted vegetation index (msavi) were performed in just one study each (table 6). relationship between biomes and causes generated by armed conflicts. in the table of crossed data between the causes generated by armed conflicts and the types of biomes, we found that the utilization of rs was used three times more in the analysis of indirect causes (74%) than in the analysis of direct causes (26%). regarding direct causes as bombing (10%) (e.g., burgess et al., 2015; kwarteng, 1998; note et al., 2018; witmer, 2008; van etten et al., 2008) were studied mainly at the temperate broadleaf forest, dry forest, and semiarid desert biomes. direct confrontation and military infrastructure (14%) (e.g., kwarteng, 1998; suthakar and bui, 2008; van etten et al., 2008) were assessed principally at monsoon forest / dry forest and tropical rainforest biomes. on the another hand, in the case of mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. 9 indirect causes analyzed by rs, we found that forced migration mostly affected biomes (23%) (e.g., enaruvbe, et al., 2019; hecht and saatchi, 2007; hagenlocher et al., 2012; leiterer et al., 2018; lodhi et al., 1998; suthakar and bui, 2008), mainly; tropical rainforest, the monsoon forest / dry forest, montane forest, grass savanna, and tree savanna. other relevant causes studied were agriculture (12%) (armenteras et al., 2006; murad and pearse, 2018; qamer et al., 2012), illegal crops (10%) (e.g., armenteras et al., 20 13; murad and pearse, 2018; rincón ruiz et al., 2013), cattle ranching (10%) (e.g., murad and pearse, 2018), mining (7%) (e.g., monroy and armenteras, 2017; potapov et al., 2012) and non-forced migration (6%) (e.g., armenteras et al., 2013), affecting mainly the tropical rainforest followed in decreased order by the montane forest, monsoon forest / dry forest, tree savanna, alpine tundra, and grass savanna (table 7). table 6 relationship between satellite imagery sensors and imagery classification sensor vs imagery classification n v d i l u l c f c c o b ia m o d is -e v i m l c m a d m s a v i t o ta l v e ry f in e ( ≤ 1 m ) a n d f in e ( 1 1 0 m ) spot-5 1 3 3 2 9 quickbird ii 3 2 2 1 1 1 10 ikonos 1 1 2 worldview2 1 2 1 4 geoeye 1 1 alos 1 1 cbers-2b 1 1 kvr-1000 (ms) 0 rapid eye 1 1 google earth vhr 2 1 3 m o d e ra te ( 1 0 – 1 2 0 m ) landsat 1-3 mss 2 3 1 6 landsat 4-5 tm 6 11 11 7 1 1 37 landsat 6-7 etm+ 7 12 11 5 1 36 landsat 8 oli 1 4 2 3 10 aster 2 3 5 sentinel 2 1 1 irs-1c liss-iii 1 1 2 c o a rs e (> 2 5 0 m ) modis 3 2 3 1 1 1 11 viirs 0 avhrr 1 1 2 total 22 43 45 2 3 21 3 3 142 relationship between biomes and consequences of the armed conflicts based on the analysis of the consequences of armed conflicts on the environment with the affected biomes, we found that the use of rs is strongly focused on the analysis of deforestation (46%) (e.g., armenteras et al., 2006; gorsevski et al., 2012; hagenlocher et al., 2012; murad and pearse, 2018; nackoney et al., 2014; ordway, 2015; potapov et al., 2012; rincón ruiz et al., 2013; stevens et al., 2011) and on changes of land use and land cover (36%), mainly in the biomes of tropical rainforest, the monsoon forest / dry forest, montane forest, and tree savanna (e.g., bjorgo, 1999; enaruvbe, 2019; murad and pearse, 2018; petit et al., 2001; rincón ruiz et al., 2013; sánchez-cuervo and aide, 2013). the analysis of abandonment of agricultural lands (8%) (e.g., gorsevski et al., 2012; hagenlocher et al., 2012; witmer, 2008) is noticeable in the biomes of mediterranean vegetation, the monsoon forest / dry forest, dry steppe, and montane forest (table 8). discussion concerning the relationship between rs analysis and geographical location of areas affected by armed conflicts, we can infer that the distribution of the rs articles is mainly located near equatorial line in tropical and monsoon forest areas. this is not because, in general, in these areas, there have been more conflicts, since it is not entirely true, indeed many armed conflicts have occurred in temperate, or desert areas such as the caucasus, the balkans, syria, yemen, iraq, turkey, and afghanistan, where the use of rs to assess the impact on the environment has been considerably less. comparing figure 3 to any armed conflict map in the world will show that the pattern is not the same. we can consider that the high number of investigations that use rs methods in equatorial zones compared to other biomes is mainly due to a set of factors. the reasons that we infer are, the long duration average of conflicts in these areas, the type of armed conflict, many of them guerrilla wars and internal conflicts on a smaller intensity of bombings and direct confrontations, but with a greater generation of displaced persons and fatalities. furthermore, the fragility and vulnerability of tropical ecosystems and the high forest density makes land-use and land-cover changes and deforestation more evident. as well in the tropical rainforest, there is a considerable number of collateral affectations such as illicit crops, illegal logging and, illegal mining. additionally, there is a higher presence of population forced to migrate and settle in refugee camps, the limited attention to this population, which in turn generates higher demand for natural resources and greater environmental damage. the difficulty of physically approaching in situ evaluation to these areas makes the use of rs methods more frequently in tropical biomes. 10 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. we found that 64% of the documents analyzed used more than one sensor as a source of satellite imagery. this is because in many cases; it is required to complement the information required for the analysis, the use of more than one sensor. the main reasons are the gaps in temporal availability, availability of high-resolution images, availability of cloud-free imagery and, the availability of specialized satellite imagery data in a particular sector, especially for multivariate rs analysis. the most significant findings of the use of satellite imagery sensors are concentrated in the use of moderate resolution sensors (10-120 m). mainly landsat 4-5 tm and landsat 7 etm+ were the used to study affectations in the biomes of tropical rainforest, montane forest, table 7 relationship between biomes and causes generated by armed conflict cause vs biome t e m p e ra te b ro a d le a f fo re st s u b tr o p ic a l r a in fo re st m e d it e rr a n e a n v e g e ta ti o n m o n so o n f o re st / d ry f o re st x e ri c s h ru b la n d d ry s te p p e s e m ia ri d d e se rt g ra ss s a v a n n a t re e s a v a n n a s u b tr o p ic a l d ry fo re st t ro p ic a l r a in fo re st a lp in e t u n d ra m o n ta n e f o re st t o ta l direct bombing 4 2 3 1 3 2 1 16 direct confrontation / militar infrastructure 1 1 5 1 2 1 2 7 1 2 23 landmines 1 1 1 1 4 indirect forced migration (camp refugees) 1 1 6 4 5 2 12 1 5 37 non-forced migration (colonization) 2 5 2 9 mining 3 1 5 2 11 illegal crops 3 1 1 1 1 4 2 4 17 agriculture 3 1 1 1 7 2 5 20 cattle ranching 1 1 1 1 1 5 2 4 16 timber 1 1 4 2 8 fires 1 1 2 total 5 1 5 27 3 5 5 6 11 5 53 8 29 163 table 8 relationship between biomes and consequences of the armed conflict consequence vs biome t e m p e ra te b ro a d le a f fo re st s u b tr o p ic a l r a in fo re st m e d it e rr a n e a n v e g e ta ti o n m o n so o n f o re st / d ry f o re st x e ri c s h ru b la n d d ry s te p p e s e m ia ri d d e se rt g ra ss s a v a n n a t re e s a v a n n a s u b tr o p ic a l d ry fo re st t ro p ic a l r a in fo re st a lp in e t u n d ra m o n ta n e f o re st t o ta l deforestation 2 1 14 1 2 5 7 2 20 4 11 69 forestation 1 1 1 3 desertification / land degradation 1 1 1 1 1 5 land use / land cover changes 2 2 10 1 2 3 3 4 4 13 3 7 54 mine craters 2 2 militar infrastructure 1 1 1 2 5 abandonment of agricultural lands 2 2 1 2 1 1 1 2 12 groundwater pollution 1 1 2 total 7 1 4 29 3 6 4 10 15 6 37 8 22 152 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. 11 monsoon forest/dry forest and to a lesser extent in the biomes of grass savanna and tree savanna. they cover principally the medium-scale (1000-9999 km2) and the small scale (10,000-99,999 km2). this is due not only to a single cause but to a set of reasons, such as the higher temporary availability of recurrent and high-quality satellite images. furthermore, due to the possibility of finding a larger quantity of images with a low level of cloud cover. another possible cause closely related to the analysis of the consequences is because, for the analysis of vegetation cover of these types of biomes, the size of the scale used does not require a very high level of resolution. finally, another reason is the ease of acquiring this imagery data set due to the public domain character of these sensors (fig. 6 and table 4). imagery preprocessing is a mandatory step in the rs analysis. in the case of tropical biomes, the availability of cloud-free cover images is more difficult to acquire because mostly, these biomes present long rainy seasons throughout the year. it means that the use of calibration correctors and haze removals techniques such as toa, toc, and atcor-2, gain importance as an imperative process, especially in deforestation, land-use, and land cover changes analysis. nevertheless, just a few studies mentioned explicitly the utilization of which type of preprocessing methods used. unfortunately, the acquired data is not enough representative to produce significant conclusions. ndvi can be inferred as the most common method used to classify covers. mainly because of a series of factors such as high compatibility with several types of satellite sensors (mainly landsat), the simplicity of the algorithm, and its capacity to distinguish vegetated areas from other surface types. this is especially noticeable in biomes with a large presence of perennial vegetation as the tropical rainforest. ndvi also has the utility of reducing the size of the data to be managed by a factor 2 (or more), since it changes the two spectral bands by a single new. a relevant finding is a notable relationship between indirect causes and to a lesser extent direct causes with the use of rs in biomes such as tropical rainforests and monsoon forests. indirect causes such as forced migration generate large refugee camps and to a lesser amount, no-forced migration generates processes of colonization of previously virgin areas and in rare cases, the conflict generates protected lands (forestation). mining, agriculture, logging, and livestock have also been studied to a certain degree in tropical biomes by rs methods. direct confrontation and military infrastructure also have a significant but not superlative impact on tropical forests. illicit crops, forced migration, and agriculture heavily affect mountain forests. the monsoon forest/dry forest has been most affected by military infrastructure, direct confrontation, and bombing. the main cause of the damage to the tree savanna and grass savanna in sub saharan africa is forced migration, generating large refugee camps and changes in land use. regarding the findings of analyzed consequences in the environment, deforestation and secondly the land -use changes are the most analyzed impacts, mainly in the following high biodiversity biomes; tropical forests, mountain forests, monsoon forest/dry forest, and less studied in tree savanna and grass savanna biomes (fig. 6). some barriers and boundaries tha t we had during the research were, that despite finding a considerable amount of studies that address the issue of conflict and environment, there is not a very large number of documents that have addressed this problem using rs methods. in those that used rs, it was not easy to identify the type of biome analyzed since they often focus more on country boundaries than on biomes, and these are considered mostly in general rather than fig. 6 relationship between satellite sensor, causes, consequences and biome 12 mendez and valánszki 2020 / journal of environmental geography 13 (3–4), 1–14. specific. likewise, biome boundaries are not only different from country boundaries but are much more difficult to delimit since in most cases, there are biological transition zones between one biome and another, which is why it is very common to find that each armed conflict affects more than one type of biome (uriarte et al., 2010). this is especially noticeable in colombia, since, due to its particular geographical conditions, in a relatively small area, six different biomes can be differentiated. some works used rs to assess ecological and wildlife consequences or to identify human populations at risk, but these lines of research are beyond the scope of this analysis and therefore were not considered for this investigation. we would like to highlight that the scope of this paper is to frame the state of the art on the relations hip between armed conflicts, the environment, and their study methods. in order to, from this first step, lay the foundations for more exhaustive research that will allow a better understanding of the complex relationship between armed conflicts and their impact on the environment. this will allow subsequent researches to create more precise and complete methods of evaluation, diagnosis, and possible restoration of the damaged environment. given the recent and current peace processes, it would be especially interesting to continue tracking deforestation, land-use changes, and other consequences in those countries by adding more data and study parameters. tracking of year -to-year changes using high-resolution data would be notably useful for correlating specific economic and political conditions with landscape, land use, and deforestation rates and distributions. conclusion the observations and results presented here are considered applicable and relevant for the analysis of rs data related to studying the iss ue between armed conflict and environment, which is not applicable nor considered generally true for armed conflicts itself. the impacts of warfare on environments are diverse and complex; increase mainly deforestation and land use changes. over 79% of the rs studies of major armed conflicts between 1980 and 2019 occurred within the torrid area, biomes located near the equatorial line; more than 64% took place directly within high biodiversity hotspot areas. less than one third of the 34 recognized hotspots escaped from significant conflict during this period and most suffered repeated episodes of violence. this pattern has been remarkably consistent over these 3 decades. the most affected studied biome is tropical rainforest; this biome may be found in sout heast asia, central africa, and amazonia, covering about 12% of earth's land surface (excluding ice-covered areas such as antarctica). the largest impact studied using rs in the biomes is deforestation with 45% of the studies, and secondly the land-use change with one-third of the studies. the greatest cause of affectation is indirect causes (70%) such as forced and unforced migration, illicit crops, mining, agriculture, and cattle ranching. this can be explained because migrant populations are larger in these zones, demanding large resources for movement as well as settlement. in the case of colombia and afghanistan, illicit crops are a major factor in deforestation and land -use change. consequences of armed conflicts such as deforestation and land-use change are the most predominant effects in tropical biomes (tropical rainforest, montane forest, monsoon forest/dry forest). the present research could be useful as a base for future investigations in specific areas in order to analyze armed conflicts and their effect on the landscape. moreover, it could work as a guideline to make decisions regarding which rs methods and satellite sensors might be used, based on biomes, scales, causes, and consequences. indeed, the present document provides a background and a starting point that allows for a more extensive analysis of the warfare-environment affair. in the future, we will study the case of the national parks of colombia affected by the internal armed conflict, taking as a sample area the "sumapaz np". references abuelgasim, a.a., ross, w.d., 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(eds.) the sage handbook of remote sensing. 55 city road, london: sage publications, inc. doi: 10.4135/9780857021052.n16 van etten, j., jongerden, j., de vos, h.j., klaasse, a., van hoeve e.c.e. 2008. environmental destruction as a counterinsurgency strategy in the kurdistan region of turkey. geoforum 39 (5), 1786–1797. doi: 10.1016/j.geoforum.2008.05.001 witmer, f.d.w. 2008. detecting war‐induced abandoned agricultural land in northeast bosnia using multispectral, multitemporal landsat tm imagery. international journal of remote sensing 29 (13), 3805–3831. doi: 10.1080/01431160801891879 witmer, f.d.w. 2015. remote sensing of violent conflict: eyes from above. international journal of remote sensing 36 (9), 2326– 2352. doi: 10.1080/01431161.2015.1035412 http://www.fao.org/fileadmin/user_upload/%20rome2007/docs/arab_environment_future_challenges.pdf http://www.fao.org/fileadmin/user_upload/%20rome2007/docs/arab_environment_future_challenges.pdf introduction armed conflict causes and effects on the environment satellite imagery and armed conflicts aim materials and methods results armed conflict & remote sensing assessment by biomes relationship between satellite imagery sensors and biomes relationship between satellite imagery sensors and study area scale preprocessing of satellite imagery sensors satellite imagery sensors and imagery classification relationship between biomes and causes generated by armed conflicts. relationship between biomes and consequences of the armed conflicts discussion conclusion references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iv. no. 1-4. pp. 11-17 discharge calculation of paleochannels on the alluvial fan of the maros river, hungary sümeghy, b. 1 – kiss, t. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract the aim of the study was to identify the abandoned channels on the alluvial fan of the maros river and to calculate their paleodischarge. as the first step of the investigation regional equations had to be made for discharge calculations based on the earliest available discharge data for the rivers of the tisza catchment in hungary. equations between discharge and channel parameters were created with high correlation coefficient. then the paleochannels were identified on the hungarian part of the alluvial fan. the paleochannel generations are located in continuous zones with well defined boundaries. the density of the abandoned channels varies on the alluvial fan, as some areas densely covered by channels and on other areas almost free of paleochannels. braided, meandering and misfit channels were separated, but only the morphometry of the meandering and misfit channels were measured (width, ratio of curvature, half-wavelength and cord-length). based on these morphometric parameters and the discharge equations the mean discharge of the channels was calculated. the greatest discharge was around 6300 m 3 /s while the smallest was 31 m 3 /s. however, several abandoned meandering channels had slightly greater bankfull discharge (700-900 m 3 /s) as the present-day maros river. introduction the paleoclimate reconstructions have an important role in the analyses of the paleoenvironmental events. there are several methods to complete it; most of them aim to determine the precipitation and the temperature. for example the former precipitation and runoff conditions could be reconstructed by calculating paleodischarge data (stein et al. 2004, scheurle et al. 2005, carson – munroe 2005, saenger et al. 2006). besides, these data could be used to reconstruct the magnitude and frequency of floods in the past and to evaluate the amplitude of the present-day floods (thorndycraft et al. 2005, benito – thorndycraft 2005). the paleohydrological data can give useful contribution to study climate change tendencies (carson – munroe 2005). there are several methods to examine and reconstruct the hydrological conditions of the past. some studies use proxy data, for example the ratio of stable oxygen isotope or the rate of the high-resolution magnetic susceptibility. for example scheurle et al. (2005) used paleo-oceanographic proxy data of stable oxygen isotopes to determine paleodischarge of the rivers. they analysed the rate of isotopes in calcareous shells of marine animals, because the rate of isotopes correlates with salinity, thus the ratio of saltyand freshwater (paleodischarge) were estimated using the known sea-level changes. saenger et al. (2006) applied the same method, but they have also modelled the precipitation conditions of the drainage area. sedimentological, geochemical and micropaleontological proxy data of surface sediments also allow to characterise the climate. high-resolution magnetic susceptibility record was used to estimate sediment fluxes and their relationship to paleo-environmental changes. the variability of sediment fluxes during the holocene can be related to the changes in river discharge and coastal erosion input (stein et al. 2004). slack-water deposits were also analysed (thorndycraft et al. 2005, benito and thorndycraft 2005) to study the floods of the last century and to reconstruct the main flood events. the growing amount of flood deposits was in connection with rising flood-level, which is was dated by radiocarbon measurements. carson and munroe (2005) applied dendrohydrology to reconstruct mean annual discharge and precipitation data. the width of an annual tree ring reflects the yearly hydrological conditions and refers to the near-surface temperature, evapo-transpiration and precipitation (werritty and leys 2001). sidorchuk and borisova (2000) used paleogeographical analogues to determine paleohydrological and paleoclimatic parameters. the paleogeographical analogue is based on two assumptions: (1) similar hydrological regimes were characteristic for the paleorivers in similar paleolandscapes; (2) the hydrological regime of a paleoriver within some paleolandscape would be similar to that of a present-day river in the same type of landscape. thus, to determine hydrological parameters of paleorivers and the simultaneous climatic conditions a present-day river must be found which is very similar – every parameters and locations – to the paleoriver. lauriol et al. (2002) used fluvial morphology and deposits to conclude paleoclimatic conditions, because the changes in climatic conditions will be reflected by the discharge and they can affect channel parameters (in this case cross-sections were used to determine paleodischarge). since there is a close relation between discharge and different channel parameters, a wide range of paleodischarge calculations exist. for example sylvia and galloway (2006) reconstructed late pleistocene discharge, their calculation was based on radius of curvature, wavelength and some other channel dimensions. 12 sümeghy, b. – kiss, t joeg vi/1-4 in the carpathian basin gábris (1986, 1995), timár and gábris (2008) made paleodischarge calculations to study holocene climate change and the discharge of scourchannels. the relationship between meander wavelength and the characteristic discharge values was defined. williams (1984) emphasized the regional validity of the equations, thus the equations can be used just in the same geographical environment and for the same river size as the equations based on. according to ward et al. (2007) the climate is a driving force in the hydrological system, therefore the smallest climate change can have significant effect on hydrological processes, including changes in the volume and temporal pattern of discharge. ward et al. (2007) made climaticand hydrological models to simulate paleodischarge of holocene rivers using recent discharge data. the estimated paleodischarge data were close to the data created by the climateand hydrological model, and the discharge change closely followed the latitudinal and seasonal variations in insolation. the aim of the present study is to identify the abandoned channels on the hungarian part of the alluvial fan of the maros river and to determine their paleodischarge. our secondary aims are to determine the river course changes based on the morphometry and spatial distribution of the channels and to create regional equations between the discharge values and morphometric parameters. the paleodischarge data could be important to forecast the maximum flood discharge, as increasing magnitude and frequency of floods are very important environmental hazards in hungary. study area our study area is the alluvial fan of the maros river, which located in the south-east part of the great hungarian plain. the radius of the alluvial fan is 80-100 km (fig. 1). the alluvial fan is shared by hungary, romania and serbia. in this study only the hungarian part of the alluvial fan (3640 km 2 ) is studied because of the limited availability the maps from the surrounding countries. according to mike (1991) the evolution of the alluvial fan started in the late pliocene, however, according to molnár (2007) it started in the early pleistocene based on the sedimentary sequences of the deposits of the alluvial fan. according to andó (1976) and borsy (1989) the formation of the youngest part of alluvial fan started in the late pleistocene or in the early holocene. nádor et al. (2007) found that the maros river turned to its present direction during the middle or late holocene, as it is reflected by the middle gravel layer in the three layers which can be found in the maros river alluvial fan’s sedimentary structure. during the late pleistocene and holocene the maros river changed its flow direction on the alluvial fan frequently driven by the rising or sinking of the sur fig. 1 location of the alluvial fan of the maros river (source: srtm, resolution 90 m) joeg vi/1-4 discharge calculation of paleochannels on the alluvial fan of the maros river, hungary 13 rounding areas (mike 1975, andó 2002). according to márton (1914) the maros had no well-defined channel until the pleistocene, as it was split into several secondary channels. the frequent flow-direction changes were also described by andó (2002), who mentioned four main course directions during the pleistocene. according to mike (1991) the holocene maros river changed channels on the alluvial fan frequently, but almost in each case at first it turned to north-east than towards south. however, none of these changes had real scientific evidences, as no precise age determination or sedimentary record exists. methods creating paleodischarge equations the paleodischarge equations are based on contemporary hydrological and morphometric data of the lowland rivers on the great hungarian plain. determining bankfull discharge data the first precise discharge data for the catchment of the tisza are available from the 1930’s, thus they were used because at that time the channel was has not been distorted yet by revetments (though cut-off were already made; kiss et al. 2008). the difficulties of the calculations were that (1) in the 1930’s discharge measurements were not systematic, they were made mostly in extreme hydrological conditions like at floods or low water stages; and (2) several times the discharge were just calculated from the water level. the bankfull discharge was determined at 18 rivers gauging stations (7 gauging stations on the tisza river and 11 on the tributaries: fig. 2). in order to determine the bankfull discharge the contemporary crosssections of the channel was also used. according to dury (1961) the bankfull discharge is the most hydrological parameter in connection which the morphometry of the channel. therefore those horizontal morphometric parameters were measured which are in connection with the bankfull discharge. determining the morphometric parameters of the channel the channel parameters were measured on the iii. military survey maps (1882-1884), which were made at the time of the river regulations. for the measurements 5 km long river sections at each gauging stations were analysed. the bank-line and the centre-line of the sections were digitalised and the channel width (w), radius of curvature (rc), half-wavelength (l) and cord-length (h) were measured. according to laczay (1982) the proportion of halfwavelength and cord-length (l/h) refers to the development phase of the meander, thus the bends can be classified as pseudo-bend, underdeveloped, developed, welldeveloped and close-to-cut-off meander. from these classes the developed and well-developed meanders are the best to calculate the relationship between morphometric parameters and discharge (gábris 1986). therefore, during the paleodischarge calculations only the developed and well-developed meanders were used, therefore 54 meanders were chosen from the 90 curves. creating equations between discharge and channel parameters the equations were created using the water discharge bankfull data of the 1930’s and the determined horizontal channel parameters of the third military survey. the aim was to create equations with high correlation coefficient. using these equations the paleodischarge of the paleochannels identified on the alluvial fan was determined. fig. 2 the discharge data of 18 gauging stations were used and the meander parameters of the 5 km long river sections 14 sümeghy, b. – kiss, t joeg vi/1-4 3.2. identification of paleochannels to identify the abandoned channels on the alluvial fan 1:10.000 scale topographical maps and srtm images (shuttle radar topography mission with 90 m resolution) were used. under arcgis 10 software the banklines of the paleochannels were digitalised. the different channel pattern types (braided, meandering and misfit) and channel generations were separated. on the identified meandering channels the horizontal morphometric parameters (w, rc, l and h) were measured. the values of these parameters were substituted into the equations, thus the paleodischarge of the paleochannels was determined. results and discussion creating paleodischarge equations exponential and polynomial relationships were supposed between the bankfull discharge data from the 1930’s and the horizontal channel parameters of the developed or well-developed type of meanders. equations with the highest possible correlation coefficient were created (table 1). the applicability range suggests the limits of the usage of the equations. distribution and morphology of paleochannels the density of the paleochannels on the surface of the alluvial fan varies (fig. 3). some areas are densely covered by paleochannels (17.7%) and in some areas they rarely appear (2.4%). the abandoned channels show a table 1 relationships between discharge and channel parameters and their applicability range channel parameter equation and correlation coefficient applicability range width (w) q = 0.0001*w 3.2111 r 2 = 0.7671 55 – 185 m radius of curvature (rc) q = 0.0008*rc 2 +4.1692*rc – 226.13 r 2 = 0.6983 29 – 509 m half-wavelength (l) q = 0.0003*l 2 + 0.344*l – 81.329 r 2 = 0.7235 472 – 2538 m chord-length (h) q = 0.0015*h 2 + 0.0647*h – 31.762 r 2 = 0.7888 307 – 1197 m the cord-length (h) and the width of the channel (w) show the highest correlation with bankfull discharge. however width characterizes only just one point of the meander and it depends on the channel material, just like the radius of curvature. fig. 3 abandoned channels and their zones on the maros river alluvial fan joeg vi/1-4 discharge calculation of paleochannels on the alluvial fan of the maros river, hungary 15 typical pattern, as they appear in almost continuous zones with well-defined boundaries. the channel pattern, the channel density and the ratio of curvature was the basis if the identification of the zones. these zones run from east to west in an anticlockwise direction. the mean length of the zones is 42 km and their width changes between 4.1 and 8.7 km (table 2). table 2 some typical parameters of the paleochannel zones on the maros river alluvial fan surface zone channel channel pattern no. area (km 2 ) length (km) width (km) radius of curvature (m) min max mean min max mean i (younger) 296 51 2.1 8.2 5.1 62 186 109 misfit i (older) 283 712 405 meandering ii 99 18 1.2 9.8 5.5 braided iii/a 164 27 1.8 10.6 6.2 braided iii/b 146 24 2.7 9.5 6.1 braided iv 164 27 2.6 11.2 6.9 96 589 284 meandering v 207 38 2.7 8.4 5.5 61 94 70 meandering/misfit vi 99 27 2.8 5.3 4.1 226 756 505 meandering vii 200 39 2.0 7.6 4.8 braided viii 187 25 4.3 13.1 8.7 354 1182 656 meandering ix 474 70 2.6 13.6 8.1 451 2299 1119 braided / meandering x 452 77 2.5 8.6 5.5 braided xi 348 80 1.5 10.2 5.8 256 542 384 meandering xii 213 37 3.2 10.6 6.9 braided xiii 375 51 2.0 12.3 7.1 437 532 485 meandering fig. 4 (a) transformation of a braided channel into meandering pattern (zone ix), and (b-c) misfit channels from zones v and i 16 sümeghy, b. – kiss, t joeg vi/1-4 determining paleodischarge for the meandering paleochannels of the alluvial fan applying the equations above, the paleodischarge of the abandoned meandering channels was calculated based on their horizontal morphometric parameters (table 3). in the zones no. ii-iii, vii, x and xii the pattern of the paleochannel is braided, thus the equations can not be applied for them. there is also an applicability range limit for the equations (table 1), though smaller and greater paleomeanders were also identified. however, the equations were used to calculate their paleodischarge, but it have to be noted that these data have the greatest error. to determine smaller and higher water discharges we have to extend the study on rivers with higher bankfull discharge, however it means that other rivers than of the tisza’s catchment have to be analysed from the carpathian basin. on the surface of the maros alluvial fan several channels were found which have slightly greater bankfull discharge like the present-day maros river (680 m 3 /s; sipos 2004). the meandering channel in zone ix had the greatest mean bankfull discharge (ca. 6300 m 3 /s), which is much higher than the present-day bankfull discharge of the tisza (3630 m 3 /s; fiala et al. 2006) or the danube (6550 m 3 /s, at mohács, based on the data of hydrographical annals 1970-2000). however this data is beyond of the applicability range of the equations. the determination of the age of this paleochannel will be very important, as the environmental circumstances of such high discharges could be interesting in further research. conclusions the aim of the present study was to indentify the abandoned channels on the alluvial fan of the maros river and to calculate their paleodischarge based on newly developed equations between bankfull discharge and horizontal channel parameters. the abandoned channels appear in zones. in the western part of the alluvial fan mostly meandering channels were identified, while on the eastern part the braided channels are typical. on the northern part of the alluvial fan the braided and the meandering patterns are varying. other channels are misfit, suggesting radical discharge decrease. the correlation coefficients (r 2 =0.7-0.8) of the created equations are relatively high, but it could be increased by enlargement of the data base. the highest correlation was found in connection with chord-length, which value characterizes the whole curve. the bankfull discharge of the braided paleochannels could not be calculated using the created equations, therefore it was calculated just for the meanders. several abandoned meandering channels had slightly greater bankfull discharge (840 m 3 /s) as the present-day maros river, though some had very small (31 m 3 /s) and other quite great values (6300 m 3 /s), reflecting drastic environmental (i.e. precipitation and runoff) changes during their activity. in the middle part of the alluvial fan (zone ix) the paleochannels had the highest discharge data, while the north and south direction from it, the value of the discharge is gradually decreasing. the results could be used in future flood protection, because it pointed on the fact that extreme discharge conditions could appear in the system of the maros river. besides, the created regional equations could be used in table 3 the calculated bankfull discharges of the paleochannel zones (grey numbers are beyond the application limit of the equations) zone bankfull discharge minimum maximum mean i (younger: misfit) 32 275 118 i (older: meandering) 656 3683 1338 iv 104 1870 637 v 13 76 31 vi 320 2833 1591 viii 605 3414 637 ix 1682 12675 6300 xi 485 1429 840 xiii 1155 2515 1642 joeg vi/1-4 discharge calculation of paleochannels on the alluvial fan of the maros river, hungary 17 river restoration projects, where the design of appropriate channels parameters is the key-point of each project. acknowledgement the research was supported by the huro/0901/266/2.2.2/01 project. references andó m. 1976. groundwater-geographical and hydrogeological conditions of the talus system of the river maros. acta geographica szegediensis 16: 39-57 andó m. 2002. a tisza vízrendszer hidrogeográfiája. szeged: szegedi tudományegyetem, tfgt. 89-107 borsy z. 1989. az alföld hordalékkúpjának negyedidőszaki fejlődéstörténete. földrajzi értesítő 38/3-4: 211-224 benito g. – thorndycraft v. r. 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(eds.) vízrajzi atlasz sorozat 19: maros. budapest: vituki. 14-18 mike k. 1991. magyarország ősvízrajza és felszíni vizeinek története. budapest: aqua kiadó. 361-577 molnár b. 2007. a maros folyó kialakulása és vízgyűjtő területének földtani felépítése. hidrológiai közlöny 87/2: 27-30 nádor a. – thamó-bozsó e. – magyari á. – babinszki e. 2007. fluvial responses to tectonics and climate change during the late weichselian in the eastern part of the pannonian basin (hungary). sedimentary geology 202: 174-192 saenger c. – cronin t. – thunell r. – vann c. 2006. modelling river discharge and precipitation from estuarine salinity in the northern chesapeake bay: application to holocene palaeoclimate. the holocene 16/4: 467-477 scheurle c. – hebbeln d. – jones p. 2005. an 800-year reconstruction of elbe river discharge and german bight seasurface salinity. the holocene 15/3: 429-434 sidorchuk a. y. – borisova o. k. 2000. method of paleogeographical analogues in paleohydrological reconstructions. quaternary international 72: 95-106 sipos gy. 2004. medermintázat és zátonyképződés homokos medrű síksági folyószakaszon (maros 31-50 fkm). geográfus doktoranduszok viii. országos konferenciája, szeged. cd. isbn: 963-482-687-3 stein r. – dittmers k. – fahl k. – kraus m. – matthiessen j. – niessen f. – pirrung m. – polyakova y. – schoster f. – steinke t. – fütterer d. k. 2004. arctic (palaeo) river discharge and environmental change: evidence from the holocene kara sea sedimentary record. quaternary science reviews 23: 1485-1511 sylvia d. a. – galloway w. e. 2006. morphology and stratigraphy of the late quaternary lower brazos valley: implications for paleo-climate, discharge and sediment delivery. sedimentary geology 190: 159-175 thorndycraft v. r. – benito g. – rico m. – sopena a. – sánchez-moya y. – casas a. 2005. a long-term flood discharge record derived from slackwater flood deposits of the llobregat river, ne spain. journal of hydrology 313: 16–31 timár g. – gábris gy. 2008. estimation of water conductivity of natural flood channels on the tisza floodplain, the great hungarian plan. geomorphology 98: 250-261 ward p. j. – aerts j. c. – moel h. – renssen h. 2007. verification of a coupled climate-hydrological model against holocene palaeohydrological records. global and planetary change 57: 283-300 werritty a. – leys k. f. 2001. the sensitivity of scottish rivers and upland valley floors to recent environmental change. catena 42: 251-273 williams g. p. 1984. paleohydrological equations for rivers. in: costa j. e. – fleisher p. j. (eds.) developments and applications of geomorphology. berlin: springer verlag. 343367 physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. iii. no. 1-4. pp. 25-30 characteristics of the flow regime along the regulated tisza river reach downstream of tiszafüred bezdán, m. 1 1 viziterv consult kft, budapest, hungary abstract in this paper, an attempt is presented at clearing the reasons of some uncommon flow phenomena observed over the tisza reach downstream of tiszafüred, and at pointing to the practical significance of the results obtained. over six hundred thousand daily stage data were selected from the more than six million (!) water level data, registered from 1876 to 2009 (on the gauges between tiszafüred and novi bečej (törökbecse)). taking the data of ground water wells into consideration, the conclusions arrived at are believed to be of interest to theoretical fluvial hydrologists, yet also to river engineers engaged in designing and operating (when needed) flood control schemes. key words: low-water, high-water, ground water, hysteresis function, water level drop, backwater, barrage, permanence introduction the comprehensive reclamation project conceived by pál vásárhelyi and implemented under the management of károly herrich has changed flow conditions of the river tisza and those of the tributaries substantially. flood peaks rose by 3 to 4, and low waters dropped by 2 to 3 metres in the bed, which was shortened by 32 % of the original length. the steeper slope has increased the average flow velocities river = 1.26 times at medium stages. the coincidence pattern and extent of interaction with the tributaries have also undergone changes (vágás 2007). owing to drainage accelerated by roughly 26% in the main river and to the loss of storage space in the severed oxbows (vázsonyi 1973), the spring and early summer flood waves travelled downriver faster and were followed by longer arid summers and longer low water periods. after up to 20 to 40 rainless days, most of the flow consists of groundwater drained by the river (szalay 2000). groundwater is depleted further by withdrawals for human uses (csatári et al. 2001, völgyesi 2005, 2009), thus lowering the ground water table (rakonczai 2006). the project has started hydrologic processes, which conflicted with traditional laws of fluvial engineering, and which failed to explain several of the phenomena and processes actually observed. these include the dropping low-water levels (iványi 1948, dunka et al. 1996, konecsny 2010), the changes in the ground water table and the flow regime of rivers (rónai 1985, tóth 1995, tóth – almási 2001, rakonczai 2001, bozán – körösparti 2005, völgyesi 2005, 2009, pálfai 2005, 2011, szalai – lakatos 2007, marton 2010), the rising highwater water levels and the effects of the barrages (koncz 1999, stegăroiu 1999, schmutz et al. 1995, giesecke – mosonyi 2005). more recent studies have attributed these to changes in the state of the flood bed flanked by the levees (silting and vegetation growth) and in the channel geometry (nagy et al. 2001, schweitzer 2001, gábris et al. 2002, sándor – kiss 2006). without intending to question the potential local significance of these effects, the hydrological phenomena dealt with below (viz., flattening flow profiles, effect of barrages and the actual hydrologic interactions between the recipient and the tributary rivers, as well as the ground water) are considered more general and substantial in nature. flood waves starting form the upstream tisza have been observed repeatedly to overtake each other before entering the middle reach. some of such flood waves have been observed more recently to split again on the lower reach. backwater, respectively drawdown, by the major recipients has been offered as explanation for these phenomena (vágás 1982). the flood waves entering from the tributaries maros and hármas-körös may coincide with rising or falling stages in the recipient tisza river and raise, or lower the peaks of the latter. the actual stage in the danube, the ultimate recipient, may also back up, or draw down the tisza water level and even start a peak spreading upstream in the tisza river. such random flood waves may become perceptible as the cause of important changes in the flow regime in the tisza river, owing to the extremely flat slope of the latter. the discharge measurements of growing frequency over the past decades have revealed that together with the gauge reading, the slope of the surface profile must also be allowed for when estimating the actual discharge (dombrádi 2004). the 133 years long record of flows and floods in the river tisza has revealed that the normal velocity and direction of flow differ markedly from the velocity and direction of the flow registered during the flood peaks (vágás – simády 1983). the flow velocity is determined normally by the discharge, bedand surface slope conditions of the river in accordance with the conventional laws of hydraulics, whereas the velocity of the flood peaks depends highly on the actual backwater and/or drawdown caused by the tributaries, or the main recipient (the danube). the peak stage may spread upstream against the 26 bezdán, m. joeg iii/1-4 direction of flow over long river sections. flood waves starting over the upper reach have been observed repeatedly to flatten over the middle, or lower reach, before entering the danube. although more in-depth studies on the aforementioned phenomena have been started but recently, their correlation seems obvious. the general opinion of huszár (1985), bogdánfy (1906), erdős (1920), tellyesniczky (1923), korbély (1909), iványi (1948), lászlóffy (1982), vágás and simády (1983) was that not all flood waves travelling down the river tisza, but only some of them peaked earlier at upper gauging stations than one of the downstream ones, and ended “regularly” at the mouth to the danube. an appreciable number of tisza floods were affected on one of the middle or lower sections (not necessarily the same in every case) by backwater of a flood on the danube or one of the tisza tributaries – especially the rivers maros or körös rivers, or drawdown in the case of their recession, so that the peak occurred earlier at the lower gauging station than at one of the upstream ones. a hydrological phenomenon observed long ago on the tisza river is the hysteresis loop, viz., a curve displaying the discharge of a flood wave versus the corresponding stage (bogdán-ffy 1906, korbély 1937, németh 1954). its substantial feature is a peak stage residing over the same section for a longer period of time (several days). as a consequence of these irregularities the relationships based on steady flow velocity and surface slope are limited in their validity and usefulness. objectives the aim was to identify and offer theoretical and practical solutions to issues as yet not fully cleared in the tisza river section downstream of tiszafüred. over six hundred thousand daily stage data were selected from the over six million water levels registered from 1876 to 2009 (on the gauges between tiszafüred and novi bečej (törökbecse). the more specific objective was to correlate streamflow and progress of flood waves, to analyse their likelihood along the river section and in time, their statistical characteristics and to discover the hydrological and geographical reasons leading to their occurrence in the tisza section downstream of tiszafüred and to identify those considered extraordinary relative to other rivers. an attempt was made at shedding new light on areas of scientific interest believed to merit further study in order to improve flood control measures by drawing on lessons learned during floods of recent decades, and made possible by latest advances in computerised analysis. the impact of the tributaries and the main recipient – the danube – on the tisza was the most important question, which has not received adequate attention thus far. surface profiles in river networks comprising tributaries and recipients are prominent areas in this respect. in such networks the distinction between the velocity of river flow and that of the flood peak is believed important enough to study more in depth. the phenomenon of flood peaks spreading opposite to the direction of flow is believed unique in global fluvial hydrology. accelerated drainage in the wake of the tisza valley reclamation project has depleted the water resources also along the tisza reach downstream of tiszafüred. the extent thereof in periods of low precipitation was demonstrated on the basis of the data of ground water level detection that had started in the beginning of 1930’s. weirs were studied for their impact on groundwater, river flow and water regime. methods and area of analysis tisza water levels registered daily after regulation from 1876 up to 2009 on the gauging stations between tiszafüred and novi bečej (törökbecse) were processed. surface slopes were determined as the difference in water levels registered simultaneously on two adjacent stations and divided by the distance between the respective stations. the surface slopes determined in this way were then evaluated statistically. the following river sections were studied: tiszafüred, taksony, tiszabő, szolnok, martfű, tiszaug, mindszent, csongrád, algyő, szeged in hungary, and novi kneževac (törökkanizsa), senta (zenta), novi bečej (törökbecse) in serbia. the gauge readings were divided into metre-ranges and the slopes obtained were entered in the appropriate range. the 133 years long record was also subdivided into periods. the daily surface profiles of the tisza were plotted and the annual lowest-, meanand highest stages were identified. any change over time in these water levels was examined for events and interference with the life of the river, which have actually or potentially affected the flow regime. the annual duration of water levels below the gauge “0” and above the “600 cm mark” was noted, as well as the actual duration in the higher-than 600 cm range of the major flood waves. the flood waves travelling normally downriver, that is peaking successively at each gauging station and showing no backwater evidence were analysed. the temporal changes of the annual low level in the groundwater observation wells were compared to the low stages in the rivers. a few floodloops were plotted making use of the scarce streamflow measurements and the corresponding gauge readings. for the same cases the conventional gauge relation curves were also drawn. joeg iii/1-4 characteristics of the flow regime along the regulated tisza river reach downstream of tiszafüred 27 review of the findings by detailed scrutiny of the over 130 years long record of river stages in conjunction with over 80 years of groundwater readings, with due allowance for human interferences in the catchment, as well as for changes in rainfall pattern, the following conclusions have been arrived at: the major drop of low-water levels over the martfű–mindszent tisza section is attributable to the substantial reduction of the runoff from, and exhaustion of, the storage opportunities in the körös catchment. the major drop has taken place in two steps: in the 1841-1842 lowwater period considered relevant for setting the elevation of the “0”point of the gauges, the combined flow in the three körös branches was large enough to feed the tisza section involved, so that the gauge readings were higher. subsequent developments in the körös catchment have depleted the low-water yield and thus reduced the discharge to the tisza materially. the reduced low-water discharge from the körös catchment has flattened the former bulge on the low-water surface profile on the affected section (fig. 1). the low-water surface profiles react promptly to changes in the tributary discharges. reduced inflow from the körös catchment has reduced the low-water streamflow in the recipient tisza downstream of csongrád. this, in turn, has allowed more pronounced effect of the backwater caused by discharge of the tributary maros. as the consequence thereof, the surface slopes decreased from the maros mouth upstream as far as csongrád. on the other hand, upstream of the körös mouth the surface slope became steeper again, because the low inflow from the körös causes no backwater in the tisza (bezdán 2010a, 2010b). completion of the tiszalök dam in 1957 and of the eastern main canal in 1965 has relieved dry-weather water shortage in the region and raised low-water flows in the river section studied. additional supplies to the region were channelled from the kisköre dam and the western main canal. the low-water surface profiles became even smoother thanks to the backwater of the novi bečej dam (1976). flood waves travel downriver with different surface slopes. the average slopes on the various sections were calculated from widely scattered data. in terms of percentages the differences are formidable and play a significant role in changing the water levels. when compiling stage forecasts, local distribution of rainfalls must also be allowed for (bezdán 2010a, 2010b). except for river sections impounded also at lowwater, surface slopes become steeper with falling depth. at mean water the surface slope is flatter than at low water. the cause of this phenomenon is that downstream of the mouth of a tributary, the discharge thereof is added to that of the recipient tisza, the water level in the latter rises with a steep surface slope. on the other hand, upstream of the mouth the flow in the recipient is backed up, the water level is raised, while the surface slope becomes flatter and may assume even negative values. over the section affected peaking is delayed and an inverted flood loop occurs. such reversed flood loops develop on river section(s) upstream of backwaters. immediately downstream of tributary mouths normal flood loops may be expected. in cases where the backwater effect of the recipient, or a tributary, or a weir extends upstream beyond the mouth of a recipient, the sense of the flood loop downstream of the mouth will depend on the actual discharge of the tributary (bezdán 1997, 1998, 1999, 2008, 2010a, 2010b). fig. 1 surface profiles of lowest low-waters in the years indicated 28 bezdán, m. joeg iii/1-4 over 70% of the tisza flood waves were backed up by one of the tributaries or the danube during the 1876 to 1975 period. more than 90% of the flood waves peaking with stages above the 600 cm range belonged to this category. since the novi bečej dam was commissioned in 1976, backwater has raised 80% of the flood waves and 95% of those with overbank stages. conveyance of virtually all high floods is affected also by the fact that these are under the combined influence of two or more tributaries and since 1976 also of the novi bečej dam. the most often backed up river section in the high-water ranges are those between tiszaug and algyő. since the dams were commissioned, flood waves were backed up repeatedly along these sections. flood waves peaking within the banks in the pre-dams period were backed up by the danube beyond szeged in 25% of the cases, this percentage having grown to 48% since the novi bečej dam started operating. of the overbank floods backed up beyond szeged, 25% were registered before 1976 and 20% thereafter. this information is of paramount interest in forecasting and fighting floods. the number of flood waves peaking in “reversed order” decreases with distance from the river causing them. the number of peaks attributable to the danube backwater decreases with distance from the tisza mouth, but owing to the clearly undistinguishable simultaneous influence of the körös and maros tributaries, the relationship is not a straightforward one. the unbalanced distribution of the occurrence of all “reversed” flood waves may be influenced by the possibility of interference between several gauging stations (bezdán 1999, 2008). owing to backwater from the recipient, some flood peaks occur upstream of the mouth of a tributary. thus 40% of the tisza flood waves since 1876 and peaking at all gauging stations terminated upstream of senta. this figure is 54% for flood waves peaking above the 600 cm mark. since 1976, when the novi bečej dam started operating, 58% of the flood waves terminated at one of the stations upstream of senta, whereas formerly this figure was 28%. of the flood waves peaking in the higher-than 600 cm range those advancing farthest downstream occurred most frequently between the stations martfű and szolnok during the 1876-1975 period. after 1976 most flood waves peaked latest along the martfű, tiszaug and mindszent section. for the apparent “retardation” of the tisza flood waves described by several authors, random changes of the actual hydrologic conditions in the catchment are believed responsible, rather than spontaneous, or artificial hydromorphological changes in the river bed. this information should be remembered when contemplating levee reinforcement projects (bezdán 1999, 2002). during the 1976-2009 period, over the tisza sections influenced by dams and weirs the low-water surface slopes decreased, while their statistical scatter widened. the high-water-slopes, on the other hand, became steeper with a narrower scattering range (bezdán 2010a, 2010b). downstream of the kisköre dam commissioned in 1973 the lowest low-water levels dropped until the year 2009 by more than 100 cm at taskony, 50 cm at tiszabő, 20 cm at szolnok and 10 cm at martfű, parallel thereto, the duration of low water levels has grown. novi bečej (törökbecse) dam commissioned in 1976 has created a backwater reach extending normally upstream to csongrád (in the range of lowest low-waters up to tiszaug) and raising the low-water level at tiszaug by 55 cm, at csongrád by 105 cm, at mindszent by 150 cm, at algyő by 170 cm, at szeged by 200 cm, novi kneževac by 270 cm, at senta by 300 cm, while at the dam itself by 385 cm on the average. this means that at lowest low-water the average readings on the same gauging stations became -240, -135, -25, 50, 70, 140, 205 and 270 cm, respectively. the dam has thus actually eliminated low-waters in its vicinity, reducing flow velocities virtually to zero. releases of low and medium flows are thus completely controlled by the dam. this implies at the same time that the channel along the backwater reach has no influence any more on the flow regime and functions actually as an impounded system, which stores the water until it is released as scheduled by the dam operator (bezdán 1994). upstream of kisköre dam the lowest backwater level has increased by more than one metre since the nineties. silting has raised the lowest backwater by 3050 cm also upstream of novi bečej dam. the water levels at high flows are influenced by the dams and weirs, as well as by the discharges of tributaries. kisköre dam influences the flow regime by the water stored behind it in that any arriving flood wave spills over a raised water level rather than over a low one, changing the original conditions. flood levels may then be raised substantially downstream as far as the southern national boundary, especially in then event of simultaneous flood discharges from the aforementioned two major tributaries (the maros and the three körös branches). at times of major flood waves, the backwater upstream of the novi bečej dam merges the former gauge relation curves as far upstream as tiszaug. traces of the historic gauge relations are difficult to recognise even at times of high maros floods. this means that river flows are controlled by the novi bečej dam also during highwater periods, in that releases depend on the conveying capacity of structure. the arriving flood flows are thus necessarily stored and raise the water level in the limited flood-bed volume enclosed by the flood levees up to the kisköre dam. the rate of release at the mouth depends joeg iii/1-4 characteristics of the flow regime along the regulated tisza river reach downstream of tiszafüred 29 not necessarily on the rate of the original inflow, but on the conveying capacity and hydrologic state of the recipient streambed comprising the dam. during the pre-dam period the traditional gauge relation curves have clearly revealed any backwater and substituted the flood loops representing the stage-discharge relation and offered partial compensation for the scarcity of discharge measurements (bezdán 1994). besides backwater, dams are prone to raising also the groundwater table. owing to the local topography and soil conditions, this impact is especially pronounced in the surroundings of the novi bečej dam, where the groundwater never sinks below a certain elevation. higher groundwater under large areas in low-water periods has reduced the water absorbing capacity of the soil relative to the former, natural conditions. infiltration from the storage ponds built in the elevated parts of the catchment has also raised the groundwater table. the resultant impact consists of shorter low water periods and longer duration of mediumand high waters. the lowest water tables sustained by the dams are also higher than those prior to the construction of the storage ponds, which prevent the groundwater from sinking below a certain level even in dry periods. flood waves entering the hungarian reaches from the headwaters encounter drastically changed conditions, in that backwater raises base water levels in the rivers possibly without higher streamflow rates controlled by dams. conclusions any statistics of water levels, sediment transport and channel morphology compiled on the tisza river will be necessarily misleading without allowance for the fact that dams cause fundamental changes in hydrologic and sediment transport processes alike. this is why however long historical records and such created after the commissioning of dams must be considered separately. csongrád dam postponed repeatedly, would be an important link in the canalised tisza river. in a sequence of dams in which the backwater of a downstream one extends to the tailwater of the one upstream, silting in the headwater and erosion in the tailwater are much less pronounced than in more loosely spaced schemes. yet the river strives to attain equilibrium conditions so that high rates of sediment transport are attenuated gradually. according to experiences gained thus far, dams change the flow regime, raise the low-, mediumand high water levels, reduce flow velocity and cause silting. over the tisza reaches downstream of kisköre dam frequent and occasionally conspicuous natural and manmade backwaters (caused by the körös and maros tributaries, the novi bečej (törökbecse) dam and the danube) raise strong doubts as regards the effectiveness of emergency reservoirs upstream. higher levels of safety against floods of higher peaks and longer durations would be achieved by raising and strengthening appropriately the existing defences. acknowledgement the author is grateful to lászló márfai (ovk), tiborné göldner (ovk), miklós lázár (atikövizig), brandenburg róbert (atikövizig), lászló márfai (jun.) (atikövizig) and józsef szalai (vituki) for help in collection of data, and to levente jános for the ardous work of processing the data. i am also indebted to dr. jános rakonczai for advice and scientific support. references bezdán m. 1994. teljesítőképességi elemzés az algyői belvízrendszer példáján. hidrológiai közlöny 74/6: 381-383 bezdán m. 1997. a vízhozam és a vízállás különleges kapcsolatai a tisza vízjárásában. hidrológiai közlöny 77/3-4: 197202 bezdán m. 1998. kölcsönhatások a tisza-vízgyűjtő folyóin. hidrológiai közlöny 78/4: 247-249 bezdán m. 1999a. árhullámok előfordulása a középés alsótiszán. a magyar hidrológiai tárasaság vándorgyűlés kiadványa. miskolc: mht. 14-21 bezdán m. 1999b. a tisza balparti mellékfolyóinak hatása az árhullámokra. hidrológiai közlöny 79/2: 89-99 bezdán m. 2002. árhullámok befejeződése a középés alsótiszán. hidrológiai közlöny 82/2: 123-126 bezdán m. 2008. a folyó-vízszín természetes duzzasztásának és süllyesztésének hatásai a tisza középső és alsó szakaszán. hidrológiai közlöny 88/1: 9-26 bezdán m. 2010a. a vízszín-esések alakulása az alsó-tiszán. hidrológiai közlöny 90/5: 29-36 bezdán m. 2010b. a tisza szolnok és szeged közötti szakaszának vízszín-esése. hidrológiai tájékoztató 2010: 65-66 bogdánfy ö. 1906. a természetes vízfolyások hidraulikája. budapest: franklin társulat. 250 p bozán cs. – körösparti j. 2005. földárja a dél-alföldön. hidrológiai közlöny 85/3: 7-13 csatári b. et al. 2001. a tisza-vidék problémái és fejlesztési lehetőségei. fejlesztési program. kecskemét. online at: http://www.alfoldinfo.hu/tisza/tiszakotet.html giesecke j. – mosonyi e. 2005. wasserkraftanlagen. planung, bau und betrieb. berlin-heidelberg: springer verlag. 830 p dombrádi e. 2004. vízhozamés vízállásidősorok analízise a folyómeder állapotváltozásainak kimutatására. hidrológiai közlöny 84/4: 57-60 dunka s. – fejér l. – vágás i. 1996. a verítékes honfoglalás. a tisza szabályozás története. budapest: vízügyi múzeum, levéltár és könyvgyűjtemény. 215 p erdős f. 1920. tisza-szabályozás. a magyar mérnök és építész egylet közlönye 54: 5-11 gábris gy. − telbisz t. − nagy b. − bellardinelli e. 2002. a tiszai hullámtér feltöltődésének kérdése és az üledékképződés geomorfológiai alapjai. vízügyi közlemények 84/3: 305-322 huszár m. 1985. vízrajzi értekezés a körösvidékről (hungarian edition of the latin work, written in 1823). gyula: körösvidéki vízügyi igazgatóság. 63 p http://www.alfoldinfo.hu/tisza/tiszakotet.html 30 bezdán, m. joeg iii/1-4 iványi b. 1948. a tisza kisvízi szabályozása. vízügyi közlemények 30/2: 131-159, 30/3: 271-304 and 30/4: 398-435 koncz j. 1999. mit üzen ausztria keleti szomszédjainak a freudenaui dunai vízerőmű felavatása alkalmával? hidrológiai közlöny 79/3: 161-163 konecsny k. 2010. a kisvizek főbb hidrológiai statisztikai jellemzői a berettyó folyón. hidrológiai közlöny 90/4: 31-40 korbély j. 1909. az árvízjelzés, tekintettel a körösök és a berettyó vízjárására, valamint a tisza szegedi és csongrádi vízjárására. a magyar mérnök és építész egylet közlönye: 30-73 korbély j. 1937. a tisza szabályozása. debrecen: nemzeti könyvés lapkiadó vállalat. 25 p lászlóffy w. 1982. a tisza. budapest: akadémiai kiadó. 610 p marton l. 2010. alföldi rétegvizek potenciometrikus szintjeinek változása. hidrológiai közlöny 90/2: 17-21 nagy i. – schweitzer f. – alföldi l. 2001. a hullámtéri hordaléklerakódás (övzátony). vízügyi közlemények 83/4: 539-564 németh e. 1954. hidrológia és hidrometria. budapest: tankönyvkiadó. 662 p pálfai i. 2005. földárja, az alföld sajátos hidrológiai jelensége. hidrológiai közlöny 85/3: 15-18 pálfai i. 2011. aszályos évek az alföldön 1931–2010 között. in: rakonczai j. 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(ed.) a magyar vízszabályozás története. budapest. 281-370 völgyesi i. 2005. mennyit termelhetünk a felszín alatti vízkészletekből? hidrológiai közlöny 85/5: 20-24 völgyesi i. 2009. ökológiai vízigény, vagy megfelelő talajvízszintek. hidrológiai közlöny 89/5: 53-56 á assessment of ecological values of greening landscape elements journal of environmental geography journal of environmental geography 10 (3–4), 35–41. doi: 10.1515/jengeo-2017-0011 issn: 2060-467x assessment of ecological values of greening landscape elements in the great hungarian plain klaudia máté* department of landscape planning and regional development, szent istván university, 35–43 villányi str, h–1118 budapest, hungary *corresponding author, e-mail: mate.klaudia@phd.uni-szie.hu research article, received 20 october 2017, accepted 5 december 2017 abstract the research examines the effects of agricultural subsidies on the landscape structure. according to the hypothesis, greening – which has been introduced as part of the european union’s common agriculture policy (eu cap) reform –, if it is properly controlled and applied, can be a suitable tool for habitat network development. landscape elements eligible for greening can function as significant landscape structural elements, and can promote the achievement of goals e.g. in the preservation of biodiversity. as part of this research, field surveys were performed in 2016 and 2017 in the great hungarian plain, where significant landscape elements were assessed and documented in the sample area. during the research, shape index and fractal dimension index values for polygonal elements were calculated based on their current extensions in 2016 and in 2017. in line with my basic hypothesis, eligible landscape elements (such as hedgerows, stonewalls, shadoofs and infield trees) do not possess extraordinary ecological values, nor can their persistence be guaranteed solely with greening subsidies. therefore, they may also not be able to fill their role in the protection of landscape structure and biodiversity in the long term. keywords: greening, landscape element, efa, landscape structure, landscape indicator, shape index, fractal dimension index introduction according to the 2013 cap reform, eu member states are obliged to use 30 percent of their agricultural subsidies for environmental goals, collectively called as greening. in the greening starting in hungary in 2015, farmers have to fulfil criteria in three areas in order to receive subsidies: (1) maintaining permanent grasslands, (2) crop diversification and (3) designation of ecological focus areas (efas) (greening regulation, 2015). landscape planners could be especially involved in the designation of efas, as these can mostly be identical to landscape elements which are to be protected or have ecological values (allen et al. 2012). the main goal of the new agricultural subsidies is the protection of water and soil quality, and the preservation of biodiversity and rural agrarian landscapes (eu regulations 1307/2013 (44)). a long-term goal is the adaptation and mitigation of climate change. the experiences of the first year are worrying in terms of whether opportunities in landscape development provided by these subsidies can be exploited, and whether the measures serve the protection of truly valuable conservation areas (matthews, 2015; máté, 2017). this study attempts to answer a question if among greening landscape elements, those elements are really subsidised which are justifiably more stable ecologically. thus, it is examined whether the selection of eligible landscape elements is a result of consequent, professional decisions or they may have been selected without proper consideration, rather accidentally – which would constitute a long-term threat. the subsidies may have drawn the attention of not only the farmers but also landscape planners, ecologists, conservationist and other nature-related professionals, as they could effectively contribute to the improvement of landscape structure connectivity, to the increase of biotope network stability and even to halting the decrease of biodiversity (máté and kollányi, 2016). the delivery of obligations and undertakings of hungarian farmers is supported by the hungarian land parcel identification system (mepar). mepar is the exclusive, country-level system used in the subsidy processes (mepar regulation, 2015). on the online interface, every farmer and interested parties can search for their own parcel, of which they can learn further information thanks to the rich gis background database. at the end of 2015, the database has been extended with greening landscape elements, thus farmers can see which of them are efa eligible. according to the regulation, efas can be: fallow lands, terraces, landscape elements, buffer strips, eligible forest edges, agroforestry, short-rotation coppice, catch and cover crops, and nitrogen fixing crops (kovács et al., 2015). landscape elements can be the following habitats: field margins with trees, single trees, tree lines, tree and shrub groups, field margins, ponds, and ditches. the preservation of permanent grasslands and crop diversification are important for landscape structure mosaics. in addition, the conservation and creation of efas may bring significant changes in the ecological and biotope network. the protection of the ecological networks is especially important as nowadays, fragmentation – the breakup of natural habitats – is one of the most significant 36 máté (2017) threats to communities (didham, 2010). the role of landscape ecology is examining correlations in patterns, i.e. landscape structure, and various ecological processes (turner, 1989). human activities have a large impact on patterns which also has an effect on biodiversity (moser et al., 2002). during land use, natural mosaics and man-made patches form a fragmented landscape, where interconnection of natural habitats is not ensured in all cases (turner et al., 2001). bigger interconnected natural or semi-natural areas have become very rare by today. fragmentation negatively affects the survival of communities and does not only result in a shrinking habitat, it can also have negative consequences regarding biodiversity and species distribution (mairota et al., 2013). the widely known island biogeographical theory of macarthur and wilson (1967) can be applied with slight adjustments also to mainland habitat islands. according to the theory, larger islands have more species, and the larger the distances of the islands, the lower the number of species is. wilson and willis (1975) recognised that laws of island biogeography have important consequences for planning in protected areas. thus, it is preferable that the protected area be in a single block; have a rounded shape, i.e. a low perimeter-area ratio; and – if fragmented – have its fragments close to each other and have corridors between them. it is important however to mention a debate in conservation biolo gy still current today: the so-called sloss debate. it raises the question whether a fewer but larger, or more but smaller patches make the planning of protected areas more effective regarding biodiversity and connectivity. landscape indicators have proven to be very popular and efficient in the quantification of landscape patterns (gustafson, 1998). most landscape indicators are based on the perimeter-area ratio. one of the most basic patch-level indicator is the perimeter-area ratio (para) itself. most landscape ecology indicators examining patch shapes are based on this ratio. the most common criticism of the para indicator is that its value may change with the size of the patch. this error is fixed by the shape index (shape) indicator which compares the shape of a patch with a square of the same size, and which is widely used in landscape ecology researches (forman and godron, 1986). another patch level index based on the perimeter-area ratio is the fractal dimension index (frac). it is well known that the more compact shape a patch has, the more stable habitat it can provide for – as it is less affected by the so-called edge effect (helzer and jelinski, 1999). shape index has an interval of 1 to +∞, while fractal dimension index has an interval of 1 to 2 (szabó, 2009). both indices indicate a regular patch shape with 1, and higher values mark a higher irregularity. in this study, greening elements surveyed in a hungarian sample area are examined using the demonstrated landscape indices, in order to have a clearer picture on what ecological values do those greening landscape elements have which are supposed to meet the goals of biodiversity protection and landscape structure. study area the sample area is an about 120 km2 large on the dévaványa-ecseg fluvial plains, in the operational area of körös–maros national park, on the south-western edge of the former great sárrét region (fig. 1). an important characteristic of the area are the mosaics of saline plain remnants in the vicinity of the settlements ecsegfalva and dévaványa. these saline plains had been formed by secondary salinisation following the regulation of river tisza (from 1846). the floodplain grasslands, once rich in grass, had dried out, become salinated, and been placed under cultivation by local inhabitants (sallai, 1999). however, even the ploughing of grasslands had not caused the complete extinction of native species, thus certain species of the former plain grasslands have been preserved in the secondary saline communities and weed communities with wild flowers peculiar to the transtisza region (dövényi, 2010). some parts of the sample area are under various nature protections – there are local protected areas, highly protected areas, natura 2000 and national ecological network core areas, buffer zones and corridors; also, the entire sample area is part of the “dévaványa and surroundings high natural value area”. fig. 1 location of the sample area and assessed elements the region belongs to the significant agricultural areas of hungary. the islands of protected areas are surrounded by intensively cultivated arable lands. in the designation of the sample area, both natural and artificial landscape boundaries were taken into account. thus, the sample area is bordered by the unregulated river bends of hortobágy-berettyó to the west, road 4205 connecting ecsegfalva and dévaványa to the north and to the east, and dirt roads with larger agricultural traffic to the south. methods preparations for the field survey were made using qgis 2.10.1 pisa (qgis, 2010). efa eligible elements were displayed using mepar symbols. the path of the field assessment of ecological values of greening landscape elements … 37 survey was planned in a way that it passes by all efa elements in the sample area. the first field survey was performed between 12 july and 13 august 2016, and the second one between 8 and 10 september 2017. both efa elements and other non-efa elements – in total, 48 point, linear and polygonal elements – were assessed. among the data assessed on the spot were: efa type verification, general ecological and condition attributes, species composition, gps coordinates for later display on map, and photo documentation of all elements. as part of processing the field work, a gis database was built which contained all the assessed elements. the shapes of the assessed patches were drawn based on their shapes in mepar in case of efa landscape elements, and as a result of merging field surve y data with cartographic post-production in case of nonefa elements. the shape index and the fractal dimension index of these shapes was then calculated in arcgis 10, using the v-late extension. in the gis database, shape index and fractal dimension index values and photo id numbers were registered, along with year, the fact of efa eligibility, ecological condition and species composition, and in some cases an additional note (e.g. terminated efa eligibility or disappeared element) (table 1). the structure of the database allows for incorporating results of studies in the following years as well, and for comparison of the results. in this study, only the shape index (shape) and fractal dimension index (frac) of patch-like efa and non-efa landscape elements were examined, as their values can be calculated only for this type of elements. 22 landscape elements were examined, which can be divided into two categories: tree and shrub groups, and ponds. first eligible and non-eligible elements were examined using student’s t-test, but as the conditions of normality and homogeneity of variance were not fully met, a simpler yet more reliable analysis was needed. after individually calculating both indices of each 22 patch-like elements, the averages of the values were calculated in each group for each year, differentiating efa and non-efa elements. for a preliminary overview, understanding and sanitisation of data, they have been displayed as bar graphs in microsoft excel software. during the field surveys, pictures were taken of every element, which can be used not only for documenting year to-year changes but also for visually comparing “protected” and “not protected” landscape elements. the collation of the photo documentation was an especially important step of the annual field survey, as it could also be regarded as an annual monitoring of landscape elements in the sample area. the photo documentation was performed for all surveyed elements both in 2016 and 2017. as for linear landscape elements, there was no basis for comparison, as tree lines defined in the greening starting in 2015 were still not visible in mepar in summer 2016. it should also be noted that the efa designation of tree lines are professionally objectionable. as table 1 surveyed polygonal elements and their attributes nr landscape element type dominant species eov coordinates of centroids 2016 2017 x y efa shape frac efa shape frac 001 tree and shrub group robinia sp. 193585.88 780233.37 1.24 1.37 1.24 1.37 002 tree and shrub group robinia sp. 192963.25 780231.38 x 1.39 1.44 x 1.20 1.43 003 tree and shrub group robinia sp. 192453.76 780685.41 x 2.09 1.53 x 2.09 1.53 004 tree and shrub group robinia sp., fraxinus sp. 192368.25 780867.80 x 1.68 1.47 x 1.37 1.43 006 tree and shrub group robinia sp. 193359.50 781262.40 5.61 1.64 5.61 1.64 014 tree and shrub group robinia sp. 197110.67 787860.39 1.12 1.30 1.12 1.30 016 tree and shrub group robinia sp., populus sp. 196268.89 789875.49 1.15 1.50 1.15 1.50 019 pond phragmites sp. 196140.55 790019.94 1.35 1.38 1.35 1.38 020 tree and shrub group populus sp. 195972.77 790024.31 2.39 1.59 2.39 1.59 021 tree and shrub group populus sp. 195884.43 790061.47 1.20 1.49 1.20 1.49 024 tree and shrub group robinia sp., salix sp. 194492.93 790048.27 x 1.25 1.50 x 1.25 1.50 025 tree and shrub group robinia sp. 195334.15 788756.92 1.25 1.36 1.25 1.36 031 tree and shrub group robinia sp., salix sp. 198939.82 792832.33 x 1.58 1.42 1.58 1.42 033 tree and shrub group robinia sp., salix sp., quercus sp., fraxinus sp. 197989.55 792549.66 2.25 1.42 2.25 1.42 034 tree and shrub group fraxinus sp. 197051.64 792482.59 x 1.81 1.48 x 1.79 1.48 035 tree and shrub group robinia sp. 192918.89 792775.08 x 1.41 1.38 1.41 1.38 036 tree and shrub group robinia sp., salix sp. 192588.15 793034.73 x 1.27 1.37 x 1.27 1.37 038 tree and shrub group salix sp., robinia sp. 192368.43 791992.98 3.60 1.67 3.60 1.67 039 tree and shrub group robinia sp. 192342.62 790979.08 1.42 1.53 1.42 1.53 040 pond carex sp. 192213.82 790846.07 x 1.19 1.35 x 1.19 1.35 044 tree and shrub group robinia sp. 193130.75 785019.50 3.10 1.58 3.10 1.58 047 pond salix sp., phragmites sp. 193684.56 783867.91 1.16 1.37 1.16 1.37 38 máté (2017) of 2017, the mepar layer for tree lines is available. unfortunately however, on the 120 km2 sample area there is not a single official efa tree line. results shape index and fractal dimension index values of the assessed elements the averages of shape values for each eligible and noneligible efa types in 2016 and 2017 can be seen on figure 2. it can be stated that in general, efa-eligible patchlike landscape elements have lower shape values in the sample area in both years, thus they can be regarded as ecologically somewhat more stable than non-eligible elements. the figure shows that eligible landscape elements in 2016 have a higher shape (1.52) value, thus are ecologically somewhat less stable than eligible elements assessed in 2017 (1.45). fig. 2 average shape values of the assessed elements in 2016 and in 2017 no significant change can be demonstrated in frac values in the assessed efa landscape elements from 2016 to 2017 (fig. 3), and the change in frac values of non-efa elements is also negligible from 2016 to 2017 (0.01). fig. 3 average frac values of the assessed elements in 2016 and in 2017 there is a similar tendency in the 2016 and 2017 shape values of the assessed tree and shrub groups in the sample area to the overall values (fig. 4). in 2016, the shape index value of efa tree and shrub groups was 1.56, which decreased to 1.49 in 2017. this means that based on their shape value, these groups are more stable. a similar change can be observed for nonefa elements. in 2016, the shape value was 2.21, while in 2017 it decreased to 2.10. as for ponds, there is no change over the two years. fig. 4 changes in the shape index of the assessed tree and shrub groups in 2016 and in 2017 differences in the assessed elements although we could get a relatively relieving result when examining the shape index and fractal dimension index of the assessed elements, as efa elements have lower values, yet concerns for valuable landscape elements are not unfounded. the following examples demonstrate that for elements of each dimensional type (point, linear and polygonal), valuable elements have not been selected in all cases as efa elements. in the case of point landscape elements, the main groups are shadoofs, tumuli and individual trees. the comparison of the following two individual trees is an instructive example. the populus in figure 5a (2016) and 5b (2017) is not listed as an efa element, despite meeting all prerequisites. the tree in figure 5c (2016) and 5d (2017) is an individual tree efa element in mepar even though it barely fulfils the preconditions. fig. 5 non-efa individual tree (a and b) and efa individual tree (c and d) in 2016 and 2017 (k. máté) assessment of ecological values of greening landscape elements … 39 tree lines in figure 6a and 6b are officially not regarded as efa elements, despite their very significant role in the landscape structure both as a habitat and as a protection for arable lands. they can be defined as significant landscape character elements in the intensively cultivated agricultural landscape. among polygonal elements, the greatest contrast was discovered regarding ponds. in figure 7a (2016), the pond (a former borrow pit) fulfils all criteria, has clean water, is surrounded by arable land s but also by a lakeside margin. its ecological value is outstanding in its area, a high diversity of species was observed during the field surveys, it is a favourable bird resting place. still, it is not efa eligible. however, the former borrow pit which dried up and became filled with soil (fig. 7b (2016)) is eligible. the difference between the two landscape elements is obvious, the difference in their efa eligibility is harder to grasp. no change was found in these two ponds during the 2017 field survey. the pond with a large open water surface is still not efa eligible, while the efa eligible pond still has low ecological value. the only change regarding the latter is that dry trees standing on the side of the lake bed have been removed by 2017. fig. 7 non-efa eligible (a) and efa eligible (b) ponds in 2016 (k. máté) changes in eligibility and conditions during the 2017 survey, on numerous occasions, the decrease or complete cessation of the eligible area of a landscape element was observed. the field margin in figure 8a (2016) and 8b (2017) was placed in the category of permanent, not sensitive grasslands in 2016. as for its species composition, it was mostly composed by agricultural weed species. by the 2017 field survey, the grassland field margin could not be found any more: it has been cultivated together with the field and was sowed with sunflowers. fig. 8 a disappeared permanent, not sensitive grassland field margin in 2016 (a) and in 2017 (b) (k. máté) discussion based on the results it can be stated that the concerns of experts regarding appropriate designation of greening elements is well-founded. no significant difference can be demonstrated between shape and frac values of efa-eligible and non-eligible elements, the year-to-year changes however show a rising trend in the ecological stability of patches. it has to be added though that no farreaching conclusions can be drawn from a two -year set of data. the minimal change in shape and frac values can be explained by the fact that two surveyed tree and shrub groups were efa-eligible in 2016 but were fig. 6 officially non-eligible tree lines in 2016 and 2017 (k. máté) 40 máté (2017) removed from the mepar layer for eligible elements in 2017 – thus, there was a difference in the number of elements in the efa and non-efa groups. still, the experiences of the field survey imply that there are certain eligible elements which are ecologically insignificant, and there are “not protected” elements which represent significant ecological value and can contribute to the structural stability of the landscape. the shrinking of eligible areas on mepar layers did not appear in the landscape in the range of one year, no significant felling took place from one year to the other in tree and shrub groups or in tree lines. these hidden pitfalls however may have their e ffect on the landscape structure elements in the long term. the area shrinking of officially eligible tree group patches in mepar may be followed by an actual shrinking in reality. the slow but gradual expansion of fields at the expense of dirt roads or grassland field margins is a commonplace issue, as it was shown. similar problems can be expected regarding tree and shrub groups – the unified area-based subsidisation and the hectare-based support of greening may both be incentives for farmers to keep only those patches for which they can receive subsidies. ecological values play no significant role in these cases. the decrease of shape values of the efa elements from 2016 to 2017 can be seen in figure 2. the 0.07 decrease does not allow for far-reaching conclusions, also because of the low number of elements; however, there are real changes in areas and shapes behind this figure which bring a demonstrable result based on the methodology. the changes of shape values of tree and shrub groups seen in figure 4 can be traced back to similar reasons. of the surveyed elements, two efa tree and shrub group elements have disappeared by 2017 (number 031 and 035), thus farmers could not receive subsidies for their preservation this year. the shape and frac values of elements 002 and 004 have decreased, while in case of element 034 only the shape value has changed. the decrease of the overall value shows a positive change in the patch shapes regarding ecological aspects. in figures 2, 3 and 4, a small change can be demonstrated for non-efa elements. the reason behind this may be the reclassification of two formerly efa tree and shrub groups to the non-efa group in 2017. as for the shape and frac values of individual non-efa elements, no change can be demonstrated based on table 1. this stagnation is due to the fact that unlike annually updated mepar layers for efa elements, there is no annually updated patch designation for non-efa elements. therefore, an annual change for non-efa elements can be demonstrated only in case a significant change in area can be perceived during the field surveys which can be represented in a gis system. comparing the areas of efa and non-efa elements is thus recommended only with great caution. as table 1 shows, robinia pseudoacacia is the dominant species in a major part of tree and shrub groups in the sample area. the composition of vegetation is a key in defining the ecological values. unfortunately, the occurance of native woody plants is scattered, and they can be mostly found in the highly protected national park areas. thus, greening landscape elements marked as protected and ecologically significant are in most cases actually patches consisting of the invasive robinia pseudoacacia. conclusions in the study, the shapes of 22 patch-like greening landscape elements and the landscape metrics analysis of their changes over two years is shown. based on landscape indices, patches have become more compact from 2016 to 2017 according to both the shape index and the fractal dimension index. however, the positive trend displayed by these patch indices are overshadowed by the findings of the field survey, namely that the dominant species of all patch-like element was the robinia pseudoacacia. the experiences of the research amplify concerned voices regarding the success of greening. it is important to emphasize that financial incentives do not lead farmers towards the goals that had been originally defined. the fundamental goal of greening is the protection of biodiversity – however, the inappropriate efa designation renders its achievement impossible, if tree groups consisting of invasive species and dried-up lake beds are also eligible for support and protection. it is necessary to raise the awareness of farmers to the ecological values of elements like tree lines consisting of native species, tree groups hiding nests of birds of prey or lakes with permanent water surface. acknowledgements i would hereby like to thank dr márta ladányi associate professor for her help in performing statistical analyses, and the two anonymous reviewers for their exceptionally useful remarks. supported by the únkp-17-3 new national excellence program of the ministry of human capacities. references allen, b., buckwell, a., baldock, d., menadue, h. 2012. maximising environmental benefits through ecological focus areas. lupg uk. didham, r. k. 2010. ecological consequences of habitat fragmentation. encyclopedia of life sciences published online: 15 nov 2010 dövényi, z. 2010. inventory of microregions in hungary, hungarian academy of sciences, geographical institute, budapest. (in hungarian) european parliament and council, resolution no. 1307 of 2013 (xii. 17.) about establishing rules for direct payments to farmers under support schemes within the framework of the common agricultural policy and repealing council regulation (ec) no 637/2008 and council regulation (ec) no 73/2009 forman, r. t. t., godron, m. 1986. landscape ecology. wiley. gustafson, e. j. 1998. quantifying landscape spatial pattern: what is the state of the art? ecosystems 1, 143–156. doi: 10.1007/s100219900011 helzer, c. j., jelinski, d. e. 1999. the relative importance of patch area and perimeter–area ratio to grassland breeding birds. ecological applications 9(4), 1448–1458. doi: 10.2307/2641409 assessment of ecological values of greening landscape elements … 41 kovács, m., kránitz, l., madarász, i., magyari, r., palakovics, sz., pethő, j., rezneki, r., szabó, e., szerletics, á., sztahura, e., tengerdi, g., zemle, v. 2015. greening handbook for farmers. nemzeti agrárgazdasági kamara, budapest. (in hungarian) macarthur, r. h., wilson, e. o. 1967. the theory of island biogeography. princeton university press máté, k. 2017. examination of greening landscape elements. in: blanka, v., ladányi, zs. (eds): interdiszciplináris tájkutatás a xxi. században: a vii. magyar tájökológiai konferencia tanulmánykötete, 417–424. máté, k., kollányi, l. 2016. the potential impact of greening as a directed land use on the landscape structure. in valánszki, i., jombach, s., filep-kovács, k., fábos, j. gy., ryan, r. l., lindhult, m. s., kollányi, l. (eds), greenways and landscapes in change – proceedings of 5th fábos conference on landscape and greenway planning. budapest, 30 june, 2016, 79–87. mairota, p., cafarelli, b., boccaccio, l., leronni, v., labadessa, r., kosmidou, v., nagendra, h. 2013. using landscape structure to develop quantitative baselines for protected area monitoring. ecological indicators 33, 82–95. doi: 10.1016/j.ecolind.2012.08.017 matthews, a. 2015. delivering biodiversity through the common agricultural policy. in: ó huallacháin, d. finn, j.a. (eds.) farmland conservation with 2020 vision, teagasc, wexford, 10–11. ministry of agriculture of hungary, resolution no. 10 of 2015 (iii. 13.) about greening (greening regulation) (in hungarian) ministry of agriculture of hungary, resolution no. 71 of 2015 (xi. 3.) about the hungarian land parcel identification system (mepar) (mepar regulation) (in hungarian) moser, d., zechmeister, h.g., plutzar, c., sauberer, n., wrbka, t., grabherr, g., 2002. landscape patch shape complexity as an effective measure for plant species richness in rural landscapes. landscape ecol. 17, 657–669. doi: 10.1023/a:1021513729205 quantum gis development team (2010). quantum gis geographic information system. open source geospatial foundation project. http://qgis.osgeo.org sallai, r. b. 1999. field trips around túrkeve, herman ottó természetvédő kör, túrkeve. p.7. szabó, sz. 2009. examining potential applications of landscape metrics in landscape analysis. habilitation dissertation. university of debrecen, faculty of science and technology, department of landscape protection and environmental geography. debrecen. turner, m. g., gardner, r. h., o’neill, r. v. 2001. landscape ecology in theory and practice: pattern and process. springer-verlag, new york. turner, m.g., 1989. landscape ecology: the effect of pattern on process. ann. rev. ecol. syst. 20, 171–197. doi: 10.1146/annurev.es.20.110189.001131 wilson, e. o., willis, e. o. 1975. applied biogeography. in m. l. cody and j. m. diamond (eds.) ecology and evolution of communities. harvard university press, cambridge, massachusetts, usa, 522−534 introduction study area methods results shape index and fractal dimension index values of the assessed elements differences in the assessed elements changes in eligibility and conditions discussion conclusions acknowledgements references journal of environmental geography journal of environmental geography 7 (1–2),1–9. doi: 10.2478/jengeo-2014-0001 issn: 2060-467x 18 th -century daily measurements and weather observations in the se-carpathian basin: a preliminary analysis of the timişoara series (1780-1803) ildikó csernus-molnár 1 , andrea kiss 2 , edit pócsik 3 1 department of history, central european university, nádor u. 9, h-1051 budapest, hungary 2 institute of hydraulic engineering and water resources management, vienna university of technology, karsplatz 13, 1040 vienna, austria 3 institute of communication in foreign languages, university of szeged, honvéd tér 6, h-6722 szeged, hungary *corresponding author, e-mail:kiss@hydro.tuwien.ac.at research article, received 26 january 2014, accepted 15 march 2014 abstract covering a period of 23 years, the timişoara (in historical banat region; today sw-romania) series is the earliest known long-term 18 th -century daily measurement (temperature, pressure) and weather observation series (precipitation, sky coverage, meteorological extremes), preserved in the south-eastern lowlands of the carpathian basin. based on data derived from the original weather diary of the royal pharmacist karl joseph klapka, in this paper the early instrumental measurement and daily observation series is presented referring to th e temperature, pressure, precipitation conditions, cloudiness, wind, types of precipitation and extreme weather events that occurred in timişoara in the period of 1780 -1803. the two daily temperature measurement series show very high (over r=0.95) correlations, while pressure series are also in good agreement with other known late 18 th -century measurement series of the same period in the carpathian basin (buda, miskolc and kežmarok). the timişoara-series also contains important information concerning such w eather extremes as the severe winter of 1784 or the unusual number of summer fog events in 1783 (presumably related to the icelandic lakagígar eruption), which are also r eported in the present paper. keywords: historical climatology, early instrumental measurements, daily weather observations extreme weather events, 18 th century early instrumental measurements and meteorological observations in historical hungary the 18 th century is of basic importance from the viewpoints of the implementation of a uniform european measurement network and also from the development of meteorology and climatology in historical hungary that covered the majority of the carpathian basin. the instrumental measurements and daily visual weather observations, carried out at the end of the 18th century, already provide much more accurate information on the weather conditions of the period – mainly on the temperature, pressure and precipitation events – than the earlier ones (e.g. szőkefalvi-nagy and zétényi, 1965; réthly, 1970). both inside and outside of the societas meteorologica palatina network, these records were usually made by (highly) educated people; in most cases by physicians, pharmacists, astronomers or members of the clergy (brázdil et al., 2002, 2005; demarée et al., 2002). measurements and observations were initiated mainly on the basis of uniform methods, and thus, clear similarities in practices can be traced, for instance, in the spanish, swedish, belgian, italian and czech analyses. these previous investigations can help in the methodology to process manuscripts, and correct as well as analyze data gained from the manuscripts (barriendos et al., 2002; brázdil et al., 2002, 2003; camuffo, 2002a etc.). mainly due to the assembling work of antal réthly (1970), there are four known instrumental mea surement series, combined with daily weather records, extending over several years from this time -period in the area of historical hungary (fig. 1). firstly, the series of buda station (buda observatory) should be mentioned, which operated as a member of the societas meteorologica palatina european measurement network, and its measurements were systematically documented in the societas yearbooks until 1792. the temperature data and the daily visual observations from miskolc (hungary) between 1780 and 1801 (t ogether with pressure series in 1780 and in the period 1794 1800), appeared in published form in 1794 and 1802 (by benkö, 1794, 1802), and were partly analyzed (see szőkefalvi-nagy and zétényi, 1965). additionally, observations and measurements carried out in kežmarok (in slovakia; historical késmárk) between 1789 and 1800 by jános genersich, remained in hand written form (national széchényi library, budapest, fol. germ. 114), similar to the data of timişoara (in romania; temesvár in historical hungary). 2 csernus-molnár et al. (2014) recently, a complex processing of the miskolc and kežmarok originals has been carried out. these additional data can help us to provide an even more detailed picture of the weather patterns characterizing the carpathian basin in the late 18 th century. this paper presents the measurements and daily records carried out in timişoara: the digitalization of klapka’s written records – extending over 23 years – made it possible for us to perform the statistical analyses of the temperature and pressure data, as well as that of the daily meteorological observations. the importance of this work arises from the fact that, except for one publication concerning the miskolc temperature series (szőkefalvi-nagy and zétényi, 1965), the in-depth, detailed analysis of the hungarian instrumental measurements and daily observations from the late 18 th century, apart from the buda(pest) series (the only late 18 th century series included in the societas meteorologica palatina network), have not been provided in published form. the klapka-manuscript and data processing the original manuscript can be found in its entirety in the manuscript and rare book collection of the eö tvös loránd university library in budapest (catalogue no. e 40). the observer, karl joseph klapka, was a royal pharmacist, coming from znojmo (southmoravia), who moved to timişoara around the year 1780 (szinnyei, 1900; klapka, 1886). although no information is currently available on the exact loc ation of his measurements in timişoara, it is quite probable that the measurements took place at the building (yard?) of the pharmacy located in the city centre. except for one or two missing days, an esse ntially continuous data series is available concerning the years between 1780 and 1803. the diary consists of data measured three times every day. the temper ature measurements were carried out simultaneously by two thermometers (in réaumur and fahrenheit). in case of pressure measurements, the scale was divided according to the paris measure in inches (‘grad’) with values of 26, 27 and 28, every inch with 12 line s (‘dig’) and every line with 10 units. in addition, klapka regularly (three times a day) added info rmation about the state of sky, cloudiness, wind variety and precipitation events (with types mentioned). as the first step of digitalization, the numerical and textual information, available in the klapka ma nuscript, was converted (i.e. typed in) to an excel file: in case of pressure the inch values had to be comple ted, while negative temperature values (with the sign "under zero") were converted to negative values. due to the very uniform use of ink and the homogeneity of handwriting, we presume that the available manuscript was the copied, finalized version of the mea surements. in a few cases, when a copying mistake of values was obvious (e.g. missing sign of negative value), we have corrected the actual number. co ncerning the description of daily weather conditions, the precipitation-related narrative information was interpreted and transformed into numerica l values (see details later). after digitalization and interpretation of the manuscript, the temperature and pressure series, and the daily records (written in latin) were suitable for statistical analysis. one of the great advantages of the klapkamanuscript is that it provides continuous information for the period between 1780 and 1803, thus a data series characterized by unique continuity is available for this region, and for the south-eastern region of the carpathian basin in particular. it is an essentially important fact, since regular daily reports of the societas meteorologica palatina were put aside for a few years after 1792. as a consequence, the daily fig. 1 location of places mentioned in the paper (thick black line: 18 th century borderlines of countries that belonged to the hungarian crown; thin black line: present day country borders) 18 th -century daily measurements and weather observations in the se-carpathian basin … 3 observations carried out at the end of the century in buda are not available; only monthly aver ages are known. the other advantage of this measurement series is that it originates from the last decades of the 18th century thus coincides with the so -called ‘maldá-anomaly’, a period famous for its extreme weather conditions (barriendos et al., 2003; b rázdil et al., 2003). temperature measurements the early liquid-in-gas thermometers were very different from each other in many respects, namely d eformation of the glass tube and bulb, polymerization of organic thermometer liquids, slipping of the scale or the capillary etc. which can cause measuring errors (camuffo, 2002b). in this way, in order to be able to carry out statistical analysis of the data the two types of temperature measurement series provided by klapka, had to be converted into one common unit of measure – in our case the celsius degree scale. furthermore, the comparison of the data recorded in the manuscript with the contemporary measurements of buda, kežmarok and miskolc allows us to carry out a comprehensive analysis. in case of the timişoara series, using the celsius values derived from the measurements in fahrenheit and réaumur, morning, noon, evening and daily averages could be calculated. for the calculation of daily averages the kämtz method was applied: (1* morning+1* noon+2* eve ning)/4 (see e.g. dall’amico and hornsteiner, 2006; see also kern, 2009). the values measured by two different types of thermometers were practically identical to each other (r=1), correlated well both with the contemporary monthly temperature data series of buda (r=0.98) (fig. 2) and with the temperature data series of the period 1961-1990 measured in timişoara (r=0.99) as well. moreover, monthly values show strong correlation with the available contemporary measurement series of miskolc (r=0.94) and kežmarok (r=0.97). the second figure (fig. 2) shows the monthly averages of temperature values in timişoara and in buda regarding the studied 23 years (1780-1803). it is conspicuous that, after 1783, there is a difference of a pproximately 3 degrees on average between the two observation sites: the monthly temperature values in timişoara are all-time higher than those of buda (which fits the general differences in climate ), which is particularly visible in case of mild winters such as 1786, 1792, 1796, 1798 or 1800. it has to be emph asized, however, that difference between the buda and timişoara temperature series is much less significant in case of summer, and even less detectable in case of autumn and spring values (see fig. 2). moreover, the daily course of mean temperatures referring to the entire study period, in general, reflects values comp arable to the 20th-century differences in climate (fig. 3). nevertheless, the generally high winter values and relatively small differences in the course of daily temperature might allow the possibility of some infl uence of heating (it was a common practice /especially in towns/ to put the thermometers on the wall, or place them in courtyards etc.). fig. 2 monthly averages of temperature values measured in timişoara and buda in 1780-1803 (ºc) 4 csernus-molnár et al. (2014) fig.3 daily course of temperature measured in 1780 -1803, in timişoara (ºc) the values transformed are still raw data series, and it follows from that, that a deeper and more accurate analysis should be carried out in future. comparing the annual courses of temperature series in 1780-1803 and 1961-1990 (fig. 4), it comes clear that monthly temperatures measured in 1780-1803 are generally 2-3 ºc higher than those measured in 1961-1990 in timişoara; this difference can reach 5 ºc in winter months. thus, higher degrees can be systematically detected not only compared to the contemporary buda measurements (located ca. 250 km northwest to timişoara with the great hungarian plain in between), but also to the present-day (1961-1990) timişoara data series. what could be the reason of this difference, especially in winter time? the clear reasons are unknown; nevertheless, the urban location of the pharmacy, and the contemporary practices of settling the instruments (maybe an inner yard location, thermometer placed on the wall) or some technical reasons (installation) can also be responsible for the differences. since positive temperature anomalies can primarily be detected during mild winters and they are less visible during summers, the effect of insolation seems to be a less likely reason for the higher temperature values. based on the klapka-measurements, in timişoara especially the summers of 1781, 1788, 1794 and 1802 turned out to be outstanding warm. the extraordinary hot summer of 1783, which was reported in large parts of central europe (brázdil et al., 2003), was not an unusually hot summer in timişoara concerning monthly averages (see fig. 2). on the basis of monthly average temperatures, the hardest winters in timişoara occurred in 1782, 1789, 1795 and 1799, which were otherwise accompanied by ice jam floods along the danube in the carpathian basin, similarly to some other areas in central europe (see e.g. strömmer, 2003; kiss, 2007; glaser, 2008; brázdil et al., 2010). due to its severe conditions and the great and extraordinary winterand spring-flood events, the winter of 1784 (after the great lakagígar eruption in iceland) is considered as one of the most famous european extremes in the last decades of the 18th century (for a european overview of flood waves, background and consequences, see brázdil et al., 2008). although the winter of 1784 was clearly col der than usual in timişoara, if we merely take the temperature averages into consideration, it was not one of the coldest winters of the study period. it is rather due to the great temperature variations (very cold periods were interrupted by rather mild ones), reflected in the course of daily temperatures as well as the values of daily maximum and minimum te mperatures (fig. 5), that this winter was reported as a notably cold one in the carpathian basin, when both ice jam flood (e.g. in december on the maros river) as well as floods due to snow-melt (from january) occurred around timişoara and in the banat area (see e.g. kiss et al., 2006; kiss and csernus-molnár, 2008; kiss et al., 2008). fig.4 annual course of measured temperature values in timişoara: 1780 -1803, 1961-1990 (in ºc) 18 th -century daily measurements and weather observations in the se-carpathian basin … 5 the late 18th century was also rather rich in individual temperature extremes in central europe, and also in timişoara and the carpathian basin. in timişoara, the coldest december occurred in 1788 ( 2.6 ºc measured by klapka; in 1961-1990: 0.8 ºc), the coldest march (0.3 ºc; 1961-1990: 5.8 ºc) and spring were measured in 1785 (1.7 ºc; 1961-1990: 11.1 ºc), whereas the warmest april occurred in 1800 (19.2 ºc; 1961-1990: 11.2 ºc). air pressure measurements similar to temperature, pressure measurements were provided three times per day in a rather systematic way. even if klapka provided no evidence on the measurement unit of his pressure data series, based on the values included in the manuscript, the pressure data presumably were recorded in paris inches, which was widely applied in this period in europe. from the original daily values, transformed to hpa form, daily and monthly averages were calculated (fig. 6): although the annual pressure averages show some parallels to those measured in timişoara between 1961 and 1990, the non-corrected values are significantly lower than the ones measured in the 20 th century. apart from the fact that these are still raw values (not corrected to temperature or reduced to sea elevation), the values will change after corrections, the problem of low values clearly needs further elaboration. similarly to the analysis of the temperature data, for further quality assessment of the pressure measurements carried out in timişoara, the daily data series of buda were applied, the raw data of which were obtained from the mannheim series of the societas meteorologica palatina (ephemerides… 1781-1792), and transformed to hpa using the aforementioned formula. as, similarly to the fig. 5 daily measured temperature (provided in ºc; thermometers: f=fahrenheit; r=réaumur): average (green lines), maximum (red) and minimum (blue) values in timişoara between 1 dec. 1783 and 31 march 1784 fig. 6 comparison of monthly averages of pressure values (without corrections), measured in the periods 1780-1803 and 1961-1990 in timişoara -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 1 5 1 0 1 5 2 0 2 5 3 0 1 5 1 0 1 5 2 0 2 5 3 0 1 5 1 0 1 5 2 0 2 5 1 5 1 0 1 5 2 0 2 5 3 0 december january february march f r min. f min. r max. f max. r ˚c 6 csernus-molnár et al. (2014) temperature series, the pressure series from buda also contains values measured three times every day, it could be compared with the pressure values measured in timişoara. the correlation between these monthly averages is also strong (r=0.58; <0.01 significance level): the strongest correlation can be detected in winters (e.g. in january of 1784: r=0.98), while the lowest were in summers (e.g. in july of 1783: r=0.37). the daily values are also comparable with measurements of miskolc (r=0.24; 0.01 significance level) and kežmarok (r=0.87; <0.01 significance level; with rel. short overlapping period). low correlations with the miskolc pressure measurement series can also be caused by the fact that the miskolc series are rather problematic as (when provided) only one value is available for each day without any information on the time of measurement (see also szőkefalvi-nagy and zétényi, 1965). comparing the timişoara (raw) pressure series (1780-1803) to the measured (corrected) values of 1961-1990, similarly strong connection can be detected (r=0.65; <0.01 significance level). this fact also highlights the considerable potentials of this early and almost uninterruptedly recorded 23-year long series. daily observations, with special emphasis on precipitation patterns beyond recording the measured temperature and pressure values, klapka also provided a systematic description of weather events (e.g. precipitation, atmospheric phenomena) three times every day in latin. since the application of contemporary terminology, the use of specific words have special importance in proper understanding of weather conditions, it is necessary to provide the precise, present-day interpretation of the more important terms. terms appearing most often in the manuscript refer to transparency, cloudiness, type of precipitation (e.g. snow, fog), motion of air (e.g. windy) or to temperature (e.g. cold, hot). however, some individual phenomena (e.g. rainbow) also appear in the manuscript (see table 1). in addition to the measured temperature and pressure values, the aforementioned observations provide us more information for instance about the number of days with precipitation, the physical condition of precipitation, the number of cloudy or of foggy days. from all these information the systematically recorded daily evidence on precipitation might be the most important. precipitation observations a significant further section of the daily observation records refers to precipitation. although no precipit ation measurements were carried out, klapka recorded the information on precipitation every day. from this evidence, it is possible to calculate days with precip itation, dividing the information according to precip itation types. after aggregating the number of days with precipitation summed up for each month, the numbers of rainy, snowy and mixed days were sep arately grouped (fig. 7). at the same time the manuscript also provides some information on trace precipitation (mostly about the number of foggy days see later), which were treated separately from normal precipitation information. we have to note that even if some comparisons were carried out with precipitation measurement data series, the number of days with precipitation is not equivalent to the amount of precipitation measured in other places. moreover, it is po ssible that precipitation events during the night were sometimes not recorded in the manuscript. precipitation results (quantity) were compared with the daily precipitation data of buda, published in the volumes of the societas meteorologica palatina (ephemerides… 1781-1803). the correlation between the buda and timişoara datasets shows connection on 5% significance level (r=0.27). thus, despite the great distance (over 250 km) and the differences in precip itation patterns, some connections could be detected with the contemporary measured precipitation datasets of buda, which supports the further potentials of the late 18 th -century daily precipitation information recorded in timişoara. at the same time, the manuscript also reflects on some of the dry (such as 1794, 1797, 1800, 1802 etc.) and rainy years (such as 1786, 1795, 1801). in the latter case, table 1 basic terminology applied in the descriptions of daily visual observations latin term english meaning latin term english meaning 1. sky coverage, transparency 3. motion of air ventus, ventosus wind, windy nubilum, nubiles cloudy, clouds (semi-) serenum (sereno) (half-) clear sky (air) obscurum unclear, grey/dark weather (sky) 4. temperature-related terms 2. types of precipitation, physical condition frigidus, frigeo (frigefacto) cold, cooling down pluvia (pluvius, pluviosus) rain (rainy) calidus (caleo) warm nives, ningo/ninxi, (nivosus) snow, snowing (snowy) 5. atmospheric phenomenon nebula fog arcus pluvius rainbow 18 th -century daily measurements and weather observations in the se-carpathian basin … 7 the number of days with more significant precipitation events exceeds 100 (e.g. 1786, 1792, 1795; see fig. 7). concerning anomalous and extreme months, the springs of 1794, 1801 and 1802, the summers of 1784, 1788, 1793, 1800, 1802 and 1803, the autumns of 1783, 1793, 1797 and 1802, the winters of 1790, 1794, 1796 and 1801 appeared to be particularly dry. nevertheless, the summer of 1801, the autumns of 1791, 1794 and 1801, the winters of 1781, 1792 and 1795 seem to be particularly rainy. on an annual scale 1790, 1793, 1802 (where not only the spring but also the autumn) and 1803 were dry at least based on the number of days with precipitation. as we pointed out earlier, it is an important fact that the number of days with precipitation events is not always closely related to the amount of precipitation: that is why, for example, the otherwise famous drought year of 1794, does not appear as a great si ngularity in the record. moreover, the (inter)annual distribution of days with precipitation is also an i mportant, further question to be discussed, greatly i nfluencing drought patterns (especially in case of agricultural drought). the distribution of days with pr ecipitation, presented annually, still provides some rather interesting information, even concerning the drought year of 1794. for instance, 77 days with pr ecipitation events were recorded in the manuscript concerning that year, but only 12 days were noted to be rainy in the entire spring, and no precipitation at all was recorded in march. moreover, there were no more than 4 rainy days in august. reports from other do cumentary evidence, such as contemporary newspapers (e.g. in magyar hírmondó 19 august 1794), are also available about the great drought (‘beyond any re cord’) of spring and summer on the great hungarian plain which among other evidence provide a rather detailed and clear picture about the severe lack of precipitation mainly in spring and summer, but pract ically also in winter and in the preceding years (for a short overview of scientific literature about this drought event see kiss, 2009). another interesting example can be raised from 1781: the annual distribution of days with precipitation events was rather extreme during the year. whereas the winter (1781) was remarkably rainy, the spring and the summer were rather dry. the year of 1792 was similar. despite the fact that klapka observed more than 100 days with notable precipitation, the highest number of days with precipitation events was observed during winter, while spring and summer were dry. trace precipitation although similarly to precipitation evidence, trace precipitation was probably not always recorded in time, some conclusions can be drawn, especially concerning the number of foggy days provided in the manuscript. probably the most interesting example is the extraordinary event which reflects from the written records occurred in this period: an unusually large number of days (14) with fog was recorded in timişoara during the summer of 1783. this is rather extreme in this season and shows an unambiguous anomaly compared with the other summers of the studied period (1781-1803); the number of foggy days in summer was usually between 2 or 3, but never (apart from 1783 summer) exceeded 7 (fig. 8). the unusually large number of foggy days is in good agreement with the great number of dry fogs recorded all over europe in this summer (also in the actual societas meteorologica palatina volume), which was one of the 'side-effects', impacts of the lakagígar eruption in iceland during the summer of 1783. fig.7 number of days with precipitation per year in timişoara (trace precipitation excl uded): 1781-1803 8 csernus-molnár et al. (2014) the consequences of this major volcanic eruption (lasted for 6 months) have been extensively presented in many studies, including atmospheric and weather impacts, the extreme precipitation and temperature conditions (hot summer with numerous thunderstorms, extreme winter etc.) together with related flood waves and ice jam floods during the hard winter of 1784 in europe (see e.g. stothers, 1996; self and rampino, 1998; for hungary: kiss et al., 2006; latest european overview: brázdil et al., 2010). apart from other consequences, a large number of contemporary reports can also be found concerning the dry fog phenomenon in the carpathian basin: newspapers, such as the magyar hírmondó (12. july 1783.) or the pressburger zeitung (30. july 1783.) published reports about this unusual but rather interesting phenomenon. conclusions and outlook the timişoara weather diary written between 1780 and 1803 by k. j. klapka (pharmacist) represents the southeasternmost meteorological instrumental measurements in the carpathian basin from the late 18 th century. the importance of the timişoara measurements and daily observations lies in their continuity (for 23 years, with only some days missing), construction and accuracy, and in the fact that they date back to an important period of historical climatology, namely the second part of the 18 th century (the so-called ‘maldá-anomaly’) which was famous for its temperature and precipitation extremes. due to the fact that the societas meteorologica palatina volumes were not published after 1792 and the daily measurements at buda are not available for several years after 1792 (only monthly sums are known), the measurement series of timişoara represents the single, continuous daily temperature and pressure data series from this region known at present (the series of miskolc and kežmarok are incomplete, and with some further quality problems; see csernus-molnár and kiss, 2011). after the digitalization of the measurement series of timişoara, the measured data could be compared to the results of the contemporary measurements carried out in buda, miskolc and kežmarok: strong correlations were detected between both the temperature and pressure series, which prove the further elaboration potentials of the datasets included in the manuscript. concerning the daily weather records the information on precipitation play an important role as the analysis of the number of days with precipitation provided some further parallels to the contemporary buda measurement series. moreover, the data on trace precipitation could provide some interesting information concerning the large number of foggy days observed in the summer of 1783, which might be in relation with the consequences of a major icelandic (lakagígar) volcanic eruption in 1783. references barriendos, m., martin-vide, j., pena, j. c., rodriguez, r. 2002. daily meteorological observation in cádiz – san fernando. analysis of the documentary sources and the instrumental data contect (1786-1996). climatic change 53, 151–170. doi: 10.1007/97894-010-0371-1_6 barriendos, m. – llasat, m. c. 2003. the case of the ’maldá’ anomaly in the western mediterranean basin (ad 1760-1800): an example of a strong climatic variability. climatic change 61, 191–216. doi: 10.1023/a:1026327613698 benkö, s. 1794. ephemerides meteorologico-medicae annorum 1780…..1793. vindobonae: typis alb. ant. patzowsky. tom. iv. 258, 330, 283, 323, 164 p. benkö, s. 1802. novae ephemerides astronomico-medicae annorum 1794…..1801. vindobonae: typis alb. ant. patzowsky. 204 p. fig. 8 number of foggy days in summer (1781-1803), recorded in the klapka-manuscript 18 th -century daily measurements and weather observations in the se-carpathian basin … 9 brázdil, r., valášek, h., sviták, z., macková, j. 2002. history of weather and climate in the czech lands. vol. v: instrumental meteorological measurements in moravia up to the end of the eighteenth century. brno: masaryk university. 250 p. brázdil, r., valášek, h. , macková, j. 2003. climate in the czeh lands the 1780s in light of the daily weather records of parson karel bernard hein of hodonice (southwestern moravia): comparison of documentary and instrumental data. climatic change 60, 297–327. doi: 10.1023/a:1026045902062 brázdil, r., pfister, c., wanner, h., van storch, h., luterbacher, j. 2005. historical climatology in europe , the state of the art. climatic change 70, 363-430. doi: 10.1007/s10584-005-5924-1 brázdil, r. , kiss, a. , luterbacher, j. , valášek, h. 2008. weather patterns in eastern slovakia 1717-1730, based on records from the bresslau meteorological network. international journal of climatology 28/12, 1639–1651. doi: 10.1002/joc.1667 brázdil, r., demarée, d.r., deutsch, m., garnier, e., kiss, a., luterbacher, j., macdonald, n., rohr, ch., dobrovolný, p., kolář, p., chromá, k. 2010. european floods during the winter 1783/84: scenarios of an extreme event during the ’little ice age’. theoretical applied climatology 100, 163–189. doi: 10.1007/s00704-009-0170-5 camuffo, d. 2002a. history of the long series of daily air temperature in padova (1725-1998). climatic change 53, 7–75. doi: 10.1007/978-94-010-0371-1_2 camuffo, d. 2002b. calibration and instrumental errors in early measurements of air temperature. climatic change 53, 279– 329. doi: 10.1007/978-94-010-0371-1_11 csernus-molnár, i. , kiss, a. 2011. a xviii. század végi magyarországi műszeres mérések feldolgozási és vizsgálati lehetőségei (research and study possibilities of late 18th-century instrumental weather measurement series in hungary). in: kázmér, m. (ed.). környezettörténet 2 (environmental history 2). budapest: hantken kiadó. 203–214. dall’amico, m., hornsteiner, m. 2006. a simple method for estimating daily and monthly mean temperatures from daily minima and maxima. international journal of climatology 26, 1929– 1936. doi: 10.1002/joc.1363 demarée, g. r., lachaert, p. j., verhoeve, t., thoen, e. 2002. the long-term daily central belgium temperature (cbt) series (1767-1998) and early instrumental meteorological observations in belgium. climatic change 53, 269–293. doi: 10.1007/978-94-010-0371-1_10 ephemerides societatis meteorologicae palatinae observationes. mannheim: ex officina novae societatis typographicae. tom. i-xii, 1781-1792. genersich, j. 1789-1800. meteorologische beobachtungen in dem jahr 1789. országos széchényi könyvtár, kézirattár, fol. germ. 114. glaser, r. 2008. klimageschichte mitteleuropas. 1200 jahre wetter, klima, katastrophen. darmstadt: primus verlag. 264 p. kern, z., popa, i. 2009. assessing temperature signal in x-ray densitometric data of norway spruce and the earliest instrumental record from the southern carpathians. journal of environmental geography 2(3-4), 15–22. kiss, a., sümeghy, z., danku, gy. 2006. az 1783-1784. évi szélsőséges tél és a maros jeges árvize (severe winter of 17831784 and the ice flood on the maros river). in: kiss, a., mezősi, g., sümeghy, z. (eds.). táj, környezet és társadalom / landscape, environment and society. szeged: szte. 353–362. kiss, a., sümeghy, a., fehér, z. zs. 2008. a maros 18. századi áradásai és egy jellemző téli árvizének területi hatásai (18thcentury floods of the maros river and the areal consequences of a winter flood). in füleky, gy. (ed.) a táj változásai a kárpátmedencében. az erdélyi táj változásai(landscape changes in the carpathian basin. changes of the transylvanian landscape). gödöllő: szent istván egyetem. 94–100. kiss, a. 2007. „suburbia autem maxima sui in parte videntur prorsus esse deleta” , danube icefloods and the pitfalls of urban planning: pest and its suburbs in 1768-1799. in: kovács, cs. (ed.) from villages to cyberspace. szeged: university press. 271– 282. kiss, a. 2009. historical climatology in hungary: role of documentary evidence in the study of past climates and hydrometeorological extremes. időjárás 113(4), 315–339. kiss, a. , csernus-molnár, i. 2008. időjárási viszonyokhoz kapcsolható szélsőségek területi vonatkozásai a temesi bánságban: 17801800 (areal consequences of weather-related extremes in the temesi bánság/banat area: 1780-1800). in füleky, gy. (ed.) a táj változásai a kárpát-medencében. az erdélyi táj változásai (landscape changes in the carpathian basin. changes of the transylvanian landscape). gödöllő: környezetkímélő agrokémiáért alapítvány-szent istván egyetem. 101–106. kiss, a., sümeghy, z., danku, gy. 2006. az 1783-1784. évi szélsőséges tél és a maros jeges árvize (the severe winter of 1783-1784 and the ice-flood of the maros river). in kiss, a., mezősi, g., sümeghy, z. (eds.) táj, környezet és társadalom / landscape, environment and society. szeged: university press. 353–362. klapka, c.j. 1803. observationes thermometricae et barometricae a 1a septembris 1780. usque ultimam decembris 1803. temesvarini factae per c. j. klapka. eötvös loránd university library, manuscript and rare book collection, cat. number e 40. klapka, gy. 1886. emlékeimből (from my memories). budapest: franklin társulat. 4–5. réthly, a. 1970. időjárási események és elemi csapások magyarországon 1701-1800-ig (weather events and natural disasters in hungary in 1701-1800). budapest: akadémiai kiadó. 519-565. self, s., rampino, m.r. 1998. the relationship between volcanic eruptions and climatic change: still a conundrum. eos 69/6, 74–86. stothers, r.b. 1996. the great dry fog of 1783. climatic change 32, 79–89. doi: 10.1007/bf00141279 strömmer, e. 2003. klima-geschichte. methoden der rekonstruktion undhistorische perspektive. ostösterreich 1700 bis 1830. forschungen und beiträge zur wiener stadtgeschichte 39. vienna: deuticke. p. 325. szinnyei, j. 1900. magyar írók élete és munkái (life and works of hungarian writers). budapest: hornyánszky viktor. vol. 6. 466. szőkefalvi-nagy, z., zétényi, e. 1965. egy xviii. századi magyar meteorológus: benkő sámuel miskolci orvos (an 18 th -century hungarian meteorologist: sámuel benkő, the doctor of miskolc). borsodi szemle 9, 51–56. journal of environmental geography journal of environmental geography 6 (3–4), 21–29. doi: 10.2478/jengeo-2013-0003 issn: 2060-467x investigation of daily natural and rapid human effects on the air temperature of the hajnóczy cave in bükk mountains beáta muladi * , lászló mucsi department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: muladi@geo.u-szeged.hu research article, received 28 august 2013, accepted 7 october 2013 abstract the aim of this study the authors measured and analyzed the effect of the exterior daily temperature change on the interior temperature in a dripstone cave visited by cavers exclusively. the measurement was carried out in the hajnóczy cave located in the southern part of bükk mountains in hungary. although only one entrance is known, there are more evidences for the strong effect of exterior conditions on the interior processes like temperature fluctuation and dripstone development. using high resolution wireless digital thermometer sensor network the air temperature and air humidity were measured in 32 points in every 10 minutes for long time but now the data of a 8-days period were analyzed. based on these data different zones of the cave could be separated and during summer conditions the climatic variability of the entrance transitional and deep cave zone was described. based on statistical analysis of spatial information significant correlation was found between the exterior temperature fluctuation and that of such a cave chamber, which is relatively far from the cave entrance. this fact proves that existence of a fissure system which is permeable for air but not passable for cavers. during the measurement the human effect was also analyzed and 0.3-0.6 °c temperature rising was recognized for a short time. because of the surface vicinity the effects of the environmental change can have sensible impact on the cave and its natural phenomena. among others temperature rising, air humidity decreasing were detected in present study. keywords: cave temperature, wireless sensor network, hajnóczy cave introduction the macroclimate is the determining factor for karst development and formation of surface and subsurface processes. beside the general macro scale processes, however the microclimate factors have important effects on ecological mechanism and other natural processes like corrosion, erosion, dissolution. generally it can be stated, that the microclimate has an impact on cave morphology, biology (flora and fauna), and management. the scientific research started mainly in mid 20 th century with the investigation climate of caves and its influence upon cave organisms (poulson and white, 1969). jakucs (1977) investigated the connection between microclimate factors and chemical processes in soil and limestone layer. de freitas and littlejohn (1987) analysed the impact of cave microclimate upon sensitive cave fauna and cave management. the 3-zone model has been developed to describe the general zones of climatic variability within a cave (cropley, 1965; poulson and white, 1969; fodor, 1981). according to this 3-zone model, a twilight zone exists near the cave entrance with greatest variability in microclimate parameters. moving from the entrance towards the interior of the cave, the influence of exterior climatic conditions diminishes and a middle zone exists in complete darkness with some variability in cave microclimate. further in the cave, at the rear, a deep cave zone exists with constant microclimatic conditions (gamble et al., 2000). the great improvement achieved in the last decades are mainly due to the new technology and particularly to the inexpensive data loggers which record unattended a great number of data. at the same time, the financial support of some show caves to carry on environmental researches and to evaluate the visitors’ capacity was instrumental in the development of cave climatology (hoyos et al., 1998; de freitas et al., 2006; lario and soler, 2005). the high resolution microclimate study can give very useful spatial information about the air mass movement not only in the show caves but in such caves which are used and investigated only by researchers (cigna, 2002). new entrances, new interior passages can be found according to the analysis of detailed spatial information based on microclimate measurement. study area the hajnóczy cave is located on the south-western part in bükk mountains (fig 1). the cave was formed in middle triassic ladinian and upper triassic karnian cherty grey limestone. the cave entrance can be found on the odorvár hill slope at 475 m above the sea level. http://en.wikipedia.org/wiki/triassic 22 muladi and mucsi (2013) odorvár (574 m) is a limestone hill situated in the western side of the valley of the hór creek. the “odor” word means area with hollows. the total length of its corridors is cca. 4257 m, the vertical difference between the highest and deepest points is 125 m (fig 2.). fig. 1 bükk mountains (mucsi l.) fig. 2 hajnóczy cave location on topographical map (muladi b.) the air temperature measurement was carried out in the two morphologically distinguishable parts of the cave (varga, 2003). the first investigated area was the entrance part of the cave, which can be characterized by narrow corridors. after this part the cave halls were formed along bedding planes by karstic corrosion. this kind of passage system, which is rich in narrow corridors, continues from the cave entrance through the house-top (háztető) and ruin hall (rom-terem) to the great hall (nagyterem). this part can be described as a labyrinth, in which the distance between the bottom and ceiling of the halls is continuously increasing. further part of the cave can rather be described as part of large halls formed by erosional processes and by small corridors which connect these halls. this part contains the leyla, and the very narrow passage almond (mandula) called after its cross section shape. after the almond passage the gallery of 10-15 m high hall follows. this is one of the most beautiful halls of the cave because of the uncountable stalagmites. the largest hall of the cave called as the giant hall is the last hall on this west-eastern part of the cave. the horizontal dimension of this hall is 62*16 m, while the vertical dimension is 10-12 m. the ceiling of the giant hall is very near to the surface as shown by the tree roots that can be seen on the walls. the western part of the cave can be found in limestone layers which are covered by older dark grey shale. the hajnóczy cave was discovered in 1971, and the mapping and the scientific investigation started immediately after its discovery. the first air temperature measurement campaign was executed by miklós, g. and városi, j. from 1975 to 1977. according to their measurements the air temperature ranged from 8.5 °c to 10.5 °c. the relative humidity was higher than 98% on average, but there were wetter and drier halls in the cave. up to now is observable the fact that the halls near to the surface are drier, while the halls and corridors deep under the surface are more wet. if the difference between the cave and surface air temperature is about 10 °c, then the amount of the moving air is cca. 0.4 m 3 /s. the velocity of the air ranges from 5 to 25 cm/s, and at the entrance part it was 20-40 cm/s, while the air flow impulsion reached 50 cm/s (miklós, 1978). data and methods present research activity started in december 2011. almost 2 years of continuous measurements have resulted in detailed information about the annual trend of the cave air temperature and main features of cooling and warming processes (muladi et al., 2012). aim of our study was to determine the spatial profile of air temperature of the cave developed during summer air circulation period in july 2012. horizontal air movement and vertical lamination could be identified because digital equipment was installed in the cave at the same time, in different halls and corridors. the air humidity was also measured beside the air temperature. fig. 3 uc mote mini (muladi b.) investigation of daily natural and rapid human effects on the air temperature of the hajnóczy cave in bükk mountains 23 uc mote mini low power wireless sensor module developed at the university of szeged was used for our measurements (fig. 3). this device promotes ieee 802.15.4/zigbee wireless communication protocol in order to realize a low data rate. the radio module can operate at a data rate of 250kbps in ism 2.4ghz band. the control is regulated by 16 mhz atmel atmega128rfa1 microprocessor with 128kb ram. several types of sensors are integrated into this device. fig. 4 hajnóczy cave map and devices location the accuracy and the scale of sht21 temperature and the humidity sensor are ± 0.3 °c, 0.01 °c and ± 2.0% rh, 0.04 % rh, respectively. data collection can be realized with 2mb external flash tinyos, which is a small open-source energy-efficient software operating system, supporting large scale self-configuring sensor networks. the device is powered by lir2450 battery (senirion, datasheet sht21). during our study, data were recorded in every 10 minutes. the sensors could be used for more than 3 months without battery replacement. the data obtained every 10 minutes were evaluated using a matrix of correlation coefficients. first, data were averaged according to hour and day, resulting in a new dataset. then these data were processed with pair wise correlation coefficients in order to investigate the direct and indirect relationships among cave airflows. the temperature and relative humidity of cave air were detected using 32 sensors (14 of them can also measure air pressure) in hajnóczy cave. in each case one of the sensors was placed near the cave entrance to measure surface temperature (fig. 4). results according to the direction of the air movement the hajnóczy cave is rather a through cave then a big cave, apart from the fact that it has only one known entrance. one part of the main halls is situated in relatively higher position to the entrance and these halls are near to the radiated southern hill slope. so during summer meteorological conditions, when the exterior air mass is always warmer than the air in the cave, the cooler and heavier air mass of the cave is continuously flowing out through the cave entrance. at the same time warmer exterior air moves to the cave through the fissure system in the limestone layers. in this case 3-4 °c difference can be measured in the air temperatures in different parts of the cave. the minimum air temperature was 8.2 °c during the summer measuring period which is equal to the annual mean temperature of this hilly region. because of the insulating effect of the buried limestone layer (in some places its thickness is less than 4-5 m) the maximum air temperature was higher than 11.2 °c. in 197577 the air temperature measurement was carried out by analogue instruments but the results can be compared to our data which were collected by digital thermometers. the air temperature ranged from 8.5 to 10.5 °c that time, which means that there is no significant difference between the data of these two datasets. the 0.7 °c difference between the maximum values can be the reason for the higher monthly mean temperature on july 2012 (24.1 °c) compared to the lower monthly temperatures measured in 1975-77 (20.6-22 °c). the results of the analysis of air mass movement and the effect of the exterior air to the air temperature of the cave is presented in this paper. the results are based on the data which were collected from 01 st july to 09 th july 2012. surface, entrance and housetop, smoky one thermometer was installed near to the cave entrance to measure the temperature of the exterior air mass. during the measuring period the maximum values ranged between 33 and 35 °c, while the minimum values changed between 13 and 23 °c (fig. 5b). during the summer air circulation period the air mass is flowing out from the cave through the total section of the entrance. the passages near the entrance are sink-like, because the surface conditions have an effect on the air temperature just within the first few meters from the entrance. the influence of the convection is so intensive in this part of the cave, that the effect of a visiting group could not be measured. after the entrance part, where 3-4 smaller halls are located, the velocity of the air mass decreases, so vertical lamination of the air mass can be proved by the decreasing air temperature. the sensor located very near to the entrance measured 10.810.9 °c with slightly traceable daily fluctuations (no. e1 on fig. 5b). the following sensor detected almost with 2 °c lower air temperature about 5 m from the entrance. the graph of this data also show daily fluctuation, but the difference between the minimum and maximum values is less than 0.1 °c. at the housetop the air temperature was changed between 8.2 and 8.3 °c without any daily fluctuation (no. e3 on fig. 5c). the lower and the upper smoky halls are located east to the housetop in the labyrinth-like part of the cave near to entrance. they called after the black colour walls, which might be the results of the manganese content of the stalagmite coverage. 24 muladi and mucsi (2013) the upper smoky hall is relatively dry because of its closeness to the surface. the lower smoky hall has a narrow connection to the upper smokey hall, and it is a “bag-like” place, where constant air temperature (8.4 °c) was measured (no. e4, e5 on fig. 5c). the ruin hall is situated west to the housetopbetween entrance zone and depot hall as transitional zone between them. two sensors were installed in this hall (no. e6, e7 on fig. 5a), and the air temperature ranged from 8.4 to 8.55 °c in the analysed period without any daily fluctuation. the sensors were located near to the cavers pathway so human heat radiation sometimes increased the air temperature with 0.1-0.2 °c (no. e6, e7 on fig. 5c). the position of the ruin hall is similar to the lower smokey hall; both are big-like room in which the air temperature does not change in a short period. the ruin chamber is connected with the great chamber by the depot. the depot is the first room in which the cavers can deposit their measuring and research equipment onto a horizontal surface safely. from the depot the pathways forks, one path leads to the great chamber, the other one goes back to the lower smoky room through the flat chamber. the depot steeply leads down from the ruin chamber to the great chamber. few years ago the cavers climbed out a chimney-stack over it. this almost vertical passage was called white fox chamber. during the summer measurement 2 sensors were deposited in depot (no. d2, d3 fig. 6a), one on the top and one on the bottom. a third sensor was hanged in the middle part of the flat chamber (no. d1 fig. 6a). cold air mass (8.3 °c) was in stable situation on the bottom without any daily fluctuation (see graph labelled d2 on fig. 6b), while the warmer air temperature was measured on the top of this chamber (8.8 °c). the flat hall (lapos-terem) is located further on the entrance but the temperature data of the sensor situated in this hall (d1 on fig. 6b) show very strong influence of surface. the daily fluctuation of the air temperature is not so high (δt=0.12 °c) but it was detectable by the sensor. peaks on the graphs are the effects of the visiting groups on air temperature. for a short period the air temperature was higher with 0.1 and 0.3 °c in the lower smokey hall after visits of 3 cavers on 6 th and 8 th july 2012 (fig. 7). the flat hall has smaller air volume because the average height of this hall is about 70 cm so the human effect on air temperature was more significant ((δt=0.2-0.4 °c) after the visiting of 4 persons on 7 th july (fig 7). it was very surprising to observe clear daily temperature fluctuation during summer air circulation condition in the flat hall which is located far from the cave’s entrance. miklós and városi supposed that the air mass is moving from the giant hall toward the entrance (miklós, 1978). the distance between the giant hall and the flat hall is large and the air mass velocity in the cave is low consequently air convection from the giant hall would not have an effect on the air temperature of the flat hall. subsequently, there has to be a connection between the surface and the flat hall through an unknown entrance or through the fissure system and cave passages. fig. 5 sensors location (a) surface and entrance (b), housetop, smokey and ruin hall (c) temperature data (°c) http://szotar.sztaki.hu/en/search?searchword=chimney-stack&fromlang=eng&tolang=hun&outlanguage=eng investigation of daily natural and rapid human effects on the air temperature of the hajnóczy cave in bükk mountains 25 to prove our assumption first of all the correlation between the surface and flat hall’s temperature was calculated. foremost the graphs were smoothed using following equation: ti=(sum ti-j)/11 j=-5,…,5 where ti = average temperature in a given time (i) the daily maximum temperature value in the flat hall was reached at a later time than the maximum value of surface temperature. this time-lag was fluctuating daily as a function of the difference between the daily maximum and minimum surface temperature. the minimum delay was 1.3 hour, and the maximum delay was 4.8 hour. the correlation between for the daily temperature values of the flat hall and surface was calculated using the sliding cross correlation method. the correlation coefficient (r) expresses the strength of the relationship between the two variables. , )()( )()( 22       yx yx mymx mymx r where mx is the mean of the x, and my is the mean of the y variable. fig. 6 sensor location (a) depot and great hall (b) and leyla and almond (c) temperature data (°c) fig. 7 number of cavers in the cave (source: leader of the hajnóczy józsef speleological research group) 26 muladi and mucsi (2013) the correlation coefficient (r) can be ranged between -1 and 1. if the value is close to -1 or one there is a strong connection between the values, if it is close to 0 the connection is random. a positive value indicates a positive connection, while a negative value indicates a negative relationship (péczely, 1979). the 8 day analysing period was divided into 8 segments considering the measured time-lags, and then the correlation coefficient was calculated for the daily values. according to the cross-correlation method, the maximum value of the daily correlation coeff icient ranged between 0.85 and 0.96 (table 1), consequently there is a significant connection between the daily temperature values of the flat hall and that of the surface. the highest correlation coefficient was shown at different time-lags in this period. miklós and városi stated 35 years ago that there can be strong connection between the highest outer air temperature value and the value of the cavern air velocity. according to our statistical analysis a strong opposite relationship exists between the difference of the maximum and minimum surface air temperature (δt) and the length of time-lags (ltl). the following function defines the numerical connection between time-lag (dependent variable) and δt. (fig. 8) ltl= -0,4279 δt +8,0142 the correlation coefficient r is equal to -0.64, which shows negative correlation between these parameters. fig. 8 time difference based on sliding correlation and daily surface temperature difference we proved that the air temperature is affected by the outer air mass in the flat hall, which is located far from the entrance. if the air is moving out from the cave through the entrance there has to be one or more paths in which the outer air masses can reach into the cave. one of these paths might be the passages which connect the upper smokey hall with the flat hall. the other more probable pathway is the white fox chamber, which is a vertical passage above the depot hall. during the discovering of this chamber, the researchers found animal bones. these bones were washed into the cave many years ago, indicating that there has to be an open fissure system somewhere above the currently known entrance. the thickness of the limestone layers has to be less than 5-6 m. this value is based on the data of the cave map of high accuracy and digital elevation model calculated from stereo aerial imageries. the spatial distance between the supposed end of the fissure system on the surface and the sensor location is cca. 40-50 m, therefore the velocity of the passing air has to be cca.0.5-1 cm/s if we calculate by the known timelags (1.3-4.8 hours) (fig. 9). fig 9 hajnóczy cave atmospheric circulation the great chamber is the largest chamber in the cave’s first zone (48 m long, 14 m wide and 5-8 m heigh). there are few stalagmites in it and calcite crystals on the wall of a dried out pond (fig. 10). daily fluctuation of air temperature can be seen on the graph belongs to the data measured in this chamber (no. d4 fig. 6b), so we can take it that the exterior air can directly reach this chamber through the fissures above it. table 1 the differences of the time and temperature date 1-jul 2-jul 3-jul 4-jul 5-jul 6-jul 7-jul 8-jul time difference based on sliding correlation 2.5 4.8 4.1 2.1 4.5 1.3 1.7 1.3 daily surface temperature difference 11.3 10.6 10.2 9.8 12.1 15.9 13.4 14.4 maximum sliding correlation 0.90 0.94 0.86 0.85 0.89 0.85 0.96 0.88 http://szotar.sztaki.hu/en/search?searchword=consequently&fromlang=eng&tolang=hun&outlanguage=eng http://szotar.sztaki.hu/en/search?searchword=consequently&fromlang=eng&tolang=hun&outlanguage=eng investigation of daily natural and rapid human effects on the air temperature of the hajnóczy cave in bükk mountains 27 fig. 10 great chamber calcite crystals on the wall (mucsi l.) the leyla and the almond passage are found on the north eastern part of the great chamber. this is the way to the main section of the cave, what contains the for example the grand canyon and the tsitsogó on its western part and gallery and giant chamber on the eastern part of it. the almond passage was closed by limestone and shale agglomerate for thousands years until 1977, when the cavers broke through that (fig. 11). the highest value of the velocity air convection can be measured in the almond passage in the hajnóczy cave, because large volume of air mass has to move through on a tunnel whose cross section is less than 0.25 m 2 . fig 11 almonds passage (miklós g.) miklós and városi measured 20-40 cm/s air velocity in almond in 1977. the air is flowing from the gallery toward the entrance in summer. the air temperature ranged between 8.7 and 9,1 °c in july 2012 with a fine daily fluctuation. because of the tight cross section of the almond passage the temperature increasing effect of the visitors (cavers) can be measured and the rate of temperature rising is 0.5-0.6 °c. gallery the gallery is one of the most beautiful parts of the cave. its dimensions are: 70 m long, 1-8 m wide and 4-13 m high (fig. 12). the reason for the stalagmite formation is the vertical position of thin limestone layers. large amount of infiltrating saturated karst water can get into the cave along the limestone layer and after the dropping from the ceiling to the bottom of the hall the stalagmites (columns) grow bigger. miklós and városi measured a little bit higher air temperature in the gallery in 1975 than in the entrance part, but the position of the measuring equipment is unknown. therefore 7 sensors were utilized in our measurement in 2012 and vertical lamination of the relatively calm air mass was detected (fig. 13). the measured air temperature values are higher than that of the deeper parts of the cave, because upper part of this chamber is not so far from the eastern slopes of odorvár. fig. 12 gallery stalagmite formation (mucsi l.) fig. 13 gallery’s sensors location (a) and temperature data (b) (°c) 28 muladi and mucsi (2013) giant hall the entrance to the giant chamber can be reached from the eastern end of gallery through huge collapsed rock blocks. almost whole skeleton of ursus deningeri was found near to these blocks in the upper gallery under a 3-5 cm thick dripstone layer. this fact also proves the vicinity of the surface. the giant chamber is the largest chamber of the hajnóczy cave (63 m long, 16 m wide and 14 m high). the giant chamber is the driest part of the cave because it has very small catchment area, and the air humidity is lower because of the relatively high air temperature (10.67-11 °c). this is the reason of the thin limestone layer. the tree roots can reach the ceiling of the giants hall (fig 14). the reason of this is that there is a thin limestone layer above this cave chamber proved by the tree root hanging from the ceiling. about 4 m 2 area was covered with bat’s guano in 1980’s, when this chamber was discovered and few flying and hanging bat can be seen in this part of the cave which is also the evidence of the surface vicinity. because of the low air humidity and few seeping water some of the formerly “living” dripstone phenomena died now. according to the maximum temperature values (11 °c) measured in 2012 compared to the data from 1975 (10.4 °c) the temperature rising can be recognized. because of the proved strong connection with the surface the cause of this temperature rising is the effect of very hot summers of last decades. unfortunately due to the lack of the long term temperature measurement the potential effect of the global warming can be hardly proved. conclusion temperature observations were collected inside the hajnóczy cave in order to characterize microclimate of a temperate zone cave system in summer condition. the applied wireless sensor system operated well. cavers affected rapid temperature rises were detected and small scale daily fluctuation was also revealed. some general characteristics of cave system can be drawn from these observations that concur with existing temperate cave microclimate theory. the first characteristic is that external atmospheric disturbances can affect temperatures of cave system. the daily fluctuation can be observed far from the entrance, which proves new unknown connection of this chamber with the surface. the former air circulation system described on min 1970’s by miklós and városi was updated according to the measurement carried out in 2012. the second characteristic is that interior air mass is laminated on bigger chambers of the cave where the natural ventilation does not work. thirdly it has been recognized that the exterior warm air can reach the upper passages of the cave through the fissures in limestone layer and rises the mean air temperature of the cave (8.5 °c) with 2.5 °c in the giant chamber. therefore the air circulation of the cave system is rather similar to the air circulation of a multi-entrance system. because of this open system the cave is very sensitive to the effect of the rapid climatic processes and to global climate change in long term. acknowledgement we would like to express our appreciation to all those who contributed to our work. special thanks goes to dr. miklós maróti, zoltán csépe, csaba varga, ákos mező and károly barta for their help. the instruments were provided by the támop4.2.2/08/1/2008-0008 supported by the european union and co-financed by the european social fund this research was supported by the european union and the state of hungary, co-financed by the european social fund in the framework of támop 4.2.4. a/2-11-1-2012-0001 ‘national excellence program’. references cigna a.a. 2002. modern trend in cave monitoring, acta carstologica 31 (1), 35–54. cropley, j.b. 1965. influence of surface conditions on temperatures in large cave systems. nss bulletin 27 (1), 1–10. de freitas, c.r., littlejohn, r.n. 1987. cave climate: assessment of heat and moisture exchange. international journal of climatology, 7, 553–569. de freitas c.r., littlbjohn r.n., clarkson, t.s, kristament, i. s. 2006. cave climate: assessment of airflow and ventilation journal of climatology 2 (4), 383–397. fodor, i. 1981. a barlangok éghajlati és bioklimatológiai sajátosságai (the climatic and bioclimatological fig. 14 giant hall’s sensors location (a) and temperature data (b) (°c) http://onlinelibrary.wiley.com/doi/10.1002/joc.v2:4/issuetoc investigation of daily natural and rapid human effects on the air temperature of the hajnóczy cave in bükk mountains 29 characteristics of the caves), akadémia kiadó, budapest, 168–169. gamble, d.w., dogwiler, j.t., mylroie, j.e., 2000. field assessment of themicroclimatology of tropical flank margin caves. climate research, 16, 37–50. hoyos, m., soler, v., can˜ averas, j.c., sa´nchez-moral, s., and sanz-rubio, e., 1998. microclimatic characterization of a karstic cave: human impact on microenvironmental parameters of a prehistoric rock art cave (candamo cave, northern spain): environmental geology, 33, 231–242. hoyos, c.d., agudelo, p. a., webster, p. j., curry, j. a. 2007. deconvolution of the factors contributing to the increase in global hurricane intensity, science 312, 94–97. jakucs, l. 1977. morphogenetics of karst regions: variants of karst 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(ed.) magyarország fokozottan védett barlangjai mezőgazda kiadó, budapest, 200–204. modelling the impact of tillage on water quality for sustainable agricultural development in a savanna ecological zone, kwara state, nigeria journal of environmental geography 14 (1–2), 15–23. doi: 10.2478/jengeo-2021-0002 issn 2060-467x modelling the impact of tillage on water quality for sustainable agricultural development in a savanna ecological zone, kwara state, nigeria toluwalope mubo agaja1*, lanre tajudeen ajibade1, micheal olufemi agaja2 1department of geography and environmental management, faculty of social sciences, university of ilorin, p.m.b. 1515, ilorin, kwara state nigeria. 2national centre for agricultural mechanization (ncam), km-20, ilorin-lokoja highway, idofian, ilorin, kwara state nigeria. *corresponding author, email: specialgel@yahoo.com, agaja.tm@unilorin.edu.ng research article, received 6 november 2020, accepted 5 april 2021 abstract the aim of the study was to examine the effects of tillage methods on surface runoff and model the pattern and processes of surface water pollution associated with tillage methods using soil water assessment tool (swat). this model was designed to predict the impact of land management practices on water, sediment, and varying tillage types in watersheds over two planting seasons. traditional heap (t), plough/harrow (ph), plough/harrow/ridge (phr) and no-tillage (nt) methods commonly used in the study area were applied to experimental plots at unilorin teaching and research farm and national center for agricultural mechanization, idofian (nigeria). using randomized complete block design (rcbd), each treatment had three replicates making 12 experimental plots at each location for the 2015 and 2016 planting season. nine biophysical parameters were purposively selected, examined and modelled. the study revealed that four of nine biophysical factors (sediment yield: 10.54 t/ha; groundwater discharge: 174.45 mm; organic nitrogen: 62.62 kg/ha, and nitrogen in surface runoff: 5.15 kg/ha) were higher for traditional heaps, while three parameters (surface runoff: 374.42 mm; evapotranspiration: 752.78 mm, and soil loss: 1.05 kg/ha) were higher under plough/harrow and plough/harrow/ridge cultivation practices. the study concluded that tillage methods have impact on water quality. however, plough/harrow has comparatively more favorable effect on the contribution to surface runoff. it is therefore recommended that this type of tillage should be adopted to reduce water pollution and for sustainable environment. keywords: tillage, environment, sustainability, water quality, pollution introduction agriculture is an essential human activity that facilitates food production. for a long time, the increasing demand for food was met by the extension of cultivated area under cultivation. one of the consequences of crop production is the clearing of natural vegetal cover which in turn exposes the cleared land to weathering processes and degradation. such weathering processes include soil erosion, leaching of nutrients and change in nutrient profile of the soil, which increase the pollution of fresh water sources. tillage is the agricultural preparation of the soil by mechanical, draught-animal or humanpowered agitation involving activities such as ploughing, digging, overturning, shoveling, hoeing and raking (aina, 2011) while conservation tillage is an option for maintaining soil health and the surrounding environment for intensive agriculture, especially in the tropical climate (sayed et al., 2020). the soil tillage systems influence the soil structure and can have considerable impact on the environment. this substantially affect water quality, nutrient availability, crop yield, sediment transport, pesticide distribution, air quality and greenhouse processes. the effects of soil structure on agricultural production range on scales from soil productivity and sustainability at a local scale, to water quality and landscape at a regional scale, and water and energy balance and greenhouse effect at a global scale (derpsch, 2007; hobbs, 2007). agricultural practices have been a major contributor to water pollution more than any other single source (gliessman, 1998). overland flow from farms can contain lots of sediment, pesticides, and fertilizers as well as animal waste products. the leading cause of decreased water quality in lakes and estuaries is agricultural nutrient pollution, whereas agricultural fertilizers are the dominant source of nutrient pollution in any watershed (mateo-sagasta et al., 2017). most crops remove more nitrogen from the soil than any other nutrient, so more nitrogen is applied as fertilizer. about 50% of the nitrogen fertilizers applied to crops is not taken up by the plant and remains as residue in the fields. these residues are carried by runoff and easily leach into groundwater especially when fields are irrigated (hallberg, 1987). also, 75% of the sediment in watercourses is estimated to have come from agricultural lands (anthony and collins, 2006). typically, runoff water contains sediment, dissolved nutrients, and possibly some chemicals from conventional tillage methods. water runoff could be mailto:specialgel@yahoo.com mailto:agaja.tm@unilorin.edu.ng 16 agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. reduced by conservation tillage, thereby increasing infiltration of water into the soil. one immediate and obvious result of conservation tillage is improved surface water quality. stimulation and excessive growth of algae and other aquatic vegetation may occur as a result of agricultural runoff, causing severe water quality problems. overgrowth of algae, in particular, causes oxygen depletion that may kill fish, and also leads to taste and odor problems for drinking water supplies. sediments from cropland erosion may also increase the turbidity (cloudiness) of water, impairing fisheries (devlin and barnes, 2009). li and guo (2020) reported that the total nitrogen loads are much higher than the total phosphorus loads from agricultural lands. the land use types showed great pollution loads resulting from various significant spatial differences: agricultural lands have the greatest total nitrate and phosphorus load per unit area, followed by grasslands. forested lands have the least pollution load per unit area. water-borne diseases like diarrhoea has killed more than 100,000 children under five years of age in nigeria as reported by the united nations children’s fund, and 90 % of those deaths were directly attributed to unsafe water and sanitation (onwuzoo, 2020). also, galadima et al. (2011) reported that the most common causes of illness and death are water related diseases affecting mainly poor inhabitants in the local communities. several cases of death due to water related diseases have been reported: in october 2010, 1191 deaths of cholera from 29115 cases was reported in 15 of the 36 states in nigeria, including the federal capital territory, abuja (galadima et al., 2011). it was observed that the outbreak is still in existence in new areas due to continuous water pollution. agricultural diffuse water pollution remains a notable global pressure on water quality, posing risks to aquatic ecosystems, human health and water resources and as a result legislation has been introduced in many parts of the world to protect water bodies. due to this, water quality models such as soil water assessment tool (swat) have been increasingly applied to catchments to better understand the pattern and process of water pollution from water sheds in different regions which will help identify and provide mitigation options that can be introduced to reduce agricultural diffuse water pollution and improve water quality (taylor et al., 2016). according to gassman et al., (2014), one of the most widely used water quality watershedand river basin-scale models worldwide is the swat model. it can be useful extensively for a broad variety of hydrologic and/or environmental problems. some of the major advantages of the use of swat and its wide acceptance internationally can be attributed to its flexibility in addressing water resource problems comprehensive online documentation and supporting software can be adapted for use for specific application needs. shen et al. (2013) applied the swat in the three gorges reservoir basin (china) to estimate nitrogen and phosphorus loads and identify causal factors. they found the paddy (rice) fields and non-irrigated cultivated areas to be the most important sources of both nutrients. einheuser et al. (2012) simulated nutrient concentrations in the saginaw river (usa) with swat, and linked them to indicators of stream health. the results of the study suggest that nutrient concentrations have the highest influence on stream health. this combined modelling system was used to predict the effect of various conservation practices on stream health. tillage is the agricultural preparation of the soil by mechanical, draught-animal or human-powered agitation, such as ploughing, digging, overturning, shoveling, hoeing and raking. the term tillage used broadly, embraces all operations of seedbed preparations that optimize soil and environmental conditions for seed germination, seedling establishment and crop growth. tillage includes mechanical methods based on conventional technologies of ploughing and harrowing, weed control using herbicides and fallowing with cover crops controlled by direct seeding through its residue mulch according to ohu (2011). there are two main types of tillage systems which are conventional tillage and conservation tillage. conventional tillage is any tillage and planting system that leaves less than 15% residue cover after planting or less than 560 kg/ha of small grain residue equivalent throughout the critical wind erosion period as proposed by ctic (2004). firstly, it includes systems such as mechanized tillage involving the mechanical soil manipulation of an entire field, by ploughing followed by one or more harrowing. the degree of soil disturbance depends on the type of implement used, soil and intended crop type. secondly, traditional tillage is practiced mostly by manual labor in the humid and sub-humid regions of west africa, and in some parts of south america. it uses native tools which are generally few and simple, the most important are the cutlass and hoe which come in many designs depending on function as observed by aina (1993). the second type of tillage is conservation tillage which is any tillage and planting system that covers 30% or more of the soil surface with crop residue after planting, to reduce soil erosion by water is conservative tillage (ctic, 2004). there are many variations of conservation tillage systems covering abroad spectrum of farming methods primarily aimed at reducing soil disturbance, conserving and managing crop residue to reduce erosion. ohu (2011) divided conservation tillage practices into no-tillage, ridge tillage, strip tillage and the mulch tillage having varying practices and application but with the focus of conserving the resources on the soil. alternative land management practices such as conservation or no-tillage, contour farming, terraces, and buffer strips are increasingly used to reduce nonpoint source and water pollution resulting from agricultural activities. models are useful tools to investigate effects of such management practice alternatives on the watershed level. however, there is a lack of knowledge about the sensitivity of such models to parameters used to represent these conservation practices (european environment agency, 2005, as cited by taylor et al., 2016). consequently, the effort at reducing pollution has not been too successful since a agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. 17 little understanding exists on sources and processes of pollution especially in watershed areas. though there is a lot of information on tillage studies, the aspects that characterize the complexity of tillage systems and its impact on water quality is yet to be fully researched. therefore, the aim of the study was to examine the effects of various tillage methods on surface runoff and to model the pattern and processes of surface water pollution associated with tillage methods using soil water assessment tool (swat). study area the study was carried out at the university of ilorin teaching and research farm, ilorin (utrf) and national centre for agricultural mechanization (ncam), idofian kwara state (nigeria) respectively (fig. 1). the climate of the study area falls within the tropical hinterland climatic zone, having a dry season occurring between november to april while the rainy season is between may and october. occasionally, there could be an earlier beginning of the rainy and the dry season (mustapha, 2008). the dry season is characterized by low amount of rainfall, high temperature and mean monthly rainfall total of about 360 mm. the mean annual evaporation is in the range of 1000-1200 mm, the humidity ranges between 30-80%. relative humidity is high during the rainy season and low in dry season. the temperature ranges between 20-30 oc (adelana and olasehinde, 2004). the type of rainfall experienced is convectional storms, sometimes very windy. the heaviest rainfall is usually recorded between june and early august. there is a short spell of drought between august and early september (oyegun, 1983; olaniran, 2002). the experimental sites are located in the guinea savannah grassland and characterized by the presence of fire tolerant woody shrubs and trees which are biologically suited to withstand dry conditions. the plants are about 12 m high with grass of about 1.5-2.5 m in height while some parts of the study area have some rainforest trees (such as acacia trees, locust bean etc; jimoh and ajao, 2009). the type of soil is ferruginous tropical soil and the parent material consists of micaceousschists and genesis of basement complex origin which are rich in ferromagnesian minerals. the soil formation is characteristic of the geology of the study area exhibiting jurassic, pan african and precambrian geological structure (ahaneku, 1997). the utrf and ncam experimental sites are drained mainly by oyun river (fig. 2), which takes springs at ita-oregun (in osun state) and flows through otan-aiyegbaju (in osun state) to offa and finally to ilorin where it is dammed at the university of ilorin main campus. the catchment of oyun river is located between latitudes 9º50’ and 8º24’ north and longitudes 4°38̍ and 4°03̍ east. its total catchment area is 800 km2 with a length of 71.4 km and it lies within kwara state. the first experimental site (ncam) is located at the upper catchment area of the river, while the second experimental site (utrf) is located at the lower catchment area of river oyun that bounds it to the west (fig. 2). the drainage pattern is dendritic with the tributaries joining oyun and asa river obliquely. this defines the form of the topography of the study area. the oyun and asa rivers are located on topographical low lands, while the higher elevations are located to the east and south-east. (fig. 2). the main river that drains the fig. 1 the location of study areas in kwara state, nigeria (source: kwara state bureau of lands and survey 2002) 18 agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. study area joins the asa river which finally empties its water into the niger river at jebba in niger state (kwsmi, 2002). the major land use type characterizing the oyun drainage basin is agricultural land use though some other people engage in activities like trading, commerce, administration among others (kwsmi, 2002; ahmed, 2009). the crops commonly grown include cassava, yam, melon, groundnut, sorghum, millet, pepper, tomato, and tree crops such as cocoa, kola, oil palm, mango, guava and citrus. methods randomized complete block design (rcbd) was applied with four different treatments replicated thrice. they were treatment nt (zero or no-tillage), treatment ph (plough and harrow), treatment phr (plough, harrow and ridge), and treatment t (traditional heap farming). in the study area, these are the conservative and conventional tillage types used. simulation of the tillage methods was made from the experimental plot for the entire oyun drainage basin. maize (zea mays. l. swam 1 variety) was planted for 2015 and 2016 farming years on a 5m x 5m plot size at spacing of 75 cm between rows and 50 cm within row. nitrogen, phosphorus and potassium i.e npk (15:15:15) fertilizer was applied at 4 weeks and 8 weeks after planting while a normal agronomic practice such as pre-emergence and post emergence herbicide for weed control were administered on the sets of the experimental plot (fig. 3). soil water assessment tool (swat) was used to model the pattern and process of pollution from the tillage types through an arcswat 2012.10.19 for arcgis software 10.2, 10.3 and 10.4. swat is a hydrologic model using the following components: weather, soil, land use as well as other variables to generate data on hydrologic response unit (hru). some of the features modeled in the swat environment are described in table 1. the swat was chosen because it can simulate the model with limited data and helps to describe the relationship of activities on land with the watershed hydrology. swat model involved various kinds input data for simulation of the watershed. the flow chart of the steps in the swat model application for the study area are shown in figure 4. the input data included digital elevation model (dem), and maps of land use/land cover, soil cover, and precipitation. all these data were collected, processed and converted into the swat input format. the software was run by giving these data as inputs. the various steps involved in the software are watershed delineation, hru analysis, and write input tables, edit input data and swat simulation. afterwards, the software executed the command and the output file was printed. this output file was used to plot the graphs and maps. these graphs and maps show the characteristics of watershed. fig. 3 experimental layout at utrf and ncam site to evaluate the effects of various tillage methods on soil erosion. tillage methods: t: traditional heap; p/h: plough and harrow; p/h/r: plough, harrow and ridge; nt: no tillage; r1-r3: replications fig. 2 drainage pattern and settlements in the study area (source: nigerian national space research and development agency 2017) agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. 19 results and discussion the hydrological cycle of the study area depicts the way and manner water and nutrients interact with the environment of the study area. the incoming amount of rainfall across the study area was 1230.9 mm and this number is distributed across runoff, infiltration and flow. the rate of surface runoff in this model shows a higher infiltration (distributed among the return flow, lateral flow as well as the percolation to the aquifer). the evapotranspiration rate shows a high rate of return which indicates that a deficit in precipitation would almost be certain to impact on the health of vegetation considering the rate of water loss through evapotranspiration (fig. 5). the model simulation is daily time step based. the values in table 2 are real figures for the utrf and ncam watersheds according to the input data used in the swat model. plough, harrow and ridge (phr) tillage contributed the most to the amount of surface runoff to stream flow in the main channel, surface runoff generated in hru during time step table 1 features modelled in swat parameters descriptions hydrologic response unit (hru) the hydrologic response unit (hru) is the smallest spatial unit of the model, and the standard hru definition approach lumps all similar land uses, soils, and slopes within a subbasin based upon user-defined thresholds. sub-basin a sub-basin (sub) is a structural geologic feature where a larger basin is divided into a series of smaller basins with intervening intra-basin highs. precipitation (prec) precipitation (mm) is any liquid or frozen water that forms in the atmosphere and falls back to the earth. it comes in many forms, like rain, sleet, and snow. surqgen amount of surface runoff (mm) contribution from streamflow from hru during simulation. (amount generated before transmission pothole, wetland and pond losses.) sediment yield (sed) sediment yield can be defined as the amount of sediment reaching or passing a point of interest in a given period of time, and sediment yield estimates are normally given as t/year or kg/year. surq surface runoff (mm) generated in watershed for the day, month or year soil loss soil loss (kg/ha) during the time step calculated with the usle equation (usle_ls) gwq amount of lateral flow and ground water flow contribution (mm) to main channel from hru during simulation et actual evapotranspiration (mm) in hru during simulation no3 nitrate in surface runoff and lateral flow in hru during simulation (kg n/ha) orgn organic nitrogen in surface runoff in the hru during simulation (kg n/ha) fig. 4 flow chart of the steps in the swat model to evaluate the soil erosion for the study area (adopted from akpoti 2015) 20 agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. and actual evapotranspiration generated from the utrf site with 374.42 mm, 374.42 mm and 725.78 mm respectively; while highest in plough and harrow (ph) tillage on ncam site with 284.86 mm, 284.87 mm and 698.1 mm respectively. no-till (nt) and traditional heap (t) generated the highest nitrate (5.15 and 4.42 kg/ha), organic nitrate (62.62 and 60.79 kg/ha), sediment yield (10.54 and 10.46 t/ha), soil loss (2.24 and 2.31kg/ha) and groundwater amount (174.45 and 96.32 mm) on utrf and ncam site respectively as shown in table 2 and figure 6, 7 and 8. the representation of the hydrological cycle reveals the mean values of some of features modelled for the entire study area. fig. 6 amount of surface runoff contribution from streamflow. surface runoff generated in the watershed, lateral flow and ground water flow contribution to main channel from hru during simulation, evapotranspiration in utrf and ncam sites. 0 200 400 600 800 ph nt and t phr nt and t ph phr utrf utrf utrf ncam ncam ncam s u rf a ce r u n o ff ( m m ) surq mm surqgen mm gwq mm et mm table 2 distribution of the hydrological response unit (hru) and the swat modelled parameters in utrf and ncam sub catchments tillage method name hru sub surq [mm] no3 [kg/h] orgn [kg/h] prec [mm] surqgen [mm] sed [t/ha] soil loss [kg/ha] gwq [mm] et [mm] ph utrf 44 18 372.91 4.41 50.94 1314.21 372.91 5.31 1.05 171.19 724.79 nt and t utrf 45 18 371.53 5.15 62.62 1314.21 371.53 10.54 2.24 174.45 723.6 phr utrf 46 18 374.42 3.68 29.83 1314.21 374.42 1.81 0.44 167.86 725.78 nt and t ncam 103 42 281.94 4.42 60.79 1113.86 281.94 10.46 2.31 96.32 696.6 ph ncam 104 42 284.86 3.04 27.41 1113.86 284.87 1.57 0.38 90.41 698.1 phr ncam 105 42 283.39 3.89 48.38 1113.86 283.39 4.79 1 93.29 697.47 fig. 5 flow chart of the steps in the swat model to evaluate the soil erosion for the study area (adopted from akpoti 2015) agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. 21 fig. 7 amount of nitrate and organic nitrate in surface runoff in the hru during simulation in utrf and ncam sites effect of tillage methods on runoff non-point or diffused pollutants can enter into a river or lake through various points or locations whereas contamination from point source pollutant can be linked to specific discharge points of waste water treatment plants, sewers and factories. drainage water from agricultural farm land is a major example of contamination from non-point source. the major pollutant from agricultural non-point solution (nps) that is a product of these activities are sediment, pesticides, nutrients, salts and pathogens. the national water quality inventory according to epa (2012) reported that the leading source of impairment of water quality to surveyed lakes and rivers is agricultural nonpoint source (nps) pollution, the third largest source of impairments to estuaries, and also a major contributor to the contamination of ground water as well as degradation of wetlands. physical, chemical, and biological properties of soil are influenced by tillage systems and have a major impact on the productivity of soil and water quality at a wider scope. typically, runoff water contains nutrients that are dissolved, sediment and possibly some chemicals from conventional tillage methods whereas conservation tillage decreases runoff of water, thereby increasing penetration of water into the soil. surface water quality improvement is one obvious and immediate result of conservation tillage. runoff from agricultural land may result in encouragement and excessive growth of algae and other aquatic plants, causing severe problem in water quality. algae overgrowth in particular, causes odor and taste problems for drinking water supplies and the depletion of oxygen may kill aquatic animals. sediment from cropland erosion may also increase the turbidity (cloudiness) of water, impairing fisheries (devlin and barnes (2009). this is because according to cheikh et al., (2020), suspended sediments can influence light penetration into the column of water and will likely carry nutrients and pollutants which will affect the smooth functioning of the river ecosystems. also, abebe (2019) reported that intensive agricultural practice such as tillage practices in ethiopian highlands can results in increased soil erosion rates and sedimentation in the reservoir. the result findings in this study revealed that no -till (nt) and traditional heap (t) generated the highest fig. 8 sediment yield and soil loss in surface runoff in the hru during simulation nitrate loss (5.15 and 4.42 kg/ha) which is in line with alam et al. (2014) reporting that the highest total n, p, k, and s in their available forms were recorded in zero tillage as compared to minimum tillage, conventional tillage, and deep tillage. drainage water from watershed having conventional tillage is usually brown in color and carry a lot of sediments. however, in a brazilian watershed area researcher adopted no-tillage, and found out that clear water is drained from the farmland even in times of heavy rainfall (phillips et al., 1980). turbidity and siltation levels are amplified in areas where conventional tillage practices still occur during various sampling of water quality and events of habitat assessment. the implication is that implementation of conservation tillage practices is likely to reduce fine clay particulates loading and materials from surface erosion that are delivered to adjacent waterways. therefore, perhaps the greatest water quality benefit from conservation production systems is the resulting reduction sediment loss through soil erosion and runoff (phillips et al., 1980). in this study, plough, harrow and ridge (conventional tillage) contributed more to the amount of surface runoff contribution to stream flow in the main channel, surface runoff generated in hru during time step and actual evapotranspiration generated from the utrf site with 374.42 mm, 374.42 mm and 725.78 mm respectively; while no-till and traditional heap generated the highest soil loss (2.24 and 2.31kg/ha). this is in contrast to the findings of chowaniak et al. (2020) reporting that runoff was 4.3 ± 0.6% higher under no-till than under conventional tillage, while soil loss was 66.8 ± 2.7% lower under no-till than under conventional tillage. in addition, bertol et al. (2005) reported that cu, fe, mn and ni concentrations were higher under conventional tillage than under zero tillage on topsoil and runoff. therefore, the application of tillage method can be used to achieve production, environmental and sustainable objective due to the fact that it can determine how much nutrient is available in the soil for plant growth as well as how these nutrients disintegrate into runoff and contaminate surface water. surface runoff is one of the diffused sources of the export of elements and chemical substances i n water bodies. the findings of this study showed that no-till and traditional heap generated the highest organic nitrate (62.62 and 60.79 kg/ha), soil loss 0 20 40 60 80 ph nt and t phr nt and t ph phr utrf utrf utrf ncam ncam ncam a m u n t o f n it ra te i n r u n o ff (k g /h a ) no3 kg/ha orgn kg/ha 0 2 4 6 8 10 12 ph nt and t phr nt and t ph phr utrf utrf utrf ncam ncam ncam s e d im e n t yi e ld ( t/ h a ) a n d s o il lo ss ( k g /h a ) sed (t/ha) soil loss (kg/ha) 22 agaja et al. 2021 / journal of environmental geography 14 (1–2), 15–23. (2.24 and 2.31 kg/ha) and groundwater amount (174.45 and 96.32 mm) which is in line with klimaszyk and rzymski (2011), who stated that significant loads of nitrogen, phosphorus, organic matter among others can be transported in overland flow from the catchment area to freshwater. they also reported that the quality and quantity of surface runoff depends on many factors but some of the most important factors are tillage practices and the morphology of the catchment area. as a result, surface runoff from agricultural lands is a major contributor to the eutrophication in lakes and rivers. therefore, the concentration of these parameters in overland flow can eventually contaminate fresh water sources around the catchment area. as a result, there is a need for appropriate tillage method that will contribute less to the concentration of the parameters to surface runoff. thus, conservative tillage contributed more to the features as against the opinion of it been the most suitable tillage type for attaining the best environmental conditions for sustained land resources as highlighted by several references (anthony and collins, 2006; derpsch, 2007; aina, 2011; onwuzoo, 2020). therefore, farmers must be conscious of the agricultural land management activities such that the best tillage method that is suitable for such an environment is applied to have optimum crop yield yet conserving the water quality. conclusion in conclusion, the different tillage methods had impact on water quality. the traditional heap and no -tillage methods contributed more to the surface runoff parameters than plough / harrow and plough / harrow / ridge, plough / harrow and plough / harrow / ridge contributes more to soil loss and surface runoff amount flowing to the nearest river/drainage than traditional heap and no-tillage. therefore, the study recommends that plough/harrow should be adopted for a sustainable environment due to its comparatively favorable effect on its contribution to surface runoff in this ecological zone. references abebe, t. a. 2019. calibration, validation and performance evaluation of swat model for sediment yield modelling in megech reservoir catchment, ethiopia. journal of environmental geography 12 (3–4), 21–31. doi: 10.2478/jengeo-2019-0009 adelana, s. m. a., olasehinde, p. i. 2004. assessment of aquifer system in parts of south-western nigeria using isotope techniques. proc. international workshop on the application of isotope techniques in hydrological and environmental studies, paris, september 6-8. ahaneku, i. e. 1997. comparative evaluation of some tillage systems for effective moisture conservation. in: oni, k. c. 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https://citeseerx.ist.psu.edu/%20viewdoc/download?doi=10.1.1.734.1395&rep=rep1&type=pdf https://healthwise.punchng.com/over-100000-under-five-nigerian-children-die-from-water-borne-diseases-annually-unicef/ https://healthwise.punchng.com/over-100000-under-five-nigerian-children-die-from-water-borne-diseases-annually-unicef/ https://healthwise.punchng.com/over-100000-under-five-nigerian-children-die-from-water-borne-diseases-annually-unicef/ https://www.sciencedirect.com/science/article/pii/s1658077x19300049#! https://www.sciencedirect.com/science/article/pii/s1658077x19300049#! introduction study area methods results and discussion effect of tillage methods on runoff conclusion references foreword journal of environmental geography 11 (3–4), 1–2. doi: 10.2478/jengeo-2018-0007 issn 2060-467x foreword to the special issue of the journal of environmental geography on climate change adaptation in the danube region károly gombás1, viktor györgy oroszi2* 1eu strategy for the danube region pa5 (environmental risks) hungarian priority area coordinator; north-transdanubian water directorate, árpád út 28-32, h-9021 győr, hungary 2head of division, department for water diplomacy and the danube region strategy, division for the danube region strategy, ministry of foreign affairs and trade, bem rakpart 47, h-1027 budapest, hungary *e-mail: danube.envirisks@mfa.gov.hu the danube region represents one fifth of the european union’s total area and is home to more than 100 million inhabitants. the region is comprised of 9 eu (austria, bulgaria, croatia, czech republic, germany, hungary, romania, slovakia and slovenia) and 3 accession countries (bosnia and herzegovina, montenegro, serbia) and also involves 2 neighbourhood countries (moldova and ukraine). the states show significant regional disparities in economic and social development. in order to increase growth and strengthen cooperation at a macro-regional level the european union adopted the eu strategy for the danube region (eusdr) in 2011 under the period of the hungarian eu presidency. eusdr is established with eleven priority areas to harmonise development policies connecting these 14 countries. water is one of the most important natural resources, basic elements of the human life and its quality determines the quality of our life. eusdr priority area 4 (pa4; https://www.danubewaterquality.eu/) of the eusdr aiming at to maintain and restore the quality of waters, to ‘safeguard europe’s water resources’, furthermore to assist in the implementation of the eu water framework directive (wfd) and the urban waste water treatment directive. the environmental risks priority area (pa5; https://www.danubeenvironmentalrisks.eu/) of the danube region strategy coordinated by hungary and romania has three major objectives to follow during its work in close cooperation with the international commission for the protection of the danube river (icpdr) and shares the responsibility for the realization of them. first, pa5 addresses the challenges of water scarcity and droughts based on the 2013 update of the danube basin analysis and the ongoing work in the field of climate adaptation. secondly, support to implement danube wide flood risk management plans – under the floods directive – to reduce flood risks significantly by 2021. third, it works to update the accidental risk spots’ inventory at the danube river basin level. the most significant activity in the field of environmental risks is to facilitate the flood protection of the region and to enhance the flood safety of the whole danube basin. in order to secure the long-term management possibilities, the technical education needs consolidation and a training scheme is under elaboration by the pa5. though the emphasis is on high water regime, pa5 still considers drought and ice management as equally potential scarcities. we aim to step forward in the awareness and preparedness level of the inhabitants with pilot sites for coordination of operative flood management and civil protection plans. to achieve the goals eusdr pa5 heavily support project preparations and executions, creating informational material and provide dissemination via the website, plus organizing and participating on project kick-off meetings, consultations and project development workshops, seminars. pa4 and pa5 are working closely to gain additional values. the eusdr pas are driven by a mutually accepted action plan where the countries endorsed the main topics they are collaborating on. significant policy impact and technical progress is traceable regarding climate change adaptation in pa5 action -7 “anticipate regional and local impacts of climate change through research” and action-8 “to develop spatial planning and construction activities in the context of climate change and increased threats of floods”. eusdr pa5 is intended to harmonize eu-wide, danube region and sub-regional level activities. therefore, pa5 hungarian coordination gave its opinion in december 2017 to the update of eu strategy on adaptation to climate change carried out by dg clima in order to secure feedback to the role of eu macro-regional strategies in climate change adaptation. cooperation started at the end of 2017 with the other 3 macro-regional strategies of eu on the field of risk management and climate change issues, first with a workshop in budapest (november 2017) and culminated in the jointly organized confere nce session of the eu civil protection forum 2018 in brussels (march 2018). the coordination also involved in the peer-review of the „adaptation policies and knowledge base in transnational regions in europe” etc/cca technical paper. 2 gombás and oroszi 2018 / journal of environmental geography 11 (3–4), 1–2. closer cooperation started with global water partnership cee from the second half of 2017 related to their integrated drought management programme for the better management of drought and water scarcity issues in the drb. eusdr pa5 joined to the initiation of global water partnership and carries out a common european drought and water scarcity eu level policy review in 2018. icpdr “climate change adaptation study update 2018” process was elaborated in 2017. pa5 contributed to the first review of the document and later on contributed to the preparation of the danube region climate change adaptation strategy. eu sdr pa5 hungarian coordination announced the call for paper in march 2018 of “climate change adaptation in the danube region”, as financing and launching the special issue of the journal of environmental geography thanks to the interreg danube transnational programme dtp-pac1-pa5 project (fig. 1.). thus, novel scientific results and best practices have been collected from different fields of climate change adaptation. as an important element of our task, the issue also highlights areas where transboundary cooperation is a great potential– since being the core element of the eusdr. fig. 1 project financed by european union fund (erdf) and hungary dear reader, we have seven great articles in this special issue of the journal, which are proud to hand over for the knowledge benefit for all of us. it is interesting to follow the development of the research activities in individual institutes and joint projects in the topic of climate change adaptation that is one of the most urging issues in the danube basin and the actually in the entire world nowadays. wish you a pleasant time to browse! an assessment of urban vegetation abundance in accra metropolitan area, ghana journal of environmental geography journal of environmental geography 11 (1–2), 37–44. doi: 10.2478/jengeo-2018-0005 issn: 2060-467x an assessment of urban vegetation abundance in accra metropolitan area, ghana: a geospatial approach alex barimah owusu* department of geography and resource development, university of ghana, lg 59 legon, ghana *corresponding author, email: owusuba@yahoo.com research article, received 19 february 2018, accepted 17 april 2018 abstract the essential role played by urban vegetation in making urban areas livable is often overlooked in many developing cities. this is the case of ghana where its capital, accra is developing at the expense of urban vegetation. this study was conducted at the metropolitan area of accra to estimate how the extent of vegetation cover has changed in the period of 1986-2013, using remote sensing satellite data from landsat tm and etm+. furthermore, views of key informants were assessed on changes in the livability of the city of accra which may be attributed to loss of urban green vegetation in the city. it was found that between 1986 and 2013, 42.53 km2 of vegetation was lost representing 64.6% of total vegetation in 1986. the rate of change in vegetation cover between 1986 and 1991 measured around 2.14% of the total land area annually. this however, reduced in the subsequent years measuring 0.26% between 2002 and 2008. key informants interviewed, also believe that the loss of vegetation in the city creates livability concerns relating to ecosystem functioning, temperature rise and air quality. it is therefore recommended for urban planners and decision makers to address three critical concerns of resilience, sustainability and livability, which are the missing links in the city development agenda. keywords: remote sensing, gis, spectral angle mapper, urban vegetation, resilience, sustainability introduction the role of vegetation in urban environment has become increasingly significant to planning managers and decision makers over the past few decades. this is mainly attributed to the rapid expansion of population and urban boundaries. urban vegetation is an important pointer to urban sustainability, environmental conservation and urban planning processes of a city. urban vegetation provides numerous benefits to urbanites living in these areas. it is therefore imperative to incorporate vegetation in the planning of urban landscapes. whereas the developed world has a better understanding benefits of integrating urban vegetation and open space into the urban milieu for livability sake, emerging cities of africa are rapidly expanding at the expense of urban vegetation. williams et. al (2014) wrote on the topic “our cities need more trees and water, not less, to stay livable”. they acknowledged the new awareness on the part of government agencies of australia for their quest for smarter city designs to curb boiling summers. shirazi and kazmi (2016) on the other hand wrote about the socio-environmental impacts of the loss of urban trees and vegetation in lahore, pakistan. they articulated the planning failure, which has led to loss of vegetation in the urban environment. they further reviewed public perception on loss of urban vegetation and open space and their implications for urbanites. this story is not different from other developing cities, including accra, ghana. ghana, like most developing countries, is undergoing rapid urbanization. indeed, data published by the ghana statistical service (gss, 2002; 2012) indicated that the urban population increased from 23.1% in 1960 to 44% in 2000 and then to 50.9% in 2010. it was projected that the total population of accra, the capital city will be more than doubled within the next decade (owusu, 2013). rapid urbanization is seen as an inevitable process which results from economic development and rapid population growth (rimal, 2011). this places more pressure on existing urban structures including housing and transportation. rapid urbanization, in many cases, lead to urban sprawl, which is known to convert vegetated lands to uncontrolled and unplanned residential and other urban land uses. ghana’s development drive has focused on the exploitation of their natural environment for human betterment with less consideration for the associated negative environmental impacts, particularly on green environment and opened spaces, which in turn impacts human life negatively. the net effect is the emergence of large urban centers such as accra with an economic landscape dominated by buying and selling on open streets and urban sprawl, which threatens the sustainability of the city. whiles many authors have tried to articulate the impact of ongoing urbanization on urban sprawl, waste management and land use and cover change in accra metropolitan area (ama) (owusu 2013; adaku, 2014; stow et al., 2011; appiah et al., 2014; attua and fisher, 2010), it is still unclear as to how this has 38 owusu (2018) impacted on the abundance of vegetation in the city. perhaps what will highlight the gravity of planning failure is to estimate how much vegetated areas have been converted to other uses and how much land is still under vegetation cover (vegetation abundance). this study seeks to address this gap by utilizing geographic information system (gis) and remote sensing to estimate the extent of vegetation abundance by calculating land area under vegetation in 1986, which still remains vegetated in 2013 in ama (from 1986 – 2013), and assess the implications for living in the city. the specific questions addressed in this study are: 1. how much land area of ama was under green vegetation cover in 1986? 2. as of 2013, how much land cover remains under green vegetation cover? 3. what are the implications for vegetation cover loss? the need for urban vegetation researchers have different ways of categorizing urban vegetation. some classify it as urban forest, parks and green spaces, gardens and lawns, wall or roof plants, and wetlands (guntenspergen, 2010). others identify it as roadside trees, greenbelts in streets, green areas in parks, grasslands and aquatic green spaces (huang et al., 2012). more simply, some have divided urban vegetation into three types: relict (or remnant) i.e. natural communities retained as they were before urbanization weed communities occupying new urban habitats, and artificial green spaces (ohsawa and da, 2010). another way of looking at urban vegetation is according to its three main types: natural plants, semi natural plants, and introduced plants. natural plants are those that existed before city construction. the major component of semi natural vegetation in cities is the anthropochory community (comprising companion plants). this relies closely on anthropogenic (human) interference under urban habitats and plays a special role in composing urban vegetation, mainly grasses. introduced plants can be categorized into roadside trees, urban forests, parks, gardens, street greenbelts, and so on. no matter which classification one chooses, urban vegetation plays an important role in supporting urban environment and the urban ecosystem functioning making it livable for the people. some of the key roles of urban vegetation and for that matter the need for urban vegetation are discussed below: 1. urban vegetation in carbon sequestration: carbon sequestration means capturing carbon dioxide (co 2) from the atmosphere or capturing anthropogenic (human) co2 from large-scale stationary sources like power plants before it is released to the atmosphere. once captured, the co2 gas is put into long-term storage (pacala and socolow, 2004). in photosynthesis, plants take in co2 and give off the oxygen (o2) to the atmosphere as a waste gas. the plants retain and use the carbon to live and grow. when the plant withers or dies, part of the carbon from the plant is preserved (stored) in the soil. 2. urban vegetation in air filtering: urban vegetation also increases air quality by removing and storing harmful airborne gases (dwyer et al., 2014) and by physically trapping particles, such as dust from the atmosphere (beckett et al., 2000). plants help to clean the air of pollutants, such as particulate matter. the pores of leaves remove dangerous compounds, such as nitrogen oxide, sulphur dioxide, carbon monoxide, and ozone from the air. nowak et. al., (2006) found that in the us, urban trees remove about 711,000 metric tonnes of air pollutants every year, which confers an estimated $3.8 billion of economic value. 3. urban vegetation in reducing heat: vegetation can reduce temperature or the heat island effect. the heat island effect is basically an area within the “urban environment that’s a lot warmer than the rural area surrounding it” (national geographic 2013). the excess heat is caused by impervious surface’s ability to hold and radiate heat, as well as energy created by cars, public transit, buildings and people throughout the urban landscape. increasing the amount of canopy cover would absorb heat from the environment, making it a much more comfortable and regulated climate to live in. 4. urban vegetation in recreational and beautification function: urban vegetation also provides a social value to the urban landscape. the aesthetic value of vegetation can enhance residents’ satisfaction, attachment and sense of responsibility, thereby, improving their overall well-being (groenewegen et al., 2015). urban greenery is often the host of many outdoor leisure activities for urbanites and can also provide opportunities for education and encourage physical activity. access to urban green spaces is usually free to all, which is why they promote social inclusion and provide opportunities for social interaction (swanwick et al., 2013). 5. urban vegetation in microclimate and ecosystem stability: ecologically, vegetation plays extremely important roles in reducing storm water runoff, acting as an absorbent for pollutants, microclimate regulation (harlan et al., 2006; jenerette et al., 2007) and reducing temperatures within cities. according to de groot et. al. (2002), vegetation may also retain and store water; this allows for natural drainage which reduces surface runoff and, therefore, reduces the risk of flooding in urban areas. another benefit of vegetation in an urban environment is that it provides habitat for wild life and, therefore, can help maintain and enhance biological and genetic diversity (attwell, 2000). people with better access to urban parks live longer (mitchell and popham, 2008), exercise more (bai et. al. 2013; thompson 2013), have better social cohesion (kazmierczak, 2013), and report better health generally (van dillen et al., 2012) study area this study was conducted in the ama, ghana. ama is bounded by the gulf of guinea in the south, by the university of ghana in the north, by tema township in the east and by korle lagoon in the west. figure 1 shows the map of the study area. an assessment of urban vegetation abundance in accra metropolitan area, ghana … 39 fig. 1 location of the study area – accra metropolitan area the total built-up area is about 25 km east to west and about 12 km north to south (owusu and asante, 2013). topography is generally low-lying and undulating in some areas. the higher elevation parts are about 240 meters above sea level. the rest of the area is about 60 meters above sea level. the drainage catchment area extends from the eastern boundary of the nyanyanu river catchment on the west of greater accra regional boundary to river laloi, east of tema municipal area. the ama is the most urbanized district in the greater accra region. it has an estimated population of 1,848,614 of which 887,673(48.02%) are males and 960,941(51.98%) females in 2010 (ghana statistical service, 2012). it also has the highest literacy rate of 85.1%. over 68% of the population aged 15 years or older is economically active. a lot of commercial activities are concentrated within the ama with almost all major businesses in ghana having their headquarters located there. the daily influx of people from dormitory towns makes the daytime population figures far higher than the domicile population estimate. ama lies in the coastal savannah agro-ecological zone. there are two rainy seasons. the average annual rainfall is about 730mm, which falls primarily during the two rainy seasons. the first begins in may and ends in mid-july. the second season begins in mid-august and ends in october (ama, 2013). there is little variation in temperature throughout the year. the recorded average temperature in the coolest month (august) is 24.7oc and the hottest month (march) is 28oc. due to the area's proximity to the equator, it practically experiences a uniform temperature all year round. relative humility is very high. it ranges from the daily minimum of 65% during mid-day to as high as 95% during the night. the local wind direction is predominantly west-south-west to north-north-east. wind speed normally ranges between 8-16 km/hr. there are evidence suggesting that the present vegetation found around the metropolitan area have been altered and could possibly be attributed to both climate and anthropogenic factors. much of the area is believed to have been covered by dense forest, which remnants could still be found surviving within the area (ama 2015). there is very little variation in temperature throughout the year. the mean monthly temperature ranges from 24.7°c in august (the coolest) to 28°c in march (the hottest) with annual average of 26.8°c. as the area is close to the equator, the daylight hours are practically uniform throughout the year. relative humidity is generally high varying from 65% in the mid-afternoon to 95% at night. the predominant wind direction in accra is from the wsw to nne sectors. wind speeds normally range between 8 to 16 km/hr. high wind gusts usually occur with thunderstorm activity. there is evidence to suggest the vegetation of the metropolitan area has been altered in the more recent past century by climatic and other factors. much of the metropolitan area was believed to have been covered by dense forest of which only a few remnant trees survive (ama, 2015). climate factors, combined with the topography and human activities, particularly cultivation, have imposed new vegetation structure similar to those of the southern sahel, sudan and guinea savannas north of the accra plains. the vegetation of the study area can be grouped into three (3) broad zones; comprising of the shrub land, grassland and the coastal lands. the shrub lands occur commonly around the western outskirts and the northern slopes towards aburi hills. it has dense clusters of short trees and shrubs, with an average height of around 5 meters. the grasslands are a mixture of grass species similar to those found in the undergrowths of forests. they are very short, barely exceeds 1 meter above ground. ground herbs are found on the edge of the shrub. they include species, which normally flourish after fire. the coastal zone comprises two vegetation types, wetland and dunes. the coastal wetland zone is highly productive and an important habitat for marine and terrestrial-mainly bird life. mangroves, comprising two dominant species, are found in the tidal zone of all estuaries sand lagoons. salt tolerant grass species cover substantial low-lying areas surrounding the lagoons. these grasslands have an important primary production role in providing nutrients for prawns and juvenile fish in the lagoon systems. in recent times, wetlands are however being encroached upon (ama, 2015). the dune lands have been formed by a combination of wave action and wind. they are most unstable but stretch back several hundred meters in places. there are several shrub and grassland species, which grow and play an important role in stabilizing dunes. coconuts and palms grow well in this zone, providing protection and an economic crop. most of the coconuts were planted in the 1920s but it is estimated that over 80% of those plantations have disappeared as a result of felling, disease and coastal erosion. the loss of these trees is one of the principal reasons for the severity of erosion in some areas. 40 owusu (2018) methods assessment of urban vegetation abundance and change using remote sensing there are diverse methods for assessing urban vegetation. the earliest method for urban vegetation investigation was manual statistics within a city boundary (francis, 1987). the investigation results were usually shown by a total index or distribution indices in terms of a whole city or neighbourhood of the city, respectively. obviously, this method is quite inefficient, imprecise, and time consuming. with the advancement in technology, urban vegetation can now be monitored, mapped and analyzed using remote sensing and gis techniques. some commonly used remote sensing techniques in urban vegetation analysis include normalized differenced vegetation index (ndvi), vegetation cover change detection, land cover classification (villa et al., 2012; rahman et al., 2011; li et al., 2011). satellite remote sensing is undoubtedly, one of the most effective tools for monitoring vegetation cover and change because it can guarantee the availability of extensive datasets of large spatial (up to global coverage) and temporal (back to the 1970s) coverage. landsat tm or etm+ data are the most popular satellite remote sensing data sources on an urban scale (villa et al., 2012). in a study by rahman et al. (2011), the pattern and nature of the interrelationship between urban sprawl and urban vegetation loss in dhaka, bangladesh was shown using ndvi analysis. another study by li et al. (2011) indicates vegetation change trends based on regression model by fitting simple linear regression through the time series of the integrated ndvi in the growing season for each pixel and calculating the slopes. this study used landsat tm and etm+ data and applied spectral angle mapper algorithm (table 1) to assess the urban vegetation abundance in ama. table 1 landsat satellite images used for the study satellite image acquisition date spatial resolution path/row landsat 5 thematic mapper (tm) december 1986 30 m 196/ 053 landsat 5 thematic mapper (tm) january 1991 30 m 196/ 053 landsat 7 enhance thematic mapper (etm+) december 2002 30 m 196/ 053 landsat 7 enhance thematic mapper (etm+) february 2008 30 m 196/ 053 landsat 7 enhance thematic mapper (etm+) december 2013 30 m 196/ 053 data source and preparation the images used in this study were landsat 5 thematic mapper (tm) images, and landsat 7 enhance thematic mapper (etm+) images. table 1 shows details of image data acquired for the study. the images were downloaded from united states geological survey (usgs) web page. the landsat calibration converts landsat tm, and etm+ digital numbers to spectral radiance or exoatmospheric reflectance (reflectance above the atmosphere) using published post-launch gain and offset values (landsat calibration manual) (chander et al., 2004; micijevic, 2016). the landsat standard calibration was followed. the resultant image was imported into flaash for atmospheric correction. using envi 5.3 software (itt visual information solutions, 2009); and spatially referenced before sub-setted to ama boundary. image processing and analysis the digital image processing method used in this study is classified as a supervised classification algorithm called spectral angle mapper (sam). the sam algorithm is based on the assumption that, a single pixel in an image selected represents a single ground cover material (pure pixel), and can be uniquely assigned to only one feature class (provide end member spectra). the sam algorithm is calculated based on the spectral similarity between two spectra. the spectral similarity can be obtained by considering each spectrum as a vector against the total number of bands. the sam algorithm determines the spectral similarity between two spectra by calculating (equation 1) the angle between the two spectra, treating them as vectors in a space with dimensionality equal to the number of bands (rowan and mars, 2003; kruse et al., 1993; van der meer et al., 1997). smaller angles between referenced and observed end member spectrum indicate a closer match to the referenced spectrum, whilst a wider angle indicates great difference between referenced and observed spectrum. pixels further away than the specified maximum angle threshold in radiance are not classified. this technique, when used on calibrated reflectance data, is relatively insensitive to illumination and albedo effects. equation 1 shows the calculation that the sam algorithm (kruse et al., 1993): (eq. 1) sam is a physically-based spectral classification that uses an n-d angle to match pixels to reference spectra. end member spectra used by sam can come from ascii files or spectral libraries, or one can extract them directly from an image (in-scene spectra). in this study, in-scene spectrum from pure pixel was used. this means that the inscene spectra were matched with each pixel and the sam algorithm classified each pixel based on its similarity to the end member spectrum used. figure 2 shows the workflow of the study methodology and technical approach. change mask the change mask was built in this study to show locations that were vegetated from the base year and remains vegetated at the end of the study period. it is important to an assessment of urban vegetation abundance in accra metropolitan area, ghana … 41 note that some locations change from vegetated surface to build (cleared) and change back to vegetation. in such situations all those areas were considered built hence the building of a change mask for extraction of locations that have remained vegetated from beginning till the end. the change analysis was built in arcgis environment using raster calculator tool under the spatial analyst menu. fig. 2 flow chart of workflow of data processing and analysis using the vegetation abundance image generated with sam the change was modeled by spatial analysis. first the base year image was reclassified into vegetated and nonvegetated using boolean classifier. base year was 1986 (sam1) reclassify into 1 and 0. the second year 1991 (sam2) was also reclassified into 10 and 0 vegetated and non-vegetated, the third years (sam3) also reclassified to 100 and 0, the fourth year (sam3) reclassified to 1000 and 0 and the final years (sam5) reclassified to 10000 and 0. the final change modeling was as follows: sam1+sam2+sam3+sam4+sam5 (eq. 2) the output generated were pixels with values classified as follows: 1; 0; 10; 11; 000; 100; 101; 111; 1010; 1000; 1111; 0000 etc. the position of the zero (0) indicates whether the location has changed from being vegetated at the beginning or which year it was converted from vegetation and the position of one (1) indicates when it became vegetated or has remain vegetated from the beginning (fig. 3). fig. 4 the spatial modeling for identifying pixels that remained vegetated (1986-2013) the final map for the periods were overlaid with towns and major road networks of the city which was validated with field visit to 20 selected locations. the field visit was to provide some form of accuracy assessment and we also used existing high resolution image (mainly historical) to support the validation and we found that the analysis achieved 90% accuracy. key informants’ perception on livability of the city the study sought the views of the general public on livability of the city of accra, which may relate to the loss of urban vegetation. in all, 50 key informants were contacted using snowballing method for selection within five communities. the communities include east legon, abeka, achimota, cantonments and osu. the criteria for selection include living in accra for a minimum of 35 years, being of sound mind and willingness to express your view and also being recommended by another key informant. the selection process began with a representative of the district assembly of the community (known as the assemblyman or assemblywoman), who recommends the respondent and once interview is completed, a respondent is asked to recommend the next suitable candidate. table 2 shows the composition of respondents and their communities. table 2 key informants and their respective communities of residence community male female total respondents east legon 8 2 10 abeka 6 4 10 achimota 5 5 10 cantonments 6 4 10 osu 7 3 10 although the key informant interviews were male dominated, we do not think sex composition necessarily changed the outcome of the study. structured questions relating to livability were asked in local akan language and the responses were both recorded and written down for analysis and latter interpreted qualitatively. results green areas (vegetated areas) covered about 38.01% of the total land area of ama in 1986 (fig. 4). this was reduced to 25.15% in 1991, representing 12.85% reduction in green areas. by 2002, the total green areas left were 17.18% and were subsequently reduced to 15.39 in 2008. it is important to note that the period 1991 and 2002 was 11 years instead of the regular 6 years used for all other period. this was due to unavailability of 42 owusu (2018) usable landsat images within the required interval. as of the ending year 2013, ama had only 13.45% of its total land area of 173km2 left covered with greens. figure 4, contains five images of 1986, 1991, 2002, 2008 and 2013. the images show land area covered by vegetation within and by the end of the study period. the study used change modeling to estimate areas considered as never changed. this is because there were areas that started as vegetation cover and changed to bare surface and later become vegetation again. figure 5 shows green cover statistics that represents never changed from green areas. it is important to differentiate between green cover areas and never changed areas since there are places or locations that changed several times. in 1986, 20.25% of the area was considered green areas or vegetated areas. this decreased to 13.36% in 1991 (within 6 years) and then further decreased to 6.37% by 2002, i.e. a period of 11 years. the vegetated areas further reduced to 6.20% 2008, although it seems like a very small margin over a period of 6 years. by the end of the study period of 2013, only 4.84% of the total land area remained vegetated, which are the areas that have never changed from being vegetated since 1986. fig. 5 green cover statistics of ama between 1986 and 2013: extent of green cover (%) compared to the whole study area 0 5 10 15 20 25 1986 1991 2002 2008 2013 c h a n g e (% ) fig. 4 green areas of ama for 1986, 1991, 2002, 2008 and 2013 an assessment of urban vegetation abundance in accra metropolitan area, ghana … 43 the rate at which green cover reduced in ama between 1986 and 1991 was shown in figure 6. it decreased by about 2.1% per annum and reached the peak around the year 2000. by the year 2001, the vegetation of the area had reached the lowest of the times such that roughly about 6.37% of the land was left under vegetation. between 2002 and 2008 the rate of vegetation reduction was close to negligible. it was as low as 0.2% which suggests that there were very little open green lands to be converted to other urban land uses. the rate of vegetation reduction in 2008 and 2013 shows that there was as low conversion as 0.03 which implies no conversion of any more lands. on the ground, what was observed was infillings, which are minor conversions within existing residential and commercial areas mostly by investment capitals and external forces. moreover, more vertical growth was observed as more high-rise buildings began emerging in the city center and emerging business enclaves. fig. 6 rate of green cover change (%) between 1986 and 2013 discussion and conclusion this study was conducted with the aim of assessing vegetation abundance and change from 1986 to 2013. the data analysis shows that ama has lost almost all the vegetation cover, leaving just about 4%. greater part of the vegetation loss occurred between 1986 and 2002. interestingly this period coincides with the period when ghana embarked on economic recovery program (erp) and its associated trade liberalization which many people believe was the catalyst for ghana’s urbanization and vegetation loss. this period was characterized by conversion of green spaces, including farmland into urban uses – residential and commercial. localities of green cover in ama as of 2013 include the achimota forest reserve area (a large patch of green in the northern part of the image in figure 4, 2013) and areas along water bodies in the metropolis. the study also shows that, areas such as cantonments, ridge and legon still have some vegetation although it has reduced dramatically from the base year of 1986. this large scale conversion of urban green spaces into other urban land uses, including paved surfaces have significant implications for the livability of accra, which could be best explained by its residents. the study therefore dwells strongly on the opinions expressed by the key informants on the livability of the city. the key livability concerns they expressed include the rising heat, the frequency and severity of floods and air pollution. others include concerns about the observed reduction in the rainy days, though they said they have observed increase in the intensity of rains. even though these are views expressed by some 50 residents during field data collection, it is difficult to relegate local observations to the background. this is because they live with the problem. also the livability concerns they expressed concur with views expressed in other studies from countries that have experienced similar conversion of urban vegetation (gairola and noresah, 2010; shirazi and kazmi, 2016). shirazi and kazmi (2016) wrote about the socio-environmental impacts of the loss of urban trees and vegetation in lahore, pakistan. their study reviewed public perception and the story is similar to key informant’s views from accra, ghana. this study recommends that for ama to address problems relating to loss of vegetation and city’s livability, there is the need to take a second look at the development plans implemented. there is the need for a shift in the city’s development paradigm to address what david maddox calls the city we want, which in his view must address three major challenges, including city’s resilience, sustainability and livability (maddox, 2013). whereas these three themes of city resilience, sustainability and livability have been in the past development agenda of the ama, they have been pursued individually. the past three decades saw sustainable development as the order of the decade. this shifted to building resilient cities and we are now talking of livable cities. there is the need for better understanding that sustainability can be achieved without resilience and livability, even though they may seem implicit. being a resilient city does not necessarily guarantee sustainability and livability. it is therefore important for the city of accra to think smart and look at the city’s development from these three perspectives – resilience, sustainability and livability. these will include building with the environment and living with the environment, including greens and open space management. however, ama’s biggest challenge, in achieving these recommendations including the fact that it is a resource-poor city with limited human and financial resources; lack of control 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https://doi.org/10.5721/eujrs20124529 introduction the need for urban vegetation study area methods assessment of urban vegetation abundance and change using remote sensing data source and preparation image processing and analysis change mask key informants’ perception on livability of the city results discussion and conclusion references investigating the drivers of total suspended journal of environmental geography 13 (1–2), 31–42. doi: 10.2478/jengeo-2020-0004 issn 2060-467x investigating the drivers of total suspended sediment regime in the senegal river basin using landsat 8 satellite images cheikh faye1*, manuela grippa2, laurent kergoat2, elodie robert3 1department of geography, u.f.r. sciences and technologies, uasz, laboratoire de géomatique et d'environnement, bp 523 ziguinchor, senegal 2geosciences environnement toulouse, university of toulouse iii, route de narbonne, 31330 toulouse, france 3cnrs, university of nantes, umr letg, campus du tertre bp 81227, 44312 nantes cedex 3, france *corresponding author, e-mail: cheikh.faye@univ-zig.sn research article, received 25 february 2020, accepted 27 april 2020 abstract because total suspended sediments (tss) influence the penetration of light into the water column and are likely to carry pollutants and nutrients, their study is essential for understanding the functioning of african river ecosystems. if the estimation of solid transport is important in the context of hydro-agricultural developments, its quantification often poses a problem. in addition, in situ data for these areas are rare and, as a result, the environmental factors responsible for the variability of tss can hardly be understood. this work aims to evaluate the spatiotemporal variability of tss in the surface waters of the senegal river using satellite data over the 20142018 period. the spatio-temporal dynamics of tss is reconstructed using a relationship established on several west african sites between in situ data from tss and satellite reflectances from landsat 8. these data allow analyzing the relationship between tss and factors such as rainfall and discharge. we found that the tss peaks in bakel coincide with the arrival of the first rains and are followed by peaks in discharge with a lag of 2 months. a time lag between tss and discharge peaks is also observed on its tributaries like the river falémé. concerning the spatial variability, tss generally increase from the river upstream to the downstream and decrease in the senegal delta after the diama dam. the analysis of the tss upstream and downstream of the manantali dam, in the upstream area, confirms the relatively low sediment deposits in the dam lake. keywords: water color, suspended particulate matter, landsat image, remote sensing, senegal river introduction in the context of climate change, a recent trend in increasing daily precipitation extremes has been detected in tropical africa (panthou et al., 2014; taylor et al., 2017). increased runoff and erosion, as well as increased precipitation, suggest a possible increase in turbidity and suspended sediments (ss) in rivers. beyond their importance to hydrology, sediments also have an impact on inland water ecology and potentially on human health. indeed, tss by forming a refuge and a culture medium conducive to the growth of bacteria generally promote their development while reducing their mortality by protecting them from ultraviolet rays (palmatee et al., 1993). thus, in environments with high turbidity, fecal bacteria have high attachment rates to particles (rochelle-newall et al., 2015). in addition, troussellier et al. (2004) noted good bacterial survival after a long residence time in the water (4-5 days) of the senegal river. some of these bacteria or viruses cause widespread diseases, such as diarrhoea, which is one of the leading causes of death among children under five in developing countries (troeger et al., 2017). due to the scarcity of in situ monitoring in the sahel, the development of methods for monitoring turbidity and suspended solids in the senegal river catchment area is therefore essential. indeed, the distribution and dynamics of tss in the senegal river catchment area (tss level, seasonal cycles and interannual variability) are not always well known. however, the study of water colour by remote sensing can be used to monitor water turbidity and tss. indeed, suspended particles absorb and scatter light affecting the spectral response of surface waters, particularly in the visible and near infrared (nir), which varies according to concentration, mineralogical composition, organic content and particle size distribution (reynolds et al. 2010). although the use of remote sensing in sub-saharan africa is confronted with specificities such as high aerosol content, very high turbidity and tss values, recent studies have shown that satellite data are effective in monitoring the variability of turbidity and tss in continental waters in these regions. kaba et al. (2014) studied the temporal dynamics of an ethiopian lake using landsat images. robert et al. (2016, 2017) used modis and landsat data to document tss and turbidity in the bagré reservoir in burkina faso (robert et al., 2016), and in the gourma region of mali (robert et al., 2017). many sensors have been developed for various water color applications, including water turbidity assessments, sensors such as avhrr, seawifs, modis, ikonos, landsat tm and etm +. variations in temporal and spectral resolutions, data availability, calibration issues and temporal coverage are some of the most important factors determining the selection of the best instrument for a particular study (li and li, 2004). although the 32 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. application of water color algorithms to estimate water constituents is generally limited by site-specific factors (hellweger et al., 2004), and the absence of a uniform model of remote sensing to estimate the tss (wang et al., 2004), satellite images can be effectively employed to recover water quality parameters. in this context, the objectives of this article are as follows: (i) analyse the seasonal cycle and interannual variability of tss in the senegal river basin using landsat images; (ii) study the links between tss variability and precipitation and discharges; (iii) explore the variability of tss in the senegal river basin, including the manantali dam and major tributaries. study area the senegal river, some 1700 km long, drains a 300,000 km2 basin straddling four countries: guinea, mali, senegal and mauritania (fig. 1). it ranges from 10°20' to 17° n and 7° to 12°20' w and is made up of several tributaries, the main ones being the bafing, bakoye and falémé rivers that originate in guinea and form the upper basin (omvs, 2008) (fig. 1). the senegal river, formed by the junction between the bafing and bakoye rivers, receives the kolimbiné and karokoro rivers on the right and falémé on the left, 50 km upstream from bakel. in the southern part of the basin, the density of the surface drainage system reflects the impermeable nature of the land (rochette, 1974). the basin is generally divided into three entities: the upper basin, the valley and the delta, which differ greatly in their topographical and climatological conditions. the upper basin extends from the s ources of the river (fouta djalon) to the confluence of the senegal river and the falémé river (downstream of kayes and upstream of bakel). it is mainly composed of the guinean and malian parts of the river basin and provides almost all of the water inputs (more than 80% of the inputs) of the river to bakel (omvs, 2008). the analysis of the hydrological system of the senegal river basin reveals four hierarchical levels: (1) the natural (uncontrolled) reaches of the bafing upstream of the dam (falémé and bakoye), (2) the reach of the bafing downstream of the dam (controlled), (3) the reach after the confluence of the bafing and the bakoye (at kayes), (4) the reach after the confluence of the falémé and the semi-artificialized bafing-bakoye subsystem (at bakel). from a hydrological point of view, at bakel, which is often considered the reference station of the senegal river, the average annual discharge of the river is about 676 m3/s, corresponding to an annual input of about 21 billion cubic metres. mean monthly discharges range from extreme values of 3,320 m3 /s in september to 9 m3/s in may (ndiaye, 2003). for the distribution of hydrological inputs from the main rivers in the basin, 50% come from the bafing (which is the main tributary), 25% from the falémé, 20% fig. 1 location of the senegal river basin and sites for estimating tss. 1: senegal river site in saint louis ; 2: senegal river site in podor ; 3: senegal river site in matam ; 4: senegal river site after faleme ; 5:faleme river site in kidira ; 6: senegal river site before faleme ; 7: senegal river site after bakoye ; 8: bakoye river site in oualia ; 9: senegal river site before bakoye ; 10: bafing site after manantali ; 11: site downstream of the manantali dam : 12: site upstream of the manantali dam ; 13: bafing site before manantali faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 33 from the bakoye and the remaining 5% transit from the other tributaries of the senegal river (omvs, 2012). various studies in this basin have highlighted climate change and changes in its hydrological regime since the 1970s (faye et al., 2015; wilcox et al., 2018). indeed, faced with a very strong drop in precipitation, which installed the senegal river basin in a succession of deficit years. the average discharge module at bakel thus decreased by more than half and went from 1374 m3/s over the period 1903-1950 to 597 m3/s over the period 1951-2002; and from an average of 840 m3 / s over the period 1950-1972 to only 419 m3/s over the period 1973 (omvs, 2012). the width of the senegal river is variable, it is on average 450 m, a width which decreases to reach 400 m only between guinea and mali. at the level of the bakoye, the average width is 250 m. at the level of the valley, the river surrounds a large arm 600 m wide, 12 m deep and a small arm 200 m wide at saint-louis. faced with the effects of climate change and changes in the hydrological regime, a series of developments (diama and manantali dams) were initiated, totally transforming the hydrological dynamics of the senegal river basin. the diama dam, located on the senegal river 27 km upstream of saint-louis, was put in water in 1986. besides its function of blocking the ascent of salt water, it ensures the availability of fresh water while throughout the year for all uses, the development of an irrigable potential of 120,000 ha, the improvement of the filling of lakes (guiers in senegal, rkiz in mauritania). the manantali dam, built between 1982 and 1988, is located on the bafing river, the main tributary of the senegal river, 90 km upstream of bafoulabé. at the filling level of 208 meters ign, its reservoir has a capacity of 11.3 billion m3 and covers an area of 477 km². the manantali dam regulates the flow of the senegal river and irrigates a potential of 255,000 ha of land and, in the long term, should make it possible to navigate the river for approximately 800 km from its mouth (omvs, 2012; faye, 2018). the manantali dam was built to guarantee a maximum flow of less than 4,500 m3/s at bakel (thiam, 2016), causing sediment retention at the level of sn lake. data and methods satellite data for this study, we used the surface reflectances of the landsat 8 oli satellite available since 2013 . these data, corrected by atmospheric effects, are provided by the united states geological survey. they were analyzed from google earth engine (and partially downloaded from earth explorer). landsat 8 has several spectral bands in the visible, near infrared and mid-infrared, with a spatial resolution of 30 m and acquires the data with a temporal repetitiveness of 16 days. for this work, we used the blue, green and red bands (2, 3 and 4 at 482 nm, 561.5 nm and 654.5 nm respectively), the near infrared band (5 to 865 nm) and the swir bands (6 and 7 at 1613.5 nm and 2202 nm). data were extracted from 13 sites located along the senegal river (fig. 1). landsat 8 was chosen for this study because it allows monitoring small rivers such as the tributaries of the senegal river (spatial resolution of 30 m) using consistent time series since 2014. modis satellite data were not retained because their spatial resolution (250 m) does not allow monitoring the dynamics of tss in small rivers. sentinel-2 data could provide complementary information to landsat data, and work in ongoing to evaluate their potential to retrieve tss over west africa, and particularly the effect of sunlight, that given the smaller angle of the image acquisition could be more important than for landsat. moreover, the first sentinel-2 images date back to december 2015 and over the study area, at the time of this study, full times series of level 2 products (atmospheric corrected images) were not yet provided. cloud images and images with high aerosol levels over the study sites were discarded based on the quality indices provided with the landsat satellite data (clouds, adjacent clouds, cloud shadows, aerosols, cirrus clouds). tss were estimated only for open water pixels. pixels that were not already masked by clouds, aerosols or cloud shadows were classified as open water using a threshold on the mndwi index (robert et al. (2017). for this study area a threshold of 0.1 was applied. rainfall and discharge data rainfall and daily discharge data are also used in this study. the rainfall data come from the database of the national civil aviation and meteorology agency. these are daily rainfall data from the stations of kédougou, podor, matam and saint louis from 2014 to 2018. hydrological data are daily discharges from the stations of bakel on the senegal river and kidira on the falémé river from 2014 to 2018. these data come from the database of the organization for the development of the senegal river. estimation of tss tss measurements acquired at different sites in west africa were used to evaluate different satellite indices proposed in the literature, which use visible and infrared bands. only images acquired within three days of the in situ sampling dates were selected for this analysis. a total of 49 images were used for this study. for the comparison of in situ data and satellite reflectances, the open water pixel closest to the coordinates of the in situ sampling points was chosen to approach as closely as possible the in-situ sampling point. the in situ water samples used for the estimation of the tss were collected over the period december 2014 – september 2017 in the bagré reservoir (burkina faso) (robert et al., 2016), in lake agoufou (gourma region in mali) (robert et al., 2017) and from mid-2015 to early 2016 in the niger river in niamey (kennedy bridge). these sites cover the different types of surface water (lakes, reservoirs and rivers) found in west africa. at each site, measurements were performed every week during the rainy season and every 15 days during the dry season. for the bagré site, a field mission was also carried out in july 2015 to study the spatial variability within the lake. in total, 52 in-situ measurements were used for this study: 21 for the bagre lake, 25 for the agoufou lake and 6 for the niger river. 34 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. for all these sites, the tss concentration was calculated by filtering the water samples using 0.7 µm glass fibre filters. before filtration the filters were dried for 1 hour at 105° c and weighed. after filtration, the filters were dried again under the same conditions and weighed. the tss concentration was calculated as the difference between the weight after and before filtering, divided by the filtered volume. for each sample, two replicas were used and the average tss value was used for the analysis. correlations were evaluated using the r2 (coefficient of determination, equivalent to the pearson’s correlation), with the r software. results relationship between satellite reflectance and tss landsat 8 reflectance for different combination of visible and near-infrared bands proposed in the literature were plotted towards in-situ tss and fitted using power relationships (robert et al., 2016, 2017). then, the tss retrieved from landsat 8 using the relationships obtained for each band combination were compared to in-situ tss (table 1). table 1 value of r2, rmse and bias obtained by linear regression of retrieved tss towards in-situ tss bands or ratio of bands r² rmse bias nir 0.91 389.2 -27.9 r 0.53 925.1 -71.6 nir + r 0.86 492.3 -15.5 nir/r 0.76 1562.8 -608.7 nir/b 0.81 939.7 -262.3 (r-nir)+(r+nir) 0.69 2715.8 -1063.2 the best results are obtained for the nir band (table 1) with the following power relationship (fig. 2): 𝑅𝑒𝑓𝑙_𝑏𝑎𝑛𝑑𝑒5 = 256.46 × 𝑇𝑆𝑆 ^ (0.3539), where refl_bande5 is the mean reference value of band 5 of the landsat image. tss are then estimated by the following equation: 𝑇𝑆𝑆 = 𝑅𝑒𝑓𝑙_𝑏𝑎𝑛𝑑𝑒5/ 256.46 ^ 1/ 0.3539 tss retrieved from landsat 8 are well correlated to in-situ tss (r2 = 0.91), with a very low bias (-27.9) and rmse equal to 389.2 mg/l (fig. 2b). tss in the senegal river basin were therefore estimated by reversing this power relationship, which is assumed to be generally applicable to surface waters up to values of about 2500 mg/l. variation of tss in the upper basin as a function of rainfall and discharge data daily data we compared the tss, calculated from landsat 8 satellite data, at the outlet of the upper senegal river basin with rainfall data from the kédougou station and hydrological data from the bakel station (fig. 3). the seasonal rainfall pattern shows very heavy rainfall in the rainy season, which can reach more than 100 mm per day with a maximum recorded during the month of august. total rains are close to zero during the dry season months (fig. 3). the same is true for discharge in the basin charcaterised by two periods: the high water period centred on the months of july, august, september and october with a maximum in september; the low water period is centred on the rest of the year, with the lowest discharges of the year (fig. 3) due to the absence of rain. local precipitation is combined with water inflows from the river upstream of bakel and its tributaries. the enrichment in suspended solids during the rainy season is due, particularly in the upstream part of the basin, to the strong erosion of the slopes which leads to leaching and particle loading into the river (mbaye et al., 2016). surface runoff in the region of a) b) fig. 2 relations: a) landsat reflectance in band 5 versus tss measured in situ (in mg/l), b) tss derived from landsat 8 vs. in-situ tss (n=52). r² indicate the pearson’s correlation. rmse the root mean square difference, bias the mean difference. the 1:1 line is also indicated in black faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 35 these soft sediments have a suspended matter concentration of ∼1 g/l and is responsible for 50–80% of the riverine suspended load via slope erosion. in the river bed, this suspended load is diluted by subsurface and groundwater discharge (kattan et al., 1987). during the dry season, the river becomes very "calm", while its turbidity and discharge remain low. during the 2013-14 flood period, the main inputs recorded in bakel came from unregulated tributaries (falémé: 39.6% and oualia: 26.8%), with manantali providing only 10.5% of the 42.2% it received from bafing upstream. on the other hand, during the low water period of the same year, the regularized tributary of the bafing river provides almost all the discharge at bakel, through the support of the low discharge of the dam. similarly, discharge at falémé and bakoye rivers (2.69% and 1.15% respectively) contribute very little to the discharge at bakel in senegal river. this reverse operation allows the control of large discharge during the flood period (i.e. an average discharge released of 197 m3/s) while during the low water period, the gates of the manantali structure are more open for water releases (i.e. an average discharge released of 262 m3/s). figure 3 shows that the tss concentration generally increases with the arrival of the first rains and before the increase in the river discharge. however, the tss experiences significant variations with the highest values between may and september, and which sometimes approach 1000 g / m3 (820 g / m3 on july 11, 2014). at this station, while most of the peaks occurred between july (beginning of the rainy season) and august (820 g/m3 in 2014-15, 342 g/m3 in 201415 and 400 g/m3 in 2017-18 in july and 508 g/m3 in 2016-17 in august), some peaks of suspended solids are recorded in september (this is the case on 13 september 2014 with 214 g/m3), when river discharge is highest and at the time of annual precipitation maxima. a secondary peak, which is not explained by hydrological variations (rain or discharge), is observed in march 2015. the concentration of tss at the outlet of the falémé basin was estimated between 2014 and 2018 and compared to the discharge at kidira station (fig.4). for the year 2014, the results remain fairly similar to those noted at the outlet of the upper senegal river basin, with always the peaks of tss preceding the peaks in discharge. for the other years, tss data at the beginning of the rainy season, when cloud cover prevents visibility and therefore detection with optical images, are not in sufficient number to establish a relationship. monthly averages on a monthly basis, the average tss concentration values over the period 2014-2018 indicate a unimodal evolution (in the form of a bell) with a maximum in july with 590 g/m3 and a minimum in february with 21.1 g/m3 in bakel (fig. 5). this behaviour alternates between july and august over the different years of the series with a maximum noted in july with 554 g/m3 in 2014-15, 343 g/m3 in 2015-16 399 g/m3 in 2017-18 and in august with 226 g/m3 in 2016-17. for the monthly minimum of tss, the value can be very low, falling to 0.09 g/m3 in january over the 2014-2018 period. over the period 2014-2018, the kidira station on the falémé river shows a maximum in august with 351 g/m3 and a minimum in december (6.42 g/m3) (fig. 5 and table 2). fig. 3 relationship between the daily rainfall (kédougou station), daily concentration of tss (downstream of bakel) and the daily discharge at the outlet of the upper senegal river basin (bakel station) from 2014 to 2018 36 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. the comparison between the discharge and the tss concentration clearly shows the difference between the two peaks at bakel and kidira (fig. 5). in bakel, while the peak of tss is recorded in july with 590 g/m3 (when the discharge was only 524 m3/s), the peak of discharge is recorded two months later, in september with a value of 2428 m3/s (when the tss was only 128 g/m3). for the kidira station on the falémé, this same lag persists with a peak discharge noted in september (with a discharge of 990 m3/s corresponding to a discharge of 263 g/m3 for tss), one month after that of the tss with a value of 351 g/m3 in august (when the discharge was 707 m3/s). evolution of tss in the valley and delta of the river beyond the upper basin, which covers 56% of the basin's surface area and extends from the source to the bakel hydrological station over a distance of 980 km, the tss are assessed in the valley, which covers 35% of the basin's surface area and extends over 600 km, and the delta, which extends from richard-toll to the mouth of the river over 170 km (thiam, 2016). to characterize the tss in the senegal river valley and delta, the stations of matam and podor (for the valley) and saint louis (delta) were selected. figures 6 and 7 show that the concentration of tss generally begins to increase with the arrival of the first rains, before the river's discharge increases, and tss peaks mainly in late july (727 g/m3 in matam and 531 g/m3 in podor) and august (344 g/m3 in saint louis), often slightly later (fig. 7) than for some sites previously studied in the upper basin (bakel for example). at the same time, in the valley and delta of the basin, rain peaks are recorded, as are tss, in august (137 mm in matam, 92.1 mm in podor and fig. 4 relationship between the daily concentration of suspended solids at the outlet of the falémé basin (upstream of bakel) and the discharge (kidira station) from 2014 to 2018 fig. 5 relationship between the monthly concentration of suspended solids and the monthly discharge at the outlet of the upper senegal river basin and at the confluence with the falémé from 2014 to 2018 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 37 81.2 mm in saint louis), one month before those of discharge that are recorded in september (502 cm in matam, 350 cm in podor and 102 mm in saint louis). although the tss show significant variations with the highest values between july and september and a gradual evolution from upstream to downstream, they are, on the other hand, more important in the rive r valley (the maximum being 811 g/m3 on 29 july 2018 in matam and 818 g/m3 on 25 july 2014 in podor) than in the delta (where the maximum is only 666 g/m3 on 12 august 2018 in saint louis). the lowest tss values are recorded during the low water period. in the valley and the delta which is in the alluvial plain of the basin, it is the heights of water which are available and indicated in place of the discharge as in the other parts of the basin. indeed, the tss values in saint louis are much lower than those observed in podor (fig. 7 low), despite a fairly similar rainfall dynamic (fig. 7 high). this is in agreement with kane (1997) who estimated a solid transport of the senegal river, although highly variable from one year to another, relatively low during these hydrological cycles, with an average value of 2 million tonnes/year. this may be due to the diama dam, whose commissioning in 1985 introduced a reduction in solid inputs, and modify the hydrological regime towards the lower estuary, also affecting the sediment balance that contributes to the maintenance of coastal areas and the coast south of the mouth of the senegal river (kane, 2005). thus, the tss that pass through from the diama dam are essentially made of fine materials, indicating a river of low competence in its estuary, with clays and silts transported in suspension tending to settle upstream of the dam (kane, 1997). table 2 monthly average values of suspended matter concentration in the senegal river and discharge (at the outlet of the upper senegal river basin) from 2014 to 2018 tss and discharges m j j a s o n d j f m a yrs discharge at bakel 76 143 524 1643 2428 1166 441 226 150 114 97.9 83.1 591 tss at bakel 14.1 590 316 128 97.0 24.2 35.1 21.6 21.1 20.3 127 discharge at kidira 0.60 10.2 208 707 990 346 98.8 45.0 23.1 4.04 1.80 0.58 203 tss falémé at kidra 21.8 98.3 351 263 65.7 20.1 6.42 34.7 7.54 96.5 tss per section m j j a s o n d j f m a yrs tss senegal in saint louis 21.8 116 344 181 67.0 27.4 13.3 9.4 9.2 14.7 10.4 74.0 tss senegal in podor 47.3 531 457 346 167 95.0 83.5 26.8 14.7 40.1 71.1 171 tss senegal in matam 40.8 727 290 132 176 24.8 22.0 27.3 26.6 28.5 22.9 138 tss bakoye in oualia 203 108 177 262 135 59.0 25.2 49.5 26.4 16.0 106 tss senegal after confluence with the bakoye 4.8 29.6 120 122 29.3 12.9 6.2 8.6 3.4 2.0 5.4 31.3 tss senegal before confluence with the bakoye 4.0 28.1 47.1 95.7 39.4 10.3 3.4 5.8 4.1 2.0 2.4 22.0 tss senegal after confluence with falémé 143 298 168 108 34.0 10.7 6.57 18.0 98.3 tss senegal before confluence with falémé 47.7 177 239 63.0 7.15 14.7 3.71 4.80 69.6 senegal downstream manantali 3.0 32.2 36.3 0.2 53.6 15.4 13.6 3.4 0.6 1.0 15.9 senegal upstream manantali 21.3 12.4 36.5 52.8 17.2 5.9 4.3 2.9 1.7 1.0 15.6 fig. 6 daily evolution of the concentration of suspended solids from the senegal river in the valley (matam and podor) and the delta (saint louis) 38 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. the seasonal variability of the concentration of suspended solids in the senegal river valley and delta shows a peak at the beginning of the rainy season in matam and podor that precedes the peak precipitation by one month and the peak water level by two months (fig. 7). this is in line with the tss -rain-discharge relationships observed at the bakel station. in saint louis, after the diama dam, the peak of tss is observed in august. impacts of tributaries on water and sediment supply in the senegal river to characterize the impacts of tributaries on the water and sediment supply of the senegal river, we characterized the tss of the senegal river on its upstream and downstream section and each of its tributaries: first on the senegal river upstream and downstream of the manantali dam; then on the senegal river upstream and downstream of the confluence with the falémé river; finally on the senegal river upstream and downstream of the confluence with the bakoye) (fig. 8). on the section of the senegal river before the confluence with falémé, the peak of tss is noted later (in september with 239 g/m3) compared to the part after the confluence with falémé (whose peak is noted in august with 298 g/m3) (fig. 8). with the exception of september, the concentration of ss on the part after confluence with the falémé is higher than that of the part before confluence of the senegal river with the falémé. on an annual scale, because the concentration of tss is higher in the falémé (with 128 g/m3) than in the senegal river upstream of kidira (47.1 g/m3), it is higher in the downstream part confluence between the falémé and the senegal river (with 119 g/m3) than in the upstream part (table 3). in general, discharge at bakel station are much higher than those measured at kidira (fig. 8). according to omvs (2012), the annual modules of the main rivers in the basin are as follows: 180 m3 /s at manantali on the bafing; 149 m3 /s at oualia on the bakoye; 134 m3 /s at gourbassi on the falémé; 676 m3 /s at bakel on the senegal river. a tributary such as the falémé, whose discharge remains natural, has a slightly higher concentration of suspended solids than the senegal river upstream of kidira, a fact that could be explained by the role of the manantali dam in retaining sediments in its lake and thus reducing sediments in the downstream part of the dam. thus, although falémé is more heavily loaded with suspended solids, its sediment supply to the senegal river is mainly marked by its relatively smaller volume of water than that of the senegal river (falémé representing only 25% of the discharge flowing into bakel. by comparing the tss of the different tributaries of the senegal river (bafing, bakoye and falémé), through a characterization of the tss of the senegal river on its upstream and downstream section and of each of the tributaries, we can generally observe an increase in the concentration of tss after the confluence of the tributaries (table 2 and 3). if we take the section of the confluence with the bakoye basin, the average concentration of tss over the period studied before the confluence, which is 18.1 g/m3, increased slightly to 19.4 g/m3 after the confluence, an increase of 1.3 g/m3 (at a rate of 7.2%), indicating a slight excess of the tss concentration in the bakoye over the senegal river. similarly, for the section of the confluence with the falémé basin, the average concentration of tss over the period studied before the confluence, which is 69.6 g/m3, increased to 98.3 g/m3 after the confluence, an increase of fig. 7 monthly evolution of tss concentration, rainfall and water levels in the valley (matam and podor) and delta (saint louis) of the senegal river faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 39 fig. 8 daily and monthly evolution of the senegal river tss concentration (upstream and downstream of the confluence with falémé) from 2014 to 2018 table 3 evolution of the annual concentration of tss (in g/m3) of the senegal river from upstream to downstream in the basin valley and delta 2014-15 2015-16 2016-17 2017-18 average senegal in saint louis 82.3 65 88.2 104.2 84.9 senegal in podor 168.8 144.8 181.8 130.8 156.6 senegal in matam 130.7 99 123 142.6 123.8 senegal in bakel 237 74 98.1 115 131 falémé in kidira 169 98 78.6 167 128 bakoye in oualia 90.7 90.6 99.9 71.3 88.1 senegal falémé 2014-15 2015-16 2016-17 2017-18 average senegal downstream of falémé 102 123 70.3 169 119 senegal upstream of falémé 68.2 49.0 66.5 57.7 47.1 senegal bakoye 2014-15 2015-16 2016-17 2017-18 average senegal downstream of bakoye 23.0 28.3 10.5 16 19.4 senegal upstream of bakoye 33.0 13.9 16.3 9.3 18.1 senegal manantali 2014-15 2015-16 2016-17 2017-18 average bafing downstream of manantali 19.9 48.3 60.6 35.3 41.0 bafing downstream of manantali 21.4 21.1 49.6 53.3 36.4 section at the entrance of the manantali dam 13.9 6.9 13.7 16.5 15.6 section at the exit of manantali 21.4 39.9 16.1 18.0 15.9 40 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 28.6 g/m3 (with a rate of 41.1%), also indicating a very high sediment supply from the falémé to the senegal river. in the bafing basin, the concentration on both sides of manantali remains lower in the upstream part (36.4 g/m3) than in the downstream part (41.0 g/m3). in the valley, the transverse gradient, marked by an increase in tss from upstream to downstream, remains strong (123.8 g/m3 in matam; 156.6 g/m3 in podor), while in the delta, with the presence of marine dynamics and the sediment retention role of the diama dam (kane, 2005), the concentration of tss is declining (84.9 g/m3 in saint louis). figure 9 shows the monthly evolution of the concentration of suspended solids along the senegal river. it appears that, in general, the concentration of tss increases, in relation to the increase in the volume of water flowing, from upstream (the source) to downstream (valley area), even if the seasonal distribution is not the same. impacts of the manantali dam on sediment deposition in the senegal river the comparison of the upstream and downstream tss concentration curves shows a more or less similar evolution over some periods, and different over others (fig. 10). however, analysis of tss values in the upstream part of manantali indicates the relatively low sediment supply of bafing in the lake of the manantali dam (the annual average of the series being 13.3 g/m3). this indicates a relatively limited accumulation of ss in the lake of the manantali dam. if we compare the average concentration of tss in the upstream part (with 13.0 g/m3) with those in the downstream part (with 20.1 g/m3), the average concentration of tss in the downstream part of the dam is sligthly higher than that in the upstream part of the dam (with a difference of 7.1 g/m3). only for 4 dates the average concentration of tss in the upstream part is higher than in the downstream part indicating a potential sediment deposition in the dam lake. overall the potential sediment deposition is relatively low. however, some peaks can occur upstream and are accompanied by significant retention. this is why, the potential weak sediment deposits in the lake of the manantali dam (noted over certain periods where the tss upstream are higher than those downstream) do not allow us to affirm the absence of excessive sedimentation. this is why, the manantali dam is for the moment spared from excessive sedimentation which constitutes one of the major problems associated with dams (this sedimentation can block the valves of a dam and cause its failure under certain conditions) (zhang, 2014). fig. 9 monthly evolution of the senegal river tss concentration from upstream to downstream in the basin fig. 10 relationship between the concentration of tss on the bafing section (upstream and downstream of the manantali dam) from 2014 to 2018 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. 41 discussion the use of the nir band of landsat 8 images has proven to be very appropriate for turbidity monitoring in a river characterized by high turbidity values and high spatial and temporal variability. these same landsat satellite data were selected by robert et al. (2017) to document tss and turbidity in the gouma region of mali. our study confirms the potential of sensors and the infrared band for monitoring the dynamics of tss in west african surface waters. the surface reflectances of landsat 8 made it possible to analyse the spatial and temporal variability of turbidity in the senegal river basin over the period 20142018. in terms of seasonal cycle, the increase in tss concentration is mainly caused by rainfall between the early rainy season and the mid-rainy season. the concentration of tss therefore generally increases with the arrival of the first rains before the river's discharge increases. however, this does not concern the whole basin (but only the upper basin), because there is sometimes a temporal difference between the upstream (upper basin) and downstream (valley and delta) zone of the basin. in semi-arid environments, runoff induced by the first rains could lead to increased transport because the soil surface has very low vegetation cover (mbaye et al., 2016). later in the season, with the development of vegetation in cropland and pasture, erosion and sediment transport are reduced, as well as the concentration of tss in rivers and lakes or reservoirs (robert et al., 2016). at the stations in the upper part of the basin, most of the peaks occurred between july and september (high water period), often before the annual peaks in precipitation and river discharge (as in the lower part of the basin where peaks are noted in late july and early august). these results confirm those of mbaye et al. (2016) which indicate a concentration of tss measured at a station in july 2012 (dembancane; between bakel and mattam) of 540 mg/l, well above the concentrations observed in august 2013. they are also in agreement with the tss concentrations presented in kattan et al. (1987), which found maximums during the first rainy season in june/july before the peak discharge from august to october. our work also confirms the results of kane (2005) who notes a rapid increase in tss with the arrival of annual flood waters that carry sediment from watershed erosion. at the interannual scale (over the period 20142018), a large variability in the concentration of tss was observed in the basin on all sections. although there are significant variations in tss, they are higher in the river valley than in the delta and upper basin. these results are consistent with those reported by mbaye et al. (2016) which indicate much higher tss concentrations during the rainy season with values between 5.4 and 366.4 mg/l, with a general increase in tss at downstream stations and a slight reduction at estuarine stations. they are also in agreement with those of kane (2005) who, based on the tss measurements made, noted a rapid increase in tss with the arrival of annual flood waters that carry sediment from watershed erosion. his study showed that concentrations remain relatively high (almost 200 mg/l) until the end of september beginning of october, after which time solid loads decrease very rapidly. according to his study, hydrological cycles show that on a monthly scale, the months of august, september and october account for almost all (95%) of the solid load. it is worth noting the drastic decrease in tonnage from november onwards (around 2% and even less) and the insignificant percentages in december (less than 1%). according to zhang (2014), excessive sedimentation is one of the major problems identified and associated with dams and can block its doors, causing the dam to rupture under certain conditions). fortunately, in the manantali dam, small peaks of tss are noted, peaks which can hardly cause the silting up of the dam. finally, satellite estimates were also used to assess the dynamics of tss in the manantali dam. the comparison between an upstream and a downstream site shows first of all the low sediment supply from the upstream section and the relatively low impact of the manantali dam on sediment retention in its lake. these results therefore confirm the estimates that have been made, which revealed that the senegal river has brought small proportions of silt into this reservoir on average per year. they are also in line with the observations of sogem (société de gestion de l'energie de manantali) officials who confirm that the current siltation rate in the manantali reservoir is negligible, which is consistent with the extreme clarity of the water in the reservoir (faye, 2018). an impact study estimated that 530,000 tonnes of suspended solids, 50% of which were particles less than 0.002 millimetres in diameter, were added to the reservoir each year, estimating a lifespan of 450 years (estimated period of filling in the dead water volume of the reservoir by sedimentary deposits observed at the time) (faye, 2018). however, tss peaks may occur, as noted in this study, and lead to a significant potential sediment deposition. in addition, over an extended period of time, sediment will continue to accumulate behind the walls of the dam. conclusion landsat 8 satellite data provided valuable information on the spatial and temporal variability of suspended particulate matter in surface waters of the senegal river basin. in the senegal river basin, tss are characterized by a high daily variability in their concentration, despite a fairly regular seasonal rhythm. tss remains relatively high for much of the year. daily rainfall and hydrological data were used to establish a relationship between river discharge and inverted tss concentration from landsat 8 satellite data for the site located at the outlet of the upper senegal river basin. shifts are noted between the peaks of tss observed often in july and those of rainfall (august) and discharge (september). satellite estimates are also used to assess the dynamics of tss in the senegal river basin and in the manantali dam. comparison of the tss concentration on either side of the manantali dam suggests low sediment retention in its reservoir, with possible peaks from time to time. the low concentrations of satellite derived tss are consistent with the ranges of tss deposits noted in the manantali dam reservoir. 42 faye et al. 2020 / journal of environmental geography 13 (1–2), 31–42. this study has demonstrated the value of including water colour data in environmental studies to expand and complement analyses carried out through in situ measurements at broader spatial and temporal scales. in the future, it is therefore necessary to continue the qualification of landsat-8 products, to carry out a postprocessing chain for landsat 8 images for "water colour" products, to develop regional algorithms for continental waters, to valorise products, to integrate water colour products into hydrological modelling (swat), to use water colour products for human health. acknowledgement the authors warmly thank the teams of the get laboratory (géosciences environnement toulouse) for their hospitality and the embassy of france which awarded us the grant of french cooperation which allowed the stay in france. references etcheber, h., schmidt, s., sottolichio, a., maneux, e., chabaux, g., escalier, j.m., h., derriennic, h., schmeltz, m., quemener, l., repecaud, m., woerther, p., castaing, p. 2010. monitoring water quality in estuarine environments: lessons from the magest monitoring programme in the gironde fluvial-estuarine system. hydrology and earth 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resources 5, 1048–1056. doi: 0.4236/nr.2014.516088 . introduction study area data and methods satellite data rainfall and discharge data estimation of tss results relationship between satellite reflectance and tss variation of tss in the upper basin as a function of rainfall and discharge data evolution of tss in the valley and delta of the river impacts of tributaries on water and sediment supply in the senegal river impacts of the manantali dam on sediment deposition in the senegal river discussion conclusion acknowledgement references classification of water quality of banat watercourses in serbia for the needs of irrigation journal of environmental geography 12 (1–2), 51–57. doi: 10.2478/jengeo-2019-0006 issn 2060-467x classification of water quality of banat watercourses in serbia for the needs of irrigation milica ilić, milica vranešević*, atila bezdan, boško blagojević university of novi sad, faculty of agriculture, department of water management, trg dositeja obradovića 8, 21000 novi sad, serbia *corresponding author, e-mail: milicaraj@polj.uns.ac.rs research article, received 1 march 2019, accepted 9 april 2019 abstract the composition of water used for irrigation has a significant impact on the production characteristics of the land, yield and irrigation equipment, and therefore its analysis, or assessment of the usability of irrigation water is very important. in this paper, the potential impact of the waters of the banat watercourses of moravica, karaš and nera is assessed on the basis of monthly water samples from the measuring stations of vatin, dobričevo and kusić, for the period of april-september from the year 2007 to 2017. the assessment was carried out using the classification of irrigation water: fao, usll and water categorization according to nejgebauer, and the serbian water quality index (swqi). for the needs of these classifications, a total of 20 water parameters were analyzed: quality, physical, chemical and biological parameters. according to all the classifications, the analyzed watercourses can be a good source of water for irrigation in terms of its quality, but with control and appropriate measures, in particular, the presence of bicarbonate, but also the ratio of na+ to ca2+ and mg2+. keywords: water quality, wqi, irrigation, vojvodina introduction the frequent occurrence of extreme drought periods is a major constraint on agricultural production that needs to meet the demands of increasing food demand. production under the irrigation systems can significantly increase yields, as indicated by the fact that about 40-50% of plant production in the world is realized on about 16% of arable irrigated area (savić et al., 2013). the result of irrigation is in the function of many factors, both natural and anthropogenic, and in terms of water, it is necessary to pay attention to the amount that is being applied, but also to pay attention to its quality. it is known that the composition of water used for irrigation has a major impact on soil characteristics, on yield and quality of cultivated plants, and on irrigation equipment (ayers and westcott, 1985; bortolini et al., 2018; bauder et al., 2011; fipps, 2003). increasing total salts, individual ions and their adverse relationship increases the risk of unwanted consequences. the assessment of the usability of water should be done according to parameters that have a direct impact on the soil in terms of its productivity and in accordance with its characteristics. the most common problems that occur with the use of inadequate irrigation water according to ayers and westcott (1985) can be divided into four groups: salinization, permeability, toxicity and miscellaneous problems. each of the problems can be expressed individually or in combination with other problems. the problem of salinity was observed at about 20-30 million ha of about 260 million hectares of irrigated land in the world (tanji and kielen, 2002). on some of the irrigated areas in vojvodina, heavily mineralized water has already led to the emergence of secondary salinization of soil. the problem of salinization is considered in terms of degradation of soil and accessibility of water to plants. stress caused by lack of water is similar to stress caused by excess of salt in the soil (munns, 2002). salinization has impact on growth of plants (ghoulam et al., 2002; munns, 2002), on their water regime, (ayers and westcott, 1976), mineral intake (grattan and grieve, 1999; hassan et al., 1970;), the capacity of the photosynthetic apparatus decreases with increased saturation (asharaf, 2001), etc. water of inadequate quality can cause deterioration of soil structure and thus reduce infiltration. reduced infiltration ability prevents plants from being supplied with the required amount of water. two factors related to the quality of water for irrigation that most affect the degree of infiltration are the total amount of salt in water, as well as the ratio of individual cations, more precisely the ratio of sodium to calicum and magnesium (ayers and westcott, 1985). some ions show toxic effects on plants by reducing their yield and quality, among which cl-, na+ and b are distinguished, and maximal allowed concentration depends on the plant species. irrigation equipment can be damaged by the presence of certain elements, which primarily refers to congestion of the emitters, and this results in poor uniformity of watering, leading to unequal development of plants. regarding the impact on the equipment of the irrigation system, suspended solids, bicarbonates, sulfides, manganese and iron are separated (bortolini et al., 2018). in order to prevent adverse effects, water quality assessment should become a necessary measure in the production under irrigation systems (joshi et al., 2009), whereby agronomic, ecological, technical and economic criteria can be applied. an analysis of water 52 ilić et al. 2019 / journal of environmental geography 12 (1–2), 51–57. quality parameters of three water courses in south banat was carried in this paper out in order to be classified in certain classes and in accordance with them defined the possibility of use for irrigation in the spatial sense. study area vojvodina belongs to the southern parts of the pannonian plain and is located between 44⁰ 38’ and 46⁰ 11’ northern geographic width, that is of 18⁰ 49’ and 21⁰ 00’ of eastern geographic length with an area of 21 506 km2. it represents one of the most productive areas in the world for agricultural production. however, agricultural production is not at the level at which it can be, and one of the main reasons is the lack of moisture during the vegetation period, which is due to high temperatures and insufficient precipitation (rajić, 2003). exceptional natural benefits, i.e. the plain of highly productive agricultural land and a relatively sufficient amount of surface water provide the possibility of intensive development of production under irrigation conditions. the government of the republic of serbia plans to increase the area under the irrigation systems and therefore it is necessary to consider all the factors of convenience for implementation or deficiencies in order to make a decision on potential irrigated areas. on existing systems, most water is obtained from surface flows, which indicates the importance of their quality assessment for these purposes (savić et al., 2013). watercourses moravica, karas and nera are located in the south banat district (eastern part of vojvodina, serbia) in settlements and the measuring stations with the same names: vatin, dobricevo, and kusic. out of the total area of the south banat, the agricultural area extends to around 80%, more precisely, 341.268 ha. figure 1 shows the location of the measuring points from which the analyzed samples were taken. materials and methods the quality of water of moravica (15+000), karaš (14+000) and nera (21+000) was assessed upon monthly samplings obtained in the period of april-september (vegetation period) from 2007 to 2017. data on physical, chemical and biological parameters of sample quality were taken from the hydrological yearbook of water quality of the republic hydrometeorological institute of serbia (hidmet, 2007-2010) and from the agency for the protection of the environment (sepa, 2011-2017).a detailed analysis of the parameters required for the application of the three water classification classes for irrigation has been carried out: fao classification (ayers and westcott, 1985), us salinity laboratory classification (ussl) (richards, 1954) and categorization of water according to nejgebauer, which is adapted to the natural conditions of vojvodina (belić et al., 2011). the basis of these classifications is the analysis of potential problems of salinization and alkalization, i.e. analysis of the concentration of total salt in water and of sodium, or its relation to divalent cations (ca2+ and mg2+), and fao classification provides more detailed analyses. in addition to the above classifications, water quality is assessed by the index method serbian water quality index (swqi) (www.sepa.gov.rs) which could be characterized as the general assessment of water quality. in addition to chemical parameters, this method also analyzes the biological and physical parameters of water quality. the analyzed quality parameters and their values are given in table 1. fig. 1 location of measuring point on watercourse moravica, karaš and nera ilić et al. 2019 / journal of environmental geography 12 (1–2), 51–57. 53 results and discussion moravica according to the fao classification criteria, moravica water qualities in terms of salinization alternately changed from first class, which has no limitations to moderate need for limitation (class ii). according to the influence of water on infiltration, the quality condition is similar. concentrations of na+ and of clare within are within the limits in which they do not exhibit toxic effects on plants. special attention should be paid to the possible effects of bicarbonate whose concentration was within the class of moderate use restriction (ii classes) with occasional occurrences of the need for serious limitations (iii classes). the percentage of moravica watercourse classes during the observed period according to the fao classification is given in table 2. table 2 percentual representation of certain moravica water classes according to the fao classification, vegetation period 2007-2017 potential problems class % salinity i 54.9 ii 45.1 infiltration i 52.9 ii 47.1 toxicity of na i 98.0 ii 2.0 toxicity of cli 100 effects of no3 i 98.0 ii 2.0 effects of hco3 ii 94.1 iii 5.9 ussl classification, based on the value of electrical conductivity and the sodium adsorption ratio, water samples moravica were classified mainly in the c2-s1 class, more precisely about 60% of the samples, and about 40% in the c3-s1 class (fig. 2). the ratio of sodium to calcium and magnesium is favorable and there is no danger in this respect. in terms of total salt, moravica water is characterized as "medium salty" and "salty" and therefore measures such as soil erosion, choice of cultures resistant to salt, and the inability to use this water on naturally poorly drained soils are necessary. the fact that benefits in favor of use is that class c3 is observed most often in months when irrigation is only applied intermittently (april, may), but due to occasional occurrence and in the irrigation season, regular controls and measures are in line with quality. according to nejgebauer's classification, the quality of water is "good" in most of the observed period, or more precisely, almost 80% of the samples. in addition, the samples were of "excellent quality", and only one sample is classed as unfit for irrigation, which may be the result of a local pollution just before water sampling (fig. 3). water quality of moravica, according to serbian water quality methodology can be defined as "bad" with approximately 60% of samples which belonged to that class (fig. 4). however, according to this method, such quality is useable for irrigation. however, the minimum quality index was 41, which is close to the limit of inapplicability (38). the remaining samples were "good", "very good" and in very few cases of "excellent" quality. table 3 shows the descriptive statistics of the moravica water quality index for the observed period, and the average monthly values and descriptive water quality indicator are shown in table 4 where it can be seen that the average values of the index corresponding to the "poor" water quality are closer to the lower border of quality "good" water. table 1 minimum, maximum, means and standard deviations (sd) of analyzed parameters in period april-september, 2007-2017 parameter moravica karaš nera min max mean sd min max mean sd min max mean sd ca2+ (mg/l) 33.0 89.0 64.7 15.3 2.6 109.0 70.6 23.4 37.0 67.4 51.3 6.4 mg2+ (mg/l) 12.0 57.0 33.3 10.7 3.0 122.0 85.36 10.2 2.0 10.0 5.2 1.6 na+ (mg/l) 8.4 80.5 42.7 15.2 4.5 29.0 14.9 5.3 0.7 9.0 5.5 1.7 k+ (mg/l) 0.9 10.6 4.6 2.1 1.2 7.5 6.4 2.1 0.5 4.6 1.7 0.7 so42(mg/l) 19.0 73.0 40.5 10.5 20.0 56.0 34.6 8.5 13.0 290.0 36.4 42.3 cl(mg/l) 11.4 73.0 27.7 11.5 6.2 24.7 11.6 3.2 3.6 19.0 6.1 2.5 no3-n (mg/l) 0.05 9.30 0.51 1.35 0.11 3.78 0.92 0.60 0.02 2.71 0.49 0.38 co32(mg/l) 0.0 31.1 3.5 7.8 0.0 19.0 2.5 5.3 0.0 27.6 2.5 4.6 hco3(mg/l) 152.0 534.0 385.7 99.9 152.0 354.0 254.2 33.82 105.0 362.0 164.0 34.5 ec ( s/cm) 281 913 655.4 170 317 668 466.9 60.4 224 364 292.3 31.4 tds (mg/l) 207 560 431.2 92.2 206 458 290.4 39.7 138 226 181.3 17.4 ph value 6.4 8.7 7.9 0.4 7.7 8.4 8.1 0.2 7.7 8.8 8.2 0.2 temperature (oc) 13.7 28.6 21.1 4.1 10.2 36.0 19.5 4.6 8.5 28.0 18.2 4.9 oxygen saturation (%) 15 184 75.7 39.1 71 145 95.4 11.2 72 128 99.5 10.0 bod5 (o2 mg/l) 1.0 13.6 3.4 2.4 1.0 5.5 2.2 0.9 0.8 3.5 1.7 0.6 nh4-n (mg/l) <0.02 0.65 0.08 0.11 <0.02 0.81 0.09 0.11 <0.02 0.25 0.05 0.04 total oxides of nitrogen (mg/l) 0.06 9.37 0.53 1.36 0.13 3.84 0.94 0.60 0.03 2.71 0.50 0.38 orthophospates (mg/l) 0.02 0.85 0.23 0.17 0.01 0.81 0.09 0.11 0.02 0.85 0.23 0.17 suspended solids (mg/l) 2 213 30.7 38.3 2 208 37.8 46.4 1 205 25.8 40.1 sar 0.30 2.38 1.06 0.35 0.14 0.78 0.42 0.13 0.03 0.37 0.2 0.06 54 ilić et al. 2019 / journal of environmental geography 12 (1–2), 51–57. fig. 2 moravica water classes according to ussl classification, vegetation period 2007-2017 fig. 3 percentual representation of certain moravica water classes according to nejgebauer classification, vegetation period 2007-2017 fig. 4 percentile representation of certain moravica water classes according to swqi methodology, vegetation period 2007-2017 table 3 minimum, maximum, mean and standard deviations (sd) of swqi, vegetation period april-september, 2007-2017 swqi minimum 41 maximum 91 mean 68 sd 11 table 4 average monthly values of index of moravica water quality, vegetation period 2007-2017 april may june july august september 81 71 63 62 61 68 good bad bad bad bad bad karaš the water quality of karaš varied only in one class according to each fao classification criteria (table 5). according to the influence of water on permeability all samples are classified in the class of moderate usage limitation (ii classes), as well as due to the diverse effects of bicarbonate. according to other criteria, water is of the highest quality for irrigation purposes. ussl classification classifies water in class c2-s1, i.e. "salty" water without a significant risk of the effect of adsorbing harmful sodium in terms of alkalization. figure 5 shows that the ec values varied from lower to upper limit of the class, while all sar values are closer to the lower limit value of the class. table 5 percentile representation of individual water classes of karaš according to the fao classification, vegetation period 2007-2017 potential problems class % salinity i 100 infiltration ii 100 toxicity of na i 100 toxicity of cli 100 effect of no3i 100 effect of hco3ii 100 mild criteria have a classification according to nejgebauer, and it places this water in the first class, i.e. water of "excellent" quality for irrigation, which shows that there are no risks of harmful effects of salt in quantitative or qualitative terms. figure 6 shows the results of the swqi method. this classification shows a higher variability of water quality, but it also takes into account other parameters, in addition to chemical, physical and biological. an equal number of samples, about 40% belong to "very good" and "good" water quality, while others are classified as "excellent" and "bad" quality. on this watercourse, quality was not unsuitable for use during the analyzed period. the basic statistical indicators of the water quality index karaš are shown in table 6. average monthly values of the index corresponded to "very good" and "good" quality (table 7). ilić et al. 2019 / journal of environmental geography 12 (1–2), 51–57. 55 fig. 5 classes of water of karaša according to ussl classification, vegetation period 2007-2017 fig. 6 percentile representation of individual water classes of karaša according to swqi methodology, vegetation period 2007-2017 table 6 minimum, maximum, mean and standard deviations (sd) of swqi, vegetation period april-september, 2007-2017 swqi minimum 63 maximum 95 mean 82 sd 7 table 7 average monthly values of the quality index of water of karaš, vegetation period 2007-2017 april may june july august september 87 84 76 78 80 86 very good very good good good good very good nera as well as on the karas watercourse, nera's water quality did not exhibit variability outside the class-defined by fao criteria (table 8). problems related to soil infiltration are moderate, as well as problems that can be caused by elevated concentration of bicarbonate. in terms of total salt, i.e. accessibility of water to the plants, there are no problems, nor in terms of toxicity and the content of nitrates. figure 7 shows the results of nera water quality according to the ussl classification where it can be observed that the ec and sar values are relatively low and low variability. about 95% of the samples are categorized into c2-s1 and 5% in c1-s1. by classification by nejgebauer, all water samples are classified in "excellent" quality (fig. 8). table 8 percentile representation of representation of certain nera water classes according to the fao classification, vegetation period 2007-2017 potential problems class % salinity i 100 infiltration ii 100 toxicity of na i 100 toxicity of cli 100 effects of no3i 100 effects of hco3ii 100 fig. 7 nera water classes according to ussl classification, vegetation period 2007-2017 56 ilić et al. 2019 / journal of environmental geography 12 (1–2), 51–57. fig. 8 percentile representation of certain nera water classes according to nejgebauer classification, vegetation period 20072017 according to swqi methodology the quality of water varied from varied from "good" to "excellent". half of the samples were characterized by excellent quality, about 40% of the samples belonged to the class of "very good" and about 10% of the class of "good" water (fig. 9). fig. 9 percentile representation of certain nera water classes according to swqi methodology, vegetation period 2007-2017 table 9 shows the minimum, maximum and mean value of the nera water quality index, as well as the standard deviation value. the average value of the index, although indicating "very good" quality, is at the "excellent" quality limit (90). the average values for each analyzed month and their descriptive indicator are shown in table 10. table 9 minimum, maximum, mean and standard deviations (sd) swqi of nera, vegetation period april-september, 20072017 swqi minimum 77 maximum 97 mean 89 standard deviation 4 table 10 average monthly values of the water quality index of nera, vegetation period 2007-2017 april may june july august september 85 82 80 79 79 84 very good good good good good very good conclusion according to all water classifications, the analyzed watercourses are usable for irrigation, where the best quality is characterized by the nera water, then karas and moravica. all three watercourses require control over the content of total salt, due to the impact on soil and plants, as well as the ratio of sodium concentration to calcium and magnesium (sar value), due to a moderate danger to the infiltration properties of the soil. special control is needed on the concentration of bicarbonates from which there is a greater risk of occurrence of various adverse effects on the soil, irrigated plants and irrigation equipment. the results according to the nejgebauer classification adapted to the conditions of vojvodina are most favorable for use. according to this classification, the quality of moravica is "good" (ii class) to about 80% of the samples, the remaining samples were "excellent" quality (class i), except for one unsuitable for use, while karas and nera, their samples are classified as 100% in the "excellent" class of quality (class i). although it may give the most benign results because it is adapted to the natural characteristics of the area being analyzed, it includes a modest amount of data for classification. the fao classification is more detailed, but like the ussl classification of a different local character, the direction of future research could be directed to modification towards the natural factors of vojvodina. the swqi methodology includes a wider range of parameters being analyzed, but not all of them are of paramount importance for irrigation purposes, nor are the class boundaries defined accordingly. however, the occasional analysis of these parameters is desirable, with the possible adjustment of the border values for these purposes. acknowledgement this research was supported by the projects of the european regional development fund: interreg-ipa 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(http://www.sepa.gov.rs/index.php?menu=5000&id=13&akcija= showexternal) richards, l. a. 1954. diagnosis and improvement of saline and alkali soils. agriculture handbook no. 60. united states department of agriculture, riverside, california. savić, r., pejić, b., ondrašek, g., vranešević, m., bezdan, a. 2013. utilisation of natural resources for irrigation in vojvodina (in serbian). agro-knowledge journal 14 (1), 133–142. tanji, k.k., kielen, n.c. 2002. agricultural drainage water management in arid and semi-arid areas. fao irrigation and drainage paper 61, 188p. online available at: http://www.fao.org/3/a-ap103e.pdf introduction study area materials and methods results and discussion moravica karaš nera conclusion acknowledgement references journal of environmental geography journal of environmental geography 6 (3–4), 13–20. doi: 10.2478/jengeo-2013-0002 issn: 2060-467x estimation of soil material transportation by wind based on in situ wind tunnel experiments andrea farsang 1* , rainer duttmann 2 , máté bartus 1 , józsef szatmári 1 , károly barta 1 , gábor bozsó 3 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 department of geography, division of landscape ecology and geoinformatics, christian-albrechts-university kiel, germany 3 department of mineralogy, geochemsitry and petrology, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: farsang@geo.u-szeged.hu research article, received 10 june 2013, accepted 21 august 2013 abstract 25% and 40% of territory of hungary is moderate to highly vulnerable to deflation. however, precise estimates about the soil loss and related losses of organic matter and nutrients due to wind erosion are missing in most cases. in order to determine magnitudes of nutrient masses removed at wind velocities that frequently occur in se hungary, in-situ experiments using a portable wind tunnel have been conducted on small test plots with an erosional length of 5.6 m and a width of 0.65 m. the wind tunnel experiments have been carried through on a chernozem which is typical for this region. in order to compare the effects of soil coverage on the masses of blown soil sediment and adsorbed nutrients, two soil surface types have been tested under similar soil moisture und atmospheric conditions: (1) bare soil (dead fallow) and (2) bare soil surface interrupted by a row of maize plants directed downwind along the center line of the test plots. the results of our experiments clearly show that a constant wind velocity of 15 m s -1 (at a height of 0.3 m) lasting over a short time period of 10 minutes can already cause noticeable changes in the composition and size of soil aggregates at the top of the soil surface. due to the grain size selectivity of the erosive forces the relative share of soil aggregates comprising diameters > 1 mm increased by 5-10% compared with the unaffected soil. moreover it has shown that short time wind erosion events as simulated in this study can result in erosion rates between 100 and 120 g m -2 , where the erosion rates measured for bare soils are only slightly, but not significantly higher than those of the loosely vegetated ones. soil samples taken from sediment traps mounted in different heights close to the outlet of the wind tunnel point to an enrichment of organic matter (om) of about 0.6 to 1 % by mass referred to the control samples. from these findings has been calculated that the relocation of organic matter within short term wind erosion events can amount to 4.5 to 5.0 g om m -2 . with the help of portable field wind tunnel experiments we can conclude that our valuable, high quality chernozems are struck by wind erosion mainly in drought periods. keywords: deflation, wind tunnel experiment, nutrient transport introduction it is well-known that among other processes of soil degradation, wind erosion can cause enormous dama ges on the regional as on the global scales. for this reason, research on this topic has started early (chepil 1942, 1955; chepil and woodruff 1963; woodruff and siddoway, 1965). however, for a long time attention was mainly given to the physical mechanisms and to the measurement of wind erosion under field and lab conditions (gillette, 1978; bódis and szatmári, 1998). since the 1980s research focused on the modeling of wind erosion processes including the calculation of soil erosion rates at different spatial and temporal scales and, especially, the estimation of the losses of organic matter and nutrients caused by deflation (zobeck and fryrear, 1986; zobeck et al., 1989; sterk et al. 1996; larney et al. 1998; bach, 2008). the amount of nutrient loss per hectare varies within a broad range, depending on the soil type, the physical properties and the organic matter content. for stronger wind erosion events neemann (1991) reports about nutrient losses of about 150 kg n ha -1 , 200 kg p2o5 ha -1 , 200 kg k2o ha -1 , 200 kg mgo ha -1 and 600 kg cao ha -1 (neemann, 1991, charles et al., 2002, sankey et al., 2012). in hungary, the deflation preferentially occurs in regions covered with sandy soils (e.g. the danube-tisza interfluve, nyírség). hence, these areas form the recent center of soil erosion research (borsy, 1972; harkányiné and herkó, 1989; lóki and schweitzer, 2001; mezősi and szatmári, 1998; mucsi and szatmári, 1998; szatmári, 1997, 2005) although the vulnerability of chernozem soils to wind erosion has been already emphasized in earlier research (bodolayné, 1966; bodolayné et al., 1976). the vulnerability assessment of the hungarian soils to deflation has been made possible after finalizing the 1:100.000 soil maps, which have a special focus on physical diversity (várallyay et al., 1979, 1980). the assessment of wind erosion risk indicates that 26% of the total area of hungary is covered with highly 14 farsang et al. (2013) vulnerable sandy soils, another 40% of the country has been classified as medium vulnerable, corresponding with the wide spreading areas composed of sandy loam and loam (lóki, 2003). as stated by baukó and beregszászi (1990) in their case study in békés county, these soils bear large economic potential, which increases the need for sustainable land use practices. to-date only little is known about the quantities of wind-driven soil and nutrient losses from chernozems as they are typical for the south eastern parts of the great hungarian plain (apátfalva). in order to gain knowledge about the magnitudes of deflation rates of mineral soil, organic matter and nutrients, wind tunnel experiments have been performed under controlled conditions. although wind tunnel experiments have been widely used in many other regions (e.g. maurer et al., 2006; bach, 2008; fister and ries, 2009), this paper describes the first applications of an in-situ wind tunnel experiment in hungary. the major objectives of this study are (i) to compare the rates of soil loss caused by winds of frequent velocity on uncovered and loosely covered soil surfaces as they are typical for most of the wind erosion events in this area, (ii) to analyse the changes of the above-ground soil structure and (iii) to calculate the magnitudes of humusand of the nutrient losses during wind storm events of defined intensity. study area the study area is located in the csongrád -plain micro region (fig. 1). the elevation of the area ranges between 79.5 and 107.6 m forming nearly a perfect plain. the clayey, loamy subsurface sediments are co vered by infusional loess of various depths. the climate of the area is warm and dry with an annual average te mperature of 10.3 °c and an annual precipitation of around 560–570 mm. the aridity index (ratio of the potential maximal evaporation and the annual precipitation) is around 1.3, and may have a considerable effect on the deflation of the soil. the prevailing wind direction is nw, but winds from se are also frequent (dövényi, 2010). the synops data, which provide mainly hourly data, measured in szeged weather station (wmo index 12982). in the cases of all wind velocity data 160° is dominant, but the strongest winds come from 320°, so this direction is chosen to set the model (fig. 2). fig. 2 wind direction change at szeged in aspect of wind velocity (march-april, 2000-2011) the typical soil type is a chernozem according to wrb, 2006, having a loamy, at some places clayey loam texture (fig. 3) and high humus contents in the a-horizons (4.5-4.8%). the carbonate content varies between 4-12% by weight. during the experiments, the water content of the soil was 7–8 v/v%. fig. 1 potential wind erosion map of hungary with the studied area (0: insignificant, 1: slight, 2: moderate, 3: severe) (lóki, 2000) estimation of soil material transportation by wind based on in situ wind tunnel experiments 15 fig. 3 grain size distribution of the chernozem soil in the study area methods the undisturbed surface soil was measured in a portable and adjustable 12 m long field wind tunnel (fig. 4) in situ on the study plot in the summer of 2011. experiment “a” was conducted upon a non-cultivated, plant-free surface. the “b” series simulate the effects of a loosely vegetated surface. for this purpose a row of maize plants with a height of 25-30 cm and a spacing of 10 cm was placed in the center of the wind tunnel (fig. 5). for both series three parallel deflation experiments where carried through each one with a duration of 10 minutes and approximately 15 ms -1 wind speed. wind velocity has been measured along horizontal and vertical profile lines during all experiments (fig. 7) using a lambrecht jürgens 642 anemometer. the ground area blown within the wind tunnel covers 3.36 m 2 . measurements of wind velocity confirmed the existence of a logarithmic shaped boundary layer of a thickness of about 35.1 cm. the threshold wind velocity in both experiments was observed at 13 ms -1 . following each wind experiment both the surface soil and the rolling soil fractions were sampled. the latter were collected in boxes positioned at the end of the tunnel. the mwac (modified wilson and cook) traps at 5, 15, 25, 35, 45 and 55 cm heights at the end of the tunnel were emptied (fig. 6). the samples were air dried, and after the appropriate preparation, the following parameters were determined: distribution of aggregates by sieving, “arany” yarn test according to the msz-08-0205:1978 fig. 4 the portable wind tunnel fig. 5 surface soil of the two experiment series: “a” series with an undisturbed surface soil, “b” series on a maize field fig. 6 the location of the soil sample points, the mwac traps and the sediment traps at the end of the tunnel about 15 ms -1 with 16 farsang et al. (2013) specification, ph(h2o), carbonate content according to the msz-08-0206/2:1978 specification, and the organic matter content according to the msz 21470/52:1983 specification. the total element content of the soil and the captured sediment was determined by xrf horiba jobinyvon xgt-5000. the particle size distribution was measured by fritsch analysette 22 microtel plus. results and discussion analyses of the wind profiles reveal significant differences between the "a" series (bare soil) and the "b" ("maize") series. figure 5 clearly shows the influence of a different surface roughness and surface structure on the changes of the wind velocity over the whole crosssection of the wind tunnel. the isotache profile of the “a” series, expectedly reveals a decrease of wind velocity close to the ground, depending on the soil roughness cause by the coarser aggregate on top of the soil. the z0-value has been calculated at 0.25 mm. at a height of 10 cm the wind velocity increases up to 13 m s -1 while it reaches its original velocity of 15 ms -1 in a height of 20 cm. surprisingly, the isotache profile of the “b” series shows a different behaviour. in contrast to other studies (bolte, 2008) that show a strongly reduced wind velocity behind wind breaking obstacles, we found only a minor decrease in wind velocity within and behind the row of maize plants, and even a higher wind speed compared with the same heights of the series "a" experiments (fig. 7). this fact suggests the occurrence of vortex movements around the single maize plants causing an increase in wind velocity up to 16-17 m s -1 which might contribute to higher deflation rates along plant rows oriented in downwind direction at this stage of growth. the 10 minutes wind event had a significant impact on the relative percentage of aggregate sizes in the surface soil (fig. 8, table 1). the experiments show that the dust fraction was reduced, and therefore the proportion of larger aggregates increased in the top 5 cm of the soil. it is noteworthy that during the “b” experiment series, the ratio of 1< mm aggregates in the surface layer increased by 5 – 10% compared to the original soil (fig. 8.).the largest saltation movement was caused by the increase of the wind velocity along the outer sides the maize row. comparing the original surface soil and the aggregate composition of the material collected in the traps (mass%, n = 3) afterwards the “a” series experiment, it is obvious that 58% of the soil material trapped in the recessed traps consisted of aggregates with a diameter of 1 to 4 mm (table 1). compared with the aggregate composition of the original surface soil, in both experiment series the diameter of the soil crumbs increased significantly in the trapped soil material (7%). during the 16-17 ms -1 wind speeds of the “b” experi fig. 7 the wind profiles (ms -1 ) of the two experiment series (left: “a” series, right: “b” series) fig. 8 change of the aggregate structure (%) of the surface soil (left: “a” experiment series, right: “b” experiment series) estimation of soil material transportation by wind based on in situ wind tunnel experiments 17 ment series, more 4 mm and larger aggregates where moved. on average 20% of the trapped soil material in the traps had an aggregate diameter larger than 4 mm. the organic matter (om) content of the accumulated material in the traps increased (fig. 9). by dividing the om content of the material captured in the mwacs trap, by the om content of the original su rface soil, an enrichment factor of 1.1 to 1.2 depending on the strength of the wind can be found for the traps at a height of 15 and 25 cm. the material taken from the traps at a height between 0.15 m and 0.55 m, the om content showed an increase of 0.6 – 1% compared to original soil (fig. 10, table 2). fig. 9 amount of the humus the effect of the soil movement during the 10 minute wind events on the amount of accumulated soil material in the trap has been quantified, given the area of the surface exposed to the wind and the size of the surface of the mwac traps (table 2). the majority of the soil movement consist of rolling soil material.the amount of trapped soil material not show significant differences; in case of the ”a” series 97 g m -2 of rolling soil material was registered while during the “b” series 59 g m -2 was recorded. in the first place, the soil with aggregates smaller than 0.25 mm (soil dust) was collected in the mwac traps, which was in case of the “a” series 10.7 % of the total transported material, while during the “b” series this was 17 .4 %. the average soil movement during the “a” measurement series was 107 g m -2 , and during the “b” measurements series 115 gm -2 . from the total amount of transported soil, just the suspended fine fractions are accumulating in the mwac traps at larger distance; during the 10 minutes 15 ms -1 wind event, an amount of 15 g m -2 was registered. the amount of relocated humus (g m -2 ) movement was calculated based on the total amount of soil material that was transported during the wind event and the humus content of the accumulated sediments in the traps. the om content in the sediment traps (above 0.15 m) was 0.6–1% higher than that of the original surface soil (fig. 9-10). the amount of relocated om content caused by deflation could reach up to 4.5–5.0 g m -2 (table 2). fig. 10 variation of the amount of humus enrichment ratios in the sediment collected with mwac traps at 5, 15, 25, 35 and 45 cm height (red: “a” experiment series, blue: “b” experiment series macro elements (p, ca, k) do not show any increase in the transported soil fraction, their enric hment ratios vary between 0.95 and 1.09 (table 3-5). the 10 minute long wind experiment with 15 ms -1 wind speed transported 0.1 g m -2 of p, 1.6 g m -2 of k and 2.9 g m -2 of ca. comparisons between the amount of relocated nutrients calculated in this study and those amounts reported from other studies –are complicated, because of differing wind tunnel characteristics, differing initial conditions and varying soil properties. table 1 the aggregate composition of the original surface soil and the, in the traps accumulated, soil material (mass%, n=3) mm „a” series surface m/m% standard deviation „a” series trap m/m% standard deviation „b” series surface m/m% standard deviation „b” series trap m/m% standard deviation >4 14.4 3.9 11.3 0.2 15.4 1.7 19.9 9.2 2–4 18.4 1.7 25.7 1.5 18.3 0.5 27.8 3.6 1–2 25.1 1.2 32.3 1.8 25.4 1.04 28.8 4.9 0.5–1 19.0 1.4 18.2 0.6 19.3 0.6 14.7 1.6 0.25–0.5 9.7 1.3 6.3 0.5 9.8 0.6 4.8 0.5 <0.25 13.4 2.6 6.1 0.9 11.8 0.9 3.9 0.2 18 farsang et al. (2013) table 2 amount of the transported soil (g m -2 ), the relocated humus (g m -2 ) and the humus enrichment ratios during the two experiment series (a and b) (wind speed 15 m s -1 , 10 minute long single experiments) . amount of transported soil (average) (g m -2 ) om (%) enrichment ratios amount of relocated humus (g m -2 ) (average) standard deviation om% eroded/original soil the rolling soil fraction collected in recessed boxes at the end of the tunnel a box 97.0 4.47 0.08 0.98 4.34 b box 95.0 4.44 0.17 0.95 4.22 the suspended soil fraction collected with mwac traps a 5 cm 5.53 4.86 0.31 1.07 0. 27 a 15 cm 2.35 5.45 0.12 1.20 0.13 a ≥25 cm 2.12 5.37 0.12 1.18 0.11 b 5 cm 8.51 4.56 0.03 0.96 0.39 b 15 cm 5.24 5.01 0.45 1.06 0.26 b ≥25 cm 6.25 4.85 0.11 1.02 0.303 total transported humus (a series): 4.85 g m -2 total transported humus (b series): 5.17 g m -2 table 3 amount of the transported soil (g m -2 ), the relocated p (g m -2 ) and the p enrichment ratios during the experiments (wind speed 15 m s -1 , 10 minute long single experiments) amount of transported soil (average) (g m -2 ) p (ppm) enrichment ratios amount of relocated p (g m -2 ) (average) standard deviation p eroded/original soil the rolling soil fraction collected in recessed boxes at the end of the tunnel box 96.0 1004.2 249 1.07 0.096 the suspended soil fraction collected with mwac traps 5 cm 5.53 887.8 63.2 0.95 0.005 15 cm 2.35 903.3 107.5 0.97 0.002 ≥25 cm 2.12 861.6 63.4 0.92 0.002 total transported p/experiments: 0.106 g m -2 table 4 amount of the transported soil (g m -2 ), the relocated k (g m -2 ) and the k enrichment ratios during the experiments (wind speed 15 m s -1 , 10 minute long single experiments) amount of transported soil (average) (g m -2 ) k (ppm) enrichment ratios amount of relocated k (g m -2 ) (average) standard deviation k eroded/original soil the rolling soil fraction collected in recessed boxes at the end of the tunnel box 96.0 15018 2072 1.00 1.44 the suspended soil fraction collected with mwac traps 5 cm 5.53 16167 1916 1.06 0.089 15 cm 2.35 16374 2204 1.08 0.039 ≥25 cm 2.12 16493 929 1.09 0.035 total transported k/experiments: 1.605 g m -2 table 5 amount of the transported soil (g m -2 ), the relocated ca (g m -2 ) and the ca enrichment ratios during the experiments (wind speed 15 m s -1 , 10 minute long single experiments) amount of transported soil (average) (g m -2 ) ca (ppm) enrichment ratios amount of relocated ca (g m -2 ) (average) standard deviation ca eroded/original soil the rolling soil fraction collected in recessed boxes at the end of the tunnel box 96,0 26961 5925 0.9 2.59 the suspended soil fraction collected with mwac traps 5 cm 5.53 29253 5862 0.97 0.162 15 cm 2.35 31753 5900 1.04 0.075 ≥25 cm 2.12 31983 1848 1.08 0.068 total transported ca/experiments: 2.89 g m -2 estimation of soil material transportation by wind based on in situ wind tunnel experiments 19 bielders et al. (2002) calculated nutrient balance of sandy soil triggered by three natural storms in sahel. they measured a soil loss of about 0.3-1.9 kg m -2 . because of the low nutrient content of the native soil, total nutrient losses remained very low: p loss was calculated at 9-65 mg m -2 , k 20-128 mg m -2 and ca loss 7-62 mg m 2 . the study of sterk et al. (1996) was conducted to quantify nutrient losses by saltation and suspension transport. during two convective storms mass fluxes of wind-blown particles were measured in niger on sandy soil. the trapped material was analysed for total element content (k, p, c, n). the following nutrient losses were estimated: 5.7 g m -2 k and 0.61 g m -2 p. in the study of sankey et al. (2012) the nutrient concentrations by mehlich3 extraction (p, k, mg, cu, fe, mn, al) in windtransported sediment were determined. the soils were collected from burned and unburned soil surfaces in idaho, usa. they estimated 0.256 g m -2 y -1 p mobilization and 1.451 g m -2 y -1 k mobilization. nutrient transport determined by us are congruent to the values measured by sterk et al. (1996) because their experiments also focused on wind events and the total element was investigated from captured sediment, as well. conclusion during this research measurements with a field wind tunnel were executed on the chernozem soils on the southern part of the great hungarian plain. the experiments were repeated three times with two different types of surface cover . they make obvious that already short-time wind events of a wind velocity of 15 ms -1 , can erode more than 100 g m -2 . if one hypothetically assumes that the simulated conditons would be true for a complete field this would equalize a loss of 1 ton of treasurous and highly fertile agricultural soil per hectare that would have been lost from this material, the main part is transported on or close to the surface. only 10 to 15% is moved in suspended form. this material can be transported over a much larger distance, and this way losing permanently its significantly higher humus content than the original soil, which is crucial for the agriculture. acknowledgements this research has been financially supported by the otka k 73093 and otka in 83207 and támop4.1.1. c-12/1/konv-2012-0012 ”zenfe” projects. references bach, m. 2008. aolische stofftransporte in agrarlandschaftem. phd dissertation. christian-albrechts universitat, kiel. baukó, t., beregszászi, p. 1990. egyszerűsödő agrár-térszerkezet – fokozódó szélkárosodás békés megyében (simplifying spatial struture of agricultural lands – increasing wind erosion in békés county). környezetgazdálkodási évkönyv 1989. békéscsaba, 87–95. bielders, c.l., rajot, j.l., amadou, m., 2002. transport of soil and nutrients by wind in bush fallow land and traditionally managed cultivated fields in the sahel. geoderma 109, 19–39. bódis, k., szatmári, j. 1998. eolikus geomorfológiai vizsgálatok ddm felhasználásával (eolic geomorphological investigations using dem). in: vii. térinformatika a felsőoktatásban szimpózium. budapest, 102–107. bodolay, i.-né, 1966. a széleróziót befolyásoló változó talajfizikai tulajdonságok (physical properities influencing wind erosion). agrokémia és talajtan, 15, 372–383. bodolay, i.-né, máté, f., szűcs, l. 1976. a szélerózió hatása a bácskai löszháton (effect of wind erosion on bácsa loess plateau). agrokémia és talajtan 25, 96–103. bolte, k. 2008. untersuchungen zur feuchteabhangigen dynaik des bodespezifischen erosionwiderstandes bei bewindung unter windkanalbedingungen schriftenreihe des institut für pflanzenernahrung und bodenkunde universitat kiel. 146 p. borsy, z. 1972. a szélerózió vizsgálata a magyarországi futóhomok területeken (investigation of wind erosion on sandland areas of hungary). földrajzi közlemények 20 (2–3), 156–160. chepil, w.s. 1942. relation of wind erosion to the water-stable and dry clod structure of soil. soil science 55, 275–287. chepil, w.s. 1955. factors that influence clod structure and erodibility of soil by wind: v. organic matter at various stages of decomposition. soil science 80 (5), 413–421. chepil, w.s., n.p. woodruff 1963. the physics of wind erosion and its control. advances in agronomy 15, new york: academic press inc., 302 pp. dövényi, z. 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(map of pedological factors determining the site conditions in hungary ii). agrokémia és talajtan 29. 35–76. woodruff, n.p., siddoway, f.h. 1965. a wind erosion equation. soi. sci. soc. am. proc. 29, 602–608. zobeck, t., fryrear, d.w. 1986. chemical and physical characteristics of windblown sediment. transaction of the asae 29, 1037– 1041. zobeck, t., fryrear, d.w., petit, r. d., 1989. management effects on winderoded sediment and plant nutrients. j. soil and water conservation. 44, 160–163. journal of environmental geography journal of environmental geography 7 (1–2), 49 – 56. doi: 10.2478/jengeo-2014-0006 issn: 2060-467x effect of climate change on the hydrological character of river maros, hungary-romania györgy sipos * , viktória blanka, gábor mezősi, tímea kiss, boudewijn van leeuwen department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: siposgy@geo.u-szeged.hu research article, received 28 february 2014, accepted 13 march 2014 abstract it is highly probable that the precipitation and temperature changes induced by global warming projected for the 21st century will affect the regime of carpathian basin rivers, e.g. that of river maros. as the river is an exceptionally important natural resource both in hungary and romania it is necessary to outline future processes and tendencies concerning its high and low water hydrology in order to carry out sustainable cross-border river management. the analyses were based on regional climate models (aladin and remo) using the sres a1b scenario. the modelled data had a daily temporal resolution and a 25 km spatial resolution, therefore beside catchment scale annual changes it was also possible to assess seasonal and spatial patterns for the modelled intervals (20212050 and 2071-2010). those periods of the year are studied in more detail which have a significant role in the regime of the river. the study emphasizes a decrease in winter snow reserves and an earlier start of the melting period, which suggest decreasing spring flood levels, but also a temporally more extensive flood season. changes in early summer precipitation are ambiguous, and therefore no or only slight changes in runoff can be expected for this period. nevertheless, it seems highly probable that during the summer and especially the early autumn period a steadily intensifying water shortage can be expected. the regime of the river is also greatly affected by human structures (dams and reservoirs) which make future, more detailed modelling a challenge. keywords: river maros, catchment hydrology, climate change, rcms introduction river maros has always been an important natural resource on the southern great plains of the carpathian basin. the amount of water it drains annually equals to the total water consumption of hungary. although only part of this water is utilised, the river is by far the most significant water resource for irrigation and industrial activity in the region. besides, it also feeds a thriving riparian ecosystem and has a unique geomorphological character. the availability and quality of its resources are endangered by several factors. from among these the short and long term effects of human interventions and that of climate change have to be emphasized. the future of river maros and adjacent territories is determined basically by the amount of water drained by the river. previous research has demonstrated that the late pleistocene and holocene evolution of the river has primarily been affected by climatic variations (kiss et al., 2013). the fluvial system is still very active and it is highly sensitive to external forcing factors (kiss and sipos, 2007), from which recent climate change is getting to be more and more pronounced. in the near future climate change will supposedly alter the duration and pattern of both flood and low water discharges and the intensity of channel development. large number of investigations have demonstrated that the actual changes of the temperature and precipitation will have significant effects on all factors of the environment, and can also alter the rate of geomorphologic, and especially fluvial processes (dikau and schrott, 1999). the possible causes of climate change concerning river hydrology and fluvial activity has been addressed by several studies recently. these apply for the simulations climate models to predict future deviations in temperature and precipitation. for concluding general trends on large catchments global climate models (gcm) are applied by several studies (e.g. boyer et al., 2010; chung and jung, 2010; zeng et al., 2012), however, differences in the topography and hydrology of subcatchments would call for the downscaling of global models (dobler et al., 2012), or the application of regional climate models (rcm) at best (veijalainen et al., 2010). studies agree, however that the application of several models and emission scenarios can increase the reliability of results (kay et al., 2006; smith et al., 2013). however, moderate analyses usually apply the a1b sres scenario for calculations. one of the most important problems addressed by hydrologists is the expectable change in flood frequency and flood height. in this respect variations in snow/precipitation ratio and seasonal rainfall distribution are key parameters (boyer et al., 2010; bell et al., 2012). as a consequence of these flood hazard can increase even if total annual runoff is expected to decrease (kay et al., 2006; zeng et al., 2012). furthermore, in several 50 sipos et al. (2014) cases the elongation of the flood season, can result a lower predictability concerning flood timing in the future (dobler et al., 2012). on the other end water shortage may pose serious problems for water managers (lorenzo-lacruz et al., 2010; koutroulis et al., 2013). beside well known consequences, such as future limitations in water use and related agricultural, economic and social conflicts, even accelerated geomorphological change can be expected at certain catchments (smith et al., 2013). concerning low stage periods predictability of river hydrology is highly limited by human interventions (e.g. water retention, irrigation), which is a problem on most of engineered rivers (kiss and blanka, 2012). among these circumstances adaptation will be a key issue. in this study a conceptual framework was set up for the trends in catchment scale hydrological changes concerning river maros. the major questions were: (1) what changes can be expected in temperature and precipitation on the watershed of the river in the 21st century? how these changes can affect the regime of the river and the total annual volume of water drained? the tendencies of future changes were explored by using regional climate models. the study aims to provide base for future hydrological modelling and runoff calculations. study area the catchment of river maros is located in the southeastern part of the carpathian basin. 92% of its total area (30 000 km2) belongs to romania, the remaining 8% to hungary (fig.1). river maros and its tributaries are mostly fed by precipitation and overland flow. due to the geology of the catchment (overwhelmingly volcanic and crystalline rocks) and the high proportion of very steep slopes floods rise relatively quickly, and last for only a short time. two major floods may develop annually on the river. the first is due to snowmelt in early spring, the second is caused by early summer rainfall usually in june (fig. 2). following the april-june floods the rest of the year is characterized by low stages, which last for approximately 10 months from june till march, with a minimum water delivery at october (boga and nováky 1986). fig. 1 the location of the maros catchment within the carpathian basin the mean annual discharge of the river is 160 m 3 /s. peak and minimum discharges are around 20002500 m 3 /s and 30-50 m 3 /s, respectively. the area is dominated by westerly winds, though from time to time the effect eastern -european and mediterranean air masses are also significant (csoma 1975). the annual mean temperature on the catchment is between 4–11 °c, though there is a great territorial variation, determined primarily by the t opography. as a general rule the value of the mean annual temperature is increasing continuously in an east-west direction. in the giurgeu mountains the mean annual temperature in the 20th c. has been 4 –6 °c, in the transylvanian basin 8–9 °c, west of the arad–oradea line it has been just above 10 °c, while southwest of the nadlac–szeged line it has been above 11 °c (csoma, 1975; andó, 2002). 70–80% of the water drained by the river is originating from precipitation (andó, 1993, 2002). still, there is no close relation between floods and the temporal distr ibution of precipitation (andó, 2002), as the greatest floods are initiated by the melting of snow, accumulating in the winter period. the spatial distribution of precipitation shows a great variation (fig. 3). at the source of the river annual values are around 600 mm, going downstream this amount can double on the western slopes of the gurghiu mountains,but reac hing the closed transylvanina basin it falls back to 600 mm again. it increases again in the region of the sebeş and retezat mountains. west of lipova preci pitation decreases continuously (csoma, 1975). fig. 2 an average hydrological year based on 50 year mean values (1950-2000) climate model simulations for the 21 st century predict a continuous, but uneven temperature rise, with the most intense increase occurring in the su mmer months in the carpathian basin. the change in total annual precipitation in the models is not signi ficant; however, the temporal distribution is expected to become more uneven: decreasing summer and increasing winter precipitation (bartholy et al. , 2008, szabó et al., 2011; csorba et al., 2012). climate simulations do also emphasize that extreme weather events may occur more frequently in the next cent ury. this will be especially true for drought periods which will be longer and more severe than before (szépszó et al., 2008). effect of climate change on the hydrological character of river maros, hungary – romania 51 methods climatic changes concerning the entire earth are best predicted by global numerical models. these incorporate the most important processes and relationships acting in and between the major elements of the earth system (atmosphere, oceans, continents, ice sheets, biosphere, society). the horizontal resolution of global models, however, is only around 100 km, which does not provide adequate information for performing smaller scale, regional analyses (szépszó and zsebeházi, 2011). for the investigation of smaller areas, such as the drainage basin of a river, regional climate models can be applied. the resolution of these is much better than that of global models, since input data are more detailed and smaller scale relationships can be considered. as a consequence, atmospheric processes and surface changes can be predicted more precisely for a given area (van der linden and mitchell, 2009; szabo et al., 2011). large, earth scale models, however determine the possible end values of the regional forecast (giorgi and bates, 1989; giorgi 1990). the projection of climate processes to the future includes several uncertainties. these are caused by the natural oscillation of the climatic system, the complicated relationships between environmental elements, the limitations concerning the resolution of input data and the hardly predictable social-economic processes (cubasch et al., 2001; hawkins and sutton, 2009). from among the factors above mankind can affect mostly social-economic processes, and most of all, these factors can significantly determine the rate of climate change. several regional climate models comprise the territory of the carpathian basin, these are the aladin, the remo, the precs and the regcm (szépszó et al., 2008). for the purposes of estimating future climatic processes on the maros catchment, the change of climatic parameters was calculated on the basis of the aladin (www.cnrm.meteo.fr/aladin) and the remo (www.remo-rcm.de) models, since these are based on the sres a1b scenario. these models assume a moderate increase in the emission of greenhouse gases and an average degree of global warming. concerning population numbers the a1b scenario assumes an increase till the middle of the century and a decrease later, besides, it foresees a fast economic growth, the quick spread of new and more efficient technologies and a balance between the use of fossil and renewable energy sources (nakicenovic and swart, 2000; ipcc 2007). the horizontal resolution of the applied model data is 0.22° (approximately 25 km). the climate projections were generated by the numerical modelling and climate dynamics division of the hungarian meteorological service. for making comparisons, temperature and precipitation data were investigated. expected changes were examined for those periods of the year which are the most important in terms of floods and low water periods. the models provide daily temperature and precipitation data for the 2021–2050 and the 2071–2100 periods. results are given as the difference from the daily average values of the 1961–1990 reference period in mm for precipitation and in °c for temperature. from the daily data series average values were calculated for the two future periods (2021-2050 and 2071-2100) for those months which are important in terms of the hydrology of river maros. values were calculated for the grid points, interpolation between points was made by using kriging. at present our aim was to demonstrate the tendency of changes, but later on the basis of these data further models can be generated in terms of runoff and water balance. fig. 3 yearly mean precipitation (1901-1940) on the maros catchment (csoma, 1975) 52 sipos et al. (2014) results compared to the reference values both models predict an average 1.3–1.4 °c temperature increase for the 2021– 2050 period in the winter months (fig. 4). however, in a longer perspective the models forecast somehow different values. according to the remo the rise of mean temperature can be as much as 3.9 °c for 2071–2100, which is a substantial increase. the aladin predicts a little lower increase, being around 2.1 °c (fig. 4, table 1). however, even if we take the more optimistic version a significant warming can be expected on the entire catchment. if we take a look at fig. 4, in the first modelling period temperature rise seems to be uniform on the catchment. however, later the eastern carpathian tributaries and the lowland section of the river can be more affected. concerning the entire catchment, average precipitation values calculated by the two models are very different. according to the aladin, practically no change can be expected, while the remo predicts a 22 mm increase for 2021–2050 and 34 mm for 2071–2100 (fig. 5, table 2). average values though hide some regional differences. both models agree that there can be a notable increase in precipitation on the eastern mountainous part of the catchment (giurgeu mountains), while only a slight increase (remo) or even a substantial decrease (aladin) can be expected in the west (fig. 5). based on the above, it seems well supported that due to general warming the average snow reserve will decrease on most of the sub-catchments. although, at higher altitudes in the eastern carpathians the snow/precipitation ratio might be higher as a matter of precipitation increase. the severity of flooding on these sub-catchments will mostly be determined by the intensity of snowmelt. table 1 average temperature change (°c) on the maros catchment remo aladin 20212050 20712100 20212050 20712100 decemberfebruary 1.4 3.9 1.3 2.1 may-june 1.1 2.4 1.5 3.1 july-august 1.4 5.0 3.0 5.5 septemberoctober 2.2 4.8 2.5 4.6 annual 1.4 3.8 2.02 3.55 march and april temperature has a significant effect on the start and intensity of snow melt and therefore the development of floods. based on the models, a general temperature increase can be expected (fig. fig. 4 model predictions of temperature change compared to the reference period effect of climate change on the hydrological character of river maros, hungary – romania 53 4, table 1). for the first period (2021–2050) an average 1.1–1.5 °c growth is suggested. by the second period (2071–2010) this value can be as much as 2.4 °c (remo) or 3.1 °c (aladin). warming up can be more intensive in the transylvanian basin and on the lowlands, however the eastern catchment can also face an approximately 1.0 °c later a 2.0 °c temper ature increase in the spring period during the 21st ce ntury (fig. 4, table 1). these changes suggest that in an average year early spring snowmelt can be faster in the upland catchment. this does not necessarily mean greater floods, because we have seen the total snow reserve can be slightly lower. nevertheless, the period of flood development will extend, and in years of higher winter precipitation the chance of the development of extreme floods can increase. based on previous observations, the second potential flood of the year can occur as a consequence of may and june rainfalls (andó, 2002). model predictions are ambiguous in this respect (fig. 5, table 2). according to average data calculated for the entire catchment, remo forecasts an insignificant change in early summer rainfall for the 2021–2050 period, and a substantial 50 mm decrease for 2071– 2100. on the other hand aladin predicts an appro ximately 30 mm increase for the first period and just a minor increase for the second (fig. 5, table 2). the pattern of change is also different. according to the aladin model, the most significant increase can be expected in the middle of the catchment. on the co ntrary remo heralds the most significant decrease also to this area (fig. 5). therefore, the direction of change in this case is highly uncertain. consequently, it is hard to tell whether the significance of early summer rain-fed floods will increase or decrease. if we take the average of the two models rather insignificant changes can be expected. table 2 average precipitation change (mm) on the maros catchment remo aladin 20212050 20712100 20212050 20712100 decemberfebruary 22.38 34 0.12 -5.5 may-june -3.5 -50.1 32.6 35.4 july-august -0.3 -55.3 -21.5 -55.6 septemberoctober 2.2 8.3 -2.8 -17.4 annual 2 -53 44 -20 as it was mentioned earlier, the low water per iod starts in july (boga and nováky, 1986). from august discharges can be as low as 50 m 3 /s. the fig. 5 model predictions of precipitation change compared to the reference period 54 sipos et al. (2014) volume of water arriving to the lowland sections is greatly determined by the intensity of evaporation on the catchment. of course, human interventions, such as water storage, can also be of great significance. in this respect july–august temperatures are very important. both models forecast an increase, being between 1.4 °c (remo) and 3.0 °c (aladin), for the first modelling period (2021–2050). concerning the second period (2071–2100) the increase can be even more significant, reaching 5.0 °c (remo) or 5.5 °c (aladin) (fig. 4, table 1). the expected temperature growth is fairly uniform on the catc hment, however, according to aladin, warming will mostly affect the gurghiu mountains and the lo wland areas, while remo predicts the most intensive increase on the middle part of the catchment. therefore, the spatial pattern for warming cannot be u nambiguously determined. in the meantime, there is a high chance for the decrease of summer precipit ation. regarding the average values for the entire catchment the aladin model forecasts a 20 mm decrease for 2021–2050, while according to the remo, catchment averages may not change. ho wever, both models agree that by 2071–2100 precipitation loss can be around 55 mm ( table 2), affecting mostly the middle part of the drainage basin. the decrease can be less intensive in the western slopes of the hargitha, giurgeu and gurghiu mountains (fig. 5). concerning the summer period, therefore, increasing evaporation and decreasing precipitation can be forecasted. this can lead to a significant reduction in average discharges, which may result an increasing water shortage during the low water per iod starting from july–august. based on previous observations (konecsny and bálint, 2007), usually the september–october period brings the lowest discharges on river maros (sometimes only 30–40 m 3 /s). if catchment scale average temperature change is considered the two models are in good agreement. for 2021–2050 both models forecast a temperature increase, being around 2 –3 °c, while between 2071–2100 average warming can be as much as 4–5 °c (fig. 4, table 1). concerning the spatial distribution of temperatures, warming might affect less the slopes of the apuseni mou ntains and the gurghiu mountains, but in the transy lvanian basin and the tarnava tableland temperature rise can be dramatic (fig. 4). precipitation change is less obvious on the basis of the models, and catc hment scale averages seem to stay more or less the same as the 1961–1990 reference values (table 2). the calculated few mm changes are insignificant and they are within the error of the prediction. the high correspondence of the two models suggests that there is going to be a significant war ming in the early autumn period. in the meantime a verage precipitation values will hardly change, which can finally result a more intensive water loss through evaporation. this can lead to the development of long drought periods along river maros. discussion although we have seen that in certain cases the two models do not reinforce each other, there are some clearly recognisable tendencies in terms of future climate. warming will be general both in spatial and temporal terms. however, lower lying closed areas, such as the transylvanian basin, can be more severely affected. it seems also clear that temperature rise will be the most significant in the summer–autumn period, though the remo model forecasts significantly warmer winters as well. in the meantime, changes in precipitation are harder to predict. what seems obvious though is that the late summer period will face a significant precipitation decrease on the basis of ave rage values. changes in other seasons are less unambiguous (table 3). table 3 precipitation change (%) compared to the reference period on the mountain section of the catchment remo aladin 20212050 20712100 20212050 20712100 decemberfebruary 21% 31% 0% -8% may-june -2% -26% 16% 17% july-august 0% -32% -12% -32% septemberoctober 2% 8% -3% -17% annual 0% -7% 6% -3% if annual mean values are considered, a signif icant 1.4 °c (remo) and 2.0 °c (aladin) temper ature increase can be predicted already for 2021 –2050. moreover, by 2071–2100 overall warming can be 3.6 °c (aladin) and 3.8 °c (remo) compared to the values of the 1961–1990 reference period. interestingly, annual precipitation values show a slight i ncrease for 2021–2050 in case of the aladin model, but for the 2071–2100 period both models forecast a significant, 20–50 mm decrease. taking into consideration that the average precipitation is between 600 – 1000 mm on the catchment, this means a 5–10% reduction in annual runoff. the decrease can be even more significant if increasing evaporation is accoun ted, but further modelling is necessary to explore these relationships. concerning the hydrological regime of the river we can expect a more uniform runoff during the wi nter, however, early spring snow melt can be more intensive. in the meantime early summer floods might be less significant (table 3). therefore, the frequency and average magnitude of floods will slightly decrease, however, if conditions are suitable (high wi nter precipitation and fast snowmelt) extreme floods can of course occur. although several climate -related studies emphasize the relevance of high-precipitation extremes (szépszó et al., 2008), these will be characteristic mostly on the western half of the carpathian basin (horányi et al., 2009). consequently, from a effect of climate change on the hydrological character of river maros, hungary – romania 55 climatic aspect the hazards and conflicts related to floods and flood protection will not increase significantly along the maros/mureş in the near future. on the other hand, results show that summer and autumn low water extremes may be more frequent, and severe water shortage may occur along the lower section of the river from time to time (table 3). moreover, as we have seen, total annual runoff will certainly decrease in the long run. according to konecsny (2010), there are already periods with significant water deficit, meaning that the discharge is lower than the statist ically determined average low water value. thus, the main problems and conflicts related to the changing regime of the river will be related primarily to low water events. conclusions calculations concerning the future climate of the maros/mureş catchment were outlined, and the tendency of expectable changes was assessed in this study concerning the hydrological regime of the river. due to increasing temperatures at winter the average snow reserve can decrease on several subcatchments. nevertheless, at higher altitudes greater reserves may develop, since models herald a slight increase in winter precipitation. spring snowmelt can be faster in the upland catchment, thus in years when winter precipitation is high the probability of extreme floods can increase. in general, however, the magnitude of floods is expected to decrease. based on the models, considerable changes in the volume of early summer rainfed floods are not expected. for the summer and early autumn period dramatically increasing temperature and decreasing precipitation can be forecasted. this can lead to a significant reduction in average discharges. on a catchment scale mean annual temperature is expected to increase by 1.4-2.0 °c and 3.6-3.8 °c in average by 2021–2050 and 2071–2100, respectively. mean annual precipitation presumably will only slightly change by the first modelling period, however, for 2071–2100 the models forecast a significant, 20–50 mm decrease. considering the above a 5–10% reduction can be expected in annual runoff, and the severity of droughts will certainly increase. consequently, the main problems and conflicts of the future will be related primarily to low water events. industrial, agricultural, ecological and recreational demands need to be harmonised as each of these will grow during 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(2005) established relationship between average radius (�̅� ) and depth (d) of potholes and expressed the relation as �̅� = 𝑘𝑑𝜀 . they considered the potholes as radially expanding cylinders and designed a growth-model on geometrical base. pelletier et al. (2014) also showed that pothole depth (d)increases in proportion to both the mean pothole radius (�̅�)and the diameter of the largest grinding stone episodically stored in potholes.they also modeled a limit of depth to mean radius ratio (γ) beyond which bed shear stress (τ) become too small for abrasive work atop floor of the pothole and designed formula of minimum water depth for development of pothole of given radius on given slope. yet numerous questions concerning discrete erosion phenomena remain unanswered (whipple, 2004). for example, how pothole size related to stream power? how vortex velocity within pothole varies with rising river velocity and increasing 𝑑 / �̅� ratio? with given stream flow velocity, how vortex velocity changes with increasing pothole depths? how long the positive feedback between growth of potholes and vortex velocity (allen, 1968; 1971; blumberg and curl, 1974; hancock et al., 1998) goes on? moreover, to entrain stones from bottom of pothole for episodic abrasion (and shaping of stones), rouse number must be less than 7.5 (julien, 1998) which increases with increasing 𝑑 / �̅� of a pothole and which in turn reduces the frequency and degree of abrasion by stones. so beyond 𝛾~2, largest stones remains relatively idle with rough and irregular shape. the fundamental properties of sediments are size, shape, mineralogical composition, surface texture, and orientation. sediment shape plays an important role in selective transportation of the particle. settlement velocity of a sediment particle is again controlled by size, shape, and density of the particle. thus the shape, along with size and density, shed light not only on the transportation history of the deposit, but also on the immediate conditions at the site of deposition (knighton, 1998). pebbles or boulders from various environment are examined by gregory and cullingford (1974), carroll (1951), carroll et al. (1950), plumlley (1948), allen (1949), krumbein (1940, 1941a, b), zingg (1935), luttig (1962), bluck (1969), tricart and schaeffer (1950), riviere and ville (1967), flemming (1964), lees (1964) and folk (1972). using roundness measurement, [(2r/l) × 100], gregory and cullingford (1974) distinguished between till and fluvioglacial material and found lateral variation in pebble shape in northwest yorkshire. carroll (1951) examined variation in shapes and roundness of pothole pebbles collected from valley of the waters, wentworth falls, in the blue mountains. experiment done by rayleigh (1942, 1944) reveals that spherical pebbles are scarce. pelletier et al. (2014) found relation between the largest grinding stones diameter and pothole depths. 10 das (2018) in western india, potholes at indrayani knick point are studied by sengupta and kale (2011), kale and gupta (2001) and kale and joshi (2004) and established evidence of formation of potholes in bedrock on human timescale. but shapes of grinding stones responsible for shaping those potholes are not examined. so present study illuminated size and shape of the largest grinding stone in potholes and its role in pothole growth. importance of grinding stones in pothole growth potholes grow as a result of combined erosion of walls and floors. efficacy of erosion phenomena (springer et al., 2005) determines differences in erosion rate of wall and floor of the potholes. all type of sediments sizes stored in potholes and involved in erosion is collectively called stones (gilbert, 1877). suspended load-size stones (largely coarse sands) abrade on wall and increase the aperture of potholes. bed load-size stones like cobbles and boulders (knighton, 1998) on the other hand works atop floor of potholes are called grinders (springer et al., 2005). grinders roll, skip or slide to abrade atop floor of potholes to maintain depths with proportionally increasing radii. springer at al. (2005) reported small potholes having slightly concave floor and larger potholes having slightly convex floor in the orange river bed insouth africa. by inference, large bed load-size grinders are absent in small hemispherical potholes. as a result, dominant wall erosion gives the potholes hemispherical shape. grinder on the other hand perceived as largely responsible for pothole growth (springer at al., 2005). it is also reported that depths of potholes grow faster than radius. and as suspended load-size sediment mainly impacts on wall, they have little contribution in deepening the potholes. rather, grinders working solely atop floors are largely responsible forpothole deepening. grinding stones are swept around pothole floors and lower part of pothole walls. centrifugal force applied on rotating grinders in persistent non-transient vortices abrade more along the circumference than center of the pothole floors. as a result, potholes with central boss (morgan, 1970) and convex floor (springer et al., 2005) are intuitively shaped by grinders’ erosion phenomena. it was observed in some larger potholes that radius at the bottom are larger than radius of aperture. this larger radius towards bottom is largely because of abrasive works of bed load-size grinding stones. present paper examines the largest grinder found in each of the pothole and its role in pothole growth. pelletier et al. (2014) observed that pothole depths increase in proportion to diameter of largest grinding stones episodically stored in potholes. therefore, it is inferred that with uniform flow velocity of stream above potholes, vortices velocity increases with increasing depths of potholes and thereby entrapping larger largest-grinder. largest grinding stone, if too large to move by vortex velocity within pothole, may protect the pothole floors from further erosion causing formation of central boss (morgan, 1970) and convex floor (springer et al., 2005). but efficacy of erosion phenomena by largest stone or its role in shaping potholes depends not only on its size but also on shape. for example, two stones having equal sizes and weights may require different vortices velocity to be entrained if their shapes are different. for abrasion, the stone episodically stored in the potholes is to be entrained and set under eddy type of motion. to entrain a particle of sediment of volume ‘v’ density ‘ρ’ and diameter ‘d’, the force f of flowing water applied on it must equals its submerged weight ws = g(ρs − ρf). and this can be expressed as: f = m × a (1) where m = mass of sediment, a = acceleration. f = m × v t [∵a = v/t, v= velocity of water flow in river, t=time] or f = v×d × v t [∵m = vd] or f = v ×d × v t (2) suppose velocity ‘v’ of river flow is constant. volume ‘v’ and density ‘ρs' of sediment are also constant. diameter ‘d’ of irregular shaped stones is under question because natural grinding stones are seldom spherical in shape. if long axis (l), intermediate axis (i) and short axis (s) of a stone (fig. 1) of volume ‘v’ varied, amount of force applied on it also changes. fig. 1 dimensions of the largest grinding stones in potholes. l: long axis (length), i: intermediate axis (width), s:short axis (height) drag force (charlton, 2008; knighton, 1998) applied depends on surface area (a) of the stones exposed to flow direction (fig. 2). if l, i and s are unequal, then in normal condition, the stones will rest on the river bed with largest surface area (l×i) contact. therefore if l and i are relatively small, the s will be relatively large causing higher force applied by flow of water on the stones and vice versa. force applied by given flow velocity 'v' on a surface area 'a= i×s' perpendicular to flow direction (although all the points of the surface of a natural grinding stone are not perpendicular to flow direction) was calculated as: 𝐹 = 𝜌𝐴𝑣2 (3) therefore, higher the surface area exposed to water flow, higher is the applied force to initiate entrainment of stones (fig. 2). according to figure 2 both the grinding stones a development of streambed potholes and the role of grinding stones 11 and b have same volume, density, mass and therefore equal frictional force against movement. but a is cubical and b is cuboidal in shape. river's uniform flow velocity ‘v’ shown by length of the blue arrows are applying force ‘f’ perpendicularly on surface area (i×s) facing flow direction. as surface area of stone a exposed to river velocity is greater than surface area of stone b exposed to river velocity, force applied on a is also greater than force applied on b. so critical velocity to entrain stone a is much less than critical velocity needed to entrain stone b. surface area exposed to direction of water flow directly depends upon shape of the stones. it is maximum for spherical stones and minimum for planner and acicular stones (zingg, 1935). fig. 2 different surface areas of the cubical (a) and cuboidal (b) shape grinding stones exposed to flow direction the shape of stones determines friction angle (fig. 3) of sediments which in turn determines force applied on it which in turn determines momentum of stones without which carving of pothole is impossible. therefore in equation (4), shape factor which is most appropriately represented by sphericity ψ was incorporated to find out critical force fc needed to set a stone in motion. as sphericity of all natural river borne stones are less than 1, it reduces surface area of stones perpendicular to flow direction and in turn reduces drag force applied on stone. 𝐹𝑐 = v×d × v 𝜓×t (4) if velocity ‘v’ of the river is known, and if we can derive eddy velocity 𝑣𝑒 within pothole with increasing aspect ratio γ (depth to width ratio) and once eddy velocity 𝑣𝑒 is known, one can logically guess (using hjulstrom's 1935 curve) about whether the largest boulder stored in the pothole have ever been entrained to abrade atop floors of pothole or it is lying inactively protecting the floors and giving it convex shape. fig. 3 stones shape and size control friction angle which in turn determines their entrainment velocity and critical shear stress (charlton, 2008) shear stress is regarded as the most important impelling force to set a sediment particle in motion. when critical shear stress τcr equals stones shear stressτ0, stone starts to move. it is defined as: τcr = k(ρs − ρf) × d × g (knighton, 1998) (5) where ρs = density of sediment, ρf = density of water, d = diameter of sediment= √𝐿 × 𝐼 × 𝑆 3 (williams, 1965) and g = acceleration due to gravity (9.81𝑚𝑠−2). putting the value of the given shields parameters (k = 0.045 (knighton, 1998) for pebbles and boulders) the equation (6) can be simplified as: τcr = k(ρs − ρf) × d × g (knighton, 1998) or, τcr = 0.045 (2700kgm −3 − 1000kgm−3) × d × 9.81𝑚𝑠 −2 [average density of dolerite/ granite 2700kgm-3] or, τcr = 0.045 (1700kgm −3) × d × 9.81𝑚𝑠 −2 or, τcr = 76.5kgm −3 × d × 9.81𝑚𝑠−2 or, τcr = 750.46d incorporating shape factor, the equation is given as: 𝜏𝑐𝑟 = 750.46 𝐷 𝜓 [𝐷 = √𝐿 × 𝐼 × 𝑆 3 ] (6) but submerged sediment weight is not only the resisting force to motion. degree of packing ‘ɳ’of sediment is of significant importance which in turn, to some extent, controlled by shape of stones (fig. 3). shape factor of sediment also exerts its direct influence on critical shear stress. τcr = ɳg(ρs − ρf) × π 6 × 𝐷 𝜓 × tan ф (7) where ɳ = a measure of grain packing, ф = friction angle. stones shape in pothole therefore is of great significance which determines not only chance and frequency of entrainment of largest stones under given maximum river velocity but also of the smaller stones of different size and shape. therefore, sizes and shapes of bed load-size grinding stones (and largest grinder) are given importance because those are [1] determinant of drag force needed to initiate stones motion needed to abrade the floors, [2] restrainer of critical shear stress to set a sediment particle in motion, [3] responsible for increase in potholes depths,[4] responsible for convexity of potholes floors and [5] responsible for overall pothole growth (springer at al., 2005). study area in our study potholes in the subarnarekha river bed downstream of bhatajhor river confluence at ghatsila were investigated. subarnarekha river has a total length of 395 km, covering a drainage area of 18,951 km2. after origin near nagri village in ranchi hill area at an elevation of 600 m (cwc, 2015), the subarnarekha river traverses through ranchi, seraikela, kharsawan and east singhbhum districts in the state of jharkhand, east india (fig. 4). thereafter, it flows through paschim medinipur district in west bengal for 83 kilometres and balasore district of odisha for 79 kilometers to join the bay of bengal near talsari. there is a small cluster of about 40 potholes in middle subarnarekha river bed at the immediate downstream of bhatajhor river confluence at ghatsila, a town of east https://en.wikipedia.org/wiki/ranchi_district https://en.wikipedia.org/wiki/seraikela_kharsawan_district https://en.wikipedia.org/wiki/seraikela_kharsawan_district https://en.wikipedia.org/wiki/east_singhbhum https://en.wikipedia.org/wiki/paschim_medinipur_district https://en.wikipedia.org/wiki/west_bengal https://en.wikipedia.org/wiki/balasore_district https://en.wikipedia.org/wiki/bay_of_bengal https://en.wikipedia.org/wiki/talsari 12 das (2018) singhbhum district of jharkhand in india. for this study, largest grinding stone was collected from each of 34 potholes from there (fig. 4). fig. 4 location of study area and the sampling site there is a vast variation in peak water level which varies from 378.9 m to 8.9 m. zero of the guage of the river subarnarekha at ghatshila was 72.00m and peak water level ever recorded was 85.05m recorded on 17.08.1974. discharge recorded on that day was 9579.59 cumecs. minimum water level 45.14m was recorded on 20.04.1972 when discharge was only 3.8 cumecs. highest discharge ever recorded was 10582 cumecs on 06.08.1997 and minimum discharge ever recorded was 0.4 cumecs on 12.03.2010. so there was a high seasonal and annual variation in guage height and discharge. average sediment load during monsoon months (2182000 metric tones) was 110 times higher than average sediment load during non-monsoon months (19800 metric tones). surface exposure of schist / phylite and quartzite of singhbhum group of rocks are recorded around ghatsila, a town of east singhbhum (fig. 5) district of jharkhand of india (gsi, 2006). foliated mica-schists forms the bed of the river subarnarekha. foliations of schists dip 50˚ 70˚ towards south and south-west. an arc of fault line eastnorth-west with doleritic intrusion runs across the river subarnarekha at study site. outcrop of doleritic dyke is aligned east-west across the river atop which potholes are sculpted. dolerite substrate are characterized by vertical cross joints and cracks which facilitated potholes formation. fig. 5 geological setup of the study area materials and methods first of all, 34 potholes (more than 80% of the population of the study site) were selected randomly. then those were numbered serially to avoid overlaping and gaping. then diameters and depths of potholes were recorded (fig. 6). potholes with collapsed walls were not selected because it made difficulty in measuring their dimensions. as materials for this study are data on different variables of largest grinding stone stored in potholes, long axis (l) intermediate axis (i) and short axis (s) of stone (fig. 1); volume, shape, weight, flatness and sphericity of largest grinding stone was recorded from each of the 34 potholes. weight was measured by electronic balances of 1.0g to 500.0g and 100.0g to 15000.0g. volumes were measured diping the stone into water and collecting the replaced water by stone in a graduated jar which gives volume of the stone directly. absorption of water by dry stone affects volume of replaced water. so dry stones were first dipped into water before puting it into water of measuring device. shape of stones are explained in terms of sphericity and flatness and measured using formulas of krumbein (1941 a,b) and cailleux (1945) respectively. sphericity (ψ) of the largest grinding stone was determined using the formula by krumbein (1941). higher the value ofψ, more spherical is the stone. ψ = √(𝐼𝑆/𝐿2) 3 (8) using ratio of intermediate axis (i) to long axis (l) and short axis (s) to intermediate axis (i) stones were classified (zingg, 1935) into different sphericity classes. cailleux (1945) developed the flatness index (𝔽) based upon the relationship between the particle dimensions along the three principal axes. the index is given by 𝔽 = 𝐿+𝐼 2𝑆 (9) theoretically, lowest value is 1.0, the higher the value more flat is the stone. the measure is opposite to the sphericity index. if sphericity of stones is greater, its development of streambed potholes and the role of grinding stones 13 flatness is less and vice versa. roughness of pothole stones is the degree of irregularities in shape. it has opposit notion of sphericity. roughness of stoness was measured using formula 𝑅 = 𝐿−𝑆 𝐿 . (10) fig. 6 a. pothole where depth is greater when comparing to aparture diameter. b. dimensions measured with the help of a specially devised instrument. c. weight measurement of grinding stones d. pothole almost full of stones quoted with mosses. out of the largest 34 grinding stones found in 34 potholes, the largest (amongst the 34 largests) was of diameter 19.89 cm. the stone was rounded and logically assumed that it was entrained by river velocity and was in abrasive action for pothole growth. entrainment velocity (1.5 m−s) for that largest stone was taken from hjulstrom's curve (1935). then forces applied by that given velocity 'v' (v = velocity 1.5 m−s needed to entrain largest d=19.89cm of the 34 grinding stones was derived from pjulstrom curve) on surface area 'a' (of all other grinding stones) perpendicular to flow direction (although all the points of the surface is not perpendicular) was calculated using equation no. 3. results and discussion potholes depths of potholes were from 17cm to 147cm. average depth was 55.32cm and coefficient of variation of depth was 56.08. out of 34 potholes, 16 potholes had depths less than 0.5 meters and rest 18 potholes had depths from 0.5 meters to 1.47 meters. volume of potholes were from 0.005m3 to 1.672m3. average volume of 34 potholes was 0.22 m3. median volume was found 0.081m3. 30 potholes had volume less than 0.5 m3 and only 4 potholes had volume above 0.5m3. only one pothole had its volume more than 1.0 m3 and it was 1.672m3. size, weight and shape of largest stones average size (volume) of 34 grinding stones is 1991.28 cm3. the largest one is of 7873.60 cm3 and the smallest one is of 83.64 cm3. the greatest weight of stones (12096 g) does not correspond to the largest size of stone. lowest weight of stones was recorded 83.3 g and average weight was 2950.48 g. there is a very strong correlation (r² = 0.94) between stones size and stones weight which indicates homogeneity of stones composition. there are two distinct clusters of stones (fig. 6): one group of relatively smaller size and light weight having compact association. perhaps these stones are working for a longer period within potholes and have got more sphericity (ψ = 0.66 to 0.88) in shape. another group of five stones of larger size and heavy weight have relatively dispersed association. this is because larger stones may be the collapsed blocks of the pothole wall and have not experienced long abrasive action to be spherical (ψ = 0.46 to 0.62). moreover, the larger five stones were of varying parent rocks (dolerite-1, quartzite-2, schist-1, granite-1). sphericity (ψ) indicates how long the stone was involved in pothole formation. longer period the stone is engaged in abrasion of pothols, the stone is more spherical. sphericity of stones ranges from 0.46 to 0.88. most irregular stones with low sphericity were found in breached potholes (richardson and carling, 2005). out of 34 grinding stones, 38.24% stones were found to be oblate shaped (fig. 8), 26.47% stones were recorded as spherical while 23.53% and 11.76% were prolate and blade shaped respectively. standerd deviation (sd) of ψ of 34 stones was 0.08 and coefficient of variation (cv) was 11.28 %. these imply that there was no significant variation in shape of the largest grinding stones of 34 potholes. fig.7 relationship between stone size and weight: stone size and weight shows a strong correlation with a distinct variation between two clusters roughness varied from 0.78 to 0.17. average roughness of stones was 0.50. out of total, 25 % of observation have roughness less than 0.45. half of the observations have roughness value less than 0.52 and 75% of the distribution have roughness value less than 0.55. out of 34 grinding stones, 14 stones had roughness of <0.5 and rest 20 stones had roughness >0.5. flatness and roughness of stones came from original shape of the clast and differential rate of abrasion. but long grinding reduced flatness of stones. highest and lowest flatness were found 3.36 and 1.10 respectively with an average of 1.81. sphericity (ψ) and flatness (𝔽) are opposit consideration about stones shape (fig. 9) and finding of present study illuminate relation between them which is expressed as 𝔽 = 0.989ψ-1.59 (𝑅2 = 0.78). y = 1.6125x 290.59 r² = 0.9396 -2000 0 2000 4000 6000 8000 10000 12000 14000 0 2000 4000 6000 8000 10000 s to n e w e ig h t (g ) stone size (cm3) 14 das (2018) sphericity and flatness of grinding stones are inversely related to each other. more flat the stone less force is applied on it when velocity is constant. fig. 8 classification of the largest stones according to their sphericity (after zingg, 1935) fig. 9 relationship between sphericity and flatness of grinding stones (a), relationship between flatness and the applied force by velocity (b) controls on stones shape it was found that with increasing depth/radius ratio (γ ) of pothole, sphericity of stones increased. it means that potholes with more depth were associated with more smoother or spherical stones. it happened because episodically entrained stones entrapped in potholes abrade atop floors years after years to increase γ . as a result gradually they became spherical. but bottom shear stress (τb) decreased rapidly beyond depth/radius ratio 𝛾~2. stones size and shape control amount of force (f) to be applied on them by moving water. it was found that larger the grinding stone more was the force applied on it (𝑅2 = 0.98) and vice versa (fig. 10a). forces applied on stones are proportional to sphericity (ψ) and expressed in power relation as 𝐹 = 0.59𝜓3.25. on the contrary, higher the flatness lower was the forces applied on stones (fig. 10b). fig. 10 relationship between the force applied on a grinding stones and (a) size and (b) sphericity flow depth is also important for the process of abrasion work by stones and growth of a pothole and shapes of stones itself. with given channel slope (e.g. ̴ 10-1 m/m) flow depth required for the growth of a pothole is approximately equal to the diameter of the pothole (pelletier et al., 2014). data for this study were collected from 34 potholes not within bed of the river in true sense but atop a wide doleritic dyke (well above the river bed). that is why, frequency of necessary flow depth for 𝔽 = 0.989ψ-1.59 r² = 0.781 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.4 0.6 0.8 1.0 f la tn e ss ( 𝔽 ) sphericity (ψ) a f = 0.41 𝔽 -1. 45 r² = 0.179 0 10 20 30 40 50 60 70 0 1 2 3 4 f o rc e a p p li e d b y v e lo c it y 1 .5 m /s e c o n g ri n d in g s to n e s (n e w to n ) flatness (𝔽) b f = 0.001d 2. 14 r² = 0.98 0 10 20 30 40 50 60 70 80 0 10 20 30 f o rc e a p p li e d b y v e lo c it y 1 .5 m /s e c o n g ri n d in g t o o ls ( n e w to n ) diameter of grinding stones (cm) a f = 0.59 ψ 3. 25 r² = 0.27 0 10 20 30 40 50 60 70 0.4 0.6 0.8 1.0 f o rc e a p p li e d b y v e lo c it y 1 . 5 m /s e c o n g ri n d in g s to n e s (n e w to n ) ψ b development of streambed potholes and the role of grinding stones 15 pothole growth is annual when the dyke is over topped by the peak flow of rainy season. moreover, galudih barrage (completed in 1954) at 12.9 km upstream diverts a considerable share of the flow through irrigation canal. as a result discharge can not overflow onto normally dry doleritic dyke and stones in potholes remains idle for years to gather moss on them (fig. 6d). the largest grinding stone and potholes growth 𝑇ℎ𝑒 𝑅2between potholes size and stones size was much less (0.17) than 𝑅2 between potholes size and stones weight (0.25). yet, larger the pothole, larger and heavier was the largest grinding stone (fig. 11). but present study does not confirm the finding of pelletier et al. (2014) that 'pothole depths increase in proportion to the diameter of the largest clasts episodically stored in potholes’. fig. 11 relationship between diameter of largest grinding stone and the size of potholes absence of convex floor in all potholes indicate the active role of largest grinding stone which abrade atop floor instead of protecting it. so sufficient eddy velocity was there to entrain the largest stones and abrade atop potholes floor. considering stream velocity 1.5m-s needed for entrainment of the grinding stone of diameter 19.89cm (largest among 34 stones), forces applied on grinding stones were calculated using equation (3). average force applied on stone was 23.02 n (newtons) with sd 15.65 avd cv 67.96%. low variation in ψ and higher variation in applied force indicate that size of the largest stone is not proportional to pothole depths. conclusion grinding stones in potholes are important component of channel incision, as the largest grinding stone has significant control on pothole growth. largest grinding stone made all the pothole floors concave by abrading atop it. the largest grinders found in potholes cluster of same locality were of same composition which was expressed in strong correlation between stone’s size and weight. diversion of flow by artificial efforts reduced discharge through channel and interfered adversely the natural fluvial environment. grinding stones in potholes were left idle and mosses gathered on those unrolling stones. very few grinding stones in potholes are spherical in shape. drag force applied on the largest grinding stone and their entrainment velocity depends considerably upon their shapes. therefore, to have an insight into the hydraulics and processes operating within potholes, size and shape of largest grinding stone may be considered as an instrument. this new insight into pothole dynamics will enable better understanding process-form feedbacks in bedrock channel. acknowledgement i deeply acknowledge my gratitude to my students of m.sc. 3rd semester with special paper fluvial geomorphology (session 2014-16) who did laborious job of data collection on pothole stones. references allen, p. 1949. wealden petrology: the top ashdown pebble beds and the top ashdown sandstone. quarterly journal of the geological society 104 (1-4), 257–321. doi: 10.1144/gsl.jgs.1948.104.01-04.12 allen, j. r. l. 1968. on criteria for the continuance of flute marks, and their implications. geol. mijnbouw 47, 3–16. allen, j. r. l. 1971 transverse erosional marks of mud and rock: their physical basis and geological significance. sediment. geol. 5, 165– 385. doi: 10.1016/0037-0738(71)90001-7 bluck, b.j. 1969. particle rounding in beach gravels. geological magazine 106, 1--14. doi: 10.1017/s0016756800051682 blumberg, p. g., curl, r. l. 1974. experimental and theoretical studies of dissolution roughness. journal of fluid mechanics 65, 735– 751. doi: 10.1017/s0022112074001625 carroll, d. 1951. pebbles from a pothole: a study in shape and roundness. journal of sedimentary petrology 21 (4), 205–212. doi: 10.1306/d4269481-2b26-11d7-8648000102c1865d carroll, d., brewer, r., harley, j.e. 1950. pebbles from the upper hunter river valley. n.s.w.. journal and proceedings of the royal society of new south wales 83, 2515–262. cailleux, a. 1945. distinction des galets marins et fluviatiles. societe geologique de france bulletin 15, 375–404. charlton, r. 2008. fundamentals of fluvial geomorphology, isbn 0203-37108-9, routledge, new york, ny 10016, p-43 curl, r. l. 1974. deducing flow velocity in cave conduits from scallops. nss bull. 36(2), 1–5. cwc, 2015. hydrological data directorate information system organisation, water planning & projects wing, central water commission, govt. of india, new delhi, p 6. flemming, n.c. 1964. form and function of sedimentary particles. j. sediment. petrol. 35, 381–390. doi: 10.1306/74d71280-2b2111d7-8648000102c1865d folk, r. l. 1972. experimental error in pebble roundness by the modified wenteorth method. j. sediment petrol. 35, 381–390. doi: 10.1306/74d7269e-2b21-11d7-8648000102c1865d gilbert, g. k. 1877. report on the geology of the henry mountains: geographical and geological survey of the rocky mountain region. gov. print. off., washington, d. c.106 p. gregory, k. j.,,cullingford, r.a. 1974. lateral variations in pebble shape in northwest yorkshire. sedimentary geology 12 237– 248. doi: 10.1016/0037-0738(74)90020-7 gsi, 2006. district resource map, east singhbhum, jharkhand, geological survey of india (gsi), kolkata, govt. of india hancock, g.s., anderson, r.s., whipple, k.x., 1998. beyond power: bedrock river process and form. in: tinkler, k.j.,wohl, e.e. 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392, isbn 0-8137-2392-2 riviere, a., ville, p. 1967. sur l'utilisation d'une indice morphologique nouveau dans la representation d'une formation detritique grossiere. c.r. acad sci. paris, ser. d; 1369--1372. sengupta, s., kale, v. s. 2011. evaluation of the role of rock properties in the development of potholes: a case study of the indrayani knickpoint, maharashtra, j. earth syst. sci. 120 (1), 157–165. doi: 10.1007/s12040-011-0005-5 springer, g. s., tooth, s., wohl, e. e. 2005. dynamics of pothole growth as defined by field data and geometrical description j. geophys. res. 110, f04010, doi: 10.1029/2005jf000321 tricart, j., schaeffer, r. 1950. l'indice d'emoussee des galets. rev. geomorphol. dyn. 1, 151–179. whipple, k. x. 2004. bedrock rivers and the geomorphology of active orogens. annu. rev. earth planet. sci. 32, 151– 185. doi: 10.1146/annurev.earth.32.101802.120356 whipple, k. x., hancock, g.s., anderson, r.s. 2000. river incision into bedrock: mechanics and relative efficacy of plucking, abrasion and cavitation. geological society of america bulletin 112, 490–503. doi: 10.1130/00167606(2000)112<490:riibma>2.0.co;2 williams, e. m. 1965. a method of indicating pebble shape with one parameter, journal of sedimentary petrology 35, 993–996. doi: 10.1306/74d713ed-2b21-11d7-8648000102c1865d zingg, t. j .1935. beitrag zur schotteraaalyse: schweiz. min. pet. mitt 15, 39–140. introduction importance of grinding stones in pothole growth study area materials and methods results and discussion potholes size, weight and shape of largest stones controls on stones shape the largest grinding stone and potholes growth conclusion acknowledgement references journal of environmental geography journal of environmental geography 6 (1–2), 37–47. doi: 10.2478/v10326-012-0005-1 issn: 2060-467x assessing landscape sensitivity based on fragmentation caused by the artificial barriers in hungary teodóra bata*, gábor mezősi department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: batateodora@gmail.com research article, received 31 january 2013, published online 15 april 2013 abstract artificial barriers significantly disturb the landscape unit. roads split the contiguous landscape units, thus basically modi fying their ecological characters. the more artificial barriers are constructed in the landscape, the more fragmented it is. theref ore, the contiguous landscape unit is divided into two or more patches, weakening resilience and stability of ecological syste ms. during decrease in patch size, the stability reduces until the patch size is at its minimum viable or effective population size. in current study analysing the degree of fragmentation caused by artificial barriers in meso -scale landscape units (meso-regions) we can get an overall picture about changes in their stability and sensitivity. the major aims of this study is to investigate the fragm entation of landscape units caused by three types of artificial barriers (roads, railways and settlements) in mic ro-regions, and to measure the degree of fragmentation and its spatial-temporal (1990, 2011 and future scenario to 2027) changes using mathemat ical/statistical analysis and landscape metrics (nu mber of patches, division, landscape splitting index and effective mesh size). by calculating landscape fragmentation metrics, the micro -regions are identified, which must be protected with high priority in the future. in the planning processes, type and position of artificial barriers could be more properly determin ed by calculation of these landscape metrics. keywords: landscape fragmentation, sensitivity, stability, artificial barriers, landscape metrics introduction landscape pattern embedded in the matrix is formed by patches and corridors (forman and godron, 1986; formann, 1995). ecological barriers as linear elements delimit landscape patches of similar ecological characters. barriers can be categorized into natural (e.g. river -corridor) and artificial ones from the viewpoint of living being (kerényi, 2007). artificial barriers (e.g. roads, railways, settlements) can significantly disturb the landscape unit. roads and railways split the contiguous landscape units, thus basically modifying their ecological characters (forman and alexander, 1995; trombulak and frissell, 2000; forman et al., 2003). they can result completely isolated patches, altering the ecological interactions between natural habitats (harris 1984; sauders et al., 1991; forman, 1995). due to fragmentation the ecological stability d eteriorates and the natural material and energy flow can be affected (csorba 2005; moser et al., 2007). owing to the transport infrastructure (e.g. roads, railways) high concentration of pollutants is also emitted into the atmosphere, yielding change in micro-climate (saunders et al., 1991; reck and kaule, 1993; tro mbulak and frissell, 2000; spellerberg, 2002; jaeger, 2002; forman et al., 2003). the more than 20 m wide motorways exert significant influence on run-off and groundwater flow (barta and szatmári, 2010; barta et al., 2011; kun et al., 2012). consequently, in the highly developed countries the fragmentation is co nsidered as the most serious threat by which natural habitat is damaged (jongman, 1995; wascher and jongman, 2000). the more artificial barriers are co nstructed in the landscape, the more fragmented it is. therefore, the contiguous landscape unit is divided into two or more patches, weakening resilience and stability of ecological systems. during decrease in patch size, the stability reduces until the patch size is at its minimum viable or effective population size (size of isolated population which can survive with a given probability beyond a given period) (gilpin and soul, 1986). with the landscape fragmentation, the border length of landscape units increases, causing higher landscape sensitivity (mas et al., 2010). analysing the degree of fragmentation caused by artificial barriers in meso-scale landscape units (mesoregion) we can get an overall picture about changes in 38 bata and mezősi (2013) their stability and sensitivity. in the light of all this information, the major aims of this study can be summed up as follows: (1) to investigate the fragmentation of landscape units caused by artificial barriers in microregions, (2) to measure the degree of fragmentation and its spatial-temporal changes by mathematical/statistical analysis and landscape metrics. data and methods the investigations of micro-regions were carried out on the whole territory of hungary (marosi and somogyi, 1990 (fig. 1). data change in the degree of fragmentation caused by artificial barriers was analysed based on time series data: between 1990 and 2010, future scenario was calculated to 2027. types of artificial barriers investigated in current study are the following:  road network (motorways, highways, side roads)  railway network  borderline of inner-city area during the fragmentation investigation, railways and roads were regarded as not only linear but average 2dimensional elements (like 2-dimensional shape of settlements) (fi et al., 2012; megyeri, 1997) the average width of which are as follows:  motorway = 26.6 m  highway = 7 m  side road = 3 m  railway = 6.05 m similar to the settlements, these landscape elements, which cover an area determined by multiplying their width by length, represent “blind spot” for the natural wildlife. for example, 4.6 km 2 area of danube-tisza interfluve is occupied by the m5 motorway between budapest and szeged (173 km) without entry and exit slip roads (173 km x 26.6 m). therefore, the material and energy flow is the most mod ified in these areas, especially in their buffer zones.  data of 1990 as base year were originated from otab (1990) database on roads, railways and settlements.  data were available from gis maps of térkép ltd. (1:100000) (térkép ltd., 2011) to evaluate the fragmentation in 2011. for future scenario, county maps of the documentation „the long-term plans for development in hungarian motorways and highways” (1222/2011.vi.29. governmental regulation) were applied (vi.29. governmental regulation). after the geo-referencing process, planned tracks on the maps until 2027 were digitized and finally digitized tracks were joined to the integrated network database (see below) (fig. 2). by comparing road network maps of databases established at different times, they proved not to be coherent; thereby most road sections that already existed in 1990 are not properly jointed to those in 2011. besides, similar problem arose in the case of settlement networks, as well. all this can be explained with the absence of an integrated database containing the borderlines of inner-city areas in 1990 and 2011. during comparison of different databases, elimination of spatial inaccuracy is not easy. if we compare the sizes and locations of settlements in the studied period, territorial expansions can not always be attri buted to urban sprawl. fig. 1 micro-regions of hungary according to landscape delimitation in 1990 assessing landscape sensitivity based on fragmentation caused by the artificial barriers in hungary 39 these spatial errors may exert positive or negative influence on the fragmentation. in order to eliminate content inaccuracies an integrated road network database (based on network in 2011) was created in which the tables of attributes indicate road sections constructed prior to 1990 and between 1990 and 2011, respectively. with the help of this method, the error threshold has to be calculated exclusively in the case of settlements. during the tests, this value is 24.63 ha, which was counted as the average of size differences of settlements in two different basic databases . methods the degree of fragmentation caused by artificial barriers can be measured in terms of various landscape metrics (mcgarigal and marks, 1995; riitters et al., 1995; hainesyoung and chopping, 1996; hargis et al., 1998; jaeger, 2000). jaeger (2002) compared twenty-two landscape metrics to each other in order to find the most suitable one for fragmentation measurement. effective mesh sizecut (meshcut) proved to be the most adequate index. in addition, we counted three more metrics (number of patches, division, landscape splitting index), which indicate the degree of fragmentation in different units. in each case, the metrics were calculated at class level; thus the patches and the classes are landscape units fragmented by artificial barriers as well as medium-scale landscape ecology units (~ micro-regions), respectively. the degree of fragmentation caused by artificial barriers can be measured in terms of various landscape metrics (mcgarigal and marks, 1995; riitters et al., 1995; haines-young and chopping, 1996; hargis et al., 1998; jaeger, 2000). jaeger (2002) compared twentytwo landscape metrics to each other in order to find the most suitable one for fragmentation measurement. effective mesh sizecut (meshcut) proved to be the most adequate index. in addition, we counted three more metrics (number of patches, division, landscape splitting index), which indicate the degree of fragmentation in different units. in each case, the metrics were calculated at class level; thus the patches and the classes are landscape units fragmented by artificial barriers as well as medium-scale landscape ecology units (~ micro-regions), respectively. definition of landscape metrics indicating fragmentation:  number of patches (np): expresses the number of landscape units fragmented by artificial barriers. unit: pieces (mcgarigal and marks, 1995).  division (d): is defined as probability that two randomly chosen living beings can not meet in the study area. unit: % (jaeger, 2000).            n i t i a a d 1 2 1 where n: number of patches, ai: size of n patches, at: total area of the region.  landscape splitting index (s): is determined as the number of patches one gets when dividing the total landscape into patches of equal size in such a way that this new configuration leads to the same degree of landscape division as obtained for the observed cumulative area distribution. unit: piece (jaeger, 2000).    n n i t a a s 1 2 2 where n: number of patches, ai: size of n patches, at: total area of the region. fig. 2 map on the expansion of road network between 1990 and 2027 based on the integrated road network database 40 bata and mezősi (2013)  effective mesh size (meshcut): denotes the size of patches when the landscape is divided into s areas (each of the same size) with the same degree of landscape division as obtained for the observed cumulative area distribution. unit: ha or km 2    n i i t t cut a as a mesh 1 21 where n: number of patches, ai: size of n patches, at: total area of the region. with the help of gis data of térkép ltd. (2011) and otab (1990), maps of coordination center for transport development, these landscape metrics for each micro-region were calculated with respect to the railway, road network and settlements as artificial barriers for the year of 1990, 2011 and 2027. temporal changes in the fragmentation were also investigated in order to gain information on changes in landscape stability, sensitivity as well as potential landscape conditions in 2027 based on “the long-term plan and future development program of highway and motorway network” (1222/2011., vi.29. governmental regulation). in the case of change in meshcut index between 1990 and 2011 as well as probable further changes by the artificial barriers constructed in the microregion until 2027, these landscape units can be supposed to have already modified material and energy flows after establishment of the artificial barriers (fig. 3). in contrast, in the future the examined parameters will not more change, thereby generating landscape balance (van andel and aronson, 2006). fig. 3 potential ecosystem responses to disturbance (e.g. construction of artificial barriers) (van andel and aronson, 2006) results and discussion in order to get information on the sensitivity and the stability of landscape and its borders, temporal and spatial changes in fragmentation caused by artificial barriers (roads, railways, settlement) between 1990 and 2011 were determined calculating different landscape metrics. moreover, the effect of motorway and highway networks to be constructed until 2027 on the landscape was studied. the micro-regions were examined which can be negatively affected by artificial barriers, reducing their stability and increasing their sensitivity. changes in the artificial barriers between 1990 and 2011 almost 79% of the road network built between 1990 and 2011 is motorway (table 1), which covers the largest area of landscape compared to other two barrier types. furthermore, the entry and exit slip roads delimit landscape patches that have no ecological connectivity (~ residual patches) with each other or matrix (fig. 4). table 1 changes in the length of the road network between 1990 and 2011 sum length of track (km) 1990 sum length of track (km) 2011 change (km) motorway 953.99 3042.88 +2088.89 highway 6791.79 7234.60 +442.81 side road 53420.78 53535.45 +114.67 sum: 61166.34 63812.93 +2646.37 fig. 4 landscape components close to kiskunfélegyháza after the construction of entry and exit slip roads at the m5 motorway beside motorways, mostly highway bypasses were constructed around the settlements in the study period. these bypasses (fig. 5) are regarded to have the most significant fragmentation since their shapes can be not only straight but curved (their characters are similar to the entry and exit slip roads of motorways). connecting to an existing road (with both start and end points), they are constructed mainly outside borderline of the innercity area. therefore, they are more likely to delimit a part of the landscape than a long straight road. at the time of study period (1990-2011) hungarian railway network are not extended by new tracks, whereas the existing ones are modernized as well as new stations are also built (development of railway tracks, 2011). therefore, this type of artificial barriers has not assessing landscape sensitivity based on fragmentation caused by the artificial barriers in hungary 41 made the landscape more fragmented. despite the fact that railway transport was liquidated in some sections, these sections can act as artificial barriers. fig. 5 landscape components after the construction of bypass in szentes with regard to the error threshold, in the study period the most intensive territorial expansion was registered in the following hungarian settlements (in descending order): miskolc, érd, debrecen, győr and tiszaújváros. in addition, it was 12 cities in hungary that exceeded 10 km 2 in the study period. change in fragmentation of micro-regions due to artificial barriers between 1990 and 2011 s, d, meshcut metrics, except for np, have been developed over the past decades (jaeger, 2000; moser et al., 2007), providing additional information on fragmentation and sensitivity of landscape compared to conventional metrics (jaeger, 2002). np is the most common index of fragmentation. in the years 1990-2011, change in np index was not determined in the case of 105 micro-regions, whereas this index increased in the case of 92 micro-regions. in terms of this index, fragmentation is the most considerable in the following micro-regions (in descending order): pest plain (+99) (fig. 6, no. 1), tolnai sárköz (+66) (fig. 6, no. 2) middle mezőföld (+64) (fig. 6, no. 3), sajó-hernád plain (+52) (fig. 6, no. 4), south baranya hill (+45) (fig. 6, no. 5). after the establishment of a new linear element in transport network, this element can cross the existing ones in the landscape, cutting a patch out of the original landscape unit. np unambiguously indicates this degree of fragmentation but can not give more information on characters of fragmentation and its adverse effects. as there has no been change in number of equal-sized patches defined with same probability, this index reflects no fragmentation in the case of 54 micro-regions (fig. 6). as far as s index is concerned, the five most fragmented micro-regions are: győr-tata terrace land (+12.33) (fig. 6, no. 6), middle nyírség (+9.4) (fig. 6, no. 7), sajó-hernád plain (+9.01) (fig. 6, no. 4), south baranya hill (+8.82) (fig. 6, no. 5), moson plain (+8.12) (fig. 6, no. 8). consequently, results of the s index are partially congruent with those of np index since sajóhernád plain and south baranya hill are the most fragmented micro-regions in terms of both metrics. fig.6 change in landscape splitting index (s) within micro-regions between 1990 and 2011 (based on fragmentation due to the artificial barriers ) 42 bata and mezősi (2013) the degree of fragmentation can be presented according to a specific example: in győr-tata terrace land (fig. 6, no. 6), np index was 11.74 and 24.07 in 1990 as well as 2011, respectively. therefore, nearly twofold increase in this value indicates very severe fragmentation caused by artificial barriers in this micro-region. in other words, due to nearly 10 km long m1 motorway section bypassing győr and urban sprawl of some cities (győr, tata, komárom), this micro-region needs to be subdivided into twice as many equal-sized patches in order that two living beings can meet within the study area. change in meshcut index during study period can be seen in the fig. 7 with special regard to error threshold, no change in meshcut can be noticed in the case of 54 micro-regions. considering effectively usable habitat, egerszegletenye hill (fig. 7, no. 1) can be considered to have the most unfavourable conditions (table 2). meshcut index reveals that this micro-region's total area of 645.02 km 2 decreased by 155.93 km 2 . owing to the highway 74, which cuts the micro-regions into two pieces in the north-eastern, and a section of the m7 motorway between nagykanizsa and letenye, np, s and d metrics have increased from 18 to 45, from 2.56 to 7.15 as well as from 61 to 86, respectively. therefore, the degree of fragmentation caused by artificial barriers is so serious here that the transport network development should be avoided in the future. if it is not possible, then road designers have to pay more attention to the ecological corridors of suitable quality and wide (ecoducts), which in optimal case facilitate faunal and floral migration between artificial objects. meshcut index demonstrates that the territory of more two micro-regions has decreased by 100 km 2 (table 2). landscape elements fragmenting micro-region tolna sárköz (fig. 7, no. 2) are the followings: the m9 and m6 motorways cut this micro-region into two pieces in the east-west as well as the north-south direction, respectively. landscape elements fragmenting micro-region hortobágy (fig. 7, no. 3) are the following: a section of the m3 motorway between polgár and hajdúnánás (55 km); the highway 35 towards hajdúböszörmény connecting to the motorway in the middle of the micro-region; a bypass situated in the eastern part of settlement polgár (fig. 8). table 2 landscape metrics of the three most fragmented microregions between 1990 and 2011 name of the micro-region change in np (pcs.) change in s (pcs.) change in d (%) change in meshcut (km 2 ) egerszegletenye hill (fig7. , no. 1) +27 +4.59 +25.08 -155.1 tolnai-sárköz (fig7. , no. 2) +62 +3.83 21.24 -133.74 hortobágy (fig7. , no. 3) +19 +1.54 6.15 -101.78 nevertheless, increase in the meshcut index can also be observed in the case of 24 micro-regions. the maximum and average of this increase are 247.79 km 2 as well as 75.23 km 2 , respectively. the first cause of increase in this index is the territorial expansion of settlements as a result of which they have reached the road network, in some case they have spread beyond it. therefore, the np and meshcut metrics have decreased and increased, respectively owing to the modified shape of habitats. the second and third causes of increase in the meshcut index are decrease in size of some settlements between fig. 7 change in meshcut index within micro-regions between 1990 and 2011 (based on fragmentation due to the artificial barriers) assessing landscape sensitivity based on fragmentation caused by the artificial barriers in hungary 43 1991 and 2011 as well as synergy of the first and second cases, respectively. it is unambiguous that reduction of the road and railways network is not responsible for the above-mentioned in the study period. consequently, further detailed studies are needed in the case of the concerned micro-regions in order to identify causes of this phenomenon. change in fragmentation of traditionally defined microregions due to artificial barrier between 2011 and 2027 if the long-term road development plan is fully implemented, 490.48 km more motorways (18.53%) and 2706.52 km more highways are to be constructed from 2011 till 2027. however, the plans have not included the construction of side roads (table 3). according to the scenario to 2027, np index will not increased, thus the fragmentation caused by artificial barriers can not be predicted in the case of 67 micro-regions. based on s index, fragmentation can not be assessed in 82 micro-regions, thus number of equal-sized patches, in such a way that this new configuration interprets to the same value of probability, will not increase. the following five micro-regions are likely to be the most fragmented in the future: northeast nyírség (+18.74) (fig. 9, no. 1), upper kemeneshát (+10.09) (fig. 9, no. 2), bácska loess plain (+9.68) (fig. 9, no. 3), hatvan plain (+7.87) (fig. 9, no. 4), szolnok túr plain (+7.12) (fig. 9, no. 5). table 3 changes in the length of road network between 2011 and 2027 sum length of track (km) 2011 sum length of track (km) 2027 change (km) motorway 3042.88 3533.36 + 490.48 highway 7234.60 9941.12 + 2706.52 side road 53535.45 53535.45 0 sum: 63812.93 67009.93 +2646.37 fig. 8 new roads causing fragmentation in hortobágy micro-region fig. 9 change in meshcut index within micro-between 2011 and 2027 (based on the fragmentation due to artificial barriers ) 44 bata and mezősi (2013) after implementation of the long-term road development plan, meshcut index of 101 micro-regions remain unchanged. in this aspect, dráva plain (fig. 9, no. 6) can be regarded as the most disadvantageous microregion in the future (fig. 9) since its total area (433.27 km 2 ) will decrease by mostly 100 km 2 (99.84 km 2 ) due to a highway to be constructed from sárvár to south border. this micro-region will be divided into two pieces in the north-south direction by new highway. therefore, d index will increase from 46.43 % to 70.85 %. in the case of three micro-regions, the meshcut index decreased by more than 100 km 2 over the period 19902011, whereas in 2027 based on scenarios lesser decrease can be predicted. however, the non-negligible fact is that four more micro-regions are supposed to suffer a reduction of more than 50 km 2 (table 4). in the future, we have to lay greater emphasis on landscape ecological study of these micro-regions if all the planned roads are built. as far as the sensitivity of microregions is concerned, the most optimal would be if road designers took notice of not only the location of conservation areas under “natura 2000” but reduction of landscape fragmentation for living beings based on calculation in current study. consequently, more detailed landscape studies are necessary in the concerned micro-regions. the sensitivity and stability of micro-regions fragmented by artificial barriers in accordance with above-mentioned, it is obvious how the landscape fragmentation was changed by artificial barriers in a historical period (1990-2011) and how it will be modified in the future (2011-2027) after longterm road plan implementation. so as to evaluate the sensitivity and stability of landscapes, two time-periods (1990-2027) were merged and analysed together. four groups of the micro-regions can be differentiated based on their meshcut metrics (table 5, fig. 10): 1. sensitive, mostly endangered, unstable microregions the fragmentation of which has changed in both periods. 2. potentially sensitive micro-regions the fragmentation of which did not change in the past, but they can be divided into smaller units due to the road development plans in the future. 3. potentially more stable micro-regions the fragmentation of which changed in the past, but they are assumed to have no further fragmentation after the road development implementation. 4. stable micro-regions with minor sensitivity the fragmentation of which did not change in the past and they are expected to have no fragmentation in the future. table 5 classification of micro-regions in hungary according to their sensitivity and stability group 1 group 2 group 3 group 4 number of micro-regions (pcs.) 129 15 46 40 sum area (km 2) 67588.8 5229.08 14381.8 5826.31 sum area (%) 72.66 5.62 15.46 6.26 1: in general, more than half of the micro-regions (129 of 230) have been divided into smaller units by artificial barriers in both study periods; they are most susceptible to external effects. habitats are shrinking due to landscape elements built relatively quickly; the different landscape damaging processes (e.g. new road constructions) have not completed yet, resulting more and more sensitive and unstable landscape. nonetheless, owing to data shortage the urban sprawl, which perhaps can reduce natural habitats, has not involved in current study. 2: 15 micro-regions were not fragmented by artificial barriers in the past, but they will be influenced in term of the road development plans up to 2027. average value and maximal decrease of the meshcut index are 3.3 km 2 as well as 11.7 km 2 , respectively. 3: 46 micro-regions are supposed to be more stable in the future since they are likely not to been fragmented (from optimistic aspect, if further road network expansion is not planned and there is be no urban growth). 4: 40 micro-regions can be considered to be in the most optimal conditions as they will not be divided into smaller units from 1990 to 2027. as a matter of fact, this is an optimistic viewpoint if no more road networks were planned and the urban sprawl was not more intense in the future. based on the test methods and data, these landscapes are in most stable conditions and are the least sensitive. this classification addresses that the units in groups „1”, and „2” must be protected with high priority. it is greatly recommended to minimize fragmentation in these micro-regions during the practical landscape planning. table 4 landscape metrics of the five most fragmented micro-regions between 2011 and 2027 name of the micro-region change in np (pcs.) change in s (pcs.) change in d (%) change in meshcut (km 2 ) dráva plain (fig 9., no. 6) +2 +1.56 +24.42 -99.84 szolnok floodplain (fig 9., no. 7) +12 +5.26 +14.43 -86.23 mohács island (fig 9., no. 8) +3 +1.47 +24.45 -85.41 western-inner-somogy (fig 9., no. 9) +9 +2.77 +10.01 -75.58 szatmári plain (fig 9., no. 10) +7 +7.07 +5.81 -59.99 assessing landscape sensitivity based on fragmentation caused by the artificial barriers in hungary 45 the landscape instability could be more effectively mitigated if not only the „natura 2000” areas were prioritized, but the above-mentioned landscape metrics were also taken into account during the road development planning. in the planning processes, type and position of artificial barriers could be more properly determined using the presented landscape metrics. moreover, suggestions could also be made about micro-regions the balance of which can not tolerate more external effects (girvetz et al., 2008; jaeger et al., 2007; fu et al., 2010). to realize all this, however, further analysis and various data are required. besides, the classification also calls for tasks to raise the stability and reduce the sensitivity in the case of micro-regions in groups „3” and „4”. more ecological corridors suitable for “green belts” should be designed so as to achieve these goals. conclusions the landscape is known to be a system in which the external effects can trigger instability and induce changes. the landscape sensitivity is interpreted as a rapid response to external effects, reflecting the conditional instability of the landscape system. the more artificial barriers are constructed, the greater fragmentation is, and thereby causing decrease in effective territory. as a matter of fact, there are a lot more artificial barriers in the landscape beyond examined ones, but present study aimed to investigate the artificial barriers, which can be rapidly constructed and have a most negative impact on the landscape. natural barriers could also be examined via the applied methods but artificial ones take more effect on landscape sensitivity thank to their “sudden” devastating impact in contrast to “slowly appearance” of natural ones. in this study, the spatial and temporal changes in fragmentation caused by artificial barriers were analysed so as to estimate the sensitivity and stability of the ecosystem and landscape units. the artificial barriers (e.g. roads, railways, settlements) can lead to extensive landscape modification. the contiguous landscape units are divided by roads and railways, thereby resulting profoundly transformation in their ecological processes. the ecological instability arises in the fragmented subunits and material and energy flow is modified owing to fragmentation. moreover, the contiguous landscape unit is divided into two or more patches, changing its ecological stability. different landscape metrics were calculated and together evaluated to determine the degree of fragmentation caused by artificial barriers (np, d, s, meshcut metrics). by comparing the degree of fragmentation in 1990 and in 2011, comprehensive view on the changes of landscape sensitivity are available now, whereas by involving data of long-term road development plan (up to 2027) into our research some scenarios can be demonstrated, as well. the presented examples also clearly show that study of the numbers and extension of artificial barriers, the np index has not provided enough information on fragmentation. if data from more periods are available, it is preferable to apply together three metrics (d, s, meshcut index), which express the degree of fragmentation by different units, thus providing more information on temporal change in landscape sensitivity and stability. fig. 10 classification of micro-regions based on their sensitivity and stability to artificial barriers using data of 1990, 2011 and 2027 46 bata and mezősi (2013) using meshcut index, traditionally defined landscape units were categorized into four groups according to their sensitivity and stability based on data between 1990 and 2011, as well as between 2011 and 2027. group 1 represents landscapes that are characterized by more sensitivity and a gradual loss in habitat stability due to the expansion of the artificial barriers. some landscape units (group 2) may only be sensitive in the future, others (group 3) may be heading for a more stable future and there are some landscapes (group 4) that were not and will not be affected by fragmentation caused by the artificial barriers. the advantage of the applied method is that landscape metrics are considerable help in choosing the location of artificial barriers. furthermore, it would be relevant to give some suggestion about landscape units the balance of which can not tolerate more such barriers. 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(vi.29.) governmental regulation. http://jogszabalykereso.mhk.hu/cgi_bin/njt_doc.cgi?doci d=138610.342073 (last available: 2013.02. 04) (in hungarian). http://www.nif.hu/hu/fejlesztesek/vasutvonalak/ http://epa.oszk.hu/02100/02154/00003/pdf/epa02154_rsgis_2012_01_14-38.pdf http://epa.oszk.hu/02100/02154/00003/pdf/epa02154_rsgis_2012_01_14-38.pdf http://www.hiszi-map.hu/index.php/terinformatika/ http://www.hiszi-map.hu/index.php/terinformatika/ landscape function analysis as a base of rural development strategies journal of environmental geography journal of environmental geography 10 (3–4), 17–26. doi: 10.1515/jengeo-2017-0009 issn: 2060-467x landscape function analysis as a base of rural development strategies krisztina filepné kovács1*, edina dancsokné fóris1, istván valánszki1 1department of landscape planning and regional development, szent istván university, villányi str 29-43, h-1118 budapest, hungary *corresponding author, e-mail: filepne.kovacs.krisztina@tajk.szie.hu research article, received 17 october 2017, accepted 5 december 2017 abstract research on ecosystem services and landscape functions are highly important in landscape ecology, landscape planning and open space design. the terms of ecosystem service and landscape function have been evolved parallel to each other in the scientific literature but have different focus. the term of landscape functions evolved from the scientific field of landscape ecology; it reflects the goods and services provided by regions, landscapes where the cultural, economic factors are important as well. as a framework assessment method with additional economic assessment, a landscape function analysis could be an additional tool of rural development, as it gives a complex analysis of multiple aspects, thus it is highly appropriate to explore, analyze the potentials, resources and limits of landscapes and land use systems. in the current research a landscape function analysis was compared with the rural development strategies in hungarian micro-regions. we focused on the level of landscape functions and the objectives of the rural development strategies of the study areas. the local development strategies do not focus on territorial differences nor potentials evolving from natural, cultural resources or local constrains. the only exception is tourism development, where in some cases there is a holistic spatial approach which intends to develop the region as a whole. keywords: landscape functions, rural development, micro-regions of csorna, pásztó, gönc introduction the terms of ecosystem services and landscape functions are very popular in landscape ecology research, landscape planning and open space design. since decades experts realized that the welfare of the society depend on the interactions with nature. the growing threat on our natural resources fostered researches on ecosystem services or landscape functions. the concepts of ecosystem services and landscape functions have similar meaning but different focus. these terms have been evolved parallel to each other in the literature. for the first time ehrlich and ehrilch (1981) used the term of ecosystem services and later costanza et al. (1997) dealt with the economic assessment of ecosystem services. the most important turning point was the publication of the results of the international research program millennium ecosystem assessment supported by the un, which remained the most comprehensive and complete program among those which have emerged in the field of ecosystem services (mea, 2005). the research program focused on the relation between social welfare and ecosystem services. those goods, services and spiritual, aesthetic values provided by nature as ecosystem services were considered which are used directly or indirectly by the human society (costanza et al., 1997; de groot et al, 2002). the landscape functions usually refer to the goods and services provided by regions, landscapes, when researchers analyze next to the environmental issues the infrastructural, cultural and economic characteristics of land use systems as well (bastian, 1997; hermann et. al,. 2004). schößer et al. (2010) compares the similaritie s and differences of the three concepts of ecosystem services. the goods and services provided by landscapes can be distinguished by different methods, but usually these values are divided into three major groups: production/economic, ecologic/environmental (cultural, aesthetic, educational etc.) goods and services. de groot and hein (2007) distinguished the carrier functions in the frames of production functions providing space and suitable substrate for settlements and cultivation. in the model of landscape functions brandt and vejre (2004) distinguished land use functions referring to material processes connected with land use. lamarque et al. (2011) highlights the fact that a clear demarcation between landscape functions and land use functions is not possible. what is the relation of landscape services and rural development? several researches focus on the multifuncinality of the landscape. the research of willemen et al (2010) underlined the trend that at multifunctional locations the total provided goods and services by the landscape were higher than at monofunctional sites and similarly de groot and braat (2012) explored the relation between land use intensity 18 filepné kovács et al. (2017) and the level of ecosystem services highlighting the fact that extensive land use systems provide wider range and higher level of services. several researches (mea, 2005; de groot and hein 2007; willemen et al., 2010; norgaard, 2010 etc.) have clearly defined the correlation between social welfare and ecosystem services/landscape functions, but especially in case of quality of life in rural areas we consider the wide range and complexity of landscape services extremely important. land use conflicts occur in such cases when a dominant land use /landscape function hinder the harmonious functioning of other functions mostly regulation, habitat or cultural functions. herman et al. (2014) emphasize the spatial analysis of landscape functions in order to reach well founded landscape development decisions. in spite of the vast research, mapping the term of landscape functions has not been introduced into the landscape management neither in practice of rural development (norgaard, 2010). but also norgaard is the one who reminds us for the most important shortages of ecosystem service analysis which is that they are simplifying the real circumstances and cannot consider the impacts of human activities. that is why it is extremely important to consider the complexity and synergies of our ecologic and social systems. in our research we focus on rural development because its focus is more the locality, local communities, ecology and landscape values, while regional development highlights the importance of economic, technologic development. the cork declaration emphasizes the multidisciplinary character of rural development and complex, integrated, multisectoral approaches and their local focus (ec, 1996.). the eu common agricultural policy and the former experiences collected in regional development form rural policy in hungary. because of the financial shortages the tools of the eu rural development policy are the most important determining factors in this field in hungary. the new hungary rural development programme forms the main priorities of agricultural and rural development. the rural development programs are realized mostly in the frames of leader program. the 96 local action groups try to mobilize local stakeholders and realize multisectoral development programs based on local strategies. the effectiveness of rural development depends on the depth of analysis of rural development strategies, whether the strategies consider the landscape conditions in reality, and react on the real values and conflicts. our research focused on the following objectives:  to analyze of the landscape-ecologic and economic characteristics of selected micro-regions through landscape function assessment method;  to compare the results of landscape function assessment and the rural development strategies of the study areas. study areas as study areas three rural micro-regions were allocated situated in different parts of hungary: micro-regions of csorna, pásztó and gönc (fig. 1). these micro-regions are part of the new administrative system elaborated in 2011, they are administrative units (group of 27-33 settlements) which in size are similar to the statistic units of lau1 level. all study areas are of rural character, of different landscape conditions and can be considered as peripheries. micro-region of csorna micro-region of csorna is situated in kisalföld, in region of western transdanubia which is the second most developed region of hungary (% of the eu-28 average, eu-28 = 100, central hungarian region 105,45; western transdanubian region – 74,53). but the development potential of csorna lags behind the neighboring regional centers (győr, sopron, mosonmagyaróvár). the micro-region consists mostly of villages of landscape of hanság and rábaköz. the settlement structure is characterized by small villages, 72% of the settlements have less than 1000 inhabitants, and just the center of the micro-region has slightly more than 10 000 inhabitants. rábaköz has been an intensively cultivated landscape since centuries while in the north because of the vast marshland of hanság large areas remained untouched. during 19th and 20th century drastic landscape changes took place because of the intensive drainage works. the remained moors, lakes, wet habitats, meadows of hanság are the most important ecologic values of the region. the river rába with its riparian forests mean a natural border in the south. the rábaköz rural development association holds the majority of the settlements together. micro-region of pásztó micro-region of pásztó is situated in county nógrád, at the feet of mountain mátra and the undulating landscape of cserhát, relatively far from the major transportation corridors and the busy cities. the region similarly to csorna can be considered as an inner periphery, characterized by small villages. its center, pásztó is located on the peripheries of the micro-region and the county, on the riverbanks of zagyva. the city of pásztó still in the medieval ages has been a busy cultural and economic center, transportation node but after the ottoman occupation it couldn’t regain its former significance. the fruit production, local vines, and the products of the water mills couldn’t compete with the industrialization of the neighboring cities. even the relocation of the major transportation corridors fostered this decline. the formerly important mines were closed. beside these negative processes the growing importance of tourism can be seen in the region. the diverse landscape resources, the ‘palóc’ the multifunctional agriculture, which represents a similar approach to landscape functions, highlights the social, cultural and ecologic role of agriculture as well (eec, 1992; ángyán and menyhért, 2004). in case of rural regions of extensive use and dominantly of natural land cover we can consider ecosystem services as landscape functions since the focus is here on goods and services provided by nature and self-sustaining processes (konkoly-gyuró, 2011). landscape function analysis as a base of rural development strategies 19 cultural heritage, the nature park of cserhát and geopark of nógrád provide the base for the tourism and economy of the region. the mountains of mátra and cserhát surround the region offering picturesque landscape scenery, the cultural heritage of the villages are mostly of local, regional significance (fig. 2). the majority of the settlements of the micro-region, with the exception of one single settlement belong to the cserhátalja local action group. micro-region of gönc micro-region of gönc is one of the most disadvantaged regions of hungary in spite of the rich natural and cultural values. the studied region is located along the slovakian border. from its 32 settlements two are towns (gönc and abaújszántó), 19 settlements have less than 1000 inhabitants. all the most important social and economic indicators show the unfavorable situation of the micro-region. in contrast, gönc is rich in cultural heritage as the remnants of the old settlement structure the hussite house in gönc, or the castle in boldogkő (fig. 3 a, c). the easternsouthern slovakian regional centre, košice with its 300 000 population has a remarkable influence on the neighboring hungarian areas as well especially after the opening of schengen boarders. the slovakian center is much closer to gönc than miskolc, the county seat. the recent connections have traditions since previously the region was called as “pantry of košice”. the settlement and infrastructure network of the micro-region have been formed by geographic conditions. the main transportation corridor of the region is stretching parallel to river hernád (road nr 3.). the majority of the smaller settlements are dead end villages. the abaúj leader association (local action group) holds 81 settlements together, and the majority of the micro-region of gönc. methods the conditions and differences in and among the study areas were explored by landscape function analysis using landscape indicators. our assessment is mostly based on data of the hungarian statistical office and the corine clc database 2012 and the system of teir (national information database of spatial planning). agricultural production and forestry, nature protection and habitat value based on naturalness, furthermore the cultural heritage were assessed. to investigate agricultural potential the ratio of arable land, ratio of fruit and grape plantations and forests were calculated. almost half of our country’s territory (48%) is arable land, thus we consider high intensity of cultivation in case the ratio of arable land is higher than 60 %, medium 40%-59% and low in case of lower values than 39% considering the ratio of arable land. to characterize habitat value, the ratio of natural/semi-natural land cover forms and the ratio of protected areas were considered. we assessed the ratio of natural or semi-natural corine land cover forms using the following corine clc types: land principally occupied by agriculture with significant areas of natural vegetation, natural grassland, moors and heathlands, sclerophyllous vegetation, transitional woodland scrub, broad-leaved forests, mixed forests, inland marshes, peat bogs, stream courses, water bodies. fig. 1 the location of the study areas, the micro-regions of csorna, pásztó and gönc 20 filepné kovács et al. (2017) to assess ecologic value, the ratio of protected areas was calculated. if we consider nature and landscape protection, there are several levels and types of protection in hungary. beside the nature protection categories (there are 10 national parks, 36 landscape protection areas, 147 nature conservation areas in hungary) there are natura 2000 areas (european union’s level of protection) and the national ecologic network. the national ecologic network represents the widest type of landscape protection in hungary, as this category is elaborated for spatial planning and includes all types of nature protection areas (natura 2000 and national park areas as well) and other officially not protected but all the ecologically valuable areas. the national ecologic network as a regulation zone is available in the national spatial plan and in all the master plans of the settlements. to avoid the duplication and overlapping of different protection types we focused our assessment on the national ecologic network. in the frames of the national ecologic network three categories are distinguished: core areas, buffer zones and ecologic corridors. the percentage values of naturalness and protected areas were divided by 10 to get a scale between 1 and 10 to help the multi-aspect comparison between the study areas. the evaluation of the beauty of the landscape is highly complex and sometimes because of its subjective judgment it is really difficult to find indicators. in order to avoid subjectivity, landscape beauty was related to naturalness (proportion of natural/semi-natural land cover forms) and as a weighing factor we considered the number and significance of cultural heritage/monuments based on the database of teir. the value of cultural heritage was calculated by the monument density per settlements and according to the significance we weighted the values. to get the final value of landscape aesthetics we summarized the values of naturalness and cultural heritage and calculated their average. we assessed touristic and recreational values (number of guest nights, commercial accommodations) using the database of the hungarian statistical office (2014). the data describing tourism potential varies on different scales, so to be able to summarize them and compare them on the level of settlements and micro-regions the data on a scale of 10 were projected and average value of data of number of guests and number of commercial accommodations were taken. the economic value and availability are important factors in the welfare of local inhabitants. to be able to compare the regions the data on a scale of 10 were projected. we evaluated the economic value by domestic income indicator (hungarian statistical office, 2015). in the second phase of our research project the objectives and tools of the rural development strategies of our study regions were analyzed. we assessed how the strategies reacted or were adjusted to the local levels of landscape functions or ecosystem services. results and discussion the landscape function analysis revealed the conflicts, limits of landscape resources and where certain landscape functions can be considered lower than the appropriate level. ecologic and habitat values there are large differences in micro-region csorna considering the ecologic values. we considered all types of nature protection areas including natura 2000, national park and the national ecologic network but to avoid duplication in the comparison analysis we focused on the national ecologic network. in the northern part of micro-region of csorna, in hanság high ratio of nature protection areas can be found. hanság is part of the national fig. 2 landscape and cultural values in micro-region pásztó (photos made by e. dancsokné fóris) a, the picturesque mountain line of cserhát; b, panorama of mátraszőlős with mountain mátra in the background; c, view of tar fig. 3 landscape and cultural values in micro-region gönc (photos made by i. valánszki) a, hussite house in gönc; b, panoramic view of river hernád; c, boldogkő castle landscape function analysis as a base of rural development strategies 21 park fertő-hanság, with natura 2000 and ramsar areas (proportion of natura 2000 areas: 54% tárnokréti, 36% barbacs, 33% maglóca, 33% csorna) meanwhile rábaköz consists of mostly intensively cultivated arable land (fig. 4) and landscape protection is represented just by the parts national ecologic network, mostly as pastures and the riparian forests along river rába. the lowest value among the study areas, 25% of the micro-region is part national ecologic network. fig.4 ratio of nature protection areas in settlements of microregion of csorna with two characteristic landscape parts of rábaköz and hanság, tóköz even micro-region of pásztó can be considered inhomogeneous but with higher ratio of landscape protection areas, 47% of its total area is part of the national ecologic network. the landscape protection area of eastern cserhát (eastern part) and landscape protection area mátra (northern part) are divided by intensive cultivated land and busy transportation corridors along river zagyva. there are a few settlements where almost the whole territory is part of the national ecologic network (felsőtold, garáb, cserhátszentiván). in micro-region of gönc landscape protection area of zemplén mountains with a wider zone of natura 2000 areas and protected areas along river hernád (almost 80% of the micro-region is designated natura 2000) are the most important nature protection areas. among the study areas here the total percentage of the national ecologic network is the highest: 80%. but the connection between the core areas is insufficient, missing. the proportion of natural and semi-natural land cover forms (naturalness values in fig. 5.) is in case of micro-region csorna the lowest 20%, in pásztó 46% and the highest value can be found in gönc micro-region 62%. landscape aesthetics landscape aesthetics was assessed based on the naturalness values and the number and significance of cultural heritage (database of national monuments teir database). if we consider the number of monuments (data base of teir) we find similar values in the study areas (microregion of csorna 66, micro-region of pásztó 58, microregion of gönc 57, the density is ap. the same 2 per settlements), but in csorna and pásztó with a few exceptions the cultural heritage is mostly of local significance. in micro-region csorna the most significant cultural value is the norbertine abbay. the villages are rich in architectural values but these are mostly of local significance. the indicators of landscape aesthetics reveal great differences in the micro-region. the majority of rábaköz (the southern part of the region) can be described as intensive arable land with large fields while hanság, tóköz are more diverse landscapes with higher proportion of natural vegetation or cultivated areas of lower intensity. as csorna is situated in a plain, the diversity of different land use forms is highly intensive from point of view of aesthetics, the large fields of rábaköz create a monotonous landscape. micro-region pásztó has rich, living palóc cultural heritage. the palóc cultural trail connects the cultural, architectural values of the villages. the remnants of the former mediaeval city of pásztó are still unknown for the greater public. dense network of tourist trails connects the natural values of nature park cserhát, landscape protection area of mátra and the geopark. hiking, eco-tourism and rural tourism are significant in the region. in micro-region of gönc the most important cultural and architectural values can be found in gönc, boldogkőváralja, vizsoly and tállya. the castle of boldogkő or regéc are remarkable landmarks with the fig. 5 ratio of natural, semi-natural land cover form based on corine land cover 2012 data 22 filepné kovács et al. (2017) natural environment creating a highly attractive scenery. there are several values of national importance as chuch of vizsoly, bible museum of gönc, castles of boldogkővár and regéc, wine production related heritage in tállya and abaújszántó. the traditional wine yards in the southern settlements which are part of world heritage site tokaj wine region represent also unique landscape values. values of less significance as rural churches, mansions can be found in all settlements. because of the differences in significance of the cultural heritage we tripled the value of micro-region of gönc (micro-region of csorna: 2,1; micro-region of pásztó 2,2; micro-region of gönc: 5,7). according to the summarized and average values of naturalness and cultural heritage gönc has outstanding values (micro-region of csorna: 2,3; micro-region of pásztó 3,4; micro-region of gönc: 7). agriculture and forestry in micro-region csorna agriculture is still an important base of the local economy, unfortunately the volume of the former flourishing vegetable and fruit production dropped below the national average since 1990. especially vegetable production was remarkable during the 1980’s and the 1990’s the cucumber was called as the “gold of rábaköz”. rather the arable land became dominant, especially in rábaköz the ratio of arable land is extremely high in several settlements (cakóháza 86%, egyed 84%, rábapordány 88%, rábacsanak 90%). the arable farming has less added value and lower need in labor force which reduces the population retention capacity of the villages. rábaköz can be characterized high, hanság low or medium intensity of agricultural production. forestry is not significant in the region the proportion of forests is just 9,5%. micro-region of pásztó is mostly covered by forests with higher ratio of arable land in the hilly landscape of the south. on the hillsides of favorable conditions after wine production was abandoned there is flourishing fruit production. pásztó micro-region has 32% forest cover. considering agricultural production two characteristic regions can be distinguished in gönc micro-region. the ratio of arable land is high in hernád valley, meanwhile in zemplén mountains the forests are dominant. the southern villages of the micro-region belong to the tokaj wine region historic cultural landscape, unesco world heritage site which still hold the traditions of worldwide famous wine production. in the vicinity of gönc fruit production is significant (apricot pálinka). forestry is an important economic sector; the average proportion of forests is higher than 40%. naturally there are great differences in the region, in the valley there are settlements with 4-4% and in the mountains some settlements have more than 80% forest cover. tourism and recreation tourism infrastructure is underdeveloped in csorna, recreational activities, with a few exceptions, are low in the region. the national park fertő-hanság offers a great potential but mostly the strictly protected areas of the national park (lake barbacs) belong to the micro-region which are not open to the public. mostly the centre, study trails and the programs organized by the national park are located around lake fertő with the exception of a few attraction (study trail hany istók, esterházy madárvárta). just in case of two settlements can we see considerable guest turnover (csorna 1502, farád 2226 guest nights spent in commercial accommodations in any other settlements none at all). looking at the data reflecting tourism potential micro-region of csorna has the lowest values with 3 807 total number of guests on the commercial accommodations and just 58 commercial accommodations (hungarian statistical office, 2014). the highest values describing tourism can be found in region of gönc with 14 860 total number of guests on the commercial accommodations and 851 commercial accommodations, although the recreational opportunities are extremely uneven in the micro-region. a few settlements do not have at all any tourism potential, meanwhile telkibánya, regéc (castle) are of national significance. telkibánya has the highest values in guest number at commercial accommodations (8387). the number of overnight stays per 1000 inhabitants is just slightly lower than the national average (2421). significant tourism types are: nature and rural tourism. micro-region of pásztó represents medium values among the study areas considering tourism potential with 4 787 total number of guests on the commercial accommodations and 308 commercial accommodations. in pásztó the open-air bath and the hiking trails are used mostly by locals and visitors from the neighboring villages in spite of the fact that the location between mátra and cserhát mountains offers great potential. the pilgrim route to the holy well of mátraverebély-szentkút crosses the region. the nearby old village of hollókő, world heritage site can be reached through cserhát greenway from the region. the palóc cultural trail and nature park cserhát have more potential. in spite of the existing potential the number of overnight stays per 1000 inhabitants (212) is just one tenth of the national average (hungarian statistical office, 2014). apart from szirák (3270 number of guests) just a few settlements have any commercial accommodations. accessibility major transportation corridors (m85, m86) cross micro-region of csorna. settlements along these corridors have great public transport accessibility, unfortunately the peripheral villages especially in southern rábaköz have really unfavorable accessibility. we can see similar dichotomy in micro-region of gönc. the southern and western settlements have proper availability. in zemplén mountains the transportation infrastructure is underdeveloped, there are several dead end villages. pásztó is located 80 km from budapest, but there are no direct public connection to the capitol, the villages have even worse availability. economic value according to figure 6 micro-region of csorna has the highest income values (927 376 ft) among the study regions, the average per capita domestic income is 30% higher than the amount of gönc micro-region. if we look behind the average values in all regions large differences landscape function analysis as a base of rural development strategies 23 can be found, especially in micro-region of csorna the northern-sothern division is remarkable. pásztó is situated east from the developed budapest agglomeration and north to the development line budapest-miskolc. the average per capita domestic income is in micro-region of pásztó 761 639 ft. gönc micro-region is one of the least developed areas of the country in 2012 the unemployment rate is 21,8 % (national average 9%), total income per capita 480 502 ft (national average 810 000 ft). comparing the studied regions (fig. 7) different levels of landscape functions can be seen. csorna is the most developed from economic point of view but here the lowest levels of landscape aesthetic, habitat values can be found. of course generalization hides the territorial differences: the most problematic is the southern part of rábaköz due to the intensive agriculture where it is crucial to develop the ecologic network by enhancing multifunctionality of agricultural production. the natural, cultural values are stable base for tourism and recreational development in gönc and pásztó micro-regions. from tourism attractiveness gönc has to be highlighted, where just the high differences in the level of tourism infrastructure hinders the effectiveness and profitability of tourism. landscape functions in rural development strategies the most important goal in rural regions according to the new hungary rural development programme (2014) are “enhancement of the population retention capacity… and improvement of the income generation capabilities”. the programme highlights the need for maintaining proper level of ecosystem services. the strategy states that the main functions of rural development policy are: 1. preservation and sustainable use of landscape, natural assets and resources, maintenance of ecosystem services. 2. processing and provisioning healthy and safe food. 3. enhancing economic development and quality of life and strengthening local communities in rural areas. the new hungary rural development programme mentions the term of ecosystems or ecosystem services 16 times. the strategy even highlights the importance of landscape management. regarding the local strategies the rural development programme of rábaköz leader group which holds together the majority of settlements of micro-region csorna formulates general framework of goals containing tourism development, enhancement of agricultural competitiveness. the strategy is not based on complex landscape assessment, the analysis focused on economic and social factors and description of the state of the environment (waste, sewage water, noise, water quality), in spite of the fact that the local stakeholders consider the most important potential of the region the tourism development based on natural values of hanság and thermal water. in case of the wider environment, the landscape is not considered the wish of a few villages to become rural tourism or eco-tourism destinations remains just a wish. diversification and enhancement of the ecologic value of the landscape require wide range of development projects, land use changes. however, the local strategy sets wide range of objectives even protection of natural values but unfortunately the focus is on business development, and the measures were reduced even further, containing only the support of organization of exhibitions, events (rábaköz rural development association, local development strategy 2014-2020) (table 1). fig. 6 net domestic income per inhabitant (ft) a, comparison between national average and the study areas; b, micro-region of csorna; c, micro-region of pásztó; d, micro-region of gönc 2015; source: www.teir.hu 24 filepné kovács et al. (2017) the local development strategy adopted by cserhátalja rural development association (micro-region pásztó) (hfs, 2016) sets wide range of objectives related to business development, small scale industrial development, tourism services, organization of events, strengthening local communities, preparatory documentation, safety investments, equal opportunities, low-waste issues, use of green energy (cserhátalja rural development association, local development strategy 2014-2020) (table 1). the local development strategy of abaúj leader group (micro-region gönc) among the general objectives as enhancement of economic development, quality of life, regional marketing, strengthening local communities, and education highlights the importance of tourism development, landscape management and diversification of agricultural production. the strategy highlights the importance of forestry and tourism potential of zemplén mountains, and lists the natural and cultural values (abaúj local development strategy, 2013). the analysis is focusing on potential and less on weaknesses. the concept is just mostly focusing on economic and demographic trends and agricultural production (table 1). the local development strategies do not focus on the real local resources, territorial differences nor potentials evolving from natural, cultural resources or local constrains. the only exception is tourism development where we can sometimes see the holistic spatial approach which intends to develop the region as a whole highlighting the development of the missing parts of the network and fosters local projects connecting tourism attractions, of course just in case there will be any initiatives. in rural development it is extremely important to harmonize the ecologic, social and economic aspects/needs of different land use forms evolving from the landscape conditions. this means diversity, which is manifested in the proper level of varied landscape functions, considering the rural economy providing diverse and wide range of economic activities (filepné et al., 2014; valánszki and filepné, 2015). economic diversity offers favorable conditions for the local population as well. this needs rural development policy responding the spatial development trends and differences following the landscape conditions stressing and using synergies and regional or systematic initiatives in spite of isolated projects. the disharmony of landscape functions weakens the population retention capacity of rural regions (filepné and valánszki, 2015). because of the extreme complexity of land use systems, the effective and long lasting changes can be realized only based on processes initiated and elaborated by varied stakeholders including all sectors of rural economy. the proposed land use changes have multiple economic, social conditions but their complex realization is needed for the improvement of the population retention capacity. unfortunately, in the present legal environment just fig. 7 general comparison of the level of landscape functions in the study areas landscape function analysis as a base of rural development strategies 25 isolated rural development projects can utilize and improve in complexity the local resources when just devoted local actors are capable to mobilize local engagement. while the rural strategies cannot reach the roots of local conflicts by deep landscape analysis the strategies will fail. table 1 general overview of the significance of landscape values in rural development strategies (cserhátalja local development strategy 2014-2020, abaúj local development strategy, 2013, rábaköz local development strategy 2014-2020); xxx – the main priorities of the development concept are related to the function; xx – the development concept stresses the enhancement or development of the mentioned function; x the landscape function is not stressed or neutral in the concept landscape function micro region csorna micro region gönc micro region pásztó nature protection value x xxx xx habitat value x xxx x landscape aesthetics xx x xx wine and fruit production xx xxx x arable potential x x x forestry x x x tourism and recreation xx xxx xxx accessibility x xx x economic value xx xx xx conclusions economic, social and environmental factors need to be considered in order to develop rural areas in a sustainable way. rural development strategies shall base on detailed landscape analysis assessing the landscape functions of the region. just based on grounded assessment will be possible to elaborate effective rural development strategies which respond the needs of the landscape, and local communities. exploring of the shortages of landscape functions in three study regions the rural development strategies were analyzed. our general conclusion is that the strategies lack detailed and complex landscape analysis exploring the limits and potentials. the strategies supported activities mostly related to marketing, business development, and tourism services. because of the financial shortages the range of supported activities were reduced recently which reduces the possibility of large scale complex programmes and gives way to small isolated developments. acknowledgements the research was supported by „únkp-17-4 new national excellence program of the ministry of human capacities”. references abaúj local development strategy 2013. abaúj leader local action group 2013. http://www.abaujleader.hu/strategiank/ ángyán, j. menyhért, z. 2004. adapting plant production, environmental and landscape management (alkalmazkodó növénytermesztés, környezetés tájgazdálkodás) szaktudás kiadó ház, budapest bastian, o. 1997. gedanken zur bewertung von landschaftsfunktionen – unter besonderer berücksichtigung der habitatfunktion, schnevedingen, germany: alfred toepfer akademie für naturschutz brandt, j., vejre, h. 2004. multifunctional landscapes – motives, concepts and perspectives. in: brandt, vejre, h. 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(ed.): ii. gazdálkodás és menedzsment tudományos konferencia: kecskemét, 2015. augusztus 27.: a vidék él és élni akar. 764–768. filepné kovács, k., valánszki, i, jombach, s, csemez, a, sallay, á. 2014. rural regions with different landscape functions: comparison analysis of two pilot regions in hungary. applied ecology and environmental research 12, 867–413. doi: 10.15666/aeer/1204_867886 hermann, a., kuttner, m., hainz-renetzeder, c., konkoly-gyuró, é., tirászi, á., brandenburg, c., allex, b., ziener, k., wrbka, t. 2014. assessment framework for landscape services in european cultural landscapes: an austrian hungarian case study. ecological indicators 37 (a), 229–240. doi: http://doi.org/10.1016/j.ecolind.2013.01.019 hungarian statistical office, www.ksh.hu konkoly-gyuró, é. 2011. conceptual evolvement of the landscape functions assessment. in: nagy g. g., kiss v. (eds.): borrowing services from nature – methodologies to evaluate ecosystem services focusin on hungarian case studies. ceeweb for biodiversity, budapest, 9–24. lamarque, p., quitier, f., lavorel, s. 2011. the diversity of the ecosystem services concept and its implications for their assessment and management. compes rendus biologies 334 (5-6), 441–449. doi: 10.1016/j.crvi.2010.11.007 mea (millennium ecosystem assessment) 2005. ecosystems and human well-being: biodiversity synthesis. world resource institue, washington d.c., 86 p. norgaard, r. b. 2010. ecosystem services: from eye-opening metaphor to complexity blinder ecol. econ. 69, 1219–1227. doi: http://doi.org/10.1016/j.ecolecon.2009.11.009 rábaköz local development strategy 2014-2020, rábaköz rural development association, march 2016 http://www.abaujleader.hu/strategiank/ http://doi.org/10.1016/s0921-8009%2802%2900089-7 26 filepné kovács et al. (2017) http://www.gymsmo.hu/data/files/teruletfejlesztes/2014_2020_ta jekoztato_anyagok/2016_04_15_hfs_rabakoz_videkfejlesztesi_leader_egyesulet_2014_2020.pdf new hungary rural development programme, darányi ignác terv 2014.https://www.mvh.allamkincstar.gov.hu/documents/123932/0/nhrdp_20140516.pdf sclößer, b., helming, k., wiggering, h. 2010 assessing land use change impacts – a comparison of the sensor land use function approach with other frameworks journal of land use science 5 (2),159–178.doi: 10.1080/1747423x.2010.485727 teir–területi információs rendszer/national database of spatial planning, hungary. https://www.teir.hu/ valánszki i., filepné kovács, k. 2015. land use function analysis for exploring spatial differences (tájfunkció elemzés a területi különbségek azonosításához) in: berkes j., kecskés p.: távol és közel, az elmúlt 25 év területi folyamatai, szerkezetei, intézményei, ahogy az új generáció látja: a ix. fiatal regionalisták konferenciájának előadásai. győr, magyarország, 281–292 willemen, l., hein, l, van mensvoort, m.e.f, verburg, p.h. 2010. space for people, plants, and livestock? quantifying interactions among multiple landscape functions in a dutch rural region. ecological indicators 10 (2010) 62–73. doi: 10.1016/j.ecolind.2009.02.015 introduction study areas micro-region of csorna micro-region of pásztó micro-region of gönc methods results and discussion ecologic and habitat values landscape aesthetics agriculture and forestry tourism and recreation accessibility economic value landscape functions in rural development strategies conclusions acknowledgements references recent dune migration along the coastal plain of canoa quebrada journal of environmental geography 12 (1–2), 23–32. doi: 10.2478/jengeo-2019-0003 issn 2060-467x recent dune migration along the coastal plain of canoa quebrada, ceará state, northeast brazil adriana albuquerque pedrosa1, vanda claudino-sales2*, iitabaraci nazareno cavalcante3, alexandre medeiros carvalho4 1secretary of education of the state of ceará, avenida general afonso albuquerque lima, 60822-325 fortaleza, ceará, brazil 2department of geography of the federal university of ceará (ufc), and master of geography of the state university of acaraú valley (uva), bloco 911, campus do pici, 60.440-544 fortaleza, ceará, brazil 3department of geology, federal university of ceará, bloco 912, campus do pici, 60.440-544 fortaleza, ceará, brazil 4marine sciences institute (labomar), federal university of ceará, avenida da abolição 3207, 60.165-081 fortaleza, ceará, brazil *corresponding author, e-mail: vcs@ufc.br research article, received 25 december 2018, accepted 14 march 2019 abstract in the coastal area of ceará state, northeast brazil, there are large mobile dunefields, including barchans, barchanoid dunes and sandsheets. the migration rate of these dunes, as measured by several studies, varies between 32 m/y and 9 m/y. this paper analyzes the migration of the dunes in canoa quebrada beach, located in the eastern coast of ceará state, using remote sensing of aerial photos and satellite imagery from 1988 to 2013 (25 years). the resulting data indicate an average migration rate varying from 1.8 m/y to 9.3 m/y. this is the lowest rate of migration measured for large and undeveloped mobile dunes in ceará state. the analysis indicates that the element responsible for this low rate is the low wind speed. however, the installation of wind power turbines in the area – which demanded the fixation of part of the dunes to prevent the equipment from being buried and from aeolian erosion – might be another reason for the decreasing dune migration. the dune migration decrease may increase the sedimentary deficit in the coastline downdrift of canoa quebrada beach. keywords: dune migration, coastal dynamics, northeastern brazil, coastal development introduction mobile aeolian dunes are accumulations of medium to fine sands characterized by the absence of vegetation cover or cementation. they occur in coastal plains, continental desert areas, and in the vicinity of fluvial and lacustrine beaches and plains. the mobile aeolian dunes migrate when they are mobilized by winds and, therefore, are constantly changing form and position while the wind reorganizes their sand disposition. in general, it is considered that the intensity of dune migration depends on the variations of the intensity and direction of annual, seasonal and daily winds, as well as of the turbulence patterns of winds (e.g. tsoar et al., 1999), of the granulometry of the sediments (e.g. kocurek and lancaster, 1999; livingstone et al., 2007; potter and weigand, 2016), of the topography of the surface (e.g. bristow et al,, 2000; necsoiu et al., 2009), of the intensity of atmospheric precipitation (e.g. hunter et al, 1983; maia et al., 2005; forman et al,. 2009), of the moisture content of the sands (e.g. sherman and bauer, 1993; tsoar and arens, 2003; potter and weigand, 2016) and of the wind direction related to the shoreline orientation (carvalho et al., 2016). it is considered that wind velocities of the order of 3 m/s are able to mobilize medium sands (paula et al., 2016), and that if conditions are suitable – e.g. dry, open sand surface the wind can transport even the coarse fraction of the sand (györgyövics et al., 2014). small dunes migrate faster than larger ones (e.g. jiminez et al., 1999; carvalho et al., 2006), and displacements of 1 m/year can take place during the action of strong winds (e.g. cooke et al., 1993). in the sahara desert, measurements indicate a migration rate of the order of 50 m/y for barchan dunes (vermeesch and leprince, 2012). in antarctica, a study identified a rate of dune migration of 0.5 to 1.3 m/y (bristow et al., 2010). a study about rates of dune migration of active subarctic dunefields indicates an annual migration varying from 0.5 m to 1.5 m (necsoiu et al., 2009). in great britain, a research about the rate of migration of transgressive dunes gave an annual average of 1 m (bailley and bristow, 2004). in the great lakes area of united states, a study of the migration of continental dunes in a lake shoreline attained a maximum rate of 3.3 m/y (kilibarda and shillinglaw, 2014). at the taklamakan desert, china, measurements resulted in rates of dune migration of the order of 7.2 to 5.5 m/y (zhibao et al., 2000). dune migration in an estuary in new zealand was identified at a rate of 5 m/y (shepperd, 1987). in the coastal area of ceará state, in the northeast of brazil (fig. 1), large mobile dunefields formed by barchans, barchanoid dunes and sandsheets occur along its 573 km of length. the velocity of dune migration is high and has already been measured in some segments of its west coast. the resulting values appointed to a migration of the order of 17 m/y in jericoacoara (jiminez et al., 1999), of the maximum order of 12.5 m/y in 24 pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. paracuru (castro, 2005), of 32 m/y for small barchans and of the order of 23 m/y for large barchanoid in the same area (carvalho et al., 2006), and from 14 m/y to 19 m/y in flecheira/baleia beaches (carvalho, 2003). up to now, no measurements were made for the east coast of the state, a segment that is characterized by the presence of seacliffs extending for around 100 km and by less intensity of wind speed (maia, 1998). it is important to mention that along this coast, wind-turbines have been installed in the last decade, which might affect the migration of the dunes. nevertheless, no measurements have been made to evaluate the extent of the change. in the other states that compose the brazilian equatorial northeast, the intensity of dune migration defined by several studies present the same patterns of those identified in the coastal area of ceará state: the rate of migration is in general higher than 10 meters per year. illustrating this pattern, it is possible to highlight the migration in the coastal area of piauí state of the order of 21 m/y; in the state of maranhão, where it can reach a maximum value of 25 m/y (santos and santos, 2015); and, finally, in the state of rio grande do norte, where the dunes migrate with an intensity of at least 23 m/y (carneiro et al., 2012). the migration of dunes along the ceará state coastal area is very important for the sedimentological budget of the area, considering that the region is semi-arid, with small production of fluvial sand. for this reason, an insignificant amount of sand is transported by rivers to the ocean, in order to nourish the beaches downdrift (maia, 1998). the dunes, in doing the bypass across headlands and fluvialmarine plains, feed rivers with sediments, in such a way to contribute to the equilibrium of the coastal area (maia, 1998; claudino-sales, 2002; carvalho, 2003; meireles, 2011; claudino-sales et al., 2018). in terms of environmental problems and dune mobilization, it is worth mentioning that in some places, there are conflicts between mobile dunes and urban structures, which have been installed in their path of migration. in this paper, the migration of the dunes in the coastal area of canoa quebrada beach, located in the east coast of ceará state, is analyzed. the rate of dune migration at this area, identified here for the first time, has a current behavior completely different from the rate of migration identified for the other segments of the brazilian northeast coast. the characteristics, as well as the reasons for the particularity of dune migration processes in canoa quebrada – such as natural driving forces, as well as those controlled by social activities, e.g. wind-turbine plants and tourism – are analyzed and discussed. study area the coast of ceará state, northeastern brazil (fig. 1), consists mostly of long and wide quartz sand beaches, interrupted by small estuaries with mangrove formed by intermittent rivers, as well as by seacliffs, beach-rocks and headlands. the area is characterized by the presence of large transgressive coastal dune complexes distributed up to 6 km landward of the coastline. small barrier-islands are present, especially in the west coast (claudino sales, 2002; hesp et al., 2009). tertiary rocks, represented by the “barreiras formation,” is the most important type of deposition in terms of spatial distribution and control of regional coastal sedimentology. the barreiras formation displays a fig 1 location of the study area, the canoa quebrada coastal plain, situated at the east segment of ceará state coast pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. 25 complex lithology ranging from conglomerates, sandstones and mudstones of terrestrial (bigarella, 1975) and marine (claudino-sales, 2002) origins. it creates a low-lying tabular surface with less than 40 m in elevation that extends from the shoreline to 60 km inland. in the vicinity of the shoreline, the tabular surface is covered by aeolian sediments from both active and inactive dunes. in the east segment of the coast, barreiras formation outcrops as seacliffs 7 to 15 m high. in addition, it makes several headlands along the coast. (e.g. claudino sales and carvalho, 2014). despite its tropical subequatorial location, ceará state is dominated by an unusual semi-arid climate. the semiarid characteristics are not directly reflected in the total annual rainfall value, which is relatively high compared to other semi-arid areas in the world (inpe, 2018). the semiaridity is reflected in its great inter-annual variability, with more than 90% of the rain falling during the 3-month wet season, between mid-march and mid-june. temperature remains largely constant throughout the year, with monthly averages ranging between 25.5 °c and 27.5 °c in the coastal area (inpe, 2018). due to this persistent high temperature and the resulting high potential evaporation, a severe water deficit of more than 1,000 mm occurs in the dry season in the coastal region (semace, 1997). in addition, rivers with even drier catchment area are mostly periodic waterflows, not adding any important amount of sand to the seashore (maia, 1998). the climatic conditions of northeastern brazil are mostly controlled by the atlantic ocean circulation system known as the “intertropical convergence zone”itcz (e.g. wang et al., 2004). itcz is related to the sector of the globe where humid atmospheric masses coming from northern and southern hemispheres collide. during the first semester of the year (especially during march and april), the itcz is at its southernmost position over ceará, resulting in the peak rainy season. after april, precipitation starts to decrease as the itcz shifts northward, reaching its northernmost position during the second semester of the year (september and october), leading to the peak of the dry season. another global scale control on the region’s climate is the el niño southern oscillation (enso) cycle. maia et al. (2005) pointed out that enso tends to strengthen the dry season in the equatorial segment of the northeastern brazil, while hastenrath and heller (2006) suggested that it strengthens the wet season. in such a context, it is evident that, as compared to the itcz, the influence of enso on the regional climate regime is not yet well understood. in the ceará state coastal area, the wind conditions vary considerably from dry season to wet season, controlled by the seasonal migration of the itcz. it demonstrates a similar pattern as that of the precipitation variation, but with an opposite trend. generally, as the precipitation rate decreases, the wind speed increases and reaches a peak speed during the peak dry season. wind speed may exceed values of 15 m/s, but it goes from 4 m/s in the wet season to 8 m/s on average in the dry season, with annual averages of 5.5 m/s (e.g. maia, 1998). the wind has a constant easterly direction, controlled by the trade winds. a unique aspect of this stretch of coastal area is that it is never influenced by severe storms. driven by the persistent and strong unidirectional winds especially during the dry season, as well as to the dominantly dissipative or intermediate type of meso-tidal beaches (maia, 1998, claudino-sales, 2002; carvalho and claudino-sales, 2016; pinheiro et al., 2016), dunefields are very well developed along the ceará coastal area. the dunes occur as both stable vegetated older dunefields and modern transgressive dunefields (e.g. claudino-sales, 2002; claudino-sales and peulvast, 2002). luminescence dating of sand samples (~1 m below the surface) from vegetated dunes along the coasts of ceará yielded ages ranging from 135 ky to 100 yr bp (tsoar et al., 2009). generally, the dunefields are composed of lunar-shaped/barchans and transverse dune ridges, with fixed parabolic “hairpin” dunes and aeolianites in the seaward segment of the coast (maia, 1998; claudino-sales, 2002; claudino-sales and peulvast, 2002; carvalho, 2003; carvalho et al., 2010). mobile transverse dunes vary in height from less than 15 m to 55 m. the vegetation in the dunefields is characterized by the presence of species of the halophile-psamophile community (especially ipomoea pes-caprae and sporobolus virginicus) in the mobile segment, and by species of the coastal tropical forest (especially anacardium occidentale and byrsonima sericea) in the vegetated dunefields (moro et al., 2015). the wave conditions in the ceará state coast are also strongly influenced by the persistent and unidirectional trade winds. according to the national institute of navigation research – inph (1996), the predominant wave direction as measured at pecém beach is 90°, i.e., approaching from the east. the waves are mainly of the sea type, with occasional occurrence of ne swell originated in the northern hemisphere from november to march (maia, 1998). the most frequently occurring wave heights range from 1.0 to 1.5 m, with period of 5 s (claudino-sales et al., 2018; maia, 1998). the ceará state coastal area is characteristic of a semidiurnal mesotidal regime with a spring tidal range of approximately 3.1 m (dnh, 2018), and an average range of 2.64 m. canoa quebrada beach, as studied in this paper, is located in the east segment of ceará state coast (fig. 1). the studied coastal segment is 11 km long, occupying an area of 2,500 ha. the landscape, as see in the geomorphological map (fig. 2), is characterized by the presence of long sandy beaches interrupted at the west by the mouth of the jaguaribe river – where the fluvial-marine plain is colonized by mangrove. the strand is marked by the presence of active seacliffs shaped in the barreiras formation (fig. 3a), which extend for around 30 km from se to nw, as well as by littoral bars (see figure 2). coastal tablelands are also modelled in the barreiras formation in the inner coastal area, and are largely covered by mobile dunefields and interdune ponds (figs 2 and 3b) (pedrosa, 2016). the mobile dunefields of canoa quebrada are of the barchans type (lower number), barchanoids (abundant) and sandsheets (dominant) (pedrosa, 2016). there are also semi-fixed dunes in contact with the mangroves (figs. 2 and 3c). the vegetation of the mangrove is, in this case, the major factor in the fixation of the transgressive dunes that 26 pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. migrate into the fluvial-marine plain direction. the dunes present maximum heights of 34 m (fig. 3d) (pedrosa, 2016). they are formed by medium and fine well-selected sands (maia et al., 2006). the pluvial regime in canoa quebrada is mild tropical. the annual average precipitation rate reaches 1,024 mm (funceme, 2015). september is the driest month, with only 5 mm of rain. the majority of the precipitation occurs in march, with a monthly average of 264 mm. the annual average temperature is 27.1°c (funceme, 2015) (fig.4). most of the studied area is part of the “area of permanent preservation – apa” of canoa quebrada (for location of the apa, see figure 2). the apa was defined by state law in 1998, and has the goal to preserve the biotic communities, fixed and mobile dunes, seacliffs, ponds, fig 2 geomorphology of canoa quebrada beach, with indication of the presence of an area of permanent preservation (apa) in the study area fig. 3 coastal features in canoa quebrada beach. a. seacliffs modeled on tertiary sediments in canoa quebrada beach b. mobile transgressive dunefields with interdune ponds. c. transgressive dunes being fixed in contact with mangroves at the fluvial plain of jaguaribe river. d. thirty-four meters high barchan dune in canoa quebrada beach coastal area pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. 27 mangrove, reefs and soil. it also allows the development of the land, in the measure that the uses and occupations intended do not result in degradation of the natural attributes of the environment. the principal economic activity practiced in the apa is geotourism and ecotourism. in the last decade, wind-turbine plants were installed. fig. 4 graphic of temperature (t) and precipitation (p) in canoa quebrada coastal area (meteorological station placed at aracati, 30 km from the study area) for the year 2015 methods the dune migration rate analysis along the canoa quebrada municipality covered the interval of 25 years, related to the period 1988 2013. therefore, aerial photographs, scale 1: 25,000, of the year 1988, as well as satellite images “quick bird” of the years 2004, 2010 and 2013 were used. besides google images, those were the only images found for the area in the brazilian public and private sources. the location of the transects used in this research using the photographs and satellite images is indicated in figure 5. the determination of the migration rate of the dunes was obtained with the help of the tool “digital shoreline analysis system – dsas 3.2”, applied to the arcmapgis 9 software. the dsas is an extension that enhances the normal arcgis software functionality. it allows the user to calculate change rates of a statistical series, considering the time and the multiple positions of successive lines drawn in the satellite images of the coastline (oliveira, 2005; thieler et al., 2005). the tool was used for this study, to allow measuring the lines of advancement of the dunes along the coastal plain. the dsas works by generating orthogonal transects at a spacing defined by the user, which in this case was 200 m. it calculates the change of rates between space and time, generating the statistics that are shown in an attribute table. the statistical method tool was the linear regression (lrr). the dsas tool was applied from the creation of lines in shapefile format in arcmapgis 9 software. the boundary line of the dunefields, on the leeward side, was created for each year of observation, enabling the multitemporal analysis. a baseline was acquired, also in shapelife format, set perpendicular to the direction of dune migration. the observation of the direction of migration was made using the satellite images, overlapping one and the other. finally, the tool that creates the transects was applied, also in shapefile format, for calculation of the migration rates. each transect passing the lines calculates the rates, considering the space and the existing time between them. fig. 5 location of the transects made in the dunefields of canoa quebrada, in order to calculate the rates of migration of the dunes 28 pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. the value that each transect calculates matches the given point of the dune. therefore, the migration rate of a dunefield can be acquired by calculating the average of all transects. the precipitation, temperature and wind speed data were collected in the brazilian and ceará state weather centers, at the meteorological station of aracati city, 30 km from the study area. for the precipitation and temperature, monthly raw numbers were obtained at the ceará state meteorological and for water resources foundation (funceme), and statistics were made to give the annual averages for the time series analyzed. for the wind, raw monthly data was collected in the forecast weather and climatic studies center of the national institute of spatial research (cptec/inpe), and statistics were produced to attain the annual average numbers for the time series analyzed. there was no available wind data for the years 1988 and 2004. for the physical recognition of the study area, as well as to evaluate the impact of tourism and turbinewind plants in the natural dynamic, fieldworks were made in the dunefields, using a dune buggy. in addition, one day of navigation was done in a fishing boat in the channel of the rio jaguaribe, to identify the eventual impact of the migration of transgressive dunes toward the mangrove forest. the field trips took place in the years 2016 and 2017. results and discussion the dune migration rate of the canoa quebrada dunefield obtained within 25 years is shown in figure 6 this value was approximately 7.25 m/y. the greatest migration rate obtained was 18.4 m/y (transect 39, see figure 6), while the lowest was 0.5 m/y (transect 2, see figure 6). this migration rate appears to be much lower than those set for other sectors of the coastal zone of ceará state and other states of northeastern brazil, as indicated by maia (1993), jimenez et al. (1999), carvalho (2003), castro (2005) and carvalho et al (2006), carneiro et al. (2012) and santos and santos (2015). in the 1988-2004 period, the largest averages of migration rates showed values of the order of 9.3 m/y. in the spaces of time between 2005-2010 and 2011-2013, there was a decrease of the average rates of dune migration. in the period of 2005-2010, the average rate was approximately 3.5 m/y, and in the last interval, only 1.8 m/y. the relationship between migration rates and the annual precipitation in the dunefields in the analyzed intervals is shown in figure 7. the highest rainfall occurred in the period of 2005-2010, exceeding 1,000 mm/y. much less rainfall occurred in the 2011-2013 period, reaching 600 mm/y. comparing the intervals 1988-2004 and 2005-2010, there was a decrease in the average migration rate of the dunes while there was an increase of atmospheric precipitation. this confirms the normal behavior of dune mobilization, presenting a lower rate with the increasing rainfall. however, it appears that in the interval 2011-2013, even with decreased annual rainfall, there was not an increased migration rate of the dunes. instead, the migration of the dunes for this time interval was also lower. fig. 6 rates of dune migration in canoa quebrada for the studied time series fig. 7 rates of migration and intensity of precipitation in canoa quebrada for the studied time series thus, the data in relation to the canoa quebrada beach for the last time interval seem to contradict the relationship between the decrease of annual rainfall and increase in the average rate of dune migration, as seen in figure 7. what is evident in the data of canoa quebrada is the occurrence of decreasing migration rates for the most recent time series. the annual average wind speed obtained for canoa quebrada is below the speed measured in other parts of the ceará state coast in previous decades: it was of the order of 1.45 m/s in 2010 and of 1.65 m/s in 2013 (cptec/inpe, 2015). the short interval of time of these data is not enough to affirm whether it is a systematic or just an eventual situation. pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. 29 the mobile dunes of canoa quebrada migrated in the direction of the fluvial plain of the jaguaribe river. figure 8 shows the current average distance of the lee face of the dunes up to the riverbed. this distance is 1,432 m on average. the farthest point (04) measures 2,479 m, while the nearest (03) lies at 603 m. during parts of the holocene, the mobile dunes of canoa quebrada fed the jaguaribe river with sediment. the river, in turn, probably deposited the sands in the ocean through its near mouth. thus, the coastal sedimentary budget should have some sort of balance: the sediments would be transported by the action of winds from the beaches to the coastal zone’s interior. part of this stock would go back to the ocean through the bypass of dunes in headlands and by the supply of rivers. the sediments returned to the ocean by rivers would feed new beaches downstream, creating a retro-feeding mechanism capable of ensuring the balance of the shoreline and the control of coastal erosion. with decreasing migration intensity of the dunes toward the river in the canoa quebrada coastal area, the amount of aeolian sand that fed the river flow became smaller. according to the average distance of the sliding face of the dunes to the river, and if the current aeolian regime continues, the dunes would take about 198 years to reach the riverbed, or 84 years, considering the nearest point. thus, the sediment yield to the ocean by the jaguaribe river is certainly decreasing, which may be contributing to the growth of the coastal erosion that occurs in the beaches downstream of the river mouth. this erosion has been detected by morais and pinheiro (2011), who also considered the role of damming of the river in the last decades, as well as other occupation of the fluvial marine plain by social activity, such as shrimp farms. the considerable decrease in the migration rate o f the dunes in canoa quebrada in the last decade, as measured, can also result in part from the forms of land use and occupation. indeed, since mid-2009 wind turbines are being installed by private investors in the dunefields of the study area, as allowed by government, aimed to produce wind energy for regional consumption (fig. 9). for the installation and maintenance of the wind power plants, the installation of a network road for access was necessary, as well as the adoption of measures to protect the base of the structures from burial by sand and wind erosion. therefore, a process of artificial fixation of sand began, using straw (figs 10 and 11). the migration speed of the dunes was certainly altered to lower values with the implementation of containment techniques for mobile sands. indeed, from 2010, the dunes presented little annual migratory movement, as identified by the analysis of satellite images. nevertheless, the wind fig. 8 distances from the lee face of the mobile dunes to the jaguaribe river estuary situated at the west segment of canoa quebrada coastal area 30 pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. fig. 10 location of the introduction of straw to promote the fixation of the mobile dunefield of canoa quebrada, in order to protect the aeroturbines from burial by the sands and from aeolian erosion speed was a little higher for the years 2011 -2013, as shown in figure 6. the fixation of the mobile dunefields of canoa quebrada for the purpose of protection of the plants for aeolian energy is not the only threat to the dunefields and to the apa there. the opening of circulation routes to facilitate the traffic of buggy type vehicles, which carry tourists on the dunes, has to be mentioned (figure 12). the village of canoa quebrada is one of the most important tourist destinations of the state, and is national and world renowned. the tourism flux is intense, and the traffic of buggies is considerable. this can also be a factor in the compaction of sand and of the reduction of the dune migration rates. dwindling sediments already present in the riverbed due to the construction of dams (around 30,000 tons of sediment annually retained: morais and pinheiro, 2011), particularly the large dam “castanhão” at the end of the 1990s, the additional decrease of intake sediment caused by decreased dune migration in canoa quebrada on the riverbed possibly will result in non contribution of sediments from the jaguaribe river to the ocean. it is considered here that without sediments, and taking into account the littoral dynamics of the study area, the river runs the risk of having its mouth barred by the construction of sand barriers formed by sand coming from the ocean, deposited by the action of waves and longshore drift. fig. 9 map of use and occupation of the study area, showing the location of wind-turbine plants pedrosa et al. 2019 / journal of environmental geography 12 (1–2), 23–32. 31 fig. 11 dunes fixed by straw in the coastal plain of canoa quebrada. (source: google earth) fig. 12 unpaved road (arrow) built on the mobile dunefields to allow the use of dune buggy vehicles, in order to answer tourist demands conclusions the research synthesized here indicates the occurrence of a low annual average migration rate of the mobile dunes along the coastal plain of canoa quebrada beach within 25 years, between 1988 and 2013. in addition, it appears that this reduction was increasing at the end of 2013. the migration rates (with minimal of 1.45 m/y) are considered lower when compared to the other sectors of the northern brazilian area, as indicated by maia (1998), jiminez et al. (1999), carvalho (2003), castro (2005), carvalho et al. (2006), meireles (2011), carneiro et al. (2012) and santos and santos (2015). the data also showed a low annual wind speed, despite the decrease in precipitation in the last five years, which is the normal trend in the brazilian northeast. the decrease in precipitation illustrates the great drought embracing the northeast region in recent years, through the action of el niño. such a situation seems to disprove the idea that the el niño action increases the migration of dunes in the coastal zone of ceará state, as indicated by maia et al. (2005). on the other hand, the low average migration rate of the dunes along the coastal plain of canoa quebrada, as identified in the data presented here, is clearly due to the low intensity of the wind in the area. indeed, even with the decrease in precipitation, the migration rate did not increase between the observed time intervals. this seems to indicate that the main element responsible for dunes migration is wind speed. the installation of straw in some segments of the dunefield also contributed to a lesser rate of dune migration. the moisture content present in the sands resulting from precipitation and other elements of the natural environment such as the topography of the land and the geometry of the dunes seem to be secondary factors. despite the existence of an area of environmental preservation apa in the dunefields of canoa quebrada, it is clear that some activities permitted by public agencies are degrading the dune ecosystem. this is the case of the measures taken to ensure the maintenance of the turbines for wind energy installed in the dunefields, and the resulting compaction from traffic by tourist passenger cars. these activities, approved or known by the state and local public agencies responsible for monitoring and ensuring the local environmental preservation, clearly work against the integrity of the dunefields. they are also possibly responsible for the lower rate of dune migration in the last analyzed interval of time. together, the natural dynamics and the dynamics induced by social activities in the coastal area of canoa quebrada have pointed to a virtual stabilization of the local dunefields, because of the increasing decline of the migration rates of the dunes. this may have regional implications, such as the lower contribution of aeolian sand to the sedimentary budget along the east coast of ceara state. this stabilization can result in alterations in hydraulic and sedimentary dynamics of water resources coupled to the dune system, which can produce a magnification of the coastal erosion underway downdrift of canoa quebrada beach. these findings should be incorporated into integrated coastal zone management strategies for the area, especially those associated with coastal erosion and preservation of the environment acknowledgments we thank roger morton for his editorial assistance. references bailley, s.d., bristow, c.s. 2004. migration of parabolic dunes at aberffraw, anglesey, north wales. geomorphology 59(1-4), 165–174. doi: 10.1016/j.geomorph.2003.09.013 bigarella, j.j. 1975. the barreiras group in northeastern brazil. annals of the brazilian academy of science 47(supp), 366–392. bristow, c.s., augustinus, p.c., wallis, i.c., jol, h.m., rhodes, e.j.2010. investigation of the age and migration of reversing dunes in antarctica using gpr and osl, with implications for gpr on mars. earth and planetary science letters 289 (1-2), 30–42. doi: 10.1016/j.epsl.2009.10.026 bristow, c.s., bailley, s.d., lancaster, n. 2000. the sedimentary structure of linear sand dunes. nature 406, 56–59. doi: 10.1038/35017536 carneiro, m.c.s.m., lima, m.o.s., sá, l.a.c.m., araújo, t.c. 2012. monitoramento da tendência de deslocamento do campo de dunas de rio do fogo – rn utilizando lidar aeerotransportável. iv simpósio brasileiro de ciências geodésicas e tecnologias de informação (monitoring of the displacement tendency of the rio do fogo rn dunes field using aeerotransportable lidar. iv brazilian symposium on geodesy science and technology of information), recife, sbg. carvalho, a.m. 2003. morfodinâmica costeira entre cumbuco e matões – costa noroeste do estado do ceará. enfâse nos processos eólicos. 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(2015), temperature changes, documentary evidence about seasonal extremes and archival evidence. the comparison shows that palaeoclimatology proxies are important sources of information regarding changes in rice cultivation. it also indicates that the ottoman archive is a valuable source of possible phenological data. thus, research sources from nature and societies complement one another. the comparison also demonstrates that climate change during the ottoman empire’s reign showed regional differences, and a local comparison of phenological data and palaeoclimatological data can explain more about the effects of the little ice age (lia) on the empire. keywords: climate history, environmental history, ottoman history, rice farming, phenology, palaeoclimatology introduction the climate extremes of the little ice age were a trigger for the development of the modern state’s institutional structure (parker, 2013). after the so-called earlymodern gunpowder revolution of the 16th century, anthropogenic intrusions into the environment grew significantly all over the world (ágoston, 2009). new institutional bodies in absolutist states enforced the large-scale displacement of plants, animals, human beings and raw materials. empires employed plant breeders, who experimented with new hybrid forms to increase crop yields and enhance variation. the early modern era was a period of agronomic challenges (murphy, 2007). the appropriate location of plantations, using the right varieties, coordinating the workforce and ensuring sustainable production was a great institutional challenge at a time of climate change. cash crops such as sugar cane, rice, coffee, cacao, tea and tobacco had a substantial social and environmental impact in the regions where they were planted. rice was one of the products that transformed the socio-ecological landscapes in its foodway from china and india to the middle east, europe and the americas. sugar cane and rice were among those plants diffused westwards from south asia to the middle east and europe during the arab agricultural revolution between the 8th and 13th centuries (watson, 1981; canard, 1959). rice, the main staple of indian and chinese cuisines, first entered the courts of middle eastern sultans on its way from persia and the mamluk empire to ottoman lands. the demand for rice as a luxury cash crop in growing local markets rose hand in hand with the increasing specialization of production activities in ottoman cities. although rice production was known in southeast europe before the 14th century, there was no extensive production before the ottomans founded institutionalized rice plantations in the 14th and 15th centuries (i̇nalcık, 1982). the ottoman empire was one of the empires that introduced agronomic challenges and experienced fundamental institutional changes in the early modern era. rice plantations in the ottoman empire have drawn the attention of many scholars for their political and economic importance (gökbilgin, 1952; barkan, 1963; beldiceanu et al., 1978; i̇nalcık, 1982; arıkan, 1990; venzke, 1992; andreev et al., 2003; karagöz, 2004, evered et al., 2015; amedosky, 2017; kul, 2017). promitzer (2010), evered et al. (2015) and gratien (2017) introduced an environmental perspective to the study of 19th and early 20th century rice plantations. shopov (2020) draws attention to early modern intrusions on the landscape, deforestation and the societal effects of rice plantations in plovdiv, bulgaria. however, in the above studies, climate change has mailto:oezlemsert@gmail.com 2 sert 2021 / journal of environmental geography 14 (1–2), 1–14. received little attention. amedosky (2017) relates the fluctuations in rice harvests to the environmental conditions of the little ice age in the balkans. she refers to tabak (2008), connecting the humid conditions of the little ice age with the introduction of aquatic crops. andreev et al. (2003) mention drought and revenue problems in the 17th and 18th centuries. in these studies, neither proxy data from archives of nature (i.e., tree rings) nor speleothem or pollen analysis have been used. the present article aims to compare palaeoclimatology data with documentary evidence about institutionalized rice plantations of the ottoman state, thus it is a first attempt to find rice-related phenological data in ottoman sources as potential material for the identification of climate history. the study addresses the effect of climate variability on rice plantations. available phenological data is compared with regional tree ring data. the june-july-august drought index (pdsi) reconstruction maps by cook et al. (2015), research on temperature changes and historical data on climate extremes are compared with available yields, prices and other historical evidence about rice plantations. study area ottoman rice plantations were situated in the river valleys of the region between the tigris and the danube, between 30°–46° latitude and 19°–43° longitude, where temperatures were over 20 °c in the growing season and water scarcity was rare. figure 1 shows the distribution of ottoman rice plantations in relation to: a) may-june-july mean temperatures; and b) annual mean precipitation values. the location of plantations has been ascertained from studying documentary evidence in decrees, cadastres, rice tax office books and the rice paddy tax registers. the survey mainly focuses on areas where both documentary evidence and palaeoclimatology data are sufficient; therefore, it includes t he region of anatolia and the balkans but does not cover iraq and egypt. this large study area has a variety of very different climatic conditions. the strong influence of the east atlantic/western russia’s seesaw teleconnection pattern is sometimes eviden t between anatolia and the balkans (roberts et al., 2012). at times, while central anatolia is dry, western europe has higher precipitation rates. constantinidou et al. (2019) define six climatic regions (anatolia, balkans, western, central and eastern mediterranean, and mesopotamia) depending on the radiative index of dryness, the fuel dryness index and the water limited yield of winter wheat. however, even in this differentiated regional model, both anatolia and the balkans have sub-climatic regions as shown below (fig. 2). anatolia while central anatolia is often hit by extreme drought, the black sea region and the aegean coasts of western anatolia are not influenced as much. the parallel mountain chains in the east -west direction of the mediterranean and the black sea region build a barrier, thus rain clouds transform humid air into rainfall on the slopes (akkemik et al., 2005). whereas the mean annual rainfall in continental central anatolia is only about 300 mm, the western and eastern black sea measures 1,000 mm and the western mediterranean coasts 800 mm (türkeş, 1996; akkemik et al., 2005). based on annual precipitation totals from 96 stations in turkey, türkeş et al. (2011) have defined seven rainfall regime regions in the country: the black sea, marmara transition, the mediterranean, mediterranean transition, continental mediterranean, continental central anatolia and continental eastern anatolia. moreover, by using spectral clustering of precipitation values, türkeş et al. (2011) have defined 800 mm in eight resultant subregions: the black sea, northwest turkey, the southern aegean and western mediterranean, the mediterranean, west continental central anatolia, east continental central anatolia, continental eastern and southeastern anatolia. since the rainfall regime is very important across the breadth of this study, the simplified climate region definition derived by türkeş et al. (2011) is considered an appropriate categorization tool. fig. 1 actual may-june-july mean temperatures [°c] (left) and annual mean precipitation [mm] (right) of the study area according to hersbach et al. (2020) and the location of studied ottoman plantations sert 2021 / journal of environmental geography 14 (1–2), 1–14. 3 the balkans the köppen-geiger climate classification for the balkans (peel et al., 2007) is not sufficient to show the study area’s regional climatic differences. the balkans also have sub-climatic regions: popov (2018), for example, modified the köppen-geiger classification for the vardar, struma and mesta valleys. similarly, using contemporary data and projections, beck et al. (2018) drew a new köppen-geiger climate classification using a 1 km resolution map for 1980–2016. this map shows regional differences better than the köppen map. beck et al. (2018) also made another projection map for 2071– 2100. the two maps show a great change in climate zones, which is a suitable warning against using current data for historical studies. in this study, the entire region is called southeastern europe. the comparison of documentary evidence and palaeoclimatology data focuses on seven regions: continental central anatolia, the black sea region, the mediterranean, southeastern anatolia, southeastern europe and marmara transition. the locations that have comparable data is restricted. fig. 2 shows the major rivers and the locations discussed in the results section via a colour code. since data that provide indications about annual yield and price variability are restricted, not all locations are discussed in the study. data and terminology the ottoman government gave particular importance to the production of rice as a cash crop. the administration of rice plantations required great organizational capacity for building canals and repairing them in case they were damaged by floods. new plantation areas were often allocated to waqfs, islamic charitable foundations. in southeastern anatolia, the previous mamluk system of rice growing was assimilated. the resultant ottoman system was a challenging system that depended on waqfs to open new land for plantations. waqfization also provided the cash flow that the gunpowder empire needed for its armies. high-ranking statesmen and affluent people donated income from revenue generating sources to uphold the pub lic good and simultaneously entrust their estates to family members. after mehmed ii’s reign (1444 –1446 and 1451–1481), the state employed a group of cultivation experts (çeltikçi) to implement and rehabilitate rice farming, organize the workforce and ensu re sustainable production (i̇nalcık, 1982; emecan, 1993). waqfization went hand in hand with the spread of rice plantations in the balkans (shopov, 2020). the branches of the rivers were allocated to a tax farmers. fig. 2 major rivers and locations discussed in the results section. colour coding of the locations: continental central anatolia (red), the black sea region (blue), the mediterranean (burgundy), southeastern anatolia (orange), southeastern europe (navy blue) and marmara transition (green) 4 sert 2021 / journal of environmental geography 14 (1–2), 1–14. each river and creek, which was used for r ice production, were listed in registers. the terminology in these registers gives an indication about the organizational principles that were used. to guarantee that correct varieties were used, the administration often supplied seeds to start plantations. controlling the rice variety not only secured higher revenues but also prevented losses caused by planting mixed varieties. controlling the varities was so important, that tohum, which literally means “seed”, became a measurement unit for production lots. rice plantations were so highly regarded by the state that there is an immense volume of data. the use of archival data as historical evidence requires available documents to be classified and their potential analyzed. decrees important events, changes in production or changes in the organization of production were recorded in decrees called mühimme. the data in these decrees provide evidence of weather extremes such as floods and droughts that resulted in reduced yield. the decrees also include information about geographical distribution. however, they are not useful for tracing gradual changes in rice production. cadastres cadastres (tapu tahrir and i̇cmal registers) are valuable because they give data about local production and the distribution of lots to tax farmers (mukataa) for 2–3 years. however, the data is not adequate enough to compare annual yields with climate variability. rice tax office books the anatolian fiscal office kept separate registers for cash crops such as silk, tobacco, coffee and rice. the first rice tax office book (çeltik rüsumu kalemi or vâridât-i şikk-i sânî kalemi) was started in 1524 and ended in 1532 defining the annual allocation of river branches to tax farmers (boa d.çrs.d.25994). this book is valuable because it shows that the branches of the rivers were registered as early as the first half of the 16th century (fig. 3). although these entries do not give data about the climate, similar register books could be beneficial for future land surveys. the documentation of each branch of the river from the 15th to 20th centuries is vast and the registers become more elaborate from the 16 th century onwards. the second rice tax office book dated up until 1551, which originated from skopje (üsküp), lists the allocation of lots (boa d.çrs.d.25995). the third book is from plovdiv (filibe) and pazardzhik (tatarpazarı) (from now on modern names will be used). there are various entries from 1659, 1664– 1665 and 1673. (boa d.çrs.d.25996) the fourth register is also from plovdiv and pazardzhik for 1674 (boa d.çrs.d.25997). the fifth is also from the same region and is dated 1684–1688 (d.çrs.d.25998). the sixth is from p azardzhik and is dated up to 1780 (karagöz, 2004; d.çrs.d.25999). the last book is from düzce dated 1829 (boa d.çrs.d.26000). the seventh rice tax office books show the allocation of river branches in skopje on the vardar river, plovdiv and pazardzhik on t he maritsa river, and düzce on the sakarya river in anatolia (fig. 2). rice paddy tax register documents rice paddy tax register documents (çeltik rüsümu evrakı, fig. 4) are records about the allocation of paddy fields, the changes to tax farmers’ lots (mukataa) and their administration. there are four books, the first dating from 1688 to 1728 (boa d.çrs.1), the second from 1734 to 1761 (boa d.çrs.2), the third from 1762 to 1776 (boa d.çrs.3) and the fourth from 1777 to 1792 (boa d.çrs.4). all four books are related to the rice paddies in pazardzhik and plovdiv. the data are almost continuous from 1688 to 1792 covering more than 100 years of changes in the allocation of paddy lots on various river branches, except for five years between 1728 and 1734. fig. 3 example of a rice tax office book from the first half of the 16th century (image courtesy of the prime ministry’s ottoman archive, istanbul, boa d.çrs.d.25994) sert 2021 / journal of environmental geography 14 (1–2), 1–14. 5 fig. 4 example of a rice paddy tax register document from the early 18th century (image courtesy of the ottoman archive, istanbul, boa d.çrs1, 29. çrs 1, 29) the data about the allocation of the paddy fields is not adequate to compare yield quantity with climate variability, since they do not offer annual accounts. despite these shortcomings, analysis of these documents may give important results about the anthropogenic intrusions on the land. when compared with the pollen data of rice in future studies, new perspectives may be gained. waqf account books one critical type of regional document may help to provide evidence of climate variability and its effect on yield: the waqf account books (vakıf muhasebe defterleri) record yearly revenues from foundation budgets. annual changes to the quantity of yield and price fluctuations are appropriate for a comparison with climate variability. however, the data are seldom continuous. methods climate variability is not the only controlling factor of rice yield variability. dry spells, changing clo ud cover (and solar radiation), wind speed, seasonality and the timing of heat stress, water scarcity, pest and pathogen infestations, agronomic challenges, and economic and political or social factors can also affect yields. among the many factors influencing rice production, yield fluctuations caused by climate variability can only be traced in high accuracy matches. this study offers a comparison of contemporary sources with regional climate data. it uses only contemporary sources that enable analysis of the change in rice yield. since there is no one -toone matching palaeoclimatology data for each plantation location, the definition of the regions is crucial to the analysis. the study defines regions which show similar climatic characteristics and uses the reconstruction of the june-july-august palmer drought severity index (jja pdsi) series of the old world drought atlas (owda) produced by cook et al. (2015). their owda reconstruction depends on data derived from tree rings and historical and archaeological data. it uses the point-by-point method, and yet, for some locations, the data’s sensitivity is weak since it uses a proxy search radius of 1,000 km around each location. all in all, for this long-term review, the single year maps and decadal mean summer precipitation values show a regional differentiation in the distribution of droughts and are useful for understanding yield decreases caused by long-term drought and consequent water scarcity in the rice growing season. rice grows and matures in approximately 150 to 200 days. seeds start to be planted as temperatures increase after april in south anatolia, in early may in thrace and in late may or early june in the north balkan peninsula. during the first 60 days, at the vegetative stage of germination, seedling and tillering, scorching temperatures and water deficits are detrimental to growth. the ideal temperature for germination is 20–35 °c (maclean et al., 2013). water scarcity in the crop-growing season reduces yield (altinsoy et al. 2013) and the need for water in june and july increases, thus the reduced depths of water in rice fields decreased yield (kara et al. 2013). decadal droughts may cause water scarcity and lead to less water being allocated to the branch canals. phenological data from rice plantations in the central anatolian, black sea, mediterranean, southeastern anatolian, southeastern european and marmara transition regions will be compared with the reconstructed owda summer precipitation data (cook et al. 2015), temperature changes and weather extremes. important changes to the organization of plantations from decrees and revenue changes from cadasters offer partial comparison. available yearly records of yield and rice price data in waqf account books provide year on year changes. results central anatolia, the black sea region, the mediterranean, southeastern anatolia, southeastern europe and marmara transition regions show dissimilar climatic characteristics. for each region, changes in summer pdsi values are indicated with yellow boxes and periods when the summer pdsi extremes increased with blue boxes. 6 sert 2021 / journal of environmental geography 14 (1–2), 1–14. continental central anatolia in continental central anatolia, production was located in temperate lower regions (fig. 1a). three locations can be identified from archival evidence : beypazarı, konya and karaman (boa, mad.d.10249, boa, mad.d.12168, boa, mad.d.3120; coşkun 2010). although plantations in the kızılırmak and sakarya river valleys depended on irrigation, the annual mean precipitation values are very low and the region was vulnerable to decadal droughts. the tree ring-based hydroclimate reconstruction of the owda (cook et al., 2015) shows that there were extreme drought years and an important decrease in the mean summer pdsi values by the end of the 16 th century (fig. 5). the small yellow box shows a short high precipitation era in the early 16 th century. the long yellow box shows that the region had experienced a long low precipitation period, in which the mean jja pdsi values were under -1. nar lake high-resolution data confirm that there was also a dry period between ad 1400–1950 (jones et al., 2006). the change in mean summer precipitation, and the length and intensity of the drought in these years may have caused water scarcity, resulting in an overall trend toward desiccation and decreased water depth in some paddy fields. for example, in konya and karaman, active plantations existed before the end of the 16th century. the karaman pious foundations’ regional revenue book from 1483 mentions two rice grinding mills (coşkun , 2010). historical evidence from konya also shows that rice was planted there in the 16 th century (orbay, 2012). in both locations, the production of rice had decreased by the end of the century. the account books of selim ii’s and mevlânâ celâleddîn-i rûmî’s waqfs in the konya region provide some annual comparable price data (orbay, 2012). according to this data, rice was listed among both the revenues and expenditures of the foundation between 1594 and 1597; however, it had disappeared from revenues by 1597. this probably means that rice production in the lands that the foundation owned no longer returned revenues or production stopped. fig. 5 reconstructed june-july-august palmer drought severity index (pdsi) values of the owda (cook et al., 2015) for continental central anatolia between 1400–2000 table 1 rice prices in the account books of selim ii’s and mevlânâ celâleddîn-i rûmî’s foundations (orbay, 2012) and their comparison to reconstructed owda june-julyaugust palmer drought severity index (pdsi) values (cook et al., 2015) for continental central anatolia at konya between 1594 and 1602. year reconstructed jja selim ii.'s waqf mevlânâ celâleddîn-i rûmî's waqf pdsi 10-year spline revenues expenditures expenditures 1594 -1,4054 -2,257 1,73 2,6 1595 -2,8337 -2,339 2,3 3,18 1596 -3,4746 -2,301 2,3 2,59 3,23 1597 -1,5316 -2,106 3,27 3,46 1598 -1,2798 -1,834 3,76 3,56 1599 -0,7683 -1,525 4,16 4,33 1600 -3,3649 -1,125 3,62 3,75 1601 0,2699 -0,545 3,42 4,33 1602 0,4688 0,112 4,79 a comparison with the reconstructed owda summer precipitation data (cook et al., 2015) shows that this may be related to water scarcity. table 1 compares rice prices in the account books of selim ii’s and mevlânâ celâleddîn-i rûmî’s waqfs and reconstructed owda june-july-august pdsi values (cook et al., 2015) between 1594 and 1602. ten-year spline summer pdsi values point to water scarcity in 1594, 1595 and 1596. the drought intensified from 1595 to 1596 and summer precipitation values fell from pdsi -2.8337 to 3.4746. in the same years, rice prices in the revenue section of the accounting book increase from 1.73 akçes to 2.3 akçes. after 1596, the rice revenue record was no longer in use and summer precip itation values were under zero. moreover, according to the cook et al. owda reconstruction (2015), an extreme drought occurred in 1600. rice prices listed as waqf expenses increased from 2.6 akçes in 1594 to 3.42 akçes in 1601. although climate stress may not have been the only factor to cause such a price increase, this partial data shows a negative correlation between summer pdsi values and rice prices in waqfs revenues. many other factors may have been causal in this decline and the disappearance of rice revenues, but dry june -julyaugust conditions are one probable trigger for this decline, as suggested by the owda reconstruction (cook et al., 2015). this fragmentary data from the revenue records reveals little in itself about water scarcity’s effect on rice production. therefore, it is highly important to find data more appropriate for comparison. future studies may fill in the gaps and produce contin uous results. historical studies by griswold (1993) and white (2011) relate peasant rebellions in continental central anatolia to climate variability. there were also extreme fluctuations in the grain yield revenues sert 2021 / journal of environmental geography 14 (1–2), 1–14. 7 of the region’s waqfs. orbay (2012) rela tes the financial difficulties of sadreddîn-i konevî and the mevlevî waqf with june-july-august precipitation fluctuations in southwestern anatolia, as described by touchan et al. (2005). more documentary evidence from the grain yield revenue registers of the account books can provide a better understanding of the effect of the little ice age droughts in central anatolia by using palaeoclimatology data produced in the last decade. documentary evidence from the revenue books shows that northern parts of central anatolia were more active in production. the mean precipitation rates are slightly higher in the area ( fig. 1 right). according to an edict dating back to 1546, beypazarı, a town northwest of ankara, had rice fields on the sakarya catchment (boa, i̇e.ml.1/29). in 1580, a decree ordered villagers to give their tax revenue as hulled rice to bolster the halil paşa waqf’s revenue and avoid losses (boa, a.dvnsmhm.d.41/1031). a decree dating back to 26 november 1609 states that those who worked the hasan paşa waqf in beypazarı but had left their village because of bandits should not experience problems returning to beypazarı (boa, a.dvnsmhm.d.78/2104). two months later, another decree stated that new revenues from bursa and ankara should be added to the waqf’s revenues. the decree book also mentions other security problems in the region (boa, a.dvnsmhm.d.78/2104). at present, it is not possible to analyze the specific effect of the drought on the fields; production may have stopped because of bandits or drought, or both. in 1802, a decree ordered that rice from beypazarı be sent to hacı bayram-ı veli order in ankara (boa, ae.sslm.iii/197, 11831). thus, although there may have been ruptures in production by the end of the 19 th century, rice production continued in areas north of ankara. the blue box shows the period where precipitation extremes also occurred after the mid-16th century. future phenological study may provide more data about the influence of these summer extremes. according to the owda reconstruction (cook et al., 2015), the low mean summer precipitation period started at the end of the 16 th century and lasted until the late 20th century. in this four-hundred-year period, the mean precipitation rates during droughts were under -1 and the region experienced a significant change in its flora. agricultural areas also suffered subsurface water problems and high salinization, as shown by the long yellow box in figure 5. some areas are still experiencing desertification today. studying the early effects of droughts and previous conditions in the region makes the effect of climate change more evident. water scarcity will likely be the most important issue to affect the region in the future (sen et al., 2012). black sea region there were once plantations on the sakarya and yeşilırmak rivers at locations where temperatures were adequate. other rice plantations were cultivated in düzce, kastamonu, boyabad on the gökırmak river, a tributary of the sakarya river, and in amasya within the yeşilırmak river valley (b oa, ae.ssül.i.2; boa, mad.d.141; boa, mad.d.9507; boa, i̇e.ml.1/29; boa, i̇e.dh.2/109; boa, i̇e.ml.12/1035; boa, i̇e.ml.24/2327; boa, ae.smmd.iv.56/6501; boa, i̇e.ml.16/1532; boa, ae.smmd.iv.101/11751; evliya ii, 98). the annual precipitation in the black sea region is much higher than in other areas of continental central anatolia (fig. 1b). türkeş (1996) and akkemik et al. (2005) calculated 300 mm mean annual rainfall for continental central anatolia and 1,000 mm for the black sea region. the owda june-july-august pdsi values (cook et al., 2015) also show that summer droughts were less effective in the black sea region than in continental central anatolia. rice production in the black sea catchment of the sakar ya river continues to this day. historical evidence about revenue collection and security problems draws our attention to drought years and their possible impact. for example, according to the owda reconstruction (cook et al., 2015), there was a drought in 1701 and subsequent problems with the collection o f rice revenues, as recorded in march 1702 in boyabad (boa, a.dvnsmhm.d.112/6109). after the drought year of 1708, as shown by the owda reconstruction (cook et al., 2015), another revenue collection and subsequent security problem occured (boa, i̇e.şkrt.2/170). however, many other factors may play a role and better analysis would require the study of yearly yield data from the waqf account books. mediterranean coastline the west coasts of the anatolian peninsula usually receive more precipitation than continental central anatolia even in the scorching summers (fig. 1 right). rice production existed as early as 1480 in aydın on the büyük menderes river (boa, mad.d.7387). the decrease in jja pdsi after the 17 th century did not fall below zero until the end of the 20th century (fig. 6). as seen in the second yellow box, jja pdsi values declined at the end of the 16 th century. the blue box shows an increase in the extreme values and also betterment in the low precipitation that started at the end of the 16th century and continued until the mid 17th century. after this betterment of precipitation value, mean jja pdsi in the growing season did not fall below zero. however, as these data derive from the trees that lay higher in the mountains, they may not directly reflect the precipitation for lower agricultural regions. historical evidence shows that rice production was undertaken sporadically due to water scarcity. for example, in manisa, on some of the sultan’s plantations, certain fields were left unfarmed for 10–15 years (emecan, 1993). there are numerous registers, mentioning changes to tax farmer rice plantation lots. as in other locations, rice yield data may be found in single waqf account books and historical evidence about climatic extremes and their effect on plants may be documented. 8 sert 2021 / journal of environmental geography 14 (1–2), 1–14. fig. 6 june-july-august palmer drought severity index (pdsi) from the owda reconstruction (cook et al., 2015) for the mediterranean between 1400 and 2000 southeastern anatolia there were rice plantations in mardin, urfa, samsat and darende on the euphrates river (boa, ts.ma.d4391), bitlis and siirt on the tigris river (boa, mad.d.10280; evliya iii: 95, 97) and in the region between maraş and ayıntab on the aksu river (evliya iii, 100). registers were kept from 1519 about tax farmer changes in darende on the tohma river, a branch of the euphrates (boa, mad.d.15450). a decree dating back to 1595 informs about tax farmer changes in diyarbakır (boa, a.dvns.mhm.d.73/33, 81). unfortunately, the data do not include yearly yield or price data that would allow any comparison. pehlivan (2020) provides documentary evidence on animal deaths, especially in the years of drought that followed extremely cold winters in the 19th century. jja pdsi values are lower in years from the late 18th century (fig. 7). available proxy data show that there are two crucial decreased mean summer precipitation periods: one between the late 18th and early 19th centuries and a second that began in the early 20th century. moreover, the region’s summer precipitation extremes began in the middle of the 17th century, as shown within the blue box. future regional studies may provide more data about the fluctuations of rice harvests and other effects of climate variability. since proxy data from tree rings are also very rare for the region, the cook et al. 2015 owda jja pdsi mean values probably have low resolution. all in all, phenological data for this region would be very valuable. southeastern europe 15th century censuses show that the ottomans started cultivating rice in the osum and seman river deltas even when jja pdsi values were low. rice tax was mentioned among the revenues of some villages near berat, albania, as early as 1432 in the area’s first revenue registers (i̇nalcık, 1987). the seman river delta in present-day albania is favorable for building rice paddies: the area’s mean may-june-july temperatures are over 20ºc (fig. 1 left) and the yearly fig. 7 june-july-august palmer drought severity index (pdsi) from the owda reconstruction (cook et al., 2015) for southeast anatolia between 1400 and 2000 mean precipitation is high (fig. 1 right). according to cook et al. (2015), jja pdsi mean summer precipitation values were also high when the ottomans organized plantations there in the 16 th century (shown within the first yellow box in figure 8). southeastern european river valleys in macedonia, thessaly and thrace were also appropriate for rice farming. other revenue registers show that in 1516 the area between niš and pirot (in present-day serbia) and northern regions like kruševac also had rice plantations (amedosky, 2017). drought data from the owda and historical evidence show that weather extremes started in the mid -16th century and ended in the mid-18th century. during these extreme weather conditions, floods disrupted some rice paddies in the 17 th century. in lamia, floods filled the paddies with stones in 1629 and 1630 (boa, a.dvnsmhm.d.85/297). between 1714 and 1718, very severe conditions affected the paddies in thrace and, in 1716, floods ruined rice paddies on the peloponnes, causing villagers to leave their homes (amedosky, 2017). weather extremes are especially relevant to cash crops like rice and sugar cane since they require mills in their production process, which are operated using water energy or working animals that are both stressed by extreme levels of water. floods that damage mills also negatively impact rice production. rice production existed in niš before the ottomans arrived in the region, but production increased under their reign. the crop was one item among several doubling niš’ revenues from 1498 to 1516 (amedosky, 2017). temperatures fell in the 17th century (luterbacher et al., 2004) and weather extremes started mid-century. by the 18th century, some niš plantations became meadows and were used for animal farming (amedosky, 2017). on 21 february 1739, a decree ordered rice to be sent from plovdiv to niš for the army (boa, i̇e.ml.45/4373), which may indicate that production was not even enough for local use or the increased army n eeds in the region at the time. sert 2021 / journal of environmental geography 14 (1–2), 1–14. 9 fig. 8 june-july-august palmer drought severity index (pdsi) from the owda reconstruction (cook et al., 2015) for albania between 1400 and 2000 the effect of 18th century extremes changed crop preferences in the region. since rice leaches the soil and makes it suitable for other crops (maclean et al., 2013), people often substituted rice with less labour intensive corn (warman, 2003). the decline in rice production may have been due to insecurity, deteriorating workforce availability, energy problems, deteriorating climate conditions and/or the incompatibility of rice varieties. the ottomans started plantations at timișoara, the most northern-known plantation location. five decrees between 1572 and 1579 mentioned rice cultivation. the first, from 7 april 1572, regards a request for rice plantation experts (çeltikçis) ( boa, a.dvnsmhm.d.16/399; boa, a.dvnsmhm.d. 16/400). the second, from 12 september 1573, mentions a decline in revenue (boa a.dvnsmhm.d.22/683). on 25 june 1578, a decree ordered the administrators to check whether the region was appropriate for rice growing or not (boa, a.dvnsmhm.d.35/33). in the following year, problems in the collection of rice revenu es were mentioned again (boa, a.dvnsmhm.d.36/577). european summer temperatures decreased in the 17th century (luterbacher et al., 2004), which might have resulted in the reduction of rice plantations at the northern limit of the natural rice cultivation z one. historical evidence from franciscan monastery chronicles mentioned by mrgić (2011) shows that weather extremes influenced the region’s agriculture in the 17th and 18th centuries. while droughts were recorded in 1660, 1664 and from 1686 to 1687, heavy snowfall was also mentioned in 1683, 1687 –1690, 1731, 1737–38, 1741, 1743, 1749–50, 1753, 1759–60, 1762, 1764–65, 1767, and 1769–70. these extreme weather years correspond to wars (mrgić, 2011; 2018), including the long war (1593 –1606) in the western balkans, followed by the morea war (1684– 1699) in the south of the balkan peninsula and, finally, the war of the holy league (1683 –1699). weather extremes and wars decreased the workforce and caused insecurity in plantation areas. in the balkans, the number of çeltikçis had decreased by the beginning of the 18th century (kul, 2017). but, as long as the workforce was available, the canals were repaired and there were still numerous paddies producing rice throughout the century. evliya çelebi mentions serres, thessaloniki, crete, lepanto and ioannina as places where good rice was produced in the 17th century (evliya viii, 59, 73, 240 -241, 271, 289). the influence of weather extremes both on the production process at mills and agriculture would be a very important topic for future studies. marmara transition the owda reconstruction (cook et al., 2015) shows that the mean summer precipitation values in the maritsa river catchment at plovdiv were much higher than they are today. the yellow boxes in figure 9 indicate periods of change in mean summer precipitation values. according to these values, the region experienced a two-step decrease in mean summer precipitation from the early 19 th century. as a result of these gradual long-term decreases in precipitation and the high use of water sources for mass agricultural production, the region experiences significant water resource problems today. in the ottoman plovdiv, rice paddies were registered as early as 1480 (boykov et al., 2000). plovdiv and pazardzhik produced large amounts of rice (shopov, 2020). this agricultural organization for large-scale production relied on the existence of large estates. these estates that fed istanbul belonged to the waqfs of the sultans and high statesman. the organization of the workforce was the most critical factor for labour-intensive rice plantations. the number of workers known as kürekçi, involved in rice production, who were responsible for the technical organization of the canals, increased from 19 in 1480 to 55 in 1570–71 (shopov, 2020). the owda reconstruction (cook et al., 2015) shows that the mean summer precipitation values decreased by the end of the 16th century, as seen in the second yellow box in figure 9. scorching summers and water stress meant harder conditions for workers and animals, and less water for the mills. historical evidence shows that workers sometimes fled from hard working conditions in the fields and from malaria, which was rampant in rice fields. in 1583, a malaria outbreak was recorded (sert, 2020a; shopov, 2020; boa, a.dvnsmhm.d.49/137). conditions became harder by the end of the 16 th century. in 1597, some villagers could not pay their taxes and fled (boa, ae.smmd.iii.1/31). commercial production continued in eastern europe despite reduced wages and worsening labour conditions (wiesner, 2013); when workers left, new ones replaced them and production continued. migrants supplied the labourintensive workforce in the plovdiv paddies. after extreme droughts and extraordinarily cold winters in the crimean peninsula that resulted in animals and people perishing, many moved to ottoman lands in the 15th century and later in 1560 (veinstein, 2001). moreover, demographic studies (stoianovich, 1992; kiel, 1997) show that decreasing temperatures in the 17th century affected many people living in mountainous areas of the balkans who moved to lower altitude settlements like plovdiv. 10 sert 2021 / journal of environmental geography 14 (1–2), 1–14. fig. 9 june-july-august palmer drought severity index (pdsi) from the owda reconstruction (cook et al., 2015) for plovdiv between 1400 and 2000 waqf account books published by oruç et al. (2014) give a snapshot from five years between 1635 and 1641 and allows a comparison of yearly yield fluctuation with june-july-august pdsi changes. in table 2 annual rice revenue entries of the şahabeddin paşa waqf account books are compared with the june july-august pdsi values from the owda. yield amounts show a negative corr elation with owda summer precipitation values and decadal spline values. the approximate production amounts compared with june-july-august pdsi values show that pdsi values were -0.2539 in 1634, 0.0924 in 1635 and -0.6714 in 1636 and that production was approximately 456 kg (14 müd) in those years. it dropped to 391 kg (12 müd) in 1637 and 1638 when june-july-august pdsi decreased to -2.436 in 1637 and -2.2904 in 1638. there is no yield data for 1639 when the june-july-august pdsi was -1.4531. although the june-july-august pdsi was 0.9276 in 1640, ten-year spline values were still negative. after the long dry years, yield dropped to 293 kg (9 müd). in 1641, the june-july-august pdsi increased to 2.084 and yield increased to 489 kg (15 müd) (oruç et al., 2014). the same negative correlation was seen in konya. however, a long series of data is needed to fully understand the influence of climate variability. for plovdiv, other revenue books of the şehabeddin paşa waqf are available in the sofia archive for 1613–1614, 1672–1673 and 1679–1680, but the series of documents does not continue. the fluctuations of yields in other waqfs can also be a good source of information for determining climate history. quite a few waqfs had rice plantations in plovdiv. even in low precipitation years such as in 1540 (cook et al., 2015), the amount of rice carried by camel caravans from plovdiv to istanbul was around 513 tons (shopov, 2020). this means that data regarding the şahabeddin paşa waqf indicate only a very small part of the production. in future, the waqf account book series may show the relationship between yearly yield and precipitation cha nges for more extended periods. all in all, droughts have been effective. andreev et al. (2003) mention issues regarding rice revenues from 1698 to 1700 and water supply in 1708. table 2 comparison of reconstructed owda june-julyaugust palmer drought severity index (pdsi) values (cook et al., 2015) to the yield amounts according to şahabeddin paşa waqf account books (oruç et al. 2014) for the area of plovdiv. reconstructed jja crop yield year pdsi 10-year spline production in kg müd 1634 -0,2539 -0,176 456 14 1635 0,0924 -0,622 456 14 1636 -0,6714 -0,993 456 14 1637 -2,436 -1,176 391 12 1638 -2,2904 -1,04 391 12 1639 -1,4531 -0,607 1640 0,9276 -0,085 293 9 1641 2,084 0,224 489 15 moreover, historical evidence highlights the 1718 drought when villagers applied for a tax reduction and help to repair canals. however, officials declined their request and instead ordered them to pay 60 akçes for each kilo of rice they failed to deliver. people left their villages in plovdiv and pazarcık after this event (andreev et al. 2003). andreev et al. (2003) describe how the 1730s were even worse, whereby there was almost no rice revenue in 1735. this coincides with accounts of kelemen mikes (1690–1761), the famous hungarian essayist and political figure, who lived in exile with the transylvanian prince ferenc rákóczi in tekirdagh. kelemen mikes described extraordinarily hot temperatures in march 1735 (sert, 2007). as march is the germination period for rice seed and the ideal temperature for germination is 20–35ºc, scorching temperatures and water deficits would have been detrimental at this vegetative stage. this may be a reason why there were no rice revenues. kelemen mikes mentions a significantly cold spell in 1740. that year, spring came late. it was even cold in may. in addition, december of the same year was extraordinarily hot. it was as if the seasons had changed place (sert, 2007). there is a decree dating back to 27 march 1742 that includes the complaint that villagers did not seed their rice in march (boa ae.smhd.i.158/11923); since 1740’s spring was so cold and farmers lost their seed, it is possible that they were behaving cautiously. kelemen mikes also mentions a devastating amount of snow, which started in october 1751 before the harvest of cotton and grapes (sert, 2007). according to cook et al. (2015), the owda 19th century mean summer precipitation values fell and extreme drought years were experienced in 1806, 1830, 1832–1834, 1840, 1851, 1861–1863, 1887 and 1893– 1894 (fig. 9). droughts probably made working conditions harder. in may 1844, the center sent help to rice workers (boa, a.mkt.12/13, 01). before this date, all relevant records refer to the punishment of workers who fled or peasants who did not pay their sert 2021 / journal of environmental geography 14 (1–2), 1–14. 11 taxes. perhaps conditions were more demanding and the workforce had diminished to such an extent after the long balkan wars that state authorities realized coercion might not work this time. this is the first mention of help being sent to workers so far identified by this study. in the course of the 19 th century, the ottoman empire lost its plantations in the balkans. the supply of rice decreased so much that demand in the ottoman market could only be met with imported rice (emecan, 1993). the state gave priority to resettling rice farmers who migrated from the balkans to places that were convenient for rice farming in anatolia, for example, and rice farmers from plovdiv continued rice cultivation in bursa. discussion the little ice age was the period in which mean temperatures declined by up to 2ºc. like global warming today, the change in mean temperatures meant very hot and very cold extremes, floods and extreme seasonal changes. its effects were divergent and showed regional differences. while in continental central anatolia, the little ice age brought drought years, which reduced agricultural production, and caused migration and rebellion (white, 2011), its effects on europe were asynchronous and diverse. ottoman historians have asked (griswold, 1993; orbay, 2007; sert, 2007, 2020b; white, 2011; kolovos et al., 2018; kuru, 2018) whether or not the little ice age and other climate changes influenced the ottoman empire. to answer this question, institutional changes should be first mapped and then these changes should be related to the environmental and socio -economic conditions that the institutions faced. the present study shows partial effects of climate variability on rice yields, labour relations, rice mills, the health of inhabitants and population movements. the regional variability demonstrates the importance of using appropriate palaeoclimatology data in historical studies. paleoclimatogic proxy data can advance discussions about the impact of climate variability in ottoman historiography. both the regional differences in climate variability and the influence of weather extremes are significant for discussions about the little ice age in ottoman history. the ottoman empire experienced profound institutional changes after the second half of the 16 th century (kunt, 1983; tezcan, 2010). an increase in the capacity of supplying food to cities and the capacity of intrusion into the environment draw some attention. however, the effect of climate is an underestimated topic in this anthropocentric historiography. the effects of the little ice age have been introduced as a trigger for the decline of the ottoman empire (white, 2011) but have never been examined as a factor for institutional advancement even when the decline theory was rejected. the little ice age droughts, which started at the end of the 16th century and continuing into the 17th century, were destructive in central anatolia. due to the teleconnections of climate, an east-west bipolar climate seesaw operated in the mediterranean. while inner anatolia was dry, west europe and western anatolia had higher precipitation rates (roberts et al., 2012). while in continental anatolia the little ice age brought drought years, which decreased agricultural production and caused migration and rebellion in the 17th century (white, 2011), the aegean islands and southern balkans saw an increase in the olive harvest during the very same century (kolovos et al., 2018). likewise, in the coastal regions of anatolia, where climate conditions were different, population movements and production conditions were not like those in central anatolia (kuru, 2018). due to these conflicting conditions, ottoman scholars have discussed whether the little ice age was effective on the ottoman empire at all. the present study asserts that a better acquaintance of the ottomanist with palaeoclimatology data is vital to understand the teleconnections of climate and society. instead of focusing only on the destructive effects of the little ice age, recognizing its institutional challenges may overcome dualistic discourse in this scholarly discussion. orbay (2007) shows that waqfs undertook important institutional transformations to overcome the problems caused by increased food prices (e.g., waqfs introduced cash aid to students instead of providing free food from their kitchens). he highlights regional differences in the transportation of food from other regions, exemption of tax revenues and refutes the idea that the 17th century was a crisis era triggered by climate change that led to the empire’s decline. although i agree with orbay (2007) about the importance of institutional measures and organizational changes and agree with kolovos et al. (2018) and kuru (2018) that climate conditions were different in other regions, there was a regional crisis in central anatolia that started at the end of the 16 th century and continued during the 17 th century. moreover, the effects of the little ice age in the balkans still needs to be studied, especially as this study and mrgić (2018) show that the 18 th century climate extremes influenced the region. moreover, the effect of 19th century droughts were more influential than the 16th century in istanbul (sert, 2020b). conclusion this study has introduced the importance of ottoman rice plantations in the environmental reconstruction of the region between the tigris and the danube. it has classified available archival documents about plantations and compared palaeoclimatology data with archival evidence. this comparison shows partial historical evidence about the effects of precipitation and temperature variability and climate extremes on rice yields and the research potential of ottoman archival documents for climate history. results show that decadal low summer pdsi values coincided with a decrease in rice yields or an increase in rice prices in plovdiv and central anatolia. weather extremes such as the cold may in 1740 resulted in a fatal decrease in yield in plovdiv. the piecemeal information about the effects of climate 12 sert 2021 / journal of environmental geography 14 (1–2), 1–14. variability prove that the account books of waqfs are an important source type that can give yearly yield data. nature provides useful evidence to help understand the archives of societies (white et. al, 2018). questions about the influence of the little ice age on the ottoman empire will find answers in line with an increase in palaeoclimatology data. in 2007, when orbay (2007) was writing about grain yields and climate relation, available palaeoclimatology proxy data was limited. future works on account books may answer some of the questions raised here if prices and yearly revenues are compared with palaeoclimatology proxy data. moreover, a group of scholars in paleo science and history at the max planck institute for the science of human history in jena, including ottomanists georgios liakopoulus and elias kolovos, are working on phenological data about grain to reveal information about the relation between climate and institutional changes. the present study aims to contribute to the debate. acknowledgement i would like to thank onur i̇nal, florian riedler and yavuz köse for their comments and suggestions on earlier versions of this article. i want to express my gratitude to andrea kiss, zeki bora ön, ozan mert göktürk, adam izdebsky and georgious liakopoulus for their support and guidance regarding climate history. zeki bora ön, maya gül sandfuchs and haluk zelef gave their precious time to help me develop my figures. elçin arabacı shared valuable data about bursa. kayhan orbay discussed climate influence and lia since 2007. an ottoman database for climate events was planned with him and günhan börekçi. i thank umut soysal for his guidance on the diplomatic features of rice tax office books (çeltik rüsumu kalemi). i am greatful to sarah waring, whose thorough editing has helped me express my ideas more precisely. i also thank nurten akarsu for her support. i am grateful to two institutions: the research council of hacettepe university, which supported my studies at vienna university for three months, and the department of near eastern studies of vienna university, which hosted my project for one year. references ágoston, g. 2009. where environmental and frontier studies meet: rivers, forests, marshes, and fortifications along the ottoman-hapsburg frontier in hungary. in: peacock, a. 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(ed.) osmanlı i̇mparatorluğu’nda doğal afetler. tarih vakfı yurt yayınları, i̇stanbul, 297–306. venzke, m. l. 1992. rice cultivation in the plain of antioch in the 16th century: the ottoman fiscal practice. archivum ottomanicum 12, 175–276. warman, a. 2003. corn and capitalism: how a botanical bastard grew to global dominance. university of no rth carolina press, chapel hill watson, a.m. 1981. a medieval green revolution: new crops and farming techniques in the early islamic world. in: udovitch, a.l. (ed.) the islamic middle east, 700-1900: studies in economic and social history (princeton studies on the near east). darwin press, princeton, nj, 29–58. wessel, p., luis, j.f., uieda, l., scharroo, r., wobbe, f., smith, w.h.f., tian, d. 2019. the generic mapping tools version 6. geochemistry, geophysics, geosystems 20, 5556–5564. doi: 10.1029/2019gc008515 white, s., pfister, c., mauelshagen, f. 2018. the palgrave handbook of climate history. palgrave macmillan uk, london white, s. 2011. the climate of rebellion in the early modern ottoman empire. cambridge university press, cambridge wiesner, m. 2013. early modern europe, 1450 –1789. cambridge university press, cambridge introduction study area anatolia the balkans data and terminology decrees cadastres rice tax office books rice paddy tax register documents waqf account books methods results continental central anatolia black sea region mediterranean coastline southeastern anatolia southeastern europe marmara transition discussion conclusion acknowledgement references journal of environmental geography journal of environmental geography 6 (3–4), 31–37. doi: 10.2478/jengeo-2013-0004 issn: 2060-467x inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain károly barta * department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: barta@geo.u-szeged.hu research article, received 2 february 2013, accepted 5 june 2013 abstract the research investigated the process of excess water formation. complex measurement stations were developed in order to determine the most important hydro-meteorological and soil factors contributing to the formation of excess water. the stations measure the amount of precipitation, evapotranspiration, evaporation from water surface, soil moisture in 3 different depths; soil temperature in 5 different depths; furthermore, soil water level. the study area is located in the southeastern part of hungary, near szeged, in the flood plain of tisza and maros with extremely clayey soils. the former soil data were completed by new soil survey to determine several soil parameters (e.g. bulk density, porosity, field capacity, saturated hydraulic conductivity). infiltration was calculated from the measured parameters and water budget elements of bigger rainfall event were analyzed between march 2010 and august 2011. genetic types of excess water can be separated based on the data. keywords: excess water, infiltration, water budget, soil introduction the two most frequent type of inland excess water formation are the upwelling (or vertical) type (due to the increasing groundwater table) and the accumulative (or horizontal) type (the water accumulates under gravity in the lowest areas due to limited infiltration and/or runoff, independent from the groundwater table or communicating by capillary system). this type of inland excess water is often caused by inadequate agrotechnic methods which can lead to soil structure degradation, e.g. soil compaction. these degradation processes can be noticeable all over the world where you can find any agricultural activities. based on data of jrc ies (joint research centre institute for environment and sustainability, ispra) the soil compaction affects 94 million ha only in europe, almost 10% of the continent. several studies deal with this problem (hamza and anderson, 2005; ndiaye et al., 2007) mentioned both the effects of agricultural machines and overgrazing as well. clayey soils are particularly sensitive to compaction that can step up the probability of inland excess water (birkás, 2011; birkás et al., 2009). in the last years a lot of methods were developed to determine the spatial extent of inland excess water hazard, as a result of which maps with small spatial resolution were born (thyll and bíró, 1999; körösparti et al., 2009). there is an increased need in humid years for a detailed projection of the extent and location of inland excess water formation in a better resolution. the projection and the monitoring require an elevation model of high resolution and the exact data of groundwater level. furthermore, the projection of accumulative inland excess water needs the monitoring of water budget parameters (precipitation, infiltration, evapotranspiration, soil moisture etc.) in a high spatial resolution apart from the knowledge about the basic soil parameters. a complex monitoring system was developed firstly to get detailed knowledge about the formation of the phenomenon, furthermore, to project the future inundations based on the measured data series. a further question was if the method is able to distinguish the upwelling and accumulative types, and to determine the weight of the affecting factors in the formation of groundwater and the rise of the groundwater table (the role of local infiltration, vertical groundwater flow, soil frost etc.). the method was tested on study areas in the marosszög microregion. the paper focuses on the technical and methodological development of the monitoring system and the results of the monitoring. technical parameters of the measurement stations the complex measuring unit was set up using 1 precipitation measuring unit, 2 lysimeters, 1 soil temperature measuring unit, 3 soil moisture measuring unit and 1 groundwater-table measuring unit. 32 barta (2013) the certain units are determined by the following parameters:  precipitation measuring unit: the precipitation is measured with 0.1 mm precision by reed switch and buckets.  lysimeters: the equipments work as weighting lysimeters; pvc trays of 20 cm diameter and 5 cm depth are connected to the scales. in one of the equipment, undisturbed soil monolith with vegetation is placed, the other is filled by water. the former one measures the evaporation of the vegetation of the sampled area (usually crops or meadows), the latter is able to simulate the eva poration of opened water surfaces (and excess water inundations). the weight loss on the scales refers to the evaporation that is counted by the measured data in mass unit compared to the surface of the trays.  soil temperature measuring unit: a tube of 50 c m that measures the temperature of the soil in 5 different depths. this unit measures the temperature profile of the soil. its importance increases in winter and early spring time when the formation or the termination of a soil frost can be monitored.  soil moisture measuring unit: tdr soil moisture meters are used that are able to measure over not only the field capacity, but around saturation with a reliable precision. with this method the depth of infiltration can be monitored, the capacity of water intake can be calculated from the unsaturation of the soil, furthermore, the detection of a soil layer, where soil moisture is below the moisture of the capillary zone around the groundwater table and the soil moisture of the (almost-saturated) near-surface layers. the latter has a crucial role in the formation of the accumulative type of inland excess water. the changes in the soil moisture make the estimation of the infiltrated water in mm possible.  groundwater-table measuring unit: dataqua measuring sensors are implemented to control the level of the groundwater. the exact groundwater data levels control the independence of inland excess water formation from the groundwater. the sensors measure in an hour interval, and the measured data are transferred to a central server by gprs connection. the data of the measurement stations are managed online and delivered to pc-s in .xls format. study area and methods two measurement stations were set up in the inundated areas between the tisza and maros in maroslele settlement. measurement station 1 was installed in a meadow called tápai-rét, measurement station 2 is located westwards from batida to monitor an area determined by accumulative inland excess water (fig. 1-2). the investigated areas are located at the boundary of the microregions south-tisza-valley and marosszög. it is a lowly elevated backswamp area around 78-85 m a. s. l. with an extremely variable precipitation around 530-570 mm/year (dövényi, 2010). the subsoil horizons are the recent sediments of maros and tisza, determined by clay, sandy or silty clay, only the ancient point bars are determined by coarser fractions. the mechanical composition of the upper 50-90 cm of the soils became more extreme due to the soil formation, as a result of which a low permeability layer formed, promoting the formation of inland excess waters. the characteristic soil types are humic fluvisols and gleysols, in some places vertisols, on highly elevated areas solonetz soils occur (agrotopo, 1985-86). the relief of the area is small; due to the fluvial origin remnants, point bars occur in the mostly plain area. in the backswamp areas many close depressions of high extent occur that contribute to the formation of accumulative inland excess water. these factors are further strengthened by anthropogenic facilities: roads covered by asphalt, dirt roads and the levees along the channels (kozák, 2011). fig. 1 measurement stations in marosszög (2t: tápai-rét, 3t: batida). other marks show the other soil sampling points databases and detailed soil measurements were used for the allocation of the measurement stations. the characteristic soil/sediment layers were sampled in a 2 m depth. the main soil parameters (ph, soil plasticity according to arany, carbonate-, saltand humus content) and the particle size distribution were measured. in case of the compacted layers (b horizon or plough pan layer) bulk density, porosity, field capacity, actual soil moisture and saturated hydraulic conductivity were determined from undisturbed samples. based on the particle size distribution, the bulk density and the humus content the characteristic pf values (pf 0; 2.5; 4.2; 6.2) and saturated hydraulic conductivity were determined using pedotransfer functions. inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain 33 the water surplus on the soil surface can be calculated from the measured and calculated parameters using the following water regime function: r = p – et – i where: r: water surplus (mm) p: measured precipitation (mm) et: evapotranspiration (mm) i: infiltration (mm) (generally calculated from the saturated hydraulic conductivity of the soil horizon with the lowest water infiltration capacity, however, the changes in the soil moisture give more exact estimations from the infiltrating precipitation) these point measurements can be extended only until the soil patch of the measurement stations, further values of i have to be estimated by using available soil maps. in spring and summer of 2010 a more detailed pattern of precipitation measurements would have been needed due to the spatial distribution of weather events (rainstorms, thunderstorms etc.), thus, the measured data of the dike-reeve’s houses were implemented in the estimation of the spatial pattern of precipitation. the calculated water surplus map using the data series of the measurement stations and the digital elevation model of the area allows the projection of the occurrence and extent of the inundations. although, measurements are made in every hour, due to the temporal dynamics of the process, the method can be used only in the autumn and winter period with low evapotranspiration, and only in areas where almost impermeable (clayey) soil horizons can be found near the surface. in other cases, the spatial projection of the accumulation process will have significant errors. data series between march 2010 and august 2011 were used. due to technical problems, evapotranspiration data are available for short intervals, thus, the water regime calculations are made only for low-temperature-periods. results analysis of the soil parameters the most relevant soil parameters effecting the formation of inland excess water were analysed. using former results of soil measurement, 9 soil profile were investigated altogether. the number of the analysed points was not enough to compile a detailed soil map, however it allowed to outline the overall description of the area. heavy, non-calcic clay and clay loam soil are characteristic. salt content of these soils are not signifi fig. 2 installation of the measurement stations 34 barta (2013) cant, only in the deeper layers was detected more than 0.05% salt content. the humus content of the top-soil varied between 1 and 2% in the samples. the soil forming alluvial sediments are characterised by high clay content and low carbonate content in the analysed profile. the only exception is the batida area, where loess also occurs under the young sediments. in most of the soil profiles there is a compacted layer, considering as impermeable, which affects the water management properties of the soil (table 1). there were only a few soil samples, which water permeability was better than 10 -9 m/s. the evolution of this extreme low water permeability was caused by the extreme soil texture and also by the degrading effect (compaction, texture degradation) of the tillage and the inadequate cultivation technics. these soil properties have important effect on inland water formation, because only a small part of the area is suitable for infiltration. thus probably the inland excess waters are accumulative type in this area and water can be infiltrated to the ground water on areas where the soils have the better water permeability, on the so-called “hydrological windows”, and the water increase the level of the ground water table delayed. beside these good water permeability soils, the ground water level is controlled by the adjacent tisza river and the drainage channel network. on the basis of the analysis, in the batida area and in the tápai-rét area the water permeability is very low, thus the ‘i’ parameter in the water regime function can considered as 0, practically. nevertheless, at intensive precipitation events few mm infiltrations can be detected, on the basis of the measurement dataset. analysis of data series of the complex measuring station soil moisture and groundwater table data are compared in three different depths in case of both measuring stations to analyse the relation of infiltration and groundwater – excess water. the measured data confirmed the previous experiences. in case of tápai-rét study area, only excess water inundations of groundwater origin occurred in the investigated 1.5 year-period. in case of batida study area, accumulative inland excess water was found in spring 2010 (fig. 3). here, the groundwater table was below 2.5 m at the time of the installation, because the measuring station is located on a 40-50 cm higher elevation compared to its environment, where continuous inundations were observed from autumn 2009. the soil moisture decreased from up to down, thus the infiltrating water surplus hardly reached the 35 cm depth, confirming the presence of the accumulative inland excess water. during the spring 2010, the table 1 characteristic soil parameters of the study area (perneki, 2010; galbács, 2011) a: soil sample, ka: plasticity index according to arany, tft: bulk density, p: porosity, vksz: field capacity, f: saturated hydraulic conductivity a b c (g/cm 3 ) d (v/v%) e (v/v%) f (m/s) 2007_1t/50-70 cm 51 1.67 37.2 17.1 1.20e-08 pz/0-30 cm 60 1.55 40.4 17.0 1.60e-06 1t/50-70 cm 51 1.67 37.2 34.8 1.20e-08 2t/50-55 cm 63 1.61 28.4 21.5 8.00e-10 3t/0-40 cm 50 1.65 37.9 33.9 6.00e-09 4t/50-55 cm 81 1.46 31.8 24.3 9.00e-10 5t/55-60 cm 61 1.65 32.4 24.3 9.00e-10 6t/50-55 cm 95 1.32 31.2 22.8 9.00e-10 fig. 3 1.5-year-long data series from batida measurement station a: soil moisture in depths 10, 35 and 70 cm (v/v%), b: soil water level below surface (m) inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain 35 increase of the groundwater table was not due to the locally infiltrating water surplus, but the hydrological windows of higher water infiltration capacity in higher distances. later, due to the humid spring of 2010, the groundwater level was increasing above 1 m below surface for summer, and helped the soil being saturated by the capillary rise. in autumn, the groundwater was decreasing again and the former situation occurred again. after the intensive precipitation of 1 st december, the accumulative inland excess water and groundwater level has reached each other. only the changes of soil moisture due to the precipitation was involved in the calculation of infiltration, thus, the march-april in 2010 and october-november in 2010 were taken into consideration, when groundwater-table was deep enough not to influence the soil moisture by the capillary rise (fig. 3). the more significant precipitation events, the temperature values influencing evapotranspiration and the increase of the soil moisture in the depths of 10 and 35 cm were selected (the effect of the precipitation events can not be detected in 70 cm depth). the moisture content of the soil is shown to be the most important influencing factor of infiltration among the affecting factors. the spring precipitation events were determined by lower precipitation, small evapotranspiration, but no infiltration occurred (table 2). on the contrary, in case of early autumn precipitation events, infiltration was high in spite of the warmer weather conditions due to the low values of soil moisture (below 15-20 v/v%). thus, due to the increased water infiltration capacity of the soil, accompanying by soil cracking due to the dryingout of the surface, rapid infiltration of water occurs. when precipitation events are taken into consideration from march until november (191 mm), the infiltration of 64 mm occurred. if the precipitation, fallen below 10°c temperature, is regarded (40 mm), only 7 mm got into 10 cm depth, thus, by minimal evapotranspiration approx. 31 mm water surplus formed, meaning more than 300 m 3 potential inland excess water in every hectacres. in case of the study area tápai-rét, the inland excess water originated from groundwater in the whole investigation period. it is confirmed by the fact that inland excess water formation was not found when the groundwater-table decreased below 70 cm (2010 autumn, from may 2011). therefore, infiltration can be concluded from soil moisture data series only in dry periods. table 3 confirms that capillary rise plays an important role in the alteration of soil moisture, since the calculated data from soil moisture changes resulted in the same or higher estimated infiltration than the total precipitation amount. in case of tápai-rét study area, a synergistic effect can also be observed. due to the closeness of tisza and maros, the waters also influence the table 2 the most important rainfall events in batida rq: precipitation, t: temperature, ∆sm1, ∆sm2: soil moisture growth in depths 10 and 20 cm, i: infiltration rate * the high value is caused by capillary lifting date rq (mm) t ( 0 c) ∆sm1 (v/v%) ∆sm2 (v/v%) i (mm) 11.03.2010 8.9 0.5 0 31.03.2010 7 8-9 0 05.04.2010 6.6 9.5 0 19.04.2010 15.4 10-11 0 10.09. 2010 37.6 17-18 15 5.5 36 16.09.2010 35.8 14-15 3.5 2 11 06.10.2010 41.6 11-12 5 10 16-20.10.2010 20.6 9-10 0 25-28.11.2010 17.1 3-5 2 1.5 7 01-02.12.2010 39.9 2-3 8.5 14.5 46 mm* table 3 calculated infiltration from soil moisture changes in tápai-rét, 2010 rq: precipitation, ∆sm1, ∆sm2: soil moisture growth in depths 10 and 20 cm, i: infiltration rate date rq (mm) ∆sm1 (v/v%) ∆sm2 (v/v%) i (mm) 21-22.06.2010 12 6 5.5 11.5 03.07.2010 34.3 11 9 20 28.07.2010 17 5.5 6.5 12 06.08.2010 12 5 6.5 11.5 30-31.08.2010 15.1 8 16.5 24.5 10.09.2010 27.2 11 12 23 19.09.2010 20.4 12.5 11 23.5 36 barta (2013) groundwater-level. the previous correlation analyses confirm this additional effect only above a certain water level. however, further statistical analysis is required to determine the characteristic of the relation. in the investigated 1.5-year-long period, no soil frost was detected. discussion differentiation of the upwelling (or vertical) type (due to the increasing groundwater table) and the accumulative (or horizontal) type (the water accumulates under gravity in the lowest areas due to limited infiltration and/or runoff, independent from the groundwater table or communicating by capillary system) of inland excess water important not only in scientific point of view, however because they demand different prevention and protection strategies. the accumulative (or horizontal) type of inland excess water is mainly topographic and agro technological problem, while upwelling (or vertical) type of inland excess water is more difficult problem and it can only be managed by ground water level decrease on large area, meaning large amount of water should be transported and/or stored (kozák, 2003). on the basis of the soil analysis the studied area is susceptible for the formation of accumulative) type inland excess water, but in very humid periods the ground water table can increase to the level of the surface. the dataset of the vertical and temporal changes of the soil moisture and the changes of ground water level, collected by the measurement station enables to clearly differentiate the two type of inland excess water. on the batida study area, the formation ‘pure’ accumulative type inland excess water could be analysed and the results show that the soil parameters had positive feedback on the inland excess water formation. at the time of the huge autumn precipitation and spring precipitation (snow melt) the soil become nearly impermeable, the gravitational pore volume is extremely decrease and exactly the same time when more infiltration capacity is needed due to the low evapotranspitation the soil retail the total surface water. however in summer periods, when the evapotranspiration is higher and decrease the potential of inland excess water formation, the dry soil has higher infiltration capacity. in this case the inland excess water formation can be delayed by better agrotechnics, which increasing the water holding and infiltration capacity of the soils (birkás 2011), while the prediction of inland excess water occurrence can be achieved by continuous monitoring of the soil moisture in several depth. by the presented measurement stations, the amount of inland excess water on an exact location can be estimated. by the integration of these point measurements and a high resolution elevation model, the prediction of the real inland excess water inundation would be the next step in the research. summary the aim of the research was to investigate the formation of inland excess water in detail. a complex station for the monitoring of the hydro-meteorological and pedological factors influencing the formation of inland excess water was developed, which measures the precipitation, the evapotranspiration of the soil surface and opened water surfaces, the soil moisture in 3 different depths and the soil temperature in 5 depths. the study area was allocated the back-swamp area at high inland excess water hazard in the micro-regions of the south-tiszavalley and marosszög, northeast from szeged. from the measured data, the estimation of infiltrating water was highlighted. furthermore, soil samplings were repeated in the neighbouring areas, where pedological parameters (ph, soil plasticity according to arany, carbonate-, salt and humus content), and characteristic water regime parameters (bulk density, porosity, field capacity, hydraulic water conductivity) were determined. the results described an area where due to the low elevation and the extreme particle size distribution, accumulative and upwelling-type inland excess water (of groundwater origin) both occur. the developed stations were able to differentiate the two types of inland excess water, furthermore in case of the accumulative type, the rate and temporal progress of infiltration, its extreme values in relation to soil saturation were estimated. the accumulation of potential inland excess water, the formation of the inundations can be determined by the detailed digital elevation and runoff models. acknowledgements this research was supported by the ipa cross-border cooperation programme of the european union under the project husrb/1002/121/088 meriexwa entitled, measurement, monitoring, management and risk assessment of inland excess water in south-east hungary and north serbia (using remotely sensed data and spatial data infrastructure) references agrotopgráfia map series, sheet 27, 1985-86 birkás m. 2011. a klímaváltozás hatása a növénytermesztési gyakorlatra. 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(drainage of inland excess water inundations in the great hungarian plain) hidrológiai közlöny 83 (1), 51–61. inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain 37 kozák, p. 2011. belvízi jelenségek az alsó-tiszai vízgyűjtőkön az 1955-2010 közötti időszakban. (inland excess water inundations on the lower-tisza catchments between 1955 and 2010) in. rakonczai, j. (ed.): környezeti változások és az alföld. a nagyalföld alapítvány kötetei 7. békéscsaba, 127–136. körösparti, j., bozán, cs., pásztor, l., kozák, p., kuti, l., pálfai, i. 2009. gis alapú belvíz-veszélyeztetettségi térképezés a délalföldön (gis-based inalnd excess water hazard mapping in the southern part of the great hungarian plain). magyar hidrológiai társaság xxvii. vándorgyűlése. konferencia proceedings cd-rom (isbn 978-963-8172-23-5). 2009. július 1-3., miskolc, 1–14. ndiaye, b., molénat, j., hallaire, v., gascuel, c., hamon, y., 2007. effects of agricultural practices on hydraulic properties and water movement in soils in brittany (france). soil & tillage research 93, 251–263. perneki, z., 2010. talajdegradáció belvízfoltok alatt (soil degradation below excess water inundations). master theses. szeged. 35 p. thyll, sz., bíró, t. 1999. a belvíz-veszélyeztetettség térképezése (mapping of inland excess water inundations). vízügyi közlemények 81 (4), 709–718. journal of environmental geography journal of environmental geography 7 (1–2), 23–28. doi: 10.2478/jengeo-2014-0003 issn: 2060-467x sediment dynamics in a small, 2 nd order urban river awba catchment, ibadan, nigeria aderemi adediji 1* , olutoyin a. fashae 2 1 department of geography, obafemi awolowo university, faculty of social sciences, 20005 ile-ife, nigeria 2 department of geography, university of ibadan, faculty of social sciences, 200284 ibadan, nigeria *corresponding author, e-mail: remiadediji2003@yahoo.co.uk research article, received 02 february 2014, accepted 06 march 2014 abstract the sediment dynamics in a small 2 nd order catchment of river awba in the territory of the university of ibadan, nigeria was investigated between january and december 2012. the river was gauged by daily measurements of water level as well as sampling of water for determination of suspended sediment load. in this regard, apart from weekly sample, twelve (12) storm flow events which occurred during the day were sampled for determination of suspended sediment concentration. the results showed that during the storms the suspended sediment concentration varied between 636 mg/l in may and 3641.5 mg/l in september, with a mean of 2136.8 mg/l. also, the value of monthly suspended sediment yield ranged from 10.85 kg in january to 288.4 kg in october with a mean of 89.5 kg. the variability in monthly sediment load closely followed the trend of monthly rainfall in the study area. however, in order to minimize the storm runoff and sediment load generated from the rainstorms events, the paved surfaces within the study catchment should be grassed with the planting of some few tree species. this could further reduce the rate of floods occurrence. keywords: gauged, suspended sediment, rainfall, river awba catchment introduction sediment yield is an indication of soil erosion in the river catchments. it comprises of both suspended and dissolved load discharge through the basin outlet. these materials (both suspended and solute load) are generated from both interfluvial areas and channel subsystems within the drainage basin. for instance, mwamba and torres (2009) in united states, stated that rivers are the major source of ocean sediment, and the coastal and marine environment is the ult imate sink for most fluvial systems. thus, it might seem likely that significant changes in erosion or sediment transport within the drainage basin would be reflected in the changes in sediment delivery in coastal and marine environment. however, the link between sediment dynamics within a fluvial system and sediment load at the river outlet is not always strong or direct. this is because storage opportunities or time lags may make some drainage basins/catchments, slowly responsive or relatively unr esponsive to environmental change. however, the amount of material or sediment generated and transported from the basin depends on both physi ographic and catchment characteristics such as climate (rai nfall), vegetation/land use condition, slope factor, basin area, relief ratio, drainage density and sinuosity index. in this regard a lot of published studies exist on factors influencing catchment sediment yield in both tropical and extra tropical regions (e.g. smets et al ., 2008; peng, 2008 in united states; bracken and kir kby, 2005; nadal and reques, 2008; nadal et al., 2008; noenu et al., 2010; fang et al., 2012; nu-fang et al., 2012; taguas et al., 2013 in spain; lopez et al., 2010 in italy; wei et al., 2007; zeng et al., 2008 in china; adriana et al., 2012 in france; ogunkoya, 1980; ogunkoya and jeje, 1987; oluwatimilehin, 1991; jeje et al., 1999; adediji and jeje, 2004; adediji et al., 2013 in southwestern nigeria). for example, slattery and phillips (2010) in central spain observed that land use changes determine the spatial and temporal evol ution of plant cover, which directly infl uences trends in water resources, soil erosion and conservation. according to them, changes in land use especially in terms of vegetation composition will bring about changes in sediment production in the watershed. also, nadal et al. (2008) observed that a small catc hment in a badland area of relatively humid enviro nments (mediterranean areas) shows highly active processes of physical and chemical weathering related to seasonal variations in moisture (rainfall) and te mperature. bracken and kirkby (2005) in two semi -arid catchments of southeast spain showed that a storm event on 20th june 2002 of 83.0mm was responsible for a maximum runoff depth of 12cm and a maximum hillslope sediment transport of 1886 cm 3 /m which suggested that measured sediment transport is related to runoff. in the hilly areas of loess plateau, north china, zheng et al. (2008) observed that the mean sediment concentration tends to be stable for large flood events, suggesting a strong similarity b etween surface flow-sediment relationships at inter and intra24 adediji and fashae (2014) event temporal scales. however, wei et al. (2007) also in the semi-arid loess hilly area in china observed that the processes of runoff and sediment/soil loss are complicated and uncertain with the interaction of rai nfall and land use which is due mainly to different sta ges of vegetation succession. adriana et al. (2012) in south western france observed that grass strips along rivers and ditches prevented soil sediments from entering the surface water but did not reduce soil losses and that crop redistribution within the catchment was as efficient as planting grass strips. other studies especially in nigeria, have also examined the effects of both rainfall characteristics and land use/vegetation on sediment dynamics of 3rd order catchments in southwestern nigeria. in this regard, apart from adediji and jeje (2004)’s work, there is little or no known studies on sediment yield dynamics from either the 1 st or 2 nd order basin in southwestern nigeria in particular and in nigeria as a whole. hence, this study will attempt to relate rainfall to sediment yield dynamics in a 2 nd order urbanized catchment in the university of ibadan, ibadan, oyo state, southwestern nigeria. the 1 st and 2 nd order basins are ideal for the study of hydrological r esponse pattern because they are relatively small and have homogenous physiographic and land use/vegetation attributes (adediji and jej e, 2004). more importantly they can respond very quickly to rainfall events in the form of storm-flow as well as to drought in sparsely vegetated areas (e.g. urbanized catchments). hence, the main objective of this study is to relate rainfall to sediment production from a 2 nd order stream draining through the built up part of university of ibadan estate. this study will fu rther advance the research frontier on aspect of sed iment dynamics from a small urbanized river catchment in this part of the world. study area river awba, a 2 nd order river catchment within the estate of the university of ibadan, ibadan, nigeria constitutes the study area. the study ri ver basin is between latitudes 7 o 25’58” and 7 o 26’42” and longitudes 3 o 53’21” and 3 o 54’26” east of greenwich meridian (fig. 1). the drainage area is 2.08 km 2 , its drainage density is 1.93 km/km 2 . river awba drains through a part of the academic area of the university especially the faculties of science and social sciences as well as departments of petroleum and agr icultural engineering, and emptied its water into un iversity dam/reservoir that is very close to the zo ological garden of the university ( fig. 1) the dam on r. oba at the university has been silted up and overgrown by hydrophytes such as ferns and water weeds among which are pistia stratiotes, scirpus cubensis and rhnchospora corymbosa. other common plants around the dam include lemna spp; wolffia arrhiza, nymphaea spp; and ipomoea aquatica. specifically, these water weeds have virtually completely col onized the surface area of the reservoir. because, the study stream basin is mostly built-up, it usually experiences annual flooding. in fact, in august/september 2011, many properties inclu ding animals at the university zoological garden were destroyed by floods. specifically, the land use map (fig. 2) of the study area shows that paved/built-up area and the grass vegetation constitutes the largest proportion of the study catchment. other l and uses such as swamp and gallery vegetation along the stream channels covered the smaller portion of the study area. the stream basin is underlain by precambrian basement complex rocks. specifically, the area is underlain by granites, gneisses and schists (symth and fig. 1 map of the drainage basin of river awba within the university of ibadan sediment dynamics in a small, 2 nd order urban river awba catchment … 25 montgomery, 1962). it is under köppen’s af humid tropical rain forest climate. the mean annual rainfall is about 1400 mm and distributed between the months of march and october with peaks in july and september and a short dry spell in august although, thus varying from year to year in its occurrence (iloeje, 1981). the rainfall effectiveness is between 6–9 months in the year. the onset and withdrawal of rains are marked by thunderstorms accompanied by high rainfall intensity. the temperature is high and almost uniform throughout the year because of the tropical climatic conditions with mean monthly value of about 27 ° c, while daily maximum temperatures ranges b etween 25 ° c and 30 ° c depending on the location and season (iloeje, 1981). materials and methods the study river catchment was delineated from the topographical sheet of ibadan n.w. on a scale of 1:50,000. the topographic map used in this study was corrected following the methods suggested by morisawa (1957) and morgan (1971). thereafter, the drainage network of the corrected maps was then ordered using strahler’s method. subsequently, the attributes of the study basin such as basin area (a) and drainage density (dd) were determined following the method by gregory and walling (1973). land use map of the study catchment was compiled from google image of the area at 2.5 m spatial resolution. the study stream was gauged at its exit point immediately after the zoological garden. the gauging station was installed at the exit point to mon itor change in water level during the study period (from january 2012 until december 2012). the gauge reading was observed twice a day, in the morning (around 7.30 am) and in the evening (about 5.30 pm). the daily readings of the staff gauge were obtained for the study stream. also, the stream flow discharge was determined using velocity-area technique. details of the procedures involved are documented els ewhere (see oluwatimilehin, 1991; adediji, 2003). this was done at various stages/water levels and used to derive the discharge rating equation for the study stream. the discharge rating equation derived for the study catchment was expressed as: log q = 0.138 + 1.062 log h where: q = stream flow discharge (l/s) h = stage/water level (cm) the rating equation derived for the study stream was used to convert daily stage to discharge. water sample was taken weekly during the study period. however, sampling was intensified during rainy season. in this regard, the storm runoff generated from rainfall events that occurred during the day were all sampled for the determination of suspended sediment concentration. the rating curve derived was used to obtain sediment concentration for discharges for which sampling was not done. therefore, the rating curve technique was used to convert the stream flow discharge (m 3 /s) or (l/s) to sediment concentration (mg/l) (see miller, 1961; walling, 1977). determination of suspended load involved the filtration of each 100 ml stream water sample suing whatman glass fibre circles (gfc) and a vacuum pump assembly, oven drying, cooling in a desiccator and weighing the sediment residue together with filter paper. the weight of the filter paper was su bsequently subtracted to determine the weight of the residue expressed in mg/l (see oluwatimilehin, 1991; adediji, 2003). fig. 2 land use map of the river awba catchment within the university of ibadan 26 adediji and fashae (2014) rainfall data especially daily and monthly rai nfall amount between january and december 2012 was obtained from the automated weather station situated within the study catchment and under the supervision of the department of environmental and agricultural engineering, university of ibadan, ib adan, nigeria. results and discussion the result on the area extent covered by each of land uses identified and classified from the google image of the area is as shown in table 1. according to table 1, the largest proportion of the study basin is currently grass/degraded vegetation surface. this is distantly followed by built-up/paved surfaces and swamp/gallery vegetation at the exit point and along the stream channels, respectively. this further indicated that substantial portion of the study catchment is exposed to direct rain drop impact which might produce accelerated erosion as well as flooding. as evident from table 2, the values of storm sediment concentration obtained for the study urbanized stream ranged from 636 mg/l on 21 st may, 2012 to 3792 mg/l on 15 th of october, 2012 with mean value yield of 2136.8 mg/l and standard deviation of 1290.9. also, the value of storm suspended sediment yield recorded at the beginning of the rainy season especially on 4 th of april 2012 (2375 mg/l) is far higher than value recorded at the middle of the wet season on the 7 th of july 12 (648 mg/l) (see table 2). this may not be unexpected as a lot of wastes dumped into the drainage channels and bare surfaces around the students’ hostels and academic areas within the interfluvial areas of the study catchment are moved by storms runoff into the stream. table 1 areal extent (m 2 ) of the land uses classified from the google earth image of the study catchment land use areal extent (m 2 ) % of the study area built-up/paved surface 702071 33.37 swamp/gallery vegetation 243511 11.57 degraded/grass vegetation 1158453 55.06 total 2104036 100 however, with the progressive development in the bush regrowth around the study stream channel during the peak of the rainy season coupled with high rainfall interception by bush/plant cover may possibly account for relatively low sediment concentration of 648 mg/l recorded on 7 th of july, 2012. generally, the high mean suspended sediment concentration (2136.8 mg/l) obtained for the study stream may not be unexpected because of the urbanized nature of the study catchment, where the predominant grassy vegetation is trampled as footpaths and connection route to most buildings within the studied catchment. as expected the higher mean suspended sediment concentration was high because low interception, high runoff velocity, and less time for water to infiltrate to the soil. as shown in table 2, the values of storm sediment concentrations compared favourably with the results obtained from urbanized catchments in the same general area of south-western nigeria and other parts of the humid tropical region (e.g. oyegun, 1980 in ibadan northeast (upper ogunpa); adediji and jeje, 2004 in ile-ife; jimoh, 2005 in ilorin, southwestern nigeria; pushparajah, 1985 in thailand). for instance, the maximum sediment concentration (3792 mg/l) obtained for the study stream, though higher but compared favourably with the storm sediment concentration of 3475.55 mg/l recorded by adediji and jeje (2004) from an urbanized 2 nd order stream (odo-ogbe) draining oja-titun area in ile-ife, southwestern nigeria. also, the highest value obtained in this study is in accordance with the maximum value of 4780 mg/l obtained by pushparajah (1985) from huay ma feang stream (urbanized streams) in thailand during the rainy season of 1983. also, the values of maximum suspended sediment concentration obtained is in accordance with the findings by fang et al. (2011) in a small agricultural watershed of the three gorges in china where maximum storm flow sediment concentration varied from 183 to 62, 138g/m 3 with a mean suspended sediment concentration of 7962g/m 3 . further, as shown in table 2, the monthly total sediment yield for the study streams ranged from 10.85kg in january to 288.40 kg in october with the mean soil loss of 123.59 kg and standard deviation of 89.50. the monthly suspended sediment yield rose from 10.85 kg in april to 262.70 kg in july and declined to 107.58 kg in september and rose again to 288.40 kg in october and eventually decreased to 18.75 kg in december, 2012 more or less synchronously with the monthly rainfall. it is quite evident from fig. 3 and table 2 that the monthly total sediment yield closely follows the pattern of monthly rainfall. this was also in accordance with the observation made by adediji et al (1995) in ile-ife area of south-western nigeria. fig. 3 relationship between amount of rainfall (mm) and the sediment yield of the river awba catchment sediment dynamics in a small, 2 nd order urban river awba catchment … 27 table 2 rainfall events and suspended sediment concentrations of the study catchment rainfall event date rainfall amount (mm) suspended sediment load (mg/l) a,b 1 4-4-12 32.7 2375 2 20-4-12 32.7 1053 3 4-5-12 32.7 643 4 21-5-12 32.7 636 5 7-7-12 44.1 648 6 15-7-12 111.9 3308 7 16-7-12 122.7 3721 8 20-8-12 30.3 979 9 20-9-12 78.3 3641 10 25-9-12 70.9 2350 11 10-10-12 101.7 2494 12 15-10-12 154 3792 a mean suspended sediment load = 2136.8mg/l b standard deviation of suspended sediment load = 1290.9 as evident from fig. 4, the storm suspended sediment concentrations significantly related to storm flow discharge of the study stream (r = 0.71 at p = 0.01). this further confirmed the findings by nadal et al. (2008) in a small catchment with badlands in spain where significant relationships was obtained among rainfall, runoff and suspended sediment. the result obtained in this study is also in accordance with the findings of zokaib and naser (2012) in hilkot watershed of pakistan where a good relation was observed between rainfall, runoff and soil/sediment loss under different land uses. conclusions the dynamics of suspended sediment yield in a 2 nd order river awba stream within the estate of university of ibadan, ibadan, nigeria was undertaken in t his study. the study was carried out between january and december, 2012. the results showed that storm suspended sediment concentration was relatively higher at the beginning of the rainy season (2375 mg/l (4 th of april, 2012) than at the middle of wet season (648 mg/l) (7 th of july, 2012). however, the monthly suspended increases with the increase in monthly rainfall amount. for instance, the monthly sediment yield increase by 240.25 kg between january and october. the total sediment load discharged from the study river catchment was estimated at 1.48 tonnes/year which compared favourably with adediji and jeje’s (2004) findings from the same general study area (i.e. southwestern nigeria). in the light of the above, in order to minimize the rate of storm runoff and load/yield generated from rain storm events in the study area, the paved surfaces in the interfluvial areas of the study river catchment should be grassed and avoid trampling .the inclusion of rapid growing tree species will enhance the redu ction in the sediment loss into the study stream. this will subsequently minimize the rate of flood gener ation around the zoological garden of the university in the study catchment. this is in accordance with the observation made by adriana et al. (2012) in southwestern france that in order to preserve the quality of surface water as well as reduction of sediment conce ntration, the farmers should keep a minimum acreage of grass land especially in areas bordering the river channel as also required by official french regulation. acknowledgements we appreciate the sincere efforts of mr. adigun of the remote sensing laboratory of the department of geography, university of ibadan for his prompt and adequate fig. 4 relationship between suspended sediment (cs) and stream flow discharge (i/s) (q) 28 adediji and fashae (2014) measurements of the stage during the study period and also mr. olofinyo of the physical geography laboratory for analysing the sediments. references adediji, a. 2003. sediment delivery ratios in opa reservoir catchment, southwestern nigeria, unpublished ph.d thesis, department of geography, obafemi awolowo university, ile-ife, nigeria. adediji, a., jeje, l.k. 2004. channel erosion in the opa basin, southwestern nigeria. journal of environmental hydrology 12, 1–11. adediji, a, jeje, l.k., ibitoye, m.o. 2013 urban development and informal drainage patterns: gully dynamics in southwestern nigeria, applied geography 40, 90–102. doi: 10.1016/j.apgeog.2013.01.012 adriana, f, jean-christophe, p, jean-claude, m., yveg, l.b. 2012. designing management options to reduce surface runoff and sediment yield with farmers: an experiment in south-western france. journal of environmental management 96, 74–85. doi: 10.1016/j.jenvman.2011.11.001 bracken, l.j., kirkby, m.j. 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relations at different land uses. a case in hilkot watershed in pakistan. international journal of sediment research 27, 388– 393. doi: 10.1016/s1001-6279(12)60043-2 suspended sediment, phosphorus budget and trophic status of bukit merah reservoir, perak, malaysia journal of environmental geography journal of environmental geography 10 (3–4), 1–8. doi: 10.1515/jengeo-2017-0007 issn: 2060-467x suspended sediment and phosphorus budget and trophic status of bukit merah reservoir, perak, malaysia sumayyah aimi mohd najib1, wan ruslan ismail1*, mohamad adam omar1 1hydrogeomorphology research group, section of geography, school of humanities, university sains malaysia, 11800 minden, pulau pinang, malaysia *corresponding author, e-mail: wruslan@usm.my research article, received 6 april 2017, accepted 3 october 2017 abstract bukit merah reservoir (bmr) is one of the 51 impoundments in malaysia. bmr is the oldest reservoir built in the early 1900s originally to store water for irrigation, but nowadays its functions include also flood control and water supply. nowadays, it is threatened by land use change in the upper catchments and surrounding activities, which feeding eroded material and chemicals into the reservoir. suspended sediment, as well as, nutrient fluxes into bmr are becoming an increasing threat to the reservoir, as its sedimentation and eutrophication accelerate. this paper discusses our study on the bmr carried out between march 2008 and april 2009 to assess the water quality status, and to determine the sediment and total phosphorus (tp) influx into the south pool lake. an estimated amount of suspended sediment fluxes of about 2,900 t year-1 came from the north pool lake (18%) and 12,900 t year-1 from the main kurau river inlet (82% of the total input to the bmr). of these total sediment input (nearly 15,800 t) about 5,600 t (36%) of the total sediment influx was trapped in the bmr. tp influx was about 18.8 t year-1 and about 7 t (37%) was trapped in the reservoir. the amount sediment and tp stored in the bmr affect the water quality of the lake, therefore the mean trophic state of the lake is eutrophic (tsi of 54.4) related to high productivity. increasing sediment input into the reservoir has affected the reservoir volume and frequent flooding downstream of the reservoir during rainy seasons, while eutrophication has caused the lake water quality deterioration. keywords: suspended sediment, total phosphorus, eutrophication, trophic state, bukit merah reservoir introduction suspended sediment is an important source of phosphorus (p) to freshwater ecosystems including many lakes and reservoirs (wetzel, 2001). the use of fertilizers in order to increase crop yield in catchments (hart et al., 2004) can increase pressure on aquatic systems. terrestrial soils provide the parent material from which sediments are derived, and therefore the speciation of p in lake sediments may be largely governed by the p contents of the catchment soils. however, the selective erosion and transportation of eroded material with different grain sizes in overland and stream flow may alter the composition of suspended sediments related or relevant to the bulk source material. the transport of sediment-associated nutrients such as phosphorous (p) from the soil to the river network is complex, because it is influenced by many processes such as soil erosion, sediment transport, and deposition within the catchment (e.g., gburek et al., 2000). sediments can function either as sources or losses of phosphorous. sedimentary p can act as an internal load to the overlying water column for a long period (pant and reddy, 2001). total phosphorus (tp) loading resulting from watershed development has long been recognized as an important factor affecting lake trophic status (vollenweider, 1968; dillon and kirchner, 1975; canfield, 1983). the effect of excessive tp loading to shallow lakes is especially pronounced as it can lead to high macrophyte production, which on senescence contributes significant amounts of nutrients to both sediments and overlying waters (nichols and keeney, 1973; carpenter, 1980; carignan and kalff, 1982; sabah and wanganeo, 2008). lake enrichment resulting from the mobilization of tp from watersheds is often, over time, followed by internal tp loading from bottom sediments (ahlgren et al., 1988; nürnberg, 1984; nürnberg and lazerte, 2004; french and petticrew, 2007). exploration of the geochemical association and potential bioavailability of particulate p is required, since once p is introduced to lake ecosystems it will accumulate in the bottom sediments. the stored p in the sediment can be released into the overlying water under some environmental conditions, which may have a significant impact on water quality and ultimately result in continuing eutrophication (lennox, 1984; abrams and jarrell, 1995; xie et al., 2003). phosphorus release is influenced by a variety of environmental factors including water temperature, ph, phosphorus, dissolved oxygen (do), nitrate, redox potential and hydrological conditions (jensen and andersen 1992; gao et al. 2005; zhu et al., 2007). phosphorus distribution in lake sediments is not uniform over an entire lake and environmental conditions are equally variable. consequently, the release of phosphorus and the factors 2 najib et al. (2017) affecting this release is likely to vary within a lake. according to carlson (1977), the accuracy of the index values based on tp depends on the assumption that phosphorus is the main algal biomass limiting factor, and that the concentration of all forms of phosphorus present in the water body is a function of algal biomass. bukit merah reservoir (bmr) in malaysia is under threat from eutrophication due to increased intensity of agriculture in the upper catchments, agricultural development and an eco-tourism development surrounding the lake. recent work has highlighted the growing problem of siltation (ismail et al. 2010) and attention is now turning to nutrient fluxes. against this background, this paper, aims to quantify suspended sediment and nutrient loadings into bmr and assessing the trophic status of the lake. materials and methods study area the climate of bmr is an equatorial with an average daily temperature ranging from 23c to 33c. the mean annual rainfall recorded at bmr for the period 1953–2008 was 2905 mm (range 2200–3700 mm/year). the river inlets to bmr, are the merah (m) river, jelutong (j) river, selarong (s) river and kurau (k) river (fig. 1). the river discharge of merah, jelutong, selarong river are low with an average discharge of 1.03+0.59 m3/s, 1.04+0.47 m3/s and 0.11 +0.1 m3/s, respectively. major input to bmr lake is from kurau river with an average discharge of 27.2 m3/s ranging from 6.6-65.7m3/s. the capacity of the reservoir is 70  106 m3 at a water level depth of 8.5 m asl (ismail et al. 2010). based on the data the department of survey, malaysia, the land use of the bmr catchment area comprises oil palm (48.3 km2); rubber (98.9 km2); forest (196.9 km2); paddy (15.5 km2); and others (47.9 km2) (hidzrami, 2010). the land use changes in the catchment area covering the merah, jelutong and selarong subcatchments have also been described by amirin and hasmadi (2010). they found that from 1989 to 1999, forest cover decreased from 64% to 60% and 94% of bushes were mostly replaced by oil palm. the areal extension of oil palm plantations increased by 13% and of the paddies it increased by as much as 65%. field measurement and sample collection the sampling programme reported here covers a oneyear period from march 2008 to april 2009 on several monitoring sites of the bmr (fig. 1). the locations of the monitoring sites for the physico-chemical and biological variables of the river inputs and the reservoir outputs namely the kurau outlet and canals are represented on fig. 1. measurements of water quality and river flow were undertaken every fortnight at kurau river (k) and at the north pool outlet (onp). river flow were measured using current meter and discharge was calculated using a velocity-area method (shaw, 1994). discharge in the main inlets and the outlets was measured, and the water level was recorded continuously. in minor inlets and a few outlets, discharge was measured fortnightly and some time daily during rainy period. mean discharge was estimated by establishment of relationships between these instantaneous values and the calculated mean discharge from nearby hydrometric stations. the topmost water layer of bmr (at 0.5m depth) was analysed in situ for ph, dissolved oxygen (do) using a portable field ph meter (ysi portable meter), described by ismail and najib (2011) and ismail et al. (2010). water transparency was tested using secchi disk. water samples were collected every fortnight and analysed for suspended sediment concentration (ssc), total phosphorus (tp) concentrations and chlorophyll-a based on apha standard methods (apha 1989). ssc was determined by filtration using 0.45-μm whatman gfc filter papers and oven drying at 105c for 24 hours (apha, 1989). tp concentrations were determined with fig 1 bukit merah reservoir (bmr) and its catchment area located at north perak. the reservoir receives inputs from kurau (k), selarong (s), merah (m) and jelutong (j) rivers. six sampling stations in the lake are shown for s1 to s6. the water from the lake flows out of the system through the kurau outlet and 2 irrigation canals (selinsing and utama canal). yellow arrows show the input from the catchment, green arrow is the output from north pool and purple are output arrows from the south pool. suspended sediment, phosphorus budget and trophic status of bukit merah reservoir, perak, malaysia 3 the ascorbic acid method (apha, 1989), while chlorophyll-a was extracted with acetone for 48 h under dark and cold conditions (3–5 °c). the transmittance percentage of the extracts was read at 664-665 nm using a perkin elmer 25 uv–vis spectrophotometer following apha (1989). the estimation of sediment and nutrient loading is expected to be underestimated due to the sampling frequency, as during storms samples were not taken. trophic status index (tsi) this study used carlson’s trophic state index (tsi), also known as the carlson index, which was developed to compare secchi disk depth (sd), chlorophyll-a concentrations and tp concentrations (carlson, 1977), thus to classify regional surface waters, including streams and rivers. although chlorophyll-a is the most direct measure of algae biomass, carlson used secchi disc depth as the primary indicator since these three variables are highly correlated and are considered good estimators of algal biomass. the tsi was determined by the first three equations (eq. 1, 2 and 3) where tsi is in natural logarithm, and carlson tsi (eq. 4) is the average of the three tsi. tsi (sd) = 60-14.41 ln (sd) (eq. 1) where sd is mean secchi disc depth (m) tsi (chla) = 9.81 ln (chla) + 30.6 (eq. 2) where chla is mean chlorophyll-a (μg l-1) tsi (tp) = 14.42 ln (tp) + 4.15 (eq. 3) where tp is mean total phosphorus (μg l-1) carlson’s tsi = [tsi (sd)+tsi (chla)+tsi (tp)]/3 (eq. 4) the tsi range is related to productivity. a range between 40-50 is usually associated with mesotrophy (moderate productivity). index values greater than 50 are associated with eutrophy (high productivity), while values less than 40 refer to oligotrophy (low productivity). data analysis loadings of nutrients and suspended sediment in tonnes (t) between time interval k, were calculated by multiplying the discharge q (m3 s-1) by concentration s (mg l-1) over the time interval k (seconds) between samples based on the average sample load approach (littlewood, 1992). results sediment and phosphorus budget the simplified sediment and tp budget between the river inputs (kurau river and outlet from north pool) and the outputs (kurau outlet and selinsing and utama canals) is summarised in table 1. the south pool lake received sediment inputs from kurau river (k) and outlet from north pool (onp) totalling almost 15,800 t year-1 and about 19 t year-1of tp load. kurau river, which is the main river inlet to the bmr, contributed almost 82% of the total sediment input, amounting to about or 12,900 t year-1, while the tp load about was 11 t year-1 (60% of the total) during the study period. during the studied yearlong period water discharge, q (m3s-1) and suspended sediment loading of kurau river altered considerably (fig. 2). higher q and ss loads were observed from september to december 2008 (the north-east monsoon period), and april 2009 (early onset of inter-monsoon month). fig. 2 water discharge (q) in m3 s-1 and suspended sediment loads (t day-1) of kurau river during the study period 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 10 20 30 40 50 60 70 01.03.2008 17.09.2008 05.04.2009 s s l o a d ( t d a y -1 ) x 1 0 0 0 q ( m 3 s1 ) q ss load table 1 sediment and phosphorus budget for bukit merah reservoir (2008-2009) suspended sediment load (t) percentage (%) total phosphorus load (t) percentage (%) kurau river (k) ouput from north pool (onp) 12871.5 2899.6 81.6 18.4 11.32 7.45 60.3 39.7 total input 15771.2 100 18.77 100 output utama canal selinsing canal kurau outlet 4783.1 1461.4 3912.0 47.1 14.4 38.5 5.60 0.92 5.26 47.5 7.8 44.7 total output 10156.5 100 11.78 100 input–output 5614.6 35.6 6.99 37.2 4 najib et al. (2017) the total amount of suspended sediment flushed out from the lake system through the kurau outlet was about 3,900 t year-1 (38.5%), besides, nearly 4,800 t year1 (47%) was delivered through the utama canal and 1,500 t year-1 (14%) through the selinsing canal. thus, altogether the total sediment output from the reservoir was 10,157 t year-1. it was estimated that approximately 5615 t (36%) of the sediment delivered in 2008 to 2009 was trapped in the reservoir (see table 1). the total amount of tp flush out of the lake system through the kurau outlet was 5.3 t year-1 (45 % of the total outflux); while 5.6 t year-1 (47.5 % of the total outflux) were through the utama canal and only 0.92 t year-1 (8%) through the selinsing canal, amounting to a total tp output about 12 t year-1. hence, it can be estimated that approximately 37% of the tp was stored in the reservoir (see table 1). relationship between ssc and turbidity the relationship between ssc and turbidity at kurau river and outlet from north pool (onp) are shown on fig. 3 and 4. the relationship was good with r2 = 0.73 and r2 = 0.65, respectively. previous studies in 2007, including ismail et al. (2010) showed that the mean ssc in the lake was 8.61 mg l-1 ranging from 0.93 mg l-1 in the dry months to 38.0 mg l-1 in the rainy season (table 2). the mean ssc was higher in 2008 (13.5 ± 19.98 mg l-1). the mean turbidities in 2007 and 2008 were 12.4 and 23 ntu, respectively. the secchi disk depth, which is inversely related to ssc and turbidity, was higher in 2007 (mean = 0.85 m) than in 2008 (mean = 0.74 m) (see table 2). fig. 3 regression ssc and turbidity at sg. kurau fig. 4 regression between ssc and turbidity at outlet from the north pool tp and ssc relationship fig. 5 and 6 shows the relationship between tp contents of water and suspended sediment concentrations of samples collected at the sg kurau inlet and in the lake. the relationship is a strong positive log-linear function observed between logtp and logssc at kurau river (r2 = 0.69; fig. 5) and in the lake (r2=0.76, fig. 6). fig. 5 regression of log tp and log ssc at kurau river y = 0.56x0.98 r² = 0.73 0 5 10 15 20 25 30 35 40 45 0 20 40 60 s s c ( m g l -1 ) turbidity (ntu) y = 0.78x0.75 r² = 0.65 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 0 10 20 30 40 50 s s c ( m g l -1 ) turbidity (ftu) y = 1.39x 0.43 r² = 0.69 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.5 1.0 1.5 2.0 lo g t p ( u g l -1 ) log ssc (mg l-1) table 2 suspended sediment concentration (ssc), turbidity and secchi disk depth values of bmr in 2007 and 2008 2007 2008 parameter range mean ± stddev range mean ± stddev ssc (mgl-1) turbidity (ntu) secchi disk depth (m) 0.93–38.00 6.33–31.73 0.3–1.85 8.61±6.26 12.40±5.25 0.85 ± 0.25 0.13–202.0 5.88–64.10 0.26–1.20 13.52±19.98 22.92±15.95 0.74 ± 0.21 suspended sediment, phosphorus budget and trophic status of bukit merah reservoir, perak, malaysia 5 fig. 6 regression between log tp and log ssc in the lake trophic status table 3 shows the 3 tsi at 6 different sites of the lake. the average tsi (sd) was 64.12, which is indicative of an eutrophic status. the average sd transparency for the entire study period was 0.76m, with a minimum sd of sometime 0.3m after storms usually at the station near the kurau river mouth. during clear water sd could reach a maximum depth of 1.0m. this average sd is very shallow, less than 1 m showing less penetration of light cause by many factors ranging from maybe colloidal organic matter or colour (schindler, 1971), or turbidity from suspended inorganic particulates (zettler and carter, 1986) and phytoplankton (ostrofsky and rigler, 1987). table 3 trophic status based on three indicators for six sites in bukit merah reservoir sites tsi (sd) tsi (tp) tsi (chl-a) mean tsi s1 66.21 46.85 50.28 54.45 s2 68.49 43.84 55.40 55.91 s3 61.46 42.15 52.18 51.93 s4 61.27 43.88 53.98 53.04 s5 63.38 44.75 54.82 54.32 s6 63.94 45.73 61.38 57.02 mean tsi 64.12 44.53 54.67 54.44 class eutrophic mesotrophic eutrophic eutrophic notes: tsi is trophic status index; sd is secchi disc depth; tp is total phosphorus; chl-a is chlorophyll-a. the lake was classified as mesotrophic based on tp (tsi = 44.5); but slightly eutrophic based on chlorophylla (tsi = 54.5). the average classification was however slightly eutrophic with the value of 54.44, as it slightly exceeds the maximum limit for a mesotrophic classification (see table 3). discussion sediment fluxes the transport of suspended sediment derived from upstream sources affects the biogeochemical flux of downstream river systems (meybeck, 1984). into the studied reservoir most of the suspended sediment load came from kurau river, which drains a very dynamic catchment with vast differences in land uses, which in turn caus significant erosion and sediment transport in the kurau river catchment (see table 1). furthermore, due to its large size, the kurau river catchment produced much higher river discharge in the wet months when most of the sediment is transported from the catchment into the reservoir. large amount (36%) of sediment is deposited in the bmr annually (see table 1). the main contribution of sediment to the reservoir is from the kurau river, where about 82% (12,900 t year -1) of the total annual sediment input compared to the contribution from the north pool, which is about 18.4% (2,900 t year-1). the sediment yield of the kurau river is only about 39.8 t km-2 year-1, which is an underestimation because of the sampling frequency. however, it is comparable to other sediment yields in malaysia, which are affected by mixed land use dominated by agriculture (see table 4). large amount of sediment input to the bmr from kurau river is related to the recent land use change where about 46% of land uses consists of oil palm and rubber plantation. this cause high erosion and sediment transport, especially during rainy seasons. the rate sedimentation in the lake were reportedly to increase from a rate of 0.36 mm year -1 (1995–2000) to 0.48 mm year-1 (2000–2005) (ismail et al. 2010). such results go in line with other evidence illustrating that sediment delivery can be increased from 5 to 10 fold following major human impact (dearing and jones, 2003). the high sediment discharge of the kurau river also affecting the river and lake water turbidity and secchi disk depth transparency, especially at the river mouth (station s3, s4 in table 3). the increase in the sediment loading in aquatic systems in recent decades as demonstrated by the bmr (table 1) is an example of many cases of anthropogenic impacts on aquatic ecosystems globally. total phosphorus the primary sources of new nutrients to lakes are terrestrial runoff and atmospheric input. with the exception of some of the great lakes, internal reservoirs in lakes are relatively small, and lakes are therefore very responsive to seasonal inputs (guildford and hecky, 2000). the tp input for bmr was about 19,300 t year-1. this is probably related to the fact, that rubber, paddy and oil palm plantations cover 39% of the catchment area. y = 1.27x 0.29 r² = 0.76 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.0 0.5 1.0 1.5 2.0 lo g t p ( u g l -1 ) log ssc (mg l-1) 6 najib et al. (2017) the amount of tp retained in the lake was 36%, which is most likely absorbed to fine sediment. it suggests that large influxes of p into the lake may be held only temporarily in the reservoir, and subsequently it is released to growing plants and algae (harter, 1968). the high nutrient concentration recorded in bukit merah reservoir could be explained by the concurrence of various diffuse sources including intense agricultural (rubber, oil palm and paddy) throughout the basin accounted for almost 59% of tp flux into bmr (see table 1). usually lake sediments act as a sink for phosphorus (kaiserli et al., 2002). however, under certain conditions the sediment may become a phosphorus source that can support the trophic status of the lake system (ramm and scheps, 1997; zhou et al., 2001). not all of the phosphorus fractions, however, can be released from sediments into the overlying water and lead to lake eutrophication (gonsiorczyk et al. 1998). therefore, the phosphorus behaviour in lake sediments for promoting lake eutrophication can be more efficiently evaluated based on the examination of phosphorus geochemical distribution instead of the total phosphorus content (kaiserli et al., 2002). trophic status index (tsi) the lake was slightly mesotrophic based on tp but eutrophic based on chlorophyll-a and sd. naumann (1932) classified mesotrophic water as water with moderate nutrient concentrations and therefore it has more biological productivity and the water may be lightly clouded by organic matter sediment suspended solids or algae, while eutrophic water is extremely rich in nutrient concentrations with high biological productivity. the bmr lake water was also found to be slightly eutrophic, which is related to high productivity (see table 3). the high sediment load had a significant influence on the clarity or transparency of water in the lake, especially near the kurau river inlet and the inlet from north pool. secchi depth transparency is more strongly associated with the concentration of a particulate suspended matter than a dissolved organic matter (wetzel, 2001). thus, tsi (sd) is influenced by sediment from inlets and potentially by re-suspension of bottom sediment since the lake is shallow. the high sediment load causes significant influence on the clarity or transparency of water in the lake especially near the river inlet of sg. kurau river and inlet from north pool. chlorophyll has been significantly correlated with phytoplankton density (nicholls and hopkins, 1993). high chlorophyll concentrations are common in the bukit merah reservoir, eutrophication is related to high productivity and nutrient such as nitrogen and phosphorus, which are well-known essential nutrients for algal productivity. n and p can promote excessive algal growth. the combination of nutrient additions coming from streams and rivers, and the recirculation of nutrients from the bottom sediments can considerably cause more productivity than the waters of open lakes (stoermer, 1978). regarding the nutrient availability and recycling of phosphorus from the sediments, it has long been accepted that productivity in the reservoir is limited by phosphorus because of the extremely low concentrations present in the water column. it is also known that phosphorus is recycled into the aquatic system through sediment re-suspension events, dissolution and re-adsorption at the sediment and water interface (heath, 1995). this table 4 sediment yield of selected malaysian catchments catchment area (km2) sediment yield (t km-2 yr-1) source a. forested catchments bukit berembun, negri sembilan telom river, cameron highland mupor river, johor chuchuh river air terjun river (94% forest) 0.04 77 21.8 0.96 31.5 20 53 41 58-72 102 baharuddin (1988) shallow (1956) leigh and low (1973) rahaman and ismail (2006) ismail (2000) b. secondary forests tekam river sipitang, sabah 0.47 0.15 35 60 did (1986) malmer (1990) c. cleared or logged catchments tekam river, pahang sipitang, sabah ulu segama, sabah berembun 0.47 0.15 0.56 0.13 660 300 1600 189 did (1986) malmer (1990) douglas et al (1992) baharuddin (1988) d. urbanised catchments relau river, penang jinjang river, selangor kelang river, selangor 8.9 10.3 14.2 3100 1056 1480 ismail (1996) balamurugan (1991) balamurugan (1991) e. mixed land use pelarit river (quarry, forest) jarum river (urban, agriculture) kurau river (agriculture, forest) 49.5 94.5 323 151-310 92-156 40 rahaman and ismail (2006) rahaman and ismail (2006) this study suspended sediment, phosphorus budget and trophic status of bukit merah reservoir, perak, malaysia 7 is probably a factor of the heightened nutritional input that the bukit merah reservoir receives from point and non-point source pollution. conclusions in conclusion, both sediment and tp loading into bmr were reasonably high at about 15,800 t year-1 and 19 t year-1, respectively. these values were, however, underestimated due to the sampling programme that excluded storm samples. the main cause of reservoir sedimentation is the high sediment discharge from river inputs, especially from kurau river, which has the largest catchment upstream of bmr. the high nutrient concentration recorded in bmr could be explained by the concurrence of various diffuse sources, including intense agricultural activity throughout the basin, as well as, the increasing development in the drainage basins. most of the sediment is associated with erosion of the catchment areas affected by land clearing and agriculture, which cause the increase in the sediment and nutrients transported into the lake. in turn, this has caused a change in the water quality and the current state of the reservoir is slightly eutrophic with average tsi of 54.4. these data are critical in supporting future catchment management decisions for future improvement of the lake’s trophic status. acknowledgements the authors would like to thank professor william blake, university of plymouth, 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evaluation of phosphorus bioavailability in sediments of three contrasting lakes in china and the uk. chemosphere 42, 221–225. doi: 10.1016/s00456535(00)00129-6 zhu, g., qin, b., gao, g., zhang, l., luo, l., zhang, y. 2007. effects of hydrodynamics on phosphorus concentrations in water of lake taihu a large shallow eutrophic lake of china. hydrobiologia 581, 53–61. doi: 10.1007/s10750-006-0519-z introduction materials and methods study area field measurement and sample collection trophic status index (tsi) data analysis results sediment and phosphorus budget relationship between ssc and turbidity tp and ssc relationship trophic status discussion sediment fluxes total phosphorus trophic status index (tsi) conclusions acknowledgements references assessment of landscape conflicts in motorway planning, ne hungary journal of environmental geography journal of environmental geography 11 (1–2), 27–36. doi: 10.2478/jengeo-2018-0004 issn: 2060-467x assessment of landscape conflicts in motorway planning, ne hungary szilvia mészáros*, attila gergely, zsuzsanna illyés department of landscape protection and reclamation, szent istván university, villányi út 29-43, h-1118 budapest, hungary *corresponding author, email: szilvia.meszaros22@gmail.com research article, received 11 march 2018, accepted 25 april 2018 abstract field surveys are essential in the hungarian motorway planning process so that it would be possible to assess their impacts on the landscape, since the available databases are insufficient in respect of listing all the valuable elements of the landscape. the aims of the research are to analyse the impacts of the planned m30 motorway (located in north-eastern hungary) on the landscape, to enumerate the cultural and natural valuable elements of the landscape near and within the area to be expropriated, to explore the possibilities of their protection and to outline the possible land use conflicts likely to arise after the implementation of the motorway. the main sources used for the research were: landscape, green space management and environmental protection studies made for the modification of the affected settlements’ urban plans, field surveys alongside the entire track, and existing environmental databases. in the case of m30 motorway, the chosen corridor was mostly acceptable in the sections where the motorway track leads along the track of the existing main road 3, because it is fitted to an existing linear artificial landscape element, it is basically on the border of two natural microregions and can also fit into the existing land use structure. nevertheless, it is not considered to be the best choice in places where it separates vineyards from vine cellars, where it is located within 50 meters from residential areas or where it passes through small plot vineyards or horticultural areas instead of the arable lands of the nearby plain. keywords: european landscape convention, landscape protection, land use conflicts, planned motorway, ecological barriers introduction in accordance with the european landscape convention – ratified by hungary in 2007 – the landscape “is an area, as perceived by people, whose character is the result of the action and interaction of natural and/or human factors”. the preamble states that the landscape “contributes to the formation of local cultures and that it is a basic component of the european natural and cultural heritage”, it is “an important part of the quality of life for people everywhere” and “landscape is a key element of individual and social wellbeing and that its protection, management and planning entail rights and responsibilities for everyone”. thus, as a result of the above mentioned citations, landscape policy has to be integrated into any other policies – like transport planning – directly or indirectly impacting the landscape. road development has been a necessary task all through mankind’s history (rostovtzeff, 1926), but nowadays these road development demands have increased due to the rapid progress of motorization (jones, 2008). the establishment of transport connections and the provision of the existing connections’ usability are in the whole society’s interest, since road transportation has a lot of positive socio-economic effects as well, like increasing employment (by mobilizing manpower), aiding underdeveloped areas to catch up, strengthening urbanrural links (merriman, 2012). besides these aspects, road projects also have several negative environmental impacts on the landscape, which are highlighted in the research. nowadays technical limitations of road constructions have almost disappeared; roads can be led along completely new tracks almost everywhere in the landscape, without being adapted to the terrain or the hydrographic conditions. due to the rise of speed limit and increase of traffic, the geometry of the road must be adapted to strict technical standards in order to ensure road safety (gulyas, 2006; aarts and schagen, 2006) resulting in a greater intervention in the landscape: e.g. a 13 m wide two-lane road is less safe than a 16 m wide road (2+1 lanes) with a road separation cable barrier in the case of huge traffic load (bergh et al., 2016). moreover, in the case of a motorway the crown width is much wider (even 26.6 m as in the case of the m30 motorway) and road safety depends e.g. on the width of the emergency lanes or the central median barrier (bergh et al., 2016; bramaister, 1999) making the motorway wider. so the environmental impacts of road development can be more significant because of the greater intervention in the landscape than they were before the construction of motorways. a new road line and its connecting facilities (e.g. drainage ditch, petrol station, rainwater reservoir, new utility lines or just a temporary land use change which can be caused by the construction works) result in direct land use changes and land use structure changes; nevertheless, indirect land use changes often also occur as a result of better regional accessibility after the development of the transport links (eiter and potthoff, 2016; yuchu et al., 28 mészáros et al. (2018) 2016). in addition to the direct land use changes, the related land uses are limited by the buffer areas of the roads. (possible uses are regulated by gov. decree no. 253 of 1997 in hungary. it is forbidden to plan built-up areas except for industrial areas along the motorways in a 250 m wide area each side.) roads not only ensure good accessibility and connection between settlements, but can also be functional barriers for local people (hawbaker et al., 2006). furthermore, land use changes can result from the modified hydrological (or other abiotic) conditions which might be caused by the construction of road subgrade – e.g. disappearance of edaphic forest communities, like marshland forests (fi, 2000). besides, valuable land use can be endangered by road projects too, like historical land use structure (ihse, 1995), traditional land uses (antrop, 2005), unique landscape elements, characteristic plantings – like a line of trees with a special silhouette or a striking visual appearance, and a clump of trees, which can act as landmarks – alongside the road or forests (liu et al., 2014; gurrutxaga et al., 2011). the visibility of the roads and their connecting facilities mainly depends on the category of the road (need of earthworks), the relief, the vegetation and the surrounding buildings, but the perception of visual quality is an interaction between people and their environment (transportation research board of the national academies, 2013). visual impacts cannot be defined without interviewing the stakeholders (or without determining frequented viewpoints). visual changes occur due to the appearance of huge road embankments, bridges, noise walls; or the changes of the vegetation (e.g. disappearing of characteristic alleys). hungarian planning practice lacks methodology for quantifying or qualifying these visual impacts, but there are some good international examples to be adopted (the landscape institute with the institute of environmental management and assessment, 2002; transportation research board of the national academies, 2013). the landscape character assessment could also be a great basis for the road projects’ visual impact assessments (boromisza et al., 2011), as in scotland (kabai, 2010), where recommendations are offered based on the landscape character assessment concerning various types of interventions in the landscape (like a motorway or other roads) in order to minimize (or avoid) negative visual impacts. however, in hungary the realization of a landscape character based landscape classification system is currently in progress, and the recommendations are not yet known. there are also negative impacts on the ecosystem, among which the most important ones are fragmentation and habitat loss (forman and alexander, 1998; trombulak and frissel, 2000; bata and mezősi, 2013). fragmentation means that the roads are ecological barriers or filters for animal movement, subdivide populations and reduce the size of habitats. one of the results of fragmentation is animal mortality due to collision with vehicles, but the genetic consequences are more significant and dangerous (forman and alexander, 1998; trombulak and frissel, 2000). critical habitat reduction occurs when the habitat of insects falls below 1 ha, the habitat of small mammals falls below 10 ha or the habitat of birds falls below 100 ha (blake and karr, 1987; lord and norton, 1990). the landscape ecological research on the fragmentation of hungarian natural micro-regions made it clear that the most important ecological barriers are to be found in valleys, in small mountain pools, near lake balaton and near budapest (csorba, 2005). another negative ecological impact can be the rapid spread of invasive plant species in the disturbed surfaces – which endangers the naturalness of valuable habitats (hulme, 2009). moreover, negative ecological impacts can be caused by the disruption of local hydrological conditions, pollution of local watercourses by road run off, effects of road lightning or noise, effects of air pollution from vehicle emissions or disturbance during construction (byron et al., 2000). in spite of the numerous negative impacts, areas along the road track are habitats too, where protected species can subsist, e.g. orchids in the roadside or amphibians in drainage facilities (puky, 1999). in hungary, most of the road development projects are financed by the european union through the integrated transport development operational programme in the period between 2014 and 2020. altogether a huf 1,040 billion eu fund is allocated, approx. 30.5% of which serves for road development goals (integrated transport development operational programme, 2014-2020). one of the road projects to be financed by this operational programme is the planned m30 motorway between miskolc and tornyosnémeti, which is our study area. in accordance with annex 2 of gov. decision no. 1247 of 2016 this project is one of the national priority projects. the motorway is currently under construction and is planned to put into operation in 2021 (based on the website of the national infrastructure development corporation). the m30 motorway is part of the trans-european transport network (ten-t), namely „via carpathia”, between klaipeda–thessaloniki. the main aims of the research are to investigate the impacts of the planned m30 motorway on the landscape, to assess the possible impacts on the valuable cultural and natural elements of the landscape, to explore the possibilities of their protection and to outline the probable land use conflicts that might arise after the implementation of the motorway. land use conflicts can occur because the proposed developments and land use changes can affect landscape qualities that are valuable for people (bengston et al., 2004). land use conflicts are also the result of different perceptions of a group of people about landscapes and their services (brody et al., 2004). thus, a land use conflict is a contradiction between two neighbouring land uses – and the groups of people who use the land in different ways: which can cause functional (e.g. disturbance, functional barrier), ecological (e.g. disturbance of valuable habitats, pollution) and visual conflicts. study area the study area is located in borsod-abaúj-zemplén county, near the north-eastern border of hungary. the planned motorway is to lead towards slovakia’s second biggest city, kosice. the examined section is 56 km long and affects 21 settlements (fig. 1). the study area (see fig.1) also contains the plots connecting to the expropriation area of the assessment of landscape conflicts in motorway planning, ne hungary 29 motorway (the main reason for this is that exactly the same delineation was used in the corroborative examinations carried out for the modification of the affected settlements’ urban plans). fig. 1 location of the study area and the affected settlements the area studied in details is 3620 ha, of which the territorial distribution per settlement is shown in fig. 2 (with the length of the planned motorway). arnót and szikszó are the two most affected settlements in respect of the territorial distribution and the length of the motorway. the track of the motorway basically leads along the border of eastern-cserehát and hernád-valley natural micro-regions, and between arnót and szikszó the road track affects the sajó-hernád plain and the western-cserehát natural micro-regions (marosi and somogyi, 1990). the elevation is between 110 mbf (near miskolc) and 200 mbf (near tornyosnémeti, aszaló and szikszó) in the study area. the main soil types on the lower areas are various meadow soils (meadow, meadow chernozem, and meadow alluvial soil). the higher areas are covered by brown forest soils (ramann's brown forest soil, and chernozem brown forest soil). the climate is moderately warm and dry in the south and moderately cool and dry in the north, meaning that the average annual temperature falls between 9.2-9.6 oc and the annual rainfall is between 540-640 mm. the prevailing wind direction is northern, north-eastern. its average speed is 2-2.5 m/s. the determinative linear landscape elements in the examined regions are the watercourses (especially the hernád and kis-sajó rivers), the main road 3, and the railway line 90, which influenced the planning of the motorway’s corridor. in some places the chosen corridor leads along the flood bed of the river hernád, thus, the motorway’s embankment is also to act as the primary flood protection dike in some sections (e.g. between garadnahidasnémeti, garadna-forró, arnót-miskolc). the track of the planned motorway is almost parallel with the river hernád, which means it leads along the border of cserehát hills and the valley side of the hernád (fig. 3). the examined motorway is planned for a driving speed of 130 km/h, consequently the vertical and the horizontal technical parameters are appropriate for this speed. it is planned to lead partially along a whole new track, and to partially use the track of the existing main road 3, with 2+2 physically separated lanes and a 26.60 m wide crown. the crown of the crossing roads is 12.0 m fig. 2 affected area of settlements and the length of the motorway section 30 mészáros et al. (2018) and the parallel service roads are 7.00 m wide (the above mentioned technical parameters are summarized in the permitting plan: tura-terv ltd. et al., 2016). fig. 3 hydrological and topographical conditions of the study area methods the present analysis is a case study about the hungarian motorway planning practice. according to flyvbjerg (2006) single case studies can serve as a basis for drawing more general conclusions, provided that the case in question is sufficiently rich and illustrative. the m30 motorway was considered to be a particularly interesting case due to the diversity of the existing valuable cultural and natural landscape elements in this region, the nearness of the river hernád and the remaining traditional land uses. land uses are considered to be traditional, if the land use in question is extensive cultivation at a small-scale existing on the particular site for at least 100-150 years. as a primary source the findings of the landscape, green space management and environmental protection studies prepared for the modification of the affected settlements’ urban plans (department of landscape protection and reclamation, 2016) were used. all the affected settlements located between miskolc and tornyosnémeti were included in the analysis. the studies focus on current land use, valuable cultural and natural landscape elements of the affected area (which must adjust to plot borders because of the plan type), scenery, potential conflicts between the motorway and the surrounding land uses. proposals are also expected to be formulated for the future land uses (on the level of regulations within the frame of the urban plans). in these studies – made for the urban plan modification – other plans (environmental impact assessment, design plan) and historical maps (18-20th centuries military survey maps of hungary) were also considered. as a secondary source (besides maps and plans) field surveys were carried out alongside the entire track of the planned motorway. the expected land use conflicts were evaluated based on the field survey and the list of non-protected landscape elements is mainly based on this too (e.g. in the case of unique landscape elements national databases were not available for these settlements). as a tertiary source, the study area was analysed by using existing databases. for the preparation of maps shown in the research, the open street map database, the hungarian road network 2017 (provided by the hungarian public road non-profit plc), the protected areas (provided by the ministry of agriculture), the expropriation area of the planned m30 motorway (based on the design plan) and the srtm terrain model (interpolating 10 m contour lines) were used. for some figures the topographic map was used as a base map. the ‘las palmas’ version of quantum gis open source program was used. besides the summing up of the plans in connection with the planned motorway, some basic principles were determined based on the above-mentioned environmental impacts of the motorway implementation in connection with physical aspects related to valuable landscape elements and land uses. they are proposed to be considered in a road planning process so that the negative impacts on the landscape could be minimized. these are the followings: (1) ensure the continuation of traditional land uses (2) protection of valuable natural and cultural landscape elements (independently from the fact whether they are protected or not by law) (3) fitting to the current land uses so that the potential conflicts could be minimized between the motorway and the surrounding land uses assessment of landscape conflicts in motorway planning, ne hungary 31 (4) maintaining the ecological and functional connections in the landscape (minimization of fragmentation) (5) maintaining the valuable scenery relations and minimization of the negative visual impacts on the landscape. results and discussion the directly affected land uses located within the expropriation area – based on the field survey – are mainly arable lands, but orchards, acacia forests and oak forests, small plot vineyards and vine cellars, horticultural area with old walnut trees and wet pastures are also to be found. both the small plot vineyards and the horticultural areas are traditional land uses in the region: aszaló and szikszó are parts of the vine region of bükk. in the case of the section between miskolc and aszaló the planned motorway leads across the hilly vineyards and orchards, with a completely new track in the landscape and does not fit to any existing linear landscape elements or the topographical conditions (see the motorway section between szikszó and aszaló on fig.4 where those land uses are shown which are sensitive for the impacts of the planned motorway). an artificial, 100-250 m wide flood control channel of the river kis-sajó needs to be modified in arnót because of the chosen road corridor. fig. 4 the section between szikszó and aszaló doesn’t fit to the topographical conditions and the current land use structure there are natural values in the study area protected at international (natura 2000 areas) or national level (ex lege – that is protected by law – protected mottes, elements of the national ecological network) or at local level (local nature conservation area). furthermore, numerous valuable cultural and natural landscape elements are to be found here which are not protected by law, e.g. traditional land uses, unique landscape elements (see the definition below table 1). based on the overview map of the national, international natural values (fig. 5a) it can be stated that the chosen corridor is quite favourable, since it leads along the border of valuable landscape elements and land uses or it bypasses them. the affected valuable landscape elements per settlements are summarized in table 1, which contains not only the protected areas but also the other non-protected landscape elements. affectedness was considered as a real area demand, so these valuable elements are within the motorway’s expropriation area (they are endangered or would disappear during the construction of the motorway). over the total length of 56 km, passing through 21 settlements, the corridor affects one nature conservation area protected at local level (in szikszó, namely “magyar-hegyi macskaherés”), two natura 2000 areas (close to their border), 14 ecological corridors and 10 buffer areas of the national ecological network. the ecological corridors are mostly waterway crossings (10 out of 14). the planned motorway is also close to an ex lege protected motte (méra) and a spring (novajidrány), but they are outside the expropriation area. besides the mentioned natural values, a lot of non-protected valuable landscape elements are also endangered (see details in table 1), such as unique landscape elements, lines of trees, small plot vineyards, orchards, horticultural areas with old and characteristic walnut trees. a length of 9.6 km out of the 56 km (sections between hernádvécse-hidasnémeti and szikszó-arnót) of the planned motorway (see table 1) is within the priority area of scenery conservation (defined in hungary’s national spatial planning plan), due to the remaining traditional land use (e.g. near aszaló), the valley of the river hernád, and the traditional settlement structure (hernádszurdok). the track of the motorway leads along 7-8 km away from the zempléni protected landscape area between ináncs and tornyosnémeti, which is a valuable scenery relation between the protected area and the motorway (providing a “beautiful view” from the motorway). according to the field surveys there are some local valuable scenery elements – e.g. line of trees, shrubberies, waterways and wetlands alongside them, gallery forests – which would disappear as a result of the construction of the road (see fig. 6 and table 1). in the case of the m30 motorway the main expected land use conflicts per settlements are summarized in table 2. the most common conflicts which occur: potential pollution from rainwater drainage into living water (2), disturbance of residential areas and recreational facilities (3), and unfavourable changes in the local road transport because of the disappearance of an existing main road (6). in connection with the last mentioned conflict the main problem is that motorways are toll roads in hungary, while the use of the main roads is free of charge, so probably the traffic will flow back to the settlements. in the case of aszaló the motorway would be a significant functional barrier, because it separates the vineyards from the vine cellars, so these will be difficult to approach. 32 mészáros et al. (2018) table 1 affected landscape values per settlements settlement natura 2000 area spa/sci nature conservation area protected on the local level national ecological network unique landscape values and valuable scenery relations traditional land use/valuable landscape elements ecological corridor (pcs) buffer area (pcs) priority area for scenery conservation1 characteristic elements/ unique values2 miskolc 1 arnót 2 affected viewpoint vineyard with small plots szikszó “magyar-hegyi macskaherés” nature conservation area 2 affected viewpoint, line of trees traditionally cultivated hilly area: small plot vineyards, shrubberies onga viewpoint horticultural area with old walnut trees aszaló affected wine cellars, onetime farm of the landed gentry, line of trees traditionally cultivated hilly area: small plot vineyards and vine cellars, orchards halmaj horticultural area with old walnut trees, local ecological corridor kiskinizs local ecological corridor kázsmárk 1 roadside crucifix orchards, old poplar trees ináncs 1 csobád 1 line of trees local ecological corridor hernádszentandrás 1 not protected spring and wetland around it forró 2 onetime mill, roadside crucifix (3 pcs) encs sun-dial, 1956 memorial tree the gate of the settlement (with unique values) méra 2 3 line of trees (nearby an ex lege protected motte) vineyards and orchards szalaszend 1 line of trees novajidrány hubn10007 1 1 affected viewpoint, cemetery, funeral home, spring, onetime hunter mansion (nearby an ex lege protected spring) small plot vineyards and orchards garadna hubn10007/ huan20004 2 2 roadside crucifix, line of trees sports ground with old trees hernádvécse hubn10007/ huan20004 4 1 affected hernádszurdok hubn10007/ huan20004 1 1 affected traditional settlement structure hidasnémeti 4 affected roadside crucifix, line of trees old elm tree tornyosnémeti 1 line of trees 1 according to the national spatial planning plan of hungary. 2 unique landscape values are artificial or natural landscape values that have significance for the society from a natural, historical, cultural, scientific or aesthetic point of view (according to the hungarian nature conservational act). hubn10007: „zempléni-hegység a szerencsi-dombsággal és a hernád-völggyel” spa area huan20004: „hernád-völgy és sajóládi-erdő” sci area assessment of landscape conflicts in motorway planning, ne hungary 33 fig. 5 a) overview map of the national, international natural values (nature conservation by law); b) the section between forró and garadna doesn’t fit to the settlement structure and the new motorway causes many land use conflicts 34 mészáros et al. (2018) each mentioned conflict is a long-lasting and irreversible one (if a land use termination/changing is not considered as a “resolution” of the conflict). the main conflict in the case of the section between forró and garadna is the closeness of residential areas (on average within 250 m, in some cases within 50 m), which is shown in fig. 5b. the visual conflicts are considered to be significant when a minimum of 4 m high fill or 4 m deep cut is needed as an earthwork or there is a huge connecting facility (e.g. resting area, junction) and the residential areas are within 1 km off the planned motorway and there is no visual barrier (e.g. forest) (see conflict 7 in table 2). the possibilities of landscape protection related to motorway planning – considering both natural and cultural aspects – are basically determined by the corridor and the exact road track within the corridor. in this case – during the preparation of landscape studies made for the modification of the affected settlements’ urban plans – we proposed some track modifications in the phase of the design plan, because of the endangered valuable landscape elements (e.g. in order to protect lines of trees, unique landscape elements, and fitting into historical land use structure). but only one proposed modification was accepted in the case of novajirány, where the original track affected an ex lege protected spring’s source area (with old maple trees, willows). in the other cases (see the affected valuable landscape elements in table 1) most of the valuable elements will perish or if it is possible they will be relocated (e.g. roadside crucifixes). the affected valuable landscape elements are mostly of local significance (and not protected by law). compensatory measures are planned for the forests (it is regulated by law in hungary) and due to local demands (in the case of garadna, where a sports ground would be cut across by the motorway or in the case of novajidrány, where a funeral home would be destroyed). the mitigation measures for the possible land use conflicts can be plantations alongside the motorway or noise walls. in order to ensure the ecological connections, four ecological bypasses and five eco tunnels are planned along the 56 km long section (if the other waterway crossings are disregarded, which need to be built and also provide ecological connections: 10 of them are suitable for smaller mammals and two of them are suitable for big mammals). the number of the separate ecological bypasses is exactly the same as the number of the locations where the planned motorway cuts forests. it is important to note that the significant big mammal (boar, roe and red deer) migration corridors cover long sections according to the eia (tura-terv ltd. et al., 2016), and in the planning phase of the eia there were seven planned ecological bypasses for big mammals originally (four separate and three combined with a waterway). so all in all there are some facilities which are planned to ensure ecological fig. 6 some examples for the disappearing/endangered valuable landscape elements because of the motorway assessment of landscape conflicts in motorway planning, ne hungary 35 connections, but after the construction of the motorway migration of the wildlife will be much less possible than before. as much as the basic principles set out based on the potential impacts on the landscapes are concerned, it is not a black and white issue. since a motorway is a significant intervention in any landscape, it is impossible to construct a motorway without losses. the question is only the degree of the loss. in the case of the m30 motorway, the chosen corridor was mostly acceptable in the sections where the motorway track leads along the track of the existing main road 3, because it is fitted to an existing linear artificial landscape element, it is basically on the border of two natural micro-regions and can also fit into the existing land use structure. nevertheless, it is not considered to be the best choice in places where it separates vineyards from vine cellars, where it is located within 50 meters from residential areas or where it passes through small vineyards or gardens instead of the arable lands of the nearby plain. conclusions field surveys are indispensable in the hungarian motorway planning practice in order to list all the valuable cultural and natural landscape elements, since the available databases are insufficient for this purpose (e.g. unique landscape elements, local ecological corridors). after listing the valuable landscape elements, the determination of the valuable land uses and the analysis of the probable land use conflicts, the probable negative impacts of the motorway can be minimized by technical solutions (e.g. noise wall, ecological bypass), by plantations (alongside the road and also with future forests included in urban plans), or by relocating the unique landscape elements (e.g. roadside crucifixes). in the case of the m30 motorway compensatory measures are also planned (because of the forests and some local demands, that is a sports ground and a funeral home). the implementation of a motorway is always a national or at least regional interest of the society, however, the directly affected settlements and their habitants’ life does not necessarily become simpler in respect of land use (more difficult accessibility because of the disappearance of a lot of local transport connections), and the motorway also can also be a direct disturbance factor in the locals’ everyday life too. if an existing main road track is partially used to satisfy the planned motorway’s space demand, the local transport will necessarily flow back to the settlements and their main streets, which leads to growing traffic in residential areas. as for the unfavourable impacts made on the landscape, a motorway can obstruct the continuation of traditional land uses, it always changes the land use structure to a certain degree, and always is a functional and ecological barrier in the landscape. during the construction works several valuable cultural and natural landscape elements can be damaged or can perish, independently from the fact whether they are protected or not protected by law. the potential land use conflicts after the construction can arise directly between the motorway and the existing residential areas, the recreational facilities and also the cultivated lands, and finally it is also expected to lead to changes in land use in the long term. acknowledgements the authors would like to thank the hungarian public road non-profit plc and the ministry of agriculture for providing the basic map data for this research. table 2 probable main land use conflicts after the implementation of the motorway settlements m is k o lc a rn ó t s z ik sz ó o n g a a sz a ló h a lm a j k is k in iz s k á z sm á rk in á n c s c so b á d h e rn á d sz e n ta n d rá s f o rr ó e n c s m é ra s z a la sz e n d n o v a ji d rá n y g a ra d n a h e rn á d v é c se h e rn á d sz u rd o k h id a sn é m e ti t o rn y o sm é m e ti land use conflicts* 1 x 2 x x x x x x x x 3 x x x x x x x 4 x x 5 x 6 x x x x x x x x x 7 x x x x x x x x x x x x *1: wastewater treatment plant near the resting area (smell) *2: rainwater drainage into living water (potential pollution) *3: recreational facilities/residential area near (within 250 m) the motorway (disturbance, air pollution) *4: makes difficult to cultivate the vineyards, orchards (functional barrier to continue the traditional cultivating) *5: the location of ecological bypass is not compatible with the future land use (e.g. industrial area) *6: makes more difficult the local road transport (the current main road no. 3. can’t be used furthermore as a main road) *7: visual conflicts because of the motorway technical parameters (unfavourable visual element) 36 mészáros et al. 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(in hungarian) introduction study area methods results and discussion conclusions acknowledgements references application of gis for a climate change prepared disaster management in csongrád county, hungary journal of environmental geography 11 (3–4), 49–56. doi: 10.2478/jengeo-2018-0012 issn 2060-467x application of gis for a climate change prepared disaster management in csongrád county, hungary gergely kitka1*, anna kovács-győri2, jános tátrai1, viktor györgy oroszi3 1csongrád county directorate for disaster management, berlini krt. 16-18, h-6721 szeged, hungary 2university of salzburg, gis science doctoral college, schillerstraße 30, 5020 salzburg, austria 3budapest business school, faculty of commerce, catering and tourism, alkotmány u. 9., h-1054 budapest, hungary *corresponding author, e-mail: csongrad.titkarsag@katved.gov.hu research article, received 30 september 2018, accepted 1 november 2018 abstract the work of disaster management can only properly be supported by data stored in certified databases, since correct decisions can be made on the base of such data. nowadays these data can be found in databases managed by several organisations, or only a part of the necessary data is available through gis services. the tasks of disaster management include prevention, i.e. the preparation for potential incidents and the elaboration of related scenarios and plans taking into consideration the altering risk landscape caused by climate change. the development of modelling processes and applications based on gis databases and the integration of the results in work processes gain ground more and more in this work phase. geoinformatics is able to provide support for decision-making in two ways: in strategic planning and in the operative task solution. the present study demonstrates a multi-hazard multi-scale gis tool development in csongrád county (hungary) in accordance with the aims of the sendai framework. this geoinformatic tool is applicable to support the decision-making not only of the management board but the deployed rescue units in case of an evacuation through the optimized locations of the gathering places. keywords: database, modelling, evacuation, information acquisition, decision support, disaster management introduction natural hazards are causing significant lives and economic losses. the amount of losses expected to increase globally thanks to the climate change as it was concluded at the findings of the 5th ipcc assessment report and also showed by the results of natcatservice and sigma/swiss re global natural catastrophe loss databases of the past four decades. direct and indirect damages are rising mainly because of socio-demographic factors such as population growth, ongoing urbanization and increasing values (ipcc, 2014; hoeppe, 2016; newman et al., 2017; zuccaro and leone, 2018). new risks were generated, because the exposure of persons and assets has increased faster than vulnerability decreased, thus indicating the need to further strengthen disaster preparedness for response (unisdr, 2015). the number of natcatservice registered natural catastrophes were growing predominantly due to the weather-related events like storms and floods, but no relevant increase in geophysical events (e.g. earthquakes, tsunamis, and volcanic eruptions) was evident. this provides some justification to assume that climate change in particular, plays a relevant role in the ascending tendency of losses (hoeppe, 2016). the sendai framework was endorsed by the united nations general assembly in 2015. the framework solidifies a paradigm shift from managing disasters to managing current and future risks. it also foster resilience with an enhanced and leveraged disaster preparedness. one of the guiding principles indicate clearly that member states have the primary responsibility to prevent new and reduce existing disaster risk. furthermore it promotes collaboration across global and regional mechanisms (e.g. climate change adaptation and sustainable development) and institutions for the implementation and coherence of instruments and tools relevant to disaster risk reduction, sustainable development goals, especially goal 13 to “take urgent action to combat climate change and its impacts” including its specific target „to strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries” cannot be reached without taking into consideration the impacts of natural hazards in a changing climate (un ccs, 2017). clear connections were already established between the three global agendas including the paris agreement (fig. 1). synergies between climate change adaptation and disaster risk reduction are also emphasized in all the main strategies and agreements at eu and regional level e.g. eu climate change adaptation strategy, the eu cohesion policy and within the four eu macro-regional strategies including eu strategy for the danube region having a priority area (pa5 environmental risks) dedicated to both topics. beyond the eu civil protection mechanism several examples of effective transboundary collaboration exist to increase preparedness, for example, along the upper-rhine river the firefighting services in strasbourg and kehl train together and regularly exchange experiences. here countries are operating a joint river risk control training center to train specialists from both sides of the border. 50 kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. furthermore an illustrated french-german dictionary of emergency response vocabulary has been developed. above all the common deployment and joint cross-border management team of the ’europa 1’ firefighting vessel demonstrate the advantages of the enhanced preparedness on transboundary level (abad et al., 2018). for the better understanding of disaster risk, priority 1 of the sendai framework promotes access to and support for innovation and technology, together with the long-term, multi-hazard and solution-driven research and development in the field of disaster risk management. in addition, priority 4 urges to periodically review preparedness and contingency plans and strengthen technical and logistical capacities to ensure better response in emergencies. the framework also highlights the need towards regular exercises, including evacuation drills, training and the establishment of area-based support systems, with a view to ensure rapid and effective response to disasters and related displacement, including access to safe shelter, essential relief supplies, as appropriate to local needs (unisdr, 2015).the support services of prevention, preparation, planning, intervention and hazard defence – i.e. the most important activities related to disaster management – can be advanced considerably by means of a gis system. this fact has been recognised at national and local levels as well (lászló et al., 2014; sik et al., 2014; szatmári et al., 2014). providing relevant information to the public is an important part of prevention; during preparation, measures are to be taken to protect areas exposed to critical hazards; in the case of an incidental disaster, the organisation of rescue is the most important task; and plans are to be prepared for the period of temporary operation and for the restoration of the original state. in the phases of prevention, preparation and planning, gis solutions that can be used in practice should be provided for the persons who take part in the management of emergency situations. based on these solutions, the decision-makers will be able to make decisions on the rescue of human life and the protection of property, as well as on other priorities in disaster situations (mezey, 2007; perge, 2015). the tasks of disaster management can be executed in practice by the use of databases of adequate quality and the applications based on them. recognising this necessity, the csongrád county directorate for disaster management (csongrád cddm) started to plan gis tools, methods and applications, and to implement their practical use. the modelling principles developed by the csongrád cddm help the prevention work as well as the operative management when required. the application of the modelling processes is typical for a restricted circle of professionals, but their results can be used by the whole organisation via a web-based gis platform. the purpose of the development of this gis application is to manage the situations that may evolve during potential disasters and emergency situations, and to support the coordination of rescue and restoration. the new gis system/application can be used for the management of floods, industrial accidents and wideranging natural disasters that require prolonged defence. fig. 1 interlinkages among the global agendas (dazé et al., 2018) kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. 51 several studies and papers have been published in connection with emergency evacuation assisting decision support systems and modelling of vulnerability (cova and church, 1997; newman et al., 2017). in northern hungary, flash floods cause serious difficulties, and therefore the floodlog model was developed for this environment (ladányi and reko, 2014). the purpose of csongrád cddm was to develop and implement a gis system in which it would be possible to make projections and to retrieve data promptly in the case of sudden incidents (first of all information about the elements – population, objects etc. – exposed to hazards). study area the models and functions used in the presented gis system were developed specifically for csongrád county (flood areas, hydrography), in particular for the city of szeged. csongrád county is located in the southern border region of hungary, and szeged is the seat of the county. tisza, the second largest river of hungary, flows through the city, and has already put szeged to great hazard several times (1879, 1967 and 2006.). according to most recent official data, the population of szeged is around 161,000, and the administrative area of the city is 281 km2. due to its size, it is an ideal choice for the modelling of evacuation. it is a place with wide experience in floods, where the result of the modelling can play an important role in practice as well. any time soon, this evacuation model can be used for other similar places that may be exposed to the hazard of floods. data and methodology the lack of data and information available to actors is the another challenge associated with pursuing integrated approaches to adaptation, sustainable development and disaster risk reduction (un ccs, 2017). in the course of developing the gis database that serves as a basis for the presented gis system, it had to be taken into consideration that some of the data was maintained by other organisations and other data was based on own data collection.. one of the most important data sets consists of the results – derived data, for example: results of special analysis or query or select by location – of modelling and gis operations. csongrád cddm can use the databases of partner organisations either through an internet connection (public internet connection or virtual personal network – through a protected network connection) or with regular updating. most of these data consists of the data maintained by the general directorate of water management, and we have been able to use these data (e.g. information about flood areas in web map service). in the case of evacuation, the most important thing is to know how many people – and in how much time – can reach the designated assembly points from a given area after they have been properly alerted. investigations should also take into consideration the capacity and geometry of the transportation network, the current weather conditions and time of day (cova and church, 1997). the disaster related decision-making of individuals and societies is influenced furthermore by their attitudes during evacuation procedures. this was well illustrated in case of the xangsane typhoon event of vietnam where although the local population was well aware of the risks, the elderly did not want to leave their homes as it was unacceptable to die in another place (spiekermann et al., 2015). according to the experiences, this image can be modified considerably by the fact that some of the inhabitants will always move from the endangered area on their own. the ratio of these people can be different in the various city districts, depending on the social groups that live in the given location (the basic requirement of “self-evacuation” is having a motor vehicle). according to practical experiences the ratio of “self-evacuating” people is around 70%. evacuation compliance rates in hazardous material accidents, however, will likely be high, probably as high as 98% (sorensen and mileti, 1988). during the evacuation process, special attention must be paid to older people, people with impaired mobility and other people needing attendance, which can significantly influence the evacuation time (sorensen et al., 2002). making accurate plans are made difficult by the fact that the storage of such data may affect personal rights, though the knowledge of them is indispensable for accurate planning, since these people must be brought along separately – so their addresses and numbers are basic input data for route planning. now the disaster management authority is in possession of the residential addresses of people older than 70, and manages these data as a special output dataset indicated on the map as well. this result is presented in the web based gis platform (in a browser, recommended firefox, chrome). the geoprocessing results are presented automatically and could be download also in excel format. in the modelling phase, the worst case scenario should be applied, i.e. when all evacuees start to move on foot to the designated assembly point. so we have specially considered pedestrian traffic with a speed of 3 km/h (due to the movement of packages, children and family groups). several gis analyses were run for planning the evacuation at the level of the city. the concept was based on the assembly points defined in legal regulations. than three methods were used for gis analyses (1) generation of thiessen polygons (esri thiessen), (2) allocation (use the allocation analyst of the assembly points esri allocation) and (3) access time polygons (service area tool – esri service area) on the assumption of pedestrian traffic. in the thiessen polygon method, the result was not that much applicable, because the border of the result polygon can’t paste to system of the settlements. the allocation analyst showed better results but the result was not polygon, only it showed, that the addresses are which assembly point belong to. the final model was made in arcgis model builder for the planning of the scenarios (fig. 2). the reason for assuming pedestrian traffic was that in a crisis situation most people leave the danger zone without observing the traffic rules, and during the evacuation, usually the people who do not possess any motor vehicle to leave their home appear at the assembly points. 52 kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. the best result, i.e. the tightest (there is no empty area between the coverage) coverage of the area, was achieved by mapping of the access time polygons. the results of the evacuation model are used in the framework of stationary services in the gis system. the format of the data publication is web map service or web feature service. these two types could use on client (desktop gis software on a pc) or in a web gis application (in javascript environment or older version in flash). a special query function was developed (publicated in a geoprocess service on arcgis server) to give the accurate number of the people as required by the planning phase, and it makes it possible to collect the population data in an exact manner during the elaboration of the municipal emergency response plans. this facility will be integrated in the web-based system in the future (fig. 3.). in the case of evacuation an area based query was applied, since the affected area is maximum 0.25 – 1 km2 fig. 2 schematic diagram of the evacuation model fig. 3 the final gis application in use: flood area with population data of residential areas (farms). all municipal emergency response plans can be download. kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. 53 in this case (500 m distance from the source of danger), and this query is a complex operation, since the query is carried out on several separate databases at the same time. numerous zones can be set for the query of the information about the incident locations, depending of the type of the required data. with this tool, the head of the operation is able to designate the affected area and get immediate information about the population and other objects that can be found in the given area (fig. 4.). results the process of the use of the civil protection gis system can be divided into two phases. the phase of planning is performed mainly in desktop environment, with server support. some of the databases work in the desktop section as well, but special attention must be paid to their updating because the contact between the pc-s and the server is not constant. if somebody works without internet connect with an older version, the analysis could provide an inaccurate result, because the it department upgraded the database meanwhile. of course there is no problem in the web application. a server-based gis solution working in a protected internal network has been used for the support of operative work and other data retrieval processes. the application can be used at any location where the protected network can be accessed and does not require any special gis knowledge from the users. the division of labour within the system is as follows: close technical cooperation with the gis section in the planning and development phase (desktop and server administration); support of operative work from the web application exclusively for professional users. the system has been developed on the esri platform, in which arcmap 10.5 (desktop), arcgis for server 10.5. the databases types are geodatabases (special arcgis type) and mssql databases (mssql fig 4 the final gis application in use: manually appointed risk area with queried data, for example – population, population between 8 and 16 o’ clock. fig 5 the structure of final gis system with levels of operation, decision and maintenance 54 kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. server). we also use the databases in combination for the services. the data is stored in separated servers. the arcsde facility is used for data that can be edited in web environment (fig.5.) or in desktop environment. at the present, official evacuation districts are assigned based on the election districts defined by law (fig 6.). the applied model of the present study specifies new, gis based evacuation districts. the data of the evacuation modelling, the engineering structures of flood control (defence lines, floodgates etc.) and objects exposed to hazard can be accessed simultaneously in the geoinformatics system anywhere. fig. 6 the evacuation district of the city of szeged at the present defined by law (győri, 2015) the available functions integrated into the systems include data retrieval and other gis operations (query according to region or attribute, buffer zones, test of upper limit, distance measurement, coordinate query, export of gis data etc.) with the recently developed evacuation model, planning is not only possible with fixed input data (evacuation zones, assembly points) following the legal regulations rigidly, but a dynamic planning process can be developed as well. by changing the input parameters, it is possible to adapt to the changing circumstances, and it is not absolutely necessary to the data fixed in the municipal emergency response plans. if the situation requires the evacuation district may be changed by the spatial restructuring of the assembly points, which would be impossible in the case of a fixed plan. the model can be used to determine the areas that can be reached in intervals of 0-5, 5-15, 15-25 and 25-35 minutes. at the level of the locality, this series of intervals has ensured appropriate coverage for the existing assembly points. the districts generated as a result of modelling are not districts adjusted to streets. in the case of szeged, it can be seen that there is a “blind spot” even in the case of access time of 35 minutes. as for the blind spots, depending on the situation, the operative staff of disaster management may decide on the designation of new temporary assembly centres because of the 35-minute access time on foot (fig. 7.). in the case of evacuation zones established by modelling, the assembly points are loaded more or less uniformly. in the case of preventive planning, this spatial scheme is basically determined by the location of the objects that are essentially suitable for the role of an assembly centre. it has been one of the purposes of our modelling to analyse how the borders of the evacuation zones will change in comparison to those defined in the original legal regulations if we use the gis approach. however, if we compare the evacuation districts established by the two methods (i.e. the election districts and the gis analysis), considerable fig. 7 results of evacuation model with incident locations (győri, 2015) kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. 55 differences can be found in their spatial extent and location. due to strict legal requirements, the factors taken into account in the case of election districts are not the same as in the case of gis analysis. here only the population and other already existing geographical databases are needed for the modelling. several scenarios can been run for the final model. the variable parameter is the ratio of “self-evacuating” population. this parameter has been integrated into the model, thus the load of the individual assembly points can be calculated and the necessary further actions can be planned. the planning of the further measures related to the scenarios is continuous and depends on the actual situation. using this system, information layers that may help the management of incidents can be displayed anywhere in a web environment (fig. 8.). the results of queries and modelling can be exported to .kmz and .kml or .shp files, and these files can be used on-site with a suitable application on smart phones. the csongrád cddm favours the locus gis (www.locusmap.eu) application that has been able to operate offline on several field practices, since it is suitable for displaying the data, managing the gps and field data recording according to pre-defined templates (in .shp format). if required, the rescue unit which is exposed to a hazard can be followed on a public website by using the live tracking mode. the data can also be used without internet connection; furthermore, the application is suitable for recording data (e.g. the locations of drain water), which at a later moment, after recovery of the internet connection can be send to the server. conclusion in the field of disaster management, geoinformatics started to gain ground as a decision-supporting tool/system in the last 8-10 years. however, its areas of use are restricted to operative activity (support of immediate interventions). the presented approach intends to support the field of preparation and prevention as well in line with the requirements of the sendai framework. the modelling work was performed for a city of the size of a typical county seat in hungary. henceforth the csongrád cddm intends to use this model for every locality exposed to flood risk in the county and to store the available data in a database. the main problem was that the evacuation plans of residential areas were defined without gis planning. a new gis based approach was developed for the evacuation plans. the base of the gis application is the result of the model and the geoprocessing of the model. with this gis application the professionals can make established decisions between the variable circumstances. at the present the analysis was tested in szeged, but in the close future it will be applied to other settlements in csongrád county. the former practices and application experiences indicate clearly that this direction should be followed and may be used simultaneously with the evacuation districts defined by law. further planned steps include the adjustment of the modelling results to the geometry of the street network, but this requires further modelling work. geoinformatics as a strong tool of decisionpreparation and decision-support serves the preparation fig. 8 the geographical extent of the evacuation districts in the gis application in web browser. it can see the other relevant information layers which visible in the platform 56 kitka et al. 2018 / journal of environmental geography 11 (3–4), 49–56. for solving problems arising within the field of duties of civil protection. in the near future, the csongrád cddm is intent to continuously foster the usage of geoinformatic solutions. references abad, j., booth, l., marx, s., ettinger, s., gérard f. 2018. comparison of national strategies in france, germany and switzerland for drr and cross-border crisis management. procedia engineering 212, 879–886. doi: 10.1016/j.proeng.2018.01.113 cova, t.j., church, r.l. 1997. modelling community evacuation vulnerability using gis. int. j. geographical information science 11 (8), 763–784. doi: 10.1080/136588197242077 dazé, a., terton, a., maass, m. 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t.e. bilir, m. chatterjee, k.l. ebi, y.o. estrada, r.c. genova, b. girma, e.s. kissel, a.n. levy, s. maccracken, p.r. mastrandrea, and l.l.white (eds.). climate change 2014 impacts, adaptation, and vulnerability (contribution of working group ii to the fifth assessment report of the intergovernmental panel on climate change). cambridge university press, cambridge and new york, 1132 pp ladányi, r., reko, z. 2014. árvízi vészhelyzet logisztikai döntéstámogató eszköze arcgis alapokon (logistic decisionsupporting tool for flood emergency on arcgis bases). conference of esri users 9/11/2014, presentation in hungarian. lászló, p.; perge, k.; czikoráné balázs, e. 2014. a megújult katasztrófavédelmi térinformatikai rendszer (the renewed geoinformatics system of disaster management). in.: balázs b. (ed.) meeting of theory and practice in geoinformatics v, debreceni egyetemi kiadó, debrecen, pp. 199–204 locus gis (beta) version www.locusmap.eu mezey, gy. 2007. gis, modellezés és szimuláció a polgári veszélyhelyzeti tervezésben (gis, modelling and simulation in civil emergency planning). védelem online, national directorate general of disaster management, pp. 14 retrieved from: http://www.vedelem.hu/letoltes/anyagok/37-gis-modellezes-esszimulacio-a-polgari-veszelyhelyzeti-tervezesben.pdf) newman, j.p., maier, h.r., riddell, g.a., zecchin, a.c., daniell, j.e., schaefer, a.m., van delde, h., khazai, b., o'flaherty, m.j., newland, c.p. 2017. review of literature on decision support systems for natural hazard risk reduction: current status and future research directions. environmental modelling & software 96, 378–409. doi: 10.1016/j.envsoft.2017.06.042 perge, k. 2015. papírtérképektől az online térinformatikai alkalmazásokig (from paper maps to the online gis applications) védelem, katasztrófavédelmi szemle 22 (2), 5–8. sik, a., perge, k., lászló, p., czikoráné balázs, e. 2014. kockázati térképezés a seerisk projektben (risk mapping in the seerisk project). in: balázs b. (ed.) v meeting of theory and practice in geoinformatics v, debreceni egyetemi kiadó, debrecen, pp. 317-324 szatmári, j., kovács, f., van leeuwen, b., tobak, z., mezősi, g., mucsi, l., juhász, l., huszár, t., kitka, g. 2014. távérzékelés a katasztrófavédelem szolgálatában csongrád megyében (remote sensing supporting disaster management in csongrád county). in: márkus, b. (ed.) geoinformatics 2014. óbuda university, alba regia technical faculty, geoinformatics institution, székesfehérvár, pp. 375–388. sorensen, j.h., mileti, d.s. 1988. warning and evacuation: answering some basic questions. industrial crisis quarterly 2, 195–209. doi: 10.1177/108602668800200302 sorensen, j., shumpert, b., vogt, b. 2002. planning protective action decision-making: evacuate or shelter in-place? ornl/tm2002/144 report for the u.s. department of energy, oak ridge, pp. 1–23.to spiekermann, r., kienberger, s., norton, j., briones, f., weichselgartner, j., 2015. the disaster-knowledge matrix – reframing and evaluating the knowledge challenges in disaster risk reduction. international journal of disaster risk reduction 13, 96–108. doi: 10.1016/j.ijdrr.2015.05.002 unisdr 2015. sendai framework for disaster risk reduction 20152030. geneva, 37 pp. un ccs (united nations climate change secretariat), 2017. opportunities and options for integrating climate change adaptation with the sustainable development goals and the sendai framework for disaster risk reduction 2015–2030. technical paper, bonn, germany 27 pp. zuccaro, g., leone, m.f. 2018. building resilient cities: a simulationbased scenario assessment methodology for the integration of drr and cca in a multi-scale design perspective. procedia engineering 212, 871–878. doi: 10.1016/j.proeng.2018.01.112 legal regulations act cxxviii of 2011 on disaster management and on the modification of certain related laws, chapter i, section 3(25) act xxxvi of 2013 on the election procedure decree no 61/2012 (11 dec) of the ministry of the interior on the disaster management classification of localities and the modification of decree no 62/2011 (29 dec) bm of the ministry of the interior on certain rules of the defence against disasters government decree no 234/2011 (10 nov) on the execution of act cxxviii of 2011 on disaster management and on the modification of certain related laws (chapters v, vi and vii) introduction study area data and methodology results conclusion references journal of environmental geography journal of environmental geography 6 (3–4), 49–54. doi: 10.2478/jengeo-2013-0006 issn: 2060-467x comparison of pipette and laser diffraction methods in determining the granulometric content of fluvial sediment samples ágnes kun, orsolya katona * , györgy sipos, károly barta department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: k.orsi@geo.u-szeged.hu research article, received 25 august 2013, accepted 13 october 2013 abstract nowadays there is a growing demand for rapid and accurate determination of grain size distribution. the conventional pipette method is time-consuming and provides less detailed data compared to recently introduced methods. however, in hungarian practice the pipette method is still considered to be the standard one, as there are a long series of measurements, and grain size thresholds used in sedimentology and soil sciences are based on this approach. the aim of our research was to determine the comparability of the laser diffraction method (ldm) with the conventional pipette method (pm), in order to investigate the controversial question on the interchangeability of the two methods. based on our measurements on some representative fluvial sediment samples, we found that the largest difference in results can be expected in the silty grain size range. however if the main fractions (clay, silt, sand) are considered the methods provided similar very results, and correlation factors were above 0.92. in all, the ldm has a clear advantage because of its speed, reproducibility and fewer possibilities for operator failure. keywords: laser diffraction method, pipette method, fluvial sediments, grain size distribution introduction grain size distribution is a fundamental physical parameter in soil and sediment related researches. physical and chemical conditions of the sediment and soil samples are mostly determined by the main grain size fractions, which contain the majority of the particles. grain size classes are determined by almost each research field differently (blott and pye, 2012). grain size distribution can be determined in several ways, however in most research applications a fast and unified method is demanded, which offers reproducible and automated grain size measurements. in the past few decades, several researches have dealt with the methods of grain size distribution (konert and vandenberghe, 1997; buurman et al., 1997; beuselnick, 1998; goossens, 2008; di stefano et al., 2010; hernádi et al., 2008 stb.). a controversial question has been which method is the most proper for different applications. the aim of our research was to examine at what extent the conventional pipette method (pm) and the laser diffraction method (ldm) are interchangeable in terms of unsorted fluvial samples. the pm is internationally accepted for grain size distribution analysis, hence it was used as the basis during the comparison of the two methods. the pm is based on the stokes law, i.e. sedimentation rate is depending on particle size. there are however some conditions of its applicability: grains are presumed to be spherical and smooth, sedimentation rate must be constant, the density of particles equals to that of quartz (2.65g/cm 3 ), particle-to-particle interference and boundary effects from the walls of the sedimentation column are negligible and particles have no impact on the viscosity of the suspension (di gleira el al. 1957; konert and vandenberghe, 1997; di stefano et al., 2010). for example, if the first condition is not met the resulted clay content will be highly influenced by the shape of the particles. the settling velocity of the non-spherical grains in the fine fraction can lead to the underestimation or overe stimation of the clay content depending on the shape of the particle. platy shape grains lead to fine fraction overestimation while disc or rod shape grains result the underestimation in the range of 0.1 μm to 100 μm (di stefano et al., 2010). ldm is based on the dispersion and diffraction of a laser beam that is let through the suspension. the dispersion of light creates special diffraction rings on the sensor and the grain size distribution is determin ed by the position, size and distance between rings. the application of ldm has also got certain conditions (konert and vandenberghe, 1998), namely grains are spherical and particle orientation is random throughout the measurement time. however the flow of the measurement medium will likely to determine the orientation of non-spherical particles (de vos, 2001). 50 kun et al. (2013) the accuracy of the measurement also depends on the color of the suspension, the mineral composition of particles, the organic material and carbonate content of the sample and the applied measurement theory. in general two measurement approaches are applied for the ldm, the so called fraunhofer and mie theories. the fraunhofer theory is operating with the portion of light deflection that occurs as a result of diffraction. one major advantage of fraunhofer theory is lies on the fact that no knowledge of the optical properties of the examined material is required. however, the fraunhofer diffraction model provides inaccurate result if the size of the particles is less than 10  (wavelength of the laser light) (loizeau et al., 1994; xu and di guida, 2003; di stefano et al., 2010). for particles with diameters not significantly larger than the wavelength of the light used, the mie theory is applied usually for the analysis, in this case, however, the refraction index and the absorption index of the sample must be known. according to konert and vandenberghe (1997) the fraunhofer theory is well suited for non-spherical clay particles and the same conclusion was established by di stefano et al. (2010). measured grain size distribution is greatly a ffected by the applied pre-treatment method. the necessity of the removal of organic matter and carbonate content are strongly controversial. several authors justify the pre-treatment on sediment samples with high organic matter content (7-8%) (e.g. murray, 2002). according to his study, only pre-treatment with hydrochloric acid and hydrogen-peroxide could provide any degree of reproducibility. beuselnick et al. (1998) also investigated the effect of organic matter content, and found that the pretreatment with acids was unnecessary in case of samples with low organic matter content, and in spite of the different pretrea tment procedures the results had a strong correlation in the 3 main fractions (clay, silt, sand). a similar stat ement was made by ryzak and bieganowski (2011), namely physical (ultrasonic) dispersion can be equiv alent to chemical dispersion methods. materials and methods in order to determine the applicability of the ldm method, several authors have performed measur ements on soil samples, loessand marine sediments (konert and vandenberghe, 1998; di stefano et al. 2010; ryzak and bieganowski 2011; madarász et al., 2012). however unsorted fluvial samples are very rarely studied (buurman et al., 2001). consequently, the analysis was performed on sediments obtained from point bars and swales of a maros river paleochannel, near sannicolau mare, romania. samples were derived from 5 boreholes from depths of 30, 50, 70, 90 and 110 cm. in all 25 samples were analysed. samples were dried on 105 ˚c and sieved at a 2mm mesh size. the organic matter and carbonate content of sediments were also measured. carbonate content was under the measurement threshold (scheibler calcimeter) in case of 15 samples, while 10 samples had carbonate content between 0.42% and 3.35%. organic matter content was between 0.32% and 2.01 %. due to the low organic matter and carbonate content, and since the hungarian standard of the pm (msz-08 0206/1-78) does not contain orders of pre-treatment, we considered the removal of these components unnecessary in case of the investigated samples. the dispersion of the particles was enhanced using sodium pyrophosphate and shaking: 25 g of sample was weighted for the pm analysis, 0.5 g sodium pyrophosphate and 400 ml distilled water was added, then samples were placed in a shaking machine for 6 hours in order to disperse the aggregates into primary particles. after this pretreatment the suspensions were poured to 1000 ml sedimentation cylinders, which were then filled up with additional distilled water. based on the schedule of the khön’s table, 10 ml suspension was pipetted and put into a known -mass evaporating vessel, and the following grain size cl asses were determined <2 μm, 2-5 μm, 5-10 μm, 10-20 μm, 20-50 μm, >50 μm. for the ldm measurements a fritsch analysette 22 microtec instrument was applied. its measurement range is 0.08-2000 μm and it is equipped with 2 linearly polarized lasers: green (=532 nm, p=7 mw) and infra-red (=940 nm, p=9 mw). during the measurement, samples were homogenized with ultrasonic treatment (f=36 khz, p=60 w) for 3 min. the grain size distribution was determined at 108 channels. samples were measured sequentially for 3 times, during the measurement the ultrasonic dispersion was continuous. the difference of the distributions b etween the 3 measurements was at maximum 3 -4% (fig. 1), hence the third measurement was considered as the primary grain size distribution. in order to compare the results of the two methods, intervals of the pipette method were generated out of the contin uous distribution curve yielded by the ldm measur ements. grain size distribution analysis was performed by statgraphics software. fig. 1 differences between three consecutive ldm measurements on the same sample comparison of pipette and laser diffraction methods in determining the granulometric content of fluvial sediment samples 51 results the texture of the samples was different, but similar attributes characterized the samples along the bor eholes (regardless of depth). the highest clay content was measured in borehole sn5, where nearly identical sand content was measured with the two methods. in the meantime borehole sn11 showed the lowest clay content, while these samples had the highest sand contents. beyond texture analysis, median diameter (d50) and cumulative distribution with 10, 25, 75, 90% values (d10, d25, d75, d90) were also measured. differences and ratio of the resulted values d erived by the two methods were used for the comparative analysis (fig. 2). samples of borehole sn11 – with the lowest clay and highest sand contents – showed the greatest differences of cumulative distribution values (d25, d50, d75, d90) obtained by the ldm and the pm. the sources of the dissimilarity have been searched in the differences of sand contents. during the pm, removal of sand content was performed after sedimentation; therefore presence of sand grains could have disturbed the sedimentation speed of grains of other fractions. moreover, borehole sn12 contained a large amount of sand, d75 and d90 values were also high. differences between d values were the lowest in the samples of boreholes sn3, sn4 and sn5. these samples have the lowest sand content, and amount of sand grains was roughly the same after the measur ements of the two methods. based on the d values, samples can be divided into two groups: sn3, sn4, sn5 and sn11, sn12. classification is also confirmed by the spatial distr ibution of the samples, as the samples of the first group is originated from the point bars and swales of the aranka river, while sn11 and sn12 were obtained from a 6.1±1.1 ka old, meandering riverbed (kiss et al., 2012). measured organic matter content also r eflects this difference of sample groups. the first group (sn3, sn4, sn5) has an average organic matter co ntent of 2.1%, while the second has an average of only 0.8%. dissimilarities of samples in grain size distrib ution and organic matter reflects to the river dynamics of the formerly accumulating river. the samples of the first group belong to the clayey and organic matter rich landforms of a meander with a low discharge, while samples of the second group reflects to a co nsiderably large meandering river (kiss et al. , 2012). since cumulative and differential size distributions of the samples were similar in each group, distributions will be represented by one sample per group. comparison of the two methods can be performed by examining the distribution curves. in the case of sample sn3, the shape of distribution curves derived by the two methods are very similar (fig. 3). results of the ldm were evaluated using the defined fraction intervals of the hungarian standard. curves are bimodal and their main modus is equivalent, however the secondary modus of the ldm curve is displacing towards the coarser fractions. the peak of the ldm curve is at a larger particle size compared to the pm curve. the differences between the measurements have occurred at different fractions that depend on the proportion of the fractions. the samples sn5 with high clay content shows significant difference in clay proportion, regardless that difference between d values are the lowest in this borehole (fig. 4). the largest difference can be identified in clay contents, co nfirmed by former statements as the increase of clay content is also increasing the error and probability of underestimations during ldm (beuselick et al., 1998; konert and vandenberghe, 1998). in case of high clay content the ldm underestimates the clay fraction in favor of the silt fraction. however the pm overestimates the fine fractio n because of the non-spherical shape of the clay particles. underestimation of clay content with ldm was also fig. 2 difference between the d values derived by pm and ldm 52 kun et al. (2013) typical in other samples of the group. differences between the ldm and pm are also visible on sn11 and sn12 samples (fig. 5), where the ldm measured lower sand content that can be related to the metho dology of sedimentation processes formerly described. errors during sand content calculations can be e xplained with the rough surface of grains that leads to the underestimation of sand and therefore overestimation of silt. analyzing the results of samples the distribution curves can be very different in certain cases, hence we analysed the result with another approach as well. for every sample we determined the amount of particles in the main fractions (clay, silt, sand) with the two methods, and then we examined the correlation between them. taking the sediment categories into account, a high correlation was found between the ldm and pm sand, silt and clay content. fig. 3 pm and ldm grain size distribution and cumulative curves of sample sn3/70 fig. 4 pm and ldm grain size distribution and cumulative curves of sample sn5/110 fig. 5 pm and ldm grain size distribution and cumulative curves of sample sn12/90 comparison of pipette and laser diffraction methods in determining the granulometric content of fluvial sediment samples 53 table 1 shows the linear function that is calc ulated by the amount of particles in the main fra ctions. figure 6, 7, 8 shows how the values fit on the linear function per each main interval. there is no case where the values are outside of the confidence interval (95%). the correlation factor is significantly high concerning all main fractions, despite the difference between the dispersion curves based on the two methods. for exploring this difference, we e xamined the correlation as well in each interval ( table 2). the lowest correlation factors were experienced in case of coarse silt (10-20 μm) and the fine sand (20-50 μm) fractions. based on linear regression, separation of the particles with 10 -50 μm diameter is problematic. several author found the results of this fraction doubtful, hence they expressed the silt fra ction mathematically as a function of the known clay and silt fraction (beuselnick, 1998; buurman et al., 2001; ferro and mirabile, 2009; di stefano et al., 2010). the modification of the silt fraction’s limit is suggested by konert and vandenberghe (1997) in order to correct the underestimated clay fraction. fig. 6 correlation between clay content determined by the two methods fig. 7 correlation between silt content determined by the two methods fig. 8 correlation between sand content determined by the two methods conclusion in our research we examined the interchangeability of two different grain size measurement methods in case of unsorted fluvial samples. during the invest igation we compared the cumulative and distribution table 1 correlation of the main fractions determined by different methods size class ( μm) texture correlation factor linear regression <2 clay 0.928 y=0.179x+6.764 2-5 silt 0.934 y=1.036x+16.841 5-10 10-20 >20 sand 0.951 y=0.482x+28.663 table 2 correlation between results received for different grain size classes size class (μm) correlation factor linear regression <2 0.929 y=0.180x+6.,667 2-5 0.921 y=1.014x+8.992 5-10 0.899 y=0.974x+8.336 10-20 0.676 y=0.566x+15.124 20-50 0.567 y=0.447x+16.871 >50 0.951 y=0.483x-3.551 54 kun et al. (2013) curves produced by the two methods, studied the effect of clay, silt and sand abundance on distrib ution difference, and determined the correlation b etween results received for the main fractions (clay, silt, sand). in case of high clay content, the ldm seems to underestimate the clay content in favor of the silt fraction. in the meantime the pm seems to overest imate clay and therefore the proportion of the silt fraction is significantly lower. the pm systematica lly overestimates the sand fraction compared to the ldm results. the ldm underestimates the sand fraction for the benefit of silt fraction because of the rough surface of the sand particles. the interchangeability of the two methods in terms of the silt fraction is doubtful if distribution curves are considered. however, if the bulk values are calculated for the main fractions, differences are not significant. the lowest correlation factors we re found in case of coarse silt (10-20 μm) and fine sand (20-50 μm). therefore, the comparative analysis of particles with a 10-50 μm diameter is problematic. acknowledgement the research was supported by the huro/0901/266/2.2.2 project. references beuselinck, l., govers, g., poesen, j., degraer, g., froyen, l. 1998. grain-size analysis by lase diffractiometry: comparison with the sieve-pipette method. catena 32, 193–208. blott, s.j., pye, k. 2012. particle size scales and classification of sediment types based on particle size distributions: review and recommended procedures. sedimentology 59, 2071–2096. bork, h.r. 1989. soil erosion during the past millennium in central europe and its significance within the geomorphodynamics of the holocene. catena supplement 15, 121–131. buurman, p., pape, th., reijneveld, j.a., de jong, f., van gelder, e. 2001. laser-diffraction and pipette-method grain sizing of dutch sediments: correlations for fine fractions of marine, fluvial and loess samples. netherlands journal of geosciences 80 (2), 49–57. de vos, b.v. 2001. relationship between soil textural fractions determined by sieve-pipette method and laser diffratiometry. wetenschappelijke instelling van de vlaamse gemeenschap, instituut voor bosbouw en wildbeheer di stefano, c., ferro, v., mirabile, s. 2010. comparison between grain size analyses using laser diffraction and sedimentation methods. biosystems engineering 106, 205–215. ferro, v., mirabile, s. 2009. comparing particle size disturbation analysis by sedimentation and laser diffraction method. journal of agricultural engineering 2, 35–43. fritsch 2009. particle sizing laser diffraction, http://www.benelux-scientific.be/ fileadmin/user_files/pdf/poederkarakterisatie/laserd/las er_diffraction.pdf, available 2012–08-31 goossens, d. 2008. techniques to measure grain-size distributions of loamy sediments: comparative study of ten instruments for wet analysis. sedimentology 55, 65–96. hernadi, h., makó, a., kucsera, s., szabóné kele, g., sisák, i. 2008. a talaj mechanikai összetételének meghatározása különböző módszerekkel (determination of soil mechanical composition by different methods). talajvédelmi különszám konert, m., vandenberghe, j. 1997. comparation of laser grain size analysis with pipette and sieve analysis: a solution for underestimation of the clay fraction. sedimentology 44, 523–535. loizeau, j.l., arbouille, d., santiago, s., vernet j.p. 1994. evaluation of wide range laser diffraction grain size analyser for use with sediments. sedimentology 41, 353– 361. madarász, b., jakab, g., szalai, z., juhos, k. 2012. lézeres szemcseösszetétel elemzés néhány előkészítő eljárásának vizsgálata nagy szervesanyag-tartalmú talajokon (examination of sample preparation methods for the laser grain size analysis of soils with high organic matter content). agrokémia és talajtan 61 (2), 381–398. mccave, i.n., bryant, r.j., cool, h.f., coughanowr, c.a. 1986. evaluation of laser-diffraction-size analyser for use with natural sediments. journal of sedimentary petrology 56, 561–564. murray, m.r. 2002. is laser particle size determination possible for carbonate-rich lake sediments? j. paleolimnol. 27, 173–183. ryzak, m., bieganowski, a. 2011. methodological aspects of determining soil particle-size distribution using the laser diffraction method. journal of plant nutrition and soil science 17, 624–633. xu, r., di guida, o.a. 2003. comparison of sizing small particles using different technologies. powder. technology 132, 145–153. http://www.akademiai.com/content/d0115575u5155h70/ http://www.akademiai.com/content/d0115575u5155h70/ http://www.akademiai.com/content/d0115575u5155h70/ journal of environmental geography journal of environmental geography 6 (1–2), 21–27. doi: 10.2478/v10326-012-0003-3 issn: 2060-467x modeling the impacts of climate change on phytogeographical units. a case study of the moesz line ákos bede-fazekas department of garden and open space design, faculty of landscape architecture, corvinus university of budapest, villányi út 29-43, h-1118 budapest, hungary e-mail: bfakos@gmail.com research article, received 29 january 2013, published online 15 april 2013 abstract regional climate models (rcms) provide reliable climatic predictions for the next 90 years with high horizontal and temporal resolution. in the 21st century northward latitudinal and upward altitudinal shift of the distribution of plant species and phytogeographical units is expected. it is discussed how the modeling of phytogeographical unit can be reduced to modeling plant distributions. predicted shift of the moesz line is studied as case study (with three different modeling approaches) using 36 parameters of remo regional climate dataset, arcgis geographic information software, and periods of 1961-1990 (reference period), 2011-2040, and 2041-2070. the disadvantages of this relatively simple climate envelope modeling (cem) approach are then discussed and several ways of model improvement are suggested. some statistical and artificial intelligence (ai) methods (logistic regression, cluster analysis and other clustering methods, decision tree, evolutionary algorithm, artificial neural network) are able to provide development of the model. among them artificial neural networks (ann) seems to be the most suitable algorithm for this purpose, which provides a black box method for distribution modeling. keywords: climate change, remo, climate envelope model, phytogeography, moesz line, model improvement introduction the latest regional climate models (rcms) have high horizontal resolution and good reliability. they provide projections for the carpathian basin that are related to botany (czúcz, 2010), landscape architecture (bedefazekas, 2012a), and forestry (mátyás et al., 2010; führer et al., 2010; czúcz et al., 2011). our future climate, which is likely to be warmer, dryer in summer, and have more extreme precipitations in the colder half-year term (bartholy et al., 2007; bartholy and pongrácz, 2008), will enforce changes in the composition of the natural and the planted vegetation. the landscape architecture can have a significant role on the mitigation. we should note, however, the importance of adaptation, since climate change cannot be compensated by the intensive garden maintenance (bede-fazekas, 2011). one of the most important tools from the adaptation toolkit of landscapes architecture is the reconsideration of the ornamental plant assortment. there are some papers dealing with this issue (schmidt, 2006; szabó and bede-fazekas, 2012). geographical visualization can be produced with gis (geographic information system) software based on the large amount of tabulated data of the different climate models, which might be interpretable not only by experts. they are able to visualize the direction and the volume of climate change also for non-professionals (czinkócky and bede-fazekas, 2012). this is true in case of different modeling themes, such as the distribution area of the mediterranean plant species; the distribution area of the plant species migrating northwards from the carpathian basin; and the phytogeographical units and borders that may shift from or shift to the carpathian basin. phytogeography, a branch of biogeography, is concerned with the distribution area of plant species, communities and floras. this paper summarizes the experiences gained by the model run on the moesz line as a case study and highlights the possible improvements of the model, including the application of artificial intelligence (ai) algorithms. there are really few models that have studied the assortment of plants able to spread through or be introduced in the carpathian basin in the 21 st century. there are, however, numerous researches that have connection with these modeling approaches. the research of horváth (2008a) about finding the territories having similar climate nowadays to the future climate of hungary has high importance. he has found that these 22 bede-fazekas (2013) spatially analogue territories are, for the next 60 years, the following: south rumania, north bulgaria, serbia, and north greece (horváth, 2008b). by studying the vegetation and ornamental plant assortment of the analogue territories we can estimate the future vegetation and the possibilities of ornamental plant usage in the future in hungary. among forestry species the distribution of beech (fagus sylvatica l.) has been modeled (führer, 2008). the impacts of climate change on the natural vegetation and habitats were studied by kovács-láng et al. (2008) and czúcz (2010). artificial neural network, is one of the artificial intelligence methods described further as a recommended improvement of the model, was used for modeling the inland excess water by van leeuwen and tobak (2008). apart from hungary, there can several researches be found using similar methods to that ones i suggest in the discussion. one of the most significant is the work of arundel (2005), which is about find ing the climate envelope of five warm-demanding species of north america by significance analysis. modeling was, however, not carried out by him. berry et al. (2002) modeled the distribution of 54 species and the composition of 15 habitats of ireland and great britain. harrison et al. (2010) studied the potential composition change of the vegetation of oregon. the distribution of 134 north american tree species was modeled by iverson et al. (2008) with the use of regression trees. stankowski and parker (2010) found that regardless of distributional and environmental data, there is not any algorithm which could maximize model performance for all species; thus different sp ecies demand different models. guisan and zimme rmann (2000) give full review of the metho ds that can be used for ecological modeling. methods of modeling the approach of modeling the shift of phytogeographical units can be reduced to modeling the potential distribution area of fictive or real species bound to the phytogeographical unit. the inputs of the model are the current distribution of the plant species, the climate date for the reference period, and the climate data for the future period(s). there are three main steps: 1) querying the climate demands/tolerance of the species; 2) validating the model (modeling the reference period); 3) predicting (modeling for the future period). the climate requirements of the species can be filtered based on the distribution and the climate data of the reference period, since the extremes of a certain climate parameter indicate the tolerance boundaries of the species. the selection of climate parameters, however, is subjective. note that the model can fail if not enough or too much fig. 1 observed distribution, modeled potential distribution for the reference period, and predicted potential distribution for the future periods of cork oak (quercus suber) modeling the impacts of climate change on phytogeographical units. a case study of the moesz line 23 climate parameters are selected (bede-fazekas, 2012a). the result of this phase is a list of climatic limits (a zeroorder logical formula in mathematical terms) per species, therefore the climate requirements of the species are written as equations. this is the mathematical basis of the prediction that used in the next phase. based on the knowledge of the climate requirements, the territories providing suitable climatic environment for the plant can be filtered according to the climate data of the reference period. the sum of these territories is the potential distribution area. modeling the potential distribution for the reference period is seemingly unnecessary and negligible, and it does not influence the result. this medial phase of modeling is, however, not to be omitted, since the result of this phase provides for the possibility of validating. the reliability of the future predictions (model results) can be concluded by comparing the observed distribution to the modeled potential distribution. in case of much greater area of distribution the model results are not to be reckoned as reliable results, irrespective from the known influence of anthropogenic, edaphic and competitive effects on the real distribution. therefore, the similarity of the observed and modeled distribution can guarantee that the model is reliable enough. based on the climate demands of a certain plant species and the climate data, the suitable territories can be filtered not just for the reference period but also for the future periods. this third phase is the modeling/prediction approach in the strictest sense; this is about finding the future potential distribution (fig. 1). the method of modeling the future shift of moesz line (also called as grape line) is going to be reviewed, which is appropriate example of modeling a phytogeographical unit based on modeling the distribution of separate species. moesz (1911) observed that the northern borders of 12 plant species are highly correlated with each other, and this line is also the northern border of the vine cultivation area. this phytogeographical line, which is situated near the southern foot of the western carpathians, was later named after moesz. there is hardly any international literature about the moesz line, since it is of local importance. note, that elongation of the grape line to the west and to the east results in an extended phytogeographical line which still correlate with the northern border of some species originally bound to the moesz line (eg. muscari botryoides – somlyay, 2003). the extended line characterizes not only the flora and ornamental plant assortment of the carpathian basin, therefore modeling the moesz line can have importance for entire continent. there are several approaches of modeling a phytogeographical line. three different methods (called line modeling, distribution modeling, and isotherm modeling) are going to be discussed. the models were run by the spatial analyst module of the gis software esri arcgis. all of them were based on the regional climate model remo, which has a grid resolution of 25 km. although the entire european continent is within the domain of remo, we used only a part (25724 of the 32300 points; fig. 2) of the grid. the reference period was 1961-1990, while the future predictions were applied for the periods 2011–2040 and 2041–2070 based on the ipcc spes scenario called a1b. isotherm modeling among the three methods is the easiest to apply. it is based on finding that winter minimum temperature isotherm that correlates with the phytogeographical line most of all. the predicted shift of the isotherm probably indicates the shift of the fig. 2 the domain of regional climate model remo (grid) and its part used in the study (within the rectangle) 24 bede-fazekas (2013) phytogeographical line. the main disadvantage of this method is that the existence of this isotherm cannot be guaranteed in case of all phytogeographical borders (in case of the moesz line the appropriate isotherm was found). only one or a few climatic parameters are considered by this method, thus it is a rather inaccurate and not so reliable method. moreover it can yield to a result that is hard to interpret (similar to the case of isotherm modeling of moesz line). nevertheless, it is a very fast method and does not require digitizing distribution areas. line modeling is a somewhat complicated method. it is based on modeling the shift of the distribution area of a fictive species, whose northern distribution borders coincide with the phytogeographical line (the southern border is irrelevant). it is a slow but somewhat more accurate method. the most complicated method is called distribution modeling, which is also the slowest one. the model is run on the distribution of numerous plant species bound to the phytogeographical line separately. then the northern borders of the predicted potential distributions are merged. the method provides detailed result, but drawing the final line (the prediction) is still subjective. detailed comparison of the three aforementioned modeling methods is published by bede-fazekas (2012b). distribution modeling is, in methodical terms, similar to multiple line modeling. line modeling is a kind of climate envelope modeling (cem) which is about predicting responses of species to climate change by drawing an envelope around the domain of climatic variables where the given species has been recently found and then identifying areas predicted to fall within that domain in the future (ibáñez et al., 2006, hijmans and graham, 2006). it assumes that (present and future) distributions are dependent basically on the climatic variables (czúcz, 2010) which is somewhat dubious (skov and svenning, 2004). 36 climatic variables were used for the modeling: monthly mean temperature (°c), monthly minimum temperature (°c), and monthly summarized precipitation (mm). all the climatic data were averaged in the periods of thirty years. results of line modeling the results of line modeling is shown in fig. 3. the method was visually validated (by the correlation of the moesz line and the modeled line for the reference period). some measurements are also known for model evaluating, eg. cohen’s kappa (cohen, 1960) and roc/auc (hanley and mcneil, 1982), they are, however, based on measuring areas instead of coincidence of curves. the observed precision is good enough despite of the relatively low horizontal resolution of the climate data. the modeled distribution of the fig. 3 observed distribution, modeled potential distribution for the reference period, and predicted potential distribution for the future periods of the fictive plant species bound to the moesz line in case of the line modeling method modeling the impacts of climate change on phytogeographical units. a case study of the moesz line 25 fictive species shows a northern border from southern france, through the southern and eastern foot of the alps, the southern foot of western carpathians, the western foot of the eastern carpathians, the southern and eastern foot of the southern carpathians, to southern ukraine. the prediction for the period 2011–2040 shows not such a great shift in the carpathians as it was expected. remarkable shift can be seen in france and to the east of the eastern carpathians. for the far future period (2041–70) the model provides results that correspond with our preliminary expectations. the predicted line displays in three segments separately: 1) the moesz line may shift upwards (and northwards) to the carpathians; 2) in poland, a new moesz line may appear, which indicates the northern border of the distribution of species that can be established in poland; 3) and a southern border of the polish territories of optimal climate (so called ‘anti-moesz-line’) may appear in the northern side of the carpathians. besides the expansion in france, discrete territories in england, belgium, germany and bohemia are also predicted for the far future period. fig. 3. also points out that the carpathians (and subordinately the alps) will obstruct (as phytogeographical barrier) the expansion of the plant species bound to the moesz line. discussion of the improvement of model with artificial intelligence algorithms as the model results show, two of the three aforementioned modeling methods provide maps good enough (in terms of comparison of the observed and modeled distributions in the reference period) to display the impact of the climate change. since only a few climatic parameters were applied, the accuracy and reliability of the model can be improved by using some other climatic parameters (eg. sum of heat, length of vegetation period, length of the period endangered by frost) and edaphic parameters (eg. alkalinity, quantity of lime). although, more detailed and accurate inputs (eg. distribution maps, climate grid) could strengthen the model, it should also be noted, that the real improvement of the model can be reached only by the development of the modeling method. the cumulative distribution function should be calculated by statistical software to leave some percentiles from the minimum and maximum values of a certain climatic parameter. hence, only the climatic values that are bound exactly to the studied distribution area will be considered, since climatic extremes are mainly found near the distribution border will be left. further improvement of the abovementioned line model can be applied by using statistical or artificial intelligence (ai) methods to select the appropriate parameters from the infinite combination of the numerous climate parameters objectively. various ways can be used to determine the climate envelope, including simple regression, distance-based methods, genetic algorithms for rule-set prediction, and neural nets (ibáñez et al., 2006). to reduce subjectivity of parameters’ choice, logistic regression can be applied, which specifies the linear combination of climate parameters that determines the likelihood of distribution. another appropriate statistic method is cluster analysis, which explains the vector of climate parameters as points of a multidimensional space, and searches for a lower dimension which separates the distribution apart its surroundings. other clustering methods can be used, too. in comparison to statistical methods, applying artificial intelligence algorithms may results in much more improvement of the model. note, that some of them are black box methods, which can only answer the question what?/where?/when?, but not the question why?/how?. several artificial intelligence methods can be used for modeling the distribution of plant species or phytogeographical units, such as decision tree, evolutionary algorithm, and artificial neural net (ann). hilbert and ostendorf (2001) studied different forest types with ann, and the research of carpenter et al. (1999), özesmi and özesmi (1999), hilbert and van den muyzenberg (1999), özesmi et al.(2006), harrison et al. (2010), and ogawa-onishi et al. (2010) should be mentioned, since they modeled the distribution of species or communities with ann. evolutionary algorithm (which matches the climatic parameters with alleles and provides a process similar to natural selection with finite length) could conclude which parameters (and which extrema of them) are able to express the climate tolerance most of all. the result is therefore similar to the equations used in this research. this does not hold for ann, since a complicated neural net cannot be reduced to linear mathematical expressions. ann is similar to a real neural net densely furnished with axons, where the neurons are organized in layers. the algorithm has two main phases. learning phase is the first, when the program builds up and balances the internal structure of the net in such a way, that it is adjusted to the distribution of the plant. after the learning phase the model could determine the likelihood of presence at all the points of europe (for the reference period and the future periods, too). in contrary to ann, the aforementioned statistical and ai methods are not able to result in a map showing the potential distribution area (which is still the aim of modeling). on the other hand ann is the only method among them which is not able to separate the filtering of climate demands of species apart from the prediction. the essence of the learning phase is that based on the distribution and climate data the program forms a multilayered structure and it calculates the so called weights of every axon, iteratively. in the course of the timeconsuming, but finite learning phase the weights are continuously changed based on remodeling and error evaluation. a well parameterized ann with appropriate topology could model the future potential distribution area in a much more reliable way. the feedforward neural network (with multilayer perceptron model) seems to be the most suitable for distribution modeling. an ann with backporpagation training method is now under development in python programming language for 26 bede-fazekas (2013) arcgis software. input layer is connected to the climatic parameters (the number of neurons is determined by the number of parameters). the output layer has only one neuron which is able to predict a presence/absence data (1/0) or the likelihood of the absence (%). the training set is the part of the prediction set; the latter is the grid of the climate model (with more than 20,000 points). conclusion the modeling approaches of the distribution of plant species and phytogeographical units were studied and the conspicuous deficiencies of them were discussed. note, that in absence of ai supported modeling method, the used three simple models could provide spectacular results. modeling the moesz line yielded remarkable results, which are not perfectly the same as it was expected. it can be concluded that the northern carpathians will provide significant barrier for the plant species bound to the moesz line. in harmony to the studies of kovács-láng et al. (2008) – who stated that the speed of ecological processes is not synchronous with the speed of the climate change and therefore the mountains with latitudinal direction may become natural barriers – we should note that without human aid some of these species will not be able to get as far as poland. hence there is a risk that the predicted shift of the moesz line may be a prediction of the shift of only a virtual line. acknowledgement the author would like to express his gratitude to the two anonymous peer-reviewers for their advices. special thanks to levente horváth (corvinus university of budapest), levente hufnagel (corvinus university of budapest), anna czinkóczky (corvinus university of budapest), villő csiszár (eötvös loránd university), and tibor gregorics (eötvös loránd university) for their selfless assistance. the research was supported by the project támop-4.2.1/b-09/1/kmr-2010-0005. the ensembles data used in this work was funded by the eu fp6 integrated project ensembles (contract number 505539) whose support is gratefully acknowledged. references arundel, s.t. 2005. using spatial models to establish climatic limiters of plant species’ distributions. ecological modelling 182 (2), 159–181. bartholy, j., pongrácz, r. 2008. regionális éghajlatváltozás elemzése a kárpát-medence térségére (analysis of regional climate change in the region of the carpathian basin). in: harnos, zs., csete, l. klímaváltozás: környezet – kockázat – társadalom. szaktudás kiadó ház, budapest (in hungarian) bartholy, j., pongrácz, r., gelybó, gy. 2007. a 21. század végén várható éghajlatváltozás magyarországon (the predicted climate change in the end of 21 st century in hungary). földrajzi értesítő 56 (3-4), 147–168. 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(in hungarian) van leeuwen, b., tobak, z. 2008. gis solutions for belvíz monitoring: a case study in csongrád county, hungary. xii. symposium on geomathematics, i. croatianhungarian geomathematical conference, mórahalom tool for drought monitoring in the danube region – methods and preliminary developments journal of environmental geography 11 (3–4), 67–75. doi: 10.2478/jengeo-2018-0014 issn 2060-467x tool for drought monitoring in the danube region – methods and preliminary developments andreea bucur1, gregor gregorič2, aleš grlj3, žiga kokalj3, andreja sušnik2* 1department of geodesy and geoinformation, technische universität wien, gußhausstraße 27-29/e120, 1040 vienna, austria 2department of agrometeorology section, slovenian environment agency, ministry of the environment and spatial planning, vojkova 1b, 1000 ljubljana, slovenia 3slovenian centre of excellence for space sciences and tehnologies space-si, aškerčeva 12, 1000 ljubljana, slovenia *corresponding author, e-mail: e-mail: andreja.susnik@gov.si research article, received 1 october 2018, accepted 1 november 2018 abstract drought is a naturally recurring phenomenon of the climate system that affects virtually all regions of the world. during the past decades extreme droughts with extensive negative effects on ecosystems became evident also in the danu be region. at the moment regional capacity to monitor drought is still very diverse and not synchronised among different countries. in this is paper, we present a recently developed drought monitoring tool – the drought user service (dus) for the danube region using remote-sensing products which aims at offering a more accurate and in near-real-time monitoring via different drought indices. the dus was created as the monitoring tool of the risk-based paradigm, which seeks to give information in near real-time about the location and severity of droughts throughout the danube region. satellite remote sensing products meet the requirements for operational monitoring because they are able to offer continuous and consistent measurements of variables, which can be used to assess the severity, spatial extent and impacts of drought. in the dus three different variables – vegetation, soil moisture and precipitation – are monitored with earth observation products. the condition of vegetation and soil moisture is tracke d with two simple indicators computed as long-term anomalies of the ndvi and swi products made available through eu’s copernicus global land service. the importance of dus and of the developed methods for faster detection of drought onset as useful foundat ion for establishing a better pro-active drought management in order to mitigate the negative effects of drought in the region is discussed. keywords: drought monitoring, drought impacts, drought management, satellite data, drought user service introduction drought has been a recurrent phenomenon in the danube region and its characteristics in the last decades are changing. it has become more intense and is developing more frequently. according to recent findings related to climate change, drought is likely to become more frequent and severe in the 21st century in many regions of the world, especially in water-scarce and already vulnerable areas that include parts of europe (ipcc, 2014). in the current climate, summer water scarcity is already a problem in the danube basin but its duratio n and magnitude are projected to increase especially in the southern and eastern part of the danube basin (bisselink et al., 2018; van lanen and vogt, 2018). despite the impacts on the economy and welfare of people caused by drought in the last decades, drought is still not considered an issue of high priority, people remain reactive in their actions and any measures are carried out only when drought has already developed. in the last years, there have been important efforts both in the scientific and technical field in relation to drought. unfortunately, a universal definition of drought is difficult to formulate due to the range of drivers and impacts that a drought event may have (sepulrce-canto et al., 2012). drought projects increase the knowledge on drought in different research areas and regions, providing additional monitoring tools and management experiences for policy-makers and water related managers in the eu i.e. drought-r&spi (drought r&spi, 2015), dewfora (dewfora project, 2013), peseta (watkiss et.al., 2009) and regional cooperation programmes such as euroclima (european commission, 2018), as well as several national initiatives. findings from the projects have advanced the knowledge base with better access to information, guidelines and services on (van lanen et al., 2017): drought monitoring, prediction and early warning, drought impacts and links with the hazard, drought risk assessment, risk reduction and drought response and policy, and planning for drought preparedness and mitigation across sectors. as a result, a range of indicators is used to detect and monitor agricultural drought, which are typically based on meteorological observations and estimates from remote sensing and modelling. the status of drought monitoring in the danube region is still in its early stages, characterised by cross-border inconsistency with products that are often not delivered on time. furthermore, methodologies for drought risk assessment and drought impact assessment are not harmonised across the region. drought management in the region is reactive, dealing 68 bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. mainly with losses and damages, cooperation among key actors is missing and formal legislation considers drought only partially and insufficiently. aiming at overcoming these weaknesses was the main motivation for launching of the project dridanube – drought risk in the danube region (dridanube, 2018). the paper presents some of its results, focusing on a new monitoring tool – the drought user service (dus) that makes use of the earth observation operational products from the eu’s copernicus global land service: the soil water index (swi) and the normalized difference vegetation index (ndvi). swi and ndvi long-term anomalies can be used as indicators for operational drought monitoring and early warning across 10 countries in danube basin. the dus presents to the public near-real-time information on drought via an online portal: www.droughtwatch.eu. timely, relevant and reliable drought information will be vital for detection and alert systems at the core of response activities in the danube region. research area to provide context for the consideration of drought detection, an overview of the regional climate is given. the research area covers almost the entire catchment area of the danube river and includes the territories of 10 countries: czech republic, slovakia, austria, hungary, slovenia, croatia, bosnia and herzegovina, serbia, montenegro and romania (fig. 1). generally, most of the danube basin is dominated by a continental climate, only the western parts of the upper basin and its southwestern part are influenced by the atlantic climate or by the mediterranean climate, respectively. annual precipitation depends mainly on orographic features and ranges from less than 200 mm per year to over 2000 mm per year. the rivers fed by water and moisture from the wet mountains help to balance evapotranspiration deficits, typical for the pannonian plain and the delta, in the dry lowlands (danube regional project, 2012). eight extreme drought events that have occurred across various parts of the danube region since 2000 have caused extensive damage to natural ecosystems and diminution of agricultural production and in many countries also disturbance of surface and groundwater supplies. remote sensing data and drought indicators recently developed platform called drought user service (dus) is an innovative web-based tool for the viewing and analyses of the drought related spatial datasets. the purpose of the tool is to upgrade the systems for monitoring of the drought in the danube region with the goals of mitigating the effects of drought and preparing potential users for timely reaction. the development was followed a pre-set plan, roughly composed of three consecutive phases. first, we were interested in the ideas and demands of potential users. we collected these with a web-based questionnaire comprising of 35 questions related to the basic information about the user, information about their experience in working with earth observation data, and questions concerning the components of the planned system, its tools, and data usage (analyses). we have sent the questionnaires to all project partners and other potential users, including national hydrological and meteorological services, fig. 1 annual precipitation map (shades; average for period 1971-2000) and political boundaries (black line) of the region and countries, participating in preparation of drought user service (source of precipitation data: worldclim.org; fick and hijmans, 2017) bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. 69 environmental agencies, other governmental agencies, international and non-governmental organizations, and research institutions. 47 institutions from 10 european countries responded. the analysed results were translated into the priority scale of the requirements, based on the moscow method, in which the requisites are divided into four categories: must-have, should-have, could-have and will-not-have requirements (bittner and spence, 2004). dus offers near real-time information about drought conditions with two remotely sensed indices: the soil water index (swi) and the normalized difference vegetation index (ndvi). this section describes these indices, their usefulness and implementation for drought monitoring in the danube region. the data source for both swi and ndvi products are made available through the copernicus global land service (gls). soil water index (swi) anomalies for soil moisture monitoring in drought conditions soil moisture (sm) is an important element in the earth’s system. its key role in the hydrological, carbon and energy cycles and their interaction led to its recognition as an essential climate variable in 2010 by the global climate observing system (e.g. leghates et al., 2011; seneviratne et al., 2010). furthermore, soil moisture is one of the indicators used to monitor, forecast and characterise drought. operational online drought monitoring tools around the world incorporate information on soil water content from modelled and/or remote-sensing-based estimates: e.g. the us drought monitor, the european drought observatory (vogt et al., 2011), the african flood and drought monitor. sm estimates are available from in-situ measurements, atmospheric and hydrological models, and satellite imagery and are characterised by method-specific advantages and limitations (e.g. leghates et al., 2011; nghiem et al., 2012; petropoulos et al., 2015). the satellite-based sm products are most commonly retrieved from microwave activate and passive sensors (e.g. smos – kerr et al., 2010; smap – entekhabi et al., 2010; amsr-e – e.g. njoku et al., 2003; ers and ascat– e.g. wagner, 1998) and offer the advantage of continuous temporal and spatial measurements (in contrast to e.g. point-measurements from in-situ networks which are not representative over an area due to the high spatial variability of soil moisture). the copernicus swi product provides global daily information on moisture conditions at different soil depths at a spatial resolution of 0.1 degrees (paulik, 2017). the swi data used to calculate the swi anomalies displayed in dus uses as input the ascat-25km surface soil moisture (ssm), a remote-sensing product (bartalis et al., 2008) provided operationally in near real-time by the european organisation for the exploitation of meteorological satellites (eumetsat). the ascat scatterometer on board the metop satellites (metop-a and metop-b) is a real aperture radar that operates at 5.255 ghz (c-band) and uses six vertically polarised antennas for transmission and reception of long pulses that after several specific steps (as described in e.g. eumetsat, 2015; wagner et al., 2013) become backscatter coefficients (𝜎 0) given in units of decibels (db). exploring the underlying high sensitivity of microwaves to the water content in the most upper layer of the soil (12 cm) these backscatter measurements are then transformed into surface soil moisture estimates with the tu wien method by wagner et al. (1999a,b,c) originally developed for the ers-1/2 ami instruments and further improved by bartalis (2006, 2007) and naeimi et al. (2009a,b). however, besides soil moisture, the microwaves are sensitive also to other factors such as the surface roughness and vegetation cover; the tu wien’s ssm retrieval model is a change-detection model which minimises these effects by interpreting changes in backscatter (𝜎 0) over time as detailed in wagner et al. (2013). swi gives information on the moisture conditions available to plants in their root-zone which has proved to be useful for characterising agricultural drought (e.g. gouveia et al., 2009). based on the method proposed by wagner (1999b), the swi algorithm uses an infiltration model that describes as a function of time the relation between the soil moisture observed at surface and the profile soil moisture. thus, using a two-layer water balance model, the ssm observations are transformed into swi with eq. (1). swi(tn) = ∑ ssm(ti) e tn−ti tn i ∑ e − tn−ti tn i , for ti ≤ tn (1) where 𝑡𝑛 is the observation time of the current measurement and 𝑡𝑖 are the observation times (in julian days) of the previous measurements; all ssm observations made before 𝑡𝑛 are summed up and exponentially weighted. the factor 𝑇 determines the weights (e.g. for t = 5 the weight is equal to 0.135; where 10 is the number of days ssm was taken before 𝑡𝑛) and how much ssm observations taken in the past influence the current swi value. for near real-time operations, the swi can be calculated with a recursive formulation (eq. 2) (albergel et al., 2008, paulik, 2017): swit(tn) = swit (tn−1) + gaint(tn)(swi(tn) − swit(tn−1)) (2) where t_n and t_(n-1) are the observation times of the current and previous ssm measurements, respectively. agricultural drought follows the meteorological drought and is characterised by drying of soil which results in a reduction in vegetation growth and in crop and biomass production (mishra and singh, 2010; van lanen et al., 2017). in dus, long-term anomalies of swi are used as indicator of drought. the long-term anomalies are used, rather than current absolute values as they reflect better the positive and negative variations in soil water content in a historical context, and thus of drought conditions. these are computed daily (eq. 3) as the difference between the swi (t=10) value for a certain day (e.g. 1 march 2018) and the long-term average for the same day over values since 2007 up to the last full year (e.g. for a value in 2018 the period considered is 20072017; copernicus swi product is available only since 70 bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. 2007). before anomaly computation the data is masked for frozen soil and temporary water on the surface using the surface states flags (ssf) as described in paulik (2017). swianomalyt = swit − swi̅̅ ̅̅ ̅ (3) where swit is the swi value of day t of the current year, and swi̅̅ ̅̅ ̅ is the long-term average of swi. according to the definition of the swi, the swi anomaly represents values expressed as units of degree of saturation. in the dridanube’s drought user service the swi anomaly values are displayed as daily maps. the maps depict with brown shades the swi anomalies as percentage up to 25% less than long-term average and with blue shades up to 25% more than the long-term average; zero represents no change in soil moisture conditions from the long-term mean. the swi product has certain limitations, which have to be considered for the interpretation of swi anomaly indicator presented here. these are related to the model definition of the swi; e.g. soil texture that defines the relationship between value 𝑇 and soil depth is not taken into account, and therefore the availability of values which allows the user to select and compare the best data. also, evapotranspiration is not considered by the swi algorithm which can lead to false high values when precipitation and satellite observation times coincide and the rainfall evaporates rather than infiltrate into the deeper layers of the soil. furthermore, as already mentioned at the beginning, vegetation has a strong influence on the radar signal of which the annual cycle in the base product – the ascat ssm – is considered to be the same for each year; however, if this deviates significantly form the average the retrieval of ssm becomes biased. the swi product, as well as its underlying ascat ssm product, has been extensively validated in numerous studies against external data sets including in-situ soil moisture measurements in paulik et al. (2017 and all other studies therein referenced). the products show good correlations with both modelled and ground measurements, except arid areas and for the northern latitudes. the accuracy of the product was reached for 75% of the sites when the target was set to 0.1 m3/m3, while a target of 0.2 m3/m3 was obtained for 98% of sites (paulik, 2017). furthermore, the swi product has a good temporal consistency that reflects well the seasonal cycle with the exception of very dry conditions. the spatial consistency is also good, however, swi estimates are not reliable over high altitudes, dense forest and desert areas; and cannot be estimated for frozen conditions. normalized difference vegetation index (ndvi) anomalies for vegetation drought monitoring ndvi is the most straightforward way of detecting and monitoring vegetation from satellite measurements (anyamba and tucker, 2012) and represents the starting point of satellite-based indicators for drought monitoring. this simple metric has been present since the 1980s and was first formulated for avhrr imagery by tucker et al. (1979). given its early development almost 40 years ago, this indicator has been widely studied for its utility in various applications: e.g. land cover classification, agricultural monitoring, biomass estimation or is included as input in land-surface or biophysical models (anyamba and tucker, 2012); or combined with other variables into more advanced indices (e.g. the vegetation condition index by kogan and sullivan, 1993). ndvi has also proven to be valuable for detecting drought-induced stress to vegetation and therefore included in the handbook of drought indicators and indices– a general guide on commonly used drought indicators for identifying the spatial extend, onset, duration and severity of droughts meant for practitioners who deal with drought management (wmo and gwp, 2016). ndvi, an index without physical units, is calculated from measurements of the spectral reflectances in the red spectrum (red) and near-infrared (nir) regions of the electromagnetic spectrum (eq. 4) (brown et al., 2013). theoretically, the ndvi values range between -1.0 and +1.0, where an increased ndvi is a sign of biomass abundance, while a low ndvi marks the lack of vegetation or decrease of photosynthetic activity. ndvi = nir − red nir + red (4) the copernicus normalized difference vegetation index (ndvi) product (smets et al., 2018) are generated based on the spot/vegetation c3 and the proba-v c1 data separately. the ndvi values are provided for every 10-day period at a spatial resolution of 1/112 degrees (~ 1km), and represent the best measurement selected from 10 consecutive days based on the criteria detailed in swinnen et al. (2017). the usual way of using ndvi for drought detection and monitoring is to compute ndvi anomalies (anyamba and tucker, 2012). in dus, the ndvi anomaly indicator is based on the difference from the long-term mean which shows the current drought severity in a historical context. it is produced for every 10-day period and is calculated as the difference between a certain 10-day ndvi value (e.g. first decade of july 2017) and the long-term average (eq. 5) over values since 1998 (copernicus ndvi product available since 1998) up to the last full year (e.g. for a value in 2018 the period considered is 1998-2017). before anomaly computation, the data is masked for cloud and cloud shadow, snow or ice and water using the quality flags as described in smets et al. (2018). ndvianomalyt = ndvit − ndvi̅̅ ̅̅ ̅̅ ̅ (5) in eq. 5 ndvit represents the 10-day ndvi value of the current year, and ndvi̅̅ ̅̅ ̅̅ ̅ is the long-term average of ndvi. negative ndvi anomalies represent lower than average ndvi values and are an indicator for vegetation stress and lower than average photosynthetic activity. in dus, the anomalies are displayed as maps for every 10-day period (decade). the maps depict with brown shades the ndvi anomalies as percentage up to -25% less than long-term average and with green shades up to 25% more than the long-term average; zero represents no change of vegetation conditions from the long-term mean. bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. 71 similar to the swi product, the ndvi product is not free of shortcomings which are sensor dependent – the wellknown inability of optical sensors to penetrate through clouds; additional factors such as – variations in solar zenith and viewing angles, surface reflectance bidirectional effects, atmospheric conditions, topography, data dropouts in cold regions – also influence the ndvi values. a full description of how are these addressed is available in smets et al. (2018). the overall performance of the product is rated as “good” based on validation studies carried out against similar products e.g. the ndvi from modis /terra nasa and from avhrr/metop – eumetsat (cgls, 2018). results and discussion the drought monitoring tool dus (fig. 2), being developed within dridanube project, increases the amount of new data and improves accessibility of existing data used in predicting and managing drought and its effects. the combination of data, new tools and previous research (e.g. ceglar et al., 2012) enables the planning of more efficient control mechanisms, spatial interventions and management practices in the danube basin. on the other hand, dus serves the end users, such as various ministries, agencies, and farmers, to make decisions and take action on the ground. most of the service data covers the entire danube region and, due to their nature (mostly satellite data), they have great potential for further development and geographic expansion. this opens the possibility for the competent departments of different countries to engage at a higher level of cooperation between the integrated regions of one of the major river basins in europe. 18 requirements were created from the user survey. four of these are general, related to the availability of the service and user support. six requirements relate to the data, their quality, temporal and spatial resolutions, availability basic cartographic data and auxiliary data. the respondents requested eight usability requirements, referring to the interaction of the user with the service (hasenauer et al., 2017). when the initial user requirements were met, the project consortium followed up with the user trainings where the service has been reviewed. the collected feedback was later reviewed, categorized and implemented. the results of the survey were the basis for the design of the technical solution. the drought user service is implemented with a combination of modern tools and technologies for web application development. the graphical user interface is composed with the html5 markup language and css3 cascading style sheets. the service is written in the javascript programming language and the developed in aurelia framework. the use of online maps is enabled through the openlayers 4.6.4 library, and mapserver 7.0.7 platform is used to display the drought-related data provided through our own web map service (wms). the technologies used facilitate potential service extensions and long-term compatibility with other web tools. they are also available without licencing fees, have a wide range of users, and are actively developed and updated in line with modern trends. the web interface displays three types of data. the first type includes the basic cartographic layers: google maps (obtained 2018), openstreet map (osm, 2018) and the satellite image mosaic, based on sentinel-2 data and fig. 2 appearance of the drought user service portal 72 bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. provided by eox gmbh (eox, 2017). the second type includes the various vector layers of administrative boundaries at different nuts levels for the area of the danube river basin (eurostat, 2018). the last type are raster data layers for the study of drought at a range of temporal and spatial resolutions, provided by various institutions. these form the core of the planned upgrade of the system, which will include the analysis of drought and its impact, and provide a drought early warning system. additional data will therefore include information layers developed during the project. these will show the state of drought and related phenomena. the system is designed modularly and enables quick and easy integration of new data; either in the application itself or through online services for displaying and transmitting geographic information, e.g. wms, web coverage service (wcs), web feature service (wfs). in the dus first observational year drought index swi and vegetation index ndvi showed good spatial matching. in figure 3. we see long-term anomalies of swi index from may to september 2018 with 1-month intervals and in figure 4. long-term anomalies of ndvi index for the same time frame as swi index. in may 2018 swi showed that areas with a level of soil moisture saturation lower than long-term average were scattered across danube area. in same time period vegetation index ndvi showed higher values than long-time average across danube region which are mainly caused by the earlier development of green mass due to higher temperatures in spring in this area. in june swi index increased in almost all investigated areas and especially in north and west became positive or higher than the long-term average. ndvi index in june lowered and in some areas in the north, central and east region became negative and showed good correlation with swi index. in july and august situation changed and swi index in the north part of the region become negative, especially deep in the czech republic. at the same time index rises in south and east areas and became much higher than the long-term average in romania, bulgaria and serbia. ndvi index in july and august stay in negative zone in northern parts of the region and slowly worsened and spread in the west and central parts. at the same time in the south and east parts index became positive which correlate with swi index. in september swi index slightly improved in almost all investigated areas with exception of the areas along east adriatic coast and central danube region, while ndvi index showed more negative anomalies in the north and central parts and less positive in east and south parts of the region. the goal of development is to take a step further from the creation of a web browser. the dus therefore enables the user to analyse and compare the displayed data. it is possible to overlay multiple layers, modify their transparency, and remove the selected layer to display underlying layers. the user can query the values of individual pixels or display and export a timeline graph for the selected pixel. users can also download data to a desktop computer and analyse them in a geographic information system. when selecting a vector layer object, the records in the attributes table of this object are displayed. individual data layers are provided with the basic descriptive information while descriptions that are more detailed are accessible from the application in the form of fact sheets. these describe the purpose, usability, the production method, technical information and product quality of an individual data layer. the dridanube project’s objective is to create a framework for relevant stakeholders in the danube region to increase their capacity to prepare better in case of drought events; in other words, moving from the traditional post-event crisis management to a pro-active risk-based management of droughts which includes several actions such as: preparedness, monitoring, riskmitigation and response. as presented in this paper the fig. 3 swi long-term anomalies on 1st of: may, june, july, august and september 2018 over the danube region: brown shades represent lower than average soil moisture conditions and blue shades represent higher than average soil moisture conditions. bucur et al. 2018 / journal of environmental geography 11 (3–4), 67–75. 73 two indices were selected based on their well-known potential to characterised droughts. however, beside the limitations determined by their production (associated with sensor type, algorithm etc.), it is recognised that no one indicator or index can fully capture the complexity of droughts (e.g., hayes et al., 2012). additionally, in the dus only long-term anomalies are available at the moment, however different other reference periods could be considered (10-days, weekly, monthly) and further investigated for their ability to monitor drought effects for example in relation to land cover types (e.g., crop types). also, although the whole period available is considered for the calculation of ndvi and swi anomalies, 19 and 11 year, respectively, it might still not be representative for drought events in the region. considering different 𝑇 values (at the moment 𝑇 = 10 is used) for calculating anomalies could also be explored over different areas and land-cover types within the danube region. furthermore, one needs to take into account limitations of the earth observation products. for ascat surface soil moisture, the input of swi, long-term positive trends have been observed over europe especially located close to large cities. these positive trends in soil moisture, and thus backscatter, are likely caused by expansion of urban areas, where multiple scattering increases backscatter, and possibly radio frequency interference. currently, tu wien is further investigating the source of these trends and how to correct for them. in recent years, an increased demand for information at finer spatial resolution (field size) has emerged as in the case of agriculture monitoring. in the dus, we have also presented for the first time swi anomalies at 1 km spatial resolution which is based on the original swi anomaly indicator downscaled with parameters calculated from sentinel-1. this approach combines the advantages of the sentinel-1 high spatial resolution and that of the ascat high temporal revisit time and show promising results as described in bauermarschallinger et al. (2018); the product is currently being prepared for operational dissemination through the copernicus gls (2018). conclusion no single source of information is authoritative and comprehensive to identify potential drought area alone, especially given the climatological heterogeneity within the danube basin. the dus brings to the drought practitioners in the region indicators based on earth observation products that offer information on the current status of drought and enables them to compare current situation to past drought episodes. in addition to the near real-time monitoring, the portal also makes available the results of the impact and risks assessments carried out within the scope of the project. conclusions on the drought situations are most confidently when many or all factors indicate a similar situation of dryness in a region. any reduction of ambiguity associated with data and information used by dus contributes to an improved linkage between early warning and early response. the drought monitoring approach improved by dus through the integration of satellite data and developed impact databases can form the basis for decision support systems at a national level for producing reliable and useful information that is regional in scope and relevant for local decision-making. acknowledgements this work was made possible by dridanube project in the frame of interreg danube transnational programme, which is co-funded by european union funds (erdf, ipa). we thank project partners, associated project partners and involved stakeholders for their support. acknowledgements to dr. mariette vreugdenhil (tu wien) for sharing her latest findings on positive trends observed in the ascat soil moisture product. fig. 4 ndvi long term anomalies for the 1st decade (1-10) of months: may, june, july, august and september 2018 over the danube region: brown shades represent lower than average vegetation conditions and green shades represent higher than average vegetation 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discussion conclusion acknowledgements references temporal relationship of increased palaeodischarges and late glacial deglaciation phases on the catchment of river maros/mureş, central europe journal of environmental geography 14 (3–4), 39–46. doi: 10.2478/jengeo-2021-0010 issn 2060-467x temporal relationship of increased palaeodischarges and late glacial deglaciation phases on the catchment of river maros/mureş, central europe tamás bartyik1*, györgy sipos1, dávid filyó1, tímea kiss1, petru urdea2, fabian timofte2 1geomorphological and geochronological research group, department of geoinformatics, physical and environmental geography, university of szeged, h-6722 szeged, egyetem u. 2-6, hungary 2department of geography, west university of timișoara, b-dul. vasile. parvan nr. 4, 300223, timișoara, romania *corresponding author, email: bartyikt@geo.u-szeged.hu research article, received 5 october 2021, accepted 19 october 2021 abstract river maros/mureş has one of the largest alluvial fans in the carpathian basin. on the surface of the fan several very wide, braided channels can be identified, resembling increased discharges during the late glacial. in our study we investigated the activity period of the largest channel of them, formed under a bankfull discharge three times higher than present day values. previous investigations dated the formation of the palaeochannel to the very end of the pleistocene by dating a point bar series upstream of the selected site. our aim was to obtain further data on the activity period of the channel and to investigate temporal relationships between maximum palaeodischarges, deglaciation phases on the upland catchment and climatic amelioration during the late pleistocene. the age of sediment samples was determined by optically stimulated luminescence (osl). the investigation of the luminescence properties of the quartz extracts also enabled the assessment of sediment delivery dynamics in comparison to other palaeochannels on the alluvial fan. osl age results suggest that the activity of the channel is roughly coincident with, but slightly older than the previously determined ages, meaning that the main channel forming period started at 13.50±0.94 ka and must have ended by 8.64±0.82 ka. this period cannot directly be related to the major phases of glacier retreat on the upland catchments, and in terms of other high discharge channels only the activity of one overlaps with a major deglaciation phase at ~17-18 ka. based on these, high palaeodischarges can be rather related to increased late glacial runoff, resulted by increasing precipitation and scarce vegetation cover on the catchment. meanwhile, the quartz luminescence sensitivity of the investigated channel refers to fast sediment delivery from upland subcatchments. therefore, the retreat of glaciers could affect alluvial processes on the lowland by increasing sediment availability, which contributed to the development of large braided palaeochannels. keywords: osl dating, river maros/mureş, deglaciation, luminescence sensitivity, sediment delivery introduction according to starkel (2002, 2007) and vandenberghe (2008), in eastern and northern europe the periods of the most intensive fluvial activity can be related to the beginning of interstadials, partly as a consequence of the accelerated retreat of ice sheets and mountain glaciers. this hypothesis however needs to be attested at different catchments at different latitudes (antoniazza and lane, 2021). the key to this question is to find relationships between archives located on upland catchments and on alluvial fans. alluvial fans are major elements of the central part of the carpathian basin, and as such research related to these geomorphological units has a well-established literature in hungary (e.g. gábris, 1995; gábris and nádor, 2007; mezősi, 2011; kiss et al., 2015). among these sedimentary bodies the maros/mureş alluvial fan is one of the largest ones, and special in several respects: fluvial activity has been the dominant process up till the river regulation works and this is recorded by a complex set of palaeochannels; parts of the river’s upland catchment were affected by glaciation during the last glacial maximum and the late glacial. consequently, the alluvial fan is an excellent candidate for investigating upland–lowland interactions under the changing environment of the late pleistocene and the holocene. the evolution of the maros/mureş alluvial fan, the discharge and age of its palaeochannels have been extensively studied by previous authors (katona et al., 2012; sipos, 2012; sümeghy et al., 2013; kiss et al., 2013, 2014, 2015; sümeghy, 2014). a great number of paleodrainage directions were identified, being active from the late glacial to the early holocene (kiss et al., 2013, 2015; sümeghy, 2014). based on the reconstruction of the channels, the discharge and sediment transport capacity of the river increased significantly during this period. bankfull discharge calculations suggest that by the end of the pleistocene, the river was several times larger than today, and its dimensions steadily decreased during the holocene (kiss et al., 2014). mailto:bartyikt@geo.u-szeged.hu 40 bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. according to kiss et al. (2014) and sümeghy (2014), the highest bankfull discharge palaeochannels were occupying the northern half of the alluvial fan and were active between 15.2±2.0 ka and 9.6±1.3 ka (fig. 1b). these channels had mostly a braided pattern, and the largest of them, located near orosháza (palaeochannel “d” on fig. 1b) could have a bankfull discharge of ~2600 m3/s (katona et al., 2012). during the transition from the late glacial to the holocene, only slight variations can be detected in bankfull discharge values (kiss et al., 2015; sümeghy, 2014). previous research has shown that climate change played a major role in affecting water and sediment yields, and thus determining fluvial aggradation and erosion processes (vandenberghe, 2008; gábris, 2013). for example, the climatic fluctuations of the pleistocene and parallel variations of runoff and vegetation cover resulted a cyclic change in the activity of eastern european sub-basins, which could lead to the formation of sediment pulses (e.g. starkel et al., 2007, antoniazza and lane, 2021). furthermore, changing runoff and sediment conditions could also affect the number of sediment cycles observed along rivers. similar processes were hypothesised for river maros/mureş (sipos, 2012), draining the waters of several mountain ranges of the eastren and southern carpathians, which were heavily glaciated during the pleistocene (urdea, 2004). the repeated retreat of glaciers could alter both the water and sediment discharge of the river (sipos, 2012). recent surface exposure dating (sed) results in the northern and southern valleys of the retezat mts. (southern carpathians), being the highest mountain range on river maros/mureş catchment, suggest that the maximum extent of glaciers and the onset of deglaciation occurred at ~20-21 ka, the same as in the rest of europe. deglaciation in the area was uneven, and several separate stages can be identified on the basis of the age of moraines at different altitudes (ruszkiczayrüdiger et al., 2016, 2017, 2021). however, due to rapid glacier retreat, these phases partially overlap (ruszkiczay-rüdiger et al., 2021). based on the measurements of ruszkiczay-rüdiger et al. (2016), the youngest moraines in the northern valleys of the retezat mts. are related to a minor glacial advance at ~14.5 ka during the gi-1 interstadial (bølling/allerød). there is no direct evidence for later glaciation cycles in the area, i.e the last moraines in the area have been stable for nearly 13.5 ka (ruszkiczay-rüdiger et al., 2016). based on the above, the major aim of the present study was to investigate the possible temporal linkages between late glacial deglaciation processes on the upland catchment and lowland fluvial processes related to river maros/mureş, with special emphasis on the largest palaeochannel identifiable on the alluvial fan of the river. besides, by using a novel approach we attempted to assess the dynamics of sediment delivery from upland sediment sources. study area and sampling river maros/mureş is the fourth largest river of the carpathian basin, and it is the largest tributary of the tisza river (fig. 1a). the area of its catchment is ~30,000 km2, it drains the waters of the transylvanian basin, and it is bordered by the apuseni mountains and the eastern and southern carpathians. the highest range on the catchment, affected greatly by pleistocene glaciation is the retezat mts., with a maximum height of 2509 m (fig. 1a). the northern, western and major southern exposure valleys of the mountain range are all drained to river strei, a tributary of the maros/mureş. the actual mean discharge of the river at its lowland section is 160 m3/s, while its bankfull discharge can reach 850 m3/s (fiala et al., 2007). samples for osl dating were collected from sediments related to the largest palaeochannel generation (palaeochannel “d”), located north of the axis of the alluvial fan, along the kétegyháza ‒ orosháza ‒ hódmezővásárhely line. this channel was also investigated by kiss et al. (2014) and sümeghy (2014) at orosháza (fig. 1b). based on their data, the channel was active between 12.4±2.1 and 9.6±1.3 ka (sümeghy, 2014). the channel is characterised by a change from a braided to a meandering channel pattern near orosháza and a braided pattern again on its lower reaches. the width of the channel can reach up to 1000 m, its average bankfull depth was estimated to be 2.8 m on the basis of topographical and shallow geophysical surveys (katona et al., 2012). the bankfull discharge of the palaeochannel was estimated to be ~2600 m3/s (katona et al., 2012; sümeghy, 2014). sediment samples were collected 30 km downstream of the orosháza site (kiss et al., 2014) near the former confluence with the palaeo-tisza river (fig. 1b). a total of four samples were collected from two sampling sites in a recently opened sand quarry, located in the area of the former village of csomorkány, northeast of the town of hódmezővásárhely (fig. 1b). the first sampling point (csom1) represents the point bar on the left bank of the former palaeochannel, while at the second sampling point (csom2) an aeolian sand sheet with parabolic dune forms was sampled (fig. 1c). based on the topography and the dominant wind direction (n-nw), the aeolian sediments investigated were blown out from the abandoned channel, and can indicate the minimum age of fluvial activity. at the first csom1 profile, coarse grain crossbedded deposits were observed, interbedded with thin silty layers, referring to a cyclic deposition during channel development (fig. 2). the first sample (osz1468) was collected at 81.5 m asl., from a cross-bedded, coarsegrained fluvial deposit, while the second sample (osz1467) was taken from a sand layer between two silty deposits (fig. 2). the third sample (osz1466) was collected at 82.5 m asl., from, above the topmost silt layer. at the second sampling point (csom2), one sample was collected (osz1469) at a depth of 70 cm compared bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. 41 to the ground surface level (~85.2 m asl), from a medium to coarse-grained, homogeneous, unstratified sand deposit. based on its stratigraphic features the deposit was interpreted as an aeolian sand sheet; its material was presumably blown out of the already abandoned channel (fig. 2). fig. 1 a) location of the maros/mureş alluvial fan and the retezat mts. in the carpathian basin; b) position of palaeochannels on the alluvial fan (after sipos, 2012), those being active during the late glacial are marked by capital letters (following the system of kiss et al., 2015), and the location of the csomorkány sampling site; c) dem and most important geomorphological features of the csomorkány sampling site. fig. 2 the vertical position of sampling profiles and sampling points with the obtained osl ages and quartz sensitivity values. methods the geomorphology of the study area was studied on the basis of a topographic map (scale of 1:10000). geomorphological features were mapped using esri arcgis 10.4.1 (fig. 1c). at both sites, osl samples were taken from an open profile of the sand quarry using an eijkelkamp undisturbed sampler with light tight steel cylinders. an additional ~500 g of sediment was taken from around the osl samples to determine the environmental dose rate necessary for age calculation. as most of the surface sediments have been removed by quarrying, the original altitude of the terrain could only be estimated using topographical maps (scale: 1:10000) made well before the opening of the quarry. the exact elevation of sampling points (m asl) was measured using an rtk gps. optically stimulated luminescence (osl) is a method to investigate the age of the last deposition of sediments, and thus it is suitable to date fluvial activity periods, for example the formation of palaeochannels and point bars (rittenour, 2008). although, the method is primarily used for dating, there is a number of additional information provided by luminescence measurements that can help to refine geomorphological reconstruction. one of these is measuring the osl response to unit radioactive dose, by which the so called luminescence sensitivity, a parameter largely dependent on the petrological background and the sedimentation history of grains (sawakuchi et al., 2018, bartyik et al., 2021a), of the investigated mineral extract (this time quartz) can be assessed (gray et al., 2019). the preparation of the collected osl samples has followed usual laboratory techniques (mauz et al., 2002; sipos et al., 2016). first a 1 cm thick layer was removed from each end of the sampling cylinders. the samples were then dried to constant weight to determine in situ water content. the coarse-grained sand was separated using sieves of 150-200 µm and 220-300 µm. the most abundant fraction was then subjected to acid treatment, using 10% hcl to remove the carbonate content and 10% 42 bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. h2o2 to remove the organic matter content of the sample. the quartz fraction, essential for osl measurements, was separated using an adjustable density heavy liquid (lstfastfloat). the separated quartz minerals were subjected to a 40% hydrogen fluoride (hf) treatment for further purification and accurate calculation of the dose rate. the clean quartz grains were spread on a 1 cm diameter stainless steel disc using a 2 mm mask. for luminescence sensitivity measurements, grains were placed in 1 cm diameter stainless steel cups. the weight of the samples in the sample carrier was recorded using an analytical balance for the mass normalisation of results later. equivalent dose (de) and sensitivity measurements were both carried out using a risø tl/osl-da-20 luminescence reader. irradiation was made using a calibrated 90sr/90y beta source. luminescence intensities were detected through a hoya u-340 filter placed between the sample and the photomultiplier. the single aliquot regeneration (sar) protocol, developed by wintle and murray (2006), was used to determine the de of quartz samples. prior to de measurements a combined preheat and dose recovery test was performed on two samples (osz1466, osz1469) in order to determine optimal heating parameters. based on the dispersion, skewness and kurtosis of single aliquot results, the minimum age model (mam) was used to calculate sample equivalent dose values (galbraith et al., 1999; arnold et al., 2007). the luminescence sensitivity of samples was assessed using both osl and tl (thermoluminescence) responses for the same dose. measurements and evaluation followed the steps of nian et al. (2019) and bartyik et al. (2021a). the previously bleached samples were irradiated with a uniform dose of 24 gy. osl sensitivity was determined using the first 0.5 s of the continuous wave osl (cw-osl) luminescence decay curves. for calculating tl sensitivity, the signal obtained in the 80-120°c range (tl 110°c peak) of the growth curve was integrated. these data were then normalised by sample mass, dose and background. the error of sensitivity results is expressed both using standard error (se) and standard deviation (sd), the later one is put in parentheses hereinafter. environmental dose rate (d*), which is also essential for the calculation of the osl age, was determined by measuring the specific activity of sediment samples using a canberra xtra extended range gamma spectrometer equipped with a coaxial type germanium detector. the cosmic dose rate was calculated using the empirical formula of prescott and hutton (1994). results and discussion luminescence properties the preheat and dose recovery tests on sample osz1466 and osz1467 resulted very high recuperation values, close to the 5% threshold at all temperature ranges investigated (fig. 3). in such cases, as suggested by murray and wintle (2003), an additional high temperature stimulation (280°c) (hot bleach) was added to the sar protocol at the end of each measurement cycle. fig. 3 preheat and dose recovery test results for samples osz1466 and osz1469. consequently, the error caused by high recuperation values could be significantly reduced. based on the combined preheat and dose recovery tests, a 200°c preheat temperature was chosen for subsequent measurements, as samples passed other sar criteria (wintle and murray, 2006) also at this temperature (fig. 3). during sensitivity measurements, each sample produced an adequate amount of luminescence signal. the lowest sample in the csom1 section, osz1468, had a sensitivity of 132±34(84) cts/mg/gy, while the two samples above (osz1467, osz1466) had slightly lower values: 85±12(30) cts/mg/gy and 105±13(33) cts/mg/gy (table 1). sample osz1469 with an aeolian origin had the highest cw-osl sensitivity, being 155±27(66) cts/mg/gy. in terms of the tl 110°c peak sensitivity values, no significant differences could be identified at the csom1 profile (table 1). osz1466 yielded 1517±148(419) cts/mg/gy, osz1467 1447±106(300) cts/mg/gy and the lowest sample osz1468 1530±211(597) cts/mg/gy. however, the osz1469 sample from csom2 had a tl sensitivity of 2160±290(821) cts/mg/gy, which is significantly higher than in the case of the previous samples (table 1). after plotting the two sensitivity parameters against each other it became possible to compare quartz sensitivities to previous data obtained from other sediments related either to the maros/mureş, tisza or danube rivers (fig. 4) investigated by bartyik et al. (2021a). the detailed comparison of the cw-osl and tl 110°c peak sensitivities of the csomorkány quartz with the results of the carpathian basin fluvial samples (bartyik et al., 2021a), reflects that the csom1 section samples represent a transitional sensitivity level (fig. 4). bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. 43 it is also clear that the csom1 samples have considerably lower cw-osl values compared to the mean of all other maros/mureş sediments (175±10(67) cts/mg/gy) from other palaeochannels on the alluvial fan (bartyik et al., 2021a; fig. 4). this average value is only approached by the aeolian sample in the csom2 profile (osz1469). the same trend can be identified concerning the tl 110°c peak sensitivity. in this case the average value of csom1 samples, being 1476±86(437) cts/mg/gy is also significantly lower than the average tl sensitivity of other samples from the alluvial fan, being 2193±146(506) cts/mg/gy. from among the samples studied by bartyik et al. (2021a) one represented the same palaeochannel, but was collected at the orosháza site investigated by sümeghy (2014). this sample plots very close to csom1 samples and just like these it can clearly be differentiated from other maros/mureş alluvial fan samples (fig. 4). consequently, the low sensitivity of samples is not site specific, but can be characteristic for the entire palaeochannel. table 1 dose rate, equivalent dose and sensitivity data of the investigated samples. lab id osz1466 osz1467 osz1468 osz1469 altitude of the sample [m asl] 82.5 82 81.5 84.8 water content [%] 10±2 10±2 10±2 10±2 u [ppm] 1.35±0.02 1.47±0.02 1.21±0.02 1.51±0.02 th [ppm] 4.81±0.11 5.11±0.12 4.33±0.11 5.27±0.12 k [ppm] 1.34±0.04 1.26±0.04 1.14±0.03 1.21±0.04 d* [gy/ka] 1.85±0.04 1.65±0.04 1.60±0.04 1.84±0.04 de [gy] 19.97±1.73 21.38±1.94 21.66±1.44 15.93±1.46 age [ka] 10.80±0.97 12.95±1.25 13.50±0.94 8.64±0.82 cw-osl sensitivity mean±se(sd) [cts/mg/gy] 105±13(33) 85±12(29) 132±34(84) 155±27(66) tl 110°c peak sensitivity mean±se(sd) [cts/mg/gy] 1517±148(419) 1447±106(300) 1530±211(597) 2156±290(821) fig. 4 cw-osl and tl 110°c peak sensitivity results compared to the sensitivity results of bartyik et al. (2021a). values measured for the fluvial samples at the csomorkány site and at the upstream orosháza site are circled with a dashed line. 44 bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. low sensitivity values experienced in case of palaeochannel “d” can be explained by two factors. firstly by the increased contribution of catchments rich in low sensitivity quartz to the sediment mixture of the palaeochannel. for example, it was demonstrated by bartyik et al. (2021b) that the quartz sensitivity in a major tributary of the maros/mureş (river strei), collecting the sediments of the northern and southern slopes of the retezat mts., is lower than the sensitivity of quartz from other catchments. consequently, after the deglaciation this catchment could provide a considerable input to the main river. secondly, as the number of sedimentary cycles can increase significantly the sensitivity of quartz grains (see e.g. preusser et al., 2006; fitzsimmons, 2011), the fast transfer of sediments from the upper catchments to the alluvial fan can also explain the low sensitivity of fluvial sediments related to palaeochannel “d”. taking into consideration that the redeposited aeolian sample at the investigated site (osz1469) has higher sensitivity than fluvial ones, it seems probable that the second factor, i.e. limited sediment recycling due to fast sediment transfer can be the main reason behind low sensitivity values of palaeochannel “d”. osl quartz ages the lowermost sample (osz1468) from the csom1 profile gave an age of 13.50±0.94 ka. a very similar result was obtained for the sample above (osz1467), giving an osl age of 12.95±1.25 ka, meaning practically that the two layers can be related to the same fluvial cycle. these ages refer to channel sediment deposition during the gi-1 interstadial. the topmost sample at the csom1 profile is significantly younger and refers to another depositional event, in the early holocene at 10.80±0.97 ka. these data, by considering the uncertainty of osl ages refer to a channel forming fluvial activity between ~14.5 and 9.8 ka ago (table 1., fig. 5). the results of the samples from the csom1 profile are mostly in agreement with the osl ages measured by kiss et al. (2015) and sümeghy (2014) on the upstream part of the same palaeochannel, determining an activity period between 12.4±2.1 and 9.6±1.3 ka. however, the present results slightly push back the start of major channel development along the investigated channel generation. sample osz1469, collected from the csom2 profile gave an osl age of 8.64±0.82 ka, which is considerably younger than the fluvial records of the csomorkány sampling site. during this period, the maros/mureş already shifted to the southern part of its alluvial fan (kiss et al., 2015). the stratigraphy and the geomorphological setting suggest that aeolian activity started in the area after the avulsion, as the channel became dry. the higher luminescence sensitivity sample (osz1469) also refers to aeolian redeposition which can significantly increase sensitivity values as demonstrated by fitzsimmon (2011) or sawakuchi et al. (2011). fig. 5 deglaciation phases in the northern valleys of the retezat mts. (ruszkiczay-rüdiger et al., 2016, 2021). b: palaeochannel activity periods on the maros/mureş alluvial fan (this study and sümeghy, 2014) and the bankfull discharges of channels (katona et al., 2012; kiss et al., 2014), fitted to benthic δ18o records (lisiecki and raymo, 2005). bartyik et al. 2021 / journal of environmental geography 14 (3–4), 39–46. 45 relationship of fluvial activity and deglaciation history if the activity periods of palaeochannels along with their attributed discharge values determined by kiss et al. (2015) and katona et al., (2012) are compared to the deglaciation phases of the retezat mts., one can see that the lowest bankfull discharge palaeochannel “a1” coincides with the m1 (~22-20 ka) and m2 (~17-18 ka) deglaciation periods of the late glacial (fig. 5). the elevation of m1 and m2 terminal moraines on the northern and southern slopes is 1080-1130 m asl. and 1220-1610 m asl (ruszkiczay-rüdiger et al., 2021), respectively, equalling to equilibrium line altitudes (ela) of 1830-1900 m and 1960-1970 m (ruszkiczay-rüdiger et al., 2016). this means that the most intensive retreat of glaciers did not have a significant effect on the discharge of river maros/mureş on the alluvial fan. the activity of channels with significantly higher discharges (palaeochannels: a2, b, c and d) can rather be related to deglaciation phases m3 and m4, occurring after minor glacier advance, leaving behind moraines at 1700-1880 m and 2050-2010 m asl, respectively, i.e. the ela ascended to ~2040-2200 m asl. in this period (ruszkiczay-rüdiger et al., 2017; 2021). this also means that during these late phases the condition of glaciers affected only the top most region of the mountain range, thus melting could not significantly contribute to the high discharges experienced in terms of the palaeochannels on the alluvial fan (fig. 5). moreover, palaeochannel “c” with a bankfull discharge of ~2500 m3/s was dated to gs2 stadial, a cold period presumably resulting glacier advance anyway. although the activity of the now investigated palaeochannel “d” started during deglaciation phase m4, it also coincides with the gi-1 interstadial (rasmussen et al., 2014), notable of large discharges on other carpathian basin rivers as a matter of precipitation increase (see e.g. gábris, 1995, gábris and nádor, 2007). at the same time, the braided pattern of palaeochannels from this period suggests a high availability of sediments on the catchment that can be partly caused by coarse grain sediments released from previously glaciated valleys on the upland catchment (antoniazza and lane, 2021), and the time lag between the adaptation of vegetation to climate change (vandenberghe, 2008). both leading to the initiation of sediment pulses towards the alluvial fan. thus, due to the rapid warming (gi-1) and cooling (gs-1) of the climate, coarse grain sediments accumulated previously as a matter of limited runoff could be mobilised on the upper catchment. consequently, deglaciation rather contributed to the changing sediment regime, the development of sediment pulses and the changing style of river channels on the alluvial fan. conclusions the obtained ages pushed back the activity of the largest palaeochannel (palaeochannel “d”) on the alluvial fan of river maros/mureş by approximately 1.0 ka compared to earlier studies. still, the ages between 13.5±0.9 (this study) and 9.6±1.3 ka (kiss et al., 2014), representing the channel forming period of the investigated palaeochannel, cannot be directly related to the major deglaciation phases of the retezat mts. thus, the extremely high discharge inferred from the studied channel occurred as a matter of increased precipitation during the gi-1 interstadial and the delayed appearance of vegetation cover, both contributing to very high runoff values. concerning other, relatively high discharge palaeochannels (a2, b, c) activity periods overlap with the final deglaciation phases of the retezat mts, but these final phases affected very limited areas on the upland catchment, and therefore, could not significantly contribute to increased runoff. though deglaciation did not affect significantly plaeodischarge values, sediment availability supposedly increased during the climatic amelioration. from upland sub-catchments a considerable amount of coarse grain sediment could be mobilised after the retreat of glaciers, and consequently shallow, braided channels could develop on the alluvial fan. increased sediment delivery was also supported by the measured luminescence sensitivity values. sediments associated with the fluvial activity of the investigated palaeochannel exhibit lower quartz luminescence sensitivity than any other previously investigated palaeochannels on the maros/mureş alluvial fan. low values could be caused by 1) more active sediment supply from previously glaciated subcatchments rich in low luminescence sensitivity quartz grains, and 2) faster delivery of grains towards the alluvial fan, whereby the grains were not subjected to several cycles of deposition which could enhance their sensitivity. acknowledgements this work was supported by the hungarian national research, development and innovation office (otka k119309 and k135793) and by the únkp-21-4-szte447 new national excellence program of the ministry for innovation and technology from the source of the national research, development and innovation fund. references antoniazza, g., lane, s.n. 2021. sediment yield over glacial cycles: a conceptual model. 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(ed.) 2012. past, present and future of the maros/mureş river. university of szeged. p. 212. sipos, gy., kiss, t., tóth, o. 2016. constraining the age of floodplain levels along the lower section of river tisza. hungary. journal of environmental geography 9(1-2), 39–44. doi: 10.1515/jengeo-2016-0006 starkel, l. 2002. younger dryas-preboreal transition documented in the fluvial environment of polis rivers. global and planetary change 35, 157–167. doi: 10.1016/s0921-8181(02)00133-9 starkel, l., gębica, p., superson, j. 2007. last glacial–interglacial cycle in the evolution of river valleys in southern and central poland. quaternary science reviews 26, 2924–2936. doi: 10.1016/j.quascirev.2006.01.038 sümeghy, b., kiss, t., sipos, gy., tóth, o. 2013. a maros hordalékkúp felszíni képződményeinek geomorfológiája és kora (geomorphology and age of the surface formations of the maros alluvial fan). földtani közlöny 143/3, 265–278. (in hungarian) sümeghy, b. 2014. a maros hordalékkúp fejlődéstörténeti rekonstrukciója (historical reconstruction of the evolution of the maros alluvial fan). phd dissertation, szegedi tudományegyetem. (in hungarian) urdea, p. 2004. the pleistocene glaciation of the romanian carpathians, in: quaternary glaciations – extend chronology, ehlers, j., gibbard, p.l. (eds.), 2004 elsevier b.v. 301–307. vandenberghe, j. 2008. the fluvial cycle at cold-warm-cold transitions in lowland regions: a refinement of theory. geomorphology 98, 275–284. doi: 10.1016/j.geomorph.2006.12.030 wintle, a.g., murray, a.s. 2006. a review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols. radiation measurements 41, 369–391. doi: 10.1016/j.radmeas.2005.11.001 https://doi.org/10.2478/s13386-011-0030-9 https://doi.org/10.2478/s13386-011-0030-9 https://doi.org/10.1111/j.1475-4754.1999.tb00987.x introduction study area and sampling methods results and discussion luminescence properties osl quartz ages relationship of fluvial activity and deglaciation history conclusions acknowledgements references assessment of runoff and drainage conditions in a north banat journal of environmental geography 12 (3–4), 13–19. doi: 10.2478/jengeo-2019-0008 issn 2060-467x assessment of runoff and drainage conditions in a north banat sub-catchment, north-eastern serbia milica vranešević, andrea salvai*, atila bezdan, radoš zemunac university of novi sad, faculty of agriculture, department of water management, trg dositeja obradovića 8, 21000 novi sad, serbia *corresponding author, e-mail: andrea.salvai@polj.uns.ac.rs research article, received 30 august 2019, accepted 16 october 2019 abstract the lowland area of the southeastern part of the carpathian basin is exposed to extreme hydrological conditions. the monitoring and analysis of the excess inland water are necessary in order to understand the scope and direction of the development of this type of flooding. when solving the problem of the drainage of an area and dimensioning drainage systems, one of the most important steps is to calculate the rate of runoff. before calculating the rate of runoff, it is necessary to perform various analysis such as: hydrological, hydrogeological, pedological and land use analysis. the use of empirical formulas by different authors is one of the methods for determining the rate of runoff. these formulas can be of regional character, while some are applicable in different parts of the world. in this paper, the runoff coefficient and rate of runoff were calculated as indicators of the efficiency of the area drainage, employing the formulas by nemet and turazzo. the emphasis was put on the usage of modern tools and databases of soil characteristics while using a "traditional" method to determine rate of runoff. the obtained results demonstrate that the rate of runoff which reflects the current state of the drainage basin is very similar to the rate of runoff used for dimensioning of drainage system. the problem of retaining smaller amounts of water that remains even after the anticipated drainage deadlines can be solved with the regular maintenance of amelioration canals and additional ameliorative measures. keywords: galacka sub-catchment, drainage, runoff coefficient, gis introduction the lowland area of the southeastern part of the carpathian basin is exposed to extreme hydrological conditions, therefore the monitoring of the water regime is of great importance on the catchments of this region (právetz et al., 2015). when it comes to excess water, the two most common forms of occurrence are the vertical type, which occurs as a result of the increase in the groundwater level and horizontal type, which is created by the accumulation of water in the lowest areas. horizontal type occurs due to difficulty in infiltration and onflow and often is the result of an inadequate application of agrotechnical measures, which lead to degradation of the soil structure, i.e. its compaction (barta, 2003). monitoring and analysis of such phenomena are necessary in order to understand the volume and direction of the spreading of this type of flooding and mitigate the consequences for agricultural production (van leeuwen et al., 2017). the vojvodina province, the northern part of the republic of serbia, was a wetland area in the past, where after extensive hydro-meliorative works, conditions were created for the development of agricultural production. construction of riverbanks along large rivers, as a form of protection from high waters and construction of drainage canals as a form of protection from inland waters, water regime regulation is achieved. by the construction of the danube-tisza-danube hydro system, drainage of about one million hectares of land in vojvodina has been enabled. thus vojvodina became the main production region in the republic of serbia (kolaković and trajković, 2006). from the roman era, the drainage of lowland areas was done by the construction of open canals or different forms of subsurface drainage, which would provide an adequate water regime for the needs of agriculture. however, mechanization of agriculture, abandonment or change the purpose and land use leads to the dysfunctionality of drainage systems (calsamiglia et al., 2018). in addition, the inadequate function of the system can be the result of climate and hydrological changes that are present in a particular area. therefore, it is justifiable to periodically analyze the efficiency of drainage systems, which could determine the possible causes of their difficulty in functioning. during the solving of the problem of drainage of some area and dimensioning drainage systems, one of the most important steps is calculating the rate of runoff. previously, it is necessary to carry out various analysis, such as hydrological, hydrogeological, pedological and land use analysis. rate of runoff by its size defines the need for the drainage of some area, and it is directly related to the investments necessary for the construction of such systems (avakumović, 2005; kolaković and trajković, 2006). the use of empirical formulas of different authors is one of the methods for determining the 14 vranešević et al. 2019 / journal of environmental geography 12 (3–4), 13–19. rate of runoff. these formulas can be of a regional character, while some are applicable in different parts of the world. however, the final choice of the method depends on the availability of input data (kang et al., 2013). in this paper, using a series of empirical formulas, which were given in the 1965 main project of the drainage of the kikinda canal catchment (galacka sub-catchment), the calculation of the runoff coefficient and the rate of runoff was performed as an indicator of the drainage efficiency of the area. the focus is on combining modern tools and databases on soil characteristics and land use with a "traditional" method for determining the rate of runoff. the obtained results should indicate whether this drainage system adequately performs its function in the current hydrological and agroecological conditions. study area the north banat once represented the flooding area of the unregulated tisza river and the delta of moriš river. after regulating the mentioned rivers and their tributaries, as well as the construction of riverbanks along river streams, there was a need for inland waters drainage. the kikinda canal is the northernmost canal of the danube-tiszadanube hydro-system, and its catchment is divided into 24 subsystems. drainage is carried out by gravity in 20 subsystems, at total area of 418.52 km2, while in combination with gravity and pumping stations, excess water is discharged from 4 subsystems, at total area of 432.40 km2 (pantelić, 1965). the land reclamation works in the subject area start from the moment of regulation of the river tisza and its tributaries till the present day. the galacka sub-catchment covers an area of 32.74 km2. the total length of the canal network is 67.8 km. the water from this system is drained by gravity or by pumping station, depending on the water level in the recipient the kikinda canal. this sub-catchment also includes an area of 4.42 km2 of lowland along the kikinda canal, northern from the recipient. this area is drained by a peripheral canal, which is 10.5 km long. the position of the galacka sub-catchment is shown in figure 1. from the pedological point of view, the types of soil occurring on the kikinda canal catchment can be divided into three groups: zonal soils formed under the dominant influence of the climate, intrazonal soils formed predominantly under the influence of relief and basic rock mass, as well as genetically undeveloped and poorly developed soils (pantelić, 1965). the first group includes chernozem with all its varieties. the second group includes marsh soil and its varieties, while the third group includes alluvial soils and sands. the geological base of these soils are the loess and the hydrological formations of the tisza and moriš rivers, which occur on the fractions of sand, gravel and clay. the loess is mainly wetland origin, made under the influence of winds and sedimentation in the water. its characteristic is that it has a low permeability power and contains a higher percentage of clay particles, which is the main difference from the typical loess. at the territory of northern banat, there is a series of wells in which the groundwater level ranges from 1.5 to 4.0 m below the terrain. therefore, it can be concluded that the influence of groundwater on the rate of runoff is insignificant (pantelić, 1965). the climate of this area is fig. 1 the position of the galacka sub-catchment vranešević et al. 2019 / journal of environmental geography 12 (1–2), 13–19. 15 moderately continental, with a mean annual precipitation of about 560 mm for the observed period 1971-2010. the area is of a very rural nature, where almost 70% of the area is represented by agricultural production. material and methods the vegetation period rainfall analysis showed that the precipitation in terms of its duration, intensity and uniformity was most conspicuous in may. in april and september, precipitations are by its intensity and duration insignificant. in june, july and august they are higher than the precipitations in may, but also short and uneven (characteristic rainstorms). for these reasons, the rainfalls in may are taken as the most appropriate for estimating the rate of runoff (pantelić, 1965). by using the empirical formulas of various authors, obtained from studies carried out in different parts of the world, it is possible to calculate the rate of runoff. in this paper, empirical formulas which were applied in the main project of the drainage of the kikinda canal catchment (galacka sub-catchment) from 1965, were used. in order to determine the efficiency of the drainage of the subject area, the runoff coefficient and rate of runoff are calculated. during the calculation, contemporary databases on pedological soil characteristics (benka and salvai, 2006) and type of soil cover (corine land cover, 2012) were used. different types of land cover are an important factor in modeling surface runoff (právetz et al., 2015). the subject of this paper is the functional check of this drainage system in current conditions, taking into account that it was built more than half a century ago. water from the galacka sub-catchment is drained by gravity or pumping station, depending on the water level in the recipient, the kikinda canal. drainage is done by gravity when the water level in the kikinda canal is below 75.36 m. at water levels in the kikinda canal lower than mentioned, drainage is done through the gravity discharges, and they are 2.0 m3 s-1 capacity. when the water level is higher than mentioned level, drainage is carried out by the pumping station "galacka", using centrifugal pumps with a capacity of 2.0 m3 s-1 (two pumping units, capacity 1.0 m3 s-1). the pump station is located at km 9+516 on the right bank of kikinda canal. for the calculation of the runoff coefficient and the rate of runoff in the main drainage project (pantelić, 1965), the formulas given by the authors nemet and turazzo were used. this method was used in the middle of the last century, mainly for drainage system designing in the area of vojvodina (northern part of serbia) and hungary. the following are the steps used in analysis of this drainage system. the following formula is used for the calculation of the mean rate of runoff: τt hα 0.1157=qs    (eq. 1) where are: qs mean rate of runoff (l s -1 ha-1), α runoff coefficient, h relevant rainfall (mm), t duration of the relevant rainfall (days), τ time of concentration (days). if the previous relation is multiplied by the coefficient that represents the ratio of the maximum and intermediate flows, and which for the hungarian conditions is 1.7 (applicable for the territory of vojvodina), the maximum rate of runoff is obtained qmax (l s-1 ha-1): 1.7 τt hα 0.1157=q max     (eq. 2) when determining the runoff coefficient, it is necessary to take into consideration the drainage characteristics of the soil, the terrain slope, the way of soil cultivating, as well as soil cover type. in the main drainage project (pantelić 1965), it is stated that in the study "amounts of inland waters" by dr j. bogardi, the change in the runoff coefficient by months was given in function of: (1) terrain slope (α1); (2) soil permeability (α2); (3) vegetation cover (α3). the values of these partial runoff coefficients are given in tables 1, 2 and 3. the total runoff coefficient is obtained by summing of these three factors: 321 αααα  (eq. 3) table 1 partial runoff coefficient in the function of terrain slope (α1) terrain slope coefficient α1 >35 % 0.22 – 0.25 – 0.30 11 – 35 % 0.12 – 0.18 – 0.20 3.5 – 11 % 0.06 – 0.08 – 0.10 <3.5 % 0.01 – 0.03 – 0.05 table 2 partial runoff coefficient in the function of soil permeability (α2) soil permeability coefficient α2 very impermeable soil 0.22 – 0.26 – 0.30 moderate impermeable soil 0.12 – 0.16 – 0.20 permeable soil 0.06 – 0.08 – 0.10 very permeable soil 0.03 – 0.04 – 0.05 table 3 partial runoff coefficient in the function of vegetation cover (α3) land cover coefficient α3 non-covered soil 0.22 – 0.26 – 0.30 marshes and pastures 0.17 – 0.21 – 0.25 cultivated soil 0.07 – 0.11 – 0.15 forests and soils of weak structure (sands) 0.03 – 0.04 – 0.05 for the purpose of determining the partial coefficient α2, gis pedological map of vojvodina was used (benka and salvai, 2006). coefficient α2 is obtained by calculating the percentage of different soil types at the subject area and classification according to their drainage 16 vranešević et al. 2019 / journal of environmental geography 12 (3–4), 13–19. characteristics. the soils are classified into five drainage classes based on the average limit values of their water constants and the main chemical parameters (miljković, 2005): (1) drainage class i soil that is naturally very poorly drained, indicating a high risk of excess inland water; (2) drainage class ii soil that is naturally poorly drained, indicating a medium risk of excess inland water; (3) drainage class iii soil that is naturally somewhat poorly drained, indicating a moderate risk of excess inland water; (4) drainage class iv soils of lighter texture which are naturally moderately well drained, indicating a low risk of excess inland water; (5) drainage class v soils of light texture which are naturally well drained, indicating no risk of excess inland water as well as no necessity for drainage. the values of coefficient α3 have been determined using the corine land cover 2012 (eea, 2012) map, which contains data on land cover and attributed areas. gis tools have been implemented in the analysis of the representation of different types of soil and their land cover, as well as the creation of maps presented in this paper. determining the height of relevant rainfall, which is especially used in the prediction of floods with deterministic methods, must be based on the duration of high-intensity rainfall (storm precipitation) or the time of concentration, both for a specific location and a wide area (gericke and plessis, 2011). the time of concentration (τ) is a key temporal parameter of basin response, necessary for the prediction of the maximum volume of runoff (perdikaris et al., 2018). time of concentration (τ) is the time required for runoff traveling from the hydraulically most distant point in the drainage basin to the outlet, and in the project (pantelić, 1965) it is determined with the venturi formula, where it is expressed in the function of the catchment area: f0.315=τ  (eq. 4) where f is catchment area in km2. according to pantelić (1965) rainfall during the month of may was used in the calculation, and with the montanari climatic formula which is individually performed for each analyzed area, relevant precipitation levels were obtained using the following formula: n ta=h  (eq. 5) where are: h – relevant rainfall levels (mm), a and n – variables that depend on the hydrological characteristics of the analyzed area, while t represents the duration of precipitation (days). according to nemet, the duration of relevant rainfall (t) can be determined on the basis of the montanari formula and time of concentration (τ): τ n-1 n =t  (eq. 6) in the main project as stated by pantelić (1965), the duration of relevant rainfall is adopted based on the analysis of the rainfall table in duration t and runoff in duration τ. three cases are characteristic: (1) duration of rainfall is equal to the duration of runoff (t=τ); (2) duration of rainfall is greater than the duration of runoff (t˃τ); (3) duration of rainfall is less than the duration of runoff (t˂τ). in the event that the duration of runoff is less than three days, the duration of relevant rainfall is determined as three days. in the case that the duration of runoff is greater than three days, the duration of relevant rainfall is established to be the same as the duration of runoff. pantelić (1965) maintains that after analysing consecutive daily precipitation levels, t=3 days was for economic reasons adopted as the duration of relevant rainfall. the value of relevant rainfall of 3 days was applied during the calculation of the rate of runoff. results and discussion calculation of the runoff coefficient employing the empirical formulas by nemet and turazzo, the runoff coefficient and rate of runoff have been determined based on current conditions of the drainage system. in order to reach the most precise runoff coefficient it is necessary to meticulously determine the partial runoff coefficients which are given in the function of terrain slope (α1), soil permeability (α2) and vegetation cover (α3). since it is a markedly lowland area, in order to determine the runoff coefficient in the function of terrain slope (α1), the slope of the main canal was used, which steers all water from the analyzed area to the “galacka” pumping station and has an average slope of 0.005%. based on the aforementioned, a minimal value of α1=0.01 was adopted from table 1. table 4 represents the estimation of the complex coefficient value α2, which was obtained based on the soil type represented in the subject area, as well as their drainage characteristics. to calculate the coefficient in the function of soil permeability (α2), the percentage share of different soil types was used and values from table 2 were assigned. the coefficient value in the function of soil permeability which is applied to the entire drainage basin is α2=0.21. the drainage classes of the soils in the subject area are represented in figure 2. from the analysis of the corine land cover 2012 database, which provides soil use and land cover characteristics, a partial coefficient in the function of vegetation cover (α3) was obtained, with the results displayed in table 5. non-irrigated arable land was most represented in the subject area with 62.55%, while natural grasslands were the second most represented with 26.45%. according to the representation of soil types as well as data from table 3, the value of the coefficient in the function of vegetation cover valid for the entire drainage basin was determined to be α3=0.14. figure 3 shows the proportion of soils of different land use and type of land cover. vranešević et al. 2019 / journal of environmental geography 12 (1–2), 13–19. 17 table 4 estimating the partial runoff coefficient in the function of soil permeability (α2) soil type percentage (%) drainage class α2 complex coefficient value α2 alluvial waterlogged soil 8.76 ii 0.16 0.01401 carbonate marsh black soil 4.58 ii 0.16 0.00734 brackish carbonate marsh black soil 1.83 i 0.26 0.00476 marsh black soil without carbonate 33.22 i 0.26 0.08636 partly brackish marsh black soil without carbonate 1.38 i 0.26 0.00358 chernozem on sandy loess 0.25 v 0.03 0.00001 carbonate chernozem (micellar) on a loess terrace 16.38 v 0.03 0.00492 solonetz 25.28 i 0.26 0.06573 solonchak-solonetz 8.32 i 0.26 0.02163 σ= 100 0.20834 fig.2 drainage classes of soil of the galacka sub-catchment table 5 estimating the partial runoff coefficient in the function of vegetation cover (α3) area description percentage (%) α3 complex value of coefficient α3 continuous urban fabric 0.01 0.30 0.00003 non-irrigated arable land 62.55 0.11 0.06881 pastures 6.11 0.21 0.01282 complex cultivation patterns 0.89 0.11 0.00098 predominantly agricultural land with larger areas of natural vegetation 3.43 0.11 0.00377 natural grasslands 26.45 0.21 0.05554 inland marshes 0.42 0 0.00000 mineral extraction sites 0.14 0.3 0.00043 σ= 100 0.14238 18 vranešević et al. 2019 / journal of environmental geography 12 (3–4), 13–19. implementing the formula (3), the total runoff coefficient of the subject area was assessed as α=0.36. the runoff coefficient value calculated for the recent period was slightly greater than the one calculated in the main project. calculation of the rate of runoff the time of concentration (τ) for a particular drainage basin from its most distant point to the outlet is determined with the venturi formula (4) in which the duration of runoff is indicated in the function of the catchment area, with the calculated value being τ=1.8 days. it is a fact that the duration of the return period takes on an economic character, therefore a return period of 10 years is used in hydromeliorative application during the dimensioning of drainage systems (belić et al. 1995). rainfall in a more recent period (1971-2010) was used to calculate the rate of runoff. for that purpose, maximal three-day rainfall in the month of may was used, which occurs once in ten years and amounts to h=54.7 mm. using the formula (2) the maximum rate of runoff was determined to be qmax=0.8 l s -1 ha-1. table 6 displays the comparative results obtained in the 1965 main project of the drainage of the kikinda canal, galacka sub-catchment along with the results obtained for the recent period. considering that the rate of runoff adopted in the main project amounts to qmax=0.60 l s-1 ha-1, while the rate of runoff for the recent period is qmax=0.80 l s -1 ha-1, we may conclude that they are quite similar. table 6 comparative overview of values from the project and new values obtained parameter values from the project (pantelić, 1965) new values unit α1 0.01 0.01 α2 0.18 0.21 α3 0.11 0.14 α 0.30 0.36 t 3.00 3.00 days h 55.4 54.7 mm qmax 0.60 0.80 l s-1 ha-1 conclusion with extensive construction carried out on the drainage canal in the middle of the previous century, the soil on the territory of vojvodina has been transformed from a swamp and marsh area to a soil suitable for agricultural production. the construction of the kikinda canal has allowed the drainage of excess water from substantial surfaces of the analyzed area in banat. the galacka drainage sub-catchment analyzed in the paper belongs to the system of the kikinda canal and the efficacy of its performance has been reviewed. the biggest differences between the values obtained in the main project and those of the analyzed period are fig. 3 corine land cover 2012 map purpose and characteristics of land cover of galacka sub-catchment vranešević et al. 2019 / journal of environmental geography 12 (1–2), 13–19. 19 in regard to the size of the runoff coefficient. sufficient pedological research did not exist at the time of the project, thus leading to different values of analyzed soil permeability in the more recent study. the coefficient value in the function of soil permeability amounts to 0.18 in the main project, while the analysis of more detailed surfaces resulted in a value of 0.21. the utilization of the corine land cover 2012 database resulted in a partial coefficient in the function of vegetation cover (α3) for the recent period amounting to 0.14 while that value was 0.11 in the main project. the rate of runoff which reflects the current state of the drainage basin (qmax=0.80 l s -1 ha-1) is slightly larger than the rate of runoff obtained in the main project (qmax=0.60 l s -1 ha-1). we may conclude that the constructed system is of satisfactory capacity. the results obtained in this paper are in accordance with the research conducted by bezdan et al. (2018) on a drainage basin of similar characteristics in another part of vojvodina (bačka). according to information received by experts in charge of system maintenance, in the previous period there were no major issues related to drainage of excess water. the problem of retaining smaller amounts of water that remains even after the anticipated drainage deadlines can be solved with the regular maintenance of amelioration canals and the employment of additional ameliorative measures. onerous water drainage usually occurs on soil of "heavier" mechanical structure, and in such cases, it is recommended to use horizontal pipe drainage or biodrainage (vranešević et al., 2017). based on the obtained results, we can expect adequate performance of the system in place and timely drainage of excess water. it is our recommendation to regularly maintain the system and utilize additional ameliorative measures in order to improve the conditions for agricultural production. acknowledgement this research was supported by the interreg ipa cbc hungary serbia (husrb/1602/11/0057): wateratrisk improvement of drought and excess water monitoring for supporting water management and mitigation of risks related to extreme weather conditions, co-financed by the european union. references avakumović, d. 2005. hydrotechnical melioration drainage. university of belgrade, faculty of civil engineering. belgrade. (in serbian) barta, k. 2013. inland excess water projection based on meteorological and pedological monitoring data on a study area located in the southern part of the great hungarian plain. journal of environmental geography 6 (3–4), 31–37. doi: 10.2478/jengeo-2013-0004 belić, s., conić, j., škorić, m., stojšić, m., šević, đ., stojiljković, d., zdravić, m., nešković-zdravić, v. 1995. land protection from excessive inland waters drainage. in: belić, s. (ed.) monography of hydrotechnical melioration in vojvodina. institute for water management. novi sad. (in serbian) benka, p., salvai, a. 2006. gis soil maps of vojvodina for integrated water resources management. conference on water observation and information system for decision support balwois. section 8: information systems, cd of proceedings. ohrid rep. of macedonia. bezdan, a., zemunac, r., vranešević, m., salvai, a. 2018. calculation of the runoff coefficient and rate of runoff of the čurug-žabalj catchment. annals of agronomy 42 (2), 21-31. (in serbian) calsamiglia, a., garcía-comendador, j., fortesa, j., lópez-tarazón, j.a., crema, s., cavalli, m., calvo-cases, a., estrany, j. 2018. effects of agricultural drainage systems on sediment connectivity in a small mediterranean lowland catchment. geomorphology 318, 162–171. doi: 10.1016/j.geomorph.2018.06.011 eea, 2012. corine land cover 2012. european environmental agency https://www.eea.europa.eu/data-andmaps/data/external/corine-land-cover-2012. gericke, o.j., du plessis, j.a. 2011. evaluation of critical storm duration rainfall estimates used in flood hydrology in south africa. water sa. 37 (4), 453–470. doi: 10.4314/wsa.v37i4.4 hidmet, 1971-2010. hydrological yearbooks. vol 1. climatological data. republic hydrometeorological service of serbia, belgrade. http://www.hidmet.gov.rs/ kang, m.s., goo, j.h., song, i., chun, j.a., her, y.g., hwang, s.w., park, s.w. 2013. estimating design floods based on the critical storm duration for small watersheds. journal of hydroenvironment research 7, 209–218. doi: 10.1016/j.jher.2013.01.003 kolaković, s., trajković s. 2006. hydrotechnical melioration drainage. faculty of technical sciences, university of novi sad, faculty of civil engineering and architecture, university of niš. (in serbian) miljković, n. 2005. meliorative pedology. faculty of agriculture, wmc vode vojvodine. novi sad. 322-325 p. (in serbian) pantelić, p. 1965. drainage of the kikinda canal (main project). hidrozavod: projektni biro direkcije za izgradnju hidrosistema dunav-tisa-dunav. novi sad. (in serbian) perdikaris, j., gharabaghi, b., rudra, r. 2018. reference time of concentration estimation for ungauged catchments. earth science research 7 (2), 58–73. doi: 10.5539/esr.v7n2p58 právetz, t., sipos, g., benyhe, b., blanka, v. 2015. modelling runoff on a small lowland catchment, hungarian great plains. journal of environmental geography 8 (1–2), 49–58. doi: 10.1515/jengeo-2015-0006 van leeuwen, b., tobak, z., kovács, f., sipos, g. 2017. towards a continuous inland excess water flood monitoring system based on remote sensing data. journal of environmental geography 10 (3–4), 9–15. doi: 10.1515/jengeo-2017-0008 vranešević, m., belić, s., kolaković, s., kadović, s., bezdan, a. 2017. estimating suitability of localities for biotechnical measures on drainage system application in vojvodina. irrigation and drainage 66, 129–140. doi: /10.1002/ird.2024 ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! ../zemunac/radovi%20u%20ä�asopisima/journal%20of%20environmental%20geography/s0169555x18302423.htm#! introduction study area material and methods results and discussion calculation of the runoff coefficient calculation of the rate of runoff conclusion acknowledgement references journal of environmental geography journal of environmental geography 7 (3–4), 13–19. doi: 10.2478/jengeo-2014-0008 issn: 2060-467x mapping freshwater carbonate deposits by using ground-penetrating radar at lake kolon, hungary eszter pécsi 1* , orsolya katona 1 , károly barta 1 , györgy sipos 1 , csaba biró 2 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 directorate of kiskunság national park, liszt f. u. 19, h-6000 kecskemét, hungary *corresponding author, e-mail: pecsi.eszter18@gmail.com research article, received 02 march 2014, accepted 13 may 2014 abstract freshwater carbonate deposit, as a special phenomenon in the danube-tisza interfluve, located in the centre of hungary, is a significant geological heritage in the carpathian basin. at present there is not any applicable method to investigate the presence of carbonate layers in an undisturbed way, as neither vegetation nor morphological characteristics indicate unambiguously these formations. ground-penetrating radar technology is widely used in various earth science related researc hes, and the number of applications is steadily increasing. the aim of the study was to determine the spatial extension of freshwater limestone using geophysical methods near lake kolon, hungary. the lake, which is now a protected wetland area with opened water surfaces, was formed in the paleo -channel of the river danube. measurements were performed with the help of ground-penetrating radar, the results were calibrated by high spatial resolution drillings. investigations have been made since 2012, and freshwater limestone was detected at seve ral locations determining the more exact extension of the formation. ground-penetrating radar proved to be an appropriate method to detect the compact and fragmented freshwater limestone layers in such an environment. however, based on the results the method can be best applied under dry soil or sediment conditions while the uncertainty of the results increases significantly as a matter of higher soil moisture. further control measurements are necessary verified by several drillings in order to give an exact method to determine freshwater limestone. keywords: freshwater limestone, ground-penetrating radar, lake kolon, drilling introduction freshwater limestone is a significant but unique geological formation (philip, 1987) in the arid and semiarid areas around the world. it can be found in california, where besides geological research it is also used for building purposes (goodfriend and stipp, 1983). in australia a vast amount of freshwater limestone has been formed, here wine is being cultivated on the surface (johns, 1963). similar formations have evolved in iran and in inner-anatolia (thomas et al., 1981; gail et al., 2014). in hungary it has been mined since the arpad era, it has been used for building purposes, which is being neglected nowadays. the reason may be the artificial improvement of building material, as well as the delivery made easier with the improvement of technology and logistics. tálasi (1946) pointed out the usage of freshwater limestone during his ethnograp hical research in danube-tisza interfluve. he emphasized in his study that freshwater limestone is being mined and made use of the same way as two centuries before. since the 1970’s environment protection has been given more emphasis, and the unique nature of freshwater limestone has been largely recognized as well. as a result, more and more people think that it is essential to gain thorough knowledge of this geolog ical formation, because, it being a unique formation, it is part of our geographical heritage, and by studying it, we are able to understand the details of its fo rmation process (sümegi et al., 2013). despite the fact that the appearance of freshwater limestone is known in danube-tisza interfluve, there is not any applicable method which would be able to prove its presence from either ecological or morphological characteristics. the aim of this research is to border both the solid, compact and scattered freshwater limestone with help of ground-penetrating radar on two study areas. it was tried to determine the presence and deepness of freshwater limestone both with boreholes and with ground-penetrating radar. the results received by the ground-penetrating radar were calibrated with the drilling data, so it was able to border the extension of freshwater limestone on the study areas. in order to find out the spatial extension of freshwater limestone, measurements with the help of ground-penetrating radar have previously taken place in turkey (selma, 2008). the main aim of this study was to determine the thickness of freshwater limestone with ground-penetrating radar on turkish study areas, as well as to map the caves and joints in the limestone. 14 pécsi et al. (2014) during the research several fissures and caves were located, and an accurate estimate was given about the deepness of freshwater dolomite. further ground-penetrating radar research took place in denmark, but not on freshwater dolomite (nielsen et al., 2004). during the measurements the geometrical characteristics of limestone structure were mapped. that way it is possible to forecast the possible behaviour of limestone layers, in case of seismic events. as a result, an important evaluation came to existence about contingencies concerning reservoirs on limestone surfaces. a similar study took place in germany; it’s about to map limestone’s structure (asprion et al., 2000). the measurements proved that the ground-penetrating radar is particularly suitable for analyzing limestone, defining its geomorphological structure, and it provides help in defining the individual facies in the limestone structure. the aim of this study is to prove that groundpenetrating radar is suitable to determine where this geological formation can be found and regardless of whether the freshwater limestone is compact or fragmented. dolomite formation in the danube-tisza interfluve the process of dolomite formation is probably most thoroughly described by morrow (1982). the fo rmation process is the thermodynamical transformation of dolomite, lasting from calcite to dolomite (morrow, 1982; jenei, 2007). it is pointed out that the two main influencing factors are the velocity of crystallization and the proportion of ca/mg. this lattest one can help the process if it is higher than 1. carbonates in the danube-tisza interfluve have been given attention since the 1930’s (faragó, 1938). formations and sedimentary rocks from the ice age and from the holocene have been studied in the area and as part of these geological researches freshwater limestone has also been examined (miháltz, 1938, miháltz and faragó, 1945). besides the formation process the spatial extension of this phenomenon has also been pointed out. it was stated that carbonate rocks had been formed in loess and in small patterns near blown sand forms and in lakes’ deeper carbonate sludge layers (mucsi, 1963). it was also pointed out that the water level of several lakes is found lower than the groundwater level of the neighbouring territ ories, so the groundwater with different solute minerals inside is leaking towards the lakes helping the ca rbonate accumulation (miháltz and mucsi, 1964). later geochemical, paleontological and sed imentological research was made on this formation (molnár and kuti, 1978a). during the research the evolution conditions of freshwater limestone have been defined, the environmental conditions de termining the evolution of freshwater limestone have been presented, the time interval, during which under the given environmental conditions this significant ge ological formation evolved, was restricted. besides, they proved that during the evolution process evaporation is of immense importance, as the solute minerals can move closer to the surface of the soil (molnár and kuti, 1978b). they stated that sodic lakes include a vast amount of calcium, so the conditions are given to the formation of freshwater limestone. via collected water samples it has been established that the proportion of co3/ca is always higher than one, therefore the formation of dolomite can take place in the investigated area (molnár and jenei, 2006). several further publications can be found about pollen analytical, malacological, and sedimentological r esearches about the kiskunság (sümegi et al., 1991; molnár and botz 1996; sümegi et al., 2005; jenei et al., 2007; sümegi et al., 2011). these publications also mention several aspects of freshwater limestone around lake kolon. during these researches the picture about environmental conditions and their changes has been clarified as well. at the end of the ice age, a significant climate change took place, which induced several further changes, and thus enabled the formation of freshwater limestone in kiskunság. the local accumulation of blown sand started at this period as well, this is today’s be drock level in kiskunság (sümegi et al., 2013). eolic forms like hummocks, and parabolic dunes evolved in this period. besides, they stated that the accumulation of chemical components necessary for the formation on freshwater limestone, like ca and mg, took place in sedimentary basins, and hollows between hills (iványosi, 2013). the accumulation of carbonate sludge is very typical in the soils of the danubetisza interfluve and several carbonate resources are worth mentioning in this area (fügedi et al., 2008 ; molnár, 1980). one of them is the organic resource originated from fossil remains like snails and shells, which plays a significant part during formation. a nother carbonate resource determining process is the changing ground water level and the capillary water lifting that is also an influential factor. in warm periods, the salts in the groundwater approach the su rface with the steaming water, then they are evap orated. the rock hardening takes place in this period, along with the cementation of the accumulated carbonate sludge, which in this case, is a fast process, i n which the periodical water cover is a determining factor. if there is a permanent water cover, then there is no possibility to dry surface and subsurface layers, so compact freshwater limestone is unable to be formed, only uncompacted carbonate sludge remains in the area (sümegi et al., 2013). study area lake kolon is located in the middle of hungary, in the danube-tisza interfluve (fig.1); it is the greatest and most significant freshwater swamp of the regio n. it is situated in north-western direction from the settlement izsák, it is approximately 7 kilometers long and it is found 5-6 kilometers eastwards from the western border of kiskunság sand back. mapping freshwater carbonate deposits by using ground-penetrating radar … 15 the lake and its environment are found in an e xcessively fragmented area. the area is divided into three geomorphological units: bikatorok hill and its environment (w from the lake) were formed by aeolian processes, elder fluvial sediments are buried by sand. the highest point of this area is revecke hill with height 120 m. lake kolon and its near environment are in the ancient danube riverbed. its shape’s direction is north-south, the bed is gradually rising from west to the east. sandy loess back near izsák is a little bit higher surface formed by wind but with lower relief than bikatorok. lake kolon is part of the kiskunság national park and the marshlands and surrounding areas are strictly protected. the extension of the national park exceeds 48.000 hectares, the lake itself is 2962 hectares from it. two sample sites have been appointed in the lake basin. the northern one so called “tókás” (fig. 1.) is located in the direct neighbourhood of izsák, in the south-western direction, the north-eastern shore of lake kolon; as a natural meadow. the height difference between the highest and lowest points is 1.2 meter. the second study area is situated on the southern part of lake kolon, near the ash-oak bog forest called “közös-erdő”. the study area is located on its margin as a swamp meadow with variable hydrological and ecological conditions from permanent water cover until steppe-like grasslands. materials and methods in order to map the freshwater limestone on the sample sites, first hand drill and the pürkhauer sticking rod was applied. when it has reached the freshwater limestone, its deepness was measured from the surface, as well as its appearance (hooked, compact, etc.). guessing from the occurrence of freshwater limestone based on its formation process, it was mapped with denser drilling network, but at the same time there were several control points on higher surfaces as well; so altogether on the northern area was made more than 100, while at gulya-kút about 140 boreholes. the digital elevation model (dem) of the study areas was prepared in arcgis. with the help of dems it was possible to locate the territories more effectively, where freshwater limestone might have been formed with more probability. it can be found in lower relief, closed hollows, and under their concave slopes. that way it is possible to make impoundment on both sample sites, with combining drilling data with the groundpenetrating radar results. in the sections between the point-like drillings it’s possible to map freshwater limestone with the help of ground-penetrating radar. ground-penetrating radar consists of a transmitter, a receiver and a control unit (katona et al., 2013). its operation is based on the transmitter emitting electromagnetic impulses, which has strong reflection from even surfaces and depending on electromagnetic characteristic of the investigated surface diffraction can occur (jol, 2009). electrical permittivity, magnetic permeability and electrical con fig. 1 location of lake kolon in danube-tisza interfluve and the two sample sites 16 pécsi et al. (2014) ductivity determine the reflection of electromagnetic waves from objects in the investigated material. the reflected wave is being received by the receiver, after the registration the data, stored in digital form (cardimona et al., 2000). because of the measurement area of the ground-penetrating radar, it is not possible to give the locality with absolute precision, because the ground-penetrating radar transmits electromagnetic impulses in the subsurface layers forwards and backwards in 60° angle, sideward in 90° (casa et al., 2000). the differences in the measured material can be determined based on the reflected signal amplitudes, frequency and phase. the measurements were completed with 400 mhz antenna, in central frequency. on the northern shore of lake kolon altogether 7 ground-penetrating radar cross sections were registered and 6 ones on the southern sample site. ground-penetrating radar segments were planned mainly through points, where during the previous drillings freshwater limestone has been found. recording these points has been important because of the calibration with ground-penetrating radar. first static correction was applied on the registered segments. after that, band pass filter was applied to remove noise. migration steps were used to determine the velocity of electromagnetic wave in the different part of the investigation area. by analyzing the magnitude and frequency, it was possible to allocate the presence of freshwater limestone on the ground-penetrating radar map. ground-penetrating radar was used for the determination of limestone amounts on the previously allocated points based on samples taken from the soil. altogether 5 segments and 25 soil samples have been collected. the carbonate content in the samples was determined with scheibler calcimeter. in light of the results it is possible to border the territories where there is a high carbonate capacity in the soil. that way the ground-penetrating radar measurements can be calibrated with pedological properties, because both soil conditions and its physical characteristics influence the results of ground-penetrating radar measurements. results and discussion at “tókás” freshwater limestone was found in 45 cases between 35 and 100 cm deep in the soil, while at 60 boreholes the presence of the formation is not detected. besides at “gulya-kút” freshwater limestone was found at 64 points, between 60 and 120 cm deep; at 55 points it was not detected the presence of fres hwater limestone with drilling. where its presence was not obvious, in these cases it is due to the soil being full of pieces of limestone and this condition inflicts same received signal like dolomite on the ground penetrating radar map. these cases occurred 5 times on the north, and 10 times on the south. based on the drillings, one can state that freshwater dolomite is not a continuous strata, but a fragmented phenomenon on the study areas (fig. 2). in order to eliminate the uncertainty, ground penetrating radar measurements were calibrated with drilling results. on the deeper reliefs the drill ing results unanimously proved, how the freshwater limestone might have been formed; this has been suppor ted by the ground-penetrating radar research, according to which a more dominant signal can be detected on these points. here the signal is stronger on the groundpenetrating radar map, but probably not because of the fig. 2 ideal case: detection of freshwater limestone’s presence based on the electromagnetic wave magnitude left: compact limestone, right: fragmented limestone (2012) mapping freshwater carbonate deposits by using ground-penetrating radar … 17 physical characteristics caused by the high amount of limestone in the soil, but because of the presence of freshwater limestone. nevertheless, on points, where based on the drillings, no dolomite can be found, the ground-penetrating radar still measured under surface discrepancies, this is due to the fragmented nature of the formation, along with the aforementioned high amount of carbonate, which on the northern sample ground collected from the given deepness, is 28,8%, while on the southern sample grounds 53%. previously, in autumn 2012 ground-penetrating radar research was conducted. this year it was examined after a long dry period, with deep groundwater. at this time it was possible to unequivocally determine the compact and fragmented limestone, it was not necessary to take into consideration the disturbing effect of high carbonate-content of the soil on the ground-penetrating radar maps (fig. 3). a year later measurements were made after a rainfall period with high groundwater (autumn 2013). although the high soil moisture content enhances the amplitude of the electromagnetic waves, it causes signal loss. due to the signal loss interpreting the ground-penetrating radar segments proved to be difficult, therefore it wasn’t possible unequivocally to determine the presence of limestone. in the deeper layer, during the set fortifications in the measurements the formations close to the surface are not reflected, so it is not possible to unequivocally border the freshwater limestone (fig. 4). fig. 5 results of the investigation in the northern study area (tókás) fig. 3 calibrated on the basis of drilling data, ground-penetrating radar cross section recorded in dry period. there is fragmented formed limestone between compact layers (marked in black) (2012) fig. 4 a ground-penetrating radar image received after rainfall in october 2013. existence of freshwater limestone is not clear 18 pécsi et al. (2014) fig. 6 results of the investigation in the southern study area (gulya-kút) conclusions ground-penetrating radar can be used to map freshwater limestone. it was established that high soil moisture content is not optimal environment for taking measurements; therefore it is worth taking into co nsideration the given environmental factors. the ele ctromagnetic wave applied by the ground-penetrating radar, due to its characteristics, easily shows freshwater limestone on records on dry soil. the moisture content of the environment largely influences the measurements made by ground-penetrating radar. the moisture content reduces the penetrating deepness, as well as enhances value of the reflected electromagnetic wave’s amplitude. accordingly, although the r eflected electromagnetic wave’s amplitude is higher, it cannot be applied with such soil conditions, due to the quick absorption of the sign. dry weather and deep ground water are preferable when making measurements. therefore, it is advisable to conduct research in early autumn, or in summer, after a long rainfall free period, in order to avoid signal loss. in case of wet, clayey soil the signal loss might be significant . with the help of ground-penetrating radar both compact and fragmented freshwater limestone can be traced, if the measurement took place during a dry period. otherwise the ground-penetrating radar cannot clearly distinguish between freshwater limestone and high carbonated soil because of its characteristics. in this case it is worth combining research data with other methods, in order to specify the final results. it means that ground-penetrating radar can open new perspectives for mapping freshwaters limestone: the former point based mapping can be changed to linear mapping (fig. 5-6) that gives us more adequate and faster method for determining its spatial extension. references asprion, u., aigner, h., aigner, t. 2000. an initial attempt to map carbonate buildups using ground-penetrating radar: an example from the upper jurassic of sw-germany. erlangen (2000) 42, 245–252. cardimona, s., webb, d. j., lippincott, t. 2000. ground penetrating radar. department of geology and geophysics, university of missouri-rolla, rolla, mo., 2–9. casa, a., pinto, v., rivero, l. 2000. fundamentals of ground penetrating radar in enviromental and engineering applications. annali di geofisica, vol. 43, n. 6, december 2000. department of chemistry, petrology, and geologycal prospecting, faculty of geology, univerity of barcelona, spain, 1091–1097. faragó, m. 1938. nagykőrös környékének felszíni képződményei. földtani közlöny 68, 144–167. fügedi, u., pocsai, t., kuti, l., horváth, i., vatai j., 2008. a mészfelhalmozódás földtani okai közép-magyarország talajaiban. agrokémia és talajtan 57/2, 239–260. gail, m. a., carol, b., manuel, d-r., alyssa, m.k., theresa, m.o., rodinell, b. 2014. freshwater limestone in an arid rift basin: a goldilocks effect. journal of sedimentary research 84, 988– 1004. doi: 10.2110/jsr.2014.80 goodfriend, g.a., stipp, j.j. 1983. limestone and the problem of radiocarbon dating of land snail shell carbonate. geology 11, 575–577. iványosi szabó, a. 2013. csólyospálosi földtani feltárás természetvédelmi terület. in: kustár, r., balázs, r. 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(ed) az alföldi tudományos intézet évkönyve 1/1944-45, 1–35. thomas n. t., robert m. o., bruce h. w. 1981. sr/ca and mg/ca ratio sin polygenetic carbonate allochems from a michigan marl lake. geochimica et cosmochimica acta 45, 439-445. doi: 10.1016/0016-7037(81)90252-0 the potential use of osl properties of quartz in investigating fluvial processes on the catchment of river mureş, romania journal of environmental geography 14 (1–2), 58–67. doi: 10.2478/jengeo-2021-0006 issn 2060-467x the potential use of osl properties of quartz in investigating fluvial processes on the catchment of river mureş, romania tamás bartyik1, cristian floca2, elemér pál-molnár1,3, petru urdea2, diaa elsayed hamed4, györgy sipos1* 1geomorphological and geochronological research group, department of geoinformatics, physical and environmental geography, university of szeged, egyetem u. 2-6, 6722 szeged, hungary 2department of geography, west university of timișoara, b-dul. vasile. parvan nr. 4, 300223, timișoara, romania 3department of mineralogy, geochemistry and petrology, university of szeged, egyetem u. 2-6, 6722 szeged, hungary 4national research institute of astronomy and geophysics, el marsad street 1, helwan, cairo 11421, egypt *corresponding author, email: gysipos@geo.u-szeged.hu research article, received 15 march 2021, accepted 23 april 2021 abstract to understand the functioning of fluvial systems it is important to investigate dynamics of sediment transport and the source of sediments. in case of reconstructing past processes these studies must be accompanied by the numerical dating of sediment samples. in this respect optically stimulated luminescence is a widely used technique, by which the time of sediment deposition can be directly dated. recently, in various fluvial environments it has been shown that certain luminescence properties of minerals, and especially that of quartz, can be applied as indicators of fluvial erosion and/or sediment provenance. these properties are residual luminescence (or residual dose) and luminescence sensitivity of quartz grains. however, the values of the parameters above are affected by various factors, the importance of which is under debate. the present study therefore aims to assess these factors along a ~560 km long reach of river mureş (maros) a relatively large river with a compound surface lithology on its catchment. the research focused on the sandy fraction of modern sediments, collected from the main river and from three tributaries alike. this way not only longitudinal downstream changes, but the influence of tributaries could also be studied. based on the data, both investigated parameters show a great variation, which can be attributed to the lithological differences of subcatchments and geomorphological drivers, such as erosional activity and potential number of sedimentary cycles, and human activity. however, relationships are not entirely clear and are influenced by the maximum grain size of the samples investigated, and the recycling of previously laid deposits with different properties. still, when performing detailed dating studies, and tracing sediments from certain parts of the catchment luminescence properties can be a useful tool in the future. keywords: sediment tracing, luminescence sensitivity, fluvial sediments, erosion, river mureş introduction alluvial deposits are made up of a complex mixture of mineral grains originating from several subcatchments of a river usually with different lithology and erosional intensity. in sedimentary basins with complex river system, the reconstruction of fluvial processes often requires the tracing of sediments in order to assess major avulsion events, channel migration, or the variable activity of catchments, governed by climatic or tectonic processes (schumm, 1979). traditionally, sediment tracing is based on geochemical, mineralogical or other physical, such as magnetic properties by which unique fingerprints are aimed to be identified, which can be then attributed to certain parts of the catchment (e.g. fryirs and gore, 2013; walling, 2013; collins et al., 2020). however, sediment tracing also requires the numerical dating of sediments, as the comparison of fingerprint properties is only viable if the age of deposition is known (collins et al., 2020). not just because temporal changes may occur in the activity of catchments, but because the true proportion of sources can be determined if sediments of the same age are investigated (walling, 2013). in this respect, a relatively new method for sediment tracing is the investigation of luminescence properties of sedimentary quartz grains, which can be done parallel to the dating of sediments by the means of optically stimulated luminescence (osl) (gray et al., 2019). osl is based on the fact that certain minerals, such as quartz and feldspars function as natural dosimeters recording total environmental radioactivity in their surroundings since their last exposure to sunlight, i.e. since sediment deposition (aitken, 1998; bøtter-jensen et al., 2003). subsequent to exposure, incident radioactive particles exc ite the semiconductor natural crystals and charges reaching the valence band are trapped at crystal defects (e.g. vacancies, interstitial ions). the longer time passes since deposition, the more charges are trapped, and the higher luminescence intensity can be measured in the laboratory when charges are artificially detrapped mailto:gysipos@geo.u-szeged.hu bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. 59 using light or heat. however, the measured luminescence intensity is depending not only on the age, but also on the charge trapping capacity of the crystals, determined primarily by the number of crystal defects. consequently, the intensity measured in response to unit radioactive dose is termed as luminescence sensitivity (preusser et al., 2009; sawakuchi, 2011; sharma, 2017; gray et al., 2019). as luminescence sensitivity is a sample dependent property, thus it has a unique potential in sediment tracing (gray et al., 2019). this is especially true for quartz, since it can exhibit highly variable sensitivity values, as shown by the study of bartyik et al. (2021). luminescence sensitivity of quartz is primarily determined by the lithology and mineralogy of source rocks. impurities, developing during the crystallization process, are responsible for the primary charge trapping capacity of the lattice and determine the magnitude of luminescence intensity (zheng, 2009; lü and sun, 2011; sawakutchi et al., 2011). as pointed out by previous researches, quartz from metamorphic and igneous rocks usually has low sensitivity compared to those originating from sedimentary rocks (chithambo et al., 2007; guralnik et al., 2015; sawakutchi et al., 2018). a difference was also identified based on the formation temperature of rocks (sawakutchi et al., 2011). thus, crystallization temperatures can be of significant influence on quartz sensitivity (sharma, 2017; sawakutchi et al., 2020). in the meantime, luminescence sensitivity can increase due to geomorphological processes, most likely as a consequence of recurring sedimentary cycles and long transportation distance, meaning repeated sunlight exposure and natural dosing (fitzsimmons, 2011; wintle and adamiec, 2017). for example, the high luminescence sensitivity of australian sedimentary quartz is usually explained by the extensive and the repeated reworking of sediments (pietsch et al., 2008; fitzsimmons et al., 2010; fitzsimmons, 2011). similarly, preusser et al. (2006) claimed that the low luminescence sensitivity of quartz in sediments of new zealand is primarily caused by their short sedimentary history. in another study, for australian river sediments, gliganic et al. (2017) observed an increase in luminescence sensitivity going downstream. however, no such tendency was detected in terms of the amazon river basin (sawakuchi et al., 2018), where differences and downstream change of quartz sensitivity could rather be related to the lithological background of subcatchments (sawakuchi et al., 2012). beside sediment cycling, the mode of sediment transport can also have significant role in determining the natural sensitivity of grains (li and wintle, 1991,1992). though, in her study on austr alian quartz from various depositional environments fitzsimmons (2011) found no systematic sensitivity difference between aeolian and water-lain sediments. the influence of both lithological background and sedimentary prehistory of samples thus proved to be important in the level of luminescence sensitivity. beside sensitivity, other osl properties can also be used to investigate fluvial systems, namely if exposure to sunlight is not of adequate length, residual luminescence signals may be reserved in the crystal lattice (godfrey-smith et al., 1988; tóth et al., 2017; smedley et al., 2019). this often occurs, since turbulence, together with water depth attenuate the intensity of sunlight reaching the grains and thus lead to reduced bleaching (gemmell, 1988; berger, 1990; rendell et al., 1994). although residuals can adversely affect the accuracy of the dating procedure and usually lead to age overestimation, they can also be applied to investigate the sedimentary dynamics and erosional capacity of river channels (fiebig and preusser, 2007; sipos et al., 2016; tóth et al., 2017), as far as high residuals indicate the proximity of the sediment source. as it has been shown above, the osl properties of quartz grains can be influenced by many factors, and the understanding of these factors requires the systematic investigation of river systems. from this point of view, river mureş can be a good choice because sedimentary, igneous and metamorphic rocks are all present on its relatively large drainage basin. additionally, due to the elongated shape of the catchment the role of subcatchments with different surface lithology can be distinguished relatively well on its upper reaches, while along its lower reaches no major tributaries join the river, primarily geomorphological processes should determine the luminescence properties of quartz grains on this section. therefore, the aim of the present research was to investigate the change of some key luminescence properties along an approximately 560 km long section of river mureş in order to see how subcatchments with different surface lithology, and transportation distance, i.e. repeated reworking of sediments, affect residual doses and luminescence sensitivity of quartz grains. the research also enabled the assessment of the applicability of luminescence properties as a sediment tracer in a relatively large river system. study area and sampling river mureş (maros) is the fourth largest waterflow in the carpathian basin. the area of the its catchment is approx. 30 000 km2, the majority of which falls in romania and drains the waters of the transylvanian basin (laczay, 1975). the upstream part of catchment (250x100 km) is rectangular, while the downstream section (200x30 km) starting from deva is elongated (urdea et al., 2012). concerning river morphology and surface lithology, the course of the river can be separated into four major reaches (fig. 1). the uppermost, steepest upland reach from the source of the river till deda is dominated by volcanic rocks (urdea et al., 2012; pál-molnár et al., 2015). the next section from deda to alba iulia is characterized by a significantly lower slope as the river enters the hilly landscape of the transylvanian basin, built up of neogene marine and lacustrine sedimentary rocks (baranyi et al., 2020). the largest tributary of the river, târnava (küküllő) is also situated in this lithological domain. however, on the downstream part of this 60 bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. section tributaries, such as the arieș (aranyos), already introduce to the main river sediments produced in the apuseni mountains with a complex mixture of surface lithology comprised of metamorphic, magmatic/ plutonic, volcanic and sedimentary rocks of various origin (kounov and schmid, 2013; silye, 2015). downstream of alba iulia, the river flows till lip ova along the tectonic line dividing the apuseni mountains and the southern carpathians. in this area, small northern tributaries carry the sediments of the metaliferi (transylvanian ore) mountains, rich in volcanic rocks and ores, to the main river. larger southern tributaries, such as the sebeş (sebes) and strei (sztrigy) transport their sediments mostly from the metamorphic and plutonic rocks of the southern carpathians (bojar et al., 2010; iancu and seghedi, 2017). on the lowland section, downstream o f lipova the mureş has built an extensive alluvial fan, on which it has frequently changed its direction even in the holocene, thus here it reworks its own alluvial deposits (borsy, 1989; kiss et al., 2013). in the present study, a 565 km section between târgu mureş and the confluence to the tisza was studied, along with three of the largest tributaries of the river: arieș, târnava, and strei (fig. 1). to investigate the change in luminescence sensitivity, modern sediment samples with similar geomorphological position were collected from the river channel, usually from side bars, point bars or sand sheets on the river bank (fig. 2a-b). potential sampling points were pre-selected using satellite images taken at low water periods. sampling was carried out at 16 locations along the mureş river, while in the case of tributaries two samples were collected upstream of their confluence at 2-4 rkm and at 8-14 rkm in each case. thus, we sampled a total of 22 locations in the entire study area (fig. 1, table 1). sampling took place during the autumn low water period. at each point, we aimed to collect samples rich in sand. in the case of the samples on the bank of the channel, sample collection was made using a spatula (fig. 2c). in case of river bars, sampling was made using a pvc tubes (fig. 2d). methods laboratory processing of the collected samples followed general laboratory techniques (mauz et al., 2002; sipos et al., 2016). after removing the light exposed outer layer in the dark laboratory the samples were dried. then by sieving the 90-150 μm, 150-220 μm and 220-300 μm fractions of samples were separated by wet sieving. in many cases, however, there was enough quartz for the measurements only by mixing the previously separated fractions (table 1). the carbonate and organic material content of samples were removed by repeated treatment in 10% hcl and 10% h2o2. the quartz fraction was separated by using lst (sodium polylungstanate) heavy liquid. this step was followed by a 50 min 40% hf etching to remove unwanted feldspar residues as well as the external shell of quartz grains. for measuring residual doses purified quartz samples were adhered on ø10 mm stainless steel discs using silicone spray and a 2 mm mask. for sensitivity measurements, ø10 mm diameter stainless steel cups were used, into which a 6 mg of sample was measured with an analytical balance. fig. 1 the surface lithology of the catchment of river mureş and the location of sampling points (based on harta geologică a r. s. românia, sc. 1:200.000, 1967 maps). bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. 61 both residual dose and luminescence sensitivity measurements were performed using a risø tl-da20 luminescence reader. a 90sr/90y βsource was used for irradiation, while an emi et9107 photomultiplier (pmt) with a hoya u-340 filter was used for detecting the luminescence signal. the residual dose, i.e. the equivalent dose of modern samples was determined using the single aliquot regeneration (sar) protocol (wintle and murray, 2006). sensitivity measurements were performed based on the procedures detailed in bartyik et al. (2021). first, 5 aliquots from each sample were bleached by using blue leds to remove the natural signal. then each aliquot received a uniform β-dose of 22 gy. the luminescence response elicited by this dose was measured using the continuous wave osl (cw -osl) technique during which the led power was always the same. background was subtracted using the last 5 s of the decay curve. results were then normalized by the mass of the samples, measured by an analytical scale. this normalized intensity was considered as the "normalized cw-osl sensitivity" of the samples. to examine the lithological background and to delineate the main surface lithological units, 1: 200 000 scale geological maps were used (harta geologică a r. s. românia, 1967). the catchment of the mureş is covered by 15 map sheets, which were georeferenced using esri arcmap. after georeferencing the map sheets, surface lithology was digitized. the proportion of different rock types was determined for the investigated subcatchments and compared to the luminescence sensitivity values obtained. results and discussion residual dose based on the sar measurements, each sample had a low level of natural luminescence, meaning that grains were well bleached (fig. 3a-b). in case of one sample (sample 565 rkm) no curve could be fitted to the plot of laboratory doses and luminescence responses (dose response curve) (fig. 3c-d). in case of the other samples fitting was successful, and obtained residual doses varied between 0.4 and 3.9 gy, however results had a high standard error (table 1). thus, coarse grain paleo fluvial samples subjected to dating in the area can overestimate the true age of deposition by around 0.22.0 ka if a usual 2 gy/ka dose rate is taken (kiss et al., 2014; tóth et al., 2017). comparing these results with the residual values measured nearly 417 km long hungarian section of the danube by tóth et al. (2017), it can be seen that much higher values can be observed in the case of river mureş. in his research the mean residual dose of coarse grain quartz was 0.1±0.01 gy while the maximum value was only 0.56±0.17gy, which cause a negligible overestimation between 60 and 120 y in the area. on the other hand, an overestimation of 1.2 -2.3 ka has already been found for the fine grain samples, which is similar to the mureş coarse grain quartz values. regarding that danube, however, fiebig and preusser (2007) measured very high residual dose (around 6.1 gy) in their research on the vienna section, which were explained by anthropogenic effects. fig. 2 typical sample collection sites include point bars (a) and side bars (b). sampling was performed from the uppermost, thus freshly deposited sediments by spatula (c) or plastic tube (d) for undisturbed samples. 62 bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. if residual doses are analyzed along the longitudinal profile of the river (fig. 4 and table 1) it is obvious that in general, there is a decreasing trend in residual dose values. it is in accordance with the fact that channel sediments should be reworked more times towards downstream, and therefore bleaching by sunlight can be more complete. however, local peaks can be observed, and tributaries also show different values. upstream of the conjunction of river arieș (aranyos) the value of the measured residual dose is 2.07±0.60 gy (sample 491 rkm), and although the quartz grains of arieș sediments have a highly variable residual dose they stay in the same range and seemingly do not affect significantly the values measured downstream of the confluence. the first and largest peak can be seen in case of sample 448 rkm with a value of 3.88±0.79 gy. fig. 3 dose response curves of two samples. sample 225 rkm sample (a, b) showed a typical decay with a low signal, while at 565 rkm (c, d) it can be seen that due to a signal close to 0 s, a line cannot be fitted to the data. fig. 4 residual dose of the tested samples measured by cw-osl technique. bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. 63 the sampling site is located on reach where only very short tributaries, mostly arriving from the apuseni mountains, join the river, therefore the sediments cannot be resetted completely before reaching the mureș (fig. 1 and 4). compared to river arieș the sediments of the târnava (küküllő) are bleached more completely and have a more uniform value (fig. 4). it is possibly related to the fact that the longest tributary of the mureş has a fairly low gradient, therefore channel sediments can go through several cycles of bleaching before arriving to the confluence zone. seemingly, the mixing of low residual dose târnava quartz grains reduces the residual dose level in the sediments of the main river as well, however, that the next sampling point (sample 392 rkm) is 30 km downstream of the confluence (fig. 4). the second, moderate peak in residual dose values (2.56±1.20 gy and 2.35±1.3 gy at 382 and 336, rkm, respectively) can be observed downstream of the confluence of river sebeş (sebes) on a section where the mureş is laterally eroding cretaceous conglomerates and sandstones at the foothills of the metaliferi mountains (fig. 1 and 4). besides, on this section high gradient and short tributaries join the river, which can also explain the presence of less bleached grains in the sediment mixture. a similar phenomenon was identified by tóth et al. (2017) along the danube, where the erosion of loess bluffs resulted an order of magnitude increase in quartz residual doses. on the next 10 km (between 336 and 325 rkm) r esidual dose values drop by 60-70 %, which can hardly be explained solely by the natural bleaching of grains in the channel, but rather by the entering of river strei (sztrigy), which introduces low residual dose sediments to the main river (fig. 4). low values persist till the lipova gate, where river mureş enters the lowlands. here a third peak of residuals appears, which might be explained either by extensive in-channel gravel mining, mostly on the lipova section and downstream, and/or the natural erosion of pleistocene deposits. nevertheless, by reaching the distal part of the alluvial fan, residual doses decrease to their lowest values along the entire investigated reach (fig. 4). luminescence sensitivity the downstream change of luminescence sensitivity, that can be affected either by surface lithology or transportation distance show a similar pattern to that of residual dose values on the upstream reaches of river mureş (fig. 4 and 5). the first two quartz samples (sample 565 rkm and 491 rkm) have practically an identical luminescence sensitivity (154±19 and 159±19 cts/mg/gy). these values fit well to the mean luminescence sensitivity value of five pleistocene age sediment samples (167±9 cts/mg/gy) collected from various points on the alluvial fan of the river and investigated by bartyik et al. (2021). based on this, it could be expected that there is no significant variation in cw-osl sensitivity values along the river. table 1 summary of the measured data of quartz extracts. (in case of tributaries the location refers to the distance from the confluence with the mureş.) river location of sampling points (rkm) grain size (µm) residualdose (gy) normalized cwosl sensitivity (cts/mg/gy) mureş 4 90-300 0.44±0.29 124±22 30 90-300 0.47±0.13 69±16 52 90-300 0.71±0.48 37±5 62 150-220 0.72±0.31 202±60 105 150-220 2.78±0.49 179±47 174 90-300 1.69±9.89 71±10 225 90-150 0.48±0.12 322±34 279 90-150 0.74±0.23 225±26 325 90-150 0.74±.023 232±24 336 90-150 2.56±1.20 132±7 382 90-220 2.35±1.3 139±27 392 150-220 1.35±0.57 124±7 448 90-150 3.88±0.79 587±167 484 90-220 2.36±0.18 305±72 491 90-150 2.07±0.6 158±19 565 90-150 no data 154±19 arieș 486+2 90-150 1.34±0.66 204±13 486+8 90-220 3.21±1.43 294±36 târnava 420+4 90-220 1.01±0.16 146±22 420+14 90-220 0.84±0.36 173±35 strei 327+4 90-150 1.71±0.54 179±15 327+10 150-220 0.57±0.18 118±18 however, values increase considerably going downstream, supposedly by the joining of river arieș (fig. 5), since the luminescence sensitivities of arieș quartz samples are 204±13 cts/mg/gy and 294±36 cts/mg/gy and a very similar value is obtained just below the confluence as well (fig. 5). this way, in the confluence zone the arieș values almost double the level of quartz luminescence sensitivity. moreover, at the next sampling site (448 rkm) the sensitivity reaches its maximum on the entire studied reach (table 1). if surface lithology is considered, the upper catchment of the mureş is dominated by erodible neogene sedimentary rocks, and seemingly the quartz fraction of these has a moderate cw-osl sensitivity. although, the lower reaches of the arieş flow across the same neogene units, its headwaters are in the apuseni mountains and its catchment can be characterized by a complex lithology, comprised mostly of various igneous and metamorphic rocks, such as paragneiss, phillite, basalt and metasomatic granitoids (fig. 1). although, usually quartz originating from igneous and 64 bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. metamorphic rocks has a relatively low luminescence sensitivity (chithambo et al., 2007; guralnik et al., 2015; sawakutchi et al., 2018), on the other hand sawakutchi et al. (2011) emphasized that high crystallization temperatures can its value increase. considering these facts, granitoids affected by metasomatosis, and/or paragneisses metamorphosed from sedimentary rocks can be responsible for the experienced increase in luminescence sensitivity. however, the confirmation of this hypothesis nee ds further sampling in the area. nevertheless, it is also clear from the high standard error of these samples (fig. 5, table 1) that high sensitivity of quartz grains originated from the arieș has limited effect on the overall values of mureș sediments. this can be the reason for the observation that by the entering of târnava cw-osl sensitivity decreases to its original level. the catchment of this tributary is built up by the same neogene sedimentary rocks as that of the mureș, consequently, measured sensitivity values (146±22 and 173±35 cts/mg/gy) are very similar (fig. 5). the high erosive capacity of the river, shown by the increase of residual doses downstream of the târnava is not affecting sensitivity values, thus the quartz of cretaceous conglomerates supposedly has a similar luminescence sensitivity as that of the neogene sedimentary rocks. however, three samples (sample 325, 279 and 225 rkm) collected downstream of the confluence of river strei show an increasing trend again. based on the luminescence sensitivity of quartz grains extracted from strei sediments, this increase cannot be attributed unambiguously to the strei itself (fig. 5, table 1). on the 100 km-long reach represented by the three samples no significant tributaries join the river, and residual doses showed a decreasing trend (fig. 4). it refers to repeated bleaching of quartz grains. in these circumstances it is appealing to claim that sensitivity increase is due to geomorphological reasons. on the other hand, the jump in sensitivity just 2 rkm downstream of the strei confluence and the lithological complexity found on both banks of river mureş points to the possible role of geological reasons. nevertheless, surface lithology on this section is mostly dominated by volcanic rocks such as andesite and basalt, renown of containing low sensitivity quartz in general (sawakutchi et al., 2018), and as the most downstream sample of this section (sample 225 rkm) has the lowest residual dose and the highest cw-osl sensitivity (322±34 cts/mg/gy) from all, the significance of geomorphic factors seems also inevitable. in this sense, the remarkable drop in case of sample 174 rkm (70±10 cts/mg/gy) might refer to the mixing of external sediments, possibly as a consequence of inchannel quarrying and related erosion, as it was suggested on the basis of residual dose increase earlier (fig. 4). it has to be noted also that this sample contained larger quartz grains than any other samples before (table 1), and by the increased degree of self-absorption during osl stimulation this may also contribute to reduced sensitivity values. in case of the following samples (sample 105 and 62 rkm) values tend to grow again (179±47 and 202±60 cts/mg/gy), though with a high standard error, referring again to a nonuniform sensitivity of quartz grains. since, on the basis of residual doses the mixing of palaeo-sediments is suggested on this section, sensitivity increase might be attributed to these. this draws the attention to the potential temporal change in the luminescence sensitivity of channel sediments. it can be explained either by the differential activity of subcatchments under glacial and interglacial climate regimes, or the dynamics of fluvial activity, i.e. the number of sedimentary cycles through which grains arrive to the alluvial fan. to complicate the picture above, luminescence sensitivity values at the edge of the alluvial fan drop again (sample 52 rkm) and reach their minimum fig. 5 normalized cw-osl sensitivity values of the tested samples. bartyik et al. 2021 / journal of environmental geography 14 (1–2), 58–67. 65 (37±5 cts/mg/gy) on the entire studied section (fig. 5, table 1). just like in the case of sample 174 rkm, this and the following two samples are composed of larger quartz grains. consequently, it seems that if maximum grain size of the investigated fraction is above 220 µm then measured values considerably decrease (fig. 6). however, if fractions between 90-150 µm or 150-220 µm are compared then no such tendency can be identified. the analysis of this parameter needs further measurements on different fractions of the same sample. conclusions the combined analysis of quartz osl residual doses, luminescence sensitivity, surface lithology, grain size and transportation distance in terms of modern samples allowed to assess what factors may affect luminescence parameters at most, and if these can be applied late for sediment sourcing and the reconstruction of fluvial processes. in terms of both luminescence parameters it was clearly proven that subcatchment and river reach scale factors can highly influence the downstream variation of luminescence parameters. concerning osl residual doses, in accordance with the general model, by the increase of transportation distance values show a decreasing tendency as a consequence of repeated bleaching. based on the results, local and reach scale increase in values can be related to either 1) short tributaries carrying sediments undergone limited sedimentary cycles; 2) increased erosion of palaeo-sediments and sedimentary rocks by the main river; or 3) in-channel quarrying. all these processes introduce grains with a high palaeo-dose to the sediment mixture of the main river, which then increases the value of the measured residual dose. although, the length of the investigated river reach (565 km) was considerable, no clear downstream increase in luminescence sensitivity was observed as opposed to some previous research (pietsch et al., 2008; fitzsimmons, 2011). according to the data of the present study, sensitivity values showed local and reach scale increase in relation with 1) the inlet of arieş sediments, partly produced from granitoids and paragneiss as opposed to the sediments of the upper mureş originating mostly from neogene sedimentary rocks; 2) repeated sedimentary cycles on reaches where no significant tributaries join the river. differences in surface lithology, therefore, do affect osl sensitivity, but this can be used for sediment sourcing only in case of one out of the three investigated tributaries. meanwhile, the role of transportation distance and sediment recycling cannot be unambiguously confirmed. a major reason for this, is that other parameters, such as the maximum grain size and related self-absorption of investigated quartz extracts can also affect the results. moreover, especially on the lowland section of river mureş unexpected drops in values were experienced, drawing attention to the significance of temporal differences in sediment dynamics and its potential effect on quartz 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of environmental geography 7 (1–2), 29–38. doi: 10.2478/jengeo-2014-0004 issn: 2060-467x autochthonous versus allochthonous organic matter in recent soil c accumulation along a floodplain biogeomorphic gradient: an exploratory study eduardo gonzález 1, 2* , álvaro cabezas 3 , dov corenblit 4, 5 , johannes steiger 4, 5 1 ups, inp, ecolab, université de toulouse, 118 route de narbonne bâtiment 4r1, f-31062 toulouse cedex 9, france 2 cnrs, ecolab, f-31062 toulouse cedex 9, france 3 chemical analytics and biogeochemistry, leibniz institute of freshwater ecosystems and inland fisheries, müggelseedamm 301, 12587, berlin, germany 4 clermont université, ubp, msh, 4 rue ledru, 63057 clermont-ferrand cedex 1, france 5 cnrs, umr geolab – laboratoire de géographie physique et environnementale, 63057 clermont-ferrand, france *corresponding author, e-mail: edusargas@hotmail.com research article, received 25 february 2014, accepted 30 march 2014 abstract the mechanisms controlling soil succession in floodplains remain much less studied than in uplands due to the complexity that flooddriven erosion and sedimentation bring into soil development processes. the amount of organic matter and c generally grows with soil ageing and is controlled by multiple and interacting allogenic and autogenic factors, but to what extent the production of organic matter by in situ vegetation contributes to soil formation in floodplains remains unknown. the objective of this work was to explore the importance of autochthonous organic matter versus allochthonous organic matter in organic c accumulation of floodplain forest soils along a vegetation succession and hydrogeomorphic connectivity gradient. physicochemical analyses of sediment collected after one single flood event in a large mediterranean floodplain (middle ebro, a 9 th order regulated river reach in ne spain) were used to estimate the proportion of organic c found in the topsoil (first 10 cm) samples of young (<25 yr), mature (25-50 yr) and old (>50 yr) floodplain forests that had an allochthonous (i.e., % of organic c deposited by floods) or autochthonous (i.e., % of organic c produced in situ by vegetation) source. results of this exploratory study showed that the accumulation of autochthonous organic c in the floodplain topsoil only occurred in floodplain forests older than 50 year-old, but even then, it was more than six-fold less abundant than that with an allochthonous origin. moreover, a linear mixed effect model showed that, although autochthonous organic c accumulation was mainly explained by the forest structure, a small proportion of it was also controlled by an allogenic factor, the groundwater table depth. then, groundwater table depth variations could be partly controlling autochthonous organic matter production and decomposition in this mediterranean floodplain. although flow regulation and embankment has dramatically limited the hydrogeomorphic dynamics of the river, allogenic overbank sedimentation during flood events still controls floodplain soil succession and organic c accumulation in the floodplain. keywords: floodplain soils, sediment texture, soil organic carbon, overbank sedimentation introduction organic matter accumulation within floodplains is an ecosystem function that provides important benefits such as water quality enhancement or mitigation of greenhouse effect (johnston, 1991; day et al., 2004; verhoeven et al., 2006; ipcc, 2007). soil organic matter is especially relevant since it forms a larger and more lasting pool than living biomass. however, soil successional patterns have been much less studied in floodplains than in upland forests (wigginton et al., 2000). the main reason is that successional trajectories in floodplains are recurrently brought to a starting point by destructive floods (hughes et al., 1997; geerling et al., 2006; cabezas et al., 2009a), thus making the forest floor development much more unpredictable than in the more stable uplands. the role of floodplain soils as sink or source of organic c varies along the longitudinal river axis, with downstream river sections importing the suspended sediment and a part of organic matter of the upstream sections of the catchment (steiger and gurnell, 2003; noe and hupp, 2005). along the transversal river axis, from the water channel to the floodplain, flood events determine the role of a given ecotope as sink or source of organic matter as well as its source (allochtonous vs. autochthonous) for a given study period. organic matter produced by biotic assemblages is incorporated into surface soils during the intervals between overbank flooding. during floods, low-organic fluvial sediments may be deposited on floodplain landforms, and the organic matter that had been stored in different compartments such as the soil or standing vegetation is either exported or buried (cabezas and comín, 2010), maintaining the soil in a continuous immature state (drouin et al., 2011). as vegetation develops in the absence of destructive floods, the floodplain surface roughness increases and enhances sediment deposition, which in turn causes its elevation in relation to the river channel to rise (hupp, 2000; bendix and hupp, 2000; steiger et al., 2001). sandy sediment trapping by young and 30 gonzález et al. (2014) dense thickets of vegetation predominates in the most exposed zones, while organic matter produced in situ may be more easily retained in less exposed zones such as the hydrologically disconnected floodplain. overbank sedimentation of fine sediment esp ecially favors the accumulation of organic c in the soil as organic matter forms easily complexes with fine sediment (silt and clay <63 µm) (asselman and mi ddelkoop, 1995; steiger and gurnell, 2003), silt and clay fraction and organic carbon being positively correlated (pinay et al., 1992; bechtold and naiman, 2006). however, accretion is also negatively feed backed by hydrological disconnection (bendix and hupp, 2000). both increasing distance to and elevation above the main channel generally contribute to the decrease in duration and frequency of flooding (corenblit et al., 2007), eventually leading to a d ecrease in the input of sediment and organic matter bounded to sediment particles (i.e., allochthonous organic matter) (asselman and middlekoop, 1995; walling and he, 1997; piégay et al., 2008; cabezas et al., 2010). in other words, the input of organic c in a given forest patch via sedimentation is limited to areas that are hydrogeomorphologically connected to the main channel. on the other hand, as floodplain forest succession and hydrogeomorphic disconnection develop, litter (i.e., authochthonous organic matter) accumulates in the topsoil because it is less likely to be intensively and frequently removed by floods (friedman et al., 1996). it follows that similar to floodplain vegetation dynamics (corenblit et al., 2007), the soil development and organic c accumul ation is driven mainly by abiotic factors at the early stages of soil succession, implicating that during the allogenic vegetation succession stage allochthonous organic matter dominates. but if these hydroge omorphic drivers are gradually replaced by biotic fa ctors in later stages of succession, i.e. late -seral stages, it is expected that during autogenic succession stages autochthonous organic matter dominates. this theore tical framework of soil succession would fit with cla ssic succession theory (clements, 1916). however, studies devoted to quantify these processes wit hin floodplain zones have not been frequent, and the relative roles of abiotic (hydrology, topography and sed iment dynamics) and biotic (forest structure) factors as drivers of organic c dynamics in floodplain soil d evelopment remain largely unknown (but see cie rjacks et al., 2011). more particularly, although it is widely recognized that floodplains are highly productive ecosystems (naiman et al., 2005), little is known about how much autochthonous sources contribute to organic c accumulation locally. in fact, the efforts done to understand patterns of organic c accumul ation in floodplain soils have rarely considered autoc hthonous and allochthonous sources separately (but see daniels, 2003; cabezas and comín, 2010). the objective of this study was to evaluate the relative importance of autochthonous vs. allochthonous organic c (respectively autoc and alloc) along a vegetation succession and hydrogeomorphic connectivity gradient (a biogeomorphic gradient sensu corenblit et al. 2007) in the soil of a large forested floodplain. alloc was expected to be more important at the more connected and younger sites, with abiotic factors driving succession (corenblit et al., 2007) and autoc higher at disconnected and older forest patches, with biotic factors driving succession (corenblit et al., 2007). study area the study was carried out in an 8 km river segment in the middle ebro river. the segment was located 12 km downstream from the city of zaragoza (41º36’ n, 0º46’ w, 175-185 m a.s.l., ne spain). the ebro river is one of the largest mediterranean rivers in terms of length (~930 km), annual discharge (~12 000 hm 3 yr -1 ) and drainage area (~86 000 km 2 ). the hydrological regime is pluvio-nival and the river is highly regulated by dams built for irrigation and flood control during the 1950’s and 1960’s. at the river gauge station of zar agoza, the annual mean of the daily flow discharge between 1981 and 2003 is 230 m 3 s -1 . as a consequence of flow regulation, a decrease in bankfull discharge and in the duration and frequency of overb ank flooding events throughout the second half of the 20 th century was observed (cabezas et al., 2009a). both the selected river segment and the middle reach of the ebro have a very limited channel migration rate since the 1970’s and 1980’s, due to two decades of intense bank protection works (ollero, 2007; magdaleno and fernández, 2011). however, the middle reach of the ebro still maintains a sinuous shape (sinuosity = 1.39, mean longitudinal channel slope = 0.05 %, ollero, 1995) as a relict of the former dynamic geomorphic regime before river training works. the average width of the submersible floodplain is 5 km but agriculture and human settlements have reduced the surface occupied by natural floodplain forest to ~4.5% of the floodplain surface (ollero, 2007), usually occupying the inside of meander bends, which are not protected by bank protection works. despite protection by levees, floodplain forests on both the convex and concave river banks are inundated by floods with recurrence intervals of <10 years (1981-2003). tree communities are dominated by phreatophytic species (populus alba l., populus nigra l., salix alba l., tamarix gallica l., t. africana poir. and tamarix canariensis willd.). late-seral hardwood species (ulmus minor auct. non p. mill. and fraxinus angustifolia vahl) are commonly found, but usually with size stems smaller than 7.5 cm d.b.h. (gonzález et al., 2010a). methods plot selection along a vegetation succession and hydrogeomorphic gradient using a series of aerial photographs (1957, 1981 and 2003), 39 forest patches of different age: young (<25 years, 13 patches), mature (25-50 years, 13 patches) autochthonous versus allochthonous organic matter in recent soil c accumulation … 31 and old (>50 years, 13 patches), all subjected to ann ual flooding along a hydrogeomorphic gradient, were selected for this study (fig. 1). one rectangular study plot was randomly placed within each forest patch to carry out a tree survey in 2006 and 2007, including the diameter and species record of every woody stem ≥ 0.3 m height (total = 6891 stems) (gonzález et al., 2010a). plot dimensions were scaled according to the dominant tree height and ranged from 25 to 1000 m 2 . the collected information was used to calculate total and species-specific basal areas (ba, m 2 ha -1 ) and stem densities (sd, stems ha -1 ) following gonzález et al. (2010a). species-specific importance values (iv) were then calculated at each plot using a modification of the gergel et al. (2002) formula, ranging from 0 (absence) to 1 (complete dominance): ivi = [(sd of species i / total sd) + (ba of species i / total ba)] / 2. to describe the hydrogeomorphic regime at each plot, a network of 17 piezometers was installed in the floodplain (details in gonzález et al., 2012). water levels in the piezometers were continuously monitored from october 2008 to september 2010 (highest flood peak recorded at the gauging station of zaragoza during the monitoring period: 1506 m 3 s -1 , february 2009, recurrence interval for the 1927-2003 period: 0.87 yrs) using integrated absolute pressure sensors and data loggers (van essen di502 td diver®), which permit the determination of groundwater table depths as well as water stages above piezometers during inundation and thus above the floodplain surface. hereafter the synonym ‘water table’ was used for groundwater table and ‘floodwater stage’ for water stage above piezometers during inundation. the piezometer measurements were used to interpolate the water table levels and floodwater stages and, following gonzález et al. (2012), to determine the deepest water table level recorded (wt, m), flood duration (fd, % of the time) and flood frequency (ff, number of flood submersions) that represented the local hydrologic regime at each plot during the study period. the piezometer and plot elevations above sea level (elev, m) and the utm coordinates necessary for all calculations had previously been recorded using a differential global positioning system (dgps) topcon® with 3 cm vertical accuracy. the shortest distance from the centroid of each plot to the main river channel at the summer level (dist, m) was calculated using arcgis 9.2. topsoil collection and processing soil samples were taken at the end of the vegetation growing season in september and october 2006, coi nciding with low water levels prior to autumn floods and before the main peak of litterfall that typically occurs in november in the study area (gonzález, 2012a). this sampling period was chosen to minimize the influence of the litter fall over the soil organic matter analyses, thus focusing on the consolidated organic matter soil pool. at each plot, three topsoil (0–10 cm) samples were collected using an undisturbed soil sampler (5 cm diameter steel tube, p.1.31 eijkelkamp®) after carefully removing the living vegetation and litter layers. at the larger plots (>500 m 2 , 6 plots), more samples were collected to obtain a composite of three samples that better represented the heterogeneity of the soil in the plot. samples were air dried before being passed through a 2 mm sieve to remove rock and larger organic matter fragments. total organic c (toc, %) was measured with a leco sc 144 dr® elemental analyzer. the fine fraction (i.e., fine silt + clay, % of particles <63 μm) was calculated gravimetrically by sieving sub-samples fig. 1 location of the study sites in a 8 km segment of the ebro river. the aerial picture was taken in 2007. lines correspond to the main channel tracks in 1957 and 1981 32 gonzález et al. (2014) of the < 2 mm material into a 63 µm screen previously treated with a 10% hydrogen peroxide solution to eliminate the organic matter and with a polyphosphate solution to facilitate particle dispersio n. in young plots, a framework of gravels, cobbles and/or boulders was usually present in the surface layer and the soil sampler could not be used. then, the soil analyses were performed using the finer sediments filling the pore spaces between the framework grains. determination of alloc and autoc the particle-size composition of sediments partially determines the amount of organic c that is deposited locally during floods. the sediment deposited during one flood event was collected using 92 sediment traps made of artificial grass mats (25 x 25 cm) set up in 3 meanders of the study area (fig. 1). details on the experimental setup can be found in cabezas et al. (2010). artificial grass mats have been commonly used to study contemporary sedimentation rates in river floodplains, especially when it was necessary to recover the sediment deposited during one individual flood event as in the present study (see steiger et al. 2003 for a review). the flood occurred in january 2006 and lasted for 8 days. it had a flood peak at the gauging station of zaragoza of 754 m 3 s -1 and a recurrence interval for the 1927-2003 period of 0.23 yrs. a few days after the flood, mats re-emerged with only 7% of them having been flushed away by the river. mats were collected, brought to the laboratory and oven-dried at 60 ºc. the deposited sediment was then carefully removed by hand using a metallic brush and their proportion of fine particles and toc determined as described above for the topsoil samples. a polynomial function was adjusted to model the relationship between the fine fraction and toc measured in the sediment gathered from the mats. the function served to calculate the theoretical proportion of toc that was deposited during floods at each topsoil sample in the 39 study plots (i.e., alloc), using the fine fraction as independent variable. in other words, it was considered that the alloc within a given topsoil sample could be predicted as a function of its grain size (pinay et al., 1992; bechtold and naiman, 2006; cabezas and comín, 2010). it follows that the difference between observed and predicted toc values (toc residuals) would be an indicator of the organic c produced and accumulated in situ at each topsoil sample (i.e., autoc). our objective was not to calculate absolute organic c accumulation rates, which would have also required to measure local sedimentation rates, which was not done here. instead, the aim was to obtain a quantitative estimate of the accumulated organic c that had been produced in situ (toc residual = autoc), compared to the accumulated organic c deposited by floods (predicted toc = alloc). negative values in the toc residuals of some plots were an unavoidable artifact of our experimental approach and were explained by the fact that the floods that were actually responsible for the alloc deposition in those plots contained a lower organic content than the flood used to build the predictive function. however, negative toc residuals were interpreted as indicators of a lower probability of having autoc accumulation (or as a higher certitude in the absence of autoc accumulation) and were included in the analyses explained below. evaluating the relative importance of autoc vs. alloc along the biogeomorphic gradient in a first step, predicted and observed toc values were plotted together grouped by plot age and, within each age category, their medians compared by means of nonparametric wilcoxon matched-pairs signed-ranks tests. therefore, it was examined whether erosionsedimentation processes controlled only the toc topsoil levels (i.e., that if predicted and observed toc values were not significantly different, no autoc was accumulated) or whether an accumulation of autoc effectively occurred (i.e., that observed toc values were significantly higher than the predicted toc values) along the floodplain forest chronosequence. the significance levels were set up at 0.05. statistical modeling of autoc accumulation once evaluated the relative importance of autoc vs. alloc along the biogeomorphic gradient, the infl uence of abiotic and biotic factors on the var iability of the toc residuals was assessed using linear mixed effect models (lme, pinheiro and bates, 2000) and hierarchical partitioning. lme are a type of multiple regression that do not assume that all observatio ns are independent from each other, and so can be used to analyze data from clustered experimental designs where observed subjects are nested within larger units. different lme models were run using all the variables representing the vegetation succession and hydrological connectivity (table 1) as fixed factors, plot as random effect, and toc residuals as the d ependent variable, with n = 117 (39 forest plots x 3 topsoil replicates). a backward selection of predictors was performed to retain only the most significant (p < 0.05) explaining the response of toc residual, testing each step with a likelihood ratio-test (crawley, 2002). pearson’s product–moment correlation between the observed and predicted values and the akaike info rmation criterion were used to assess the goodness-offit of the final models. once identified the main pr edictors, the sum of independent and shared variance in the toc residuals explained by each significant pr edictor (i.e., the relative contribution) in each model was assessed through hierarchical partitioning (chevan and sutherland, 1991). the lme models and hierarchical partitioning were run using functions available in the package “nlme” (pinheiro et al., 2007) and “hier.part” (walsh and mcnally, 2007) of the r 2.14.0 software (r development core team 2011). different transformations were applied to the explan atory variables to correct for the effect of asymmetry, given that most of them were not normally distributed (kolmogorov-smirnov test). the exploratory analyses showed that toc residuals had a strong positive and heteroscedastic relationship with “observed toc” (i.e., higher toc residuals and higher variance were observed at higher toc values). to remove that co n autochthonous versus allochthonous organic matter in recent soil c accumulation … 33 founding effect, “observed toc” was included in the models as covariable. all variables were standardized before running the models. results forest succession and hydrogeomorphic gradient the classification of plots into three age-groups along a forest succession and hydrological connectivity gradient fitted with their forest structure and with their local hydrological connectivity descriptors, with significant differences between young, mature and old plots in all variables reported (table 1). young plots were dominated by pioneer tree species populus nigra, tamarix spp. and salix alba (sum of their iv = 0.99) and were in a very active recruitment phase, as shown by their significantly higher stem density and lower basal area compared to mature and old plots. this reflected the prevalence of small stems in the forest structure. compared to the older plots, young plots also displayed the highest hydrological connectivity, with a significantly higher water table, flood duration and frequency as direct consequences of their lower topographical position and shorter distance to the main channel. mature plots represented an intermediate successional stage along the chronosequence. pioneer species were still dominating (sum of their iv = 0.81) but formed less dense patches than in young plots (stem density decreased eight-fold while basal area slightly increased). in addition, lateseral stage species, namely ulmus minor and fraxinus angustifolia, were now more frequent. the higher elevation plots in the floodplain were located at a greater distance from the main channel and were three-fold less flooded (in terms of duration) than young plots. within the mature plots, the lowest water tables recorded were 1 m deeper on average than in the young plots, but flood events were still frequent. in the old plots pioneer species did not dominate (sum of their iv = 0.44), although not only as a result of their replacement by late-seral species (iv = 0.25) but also caused by the appearance of a new successional pathway dominated by populus alba (present in 7 out of the 13 old plots surveyed). old plots were the hydrologically most disconnected sites along the chronosequence, being rarely flooded and with lowest water tables recorded reaching a mean depth of ~3.5 m below the floodplain surface. topsoil overall, the soil descriptors also followed the biogeomorphic gradient (table 1). sandy soils predominated in young sites. however, mature and old topsoil forests table 1 summary of the forest structure and hydrological connectivity descriptors for 39 forest patches divided into three age categories: young, mature and old. values are means ± 1 se. letters indicate homogeneous groups after independent t tests implemented in spss v 13.0 (p < 0.05) young mature old n 13 13 13 age (years) <25 25-50 >50 plot size (m 2 ) 130 b ± 33 386 a ± 21 545 a ± 86 forest structure basal area (ba, m 2 ha -1 ) 34 b ± 8 48 ab ± 7 67 a ± 11 stem density (sd, stems ha -1 ) 26395 a ± 8365 3270 b ± 749 5771 b ± 1178 iv (unitless) populus nigra (ivpn) 0.48 a ± 0.10 0.35 ab ± 0.07 0.18 b ± 0.07 populus alba (ivpa) 0.00 b ± 0.00 0.00 b ± 0.00 0.30 a ± 0.10 tamarix spp. (ivtx) 0.42 a ± 0.10 0.29 a ± 0.08 0.24 a ± 0.08 salix alba (ivsa) 0.09 a ± 0.03 0.17 a ± 0.08 0.02 a ± 0.01 fraxinus angustifolia (ivfx) 0.01 b ± 0.00 0.11 a ± 0.03 0.03 b ± 0.01 ulmus minor (ivum) 0.00 c ± 0.00 0.07 b ± 0.02 0.21 a ± 0.05 other species (ivot) 0.00 b ± 0.00 0.01 ab ± 0.00 0.01 a ± 0.00 hydrological connectivity maximum depth to water table (wt, m) 1.28 c ± 0.15 2.25 b ± 0.19 3.49 a ± 0.21 flood duration (fd, % of time) 24 a ± 4 9 b ± 3 2 c ± 1 flood frequency (ff, events y -1 ) 5 a ± 1 4 b ± 0 2 c ± 0 topography elevation a.s.l. (elev, m) 178 b ± 1 180 a ± 0 181 a ± 0 distance to river channel (dist, m) 42 c ± 10 117 b ± 22 221 a ± 37 topsoil (first 10 cm) total organic carbon (toc, %) 1.22 c ± 0.16 2.28 b ± 0.11 2.73 a ± 0.18 fine fraction (fine, %) 47 b ± 7 88 a ± 3 86 a ± 5 34 gonzález et al. (2014) were basically composed of fine sediment. toc progressively increased along the chronosequence starting at young sites near the river channel. determination of alloc and autoc the fine-texture of the sediment deposited on the mats by the studied flood event was positively correlated with the associated toc deposited following a quadratic relationship (fig. 2). the polynomial function predicted well the proportion of organic c contained in the topsoil samples of the young and mature forests (no significant differences were found between predicted and observed toc median values after wilcoxon tests, fig. 3). fig. 2 scatter plot of sediment texture (silt plus clay, %) and total organic carbon (toc, %) in the sediments deposited during a flood on 1 january 2006 in the study area that means that all the organic c had an allochthonous origin and no autoc was being accumulated in the plots < 50 year-old. on the contrary, the function under-estimated the proportion of organic c that was found in the topsoil of the old age-forest category (> 50 year-old). that is, the observed toc median was significantly higher than the predicted toc median (fig. 3). this fact was interpreted as a proof of a significant accumulation of autoc. however, even in this situation, the contribution of the autochthonous fraction to the organic c stock was more than six-fold lower than that of the allochthonous origin (median toc residual in old plots, autoc = 0.41%; median predicted toc in old plots, alloc = 2.64%). fig 3 observed and predicted toc values from equation in fig. 2 along a biogeomorphic gradient. wilcoxon matchedpairs signed-ranks tests were used to compare the median value of the observed and predicted toc values of each age-forest category, with their z-values and probability associated represented in the figure modeling the accumulation of autoc the capacity of the 14 parameters representing the forest structure and hydrological connectivity gradients (table 1) as predictors of autoc was first tested individually using spearman correlation tests and controlling for the effect of “observed toc” on “toc residuals” (toc residuals = -0.275 + 0.206 * observed toc; f1,109=18.94; r 2 = 0.14; p < 0.001). only three variables had a significant correlation with the toc residuals, namely sd (ρ = 0.30), ivfx (ρ = -0.44) and ivsa (ρ = 0.24) at a p < 0.05. however, a lme model could be significantly fitted to the whole dataset and is summarized in table 2. the model explained 24% of the variability in autoc with a combination of three forest structure variables and one hydrological connectivity table 2 result of the best lme model run between autochthonous organic c accumulated in the first 10 cm of soil (response variable) and different forest structure and hydrological connectivity surrogates (table 1, fixed factors) and plot as random effect. note that the degrees of freedom are only 109 because six outliers were removed from the initial 117 soil samples (39 plots x 3 soil replicates) due to their abnormally high or low toc values model fit pearson’s correlation explanatory terms type of predictor relationship sign p-value relative contribution autoc (% of oc with an autochthonous origin) aic = 269.6525 r 2 =0.24 t=5.9271 d.f.=109 p<0.001 logivfx forest structure 0.0002 39% logsd forest structure + 0.0006 27% wt hydrological connectivity + 0.0001 24% logivpn forest structure + 0.0036 10% autochthonous versus allochthonous organic matter in recent soil c accumulation … 35 variable. in particular, it predicted higher autoc accumulation with lower relative dominance of fraxinus angustifolia, higher stem densities, higher importance of populus nigra (the three relationships following a logarithmic ratio) and deeper water table levels (i.e., less subsurface hydrological connection). the joint contribution to the model of the forest structure variables was 76%, versus 24% explained by the hydrogeomorphic regime surrogate. six topsoil samples of the 117 that originated from randomly distributed plots of young and old forest patches were considered to be outliers and therefore removed from the statistical analyses. the analytical results obtained for the samples showed abnormally low or high toc values detected during the exploration of the residuals of preliminary models and assumed to be incorrectly collected in the field. discussion organic c that accumulates in the floodplain soil had a predominant allochthonous origin the results of our study suggest that most of the organic c that accumulated in the forested floodplain soils had an allochthonous origin; presumably from flood-driven sedimentation processes. this occurred even at the more disconnected sites that were only flooded twice a year and where the forest had established for several decades. in particular, alloc a ccumulation was more than six times more important than autoc in forests older than 50 years. at the more connected and younger sites, it was impossible to identify any accumulation of organic c in the soil produced by in situ vegetation, reflecting that its importance was marginal relative to that deposited by floods. this was a surprising result as far as vertical litterfall in the ebro (563 g dry matter m -2 yr -1 ) is an important input of organic matter in the floodplain that is within the range of litterfall values reported in other mediterranean riparian settings and floodplain forests of the warm temperate zone (gonzalez et al., 2010b). although the river has dramatically lost its geomorphic dynamics since the 1980’s (cabezas et al., 2009a), sedimentation still plays a much more important role in organic c accumulation than the autochthonous organic matter produced in situ by vegetation. our results provide evidence to support that alloc tends to dominate along the floodplain despite flow regulation and embankment, as long as it remains connected with quasi-annual floods (return period of 2.33 yrs. sensu osterkamp and hedman, 1982). however, this conclusion does not imply that the loss of geomorphic dynamics caused by human impacts on the river system has not had an effect on alloc accumulation. in fact, cabezas et al. (2009b) showed within the same river reach of the middle ebro river, that alloc floodplain accumulation rates within a floodplain forest patch dating from at least 1957 and in two oxbow lakes with an origin <1946 were higher before completion of dam co nstructions built for flood risk reduction and river trai ning works (<1963). dams and river training works did not prevent overbank flooding and thus it could have been expected that alloc accumulation within the studied forest patch and the two oxbow lakes did not decrease. river training works implied the cutting off of meanders, partially disconnecting the forest patch and the oxbow lakes from the main channel and thus being less frequently flooded. relative role of the abiotic and biotic factors in controlling autoc accumulation according to our results, we suggest that organic c accumulation was controlled mainly by allogenic forces, namely the hydrological regime that ultimately controlled the sedimentation processes. the role of vegetation in organic c accumulation would be more important as a consequence of its physical modulation of hydrogeomorphic fluxes rather than of its own primary productivity, even at the more disconnected and older sites, where late-seral successional stages of vegetation dominated. the presence of non-pioneer trees such as fraxinus angustifolia and ulmus minor at the older sites seems to indicate that vegetation develops autogenically. however, our results suggested that, even then, the soil evolved mainly allogenically. whether the vegetation and soil succession drivers are uncoupled or the non-pioneer species are much more controlled by the hydrological regime than expected remains an open question that deserves further study. unlike pioneer riparian tree species, the ecology of non-pioneer floodplain tree species has surprisingly received very little attention up to date. the capacity of the hydrological regime as driver of organic c accumulation goes beyond its influence on sedimentation processes since surface and sub-surface hydrological connectivity partially controls the accumulation of autoc as well. our lme model showed that a higher accumulation of autoc occurs with deeper water tables. deeper water tables were correlated with lower flood frequency and duration, probably resulting in lower sedimentation and in turn in a decrease of the importance of alloc vs. autoc along the biogeomorphic gradient from the channel to the outer floodplain. however, a further explanation of this relationship may also be the control exerted by the hydrologic regime both on the production of organic c and on its decomposition. numerous studies have shown that primary production of floodplain forests and forested wetlands is largely controlled by the hydrologic regime (megonigal, et al. 1997, burke et al., 1999, clawson et al., 2001 and many others). in our study area, gonzález et al. (2010b; 2010c; 2012b) showed that the flooding regime explained up to 35% of the litter production variability, directly or indirectly by its effects on the n and p cycles. they also found a weak but positive relationship between deeper water levels and litter production. therefore, the higher accumulation of autoc with deeper water levels in our lme model could be partly due to a higher litter production in those more oxygenated soils. the influence of hydrological connectivity on organic matter decomposition, and hence on the c cycle, has also 36 gonzález et al. (2014) been proven before (e.g., baker et al., 2001; ozalp et al., 2007). recurrent floods alternating aerobic conditions are supposed to favor organic matter decomposition (brinson, 1981; lockaby et al., 1996). it might be the case that deep water tables in our old plots (>50 yr) did not enhance those wetting and drying cycles and hence slowed down decomposition and favored organic c accumulation. no differences in the magnitude of water table fluctuations were observed between plots in the relatively small study area. therefore, this variable did not contribute to the models and was not shown. however, water table fluctuations at sites with deep water tables are related to less flood submersion episodes than at sites with higher water tables (see wt and ff, table 1). although it was out of the scope of our study, decomposition must play a key role in the c net accumulation over the long-term in the floodplain soils. with shallower water tables, the young (<25 yrs.) and mature (25-50 yrs.) plots may also be experiencing higher decomposition rates, ultimately reducing c accumulation. although the subsurface hydrological connectivity by means of the water table depth below the floodplain surface explained part of the variability in the accumulation of autoc, it was the forest structure that most contributed (76%) to the adjusted lme model. the positive effect of stem density on c accumulation was also probably the result of the higher litter production that exhibit floodplain forest patches with higher stem density (gonzalez et al., 2010b). the inclusion of the iv of f. angustifolia and p. nigra in the models might respond to a lower productivity and faster decomposability of the organic matter produced by the former and to a higher productivity and lower decomposability for the later (see respective negative and positive contributions in the lme model, table 2), but more studies should be done to confirm this hypothesis. limitations of the study an important limitation of our study may come from the fact that only the first 10 cm of the soil were collected. in certain locations it may have occurred that one single flood event deposited more than 10 cm of sediment, burying the organic c produced in situ. in that case, our methodology could have underestimated the autoc because it assumed that the topsoil is representative of a likely heterogeneous soil profile (cooper et al., 1999; cierjacks et al., 2011). however, this limitation would probably only affect the sites where accumulation is higher than erosion. for example, most of the young plots were covered by gravel, cobbles or sand depositions, and it is very unlikely that a much less denser material such as organic matter has been buried instead of been flushed away. even at sites where net accretion occurred in our study area, it has been shown that it does at a rate much lower than 10 cm yr -1 (cabezas et al., 2009b) and that the higher rates are localized on narrow margins adjacent to the main channel and on small areas that were the first to be submerged during overbank flooding (cabezas et al., 2010). another source of error may have come from our predictive function alloc = f(fine-texture) that was built from one single flood event only and could have been biased towards the alloc or autoc fraction if its organic matter load was respectively higher or lower than the average of all floods. different flood events may have different sediment-toc relationships depending on the flood characteristics in respect to magnitude and flow depths and velocities, timing, frequency, as well as sediment availability and fluxes. although this is a major limitation of our study, the marginal weight of autoc relative to alloc (more than six times lower) allows the assumption that with a more consistent predictive function even major deviances from our estimate values would not substantially change the conclusions drawn from our work. for example, the sampled flood in january 2006 did not inundate all 39 plots. thus, if larger floods inundating all these plots had been sampled and included in the fine sediment fraction-toc function for alloc, the sedimentation pattern would have represented the entire floodplain. furthermore, this would partially account for the effect of the high spatial variability of sedimentation dynamics and quality (cabezas et al., 2010). unfortunately, it is hard to predict the timing of high magnitude, exceptional floods, which makes logistics regarding sample design, i.e. the setup of mats covering the whole natural hydrogeomorphic gradient in the floodplain, very difficult. our approach also assumed that the relationship between toc and the fine sediment fraction was constant during the 50 years covered by the chronosequence. given that flood control measures have been carried out for decades, sediment sources and availability controlling quantities and quality (e.g. texture, organic matter content) of overbank deposits might have changed over the years. we believe that this assumption, as well as the fact that our model was based on one single flood sampled only, may have influenced our alloc/autoc ratio quantitatively, but not qualitatively. because of the limitations of this exploratory study, the soil texture method applied to identify autochthonous vs. allochthonous c in floodplains (cabezas and comín, 2010) needs to be further validated in order to be used more widely within different biogeomorphological settings and according to varying flood characteristics. it would benefit from future comparisons with alternative methods of partitioning autoc and alloc, such as exploring c budgeting (c depositional fluxes, litterfall fluxes, litterfall decomposition and soil respiration) and c/n ratios, carrying out isotopic characterization or expressing soil c net accumulation rates on a mass basis (g c m -2 yr -1 ) instead of a relative concentration (%). conclusions this study showed that the accumulation of autochthonous organic c in the ebro floodplain topsoil only occurred in floodplain forests older than 50 year-old, but even then, it was more than six-fold less abundant than that with an allochthonous origin. flow regulation and embankment may have substantially reduced the hydrogeomorphic dynamism of the river, but sedimentation by overbank flooding still occurs and probably controls floodplain soil succession and organic c accumulation in autochthonous versus allochthonous organic matter in recent soil c accumulation … 37 the floodplain. despite the abovementioned limitations of the present study, a promising method to distinguish the relative contributions of autochthonous versus allochthonous c in floodplains was presented here. thus, this study eventually contributes to the better insights of the role of floodplains in the overall carbon budget and in providing ecosystem services, such as water quality improvement or climate regulation. acknowledgements the authors thank d 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sedimentation on river floodplains. water, air and soil pollution 99, 9–20. doi: 10.1007/bf02406840 walsh, c., mcnally, r. 2007. hier.part: hierarchical partitioning. r package version 1.0–2. available from www.r-project.org. wigginton, j.d., lockaby, b.g., trettin, c.c. 2000. soil organic matter formation and sequestration across a forested floodplain chronosequence. ecological engineering 15, s141–s155. doi: 10.1016/s0925-8574(99)00080-4 http://www.agu.org/pubs/crossref/2008/2006wr005260.shtml http://www.r-project.org/ http://www.r-project.org/ http://www.r-project.org/ changes in floodplain vegetation density and the impact of invasive amorpha fruticosa on flood conveyance journal of environmental geography 11 (3–4), 3–12. doi: 10.2478/jengeo-2018-0008 issn 2060-467x changes in floodplain vegetation density and the impact of invasive amorpha fruticosa on flood conveyance judit nagy1, tímea kiss1*, istván fehérváry2, csaba vaszkó 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2lower tisza district water directorate, stefánia 4, h-6720 szeged, hungary *corresponding author, e-mail: kisstimi@gmail.com research article, received 24 july 2018, accepted 31 october 2018 abstract flood conveyance of floodplains is significantly influenced by the riparian vegetation cover, since vegetation affects flow velocity, therefore has a considerable impact on flood height and rate and pattern of sedimentation. however, climate change promotes the spread of invasive species, and their rapid growth results in dense vegetation stands, thus they have a significant impact on floodwater hydraulics. the aims of the present study are (1) to analyse the long -term changes in land-use and vegetation density on the lower tisza river, (2) to evaluate the role of the invasive amorpha fruticosa in increasing vegetation density, and (3) to model the effect of dense floodplain vegetation on flood level and flood conveyance. long -term (1784-2017) changes of land-use suggest that in natural conditions the study area was occupied by wetlands (92%), thus water covered the area for almost the whole year. in the 19th century, after levee constructions the wetlands were replaced by meadows and pastures (94%), then by the end of the 20th century planted and riparian forests replaced these land -covers. as a result, the mean roughness (0.14) of the floodplain has increased threefold until the early 21 st century. today forests are invaded by amorpha fruticosa, which increases the vegetation density by 3% in riparian forests, by 23% in forest plantations, and by up to 100% in abandoned pastures and a rable lands. according to the results of hec-ras (hydrologic engineering center's river analysis system) and ces (conveyance estimation system) models, if floodplain vegetation was managed and amorpha fruticosa was cleared from the floodplain, peak flood level would decrease by 15 cm. due to dense vegetation, the flood conveyance decreased by 4 -6%, and the presence of amorpha fruticosa reduced the flood flow velocities by 0.014-0.016 m/s. accordingly, clearance of the floodplain from amorpha fruticosa would have positive effects on flood protection, since peak flood stages would decrease and flood waves would shorten . keywords: vegetation, roughness, floodplain, forests, amorpha fruticosa introduction the climate change and the resulted hydro-climatological extremities facilitates the spread of invasive species, thus they appear in large number and due to their rapid growth they form very dense vegetation stands, thus they have a significant impact on the ecosystem (didham et al., 2005) and on vegetation density (delai et al., 2018), resulting in changes in floodwater hydraulics. one of the most important elements of effective floodplain management and flood protection is providing unobstructed flood conveyance on floodplains (samuels et al., 2002). flood conveyance of floodplains is influenced by several local factors, e.g. water surface width, the floodplain’s surface roughness, built-in structures, and floodplain aggradation (rátky and rátky, 2009). the roughness of the floodplain’s surface is significantly influenced by vegetation, as plants could alter flow conditions and affect flow velocities (osterkamp and hupp, 2010; takuya et al., 2014; devi and kumar, 2016). as a result, dense vegetation significantly reduces flow velocity, which combined with accelerated sedimentation, deteriorates the flood conveyance on floodplains (chow, 1959). this could result in increased flood levels, thus increased flood risk (wang et al., 2015). the impact of vegetation on flow conditions is complex, as it depends on the density and height of the vegetation, on its phenological phase, morphological and structural characteristics (chow, 1959; wang et al., 2015; vargas-luna et al., 2015). vegetation density is primarily determined by the species (antonarakis et al., 2010), the number and rigidity of stems (freeman et al., 2000; galema, 2009), and the density of foliage (ree and crow, 1977; järvelä, 2004; antonarakis et al., 2010), thus it can vary by season (burkham, 1976; coon, 1998). the denser vegetation and more rigid stems create greater obstructions to flood flow, resulting in reduced flow velocity. in extreme cases (very dense vegetation and low water slope) the flow velocity can be reduced to 0 m/s (sándor and kiss, 2007). decrease in flow velocity depending on the height of the vegetation cover, as if the height of inundation exceeds the height of the vegetation, the flow velocity can recover to normal, since there is no obstruction in the flow direction (galema, 2009). floodplains provide optimal conditions for the spread of invasives, since these species survive periodical inundations, and their seeds can travel large distances by the floods invading farther areas (pyšek and prach, 1994). invasive species tolerate burial by deposits (schnitzler et al. 2007), extreme hydrological conditions, and they favour 4 nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. sunlight (dumitraşcu et al., 2012). human activities on floodplains also promote their dispersal, as new invasive species are often introduced, besides deforestation and abandonment of lands could help their invasions too (pyšek and prach, 1993; planty-tabacchi et al., 1996; szigetvári, 2002; mihály and botta-dukát, 2004). high and long-lasting floods could be such a high magnitude of disturbing effects, that native species cannot necessarily tolerate (catford and jansson, 2014; garssen, et al. 2015). on the lower tisza river in hungary, for instance, floodplains can be inundated by 6-8 m high floods for 1-3 months, which has promoted the dispersal of invasive species, such as amorpha fruticosa, echinocystis lobata and vitis vulpina. nowadays, these species form very dense, impenetrable shrubbery in many areas on the floodplain (fig. 1). fig. 1 (a) mainly invasive species form impenetrable shrubbery and (b) amorpha fruticosa bushes under a poplar plantation (lower tisza river, hungary) along the tisza river amorpha fruticosa causes the greatest problems, as it spreads very aggressively on the floodplain (mihály and botta-dukát, 2004), thus its presence reduces flood conveyance considerably (sándor and kiss, 2007; delai et al., 2017). amorpha fruticosa originates from south-eastern north america, and it was introduced in hungary at the end of the 19 th century in order to stabilize riverbanks and to protect them from intensive erosion (simonkai, 1893; szigetvári and tóth, 2012). the amorpha forms 3-4 m high shrubbery (mihály and botta-dukát, 2004), and according to previous measurements in these very dense shrubbery the flood flow velocity decreases to 0 m/s (sándor and kiss, 2007). former researches were limited to the estimation of vegetation density (chow 1959; barnes 1967; acrement and schneider, 1989), they did not consider the role of invasive species, and they did calculated the influence of different floodplain management methods on flood conveyance, on peak flood levels, and did not model the role of invasive species on increasing flood hazard. the aim of the present study is (1) to determine the long-term land use changes on the floodplain of the lower tisza river, and the effect of these changes on vegetation density; (2) to evaluate the role of the invasive amorpha fruticosa in increasing vegetation density, and finally (3) to calculate the extent of flood level increase caused by the dense floodplain vegetation. the ultimate goal is to model the effect of two floodplain management scenarios on flood conveyance, thus what would happen if amorpha fruticosa was cleared from the floodplain vegetation. the results of two different models (hec-ras and ces) will be compared to evaluate the reliability of the results. study area the tisza river is the second longest river in hungary (length: 962 km, catchment area: 157,200 km2). since the middle of the 19th century the river has been significantly regulated, the formerly 5-10 km wide natural floodplain have been confined by artificial levees, thus today the active floodplain is just 1-4 km wide. some bends have been cut off shortening the tisza river by 457 km (32%). these affected the hydrology ad hydraulics of the river, the slope of the channel and the land-use of the floodplains. the tisza river is characterized by two floods, caused by early spring snow-melt and early summer rainfalls. the mean discharge of the tisza river at szeged gauging station is 810 m3/s (maximum 4,346 m3/s; lászlóffy, 1982). as a result of the regulation works, flood levels have increased by 200-350 cm (rakonczai and kozák, 2009). the duration of floods on the lower tisza river is 54 days/year on average (kiss 2014). since the tisza is a lowland river, its flood can be simultaneous with the floods of the tributaries or of the danube, and they can block each other, thus longlasting ad high floods could develop. the mean water slope of the tisza river is only 2.9 cm/km in the hungarian section (lászlóffy, 1982; kiss, 2014). the bedload is fine sand (9,000 t/year; lászlóffy, 1982), and the river transports a great amount of suspended silt and clay sediment (18.7 t/year; lászlóffy, 1982). the average flow velocity is 0.1-0.15 m/s (kiss, 2014). the changes in vegetation density and flood conveyance were analysed on a 10 km long section (180190 rkm) of the lower tisza river, north from the city of szeged, at algyő. the boundaries of the study area are not the borders of the natural floodplain, but the artificial levees built in the 19th century (fig. 2). the mean channel width is 160 m, while the mean water depth is ca. 14 m, but during floods it could be as much as 19-20 m (lászlóffy, 1982). nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. 5 methods the long-term land-use changes of the study area were analysed since the end of the 18th century, based on 1:28,000 scale maps of historic military surveys (1784, 1861-1864 and 1881-1884), a 1:10,000 scale topographic map (1980s), and google earth image (2017) were used. as a first step, the territory of the different land-use categories was determined on the geo-corrected spatial database. to evaluate the long-term impact of vegetation on surface roughness, the average roughness values (n1-n) determined by chow (1959) were assigned to each landuse category (table 1). then the average vegetation roughness of the study area at a given year (nyear) was weighted by the territory of each land-use category (a1-n): 𝑛𝑦𝑒𝑎𝑟 = (𝐴1×𝑛1)+(𝐴2×𝑛2)+⋯(𝐴𝑛×𝑛𝑛) 100 eq. 1 table 1 applied land-use categories and their mean roughness values (chow, 1959) vegetation roughness category land-use category roughness coefficient n1 wetland 0.017 n2 bare surface 0.018 n3 forest 0.100 n4 meadow, pasture 0.030 n5 meadow, pasture with sparse trees and shrubs 0.050 n6 orchard 0.050 n7 arable land 0.040 n8 artificial surface 0.013 as there are no previous data on the extension and density of the invasive amorpha fruticosa, we mapped its density during the winter of 2017/2018 in three woody land-use categories: in forest plantations, in riparian forests and in abandoned arable lands, meadows and pastures where a. fruticosa has started to spread aggressively. the selected 15 plots represent the three land-use category quite well. to determine vegetation density we used warmink’s (2007) photograph based parallel photographic (pp) method, which could be used to calculate the area occupied by vegetation in a given volume. during the measurements photographs were taken in a quadrate (2 m x 3 m) in front a 2 m high a nd 3 m wide white screen (fig. 3a), thus in a given quadrate the dark stems were well separated from the white background (fig. 3b). after converting the photographs into black and white images (fig. 3c), the area occupied by vegetation in front of the screen was be calculated. inserting these calculated values into equation 2 the vegetation density (dvpp) in each quadrate was calculated (warmink, 2007): 𝐷𝑣𝑃𝑃 = − 1 𝐿 ∗ 𝑙𝑛(1 − 𝐴𝑡𝑜𝑡) eq. 2 where l is the length of the white screen (3 m), and atot is the ratio of black pixels represented by vegetation. the dvpp is a non-dimensional value between 0.0 and 1.0. the vegetation density was calculated for two conditions: representing (1) the actual vegetation with a. fruticosa, and (2) an ideal, well-maintained condition without a. fruticosa. to calculate the latest, the amorpha fruticosa stems were erased from the black and white images (fig. 3d), and then vegetation density was re-calculated using eq. 2. the calculated vegetation density values were used in hec-ras (institute for water resources, u.s. army corps of engineers) and ces (uk environmental agency) models. the aim was to determine how flood conveyance would change in relation with vegetation density. during the modelling, we used the data of the 2006 record high flood (max. height: 1,062 cm; max. discharge: 2,720 m3/s). fig. 2 study area and the location of cross-section used in hec-ras and ces models 6 nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. in hec-ras, during the first run, the actual vegetation density values (n=0.23) were used to model flood levels, with ±10 cm accuracy. in the second run the vegetation density data of “ideal, well-maintained condition without a. fruticosa” was applied in the 10 km long section of the floodplain. this ideal conditions equals to ‘pastures with high grass, cultivated areas with mature row crops, scattered brush, and cleared land with tree stumps and no stumps’, where n=0.035 (chow, 1959). the hydraulic effects of the decreased surface roughness were calculated at three cross-sections, at the upstream end, at the middle and at the downstream end of the 10 km long reach (fig. 2). finally, the temporal and spatial changes of the flood wave were analysed. in the ces model the hydraulic changes also at three cross-sections were analysed, however no temporal analysis could be made, thus the model run just during the peak of the flood. the selected cross-sections were close to the ones in hec-ras (fig. 2), but they were not identical. the surface topography was extracted from the 1:10,000 scale topographic map, while channel topography was provided by the lower tisza district water directorate (ativizig). the ces model – similarly to hec-ras – was run for two scenarios, (1) with the actual vegetation roughness with amorpha, and (2) with ideal conditions without it. results land-use of the floodplain along the lower tisza river has changed considerably in the last two hundred years (fig. 4-5). at the time of the first survey (1784) the conditions refer to almost natural state, as it reflects the environment before the river regulation works and fig. 3 photographs of vegetation were taken from a track in front a whitescreen (3a), then the photos were mosaiced (3b). finally black and white images were used to evaluate the vegetation density with amorha (3c) and without it (3d). fig. 4 land-use changes of the study area since the late 18th century nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. 7 artificial levee constructions. most of the area (92%) was occupied by wetlands, where water covered the area almost permanently. the proportion of forests was only 5%, and their patches grow along the channel, where the overbank aggradation created higher surfaces. in the mid19th century channel regulation works started. by the time of the second survey (1861-1864) two meanders were already cut off in the upstream part of the study area, though the third one in south was still untouched. therefore, the artificial levee system at that time was not located at the same place as the present-day system. the proportion of wetlands decreased drastically (22%), and they were replaced by meadows and pastures (56%). the forests expanded moderately (9%), but they were still located along the riverbanks. longer flood-free periods enabled some areas to be cultivated (proportion of arable lands: 7%). two decades later (1881-1884) most of the wetlands had already disappeared (2%). almost the whole study area was occupied by meadows and pastures (94%), but almost on half of their area trees started to grow. in contrast, the proportion of forests had decreased to 2%. one hundred years later (1980s) the vegetation cover of the study area had changed considerably, as the area of pastures and meadows became afforested, therefore their proportion decreased to 11%. because of extensive poplar plantations, the proportion of forests increased to 78%. nowadays (2017) the forested area of the floodplain increased further on (86%). only some arable lands and grasslands remained (8%), however, according to our field survey three fourth of them have been abandoned and they are densely covered by amorpha fruticosa. fig. 5 proportional changes of land use-categories since the late 18th century. i: 1784; ii: 1861-64; iii: 1881-84; iv: 1979-85; v: 2017; a: water surface; b: wetland; c: bare surface; d: forest; e: meadow and pasture; f: meadow and pasture with sparse trees and shrubs; g: orchard; h: arable land; i: artificial surface roughness values defined in the literature weighted by the proportion of land-use categories (see table 1) reflect that the vegetation roughness of the floodplain has been increased since the late 18th century (fig. 6). the vegetation roughness increased especially in the 1980s due to forest plantations, and nowadays because of the presence of amorpha fruticosa. overall, the mean vegetation roughness of the study area has increased from n=0.021 to n=0.14, thus it increased by seven times since the late 18th century. fig. 6 mean vegetation roughness of the study area based on land-use categories (1784-2017) and on pp-method (2018) the role of amorpha fruticosa in increasing vegetation density: results of parallel photographic method in the study area three woody vegetation types were identified and studied in detail. at present, riparian forests cover 71% of the study area. due to the shading effect of the older trees, the abundance of amorpha fruticosa is the smallest in these forests. therefore, the invasive species increases vegetation density only by 3% on average (010%), depending on the amount of sunlight reaching the surface and the rate of disturbance. in these almost natural riparian forests the vegetation roughness is 0.13 on average (min: 0.06, max: 0.22), but without amorpha fruticosa it would be 0.12. forest plantations occupy 15% of the floodplain, with trees of different age. generally, in the first years after the plantations the undergrowth vegetation is managed to support the growth of the trees, but when the poplars grow above 3-4 m, the undergrowth is not managed any longer. since the coverage of the foliage of planted forests is less closed, more sunlight could reach the surface, therefore older plantations, depending on the lack of management, could be invaded by non-native species. in the study area, amorpha fruticosa increases vegetation density by 23% on average. the vegetation roughness of these forests is 0.10 (min: 0.07, max: 0.15), while without a. fruticosa vegetation roughness would decrease to 0.08. in the floodplain of the lower tisza river amorpha fruticosa increases vegetation density by the greatest degree on abandoned arable lands, meadows and pastures. the abandonment of these areas accelerated after the flood in 2006, when the floodplain was covered by ca. 6-8 m height water column for one week, and the inundation itself lasted for 104 days (kiss 2014). this high and long flood destroyed the agricultural crops and destroyed some of the natural undergrowth. in addition, the flood period had started in 1998; therefore, farmers gave up cultivating these floodplain lands because of the returning annual loss. on these abandoned lands amorpha fruticosa increases the vegetation density by up to 100%, but in less invaded areas it contributes to vegetation density by 76% on average (min. 50%). due to the presence of a. fruticosa the average vegetation density of abandoned lands is 0.12 (min: 0.09, max: 0.16), while without invasive species this value would be only 0.03. 8 nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. flood conveyance as a function of vegetation: results of hec-ras and ces modelling the results of the two scenarios (unmanaged floodplain with n=0.23, and managed floodplain with n=0.035) run in hec-ras model suggest that the most significant changes in water levels appeared in the upstream crosssection (191.82 rkm; fig. 7) of the 10 km-long study reach. in case of the no. 2 scenario the vegetation of the 10 km-long floodplain section is managed (cleared from amorpha), thus the floodplain vegetation creates fewer obstacles (resistance) against flood flow. therefore, the velocity of the flood is accelerated. in this case, the peak flood level decreases by 15 cm compared to the “unmanaged” scenario (n=0.035). the greatest difference between the hydrographs was 18 cm in the falling limb of the floodwave. at the downstream cross-section (182.95 rkm) of the modelled 10 km-long reach, the processes are different from those of the upstream cross-section (fig. 8). in the no.2. scenario this cross-section is located at the downstream end of the managed section, at the border between the managed and unmanaged vegetation (n=0.23). thus the flood flow collides with the dense vegetation, and forced to flow through it. the resistance is combined with the small slope of the river and the backwater effect of the danube. though the flood peaks of the two scenarios slightly differ (±1-2 cm), during the falling stage the differences in stages increases (6 cm), though it is within the error of the model (±10 cm). the cross-section (189.00 rkm) located in the middle of the study area is in the middle of the managed floodplain section in case of no.2. scenario. here the processes described at the upstream and downstream cross-sections are combined (fig. 9). water level changes are similar to the ones at the upstream cross-section, but the peak water level decreases just by 6 cm in no.2. scenario. the greatest difference (9 cm) between the hydrographs was detected also in the falling limb of the flood. fig. 7. changes in water level at the upstream cross-section of the 10 km-long studied floodplain. the model was calibrated to the 2006 flood. the hydrograph of the no. 1. scenario (blue line) refers to the actual situation with unmanaged floodplain vegetation, while the no. 2. scenario refers to managed vegetation cover (red line) fig 8 changes in water level at the downstream cross-section of the 10 km-long studied floodplain. the model was calibrated to the 2006 flood. the hydrograph of the no. 1. scenario (blue line) refers to the actual situation with unmanaged floodplain vegetation, while the no. 2. scenario refers to managed vegetation cover (red line) nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. 9 the temporal differences in hydrographs are the greatest in the falling limb of the flood wave. it could be explained by the characteristic of the flood: the modelled 2006 flood has been the highest on the tisza river and its peak lasted nearly for a week. this special characteristic was caused by back-water effect of the danube, thus the flood wave of the tisza river could fall just after the flood on the danube had passed. thus, the impoundment and the reduced flow velocity was just partly caused by the vegetation, but probably it was surpassed by the impounding effect of the danube, therefore the effect of vegetation roughness on flood flow could only became obvious in the falling limb of the flood wave, when the danube had no longer had significant effect on the tisza river. the ces model gave similar result to the hecras model (table 2; fig. 10). the results of the three cross-sections slightly differed, because the rate of invasion by amorpha fruticosa varied and the width of the floodplain was different too. at all three cross sections amorpha fruticosa contributed to vegetation density by the same rate (dvpp increased by 0.03). because of the presence of amorpha fruticosa the peak discharge of the flood resulted in higher water stage by 15.3 cm at the upstream and downstream crosssections, while it was only 12 cm at the middle cross section. based in the ces model calculations the presence of amorpha fruticosa decreased the mean flow velocity by 0.016 m/s. there is a slight difference in the decrease of discharge at a given (highest) water stage: at the upstream cross-section the discharge of the peak stage was decreased by 5.7% by the presence of the a. fruticosa, while at the downstream cross-section it was decreased by 6% respectively. the difference could originate from the floodplain width, as the floodplain is wider along the downstream section (770 m) than upstream (680 m). at the middle cross-section the invasive species decreased the mean flow velocity by 0.014 m/s, reduced the discharge of the peak stage by 4 %, and resulted in higher water stage by 12.1 cm of the same peak discharge. discussion in the present study we analysed the changes of vegetation cover on the floodplain of the lower tisza river, determined the role of the invasive amorpha fruticosa in increasing the vegetation density of the floodplain, and modelled its role in reducing flood conveyance. long-term changes (1784-2017) of land-use on the floodplain of the lower tisza river suggest that at the end of the 18th century, before the river engineering works, most of the surface was covered by wetlands (92%). as a result of 19th century river regulation works the channel fig 9 changes in water level at the middle cross-section of the 10 km-long studied floodplain. the model was calibrated to the 2006 flood. the hydrograph of the no. 1. scenario (blue line) refers to the actual situation with unmanaged floodplain vegetation, while the no. 2. scenario refers to mana ged vegetation cover (red line) table 2 main characteristics of the studied cross-sections, and the drop of water stages on case of managed floodplain, thus the clearance of amorpha fruticosa (a.f.). hecpeak: during the peak flood modelled by hec -ras, hecfall: during the falling stage of the flood modelled by hec-ras, ces: during the peak of the flood modelled by ces floodplain with (m) channel slope (cm/km) land-use (%) vegetation roughness (dvpp) decrease in water levels (clearing a.f.) crosssection (rkm) forest meadow, pasture with a.f. without a.f. hec peak hec fall ces 189.5 680 4 100 0 0.13 0.10 15 18 15 187.8 750 4 100 0 0.13 0.10 6 9 12 181.7 770 4 61 23 0.13 0.07 0 6 15 10 nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. incised, thus low water stages decreased (by 260-280 cm; lászlóffy, 1982), which resulted in drier floodplain surfaces. therefore, since the mid-19th century the wetlands were replaced by meadows and pastures (94%), and riparian forests (9%). nowadays, most of the floodplain is covered by natural or planted forests (86%), while the proportion of meadows decreased to 2%. the vegetation roughness of the study area has increased fourfold since the late-18th century. this increased vegetation roughness has a significant impact on flood conveyance. since similar land-use changes were observed on other floodplain areas of hungary (gábris et al., 2004; sándor and kiss, 2008; oroszi and kiss, 2006), it could be assumed that the vegetation has influenced hydrological conditions in a similar way. however, the actual surface roughness is greater (0.14) than it was calculated from the land-use categories, due to the presence of invasive species, and because in the literature the impact of invasive species on vegetation density was not considered. most of the meadows, pastures and arable lands are strongly invaded by amorpha fruticosa, therefore 8% of floodplain surfaces are covered exclusively by a. fruticosa, but it has spread in riparian and planted forests as well. results of vegetation density calculations were used in hec-ras and ces models, to determine the role of two different floodplain management methods on flood conveyance. in the no.1. scenario the actual vegetation density (with amorpha fruticosa) was applied, while in the no.2. scenario the amorpha was cleared from the area, thus the floodplain vegetation was managed. the comparison of the two scenarios in hec-ras suggests that if the floodplain was managed properly and it was cleared from amorpha fruticosa on the studied 10 km long reach of the river, at the upstream section water flow would accelerate because of reduced surface roughness, which would decrease water levels. therefore, the level of the peak flood could be reduced by 15 cm according to the hec-ras and by 12-15 cm according to the ces. the downstream section of the managed floodplain is followed by an unmanaged area, therefore, its increasing vegetation roughness could decrease the flood conveyance and flow velocity by impounding the flood, thus at this section higher peak levels could occur (but it was under the error limit of the model). at the middle section the effects described above (i.e. increased and decreased flood conveyance) combined, therefore here the flood conveyance would be just slightly better, thus the drop of peak flood level is moderate (9 cm). conclusion in the present study, we analysed vegetation density and its effects on flood conveyance with different methods. the parallel photographic (pp) method was used to calculate the actual vegetation density in different landuse categories. the resulted vegetation roughness values are 1.5-fold higher than values given in the literature for the given land-use category. this can be explained by the very dense population of invasive species, since these species were not taken into account in the vegetation roughness values defined in the literature (chow 1959), they gave only empirical values for natural vegetation cover. with the pp method, however, the vegetation density could only be measured in a small quadrate (6 m2) and up to a height of 2 m; although during floods the floodplain is inundated by 6-8 m high water column. further disadvantages of the pp method are low time efficiency and errors occurring during taking the photographs. in sunshine, the shadows of the stems and branches can modify the ratio of black and white pixels, the white screen can lean in wind, and the snow cover on the branches (since photographs were taken in winter) can also modify the number of black pixels. during photo fig. 10 results of the ces modelling at the downstream cross-section (181.7 rkm). a) discharge change at a given water level (from the lowest point of the channel bed) in the case of vegetation with and without amorpha fruticosa; b) decrease in discharge on the floodplain due to the presence of amorpha fruticosa; and c) land-use categories along the cross-section nagy et al. 2018 / journal of environmental geography 11 (3–4), 3–12. 11 processing errors can occur when the non-vertical stems are photographed from different angles, therefore after the photos are assembled these stems can appear several times on the photos. based on our experience, however, these errors do not cause significant differences in the results. flood conveyance was analyzed in two hydraulic models. the advantage of the hec-ras model is that a real flood event could be modelled, and the spatial and temporal effects of various floodplain vegetation on flood conveyance could be analysed. disadvantage of the model is that its setting up is time and data consuming. besides, the characteristics and roughness values of the floodplain and of the channel, the hydrographs of a particular flood event are also needed along a long river reach (in our case it was 200 km) to keep the model stable. great advantage of ces model is that it is very easy to use, and it does not require large amount of input data. the hydrological processes on the floodplain, however, could be analysed only at during the flood peak and along one section, thus temporal and spatial changes in the processes could not be studied. accordingly, the selection the most suitable cross-section on the floodplain is very important. from the point of view of floodplain management it can be stated that by adequate vegetation management (i.e. removing invasive species, restoration of land-use with lower surface roughness) of longer floodplain sections flood stages could be decreased. the length of the managed area, however, may vary depending on the slope of the floodplain and the areal extension of impounded flow, since in short managed sections the effect of impoundment may distinguish the effect of better flood conveyance. accordingly, clearing vegetation in patches would not have any detectable effect on flow conditions. the analysis, however, should be repeated on floodplain sections with different hydrological conditions, since the effect of vegetation on flood conveyance may vary based on slope, floodplain width and flood characteristics. overall, reducing vegetation roughness coefficient by properly managing floodplains would have a positive impact on flood hazard, since flood waves would accelerate and peak flood stages would decrease. acknowledgements we would like to thank the lower tisza district water directorate for data for the models. the research was supported by wwf hungary and the hungarian research found (otka 119 193). references acrement, g.j., schneider, v.r. 1989. roughness coefficients for densely vegetated flood plains. u. s. geological survey, waterresources investigations report 83–4247. doi: 10.3133/wri834247 antonarakis, a.s., richards, k.s., 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(ed.) aradvármegye és arad szabad királyi város monographiája i., arad, 426 p. szigetvári, cs., tóth, t. 2012. cserjés gyalogakác (amorpha shrubs). in: csiszár, á. (ed.) inváziós növényfajok magyarországon, nyugat-magyarországi egyetem kiadó, 121–126. takuya, u., keiichi, k., kohji, m. 2014. experimental and numerical study on hydrodynamics of riparian vegetation. journal of hydrodynamics 26(5), 796–806. doi: 10.1016/s10016058(14)60088-3 vargas-luna, a., crosato, a., uijttewaal, w.s.j. 2015. effects of vegetation on flow and sediment transport: comparative analyses and validation of predicting models. earth surf. process. landforms 40, 157–176. doi: 10.1002/esp.3633 wang, c., zheng, s., wang, p., hou, j. 2015. interactions between vegetation, water flow and sediment transport: a review. journal of hydrodynamics 27(1), 24–37. doi: 10.1016/s10016058(15)60453-x warmink, j.j. 2007. vegetation density measurements using parallel photography and terrestrial laser scanning. master thesis, utrecht university, utrecht, the netherlands, 83 p. introduction study area methods results the role of amorpha fruticosa in increasing vegetation density: results of parallel photographic method flood conveyance as a function of vegetation: results of hec-ras and ces modelling discussion conclusion acknowledgements references journal of environmental geography 5 (1–2), 29–38. reconstruction of palaeo-hydrology and fluvial architecture at the orosháza palaeo-channel of river maros, hungary orsolya katona 1* , györgy sipos 1 , alexandru onaca 2 , florina ardelean 2 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 1 department of geography, west university of timisoara, v. parvan str. 4, timisoara, ro-300223, romania *corresponding author, e-mail: orsi1983@gmail.com abstract several studies have addressed the impact of climate change and tectonic activity on fluvial systems. when investigating these systems palaeo-hydrological and geomorphological data on abandoned channels can yield valuable results. the main aim of our work was to reconstruct morphological conditions at the orosháza palaeo-channel and to estimate the bankfull discharge which characterized the channel during its formation. there are several equations predicting bankfull discharge on the basis of planform parameters, but these only work for meandering rivers. in case of braided channels flow reconstruction can only be made by using cross-sectional parameters. the orosháza palaeo-channel provided the means of a comparative analysis in this respect. by a sudden pattern change both meandering and braided reaches, supposedly having a very similar bankfull discharge, could be simultaneously studied. planform parameters and present cross-sections were determined on the basis of a high resolution dem, while original cross-section parameters were assessed using sedimentological and geophysical methods. based on sedimentological data, channel pattern transition was mainly driven by intensive bedload accumulation at the edge of the maros alluvial fan (maf). slope differences could not be evened out due to an avulsion close to the apex of the fan. concerning discharge calculations a good agreement was found between a region-specific planform based equation and the cross-section based grauckler-manning equation. values determined for the braided and meandering reach were also in a good correspondence. consequently, the presented approach is suitable to determine the discharge of other braided palaeo-channels on the maf and elsewhere. keywords: morphological reconstruction, hydrological reconstruction, sedimentology, geophysics, discharge equations introduction the reconstruction of fluvial systems is of key importance if the climatic variations or tectonic development of an area is investigated. therefore in the past decades numerous studies have been made to investigate past fluvial architecture, morphology and sedimentology at various locations (e.g. dury, 1976; sridhar, 2007; timár and gábris, 2008). when studying ancient fluvial systems one of the basic approaches is to allocate and investigate abandoned channels still detectable on the surface. these provide information primarily on late pleistocene and holocene changes in the environment (carlston, 1965; bridge, 2003). based on the morphometry and sedimentary structure of these channels various conclusions can be made on the discharge of the forming river and the quality and quantity of its sediment. these in turn might provide information to the development of contemporary topography and palaeo-climatic conditions. the interpretation of surficial and shallow deposits is either based on in situ observations, laboratory experiments or geophysical methods (bridge, 2003; sridhar, 2007). the fluvial network of the pannonian basin has been affected in the past by climate variations and different rate of tectonic subsidence and uplift processes, the effect of base level change can be regarded negligible (bridge, 2003; timár et al., 2005; gábris and nádor 2007; nádor et al. 2007). tectonic processes are primarily important in determining the gradient and the direction of the flow of rivers (bridge, 2003; laure, 2008). as the tectonic development of the pannonian basin has been very complex, the reconstruction of the changes in the fluvial network since the regression of the pannonian lake still poses some questions (gábris et al., 1986) in case of the maros river system as well (mike, 1991). climatic factors, such as mean annual temperature and annual precipitation have an influence on channel pattern by determining runoff the type of weathering and vegetation cover (schumm, 1985; mackey, 1993; bridge, 2003). in the temperate zone the dimensions of a fluvial system is usually adjusted to annually or biannually returning floods, however under changing climatic conditions the role of single, extreme events may be much more significant (schumm, 1985; bridge, 2003). nevertheless, in terms of alluvial rivers the role of bankfull discharge is stressed as channel forming processes are related mostly to these in various works (leopold and wolman, 1957; richards, 1982; schumm, 1985; bridge, 2003). in the pannonian basin, located in a climatic transition zone, variations could be significant in the past and could result tremendous changes in the dimensions and capacity of lowland rivers (gabris, 1986). however, climate change and tectonic activity can be equally apparent and it is particularly difficult to know if a sedimentological and morphological change is due to which of the above controlling factors. (krzyszkowski, 1996; bridge, 2003; vanderberghe, 2003). recent activity in data collection on present day rivers has allowed on many parts of the world to develop equations which can be applied to reconstruct past discharge values (bridge, 2003). the relationship between discharge and planform parameters is well demonstrated in case of meandering rivers (williams, 30 katona et al. (2012) 1984; bridge, 2003). parameters mostly used for the reconstruction are chord length, radius of meander and wavelength of meandering (williams, 1984). these parameters are sometimes not easy to assess, due to the low number of detectable palaeo-channels, or blurred morphology. discharge calculations of this type obviously will not work on straight or braided rivers. another approach for determining discharge is the application of hydraulic parameters, such as area of cross-section, slope, grain size and roughness. relationships of this type are more or less based on the classical equation determined by gauckler and manning (1890s). the gauckler-manning equation has been reworked by several authors to fit to different channel patterns and different sets of empirical data (lane, 1957; leopold and wolman, 1957; osterkamp, 1978; begin, 1981), however the original equation is still widely used in the literature (bridge, 2003). when applying hydraulic parameters for the discharge calculations of palaeo-channels it is of major concern to determine values of original slope and cross-sectional area. in these investigations the role of topographical and sedimentological measurements is inevitable, however shallow geophysical methods, such as ground penetrating radar (gpr), or electrical resistance tomography (ert) can be also efficient if environmental conditions are suitable (gourrya et al., 2003; carreonfreyer et al., 2003; bersezio et al., 2007; van dam, 2010; yadav et al., 2010; rucker et al., 2011) considering the above, the first aim of our study was to test morphological and hydraulical equations on a braided and meandering palaeo-channel section located on the alluvial fan of the maros river in hungary. for the calculations planimetric, topographic, sedimentological and geophysical data were applied. henceforth the potential of different geophysical met hods could be assessed. finally, we aimed to calculate an average bankfull, or channel forming discharge, characterising the investigated palaeo-channel reach. study area the study area is located on the interfluve area bordered by the tisza, maros and körös rivers. geomorphologically, the territory is primarily dominated by the alluvial fan of the maros river (pécsi, 1959). the maros alluvial fan (maf) with a total area of 10 000 km 2 hosts numerous palaeo-channels, representing late glacial, holocene river generations of the maros (borsy, 1989; molnár, 2007; sipos et al., 2012). from these, one of the largest palaeo-channel is located in the axis of the alluvial fan, near its western edge at the town of orosháza (fig. 1). the present day catchment of the river is 30 000 km 2 , most of which is located in the transylvanian basin, the eastern and southern carpathians (molnár, 2007). there are no signs for significant changes in the size of the upland catchment during the quaternary (mike, 1991). on its lowland reach the maros has built a large alluvial fan during the late pliocene and pleistocene with a radius of 80-100 km starting from the lipova gorge. changes in the direction of its flow on the fan were caused partly by tectonic (local uplifts and subsidences) and geomorphological (avulsion) factors (borsy, 1989). the apex of the fan is at 130 m asl while its rim is between 80-85 m asl. the slope of the fan is not uniform, usually it is between 20 and 30 cm/km however near the edge there is a belt where it can reach occasionally 50 cm/km (sümeghy and kiss, 2011). thanked to the above, the river has a relatively high energy which is also resembled by the high sediment transport capacity of the present-day maros, which is similar to that of the tisza or the danube. horizontally, the sediment of the maf changes from primarily gravel near the apex to sand and silt towards the edges (borsy, 1989). vertical variations in the granulometry of the fan sediment are related to pleistocene climatic changes in general, namely coarser and finer strata referring to glacial and interglacial phases, respectively (mike, 1991; molnár, 2007). the hungarian part of the maf can be divided into four geomorphological subunits based on surface forms and sediments (pécsi, 1959). the central part is covered by sandy loess and dominated by meandering palaeochannels (fig. 1). the ne wing is mainly composed of alluvial loess and silt deposits and hosts both meandering and braided palaeo-channels. the northern edge just south of the körös basin is covered with sandy loess and primarily braided channel forms are characteristic. finally the western wing has alluvial loess on the surface and meandering channels. the site of the investigation at orosháza is right at the edge of the alluvial fan. east of the town the almost 1 km wide channel has a braided pattern with several sub channels and huge bar forms. downstream the same channel after leaving the edge of the fan becomes meandering, its width decreases at certain sections to only a few 100 m. according to results of osl dating the orosháza channel was active during the pleistocene holocene shift, between 14 and 8 ka (sipos et al., 2012). as a consequence, post formational loess deposition could not be significant. partly because of this and due to supposedly fast avulsion processes (sümeghy and kiss, 2011) forms are still sharp and well detectable. for the present research two study sites were investigated, one on the braided, the other on the meandering section of the palaeo-channel (fig. 1). reconstruction of palaeo-hydrology and fluvial architecture at the orosháza palaeo-channel of river maros, hungary 31 fig. 1 location of the study area and the geomorphological map of the region (based on pécsi, 2000) 32 katona et al. (2012) methods as a first step a digital elevation model (dem) was produced from 1:10000 scale topographic maps with 1 m interval primary contour lines, supplemented by 0.5 m interval secondary contour lines on flat areas. the dem was made with the arcgis topo to raster interpolation tool. vertical resolution was better than 1 m, while horizontal raster resolution was 10 m (fig. 2). the dem was used to determine channel planimetric parameters (meander wavelength, meander radius), present day silted up cross-sectional parameters (width, deth, area), and channel slope conditions on the investigated palaeo-reach. cross-sectional indicators were measured at various points in order to get average parameters. the area’s general slope was calculated on the basis of srtm data. since the dem enabled only the calculation of modified, silted up cross-sectional parameters other methods also had to be applied and compared to determine the original dimensions of the river. the primary aim was to determine the depth of channel sediments and calculate the true depth of the river. in all 16 drillings were made in two cross-sections representing both the braided and the meandering reaches (fig. 2). drillings were representing characteristic topographic features, such as the natural levee, river bed, bar crests, point bars and chutes. bore holes were deepened till the level of the groundwater. the depth of the drillings in the channel was 1.5-2 m, on point bars and levees 5-6 m. samples were taken at every 10 cm. sedimentological analysis included grainsize analysis. the grainsize-distribution of the samples was determined by a fritsch analysette 22 laser equipment with a measurement range of 0.08-2000 μm. samples underwent ultrasonic homogenisation and all measurements were repeated three times to check if there is further disintegration. for the geomorphological interpretation sample d50 values were determined. in order to test the applicability of geophysical methods in determining sedimentary shifts gpr and ert were applied in the drilling sections (fig. 3). gpr measurements were made with a gssi type instrument, using 200 and 270 mhz shielded antennae. unfortunately right during the first field work it turned out that sedimentary conditions (high clay and silt content in the upper strata) disable the successful use of gpr technology on these sites. therefore, ert profiling was favoured during later measurements. for these measurements a pasi type 32 electrode system was used. ert sections were measured using a wenner electrode array. electrode spacing was 5 m, one section fig. 2 dem generated from 1:10000 scale topographic maps with the cross-sections studied in detail reconstruction of palaeo-hydrology and fluvial architecture at the orosháza palaeo-channel of river maros, hungary 33 was therefore 160 m, from these 5 were measured on both sites. neighbouring sections had a 50 % overlap. maximum penetration was 20-30 m, data were collected from 10 levels. from a geomorphological aspect bankfull discharge is one of the most important parameter of river flows, as it is highly responsible for the geometry of the crosssections and the channel pattern as well (schumm, 1985). bankfull discharge was assessed by selecting and using equations from the literature, with special attention to the range of applicability of the published formulae. in terms of planimetric parameters the equations of leopold and wolman (1957) and mackey (1993) were selected (table 1). these formulae can be applied only for meandering channels, and they use meander wavelength as the base parameter. the relevance and significance of meander wavelength was also reinforced by timár and gábris (2008) when studying the channels of the great hungarian plain. the selected formulae operate up till the 1000 m 3 /s discharge range, thus proved to be adequate as a first approximation. discharge calculations were also made from crosssectional parameters. at the two measurement sites these were derived from dem (present) and sedimentological (original) analyses, results were compared and coefficients were calculated. these coefficients were used to calculate average original cross-section parameters from representative present-day values calculated by taking the mean and standard deviation of several measurements on the dem. in case of the meandering section the relationships determined by dury (1976) and williams (1978) were tested. the range of the applicability of the williams (1978) formula (0.5<qb<28320m 3 /s; 0.7<ab<8510m 2 ; 0,000041<s<0,081) is well over the expected discharge of the investigated system (table 1). in terms of the braided reach the modified gauckler-manning equation was applied. the basic equation (q=ar 2/3 s 1/2 /n) was modified and reduced by rotnicki (1983) based on more than 1000 observations on rivers with highly variable geometry (q=(1,49/n)wd 5/3 sc 1/2 ). parameter “n” was determined after goodwill and sleigh (2002), and calculations made on the basis of present-day measurements on river maros (katona et al., 2012). the average value used for calculations was 0.056. results sedimentological and geomorphological interpretation the original channel cross-sections were reconstructed on the basis of sedimentological data and geophysical measurements. channel sediments can be clearly identified in the sedimentary columns, thus the amount of silting up in the thalweg zone can be est imated to be approximately 2-3 m (fig. 4). silting up is suggested to be the result of post-formational fluvial activity as from time to time the channel could be partially reactivated during the extreme floods of the fig. 3 geophysical field investigations. the bank of the braided section on the left, and bank of meandering on the right. table 1 equations applied for the calculation of bankfull discharge meandering author equation planform leopold and wolman (1957) l=65.2qb 0,5 mackey (1993) l=72.16qb 0,49 sümeghy and kiss (2011) q = 0.0003*l 2 +0.3440*l-81.329 cross-section dury (1976) qb=9.93 ab 0,85 williams (1978) qb=4.0ab 1,21 sc 0,28 braided author equation cross-section grauckler-manning q=wd 5/3 sc 1/2 *1.49/n 34 katona et al. (2012) maros system. natural levees, point bars and mid channel bars are still sharply detectable. we took the present level of these as the minimum heights of banks as subsequent erosion and agricultural activity could lower their level. the d50 value of overbank, or suspended sediments is similar at the two study sites, being 25-30 and 20-25 μm in the braided and the meandering corss-section, respectively (fig. 4). nevertheless, there is an abrupt change in the grainsize of the bedload. on the braided section the d50 value of channel sediments is 200-300 μm, representing the range of coarse grain sand. meanwhile, less than 15 km downstream on the meandering section, mean grainsize decrease to 50-150 μm. the degree of sorting however also decreases, but this is due to the appearance of clayey fractions in channel sediments. in terms of channel slope and general slope it turns obvious that the upstream braided section has a 15-20 % lower slope than the downstream meandering one (table 2). the knick point signs the transition between channel patterns. such change in slope is unusual in terms of normal gradient alluvial rivers (e.g. schumm, 1985; richards, 1996). in this case a possible cause could be tectonic activity, however, this does not explain the significant change in the composition of channel sediments. pattern and slope change is rather caused by the geomorphological background, i.e. the knick point marks the edge of the alluvial fan. fig. 4 cross-section of the sites with sedimentary sequences of drillings and generalised ert profiles reconstruction of palaeo-hydrology and fluvial architecture at the orosháza palaeo-channel of river maros, hungary 35 by reaching the distal parts of the fan the competence and capacity of the river, having a very high bed load of coarse sand, decreased considerably, leading to the development of an aggradation zone (braided section). downstream of this zone slope and energy increased, and as the river already deposited its coarse sediment upstream, meandering was favoured. meandering could be further facilitated by sedimentological differences, i.e. in front of the coarser alluvial fan sediments finer more cohesive floodplain deposits are located, confining the banks of the channel (fig. 1 and 4). difference in slope suggests a difference in crosssections as well, namely, larger slope means smaller cross-section at similar discharge on the same river. data have reinforced this relationship (table 2). the average cross-section of the braided and meandering reaches could be around 3000 and 3800 m 2 , respectively. width/depth ratios also show a remarkable difference between the two sections, being around 400 on the braided and 130 on the meandering section. geophysical interpretation in an alluvial setting the electric resistance threshold between sedimentary units is hard to determine, as different sediments can have very similar resistance (reynolds, 1997). in general however, the coarser and drier the sediment the higher resistance is received. the study area is primarily characterised by mixed silt, fine and medium sand, which made the interpretation of ert profiles complicated. the ert measurements were made in autumn among dry conditions, thus precipitation could not influence resistivity parameters near the surface (reynolds, 1997). the received values were between 0 and 300 ωm. as a first approximation the threshold between silt and sandy sediments was based on the values reported by nádor et al. (2005) and yadav et al. 2010, and was taken 20 ωm. resistivity profiles however could not entirely be compared to the drilling profiles, due to the resolution provided by the 5m electrode spacing. nevertheless, in case of site 1 (fig. 5) the top layers, especially near the bank of the channel, were dominated by sediments with high resistance down till 10-15 m (75-80 m asl). note that ground water appeared at around 85 m asl, therefore the change experienced in this case is primarily due to changes in grainsize, meaning that coarser sandy sediments are deposited on finer clayey deposits. high resistivity strata wedge out towards the centre of the channel. at site 2 resistivity values were a little higher in general (fig. 6), which seems to contradict the hypothesis that sedimentary deposits are finer in front of the alluvial fan. contradiction can only be relieved if we suggest that the mineral composition of sediments at the two sites is slightly different. this hypotheses however needs further testing. nevertheless, relative differences of the site 2 profile show an opposite pattern than that of site 1 profile. lower than 20 ωm values appear on the top left, while higher resistivity values characterise sediments 5-10 m below the surface. as the boundary is again beneath the ground water table it is obvious that palaeo-channel sediments were laid on coarser deposits. lateral bar surfaces in the middle of the cross section have higher resistivity similar to point bar sediments on the right (fig. 6). based on these data, the boundary surface might represent the base of the palaeo-channel, although the 20 ωm threshold needs to be revised in light of higher resolution ert results. in all, further calculations were based on the results yielded by sedimentological analysis, at present resistivity profiles are not precise enough to draw unambiguous sedimentary boundaries. palaeo-discharge calculations bankfull discharges calculated by different approaches showed considerable variance (table 3). in terms of the meandering reach discharges calculated on the basis of table 2 cross-sectional parameters of the investigated sites site 1 (braided) site 2 (meandering) l (m) 2500 ± 600 s (cm/km) 25.6 ±1.3 29.7 ± 1.0 sc (cm/km) 20.3 ± 0.3 22.5 ± 1.0 parameters of the investigated cross-sections dem drilling coeff. dem drilling coeff. w (m) 1125 1125 1,00 685 685 1.00 d (m) 2,3 2,8 1,21 3,15 4,20 1.33 ab (m 2 ) 2345 3150 1,34 2076 2870 1.38 average values based on several measurements on the dem dem original dem original average w (m) 1120 ± 140 1120 ± 140 595±80 595±80 average d (m) 2,2±0,32 2,7 ± 0,7 3,05±0,7 4,05±0,9 average ab (m 2 ) 2465±470 3025 ± 870 1815±480 2410±625 l: meander wavelength, s: general slope, sc: channel slope, w: width, d: deep, ab: area of bankfull cross section 36 katona et al. (2012) the classical planform equations (leopold and wolman, 1957; mackey 1978) were considerably, almost 50 % lower than the value received using the region-specific formula of sümeghy and kiss (2011). by using the equation of dury (1976), setting up a relationship between discharge and cross-sectional area in case of meandering rivers, the received result was clearly and significantly overshooting the previous values. when slope was introduced to the relationship (williams, 1978) the estimated discharge decreased, but it was still significantly higher than the values derived from planform parameters. by applying the modified gauckler-manning equation the calculated discharge was very close to the results yielded by the sümeghy and kiss formula. based on this, we assume that the two approaches reinforce each other and the bankfull discharge of the river on the meandering section was approximately 2500 m 3 /s. in case of the braided section the only way to determine bankfull discharge was to use the gaucklermanning equation. in theory the result received for this section should be similar to that calculated for the meandering reach. as a matter of fact, results were fairly well corresponding, fell within the error limits and there was only a 9 % difference between the mean values. consequently, the gauckler-manning equation seems to be suitable to determine bankfull discharge values on braided channel section on the maf. it has been proved however that classical planform formulae significantly underestimate, while cross-section based formulae overestimate the discharges in this environment. one reason can be, that based on width/depth ratios the channels – even those meandering – of the maf are transitional. if we compare the received values to the presentday bankfull discharge (850 m 3 /s) of the maros river (fiala et al., 2007), there is a considerable difference, referring to a much different flow regime during the onset of the holocene. table 3 bankfull discharge values calculated from planform and original cross-sectional parameters. equation site 1 site 2 leopold and wolman (1957) 1470 ± 350 m 3 /s mackey (1993) 1390 ± 330 m 3 /s sümeghy and kiss (2011) 2650 ± 630 m 3 /s dury (1976) 7280 ± 1980 m 3 /s williams (1978) 4570 ± 1240 m 3 /s gauckler manning 2220 ± 640 m 3 /s 2445 ± 645 m 3 /s conclusions the orosháza palaeo-channel system provided a good opportunity to test different field and computational methods for determining the bankfull discharge of meandering and braided channel sections. the complex analysis included geomorphological, geophysical and sedimentological methods, and emphasizes the necessity of comparing these results. based on the investigations some important geomorphological results could be drawn. first, a discrepancy between slope and channel pattern was experienced on the area, which is probably due to inherited slope conditions and high bed load deposition near the edge of the maf. this suggests that as a matter of an avulsion event the studied channel was not operating as a main flow path for a long time, i.e. channel slopes could not be adjusted to different general slope values. since their formation the channel silted up 2-3 m, meaning that the forms studied are fairly young, thus the effect of post formational tectonic changes might be also of secondary importance. at the present phase of research sedimentological and geophysical profiles could not entirely be over fig. 5. ert profiles at site 1 fig. 6. ert profiles at site 2 reconstruction of palaeo-hydrology and fluvial architecture at the orosháza palaeo-channel of river maros, hungary 37 lapped, as a matter of their different vertical extent and resolution. however, ert profiling seems to have a great potential in the fast detection of sedimentary structures on the study area if electrode spacing is decreased. gpr measurements failed due to the high clay and silt content of the sediments. discharge calculations on the meandering and braided reaches showed an acceptable agreement. in case of the meandering reach the results based on the meander wavelength/bankfull discharge formula of sümeghy and kiss (2011) and those derived from the gaucklermanning equation reinforced each other. moreover, the value received for the braided reach was also in a good correspondence, meaning that cross-sectional parameters determined from sedimentological results can have an important role in estimating the bankfull discharge of braided channels on the maf. in all, the calculated bankfull discharges suggest much higher energy fluvial processes than today. considering the age and the dimensions of the orosháza palaeochannel, and also taking into account that the area of the maros catchment has not changed in the past 10-15 ka, we can suggest that high discharges were mainly related to the melting of glaciers in the upland drainage basin. acknowledgements the research was supported by huro/0901/266/2.2.2 project. 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(2012) sümeghy, b., kiss, t. 2011 discharge calculation of the paleochannels on the alluvial fan of the maros river, hungary, journal of environmental geography 4 (1–4), 11–17 timar, g., gábris, gy. 2008. estimation of water conductivity of the natural flood channels on the tisza flood-plain, the great hungarian plain, geomorphology 98, 250-261 timar, g., sümegi, p., horváth, f. 2005. late quarternary dynamics of the tisza river: evidence of climatic and tectonic controls, tectonophysics 410, 97–110. vandenberghe, j. 2003. climate forcing of fluvial system development: an evolution of ideas, quarternary science reviews 22, 2053– 2060. van dam, r.l. 2010. landform characterization using geophysics recent advances, applications, and emerging tools, geomorphology 137 (1), 57–73 williams, g.p. 1984. developements and applications of geomorphology, springer-verlag berlin heidelber. yadav, g.s., dasgupta, a.s., sinha, r., lal, t., srivastava, k.m., singh, s.k. 2010. shallow sub-surface stratigraphy of interfluves inferred from vertical electric soundings in western ganga plains, india quaternary international 227 (2), 104–115. journal of environmental geography journal of environmental geography 7 (3–4), 53–59. doi: 10.2478/jengeo-2014-0012 issn: 2060-467x bracketing the age of freshwater carbonate formation by osl dating near lake kolon, hungary györgy sipos 1*, orsolya tóth 1 , eszter pécsi 1 , csaba bíró 2 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 directorate of kiskunság national park, liszt f. u. 19, h-6000 kecskemét, hungary *corresponding author, e-mail: gysipos@geo.u-szeged.hu research article, received 02 september 2014, accepted 13 october 2014 abstract freshwater carbonates are unique depositions in the centre of the carpathian basin, with debated origin and age. their formation on the sand covered area of the danube-tisza interfluve is mainly related to lakes appearing in low lying interdune areas from time-totime. carbonate deposition is governed by various processes, but in general it can be traced back to climatic and concomitant surface and subsurface hydrological variations. therefore marl, limestone and dolomite layers can be a marker of environmental change. to identify the type of environmental change they may indicate absolute or numerical ages are needed. in previous studies this issue has been addressed by the means of radiocarbon dating. in the present study we attempted to bracket the age of freshwater carbonate formation with the help of optically stimulated luminescence dating and compared our results to radiocarbon data from the literature. in general, the luminescence properties of the investigated samples proved to be suitable for determining the age of the bedding and covering sediments. osl dates confirmed previous interpretations that freshwater carbonate formation in the area could have a peak around 10,5 ka. however, the termination of the deposition could not be unambiguously determined at the present stage of the analysis. the compound geomorphology and sedimentology of the study area call for further investigations. keywords: osl dating, freshwater carbonates, environmental change, blown sands introduction in the carpathian basin freshwater carbonate deposits may occur at various locations, but have mostly been reported from the blown sand covered area of the danube-tisza interfluve (dti). the extension and thickness of occurrences is highly variable as a consequence of the mosaic landscape and the complex formation of the deposits (sümegi et al., 2011). the source of the carbonates, precipitating and accumulating in the form of hard and compact limestone and dolomite benches is debated (fügedi et al., 2008; sümegi et al., 2011). nevertheless carbonate formation has been extensively studied and the major processes have been identified by molnár et al. (1981). deposition can traditionally be related: 1) to groundwater fluctuation and consequent precipitation of ca/mg rich salts from pore water above the fluctuation zone and 2) to shallow lakes where either co2 distraction by plants or time-to-time desiccation can lead to extensive carbonate formation (molnár and botz, 1996; fügedi et al., 2008). however, based on palinological data, sümegi et al. (2011) have shown that carbonate formation can also occur at deeper oligotrophic stages of lake evolution. nevertheless, each interpretation underlines the importance of climatic changes and parallel alteration of the hydrological regime. besides, they agree in that the ca-content of lake carbonates is higher than those precipitating from groundwater (molnár and botz, 1996; fügedi et al., 2008). the time of carbonate formation has been also debated, as previously it was primarily related to drier and warmer periods of the holocene, namely the boreal phase (mucsi, 1963). based on radiocarbon measurements on herbivorous gastropod shells enclosed by carbonate deposits at a typical limestone exposure, jenei et al. (2007) have proved that major carbonate formation started at around 13,0-11,5 ka (9500-11000 cal bc) and terminated at 6,9 ka (4900 cal bc), thus they pushed the peak of carbonate formation to the colder climate of the late glacial. these results were reinforced by the extensive study of sümegi et al. (2011) at another site in the basin of lake kolon, using also radiocarbon dating. based on their study, carbonate rich marls were formed between 13.6 ka and 10.5 ka (11,393–11,621 cal bc and 8311–8455 cal bc) with a peak around 11 ka. freshwater carbonate formation cannot be restricted to the late glacial however, as it was already suggested by jenei et al. (2007), who identified carbonate formation up till around 3.3 ka (1300 cal bc). a similar result can be deduced from the study of sipos et al. (2009) from another site on the dti where they dated the blown sand bedding of a carbonate rich lacustrine layer by using optically stimulated luminescence (osl) to 3,8 ka and the organic rich cover of it by using radiocarbon to 3,5 ka (1500 cal bc). 54 sipos et al. (2014) the aim of the present research is to provide further data for the time of carbonate formation on the dti by performing osl measurements on sediments below and above freshwater carbonate layers. these measurements provide also the possibility to compare the results of different numerical dating methods and therefore to achieve a more robust i nterpretation for the timing and environment of ca rbonate formation in the carpathian basin. study area lake kolon is situated on the western edge of the sand hills of the dti in a former channel of the danube (fig. 1). the elevated, central territory of the dti had been the alluvial fan of the danube throughout most of the pleistocene (pécsi, 1967). the shift of the river to its present day n-s direction is estimated to occur 30-40 ka ago, and generally explained by the subsidence of the baja and kalocsa depressions southwest of the area (jaskó and krolopp, 1991). the westward translation of the danube was presumably continuous, and a final phase of this process could be the formation of a 5-6 km wide valley on the western edge of the alluvial fan (fig. 1). lake kolon, and the study site is situated in this relatively deep lying area. the age of the channel and the termination of fluvial activity have not been determined yet, though radi ocarbon dating of lake sediments led sümegi et al. (2011) to the conclusion that lacustrine sedimentation started at around 27 ka (25 000 cal bc). after the danube had left the area, fluvial processes were overtaken mostly by eolian activity, especially intensive during the last glacial maximum (borsy, 1977; borsy, 1987; lóki et al., 1994). in these circumstances the basin was time-to-time covered by sand sheets. consequently, a hummocky landscape appeared with wind blown depressions and residual fig. 1 location and topography of the study site near lake kolon bracketing the age of freshwater carbonate formation by osl dating near lake kolon, hungary 55 ridges, which favoured the development of a mosaic network of wetlands and shallow lakes, adequate for freshwater carbonate formation (sümegi et al., 2011). however, as a result of height differences between sub-basins considerable spatial and temporal variations can be presumed in terms of carbonate formation. spatial variability is reinforced by the study of pécsi et al. (2014), when using high resolution drilling and ground penetrating radar for the delineation of dolomite platforms and carbonate rich layers in the area. osl dating was performed south of the present day lake (fig. 1). at the study site 3 sampling points were identified, the lowest and the highest being at 97.5 m and 99.0 m asl., respectively. the geomorphology of the area is compound, a deflational basin can be seen at sampling point p3, while point p2 and point p1 are located at the foot and on the top of a nw-se direction, relatively small positive form, interpreted as a left behind wing fragment of a larger parabolic dune, situated se of the form (fig. 1). materials and methods sedimentary features were mapped at the study site as described by pécsi et al. (2014) by using hand drills and a pürckhauer soil sampler. after revealing the spatial extension of carbonate rich layers 2 drillings were made to collect osl samples by using eijkelkamp type undisturbed sampling cylinders (fig. 2). at sampling point p3 the bedding of the freshwater dolomite was sampled from an artificial exposure, using the same cylinders. the aim of sampling was to collect sediments of relatively high sand content from below and above the very fine grained carbonate layers. in all, 9 samples were taken, each weighing about 200 g. from layers, in which only low sand content was presumed on the basis of orienteering drills, double samples were collected. the processing of these samples was started separately, however, in case it was necessary they were merged to receive an adequate amount of material for dating. in one case even the doubled sample did not yield enough datable grains (osz872/873). sample preparation was based on the techniques proposed by aitken (1998) and mauz et al. (2002) for coarse grain sample treatment. first the samples were wet sieved to separate the 90-150 μm grain size fraction, the typical grain size interval for blown sand sediments. subsequently, samples were subjec ted to repeated acid treatments (hcl and h 2o2) to remove their usually high carbonate and moderate organic matter content. the quartz content was d ivided from other minerals by heavy liquid separation (2.62 and 2.68 cm 3 ). in order to clean quartz, and to remove any remaining feldspars a 45 min hf etching was applied. grains were adhered to stainless steel sample holding discs by using silicone spray and a 4 mm mask, chosen as a compromise between signal intensity and the available low amount of material. the absorbed dose since deposition, termed as the equivalent dose (de) was determined by using the single aliquot regenerative-dose (sar) protocol (murray and wintle, 2000; wintle and murray, 2006), on a risø da-15 automated tl/osl system with a beta dose rate (sr/y) of 0.105±0.002 gy s −1 at the time of measurements. preheat temperatures were set between 200-240 °c depending on the results of dose recovery preheat plateau tests, performed on each sample. prior to the dose recovery aliquots were bleached by the blue leds of the risø reader at room temperature, and irradiated with a dose similar to the one determined through initial trial measurements. during the evaluation of d e some of the aliquots were rejected mainly for the following reasons: the recycling ratio (the ratio of the sensitivity co rrected osl response to the first regeneration dose and that of an identical dose at the end of the mea surement cycle) was outside 1.00±0.05, the error of de (mainly related to the fitting of the dose response curve) was larger than 10%, or the recuperation si gnal (the osl response given for zero irradiation as a matter of previous thermal treatment) was over 5% of the natural signal. the distribution of d e values usually had an overdispersion below 0.20, cons equently, and by considering the decision procedure of (bailey and arnold 2006) the central age model was applied for most of the calculations, however in one case, at sample osz869 (σ od=0.27) the minimum age model was chosen (galbraith et al., 1999; galbraight and roberts, 2012). fig. 2 sampling at the exposure beneath the carbonate bench by using steel cylinders 56 sipos et al. (2014) environmental dose rate was determined by using high resolution, low-level gamma spectrometry. dry dose rates were calculated using the conversion factors of adamiec and aitken (1998). wet dose rates were assessed on the basis of in situ water contents. samples below the fresh water carbonate layers were close to their saturation, consequently a lower vari ation was attributed to their water content in the past. samples above had a water content between 12-15 %, in their case a much larger error was assumed (table 1). the rate of cosmic radiation was determined on the basis of burial depth following the method of prescott and hutton (1994). results based on our preliminary investigations, we found that the quartz osl signal is dominated by the fast component in general if compared to the decay curve of the risø calibration quartz (180-255 µm) (fig. 3). therefore, the eolian sand of lake kolon seems to be suitable for adequate osl dating. nevertheless, in case of some aliquots the presence of a later, possibly medium component can be seen. to resolve the effect of this issue on dating further analysis has to be made. in order to minimize the effect of the medium component the first 5 channels (0.8 s) were integrated and used as an osl signal in later measurements. background was calculated from the last 50 channels of the decay curve. regarding dose recovery preheat tests samples were performing the best between 200 °c and 240 °c, recovered doses were close to unity in this te mperature region (fig. 4). a full dose recovery test was not performed at this stage of the investigation. another check on the suitability of the applied measurement protocol is the calculation of recycling ratios. concerning this parameter values were also acceptable in the above temperature range, and most of the measured aliquots proved to be adequate for further evaluation (fig. 4). the problem of recuper ation, however, at one samples appeared to be signif icant during the tests (osz870/871). therefore, the traditional sar protocol was replaced by the one advised by wintle and murray (2006), including an elevated temperature osl measurement (hot bleach) at the end of each regeneration cycle to decrease the effect of charge transfer (fig. 4). fig. 3 natural decay curve of an aliquot compared to that of the risø calibration quartz and a typical dose response curve of the same sample with the exception of one sample (osz875) 24 aliquots were subjected to the sar protocol in order to determine equivalent doses. the turnout rate of well behaving aliquots, passing all internal checks, was 70-90 % in four cases and only sample osz875 proved to be problematic and has to be tested further (table 2). this means that the applied settings and protocol was proper in most of the cases. the distribution of equivalent doses, with the exception of sample osz869 was unimodal and unskewed, meaning that there was an adequate exposure to sunlight during sediment transport, just as it can be expected from eolian samples (fig 5.). co nversely, the significant skewness of osz869 data may imply that exposure was not adequate and the sample experienced either a short transportation distance or it was deposited by water related pr ocesses (fluvial or lacustrine). table 1 sampling and radiometric data and the calculated dose rate of the samples id depth (cm) w (%) 238 u (ppm) 232 th (ppm) k (%) d* (gy/ka) osz867/868 180–190 11,0±5,0 2,07±0,20 6,51±0,96 0,85±0,09 1,75±0,08 osz869 230 34,0±2,0 2,07±0,20 6,51±0,96 0,85±0,09 1,43±0,07 osz872/873 75–85 34,0±2,0 1,19±0,12 3,54±0,35 0,17±0,01 1,99±0,06 osz870/871 120–130 23,0±4,0 2,96±0,29 8,85±0,89 0,16±0,01 2,10±0,08 osz874 100 26,6±4,0 2,99±0,30 10,33±1,03 0,17±0,01 1,71±0,06 osz875 100 27,0±4,0 2,99±0,30 10,33±1,03 0,17±0,01 1,71±0,06 bracketing the age of freshwater carbonate formation by osl dating near lake kolon, hungary 57 the results of gamma spectrocopical measurements and calculated dose rates are presented in table 1. ages, calculated as the quotient of equivalent doses and dose rates, have a 5-10 % relative error (table 2) and show a good stratigraphic correlation (fig. 6). in case of sampling point p1 the bedding of the carbonate layer was dated to the last glacial maximum (23.6 ± 1.2 ka), while the cover sediments to the beginning of the holocene (10.2 ± 0.6 ka). consequently, the timing of lacustrine freshwater carbonate formation can be assumed for a very broad time interval. if the stratigraphy of p1 is compared to that of p2 then the cover layer in p1 corresponds well to the bedding of carbonate in p2 (fig. 6). accordingly, the age of the later is also dated to the beginning of the holocene (10.8 ± 0.7 ka). unfortunately the cover sediments at p2 did not yield enough coarse material to carry out a successful measurement, therefore the termination of the process could not be determined. concerning p3 the bedding of the carbonate also had a similar age (table 2, fig.6) as before and confirmed previous measurements. in this case the two parallel samples were dated separately, and the two dates showed a good correspondence (10.9 ± 0.4 ka and 10.4 ± 0.7 ka) (table 2 and fig. 6). the mean of the ages representing the beginning of the holocene is 10.6 ka. fig. 4 results of dose recovery preheat tests (a and b) and sar internal checks (c and d) in case of two samples (osz869 and osz870/871) table 2 equivalent dose data and the calculated age of the samples id measured/rejected (pcs) age model de (gy) d* (gy/ka) osl age 1 (ka) osz867/868 24 / 18 cam 17,76±0,34 1,75±0,08 10,2±0,6 osz869 24 / 22 mam3 33,67±0,29 1,43±0,07 23,6±1,2 osz872/873 – – – 1,99±0,06 – osz870/871 48 / 40 cam 22,82±1,09 2,10±0,08 10,8±0,7 osz874 24 / 17 cam 23,59±0,12 1,71±0,06 10,9±0,4 osz875 18 / 8 cam 22,49±1,47 1,71±0,06 10,4±0,7 1 age is given by dividing de and d* 58 sipos et al. (2014) fig. 5 the distribution of equivalent doses in terms of the measured samples fig. 6 the stratigraphy of the profiles and the measured osl ages. the absolute height of freshwater carbonate layers is indicated on the inset bracketing the age of freshwater carbonate formation by osl dating near lake kolon, hungary 59 conclusions based on various tests, the luminescence properties of the sediments originating from the lake kolon area are adequate for conducting a reliable dating study, only recuperation can be an issue which has to be considered especially when dating younger sediments. the ages received at the present stage of analysis can be fitted to the radiocarbon data presented by jenei et al. (2007) and sümegi et al. (2011). the age of the sand layer at the base of the section is not identical to, but close to age of the earliest lacustrine layers identified by sümegi et al. (2011) at the central part of the lake’s basin. by considering the above and the dose distribution received for the material, we assume that this layer might represent the fluvial sand of the danube. based on the stratigraphy and the osl ages, it seems clear that there could be several phases of freshwater carbonate formation throughout the late pleistocene and holocene. one phase is suggested to occur in the end, or after the lgm, however its precise timing needs further analysis, as there is a nearly 13 ka age difference between the layers below and above the carbonate platform. another phase occurred after the topography had changed as a matter of blown sand movement, covering the carbonates of the first phase and forming a more pronounced topographical difference between the southern and northern part of the site. the bedding sediment of this phase is dated unambiguously to the onset of the holocene. if the four dates corresponding to each other within their errors are averaged then a mean age of 10,6 ka is received for this event. thus, carbonate formation occurred subsequently, though the termination of this phase could not be dated. however, based on the results of both jenei et al. (2007) and sümegi et al (2011) it is highly probable that there is a correspondence between the timing of carbonate formation on our site, at the centre of the kolon lake basin and at other sites of the dti. consequently, the peak of freshwater carbonate formation could be at around 10.5 ka in the region, and these deposits mark rather a relatively colder climate with variable water input, than a warm and dry environment. acknowledgement this research was supported by the european union and the state of hungary, co-financed by the european social fund in the framework of támop-4.2.4.a/ 2-11/12012-0001 ‘national excellence program’. references adamiec, g., aitken, m. 1998. dose-rate conversion factors: update. ancient tl 16 (2), 37–49. aitken, m.j. 1998. an introduction to optical dating. oxford university press, oxford, 266 p. bailey, r.m., arnold, l.j., 2006. statistical modelling of single grain quartz de distributions and an assessment of procedures for estimating burial dose. quaternary science reviews 25, 2475– 2502. doi: 10.1016/j.quascirev.2005.09.012 borsy, z. 1977. a duna–tisza köze homokformái és a homokmozgás szakaszai. alföldi tanulmányok 345, 43–53. borsy, z. 1987. az alföld hordalékkúpjainak fejlődéstörténete. acta academiae paedagogicae nyiregyháziensis. 11/h, 5–37. fügedi, u., pocsai, t., kuti, l., horváth, i., vatai, j. 2008. a mészfelhalmozódás földtani okai közép-magyarország talajaiban. agrokémia és talajtan 57 (2), 239–260. galbraith, r. f., roberts, r. g. 2012. statistical aspects of equivalent dose and error calculation and display in osl dating: an overview and some recommendations quatermary geochronology 11, 1–27. doi: 10.1016/j.quageo.2012.04.020 galbraith, r.f., roberts, r.g., laslett, g.m., yoshida, h., olley, j.m., 1999. optical dating of single and multiple grains of quartz from jinmium rock shelter, northern australia: part i, experimental design and statistical models. archaeometry 41, 339–364. doi: 10.1111/j.1475-4754.1999.tb00987.x jaskó, s., krolopp, e. 1991. negyedidőszaki kéregmozgások és folyóvizi üledékfelhalmozódás a duna-völgyben paks és mohács között. földtani intézet évi jelentése 1989-ről, 65–84. jenei, m., gulyás, s., sümegi p., molnár m. 2007. holocene lacustrine carbonate formation: old ideas in the light of new radiocarbon data from a single site in central hungary. radiocarbon 49 (2) 1017–1021. lóki, j., hertelendi, e., borsy, z. 1994. new dating of blown sand movement in the nyírség. acta geographica debrecina 32, 67– 76. mauz, b., bode, t., mainz, h., blanchard, w., hilger, r., dikau, r., zöller, l. 2002. the luminescence dating laboratory at the university of bonn: equipment and procedures. ancient tl 20, 53– 61. molnár, b., botz, r. 1996. geochemistry and stable isotope radio of modern carbonates in natron lakes of the danube–tisza interfluve, hungary. acta geol. hung. 39 (2), 153–174. molnár, b., szónoky, m., kovács, s. 1981. recens hiperszalin dolomitok diagenetikus és litifikációs folyamatai a duna–tisza közén. földtani közlöny 111, 119–144. mucsi, m. 1963. finomrétegtani vizsgálatok a kiskunsági édesvízi karbonát-képzıdményeken. földtani közlöny 93 373–86. murray, a.s., wintle, a.g. 2000. luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. radiation measurements 32, 57–73. doi: 10.1016/s13504487(99)00253-x pécsi, m. 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(ed.) környezettörténet. az elmúlt 500 év környezeti eseményei történeti és természettudományi források tükrében. hantken kiadó, budapest 409–420. sümegi, p., molnár, m., jakab, g., persaits, g., majkut, p., páll, d. g., gulyási, s., jull, t. a. j, törcsik, t. 2011. radiocarbon-dated paleoenvironmental changes on a lake and peat sediment sequence from the central great hungarian plain (central europe) during the last 25,000 years. radiocarbon 53 (1), 85–97. sümegi, p., mucsi, m., fényes, j., gulyás, s. 2005. first radiocarbon dates from the freshwater carbonates of the danube-tisza interfluve. in: hum, l., gulyás, s., sümegi, p., (eds.) environmental historical studies from the late tertiary and quaternary of hungary. szeged,university of szeged, department of geology and paleontology, 103–18. wintle, a., murray, a. s. 2006. a review of quartz optically stimulated luminescence characteristics and their relevance in singlealiquot regeneration dating protocols. radiation measurements 41, 369–391. doi: 10.1016/j.radmeas.2005.11.001 journal of environmental geography journal of environmental geography 10 (1–2), 23–29. doi: 10.1515/jengeo-2017-0003 issn: 2060-467x groundwater: quality levels and human exposure, sw nigeria adeyemi olusola1*, opeyemi adeyeye1, olufemi durowoju1 1department of geography, osun state university, p.m.b 4404, osogbo, osun state, nigeria *corresponding author, e-mail: adeyemi.olusola@uniosun.edu.ng research article, received 13 february 2017, accepted 6 april 2017 abstract groundwater serves as a source of freshwater for agricultural, industrial and domestic purposes and it accounts for about 42%, 27% and 36% respectively. as it remains the only source of all-year-round supply of freshwater globally, it is of vital importance as regards water security, human survival and sustainable agriculture. the main goal of this study is to identify the main cause-effect relationship between human activities and the state of groundwater quality using a communication tool (the dpsir model; drivers, pressures, state, impact and response). a total of twenty-one samples were collected from ten peri-urban communities scattered across three conterminous local government areas in southwestern nigeria. each of the groundwater samples was tested for twelve parameters total dissolved solids, ph, bicarbonate, chloride, lead, electrical conductivity, dissolved oxygen, nitrate, sulphate, magnesium and total suspended solids. the study revealed that the concentrations of do and pb were above threshold limits, while ph and n were just below the threshold and others elements were within acceptable limits based on guidelines for drinking water quality and nigeria standard for drinking water quality. the study revealed that groundwater quality levels from the sampled wells are under pressure leading to reduction in the amount of freshwater availability. this is a first-order setback in achieving access to freshwater as a sustainable development goal across less developed communities (ldcs) globally. to combat this threat, there is the need for an integrated approach in response towards groundwater conservation and sustainability by all stakeholders. keywords: groundwater, dpsir, cause-effect, peri-urban, communication tool introduction clean, safe and adequate availability of freshwater is vital to the survival of all living organisms and the smooth functioning of ecosystems, communities and economies (ibeh and mbah, 2007; akoteyon, 2013). availability and access to freshwater is also a global concern and a major unit of the sustainable development goals (sdgs). in terms of availability, two major sources of freshwater are surface water and groundwater. groundwater provides a valued fresh water resource to human population and constitutes about twothird of the fresh water reserves presently occupying various spaces across the world. groundwater is used for agricultural, industrial and domestic purposes. it accounts for about 50% of livestock and irrigation usage and just under 40% of water supplies, whilst in periurban areas, 98% of domestic water use is from groundwater (todd, 1980; stigter et al., 2006). groundwater can be put into different uses such as domestic, agricultural and industrial activities. these activities put a demand on groundwater thereby attenuating the remaining portion of available groundwater reserves (sangodoyin and agbawhe, 1992). activities such as these not only put pressure on global groundwater reserves but also affect the quality of groundwater (oluwande , 1983; macdonald et al., 2005; stigter et al., 2006; akoteyeon, 2013). groundwater quality comprises the physical, chemical and biological qualities (phillips et al., 2013). it becomes polluted when its quality is disturbed, whether the physico-chemical or the biological property. groundwater pollution can also be described as water contamination. it occurs when pollutants are released to the ground and make their way down into groundwater. it can also occur naturally due to the presence of minor and unwanted constituents, contaminants or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution (phillips et al., 2013). in most tropical climes such as nigeria, increase in the rate of population, a corollary effect of increase in the level of urbanization, industrial and agricultural activities are perceived to pose serious pollution threats with all its concomitant health hazard s on groundwater quality especially in urban and peri-urban areas (kehinde et al., 1989; adelana et al., 2008). groundwater in some climes contain specific ions (such as fluoride) and toxic elements (such as arsenic, lead and selenium) in quantities that are harmful to health, while others contain elements or compounds that cause other types of problems (such as the staining of sanitary fixtures by iron and manganese). most peri-urban towns in tropical countries such as nigeria are heavily populated due to rapid urbanization because of urban renewal processes; a growing planning process in urban planning, closeness to major urban centres, etc. it is based on this background that this research seeks to assess groundwater quality levels 24 olusola et al. (2017) across three conterminous local government areas (lgas) in osun state. these three lgas (boluwaduro, ifelodun and boripe) are close to osogbo, the osun state capital and they have been enjoying influx of people from osogbo who are settling down in these areas. these three lgas have been experiencing population growth (npc, 2006) and are fast becoming urbanized with unchecked physical planning process coupled with observed sanitary issues and difficulties in the use of freshwater especially for drinking purpose; the area becomes ideal for this kind of study. these factors (urbanization, unchecked physical development and sanitation issues, offshoot of population growth) are impacting on freshwater availability within the study area and thereby reducing its quality. with the present global challenge on freshwater, there is the need for developing countries such as nigeria to drive policie s that will protect her freshwater reserves and ensure sustainability. one of the channels through which the nations of the world can achieve protection and sustainability is encouraging more research into groundwater reserves using human-environmental models that can be used to understand interactions between nature and man in order to drive policies that are long sustainable and achievable. the aim of this study is to assess the spatial variation in groundwater quality across three conterminous lgas in osun state and present a sustainable water management approach. to achieve this aim, this study employed the use of dpsir (driving force, pressure, state, impact and response) model in understanding the importance and functions of groundwater quality in boluwaduro, boripe and ifelodun lgas in osun state. the main goal of this model is to identify the main cause-effect relationship between human activities and the state of water quality and present a response approach geared towards sustainable freshwater availability. borja et al. (2005) used the model together with other methodologies to identify the relevant pressures and impacts of water quality changes in estuarine and coastal areas. danielopol et al. (2003) reviewed the changes in the status of groundwate r ecosystems and the important driving forces, resulting from the direct or indirect impacts of human activities. their discussion divided the environmental pressures which are largely produced by human activities in two major classes, namely; groundwater quantity problems and the critical depletion of aquifers in many parts of the world and groundwater quality problems, where the systems are overloaded with contaminants. an application of the dpsir model based on the uniqueness of the study area and its peculiarities (being a tropical community, peri-urban zone, its absolute dependence on freshwater through groundwater abstraction and increasing emergence of light industries) becomes very relevant and sets to add more to growing body of knowledge on integrated water quality studies especially in tropical climes and offers a unique solution for similar less developed communities (ldcs) across the world. also, given globally recognized water scarcity, using the worlds accessible freshwater in a sustainable manner becomes critically important. study area three lgas were investigated in this research – ifelodun, boluwaduro and boripre (fig. 1, 7055’n, 4040’e; 7◦57’n, 4◦48’e; 7◦57’n, 4◦48’e). ifelodun has an area of 114km2 with a population of 96, 444 with its headquarters located at ikirun, boluwaduro has an area of 144km2 and a population of 70,954, with its headquarters located at atan-ayegbaju while boripe with an area of 132km2 and a population of 138,742 as at 2006 census has its headquarters at iragbiji. fig. 1 map showing study area and groundwater sampling points groundwater: quality levels and human exposure, sw nigeria 25 the study area (fig. 1) receives an average rainfall of 1,150 mm a year; it lasts from april to late october or early november (south-westerly winds prevail), though it eases off in july or august (august break). the dry season lasts from november to march which is the period of intense harmattan when the north-easterly dusty wind prevails, mixed with occasional intense heat. osun state is an inland state, lying mainly in the tropical rainforest, in the deciduous forest area which spreads towards the grassland belt of the study areas. climate here is less humid and hot than the greater part of south-western nigeria although the effect of the harmattan wind is strongly felt in the dry season. the towns are situated on a raised land which is well over 500 meters above the sea level and is drained by the tributaries of river osun. various economic activities are being carried out within the study areas. sizeable numbers of the populace within the zone are civil servants who also are into one form of petty trading. market structures within the zone are mostly periodic with few ones being patronized on a daily basis. the area boasts of various industries from local craft ones to light industries (food crops processing plants, auto-mechanic workshops, etc.) and few heavy industries (iron smelting, metal fabrication, etc.). due to large expanse of available arable land, the area is intensively cultivated for various crops while some are already being converted into industrial sites. methodology field survey was carried out before sample collection. this was necessary in order to examine the general characteristics of the area, determine the most feasible routes for sample collection and identify wells and their characteristics. communities where samples were taken are iree, obagun, otan-ayegbaju, ada, oba, erinpa, ikirun, ekoajala, iragbiji located within the local government areas boripe, boluwaduro and ifelodun (table 1). these areas were identified during the course of the reconnaissance and it was gathered that their source of groundwater which is mostly from wells is not too safe for drinking. dpsir model dpsir model is a chain of causal links starting with ‘driving forces’ (economic sectors, human activities) through ‘pressures’ (emissions, waste) to ‘states’ (physical, chemical and biological) and ‘impacts’ on ecosystems, human health and functions, eventually leading to political ‘responses’ (prioritization, target setting, indicators). describing the causal chain from driving forces to impacts and responses is a complex task, and tends to be broken down into sub-tasks, e.g. by considering the pressure-state relationship. a ‘driving force’ is a need. examples of primary driving forces for an individual are the need for shelter, food and water, while examples of secondary driving forces are the need for mobility, entertainment and culture (kristensen, 2004). driving forces lead to human activities such as transportation or food production, i.e. result in meeting a need. these human activities exert 'pressures' on the environment, as a result of production or consumption processes. table 1 location of sampled groundwater wells id geographic coordinates depth (m) flow nothing easting well 1 07°55' 46.221" 04°40' 30.370'' 7 perennial well 2 07°55' 44.207'' 04°40' 20.006'' 2 seasonal well 3 07°56' 08.450'' 04°43' 41.446'' 2 perennial well 4 07◦56' 11.886'' 04°43' 46.192'' 8 seasonal well 5 07°56' 13.011'' 04°43' 30.199'' 12 seasonal well 6 07°53' 27.352'' 04°42' 47.338'' 12 seasonal well 7 07°53' 32.399'' 04°42' 46.743'' 12 seasonal well 8 07°54' 22.510'' 04°41' 12.610'' 2 seasonal well 9 07°54' 20.596'' 04°41' 15.500'' 2 perennial well 10 07°56' 33.035'' 04°37' 34.008'' 6 perennial well 11 07°55' 02.547'' 04°34' 31.910'' 2 seasonal well 12 07°55' 03.512'' 04°34' 28.859'' 6 perennial well 13 07◦54' 31.711'' 04°34' 41.251'' 14 seasonal well 14 07°55' 37.113'' 04°39' 13.297'' 7 perennial well 15 07°55' 13.326'' 04°40' 08.198'' 14 seasonal well 16 07◦55' 07.601'' 04◦40' 09.509'' 2 seasonal well 17 07°56' 22.387'' 04◦44' 39.922'' 14 seasonal well 18 07°56' 19.271'' 04°44' 40.429'' 2 seasonal well 19 07°56' 19.115'' 04°44' 38.494'' 2 seasonal well 20 07°56' 50.558'' 04°47' 24.027'' 12 seasonal well 21 07°56' 51.940'' 04°47' 24.439'' 12 seasonal as a result of pressures, the ‘state’ of the environment is affected; that is, the quality of the various environmental compartments (air, water, soil etc.) in relation to the functions that these compartments fulfil. the ‘state of the environment’ is thus the combination of the physical, chemical and biological conditions. the changes in the physical, chemical or biological state of the environment determine the quality of ecosystems and the welfare of human beings. in other words, changes in the state may have environmental or economic ‘impacts’ on the functioning of ecosystems and human lives (kristensen, 2004). a ‘response’ by society or policy makers is the result of an undesired impact and can affect any part of the chain between driving forces and impacts. dspir was applied as a guiding model for a welldeveloped water quality study in the light of sustainable freshwater management. 26 olusola et al. (2017) driving forces and pressures the need for shelter, healthy living and improved financial status were identified as the driving forces acting upon the sustainable use of freshwater supply within the zone. a corollary effect of these forces is increased population growth which in turn affects urbanization and industrialization. as a basic pressure, population growth was analysed using existing records between 2006 and 2011 (npc, 2006) and possible contamination sources that predispose groundwater to pollution were identified on the field. state and impact the state of the groundwater in terms of its quality was determined from the laboratory using standard protocols and measures (apha et al., 2008) at the university of ibadan, department of agronomy. a total of twenty-one (21) samples were collected from ten (10) peri-urban communities scattered across the three local government areas (boripe, boluwaduro and ifelodun). the water samples were collected with the aid of polyethylene bottles (apha et al. 1998) and each location was determined using a global positioning system. also, the state of each of the wells was determined in terms of depth and volume of water was qualitatively described using seasonality. at the time of sampling, bottles were thoroughly rinsed two to three times with the well water. the samples were taken immediately to the laboratory to determine their physicochemical properties. each of the groundwater samples was analyzed for 12 parameters: total dissolved solids (tds), ph, bicarbonate, chloride, lead, electrical conductivity, dissolved oxygen, nitrate, sulphate, magnesium and total suspended solids using standard laboratory procedure (apha et al., 1998). the spatial variation of the physico-chemical properties was determined using charts across the 21 communities. based on who and nigeria standards, average values of each of the parameters were compared against the who standard to ascertain the level of exposure to risks being posed by the consumption of freshwater within the study area. risk map for threatening parameters was produced using arcgis 10.1 in form of dot map using proportional circles. response the present capacities of major stakeholders were evaluated to understand how to cope with the impact of polluted groundwater and finally presenting a required management intervention that is both long-term and short-term. results driving forces and pressures the driving forces identified within the study area are population growth and urbanization. these activities arise as a result of human needs for food, water, shelter and health. due to population increase (npc, 2011) across the area, there is increase in the rate of urbanization and agricultural practices. on the average, across the three lgas, population increased by over 14%. by 2050, it is expected that global water demand will increase by 55 percent (cap-net, 2016) mainly due to growing demands from manufacturing, thermal electricity generation and domestic use. as population increases across the study area (fig. 2) so does production of wastewater and other products that predisposes groundwater to being polluted. by 2020 the proportion of urban population in ldcs is predicted to surpass 50% and it is expected that 57% of the world’s population will live in cities (un report, 1997). going by the trend, peri-urban communities are likely to have greater influx of urban dwellers of which a large proportion will be poor. this in itself implies increase in pressure on domestic and drinking water supply, sanitation and food supply (danielopol et al., 1997). fig. 2 graphical representation of population growth across the study area agricultural practice exerts pressure on the environment and it is a major source of high concentration of nitrate in groundwater in wells, through the application of chemical manure. fertilizers and pesticides applied to crops eventually reach underlying aquifers particularly if the aquifer is shallow and not protected by an overlying layer of low permeability materials. state and impact the values in table 2 shows that well 13 has the highest ph value followed by well 6. ph is a measure of the acidic or basic nature of a solution ph average (6.5) value for groundwater is within the permissible level (table 3). it has been noted in the nigeria standard for drinking water quality (nsdwq, 2007) that ph usually does not have a direct bearing on consumers of water. do is a measure of the amount of oxygen level in a body of water. it is affected by pressure, temperature and salinity. average value for do across the studied wells is 10.6. the average value for do here is above the threshold limit (nsdwq, 2007). excess dissolved oxygen in water bodies can cause external bubbles (emphysema), a rare occurrence that affects the skin and other tissues (kumar et al., 2007). groundwater: quality levels and human exposure, sw nigeria 27 for calcium, well 14 appeared with the highest value and well 6 for tds. well 2 and 10 has the highest value for cl. calcium concentration, cl and tds appears with an average of 21.40mg/l, 20.9 mg/l and 20.6mg/l respectively and they are well within acceptable standard (table 3). the palatability of drinking water rated by panels of tasters in relation to its tds level is as follows: excellent, less than 300 mg/l; good, between 300 and 600 mg/l; fair, between 600 and 900 mg/l; poor, between 900 and 1,200 mg/l; and unacceptable, greater than 1,200 mg/l (who, 1996a, b). tds concentrations across sampled wells are quite low and there is the tendency for the water to become flat and insipid in taste (kumar et al., 2007). table 3 nigeria standard for water quality (nsdwq, 2007) physico-chemical parameters nsdwq ph 6.5 -8.5 ec (µs/cm) 1000 tds (mg/l) 500 tss (mg/l) 500 chloride (mg/l) 250 nitrate (mg/l) 50 sulphate (mg/l) 100 bicarbonate (mg/l) calcium (mg/l) 75 magnesium (mg/l) 0.20 lead (mg/l) 0.01 dissolved oxygen (mg/l) 5.0 magnesium (mg) concentration as observed in the study is higher than the sulphate (so4) level. well 15 has the highest concentration level of mg exceeding the permitted level without any known effect on human health. as for sulphate, well 14 and 21 has the highest concentration level. so4 has an average concentration of 1.13mg/l lower than the permitted class given by nsdwq (2007). it has been noted that low so 4 concentration has no effect on human health. well 10 has the highest level of nitrate concentration. across the studied wells, no3 has an average value of 1.04mg/l which is well within the permitted standard globally. for lead, the highest concentration was observed in well 13 (0.49mg/l). lead across the study wells presents an average value of 0.266mg/l exceeding the permitted threshold level of 0.01 mg/l. from the study, lead has been found to be highly concentrated in most wells across obagun, obaoke, oba – oke and iree. most wells across the study area are shallow and particularly these wells are sited close to auto repair workshops, such as; auto mechanic, auto welding and auto painting. wastes disposal from these workshops found their way into the soil profile and contaminate the aquifer level resulting in groundwater pollution due to their shallowness. pb is quite deadly and it results in several diseases which are harmful to the human health especially children. the presence of pb above the normal threshold (who, 1996a; nsdwq, 2007) results in carcinogenic diseases, table 2 physico-chemical result of groundwater analyses across the twenty-one communities id ph ec (µs/cm) tds mg/l tss mg/l cl mg/l no3 mg/l so4 mg/l hco3 mg/l ca mg/l mg mg/l pb mg/l do mg/l well 1 6.71 542 20.5 1.4 17.8 0.8 1.2 0.07 20.5 3.1 0.34 11 well 2 5.66 432 18 0.5 35.5 0.6 1.1 0.19 19.1 3.8 0.35 9 well 3 6.83 512 21.8 1 22.5 0.9 1 0.1 18.5 2.9 0.43 10 well 4 6.71 842 22.4 1.5 27 1.3 1 0.12 17.35 2.2 0.32 12 well 5 6.83 422 20.6 1.19 25.6 1.1 1.5 0.16 19.8 1.7 0.2 13 well 6 6.24 362 33.2 0.8 24.5 1.2 0.9 0.08 17.3 1.8 0.19 11 well 7 6.31 392 30.4 0.65 21.5 1 1.6 0.07 21.5 1.9 0.17 12 well 8 6.55 545 26.8 1.11 20.6 1.4 1.1 0.06 22.8 2.15 0.22 9 well 9 6.53 792 20 0.92 17.3 1.7 1.2 0.05 26.1 2.35 0.3 8 well 10 6.71 382 25.5 0.85 35.5 1.8 0.8 0.16 25.3 2 0.26 8 well 11 6.75 372 24.2 0.7 18 0.4 1 0.2 18.75 4.19 0.4 8 well 12 6.82 322 23.2 1.1 21 1.1 1.1 0.02 22.8 2.6 0.28 9 well 13 9.92 682 17.9 0.6 18.5 0.9 0.7 0.16 27.33 2.8 0.49 12 well 14 6.36 332 16.5 0.9 13.8 1.1 1.7 0.14 35.1 3.3 0.31 13 well 15 6.23 352 14 0.3 12.9 0.7 0.9 0.1 29.2 4.8 0.33 11 well 16 6.54 662 13.6 0.45 18 0.9 1.6 0.09 18.7 2.9 0.21 12 well 17 6.26 352 20.3 0.25 19.2 0.7 1.4 0.11 16.5 3.15 0.26 12 well 18 6.55 342 18.6 0.4 21 1.1 1.6 0.16 17.1 2.9 0.18 11 well 19 6.52 342 19.1 0.3 16 1.3 0.8 0.12 19.3 1.6 0.14 11 well 20 6.85 602 12.7 0.22 13 0.8 1 0.1 18.6 1.45 0.1 10 well 21 6.8 852 14.8 0.18 20 1.1 1.7 0.08 17.8 2.15 0.11 11 average 6.70 496.90 20.67 0.73 20.91 1.04 1.19 0.11 21.40 2.65 0.27 10.62 28 olusola et al. (2017) interference with vitamin d metabolism and it affects mental development in infants. bicarbonate, hco3-, is always expected to be quite high especially in groundwater levels with low levels of calcium and magnesium. it serves as a control on water ph. well 2 has the highest bicarbonate level (0.19mg/l). the average value for hco3 across the studied sites is 0.111 mg/l. the highest concentration level of tss was observed in well 4 (1.5mg/l), and an average of value of 0.696 mg/l across all wells. tss is well within the permitted level. it is quite clear that most wells within the study area are quite shallow. hence, they are susceptible to contamination from activities around. the deepest well is about 12 meters (table 1). this explains the reason why some of the wells are seasonal. the extraction is from weathered regolith not deep enough to sustain water availability all year round. the shallowness of the well suggests that contaminants get into the freshwater zone rather easily. the pathway through which most of the groundwater within the study area gets polluted is through point sources as observed across the studied wells. from the state of groundwater quality across the studied wells vis-a-vis the who (1996a) and nsdwq (2007), levels dissolved oxygen (do) and lead (pb) within the wells poses high risk to human health and survival within the study area (table 4). nitrate and ph are just within par while the rest are well within acceptable limit (table 4). the two high risk parameters are presented in fig. 3 and 4 to show variation in concentration across the study area. fig3 risk map showing pb concentration in the study area fig.4 risk map showing do concentration in the study area response the cycle of hydrological processes sustains life and serves as a means of providing freshwater on the earth surface (cap-net, 2016). freshwater is a natural asset that must be protected to ensure that the essential ecosystem services it provides continue. expected response based on observed pressures and impact is to recognize that water is a scarce resource used for many different purposes, functions and services; therefore, water management has to be holistic and carefully consider different demands in view of available resources and threats. it is therefore expected that effective management of groundwater should encompass seeking non-conventional water sources, such as reclaiming or desalinizing. also, addressing sourcepoint pollution (i.e. precluding waste streams from entering natural water bodies) is among measures that can effectively curb this problem. specifically, all water producing wells within the study area should meet minimum standards for well construction mostly in terms of depth. furthermore, proper well location with minimum standards from potential sources (auto repair workshops, dumpsites, etc.) of contamination must be set. on the part of the government, regulatory bodies should be empowered and made to employ the polluted pay principle and good practice should be adopted. in order to effectively achieve the expected goal and meet global sustainable demands, alongside desirable socioeconomic development by prioritizing social equity, environmental sustainability and economic efficiency, health-sanitation officers should be properly equipped to enforce environmental healthitable 4 groundwater quality matrix (red: high risk; yellow: medium risk; blue: no risk ph ec tds tss cl no3 so4 hco3ca mg pb do ifelodun boripe boluwaduro groundwater: quality levels and human exposure, sw nigeria 29 ness. a more drastic approach to solving polluted groundwater across peri-urban centres in ldcs is the establishment of central borehole system careful constructed in clusters of communities based on stakeholder participation right from the feasibility study to the construction of the water system. conclusion the information obtained from this shows that two the levels of two parameters were found to be at above the threshold, two parameters were found to be at around the threshold limit while the remaining eight parameters were within the acceptable limits. in addition, the research has shown that groundwater quality levels from the sampled wells are under pressure threat due to increase in population and urban activities. these drivers put a lot of pressure on the environment thereby increasing pollution risk from point sources such as dumpsites, metals from autorepair workshops and chemicals due to intense agricultural practices. the resultant impact is that there is a grave danger on health especially on the urban poor utilizing groundwater for human consumption without any form of treatment. globally, there is little or nothing that mankind can do to change water availability in the natural water cycle. however, on a local scale, natural water cycle supports numerous smaller man-made water cycles that critically alter overall water availability. there is therefore the need for better management, i.e. improved economic efficiency of these man-made water cycles to ensure sustainable development. reducing pollution and collecting, recycling and reusing wastewater are a first order approach to tackle this menace within these communities and other ldcs in order to sustain human lives and create an environment that is sustainable and liveable. references adelana, s.m.a., t.a. abiye, d.c.w. nkhuwa, c. tindemugaya, m.s. oga. 2008. urban groundwater management and protection in sub-saharan africa. in: adelana s.m.a and macdonald, a.m (eds) appliedgroundwater studies in africa. crc, boca raton, fl, pp 231–260 akoteyon, i. s. 2013. hydrochemical studies of groundwater in parts of lagos. southwestern nigeria. bulletin of geograohy, physical geography series (6), 27–42. doi: 10.2478/bgeo-2013-0002 apha, awwa, wef 1998. standard methods for the examination of water and wastewater. 20th edn., apha, washington, dc. borja, a, galparsoro i, solaun o, muxika i, tello m, uriarte a, et al 2005. the european water framework directive and the dpsir, a methodological approach to assess the risk of failing to achieve good ecological status. estuar coast shelf sci 66:84–96. doi: 10.1016/j.ecss.2005.07.021 cap-net, 2016. ecosystem functions and services: integrated water resources management. training manual. online available at: www.cap-net.org danielopol, d, griebler, c, gunatilaka, a, notenboom j. 2003. present state and future prospects for groundwater ecosystems. environ conserv 30(2): 104–30. doi: 10.1017/s0376892903000109 ibeh, l.m., mbah, c.n. 2007. surface characteristics of urban rivers in enugu south eastern nigeria. world journal of biotechnology 8(2), 1412–1417. kehinde, m.o., loehnert, e.p. 1989. review of african groundwater resources. journal of african earth sciences 9, 179–185. doi: 10.1016/0899-5362(89)90019-5 kumar, m., kumari, k., ramanathan, a.l., saxena, r. 2007. a comparative evaluation of groundwater suitability for irrigation and drinking purposes in two intensively cultivated districts of punjab, india. env. geol., 53: 553–574. doi: 10.1007/s00254-0070672-3 macdonald, a.m., kemp, s.j. davies, j. 2005. transmissivity variations in mudstones. ground water 43, 259–269. doi: 10.1111/j.1745-6584.2005.0020.x npc (national population census) 2006. details of the breakdown of the national and stateprovisional population totals. official gazette 96 (2), 1–42, federal republic of nigeria, abuja. national population commission. 2011. nigeria's over 167million population: implications and challenges. retrieved march, 10, 2012 nsdwq, 2007. nigerian standard for drinking water quality. nigerian industrial standard nis 554, standard organization of nigeria, p30. oluwande, p. 1983. guide to tropical environmental health engineering. nigerian institute of social and economic research ibadan (niser), ibadan, pp. 141-147. phillips, a.j., gerlach, r., lauchnor, e., mitchell, a.c., cunningham, a.b., spangler, l. 2013. engineered applications of ureolytic biomineralization: a review. biofouling 29(6), 715–733. doi: 10.1080/08927014.2013.796550 sangodoyin, a.y., agbawhe, o.m. 1992. environmental study on surface and groundwater pollutants from abattoir effluents. bioresource technology 41(3), 193–200. doi: 10.1016/09608524(92)90001-e stigter, t. y., ribeiro, l., carvalho dill, a. m. m. 2006. application of a groundwater quality index as an assessment and communication tool in agro-environmental policies two portuguese case studies. journal of hydrology 327(3–4), 578–591. doi: 10.1016/j.jhydrol.2005.12.001 todd, d.k., mays, l.w. 2005. groundwater hydrology, 3rd edition. john wiley and sons inc. p, 652. un report (united nations report) 1997. world urbanization prospects: the 1996 revision. new york, usa: un secretariat, population division. who (world health organisation), 1996a. guidelines for drinking water quality, vol. 2: health criteria and other supporting information, second ed. world health organisation press, geneva. who (world health organisation), 1996b. water quality monitoring: a practical guide to the design and implementation of freshwater quality studies and monitoring programmes. e and fn spon, london, uk. journal of environmental geography 5 (1–2), 11–19. morphological and hydrological characteristics of paleo-channels on the alluvial fan of the maros river, hungary borbála sümeghy * , tímea kiss department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: sumeghy@geo.u-szeged.hu abstract the aim of our research was to identify and map the paleo-channel systems on the alluvial fan of the maros river and to analyse their spatial characteristics. the study on flow directions, horizontal channel parameters and paleo-discharge of the channels can help to forecast the maximum flood discharge and channel changes influenced by climate variations. the paleo-channel generations on the maros alluvial fan form 13 zones with well defined boundaries. these zones can be either dominated by meandering (5), braided (2), or the mixture of meandering and braided patterns (3). the remaining three paleo-channel zones exhibit an anastomosing pattern but they were not analysed in this study. the horizontal morphological parameters of the braided, the meandering and the misfit channels were measured. based on these morphometric parameters and regional discharge equations the bankfull discharge of the meandering zones was calculated. the greatest discharge was around 2655 m 3 /s while the smallest was 27 m 3 /s in case of a misfit paleo-channel. based on the slope conditions the alluvial fan was divided into three parts. the greatest slope (31.0 cm/km) was found in the central part of the alluvial fan, whilst slightly lower slopes (23.8 cm/km and 24.9 cm/km) characterise its axial and distal parts. these parameters refer to a normal radial profile of an alluvial fan. the channel pattern changes are in close relation with differences in slope. this is the most obvious in zone no. ix, where braided channels transform into meandering and then braided again from east to west in accordance with slope conditions. keywords: paleo-channel, paleo-discharge, morphometric parameters, slope conditions introduction paleo-hydrological data play an important role in understanding the response of rivers to climate change. for example precipitation and runoff conditions can be reconstructed by calculating paleo-discharge data. there are several methods to reconstruct the hydrological conditions of the past. some studies use proxy data, for example the ratio of stable oxygen isotopes or the rate of the highresolution magnetic susceptibility, but morphometric parameters of alluvial channels can provide more precise data (stein et al., 2004; carson and munroe 2005; scheurle et al., 2005; saenger et al., 2006). scheurle et al. (2005) applied paleo-oceanographic stable oxygen isotope (δ 18 o) to determine paleo-discharge of the elbe river. they analysed the rate of isotopes in calcareous shells of marine animals and correlated it to salinity, thus the ratio of saltyand freshwater (referring to paleo-discharge) were estimated. saenger et al., (2006) applied the same method, but besides they modelled the precipitation conditions of the drainage area too. sedimentological, geochemical and micropaleontological proxy data of surface sediments also allow the reconstruction of paleo-climatic conditions. highresolution magnetic susceptibility record was used to estimate sediment fluxes and their relationship to paleoenvironmental changes by stein et al. (2004). the variability of sediment fluxes during the holocene was related to the changes in discharge and coastal erosion input. carson and munroe (2005) applied dendrohydrology to reconstruct mean annual discharge and precipitation data. the width of an annual tree ring reflects the yearly hydrological conditions and also refers to the near-surface temperature, evapo-transpiration and precipitation (werritty and leys, 2001). since there is a close relationship between discharge and different channel parameters, a wide range of paleodischarge calculations exist (gábris, 1970, 1986; sylvia and galloway, 2006; timár and gábris, 2008). for example sylvia and galloway (2006) reconstructed late pleistocene discharge mostly based on horizontal channel parameters of the paleo-channels, whilst lauriol et al. (2002) beside morphometry also analysed fluvial deposits to study paleo-climatic conditions. the most frequently studied channel parameters in paleo-discharge calculations are radius of curvature, wavelength, channel width and depth. williams (1984) emphasized the regional validity of these equations, thus the equations can be used only in the same geographical environment and for the same river dimensions the equations were derived from. in the carpathian basin gábris (1986, 1995) and timár and gábris (2008) made paleo-discharge calculations using meander wavelength to study holocene climate change and the discharge of scour-channels. on the hungarian part of the maros alluvial fan dense paleo-channel systems can be identified, but their flow directions and pattern have not been studied in detail before, though they can provide useful information on late pleistocene and holocene climate changes. the aim of the present study was to identify the abandoned channels and to determine their horizontal mo rphometric parameters on the hungarian part of the alluvial fan. our further goal was to calculate paleodischarges using existing equations. meanwhile, slope conditions, being potential causes of longitudinal pattern change on the alluvial fan were also investigated. 12 sümeghy and kiss (2012) study area the alluvial fan of the maros river has a semicircular form with a 80-100 km radius (mike, 1991). it is bordered by the körös river and its floodplain in north and by the tisza river and its incised floodplain in west. the alluvial fan stretches also to romania and serbia, but in the present study only the hunga rian part (3640 km 2 ) was studied (fig. 1). the area of the alluvial fan is affected by tectonic movements (nádor et al., 2005, 2007). certain parts are characterised by intensive subsidence, e.g. the békés basin or the makó–hódmezővásárhely graben, while others are sinking more slowly, thus exhibit a relative uplifting, e.g. the battonya– pusztaföldvár horst (joó et al. 2000; dövényi 2010). throughout the quaternary the direction of channels was controlled by the different tectonic activity of the above mentioned areas. the channels slid down from the rising areas and changed their directions towards the sinking basins frequently (nádor et al., 2005), thus the body of the fan is characterised by interc alated sediment layers (molnár, 2007). however, the history of the alluvial fan has not been cleared yet. according to mike (1991) the evolution of the all uvial fan started in the late pliocene when the south transylvanian basin was drained by the maros (somogyi, 1961). however, based on the sedimentary sequences of the alluvial fan molnár (2007) concluded that the development of the alluvial fan started just in the early pleistocene. according to andó (1976) and borsy (1989) the formation of the youngest parts started in the late pleistocene or in the early holocene. it was supported by the meas urements of gábris (1986), who revealed that the száraz brook was an active maros channel or tributary channel in the boreal phase. according to nádor et al. (2007) the maros river turned to its present direction during the middle or late holocene, as it is r eflected by a gravel layer in the sedimentary structure of the alluvial fan. the reconstruction of the deve lopment of the alluvial fan is especially questio nable along its boundaries, where the sediments of the maros are intercalated with that of the neighbour ing rivers (molnár, 2007). the flow directions of the paleo-channels are not well known either. according to márton (1914) the maros had no well-defined channel until the pleistocene, as it was split into several secondary channels. the frequent changes of river course were also emphasized by andó (2002), who mentioned four main flow directions during the pleistocene. according to mike (1991), the holocene maros channel shifted on the alluvial fan frequently, but in each case at first it turned to north-east then towards to the south. however, somogyi (1961) supposed a similar drainage network like nowadays at the end of the pleistocene. the paleo-discharge was determined just for a limited number of paleochannels (gábris, 1986) and it showed that in the boreal phase mean discharge was similar (160 m 3 /s) to the present-day discharge of the maros (fiala et al., 2006). the surface of the alluvial fan is covered by loess, sandy loess sand fluvial sediments containing silt and clay (dövényi, 2010). the alluvial fan is rich fig. 1 the study area is on the hungarian part of the maros alluvial fan (srtm model) morphological and hydrological characteristics of paleo-channels on the alluvial fan of the maros river, hungary 13 in fluvial forms, dominated by paleo -channels, scourchannels and cut-offs, though in some places sand deposits were blown out and dunes were formed. the battonya horst is poor in fluvial forms, as it lies more than 3 meters above the alluvial fan surface and is mostly covered by loess. methods to identify the fluvial forms on the maros all uvial fan a digital elevation model (dem) was created using 1:10,000 scale topographical maps under arcgis 10. software with a horizontal resolution of 2 m. based on the dem, the paleo-channels, mid-channel bars and point-bars were identified and used for determining channel patterns (braided, meandering, anastomosing and misfit) following the classification of leopold and wolman (1957) and the definitions of rosgen (1996). considering the pattern and the spatial distrib ution of forms on the surface the alluvial fan was d ivided into 13 paleo-channel zones. in case of the braided paleochannels their width (w), channel length (lc) and valley length (lv) were measured, and their sinuosity (s) (channel length / valley length) was calculated. in case of the meandering and misfit paleo-channels the radius of curvature, (rc), half-wavelength (l) and chord-length (h) were determined. the radius of curvature was deriveted from the largest circle fitting at least at three points to the centre-line of the meander. half-wavelength was measured between two inflection points along the centre-line (the inflection point was understood as the mid point of the straight section between two bends). chord-length was equal to the straight distance between two inflection points. laczay (1982) classified river bends based on the ratio of half-wavelength and chord-length ( = l/h), and defined various development phases. gábris (1986) suggested that from laczay’s classes only the so called developed and well-developed meanders should be used in paleo-discharge calculations. finally, palaeo-discharges were calculated applying the regional equations developed by sümeghy and kiss (2011). during the research we were regularly faced to the problem of sudden pattern changes along the paleo-channel zones. to resolve this phenomenon, the slope conditions of the alluvial fan were also studied. the alluvial fan was divided into three belts (axial, central and distal) according to the basic morphological units of such forms (see rachocki, 1981). the slope of belts was determined along radial lines following the paleo-channel zones. to study slope variations in detail, the slopes of the floodplain and the channel were also measured. floodplain slope was determined along the paleo-channels, ca. 10 m away from banklines, whilst channel slope was defined along the centre-line of the paleo-channel. the entrenchment ratio was calculated by dividing the floo dplain slope with the channel slope. results and discussion morphology of the paleo-channels paleo-channels appear in almost continuous zones (13) with well-defined boundaries (fig. 2). the mean length of paleo-channel zones is 42 km and the adjacent floodplain sections are 4.1-8.7 km wide in average. zone no. ix has the largest territory (474 km 2 ), while zones no. ii and vi are the smallest (ca. 99 km 2 ). each paleo-channel within a zone has a typical channel pattern, though in some cases pattern-changes could also be detected (table 1-2). two of the 13 zones (no. iii and ix) are dominated by braided channels, though occasionally meandering sections do also appear. five zones have only meandering paleo-channels, two of them are misfit (no. i and v). three zones (no. xi, xii and xiii) are dominated by meandering channels with short braided sections. the remaining three zones (no. ii, vii and x) exhibit an anastomosing pattern (although sub-channels are meandering, due to uncertain bifurcation points these were not analysed further on). table1 morphometric parameters of braided paleo-channels (a: area, w: channel width, lc: channel length, lv: valley length, s: sinuosity) zone a (km 2 ) channel pattern w (km) lc (km) lv (km) s min max iii. a 164 dominantly braided 2.3 4.4 62.2 50.2 1.24 b 146 1.8 3.5 ix. 474 dominantly braided 1.1 3.4 51.1 43.5 1.17 xi. 452 dominantly meandering 0.8 3.0 13.0 11.8 1.10 xii. 213 dominantly meandering 0.8 5.1 20.4 18.0 1.10 xiii. 375 dominantly meandering 1.6 2.5 12.0 11.6 1.04 14 sümeghy and kiss (2012) table 2 mean values of horizontal channel parameters in the meandering paleo-channel zones and at subordinate meandering sections (rc: radius of curvature, l: half-wavelength, h: chord-length) zone area (km 2 ) zone pattern number of analysed meanders horizontal parameters (m) rc l h i. 296 meandering 42 202 845 519 misfit 81 106 340 229 iv. 164 meandering 15 312 1201 710 v. 207 meandering 30 208 1008 435 misfit 137 67 228 147 vi. 99 meandering 14 528 2175 1246 viii. 187 meandering 13 478 1472 1113 ix. 452 dominantly braided 14 587 2394 1402 xi. 348 dominantly meandering 55 349 1331 807 xii. 213 dominantly meandering 18 297 958 712 xiii. 375 dominantly meandering 32 656 1775 1390 fig. 2 paleo-channel network on the maros alluvial fan. the paleo-channel zones are indicated by roman numbers (i-xiii). in the lack of absolute age data, at the present stage of the research numbering is based on the morphologically presumed succession of channels morphological and hydrological characteristics of paleo-channels on the alluvial fan of the maros river, hungary 15 the minimal width of braided channels varies between 0.8 and 2.3 km, while their maximal width is between 2.5 and 5.1 km (table 1). the two dominantly braided channel zones (no. iii and ix) stretch from the apex of the alluvial fan to its distal, western border, therefore their channel length is between 51.1 and 62.2 km, whilst the length of their valley is 43.5 and 50.2 km respectively. the sinuosity of the braided channels is between 1.0 and 1.2, which fits well to the leopold and wolman’s classification (1957), having a 1.5 value as a threshold. the forms of the two dominantly braided channels are almost entirely recognisable, though some sections have been reworked by younger meandering and misfit channels. their natural levees are approximately 1.0-1.5 m higher than the surrounding floodplain surface (fig. 3). on the northern part of the alluvial fan, which is dominated by meandering zones, three braided paleochannel remnants were found. they are only 12.0-20.4 km long and their valley length is 11.6-18.0 km. certain sections were reworked by meandering channels, thus the banks and the bars partially disappeared. meandering channels occupy the southern and western parts of the alluvial fan. concerning the meandering zones the value of mean rc varies between 202 and 656 m, l is 845-2394 m, while h is between 435 and 1402 m (table 2). however, the number of the analysed bends was quite different in each zone. the fewest developed and well-developed meanders (in all 13) were identified in paleo-channel zone no. viii, while there were 55 such meanders in the zone no. xi. the greatest horizontal channel parameters were measured in zone no. xiii (rc=656 m), and in zone no. ix (l=2394 m, h=1402 m). the smallest mean ratio of curvature (rc=202 m) and half-wavelength (l=845 m) was measured in zone no. i, while the smallest chord-length (h=435 m) was in zone no. v (fig. 4). thus, in case of each parameters the difference in mean values is almost threefold (2.8-3.2). decreasing discharge resulted the development of misfit channels (zone no. i and v), which then reworked the material of the original channel. the mean half-wavelength of misfit paleo-channels is 228-340 m, while the mean chord-length is 147-229 m. the mean value of the radius of curvature is varying between 67106 m. values related to the original meanders are 2-4.5 times greater than that of the misfit bends (table 2). as according to gábris (1986) developed (β=1.11.4) and well-developed (β=1.4-3.5) meanders are the most appropriate for paleo-discharge calculations, the development phase of the bends was also calculated. concerning mean values two out of the nine meandering paleo-channel zones (no. xii and xiii) fall into the developed class, while the remaining seven zones are well-developed (table 3). for all zones the paleodischarge calculations were carried out using the mean horizontal channel parameters and the formerly created regional equations (sümeghy and kiss, 2011). the greatest mean bankfull discharge was calculated for paleo-channel zone no. ix (2655 m 3 /s). this value equals to the present day flood discharge (2400-3200 m 3 /s) of the tisza river (sándor, 2011) and slightly higher than the present day peak discharge (2420 m 3 /s) of the maros river (sipos, 2006). on the alluvial fan there are two other paleo-channels with bankfull discharges above 2000 m 3 /s (zone no. vi and xiii). four paleo-channels (no. iv, viii, xi and xii) have a mean bankfull discharge around 800-2000 m 3 /s, which is similar to the mean discharge of the tisza (800 m 3 /s, tímár, 2003). in zone no. i. original meanders could have four times greater bankfull discharge (493 m 3 /s) than younger, misfit channels (119 m 3 /s). the difference is even greater in case of zone no. fig. 3 cross-section of a braided channel in zone no. iii/b 16 sümeghy and kiss (2012) v., where the original discharge was ca. 508 m 3 /s, while the discharge of the misfit channel was only 27 m 3 /s. in these cases the earlier discharge of the paleo-channel zones is similar to the present-day bankfull discharge of the maros (680 m 3 /s, sipos, 2006) and lower than the mean discharge (600 m 3 /s) of the tisza (sándor, 2011). the bankfull discharge values of the misfit channels are close to the minimum discharge (31 m 3 /s) of the present day maros (sipos, 2006). slope conditions on the alluvial fan the height difference between the highest (103 m asl) and lowest (77 m asl) points of the alluvial fan is almost 30 m. the greatest slope was found in the central part of the fan (mean slope: 31.0 cm km -1 ), whilst slightly lower values were experienced in relation with its axial (23.8 cm km -1 ) and distal parts (24.9 cm km -1 , fig. 5). these parameters reflect the normal radial profile of an alluvial fan (rachocki, 1981) referring to coarse sediment deposition in the central zone of the alluvial fan (lecce, 1990). our aim was to find relationship between slope and channel pattern. the mean channel slope of meandering zones is 12.3 cm km -1 and of the braided channels is slightly higher, 17.6 cm km -1 . therefore, in the central part of the alluvial fan, which has the greatest surface slope, more braided channels or braided channel sections were formed than in the distal zone, which is characterised by mostly meandering channels. fig. 4 mean radius of curvature (rc,), half-wavelength (l) and chord-lendth (h) values of the meandering paleo-channel zones and the number of the analysed meanders table 3 the β-values (l/h) refereeing to the development phase of bends and the calculated mean bankfull discharges (qbf). discharge calculations were based on the radius of curvature (rc), half-wavelength (l), chord-length (h) zone β bankfull discharge (m 3 /s) rc l h qbf mean i. 1.68 649 423 405 493 1.46 225 70 61 119 iv. 1.80 1154 765 770 896 v. 2.35 673 570 281 508 1.55 58 13 10 27 vi. 1.73 2199 2087 2376 2220 viii. 1.40 1919 1076 1899 1631 ix. 1.80 2497 2462 3006 2655 xi. 1.58 1327 908 998 1078 xii. 1.30 1084 524 774 794 xiii. 1.29 2853 1474 2955 2427 morphological and hydrological characteristics of paleo-channels on the alluvial fan of the maros river, hungary 17 the entrenchment ratio of braided paleo-channels is between 1.0 and 1.4, while meandering paleo-channels are more incised (entrenchment ratio: 1.5-2.0), and in case of misfit paleo-channels the ratio is above 2.0. comparing the longitudinal slope profiles it becomes clear that in case of the braided paleo-channels longitudinal profiles of the floodplain and of the channel are almost parallel. in contrarily, the profiles of the meandering and misfit channels are convergent towards downstream. this can be explained by the tectonic uplift of the apex part of the alluvial fan or by an intensive accretion on the distal parts. the relationship between channel slope and the channel pattern changes is the most conspicuous in zone no ix. the channel pattern is braided in the axial part of the alluvial fan, meandering in the central part and in the distal part is braided again. these changes are reflected in channel slope as well. the channel slope is 22.4 cm km -1 in the eastern part, 19.2 cm km -1 in the meandering zone and 25.6 cm km -1 where the pattern changes and braided pattern appears again. the pattern change shows similar characteristics in other zones as well, thus the slope of braided channels is usually higher than that of the meandering ones. conclusions the surface of the hungarian part of the maros river alluvial fan was divided into 13 paleo-channel zones based on the channel pattern and morphometric parameters of the identified paleochannels. these zones showed braided, meandering, misfit and anastomosing patterns, though in some zones have a mixed character. braided paleo-channels are exceptionally large, their mean width varies between 1.4 and 3.7 km. they are bordered by 1-1.5 m high natural levees, and their channel is dissected by bars. the sinuosity of the braided channels is between 1.0 and 1.2, being under the threshold (1.5) of leopold and wolman (1957). the longitudinal profile of the floodplain and the braided paleo-channels are almost parallel (entrenchment ratio: 1.0 and 1.4). these channels mostly appear in the central zone of the alluvial fan, where the surface slope is the highest (its mean value is 31.0 cm km -1 and the maximum slope is 49.0 cm km -1 ), thus these channels could play important role in the sediment transportation and aggradation of the alluvial fan. similar braided fig. 5 slope calculations were made along radial lines following the paleo-channel zones in the axial, central and distal parts of the alluvial fan (cm km -1 ) 18 sümeghy and kiss (2012) pattern can not be found nowadays in the carpathian basin, but they were more abundant in former geological times. some braided paleo-channels were found on the romanian part of the maros’s alluvial fan with very similar channel parameters. braided paleo-channel generations were also identified in the middle tisza region (gábris et al., 2001) dating back to the late glacial maximum and to the younger dryas periods. however, on the alluvial fan of the hernád and sajó rivers braiding channel networks were not identified on the surface despite of the frequent channel changes (nagy and félegyházi, 2001; nagy, 2002). meandering channels on the alluvial fan have a highly variable size. values horizontal morphometric parameters were the lowest in the case of misfit channels (rc=67-106 m, l=228-340 m, h=147-229 m), thus they had the smallest bankfull discharge (27 and 119 m 3 /s). nevertheless, much larger meanders do also exist on the alluvial fan (rc=202-656 m, h=845-2394 and l=435-1402 m) with bankfull discharges between 490-2650 m 3 /s. the meandering paleo-channels are mostly located in the central and distal parts of the alluvial fan. their channel slope varies around 12 cm km -1 . the entrenchment ratio of meandering channels is between 1.5 and 2.0, referring to slight incision. floodplain and channel slopes are convergent downstream referring to tectonic uplift at the axial part of the alluvial fan or intensive downstream accumulation. according to the calculations of gábris (1986), the mean discharge of the száraz brook (in paleo-channel zone i) varied on the alluvial fan between 34 m 3 /s and 307 m 3 /s. in the present study the paleo-channel of the száraz brook was classified as a misfit channel. in zone no. i its mean bankfull discharge was 119 m 3 /s, while the older meandering paleo-channel, in which it was developed, had a ca. 500 m 3 /s mean bankfull discharge. comparing the calculated bankfull discharge to the present values of the tisza and maros we found that the largest meandering paleo-channels had bankfull discharges (2427-2655 m 3 /s) similar to the present-day peak discharge of the maros (1600-2500 m 3 /s, fiala et al., 2006) and the flood discharge of the tisza (2400-3200 m 3 /s, sándor, 2011). the discharges of medium sized meandering paleochannels (493-794 m 3 /s) are around the present day bankfull discharge of the maros (680 m 3 /s, sipos, 2004) and the mean discharge of the tisza (800 m 3 /s, tímár, 2003). however, the smaller, misfit paleo-channels transported only 27-119 m 3 /s water, comparable to the minimum discharge of the maros (31 m 3 /s, sipos, 2006). acknowledgements the research was supported by the huro/0901/266/2.2.2 cross-border project and the 100761 otka research grant. references andó, m. 1969. körös-maros közi síkság. in pécsi, m. 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(edts.): developments and applications of geomorphology. springer-verlag. berlin heidelberg, 343–367. identification of riparian vegetation types with machine learning based on lidar point-cloud made along the lower tisza’s floodplain journal of environmental geography 13 (1–2), 53–61. doi: 10.2478/jengeo-2020-0006 issn 2060-467x identification of riparian vegetation types with machine learning based on lidar point-cloud made along the lower tisza’s floodplain istván fehérváry1*, tímea kiss2 1lower tisza hydrological directorate, stefánia 4, 6720 szeged, hungary 2university of szeged, department of physical geography and geoinformatics, egyetem str. 2-6, 6722 szeged, hungary *corresponding author, e-mail: fehervaryi@ativizig.hu research article, received 7 april 2020, accepted 5 may 2020 abstract the very dense floodplain vegetation on the artificially confined floodplains results in decreased flood conveyance, thus increase in flood levels and flood hazard. therefore, proper floodplain management is needed, which must be supported by vegetation assessment studies. the aims of the paper are to introduce the method and the results of riparian vegetation classification of a floodplain area along the lower tisza (hungary) based on automatized acquisition of airborne lidar survey. in the study area 15x15 m large training plots (voxels) were selected, and the statistical parameters of their lidar point clouds were determined. applying an automatized parameter selection and 10-fold cross-validation he most suitable decision tree was selected, and following a series of classification steps the training plots were classified. based on the decision tree all the pixels of the entire study area were analysed and their vegetation types were determined. the classification was validated by field survey. on the studied floodplain area the accuracy of the classification was 83%. keywords: airborne lidar, scikit-learn, gini impurity, decision tree, riparian forest, introduction during the last one and half century several environmental effects (e.g. climate change, land cover alterations) affected the floodplains and river channels altering their characteristics. however, these semi-natural effects were exceeded by the consequences of various river engineering works: the channel and floodplain regulations works altered the hydrological processes, and as one of the consequences the riparian vegetation changed too. the riparian vegetation highly influences the channel-floodplain connections. for example, the vegetation along a river stabilises the banks (abernethy and rutherfurd, 1998), or decreases the overbank flow velocities (kiss et al., 2019a). along the river-banks the density of vegetation primarily influences the development of natural levees (nagy et al., 2018), whilst in the distal floodplain areas the vegetation influences the flood flow directions and velocities (rátky and farkas, 2003; zellei and sziebert, 2003; brooks, 2005; corenblit et al., 2007; geerling et al., 2008), thus the vertical aggradation pattern (steiger et al., 2001; kiss and sándor, 2009). these processes are related to the roughness controlling function of the vegetation, which influences the flood stages too (jalonen et al., 2015; kiss et al., 2019a). the highest peak flood level on record was set in 1970 along the tisza river, hungary, however along the lower tisza this record was overprinted in 2000 and also in 2006 by higher stages of 80 cm (kiss et al., 2019b), while the discharge of these record floods were lower than in 1970 (kovács and váriné szöllősi, 2003). these hydrological changes draw attention to flood conductivity decline of the floodplain: nowadays only 13% of the flood discharge is drained on the floodplain while it was 23% in 1970 (kovács and váriné szöllősi, 2003). it could be partly related to the very dense floodplain vegetation, therefore proper floodplain management is needed, which must be supported by vegetation assessment studies. their first step should be the identification of riparian vegetation types; therefore, our aim is to apply the latest methods for this identification using automatized acquisition of lidar survey data. lately several researches relied on the statistical analysis of point-clouds of lidar surveys to identify vegetation characteristics and types. most of these researches were made in the field of forestry or ecology. for example, hudak et al. (2008) identified various tree species in forest patches based on various statistical parameters of the lidar points representing the canopy. heurich and thoma (2008) did similar research, but they measured some dendrological parameters too (e.g. tree height, canopy width) based on lidar data. naesset et al. (2004) combined airborne and terrestrial lidar data to calculate the main parameters (i.e. number of stems, volume of harvestable wood) of forest units. jung et al. (2011) calculated not only the parameters of trees (i.e. tree height, lower canopy height, canopy volume, stem diameter), but also the temporal changes between two survey campaigns including both lidar technologies. though these researches slightly differ in the identification of vegetation types and in defining their parameters, it could be concluded, that some high54 fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. resolution parameters could be applied just on small areas or on individual level, while the measurements on larger areas have limited resolution and less accuracy. during the last years the lidar based vegetation analysis has been applied also in hydrological studies. for example, vetter et al. (2011) determined the vegetation roughness based on the spatial connection of voxels (3d pixels) and the rate of reflections, using an airborne lidar survey with very high point density (>25 point/m2). the resulted vegetation density values were applied in a 2d hydraulic model, and the derived hydrological data were compared to modelled data based on classical land-use category maps. vetter et al. (2011) concluded, that the lidar based modelling gave much more reliable results, as the hydrological data were closer to the actually measured ones. similarly, manners et al. (2011) determined the role of tamarix bushes in vegetation roughness using terrestrial lidar survey. during the late 20th century forest became the dominant land cover type along the tisza river and invasive species became widespread in the undergrowth, thus the vegetation roughness of the floodplain drastically increased, as it was indicated by point-based classical vegetation surveys (kiss et al., 2019a). as the high vegetation roughness fundamentally decreases the overbank flow velocities and increases flood peak levels, high-resolution and up-to-date data would be needed for precise flood modelling. however, no such a dataset exists. therefore, our aims are to introduce the method and the results of riparian vegetation classification, based on automatized acquisition of airborne lidar survey. within this article our goals are to describe the detailed methodology of the automatized classification, to classify the vegetation on a study area located along the lower tisza river, and to evaluate the feasibility of the method. study area the research was conducted on a 3 km2-large floodplain area of the lower tisza (197-194 fkm) between the settlements of algyő and szeged (fig. 1). the floodplain is artificially confined by artificial embankments to 800 m; and the river channel is 130 m wide in average. at algyő gauging station the greatest flood-stage was at 84.65 m asl, while the lowest stage was measured at 71.55 m asl, thus the absolute change in water level is ca. 13 m. the flooding of the floodplain starts when the water is at 80 m asl, and up to 5-6 m deep water column develops over the floodplain at the time of record floods. the slope of the water is very low (2.9 cm/km), therefore the overbank flow velocity is also low (max. 0.1-0.2 m/s). in the mid-19th century the river regulation works (e.g. artificial cut-offs, building artificial levees) resulted in considerable land-use changes of the floodplain (kiss et al. 2019a). at the beginning of the 20th century the former wetlands were replaced by meadows, pastures and plough fields, while the proportion of forests remained low. however, as the result of intensive afforestation in the 1970-80s the proportion of forests increased above 70% in the 1980s, and nowadays it is above 80%. these landcover changes resulted in fourfold increase in vegetation roughness (from 0.02 to 0.08), which is even higher (0.13) if the dense stands of invasive species in forest and on fallow lands are considered. among the invasive species the amorpha fruticosa is the most abundant (11%), which creates impenetrable shrubbery. according to our latest fig. 1 the study area is located along the lower tisza, north of the city of szeged fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. 55 results its thickets decrease the flood flow velocity to one third, creating 20-30 cm increase in flood levels at our study area (kiss et al., 2019a). data source the analysed point cloud is based on a lidar (fullwaveform) survey was made at the early spring of 2015 during low stage of the tisza river. there were no leaves on the trees, thus the canopy structure of the individual trees is nicely visible on the survey. simultaneously to the lidar survey an ortho-photo was also made with 10 cm resolution. the study area is represented by 22.5 million reflected points on the airborne lidar survey, which are stored in eight .las files. the lowest points represent the bank of the river at the actual water-surface (at 75.1 m asl), while the highest indicate the topmost points of the 30-35 m high trees. the water surfaces (e.g. open water, wetlands) do not reflect the lidar beams, therefore, these areas were excluded from the analysis. after this exclusion the point-density of the study area is 9 point/m2, thus it could be considered as suitable for the analysis, as according to laes et al. (2008) the analysis of forests requires at least 4 point/m2 point-density. only 3% of the study area does not fulfil this requirement, thus the quality of the survey was good for further analysis. the digital elevation model (dem) made of the lidar data has 0.5 m resolution. methods for the analysis the fusion 3.8 and arcmap10.6.1 software were used, while the algorithm of the vegetation classification (decision tree) was written in python using the scikit-learn (0.22.1) library (see pedregosa et al., 2011). the decision tree were generated with decesiontreeclassifier class-based on the gini impurity (grabmeier and lambe 2007) which is in the sklearn.tree module. to find the most ideal and relevant parameters for the decision tree algorithm, the gridsearchcv class was applied using k-fold cross validation method. the detailed description of the decision tree can be found in the results 5.1. chapter. based on the results of the decision tree the vegetation types of all pixels in the study area were determined automatically, and finally the results were checked and validated based on a field survey. data preparation as the dem was in a .flt format, it had to be converted to .dtm, thus it could be used in the fusion software for further calculations. as a first step the dem was exported in arcmap software to .ascii format using the rastertoascii tool, then in fusion it was converted to .dtm applying the ascii2dtm tool. in the next step the quality assessment of the lidar point-clouds stored in .las files had to be done, analysing the extreme values and the number of reflections. the quality check was made in fusion software applying the catalog tool. as a result, the software made a quality report of each .las file, including the number of points, their minimum and maximum heights, and the point-density (point/voxel). using the filterdata tool the extreme values were deleted from the file. determine the spatial resolution to select the most suitable spatial resolution is crucial point of the research. if it is too high, the point cloud will be over dissected, and the typical parameters of a given vegetation type could not be distinguished. however, if the spatial resolution is too low, the spatial differences could disappear and there will be a greater chance to have mixed classes. laes et al. (2008) suggested, that the spatial resolution should be fitted to the mean canopy width. therefore, in the study area 15x15 m spatial resolution was selected, thus the point-cloud was split into voxels with 15x15 m cell-size, and the height of the voxels was determined by the highest point of the vegetation. calculation of statistical parameters (metrics) in the following step the statistical parameters of the lidar point-clouds representing the vegetation were calculated applying 15 m resolution for the voxels. the calculation was made by fusion software using its gridmetrics tool. the input data included the filtered and quality-checked point-cloud and the dem in .dtm format. in the programme a heightbreak could be set, thus the program could recalculate some statistical parameters of the voxels split into two parts by a given elevation (for example the proportion of reflected points above a given height). in our case we had selected 6.0 m as a height brake, and the voxel parameters for the forests were calculated above this value. this value was selected because (i) the bushes (especially invasives) are never taller than 6 m, and we wanted to classify the vegetation regardless of the rate of invasives in the underwood; and (ii) this is the limit of the overbank flood height. the calculated statistical parameters of each voxel were stored in .csv files. the programme provided 74 parameters for each voxel. not all these parameters are introduced in this paper (following mcgaughey 2018), only those, which were used to classify the vegetation types of the study area applying the decision tree. the canopy relief ratio (crr) was calculated as the ratio of the difference between the mean and minimum heights and the maximum and minimum height of the points of a given voxel [(mean-min)/(max-min)]. thus, the greater the difference is between the mean and maximum values, the crr is lower. this parameter refers to the spreading of the canopy: in case of large and wide canopy the mean and maximum values have relatively small differences. at the study area the old white poplars have huge canopy with 0.2-0.3 crr values, whereas the young planted black poplars have slender canopy with 0.03-0.04 crr values. the open surfaces (e.g. short grasslands) have the highest crr values (0.4-0.5), as their mean and the maximum height values are almost similar. the standard deviation of the height values of a voxel (elev_std) refers to the diversity of the points, thus to the vertical dissection and density of the canopy: the flat and at a given elevation dense canopy is reflected by almost homogenous point-cloud at a given elevation of 56 fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. the voxel, thus it is characterised by low standard deviation. for example, in the study area the open surfaces, where almost every point represents the land or the grass, the standard deviation is 0.03 m, while in case of the riparian willow stands the standard deviation is higher by two orders (3-4 m). the greatest standard deviation (8-10 m) was measured at the populus alba stands which has variegated canopy. the 99th percentile value for a voxel (elev_p99) refers to that elevation, where the height values reach the 99% from the ground, thus it refers almost to the maximum height of the voxel. for its calculation the height values of the point-cloud of a voxel are ordered, and that value is selected which represents the 99% of the dataset. for example, on the study area this value is much lower for the willow stands (~15 m) than for the white poplar trees (~25 m). the 95th percentile value for a voxel (elev_p95) refers to that elevation, where the height values reach the 95% from the ground. it is calculated similarly as the previous parameter (elev_p99). this parameter is useful during the calculations, because it is a good indication of the maximum height of the vegetation, however it does not contain points with survey errors. skewness of the heights for the points in the voxel (elev_skewness) provides some indication of how asymmetric the distribution of the values is. in case of symmetric (standard normal) distribution the skewness is zero. the skewness is influenced by abundant and extreme values: if they are at low values, the n the skewness will be negative, while in case of higher values it will be positive. in the study area high (4 -6) and positive skewness characterises the young poplar plantations, and the lonely and slim trees: in their case the canopy is not perfectly closed, therefore high proportions of the reflected points are from the ground or from the top of the canopy. in case of grasslands the skewness is low (0.1-0.4), as no extreme values are present, the reflected points originate from almost a flat surface. selection of training-plots and definitions of vegetation types before the training plots were selected, the main vegetation types had to be determined at the study area. the following categories were identified based on our preliminary field survey and the forestry webmap of hungary (https://erdoterkep.nebih.gov.hu) (1): open surface, amorpha thicket, young poplar plantation, poplar plantation, riparian willow forest, and riparian poplar forest with populus alba. based on our field-survey and the available orthophoto we had selected 15x15 cell-sized pixels with homogenous vegetation as training plots. they were selected for each vegetation types, at least 40 -50 cells per type. during the selection of training plots we aimed to select homogenous pixels, thus the pixel should not be affected by side effects of other vegetation types. the selection of the training plots was supported by the ortho-photo providing idea on the character of the cell, while the point-cloud of the voxel gave idea about the height conditions of the vegetation and the shape of the canopy (fig. 2). fig. 2 various vegetation types represented by the vertical view of the lidar point-cloud, and its appearance on the ortho-photo https://erdoterkep.nebih.gov.hu/ fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. 57 grasslands and open surfaces are mostly located on the artificial levees. the lidar survey was made in early spring when the grass was very short and dead, therefore the reflected points actually represent the land surface, therefore here the height of the vegetation is almost 0 m. the dense amorpha thickets have height points at 1-6 m, the top of the canopy is almost flat, and great proportion of the lidar point-cloud is at the upper part of the canopy. the riparian willow forests are high (16-20 m), and on the ortho-photo the almost bunding willowbranches have brownish-orange colour. the poplar plantations are planted in rows, thus the skewness of their point-cloud is high, as lots of points are reflected from the ground and also from the top of the canopy. on the lidar point-clouds their canopy structure is quite specific, as their branches are thin, most of the points are around the stem, and on the ortho-photo the top of these plantations is quite homogenous. within the poplar plantations we distinguished the group of young poplar plantations. their trees are shorter (>5.6 m), and more points are reflected from the ground due to their undeveloped canopy. this forest type also includes lonely trees with sparse bushes. the riparian poplar forest patches are characterised by tall and easily distinguishable populus alba trees. the white poplar has greyish-white branches on the ortho-photo, and it has very special canopy structure both on the ortho-photo and the lidar point-cloud (fig. 2). creating the decision tree the statistical parameters of the training plots were saved in a .csv file. in this file the names of vegetation types and all of the statistical parameters were given. the next step was the parametrisation of the decision tree algorithm. the decision tree classifies the elements – in our case the attributes of the voxels – based on the series of classification steps, aiming to have the most homogenous classes. the selection of attributes and the thresholds between the classes are based on a calculation algorithm. in our case the threshold values were based on the gini impurity, because it could be run faster than the entropy based calculations, besides, there is no qualitative difference between the accuracy of these classifications. the gini impurity refers to the probability of the classification of an element to a wrong class (grabmeier and lambe, 2007). if its value is zero, it means that the given selection criteria perfectly divided a class from the main population, while 1.0 refers to a totally diverse class. the setting of the parameters of the decision tree was made automatically applying the gridsearchcv module, considering the (i) maximum depth of the decision tree referring to the number of decision levels; (ii) the minimum element number of the leaves; and (iii) the minimum element number for split. to precisely determine the above mentioned settings of the decision tree, each setting was set to an interval (e.g. decision tree depth: 1-10; minimum element number of leaves: 2-10; minimum split: 2-20), and finally best setting combination was selected, which resulted in the most precise decision tree. to check the accuracy of the decision tree algorithm, a cross-validation method was applied, which is very common at automatized learning technologies. we had selected the method of 10-fold cross-validation. as a first step the dataset (training plot voxels) were divided to 10 groups, and one of them was selected for validation by the algorithm. the cross-validation lasts for 10 iterations, until every group will be used exactly once as a training set (bengio and grandvalet 2004). to estimate the accuracy, the average of 10 results were needed. the advantage of this kind of cross-validation is that each point (voxel) of the dataset will be used for automatic learning and for validation too, however its disadvantage is that it is a quite long process, as in our case the automatic learning was repeated 10 times. the accuracy of the final classification based on the decision tree is expressed in percentage, referring to the rate of well-classified elements, though this value does not refer to the efficiency of the classification. during the application of the decision tree two kind of methodological mistakes could be made. in the first case the classification process and the applied thresholds do not determine the classes homogenously, thus the decision tree will have low accuracy and it is underfit, however if there are lots of data and several parameters, this case is quite rare. much more often the decision tree will be overfit, thus the selection criteria will be too specific and valid just for some elements of the dataset. in this case the accuracy is very high (>95%), however the decision tree could not be applied on other datasets (schaffer 1993). the aim of the automatized parameter selection and of the 10-fold cross-validation was to find the most suitable decision tree, which eliminates the errors of the overfitting. during the cross-validation runs it became obvious, that the decision tree is greatly influenced by its depth. our results suggest, that if the depth of the decision tree is greater than 4, the accuracy won’t be considerable better, however the risk of overfitting increases (fig. 3). therefore, the depth of decision tree was determined to be 4. the minimum element number and minimum split number was determined to be 2. in this way the accuracy of the created decision tree based on the 10-fold cross-validation was 92%. fig. 3 relationship between the depth of the decision tree and the accuracy of the classification 58 fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. fitting the decision tree to the entire study area and its validation the decision tree was created based on training plots. in the next step, based on the decision tree all the 11656 pixels of the study area were analysed and their vegetation types were determined. the result and precision of the automatized classification were determined by fieldsurvey. for the field validation aerial photos made by dji phantom iii pro drone were taken on 72 cells. the survey was made at 30-60 m height from orthogonal position (applying 90º camera axis). on these low-aerial photos the vegetation types of the cells were identified by expert judgement. the geo-coordinates of the photos were extracted; thus the identified vegetation types could be compared to the automatized classification of the same cell. the results of the comparison were evaluated applying a confusion matrix. the titles of columns and rows in the matrix refer to the vegetation categories. in the main diagonal line, the numbers refer to the proportion of precisely classified cells, while the other cells refer to the proportion of false vegetation classes. results the decision tree the decision tree automatically selected the parameters of the voxels (see 4.5. chapter) for the identification of vegetation types (see 4.3. chapter). first, the young poplar plantations were selected based on crr≤0.039 criteria. this parameter well sunders the young and short poplar trees with undeveloped canopy from the higher trees with more complex canopy and from the grassland/open surfaces. the next step followed the false (no-)branch of the decision tree (crr≥0.039). here, based on the standard deviation of the voxel’s point-cloud the amorpha thickets and the grassland/open surfaces were identified. the two vegetation classes could be divided based on their height (elev_p99). to identify the grassland/open surfaces the voxels had to be fulfil the following criteria: crr≥0.039 and elev_std≤1.783, and elev_p99≤2.119. the amorpha thickets were identified by crr≥0.039 and elev_std≤1.783, and elev_p99>2.119. the gini impurity (0.0) of these three categories reflects that they were identified with the greatest accuracy (fig. 4.). on the false (no-)branch of the standard deviation (elev_std≥1.783) of the decision tree the older poplar plantations, the riparian poplar forests and riparian willow forests remained. on the floodplain the riparian poplar forests are characterised by tall populus alba trees, thus they could be selected based on their height conditions (elev_p95>17.987). however, this selection criterion is not totally clear, as some voxels with tall planted poplars also fall into this class. the natural and planted poplar forest could be divided based on the crr parameter: the poplar plantations have less complex canopy than of the natural poplars, therefore the plantations have smaller crr values, thus their selection criterion is crr≤0.103. the riparian poplar forests were selected following elev_std>1.783 and elev_p95>17.987 and crr>0.103. some of the poplar plantation’s cells (with older and higher trees) also fall into this class, only their crr values differed (elev_std≥1.783 and elev_p95>17.987 and 0.039<crr≤0.103). based on the tests the tall (≤18 m) and old poplar plantations were clearly separated (gini impurity = 0.0) from the riparian poplar forests with populus alba (fig. 4.). fig. 4 decision tree built up based on training plots of the study area. this decision tree was applied to classify the vegetation types on the entire study area fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. 59 on the true branch of the elev≤17.987 criteria the riparian willow forests and the less-old and shorter poplar plantations remained. the planted poplars are slim with column-like canopy, and the reflected points from the ground between the tree-rows result in asymmetric distribution of the height points. as the skewness reflects well the asymmetric distribution of the values, the criteria of elev_skewness> 2.376 were applied to identify the two vegetation classes. the identification of the poplar plantations followed the criteria of crr>0.039 and elev_std>1.783 and elev_p95≤17.987 and elev_skewness>2.376. the parameters of the riparian willow forests are almost the same as of poplar plantations, only their skewness is different: crr>0.039 and elev_std>1.783 and elev_p95≤17.987 and elev_skewness≤2.376. however, at the study site these vegetation types could be mixed even within a 15x15 m cell, which influences the accuracy of the classification, however, the identification of the classes was still effective (gini impurity < 0.16). vegetation types of the study area based on the automatized classification the decision tree created on training plots were applied on the entire, 3 km2-large study area. the vegetation types of 11656 voxels were identified, and the land-cover map of the area was created (fig. 5.). in the study area the most abundant land-cover category (fig. 6.) is riparian willow forest (30%, 80 ha). willow patches appear mostly in deeper lying areas, like in front of the artificial levees and on the edges of claypits. the grasslands/open surfaces (24%, 63 ha) mainly cover the artificial levees, but in this category also some plough-fields are and clay-pits, where the dead herbaceous vegetation covers the surface like a mat. planted poplar forests (15%, 40 ha) appear in great units. from the point-of view of flood conductivity the proportion of amorpha thickets (10%, 25 ha) is crucial. they usually appear along the edges of other vegetation types and on the fallow lands. in the study area the smallest area is occupied by young poplar plantations (9%, 23 ha), but this category contains those patches as well, where young trees are mixed with bushes, but they do not create dense stands. validation of the results the accuracy of the automatized classification was determined by comparing its results to field-surveys on 72 randomly selected cells. the results are summarised in a confusion matrix (table 1.). the accuracy of the automatized vegetation classification based on the decision tree algorithm was 83%. the open surfaces were classified with the lowest accuracy (75%). some open surfaces were classified by fig. 5 ortho-photo of the study area (a) and the automatized vegetation type map of the same area based on the classes of the decision tree (b) 60 fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. fig. 6 proportion of the different vegetation types in the study area the algorithm as amorpha ticket (8% of the cases) or as young poplar plantation (17%). most of these misidentifications occurred at the boundary between the grass-covered artificial levee and the arboreous vegetation, where many sprouts and low branches stretches over the grassland. the identification accuracy of the riparian willow forests is 85 %, in reality, the misidentified patches belong to poplar plantations (5%), amorpha thickets (5%) or riparian poplar forests (5%). this error has multiple sources: (i) between the lidar and the field surveys some forests were cleared and the clearances were colonised by amorpha; (ii) these vegetation types could be mixed on a 15x15 m-sized cell; (iii) depending on the age of the forest patch the various vegetation types could have similar height and even similar canopy size. the amorpha thickets were the most accurately (92%) classified by the algorithm. only 8% of them were mis-classified, and got to the class of riparian willow forest. however, this error is not considerable, as it was detected on cells where the willow forest was highly invaded by amorpha. the identification accuracy of riparian poplar forest was 83%, as some of their patches were identified as planted poplar (8%) and as young poplar plantation (8%). these mis-identifications were in table 1 confusion matrix summarizing the validation results. green colour indicates % of well -classified voxels (%), red colours refer to percent of unwell-classified voxels based on decision tree open surface riparian willow amorpha thicket riparian poplar forest young poplar plantation poplar plantation b a se d o n f ie ld w o r k open surface 0.75 0.00 0.08 0.00 0.17 0.00 riparian willow 0.00 0.84 0.05 0.05 0.00 0.05 amorpha thicket 0.00 0.08 0.92 0.00 0.00 0.00 riparian poplar forest 0.00 0.00 0.00 0.83 0.08 0.08 young poplar plantation 0.00 0.00 0.17 0.00 0.83 0.00 poplar plantation 0.00 0.00 0.00 0.18 0.00 0.82 fig. 7 vegetation types based on drone photos. a: open surface, b: amorpha thicket, c: young poplar plantation, d: poplar plantation, e: riparian willow forest, and f: riparian poplar forest with populus alba fehérváry and kiss 2020 / journal of environmental geography 13 (1–2), 53–61. 61 those cells, where the natural poplars were mixed to planted poplars. the young poplar plantations were identified by 83% accuracy too, as some of the cells were identified by the algorithm as amorpha thickets. it could be explained by the fact, that very young plantations have similar height and density conditions as the thickets, besides, if the plantation is not managed properly, amorpha could invade them very quickly. the accuracy of poplar plantations was 82%, as the greatest errors occurred when the algorithm classified them as riparian poplar forests. it could be explained by the similar height of old plantations and younger populus alba trees. conclusion the applied automatized machine learning-based classification is suitable to identify various vegetation types based on airborne lidar survey data. not only land-cover types (e.g. forest), but various vegetation and forest types could be identified using the method, which has acceptable accuracy. for example, on the studied floodplain area the accuracy of the classification was 83% (based on 72 observation). the data acquisition of lidar surveys combined to automatized machine learning enables us to precisely, effectively and quickly map the vegetation even on large, remote or impenetrable areas. in case of repeated surveys, the algorithm easily could be trained to the new dataset, thus the temporal changes in vegetation could be quickly and automatically detected, which is a great advantage for both researchers, stakeholders and decision makers. the application of the resulted vegetation type map is quite wide. for example, it could be used by hydrologists, as up-to-date vegetation maps are needed during the planning and maintenance of flood-conductivity zones, or during the modelling of floods, when up-to-date data are needed on vegetation roughness to determine the manning coefficient. in forestry these lidar-based vegetation maps could be used too, as the statistical parameters of forests could be calculated, and forest clearance plans could be supported. acknowledgement the lidar data are owned and provided by the ativizig (lower tisza hydrological directorate). the research was supported by the hungarian research fund (otka 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(szerk.): elemző és módszertani tanulmányok az 1998-2001. évi árés belvizekről. vízügyi közlemények különszám 4, 133–144. introduction study area data source methods data preparation determine the spatial resolution calculation of statistical parameters (metrics) selection of training-plots and definitions of vegetation types creating the decision tree fitting the decision tree to the entire study area and its validation results the decision tree vegetation types of the study area based on the automatized classification validation of the results conclusion acknowledgement references characteristics of post socialist spatial development of the functional urban area of veszprém, hungary journal of environmental geography 12 (3–4), 33–43. doi: 10.2478/jengeo-2019-0010 issn 2060-467x characteristics of post socialist spatial development of the functional urban area of veszprém, hungary vera iváncsics*, krisztina filepné kovács department of landscape planning and regional development, faculty of landscape architecture and urbanism, szent istván university, villányi út 35-43, k building, h-1118 budapest, hungary *corresponding author, e-mail: ivancsics.vera@phd.uni-szie.hu research article, received 7 october 2019, accepted 19 november 2019 abstract the post-socialist era resulted remarkable changes in urban landscape in eastern europe and in hungary. the special circumstances caused moderate level of urbanisation and special patterns of urban sprawl, traceable in land use changes. the urban sprawl and suburbanisation became an important trend around smaller hungarian cities as well. regulators are eager to rule the evolution of spaces, however, it is hard to control all aspects of land use. the research presented in this paper shows the dynamics of new artificial areas with the help of land use changes from the corine database for the functional urban area around veszprém and attempts to find the most important policy responses to the growing artificial surfaces after transition. the research questions are: what are the most important trends in changing in-built areas in a small city after the transition? what kind of new artificial areas appeared and where are they situated? were the land use plans and nature protection effective tools for manage urban sprawl? with the help of corine land use changes between 1990-2018 the most important spatial changes are shown, and the different peri-urban areas are compared around the core town. attention is drawn to the importance of regulation for sustainable land use and protection of resources. it also highlights the importance of the regulatory power of municipalities. changes in the environment of veszprém may give inspiration for the rethinking the relationship of urban-rural, and catchment area and core town. keywords: land use analyses, urban sprawl, veszprém, post-socialist urban development, regulation introduction one of the commonly mentioned challenges of the future is urban sprawl (eea, 2016) and land use as the essential factor of it (espon, 2006; eea, 2007). there is also a growing body of literature that recognizes the importance of the most influenced territories: role of the central city and its settlement network, the periphery, edge, peri urban territories (meeus and gulinck, 2008; csemez, 2008; piorr et al., 2011; szirmai, 2011; woltjer, 2014; oueslati, 2015). the spatial context of urban sprawl is also highlighted and researched by international bodies like oecd and the eu and the definitions of functional urban area (fua) (oecd, 2012) or settlement group municipalities (ksh, 2014) are integrated into the international and national statistical systems as well. studies also attempt to find regulatory or other assets to control or manage the growth of urban areas (allen, 2003; ros-tonen, 2015; geneletti et al., 2017) and suggests sustainable development, the management of urban sprawl and its consequences and also foster the densification of artificial surfaces (artmann et al., 2019). the special aspects of urban development in eastern europe – the semi-peripheral situation, the slow transition of society based on agricultural to industrial production, the changing regulatory system after socialism, postponed urbanisation process during socialism, and despite of intensive suburbanization after 1990, a moderate level of urbanisation (enyedi, 1988; beluszky and győri, 2005; enyedi, 2012;) – give additional motivation to researchers and planners to highlight the causes and the possibilities to cope with urban sprawl. several studies focus on the importance of land use changes of cities and towns as well in post socialist countries (for example lincaru et al., 2016; grigorescu and kucsicsa, 2017 in romania; roose et al., 2013 in estonia; slaev and kovachev, 2014 in bulgaria; zivanovic-miljkovic et al., 2012 in serbia) and most of them urges the importance of regulatory tools to manage land use changes in peri-urban areas. hungary is also affected by increase of artificial areas, however in several regions the population of urban fabric decreases (hennig et al., 2015). several researches showed the tendencies and differences within hungary (for example ladányi and szelényi, 1997; bajmócy, 2001; timár, 2005) as well as in small cities like győr, pécs, miskolc (lux, 2014, hardi, 2012; somlyódyné pfeil, 2012), szeged (mucsi, 2011), kecskemét (ricz et al., 2009), nyíregyháza (kókai, 2006), most of all focus on socio-economic changes and consequences, but not land use changes. although the trends are well known, the hungarian spatial planning could not find satisfactory answer to manage urban sprawl and negative tendencies of increasing land consumption. in our research we explore the trends of spatial growth of a smaller hungarian town, veszprém and its functional urban area. in spite of the fact that the importance of agglomeration is highlighted in towns with more then 100 000 inhabitants in literature, the agglomerational potential of the town is underlined. with its almost 60 000 inhabitants it has regional importance in the transdanubian 34 iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. region of hungary (koós, 2010; hardi, 2015), but no such case study focusing on veszprém and its surroundings has been published yet. our research area was delineated into 3 characteristic parts: an outer fringe, an inner fringe and the core town according to the international and also broader delineation of catchment settlements fua, and the national, more focused agglomeration arena settlement groups. land use changes were analysed based on corine database between 1990 and 2018, in 4 periods. results were also compared to the former land use management plans on country and on municipality level (in the case of veszprém). study area the area at the central-transdanubian region in hungary (fig. 1), along the lake balaton highlands and bakony mountain has diverse natural and landscape features: topography, natural environment is characteristic and protected. the temperate climate is mild, becomes warmer closer to the lake balaton (balaton-riviera). the annual precipitation varies between 500-800 mm. sedimentary and volcanic aquifers are both found in the fragmented landscape. in addition to the diverse natural values of the area it is also an important cultural landscape. in addition to management based on landscape characteristics (vineyards or cultivation of herbs) its ethnological values are unique (dövényi, 2010). the land use patterns are also diverse here. several settlements have agricultural or forestry tradition (szentgál, zirc) however, industrialisation also caused significant changes (balatonfűzfő, papkeszi). in addition, a military training field is also located here, with regular international exercises. as the area partly belongs to the preferred holiday destination and is a popular target of investments in recent years, it's natural values and landscape management are threatened. therefore, developments are particularly important in accordance with the outstanding landscape system and values. the centre of the study area is veszprém town, which is approx. 12 690 ha and a specific topographic location thanks to the vicinity of lake balaton, foot of bakony mountain and séd creek. it is the pole town of its surrounding fua (131 310 ha) and also its settlement group (53 932 ha). the town’s former administrative and educational character has changed. new technical university was founded, and several industrial sites were opened, the population grew from about 20 500 (1949) to about 63 000 (1990) during the socialist era. now veszprém has almost 60 000 (2018) inhabitants (teir.hu). the transition brought a less intensive development, but today veszprém is an economical focus point of western hungary thanks to several companies, which have chosen veszprém as new location. methods in our study the administrative area of veszprém and its surrounding – the settlement group (defined by ksh, 2014) and functional urban area (fua) (based on the urban atlas 2012) were analysed (fig.1). using the corine land use maps (clc changes layer) from 19902000, 2000-2006, 2006-2012 and 2012-2018 the land use changes have been calculated and visualized for the study area in geographical information systems (gis) – arcmap software 10.2.2. the categories defined on the basis of corine nomenclature (table 1) show the trend of the change. if the changes stayed within the category of three main land use pattern (artificial, agricultural and natural) it was identified as unchanged and was not highlighted during the analyses. however, the scale of the urban atlas would mean a better basis for analyses, it is fig.1 analysed areas: veszprém – core town, settlement group– inner fringe and fua fringe– outer fringe on google earth view iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. 35 available only for the year of 2012. that is why the urban atlas was used for visualisation of artificial surfaces (code begins with 1). the extent (in ha) was calculated with the help of arcmap software. excel software was used for further calculation of the ratio of the changed areas. to evaluate the relation of the land use changes and regulatory maps manual comparison was used, because the regulatory maps were in raster dataset available. furthermore, after manual check of each change of artificial land use in google earth and in actual land use maps of municipalities some corrections were needed because of the marked construction sites. for example, the polygon eu-176485 marked a construction site in the year of 2000 transformed to urban fabric for 2018. during the analyses the current or planned (in land use maps) state was taken into account. according to these categories the spatial distribution of the land use system (area of the municipalities of functional urban area, fua; settlement group municipalities and central town) was analysed and the most important tendencies between 1990 and 2018 were identified. with the use of this method the urban sprawl around veszprém was shown. results in present study the land use changes were analysed for the area of fua, settlement group of veszprém and administrative area of veszprém. changes of fua (outer) fringe (fua without settlement group area) and settlement group (inner) fringe (settlement group without the core town, veszprém) were also described. the ratio of different land use categories most significant changes described between 1990 and 2000, with about 5500 ha in fua and 785 ha in veszprém, but more than 90% of all changes stayed within the land use category, defined as unchanged. during this period the tendencies show similarity in the core town and its broader neighbourhood. the increase of natural and artificial areas is almost balanced, the new areas occupied former agricultural areas in the fua. in parallel in the fringe of the settlement group the artificial surfaces show higher increase. important fact is, that without the core town there were no change in natural areas within the settlement group (inner fringe), however in the outer fringe there were 167 ha table 1 the applied land use categories of the analyses, based on corine nomenclature code corine nomenclature simplification and terms in the research class 1 class 2 class 3 (relevant within artificial surfaces) main categories further categories 1.1.1 artificial surfaces urban fabric continuous urban fabric artificial surfaces urban fabric 1.1.2 discontinuous urban fabric 1.2.1 industrial, commercial and transport units industrial and commercial units industrial and commercial units 1.2.2 road and rail network and associated lands transport units 1.2.3 port areas 1.2.4 airports 1.3.1 mine, dump and construction sites mineral extraction sites mine, dump and construction sites (abbr. mine sites) 1.3.2 dump sites 1.3.3 construction sites 1.4.1 artificial, non-agricultural vegetated area green urban areas artificial, non-agricultural vegetated area (abbr. urban green areas) 1.4.2 sport and leisure facilities 2.1 agricultural areas arable land … agricultural areas 2.2 permanent corps … 2.3 pastures … 2.4 heterogenous agricultural areas … 3.1 forest and semi natural areas forests … natural, semi natural areas (abbr. natural areas) 3.2 scrubs and/or herbaceous vegetation associations … 3.3 open spaces with little or no vegetation … 4.1 wetlands inland wetlands … 4.2 maritime wetlands … 5.1 water bodies inland waters … 5.2 maritime waters … 36 iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. new natural plots shown, representing 90% of all new natural areas. in veszprém the artificial areas have remarkable increase with more than 15% of all changes within its administrative border; agricultural areas did not change (fig. 2, table 2). between 2000 and 2006 the changes are modest; however, the ratio of unchanged areas is the lowest during the examined period – the lowest in the settlement group with about 75%. remarkable, that during this period no new natural and agricultural area were detected, only the ratio of new artificial areas grew. only at broader surrounding of veszprém were new natural and agricultural areas identified – at fua fringe more agricultural, at the settlement group fringe more natural ones. the period of 2006-2012 can be described by intensive increase of artificial areas. not only in veszprém (41.7 ha) but at the settlement group fringe (35.9 ha) and fua fringe (52.2 ha) significant changes are seen. in addition to this only at fua fringe were new agricultural areas detected. there were no new agricultural and natural areas at inner fringe and core town. in the last 6 years, between 2012 and 2018, the area of new artificial surfaces has grown further – altogether 136 ha concentrated in the surrounding of veszprém, and the quantity of new natural surfaces also increased: in veszprém 97.5 ha, in settlement group fringe 33.3 ha and in fua fringe 55.3 ha was identified. according to our analyses focusing on new artificial areas the tendency of changes is different in the examined zones. the most intensive increase of artificial surfaces is identified in the settlement group fringe, in the direct neighbourhood of veszprém (table 3, fig. 3). the trend shows intensive boom of new artificial areas after 2000, between 2000 and 2018 with a growth of 111 ha in fua fringe, 185 ha in settlement group fringe and 135 ha in veszprém. the changes show different tendencies, the settlement group fringe shows increase in the last 6 years, however in veszprém a modest increase and in fua fringe decrease is experienced. in the last period the structure of the artificial areas also differs from each other: the highest ratio of new areas is urban green in fua fringe, urban fabric in settlement group fringe and industrial in veszprém after 2012. fig.2 land use changes focusing on new natural, agricultural and artificial areas at veszprém and its surrounding between 1990 and 2018 (data source: corine, google earth) iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. 37 it is also worth noting, that the new industrial areas are dominant (more than 50% of new artificial areas) in veszprém, except the period of 2006 -2012, when transport units represent the 57% (24 ha) of all new artificial areas. the ratio and the extent of new industrial areas are marginal at the settlement group fringe and fua fringe, this fact highlights the strong economic concentration in the examined area. the expansion of urban fabric is typical at fua fringe between 1990-2006, but after there is no new plot for this purpose until now. at settlement group fringe urban fabric expansion is experienced between 2000-2006 and 2012-2018, just the same as in veszprém. during the period of the economic crisis, between 2006-2012 there were no new urban fabric plots at all. it is also interesting, that urban green (new areas for urban green, sport and leisure facilities) is relevant at fua fringe areas. during the years of the economic crisis 90% of new plots (47 ha) fall within this category. these plots– for example golf clubs, tracks – are usually located further from the in-built area of the municipalities. however, the same tendency is visible at the settlement group fringe between 1990 and 2000 (77%, 28.6 ha). in veszprém the new urban green is negligible in all examined periods. table 2 land use changes in different agglomeration zones according to main categories expressed in ha and ratio of the whole area of the agglomeration zone (data source: corine, google earth) 1990-2000 2000-2006 2006-2012 2012-2018 core town new natural areas 21.85 ha / 0.172% 0.0 ha / 0.000% 0.0 ha / 0.000% 97.5 ha / 0.768% new agricultural areas 0 ha / 0.000% 0.0 ha / 0.000% 0.0 ha / 0.000% 0.0 ha / 0.000% new artificial surfaces 119.4 ha / 0.941% 46.4 ha / 0.366% 41.7 ha / 0.328% 47.3 ha / 0.373% unchanged 665.8 ha / 5.245% 178.3 ha / 1.405% 257.8 ha / 2.031% 144.9 ha / 1.142% changed areas together 807.0 ha / 6.358% 224.7 ha / 1.771% 299.5 ha / 2.360% 289.7 ha / 2.283% inner ring new natural areas 0.0 ha / 0.000% 18.8 ha / 0.045% 0.0 ha / 0.000% 33.3 ha / 0.081% new agricultural areas 29.6 ha / 0.072% 0.0 ha / 0.000% 0.0 ha / 0.000% 0.0 ha / 0.000% new artificial surfaces 37.0 ha / 0.090% 79.9 ha / 0.194% 35.9 ha / 0.087% 69.0 ha / 0.167% unchanged 2136.1 ha / 5.180% 269.5 ha / 0.653% 675.8 ha / 1.639% 463.0 ha / 1.123% changed areas together 2202.7 ha / 5.341% 368.1 ha / 0.893% 711.7 ha / 1.726% 565.3 ha / 1.371% outer ring new natural areas 167.2 ha / 0.216% 0.0 ha / 0.000% 0.0 ha / 0.000% 55.3 ha / 0.072% new agricultural areas 33.6 ha / 0.043% 4.2 ha / 0.005% 53.1 ha / 0.069% 20.1 ha / 0.026% new artificial surfaces 59.9 ha / 0.077% 39.3 ha / 0.051% 52.2 ha / 0.068% 19.7 ha / 0.025% unchanged 2247.1 ha / 2.904% 572.6 ha / 0.740% 1651.0 ha / 2.134% 1266.9 ha / 1.637% changed areas together 2507.9 ha / 3.241% 616.1 ha / 0.796% 1756.3 ha / 2.270% 1362.1 ha / 1.760% table 3 land use changes in different agglomeration zones according to categories of artificial surfaces expressed in ha and ratio of new artificial surface in table 2. (data source: corine, google earth) 1990-2000 2000-2006 2006-2012 2012-2018 core town new industrial, commercial units 107.8 ha / 90.3% 31.5 ha / 67.9% 6.7 ha / 16.0% 24.0 ha / 50.8% new urban green areas 0.0 ha / 0.0% 0.0 ha / 0.0% 0.0 ha / 0.0% 1.9 ha / 4.0% new transport units 0.0 ha / 0.0% 0.0 ha / 0.0% 23.7 ha / 56.9% 0.0 ha / 0.0% new mine sites 5.9 ha / 4.9% 0.0 ha / 0.0% 11.3 ha / 27.2% 6.0 ha / 12.6% new urban fabric 5.7 ha / 4.7% 14.9 ha / 32.1% 0.0 ha / 0.0% 15.4 ha / 32.5% inner ring new industrial, commercial units 8.2 ha / 22.2% 10.4 ha / 13.1% 6.0 ha / 16.8% 0.0 ha / 0.0% new urban green areas 28.6 ha / 77.2% 1.6 ha / 2.0% 0.0 ha / 0.0% 6.0 ha / 8.6% new transport units 0.0 ha / 0.0% 0.0 ha / 0.0% 16.2 ha / 45.1% 0.0 ha / 0.0% new mine sites 0.2 ha / 0.5% 5.1 ha / 6.4% 13.7 ha / 38.1% 32.9 ha / 47.7% new urban fabric 0.0 ha / 0.0% 62.7 ha / 78.5% 0.0 ha / 0.0% 30.2 ha / 43.7% outer ring new industrial, commercial units 0.0 ha / 0.0% 6.3 ha / 16.0% 5.3 ha / 10.1% 0.0 ha / 0.0% new urban green areas 16.0 ha / 26.7% 0.1 ha / 0.4% 46.9 ha / 89.9% 15.5 ha / 78.7% new transport units 0.0 ha / 0.0% 0.0 ha / 0.0% 0.0 ha / 0.0% 0.0 ha / 0.0% new mine sites 12.9 ha / 21.5% 14.7 ha / 37.5% 0.0 ha / 0.0% 4.2 ha / 21.3% new urban fabric 31.0 ha / 51.8% 18.1 ha / 46.1% 0.0 ha / 0.0% 0.0 ha / 0.0% 38 iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. the spatial pattern of the changes as the map shows (fig. 4, 5) new artificial areas are situated around the in-built areas of municipalities. exceptions are found, especially from the period of 2006-2012 and 2012-2018. it is also remarkable, that the density of the new artificial areas is higher on the edge of the in-built areas of veszprém, at the coast line of balaton and the main roads of nr. 8 (to körmend), e66 (to székesfehérvár and budapest) and 77 (to nagyvázsony). at the northern part of the study area, németbánya, zirc and dudar have new artificial areas from 1990, among which zirc seems to have continuous development. analysing the distribution of these areas (fig. 5), it can be stated, that new industrial and urban fabric areas are strongly connected to existing built in areas of municipalities, and former existing industrial sites from the socialism. at outer ring new industrial and commercial areas appeared only in municipalities, that has industrial tradition (balatonfűzfő, nagyvázsony). in addition to this, new mining and transport sites are so called ‘green field’ development – set on agricultural or natural areas. important fact, that urban green areas are also situated far from the core in built areas, and dense urban fabric, also transformed from non-artificial surfaces. policy responses for sustainable land use management there are several tools to control urban sprawl in hungary. the most important on country level is the renewed act on land use framework plan of hungary and priority areas (act nr. cxxxix. 2018), that tries to guide the settlements developing according to the compact settlement structure. this act aggregates the interest of different fields, like nature conservation, agriculture, forestry etc. in our comparison analysis, the act, adopted in 2003 was used, to be able to follow the effectiveness of regulation (act xxvi on land use framework plan of hungary from 2003). fig. 3 land use changes focusing on new artificial areas: industrial, commercial units, urban green areas, transport units, mine sites and urban fabric at veszprém and its surrounding between 1990 and 2018 (data source: corine, google earth) iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. 39 the municipalities have to follow the regulations of the national spatial plan. although the frame is given, the municipalities have a considerable freedom in management of the land use system in their administrative area by elaborating urban management plans (urban development plan, land use plan and building plan). the land use changes were also compared with the land use plan of veszprém from 2005. the natura 2000 network initiated by the european union’s habitats directive, 92/43/eec, and birds directive 2009/147/ec was defined on national level. in hungary some activities require authorisation from competent nature protection authority and require habitat management plans. certain activities (like hunting, fishing, tourism or mining) are possible if it is compatible with the protection. at our examined area (fig. 5) only some new mining and transport plot falls on the area under natura 2000 protection. the national ecological network zone (fig.6) – that contains inter alia all the natura 2000 areas – permits land use that are compatible with the preservation of natural values, however different regulations are applied for the core areas, buffer zones and ecologic corridors. after 2000 several land use changes fall on these areas, urban fabric, transport areas, mining units, even industrial and commercial sites. fig.4 categories of newly built artificial areas between 1990-2018 in core town, inner ring and outer ring, illustrated with all artificial surface based on urban atlas 2012 (data source: clc changes layers 1990-2018, urban atlas 2012) fig. 5 newly built artificial surfaces in different time periods, in core town, inner ring and outer ring and natura 2000 areas, illustrated with all artificial surface based on urban atlas 2012 (data source: clc changes layers 1990-2018, urban atlas 2012, termeszetvedelem.hu) 40 iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. the land use framework plan of hungary, 2003 appointed zones for forests and arable land of exceptional quality (fig.7). the high-quality forests zone prohibits construction, the high-quality arable zone allows exceptional building with permission of authority. after 2000 no new artificial areas appeared within these zones. however, at the examined area not a great extent of high quality arable can be found. a new tool of land use framework plan of hungary, 2003 was the opportunity for common planning (fig. 8) for agglomerations and settlement groups defined by the hungarian statistical office. in hungary there are not really good examples and practice for a such strong common planning activity among municipalities. maybe that is the cause, that no one had chosen this opportunity, nor veszprém. the national land use plan (fig. 9) marked the new main road (e66) without exact path and supplementary infrastructure. veszprém’s land use plan was adopted in 2005 in accordance with the national land use plan. that is why the presented study focused on the period between 2006 and 2018. during these years altogether 87 ha area was turned to artificial according to the authors’ evaluation. most of these changes (81%) followed the spatial structure of the land use plan. specific sites turned to mining and transport areas between 2006-2012 from semi natural areas do not fit into the foreseen spatial structure of the masterplan. it is also considerable, that these plots were formerly natura 2000 areas. another example is the new area of veszprém zoo, that was turned to urban green area from forest for recreational purposes. despite of the negative examples the new artificial areas are directly connected to the morphological urban area and urban sprawl is controlled, as it was foreseeable in the land use plan from 2005 (fig. 9). fig.6 national ecological network zone from national land use plan 2003 and new artificial surfaces in the study area fig.7 high quality forests and arable land from national land use plan 2003 and new artificial surfaces in the study area iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. 41 discussion and conclusion in the presented research the urban sprawl around veszprém is detected with the help of land use changes from corine database, visualised with urban atlas map from 2012. the artificial surface is larger in veszprém, than at inner fringe, the lowest in outer fringe, mostly with the loss of agricultural and natural surfaces. the most intensive period is the restructuring after socialism, between 1990 and 2000. important changes are detected during the economic crises, between 2006 and 2012, when the land use moved to the direction of artificial surfaces, especially at the core town and inner fringe. we can state that the crises consumed the agricultural areas – 95 ha agricultural and 35 ha natural area was turned to artificial. in the last six years the growth of artificial surfaces continued, however new natural areas appeared in veszprém and in the outer fringe. agricultural areas are the losers of land use changes, and this finding fits to the european and hungarian trends (espon 1.1.2. 2006; ricz et al., 2009). the period of 1990-2000 is the age of reorganisation and industrial renewal, that meant a surface intensive growth in and around veszprém. in european level the changes are not outstanding (espon eu-lupa, 2014; grigorescu and kucsicsa, 2017) and in budapest similar fig.8 zone for region for common planning from national land use plan 2003 in the study area fig. 9 artificial land use changes are not fit into the veszprém land use plan from 2005 42 iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. trend is detected (szilassi, 2017). because of the rural characteristic of the outer fringe, the new natural areas are dominant (more than 78% of new artificial areas after 2006), however artificial and agricultural areas can be also detected. in the inner fringe the characteristic moved to agricultural and artificial surfaces, in veszprém more to the direction of artificial surfaces. after 2000 the inner fringe gained several new artificial plots, and we found the patterns of a municipality driven housing in the core town. after 2006, the new artificial areas showed different quality. no new housing plots appeared, even in the core town, however new transport and mining units were characteristic, also some urban green and recreational areas at fringe. these changes can be explained by the effects of economic crises, and the dominance of eu funds, from these were the transport investments financed presumably. in the last six year, in parallel with the continuous and balanced growth of core town, in the inner fringe new artificial surfaces became remarkable again (70 ha), however, the urban development of outer fringe seems to slow down. if the distribution of new artificial spaces is examined, different tendencies are experienced at outer, inner fringe and core town. the industrial development – according to our data – is concentrated in the core town, that is the pole of the examined region. the most intensive period of this concentration – due to the inherited socialist sites and central driven development – is between 1990 and 2000 in veszprém. the inner fringe can be described as the place for living, also has some industrial development, but not dominant. the outer fringe started to be favourable for living purposes, however lagging behind the core and inner areas, only few plots were transformed to industrial. at the time of industrial reorganisation of the capitalism and during the last 6 years no new industrial sites appeared. the recreational function strengthened in these areas thanks to several new artificial green areas for recreation. an interesting tendency is the change of new sites for urban green, sport and leisure facilities. these are not situated in the in-built areas – the scale of corine database even not suitable to detect such minor changes – but are found on natural areas, further from morphological urban area. in veszprém only between 2012 and 2018 is dedicated a plot to this purpose, for the above-mentioned zoo. in the inner fringe significant period is between 1990 and 2000, after 2000 only minor plots were turned to urban green. at fua fringe the tendency is almost opposite; between 2006 and 2012 a boom is seen. this artificial land use category is dominant also after 2012, but the extent of changed areas dropped. some of these areas were turned to golf club, camping sites, or track for horse racing. transport development dominated during the crises, mostly financed by eu. in addition, these developments also concentrate more to the core town, than inner fringe. the new plots for mining are scattered during the periods and in the fringe of agglomeration. it is not surprising, that most of the new sites for mining appeared between 2012 and 2018, because for this region the typical natural resource is raw material used in constructions. the development of urban fringe also mirrors the tendencies of economic changes. during the period of crisis, no new plots were opened for urban fabric. during the period of 1990 and 2000 the outer ring seems to be preferred, 31 ha new urban fabric appeared. this has almost halved for the next period, and no new urban fabric was detected during the crises. in the last 6 years it did not became popular, but some new areas were dedicated for living. at inner ring the suburbanisation and thanks to this new plot came up during 2000-2006 and 2012-2018. in veszprém – not to count the years of crises, the quantity of new areas for urban fabric was continuously growing. the intensive growth between 2000 and 2006 of urban fabric was the result of municipality policy. the wellknown national policies for family support after 2012– for example csok support (financial aid for buying flat/house for families) – do not have any effect on the outer fringe, but in inner fringe and core town is visible through land use changes. not surprising the spatial pattern of developments. the new industrial and residential areas are strongly connected to the morphological urban area and main roads. furthermore, the location of new industrial sites follows the socialist heritage and are mostly opened in the neighbourhood of former industrial units. this can be explained with the importance of transport and logistic facilities nearby, as an economic incentive at other hungarian towns, miskolc and győr as well (lux, 2014). the transport units, mining sites and urban green areas are scattered in the rural areas. according to the result, the most vulnerable areas of urban sprawl are at catchment area of main roads outside the town in urban fringe. effectiveness of tools of land use control were also analysed, however several soft solutions also exist outside the well-known land use plans and nature protection areas. in the future it would be worth to make a deep analysis of the different land use plans and their modifications. in present study emphasis was put on the most important zones from 2003 and the core town from 2005. according to this the high-quality forests zone had the strictest regulations that was successful, because no new artificial surface appeared. the high-quality arable zone was not so strict, and not dominant at the examined area, however, was successful because these valuable areas did not turn to artificial. almost the same regulation was at the case of ecological network zone – except the buffer zone where building-in is allowed. this might be the reason for several plots turned to artificial on these areas. typically mining sites and transport units appeared at the natura 2000 protection areas. the zone for region for common planning did not reach its aim at all. at the case of veszprém the land use plan was able to hold new development close to the morphological urban area, however two unplanned construction sites were opened: the e66 road construction and a new mining site near to the main road. however, special regulation for peri-urban areas do not exist, the framework of land use control can be effective, not to mention some special cases. in this term the regulatory possibility in hungary are better than in estonia, where planning control is iváncsics and filepné kovács 2019 / journal of environmental geography 12 (3–4), 33–43. 43 missing (roose et al. 2013) or in poland where only 30% of municipalities have land use plans (filepné et al. 2018). beside the land use plans and regulations economic changes have also great effect on land use changes. for the future it would also be necessary to prove our assumptions with statistical data, exploring correlation between the land use changes and economic development or social trends. the research was focused on the fua of veszprém, but a comparison analyses could have new results. based on veszprém’s unique development and geographical situation assumptions could not be made to the whole country – the neighbourhood of balaton agglomeration with one of the strongest regulation for nature protection and land use or the relatively large military area at the northern part also affect the land use trends. references act cxxxix on 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(ed.) 2005. agglomerációk és szuburbanizálódás magyarországon, szombathely. 35–51 urban atlas database 2012. https://land.copernicus.eu/local/urban-atlas woltjer, j. 2014. a global review on peri urban development and planning, jurnal perencanaan wilayah dan kota 25(1), 1–16 zivanovic-miljkovic j.,crncevic, t. maric, i. 2012. land use planning for sustainable development of peri-urban zones. spatium 15–22. doi: 10.2298/spat1228015z http://net.jogtar.hu/jr/gen/hjegy_doc.cgi?docid=a0300026.tv introduction study area methods results the ratio of different land use categories the spatial pattern of the changes policy responses for sustainable land use management discussion and conclusion references journal of environmental geography journal of environmental geography 10 (1–2), 1–10. doi: 10.1515/jengeo-2017-0001 issn: 2060-467x hydrocarbon pollution and potential ecological risk of heavy metals in the sediments of the oturuba creek, niger delta, nigeria clinton ifeanyichukwu ezekwe1*, israel clinton utong2 1department of geography and environmental management, university of port harcourt, pmb 5323 choba, e-w rd, 500001 port harcourt, nigeria. 2environmental monitoring and compliance department, the shell petroleum development company, pob 263, rumuobiakani, 500001 port harcourt, nigeria *corresponding author, e-mail: clinton.ezekwe@uniport.ng.edu research article, received 10 october 2016, accepted 28 february 2017 abstract this study aimed at examining the impact of oil pollution from artisanal oil refineries on the oturuba river ecosystem using active river bottom sediment. specific objectives included to determine the level of hydrocarbons and trace metals (pb, cd, zn, cu, ni, v and mg) in the sediments and to relate this with general ecosystem health. the study found elevated concentrations of both hy drocarbons and heavy metals in the range above most sediment quality guidelines exceeding the respective threshold effects l evel and probable effects. level guideline values and occurring at levels where impairment to biological communities is certain an d where toxicity levels can lead to negative impacts on benthic animals or infaunal communities. heavy metal geochemical accum ulation index and potential ecological risk analysis also returned anomalously high concentrations in the range of very highly polluted sediment environments with very high ecological risk indices, thereby ranking the oturuba creek as one of the most pollu ted coastal river systems in the world. keywords: sediment pollution; trace metals; artisanal refining; estuaries; andoni river introduction the survival of coastal rivers and estuaries which are among the most sensitive and biologically productive habitats on earth is currently being threatened by human activities including oil production. coastal rivers are dynamic ecosystems with spatial and temporal fluctuations in reach and constituents. concentrations of organic and inorganic constituents in coastal river systems, especially metals and hydrocarbons are mediated by biogeochemical forcings such as sediment composition and texture, sediment-water redox reactions, ph, temperature, salinity, nutrients and oxygen availability, microbial populations, competition, transportation dynamics and anthropogenic perturbations (förstner and salomons, 1981; whitehead, 2013). these anthropogenic disturbances and naturally induced biogeochemical stressors may impose suboptimal conditions leading to physiological adaptations or forced migration by resident species. for instance, oil pollution in coastal river systems through oil-induced oxygen-deficiency, toxicity, asphyxiation, coating or smothering, which affects gas exchange, thermo-reactions and osmoregulation, can threaten the life-support processes in a river ecosystem by imposing hypoxic conditions thereby affecting community resilience and population dynamics (luoma et al., 1997; mendelssohn et al., 2012; whitehead, 2013). sediments are sinks for contaminants in river ecosystems and their physico-chemical properties and response to the chemical dynamics of the hydrological system may enhance subsequent contamination to the ecosystem components to which they are linked. significant contamination of sediments may lead to species and biodiversity losses (markovic, 2003; luoma, 1990) and deleterious food chain reactions from benthic communities to upper trophic levels (burton, 2002) either through direct adverse impacts on bottom fauna or by becoming long-term sources of toxic substances to the environment. they can also impact wildlife and humans through the consumption of food or water or by direct bodily contact. of critical importance, is that these impacts may be present even though the overlying water meets water quality criteria (usepa, 1992) thereby underscoring the importance of sediment quality analysis in monitoring ecosystem integrity. river bottom or deposited channel materials represent the closest approximation of sediment provenance, movement and deposition, however directly linking sediment chemistry data to observed adverse biological effects on organisms is problematic (usepa, 2005), hence, a few screening guidelines, indices or benchmarks (below which toxic effects are not expected to occur and above which toxic effects are usually expected) relate chemical concentrations in sediments to their “potential for biological effects” (bay et al., 2012). 2 ezekwe and utong (2017) buchman (2008) presented sediment screening levels based on threshold effects level (tel), effects range-low (erl), and probable effects level (pel) for evaluating sediment quality. tels define chemical sediment concentration benchmarks where toxic effects are scarcely observed in key indicator organisms while pels on the other hand define concentrations which when exceeded can cause observable detrimental effects on organisms. erl thresholds are statistical derivations of the10th percentile concentration of chemicals in samples identified as toxic occurring between the tel levels and the pel benchmark. also heavy metals in sediments have been used successfully in calculating pre-industrial and anthropogenic pollution sources and ecological risks in sediments (håkanson, 1980, 1988; forstner, 1989; singh et al., 2003; li et al., 2012) and more recently in the analysis of groundwater contamination in industrial areas (bhutiani, 2017). these benchmarks which have been previously tested and accepted have been applied in this study to measure the impact of artisanal oil refining activities on the ecosystem health of the oturuba creek where illegal crude oil refining activities has been ongoing since 2010 and where ambient ecosystem destruction and reduction in fish catch has been observed. this study therefore attempts to show the latent and manifest ecological impacts of hydrocarbon and heavy metal concentrations in sediments of the oturuba creek, hence similar ecological systems. it also aims to show the relationships and spatio-temporal spread of heavy metals and hydrocarbons in the oturuba creek. study area oil was first discovered in commercial quantities in 1956 in nigeria in the freshwater swamps of the niger delta, around oloibiri, currently in the bayelsa state of nigeria. since then the niger delta environment and its eco-systems have been adversely impacted and altered by oil and gas exploration and exploitation. this has triggered a conflict of interest and sometimes armed conflicts between production/facilities host communities on the one hand and the federal government and oil companies on the other. this has led to wanton pipeline vandalism, oil theft, illegal bunkering and illegal refining (using makeshift refineries) of probably stolen crude oil, and consequent oil spills into, and damage to the environment. when oil is spilled, it is washed into water bodies (as in the study area) via surface run off and may persist (bio-accumulate and bio-transform) in the media it attaches to for a very long period of time. about 50% of spilled oil evaporates, others migrate and stray away via the action of wind and tidal waves, others emulsify, while a percentage of it, unnoticeably, sinks to the bottom of the river bed and permeates into bottom sediments (usepa, 1999). the oturuba creek is a tributary of the andoni river -a major river which drains the eastern part of the niger delta of nigeria. the creek (fig. 1) has an approximate length of about 3.66km and width of about 100m, and average depth of about 3.7 metres. the river stretch starts from the egwede area and drains into the andoni river in the inter-tidal mud flat mangrove ecosystem terrain characteristic of the eastern niger delta coastline. it is a lowlying terrain (< 5 m asl) and consists of about 3-5 m of soft mud with high organic matter content. the oturuba fig. 1 location of the study area and the sample sites (ss) hydrocarbon pollution and potential ecological risk of heavy metals in the sediments … 3 creek is a permanently saline sheltered river system tied to the tropical deltaic tide influenced andoni river system with its characteristic silty muds, acidic sediments (ph: 4.09 –5.04), high water temperatures (26.2–32.4°c), deep waters (17 fathoms) and wide water salinity ranges (8– 21ppt) (ssentongo, ukpe and ajayi, 1986; ansa et al., 2007; ansa and francis, 2007; ezekwe and edoghotu, 2015). the study area also falls within the transitional zone of the aw and af climate types of the koppen’s climatic classification scheme. it is thus characterized by long hours of day light, high temperatures of about 27oc and high rainfall (≥ 1,800mm). materials and methods sample sites sediment samples were collected from six sample sites after an initial reconnaissance of the study area. the geographical location of each sampling point (fig. 1) was recorded using handheld gps equipment (garmin 76) and described in table 1. table 1 sampling sites sampling site latitude longitude site description 1. sse 4o 28ʹ 40.675ʺn 7o 20ʹ 53.685ʺe first point upstream near the mouth of the oturuba creek (about 1 km from poi) close to the andoni river. 2. ssd 4o 28ʹ 38.963ʺn 7o 21ʹ 13.654ʺe about 500 m upstream from point of impact (poi). 3. ssa 4o 28ʹ 50.945ʺn 7o 21ʹ 23.353ʺe point of impact (poi) where raw waste from the crude oil refining process, refined products and sludge are discharged into the creek 4. ssb 4o 28ʹ 42.95ʺ7n 7o 21ʹ 37.046ʺe about 500 m downstream 5. ssc 4o 28ʹ 50.374ʺn 7o 21ʹ 53.592ʺe about 1 km downstream 6. ssf 4o 29ʹ 05.78ʺn 7o 23ʹ 15.43ʺe about 3.7 km downstream (control; un-impacted area. visual observation of site1 conditions showed that the site had relatively buoyant biomass; which can be attributed to its location, almost at the point where the oturuba creek joined the andoni river and therefore receives fresh and relatively uncontaminated water from the larger andoni river system. oil sheen was only observed on the surface of the water during ebb tides. site 2 had oil sheens on the surface of the river with mud flats on both sides of the river showing signs of heavy oil-staining. it was also characterised by scanty and unhealthy looking fauna and flora especially mangroves plants and crabs. site 3 or the point of impact (poi) was characterized by greasy and muddy surfaces with darkened soils and scorched vegetation. the site was bereft of visible biological activity as no marine organisms were spotted in the vicinity during the fieldwork. oil sheen and slicks were seen floating freely on the surface of the creek; while site 4 had oil sheen on the surface of the water, especially during low tide. mangrove plants were sparse with a few marine fauna such as juvenile periwinkle, crabs, mudskipper, etc. in the mangrove mud. the mud had oil stains as in the point of impact but no direct inlet of spilled oil into the water body was observed. this immediate downstream sampling site from the poi was the most impacted section of the creek after site 3. at site 5, mangrove plant species were densely populated and there where sightings of crabs, mudskipper, periwinkles and birds. the mud and surface water showed very little sign of pollution. at site 6, which served as the control site for this study, the mangrove vegetation was dense and green with an abundance of bio-activity (crabs, periwinkles, mudskippers, birds, reptiles and other aquatic invertebrates). the mangrove mud flats and water did not show any visible sign of contamination. sample collection and analysis river bottom sediments were collected from the 6 designated locations in the oturuba creek following methods outlined by marcus et al. (2013). sediment samples were collected by the grab method in triplicates at low tide in june 2013 (rainy season) and november 2013 (dry season) (apha, 1998). samples for hydrocarbon analysis were stored in sterilized bottles, while the samples for the analysis of trace metals were stored in polythene bags previously washed in diluted hcl while those for organic matter analysis were collected in aluminium foils. samples were stored in polyethelyne sealed and stored in ice packed plastic coolers (below 4⁰c) thereafter, transported to the laboratory and analyzed within 2 days. the sediment samples were allowed to thaw and were air-dried at ambient temperature ground and sieved through a 0.5 mm mesh. later, 2 g of each sample was digested using 25 ml 1:3:1 mixture of hcio4, hno3 and h2so4 acids in a water bath. 10 ml deionized water was added to the digest and decanted into 50 ml standard flask and made up to mark with deionized water after rinsing. the buck scientific atomic absorption spectrophotometer model 200a and air-acetylene flame were used for trace metal analyses with quality assurance checked with standard sediment sample pacs-2 using an intra-run quality assurance standard (1 mg/l, multi-element standard solution, fisher scientific) after every 10 samples (cantillo and calder, 1990). the walkley-black wet chemistry “reference” procedure for the determination of total organic carbon as described in schumacher (2002) and applied by marcus 4 ezekwe and utong (2017) and ekpete (2014) was used in analysing total organic carbon (toc) in this study. 1 g of dried, sieved sediment was put into 250 ml conical flask and digested with 10 ml 0.5 m k2cr2o7 and 20 ml concentrated h2so4, swirled and allowed to cool. to overcome the concern for incomplete digestion of organic matter, the sample and extraction solutions were gently boiled at 150 ºc for 30 minutes and allowed to cool (walkley and black, 1934; tiessen and moir, 1993). when cool (after 20–30 minutes), 100 ml deionized water was added for dilution and 3 or 4 drops of ‘ferroin’ indicator was added and titrated with 0.4 n feso4 solution (nsw eh, 2015). results of toc were reported as percentage and later converted to dry weight (table 1) by multiplying total organic matter content (%) by sediment bulk density (1.61 gcm-3) and depth (20 cm) of sampling (pluske et al., 2016). samples for hydrocarbon analysis was weighed to obtain wet weight, and then sun-dried and then grounded to powdery form and sieved with a 1.0mm sieve. the sieved samples were stored in well-labelled smaller plastic containers with cover, from where samples were withdrawn for analysis. 5g each of dry powdery samples were weighed out and placed in 250ml beakers. to this was added 30ml of xylene; the beaker was then swirled/shaken for about 5 minutes and allowed to settle, the mixture was later filtered into a clean 100ml standard flask through a whatmann filter paper that contains about 2g of anhydrus sodium sulphate on a cotton wool. this was done three times and was later made up to the 100ml mark with xylene. the absorbance of the filtrate was measured at 340nm using hach dr 2800 spectrophotometer. the corresponding concentrations of total hydrocarbon (thc) content were then obtained from the calibration curve and calculated on dry weight basis. same procedure was applied to the analysis for total petroleum hydrocarbon (tph), although, after the extraction, the filtrate was treated with silica gel to remove non-petroleum hydrocarbons and re-filtered. the readings were obtained in the same manner with that of thc and the final value calculated as usual (howard et al., 2009). calibration of the spectrophotometer (hach dr 2800) was carried out before each analysis using diluents of a stock solution of 1ml of crude oil in 100ml of xylene at 340nm in line with astm (2003) and howard et al. (2009). environmental impact and ecological risk assessment methods environmental impacts of oil contamination and potential ecological risks were calculated by analysing the relationships, differences and similarities between contaminant concentrations in sample sites. contaminant concentrations in sediments were further compared with sediment quality guidelines including; the national ocean and atmospheric administration of the usa (noaa) and the dutch government intervention values (verbruggen, 2004) for the protection of ecosystems using the apparent effects threshold (aet), the effects range low (erl), effects range medium (erm), the threshold effects and probable effects level (tel/pel) (imo, 2000) and maximum permissible concentrations (mpcs). potential ecological risk index (peri), a diagnostic tool suggested by håkanson (1980, 1988) for the analysis of contamination in lakes and coastal systems was used to calculate an ecological risk index for the oturuba river ecosystem. peri is formed by three basic modules: degree of contamination (cd); toxic-response factor (tr 1); and potential ecological risk factor (eri). the first module of peri corresponds to the estimate of the degree of contamination (cd). the cd is expressed by the sum of the contamination factor of each metal (cf i) as: 𝐶𝐷 = ∑ 𝐶𝑓 𝑖 where, cf i, is the mean metal concentration (ci), divided by the pre-industrial concentration of the substance (c0 i): 𝐶𝑓 𝑖=𝐶𝑖/ 𝐶0 𝑖 according to håkanson (1980, 1988), the potential ecological risk index (peri) is defined by: 𝑅𝐼 = ∑ 𝐸𝑟𝑖 𝐸𝑟𝑖 = 𝑇𝑟𝑖 ∗ 𝐶𝑓 𝑖 where; ri is calculated as the sum of all risk factors for heavy metals in sediments; eri is the monomial potential ecological risk factor; tri is the dimensionless derived toxic-response factor for a given substance (e.g., cu = 5, pb = 5, ni = 5, zn = 1, cd = 30), which mainly reflects the heavy metal toxicity level and the degree of environment sensitivity to pollution from a particular heavy metal (jiao et al., 2015). cif, c i 0, and c i n are the contamination factor, the concentration of metals in the sediment and the background reference level, respectively. international background values for metals in sediments (shale) include 0.22 mg/kg for cd, 39 mg/kg for cu, 68 mg/kg for ni, 120 mg/kg for zn, 0.85 mg/kg for mn (rodrigues et al., 2006) and 60 mg/kg for pb (li et al., 2012). håkanson (1980) also proposed the following values to be used in the interpretation of ecological risks in sediments:  ri <150, low ecological risk for the sediment;  150≤ ri <300, moderate ecological risk for the sediment;  300≤ ri <600, considerable ecological risk for the sediment;  ri ≥600, very high ecological risk for the sediment. in order to assess the intensity of metal contamination in the sediments of the oturuba creek, the geochemical accumulation index was calculated using the equation proposed by singh et al. (2003) to quantify metal accumulation in the sediments, and represent their contamination degree. this index is expressed as follows: 𝐼𝑔𝑒𝑜 = log2 𝐶𝑛 / 1.5 𝐵𝑛 where igeo is the geochemical accumulation index; cn is the total concentration of metal n in the silt/clay fraction; hydrocarbon pollution and potential ecological risk of heavy metals in the sediments … 5 bn is the geochemical background value of element n and 1.5 is a correction factor due to lithogenic effects. the igeo classification entails seven grades (0 to 6) of pollution, ranging from no pollution (0) to very high pollution (forstner, 1989). results and discussion heavy metals, organic matter and hydrocarbons in the sediments the results of the analysis of sampled sediments are presented in figure 2. organic matter concentration ranged between 201 (mg/kg) and 2782.1(mg/kg) with both lowest and highest concentrations occurring in the wet season. highest concentrations occurred 500m downstream (site 4) from the point of impact in both seasons. concentrations of copper in the sediment ranged between 4.78 – 83.5 mg/kg with highest and lowest concentrations occurring in site 4 and 6 in the dry season respectively. concentrations also followed the same pattern in the wet season (6.24 mg/kg – 50.02 mg/kg) although with slightly lower concentrations in site 4. concentrations of copper (4.78 – 83.5 mg/kg) in sediments were above the dutch maximum permissible concentrations (73 mg/kg) in site 4 in the dry season. copper concentrations were also above the tel (18.7 mg/kg) in 7 out of 12 cases and above the erl (34 mg/kg) in three cases while nickel exceeded tel limits (15.9 mg/kg) in 7 cases out of 12 in all seasons. concentrations of zinc ranged between 199.53 and 1007.8 mg/kg, lowest and highest concentrations occurred at site 1 and 6 respectively. the concentrations of zinc were higher in the dry season for all sites apart from site 6 and also above tel, erl and pel guidelines in all seasons. while lead concentrations (123.3 – 327.5 mg/kg) were above tel, pel and erl in all cases except for pel in the dry season in site 6 cadmium concentrations (38.1 – 259 mg/kg) were above all the standards in all seasons. for vanadium (1.21 – 5.24 mg/kg) and manganese (42.71 – 959.4 mg/kg) the only available guideline is the aet (57 and 260 mg/kg respectively). while all the sampling sites were below maximum specified limits for vanadium, manganese exceeded standards in sites 3, 4 and 5 in the dry season and all sampling sites apart from site 6 in the wet season. total petroleum hydrocarbons (tph) in sediments ranged from 3997.9 (mg/kg) dry weight at the poi to 1546 (mg/kg) at site 6 in the dry season. concentrations in the wet season followed a similar trend with ranges between 5118.5 mg/kg at site 3 and 1727.5 mg/kg in site 6. total hydrocarbon (thc) concentrations ranged between 5133.6 mg/kg in site 3 and 2151.2 mg/kg in site 6 in the dry season. there was however a slight difference in trend as the poi had a total concentration of 6118.5 (mg/kg) with lowest concentrations (2272.5 mg/kg) downstream in site 5. potential ecological impacts of heavy metals and hydrocarbons in the sediments species that are intolerant to metal contamination can be adversely affected in a number of ways from heavy metal pollution of marine sediments. impacts on reproduction and growth can impair the survival of individuals, and affect populations and communities. for instance, copper can be acutely toxic to microalgae at levels between 190mg/kg and 300 mg/kg (markovic, 2003). in this study, copper occurred between maximum contaminant limits and the low level effects range where biological activities can be impaired. also, recruitment can also be affected by metal contamination in clams (macoma bathilica) (langston, 1990; markovic, 2003). concentrations of zinc in this study occurred far above these toxic levels. negative impacts related to metal contamination do not necessarily result from direct toxicity but contaminant-related changes to phytoplankton communities may have serious consequences for higher trophic levels. a change in the phytoplankton community structure can lead to a reduction in preferred prey species, fig. 2 hydrocarbons, heavy metals and toc in the oturuba creek 0 1000 2000 3000 4000 5000 6000 7000 site 1 site 2 site 3 site 4 site 5 site 6 site 1 site 2 site 3 site 4 site 5 site 6dry season wet season cu(mg/kg.dwt) zn(mg/kg.dwt) mn(mg/kg.dwt) ni(mg/kg.dwt) v(mg/kg.dwt) cd(mg/kg.dwt) pb(mg/kg.dwt) toc (mg/kg.dwt) thc(mg/kg.dwt)/10 tph(mg/kg.dwt)/10 6 ezekwe and utong (2017) and ultimately the loss of higher trophic species in those communities. it is possible that the indirect effects triggered by the loss of sensitive species have a much more significant impact on marine communities than indicated by toxicity tests with an individual species (langston, 1990; markovic, 2003). all the trace elements in the bottom-sediment samples from this study also exceeded the respective tel and pel. according to usepa (1998), these values are in the range where toxic effects can occur to benthic organisms. these results suggest that heavy metal and hydrocarbon levels in the study area are at concentrations high enough to impair biological communities and are likely to cause toxicity levels that will lead to negative impacts on infaunal communities (table 2) including leptocheirus amphipods bivalves, neanthes worms, echinoderm and oyster larvae (adec, 2011). according to capuzzo (1985), retention of hydrocarbons in lipophilic cellular compartments may result in disruptions in membrane functions or alterations in energetic processes and impairment of an organism's adaptive capacity within its natural habitat. capacity for metabolism of lipophilic compounds may influence the disposition or removal of aromatic hydrocarbons by marine organisms. relationships, spatial and temporal variations of contaminants in the sediments organic matter in the study area tended to have a negative relationship with both total hydrocarbon and heavy metal concentrations without showing much variation in both seasons. this is at variance with the findings of jamil et al. (2014) and the reason for this difference may be a result of pη, salinity and grain size differences (du laing, 2009) which were not measured in this study. heavy metal concentrations increased progressively in both upstream and downstream directions in the dry seasons but tilted downstream in the wet season. thc concentration characteristics in the sampled sites also revealed profound between site variations. this could be indicative of the irregular pattern in waste discharges and spills and the power of tidal influence in redistributing contaminants in the creek’s ecosystem. a correlation matrix can indicate associations and relationships among metals and their sedimentary environments (table 2-4). high correlation coefficients between different metals in a matrix could mean that they have common sources, mutual dependence and identical behaviour during transportation and probably deposition. the absence of strong correlations among metals on the other hand may be indicative that the concentrations of these metals are not controlled by a single factor, but may be a pointer to a combination of geochemical support phases and the effects of the mixed association and interactions among the metals (veerasingam et al., 2012). table 2 proximity matrix of sampling sites for heavy metals correlation between vectors of values in the dry season ssa ssb ssc ssd sse ssf ssa 1 ssb .916 1 ssc .934 .985 1 ssd .863 .981 .985 1 sse .973 .847 .864 .774 1 ssf .739 .493 .475 .343 .828 1 correlation between vectors of values in wet season ssa ssb ssc ssd sse ssf ssa 1 ssb .923 1 ssc .938 .984 1 ssd .857 .967 .979 1 sse .974 .858 .873 .776 1 ssf .754 .526 .504 .362 .837 1 distances and similarities between sites were calculated using the pearson correlation statistics. results (table 2) for heavy metals revealed a high level of similarity among sites, although site ssf (background) was least similar to ssb, ssc and ssd in both seasons. the reason for dissimilarities is obvious; however, the similarity between sites ssf (background) and site ssa (poi) is not readily explainable. it may be posited that the tidal nature of the environment may be redistributing contaminants within the marine environment. results for toc, thc and tph (fig. 3 and table 3) also show a high level of similarity among sites. table 2 marine sediment quality guidelines (modified from noaa, 2008 and bay et al., 2012) mg/kg intervention dutch guidelines consensus sediment guidelines intervention values mpc tel erl pel erm aet pahs 40 1.684 4.022 16.77 44.8 mineral oil 1100 5000 cu 190 73 18.7 34 108 270 390 microtop larvae zn 720 620 124 150 271 410 410 infaunal community impacts mn 260 neanthes ni 210 44 15.9 20.9 42.8 51.6 110 echinoderm larva; bioassay larvae v 57 neanthes cd 12 0.68 0.68 1.2 4.21 9.6 3.0 neanthes pb 530 530 30.2 46.7 112 218 400 bivalve hydrocarbon pollution and potential ecological risk of heavy metals in the sediments … 7 table 3 proximity matrix of sampling sites for tph, thc and toc correlation between vectors of values in the dry season ssa ssb ssc ssd sse ssf ssa 1 ssb .988 1 ssc 1.000 .986 1 ssd 1.000 .992 .999 1 sse 1.000 .986 1.000 .999 1 ssf .998 .996 .997 .999 .997 1 correlation between vectors of values in wet season ssa ssb ssc ssd sse ssf ssa 1 ssb .987 1 ssc .999 .979 1 ssd .996 .997 .992 1 sse .915 .968 .897 .946 1 ssf . 996 .997 .990 1.000 .946 1 since the above analysis did not show very distinct relationships, the data was subjected to further multivariate statistical analysis using the pearson’s correlation to test for relationship between contaminants. results (table 4) of this analysis (strong – medium correlations verged in red) however revealed very weak relationships among the contaminants; however, only cupper and manganese; vanadium and thc; tph and toc had any form of significant strong relationship. subjecting the data to further query by principal component analysis (pca) using the varimax analysis with kaiser normalization rotation method (table 5); three components were realized accounting for 80.56% of observed variation in the dataset. principal component one (29.528%) has a strong relationship between tph and toc with a moderate association with zinc, cadmium and manganese. this factor is most likely an indication of pollution from uncooked crude oil spilled during transportation and precooking (refining) operations in the study area. the indicated petroliferous heavy metals have been identified (marcus and ekpete, 2014) as key components of crude oil from th is part of the niger delta. factor two which accounts for 26.71% of variance indicates a strong affinity between vanadium and thc. vanadium is a major constituent of nearly all coal and petroleum crude oils. the most prominent anthropogenic source of vanadium in the environment is the combustion of fossil fuels, particularly residual fuel oils, which also constitute the single largest overall release of vanadium to the atmosphere. while the levels of vanadium in residual fuel oil usually vary by source, concentrations of 1–1,400 ppm have been reported (atsdr, 2012). the third factor loaded 24.322% and has affinity for copper, lead and nickel. while urban sewage contains substantial amounts of copper, nickel is ubiquitous in the environment while lead is the most abundant heavy metals occurring in nature. this may therefore indicate mobilisation from natural sources and long distance pollution drifted from upstream sources in the port harcourteleme-onne industrial axis located northwest of the study area. table 5 rotated component matrix of variables component 1 2 3 cu .042 -.082 .887 zn .645 -.461 .095 mn .506 .137 .656 ni -.311 .060 .908 v .240 .938 .100 cd .613 -.391 -.127 pb .185 .612 .587 thc (x 0.001) -.013 .957 -.040 tph (x 0.001) .921 .197 .085 toc (%) .931 .262 -.042 extraction method: principal component analysis. rotation method: varimax with kaiser normalization table 4 pearson's correlation matrix of contaminants cu zn mn ni v cd pb thc (x 0.001) tph (x 0.001) toc (%) cu 1 zn -.014 1 mn .763** .219 1 ni .509* .407 .398 1 v -.014 -.184 .070 .268 1 cd .074 .229 -.233 .117 -.279 1 pb .458 .592* .450 .262 -.390 .168 1 thc (x 0.001) -.174 .395 .029 .063 .923** -.372 .498* 1 tph (x 0.001) .130 .459 -.191 .424 .415 .443 .167 .172 1 toc (%) .038 .386 -.278 .448 .436 .531* -.086 .190 .913** 1 ** correlation is significant at the 0.01 level (1-tailed) * correlation is significant at the 0.05 level (1-tailed) 8 ezekwe and utong (2017) potential ecological risk of heavy metals in the sediments calculated contamination factors for the various metals are cu: 0.652, zn: 205.73, mn: 560.34, ni: 0.321, cd: 472.5 and pb: 3.28, while international toxicity factors for cd: 30, ni, cu, pb and zn include 30, 5, 5, 5 and 1 respectively (li et al., 2012) while toxicity values for mn and v are not available. therefore, the degree of contamination (cd) for the oturuba creek system for the analyzed metals is 1,242.82. calculated eri for metals include 3.26, 205.73, 1.605,14,175 and 16.4 for cu, zn, ni, cd and pb respectively; giving a total value of 14,401.995, with cd contributing more than 98% of ecological risks followed by zn with 14.43%. going by the recommendations of håkanson (1980), the calculated eri for the study area is over 700% beyond the baseline for very high ecological risk metal concentrations. li et al. (2012) in a study of heavy metal contamination in sediments from a coastal industrial basin in northeast china concluded that the area “is one of the most polluted of the world’s impacted coastal systems”. however, evidence from this study shows worse but similar sediment quality situation. therefore, the oturuba creek can be declared to be one of the most polluted coastal rivers in the world. index of geoaccumulation (igeo) in order to assess the intensity of metal contamination in the sediments of the oturuba creek, the geochemical accumulation index was calculated as proposed by singh et al. (2003) to quantify metal accumulation in the sediments, and represent their contamination degree. the igeo classification entails seven grades (0 to 6) of pollution, ranging from no pollution (0) to very high pollution (forstner, 1989). table 6 igeo classes, range and sediment quality (singh et al., 2003) igeo class igeo range sediment quality 0 <0 background concentrations 1 0-1 unpolluted 2 1-2 polluted to unpolluted 3 2-3 moderately polluted 4 3-4 moderately to highly polluted 5 4-5 highly polluted 6 >5 very highly polluted calculation of the geochemical metal accumulation index for the oturuba river system returned 269.4 for cu, 2628 for zn, 11.35 for mn, 453.9 for ni, 2.211 for cd and 685.8 for pb. this result therefore places metal concentrations in the study area in the range of very highly polluted sediment environment with only cadmium occurring in moderately polluted status (table 6). conclusions the oturuba river system is a sink for wastes and spills from the artisanal refining, transportation and handling of probably stolen petroleum. these activities have led to elevated levels of heavy metals and hydrocarbon contaminants in sediments of the river. all the sampled sites in the creek had hydrocarbon concentrations that where above limits for total pahs in terms of erl, erm, tel, pel, aet and the dutch intervention values for the protection of ecosystems. however, only the poi (ssa) exceeded the dutch maximum permissible concentrations (mpcs) for mineral oils in both season. the results of this study suggest that levels of hydrocarbons are at concentrations high enough to impair biological communities and are likely to cause toxicity levels that will lead to negative impacts on infaunal communities. also, all the trace elements in the bottom-sediment samples from this study (except vanadium) exceeded the respective tel and/or pel guideline values, which are range where toxic effects occur to benthic organisms (usepa, 1998). heavy metal geochemical accumulation index analysis also returned anomalously high metal concentrations in the range of very highly polluted sediment environment with only cadmium occurring in the moderately polluted status. heavy metal pollution in the oturuba creek has some variability from other river systems in the niger delta region. while concentrations of copper and nickel in the study area is similar to those found in the sediments of the benin river, zinc, vanadium and lead concentrations were far above those found in the same river (akporido and ipeaiyeda, 2014) and in the orogodo river in agbor delta state (issa et al., 2011) all in the far northwester flank of the niger delta. metal concentrations from this study were also very much higher than those found in the bonny river system around okrika (marcus et al., 2013) located not more than twenty kilometres northwest of the study area, while manganese concentrations in the oturuba system were very much above those found in the sediments of the taylor creek system in bayelsa nigeria (okafor and opuene, 2007).these not only shows that the oturuba creek is heavily polluted but that heavy metal pollution of river sediments may be more related to local anthropogenic inputs than terrigenous sources. hydrocarbon concentrations found in the sediments of the oturuba creek were below figures found by akporido and ipeaiyeda (2014) in the sediments of the benin river. also, tph concentrations found in this study were far above that found in the qua iboe river mangrove ecosystem (benson and essien, 2009). this may simply be related to the intensity of oil spill-causing activity in the study area. the potential ecological risk factor (eri) for metals calculated for this study showed that cd contributed more than 98% of ecological risks followed by zn with 14.43%. going by the recommendations of håkanson (1980), the calculated eri for the study area is beyond the baseline for very high ecological risk metal concentrations, thereby ranking the oturuba creek as one of the most polluted coastal river ecosystems in the world; 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(ed.) soil sampling and methods of analysis. lewis publishers, ann arbor, mi. pp. 187–211. ssentongo gw, ukpe et, ajayi to (1986). marine fisheries resources of nigeria: a review of exploited fish stocks. cecaf/ecaf/series, fao, rome, 86/40, pp: 56. usepa, 1992. sediment classification methods compendium. u.s. environmental protection agency, sediment oversight technical committee. office of water (wh-556). epa 823-r-92-006. washington, dc usepa, 1998. the incidence and severity of sediment contamination in surface waters of the united states, volume 1--national sediment survey: u.s. environmental protection agency report 823-r-97-006, various pagination usepa, 1999. understanding oil spills and oil spill response. office of emergency and remedial response. www7.nau.edu/.../oilspill/epaunderstandingoilspillsandoilspillresponse1999.pdf usepa, 2005. predicting toxicity to amphipods from sediment chemistry. epa/600/r-04/030. united states environmental protection agency/ord national center for environmental assessment washington, dc veerasingam, s., venkatachalapathy, r., ramkumar, t. 2012. heavy metals and ecological risk assessment in marine sediments of chennai, india. carpathian journal of earth and environmental sciences 7(2), 111–124. verbruggen e.m.j. 2004. environmental risk limits for mineral oil (total petroleum hydrocarbons). rivm report 601501021/2004. national institute for public health and the environment, bilthoven, the netherlands. walkley, a., black, i.a. 1934. an examination of the degtjareff method for determining organic carbon in soils: effect of variations in digestion conditions and of inorganic soil constituents. soil sci. 63, 251–263. whitehead, a. 2013. interactions between oil-spill pollutants and natural stressors can compound ecotoxicological effects. integrative and comparative biology 53(4): 635–647. doi: 10.1093/icb/ict080. https://scholar.google.co.in/citations?view_op=view_citation&hl=en&user=hlv64i0aaaaj&citation_for_view=hlv64i0aaaaj:zylm7y9caggc https://scholar.google.co.in/citations?view_op=view_citation&hl=en&user=hlv64i0aaaaj&citation_for_view=hlv64i0aaaaj:zylm7y9caggc https://scholar.google.co.in/citations?view_op=view_citation&hl=en&user=hlv64i0aaaaj&citation_for_view=hlv64i0aaaaj:zylm7y9caggc the land use land degradation nexus in mediterranean landscapes – drivers of changes and key processes at selected journal of environmental geography 13 (1–2), 13–24. doi: 10.2478/jengeo-2020-0002 issn 2060-467x the land use land degradation nexus in mediterranean landscapes – drivers of changes and key processes at selected natura 2000 sites of crete, greece burghard c. meyer*, fabian kirsten, dietmar sattler, jürgen heinrich institute of geography, university of leipzig, johannisallee 19a, 04103 leipzig, germany *corresponding author, e-mail: burghard.meyer@uni-leipzig.de research article, received 14 january 2020, accepted 24 march 2020 abstract the land use–land degradation nexus in cretan landscapes in regions with natura 2000 sites was analyzed by an explorative expert driven study based on literature, field work and photo documentation methods with the aim of determining status, drivers and key processes of change. drivers of current land use changes have been worked out by (1) general tourism developments and tourism related land uses; (2) irrigated olive yard developments; (3) fenced large-scale goat pastures and (4) large scale greenhouses. key processes of change have been identified and qualitatively assessed for 5 regions with natura 2000 areas based on a non-ranked set of 11 descriptive indicators. the analysis includes the status-description and the importance assessment of land degradation processes in selected natura 2000 sites. threats and pressures taken from the natura 2000 documentation and the land use – land degradation nexus and the analysis are a suitable basis for future land management in order to reach land degradation neutrality. the result of our analysis opens a new research field for a better integration of the normally thematically isolated analysis in geography, biology/nature conservation and agricultural policy analysis about the drivers and processes in landscape systems towards a better understanding the trends in land cover change (e.g. vegetation/soil degradation), the trends in productivity or functioning changes caused by land uses and as well for the trends in carbon stock change. keywords: integrative land use analysis, landscape change, agriculture, nature conservation, processes of land use change introduction the cretan economy and its landscapes as well as most regions in the mediterranean have been centered on agricultural activities since prehistoric times. subsistence consisted of cereal cropping in lower regions with fertile soils, whereas in mountainous areas animal husbandry, mostly sheep and goat, was the dominating activity and land use. in some areas, a transhumance system was well developed. the land use history of crete has caused widespread and still ongoing soil degradation linked with a transformation of the natural vegetation, processes also dating back to ancient times. locally, the dense mediterranean evergreen and semi-deciduous forests have already been transformed into maquis shrublands and phrygana vegetation in prehistoric times, with an expansion of such areas and further degradation throughout different phases of intense land use (rother 1992). as a result, nearly the entire island of crete can be considered and labeled a cultural landscape. several sites of this old cultural landscape are protected today as natura 2000 sites with high qualities for nature protection (ec 1992). nature conservation, agriculture and tourism are today in a problematic competition for land and water. in order to reach the protection goals of the natura 2000 guideline, a balanced land management is missing to reduce the negative threats and pressures (barredo et al., 2016; dimopoulos et al., 2006; cuttelod et al., 2008; underwood et al., 2009). while agriculture was the dominating activity of the cretan economy until the middle of the 20th century, the touristic sector has become increasingly important in the last fifty years. in the first decades after world war 2, tourists started to visit crete and created some extra income for local farmers, mostly in the dry summer months (donatos and zairis, 1991). however, there was a strong emigration movement, depleting the rural areas of the young generation and workforce. this led to an abandonment of fields and sometimes entire villages, especially in mountainous areas and a reduction in stocking rates and herd numbers (papanastatis et al. 2004; watrous, 1982). besides tourism, agricultural production continues to be an important land use activity. on fertile soils cash crops like olives, citrus and regionally also potatoes have replaced the traditional cereals. although the touristic infrastructure developments are centered on the northern coast, there is a growing competition for land and water between tourism and agriculture on the entire island. as the demand for irrigation for cultivation as well as tourist arrivals concentrate in the dry summer season, the pressure on water resources is especially pronounced. with greece joining the european union (eu) in 1981, the agricultural and the tourism sector developments started to accelerate. eu common agricultural policy (cap) subsidies stimulated and incentivized an increase in numbers and stocking rates of grazing animals (lorent et al. 2009). for example, the number of grazing sheep and goats has increased from 1.56 to 2.51 million in the period 14 meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. from 1980 to 2010 with stocking rates increasing from around 1 to 2.0-2.3 animal units (au) per ha (kosmas et al., 2015). as stocking rates around 1 to 1.5 au/ha are considered appropriate for sustainable grazing, recent stocking rates result in severe overgrazing and an increasing degradation of soils and vegetation (ispikoudis et al., 1993; kairis et al., 2015). subsidies from the european union have also encouraged the intensification of olive cultivation in crete and across the mediterranean, leading to rapid landscape changes from a diverse system to monocropping olive yard structures (allen et al., 2006). in 2017, there were a total number of 27 220 000 olive trees, mostly in compact plantations and under irrigation, on an area of 136 400 ha (hellenic statistical authority 2019). of these, 41 200 ha with 7 850 000 trees have been in use for more than 50 years, while about 10 000 ha containing 2 000 000 trees are only 10 years old or younger. most of these are used for oil production. a new form of agricultural land use is increasingly applied by the construction of greenhouses, where mostly legumes and bananas are grown year-around (karamesouti et al., 2015). due to the long history of intense land use, the mediterranean can be best described as cultural landscapes. it holds valuable assets of culture and nature vital for the cultural land perception and recreation (farina, 2000). with natura 2000 (ec, 1992, further referred to as natura 2000) the eu developed a coherent network of nature protection areas in its member states facing the goal to halt ongoing biodiversity loss by the protection of habitats and species of flora and fauna on terrestrial and marine ecosystems. so far, only few studies have developed management ideas and practices for a future integration of culture and land use in natura 2000 sites by management planning (nk2-group, no year), or for biosphere reserve developments (kusova et al., 2008). even though the cretan natura 2000 special areas of conservation (sac) network seems to be insufficient to ensure at least a satisfactory representation of the regional plant biodiversity (dimitrakopoulos et al., 2005), these areas cover about 17 % of the islands terrestrial area. european management guidelines are available for farming (e.g. on the grazing on high value grasslands) in natura 2000 (ec, 2014) as well as for the forest’s management (ec, 2015). guidelines for land use practices in natura 2000 sites dominated by tourism or recreation important especially on mediterranean islands like crete have not been developed so far. the land degradation neutrality goal (defined by the sustainability development goals) has not yet been specified for landscapes comprising natura 2000 sites in crete, since complex explorative studies are missing. land degradation problems caused by land use, its management and changes, land degradation processes, their determining societal and land drivers and their interlinkages on habitat qualities are generally rarely in the focus of applied research due to their complexity. the aim of the presented explorative study is therefore to work out by literature, photo and expert field analysis important ongoing drivers and processes in landscape systems to determine the status, important to clarify the land use – land degradation nexus in mediterranean landscapes of crete. study areas and methods a number of characteristic cretan landscapes comprising natura 2000 sites were visited during a field campaign in spring 2018 aiming at the clarification and description of critical developments in land use systems including land degradation and depletion of biodiversity (fig. 1, fig. 2). the analysis of respective drivers is based on the authors´ field observation and is as well based and supported by literature and data interpretations of the natura 2000 public database (ec without year). the selection of study areas is based on a general analysis of different landscape types in crete, focusing on landscape ecology, geomorphology, soil, vegetation and land use. the study area selection includes varying land uses in high mountains, lower mountain ranges, forests, abandoned and active arable lands, intensively irrigated arable lands, vineyards, irrigated and non-irrigated olive yards, important cultural sites, villages, tourism facilities, beaches, dunes and multiple mixed landscape configurations as maquis shrublands and phrygana vegetation as well as abandoned terraced landscapes. regions and sites have been selected with the objective to get a major overview of typical current developments within the land use – land degradation nexus, facilitating a better understanding of the status, drivers and active processes potentially causing changes to land and landscape degradation. drivers of land use change potentially affecting study areas are analyzed by varying methods focusing on (1) general tourism developments and tourism related land uses; (2) irrigated olive yard developments; (3) fenced large-scale goat pastures and on (4) large scale greenhouses. these driver’s selection is based on authors expert judgments, on landscape observations, map interpretation and literature. the main methodological approach was structured observations of recent processes and their activity level influencing land degradation based on photodocumentation and field research. for the traditional cretan cultural landscapes, the observations are focused on the processes of depopulation, road infrastructure development, forest fires, overgrazing, water resources in quality/quantity, soil erosion, slope modification, disturbances, habitat fragmentation, land cover change and the abandonment of important cultural landscape elements. due to the complex geology, relief, related climatological conditions and more or less intense anthropogenic modifications, the island of crete is characterized by a large variety of natural and man-made habitats at a comparably small surface area of 8265km², mainly given to the intense elevational gradients of the three main mountain ranges (see fig. 1) and the long history of human presence and activity. the vascular plant flora of crete comprises 2240 species with a level of endemism of 17% and 6,7% alien or non-native species (médail, 2017; turland et al., 1993). with its high level of endemism and high percentage of habitat loss the island is part of the mediterranean biodiversity hotspot (médail and myers, 2005), endangered by continuing habitat destruction and land degradation due to land use meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. 15 intensification (olive groves, goat and sheep overgrazing, tourism), forest fires and biological invasions, e.g. ailanthus altissima, nicotiana glauca and oxalis pescapreae (d´agata et al., 2009) but as well by abandonment of terraces and land use (e.g. followed by forestation and forest succession). crete’s habitat diversity has been partially taken into account in our natura 2000 area selection process, including areas from the shore up to mountainous regions at 2400 m a.s.l. (vogiatziakis et al., 2003). for a first overview survey we selected areas comprising natura 2000 sites in midand western crete ranging from the southwestern coast to the central mountain formations, based on the assumption that all sites are actually affected by more or less strong anthropogenic impacts such as tourism and agricultural land use. other impacts such as water resources exploitation, land levelling for greenhouse cultures, expansion of livestock breeding (e.g. goats, sheep, bees) and infrastructural development measures have also been taken into account. basic information about the natura 2000 features of these areas can be found in table 1a,b, that also include threats and pressures recorded at the moment of the designation of the natura 2000 sites. the selected areas differ considerably with respect to their geological and geomorphological setting, their traditional land use system and settlement pattern as well as their current significance for agricultural production and tourism. the site selection therefore addresses combinations of landscapes, habitats and drivers of degradation being typical and representative for crete. according to dimitriou (2008) and our own observations, the most significant threats for (natural) habitats in crete are i) hydrological alteration due to water overexploitation, artificial drainage and recharge, ii) overgrazing due to the intense stockbreeding practices, iii) water pollution and especially eutrophication originating from unsustainable agricultural practices, iv) solid waste disposal, v) growing and intensified tourism and a lack of legally enforced protection. fig. 1 topography of crete (data source: srtm, openstreetmap). the map shows the rough and diverse topography of crete holding high mountains (white, dark brown), multiple hilly areas (brown) and lowland plains and valleys (green) fig.2 natura 2000 (n2k sites) of crete and analysed n2k study sites (red edging) (1) lasithi plateau, (2) ekvoli geropotamou mesara, (3) lefka ori kai parakti, (4) nisos elafonisos and paralia apo chrysoskalitissa mechri akrotirio krios and (5) giouchtas farangi agias eirinis 16 meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. table 1a threats and pressures of the selected natura 2000 study sites in crete name ( code) dikti: oropedio lasithiou (gr4320002) dytika asterousia (gr4310004) lefka ori kai paraktia (gr4340008) total area (ha) 34007 2651 53364 marine area (%) 0,00 0,00 3,35 n2k type b (habitat directive site) b (habitat directive site) b (habitat directive site) precipitation (mm/y) 900-2200 450-550 500-2800 altitude (m a.s.l.) 800-2148 0-400 0-2443 t h r e a ts a n d p r e ss u r e s: i n si d e ( i) , o u ts id e ( o ), b o th ( b ) a n d r a n k ( h ig h ,m e d iu m ,l o w ) wind energy production ih taking and removal of animals (terrestrial) bh grazing bh genetic pollution (animals) bh outdoor sports, leisure and recreational activities bh improved access to site ih grazing bh/m sand and gravel extraction im hunting and collection of wild animals oh fire (natural) bh/m marine constructions bm trapping, poisoning, poaching of terrestrial animals ih cultivation im dispersed habitation bm other hunting, fishing or collecting activities ih use of biocides, hormones and chemicals im professional passive fishing, netting, spear-fishing bm attraction park ih fertilisation im illegal taking/ removal of marine fauna bm roads, motorways, all paved/ tarred roads im dispersed habitation im camping and caravans, wildlife watching im genetic pollution (plants) im hunting and collection of wild animals om human trampling, overuse, vandalism im erosion im taking and removal of animals (terrestrial) im intensive maintenance of public parcs /cleaning of beaches im sand and gravel extraction il taking / removal of terrestrial plants, general im marine animals death or injury by collision om disposal of household / recreational facility waste il erosion im oil spills in the sea bm outdoor sports and leisure activities, recreational activities il competition bm marine macro-pollution om irrigation il light pollution im artificial planting on open ground (non-native trees) il erosion im forestry clearance, clearcutting, removal of all trees il collapse of terrain, landslide bm removal of forest undergrowth il use of biocides, hormones and chemicals bl discontinuous urbanisation il irrigation bl disposal of household / recreational facility waste il artificial planting on open ground (non-native trees) il walking, horseriding and non-motorised vehicles il car parcs and parking areas il motorised vehicles il diffuse pollution to surface waters due to agricultural and forestry activities bl mountaineering, rock climbing, speleology il inundation (natural processes) il fire and fire suppression bl human induced changes in hydraulic conditions il inundation (natural processes) il meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. 17 table 1b threats and pressures of the selected natura 2000 study sites in crete name (code) nisos elafonisos (gr4340002) paralia apo chrysoskalitissa mechri akrotirio krios (gr4340015) giouchtas (gr4310002) total area (ha) 271 2253 718 marine area (%) 83,73 31,18 0,00 n2k type b (habitat directive site) b (habitat directive site) b (habitat directive site) precipita-tion (mm/y) 450 450 600-800 mm altitude (m a.s.l.) 0-39 0-160 100-808 t h r e a ts a n d p r e ss u r e s: i n si d e ( i) , o u ts id e ( o ), b o th ( b ) a n d r a n k ( h ig h ,m e d iu m ,l o w ) taking / removal of terrestrial plants ih disposal of household / recreational facility waste ih urbanised areas, human habitation ih camping and caravans ih taking / removal of terrestrial plants ih disposal of household / recreational facility waste ih marine constructions bm leisure activities with motorized vehicles ih grazing im dispersed habitation bm camping and caravans ih animal breeding, stock feeding om professional passive net fishing bm genetic pollution (animals) bh restructuring agricultural land holding om leisure spear-fishing bm sand and gravel extraction im artificial planting on open ground (non-native trees) im hunting and collection of wild animals im open cast mining im roads, motorways, all paved/ tarred roads im accidental capture of terrestrial animals bm marine constructions bm mountaineering, rock climbing, recreational cave visits im illegal taking/ removal of marine fauna bm professional passive net fishing bm attraction park im motorized nautical sports bm leisure spear fishing bm vandalism im recreational visits of terrestrial/marine caves bm hunting and collection of wild animals im missing or wrongly directed conservation measures im pollution to surface waters (limnic, terrestrial, marine) bm illegal taking/ removal of marine fauna bm fire and fire suppression im marine water pollution, oil spills in the sea bm motorized nautical sports bm cultivation incl. increase of agricultural area il collapse of terrain, landslide bm recreational visits of terrestrial/marine caves bm use of biocides, hormones and chemicals il sea-level changes bm pollution to surface waters (limnic, terrestrial, marine) bm open cast mining ol marine water pollution, oil spills in the sea bm paths, tracks, cycling tracks il collapse of terrain, landslide bm discontinuous urbanisation ol sea-level changes bm dispersed habitation il continuous and dispersed urbanisation bm/l disposal of inert materials ol grazing il agricultural structures, buildings in the landscape ol hunting and collection of wild animals il taking / removal of terrestrial plants ih disposal of household / recreational facility waste ih urbanised areas, human habitation ih camping and caravans ih taking / removal of terrestrial plants ih disposal of household / recreational facility waste ih marine constructions bm leisure activities with motorized vehicles ih grazing im dispersed habitation bm camping and caravans ih animal breeding, stock feeding om 18 meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. five areas containing natura 2000 sites were selected and analyzed to get an overview of important geo-ecological features, land use and main natura 2000 area qualities (fig. 2). threats and pressures of the selected natura 2000 study sites in crete as described in table 1a and table 1b are taken from the official site descriptions (available by the natura 2000 public database). the same data have been firstly used for the designation of the natura 2000 sites. the database as well includes information about the threats and pressures affecting the sites by differentiating them by their activity inside the site (i), outside the site (o), or in both inside and outside (b) and as well by an importance ranking (high, medium, low) to clarify the importance of the treats and pressures in the respective site context. results: drivers and processes of land use change and land degradation in regions with natura 2000 sites drivers of landscapes and natura 2000 site change four major drivers, all strongly influenced by european policies after the integration of greece into the european union in 1981, have been identified as of major importance on land use change and land degradation in natura 2000 sites and surrounding areas in crete. these are interpreted as general determinants of land use intensification. since the natura 2000 site designation (between the years of 1995 and 2004 and today) the main drivers have been found in (a) tourism developments and to urism related land uses, (b) irrigated olive yard developments, (c) fenced large scale goat pasture systems and (d) large scale greenhouse farming strongly modified the land use systems. all four drivers are influenced by regional development policies and measures including water management measures, agricultural measures in production systems development of the european union as well as by protective settings for natura 2000 development. a rural population decrease of 47 % was measured between 1991-1995 at the southern coast of crete in an investigation area around omalos and samaria gorge (papanastasis et al. 2004). the same process is as well verified for the asterousia mountains by a depopulation of 30 % between 1961 and 2011 (kizos et al.2014). the potential general nexus linking the main drivers via key processes to land degradation is shown in fig.3. the four main drivers of tourism and agricultural developments, irrigated olive yard developments, large scale fenced goat pasturing and greenhouse developments for vegetable production were identified to be the main forces driving the degradation of soil, water, vegetation and landscape components in natura 2000 sites and its surroundings. fig.3 drivers of change influencing selected processes of change and causing land degradation and degradation of cultural landscape qualities in natura 2000 sites and its surroundings of crete the four key drivers influencing the natura 2000 sites can be described as follows: (a) general tourism developments and tourism related land uses: since the 1980s crete has faced an increased tourism development in number and intensity of beach tourism with large scale touristic estate developments especially on the northern coast. organized and individual day tourism increased, mainly in the form of ecotourism e.g. by hiking activities. in peripheral communities this driver leads to the abandonment of settlements, depopulation, habitat fragmentation, water scarcity, direct vegetation and ecosystem modifications and ecosystem destruction as well as increased disturbances in natura 2000 sites (kourgialas et al. 2018, andriotis 2006). see fig. 4a. (b) developments in irrigated olive yards: large scale irrigated olive yard developments in many cretan landscapes have been established on arable land formerly used for rain fed agriculture, on former pasture lands as well as on old terrace systems (karydas et al. 2009, allen et al. 2006; price and nixon 2005, frederic and krahtopodlou 2000). non-irrigated olive cultures have been replaced on a large scale by irrigated olive cultivation. this driver leads to increased water consumption, changes in cultural landscapes and to a strong decrease of the agricultural land use diversity. see fig. 4b. (c) intensive fenced large-scale goat pasture systems: severe vegetation degradation is caused by management changes from extensive shepherds herding of sheep and goats to large scale fenced areas and the concentration on intensive goat husbandry (with external fodder supply throughout the dry months of the year, when winter and early spring vegetation has run out). see fig. 4d. the key degradation driver seems to be overstocking and overgrazing of the open landscapes and a problematic grazing management with sheds, feeding facilities and watering places for the animals (kosmas et al. 2015, kairis et al. 2015, lorent et al. 2009). dispersed extensive grazing of browsing animals is also found in areas of less intensive goat and sheep grazing. meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. 19 (d) large scale greenhouse farming developments: the production of vegetables in greenhouses is an important feature of agricultural intensification stimulated by road developments. see fig. 4c. a strong relief modification by large scale terracing is applied as a baseline for construction; in some places soils and sediments have been excavated from dolines (formerly used for grazing or cereal production) and serve as basic soil substrates in greenhouses (fig. 4e). greenhouse farming has a high water consumption and the applied pesticides, herbicides and nutrients bear the risk of negatively influencing public health (daliakopoulos et al. 2016, tsatsakis et al. 2008, anton et al. 2014) and the natura 2000 area biodiversity qualities. furthermore, pollution with macroand micro-plastics originating from abandoned and degrading greenhouses is affecting both marine and terrestrial ecosystems (gundogdu and cevik 2017). fig.4 major drivers affecting natura 2000 sites – a) tourism development near loutro, western crete; b) irrigated olive yards with terracing, central crete; c) large scale greenhouse agriculture near arvi, southern crete; d) degraded slopes with intensive fenced large-scale goat pastures near elos, western crete; e) soil excavation for greenhouse substrates near elafonisi, western crete important processes observed and identified in the land use change – landscape degradation nexus and described for the selected natura 2000 sites are (see figures 5-7): (1) depopulation of remote villages and single farmsteads leading to abandoned cultural landscapes and conversion into summer houses (fig. 6a), (2) road construction for agricultural, forestry or energy production purposes (fig. 5d), (3) frequent large-scale forest fires causing habitat destruction (fig. 5a), (4) vegetation degradation on pastures and forest vegetation by overgrazing (fig. 5b, 5c and 5e), (5) water resources management measures by intensive water abstraction and modification of water household parameters for irrigation including the desiccation of rivers and water pollution (fig. 6b and 6c), (6) soil erosion caused by overgrazing in fenced goat pastures (fig 6d), in olive yards (fig. 6e) as well as geomorphological surface change by greenhouse construction (fig. 4c), (7) slope modification for the construction of greenhouses (fig. 4e) or irrigated olive yards (fig. 4b), (8) disturbances caused by the increasing individual day tourism (fig. 7b and 7c), (9) habitat fragmentation of landscapes by agricultural, forest and road infrastructure developments (fig. 7a), (10) land cover changes e.g. from extensive pastures to olive yards, pastures to greenhouses and fenced animal husbandry on areas of formerly shepherds herding of goat and sheep (fig 4 in all photos), as well the replacement of grasslands/cereal fields by forests on terraces (fig. 7d), (11) abandonment of characteristic cultural landscape elements including terraces, pathways, stonewalls and former agricultural infrastructure as storage buildings and threshing sites (fig. 7a). fig.5 examples of processes with an impact on land degradation – a) slopes affected by forest fires near kapetaniana, southern crete; b) tree damaged by goat grazing near anopolis, western crete; c) destruction of vegetation in fenced goat and sheep browsing area, central crete; d) country road construction for goat pasture management near anopolis, western crete; e) construction of sheds, watering and fodder places for animals, near anopolis, western crete 20 meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. fig.6 examples of processes with an impact on land degradation – a) depopulated village (kalami, southern crete); b) drowned village (sfendili) in a large-scale water storage facility in northern crete; c) water pond near anogia, central crete; d) soil erosion as a result of goat trampling and overgrazing in ida mountains, central crete; e) olive plantation affected by soil erosion in marly substrates near agia varvara, central crete fig.7 examples of processes with an impact on land degradation – a) habitat fragmentation by construction of infrastructure near livadia, western crete; b) disturbed juniper thicket at kedrodassos beach, western crete; c) parking lots in dune formations for day tourism at elafonisi beach, western crete; d) forest plantations on abandoned traditional terraces near agios ioannis, western crete; e) abandoned traditional threshing site (aloni) near elafonisi, western crete these processes influence the status in the regions analysed in a complex way and are contradictory to the natura 2000 objectives named in the documents submitted to the european commission during the natura 2000 designation process in many cases. the management of these processes should be further detailed as a subject for research based on mapping, process identification and process analysis, process modelling and assessments usable for the regional local and flora/fauna development planning in natura 2000 management, which is still lacking at all sites investigated in this study. status and intensity of land degradation processes in selected natura 2000 sites the analysis of processes influencing land degradation in the five investigated areas is based on literature analysis and field observations during the field work campaign. two summarizing tables are study results by substantiating (i) the drivers affecting the natura 2000 sites studied (table 2) and (ii) the intensity of the observed processes with influence on land degradation and the transformation of the traditional cultural landscapes of crete (table 3). the analysis of factors driving the change and the degradation in the selected natura 2000 sites (table 2) highlights the complexity of landscape intensification processes. direct and indirect forces and processes are often obscure and hard to distinguish. hence, such drivers are rarely considered and in the focus of natura 2000 management activities. table 2 therefore gives the drivers investigated as most important in the studied areas. the activity of key processes with influence on land degradation and the degradation of traditional cultural landscapes (see table 3) is assessed by the authors’ expert judgments and based on field observations. the analysis reveals a complex mosaic of drivers and related processes in the natura 2000 sites. it is based on a wide range of overlaying and interrelated processes (fig.3). all natura 2000 sites and their surroundings face more or less intensive forms of land degradation. nevertheless, processes with impact on the table 1 habitat types are also in interdependences with the processes in the categories of “land degradation” (soil, water and vegetation) and “landscape degradation” (cultural landscape). such complex landscape nexus is not yet clarified and should be subject of further research. natura 2000 area threats and pressures and the land use – land degradation nexus the land use – land degradation nexus analysis based on the threats and pressures taken from the official natura 2000 site characteristic descriptions in table 1a,b (last published update 12/2016) and the drivers and processes of land degradation in crete analysis of our research results in contradictory outcomes. in the following these threats and pressures are shortly interpreted regarding the drivers and processes. while the natura 2000 documentation denotes a set of single threats and pressures per site, our approach tries to address the interlinkages (nexus) of such factors in the context of land degradation. meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. 21 table 2 drivers affecting the selected natura 2000 sites and its surroundings on crete: (1) lasithi plateau, (2) ekvoli geropotamou mesara, (3) lefka ori kai parakti, (4) nisos elafonisos and paralia apo chrysoskalitissa mechri akrotirio krios, (5) giouchtas farangi agias eirinis drivers natura 2000 areas and surroundings 1 2 3 4 5 general tourism developments and tourism related land uses intense day tourism medium tourism pressure by summer and day tourism intense concentration of day tourism activities along samaria gorge, some ecotourism high pressure by day tourism low tourism pressures by sports irrigated olive yard agricultural developments, no direct influence; indirect influence via water uptake strong influence in the wider surroundings no influence multiple new developments strong influence in the surroundings intensive fenced large-scale goat pasture agricultural systems high influence in the surrounding mountains no influence; some extensive grazing of sheep and goat high influence in most areas high influence in the surrounding mountains and on abandoned cultural land few influence, some extensive grazing of sheep and goat large scale greenhouse farming developments no direct influence; indirect via water uptake strong influence in the wider surroundings some developments on coastal sites multiple new developments few developments in the surroundings table 3 activity of processes with influence on land degradation and the degradation of traditional cultural landscapes at the selected natura 2000 sites and its surroundings: (1) lasithi plateau, (2) ekvoli geropotamou mesara, (3) lefka ori kai parakti, (4) nisos elafonisos and paralia apo chrysoskalitissa mechri akrotirio krios, (5) giouchtas farangi agias eirinis actual processes with impact on land degradation natura 2000 areas and surroundings 1 2 3 4 5 depopulation ongoing not visible strong not visible not visible road infrastructure development few strong few strong not visible forest fires in the surrounding not visible strong strong some overgrazing strong in the surroundings not clearly visible very strong very strong strong water resources in quality /quantity extraction of water from the plain strong use of water for irrigation not clearly visible intensive intensive in the surroundings soil erosion water erosion strong in the surroundings wind erosion active active active wind and water erosion some activities, intensive in the surroundings slope modification ponds developments, overall minor multiple modification for divers uses minor modification large scale slope modification and excavation of dolines for olive and greenhouses large scale slope modification for wine and olive disturbances minor by local tourism medium by day and beach tourism high along samaria gorge; low in most of the area very high by day beach tourism few by sport and recreation habitat fragmentation minor high caused by new infrastructure activities medium by activation of old road infrastructure high by road and agricultural activities minor; strong in the surroundings land cover change conversion of grasslands to degraded forest; forest succession diverse local changes, multiple abandoned sites partly military sites enlargement of forest areas; change to irrigated olive yards and greenhouses; multiple abandoned sites, some tourism infrastructure, abandoned water infrastructure forest succession on former terraces abandonment of important cultural landscape elements windmills, divers water pump infrastructure, flooded pastures old olive orchards, extensive arable land (cereal production) pasture of dunes terraces, historical paths network, stonewalls around arable former arable fields, old olive orchards, threshing sites threshing sites, extensive doline land grazing, extensive arable land (cereal production) pastures, orchards, terraces on lower slopes 22 meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. the threats and pressures information in the documentation mentioned above is qualitatively described and ranked and attributed with importance levels (high/medium/low) in table 1a,b. the currentness of the information is not clarified as the threats and pressures may relate to the moment of first reporting for the foundation of the cretan natura 2000 sites. the documentation states important and significant information on highly ranked (important) pressures and threats such as grazing, erosion, fire, fertilization or taking and removal of terrestrial plants. this information is usable as general information about impacts on the habitat types. the land use intensity changes related to agriculture, tourism and infrastructure have been identified as important drivers of degradation of various habitat types in crete, comparable to and observed in other mediterranean landscapes (dimopoulos et al. 2006; cuttelod et al. 2008; underwood et al. 2009). nevertheless, a comparison of status and intensity of land degradation in selected natura 2000 sites and of the respective effects of different land uses as described above is difficult as long as detailed model analysis and more statistical data are lacking. the comparison of major threats stated in the natura 2000 documentation and the authors’ field observations explained in sections above by the drivers effecting natura 2000 sites and its surroundings on crete reveals some open fields of problem analysis for a better understanding of the land use – land degradation nexus compared with the natura 2000 documentation: (1) the general touristic developments and tourism related land use activities are often named as threats and pressures in the natura 2000 documentation without a management goal formulation or related protective measures as subject of the still missing management planning; (2) the irrigated olive yard agricultural developments are not named as a threat or pressure; (3) the large-scale fenced goat pastures are named a as threat and pressure by overgrazing and animal breeding, agricultural structures, new agricultural buildings (e.g. sheds in the landscape) in most of the natura 2000 sites; (4) large-scale greenhouse farming as well as the road infrastructure developments as a problem of habitat fragmentation are not a subject of threats and pressures documentation for natura 2000 sites. landscape degradation processes in the mediterranean landscapes the list of current processes determined by land uses with impact on land degradation with importance on landscape, vegetation, soil and water systems is interpreted by the authors as a missing link or knowledge gap for a better understanding of the regeneration potential of mediterranean landscapes. land degradation is defined by the united nations convention to combat desertification (unccd 1994) convention as “a reduction or loss, in arid, semi-arid and dry sub-humid areas, of the biological or economic productivity and complexity of rain fed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as: soil erosion caused by wind and/or water; deterioration of the physical, chemical and biological or economic properties of soil; and long-term loss of natural vegetation”. when focussing on the degradation of cultural landscapes and by widening the definition from land degradation analysis towards the analysis of the landscape degradation “as an irreversible or non-resilient system change to a landscape that affects the landscape system components (i.e., their geo-factors, land use and inter-linkages) and the natural and cultural capacities of the landscape (productive, ecological and social structure, processes and landscape functions” (meyer et al. 2017), the focus of such an analysis in the mediterranean should be widened into the landscape context e.g. on the economically very important tourism and agricultural intensification developments in the cretan context – into a new land use and landscape pattern and landscape configuration perspective. for both land degradation and landscape degradation analysis of the soil, water and vegetation degradation is required since the authors observations on revegetation, e.g. after fire events in degraded limestone landscapes, shows a fast renewal of the former, mostly already modified status of the phrygana vegetation. a new view on the degradation problem in the mediterranean is needed since the changes in the intensity of land uses are not known in a landscape systems context. the land use / landscape changes influencing the natura 2000 sites are determined by general and external factors as changes in agricultural or regional policies, management techniques, land use measures and practices interpreted in our study as land use intensity changes. a degradation of vegetation types listed in habitat directive (council directive 92/43/eec) was found during the field analysis. a system degradation of water management facilities is observed by abandoned irrigation systems and strongly modified surface waters of the karst water systems and multiple other water related infrastructure measures. soil degradation is obviously found in areas of land and slope surface change by terrace abandonment, active and former erosion gullies, and geomorphologic levelling for greenhouses and by soil abstraction. landscape degradation is interpreted by the conversion of abandoned or extensive cultural landscape features to a more industrial and less diverse land use pattern, especially by olive yard plantation. problematic intensification practices of bee keeping and honey production were observed in the analysed natura 2000 sites by the introduction of scale insects on pine trees providing a continuous nectar source throughout the entire year. this practice results in local dieback of entire pine tree populations and potentially increases forest fire risk. conclusion the land use – land degradation nexus in mediterranean landscapes was analysed by status, drivers and key pressures using the example of selected areas comprising natura 2000 sites. the changing land use intensity e.g. in the fenced large-scale goat pasture systems may meyer et al. 2020 / journal of environmental geography 13 (1–2), 13–24. 23 promote further and strong vegetation degradation and is of importance regarding the degradation of soil and water resources. the large-scale greenhouse developments and the irrigated olive yard developments are primarily driving degradation pressures in the landscape context but also lead to degradation of water, soil and vegetation resources. the tourism developments and tourism related land uses including road developments have a significant impact on landscape degradation and may have influence the depletion of vegetation, water and soil resources. further analysis is needed for a more complex identification of land degradation within the land use intensity context. the critical limits/levels or thresholds of the observed land degradation are not yet fully known and the respective interpretation of landscape degradation needs to be revised as well. detailed research is needed for a better understanding of the land use – land degradation nexus in mediterranean landscapes especially for karst landscapes since degradation processes are less known for soils developed on calcareous rocks, as well as their potential of natural and managed revegetation is not yet scientifically clarified. the land degradation neutrality goal of the un has to be investigated, measured and analysed by 3 key indicators: (i) by the trends in land cover, (ii) by the trends in land productivity or functioning of the land and (iii) by trends in above and below ground carbon stocks (iucn 2015). based on the results of the presented study we suggest that future research on land degradation should lay a stronger emphasis on trends in land use and land cover developments as drivers of change and as a basis for the analysis of the temporal changes in the vegetation, water, soil and cultural landscape systems. at the same time, it is important to understand how the multiple related processes/pressures and threats identified in this study influence land productivity and carbon stocks in the context of climate change. the aim of the presented explorative study has been to work out by literature, photo and expert field analysis important drivers and ongoing processes in landscape systems to clarify the land use – land degradation nexus in mediterranean landscapes of crete. next steps should be developed towards a better and integrative analysis and description of the sensitivity of the landscapes and its patches and by the determination of thresholds to clarifying the processes changes. methods used in the expert approach in our study by the example of crete should be further specified by diverse data sets for a better process description and by model developments applicable for policy and planning advice. acknowledgement we thank susann heinrich for the fruitful discussion and the two anonymous reviewers for the helpful comments. references allen, h. d., randall, r. e., amable, g. s., and devereux, b. j. 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(1982). lasithi: a history of settlement on a highland plain in crete. hesperia suppl: vol. 18. princeton, nj: american school of class. studies at athens. introduction study areas and methods results: drivers and processes of land use change and land degradation in regions with natura 2000 sites drivers of landscapes and natura 2000 site change status and intensity of land degradation processes in selected natura 2000 sites natura 2000 area threats and pressures and the land use – land degradation nexus landscape degradation processes in the mediterranean landscapes acknowledgement references journal of environmental geography journal of environmental geography 10 (1–2), 41–51. doi: 10.1515/jengeo-2017-0005 issn: 2060-467x centurial changes in the depth conditions of a regulated river: case study of the lower tisza river, hungary gabriel jonathan amissah1*, timea kiss1, károly fiala2 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2lower tisza district water directorate, stefánia 4, h-6720 szeged, hungary *corresponding author, e-mail: gabbyjonad@yahoo.com research article, received 1 march 2017, accepted 26 may 2017 abstract the tisza river is the largest tributary of the danube in central europe, and has been subjected to various human interventions including cutoffs to increase the slope, construction of levees to restrict the floodplain, and construction of groynes and revetments to stabilize the channel. these interventions have altered the natural morphological evolution of the river. the aim of the study is to assess the impacts of these engineering works, employing hydrological surveys of 36 cross sections (vo) of the lower tisza river for the years of 1891, 1931, 1961, 1976 and 1999. the changes in mean depth and thalweg depth were studied in detail comparing three reaches of the studied section. in general, the thalweg incised during the studied period (1891-1931: 3 cm/y; 1931-1961: 1.3 cm/y and 1976-1999: 2.3 cm/y), except from 1961-1976 which was characterized by aggradation (2 cm/y). the mean depth increased, referring to an overall deepening of the river during the whole period (1891-1931: 1.4 cm/y; 1931-1961: 1.2 cm/y; 1961-1976: 0.6 cm/y and 1976-1999: 1.6 cm/y). the thalweg shifted more in the upper reach showing less stabile channel, while the middle and lower reaches had more stable thalweg. although the cross-sections subjected to various human interventions experienced considerable incision in the short-term, the cross-sections free from direct human impact experienced the largest incision from 1891-1999, especially along the meandering sections. keywords: thalweg, channel depth, lower tisza river, river regulation, morphological changes introduction rivers have been altered by human impacts for centuries for economic benefits (flood protection, improvement of shipping routes, energy production, water withdrawal etc.). it is important to understand the consequences of these interventions, since such hydro-morphological and ecological information are crucial to any sustainable future river engineering (hooke, 1995). the sediment load and its characteristics reflect the overlapped effects of all environmental subsystems of the river’s catchment (fryirs and brierly, 2001; fryirs et al., 2007, 2008). if, any of these subsystems change, it should be reflected in the sediment transport, thus in the channel forms of a river (chruch, 2006; anderson and anderson, 2010; hassanzadeh, 2012). therefore, alluvial channel morphology is the result of the interactions between channel-bed topography, flow field and sediment movement (van der berg, 1995; ferguson, 2010; latapie et al., 2014; leigleiter, 2014; powell, 2014). although rivers are natural transporters and exporters of sediments, usually direct human activities on the channel adversely affect this capacity (yang et al. 2014). the different human impacts have increasingly reduced the amount of transported sediments, as usually they trap or dredge the sediments i.e. by channel straightening, embanking, widening, removal of riparian vegetation and urbanization (osei et al. 2015). when these artificial modifications aim to change the channel itself, they are defined as direct human impacts, and include channelization, widening, bank protection, mining and removal of riparian vegetation (brierly and fryirs, 2005). on the other hand, when the interventions are not carried out directly on the river but involve the modification of the subsystems within the catchment, and they affect the flow and sediment transfer regime of a river, they are termed as indirect human impacts (e.g. deforestation, land use changes, mining activities and urbanization). these indirect impacts are characterized by spatial and temporal lags of varying intensities. the consequences of these human interventions have been well described on various rivers in the world (rinaldi and simon, 1998; surian, 1999; liébault and piegay, 2001; kondolf et al., 2002; xu, 2002; rinaldi, 2003; yates et al., 2003; antonelli et al., 2004; harmar et al., 2005; pinter and heine, 2005; chang, 2008; kroes and kraemer, 2013; kiss and balogh, 2015; morais et al., 2016; nagy and kiss, 2016). the riverbeds are quite sensitive to any modification of discharge and sediment supply within the catchment. while the diversion and/or extraction of water from the channel induce aggradation, constructions (e.g. levees and 42 amissah et al. (2017) embankments) increase flow velocity and induce scouring (landon et al., 1998; gregory, 2006; huang et al., 2014). most european rivers flowed in wide braided channels in the 19th century. however, the 20th century ushered in various forms of human interventions and the concomitant decrease in sediment supply to the channels, therefore most rivers started to narrow and incise (liébault and piegay, 2002; rinaldi, 2003; surian and rinaldi, 2003; liébault et al., 2005; rinaldi et al., 2005; wyżga, 2007). in the carpathian basin, diverse direct and indirect human impacts altered the morphology of the tisza river, which is the second largest river of hungary. in the 21st century rising flood water levels were recorded on the tisza river. it could be explained by the catchment-scale runoff increase due to forest clearance, rough grazing, land-use changes, and probably increasing mining and quarrying activities on the catchment (schweitzer, 2009). besides these decadal and centurial catchment-scale indirect human impacts, engineering alteration of the channel itself was also responsible for the increasing flood levels. the primary aim of the works was to protect towns and villages, infrastructure and agricultural lands from floods and to support shipping. therefore, in the late 19th century a system of artificial levees along the tisza river and tributaries were built, meanders were cut off, new artificial channels were made, and swampy areas were drained by creating drainage canals (schweitzer, 2009). the superimposed effects of these indirect and direct human impacts had changed the hydrology and morphology of the river. although studies have been made to ascertain the impacts of these regulation works, only a short reach of the tisza river was studied in detail and covered various elements of the channel (sipos et al., 2007; kiss et al., 2008). with this study, our goal is to assess the impact of artificial cut-offs and revetment constructions on the depth conditions of the entire lower tisza river (ca. 90 km long) channel, highlighting thalweg depth changes between 1891 and 1999. study area the tisza river (catchment area: 157200 km2, length: 962 km; lászlóffy, 1982) is the main tributary of the danube in hungary. with its source in the north-eastern carpathian mountains, it drains the eastern part of the carpathian basin flowing through the great hungarian plain. the hungarian section of the tisza (l: 596 km, a: 47000km2) is divided into three sections. the studied lower tisza river (fig. 1) stretches from upstream of csongrád (255 f.km) to the hungarianserbian border (166 f.km). based on the degree of human impact and the morphological characteristics, the section was divided into three reaches (table 1). along the lower tisza the pre-regulation slope (2.2 cm/km) was increased to 2.9 cm/km by artificial cut-offs. the maros river, which is the major tributary of the tisza, has a high-slope (13 cm/km) in its lowland section, thus downstream of their confluence at szeged the slope of the tisza increases to 6 cm/km (kiss et al., 2008; mezősi, 2009). the tisza in hungary has a typical lowland river character, as it transports large amount of fine grained sandy and silty suspended sediment and it has a clayey bed material (lászlóffy, 1982; mezősi, 2009; kasse et al., 2010). fig. 1 the studied tisza section was divided into three reaches based on the morphology of the channel. the studied crosssections (1-upper reach; 2-middle reach; 3-lower reach) and cut-offs are also indicated. table 1 characteristics of the three river reaches evaluated in this study reach length (f.km) floodplain width cut-off (no.) revetments min mean max length (km) density (km/km) upper 255-238 365 850 1060 3 10.92 0.64 middle 238-194 560 1000 3200 7 17.53 0.39 lower 194-166 380 600 975 2 16.03 0.54 centurial changes in the depth conditions of a regulated river… 43 hydrology the catchment of the tisza has an annual mean precipitation of 744 mm/y, thus the generated mean run-off is 177 mm/y (mean discharge: 830 m3/s; icpdr, 2008). on the tisza, usually two major floods occur. the first flood (marchapril) is caused by snow melt, and if the snowmelt is combined with rainfall extremely large floods could develop. the second flood occurs during the summer (june), induced by the early summer rainfall. as the lowland section of the river is long, and its slope is small, this summer flood sometimes superimposes on the preceding spring flood, thus record high floods could develop. the absolute water level change between the highest and lowest water stages is 1355 cm at mindszent (highest stage measured in 2006: 1062 cm; lowest stage measured in 1968: -293 cm), and 1184 cm at szeged (highest stage measured in 2006: 960 cm; lowest stage measured in 1968: -224 cm). the discharge also shows considerable hydrological variations. at szeged, the maximum discharge is 4348 m3/s (in 1932) and minimum value is 58 m3/s (in 2013; lóczy et al., 2009; kiss, 2014). regulation works the late 19th century marked the beginning of catchmentscale engineering interventions on the tisza river. they involved the disconnection of the tisza from its wetlands by construction of levees. the flood control levee-system is 2940 km long, and the originally 27000 km2 large natural floodplain (which was about a third of the territory of hungary) was reduced to 21251 km2. the aim of artificial levee constructions was to protect the land from inundations and to provide safe areas for agriculture, and to decrease the duration of floods (szlávik, 2000; pinke, 2014). simultaneously, the river was shortened by 38% with 114 meander cut-offs (dunka et al, 1996; schweitzer, 2009). as a result of cut-offs, the meandering equilibrium river was transformed into an in-growing meandering one, as its slope almost doubled (kiss, 2014). the cut-offs accelerated the erosion of the river bed, thus the sediment load increased, which resulted in accelerated deposition on the confined active floodplains (kiss et al., 2011). the regulation works in the 20th century continued by the construction of revetments and groynes. revetments were built to stop the lateral erosion of bends which migrated too close to levees, whilst the groynes facilitated shipping by tightening wide sections and to train sharp bends in order to improve the flood conductivity of the river channel. in total 44% of the banks of the tisza river were stabilized, mainly between the 1930s and 1960s. however, it started in 1886, whilst the latest was built in 2016. the second half of the 20th century was the period of dam constructions on tisza and its tributaries. on the tisza, three dams (which operate as locks) were built at tiszalök (1957) and kisköre (1973) in hungary, and törökbecse/novi becsej (1976) in serbia (bezdán, 2010). the locks were built to impound the water during low stages, thus water withdrawal for irrigation could be secured, but they also produce hydropower and aid navigation. although they are opened during floods, the retention of sediments by the dam creates temporal sediment deficit downstream which induces incision (kiss et al., 2008; lóczy et al., 2009). along the lower tisza channel regulations started in 1855, shortening the originally 131 km long studied river section by 30 km, cutting off 12 meanders. the originally 6–8 km wide natural floodplain was reduced to 1 km in average. at szeged however, the floodplain is just 400 m wide. the levees constricted the floodplain at some sections, thereby reducing its flood conductivity and increasing the flood risk. therefore, the height of levees was increased too: originally they were just 2.3–3.0 m high, but nowadays their height is 7.0 m, thus they could provide safety despite of the increasing flood levels (sipos et al., 2007; kiss et al., 2008; lóczy et al., 2009; schweitzer, 2009). in the lower tisza 51.4% of the banks are protected by revetments, but their spatial distribution is not even, as it is indicated by the different revetment density of the studied reaches (table 1). materials and methods to understand the channel depth changes caused by direct human impacts, the maximum and mean depths along cross-sectional profiles were measured and analyzed. the study employed a dataset of hydrological surveys made in 1891, 1931, 1961, 1976 and 1999. the hydrological atlas of the lower tisza (1974) provided the locations of the surveyed cross-sections and it also showed the bank lines of the river at different dates. the channel surveys were undertaken using fixed geodetic survey points (vo-stones) at approximate spacing of 2.5 km. these vo-stones allowed subsequent surveys at the same cross-sectional profiles at different times. along a profile the channel depth was measured at 5 m intervals. in the present study relative depths were calculated from the bankfull level, which was determined as lowest point of the bank line (fig. 2). based on the cross-sectional profiles the maximum (thalweg) depth and the mean depth for every cross-section were determined. the maximum depth refers to the location of the thalweg. the mean depth was calculated as the arithmetic mean of all depth data of a cross-section. fig. 2 the depth values were measured from the bankfull level of a cross-section the spatial data of cut-offs and revetments were provided by hungarian lower tisza water directorate. in the study bends and meanders were distinguished, based on laczay’s classification (laczay, 1982). the sinuosity 44 amissah et al. (2017) of segments was calculated between two inflection points, as the ratio of bend length and chord length (fig 3). if the sinuosity value was below 1.1, the segment was classified as a bend, if it was above 1.1 the segment was considered to be a meander. fig. 3 determination of inflection points, bend length and chord length along the segments of the river results and discussion the presented results include the changes in characteristic depths of the study section, the spatio-temporal variation of the thalweg, and its relative position to the nearest bank. the influence of the various human interventions was also evaluated by comparing the thalweg depth of channel segments influenced by direct and indirect human impact. a general overview of the studied 36 cross-sections (fig. 4) indicates that 64% of them are located in slightly sinuous bends, whilst the remaining 36% are situated in meanders. also, ca. two-third of the cross-sections was under some kind of direct human influence, and only onethird (13) of them is free from direct engineering works, indicating heavy anthropogenic impact on the lower tisza river. the cross-sections free from any direct regu changes in mean depth of the channel the mean channel depth gives an indication of the general bed level change of a cross-section, and thus of the studied segments and reaches. the yearly mean depth changes representative for the entire studied lower tisza, indicate incision for all periods (1891-1931: 1.4 cm/y; 1931-1961: 1.2 cm/y; 1961-1976: 0.6 cm/y; and 1976-1999: 1.6 cm/y). the intensive incision of the channel in the first period could be explained by the effect of the cut-offs. the incision continued in the next period (1931-1961) too, though the incision rate reduced by 14%, and this reduction further continued but in a greater extent (50%) between 1961 and 1976. this general reduction in the mean depth of the whole section can be attributed to the gradual evolution of the channel after the first phase of the regulation works towards an equilibrium state. however, in the last period (1976-1999) the channel experienced its highest yearly incision rate. this could be explained by the construction of the revetments which restricted the lateral erosion of the river. this meant the channel could undergo incision readily which resulted in higher incision rate by 1.5 times. a more detailed analysis of the changes of the mean depth along the studied section (fig. 5) shows that the location of the greatest incision rates changed by time. while between 1891 and 1931 the greatest incision (12 cm/y) appeared on the upper reach (vo 200), in the next period between 1931 and 1961, it was in the lower reach (10.5 cm/y, vo 225). between 1961 and 1976, it was measured in the upper reach (14.1 cm/y, vo 207), and finally the incision rate was 9.5 cm/y between 1976 and 1999 which occurred in the middle reach (vo 214). the vo 200 probably incised in response to cut-offs since it is located within an artificial channel, however the remaining sections were all located within meanders. although most cross-sections referred to incision, some cross-sections had higher incision rates. the period 1976-1999 had its highest aggradation (15.9 cm/y) in the middle reach. t he highest rates of aggradation for all the other periods (1891 1931: 8.7 cm/y; 1931-1961: 6.9 cm/y; and 1961-1976: 12.8 cm/y) occurred in the lower reach. the ratio of the mean depth to the thalweg depth along the studied section of the river (fig. 6) was also calculated, as it refers to the difference between the mean fig. 4 the studied cross-sections are located in meanders or bends, and various human interventions affected most of their development centurial changes in the depth conditions of a regulated river… 45 depth and the thalweg depth: smaller value indicates a greater difference between the thalweg depth and mean depth. the ratio of mean and thalweg depths generally decrease from upstream to downstream (0.70 for upper reach; 0.69 for middle reach; and 0.67 for lower reach), referring to a more even channel bottom towards downstream. however, considering the temporal changes, it is interesting, that the ratio generally increases, referring to more intensive incision of the thalweg itself, than of the bottom of the whole channel. changes in the depth of the thalweg during the studied period the mean thalweg depth of the whole studied section increased from 12.2 m (1891) to 14.1 m (1999), thus by 15.5 %, representing an incision rate of 1.7 cm/y over a century and indicating a general thalweg incision (fig. 7-9). however, the incision of the thalweg was not temporally an even process, as at the beginning (1891-1931) the mean thalweg depth increased by 1.2 m which represents an incision rate of 3 cm/y. this incision continued (1931-1961), although its rate became lower (1.3 cm/y). finally, between 1961 and 1976 the thalweg was subjected to aggradation resulting in the reduction of the mean thalweg depth by 0.3 m (aggradation rate: 2 cm/y). this virtually negated the incision of the previous period. between 1976 and 1999 the thalweg again experienced incision (2.3 cm/y). these changes could be explained by the human impacts on the studied section: the cut-offs which shortened the channel length caused an increase in bed slope, which resulted in stream power increase. the initial high incision rate could be attributed to the quest of the river to re-establish its equilibrium after the cut-offs. fig. 5 changes in mean depth: the mean depth at the beginning of a period between two surveys indicated by blue line; and the yearly change in mean depth in between survey years is indicated by red columns fig. 6 the variation of the ratio of the mean depth to thalweg along the studied section 46 amissah et al. (2017) fig.7 variations in mean thalweg depth for the whole studied section as the channel gradually developed towards quasi-equilibrium, the incision reduced (1931-1961), and the channel evolution process culminated in aggradation (1961-1976), similarly to the stages of the channel evolution model of simon and rinaldi (2006). the effect of high floods in the late 20th and early 21st centuries was combined with the effects of revetment and groin constructions, therefore the thalweg started to incise, thus the evolution model distorted. the range (i.e. the difference between the maximum and minimum thalweg depths) was up to 14.2 m in 1891. an increasing minimum thalweg depth and a decreasing maximum thalweg depth caused a reduction in the range until 1961. afterwards this trend reversed, thus the range increased (1999: 12 m) was still short of the 1891 value. this reduction in ranges points to the development of a uniform channel, implying that although the channel was progressing to equilibrium after the cut-offs, the construction of the revetments and groynes initiated another cycle of dis-equilibrium. fig. 8 variation of thalweg depth along the studied section for various survey years the spatio-temporal changes of the thalweg were studied comparing the three reaches of the lower tisza. the upper and middle reaches show significant changes in thalweg depth, while in the lower reach the thalweg remained relatively stable (fig. 8). this could be explained by (i) the ponding effect of the danube and maros rivers on the tisza (vágás, 1982) and by (ii) the artificially more stabilized and straightened lower reach. the areas of maximum incision along the channel occur mainly downstream of the cut-offs. this means the scouring action of the increased fig. 9 changes in thalweg depth: the thalweg depth at the beginning of a period between two surveys is indicated by red line, and the yearly change in thalweg depth in between survey years is indicated by blue columns centurial changes in the depth conditions of a regulated river… 47 stream power was more pronounced at the end of the artificial segments (cut-offs) of the river channel. the location of the thalweg within the cross-sectional profile was studied in detail too: the greater the ratio between the location of the thalweg to the closest bank and the channel width, the farthest is the thalweg to the banks (fig 10). considering the whole, ca. 100 year-long period, it seems that the thalweg migrated closer to the banks in the upper reach, whilst the changes within the middle reach are smaller, and in the lower reach the thalweg migrated away from the bank. the trends also show that the location of the thalweg had the greatest range of variations in the upper reach, referring to frequent thalweg changes: in some crosssectional profiles the thalweg shifted almost across half of the channel width. although along the middle reach at some cross-sections the thalweg shifts were very small, in general the lower reach had the narrowest range. this implies the lower reach was more stable compared to the middle and upper reaches, although there were some very stable locations within the middle reach. fig. 10 variation of the thalweg location relative to the whole cross-section width (the shaded area refers to the range of changes in the position of the thalweg) the mean thalweg depth values of the upper reach were generally lower than the whole section, and the deepest thalweg depth was characteristic of the lower reach. the incision of the thalweg depth of the three different reaches (fig. 11) during the whole period reflects an increasing trend towards downstream, as the mean depth of the thalweg increased by 1.3 m (1.2 cm/y) in the upper reach, by 1.7 m (1.6 cm/y) in the middle and 2.5 m (2.3 cm/y) in the lower reach. effect of human impacts on the evolution of the thalweg depth to evaluate the role of engineering works on channel evolution, the channel segments not affected directly by cutoffs and revetments were compared to segments created by cut-offs and affected by revetments. effect of cut-offs at the beginning, the mean thalweg depth in non cut-off segments was 11.7 m, while it was 13.7 m in artificial segments (fig. 12). the higher mean thalweg depth in the artificial segments could be attributed to the initial scouring induced by the artificial channels of the cut-offs. however, by 1999, the mean thalweg depth in the non cut-off segments had increased by 21% to 14.2 m (2.3 cm/y), while in case of artificial segments almost zero net change was recorded. with the exception of 1961-1976 when the channel experienced a general aggradation, there was consistent incision of the mean thalweg depth within the non cut-off segments. in the artificial segments, although there was no net change between 1891 and 1999, there was a depth increase of 0.9 m from 1891 to 1931 (2.2 cm/y), which was followed by a consistent reduction of mean thalweg depth (1931-1961: 1.3 cm/y; 1961-1976: 2 cm/y and 1976-1999: 0.9 cm/y). the incision within the non-cut-off segments are partly due to the construction of revetments (80% of revetments built in segments which were not created by cut-offs) which restricted the lateral erosion within the channel, and therefore increased fig. 12 comparison of mean thalweg depths for cross-sections within segments affected and not affected by cut-offs, including the range (maximum-minimum) of thalweg depths fig. 11 variations in thalweg depth values within the various reaches 48 amissah et al. (2017) scouring of the channel bed to complement the sediment deficiency. another important factor is the location of a cross-section within a meander or bend. for an alluvial channel, due to the asymmetric nature of cross-sections in meanders, thalweg depths are generally deeper in meanders than in bends or straight segments (dey, 2014). this statement is also valid for the lower tisza (fig. 13), as the mean thalweg depth of meandering segments is deeper by 3 m than of the non-meandering segments. within the studied section, more than 90% of the meanders are located in the non-cut-off segments which contributed to its depth increments. however, the relatively narrower widths of the artificial channels also meant that the channel had the tendency to scour with the initially high stream power. fig. 13 comparison of mean thalweg depths for cross-sections within meanders and bends, including the range (maximum-minimum) of thalweg depths the mean thalweg depth within the reaches followed similar trends as of the entire section for both the non cut-off and cut-off segments (fig. 14-15) although the magnitude in the depth changes was different. for the non cut-off segments, the upper reach had the least mean depths, and the lower reach had the highest magnitudes in mean thalweg depth. in case of artificial segments, decreasing temporal trends were found in the upper and middle reaches. however, in the lower reach, there was an increasing trend in mean thalweg depth values. another important observation is the relatively larger ranges in the non cut -off segments compared with the artificial segments. effect of revetments and groynes when evaluating the effects of revetments and groynes in the development of the thalweg depth, it should not be forgotten, that only the combined effect of revetments, groynes and cut-offs could be studied, as they are located very close to each other, and also temporally the responses of the river on these interventions overlap. the comparison of segments without any direct human impact to the artificially altered ones reflect very similar the trends, although the segments with human impacts tend to have smaller ranges (fig. 16). this is understandable due to the fa ct that they were artificially created, therefore more evenly engineered than the natural development of the non affected channel segments. this creates more uniformity within the artificial segments compared to the natural channel segments. fig. 14 variations of the mean thalweg depth within non cut-off segments fig.15 variations of the mean thalweg depth within artificial segments created by cut-offs centurial changes in the depth conditions of a regulated river… 49 focusing on the reaches, the three reaches do not exhibit similar patterns (fig. 17-18). the absence of clear trends shows the deficiency of generalization to responses of human impacts by rivers in some cases. fig. 16 comparison of cross-sections with and without direct human impacts conclusion the study analyzed the changes in mean depth and thalweg depth of the lower tisza river from 1891 to 1999, focusing on the role of direct human impacts (mainly regulation works) in their evolution. simon and rinaldi (2006) indicated that degradation of cha nnel beds represents a response to a disturbance in which an excess of flow energy, shear stress or stream power (sediment-transporting capacity) occurs relative to the amount of sediment supplied to the stream. the results indicate that between 1891 and 1 999, the mean depth of the channel increased as a response to human interventions and this is trend is similar to the response of rivers in italy to various interventions with some incising by up to 10 m (surian and rinaldi, 2003). using the periods in between the surveys as reference periods, the highest rate of incision occurred immediately after human interventions, similarly to european and north american rivers, which also showed considerable adjustments immediately after human interventions (smith and winkley, 1996; surian and rinaldi, 2003). as a fluvial response on mid and late-19th century cut-offs the incision accelerated in the period of 1891-1931, whilst the revetment and groynes constructions of the 1930 -1960s increased further the channel depth between 1976 and 1999. the evolution of the thalweg depth shows that in the periods of 1891-1931, 1931-1961 and 1976-1999, the channel experienced incision while during 1961 1976 it was characterized by aggradation. it marks the attainment of equilibrium before the river readjusted to the construction of revetments. the mean thalweg depths in the upper reach were lower than the mean for the entire section with the highest values referring to the lower reach. the mean depth of the thalweg generally increased from upstream to downstream. acknowledgements the research was supported by the stipendium hungaricum programme and the hungarian research foundation (otka 119193). data were provided by the water directorate of the lower tisza district (ativizig). fig. 17 variation of the mean thalweg depth for the sections without direct human impact fig. 18 variation of the mean thalweg depth for the sections with direct human impact 50 amissah et al. 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environmental geography journal of environmental geography 8 (1–2), 49–58. doi: 10.1515/jengeo-2015-0006 issn: 2060-467x modelling runoff on a small lowland catchment, hungarian great plains tamás právetz 1* , györgy sipos 1 , balázs benyhe 2 , viktória blanka 1 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 lower-tisza water directorate, stefánia 4, h-6720 szeged, hungary *corresponding author, e-mail: pravetz@gmail.com research article, received 1 april 2015, accepted 20 june 2015 abstract the lowland region of the south-eastern carpathian basin faces extreme hydrological conditions, therefore the more detailed understanding, monitoring and predicting of the hydrological regime on catchments have high importance. however, in the region only few measured data are available in terms of evaporation, runoff, infiltration and water retention, and this is especially true concerning small catchments. in the meantime these areas support extensive agriculture, therefore more information is needed to manage future drying and irrigational demands. in the present research runoff and discharge were modelled for a ten year period and compared to at-a-station measurement data on the fehértó-majsa canal, a sub-catchment of the tisza river, in order to test the predictability of hydrological changes related to future climate change. modelling was made by applying a coupled mike she/mike 11 model and integrating all available topographic, pedologic, climatic, hydrologic and vegetation data. consequently, another motivation of the research was to assess the suitability, data demand and limitations of the mike modelling environment on lowland catchments. as from all available data sources soil data seemed to be the least accurate, sensitivity tests were made by changing different soil parameter. based on the results, the developed model is highly suitable for the estimation of annual and monthly runoff. nevertheless, concerning daily data a general overestimation of discharge was experienced during low flow periods, and a time lag appeared between measured and modelled discharge peaks during high flow periods. in all, the results of the study can greatly support the realization of water management and planning projects in the drought prone sand land catchments where only a few directly measured data are available. keywords: modelling, runoff, mike, lowland catchments introduction water resources has become more and more important in the last decades in many regions of the world due to the increasing water demand of agriculture, industry and population and also due to climate change. the main difficulties with resources arisen from their great spatial and temporal variability. therefore sustainable water management require detailed and accurate information about the processes of the hydrological cycle (e.g. spatial and temporal variation of runoff, infiltration, soil moisture). the growing significance of this issue led to the development of hydrological models, since simulated results of hydrologic models are useful in water and land resource management (sahoo et al., 2006). hydrological models were developed for understanding and quantifying the factors of the complex hydrological cycle by mathematic, physical or empirical functions on a well-defined hydrological system or catchment. the components of the hydrological system (surface and subsurface waters, urban drainage or sewage systems) are in close connection and this system involves complex, incompletely understood interactions among flow, sediment transport and channel form (rodrigez et al., 2004). thus a well-designed hydrological modelling software should take into account these components (singh and frevert, 2001). hydrological models can be 1) conceptual: rough simplifications of reality, conceptualising the ideas of important processes and simulating internal variables or 2) physically based: processes are described by detailed physical equations. based on spatial resolution, they can be 1) lumped, representing the entire catchment by a few boxes and no spatial differentiations are considered, and “) distributed models dividing the catchment into a large number of cells (lundin et al., 2000). physically distributed hydrological models use parameters related directly to the physical characteristics of the watershed (e.g., distribution of topographic, geologic, soil and vegetation parameters) and spatial variability in both physical characteristics and meteorological conditions (sahoo et al., 2006). the applied mike she hydrological modelling software is a widely used physically distributed hydrologic model, suitable for modelling different components of a hydrological system e.g. rainfall–runoff (makungo et al., 2010; odiyo et al., 2012), evapotranspiration (vázquez and feyen, 2003), groundwater movement (demetriou and punthakey, 1999), rivers stage (panda et al., 2010), soil hydraulic properties (romano and palladino, 2002), or the complete hydrological system of a catchment (singh et al., 1999; liu et al., 2007; doummar et al., 2012). 50 právetz et al. (2015) on hydrologically extreme areas, such as the lowland small catchments of the carpathian basin, more accurate description and forecast of the water balance is a very important objective, since only a few exact data are available about evaporation, runoff, infiltration and water storage conditions of the area. the aim of the research was to model runoff and discharge for a ten year period on the fehértómajsa canal, a sub-catchment of the tisza river, in order to test the predictability of hydrological changes related to future climate change. modelled data were compared to ata-station measurement data in order to verify the modelling process. in the meantime the applicability and data demand of the mike environment was also assessed. study area the modelling was carried out on the catchment of the fehértó-majsa canal (se hungary), a 290 km 2 subcatchment of the tisza river. the canal has 9 tributary canals and canal density is 0.68 km/km 2 on the basis of the total length of canals managed by water directorate (fig. 1). the major part of the catchment (the western, upstream section) is located on the dorozsmai-majsai sand ridge, while the eastern, downstream section of the catchment is located on the south-tisza valley (dövényi 2010). low slope conditions exist on the catchment, despite the ridge-like character of the area. the slope of the major canal is 0.78-1.16 m/km on the upper reach and 0.27-0.78 m/km on the lower reach. the maximum relief of the major canal is 24.4 m. the vertical fragmentation of the catchment is relatively high compared to lowland landscapes (the relative relief is 3-6 m/ km2) due to the system of the residual ridges and blown-out depressions, arranged into northwest-southeast direction, defining also the main runoff direction of the major and tributary canals (marosi-somogyi 1990). the climate of the region is humid continental, facing drying in the past decades. based on meteorological data, this drying tendency means that the precipitation distribution was increasingly uneven, characterised by less frequent and decreased amount of summer precipitation. in the region of the studied catchment, the annual mean temperature and the average annual duration of sunshine is the highest in the country (pálfai, 1990), and the annual precipitation amount is quite low (520-570 mm), thus the climatic water stress is an important factor in this region (the average annual water scarcity is 520-570 mm –omsz 2001). the aridity of the region is enhanced by the unfavourable moisture regime of the dominantly sandy soils, because the water retention capacity of these soils is low. based on the climatic and physical geographical parameters the area faces with moderate inland excess water hazard and high drought hazard (fiala et al., 2014; mezősi et al., 2014). due to the regionally elevated situation of the upper-catchment, the groundwater regime is different on the lower-catchment (near to szatymaz), –where the average groundwater level is 115-155 cm below the surface – and on the uppercatchment (in the sand ridge area), where the average groundwater level is 200-300 cm below the surface (ativizig). data and methods the modelling of water balance on the fehértó-majsa canal was carried out by using a coupled mike she/mike 11 model. setting up the model requires the input of a number of data sets, explained in detail below. the modelling software from the wide range of mike software products, mike 11 and mike she were used. mike 11 is a one dimension (1d) river and channel modelling software, while mike fig. 1 location of the studied catchment modelling runoff on a small lowland catchment, hungarian great plains 51 she is 2d integrated catchment modelling software. the two modelling environments can be coupled, thus the interactions between the water flow and the catchment could also be interpreted. the mike 11 is an implicit finite difference model for computation of one dimensional unsteady flow with free surface. mike 11 applied with the fully dynamic descriptions solves the vertically integrated equations of conservation of volume and momentum (the ‘saint venant’ equations), based on the assumptions that the water is incompressible and homogeneous. the mike she is a deterministic, fully distributed and physically based modelling system for modelling the major processes of water flow in the land phase of the hydrological cycle, including a range of numerical methods for modelling each hydrological processes. each of these processes can be represented at different levels of spatial distribution and complexity, according to the goals of the modelling study and the availability of field data. the advantage of the mike she is the high integration of the elements of the hydrological process, in which the interrelations between these processes are counted. due to the modular approach implemented in the mike she, each of the hydrologic processes are calculated separately and integrated on the basis of the interrelations between these processes (graham and butts, 2005). the integration of different input data into the model land cover data to evaluate the effect of vegetation cover of the modelled catchment, 1:100.000 scale corine land cover (clc) database was applied. the parameters of the different land cover types has importance in modelling surface runoff, since land cover type define the runoff factor of the precipitation. on the analysed catchment, 17 different land cover types were identified, thus defining the parameters for each land cover type is important (fig. 2.). land cover affects overland flow and evapotranspiration component during modelling. the calculation of overland flow is based on the manning's roughness coefficient (chow 1959) in the mike software. the manning's roughness values for the clc land cover types are indicated in table 1. for calculating the evapotranspiration component mike she requires the leaf area index (lai) and the root zone depth for each land-use type. these values were defined based on the clc classes (table 1). soil data the soil data can be integrated into the model as polygon features. for the modelling the effect of soil on the, the parameters of the unsaturated soil are important (depth of the soil layer, water retention parameters, hydraulic conductivity). the parameters of the unsaturated soil zone were described for the model on the basis of the 1:100 000 scale agrotopographical map (agrotopographical database, 1991) (fig. 2). the water retention parameter of the soil can be defined by the pf curves of the different soil types to estimate the soil moisture balance. these pf curves were described by stefanovits et al. (2010) for the main soil texture classes (sand, loam, clay), thus the soils of the study area were categorised into these classes: 1. sand: blown sand, humic sandy soil, chernozem type sandy soil 2. loam: meadow chernozem, solonetzic meadow chernozem, meadow soil 3. clay: solonchak solonetz, meadow solonetz, solonetzic meadow soil table 1 parameters related to the corine land cover (clc) classes used in the model (zhao et al., 2012; chow, 1959) corine code type lai index root zone depth (m) roughness 112 discontinuous urban fabric 0 0 0.1 121 industrial or commercial units 0 0 0.1 131 mineral extraction sites 0.98 0.5 0.04 142 sport and leisure facilities 0.98 0.5 0.05 211 non-irrigated arable land 1.375 0.5 0.04 221 vineyards 1.5 1 0.05 222 fruit trees and berry plantations 1.5 1 0.05 231 pastures 1.76 0.5 0.035 242 complex cultivation 1.375 0.5 0.04 243 land principally occupied by agriculture, with significant areas of natural vegetation 1.375 0.5 0.05 311 broad-leaved forest 2.33 2 0.09 312 coniferous forest 2.45 2 0.09 313 mixed forest 2.53 2 0.09 321 natural grassland 1.76 0.5 0.035 324 transitional woodland shrub 1.97 1 0.07 411 inland marshes 1.82 0.5 0.07 512 water bodies 1.81 0 0 52 právetz et al. (2015) the hydraulic conductivity can be defined by several methods e.g. averjanov, van genuchten, campbell/burdin. important input parameters in the calculation of hydraulic conductivity are the saturated hydraulic conductivity (ksat), saturated soil water content (θsat), residual soil water content (θres) and empirical values of the inverse of the air entry value (α) and the shape parameters of the van genuchten (n). mike she needs these parameters to estimate the water content of unsaturated soil during the simulation, however the evaluation of these parameters are very complex, requiring extensive field and laboratory measurement, thus the catchment-scale evaluation is problematic. therefore the reference values, defined by cook (2012) for different soil texture types (table 2) were used in the modelling. topography the runoff directions throughout the catchment were evaluated using surface topographical data. the topography input data was obtained from a 5 m resolution digital elevation model (dem). the mike she re fig. 2 soil and land cover types on the studied catchment table 2 hydraulic parameters for soil texture types (cook, 2012) type θres θsat α, cm -1 n ksat ft/day sand 0.045 0.43 0.145 2.68 23.39 loamy sand 0.057 0.41 0.124 2.28 11.49 loam 0.078 0.43 0.036 1.56 0.82 silt loam 0.067 0.45 0.02 1.41 0.35 sandy clay loam 0.1 0.39 0.059 1.48 1.03 clay loam 0.095 0.41 0.019 1.31 0.2 silty clay loam 0.089 0.43 0.01 1.23 0.06 loam 0.078 0.43 0.036 1.56 0.82 sandy clay 0.1 0.38 0.027 1.23 0.09 silty clay 0.07 0.36 0.005 1.09 0.02 peat 0.1 0.7 0.05 1.1-1.3 0.05-1 modelling runoff on a small lowland catchment, hungarian great plains 53 quires a special raster dataset, a (.dsf2) grid point file. hence the original dem requires some transformation procedures. firstly, a point file was created using arcgis and the elevation data of the dem was linked for each point. the resulted point shape file can be used as input and a digital elevation model can be generated by interpolation in the model. water flows (canals) to evaluate the canal network and the features of the canals, a mike 11 model was developed. the canal network was implemented using polyline gis maps and cross-sectional and longitudinal section data were joined to the canals. the description of the canals was achieved through the specification of cross-sections of the canal. in defining the cross-section geometry, the maximum elevation is specified in such a way that the cross-section will accommodate the maximum expected water levels. the placed markers of the canal bank define the horizontal boundary of the hydraulic area. if, during a simulation, the water level rises above the maximum elevation in the processed data table, the hydraulic area is calculated by assuming the river banks extend vertically upward. this is not realistic, however the computation of the runoff is simpler, moreover the model cannot compute horizontal flooding as a 1d model. important parameter is the channel bed roughness (n), since it has an impact on the runoff velocity. the roughness factor is defined by the shape of the channel and the vegetation type and density. in this study, a uniform n value of 0.035 was used, which is consistent with values proposed by chow (1959) for streams with hydraulic characteristics similar to the studied canals. as boundary condition, prescribed infow and outfow points and initial boundary conditions also have to be defined. here, the inflow boundary conditions at the upstream end of the branch was closed end (q=0), since there is no inflow at the upstream end of the modelled canal. as the outflow boundary conditions at the downstream end of the branch stagedischarge relation or a simple water level (in meter above sea level). groundwater data to describe the effect of the saturated zone on the system relative groundwater depth data was used. the depth of the groundwater has effect on the runoff and water level of the canal in two ways: if the groundwater level is higher than the bottom of the canal, groundwater inflow represents additional water within the system; if the groundwater level is lower, water outflow from canal represents water loss within the system. the model processes the groundwater level changes over time, starting with a preliminary defined initial value. this value can be one value representing the whole catchment or an elevation model of the relative or absolute groundwater level. in this study elevation model was interpolated from the data of 6 groundwater wells (fig. 2) and this elevation model (fig. 3) was the input data for modelling. beside ground water data, properties affecting subsurface activities include saturated hydraulic conductivity of the saturated zone layers and special geologic properties of the soil profile (e.g. less permeable lens). the inclusion of geologic data is op fig. 3 initial relative groundwater depth on the study area (01.01.2003) 54 právetz et al. (2015) tional in the model. the subsurface system was defined by closed boundary condition in the model, thus the horizontal inflow and outflow is not allowed during the modelling. meteorological data to integrate the climatic conditions, mike she model requires three main inputs: precipitation rate air temperature and reference evapotranspiration. one of the most important meteorological input data of runoff models is the precipitation amount, since the precipitation is the main water input in the system. for the study area observed daily data of 4 meteorological stations was available in the simulated period (2003-2012). into the model, the average data of the 4 stations was calculated and this value was applied for the whole area. in the model, the precipitation can runoff, infiltrate or temporarily store in the soil. the storing capacity (mm) is an input parameter of the model and this value defines the thresholds of infiltration or runoff. the model is very sensitive to this parameter, significantly influencing the model results, thus preliminary testing is essential (frana, 2012). the infiltration and runoff are defined by the vegetation and roughness of the land cover and the parameters of the unsaturated soil zone. the physical state of the precipitation (rain, snow) is also important, thus the data series of temperature is also necessary for the simulated time period. temperature has influence on the model result because of the water storing in case of frost periods or the increased evapotranspiration in case of high temperatures. in the model, daily average temperature data was used. the most problematic meteorological parameter is the evapotranspiration. detailed catchment scale evapotranspiration data are not available for the study area, only large scale yearly average values. this yearly average could be used in the model by calculating daily values, however this constant value is not realistic due to the significant temperature variation during the year and this would resulted in large errors in the model result. to provide more accurate values for the model, the evapotranspiration data should be corrected with the daily temperature variation using the correction values. for this correction, data of fao (2015) was used. the modelling process after uploading the necessary data simulation was run for a 10-year period between 2003 and 2012. in all 9 model variations were generated. the first is termed as the initial model, containing the data in the form detailed above. since from among the input datasets soil parameters can be attributed with the greatest uncertainty as a consequence of their relatively poor resolution (1:100 000) and the lack of measured data concerning physical properties, in the following variations the sensitivity of the model to the variation of these were tested. primarily, parameters related to hydraulic conductivity and storage capacity, influencing infiltration and ground water flow were changed by considering possible minimum and maximum values concerning loamy soils. in all 9 different model variations were set up (table 3). in the first two variations specific s torage was increased and decreased by 50%, in the follo wing two variations specific yield was modified similarly. in case of model variation no. 6 and 7 hydraulic conductivity was increased and decreased by an order of magnitude. subsequently, the detentio n storage parameter was increased to 2 and 5 mm. co ncerning the final variation the calculation method of the water retention parameter was modified and instead of soil pf curves the van genuchten formula was applied with empirical values for α and n (cook, 2012). all model variations were run and discrepancies between the simulated and the measured di scharges were analysed. model variations were validated against discharge data recorded near the outlet of the catchment at the szatymaz gauge station. the station records the discharge of the canal daily at 7:00 am since the 1990s, therefore simulated discharge data were retrieved from the model also for this time of the day. for comparisons the differences (in m 3 /s and %) between calculated and the measured daily data were averaged for the entire period, and also on a yearly and a monthly base. the agreement between modelled and measured data was also analysed by calculating correlation coefficients. table 3 modified input parameters in the different model variations model variations specific storage (1/m) specific yield hydraulic conductivity (m/s) detention storage (mm) retention curve initial 0.2 0.2 2.8e-005 0 pf curve 1. 0.3 0.2 2.8e-005 0 pf curve 2. 0.1 0.2 2.8e-005 0 pf curve 3. 0.2 0.3 2.8e-005 0 pf curve 4. 0.2 0.1 2.8e-005 0 pf curve 5. 0.2 0.2 2.8e-006 0 pf curve 6. 0.2 0.2 2.8e-004 0 pf curve 7. 0.2 0.2 2.8e-005 2 pf curve 8. 0.2 0.2 2.8e-005 5 pf curve 9. 0.2 0.2 2.8e-005 0 van genuchten modelling runoff on a small lowland catchment, hungarian great plains 55 data were also compared in terms of dry (low water) and humid (high water) periods. the distinction was made by calculating the mean of the measured data series (0.208 m 3 /s). consequently, values below and above this value were considered as low water and high water data. results concerning the initial model the average discrepancy of the simulated data for the whole period (2003 2012) was +0.027 m 3 /s, meaning a 12% overestimation of the measured discharge (table 4). the simulated data of the initial model were in a good agreement with the measured data in low flow periods. on the other hand in more humid periods the model overestimated runoff and simulated peak discharges were in delay to the measured data (fig. 4). the maximum difference experienced in the daily data series was 2.5 m 3 /s and occurred during the 2006 excess water period. the correlation coefficient between the daily data of the simulated and modelled series was e xtremely poor as a consequence of overestimation and time lags between the two datasets. naturally, if monthly and annual means are compared the results improve. on a monthly and annual basis the value of r 2 is 0.51 and 0.94 (table 4). concerning the entire modelling period the lo west differences were experienced in case of the initial model and in case of model variation no. 3 and 4 (discrepancy: +0.026-0.027 m 3 /s and 12-13%), where the specific yield parameter was modified. the highest discrepancy was found in case of model variation 8, run with a 5 mm detention storage value (discrepancy: +0.314 m 3 /s and 502%). each of the modified model variations overestimated runoff during low flow periods. the fitting of the modelled data series to the control data was varying. based on the tests, the modification of the specific yield parameter hardly caused any change in the results compared to the initial model (table 4). in these variations the overestimation was 43%, being only 0.07-0.08 m 3 /s, which is reasonable if we consider that during low flow mean discharge is only 0.128 m 3 /s. greater differences were seen when changing the values of the specific storage parameter. nevertheless, the largest discrepancy was experienced in case of model variation no. 5 and 8, when hydraulic conductivity was considerably decreased and detention storage was increased. in these cases modelled discharges were in averages 5 times higher than the control values (table 4). when hydraulic conductivity was increased in model variation no. 6, low water values were still considerably higher than in case of the initial model, probably as a result of increased ground water yield to canals. concerning high flows both underestimation and overestimation occurred in comparison to the measured data series. best correspondence was experienced in case of the initial model (-0.115 m 3 /s, -17%), and model variation no. 7 (+0.103 m 3 /s, +15%). tests showed that high flow results are again hardly sensitive to changes in the specific yield parameter just like in the case of low flow data (table 4). when specific storage is modified more considerable deviations occur. in model variation no. 5 and 6 the modification of table 4 mean absolute and relative deviation of models compared to the measured data. the best three results are highlighted by bold letters low water period high water period complete period r 2 monthly mean values r 2 annual mean values model variations mean absolute difference (m 3 /s) mean relative difference (%) mean discharge (m 3 /s) mean absolute difference (m 3 /s) mean relative difference (%) mean discharge (m 3 /s) mean absolute difference (m 3 /s) mean relative difference (%) mean discharge (m 3 /s) initial +0.075 +43 0.128 -0.115 -17 0.547 0.027 +12 0.235 0.51 0.94 1. +0.094 +80 0.146 -0.157 -23 0.506 0.031 +15 0.238 0.48 0.78 2. +0.136 +160 0.188 +0.186 +28 0.848 0.148 +71 0.356 0.31 0.89 3. +0.075 +43 0.127 -0.121 -18 0.542 0.026 +13 0.233 0.51 0.94 4. +0.076 +45 0.128 -0.119 -18 0.543 0.026 +13 0.234 0.51 0.93 5. +0.311 +496 0.363 +0.327 +49 0.991 0.315 +152 0.523 0.14 0.41 6. +0.202 +287 0.253 -0.264 -39 0.399 0.083 +39 0.291 0.63 0.54 7. +0.148 +184 0.199 +0.103 +15 0.766 0.136 +65 0.344 0.28 0.82 8. +0.314 +502 0.366 +0.358 +53 1.021 0.325 +156 0.533 0.11 0.41 9. +0.205 +293 0.257 -0.128 -19 0.535 0.119 +57 0.328 0.17 0.39 56 právetz et al. (2015) fig. 4 simulated discharge (m3/s) curves of the different model variations compared to the measured data series modelling runoff on a small lowland catchment, hungarian great plains 57 hydraulic conductivity resulted high deviations, the model seems to be sensitive to this parameter. it is also obvious that changing the value of detention storage the outcome of the model at high flows can be greatly affected. in case of periods with higher precipitation the use of the van genuchten method instead of the pf will not make a significant difference if average deviations are considered (table 4). correlation coefficients calculated by plotting against modelled and measured data show that a daily based precise prediction of discharge data is not possible at the present state of the model. in terms of monthly means the highest r 2 (0.63) was received in case of model variation no. 6, with a low hydraulic conductivity (table 4). however, as it was seen earlier this variation resulted high deviations in both low water and high water periods, therefore, the relatively high correlation in monthly data is rather the result of an averaging effect of positive and negative deviations. the second highest correlation (0.51) was experienced in case of the initial model and model variations no. 3 and 4, reinforcing previous results (fig. 5a). the lowest correlation coefficient (0.11) was received for model variation no. 8 which is in harmony with expectations based on absolute and relative deviations. fig. 5 correlation of modelled and control data on a monthly (a) and on an annual (b) base in case of the initial model variation the values of r 2 naturally improve if annual means are considered. in this case coefficients were as high as 0.94 in terms of the initial model and model variation no. 4 (table 4). this means that predictions can have a high accuracy on a yearly basis (fig. 5b). coefficients above 0.80 were received for model variations no. 2, 4 and 7. thus, at an annual resolution most of the model variations are well applicable. another key issue of the model is the time lag between measured and modelled peak discharges. this can explain the relatively low r 2 values in terms of monthly values. in case of the 2010 high flow period the first peak of the flooding was missed by most of the model variations, and only those showed some overlay, which anyway performed poor during the deviation and correlation analysis. nevertheless, the second wave was captured well by the initial model and those variations where specific yield and specific storage were modified (fig. 4). the overlap with the following 2-3 peaks is variable, and in certain cases fake peaks also appear in the modelled data series. the situation in terms of the 2006 peak is even more interesting, as in this case actually none of the models captured the flood wave and increasing discharge values appeared with a several month delay (fig. 4). this phenomenon might be explained by human interventions on the catchment, namely in this period there was an extensive inland excess water cover on agricultural areas, which was managed by draining and pumping the water directly into the main canal. as exact data on the amount of the drained water was not available, this effect could not be integrated to the model. similar issues may affect the time lags experienced in terms of the 2010 flood period. conclusions after performing several runs with modified soil parameters we found that the initial model, comprising average values advised by the literature and values retrieved from low spatial resolution data, proved to be relatively accurate in predicting monthly and annual discharges. the model is not sensitive in general to the modification of the specific yield parameter and slightly sensitive to the modification of the specific storage parameter. much higher deviations were experienced as a matter of changing hydraulic conductivity and detention storage. concerning low flow periods in relative terms a significant overestimation was experienced, and not any of the model variations could improve deviations. the modification of sensitive parameters listed above caused dramatic changes in the results and ruined comparability to the control data. as most of the modelled period is comprised of low flow events, the field assessment of the above listed parameters, especially hydraulic conductivity would be crucial in the future to improve the output of the model. in terms of high flows relative differences between modelled and control data are lower. best performing models underestimate discharge, which can be significantly improved by modifying the detention storage parameter. consequently, in the future dry (low flow) and wet (high flow) periods of the model should be fine tuned by adjusting different parameters. 58 právetz et al. (2015) the overall validation of the model is significantly hindered by the observed time lags between measured and modelled peak discharges. this problem is partly caused by artificial draining activity on the catchment, especially during the spring period. the issue could be overcome, and correlation between measured and modelled data could be increased if measured or calculated data of draining were introduced to the model. as far as the above measurements and estimations are not completed and integrated to the calculations, the model is rather applicable to predict monthly and annual runoff and discharge. nevertheless in terms of a lowland catchment with such a low relief this can still provide valuable data for water management. moreover, applying the above introduced methodology and input data the runoff on other small catchments in the lower tisza region could also be modelled. the initial model variation at its present stage can also be applied to predict general changes in runoff related to climate change. based on the performance of the present model, if the simulation data of regional climate models are applied annual changes can supposedly be predicted at a high accuracy. acknowledgements this research was supported by the ipa cross-border cooperation programme of the european union under the project wahastrat (husrb/1203/121/130), by the otka 100761 research found and the bolyai jános research scholarship of the hungarian academy of sciences. references agrotopographical database, 1991. agrotopographical database, budapest, available at: http://maps.rissac.hu/agrotopo/ chow, v.t., 1959. open-channel hydraulics: new york, mcgrawhill book co. cook, a. 2012. development of an integrated surface and subsurface model of everglades national park. fiu electronic theses and dissertations, florida demetriou, c., punthakey, j.f. 1999. evaluating sustainable groundwater management options using the mike she integrated hydrogeological modelling package. environmental modelling & software 14, 129–140. doi: 10.1016/s1364-8152(98)00064-4 doummar, j., sauter m., geyer, t. 2012. simulation of flow processes in a large scale karst system with an integrated catchment model (mike she) – identification of relevant parameters influencing spring discharge. journal of hydrology 426–427, 112–123. doi: 10.1016/j.jhydrol.2012.01.021 dövényi, z. 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solution to treat mixed-type human datasets from socio-ecological systems lisa b. clark1, eduardo gonzález1,2*, annie l. henry1, anna a. sher1* 1department of biological sciences, university of denver, denver, co, 80208-9010 2department of biology, colorado state university, fort collins, co, 80523 *corresponding author, e-mail: edusargas@hotmail.com research article, received 26 august 2020, accepted 8 december 2020 abstract coupled human and natural systems (chans) are frequently represented by large datasets with varied data including continuous, ordinal, and categorical variables. conventional multivariate analyses cannot handle these mixed data types. in this paper, our goal was to show how a clustering method that has not before been applied to understanding the human dimension of chans: a gower dissimilarity matrix with partitioning around medoids (pam) can be used to treat mixed-type human datasets. a case study of land managers responsible for invasive plant control projects across rivers of the southwestern u.s. was used to characterize managers’ backgrounds and decisions, and project properties through clustering. results showed that managers could be classified as “federal multitaskers” or as “educated specialists”. decisions were characterized by being either “quick and active” or “thorough and careful”. project goals were either comprehensive with ecological goals or more limited in scope. this study shows that clustering with gower and pam can simplify the complex human dimension of this system, demonstrating the utility of this approach for systems frequently composed of mixed-type data such as chans. this clustering approach can be used to direct scientific recommendations towards homogeneous groups of managers and project types. keywords: gower’s similarity coefficient, partition around medoids clustering, human dimension, coupled human and natural systems, land management introduction the human dimension of biological conservation, ecological restoration, and environmental management in a broad sense is a recent, growing focus in the scientific literature as an important component of coupled human and natural systems (chans, a.k.a. socio-ecological systems, liu et al., 2007). when considering human systems, both within and separate from chans, large datasets are often involved due to the complex and varied nature of survey data. the chans framework can also yield data that are challenging to work with due to the interconnections between systems and data that encompasses multiple scales. multivariate analyses are therefore frequently used, however survey and ecological data often include mixed types of variables (i.e., continuous, ordinal, and categorical), which cannot be treated by most conventional multivariate tests. for example, while cluster analyses are commonly used in social sciences, most use well known distance metrics such as euclidean (e.g., garcía-llorente et al., 2011) or bray curtis (e.g., higuera et al., 2013), which cannot handle mixed data. gower dissimilarity matrices with clustering using partitioning around medoids (pam) have been used recently as a new solution to the problem of mixed data in other disciplines, such as biomedical sciences, ecology, and socioeconomics (table 1), but never in chans before now. the gower similarity coefficient is specifically designed to deal with mixed data, which becomes even more likely when combining human and natural variables as found in chans. gower also has additional advantages such as allowing for missing values and for different weights to be assigned to each variable (gower, 1971; legendre and legendre, 2012). pam is an alternative for the popular, non-hierarchical k-means method. unlike those methods, pam accepts other distance metrics besides euclidean and is useful for relatively small sample sizes with outliers (borcard et al., 2011; kaufman and rousseeuw, 1990). this study illustrates the use of gower distances with pam to investigate the human dimension of coupled systems in a case study of managers involved in the control of an invasive tree (tamarix spp.) in the riparian southwestern u.s. of specific interest was whether there were profiles of managers or projects (based on their education, management role, experience, etc.) that were associated with particular management decisions. more generally, this study examines how characteristics and decisions of this population of managers and their projects could be more easily described through clustering. while many restoration ecology studies have inventoried management actions in river restoration projects (bernhardt et al., 2007; morandi et al., 2014), to the authors’ knowledge, an in-depth, quantitative exploration of the characteristics of managers and their projects has not been done (except see sher et al., 2020). previous literature on the human dimension of mailto:edusargas@hotmail.com 52 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. restoration ecology has only focused on one aspect of decision-making such as partnerships or political input (e.g., kallis et al., 2009; oppenheimer et al., 2015), despite the myriad of aspects that may be important, including education level, governing organization, and collaboration. it was hypothesized that the proposed statistical method would give interpretable, meaningful clusters of managers, types of projects, and types of management decisions. we then tested the hypothesis that management decisions could be predicted by characteristics of managers and/or projects. this is important because if managers with particular characteristics are consistently making specific management decisions such as choosing to monitor their projects, then scientific recommendations regarding those decisions can be more accurately targeted toward the relevant managers. we believe that this novel application of gower distances with pam will be useful to within any field that may study the natural-human interface with mixedtype data sets, including not only restoration ecology but also human geography, environmental sociology, and environmental psychology. methods case study tamarix spp. (tamarisk, saltcedar) is a shrubby tree native to eurasia that can grow in monocultures along riverways and impacts wildlife habitat (bateman et al., 2013; sogge et al., 2013; strudley and dalin, 2013), soil salinity (ohrtman and lair, 2013), and native plant communities (friedman et al., 2005; merritt and poff, 2010). tamarix is one of the most pervasive invasive riparian plants across the southwest u.s. and has also invaded other arid and semi-arid world regions such as mexico, argentina, australia and south africa (sher, 2013). removal of tamarix is a common practice in river management (gonzález et al., 2015), and there are many methods managers use to remove this species, including a broadly-dispersed biological control (bean and dudley, 2018). these projects are conducted on lands owned by a variety of agencies including federal (e.g., bureau of reclamation), state (e.g., state natural resource departments), local (e.g., conservancy districts), non-profit (e.g., the nature conservancy), and private (e.g., individual landowners). in order to investigate the human dimension of the restoration of tamarix-dominated lands, land managers of tamarix removal projects were identified from a large dataset originally collected to assess the effects of removal method on vegetation (fig. 1; see gonzález et al., 2017). this was a collaborative effort of 16 research institutions; sites included all locations across the southwestern u.s. where data were available, distributed across the upper colorado, lower colorado, and middle rio grande river basins. these managers were invited to participate in an online survey and in-person interviews in order to assess whether management decisions in these projects were associated with individual characteristics of those managers or projects. information about the managers’ backgrounds was needed, as well as the approach to restoration specific to each of their projects. the online survey was administered through qualtrics to land managers. the 20-minute survey was tested through multiple iterations using mock interviews and through qualtrics by trusted land managers and collaborators to ensure clarity. fig. 1 map of study area. ucrb – upper colorado river basin; lcrb – lower colorado river basin; rgrb – rio grande river basin. points are tamarix removal project sites table 1 examples of papers using gower similarity coefficients with partitioning around medoids (pam) cluste ring to treat mixed data types. field examples biomedical science han et al. 2014, canul-reich et al. 2015, hummel et al. 2017 genetics krichen et al. 2008, stefani et al. 2014 marketing/analytics silva et al. 2016, lismont et al. 2017, arunachalam and kumar 2018 sports research akhanli and hennig 2017 ecology williams et al. 2011, pimenta et al. 2017 socioeconomics kühne et al. 2010, gellynck et al. 2011, hennig and liao 2013, iparraguirre et al. 2013, maione et al. 2018 sociology bohensky et al. 2016, king et al. 2016 this selection was obtained from a search in google scholar using the chain “gower and partitioning around medoids” done on mar 21, 2018 that yielded 410 results. the list is not exhaustive. clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. 53 the survey was approved by the university of denver institutional review board (#816375 -5), and it was fielded from august 2016 to march 2017 (clark et al., 2019) . we contacted 46 managers via email or phone; only one manager who was contacted did not complete the survey, thus our final sample size was 45 managers. the subsequent survey results encompassed 78 projects including 227 sites where tamarix was treated (93% of treated sites originally sampled for vegetation data reported by gonzález et al., 2017a; 2017b). see table 2 for diversity of respondents. seventeen managers had more than one project and 54 projects had multiple managers. some of the variables were r elated to each manager, and others to specific projects. thus, the data were considered in terms of managers (n=45) and projects (n=78). as this study represents nearly all tamarix removal projects in the southwestern u.s. over the last 20 years, our sampl e size can be considered highly representative of this population. the survey results produced continuous, ordinal, and categorical variables, organized into two general categories: characteristics and decisions (table 3). within each of these, some variab les were specific to projects, while others were specific to managers regardless of the project, such as education level. the characteristics variables included: governing agency or organization (“agency”; table 3), education, experience level, and management role. agency was considered both in relation to the manager and to the project, as it often differed. experience was also considered for the manager as an overall measure of management experience and for the project as a measure of location-specific experience. the decision variables covered the manager’s goals for each project, degree of collaboration across agencies, information sources, tamarix removal method, and monitoring methods. for information sources, managers were asked to rate the influence of information provided by particular agencies or organizations (e.g., formal: scientific articles; informal: peer conversations) on their decision-making, resulting in a count of the number of influential sources rated “somewhat influential” or higher. in the survey, managers also selected monitoring frequency for each type of monitoring method (e.g., physical, chemical, biological) but because most managers used more than one type and we were interested in how frequently any type of monitoring was done rather than each type, we created an ordinal variable for overall monitoring frequency where the highest frequency for any method was recorded. cluster analysis four cluster analyses were run for each of the variable categories – manager characteristics, project-specific characteristics, general management decisions, and project-specific management decisions – using partitioning around medoids (pam method; borcard et al., 2011; kaufman and rousseeuw, 1990) on a gower dissimilarity matrix (gower, 1971; legendre and legendre, 2012). the weighting of each set of variables was adjusted for each cluster analysis to give equal table 2 summary of respondent characteristics characteristic proportion of each category gender men 47% | women 53% education level high school 4% | bachelors 33% | masters 47% | doctorate 18% experience level < 11 years 24% | 11-20 years 22% | > 20 years 42% | did not identify as a land manager 9% owning agencies federal 49% | state 18% | local 12% | private/non-profit 14% | more than one agency 8% federal includes: national park service, bureau of land management, us fish and wildlife service, bureau of reclamation state includes: 1 state park service, 2 state natural resource departments, 3 state fish and wildlife services local includes: 3 municipalities, 1 tribe, 1 conservation district private/non-profit includes: 1 non-profit, 1 private company, 1 university, individuals managing agencies federal 29% | state 12% | local 9% | private/non-profit 14% | more than one agency 36% federal includes: national park service, bureau of land management, us fish and wildlife service, bureau of reclamation state includes: 1 state natural resource department, 1 state fish and wildlife service, 1 conservancy district local includes: 2 municipalities, 1 tribe private/non-profit includes: 1 non-profit, 1 private company, individuals employing agencies federal 47% | state 11% | local 16% | non-profit 20% | private 4% federal includes: national park service, bureau of land management, us fish and wildlife service, bureau of reclamation, us army corps of engineers state includes: 4 state natural resource departments local includes: 2 municipalities, 1 county, 2 conservation districts non-profit includes: 3 non-profits, 1 private company, 1 university percentages are calculated based on the total number of managers (for gender, education, experience, and employing agency) or projects (for owning and managing agency). 54 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. weight to each variable as the number of sub-variables was not consistent. however, for the project-specific management decisions, the goals of “none”, “other”, and “livestock forage” were only rarely selected in the surveys and drove the clustering in preliminary analyses, so were given a lower weight than the other goals. all clustering methodologies assign observations to the same cluster based on algorithms that consider the distance (or similarity) between observations. the clustering algorithm used by the pam method is an extension of the popular k-means algorithm, which uses euclidean distances only and therefore cannot deal with categorical data. unlike k-means, the pam algorithm can be fed with a dissimilarity matrix, a matrix that contains all pairwise distances between the observations, instead of the raw data. this broadens the choice of distance measures to others that allow continuous as well as ordinal and categorical variables. the pam algorithm computes k representative observations, called medoids, through an iterative process that ends when the average dissimilarity of the medoids to all the observations in the cluster is the minimal possible. as in k-means, the number of clusters (k) has to be defined a priori. we used the optimum average silhouette width (asw) method to estimate the best number of clusters (kaufman and rousseeuw, 1990). in this study, the number of cluster groups was based on the highest average silhouette width that had a feasible logical interpretation, determined by significant differences on the survey variables between cluster groups using chi-square or mann-whitney u comparisons for each variable. the dissimilarity matrix that was used to feed the pam procedure was computed using the gower similarity coefficient (gower, 1971; legendre and legendre, 2012). the gower metric has other advantages besides allowing mixed data (i.e., data that includes continuous, ordinal, and categorical variables). first, all variables including ordinal and categorical are scaled to [0,1] so the requirement of the pam method of all variables being dimensionally homogeneous (borcard et al., 2011) is met. normality for continuous variables is not required. second, missing values are discarded from the calculation without the need of removing the observation or the variable; so the dataset can include missing values and no power is lost. third, it is possible to set different table 3 twenty-four survey variables used for analysis, by cluster category: characteristics vs. decisions for managers and for specific projects. category variable type variable description m a n a g e r c h a ra c te ri st ic s continuous management role number of roles out of: directly make decisions, implement decisions made by others, oversee projects with input from a partnership, collect data, other ordinal overall experience <11 years, 11-20 years, >20 years ordinal education high school, bachelors, masters, phd categorical employing agency private, non-profit, local, state, federal p ro je c tsp e c if ic c h a ra c . ordinal experience in project area <11 years, 11-20 years, >20 years categorical managing agency of proj. private/non-profit, local, state, federal, collaborative categorical owning agency of project private/non-profit, local, state, federal, collaborative m a n a g e m e n t d e c is io n s categorical type of inform. sources formal (e.g., peer-reviewed literature, conference talks), informal (e.g., conversations, past experience), mixed continuous number of information sources continuous number of monitoring methods includes visual, biological, physical, and chemical ordinal frequency of monitoring variable or <every 4 yrs, every 1-2 yrs, >annual continuous number of monitoring groups includes self, other personnel within agency, collaborators, university scientists, private consultants, other continuous number of collaborating groups includes federal personnel, state personnel, private consultants, scientists, neighbors/peers, other continuous number of collab. scientist groups includes federal, state, county, private consultants, non-profit agency, university, other continuous number of researching groups includes self, university scientists, other scientists continuous removal method (four variables) proportion of sites with each method (biocontrol only, cut-stump, heavy machinery, and burning) by manager p ro je c tsp e c if ic d e c is io n s categorical goals (14 variables) yes/no for each of 14 goals within the following categories: plant, wildlife, water, people, other continuous removal method (four variables) proportion of sites with each method (biocontrol only, cut-stump, heavy machinery, and burning) within a project clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. 55 weights for each variable. in our case study, we assigned weights to the variables so that each set of variables (i.e., collaboration, role, etc.) was e qual in weight. all continuous variables were scaled before calculating the gower coefficients. the gower’s similarity coefficient between two observations (s ij) is calculated following the equation: 𝑆𝑖𝑗 = ∑ 𝑊𝑖𝑗𝑘 𝑆𝑖𝑗𝑘 𝑝 𝑘=1 ∑ 𝑊𝑖𝑗𝑘 𝑝 𝑘=1 (1), where sij denotes the similarity of observations i and j for the kth variable, and wij is the weight given to the kth variable (a weight of 0 is given in case of missing values for i or j). the similarity s ijk is defined for continuous and ordinal variables as 1 −|𝑥𝑖𝑘 − 𝑥𝑗𝑘 | / 𝑟 (2), where r is the range of the variable. for categorical variables, sijk is defined as 0 if xik and xjk differ and 1 if xik and xjk are the same. the gower’s dissimilarity matrix is computed by transforming the similarities of all pairs of observations as √(1 − 𝑠𝑖𝑗 ) (3). the gower coefficients were calculated using the function daisy of the package cluster (maechler et al. 2018) and the pam clustering were run using the function pamk of the package fpc (hennig, 2013) in r 3.4.1 (r core team, 2017). cluster assessment in order to define the profiles of the resulting cluster groups, the mean response to each of the variables used to run the cluster analysis for each of the four cluster group pairs were compared pearson’s chi-square tests, for categorical data, or mann-whitney u, for continuous data, in jmp 13.0.0 (sas institute, 2014). mann-whitney is a non-parametric test, selected because our continuous variables were rarely normally distributed. to determine if the “characteristic” cluster groups (both for managers and for projects) helped explain “decisions” variables, the same app roach was used with characteristic clusters as the independent variable and individual decisions variables as the dependent variables. to account for the increased risk of a type i error due to the large number of tests, a bonferroni adjustment was applied to the alpha based on the number of analyses for each sub-question. results and discussion in this case study, gower similarity coefficients and pam clustering was used to summarize survey data comprised of mixed variable types in a coupled human and natural system. this approach created four clear sets of clusters relating to manager characteristics, project characteristics, management decisions, and project-specific decisions based on survey responses by managers of invasive tamarix removal projects. surprisingly, the characteristic clusters did not, for the most part, explain management decisions, suggesting that individual managers did not make choices based on their background, but instead that these decisions may be more the product of the agency or collaborative group and determined by their resources and/or priorities (sher et al., 2020). these results demonstrate the utility of this analysis approach and provide insight into the structure of this specific system, which can assist understanding of and thus communication with managers. previous research that has included surveys of managers has rarely investigated the linkage between managers backgrounds and management actions taken as determined by combinations of factors (but see sher et al., 2020). more often, surveys of approaches (bernhardt et al., 2007; morandi et al., 2014) or attitudes of managers has been assessed (e.g., curtis and de lacy, 1998, padgett and imani, 1999), typically with very little if any quantitative hypothesis testing (but see clark et al., 2019). at least one such study has implemented a multivariate clustering method for identifying opinions and attitudes of land managers toward implementing conservation initiatives (knight et al., 2010), but no subsequent analysis appears t o have been done with these clusters. in another, background was linked to management approach, but these traits were only considered singly, rather than contributing to a multi-dimensional profile (raymond and brown, 2011). it is our hope that this method of using gower similarity coefficients and pam clustering can help facilitate more studies of the hypothesized causal relationships between elements, as was done here. cluster results for each of the four variable groups, distinct pairs were created by the cluster analysis (table 4-7). coefficients are either mann-whitney u (continuous variables) or pearson’s chi-square (ordinal and categorical variables) and indicate significant differences between the cluster groups if bolded (p < 0.05). the manager characteristics cluster groups were explained primarily by employing agency, education, and management role, with an equal number of managers in each group (table 4). managers in group 1 (“federal multitaskers”) had lower education, worked for mostly federal agencies, and had more management roles including overseeing projects with input from a partnership, relative to group 2 (“educated specialists”). projects were distinguished by all of the variables used in the analysis: local experience, managing agency, and owning agency (table 5). most projects in the first group were characterized by having more locallyexperienced managers and tending to be owned and managed by larger or collaborative entities (“public”) whereas group 2 projects (“private”) were owned and 56 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. managed mostly by smaller organizations such as private companies or non-profits. there were two groups from the general management decision cluster analysis; these were significantly distinguished by information sources, monitoring, and the use of heavy machinery to remove tamarix (table 6). the first group (“quick and active”) used fewer sources of information but those sources were a mix of formal and informal; they used less comprehensive but more frequent monitoring and more heavy machinery than the other group (“thorough and careful”). the project-specific management decisions (table 7) were characterized by the selection of goals related to ecosystem health such as native plant diversity or habitat improvement and more removal by burning (group 1: “ecocentric”) while group 2 (“limited scope”) had few goals selected but did select “none” or “other” (e.g., community involvement, water conservation, research) goals more often and had more removal by heavy machinery. these groupings provided an overview of the managers involved in tamarix removal projects and the decisions they make, helping us understand which traits or aspects of projects are likely to be aligned. this clustering tool also facilitated the analysis of relationships between variables. numbers in table 8 are the coefficients from either mann-whitney u or pearson’s chi-square tests depending on the type of variable. no significant relationships were found with bonferroni adjusted 𝛂=0.004 and 𝛂=0.003 for general and project-specific decisions, respectively. counter to predictions, no strong relationships between manager characteristics and decisions made about projects (as shown by non-significant pairwise comparisons with individual variables; table 8a) were found (e.g., hagger et al., 2017; martin-lopez et al., 2007; roche et al., 2015). this result suggests that either managers exhibit no bias in decision making in these restoration projects based on their own backgrounds, and/or that there are enough other controls in place through mechanisms to overwhelm any such bias (clark et al., 2019, sher et al., 2020). these controls are likely to include the constraints and goals of specific agencies, the influence of collaborators, and the availability of resources for a given project. it is also possible that any influence of manager characteristics on decisions were too small to be detected by a sample of this size. similarly, whether projects were “public” or “private” did not strongly predict management decisions made about those projects, although private projects were more likely to have the listed goals, especially aesthetics and native plant diversity, than public projects (table 8b). public projects were more likely to have used biological control, but these results were not statistically table 4 description of cluster groups created from manager characteristics (asw=0.22), group 1: federal multitaskers (n=22), group 2: educated specialists (n=23) variable weight group 1 group 2 coefficient p role direct management role 0.05 64% 65% 0.11 0.92 implement decisions made by others 0.05 36% 9% 3.38 0.07 oversee projects with input from a partnership 0.05 86% 39% 11.62 <0.001 collect data 0.05 50% 26% 2.83 0.09 median breadth of management roles (0-4) 0.05 3 1 8.52 0.004 experience most common experience level 0.25 >20 years 11-20 years 5.92 0.12 education most common education level 0.25 bachelors masters 18.20 <0.001 agency most common employing agency 0.25 federal non-profit/ university 19.21 <0.001 table 5 description of cluster groups created from project-specific characteristics (asw=0.51), group 1: public (n=49), group 2: private (n=25) variable weight group 1 group 2 coefficient p experience most common local experience level 0.33 11-20 years <11 years 8.84 0.01 managing agency most common managing agency 0.33 collaborative private/non-profit 63.28 <0.001 owning agency most common owning agency 0.33 federal private/non-profit /university 53.87 <0.001 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. 57 table 6 description of cluster groups created from general management decisions (asw=0.18), group 1: quick and active (n=24), group 2: thorough and careful (n=20) variable weight group 1 group 2 coefficient p information source most common type of information sources 0.125 mix formal 15.40 <0.001 median breadth of information sources (0-22) 0.125 13 21 7.82 0.005 monitoring median breadth of monitoring methods (0-4) 0.125 2 3 10.11 0.002 most common monitoring frequency 0.125 > once a year > once a year or < every 4 years 8.09 0.04 collaboration median breadth of monitoring groups (0-6) 0.0625 2 3 2.54 0.11 median breadth of collaborating groups (0-7) 0.0625 3 2.5 0.10 0.75 median breadth of science collaborators (1-7) 0.0625 4 4.5 0.78 0.38 median breadth of researching groups (0-4) 0.0625 2 1 1.40 0.24 removal method mean proportion of biocontrol only 0.0625 0.18 0.05 2.98 0.08 mean proportion of cut-stump 0.0625 0.18 0.28 3.42 0.06 mean proportion of heavy machinery 0.0625 0.39 0.09 4.07 0.04 mean proportion of burning 0.0625 0.16 0.19 0.42 0.52 table 7 description of cluster groups created from project-specific decisions (asw=0.34), group 1: ecocentric (n=43), group 2: limited scope (n=29) variable weight group 1 group 2 coefficient p plant-related goals native plant diversity 0.0606 93% 28% 33.37 <0.001 ecosystem resilience 0.0606 79% 7% 36.09 <0.001 exotic plant removal 0.0606 95% 76% 6.01 0.01 wildlife-related goals habitat improvement 0.0909 100% 31% 41.06 <0.001 endangered species 0.0909 65% 0% 30.90 <0.001 water-related goals channel maintenance 0.0606 21% 14% 0.60 0.44 restore over-bank flooding 0.0606 60% 17% 13.20 <0.001 water quality 0.0606 28% 3% 7.00 0.008 people-related goals aesthetics 0.0606 40% 38% 0.02 0.89 recreation 0.0606 28% 34% 0.35 0.55 wildfire mitigation 0.0606 63% 21% 12.37 <0.001 other goals livestock forage 0.0303 9% 0% 2.86 0.09 other 0.0303 2% 28% 10.10 0.002 none 0.0303 0% 14% 6.28 0.01 removal method mean proportion of biocontrol only 0.0455 0.09 0.14 0.04 0.85 mean proportion of cut-stump 0.0455 0.22 0.33 0.53 0.47 mean proportion of heavy machinery 0.0455 0.23 0.33 6.48 0.01 mean proportion of burning 0.0455 0.25 0.11 4.57 0.03 58 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. significant with an adjusted alpha of p<0.003. however, it should be noted that as this study sample represented a near-census of tamarix projects in the southwestern u.s., such descriptive statistics may still be meaningful. projects that were owned and managed privately or by non-profits may have had the flexibility to have more specific and customized goals than those projects that required buy-in from larger or more diverse stakeholders. taken together, this information can inform future collaborations with managers and scientists in this coupled system by giving context to their interactions. for example, managers who are federal multitaskers may not have the capacity to try new methods but educated specialists may be more willing and able to do so. thus, educated specialists may be the best candidates to try innovative new practices and could be more directly targeted in communications and dissemination. additionally, increased understanding of managers by scientists is essential for building trust in relationships with managers, which is crucial to the success of any collaboration (vangen and huxham, 2003). method assessment when treating mixed-type data from chans systems, there are many advantages to using cluster analyses and pam with gower in particular. when cluster analysis is used, the whole dataset can be utilized rather than having to choose a priori which variables will be the most important, which has been the usual practice to treat mixed-type data to date. with pam clustering and gower, categorical variables – which are very common when assessing characteristics of people (e.g., education level or gender) – do not need to be omitted or converted table 8 pairwise comparisons between manager (a) and project (b) characte ristic cluster groups (columns) and management decisions (rows) characteristic cluster groups a) general approach federal multitaskers educated specialists coefficient p information type mixed/formal mixed 0.79 0.67 number of information sources 19 17 2.07 0.15 number of monitoring groups 3 2 0.02 0.89 number of monitoring methods 2 2 0.01 0.92 monitoring frequency > once a year every 1-2 years 2.07 0.56 number of collaborating groups 3 3 0.0006 0.98 number of science collaborators 4 4 0.59 0.44 number of researching groups 2 1 3.06 0.08 biocontrol 0.15 0.09 2.18 0.14 cut-stump 0.25 0.20 0.91 0.34 heavy machinery 0.25 0.25 0.03 0.87 burning 0.14 0.20 0.006 0.94 b) project-specific approach public private coefficient p native plant diversity 57% 84% 5.18 0.03 ecosystem resilience 47% 56% 0.55 0.46 exotic plant removal 83% 96% 2.53 0.11 habitat improvement 68% 80% 1.16 0.28 endangered species 36% 80% 0.42 0.52 channel maintenance 19% 16% 0.11 0.74 restore over-bank flooding 40% 48% 0.38 0.54 water quality 17% 20% 0.10 0.75 aesthetics 28% 60% 7.18 0.01 recreation 28% 36% 0.54 0.46 wildfire mitigation 38% 60% 3.10 0.08 livestock forage 2% 12% 3.03 0.08 other 17% 4% 2.53 0.11 none 9% 0% 2.25 0.13 biocontrol 0.13 0.06 4.44 0.04 cut-stump 0.29 0.19 2.21 0.14 heavy machinery 0.15 0.27 0.07 0.79 burning 0.18 0.20 0.0006 0.98 clark et al. 2020 / journal of environmental geography 13 (3–4), 51–60. 59 in some way to a nominal numerical value that is then improperly represented. in addition to dealing with mixed type variables, pam is also more robust to outliers than traditional methods (arunachalam and kumar, 2018; maione et al., 2018), can deal with nonsymmetrical data (gellynck et al., 2011), and can be used for relatively small sample sizes like ours as is also common with human datasets (iparraguirre et al., 2013; king et al., 2016). the gower coefficient also allows for weighting of variables and missing values in the dataset. unlike pam, gower is sensitive to outliers (sander and lubbe, 2018). despite this drawback, this analysis method is one of the best solutions to dealing with mixed data types in a multivariate setting. conclusions this study has demonstrated the application of a clustering method used in other fields of study to a chans context. pam with gower is useful in this study due to the need to comprehensively reflect complex data. in this way, managers and their decisions can be understood in a holistic manner and the cluster groupings can inform future recommendations and the allocation of resources. this method also has the potential to be useful in other chans studies such as endangered species management, grazing management, or water management where there are even more factors involved with the addition of politics and federal or state regulations. acknowledgements this research was supported by a national science foundation dynamics of coupled natural and human systems award (project number 1617463), a pustmueller grant, and the university of denver. the authors thank all managers who participated in the survey and/or interview. the assistance of carly 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(eds.) tamarix: a case study of ecological change in the american west. oxford university press, new york, 207–224. doi: 10.1093/acprof:osobl/9780199898206.003.0012 vangen, s., huxham, c. 2003. nurturing collaborative relations: building trust in interorganizational collaboration. the journal of applied behavioral science 39(1), 5–31. doi: 10.1177/0021886303039001001 williams, j.n., hollander, a.d., geen, a.t.o., thrupp, l.a., hanifin, r., steenwerth, k., mcgourty, g., jackson, l.e. 2011. assessment of carbon in woody plants and soil across a vineyardwoodland landscape. carbon balance and management 6(1), 1– 14. doi: 10.1186/1750-0680-6-11 introduction methods case study cluster analysis cluster assessment results and discussion cluster results method assessment conclusions acknowledgements references journal of environmental geography journal of environmental geography 6 (3–4), 39–47. doi: 10.2478/jengeo-2013-0005 issn: 2060-467x the advantages of using sequential stochastic simulations when mapping small-scale heterogeneities of the groundwater level lászló mucsi *1 , jános geiger 2 , tomislav malvic 3,4 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 department of geology and palaeontology, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 3 faculty of mining, geology and petroleum engineering, university of zagreb, pierottijeva 6, 10000 zagreb, croatia 4 ina plc *corresponding author, e-mail: mucsi@geo.u-szeged.hu research article, received 21 june 2013, accepted 15 september 2013 abstract in the environmental risk assessment of oil fields, a detailed knowledge of the heterogeneity of groundwater surfaces is absolutely indispensable. based on theoretical considerations, in order to analyse small-scale heterogeneities, we decided that the sequential gaussian simulation (sgs) approach seemed to be the most appropriate one. this method gives preference to the reproduction of small-scale heterogeneities at the expense of local accuracy. to test whether this kind of heterogeneity of the groundwater level corresponds to sedimentological variability, a point bar of the river tisza (south-hungary) was chosen. in variograms, the longest range was derived from the large-scale sedimentological heterogeneity of the point-bar, the medium range was in accordance with the radius of the meander and its direction coincided with the depositional strike of the meander, while the shortest range corresponded to the lateral heterogeneity of the deposits where the ground water level was measured. the similarities and differences of the realizations of sgs express the uncertainty of the map representation of the ground water surface. the e-type estimates of 100 equiprobable realizations resulted in a very detailed surface. the hydraulic gradient map obtained from the e-type estimates can provide us with a better understanding of the local flow characteristics. keywords: groundwater level, point bar, sequential gaussian simulation, sedimentology, heterogeneity, geoinformatics introduction the environmental risk assessment of oil fields highly requires a detailed knowledge of the heterogeneity of groundwater surfaces (vaanlocke et al., 2010; balderacchi et al., 2013). in many cases the contamination caused by leaks can only be identified after it has appeared in the groundwater or on the surface. therefore, the spatialtemporal analysis of the surface of chemically aggressive groundwater could help one pinpoint the most probable location of a natural pipeline leak. in order to monitor a particular environmental system, we chose the kind of methods suitable for data gathering and analysis. the primary goal of any monitoring activity is partly to locate the source of contamination, and partly to analyse its lateral and vertical dispersion. the ground water surface can be measured only in groundwater monitoring well, therefore the database can contain real data for these points. the groundwater level has to be estimated for other point. in the “traditional” gridding or triangulation method, the numerical inter/extrapolations are formulated according to the method of least squares estimation. the aim of such methods is to improve the local accuracy and demonstrate the regional tendencies (journel, 1987; deutsch and journel, 1998). in this case, the traditional estimation approaches act as “low-pass filters”, filtering out the small-scale heterogeneities affecting the principal tendencies. kriging has become a very popular estimation method (theodossiou, 1999; theodossiou and latinopoulos, 2006), and it has this filtering property. the kriged surfaces (i.e. surfaces with different geological attributes) appear unnaturally smooth, and the resulting flow and transport dispersion are systematically underestimated (deutsch, 2002). the stochastic simulations differ from kriging approaches in the following ways (carr and myers, 1985): in most interpolation algorithms (e.g. kriging) the goal is to find the “best” local estimate of the variable without specific regard to the resulting spatial statistics of the estimates taken together. in the solution, the reproduction of global features and statistics (histogram, variogram) take precedence over the local accuracy. based on the simulated groundwater surface, the analysis of contaminant dispersion could also be improved. hence knowledge of the actual position of the groundwater level as well as its flow path may reduce the environmental risk associated with the joint (combined?) effects of a high groundwater level and other natural corrosives. 40 mucsi et al. (2013) study area the largest mining and industrial area of the sout heastern part of hungary is the oil and gas plant of mol (hungarian oil and gas co.). here almost every aspect of hydrocarbon exploitation, pipeline transportation and oil processing is carried out ( fig. 1). fig. 1 the area surveyed on a landsat tm 453 (rgb) color composite. the oil, gas and thermal water wells labeled by yellow circles (mucsi et al., 2004) within the area surveyed, 100 or even 1000 km long oil and gas plant pipeline networks have been installed below the surface. in the neighbourhood of a pipeline leak, the environmental damage caused can be quite serious. for networks that were built a few decades ago, systematic pipeline monitoring should be performed due to frequently occurring natural leaks. in the area surveyed, a fairly dense pipeline ne twork links the production wells with tank farms. this area is part of the recent valley of the river tisza. the oil and gas production here, which began in the 1960’s, has significantly altered the former agrarian landscape (fig. 2). however, agricultural activity has continued in parallel with mining and oil processing (see fig. 3). therefore the risk of a pipeline leak is not just real for mol, but also for farmers. for the latter group, lower harvest yields due to poorer soil and groundwater quality may be two great causes for concern. at the end of the last century and beginning of this century, the repeated occurrence of a recor d high water level of the river tisza, a high groundwater level (see fig. 4) and the extremely dry summers may actually be the consequences of a changing global climate, and justify the need for a more co nscious use (pro-active stewardship?) of our enviro nment. fig. 2 the alteration of the former agrarian landscape of an aerial photography (1950) and a spy satellite (corona – kh4b) image from 1972 (hungarian military archive, usgs) fig. 3 ikonos satellite image from 2004 (inta spaceturk) on the surface, holocene sand, silt and clay can be found owing to fluvial sedimentation. based on sediment profiles obtained from the wells below the upper silty sandy lens-like series, a laterally extended silt layer appears 4-5 metres beneath the surface, which can be regarded as a flood plain deposit. under this series, late holocene fluvial sand dominates. originally the monitoring system consisted of 25 wells. since they are located in a cluster, we decided to supplement the original monitoring system with 17 new wells (fig.5). the advantages of using sequential stochastic simulations when mapping small-scale heterogeneities of the groundwater level 41 fig. 4 high groundwater level (aerial photography, mucsi et al, 2004) fig. 5 location map with the new and old monitoring wells theoretical considerations in general, the ground water level is determined by hydrological processes like precipitation (more precisely, its annual and long-term distribution), evaporation, transpiration, and pedological-sedimentological and topographical conditions. here, the heterogeneity of pedological or sed imentological factors may be the biggest two factors among the processes of this multivariate system. u nfortunately, this heterogeneity is not properly reflec ted in the maps of the groundwater surfaces. the purpose of this study is to demonstrate a mapping process of the groundwater level that is in consistent with small and medium scale sedimentolo gical heterogeneity by using sequential gaussian simulation (sgs, deutsch and journel, 1992). for this purpose a recent point bar sedimentary body of the river tisza (hungary) was chosen. the scales of sedimentological heterogeneity in a point bar in the idealized cross section of a point bar, the fo llowing four basic units can be identified: (1) channel lag deposits, (2) laterally accreted bar deposits with accretion surfaces, (3) a natural levee, and (4) a flood plain series (fig. 6). the bar sequence itself can be subdivided into (a) a lower point bar and (b) upper point bar series (fig. 6). it is well known that the effective porosity and permeability of a sediment are partly determined by sedimentary textures and structures that permeate the pore space distributions. the influence of sedime ntary structures and textures on permeability is very significant, not just for the absolute values but also for the anisotropy. a quite trivial conseque nce of this fact is that the steady state level of a groundw ater surface can vary according to the sedimentary structures and textures of the actual deposits. a ccording to the basic rule of sedimentology (walter’s facies law), lateral facies also occur sup erposed upon one another. it means that the vertical heterogeneity depicted in fig. 5 can also horizontally affect the spatial position of the groundwater level. the lateral scale of this heterogeneity can vary from a few m etres to tens or hundreds of metr es (pryor, 1987; mial, 1996). however, according to the gpr images, there is a textural variability that has a range of a few hundred metres to a few kilometres. summarizing the points above: in the point bar sedimentary bodies, the lateral variability of sedimentary features can manifest itself on two different scales. they range (1) from several metres to tens or hundreds of metres and (2) from several hundred metres to several kilometres. the basic unit associated with this scale (1) is the scale of the principal sedimentary structure, while for scale (2) the basic unit is the distance between two neighbouring accretion surfaces. fig. 6 idealized cross-section of a point-bar sequence (modified after brunner et al, 2001) the ground water level treated as a regionalized variable when viewed mathematically, two statements can be derived from the above description. they are: (1) the ground water level is a spatial property that can be regarded as a random variable at each data point; (2) there is a spatial relationship associated with these random variables. the first statement follows from the variability of the textural characteristics of the sedimentary body 42 mucsi et al. (2013) containing the initial water table. the second statement is a consequence of the fact that a point bar is the result of spatially interacting processes. that is, according to the definition given by cressie (1991), the water table level is a regionalized variable. a map of absolute position of a ground water level fixes the water table in the real spatial position. this kind of map is a plot of a three-variable function, which gives an estimate of the real position, or more precisely one realization of the several existing estimates. by continuing this process, the “smooth” surface in fig. 7 tells us that the variability of hydrological elements affecting the water table is “not too large”. this then leads us to ask the following question: “is the smooth surface simply the result of the gridding technique we applied?” thus, traditional methods like kriging are really appropriate for describing large-scale heterogeneities. for point bars the latter ranges from a few hundred metres to a few kilometres. the small-scale heterogeneities are simply filtered out via these estimations. in fact the traditional gridding techniques honour the large-scale features quite well. for example, in fig. 7 the lateral accretion surfaces are clearly recognizable. to overcome the above drawbacks, several methods for stochastic simulation have been developed and they have been regularly used in the mapping of reservoir properties in the oil industry since the mid 1980’s, but they have been widely applied in the environmental sciences as well (webster and oliver, 2001). the approach we adopted sgs in general let us define a regionalized variable (rv) and call it z(u). stochastic simulations are methods in which alternative and equally probable high resolution models of spatial distribution of the z(u) are generated. the realizations obtained from them are called stochastic images. if the realizations honour the input data (the data points), the simulation is called conditional. for the local set of data and conditional statistics, kriging is used as an interpolation technique which provides a simple numerical method that is the “best” in the sense that it is accurate locally. simulation provides several alternative but equally probable models, all of which are the “best” reflection of reality in a certain global sense. the differences between the realizations offer an opportunity for measuring the spatial uncertainty. the gaussian simulations honour the covariance model of the data points. this is why they are suitable for modelling processes with an extremely large continuity. let us define the common distribution of an rv by zi (i=1,2,..,n). that is, according to the above theory, let us take the data of all available points and consider the conditioning of this n rv for each type of n data sets. the corresponding conditional cumulative distr ibution function (ccdf) for this is: f(n)(z1, ... ,zn|(n))=p{zi≤zi, i=1, ... ,n|(n)} if the ground water table is treated as regionalized variable, this variable must be a random variable for any given data point. that is, in the infinitesimally small neighbourhood of any data point it will have a random value. hence the data-point value is nothing else than a random value of the corresponding rv derived from the distribution function of the infinitesimally small neighbourhood. if processes controlling the ground water table are homogeneous in the region being analysed, then the cumulative distribution function (cdf) surrounding any set of data points can be assumed to be the same as that of over the whole given region. by applying a normal score transformation on the data set, this distribution can be represented in analytical form as well. as is well known, the first two moments determine the normal distribution. this fact was incorporated in the implementation of sgs (carr and myers, 1985). sgs is a widely used simulation technique for extreme continuous data (e.g. porosity). details of the various implementations are given in deutsch and journel (1998), and in deutsch (2002). in essence, sgs models the method of iteration, since the estimation of a grid point is done based on the result of the previous step. this view corresponds to the fact that a contour map is unbiased only after the grid estimation method has been fixed (brooker, 1979). the expected value (more precisely, the “expected surface”) of the series of realizations is the most characteristic spatial distribution that describes “reality”. the difference between the realizations reflects the uncertainty of the mapping of the property being studied in our case, the surface of the water table. this uncertainty is independent of the accuracy of the measurement of the fig. 7 appearance of the lateral accretion surfaces o n the water table contours the advantages of using sequential stochastic simulations when mapping small-scale heterogeneities of the groundwater level 43 water table taken from each well. in fact, this uncertainty depends just on the heterogeneity of hydrological factors and the way in which this heterogeneity can be described using available well geometry. pre-processing: the steps involved the first phase was an analysis of the lateral distribution and probability distribution of the data (fig. 8a-b). in the second phase, two things became immediately apparent: (1) the peculiar clustering of data points; (2) the observation that there are many wells in each cluster, and these have significantly different data values (fig. 8a). however, the probability distribution of data is quite symmetrical (fig. 8b). this clustering appearance of wells is fairly common around artificial objects, where small distant wells serve the purpose of environmental protection while the larger distance wells were built for water table observations. however, this may cause problems in mapping, because the clustered wells will shadow the nearby grid points with their own values. hence the contours will not reveal the true situation. at the same time, this geometry will also affect the relative frequency histogram of the water table values. however, applying a special declustering technique can resolve this problem (deutsch and journel, 1998). with this method an appropriate grid system is placed over the area where (in such a way that?) the clustered wells can be sepa fig. 9 the variogram surface and the variogram model fig. 8 the first steps of the geostatistical analysis 44 mucsi et al. (2013) rated into individual wells. then some weighting factors can be derived which are small for the very close wells and become larger with increasing distance. in this way the shadow effect of closer wells can be eliminated. in our case the declustering method gave 500 m as the most appropriate cell distance (fig. 8c). the result of the normal score transformation is shown in fig. 8d. fig.10 the empirical (a) and model variogram surfaces (b) variography our analysis of the spatial continuity of the water table was aided by variography. a variogram surface was used for the visual examination of continuity directions (see fig. 9a). this method identified a principal direction of ne-sw. the smallest continuity may be identified in the nw-se direction (fig. 9b). these directions appear on the smooth surface of the water table as well (see fig. 7). as mentioned previously, this feature corresponds to the lateral accretion surfaces of the point bar. the second figure here shows a variogram model based on the experimental data. as you can see, this is a nested structure consisting of three units. the first component has a range of 250 m. the second one has a range of about 3.800 m, while the third has a range of 4.100 m. most likely, the latter is indicated by the ‘smooth’ map of the water table surface. the largest range is almost equal to the length of the point bar, so it may be related to the large-scale process that forms the point bar sedimentary body. the second largest range is quite similar to the previous one and may be related to the effect of a bend in the river channel going in a se direction. but the smallest range (250 m) may not be caused by hydrological effects at all, but by sedimentological effects. this may be the result of internal heterogeneity of the point bar affecting the surface of the water table. hence it is the heterogeneity which was really the object of this study. fig. 10a depicts the spatial continuity outlined above, while the second figure shows the variogram surface obtained from the variogram model (panattier, 1996). the similarity is obvious here. realizations and simulation uncertainties from the sgs, 100 equally probable realizations were generated. fig. 11 shows 3 of the resulting one hundred images. as can be seen, there are regions where the realizations are not too different. this is caused by the locally low uncertainty of the lateral interpolation (journel, 1993). fig. 11 stochastic realizations showing equally probable position of the water table the advantages of using sequential stochastic simulations when mapping small-scale heterogeneities of the groundwater level 45 fig. 12 e-type estimation from the two-hundred stochastic realizations of the relative water table position the one hundred realizations provide one hundred values estimated for each grid node. this number is quite sufficient to compute the cumulative distrib ution around an infinitesimally small neighbourhood of each grid point. that is, there is a possibility of est imating not just the expected value, but also the lower and upper bounds of the confidence interval for each grid node. moreover, we have a way of explicitly a nswering questions like “how can we calculate the lateral distribution of probabilities associated with the water table level at 72 cm below the surface?” and “which regions with a water table of 85 cm have a probability value of 0.8?”. fig. 12 shows the predicted value map of the relative water surface (i.e. its depth below the surface), while fig. 13 shows the surface of the water table above the baltic sea. the ‘smooth surface’ obtained by traditional kriging and the one obtained by the e-type estimates (expected values) of the sgs are compared in fig. 14a and fig. 14b, respectively. fig. 14b highlights the local effects of underground flow systems. the advantages of this approach in the three-phase flow simulation were described earlier (see, for instance, geiger and komlosi, 1996). their observations confirmed that these approaches make the flow simulations more effective (than earlier approaches?). fig. 13 e-type estimation from the two-hundred stochastic realizations of the absolute water table position. the black arrows are proportional with the hydraulic potential 46 mucsi et al. (2013) conclusion within the area surveyed, 100 or even 1000 km long oil and gas plant pipeline networks have been i nstalled below the surface. the spatial-temporal analysis of the surface of chemically aggressive groundwater helped one pinpoint the most probable location of a natural pipeline leak. originally the monitoring system consisted of 25 wells. since they are located in a cluster, the original monitoring system was supplied with 17 new wells whose locations were calculated with geostatistical analysis. the ground water level was measured monthly in these wells and sequential gaussian simulation was used to demonstrate a ma pping process of the groundwater level that is in co nsistent with small and medium scale sedimentological heterogeneity. a map of absolute position of a ground water level fixed the water table in the real spatial position. the developed map was a plot of a three variable function, which gave an estimate of the real position, or more precisely one realization of the several existing estimates. the analysis of the spatial continuity of water table was aided by variography. a variogram surface was used for the visual examination of continuity directions. this method identified a principal direction of ne-sw. the smallest continuity was identified in the nw-se direction. these directions appear on the smooth surface of the water table as well in variograms, the longest range was derived fig. 14 comparison of the results coming partly from kriging ( a) and partly from e-type estimation of sgs (b) the advantages of using sequential stochastic simulations when mapping small-scale heterogeneities of the groundwater level 47 from the large-scale sedimentological heterogeneity of the point-bar, the medium range was in accordance with the radius of the meander and its direction coi ncided with the depositional strike of the meander, while the shortest range corresponded to the lateral heterogeneity of the deposits where the ground water level was measured. the similarities and differences of the realizations of sgs expressed the uncertainty of the map representation of the ground water surface. the e-type estimates of 100 equiprobable realizations resulted a very detailed surface. the hydraulic grad ient map obtained from the e-type estimates determined the local flow characteristics. the subsurface contamination can spread along these pathways, so it can get far distance from its source. references balderacchi, m. ,benoit, p., cambier, p ekloc o. m., garginid, a., gemitzi, a., gurelf, m., kløve, b, nakich, z., predaai e., ruzicic s., wachniewj, p., trevisana m. (2013). groundwater. pollution and quality monitoring approaches at the european level. critical reviews in environmental science and technology 43, 323–408. brooker, p. 1979. kriging. engineering and mining journal 1980 9, 148–153. brunner, d.s.endres, a.l.sudicky, e.a. 2001. detailed ground-penetrating radar survey of a point-bar, whiteman’s creek, ontario for use in a new fully integrated 3d surface/ subsurface flow model. – geological society of america annual meeting, november 5-8, 2001. boston, massachusetts. carr, j.r myers, d.e., 1985. cosim: a fortran iv program for conditional simulations.—computer and geosciences v.11, 675–705. n. cressie 1991. statistics for spatial data. john wiley & sons, inc. new york, 892p. deutsch c.v. 2002. geostatistical reservoir modelling, oxford university press. deutsch, c.v., journel, a. 1998. gslib. geostatistical software library and user’s guide. – oxford university press, new york, 369p. geiger, j. komlósi, j. 1996. szedimentológiai geomatematikai 3-d modellező rendszer törmelékes ch-tárolókban (sedimentological, geomatematical 3d modelling system in turbiditic ch reservoirs) kőolaj és földgáz 2, 53–81. journel, a. 1987. geostatistics for the environmental sciences. – epa project no. cr 811893. technical report. u.s. epa, ems lab., las vegas, nv journel, a, 1993. modelling uncertainty: some conceptual thoughts. in: dimitrakopoulos, r.(ed): geostatistics for the next century, kluwer, dordrecht, 30–43. miall, a.d. 1996. the geology of fluvial deposits. sedimentary facies, basin analysis, and petroleum geology. – springer verlag, new york, 582 p. mucsi, l. 2001. characterisation of oil-industrial contamination using aerial and thermal images earsel symposium, drezda. in: buchroithner (ed:) a decade of transeuropean remote sensing cooperation, balkema, rotterdam, 373–377. mucsi, l., kiss, r., szatmári, j., bódis, k., kántor, z., dabis, g., dzsupin, m. 2004. felszín alatti vezetékek környezetszennyező hatásainak felmérése távérzékeléses technológiával (invesgtigation of possible environmental pollution of subsurface pipelines using remote sensing technologies). geodézia és kartográfia 56 ( 4) 3–8. pryor, w.a. 1987. permeability, porosity patterns and variations in some holocene sand bodies. in: beaumont, e.a., foster, n.h. (ed) reservoirs ii. sandstones. aapgd treatise of petroleum geology reprint series. no.4, 127–154. theodossiou, n. 1999. evaluation of the distribution of hydraulic head in an aquifer using the kriging method. – scientific journal of hellenic hydrotechnical association. hydrotechnika 9, 3–14. theodossiou, n., latinopoulos, p. 2006. evaluation and optimization of groundwater observation network using the kriging methodology. environmental modelling & software 21, 991–1000. vanloocke, r., de borger, r., voets j. p. . verstraete w 2010. soil and groundwater contamination by oil spills; problems and remedies international journal of environmental studies 8 (1-4), 99-111. webster, r., oliver, m. a. (2001): geostatistics for environmental scientists, john wiley & sons. http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28eklo%2c+o+m%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28gargini%2c+a%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28gargini%2c+a%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28gemitzi%2c+a%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28gurel%2c+m%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28kl%c3%b8ve%2c+b%29 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http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28de+borger%2c+r%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28voets%2c+j+p%29 http://www.tandfonline.com/action/dosearch?action=runsearch&type=advanced&searchtype=journal&result=true&prevsearch=%2bauthorsfield%3a%28verstraete%2c+w%29 journal of environmental geography journal of environmental geography 8 (1–2), 31–38. doi: 10.1515/jengeo-2015-0004 issn: 2060-467x modelling the hydrological effects of a levee failure on the lower tisza river tímea kiss 1* , istván fehérváry 1 , károly fiala 2 1 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2 lower-tisza water directorate, stefánia 4, h-6720 szeged, hungary *corresponding author, e-mail: kisstimi@gmail.com research article, received 10 february 2015, accepted 31 march 2015 abstract along the lower tisza river (hungary) the water level of the floods reached new record stages in 1998 and 2006, resulting in 80 cm increase in the peak flood level since the “great flood of 1970”. due to the gradual weakening of the levee-system caused by the several long-lasting floods, the question has arisen, that as in case of a levee breach or failure how would it modify the hydrological parameters of the river. the aim of the research is to create a hydrological model to analyse the effects (as stage reduction, slope and stream power) of two different levee breaches: one happening before the peak of the flood and another at the time of the flood level. the simulated levee breaching happened on the tisza river at mindszent, and the data-set of the 2006 flood was used for the modelling (at that time no levee failure happened in hungary, and it was the greatest flood in history). in the simulation the levee was broken at a point, where the channel is very close and intensively eroding, thus there is a real risk of a levee failure. if the levee would be broken a well defined area (reservoir) would be flooded, surrounded by the secondary levees and the rim of the high floodplain. during the simulation the hec-ras 4.1. arcgis 10.1 and hec-georas software were applied. the greatest changes in the hydrology of tisza occurred in the cross section where the levee breached, though the effects propagated upstream and downstream too. due to the water outflow from the tisza the greatest stage reduction effect was 1.54±0.1 m. the slope conditions changed too, as it increased from 4 cm/km to 6.5 cm/km in the upstream reach, while downstream of the failure point it decreased from 3.5 cm/km to 1.9 cm/km. at the same time the stream power increased from 4 w/m to 5.5 w/m in the upstream section, while it decreased from 3.5 w/m to 1.5 w/m in the downstream reach. comparing the results of the simulations at different stages (one at the highest stage and one at 1.0 m lower stage) it seems that the hydrological parameters did not change considerably (1%), though in a case of a levee failure at higher the reservoir reached the maximal water level sooner, though less water was stored in it, as the fall of the river was continuous. keywords: levee failure, flooding, hec-ras, flood modelling, hydrologic parameters introduction nowadays floods are the most common in natural hazards, and they cause the greatest economical losses, moreover they endanger the life of millions of people living on the flood-prone areas along rivers, especially if the inundation is a result of unexpected incidences, for example a levee or a dam failure (yalcin and akyurek, 2004). every levee breach or failures carries human tragedies and considerable losses, therefore it is important to develop detailed plans for flood-prevention and to carry out hydro-dynamic modelling of catastrophes. on the tisza river, which is the greatest tributary of the danube, the flood levels have been dangerously raised on several sections since the “great flood of 1970”, thus the flood hazard and risk increased. the seriousness of the problem is well-demonstrated by the fact that between 1998 and 2010 period the peak flood level reached new records twice, increasing the record stage by 80 cm compared to the 1970 peak flood. according to the engineers the solution of the problem of the decreasing high water levels could be the construction of flood control reservoirs that can decrease the peak flow of floods (szigyártó and rátky, 2010). the cigánd reservoir (storage capacity: 94 million m 3 ) was the first flood storage reservoir built on the upper-tisza. if it would be opened and filled up to its maximum capacity, it would decrease the flood stage by 0.25 m [1]. concerning the plans and the construction of this reservoir szigyártó (2012) expressed several critiques, as the inflow capacity of the storage lake reaches only 65 % of the required capacity. another flood reservoir was built between the szamos and kraszna rivers (capacity: 126 million m 3 ) in 2014, and the bereg reservoir is planned to be finished at the end of 2015. the upper tisza flood control system continues in the middle tisza too, where the tiszaroff (97 million m 3 ), the nagykunság (99 million m 3 ) and the hany-tiszasüly reservoirs (247 million m 3 ) were built. as the sumeffect of the operation of all these reservoirs the flood level could be reduced by 0.5-0.6 m along the river according to model calculations [1]. however, considering 32 kiss et al. (2015) the flood level increase (0.8 m) since 1970, it is not enough to reduce the flood hazard effectively. thus, we believe, that this would only be a partial solution of the problem, since the management of the floodplain (decreasing the vegetational roughness) and the widening of the tight sections are also needed. the application of models in hydrology has been started in 1960’s, by simulating the flow conditions in a channel and the seepage in porous materials (whisler and watson, 1968). by the 1990’s software groups were developed, that can model complicated hydrological systems and situations, and they have been widely applied in water management issues. nowadays the developed models able to simulate most of the hydrological processes in various conditions, but it still remains a question, what is the relation between the results and the real nature, since numeric models provide correct results, if the initial conditions and the border conditions were chosen properly. however some empirical parameters (e.g. vegetational roughness, morphological roughness) cannot be determined easily and properly, though they have significant role in modelling, which can greatly modify the results. one of the most widespread model in hydrological modelling is hec-ras (hydrologic engineering center-river analysis system). this is an one dimensional and linear model which is able to produce pseudo 3-d image with the correct ordering of cross-sections. the software is suitable to make calculations for sub-critical (froude number <1) or for super-critical (froude number >1) hydrodynamic situations besides this it is possible to build in the model detailed hydraulic constructions and structures. novelty of the hec-ras software is that it divides the cross-sections into main channel, left and right floodplain zones and it calculates the velocity and discharge for these zones, and the program finally summarizes the data. the model calculate is able to calculate water level for each cross-sections, so in the separate branches not appear locally evolved higher or lower water levels (hec-ras hydraulic reference 2010). the input datasets of the hec-ras model are the following: geometric data of the riverbed, of engineering structures (bridges, culverts etc.), water level and discharge curves, roughness parameter (pregun, 2009) which can be determined by empirical, mathematical or statistical methods (kamanbedast and esfandiar, 2011). between the hec-ras and arcgis software the connection is established by hec-georas, a toolset of arcmap program. it combines the digital elevation data with spatial analysis, thus the visualization of flooddepth and velocity characteristic becomes possible. the toolset could display the flooded areas on the digital elevation model, flood losses could be estimated, maps and illustrations cold be combined. the mike hydraulic modelling family has been developed since the 1970’s. the input data are similar to hec-ras’s (mike 11; józsa, 2001; karatzas et al., 2012), but it is appropriate to study the manning roughness in time and space, and it enables inundation simulation in 1d and 2d (mike 21) even various environments, as in rivers, cities, sewer systems, coastal areas and dam breaches. moreover the models can be used at different scales from local to regional [2]. the aim of our research is to model and analyze the hydrological effect of a levee failure by mindszent on the lower tisza river. the possibility of a levee breaching or failure is increasing by time, because (1) the repeated and long-lasting floods weaken the levee; (2) the water level of floods will probably increase further, thus it may cause overtopping; and (3) massmovements endanger the levees, as where the levee was built too close to the channel, revetments were created to stop the lateral erosion, however during the last 50 80 years the channel intensively incised (kiss et al., 2008) and the revetments were partially destroyed, thus the lateral erosion could endanger the levees. the simulated levee failure took place where in reality it is the most probable: at the given point (at mindszent) the levee is very close (20-25 m) to the river channel, and the revetment is destroyed by landslides. in the hecras model we used the data of the 2006 flood as a basis, as it was the last record flood in the region. during the research we aimed to simulate and compare the hydrological effects (as stage reduction, slope and stream power) of two different levee breaches: one happening five days before the peak of the flood and another at the time of the peak flood level. the results that are gained by the modelling of a levee failure could provide useful information for the flood control reservoir that is planned on the lower tisza too. study area the tisza river is the second largest river in hungary (l: 962 km, a 157.200 km 2 ; lászlóffy, 1982), its lower reach was chosen for the study (fig. 1). the regime of tisza is influenced by the diverse climatic characteristic of the catchments and the tributaries with frequently extreme regime. floods mostly develop at early spring due to snow melt and rainfall, and at the beginning of summer (lászlóffy, 1982). on the study area the swelling effect of danube could also be detected (vágás, 2003; bezdán, 2011). the characteristics of the study area is that the measured water level record in 1970 has been exceeded in 2000 (1000 cm) and in 2006 (1062 cm) too, and the durability of floods continuously increases (kovács, 2007; sándor, 2011). the low stages also last longer, but along the lower tisza this phenomenon is moderated by the törökbecse barrage. the difference between the lowest (70 m 3 /s) and the greatest (4200 m 3 /s) discharges is sixty-fold. during the simulated levee failure the flood flowed outside of the present-day active floodplain, into the western protected side (it is called storage area/lake in the text below). the storage area has well defined borders: secondary artificial levees are found in north and south, in east is the main levee of the tisza, and in west the natural rim of the high floodplain could be found. thus, the flooded area is actually a natural low floodplain, which was evolved in the pleistocene and holocene. there is 3-5 m difference between the low and high floodplains (her modelling the hydrological effects of a levee failure on the lower tisza river 33 nesz and kiss, 2013). on the surface of the storage lake 1.5-2 m deep paleo-channels are which could lead the flood wave into the storage area and out, however after the regression of the flood stagnant water would remain in these forms for a while. point-bars, crevasses and floodplain islands rise from the low floodplain also characteristic of this area (kiss et al., 2012). before the 19 th c. regulation works the low floodplain was periodically flooded, therefore settlements have been established just on the high floodplain or on floodplain islands. the levees in the area were built in the 1880’s and were raised several times (schweitzer, 2003). the inundated area used in the model could serve as real a flood storage reservoir, however the levees around should be heightened up to a uniform level. methods for the research we used the dataset of the 2006 flood, which was calibrated by the lower tisza hydrological directorate under hec-ras software. this flood was the highest flood in history, when the water level reached 1062 cm, thus 5.0-5.5 m deep water covered the floodplain for over 80 days. the model was uploaded by large amount of data: hydrological and morphological data of the main channel and the tributaries, cross-sections, bridge data, roughness values and the data of törökbecse barrage. the boundary conditions of the model had to be set out of the study area, because the simulated levee should not affect the boundary conditions and the starting calculation failures could be corrected. when the boundary of the model was set, it had to be considered, that (1) the tisza has very low slope in the study area (1-6 cm/km; kovács, 2007), and (2) during a previous levee failure in 1879 the flood level was reduced by 1 m. thus we assumed that the levee breach by mindszent (218 fkm) would have an affect at least on a 50-50 km-long reach downstream and upstream. therefore, the upper boundary of the model was set by szolnok (334.6 fkm) and the lower boun dary by titel (11.6 fkm). along the modelled reach the körös and maros rivers flow into the tisza, therefore their data were aldso built in the model. the boundary of the maros river reach set makó (24.3 fkm) of the körös river by gyoma (79.1 fkm). for the simulation we had to add the cross-sections of the channel. it was surveyed by the lower tisza hydrological directorate at every 100 m. however in order to model the levee breach the intervals between the cross-sections around the breach had to be decreased, using the xs inerpolation tool in hec-ras. we added 30-30 interpolated cross-sections both in upstream and downstream along a 200 m-long reach. after setting the geometrical parameters the hydrological boundary conditions in the unsteady flow simulation menu point had to be adjusted. the stage data were measured hourly, while the discharge data were mostly calculated from the water stages and some were actually measured. the gate operational data of törökbecse barrage (at 61.79 fkm) were also filled into the model. in the next step the inundated storage area had to be defined surrounded by the levees and the floodplain rim. we used the digital elevation model of the area with 2*2 m resolution with hec-georas toolset. the hec-ras software able to calculate the inundation of the area, creating its volume curve extracted with the help of elevetion range and elevation volume data tools found in the hec-georas toolset. the elevation range tool determines the altitude of the deepest and the highest points. the elevation volume data tool contains volume values related to different elevation categories (table 1). after creating these data the storage area had to be exported using the ras data tool, and then the storage area had to be imported into the hec-ras geometry dataset. the levee was built into the model as a lateral structure, because in this way a levee breach could be initiated. the geometry data of the levee were uploaded, and we set on that reach and the river kilometre on which the starting point of the levee should have been placed. furthermore, we joined the levee with the right bank and set the water would flow into the storage area on the protected side in case of levee breach. the width and the height of the levees were set in the lateral weir embankment menu point and the distance from the upstream cross-section in the weir stationing menu point. fig. 1 the study area is located on the lower tisza. in the model the flood would destroy the levee and inundate a flood protected area (reservoir) 34 kiss et al. (2015) table 1 required data for filling up the storage area height (m asl) volume (m 3 ) area (ha) –74.5 0 10890 74.51–74.56 522.70 10890 74.57–74.64 1317.47 13335 74.65–74.72 2227.90 16895 74.73–74.83 3814.74 21065 74.84–74.96 6242.60 26005 74.97–75.11 9773.72 32625 75.12–75.30 14956.79 38285 75.31–75.52 22415.91 68235 75.57–75.78 39571.46 97765 75.57–76.10 122167.22 885775 76.11–76.48 474995.47 1484965 76.49–76.94 2279174.25 6473645 76.95–77.49 8573056 19036124 77.50–78.15 30234490 64933576 78.16–78.94 86709024 109962880 78.95–79.89 182364640 132163272 79.90–81.03 307073664 140241056 81.04–82.39 460514816 141567792 82.40–84.03 646742528 142157424 84.04–86.0 870831232 142212288 the modelled levee breach or failure was created by mindszent (218 fkm), where the levee is very close to the river (20-25 m), the revetment have been partly destroyed and the levee is threatened by landslides. besides, the area behind is the deepest part of the simulated storage lake, thus the paleo-channel which starts exactly at the levee failure point could control the inflow and outflow of the flood. the simulated levee breach would totally destroy the levee along its 60 m length within 6 hours with an even rate. the steepness of the breached surface is 1-1° on the left and on the right side therefore the breached surface has trapezoid shape. the coefficient of the levee mat erial was set to 2.6, considering that it was built of soil and loose sediments. as we aim the simulation of two levee failures, in the first case the levee breach occurred at 958 cm flood level (equals to 84.4 m altitude, or 1 m before the peak stage) and in the second case by the levee failure happened at the highest stage at 1058 cm (85.3 m altitude). after adjusting the boundary and the initial conditions the plan data was compiled by selecting that geometry and unsteady simulation file that should have been used during the simulation. the initial (2006.03.22. 7:00) and the final (2006 5.31 7:00) dates were also set in the plan data window. this period cover the whole duration of the 2006 flood. the hydrograph output interval menu records water stage and discharge values into a file in given time intervals. as the water level measured in every hour at the gauging stations, 1-hour interval for the output was selected. the results of the model were validated using the measured data of the 2006 flood. during the process the values calculated by the model and the real measurement data were exported into an excel table. the accuracy of the model was ±0.1 m within the studied period, however during the last ten days of the falling stage the error became as high as ±1.0 m, which could be explained by the special characteristics of the 1-d model. results levee failure prior the peak flood (at 958 cm) if during the 2006 flood the levee would have been breached at mindszent at 958 cm stage, and the flowing water would erode a 60 m wide opening on the levee in six hours, the maximum discharge of the out-flowing water would be 1255 m 3 /s (fig 2). the flood storage area (113,7 km 2 ) on the protected side of the levee would be filled up to 84.5 m asl. at the end of the process ca. 700 million m 3 water would flow into the reservoir. the greatest volume would be stored on the 13 th day after the levee breach, as afterwards the water would start to flow backwards to the tisza. fig 2 the water level and the water inflow curves of the reservoir in the case when the levee breached before the peak-flood at 958 cm stage comparing the simulated water stages of the neighbouring gauging stations to the 2006 stage data (without levee failure) it could be stated, that the ma ximum stage-reduction effect is 1.54±0.1 m at the mindszent (218 fkm) gauging station (fig 3). at the t iszasziget gauging station (167 fkm) ca. 50 km downstream from the levee failure this effect decreases to 1.2 ±0.1 m, while upstream at csongrád (246 fkm) it is only 0.68±0.1 m respectively. the greatest degree of stage-reduction appears on almost all gauging stations on the same day, 6 days after the levee failure. modelling the hydrological effects of a levee failure on the lower tisza river 35 fig 3 maximal stage reduction effect of the two simulated levee failures the simulated hydrograph reflects stage drop by approximately 50 cm on the day after the levee failure, though after 6 days the stage increases again and reaches a peak at 965 cm, which level is 7 cm higher than the water level when the levee breached (fig 4). the maximum height difference between the simulated hydrograph and the real stage curve of the 2006 flood is the greatest at mindszent (0.78±0.1 m), and it decreases upstream and downstream, in the function of distance from the point of the levee failure. fig 4 hydrographs of the 2006 flood (a), of the simulated flood with levee failure at 958 cm stage (b), and of the simulated flood with levee failure at 1058 cm stage (c) after the peak stage the water level drops. simultaneously, the water level in the reservoir falls too, due to back-flow towards the tisza. this increases the stage of the tisza by up to 0.79±0.1 m at the crosssection where the levee failure occurs. in the last 10 days of the simulation the model counted by greater error (±1.0 m), therefore only the existence of the phenomenon of water level rising could be proved, but exact values of the process and the emptying of the reservoir within the simulated time interval could not be studied in detail. based on the calculations of the simulated levee failure the average slope of the tisza increases from 4 cm/km to 6.5 cm/km on the upstream section between csongrád and mindszent, while on the downstream section it decreases from 3.5 cm/km to 1.9 cm/km (fig. 5). at the same time the stream power of the river on the upstream section increases from 4 w/m to 5.5 w/m, while it decreases on the downstream section. the greatest decrease from 3.5 w/m to 1.5 w/m was calculated by mindszent (fig. 6). fig 5 slope changes of the tisza river after a levee failure at mindszent fig 6 stream power changes of the tisza river after a levee failure at mindszent levee failure at the peak of the flood (1058 cm) in the second simulated case the levee failure would occur at the peak of the flood (1058 cm), and the levee would be destroyed along a 60 m long section. in this case the maximum discharge of the outflow (fig. 7) would be much higher (1698 m 3 /s) than in the previous case (1255 m 3 /s), therefore the reservoir would be filled up in 11 days (shorter by 2 days) up to 84 m asl, which is 0.5 m lower than in the first case. altogether 650 million m 3 water would be stored in the reservoir, less by 50 million m 3 than during the first simulated levee failure. it could be explained by the different hydrographs of the two cases: in the first case the levee breaches 1.0 m before the peak flood, thus the outflow got high amount of water supply for another 6 days, until the flood starts to fall. however, in the second case the levee failure occurs at the peak of the hydrograph, thus the falling limb of the flood supplies less water, thus the amount of outflow decreases too. fig. 7 the water level and the water inflow curves of the reservoir in the case when the levee breached at peak-flood 36 kiss et al. (2015) the maximum values of the diminution effect of the two simulated levee failures do not change significantly (1%), so the diminution effect would be 1.54-1.52 m (fig. 4). during the second simulation the maximum value of diminution appears 5-6 days after the levee failure, which is one day shorter than in the first simulation case. the backflow into the tisza would be very similar as in the first simulated case. comparing the simulation of the levee breach at the peak of the flood with the simulation of the levee failure at 1.0 m lower stage, it seems that the changes in slope are not significant (<1%). although the slope on the upstream (csongrád–mindszent) section increases to 6.3 cm/km, which is slightly lower than it was during the former simulation. on the downstream section between algyő and mindszent the slope decreases to the same value (1.9 cm/km). considering the stream power the trends in both cases are similar, as it increases considerably on the upstream section from 3.3 w/m to 5.5 w/m, while downstream of mindszent it reduces significantly from 4.1 w/m to 1.4 w/m. discussion usually levee failures occur due to levee overtopping, as it happened during the most disastrous hungarian floods of the tisza: in 1879 szeged was destroyed by the flood, or in 2001 a levee failure by tarpa destroyed several settlements in the upper tisza region. so in the second simulation we supposed overtopping, however in the first case we simulated a levee failure that occurred at 958 cm water stage, so at 1.0 m lower stage than the peak of the flood. in this simulated case overtopping is impossible, but the slide of the levee is very probable, as landslides endanger the levee due to very active incision of the channel. besides, the results of this simulation could be applied if the levee would be opened consciously with flood-protection purposes, so the protected side could be used as a flood control reservoir. after the levee failure the filling up of the reservoir area would be controlled by the hydrology of the flood wave and the characteristics of the relief. in the model the initial point of the filling up is the deepest point of the area, however it could be considered as the gross error of the model, since in reality the filling up does not begin at the deepest point, but at the site of the levee failure. thus, applying the hec-ras only the hydrological changes of the tisza could be simulated. the water outflow into the protected floodplain area changes significantly the hydrological parameters of the tisza. the greatest changes occur at the cross section of the levee failure (mindszent, 218 fkm), as the largest flood diminution effect (1.54±0.1 m) could be observed here. towards downstream the effect would decrease, so at tiszasziget (50 km far from mindszent) the maximum diminution effect would be just 1.22±0.1 m (fig. 3–4). the small difference could be explained by the small slope (1.9-3.5 cm/km) of the river. the levee breach also causes flood diminution towards upstream, however its degree is reduced by the arriving flood wave. comparing the hydrographs with and without levee breach the date and the degree of the maximum diminution effect could be determined. the simulated levee breach (at 958 cm stage) occurred on april 16 th and the greatest diminution effect ensued six days afterwards along the middle section of the river (mindszent–algyő– szeged), but it developed one day later at the further gauging stations (csongrád and tiszasziget). the temporal coincidence of the maximal diminution effect on the gauges could be explained by two reasons. first of all the effect of the levee breach is pronounced for 6-8 days until the outflow-discharge (towards the reservoir) is over 1000 m 3 /s, thus great part of the floodwater supply coming from the upstream is drained off. on the other hand, the peak of the 2006 flood occurs exactly 6-8 days after the levee breach so the diminution effect coincides with the duration of the rising limb of the arriving flood-wave. the date of the peak of the 2006 flood without levee breach (at mindszent april 22 nd ) precedes the date of the peak of the flood with levee breach at 958 cm stage (at mindszent april 28 th ). it could be explained by the fact that the out-flowing water from the tisza is able to decrease the water stages of the river only at a particular discharge (in this situation 1000 m 3 /s) and only for a certain time (in this case for 6-8 days) against the water supply from upstream. after the reservoir is filled up, the amount of inflow water decreases, and the diminution effect terminates. the occurrence of a levee failure has the greatest probability at the peak of a flood. comparing the values of the two simulations it seems, that in case of the peak-stage levee failure the processes are more rapid. thus, (1) the outflowing discharge increases by 35%, (2) the filling up of the reservoir lasts 2 days shorter, (3) the water level in the reservoir is 0.5 m lower due to the falling stage of the tisza and the resulted decreasing water supply, and (4) in the reservoir the amount of stored water is less by 50 million m 3 . these processes are reflected on the hydrographs of the out-flowing water (fig. 2 and 7): the hydrograph of the outflowing water of the levee failure at peak-flood decreases steeper, since the water supply from the river is becomes limited. however, between the two simulations the values of the greatest stage reduction does not change significantly, probably because in both cases almost the same amount of water flows out to the protected side. the maximum stage reduction occurs one day earlier in case of the second simulation (at peak-flood), which is probably in connection with the higher stage (thus higher local slope) and the greater out-flowing discharge. the slope conditions within the main channel are greatly affected by the levee failure and the out -flow, though there are only slight differences between the two scenarios. this similarity could be explained by that the stage reduction in the two cases reached almost the same degree. the stream power highly depends on slope and discharge. thus in case of a levee failure the slope increases on the upstream section of the levee failure, therefore the stream power increases considerably, whilst on the downstream section it decreases. (in the case of szeged modelling the hydrological effects of a levee failure on the lower tisza river 37 the maros river also influences the stream power locally, therefore the simulation resulted much higher stream power values.) the changes in slope and stream power values are in connection with distance from the location of the levee failure, as by increasing distance the effect decreases. conclusions the aim of the presented research was to analyze the hydrological effect of a possible levee failure by mindszent, when the western levee would breach (or opened consciously) along 60 m length and the flood would inundate a confined flood-bay or reservoir. as the basis of the simulation a hec-ras model was applied using the data of the 2006 flood from march 22 until may 31. during the study we assumed, that the reservoir has uniform border (levee) heights. we ran the model for two cases: (1) the levee failure o ccurs at a stage 1.0 m lower (958±10 cm) than the peak flood, and (2) the levee failure happens at the peak of the flood (1050±10 cm). the results of these simulations were compared. in the first case the maximum out-flowing discharge would be 1255 m 3 /s, whilst in the second case it is 1698 m 3 /s. the reservoir (113,7 km 2 ) would be filled up to 84.5 m asl in the first case, while in the other case just to 84.0 m asl, because in the latest the falling limb of the tisza could supply less water into the reservoir. consequently in the first case the reservoir would be filled up in 13 days by 700 million m 3 water, while if the levee failure occurred at the peak-flood only 650 million m 3 water would out-flow to the reservoir in 11 days, and after that would the water would flow back to the tisza from the reservoir. the greatest changes in the hydrology of the tisza occur in the close vicinity of the levee failure, but there are only 1% difference between the two levee failure scenarios. in both cases the greatest stage reduction (1.52-1.54±0.1 m) appears at mindszent. on the downstream section at tiszasziget (50 km far from mindszent) the stage reduction is only 1.18-1.22±0,1 m, whilst on the upstream section at csongrád (30 km far from mindszent ) it is even smaller (0.84-0.86±0.1 m). on the upstream section the stage reduction effect is lessen by the water supply from further upstream. if the levee breached at a stage 1.0 m lower than the peak of the flood the maximum of the stage reduction would appear 6-7 days after the levee failure, though it would be faster by 1 day in the second case, due to higher initial water out-flow. yu (2013) also studied levee failures at various water levels applying laboratory experiments, and he found that if a levee failure occurred at higher stage the processes are faster. in case of levee breach at lower stage, the date of the peak-flood shifted in time, for example the peak of the flood at mindszent occurred 6 days later and at lower stage by 0.78±0.1 m than the original 2006 flood-wave. both simulations prove that the water flowing backwards form the reservoir to the tisza increases the water level of the falling tisza by maximum 0.74 m. however in this period the accuracy of the model decreases, therefore the dynamics and the effect of the backflow were not examined in detail. as a result of the levee breach the slope conditions of the tisza alters significantly by the same degree regarding both simulations. on the upstream section, between csongrád and mindszent the slope increases from 4.0 cm/km to 6.5 cm/km while downstream of the levee failure it decreases from 3.5 cm/km to 1.9 cm/km. the degree of the slope change decreases proportionately by distance from the point of the levee failure. the levee breach influences the stream power too. at the first simulation (at 958 cm stage) the stream power increases from 4.0 w/m to 5.5 w/m on the upstream section at csongrád, while downstream of mindszent it decreases significantly from 3.5 w/m to 1.5 w/m. in the second case (at 1058 cm stage) the stream power increases from 3.3 w/m to 5.0 w/m on the upstream and decreases from 4.1 w/m to 1.4 w/m on the downstream section. the alteration of slope conditions and the stream power could effect the channel formation. on the upstream sections due to the 50% rise in these values intensive bank erosion and incision could take place, and as the sediment transport could become more intensive, the overbank floodplain aggradation will accelerate. meanwhile the values on the downstream section halves, so the transportation of the sediment slows down, thus in the channel accumulational processes and intensive mid-channel bar and point-bar formation could be characteristic. the results of the study could be applied in flood management, since in case of a levee failure or during a controlled levee opening similar hydrological processes could be expected. however, every flood is unique and our model was based on the record high flood of 2006, thus the model should be calibrated and run on another floods, so the results could be generalized. the construction of the “szeged flood reservoir” is among the plans that would increase the flood safety of the nearby areas of the tisza, however its planned area (67 km 2 ) is less by 40% than the reservoir area we used during the simulations. therefore, it would reduce the flood levels only by 0.4 m (bódis, 2010), though in our model the flood level decrease would be at least three times greater. in order to verify which plan would be more profitable, the economic value of the reservoir area should be calculated. the levee failure in 1879 ensued at lower water level (806 cm) by petres, but the location of the levee failure was only few km far from the simulated location. the flood inundated the same reservoir, but after breaking several secondary levees it flowed further south and destroyed szeged. during this levee failure the stage of the tisza was dropped by ca. 1.0 m (dégen, 1969), which is quite similar to the simulated event, showing the validity of the model. applying the swan program borza (2008) also simulated the effects of a levee failure based on the data of the 2006 flood, and he found that the discharge of the outflow could be 1300-1400 m 3 /s and the water level would be dropped by 1.1 m, which are very similar to our values and it confirms the utility of the hec-ras model. 38 kiss et al. (2015) acknowledgements the research was supported by the otka 100761 research found and the bolyai jános research scholarship of the hungarian academy of sciences. we have to say thank to r. sági, b. benyhe and s. kovács, who supported the study by data and lots of good advices. references bezdán, m. 2011. a szabályozott tisza vízjárása tulajdonságai a tiszafüred alatti folyószakaszokon. (hydrology of the tisza downstream of tiszafüred) phd dissertation, szte tfgt, szeged, 120 p. (in hungarian) bódis, k. 2010. digitális domborzatmodellek és alkalmazási lehetőségek az árvízi kockázatelemzésben. (dtms and their application in flood risk management) jatepress, szeged, 172 p. (in hungarian) borza, t. 2008. a sövényházi ártéri öblözet lokalizációs tervének felújítása 2d árvízi elöntés modellezés segítségével. (2dmodelling of the sövényháza reservoir) diplomaterv, bme vízépítései és vízgazdálkodási tanszék, 67 p. (in hungarian) dégen, i. 1969. vízgazdálkodás i. 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(in hungarian) schweitzer, f. 2003. folyóink hullámtereinek fejlődése, kapcsolatuk az árvizekkel és az árvízvédelmi töltésekkel (floodplain development and floods) in: teplán i. (ed): a tisza és vízrendszere. mta ttk, budapest, 107–117. (in hungarian) starosolszky, ö. 1996. gondolatok a hidraulikai modellezésről. (introduction to hydraulic modelling) vízügyi közlemények 78(2), 166–171. (in hungarian) szigyártó z., rátky i. 2010. eljárás a vásárhelyi terv továbbfejlesztése során előirányzott árvízi tározórendszer hidrológiai méretezéséhez. (handbook for planning flood-storage reservoirs) hidrológiai közlöny 90(2), 25–35. (in hungarian) szigyártó, z. 2012. a kiskörei-tározó hatása az árhullámok ellapulásra. (the effect of the kisköre storage lake on floods) hidrológiai közlöny 92(2), 25–31. (in hungarian) u. s. army crop of enginners. 2010. users’s manual of hec-ras river analysis system 4.1. vágás, i. 2003. az 1998. novemberi árhullám hidrológiai értékelése a tisza-völgyi árvizek sorában. (hydrology of the 1998 flood) in: szlávik, l. (ed.): az 1998. évi árvíz. vízügyi közlemények különszám 1, 85–91. (in hungarian) whisler, f.d. watson k. k. 1968. one-dimensional gravity drainage of uniform columns of porous materials. journal of hydrology 6, 277–296. doi:10.1016/0022-1694(68)90104-2 yalcin. g., akyurek, z. 2004. analysing flood vulnerable areas with multicriteria evaluation. international archives of photogrammetry remote sensing and spatial information sciences 35(2), 359–364. yu, m. 2013. investigation of non-cohesive levee breach by overtopping flow. journal of hydrodynamics 25(4), 572–579. doi:10.1016/s1001-6058(11)60398-4 references from the internet [1] http://www.evizig.hu/vasarhelyi/vasarhelyi.asp [2] http://www.mikepoweredbydhi.com/products/ http://doktori.bibl.u-szeged.hu/1084/ http://doktori.bibl.u-szeged.hu/1084/ http://www.evizig.hu/vasarhelyi/vasarhelyi.asp http://www.mikepoweredbydhi.com/products/ microsoft word mokbel_et_al_2021_final journal of environmental geography 14 (1–2), 24–37. doi: 10.2478/jengeo-2021-0003 issn 2060-467x environmental factors that influence the geography of yemen leading to dust and sand storms a case study wadie ahmed mokbel ghalib1, almoliki mohammed mansoor2, sajan chimmikuttanda ponnappa3* 1taiz university, faculty of medical and health sciences, laboratories department, taiz, yemen 2taiz university, faculty of art, geography department, taiz, yemen 3r and d, chemistry, verdeen chemicals pvt. ltd, d-11, upsidc industrial area, masoorie-gulawati road, hapur district, uttar pradesh, india-201015 tel.: +90 (542) 3032275 orcid id: 0000-0002-5759-1089 *corresponding author, e-mail: sajan.saj@rediff.com research article, received 11 november 2020, accepted 5 april 2021 abstract in yemen, the dust storm is a common phenomenon severely affecting the economy and health. yemen is located in a semi-desert desert area, where dust and sand storms occur all year round, however they are the most common at summer (from june until the end of september). coastal areas (hajjah, hoddeidah, taiz, lahg, aden, abyan, shabwah and hadramout) and desert areas (marib and al jowf) are affected by dust and sandstorms almost all year round. the western and central governorates of yemen are mountainous regions, but influenced by dust too. dust storms in yemen have an impact on humans, animals, plants and all environmental ecosystems. in this article, we attempted to understand the possible relationship between environmental parameters such as wind temperature, and precipitation, which influence the development of dust and sand storms in and around yemen. statistical analysis such as descriptive statistics, t-test, anova one-way test, tukey test, levene test, and correlation test were performed. the statistical analysis confirms that there is a significant correlation between wind, temperature and precipitation at 0.01 and 0.05 levels. the results further depict that environmental factors play a vital role in the formation of dust and sand storm. the results obtained are encouraging and further research will be conducted based on technological evidence. keywords: dust storms, desert, wind, temperature, atmospheric pressure, yemen introduction sandstorms and dust storms are caused by strong high winds, which erode sand and sandy soils from arid and semi-arid environments and release them into the atmosphere (goudie, 1988). the atmospheric dust is an integral part of the earth's atmosphere that has a direct impact on air quality and climate (yin et al., 2002). dust storms are frequent natural phenomenon in desert areas (goudie & middleton, 2001; rezazadeh et al., 2013). strong winds move dust and sand from the deserts and surrounding areas over long distances, triggering these incidents (pye, 1987; knippertz et al., 2007). the northern hemisphere is home to the world's largest dust source regions. they are found in north africa, the middle east, east asia, and north america and are known as the "dust belt." in contrast, the southern hemisphere has less land; dust sources are found in australia, south america, and south africa and they are smaller in scale (miguel, 2017). dust storms have been widespread in the favonian (west wind), saharan, and arabian regions. dust storms that originate in the gobi and taklimakan deserts are only found in east asia (southern mongolia and northern china). however, prevailing winds bring the aerosols eastward, passing through china, korea, japan, and the north pacific on their way to the hawaiian islands and the western united states (orlovsky et al., 2013). rarely, significant concentrations of dust can be carried as far as the western united states. dust storm, originating in the sahara region, travel through western sahara, tunisia, algeria, morocco, west africa, sudan, somalia, ethiopia, the canary islands, the mediterranean coast of malaga-alicante, etc. in case of arabian dust storms, dust is blown from the deserts of egypt, saudi arabia, iran, iraq, and pakistan and from the surrounding areas into the arabian sea, the red sea and the arabian gulf (pease et al., 1988). dust storms affect the majority of the middle east, in addition to the african sahara region (barnum et al., 2004; rezazadeh et al., 2013; furman, 2016). the arabian peninsula is well-known for being one of the world's most prolific sources of dust storms (fig. 1; luo et al., 2004; prospero et al., 2012). the arabian peninsula's large dunes, the deserts, the geologically diverse terrain with little rainfall, and sparse vegetation cover are the main sources that evoke dust in the air (a1-sanad et al., 1993; shepherd et al., 2016). on average, in every year yemen has one to five dust storms with a visibility of less than 1 km (middleton, 1986). location, topography and climatic conditions are the key factors that caused sand and dust storms in yemen. dust storms have a serious impact on health, infrastructure, economy, agriculture, etc. as the mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 25 fig. 1 satellite image showing the dust storms over the republic of yemen and the middle east (modis image taken by tera/aqua satellite, 2008) dust storm is a meteorological phenomenon, it is impossible to eliminate it (middleton, 2001). however, by understanding the environmental factors that lead to duststorms, we can minimise their environmental impact. in this study, we have aimed (1) to understand the interaction of environmental factors that play key role in the development of dust and sandstorms; and (2) to highlight their impact on human health and the yemeni environment including merits and demerits. in addition, (3) we are proposing possible measures to be taken by the authorities to mitigate the impact of the dust and sand storms on the region of yemen. study area the geography of yemen the republic of yemen between 12ºn and 19ºn is located in a tropical region and has all the general characteristics of the tropical region concerning the climate and its geographical determinants, except for local differences. within a tropical climate zone yemen is situated in a desert to the semi-desert region (country profile: yemen, 2008). it is within the orbital zone of deserts extending from the east coast of the atlantic ocean to morocco and, mauritania, and further to the east of the arabian peninsula and continues to iran. this expansion of deserts has a serious impact on the dust and dust storms in large parts of the republic of yemen. yemen is located in the southwestern part of the asian continent and the south of the arabian peninsula (cullen, 2005). this geographical location is close to the continent of africa. saudi arabia borders yemen in the north, and the two countries share rub' al khali, one of the world's driest deserts, and a major source of dust in the arabian peninsula. the south of the country is surrounded by water bodies. the impact of the arabian sea and the indian ocean on the territory of yemen differs from the impact of the northern and eastern continents. based on the geography of yemen, there are variations in environmental factors, such as atmospheric pressure, wind and temperature, which cause dust or sandstorms in the territory of the republic of yemen. the topography the territory of yemen is divided into two distinct topographical regions from the point of the dust and sand storms (fig. 2). the first region is the hotspot for dust and sand storms, while the second represents the environment where dust and sand storms occur. the first region includes the west, south, and south-east coastal plains, as well as the rub' al khali desert, and this large area is a source of dust and sand storms. meanwhile, dust and sandstorms are coming in from the outside of yemen's geographical borders too. the second region includes the western highlands, hadramout plateau, and interior basins. due to the wide distance between the source and the receiving location, this region is mostly affected by dust rather than sand storms. the climate yemen's climate can be characterized as a subtropical dry, hot desert climate with little annual precipitation. yemen's summer lasts from june to september. in the summer, the temperature is high (40°c), and the amount of rainfall is very limited. the winter is colder, while the spring and autumn are mild. rain usually appears in the spring, but only on rare occasions. in the dry periods the hot winds known as shamal carry dust, and blow in the spring and summer (i.e. between march and august). the most important factor in the occurrence, transfer, and spread of dust and sand storms is the climate. the formation of dust and dust storms is directly related to various climate elements such as heat, rain, wind conditions, pressure, humidity, and solar radiation. it spreads as the drought worsens, causing temperature changes, changes in wind speed, and changes in wind direction (climate change profile: yemen, 2018). the driving force behind all aspects of climate is atmospheric pressure. winds are created by differences in atmospheric pressure in different areas or layers of the upper atmosphere. the wind is one of the most important outputs for determining atmospheric pressure differences on the ground or in the upper atmosphere layers. it is also one of the most powerful factors in the movement of dust and sand storms. during the study of dust, it is necessary to analyze the wind moment because the wind is the energy that carries and spreads the dust by its direction (rafferty, 2011). seasonal variations in atmospheric pressure and winds result in the formation of various types of wind and breeze, such as: local wind is produced by a change in local air pressure. atmospheric depressions are formed as a result of these winds. west and south of yemen there are water bodies while highlands and lowlands of different natural terrain areas characterize the land of the country. the land surface is more exposed to sunlight triggering a frequent local and seasonal breeze known as land and sea breeze (allaby & garratt, 2007; winter et al., 2020). the key factors 26 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. driving the land and sea breeze are variations in temperature and air pressure between dry land and the adjacent water bodies. in case of land breeze the land cools faster than the sea, allowing the air in contact with it to cool. this causes air to sink over the land, allowing sea air to replace it at a high level. the land breeze is a low-level flow of cool air from the land to the sea (allaby & garratt, 2007; davis et al., 2019). sea breeze forms when the wind blows from the sea to the land throughout the day. the frequency of the sea breeze is determined by a variety of factors. this involves the area and level of the water, the temperature difference between land and water, the prevailing winds, the coastal topography up to 15-50 km from the coastline areas, and the prevailing wind direction of more than 100 km, all of which contribute to high relative humidity and supporting temperatures in coastal areas. the temperature of the coastal areas directly affects human comfort in the summer by altering the effect of the sea breeze on the yemeni coast, resulting in temperature variations influencing air pressure and wind direction (allaby & garratt, 2007; crowther et al., 2019; davis et al., 2019). the blowing wind, the extension of the coastal area, and the natural mountain barriers all influence the sea breeze reaching the west and southern coasts. in the summer, the sea breeze has the greatest effect on the west coast, reaching up to 80 kilometres with a maximum wind speed of 7 m/s. the effect of the sea breeze on the southern coast approaches 80-100 km/h. this is due to the regressive strength of the pressure, the lack of a winding coast, and the lack of mountain barriers to alleviate the high summer heat. in winter, the sea breeze is weak compared to summer due to high pressure, which replaces the low pressure that blocked the flow of sea breeze to long-distance inside the coast, where its impact on the west coast between 40-60 km/h with a maximum speed of 3.5 m/s. the valley and mountain breeze blows in places with a lot of topographical contrast. during the day, temperatures rise at the bottom of valleys, causing depressions and the air rises, causing its density to drop and the air to rise upwards the mountain peaks in the form of upwards foot winds known as valley breezes. these valley breezes are the persistent winds that bring warm air upwards, assisting in the growth of numerous trees. the self-cooling mechanism happens as air travels upwards, allowing water vapor to condense and form fog. furthermore, some cumulus clouds form over the high mountain peaks when the air humidity is higher and the altitude is higher. the interaction of the air with the foot of the mountain in low-lying areas or restricted areas between mountainous areas during the night induces rapid heat loss by radiation, resulting in cold air in the surrounding. if the temperature decreases, the density of the air rises, causing cold air to slide down in the form of soot winds, which pass down into the depressions and are known as mountain breezes (baumbach & vogt, 1999; allaby & garratt, 2007). this decreases the temperature and, on rare occasions, causes frosts in the winter, resulting in crop losses in kaa al hakl, jahran, ma'abar, and ka'a amran. as a result, farmers cover certain fields to shield them from frost. fig. 2 topographical map of the republic of yemen mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 27 fohen winds are warm and dry. by compressing when they land on the mountain slopes, these winds gain heat on their own (gaffin, 2007). because of the mountains and depressions in yemen, this is a natural air phenomenon. the central depression arises in the valley of al jowf. it's also caused by a difference in air pressure at the foot of the mountains that developed as a result of temperature variations (gaffin, 2007). the temperature difference in the mountains is determined by the level of the area exposed to sunlight. the high-pressure winds result in travel into the hills, leaving the depressions, and the air above the depressions increases, allowing the temperature to rise. another reason in its development is that when humid winds hit the mountains, they rise on the mountain slopes, forming clouds and precipitation. they land on the other side of the slopes (the rain-shadowed foothills), where their temperature rises spontaneously due to compression during their landing beneath the feet of mountain slopes. plants and crops benefit from these winds because they speed up the start of the growing season. (sweeney et al., 2010; iizumi & ramankutty, 2015). the al ghawbah is a local name for wind in aden, lahg, and their surrounding areas. in the summer, these winds, along with the southwestern winds, are caused by thermal depressions and dustladen winds. the geography of an area surrounded by sand is the primary cause of dust-laden wind, which causes obstructed vision, and blocked sunlight. with a speed of 40-60 km/h and a frequency of 18-21 per day, they cause environmental and human disasters. summer and autumn are the seasons when these winds blow, and they usually come from the north and west. the warm (al-kawi) winds blow from the interior desert areas of the rub' al khali (the empty quarter) desert in the summer and spring. to reach the coastal areas, the thermal depressions move south to the aden gulf and the arabian sea. these are hot winds that cause an increase in air temperatures or a dusty drying of agricultural land. they are common in aden, lahg, shabwah, bayhan, and in other northern governorates. materials and methods wind, temperature, and precipitation data were gathered from 28 stations located throughout the county (fig. 2). for each parameter, 84 samples were taken for each season, totaling 336 samples per year. as a consequence, the total number of samples for all three parameters is 1008. an anemometer model windtronix 2 was used to measure wind speed, a horiba thermometer and thermography was used to measure temperature, and a rain gauge was used to collect precipitation data. these data were then statistically analysed using the origin 8 and spss 19 versions of the software. these data will assist in the understanding of the interactions between environmental factors that affect dust and sand storms. during the overall research period, data were collected for seven years, from 2010 to 2016, for all seasons. statistical analysis such as descriptive statistics, t-test, anova one-way test, tukey test, levene test, and correlation test were performed. descriptive statistics descriptive statistics is a technique for calculating the central tendency and spread of a set of data. the central tendency for wind speed, temperature, and precipitation was calculated in this study. t-test was performed based on the results of the descriptive statistics. a t-test is a useful tool for determining whether there is a significant difference between the means of two groups that are related in some way. correlation test the correlation test is a statistical method for evaluating the degree of a linear relationship between two variables. the range of correlation analysis is between 1 and 1. if the values obtained are closer to 1 or -1, there is a clear positive linear relationship between the variables being correlated; however, if the values obtained are closer to 0, there is no linear relationship between the variables being correlated. results seasonal changes in atmospheric pressure and wind in yemen, the annual atmospheric pressure and wind data can be divided into four periods based on the seasons mentioned below. atmospheric pressure and wind during winter during the winter season the superheat center travels towards the southern hemisphere therefore the northern hemisphere would be colder. in the meantime, the water bodies hold the temperature and become warmer than the land. over siberia, a high asian atmospheric pressure (siberian) is formed (midasia, arabian gulf, eastern, and central of arabian peninsula). the high atmospheric pressure is generated in the atlantic ocean's north, spreading eastward which include north africa. the high atmospheric pressure is developed between the height of the arabian peninsula and the height of the sahara desert. the atmospheric pressure values range between 1018-1020 mbars (allaby & garratt, 2007). the mediterranean sea's water bodies are dominated by low atmospheric pressure, caused by the thermal variations between the warm water and the surrounding landmasses. the arabian sea, the gulf of aden, the red sea, the abyssinia plateau, sudan, the equator zone, and southern africa are all affected by the low atmospheric pressure. the dry and cold wind is produced in central north asia and the arabian peninsula, and it travels towards the low atmospheric pressure centers in the indian ocean's north. this is due to variations in atmospheric pressure and heat distribution across the world; triggering northern and northeast winds (collier and corporation, 1957; yiannopoulos, 2018). yemen and the rest of the arabian peninsula are affected by these winds, which keep the temperature steady and bring winter rain. in 28 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. general, the temperature of these winds is near 0°c, but in the highland areas of yemen, it can drop below 0°c, retaining the temperature of the surrounding area. the collision of cold and warm air masses caused by the wind moving through water bodies causes rain in yemen's south and east. rainfall is often in the form of sudden rains, which has a detrimental effect on agricultural land. the mediterranean sea also has an effect on yemen's climatic conditions, as some meteorological fronts, depressions, and air masses cross the northern arabian peninsula from the mediterranean sea. the cold northern air fronts have been left behind; creating an unstable frontal depression that is causing rainfall in yemen's west region and to a lesser degree in the coastal plains. wind speed during winter during the winter, the prevailing winds are the north trade winds and north-eastern winds. the wind speed varies from region to region due to topographical variations, direction, and the constant movement of pressure areas (allaby & garratt, 2007). based on our data (fig. 3) during the summer, the recorded minimum wind speed was 0.4 m/s. during the winter, while raining, a mean wind speed of 0.5 m/s was recorded. during the autumn season, a maximum speed of 7 m/s was recorded. during the winter and spring seasons, the mean wind speed was 2.01 m/s. similarly, during the summer and autumn seasons, the mean wind speeds was within 2.0 m/s and 2.1 m/s, respectively. in the coastal areas, winds were stronger (al hudaydah: 4.9 m/s; al mukalla: 3.8 m/s; and aden: 4.09 m/s). the equability of the surface, the heat disparity between the surface water, and the relatively low atmospheric pressure with land adjacent to it all contribute to this. the winds were strong in sa'dah, al jowf, taiz, and al mahwit, with gusts ranging from 2.1 to 2.9 m/s, medium in dhamar, al kawd, marib, ar riyan, abyan, and al habilayn, (1.5-2 m/s) and weak in the rest of the stations, with gusts ranging from 1.1 to 1.3 m/s. the wind speed with the lowest rate was recorded in alnajob, rad, zabid, lahij, ad dali, and shabwah, which was less than 1 m/s in alfayoush and seiyun. figure 3 shows a graphical representation of wind speed in 28 stations during various seasons. atmospheric pressure and wind during spring between the winter and summer solstices, spring is a transmission season. the weather is influenced by the arabian peninsula's high atmospheric pressure centers, which begin to drop out to the far north, where atmospheric pressure values reach between 1010 and 1012 mbars (allaby & garratt, 2007). the seasonal air depression, which is located/centered on the plateau of the lakes on the african continent, moves towards stations above the eastern regions and north from sudan's center. these changes cause air depressions due to the relatively high temperatures which replace fig. 3 seasonal variations in wind speed in 28 stations at yemen in 2010 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 29 the air heights above the center of the arabian peninsula and north africa. yemen is subjected to different air blocks originating in the north and south while high atmospheric pressure increases in the southern hemisphere. this results in spring air turbulence and rainfall, particularly in yemen's central and southern regions (ibb, al mahwit, hajjah, aden, and al rayyan), which varies year to year. the predominant winds in the country's southern stations are mostly from the south to southeast. in late april and early may, southwest winds are the dominant winds in the north and western stations. in the spring, there is also an increase in rainfall, but only in small amounts for short periods (elzz et al., 1991; algifri, 1998). wind speed during spring several stations, such as hodeidah, al rayyan, mokiras, and habelin, do not experience any changes in wind speed between winter and spring (elzz et al., 1991; algifri, 1998). in contrary, sa’dah, al jowf, ad dali, al mukalla, al kawd, and socotra are among those stations where the wind speed is lower in the spring than in the winter. wind speed increases in the rest of the stations during the winter. during the spring, the highest fast rates are recorded at hajjah and aden stations, ranging from 4.1 to 4.9 m/s, followed by 2.9 to 2.5 m/s at mountain high stations like sanaa, al mahwit, and taiz. the lowest wind speeds, 0.9 m/s, were recorded at the ad dali and alfayoush stations. atmospheric pressure and wind during summer the yemeni seasons are similar to indian seasons, with a low atmospheric pressure of 998 mbar on average and low eastern sudanese atmospheric pressure that affects yemen. south of the equator, there is a high level of atmospheric pressure. as a result, the indian ocean is dominated by hot, humid south-western monsoon winds. summer rains in yemen are caused by the monsoon wind colliding with the mountain slopes. summer is the most popular season in yemen for dust and sand storms, which occur from june to the end of september every year. the strength of the dust and sand storms decreases during the rainy season. rainwater cleans the air by removing dust particles and allowing them to settle. furthermore, rainy years, which are typical in most parts of yemen, hold the soil moist, minimizing soil erosion, which would otherwise be transferred as dust. meanwhile, areas with less rain, especially in the west and south, contribute to the spread of dust, which is then dispersed throughout the atmosphere. atmospheric pressure and wind during autumn the autumn season is a transitional period between the summer and the winter seasons. the depressions above the arabian peninsula and north africa start to deteriorate during this season and are replaced by air blowing in from asia. the atmospheric pressure is between 1012 and 1016 mbar during autumn. meanwhile, the sudanese air depression has influenced the surrounding environment, causing them to settle over the abyssinia plateau and eastern sudan. meanwhile, during the summer in india, the seasonal low atmospheric pressure is dominant. the atmospheric pressure begins to fall to the east and is replaced by high siberian pressure, which begins to spread westward. the northeasterly wind moves to yemen, carrying steady rain until mid-september. at the beginning of october, the northern cold winds approach yemen. yemen is subjected to a combination of northern and southern air currents, resulting in atmospheric pressure centres that are still in the transitional stage. during the autumn, the south air mass brings moisture and travels north, triggering rainfall in yemen's southern regions. wind speed in autumn in most stations, the wind speed is lower in the autumn than in the summer. except for a few stations on the east, west, and southern coasts, it is relatively quiet (elzz et al., 1991; algifri, 1998). al mukalla station has the greatest average speed of 6.2 m/s, followed by hodeidah 4.7 m/s, aden 4.3 m/s, hajjah 3.1 m/s, and al jowf 3.03 m/s respectively. the slowest speed was registered at alfayoush station, which was less than 0.5 m/s. the average wind speed in bayhan, shabwa, and al-dale was 0.7 m/s (fig. 3). seasonal change in temperature dust storms have indirect relationship with temperature. the change in temperature plays a major role in physical and chemical weathering, which aid in the fragmentation and breaking of rocks in their immediate surroundings. rising temperatures and decreasing rainfall cause an increase in the evaporation rate, leading to desiccation in surrounding desert areas. as a long term result, in the republic of yemen's the desert and semi-desert regions are expanding. mountain breezes, valley breezes, land and sea breezes are caused by temperature variations within yemen's topography, during day and night, and between water bodies. these are the result of differences in atmospheric pressure, which cause local winds to form, which contribute to the formation of sand storms and the spread of dust. throughout the year, the temperature in desert and semi-desert areas ranges from 20 to 32°c, with significant differences in monthly and seasonal temperatures between yemen's various regions, reaching up to 40°c in some areas (hoddeidah, aden, hajjah and marib). because of the altitude factor, it decreases slightly in highland areas. during the summer, the minimum temperature was 12.3°c, and during the winter, spring, and autumn seasons, it was 22.4°c, 29.7°c, and 24.2°c. summer temperatures reached 55.2°c, while winter, spring, and autumn temperatures reached 48.2°c, 54.4°c, and 49.9°c, respectively. figure 4 shows a graphical representation of the seasonal variation in temperature at the 28 meteorological stations. seasonal changes in precipitation the seasons of spring and autumn are considered transitional periods between monsoon seasons. since 30 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 1960, the precipitation has been decreasing at a rate of 1.2 mm/month/decade, and this trend is expected to continue (sweeney et al., 2010). during the winter, the lowest amount of rainfall recorded was 0.0 mm, while the highest amount was 330.8 mm. the highest recorded value was 196.4 mm in the summer. figure 5 shows the seasonal variation in monthly precipitation at 28 meteorological stations. statistical analysis descriptive statistics the descriptive statistical results obtained for the wind speed data and t-statistic values are listed in table 1. based on the above data, we can conclude that each season has a significant variation in all variables. because the p-value of all the seasons is greater than 0.05, the t-test data reveals that the group means (wind speed) for all seasons are significantly different at the 0.05 level. there is a significant variation in all variables during each season (table 2). the t-test results show that the group means (temperature) for all seasons are significantly different at the 0.05 level (table 2) because the p-value for all seasons is greater than 0.05. in each season, there are significant variations in all variables (table 3). the t-test results show that the group's means (precipitation) for all seasons differ significantly at the 0.05 level (table 3). the mean value is greater than zero in all three cases, i.e., wind speed, temperature, and precipitation, so we reject the null hypothesis and conclude that the values obtained for all three parameters are significantly different at the 0.05 level, because the p-values for all three seasons are greater than 0.05. oneway anova test the one-way analysis of variance (anova) is used to determine whether the means of three or more independent (unrelated) groups differ statistically significantly. in this study, each of the three parameters/environmental factors is treated as a separate group. all three parameters were subjected to an anova test in this study. table 4 shows the descriptive statistical data obtained for the samples. table 5 shows the results of the one-way anova. we can conclude from the results that the means of all parameters are significantly different at the 0.05 level, rejecting the null hypothesis. the anova test revealed that f (2, 1005) = 301.683, p=0 for the three parameters of wind speed, temperature, and precipitation. the null hypothesis is rejected because the p-value is less than 0.05. since we reject the null hypothesis, we must use/opt for another test, the tukey test and levene's test. fig. 4 seasonal variations in the temperature in 28 stations at yemen in 2010 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 31 fig. 5 seasonal variations in monthly precipitation in 28 stations at yemen in 2010 table 1 the descriptive statistics and t-test results of wind speed seasons # of samples mean stdev sum min med max tstatistic df prob>|t| (p) winter 84 2.016 1.119 169.4 0.5 1.7 6.3 16.510 83 5.94563e-28 spring 84 2.014 1.067 169.2 0.5 1.7 4.8 17.293 83 2.98687e-29 summer 84 2.102 1.253 176.6 0.4 1.75 5.5 15.372 83 5.25922e-26 autumn 84 2 1.354 168 0.5 1.5 7 13.529 83 1.06277e-22 null hypothesis, mean=0; alternative hypothesis, mean <>0; winter at 0.05 levels, the population mean is significantly different from the test mean; spring at 0.05 levels, the population mean is significantly different from the test mean; summer at 0.05 levels, the population mean is significantly different from the test mean; autumn at 0.05 levels, the population mean is significantly different from the test mean table 2 the descriptive statistics and t-test results of temperature seasons # of samples mean stdev sum min med max tstatistic df prob>|t| (p) winter 84 36.541 5.518 3069.45 22.4 38.175 48.25 60.692 83 1.53413e-70 spring 84 43.829 6.096 3681.7 29.7 44.775 54.45 65.888 83 1.92414e-73 summer 84 45.168 7.236 4697.55 12.35 47.525 55.2 63.651 103 1.61097e-84 autumn 84 37.138 6.559 3119.6 24.2 38.675 49.95 51.888 83 4.90731e-65 null hypothesis, mean=0; alternative hypothesis, mean <>0; winter at 0.05 levels, the population mean is significantly different from the test mean; spring at 0.05 levels, the population mean is significantly different from the test mean; summer at 0.05 levels, the population mean is significantly different from the test mean; autumn at 0.05 levels, the population mean is significantly different from the test mean 32 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. table 4 overall descriptive statistics samples # of samples mean stdev se of mean wind speed 336 2.033 1.199 0.06543 temperature 336 40.649 7.478 0.40801 precipitation 336 20.097 34.495 1.8819 table 5 one-way anova/ overall anova sum of squares mean square df f value prob>f (p) model 250866.449 125433.224 2 301.683 0 error 417856.680 415.777 1005 total 668723.129 1007 null hypothesis the means of all level are equal; alternative hypothesis the mean of one or more level are different; at the 0.05 level, the population means are significantly different the quality of linear regression is given in table 6. here, the rsquare or coefficient of determination (cod) value is nearer to/lies between 0 and 1and hence we can say that there is a strong relationship between the parameters analyzed. tukey test and homogeneity of variance test/ levenes test the tukey test compares the means of the three groups to determine which group's mean is different (table 7). it was discovered that the sig value in all three cases is 1. the mean difference is significant at the 0.05 level, as evidenced by this. the homo geneity of variance test was also carried out. table 6 fit statistics r-square coeffvar root mse data mean 0.375 0.974 20.390 20.926 at the 0.05 level, it was discovered that there is a significant difference in variance (table 8). figure 6 shows a graphical representation of the data distribution. wind speed, temperature, and rainfall vary greatly from season to season and month to month (table 9). the day-to-day fluctuations in the variability and differences in the climatic elements have a major impact on dust and sand storms, especially in yemen's desert and semi-desert areas and surrounding areas (akhtar, 2018). correlation test the correlations of climatic variables in all research samples are indicated in table 9. to evaluate the linear relationship between seasonal variables, correlation analyses were conducted. the effects of the seasonal variation of all parameters, including wind speed, temperature, and precipitation, were analysed using correlation analysis. according to the overall statistical findings, there are fourteen positive and ten negative correlations that are significant at the 1 and 5% levels. by comparing the findings, we can see that the parameters have a greater positive correlation and are statistically relevant at the 1% stage. the power of the positive correlation, on the other hand, is weaker (table 9). table 3 the descriptive statistics and t-test results of precipitation seasons # of samples mean stdev sum min med max tstatistic df prob>|t| (p) winter 84 13.728 36.572 1153.21 0 7.2 330.8 3.440 83 9.11391e-4 spring 84 24.269 32.313 2038.62 0 10.35 136.5 6.883 83 1.02907e-9 summer 84 33.046 41.469 2775.9 0 14.15 196.4 7.303 83 1.55517e-10 autumn 84 9.345 18.869 784.98 0 3.25 115.8 4.538 83 1.89283e-5 null hypothesis, mean=0; alternative hypothesis, mean <>0; winter at 0.05 levels, the population mean is significantly different from the test mean; spring at 0.05 levels, the population mean is significantly different from the test mean; summer at 0.05 levels, the population mean is significantly different from the test mean; autumn at 0.05 levels, the population mean is significantly different from the test mean table 7 means comparison / tukey test comparison meandiff sem q-value prob alpha sig lcl ucl temperature / wind speed 38.615 1.573 34.714 0 0.05 1 34.923 42.308 precipitation / wind speed 18.064 1.573 16.238 0 0.05 1 14.371 21.756 precipitation / temperature -20.551 1.573 18.475 0 0.05 1 -24.244 -16.859 sig equals 1, indicates that mean difference is significant at 0.05 level; sig equals 0, indicates that the mean difference is not significant at the 0.05 level table 8 homogeneity of variance test/ levenes test sum of squares mean square df f-value prob>f model 76810.833 38405.416 2 153.977 0 error 250668.914 249.421 1005 at the 0.05 level, the population variance is significantly different. mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 33 fig. 6 graphical representation of data distribution (wind speed, temperature, and precipitation) there are fourteen positive correlations and ten negative correlations in all the studies analyzed since the majority of the correlations between the parameters are statistically insignificant. the most significant positive correlation between variables was found, while the others were all negative. impact of dust and sand storm dust storm and sand storm have both positive and negative effects on the environment. negative impact of dust and sand storms dust and sand storms have impact on the main roads, which are linked to an internal network between the highland, coastal regions and island region. hoddeidah, aden, and hadramout are yemen's most important cities and ports, and they serve as the country's key transportation hubs. yemen and saudi arabia are linked by an international line in this area. furthermore, desert areas are of similar significance in terms of transportation routes. yemen is linked to saudi arabia via the al jowf and marib international lines, while the country is linked to oman via the governorates of shabwah, hadramout, and al mahrah. sands and dust storms minimize the horizontal visibility on these highways, resulting in horrific traffic accidents (notaro et al., 2013). besides, the accumulation of sand on all major roads and sub-roads is a problem, as it triggers the closing of some of them, and drivers who are unaware of the sandstorm's occurrence have their vehicles crash, resulting in major material and human injuries. sandstorms transport sand and dust to agricultural lands, destroying crops, especially those that can't withstand the force of wind or the deposition of sand and dust. meanwhile, farmers are trying to restore agricultural lands that have been buried by sand. year after year, sand and dust storms intensify desertification in arid and semi-arid regions. the storms also transport certain plants and crop diseases from the blown-out areas to the target lands. there have been a few cases when fungi have been transported from the south of saudi arabia to yemen by these storms and have directly affected plants (stefanski & sivakumar, 2009). sand and dust storms cause large-scale economic losses in the short term as well, such as livestock disease leading to death, crop destruction, building and infrastructure damage, and vehicle damage. besides, to clean the accumulated sand and dust, costs a lot of money (sufian et al., 2017). sand storms are having a big effect on yemeni tents. due to war in some areas, such as the aljafnah camp in the marib governorate in august 2018, the majority of people took refuge in tents. these storms have raised their tents. similarly, tents were raised in areas where african refugees fled their countries due to violence and found refuge in un refugee shelters along the coast. owing to the extreme dust storm that passed through those regions, many schools and educational institutions were forced to close. aden city was recently subjected to violent dust storms on september 11, 2019, with winds exceeding 22 km/h and a temperature of 35°c (according to the national center for meteorology and in aden). table 9 correlation of all studied variables during the seasons variables wind temperature rainfall wi sp su au wi sp su au wi sp su au r ai n fa ll au ns ns ns ns ns ns ns ns ns .245* ns su ns ns ns ns -.328** -.395** -.509** -.300** ns .778** sp ns ns ns ns -.381** -.438** -.454** -.266* ns wi ns ns ns ns ns ns -.263* -.288** t em pe ra tu re au ns ns ns ns .683** .657** .733** su ns ns ns ns .666** .720** sp ns ns ns ns .933** wi ns ns ns ns w in d au .800** .802** .665** su .697** .785** sp .858** wi wi = winter, sp = spring, su = summer and au = autumn ** correlation is significant at the 0.01 level (2-tailed). * correlation is significant at the 0.05 level (2-tailed) and ns = non significant 34 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. in the long run, it involves soil degradation, habitat pollution, and desertification, as well as the costs of health care and wasted labor. according to a un (united nations) survey published in 2016, dust storms and the sediments resulting from sand and dust storms cost the arab region's total local production about 13 billion dollars per year. it obstructs irrigation canals and covers drainage routes, causing contamination of river water and streams (prakash et al., 2015; karagulian et al., 2019). dense dust is highly dangerous during aircraft landings and takeoffs, causing landing positions to be changed and takeoff times to be postponed. the engines are damaged by the effect of dust on the aircraft's surface (notaro et al., 2013). solar power plants, particularly those that depend on direct solar radiation, are also influenced by dust. keeping solar collectors clean of dust so that dust particles do not obstruct the incoming radiation which takes time and effort, and is a major source of concern for station operators. positive impact of dust and sand storm the renewal of the soil is a beneficial result of sand and dust storms. during dust storms, loads of dust is transported to the troposphere, from where it is deposited during a calm weather or rain, and falls on the ground in areas hundreds of kilometers away from the dust storm's origin. this dust becomes mixed with the soil and can transfer to sedimentation areas. thousands of tons of new soil are applied annually for agricultural terraces in the bottom and above the surface layer of yemeni land, which are affected by sand storms and dust. dust storms and dust contribute in plant pollination, as well as the movement of certain plant seeds from the source to the destination areas. an investigation found that new plants, which were previously unknown in many areas of yemen, originated in desert and semi-desert areas and were carried by storms. (karagulian et al., 2019). the dust serves as a soil fertilizer and assists in the ripening of fruits. the dust layer that forms above the fruits in yemen aids in their rapid ripening. the dust in the wet ripening of palm products in the tihamah plain helps farmers in that area. instead of using pesticides and industrial fertilizers, farmers in many areas use dust to regenerate fresh leaves and speed up their development. nutrient minerals (e.g. iron) and other elements in the dust are beneficial to land and water ecosystems. hawaii's rain forests get their nutrients from dust brought by the wind from central asia. phytoplankton in the mediterranean sea benefit from metals and nutrients brought by desert winds coming from the north of libya and the sahara dust provides phospholipids additives that offset the loss of the amazon rainforest as a result of river flow. the mediterranean sea's habitats, which form the plankton at the base of its food pyramid, are being threatened by rising drought in the upper soils (forner et al., 2018). the effects of dust on human health the dust storm and dust in air can cause allergy of the eye, of the nose and ear, asthma attacks, dermatitis, and it can negatively influence the condition of people with cardio-vascular diseases. fine dust enters the eye and causes conjunctivitis in the eyelids region, causing redness and itching, as well as tears (world health organization, 2013; aili & oanh, 2015). the small dust particles brought by dust storms (fig. 7) can get into the respiratory system, causing inflammation of the mucous membranes, clogged noses, and respiratory irritation when inhaled. it also induces shortness of breath when exerting physical activity, as well as an itchy nose that can spread to the eyes and ears. they can even make the nose run, in case of increased sensitivity, nosebleeds can appear (ghio et al., 2014; gross et al., 2018). the ear's sensitivity to dust causes inflammation, which causes extreme itching (world health organization, 2013; ghio et al., 2014; aili & oanh, 2015). dust asthma attacks are also common, particularly if the person is exposed to dust because dust can carry bacteria and pollen that cause asthma (world health organization, 2013; ghio et al., 2014; aili & oanh, 2015; gross et al., 2018). when some people inhale dust, it causes skin inflammation, especially eczema, which causes itching (world health world health organization, 2013; ghio et al., 2014; aili & oanh, 2015). chest diseases affect a large percentage of heart patients. because of their susceptibility to dust particles, they suffer from heart muscle inflation and high pulmonary arterial pressure, which contributes to emphysema and capillary breakage (world health organization, 2013; ghio et al., 2014; aili & oanh, 2015; gross et al., 2018). problems faced by the yemen government relating to the dust and sand storms phenomenon the yemeni government is grappling with a slew of issues related to dust and sand storms. the absence of advanced meteorological stations, for precisely monitoring and recording this phenomenon. the shortage of wellequipped laboratories. scientific evidence related to this phenomenon is unavailable due to a lack of financial resources and hence financial support or sufficient funding is very essential. there is a lack of knowledge about environmental initiatives related to this phenomenon and how to deal with it both before and after it happens. there are no short or long-term plans or initiatives in place to mitigate or eliminate the risk associated with this phenomenon that exists across wide areas of yemen. if the yemeni government can update and fix all of the above-mentioned problems, we can at least reduce the potential impact of the dust storm and sand storm in yemen. mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. 35 conclusion yemen is affected by dust all over year, although it is less prevalent in the winter and more prevalent in the summer, although it is unpredictable in the spring and autumn due to the general weather condition. coastal areas (hajjah, hoddeidah, taiz, lahg, aden, abyan, shabwah, and hadramout) and desert areas (marib and al jowf) are the most affected by dust and sandstorms during the year, while the western and central governorates of yemen in the mountainous region are predominantly affected by dust over the winter. wind speeds in coastal areas such as al hudaydah (4.9 m/s), al mukalla (3.8 m/s), and aden (4.09 m/s) rise in intensity. the equability of the surface, the contrast heat between the surface water, the relatively low air pressure, and land adjacent to it all contribute to the change in wind speed. yemen is subjected to different air blocks, originating in the north and south, forming spring, air turbulence, and rainfall, particularly in the central and southern areas, as atmospheric pressure rises in the southern hemisphere. in between summer season, rain continues to fall until mid-september, as the result of the return of the northeast storms. different atmospheric pressures generate different forms of wind, including sea and land breezes, mountain and valley breezes, fohen, al ghawbah, and warm (al-kawi) winds. the presented research shows that environmental factors play an important role in the creation of dust and sand storms. according to the statistical analysis, environmental parameters are significantly correlated with one another, resulting in the development of dust and sand storms. dust storms in yemen have several effects on humans, animals, plants, and all-natural habitats, and they can be categorized as both positive and negative based on their impact on environmental components. fig. 7 heavy dust storms crossing some of the yemeni cities (source: yiannopoulos, 2018) 36 mokbel et al. 2021 / journal of environmental geography 14 (1–2), 24–37. acknowledgement the authors of this article wish to acknowledge nasa for the satellite image, and 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kiss and andrási, 2011; cheng et al., 2012) and morphology too (bonacci and oskoruš, 2008; williams and wolman, 1984; kiss and blanka, 2012; kiss and andrási, 2015). for the society the most important changes are the frequency increase of floods and the decreasing level and increasing durability of low water stages. as a result of lower water stages, the water extraction (for drinking, irrigation or industrial cooling) will be more and more difficult, and the shallow riverbed deteriorates shipping and the incision might ca use damages for floodplain ecosystems (kiss and andrási , 2015). in the carpathian basin several rivers are affected by similar hydrological changes. for example on the dráva river the level of low stages decreased by 118 cm in connection with dam construct ions during the last century, resulting in channel pattern changes (kiss and andrási, 2011; kiss and balogh, 2015). on the maros river water stages decreased by 50 cm in the past 20-30 years (sipos, 2006), whilst on the hernád by 60 cm in the last 50 years (blanka, 2010), both resulting in channel narrowing. the danube is one of the most important commercial waterways in central europe. however, shipping requires significant regulation works, such as construction of revetments and groynes, which alter natural processes in river morphology. the changing hydrology (characteristically decreasing stages) is also the result of cut-offs of meanders in the 19th c., and gravel mining started in the 1970’s (vituki, 2007). one of their consequences is that meander development terminates (somogyi, 2001) and the low water stages start to decrease gradually, while the frequency of record-high floods increases (vituki, 2007). besides several dams trap sediment and affect the hydrology (idcpr, 2014). the second largest danubian dam located at bős– gabcikovo (its hydropower plant operates since 1992) is responsible for higher durability of low stages and incision by ca. 1.5 m on the downstream sections of the river (rákóczi, 2000; vituki, 2007). due to the incision, the lowest navigable water level had to be set at lower and lower water stages, thus it was decreased by 0.9 m between 1970 and 2004. as a result, on the hungarian–croatian section riffles and fords inhibit shipping during low-stage periods. nowadays, a current topic in the hungarian news is the planned expansion of the paks nuclear power plant, which needs increased cooling water supply, which could only be provided by damming the river downstream of paks [1]. no preliminary impact study has been made on the possible consequences on river morphology, water regime or sediment-transport yet, nor is the present channel processes known in detail. 2 nagy and kiss (2016) the aim of the present research is to reveal the longterm changes in hydrology of the danube, and in connection with them to analyze the morphological changes of the riverbed, focusing on the development of mid-channel bars and islands study area on the danube regulation works started at the end of 19th century. their main objective was to shorten flood-waves and increase their velocity, therefore several meanders were cut-off downstream of budapest. one of the sharpest and thus most dangerous bend located near bogyiszló, which played an important role in ice damming, for example during the devastating icy flood in 1838. between dunaföldvár and the hungarian–croatian border altogether 32 meanders were cut off, and the channel was almost straightened. the final step of regulation works was the construction of groynes to support shipping (ihrig, 1973). in the 1970’s in-channel gravel mining started causing intensive incision and low stages decrease, thus shipping became more difficult. the incision made the water withdrawal complicated, especially for the paks nuclear power plant, therefore the rate of dredging was reduced. however, the increasing duration of low water stages is still a problem, in connection with the bős– gabcikovo dam (vituki, 2007). in the present study the water stages measured at mohács gauging station (1446.9 fkm) were analyzed and the morphological changes of a downstream section of the danube near bogyiszló (1493–1502 fkm) (fig. 1). in this section the river has 4-5 cm/km gradient, and the channel width varies between 450 m and 600 m. the transported sediment is very fine-grained, especially made up of fine silt and sand (vituki, 2007). the studied nearly straight section was formed when the meander at bogyiszló was cut off in 1856 to avoid the development of ice-jams (ihrig, 1973). along the studied section the channel development is mainly affected by groynes built since 1935 (ihrig, 1973), though the main period of groynes construction was in the beginning of the 1950’s. fig. 1 hydrological data are from mohács gauging station, whilst the studied channel section of the danube is located north of mohács. (source: google earth) methods daily water stages (1890–2013) and discharge values (1900–2013) measured at mohács gauging station were analyzed (data source: aduvizig). this huge dataset has been divided into ten-year periods (1900-1909, 19101919 etc.) to facilitate analysis. in each period we calculated the duration of different stages, the number of days when low stages (≤315 cm, occurred with a frequency of 90% in the first decade) were present, and we analyzed the water stage – discharge relationship. we analyzed the development of the river channel near bogyiszló using maps and aerial photographs representing the period between 1952 and 2014. the maps and aerial photos were geo-referenced, and we digitized the banklines, and bars with and without woody vegetation using arcgis. results hydrological changes of the danube river at mohács the stage duration curves of the decades show obvious decrease of water stages lower than 700 cm (fig. 2). in the first decade (1900-1909), for instance water stages were above 315 cm during 90 % of the period, though in the last ten years (2000-2009) they were above 179 cm in accordingly, referring to a decrease of 136 cm at 90 % frequency stages. fig. 2 changes in the duration of water stages obvious change in the duration of flood stages cannot be proved, however their extremity (scattering) decreased, thus record-high flood stages (>900 cm) became more frequent since the mid-20th century (fig. 3). between 1900 and 1946 annual highest stages were more or less similar characterized by some fluctuations. in this period characteristically the annual flood stages were between 700 cm and 850 cm, and flood level exceeded 900 cm only once (in 1938). however, in the second half of the 20 th c. and especially in the 21st c. quite high flood stages occurred, when flood stages exceeded 900 cm more often (in 1954, 1956, 1965, 1975, 2002, 2006, 2010 and 2013). this does not obviously mean that the height of flood stages continuously rises, just their frequency increases. hydrological and morphological changes of the lower danube near mohács, hungary 3 fig. 3 changes in the annual flood stages (1900–2013) at mohács gauging station annual low water stages decreased significantly during the studied period (fig. 4). in the first half of the 20th century (1900-1945) the level of the annual lowest stages exceeded 200 cm, their average height was 245 cm. extremely high stages occurred in 1910–1916 and 1936– 1941 when most of the water stages were above 315 cm. in the second half of the studied period (1946-2013) the level of annual low water stages decreased, thus between 1946 and 2002 their average height dropped by 84 cm to 170 cm, and since 2003 their average height decreased further to 125 cm. these results show an obvious decrease of low water stages, which could be explained by (i) more extreme water regime or (ii) by incision of the riverbed. fig.4 level of the annual lowest water stages (1900–2013) at mohács. the red lines represent average values of different periods the extremity of water regime could be proved by changes in the number of days when low water stages (≤315 cm) occurred. the duration of low stages within the decades increased considerably (fig. 5). in the first decades of the 20th century low stages occurred in 7-15 % of the decades, however from 1990 until 2013 it increased to 43-47 %, thus the duration of low stages increased by five times (by 20 day/year). this process is in connection with the operation of bős–gabcikovo hydroelectric power plant, which started to function in 1992, or it could also be connected to the incision of the riverbed due to groynes built in the river. riverbed incision could be indicated by the changes of water stage – discharge (h–q) relationship: discharge appertaining to a given water level increases in the case of incision, while it decreases in the case of aggradation. however, if the height of flood stages increase while discharges stay stable or decrease, it means that flood channel becomes narrower (vágás, 2004). the h–q point-clouds gradually shift upwards (fig. 6), i.e. discharges appertaining to given water stages increase considerably. it obviously refers to the incision of the riverbed. discharges appertaining to low water stages are gradually increasing, for example, discharges belonging to 250-300 cm water stages increased from 900950 m3/s to 1700 m3/s in the last almost 110 years. this obviously proves the incision of the riverbed, as the channel transports almost twice as much water at the same water stage. in the case of higher water stages, there is no significant increase or decrease in the relationship between water stages and discharges. however, the frequency of record-high flood stages shows an increasing trend. the increasing water stages at same discharges can be caused by the narrower flood channel. fig. 5 duration of low water stages (≤315 cm) at mohács gauging station fig. 6 relationship between water stages and discharges measured at mohács horizontal changes in the channel of the danube near bogyiszló in the first analysed year (1952) there were only two bars (area: 0.046 km2) which developed behind groynes, downstream of the mouth of a tributary (sió river, at 1496 fkm; fig. 7). in the following year (1953) more bars formed behind the newly built groynes. at the 1500 fkm 4 nagy and kiss (2016) a large bar evolved (area: 0.22 km2) with some herbaceous vegetation. the area of already existing bars increased (to 0.88 km2), and by now their surface was covered by woody vegetation. in the bend, in the southernmost part of the study area (1493 fkm) new sand bars formed without vegetation. the location and area of bars changed considerably until 2000 (fig. 8). along the uppermost section (1498–1502 fkm) islands developed behind each groynes, and they were already completely colonized by forests. in the bend along the southern section of the study area, the inlet of an oxbow lake became closed by a sediment plug and a small island became connected to the riverbank. besides three more bars were formed, one of them was covered by herbaceous. in this year the total area of the bars and island was 0.4 km2. by 2011 the area of bars and islands doubled (0.85 km2) and they became common along the whole studied reach. it could be explained by the increasing duration of fig.7 location of bars (1953) in the studied section of the danube near bogyiszló fig.8 location of bars and islands in the study area in 2000 (a) and in 2014 (b) hydrological and morphological changes of the lower danube near mohács, hungary 5 low stages, the drop of their level, and the lack of significant flood which could have eroded the material of the islands and bars. the most intensive aggradation was typical in the bend at the downstream section of the study area, as here the area of islands and bars increased from 0.13 km2 to 0.29 km2 within one year. on the last aerial photo (2014) the morphology of the reach remained the same as it was in 2011 (fig. 9). the total area of bars and island increased by 0.04 km2 and the area of woody vegetation increased on the islands north of 1498 fkm. the number of bars decreased though their total area increased, probably because the bars coalesced and the water level decreased at the time of the shots of the aerial photographs (2011: 72 cm, 2014: 36 cm). fig. 9 changes in total area and vegetation cover of the studied section of the danube between 1952 and 2014 reviewing the processes it could be stated that in the northern section of the study area (upstream of 1498 fkm) bars and islands are spatially permanent features, and they have not changed significantly since their formation. in contrary, in the southern, downstream section they are more changeable, as their material could be eroded and transported away easily during floods, and they could coalesce during low water stages. the more dynamic formation and development of these forms could be the resulted of the closeness of the thalweg. between 1990 and 2000 the number of bars doubled (from 4 to 10), due to the increased duration and frequency of low water stages and the descending water level. in the first decade of the 21 st c. the number and size of wooded islands increased, while the area of bare and herb vegetated bar surfaces fluctuated (fig. 9). this could only be explained by the changes in water stages, as due to descending water stages the higher surfaces of bars become watertight, thus vegetation could colonize them, while lower bars still have bare surfaces, as they are in the zone of fluctuating water level, thus they develop more dynamically as their material could be transported away by smaller flood waves. as a result of bar formation the width of the channel decreased considerably. while in the 1950’s the average channel width was 600 m, in 2014 it became 480 m. the most significant narrowing took place at 1500 fkm, where the width of the channel decreased from 780 m to 445 m. conclusions at the lower section of the hungarian danube the height of low stages decreased by 136 cm (1.2 cm/y) during the analyzed period (1900–2013). the duration and frequency of low stages increased, and their level decreased, thus for example between 1900 and 1909 water stages exceeded 315 cm in 90 % of the decade, whilst between 2000 and 2013 they only exceeded 179 cm accordingly. on the other hand, the height of yearly highest (flood) stages became more scattered, and the frequency of record-high flood stages increased. the analysis of the relationship between water level and discharge values refers to significant changes in water regime and in river channel. simultaneously with the water level drop, the number of bars quadrupled in the analyzed section of the danube between 1952 and 2000. this process became accelerated in the 1990’s, when low water stages (≤315 cm) were measured almost in half (43 %) of the decade, while in the 1980’s they occurred only in 33 % of the decade. as a result, sediment accumulation began behind the groynes, and woody vegetation could colonize the surface stabilizing the material of bars. the duration of low stages continued to increase (48%) in the 2000’s, thus the number and area of bars continued to raise and woody vegetation could spread on their surface. development of bars has feedback on water stages and on the development of the river channel, as due to bars the river channel becomes narrower, which affects the height of flood stages and results in intensive riverbed incision. in the study area the average width of the channel decreased from 600 m to 480 m, though at some places it became narrower by 330 m (by 45%). these changes affect shipping, as due to riverbed incision and decrease of low water stages, lowest shipping water levels have to be stated at lower and lower water stages. on the other hand, drop of characteristic water stages affect water management, as water extraction will face difficulties, thus irrigation and industrial cooling water supply will be limited in the future. acknowledgements the research was funded by támop-4.2.1.d15/1/konv-2015-0002, husrb/1203/121/130 and nkfih k-119193 projects. references blanka, v. 2010. kanyarulatfejlődés dinamikájának vizsgálata természeti és antropogén hatások tükrében. phd thesis, 50–60. (in hungarian) bonacci, o., oskoruš, d. 2008. the influence of three croatian hydroelectric power plants operation on the river drava hydrological and sediment regime. 24th conf. of the danubian countries, 11p. geng, q., hui, x., hu, g.x., hui, z.y. 2012. the change and effect factors of water level in jingjiang river, int. conf. on modern hydraulic engineering 28, 165–170. icpdr, 2014. hydropower plants in the danube river basin online at: https://www.icpdr.org/main/sites/default/files/nodes/documents/map_hydropower_june_2014.pdf ihrig, d. 1973. a magyar vízszabályozás története, ovh, budapest (in hungarian) 6 nagy and kiss (2016) kiss, t., andrási, g. 2011. a horvátországi duzzasztógátak hatása a dráva vízjárására és a fenékhordalék szemcseösszetételének alakulására. hidrológiai közlöny 91 (5), 17–29. (in hungarian) kiss, t., blanka, v. 2012. river channel response to climateand human-induced hydrological changes: case study on the meandering hernád river, hungary. geomorphology 175, 115– 125. doi: 10.1016/j.geomorph.2012.07.003 kiss, t., andrási, g. 2011. a horvátországi duzzasztógátak hatása a dráva vízjárására és a fenékhordalék szemcseösszetételének alakulására. hidrológiai közlöny 91 (5), 17–23. (in hungarian) kiss, t., andrási, g. 2015. a dráva menti ártéri élőhelyek átalakulása. in: rakonczai, j., blanka, v., ladányi, zs. (eds): tovább egy zöldebb úton. szte-tfgt, szeged, 164–173. (in hungarian) kiss, t., andrási, g. 2015. kanyarulatfejlődés sajátosságai és antropogén hatások vizsgálata két drávai kanyarulat példáján. tájökológiai lapok 13 (1), 73–88. (in hungarian) kiss, t., balogh, m., 2015. characteristics of point-bar development under the influence of a dam: case study on the dráva river at sigetec, croatia. journal of environmental geography 8 (1–2), 23–30. doi: 10.1515/jengeo-2015-0003 kiss, t., sipos, gy., fiala, k. 2011. az alföld töltések közé szorított folyói. in: rakonczai, j (ed): környezeti változások és az alföld. a nagyalföld alapítvány kötetei 7, békéscsaba, 211–222. (in hungarian) rákóczi, l. 2000. a duna-meder sorsa szap és szob között. vízügyi közlemények 82 (2), 262–284. (in hungarian) sipos, gy. 2006. a meder dinamikájának vizsgálata a maros magyarországi szakaszán. szte-tfgt, phd thesis, 21–54. (in hungarian) somogyi, s. 2001. természeti és társadalmi hatások a duna mai vízrendszerében. földrajzi értesítő 50 (1-4), 299–309. (in hungarian) vituki, 2007. a duna hajózhatóságának javítása tárgyú projektet megalapozó tanulmány. budapest, 29–97. (in hungarian) williams, g.p., wolman, m.g. 1984. downstream effects of dams on alluvial rivers. usgs prof. paper 1286 internet references: [1] http://nepszava.hu/cikk/1015462-lmp-a-duna-duzzasztasaval-jarhatpaks-bovitese journal of environmental geography journal of environmental geography 7 (3–4), 1–12. doi: 10.2478/jengeo-2014-0007 issn: 2060-467x preliminary contamination risk assessment of mining waste using spatial analysis and geochemical characterization of rock formations. case study in hungary ahmed abdelaal department of geology, south valley university, 83523 qena, egypt *corresponding author, e-mail:ak_elmalt@yahoo.com research article, received 10 february 2014, accepted 01 april 2014 abstract the mine waste directive (2006/21/ec) requires the risk-based inventory of all mine waste sites in europe. the geochemical documentation concerning inert classification and ranking of the mine wastes requires specific field study and laboratory testing and analyses of waste material to assess the acid mine drainage potential and toxic element mobility. the procedure applied in this study used a multi-level decision support scheme for the inert classification of waste rock material including: 1) expert judgment, 2) data review, 3) representative field sampling and laboratory analysis and testing of rock formations listed in the national inert mining waste list, and 4) requesting available laboratory analysis data from selected operating mines. based on a preliminary expert judgment, the listed formations were classified into three categories. a: inert b: probably inert, but has to be checked, c: probably not inert, has to be examined. this paper discusses the heavy metal contamination risk assessment (ra) in the hungarian quarrymine waste sites. in total 30 waste sites (including both abandoned mines and active quarries) were selected for scientific testing using the eu pre-selection protocol. altogether 93 field samples were collected from the waste sites including andesite, rhyolite, coal (lignite and black coals), peat, alginite, bauxite, clay and limestone. laboratory analyses of the total toxic element content (aqua regia extraction), the mobile toxic element content (deionized water leaching) carried out according to the hungarian gkm decree no. 14/2008. (iv.3) concerning mining waste management. a detailed geochemical study together with spatial analysis and gis were performed to derive a geochemically sound contamination ra of the mine waste sites. key parameters such as heavy metals, in addition to the landscape metric parameter such as the distance to the nearest surface and ground water bodies, or to sensitive receptors such as settlements and protected areas calculated and statistically evaluated in order to calibrate the ra methods. results show that some of the waste rock materials, assumed to be inert, were found non-inert. thus, regional ra needs more spatial and petrological examination with special care to rock and mineral deposit genetics. keywords: risk assessment, pre-selection, rock formations, spatial analysis, geochemistry, inert, mining waste introduction mining has severe impacts on the environment, including contamination by toxic metals. in this context, europewide survey identified wide-spread pollution problems caused by mining, abandoned mines in particular (com, 2003). since most of the elements used by the society come from mineral extraction (76 out of 90 frequently used elements), mining of mineral resources provide essential raw material for economic development (com, 2005). abandoned mines are more of a problem in areas with long historic mining like europe, because mine closure practices have changed with time and environmental protection has not been considered for closed mines until recently (jordan, 2004; navarro et al., 2008). apart from that abandoned mines are the same as active mines in terms of types of hazard and potential impact on the environment, their major problems are uncertainty in information and lack of control. direct exposure to acid mine drainage (amd) and sediments discharged from abandoned metal mines poses a serious hazard to aquatic biota and to humans (peplow and edmonds, 2005; panagopoulos et al., 2009; lei et al., 2010; sarmiento et al., 2011). younger et al. (2002) estimated that about 1,000 to 1,500 km of watercourses are polluted by metal mine discharges in the eu (estimate is for the former eu 15). there are an estimated 3 million potentially contaminated sites in the whole european union, of which about 250,000 are actually contaminated and in need of remediation (eea, 2007). due to great volumes and slow chemical processes, mineralised rock in mine workings and in mine waste can release toxic compounds for a very long time on the scale of centuries and thousands of years (bat, 2003). thus, remediation of mine sites, including abandoned mines, has to consider long-term solutions and remediation technologies have to be sustainable for a long time (sinding, 1999; panagopoulos et al., 2009). around the mine site, soils and surface water in the receiving environment are often contaminated with harmful elements or compounds (puura et al., 2002; sarmiento et al., 2011). these contaminated sites act as secondary sources for pollution, especially for historic sites (jordan and d’alessandro, 2004). 2 abdelaal (2014) significance of contamination risk posed by mining is highlighted by mine accidents (jordan and d’alessandro, 2004). examples of such accidents are wales, uk, in 1966, stava, italy, in1985, aznalcollar, spain, in 1998, baia mare, romania, in 2000 and most recently the catastrophic release of 850 million cubic meters of alkaline (ph >13) caustic red mud through the failed dam of the ajka alumina plant depository on october 4, 2010 in kolontar, hungary, resulting in loss of lives and contamination of agricultural lands (jordan et al., 2011). limited financial resources restrict remediation of sites at regional scale, therefore, there is a strong need to develop methodologies that rank sites based on risk magnitude, rather than to produce absolute estimates of health/ecological impacts, or to prioritize the remediation actions (long and fischhoff, 2000; marcomini et al., 2009). u.s. epa (2001) gives a detailed description of risk-based assessment of mine sites. the effort required to identify and prioritize contaminated sites in europe is considerable (eea, 2005). moreover, as for the prioritization process, the soil thematic strategy for soil protection (com, 2006) and the eu mine waste directive (2006/21/ec), point out the need to develop spatial riskbased methodologies for sustainable management of contaminated sites and mining waste sites at regional scale. the eu mwd pre-selection protocol (stanley et al., 2011) is applied for contamination risk assessment of mine waste sites (abdaal et al., 2013). the protocol has a ‘yes-or-no’ questionnaire and consists of 18 questions using simple criteria available in existing databases readily enabling the preliminary screening of the mine waste sites for environmental risk (fig. 1). this screening should result in the elimination of those sites which do not cause or have the potential to cause a serious threat to human health and the environment from the inventory of waste sites. since the pre-selection protocol meant not to involve field sampling or laboratory analysis, any level will be sufficient to pass the test and select the site for further investigation as a precautionary measure. in case of lack of knowledge or information, i.e. in the presence of uncertainty, an ‘unknown’ response is entered for the particular parameter which is the same as a yes response and the site is selected for further examination which is a precautionary position. in this study the mine waste sites included inside the rock formations and delineated as polygons’ maps. the geochemical documentation concerning inert classification and ranking of the wastes listed in the inert mining waste list of the hungarian office of mining and geology involves the following procedures: 1) expert judgment, 2) data review, 3) representative field sampling and laboratory analysis of formations listed in the inert mining waste list, and 4) requesting available laboratory analysis data from selected operating mines. based on a preliminary expert judgment the listed formations classified into three categories. a: inert b: probably inert, but has to be checked c: probably not inert, has to be examined (table 1). according to the hungarian gkm decree no. 14/2008 (iv.3) the mining waste classified to inert as if the content of substances potentially harmful to the environment or human health in the waste and in particular as, cd, co, cr, cu, hg, mo, ni, pb, v and zn, including in any fine particles alone in the waste, is sufficiently low to be insignificant human and ecological risk, in both the short and long term, in order to be considered as sufficiently low to be of insignificant human and ecological risk, the content of these substances shall not exceed the thresholds values for geological medium and underground waters identified as not contaminated in relevant legal rules. table 1 the inert-not inert classification of the listed rock formations based on preliminary expert judgment. a: inert b: probably inert, but has to be checked c: probably not inert, has to be examined. number of waste sites and field samples for each rock group are shown. rock group rock type number of waste sites number of samples inert not inert ranking coal lignite 2 10 c black coal 2 7 c peat 4 9 c alginite 2 5 b bauxite 2 6 b rhyolite tuffs 2 6 b clay clay 4 8 a-b bentonite clay 1 1 a andesite 10 37 b limestone 1 4 a a detailed geochemical study together with spatial analysis and gis performed to derive a geochemically sound contamination ra of the mine waste sites in order to identify the current geochemical status of sampled rock materials from the 30 mine waste sites and to answer the question, if these waste rock materials (i.e. coal, peat, alginate, bauxite etc.) are still inert or non-inert. distribution analysis applied to the median values of the elements as, cd, co, cr, cu, mo, ni, pb, and zn contents in order to find if there are any significant correlations between these elements to each other and to be compared to the local (country-specific) thresholds values for geological medium and underground waters in hungary, in addition to the environmental limit values in europe. the key landscape parameter, the distance from the waste sites (as centroid point of the formation polygon) to the nearest surface and ground water bodies, or to sensitive receptors (such as settlements and protected areas) was statistically calculated in order to evaluate the ra method (mwd pre-selection protocol, fig. 1) and to identify local thresholds (median-based values of the measured distances from waste sites to the nearest pathways and sensitive receptors) more adopted the local conditions in hungary. the objective of this paper is to perform a preselection ra for selected rock types using the geological map of hungary as polygons, to evaluate the eu mwd pre-selection protocol (stanley et al., 2011, fig. 1) by applying it to real-life cases of 34 mines waste sites in hungary. three tests are carried out. preliminary contamination risk assessment of mining waste … 3 first, a detailed statistical and landscape metric analyses are carried out for the protocol threshold values (e.g. stream line density inside the polygons, number of patches (settlement, lake, natura 2000 sites and agricultural areas inside each polygon) and counting the polygon overlap areas between natura 2000 sites and the rock formation polygons. second, altogether 93 field samples of different rock types, collected from the waste sites, were an alysed for the total toxic element content (aqua regia extraction), the mobile toxic element content (deio nized water leaching) on the base of hungarian gkm decree no. 14/2008. (iv.3) concerning mining waste management. this detailed geochemical study t ogether with spatial analysis and gis were performed to derive a geochemically sound contamination ra of the mine waste sites. third, a, b and c inert ranking system based on the expert judgment, has been applied for the rock types in the waste sites, which were compared to a simple risk-based ranking of the mine waste sites based on the specific geochemical analysis results of the waste samples. study area altogether 30 waste sites of both abandoned mines and active quarries have been selected for scientific testing using the eu mwd pre-selection protocol (fig. 2). 93 field samples have been collected from the waste sites including different rock samples such as; andesite, rhyolite tuffs, coal (lignite and black coals), peat, alginite, bauxite, clay and limestone according to the eurogeosurveys geochemistry expert group sampling protocol (fig. 3). various wall rock and waste heap samples were collected for a detailed geochemical characterization. fig. 1 the eu mwd pre-selection protocol flowchart (stanley et al. 2011) 4 abdelaal (2014) the alginite mined in pula site (nw hungary, fig. 2) originated from biomass of fossil algae during several millions of years in volcanic craters. its organic material content is about 5-50% (szabo, 2004). gömöryová et al. (2009) reported that tests of alginite from the deposits in pula and gerce showed that it can be used in agriculture and forestry to improve soil quality, soil water dynamics and nutrient content, to increase organic matter content, colloid content and to protect soil against acidification, desiccation and leakage of nutrients (vass et al., 2003). in the power generation sector, coal is playing a dominant role in the eu with 25% share of the total installed capacity and almost one-third of the power generation (kavouridis and koukouzas, 2008). coal resources in hungary are in total 3,300 million tons (mt) with annual production between 9-10 mt (of which 8 mt is lignite) (perger, 2009). at this rate of use the reserves could last for centuries. three types of coal in hungary were sampled: 1) black coal in southern mecsek mountains (lower jurassiclias) is hungary’s only black coal reserve, calculated to be 198.8 mt. due to the complicated geological circumstances and the high cost of exploitation, production was stopped in 2004. 2) brown coal was widely mined throughout recent decades through the transdanubian mountains with good quality eocene and oligocene coal, supplying a significant amount of hungary’s energy needs. mining has virtually stopped due to economic reasons, with remaining reserves calculated to be 170 mt. there is only one mine operating and supplying the vértes power plant. cretaceous coal exploitation in the region ended in 2004, after resources ran out. poor quality miocene reserves can be found in northern hungary. while all underground mining were ceased, small open-pit mines are still operating and exploitation can be extended. 3) lignite represents about 90% of the hungarian coal reserves, which means that lignite is first on the hungarian conventional energy sources. while some miocene lignite reserves ran out in the transdanubian mountains in 1996, about 3000 mt of miocene-pliocene lignite can be found in visonta, bükkábrány (northern hungary) and torony (western hungary) (fig. 2). recently, the visonta and bükkábrány sites were subject to vast open-pit mining supplying the mátra power plant, while the torony site remains practically untouched by any mining activity (hamor-vido, 2004). peat was used as a fuel from early times in europe. it was exploited intensively in agriculture and currently there is a renewed interest in the material because of its potential as a general source of hydrocarbons and other more particular organic raw materials used industrially. peat was invariably found with significant moisture content at the surface of the ground, within a depth of 2-15m (spedding, 1988). number of significant articles were published on different aspects of peat and its use (e.g. del-rio et al., 1992; steinmann and shotyk, 1997; charman, 2002). fig.2 examples of rock formations (as polygons) and locations of field sampling from abandoned mines and active quarries in hungary. a) pula alginite formation, b) gant bauxite formation, c) lignite formation at visonta, d) andesite formation in the tokajmts., e) peat formation at pölöske, f) clay formation at maza preliminary contamination risk assessment of mining waste … 5 fig.3 field sampling for the eu mine waste directive inert waste testing and characterization in hungary 1a and b. alginite sampling in pulla; 2a and b. bauxite sampling in gant; 3a and b. lignite sampling in visonta; 4a and b. andesite sampling in tokaj. see fig.1 for sampling locations materials and methods sampling this study used a multi-level decision support scheme including a representative field sampling and laboratory analysis of formations listed in the inert mining waste list and requesting available laboratory anal ysis data from selected operating mines. altogether 93 samples have been collected according to the eurog eosurveys geochemistry expert group sampling protocol from 30 mine-quarry waste sites along hungary (fig. 2). rock types and locations of samples are as follow: coal (10 lignite samples from visonta and bükkábrány sites and 7 black coal samples from pécs vasas mine sites); 9 peat samples from pölöske, hahót and alsopatak sites; 5 alginite samples from pula and gérce sites; 6 bauxite samples from gánt site; 8 clay samples from máza, miskolc and vác sites and one bentonite clay sample from mád site; 37 a ndesite samples from recsk, tokaj, komló, t állya, sárospatak and tarcal mine sites; 6 rhyolite tuffs samples from gyöngyöslymos and felsoabasár sites and 4 limestone samples from vác mine site (fig. 2, table 1). selection of the samples at the site depends on the location of each sample, (e.g. lignite includes wall, overburden and waste samples), and on the rock type (mineral composition), (e.g. oxi-andesite and pyrite andesite samples were collected). the collected two kilograms of samples were always composed of three sub-samples located at a minimum of 10m distance and at any sudden change in the color of waste rock, a new sample was collected (fig. 3). laboratory analysis laboratory analysis of the collected 93 field samples is carried out for the total toxic element content (aqua regia extraction) and the mobile toxic element content (deionized water leaching) at the geological and geophysical institute of hungary (mfgi) and 70 samples were selected for the analysis of different forms of sulfur (sulfuric acid potential) are carried on the isd dunaferr laboratory at dunaujvaros on the base of hungarian gkm decree no. 14/2008. (iv.3) concerning mining waste management. samples were analyzed for total toxic element content (aqua regia extraction), the mobile toxic element content (deionized water leaching) with icpoes. samples were air-dried, crushed in an agate mortar, passed through disposable sieve of 100 mesh, and digested by aqua regia with hno3, hcl and h2o2 under the iso 11466 procedure (international organization for standardization 1995). all materials used during analytical determinations were kept in teflon or other metal-free containers. to check the quality of preparation and analysis, replicate determinations were performed on approximately 25% of samples. total element content of as, cd, co, cr, cu, mo, ni, pb, v and zn was defined by a mixed acid microwave unit digestion while deionized water leaching (ph=7) was performed to estimate the mobility of toxic elements in relative percent of total concentration. spatial data two types of data were used in this study. waste site data includes (1) location of mines waste sites as polygons (fig. 2), (2) composition of the mine waste including sulphides, toxic metals, and dangerous processing substances (q2-q3), (3) geometry of the waste site area (q8) and slope of foundation (q10), and (4) other data such as presence of impermeable layer beneath the waste site (q12), and if the site is uncovered and thus the waste is exposed to wind or direct contact (q13-q14). information on the mine waste site engineering design was obtained from mine archives, aerial photos and field studies. spatial data include topographic data of location of settlements as polygons, surface water courses (streams and lakes). slope data calculated from the hungarian national contour based military ddm 50m grid using arcgis 10 ® software (fig. 4). then polygons of the rock formations added as overlay layer to the slope map in raster format using spatial analysis tool in arcgis 10 ® . the slope value for each rock formation polygon (in degrees) 6 abdelaal (2014) was counted as an average value from all pixels inside the polygon. census data for 2009 is available from the hungarian central statistical office. data on the national protected areas (natura 2000 sites) and the location and status classification of groundwater bodies in hungary under the water framework directive (wfd) were obtained from the hungarian central directorate of water and environment (vkki) and from eea website (waterbase-groundwater datasets). land use/land cover data (lulc) maps at 1:100,000 scale were obtained from the european corine land cover website. fig.4 calculation of the topographic slope for the sampled rock formations (as polygons) using the national contour-based spline-interpolated military 50m grid dem. the same dem is used for question q10 of the eu pre-selection protocol on the topographic slope below the mine waste site. polygon highlighted is this example delineates the gant bauxite formation including bauxite samples from gant bauxite mine in order to identify if there is a high permeable layer beneath the mine waste site (q12), a surface permeability map for the geological formations of the 1:100,000 surface geological map of hungary has been constructed using arcinfo ® 10, on the basis of the physical and geochemical characteristics of the uppermost rock units. three classes were distinguished (fig. 5). lowpermeability formations (clay and other impermeable rocks), formations with medium-permeability (loess, sandgravel and fractured metamorphic and volcanic rocks) and with high-permeability (karstified limestones and dolomites belong to this group). an example for the high permeability rock class is the alginite formation in gérce mining area, nw hungary (fig.5). polygons of the mines waste sites derived from the corine land cover 1:50,000 map (2000) were overlaid by google earth ® aerial photographs (2013), in order to identify if the material within the mine waste sites is exposed to wind or not (q13) or covered or not (q14), (fig. 6). fig.5 surface permeability map developed to answer question q12 of the eu mwd pre-selection protocol if there is a high permeable layer beneath the mine waste site. ploygon highlighted is an example for the alginite formation at the gérce mining area, nw hungary. see text for details. fig.6 polygons of the mine waste sites defined from the corine land cover map (clc 2000) overlaid by google earth ® aerial photographs (2013) to answer eu pre-selection protocol questions q13 and q14 on the air and direct contact pathways related to the cover of waste heaps, respectively. an example shows the bauxite waste heap in gánt mining area, hungary. in this study the mine waste sites were included inside the rock formations and delineated as polygons using arcgis 10 ® software (fig.2). altogether 30 minequarry waste sites both abandoned mines and active quarries, were selected for scientific testing using the eu mwd pre-selection protocol (stanley et al., 2011; fig. 1). then, by running the protocol, the number of yes, no and unknown responses are registered for each site. preliminary contamination risk assessment of mining waste … 7 the proportion of the certain to uncertain responses for a site and for the total number of sites may give an insight of specific and overall uncertainty in the data we use (table 2). the distance from mine-quarry waste sites to the nearest receptors such as human settlements (q15) is measured using proximity analysis tools (point distance and generate near table) in arcinfo® 10 (fig.2). table 2 summary statistics of the eu pre-selection protocol responses of questions q1-q18, showing the number of yes, no and unknown responses (u) based on the eu thresholds eu pre-selection protocol number of sampled sites eu thresholds yes no u impact q1 30 0 30 0 s o u rc e q2 30 12 18 0 q3 30 14 16 0 q5 30 0 30 0 q8 30 30 0 0 q10 30 21 9 0 p a th w a y q11 30 16 14 0 q12 30 21 9 0 q13 30 18 12 0 q14 30 18 12 0 r e c e p to r q15 30 26 4 0 q16 30 22 8 0 q17 30 19 11 0 q18 30 28 2 0 statistical analyses were carried out using statgraphics centurion xv.ii® software (table 3), such as the topographic slope (q10) and the measured distance to the nearest surface water courses (q11), settlements (q15), ground water bodies (poor status) (q16), protected areas (natura 2000 sites, q17) and agricultural areas (q18). summary statistics of the analyzed heavy metal concentrations from the mine waste sites (aqua regia leaching analysis) were compared to the local (country-specific) thresholds values for geological medium and underground waters in hungary, in addition to the environmental limit values in europe. spearman’s rank correlation is performed on the total concentrations of the analysed elements to determine the relationships and variance between elements in the studied rock samples. moreover, the ficklin diagram is constructed for the sum of heavy metals zn, cr, cd, pb, co and ni against ph in the deionized water leaching (dw, fig. 7). results and discussion the contamination ra according to the eu mwd preselection protocol is carried out using the eu thresholds (slope ≤ 5 o and 1 km distance and number of people in the nearest settlement ≥ 100). the yes, no and unknown responses of the eu mwd pre-selection protocol (fig. 1) were registered and calculated for each question in table 2. in this study each rock formation was treated as a waste site and projected in the map as one or more polygons (fig. 2). questions describe if the mine uses any dangerous chemicals in processing minerals (q4), the geometry of the tailings lagoon height and area (q6-q7) and for the waste heap height (q9) of the pre-selection protocol are not fit to the rock waste sites and were skipped in this study (table 3). out of 30 mine waste sites, none of sites have a documented incident (q1, jordan et al. 2011). in q2, 12 sites with yes responses were producing waste with sulphide minerals, 18 sites have no responses. while in q3, 14 sites were producing minerals with toxic heavy metals. in q5, all sites are waste heaps and none of sites are tailings latable 3 class boundaries of the eu mwd pre-selection protocol parameters based on the natural-breaks found in the corresponding cummulative histograms. class boundaries were used to define thresholds adapted to local conditions in hungary question class boundaries class-range median of class median of all sites number of sites q10 topographic slope below waste site (degree) 1.-20 1.-20 10 10 30 q11 distance to the nearest surface water course (m) <1300 0-1280 188 22 >1300 2219-5376 2861 631 8 q15 distance to the nearest settlement (m) 0 0 0 14 >0<=1000 82-838 548 12 >1000 1585-3319 2350 150 4 q16 distance to the groundwater bodies of 'poor status' (m) 0 0 0 18 >=36 36-14717 5229 0 12 q17 distance to the nearest natura 2000 sites (m) 0 0 0 12 >0<=1000 158-713 286 6 >1000 1072-5548 2416 224 11 q18 distance to the nearest agricultural areas (m) 0 0-861 0 24 59-2092 3688-3976 359 0 6 8 abdelaal (2014) goon. in q8, all 30 waste heap sites with yes responses are greater than 10,000 m 2 in surface area. the slope of the foundation upon which the waste heap rests is of concern with respect to stability. the greater the slope angle the greater the risk of waste heap failure. the eu threshold chosen is 1:12 which equates to 8.3% or a slope angle of almost 5°. based on the slope values derived from the 50m dem, 16 waste heap sites with yes responses are greater than or equal 1:12 (5 o ) in slope (q10). this shows that most of the sites were located in hilly areas. the use of the surface permeability map (fig.5) developed to generate answers for q12, resulted in 21 waste sites with yes responses and underlain by medium and high permeable layer, while 9 sites underlain by low permeable layers. when the mine waste site is covered and the original material is not accessible this means there is no direct contact with receptors. in q13, 18 sites were exposed to the wind and 12 sites were not. while in q14, 18 sites were uncovered and 12 sites were covered with water, vegetation, soil and forest (fig.6). for q11, 16 sites are within 1 km distance to the nearest surface water bodies (streams and lakes). in q15, 26 mine waste sites are within 1 km distance to nearest human settlements with >100 people, indicating that these sites require prime attention if settlement protection is the concern. in q16, 22 sites are within 1 km distance to the groundwater bodies of less than good status. for q17, 19 waste sites are within 1 km distance to the national protected natura 2000 sites. 12 waste sites were located completely inside the natura 2000 sites), this calls for immediate special attention if landscape protection is a priority. moreover, in q18, 28 waste sites are within 1 km distance to the agricultural areas including arable lands, pastures, heterogeneous and permanent crops, 24 sites are completely located inside the agricultural lands (table 2). distribution analysis performed on the heavy metals (table 3) identified various sub-groups in the parameter thresholds of the eu pre-selection protocol. for example, in q10, altogether 30 waste sites have one class of topographic slope ranges from 1-20 o . this result suggests the median slope value of all waste sites 10 o as a natural threshold reflecting the local hungarian conditions, instead of the original 5 o slope threshold. in q11, 22 waste sites were located within distance 0-1280m to the nearest surface water bodies and 8 sites are within distance 2,219–5,376m. this shows that almost 73% of the mine waste sites are significantly (at the 90% confidence) closer (≤1280m) to receiving streams than the other sites, thus the 631m (medial value of all sites) threshold may better reflect the local topographic conditions for this que stion. in q15, 14 waste sites were located directly i nside the nearest settlement (distance=0), indicating that these sites require prime attention if settlement protection is the concern, 12 sites are within distance 82-838m to the nearest settlement and 2 sites are wit hin distance 1,585-3,319m to the nearest settlement. this result suggests the distance 150m (medial value of all sites) as a local threshold for this question in hungary. it is interesting that 18 waste sites lie direc tly above the groundwater bodies with ‘poor status’ (q16) and 12 sites are located inside the protected natura 2000 sites (q17). while in q18, 24 waste sites are located inside the agricultural areas (table 3). a preliminary risk-based site ranking is possible based on the eu thresholds (slope of almost 5 o and 1km distance) by counting and ranking the yes responses of the pre-selection protocol, and ranging in scores from 5 to 10. obviously, if there is more than one hazardous material at the source or there are multiple contamination pathways and receptors the site has a higher risk. a simple risk ranking of the rock formations based on the yes responses in descending order as follows: black coal and peat (10 yes), alginite (9 yes), lignite and clay (8 yes), bauxite (7 yes), bentonite-clay (6 yes) and andesite and rhyolite tuffs (5 yes). in summary, after the existing pre-screening risk assessment of the mine waste sites in hungary, 28 sites were directed to examine further based on the eu thresholds and two sites with no risk (one bauxite site has no pathway and one andesite site has no sensitive receptor). table 4 summarizes the estimated heavy metal concentrations from the mine waste sites (aqua regia extraction) with respect to the environmental limit values in hungary and europe. in case of central tendency expressed by the median, the analyzed heavy metals are in descending order; zn>v>cu>cr>pb>co>ni>as>mo>cd. this result shows that zn has the highest median (24.6 mg/kg) and cd has the lowest median (0.11 mg/kg). in case of spread expressed by iqr/med (interquartile range/median), the heavy metals are in descending order; ni>as>cr>v>pb>co>cd>zn>cu. it is obvious that ni has the highest spread (5.11) and cu has the lowest (1.11). while spread expressed by range/median, the heavy metals are in descending order; ni>cr>mo>co>zn>pb>as>cd>cu>v. ni still has the highest spread (327.6) but in this case v has the lowest spread (8.42). total concentrations of heavy metals as defined by aqua regia extraction were compared to the environmental limit values in hungary and to the european environmental geochemical background values based on the foregs european geochemical atlas (table 4) as follow: the mean of as (18.17 mg/kg) exceeds the tolerated limit in hungarian soils (15 mg/kg) and exceeds the mean value of eu foregs geochemical background value (10 mg/kg). at the same time, the mean of cd (0.33 mg/kg) is less than the tolerated limit in hungarian soils (1 mg/kg) and exceeds the mean of eu foregs (0.3 mg/kg). the mean of ni (61) exceeds the tolerated limit in hungarian soils (40) and exceeds mean of eu foregs (31). moreover, the median of cu (12.3) exceeds the median of eu foregs (12). the spearman’s rank correlations depicted in tables 5 and 6 were performed between each pair of the analysed heavy metals from the waste sites by aqua regia and deionized water leaching analyses, respectively. in contrast to the more common pearson correlations, the spearman coefficients are computed from the ranks of the data values rather than from the values themselves. preliminary contamination risk assessment of mining waste … 9 thus they are less sensitive to outliers than the pea rson coefficients. table 5 shows that all the elemental pairs of aqua regia leaching (with bold figures) have strong correlations with each other which p < 0.05, for example pb and zn(r = 0.63, df = 93, p < 0.05), and ni and pb (r = 0.71, df= 93, p < 0.05) etc. ho wever, pairs such as co/mo, cr/mo, cu/mo, mo/ni, mo/pb and mo/zn show a weak correlation with each other (p>0.05). table 6 shows that all the elemental pairs of deionized water leaching (with bold figures) have strong correlations with each other, for example between co and ni (r= 0.8). moreover, pairs such as as and cd, as and pb, cd and cu, cd and pb, co and mo, cr and zn, cu and pb, mo and pb and mo and zn show a weak but significant co rrelation with each other (p>0.05). strong correlations signify that each pair of elements may have common contamination sources. further detailed studies of physico-chemical properties and metal associations are needed to ascertain these results. table 4 summary statistics of heavy metal concentrations from the mine waste sites (aqua regia extraction in mg/kg) in respect to the environmental limit values in hungary and the european top soil baseline values. minimum (min), maximum (max), median (med) and spread expressed as median absolute deviation (mad), lower quartile (lq), upper quartile (uq), interquartile range (iqr), standard deviation (sd). bold figures show those heavy metal concentrations higher than the environmental standard limits (i.e. the tolerated limit in hungarian soils or eu foregs geochemical atlas baseline value for top soils). as cd co cr cu mo ni pb v zn min 0.6 0.06 0.018 0.537 0.766 0.2 0.4 1.15 3 0.1 lq 1.54 0.073 2.92 2.58 6.8 0.2 1.88 4.56 5.48 14.4 med 3.93 0.117 5.12 8.11 12.3 0.2 4.79 7.08 18.4 24.6 uq 14.3 0.22 9.98 21 20.5 0.2 26.4 14.3 38 46.1 iqr 12.76 0.152 7.06 18.42 13.7 0 24.52 9.74 32.52 31.7 max 247 6.07 416 1185 573 24.3 1570 468 158 1690 mean 18.17 0.33 19.92 56.24 34.16 1.08 60.89 23.4 28.91 84.28 range 246.4 6.01 415.9 1184.4 572.2 24.1 1569.6 466.8 155 1689.9 sd 43.31 0.87 63.67 170.09 92.44 2.96 223.3 68.72 31.64 255.83 mad 3.07 0.057 3.52 6.34 5.7 0 4.25 3.84 13.94 15.8 mode 0.6 0.06 11.5 13.9 0.2 0.4 3 0.1 range/med 62.69 51.36 81.24 146.04 46.52 120.5 327.68 65.93 8.42 68.69 iqr/med 3.24 1.29 1.37 2.27 1.11 0 5.119 1.37 1.76 1.28 mad/med 0.78 0.48 0.68 0.78 0.46 0 0.88 0.54 0.75 0.64 environmental standard values in hungary and the european top soil baseline values (foregs atlas) tolerated limit in soils, hungary 15 1 30 75 75 7 40 100 200 e u f o r e g s min <0.5 <0.01 <1 1 1 <0.1 <2 <3 4 max 220 14.1 255 2340 239 21.3 2560 886 2270 med 6 0.145 7 22 12 0.62 14 15 48 mean 9.88 0.28 8.91 32.6 16.4 0.94 30.7 23.9 60.9 table 5 the spearman’s rank correlation coefficients between concentrations of heavy metals from the waste sites (aqua regia extraction). significant correlation coefficients are in bold; ρ < 0.05. as cd co cr cu mo ni pb zn as cd 0.45 co 0.41 0.34 cr 0.37 0.39 0.72 cu 0.42 0.42 0.77 0.66 mo 0.35 0.22 -0.13 -0.12 0.06 ni 0.57 0.5 0.72 0.81 0.7 0.19 pb 0.5 0.58 0.61 0.57 0.6 0.09 0.71 zn 0.31 0.39 0.86 0.61 0.71 -0.17 0.57 0.63 10 abdelaal (2014) the ficklin diagram (adapted after plumlee et al., 1999) showing the sum of heavy metals zn, cr, cd, pb, co and ni from deionized water leaching (dw) analysis is plotted against ph (fig.7). differences in the sum of the previous base metals have proven the most diagnostic in differentiating between different geologic controls. this diagram shows two groups as follow.(1) coal, lignite, peat and bauxite samples are distributed from acidhigh acid to near-neutral environments, with low to extreme concentrations of dissolved metals. (2) alginate, andesite, clay, rhyolite tuffs and limestone samples are distributed in near-neutral environments, with low to high concentrations of dissolved metals. multivariate analysis such as ca and pca using the analysed trace elements could not identify significant groups of samples. this is not unexpected due to the heterogeneity of the sampled rock types. it seems that specific rock formations with ore mine rals content, including pyrite with acid generation potential, such as some andesites and coals are di stinct from the non-mineralised as shown by the ficklin diagram (fig.7). the relative mobility of heavy metals in the various sampled rock formations was calculated as the percentage of the mobile element content (deionized water leaching) to the total element content (aqua regia extraction) for the 93 samples. then the median value of these mobility percentages was calculated for each rock type (fig.8). results show in black coal samples, the relative mobility of the heavy metals reduced in the following order: zn (30.7) > co (29.5) > ni (26) > v (11.2) > cd (4.6) > cu (2.3) > pb (0.3) > as (0.27) > mo (0.26). in lignite samples, mo (5) > v (4.6) > as (1.4) > cd (1.2) > zn (0.8) > pb (0.5) > co (0.3) > ni (0.2) > cu (0.16) > cr (0.1). in peat samples, zn (31) > v (16) > mo (6) > cd (3) > as (2.5) > co (1.3) > pb (0.8) > cu (0.7) > cr (0.4) > ni (0.3). in bauxite samples, mo (5) > cd (0.7) > v (0.4) > as (0.3) > co (0.11) > pb (0.1) > zn (0.06) > cu (0.05) > ni (0.03) > cr (0.01). in alginite samples, mo (175) > v (2.1) > cd (0.6) > as (0.2) > pb (0.08) > cu (0.04) > ni (0.03) > zn (0.025) > co (0.02) > cr (0.01). in clay samples, mo (8.7) > v (2.3) > cd (1.8) > zn (0.5) > as (0.4) > pb (0.2) > co (0.1) > ni (0.07) > cu (0.05) > cr (0.04). in andesite samples, mo (5) > cd fig.7 ficklin diagram showing the sum of heavy metals zn, cr, cd, pb, co and ni plotted against ph in the deionized water leaching (dw). note that acid generation potential (ph<5.5) is for coal, lignite and peat rocks, in addition to a bauxite sample. elevated mobile heavy metal content is associated with coal, andesite and some clay and a bauxite samples. see text for details. table 6 the spearman’s rank correlation coefficients between concentrations of heavy metals from the waste sites (deionized water leaching). significant correlation coefficients are in bold; ρ < 0.05. as cd co cr cu mo ni pb zn as cd 0.12 co 0.22 0.27 cr 0.03 0.25 0.26 cu 0.17 0.16 0.35 0.18 mo 0.28 0.08 -0.04 0.1 0.27 ni 0.21 0.3 0.8 0.28 0.47 0.16 pb -0.04 0.14 0.31 0.24 0.14 0.01 0.26 zn 0.14 0.02 0.27 -0.04 0.47 0.11 0.35 0.12 preliminary contamination risk assessment of mining waste … 11 (4) > as (2.5) > v (1.6) > ni (0.7) > pb (0.6) > zn (0.4) > co (0.2) > cu (0.15) > cr (0.14). while in rhyolite tuffs samples, v (16.6) > mo (5) > ni (4) > cd (3) > as (2.3) > co (2) > zn (1.2) > cr (0.8) > cu (0.7) > pb (0.2). it is obvious that mo had the highest mobility in lignite, bauxite, alginite, clay and andesite rock samples and zn had the highest mobility in black coal and peat samples. while, v had the highest mobility in rhyolite tuffs samples (fig. 8). fig. 8 distribution of the relative mobility (%) of heavy metals in the various sampled rock formations based on the expert judgment, the listed rock formations were classified into three preliminary categories. a: inert b: probably inert, but has to be checked c: probably not inert, has to be examined (table 1). according to the geochemical analysis results in this study, coal (black coal and lignite) and peat samples are not inert and classified into group c which matches with the preliminary expert judgment. while alginite, bauxite, rhyolite tuffs and clay samples are probably inert and classified into b group which also matches with the preliminary expert judgment. moreover limestone and clay samples are inert (a group). it is interesting to report that andesite samples are probably inert (b group) and according to our geochemical analyses, it was found that 5 andesite samples contain higher concentrations of the heavy metals ni, zn cu, cr and co than the minimum, median and mean values of the hungarian standards. while as is even higher than the maximum values of the national environmental standards. these results may suggest that those 5 andesite samples with higher heavy metal concentrations could classify the andesite rock formation into the b or c groups. conclusions this paper discusses the heavy metal contamination risk assessment (ra) in a selected group of the mine waste sites in hungary. a detailed geochemical study together with spatial analysis using gis was performed to derive a geochemically sound contamination ra of the mine waste sites. key parameters such as heavy metals, in addition to the landscape parameter such as the distance to the nearest surface and ground water bodies, or to sensitive receptors such as settlements and protected areas are calculated and statistically evaluated in order to calibrate the ra methods. in deionized water leaching, coal, lignite, peat and bauxite samples were located in one distinct group in the ficklin diagram and distributed from acid to near-neutral region in the graph with low to extreme concentrations of dissolved metals. while alginate, andesite, clay, rhyolite tuffs and limestone samples were located in one group and distributed in the near-neutral region, with low to high concentrations of dissolved metals. a simple risk ranking of the waste rock materials based on the yes responses to risk factor questions in descending order of risk resulted as follows: black coal and peat (10 yes), alginite (9 yes), lignite and clay (8 yes), bauxite (7 yes), bentonite-clay (6 yes) and andesite and rhyolite tuffs (5 yes). after the existing prescreening risk assessment of the studied waste sites in hungary, 28 sites were directed to examine further based on the eu thresholds and two sites with no risk. results show that some of the waste rock materials, assumed to be inert such as the 5 andesite sites that contain higher concentrations of the heavy metals as, ni, zn cu, cr and co than the minimum, median and mean values of the hungarian standards. these results may suggest that those 5 andesite samples with higher heavy metal concentrations could reclassify the andesite rock formation into the b and c groups. thus, regional ra needs further spatial and petrological examination with special care to rock and mineral deposit genetics. acknowledgment the hungarian scholarship board (mob-grant) is gratefully acknowledged. a special thank is given to the reviewers for their useful comments. it is noted that this study has no relationship to the reported national inventory by any means and the site data used for this scientific study is not based on the reported inventory. references abdaal, a., jordan, g., szilassi, p. 2013. testing contamination risk assessment methods for mine waste sites. water, air, & soil 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geography journal of environmental geography 9 (3–4), 43–48. doi: 10.1515/jengeo-2016-0011 issn: 2060-467x estimation of the changes in the rainfall erosivity in hungary gábor mezősi*, teodóra bata department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: mezosi@geo.u-szeged.hu research article, received 1 september 2016, accepted 15 november 2016 abstract according to the forecasts of numerous regional models (eg. remo, aladin, pregis), the number of predicted rainfall events decreases, but they are not accompanied by considerably less precipitation. it represents an increase in rainfall intensity. it is logical to ask (if the limitations of the models make it possible) to what extent rainfall intensity is likely to change and where these changes are likely to occur in the long run. rain intensity is considered to be one of the key causes of soil erosion. if we know which areas are affected by more intense rain erosion, we can identify the areas that are likely to be affected by stronger soil erosion, and we can also choose effective measures to reduce erosion. this information is necessary to achieve the neutral erosion effect as targeted by the eu. we collected the precipitation data of four stations every 30 minute between 2000 and 2013, and we calculated the estimated level of intensity characterizing the carpathian basin. based on these data, we calculated the correlation of the measured data of intensity with the values of the mfi index (the correlation was 0.75). according to a combination of regional climate models, precipitation data could be estimated until 2100, and by calculating the statistical relationship between the previous correlation and this data sequence, we could estimate the spatial and temporal changes of rainfall intensity. keywords: rainfall intensity, regional differences of r, data of remo and aladin models introduction soil erosion is one of the greatest environmental threats, which causes significant environmental damage in hungary. its extent has been estimated lots of times, and it affects about 2 million hectares (stefanovics, 1992). in order to prepare long-time estimations concerning the regional change tendencies of soil erosion, we have to pre-estimate dynamic parameters and factors. (in 2015, the eu set an ambitious goal to reduce the extent of soil erosion to zero.) the aim of the present analysis is to pre-estimate the temporal changes of rainfall erosion potential of the dynamic parameters. by doing so, we will receive information about one of the most important factors of soil erosion. even if it is all about tendencies, detecting temporal and spatial changes in rainfall intensity may serve as important information to take extended-range measures to reduce the effects of erosion. in addition to geomorphological and soil data, dynamic (land cover) as well as numerous static factors may also be required to estimate the extent of soil erosion. our study aims at revealing major changes of the r value in the present study. there are lots of uncertainties that result from using the data of the applied regional climate models, and, besides these, we also have to take into account that such social and economic changes may happen in the next few decades that may also change climate and land cover data predicted earlier. our results must be interpreted within these limitations. soil erosion processes are characterized by a lot of theoretical and empirical models. however, the parameters of the processes can be well-defined. for example, rainfall intensity and land cover (c) are dynamic parameters in the universal soil loss equation (usle), while the others are static ones. it is a complex task to calculate rainfall intensity and the erosion potential associated with it. rainfall erosivity factor (r) is expressed by summarizing the energy values of each rainfall event in a given period (wischmeier smith, 1978, wischmeier, 1959). the rainfall erosivity factor is calculated by multiplying the kinetic energy of precipitation (e) by the maximum rainfall intensity during a period of 30minutes for each rainstorm (exi30). rainfall erosivity (r) expresses the collective erosivity value of locally occurring rainstorms (table 1). the logic of the calculation dates back to the 1961s (wischmeier, 1959), but it gained wide recognition when the universal soil loss equaiton became commonly used (1978) as it was one of its parameters. table 1 calculating the rainfall erosivity factor rainfall erosivity factor (r) (mj/ha.cm/h) r = e x i30/ 100, where i30 – maximum rainfall intensity during a period of 30-minutes for each rainstorm (cm/h), e – total kinetic energy of precipitation (j/m2) total kinetic energy of precipitation (e) (j/m2) e = ∑ e𝑖 𝑛 𝑖=1 , where ei the kinetic energy of the i segment of precipitation (n is the number of segments) ei = (206 + 87 log isi) x hsi , where isi – the intensity of the i segment of precipitation (cm/h), hsi – the amount of the i segment of precipitation (cm) 44 mezősi and bata (2016) in hungary, r factor values vary between 360 and 1,000 (panagos et al., 2015), and they are characterized by small-scale variance as a result of the homogeneous environmental features of the country. (the calculation is based on the ten-minute precipitation data of 30 rain gauges between 1998 and 2013.) it has an average value compared to other european data, and it is also far below the great, 4,000 to 6,000 mj/ha rainfall intensivity values of the continent. former hungarian local test results usually recorded data in this interval (kertész and richter, 1997: 49-59 mj/ha; centeri, 2002: 76 mj/ha; jordán et al., 2004: 809 mj/ha; szűcs, 2012: 60-512 mj/ha). homogeneity is expressed in the elevation, the climate type, and the general water balance, although different soil conditions would require different land use in order to reduce soil erosion. despite the relative homogeneity of the environmental factors, territorial differences are visible (if not otherwise, then their impact is). we also aimed at estimating this spatial difference concerning the future periods. rainfall intensity can be calculated by two different methods. one of them operates with great temporal resolution using a minimum of 30-minute precipitation data. the other one does not have such high temporal resolution data, it calculates intensity with more easily accessible precipitation data by employing parameters which are significantly correlated with r. the frequent use of the latter method also shows that there is no widely accepted and widely applied method for calculating rainfall intensity. the different precipitation data and their correlations can only be used with quantitative (eg. with <12.7 mm of rainfall otherwise at ei default event) and qualitative (e.g. fixed drop size ratio) prerequisites, and they can be converted to mjha 1cmh-1 value. a weakness of the commonly used empirical formula is that it presupposes the existence of precipitation data series dating back to several decades, and the correlation was tested on plot-sized areas. the erosion factor (r) is usually the average value of the data collected during several years. there are usually not any data (which would be detailed enough) available to calculate the rainfall erosivity factor, so a lot of alternative parameters were developed by using daily and annual precipitation data to substitute the value of the r factor. these parameters are typically such indices that are related to smaller areas, and they are used at the maximum of meso-level. they often show as good correlation with soil erosion as the r index (eg. fournier p²/ p index, rem index lal's aim index, p/st universal index) (fournier, 1960; arnoldus, 1980; daidato, 2007; onchev, 1985; sauerborn et al., 1999; renard et al., 1994 table 2). these indices also show at least as strong a correlation with the rainfall erosivity index as the e xi 30 calculated by wischmeier. the rainfall erosivity factor (r) was also estimated by using other precipitation data, but they usually did not live up to the expectations (eg. deumlich et al., 2006). the result of the large number of measurements is that there is not a one and only sure method of calculating the rainfall erosivity factor due to the large number of active components and their plot-specific nature (although it would be important in order to estimate soil erosion, for example). measuring soil table 2 a compilation of alternative methods of calculating rainfall erosivity authors alternative methods of calculating rainfall erosivity remarks fournier, 1960 f = p2/p, where p is mean monthly precipitation, and p is mean annual precipitation fournier index arnoldus, 1980 mfi = ∑12i=1 pi2/p, where pi is mean monthly precipitation, and p is mean annual precipitation modified fournier index onchev, 1985 r = p/st, where p is > 9.5 mm rainfall intensity, st is the time of a > 0.18mm/min rainstorm universal precipitation event index / universal index for calculating rainfall erosivity renard – freimund, 1994 r = 0.07397 f1.847 r = 95.77 – 6.08 f + 0.477 f2 f<55mm f>=55mm sauerborn et al., 1999 rs = 33.2 + 2 x fims (r2 = 0.64) fournier index with summer months fao – colotti, 2004 r =a x mfi + b a and b are two regionally defined parameters deumlich et al., 2006 r = 12.98 + 0.0783 x p, where p is annual precipitation mean annual precipitation diodato – bellocchi, 2007 rm = b0 x [pm (f(m) + f(e, l)]b1 rm is based on monthly precipitation eltaif et al., 2010 r = 4x 10-6xf3.5874 monthly precipitation data hernando – romana, 2015 r = 0.15 p, where p is annual precipitation data r = 2.51 f, where f is the fournier index r = 1.05 mfi, where mfi is the modified fournier index >5-year-long simulation > 10-year-long simulation >10-year-long simulation estimation of the changes in the rainfall erosivity in hungary 45 erosion requires an extensive collection of both spatial and temporal data (eg. 10-to-30-minute precipitation data, and a sufficient number of rain gauges, or pluviographs). as they often were and/or are available, a lot of methods were developed to estimate this factor by employing easily obtainable data (table 2). the r factor was often introduced as an index that significantly correlates to soil erosion (wischmeier, 1959; wischmeier and smith, 1978; lo et al., 1985). several alternative indices were also connected to rainfall erosivity. most of these indices had a strong correlation with the fournier index that uses monthly and annual mean precipitation data (1960), which index assesses the extent of erosion by using the p2/p (average monthly/annual rainfall) correlation. the subsequent modification of the fournier index (mfi) defined an even stronger correlation, and it eventually showed its connection with soil erosion. preparing soil erosion models requires such precipitation information that is very time-consuming and cost-intensive to obtain, and it is often without measurable benefits. the r value often correlates well with other readily available rainfall data in the long run. of course, the result is usually also true: high erosivity rainfalls result in high r values. from the alternative calculations, the readily available monthly/annual precipitation data were investigated, a lot of researchers also used these data for extreme values, e.g. for >100 mm precipitation. other researches preferred to have a greater number of rain gauges (>100) or excluded extreme values (eg. >1,000 mm, exclusion of winter precipitation) in order to secure a strong correltaion between the mfi and the r index (typically 0.8) (renard, 1997; van dijk et al., 2002; hernando 2015). study area and methods in our study the major changes of r were evaluated in hungary, as study area. the method we applied consisted of the following steps: step 1: we calculated the r value on the basis of the 10-minute rainfall data of 4 meteorological stations in hungary (szeged, agárd, pécs, debrecen) as shown in table 1, and we used the available data series from 1999 to 2014. we calculated the modified fournier index on the basis of mean monthly and mean annual precipitation data as shown in table 2 for the same period. then we calculated the correlation between the rainfall intensity (r) and the modified fournier index (mfi) data series. step 2: we calculated monthly and annual precipitation data by averaging the daily data of this century on the basis of the remo and aladin regional models (mezősi et al., 2013). these models did not provide detailed data on rainfall events, which could have helped to estimate the spatial and temporal changes of rainfall intensity. these average values were the raw data of the mfi values concerning certain intervals of this century. step 3: we used the so-gained correlation between the r and the mfi to do the calculations for this century. by employing it as a linear relationship, we could estimate the r values as we also had knowledge of the mfi values of this century. in addition to the linear nature of the relationship calculated by fao (which is also used in the study), other relationships can also be interpreted (table 2). step 4: we calculated the r values for the periods of 2021-2050, and 2071-2100. for both the near and the distant future, we prepared the average results as the average of every five years, then we visualized these data on maps. we edited the maps by kriging which was based on the data relating to the given settlements. the small number of data limits the preparation of statistical maps. this disadvantage is reduced by the nature of the results which were created to raise awareness about both time periods. it could not be calculated for the target data model limited of uncertainty, respectively. we did not aim at preparing a more accurate spatial and temporal estimation of rainfall intensity as it was restricted by the limitations and uncertainty of the computed model data, and the limited possibilities of the applied calculation. applying the gaussian process regression slightly improved the geostatistical method that had been based on little data. practically it meant that elevation (despite the study area having relatively small elevation differences) as a supportive parameter was included in generating the pattern of the r factor when the maps were being produced (goovaerts, 1999). results we calculated the correlation of the r factor with the data measured for the 1999-2014 period by applying the modified fournier index (mfi) for a linear relationship, (figure 1). more than three dozens of such rainfall events occurred during that period which were characterized by >12.7 mm of rainfall. the correlation was 0.74 which indicates a significant relationship between the two parameters as the limit is 0.4 with a 1% probability. hernando and romana (2015) studied a smaller spanish area with eight stations for a longer time period, and calculated a >0.8 correlation. it further strengthens the relationship between the r and the f/mfi/p that had already been proven by numerous researches earlier, however, it does not exclude further analyses. fig. 1 the correlation between rainfall intensity (r) and the calculated mfi value on the basis of 10-minute data recorded from 1999 to 2014 46 mezősi and bata (2016) changes in rainfall intensity can also be studied annually. the annual results of the r value using simulated data increase in the 30-year time period. we give two examples of our calculations calculated by the average values of the remo and aladin models between 2021 and 2050. these results demonstrate that intensity varies both spatially and temporally (fig. 2). the initial values are characterized by 750 mj/ha intensity, which is characteristic of the average values of the past 25 years (panagos et al., 2014), and their increase is clearly observable from 2021 to 2050. changes in the pattern of the r often follow the changes of relief (even if elevation differences are modest) and the changes in the amount of rainfall. the deviation of the r data shows a more significant change which is greater than the increase in the r values. figure 2 represents the annual data displaying this change. the uncertain, simulated basic data can be evaluated on the basis of the average values of longer time periods. figure 3 displays the r values modeled for a nearer time period broken down by five years. the average figures for the short period support the fact that these data are not sufficient enough to reach an easily recognizable and well-established conclusion. however, when comparing to the average raw data of the 1961-1990 interval that served as the base of our study, we can see that the r value usually differs positively. the changes do not exhibit regional trends though. therefore, the average data of longer periods provide more reliable information. changes in rainfall intensity can be obtained by using average model values. the comparison was related to the average value calculated for the years between 1961 and 1990 which served as raw data. the regional climate models used in our study do not give the same known results when calculating the quantity of rain. the results of the models are, therefore, separately included (table 3), but regional conclusions were drawn on the basis of the average values. the rate of growth both in the proximal and distant intervals is significant, it is more than 50% of the current value. compared to the raw data, the r value can as well be doubled, but it is not extremely high concerning european data. other european peak values of the r index exceed 4,000, while the maximum mean value is 1,500 in hungary. in addition, the environmental features and economic conditions of the carpathian basin are also remarkably different. this increase is in line with the projected growth of heavy rainfalls of >30 mm of rainfalls in the 21st century as the model results indicate. the increase of the mean r value can also be estimated locally. the joint calculations of the remo – aladin models show the changes of mean values in figure 4. the biggest change can be seen in the central and northwestern parts of the carpathian basin in this period. fig. 2 rain intensity values in two years of the modeled time period from 2021 to 2050 fig. 3 changes in the r value compared to the raw data of the 1961-1990 period estimation of the changes in the rainfall erosivity in hungary 47 discussion and conclusion according to earlier analyses, the rainfall intensity index of the carpathian basin increased in the summer over the past 100 years (lakatos et al., 2011). based on the modeled characteristics of different climate change scenarios (eg. the number of rainy days, >30 mm of rainfalls), the previously mentioned growth characterizing the summer is not likely to continue, but the annual intensity is likely to increase due to fewer but heavier, more intense rainfall events (tables 4 and 5). the amount of precipitation will not become less, but its annual distribution will be rearranged. the 20% reduction in summer precipitation will be compensated by the increase in winter precipitation, but the growing number of more intensive rainfalls indicates an increase in rainfall intensity. in order to estimate the r value for this century, we used the modified fournier index. we could reveal a significant correlation between the r and the mfi by using the precipitation data of the past nearly 30 years. by applying this trend and the data provided by the model results, we calculated a 50-80% increase in rainfall intensity for this century. yet, the estimated 1,000-1,500 mj/ha increase in intensity significantly lags behind the maximum values (5,000 to 6,000 mj/ha) of certain regions in italy, croatia, or slovenia (as well as western scotland and southern spain) (panagos et al., 2014). the estimated value of r concerning hungary comes near to the contemporary mean r values (1,300-1,600 mj/ha) of the previously mentioned countries. of course, it must be taken into account that the carpathian basin is characterized by very different environmental features and land use. one of the most obvious effects is how the increasing precipitation intensity influences agriculture. in order to measure it (either on model or standard hungarian levels), versions of the wischmeier-smith formula (epic, usle, rusle, etc.) are used the most. although they operate with 5-7 variables, rainfall intensity (r) is the one that affects the extent of soil erosion the most. in terms of the extent of soil erosion, slope length, steepness, soil type are also sensitive parameters, but they can be considered stable at this scale. land cover is also susceptible to the extent of soil erosion. in our case, however, the change should be a consequence rather than the cause of soil erosion growth. a change in land cover/land use could be a point of intervention which could help reduce the extent of erosion. calculating the extent of soil erosion is not easy because the critical period from may to september. the climate data provided by the models predict greater r values and greater erosivity values in the long run despite decreasing summer precipitation. apart from the rainfall erosivity factor, the extent of soil erosion is also regulated by terrain-, soil-, and land-cover-related data. the complexity of the system means that the conclusions drawn from the r data can only be considered as the mean values of longer periods, but the consequences of their possible effect may be useful to provide support for regional development. table 3 changes in the r value compared to the base period (1961-1990) aladin remo 20212050 2071-2100 20212050 2071-2100 mean +60.45 % +50.99 % +51.93 % +53.17 % minimum +41.38 % +28.79 % +27.86 % +29.81 % maximum +90.37 % +72.61 % +82.11 % +86.19 % fig. 4 the increase of the mean r value for the years 2071-2100 as calculated with remo–aladin data 48 mezősi and bata (2016) on the basis of our results, it is necessary to provide more reliable and accurate raw data to define the r value (eg. using the ensembles model), and to further investigate soil erosion by applying vegetation 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(eds.): soil erosion and conservation. soil conservation society of america, ankeny, 424–431. panagos, p., ballabio, c., borrelli, p., meusburger, k., klik, a., rousseva, s., tadić, m.p., michaelides, s., hrabalíková, m., olsen, p., aalto, j., lakatos, m., rymszewicz, a., dumitrescu, a., beguería, s., alew, ch. 2015. rainfall erosivity in europe. science of the total environment 511, 801–814. doi: 10.1016/j.scitotenv.2015.01.008 renard, k.g., freimund, j.r. 1994. using monthly precipitation data to estimate the r-factor in the revised usle. j. hydrol., 157, 287– 306. doi: 10.1016/0022-1694(94)90110-4 sauerborn, p., klein, a., botschek, j., skowronek, a. 1999. future rainfall erosivity derived from large-scale climate models — methods and scenarios for a humid region. geoderma 93. 269– 27. doi: 10.1016/s0016-7061(99)00068-3 stefanovics, p. 1992. talajtan. mezőgazda kiadó, budapest. szabó, p., horányi, a., krüzselyi, i., szépszó, g. 2011. the climate modelling at hungarian meteorological survey: aladin and remo. 36. meteorológiai tudományos napok omsz, budapest, 87–101. szűcs, p. 2012. az erózió lépték függése. phd dissertation. pannon egyetem keszthely p. 146. wischmeier, w.h. 1959. a rainfall erosion index for a universal soilloss equation. soil sci. soc. am. proc. 23 (3), 246–249. doi: 10.2136/sssaj1959.03615995002300030027x wischmeier, w.h., smith, d.d. 1978. predicting rainfall erosion losses. a guide to conservation planning. agriculture handbook no. 537. u.s. department of agriculture, washington, d.c table 4 changes in the amount of annual precipitation in mm compared to the base data of the 1961-1990 period as calculated by the remo and aladin models (szabó et al., 2011) period annual mean spring summer autumn winter 2021-2050 -1 to 0 -7 to +3 -5 +3 to +14 -10 to +7 2071-2100 -5 to +3 -2 to +2 26 to -20 +10 to +19 -3 to +31 table 5 changes in precipitation and temperature compared to the base data of the 1961-1990 period as calculated by the remo and aladin models (blanka et al., 2013) parameter the extent of change compared to the mean values of the 1961-1990 period remo 2021-2051 aladin 2021-2051 remo 2071-2100 aladin 2071-2100 precipitation (mm/year) -42.6 – 58.5 -31.6 – 53.1 -16.5 101 -21.4 (-84.2) temperature (°c/year) 1.2 – 1.5 1.7 2 3.4 – 3.7 3.4 – 3.7 rr> 30 mm (day/year) 0.7 – 1.0 0.6 – 1.2 1.0 – 1.5 0.9 – 1.3 introduction study area and methods results discussion and conclusion references journal of environmental geography journal of environmental geography 7 (3–4), 31–42. doi: 10.2478/jengeo-2014-0010 issn: 2060-467x the role of habitat types and soil physicochemical properties in the spread of a non native shrub lantana camara in the doon valley, western himalaya, india gautam mandal * , shambhu prasad joshi *ecology research laboratory, department of botany, dav (pg) college, hnb garhwal central university, dehradun–248001, uttarakhand, india *corresponding author, e-mail: gautam231@gmail.com research article, received 23june 2014, accepted 20 october 2014 abstract invasive alien species colonize very aggressively and forcefully, menacing native biodiversity. the success of invasive alien plants is due to their opportunistic exploitation of anthropogenic disturbances, the absence of natural enemies, free from herbivory and frequently their allelopathic competition. invasive species can have a significant impact on development, affecting sustainability of livelihood, food security and essential ecosystem services and dynamics. lantana camara is a documented weed of worldwide significance; it is indigestible due to its toxic chemicals and highly competitive. in this study physicochemical properties of soil were analysed from different high and low lantana infested areas. significant site effect was frequently observed than effect due to invasion status. the present study tested the impact of soil properties in the measured and calculated attributes of lantana by randomly sampling soil from the highly invaded and less invaded sites in different habitats using the modified whittaker plot design. results indicated that edaphic factors such as soil ph, total nitrogen, soil organic carbon, phosphorus and potassium content positively influenced the growth of lantana and helped in its own further invasion process. these factors were also positively influencing the measured and calculated attributes of lantana such as canopy coverage, average crown diameter, shrub canopy area, phytovolume and biomass from all sites. however some attributes like shrub height and stem diameter were negatively influenced by these soil factors. the present results show that lantana invasion can significantly improve the soil nutrient level but also positively increasing the chances of its further invasion with more copious plant attributes. keywords: invasive alien plants, soil physicochemical properties, biomass of shrub, geomorphology, principal component analysis introduction the invasive alien species are well thought-out to be the second principal cause of biodiversity loss after habitat destruction (schwartz et al., 1996; shinwari et al., 2012). the negative impact of such plant species on native biodiversity has been well documented (d’antonio and mahall, 1991; ridenour and callaway, 2001). invasive alien plants have been found to change the structure and composition of native communities and been associated with reduced native plant diversity (bone et al., 1997; ferreira and marques, 1998; shinwari and qaisar, 2011). introduced species severely threaten some native flora and fauna communities, either directly or by modifying ecosystem process and functions (gordon, 1998; hulme, 2006; vitousek et al., 1997). the introduction of non-native plants or animals has usually been deliberately facilitated by humans, and although most introduced species do not deleteriously affect ecosystems, a small proportion become invasive (hulme, 2006). traits that enable introduced species to persist or spread successfully include high fecundity, good defence mechanisms, high survival rates, adaptability and a lack of natural enemies such as predators and diseases (cheal et al., 2006). introduced species that become invasive can have catastrophic effects on native biodiversity assets and ecological processes by altering nutrient levels, hydrological cycles, fire regimes and community composition, including the removal of keystone species (brooks et al., 2004; d'antonio and vitousek 1992; le maitre et al., 1996; vitousek and walker 1989; yurkonis et al., 2005). for conservation strategies to be successful, it is essential that the introduced species, both plant and animal, that pose major threats, be identified and the mechanism through which they threaten biodiversity assets be understood. india is suffering from the impacts of invasive alien species in many ways. recently it was reported that the alien flora of india accounts for 1599 species, belonging to 842 genera in 161 families and constituting 8.5% of the total vascular flora found in the country (khuroo et al., 2012). the negative impacts have been felt through losses of grazing, agricultural production and for some species, human health (kohli et al., 2006). the himalayas on the other hand is well recognized for its ecosystem services to the asian region as well as to the world at large for maintaining slope stability, regulating hydrological integrity, sustaining high levels of biodiversity and human wellbeing. mountains, due to their exclusive and inimitable biodiversity, are recently receiving priori32 mandal and joshi (2014) ty for biodiversity conservation in global agendas. the western himalayan part is a dynamic landscape with a rich and remarkable biodiversity (guangwei, 2002). the western himalayan region is endowed with a rich variety of gene pools and species, and ecosystems of global importance. the region, with its varied landscapes and soil formation, and variety of vegetation types and climatic conditions, is well known for its unique flora and fauna, and has a high level of endemism (myers et al., 2000) and numerous critical eco regions of global importance (olson et al., 2001; olson and dinerstein, 2002). total forest cover of the country is 697,898 sq. km (69.79 million ha) which is 21.23% of the geographical area of the country. the total tree cover of the country is estimated to be 91,266 sq.km (9.13 million ha) which is 2.78% of the total geographical area. the present study site doon valley is a part of uttarakhand state which is situated in the western himalaya. the state of uttarakhand has a geographical area of 53,483 sq. km, of which 4785 sq. km area is covered by very dense forest (vdf), 14,111 sq. km area is covered by moderately dense forest (mdf) and 5612 sq. km area comes under open forest (of) giving a total forest cover of 24,508 sq. km which is 45.82% of the total geographical area (isfr, 2013). the doon valley is surrounded by sal (shorea robusta gaertn. f.) hereafter, shorea robusta forest, where number of tree species are co-dominant such as syzygium cumini, mallotus philippensis, terminalia alata, tectona grandis, ficus benghalensis, cassia fistula, ehretialaevis, adina cordifolia, bauhinia variegate, flacourtia indica. these forests are invaded by number of exotic species. a large number of exotics have become naturalized in india and have affected the distribution of native flora to some extent, only a few have conspicuously altered the vegetation patterns of the country. lantana camara, cytisus scoparius, chromolaena odorata, eupatorium adenophorum, mikania micrantha, mimosa invisa, parthenium hysterophorus and prosopis juliflora are important among terrestrial exotics and are heavily distributed in the doon valley forests. lantana is one of the most obnoxious weeds that has encroached most of the areas under community and reserve forestlands of western himalaya. the outer fragile himalayas are almost completely enraptured by this rapidly spreading weed. this weed, not only ruins common agricultural and forestlands but also makes shade as well as alellopathy impacts on the regeneration of important forestry species. due to spread of lantana, the yields of crops and pastures get reduced. the harvesting costs have increased manifolds. heavy expenditure is incurred for afforestation of lands infested with this weed which requires frequent weeding so as to avoid suppression of young seedlings of planted species. apart from its popularity as a garden plant, lantana is said to form a useful hedge and to provide a good preparation for crops, covering the ground with fine leaf mulch. it improves the fertility of rocky, grave, or hard laterite soils, enriches the soil, and serves to retain humus in deforested areas and checks soil erosion. it can serve to nurse the parasitic sandalwood seedlings and in the pacific islands has been used as a support for yam vines. lantana leaves and twigs are often used in india as green mulch. the plant is not readily eaten by cattle unless pasturage is very scarce. in tropical countries, the ripe blue black berries are eaten, but ingestion of the green berry has led to human fatalities (ross, 1999). lantana has been introduced in india through one of the human orchestrated movement of plants which has often been found responsible for movement of plants from their native areasto other countries as introduced ornamental plants (fig. 1). there is much evidence that invasive plant species can modify physical or chemical attributes of soil, including inputs and cycling of nitrogen and other elements (ehrenfeld, 2003; haubensak et al., 2004; hawkes fig.1 map showing years of transport and introduction of the woody shrub lantana camara, across the world, from its native countries. adopted with modification from cronk and fuller (1995) the role of habitat types and soil physicochemical properties… 33 et al., 2005), ph (kourtev, 2002a), and soil organic matter and aggregation (saggar et al., 1999). there is also evidence of direct modification of various components of the biotic composition of invaded soil, e.g., affecting a soil food web (duda et al., 2003) total soil microbial communities (kourtev et al., 2003) and mutualistic fungi (hawkes et al., 2005). as noted, these effects will enable plant invasion by positive feedback with soil attributes only if invasive species are benefited, and indeed there are clear indications of such benefits. in temperate oldfield communities, modification of soil micro biota by common invasive species typically had beneficial or neutral effects on growth of these species (agrawal et al., 2005) and micro biota associated with roots of several invasive woody species have increased growth of these species (bray et al., 2003). most changes in species composition reflect changes in soil water nutrient availability and changes in availability of essential plant resources such as light, nutrients and water may result in a change in vegetation community composition (clegg, 1999). according to the review given by chatanga, 2007 nutrient dynamics may become altered as a result of changes in the physical properties of the soil caused by the introduction of an alien species such as lantana but it is not always the case that soil properties will be altered following alien species invasion. lantana population persistence also occurs through processes unrelated to allelopathy such as edaphic effects and changes in ecosystem functioning (gentle and duggin, 1997a, chatanga, 2007). these processes may facilitate ongoing suppression of indigenous species by altering nutrient cycles and modifying microenvironments and disturbance regimes (van wilgen and richardson, 1985). lantana also has negative effect on soil water supply (hieramath and sundaram, 2005, chatanga, 2007).the dense stands of this shrub vegetation and the capacity of the soil beneath to absorb rain which could potentially increase the amount of runoff and the subsequent risk of soil erosion in areas infested with this shrub (day et al., 2003). increase in the soil nitrate following lantana invasion to the benefit of this shrub and to the detriment of some native species and decline in other nutrients. in australia, the moisture content and ph were not significantly affected by lantana. the allelochemicals produced by this woody shrub could alter the populations of soil microbial symbionts necessary for the early establishment of certain seedlings (vranjic et al., 2000). few study sites investigated in the present study were heavily forested with northern subtropical moist deciduous forest having an admixture of a variety of species in four tier structures (top canopy, middle strata, understory shrub and herb strata) with shorea robusta as predominant tree species and understory heavily covered by lantana camara and chromolaena odorata. the studies in different vegetation communities of indian subcontinent and australia, which were based on infertile sandstone derived soils, nutrient enrichment was found to be the key factor that facilitates exotic species invasion (king and buckney, 2002; lake and leishman, 2004; leishman et al., 2004; leishman and thomson, 2005; hill et al., 2005). this was also consistent with the intermittent resource hypothesis of invasibility proposed by davis et al. (2000). davis et al. (2000) suggested that a plant community is more susceptible to invasion when there is an increase in the amount of unused resources, such as nutrients. in above mentioned studies it was found that invasion success of plants like lantana in sandstone-based vegetation depends on nutrient enrichment, which occurs mainly through nutrient rich storm water runoff from impervious surfaces, such as roads within a developed catchment, entering the bushland and flowing into the bay systems (hill et al., 2005). these same anthropogenic influences, roads and nutrient enriched runoff, as well other factors associated with agricultural production, occur in areas of the doon valley in western himalaya (fig. 2). thus, we might hypothesize that invasion by exotic plants may be facilitated by nutrient enrichment in the valley’s vegetation communities also. alternatively, the naturally more fertile shale derived soil of doon valley may make it less vulnerable to nutrient facilitated exotic plant invasion. fig. 2 bioclimatic niche model of probable lantana camara occurrence generated by automated open modeller algorithm, adopted and modified from bhagwat et al. (2012) 34 mandal and joshi (2014) the aims of this study were to determine the relative effect of different anthropogenic disturbances in doon valley on vegetation composition and soil characteristics and to investigate whether there are significant correlations between various soil attributes and the success of exotic woody shrub species lantana. we selected six study sites comprising of three habitat types such as (i) forest (ii) riparian areas (iii) shrub grassland. we measured a range of soil characteristics that are likely to be affected by the invasion of lantana from different habitat types and also the vegetation of these habitats which are likely to be affected due to the infestation of this woody shrub. these were ph, total phosphorus, total potassium, calcium, magnesium, manganese, nitrogen, water retention capacity, organic matter content and electrical conductivity. the specific questions addressed were: 1. what is the effect of lantana invasion on vegetation and soil characteristics from the valley? 2. what is the relative importance of the three habitat types (forest, riparian area and shrub grassland) for exotic species invasion? 3. are there consistent relationships between soil characteristics and success of exotic invasives among the disturbance types? materials and methods study sites the present study was carried out in the doon valley, a part of western himalaya, india. the doon valley is surrounded by hills on all the sides and has a varied range of subtropical deciduous forests mainly dominated by shorea robusta, syzygium spp., terminalia spp., ehretia spp., and litsea spp. it is lying between latitudes 29 0 55′ and 30 0 30′ n and longitudes 77 0 35′ and 78 0 24′ e. it is a saucer shaped valley about 20km wide and 80km long with a geographical area of about 2100km 2 . the doon valley falls under the sub-tropical to temperate climate due to its variable elevation and is a part of western himalaya (fig. 3). the average maximum temperature for the doon valley was 27.65 0 c and the average minimum temperature was 13.8 0 c with average maxima in june (40 0 c) and average minima in january (1.80 0 c). the area receives an average annual rainfall of 2025.43 mm. the region receives most of the annual rainfall during june to september; the maximum rainfall was recorded in july and august. we selected six sampling sites covering all parts of the valley and divided into three habitat types i.e., forest, riparian, shrub grassland (table 1). to see the level of differences in soil properties we categorised each site into 3 types (i) control (un-invaded site), (ii) moderately invaded sites and (ii) heavily invaded sites of lantana. research methods soil was randomly sampled from the centre of the four small (1 m 2 ) subplots near the centre and at the centre of the middle plot measuring 100 m 2 after litter was removed. a hand held push probe measuring 2.5 cm diameter was used to collect soil from a depth of 15 cm below the ground surface to ensure sufficient quantity of soil was collected for subsequent analysis. ten samples were collected at non invaded, moderately invaded and highly invaded sites, which were obtained and analysed. the soil samples from moderate and highly invaded sites were collected within the lantana thickets for consistency in data capture. each soil sample was packed in a separate labelled plastic bag and transported to the laboratory for analysis. the soil samples were oven dried at 55°c for 24 h to reduce the moisture content and increase the concentration of the nutrients prior to chemical analysis. then, they were passed through a 2 mm pore sieve for homogenization before they were analyzed for various contents. soil chemical analysis air dried 2 mm sieve soil samples collected from the two studies were subjected to routine chemical analysis. total n was determined by micro kjeldahl approach and available p was determined by molybdenum blue colorimetry. exchangeable k, ca and mg were extracted using ammonium acetate, k was determined on flame photometer while ca and mg by atomic absorption spectrophotometer fig. 3 map showing western himalayan part and present study areas (doon valley) in india the role of habitat types and soil physicochemical properties… 35 (okalebo et al., 1993), ph and electrical conductivity of the soil (soil: water, 1:5) was determined by the help of water analysis kit (systronics india ltd, gujarat, india). the organic carbon of the soil was determined by walkley and black (1934) rapid titration methodas given by piper (1944). pearson’s correlation matrix, students’‘t’ test and one way anova was calculated to establish the relation between the soil parameters and the measured attributes of lantana. statistical analysis was done using xlstat v. 2011 (addinsoft, rue damremont, paris – 75018, france) for microsoft windows. biomass calculation above ground and fine root biomass (kg per sq. m.) of large colonies of lantana was recorded, for which plant roots were carefully collected using a 25×25×40 cm soil monolith within the 1m 2 quadrat. plant materials such as green material (leaves), dead residues (mulch), and roots collected were oven dried at 60 °c for 72 h and weighed. the location of each site was recorded using a global positioning system (gps) device (garmin 72, garmin, olathe, ks, usa). results all the lantana invaded sites including the moderate and high, showed considerable increase in the mean ph value. the maximum range of ph was between 7.12 (±0.40) to 7.22 (±0.24), recorded from shrub grassland type habitat and was about 1.40 % high from other moderately invaded sites of all habitat, minimum ph range was between 5.53 (±0.45) to 6.13 (±0.62), recorded from forest periphery type habitat and was about 10.84 % higher than the other moderately invaded areas (p<0.01). the moderately invaded and highly invaded areas of all the habitats recorded high ph values than the control or non invaded sites of all the habitats (table 2). the forest peripheries were situated at a comparatively higher altitude than other habitats and were found more acidic than the other two; this was explained perhaps due to fewer disturbances, free from herbivory and high altitude (952 m). the increase in ph value did not show any positive relation with the measured attributes of lantana (anova, p < 0.001). however, both increases and decreases in ph following plant invasion have been equally reported in the literature (ehrenfeld, 2003). it is not clear whether lantana prefers microsites with elevated soil ph or, in fact, it was responsible for the increase observed in this study. thus the precise soils require further study, including the contribution of its biomass parts and associated chemical contents to the change. under the lantana patch only, availability of soil base ions of ca, p, as well as carbon and ec correlated significantly and positively with increasing ph (r=0.74, 0.69, 0.78, 0.84, respectively; p<0.05, n=30), while s and fe showed the opposite pattern (r=−0.89, −0.73, respectively; p<0.05, n= 30). macronutrients measured in this study (mg, ca, k, p and n) showed significant differences between the moderately invaded, highly invaded and un-invaded sites (anova, p < 0.05), except carbon concentrations which did not differ between all sites (anova, p = 0.673) (table 1). the macronutrients among the different habitat types such as the forest, riverine and shrub grassland habitats also strongly and significantly differed (anova, p < 0.001) except carbon concentrations which did not show significant variations across habitats (anova, p = 0.376). further, when the possible relationship between the habitat type and invasion pattern was analysed (si × ha level interaction), the ca, k, n and p concentrations were found highly significant (anova, p < 0.001) while mg and s was found less table 1 site characteristics of doon valley with dominant invasive species name of the sites dominant species point coordinates elevation (m) habitat type sahastradhara lantana camara l. 30 0 23′ 08.17″ n, 78 0 07′ 53.81″ e 889 riparian areas adhatoda zeylanica l. parthenium hysterophorus l. asarori riparian area parthenium hysterophorus l. 30 0 17′ 10.40″ n, 78 0 03′ 22.27″e 629 riparian areas lantana camara l. ageratum conyzoides l. chandrabani forest periphery lantana camara l. 30 0 15′ 26.03″ n, 78 0 00′ 29.45″ e 893 dense forest opuntia dillenii ker gawl. adhatoda zeylanica l. rajpur forest periphery lantana camara l. 30 0 23′ 02.83″n, 78 0 05′ 09.93″ e 952 dense forest murraya koenigii (l.) spreng. parthenium hysterophorus l. mothronwala parthenium hysterophorus l. 30 0 15′ 22.81″ n, 78 0 01′ 42.46″ e 532 shrub grassland lantana camara l. ageratum conyzoides l chromolaena odorata l. jolly grant lantana camara l. 30 0 11′ 17.16″ n, 78 0 11′ 17.91″ e 561 shrub grassland arundinella spicata dalzell. ageratum conyzoides l parthenium hysterophorus l. 36 mandal and joshi (2014) significantly different (anova, p = 0.028; p = 0.039, respectively). carbon concentration was not significantly different (anova, p=0.395) with regard to the interaction level of site and habitat (si × ha) interaction. except for silt which was not significantly different between highly invaded, moderate and un-invaded sites (anova, p=0.966), the values of ph, conductivity, sand and clay recorded significant differences at site level interaction (anova, p < 0.05) but they were non significant when calculated for both site versus habitat level interaction (anova, p=0.452) (table 2). on the other hand, ph, conductivity, sand and silt recorded strong significant variations across the forest, riparian and shrub grassland habitats (anova, p < 0.001) while clay recorded less significant difference (anova, p=0.237). at the invasion verses habitat interaction level (si × ha level interaction), significant differences were recorded in ph (anova, p≤ 0.05) while across sites, conductivity, sand, silt and clay did not vary significantly (anova, p > 0.05). the macronutrient concentrations of mg, mn, p, n ca and k measured in this study were also found to be higher in heavy invaded sites than moderate and un-invaded ones (table 2). the anova results also supported this findings that plots from where the neighbouring plants were removed and only left with lantana, nitrogen availability significantly increased, indicating that the neighbouring plants reduce the nitrogen availability and by the result it is clearly indicated that exotic and invasive plant like lantana increases the total nitrogen content in the adjoining soil where they grow (anova, p < 0.001) (table 3). species diversity and richness varied significantly among the three levels of lantana infestation as revealed by the shanon wiener index of diversity (h') and species richness (s) [f=9.982, p<0.05, f=24.33, p<0.05 respectively]. the un-invaded category had the highest species diversity and species richness followed by the moderately invaded and highly invaded. the principal component analysis (pca) of all the soil parameters and the calculated attributes of lantana are shown in (fig. 4) respectively. in pca 1 for soil parameters the eigen values for both f1 and f2 axes were 34.13 and 30.93 respectively, representing 65.05% of the cumulative variance of soil data. the first principal component was related to k, n, ca, ph and sand while the second principal component was mainly related to conductivity, silt and soil ph. the pca shows that soil parameters like ph, available p and k, represent ne table 2 mean soil chemical and physical properties by site type. p -values are from t-tests comparing the properties by site type (c.v. stands for coefficient of variation, and is provided as a percentage, sd: standard deviation, ns = non significant,* p<0.05, *** p≤0.001) soil property control (non invaded) moderately invaded heavily invaded p value site habitat type si × ha (interaction level) mean sd c.v. mean sd c.v. mean sd c.v. bulk density (gm/cm 3 ) 0.97 0.16 16.5 1.1 0.15 13.6 1.6 0.23 14.2 < 0.001 *** * *** cec (meq/100cm 3 ) 4.9 1.28 26.1 7.8 2.8 35.9 8.1 1.3 34.7 < 0.001 *** *** *** base saturation (%) 58 14.52 25 84 11.96 14.2 87 10.22 13.9 < 0.001 *** ns ns ph 6.19 0.37 7.4 6.34 0.61 10.3 6.78 0.61 10.3 < 0.001 *** *** *** p (mg/dm 3 ) 8.7 2.6 29.9 14.9 7.25 54.12 16.34 8.21 55.1 < 0.001 *** *** * ca (mg/dm 3 ) 383 219.68 57.4 936 457.12 45.21 1044 481.88 41 < 0.001 *** *** * mg (mg/dm 3 ) 162 77.74 48 102 43.44 42.6 100 72.13 44.21 < 0.001 *** *** ns zn (mg/dm 3 ) 2.8 1.51 53.9 13.24 15.23 97.6 15.6 16.23 96.33 < 0.001 *** *** ns cu (mg/dm 3 ) 1.1 0.38 34.5 3.8 2.68 70.5 3.98 2.78 73.21 < 0.001 *** *** ns fe (mg/dm 3 ) 703 3.12 24.5 531 3.66 28.8 459 3.68 28.8 < 0.001 *** *** ns na (mg/dm 3 ) 19 4.03 26.9 17 4.23 42.2 16 3.21 42.2 < 0.001 *** *** *** mn (mg/dm 3 ) 52.4 27.08 51.7 42.18 15.33 37.43 38.7 14.15 36.6 < 0.001 *** *** *** humic matter (%) 0.38 0.11 28.9 0.32 0.21 65.6 0.32 0.21 65.6 < 0.001 *** *** * weight per volume (g/cm 3 ) 1.02 0.07 6.9 1.04 0.1 9.6 1.04 0.1 9.6 < 0.001 *** ns ns k (mg/dm 3 ) 62 24.29 39.2 66 25.75 39 66 25.75 39 < 0.001 *** *** * s (mg/dm 3 ) 18 3.75 26.8 15 2.67 67.9 13 2.06 67.9 < 0.001 *** * ns clay (%) 17.12 4.49 44.9 16.33 5.86 53.3 15.88 5.86 53.3 < 0.001 *** ns ns sand (%) 46.12 9.65 13.1 48.11 12.08 16.7 49.21 12.08 16.7 < 0.001 *** ns ns silt (%) 37.13 6.78 40.01 35.79 8.21 48.6 35.34 8.21 48.6 < 0.001 *** *** ns lantana cover (%) 0 (± 2.92) 35 (± 2.01) 85 (±3.01) < 0.001 the role of habitat types and soil physicochemical properties… 37 gative correlation with other soil parameters (r = –0.042 with p, 0.109 with k, –0.009 with n and 0.0624 with c). the analysis revealed that the pri ncipal components were sufficient in explaining the variation of the soil properties between the highly invaded, moderate and un-invaded sites in doon valley. after correlation, the results were subjected to an ordination biplot, which revealed that the sites separated into clusters based on the sites and their measured properties. many of the macro nutrients ratio were showing negative correlation with diffe rent calculated attributes but total nitrogen and carbon contents were represented as the key factor for d eciding the different shrub attributes and thereby co ntributing strongly in the total shrub level biomass calculation. fig. 4 pca ordination for soil properties from different habitats (i = invaded sites, c = control or un-invaded sites) discussion the moderately invaded plots and the highly invaded plots were located close to the selected invaded patches, being separated only by a few meters. moreover, preliminary field observations and samples analyse (e.g., texture and cationic exchange capacity) showed that soils of moderate and no invasion areas differ significantly from the highly invaded areas except few. it should also be noted that lantana patches are incessantly escalating in doon valley but other opportunistic species such as chromolaena odorata, parthenium hysterophorus, cassia tora, cassia occidentalis, urena lobata, ipomoea carnea, sida acuta and solanum torvum and their growth is still restricted to some specific areas and specific geographical conditions. the ph amongst other parameters was found to be a significant factor deciding only the coverage of lantana. in shrub grassland and riverine areas, we found that ph is slightly less acidic to neutral and recorded a little difference between moderate invasion and high invaded sites. however, the less acidic condition favoured lantana to grow better in these habitats than the forest (site data of this study). the density of lantana in shrub grassland was found highest (21,800 ha -1 ) with a maximum biomass of (1.356 kg m -2 ) followed by another highly disturbed area the riparian zone where the ph was slightly changed from less invaded areas to invaded areas i.e., from 7.12 (±0.40) to 7.22 (±0.24) which was again a neutral to basic condition and found favouring the lantana growth with a density of 20,340 ha -1 and biomass (1.296 kg m -2 ). the increased ph from all the highly invaded sites and even from the moderately invaded sites were found to have a strong positive correlation with the coverage and total shrub density (r= 0.89). the similar change had been recorded from a dry deciduous forest of india (sharma and raghubanshi, 2011). table 3 two way anova results for the vegetation characters, disturbance types and soil properties. ( df = degrees of freedom, f = fisher’s statistic value , p value = null hypothesis) factor variables d.f. f p value habitat type native species richness 3, 32 22.45 <0.001 exotic species richness 3, 32 63.98 <0.001 percentage cover of native species 3, 32 55.38 <0.031 percentage cover of lantana 3, 32 23.33 <0.001 lantana density (ha -1 ) 3, 32 19.46 <0.001 lantana height 3, 32 18.55 <0.001 disturbance type native species richness 3, 32 4.89 <0.013 exotic species richness 3, 32 13.55 <0.001 percentage cover of native species 3, 32 5.89 <0.001 percentage cover of lantana 3, 32 30.12 <0.021 lantana density (ha -1 ) 3, 32 23.34 <0.001 lantana height 3, 32 20.03 <0.005 soil properties native species richness 3, 32 34.22 <0.001 exotic species richness 3, 32 56.34 <0.001 percentage cover of native species 3, 32 49.56 <0.001 percentage cover of lantana 3, 32 31.24 <0.002 lantana density (ha -1 ) 3, 32 23.22 <0.001 lantana height 3, 32 15.35 <0.001 38 mandal and joshi (2014) all the moderate and highly invaded areas showed the elevation in soil macronutrients including n, p, k, ca, mg, mn, and took up about twice as much of these macronutrients per unit area as the native plants. this may explain the higher proportion of these above mentioned soil macronutrients fraction in invaded patches. the availability of these macron utrients in the highly invaded soil was recorded much higher than their control i.e., non invaded sites, this clearly indicates that lantana invaded areas have more n, p, k, ca, mg, mn, than less invaded or the places where lantana infestation is negligible and surely this increased level of these macronutrients strongly favoured in increasing their coverage and biomass. different attributes like plant height, stem diameter, canopy area and phytovolume were also found directly related to the availability of soc and total n. soil organic carbon (soc) and the total nitrogen (n) had a direct impact in determining the coverage of lantana and biomass (table 4). an increase in soil organic carbon (soc) content under stands of invasive plants had been reported in many previous studies (fickbohm and zhu, 2006; heneghan et al., 2006), and had also been attributed to increase biomass production and litter fall (yelenik et al., 2004) or to reduce litter decomposition rates (ogle et al., 2004).the soc and total n was considerably increased in all the highly invaded sites from all habitat types. the increase in nitrogen and phosphorus levels with increase in lantana intensity could be due to detable 4 summary of regression analysis of different sites for soil parameters and its relation with shrub's measured and calculated attributes measured and calculated parameters source of variation ss df ms f p organic carbon (%) vs avg. plant height (cm) between groups 337346.06 1 337346 90.7557 0.032 within groups 52039.074 14 3717.08 total 389385.14 15 nitrogen (%) vs avg. plant height (cm) between groups 341657.79 1 341658 91.9226 0.001 within groups 52035.19 14 3716.8 total 393692.98 15 avg. height (cm) vs avg. crown diameter between groups 67606.5 1 67606.5 17.5285 0.091 within groups 53997.22 14 3856.94 total 121603.72 15 nitrogen (%)vs avg. plant height (cm) between groups 105301.87 1 105302 750.756 0.102 within groups 1963.6553 14 140.261 total 107265.53 15 organic carbon (%)vs avg. crown diameter between groups 102914.24 1 102914 732.285 0.001 within groups 1967.5395 14 140.539 total 104881.78 15 organic carbon (%)vs avg. shrub canopy area (m 2 ) between groups 0.6102344 1 0.61023 1.45873 0.024 within groups 5.8566423 14 0.41833 total 6.4668767 15 nitrogen (%)vs avg. shrub canopy area (m 2 ) between groups 8.5195394 1 8.51954 60.47 0.0000 within groups 1.9724423 14 0.14089 total 10.491982 15 nitrogen (%)vs canopy coverage (ha -1 ) between groups 633273.41 1 633273 134.029 0.001 within groups 66148.655 14 4724.9 total 699422.06 15 organic carbon (%)vs canopy coverage (ha -1 ) between groups 627398.29 1 627398 132.778 0.021 within groups 66152.539 14 4725.18 total 693550.83 15 organic carbon (%) vs phytovolume (m 3 ha -1 ) between groups 5.669324 1 5.74352 55.1941 0.011 within groups 1.438345 14 1.26653 total 7.107233 15 nitrogen (%)vs phyto volume (m 3 ha -1 ) between groups 5.669234 1 5.73442 55.1958 0.021 within groups 1.438455 14 1.22371 total 7.107366 15 organic carbon (% )vs biomass m -2 (kg) between groups 10.800708 1 10.8007 28.7303 0.011 within groups 5.2630903 14 0.37594 total 16.063798 15 the role of habitat types and soil physicochemical properties… 39 crease in nutrient impounding followed by the displacement of native species or reduction in their recruitment and growth rates, also lantana drops a large amount of litter beneath it, this could probably the reason for elevated nitrogen and phosphorus levels in all invaded sites (findings of this study). these findings are consistent with some findings where an increase in soil nitrate followed by lantana invasion was recorded. according to this result nitrogen mineralization and nitrification commonly increase in response to invasions (ehrenfeld, 2003); this could further explain the increase in available nitrogen that was recorded from the different study sites. n availability in soil is often increased under invasive plants, but reduced n availability has also been found, for example bromus tectorum in arid grassland in the western usa (evans et al., 2001). the latter effect was typically attributed to the production of nutrient poor litter, leading to slower n mineralization (drenovsky and batten, 2007). the highest soc (%) was recorded from riparian areas with highest average lantana height, average stem diameter and the lowest was recorded from shrub grassland type habitat which was from 0.98 (±0.47) to 1.28 (±0.23) with an average lantana height of (210cm). these two attributes were found very strong factors in the biomass calculation of shrub (r=0.88) when analysed in the regression model in some studies (mandal and joshi, 2014). plant height was not found significantly correlated with the availability of soc (%) and total n (%) (r=0.47) and (r=0.57) respectively, but when biomass as a whole taken into account these two soil parameters gave a strong positive correlation (r=0.91) and (r=0.92) respectively (mandal and joshi, 2014). in forest habitat the height of the shrub was found unexpectedly higher than other habitats, this was explained due to the enormous power of lantana to compete with the native species for natural resources like sunlight, as lantana is a photophilous (growing best in strong light) plant, and in closed canopy forest areas it competes with the native trees in order to get more sunlight, this finding was also supported by the earlier study conducted by sharma and raghubanshi (2011). both soc (%) and total n (%) showed very strong positive correlation while taken as a variable to measure the crown diameter of lantana (r=0.94) and (r=0.98) respectively. not all the soil carbon is associated with organic material; there is also an inorganic carbon component in soils which is of particular relevance to dry lands because calcification and formation of secondary carbonates is an important process in arid and semi arid regions. dynamics of inorganic carbon pool are poorly understood although it is normally quite stable. differences in litter fall mass interact with differences in the litter decomposition rate to affect the net flux of c into the soil. many exotic plants have more rapidly decomposing litter than the natives. decomposition rate may vary with plant tissue, so that differences in plant morphology ultimately control litter dynamics. these results clearly indicates that soil attributes like soc, total n, p, k and soil textures play a vital role in the growth of lantana in a subtropical deciduous condition like doon valley. however, the present results clearly revealed that riparian habitat recorded maximum coverage and biomass of lantana followed by grass land and forest habitat. the reason for riparian habitat receiving more coverage and biomass is probably due to the significant change in the soil attributes, open areas and heavy tourist activities. soil moisture, potassium, nitrogen, soil organic carbon and phosphorus levels varied significantly among these habitats from control to heavy infested areas. soil nitrogen, soil organic carbon, phosphorus and potassium levels increased with increase in lantana density. altitude, soil texture and soil depth are unlikely to change significantly following lantana invasion. as a result, the insignificant difference in these variables among the two categories would indicate the homogeneity of the environment. this was supported by the study where disturbance by gophers can be the important factor in the invasion of serpentine grassland by bromus mollis and other non-native annual grasses following years of above average rainfall (hobbs and mooney, 1991). in some studies it was found that soil texture is a useful indicator of soil permeability, soil water rete ntion capacity, and soil capacity to retain cations and influences plant available moisture and plant available nutrients (white, 1997). some workers considered clay content as an index of nutrient availability (scholes and walker, 1993). the greatest influence of ph on plant growth is its effect on nutrient availabi lity. since the result for moisture and nutrients (soil depth, and texture) did not vary significantly with increase in lantana intensity. it follows that changes in nutrient levels observed could be attributed to lantana invasion effects. differences in plant species composition reflect difference in soil water and nutr ient availability (scholes, 1990a), and changes caused by lantana in the soil can be translated into plant composition. the increase in nitrogen and phosphorus levels with increase in lantana intensity could be due to decrease in nutrient sequestration following native species displacement or reduction in their recruitment and growth rates. decrease in soil moisture with i ncrease in lantana intensity shown by this study could be accounted for by the fact that lantana is a short rooted plant, which maximises use of moisture on top layers of the soil, from which soil samples were collected. furthermore, lantana is very efficient in moisture sequestration leading to reduction in the soil availability of moisture. with increased growth rate, lantana propagates splendidly, which, as verified in this study results into changes in species composition and soil properties. the structural design of lantana growth is such that it prevents light penetration to the ground. resul ting in noticeable heterogeneity in terms of light avai lability beneath the lantana bush and affects species diversity underneath its canopy (fig. 5). light availability on the forest floor has already been recognized by many researchers as a key factor that influences 40 mandal and joshi (2014) fundamental character in propagating exotic species (jones et al., 1994; walters and reich, 1996). the dense cover created by upright stratification of lantana may reduce the strength or duration of light under its canopy and thus decrease the cover of plants sp ecially the herbs. this could be explained due to the formation of a light regime which is photosynthetically inactive and situated at ground level (fetcher et al., 1983; turton and duff, 1992). it is most likely that herbs are directly influenced by the amount of light reaching to the forest floor, and due to the non availability of light to the ground level because of heavy lantana invasion in many habitats especially the riparian habitat the herbaceous cover is declined. this could also be the possible reason in the decline of tree seedlings and the herb flora, this finding was advoc ated by the findings of sharma and raghubanshi (2006, 2007). the current results are also in agreement with (ehrenfeld, 2003) who documented that soil moisture can either increase or decrease following invasion. these findings where lantana was foundreducing moisture levels are also consistent with the findings by hiremath and sundaram (2005) who found that lantana affects water supply negatively. fig. 5 photos of lantana camara taken from the different habitats chosen for this study. [the letters represent different habitat types, such as a, b & c= forest peripheries, d & e = shrub grassland and f, g & h = riparian habitat] conclusions the present study had provided strong evidence that lantana invasion is reducing biodiversity and negatively affecting other ecosystem processes in doon valley and possibly in other nearby areas of its occurrence. in conclusion it is clear from the present findings of this study and the past literature that the invasion of all three habitats including forest communities, riparian areas and the shrub grassland by woody plant invaders, such as lantana camara, adversely affects the vascular plant species diversity by reducing species richness and abundance, in turn altering species compositions. there is also a remarkable change in the soil nutrient property in all the highly invaded areas of doon valley from its adjacent areas which are either moderately invaded or not invaded by lantana, this change is not only maximizing the uptake of these soil macronutrients by other opportunistic species but also favouring the further utilization of these nutrients by lantana for its own growth. administration and management of l. camara can diminish such adverse effects by facilitating the establishment of native juvenile species to increase species richness. however, management cannot restore species compositions, at least in the short term unless we understand the right factors that influence the distribution of lantana and also initiate continuous monitoring of native forest regeneration following plant invader management, which can prevent secondary weed invasion and indicate whether long term habitat restoration can occur. acknowledgements we are thankful to the department of botany and national forest library, icfre, dehradun for providing both laboratory and library facilities. we extend our thanks to the department of botany, dav (pg) college, dehradun for providing the laboratory and statistical facility. we also thank apex laboratory services, dehradun, india for assisting in the soil analysis. references agrawal, a. a., kotanen, p. m., mitchell, c.e., power, a. g., godsoe, w., klironomos, j. 2005. enemy release? an experiment with congeneric plant pairs and diverse above – and below ground enemies. ecology 86, 2979–2989. doi: 10.1890/05-0219 bhagwat, s.a., breman, e., thekaekara, t., thornton, t.f., willis, k.j. 2012. a battle lost? report on two centuries of invasion and management of lantana camara l. in australia, india and south africa. plos one 7(3), e32407. doi: 10.1371/journal.pone.0032407 bone, r., lawrence m., magombo, z. 1997. the effect of a eucalyptus camaldulensis (dehn) plantation on native woodland recovery on ulumba mountain, southern malawi. forest ecology and management 99, 83–99. doi: 10.1016/s0378-1127(97)00196-5 bray, s.r., kitajima, k., sylvia, d.m. 2003. micorrhizae differentially alter growth, physiology and competitive ability of an invasive shrub. ecological application 13, 565–574. doi: 10.1890/10510761(2003)013[0565:mdagpa]2.0.co;2 brooks, m.l., d'antonio, c.m., richardson, d.m., grace, j.b., keeleu, j.e., ditomaso, j.m., hobbs, r.j., pellant, m., pyke, d. 2004. effects of invasive alien plants on fire regimes. bio science 54, 677–688. doi: 10.1641/00063568(2004)054[0677:eoiapo]2.0.co;2 chatanga, p. 2007. impact of alien invasive species lantana camara l. on native vegetation in northern gonarezhu national park, zim the role of habitat types and soil physicochemical properties… 41 babwe. msc thesis, department of biological sciences, university of zimbabwe. pp. 22 cheal, d., coman, b., robley, a. 2006. pest plants and animals. in: attiwell, p., wilson, b. 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environmental geography 9 (1–2), 39–44. doi: 10.1515/jengeo-2016-0006 issn: 2060-467x constraining the age of floodplain levels along the lower section of river tisza, hungary györgy sipos*, tímea kiss, orsolya tóth department of physical geography and geoinformatics, university of szeged, h-6722, egyetem u. 2-6, hungary *corresponding author, e-mail: gysipos@geo.u-szeged.hu research article, received 22 april 2016, accepted 2 july 2016 abstract during the late pelistocene-holocene transition the fluvial landscape of the great hungarian plain changed considerably as a consequence of tectonic, climatic and geomorphological factors. geochronology, and especially luminescence dating, is a very important tool in reconstructing these changes. the present study focuses on the lower-tisza region and addresses the timing of the development of different floodplain levels. in the meantime the luminescence characteristics of the investigated alluvial sediments were also assessed, with a special emphasis on the comparison of silty fine grain and sandy coarse grain results, as in the given medium and low energy environment fine grain sediments are more abundant, however, based on the literature, coarse grain samples are more reliable in terms of luminescence dating. measurements were performed on 12 samples originating from the point bars of two large palaeo-meanders, representing different floodplain levels along the river. results indicate the applicability of both grain size fractions for dating purposes, though fine grain subsamples overestimate in average by 1.5 ka the ages yielded by coarse grain subsamples. consequently, fine grain samples can be used for outlining only general trends, and resul ts need to be controlled by coarse grain measurements where possible. based on the ages received, the upper floodplain was actively formed until 13-15 ka, when incision and the development of an intermediate floodplain level started. the meander on the intermediate flood plain level developed then very actively until 9 ka. as indicated by the received age information the intensity of meander formation could be highly affected by climatic and especially vegetation control. however, reconstruction can be refi ned later by further sampling and the application of the results of the present paper. keywords: osl, alluvial sediments, river tisza, palaeo-fluvial record introduction the primarily alluvial environment of the great hungarian plain hosts numerous generations of palaeochannels which developed in response to highly varying water and sediment discharges during the late pleistocene and holocene (gábris and nádor, 2007; kiss et al., 2015). in several cases these channels are located on well identifiable floodplain levels, referring to incision governed by either tectonic or climatic processes. the evolution of the fluvial network, and especially the development of the tisza has been addressed by several earlier studies (e.g. somogyi, 1967; gábris, 1986; borsy, 1989, kiss et al., 2013), focusing on its palaeo-discharge, pattern changes or the age of certain channel generations. a key question of fluvial development along the lower tisza, affected by tectonic subsidence (nádor et al., 2007), is the morphology and separation of different floodplain levels. kiss and hernesz (2011) and later kiss et al. (2012) identified two separate levels: a higher and a lower floodplain. the later has several meander cores or umlaufbergs being the remnants of the preincision floodplain surface. based on optically stimulated luminescence (osl) data, they put the start of incision earlier than 20.1±2.1 ka and the termination of it to 8-9 ka. more recently by extending the morphological analysis to the serbian section of the river hernesz (2015) separated a further, intermediate floodplain level as well. the dating of palaeochannels on these floodplain levels was carried out by using osl on coarser sand sized, but also on fine grain silty sediments, however the comparability of results has only been partly assessed (hernesz, 2015). a major underlying principle of osl dating is that sediment grains during transportation are exposed to sunlight, which resets the osl signal to zero. consequently, during laboratory measurements the time elapsed since the last exposure to light, or in other words the time of deposition can be determined. in certain sedimentary environments however resetting is not always complete, which results in partial bleaching, making measured osl ages higher than the true age. fluvial deposits are greatly affected by the phenomenon. previously, several researches addressed the role of grain size in the bleaching process (hu et al., 2010; vandenberghe et al., 2007; alexanderson, 2007). most of them concluded that coarser grains (sand) are more suitable for luminescence dating than finer grains (silt), as resetting is more adequate in their case. this is explained 40 sipos et al. (2016) by the possible coagulation of fine grains (hu et al., 2010) and the more frequent exposure of coarser grains on bar surfaces (rittenour, 2008). the most common minerals used for osl dating are quartz and feldspar. although both minerals are applicable, the choice depends on various factors. quartz saturates at lower doses, but on the other hand feldspars suffer from anomalous fading (vandenberghe, 2004). in summary most of the researches emphasize that in terms of fluvial sediments with an age up till several 10 ka the most confident luminescence ages can be received if coarse grain quartz is applied (bøtter-jensen, 2006). the primary aim of the present research was to investigate the development time of two floodplain levels along lower tisza by using osl. another goal was to assess the rate of morphological evolution in case of the studied palaeomeanders, which provides valuable additional information on the environment in which they were developing. furthermore, the investigations also allowed to test the luminescence characteristics of alluvial sediments in the region and to compare ages retrieved from the fine grain and coarse grain fraction of osl samples, since in many situations, as a consequence of the medium energy environment only silty sediments are available for dating. study area our research focused on the lower tisza basin where palaeomenaders remained recognizable only in a relatively narrow n-s belt along the tisza river (fig. 1). the width and wavelength of these channels significantly exceed contemporary values even if compared to that of the danube. two major channel generations were investigated (fig. 2): one located on the higher floodplain level (site1), having larger but more blurred pointbars and main channel (meander wavelength=25 km, width=1000 m), and another lying on the intermediate level (site 2), being smaller but having much intense forms (meander wavelength=9.2 km, width=500 m). the elevation difference is around 1 m between the two floodplain levels. fig. 1 location of the studied meanders, the border of the lower and upper floodplain surfaces, and situation of intermediate floodplain levels based on hernesz (2015) fig. 2 geomorphology of the study sites and the location of the drillings methods the age and development rate of meanders were determined by the means of luminescence dating (osl). 10 drillings were made to sample pointbar and channel sediments of two megameanders (fig. 2). fluvial stratigraphy and sedimentological correlations were set up by laser grainsize analysis (fritsch analysette 22 microtec plus). osl samples were taken from layers with increased sand content, using drilling and undisturbed steel cylinders. in all 12 sediment samples were measured by osl. samples were mainly silty, but usually containing an adequate amount of sand for dating, therefore where it was possible the polymineral fine grain and quartz coarse grain fractions were dated simultaneously in order to assess the adequacy of different materials for dating purposes. the preparation of the samples has followed usual laboratory techniques (aitken, 1998; mauz et al., 2002). for coarse and fine grain dating the 90-150 μm and the 411 μm fractions were used, respectively. the separation of fractions was made by sieving and settling. the carbonate and organic material content was removed by repeated treatment in 10% hcl and 10% h2o2. in case of coarse grains, a na-polytungstanate (lst fastfloat) heavy liquid separation was applied for the separation of the quartz fraction. this step was followed by a 50 min etching in 40% hf, aiming at removing any remaining feldspar contaminations and the outer layer of quartz for dosimetry constraining the age of floodplain levels along the lower section of river tisza, hungary 41 reasons. coarse grains were adhered to stainless steel discs by silicone spray (2 mm mask), fine grains (2 mg/aliquot) were settled to aluminium discs by using acetone. a number of aliquots were prepared for luminescence tests and for equivalent dose (de) determination. measurements were made using a risoe da-15 tl/osl luminescence reader by applying the sar (wintle and murray, 2006) and dsar (roberts and wintle, 2001) protocols on the coarse grain sand and the fine grain silt fraction, respectively. in terms of fluvial samples usually the sand sized quartz fraction is investigated, assuming that it usually has more chance for complete bleaching during sediment transport. in this case comparative measurements were made to test the applicability of the fine grain component too. concerning the coarse grain fraction a combined preheat-cutheat test was used for determining optimal heating parameters during the sar measurements. preheat temperatures varied between 200 oc and 260 oc, while cutheat temperatures between 140 oc and 220 oc. in case of fine grain samples a simple preheat test was applied, with a constant cutheat at 160 °c. during the tests sar recycling ratios (ratio of two sensitivity corrected luminescence signals generated by identical regeneration doses) and recuperation (thermal and photo transfer of electrons to osl traps) values were monitored to determine the best thermal treatment. subsequently, known doses were administered to 5-5 aliquots of each sample and a sar measurement was run in order to determine the given dose/measured dose ratio (dose recovery test), which is a robust test for assessing the applicability of the sar procedure. known doses were set to be close to the preliminary de, assessed prior to any of the tests. sar measurements were performed on 24-48 aliquots, standard rejection criteria were used to select those aliquots performing well during the measurements (recycling ratio being within 1.00 ± 0.05, de error being lower than 10%, recuperation being lower than 5%). single aliquot de values were analysed using the central age and the minimum age models (galbraiht, 1999) in case of coarse grain and fine grain samples, respectively. environmental dose rate (d*) was determined by using high-resolution, extended range gamma spectrometry (canberra xtra coaxial ge detector), using 500 cm3 marinelli beakers. dry dose rates were calculated using the conversion factors of adamiec and aitken (1998). wet dose rates were assessed on the basis of in situ water contents. the rate of cosmic radiation was determined on the basis of burial depth following the method of prescott and hutton (1994). fig. 3 results of a combined preheat-cutheat and dose recovery test of a coarse grain quartz sample (osz245). a) dose recovery ratio; b) recycling ratio and recuperation fig. 4 preheat and dose recovery test of polymineral fine grain samples. a) de at various preheat temperatures, b) the dose recovery ratio values of several fine grain samples, c, d, e) recycling ratio and recuperation of samples indicated on fig. 4a, colours are identical 42 sipos et al. (2016) results and discussion looking at the thermal tests in general, as it was expected, coarse grain samples showed a much higher scatter in terms of sar internal check para meters and also in terms of dose recovery ratios than fine grain samples (fig. 3 and fig. 4). concerning recuperation coarse grain samples performed fairly well up till a preheat temperature of 260-280°c (fig. 3), thus this parameter has not seemed to be problematic in terms of final measurements. however, recycling ratios were rather poor at almost each preheat-cutheat combinations. acceptable results were received at either the 240°c/160°c (fig. 3) and the 220°c/160°c combinations. at these temperature settings dose recovery was also within thresholds (fig. 3). meanwhile, in case of fine grain samples a high stability of equivalent doses was observed at various preheat temperatures, and the recovery of artificial doses was also very precise (fig. 4). recycling ratios remained close to unity and recuperation was also insignificant (fig. 4). as a consequence of the above during the final sar measurements, aiming at determining de, 40-50 % of aliquots had to be rejected in terms of coarse grain quartz samples during the age analysis. however, by applying even stricter rejection criteria for fine grain samples 95 % of results were still applicable. following age calculation fine grain results were relatively close to coarse grain result (table 1, fig. 5). significant overestimation was experienced in three cases, on the other hand three other fine grain ages were practically identical to their coarse grain equivalent (fig. 5). the mean overestimation related to fine grain ages was 1.5 ka, meaning that general trends might be inferred from fine grain fluvial data in the region, and major channel generations can be separated, but the date of shifts and changes can hardly be determined without the use of coarse grain data. fig. 5 coarse grain and fine grain ages plotted against each other in case of samples where both were determined based on coarse grain derived ages, the point bars related to the upper floodplain meander (site 1) started to develop 14-16 ka ago, and were probably formed up till 13-15 ka. going closer to the palaeochannel, a less elevated bar (drilling c) yielded a coarse grain age of 12.4±1.4 ka at a 2.6 m depth, which is in good correspondence with the topmost sample of drilling b with an age 13.3±1.6 ka (fig. 6). consequently, a second phase of channel formation is suggested at this time, which was also accompanied by a slight incision, as the point bar sequence can be separated into two levels (fig. 6). at a 1.4 m depth however, an age of 7.8±1.0 was received, which is very young compared to previous results and might indicate either post formational aggradation, or a next phase of channel development. nevertheless, this can only be confirmed if further drillings are made closer to the channel. table 1 dose rate, equivalent dose and age data of the investigated samples sample depth (m) u (ppm) th (ppm) k (%) d*(90-150 µm) (gy/ka) d*(4-11 µm) (gy/ka) de (90-150 µm) (gy) de (4-11 µm) (gy) age (90-150 µm) (ka) age (4-11 µm) (ka) site 1 osz255 1.4 2.53±0.24 9.28±1.04 1.73±0.17 2.72±0.14 3.21±0.14 21.14±2.53 27.73±0.30 7.8±1.0 8.6±0.4 osz257 2.6 2.60±0.21 9.42±1.05 1.85±0.09 2.64±0.10 3.11±0.13 32.70±3.37 46.9±0.78 12.4±1.4 15.1±0.7 osz258 1.1 2.43±0.20 8.85±1.00 1.62±0.08 2.68±0.11 3.18±0.14 39.03±4.39 41.99±0.69 14.5±1.8 13.2±0.6 osz260 2.6 2.27±0.15 8.20±0.82 1.54±0.07 2.37±0.09 2.80±0.12 36.96±4.09 44.25±0.57 15.6±1.8 15.8±0.7 osz262 2.1 2.82±0.23 10.65±1.17 1.90±0.09 2.93±0.11 3.48±0.14 44.59±4.64 53.74±0.79 15.2±1.7 15.5±0.7 site 2 osz242 1.4 2.55±0.20 9.44±1.04 1.59±0.08 3.43±0.16 37.91±0.67 11.1±0.5 osz244 1.6 2.47±0.17 8.33±0.86 1.42±0.07 3.12±0.15 42.14±0.62 13.5±0.7 osz245 1.0 1.74±0.15 6.28±0.74 1.11±0.06 1.99±0.10 2.35±0.13 19.8±2.56 22.74±0.57 10.0±1.4 9.7±0.6 osz246 1.3 1.74±0.15 6.28±0.74 1.11±0.06 2.00±0.10 2.37±0.13 18.23±2.34 27.46±0.23 9.1±1.3 11.6±0.5 osz247 2.0 2.15±0.17 7.86±0.86 1.35±0.06 2.74±0.13 33.98±1.1 12.4±0.7 osz248 1.5 2.64±0.21 8.38±0.96 1.48±0.07 3.17±0.15 32.99±0.43 10.4±0.5 osz254 2.2 2.43±0.19 8.34±0.94 1.37±0.07 2.34±0.10 2.80±0.13 20.98±2.59 36.15±0.60 9.0±1.2 12.9±0.6 constraining the age of floodplain levels along the lower section of river tisza, hungary 43 concerning site 2 both coarse grain and fine grain data indicate that the point bar sequence developed relatively intensively between 11 ka and 9 ka, thus one continuous phase of development can be identified. consequently, lateral development was much faster than in case of the meander on the upper floodplain. age data indicate that the intermediate floodplain level developed right after the second development stage (at 12-13 ka) of the upper floodplain meander, thus a continuous incision process can be hypothesised during the pleistoeneholocene transition. the difference in the dynamics of meander evolution can partly be explained by changing palaeoenvironment and discharge values. the first phase of evolution on the upper floodplain can be related to a high discharge period during the bølling-allerød interstadial as observed at other sites by gábris and nádor (2007) and kiss et al. (2015). nevertheless, a relatively low intensity of development is inferred, which may refer to the significance of vegetation control under a warm and humid climate. the second phase and the start of the incision process can be related to the younger dryas, which obviously brought much lower discharges and although vegetation control was limited also, meander development was slow. this might also be caused by the fact that the major tributary of the tisza (river maros) shifte d its course frequently in the region at this time (sümeghy et al. , 2013, kiss et al., 2015). the slight younger dryas incision, however, underlies the importance of tectonic forcing over climatic control in the development of floodplain levels along the river. on the other hand, during the development of the intermediate floodplain level, fluvial processes accelerated suddenly in the preboreal, as it is resembled by the data of site 2. in this case large discharges as a matter of glacier melting and fairly low vegetation control can explain intense meander formation. conclusions based on the tests, both coarse grain and fine grain samples have adequate properties for the application of luminescence dating on fluvial sediments in the lower tisza region. nevertheless, coarse grain samples have poorer characteristics, and therefore extensive measurements are required to have sufficient number of aliquots passing the rejection criteria. according to the comparative analyses, the resetting of fine grain sediments in the tisza system is obviously less efficient than that of coarse grains, however overestimation is not general if parallel dated samples of the present study are considered. therefore, in the given time range, fine grain ages can still provide valuable data for identifying trends, but on their own they are not suitable for drawing sound conclusions. thus when it is possible some samples has to be subjected to fine grain and coarse grain measurements at the same time to determine the possible degree of overestimation, and this needs to be incorporated to the error term of fine grain results. concerning the morphological evolution of the floodplain levels along the river, results support the late pleistocene – early holocne development of the intermediate floodplain, meaning that the lower floodplain developed in the holocene, in accordance with previous results (hernesz, 2015). incision is suggested to be controlled by tectonics, and therefore it might be possible later to differentiate more stages of the process by the means of further osl results. fig. 6 coarse and fine grain osl ages at site 1 (hódmezővásárhely) and site 2 (deszk) 44 sipos et al. (2016) climate and palaeo-environment on the other hand can have a key role in the dynamics of lateral fluvial development and the rate of point bar formation in case of meanders. nevertheless, further details can be recovered if detailed measurements are initiated on other mega-meanders of the region. acknowledgements the research was supported by the following projects: huro/1101/126/2.2.1, nkfih k-119309 and nkfih k-119193. references adamiec, g., aitken, m. 1998. dose-rate conversion factors: update. ancient tl 16 (2), 37–50. aitken, m. j. 1998. an introduction to optical dating. oxford university press. london. alexanderson, h. 2007. residual osl signals from modern greenlandic river sediments. geochronometria 26, 1–9. doi: 10.2478/v10003-007-0001-6 borsy, z. 1989. az alföld hordalékkúpjának negyedidőszaki fejlődéstörténete (the quaternary development of the great hungarain plain). földrajzi értesítő 38, 211–224. 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10.1016/j.radmeas.2005.11.001 trend analysis of temperature and humidity in kwara state, nigeria journal of environmental geography 13 (3–4), 44–50. doi: 10.2478/jengeo-2020-0011 issn 2060-467x trend analysis of temperature and humidity in kwara state, nigeria adeniyi adedapo¹* department of geography, kwara state polytechnic p.m.b 1375, ilorin, kwara state, nigeria *corresponding author, e-mail: dapomoses@gmail.com research article, received 30 may 2020, accepted 19 november 2020 abstract this paper examines the trend analysis of temperature and relative humidity in kwara state. climatic data on annual mean temperature (minimum and maximum) and relative humidity for 40 years (19782017) were collected from nigerian meteorological agency (nimet) ilorin. semi-average method, mannkendull statistics and regression method were used to analyse the trend in temperature and relative humidity. the standardized anomaly index (sai) was also used to examine the changes in temperature and humidity over the period of 1978 -2017. the result of the analysis indicates that temperature (minimum and maximum) and relative humidity exhibit an upward trend. this implies that temperature and relative humidity increase over the period of 1978 -2017. the mann-kendull statistics values show that there is no significant difference in the values of temperature (minimum and maximum) and relative humidity. the result of the standardized anomaly index (sai) also revealed that the values of temperature and humidity fluctuated around the long –term mean. about 50% of the annual average relative humidity falls above the long term average while 40% of the annual mean maximum temperature falls above the long term average. it can therefore, be deduced that there is the possibility of increment in the values of temperature and relative humidity which could cause a serious challenge to human health and climate change. the study therefore, suggests that increase and fluctuations in temperature and relative humidity should be a critical factor in designing strategies to mitigate the effect of climate change on the environment and human health. keywords: trend analysis, minimum and maximum temperature, relative humidity, fluctuations introduction a trend is a pattern of gradual change in a data gathered sequentially at equal spaced time interval. it is an increase or decrease in the value of a variable occurring over a period of several years. trend is a long-term change (increase or decrease) in a time series (ragatoa, 2018). trend analysis is a technique for extracting an underline pattern of a behavior in a data collected over time, and the science of studying changes in pattern in a time series. trend analysis is generally used to estimate uncertain events in the past and to predict future outcome of an events. trends have become the most frequently used technique to identify climatic variability in r egional and local basis (amadi et. al., 2014). many studies in climate literature have employed trend analysis to examined pattern of changes in climatic parameters, especially variations in temperature. some examined changes in global and regional mean temperature (olofintoye and sule, 2010; jain and kumar, 2012; jones et al., 2013) while some studied trends in temperature on different spatial and temporal scales (ogolo and adeyemi, 2009). according to karaburun et al. (2011) majority of these studies have found an increasing trend in temperature, although the variations differ slightly from one region to another. xu et al. (2017) reported that temperature has increased more than 0.3 °c/decade in most areas in north china and 0.1 – 0.3 °c/decade in most of south china. similarly, ahmad (2015) also reported that variations of temperature over most part of iran from 1961 –2010 show a positive trend with the rate of change varying from 0.09°c to 0.38°c per decade. historical evidences have shown that, since 1880, global mean temperature has increased about 0.85 ± 0.2 ºc (ipcc, 2014). similarly, the general trend of minimum and maximum temperature in nigeria was found to be increasing (ragatao et. al., 2018). temperature and humidity are essential elements in the study of weather and climate forecasting. they are basic environmental factors influencing thermal comfort which is a fundamental concept for climate control systems. variations and fluctuations in climatic elements, especially temperature and humidity, and its consequential effect on the environment and human health has become a global concern. understanding climatic patterns is of great importance when several global challenges such as food insecurity, water crisis, biodiversity loss, and health issues are tied to climate change (ipcc, 2014). changes in surface air temperature are a fundamental indicator of climate change. hansen et al . (2012) examined the trend of global temperature change and reported that the increasing temperature may influence sea level and the extermination of species. similarly, vicente‐serrano et al. (2014) and xie et al. mailto:dapomoses@gmail.com adedapo 2020 / journal of environmental geography 13 (3–4), 44–50. 45 (2011) reported that understanding patterns and trends in relative humidity will reduce uncertainties in the estimation of future climatic changes. therefore, assessment of the characteristics of climatic elements is vital for understanding of both the temporal and spatial variability at local, regional or global scales and their effect on the environment and human health. trend analysis of ambient air temperature and humidity are essential in assessing environmental heat stress on human health (ogbonmwan et al., 2016). field et al. (2012) opined that extremely high air temperatures have a profound effect on huma n and natural systems while wehner et al. (2017) reported that human health and welfare are mainly affected by the combination of high heat and relative humidity. wehner et al. (2017) also noted that the highly cited literature on the impacts of climate change (smith et al., 2014) considers both variations in temperature and humidity on future occupational heat stress. hot and moist air makes people feel uncomfortable, while extremely dry air cause discomfort on human body. high humidity leads to continuous sweating and also cause overheating or heat exhaustion which can lead to dehydration, chemical imbalances in the body and ultimately death. patz et al. (2005) opined that the reproduction and survival rates of bacteria and viruses, which are devoid of thermostatic mechanisms, are greatly affected by temperature variability. according to ye et al. (2013) understanding changes in the surface air temperature and humidity are vital because they can have severe impacts on the hydrological cycle and the surface energy budget. furthermore, lewis and king (2016) also reported that knowledge about the spec ific characteristics of changes in temperature distributions in response to background warming is an essential aspect of fully understanding changes in heat extremes and their related impacts on human and ecosystem health. from the ongoing discussion, it is clear that knowledge about changes in temperature and humidity are critical to human comfort, climate change and other contemporary environmental problems. understanding the uncertainties associated with temperature and humidity patterns will provide a knowledge base for better management of heat stress, climate change and other related environmental hazards. according to meshram et al. (2018) trend analysis of temperature on different spatial scales will help in the construction of future climate scenarios. therefore, the objectives of the study is to examine the pattern of temperature and humidity in kwara state with the aim of creating awareness on the changes in temperature (minimum and maximum) and humidity which are useful information in developing strategies to mitigate the impact of heat stress on human comfort, its impact on climate change and other related environmental problems. study area kwara state is located on longitude 2°6’e and 5°2’e and latitude 7°30’n and 9°40’n. it is situated within the north central geopolitical zone of nigeria. kwara state shares boundary with republic of benin and with five states in nigeria. these states are niger in the north, oyo, osun and ekiti in the south, and kogi in the east. kwara state comprises of sixteen local government areas. in term of population, according to 2006 population census, the population of kwara state was 2,365,353 (npc, 2006). figure 1 shows the map of kwara state showing the topography and the location of weather station. fig.1 map of kwara state showing the topography and location of weather station 46 adedapo 2020 / journal of environmental geography 13 (3–4), 44–50. the climate of kwara state exhibits both wet (rainy) and dry seasons in response to the south west monsoon wind and the north east continental wind which are the major prevailing winds that blow across the state. the wet or rainy season begins towards the end of april and last till october. the dry season begins in november and end in april. the temperature of the state ranges from 33°c to 35°c from november to january and from 34°c to 37°c from february to april. the total annual rainfall ranges from 990.3mm to 1318mm. the rainfall exhibits double maximal pattern. relative humidity ranges from 75% to 88% from may to october and 35% to 80% during the dry season (ajadi and adeniyi, 2017). materials and methods power series polynomial model and trigonometric polynomial or fourier series model are the basic models of trend surface analysis. however, the power series model is used in this study because it is the most frequently used model of trend surface analysis. monthly data on temperature (minimum and maximum) and relative humidity were collected from 1978–2017 from nigerian meteorological agency, (nimet) ilorin. the liquid-in-glass thermometer was used to collect data on minimum and maximum temperature while hygrometer was used to collect data on humidity. these instruments are the most common instruments used for measuring temperature and humidity with high accuracy. these data were collected from the weather station in the ilorin international airport. the 5 year moving average was used to calculate short term fluctuations. semi-average method was used to analyse the trend in temperature (minimum and maximum) and relative humidity. the method was employed because it is more objective than fitting a line by eye to the plotted series. regression method was also used to analyse trend in temperature and humidity. the study period was 40 years 1978–2007 and it was divided into four equal parts to examine the deviation of decadal means from the long term mean. the study period was also sub-divided into two sub periods, 1978–2017 and 1978–2007 based on climatic normal that is 30 years (1978–2007). the essence of the sub-division is to investigate the trend in the climatic elements in relation to the percentage change from 1978–2017. mann-kendall test was used for the analysis of trend (increasing or decreasing) in temperature and humidity. mann kendal test was employed because it is a non parametric test which does not require the data to be normally distributed and also has low sensitivity to short breaks due to inhomogeneous time series (tabari et al. 2011). in addition, it is the most generally used methods and appropriate method of detecting trends. the mann kendall trend test have been extensively used and adapted several times especially in diverse studies on trend analysis (ragata et al. 2018). the method was employed by adeniyi (2016) in the study of spatiotemporal variations of wind flow and its implications for energy generation in the sudanosahelian zone, nigeria and also by birhanu et al. (2017) in the study of temperature and precipitation trend over 30 years in southern tigray, regional state, ethiopia. the standardized anomaly index (sai) was also used to examine the changes in the values of temperature and humidity over the period of 1978-2017. the standardized anomaly index was calculated using the following equation: x . i x sai s d   where: i x = annual total of the parameter x = mean value of the parameter for the period of study s.d = standard deviation from the mean value of the parameter for the period of study. results and discussion fluctuations in annual temperature and relative humidity (1978 – 2017) the graphs in figures 2–4 revealed the fluctuations of minimum temperature, maximum temperature and relative humidity in kwara state (1978–2017). the annual minimum temperature (fig. 2) in the state falls below the long term average in the years from 1978 to 1979, 1981 to 1982, 1984 to 1986, 1990, 1992 to 1998, 2000 to 2001, 2011 and 2015 to 2017. about 43% of the annual minimum temperature falls above the long term average. the longest consecutive years when annual minimum temperature falls below the long term mean were recorded from 1992 to 1998 while the longest consecutive years when minimum temperature falls above the long term mean were recorded from 2003 to 2005 and 2012 to 2014. the annual maximum temperature (fig. 3) in the state falls above the long term average in the years from 1987, 1996, 1998, 2000 to 2003, 2006 to 2011 and 2015 to 2017. fifty percent (50%) of the annual mean maximum temperature falls below the long term average while 40% of the annual mean maximum temperature falls above the long term average. the longest consecutive years when annual mean maximum temperature falls below the long term mean was recorded from 1979 to 1984 while the longest consecutive years when minimum temperature falls above the long term mean was recorded from 2006 to 2011. figure 4 revealed that the annual relative humidity in the state falls below the long term average in the years from 1982 to 1985, 1987 to 1990, 1992 to 1998, 2000 to 2002 and 2008. about 50% of the annual mean relative humidity falls above the long term average. the longest consecutive years when annual relative humidity falls below the long term mean was recorded from 1992 to 1998 while the longest consecutive years when minimum temperature falls above the long term mean was recorded from 2009 to 2005 and 2017. the above findings show that temperature (minimum and maximum) and relative humidity varies from year to year and fluctuated around the long term mean. adedapo 2020 / journal of environmental geography 13 (3–4), 44–50. 47 fig.2 annual minimum temperature fluctuations for kwara state fig.3 annual maximum temperature fluctuations for kwara state fig.4 annual relative humidityfluctuations for kwara state deviation of decadal means of climatic parameters in kwara state (1978–2017) table 1 shows the deviation of the decadal mean values of minimum temperature, maximum temperature and relative humidity from the long term 1978–2017. the highest deviation of decadal mean of minimum temperature was in 2008 to 2017 (+0.2) while that of maximum temperature was in 1998 to 2007. the lowest deviation of decadal mean of relative humidity (+0.6) table 1 deviation of decadal means of climatic parameters in kwara state (1978-2017) period deviation of decadal mean minimum temperature maximum temperature relative humidity 1978 – 1987 0.00 -0.2 +0.6 1988 – 1997 -0.1 -0.3 -4.1 1998 – 2007 +0.1 +0.3 +0.7 2008 – 2017 +0.2 +0.2 +2.7 table 2 deviation of the 1978 – 2017 means of climatic parameters from 1978-2007 in kwara state climatic elements 1978 2017 1978 2007 change change [%] minimum temperature [0c] 21.7 21.6 -0.1 -0.46 maximum temperature [0c] 32.5 32.4 -0.1 -0.31 relative humidity [%] 74.0 73.0 -1.0 -1.35 was in 1978 to 1987. temperature (minimum and maximum) and relative humidity exhibit positive deviation of decadal mean in 1998–2007 and 2008– 2017. this implies that there is an increase in the values of temperature and relative humidity from 1998–2017. the negative signs show a decrease in the values of the climatic parameters. deviation of the 1978–2017 means of climatic parameters from 1978–2007 the period under study, 1978 to 2017 was divided into two subperiods, 1978–2017 and 1978–2007 to show the deviation of the means of temperature (minimum and maximum) and humidity of 1978–2017 from 1978–2007. table 2 shows a decrease in percentage change of minimum temperature, maximum temperature and relative humidity. there was a decrease of –0.46% of minimum temperature and -0.31% decrease of maximum temperature. relative humidity has -1.35% decrease in percentage change. the negative change in the percentage of change implies that there were declines in the values of minimum temperature, maximum temperature and relative humidity in the state from 1978 -2007, though the rates of deviation were small. variation of temperature and relative humidity (1978– 2017) figures 5–7 show the variation of the mean and the 5 year moving average of minimum temperature, maximum temperature and relative humidity in kwara state from 1978 to 2017. the annual values of minimum temperature fluctuated from 21.0°c in 1989 to 22.6°c in 1987 (fig. 5). figure 6 shows that maximum 48 adedapo 2020 / journal of environmental geography 13 (3–4), 44–50. temperature fluctuated from 31.4°c in 1997 to 33.5°c in 1998 while that of relative humidity fluctuated from 71% in 1985 to 79% in 2009 (fig. 7). this implies that there were little variations in the values of temperature (minimum and maximum) and relative humidity. similarly, the smoothed by running averages for the period of 5 years also revealed that there is little variation in the values of temperature and relative humidity. fig. 5 trend of 5-year moving average of annual minimum temperature in kwara state fig. 6 trend of 5-year moving average of annual maximum temperature in kwara state fig. 7 trend of 5-year moving average of annual relative humidity in kwara state trend in temperature and relative humidity using semi average method the annual value of minimum temperature, maximum temperature and relative humidity for the period of 40 years, (1978 to 2017) were analyzed for trends using semi average method (table 3). from the table, minimum temperature, maximum temperature and relative humidity exhibit an upward trend, although the changes are very small. this implies that values of temperature (minimum and maximum) and relative humidity in the state will keep on increasing. in addition, it also indicates a warming trend. this finding of increase in temperature agreed with the report of the international panel on climate change (ipcc) (2013) which state clearly that temperature trends on a global scale show a warming of 0.85 (0.65-1.06)°c, over the period 1880–2012. trend in temperature and relative humidity using mann-kendull statistics (1978-2017) the result of the trend analysis using mann-kendull statistics shows increasing (positive) trends in the values of temperature and humidity. the result of the statistics in table 4 also shows that there is no significant difference in the values of temperature (minimum and maximum) and relative humidity at either 95% or 99% probability levels. this is because the values of the mann-kendull statistics (r) is less that the theoretical value (r)t. this implies that no differential pattern of variation exist in the values of temperature and relative humidity in the state. table 3 trend in temperature (minimum and maximum) and relative humidity using semi average method climatic elements first part avg. second part avg. trend minimum temperature [°c] 21.6 21.8 upward trend maximum temperature [°c] 32.2 32.7 upward trend relative humidity [%] 71.9 75.3 upward trend table 4 trend in temperature (minimum and maximum) and relative humidity using mann-kendull statistics climatic elements r minimum temperature 0.06 maximum temperature 0.23 relative humidity 0.17 adedapo 2020 / journal of environmental geography 13 (3–4), 44–50. 49 trend analysis of temperature and humidity using linear regression method figures 8–10 show the actual, trend lines and trend equations of temperature (minimum and maximum) and humidity in kwara state (1978–2017). from the figures (figures 8–10), the trend lines show an upward trend. this implies that there is an increase in the values of temperature (minimum and maximum) and relative humidity. in addition, no definite break in the trend of temperature and humidity is observed, although the values fluctuate. the rate of increase in trend is very small. however, an increase in temperature leads to climate change which can negatively affect weather and consequently cause many climatological hazards like drought. fig. 8 trend of annual minimum temperature in kwara state fig. 9 trend of annual maximum temperature in kwara state fig. 10 trend of annual relative humidity in kwara state conclusions and recommendations the trend analysis of temperature and relative humidity for 40 years (1978–2017) in kwara state revealed that annual mean values of minimum temperature, maximum temperature and relative humidity fluctuated around the longterm mean. fifty percent (50%) of the annual mean maximum temperature falls below the long term average while 40% of the annual mean maximum temperature falls above the long term average. about 50% of the annual mean relative humidity falls above the long term average. this means that the identified climatic parameters in the years under review have show both below and above long term mean pattern. the deviation of decadal means of temperature and relative humidity from the long term mean shows positives in 1998–2007 and 2008–2017. the result of trend analysis shows that temperature and relative humidity exhibits an increasing trend. the increase in temperature indicates a warming trend. this implies that the state is vulnerable to the effect of global warming which is dangerous to the environment and human health. the result also suggests that the increase in temperature can lead to an increase in heat index which can lead to heat disorders such as pain, blisters, fever, headaches, heavy sweating and heat stroke or sunstroke. in addition, increase in temperature can lead to climatological hazards like drought and climate change. the increase in temperature and relative humidity could be as a result of impact of urbanization and other anthropogenic activities in the state. therefore, the study recommends that potential increase in temperature and relative humidity should be a critical factor in designing strategies to cope with and reduce the effect of climate change on the environment and human health. references adeniyi, a. 2016. spatio-temporal variations of wind flow and its implications for energy generation in the sudano-sahelian zone, nigeria. ph.d. 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2017. climate variability and trends at a national scale. scientific reports 7, 3258. doi: 10.1038/s41598-017-03297-5 https://epic.awi.de/id/eprint/37530/1/ipcc_ar5_syr_final.pdf https://www.jstor.org/stable/24080385 https://cdiac.ess-dive.lbl.gov/trends/temp/jonescru/jones.html http://www.idosi.org/wasj%20/wasj12(10)/2.pdf http://www.idosi.org/wasj%20/wasj12(10)/2.pdf introduction study area materials and methods results and discussion fluctuations in annual temperature and relative humidity (1978 – 2017) deviation of decadal means of climatic parameters in kwara state (1978–2017) deviation of the 1978–2017 means of climatic parameters from 1978–2007 variation of temperature and relative humidity (1978–2017) trend in temperature and relative humidity using semi average method trend in temperature and relative humidity using mann-kendull statistics (1978-2017) trend analysis of temperature and humidity using linear regression method conclusions and recommendations references journal of environmental geography journal of environmental geography 9 (1–2), 7–13. doi: 10.1515/jengeo-2016-0002 issn: 2060-467x analysis of urban sprawl dynamics using geospatial technology in ranchi city, jharkhand, india firoz ahmad1, laxmi goparaju2* 1department of remote sensing, birla institute of technology, ranchi ormanjhi road, mesra, ranchi 835215, jharkhand, india 2vindhyan ecology and natural history foundation, 36/30 station road, dhauru pur, mirzapur 231001, uttar pradesh, india *corresponding author, e-mail: goparajulaxmi@yahoo.com research article, received 1 march 2016, accepted 11 may 2016 abstract the availability of remote sensing satellite data at various spatial, temporal and spectral resolutions provides enormous opportunity to map the urban sprawl. when coupled with geographic information system (gis) it is possible to evaluate, analyse and integrate large data. we need to understand and quantify the urban sprawl on spatial and temporal scales which forms a basis for better planning and sustainable management of cities and towns. the city of ranchi has witnessed unprecedented urban growth after assuming the status of a capital of jharkhand state, india in 2000. the increasing population has put pressure on the natural resources of the city. the urban growth has been in a haphazard manner at the cost of agricultural lands, forest land and open green spaces such as park, garden and recreational forestry. the present study analysed the urban sprawl in ranchi city, using landsat data from 1976, 2002 and 2015. the study revealed that the annual urban growth rate was 1.76 ha/yr over the period from 1976 to 2002 whereas the annual growth rate was 2 ha/yr over the period from 2002 to 2015. the northern side of the city has witnessed more expansion in 2002 when compared with the growth in 1976. increase in urban density was seen at the distances of 3, 4,5,6,7 and 8km between 1976 and 2015 and the rate was higher than 25%.the driving factors of the development were infrastructure, educational and business expansion. thus, spatial analyses of urban sprawl are a prerequisite for curbing the unplanned urban growth and ensure sustainable living. keywords: urban sprawl, geospatial, landsat, ranchi, urbanization introduction the ever increasing population has led to the rise in unplanned urban growth in the suburbs of the city which is usually termed as urban sprawl (theobald, 2001; bugliarello, 2003). urban growth on one hand is an indicator of economic, social and political growth whereas, on the other hand it is at the cost of forests, agriculture lands, orchards and greenery of the city (torrens and alberti, 2000; barnes et al., 2001). there are several definitions which define urban sprawl; bhatt et al. (2010) had described it as an unplanned and uneven pattern of growth driven by various processes finally leading to inefficient resource utilization. there are several negative impacts associated with urban sprawl, some of them are having an impact on ecosystem and forests leading to fragmentation of habitats (macie and moll, 1989) increase in air/water pollution and greenhouse gases due to increase in fossil fuel consumption (stoel, 1999) and increase in traffic congestion (silambarasan, 2014). accelerated urbanization is the current scenario in india, one of the most populated nations of the world. the urban population in 1901 was 26 million, which rose to 62 million in 1951. the period between 198 and 1991 witnessed a rise to a figure of 285 million, accounting 27.8% of the total population (jaysawal and saha, 2014). the degree of urbanization varies in different states of india, with goa being the most urbanized state constituting 49.77% of the urban population. other states like gujarat, karnataka, rajasthan, madhya pradesh, bihar and jharkhand are reported to have medium urbanization (census, 2001). it is necessary that urban sprawl is quantified and studied at local and regional scales such that proper measures are taken to ensure sustainability in urban planning. the parameter which can be used to quantify it is the built up area (epstein, 2002). the conventional methods of mapping are time consuming and require heavy manpower, thus becoming a herculean task. an advanced technological approach which is able to provide us accurate information over different time scales is required. in light of this, satellite remote sensing data in conjunction with geographic information systems (gis), provides an opportunity to study urban sprawl (pande et al., 2012; longeley, 1999). in the past four decades in india, satellite remote sensing data have been used extensively to monitor earth’s natural resources and study the changes taking place on the surface over different time periods. several studies have analysed urban sprawl at regional, local and temporal scales (boori et al., 2015; griffiths et al., 2010). the urbanization pattern of the greater asmara area in eritrea was studied using satellite remote 8 ahmad and goparaju (2016) sensing data of landsat. they analysed land use/ land cover change using a data object based image analysis and urban sprawl using shannon entropy (tewolde and cabral, 2011). urban sprawl of the ajmer city (rajasthan was studied at mid-scale level for 25 years (1977-2002) where they used landsat tm,mss,etm+, and irs liss iii data (jat et al., 2008). landsat imagery of kansas city of united states of america (usa) was used to generate a time series of land cover data over the past three decades (wei et al., 2006). long term trends and patterns of urban sprawl were studied. in south india and its surrounding area, by rahman et al. (2010) using irs p6 data and topographic sheets in the gis domain along with shannon’s entropy model to assess the urban sprawl. in the udupi district of karnataka state in india, urban sprawl patterns were analysed using (liss and pan images of 2003 and liss iv and cartosat images of 2013), which showed that barren /waste land was also converted to settlement /built up area (silambarasan, 2014). singh et al. 2014 have studied the urban expansion in ranchi city during the period from 1996 -2007 using an irs liss iii sensor. similarly, pandey et al. (2012) using cartosat –i stereo pairs satellite images studied the urban built up area of ranchi township for over a period of eight decades (1927-2010). the present study is an attempt to quantify urban sprawl in the ranchi city for a period of 39 years using landsat data of 1976, 2002 and 2015. the city which is the 46 th largest urban cities in india and the third largest in the state after jamshedpur and dhanbad (census, 2011). it is known for coal belts and forests (jha, 2016). the population is mainly dominated by tribes whose primary source of income is derived from agriculture, cattle farming and collection of forest produce. deforestation, which is a consequence of urbanization has left these forest dependent communities in a pitiable situation. low agriculture produce and poor economic condition of farmers has led them to migrate to better places in the vicinity of major towns. establishment of industries, infrastructure development, education and health facility etc. have attracted rural population to capital city (kumar et al., 2011). the objectives of the present study are 1) evaluating the urban growth in ranchi city for the years 1976, 2002 and 2015 using landsat data and gis. 2) analysing and quantifying the urban sprawl of ranchi city during the three time periods mentioned above. it is believed that the urban growth or expansion has taken place more rapidly after the creation of the capital city of ranchi. thus, the study aims to analyse the urban growth patterns before and after the formation of the capital city. study area the study area is the city of ranchi. it is the capital of jharkhand state of india, which was, carved out of the bihar state on 15th november 2000. the southernmost part of the earlier state of bihar constitutes jharkhand. since then it has progressed as a capital city opening opportunities for new employment, trade and infrastructure development. the city is located between 850 13’ to 850 25’e and 230 13’ to 230 26’ n. the latitude and longitude of city center are 23°22′n; 85°20′e. the average elevation fig. 1 the location of the study area a) map of india b) map of jharkhand and c) relief map of the study area https://tools.wmflabs.org/geohack/geohack.php?pagename=ranchi&params=23.36_n_85.33_e_ analysis of urban sprawl dynamics using geospatial technology in ranchi city, jharkhand, india 9 of ranchi city is 652 m from sea level. its municipal area is 175.12 km2. the city is adorned with numerous waterfalls and is also known as “city of waterfalls”. the local river system constitutes subarnarekha and its tributaries. the city’s water supply is fulfilled by kanke, rukka and hatia dams (pandey et al., 2012). the pleasant climate of ranchi prevalent throughout the year is because of its location and the surrounding forests. it was once the summer capital and was given the status of the hill station. summer temperatures range from 20 °c to 42 0 c, winter temperatures from 0 °c to 25 0 c degrees. the coolest months are december and january. the annual rainfall is about 1430 mm (56.34 inches). figure 1 shows the location of the study area. the census in india is conducted at an interval of ten years. the population of ranchi city as per census data for the past four decades is as follows: in 1971, 255 thousands of human population; in 1981, 489 thousands; in 1991, 599 thousands; in 2001, 846 thousands and in 2011, 1073 thousands (ranchi master plan 2037, 2015). material and methods image acquisition and preprocessing the satellite image used for the analysis was of landsat 2 mss (1976); landsat 7 etm + (2002) and landsat 8 (tirs) for the year 2015. the details of the data are given in table 1.the satellite data selected was cloud free. all the datasets were downloaded from united states geological survey (usgs) website as a georeferenced data set. the images were corrected for radiometric and atmospheric distortions during the preprocessing stage. the data obtained was in a geo tiff format for each individual band. the various bands were layer stacked to produce a composite image which was converted into img format for further study and analysis. image processing software used was erdas imaging (version 9.0) and arc gis spatial analyst (version 10.1). table 1 details of satellite data image dates 20-12-1976 23-12-2002 9-5-2015 spacecraft landsat 2 landsat 7 landsat 8 sensor mss etm+ oli_tirs spatial resolution (m) 60 30 15 (pan) 30 15 (pan) radiometric resolution (bit) 8 8 16 number of bands 4 8 11 path / row 151/44 140/44 140/44 projection utm utm utm zone 45 45 45 datum wgs84 wgs84 wgs84 ellipsoid wgs84 wgs84 wgs84 image classification the bands utilized for analysis are landsat mss (4, 3, 2); landsat 7 etm+ (5, 4, 3) and landsat 8 (5, 4, 3). the study area was extracted from the false colour composite (fig. 2). the images retained their original pixel size despite the chances that there might be a difference in classification accuracies. to maximize correspondence between classified maps, a uniform methodology was applied on each dataset. the urban area boundary was visually interpreted on false colour composite and extracted from each of the datasets of three time periods. on fcc it appears as cyan/white and of various geometric shapes such as rectangle, square, etc. in each of the extracted urban area data, normalized difference vegetation index (ndvi) was executed to delineate the vegetation classes in the urban landscape by using the density slicing method (singh, 1989; pilon et al., 1988). the ndvi is the best suited index to delineate vegetation from the fcc. an unsupervised classification approach is a classification procedure based on isodata algorithm, in which the similar pixels are assigned into a group (lillisand and keifer, 2004). thus, it was used for extracting water and urban (settlement). finally vegetation, urban and water were integrated in one layer using the erdas imagine model maker. flowchart (fig. 3) shows the methodology adopted for the following study. thus, according to anderson (1976) we successfully delineated first level of lulc classes, namely vegetation, water and urban for each time period. the description of various classes is mentioned in the given table 2. accuracy assessment is a significant step in image classification for evaluating quality of classified image (forkuoand and frimpong, 2012). accuracy assessment was computed for each classified dataset using a stratified random sampling method wherein 100 points were generated for each category and each point was assigned to the respective class based on ground knowledge. fig. 2 the study area –false colour composite (fcc) of landsat data (2015). the bands used are nir-band 5, r-band 4, and green-band 3 along with multi buffer ring around the city 10 ahmad and goparaju (2016) fig. 3 flow chart explaining the methodology table 2 description of land use/land cover classes urban/built up residential, commercial, industrial , transportation, roads, mixed urban and open in urban vegetation agriculture, plantation, parks, orchards and forest water bodies dams or reservoirs, ponds, river, lakes, stream, seasonal waterlog area after classification of the images, multi buffer rings were created in arc gis (using the multiple ring buffer option), specifying the distance of 1 km from the city centre. ten such rings were generated each ring of 1 km buffer. beyond the tenth ring, one ring of 5 km buffer was generated. in erdas imagine the matrix option of gis utility was utilized to extract the area of each class in different ring. the city center point of our study is taken firayalal chowk (latitude and longitude 23°22′12" n; 85°19′30" e). the matrix generated for all the time periods were analysed in ms excel for urban density and urban growth rate using the following formulae (1) respectively: 𝑈𝐷 = 𝑆𝐴 𝑇𝐴 (1) where ud means urban density of the specified ring, sa implies settlement area of the specified ring and ta means total area of the specified ring. urban growth rate in order to monitor the spatial distribution of urban expansion intensity, we adapted the annual urban growth rate index (agr). annual urban growth rate (agr) is used for evaluating the speed of urbanization (maquboli et al., 2015; boori et al., 2015). agr (2) is defined as follows (xiao et al. 2006): 𝐴𝐺𝑅 = 𝑈𝐴𝑛+𝑖−𝑈𝐴𝑖 𝑛𝑇𝐴𝑛+𝑖 × 100 % (2) where agr means annual growth rate, an+i refers to the total land area of a ring, and nt is the interval of time (no. of years) between initial and final year; uan+i denotes the urban area at the final year whereas uai denotes the urban area at the initial year. results and discusion land use/land cover maps the final output map of land use/land cover shows three major categories that are vegetation, settlement (urban/built-up) and water (fig. 4). the overall accuracy of the land use/ land cover of the year 1976, 2002 and 2015 were 90%, 92% and 92% respectively. the kappa accuracy, noted was 0.83, 0.87 and 0.87 respectively. the complete area statistics of land use/land cover of the year 1976, 2002 and 2015 is given in table 3. for all the three time periods analysed, it is seen in table 3 that there is an increasing trend in the urban area from 1976 (5034.16 ha), 2002 (10,335.24 ha) and in 2015 (14,561.39 ha) whereas the area of vegetation first decreased from 10.69% in 1976 to 9.23% in 2002 and later slightly increased to 9.71% in 2015. the area of water has first increased from 0.53% to 1.38 % from 1976 to 2002 and later on reduced to 0.81% in 2015 (table 3). the increase in water is attributed to the fact that in 1976, the kanke dam site was not included in urban built up area, in 2002; the kanke dam reservoir has been included. whereas in 2015 the decrease in water body is because of seasonal variation as the data belongs to the summer season. later using the equation 2 and details from table 3, urban growth was calculated. it was seen that 58.53% growth in built up area (settlement) over the period of 39 years from 1976 to 2015. in the first 26 years (from 19762002), urban growth was 45.84% at an average annual growth rate of 1.76 ha/yr. in between time period (2002 – 2015) over the period of 13 years urban growth was analysis of urban sprawl dynamics using geospatial technology in ranchi city, jharkhand, india 11 25.96% with the average annual growth rate 2 ha/yr. thus, the city expanse rate has increased furthermore 13.6% (0.24 ha/year.) over the period of 2002 to 2015 when compared with the period 1976 to 2002 (fig. 5). fig.5 urban growth of ranchi city urban density patterns and urban growth rate the city (land use/land cover class) density patterns around the city center were also examined to ascertain whether different zones have represented different densities. figure 6 shows 11 (10+1) buffer ring zones from 1 to 10 km at a distance of 1km each and one 5 km buffer ring from 10 to 15 km distance. the observations show that it has been reasonably true that the first three zones represent the areas that are within the walking distance from the city center. it is observed that in the city center, the urban density was more than 85% for the last 39 years. in 1976, urban density was reduced dramatically around 50.8% on the distance of 3 km from the city center and 15.6% on 5 km, and less than 1 % at 15 km (11th ring). when comparing the time periods of 1976 and 2015 on the distances of 3, 4, 5, 6, 7 and 8 km, the urban density has increased very high (more than 25%).if we compare only the time periods of 1976 and 2002 at the distances at 3, 4 and5 km, the urban density has highly increased (more than 25%). from 2002 to 2015, at the distances of 7 and 8 km, urban density was increased (more than 15%) (fig. 6). in 1976, at the city center urban density was 86%, the share of vegetation was 8.6%, and water was 5.3% (fig. 6). from 1 to 2 km distance from the center, the urban/built-up area reduces to (76.13%) and fig.4 multi buffer ring around the city overlaid on land use/land cover map in 1976, 2002 and 2015 table 3 zonal statistics of land use/land cover (1976, 2002 and 2015) land use/ land cover area in 1976 (ha) % area in 2002 (ha) % area in 2015 (ha) % urban (settlement) 5034.16 88.77 10335.24 89.38 14561.39 89.46 vegetation 606.24 10.69 1067.49 9.23 1581.74 9.71 water 30.61 0.53 160.11 1.38 133.01 0.81 total 5671.01 100 11562.84 100 16276.14 100 12 ahmad and goparaju (2016) vegetation increases to 12.3%. from 2 to 3 km distance from the center, the urban/built-up area reduces to (50.8%) and vegetation also reduced to 5.82%. from 4 to 6 km distance, both urban and vegetation classes were showing a decreasing trend. in 2002, the city center urban density was 91%, the share of vegetation was 5.3%, and water was 3.7% (fig. 6). at a distance of 1-2 km from the center, the urban/built up area is more or less the same (90%) whereas vegetation has increased up to 7.7%. at a distance of 2 to 3 km from the center, the urban/built-up area very slightly reduces to (87.3%) and vegetation has reduced to 5.35 %. at a distance of 4 to 5 km from the center, the urban/built-up area sharply reduces to 50.78% and vegetation has also shown a decrease of 3.6 %. from 5 to 6 km distance from the center, the urban/built-up area sharply reduces to 25.74% and vegetation has reduced to 1.58 %. at 15 km (11th ring) the urban/built-up area was 2% and vegetation has decreased to less than1 %. in 2015 (fig. 6) at the city center, urban density was noted was 92.6% and vegetation was 2%, and water was 5.3%. from 1 to 3 km distance, urban/built-up areas reduce at a slow pace to 88.2 %, but the vegetation area increased to 9.1 %. from 6 to 7 km distance from the center, the urban/built-up area increased to 42 % and vegetation has increased to 4.85 %. from 7 to 8 km distance from the center, the urban/built-up area reduces to 35.37% and vegetation has reduced to 4.54 %. from 1 to 8 km distance from the center, the urban/built-up area has always been found to be greater than 35 % in 2015 whereas urban/built-up area was always found to be greater than 35%, in 2002 is up to 1 to 5km distance. urban/built-up density and vegetation is continuously showing decreasing trend from 7 km onwards to 15th km(11th ring) reached up to 5.3 %, 0.27% respectively at 11th ring. description of spatial expansion it is observed that in 2002 the northern side of the city has more urban growth as compared to the growth in 1976 as seen in figure 4. the city has witnessed growth and development in north east, north west, west and south from the core of the city. it has been noticed that major growth is concentrated along national highways (nh-23, nh-33 and nh-75) which serve as major transportation corridors. even though it is observed that built up development took place in ranchi in a haphazard manner (kumar et al., 2011). since past 83 years as records say the township has increased more than six times (pandey et al., 2012). earlier the built up area was concentrated around the city center like ranchi lake and northern parts like kanke, later, after 1976, a sudden increase built up area in north, east and west of the city centre was seen. a whole sale vegetable market pandra mandi is situated at a distance of 8 km from the city centre (along nh-75), which is a hub for villagers to sell their produce. it is equipped with modern facilities to store the farm produce. various institutes like indian institute of coal management (established in 1994) in kanke, reliance mega mart, birsa agricultural university (faculty of forestry established in 1980) are some of the major institutes and shopping complex in this area. in the north of the city, along kanke dam are new establishments in localities like morabadi, jawahar nagar and gandhinagar. new colonies such as pundag, nijam nagar and bhitha basti have sprouted which once bore a deserted look few years ago. national highway (nh-23) in northeast leads to mesra which has become an educational hub with various new technical and educational institutions. in the south of the city after ranchi became a capital, massive expansion of ranchi airport is seen. it is an extension of doranda locality and with the development people have started residing there too. in the west is the harmu nadi, where once open fields were there, now taken over by residential and commercial establishments. engineering and medical colleges have come up in areas like baryatu, tatisilwai and namkum, which are on the outer fringes of the ranchi city. in 2007, khelgaon a sports complex has also been established at hotwar (along nh-23) during the national games. future growth is likely to be noticed in and around areas like kanke, bariayatu, ratu, buti, namkum, tatisilwai and hatia. thus, the increase in built up area has been at the cost of agriculture and open fields. higher development is observed in low elevation zones due to availability of ground water (pandey et al., 2012). as over a period of time, demand for water has increased, putting at stake the water bodies in the ranchi urban area. fig.6 land use/land cover class density percentage from 1-15 km distance for 1976, 2002 and 2015 analysis of urban sprawl dynamics using geospatial technology in ranchi city, jharkhand, india 13 conclusions the above study shows that coarse resolution satellite data like landsat can be successfully used to monitor the urban sprawl of ranchi city. the study quantifies the urban sprawl at various distances from the city centre. simultaneously, changes in vegetation and water were also noted. initially the urban/built up area was concentrated in the city centre, which gradually spread both north and south directions. mostly land used for urbanization was open spaces in the city and left over lands between adjoining buildings. later, vegetated areas were also converted to built up area. as a result, the city has witnessed increase in traffic congestion, pollution, and loss of the green cover, erratic rainfall and unpleasant weather. in order to achieve sustainability in urban planning, we should develop the open spaces as parks, playgrounds and nurseries. along roadsides spaces should be spared for planting trees which provide shade and purify the polluted air. water bodies should not be encroached for residential purposes. a buffer around them must be left before any construction work is undertaken. water conservation practices should be encouraged by the government as well as the public to combat the water crisis in the future. such data are vital information for city planners and managers to curb unplanned urban growth provide proper drainage facility and ensure that the natural resources are not exploited badly. incorporating such data in town planning and management would benefit the citizens and further ensure a sustainable livelihood. acknowledgements the authors are grateful to usgs portal for the free download of landsat data 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(2000). measuring sprawl. working paper no. 27, centre for advanced spatial analysis, university college, london. wei,j., jia,m., twibell, r.w., underhill.k. 2006. characterizing urban sprawl using multistage remote sensing images and landscape metrics. computers environment and urban systems 30 (6), 861–879. doi: 10.1016/j.compenvurbsys.2005.09.002 xiao, j., shen, y., ge, j., tateishi, r., tand, c., liang, y., huang, z. 2006. evaluation urban expansion and land use change in shijiazhuang, china, by using gis and remote sensing. landscape and urban planning 75, 69–80. doi: 10.1016/j.landurbplan.2004.12.005 journal of environmental geography journal of environmental geography 9 (1–2), 15–21. doi: 10.1515/jengeo-2016-0003 issn: 2060-467x open source web gis solutions in disaster management – with special emphasis on inland excess water modeling levente juhász1, ádám podolcsák2*, jános doleschall2 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 2compet-terra kft., kálvin tér 2, h-6721 szeged, hungary *corresponding author, e-mail: adam.podolcsak@competterra.com research article, received 24 february 2016, accepted 26 may 2016 abstract in recent years, the increased frequency of inland excess water in the carpathian basin gets more and more attention. the authors developed a web based pilot application for disaster management, with special emphasis on inland excess water hazard management. free and open source software was used to generate a model, and our work was based on web gis standards (ogc), which makes further development possible. the developed web gis application provides functions to support the data collection regarding channels and ditches, and on-line hydrological analysis based on ogc web processing services (wps). hydrological analysis aims to visualize the areas potentially at risk, depending on different precipitation quantities and various values of influencing factors. in order to run the prototype a sample data set was gathered including reference maps, technical parameters and current condition of canals and ditches. the methodology of crowdsourcing can produce valuable volunteered geographic information (vgi) that can fulfill the data requirements of disaster management applications. the prototype supports crowdsourcing in the following aspects: free user access to the system’s analysis functionality, stakeholders may digitize the position of ditches, modify the status of the existing ditch system according to current conditions and add or modify parameters relevant for the analysis. the application demonstrated the usability of stakeholder generated geographic information and web processing for disaster management. the idea of integrating user-generated data into the various tasks of a disaster management agency is promising. however, maintaining data quality and standards compliance remain important issues. keywords: crowdsourcing, volunteered geographic information, open source, web processing, disaster management introduction the united nations office for disaster risk reduction defines disaster management as the organization and management of resources and responsibilities for addressing all aspects of emergencies such as preparedness, response and initial recovery steps. disaster management involves plans and institutional arrangements to engage and guide the efforts of governmental, non-governmental, voluntary and private agencies in comprehensive and coordinated ways to respond to the entire spectrum of emergency needs (unisdr). a common view is that disaster management is a continuous cycle of pre-disaster, response and post-disaster phases (fig. 1). the role of gis remained more research-oriented than operational until the beginning of the 21th century (zerger and smith, 2003). in recent years, most of the technological barriers have been overcome and numerous operational applications and adaptations of gis exist all over the world. examples show the wide usage of mobile gis as an effective, fast and cheap data collection method (montoya, 2003; chen et al., 2010). however, applications are not limited to data collection. several examples can be found in literature that use complex modelling methods for disaster management (alparslan et al., 2008). a prominent example was designed to mitigate the harms of earthquakes in bolu provance, turkey by applying a complex suitability model. the lack of dynamics in early examples is obvious. currently, web gis and the development of web based gis applications are much more widespread. standards provided by ogc (open geospatial consortium) and readily available compliant software components make application development easier and faster. another important aspect of such application is the data being used. it is hard to disagree that decisions made during a disaster can both affect properties and lives, so data quality is an important factor. on the other hand, insufficient amounts of data can limit the success of every task in disaster management, so using alternative data sources should also be considered. crowdsourcing is a method that uses voluntary contributors to do a specific task (estellés-arolas and gonzález-ladrón-de-guevara, 2012). for disaster management, it is possible collect data from volunteer individuals. the spread of crowdsourcing is strongly related to the growth of the digital world. a great amount of people use the internet and many of them have smartphones as well. in 2012 68% of the hungarian households had broadband internet connections (ksh, 2014). in the first quarter of 2013, data traffic was 20% larger than in the same period of 2012. this fact represents mailto:adam.podolcsak@competterra.com 16 juhász et al. (2016) the growing usage of smartphones in hungary (ksh, 2014). these platforms can be the basis of a successful crowdsourcing application. however, organizing and processing crowdsourced data can be challenging. the main task is to ensure that the data produced by the “crowd” adheres to predefined standards. this kind of data is often referred as volunteered geographic information (vgi) in literature (goodchild, 2007). all research agrees that it is highly heterogeneous and can be massive in volume. another aspect is the lack of traditional quality assurance (qa) techniques in most vgi platforms (goodchild and li, 2012). terminology used in scholarly literature is not standardized yet but a number of researchers suggested different classifications of vgi (craglia et al., 2012). geographic information is essential for emergency managers in all phases of emergency management. data quality is a major factor since ineffective decisions caused by incorrect or imprecise data can both affect lives and properties. the possible benefits of using vgi during crises can make it a significant source of information by providing relevant data almost real-time (goodchild and glennon, 2010; li and goodchild, 2010). previous studies have shown the importance of vgi during a crisis event. geo-social media is ideal for emergency communications. moreover, it can be considered as an information source for emergency managers (vieweg et al., 2010; lantonero and shklovksi, 2010) since there are more than six billion human potential “sensors” in the world. those citizen sensors can collect and share relevant crisisrelated information through various platforms (goodchild, 2007). it is important to show that a significant portion of users who share relevant information also include some kind of location information in their messages (vieweg et al., 2010; maceachren et al., 2011). this information therefore can be easily placed in the geographic space. recently, a new cooperation has been started in hungary. the directorate for disaster management and the university of szeged teamed up to survey all the fire hydrants within csongrád county. the directorate asked university students to collect information of each fire hydrant, survey its position and take a picture of the surroundings. officials of the directorate trained students what information is needed and how to collect them. the university provided the gis equipment and the methodology. since then, the data collected during the survey (including photos and databases) is being used by the fire department of the directorate to make their operative work more effective. operators in the center guide field teams to the appropriate fire hydrant and provide them relevant information while in the field (huszár et al., 2013). properties of the rain and residual water drainage systems (spatial extent, condition, width, depth) and other anthropogenic establishments are relevant data for modelling inland excess water (rakonczai et al., 2011; szatmári and van leeuwen, 2013; leeuwen et al., 2013). as vivacqua and borges (2011) mentioned, knowledge of past events plays an important role in emergency situations. in the case of inland excess water, this knowledge can be gathered from local individuals. in addition, free and open source software are now common in gis and geography as well. all kinds of gis software can be found depending on the needs, although their categorization is not easy (steiniger and hunter, 2013). steiniger and weibel (2009) have identified seven major types of them: • desktop gis • spatial database management systems • web map servers • server gis • web gis clients • mobile gis • libraries and extensions earlier, most open source and free software were developed by research institutes, universities or government agencies. in recent years, most of these projects are being developed by a new industry that develops and supports open source software. private companies have also joined the market. in opinion of siki (2009), the main benefits of using free and open source software are not the low price but the direct interaction between the developers and users. they fig. 1 disaster management cycle (barnier 2006) open source web gis solutions in disaster management … 17 all belong to the same community resulting in shorter development periods. using open source and free software is also financially beneficial since instead of spending money on commercial licenses, resources can be reallocated to actual development tasks. a web-based application named vingis can be mentioned in hungarian literature that uses postgresql, php and mapserver as open source components (katona and molnár, 2005). international examples cover the wide range of disaster and emergency management such as ushahidi (non-profit software company that develops free and open source software (lgpl) for information collection, visualization, and interactive mapping), that support resource organization and management. considering the above, the main goal is to develop a web platform, which supports the crowdsourcing based local management of environmental hazards. with the platform the defenses against surface water hazards at local level can be made easier and more effective; hazards (excess or lack of surface water) may cause less damage to the local economy. the further aim for developing the web platform is to use only free and open source technologies. this would be able to reduce the financial cost of development of disaster management application drastically while making them easier to distribute and increase the user base. methodological approach framework of modelling when developing a web based gis application, the first step is usually to set up a web server that can handle incoming requests and generate corresponding responses. common open source web servers are apache, nginx and the cherokee http server (apache http server project; nginx http server; cherokee http server project). another main component of the server side is a map server that can provide geospatial data for our application. functionalities of map servers usually rely on ogc’s (open geospatial consortium) standards. the web map service (wms) provides georeferenced map images generated from spatial data (ogc, 2014). wms is mostly used to visualize maps, but basic spatial queries can be also defined to filter data. the web feature service (wfs) can add more functionality to an application since it was designed to transfer the actual geospatial features over the network. unlike wms, this service does not provide a simple image for clients that can be easily shown, so clients must render data to be shown on screen. furthermore, wfs is bidirectional. edits and modification of the database is possible via so-called transactions. this aspect of the wfs is a way to integrate crowdsourcing to an application, where users can add and modify data to a predefined dataset. this way, vgi can be generated through the application and integrated directly into the spatial database. tasks can involve data collection (on screen digitizing) or attribute editing. the most wellknown open source map servers are geoserver and mapserver (geoserver; mapserver). on the client side, different mapping frameworks can be used. openlayers, leaflet and geomajas are most common. they allow users to navigate in an interactive map, but they are also capable of editing geospatial data. a simplified scheme of a web application is shown in fig. 2, where the server side components are marked in green. clients can connect to a webserver, which runs on a host machine. other software components, like a map server can be installed on the server machine. applications with architecture of fig. 2 are not too sophisticated. they provide the simplest functionality possible. however, complex gis analysis or modelling tasks requires application to use complex gis functionality. ogc’s web processing service (wps) standard can enlighten the application with all the gis analysis functions and methods needed by running a backend software on the server machine and providing results to the client. some map servers (such as geoserver) have a built-in wps implementation with a few simple algorithms. there are also standalone wps implementations independent from map servers. an open source solution is developed by 52 north's (52north) geoprocessing community. this wps implementation can work with different backends (such as grass gis or the sextante library). sextante and grass gis are commonly used full gis packages with large collections of spatial analysis algorithms. wps allows the web gis application to use the whole functionality of such packages from a web browser. based on these protocols, a prototype application for disaster management has been developed, with one of the stages already in operation (podolcsák and juhász, 2013). fig. 2 generalized architecture of a web gis application the prototype application as for modelling inland excess water coverage, a web gis application can offer support in the mitigation phase of disaster management (fig. 1). it is of interest whether it is possible to fulfill the data requirements of such application by crowdsourced data. in theory, an engaged and well-trained community can provide relevant information in compliance with the predefined quality and technical 18 juhász et al. (2016) standards. inappropriate operation of rain diversion systems (including ditches, dams, drainage channels) highly influences the formation of inland excess water (szatmári et al., 2011). local farmers know the current conditions of such systems around their land. relevant parameters can be the width, depth of the channels, or even their existence. it is very unlikely that the individuals who work on their fields every day have no such information. on the other hand, this data is difficult to obtain from other sources, therefore it is beneficial to gather this information from them. it is a mutual benefit, because they are also affected by inland excess water formation since it can cause either profit or loss. proactive actions, like modelling water coverage for different rain events, based on the condition of rain drainage systems can result in more effective agricultural activities as well. the prototype application enables users to add and edit ditches in agricultural lands. furthermore, it shows the likely water cover for various fictional scenarios. these scenarios are different from each other based on rain intensity and soil humidity. the outputs from the modelling also use the current geodata of the ditch system previously provided by users, therefore it is dynamic. users can then visually interpret the changes in water cover and the influence of the ditch system. each individual then may or may not decide whether further actions are needed near their lands (podolcsák and juhász, 2013). the application is a technical demonstration, where the authors wanted to prove that it is possible to develop an open source, community based web gis application to support disaster management. algorithms used to calculate the possible water cover may not be accurate, but this was not an objective of the research. it is also important to note that possible users of the application most likely have very limited gis expertise, if any. in this manner, data input methods and the visual outputs have to be as easy to understand and use as possible. in addition, since non-professional users are more likely to generate inaccurate data, data quality will be a major factor. this aspect needs to be further addressed. it is likely that applying quality assurance techniques are necessary, such as filtering and automatic correction will improve the overall accuracy of this application. wps processes the framework was developed using solely free and open source software components. the client side is based on the openlayers library including some custom solutions. server side components are the apache web server, a mysql relational database, geoserver, apache tomcat servlet engine, a wps implementation and grass gis as the geospatial modelling engine in the background. using the 52north wps implementation enables our application to use almost the entire functionality of grass gis. this method is able to handle any type of gis tasks in a web environment. in other words, traditional and highly complex gis functionality can be achieved “directly” in a web browser (podolcsák and juhász, 2013). figure 3 shows the multitier architecture of our prototype application. users access the application via the user interface allowing them to draw new ditches and modify attributes of the drainage network. users can view the predicted extent of water cover while browsing the user interface. data modifications are sent as wfs requests towards geoserver, whereas running simulations are fig.3 multi-tier architecture of the prototype open source web gis solutions in disaster management … 19 sent as wps requests towards grass gis. these requests are defined according to the wfs and wps specifications and they run asynchronously via ajax (asynchronous javascript and xml). using the ajax technique ensures the continuous operation of the application, since users do not have to wait for a process to finish, they are still able to use the application. geospatial tasks (modelling inland excess water cover) are transferred over the network as wps processes. a flowchart of a request-response pairs can be seen on fig. 4. the model was built using the following data layers: dtm (digital terrain model), runoff conditions, participation rate, infiltration rate and surplus surface water. the surface water flow direction and the area of surface water patches were determined based on the derivates of dtm. for the modelling a layer of soil types and another layer of surface cover types were also used. based on these the infiltration rate (in mm/h) was calculated. the surplus of water values were calculated using soil types, surface covers and precipitation rate. although factors that have influence on the formation of inland excess waters do not change within such short time (pálfai, 2004), it can be suspected that ditches choked with weed or artificial barriers prevent residual water from flowing away. this means that near real time analyses can also be useful. possible users of this application can be anyone affected by inland excess water, like local farmers, local government or hydrological professionals (podolcsák and juhász, 2013). modelling the results the system supports two main business processes: the creation and update of the data model and the management of the environment (mitigation of risks and utilization of surface water). in the back-end (system administration), the developers or experts process the data, the modelling and manage the users. firstly, the gis model will be set up, which will make an initial analysis based on input data, using grass gis modules (v.to.rast, r.grow, r.slope.aspect, r.buff, r.sim.water, r.math (r.mapcalc)). the initial analysis will help to optimize the model for quick update to perform the pre-processing of analysis. the pre-processing of analysis step is linked to the analysis/planning part of the front end (end users’ functionality) process, to visualize existing probabilities of hazards. the local community members, farmers can view the other relevant maps in the platform. after visualization, the end users can plan or analyze intervention against the hazard. additionally, in the user community management the end users can harmonize and discuss the plan/analysis intervention phase together in order to make actions to mitigate risk in the intervention phase. if the users decide on mitigation actions the pre– processing of analysis can be performed again and the existing risk can be visualized in analysis/planning phase with the new parameters. in the back-end system administration section, a feedback system, ensures the integration of new parameters in to the model. fig. 4 flowchart of wps processes 20 juhász et al. (2016) model outputs highly depend on the quality of input data. the accuracy of the input digital terrain model (dtm) is crucial to determine surface flow directions. currently, the application uses a dtm derived from elevation information in the 1:10,000 scale hungarian topographic maps. since the application tries to model local differences in water coverage, a more detailed terrain model would be beneficial, such as dtms from aerial laser/lidar scanning (als) or stereo photogrammetry (szatmári et al., 2013). crowdsourced data is also present in the application since the properties of the ditch system can be edited by the community. they can also add or remove and modify sections. this data is used to make changes to the original dtm. this dtm modification based on the width, length and slope of the ditches will allow residual waters to “flow away”. furthermore, these ditches will lower the amount of residual waters along them. figures 5 and 6 show the possible water coverage in the application. fig. 5 represents a scenario where ditches (dotted lines) have no influence on the formation of inland excess waters. three major water patches can be identified on the picture visually regardless to the position of the ditches. this can be a real scenario in case of buried ditches when ditches are blocked by vegetation or other artificial barriers. it can also be seen that patterns and position of residual water align to the system of the point bar, and infill the lower parts. fig. 6 illustrates a scenario where ditches along roads have influence on the formation of residual waters. it is quite visible that the extent of water cover decreased due to the influence of ditches in this area. fig. 5 inland excess water cover seen on the application without the effect of the ditches fig. 6 inland excess water cover seen on the application with the effect of the ditches users can now decide whether it is worth widening or digging ditches along their agricultural lands based on the visual results of the modelling with the new or modified ditch network. in this way, the application helps proactive decisions to be made to prevent inland excess waters. as we previously mentioned, using a more detailed dtm would be beneficial to get more accurate results. furthermore, a vector based network analysis would be more ideal for modelling water flow in ditches. discussion and conclusions disaster management can describe the tasks and utilities of an organization that deals with disasters and emergency situations. information is crucial for making effective decisions, because disasters can affect both lives and properties. although disaster managers mostly rely on traditionally sourced, high quality data, this is not always available. volunteered geographic information or crowdsourced geodata is a new trend in our field. this kind of data is the product of the so called web 2.0, in which non-professional users became creators and providers of spatial information. although this data is heterogeneous and lacks traditional quality assurance, it can be valuable because the shortage of data also limits effective decisions of disaster/emergency managers. therefore creating web applications that integrate vgi data sources into existing ones is an interesting research topic of recent years. using free and open source software to develop geospatial applications is beneficial for many reasons. they are valuable for companies and application developers not just because of the low financial costs, but also the shorter development cycles, as well as the often helpful and fast developing user community, that can help solve problems. open source softwar e is widely used in many areas. numerous gis solutions exist that can compete with commercial products. the use of web processing service solutions is an interesting and promising direction for our field. it allows web applications to use complex gis functionality over the internet. it allows web gis applications to move from an interactive map towards a fully functioning spatial processing framework in a web browser. the authors have developed a prototype application, which proves that a web gis applicatio n can be developed to integrate the ideas of crowdsourcing and gis, therefore can possibly create valuable vgi. the application is useful for disaster management since it can model possible extent of inland excess waters. the application was developed using free and open source software solutions. it contains an easy-to-understand user interface with interactive maps and the possibility of editing features. users can add new features or modify existing ones. data generated this way can be considered as vgi or crowdsourced geographic data and it is used in the modelling process. furthermore, it uses the wps standard to execute a complex gis analyses. previously this kind of functionality was unknown for web gis applications. open source web gis solutions in disaster management … 21 the application is a technological demonstration of integrating available software components. it clearly shows that free and open source software is capable to provide full gis functionality and to generate valuable geographic information over the internet. quality assurance of the generated data and refinement of the used algorithms to create a more correct model is a challenging task for the future. it can be expected that the number of such application will arise in the near future since the technology does not limit the possibilities. standards and software components are freely and easily available. considering the numerous expansion option of prototype it should be remembered that the underlying principles can be applied in the other section too, like in e.g. agriculture, environmental protection, rural development. references alparslan e., ince, f., erkan, b., aydöner, c., özen, h., dönertaş, a., ergintav, s., yağsan, f.s., zateroğulları, a.,. eroğlu, i., değer, m., elalmış, 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(last visited: may 2016) barnier, m. 2006. for a european civil protection force: europe aid. report. european commission, brussels, http://ec.europa.eu/archives/commission_2004-2009/president/pdf/rapport_barnier_en.pdf cherokee http server project http://cherokee-project.com/, (last visited: may 2016) geoserver http://geoserver.org/ (last visited: may. 2016) ksh – központi statisztikai hivatal/hungarian central statistical office 2014. proportion of households with broadband internet connection. http://www.ksh.hu/docs/hun/eurostat_tablak/tabl/tin00089.html (last visited: february 2016) mapserver – http://mapserver.org/ (last visited: may. 2016) nginx http server https://www.nginx.com. (last visited: may 2016) ogc – open geospatial consortium 2014. ogc® standards and supporting documents http://www.opengeospatial.org/standards (last visited: february 2016) unisdr – united nations office for disaster risk reduction. 2014, http://www.unisdr.org/we/inform/terminology (last visited: february 2016) ushahidi https://www.ushahidi.com (last visited: february 2016) 52north http://52north.org/communities/geoprocessing/wps/ (last visited: february 2016) drought monitoring with spectral indices calculated from modis satellite images in hungary journal of environmental geography journal of environmental geography 8 (3–4), 11–20. doi: 10.1515/jengeo-2015-0008 issn: 2060-467x drought monitoring with spectral indices calculated from modis satellite images in hungary andrás gulácsi1*, ferenc kovács2 1institute of environmental sciences, university of szeged, pob. 653, h-6701 szeged, hungary 2department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: gulandras90@gmail.com research article, received 3 september 2015, accepted 28 october 2015 abstract in this study a new remote sensing drought index called difference drought index (ddi) was introduced. ddi was calculated from the terra satellite's modis sensor surface reflectance data using visible red, near-infrared and short-wave-infrared spectral bands. to characterize the biophysical state of vegetation, vegetation and water indices were used from which drought indices can be derived. the following spectral indices were examined: difference vegetation index (dvi), normalized difference vegetation index (ndvi), enhanced vegetation index (evi), difference water index (dwi), normalized difference water index (ndwi), difference drought index (ddi) and normalized difference drought index (nddi). regression analysis with the pálfai drought index (padi) and average annual yield of different crops has proven that the difference drought index is applicable in quantifying drought intensity. however, after comparison with reference data ndwi performed better than the other indices examined in this study. it was also confirmed that the water indices are more sensitive to changes in drought conditions than the vegetation ones. in the future we are planning to monitor drought during growing season using high temporal resolution modis data products. keywords: drought, remote sensing, modis, monitoring, spectral indices introduction climate change is one of the most significant issues facing the world because it is predicted to alter climate patterns and increase the frequency of extreme weather events. in recent years, the frequency of droughts that are due to global warming-related climate change has increased and is accompanied by a rise in the severity of these phenomena (ipcc, 2013; trenberth et al., 2014). in our days – also in the carpathian basin – one of the environmental problems waiting for solution is water shortage, which is one of the biggest hazards, that causes serious damages especially in agriculture in droughtstricken years (rakonczai, 2011). we are talking about water shortage if water supply falls short on human demand and wildlife needs. it can be caused by the limitations of available resources or the insufficient level of utilization of those or/and the increase of society’s needs. according to the guide of the international commission on irrigation and drainage (icid), when precipitation cannot satisfy water needs, because there is a big deficit compared to normal or expected, which extends to growing season, or longer periods too, then there is drought. it is hard to define the beginning and the end of droughts and quantifying its effects. meteorological drought is characterized by the substantially less rainfall compared to multi-year average, this coupled with air temperatures exceeding the average and low relative humidity. this directly affects agricultural production (agricultural drought), which is most often visible on the physiological condition of plants to the naked eye, or can be seen from satellite above. depending on the duration and the strength of meteorological drought, the soil moisture content decreases to the fraction of available water capacity (soil drought). if the catchment area is hit by meteorological drought, runoff and water level of reservoirs, lakes and rivers decreases which is called hydrological drought. the magnitude of drought is influenced by local conditions, e.g. more porous, thicker topsoil can absorb and store more usable water (heim, 2002; pálfai, 2004; hao and singh, 2015). in addition to the economic damage caused by persistent drought, social damage can occur too (e.g. high prices, restrictions of water usage), as well as drought could amplify the existing vulnerability of the social classes (wisner et al., 2004). there is socioeconomic drought when demand for economic goods, as the result of deficit connected to water supply, exceeds the human supply (wilhite and glantz, 1985). the hungarian economy is frequently hit by droughts which are partly due to the unexploited water potential. drought is a relative rather than an absolute condition that needs to be interpreted separately in every region and on every group of organisms. every drought differs from one another in intensity, duration and spatial extent. in agricultural point of view, drought is a substantial degree of water shortage of stand of croplands and forests which greatly limits the life processes of 12 gulácsi and kovács (2015) plants. without a plant drought cannot be interpreted since different plant species react distinctly to the same level of drought (anyamba and tucker, 2012). with the drought assessment in a quick and costeffective way, with even the possibility of forecasting, it may become possible to increase adaptability of water retention. optimization of the redistribution of water resources may become possible if location is known where greater need for them is. we could prepare for drought or at least moderate its damages by filling up reservoirs (partially) satisfying irrigation and ecological needs if necessary. remote sensing methodology provides one of the ultimate tools that support the water management organizations’ operational work vulnerability and some indicators of drought risk is the combination of the probability of an event and its negative consequences which is the intersection of hazard, vulnerability and exposure. vulnerability which is inversely related to coping capacity is the characteristics and circumstances of a community, system or asset that make it susceptible to the damaging effects of a hazard (unisdr, 2009). in drought monitoring there are many meteorological-statistical method and remote sensing based indices; more than a hundred of them is known (faragó et al., 1993; zargar, 2011). the one developed by palmer (1965) in the us, which is calculated from precipitation, temperature and soil moisture content data, is the so-called palmer drought sensitivity index (pdsi) that has been used in hungarian study areas too (horváth, 2002). for the standardized precipitation index (spi) at least 30 years long precipitation dataset is needed. the gamma distribution fitted on the empirical probability distribution of the dataset has to be transformed to normal distribution; the probabilities are the spi values (mckee et al., 1993). this analysis method is very popular (hayes et al., 2012) in hungary too (dmcsee, 2010-14; blanka et al., 2014). mu et al. (2013) used a drought index called drought severity index (dsi), which can be generated from the ratio of evapotranspiration and potential evaporation (et/pet), resp. normalized difference vegetation index (ndvi), for modis sensor data. the basic version of pálfai drought index (pai), which is commonly applied in hungary, is calculated from meteorological (daily temperature and precipitation) datasets and we get its actual value when we multiply its base value with empirical correction factors (pálfai, 1989). fiala et al. (2014) are analyzing the simplified version of pai (padi) in hungarian and serbian areas with gis processing; padi is calculated from monthly average temperature and monthly average precipitation dataset. spectral indices derived from measurements of multispectral sensors like the ones analyzed in our study could be a great addition to their method as well. kovács (2007) and ladányi et al. (2011) identified high drought risk areas based on time series of biomass productivity from normalized difference vegetation index (ndvi) and enhanced vegetation index (evi) data and study area drought indices calculated from terra modis satellite images may become suitable in monitoring short term spatiotemporal variations in drought intensity at regional scale. high temporal resolution allows analyzing environmental change processes. in the course of data processing, several pre-calibrated and evaluated products are manufactured which are available free of charge (e.g. glovis database). modis-composites are compiled from the optimal selection of pixel values of satellite images recorded during the period of 8 or 16 days. cell values of composites are always made of the best data quality pixels available (huete et al., 2002; vermote and kotchenova, 2008). selection covers the viewing and illumination geometry, the state of the atmosphere and the amount of cloud cover e.g. the first half of july is one of the most suitable dates, because precipitation in this month has the maximum weight since plants require a lot of water in july. in addition, the occurrence of a drought is the most likely in this month (pálfai, 2004). however, after harvest it is inappropriate to choose a date, because harvested croplands can be classified as drought-stricken (e. g. time range of wheat fig. 1 hungary, the study area drought monitoring with spectral indices calculated from modis satellite images in hungary 13 harvest in hungary is from the end of june to middle of july). for our analysis we have chosen two dates: one from june and another one from july (fig. 1). for the calculation of spectral indices mod09a1 (collection 5) 500 m resolution 8-day surface reflectance composite images (surface reflectance 8-day l3 global 500m sin grid) between 2000 and 2014 were used (table 1). spectral band values are multiplied by a factor of 10,000. images are from the 9-16th (resp. 10-17th) of june (resp. 10-17th) and the 12-19th (resp. 11-18th) of july. in some instances different periods were chosen because of high cloud cover. the 16-day 500 m resolution evi composite images (mod13a1 evi, vegetation indices 16-day l3 global 500m sin grid) were obtained for the period of 9-24th (resp. 10-25th) of june and of 11-26th (resp. 12-27th) of july. records from the modis catalog h/v 19/4 (lat/long 45/21.1) were downloaded from glovis database [1]. the composites are not allowing observing changes on daily scale or less than 8 or 16 days long time periods, but they are still very good at monitoring changes for longer periods. table 1 spectral bands of mod09a1 surface reflectance 8-day composites (vermote and kotchenova 2008) mod09a1 bands wavelength (nm) 1 (visible red) 620-670 2 (near infrared) 841-876 3 (visible blue) 459-479 4 (visible green) 545-565 5 (swir 1) 1230-1250 6 (swir 2) 1628-1652 7 (swir 3) 2105-2155 swir: short-wave infrared quality control and state flag created for the spectral bands provide information about each pixel’s data quality, accuracy and consistency (e.g. cloud cover and cloud shadow, dead detector and data interpolated, value out of bounds, aerosol quantity of the air, zenith angle of sun). the quality control and state bands are storing metadata as decimal numbers which have to be converted into 16, resp. 32 bit binary series to extract information needed for pixel evaluation. before using modis data, incorrect, inaccurate or inconsistent pixel values have to be excluded from analysis. the processing tools (ldope tools and modis reprojection tool) provided by the modis land quality assessment group (roy et al., 2002) were applied at the extraction of quality, cloud cover and cloud shadow mask from the 16/32 bit binary quality and state bands. general rule is that the lower the value, the better the quality. zero means that there are no quality issues. the pixel values defined as incorrect were overwritten by the pre-defined no data value of spectral bands (−28,672). for the execution of this operation a program was written in c language (named modis quality control tool) which reads in data in ascii grid file format. we have taken the following bits into consideration with the conditions for pixel evaluation shown in table 2. the predefined no data value for mod13a1 data is −3000. the strictness of specified conditions in case of mod09a1 and mod13a1 data are very much alike. data accuracy is determined by inaccuracies of cloud filtering, variable viewing and illumination geometry, different amount of cloud filtered data for averaging, inaccuracy of atmospheric correction. database can also be cleaned if we are not taking into consideration satellite passes with higher than 40° zenith angle or providing less than 25% data coverage (huete et al., 2002). data processing and analysis was performed in opensource geospatial software environment, the following programs were used: saga gis 2.1, qgis 2.4-chugiac (python 2.7.5, gdal 1.11.0 and grass gis 6.4.3 integrated into qgis), r for windows 3.1.2, modis reprojection tool 4.1, ldope tools 1.7, and own programs written in c language in code::blocks 10.05 environment. processing was automatized by the use of scripts. methods characterization of spectral indices a new method for drought delineation using modis surface reflectance data was presented in the paper by gu et al. (2007). it is called normalized difference drought index (nddi). nddi (eq. 1) is derived from ndvi and ndwi (normalized difference water index): nddi = (ndvi − ndwi) / (ndvi + ndwi) (eq.1) where: ndvi = (nir858 nm − red645 nm) / (nir858 nm + red645 nm), ndwi = (nir858 nm − swir2130 nm) / (nir858 nm + swir2130 nm), nir: near infrared, swir: short wave infrared. table 2 pixel evaluation of modis satellite images using the quality assessment bands mod09a1 mod13a1 state flags: 0-1. bits: cloud state (=0) 2. bit: cloud shadow (=0) quality control: 2-5. bits: 1st band’s data quality (=0) 6-9. bits: 2nd band’s data quality (=0) 26-29. bits: 7th band’s data quality (=0) vi quality detailed qa: 0-1. bits: vi quality (modland qa bits) (<=1) 2-5. bits: vi usefulness (<=4) 15. bit: possible shadow (=0) pixel reliability qa summary (<=1). 14 gulácsi and kovács (2015) ndvi was developed by rouse et al. (1973), and it has been in use for decades for monitoring vegetation cover, chlorophyll content and other properties of the plants. absorption of healthy vegetation is very high in the visible wavelength range. on the other hand, the near infrared channel is located at the high reflectance plateau. dry and unhealthy vegetation canopy has lower ndvi value because reflectance in the visible red channel is increased, simultaneously in the nir channel decreased. if chlorophyll content is high, then it means that the plant is photosynthetically very active, which means high absorption in visible red and high reflectance in nir channels. ndwi represents the water content in vegetation canopies. absorption by vegetation liquid water around 858 nm (nir channel, at the high reflectance plateau of vegetation canopy) is negligible, while at around 2130 nm it is very high. if water content decreases, then in swir channels reflectance increases significantly, therefore the ndwi value decreases showing dry vegetation under drought stress. chen et al. (2005) used spectral indices calculated from nir858 nm and swir1640 nm, respectively swir2130 nm bands of modis reflectance data for the estimation of moisture content of corn and soybeans. both showed potential in estimating vegetation moisture content. this ndwi is the variation developed by gao (1996). the study conducted by gu et al. (2007) showed that ndwi has a stronger response to drought conditions than ndvi. the average of ndvi and ndwi were consistently lower (ndvi<0.5 and ndwi<0.3) under drought conditions than under nondrought conditions (ndvi>0.6 and ndwi>0.4) at shallow, turbid waters the water-leaving reflectance at nir is not negligible, and is not only related to phytoplankton abundance, but also to suspended sediment concentration. atmospheric correction of modis (the “clear water” assumption) fails in the presence of even modest quantities of suspended particle matter, because nir water-leaving reflectance is not negligible, and is not related to phytoplankton abundance (chen et al., 2013; wang et al., 2013). because of that, some parts of water surfaces are being classified as drought-stricken in case of ndwi and the drought indices. it is the reason why the area of lake balaton was excluded from our analysis. during calculation of nddi, most of the values are transformed into an interval between −1 and +1, however in spite of quality control extreme out of range values are generated too that makes statistical analysis useless. with the use of difference drought index (ddi) the emerging of extreme out of range values was avoided. it is the reason we calculated simple difference index without normalization (eq. 2): ddi = dvi – dwi (eq. 2) where: dvi (difference vegetation index) = nir858 nm − red645 nm, dwi (difference water index) = nir858 nm − swir2130 nm. the lack of normalization, which gets rid of the differences in spectral radiance resulting from different illumination angle and slope, is the only disadvantage ddi has, but the greater part of hungary is lowlands with the dominant land use of croplands, therefore it is a small concern. the enhanced vegetation index (evi), as an optimized hybrid index, combines the characteristics of the atmospheric resistant index (arvi) and the soil adjusted vegetation index (savi). evi is an ndvi variant with correction factors for minimizing atmospheric effects and removing soil-brightness induced variations (solano et al., 2010). the evi formula is written as (eq. 3): evi = g · ((nir858 nm–red645 nm) / (nir858 nm+c1·red645 nm +c2·blue469 nm+l)) (eq. 3) where nir, red and blue band values are atmosphericcorrected (for rayleigh scattering and ozone absorption) fig. 2 the connection between dvi and dwi on the examined date in july drought monitoring with spectral indices calculated from modis satellite images in hungary 15 surface reflectance; l is the canopy background adjustment for correcting nonlinear, differential nir and red radiant transfer through a canopy; c1 and c2 are the coefficients of the aerosol resistance term (which uses the blue band to correct for aerosol influences in the red band); and g is a gain or scaling factor. the coefficients adopted in the evi algorithm are, l=1, c1=6, c2=7.5, and g=2.5. statistical connections between dwi-dvi and ndwindvi relationships between dwi-dvi and ndwi-ndvi were unfolded using linear regression analysis which we run for a random sample of 500-600 pixels. we used the same random pixels for each date. there is a strong link between dwi and dvi; coefficients of determination vary from 0.88 to 0.95 in june, and 0.92-0.96 in july. connection between ndwi and ndvi is weaker, coefficients of determination show greater variability (r2 are 0.66-0.85 for june and 0.78-0.91 for july) (fig. 2). ndvi has been applied for decades in vegetation monitoring (rouse et al., 1973). high correlation has proved water indices to be capable of quantification of droughts. there is a strong connection between chlorophyll and moisture content of vegetation canopy for which are vegetation and water indexes proxies that proves the usability of water indices. results spatial extent of drought-stricken areas based on ddi and ndwi when defining the value range of drought classes one huge advantage cluster analysis or other automatic classification algorithms have that we extract information from data without subjective interference. we used a cluster analysis method by forgy (1965) called iterative minimum distance for ddi data. best results were obtained when setting eight outgoing clusters. before the first iteration data was normalized with standard deviation. separate classes were created, each containing pixels with similar drought intensity. we calculated the ddi average for each date and the average of all june and july records between 2000 and 2014 (ddijune=505.67 and ddijuly=520.95). if ddi mean exceeds these thresholds than the given time period is considered to be drought-stricken. based on the rule june was drought-stricken in 2000, 2001, 2002, 2003 and 2009, and in case of july in 2000, 2001, 2002, 2003, 2007, 2009, 2012 and 2014. after that we averaged the ddi averages of drought years (ddijune=578.86 and ddijuly=586.25) to get the drought threshold limits of ddi. the cluster mean of drought clusters exceeds these threshold limits. the difference between the average of drought and non-drought years referring to time series of the two months is 122 and 140 (june and july respectively). based on class means we separated 4 drought intensity categories from the classes in the examined periods (table 3). the ddi threshold of july (650) based on the cluster means between drought and non-drought is higher than the average of ddi (586) in drought years. the average of dwi, which is one of the factors influencing ddi values, is 1856 in drought years while it is 2197 in mild and wet years in july. in case of dvi, the other factor, these values are 2442 and 2639 respectively. by the differences dwi reacts more sensitively to drought condition than dvi. in case of the june values compared to the july ones dwi shows less, but still higher difference (189) between drought (2082) and non-drought (2271) average than dvi (difference is 107. water indices are more sensitive to drought conditions than the vegetation ones. in order to utilize the high sensitivity of water indices we calculated the drought categories based on the vegetation liquid water content for ndwi too (table 3). table 3 created drought categories based on ddi and ndwi ddi categories description ddi <0 wet, water cover 0<= ddi <650 no drought 650<= ddi <812 weak drought 812<= ddi <1053 moderate drought 1053<= ddi <1319 strong drought 1319<= ddi very strong drought ndwi categories description 0.7<= ndwi very high moisture content 0.6<= ndwi <0.7 high moisture content 0.6<= ndwi <0.5 moderate moisture content 0.4<= ndwi <0.5 low moisture content 0.3<= ndwi <0.4 weak drought 0.2<= ndwi <0.3 moderate drought 0<= ndwi <0.2 strong drought ndwi <0 very strong drought after defining drought categories for ndwi, we excluded the weak drought class because compared to ddi we would have overestimated the spatial extent of droughts. in case of ndwi pixels with value under 0.3 are considered to be drought-stricken. the results from ddi and ndwi coincide very well (r2=0.91). spatial extent of droughts for july is shown in fig 3. average spatial extent of drought according to ddi was 22,778 km2 in july. average area was exceeded in 2000, 2001, 2002, 2003, 2007, 2009, 2012 and 2014. spatial extent of drought was lowest (7,669 km2) in 2005 according to ddi, but in case of ndwi in 2004 (7,454 km2). the biggest drought was in 2007 which hit 42,452 square kilometers according to ddi. on the other hand ndwi showed that the spatial exte nt of drought was greatest in 2000 (35,846 km2), however area hit by strong and very strong drought peaked in 2007 (in case of ddi the moderate drought areas culminated as well). in the ranking 2007 and 2000 are followed by 2003 and 2002 in july. 16 gulácsi and kovács (2015) fig. 3 extent of drought affected areas in july according to ddi fig. 4 geographic distribution of drought areas according to ddi in july drought monitoring with spectral indices calculated from modis satellite images in hungary 17 ddi averages in june and in july show a great divergence in 2007 indicating that drought appeared first in july. in contrast, drought in 2003 was noticeable too. the difference between consecutive years stands out in 2003-2004 and in 2006-2007. in addition, higher annual variability between 2006 and 2010 is worth for mentioning. geographical distribution of drought based on ddi and ndwi in july are shown on fig. 4 and 5 where the high vulnerability of danube–tisza interfluve stands out very well. comparison of results with reference data to test the validity of spectral indices we analyzed their relationship with the pálfai drought index (pai) for the whole country and for the great plains only. based on pálfai (2011) the western border of the great plains was set to the midstream of river danube. pai data was obtained from the discussion paper of the national drought strategy (hungarian ministry of rural development 2012). we compared the spectral index averages with the following reference data provided by cso [2, 3]: crop yields of cereals (wheat, durum wheat, rye, barley, oat, triticale, corn, maslin (mixture of wheat and rye), rice, other cereals (indian rice, millet, canary seed, sorghum, buckwheat)) between 2000 and 2013, corn and wheat yields between 2000 and 2012 and irrigation water use of agriculture (labeled as „all sold water for irrigation, rice production included”). these data only applies to agricultural land, therefore we clipped ddi data with the area of the „non-irrigated arable land” category of the corine land cover database (clc2012) [4]. in our current study we could only relate yields of different crops and irrigation data to the area of croplands based on clc2012. because of the lack of available data we could not differentiate between the fields of different cereals. croplands can be identified in the knowledge of the dataset, since crops with similar growing cycle develop in a similar matter in a given year (kern et al., 2014). fig. 5 geographic distribution of drought areas according to ndwi in july 18 gulácsi and kovács (2015) the spectral index values in june did not perform as well as the july ones. the spectral index-pai relationships were weak and statistically insignificant except for ddi and nddi, which performed slightly better (between ddi and countrywide pai r2=0.54, while between nddi and pai for the hungarian plain r2=0.52). the correlations with yield data were very low, except for wheat-evi (r2=0.62) and wheat-dwi (r2=0.62) correlations. no link was found with irrigation water use. on the other hand, spectral indices performed well in july. the drought indices show positive trend with pai; in contrast, vegetation and water indices a negative trend. drought indices and crop yields are inversely related. irrigation water use is directly proportional to ddi and nddi. the opposite is true for vegetation and water indices: direct proportion to pai and to crop yields and inverse proportion to water use. normalized difference indices have a stronger link with reference data compared to simple difference indices, except for ddi which performed similar to nddi (table 4). based on the coefficients of determination in july, not the drought indices performed best, but ndwi. ndwi has the strongest link with pai in case of the area of the hungarian plain, plus a strong one for the whole country as well. strong statistical connections with all cereals’ and corn yields were observed. in addition, ndwi has a moderate high correlation with agricultural water use. dwi is not far behind except for water use. ddi has a strong link with pai, but a weak one with agricultural water use; ddi shows moderate strong correlations with all cereals and corn yields. pai-dvi and pai-evi links were the weakest among the indexes, but evi and dvi show a bit stronger link with corn yield data then ddi or nddi. the ndvi-pai relationship is stronger; in case of all cereal and corn yield data ndvi performed similar to dvi. connections with irrigation water use were mostly weak; highest in case of ndvi and ndwi. in the harvesting period of wheat, we compared the spectral index averages of the harvested fields with the yields too, so the regression results for wheat which are statistically insignificant are not valid for july. discussion although ddi performed adequately in drought detection, it may not be the best choice. on the whole, ndwi shows stronger links to reference data then the other spectral indices. at the evaluation of results we have to take into consideration that crop yields are influenced by a number of environmental factors besides droughts: harvesting date is not constant it varies annually depending on how much precipitation there is, growing degree units plants get, coping capacity or tolerance of different crops, e.g. besides drought, cold and wet weather, inland excess water, pest or an extreme weather event like rainstorm or hailstorm can also damage crop yields. coping capacity of the plants is different; soil properties like fertility, water holding capacity, permeability have an influence on the yield too. strength of the link between spectral indices and crop yields varies between months or years and between different areas as well. the difference drought index detects agricultural drought (via biophysical changes of the plants) whereas the pálfai drought index rather detects meteorological drought (through precipitation and temperature time series). moreover, the distance between meteorological stations is great (up to more than 10 kilometers) so the geometrical resolution of data is significantly less than 500 meters that modis reflectance data provides. differences of spatial resolution may have influenced the tightness of linear fit. on the other hand, because of atmospheric effects some of the pixels had to be excluded from analysis may increase uncertainty of results. for our analysis we have chosen satellite images recorded in a relative cloud free 8 day periods in order to keep errors originating from atmospheric effects at the lowest level possible. conclusions the new remote sensing based difference drought index (ddi) performed above expectations during the analysis which is proven by the strong link between ddi and the pai. even though they combine water and vegetation table 4 performance comparison of indices according to values of the coefficients of determination (r2) in july index pai (hungarian plain) pai (whole country) all cereals [kg/ha] corn [kg/ha] wheat [kg/ha] irrigation water [million m3] mod09a1 ddi 0.87 0.81 0.67 0.63 0.37 0.51 nddi 0.85 0.77 0.65 0.64 0.31 0.48 dwi 0.81 0.75 0.79 0.77 0.47 0.52 ndwi 0.90 0.80 0.80 0.78 0.48 0.64 dvi 0.60 0.62 0.69 0.68 0.42 0.42 ndvi 0.78 0.71 0.72 0.73 0.44 0.64 mod13a1 evi 0.63 0.67 0.81 0.76 0.41 0.35 drought monitoring with spectral indices calculated from modis satellite images in hungary 19 indices, ddi and nddi did not performed better compared to ndwi which is an ultimate vegetation moisture index. our results imply that ndwi, which is a proxy for changes in moisture content of the canopy, reacts to drought conditions more sensitively than ndvi (or the other indices), because in case of a drought water loss occurs sooner than the reduction of chlorophyll content of vegetation. because of its advantages, ndwi may become widespread in hungary. in the future we are planning to monitor drought during growing season using high temporal resolution modis data products in order to see how spectral indices react to seasonal variations of photosynthetic activity and moisture content of vegetation canopy in more detail. acknowledgments this paper was supported by the jános bolyai research scholarship of the hungarian academy of sciences. this paper was supported by támop-4.2.1.d-15/1/konv2015-0002 project. references anyamba, a., tucker, c.j. 2012. historical perspectives on avhrr ndvi and vegetation drought monitoring. in.: wardlow, b.d.; anderson, m.c.; 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drought phenomenon: the role of definitions. water international 10 (3), 111–120. doi: 10.1080/02508068508686328 wisner, b., blaikie, p., cannon, t., davis, i. 2004. at risk: natural hazards, people’s vulnerability and disasters (2nd edition). routledge, london. zargar, a., sadiq, r., naser, b., khan, f. i. 2011. a review of drought indices. environmental reviews 19, 333–349. doi: 10.1139/a11-013 references from the internet [1] http://glovis.usgs.gov, glovis database [2] http://www.ksh.hu/docs/hun/xstadat/xstadat_eves/i_omn007.html a fontosabb szántóföldi növények betakarított területe, összes termése és termésátlaga (1990–) [3] http://www.ksh.hu/docs/hun/xstadat/xstadat_eves/i_uw001.html, mezőgazdasági vízfelhasználás (2000–) [4] http://fish.fomi.hu/letoltes/nyilvanos/corine/clc12_hu.zip, clc2012 database introduction vulnerability and some indicators of drought data and study area methods characterization of spectral indices statistical connections between dwi-dvi and ndwi-ndvi results spatial extent of drought-stricken areas based on ddi and ndwi comparison of results with reference data discussion conclusions acknowledgments references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. i. no. 3-4. pp. 1-6 development of an integrated ann-gis framework for inland excess water monitoring van leeuwen, b. 1 – tobak, z. 1 – szatmári, j. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract inland excess water on the great hungarian plain is an environmental and economic problem that has attracted a lot of scientific attention. most studies have tried to identify the phenomena that cause inland excess water and combined them using regression functions or other linear statistical analysis. in this article, a different approach using a combination of artificial neural networks (ann) and geographic information systems (gis) is proposed. anns are particularly suitable for classifying large complex non-linear data sets, while gis has very strong capabilities for geographic analysis. an integrated framework has been developed at our department that can be used to process inland excess water related data sets and use them for training and simulation with different types of anns. at the moment the framework is used with a very high resolution lidar digital elevation model, colour infrared digital aerial photographs and in-situ fieldwork measurements. the results of the simulations show that the framework is operational and capable of identifying inland excess water inundations. keywords: inland excess water, artificial neural network, geographic information systems introduction inland excess water is a reoccurring problem in the great hungarian plain. at the end of winter large parts of the flat terrain are covered by water. these inundations cause serious economic and environmental problems. several studies have analysed the problem, with varying success (bozán cs. et al. 2005, pásztor l. et al. 2006, rakonczai j. et al. 2001, rakonczai j. et al. 2003). most studies have tried to identify the phenomena that cause the inland excess water and combined them using regression functions or other linear statistical analysis. in this article, a different approach using artificial neural networks (ann) is proposed. this approach has many advantages compared to other statistical methods. first, it is independent of the statistical distribution of the data, and there is no need for specific statistical variables. neural networks allow the target classes to be defined in relation to their distribution in the corresponding domain of each data source, and therefore the integration of remote sensing or gis data is very convenient (pradhan b. – lee s. 2010). certain types of inland excess water can be forecast and those areas or points where action is needed for decreasing or even avoiding damage can be directly determined with the help of theoretical and practical means. this way the risk of inundation can be mitigated in numerous occasions, and this could lead to a shift from a reactive, defensive-type water management strategy towards a more proactive strategy, in order to decrease or even prevent damage. fig. 1 a basic artificial neural network 2 van leeuwen, b. – tobak, z. – szatmári, j. joeg i/3-4 artificial neural networks artificial neural networks are computational models that imitate the functioning of the human brain. several different types of neural networks exist but their basic structure always consists of multiple layers of interconnected nodes (fig. 1). every neuron processes the weighted sum of all inputs, and, via a so-called activation function it is determined if the signal is sent further. the application of anns consists of two phases. the first phase is called the training phase. during this phase the ann is fed with an input and an associate output data set. the training is an iterative process where the weights of the incoming signals are adapted in such a way that the overall average error between the requested output and the calculated results is minimized. the trained network can be used in the second phase where it is fed with new input data to calculate new output results. a more detailed description of anns goes beyond the scope of this article but can be found in retter gy. (2006), hewitson b. c. and crane r. g. (1994) and zurada j. m. (1992). anns have been proven themselves in many fields of science where complex data sets need to be analyzed to identify their underlying structures and properties. neural networks have a large potential for analysis of complex spatial problems which are common in geographic research (hewitson b. c. – crane r. g. 1994). inland excess water inundations on the great hungarian plain are a clear example of such problems. the reoccurring inundations are caused by a multitude of interrelated factors. the connection between the world of neural networks and gis is still relatively new and needs to be developed further (coleman a. 2008, sárközy f. 1998). just two gis software exist that employ fully integrated gis – neural network solutions; arcgis and idrisi. these solutions have been investigated but were not used in this study because they employ only one type of neural network architecture, a multi-layer perceptron and a radial basis function network, respectively, and they do not offer integrated tools for the evaluation of the training and the simulation results. matlab 7.10.0 has an integrated neural network fig. 2 the digital elevation model overlaid with cir mosaics of 24 march 2010 showing the training (a) and simulation (b) area with the gps fieldwork results in the tápairét area joeg i/3-4 development of an integrated ann gis framework for inland excess water monitoring 3 toolbox that ranges from simple solutions to extended neural network implementations. the determination of the network architecture constitutes one of the major and most difficult tasks in the use of neural networks (barsi á. 1997, jafar r. et al. 2010). since it is not exactly known what type of neural network with which settings is most appropriate to study the problem of inland excess water, it was decided to build a framework that facilitates the possibilities to experiment with several neural networks and settings in a gis environment. arcgis 9.3 was used as the gis environment because of its strong capabilities for geographic analysis, and its possibilities for customization. study area and data the great hungarian plain covers an area of 52,000 km 2 . the tápairét area was selected from this region as a test site for the inland excess water research (fig. 2). this study area is about 20 km 2 large and its maximum difference in elevation is 10 meters. mainly agricultural activity takes place in the area, although there are also several oil stations. from the young sediments with high clay content of the maros river, fluvisols and vertisols were formed (marosi s. – sárfalvi b. 1990). because of the extreme mechanical properties – in large areas, the plasticity index (ka) is above 60 (cm 3 /gr) –, the exceptionally bad permeability characteristics result in accumulation of water in the lower areas. table 1 gives an overview of the data used in this research. all data were collected in the period 20092010. apart from the bad soil characteristics, the area consists of very flat terrain with large local depressions, without run-off. the average groundwater level varies between 2 and 4 meters below the surface. remnants of river meanders can also be found in the area. only in the former meanders, the groundwater may reach the surface. this research focuses on the genetic type of the inland excess water that is caused by a lack of runoff and infiltration, and not on the type that is due to high groundwater levels. framework a framework was created to handle input data, intermediate results and output data in a flexible way in both arcgis and matlab (fig. 3). in this way, it was possible to create the data files, test different network types and settings and evaluate the training and simulation results efficiently. first, different artificial data sets were created in arcgis. these data sets were used to set up the framework and to evaluate the simulated results. three artificial input maps of 100 by 100 pixels were created. each map represented specific inland excess water related input parameters (e.g. local depressions, geomorphologic structures, soil types, height of the groundwater table, land use). a forth artificial map was created to represent the occurrences of inland excess water in the same area. the files were created using arcgis 9.3 and were stored in tiff file format. the tiff files were read into matlab resulting in a 100x100 cell matrix for each map. the neural network analyses were performed with the neural network toolbox of matlab. this is an extension of the general matlab functionality incorporating many artificial neural network architectures and tools for training and evaluation of the results (demuth h. et al. 2010). the neural network toolbox needs data in a matrix format where every row represents an input data layer. a program was written to convert the separate input matrices to arrays and to combine the resulting 1x10000 arrays into one matrix with 3x10000 cells that could be read by the neural network toolbox. the output matrix, representing the occurrences of inland excess water was converted to an 1x10000 array as well. with the artificial data, only the standard neural net in the nftool from the neural network toolbox was used. this is a two layer feed forward network with maximum 20 neurons in the hidden layer. a smaller amount of neurons gave similar results but resulted in lower performance due to more iterations. the network was trained table 1 input and output data lidar /dem/ local depressions lidar data with a spatial resolution of 1.4 points per m 2 were collected from a 70 km 2 area during a flight campaign on 19 november 2009. based on this data, a 1 meter resolution digital elevation model was created. cir (colour-infrared) imagery at the maximum of the inland excess water periods, on 24 march and 9 june 2010, flights were executed using a data collection system based on the ms3100 digital camera (tobak z. et al. 2008) to collect 800x600 meter images. from all individual images a 63 cm resolution mosaic covering an area of 60 km 2 was created. field measurements on 5 march, 2010, a one day fieldwork was carried out in the south-western part of the study area. at that moment, the second level on the national inland excess water hazard scale was valid. in total 7.8 ha of inundated land was accurately measured by walking around them using hand-held gps systems. 4 van leeuwen, b. – tobak, z. – szatmári, j. joeg i/3-4 with 70% of the data, while 15% was used for validation and 15% for testing. the optimal network was saved to be used in the simulation phase. simulation data was then imported from the gis, converted to a matrix and fed to the neural net. fig. 3 framework showing the workflow in arcgis and matlab the simulation result was again converted into a matrix. during the different conversion steps the data had to undergo various types of conversions to be compliant with the particular data formats. finally, a continuous 8 bit tiff file was generated which could be visualized in arcgis. apart from several pre-processing steps, the same workflow, as described above with the artificial data, was followed using the new, real data set as well (fig. 4). the training data consisted of 4 input and one output layers. the colour infrared images were split in three bands; green, red and near infrared. using the fill tool in arcgis, the local sinks in the lidar based digital elevation model were filled (tarboton d. g. et al. 1991). the original height values were subtracted from the sink map, resulting in a layer with the local depressions. the depression map was reclassified into three classes: very small depressions (<15 cm), middle (15-60 cm) and deep (>60 cm) depressions. the resulting map was used as the forth input layer in the training phase. the fieldwork measurements were rasterized and used as output map during the training. that time only two output classes were defined: open water and dry soil. every data layer had a spatial resolution of 1 meter and was covering an area of 1000x1000 meter. during the simulation phase the same type of cir imagery and elevation data were used. the same preprocessing steps were executed as in the training phase; just the location of the data was several hundreds of meters further to the north (fig. 2). fig. 4 the pre-processing of the training data results several settings for the number of neurons in the hidden layer were tested. with an increase of the neurons, the rmse decreased, however, the performance of fig. 5 the results of the training (left) and the simulation (right) joeg i/3-4 development of an integrated ann gis framework for inland excess water monitoring 5 the training also decreased sharply. an optimum of 10 neurons was selected resulting in an overall rms training error of 0.74. the result of the training is shown on the left side of fig. 5. the right side of fig. 5 shows the result of the simulation using the trained network. the yellow areas were classified as inland excess water. in the northern and north-western part of the area the results are good. the open water along the levee and the roads was detected. the inland excess water in the southern part of the images is not properly classified. some pixels are correctly indicated as inland excess water but the majority is classified as dry land. these errors are probably due to the composition of the training set, where only water was incorporated but saturated soil and vegetation in water were omitted. a second simulation was executed using the same trained ann, but this time with different multi-spectral data. in this simulation, the colour infrared images collected on 9 june were combined with the same local depression data that was used in the first simulation (fig. 6). although in general, the inland excess water areas that were identified on the images taken on 24 march, were also classified as water on the images taken on 9 june, on the second date much more inland excess water was detected. furthermore, the second simulation shows that there is scattered water on the large parcels in the centre of the images. this may indicate that the soil in this area was completely saturated with water. since no ground truth was collected for the area at the time of the data acquisition, it is not possible to quantify the simulation differences. fig. 6 the simulation results of two different times: 24 march 2010 and 9 june 2010 fig. 7 comparison of different classification methods: maximum likelihood (left), minimum distance (middle), artificial neural network (right). white colour indicates inland excess waters, all other areas are in black. the training data is shown with a red-coloured boundary 6 van leeuwen, b. – tobak, z. – szatmári, j. joeg i/3-4 a comparison has been executed among the training results of the ann and two traditional classification methods: maximum likelihood and minimum distance (fig. 7). the ann classification clearly shows the white area overlapping with the training area. several other patches of inland excess water were also classified. for these areas no ground data was collected but they can easily be identified visually on the cir images (fig. 2/a). for the other two classifications only the pixels of the training area were used during the supervised training. for both traditional classifications this results in accurate classification of the inland excess water in the training data, but also in an extreme over-classification in the areas outside this area. conclusions the framework works as expected with a small artificial test data set. the larger real data set also resulted in proper delineation of inland excess water, but further development is still needed. due to the nature of spatial data, very large matrices are created as input data for the network. this results in performance problems. by reducing the amount of input pixels in the input data sets, the performance of the system can be improved. the result of the simulation shows a clear distinction between water and dry soils. in reality this is a fuzzy boundary. intermediate classes like saturated soil and vegetation in water also exist. these classes were not taken into account in the training set. extra field data will be needed to incorporate these classes and to be able to derive them in the simulation. this fieldwork data is also needed to be able to quantify the differences in results between the different classification methods. furthermore, other input data sources, like soil maps, hydrological maps can be incorporated to extend the base of the training set. finally, the integration between the gis and the neural network has to be improved. the framework now consists of several loosely coupled programs and matlab functions. to facilitate the most efficient prototyping their integration is inevitable. acknowledgement this study was financially supported by the project “development of an inland excess water-info system” (economic operative program: gop 1.1.1 08 / 1 -2008 – 0025). references barsi á. 1997. landsat-felvétel tematikus osztályozása neurális hálózattal. geodézia és kartográfia 49/4: 21-28 bozán cs. – pálfai i. – pásztor l. – kozák p. – körösparti j. 2005. mapping of inland excess water hazard in békés and csongrád counties of hungary. icid 21st european regional conference 2005 – 15-19 may 2005. frankfurt (oder) and slubice – germany and poland coleman a. m. 2008. an adaptive landscape classification procedure using geoinformatics and artificial neural networks. unpublished msc thesis, amsterdam. 195 p demuth h. – beale m. – hagan m. 2010. neural network toolbox 6, user’s guide. the mathworks 901 p hewitson b.c. – crane r.g. 1994. neural nets: applications in geography. dordrecht: kluwer academic publishers. 194 p jafar r. – shahrour i. – juran i. 2010. application of artificial neural networks (ann) to model the failure of urban water mains. mathematical and computer modelling 51: 11701180 marosi s. – sárfalvi b. 1990. magyarország kistájainak katasztere i. budapest: mta fki. 1023 p pásztor l. – pálfai i. – bozán cs. – kőrösparti j. – szabó j. – bakacsi zs. – kuti l. 2006. spatial stochastic modelling of inland inundation hazard. 9th agile conference on geographic information science. visegrád, hungary pradhan b. – lee s. 2010. landslide susceptibility assessment and factor effect analysis: backpropagation artificial neural networks and their comparison with frequency ratio and bivariate logistic regression modelling. environmental, modelling & software 25: 747-759 rakonczai j. – mucsi l. – szatmári j. – kovács f. – csató sz. 2001. a belvizes területek elhatárolásának módszertani lehetőségei. i. földrajzi konferencia, szeged rakonczai j. – csató sz. – mucsi l. – kovács f. – szatmári j. 2003. az 1999. és 2000. évi alföldi belvíz-elöntések kiértékelésének gyakorlati tapasztalatai. vízügyi közlemények 19982001. évi árvízi külön füzetek vol. 4: 317-336 retter, gy. 2006. fuzzy, neurális genetikus, kaotikus rendszerek. budapest: akadémiai kiadó. 425 p sárközy f. 1998. mesterséges neurális hálózatok mint gis függvények. geomatikai közlemények 1: 109-130 tarboton d. g. – bras r. l. – rodriguez–iturbe i. 1991. on the extraction of channel networks from digital elevation data. hydrological processes 5: 81-100 tobak z. – kitka g. – szatmári j. – van leeuwen b. – mucsi l. 2008. kisgépes, kisformátumú (sfap) cir légifelvételek készítése, feldolgozása és alkalmazása környezeti vizsgálatokban. iv. magyar földrajzi konferencia, debrecen zurada j. m. 1992. introduction to artificial neural systems. new york: west publishing company. 683 p droughts, dry spells and low water levels in late medieval hungary (and slavonia) iii: potential dry spells and the drought of (1516-)1517 journal of environmental geography 12 (3–4), 53–67. doi: 10.2478/jengeo-2019-0012 issn 2060-467x droughts, dry spells and low water levels in late medieval hungary (and slavonia) iii: potential dry spells and the drought of (1516-)1517 andrea kiss* institute for hydraulic engineering and water resources management, vienna university of technology, karlsplatz 13, 1040 vienna, austria *corresponding author, e-mail: kiss@hydro.tuwien.ac.at research article, received 10 october 2019, accepted 1 december 2019 abstract as a continuation of the series about droughts in late medieval hungary, we present, analyse and compare further cases, based on contemporary direct and indirect documentary source evidence. the data, concerning (potential) low water-level conditions in 1375, 1378, 1393-1394 and 1517, and the economic problems (and solutions) probably related to multiannual dry (spring, summer?) conditions, recorded in the 1410s and 1420s, are further compared to the recent tree-ring based hydroclimate reconstruction of the owda (old world drought atlas). whereas the cases in 1371, 1375, 1378, (1414-)1417 and 1427-1428 (and before) reflect on localregional problems and also show some conflicts between documentary and tree-ring based reconstructions, in 1393 the local data and the potential danube low water-level evidence mainly reflects on lower precipitation sums in western hungary and the upper-danube catchment. the 1517 case, however, presumably refers to large-scale drought problems in the carpathian basin and beyond. beyond the case studies on individual years or multiannual periods, indirect indicators of drought and dry spells are discussed and main groups of most frequent (potential) indicators defined. preceded by a hard winter, the year of reformation stands out both in documentary and tree-ring evidence as an outstanding drought year, and has particular importance in the paper. keywords: late middle ages, dry spells, low water levels, danube, sava, documentary evidence, owda introduction in the present paper six cases – reflecting on actual dry conditions, and probably, in an indirect way, referring to dry spells that occurred in the carpathian basin – are discussed based on direct and indirect contemporary documentary evidence, and compared to the tree-ring based annually-resolved summer precipitation and springsummer soil moisture reconstruction of the old world drought atlas (hereafter owda; see cook et al., 2015). the sources of the seventh case reflect on a significant or potentially outstanding drought, around (1516-)1517. the discussed indirect cases from 1371, 1375, 1378, (1414-)1417, mid-/late 1420s, and the different groups of potential indirect evidence – related to drought years mentioned in the previous two papers (kiss-nikolic, 2015; kiss, 2017) – are mainly based on reports that may indirectly reflect on drought or prolonged dry conditions. a common characteristic of these indirect watershortage/deficit or dry-spell reports is that all reflect on years when the tree-ring based owda evidence, referring to (spring-)summer hydroclimate conditions, show notably dry conditions or even significant drought. the last case from 1517, with potential, indirect evidence also for 1516, concerns a drought event, where both direct and indirect documentary as well as tree-ring evidence suggest outstanding dry conditions of possibly (or at least) biannual duration. this case is comparable to the greatest drought years of the period between 1450 and 1550, namely to 1473(-1474) and 1540. sources and methods in the present paper in all of the cases legal evidence, charters are utilized, mainly related to different economic (or military) activities, strongly dependent on water supply, and partly to more general, larger-scale problems. consequently, the case studies of the present paper partly refer to drought-related economic problems detected in a relatively small area, in the neighbourhood of a village, while other cases, but especially the one in 1517, discuss severe, possibly countrywide drought problems. thus, the present study differs from the previous ones not only in the proportionally high relevance of indirect evidence, but also because all the (potentially) drought-related information comes entirely from legal-administrative documentation, charters and (official) letters. references on possible dry spells occasionally, ‘randomly’ appear in charters, and can equally reflect on ‘simple’ dry spells or more significant drought events, while even outstanding droughts remained unrecorded. even more indirect evidence is harvest and market-price reports and food-shortage data in years without other destructive extremes (e.g. plague, late frosts, hard/long winters). apart from the legal documentation where, in most cases, only the terminus-post-quem dating of a weatherrelated event, dry spell or drought is known, many of the cases – discussed in the present paper – refer to perambulations, field surveys, where the exact date, the name and location of the landed possession and, within that, 54 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. the approximate locations of the observation are provided. these ‘metadata’ help, almost in all cases, in deciding whether the dry conditions described in the charter could be a general environmental characteristics of the area or there might possibly be a sign of (prolonged) dry conditions. furthermore, the (1516-)1517 drought event was documented in royal correspondence: charters of royal order and an application to the king. concerning geographical locations, all placenames, mentioned in the paper, are presented in fig. 1. with regards to dating, similar to the previous two papers of the series (kiss-nikolić 2015, kiss 2017), the original, julian calendar dating is applied, while the modern, gregorian calendar (hereafter gc) dates are added in brackets. regarding the application possibilities of the treering based owda hydroclimate reconstruction, especially while discussing 14th-century events, further circumstances have to be taken into consideration. as discussed by kiss (2017) in more detail, the tree -ring evidence available from the carpathian basin comes from the north, mainly from the mountain area of present-day slovakia (prokop et al., 2016). however, from the 14th and early 15th century, only a few tree samples are available, and apart from that, the owda reconstruction is based on extrapolated (neighbouri ng areas and europe) data. thus, the reconstruction uncertainties in the 14th and early 15th centuries are significantly higher than in case of, for example, 1517, and this can particularly affect the reconstructed magnitude of extremes. results dry spell or not? mill in very dry place: late summer 1371 on 29 august (gc: 8 sep) 1371 a land estimation and the introduction of the (new) owners to the landed possession in sybolth (zsibót) took place in baranya county in the south-western transdanubia (w-hungary; see fig. 1). the landed possession was located at the “river” alma, the present-day almás-patak (stream), and among the listed cultivated land and immovable properties, a (water)mill with one wheel near to the borders with patafeulde (patafölde) – presumably towards the presentday basal, to the south-west – was mentioned, located at the alma, in a driest place (“in loco siccissimo”). in this description it is rather interesting why a mill would stand in a very dry place. one possible explanation is that the mill was out of use for a longer while, and the stream changed its bed in the meantime, leaving the mill without water. however, alone in itself, this would not explain the “very dry” conditions, and if the mill was out of use, then possibly this condition, significantly lowering the value of the object, would have been mentioned in the charter. another logical, even more likely explanation is that the mill was functioning, but it was a temporary mill, only working in part(s) of the year, when there was much water in the streambed, while in drier periods it stopped working until the next high-water or flood episode started. this would explain no water at the mill, or even the combination of the two explanations, but being the “driest location” emphasised, a most likely option is that in the time of the land survey dry spell or drought prevailed in the area. fig. 1 locations and regions, mentioned in the paper (outside of present-day hungary, modern names are provided while names before 1920 are given in brackets; medieval counties are marked by italics) kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 55 according to the owda, in (spring-)summer 1371 there was drought in western and west-central europe, and in the western part of the carpathian basin were also dry or very dry (fig. 2). similar picture is presented in the documentary evidence available from then neighbouring countries and central europe: the may was very dry in bohemia with frequent fires, but already the winter was quite mild, just like in mainz, where the summer was described as very dry (alexandre, 1987; brázdil and kotyza, 1995). there was great drought in piacenza, florence and the entire toscana, with many “pro pluvia” processions in mid-/late august, and a lightning struck the church spire in posnan (malewicz, 1980; alexandre, 1987). in this year, similarly mild winter and drought were reported in russian sources (klimenko and solomina, 2010). temporary watermill stops working: january 1375 on 8 (gc: 17) january 1375 a land and property survey took place, amongst others, in berench (rétközberencs) along the river tisza, in the great hungarian plain, today in north-eastern hungary (hna dl 96492/1,2; piti, 2010; see also: vajda, 2012). while listing the properties of the village, a watermill was mentioned that operated over a waterflow in times of flooding. however, because of the lack of water, it did not work in the time of the property survey. the survey also affected other landed possessions in the neighbourhood: a dried-up ditch with three weirs is described in the area of monoros (tiszamogyorós), similarly located in the rétköz, the floodplain area of the upper-tisza. the charter also reported on dry mills in the surveyed areas where, instead of water, animals were used for energy supply: one of these dry mills was located in berench. before the mid-/late 19th-century river regulation works, this low lying area along the tisza was prone to floods, and the village was surrounded by wetlands that usually provided high protection against unwanted visitors. examples of significant flood events were also reported in the rétköz area in the mid-/late 14th century, in 1342, 1345 and 1381 (kiss 2019a). the watercourses of this area are under the influence of the river tisza, whose lowest water levels usually occur in mid-/late summer and early autumn, and medium (but not low) water levels are typical in january (lászlóffy, 1982). thus, the report does not necessarily reflect on a drought. nevertheless, as winter high waters/floods were not unusual in this area, and the ditch/watercourse in the neighbourhood, used for fishing, was also dry, we can still state that dry conditions prevailed around and before mid-january in this year. this is also interesting, because just a year earlier, due to exceptionally abundant winter rainfall, the winter-spring of 1374 became famous of great floods in europe (e.g. alexandre 1987; kiss 2019a). winter floods also affected hungary, even if probably the contemporary source referred primarily to the danube area (see kiss, 2019a). regarding the weather conditions of the neighbouring countries, no information is currently available from the winter of 1374 and 1375 in the czech lands, poland, austria, germany and the byzantine empire (malewicz, 1980; rohr, 2007; telelis, 2008; glaser, 2013). however, great drought was reported in liège and mainz in later spring and summer (alexandre, 1987), and droughts were documented in russia in the mid-1370s (klimenko and solomina, 2010). although the differences in climate mechanism make any relationship occasional and somewhat indirect between the two catchments and regions, it is still worth mentioning that low nile floods were reported by byzantine sources in both 1374 and 1375 (telelis, 2008). as our study area is located in the north-eastern part of the great hungarian plain, and in the north-eastern part of the carpathian basin the influence of the hydroclimatic fig. 2 the owda reconstruction for the years 1371 and 1374 (cook et al., 2015; old world drought atlas data on noaa) 56 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. influence of the regions north-east to the carpathian basin are also relevant, it is possible that – similar to the situation in the eastern european plain – overall dry conditions prevailed in the mid-1370s, and also in winter 1475. however, based on the available data, regarding our case study, we can only conclude that a dry spell was observed and described in the rétköz area in january 1475. as for the north-eastern parts of the carpathian basin, both in 1374 and 1375, the owda shows overall somewhat different, drier patterns compared to the rather wet conditions in most of the basin in these two years (see fig. 2). there is also a tendency from wetter (1374) to drier (1375) conditions in these years. moreover, the summer and winter half years could have rather different precipitation and hydroclimatic patterns within the same year. water body dried up due to great drought: spring 1378 the location of the next report is east, north-east from the january 1375 report, in the north-eastern part of the great hungarian plain, between the szamos and the tisza, but nearer to the river szamos, in an area criss crossed by many watercourses, dependent on the water supply of the two main rivers. related to a debate over the ownership of chazlou (császló) landed possession, a perambulation took place on 31 march (gc: 9 april; see fig. 1). during this field survey (nagy et al., 1878), the perambulators also described the properties that belonged to the landed possession, and noted that the local water body dried up in time of great drought, as this water body did not receive water from other water bodies (called “er[d]”), as they found it there (“…., et aqua, que tempore siccitatis magne ex eo, quia deriuaciones ab alys aquis erd dictis ad se faciendas non habent, solent exsiccari, in facie ipsius possessionis reperissent”). although mentioned in general, the text rather describes the (great) drought as a condition what the perambulators experienced during the field survey. before the 19th-century water regulation works, this area was criss-crossed by smaller and larger water channels. the desiccation of a (stagnant) water body, having no direct only indirect connection to the main rivers, still required low groundwater-level conditions in this area, and since groundwater levels are dependent on the waterlevel conditions of the rivers szamos and tisza, the drying up of a stagnant water body indirectly reflects on the low water-level conditions of the two major rivers of the region. for the north-eastern great hungarian plain, and particularly for the region where császló is located near the river szamos, the owda suggests moderate dry conditions for the (spring-)summer period of 1378. nonetheless, in the areas east, north-east to the carpathian basin, especially in the territories of today’s ukraine, the owda suggests a significant drought for this summer (fig. 3). furthermore, in both 1377 and 1379 the owda presents significant droughts (fig. 3; cook et al., 2015). however, the dating of the charter is clear, and also the course of the legal debate makes the 1378 dating unambiguous. as the field survey took place in early/midspring, it is rather possible that still the water-deficit conditions of the previous year continued in this area, and the charter in fact largely also reflect on the problems started at least in 1377. based on documentary evidence from the neighbouring countries and (central) europe, in austria, the czech lands and poland, no information is available regarding 1378, but in (late spring) 1379 there was great drought, the ditches were dry in pomerania (nw-poland); miechów and radomska towns burnt down and there was fig. 3 the owda reconstruction for the years 1377 and 1378 (cook et al., 2015; old world drought atlas data on noaa) kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 57 great (summer) drought in the kingdom of poland (malewicz, 1980). while no weather-related evidence is available from the balkan area regarding 1378, the high level of watercourses was reported in mid-april in the arnhem area (e-netherlands), and in late march the abundance of snow was reported in vicenza, north-eastern italy that stayed for a longer period (alexandre, 1987). beyond that, only the early march great frost at the bodensee is known from the year (alexandre, 1987; glaser, 2013). potential signs of the 1393 drought in medieval hungary in 1393 great drought was described by a number of contemporary sources in central and western europe (e.g. alexandre, 1987; brázdil and kotyza, 1995; rohr, 2007; glaser, 2013). moreover, both based on documentary and the owda evidence, approximately in the same regions of europe as in 1393, the drought continued in 1394 (see fig. 4), while the nile – just like in 1374 and 1375 – also had low flood in this year (telelis, 2008). contemporary charter evidence may also provide indirect parallels in the carpathian basin to this great drought event, even if the treering based hydroclimate reconstruction of the owda only suggested drought in the western, north-western and the most north-easterly parts of the carpathian basin for this year. no direct contemporary reference is available in medieval hungary that would mention this drought. however, some indirect evidence may increase the chance that this drought affected larger areas in (western?) hungary, too. an early harvest reference is available from march 1394, dating the illegal harvesting of grapevine prior to 8 (gc: 17) september 1393 in kál, north to lake balaton, in the central transdanubia (hna df 200361; kiss, 2016). although this is primarily a temperature-related information, great droughts are usually accompanied by higher temperature values and earlier harvests (see e.g. wetter et al., 2014; kiss, 2018; camenisch et al., 2019). in november 1393, a court hearing took place: the abbot of the monastery of elefánt (lefantovce-sk) blamed the noble neighbours for causing water deficit to the watermills of the monastery with diverting the course of the mill canal of the river nitra (hna dl, 7902; mályusz, 1951). although the abbot presented as a fact that the water was diverted, as no further part of the legal debate is known, it is not possible to decide whether the abbot was right in blaming the neighbour, and in what extent the neighbour can be blamed for the water deficit. however, in another case, in 1422, when the abbot blamed neighbouring landowners with causing destruction in the mill of the monastery, the damage was caused by the vehement flux of the river and not by human intervention (see kiss, 2019a). a further case concerns the danube in 1393: similarly in november, a charter was issued containing the complains of the parish priest of pispuky (püspöki; today in bratislava-sk), referring to an island that changed location due to previous floods. situated closer to orozwar (oroszvár; today part of bratislava-sk), the serfs of the latter domain started exploiting (illegally) the forest on the island (hna df, 237891; mályusz, 1951; see also kiss, 2019a). as usually it was easier to exploit island forests and especially to transport the wood from the island areas, in times of low water levels, it is possible that the water level of the danube was low for a longer period in this year, providing suitable conditions for the illegal woodcutters. this is especially likely, as there was great drought in austria in 1393 (rohr, 2007). on 28 june (gc: 7 july) 1394 a perambulation took place in baranya county, in the area of today’s majs, (nagy)nyárád and kölked, between the lands of the local landlord, lászló töttös and the cardinal-bishop of pécs. during the field survey and perambulation between laak, laymer, kerekyghaz and maysa landed possessions, the survey proceeded from lak towards the west, along the fig. 4 the owda reconstruction for the years 1393 and 1394 (cook et al., 2015; old world drought atlas data on noaa) 58 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. big (main course of the) danube, reached the place where the small danube (a danube branch) left the big danube; here, just along the river and its branch, the charter described a dry meadow (nagy, 1878). taking into consideration the moderate elevation differences and low elevation conditions of the area, the mentioning of a dry meadow right along the main danube and its branch is rather interesting, as the area is under the direct hydrological influence of the danube. it is also interesting that in 1395 an italian delegate – staying in buda and sending regular reports on his ’observations’ in the royal court, the town and the country – asked his lord, the duke of mantua, for permission to return to italy, because his spendings were too high, caused by the current high prices in the town (óváry, 1890; see also: kiss et al., 2016). although little is known about the weather conditions and harvest results in 1394, the high prices on 27 november (gc: 6 december) 1395 might be still related to the great drought, especially because, according to the owda, there was also significant drought in 1394 in large parts of western, central and even in eastern europe, but drought continued in the german areas, eastern europe, and also in transylvania and the balkan in 1395 (cook et al., 2015). however, the owda does not list most of the carpathian basin among the affected areas. based on the owda, however, the (spring-)summer drought in 1394 only affected transylvania and the north, north-eastern (hilly) areas of the carpathian basin. although the reconstruction also suggests conditions somewhat drier than usual in the western part of the country, including the little hungarian plain (kisalföld), which was the main crop supplier of buda in the late middle ages (kubinyi, 1975), this general water deficit does not reach the extent of a drought in the owda reconstruction (see fig. 4). nevertheless, if this moderate dry (spring-)summer arrived after a much drier year, theoretically the somewhat better conditions (and harvest results) could be still insufficient to provide enough foodcrops to feed the entire town and its agglomeration. in conclusion, a number of indirect evidence suggest that the 1393, and possibly also the 1394, european droughts had some impacts in hungary, too. the indirect evidence, on the one hand, refers to the contemporary pontentially low water-level conditions of the danube, reflecting on the great (hydrological) drought that affected the german areas and austria in 1393. on the other hand, all other – potentially drought-related – information comes from the western, north-western part of the carpathian basin, where otherwise the owda also suggests a (moderate) drought for this year. it is not clear whether the high prices, mentioned by an italian delegate in 1395, are still related to this drought, however, except for most of the mediterranean, 1394 was also a drought year in most parts of europe. 1415-1416: problematic years – full of contradictions? in connection with a postponed legal debate in 1415, very high prices or dearth of the recent past, that had already passed, were mentioned on 30 july (gc: 8 august) in doboka county, transylvania (hna dl 73953; mályusz, 1997, see also fig. 1). as the information comes from around harvest time, most probably the bad harvest of the previous year or years was followed in 1415 by a better one, so that the crisis was over with the new harvest. dated to 6 june (gc: 15 june) in the same year, a royal order (of king sigismund) was issued in support of the parish priest of szentpéter (today part of cluj-napocaro), related to a mill whose utilities belonged to the parish, but the neighbouring kolozsvár (cluj-napoca-ro) town questioned this right (jakab, 1870). there is a rather interesting sentence in this charter, stating that the serfs of the parish, in their grave poverty – as heaven took away their resources –, could not afford a coach to carry their crop harvest to the mill, and therefore for them this mill was of highest importance, as they would have been unable to travel to another, distant mill. this sentence – possibly reflecting on multiannual problems – might be particularly interesting, when we take into consideration that the parish was located in one of the richer, central parts of transylvania. however, the situation probably becomes more understandable when taking into consideration the previous evidence on great dearth, also coming from transylvania. similar problems were recorded in the next year: on 6 october 1416, queen barbara/borbála (wife of king sigismund) ordered sopron county officials to prohibit the export of cereals (házi, 1923). the prohibition of cereal export had been previously decided, because the king wanted to avoid the further increase of the countrywide high prices/dearth (”caristia non modicum”), indirectly suggesting larger-scale problems within the country. hardly more than a month before, on 3 (gc: 12) september 1416, a high officer of the austrian prince sent an official letter to the town council of sopron asking for the reason of prohibiting the export of oat to austria (házi, 1923). as vienna in the late 15th century largely depended on grain import from the czech areas and hungary, the prohibition most probably caused shortage in resources. moreover, the document indirectly also suggests that the royal order for prohibiting cereal export was most probably dated not much earlier, perhaps to (late?) summer, possibly responding on an overall weak harvest, and a (reasonable) fear of a(n even graver) dearth in hungary. however, it is interesting that, despite the intensive daily trade connection, the austrian court had no knowledge of the reasons of prohibition in hungary. this circumstance may indirectly suggest that in the sopron area and at the western borders of the country there was no bad harvest or significant shortage of cereals (oats in specific) in this year. the reports on very high prices and/or great dearth in transylvania in 1415 and then in the entire country in 1416 altogether suggest significant problems with harvests on a multiannual scale in 1415, 1416 and most probably also, at least, in 1414. as large-scale (crop) harvest problems in the country are usually the consequence of prolonged dry conditions, and sometimes also of extreme hard winter, late frosts or, even more rarely, the too much precipitation, it is rather important in finding possible explanations that, based on the owda, drier than usual conditions prevailed in 1414 and 1415, while 1416 was dry in the north-west, but in the rest of the country average or slightly wetter conditions were dominant (see fig. 5). kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 59 thus, the owda does not suggest for the carpathian basin strong drought for 1414, 1415, and in 1416 only the western, north-western part of the carpathian basin was dry, while the rest of the country was more wet than dry. around average or moderately wet conditions, in themselves, are usually favourable for agriculture in the central and eastern parts of the country; apart from the temperature extremes, only very/prolonged dry and rarely prolonged very wet conditions cause problems. furthermore, a mid-july danube flood and a winter flood in the north-east, in the upper-tisza catchment was recorded in january 1416, whereas practically no ongoing floods of carpathian basin origin were documented in 1414-1415 (see kiss, 2019a). the situation what we gain from the documentary evidence of the neighbouring countries is even more complex, partly also contradictory. in poland, for example, documentary evidence suggests rains in summer 1414, and the whole year was rather wet in 1415 (malewicz, 1980), while for both (spring-)summers the owda suggests notable dry conditions (fig. 5). rainy summer was suggested for 1415 in bohemia (brázdil and kotyza, 1995) – the owda suggests considerable dry conditions for the same period (fig. 5). in austria, summer was rather warm in 1414, but 1415 was most probably also wet (alexandre, 1987). the picture is similarly contradictory in other parts of western and (central) europe. based on glaser (2013), in the german areas, after the hot and dry summer of 1414 and fig. 5 the owda reconstruction for the years 1414-1417 (cook et al., 2015; old world drought atlas data on noaa) 60 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. the presumably average summer, no information is available regarding summers (or other seasons) until 1418. alexandre (1987) suggests that, after the summer droughts in 14121414, spring-summer of 1415 was wet with inundations, floods were also reported in june-early/mid-july in 1416 in the westernmost parts of the german and the eastern parts of french territories. these descriptions clearly contradict with the owda reconstruction (see fig. 5), where notable drought is presented in the same areas. (northern) poland was similarly wet in summer 1414 and in 1415 (malewicz, 1980) – but, at least, in case of poland the owda also suggests wetter conditions. on the other hand, in 1416 great heat and drought was described between mid-august and early october in forli and sienna, in italy. usually collected in (late june)-july, such a late-summer drought would not have affected the crop harvest in hungary. thus, 1414 might have been problematic because of dry and hot weather, while in case of 1415 documentary evidence suggest wet, while the owda suggests dry conditions for (spring) summer 1415 and 1416 (see fig. 5). winters were average, cold in some parts in bohemia and the german areas (brázdil and kotyza, 1995; glaser, 2013). in general, the 1415-1416 cases provide a rather contradictory picture. the 1415 transylvanian reports, well before harvest time, mainly refers to problems of the previous years, especially to the dry period of 1412-1414. in 1415 and 1516, the shortage of crops inducing export prohibition might have been partly or mostly due to extraordinary wet conditions in the central and eastern parts of the carpathian basin. this might be also supported by an application from the western edges of szatmár county, generally complaining on the many floods (of the preceding times), caused by the abundant multiplication of rains prior to 1417 (see kiss 2019a). however, considering the rather contradictory, opposite patterns – presented by documentary and the owda reconstruction – we cannot completely exclude the possibility that also in 1415 and 1416 dry (and or cold) conditions prevailed in the first, most important spring part of the vegetation period in the central and eastern parts of the country that badly affected harvests in these years. 1417: drought or not? the charter of the st. stephan order in székesfehérvár, issued on 25 december 1417 (gc: 4 january 1418), states that their zedregh landed possession often lacks water in summer (“ceterum quia tempore estiuali sepius aqua in ipsa possessione deficeret”), and when it happens, the other owner is obliged to provide ample water supply to the other landowner, his serfs and animals (hna dl 105344; see also mályusz and borsa, 1999). according to fejér (1844b), the landed possession, with settlement, was located in the southern part of fejér county, between the river sárvíz/sió and the danube, in the area what is today előszállás, alsószentiván and nagykarácsony (see fig. 1). the landed possession was located in a sandy wetland area, and was clearly populated at the time of the charter issue, and at least one notable local noble family also lived there. moreover, another charter of the same survey is available from the (same) december 1417 survey (hna dl 43377) – yet without mentioning the water deficit problem. as the charter specifically states the summer water deficit problem, and therefore the problems has great importance for the landed possession, it is rather possible that the summer water deficit mention reflects on current (or near-past and/or multiannual) problems. the owda suggests significant drought for western and central europe for (spring-)summer 1417. with particular intensity in the north-west, based on the owda, in 1417 there was also drought in the carpathian basin. moreover, based merely on the owda, in the western part of the country dry or rather dry (spring-) conditions prevailed in each summer already from 1407 (see fig. 5). as for the documentary evidence in other parts of central europe, the winter of 1417 was memorably hard and rich in snow: both austrian, czech and german sources speak about the severity of this winter. in general, from liguria through germany to poland, the very cold (and snowy) character of the winter was emphasised in 1417 (malewicz, 1980; alexandre, 1987; brázdil and kotyza, 1995; glaser, 2013). in poland the winter was so cold that crops were destroyed, and – as summer was also unfavourable for crop development – there was bad cereal harvest (malewicz, 1980). although the source does not describe summer conditions any further, one possibility for the cause of bad harvest might be (spring-)summer drought. no information on this summer is available from the czech lands regarding the year 1417 (brázdil and kotyza, 1995). in austria, the cold and snowy winter, when the danube also got frozen, was followed by good vintage and good quality of wine that suggests warmer than average summer conditions (alexandre, 1987). moreover, good harvest may also suggest that, despite the hardness of winter, the winter frost did not severely damage the vinestocks (or the snowcover was thick enough). famine in mid-/late 1420s: any relationship to drought? on 19 october 1428, king sigismund gave some tax relief and further privileges to the iasonians, because of the dearth or famine affecting them for years (propter caristiam sive famem aliquorum annorum, post sese continuo praeteritorum; see fejér 1844a). documented in midfebruary 1428, most probably in the previous year the town of nagyszőlős (vynohradiv-ua) in ugocsa county, in the north-east, partly burnt down (hna dl 70845, see fig. 1). in the middle ages, iasonians lived in one block in iasonia, mainly around the present-day jászberény and jászfényszaru towns, but also lived scattered in various regions, partly east, south-east to pest (e.g. cinkota; today part of budapest), and partly along the river tisza in the great hungarian plain. although, similar to cumans, their main activity was animal husbandry, they were traditionally more involved (than cumans) in land cultivation, too. the multiannual famine among the iasonians clearly had to be, at least partly, related to unfavourable weather conditions, a circumstance that hit their traditional economy for a longer period of time. thus, it was most probably not (only) the result of a single hard winter, late frost or any other, individual extreme event. furthermore, as iasonians mainly lived in the floodplains of the drought-sensitive great hungarian plain, their agricultural activities strongly depended on the availability of water. kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 61 the fire incident in nagyszőlős (today vynohradiv in the transcarpathian region of ukraine) occurred in an unknown time, but not immediately before mid-february (i.e. more probably in 1427), and not the entire town but only part of it burnt down. as large scale fire events favour dry and windy conditions, in such a case there is a higher likelihood that prolonged dry and windy conditions were also responsible for the calamity. however, we have to add that chances for devastating incidental fires are also higher in hard winters and prolonged hot (and windy) conditions. thus, drought is not necessarily a precondition. although rather indirectly, it might be also important that, after the autumn 1424 river nitra flood, no ongoing floods of carpathian basin origin are known from contemporary documentation until 1432 (see kiss 2019a). naturally, the lack of flood-related documents does not mean the complete lack of considerable or even great flood in a year. nevertheless, when less unusual floods occur for multiple years then there is more chance that floods remain unreported, and in case of a longer period without flood evidence the likelihood for generally drier conditions is higher (but not exclusively) than in other periods. for 1427 and the years before, the owda suggests dry or very dry conditions. in fact, rather dry conditions prevailed in each year from 1417 until 1427; based on the owda, the first wetter year was 1428 (see fig. 6). thus, it is rather possible that the prolonged dry conditions (11 years!) had major responsibility in the multiannual food shortage problems described in the charters. moreover, based on a royal charter, the winter of 1427 was rather (or even: exceptionally?) cold and snowy in transylvania, when turkish troops broke into the country and caused immense damages (fejér, 1844a). combined with the multiannual drought, hard winter conditions might have meant an additional stress and could increase the food supply problems. the ‘perfect match’ in the year of reformation: the great drought of (1516-)1517 based on the owda hydroclimate reconstruction, in the year of the reformation (luther’s proclamation to the bishop of mainz: 31 october, 1517), an outstanding drought occurred in (spring-)summer all over central and western europe, and already 1516 was a drought year in europe (see fig. 7). this reconstruction is in ‘perfect match’ with the information derived from documentary sources: both in direct and indirect evidence, this drought was also documented in contemporary sources in the carpathian basin. in a royal order written on 19 (gc: 29) august 1517, the king ordered all judges, lay or ecclesiastical, first to suspend for 15 days and then to completely stop all legal procedures in the kingdoms of the hungarian crown in which the duke of slavonia, ferenc hédervári, and his vassals (so-called “familiares”) were involved, as they were at that time occupied by the defence against a threatening turkish attack in the two most endangered counties, valkó (vuka-hr) and pozsega (požega-hr), in hungary and slavonia (hna dl 91054; see also fig. 1). the fact that the two counties, located along the lower sections of the river sava, were most in danger reflects on the one hand the location of the turkish strongholds, but also suggests prolonged critical water shortage in the entire catchment area of the river, not only in the south-eastern part of the alps and slavonia, but also in bosnia. as a potential parallel, extreme low sava water level was mentioned in 1474: at that time it was related to an outstanding great drought, affecting the carpathian basin and the south-eastern alpine area, both in 1473 and 1474 (kiss and nikolić, 2015; kiss, 2017). the similarities in conditions may raise the possibility that the drought probably started already in 1516. fig. 6 the owda reconstruction for the years 1427 and 1428 (cook et al., 2015; old world drought atlas data on noaa) 62 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. another report, indirectly reflecting on drought and unfavourable weather conditions, also suggests that significant anomalies occurred in 1517 and possibly also in early 1518. on 17 (gc: 27) april 1518, a letter was sent by the town officials of nürnberg to the nearby rosenburg, providing an explanation on the current high prices of meat in the german areas. according to the letter, the problem originated in hungary: lacking fodder in winter, large part of the cattle perished that caused a shortage of meet in the german areas (thallóczy, 1900). mass loss of cattle in hungary was usually related to bad hay harvest, which was predominantly the consequence of drought. however, fodder shortage – resulting mainly the loss of young animals – might have also developed during prolonged hard winters. a multiannual drought, alone in itself, or the combination of a drought and then long hard winter could have catastrophic consequences on the cattle population. a further, indirect evidence also suggests considerable problems: on 30 may 1517, the lead tax officer sent a report to the duke of slavonia and croatia, stating that it was not possible to gather taxes from his slavonian serfs due to their extreme poverty that was so great that many died in famine (iványi, 1942; see also kiss, 2019b). apart from the drought both in 1516 and 1517, winters of both years were, at least partly, also severe. nevertheless, the selling and production prices, recorded in the tokaj-hegyalja wine region (in tállya; see gecsényi, 1966), were relatively low and decreasing in both years, indirectly suggesting that the winters of these two years were not hard enough to have multiannual negative impacts on the vinestocks and wine production. already the summer and autumn of 1516 was very dry, but after a hard and moist winter, the spring of 1517 was again unusually warm, and extreme dry – the driest of the century in the german areas. heavy frost that caused great damage in the cultivated vege tation was followed by very hot and dry summer, also reflected in bad hay harvest results. however, the second decade of july brought rain and, according to glaser (2013), rainy weather continued in august and much of september in the german areas. the winter of 1518 was suggested to be altogether normal, but with great regional differences (glaser, 2013). the very hot and dry character of summer 1516 is also emphasised in bohemian sources, and in fact – just like in poland – the entire year was dry with low water levels of the river elbe (brázdil et al., 2013). discussion (1516-)1517: comparable to the most severe droughts of 1473(-1474) and 1540? in france, le roy ladurie (2004) referred to the 1517 drought as comparable, or even more severe, than the one in 1473, also legendary in hungary (see kiss and nikolić, 2015; kiss, 2017). for the carpathian basin, the owda suggests lower pdsi index values for 1517 than for 1473 or even for the other outstanding drought, 1540 (see fig. 8). based on the information available in documentary evidence, it is difficult to decide over the differences in the magnitude of the drought events – all three were important, but for 1473-1474 and 1516-1517 we have more direct contemporary evidence that refer to outstanding drought. in hungary, we have no information about broad-scale food or fodder supply crisis in 1473-1474, but both in 1516-1517 and after 1540 there were significant problems documented. both in 1474 and 1517 low water-level problems were recorded. however, only in one case, in 1517 mass perdition of cattle was reported. based on this latter information, fig. 7 the owda reconstruction for the years 1516 and 1517 (cook et al., 2015; old world drought atlas data on noaa) kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 63 probably the (1516-)1517 drought holds the most signs of an outstanding drought – this drought was also singled out as most extreme between 1450 and 1550. however, the evaluation strongly depends also on source availability. another, rather thought-provoking circumstance is the potential relationship between the great drought of 1517 and the previous years and the start of the reformation. even if the reasons for the reformation rooted in societal problems and the (moral, structural) crisis of the church, the increasing societal and economic tension within the society, caused by bad harvests due to unfavourable weather conditions, and the recurrent significant and outstanding droughts in particular, provided a favourable background to the increasing desire in the lower layers of society for considerable changes. in the earlier part of the decade (i.e. 1513-1514) this increased societal tension manifested itself in peasant revolts that affected much of central europe including austria, german territories in the south, south-west as well as the hungarian kingdom (see kiss 2019b). thus, even if no direct relationship can be detected between multiannual dry conditions, droughts, societal tension and abrupt changes, multiannual dry conditions were partly or mainly responsible for repeated bad harvests that could be an important contributing factor, a catalyst of societal changes. no such substantial, abrupt changes can be detected in the 1470s and around 1540, which fact also reflects on the primary importance of (long-term) socio-economic processes over the importance and influence of multiannual unfavourable weather conditions. potential, indirect references on droughts or dry spells several types of potential, indirect indicators of dry spells or drought were already listed in this and the previous papers of the series. in this subchapter a short overview of these indicators, and some additional further indicators are discussed in brief. it is important to note that most of the listed cases or problem groups did not only occur during dry spells or droughts; however, we argue that the frequency of these problems – and therefore the likelihood for documentation – is often, but not necessarily, higher than in other years. the list presented here is not exclusive – further indirect indicators may be suggested later, in due course. potential signs of large-scale harvest problems – often induced by prolonged dry spells or drought – could be, for example, the increased number of controversies, violence, illegal gathering or confiscation (robbery) of hay or crop harvest and the similarly illegal (crop) cultivation of other people’s meadows. more hay-related problems such as robbery, violence against harvesting peasants or land-usurpation were documented in charters, for example, in 1473, 1479-1480, 1494, 1503, 1506-1507, the early 1510s or in the late 1510s and early/mid-1520s. based on the abstract search in the charter abstracts of the medieval collection of the hungarian national archives, for the period 1300-1526, currently we found 107 years when hay-related problems, negotiations, illegal acts (violent attacks, illegal activity, meadow occupation etc.) were mentioned in legal documentation at least once a year (sources: hungaricana database). out of these 107 years, the owda suggested drought or severe drought in case of 44 years, while notable dry conditions, dry spells were in 21 years. in case of other 40 years no significant dry conditions were presented by the owda, and only in two cases hay-related controversy was mentioned in particularly wet years. thus, this means that in 2/3 of the hay-problem cases notable dry conditions or droughts were captured by the owda for the (spring-)summer period. however, it is important to emphasise that the relationship between dry conditions and hay-related controversies is far not exclusive: sometimes even in particularly wet years we can meet with such problems. still, there is a higher likelihood for the occurrence of such problems in dry years. fig. 8 the owda reconstruction for the years 1516 and 1517 (cook et al., 2015; tree ring drought atlas portal) 64 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. rather similar results can be gathered from the same late-medieval database regarding crop-related controversies, violence and the illegal gathering of crop harvest. based on the owda, out of the documented 56 years, the (spring-)summer period of 20 cases were very dry, 15 were notably dry, 17 were – on the carpathian basin level – average, and four were wet. thus, around 2/3 of the cases were related to dry or very dry conditions. nevertheless, the negative influence of other weather extremes (e.g. hard winter, late frosts) as well as the impact of socio-economic processes also has to be considered, and these provide a significant bias while studying the relationship between dry conditions and harvest results. moreover, there were also changes within the late medieval period that has to be considered: for example, the increase in documentation and the quantity of the available legal evidence (see e.g. kiss 2019a), the growing population and export possibilities (e.g. grain) or the increasing cattle export and the need for fodder (i.e. increased importance of haylands). a small group of cases can be related to controversies and purchasing danube islands: as we could see before, in 1393-1394 the water level of the danube was most probably quite low. other interesting cases are related to island purchases: these cases lead us back to the late 13thearly 14th century. danube islands were sold in 1262 and before early 1305, most probably in 1304 (kiss, 2019a): according to both the owda and documentary evidence (see e.g. rohr, 2007; glaser, 2013), both years were particularly dry not only in the carpathian basin, but also in western and west-central europe. moreover, extreme low water-level conditions of the danube were directly reported in lower austria in 1304 that fits rather well to potential low water level conditions of the danube that made island areas (temporarily) larger, and increased the chances of the owner to sell the island for a better price. a further group of frequently-documented events that had a higher likelihood of occurrence in dry (and windy) periods is fires. although (unintentional) fires can also occur during hard winters and/or other cold and windy periods, and therefore reported major fire events cannot be automatically connected to a dry spell or drought, fire outbreaks have more chance to become particularly extensive and destructive under dry and/or windy than wet conditions. moreover, during hot (and dry) periods the likelihood for the occurrence of convective events with thunders and lightning – often responsible for the start of major fire events – is also much higher (e.g. 1506: eger; see kiss, 2017). significant years with many fires were, for example, reported in 1473; but charters also refer to fires in a number of cases in the 14th, 15th and early 16th centuries. for example, fires were reported prior to 1305, may 1314, in 1317, before 1324, in 1332, 1354 and 1400 – in these years dry or very dry conditions were reconstructed by the owda (cook et al., 2015). however, other years with known major fire events, for example 1338, 1342, 1350, 1351 or 1356, were not marked as dry in the owda catalogue (data: kiss, 2016). nevertheless, as most of the fires can be only dated prior to its mention to an unknown time, this dating uncertainty may limit the possibilities for a more accurate comparison. more clear relationships between dry conditions and fires were documented in the late 15thearly 16th centuries when almost all reported great fires occurred in years when dry or very dry conditions were suggested by the owda. for example, dry or very dry (spring-)summer periods coincided with the years with major town/settlement fires in 1482, 1489, 1500, 1506, 1512, 1515, 1518 or 1525; even if, for example, the town fires of 1518 and 1524 mostly do not ‘fit’ this series with its average or wetter conditions (data: kiss, 2019b). another important group of indirect indicators in the late-medieval period is the major local-regional ottoman turkish raids (not the military campaigns of the emperor) in hungary and slavonia. prolonged dry periods with low water levels of major rivers, dry summer-early autumn periods and/or hard winters with steady frosts (with or without snow) and firmly frozen rivers greatly increased the likelihood of swift turkish raids. thus, even if, similar to fires, this indicator does not necessarily refer to dry conditions, dry conditions – just like in the 1517 case – made favourable conditions for the turkish troops nearby the country borders for a devastating attack in (northern) slavonia or southern hungary. years with swift devastating turkish attacks, also mentioned in documentary evidence as dry were, for example, 1473, 1474 and 1479. moreover, the owda suggests notably dry conditions or even drought in other years with known major turkish raids, for example, in 1418 (see bánlaky, 1928; cook et al., 2015). food shortages and the mention of dearth or famine – as well as prolonged problems among traditionally pastoral communities – generally refer back to (multiannual) harvest problems, often, but not exclusively induced by drought. as for the pastoral communities, the problems of the morlachs in dalmatia were mentioned in relation with the great drought in the early 1360s and the grave poverty of cumans and iasonians in the early/mid-1470s and 1410s (see kiss and nikolić, 2015; kiss 2017, and the present paper). some of the reported significant food shortages such as, for example, 1312 (kiss et al., 2016), coincided with very dry conditions in the owda for 1312 and also with central european documentary evidence for 1311 and 1312 (rohr, 2007; cook et al., 2015; kiss et al., 2016). another case that refers to countrywide problems is 1381: in this year there was significant dearth (see kiss et al., 2016). as there was also plague epidemic in the country, dearth might be also due to that; however, as based on the owda this year was very dry in the carpathian basin, another possibility is that, due to drought, the harvest was bad in this year. a further, thoughtprovoking example is the report from csicser (čičarovce-sk; see fig. 1) in the north-eastern part of the great hungarian plain about the grave poverty, starvation and even death of serfs in 1500; another year suggested as rather dry by the owda (cook et al., 2015). as we could see it on the example of 1517, apart from food shortages, large-scale shortage or lack of animal fodder could as well have disastrous consequences, in the form of mass loss of animals – especially when a hard winter followed the bad hay harvest caused by drought. on a local scale, probably similar problems were recorded in temes county in may 1511, when during the hard winter of 1511 a significant shortage or lack of hay developed, and some serfs and landowners started illegally or even forcedly take their neighbours fodder (hna dl 37883). as both (spring)summer periods of 1509 and 1510 were rather dry according kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 65 to the owda, apart from the hard winter in central europe (see e.g. brázdil et al., 2013; glaser, 2013) that could be – even alone, in itself – responsible for the critical shortage of hay, previous weak hay harvest results, caused by drought, might have also been a contributing factor to the considerable shortage of fodder. during prolonged food-supply problems there is a higher likelihood of social unrest as happened, for example, during the climatic anomaly of the early spörer solar activity minimum (see camenisch et al., 2016). it is also interesting that the great peasant revolt of 1514 (started in transylvania already in 1513) was, according to the owda (cook et al., 2015) and also to central european documentary evidence for 1513 and 1514 (e.g. rohr, 2007; glaser, 2013; brázdil et al., 2013), preceded by a rather severe multiannual (spring-)summer drought period (see also kiss, 2019b). additionally, sometimes there are also interesting coincidences that might not have a key influence on the flow of events but probably still had some additional negative effects that made a crisis situation even graver. although we found no direct mention of a drought in documentary evidence, an interesting example is the case of trau/trogir in 1420. as part of the (multiannual) dalmatian war, in this year the town was besieged and cut off from all supply (see e.g. bánlaky, 1928), which caused great famine and lack of water in the town, and finally forced town citizens to give up resistance and accept venice as their natural lord (fejér, 1844a). coincidently, based on the owda, the dalmatian coastline and trogir in specific had to endure drought in these years. in fact, the drought was the most severe in 1420 (cook et al., 2015), which circumstance might have made water (and food) supply for dalmatian towns, and also for trogir, even more difficult than in average or wet periods. the year 1420 was outstanding warm in west and central europe also based on documentary evidence (see e.g. brázdil and kotyza, 1995). hunger in extensive areas of dalmatia was similarly recorded in 1413, referring to 1412 (mályusz, 1994) – based on the owda a year with rather dry conditions in the croatian kingdoms (including dalmatia) and most of hungary. however, similar to 1420, war with venice (and potentially also pestilence) might also have negative impacts in these areas, though in this year the lands of dalmatia were less directly affected by the war than in 1420 (bánlaky, 1928). even further back in time, a potentially similar case was recorded in 1304, when great poverty was described in “slavonia” (referring to any of the croatian kingdoms) – one of the reasons of these grave problems might be political uncertainties (kiss, 2016). nonetheless, as suggested by the owda and also documentary evidence from other parts of central and western europe (e.g. alexandre, 1987; brázdil and kotyza, 1995) a possible reason could also be prolonged drought. another, rather indirect and uncertain but still thought-provoking case, this time in hungary, is 1525. according to the sperfogel chronicle, after many years of regular tax increase and the repeated devaluation of the currency, with reference to the (otherwise real) danger of a major turkish attack, in 1525 the king decided to apply again the dangerous tool of money devaluation, which led the country into great price increase and the lack of even basic goods purchased abroad (wagner, 1774). and although no any mention of a drought is known from contemporary evidence, based on the owda there was significant drought in 1525 that could increase the negative consequences of the money devaluation and the possibly multiannual impacts of plague epidemics, hitting the country in 1522-1524 (see kiss, 2019b). as we could see in the present paper on the example of the 1370s, in certain cases the conditions of watermills, ditches (stagnant water bodies, fishponds/fisheries, meadows) might be applied as indirect indicators of a dry spell. additionally, further potential, indirect indicators might be worth to test in future. in england, for example, even the mention of dried up trees in contemporary administrative sources in certain years might be an indicator of drought (see e.g. pribyl, 2017). owda droughts – with no documentary evidence? although regarding many of the years, highlighted by the tree-ring based owda hydroclimate reconstruction, at least indirect evidence is available, some markedly great drought years in the owda reconstruction up to now has no any connected, direct or indirect, late medieval documentation in the carpathian basin. based on the owda, in the carpathian basin the cumulative (extrapolated) pdsi values were under (or around) -1 in 1300, 1303, 1306, 1311, 1314, (1317), 1320, 1322-1324, 1326, (1328), 1334, 1335, 1354, 1355, 1357, 1358, 1365, (1367), 1377, 1381, 1385 and 1403-1406, 1412, 1417, 1419, 1422, 1423, 1427, 1431, 1433, 1443, 1444, 1500, 1503, 1506, 1507, 1513, 1514, 1518 in late medieval times. this value was (around or) under -2 in (1312), (1323), 1325, 1332, 1360, (1362), 1384, 1420, 1421, 1426, 1439, 1440, 1473, 1479, 1480, 1483, 1484, 1504, 1512, 1516, 1519, (1520), 1525. in two cases, in 1333 and 1517, the pdsi value was under -3, and in one case in late medieval times this index value was under -5, in 1361 (data: tree ring drought atlas portal). however, we have to add that these values refer to the entire carpathian basin, and within this large region, there could be great regional differences in drought intensity within the same year. for example, in case of a great drought in the eastern and central parts of the carpathian basin, it was rather possible that the drought did not affect the western parts of the basin, and in this case the average pdsi index might not show any extreme on the level of the entire carpathian basin, even if clearly there was a significant drought in that year. a potential example for such a case is 1507 (see kiss, 2019c). out of the years with under -3 pdsi values, we have not yet found any documentary-based reference for 1333, but sources do refer to 1361 and 1517 (kiss, 2017; and in the present paper). direct or indirect evidence is also available for the years with pdsi values under -2, in 1360, 1362, 1420, 1426, 1439-1440, 1473, 1479-1480, and probably for 1483 and 1504, but some kind of (even if very indirect) information can as well be connected to most of the years with pdsi values under -1 (see examples in the present paper), even if the causal relationship in most cases cannot be proved with certainty. 66 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. conclusions in the present paper potential dry spells, mainly available in indirect evidence, as well as uncertain and contradictory cases are discussed and compared to the tree-ring based (spring-)summer hydroclimate reconstruction of the owda. direct and indirect evidence refers to dry spells or even a potential drought in the 1370s, while a contradictory, mixed dry and probably very rainy and then again dry periods are discussed in the 1410s, and a potential multiannual dry spell or drought in the 1420s. rather clearly drought-related information comes from the year of the reformation, 1517, with indirect reference to 1516. furthermore, groups of (potential) indirect evidence, presented in medieval legal-administrative (mainly charter) documentation were defined. the presence and more frequent occurrence of problem groups in certain years or periods may help us to identify more dry spells or droughts without direct reference in contemporary documentation. references alexandre, p. 1987. le climat en europe au moyen âge. contribution à l’histoire des variations climatiques de 1000 à 1425, d’après les sources narratives de l’europe occidentale. éditions de l’école des hautes études en sciences sociales, paris, 505, 514, 517, 563–566, 592–593. bánlaky, j. 1928. a magyar nemzet hadtörténelme. vol. 9. grill károly, budapest. brázdil, r. and kotyza, o. 1995. history of weather and climate in the czech lands i (period 1000-1500). zürcher geographische schriften 62, zürich, 110–111, 117, 121–125, 169. brázdil, r., kotyza, o., dobrovolný, p., řezničková, l., valášek, h. 2013. climate of the sixteenth century in the czech lands. masaryk university, brno, 77–78. camenisch, ch., keller, k.m., salvisberg, m., amann, b., bauch, m., blumer, s., brázdil, r., brönnimann, s., büntgen, u., campbell, b.m.s., fernández-donado, l., fleitmann, d., glaser, r., gonzález-rouco, f., grosjean, m., hoffmann, r.c., huhtamaa, h., joos, f., kiss, a., kotyza, o., lehner, f., luterbacher, j., maughan, n., neukom, r., novy, t., pribyl, k., raible, c.c., riemann, d., schuh, m., slavin, p., werner, j.p., wetter, o. 2016. the 1430s: a cold period of extraordinary internal climate variability during the early spörer minimum wit social and economic impacts in north-western and central europe. climate of the past 12, 2107–2126. doi: 10.5194/cp-12-2107-2016 camenisch, c., brázdil, r., kiss, a., pfister, c., wetter, o., rohr, c., contino, a., retsö, d. 2019 extreme heat and droughts of 1473 and their impacts in europe in context of the early 1470s. accepted: regional environmental change (2019). cook, e.r., seager, r., kushnir, y., briffa, k.r., büntgen, u., frank, d., krusic, p.j., tegel, w., van der schrier, g., andreu-hayles, l., baillie, m., baittinger, c., bleicher, n., bonde, n., brown, d., carrer, m., cooper, r., čufar, k., dittmar, c., esper, j., griggs, c., gunnarson, b., günther, b., gutierrez, e., haneca, k., helama, s., herzig, f., heussner, k.-u., hofmann, j., janda, p., kontic, r., köse, n., kyncl, t., levanič, t., linderholm, h., manning, s., melvin, m.t., miles, d., neuwirth, b., nicolussi, k., nola, p., panayotov, m., popa, i., rothe, a., seftigen, k., seim, a., svarva, h., svoboda, m., thun, t., timonen, m., touchan, r., trotsiuk, v., trouet, v., walder, f., ważny, t., wilson, r., zang, c. 2015. old world megadroughts and pluvials during the common era. science advances 1 (10), e1500561. doi: 10.1126/sciadv.1500561 fejér, gy. 1844a, b. codex diplomaticus hungariae ecclesiasticus ac civilis. tomi x, vols. 6, 8. typ. regiae universitatis ungarie, budae [budapest], vol. 6: 886–892, 920–922; 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(1417– 1418). magyar országos levéltár kiadványai, ii. forráskiadványok 32. akadémiai kiadó, budapest, 363, 624. nagy, i., nagy, i., véghely, d. 1878. a zichi ésv ásonkeői gr óf zichycsalád id ősb ágának okmánytára/ codex diplomaticus domus senioris comitum zichy de zich et vasonkeő, vol. 4, 558-561, 634–641. old world drought data (owda) on noaa: https://www.ncdc.noaa.gov/paleo-search/study/19419 óváry, l. 1890. a magyar tudományos akadémia történelmi bizottságának oklevél-másolatai. első füzet. magyar tudományos akadémia, budapest, 58–59. piti, f. 2010. a vay család berkeszi levéltárának 1342–1382 közötti oklevelei. nyjamé 52, 1–20 (107–111). pribyl, k. 2017. farming, famine and plague. the impact of climate in late medieval england. cham, springer, 206–207. https://www.academia.edu/37812650/kiss_before_and_after_the_great_heat_and_drought_of_1540._multiannual_trends_of_grape_and_grain_harvest_dates_in_the_vienna_hospital_accounts._in_m%c3%a9rai_d._chief_ed._._genius_loci._laszlovszky_60._budapest_archaeolingua_2018_pp._117-120 https://www.academia.edu/37812650/kiss_before_and_after_the_great_heat_and_drought_of_1540._multiannual_trends_of_grape_and_grain_harvest_dates_in_the_vienna_hospital_accounts._in_m%c3%a9rai_d._chief_ed._._genius_loci._laszlovszky_60._budapest_archaeolingua_2018_pp._117-120 https://www.academia.edu/37812650/kiss_before_and_after_the_great_heat_and_drought_of_1540._multiannual_trends_of_grape_and_grain_harvest_dates_in_the_vienna_hospital_accounts._in_m%c3%a9rai_d._chief_ed._._genius_loci._laszlovszky_60._budapest_archaeolingua_2018_pp._117-120 https://www.academia.edu/37812650/kiss_before_and_after_the_great_heat_and_drought_of_1540._multiannual_trends_of_grape_and_grain_harvest_dates_in_the_vienna_hospital_accounts._in_m%c3%a9rai_d._chief_ed._._genius_loci._laszlovszky_60._budapest_archaeolingua_2018_pp._117-120 kiss 2019 / journal of environmental geography 12 (3–4), 53–67. 67 prokop, o., kolář, t., büntgen, u., kyncl, j., bošel'a, m., choma, m., barta p., rybníček, m. 2016. on the palaeoclimatic potential of a millennium-long oak ring width chronology from slovakia. dendrochronologia 40, 93–101. doi: 10.1016/j.dendro.2016.08.001 rohr, c. 2007. extreme naturereignisse im ostalpenraum. naturerfahrung im spätmittelalter und am beginn der neuzeit. böhlau, köln– weimar–wien, 442–444. thallóczy, l., 1900. középkori gazdaságtörténeti adatok nürnberg levéltáraiból. magyar gazdaságtörténelmi szemle 7, 76–81. telelis, i.g. 2008. climatic fluctuations in the eastern mediterranean and the middle east ad 300-1500 from byzantine documentary and proxy physical paleoclimatic evidence – a comparison? jahrbuch der österreichischen byzantinistik 58, 207. doi: 10.1553/joeb58s167 tree ring drought atlas portal: http://drought.memphis.edu vajda, t. 2012. árpádés anjou-kori vízimalmaink tájalakító hatása (water mills as driving forces of landscape change in the arpadian and angevin period). in b. péterfi, a. vadas, g. mikó, and p. jakab (eds.). micae mediaevales 2. budapest: elte btk, 59–75. wagner, c., 1774. analecta scepusii sacri et profani. vol. 2. trattner, vienna, 144–145. wetter, o., pfister, c., werner, j.p., zorita, e. wagner, s. seneviratne, s.i., herget, j., grünewald, u., luterbacher, j., alcoforado, m., barriendos, m., bieber, u., burmeister, k.h., brázdil, r., camenisch, c., contino, a., dobrovolný, p., glaser, r., himmelbach, i., kiss, a., kotyza, o., labbé, t., limanówka, d., litzenburger, l., nordli, ø., pribyl, k., retsö, d., riemann, d., rohr, c., siegfried, w., söderberg, j., spring, j.-l. 2014. the year-long unprecedented european heat and drought of 1540 – a worst case. climatic change 125, 349–363. doi: 10.1007/s10584-014-1184-2. introduction sources and methods results dry spell or not? mill in very dry place: late summer 1371 temporary watermill stops working: january 1375 water body dried up due to great drought: spring 1378 potential signs of the 1393 drought in medieval hungary 1415-1416: problematic years – full of contradictions? 1417: drought or not? famine in mid-/late 1420s: any relationship to drought? the ‘perfect match’ in the year of reformation: the great drought of (1516-)1517 discussion (1516-)1517: comparable to the most severe droughts of 1473(-1474) and 1540? potential, indirect references on droughts or dry spells owda droughts – with no documentary evidence? conclusions references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. i. no. 3-4. pp. 15-20 application of self-organizing neural networks for the delineation of excess water areas szántó, g. 1 – mucsi, l. 1 – van leeuwen, b. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract in recent times artificial neural networks (anns) are more and more widely applied. the ann is an information processing system consisting of numerous simple processing units (neurons) that are arranged in layers and have weighted connections to each other. in the present study the possible application of an unsupervised neural network model, the self-organizing map (som), for the delineation of excess water areas have been examined. by means of the self-organizing map high-dimensional data of large databases could be mapped to a lowdimensional data space. within a data set, it is able to develop homogeneous clusters, thus it can be effectively applied for the classification of multispectral satellite images. the classification was carried out for an area of 88 km 2 to the south of hódmezővásárhely situated in the south-eastern part of hungary, which is frequently inundated by excess water. as input data, the intensity values of the pixels measured in six bands of a landsat etm image taken on 23rd april 2000 were used. to perform the classification, three different sized neural network models were created, which classified the pixels of the satellite image to 9, 12 and 16 clusters. by using the gained clusters three thematic maps were created, on which different types of excess water areas were delineated. during the validation of the results it was concluded that the applied neural network model is suitable for the delimitation of excess water areas and it could be an alternative to the traditional classification methods. keywords: artificial neural networks (anns), excess water, multispectral classification introduction in recent times artificial neural networks (anns) are more and more widely applied. the ann is an information processing system consisting of numerous simple processing units (neurons) that are arranged in layers and have weighted connections to each other. their construction and operating principle are based on the biological neural networks, and their significant feature is adaptiveness, i.e. they solve the problems by learning from examples and not by means of programming. since several types exist, the ‘neural network’ designation rather means a model range than a concrete process. their field of application is quite varied; sample-association, classification, optimization and similarity identification. they are applied in various fields of science, also in geography. the significance of their application is based on the sharp increase in the amount of geographical data. in recent times several data collecting techniques are widely used e.g. the multiand hyperspectral remote sensing, thus the resolution of the data rapidly increases both in geometric and attribute space. neural networks could be a really effective alternative for the analysis of the high-dimensional data. their application in the field of geography is discussed in more detail in the works of agarwal p. et al. (2008) and hewitson b. c. et al. (1994). the aim of this study is to delineate excess water areas on the basis of satellite images by using a neural network. the study area is in the vicinity of the settlement batida, situated on the left bank of the river tisza, to the south of hódmezővásárhely. the term of excess water was defined in a number of ways, and the main point was summarized by rakonczai j. et al. (2001) as follows: ‘excess water is a kind of surplus water on the surface of a certain (drainage) area or in the pores of the arable land/near-surface formations, that inhibits the growth of vegetation and damages the man-made buildings.’ excess water is a yearly recurring problem which endangers 45% of the area of the country, 60% of the arable lands, more than 4 million hectares altogether. therefore the exact delineation of these areas is highly important, for which the different remote sensing methods provide the most objective way (rakonczai j. et al. 2001). the delineation of excess water areas was carried out by the classification of medium spatial resolution multispectral satellite images. during the processing of multispectral satellite images, classification is a fundamental procedure, through which the pixels of the image are classified according to their spectral features, by mathematical methods. as a result a thematic map was created which makes it possible to visualize the information stored in satellite images in a more expressive way. the classification was performed via one type of the neural networks, the so-called self-organizing map that creates classes in the training samples by unsupervised learning. several examples could be mentioned referring to the application of neural networks in multispectral classification. according to awad m. (2010), the multispectral classification carried out by selforganizing maps is more precise than the isodata classification. in the opinion of aitkenhead m. j. et al. (2007) anns are a quick and accurate method for mapping land cover change. pacifici f. et al. (2009) carried out urban land use classification on the basis of the sample analysis of high resolution satellite images, performed by neural networks. barsi á. (1997) could be mentioned from hungary, who classified a landsat tm image by one type of the neural networks. in his opinion, this method provides as accurate results as the traditional methods. 16 szántó g. – mucsi l. – van leeuwen b. joeg i/3-4 artificial neural networks (anns) the structure of artificial neural networks (anns) is similar to the human brain in that the storage of knowledge takes place in connected processing units (neurons). a processing unit converts the weighted sum of the incoming inputs by the help of an activation function. the most commonly used activation functions are the linear function, the sigmoid function and the step function. the result obtained is sent to other neurons through the outgoing connections of the neuron (fig. 1). fig. 2 structure of an artificial neural network (ann) the neurons are arranged into layers. every net has an input layer for feeding input data and an output layer for visualization of the results. between these layers a number of hidden layers could be found (fig. 2). the learning of the net is realized by the modification of the weights between the neurons. supervised and unsupervised learning methods could be distinguished. in case of supervised learning the training set includes both the input samples and the output samples. during an iteration process, the weights of the connections between the neurons undergo such changes that the appropriate result is added to the given input sample. in case of unsupervised learning only the set of input samples is known, while the output neurons compete for the input samples on the basis of certain similarity aspects. the weight vectors of winning neurons vary based on their added input value. by the help of such types of nets, regularities could be observed in the distribution of the sample data. there are several types of anns, which could differ in certain elements from the general model. they have several advantages over the traditional methods, as their application does not depend on the statistical distribution of the input data, they are not sensitive to incomplete and disturbed samples and are able to process huge amount of data. self-organizing map the self-organizing map (som, kohonen map) applied in this research was created by kohonen (kohonen t. 2001), and this is the most widespread ann which carries out unsupervised learning. it classifies the ndimensional input samples (n>2) by means of unsupervised learning, and adds them to the elements of a lowerdimensional output layer. the similar samples are associated with the neighbouring elements of the output layer, i.e. apart from the distribution of the samples in the input space, it also learns the topology between them. the self-organizing map performs data clustering and dimension reduction at the same time. therefore it is suitable for the solution of different problems and it can be an alternative besides other methods e.g. the principle component analysis and the k-median clustering. self-organizing maps are made up of two layers, the input and output (or kohonen) layers, that are connected with each other through all of their neurons (fig. 3). data is fed into the input layer, which has the same fig. 1 sketch of a neuron joeg i/3-4 application of self-organizing neural networks for the delineation of excess water areas 17 number of neurons as the number of input variables. classification takes place in the kohonen layer, the number of classes created during the learning process will be equal to the number of neurons located here. in this layer the neurons are located in a 1d, 2d or 3d topological position that enables connection between the neighbouring neurons. the 2d topology is the most widespread, in which the elements are arranged in square grid or hexagonal pattern. each neuron has an n-element weight vector, where ‘n’ equals to the dimension of the input vector. the initial weight vectors of the neurons are usually determined by random numbers or, for the acceleration of the learning process, along the first two principle component vectors of the sample data. fig. 3 self-organizing map (kohonen t. 2001) the learning of the net takes place according to the kohonen rule, on the basis of which the processing units learn competitively. the model searches for the weight vector of the most similar i.e. the winning neuron in each input sample. this is usually calculated on the basis of euclidean distance. the model modifies and shifts the weight vector values of the winning neuron and those in its certain topological neighbourhood circle towards the value of the input sample. the degree of modification at t time is determined according to the kohonen rule (borgulya 1998): δwj(t) = η(t)hcj(t)(x(t)-wj(t)), where wj is the weight vector of the j th element η is the learning rate decreasing in time hcj is the neighbourhood function, which decreases from the winning neuron ‘c’ x is an input sample vector. at the beginning of the learning process a larger learning rate and neighbourhood circle are used, which allow large-scale modifications providing the addition of the similar input samples to the neighbouring neurons. by the decreasing of the learning rate and the neighbourhood circle, the fine-tuning of the model is the next step towards the end of the learning process. the learning algorithm of a self-organising map can be described as follows (hewitson et al. 1994): 1. the initiation of the net by giving the geometry and the number of neurons. 2. giving the initial weight vectors of the neurons. 3. giving a sample case to the net. 4. determination of the winning neuron connected to the sample. 5. modification of the weight vectors of the winning neuron and the topologically neighbouring neurons based on the kohonen rule. 6. slight reduction of the learning rate and the neighbourhood circle. 7. repetition of the last four steps until the convergence is reached. the different types of visualization of the created model make the analysis of the results possible. if the distribution of the input sample in the data space is examined, the position of the neurons in the data space, their distance from each other or the component planes could be visualized. the component planes represent the strength of the neuron weights regarding each variable. through the examination of the similarity of the component planes, the connections between the variables could be detected. self-organising maps can be used together with other visualization tools, thus in case of geographical applications they can be connected to geographical maps or integrated into geographical information systems. study area and data used the 88 km 2 study area is situated in the vicinity of the settlement batida, to the south of the town of hódmezővásárhely, in the southern part of tiszántúl (the region east of the river tisza) in the great hungarian plain. the area is covered by young alluvial deposits, on which vertisols and fluvisols were formed. most of it is under agricultural cultivation. there are several abandoned river meanders and point bars in the study area. classification was performed on the basis of medium resolution landsat 7 etm satellite images taken on 23rd april 2000. for the validation of the results color infrared aerial photographs of the lower tisza valley region taken by the argos studio of vituki plc. on 23rd march 2000 were used. numerous software exist for the training and visualization of self-organising maps, which were also included in some large software packages and in software made for this special demand (e.g. som_pak developed by kohonen). their integration with geographical information systems has not really been widespread yet (coleman a. m. 2008), but certain programmes offer such tools (e.g. 18 szántó g. – mucsi l. – van leeuwen b. joeg i/3-4 idrisi). matlab was chosen for our analysis, as it provides more complex analysing and visualizing methods. matlab is a mathematical program system with a special programming language, developed for numeric calculations. it is applied in many fields and a large number of modules are available for the different applications. in our research the tools of the neural network toolbox were applied, which can be used for the planning, simulation and visualization of different types of neural networks, among others the self-organising maps. process of analysis matlab offers many kinds of parameterization possibilities during the planning process of the self-organising map. the size of the net, the type of the topology and the neighbourhood function, the size of the neighbourhood circle and the number of the training iterations could be set. three nets of different sizes were created for the classification, the output layers of which consisted of 3x3, 3x4 and 4x4 processing units arranged in a 2d hexagonal topology. the process of the analysis is going to be presented through the example of a net consisting of 4x4 neurons (fig. 4). fig. 4 self-organising map consisting of 4x4 neurons intensity values measured on six bands (blue, green, red, near infrared and two medium infrared bands) of the pixels of the landsat etm satellite image were used as input data. the training process consisted of one thousand iterations, that is, the whole set of samples was fed one thousand times to each of the three nets. after training, the simulations of the models were run in case of each net. figure 5 demonstrates that how many input samples were added to the individual neurons, for instance how many pixels were sorted to each class in case of a net consisting of 4x4 neurons. the further evaluation of the results was performed by arcgis software, and included the creation of thematic maps by merging the clusters according to the appropriate theme, and the creation of the required legend. fig. 5 number of inputs added to the individual neurons results for the delineation of inland water areas it was practical to merge the clusters into a small number of classes, because the individual clusters could have been specified only by the help of an exact field work. analysing the composite planes, it could be determined to which neurons were the pixels having different reflectance features added. on the basis of this the following 5 classes could be separated: open water surface, dry soil, water saturated soil, vegetation and vegetation in water. figure 6 shows that pixels with the same reflectance values were projected to the neighbouring neurons, as a characteristic of the self-organising map. the classes created were represented in a thematic map as well (fig. 7). fig. 6 position of the classes of excess water mapping joeg i/3-4 application of self-organizing neural networks for the delineation of excess water areas 19 on the thematic map, created on the basis of the results of the three neural networks, open water surfaces and even those, which are not entirely covered with water are well separable. table 1 shows how large the differences were in the extensions of the different land cover types. it was not possible to quantify the accuracy of the results owing to the lack of appropriate field survey data. however, excess water areas of great extension could be delineated in all the three cases by comparing the thematic maps with aerial photographs (fig. 8). it is the delineation of transitional classes where there are more considerable differences as it is difficult to determine how high moisture content indicates another class. in our opinion, the application of more neurons makes it possible to determine this boundary more precisely. conclusions as a result of this present research, it could be concluded that the type of neural network applied is suitable for the thematic classification of satellite images. by the help of this method excess water areas have been successfully delimited in the study area. for the examination of the effectiveness of this method, it will be required to compare the results with those gained from traditional classification methods. in the application of self-organising maps, the possibility of their extension is a great asset, since this way they can simultaneously manage data from different sources. thus, besides the spectral information of the satellite images, other data could also be used for the classification, for instance elevation models and other thematic layers, e.g. soil and geomorphological fig. 7 classification of the settlement batida and its surroundings table 1 differences in the extension of the classes for the three models 3x3 3x4 4x4 open water surfaces 2.03% 1.74% 1.45% water saturated soil 13% 19.65% 15.41% vegetation in water 12% 10.2% 9.62% dry soil 49.3% 41.48% 45.15% vegetation 23.65% 26.93% 28.35% 20 szántó g. – mucsi l. – van leeuwen b. joeg i/3-4 maps. the shape recognition function of the selforganising maps could make it possible to identify frequently inundated landforms, for example abandoned river meanders and point bars. references agarwal p. – skupin a. 2008. self-organising maps: applications in geographic informations science. new jersey: john wiley & sons ltd. 214 p aitkenhead m. j. – lumsdon p. – miller d. r. 2007. remote sensing-based neural network mapping of tsunami damage in aceh, indonesia. disasters 31/3: 217-226 awad m. an unsupervised artificial neural network method for satellite image segmentation. the international arab journal of information technology 7/2: 199-205 borgulya i. 1998. neurális hálók és fuzzy-rendszerek. budapest: dialóg campus kiadó. 230 p barsi á. 1997. landsat-felvétel tematikus osztályozása neurális hálózattal. geodézia és kartográfia 49/4: 21-28 coleman a. m. 2008. an adaptive landscape classification procedure using geoinformatics and artificial neural networks. unpublished msc thesis, amsterdam. 195 p hewitson b. c. – crane r. g. 1994. neural nets: applications in geography. dordrecht: kluwer academic publishers. 194 p kohonen t. 2001. self-organizing maps. berlin: spinger verlag. 501 p miller d. m. – kaminsky e. j. – rana s. 1995. neural network classifation of remote-sensing data. computers and geosciences 2/3: 377-386 pacifici f. – chini m. – emery w. j. 2009. a neural network approach using multi-scale textural metrics from very highresolution panchromatic imagery for urban land-use classification. remote sensing of environment 113: 1276-1292 rakonczai j. – mucsi l. – szatmári j. – kovács f. – csató sz. 2001. a belvizes területek elhatárolásának módszertani lehetőségei. i. földrajzi konferencia, szeged fig. 8 comparison of the delimited excess water areas with aerial photographs image based surface temperature extraction and trend detection in an urban area … journal of environmental geography journal of environmental geography 9 (3–4), 13–25. doi: 10.1515/jengeo-2016-0008 issn: 2060-467x image based surface temperature extraction and trend detection in an urban area of west bengal, india sk ziaul*, swades pal department of geography, university of gour banga, malda 732103, west bengal, india * corresponding author, e-mail: skziaul87@gmail.com research article, received 2 june 2016, accepted 25 october 2016 abstract rapid urbanization and change of landuse/landcover results in changes of the thermal spectrum of a city even in small cities like english bazaar municipality (ebm) of malda district. monitoring the spatio -temporal surface temperature patterns is important, therefore, the present paper attempts to extract spatio -temporal surface temperature from thermal band of landsat imageries and tries to validate it with factor based land surface temperature (lst) models constructed based on six proxy temperature variables for selected time periods (1991, 2010 and 2014). seasonal variation of temperature is also analyzed from the lst models over different time phases. landsat tirs based lst shows that in winter season, the minimum and maximum lst have raised up 2.32c and 3.09c in last 25 years. in pre monsoon season, the increase is much higher (2.80c and 6.74c) than in the winter period during the same time frame. in post monsoon season, exceptional situation happened due to high moisture availability c aused by previous monsoon rainfall spell. trend analysis revealed that the lst has been rising over time. expansion and intens ification of built up land as well as changing thermal properties of the urban heartland and rimland strongly control lst. factor based surface temperature models have been prepared for the same period of times as done in case of lst modeling. in all seaso ns and selected time phases, correlation coefficient values between the extracted spatial lst model and factor based surface tempera ture model varies from 0.575 to 0.713 and these values are significant at 99% confidence level. so, thinking over ecological growth of urban is highly required for making the environment ambient for living. keywords: land surface temperature, landsat tirs, factor based lst models introduction knowledge of land surface temperature (lst) and its temporal and spatial variations within a city environment is of prime importance to the study of urban climate and human–environment interactions (stathopoulou and cartalis, 2009; sharma and joshi, 2013; singh and grover, 2014; alavipanah et al., 2015). the retrieval of the lst from remotely sensed tir data has attracted much attention, and its history dates back to the 1970s (mcmillin, 1975). urban heat island (uhi) and magnitude of the difference in observed ambient air temperature between cities and their surrounding rural regions have been a concern for more than 60 years (landsberg, 1981). nichol and hang (2012) reported that there is a clear cut difference of temperature between rural and urban region and this gap is usually 3-4c. one of the earliest uhi studies was conducted in 1964 (nieuwolt, 1966) in the urban southern singapore. extensive urbanized surfaces modify the energy and water balance processes and influence the dynamics of air movement (nichol and hang, 2012). afterward, many scientists (giridharan et al., 2004; neteler, 2010; schwarz et al., 2011; xiong et al., 2012; zhang et al. 2013; li et al. 2014; kuang et al., 2015b; alavipanah et al., 2015) have worked in this field emphasizing different cognitive issues. lst is a key factor in physical dispensation of land surface at different spatial scale, and it generalizes the results of the interaction between land surface and atmosphere, exchange of matter and energy (wan and dozier, 1996; alavipanah et al, 2015). in the general assessment model of sustainable development and lst change, the change of lst is regarded as an important criterion upon which the evaluation of environmental quality and social and economic development policy can be based (keller, 2008; dai et al., 2010). dynamic variability of lst seasonally and diurnally encouraged scholars to address this fact. seasonal variation is well documented by yuan and bauer (2007) and deosthali (2000) and they found that at night, the center of the city appeared as both heat and moisture island whereas at the time of sunrise as heat and dry island. in 2008 more than half of the world's population were urban dwellers and the urban population is expected to reach 81% by 2030 (unfpa, 2007). this acceleration of urbanization is very high both in intensity and area in developing countries like india. so, studying of the environmental conditions is necessary for proper planning or policy review. at the same time, it is already established that low population density is associated with lower lst values (li et al., 2014) and conversely it is true that higher temperatures are associated with densely populated urban areas. 14 ziaul and pal (2016) intensity of lst is related to patterns of land use/cover changes (lulc), e.g. the composition of vegetation, water and built-upand their changes (ding and shi, 2013; li et al. 2014; grover and singh, 2015; kuang et al, 2015 a, b). both horizontal and vertical urban expansion, spacing between buildings, building materials, location of public places, bus stoppage, railway station, major and minor industrial hubs etc. influence temperature concentration (park, 1986; alavipanah et al., 2015). rising population and building density are also accelerating factors of lst (schwarz et al., 2011; peng et al., 2012). the spatial extent of concrete cover and material composition is another major vector of spatial pattern of lst (xiong et al., 2012; kuang et al., 2015b). growing population density, greater consumption of energy etc. can also aggravate temperature condition (zhang et al, 2013; li et al., 2014). clearly, the built-up land exhibited the highest lst, followed by bare soil, water body, and vegetation in all three periods as reported by weng (2001), weng and yang (2004) and chen et al. (2006). in forested area, temperature is almost 4.5-5c lower than bare land (buyantuyev and wu, 2010). it has been shown from both a theoretical and a practical point of view that the normalized difference vegetation index (ndvi) derived from satellite data is a good indicator of vegetation density (grover and singh, 2015; gulácsi and kovács, 2015). vegetation can reduce lst by 13°c and considered one of the dominant factors for better health condition and a positive human comfort (gémes et al., 2016). both directionality of values (positive and negative) carry important role for regulating surface temperature. positive and negative respectively indicate high vegetation density and high moisture which can help to reduce surface temperature (choudhury, 1987; kibert, 2012). in most cases, a negative correlation between ndvi and lst is found (xiao et al., 2007; zhang et al., 2013), although high canopy cover area is not a prime determinant because plant species, leaf area, soil background, and shadow can all contribute to the ndvi variability (james and charles, 2014). yuan and bauer (2007), li et al. (2012) revealed that the relationship between ndvi and lst varies seasonally. james and charles (2014) also established that water bodies exhibits minimum land surface temperature than other landuse/land cover. normalized difference building index (ndbi) indicates built up area concentration over space. most of the previous studies recorded high surface temperature in the urban built up areas (chen et al., 2006; liu and zhang, 2011; essa et al., 2012) although its magnitude varies significantly due to variability in composition of building materials and density of buildings. vertical growth is also responsible for intensifying lst (park, 1986). yuan and bauer (2007) suggested that the percentage impervious surface cover as a more reliable metric for quantitative analysis of lst over different seasons for urbanized areas. major road axes and railway station arecharacterized by high traffic and population concentrations and often have a higher temperature (weng et al., 2004). for preparing multi criteria approach based spatial modeling in different sector, the use of gis has received valued reputation (carver, 1991; eastman, 1997). the boolean overlay operations (no compensatory combination rules) and the weighted linear combination (wlc) methods (compensatory combination rules) are two major dimensions of multicriteria suitability modeling. they have been the most often used approaches for different sorts of landuse suitability analysis (malczewski, 2004). all the previous work in this approach is based on weighted additive average of the data layers selected for the suitability models. but the way of providing weight to the data layers according to their importance are different. for weighting the data layers pca based approach (khatun and pal, 2016), analytic hierarchical approach (ahp) (satty, 1980) etc. are used. ground measurement cannot provide wide spread data of different places at a time therefore contribution of satellitebased thermal infrared data is applied frequently in the developed nations. in india, this advanced method for spatial surface temperature extraction is not often applied. growing urbanization rate, intra-urban density etc. require such study for rethinking about renewal of urban planning based on satellite data based temperature analysis at different spatio-temporal scale. in the third world countries like india, the density of meteorological stations is so sparse over space (average density of meteorological station is 1/500 km2, in plain region it is 1/520 km2, in elevated land it is 1/260-390 km2 and in hilly region it is 1/130 km2 (raghunathan, 2010) that there is no other alternative than to use tir satellite data based temperature extraction. another major advantage of this data is that it provides pixel to pixel temperature information and produces micro level variation of temperature over space. such data also helps to predict the local driving factors of surface temperature. kawashima et al. (2000) documented a relation between mean air temperature and mean surface temperature. also they rightly mentioned that this relation varies with altitude. they recorded that mean air temperature is 7 to 9.6c larger than the mean surface temperature and obviously difference is higher at lower elevation. adjusted r2 ranges from 0.91 to 0.98 when regression is carried out between spatial air temperature and lst distribution models because of their high spatial associationship. present paper attempts to capture spatio-temporal variation of land surface temperature over the english bazar municipality (ebm) and its peripheral areas of west bengal state of india. furthermore, a factor based lst model was developed for understanding the relative variation of temperature over the region. comparison of the actual land surface temperature data extracted from tir is done in response to the factor based lst models constructed using major controlling factors. main motive behind the factor based modeling is to find out it can substitute tir satellite data based lst model. also it aims to investigate whether the selected factors are effective for explaining spatial lst patterns. priority analysis of the local level driving factors of temperature variation is carried out to understand the dominant driving factor of lst. seasonal variation of temperatures at each time period (pre-monsoon, monsoon and winter) is analyzed to show seasonal extremities in this sub humid urban region. trend analysis of temperature in different seasons over the temporal scale is also carried for identifying changing degree and intensity of lst. in brief, two sets of lst models have applied in this work. first approach is landsat tir based lst modeling and second approach is proxy factor based lst image based surface temperature extraction and trend detection in an urban area … 15 modeling for the same phases. ultimately, spatial correlation coefficient between two sets of models have been calculated to test the accuracy of the factor based models. study area the present study area consists of 29 wards of english bazar municipality (ebm), 16 surrounding mouzas (smallest administrative or land revenue unit) from english bazar block and 11 mouzas from old malda block (relatively larger administrative unit composed with several mouzas) covering an area of about 5500 ha (fig. 1). the entire study area comes under diara tract of west bengal with fertile fine grain silty clay carried out by river ganga and its distributary kalindri river and mahananda river, located at the northern and eastern margins of the study area. the average elevation of the region is 17m above msl. the water table is moderately deep (5 m to 10 m under surface) with moderately high seasonal fluctuation (24m). (central ground water board, 2010) and it may control evaporation as well as land surface temperature. north western part of the present study area is covered with mango orchards. chatra wetland (perennial) is considered the lungs of the town, and is located at the boundary zone of the town. over time, this wetland area is captured by built up area. climate of this region is characterized by sub tropical monsoon with seasonal wet and dry spell of rainfall, cold and hot spell of temperature. the year is sub divided by four major seasons: (1) winter season (january and february), (2) pre-monsoon season (march to may) with little rain and high temperature and evaporation, (3) monsoon season (june to mid-october) with maximum (about 82% of total rain) rain and high temperature and (4) post-monsoon season (mid-october to mid-december) with steady decline of rainfall and temperature. the post monsoon effect is less distinct. average annual rainfall of this basin as gauged by malda meteorological station is 1444 mm. monthly variation of rainfall and temperature is noticeable (table 1). the average potential evaporation, being one of the controlling factors of surface temperature, was 73 mm/year between1901 and 2014 in the area. fig. 1 study sites showing selected mouzas, rivers, wetland, nh34, railway line, station and major market points table 1 average monthly temperature and rainfall conditions between 1991 and 2014 climatic indicator january february march april may june july august sept. oct. nov. dec. tmax (c) 23 26.7 32.3 35 34.7 33.7 32.2 32.2 31.7 30.8 28.5 24.8 tmin (c) 10.1 12.1 16.5 21.7 24.3 25.7 25.9 26 25 22 16.9 11.9 rainfall (mm) 10.9 10.8 11 39.1 117.5 229.4 353.1 302.4 296.6 91.8 12.3 10.3 16 ziaul and pal (2016) the town possesses a good infrastructure and facilities. two railway stations e.g. gourmalda and malda town are located at southern and northern part of this area. railway line and national high way (nh) 34 perforate the town from south to north. two main markets, netaji market/rathbari market and chittaranjan market are located at the heart of the town and are considered as central business district (cbd) of this commercially improved town (see fig. 1). the total number of population and house hold in the study area are 291612 people and 61803 households respectively according to the census of 2011. additionally, it is also needed to mention that apart from these, the amount of people in the city is more than 50 % higher due to people from outside the city. the town is the main market town of the larger catchment of the malda, murshidabad and dinajpur districts of west bengal and larger part of eastern jharkhand state of india. most of the cases, spacing between houses is about to 45-60cm, exemplifying the dense building pattern. materials and methods data and image pre-processing landsat 5 and landsat 8 are used for both landuse/landcover mapping and lst modeling (path/row 139/43; spatial resolution for tir band of landsat 5 is 120m and for landsat 8 it is 100m.; spatial resolution for other bands is 30m in landsat 5 and band 1 to 7 for landsat 8). the extraction of lst is based on landsat satellite images acquired through the usgs earth resource observation systems data center, which are corrected for radiometric and geometrical distortions of the images to an acceptable quality level before delivery. the landsat image is further rectified to a common universal transverse mercator coordinate system. noise diminution is essential for remotely sensed satellite images, particularly for the thermal infrared (tir) band. the inherent noise may affect the retrieval of brightness temperature or lst. methods the methodology consists of three sections (fig 2): extraction of lst from landsat images, multicriteria lst modelling, spatial association between landsat based lst model with multicriteria lst (mclst) model. the first section adopted two approaches for lst modeling. 1) landsat tir based extraction of lst and 2) proxy temperature factor based multicriteria lst modeling. first approach is entirely based on thermal band of landsat images of different time periods and the second approach is based on six proxy temperature factors as indicated in table 2. entire methodological work flow is illustrated in figure 2. fig. 2 flow chart showing methodological workflow image based surface temperature extraction and trend detection in an urban area … 17 table 2 selected proxy parameters and associated sources of data set name of the parameters source(s) 1) land use sensor: imageries of landsat 5, nov., 2013 (path/row:139/43; band used: g, r, nir; spatial resolution: 30m. ), land use map, 2014 of land reform deptt., west bengal 2) ndbi extracted from landsat 5 and 8 images 3) ndvi satellite image of landsat 5 and 8 based on townshend and justice, 1986 4) ndwi satellite image of landsat 5 and 8 based on mcfeeters, 1996 5) major road extracted from google image, dst map, malda district 6) railway station extracted from google image and field check through gps 7) land surface temperature tirs 1 & tirs 2 band of landsat 8 and thermal infrared band of landsat 5 lst extraction and modeling approach 1 deals with extraction of lst from thermal band of the selected sensors is well discussed with a good number of merits and demerits by the xiong et al. (2012), zhang et al, (2013), li et. al. (2014). it is multistep methods i.e. conversion of the digital number (dn) to spectral radiance, conversion of spectral radiance to at satellite brightness temperature, lst extraction, conversion of lst from kelvin to degree celsius. this method is quite different for each sensor (landsat 5, 7 etc.). all these things are well defined in the respective guidelines published by landsat project science office (2002). in this present work, guidelines of the same have been followed for working out lst from landsat imageries. approach 2 deals with six proxy data layers (table 3). these layers are (1) landuse/landcover, (2) normalized differential vegetation index (ndvi) map, (3) normalized differential water index (ndwi) map, (4) normalized differential built up index (ndbi), (5) major roads and (6) railway station. here some other factors theoretically can be adopted like relief, rainfall etc. but these layers are not taken here because of their minimal influence within such a small spatial area. as wlc process executes on the basis of raster based weighted linear combination (wlc), it is required to convert each with an equal. ndwi, ndvi, ndbi, landuse/landcover layers have been extracted as raster layers, so there is no need for conversion for these four layers. but other two layers i.e. major roads and railway station layers are in vector forms and these are needed to be converted into raster layers. for this, proximity maps have been constructed from these layers. it is assumed that the area nearer to the roads or railway lines or stations will be affected more by increased lst and gradually it will decrease with increasing distance from roads or railway lines. after converting the selected layers to raster format, each attribute (map layer) is categorized into 10 classes ranking 1 to 10,wherea higher rank reflects a potentiality higher lst. landuse/landcover classes have been ranked based on the potential contribution toward lst. for example, built up class has assigned maximum weight. here relative ranking of the landuse/landcover class is done based on subjective priority. to fulfill this purpose, all the attributes have been reclassified into 10 classes following natural break method and ranked accordingly. the logic behind ranking to intra attribute classes from 1-10 is described in table 3. weightage of each attribute has been defined objectively (table 4) considering the degree of correlation of each driving factor with land surface temperature generated for different years. the logic behind this consideration is that highly correlated parameters maximally explain the spatial variation of temperature. normalization of respective weights (values of r for respective parameters) based on dimension index have been performed for frame it in a scientific scale. it is calculated for distributing relative weight of all the parameters. here total normalized weight is 1. the parameter shares maximum out of 1 is emerged as dominant parameter. the result of each normalized value is called attribute weight. weights of the parameters for different seasons in respective years are different due to having some dynamic variables like landuse/landcover, built up area, water bodies, canopy coverage etc. therefore nine models have been articulated for different seasons in the selected years. table 3 modes of ranking of the intra sub class of parameters name of the attribute (j) highest rank indicates at 10 point scale logic behind 1) land use 10 rank at built up land concrete area has high temperature emissivity 2) ndbi 10 rank at highest intensity class high intensity built up land emits maximum temperature 3) ndvi 10 rank at ‘0’ value above and below 0 value canopy cover and water availability increases which may reduce temperature 4) ndwi 10 rank at lowest ndwi value it does indicate water concentration; more concentration of water bodies mean less temperature and vice versa 5) major road 10 rank at road adjacent zone highly dense traffic in all roads concerned specifically national high way 34 insists temperature rise 6) railway station 10 rank at near to the railway station being a nodal centre, a good number of trains ups and down and huge number of passengers uses this station as nodal point expression of weight calculation is as follows (eq. 1): 1 rj j n r j a w j    (eq. 1) where wj=weight of jth parameter; ajr= correlation coefficient of jth attribute; σjr = summation of correlation of all jth variable. 18 ziaul and pal (2016) rank of all sub classes under each attribute is then multiplied by the defined weight of each individual attribute. this function can be presented using equation 2: 1 n ij j j wlc a w    (eq. 2) where, aij= ith rank of jth attribute; wj= weightage of jth attribute. this weighted linear combination has been done using raster calculator tool in arcgis environment. weight of the attributes for different other periods has been calculated based on their respective correlation coefficient values. see table 6 for calculated weights of the parameters for different time phases. calculation of the entire process is represented in table 4 showing the case of january, 2014. table 4 pattern of reclassification of the parameters, ranking and weighting of the parameters of january, 2014 parameters sub-class rank weight of parameters 1) ndbi natural breaks 1-10 0.382 2) ndvi natural breaks 1-10 0.042 3) ndwi natural breaks 1-10 0.064 4) land use/ land cover water bodies & water hyacinth 1 0.336 mango orchard 3 agricultural land 6 fallow land 8 built up land 10 5) major road (distance from major road) natural breaks 1-10 0.154 6) railway station (distance from station) natural breaks 1-10 0.022 after preparing the multicriteria spatial lst model based on controlling factors and the landsat tir based lst model(s), spatial correlation coefficient between them has been calculated to judge the level of spatial association. strong correlation coefficient (r) does mean higher level of spatial coincidence and vice-versa. chen et al (2006) and ogashawara and brum bastos (2012) focused on the quantitative relationship between lst and temperature controlling factors by using correlation coefficient analysis. in this present work, their line of thinking has been followed. methods for framing data layers used for multicriteria lst modeling this section describes how ndvi, ndwi, ndbi and others have been prepared for constructing multicriteria lst models. for ndvi extraction, method of townshend and justice, (1986) is used.     nir band r band ndvi nir band r band    (eq. 3) where, nir=near infrared band (band 4 of mss and tm), r=red band (mss band 2, tm band 3). values ranges from -1 to +1, where negative values normally are associated with water and where positive values indicate vegetation mass. in principle, higher values are linked with higher vegetation density. for extracting ndwi, equation presented by mcfeeters (1996) is used:     green band nir band ndwi green band nir band    (eq. 4) where green is the green band (mss band 1, tm band 2) and nir is the near infrared band (band 4 of mss and tm). this value ranges from-1 to 1. value nearer to 1 indicate greater possibility of low lst. normalized differential built up index (ndbi) has been calculated following zha et al (2003):     mir band nir band ndbi mir band nir band    (eq. 5) where, mir is the mid infrared band (tm band 5, oli band 6) and nir is the near infrared band (tm band 4, oli band 5). ndbi value ranges from -1 to 1. value nearer to 1 means greater possibility of high lst. the land use data set has been prepared from landsat imageries of the respective periods mentioned in table 2. supervised image classification techniques (non-parametric rule: maximum likelihood) have been used for landuse/landcover (lulc) classification. accuracy assessment has been done by cross checking 139 sites through gps survey and google earth images. from this assessment, it was found that the accuracy assessment generated from the supervised classification technique showed an overall classification accuracy of 84.45% with kappa statistic of 0.829, which indicates a very good agreement (monserud and leemans, 1992) between thematic maps generated from image and the reference data. road and railway lines have been digitized from google earth image, toposheet of survey of india and those vector layers have been converted into raster layers through proximity or distance mapping. actually, ten equidistance buffer classes have been made both from roads and railway line individually. method for spatial association between landsat based lst model with multicriteria lst (mclst) model most of the previous work across india in this field have extracted surface temperatures but these were not validated with any reference standard datasets collected from meteorological monitoring stations. as only one meteorological station is available over the present study area, it is difficult to validate thespatio-temporal data with meteorological data available there on. authors here attempted to compare their models with some multicriterialst models created based on major locally dominant temperature driving factors. after extracting lst from tirs of landsat and constructing multicriteria lst model, simple image based surface temperature extraction and trend detection in an urban area … 19 correlation coefficient (r) between these two layers for different seasons in the selected years has been calculated. it is being considered that higher degree of r value means strong spatial association. student’s ‘t’ test has been carried out for assessing degree of significance level of the calculated correlation at 95% and 99% confidence levels. a strong spatial relation would indicate that multicriteria lst models can be used for assessing relative lst pattern over the study area. for finding out dominant factor of lst, correlation coefficient of the selected factors with surface temperature layers of the respective periods have been calculated. strongly correlated parameters are considered as dominant factors. this is calculated during multicriteria lst model building. results and discussion results extracted from data layers earlier it is mentioned that six data layers have been prepared for constructing multicriteria lst modeling. in this section result of the individual layers has been depicted. through supervised image classification, six number of major landuse/landcover classes have been identified with an accuracy level of 84.45% with kappa statistic of 0.829. out of total area (~5500 ha), 42.24% is covered with built up land followed by mango orchard (24.15%). the core part of the study area is composed of built up land and it spreads along the major roads and railway line outside the core. if only core area is considered, more than 78% of the area is built up area. such built up area concentration is highly effective for enhancing lst. the ndbi pattern shows that the maximum intensities (nbbi score: 0.1600.179) of built up area are found at the core part and also it increases even in the peripheral land. over time, greater proportion of study area comes under this intensity of ndbi. ndvi value is recorded maximum (0.292-0.487) in the north western part of the study area where one denser mango orchard is located. such value is only found in the peripheral part of the study area. this value decreases over time over the major parts, especially in the core parts. from this result it can be stated that there is a negative relation between ndbi and ndvi. ndwi values with maximum intensity are only (0.288-0.422) found in the river mahananda at the eastern side and chatra wetland at the western side of the study area. landsat image based lst change seasonal temperature dynamics (winter, pre-monsoon and monsoon) in 1991 usually, temperature is confined within the range of 14.41-20.34c during january, 1991 (fig. 3a). out of total area, 32.83% area represents temperature from 16.18 16.77c followed by 24.8% area is represented by 16.77 17.37c temperature. more than 83% is characterized by the temperature ranges from 16.18-18.55c. mean temperature of this study area in this time was 17.24˚c and the coefficient of variation (cv) was 4.04%.core urban area is sensitive to high temperature. april and may of this year show that the maximum air temperature was 40c or more. but at present case surface temperature ranges from 23.99c to 34.64c (fig. 3b). low antecedent moisture and lack of rainfall triggered by nor wester (a kind of local storm with rain) might enhanced temperature a little bit. within this temperature spectrum, 29.31 30.37c temperature covers 20.97% of the total area followed by 30.37 31.44c temperature in 20.66% of the area. more than 81% area possesses temperature between 27.18-32.5c. north western and south eastern part of the study area exhibit relatively low range of temperature due to the bagbari mango orchard and chatra wetland. only in april, the wetland area is prominent due to its distinct oceanicity factor. expectedly, areal coverage of high temperature is maximum in this time. from temperature condition, it is also clear that urban spread is maximum in the eastern part of the main town following river mahananda and north western part of the main town along main concrete road (national high way) which connects the western and north western part of the malda district with district town (english bazar municipality). in october of the monsoon month, due to frequent rainfall, despite having high temperature potential, temperature is self regulated. in this year temperature ranges from 21.66c to 28.09c (fig. 3c). about 89% spatial extent is characterized by 22.30c to 24.87c temperatures. spatial character of moisture availability regulates temperature over space. in temperature distribution, there is no such continuity as exhibited in figure 3c. except main town most part of the peripheral area shows quite lower temperatures. within main town variation of temperature is 27.64% and it is about 64.25% in the peripheral area. seasonal temperature dynamics (winter, pre-monsoon and monsoon) in 2010 in winter season, 2010 range of temperature was 16.72c to 22.98c (fig. 3d), which is 2-2.5c higher both from lower and upper limits than1991 of the same season. out of total area, 75% area is characterized by temperature level ranges from19.22c to 21.10c. mean and cv of temperature of this phase are respectively 19.97c and 4.11%. temperature spread is high both in western and eastern periphery of the main urban land. in the peripheral area rising trend of surface temperature is also identical with core urban area. in pre monsoon or summer season, 2010 temperature was within the range of 26.83c to 36.98c which is 3.20c higher than 1991. this lst is about 7c lower than mean air temperature of the same period (fig. 3e). increasing trend of temperature is also reflected in air temperature. out of the total area, 77% was characterized by a temperature ranged from 28.86c to 33.93c. mean temperature in this period was 31.47c. and coefficient of variation (cv) was 5.32% which was 0.99% higher than in 1991. the northern part of the main urban area recorded the maximum temperature. this area is characterized by one of the main dense market (netaji market), busiest traffic node and garlands of hard ware shops. 20 ziaul and pal (2016) the mean lstwas 1.98c higher thanin 1991 in the monsoon season. in 2010, the lst was in range of 22.98c to 30.58c (fig. 3f). out of total area, 86.08% was characterized by temperatures ranging from 23.73c to 26.01c. the mean temperature was 25.37c and the cv is 4.70% (table 5). seasonal temperature dynamics (winter, pre-monsoon and monsoon) in 2014 in the winter period of 2014, the lst ranged from 20.17c to 27.30c and the mean temperature was 23.39c which was 3.42c higher compared to 2010 (fig. 3g). the cv values in this season in all phases establish the fact that there was marginal increase of lst (table 5). in the summer season of 2014, the lst varied from 25.22c to 34.60c and mean temperature was 30.36c which was1.11c lower than during the previous phase (fig. 3h). actually, 4days antecedent moisture caused by nor wester lowered surface temperatures. out of the total area, 87% was characterized by temperatures between 28.03 to 32.72c. in the monsoon of 2014, the lst ranged from 23.63c to 33.66c and the mean temperature was 28.70c which was 3.33c higher than in 2010 (fig. 3i). the lowest temperature limit had increased by 0.65c and the upper temperature limit with 3.08c compared to the same period in 2010. out of total area, 87.75% was characterized by temperatures between 26.63c and 30.65c. the present work shows that not only the metropolitan city, but small urban centre like ebm are also gaining temperatures, which is not a good sign for the ambient living conditions. figure 4 clearly displays the comparative pattern of areal proportion under different fig. 3 land surface temperature a) january 1991 b) april 1991 c) october 1991 d) january 2010 e) april 2010 f) october 2010 (g) january 2014 (h) april 2014 (i) october 2014 based on landsat images image based surface temperature extraction and trend detection in an urban area … 21 range of temperature since 1991 to 2014 both for summer and winter periods. from this diagram, it can be observed that a larger proportion of the area has shifted to higher temperature classes. for example, only 2.3% area was under the lst above 33c in 1991 but it is raised to almost 5% in 2014. such trend is also noticed for other classes also during summer period. similarly, in winter time, in 1991, no such area was found where lst was 20c but in 2014 29% area was found where lst is above 23c. table 5 coefficient variation of temperature in selected time periods season year tmin (°c) tmax (°c) tmean (°c) sd cv (%) ja n u a ry 1991 14.41 20.34 17.24 0.70 4.04 2010 16.72 22.98 19.97 0.82 4.11 2014 20.17 27.30 23.39 1.01 4.33 a p ri l 1991 23.99 34.64 29.67 1.94 6.53 2010 26.83 36.98 31.47 1.67 5.32 2014 25.22 34.60 30.36 1.64 5.40 o c to b e r 1991 21.66 28.09 23.40 0.79 3.36 2010 22.98 30.58 25.37 1.19 4.70 2014 23.63 33.66 28.70 1.28 4.47 multicriteria land surface temperature (mclst) models as mentioned before, the mclst models have been calculated based on six data layers (factors) which control temperature variation. the lst models calculated from the landsat images and the mclst models have been prepared for the same period of time. such models will help to understand whether mclst models can explain lst variation. models for 1991 the wlc values varied from 2.17 to 8.87 during winter, 1.61 to 8.69 in summer and 1.95 to 8.57in monsoon seasons (fig. 5a, 5b and 5c). in all seasons, higher wlc values were noticed in the main urban land and some parts of peripheral urban areas where urban extension has already proliferated. models for 2010 in 2010, wlc varied from 1.45 to 9.04 in winter, 1.60 to 9.70 in summer and 1.74 to 9.39 in the monsoon or rainy season (fig. 5d, 5e and 5f). in all seasons, the upper limit of wlc was above 9, while they were below 9 in 1991. this does indicate that lst has raised between 2010 and 2014. the lst trend extracted from multicriteria lst models shows the same pattern as the extracted surface temperature models from landsat images during the respective seasons. on average surface, the temperature increased with 2.5c in 2010 compared to 1991. models for 2014 in 2014, wlc varies from 1.26 to 9.41 in winter, 2.24 to 9.14 in summer, and 2.54 to 9.35 in rainy season (fig. 5g, 5h, 5i). wlc values at the lower end had raised to some extent indicating rise of lst in the relatively low temperature zones. at the same time, the upper limit of wlc values was also consistently high in all seasons pointing out high lst. from the landsat based lst models, it was clear that, except in pre-monsoon time, the temperature raised by 3 to 3.5c in comparison to 2010. mainly, growing urban intensity could explain this trend. spatial association between lst and mclst models spatial correlation analysis is carried out between the models for the respective periods to bring out the fact that these models are spatially associated. in all seasons and selected seasons, correlation coefficient values vary from 0.44 to 0.81 (table 6) and all values are significant at 99% confidence level. therefore, these models can be considered as spatially associated. moreover, the scholarly works carried out by kawashima et al. (2000) clearly indicates that the mean air temperature is 7 to 9.6c higher than surface temperature. if same line of thinking could be followed, such association is existing. for further analysis of the relationship, the correlation is also calculated between the two models based on different landuse/landcover classes. in summer period, this correlation coefficient is very high (0.93) in case of built up land, -0.57 in vegetated land, and -0.52 in case of moist land and water bodies. in the core area, fig. 4 a) changing pattern of heat zone (intensity) during april; b) during january in 1991 and 2014 22 ziaul and pal (2016) this relation is very strong in most of the periods (r= 0.860.93) while in the peripheral area, the relation is quite weak and varying due to significant differences in landuse/landcover types. in most cases, the strength of the relationship increases over time. even in the peripheral land, the intensity of temperature rise is mentionable. table 6 degree of correlation between actual and potential temperature models (every correlation coefficient has a significance level of 99%) time pre-monsoon monsoon winter 1991 0.68 0.62 0.51 2010 0.75 0.81 0.60 2014 0.44 0.69 0.68 the mclst models do not directly provide an absolute lst value but the relative temperature differences can be explored. relative patterns of wlc values do indicate relative rise or fall of lst. if some random field recording of temperature is made for different sites within the study area and tallying with wlc values, such qualitative mclst models can be quantified. factorial analysis from the selected driving factors of temperature in local scale, it was identified that ndbi most strongly affects the surface temperature followed by land use and major roads. the correlation value between ndbi and lst ranges from 0.42 to 0.80 and mean value for all seasons is 0.66 (table7). densely settled building with very narrow inter buildings spacing, high rise building, expanding roads etc. are some triggering vectors behind the trend of rising temperatures in the urban area. decreasing canopy cover and increasing concrete impervious surface modifies thermal processes in urban regions, thus causing 2 fig. 5 multicriteria lst models a) january 1991 b) april 1991 c) october 1991, d) january 2010 e) april 2010 f) october 2010 g) january 2014 h) april 2014 i) october 2014 based on driving factors image based surface temperature extraction and trend detection in an urban area … 23 3.5c higher temperatures compared to rural areas and this effect is known as urban heat island effect (ogashawara and bastos, 2012). dense mango orchard in the north western part of the study area recorded relatively low lst. but the lst condition is not fixed over time, it also increases. this condition results in confusion regarding the role of local driving factor behind temperature changes. alteration of the hydrologic cycle represents the most significant urban water quality issue at hand today (debusk et al., 2010) because storm water runoff from impervious surfaces creates water quality problems including higher water temperatures and elevated levels of contaminants in surface waters (davis et al., 2010). this effect can immediately influence the nearby chatra wetland which is considered as kidney of the town (kar and pal, 2012). lack of impoundments within the town accelerates rain water to run down with a fast rate and it also causes rise of lst even in the monsoon season. low recharge due to high impervious land reduces moisture availability in pore space of the top and sub soil. so, when incident sun rays strike on surface, they penetrate much deeper into the part of the soil strata and enhance surface temperature. the impact of ndvi is prominent during the pre monsoon season but its impact is less obvious during the monsoon because monotonization of surface in regard to high moisture availability. major roads, specifically the crowded nh34, enhance temperature levels along their axis and their influence is clearly visible in both the landsat image based lst models and mclst models created for different seasons. other roads also influence lst in same trend but not with the same intensity. this sort of result is also found in the work of weng et al. (2004). the modification of lulc associated with urbanization has altered the thermal properties of land, thereby changing the energy budget, creating the uhi as also reported by xiong et al. (2012) in his work. brick kiln factories (15 nos.) in the north western part (bagbari region) of the study area highly increased temperature. actually this layer is not separately taken into consideration because of its identical emissivity with built up area. the impact of water bodies on lowering temperature is reflected by the models. chatra wetland (>4 km2), located at south western part of the study area, not only decreases its own temperature but also helps to reduce the temperature of its surroundings. the turbidity level of this wetland has been rising over time and as a result, even in the wetland domain the temperature has also raised up. related to this, it could be mentioned that in last 20 years more than 50% of the total wetland area has been converted or will be converted into built up land (kar and pal, 2012). therefore, these areas will also show an increased temperature in the future. the railway station modifies the temperature in anisolated manner, mainly in the station premises. all the discussion imparts to the models prepared from landsat images and multi criteria approaches and therefore these are comparable. conclusions it can be said that surface temperature is rising over time in all seasons and the intensification of concrete surfaces within the urban environment and urban expansion in its peripheral zones increases temperature. both types of lst models point out the unidirectionality of the temperature change. land use change in terms of installing brick kiln industries, transforming of wetland into urban land, exchange of land between mango orchard and agricultural land etc. are some prime causes for surface temperature change in the urban fringe area. expansion of concrete surfaces, intensification of built up land, high rise building etc. are some reasons behind increasing temperature in the urban heart land. considering this trend, immediately land transformation policies should be reviewed specially regarding transforming mango orchard and wetland into built up land. wetland and forest land can mediate temperature condition in their surroundings. urbanization is the main driving process of land cover changes and consequently of change oflst. however, unless undertaking a radical urban decentralization policy, it is difficult to stop or reverse the urbanization process even to the medium and small cities because their function as facility hub. vegetation management policies (e.g., green belt) can be implemented that would contain making space for green belts, can consequently help reducing the uhi effect. in addition, policies must not be limited to horizontal growth management only. additional consideration to implement new urbanism (e.g., green building) concepts in the planning permission (or development assessment) stage of development would also help reducing the lst. english bazaar municipality, a small town is so congested in its core part, it is quite difficult make more space available for greening and reducing land surface temperature, table 7 average and range of degree of correlation between lst and selected factors in different seasons parameters range of winter season average of winter season range of premonsoon average of pre monsoon range of monsoon average of monsoon landuse 0.06-0.59 0.38 0.22-0.41 0.32 0.07-0.07 0.07 ndbi 0.61-0.68 0.65 0.42-0.80 0.67 0.62-0.74 0.66 ndvi 0.07-0.17 0.12 0.25-0.65 0.41 0.23-0.41 0.29 ndwi 0.050.37 0.17 0.16-0.48 0.31 0.16-0.27 0.24 major road 0.17-0.27 0.22 0.26-0.30 0.27 0.39-0.44 0.42 railway station 0.04-0.13 0.07 0.07-0.21 0.11 0.13-0.38 0.27 24 ziaul and pal (2016) but further growth should be happening using the new urbanism concepts. existing roof area can be surfaced with horticulture based plants. at present, municipal rules regarding keeping space between two buildings is only 1 foot but this is too narrow. so, this inter building space policy should be reconsidered. one of the valuable environmental limbs is chatra wetland 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sensing study of guangzhou, south china. remote sens. 4, 2033–2056. doi: 10.3390/rs4072033 yuan, f., bauer, m. e. 2007. comparison of impervious surface area and normalized difference vegetation index as indicators of surface heat island effects in landsat imagery. remote sensing of environment 106, 375–386. doi: 10.1016/j.rse.2006.09.003 zha, y., gao, j., ni, s. 2003. use of normalized difference built-up index in automatically mapping urban areas from tm imagery. international journal of remote sensing 24(3), 583–594. doi: 10.1080/01431160304987 zhang, h., qi, z. f., ye, x.y., cai, y. b., ma, w. c. 2013.analysis of land use/land cover change, population shift, and their effects on spatiotemporal patterns of urban heat islands in metropolitan shanghai, china. appl. geogr. 44, 121–133. doi: 10.1016/j.apgeog.2013.07.021 introduction study area materials and methods data and image pre-processing methods lst extraction and modeling methods for framing data layers used for multicriteria lst modeling method for spatial association between landsat based lst model with multicriteria lst (mclst) model results and discussion results extracted from data layers landsat image based lst change multicriteria land surface temperature (mclst) models spatial association between lst and mclst models factorial analysis conclusions references akta4 journal of env. geogr. vol. i. no. 1-2. pp. 31-39 floodplain aggradation caused by the high magnitude flood of 2006 in the lower tisza region, hungary sándor, a.1 – kiss, t.1 1department of physical geography and geoinformatics, university of szeged, h-6722 szeged, egyetem u. 2-6, hungary andrea.sandor@gmail.com, kisstimi@earth.geo.u-szeged.hu abstract the area of floodplains in the carpathian basin was dramatically reduced as a result of river regulation works in the 19th century. therefore, the accumulation processes were limited to the narrower floodplains. the aims of the presented study are to determine the rate of accumulation caused by a single flood event on the active, narrow floodplain of the lower tisza and to evaluate the relations between the aggradation, flow velocity during the peak of the flood and the canopy. the uncultivated lands in the study area cause increased roughness which decreased the velocity of the flood, influencing the rate of aggradation. the highest flow velocity was measured on points where the flood entered to the floodplain and at the foot of the levee. these points were characterised by thick (over 50 mm) and coarse sandy sediment. in the inner parts of the floodplain flood conductivity zones were formed, where the vegetational roughness was small. in the inner parts of the floodplain the rate of aggradation was influenced by the geomorphology and the vegetation density of the area. key words: lower tisza, floodplain, accumulation, flow velocity, roughness introduction the rate of floodplain aggradation is important from the point of view of increasing flood hazard and the dispersion of pollutants during flood events. therefore, the rate of accumulation caused by single floods is studied along several temperate zone rivers (gomez b. et al. 1997, asselmann n. e. m. – middelkoop h. 1998, nagy b. 2002, steiger j. – gurnell a. m. 2002, benedetti m. m. 2003, oroszi v. et al. 2006). the accumulation is affected by several different factors which differ in time and space. the most widely cited and probably the most important factor is the geomorphology of the floodplain (cazanacli d. – smith n. d. 1998, baborowski m. et al. 2007), the roughness of the inundated area (rátky i. – farkas p. 2003, werner m. f. g. et al. 2005) and its land use (knox j. c. 2006). most studies analyse the pattern of the sediment deposited by a single flood event (walling d. e. – he q. 1998, gábris gy. et al. 2002) and its grain-size distribution (hughes d. a. – lewin j. 1982, zhao y. et al. 1999), or the connection between the flow velocity and the deposited sediment (wyzga b. 1999). the flood in 2006 was the highest recorded flood since 1842, when the gauge station network was established along the river tisza (at the study area – mindszent – the former record, 1000 cm in 2000 was replaced by 1062 cm on april 21 2006). in this area recent accumulation processes were studied after the 1998-1999, 2000 and 2001 floods (kiss t. – fejes a. fig. 1 the study area and the location of cross-sections, along them the depth of the fresh sediment, water velocity and the density of vegetation were measured 32 a. sándor – t. kiss joeg i/1-2 2000, kiss t. et al. 2002). the aims of the present study are (1) to determine the accumulation rate caused by an extremely high flood and (2) to study the relationships between aggradation, flow velocity during peak flow and vegetation structure. study area and the 2006 flood the studied floodplain section is located in the lower tisza region (fig. 1), 6.5 km along the river (216.9-210.6 fkm), west of mindszent. here the river tisza has three well-developed meanders; the lowermost is the sharpest. the artificial levees were built in 18901895, creating a narrow floodplain with quite irregular width, as the distance of the levee from the right bank varies between 35 and 560 m, while on the left side it is 110-1100 m respectively. the floodplain is flat, the difference in altitude slightly exceeds 2 m. the lowest features on the floodplain are swales and artificial sandpits and channels, and the higher ones are point bars and natural levees. in the year 2006 two floods were recorded between april 10 and july 5 (fig. 2). the first in april and may was 70-day-long, reaching a new record flood-level (1062 cm), and then a smaller and shorter flood-wave proceeded in june. the first was caused by the rapid snowmelt in the catchment and by the back-drainage of the danube, while the second was due to high precipitation. altogether the floodplain was covered by water for 102 days. fig. 2 recorded water level at the mindszent fluvio-meter in 2006 (data: www.vizadat.hu). the arrow indicates flow velocity measure date methods flow velocity measurements were carried out in order to determine the relation between flood flow and aggradation rate, and to reveal the role of vegetation in affecting flood flow. the number of flow velocity measurements were limited, as it had to be made within one day (april 30, 2006 at 1018 cm, just after the peak of the flood), because of the rapid falling. a calibrated russian flow velocity meter (gr-21) was used from a motor boat, which was anchored. the measurements were made just on the left bank, along 12 cross-sections at 87 points. the exact location of each measurement-point was determined by garmin gps. only at one point we measured the flow velocity at different depths to reveal the role of bushes in reducing flow. however, at each point we made only one measurement at the depth of 90 cm, partly because we wanted to make as many measurements as possible all over the floodplain, and partly because we could not hold it vertically in greater depth. the depth of the water column over the floodplain was 4.7 m in average (max. 5.2 m, min. 2.9 m). at late summer the depth of the fresh sediment was measured along the same cross-sections as of the flow velocity measurements and along new cross-sections at both sides of the river (on ca. 500 points along 31 crosssections). the leaf-layer of last autumn and the artificial surfaces created a reference level, therefore the depth of fresh sediment could be precisely measured. the grainsize distribution was determined by pipetten method and wet sieving. simultaneously with sediment measurements the arboreous vegetation of each point was described, namely species distribution and vegetation density. (vegetation density was defined in different ways; their description can be seen below). in 3.0 x 3.0 m quadrates all the bushes and trees were counted and their periphery was measured at 1.0 m height. this mapping and the aerial photo, made in 2000, were used to create the canopy map of the area, using arcview3.2. software. based on the aerial photo the vegetation patches were identified, and based on the field measurements their average vegetation density was calculated. trees and bushes cover the largest proportion of the area (74.1%), and they play the most important role in increasing the roughness; therefore, these areas were classified from the point of view of flood conductivity. at first the quadrates were classified (table 1) based on indices reflecting the number and size of trees. the density index was defined as the number of trees and bushes in the quadrate; the periphery index is the total sum of the periphery of the timber. in the final classification (table 2) the above-mentioned two indices were summed (canopy index), but the density index was accentuated as according to our field observations it influences the flow velocity more. in the quadrates belonging to the "sparse vegetation" class some old trees or in case of young planted forest no more than 10 trees grow, the underwood is sparse or missing. in the "dense vegetation" class at least 15 trees grow in a quadrate. these forests are undisturbed natural forests, planted poplar stands with sparse underwood. the "medium dense vegetation" category joeg i/1-2 floodplain aggradation caused by the high magnitude flood of 2006 in the lower tisza region, hungary 33 includes disturbed natural forests, poplar stands (at least 45 tree/bush per quadrate) and lands where amorpha bushes appear. the "very dense vegetation" means all those areas (forests, former orchards and plough fields) which are overgrown by dense amorpha bushes. most of the study area (67%) belongs to the category of medium and very dense vegetation classes. table 1 classes based on density and periphery indices density index number of timber 10 >45 9 41-45 8 36-40 7 31-35 6 26-30 5 21-25 4 16-20 3 11-15 2 6-10 1 1-5 periphery index sum of periphery (cm) 5 >160 4 120-160 3 80-120 2 40-80 1 <40 table 2 vegetation classes based on the canopy index vegetation class density index total periphery index canopy index number of quadrates sparse 1-2 1-2 2-4 13 dense 3-4 1-3 4-6 6 medium dense 3-7 1-4 6-9 22 very dense 6-10 1-54 10-15 21 vegetation classes were then converted into roughness categories (table 3) in order to determinate the mean vegetational roughness of the floodplain, following the roughness categories of manning (chow v. t. 1959). however, these categories might vary by the level of the flood: during smaller floods the trunk of trees and bushes submerged increasing the roughness, but as the waterdepth increases, free flood flow might occur over the dense bushes (chow v. t. 1959, németh e. 1959). besides, the roughness changes within the same forest, as it is smaller on roads but greater on the boundaries. table 3 roughness categories (after chow v. t. 1959) category type of vegetation/land use mean roughness (n) 1 river channel 0.03 2 short grass, dirty road 0.03 3 cultivated plough-field 0.035 4 cultivated orchard, uncultivated plough-field, clearings 0.05 5 inundated shallow depressions (sand-pit, scour channel etc.) 0.05 6 uncultivated orchard 0.07 7 forest with sparse underwood 0.12 8 dense forest dense amorpha bushes 0.2 results vegetation of the study area in 2006 the largest proportion of the study area (74.1%) is covered by arbours: most of the forests (67.4%) have natural underwood and only 5.7% has a cleared ground without underwood. however, the land use of the floodplain differs at the two banks of the river: the right side is almost totally covered by forest (willow, poplar and the invasive amorpha fruticosa); but the left side is close to the town, therefore, cultivated areas (orchards 10% and plough fields 10.8%) also appear. however, after the great flood in 2006 many of the orchards and plough fields remained uncultivated (4.7% and 8.8%, respectively). on fields, which remained fallow land for few years (4.9%) invasive species (amorpha fruticosa, echinocystis lobata) create almost impenetrable stands. the roughness (n) of the study area is between 0.03 and 0.2, the mean roughness is 0.13, which is considerably high, falling into the category of "forest with sparse underwood". over half of the territory (60%) is covered by the two highest roughness categories (fig. 3), and less than 10 % is under 0.035. flow velocity changes at the floodplain due to the limited number of velocity measurements, no velocity distribution map of the floodplain was made. the cross-sections will be presented, which are grouped based on the velocity distribution along them. some has the highest flow velocity in the middle of the cross-section, while others have higher flow velocities at their ends. the first group contains such cross-sections (ml-2, ml-5, m l-8 and m l-13), where high flow velocity was 34 a. sándor – t. kiss joeg i/1-2 measured at the middle of the cross-section. their length varies between 200 and 1080 m (table 4). the most characteristic is the m l-13 cross-section (fig. 4), which is located in the inner bend of the lowermost meander. at the foot of the levee, covered by grass (n=0.03), high flow velocity (0.6 m/s) was measured, but in the planted poplar stand with dense underwood (n=0.2) the flow velocity reduced remarkably (0.15 m/s). in the inner part of the cross-section higher velocities were measured over a road (0.32 m/s) and on the boundary between the bushes and the plough field (0.46 m/s). over the immerged dense bushes no movement was detectable under the depth of 90 cm (at the level and below the top of the bushes), therefore, we made more measurements at this point to find out the vertical velocity distribution (fig. 5). flow velocity was above 0 m/s only over the immerged bushes: the highest velocity was measured at the surface (at 10 cm 0.13 m/s), then it decreased to 0 m/s at the depth of 70 cm. this information suggests that in very dense amorpha stands (n=0.2) the roughness is so high that it prevents the waterflow and thus, it is only possible over the bushes. at the bank (on the point-bar) 0.21 m/s flow velocity was measured. the mean flow velocity of the cross-section was 0.18 m/s. the phenomenon, that relatively high flow velocity is typical in the middle of the cross-section, is in connection with flood conductivity routes. in these cases longitudinal patches with low vegetation roughness (road or forest clearings) or deeper swales between two former pointbars enabled faster flow (table 5). fig. 3 vegetation patches classified by their roughness (n) table 4 data of cross-sections with high flow velocity in the middle flow velocity (m/s) crosssection length (m) number of measurement points min. mean max. roughness (n) m l-2 200 6 0 0.17 0.37 n=0.03-0.2 m l-5 650 11 0 0.15 0.62 n=0.03-0.2 m l-8 350 5 0 0.23 0.36 n=0.03-0.2 m l-13 1080 13 0 0.18 0.6 n=0.03-0.2 table 5 characteristics of the points situated in the middle of cross-sections and characterised by high flow velocity crosssection description of the point distance from the river (m) flow velocity (m/s) m l-2 road parallel to the river 55 0.37 m l-5 low-lying surface, swale 305 0.37 m l-8 in clearings parallel to the river 103 0.36 m l-13 road parallel to the river (2 points) 335 and 667 0.46 and 0.32 fig. 4 flow velocity distribution of the cross-section m l-13 (the vegetation type and the roughness are also indicated) the second group of cross-sections is characterised by low flow velocity at their middle zones (m l-3, m l-6, m l-7, m l-9, m l-10 and m l-11). their length varies between 330 and 630 cm (table 6). the cross-section m l-6 is very typical for this group (fig 6). its length is 550 m, and the greatest flow velocity (0.56 m/s) was measured at the grass-covered levee (n=0.03). in the middle of the cross-section the roughness is higher (n=0.05-0.2), therefore, the flow velocity decreased to 0.12-0.2 m/s. near the riverbank, in an old undisturbed gallery forest the flow velocity increased (0.53 m/s). the mean flow velocity of the cross-section is 0.22 m/s. in this crosssection group high flow velocity was typical at the river bank, partly because the morphological situation of the joeg i/1-2 floodplain aggradation caused by the high magnitude flood of 2006 in the lower tisza region, hungary 35 point (at inflexion and at convex bank, where the flood entered to the floodplain), and partly because the smaller roughness in forest with limited underwood or over the road running at the riverbank. fig. 5 vertical velocity distribution over dense bush, at a point 225 m far from the channel one longitudinal section (length: 680 m) was also made in the lowest and sharpest meander, between its inflexion points (fig. 7). at the upper inflexion point, where the flood entered to the floodplain (forest clearance), the greatest flow velocity (0.55 m/s) of the section was measured. as the distance increased from the bank, the flow velocity decreased. along the section the roughness was almost the same (n=0.03) as it was used as ploughland. however, on the edge of the ploughland and a forest (n=0.12-0.2) smaller flow velocity was measured. at the end of the section, at the riverbank flow velocity was again higher (0.37 m/s), though not as great as at the upper inflexion point. the mean flow velocity of this longitudinal section is 0.34 m/s, much higher than any of the cross-sections, showing the existence of a flood conductivity zone. table 6 data of cross-sections with low flow velocity in the middle flow velocity (m/s) crosssection lenght( m) number of sampling points min. mean max. roughness (n) m l-3 630 9 0 0.22 0.28 n=0.03-0.2 m l-6 550 7 0.12 0.22 0.56 n=0.03-0.2 m l-7 415 6 0.1 0.17 0.3 n=0.03-0.2 m l-9 360 5 0 0.15 0.27 n=0.03-0.2 m l-10 320 6 0.07 0.27 0.4 n=0.03-0.2 m l-11 560 8 0.5 0.3 0.68 n=0.03-0.2 fig. 6 flow velocity distribution of the cross-section m l-6 (vegetation type and roughness are also indicated) fig. 7 flow velocity distribution of the longitudinal section (vegetation type and roughness are also indicated) based on the results above, it can be stated that the greatest flow velocity on the floodplain is typical on patches running parallel to the river with low vegetational roughness, i.e. at the grassy levee, at roads and in poplar plantations with limited underwood. however, in areas invaded by amorpha bushes the flow velocity drastically decreases, only over the bushes could the flood waterflow. geomorphology of the riverbed determines where the flood can enter the floodplain, but in this case again the vegetation influences its efficiency. morphology of the floodplain is also important as in the 36 a. sándor – t. kiss joeg i/1-2 deeper swales, as well depending on vegetation conditions, greater flow velocity is typical. aggradation caused by the 2006 flood the depth of deposited sediment was the greatest (50-500 mm) within 10-50 m from the channel. on the left side of the river, where the floodplain is narrow, the amount of aggraded sediment exponentially decreased with distance from the channel (fig. 8), in accordance with earlier research (walling d. e. – he q. 1998). however, the left part of the floodplain is wider, therefore, the pattern of deposition was different, because other factors (geomorphology and vegetation) also influenced the aggradation. for example, we found patches with low aggradation rate. these areas were covered by very dense amorpha bushes which acted as a barrier for the flowing water. therefore, the water slowed down and even stopped among the bushes; thus, sedimentation took place on the boundary of the patch. the effect of floodplain geomorphology on aggradation was obvious where the floodplain was wide. in these cases thicker sediment was deposited in the deeper areas as in sandpits, swallows and along a scour channel. at the points where the flood entered into the floodplain the aggradation was also greater. the 31 cross-sections were grouped based on their length (table 7). group no. i contains those shorter than 150 m, while wider sections belong to the group no. ii. table 7 major characteristics of the studied cross-sections thickness of the fresh sediment (mm) mean flow velocity (m/s) cross-section group crosssection lenght (m) min. mean max. m l-1 105 0.5 34.21 125 mr-3 45 0.5 1.45 6 m r-4 60 0.5 22.43 135 m r-5 60 0.5 10.76 70 m r-6 35 0.5 49.91 130 n o .i . s h o rt er t h an 1 5 0 m m r-7 143 0.5 30.81 230 m l-4 710 0.5 9.3 260 m l-11 555 0.5 45.93 150 0.3 m r-1 560 0.5 7.14 48 m r-2 400 0.5 2.98 15 m r-9 220 0.5 13.59 500 m r-10 300 0.5 5.99 186 m r-11 230 0.5 19.25 500 n o .i i/ 1. e x po n en ti al c h an g e o f se d im en ta ti o n m r-12 353 0.5 65.15 250 m l-3 625 0.5 8.11 200 0.22 m l-5 675 0.5 5.45 120 0.15 m l-8 310 0.5 8.77 144 0.15 m l-9 370 0.5 13.82 280 0.15 m l-10 330 0.5 18.04 170 0.27 m l-12 1085 0.5 4.41 35 m l-16 395 0.5 15.59 300 ii ./ 2 a m r-8 200 0.5 47.91 255 m l-6 550 0.5 6.16 140 0.22 m l-14 750 0.5 7.75 80 0.09 m r-13 250 0.5 4.71 90 ii ./ 2 b m r-14 347 0.5 34.44 280 m l-2 200 0.5 27.94 203 0.17 m l-7 410 0.5 5.16 162 0.17 m l-13 1080 0.5 12.61 150 0.18 n o .i i. l o ng er t h an 1 5 0 m n o .i i/ 2. m o re p ea k s o n s ed im en ta ti o n g ra p h ii ./ 2 c m l-15 585 0.5 8.33 20 the no. i. cross-section group includes the shortest ones (6). a typical example of this group is the mr-4 cross-section which is only 58 m in length (fig. 9). the greatest amount of sediment (135 mm) was deposited on the margin of the channel in a forest with very dense underwood. as far as 20 m from the channel the amount of accumulation was only 15 mm (decreased by 89%), and 50 m far it reduced to 3 mm. here the aggradation from the channel towards the levee decreased exponentially (r2=0.9182). group no. ii. consists of cross-sections wider than 150 m (24). it was also divided based on the thickness changes of the sediment, namely whether it changed fig. 8 pattern of aggradation in the study area joeg i/1-2 floodplain aggradation caused by the high magnitude flood of 2006 in the lower tisza region, hungary 37 exponentially (no.ii/1) or it had more peaks (no.ii/2). typical example for the first group is the ml-11 crosssection starting from the upper inflexion point of the lowest meander (fig. 10). here the greatest amount (150 mm) of sediment was deposited within 180 m zone from the channel, in a poplar forest with dense amorpha bushes. at 190 m from the channel the accumulation suddenly decreased (30 mm) at the border between a plough field and a dense scrub. grain size distribution also changed, as on the banks the sediment consisted 95% sand, but at 190 m from the channel it was only 67%. towards the levee thickness of the fresh deposit decreased and became finer. fig. 9 aggradation along the cross-section mr-4 in some cross sections (no. ii/2b) the maximum aggradation was measured at the channel and somewhere in the mid-zone of the cross-section. an example is the mr-7 cross-section where 230 mm sediment was deposited on the bank (fig. 12), but in 10 m it decreased to 180 mm, and in 25 m far it decreased further to 22 mm. from this point, increasing amount of sediment was measured (max. 60 mm) towards the levee. fig. 10 aggradation along the cross-section ml-11 and the grain size distribution of sediment in case of some cross-sections (i.e. no. ii/2) more peaks appeared on the aggradation graphs. in some of them (no. ii/2a) the greatest accumulation was measured at the bank and near the levee. one of them is the ml-3 cross-section, where at the bank 200 mm thick sediment was deposited, but already at 40 m from the bank the sedimentation decreased to 38 mm, and at 150 m only to 6 mm, respectively (fig. 11). in the middle part of the cross-section only very thin (less than 1 mm) sediment was deposited on a plough field. near the levee (490 m far from the river) again thicker, 3-10 mm sediment accumulated in the deeper lying sand-pits. fig. 11 aggradation along the cross-section ml-3 fig. 12 aggradation along the cross-section mr-7 fig. 13 aggradation along the cross-section ml -13 and the grain size distribution of sediment altogether four such cross-sections exist (no. ii/2c) where three aggradation peaks were detected. for example, in the ml-13 cross-section the accumulation rate decreased exponentially (from 150 mm to 8 mm) in 200 m from the bank (fig. 13), and the sediment became finer. in the middle of the section (ca. 580-680 m from 38 a. sándor – t. kiss joeg i/1-2 the channel) the amount of sediment increased (9-15 mm) and became coarser. the third sediment peak (3-7 mm) was measured in the sand-pit, near the levee, 9501010 m far from the river. it suggests the existence of a flood conductivity zone; this fact, nevertheless, is also supported by the geomorphology (swale). based on the results listed above, it could be stated that the primary factor influencing the aggradation on the floodplain is the distance from the channel (fig. 14). the greatest depth of sediment is deposited in form of pointbars and levees. from the banks the accumulation exponentially decreases towards the levees. the next factor is the pattern of the channel, as (1) where the water enters to the floodplain the aggradation is much higher compared to the neighbourhood, and (2) in case of the sharper bend the floodplain plays important role in flood conductivity, and therefore, in the flood conductivity zone more sediment was deposited. fig. 14 distance from the channel is plotted against the rate of accumulation in case of different roughness geomorphology belongs to the local factors influencing the rate of aggradation, as in deeper areas (e.g. swale, scour-channel and sand-pit) the accumulation is always greater. far from the channel vegetation plays the most important role in the process of sedimentation. here the very thick bushes prohibit the waterflow, thus the aggradation is smaller (less than 1 mm) than in areas at similar location (similar distance from the channel and similar geomorphological situation). due to the abovementioned local factors the exponential function can be applied only where the floodplain is narrow (max. 150 m). the grain-size distribution of the sediment changes, as the sediment becomes finer departing from the channel. however, in flood conductivity zones coarser material was found in accordance with the flow velocity. the coarsest material is deposited in the area of natural levees and point bars. conclusion the present land use of the area causes increased vegetational roughness (mean n=0.13), as 74% of the study area is covered by forest with dense underwood, uncultivated orchards and ploughlands. increased roughness highly influences the waterflow: the denser the vegetation is the slower the waterflow on the floodplain becomes. the highest flow velocity is typical at those points where the flood enters the floodplain and at the foot of the levee. on the floodplain, where the roughness is small and therefore flow velocity is high, flood conductivity zones are formed running parallel with the river. the rate of aggradation is primarily determined by the distance from the channel. the thickest (over 50 mm) and coarsest (95% of sand) sediment is deposited within 10-50 m from the channel, in the zone of point-bars and natural levees, independent of vegetation. the sediment became finer and the rate of aggradation decreased with the distance from the channel. in the flood conductivity zones, which run parallel with the channel and where the vegetation is sparse, thicker and coarser sediment was deposited. in the narrow floodplain sections the rate of aggradation fits the exponential curve (r2=0.8-0.9) as it was described in previous studies. however, where the floodplain is wider than 150 m, the aggradation is influenced by not only the distance from the channel, but also by the geomorphology of the area and the density of vegetation. the pattern of fresh sediment follows the channel; however, in the southern sharp bend the flood makes a "short-cut", as it was reflected not only by higher flow velocity but also by greater aggradation. patches characterised by small aggradation develops under very dense vegetation, where the flow velocity decreased to zero. it means that the very dense vegetation acts as a barrier against waterflow, therefore, sedimentary processes are more pronounced on their edges and much less sediment is deposited within. comparing these results with earlier measurements made in the same study site along the same crosssections (kiss t. – fejes a. 2000, kiss t. et al. 2002), we can state that the pattern of aggradation was very similar in each year. the rate of aggradation slightly differed, as in 2000 the mean accumulation on the floodplain was 20.5 mm (kiss t. et al. 2002) and now it was 18.9 mm. acknowledgements the work was financially supported by the otka 62200 research grant. references asselmann n. e. m. – middelkoop h. 1998. temporal variability of contemporary floodplain sedimentation in the joeg i/1-2 floodplain aggradation caused by the high magnitude flood of 2006 in the lower tisza region, hungary 39 rhine–meuse delta, the netherlands. earth surface processes and landforms 23: 595-609 baborowski m. – büttner o. – morgenstern p. – krüger f. – lobe i. – rupp h. – tümpling w. v. 2007. spatial and temporal variability of sediment deposition on artificial-lown traps in a floodplain of the river elbe. elvironmental pollution 148: 770-778 benedetti m. m. 2003. controls on overbank deposition in the upper mississippi river. geomorphology 56: 271-290 cazanacli d. – smith n. d. 1998. a study of morfology and texture of natural levee – cumberland marshes, saskatchewan, canada. geomorphology 25: 43-55 chow v. t. 1959. open channel hydraulics. new york: mcgraw-hill. 89-127 gábris gy. – telbisz t. – nagy b. – belardinelli e. 2002. a tiszai hullámtér feltöltıdésének kérdése és az üledékképzıdés geomorfológiai alapjai. vízügyi közlemények 84: 305-322 gomez b. – phillips j. d. – magilligan f. j. – james l. a. 1997. floodplain sedimentation and sensitivity: summer 1993 flood, upper mississippi river valley. earth surface processes and landforms 22: 923-936 hughes d.a. – lewin j. 1982. a small-scale floodplain. sedimentology 29: 891-895 kiss t. – fejes a. 2000. flood caused sedimentation on the foreshore of the tiver tisza. acta geographica szegediensis 37: 51-55 kiss t. – sipos gy. – fiala k. 2002. recens üledékfelhalmozódás sebességének vizsgálata az alsó-tiszán. vízügyi közlemények 84/3: 456-472 knox j. c. 2006. floodplain sedimentation in the upper mississippi valley: natural versus human accelerated. geomorphology 79: 286-310 nagy b. 2002. a felsı-tiszai árvizek kialakulásának tényezıi, különös tekintettel az utóbbi évek katasztrófáira, illetve azok elhárításának lehetıségeire. beregszász [beregovo, ukraine]: manuscript. 40-47 németh e. 1959. hidrológia és hidrometria. budapest: tankönyvkiadó. 161-210 oroszi v. gy. – kiss t. – botlik a. 2006. a 2005. évi tavaszi áradás üledékfelhalmozó hatása a maros hullámterén. iii. magyar földrajzi konferencia budapest 2006. szeptember 67. cd-rom. 1-12 rátky i. – farkas p. 2003. a növényzet hatása a hullámtér vízszállító képességére. vízügyi közlemények 85/2: 246-265 steiger j. – gurnell a. m. 2002. spatial hydrogeomorphological influences on sediment and nutrient deposition in riparian zones: observations from the garonne river, france. geomorphology 49: 1-23 walling d. e. – he q. 1998: the spatial variability of overbank sedimentation on river floodplains. geomorphology 24/2-3: 209-223 werner m. g. f. – hunter, n. m. – bares, p. d. 2005. identifiability of distributed floodplain roughness values in flood extent estimation. journal of hydrology 314: 139-157 wyzga b. 1999. estimating mean flow velocity in channel and floodplain areas and its use for explaining the pattern of overbank deposition and floodplain retention. geomorphology 28: 281-297 zhao y. – marriott s. – rogers j. – iwugo k. 1999. a preliminary study of heavy metal distribution on the floodplain of the river severn, u.k. by a single flood event. science of the total environment 243-244: 219-231 journal of environmental geography journal of environmental geography 10 (1–2), 53–59. doi: 10.1515/jengeo-2017-0006 issn: 2060-467x dating the holocene incision of the danube in southern hungary orsolya tóth1, györgy sipos1*, tímea kiss1, tamás bartyik1 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: gysipos@geo.u-szeged.hu research article, received 10 april 2017, accepted 20 june 2017 abstract the alluvial development of the great hungarian plain has greatly been determined by the subsidence of different areas in the pannonian basin. the temporal variation of subsidence rates significantly contributed to the avulsion and shifting of main rivers. this was the case in terms of the hungarian lower danube when occupying its present day n-s directional course. the considerable role of tectonic forcing is also supported by the presence of different floodplain levels. although, several channel forms are identifiable on these the timing of floodplain development has been reconstructed up till now mostly by the means of geomorphological analysis, and hardly any numerical dates were available. the main aim of this study is to provide the first osl dates for palaeo-channels located on the high floodplain surface of the hungarian lower danube, and to determine the maximum age of low and high floodplain separation on the kalocsa plain. for the analysis two meanders were sampled close to the edge of the step slope between the two levels. according to the results, the development of the investigated palaeo-meanders could be rapid. the formation of the older meander was dated to the late atlantic, while the possible separation of the high and low floodplain surfaces could start in the beginning of the subboreal phase. keywords: hungarian lower danube, floodplain development, holocene, osl dating introduction the alluvial development of the great hungarian plain (ghp) has greatly been determined by the selective subsidence of different areas in the pannonian basin. the significance of tectonic control on fluvial processes has been indicated by several earlier research (e.g. somogyi, 1961; borsy, 1992; gábris and nádor, 2007; kiss et al., 2015). the temporal variation of subsidence rates at different areas lead to the time-to-time avulsion and shifting of the main rivers and related tributaries. major shifts however were also influenced by geomorphological processes, namely alluvial fan building and subsequent sliding off the rivers from these elevated surfaces. concerning the danube a significant, but presumably gradual diversion occurred during the late würm period (pécsi, 1959; pécsi, 1991; mezősi, 2011) on its ghp section, when the river had shifted from its earlier nw-se course to a n-s direction by sliding off its alluvial fan, the danube-tisza interfluve (mezősi, 2011). the process can also be explained by the activation of the kalocsa and baja depressions, located near the hungarian-serbian border. according to jaskó and krolopp (1991), this subsidence zone attracted the danube to its present direction at around 30-40 ka, and fault lines related to the zone are still active, though only moderately (mezősi, 2011). obviously, in case a river shifts to a depression, let it be of geomorphic or tectonic origin, incision is generated, which propagates upstream and leads to the development of alluvial fan terraces indicating the major phases of changes (bridge, 2003; schumm, 1979). the age of fluvial forms on the abandoned floodplain (now terrace level) corresponds to the maximum, while that of active floodplain forms to the minimum age of incision. the numerical dating of fluvial forms therefore is crucial to reconstruct the timing of terrace formation and consequently the phases and sometimes even the rate of subsidence (knighton, 1998). the strath terraces of the danube on its hungarian upland section had been intensively studied with classical and more modern dating methods to assess the uplift rate of the adjacent members of the transdanubian mountains (pécsi, 1991; ruszkiczay-rüdiger et al., 2005; gábris, 2013). concerning the downstream ghp section of the river pécsi (1959, 1967) investigated the geomorphological units, terrace materials and development of the floodplain and its levels. he concluded that the northern part of the present ghp floodplain (csepel -solt plain) is older than the southern (kalocsa plain), and that the upper 10-20 m of sediments is almost completely reworked by the lateral movement of the danube. nevertheless, in both areas a low and a high floodplain surface (terrace) can be identified. t he term high floodplain refers to the fact that although this surface lies 1-2 m higher it is still inundated by extreme floods. consequently, pécsi (1967) claims that fluvial deposits on the low and high floodplain cannot be separated in age, though the d evelopment of 54 tóth et al. (2017) the high floodplain can clearly be related to the late pleistocene activation of the baja and kalocsa depressions. so far the timing of floodplain development in the area has been reconstructed mostly by the means of geomorphological analysis, hardly any numerical dates are available concerning the sediments and forms of the high floodplain surface. two radiocarbon dates from subfossil drift woods placed the age of the right bank side high floodplain surface of the danube, just opposite to the kalocsa plain, to cca. 40 000 and 11 000 bp (hertelendi et al., 1991). in terms of late pleistocene and holocen terrace surfaces, where the fluvial forms are still identifiable a straightforward method of dating is using optically stimulated luminescence (osl), which determines the last exposure of sediments to sunlight, i.e. the time of sediment deposition. the method has been extensively applied in studies related to the dating of floodplain surfaces along several rivers (e.g. kiss et al., 2013; olszak et al., 2016; ruszkiczay-rüdiger et al., 2016; meng et al., 2015). by considering the above, the main aim of the present study is to provide the first osl dates for palaeochannels located on the high floodplain surface of the hungarian lower danube, and this way to provide a maximum age to the separation of the low and high floodplain levels on the kalocsa plain. study area and sampling the study area is located on the kalocsa plain, which is situated at the middle section of the hungarian lower danube (fig. 1). the floodplain area is characterised by two floodplain levels: the elevation of the lower floodplain surface (a-level) is between 90 and 92 m asl, while that of the higher floodplain surface (b-level) is between fig. 1 location of the study area, geomorphological setting, and sampling points dating the holocene incision of the danube in southern hungary 55 92 and 94 m asl. eastwards the study area is adjacent to the danube-tisza interfluve covered by sand dunes and characterised by a relief between 96 and 105 m asl. westwards loess plains border the danube plains, with an elevation reaching even 150 m asl (fig. 1). sediment samples were collected from two palaeo-meanders located on the b-level to determine the maximum age of floodplain surface differentiation, and the time of active b-level floodplain development. the two selected palaeo-channels belong to two separate meander systems. based on the geomorphological map (fig. 1), both systems developed through chute cut-offs and consequent meander growth, being characteristic in case of meanders on the lower floodplain as well. in case of the eastern meander (width=170 m, r=1,7 km) one drilling was made (ae1) to sample channel sediments, as point bars were hardly recognisable on the field (fig. 1). at the ae1 drilling point 3 osl samples were collected from 60, 130 and 190 cm (ae1/1, ae1/2, ae1/3). in terms of the western meander (width: 370 m, r=720 m), right on the edge of the b-level, point bars were sampled at three locations (ae2, ae3, ae4), from depths 70, 70 and 110 cm, respectively. osl samples were mostly taken from layers of pure sand, however in terms of ae1 upper two samples were categorised on the field as sandy silt. undisturbed sampling was made with steel cylinders applicable to an eijkelkamp hand drill system. samples weighed approximately 200 g. background samples were also collected from above and from below each osl sample. methods the geomorphological map of the study area was compiled on the basis of 1:10 000 scale topographical maps, with 1 m contour line interval, occasionally supplemented by 0.5 m contour lines, the age of sediment samples was determined by optically stimulated luminescence. samples were either composed of medium sand, or the mixture of fine sand and silt, though containing an adequate amount of medium sand in the latter case as well, thus the so called coarse grain quartz dating procedure was applied. in terms of fluvial samples usually the sand sized quartz fraction is investigated anyway, assuming that it usually has more chance for complete bleaching during sediment transport. the preparation of the samples followed usual laboratory techniques (aitken, 1998; mauz et al., 2002). after removing the samples from the cylinders they were dried and the 90-150 μm fractions was separated by sieving. the carbonate and organic material content was removed by repeated treatment in 10% hcl and 10% h 2o2. a napolytungstanate (lst fastfloat) heavy liquid flotation was applied for the separation of the quartz fraction. this step was followed by a 50 min etching in 40% hf, aiming at removing any remaining feldspar contaminations and the outer layer of quartz. purified quartz grains were adhered to stainless steel discs of 10 mm diameter by silicone spray. for osl a ø6 mm mask for the final measurements ø2 mm mask was applied to control the number of grains on a disc. a number of aliquots were prepared for luminescence tests and for equivalent dose (de) determination. measurements were made using a risoe da-15 tl/osl luminescence reader by applying the single aliquot regeneration (sar) protocol (wintle and murray 2006). a preheat test was used for determining optimal heating parameters during the sar measurements. preheat temperatures were varied between 180 oc and 300 oc. during the tests 1) sar recycling ratios (ratio of two sensitivity corrected luminescence signals generated by identical regeneration doses) ; 2) recuperation (thermal and photo transfer of electrons to osl traps); and 3) dose recovery (ratios recycling ratio being within 1.00 ± 0.05, de error being lower than 10%, recuperation being lower than 5%) were monitored to determine the best thermal treatment. a combined preheat and dose recovery test was performed. preheat temperature was increased 200 °c sar measurements were performed on 48–144 aliquots, depending on the proportion of acceptable measuremets. acceptability was assessed using the standard rejection criteria for each aliquot. thresholds of rejection were the following: recycling ratio being within 1.00 ± 0.05, de error being lower than 10%, recuperation being lower than 5%. possible feldspar contamination was also monitored by measuring irsl/osl depletion ratio at the end of the sar procedure. the first 0.5 s of osl curves was taken as the signal, the last 10 s as the background of measurements. sample de was calculated from aliquot de using either the minimum age model (mam) (ae1/1, ae1/2), or the central age model (cam) (ae1/3, ae2, ae3, ae4) depending on the dispersion de values (galbraight et. al 1999). environmental dose rate (d*) was determined by using high-resolution, extended range gamma spectrometry (canberra xtra coaxial ge detector), using 500 cm3 marinelli beakers. dry dose rates were calculated using the conversion factors of adamiec and aitken (1998). wet dose rates were assessed on the basis of in situ water co ntents. the rate of cosmic radiation was determined by considering burial depth following the method of prescott and hutton (1994). results and discussion during the evaluation, a major problem was the low luminescence signal intensity and the low sensitivity of the samples (fig. 2). consequently, numerous aliquots did not pass the necessary criteria and were finally rejected from de calculation. therefore, a high number of aliquots were measured finally to get an adequate amount of results for the statistical analysis 56 tóth et al. (2017) of equivalent doses. in average 30-40% of the aliquots turned to be acceptable for sample de assessment (table 1). in case of preheat tests the problem of low sensitivity was a less significant issue, as due to the higher number of grains (ø6 mm mask ) on the measurement discs luminescence response was considerably higher. the most appropriate preheat temperature for all samples was 200 °c for the sar measurements (fig. 3), since the dose recovery ratio at this temperature was well within the limits of acceptability. nevertheless, the spread of the recycling ratios was wider in some cases and recuperation was over 5 % in case of samples ae1/2 and ae4. consequently, the final sar measurements were carried out with using a hot bleach treatment, i.e. inserting a high temperature (280°c) optical bleaching at the end of each measurement cycle. by the application of the right temperature treatment the samples performed adequately to retrieve reliable results and ages. regarding drilling point ae1 the sampled sand layers at 70, 130 and 190 cm depth were dated to 6.7±0.6 ka, 7.2±0.4 ka and 6.1±0.5 ka, respectively. the lowermost sand layer (ae1/3) was characterised almost exclusively by medium sand, and the distribution of individual de results showed a central tendency (fig. 4), consequently, it is suggested that this sample had undergone the most complete resetting process during transportation and sedimentation. therefore, both from a sedimentological, and fig. 2 figures a and b show an appropriate shine-down curve (a) and dose response curve (b), meanwhile c and d figures represent the low intensity table 1 dose rate, equivalent dose and age data of the investigated samples sample aliquots (used/measured) depth (m) moisture content (%) u (ppm) th (ppm) k (%) d* (gy/ka) de (gy) age (ka) ae1/1 30/72 0.6 13±1.3 2.95±0.02 5.05±0.06 1.38±0.04 2.80±0.08 20.27±0.82 6.7±0.6 ae1/2 27/48 1.3 21±2.1 2.86±0.04 5.59±0.07 1.36±0.04 2.46±0.07 24.79±0.86 7.2±0.4 ae1/3 25/96 1.9 33±2 2.76±0.03 6.13±0.07 1.34±0.04 2.37±0.07 18.49±1.61 6.1±0. 5 ae2 26/72 0.7 16±2 2.87±0.02 4.53±0.06 1.22±0.04 2.49±0.07 11.76±0.65 4.7±0.3 ae3 35/64 0.7 7±2 1.80±0.02 3.63±0.04 1.13±0.03 2.27±0.07 11.05±0.5 4.9±0.3 ae4 58/144 1.1 7±2 2.22±0.02 3.68±0.04 1.18±0.03 2.55±0.08 12.87±1.07 5.0±0.5 dating the holocene incision of the danube in southern hungary 57 from an osl point of view this sample can represent the time of major fluvial activity. this is in correspondence with the major findings of tóth et al. (in press), who measured almost complete resetting in terms of modern coarse grain sediments along the present day danube. in the meantime the upper two samples yielded somewhat higher ages than ae1/3, which can be explained by their different sedimentology, i.e. the high proportion of fines, which refers to a post formational, lower energy deposition, being less favourable in terms of osl signal resetting and leading to possible age overestimation. based on the results, in case of sample ae1/2, characterised by the finest grain size, the age could be overestimated by more than 1 ka, while in case of the coarser ae1/1 by more than 0.6 ka (fig. 5). the ages of samples ae2, ae3 and ae4 were very similar and stayed within error, ae4: 4.7±0.3 ka, ae6: 4.9±0.3 ka, ae7: 5.0±0.5 ka (table 1). as the formation age of point bars cannot be separated, results refer to a relatively fast meander development between 4.7 and 5.0 ka, reflecting the dynamic nature of danube fluvial activity. based on the first age results from the area, the danube was actively forming its present day high floodplain up till 5 ka. consequently, the maximum age of incision and the development of the present day floodplain can be placed to the beginning of the subboreal phase. however, in order to question or reinforce the morphological interpretation of pécsi (1967), i.e. the formation time of the higher and lower floodplain levels are hard to separate, needs further investigation in the area, especially focusing on lower floodplain palaeochannels. nevertheless, the osl dates presented here give a framework for further studies, and also imply that if there is a separation time between the two levels, it must be in the second half of the holocene. fig. 3 preheat and dose recovery tests of the samples. the red line and the dashed line mark the three criteria and the errors of the criteria fig. 4 dose distribution of individual de of ae1/2 (a) and ae1/3 (b). in case of ae1/2 mam, meanwhile in case of ae1/3 cam was used for the calculations 58 tóth et al. (2017) conclusions floodplain development along the hungarian lower danube has previously been reconstructed mainly on the basis of geomorphological evidence. the present study has provided the first osl dates concerning the fluvial forms of the high floodplain surface on the kalocsa plain and therefore on the entire ghp section of the river. the osl sensitivity of the sampled sediments is low, therefore a high number of measurements is needed to get the necessary amount of results for the reliable statistical analysis of equivalent doses. however, by the application of the right temperature treatment the samples performed adequately to retrieve reliable results and ages. the development of the investigated palaeomeanders could be rapid. in case of the older meander the age of channel forming fluvial activity can be inferred from the lowermost sample, yielding a 6.1±0.5 ka age placing the development of the meander to the late atlantic phase. in terms of the younger meander, on the edge of the high floodplain the ages of consecutive pointbars were in the range of 4.7±0.3 ka and 5.0±0.5 ka, meaning, that the separation of the high and low surfaces could start in the beginning of the subboreal phase or later. acknowledgements the research was funded by projects nkfi k 119309, nkfi k 119193 and huro/1101/126 enviarch references adamiec, g., aitken, m. 1998. dose-rate conversion factors: update. ancient tl 16 (2), 37–50. aitken, m. j. 1998. an introduction to optical dating. oxford university press. london. borsy, z. 1992. általános természetföldrajz. nemzeti tankönyvkiadó, budapest. 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(in hungarian) schumm, s. a. 1979: geomorphic thresholds: the concept and its applications. transactions of the institute of british geographers 4, 485–515. doi: 10.2307/622211 tóth, o., sipos, gy., kiss, t., bartyik, t.,: variation of osl residual doeses in terms of coarse amd fine grain modern sediments along the hungarian section of the danube. geochronometria (in press) wintle, a. g., murray, a. s. 2006. a review of quartz optically stimulated luminescence characteristic and their relevance in singlealiquot regeneration dating protocols. radiation measurement 41, 369–391. doi: 10.1016/j.radmeas.2005.11.001 journal of environmental geography 5 (1–2), 21–28. aeolian surface transformations on the alluvial fan of the nyírség józsef lóki * , gábor négyesi, botond buró, enikő félegyházi department of physical geography and geoinformatics, university of debrecen, egyetem tér 1, h-4010 debrecen, hungary *corresponding author, e-mail: loki.jozsef@science.unideb.hu abstract the evolution of the nyírség and its landforms has been widely addressed by hungarian geographers and geologists in the past and at present as well. early works were mainly concentrating on understanding the complex, fluvial and aeolian genetics of the territory, later more specific forms and problems were studied and revealed. by the increasing number of chronological evidence derived from stratigraphic, pollen and archaeological data and absolute dating techniques (radiocarbon and optically stimulated luminescence) the geomorphological development can be reconstructed in more detail, especially in the context of climate variations and human intervention. our study aims to summarize and outline the times of aeolian activity, with special respect to holocene events, on the basis of the researches carried out so far. by nowadays it is obvious that sand was moving on several occasions in the nyírség during the holocene subsequent to the main aeolian land formation periods of the upper pleniglacial and the late glacial. in the first half of the holocene sand movement can be related to dry periods, thus aeolian activity was driven mostly by climatic factors. in the second half of the holocene the area of land affected by wind erosion decreased and in most cases events can be associated to the activity of man. nevertheless, climatic and anthropogenic factors could be superimposed, leading to significant local sand mobilisation. keywords: wind-blown sand, holocene, climate change, human impact introduction earth scientists have studied the nyírség for over 100 years but geological and geomorphological research can still contribute to the understanding of the surface development of the area. according to nagy (1908), the sand of the nyírség was placed to its current location from the alluvial fans of the ondava, tapoly, laborc, ung and latorca rivers in the foreground of the volcanic mountains, i.e. it was transported by wind from distant areas. cholnoky (1910) in his work entitled “surface of the great hungarian plain” discussed the sand area of the nyírség in detail and explained also the development of the landforms. he thought also that the sand was originated from the “debris” of the ondava-tapoly-ung and latorca and according to him the “strong northern foehn winds formed semi-bond wind-blown sand forms on the loess plateau of the nyírség”. according to these, the wind-blown sand was formed after the formation of the loess. in his opinion the sand of the nyírség came from a long way and this explained the roundedness of the grains. one characteristic of the semi-bond windblown sand is that the forms develop where vegetation cannot protect the surface. therefore it is hard to believe that grains could have been transported for such a long distance along a surface covered partially by vegetation. nevertheless, the idea of the renowned geographer remained for decades influencing other researches as well. the theory of cholnoky became outdated when sümeghy (1944) – based on borehole data – described the nyírség as an alluvial fan built by rivers flowing from the carpathians and transylvania. he also noted that no loess can be found underneath the wind-blown sand but fluvial sand supplying the material blown by winds to form wind-blown sand. his theory was proved by stratigraphic and morphological research as well. aeolian landforms of the nyírség significant differences can be found in the descriptions of the landforms in the nyírség. nagy (1908) considered ripple marks, hummocks and yardangs, as he called dunes dominant. he also wrote that sand moved towards the south in the form of barchans. he noticed that there are significant differences among ripple mark surfaces and that different forms can be found south and north of the watershed in the nyírség. formation of the landforms, however, was explained improperly by him. according to cholnoky (1910), sand dunes are the forms of semi-bond sand characterised by crests elongated according to the orientation of the prevailing wind and by ripple marks in between them. in his opinion westerly winds pushed the middle section of the crests slightly to the east, however, the main direction remained. balla (1954) writes about parabolic blowout dunes, longitudinal dunes, kádár type lybian dunes, ripple marks and coastal dunes. he explains the formation of the coastal dunes by eastern and northeastern winds. in his opinion, sand blown from the beds with low water level was accumulated in the form of dunes along the shores in the dry periods of the würm. kádár (1956) discussed the nyírség as well in his work studying wind-blown sand. in this publication abandoned his earlier theory related to libyan dunes and he termed the parabola dunes elongated along their eastern wing beside inter-dune water as a marginal dune. borsy (1961) carried out detailed geomorphological mapping based on field-research of several years in the nyírség resulting in the first geomorphological map of a hungarian sand area. he studied the size, orientation and internal stratification of the landforms drawing conclusions mailto:loki.jozsef@science.unideb.hu 22 lóki et al. (2012) on the palaeo-wind conditions as well. he systemized and classified the deflation and accumulation forms and described their development in detail. he discussed the areas of the nyírség and their aeolian landforms separately. age of the wind-blown sand layers the first statements related to the age of the wind-blown sand landforms in the nyírség are written in the book of borsy (1961). when studying the surface of the nyírség he assumed holocene sand movements based on the more intact landforms greater in size. he also noticed the fossil soils dividing the dunes, and identified the loess layers as well. he reckoned the formation of the windblown sand above the loess layer took place in the hazel phase when the climate was drier and warmer than today. he changed his views regarding sand movement in the holocene when 14 c age determinations enabled the more accurate calculation of wind-blown sand movement periods (fig. 1). radiocarbon ( 14 c) age data the first results were obtained when the strata of the sand quarry in the western outskirts of aranyosapáti were studied where two wind-blown sand strata of different age are divided by a loess layer (fig. 2). charcoal remnants in the fossil soil developed on the loess made 14 c age determination and thus the more accurate definition of the wind-blown sand movement periods possible. fig. 1 location of boreholes and outcrops in the nyírség and in the marginal areas of the alluvial fan 1:pollen boreholes; 2:radiocarbon; 3:outcrops; 4:boreholes; 5:osl; 6:rivers; 7:settlements; a:nyírség; b:hajdúhát; c:upper-tisza-region aeolian surface transformations on the alluvial fan of the nyírség 23 age of the fossil soil is 12900±500 years bp, i.e. it was formed in the first milder climate of the late glacial. the wind-blown sand below the loess layer was formed before this date from the fluvial sand of the alluvial fan. based on the radiocarbon data obtained from the research carried out in the nyírség, bodrogköz and the danube-tisza interfluve, the first major accumulation of wind-blown sand occurred in the upper pleniglacial and it was followed by several in the dryas (borsy et al., 1981, 1985; lóki et al., 1993). fig. 2 sand quarry in the outskirts of aranyosapáti (1: loess, 2: wind-blown sand) based on the data gained by the research in the 1980s it can be stated that the landforms of hungarian wind-blown sand areas were formed in the dry periods of the late glacial and sand moved only in a limited area primarily due to anthropogenic effects in the holocene. a humus layer at small depth underneath the surface (fig. 3) is traceable in numerous outcrops in the nyírség that is the continuation of the surface soil frequently. several scientists (marosi, 1967; borsy, 1961; borsy and lóki 1982; lóki, 2003) explained the burial of these soils by wind erosion as a result of deforestation in the 18 th century. this correct statement has to be completed by that – on the basis of historical data – deforestations took place in the early 19 th century as well in order to increase the ratio of arable lands, thus wind erosion could have made its influence felt at that time as well. in the course of recent research (lóki et al., 2008) new outcrops were found in which fossil soil divides the wind-blown sand strata. these, however, are thinner (fig. 4) than the soils formed in the late glacial (fig. 5). this suggests shorter period suitable for soil formation. in the subsequent dry period soil moved again. radiocarbon age data of soils prove sand movements in the holocene. age of the fossil soil in the outcrop near gégény is 3740±50 years (bp) and it is covered by 4 m of wind-blown sand. age of the fossil soil in the sand quarry at kántorjánosi is 9300±50 years (bp) and this is also covered by 4 m of wind-blown sand (fig. 6). fig. 3 young fossil soil in a wind-blown sand outcrop in the nyírség fig. 4 position and age of the fossil soil horizon (sand quarry at gégény) fig.5 late glacial soil east of nyíregyháza 24 lóki et al. (2012) fig. 6 position and age of the fossil soil horizon (sand quarry at kántorjánosi) the two soil horizons of different age suggest that sand moved at several times in the holocene and that wet and dry periods alternated. however, outcrops were also found in the nyírség in which no fossil soil was detected in the 4-6 m thick wind-blown sand on top of the fluvial sand (fig. 7). age of these strata was determined by osl measurements fig.7 wind-blown sand outcrop with strata showing different grain-size distribution osl age data in the nyírség in recent years kiss and co-workers carried out osl measurements on samples from the nyírség. these measurements are important because they enable the determination of the age of sand strata without soils as well. their research at study areas near bagamér and erdőspuszta revealed wind erosion during the atlantic and subboreal phases (kiss and sipos, 2006; kiss et al., 2008). sand movement in the atlantic phase in the nyírség was already presumed by borsy (1980), however, at that time measurements were not available to prove that. data were obtained from research in other hungarian wind-blown sand areas in the last decade (ujházi, 2002; ujházi et al., 2003). ujházi (2002) showed upper atlantic sand movement above the older dryas applying luminescence measurements in outcrops at dunavarsány. research carried out in the danube-tisza interfluve (lóki and schweitzer, 2001; nyári et al., 2006; kiss et al., 2008; sipos et al., 2006) verified sand movements at the beginning of the subatlantic phase, in the iron age and at the time of the great migrations as well. all these data indicate that aeolian land formation prevailed at several times in the holocene. stratigraphic and pollen data changes in the stratification of accumulation forms, archaeological findings in the outcrops and alterations of the pollen content of the strata yield more data for making the reconstruction of aeolian surface development more accurate. considering the stratification of the wind-blown sand outcrop near gégény mentioned above it can be stated that the accumulation of the 4 m thick wind-blown sand covering the subboreal fossil soil was followed by another sand movement. succession in the eastern wall of the dune (fig. 8) supports this as sloping strata are covered by almost horizontal wind-blown sand strata. these are made variable by iron pan layers. strata series with different orientations suggest changes in wind directions. the two differing strata series are not divided by a younger soil horizon because the conditions of soil formation were missing on the loose and dry sand surface. fig. 8 strata series with different orientation in the sand quarry at gégény the stratigraphic analysis included the surfaces covered by shroud of sand in the marginal areas of the nyírség and the river beds buried partly by wind-blown sand as well. archaeological findings helped determining the age of sand movement (fig. 9) in the strata of outcrops in the areas covered by shroud of sand (félegyházi and lóki, 2006). aeolian surface transformations on the alluvial fan of the nyírség 25 based on our research so far it can be stated that the sand sheet covers in the southern marginal areas of the nyírség were formed in several periods. sedimentological and palynological analyses verified clearly the accumulation of strata related to shroud of sand at the end of the pleistocene and in the holocene. analysis of the upper pleniglacial selaginella containing bog strata exposed in the outskirts of álmosd and kokad and south of hajdúbagos suggests the settlement of bog pine indicating dry summer. in the periods of drought the grass vegetation bonding the surface on the dunes became dry and the sand started to move. further movement of the sand was impeded only by the swamps and bogs developed in the marginal areas in wetter periods therefore wind spread only little sand onto the bogs and swamps. fig.9 strata series in the borehole drilled near hosszúpályi (a:wind-blown sand, b:findings of sarmatian age, c: findings of bronze age) stratigraphic and palynological analyses of boreholes drilled in the abandoned riverbeds in the alluvial fan of the nyírség contributed to the more accurate reconstruction of its land development. one borehole was drilled in the depression starting from hajdúhadház through újfehértó and nyíregyháza up to the small tisza, while another borehole is located in the bed remnant detectable from nyíradony to rétköz. in the 550m deep borehole drilled in the bed remnant in the vicinity of újfehértó the bottommost sediment that yielded pollen was found in the stratum between 520 and 480 cm (fig. 10). the 20% ratio of floating red-grass and galingale (cyperaceae) among the pollens indicate lacustrine conditions with low stagnating water. the 10% of spikemoss (selaginella) among the pollens indicate clearly the cold, boreal climate of the pleistocene. dry terraines of the area were covered by steppe meadows with pine groves. the pine forests were composed of swiss pine (pinus cembra), scots pine (pinus sylvestris), spruce (picea) that are characteristic for the taiga and have always been rich in the forests of the wetter taiga. wetter climate is also supported by the presence of willow (salix). similar pollen composition was detected in the strata of the fehér lake at kardoskút and in the older strata of the nagymohos bog at kelemér from the interstadial of the upper plenniglacial the of which was determined to be 26000–24500 years bp (magyari, 2002; magyari et al., 2000; sümegi et al., 1999; járainé komlódi, 2000). at the depth between 480 and 430 cm one pollen shows a not interpretable sandy, silty sediment layer. this accumulation did not help the preservation of pollen grains. micro-stratigraphic analyses suggest slight windblown sand movements that can be explained by a short dry, cold period. sand movement of this age has not been identified in the nyírség so far but research carried out in the danube-tisza interfluve (krolopp et al., 1995) suggests sand movement of similar age (25200±300 bp). magyari (2002) indicates steppe–tundra vegetation between 24500 and 22700 years bp when characterising the vegetational phases of the northeastern part of the great hungarian plain. pollen content of the sediments between 430 and 360 cm suggests wetter climate again. pollen comp osition can be characterised by a mixed foliage taiga forest. this milder climate can be shown at several places in the carpathian basin (járainé komlódi, 1969, 1970; borsy and félegyházi, 1991; sümegi and magyari, 1999; félegyházi and tóth, 2003, 2004) characteristic for the period between 22700 and 21400 years bp. pollens upwards in the sediment series ind icate that the climate became more-and-more continental gradually. this fits well in the vegetational phase prevailed between 21400 and 18500 years bp (magyari, 2002). severe winters and dry, warm summers destroyed woodland vegetation and only grasses survived among herbaceous plants. this is indicated in the pollen spectra by that the ratio of pine pollens fall below 10% while that of grass species (gramineae) increases up to 60%. after this pollen accumulation was terminated, the bed was covered by a 200 cm thick wind-blown sand stratum. vegetation composed of cold steppe grasslands, then it was dried out as well and the surface of the alluvial fan was shaped by cold, sometimes stormy winds. formation of this sediment stratum took place around18500–14600 years bp. the sediments containing pollen appear again at the depth of 150 cm. pollen distribution is dominated by pine in 80% regarding arborescent vegetation. the remaining 20% is presented by deciduous trees and herbaceous vegetation with diverse taxon composition. at the time of the deposition of this stratum lacustrine conditions characterised this part of the bed. 26 lóki et al. (2012) with the gradual warming of the climate deciduous trees – birch (betula) first, then alder (alnus), willow (salix), linden-tree (tilia) and oak (quercus) appeared, however, scots pine (pinus sylvestris) was still present on the sand. hazel (corylus) was present in the underwood of oak forests as well. this sediment stratum represents the forest advancement phases of the postglacial time and the start of the early holocene. results of the palynological analyses of the cores from the borehole drilled in the other bed remnant between érpatak and nagykálló are the same as those of the borehole in the vicinity of újfehértó. thickness of the late glacial wind-blown sand is almost 200 cm at both locations. it can be also concluded from the analysis results of the samples from the two boreholes that at the time of formation of the lower sediment series lacustrine conditions prevailed instead of the previous fluvial conditions, i.e. the rivers accumulating the alluvial fan did not flow through the alluvial fan due to the depressions forming in the foreground of the mountains. in the dry period winds buried the abandoned beds completely at places or partially elsewhere. only smaller sections of these beds can be observed nowadays. conclusion in the development of the surface of the alluvial fan in the nyírség wind also had an important role apart from water. rivers accumulated vast amount of sandy sediments in the alluvial fan accumulating in the foreground of the mountains to the körös rivers. flow direction of these rivers changed several times during the accumulation of the alluvial fan. winds re-worked sandy sediments on the surface in the dry periods of the würm then fluvial sediment series covered the aeolian deposits in the wetter periods. although there is no direct evidence for this in the nyírség but the presence of wind-blown sand in the deeper strata of the alluvial fan was detected with the help of electronmicroscopic analysis of sandy sediments from cores drilled in the danube-tisza interfluve (borsy et al., 1987). applying electron-microscopic analysis on the sandy sediments of the alluvial fan of the nyírség in the future the aeolian or fluvial development of the strata could be determined. stratigraphic and morphological research of the last the decades focused only on the near surface (< 20 m) strata of the alluvial fan. deposition and re-working of these sediments took place in the last 30000 years. based on the research carried out so far it can be stated that sand was in motion in the nyírség at several times in the holocene as well after the aeolian land formation in the upper pleniglacial and the late glacial determined in the 1980s (table 1). in the first half of the holocene sand movement took place in the boreal phase and in dry periods of the atlantic phase thus the aeolian shaping of the land can be explained by climatic reasons. in the second half of the holocene the land shaping effect of wind probably prevailed in a much smaller area and it was associated with the activity of man. naturally, periods of drier climate had an important role in the aeolian land shaping due to anthropogenic effects. fig. 10 palynological and grain-size distribution diagrams of the sediments from the bed remnant in the vicinity of újfehértó aeolian surface transformations on the alluvial fan of the nyírség 27 table 1 chronological order of holocene sand movements climate periods of europe archaeological chronology geochronology pollen climate sand movement (bp) climatic+anthropogenic old new 2000 ad s u b a tl a n ti c s u b a tl a n ti c 0 1700 ad modern era b e e c h i i bagamér 230-90 osl (kiss, t.) bagamér 430-350 osl (kiss, t.) 1300-1700 ad little ice age erdőspuszta osl 900-1000 (kiss, t.) 600 ad drying maximum deserta avarorum 450 ad time of the great migrations bagamér 1370, 1100, 960 osl 1 ad roma, sarmatians, dacians bp. 2000 hosszúpályi sarmatian pot (lóki, j.) b ü k k i 300 bc climate optimum 2600 bp 2500 bp bagamér 2050 osl(kiss, t.) 850 bc iron age celts, veneti s z u b b o re a l s z u b b o re a l s bagamér 2450 osl(kiss, t.) 1200 bc drying maximum migration of marine cultures, defeat of troy, dorians, hebrew gégény 14c 3740 (lóki, j.) 2100 bc climate optimum palace farming in minos, crete 2800 bc bronze age hosszúpályi bronze age pot remnant (lóki, j.) 3000 bc drying maximum nile valley, mesopotamia irrigation agriculture bp. 5000 o a k 5600 bp 5700 bp bagamér 6000 osl (kiss, t.) 4400 bc copper age atlantic a tl a n ti c bagamér 7070 osl (kis,s t.) 7300 bp b o re a l 6000 bc neolithic bp. 8000 8300 bp hazel boreal bp. 9000 s il v e r b ir c h bagamér 9200 osl (kiss, t.) kántorjánosi 14c 9300 (lóki, j.) 9600 bp preboreal south nyírség pollen (félegyházi, e. and lóki, j.) 10200 bp dryas 11200 bp 10000 bc mesolithic dryas 28 lóki et al. 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(2009) pp. 15-22 assessing temperature signal in x-ray densitometric data of norway spruce and the earliest instrumental record from the southern carpathians kern, z. 1* popa, i. 2 1: institute for geochemical research, hungarian academy of sciences, h-1112 budaörsi út 45, budapest, hungary 2: research station for norway spruce silviculture, forest research and management institute, câmpulung moldovenesc, romania *correspondence: e-mail: kern@geochem.hu, tel: 00 36 1 3092600/1106, fax: 00 36 1 3193137 abstract radiodensity data derived from norway spruce were studied from a southern carpathian site. maximum density record showed significant positive relationship (r=0.59) with the growing season (april-september) air temperature and minimum density (mnd) record showed clear and significant negative response (r=-0.41) to june-july mean air temperature. this significant mnd response to climate is a novel result as traditionally this densitometric parameter was regarded not to carry any meaningful climatic signal. derived temperature sensitive proxy records were compared to instrumental data of sibiu (nagyszeben/hermannstadt) the oldest available regional station. results of the running window correlation analysis pointed out notable inhomogeneities in the instrumental data before 1906. the sibiu temperature series should be subjected to scrutiny revision to clean it from inhomogeneities. key words: maximum latewood density, minimum earlywood density, picea abies, inhomogeneous instrumental temperature, dendroclimatology, romania introduction norway spruce (picea abies (l.) karst.) is the main species of the carpathian coniferous belt. its longevity is documented to reach 576 years (schweingruber f. h. – wirth c. 2009). norway spruce deserves special attention in the regional tree-ring research due to its importance from viewpoints of silviculture, dendroclimatology and dendroarchaeology. several studies have been already conducted to decipher climatic information preserved in ring width variability of spruce in the carpathians (e.g. bednarz z. et al. 1998-99, szychowskakrapiec e. 1998, popa i. 2003, 2004, 2005, savva y. et al. 2006, kaczka r. – büntgen u. 2007, kern z. – popa i. 2007, popa i. – kern z. 2007, bouriaud o. – popa i. 2009), while other parameters were analysed solely in the tatras (büntgen u. et al, 2007). however, wood density data from spruce are also available from three eastern and the southern carpathian sites. these sites were sampled in the frame of a global dendrochronological sampling campaign. these southern carpathian stands were used to assess spatial teleconnections in the network (schweingruber f. h. 1985) and in a broad scale dendroclimatological comparison (schweingruber f. h. et al. 1987). nevertheless, the climatic signal preserved in the radiodensity data has never ever been explored separately. the fact that schweingruber f. h. (1985) defined an individual densitometric zone in the european coniferous belt centred on the southern carpathians gives even further interest for the climatic interpretation of the southern carpathian archive wood density data. an additional motivation of this study was to test the earliest instrumental temperature record of the region (ro-sibiu/h-nagyszeben/g-hermannstadt) in order to see if its known inhomogeneities might be tracked comparing with climate sensitive proxy records. curiosity emerged as proxy/data comparisons suggested biased early instrumental data for many sites in europe (e.g. moberg a. et al. 2003, frank d. et al. 2007a, winkler p. 2009), and corrections were recommended for some temperature data even before the 1900s. material and methods radiodensity data wood density data originated from itrdb database (schweingruber f. h. 2000, noaa 2009), from which database a southern carpathian timberline site (45.30n, 23.67e, 1650 m a.s.l.) near novaci in the parang mts (fig. 1) was selected for this study. sampled species was norway spruce. the archive dataset contains 30 series of maximum and minimum density from 15 trees (each tree represented by two series). the wood density data were developed by the x-ray densitometric technique (polge h. 1970, schweingruber f. h. et al. 1978) in the framework of a global dendrochronological sampling network of conifers (schweingruber f. h. 1985). maximum and minimum density values are the characteristic parameters of the radial wood density structure. in a given tree ring the density maximum is linked to latewood and minimum is linked to earlywood (schweingruber f. h. et al. 1978). the novaci dataset covers a 178-years long period, 1804-1981 ad, so despite its almost tridecadal antiquity it 16 z. kern – i. popa joeg ii/3-4 is still the longest wood densitometric record from the entire eastern and southern carpathian domain. mean tree age is 88 years and ranges from 35 to 178 years. replication decays before ad 1944 down to 4 at ad 1827 (fig. 2). a sole series dates before ad 1821. average maximum and minimum density of the population is 0.769 and 0.256 g/cm 3 , respectively. average maximum density value fits nicely in the range found for norway spruce in the tatras (büntgen u. et al. 2007), but lower than the value reported from a slovenian alpine spruce stand (levanič t. et al. 2009). average minimum density fits similarly well in the range presented for spruce in the alps (schweingruber f. h. et al. 1978). standardization, index calculation raw density data were subjected to standardization procedure to eliminate non-climatic trends and emphasize climatic signal (cook e. r. et al. 1990). a relatively stiff cubic spline function (50% frequency cut-off at 300yrs) was fitted to each individual series (cook e. r. – peters k. 1981). raw density data were converted into index values as ratio between measured and modelled values. final population indices for maximum density (mxd) and minimum density (mnd) were computed as biweigth robust mean (cook e. r. 1985). variance of derived mxd and mnd chronologies was adjusted to minimize bias due to changing sample replication (osborn t. j. et al. 1997, frank d. et al. 2007b). stability of climate related signal preserved in the index series was controlled by the expressed population signal (eps) statistics applying the standard acceptance threshold of 0.85 (wigley t. et al. 1984). mean interseries correlation (rbar) and eps were calculated for 40 yrs moving window with 20 yrs steps. standardization and index calculation procedure was carried out using the arstan software (cook e. r. – krusic k. j. 2006). instrumental data for climate response analysis monthly temperature means of grid-box enclosing the novaci tree-ring site (fig. 1) were extracted from the cru ts2.1 database (mitchell t. d. – jones p. d. 2005) from 1901 to 1981. the longest instrumental temperature record of the southern carpathian region originates from sibiu a prominent town of transylvanian saxons (fig. 1). observations at sibiu began in 1851. monthly mean temperature data since 1851 are available via the climate explorer (van oldenborg g. j. et al. 2005). sibiu is regarded as the most precise and most reliable temperature record in the region (ţîştea d. at al. 1966). however, location of observation as well as termini and calculation method of daily mean temperature had changed a couple fig. 1 location of the sample site (filled square) and sibiu (filled triangle) the earliest meteorological station of the region of southern carpathians. right corner: location of romania shown by black shading. left corner: black rectangle shows the location of the site in the southern carpathians joeg ii/3-4 assessing temperature signal in x-ray densitometric data of norway spruce and the earliest instrumental record from the southern carpathians 17 of times during the station’s history (table 1). for instance, daily and inherently monthly mean temperatures are positively biased by the (t7+t14+t21)/3 calculation method compared to (t7+t14+2*t21)/4, the so-called kaemtz-method (see dall’amico m. – hornsteiner m. 2006). nevertheless mean temperatures are obviously suffering negative bias due to the earlier morning (6 vs. 7 a.m.) and the later evening (22 vs. 21 p.m.) readings before 1880. climatic signal analysis pearson’s correlation coefficients have been computed between mxd, mnd and gridded monthly mean air temperature to assess the temperature effect of each month on the annual radiodensitometric characteristics of spruce. months from the june of the previous year to october of current year of tree-ring formation were involved in the analysis. after the first trial, bimonthly means of august-september (as) for mxd and junejuly (jj) for mnd were also invoked. in addition, the april-september (amjjas) mean temperature was also included into the mxd comparison. correlation coefficients were compared to 95% significance level derived from student’s t-test to evaluate their importance. investigation was restricted to the period after 1906, because the first five years were designated as biased instrumental data (see later). temporal stability of relation between mxd/mnd and sibiu record was investigated by running correlation computed in 21-year moving windows. moving window correlation technique is a standard tool to trace temporal stability in proxy-climate correlations (aykroyd r. g. et al. 2001). the choice of any window width is somewhat arbitrary but the applied 21-year window over the screened 130-year long period is an acceptable compromise between a very narrow window (with a higher sampling error) and boarder window (which approximate the behaviour of the full dataset) (aykroyd r. g. et al. 2001) and it is in conformity with choice of similar dendroecological studies (e.g. carrer m. et al. 2007, friedrichs d. a. et al. 2009). timing of detected unusual shifts was compared to events in station history. results and discussion novaci spruce mxd and mnd record both density indices (fig. 2a) preserve quite strong common signal as evidenced by the high and stable signal strength statistics. mean rbar (eps) is 0.44 (0.95) and 0.27 (0.91) for mxd and mnd, respectively. same statistics calculated in moving windows (fig. 2b,c) showed exceptional signal stability and present that the relatively higher values found in mean values for mxd is permanently valid through the entire studied period. eps values exceed the 0.85 threshold level suggesting robust chronology for both radiodensitometric parameters. the correlation between mxd and mnd is 0.02, indicating that independent environmental information is preserved in the proxies. wimmer r. and grabner m. (2000) also found that in a spruce stand the density measured in earlywood (e.g. mnd) were widely independent from latewood, suggesting that they are not under the same control. relationship between temperature and maximum/minimum density of spruce wood in the case of mxd, august and september yielded the largest coefficients among monthly means 0.56 and 0.39, respectively (fig. 3a). these findings broadly agree with the previous observations carried out at various sites in the carpathians (schweingruber f. h. et al. 1987). however, comparison with april, may and june showed also significant positive coefficients. the coefficient of july has not reached the 95% significance level but still positive and exceeds the other monthly responses. regarding as bimonthly mean temperature the coefficient slightly improved, and the multi-monthly amjjas presented even bit higher coefficient (0.59). the latter one was found as the optimal target season corresponding to the climate information of spruce mxd table 1 recorded changes of observation conditions of the sibiu/nagyszeben/hermanstadt station (source: ţîştea d. et al. 1966). row-head codes: a: date of change; b: location of observation; c: termini (time of regular thermometer readings) and calculation method of daily mean temperature. note the width of cell is not proportional with the duration of the represented period! a 1851 january 1861 1880 1887 may 1897 august 1900 july 1905 october 1921 1940 september 1947 august b weinanger platz 14 saggasse 15 elisabethgasse 9 schiffbäumel 3 langgasse 5 reisbachgasse 9 weber gasse 6 strada riului 5 dimitri anghel 3 c 6-14-22 arithmetic mean 7-14-21 arithmetic mean 7-14-2*21 kaemtz-method 8-14-20 köppenformula 18 z. kern – i. popa joeg ii/3-4 f ig . 2 r a d io d e n si to m e tr ic c h ro n o lo g ie s o f sp ru c e f ro m n o v a c i a n d g ra p h ic a l il lu st ra ti o n o f si g n a l st re n g th s ta ti st ic s c a lc u la te d f o r 4 0 y rs m o v in g w in d o w w it h 2 0 y rs s te p s, w h e re b la c k ( g re y ) c u rv e s a n d s y m b o ls s h o w m x d ( m n d ) re c o rd s. a : in d ic e s o f m a x im u m ( m x d ) a n d m in im u m ( m n d ) d e n si ty ;. b : in te rs e ri e s c o rr e la ti o n ( r b a r) ; c : e x p re ss e d p o p u la ti o n s ig n a l (e p s ). d a sh e d h o ri z o n ta l li n e d e n o te s th e 0 .8 5 t h re sh o ld l e v e l; d : sa m p le d e p th in the tatras (büntgen u. et al. 2007) and in the alps (frank d. – esper j. 2005). the weakened mid-summer temperature response seems to be a characteristic pattern of the spruce mxd response. both for the alps and tatras june coefficient dropped below 95% significance level (frank d. – esper j. 2005, büntgen u. et al. 2007). in the case of the southern carpathian spruce mxd chronology a bit different pattern was found. june coefficient is significant while for july it showed low values. joeg ii/3-4 assessing temperature signal in x-ray densitometric data of norway spruce and the earliest instrumental record from the southern carpathians 19 interesting to note that in a recent study on two slovenian spruce stands reported september mean temperature as the main climatic driver of cell wall thickening (levanič t. et al. 2009). this discrepancy between the slovenian and south carpathian spruce mxd responses, however, can be easily explained as the growing season at the more temperate slovenian sites is longer compared to the more continental southern carpathian timberline. the shorter vegetation period means earlier cell maturation as well. none months from the year before tree-ring growth showed significant effect on cell wall thickening during the subsequent year. this lack of responses from the year preceding the growth is normal for the mxd (schweingruber f. h. et al. 1987). in the case of mnd june and july showed the strongest results -0.33 and -0.34, respectively (fig. 3b). regarding jj bimonthly mean temperature the correlation further improved (-0.41). may mean temperature yielded similarly negative coefficient albeit it slightly lags behind the 95% significance level. this response is especially exciting as the pioneer milestone study of radiodensitometric dendroclimatology conducted in the alps (schweingruber f. h. et al. 1978) experienced no any clear relationship between this densitometric parameter of spruce and climate variables, consequently mnd was usually neglected in later researches. a sole exception is the study of wimmer r. and grabner m. (2000) from the following 30 years. they analysed 16 anatomical variables (including also mnd and mxd) averaged from 20 norway spruce trees over a relatively short, 40-year long, tree-ring sequence. they found poor climatic response in mnd. however the neglected potential of mnd as climate archive can be emphasized referring to a very recent study. grabner m. et al. (2009) investigated mnd record fig. 4 fluctuation of coefficients of 21yrs moving window correlation computed between radiodensitometric indices of novaci spruce samples and their optimal bimonthly temperature target from the sibiu record. a: maximum density vs. as, b: minimum density vs. jj. dashed horizontal lines denote the 95% significance levels fig. 3 columns indicate the pearson’s correlation coefficients computed between monthly and multi-monthly mean air temperatures and maximum (a) and minimum (b) density indices over the 1906-1981 interval. few coefficients are given near to the corresponding column. horizontal dashed lines denote the 95% significance level 20 z. kern – i. popa joeg ii/3-4 in a dataset of juvenile spruce stands. surprisingly they found stronger correlation between mnd and climate variables than with mxd. statistical results suggest that dominantly june-july thermal conditions determine the minimum earlywood density of spruce tree ring in the southern carpathians. higher june-july air temperature seems to retain cell wall thickening and/or to produce larger lumen diameter in the earlywood. may also has some minor role in this process. we propose that only the late half of may preceding june affects the process, and the corresponding coefficient become non-significant as the monthly means integrates also the daily temperatures from the early half of the month. the relatively high positive coefficient of october lacks explanation as cell maturation in the earlywood section is probably ceased for mid-autumn. even more, it might be a fake response due to biased instrumental reference (see later). comparison with the earliest local instrumental temperature record for the sake of brevity out of the many prepared moving window correlation (hereafter mwc) analyses only a few arbitrary selected graphs are presented. they were chosen to best illustrate our conclusion. fig. 4 shows the temporal fluctuation of the correlation coefficient calculated with the optimal bimonthly mean temperature target of both radiodensitometric parameters (i.e. as vs. mxd; jj vs. mnd). although mnd lost significance in the last decade, coefficients generally exceed the significance levels over the last seven decades. in contrast, coefficients of both densitometric parameters drop below significance level at 1905-1906. the coefficients reach significance level again before 1896 and 1880 for mxd and mnd, respectively. each date can be found in the station movement history. this suggests that between 1880 and 1905, when the location of observation frequently changed settling in one place, as short as 3 to 9 years homogeneity of observation conditions were failed to maintain. as gridded temperature data largely relies on sibiu record before 1920 in the region, this is the reason why the proxy/climate relationship was finally analysed on the truncated record from 1906. coefficients of mwc calculated between mxd and april monthly mean temperature are presented in fig. 5a. coefficients are well above significance level during the early decades, they start to decline from 1880, and sink permanently below significance level from 1886. they fluctuate around zero level over few decades, afterwards abruptly increase from 1922, and exceed the significance level from 1924. the period of weakened even more non-significant coefficients coincide with the era of t07-t12-t21 readings, but also include the hectic station movements. the date of sudden recovery of positive correlation relationship coincides with the introduction of kaemtz-method. the last sudden drop from 1943 to 1944 is a sole event which is not mirrored in station history. however, its time is equally near to a station movement (i.e. 1940) and a methodological change (introduction of köppen-formula) which was accompanied with station movement, as well. mwcs calculated between mnd and may and october monthly mean temperatures are presented in fig. 5b. temporal evolution of mwc coefficients show strange shifts again. may coefficients fluctuate slightly below the 95% significance level through the main part of the studied period. some decline can be seen during the last decade but a very unusual drift appears at the earliest time. coefficients steadily increase before 1883, fig. 5 fluctuation of coefficients of 21yrs moving window correlation computed between radiodensitometric indices of novaci spruce samples, and a few arbitrary chosen monthly mean temperature targets from the sibiu record. a: maximum density vs. april, b: minimum density vs. may (open squares) and october (filled squares). dashed horizontal lines denote the 95% significance levels joeg ii/3-4 assessing temperature signal in x-ray densitometric data of norway spruce and the earliest instrumental record from the southern carpathians 21 change sign at 1881, and become significant before 1878. the period of unusual positive coefficients broadly coincides with the era of t06-t12-t22 readings. october coefficients show more sudden changes. the first from 1886 to 1887 when coefficients change from negative to positive, and the second after 1906 when swap sign again. both date link to station movement. the coefficients are close to zero for a decade, then start a gradually rise from 1921, and abruptly jump to significance level after 1925. coefficients fluctuate around significance level until 1946, after drop suddenly to zero level. the period of positive, occasionally even significant, mwc coefficients of october coincides with the utilization of the aforementioned kaemtz-method. we suspect that the found positive response to october mean temperature might be the effect of the kaemtz-method. conclusions climatic information was evaluated for archive norway spruce maximum and minimum radiodensity data from a southern carpathian location. spruce mxd record showed significant positive relationship with the growing season (may-september) air temperature. similar response was found for the same species in the tatras and the alps. however, some characteristic discrepancy was also experienced (i.e. july vs. june signal weakening). the southern carpathian mxd response showed distinct difference compared to the slovenian one, too (i.e. strongest reaction for august vs. september). these small differences compared to surrounding areas could plausibly explain the existence of the individual densitometric provenance defined by schweingruber f. h. (1985) for the southern carpathians. spruce mnd record showed clear and significant negative response to june-july mean air temperature. this is a novel result as traditionally this densitometric parameter was regarded not to carry any meaningful temperature signal. hitherto dendroclimatological research focused exclusively on radial growth properties in the southern carpathians (e.g. soran v. et al. 1981, popa i. – cheval s. 2007, kaczka r. – büntgen u. 2007). in the present study, however, we point out that densitometric properties have also great potential both in ecological and palaeoclimate reconstructions, and future researches are recommended in this field. derived temperature sensitive proxy records were compared to instrumental data of the oldest available regional station. results of the moving window correlation analysis showed strange shifts coinciding with changes in station history. considerable inhomogeneities can be suspected in the instrumental data before 1906. the sibiu temperature record would have eminent importance in the regional historical climatology due to its completeness and exceptional length. nevertheless, this prominent secular record is hardly usable as temperature target in regional proxy paleoclimatological research until a scrutiny revision is done. acknowledgements the research was funded by otka k67583. popa i. is supported by idei id65 project. this is budapest tree-ring laboratory contribution no 19. references aykroyd r. g. – lucy d. – pollard a. m. – carter a. h. c. – robertson i. 2001. temporal variability in the strength of proxy-climate correlations. geophysical research letters 28(8): 1559-1562. bednarz z. – jaroszewicz b. – ptak j. – szwagrzyk j. 19981999. dendrochronology of norway spruce (picea abies (l.) karst.) in the babia góra national park, poland. dendrochronologia 16-17: 45-55 bouriaud o. – popa i. 2009. comparative dendroclimatic study of scots pine, norway spruce and silver fir in the vrancea range, eastern carpathian mountains. trees-structure and function 23: 95-106 büntgen u. – frank d. c. – kaczka r. j. – verstege a. – zwijacz-kozica t. – esper j. 2007. growth responses to climate in a multi-species tree-ring network in the western carpathian tatra mountains, poland and slovakia. tree physiology 27: 689-702 carrer m. – nola p. – eduard j. l. – motta r. – urbinati c. 2007. regional variability of climate-growth relationships in pinus cembra high elevation forests in the alps. journal of ecology 95: 1072-1083. cook e. r. – peters k. 1981. the smoothing spline: a new approach to standardizing forest interior tree-ring width series for dendroclimatic studies. tree-ring bulletin 41: 45-53 cook e. r. 1985. a time series analysis approach to tree-ring standardization. ph.d. dissertation, the university of arizona, tucson pp.171. cook e. r. – briffa k. – shiyatov s. – mazepa v. 1990. tree– ring standardization and growth–trend estimation. in: cook e. r. – kairiukstis l. 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(2009) pp. 23-29 documentary evidence on weather conditions and a possible crisis in 1315-1317: case study from the carpathian basin vadas, a. eötvös loránd university of sciences, department of medieval and early modern european history, address: 17/a csipkebogyó utca, budapest, hungary, h-1221. e-mail: vadinka86@gmail.com abstract in the last decades, climate variabilites of the fourteenth century gained great interest and became a subject of numerous research papers. due to the relative lack of sources referring to the climate of the carpathian basin, merely based on written evidences continuous climate reconstruction of the period is not possible. nevertheless, there are cases when, due to available contemporary evidence, still some conclusions can be drawn. in this paper an investigation is carried out on one specific environmental crisis characterized by several flood events of european rivers caused by repeated abundant rainfalls; moreover, summer and winter temperatures were lower than the average of the preceding century. as a result of unfavorable environmental and economic conditions, a great number of western and central european sources reported on famines caused by the destruction of cereals. mainly based on austrian and czech narratives as well as hungarian charters, in the present paper an attempt was made to collect all the available sources on prevailing weather conditions and their possible effects in the hungarian kingdom mainly referring to the period of 1315-1317. key words: climate variability, environmental crisis, weather events, floods, documentary evidence weather conditions in the 14th century climatic conditions of the middle ages is a subject of several research papers, either as long-term investigations (e.g. brázdil r. – kotyza o. 1995, pfister c. et al. 1998, glaser r. 2001, shabalova m. v. – van engelen a. f. v. 2003) or in the form of case studies on extremes events (e.g. kiss a. 2003, rohr c. 2005). being already a part of the little ice age, the 14th century is still considered as a transitional period between the medieval warm epoch and the little ice age, and this period poses several questions concerning variabilities of climate. a number of investigations pointed out that during this century temperatures in western and central europe started to decrease (e.g. lamb h. h. 1988, pfister c. et al. 1996, pfister c. et al. 1998, yan z. et al. 1999). in the alps, the aletsch glacier started to advance from the 1120s and reached its maxima at around 1350 (holzhauser h. 1997) which can be related to the decrease of temperature in the alps from the second half of the 12th century to the 14th century. climatic changes in the czech lands are more questionable, since it is not possible to provide clear evidence on such phenomena in the first decades of the century (brázdil r. – kotyza o. 1995). in this period temperature decreased and also wet years became more frequent, especially in the western european territories. in central and eastern europe there is no definite evidence for precipitation increase. for example, climate research of the czech lands did not show an increase of precipitation during the 14th century (brázdil r. – kotyza o. 1995). nevertheless, water-level increase was detected in the mines of goslar (in germany) and iglau (today jihlava in czech republic) (steensburg a. 1951). investigations on the great eastern european plain pointed out a drier period (lamb h. h. 1982). however, the water level of the caspian sea was several meters higher than nowadays (gumilëv l. n. 1968), which does not reinforce the theory of a drier period in eastern europe. from the 13th century the number of climatic extremes increased in western europe and so did the number of sea floods in the northwestern european region (lamb h. h. 1995). on the other hand, central european investigations do not provide evidence on an increasing number of climatic extremes in the first half of the 14th century (brázdil r. – kotyza o. 1995). therefore, the weather of western europe was cooler and wetter than in the previous centuries. weather conditions of europe started to change and it had an effect on the food supply of the european population. during the 14th century crop prices increased (le roy ladurie e. 2004, pustil’nik l. a. – yom-din g. 2004) and in the years of the famine (1315-1317) the price of cereals were extremely high (lucas h. 1930). consequences of extreme weather in europe between 1315 and 1317 the second decade of the 14th century gained special attention among climate scientists. the 1310s was the decade in which “years without summer” occurred (pfister c. 1992). in the mid-1310s a serious famine took place all over europe (jordan w. c. 1996). in england, for example, unfavorable weather conditions started 24 a. vadas joeg i/3-4 from 1314 with precipitation increase and temperature decrease, whereas prices were so high that in 1315 the king had to fix the maximum price of ale and meat (kershaw i. 1973). in france, continuous rains started in may 1315. due to great abundance of rains, cereals could not come to maturity and food shortage caused serious famine. there was no vintage in 1315, and the price of wine was high in 1316 (alexandre p. 1987). according to emmanuel le roy ladurie (2004), in 1316 three million people died partly because of the lack of food. same weather conditions and problems occurred in the netherlands: the years of 1315-1317 were wet and serious famine occurred in ypres and bruges (le roy ladurie e. 2004, 2006). in the mediterranean, historical records also indicate floods mainly in northern italy, in the area of parma and modena (alexandre p. 1987). historical records of the iberian peninsula are not yet published, but a dendroclimatological research indicates warmer period in the first half of the 14th century than in the preceding decades (büntgen u. at al. 2008). table 1 floods of rivers in the surroundings of hungary between 1315 and 1317 year month source place flood of river 1315 september chron. de gest. prin. mgh ss rer. germ. vol. 19. 84. rivers in austria 1315 after 25 july chron. aul. reg. 365. czech kingdom rivers in bohemia and moravia 1316 23, 24, 28 june cont. canon. s. rud. salis. 822. triplex flood of the danube 1316 28 june ann. burgh. mgh ss vol. 24. 62. danube 1316 anon. leob. chron. 33-34. austria, hungary danube and mura rivers 1316 anon. leob. chron. 33. werfen, austria salzach river 1316 chron. austr. 241. danube 1316 ann. mellic. cont. zwetl. ter. 659. danube and its tributaries 1316 mart. meist. ann. gorl. 8. neisse river 1316 chron. aul. reg. 379. czech kingdom, austria floods 1317 ann. zwetl. 681. danube and its tributaries 1317 ann. mellic. cont. zwetl. ter. 666. czech kingdom, austria, hungary danube records are as well available related to the german territories: annals and other narrative sources inform about flood events and extreme weather conditions from bavaria to estonia (glaser r. 2001, alexandre p. 1987). besides the historical records dendroclimatologic data from the valley of the rhine also supports the theory of the consecutive wet years (le roy ladurie e. 2003). evidence referring to surrounding areas historical records from austria and the other neighboring territories of the carpathian basin are very important in the light of the fact that narrative sources and annals from the hungarian kingdom are rare in the middle ages. in austria, investigations were carried out based on historical records (pautsch e. 1953, rohr c. 2005, 2007), which provide further evidence to a possible comparison. it is interesting to note that according to some investigations based on o18 content of stalagmite records, summer temperatures in this period (mangini a. et al. 2005) were not lower than in the preceding centuries. nevertheless, according to pfister (1996) winter temperatures were in the decade of the famine 1.7°c lower in the region of the alpes than nowadays. moreover, a number of annals and chronicles mention floods on the rivers of austria in 1315, 1316 and 1317 (table 1). from the czech lands data are available on dry weather conditions before 25 july 1315; however, after this time chroniclers reported on great floods and famine (chron. aul. reg. 365.) which continued in 1316. the same chronicle mentions bad harvest in 1317. in the western neighborhood of hungary, in austria and the czech lands these three years were rich in flood events. record on famine is as well available referring to austria, the czech kingdom and as well to poland (ann. cist. in hein. 546.). fluctuation of crop prices in the 1310s also reflects unfavorable weather conditions (table 2). as a conclusion we can say that, similarly to western europe, in the neighbouring countries west and north to hungary, presumably connected to weather conditions, floods and famine occurred, negatively affecting local population occurred in 1315-1317. joeg i/3-4 documentary evidence on weather conditions and a possible crisis in 1315-1317: case study from the carpathian basin 25 table 2 corn prices in the 1310s in the countries surrounding hungary date place barley (hordeum) wheat (triticum) wheat (siligineus) oat (avena) conditions source 1312 zwetl 70 denarius ½ talentum 3 solidus and 15 denarius 60 denarius on the 26th of march. cont. zwetl. ter. 1312 morvavia - 30 grossi of prague -- after bad harvest chron. aul. reg. 1312 zwetl -10 talentum -- around easter ann. zwetl. 1312 mattsee --3 solidus 60 denarius serious famine ann. mat. 1312 austria 60 denarius 4 solidus 3 solidus 60 denarius famine chron. austr. 1313 zwetl -6 denarius 4 denarius -good harvest ann. zwetl. 1313 zwetl 4 denarius 6 denarius 4 denarius 4 denarius good harvest, cheapness cont. zwetl. ter. 1313 salzburg - 3 solidus and 2 denarius --at easter cont. can. s. rud. salis. 1317 salzburg --5 denarius -famine cont. can. s. rud. salis. 1317 burghausen ----great famine ann. burgh. 1319 prague -- 1 grossi of prague - low prices after good harvest, chron. aul. reg. information on climate of hungary in the early 14th century referring either historical or present hungary, due to relative scarcity of available contemporary written evidence, research on climatic conditions as well have to rely ont he results of natural scientific research and archaeological investigations. some studies in the field of archaeological research suggest that a drier period prevailed in the 13th century. however, it is very probable that the climatic conditions of hungary started to change in the beginning of the 14th century and the climate became wetter in these decades (rácz l. 2006). it is, however, a general problem of natural scientific and archaeological research that in most cases changes can be detected, but it is difficult to differentiate the main reasons: it is uncertain whether mainly human impact or a possible climate change is more responsible for the changes. this question arises, for example, in current results of sand-dune research or waterlevel-change investigations of larger lakes of the carpathian basin. sand-dune studies, for example, referring to the danubetisza interfluve indicate sand-movement in the first half of the 14th century (kiss t. et al. 2005). investigations on the main water-level tendencies of lake balaton pointed out that the water level had an increasing trend during the 14th century (sági k. 1968, kiss a. 1999b). geoarchaeological investigations show a cooling period in the 14th century (sümegi p. et al. 2005). a 1000-year dendroclimatological reconstruction is as well available on summer temperatures, referring to the eastern carpathians (romania), which show cool years around 1300; however, this research points out hot summers in the 1310s (popa i. – kern z. 2008). nevertheless, due to the location of sample site, this reconstruction might not completely refer to the conditions of the carpathian basin in general, and the influence of more easterly areas should be as well considered. thus, based on the presently available information, only a rather mosiac picture can be drawn. it is, however, appear rather clearly that a general change in environmental conditions can be detected in the early 14th century hungary. concerning contemporary documentary evidence of hungary, some investigations were already carried out referring to weather conditions of the 1310s in hungary (kiss a. 1999a). moreover, a case study on the comparison of conditions between western europe and hungary in the mid-1310s suggested that, unlike west and north to us, no traces of a major crisis in 1315-1317 occurred in the hungarian kingdom (szántó r. 2005). nevertheless, according to our opinion a deeper comparison of contemporary evidence of the neighbouring areas, as well as some additional, newly investigated domestic evidence can provide a not only slightly different, but clearly more detailed picture of what happened in the carpathian basin in the years of 1315-1317. 26 a. vadas joeg i/3-4 weather-related documentary evidence in hungary: 1315-1317 largest number of contemporary evidence can be investigated first in the summary (regesta) collection of the angevin chartulary (an. okl. vol. i–xiv.), in which all presently available charter evidence of the reference period in hungary are listed. thus, the basis of our investigation was not only the years of 1315-1317, but a wider time-scale, namely the period of 1301-1330. it is due to the fact that, as we will see, clear evidence referring to the investigated period is available in charters issued after 1317. apart from hungarian charters, annals and chronicles of neighbouring countries were also examined (table iii and fig 1). despite the fact that only a low number of weather-related data is available concerning the first decades of the 14th century, some of the evidence provide interesting information. for example, one charter evidence (dl 63093) dated to 1309, referring to the village of lehatha (today horná mičiná in slovakia), reports on frequent previous flood events of the garam (today hron in slovakia) river, which might show some connections to the increase of flood frequency in the period around 1300 occurred in western europe. a charter from 1343 (dl 71639), transcribes another document from 1312 that is important for highlighting the food supply in the 1310s. the charter is seemingly a simple document which puts an issue in the sale of an estate on paper. the estate which is sold in this charter is called pethunye (petenia, romania), but what has to be emphasized here is that the reason for selling one sixth of this estate complex was supposed shortages in the near future. the charter was issued on 25 june, 1312, exactly the period of the usual date of the grain harvest, which indicates that the harvest was very poor. it does not mean that the harvest was poor over a broader region as the charter does not specify the reason for the supposed shortage or food supply in the coming year, but it is possible that it was due to weather conditions. a chronicle on the history of szepesség (today spiš-region in slovakia) compiled in the 17th century by caspar hain (hain g. 1910-1913), partly based on the local archival evidence, indicates a famine during three years around 1312 and mentions that cannibalism might have been present among the population. according to, for example, lucas (1930) this phenomenon was not unique in time of famines but in this case it could as well be the vivid imagination of a 17th century author. in spite of probable exaggerations and the fact that it is not a contemporary source, this chronicle can have a great importance from our point of view. the author of this chronicle was the mayor of lőcse/leutscha (today levoča in slovakia) and thus, had an easy access to the town archives. some of his reference suggest that he was familiar with, by now lost, medieval narratives, and thus, his descriptions about medieval period should be as well have to be considered (hain g. 1910-1913). thus, it is quite probable that caspar hain had access to reports referring to the early 14th-century famine. thus, it is quite probable that some time in the early or mid-1310s a famine took place in hungary. although hain dates this event to three years around and after 1312, but he also adds that the exact date is not sure (hain g. 1910-1913). table 3 weather related events in hungary 1315-1317 no. year day, month source place event 1 1309 dl 63903. lehotka (slovakia) frequent floods of river garam 2 1312 25 june (date of issue) dl 71639 petenia (romania) presumed food shortage in the future 3 1312 hain g. 13 szepesség (slovakia) serious famine in hungary, cannibalism 4 1316 anon. leob. chron. 33-34 hungary serious floods 5 1316 chron. aul. reg. 379 hungary serious floods caused by continuous rains, unusual weather 6 1317 24 february (date of issue) dl 1884. sava valley (croatia) hard conditions because of winter 7 1317 ann. mellic. 511. hungary floods of rivers 8 1318 dl 50333 keserű (romania) serious famine in the past concerning 1315, no direct evidence is available related to weather events of the hungarian kingdom. thus, it is yet uncertain whether or not abundant precipitation and floods, occurred from england through france to austria, reached the carpathian basin. however, contrary to 1315, some source evidence is available about the next year, 1316. the anonymus leobiensis chronicon informs about serious floods destroying villages along the joeg i/3-4 documentary evidence on weather conditions and a possible crisis in 1315-1317: case study from the carpathian basin 27 danube in austria and hungary. the chronicon aulae regiae (bohemia) reports on succeeding unusual weather events, and floods caused by continuous rains. thus, in this year not only the precipitation was greater than usual, but the number of weather extremes as well increased in the areas west to us. serious flood of river mura was reported in 1316, which probably as well reached hungary (anon. leob. chron. 33-34). in the same period, king charles robert passed the drava river (takes the water of river mura) with his army and we do not have any source reporting on difficulties. based on this we cannot state that this flood undoubtedly reached and caused problems in hungary. fig. 1 geographic names in medieval hungary, referred in the article a charter written in 1323 (dl 1884) transcripts the text of another charter dating back to 24 february 1317 provide evidence on the great difficulties of the royal army when, caused by hard winter conditions, they crossed the sava river. as no more details are available, no clear statement can be provided on the actual weather conditions disturbing the army from crossing the sava river. nevertheless, the winter of 1317 was, according to the chronicon aulae regiae, extremely long and cold (lasted until 28 march) in the czech lands. thus, there is a high probability that the winter of 1317 was also colder than usual in hungary. however, a deeply frozen sava river in itself would have allowed an easier pass to the king’s army. the last data to be discussed here is a, dated to 1318 (dl 50333). the charter mentions a certain stephen who gave proof of his charity when he helped his family during a time of serious famine. this is the only unquestionable contemporary written evidence from the carpathian basin which refers to famine in the preceding period. it does not specify when the famine took place, but the charter is a continuation of another document dating back to 1311, which means the famine mentioned in the charter took place some time between 1311 and 1318. the charter from 1318 was issued by the monastery of 28 a. vadas joeg i/3-4 várad (oradea, romania) concerning an estate called keserű (cheşereu, romania). seemingly, there was a famine in that region, which does not mean that it touched the whole country. however, the fact that the scribe did not specify which famine the charter refers to may indicate that it was a well known event and affected a broader geographical area. even if only a few written evidence is available related to a famine and possible environmental crisis of the mid-1310s (see fig 1), these sources provide clear evidence that the crisis, mainly in the form of high prices and famine indeed reached hungary. conclusion great parts of europe were clearly affected by the weather anomaly of the mid-1310s. as a result, great famine occurred in western and central europe. crisis clearly affected territories in the immediate neghbourhood: unfavourable weather conditions and famine occurred in austria, the czech lands and poland. whereas some case studies suggested that no contemporary information can support the idea that crisis also reached hungary in 1315-1317, it seems that some contemporary charters indeed suggest that signs of the same crisis and famine were present and caused problems in different parts of contemporary hungary. acknowledgements thanks are due to andrea kiss (szeged university) whose help in compleiting the article was fundamental. i am also grateful for the corrections of phillip slavin (yale university). abbreviations of primary sources an. okl. = anjou-kori oklevéltár. documenta res hungaricas tempore regnum andegavensium illustrantia. vol. i–xiv. ed.: almási t. – blazovich l. – géczi l. – kőfalvi t. – kristó gy. szeged – budapest: jate, 1990-2004 ann. burgh. = annales burghausenses. in: pertz g. h. (ed.) monumenta germaniae historica. scriptores. xxiv. hannoverae: hahn, 1866. pp. 61-62 ann. cist. in hein. = annales cisterciensium in heinrichow. in: pertz g. h. (ed.) monumenta germaniae historica. scriptores. xix. hannoverae: hahn, 1866. pp. 543-547 ann. mat. = annales matseenses. in: pertz, g. h.: monumenta germaniae historica. scriptores. ix. hannoverae: hahn, 1851. pp. 823-835 annales mellic. = annales mellicenses. in: pertz g. h.: monumenta germaniae historica. scriptores. ix. hannoverae: hahn, 1851. pp. 480-501 ann. mellic. cont. zwetl. ter. = annales mellicenses continuatio zwetlensis tertia. in: pertz g. h.: monumenta germaniae historica. scriptores. ix. hannoverae: hahn, 1851. pp. 654-669 ann. zwetl. = annales zwetlenses. in: in: pertz g. h.: monumenta germaniae historica. scriptores. ix. hannoverae: hahn, 1851. pp. 677-684 anon. leob. chron. = anonymus leobiensis chronicon. ed.: zahn j. graz: leuschner & lubensky, 1865 chron. aul. reg. = chronicon aulae regiae. in: loserth j.: fontes rerum austriacarum. vol. 1. 8. wien: in commission bei k. gerold’s sohn buchhändler der kaiser akademie der wissenschaften, 1875 chron. austr. = chronica austriae. in: lhotsky a.: monumenta germaniae historica. scriptores rerum germanicarum nova series. xiii. berlolini, turici: weidmann, 1967 chron. de gest. prin. = chronica de gestis principum. in: in: pertz g. h.: monumenta germaniae historica. scriptores rerum germanicarum. xix. hannoverae: hahn, 1866. pp. 47-106 cont. canon. s. rud. salis. = continuatio canonicorum s. rudberti salisburgensis. in: wattenbach w..: monumenta germaniae historica. scriptores. ix. hannoverae: hahn, 1851. pp. 819-823 dl = archives of diplomatics (hungarian national archives, collection of medieval charters) hain g. = hain gáspár lőcsei krónikája. ed. bal j. – förster j. – kauffmann a. lőcse [levoča]: reiss ny., 1910-1913. mart. meist. ann. gorl. = martinus meisterus. annales goerlicenses. in: hoffmann c. g.: scriptores rerum lusaticarum antiqui et recentiores. 1. / 2. lipsiae – budissae: david richter, 1719 references alexandre p. 1987. le climat en europe au moyen age. contribution à l’histoire des variations climatiques de 1000 à 1425, d’après les sources narratives de l’europe occidentale. paris: école des hautes études en sciences sociales. 825 p. brázdil r. – kotyza o. 1995. history of weather and climate in the czech lands. i. period 1000-1500. zürcher geographische schriften 62. zürich: geographisches institut eth. 260 p. brázdil r. – pfister c. – wanner h. – von storch h. – luterbacher j. 2005. historical climatology in europe – the state of the art. climatic change 70(3): 363-430 büntgen u. – esper j. – frank d. c. – nicolussi k. – schmidhalter m. 2005. a 1052-year tree-ring proxy for alpine summer temperatures. climate dynamics. 25/2-3. 141-153 büntgen u. – frank d. c. – nievergelt d. – esper j. 2006. summer temperature variations in the european alps a. d. 755-2004. journal of climate 19: 5606-5623 büntgen u. – frank d. c. – grudd h. – esper j. 2008. longterm summer temperature variation in the pyrenees. climate dynamics 31(6): 615-631 glaser r. 2001. klimageschichte mitteleuropa. 1000 jahre wetter, klima, katastrophen. darmstadt: primus verlag. 227 p. grynaeus a. 2003. dendrochronology and environmental history. in: laszlovszky j. – szabó p. 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(eds.) medievisztikai tanulmányok. a iv. medievisztikai phd konferencia előadásai. szeged: szegedi középkortudományi könyvtár. pp. 135-142 sági k. 1968. a balaton vízállás-tendenciái 1863-ig a történeti és kartográfiai adatok tükrében. veszprém megyei múzeumok közleményei 7: 441-464 shabalova m. v. – van engelen a. f. v. evaluation of a reconstruction of winter and summer temperatures in the low countries, ad 764-1998. climatic change 58(1-2) 219-242 sümegi p. – jakab g. – persaits g. – törőcsik t. – csökmei b. – náfrádi k. 2005. a kaszói baláta-tó középkor végi és újkori fejlődéstörténete történeti ökológiai, környezettörténeti vizsgálatok alapján. in: kázmér m. (ed.) a környezettörténet 2006 konferencia előadásainak összefoglalói. budapest: hantken kiadó. pp. 46-47 yan z. – alexandre p. – demarée g. 1999. narrative warm/cold variations in continental western europe, ad 708-1426. science in china. series d 40(5): 509-517 journal of environmental geography 5 (1–2), 1–10. meander cores on the floodplain – the early holocene development of the low-floodplain along the lower tisza region, hungary tímea kiss * , péter hernesz, györgy sipos department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: kisstimi@gmail.com abstract the aim of the present study is to analyse the morphology, sedimentary structure and age of flood-free islands on the low-floodplain of the lower tisza in order to determine the date and causes of river incision. on the study area the identified 16 elevated surfaces were divided into two groups. the real or meander core floodplain islands appear in the northern and central units of the study area. they are characterized by steep slopes, elevated surface and small territory (2.1 km 2 in average). the second type consists of elevated surfaces of point-bar systems and natural levees of paleo-channels, and they mostly appear in the southern unit. they have gentle slopes, smaller relative height and greater area (4.1 km 2 in average). the spatial distribution of the two types refers to slow and slight tectonic uplift in the northern part of the study area, though in the south they refer only to the lack of sinking. the results of the sedimentological analysis on the meander core at szegvár show that it originally belonged to the high-floodplain. due to the slight tectonic uplift the meandering channel incised into the soft sediments, and as lateral erosion was possible, an ingrown-type meander developed, which later as a result of cut-off has become a meander core (or umlaufberg). based on the osl data the incision started at least 20.1±2.1 ka ago, and it terminated ca. 8-9 ka ago. the calculated bankfull discharge of the szegvár paleo-meander is estimated to be 4000-7500 m 3 /s, referring to a considerably higher discharge than that of the present-day tisza (800 m 3 /s). similar planimetric meander parameters of paleo-channels on the high and low-floodplain suggest that the incision was not driven by climate, i.e. discharge change but primarily by tectonic movement. this is also supported by the height condition of the islands, as their surface is almost at the level of the high-floodplain. keywords: floodplain formation, incision, ingrown meander, floodplain island, osl dating introduction the floodplain of the tisza river south of csongrád (hungary) was formed at the late pleistocene and holocene through the alteration of erosional and aggradational activities along the river. the most i mportant event in its development history was an incision, which resulted in the differentiation of the low and high-floodplain. according to láng (1960) and mezősi (1983) this can be dated to the beginning of the holocene, approximately 12 ka ago, when the tisza and maros rivers incised into the former floodplain by ca. 10-12 m. they explained the process by an increased erosional activity, however the causes of i ntensified fluvial activity were not resolved. according to mátyus (1968) the incision occurred later, in the boreal phase and it resulted in the development of a 3-5 km wide floodplain. however, lovász (2002) contested this idea as he claimed that the amount of precipitation had decreased in the boreal phase, consequently run-off and fluvial processes became limited. based on the paleo-discharge data of gábris (1985, 1986) the discharge of the rivers was mush higher (up to 10 times) in the preboreal and atlantic phases, which could also explain the intensive incision. according to gábris (1995), the development of the low-floodplain is a rather new process (ca. 40005000 y), and overbank accumulation had also started recently, ca. 2.5 ka ago. the explanation of the incision and subsequent aggradation just by climatic causes has several week points. the area is quite active tectonically: the area of szeged is the most intensively subsiding area of the great hungarian plain since the beginning of the neogene (borsy, 1990). based on the lack of overbank aggradation, however, somogyi (1967) supposed the termination of sinking since the end of the pleistocene, or even since the beginning of the riss-würm interglacial. nevertheless, present-day measurements (joó, 1998) on vertical tectonic movements indicate intensive subsidence (3-4 mm/y) in the southern part of the lower tisza region, especially at the city of szeged, at the confluence of the tisza and maros rivers. another centre of the sinking is at the middle tisza region, where the rate of subsidence is similar to that experienced along the lower tisza. in between the two sinking areas, in the northern part of the lower tisza region tectonic movements have a lower rate, and thus the area is relatively up-lifted. however, timár (2003) emphasizes, that the intensive exploitation of subsurface waters, natural gas and oil might also cause surface subsidence, thus the present-day rate of tectonic movements should not projected to longer periods. consequently, no precise data exist on quaternary vertical movements, but the tectonic activity is clearly indicated by the fluvial forms on the low-floodplain. in case of subsidence overbank aggradation becomes dominant, which can also hide previous forms (twidale, 1964). in case of uplifting fluvial erosion intensifies, causing incision and subsequent lateral erosion on the former floodplain. hence, meander cores can develop on the low-floodplain as the result of (ingrown) incised meander development (fairbridge, 1968), and the promailto:kisstimi@earth.geo.u-szeged.hu 2 kiss et al. (2012) cess can also separate the low and high floodplains (gábris, 1995). incised meanders have two types: ingrown and entrenched (morisawa, 1985), both developing as a result of tectonic uplift (twidale, 1964). in case of entrenched meanders incision is quick and meander development usually reaches the solid rock bed, while ingrown meanders develop usually at a slower incision rate when lateral and vertical erosion can coexist. as the result of lateral erosion the meanders can be cut off, which results in the development of meander cores being much higher than the alluvium. meander cores are cited in different ways in the literature: pembina (fairbridge, 1968), bedrock spur or natural arch (summerfield, 1991; hugett, 2007), umlaufberg (mahaney, 1984). as incision and lateral erosion coexist, the cross-section of the valley is asymmetric: the convex side of the meander has gentler slope and on the slip-off face indications of pointbars might appear (fairbridge, 1968). meander cores of ingrown meanders appear on the low-floodplain of the lower tisza region. until the 19th century river regulation works they were flood-free surfaces surrounded by marshlands, therefore in earlier researches these elevated surfaces were cited as floodplain islands, flood-free islands, terrace-islands or pleistocene remnant surfaces (mátyus, 1968; andó, 1969; mezősi, 1983). the meander cores can be the key to the reconstruction of the first stages of the development of the lower tisza region. the aim of the present study is to identify and classify the flood-free islands of the low-floodplain, to determinate the date of incision and its causes in the lower tisza region by studying the morphology, sedimentary structure and osl age of meander cores. fig. 1 main geomorphic features of the lower tisza region (a) the meander cores near szegvár were studied in detail (b) a) elevated surface, b) paleo-channel, c) artificial floodplain, d) alluvium, e) lake, sz1-2 sampling sites meander cores on the floodplain – the early holocene development of the low-floodplain along the lower tisza region, hungary 3 study area the research was carried out on the low-floodplain of the lower tisza region (territory: 1214 km 2 ) between csongrád and the hungarian state border (fig. 1a). the border between the low and high-floodplain is quite pronounced (1-5 m) on the northern part of the study area (north of the line between hódmezővásárhely and dóc), though on the southern part it is less striking (0.5-2 m) (kiss and hernesz, 2011). most of the low-floodplain was annually flooded until the 19th century river regulation works (kiss et al., 2011) therefore it is covered by young overbank sediments (marosi and somogyi, 1990). based on the geomorphic features of the low-floodplain, the study area could be divided into three units (kiss and hernesz, 2011). the northern unit (north of the csongrád-szentes line) has an elevated edge (3-5 m), it gets narrower towards the south (average width: 13.3 km) and paleo-channels and point-bar systems cover its surface. the central unit (north of the hódmezővásárhely-sándorfalva line) is the narrowest (average width: 8.1 km), though its edge is quite sharp (3-5 m). in the central unit scour channels (breaches) and back-swamps are the dominant fluvial forms, indicating limited lateral migration. the southern unit is the widest (average width 24.8 km) and least marked (1-1,5 m in the east and 1-3 m in the west). its eastern part is covered by paleo-channels and welldeveloped point-bar systems, however its rim is not well defined as the alluvial fan of the mar os stretches into it. the western part of the southern unit is poor in fluvial forms, as its surface is covered by 3 -5 m thick pleistocene loess (miháltz, 1967; mátyus, 1968). therefore, mostly based on bio-geographical evidences deák (2010) excluded this part of the lowfloodplain. in this case the average width of the southern unit is only 10-15 km, and its western edge is only 1-2.5 m high. methods a digital terrain model (dtm) was created based on topographical maps (scale 1:10.000), using arcgis 10. on the dtm the floodplain islands were identified, their rims and forms, and the neighbouring p aleo-channels were localised. the morphomertric p arameters of the islands were calculated (area, maximum width and length, mean relative height over the low-floodplain and mean height difference from the closest high-floodplain), and also the mean height of the low and high-floodplain in the vicinity of the floodplain islands were determined. the radius of curvature, width and meander length of the paleo channels embracing the islands were also measured, and based on these horizontal parameters the p aleodischarge of the channels were determined using the equations of timár and gábris (2008). on the meander core near szegvár (fig. 1b) two corings (400 cm deep) were made. the sz1 coring was established on the bank of the paleo-channel, the sz2 coring was made on the slip-off surface of the island, on the remnants of its former point-bar (fig. 5a). the grain-size distribution of the samples was determined by fritsch analysette 22 laser equipment with a measurement range of 0.08-2000 μm. samples underwent ultrasonic homogenisation and all measurements were repeated three times to check if there is further disintegration. grain-size classes were determined using the udden scale. the age of samples was determined by optically stimulated luminescence (osl). from the sz1 and sz2 corings four and three osl samples were collected, respectively. due to the inadequate amount of medium sand in the samples fine grains (4-11 μm) were separated and dated. although fluvial sediments are examined usually by using the coarse grain method (rittenour, 2008), we found earlier that in a medium energy environment fine grain mean and coarse grain minimum ages are fairly well corresponding (sipos et al., 2010) in the area. nevertheless, based on the measurement of fresh, known age point bar sediments along the tisza river, ages derived from silty deposits may overestimate the true age by 0.5-1.0 ka (kovács, 2011), which has to be considered. the carbonate and organic content of the sa mples were removed by hcl and h2o2. finally samples were treated in hexafluoro-silicic acid to remove feldspars and to receive the quartz fraction of the sample. samples were settled on aluminium discs from an acetone suspension. measurements were made on a risø tl/osl da-15 automated luminescence reader using the single aliquot regeneration (sar) protocol (wintle and murray, 2006). presence of residual feldspar was monitored using the osl/ir depletion ratio (duller, 2003). pre-heat tests were carried out in the 190-280 °c range, all samples yielded 220 °c as the suitable preheat temperature for the osl measurements. in situ gamma and cosmic dose rate was measured by a canberra inspector 1000 portable nai gamma spectrometer during sampling. alpha and beta dose rates were determined on the basis of u, th and k contents measured by a ca nberra-type laboratory gamma spectrometer equipped with a low background coaxial ge detector. alpha efficiency was taken 0.1, wet dose rates were calc ulated on the basis of in situ water contents. 4 kiss et al. (2012) results and discussion morphometry of the floodplain islands on the study area altogether 16 elevated surfaces were identified on the low-floodplain. these floodplain islands were divided into two groups based on their morphology and origin: (1) meander cores and (2) the high point-bars and natural levees of the paleo-meanders. the first group of islands have sharp rims and were eroded on some sides by paleo-channels. the mean territory of these islands is 2.1 km 2 . the largest (6.3 km 2 ) is located near szegvár (no.3), and was studied in detail, whilst the smallest (0.1 km 2 ) is in its close vicinity (no.2). these islands are slightly elongated, as their average length/width ratio is 2.4. on their slip-off slope point-bars remnants of could be identified. their edge is well-defined (fig. 2), since they are laterally eroded by subsequent paleo-channels. the size of these paleochannels (mean rb= 996 m) is much greater than that of the present-day tisza (mean rb= 600 m). the average height of meander cores is 81.3 m asl, the highest (83.6 m asl) is the northernmost one near magyartés (no.1), and the lowest (79.2 m asl) can be found in the southern unit, near maroslele (no.13). the relative height of the islands compared to the lowfloodplain is 2-4 m. the highest ones (no.1 and 15) has a relative height of 4.1 and 4.0 m, though the lowest (no.13) is also 2.2 m above the low-floodplain level. their height reaches or in some cases exceeds the height of the neighbouring high-floodplain. for example the island at szőreg (no.15) is inhabited since the neolithic period (since ca. 6500 bp) as the flood-free are provided good circumstances for settlement, and also a 12-13th c. monastery was built on it (trogmayer, 1977). thus the surface of the meander cores could be further elevated as a consequence of human activity. these meander core islands appear mostly in the northern and central units of the lower tisza region, and only two of them (no.15 and 16.) are located in the southern unit. the second type of floodplain islands consist of elevated point-bars and natural levees of the paleochannels, thus their rims are not well-defined. the average area of these islands is 4.1 km 2 , the largest (16.2 km 2 ) is the extensive point-bar system of the hód-tó paleo-channel (no.9), and the smallest (0.4 km 2 ) is island no.14. their form is elongated, the greatest length/width ratio is 4.5 (no.7), which is connection with their fluvial origin. on their surface 1-2 m height differences appear, showing the location of point-bar ridges and swales (fig. 3). the highest (80.6 m asl) of them is near dóc (no.6), while the smallest (78.9 m asl) is near the gyuló paleo-channel (no.10). their height compared to the level of the low-floodplain is smaller than of the first island group, as the highest (no.6) and lowest (no.8) representatives are 3.2 m and 1.3 m high, respectively. their surface is much lower (79-80.5 m) than the level fig. 2 the cross-sectional profile of island no.1 showing the eroded rims and slip-off face with the remnants of point-bars fig. 3 the cross-section of island no.6, representing an elevated (2-4 m) point-bar system, where the brink-line of the point-bars is almost as high as the high-floodplain meander cores on the floodplain – the early holocene development of the low-floodplain along the lower tisza region, hungary 5 of the high-floodplain. they appear along those paleochannels (e.g. hód-tó, gyúló-ér, deszk, tiszasziget), which had quite high bankfull discharges. their radius of curvature (570-3200 m) is 2.5 times greater than of the present-day tisza (fiala and kiss, 2006). they mostly appear in the southern unit of the study area, where these paleo-channels remained the two island types have characteristic spatial distribution (fig. 4a). in the northern and central units of the study area islands are much higher than the lowfloodplain and their surface is almost at the same level as of the high-floodplain. their steep rims are well defined. their similar height to the high-floodplain indicates that they can be defined as meander cores, and they are relatively young features as they were not eroded (andó, 1969). in contrary, the point-bar and natural levee islands appear along the paleo-channels in the southern unit of the study area. these elevated surfaces have smaller relative height and gentle slopes. the spatial distribution of these two island types explains some details of the development history of the region. the meander cores refer to slow incision, whilst the point-bar and natural levee islands indicate lateral floodplain aggradation, where the subsequent overbank accumulation terminated or became very slow, as the forms are not buried by fluvial deposits, and the surface is not evened out. fig. 4 location and type of floodplain islands and their relative height a) location of floodplain islands: a) meander cores, b) elevated point-bars and natural levees of paleo-channels, c) pleistocene loess blanket, no.1: magyartés; no.2: tétel-hát, no.3: szegvár, no.4: ányás i., no.5: ányás ii., no.6: dóc, no.7: körtvélyes, no.8: solt, no.9: hód-tó, no.10: gyúló-ér, no.11: nagyfa, no.12: batida, no.13: maroslele, no.14: lebő-halom, no.15: szőreg, no.16: tiszasziget; b) relative height of islands compared to the low-floodplain.; c) and to the high-floodplain 6 kiss et al. (2012) the spatial distribution of the height condition of floodplain islands the relative height of island surfaces compared to the high and low floodplains reflects the tectonic activity during and after their development. the height conditions of the western and eastern high-floodplain surfaces are not similar, thus the height of the floodplain islands was compared to the closest high-floodplain surface. the relative height of the floodplain islands (calculated from the level of the lower floodplain) decreases towards the south (fig. 4b), though this tendency is broken by some islands, as islands no.6 and no.15 are slightly higher and no.7 and 8 are lower. in case of island no.6 this can be explained by the surrounding deeper-lying paleo-channels, resulting a relatively greater height value, whilst in case of island no.15 (at szőreg) this can be explained by anthropogenic activity (trogmayer, 1977). the smallest height difference between the lower floodplain and floodplain islands was found in case of the islands no.7 and 8 (at körtvélyes and dóc), which are higher than the lower floodplain only by 1.3 and 1.5 m, respectively. the highest islands (over 3.0 m) mostly appear in the northern and central units of the study area, whilst the smallest ones (under 2.5 m) are located in the southern unit, south of the line between hódmezővásárhely and dóc. the height of islands compared to the closest highfloodplain surface refers to their evolution: supposing that the present-day high-floodplain was the former floodplain of the tisza (mezősi, 1983), the surface of islands represents the same level. these forms were formed during the incision of the river into the highfloodplain and simultaneous development of the lowfloodplain the mean height of the islands was extracted from the mean height of the high-floodplain (fig. 4c). only one negative data was measured (no.1, magyartés): here the island is higher than the high-floodplain by 0.25 m. towards the south the islands no.1-8 are almost as high as the high-floodplain (they are lower only by 0.5-0.9 m). the next island (no.6) is unique, considering its height conditions, as it is much higher than the low-floodplain (3.2 m) despite of its great difference (3.1 m) from the neighbouring high-floodplain (reason i explained earlier). going south the height difference between the high-floodplain and islands surfaces increases (1.0-1.5 m) which can be explained by the different origin of the islands (point-bar systems and natural levees). island no.13 (at maroslele) and island no.15. (szőreg) are the only exceptions being only 0.7-0.8 m lower than the high-floodplain. based on relative height conditions, islands in the northern and central parts are much higher, and are at the same level as the high-floodplain. meander cores in the northern unit imply an uplift process resulting incision and the development of ingrown meanders. on the contrary, islands in the southern part of the study area are less elevated, and the southern unit is a low lying alluvium, however, sinking could not be characteristic or could not last long, as overbank sedimentation did not cover the floodplain forms. all these suggest that the southern part of the study area developed in a different way than the northern and central parts. detailed analysis of the no.3 meander core near szegvár the area of this meander core is 6.3 km 2 , its greatest width is 2.0 km and greatest length is 3.2 km (fig 5a), its mean height is 81.9 m asl, its highest point is at 85 m asl. its north-eastern rim is quite steep, it was laterally eroded by the kurca brook. on the other sides of the form rim is well defined, though it has more gentle slopes. the surface of the studied meander core is not uniform, as the rims are dissected by gullies and on its slip-off surface the fragments of point-bars left behind by incising paleo-meander can be identified (fig. 5b). the paleo-channel dividing the high-floodplain and the surface of the meander core is wide (300-500 m), the length of the palaeo-meander is ca. 5-7 km. based on its morphometric parameters, paleo-discharge (4000-7500 m 3 /s) was much higher than that of the present-day tisza (800 m 3 /s). in this paleo-meander a smaller misfit channel of the kurca brook can be identified. fig 5 the digital elevation model of floodplain island no.3 at szegvár, the location of corings (a) and the cross-section of the meander core (b) meander cores on the floodplain – the early holocene development of the low-floodplain along the lower tisza region, hungary 7 the neighbouring high-floodplain (82.9 m asl) is ca. 4 m higher than the low-floodplain (78.7 m asl), the arched rim in between is well defined as it was laterally eroded by the paleo-channel. the surface of the highfloodplain is dissected by the headward erosion of some channels (i.e. kórógy brook). the high-floodplain probably has not been reached by floods as early as the beginning of the holocene, thus in the neolithic period a continuous settlement could be established on the top of the rim, as it is indicated by the neolith tell of szegvár-tűzköves dated back to 6.87.1 ka (korek, 1987). but the paleo-channel beside the tell and around the meander core remained a swampy area until the late 19 th c. river regulation works (on old maps it was indicated as kontra lake). two corings were made in order to analyze the meander core from a sedimentological aspect. the sz1 coring was made on the bank of the paleo-channel, approx. 100 m far from the rim of the meander core. in the whole profile clay and silt are dominant. in the lower zone (230-370 cm) clay content (ca. 60 %) overwhelms the silt content (ca. 30 %) (fig. 6). in the middle zone (110-230 cm) the clay content increases further with three well-defined peaks. in the uppermost zone (0-110 cm) the silt becomes dominant (over 60 %). fine sand (under 0.06-0.125 mm) appear only occasionally (at 180-190 and 230-240 cm), but its proportion is never over 2 %. results suggest, that these sediments were deposited at low energy conditions: probably the profile represents the loessy overbank deposits (or channel infill) of the paleo-channel. from sz1 zone i. and ii. four osl samples were taken (table 1). the oldest sample (190-200 cm) is 16.9±1.7 ka, while the youngest (150-160 cm) is 15.7±1.5 ka old. thus, the overbank or channel-infill sediments of the lower part of the profile were deposited around 15-17 ka ago at the end of the ságvárlascaux interstadial or at the beginning of the oldest dryas (the geological times scale compiled by gábris (2003) was applied). the sz2 coring was made on the slip-off face of the meander core on the top of a remnant point-bar. in the lower zone of the profile (390-420 cm) sand fraction is dominant (55-60 %), the proportion of silt (2637 %) and clay (6-7 %) is smaller. in the middle zone (180-390 cm) four peaks of the sand fraction appear (at the depth of 350-380, 300-340, 240-280 and 180-210 cm), but the proportion of sand in the peaks is co ntinuously decreasing from 48.8 % to 15.5 %. at the same time the amount of silt is increasing (from 26.4 % to 70.2 %). in the upper zone (0-180 cm) the sand almost disappears and clay becomes dominant (over 60 %) overtaking silt (ca. 30 %), similarly to coring sz2. in the lower and middle zones the sand peaks refer to fig. 6 grain size distribution of the two corings (sz1 and sz2) and the depth of osl samples 8 kiss et al. (2012) near-bank deposits, which were deposited during high energy conditions. these were covered by suspended sediments at falling stage or at smaller floods. the samples of the upper zone represent overbank floodplain sediments. osl dating was carried out on three samples of coring sz2. the lowest sample (400-410 cm) probably represents the active point-bar, the sandy samples at 310-320 cm stand for near-bank deposits, whilst the fine grain dominated zone at 150-160 cm correspond to overbank floodplain sediments (fig. 6, table 1). the age of the active point-bar, 20.1±2.1 ka, dates back to the late glacial maximum. the accumulation of the nearbank deposits took place at 18.1±2.1 ka, in the ságvárlascaux interstadial. the clayey-silty overbank sediments accumulated 14.4±1.3 ka ago, thus it was deposited simultaneously with the youngest samples of coring sz1 – considering their error intervals. based on the morphological, sedimentological and osl data of meander core no.3 at szegvár the incision of the paleo-meander was already in progress in the late pleniglacial. the river laterally eroded the present-day edge the high-floodplain slowly and deposited its sandy point-bar on the slip-off surface of the meander core. this result fits to the findings of domokos and krolopp (1997), who made a sedimentological and paleontological study on a sandy deposit on the high-floodplain. they found fluvial sandy deposits covered by 16-18 ka old loess. this reinforces our data, as the point-bar and near-bank sandy layers of the studied paleo-channel are 18.1-20.1 ka old, thus this meander probably indicates the very beginning of the incision process. the over-bank (or channel infill) loessy-silty sediments of the corings date back to 14.4±1.3 and 16.9±1.7 ka, thus by this time incision was significant, and only overbank sediments were deposited on the surface of the meander core. the age of these sediments correlates well to the results of krolopp et al. (1995), studying the loess blanket west of szeged, and finding that the loessy cover over the fluvial sediments was deposited ca. 13-25 ka ago. conclusions two types of floodplain islands were identified in the lower tisza region. the real or meander core floodplain islands are characterized by steep slopes, elevated surface (higher than 80.5 m) and small territory (2.1 km 2 in average), and they appear in the northern and central units of the study area. they were identified as meander cores of earlier paleo-channels. the second type consists of elevated surfaces related to point-bar systems and natural levees of paleo-channels. they are characterized by gentle slopes, smaller relative height (under 2.5 m) compared to the low-floodplain and greater area (4.1 km 2 in average), and they mostly appear in the southern unit. the spatial distribution of the two types of floodplain islands can be explained by the different evolution of the floodplain. the development of meander cores in the northern and central units refer to slow and slight tectonic uplift, though in the southern unit the existence of higher fluvial forms of old paleo-channels refer to the lack of sinking, otherwise they would be covered by overbank sediments. this result is in contradiction with the present-day rate of sinking (joó, 1998), but this disagreement could be explained by the intensive subsurface natural oil, gas and thermal water extraction causing subsidence (timár, 2003). the results at the meander core at szegvár are corresponding well to the data of earlier sedimentological analyses carried out on the high-floodplain (domokos and krolopp1997), and prove that the meanader cores are remnant surfaces of the high-floodplain. the age (14.4±1.3 ka to 16.9±1.7 ka) of the loessy overbank sediments covering the meander core date back to the oldest dryas, when fluvial loess deposited intensively in the area (sümegi and krolopp, 1995; szöőr et al., 1991). due to the slight tectonic uplift the meandering channel incised into the soft sediments, and as lateral erosion was possible, an ingrown meander developed, which turned to be a meander core following a cut-off event. the osl age of the uppermost point-bar of the table 1 dosimetry, equivalent dose and osl age data of the investigated silt samples site sample depth (cm) water content (%) u-nat (ppm) 232 th (ppm) k (%) d'α+β (gy/ka) d’in situ (gy/ka) d’total (gy/ka) de (gy) osl age (ka) sz1 osz584 150-160 18 ± 1.8 1.79 6.78 1.31 1.83±0.24 0.89±0.04 2.00±0.24 36.99±1.44 15.7±1.5 osz586 190-200 24 ± 2.4 1.64 7.28 1.36 1.74±0.22 0.89±0.04 1.91±0.23 38.57±2.06 16.9±1.7 osz587 240-250 24 ± 2.4 1.94 7.25 1.49 1.90±0.25 0.78±0.03 2.07±0.25 37.66±2.10 16.2±1.8 osz588 280-290 25 ± 2.5 1.91 7.67 1.42 1.86±0.24 0.78±0.03 2.03±0.24 36.61±1.90 16.0±1.7 sz2 osz590 150-160 13 ± 1.3 1.72 6.1 1.07 1.70±0.22 0.84±0.04 1.87±0.22 31.73±0.83 14.4±1.3 osz594 310-320 15 ± 1.5 1.55 5.75 0.92 1.49±0.19 0.74±0.03 1.66±0.19 35.13±3.37 18.1±2.4 osz597 400-410 17 ± 1.7 1.2 4.2 0.78 1.15±0.15 0.57±0.02 1.32±0.15 30.21±2.36 20.1±2.4 meander cores on the floodplain – the early holocene development of the low-floodplain along the lower tisza region, hungary 9 ingrown paleo-channel indicates that the incision started at least 20.1±2.1 ka ago. however, the last activity phase of a paleo-channel (at kenyere brook) on the high-floodplain was dated back to only 11.5±0.8 ka (sipos et al., 2010). the incision terminated at 8-9 ka ago, as a huge paleo-meander near deszk remained well preserved on the low-floodplain, and it was forming its youngest point bars at 8.9±0.6 ka ago (sipos et al., 2010). the incision was probably a rapid process. it lasted only for 1-2 ka, as the radius of curvature of paleochannels on the high-floodplain and at the feet of the meander cores is similar. the rapid incision is also supported by the similar osl ages of point-bars of the paleo-channels on the highand low-floodplain (sipos et al., 2010). the calculated bankfull discharge of the paleomeander at szegvár was 4000-7500 m 3 /s, referring to a considerably higher discharge than that of the presentday tisza (800 m 3 /s). this discharge is similar to the discharge of the paleo-meander on the low-floodplain near deszk (7000 m 3 /s) but lower than the paleo-channel (12.700 m 3 /s) along the kenyere brook on the highfloodplain (sipos et al., 2010). the similarity in the horizontal morphometric meander parameters of paleochannels on the high and low-floodplain suggest that the incision was not driven by climate change but primarily by tectonic movement. it is also supported by the height condition of the meander cores, as their surface is almost at the level of the high-floodplain. consequently, the northern and central units of the study area were characterized by slight tectonic uplift in the late glacial or early holocene periods, resulting slow incision. in contrary the southern unit was lower lying, less active tectonically, and subsidence was probably not characteristic until nowadays. acknowledgements the research was supported by the 100761 otka research found and huro/0901/266/2.2.2 project references andó, m. 1969. az alsó-tiszavidék. in: pécsi m. 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kiss, 2009; vermes and pálfai, 2007). in medieval hungary direct information on drought events is available only in a few cases. these few cases, however, may provide precious examples on how severe droughts effected late medieval socioeconomic conditions, and also on the society's reaction (e.g. weak harvest, tax reductions, special actions/permissions of authorities, effects on military operations). they become even more apparent when comparing to other countries, for example, in the central european region. another interesting point is that most of the known medieval drought events appeared in combination with other reported natural hazards (e.g. heat and devastating hails: 1507, locust invasion: 1474–1479). in the recent decade regional overviews, including the middle ages were published concerning the czech lands (brázdil et al., 2013), germany (included in: e.g. glaser, 2008), for the eastern alpine region (included in: rohr, 2007 – medieval extremes). for the last 500 years, for example, in the discussion of low water levels of the upper-rhine by pfister et al. (2006) in switzerland, or about the droughts occurred in spain (e.g. domínguezcastro et al., 2008). in the context of a famous historical drought, recently the most well-known early modern case, the 1540 drought event – which otherwise was also combined with great heat – was discussed on a european scale (wetter et al., 2014). the term 'drought,' with clearly indicating serious water deficit for a longer period of time, can sometimes have slightly different meanings: meteorological drought, hydrological drought, agricultural and socio-economic drought have their own definitions in the different disciplines (e.g. heim, 2002; pálfai, 2004; brázdil et al., 2013). in historical documentary evidence one can often find descriptions referring to drought either in its agricultural drought (i.e. affecting harvest and food production), or in its hydrological drought (i.e. referring to conditions of water bodies, e.g. groundwater level in wells, water levels of lakes/water flows) meanings. due to its importance in food supply, agricultural drought usually plays an important role in historical documentation (e.g. 1362, 1507 in our present cases), but hydrological drought – with problems in using (or not being able to use) major water flows (1494) or in military operations (e.g. 1474, 1479, 1494) as well as shortage of water supply (1362, 1507) – can also rather often appear in historical documentation. socio-economic consequences of great droughts can be followed practically in all of our five studied cases. henceforth, despite relatively scarce documentation on the topic, we can clearly identify some extraordinary great drought events in the countries of the hungarian crown; such cases were, for example, documented in 1362, 1474, 1479, 1494 and 1507. the inclusion of the 12 kiss and nikolić (2015) later date (1507) in discussion is due to the hungarian termination of the end of the middle ages (1526). these occurrences are also interesting because reports about the five great drought events remained at least in four different sources types: while the 1362 and 1494 cases are preserved in charters, the 1474, 1479 and 1494 examples remained in a contemporary chronicle, the 1507 great drought event (and some of its consequences) was reported as contemporary inscriptions in an almanach (notes of a buda citizen), and an extensive set of information was also included in an economic-administrative source, the account books of the bishop of eger (his administrator's accounts). thus here, as a first paper on the topic, examples are provided when clearly great drought events were reported in contemporary medieval documentation. late medieval droughts and dry spells in central europe and beyond for the better understanding of the studied cases, it is worth to have an overview on the medieval–late medieval dry spells and droughts known from the surrounding areas. due to the fact that some studies and published evidence in this topic are already available for the eastern alpine region, the czech lands and for poland, it is also possible to discuss some parallels between the carpathian basin and its immediate neighbourhood. in the eastern alpine region, based mainly on contemporary narratives and partly also on other (e.g. charter) evidence, some of the years with droughts or longer dry spells and water deficit (often combined with mentioning heat), documented in 13th–early 15th-century reports, were included in the book of christian rohr (2007) 1244, 1255, 1262, 1276, 1277, 1307, 1311, 1312, 1313, 1360, 1394, (1401, 1356, 1425 – suggested by glaser, 2008), 1426, 1427, (1473 – suggested by brázdil and kotyza, 1995) 1503, 1513, 1514. in case of austria, drought in reports is often combined with an extensive loss of domestic animals, for example in 1277, 1360, 1394, 1426, 1427, while sometimes drought is followed (or accompanied) by reports on food shortage or hunger (e.g. in 1255 in austria, or in 1312, 1313 in the czech lands, austria and bavaria (e.g. brázdil and kotyza, 1995; rohr, 2007) as well as urban fires (e.g. 1244 in austria: rohr, 2007). it is interesting to conclude that, concerning our discussed late medieval drought events, currently we find almost no parallels in known medieval austrian documentation (only 1473: on year earlier than reported for hungary). in the czech lands, based on various types of contemporary source evidence, shorter or longer periods of dry weather and/or drought events were identified in the following years: 1091, 1121, 1128, 1177, 1194, 1252, 1260, 1262, 1266, 1283, 1307, 1312, 1315, 1326, 1328, 1333, 1334, 1337, 1348, 1352, 1368, 1369, 1371, 1393, 1423, 1425, 1432, 1441, 1442, 1461, 1469, 1471, 1473, 1476, 1480, 1482, 1501, 1503, 1504, 1506, 1509, 1512, 1513, 1516, 1517, 1518, 1520, 1525 (see brázdil and kotyza, 1995; brázdil et al., 2013: table 1 and fig. 3). in the czech lands, with regards to our study period, especially the 1500s and 1510s stand out with 5-5 years of considerable dry periods reported in a single decade, while the 1260s, 1330s and the 1470s with 3-3 cases per decade are also rather significant. this list, containing any dry-weather information found by the authors concerning the middle ages, provides further information concerning our examples: in connection with the listed drought years in hungary and croatia, it seems that 1473 and 1506 (thus, one-one year before our great drought events), and 1480 (one year after our great drought case) were reported as years with dry spell or drought in the czech lands. according to the weather event data collection for poland (containing references up to 1500: malewicz, 1980) based on narrative evidence dry spells, droughts or low water levels were documented concerning the years 1322, 1332, 1361, 1379, 1442, 1448?, 1451, 1452?, 1455, 1459, 1461, 1463, 1467, 1468, 1469, 1473, 1474, 1475. however, from a contemporary report (by marcin biem) it is also clear that 1494 was an important drought year, too (limanówka, 2001). thus, based on the currently available medieval polish evidence the 1450s, 1460s and 1470s have the most importance; and the year of 1361, and both 1474 and 1473, 1475 (i.e. the years before and after) are also mentioned as years with significant droughts. both from the viewpoint of dalmatia, croatia and hungary, documentation related to the central and east-mediterranean areas of europe (or the region east to us) would have great further importance. however, no studies have been carried out so far on the italian) droughts, and we find no parallels of the discussed events in the greek medieval weather-related investigations either (e.g. telelis, 2008). as we can see, the years with shorter or longer dry periods, discussed in the present study, sometimes have parallels in the neighbouring areas, but in most cases currently there are no direct parallels known from the areas closest to the carpathian basin. nevertheless, this is also true when comparing the available documentary evidence of the neighbouring areas to each other. on the one hand, this is clearly due to the differences in climatic conditions and the great territorial variability of precipitation; on the other hand, it also depends on the quantity (and type) of the related available documentary evidence. co nsequently, while even less significant dry spells might have been reported in some years well covered by sources, sometimes even a great drought event may have remained forgotten due to lack of sufficient documentation. based on our present knowledge, this is also true for the carpathian basin where both the great territorial variability of precipitation (also of precipitation extremes) and the uneven spatial and temporal coverage of documentary evidence may prevent the detection of most dry spells and droughts occurred in the middle ages. looking around in the broader neighbourhood, multiannual drought periods were documented in the east european plain both in the early 1360s and the early 1470s (e.g. klimenko and solomina, 2010). droughts, dry spells and low water levels in medieval hungary (and croatia) i … 13 concerning the german areas (esp. the southern and central parts), in parallel to our discussed case studies, glaser (2008) suggests that summer drought occurred in the years 1473 (also in 1471, 1472 ), 1479 (and the year before) as well as in 1506. as for spring droughts both 1479 and 1507 are listed among the drier years; additionally, the autumn was also suggested as dry in 1507. as we can see, our case studies have some parallels in central europe with special emphasis on the areas west, north and northeast to the carpathian basin. unfortunately, at present little is known in the topic concerning the areas south and east to the carpathian basin, except for the early 1362 drought evidence referring to trogir at the dalmatian coast (for locations, hereafter see fig. 1). however, since at that time trogir – with large part of dalmatia – also belonged to the hungarian crown, this case is included in the present paper in more detail, and is discussed in the next chapter. spring 1362 in dalmatia: drought and duke's grazing permission the first drought evidence, discussed in the present paper, is not from hungary or the carpathian basin, but from trogir (trau) at the dalmatian coastline. on 25 march (2 april in gregorian calendar – hereafter gc) in 1362, the duke of dalmatia and croatia (banus) gave permission to a pastoral community called gens morlachi (the so-called 'black vlachs') to stay with their animals within the boundaries of the town of trogir until the day of saint george (24 april; gc: 2 may), because of the great drought (ed.: smičiklas et al., 1915; fejér, 1834). this special (and rather exceptional) permission was issued by the duke (ban) of dalmatia in the name of the hungarian king especially because of the great drought. the permission was given in order to avoid the mass extinction of their animals which formed their predominant property (and incomes); as suggested in the charter, particularly the young lambs were in danger of death ("..., tamen quia emporis nimia siccitas et onerosa nunc ad presens in tantum imminebat, ac etiam agnellorum teneritas a loco ipsius habitationis remoti fuissent in maximum damni periculum incidi potuissent,..."). thus, in the dalmatian zagora area, due to the drought, there was not enough water and grass to feed the animals (even on basic level). this fact indirectly also indicates that the situation at that time was not so severe along the seashore as in the hinterlands, in the surrounding (limestone) mountain area (zagora): morlachs temporarily could stay in a piece of land in the trogir area where fresh water was also available for their animals. the dating of the charter (25 march in julian calendar – hereafter jc) as well as the duke's permission suggest that at least the usual winter–early spring pre fig. 1 locations in late medieval hungary, croatian kingdoms and austria, mentioned in the present study (historical settlement names in brackets) 14 kiss and nikolić (2015) cipitation was missing in (late) 1361–1362. for us the most important information is that, according to the contemporary eye witnesses, at that time great drought prevailed, and it had already lasted long enough to have clear threatening signs that forced morlachs to leave their territory and go into a clear conflict by entering (using, and causing damages in) the lands of trogir. additionally, the wording "in those times" may allow thinking in a broader time frame of months concerning the severe water deficit in the area. as the morlach sheperds were allowed to stay with their animals only up to 24 april (gc: 3 may), this fact may indicate the protection of belongings before the taxation date (day of st. george); but also that they hoped for some april–may precipitation. as we can see, beyond mentioning great drought in early–mid spring time, the case has some further interesting social consequences: the pastoral community had to leave and go beyond its usual grazing territory, and entered the (prohibited) territory of the town of trogir. this caused controversies with the citizens of trogir that a decision and an exceptional solution (and guarantee), with reference to the special environmental conditions, were needed from the highest legal-political authority (duke and the king). thus, not only the terminology but also the following special legal solutions suggest the extraordinary nature of the drought event. a probable further interesting (although some later) contemporary information from hungary is that, according to the protesting charter of the canon and bishop of veszprém against the parish priest of pest (today ebudapest) town, the grape harvest of a particular vineyard in the pest area started in this year rather early, as the tithe was already taken by 22 september (jc; charter edition: fejér, 1834; regesta: bártfai szabó, 1938). for 1362, no drought or dry spell evidence for this year are available in the czech or german databases. however, in austria 1360 was a drought year (rohr, 2007), and information is available on the great drought of 1361 in the polish evidence (malewicz, 1980). additionally, the years of the early 1360s were also an important multiannual drought period (including 1362) in the east european plain (e.g. klimenko and solomina, 2010). from a multiannual perspective it is also interesting to mention that in the years 1363-1366 locust invasion were reported in italy (taken by the ne winds, the "vento schiavo temperato" from the direction of the s-carpathian basin; see: camuffo and enzi, 1991), in 1364 in tyrol/austria and germany (see rohr, 2007; glaser, 2008). furthermore, central governmental acts organising the distribution of crops were initiated in 1362 in bohemia (brázdil and kotyza, 1995) and in 1364 in hungary (for charter edition: fejér, 1834). apart from the 1362 charter, problems with morlachs were further mentioned in other years in the late medieval period, although without referring to any natural hazards as a cause. as discussed by klaić (1880; 2010) the morlachs caused problems with occupying areas for grazing or were mentioned in connection with a settling process in charters dated to 1344 (ed: ljubić, 1870), 14 december 1357 (ed.: smičiklas, 1914), 5 november 1383 (ed.: stipišić and šamšalović, 1916), 2 november 1387 (ed.: gunjača and stipišić, 1981), 17 june in 1402 (ed.: hrabak, 2010) and in 1465 (ed.: kukuljević sakcinski, 1863). although without possessing any direct (or even indirect) evidence we cannot draw any further conclusions, it is interesting to add that in some of these years longer dry spells were mentioned, for example, for the german areas (glaser, 2008) in 1344 (summer), 1383 (summer and autumn), and in 1402 (spring). furthermore, dry periods were reported one year earlier, in 1464 (spring and summer; and also in the preceding years), and in another case one year later: in 1388 (autumn). the great drought of (1473-)1474 and some potential consequences an extraordinary (multi-)annual drought? concerning the year of 1473, extreme dry and hot weather was reported for the czech lands. other sources reporting on the same weather conditions in the entire poland and many parts of the german areas (for overviews, see e.g. malewicz, 1980; brázdil and kotyza, 1995; glaser, 2008). moreover, the contemporary polish history writer, jan długos, himself also mentioned that the unprecedented heat and lack of rain also prevailed in whole europe (dlugos 1877–1878). it is, therefore, somewhat surprising that the similarly contemporary antonio bonfini in his very detailed work about hungarian history did not mention this fact at all, only the drought of the next year. 1473 was the year when king matthias led military campaigns to silesia against the polish king, and the only detail bonfini noted (apart from the very detailed descriptions of military and political/diplomatic operations) that there was food shortage in poland and the polish troops struggled with shortage of food supply, a problem which was clearly not present in the hungarian camp (ed.: kulcsár, 1976). from our point of view, bonfini's descriptions in hungary starts to be interesting from late winter, 1474: on 7 february ottoman troops suddenly crossed the danube and the maros rivers, destroyed many settlements, but especially the rich merchant town, (nagy)várad (today oradea in romania; see also: florianus, 1884). the quick crossing and appearance of a significant (even if not big) turkish army in várad, very far from the turkish-hungarian borderline, may suggest cold and dry conditions (i.e. little or no snow) already in late january–early february in the south-east parts of medieval hungary (see fig. 1). however, descriptions on the real drought came later: for this year, bonfini reported on the great shortage of water ("insolita hoc anno aquarum penuria fuit") and year(s)-long drought – in which springs dried up ("siccitas perennes quoque fontes exhausit") – (ed.: kulcsár, 1976). due to this drought, main rivers of the country had very low water levels, and the ottoman turkish troops could (again) enter hungary by crossing the main rivers ("turci superato savo pannoniam incursarunt."). bonfini's dating is clear and correct: the year of these turkish attacks undoubtedly took place in 1474. nevertheless, while describing the drought, bonfini in his text applies the word "(siccitas) perennes" which has the meaning of the 'entire year', but it may also mean a peri droughts, dry spells and low water levels in medieval hungary (and croatia) i … 15 od longer than a year. the lack of mentioning 1473 drought in bonfini's case can also be explained as the author, whose primary interest was on politics and speak in favour of the hungarian king, simply did not find 'important enough' to mention in more detail the circumstances that weakened the polish army against hungarians in the silesian 'affair', while in 1474 it was rather important to mention the environmental circumstances that clearly helped the ottoman-turkish troops in their rather successful military campaigns. furthermore, it is interesting to add that 1473, as the year of a great heat and drought in hungary, is more widespread in the literary tradition of non-contemporary evidence than the 1474 drought itself: for example, in the domestic early 17th-century chronica leibitzeriana (in the spiš area), similar to the 17th-century chronicle of caspar hain from the same region (bal, 1910–1913), great heat and drought are dated for the year 1473 (schmauk, 1889: "mcdlxxiii. jam magnus calor & siccitas fuit incipiendo a pentecoste (jc: 5 june, gc: 14 june) usque ad festum omnium sanctorum (jc: 1 nov., gc: 10 nov.), ut silvae a sole acccensae sint, & radices etiam in terra exaruerint."). however, there is no mention of the 1474 drought at either places. also referred by antal réthly in his compilation on weather events (1962), the mid-16th century swiss polyhistor, conrad lycosthenes (1557) similarly reports on the great drought that caused forest fires and rivers drying up in hungary, and also that even the danube would have been crossable in 1473, in the year when the king of cyprus, jacob (ii) died ("aestate ob siccitatem & aestum nimium syluae incensae, flumina siccata, ita ut danubius in hungaria meabilis fieret. iacobus cypri rex obiit, ..."). still, there is always a possibility that the two 17th-century chronicles took the year (and the information) from the same local german 16th-century source (in general, see e.g. szabó, 2014), and this is as well probable in case of the mid-16th century german author, lycosthenes. therefore, even if it is possible that already 1473 was dry in hungary, these non-contemporary sources alone cannot be applied to support the idea. a potential consequence? the great locust invasion in (1473–)1474–1479 a probable consequence of the great drought, affecting large parts of europe, was the severe locust invasion started in the same years (in moldova and further) and lasted until the end of the decade. in the austrian continuatio mellicensis (ed.: pertz, 1851), the beginning of a 3-year long locust invasion is dated to 1473: coming from moldavia, locusts spread over in transylvania, hungary, and reached as far as bohemia and linz in austria ("1473. .... eodem anno et sequentibus tribus locustarum grex magnus et innumerabilis ex moldavia emersus, per totam transsilvaniam, ungariam, usque bohemiam, et in austria usque lincz multa debachatus est."). locust invasions are usually associated with dry periods; their long-distance travel is strongly connected to specific changes in wind circulation. locust invasion of hungary was as well mentioned referring to 1474 in the (styrian) chronicon anonymi leobiensis; in this later case the chronicler specifically mentioned them to be seen at esztergom (see fig. 1) located in central hungary (as a later, additional note to the early 14th-century part of the chronicle: "anno 1474 in hungaria apud strigonium idem genus locustarum modo quo hic est expressum apparuit."). both polish and czech chronicles mention 1474 as the starting year of locust invasion (brázdil and kotyza, 1995). in this case dating of czech sources is especially interesting because, as the continuatio mellicensis suggested, the (usual) route of locust invasions led through hungary, then continued to the czech lands, most probably via the vienna area, and further in the danube valley, towards linz. similarly, according to the contemporary domestic chronicon dubniciense (ed.: florianus, 1884), this locust invasion happened in the same year as the turkish attack of (nagy)várad (today oradea, romania), in 1474. moreover, the same source clearly dates the great amount of locusts to july and august which appeared in such quantity that, except for the leaves of vine stocks and trees, they consumed all green vegetation ("nec hoc tacendum esse putaui, quod in estate anni predicti signanter in julio et augusto mensibus, innumerabiles et incredibilis multitudinis locuste, catheruatim quasi magni montes, per climata et partes dicti regni hungarie hinc inde volitantes vise sunt; que omnia virencia pro usu earum preter folia arborum et vinearum vendicarunt,.....". see also: csukovits, 2008). thus, the locust invasion most probably started in the areas east to the carpathian basin in 1473, and the outbreak in hungary occurred in the next year, in 1474. concerning duration of the locust invasion the information is more diverse: the continuatio mellicensis suggested 3 years (presumably for austria), czech narratives referred to 2 years, whereas for hungary the chronicon dubniciense claimed that this locust invasion lasted almost/around 5 years. however, taking 1474 as the starting year of the invasion and 1479 as the last year, this invasion lasted for 6 years in hungary. as we will see, similar to the starting year(s), the last year(s) of this great locust invasion was also famous of its extensive drought. drought, low water levels, turkish attack and locusts: 1479(-1480) as described by the contemporary author, antonio bonfini (ed.: kulcsár, 1976), again for the luck of the ottomans, great drought occurred in early 1479: up to the 7 kalenda of april (jc: 26 march; gc: 4 april) there was no rain at all ("fortuna turci audaciam sequitur fovetque, nam tanta siccitate is annus exaruerat, ut ad vii. kalendas usque aprilis nunquam tantum pluerit, quantum sitibundum terre dorsum parumper aspergere potuisset."). bonfini blamed this winter and early-spring drought for the extraordinary low water levels of the sava and drava rivers. the two rivers had so little water that, rather unusually, in many places they were passable. the drava, that has always been a navigable river, became passable on foot ("utraque pannonia savo hinc et dravo illinc circumventa istro munitur et turcorum 16 kiss and nikolić (2015) incursum amnes inhibent, pre insolenti vero siccitate savus in plerisque locis vado transiri poterat. dravus semper ac ubique navigabilis eo anno pedibus traiici passus est; in causa fuit insolentissima siccitas, cum fluvii tres ubique navigentur."). the possibility of an easy crossing provided (again) a great opportunity for some ottoman turkish troops to attack slavonia, westhungary up to vasvár (castrum ferreum) and styria up to radkersburg in summer, where they caused immense damages ("turcus vadi exploratorem invenit ad dravum, quem multa mercede conduxerat. transmisso iam savo triginta turcorum milia in dravi repente ripa consedere ac ii tutum vadum edocti superato amne pannonias invadunt, in pagos, in homines ac pecora iuxta deseviunt, ferro ignique isquequaque debacchantur, ad castrum usque ferreum et ad styriam rachospurgumque decursant."). according to bonfini, the ottoman attack occurred in august, when the king and his people were occupied by the country meeting in olomouc. it is interesting that, even if the turkish attack occurred in (mid–late) summer, bonfini blamed the winter–spring drought for the low water levels of the sava and drava rivers. nonetheless, due to the very low water levels, the rest of the spring and summer had to be also dry. in the further understanding of extreme low water level conditions we also have to take into consideration that in the german scientific literature both 1478 and 1479 were mentioned for their dry summers: in 1479 also spring was notably dry in the german areas (glaser, 2008). in the czech lands no such problem is mentioned for 1478, but the summer and early autumn of 1479 were hot and dry. heat and drought were even more significant, in 1480 (brázdil and kotyza, 1995). about the turkish attack to carinthia through bosnia in august 1478 (jc: ca. 10 august; gc: 20 august) only the many (3000) casualties due the broken drava bridge (but no drought) were mentioned by the polish chronicle writer (długos, 1877–1878). however, bonfini (as we could see before) explicitly mentioned at the year 1479 that the great drought made crossing and invasion clearly easier for the ottomans. in the same time, according to the chronicon dubniciense, in hungary locusts made the greatest damage in the last years of their stay (since 1474), namely in 1478 and 1479 (ed.: florianus, 1884: "... et iam admodum multiplicate continuis annis in regno durauerunt, fere quinque annis integris, dampna indicibilia, signanter hoc anno, scilicet millesimo quadringentesimo septuagesimo octauo inferentes, et similiter in anno millesimo quadringentesimo septuagesimo nono."). either as a separate case or as a continuation of the 1479 drought, great aridity is also reported by a contemporary source (gyöngyösi's vitae fratrum eremitarum) in spring 1480, when – fulfilling the king's request – the paulines of the budaszentlőrinc monastery carried out a religious procession asking for rain. the rain did arrive during the procession, and refreshed the vegetation (source ed.: hervay, 1988; see also: fedeles, 2007). as a conclusion, similar to the previous 1474 case the very low water levels of major rivers, together with the consequent ottoman turkish attack, were reported to be caused by a prolonged drought. due to the severity of water deficit, this drought lasted most probably longer than a three-month winter-early spring period, suggested by the contemporary chronicler, and the drought might have continued (maybe in a lesser extent) in spring and most of the summer, too. furthermore, based on some german parallels we cannot exclude the possibility that the previous year might have been also drier than usual, and (again similar to the case of 1473-1474) the fact that bonfini did not mention drought for the previous year does not exclude its potential occurrence. although antal réthly, referring to bonfini, also mentions a drought in 1478, in the works of bonfini drought is mentioned only under the year 1479 (and not in 1478). drought, low water level, food shortage, turkish attack in 1494 the large-scale, half-year drought a more direct and detailed report of a clearly severe and extensive drought is available 15 years later: as reported again by antonio bonfini (ed.: kulcsár, 1976) in his extensive works, in the year of 1494 there was continuous drought for six months in hungary ("quin etiam tempus maxime idoneum nacti, quod et rex in transylvanie finibus aberat et perpetua sex mensium siccitas omnes prope amnes, qui ungarie propugnacula sunt, ita exhauserat,..."). rivers, that protected hungary (as well as croatia and austria) against ottoman turkish attacks, had so low water levels again that it was easy to cross them and thus, in the entire october turkish troops continued destroying lands in south hungary and slavonia, and they also attacked and devastated south-styria up to pettau (today ptuj in ne-slovenia) ("... ut multis in locis facile traiici vado possent, per totum octobrem mensem populationes atque indencia usque ad petoviam perduxerunt."). moreover, since these events were followed by a hard winter in which all rivers were firmly covered by ice, the turkish troops could return to the sava river, killing those who were unable to proceed ("inde dravo ad petoviam traiecto et magnis detrimentis illatis hominum ad septem milia abduxerunt. post autem metu, ne intumescentibus sub imminentem hiemem omnibus aquis intercluderentur, ad savum regressi, quicunque aut etatis aut corporis imbecillitate languoreque sequi non potuerunt, eis capita in ripa fluminis detruncarunt ...."). it is an interesting fact that while they easily crossed the sava, they continued mainly to the northwest, and crossed the drava only at pettau (i.e. did not attack the transdanubia to the north by crossing the drava at its lower sections, but rather styria, and crossed the drava at its upper sections, much before its confluence with the mura river). in an important letter sent by queen beatrix (king matthias's widow) in march 1496 (mnl, dl 98454), the queen asked the count of the máramaros (today maramureş, north-romania) chamber about a large transport of salt that has not arrived since 1494 droughts, dry spells and low water levels in medieval hungary (and croatia) i … 17 ("quoniam et computa tue administrationis salim camere nostre maramarosiensis anni 1494. noviter elapsi ex relacione venerabilis philippi de brixia rationalis nostri intelleximus te in dicto tempore fecisse incidere tumenos salium …"). it seems that a rather large amount of salt had not been transported in 1494, and (maybe) remained in the chambers at the tisza, as – due to lack of waters – they could not deliver the salt ("de qua quantitate apparet remansisse in cameris prope ticiam, qui non potuerunt onerari propter defectum aquarum /tumenos?/ 20728,"). thus, the tisza river (where the salt transport was carried out in those times) had so low water levels at least for several months (or the entire year) in 1494 that the transportation of large quantity goods, usually carried in large vessels, was not possible. the letter is silent about the character of the period concerning the next year: we cannot be certain whether the water level of the tisza was still low in 1495 or it was due to other reasons why the chamber administrators did not send the salt afterwards. based on all information, and also king vladislas' transylvanian itinerary (see e.g. neumann, 2014), the halfyear dry period most probably started at least in midor late spring and continued throughout the summer months. apart from the long-lasting drought, we especially have to emphasise the reported great spatial extent of the events: the low water levels of major rivers can be detected in contemporary documentation not only in the south, southwestern parts of the carpathian basin, but dry conditions also prevailed in the (north-)eastern parts, and resulted very low water levels of water flows, including the (upper)tisza river. as mentioned by bonfini, the drought period was followed by hard winter when the danube was firmly frozen which repeatedly helped ottoman turkish military operations in the south. apart from bonfini's general description on the drought that prevailed in hungary, we do not know how much the drought affected the more northern, northwestern areas. nevertheless, (maybe showing some similarities to the 1507 case), as mentioned in the contemporary town accounts of the royal town of sopron, torrential rain or cloudburst caused great damages in the vineyards of sopron in late june (text ed.: házi, 1936). a possible consequence? food shortage in setransylvania regarding the same year, a rather thought-provoking information on food shortage is also available concerning the east-transylvanian secler sepsiszék area (today in central-romania): according to an early september royal charter (ed.: szabó, 1872), the king allowed the sepsi secler delegates to go home earlier from the diet, and also to send much less armed men (only 1/16) to the royal army, due to the great need and shortage of crops and beverages that prevailed in their homeland in that year ("annone et victualium caristia, qua nunc ista vestra patria laborat"). knowing that the 1494 drought primarily affected the upper (mountain) catchment area of the tisza river in (north-)transylvania, it seems probable that the same drought (combined or not with other natural hazards) could be also responsible for the very bad harvests and food shortage of some secler basins, located in the south-eastern part of transylvania). it is rather interesting that up to now, apart from the contemporary reference of marcin biem (limanówka, 2001) concerning south-poland (cracow area), in the scientific literature no analogous events (or even a dry spell or low water levels) are known (see malewicz, 1980; brázdil and kotyza, 1995; rohr, 2007; glaser, 2008) for this year in the neighbouring areas. as for the czech lands and upper-austria, in fact rather the opposite weather conditions are described: an early may flood was followed by a very unfavourable, wet summer and then by bad harvest; similar information is available for the salzburg area where both the summer and autumn were very wet (brázdil and kotyza, 1995). 1507: great drought, hail, bad harvest and poverty a contemporary buda citizen, jános kakas, mentioned in his almanach that almost in the entire year, and especially in the summer of 1507 there was very great drought in hungary (source ed.: kubinyi, 1971), resulting a significant shortage of crops, wine and hay ("1507. hoc fere anno et maxime in estate ingens siccitas viguit per hungariam ubique, ex qua non mediocris penuria frugum, vini et feni provenit."). and this is not the only record about the great drought event: a rather extensive set of evidence about this drought, other natural hazards and their consequences were described in the accounts of the bishop of eger, ippolito d'este (source ed.: e. kovács, 1992). it is an especially interesting fact that the great drought reportedly affected even such high elevation areas as eperjes (today prešov in ne-slovakia; see fig. 1) in former sáros county where leasing and purchase of the tithe was collected after crops: the leasing (arenda) and purchase of the tithe were partly paid (on 15 july jc) and partly postponed (to 6 dec. jc) due to the fact that the great drought in this year destroyed the crops ("quia siccitas magna isto anno destruxit fruges"). this last sentence is very important, because here the tax collector gave the great drought ("siccitas magna") as 'the' reason for the destruction of cereals. additionally, the very great drought ("maxima siccitas") was also mentioned later, in relation with the saint demetrius market in the town of eger (jc: 26 oct.; the day when sheeps were traditionally driven back from the open pasture): at that time the cabbages were bought (to be salted), and as there was very great drought, they were (placed) in the meat market (166v. "…. item in foro sancti demetri (október 26.) caules ad salsandum emit pro castro fl. quadraginta uno et d. octuoginta quattuor et hoc fuit propter maximam siccitatem, ideo fuerunt in caro foro."). a summer information in the account books is that some time after 4 july a horse, bought in transylvania, died in the way between eger and esztergom due to the heat (".... et recesserunt 19 iunii ab agria et quarta iulii expedivi ipsos a strigonio, cui aloisio etiam assignavi unum equum ex equatibus sancti ioannis, loco quorum 18 kiss and nikolić (2015) dimisit unum et veniendo ab agria ad strigonium et erat de illis sex emptis in transilvania mortuus est in via propter calores"). further interesting information is that in this year there were no fishes in the fisheries (belonging to eger), and therefore the poor serfs received reduction of the tax (or leasing) ("agrie 22 septembris. … item ivi extra ad videndum piscaturas, in quibus anno isto non sunt pisces,.. quia pauperes iobagiones non debent agravari in omnibus expensis"). moreover, in many cases all over the areas of the bishopric it is also mentioned that there were no bees ("apes vero non fuerunt"). in the heves district in heves county (and also in borsod) the harvested crops were bad ("male fruges sunt omnes"), and the administrator of the bishopric mentioned that the (bad) price of crops was due to the very bad quality ("quia male fruges et pessime fuerunt"). in the same county, in the debrő (see fig. 1) district the tax officer similarly reported that although there was some harvested grain, it was worthless ("quas fruges dederunt capetie ducente tritulate, quia nulius valoris fuerunt"), and as he also mentioned in detail, market (selling) prices fit the very bad quality of crops ("et videtur, quod sit vendite octingente et quinquaginta tres cum media et dederunt pretium ut supra et capetias novem et plus modicum pro uno fl. et hoc est, quia pessime fuerunt fruge"). similar problems were reported from borsod county kaza district ("quia anno isto hic male fruges fuerunt et vernalia multa intus etc"), and also in miskolc district (in the same county) where the bishops' administrator added that he saw the bad selling prices, and grain (harvest) was generally bad there ("videtur dedisse capetias duodecim pro uno fl. et nota, quod hic generaliter non bene venduntur et fruges etiam male fuerunt"). in zemplén county, in the zemplén district tax was only collected in 1508, and in the homonna district (today homonné in e-slovakia), due to the hail, they could not collect any harvests ("quia anno isto habuerunt grandines in istis duobus districtibus et non potuerunt collocare in acervis"). regarding the tithe of cereals (frugum) of the pásztó district in heves county (see fig. 1) almost similar problems were described: the tax officers noted that the cereals were bad in general (i.e. in growth, in quantity/quality), and were destroyed by rains ("quia fruges male generaliter huc sunt et per pluvias destructe fuerunt"). thus, in these cases not the drought, but hail and rains (convective events?) were blamed for the loss of harvest. in bereg county the tithe incomes of szalánk (shalanky, today in ukraine) and bene (see. fig. 1) were rather small and the wine was "light" ("que vasa sunt valde minora ceteris et vina sunt levia"), and – as later mentioned – the sold wine was rather bad ("quia vina sunt villissima"). similarly a small quantity was reported in the razon (kazon/kaszony? – today koson' in ukraine) district ("exegit vasa media, que sunt valde minora") in the same county. the low quantity of wine both in 1507 and 1508 were noted in the bishop's estate in gyöngyöspüspöki (today part of gyöngyös town). concerning the payment of the wine tithe of pásztó in heves county (collected on 6 dec. jc) the inhabitants asked (and received) a reduction of 10 fl. (they should have paid 75, but paid 65) because the hails destroyed vines and caused lots of other damages ("quia grandines ibi anno isto destruxerunt vineas et passi sunt multa damna /et ut moris est insimilibus/ relaxavi ipsis fl. decem"). similarly, amongst others, the great damages caused by hail was a main reason of tax reduction (on 14 march) in tolcsva (zemplén county; in the tokajhegyalja wine region) from the wine tithes ("….. et nota, quod maxima damna passi sunt per grandines anno isto ...."). as was also indicated in the further parts of the accounts (talking about the travel to eger and return to esztergom), the officer mentioned that "great dearth of things" prevailed ("112v. item predicto eundo, stando et inquirendo equos et veniendo domum cum famulis eorum et stabulariis et cum equis exposuerunt a recessu suo ab agria usque ad adventum ver reversionem eorum fl. quinquaginta novem et certe consideratis omnibus et maxime caristia magna rerum, in via non multum exposuerunt."). possibly the combined effects of natural hazards, followed by bad harvest in basic beverages, resulted the great need. in felnémet (see fig. 1) people received tax reduction in this year due to their great amount of works on the st. john church that had burnt down ("residium relaxatum est, quia multum servierunt ecclesie sancti iohannis isto anno propter combustionem"). described in other parts of the text in more detail, the church of st. john (in eger) was struck by lightning and burnt down in 1506. in tárkány and cegléd people did not have to pay the tax of st. michael (jc: 29 sep.) because of their poverty ("propter paupertatem"). this question once more appears later when, apart from poverty, their serving works were also mentioned ("servitia et paupertatem"). great poverty (e.g. in tárkány: „43v. census sancti michaelis (jc: 29 sep.). …. tharkan debuisset dare fl. quattuor, sed propter nimiam pauperitatem sunt eis relaxati.”) continued also in the next year and provided reasons for further tax reductions in 1508, too. the account also mentions that disease prevailed (p. 319: " pestilentia") in the same year. in these cases the reason for tax reduction was mainly the great poverty of people. an interesting further information was reported in the same account books (4 october, 1507): the wines collected in besenyő and keresztúr (today szirmabesenyő and sajókeresztúr, located near the sajó river; see fig. 1), were partly destroyed, and the remaining part had to be moved to the castle, due to the fact that cellars were filled with water. these circumstances suggest either a (late september–early october) flood (maybe flash flood, torrential rain?) or maybe very high ground water conditions in the area. as for conclusion, on the one hand a buda citizen emphasised the great drought that prevailed in hungary in general, and caused a bad harvest of crops, vine and hay in 1507. on the other hand, from the accounts of the eger bishopric a broader picture can be obtained: apart from generally low incomes in this year, the great and very great drought was emphasised to be primarily responsible for bad harvests in two cases. rather interestingly, drought severely droughts, dry spells and low water levels in medieval hungary (and croatia) i … 19 affected the higher elevation areas in the north-northeast (prešov area, e-slovakia). further cases suggest that, apart from the great drought, hail and rainfall caused great damages in the crop harvest as well as in the vine stocks in a number of cases in central and north-east hungary. moreover, in summer the drought was combined with heat (at least) in the central parts of the carpathian basin. as a result, an extraordinary bad harvest of crops, hay and sometimes also wine was generally reported not only in the central, northeastern, low elevation areas of the country, but also in the hilly areas. the low amount and bad quality of crops and wine may suggest that, beyond the significant impact of other natural hazards, (similar to the german areas) already the spring was characterised by a serious water deficit that probably continued (combined with heat and maybe convective precipitation events) in summer and (at least partly) in autumn. among other, further consequences a casualty (caused by heat), combustion and, apart from bad harvests of cultivated vegetation, in some areas the lack of fish and in many cases that of bees were reported. as a further cumulative effect (of combined hazards – on an annual or multi-annual level), shortage/lack of beverages and especially poverty prevailed (as well as disease mentioned) in extensive areas, and formed the basis/reasons of tax reduction. there might have been a change in weather around the end of september and/or beginning of october towards a more rainy character that induced flood (and/or high ground water table). referred in the réthly compilation (1962), in his work the contemporary author, antal verancsics (1504-1573; source ed.: bessenyei, 1981) gives the information on the extremely great prices due to the shortage of bread, under the year 1508 ("mondhatatlan nagy drágaság támada egísz magyarországban, kinérnek szík vóta miatt."). very great need in 1508 was also mentioned in the account books of the eger bishopric, while referring to the expenses of a travel from eger ("et certe consideratis omnibus et maxima caristia magna rerum, in via non multum exposuerunt"). later in this year a lack of bee-products namely honey and wax (in late march in eger: "quia anno non fuit mel neque cera") was described, and also poverty and pestilence were recorded in the accounts. apart from this indirect evidence and the potential consequences of the extreme danube flood in summer 1508 mentioned in austria (see e.g. rohr, 2007) that most probably also affected the danube valley in hungary, we have at present no more information concerning the character of 1508, and therefore we cannot say in what extent the hazards of the previous year(s) and/or those of 1508 are responsible for the critical conditions prevailed also in 1508 in large parts of hungary. as suggested before, in the czech lands the summer months of 1506, with special emphasis on june, were mentioned as significantly dry (brázdil et al., 2013), while in the german areas (according to glaser, 2008) not only summer 1506, but also spring and autumn of 1507 were notably dry. as for other areas in europe, apart from the dry spell in spain (e.g. dominguez-castro et al., 2008), in 1506 a significant drought preceded the lisbon massacre in portugal (see e.g. de gois, 1749). a thought-provoking further information from outside of europe is that 1506 was the last year of a severe multi-annual drought, for example, in central mexico (therrell et al., 2004). at present, our only available weather-related information concerning the year of 1506 in hungary is the above-mentioned lightning and fire of the st. john church in eger, and a flood – most probably influenced by ice – at the end of the year at buda that suggest a rather cold (late autumn-)early winter in this year (recorded by the afore-mentioned buda citizen, jános kakas; see in: kubinyi, 1971). discussion drought severity towards a numerical classification the magnitude of drought events is usually discussed with using numerical values. in historical climate/hydrology research usually a 3-scaled index classification is applied. this classification is in fact the 'dry part' of the 7-scaled precipitation (monthly) index classification, commonly applied in historical climatology (brázdil et al., 2013; see also glaser, 2008; pfister, 1999 etc.). while in more modern times usually an adequate amount of source evidence is available to classify the intensity of a drought event, the situation is often rather different in the middle ages when only one or two short contemporary notes are available on the individual events, and the severity of individual months often cannot be defined. in our present cases terminology (siccitas; ingens/magna siccitas; maxima siccitas), information on the approximate length of the drought as well as severity of consequences (extraordinary low water levels of major rivers for a longer duration, bad harvest due to drought etc.) provide further help in estimating the severity of the individual drought events. due to mentioning durations, the picture is relatively clear in case of the 1474, 1479, 1494 and 1507 events: the drought of 1474 is described as annual (or even longer) in duration, the 1507 drought was mentioned as a 'whole year, but especially summer' event, while in case of 1479 a 3-4-month (at least), and for 1494 a 6-month drought was mentioned by the (same) contemporary author. concerning 1474, 1479 and 1494 extreme low water levels of major rivers and the related historical events (i.e. intensified turkish attacks – utilising extraordinary low water levels) directly and indirectly also supported the description. as for territorial extension, in 1474, 1479, 1494 and 1507 the authors mentioned "hungary" and thus, probably in these four cases large parts of the carpathian basin had to be affected by long dry periods. additional information on low water levels of the drava, sava and the tisza rivers, and the largescale socio-economic consequences also suggest that extensive areas (including the alpine catchments) had to be affected by the long-term water deficit. less is known about the 1362 dalmatian case: although great drought (and need for water) is mentioned, some important socio-economic consequences are known that suggest a significant long-term winter-early spring water deficit, no explicit information in the contemporary documentation is available about the length of 20 kiss and nikolić (2015) the drought event. this later information, however, would be probably the most clear indicator of a severe drought (see e.g. pfister et al., 1999). nevertheless, the rather exceptional nature of socio-economic consequences and legal/administrative decision (as well as some potential central european parallels) may suggest that this drought event was also extraordinary in magnitude. social, political, economic, military and environmental consequences when talking about the socio-economic effects of droughts, we may group the consequences as follows: 1) military operations and devastation of extensive areas (including mass loss of lives) supported by hydrological drought (1474, 1479, 1494): the southern defence line of the hungarian kingdom (and also of slavonia) against the ottoman empire – due to the unfavourable, flat lowland conditions of the borderline areas – was largely dependent on the hydrological defence line formed by major rivers, such as the drava, sava and the danube and their extensive wetland areas. apart from the winter cases when firm ice cover of major rivers and the lack of notable snow provided good conditions for a rapid 'raid' of ottoman turkish troops (e.g. winter of 1474), prolonged low water levels of major rivers (and dry roads) in the summer half year provided equally favourable conditions for intensive military attacks. these military attacks in the last decades of the 15th century affected not only the countries of the hungarian crown, namely hungary, slavonia (and bosnia), but also the south-eastern parts of austria (especially styria). thus, repeated (and prolonged) great drought events provided more possibilities for military attacks, reported during the dry 1470s and in 1494. 2) transportation problems during hydrological drought, due to extraordinary low water levels (1494): while low water levels ease the possibilities for crossing, it may cause great problems in river transportation when lacking the sufficient depth of water has the result that deficiencies occur in the supply of even basic beverages such as salt. thus, although other environmental circumstances, such as great flood (or damages caused by great flood) or shortage of labour could obstruct salt transport along major rivers (e.g. along the maros river in 1496; see hna, dl 65441), in the middle ages (even if at the moment in only one known case), drought (long-lasting low water levels) could be also a reason for major transportation problems. 3) drought caused problems for pastoral communities, and – due to lack of sufficient quantity of fodder and drinking water – threatened with a mass instinct of domestic animals: in the drought case of 1362 domestic animals were mentioned to be threatened by prolonged drought. in this case the usual grazing practices and territory of the pastoral community had to be changed temporarily: morlachs had to leave their territories and (shortly) occupy those of a highly privileged town, to avoid significant loss of animals. 4) agricultural, socio-economic drought: can be mentioned in relation with the (very) bad harvests, high prices, food shortage and poverty in 1507 (with food shortage and poverty also in 1508). although drought is a prevailing factor and may be the main reason for significant socio-economic problems, the drought was combined with other (related) hazards such as heat and convective events (hail, destructive rainfall). bad harvests, high prices and related uncertainties (even probable casualties) might have been a result of these combined effects (affecting extensive areas). 1507 is the only case when more information is available for a combination of hazards and their consequences. need and high prices in this year (1507) may be the result of the current bad harvest; however, also with using other central european parallels, it is that the rather wide-spread poverty was due to the fact that (apart from other social, political circumstances such as generally growing uncertainties due to turkish attacks in other parts of the country, high taxes etc.) unfavourable conditions prevailed not only in 1507, but also in 1506 (as, for example, in the german and czech areas), and 1507 would have been already the second year (at least?) with bad harvest results. 5) a further interesting, potential (biological) consequence, also resulting great loss in the cultivated vegetation, might be that around the same time when drought prevailed locusts also arrived (even if the exact consequences on social processes are not reported) and were present (most probably in the 1360s and) in the 1470s. while this invasion caused clearly further socio-economic problems, locusts were 'only' directly reported in hungary during the drought events of the 1470s (and in the countries where usually locusts arrive from hungary or slavonia in the 1360s), while no information is available for their mass appearance in the drought years of 1494 or 1506. however, the outbreak of locust invasions in the 1360s and 1470s clearly coincides with, for example, the prolonged multiannual drought periods occurred in the east european plain in the early 1360s and 1470s. one-year shift (or not) with central-european droughts – any comparison possible? although relatively few information is available concerning great medieval droughts, it is interesting that most of the great drought mentions are available concerning the last decades of the 15th century and for 1507. however, due to the low sample size, at present it is yet difficult to draw any conclusion whether or not, compared to other periods, the number of great drought events increased around the turn of the 15th-16th century. the present 'distribution' of known drought evidence is strongly dependent on source availability: as we could see before, most direct mentions of great droughts come from narrative sources, charters and from economicadministrative (institutional) evidence. prior to the mid15th century, narratives and accounts (if available) very exceptionally contained weather-related information, and in the charter (and letter) documentation, significant in quantity especially from the early 14th century, any drought-related information appears only in very exceptional cases. even if source availability strongly affects our knowledge about medieval droughts, it is still an interesting question why in hungary (or in dalmatia) the known great drought years detected are often one year droughts, dry spells and low water levels in medieval hungary (and croatia) i … 21 late in the studied cases compared to the reports of other central european areas. first of all, we have only a few cases and on this basis no general tendencies can be drawn. it is, however, true that in most of the studied cases, namely in 1362, 1474, 1479 and 1507 important drought events were reported in neighbouring areas for 1361, 1473, 1478 (and/or 1480) and 1506. it is most probably not the 'fault' of the sources: the referred sources are all domestic, contemporary, clearly dated and although the work of bonfini has vital importance in 1474, 1479 and 1494, the early 1362 drought was described in a legal document (charter), while the 1494 and 1507 drought cases were mentioned in two-two individual contemporary sources (and also in different source types). we rather suggest that – similar to some of the czech, polish and german examples – in some years water deficit might have occurred not only in one, but two (or more) consecutive years, and the drought itself got recorded only concerning the year when the major effects and consequences (i.e. socio-economic) became apparent. this is also possible because, as we could already see in the individual case studies, based on the textual context as well as the severity of consequences, it is possible that dry conditions might have already prevailed in the preceding year(s). conclusions and outlook although relatively few contemporary sources are yet known that directly refer to droughts occurred in medieval hungary and croatia, some of the important events are quite well-discussed in the contemporary written sources. out of these cases, in the present paper the great droughts reported for 1362 in dalmatia, and for 1474, 1479, 1494 and 1507 in hungary and partly croatia (but also affecting the eastern alpine area) are discussed in more detail. it is also an advantage of the available contemporary evidence that the discussed drought events were recorded in various source types, including narratives, economic accounts, private notes, charters and letters – all written by contemporary authors. it is a common characteristics of these drought cases that they were all rather extraordinary in magnitude, but still were mainly mentioned due to their socioeconomic (and political-military) consequences. the long-lasting severe shortage or lack of precipitation resulted extreme low water levels of major rivers accompanied by transportation and border security problems on the one hand, and – combined with other natural hazards – harvest failures, severe food shortage and danger of mass extinction of domestic animals on the other hand. two (or maybe three) of the mentioned great drought cases were accompanied or /followed by significant locust invasions. comparing the discussed drought cases with the drought-related evidence available for central europe (czech lands, poland, austria – and also the german areas), in four cases (i.e. 1362, 1474, 1479, 1507) parallels can be found for the preceding year, than for the year actually mentioned in the hungarian-croatian evidence. due to the fact that droughts are usually known when consequences were reported, in most cases it is probable that not only the actually mentioned year, but already the previous year was dry. in the present paper the reported, most extraordinary medieval drought events were discussed in more detail. however, either in the form of direct or indirect reference, more evidence is available on other dry spells, shorter or longer dry periods that will be discussed in a further publication on the subject. acknowledgements the work of the first author was finalised in the framework of the 'flood change' erc research grant. the authors are grateful to györgy szabados (hungarian medieval studies research group in szeged, national academy of sciences) and danuta limanówka (center for poland's climate monitoring, warsaw) for their help. references bal, j., förster, j., kauffman, a. 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europe). historia 29 (5–6), 53–55. wetter, o., pfister, c., werner, j.p., zorita, e., wagner, s., seneviratne, s.i., herget, j., grünewald, u., luterbacher, j., alcoforado, m.-j., barriendos, m., bieber, u., brázdil, r., burmeister, k.h., camenisch, c., contino, a., dobrovolný, p., glaser, r., himmelsbach, i., kiss, a., kotyza, o., labbé, t., limanówka, d., litzenburger, l., nordl, ø., pribyl, k., retsö, d., riemann, d., rohr, c., siegfried, w., söderberg, j., spring, j.-l. 2014. the year of unprecedented heat and drought of 1540 a worst case. climatic change 125, 349–363. doi: 10.1007/s10584014-1184-2 journal of environmental geography journal of environmental geography 8 (1–2), 1–10. doi: 10.1515/jengeo-2015-0001 issn: 2060-467x downstream morphologic characteristics of the alluvial section of lower river ogun, nigeria olutoyin a. fashae, adetoye faniran department of geography, university of ibadan, 200284 ibadan, nigeria *corresponding author, e-mail: toyinafashae@yahoo.com research article, received 23 july 2014, accepted 9 february 2015 abstract rivers constitute an important focus of attention in surface water studies because of their dynamic nature. therefore, natural rivers develop a wide range of channel forms whose characteristics vary as a function of the position within the fluvial systems. this study examined the river channel morphologic parameters along the alluvial section of river ogun in south western nigeria. data on the channel morphologic variables were collected through field measurement of the bankfull cross sectional characteristics of the river from where the longitudinal characteristics were defined. 48 cross sections were randomly established at bankfull stage along the river channel stretch of 90 km. bankfull depth and width at each of the cross sections were determined using sonar (electronic sounding machine) that was mounted to a boat. velocity was measured with the aid of a current meter, while other morphological parameters were estimated from the field data. analysis of variance revealed that downstream morphological characteristics of the river varies distinctively at each cross section with bedslope as the most significantly varied among all other morphologic parameters (f=91.18; p=0.00). pearson product moment correlation technique revealed that bankfull width had a correlation of 0.8 and 0.9 with wetted perimeter and cross sectional area respectively while bankfull depth (maximum) had correlations of 0.9, 0.8 and 0.78 with hydraulic radius, wetted perimeter and cross sectional area respectively. the research also revealed that gradient affects the discharge with a positive correlation of 0.9. the study ascertains the extent of variability in the morphologic characteristic of river ogun which provides scientific basis for river maintenance and management. keywords: bankfull depth, bankfull width, alluvial section morphologic characteristics, river channel, lower river ogun introduction the assessment of river condition relative to some ideal state is a concept receiving increasing attention in fluvial geomorphology. the morphology of any river shows a great variability and dynamic behaviour. therefore, the river channel as a subsystem and an important component of the river basin system deserves studying in some details to enhance river-basin management which provides scientific grounding for river maintenance and management. monitoring of channel morphology extends understanding of types and rates of responses to environmental changes. a proper understanding of this is essential for mined-land reclamation, channel modification for flood control and navigation, identification of areas of active tectonics and the litigation of boundaries etc. (elliot, 1984). river channel morphology provide information on river characteristics and behaviour, infact, river morphology has been a subject of great challenge to scientists and engineers who recognized that any effort with regard to river engineering must be based on a proper understanding of the morphological features involved and the responses to the imposed changes (chang, 2008). examining river network behaviour enhances understanding of the way in which geomorphic processes behave across networks. several river condition assessment methods have been designed for countries worldwide; ausrivas (parsons et al., 2002), the index of stream condition (ladson and white, 1999; ladson et al., 1999), the river habitat audit (anderson, 1993) and river styles (brierley and fryirs, 2005). river styles for instance, provides a framework for assessing river condition using geomorphic criteria and achieves this largely by comparing the geomorphic character of reference reaches to test reaches of similar river types (brierley and fryirs, 2005). the investigation of river channel morphology and the attendant features is an interesting aspect of geomorphology which is of immense importance in understanding the processes affecting landforms. therefore, geomorphic river condition assessments are valuable mechanisms for determining the present and future health of river systems (maddock, 1999). river morphology depicts the form of a river along its length and across its width and consequently its shape. river morphology is explained by channel patterns and channel forms, and is influenced by such factors as discharge, water surface slope, water velocity, depth and width of the channel, amount and size of the transported material, river bed materials, etc. these factors are not independent but inter-related to each other. several studies had been carried out on the form and 2 fashae and faniran (2015) shape of river channels for instance, soar et al., (2001 suggests that stream system adjusts in order to maintain a steady state, or dynamic equilibrium between the driving mechanisms of flow and sediment flow and the resisting forces of bed and bank stability and resistance to flow. ward and d’ambrosio (2008) in their study on stream classification identified factors that can influence channel morphology and concluded that channels with bedrock, have limited sediment supply whereas cobble and gravel bed channels are high energy channel with high sediment supply. therefore, erosion instability, mass wasting and debris flow are more dominant processes as the bed material become finer and these affect channel morphology. they also emphasize slope as a major factor in channel morphology, as slope changes from upstream to downstream, an in relation the channel morphology also changes. moreover, montgomery and buffington, (1997) emphasized that spatial variation is sediment supply may govern channel morphology in different segment of rivers. channel response to increase sediment supply depends on the ratio of transport capacity to sediment supply. they linked the variables of channel morphology such as width, depth, bed slope grain size, bed forms and patterns to function of sediment supply, transport capacity and vegetation. transport capacity in terms of frequency, magnitude, and duration of discharge and slope. riparian vegetation also influences channel morphology in different ways. vegetation protects banks from erosion and increases flow resistance by increasing roughness and reducing flow velocities so that channels with dense riparian forests tend to be narrower (brookes et al., 2000). moreover, vegetation on river banks and woody debris within the channel may act as sediment traps that create different channel morphologies and modify the channel type (schumm, 2005). all these factors affect river channel morphology. over the last several decades, stream morphology researches has been undertaken by scientists in a wide variety of disciplines, yet our understanding of channel morphology, features and the factors influencing them is still incomplete. most geomorphological investigations involving channel morphometry are concerned with the definition, measurement and analysis of quantitative indices describing the cross section, the bedform and long profile as well as the plan geometry of rivers (goudie et al., 1990). according to goudie (1990), morphology and particularly the cross section and plan-form properties of the channel has increasingly been linked to river flow characteristics which are also related to properties, quantities of bed materials and transported sediments. every river channel has its own characteristics that is unique in its own way and the dynamism involved in downstream river morphologic variables suggests the need for quantitative understanding of the behavior of river morphologic variables and this remains an important but yet elusive goal in fluvial geomorphology. alluvial rivers are dynamic landforms subject to rapid change in channel shape and flow pattern. examining alluvial river network behaviour enhances understanding of the way in which geomorphic processes behave across the channel. the variation in river channel morphology is a result of great range of hydrological conditions, sediment characteristics and geologic histories of the river. the nature of the materials through which a river flows initiates the three types of stream channels: bedrock, semi controlled and alluvial. alluvial channel is composed of sediments transported by the river and it is susceptible to major morphologic change and to significant shifts in channel position as the alluvium is eroded, transported and deposited, and as the sediment load and water discharge changes. since the alluvial section of any river is dynamic in nature in terms of its morphology, there is the need for a quantitative understanding of alluvial cha nnel form and response to changes in governing conditions remains an important yet elusive goal in fluvial geomorphology (fashae, 2011). analysis of river channel morphology appears to have been largely studied as many of the research efforts on river channels have focused almost exclusively on channel pattern (ebisimiju, 1994; holz and baker, 1981; beschta and platts, 1986; thorne, 1997; friedman et al., 1996). since, river channels show some common characteristics in areas of similar landform. the river channel as a subsystem and an important component of the river basin system deserves studying in some details to enhance river-basin management. this is the reason for examining some aspects of river channel morphology along the alluvial segment of river ogun before empting into the atlantic ocean at the lagos lagoon by analyzing the channel morphologic characteristics, interrelationship among the morphologic variables and the downstream variation for channel morphologic variables. study area the ogun river basin is located between latitudes 6 o 33’n and 8 o 58’n and longitudes 2 o 40’e and 4 o 10’e (fig. 1). the catchment area is about 23,000km 2 . river ogun takes its source from the iganran hills at an elevation of about 530m above mean sea level and flows southwards over a distance about 480km, before it discharges into the lagos lagoon. the lower river ogun is defined for this study as the stretch from mokoloki town to isheri town downstream, especially areas underlain by sedimentary abeokuta formation which consists mostly of sandstone of medium to coarse grain, poorly sorted and micaceous (oyawoye, 1972). there are clay and mudstone intercalations; cross bedding is common and the rock is soft and friable, except where cemented locally by ferruginous materials. the main sedimentary rocks are the alluvial deposits, coastal plain sands both of quaternary age. the choice of this portion of the ogun river as the study site for this research work is based on the fact that most of the principal factors that control river geomorphology, namely: climate, geology, hydrogeology and relief, are relatively constant along the study segment of river ogun coupled with the fact that the river is perennial in its flow. downstream morphologic characteristics of the alluvial section of lower river ogun … 3 the climate of the study area is controlled by the inter tropical discontinuity (itd). the itd is an atmospheric zone between the maritime south west monsoon wind and the dry north east trade winds. this zone in west africa moves with the location of the sun in such a way that during the southern summer, the itd moves close to the coast and during the northern summer, the itd moves northwards to about latitude 1415 o n. as a result, the rainy and dry seasons are well marked. the rainy season begins earlier in the south where it lasts from march until the end of october or early november, giving at least seven months of rainfall. north of oyo and iseyin, the onset of the rains is delayed and generally begins late in april or early may and ends in mid-october (ogun river basin development authority, 1981). in late july and early august, dry days are prevalent and sufficiently regular to constitute what has been termed the “little dry season”, with mean monthly figures below 100mm. the mean wet seasonal rainfall is about 1,015mm to 1,525mm in the lower ogun river and about 510mm to 1,525mm in the upper (ogun river basin development authority, 1981). the actual number of rainy days ranges from 250-280 days. the mean annual rainfall of the study area ranges from 900mm to about 2000 mm (ogun river basin development authority, 1981). temperatures are fairly uniform throughout the year with a mean annual of 26 o c -27 o c with an annual range of 5 o c to 8 o c while the relative humidity ranges between 60% and 80% (ogun river basin development authority, 1981). annual evaporation rates are also high throughout the year, with monthly amounts varying from about 90mm in july to over fig. 1 map of river ogun showing the alluvial river study segment 4 fashae and faniran (2015) 130mm in january. the mean annual water surplus of the study area ranges from 254mm in the north to 508mm in the coastal belt. the total annual potential evapotranspiration is estimated at between 1600mm and 1900mm. the lower river ogun is characterized by low slope angle and extensive floodplains with marshes and swamps. the total catchment of the lower ogun is approximately 12,630km 2 while the length of the study stretch is approximately 90 km. the lower ogun basin, where the study stretch lies has a mean slope of about than 3% and the landform consists of plains with straight and gently undulating topography. the general topography is characterized by a low, flat plain along the river, subject to frequent seasonal flooding and influenced by groundwater. for instance, at mokoloki, the river bed sediments are coarser, making this section of the river channel relatively shallower and narrower, water being contained in less than 20% of the channel width while at the much lower section around isheri, the channel is characterized with an average bankfull width of about 115.6m. much as result of the downstream increase in the discharge and it subsequent production of alluvium that are mined for construction purposes. river ogun basin comprises of two major rivers; oyan and ofiki at the upstream section, while other tributaries such as the rivers ewekoro and adiyan are located at the lower extent of this study section (fig. 1). some of these tributaries are areic with no definite course. there is a lot of human influence on the river for instance, a number of portable water projects were mounted on the river for the provision of water to the rural populace. these include the mini water works at akute (fig. 2). the drainage pattern of the river is dendritic in nature. many of the subsequent and obsequent rivers and stream often dry up completely during the dry seasons while the consequent river (ogun) often have reduced water level and discharge thereby leaving extensive floodplains and migratory bars at the sides. the lower river ogun is characterized by a minimum discharge value of about 2.3m 3 /s and a maximum values of 40 m 3 /s at akute . an increase in downstream discharge is indicative of the sudden change in the channel gradient due to the impoundment of water by barrage at akute (fig. 2). in addition, within downstream locations, further adjustments of the channel efficiency were achieved by the changing channel pattern of meanders and braids. this is evidenced with the occurrences of some fluvial forms such as ripples and pools sequences and formation of sand bars by the alluvium material and methods the morphological variables were evaluated for both the longitudinal and cross sectional profiles of the river to provide useful information on the state of the river channel at the time the study was carried out. the morphologic variables were collected through field survey where a total of forty-eight bankfull cross sections was unevenly surveyed at bankfull stage along the river channel stretch of 90 km. this is as a result of the occurrence of straight, meandering and braided channels along the river channel. the bankfull width and depth were also measured using automated sde-28 echo depth sounder (sonar) whose visual interface was mounted in fig. 2 barrage at akute along river ogun with the insert showing the width downstream morphologic characteristics of the alluvial section of lower river ogun … 5 the boat and the traducers was attached to the base of a moving boat, then suspended into the water to receive sound signal that translates into the depth values. the sonar machine has the capability of measuring the width perpendicular to the direction of the sounding from bank to bank. the depth values were collected at the centerline of the river. bedload material was collected using the grab sampler technique by scooping the river bed to trap materials for its particle size at equidistant locations along the cross section. these materials were mixed together to obtain a composite representation of the cross section before taken to the laboratory for analysis using the hydrometer method. the coordinates of each cross section were recorded with the aid of an attached garmin global positing system (gps). beschta (1986) suggested that any attempt at characterizing channel morphology must recognize its three-dimensional aspects, therefore all the other channel morphologic variables, such as wetted perimeter, hydraulic radius and cross sectional area were calculated. current meter was used to obtain measurements of the flow velocity from which the discharge of the river at each cross sectional point was estimated. analysis of variance (anova) that states that there is no significant variation in the downstream morphologic variables at 0.05 significant (α-) level was used to test for the variation of the downstream morphologic variables. results the longitudinal profile of lower river ogun the alluvial section of the lower river ogun channel at bankfull stage suggests a concave-upward shape along its downstream gradient (fig. 3), with an elevation of 29.7m above the mean sea level at mokoloki located at a distance of about 10km downstream the studied segment of river ogun while the elevation at isheri is 8.1m above the mean sea level which is about 90 km downstream of mokoloki, thus the river drops 21.6m along the studied reach. hence, longitudinal zonation of channel forms may be recognized from the headwaters downstream to the river mouth. it could be observed that there is a progressively lower gradient and an increase in the bankfull discharge as reflected the continuous addition of tributa ries and increasing drainage area downstream. the profile is punctuated at knick points where the river cuts through valley floors as indicated at about 58km distance which is sharply defined due to human inte rference of the location of a barrage and sand mining activity respectively. the linear relationships that typically exists between gradient and downstream distance along the longitudinal profile of river og un reveals r 2 = 0.49, a value significant at 0.05 α-level with gradient accounting for 49% in the variation. the significance of the gradual lowering in the channel gradient provides explanation for the erosive and deposition work along the meanders and braided sections of the river and the plausible reason for the i ncrease in fluvial landforms along the study stretch. features such as ripples and pools sequence are evidenced at the concave and convex sections of these meanders which are interspersed by braids between the 10km to 40km downstream distance. these fe atures are created by pattern scour and deposition at bankfull discharge where the riffles tend to occur at the inflection points and pools at bends. also, oxbow lake, a lake with curved plan occupying cut-off channel reach that has been abandoned were encountered along the stretch while point bar deposits which are sediments laid down on the inside of meander bend largely by accretion are more pronounced. fig. 3 longitudinal profile of lower river ogun 6 fashae and faniran (2015) number of factors are responsible for the concavity of river longitudinal profiles, notably the energy profiles best represented by the discharge pattern. this is evident from the linear relationships that typically exists between gradient and discharge along the longitudinal profile of rivers, which in this study reveals r 2 = 0.98, a value significant at 0.05 αlevel (fig. 4). variation of river ogun channel morphologic variables with downstream distance river channel morphology of an alluvial channel reflects the movement of water and the particle size of the load flowing in it. the volume of water flowing within the channel together with the sediment load (dissolved and bedload) helps in shapening the channel morphology. a statistical description of each mo rphological variable along the channel is important as it provides a general summary illustration of the tendencies peculiar to the study (table 1). depth and width are important variables of a river channel that suggests the morphology of any river. the maximum bankfull depth, which is indic ative of the thalweg, or a line drawn to join the lowest points along the entire length of a riverbed shows that 4.3 m was the minimum point while the max imum was 9.6 m. the range of 5.3 m in the maximum bankfull depth indicated a wide gap between the deepest and the shallowest points along the thalweg from the centre line of the channel. however, the mean bankfull depths varied from a maximum of 7.4m to a minimum of 3.7 m. figure 3 revealed that as the river tends towards reaching its mouth and with increasing distance downstream, there is an fig. 4 relationship between bankfull discharge and gradient along the lower ogun river channel table 1 morphological characteristics of the lower river ogun with the downstream analysis of variance (n =48) downstream variables range (min-max) mean (standard deviation) downstream f-ratio variation (significance value) downstream distance from mokoloki (km) 80.8 (10.1-90.9) 25.1(16.8) maximum depth (m) 5.3 (4.3-9.6) 7.7(1.2) 0.42 0.66 mean depth (m) 3.7 (3.7-7.4) 6.0(0.8) 1.19 0.30 bankfull width (m) 84.4(31.1-115.6) 59.8(15.3) 0.40 0.68 width-depth ratio (-) 14.2(5.1-19.4) 10.2(3.2) 1.21 0.31 crossectional area (m 2 ) 800.6(253.8-1054.4) 458.0(142.0) 0.08 0.93 wetted perimeter (m) 86.3(47.6-133.9) 75.1(15.2) 0.30 0.74 hydraulic radius 4.0(3.9-7.9) 6.0(0.8) 0.24 0.79 discharge (m 3 /s) 29.0(10.9-39.9) 2.3(9.1) 0.67 0.8 particle size ratio 54.0(39.2-93.2) 71.3(14.4) 0.34 0.72 bedslope (frictional slope) 0.4(-0.1-0.3) -0.005(0.09) 91.18 0.0 valley gradient 21.6(8.1-29.7) 17.0(6.7) 0.69 0.51 velocity (m/s 1 ) 1.0(0.2-1.2) 0.5(0.2) 0.68 0.80 downstream morphologic characteristics of the alluvial section of lower river ogun … 7 increase in depth which might be as result of the corresponding increase in downstream discharge except for the knick points that experience a huge increase in depth (fig. 5). the knick points along the studied river section are indicative of accumulation of bedload at the barrage at akute with an increase in gradient. even though depth increases downstream, distance alone might not account for variation pattern observed (fig. 6). fig.5 relationship between discharge and downstream distance fig. 6 relationship between downstream distance and depth the increase in depth suggests that there is a downstream increase in suspended sediment concentration which would invariably dampen turbulence (merritt and wohl, 2003). it was observed that there is a relationship between the particle size of the bed materials (mean=71.3) and the channel form with a decrease in size downstream. this accounts for wide, shallow and fine/smoother banks. theoretically, the bankfull width of a river is a function of its occurrence, magnitude of flow, type of transported sediment and composition of the bed and bank materials of the channel. the lo wer river ogun channel is characterized by a minimum bankfull width of 31.1 m, maximum bankfull width of 115.6 m and a mean of 59.76 m along the study stretch. although river channel widths may genera lly increase downstream, a channel can still have a stable width even though the river is migrating la terally at a constant annual rate. as clifton (1989) suggested, overall width, depth, and cross section area do not increase systematically downstream, while the spatial variability results from prevailing vegetation conditions. the width of a river can therefore remain relatively constant where erosion on one bank is compensated for by corresponding sediment deposition along the opposite bank. this is evident in some sections of the river where there are widths changes due to their response to the fluctuation in the rainfall amount and intensity that encou rages the formation of migratory sand bars along this alluvial river (fig. 7) however, the downstream increase in width may be attributed to the composition of the bed and bank materials of the river channel. t his could be linked to removal of the riparian vegetation for active farming activities (fashae, 2011). in summary, the morphologic characteristics of the river channel vary at different points along the river segment. this variation is indicated in the di fferences in values of the variables observed from the cross sections of the river. in order to provide an understanding of the variability of the channel mo rphologic factors in the study area, investigati on of the spatial variations of the channel form variables along the downstream was carried out. the results revealed that variations occurred in virtually all the parameters downstream as reported in table 2 where the analysis of variance for all the channel form variables indicated that there are variations. the f ratio which implies the extent of variation showed that the bed slope (f ratio 91.18 was the most variable downstream among the morphologic parameters considered followed by width depth ratio (1.21), while the cross-sectional area is the least variable with an f ratio of 0.08. the bed slope with f ratio as high as 91.18 is the most widely varied downstream, less variations occur in particle size ratio downstream with f ratio of 0.34. however, o nly the variation in bed slope reflected a statistical significant difference at 0.05 α-level while all other parameters varying downstream albeit with no statistical vari ations. this can be attributed to the fact that the study was carried out within a definable reach that is, along the alluvial segment (5 th order) of river ogun. the significant variation in bed slope was however attributed to the rapid changes in the work of the river downstream, since the discharge increases systematically downstream, it is not unreasonable to expect the down cutting of the river channel bed changing as the flow, erosion and deposition actions changes, even within the same reach of the river. furthermore, the finding that the bed slope and width depth ratio were the most variable morphological parameters along the 5 th order section of the river 0 50 100 150 200 250 300 350 0 20 40 60 80 100 d is c h a rg e ( m 3 /s ) downstream distance (km) 0 2 4 6 8 10 12 0 10 20 30 40 50 60 70 80 90 100 d e p th ( m ) downstream distance (km) 8 fashae and faniran (2015) ogun channel was instructive because the two are about the best variables conceptually considered to describe the changes in channel shape. the increment in width depth ratio as the river flows towards its mouth is represented in fig. 8. fig. 8 relationship between width depth ratio and downstream distance interrelationship among river ogun channel morphologic variables the interrelationship among channel morphologic variables along the alluvial section of the river ogun was investigated using correlation analysis, to test the relationship occurring among the channel form variables. this technique deals with associations between two or more variables providing measures of the strength of association and statistical tests of its significance. the pearson's product moment correlation method which considers parametric relationships was employed because the morphologic variables were measured at random intervals. this relationship was particularly considered with reference to the distance downstream, the result of which is reported in table 2. the width depth ratio at any point along the river ogun channel was expectedly most influenced by the bankfull width with a correlation of 0.9 significant at 0.05 α-level while the wetted perimeter had a correlation of 0.8. the cross sectional area had a correlation of 0.9; the hydraulic radius dependent on the bankfull depth (maximum and mean) and the cross sectional area had correlations of 0.9 and 0.8 and 0.78 respectively. in addition, as the river channel tends to near its mouth, the discharge, gradient and the flow velocity all reduces in magnitude. the width depth ratio, the bankfull width, wetted perimeter and the hydraulic radius also changes significantly as revealed from the multivariate graph in figure 9. as the width depth ratio and the bankfull width increases towards the mouth of the river, the hydraulic radius decreases. these were detected along the section investigated in this study to reveal negative correlation of -0.36 and 0.34 between downstream distance and bankfull width as well as width depth ratio respectively, significant at 0.05 α-level occurs, while a similarly positive correlation of 0.23 occurs between downstream distance and the hydraulic radius. this implies that the portion of the river distinctively describes the width, depth and hydraulic characteristics of river ogun channel. downstream of river ogun suggests that there is a reduction in the channel boundary resistance due to alluvium along the banks, while the channel-bed materials become slightly fine grained. the channel bed is composed of fine sand particles and the banks are mainly non-cohesive (miller, 1956). the substantial changes observed in the correlation matrix has been reported in other studies including pattern c hanges 0 4 8 12 16 20 24 0 10 20 30 40 50 60 70 80 90 100 w id th -d e p th r a ti o ( -) downstream distance (km) fig. 7 migratory sand bars along the lower river ogun channel riparian vegetation alluvium sand bar downstream morphologic characteristics of the alluvial section of lower river ogun … 9 (graf, 1988a), substantial widening (burkham, 1972; osterkamp and costa, 1987; kresan, 1988) and lateral migration (graf, 1983b), entrenchment (graf, 1983a) and floodplain erosion and deposition (wells, 1990; zawada and smith, 1991). discussion and conclusion rivers from source to mouth show a great variation in morphological characteristics such that the size and shape of the channel readily describes the section of the river. from the study, it can be inferred that among the eight morphological variables studied. the bankfull width and the depth of the channel indicate the most significant attribute of the channel form. the width depth ratio and bed slope were found to be the most variable morphological parameters along the studied channel. this is instructive because the two are the best variables conceptually considered to describe the changes in channel shape. the ratio of stream channel length to down-valley distance, which was measured on the long profile of the river ogun, indicated the stream type (alluvial) and how the stream channel slope was adjusted to that of the valley slope. the interrelationship among channel morphologic variables along the alluvial section of river ogun revealed that both the width depth ratio and the cross-sectional area at any point in the channel table 2 correlation matrix of downstream channel morphologic parameters distance downstream maximum bankfull depth mean bankfull depth bankfull width width depth ratio cross sectional area wetted perimeter hydraulic radius distance downstream 1 maximum bankfull depth 0.41 1 mean bankfull depth 0.08 0.82 1 bankfull width -0.36* -0.12 0.00 1 width depth ratio -0.34* -0.56 -0.55 0.90* 1 cross sectional area -0.10 0.46 0.48 0.82* 0.39 1 wetted perimeter -0.30 0.04 0.13 0.80* 0.73* 0.90* 1 hydraulic radius 0.23 0.90* 0.80* 0.30 -0.22 0.78* 0.45 1 *correlation significant at 0.05 α-level fig. 9 downstream pattern of the morphologic variables along the lower river ogun 0.1 2 40 10 100 v a lu e s (l o g ) distance (log) wetted perimeter hydraulic radius discharge particle (sand) ratio gradient velocity 10 fashae and faniran (2015) were most influenced by the bankfull width with a correlation 0.82 significant at 0.05 α-level. also, the wetted perimeter was equally related to the bankfull width with a correlation of 0.8 and the cross sectional area with a correlation of 0.8, the hydraulic radius was found to be dependent on the bankfull depth (maximum and mean) and the cross sectional area from a correlation of (0.9 and 0.8) and 0.78 respectively. the gradient of the channel most perfectly affects the discharge with a positive correlation of 0.9 significant at 0.05 α-level. the downstream increase in channel width might be due to the loose bank materials which reflect on the bank cohesion and roughness of the channel. the river discharge which is closely related to the flow velocity and the channel cross sectional area summarizes the processes occurring within the alluvial section of the river ogun channel and resultant fluvial features, such as braids, incised meanders, point bars, riffles and pools. references anderson, j.r. 1993. state of the rivers project. report 2. implementation manual. qld brisbane. andrews, e.d. 1984. bed-material entrainment and hydraulic geometry of gravel-bed rivers in colorado. geological society of america bulletin 95, 371–378. doi: 10.1130/00167606(1984)95<371:beahgo>2.0.co;2 beschta, r. l., platts, w. s. 1986. morphologic features of small streams: significance and function. water resources bulletin 22, 369–379. 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recorded in flood sediments of northern coastal peru. geology 18, 1134–1137. doi: 10.1130/00917613(1990)018<1134:hhoten>2.3.co;2 zawada, p.k. smith, a.m. 1991. the 1988 orange river flood, aplington region. terra nova 3, 317– 324. northwestern cape province, rsa. journal of environmental geography journal of environmental geography 10 (1–2), 31–39. doi: 10.1515/jengeo-2017-0004 issn: 2060-467x spatiotemporal assessment of vegetation indices and land cover for erbil city and its surrounding using modis imageries shwan o. hussein1*, ferenc kovács1, zalán tobak1 1department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: shwan.huseen1@su.edu.krd research article, received 28 march 2017, accepted 2 may 2017 abstract the rate of global urbanization is exponentially increasing and reducing areas of natural vegetation. remote sensing can determine spatiotemporal changes in vegetation and urban land cover. the aim of this work is to assess spatiotemporal variations of two vegetation indices (vi), the normalized difference vegetation index (ndvi) and enhanced vegetation index (evi), in addition land cover in and around erbil city area between the years 2000 and 2015. modis satellite imagery and gis techniques were used to determine the impact of urbanization on the surrounding quasi-natural vegetation cover. annual mean vegetation indices were used to determine the presence of a spatiotemporal trend, including a visual interpretation of time-series modis vi imagery. dynamics of vegetation gain or loss were also evaluated through the study of land cover type changes, to determine the impact of increasing urbanization on the surrounding areas of the city. monthly rainfall, humidity and temperature changes over the 15-year-period were also considered to enhance the understanding of vegetation change dynamics. there was no evidence of correlation between any climate variable compared to the vegetation indices. based on ndvi and evi modis imagery the spatial distribution of urban areas in erbil and the bare around it has expanded. consequently, the vegetation area has been cleared and replaced over the past 15 years by urban growth. keywords: modis, remote sensing, vegetation index, ndiv, evi, land cover, time series introduction the rate of urbanization is increasing throughout the world. according to recent united nations estimations, the majority of the world’s population is living in urban areas and the overall proportion is expected to reach 65% in the middle of the 21th century (united nations, 2014). however according to the word bank (2015) the urban population in iraq was already 69.5% in 2015. a gradual increase in the percentage of build-up land results in a reduction of the vegetated areas. urbanization alters environmental conditions such as climate, biodiversity, quality of water and air that has a substantial impact on human comfort and health. the impacts may become pronounced when they interact on a global scale. therefore a better understanding of the effect of urbanization is required to support greener sustainable development and climate change strategies (imhoff et al., 2010). possible solutions include the creation of green spaces, that are irrigated and fertilized, which are found to considerably reduce the negative consequences associated with transformation into urban environment (gregg et al., 2003). remote sensing of urban expansion and vegetation clearing provides information on the spatial and temporal patterns of urban development and its impacts to the environment. modis sensor is able to provide information necessary for monitoring ecosystem dynamics at adequate spatiotemporal resolution using vegetation indices such as evi and the ndvi. vis are spectral transformations of two or more bands designed to enhance the properties of vegetation to allow reliable spatial and temporal intercomparisons to photosynthetic health and canopy structural changes. ndvi is chlorophyll sensitive, while evi is more responsive to canopy structural variations including leaf area index (lai), canopy type and architecture. the vis complements each other and improves upon the detection of vegetation changes and the extraction of canopy biophysical parameters (huete et al., 2002). ndvi was found to be highly sensitive to the vegetation presence as well as its density and dynamics (zhang et al. 2006). for this reason, the modis ndvi can be employed in the quantification of green biomass and vegetation cover. a recent study in china by li et al. (2010) found that modis ndvi was highly correlation with the field verification data of vegetation cover and had obvious advantages for predicting natural vegetation coverage than evi within their study area. modis vis are sensitive to multi-temporal vegetative biophysical and canopy changes. both ndvi and evi have a good dynamic range and sensitivity for monitoring and assessing spatial and temporal variations in vegetation amount and condition. ndvi generally has a higher range of values over semiarid sites, and the opposite for more humid forested sites with a lower range (huete et al., 2002). with the support of satellite imagery time-series data it became possible for researchers to obtain phenological information at various spatial and temporal intervals. looking at publications in the 32 hussein et al. (2017) area, it should be stated that the first use of satellite data in the identification of key phenological parameters using ndvi was described in publications by tucker and myneni (tucker et al., 2001; myneni et al., 2007). however, there is a range of recent studies in developed and developing countries, focused on the application of moderate resolution imaging spectroradiometer (modis) to model trends in vegetation patterns. mertes et al. (2015) demonstrated a methodology over east asia to monitor urban land expansion at continental to global scales using modis data, including a multi-temporal composite change detection approach based on modis 250 m annual maximum evi. the study explained that evi data improved the classification results and is capable of distinguishing between landscape changes in urban environment. a publication by yuan and bauer (2007) demonstrated a strong correlation between percent impervious surface and land surface, covering twin cities of minnesota. lunetta et al. (2006) preferred modis normalized difference variation index (ndvi) for a time series for southern virginia with the available modis quality indicators. colditz et al. (2006) demonstrated the effects of different quality levels of modis ndvi of evergreen broadleaved forest and savanna in western africa. it was found that low quality analysis or very lenient settings resulted in a significant decrease in ndvi during the wet season. therefore, not accurately representing the phenology of evergreen broadleaved forest. a recent study in southern brazil using modis leaf area index has highlighted the merit of the modis quality indicators such as ndvi and evi (rizzi et al., 2006). the main driving factors of vegetation growth are precipitation and temperature (bonan, 2002). water availability, often directly related to precipitation and its variability, is the driving factor for most semi-arid regions. several studies have been conducted on the response time between precipitation and phenological activity using satellite-based vegetation indices (nicholson et al., 1990; los et al., 2006; camberlin et al., 2007). vegetation growth patterns and their connection with climate are studied by vegetation phenology (schwarts, 2013). land surface phenology (lsp) is focused on seasonal features of spatiotemporal variation and lsp is also one of the main ecosystem change indicators (suepa et al., 2016). with the aid of remote sensing imagery information, it has become possible to establish spatiotemporal phenological changes, which enabled phenological monitoring at global, regional and local scales (zhang et al., 2005). the goal of this work is to assess spatiotemporal variations of vegetation indices (evi and ndvi) in erbil and its environment between 2000 and 2015, using modis satellite data and gis methods, to determine the impact of urbanization on the spatial distribution and temporal dynamic of urban and surrounding natural and agricultural vegetation cover. this is conducted by evaluating biannual mean vegetation indices captured in march and december to determine spatiotemporal processes. climate data including rainfall, humidity and temperature is also considered between 2000 and 2015, to enhance the understanding of vegetation change dynamics. correlation analysis is conducted between each climate variable compared to both vegetation indices. dynamics of vegetation gain or loss will be evaluated through the study of land cover type changes. study area the study area for this research is the city of erbil and its surroundings, which is the capital of iraqi kurdistan region (fig. 1). situated in the north-east part of iraq and lies between longitudes 43° 51' 20", 44° 12' 28" and latitudes 36° 05' 58", 36° 15' 54" covering an area around 580 km2. the total numbers of iraq kurdistan residents is approx. 4.8 million people., the area is presented by fertile plains, uphill and mountainous lands (united nations development program, 2016). the zagros mountains (3600 m above the sea level) form the main landscape of the north part of the kurdistan area. looking at the distribution of vegetation it should be indicated that agricultural areas form approximately 34% of iraqi kurdistan while the dominating land cover of this region is fig. 1 overview of erbil study area spatiotemporal assessment of vegetation indices and land cover for erbil city… 33 presented by grasses and forests. the area is mainly characterised as an anticline/syncline system. the tigris river is located in the southern part of the erbil governance. the iraqi kurdistan area is heavily employed for agricultural purposes in iraq (hameed, 2013) (fig. 1). in erbil governance approximately 41% and 59% are formed by arable and non-arable lands respectively (soitm, 2013). the dominating proportion of non-irrigated agricultural crops (93%) is highly dependent on rainfall while the remaining 7% of crops are irrigated. dominate soil types found in erbil as well as the adjacent territories are clay and limestone. their proportions are found to increase with depth. both the upper and the bottom layers of the erbil region soil are composed of brown clay. in addition to the indicated types of formations, soils of the city are presented by sand, plaster and gravel (hameed, 2013). erbil city is located in a transition area characterised by mediterranean and arid climatic features. the climate is characterized by mild winters and warm/hot summers. an average rainfall range in erbil area is 300-400 mm per annum with the highest rainfall levels during the period between october and april. the annual relative humidity in the erbil area is approximately 35% and the monthly average air temperature ranges from 10 oc to 25 oc. the climate of the study area is typically dry in summer with little to no precipitation, while winters are wet (hameed, 2013). in 2011, the erbil municipality has a population of 884,299 people and a density of 6000 persons per km2 and the population is rapidly expanding. data and methodology data modis vegetation indices vegetation indices such as ndvi and evi are designed to provide consistent spatial and temporal comparisons of vegetation conditions and cover, allowing biomass productivity monitoring and quantifying changes in vegetation cover (colditz et al., 2006; mertes et al., 2015; rizzi et al., 2006). the study uses a 16 day composite for each ndvi and evi raster (mod13q1), captured by the modis-terra sensor. blue, red, and nir reflectance bands, centered at 469 nm, 645 nm and 858 nm respectively, are used to determine the modis vegetation indices, with a spatial resolution of 250m (usgs, 2016). modis products are computed from atmospherically corrected bi-directional surface reflectance that have been masked for water, clouds, heavy aerosols, and cloud shadows (usgs, 2016). the equations for ndvi and evi are described below (huete, et al., 2002). the ndvi is determined as: 𝑁𝐷𝑉𝐼 = 𝑁𝐼𝑅 − 𝑅𝑒𝑑 𝑁𝐼𝑅 + 𝑅𝑒𝑑 the evi is determined as: 𝐸𝑉𝐼 = 2.5 𝑁𝐼𝑅 − 𝑅𝑒𝑑 𝑁𝐼𝑅 + (6 ∗ 𝑅𝐸𝐷) − (7.5 ∗ 𝐵𝐿𝑈𝐸) + 1 the purpose of evi is to improve on a standard ndvi modis product. the benefits of evi include; enhancement of vegetation signal and sensitivity in biomass abundant regions, reduction of soil and atmospheric effects and the reduction of the smoke impact, generated as the result of biomass combustion in tropical area (xiao et al., 2009). improving on ndvi, modis includes (evi) that minimizes canopy background variations and maintains sensitivity over dense vegetation conditions (usgs, 2016). the evi also uses the blue band to remove residual atmosphere contamination caused by smoke and sub-pixel thin clouds. the modis ndvi and evi products are computed from atmospherically corrected bi-directional surface reflectance that have been masked for water, clouds, heavy aerosols, and cloud shadows (usgs, 2016). modis (mod13q1) data was employed to create a time series of ndvi and evi over the study area annually, between 2000 and 2015 to determine variations of vegetation extent. modis land cover the study uses modis land cover type yearly l3 global 500m resolution (mcd12q1), land cover type 1 (igbp) global vegetation classification scheme where selected among five global land cover classification systems. the modis land cover product (mcd12q1) is classified into five land cover classes; open shrub land, grassland, cropland, urban/built-up area and bare or spare vegetation. modis land cover is used to carry out change assessment and distribute ndvi and evi to in land cover classes. climate data average temperature, humidity and total rainfall and for march and december were collected from erbil station and plotted over the 15 year period (2000-2015). humidity data was collected at the altitude of 470 m. all climate data was sourced from the kurdistan region government, ministry of agriculture and water resources (2016). methodology the year of 2005 was chosen as a moderate year in terms of temperature and rainfall, to avoid the impact of climate extremes on the results. where average of rainfall and temperatures were extracted for 75 years and the selected year was closer to moderation. both ndvi and evi was march the month of highest value, while the lowest levels of vegetation were identified in december (fig. 2). the project methodology was summarized in figure 3. data compilation and raster statistics were generated in arcgis 10.3. statistical analysis and investigation of possible trends were carried in microsoft excel. pre-processing of satellite data was required and was conducted in the study. data pre-processing for included checking pixel reliability and vegetation index quality. bad pixels are omitted from the analysis as they represent clouds, shadows from the clouds and cover the true value of the ground reflectance. where 34 hussein et al. (2017) the pixel representation must be more than 2/3 of the area, therefore the 2009 data for both march and december contain a very high portion of bad pixels. several years of data captured in december (2000 -2002, 2006-2009 and 2011) also contain very high portions of bad pixels (table 1). fig. 2 mean ndvi, evi time series from months of the year 2005, showing minimum and maximum values in the study area fig. 3 methodology summary of the project mean ndvi and evi were generated to provide an average index over the complete study area, allowing the comparison between years to examine a temporal trend. plots of monthly ndvi and evi statistics (mean, minimum, maximum and standard deviation) are generated from 2000 to 2015, identifying temporal variations. modis land covers (mcd12q1) the quality control of the pixels was verified and all were excellent. conducting detection of change assessment, by comparing the areas of five land covers and generate time series of ndvi and evi within land cover classes from 2000 to 2015. table 1 summary of qa layers good pixel representation for each year march december year pixel representation (%) year pixel representation (%) 2000 100 2000 40.7 2001 100 2001 66.55 2002 100 2002 49.93 2003 100 2003 81.03 2004 100 2004 97.43 2005 100 2005 96.68 2006 100 2006 71.32 2007 100 2007 47.9 2008 100 2008 65.66 2009 56.81 2009 56.83 2010 98 2010 99.47 2011 100 2011 68.02 2012 91.33 2012 87.61 2013 100 2013 90.8 2014 99.88 2014 99.98 2015 100 2015 96.78 mean 96.63 mean 76.04 results this section presents time series scatter plots of mean ndvi and evi values and summary statistics including standard deviation, minimum and maximum. modis ndvi and evi an obvious difference is apparent between march and december of mean ndvi and evi over the 15 year period in the same area, presented in figures 4 and 5. march had significantly higher means and greater variability of vi levels compared to december. december showed some variability at maximum vi levels however the mean was fairly constant with a small peak in 2014. the differences between march and december could be based on seasonal growth variations. after the wet season, march generally has much greater ndvi and evi values, expect for 2008. in december 2008 ndvi and evi values were very similar to the averages in march. both vi in march 2010 showed highest level due heavy rains this month. however both months for ndvi and evi showed a gradual increasing trend from 2000 to 2015 (fig. 4 and 5). important to note is that both ndvi and evi time series plots appear to have similar patterns. ndvi and evi images for march 2002 (baseline) and march 2015 (final year) are compared in figure 6 to visualize the spatiotemporal variation of vegetation. march had the highest vegetation growth, and will best represent differences in true vegetation coverage extent. it is evident that the spatial distribution of urban areas and/or bare or sparely vegetated areas surrounding erbil has expanded over the past 15 years and consequently vegetation surrounding the urban centre has been replaced by urban growth. however it appears that agricultural areas in rural region have expanded possibly to support population growth. the ndvi maps appear to have greater areas of high vegetation health compared to the evi maps (fig. 6). spatiotemporal assessment of vegetation indices and land cover for erbil city… 35 fig. 4 ndvi time series from 2000 – 2015 in the whole area, comparing mean, minimum, maximum and standard deviation values for march and december in the study area fig. 5 evi time series from 2000 – 2015 in the whole area, comparing mean, minimum and maximum and standard deviation for march and december in the study area fig. 6 ndvi and evi maps for march 2002 and 2015 36 hussein et al. (2017) interesting to note, there is a decline in urban green spaces such from 2002 to 2015 in both ndvi and evi images. the green space may still be present, but in poor health or have reduced in size. the ndvi and evi values captured in march had a greater variability, compared to data captured in december. annual modis data captured in march was used to calculate land cover statistics for time series for both indices (fig. 7 and 8). the majority of the years contained vi values with little variation, except for both vi in 2002 2010 and 2014 (fig. 7 and 8). this may be explained by abrupt climatic changes resulting in vegetation growth or decline. the cropland class had the highest ndvi values over any other class during the 15 year period (fig. 7), which is expected as healthy green homogeneity crops will exhibit a higher ndvi value compared to open shrub and grassland ecosystems that contain various plant species with varying foliage colours and types. bare/sparsely vegetated and urban areas displayed the lowest mean ndvi vales over the study area over the 15 year period. fig. 7 mean ndvi values from march 2000–2015, comparing 5 land cover types fig. 8 mean evi values from march 2000 – 2015, comparing 5 land cover types the evi time series presents as well similar trend, as cropland appear to generally have a greater biomass over grasslands and open shrub land over the 15 year period, (fig. 7). cropland evi exceeds grassland possibly from additional crop irrigation for those years. as expected evi in urban areas remains relatively low over the study period, however evi in bare/sparsely vegetated classes seems to spike in 2002 and 2010 (fig. 8). the spikes may be explained by an increase in sparse vegetation species and opportunistic species such as weeds. based on figures 7 and 8 it can be suggested that ndvi is more sensitive than evi for fluctuations in vegetation health and biomass. modis land cover figure 9 compares modis land cover classification between 2000 and 2015. the foremost visual difference is the reduction of bare or sparsely vegetated land and increase in grasslands. the spatial distribution of the urban area has remained relatively similar at this resolution. therefore, we verified through landsat images 30m resolution, where urban and built-up area 58% increased over fig. 9 comparison of modis land cover between 2000 and 2015 spatiotemporal assessment of vegetation indices and land cover for erbil city… 37 the time period (hussein, 2017). the area of land cover types and percentage differences comparing the baseline year 2000, to the final year 2015, are highlighted in table 2. between the 15 years there has been a significant decrease of bare or sparsely vegetated land (90%) and a slight decrease of cropland (18%) and open shrub land (4%). however there has been a 67% increase of grasslands. based on these observations, we can assume the majority of bare or sparsely vegetated land has transitioned into grassland, outside of the urban center between 2000 and 2015. table 2 land cover area and percentage differences comparing 2000 to 2015 2000 2015 land cover area (ha) area (ha) difference (ha) change within cover type (%) open shrublands 42825 41050 1775 -4 grasslands 4375 13150 -8775 +67 croplands 8275 6775 1500 -18 urban and built-up area 7425 7425 0 no change barren or sparsely vegetated 6100 600 5500 -90 total 69000 69000 climate annual rainfall, average temperature (fig. 10), and average humidity (fig. 11) and covering the 16-year period are presented below. rainfall was considerably high in 2003 and 2006, followed by low rainfall years in 2004, 2010, and 2007 (fig. 10). after 2007 total rainfall has remained more constant with less variation between years, with a positive increasing trend towards 2015. fig. 10 total annual rainfall and average temperature time series from 2000 – 2015 fig. 11 annual mean humidity time series from 2000 – 2015 humidity shares a similar pattern to rainfall, with high averages in 2003 and 2006, followed by lows and then a gradual increasing trend towards 2015 (fig. 11). interesting to note, average temperature for 2003 was the lowest over the 16 year period, while in 2006 the temperature was relatively high for that period (fig. 10). in 2010 average temperature spiked at 23oc, the highest average temperature over the 16 years. by comparison total rainfall was very low in 2010 with average humidity. average rainfall, humidity and temperature all appear to have generally increased between 2000 and 2015 with various positive and navigate fluctuations in-between. fig. 12 time series (2000 – 2015) correlation analysis between rainfall, humidity, temperature and vegetation indices (ndvi and evi) within grasslands for march 38 hussein et al. (2017) climate variables were compared with ndvi and evi by correlation analysis (fig. 12-13). rainfall, humidity and temperature averages for march were compared to mean ndvi and evi levels within grasslands and croplands captured in march. there was no strong evidence of correlation between ndvi or evi and any of the climate variables. all comparisons between climate and ndvi or evi were not significant. discussion remote sensing of urban sprawl and green space provides information on the spatial and temporal patterns of human growth that are useful for understanding differences in socioeconomic and political factors as well as environmental and climatic impacts (mertes et al., 2015). based on ndvi and evi modis data (fig. 6) imagery the spatial distribution of urban areas in erbil and the bare around it has expanded. consequently the vegetation area has been cleared and replaced over the past 15 years by urban growth. however it appears that agricultural or grassland areas in rural regions have expanded slightly, to possibly support population growth. based on our observations, we can assume most of bare or sparsely vegetated land has transitioned into grassland, outside of the urban centre. urbanization can substantially alter the abundance and distribution of vegetation (gregg et al., 2003). however this statement is unclear for the city and surrounds of erbil based on the spatial resolution (250m, 500m) of the modis data. a finer imagery resolution of 30m or less is required. mapping within an urban landscape is not an easy task, due to the small footprints of features such as parks and trees, mixed between clusters of buildings and roads. urban areas are typically heterogeneous in both material composition and configuration and with new development they are often highly variable between locations (mertes et al., 2015). vegetation indices are useful for extracting green space features from complex urban areas. the ndvi and evi modis imagery with its course resolution was still able to successfully identify spatial and temporal patterns of human growth in the city of erbil. additional research is recommended utilizing imagery of higher resolution such as landsat with a 30m spectral resolution. to determine the distribution of green space within the urban area of erbil, worldview 2 imagery is recommended with 2m spatial resolution. the urban expansion pattern observed in erbil is highly dependent on the tigris river. the city is represented by a matrix of interconnected patches that vary from non vegetated areas such as impervious surfaces to areas of high plant diversity (soitm, 2013). the combination of vegetated land patches lead to the formation of elevated plant diversity in erbil (neil and wu, 2006). agricultural activities such as clearing, burning and herbicides uses have impacted plant community distribution outside of the urban centers. however within the urban landscape the observed vegetation patterns or urban green spaces (ugs) are a direct consequence of reconstruction activities, including alteration of urban landscape as well as city gardens and forests. the green areas in erbil are managed by governments, institutions and individuals. it is expected that the outlined bodies directly control abundance and biodiversity of green spaces within the city. erbil is one of the oldest cities in the world, therefore it could be expected that the cities preservation activities should be aimed towards green space and plant diversity conversation, however this is not the case (unesco, 2016). urban green spaces are essential constituents of the urban structure that enhance resident’s quality of life and behaviour (m’ikiugu et al., 2012). ugss contribute to the sustainable development of urban ecosystems and provide a range of ecological and social benefits including; biodiversity and historic landscape feature conservation, regulate local microclimate, protection of air quality, noise absorption and water resources protection. ugs also maintain and improve human well-being by contributing to recreation and aesthetic activities (m’ikiugu et al, 2012). fig. 13 time series (2000 – 2015) correlation analysis between rainfall, humidity, temperature and vegetation indices (ndvi and evi) within croplands for march spatiotemporal assessment of vegetation indices and land cover for erbil city… 39 conclusion spatiotemporal variations of vegetation indices (evi and ndvi) between 2000 and 2015 was successfully observed using modis data. it was evident that the spatial distribution of bare or sparely vegetated areas surrounding erbil has expanded over the past 15 years, and consequently vegetation surrounding the urban centre has been replaced by urban growth including grassland or green space. it is suggested the majority of bare or sparsely vegetated land has transitioned into grassland, outside of the urban center between 2000 and 2015. there was no evidence of correlation between any of the climate variables to ndvi or evi. march 2010 was a dry, warm period, which spiked vi averages above normal, mainly because of sparsely vegetated or open shrub lands. opportunistic weed and dry grass species that thrive in these conditions may explain the spike in vi. overall vegetation indices showed a gradual increasing trend from 2000 to 2015, but vegetation extent decreased based on the land cover information. human alteration of the environment has caused a spatiotemporal transition from native plant species to managed monocultures for agricultural purposes or urban development. considering vegetation distribution in the surroundings of erbil city it can be stated that according to the collected modis data the iraqi kurdistan region manifested high levels of vegetation regardless of the period of the year. it is expected that vegetation patterns in this region are highly manipulated and dependent on anthropogenic activity because this region plays an important role in the 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modelling in megech reservoir catchment, ethiopia journal of environmental geography 12 (3–4), 21–31. doi: 10.2478/jengeo-2019-0009 issn 2060-467x calibration, validation and performance evaluation of swat model for sediment yield modelling in megech reservoir catchment, ethiopia abebe tarko assfaw* civil engineering department, college of engineering, debre berhan university, po box 445 debre berhan, ethiopia *corresponding author, e-mail: abe4tar@gmail.com research article, received 2 september 2019, accepted 18 november 2019 abstract intensive agricultural practice in ethiopian highlands results in increasing rates of soil erosion and reservoir sedimentation. the estimation of sediment yield and prediction of the spatial distribution of soil erosion on the upper megech reservoir catchment enables the local governments and policymakers to maximize the design span life of the megech reservoir through implementing appropriate soil conservation practices. for this study, the sediment yield was estimated and analyzed through hydrological modeling (swat). the simulated outputs of the model show that the mean annual surface runoff was 282 mm and the mean annual streamflow was 153 m3/s. similarly, 12.33 t/ha mean annual total sediment load gets into the megech reservoir. the model performance standard used to evaluate the model result indicates that the model was superior in performing the trend of runoff and sediment yield in both calibration and validation periods. finally, the most erosion vulnerable sub-basins that could have a significant impact on the sediment yield of the reservoir were identified. based on this, sub-basin 7, 25, 27, 18 and 29 were found to be the most erosion sensitive areas that could have a significant contribution to the increment of sediment yield in the megech reservoir. considering the land use, soil type, slope, and relief of erosion vulnerable sub-basins cut off drains, fallow land, contour ploughing, fanya juu terraces, soil bunds combined with trenches and trees could be the possible management strategies to reduce the sediment yield in the catchment. keywords: calibration, validation, megech reservoir, sediment yield, swat introduction sediment yield fluctuates greatly because of natural or man-induced factors. climate, soil, topography, land use/land cover and management practices are the most common factors that affect the soil erosion process and sediment yield from the catchment. these factors have a dynamic role in the erosional behavior of soil (wainwright and brazier, 2011). there are mainly three types of soil erosions namely sheet erosion, rill erosion, and gully erosion. sheet erosion is the first phase of the erosion process that is characterized by the uniform removal of soil from the surface. as the severity of the erosion increases rill erosion begins to develop and finally deep gully erosion is formed. it is reported that more than 2/3rd of farmland degradation in africa is caused by soil erosion (tully et al., 2015). soil erosion is a natural and dynamic process that occurs when the force of wind, raindrops or runoff on the soil surface exceeds the cohesive agent that binds the soil together (ifabiyi, 2004). soil erosion caused by water is a serious problem in many parts of the world which causes most of the degradation of agricultural lands. however, the extent and magnitude varies from one part of the country to another depending on the farming practices, population pressure, type and susceptibility of the soils to erosion, local climate, the general terrain formation, and variations in agroecological setting of the area (tebebu et al., 2010; monsieurs et al., 2015). all this implies that locationspecific soil erosion studies are still substantial in ethiopia for arresting the problem of soil loss. the availability of large amounts of water resources and adequacy of topography enables ethiopia to be the most beneficiary of water resource development projects such as dams and reservoirs (setegn et al., 2007). on the contrary poor land use practice and improper management make the reservoirs be in a serious problem of sedimentation even beyond their dead storage capacity. in ethiopia poor land-use practices, improper management systems and lack of appropriate soil conservation measures have been major causes of soil erosion and land degradation problems (tamene et al., 2006). a quantitative expression of soil erosion is a fundamental phase for any watershed management (prasannakumar et al., 2012; khadse et al., 2015). even though different researches (such as haregeweyn et al., 2017; gashaw et al., 2018; miheretu and yimer, 2018; woldemariam et al., 2018; zerihun et al., 2018) have been done so far to estimate soil erosion in the ethiopia highlands, the problem has been increasing (efd, 2010) and it could be worse in the future (niang et al., 2014). intensive agricultural practice in the upper blue nile basin causes land use to be changed rapidly which results in increased rates of soil erosion and sedimentation. this was manifested by the significant downstream impacts and the storage capacity reduction of reservoirs. specifically, the silting of reservoirs is the most challenging problem in the upper blue nile basin. the benefits gained by the 22 assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. construction of micro-dams in the upper blue nile basins were threatened by the rapid loss of storage volume due to excessive sedimentation (tamene, 2006). in megech reservoir catchment the existing land and water resources system of the area is adversely affected by the rapid growth of population, deforestation, surface erosion and sediment transport. many farmers in the area cultivate mountainous and steeper slope land without protective measures against soil erosion and degradation, causing topsoil to be washed out during the heavy rain season. the construction of a dam and the creation of an impounded river reach area usually change the stream natural conditions. the dam reservoir causes a reduction in the flow velocity and decreases turbulence thus causing the gradual deposition of those sediments carried by the stream and finally diminishing the reservoir storage capacity. sedimentation also affects the surface area of the reservoir by reducing water depth and favoring the development of aquatic plant growth. angerb reservoir constructed in early 1980, to supply water for gondar town people could not be serving up to the expected design period because of siltation (admasu, 2005). this implies that the megech reservoir which is going to be constructed around the same area is expected to face such sedimentation problems. from this experience, it has become a serious concern to determine the trends of streamflow and sedimentation on megech reservoir catchment for planning, design, and implementation of numerous national water resource development projects in the area. there is also a knowledge gap concerning the interdependence between the sediment production and watershed treatments on different temporal and spatial scale in the study area. due to the above reasons, there is a need for hydrological research of megech reservoir catchment which could support improved catchment management programs to safeguard the alarming degradation of soil and water resources. since the megech dam is currently under construction phase, determining the spatial distribution of sediment yield is essential to have efficient reservoir water resource management as per the design life span of the reservoir by improving catchment management practices. the overall objective of the research was to calibrate, validate and evaluate the performance of the swat model for sediment yield modeling and to predict the total sediment load entering to megech reservoir. the research was also intended to evaluate the spatial distribution of soil erosio n for identifying and ranking erosion vulnerable sub-basins of megech reservoir catchment and to recommend management strategy. study area megech reservoir catchment area at the dam site is 394.2 km2 which is fully gauged. megech catchment upstream of the dam site is characterized as a steep mountainous watershed with a relative elevation difference of 1075 m. the elevation in the catchment has its maximum value in the north-east direction which is 2953 m above mean sea level. the lowest topography land is at the dam site, which is at an altitude of 1878 m above mean sea level. megech reservoir catchment is presently covered with six types of land covers namely bare land, cultivated land, grassland, shrubland, urban and plantation forest. cultivated land covers the highest portion of the catchment as it could be seen from the land use map. according to fao (2002) soil classification system, the major and dominant soil identified in the megech reservoir catchment are eutric leptosols, eutric vertisols, urban, chromic luvisols and haplic nitosols. as it could be seen from the soil map most of the watershed area is covered with eutric leptosols. the megech reservoir catchment area is characterized by severe land degradation situations i ndicated with excessive soil erosion in the form of sheet, rills, gullies, and land sliding, high deforestation, low vegetation cover, the decline of soil fertility and low land productivity. gullies are a frequent and permanent phenomenon everywhere, particularly on steep cultivated, grazing and open shrublands. it is evident in almost all slope classes of the catchment area that are kept under cultivation; grazing and open shrublands are exceedingly affected due to soil erosion and land degradation problems. out of the total study area close to 50% is under this threat. the climate of the megech catchment is marked by a rainy season from may to october, with monthly rainfall varying from 67 mm in october to 306 mm in july. the mean annual precipitation is about 1,100 mm in the upper part and about 1,000 mm in the lower part. rainfall over the megech catchment is mono -modal with nearly 79 % of the annual rainfall occurring in the period june – september. maximum temperatures vary from 23 ºc in july to 30 ºc in march, whereas minimum temperatures range from 11.5 ºc in january to 15.6 ºc in april & may. humidity varies between 39% in march and 79% in august. wind speed is low, thus minimizing potential evapotranspiration values between 101 mm/month in july and 149 mm/month in march (wwdse, 2008). the megech river, which is about 75 km long, has an average annual discharge of 5.6 m³/s. eighty five percent of the annual runoff occurs from july to september. the daily minimum river flow record is 4 m3/s whereas the daily maximum river flow is 160 m3/s. the total mean annual sediment load entering the megech reservoir is estimated as 461,214 t, which corresponds to 1,170 t/km2/year. megech reservoir capacity is about 182 m m3 of water. the dam is currently under construction phase and it is rock fill embankment type with a crest length of 890 m and height of 76.5m above the river bed level. the dam would allow developing around 7,311 hectares of land using irrigation, besides securing water demand for gondar town. the dam is provided with side-channel spillway and chute to discharge 662 m3 of water per second without overtopping the dam. the location map of megech reservoir catchment is shown in fig. 1. assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. 23 methods there are a wide variety of models used to estimate soil erosion. these models can be physical-based, empirical, and conceptual (farhan and nawaiseh, 2015). arc gis software and its extension, the arc swat model were used for input data preparation, analysis and modeling purpose of the research. in general, three types of data namely spatial, meteorological and hydrological data were collected for this study. the spatial data (digital elevation map, land use/cover and soil map) have 90m*90m resolution. fifteen year’s daily time series meteorological data (precipitation, air temperature, solar radiation, wind speed, and relative humidity) and hydrological data (streamflow and sediment flow) were also collected starting from jan 1-2001 to 2015. the data collected were processed until they become an input to the model used. the data processing started by defining all spatial data with the same projection and the watershed delineation. the overlay operation of the land cover map, soil map, and slope map was performed once after the slope classification was made based on the dem data. then the hydraulic response unit analysis was done for the spatial input data and the weather/meteorological data table. for the weather generator/ synoptic station all the required values were computed both manually and using helping software such as wgnmaker4.xlsm and dew02.exe program. finally, the model was parameterized by converting the results of data analysis into model parameters, then model sensitivity analysis, calibration, validation, and simulation were conducted. spatial data collection and analysis a digital elevation map was collected by the ministry of water, irrigation, and energy (mowie). flat, undulating plains, rolling plains, hills and mountainous landforms are the major topographic features of the megech dam watershed (fao, 2002). the elevation of the study area ranges from 1878 m to 2953 m a.s.l. the source of land use map shown in fig. 2 was the ministry of agriculture and rural development, a rural land management directorate. spatial distribution and specific land use parameters were required for modeling. swat has predefined land uses identified by four-letter codes and it uses these codes to link land use maps to swat land use databases in the gis interface. therefore, for the study land uses to be configured by the swat lookup table have been prepared and land use types were made compatible with the input needs of the model. fina lly, the land uses were reclassified by 4-letter swat code and their spatial distribution was prepared. the soil textural and physicochemical properties required by the swat model include soil texture, available water fig. 1 location of megech reservoir catchment in ethiopia (a) gauging stations near the study area and the location of the 29 sub-basins in the megech reservoir catchment (b) 24 assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. content, hydraulic conductivity, bulk density and organic carbon content for each soil type. these data were obtained from fao (2002) and the ministry of water resources, irrigation and energy. the shape file which describes the distribution of soil in the study area was obtained from the baseline maps available at mowie as shown in fig. 3. fig. 2 land use map of the catchment fig. 3 soil map of the catchment meteorological data collection and analysis there are six meteorological observation stations within and around the megech watershed namely aykel, gondar, ambagiorgis, chewahit, gorgora, and maksegnit. for each gauging station, the required daily meteorological data (daily precipitation, daily maximum, and daily minimum air temperature, daily solar radiation, daily wind speed, and daily relative humidity) were collected from the national meteorological agency of ethiopia (nma) from 2001 to 2015. checking the availability, quality, consistency, and homogeneity of hydro-meteorological data is imperative for any hydrological mode l study like swat. for this study detail, discussion of both spatial and temporal analysis was made on rainfall, streamflow, and sediment yield. due to its low impact on the swat application, only a simple graphical plot and visual examination was made for the remaining meteorological data. rainfall data analysis failure of the observer to make the necessary visit to the gage, destruction of recording gages or instrument failure (by mechanical or electrical malfunctioning) may result in missing data. for hydrological analysis, these missed rainfall data should be first filled with an appropriate method. for this study, missing values were estimated from other stations around the missed record station by using both normal ratio method and simple arithmetic mean method. the normal ratio method was used when the mean monthly rainfall of one or more of the adjacent stations differs from that of the missed record station by more than 10%. whereas, the simple arithmetic mean method was used when the mean monthly rainfall of all the adjacent stations is within 10% of the station under consideration. homogeneity of the selected rainfall stations had been checked by using non-dimensional values of the monthly precipitation. the homogeneity test plot shows that all of the rainfall stations used for this particular study were homogenous and their rainfall pattern was found to be monomodal with high rainfall season from july to september and low rainfall season from february to march. in this study double mass curve, spatial consistency test method is used to check the consistency of rainfall data for the research period. the spatial analyses of rainfall for all gauging stations were made for the research period (2001 -2015) and its result is located in fig 4. as could be seen from the graph comparisons of the two principal stations were made and gonder station was found to be the best representative of the catchment than aykel. hence, using gonder station as a weather generator provides better output than using aykel. rain gauges represent point sampling of the areal distribution of a storm. in practice, hydrological analysis requires knowledge of the rainfall over an area. due to its simplicity, the thiessen polygon method is used to calculate areal rainfall and is given by: assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. 25 pave = ) * ( 1  n i at aipi where pave is average areal rainfall (mm), p1, p2, p3….pn is precipitation of station 1, 2, 3…n, respectively and a1, a2, a3….an is area coverage of station 1, 2, 3…n respectively in the thiessen polygon. fig. 4 mean annual rainfall of stations in the catchment (20012015) hydrological data collection and analysis both the daily streamflow and sediment data were collected from the ministry of water, irrigation, and energy (mowie), from 2001 to 2015 (starting on jan 12001) at azezo gauging station. unlike streamflow data, sediment data records exhibit several jumps. due to the lack of continuous-time step suspended sediment records, the sediment rating curve was developed for this particular study by using the measured sediment records as a function of the corresponding streamflow values. the sediment rating curve is a widely applicable technique for estimating the suspended sediment load being transported by a river through signifying a relationship between the stream discharge and sediment concentration or load (clarke, 1994). the general relationship of suspended sediment rating curve can be written as: qs = a*qb where: qs is sediment load in t/day, q is the stream discharge in m3/s and a & b are regression constants. to work on the above formula the first task was the conversion of the measured suspended sediment concentration (mg/l) records that were collected from the mowie into sediment load (t/day) by using the following conversion formula: s = 0.0864 x q x c where: s is sediment load in (t/day), q is streamflow (m3/s), c is sediment concentration (mg/l) and 0.0864 is conversion factor. qs = 28.46*q1.213 where: q is streamflow (m3/s) and qs suspended sediment load (t/day). the relationship is known as the suspended sediment rating curve and is shown in fig. 5. swat simulation is based on the total sediment load (suspended + bed load). however, there was no measured data on bedload material. hence considering the mountainous nature of megech river it was decided that the bedload for the megech catchment would be estimated as being 10% of the suspended load (wwds, 2008). fig. 5 sediment rating curve of megech river (nr. azezo) swat model set up the megech reservoir catchment modeling was done by the swat model that is compiled using the avswatx interface (arcview gis interface for swat). the first step in the swat model setup was watershed delineation and stream network determination (neitsch et al. 2009) using the megech reservoir catchment dem and taking the center of the megech dam axis at the river bed level as an outlet point. next, the study catchment was divided into sub watersheds based on the concept of flow direction and accumulation; and sub-watersheds were further subdivided into smallest unit called hydraulic response units which consist of unique combinations of homogeneous soil, land use properties, and slope range (arnold et al., 2012). the runoff and sediment yield is estimated separately for each hydraulic response unit and routed to obtain the total value for the watershed (winchell et al., 2007). finally, weather data definition and simulation were followed by sensitivity analysis and calibration. sensitivity analysis, calibration, and validation the default simulation output in the swat model run can not be directly used for further analysis. instead, the ability of the model to sufficiently predict the constituent streamflow and sediment yield should be evaluated through sensitivity analysis, model calibration, and validation (white, 1992). performing the calibration process for all model parameters becomes complex and computationally far-reaching. in such cases, sensitivity analysis is helpful to identify and rank parameters that have a significant impact on specific model outputs of interest. the flow and sediment parameters considered by the model for sensitivity analysis are shown in table 1 and table 2 respectively. the sensitivity analysis method implemented in the swat model is called the latin hypercube one-at –a-time (lh-oat) design (van griensven and srinivasan, 26 assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. 2005). after running sensitivity analysis, the sensitive parameters were categorized into four classes based on their mean relative sensitivity (mrs). the four classes are small to negligible (0 ≤ mrs < 0.05), medium (0.05 ≤ mrs < 0.2), high (0.2 ≤ mrs < 1) and very high (mrs ≥ 1) (lenhart et al., 2002). based on this classification, both flow and sediment parameters with mean relative sensitivity value of medium to very high had been selected for calibration. for this study, the sensitivity analysis was performed from january 1, 2003, to december 31, 2009, in which the first two years (2001 and 2002) were taken as warm-up periods. model calibration is the modification of parameter values and comparison of predicted output of interest to measured data until a defined objective function is achieved (james and burges, 1982). calibration of streamflow and sediment yield was carried out at the outlet of sub-basin 29 (near azezo gauging station). model validation is testing of calibrated model results with independent data set without any further adjustment (neitsch, 2005) at different spatial and temporal scales. table 3 shows both the calibration and validation periods. table 3 calibration and validation periods for flow and sediment types of simulation period of simulation flow calibration 2001 2009 flow validation 2010 2015 sediment calibration 2001 2009 sediment validation 2010 2015 performance evaluation of the swat model three methods for performance evaluation of model predictions were used during the calibration and validation periods namely regression coefficient (r2), nash and sutcliffe simulation efficiency (ens) and relative volume error (rve). r² value greater than 0.6 is acceptable (santhi et al., 2001) and its value can be calculated by the following equation: 2 1 1 22 12 )()( ))((                n i n i ooissi n i ooissi qqqq qqqq r table 1 flow parameters for sensitivity analysis flow parameters used for sensitivity analysis unit swat_code alpha base flow recession constant day alpha_bf threshold depth of water required for return flow to occur mm gwqmn initial scs cn ii value % cn2 soil evaporation compensation factor _ esco effective channel hydraulic conductivity mm/hr ch_k2 available water capacity mm water/mm soil sol_awc threshold depth of water required for evaporation to occur mm revapmn soil depth mm sol_z maximum potential leaf area index _ blai maximum canopy index mm canmx groundwater evaporation coefficient _ gw_revap soil conductivity mm/hr sol_k ground water delay day gw_delay average slope steepness m/m slope manning coefficient for channel _ ch_n2 plant evaporation compensation factor _ epco surface runoff lag coefficient _ surlag soil albedo _ sol_alb table 2 sediment parameters for sensitivity analysis sediment parameters used for sensitivity analysis unit swat_code usle support practice factor _ usle_p average slope steepness m/m slope linear factor for channel sediment routing _ spcon available water capacity mmh2o /mm soil sol_awc soil albedo _ sol_alb exponential factor for sediment routing _ spexp soil conductivity mm/hr sol_k maximum potential leaf area index _ biomix channel cover factor _ ch_cov channel erodibility factor _ ch_erod usle cover factor _ usle_c assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. 27 where: qsi is the simulated values of the quantity in each model time step, qoi is the measured values of the quantity in each model time step, qs is the average simulated value of the quantity in each model time step, qo is the average measured value of the quantity in each model time step. ens value greater than 0.5 is acceptable (nash and suttcliffe, 1970) and its value can be calculated as follows:        n i ooi n i sioi qq qq ens 1 2 1 )( 2)( 1 where: qsi is the simulated values of the quantity in each model time step, and qoi is the measured values of the quantity in each model time step and qo is the average measured value of the quantity in each model time step. a relative volume error of less than +5 % or -5% indicates that a model performs well while relative volume errors between +5% and + 10% and – 5% and -10 % indicate a model with reasonable performance. %100* )(     qobs qobsqsim rve where rve is relative volume error in %, qsim is simulated discharge and qobs is observed discharge in each model time step. results and discussion stream flow modeling eight flow parameters with a sensitivity class of very high to medium were selected for calibration as listed in table 4. the simulated mean annual streamflow after calibration shows a good agreement with the observed data set as indicated in fig. 6. even though the pattern agreement was good for simulated and calibrated model the streamflow volume error was found to be -8.64 during the calibration period. the possible causes can be inefficient manual calibration, incorrect rainfall and streamflow record, error in estimating missed flow and precipitation data. r2 = 0.71 and ens= 0.63 were calculated. during the validation period (2010-2015) the performance of the model was evaluated and gives a value of r2= 0.79 and ens = 0.83. even though the relative volume error is somewhat large the (r 2) and (ens) value lies in the acceptable range, hence it is possible to say that the swat model was successful to simulate realistic flow with a little deviation from observed streamflow for this particular research as shown in fig. 7. fig. 6 observed and simulated streamflow for the calibration period (2003 -2009) fig. 7 observed and simulated streamflow for the validation period (2010 -2015) 28 assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. table 4 calibrated values of sensitive flow parameters r a n k f lo w p a ra m e te rs s e n si ti v it y in d e x ( m r s ) c la ss o f se n si ti v it y a ll o w a b le ra n g e o f c a li b ra ti o n c a li b ra te d v a lu e s 1 alpha_bf 1.39e+00 very high 0-1 0.091 2 gwqmn 2.56e-01 high 0-1000 360 3 cn2 9.46e-02 medium ±25 11 4 esco 9.22e-02 medium 0-1 0.91 5 ch_k2 5.32e-02 medium 0-1 0.71 6 sol_awc 5.25e-02 medium ±25 5.8 7 revapmn 5.24e-02 medium 0-1000 291 8 sol_z 5.10e-02 medium ±25 21 sediment yield modeling six sediment parameters with a sensitivity class of very high to the medium were selected for calibration as listed in table 5. unlike streamflow simulation, the mismatch gap between measured and simulated sediment yield was found to be large for default simulation. the possible cause for this variation might be the lack of enough measured sediment data used during sediment rating curve development as most of the sediment samples were not representatives of the whole simulation periods. the sediment yield was initially calibrated manually for mean annual conditions until the simulated output coincides with the measured sediment load (t/ha/year). next to mean annual sediment yield calibration the monthly time step calibration was carried out by varying sediment sensitive parameters iteratively within the allowable ranges until a satisfactory agreement between observed and simulated sediment yield was obtained. lastly monthly time step sediment yield hydrograph was developed to compare the observed and simulated sediment load values for the calibration period. the comparison between observed and simulated sediment flow for the calibration period was shown in fig. 8. disparate from calibration, the sediment yield hydrograph of measured and simulated output during the validation period shows a good agreement. this was mainly due to the availability of enough measured sediment samples taken during the validation period which later used for sediment rating curve preparation. this ensures that the observed sediment load data used for model input during the validation period were more representative and better approach to reality than the calibration period. the comparison between observed and simulated sediment flow for the validation period was shown in fig. 9. finally, measures of model performance values for sediment were summarized in table 6. the model performance standard used to evaluate the model result indicates that the model was superior in performing the trend of runoff and sediment yield in both calibration and validation periods. table 5 calibrated values of sensitive sediment parameters r a n k s e d im e n t p a ra m e te rs s e n si ti v it y in d e x ( m r s ) c la ss o f se n si ti v it y a ll o w a b le ra n g e o f c a li b ra ti o n c a li b ra te d v a lu e s 1 usle_p 2.71e+00 very high 0-1 0.81 2 slope 1.01e+00 very high ±25 6.1 3 spcon 4.86e-01 high 0.00010.01 0.00 41 4 sol_awc 3.11e-01 high ±25 15.3 5 sol_alb 5.62e-02 medium ±25 -3 6 spexp 5.26e-02 medium 1-2 1.43 table 6 measures of model performance for sediment parameters calibration (2003-2009) validation (2010-2015) r2 0.82 0.9 ens 0.77 0.81 fig. 8 observed and simulated sediment flow for calibration period (2003 -2009) assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. 29 spatial model responses to runoff and soil loss once sensitivity analysis, calibration, and validation of the model was done for both streamflow and sediment yield the next step was to simulate the model for the whole period of research baseline (2001-2015) and quantify the model response to runoff and soil loss as shown in table 7. the catchment was subdivided into 29 sub-basins as shown in the location map. the erosion risk map was developed depending on the severity classes adopted from haregeweyn et al. (2017). based on haregeweyn et al. (2017) recommendation the soil loss (t/ha/year) < 5 was very slight, 5-15 slight, 15-30 moderate, 30-50 severe and > 50 was very severe. the map showed that 33.25 % and 66.75 % of the catchment area was experienced slight and moderate soil erosion rate respectively. on average 12.33 t/ha mean annual sediment load gets into the megech reservoir. the overall spatial distribution of the soil erosion on the catchment was summarized in table 8. subbasin 7, 25, 27, 18 and 29 contribute the highest mean annual sediment load to the megech reservoir and are identified as the most erosion vulnerable sub-basins of the megech reservoir with 17.8, 16.86, 15.97, 15.91 and 15.74 t/ha/year soil loses respectively. table 7 model response to runoff and soil erosion runoff (mm) sediment yield (t/ha) base flow (mm) total water yield (mm) 282 12.33 504 786 the land use/land cover map shows that the catchment is covered by 64.34 % of cultivated land, 1.19 % of plantation forest, 7.8 % of grassland, 20.59 % of shrubland, 2.95 % of bare land and 3.14 % of urban. most of the erosion of vulnerable sub-basins are covered with cultivated/agricultural land uses. an agricultural land is exposed to pulverization of the soil during the frequent tillage practice in the study area and increases the erosion rate as it could be seen in the field visit. the soil map shows that the catchment is covered by 84.35% eutric leptosols, 9.47% haplic nitisols, 3.77% chromic luvisols, 1.04 urban and 1.38% eutric vertisols. table 8 spatial distribution of sediment yield in megech reservoir catchment s u b -b a si n s a re a ( h a ) m e a n a n n u a l su rf a c e ru n o ff ( m m ) m e a n a n n u a l so il l o ss ( t) s e d im e n t y ie ld ( t/ h a ) r a n k 1 1419.8 233 14,354 10.11 23 2 1889.9 230 18,710 9.9 23 3 324.04 204 2,262 6.98 28 4 2272.4 207 25,224 11.1 22 5 2178.1 235 18,100 8.31 25 6 1109.1 221 10,159 9.16 24 7 1292 301 22,998 17.8 1 8 262.24 271 2,145 8.18 26 9 613.84 352 7,992 13.02 14 10 861.88 303 12,825 14.88 8 11 1307.8 216 15,471 11.83 19 12 1870.7 185 25,086 13.41 10 13 837.66 315 9,809 11.71 20 14 90.197 236 1,341 14.87 9 15 901.13 261 11,904 13.21 12 16 1216.8 253 8,652 7.11 27 17 3091.7 390 39,110 12.65 16 18 1332.1 262 21,194 15.91 4 19 1038.1 387 16,070 15.48 6 20 1631.1 271 21,824 13.38 11 21 238.85 328 3,580 14.99 7 22 345.75 311 4,522 13.08 13 23 1090.7 290 12,118 11.11 21 24 1393.9 327 17,717 12.71 15 25 6925.9 390 116,771 16.86 2 26 983.81 250 6,306 6.41 29 27 2047.8 322 32,703 15.97 3 28 379.16 296 4,489 11.84 18 29 472.7 331 7,440 15.74 5 average basin value: 282 17,616 12.33 fig. 9 observed and simulated sediment flow for the validation period (2010-2015) 30 assfaw 2019 / journal of environmental geography 12 (3–4), 21–31. eutric leptosols are the dominant soil type in these areas as it could be seen in the soil map of the study area and the relief is hills type, which could be also another reason for the increments of soil erosion. considering the above land use, soil type, slope, and relief of erosion vulnerable sub-basins cut off drains, fallow land, contour ploughing, fanya juu terraces, soil bunds combined with trenches and trees could be the possible management strategies to reduce the sediment yield in the catchment. conclusions as per the objective of this particular research the spatial distribution of sediment yield was estimated and erosion vulnerable sub-basins were ranked and analyzed statistically by using a semi-distributed model called swat. the model performance criterion used to evaluate the model result indicates that the model was superior in performing the trend of sediment yield in both calibration and validation periods. the simulated output of the model shows that 12.33 t/ha/year sediment load gets into the megech reservoir. but, megech dam design report shows as the dead storage capacity of the dam was designed by considering 11.7 t/ha/year sedimentation rates. hence, the designers are recommended to revise the dead storage capacity of the reservoir to include the incremental rate of sedimentation. beside this local governments and policymakers are highly recommended to implement appropriate management strategies such as cut off drains, fallow land, contour ploughing, fanya juu terraces, soil bunds combined with trenches and trees on that erosion vulnerable sub-basins to maximize the design span life of the megech reservoir through reducing the sediment yield generated from the catchment. the major limitation during this research work was lack of bedload data and continuous measured suspended sediment data. only a few sediment concentration measurements were available during different years. the best option for this problem was to generate the daily sediment data from sediment rating curves developed by using available measurements. therefore, to get bettersimulated sediment output that approaches the actual measured data responsible bodies are recommended to record frequent and reliable sediment data. finally, this study does not consider a scenario changes to compare the corresponding changes in streamflow and sediment yield. but, different variables such as land use land cover changes, climate changes, and management activities might have a significant impact on streamflow and sediment yield of the research area. hence, future researchers are highly recommended to consider these variables for estimating the corresponding impacts on streamflow and sediment yield. acknowledgment i would like to express my deep gratitude to the staff of the ministry of water, irrigation, and energy (mowie) and the national meteorological service agency (nma) for providing access to data on hydrology and meteorology respectively. international water management institute (iwmi), water works design and supervision enterprise (wwdse) and ministry of agriculture and rural development (moard) of ethiopia are duly acknowledged in availing the necessary spatial data. i am also thankful to 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white, s.m. 1992. sediment yield estimation from limited data sets: a philippines case study: ph.d. thesis, university of exeter, uk. winchel, m., srinivasan, r., di luzio, m., arnold, j. 2007. arc-swat interface for swat users guide. blackland research center, texas agricultural experiment station, and usda agricultural research service. woldemariam, g.w., iguala, a.d., tekalign, s., reddy, r.u. 2018. spatial modeling of soil erosion risk and its implication for conservation planning: the case of the gobele watershed, east hararghe zone, ethiopia. land 7, 25. doi:10.3390/land7010025 zerihun, m., mohammedyasin, m.s., sewnet, d., adem, a.a., lakew, m. 2018. assessment of soil erosion using rusle, gis and remote sensing in nw ethiopia. geoderma regional 12, 83–90. doi: 10.1016/j.geodrs.2018.01.002 https://doi.org/10.3390/su7066523 https://doi.org/10.3390/su7066523 introduction study area methods spatial data collection and analysis meteorological data collection and analysis rainfall data analysis hydrological data collection and analysis swat model set up sensitivity analysis, calibration, and validation performance evaluation of the swat model results and discussion stream flow modeling sediment yield modeling spatial model responses to runoff and soil loss conclusions acknowledgment references journal of environmental geography journal of environmental geography 7 (3–4), 21–30. doi: 10.2478/jengeo-2014-0009 issn: 2060-467x grain size distribution of stabilised aeolian dune sediments in inner somogy, hungary katalin györgyövics*, tímea kiss , györgy sipos department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: katalingy87@gmail.com research article, received 24 july 2014, accepted 15 september 2014 abstract in inner somogy the former researches concluded that the grain size of stabilised aeolian dunes decreases from north to south fitting to grain size distribution of the alluvial fan the dunes were built of and to the prevailing wind. however, the trend is not so evident, if considering the dune types and sand moving periods. the aim of this paper is to analyse the grain size distribution trends from the point of view of (1) different dune classes, (2) osl age and (3) general morphological characteristics of the region. during the analysis the grain size distribution of 345 samples from 17 cores (120-300 cm in depth) was determined, and 15 osl samples were dated. according to the results, the material of simple forms and level 1 dunes (these are the lowest dunes on the surface of the alluvial fan) becomes finer southward, in accordance with the structure of the alluvial fan and prevailing wind direction. similar trend applies for level 2 dunes (which were formed on the top of level 1 dunes), but it does not apply for level 3 dunes, which are situated on the top of other dunes. it seems that the grain size is inversely proportional to the size of a dune and its age, thus younger and smaller dunes have coarser and less well sorted material. the sediments of the oldest, large parabolic dunes are the finest, younger, medium size parabolic forms have fine material, and the youngest hummocks contain the coarsest sand. the decreasing grain size towards south is the most apparent along longitudinal residual ridges, while within parabolic dunes the wings contain finer material than their elevated head. keywords: inner somogy, grain size distribution, aeolian sediment, parabolic dunes, sorting process introduction grain size distribution analysis is one of the most commonly used methods in aeolian sand research (bagnold, 1937; lancaster, 1995; zhu et al., 2014), therefore several techniques and scales were developed (sahu, 1964; wang et al., 2003; blott and pye, 2012). aeolian sands are well sorted; the dominant grain size varies between 125-500 µm (bagnold, 1937; borsy, 1961). on dune heads, sediment is better sorted and finer than in interdune areas, the largest grains remain in deflation hollows (zhu et al. , 2014). on a sand area evolved by reworking an alluvial fan, the characteristics of the source material control the grain size, prevailing wind barely can modify it (liu et al., 2014; zhu et al., 2014); only sorting is improved through transportation (zhu and yu, 2014). based on surface sediments from northern china, nottebaum et al. (2014) determined that coarser aeol ian grains appear more likely in lower elevations while finer sediments in higher elevations above sea level. dunes of various ages in india show similar grain size distribution and consist mainly of fine sand (120 -250 μm, reddy et al., 2013). inner somogy (southwest hungary) was an alluvial fan of the danube and its tributary, and the all uvial material was reworked by wind during the neogene. earlier researches investigated the grain size distribution of the alluvial sediments and aeolian sands too. marosi (1970) separated fluvial and aeolian sands based on fauna remnants, cross-bedded sediment structure and surface characteristics of the single grains. according to his research, fluvial sediments of east inner somogy become finer from east to west and also from north to south (in accordance with the construction mechanism of alluvial fans). thus, in the northern part 11% of the aeolian sediment is ≥1400 µm, while in the southern part its proportion is only around 2%. also the distribution curve mode gradua lly shifted to the finer fractions towards the southern region (320-630 µm in north and 60-100 µm in south). separating fluvial and aeolian sands applying electron microscope studies lóki (1981) showed similar results. he noted that fluvial sediments of the northern region are coarser, as samples contain 50 -60% of medium and coarse sand (>300-200 µm), and grains above 3000 µm were also found. in east inner somogy towards south, the proportion of the fine and very fine sand fraction (200-50 µm) gradually increases to 80%. the most common grain size is 320 100 µm, and 200-100 µm. increased proportion of fine particles towards south can also be detected in aeolian sands, as during the aeolian transport the sediment became sorted and 22 györgyövics et al. (2014) refined (marosi, 1970). in northern areas, the proportion of fine sand fraction (60-100 µm) decreased in the aeolian sediments compared to alluvial fan mater ial, since wind presumably blown it southward. in south, loessy sediments (≤60 µm) accumulated, the predominant fraction remained 100-200 µm, its proportion even increased from approx. 30% to approx. 50% (marosi, 1970). in east inner somogy in the sand dunes the proportion of fine sand is larger than of medium sand (lóki, 1981). during a sedimentological research marosi (1970) derived results from regional average values and did not investigate grain size di stribution differences of dune types. lóki (1981) did not study the grain size distribution differences between different aeolian forms, however he described dunes on the leeward side of marcali loess ridge covered by loessy-sand (20-50 µm: 15-25%), and therefore, concluded that sand movement was not continuous. this research aimed (1) to study the sedimentological characteristics of dune classes identified in the region by györgyövics and kiss (2013); (2) to eval uate the grain size distribution changes within the whole sand dune area and within a single dune, and (3) to analyse the connection between aeolian material and osl age of dunes. study area the most western sand dune area in the carpathian basin is inner somogy (3000 km2), situated on the south-western part of the basin between lake balaton and river dráva (fig. 1). during the pliocene, the danube and its tributaries flowed into the remnant of pannonian lake (slavonian or paludina lake) and built an extensive alluvial fan (ádám et al. , 1981). then as north of inner somogy, the keszthelygleichenberg divide uplifted in the late pliocene (pécsi, 1959) or early pleistocene (ruszkiczayrüdiger et al., 2011), the danube shifted northward and occupied its current west-east flow direction between bratislava and budapest (borsy et al., 1969). later even the smaller rivers abandoned the alluvial fan, thus aeolian processes reworked the surface during the weichselian (marosi, 1970). throughout the more humid holocene, sheetwash, gully and valley formation were widespread (marosi, 1970). in the development of the area sebe et al. (2010) emphasised the role of wind erosion and described the landscape as a complex yardang system, yet the age and process of sand dune formation and their possible holocene modification was not studied in their work. in the early twentieth century, cholnoky (n.d.) described the area as a single, large blowout ‒ residual ridge ‒ hummock form. later marosi (1967, 1970) mapped several smaller blowout ‒ residual ridge ‒ hummock systems and identified superimposed dune generations. lóki (1981) edited a large scale (1:100,000) geomorphologic map of the region, indicating complex dune systems, longitudinal ridges and blowouts. the latest research (györgyövics and kiss, 2013) identified largeand medium-size parabolic dunes with different degree of infilling, hummocks and wing fragments. the described forms occur as single dunes or as part of a three-level superimposed hierarchy system. from periglacial perturbation exposures inside the stabilised dunes, earlier researches (pécsi, 1962; marosi, 1870; lóki, 1981) presumed widespread aeolian sand formation since early wechselian until upper pleniglacial. however, recent osl measurements (kiss et al., 2012) indicate to late glacial dryas phases as the main active aeolian period, and local deflation events during the preboreal and boreal phases, and human induced sand movements in the subboreal phase and in the 17 th -18 th centuries. fig. 1 the study area is located in southwest hungary, in east inner somogy. the sampling sites (k and d) were grouped based on their location within the region. nowadays the mean annual temperature is 10-11°c (tjan= -1°c, tjul= 20-21°c, dövényi, 2010). the annual precipitation is 700-800 mm, 150-200 mm higher than in the other large sand dune areas on the great hungarian plain. prevailing wind direction is northwardly, however, south-westerly winds are also abundant. the predominant wind speed is 2.5-3.5 m/s which is not sufficient to trigger recent aeolian activity (marosi and somogyi, 1990). human impacts date back to the iron age since the area has been populated (zatykó et al., 2007). the natural hydrography has been severely modified by draining swamps, building canals and constructing fish-ponds. only remote depressions are occupied by interdune lakes, marshes and alderswamps. the natural vegetation of the area is hornbeam-oak forests with juniper, however on large areas agricultural activity dates back to centuries (iványi and lehmann, 2002). grain size distribution of stabilised aeolian dune sediments in inner somogy, hungary 23 methods altogether 17 boreholes (120-300 cm deep) were drilled in inner somogy mainly on the heads of parabolic dunes. samples were collected from every 10 cm for grain size distribution analysis. the sampling sites were chosen to include superimposed and simple dunes from each morphological class, and three boreholes from a single residual ridge. meanwhile, to date the age of the aeolian forms samples were collected for optically stimulated luminescence (osl) dating from the bottom of boreholes or at each 1.0 meter. grain size distribution analysis of the 345 collected samples was carried out by analysette 22 microtec plus laser diffraction analyser. as the measurement range of the equipment is 0.008-2000 µm, particles larger than 2000 µm where removed by sieving, and percentage values were modified in accordance with fraction weight. combined udden-wenthworth scale was used for classification (blott and pye, 2012). profile figures were created in tilia graph where cluster analysis was also applied to facilitate the identification of zones and layers. the following statistical parameters were calculated according to the method of folk and ward (1957) in gradistat (blott and pye, 2001): mode, which is the local maximum of the grain size distribution curve; mean (mz), which is the arithmetic mean of the three thirds of the grain size distribution curve (folk and ward, 1957); grain size values at different cumulative percentages: d25 is the lower quartile of the grain size distribution curve, thus it is the diameter which separates the finer 25% of the grain population from the coarser 75%. d75 is upper quartile of the grain size distribution curve. d90 is the diameter size from which 90% of all sizes are smaller and 10% is larger. based on the difference of the values of d75 and d25, the degree of sorting could be estimated. however, it is important to note, that this is not equal with sorting calculated as statistical standard deviation. in this case, the smaller difference between the values of lower and upper quartiles refers to better sorting. in this research, grain size distribution variances of dunes in different hierarchy levels and morphome tric classes were analysed. based on mean (mz) values the coarsest samples were chosen from each profile and only these were included in the regional compar ison. results the studied borehole profiles were classified according to the morphometric class of the dune they were deepened in. the most typical profile of each class is presented here in details, first the largest thus the oldest dunes will be introduced, and then the smaller and younger forms. large parabolic dunes these are the largest dunes of the region; therefore they form the base of the dune association. they are 1-10 km long along the crest, located in the accumulational zones and sometimes superimposed on each other. based on the degree of infilling (sediment supply) unfilled and partially filled subclasses were identified. they consist of several different sediment layers which indicate that these dunes were formed during more than one aeolian period. for example in the profiles of dune heads (d3, k12, k13) a coarser sand layer is intercalated by two finer sand layers, while on the windward slope (k8) and wing (d5) the finest grain size is at the bottom of the profile, and the grain size distribution gradually becomes coarser towards the surface. the profile d3 was made in a head of a large parabolic dune. the samples contain 77% sand in average (fig. 2), within the sand fraction the predominant grain size class is fine sand (34 -56%). based on grain size variation three zones were identified. the bottom zone i. (210-155 cm) contains some coarse sand (0.5-1.1%), the proportion of medium sand gradually decreases (from 41% to 14%), while fine sand increases from 34% to 56% (d 90mean = 336 µm). within this zone two layers of higher sand proportion were also defined. the grain size distribution of zone ii. (155-65 cm) is relatively homogenous (d 90mean = 335 µm), a peak (38%) in medium sand proportion (85 -95 cm) divides it to three layers. in zone iii. (65 -30 cm) probably due to soil development processes, the silt and clay content increased (32-36%, d90mean = 280 µm), but well distinguishable layers were not found. two osl samples were dated from this profile. the age of the sample from 200-210 cm is 17.42±2.77 ka indicating late pleistocene sand movement when coarse grained sand was deposited (d 90mean = 349 µm). the age of the upper sample (100-110 cm: 13.43±2.08 ka) indicates late glacial aeolian activity. the finer layers (i/2-4) between the two dated samples are probably paleosols developed in the bølling and/or allerød interstadials between the two dated stadials. the upmost zone was deposited during a younger aeolian phase; its homogeneity refers to fast sedimentation within a short aeolian activity period. the grain size distribution of profile k13 is slightly different, as it was dissected to three zones: the middle zone (95 175 cm) contains the coarsest sand (d 90mean = 363 µm), the lower zone i. (d90mean = 332 µm) and upper zone iii. (d90mean = 343 µm) are only slightly finer. this form is younger than the other dated large parabolic dunes, as its osl age (k13/200-210 cm) indicates preboreal aeolian activity (10.77±0.71 ka). the d5 coring represents the material of the wing of a large parabolic dune. the sediment samples get coarser towards the surface (190 cm: d 90 = 218 µm, 70 cm: d90 = 312 µm). osl sample from 180-190 cm indicates 17.76±4.07 ka old sand movement, similar to the osl sample of d3 profile at 200 -210 cm. however this wing profile is much finer grained (d5/180-190 cm: d90 = 218 µm, d3/200-210 cm: d90, = 24 györgyövics et al. (2014) 349 µm). the material of the windward slope of a large parabolic dune (profile k8) also becomes coar ser towards the surface (zone i. d 90mean = 174 µm, zone ii. d90mean = 243µm), similarly to profile k12 where medium sand proportion in zone i. is 4-13%, but in zone ii. it rises to 17-39%. however, here a significant sand peak was also defined. medium-size parabolic dunes medium-size parabolic dunes are an order of magnitude smaller than the large parabolic dunes, as the length of their crest varies between 1.0 and 0.16 km. some are located in the accumulational zones superimposed on the heads of large parabolic dunes; others are in the transportational-erosional matrix and often form a row of dunes perpendicular to the prevailing wind direction. their degree of infilling (filled, partially filled, unfilled) indicates various amount of sand supply during their formation. their material is more homogenous, as the profiles show less variation than of the large parabolic dune profiles. the minor differences among the samples refer to repeated aeolian activity. the fine-grained layers of some profiles (k7 and k11) possibly refer to weathering caused by ground water or to soil development processes. these forms are simple dunes without large elevation differences, thus the lack of superimposition allowed the ground water variations to have an effect on sediments. however, similar weathering processes cannot be detected in the material of the superimposed level 2 or level 3 dunes (profiles d2, k1 and k2) located in the accumulational zones. d2 coring deepened into a filled medium-size parabolic dune in hierarchy level 3. the sand proportion of the samples is over 70% (fig. 2), where fine sand fraction is the predominant (≥ 40%). based on the variations of fine and medium sand proportions, two zones were defined. in zone i. (280-165 cm) the samples contains 25-36% (d90mean = 336 µm) medium sand fraction, while in zone ii. (165-0 cm) only 17-25% (d90mean = 302 µm). within the two zones, finer and coarser layers can be found. three osl samples were dated from this profile. samples from 270-280 cm and 200-210 cm date back to the late pleistocene (12.49±3.68 ka and 13.86±1.93 ka). as all along zone i. the grain size characteristics are similar, all layers were probably deposited during late glacial sand movements. the d3/100-110 cm osl sample revealed similar age (13.43±2.08 ka). the grain size distributions of the dated samples of the two profiles are similar (d2/200-210 cm: d90 = 339 µm, d2/270-280 cm: d90 = 321 µm, and d3/200-210 cm / d90 = 349 µm), indicating identical wind regime and similar environmental conditions at the time of their formation. the uppermost osl sample from d2 profile (d2/100-110 cm) refers to boreal sand movement (8.24±1.24 ka). as this zone has relatively homogenous fine-grained samples, presumably all the 160 cm deep layer of the zone i. was deposited within a short period. k1 drilling represents an unfilled medium-size parabolic dune from hierarchy level 3. all along the profile the sand content is higher (80-92%) than in profile d2. here three zones were identified, as the sandy materials were intercalated by a fine-grain layer, where the silt and clay content increases 15-20%. fig. 2 grain size distribution of profiles from each morphometric class, where d3 represents the head of a large par abolic dune, d2 represents a medium-size parabolic dune, d1 is a head of a hummock, k5 represents a residual r idge and k10 a deflation hollow grain size distribution of stabilised aeolian dune sediments in inner somogy, hungary 25 however, the profile of k2 was made in a filled medium-size parabolic dune in hierarchy level 2, it is similar to the material of the large parabolic dunes. the lower zone i. is finer grained (d90mean = 316 µm) than zone ii. (d90mean = 362 µm). the proportion of the medium sand varies considerably therefore 8 and 7 layers were defined respectively. in i/6-8. layers the silt and clay content was high, indicating soil development processes, thus they refer to a possible paleo-surface. an osl sample taken from k2/260-270 cm refers to subboreal aeolian activity at 2.99±0.19 ka. from other blown sand territories of hungary similar age of sand movement was identified (danube tisza interfluve: sipos et al., 2009; kiss et al., 2008; and nyírség: kiss and sipos, 2008), and related to bronze age anthropogenic activity. unlike earlier profiles presented here, the profile k7 is extremely rich in silt and clay. it was drilled in the head of a simple, partially filled medium-size parabolic dune. however, in zone i. sand content is relatively large (63-74%), then it is reduced to 44-67% in zone ii., finally it increases to 69-81% in zone iii. where silt-rich (32% and 43%) layers were intercalated between the sand layers. the preboreal age (11.11±0.64 ka) of the osl sample from k7/200-210 cm is very close to the age of profile k13/200-210 cm (10.77±0.71 ka). similarly to profile k7, the middle zone of profile k11 is also rich in silt (52-77%) framed by sandy lower and upper zones. k11 core was deppened in the head of a simple, filled medium-size dune. the increased silt and clay content might refer to soil development or caused by the effects of ground water variations. hummocks hummocks are the smallest crescentic forms (crest length is less than 160 m). they are generally eleva ted and located in groups superimposed on larger forms. their material is relatively homogenous, thus it was probably accumulated within a short time. these dunes are very young, anthropogenic activity in historical times triggered their formation. the d1 coring was made on the head of a hu mmock superimposed in hierarchy level 3. its sand content is high (71-96%) with the predominance of medium and fine sand (24-51% and 32-50% respectively; figure 2). the profile was dissected to three zones and within the zones 2-4 layers were identified. in zone i. (280-195 cm) the medium and fine sand grain size classes are the most common (d 90mean = 362 µm). this zone contains two coarser sand layers (sand proportion is 85% and 87%), and two finer grained layers (sand content is 75% and 71%). in the middle zone ii (195-85 cm) the clay content slightly increases (from 4-9% to 7-10%), therefore the mean grain size is considerably finer (d 90mean = 342 µm). the bottom of the zone is nearly homog enous as sand proportions are between 71 -76%, while in the upper part (105-95 cm) the proportion of sand abruptly rises to 83%. in the topmost zone iii. (85 30 cm) the coarsest sandy layers were deposited (d90mean = 425 µm). the largest grains were found in the lowermost layer (d 90mean = 504 µm), which was then covered by a finer (d90mean = 386 µm), then a coarser (d90mean = 412 µm), and another finer (d 90mean = 371 µm) layer. three osl samples were dated from this profile which all gave a very young age: 0.30±0.07 ka, 0.30±0.06 ka and 0.23±0.03 ka. north from the windward slope of the dune, a well -defined blowout is located. presumably, this is the source area of the sediment deposited in the hummock. probably the deflation was the result of human infl uence (grazing or bush burning). the three grain size zones refer to at least three deposition periods, but due to the measurement range and available error levels of osl dating, the exact time of the sand movement phases cannot be specified. three aeolian periods within approximately 130 years, during the 17 th and 18 th centuries can only be concluded. longitudinal form longitudinal ridges are elongated, quazi -linear forms which appear in various sizes (length: 35 -5600 m). numerous ridges are scattered all over the study area, some are simple dunes, but many are superi mposed on large or medium-size parabolic dunes. wing fragments or residual ridges could only be identified by their individual stratigraphic characte ristics and age. on the western part of the region a longitudinal form stretching from north to south was sampled at three boreholes along the longitudinal axis. the studied form is covered by sandy silt and silty sand, and this sandy material becomes coarser and thinner downwind. the topmost layer of the sandy zones at the bottom of each profile has the coarsest grain size, referring to the existence of a paleo-surface where larger grains remained as the result of aeolian deflation. this stratigraphic chara cteristic is typical of residual ridges. in the middle part of the residual ridge, at the k5 profile two sediment zones were identified. the lower zone contains high proportion of sand fraction, and it is divided by a sharp boundary from the upper, siltand clay-rich zone (fig. 2). in the bottom zone (250-135 cm) the proportion of sand fraction grad ually decreases from 97% to 49%, meanwhile the medium-sized sand fraction completely disappears (d90mean = 235 µm). the proportion of silt and clay abruptly increases to 14% at 235 -225 cm, then decreases (3%) again, and only gradually rises up to 51%. these variations define four layers in zone i. in the upper zone ii. (135-0 cm) the silt fraction dominates (53-73%, d90mean = 110 µm), however, in the topmost layer the proportion of the sand fraction slightly increases (35-41%). for osl dating the sandy i/4 layer (170-180 cm) and the loess-like ii/1 layer (90-100 cm) were sampled. the sandy sample revealed the oldest age (21.22±1.54 ka) dated in the region. these data support our assumption that this form is a residual ridge formed during the deflation of the previously stable surface while in the central part of the region large parabolic dunes developed (e.g. d3: 17.76±4.07 ka). the age of the approxi26 györgyövics et al. (2014) mately 130 cm thick loess-like cover is 13.3±0.74 ka, determining the same age as d2/200 -210 cm, d2/270-280 cm samples and d3/100-110 cm. it suggests that at time, when in the southern part of east inner somogy medium size parabolic dunes formed, simultaneously at the margins aeolian dust (loess) covered the residual ridge. similar loess accumul ation was also identified at the margins of other large aeolian areas in hungary (borsy, 1987). deflation hollows deflation hollows are located in the northern foreground of accumulational zones, which are the lar gest negative landforms here (area: >8 ha). they are built of alternating sandy and silty sedimentary la yers. in the hollows after the aeolian activity the groundwater level increased, thus swamps and wetlands evolved, which were covered by varying thic kness of sand during further aeolian phases. at the northern sampling site (k3) greater number of sandy and finer sediment layers was found than in south, while in the southern sampling site (k10) the sand layers are thicker. unlike previous profiles, at the k10 sampling site (fig. 2) gray-coloured sand was found, which presumes dissimilar processes and the role of diverse post-sedimentation influences. the zone i. (300 -175 cm) contains 75-81% sand (d90mean = 287 µm), within the zone four sandy layers indicate repeated aeolian activity. in the zone ii. (175 -145 cm) fine grained layer was deposited (d 90mean = 166 µm) with high silt proportion (44-66%). in the topmost zone ii i. (145-0 cm) the proportion of fine and very fine sand is higher than in the bottom zone (d 90mean = 244 µm), while its silt proportion gradually increases towards the current surface (from 16% to 46%). probably, the silty layers of zone ii. and zone iii/2 deposited in a swamp, where intensive weathering facilitated co ncentration of silt. the coarsest layers are i/6 -8 which could represent the maximum deflation level. later, a swamp was covered by blown sand layers which facilitated soil development and wea thering processes took place. the only osl samples collected at the bottom of the profile (280-290 cm) is currently under laboratory analysis. discussion regional analysis earlier researches (marosi, 1970, lóki, 1981) found that the fluvial sediments of the alluvial fan and co nsequently the reworked aeolian material become finer southward. for the regional analysis the coarsest sa mples of each profile were chosen (based on mean va lues) and their d90 values were used. the samples were collected from five well recognisable regions, therefore they were examined in five (from northern to southern) location groups (fig. 1). besides the variance in these location groups, grain size distribution of hierarchy levels and morphometric classes were also studied. on higher elevation the deposition of fine mat erial is more common, while coarser sediments are more abundant on less elevated areas. however, data derived from the 17 study sites are not significantly different, as fine samples were also found in lower laying areas (fig. 3). fig.3 the d90 values of the coarsest samples from each profile plotted against elevation above sea level of the sampling site clear trend cannot be identified either by plotting the elevation of the coarsest samples against the first mode values of their grain size distribution curves (fig. 4), however only six different first mode values are present. this presumes that the sediments depo sited during at least six aeolian erosional accumulational periods each characterised by different energy conditions. fig. 4 the first modes of the grain size distribution curves of the coarsest samples from each sampling site plotted against elevation above sea level as forms were grouped based on their hierarchy levels and morphometric classes, the grain size distr ibution analysis was also carried out on both classes. within the accumulational zones grain size variation trends cannot be examined, because (1) most of the 100 110 120 130 140 150 160 170 180 190 200 300 400 500 600 700 asl (m) d90 values of the coarsest sample ( µm) 100 110 120 130 140 150 160 170 180 190 150 200 250 300 350 asl (m) first modes values of the coarsest sample (µm) grain size distribution of stabilised aeolian dune sediments in inner somogy, hungary 27 sampled dunes are in the southernmost part of each accumulational zones, and (2) the sampling sites are only 1-2 km apart, therefore a lack of representativity within each accumulational zone is a concern. ther efore only changes in the whole region and within single forms were analysed. considering the grain size distribution of the whole region (fig. 5), the material in the northern part of the region is coarser (d 90=382-446 µm), then grain size decreases considerably towards the middle part (d90=243-419 µm), while it rises again in the southernmost areas (d90=242-616 µm). this contradicts the previous results, which described continuous refinement towards south. however, the coarse sandy mat erial in south could be explained by the diverse ages and morphometric characteristics of the sampled forms. the southernmost accumulation zone is the highest containing the greatest amount of blown -out material, thus deeper layers were blown out, which were probably coarser due to the texture of alluvial fan sediments coarsening downward. within hierarchy levels, the grain size of simple dunes and level 1 forms become explicitly finer downwind. the d90 values of simple dunes decreases southward from 446 µm to 242 µm, while of hierarchy level 1 from 429 µm to 249 µm. this is probably the result of grain size trends in the original material, as fluvial sediments in the substrate also getting finer from north to south. in case of hierarchy level 2 dunes the d90 grain size values also decrease downwind (from 436 µm to 430 µm and then to 303 µm). ho wever, the trend reverses in case of the elevated hiera rchy level 3 dunes, where the d 90 value in north is 382 µm, and it increases towards south to 616 µm. it could be explained by the development of hierarchy level 3 forms: they are mostly hummocks formed as the result of local deflation. the developed small blowouts ac ted as wind-tunnels where even the coarser sand fraction could be transported, and it became the building material of the hummocks. also, these are the youn gest dunes, therefore fine sediments of the surface were probably removed during earlier aeolian phases, thus the source of hierarchy level 3 dunes was the lower layers of the alluvial fan substrate, where coarser material was deposited. considering the average values of each hierarchy levels, the material of simple dunes is the finest (d90mean = 313 µm), while of hierarchy level 1 dunes slightly coarser (d90mean = 354 µm). the average values of hierarchy level 2 dunes become even coarser (d90mean = 390 µm), and the coarsest forms are in hie rarchy level 3 (d90mean = 472 µm). so the more elevated a form is, the coarser d90 values is characteristic, as the source material was blown from deeper and deeper, thus coarser and coarser layers of the alluvial fan substrate. thus, the aeolian deflation and accumul ation reversed the original stratigraphy of the alluvial fan’s surface. among the members of the large parabolic dune morphometric class, coarser and finer samples were both found, regardless of their spatial distribution (fig. 1), thus downwind refinement cannot be determined in case of the oldest forms (fig. 5). the material of medium-size parabolic dunes becomes finer southward, as their d90 values decrease from 446 µm to 246 µm. however, the southernmost sample does not fit into this trend (d90= 418 µm). in case of the studied members of the hummock morphometric class, the material of the southern studied hummock is coarser than of the northern. during the formation of hummocks, the sediment was probably transported just for a very short distance, from the open sand fig. 5 the d90 values of the coarsest samples of the sampling sites according to the hierarchy level (a) and morphometric class (b) of the sampled dune 28 györgyövics et al. (2014) patches created by human disturbance, thus the source material of that location determined the grain size characteristics of the forms. average values of the morphometric classes b ecome gradually coarser from the large parabolic dunes (d90mean = 353 µm) through the medium-size ones (d90mean = 385 µm) to the hummocks (d90mean = 499 µm). therefore as the size of the form decreases, their grain size increases, referring to limited sand supply and simultaneously denser vegetation, which restrict the spatial distribution of aeolian activity. within single forms, north to south refinement is the most emphasised in the sediments of the residual ridge sampled at three points, as here d90 values decrease from 419 µm to 336 µm and then to 241 µm. (fig. 5). considering the grain size distribution within a large parabolic dune it seems that finer material characterises the wings (d90=303 µm) and coarser sand was found in the head (d90=430 µm). it could be explained by the elevation of these sampling sites: the wing is lower, thus richer in moisture; therefore here the developed vegetation could act as effective sed iment trap, resulting in finer sediment deposition due to the increased friction. correspondence of grain size analysis and osl ages based on osl ages and grain size distribution anal ysis data, grain size characteristics of the transported sediments during the different aeolian phases could be compared. previous researches (marosi, 1970, lóki, 1981) argue that since late glacial wind velocity gradually declined, thus the extent of sand movement and also the grain size of deflated material decreased as well. in contrary, plotting osl ages and d 90 values of the samples (fig. 6) shows that older forms are characterised by finer grain size distribution, however, the statistical relation of the two variables is not e xplicit (r2=0,198). fig. 6 connection between osl age and d90 values of grain size distribution curves of the same osl samples the youngest (0.23±0.03 ka, 0.30±0.06 ka and 0.32±0.07 ka) samples have very coarse grain size distribution (d90 values are 461 µm, 401 µm and 403 µm, respectively), thus these are even coarser than late glacial (17-18 ka old) sands. the formation of the 17 th -18 th c. hummocks is probably due to human activity. at the time of the first military mapping, the area was a pasture, therefore, possibly as a result of overgrazing the closed vegetation opened and the wind started to deflate the available sand. probably, due to wind-tunnel effect the wind speed was high, thus coarse material could also be eroded and transported. however, it was transported only a very short distance and deposited soon forming hummocks. it could be concluded, that if conditions are sui table ‒ dry, open sand surface ‒ the wind is capable of transporting the coarse fraction of sand, despite of the more humid climate since the last glacial that allowed the development of a dense vegetation cover (járainé-komlódi, 2000). however, in case of disappearing vegetation cover, coarse sand could be tran sported due to wind-tunnel effect. the grain size of a sample could also be characterised by the mode of its grain size distribution curve. the plot of modes and osl ages show a similar trend as d90 values and osl age plots (fig. 7). modes of the grain size distribution curves of younger forms gradually increase from 150 µm to 300 µm, suggesting that the younger forms have higher first mode values. however, the statistical relation of the two variables is ambiguous, as correlation coefficient for the dataset is only r=-0.67. this is partly because samples with similar age show varying mode values as during an aeolian phase in different parts of the region sediments was deposited under different energy conditions and various sand availability. fig. 7 connection between osl ages of the samples and their grain size distribution curve’s mode values (black – first mode; red – second mode) second modes of the samples refer to secondary processes besides aeolian activity. for example on stabilised aeolian sand surfaces soils can develop, winnowed fine sand in dust can accumulate in leeward areas or variations in ground water level can locally concentrate fine particles and intensify weathering (profile d5, k7 and k5). 0.3±0.06 0.23±0.03 0.32±0.07 8.24±1.24 13.86±1.93 12.49±3.68 13.43±2.08 17.42±2.77 17.76±4.07 10.77±0.71 2.99±0.19 21.22±1.54 18.52±1.11 11.11±0.64 200 250 300 350 400 450 500 0 5 10 15 20 25 d90 (µm) osl age (ka) 0.3±0.06 0.23±0.03 0.32±0.07 8.24±1.24 13.86±1.93 12.49±3.68 13.43±2.08 17.42±2.77 17.76±4.07 10.77±0.71 2.99±0.19 21.22±1.54 13.3±0.74 18.52±1.11 11.11±0.64 17.76±4.07 13.3±0.74 11.11±0.64 0 50 100 150 200 250 300 0 5 10 15 20 25 osl age (ka) mode (µm) grain size distribution of stabilised aeolian dune sediments in inner somogy, hungary 29 sorting of a sample was expressed by the diffe rence of d75 and d25 values, where smaller sorting value refers to better sorted sediment. the correlation between osl ages and sorting was also examined (r2=0.742, fig. 8). the younger samples are less sorted than older ones. it refers to extensive and pro bably longer sand movement periods (báldi, 1978) during older, climate induced aeolian activity phases. in contrary, during human induced, young sand movement periods the locally disturbance enabled just limited sorting process, as the material was transpor ted within a very short distance which was not sufficient for sorting the sediment. fig. 8 connection between osl age and sorting value of the samples conclusions in the studied profiles sandy and finer grained layers alternated. probably during aeolian activity sandy material was deposited, whilst during humid phases finer material was formed due to increased weathering in swamps and soils. osl data proved several sand movement periods when the finer layers were covered by sand. the material of large parabolic dunes, simple dunes and hierarchy level 1 dunes is getting finer towards south, in accordance with the grain size changes of the alluvial fan. the grain size distribution of smaller, elevated and younger dunes is determined predominantly by local factors, such as grain size characteristics of source material and wind-tunnel effect. similar results were found in north china, where the grain size distribution of sand dunes also became finer in the deposition direction of alluvial fan in the substrate (zhu and yu, 2014). liu et al. (2014) and zhu et al. (2014) concluded that sediment characteristics are predominantly determined by the source material, therefore sand reworked from deeper layers of the alluvial fan can form small in size but coarse in grain dunes. this phenomenon was also observed in inner somogy. the d90 values show that the grain size is not finer in younger forms, as it was suggested in earlier studies (marosi, 1970), on the contrary, it is coarser. mode values of the grain size distribution curves also prove coarser sand in younger dunes. this can be a result of increased wind energy due to wind-tunnel effect, or of coarser source material. similarly increasing grain size distribution was described in the carpathian basin on the maros alluvial fan by sümeghy (2014), where pleistocene fluvial sands are finer grained than holocene sediments, which is a result of increased energy of the river and therefore coarser sediment load. this indicates that during holocene not only in fluvial, but also in aeolian environment the transport capacity increased. moreover, in inner somogy based on d 75-d25 values, younger samples are poorly sorted, presuming short aeolian periods. acknowledgements this research was supported by the otka 83561; and european union and the state of hungary, co-financed by the european social fund in the framework of támop-4.2.4.a/ 2-11/1-2012-0001 ‘national excellence program’. references ádám, l., marosi, s., szilárd, j. 1981. a dunántúli-dombság: déldunántúl. akadémiai kiadó, budapest, 704 p. bagnold, r.a. 1937. the size-grading of sand by wind. proc. r. soc. london a math. phys. sci. 163 (9), 250–264. báldi, t. 1978. a történeti földtan alapjai. tankönyvkiadó. budapest. 308. blott, s. j., pye, k. 2012. particle size scales and classification of sediment types based on particle size distributions: review and recommended procedures. sedimentology 59, 2071–2096. doi: 10.1111/j.1365-3091.2012.01335.x borsy, z. 1961. a nyírség természeti földrajza. akadémiai kiadó. budapest. 227 p. borsy, z. 1987. paleogeography of blown-sand in hungary. in: pécsi, m., velichko. a.a. 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(eds.) 2007. environmental archaeology in transdanubia (hungary). budapest, varia archaeologica hungarica 20, 239–241. zhu, b., yu, j. 2014. aeolian sorting processes in the ejina desert basin (china) and their response to depositional environment. aeolian research 12, 111–120. doi : 10.1016/j.aeolia.2013.12.004 zhu, b., yu, j., rioual r., ren x. 2014. particle size variation of aeolian dune deposits in the lower reaches of the heihe river basin, china. sedimentary geology 301, 54–69. doi:10.1016/j.sedgeo.2013.12.006 a spatiotemporal stochastic framework of groundwater fluctuation analysis journal of environmental geography journal of environmental geography 8 (3–4), 41–52. doi: 10.1515/jengeo-2015-0011 issn: 2060-467x a spatiotemporal stochastic framework of groundwater fluctuation analysis on the south eastern part of the great hungarian plain zsolt zoltán fehér department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary e-mail: feherzsolt.iamg@gmail.com research article, received 10 october 2015, accepted 1 december 2015 abstract the current study was performed on a hungarian area where the groundwater has been highly affected in the past 40 years by climate change. the stochastic estimation framework of groundwater as a spatiotemporally varying dynamic phenomenon is proposed. the probabilistic estimation of the water depth is performed as a joint realization of spatially correlated hydrographs, where parametric temporal trend models are fitted to the measured time series thereafter regionalized in space. two types of trend models are evaluated. due to its simplicity the purely mathematical trend can be used to analyze long-term groundwater trends, the average water fluctuation range and to determine the most probable date of peak groundwater level. the one which takes advantage of the knowledge of expected groundwater changes, clearly over performed the purely mathematical model, and it is selected for the construction of a spatiotemporal trend. model fitting error values are considered as a set of stochastic time series which expresses short-term anomalies of the groundwater, and they are modelled as joint space-time distribution. the resulting spatiotemporal residual field is added to the trend field, thus resulting 125 simulated realizations, which are evaluated probabilistically. the high number of joint spatiotemporal realizations provides alternative groundwater datasets as boundary conditions for a wide variety of environmental models, while the presented procedure behaves more robust over non-complete datasets. keywords: monte carlo simulation, stochastic estimation, spatiotemporal modelling, groundwater, climate change introduction the water body closest to the surface and mostly above the first confined zone is called shallow groundwater (hereinafter groundwater in this study). groundwater is a characteristic environmental element of alluvial lowlands. it is important on the one hand as a water source during the dry season for woody, as well as for deep-rooted vegetation, on the other hand, the vertically seeping groundwater means an important recharge for deep-water resources. climate variability can have significant impacts on the groundwater (treidel et al., 2012). these impacts are likely to be particularly severe when the watershed is located on an area that is predominantly disposed by the effects of altering environmental conditions, such as the great hungarian plain. as a consequence of climate change the annual distribution of the precipitation tends to become more and more extreme (ipcc, 2013). these harmful processes can be enhanced by other stresses on the hydrological system, as may occur where there are large extractions from the watershed. groundwater is vital to both environment and society, thus understanding how climate change and human activities may disturb regional water regime is exceptionally important for mitigating future water resources. the approximate state of the groundwater can be estimated by observing a temporal sequence of the groundwater depth via an observation network operating over the study area. however, the design of the observation network is critical and usually not enough dense to provide a clear view. even the wells of the hungarian measurement system, which can be considered much denser compared to other sensing networks worldwide, are located to cover 20-40 km2 each. thereby it is extremely important to select a proper method which enables accurate estimations of the groundwater state even from limited information of the measured sequences. previous studies (pálfai, 1994) have revealed that in the recent decades the groundwater of the western part of the great hungarian plain, the so called “sand ridge” between the danube and the tisza rivers is particularly affected by groundwater changes (predominantly the discharge of water resources). although these former studies reached different results regarding the ultimate causes, our gis-based quantitative analysis (rakonczai and fehér, 2015) successfully proved that the groundwater discharge is mainly influenced by altered climatic elements. our current study set both theoretical and practical goals. first, a brand new stochastic approach for the trend and variability analysis of the groundwater regime is introduced, considering water table as a spatiotemporally dynamic phenomenon. second, we attempt to quantify the groundwater changes of the recent decade in south-eastern hungary. 42 fehér (2015) study area the groundwater time series used in the current study consist of daily measured (depth to surface) water levels over the study site. the data were provided by the lower tisza district water directorate. the analysis is performed on an approximately 8490 km2 study area in the south-eastern part of the great hungarian plain. groundwater depth measurements (given in cm) are available from 207 monitoring wells between 1/1/2005 and 17/5/2015. the spatial density of the stations shows locally diverse spatial distribution (fig. 1). the length of the time series varies from 382 to 3,779 days. most of the hydrographs has at least three daily measurements, only 5 of them show huge amount of missing data. there is no significant relationship between measurement density and spatial distribution. the area consists of three significantly dissimilar units. fig.1 the study site with the operating gauge network alongside the count of available data the western side is the eastern part of the so called sand ridge. this area is significantly affected by regional scale groundwater shortage in the last decades. basin elevations range from 83 m on the tisza valley to 143 m on the southwest. the area is deposited by the river danube (the process was completed approx. 20 – 30 thousand years ago), and most of the landscape is covered by several-meter thick blown sand. thereby, in the depressions semi-bound sand dunes, salty meadows can be usually observed on the surface. according to the dominant wind direction, the characteristic nw towards se flow direction of the surface waters is determined by these relatively shallow features. these beds, however, barely carry any water, even in longer time periods. due to the elevated geomorphological position of the sand ridge, it is important to mention that groundwater resources can only be recharged by precipitation, since the opportunity of neither surface watercourses nor subsurface water flows is possible. this is the main cause of that more intense groundwater shortage which was observed in the higher area since the end of the 1970’s when the amount of the annual rainfall significantly dropped for one and a half decade. the typical discharge was around 2 metres, however on higher regions this could surpass 15 metres. in the higher areas this unfavorable situation could not be normalized even after extensive rainy periods. in the lower parts of the ridge however, the groundwater not just recovered from the water shortage, but the water level even increased thus sometimes caused harmful surface floodings after persistent rainy periods. the eastern part of the study site belongs to the alluvial fan of the river maros. basin elevations vay between 80 – 108 m. the landscape is slightly sloping towards west (to the river tisza) and the north (to the river körös). the former (approx. 2 – 18 thousand years old, sümeghy, 2015) river branches can be still observed more or less. most of the area is constituted by good quality chernozem soils, but in the deeper parts alkaline vegetation is also common. although groundwater is recharged primarily by precipitation, in this case the subsurface groundwater flow from higher regions plays significant role, through coarser, porous channel deposits of the former river beds encompass the area. the river tisza flows southwards in the axis of the some 10-12 km wide central region. this landscape is a young alluvial plain, which was continuously built by the tisza with its sediments until in the middle of the 19th century the river regulations were completed. this area is the deepest part of the great hungarian plain (as well as hungary), ranging from 75.8 m to 83 m. in the last one and a half centuries the river flows between dams. occasionally the groundwater is connected to the tisza but in common years, (when both low water levels and floods also occur) this kind of effect can be shown only within 5 km to the river. groundwater as a dynamic phenomenon estimations of large scale and long groundwater hydrographs are important boundary conditions of numerous environmental models. however, no sufficient, continuous information is available about the state of the groundwater table, thereby it has to be determined. various forms of geostatistical approaches have been developed to map groundwater table from scattered water-observations solely (delhomme, 1978; aboufassi and marino, 1983; neuman and jacobsen, 1984; dunlap and spinazola, 1984; fehér, 2012). the first attempt which involved topography as supplementary data is based on the full cokriging system (hoeksema et al., 1989), and was later improved to solve multiple usability problems (xu et al., 1992; xianlin and journel, 1999). kriging with an external drift (ked) provides an alternative to apply soft data into groundwater estimation (desbarats et al., 2001; fehér, 2015). however, kriging with local means (goovaerts, 1997), which is based on undermining the global regression of the groundwater and soft data, offers the least estimation error on some hugarian study sites (fehér, 2015; geiger, 2007). the above mentioned studies focus solely on the spatial autocorrelation of an available, contemporaneous data thus consider interaction neither on temporal (within a spatiotemporal stochastic framework of groundwater fluctuation analysis … 43 groundwater time-series on every single wells) nor on spatiotemporal (between spatially correlated hydrographs) domain. commonly, the rarer the monitoring network is or the longer the missing data period is, the more important the selection of the appropriate estimation method is. global structures of autocorrelation functions, thereby results of any geostatistical estimation are determined by (1) the spatial and/or temporal sampling structure and (2) the stationary covariance function that characterize the relationship between any available observation (journel, 1989). resource estimations and analyses of dynamic natural processes are usually investigated by comparison of spatial patterns at different time instants (eg. malvic and zelenika 2014). however long-term observation networks rarely if ever provide complete datasets, thus (1) covariance matrices of different sampling patterns differ significantly even if similar covariance functions are assumed and (2) ignorance of the local behaviour of the temporal process or a temporary extreme event (such as locally altering intensity of human activities) will cause significantly different estimation from the expected local process, thus result in false resource estimation (fehér, 2015). though the observations are neither temporally nor spatially unique, the interpolation with missing data causes modification on the covariance matrix of any selected kriging system. this leads to a somewhat semantic error, while attempting to relate groundwater levels at two different time instants. consequently, groundwater maps, which are estimated with distinct data distribution are incomparable, hence inadequate for resource or flow analysis. furthermore, the application of these data as boundary condition of any type of numerical models, leads to false outcomes. numerical models are doubtlessly able to increase reliability of water table estimations by exactly defined physical relationships between groundwater and its influencing factors. however, these approaches are computationally expensive, furthermore uncertainties of model parameterization, temporally incomplete knowledge of the varying environmental factors, and dynamic upscaling of different input datasets make difficult the application of such numerical models (fehér, 2015). in addition, the influencing factors of groundwater level proceed both temporally and spatially at different scales, so any spatial or temporal averaging or dynamic upscaling of these phenomena would change the original spatiotemporal correlations (kyriakidis and journel, 1999). groundwater, however, can be characterized in a stochastic framework (mucsi et al., 2013), by involving soft data into the estimation (fehér, 2012, 2015; geiger, 2015), like digital elevation models, even if these models are not capable to explicitly represent dynamically changing relationships between groundwater estimate and a particular influencing process. groundwater time series commonly exhibit both spatial and temporal autocorrelation. early spatiotemporal estimations treated time simply as an additional (2d+1) dimension (eynon and switzer, 1983). but, even if spatial autocorrelation is considered constant at any time instant, temporal autocorrelation may significantly differ place to place, due to different local influencing factors. consequently, conventional interpolation approaches (including any type of 2d kriging algorithm) are inappropriate to handle this kind of joint spatiotemporal autocorrelation. since the temporal domain of the groundwater observations is more densely sampled compared to the spatial domain, the estimation of missing data can be more reliably carried out on the hydrographs. the well-informed time domain can be easily exploited by either employing multivariate ar models (hosung, 1994; rétháti, 1977a, b), generalized linear models (gotway and stroup, 1997) or spectral analysis (chatfield, 1996; kovács et al., 2004, 2011), though the results cannot be interpolated over the entire domain (rouhani et al., 1992), thus these kind of spatial analysis are inappropriate to model groundwater change. the spatiotemporal variability of the groundwater cannot be accurately characterized via the above mentioned, purely deterministic models, due to the deficient knowledge of the both spatially and temporally altering physical environment and limitations of observation capabilities. since model parameters (like land use, hydrometeorological conditions, irrigation, pumping, instant state of the canal network etc.) are varying over both space and time (see fehér, 2015), long term hindcast type deterministic models, which consider these influencing factors static, would make the false sense in the modeller that his all-rounder model is perfect. in this paper groundwater is considered as a joint realization of a set of spatially correlated time series kyriakidis– journel (2001a, b), one for each grid node. hydrograph model parameters are varying in space thus capturing spacetime interactions. the difference of observed groundwater depth from these local trend estimates are regarded as a realization of a stationary spatiotemporal stochastic process. geostatistical space-time models provide a framework based on probability theory to analyze and forecast through spatial and temporal autocorrelation among available observations. in most cases a stochastic model by its own cannot explain unusual anomalies of the datasets, although that can often be explained by some other influencing physical processes. the modelling of such dynamic processes brought various, but somehow similar approaches for numerous scientific and engineering fields including hydrometeorological conditions (armstrong et al., 1993), precipitation profiles (kyriakidis et al., 2004), pressure-temparature relationships (mardia and goodall, 1993; hottovi and stechmann, 2015), variability of geophysical components (handcock and wallis, 1994; bogaert and christakos, 1997a). other similar approaches were implied in the estimation of soil moisture (goovaerts and sonnet, 1993; papritz and flührer, 1994; heuvelink et al., 1997), diseases (christakos–hristopulos 1998), environmental hazards (mateua and ignaccolo 2015), deposition of atmospheric particles (kyriakidis, 2001b; singh and gokhale, 2015) and ecological dynamics (hohn et al., 1993; de iaco et al., 2015). these procedures are common in the sense that they separate the dynamic phenomenon into (1) spatiotemporal “trend” component, which expresses some long term patterns and (2) the “residual” component that represents 44 fehér (2015) some higher frequency fluctuations around the trend component. the separation of the trend and residual component reflects a subjective decision of the modeler and the available knowledge of the phenomena. the temporal trend can be characterized by deterministic parameters for each gauge (dimitrakopoulos and luo, 1997). the spatial correlation between temporal parameters represents every spatiotemporal interaction that exists between all of the influencing factors. the residual component is induced by some small scale, rapid or interim intense effects. several studies quantified long term hydrograph patterns of the great hungarian plain. recently performed time series analyses indicated annual periodicity on about 97% of the gauges (kovács et al., 2004, 2011), which is clearly explained by annual discharge-recharge cycle (ubell, 1954). another questionable 5 and 11 year-long periodicities were also designated, which might slightly be identified by multiannual periodicity of the precipitation (kovács and turai 2004). another 14-17 year-long or even longer periodicities are also detected on a smaller set of hydrographs (rónai, 1985; rétháti, 1977), but the volume of these effects are negligible. it is important to highlight that despite these longer periodicities are “mathematically” really spotted, yet no clear, physical explanation of the underlying causes can be revealed, consequently, multi-annual periodicities must be treated carefully. the temporal profiles are spatially non-stationary, due to altering spatial intensity of the environmental factors. closer to rivers hydrograph trends usually show fewer longterm changes (bezdán, 2011) and prone to mimic water level of the nearby river. the magnitude of the annual groundwater fluctuation on steeper terrain is less than close to permanent watercourses or even on elevated reliefs. the primary reason for the latter is that groundwater continuously replenished by gravitational flow through porous media from the ridges. by contrast, the only watersource is the periodically intense rainfall in elevated areas (rakonczai, 2014). meteorological conditions show significant annual and local variability in the hungarian plain, so groundwater trends can be hardly expressed by polynomial and sinusoidal functions. long-lasting river level changes, alteration of land use, irrigation and several other factors trigger further high frequency, hardly modelable effects on the groundwater level (négyesi, 2006). therefore, it is very crucial to take the patterns of the non-stationary spatial variability of the time series into account. the spatiotemporal framework intrinsic hypothesis of the simple kriging requires a stationary variogram model, so that elimination of any relationship between groundwater observations and the spatiotemporal coordinates (deutsch and journel, 1998). comparison of resources of non-complete groundwater datasets may undermine the strong correlation (ρ = 0.98) between groundwater elevation (above sea level) and topography (fehér and rakonczai, 2012; geiger, 2015). however, the regression function can also be interpreted as a locally varying spatial trend (fehér, 2015), thus only the residuals of the regression model need to be estimated (goovaerts, 2000). instead of the spatial regression residuals, hereinafter, for practical considerations, the groundwater depth (to surface) is considered spatially detrended. groundwater time-series are decomposed into spatial and temporal trend components (eq. 1) and the fitting error of the trend function. thereafter the trend components express topo spatial as well as e(zut) = mu temporal, smoothly varying expected patterns, and the rest is considered a frequently changing, stationary e(rut) = 0 residual component. z𝐮(t) = topo + m𝐮(t) + r𝐮(t) (eq. 1) hydrograph trends can be expressed via (k + 1) deterministic functions, which are defined by an initially chosen subjective model decision (dimitrakopoulos and luo, 1997). most of the inspected hydrographs shows a downward trend, which was modelled via versatile polynomial functions. spatial patterns of each estimated bk trend coefficient theoretically expresses the locally and temporally varying intensity of some (known or unknown) fk background process. the spatial distribution of these partial trend component intensities can be expressed in two steps. first, a general function (eq. 2) needs to be fitted individually on each hydrograph, then the given function parameters can be spatially estimated, considering their variograms. m(𝐮α, ti) = ∑ bk(𝐮α)fk(ti) 4 k=0 ti ∈ tα (eq. 2) the spatial consistency for correct reconstruction of the trend field require either (1) to use identic variograms for each component regionalization or (2) to apply a linear model of coregionalization (deutsch and journel, 1998; fehér, 2012) or (3) to perform the estimation on an orthogonalized system, applying dimension reduction. in this study the principal component analysis was applied for the orthogonalization of the trend components. a set of 125 sequential gaussian simulations (deutsch and journel, 1998) of temporal trend pca-values were generated on a 156 × 106 grid with a cell size of 1 × 1 km2 for ensemble prediction. the number of realizations was determined by the spatial analysis of thickness change of the confidence intervals. the trend field for the entire spatiotemporal domain was thereafter revealed for each (𝐮α, ti) grid node using (eq. 2), since estimated bk trend coefficients are given as a median type estimation of the inverse pca transformation of each simulated random field pca score realization. since simple kriging is an exact interpolator, each trend estimate preserves its initial value at the exact gauge locations. consequently, regionalized trend ensemble values at each gauge are quasi identical to the value provided by the fitted trend function at any time instant. in addition, the station specific, detrended, zero mean r𝐮(t) residual process is quasi identical to the exact fitting error of the trend model. the ultimate goal of the spatiotemporal residual simulation is to estimate these values. the first step is, to estimate spatial distribution of the temporal autocorrelation parameters (nugget, sill and range) individually for each variogram parameter, thus each residual time series is divided by its standard deviation thereby proofing its standard normal distribution that enables simple kriging to be used in a sequnetial gaussian simulation a spatiotemporal stochastic framework of groundwater fluctuation analysis … 45 framework (deutsch and journel, 1998; mucsi et al., 2013). the standard deviation values of the calculated residual sequences were then simulated over the study site. the obtained residuals were back-transformed into the original data dimensions only after the stochastic simulation. for the sequential gaussian simulation, a spherical variogram function was automatically fitted individually on each normally distributed residual time series. the obtained nugget, sill and range parameters were then co-regionalized over the study site, by considering their spatial relationships. here we chose a simple full cokriging method for the estimation (goovaerts, 2000). in order to determine spatial autocorrelation of the gauges, the spatial variogram of the residuals was also modelled, via cross-validation (isaaks and srivastava, 1989). thereafter the residuals were considered as joint-realization of a spatiotemporal stationary process. subsequently sequential gaussian simulation (deutsch and journel, 1998) was performed at each spatial coordinates with the appropriate spatial and temporal variogram parameters, thereby 125 temporal profiles were obtained at each unsampled grid node. as the realizations of the residuals are obtained via conditional sequential gaussian simulation and added to the estimated trend ensembles, 125 geostatistical spatiotemporal distributions of daily groundwater levels were revealed. the 𝑆 = 125 alternative, equiprobable realization enables the probabilistic characterization of both the regionalized groundwater and also some simulated trend components. the following indicators were applied in the current study: (a) at each node u the 𝑧(̅𝐮) e-type estimate (the arithmetic mean) of the s simulated values 𝑧(𝑠), 𝑠 = 1, … , 𝑆 is given as: 𝑧̅(𝐮) = 1 𝑆 ∑ 𝑧(𝑠)(𝐮),𝑆𝑠=1 𝐮 ∈ 𝐷 (eq. 3) (b) at each node u the 𝜎(u) local standard deviation of the s simulated values 𝑧 (𝑠), 𝑠 = 1, … , 𝑆 is written as: 𝜎(𝐮) = √ 1 𝑆 ∑ 𝑧 (𝑠)(𝐮)]2 −𝑆𝑠=1 𝑧̅ 2(𝐮), 𝐮 ∈ 𝐷 (eq. 4.) (c) as e-type values and standard deviations of any individual grid node distributions are already revealed, the 𝑃𝑟𝑜𝑏𝑐 (𝐮) confidence interval can be calculated in any 𝑐 significance level. thicker confidence interval indicates higher estimation uncertainty: 𝑃𝑟𝑜𝑏𝑐 (𝐮) = 𝑧̅(𝐮) ± 𝑍𝑐/2 × 𝜎(𝐮) √𝑆 (eq. 5) (d) c = 0 significance level of the confidence interval reveals the median-type estimate of the grid node estimation 𝑀𝑑(𝐮) = 𝑧(̅𝐮) ± 𝑍0 × 𝜎(𝐮) √𝑆 (eq. 6.) (e) the local probability 𝑝𝑘 (𝐮; 𝑧) of the grid node estimation exceeds a given threshold can be revealed as: 𝑝(𝐮,𝑧) = 1 𝑆 ∑ 𝑖𝑘 (𝑠) (𝐮, 𝑧),𝑆𝑠=1 𝐮 ∈ 𝐷 (eq. 7) where 𝑖𝑘 (𝑠) (𝐮; 𝑧) is the indicator of 𝑧 (𝑠)(𝐮), its value is: 𝑖𝑘 (𝑠) = 1, if 𝑧(𝑠) (𝐮) > 𝑧, otherwise 0. results the groundwater level is simulated as joint ensemble images of a set of spatially correlated time series. each hydrograph is decomposed into a spatiotemporal trend and a spatiotemporal residual component. the analysis proceeds by first comparison of goodness of fit of different parametric trend functions, followed by the regionalization and spatial evaluation of the revealed trend coefficients and long term groundwater alteration on the site. dimitrakopoulos and luo, (1997) proposed three types of trend models which can be applied for time series modelling. the considered models satisfy both the tensorial invariance condition and provide a unique solution for the kriging system (deutsch and journel, 1998). these models are constituted by the sum of different degrees of polynomial and fourier components. in this study we compared each combination of models from first to third degree polynomial and first to third degree fourier models. the resulting mean average fitting error is ranging from a significant 41 to 50 cm. our analysis highlighted that the increase of the components does not necessary result a siginificant increase of the fitting performance. in this study we developed another model which involve some temporal pattern in the fitting process. the latter provided a 16-18 cm matching error, depending on the degree of the applied model parameters. consequently, the latter is more suitable to express local dynamics of groundwater changes. despite the significant matching error, the former model is still appropriate to interpret long-term differences of the groundwater dynamics. trend modelling without a temporal pattern model spectral analysis (kovács et al., 2004, 2011) indicated annual cycle as dominant periodicity on the individual time series. among analyzed function structures the first order polynomial (linear) function (eq. 8) with annual periodicity provided besides very good function match, an easily interpretable result. 𝑚(𝐮𝛼 , 𝑡𝑖 ) = 𝑏0(𝐮𝛼 ) + 𝑏1(𝐮𝛼 )𝑡𝑖 + 𝑏2(𝐮𝛼 ) ∙ cos ( 2𝜋 365.25 𝑡𝑖 ) +𝑏3(𝐮𝛼 ) ∙ sin ( 2𝜋 365.25 𝑡𝑖 ) 𝑚(𝐮𝛼 , 𝑡𝑖), 𝑖 ∈ 𝑇𝛼 (eq. 8) where 𝑏0(𝐮𝛼 ) characterizes the initial depth of the groundwater on 01/01/2005, whereas 𝑏1(𝐮𝛼 ) expresses long term recharge or discharge of the groundwater in the surroundings of any individual gauge. the 𝑎(𝐮𝛼 ) amplitude of annual periodicity express an expected groundwater fluctuation range and the 𝜙(𝐮𝛼 ) phase value designates the serial number of the date concerning to the highest groundwater level. these indicators are averaged over the considered 10-year period and both are expressed by 𝑏2(𝐮𝛼 ) and 𝑏3(𝐮𝛼 ) fourier components: 46 fehér (2015) 𝑎(𝐮𝛼 ) = √[𝑏2(𝐮𝛼 )] 2 + [𝑏3(𝐮𝛼 )] 2 (eq. 9) 𝜙(𝐮𝛼 ) = tan −1 ( 𝑏3(𝐮𝛼) 𝑏2(𝐮𝛼) ) (eq. 10) the 𝑏𝑘 (𝐮𝛼 ) intensity coefficients for each gauge were calculated individually by ordinary least squares algorithm. note that the selected ordinary least squares (searle, 1971) algorithm is a subjective model decision which completely determines the trend component estimation. the resulting components are thereafter regarded as exact data and estimated individually by sequential gaussian simulation (deutsch and journel, 1998; mucsi et al., 2013) and evaluated later. the analysis of the correlation does not indicate any significant relationship among component pairs, unless some quasi relation between long term linear trend and periodicity. in practice this may indicate the relationship between low annual periodicity and a deep water level or high annual periodicity with lower altitude. trend analysis and stochastic simulation of the groundwater using a temporal pattern the former chapter pointed out that elementary polynoms and sinusoidals provide poor efficiency in representation of frequent and uncommon hydrograph divergences by annually predicted periodicity and long term trends. in the forthcoming chapter a more accurate approach is presented. this chapter is based on the theory that a set of influence factors that affect large scale trend of the groundwater, are represented on every single hydrograph, while their intensity is varying over the site under study. the analysis begins with modelling of a common profile. this profile describes the most likely pattern, thus resulting minimal fitting error on most of the time series. first, this profile can be a particular auxiliary data, for example satellite gravimetry (gr avimetry recovery and climate experiment – grace, eg. wardlow et al., 2016). second, an intrinsic solution might be a series of arithmetic means or medians of time instants as it is presented hereafter. the joint time series model can be calculated in three subsequent steps: 1. shifting every single time series by its mean value (normalization) 2. dividing every single time series by its standard deviation (standardization) 3. eventually, standard-normal values of different time series that belong to the similar time instant are considered as a statistical set, whose arithmetic mean or median can be calculated. the series of these values constitute the finally established joint time series model (fig. 2). the obtained joint model thereafter can be successfully fitted to the majority of hydrographs, using affine transformations (rotation, translation, scaling) and fourier modulations (phase shifting). note that arithmetic mean is more sensitive to outliers that are likely present in the dataset, additionally median is a more robust method if the statistical distribution of a set is non-normal. this way median over-performs the arithmetic mean, even if it does not appear on the fitting error comparison significantly. the task is then to determine proper transformation parameters for every single 𝐮𝛼 gauge: 𝑚(𝐮𝛼 , 𝑡𝑖) = ∑ 𝑏𝑘 (𝐮𝛼 )𝑓𝑘 (𝑡𝑖 ) 𝐾 𝑘=0 𝑡𝑖 ∈ 𝑇𝛼 = 𝑏0(𝐮𝛼 ) + 𝑏1(𝐮𝛼 )𝑀𝑑(𝑡𝑖) + 𝑏2 (𝐮𝛼 )𝑡𝑖 + 𝑏3(𝐮𝛼 ) ∙ cos ( 2𝜋 12 𝑡𝑖) + 𝑏4(𝐮𝛼 ) ∙ sin ( 2𝜋 12 𝑡𝑖 ) 𝑚(𝐮𝛼 , 𝑡𝑖), 𝑖 ∈ 𝑇𝛼 (eq. 11) where 𝑏0(𝐮𝛼 ) indicate translation by y-axis, 𝑀𝑑(𝑡𝑖 ) equals to the ith value of the above discussed joint median time series model (fig. 2). the joint time series is modulated by 𝑏1 intensity along y-axis. 𝑏2(𝐮𝛼 ) parameter defines the rotation of the temporal trend profile, 𝑏3(𝐮𝛼 ) and 𝑏4(𝐮𝛼 ) expresses the phase shifting along x-axis, thereby adjusting station specific differences of the annual groundwater phase. note that higher order polynomials do not increase fit performance significantly, but their application would unnecessarily complicate the analysis. the 𝑏𝑘 (𝐮𝛼 ) intensity coefficients were calculated for each gauge individually by non-linear least squares (gauss-newton) algorithm. note that the selected nonlinear least squares (searle, 1971) algorithm is a subjective model decision thereby completely determines the trend component estimation. the resulting components are thereafter regarded exact data. although fig. 2 the applied joint median type time series model compared to a satellite gravimetry sequence (dimensionless units) a spatiotemporal stochastic framework of groundwater fluctuation analysis … 47 a very good fitting performance is achieved, the temporal trend model does not represent each hydrograph similarly. the proportion of the explained standard deviations (fig. 3) shows that some hydrographs can not be modelled well locally. in these cases, the residual model will express the proportion that does not fit to the local trend. fig. 3 proportion of the explained standard deviation by gauge mathematical interpretation of the trend functions the study proceeded by analysis of three characteristic hydrographs (fig 4.). limited information is available on kecskemét gauge at the initial period. this well is located in an elevated area of the sand ridge, close to an urban area. in the initial period the groundwater seems shallow related to other time instants, until it unexpectedly drops by 4 metres in 2007. this deep state does not change until an extreme precipitation period in 2010. it can be also recognized, that the water level does mimic long range trend pattern only when it is not deeper than 150 cm. csánytelek metering station follows the global trend until the end of 2010, thereafter the groundwater suddenly drops by 80 cm, while the hydrograph shape is still almost identical to the global trend model. probably the precipitation this time still recharges groundwater with unchanged intensity until the water level is restored to the global trend in the winter of 2012—2013. the sudden discharge might be due to some anthropogenic inventions around the gauge. the well near hódmezővásárhely shows uninterrupted groundwater trend. analyzing long term trends, hódmezővásárhely station is permanent, kecskemét observator indicates increasing whereas the csánytelek station shows a downward trend. weak periodicity can be recognized in kecskemét well in contrast to the other gauges introduced. as shown in fig 4. both fitting approach can represent long term tendencies just fine, whereas median based matching can reproduce hectic patterns of the groundwater dynamics better. while annual periodicity can somehow be reproduced, sudden uplifting of the groundwater around 2010 and 2011 can be hardly handled by pure polinomial – fourier models, due to extreme precipitation conditions (szalai et al., 2012). the approach implementing a median type temporal pattern provides definitely a more sophisticated solution fig. 4 comparison of some characteristic groundwater time series (red) and their calculated temporal trend functions using purely mathematical (right column) and median type temporal pattern (on the left). w and d indicate wet or dry periods, whereas + means an extreme event. 48 fehér (2015) compared to the one based on solely mathematical functions. consequently, the median type model is very efficient in the estimation of missing observations. by contrast, the purely polynomial – fourier type method is capable to interpret long-term (10 year) average groundwater tendencies for each individual gauge. the determined trend model parameters differ from gauge to gauge which enables to estimate long-term groundwater tendencies, by spatial interpolation of the appropriate model parameters. through the analysis of the 1-yearlong trend of every single observation of a hydrograph is represented by similar weight, consequently the fitted trend is not too sensitive to a small amount of outliers, rather more to the long period of missing data. in the present case the main analyzed factors (slope, fluctuation range and the date of the typical date of the highest water level can be determined by these restrictions. spatiotemporal estimation of the groundwater level spatiotemporal estimation of the groundwater is performed by sequential gaussian simulation (deutsch and journel, 1999; mucsi et al., 2013) of median model parameters. 125 equiprobable realizations were generated thus enabling geostatistical evaluation of the results. cross covariance matrix of the given 𝑏𝑘 parameters (not presented) highlighted some discrepancy among parameters, thus principal component analysis was performed to project them into 𝑥𝑘 orthogonal planes. in the forthcoming step a spatial estimation of the components was reconstructed from these orthogonal planes, and the values of the appropriate grid node alongside temporal coordinates were substituted into eq. 11. the analysis is proceeded by spatiotemporal geostatistical simulation of residual components. the temporal hyperparameters are modelled automatically via spherical model and regionalized by simple cokriging. the spatial variogram parameters are modelled via cross-validation. the stochastic component of the groundwater at most cases characterized by at least a half-year-long temporal range, which represents the length of the autocorrelation within the hydrograph. consequently, a half-year-long sampling interval would be enough to make good estimations on the stochastic origin changes of the groundwater. the relatively small standard deviation values indicate that the applied temporal trend function was very effective, whereas the low value of temporal sills represents the portion of the autocorrelation function which can be expressed by the applied spherical model. the higher volume means the less randomness of the time series. eventually, 125 equiprobable realizations of time series were generated for each spatial grid node using sequential gaussian simulation (kyriakidis, 2001a). the results are added node-by-node to the median-based temporal model realizations. these joint realizations were finally evaluated geostatistically by eq 3. – eq. 7. the multiple generated realizations made enable to probabilistically characterize (1) temporal change of volume, (2) estimation uncertainty, (3) spatial pattern, and (4) gravitational flow of the simulated groundwater and evaluate its environmental effects. discussion the investigated 2005-2015 period is very interesting from the hydrometeorological point ofview. since the beginning of the detailed meteorological measurements (more than 100 years ago), the two highest and also the lowest precipitation volumes have been measured during the analyzed period in hungary. the spatial average of the arrived precipitation over hungary was 938 mm in 2010, but just 407 mm in the subsequent year. at the beginning of the investigated period, the precipitation exceeded the multi-annual average (note that 2005 was the second rainiest year), but due to the preceding dry period, groundwater resources yet showed significant deficit (compared to preceding decades) on the investigated site (fig. 5). during the four subsequent dry years (alongside the well-defined annual periodicity), the depletion of groundwater resources occurred. the volume of the water shortage on the study site is at least 3 km3. in the very rainy year of 2010 the water shortage of the previous years not just recharged, but a significant water surplus was generated. consequently, inland excess water occured in multiple areas, as a result of the increase of the groundwater levels. right after an extremely wet year as an effect of an extremely dry year, a significant groundwater shortage was generated again. 2013 and 2014 were again rainier than the average, thus groundwater resources recharged again to the stage where they were 10 years ago. we found that groundwater discharge primarily affected the higher altitude areas in the preceding 40 years. fig. 5 estimated groundwater resources related to the average of 2005-2015 versus precipitation related to the average of 1970-2000 a spatiotemporal stochastic framework of groundwater fluctuation analysis … 49 however, we recognized that during the investigated 10-yearlong time period, a downward tendency continued on the study site, but, at the same time, together with long-term trends, an exciting thing was observed: in the following years the depletion is more intensely affected the lower altitudes (fig 6.). at first sight this fact can be hardly explained, but it has a very clearly identifiable cause: in the recent years the characteristic spring and early summer floods of the tisza river are absent. the river stepped out from its bed only once for a short time (in may 2013) between the spring of 2011 and the end of 2015. nearly three years ago its water level was really deep, in spite of the serbian river damming. the underground water flow probably increased towards the river, due to the permanent low water level. due to the reverse flow direction in general case in a particular part of the year (when the tisza is flooding), the groundwater resources can recharge some km wide along the river. this has importance not only because of the recharge of the water resources but also because of the tendency of minimal groundwater levels too. indeed, if the groundwater level close to the river decreases, the underground water flow from several-meter high area towards the river possibly increases. this may explain the observed groundwater discharge on transient altitude zones. a possible reason may arise the decreasing infiltration due to continuously developing wastewater sanitation system, however its effect should be more significant in a longer time period. not surprisingly, due to the foregoing, extreme steep, a decisively downward trend can be experienced on the hydrographs along the river tisza. locally such steep downor upward trends can be experienced often, that hydrographs of the neighboring gauges absolutely do not confirm. these are probably consequences of a specific anthropogenic effect (like, exploitation of irrigation water from groundwater due to serious drought), long-lasting floods or inland excess water. in the next step we analyzed average water level changes of the hydrographs from 2005 to 2015. gauges located close to the tisza river show the highest fluctuation within a year (fig. 7.). on the alluvial fan of the maros river slightly smaller, on the central area of the sand ridge some minimal water fluctuation can be detemined. note, that these values are averaged to the whole analyzed 10 years (fig. 4 d, e, f), however interannual values significantly diverge from the multiannual average. the average water fluctuation range in the observed area mostly can be determined within a 10 cm confidence interval, however the highest and lowest uncertainties were also observed along the tisza river. note that the lowest uncertainty area around szeged (a city lying in the southern central area) are probably affected by the effects of the urban area. the average date of the highest groundwater level is also determined in the 10-year long time series. as awaited, this pike value can be expected in most cases in march and april (fig. 8.), however it can be determined with high uncertainty (with 30-60 day wide confidence interval). at multiple locations significantly different pike time moments can be experienced. this may refer to water inundation. our analysis indicated that the least groundwater was stored on 12/10/2009, and the most was available on 24/03/2011 (fig. 5). accordingly, the water resource fig. 6 average annual change of groundwater in cm (a) and probability of the groundwater discharge over the 2005-2015 period (b) fig. 7 estimated groundwater fluctuation range averaged over 2005-2015 (a) and the estimation uncertainty expressed in cm (b) 50 fehér (2015) shows cca. 5.5 km3 fluctuation (discharge) in one and a half years. the groundwater level map of these two moments is illustrated in fig. 9. extremely low groundwater level can be seen in 2009 on the western site, whose spatial pattern draws well the sand ridge. in contrast, the highest water level can be seen not along the tisza river, as it was expected, but half way between the sand ridge and the river. this has two possible reasons: (1) the river plays a role as a “drainage channel”, thereby tapping the water resources from its neighborhood, and (2) the water resources are significantly replenished by gravitational flow from the sand ridge even in drought periods. the relatively higher water levels of the eastern part of the study site can be considered similarly as a result of uplifting underground flows through former water beds. the situation in 2011 is at least as interesting as the above explained. on the area of the sand ridge some 2-3meter-deep water levels evolved, which means 2-meter recharge there. however, from agricultural perspective a very harmful situation occurred. on most of the site, the water depth was shallower than 1 meter, and in worst cases it inundated the surface. for example, in the eastern zone of the sand ridge, the subsurface water flow from the higher areas elevated the groundwater level insomuch that it caused floodings on the ground. the pattern of the groundwater on the former alluvial fan of the maros river quasi designate the former main river beds, probably attributable to the the permeable bed deposits. conclusion the methodology originally proposed by kyriakidis and journel (2001) has been improved to the stochastic analysis of non-complete, daily observed groundwater levels on a south-eastern hungarian site. groundwater hydrographs are considered spatially correlated due to the similar long-range background processes. the well-informed time domain was capitalized to improve reliability of a spatiotemporal estimation. the simulated hydrographs provide a probabilistic framework to estimate and evaluate both temporal and spatial patterns, furthermore, changes of fig. 8 estimated date of the pike groundwater level averaged over 2005-2015 (a) and the estimation uncertainty expressed in days (b) fig. 9 stochastic evaluation of 125 joint spatio-temporal stochastic simulation. e-type estimation of the groundwater depth in 12/10/2009 (a), in 24/03/2011 (b) and the probability of the groundwater deeper than 2 meters in the similar time instants (c and d respectively) a spatiotemporal stochastic framework of groundwater fluctuation analysis … 51 available water resources on the site alongside the spacetime uncertainty of the estimations. the methodology can be well supplied to determine spatial and temporal patterns of the groundwater resources. after the 1970s in hungary, a serious groundwater discharge had occurred on the sand ridge, between the river danube and the tisza. in some particular sites this depletion seems irreversible. the main causes are attributed to water extraction and the increasing area of forests. nevertheless, our study shows that in a decisive part of the area, besides groundwater depletionc the meteorological (and climatic) changes can be identified. specifically, in the whole danube-tisza 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10.1515/jengeo-2015-0007 issn: 2060-467x simulating environmental impacts based on the example of roşia montană gábor barton scottish natural heritage, great glen house, leachkin road, iv3 8nw inverness, united kingdom e-mail: gabor.barton@snh.gov.uk research article, received 6 june 2015, accepted 25 july 2015 abstract one of the challenges of modern terrain modelling methods is to incorporate non-existing, planned features in the output. remote sensing based solutions can only detect structures and shapes that are already present in the environment. in order to assess the impacts of a planned development on the surrounding landscape properly it is inevitable to solve this issue. in addition to the environmental, social and economic consequences, mining activities, especially open cast mining will also leave significant scars on the landscape. these can not only have a visual effect but also impact local weather conditions by changing winds, precipitation patterns. the current paper demonstrates a collection of methods and techniques able to cope with the various challenges that arise when modelling the landscape impacts of such developments. the experiments were performed in the area of roşia montană, where a canadian company plans to create the largest open cast gold mine in europe. the results of the terrain modelling process allow for the quantification of the estimated impacts on the terrain and the land cover of the area caused by the mining project. the presented methodology and visualisation tools can also facilitate the decision support mechanisms making the communication ‘more understandable’ amongst stakeholders; information meetings and public hearings involving organizing groups at any level. obtaining the results required the development of several unconventional techniques especially in terrain modelling and visual landscape simulation, involving the combination of sometimes very different base methods. keywords: digital terrain modelling, visual impact assessment, landscape modelling, decision support, roşia montană introduction spatial decision support systems (sdss) contain different components and can be used for planning, management and public communication purposes. integrated structures of spatial data, numerical models and formulated expert knowledge are widely applied in environmental studies since computing, geodata collecting and processing technologies, such as database management tools, geographic information system (gis) and remote sensing (rs), are available for researchers, analysts and policy makers (goodchild et al., 1996; bareth, 2009; laudien et al., 2010). the growing official and public demand of access to modern, realistic and user-friendly computer visualisation technologies suggests the new potentials of geovisualization and navigable virtual landscape in decision and policy support and public relation, beyond digital cartography (sheppard and cizek, 2009; pettit et al., 2011). the development of sdss requires a harmonized dataset of spatial information. however, the necessary sources are not always available. difficulties and elaborated solutions are also presented in the paper, in the case of the planned environmental intervention of the largest open cast gold mine in europe. roşia montană (verespatak, goldbach) and the surrounding region is known for its extensive resources of gold, silver and other minerals. the town has rich mining traditions dating back more than 2000 years (téglás, 1888; sîntimbrean and bedelean, 2002; géczi and bódis, 2003; paşca, 2010). the most significant remnants of the mining activities is the extensive network of shafts and tunnels built in the roman era, some of which are open for visitors in the mining museum. the activities have been present almost constantly until 1996 when the romanian state mining company decided to stop the extraction due to unsatisfactory yields (géczi, 2011). canadian company gabriel resources formed a new business called roşia montană gold corporation (rmgc) in 1999, which planned to create the largest open, cast gold and silver mine in europe. their estimates say that 300 metric tons of gold and 1600 metric tons of silver can be extracted in a period of 20 years (haiduc, 2003; géczi et al., 2005; paşca, 2010; rmgc, 2015). the project has raised vocal opposition from civil organisations (buzoianu and țoc, 2013; mti, 2013) because of the environmental risks posed by the cyanidebased technology that is planned to be used for ore processing (földessy and bőhm, 2012; parasca and butnaru, 2014). this will require the creation of a 2.7 km long tailings reservoir, covering 304 hectares while flooding a village. the pond will be held in place by a 180-metre-high dam (bara, 2002, haiduc, 2003). in spite of the company’s plans to start the project in 2006, the impacts of the tisza cyanide pollution in 2000 (prommer and skwarek, 2001; wwf, 2002) and mailto:gabor.barton@snh.gov.uk 2 barton (2015) the breach of the alumina tailings dam near kolontár in 2010 2010 (bbc, 2010, icpdr, 2011) among other similar environmental disasters succeeded in thwarting the commencement of mining activities thus far. the controversy surrounding the project does not stop at potential environmental risks though. according to the yield-estimates performed on behalf of rmgc, the actual gold and silver content of the rocks is so low that it borders on being economically unviable to extract. this means that the amount of profits and subsequent taxes toward the romanian budget is highly unstable and difficult to estimate with high accuracy, especially when the fluctuation of gold prices is also taken into account. the low grade of ore content also requires enormous amounts of rocks to be processed and results in a very large volume of unusable waste material, some of which will be deliberately contaminated with cyanide and other dangerous chemicals (haiduc, 2003). the subsequent storage, management and maintenance of these materials will invoke further costs as well as environmental risks for several years after the project is deemed complete. the objective of the current study is to estimate the environmental impacts of the project as proposed by rmgc. the research focus is the terrain and the visual impacts on the landscape, as well as determining the changes in land cover. i will also demonstrate the results of a simulation about a dam failure on the planned tailings reservoir. study area roşia montană is located in the nw part of alba county in romania. the actual township is made up of several smaller settlements in the roşia valley with the centre being in the top half of the valley (fig. 1). the population of the settlement cluster was 2656 in 2013, according to the romanian office of statistics. the largest settlement in the study area is abrud, in the sw corner with 5072 inhabitants in 2013. fig. 1 location of the study area the concession zone is about 24 square kilometres, but for better context the full study area contains a 10 by 10 kilometre square. in terms of hydrology, the main watercourse in the study area is the river abrud flowing to the north into river arieş, a tributary of river mureş (maros) which in the end flows into river tisza near szeged, hungary. since the main economic activity in the area is mining and associated processing industries, the waters have been heavily polluted, most significantly in the communist era, when little (if any) attention was paid toward the environment. the roşia stream still contains relatively high levels of heavy metals and other pollutants, although the concentrations are decreasing since the cessation of active mining and processing activities. the project plan proposed by rmgc inten ds to spend a considerable effort on improving the existing pollution sources as well as preventing future contaminations by diverting the natural water flows in the area. they also promise to respect the historical treasures of the area by avoiding the de signated protection zones. nevertheless, it is difficult to imagine that the high capacity vehicles, trucks and the explosions used in blasting out the mining pits will leave the surrounding buildings and historical landmarks unscathed. the biggest environmental risk of the planned project would be the tailings reservoir located in the corna valley (géczi et al., 2006). this pond, in its final stage will be filled with 213 million m3-s of waste material left behind from the ore processing. the sludge will contain high concentrations of cyanide and other harmful or toxic compounds (haiduc, 2003). by comparison, the tisza cyanide disaster in 2000 was caused by “only” 100,000 m3 of water containing cyanide and heavy metals. another significant risk factor is the location of the tailings pond, being just 1.78 km-s from the town of abrud. methods in order to perform the necessary modelling and simulation tasks extensive preparations had to be done as well. these involved obtaining the source data and maps from various sources and collating them into a common database. the majority of the process used various gis techniques, some of which have been developed and enhanced by the author. the most difficult challenge was to incorporate the planned mining facilities and landforms into the existing surface in a seamless way. artificial terrain elements tend to be more angular and to consist of more straight edges than those found in undisturb ed areas. the main task was to resolve this conflict in a combined elevation model. to this end, it was decided to take advantage of the best characteristics of the two major surface modelling methodologies: vector and raster based algorithms. simulating environmental impacts based on the example of roşia montană 3 both approaches are using points of fixed elevation as base, but they estimate the elevation of inbetween locations in different ways. the tin (triangulated irregular network) method in the first group generates triangles among the points with known elevation (peucker et al., 1979; esri, 1994). this results in a surface with an angular, edgy appearance. one of the advantages of the tin method is that it is computationally cheap, compared to the raster methods, delivering quicker results. however, the generated surface is visually quite different from the appearance of the most natural terrains, usually having much less edges and sharp breaks in them. the majority of natural terrains can be modelled better using a raster approach. while there are many mathematical models to interpolate the unknown elevation value of the points based on the input data, most of these are aimed to generate statistical surfaces. terrains have very specific features and characteristics, most of them formed by flowing water, which are beyond the capabilities of the generic interpolation methods like idw (inverse distance weighting), kriging or spline based solutions. a more advanced algorithm was developed at the australian national university (hutchinson, 1988) which was able to respect the special requirements set by the effects of natural processes on the surface. the anudem algorithm is now being used in esri’s arcgis spatial analyst behind the ‘topo to raster’ geoprocessing tool (hutchinson and dowling, 1991; hutchinson, 1996; hutchinson, 1997). the tool is able to take advantage of the input data types commonly used to describe terrains, such as contour lines, elevation points. water is the primary erosive force determining the general shape of most landscapes. for this reason, most landscapes have many hilltops (local maximums) and few sinks (local minimums), resulting in a connected drainage pattern. ‘topo to raster’ uses this knowledge of surfaces and imposes constraints on the interpolation process that results in a connected drainage structure and correct representation of ridges and streams. using any of the two approaches above on their own would still not be able to produce an output surface that is sufficiently “smoothed” in the undisturbed areas while keeping the angular quality of the artificial structures. to achieve this, a combination of techniques had to be used. this means that a base surface was created using ‘topo to raster’, and the rasterised tin models of the artificial structures were merged into it later using raster arithmetics. in the present study, the elevation data was based on the eu-dem database available as a free download from the european environment agency (eea) website. this was created using the latest versions of the aster-gdem and srtm (shuttle radar topography mission) surface models (hensley et al., 2000; hennig et al., 2001; farr et al., 2007) with additional edits to improve the water surfaces. the final model is a 30-metre-resolution, medium scale raster surface, which is very usable for researches based on watershed basins (tøttrup, 2014). the special requirements set by the modelling of artificial features required further processing of the raw eu-dem data in order to improve its resolution and hydrological accuracy. contours were derived from the surface at 10-metre intervals to serve as the base input for the new elevation model, which would be capable of storing the planned features as well. for better hydrological accuracy we used the water network layer in the romanian national cadastre agency’s inspire view service (ancpi, 2014), which was digitised manually for the extent of the study area. since ‘topo to raster’ is using the stream network to build valleys and ridges into the resulting surface, the existing streams and rivers had to be extended upstream, until the shape of the contour lines made it necessary. this ensured that the valley’s baseline was without obstructions and the water could flow freely as close to the natural conditions as possible. in the paper, this will be referred t o as refined eu-dem. rmgc has published its environmental impact assessment (eia) reports as pdf documents in several versions. for this study the 2006 version was used (rmgc, 2015), which contained detailed maps of the planned mining facilities and other structures in the following time series:  initial stage (year 0);  operational stage (year 7);  operational stage (year 14);  operational stage (year 16);  reclamation stage (year 19). the pdf documents were converted into gis compatible format and georeferenced into utm34n projection to match the rest of the input datasets. the planned shapes were grouped into two categories, each requiring its own approach in modelling. one group contained the planned quarries, mining pits and waste dumps. the most important part of modelling these structures was the creation of 3d line elements around them to define the boundary of the shapes. these 3d lines received their elevation values from the unaltered terrain (refined eu-dem), while being digitised to follow the edges of the mining structure. the planned structures also contained flat surfaces, which were modelled as simple polygon features with the elevation value read from the map labels stored as an attribute. in order to improve the accuracy of the tin surface some additional contour lines and 3d lines were required in places where the algorithm would have otherwise produced incorrect results. the digitised lines and polygons were then used to create tin surfaces. to ensure that the resulting surface only covers the area of the artificial features, a boundary polygon was also added as the input data. this tin model was then ready to be converted into a raster surface and to be mosaicked into the base refined eu-dem. the 3d lines around them ensured the seamless integration, with the boundary polygon made sure that triangles were only formed within the structure. 4 barton (2015) fig. 2 tin components of mining related features the other main group consisted of the lakes and reservoirs planned in the project. these were digitised as polygon features, but it turned out that additional concerns had to be taken into account. the maps in the eia were based on a terrain of unknown origins, as the map did not contain any information about the source of the used data. therefore, it was possible (quite likely) that the refined eu-dem would not match exactly to the shapes in the map which were based on a different elevation model. to overcome this problem the polygons representing the water (and similar) surfaces were digitised extending beyond the shapes in the map. the tin surface generated from the extended polygons was then converted into a raster surface based on the cell configuration of the base dem (refined eudem). the raster surface in its original state extended “below” the cells of the original dem, i.e. where it was higher than the level of the tailings pond or lake. these cells had to be eliminated before mosaicking using simple raster comparison and arithmetic operations. the same approach was used in the case of modelling the dam structures as shown in fig. 3. once the raster model only contained the cell that were higher than or equal to the corresponding cells in the original terrain, it could be merged into the surface. using this method ensured that no gaps are formed and the “water” completely fills up the available space in the model. taking the polygon digitised directly from the rmgc map may have caused such gaps, but this way the integration was seamless. fig. 3 determining the cells to be discarded based on their elevation values the modelling steps described above were performed for each of the project stages mapped in the eia report, so in the end, five simulated terrains were created. fig. 4 shows one of the maps draped on the built surface. an additional, but very important part of the process was to simulate impact of the planned changes on the visual appearance of the landscape. this involved modifying spot satellite images of the area using standard graphics editing tools. the modifications were performed in the gimp open source graphics software capable of every bit of functionality required in the editing. the baseline spot image was captured in 2006, showing the existing cetate mining pit and the surrounding area. using texture and colour samples taken from fig. 4 rmgc map of year 14 draped over simulated terrain model simulating environmental impacts based on the example of roşia montană 5 existing tailings ponds, mining pits, quarries and other features in the surrounding region (most notably the copper mine near roşia poieni) it was possible to generate hypothetical images of the planned changes. textures could be obtained from other sources as well, for example, fig. 5 shows the tailings pond in year 7 of the project, with the dam’s texture copied from the photo in the bottom right corner. creating the visual appearance of roads was done by using the simple paintbrush tools and taking a colour similar to that found on the majority of existing roads in the image. the modifications were then subjected to various colouring and artistic effects to increase the level of similarity to the original satellite image. as with the terrains, the satellite images were also produced in five versions, which were later used in animations and timeseries composite images. results the simulated terrain models are shown in fig 6. another aspect of the results was the estimation of land cover changes in the area. based on the simulated spot satellite images and the original corine (eea 2000) land cover 2006 (clc2006) map of the study area it was possible to create a time series of the planned changes. the process involved removing any clc2006 polygons from within the affected areas and repopulating these blanks with new polygons according to the modified spot image data. analysing the relationship between current conditions on spot and clc2006 it was quite possible to determine the changed land cover category. the simulated land cover of the reclaimed waste dumps takes into account the passage of time as well. this means that in project years 14 and 16 they are classified as scrub, while in year 20 they change into mixed forest, assuming the areas would be planted with fast growing trees. the time series maps of the simulated clc data are shown in fig. 7. using the source clc2006 data and the boundary polygon encompassing all the planned mining features it was also possible to calculate the ratio of land cover types that will be impacted by the project. the boundary polygon was created by merging all the clipping polygons used in the tin generation stage. table 1 shows the results of this analysis. the percentage should be interpreted as the ratio of the land cover class within the area affected by mining. table 1 distribution of different land cover types based on the corine land cover data for the year 2006 clc2006 code land cover class area (%) area (ha) 311 broad-leaved forest 40.56 379.22 231 pasture 25.87 241.87 131 mineral extraction site 11.54 107.92 112 discontinuous urban fabric 9.91 92.63 242 complex cultivation pattern 8.72 81.48 313 mixed forest 2.89 27.02 324 transitional forest-shrub 0.51 4.74 total 100 934.88 fig.5 simulated spot image of year 7 (photo in bottom right contains the texture sample for the tailings dam) 6 barton (2015) fig. 6 time-series maps of the simulated terrain changes fig. 7 results of simulated clc maps for each mapped project stage simulating environmental impacts based on the example of roşia montană 7 one of the derivatives of the generated terrains was a time-series with the changes in elevation values during the project, shown in fig. 8. fig. 8 elevation changes in the study area the generated terrain models allowed for the calculation of the volume of the relocated materials between each stage. the resulting figures are only estimates; their accuracy depended on the spatial resolution of the input surface models (20 metres) and the accuracy of the baseline, refined eu-dem data. one additional issue regarding the volume changes was that one of the four main mining pits (called jig) did not appear in the rmgc maps in its excavated state. the plan for year 7 showed nothing in its area, while the one for year 14 showed that the pit has already been completely filled back with material. this meant that the volume of rock moved from and to jig was left unknown. table 2 lists the calculated amounts, with the limitations described above. the calculations reveal that 529 million cubic metres of rocks and other materials are going to be relocated during the 16 years of active mining. the rmgc map after year 16 showed no changes in the terrain, mostly because the focus during those years is on reclamation of the disturbed areas. the two pit lakes in the cetate pit and the extraction surfaces in neighbouring carnic and orlea pits will remain untreated as mining exhibits. the tailings pond is planned to be reclaimed as low value grazing land or managed grassland. the toxic compounds within the tailings material will require several decades to decompose properly into less dangerous chemicals, but the topsoil would be transported from stockpiles collected from other areas beforehand. the relocated materials were also visualised in a series of maps. the blue areas are those where material has been removed, the red patches cover the areas where material has been deposited (fig. 9). table 2 results of volume change calculations for each stage and the full project duration (thousand cubic metres) mining feature present – yr. 0 year 0 – 7 year 7 – 14 year 14 – 16 total dump north of tailings pond 2,216.80 0 0 0 2,216.80 sandstone quarry -1,256.82 0 0 0 1,256.82 andesite quarry -3,313.85 0 0 0 3,313.85 andesite quarry waste dump 1,334.66 0 0 0 1,334.66 topsoil pile south of tailings dam 1,005.98 0 0 0 1,005.98 carnic waste dump 1,029.49 45,551.14 14,778.60 0 61,359.23 carnic pit -127.53 -71,514.01 -47,862.92 -91.77 -119,596.23 cetate pit 0 -23,955.94 -45,190.33 0 -69,146.27 cetate waste dump 2,420.90 26,951.20 0 -297.72 29,074.38 orlea pit 0 -274.69 -18,482.88 0 -18,757.57 cetate lakes (water) 0 0 0 9,193.02 9,193.02 tailings reservoir 20,549.74 59,741.77 81,059.31 52,385.16 213,735.98 total volume of relocated material (absolute value) 529,990.79 8 barton (2015) discussion and conclusions environmental or infrastructural investments triggering significant changes require comprehensive impact assessment. spatial decision support systems include tools enabling the creation of alternative scenarios. they also offer access to visual information and visual analytics functionality. these capabilities made such systems widely applied and an essential part of analyses of possible future geo-scenarios (sheppard and cizek, 2009; pettit et al., 2011; sheppard, 2012). the nimby syndrome (“not in my backyard” attitude expressing low public acceptance or opposition by residents to new proposals) is a frequently experienced situation (wolsink, 2007). landscape modelling extended by advanced visualisation methods for communication of landscape futures scenarios to stakeholders can enlighten hidden aspects of projects facilitating better understanding of pros and cons (pettit et al., 2011). the analyses performed on the simulated terrain data covering the area of the largest open ca st gold mine in europe have also revealed several results unforeseen without the presented unconventional, combined environmental and digital elevation modelling techniques (barton et al., 2015). some of these offer deeper insight into information already known from the rmgc eia reports and studies (haiduc, 2003; paşca, 2010; rmgc, 2015), but some shed light on previously unknown consequences or details. the terrain modelling processes developed during the research offer much more usable surfaces by combining the best characteristics of raster and vector methods, as the planned surface requires them. they allow the analyst to simulate terrain changes based on nothing more than the maps of the planned developments. the visual impact simulation process (performed by editing satellite images using standard graphics software) offers an inexpensive, efficient and creative way to visualise the changes in the landscape. the resulting terrain and image data can be displayed in 3d images and animations for better exp laining the results to the community. area and volume calculations show that approximately 0.5 cubic kilometres of rock and other materials would be relocated during the planned mining project. when this amount is compared to the 300 metric tons of gold and 1600 tons of silver rmgc is expecting to extract we can see how disproportionate it is. the relatively low grade of the deposits in the area results in a very large impacted zone (934 hectares), 1/3 of which is taken up by the tailings pond in corna valley. this will contain more than 200 million cubic metres of waste materi fig. 9 areas of material relocation during the stages of the project simulating environmental impacts based on the example of roşia montană 9 al left behind from the cyanide leeching processes and will require close monitoring and management for several years after the project is closed. the toxic compounds will make any meaningful land use very difficult in the future while it poses a potential threat to both the environment and the health and safety of the population downstream. having a 180-metre high dam just 1700 metres from a town of 5000 people (géczi et al., 2005), which is holding back thousands of tons of toxic sludge can easily be called irresponsible. unless all the safety and building material requirements are strictly enforced, the dam will be liable to failure and this disaster would certainly have a severe impact on the river maros. the river flows through densely populated regions of central western romania, much of which relies on the river for irrigation and drinking water. since there are already numerous mining operations in the region acting as additional pollution sources, it is very difficult to rationalise the introduction of such a high risk factor into the system. thinking back on ecological and subsequent economic consequences of the tisza cyanide disaster in 2000 (caused by a fraction of tailings material than what is planned in roşia montană) it is easy to imagine how severe an impact a dam breach would cause. the modelling shows that the project would irrevocably turn the area into a highly industrial landscape. while it is true (if the company can live up to its word) that many of the currently observable pollution sources would be eliminated, we cannot forget about the new potential risks that would be introduced, especially the tailings reservoir. it is also very flexible whether the company can actually offer the amount of employment opportunities it is advocating in it campaign for the mine. moreover, this amount will inevitably decrease with time as new and more efficient technologies are constantly being developed. acknowledgements i would like to express my thanks to dr. róbert géczi, for giving me insight into the mining history and the environmental values of roşia montană. his information was very useful and made me aware of the possible environmental, economic and social changes. he also confirmed my belief that evaluating the impacts of the planned project (and other similar initiatives) will provide interesting challenges to the gis and the research community in the future. i also wish to thank dr. katalin bódis for her invaluable advice in methodology and research questions. references ancpi 2014, agenţia naţională de cadastru şi publicitate imobiliară, inspire hy view service – http://geoportal.ancpi.ro/arcgis/rest/services/hy [accessed november 2014] bara, a. 2002. rosia montana gold mine: a future predictable catastrophe. cee bankwatch network, cee bankwatch network. online: http://bankwatch.org/documents/rosiamontana.pdf 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(2001), and liu et al. (2010) were also using vector quantization for the mapping of fungal plant infections. the scope of environmental applications includes floodplains and saline soils (burai andtomor, 2011; kardeván et al., 2003), laboratory measurements for the estimation of various biochemical parameters (lausch et al., 2016) and the monitoring of plant diseases (liu et al., 2010; visi-rajczi et al., 2012). in our study we focused on some basic statistical approaches to estimate the separability and the classification accuracy of crops based on hyperspectral aerial photography. conclusions derived from our results can be used for the improvement of field surveys, feature and noise reduction and the preliminary planning of aerial photography campaigns. background the so called curse of dimensionality is a significant obstacle to hyperspectral data interpretation, the large number of data bands combined with data noise and limited training areas can lead to poorer classification accuracy (landgrebe, 2003). a possible way to mitigate this risk is either to improve the ground truth data set or to perform feature reduction (i. e. principal component transformation). in order to test the training pixels we can calculate spectral separability indices that indicate the overlappings between classes. both jeffries-matusita and transformed divergence algorithms were proven to be efficient tools for the evaluation of vegetation, soil and other land cover training sites (büttner et al., 1988; metternicht and zinck, 1998; ustin et al., 2009). 50 csendes and mucsi (2016) another way to present spectral similarities is to plot image data to a 2 dimensional feature space where pixels are usually arranged in a triangle of soils, water surfaces and vegetation (tobak et al., 2012). the elaboration of ground survey is crucial for the agricultural applications of remote sensing, some studies show that adding biochemical and soil parameters increases mapping accuracy on high resolution imagery (burai, 2006). hence, the limitation of ground truth data is a serious constrain for the classifications which can be mitigated using non-parametric methods that are less sensitive to small deviations, like the sam (burai et al., 2010). study area the geographical region of our study, the flood plain area called tápai-rét is situated in southeastern hungary, at the outskirts of the city of szeged, over the confluence of rivers tisza and maros (fig. 1). the landscape is mainly characterized by cultivated agricultural land and parcels of various sizes and settlements of scattered farmsteads. due to its small differences of elevation and the remarkable diversity of crops tápai-rét is an ideal site to examine spectral discrimination techniques. fig. 1 the geographical location of the study area land use in hungary is usually dominated by smaller agricultural parcels and it is also true for the tápai-rét area where a great part of the territory belongs to the irregular network of farm. the mosaic of small and diverse parcels imposes an obstacle to field surveys and significantly limits the number of available training points for the crops. data and methods hyperspectral imagery were acquired in september 2010 using the airborne spectrometer of aisa. reflectance values were recorded on 359 spectral bands between the wavelength of 0.4 and 2.4 micrometers with a spatial resolution of 1.5 metres. some of the bands contained significant amount of noise, the values for these wavelength regions were left blank on the reflectance curve diagram (fig. 2). around 120 spectral bands were removed based on their spatial autocorrelation values, however, we kept all the data from the region between 400 and 900 nanometers as these reflectance values are the most informative about vegetation characteristics. fig. 2 average spectra of the four crop species we used online cadastral maps (fig. 3) and the expertise of local farmers to collect ground truth data about the crops. the online map contains the 5 digit id numbers for each parcel that are connected to the ownership information, the database is managed and regularly updated by the hungarian cadastral office. fig.3 the online cadastrial map of the study area identification and spectral evaluation of agricultural crops on hyperspectral airborne data 51 an accurate method to verify the selection of training points is the calculation of spectral separability. formulas like the jeffries-matusita or the transformed divergence distance show index values on a scale of 0 to 2 where 0 refers to complete overlapping and 2 indicates perfect separability. these calculations are based on the comparison of reflectance or other data values within a certain range. however, it is essential to have more training points than the dimensionality, or in other words, the number of the spectral bands. in order to meet this criteria, feature reduction of the hyperspectral imagery is required if the set of data samples cannot be extended. for this purpose, in our study we performed a principal component transformation, where the first few transformed data bands contain most of the spectral information with a reduced degree of noise. another important aspect of the training site selection is the spectral homogeneity of the pixels. it can be affected by some possible spatial autocorrelation, the presence of noise, and also the heterogeneity of the examined land cover features. we selected spatially diverse training areas for the better characterization of our classes and to avoid the use of pixels with similar traces of noise. standard deviation was calculated for single spectral bands both from the visible (550 nm) and the near-infrared region (900 nm). the spectral angle mapper (sam) algorithm was applied for the classification which is considered as a relatively simple spectral statistical method as it calculates only the average of the sample spectra and the vector angle deviations of the individual test points, measured by the milliradian. our goal was to compare the results of this non-parametric classifier with the values obtained from the training site image statistics. results spectral separability measurements to examine the possible spectral overlappings between the classes we performed spectral separability measurements. jeffries-matusita (jm) and transformed divergence (td) indices have proven to be powerful tools for the evaluation of training areas (metternicht and zinck, 1998; ustin et al., 2009; tobak et al., 2013). since these calculations require more spectral samples than the number of the in put bands, we used a principal component transformation to reduce data dimensionality. separability values were measured on the first two pc bands for the four crop classes (table 1). the td index happened to be less sensitive to the overlappings than the jm, however, the results are in agreement as the ranking of the classes is the same, medick is completely separable from the rest of the species, while a high extent of spectral similarity occurs between the pixels of the other 3 class es, especially in the case of those of garlic and sugar beet. table 1 jeffries-matusita (jm) and transformed divergence (td) indices based on the values of the first two principal component bands medick corn garlic sugar beet td medick 0 2 2 2 medick corn 2 0 1.08 0.58 corn garlic 2 0.78 0 0.27 garlic sugar beet 2 0.53 0.26 0 sugar beet jm medick corn garlic sugar beet scatter plot visualization spectral classes can be visualized by plotting the pixel values of certain image bands, in our study we used the first two principal component bands to illustrate the relative positions of the pixel groups in the spectral space and indicated denser areas with lighter colour shades (fig. 4). the elements of 2 dimensional plots usually form the shape of a triangle when studying imagery of a natural landscape where the three endmembers are vegetation, water and soil surfaces (mucsi and henits, 2011; tobak et al., 2012). the scatter plot of our study area has the pixels of medick in the upper left corner, separated from the other crops which are closer to the brighter central region where most of the vegetation data points are located, thus confirming the findings of the separability measurements. in comparison, grassland pixels from the external regions of the original aerial photography can be found scattered below the main line of vegetation, water and some shaded surfaces are situated in the upper right corner of the triangle, while soils and concrete are in the bottom (fig. 4). fig.4 crops featured on the scatter plot of the first two2 pc bands 52 csendes and mucsi (2016) homogeneity analysis the outcome of the supervised classification is affected by the homogeneity of the training areas, therefore we analysed the standard deviation of reflectance values per single spectral bands (table 2), where data from the visible range (550 nanometres), from the near infrared (900 nm), and one band from the short-wavelength infrared (swir) region (2100 nm) were used. reflectance values were found more homogeneous in the visible and in the swir wavelength regions, while there is a significant increase of the standard deviation at the near infrared light range that can be explained with the individual characteristics of the plants’ spectral red edge. corn shows relatively low heterogeneity compared to the other three species, however, these values depend not only from the spectral features of the vegetation, but also from the spatial distribution and the noise content of pixels. table 2 standard deviation of reflectance values per single bands wavelength medick corn garlic sugar beet 550 nm 0.0090 0.0031 0.0067 0.0037 900 nm 0.0394 0.0235 0.0357 0.0337 2100 nm 0.0068 0.0041 0.0068 0.0062 sam classification the sam classification was performed without any spectral angle threshold specified to have more information on misclassifications between our crop classes. table 3 shows the confusion matrix of the result, where columns represent the ground truth points (15 items per class) and rows display the classified pixels. the two approaches of classification accuracy measurement (users’ and producer’s accuracy) show more or less the same results on the reliability of identification. the overall accuracy of the mapping is on an acceptable level (72%), however, significant differences can be observed between the results of certain classes. the worst performance was in the category of sugar beet, where the slight majority of control pixels where misclassified. also, the highest extent of confusion was registered between sugar beet and garlic. figure 5 presents the spatial distribution of the 4 classes on the true colour hyperspectral image. as it can be seen on the picture, the mapping categories of the crops rarely extend beyond the parcels, the sam classification rather omitted to detect certain pixels of agricultural vegetation. the parcels of corn and medick are easily recognizable, their mapping classes designate more or less homogenous bocks. on the other hand, in the case of the two western parcels there is a high level of misclassification, especially between the categories sugar beet, garlic, and corn, as it was predicted by the separability measurements. table 3 confusion matrix of the sam classification, indicating users’ accuracy (u. a.) and producer’s accuracy (p. a.) medick corn garlic sugar beet u. a. medick 15 100% corn 12 1 3 75% garlic 9 5 64% sugar beet 3 5 7 47% p. a. 100% 80% 60% 47% 72% fig. 5 the four sam classes placed over the true colour image of the hyperspectral data: sugar beet (blue), garlic (red), corn (green), and medick (purple) discussion sam classifier was proven to be an accurate technique for the spectral discrimination of most of the crop species, however, in the cases of spectrally less separable plants (sugar beet and garlic) classification results were significantly poorer. the calculation of spectral angles has also the advantage that the outcome of the analysis is insensitive to the level of illumination of the surface objects, thus shaded pixels will have a lower rate of misclassification (van der meer, 2004; lillesand et al., 2004; kruse et al., 1993). some papers also suggest that sam provides acceptable results on hyperspectral data when the number of training points is significantly limited (burai et al., 2010; tobak et al., 2012), although an increasing number of authors prefers machine learning algorithms for advanced classifications and land cover mapping (huang et al., 2002; lary et al., 2015). our finding, that the jeffries-matusita distance is more sensitive to spectral similarities than transformed divergence has confirmed the same conclusions of jensen 1986. in his study burai (2006) examined the spectral features of similar plants (medick, corn, sugar beet, etc.) in a much larger study area, obtaining an overall mapping accuracy of 85,5%. he argued that the use of an extended and more detailed ground truth database including soil parameters can significantly improve the reliability of classifications, which is in line with our conclusions. identification and spectral evaluation of agricultural crops on hyperspectral airborne data 53 conclusion our main goal was to compare classification results with some spectral statistical analyses we performed on the pc transformed data and on single spectral bands. using spectral separability measurements we found two classes that show significant overlapping (sugar beet and garlic) what was also confirmed by the sam accuracy results. also, it was proven that spectral separability distances correlate with classification results, where a higher degree of spectral overlapping on the pc transformed data can lead to poorer accuracy even in the case of a high resolution hyperspectral dataset. we also examined the spectral homogeneity of training points and we concluded that the standard deviation values of the classes do not show a strong correlation with the classification’s outcome. as the sam results resembled those of the separability distance calculations, we drew the conclusions that despite the possible data loss, principal component transformation is an applicable tool for the identification and comparison of crops on high resolution imagery even when spectral differences are very subtle and the size of training areas is limited. acknowledgement this research was supported by the european union and the state of hungary, co-financed by the european social fund in the framework of támop 4.2.4. a/2-11-1-20120001 ‘national excellence program’. references burai, p. 2006. földhasználat-elemzés és növény-monitoring különböző adattartalmú és térbeli felbontású távérzékelt felvételek alapján (land use analysis and vegetation monitoring using remote sensed images of different data content and spatial resolution). agrártudományi közlemények 2006/22 különszám, 7–12. 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(in hungarian). tobak, z. 2013. urban surface analyses using high temporal and spectral resolution aerial imagery. phd theses, university of szeged, hungary. tobak, z., csendes, b., henits, l., van leeuwen, b., szatmári, j., mucsi, l. 2012. városi felszínek spektrális tulajdonságainak vizsgálata légifelvételek alapján (spectral analysis of urban surfaces using aerial photography) in: lóki, j. (ed) az elmélet és gyakorlat találkozása a térinformatikában iii, debrecen, 413-420. isbn:978963-318-218-5 (in hungarian:). ustin, l. s., valko, p. g., kefauver, s. c., santos, m. j., zimpfer, j. f., smith, s. d. 2009. remote sensing of biological soil crust under simulated climate change manipulations in the mojave desert. remote sensing of environment 113, 317–328. doi: 10.1016/j.rse.2008.09.013 visi-rajczi, e., burai, p., király, g., albert, l. 2012. ecological characterization of the green areas in sopron by plant chemical analysis and hyperspectral recording. in: the impact of urbanization, industrial and agricultural technologies on the natural environment: international scientific conference on sustainable development and ecological footprint. university of west hungary, sopron. isbn 978-963-334-047-9 introduction background study area data and methods results spectral separability measurements scatter plot visualization homogeneity analysis sam classification discussion conclusion acknowledgement references journal of environmental geography journal of environmental geography 8 (1–2), 39–47. doi: 10.1515/jengeo-2015-0005 issn: 2060-467x comparative grain-size measurements for validating sampling and pretreatment techniques in terms of solifluction landforms, southern carpathians, romania raul david serban 1* , györgy sipos 2 , mihaela popescu 1 , petru urdea 1 , alexandru onaca 1 , zsuzsanna ladányi 2 1 department of geography, west university of timisoara, v. parvan str. 4, ro-300223timisoara, romania 2 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: raul.serban88@e-uvt.ro research article, received 10 march 2015, accepted 15 june 2015 abstract grain-size distribution has become in the last years an important indicator in the analysis of periglacial processes and landforms. however, as they exhibit a complex sedimentology, careful sampling is required to draw meaningful conclusions. the aim of the present study was therefore to validate the sampling procedure carried out on solifluction forms and to evaluate the effect of sampling pretreatment during grain size analysis. a comparison between multiple measurements of grain size distribution using the laser diffraction method (ldm) was performed on 54 sediment samples collected from different solifluction landforms at different depths in the alpine area of the southern carpathians. the results of parallel measurements were compared using textural and statistical indicators. the received distributions reinforced the properness of field sampling procedure in most of the cases. the results of textural classification and fractional composition showed a high consistency between the two parallel measurements made on untreated and pretreated samples. an overall fining as a matter of etching was identified. relative deviation increased and correlation decreased as pretreatment advanced. hcl etching resulted a greater deviation and variability in case of the sand fraction, h2o2 rather affected the silt fraction. the greatest deviations were experienced in case of landforms developed on crystalline limestone. pretreatment of samples introduced a major uncertainty to further comparison and interpretation. thus, multiple ld measurements on a representative group of samples from the entire sample set were suggested before the geomorphological or environmental interpretation of results to decrease the uncertainties and to validate the processes. keywords: laser diffraction method, grain size distribution, acid pretreatment, solifluction landforms, southern carpathians introduction grain size distribution is one of the most important sedimentological parameters (ryżak and bieganowski, 2011), representing the percentage of the total dry weight of sediment grains of a given size fraction. grain size distribution influences other properties such as pore distribution, water retention, water conductivity, soil nitrification, thermal and absorption properties etc. (ryżak and bieganowski, 2011), which in turn highly influence alpine solifluctional processes and landforms. in the last years several new methods were developed for grain-size analysis, including electroresistance counting, photometrical techniques, x -ray attenuation, optical determination using image anal ysis, time of transition and laser diffraction (mccave and syvitski, 1991; beuselinck et al., 1998; goossens, 2008; di stefano et al., 2010). all these new methods generally have the advantage of covering a wide range of grain sizes, using less quantity of sediments, speed in analysis, reproducibility and fewer possibilities for operator failure (di stefano et al., 2010; kun et al., 2013). among these the use of the laser diffraction method (ldm) seems to be the most widespread, as it is cost effective, its precision and reproducibility are high. ldm is basically based on the dispersion and diffraction of a laser beam on the measured particles. the scattered laser light is recorded on sensors and the diffraction angle in which the beam is scattered is inversely proportional to particle size. the software of the equipment recalculates the information from the sensors into volumetric grain size distribution (ryżak and bieganowski, 2011). the accuracy of the measurement is influenced by many factors, e.g. the color of the suspension, the mi neral composition and opacity of particles, or by organic and carbonate content (kun et al., 2013). considering that grain size measurements are affected by the applied pretreatment method, there has been a debate on what procedures should be applied. some researchers still underline the necessity of using acids when the organic content is high (murray, 2002) while others found this unnecessary (beuselinck et al., 1998) and stating that ultrasonic dispersion can replace chemical pretreatment and dispersion methods (ryżak and bieganowski, 2011). 40 serban et al. (2015) in earth sciences ldm has mainly been applied on soil samples, loess, lacustrine, marine and, fluvial sediments (loizeau et al., 1994; konert and vandenberghe, 1997; buurman et al., 2001; arnaud, 2005; di stefano et al., 2010; ryżak and bieganowski, 2011; forde et al., 2012; kun et al., 2013), and just in the last years starte to be applied on solifluction landforms (ridefelt and boelhouwers, 2006; oliva et al., 2009; ridefelt et al., 2011). grain-size analysis carried out on solifluction landforms so far has beene made on untreated samples, without evaluating the necessity of pretreatment or the sampling strategy. applications in alpine environments require more attention regarding that the material from solifluction lobes is disordered and overlapped by slow mass soil moving (harris et al., 2008). in these circumstances representative and reproducible field sampling can be an important issue and must be validated before drawing further sedimentological or geomorphological conclusions. the aim of this study thereby was to attest the correctness of sampling in case of southern carpathian solifluction landforms using multiple laser diffraction measurements and to evaluate the effect of sample pretreatment on the results. study area and methods solifluction sediment samples were collected from the alpine area of southern carpathians, romania, from different mountain ranges (fig. 1). the southern ca rpathians are the highest sector of the romanian carpathians (moldoveanu peak – 2544 m a.s.l.) with seasonal freezing conditions in more than 6 months annually (urdea, 1993). in the alpine area the climatic conditions are rather cold, with negative mean annual air temperature above 2000 m a.s.l. (-0.5°c at ţarcu 2180 m a.s.l and -2.4°c at omu -2505 m a.s.l.) and precipitation over 1000 mm. above the tree line (1700-1800 m a.s.l.) extensive areas are affected by solifluction, whereas other periglacial landforms (block streams, rock glaciers, talus cones and scree slopes, block fields, patterned ground, ploughing blocks, earth hummocks, etc.) are also common. the southern carpathians are in general composed of crystalline schists with granite intrusions, especially in cindrel and făgăraș moutains. whereas the tarcu moutains is primarily built up of granitoides (northern part), limestones (central part) crystalline schists, sandstones and conglomerates. in terms of lithology, cindrel and sureanu moutains belong to the getic fabrics (paragneiss, micaschists and amphibolites), while parâng moutains are part of the danubian unit (granitoides, amphibolites, and limestones). characteristic soil type in the area is alpine meadow umbrisol, from the typical to cambic, lithic and skeletal subtypes. a wide variety of solifluction landforms occur in the alpine environments based on their genesis. most common and widespread are turf-banked solifluction lobes, while so called ploughing blocks are less frequent (fig. 2). the term solifluction include all the processes (gelifluction, frost creep, frost heaving and frost sorting, periglacial elevation) contributing to slow mass soil movement in a periglacial environment and leading to the formation of solifluction lobes and terraces (harris, 2007). solifluction lobes have a frontal height ranging from several cm to more than 1 m and length from several cm to more than 10 m (hugenholtz and lewkowicz, 2002; matsuoka et al., 2005). fig. 1 the location of sampling areas comparative grain-size measurements for validating sampling and pretreatment techniques… 41 ploughing blocks represent a form of mass movement when a block moves downslope faster than the surrounding material, resulting a mound on the front and lateral sides of the block, and a depression behind (french, 1996). occurence of ploughing blocks is associated with areas of active solifluction and frost-susceptible soils with low plasticity and liquidity limits (ballantyne, 2001). their size varies from several cm to almost 5 m (hall et al., 2001) and alongside the solifluction lobes they represent an ind icator of current periglacial phenomena (ballantyne, 2001; berthling et al., 2001). sampling sites were selected based on their elevation, aspect and geographic location. in all 54 sediment fig. 2 sampling of solifluction landforms: a. turf-banked lobe, b. ploughing block table 1 field and laboratory coding and origin of samples (a ploughing block, b turf-banked lobe) field id depth (cm) lab. id type mountain range field id depth (cm) lab. id type mountain range st136_a25 25 1. a tarcu c4_25 25 28. b fagaras t36_a20 20 2. a tarcu v1_25 25 29. b fagaras t36_b20 20 3. a tarcu c2_25 25 30. b fagaras t36_c20 25 4. a tarcu p1_25 25 31. b fagaras t36_d25 25 5. a tarcu c18_25 25 32. b fagaras t42_a25 33 6. a tarcu pa_d20 20 33. b fagaras t22_a33 23 7. a tarcu p8da_20 20 34. b fagaras mmlob_23 25 8. b tarcu p8da_80 80 35. b fagaras lc8_25 25 9. b cindrel p8d_riser2 20 36. b fagaras lc8_45 45 10. b cindrel p8da_60 60 37. b fagaras lc1_20 20 11. b cindrel p8db_25 25 38. b fagaras i_25 25 12. b iezer p8da_40 40 39. b fagaras i3_35 35 13. b iezer p8d_riser1 20 40. b fagaras brla12_a28 28 14. a fagaras pa19da_40 40 41. b fagaras brla12_b28 28 15. a fagaras pa19da_60 60 42. b fagaras brla12_c40 40 16. a fagaras pa19da_80 80 43. b fagaras brla12_d15 15 17. a fagaras pa19db_25 25 44. b fagaras brla12_e18 18 18. a fagaras pa19db_50 50 45. b fagaras s1_25 25 19. b sureanu pa19db2_25 25 46. b fagaras s1_45 45 20. b sureanu pa19da2_40 40 47. b fagaras p8_25 25 21. b fagaras pa19da2_80 80 48. b fagaras pa18a_25 25 22. b fagaras pa19da_110 110 49. b fagaras pa18b_25 25 23. b fagaras pa19da_100 100 50. b fagaras pa19db_riser 20 24. b fagaras p8da2_40 40 51. b fagaras pa19da_20 20 25. b fagaras p8da_75 75 52. b fagaras pa19db_45 45 26. b fagaras p8da2_80 80 53. b fagaras pa19da_105 105 27. b fagaras lp_25 25 54. b parang 42 serban et al. (2015) samples were extracted from 17 turf-banked solifluction lobes and from the front mound of 5 ploughing blocks for grain size and other sedimentological analyses (fig. 2). sampling depth ranged from 20 to 110 cm for turf-banked lobes and 15 to 40 cm for ploughing block mounds (table 1.). samples of approx. 0.5 kg were extracted by digging, thus samples were considered representative for later geomorphological comparisons, but might not be representative for stratigraphic analysis within the form. all the laboratory work was performed in the sedimentology laboratory of the department of physical geography and geoinformatics, university of szeged, hungary. from each sampling bag two subsamples (set a and set b) were extracted from different positions, weighing approximately 35 g, in order to test the representativeness of field sampling and to verify if the sample was collected from the same sediment layer. for every set of sample the same workflow was followed (fig. 3). samples were dried on 105°c, gently crushed, homogenised and dry sieved at a 2 mm mesh size for removing larger clasts and organic constituents. the fraction below 2 mm was analysed with a fritsch analysette 22 microtec laser diffraction equipment with a 0.08-2000 µm measurement range and 108 measurement channels. instrumental settings and protocols described by kun et al. (2013) were used throughout the measurement process. analyses were made in 3 steps for each parallel set of samples (fig. 3). firstly, the original untreated subsamples were analysed (step 1). subsequently, samples were treated with 10 % h2o2 for 1 day and a second run of measurements was performed after drying (step 2). finally, after a 1 day long 10 % hcl treatment a third run was also executed (step 3). acid treatment was aimed to ensure the complete removal of organic material, carbonates and to minimise the presence of aggregates. consequently, each sample was measured 6 times in all, the different measurements were identified by adding suffixes marking the set of samples and the steps of measurements (fig. 3). in the beginning of measurements the efficiency of ultrasonic treatment, made within the wet dispersion unit of the measurement device, was tested on 3 clayey, untreated samples, prone to be affected by aggregation. ultrasonification is very efficient in removing clay coatings, but it can also brake up quartz grains if the exposure is too long (di stefano et al., 2010). three sequential measurements were made, each preceded by 12s of treatment, then the results were compared. raw grain size data were exported and processed by software gradistat v8. grain size classes were identified following the udden-wentworth scale (udden, 1914; wentworth, 1922). for comparing different sets of samples and different steps of measurements cumulative distribution and the median diameter (d50) were primarily considered. textural properties were compared using the graphical method and the triangular diagram of folk (1954) and folk and ward (1957). subsequently the mean d50 value of different sample groups were an alysed in order to reveal general tendencies and diff erences related to parallel sampling and sample pr etreatment. results were also compared on the level of major grain size fractions (clay, silt, sand). finally, d50 data of different measurements were plotted against each other and correlation coefficients (r 2 ) were calculated in relation to a 1:1 linear function in order to determine the variability of the data and to provide further insight to factors modifying the mea surement results. fig.3 the steps of the measurement process and the identification of the different group of samples compared in the study results and discussion ultrasonic pretreatment regarding the median diameter of samples the mean relative difference between the first and third measurement cycles was 1.6 %, while maximum deviance was 3.3% (fig. 4). results were similar to those of kun et al. comparative grain-size measurements for validating sampling and pretreatment techniques… 43 (2013), using the same equipment, however, also corresponded well to the observations of di stefano et al. (2010), applying a longer ultrasound treatment. based on the above, the data of the third measurement cycle, preceded by a total 36s of ultrasonification, were used for further comparisons. it is assumed therefore that the applied treatment was adequate for the dispersion of clay aggregates and considering the results of chappell (1998) the breaking up of individual grains could be also avoided. textural properties and main fractions based on the measurements on untreated samples, all belonged to two textural groups: sandy mud and muddy sand (fig. 5.), representing 56 and 44% of the samples in case of set a and 59 and 41% in case of set b, respectively. if step 2 and step 3 results are taken a clear textural shift, i.e. fining due to disint egration can be noticed. as a matter of h2o2 treatment in case of both sets the proportion of the coarsest samples decrease by around 20%, and a new, finer textural group, mud also appears. following hcl treatment fining is still remarkable on a textural level, and finally 30 and 24% of samples from set a and set b can be described as mud, respectively. nevertheless, this time fining mostly affects sandy muds, and the proportion of muddy sands hardly changes. these trends are reinforced if results are co mpared concerning the main fractions, being very similar at both sets of samples throughout the whole measurement process (fig. 6). fining is evident in this case too: the proportion of sand continuously decrea ses while the proportion of silt increases, and the pr oportion of clay first increases then remains stable. it is also obvious already at this stage of the comparison that as pretreatment advances the difference between the results of set a and set b samples is increasing (fig. 6). these findings are in accordance with the results of kun et al. (2013) and di stefano et al. (2010). fig. 5 textural classification of samples at different steps of the analysis fig. 6 mean proportion of main fractions (clay, silt, sand) in both sets of samples at the different steps of the analysis fig. 4 cumulative (dashed lines) and frequency (columns) particle size distribution of sample c4, using an increasing length of ultrasonic dispersion (1): 12s; (2): 24 s, (3) 36 s 44 serban et al. (2015) consequently, acid pretreatment can significantly change even the textural properties of samples. at this stage of the analysis it is assumed that the removing of organic constituents rather affects the classification of coarser samples, while removing carbonates rather influences finer samples. nevertheless, it must be noted that textural shift is mainly because many of the samples are situated on the threshold between textural classes. in general the textural properties of the two parallel sample sets remained very similar throughout the measurement process. percentage deviations in median grain size concerning the entire dataset mean difference between the d50 value of a1 and b1 samples is 6.8% (0.53µm) in average. by pretreatment these values increase considerably and reach 23.7% (5.9µm) in case of a2 and b2 samples, while concerning a3 and b3 samples it drops back to 7.8% (1.9µm). differences are greater if the same set of samples are compared but with different pretreatment. for example in case of a1 and a2 samples the difference in d50 values is 33.7% (9.7µm) in average, while the same data for a1 and a3 samples are 14.3% (4.1µm). concerning the two acid treatment steps it seems as if samples were more sensitive for h2o2 (a1-a2 and b1-b2), showing a 33.7% and a 14.6% difference than for hcl etching (a2a3 and b2-b3): 22.7% and 9.3%. this emphasizes again the significance of acid pretreatment in changing the measured grain size distribution. if results are separated on the basis of morphology, in the case of ploughing blocks and turf-banked lobes the average difference between a1 and b1 sa mples is 0.5% and 8.4%, respectively. however, after pretreatment the two groups swap, and the difference between a3 and b3 samples changes to 36% and 2.3% (table 2). thus, in the case of ploughing blocks acid treatment ruined the coherence of the results, while in case of turf-banked lobes it improved significantly. it has to be resolved in the future if there is any genetic explanation to this phenomenon: higher organic matter or carbonate content, or greater spatial variability in grain size composition for example. when the main fractions are considered on their own, obviously the situation gets slightly better. concerning raw samples (a1 and b1) differences remain below 3%. as a result of acid treatment the greatest difference is experienced in the case of the clay fraction (table 2), being 23.4% and 15.8%. by the end of the measurement cycle the proportion of silt proved to be the most stable (3.7%) when the two sets of samples (a3 and b3) are taken. a similar relationship is seen if the different steps of measurements are compared within the same set of sample, namely the highest variability can be attributed to the clay fraction (42.1% and 32.2%), while silt provides the most steady data if the raw and fully treated samples (a1-a3 and b1-b3) are compared. however, if the two steps of treatment are considered separately (a1a2 and a2-a3 for example) it seems as if the sand fraction was less sensitive to acid pretreatment. the discrepancy is probably because the change in the sand fraction (decreasing abundance) is unidirectional at each step of treatment, while in the case of silt relative loss (silt particles turning into clay) and relative gain (sand particles turning into silt) can also occur, making the final result more comparable to the raw data. finally, in general it seems as if samples, with the exception of the sand fraction, were more sensitive for h2o2 treatment (a1-a2 and b1-b2) than for hcl treatment (a2-a3 and b2-b3). correlation analysis in order to check the consistency of comparative results correlation coefficients were calculated by plotting against the results of parallel measurements. values of r 2 supported and also supplemented the conclusions made on the basis of mean percentage deviations (table 3). if the full set of samples is considered, then r 2 is the highest between untreated a1 and b1 samples (0.71) and as pretreatment went on its value significantly decreased (table 3). if compared to changes in mean differences it must be noted that concerning the a3 -b3 pair lower mean difference is not followed by the increase of the r 2 value, i.e. hcl treatment did not improve the comparability of the samples in the end (t able 3). it is also noteworthy that the correlation d etable 2 mean percentage deviation of median diameter (d50) between different sample groups % difference median diameter (d50) main fractions all blocks lobes clay silt sand a1-b1 6.8 0.5 8.4 1.4 2.9 0.8 a2-b2 23.7 36.2 5.8 23.4 16.0 1.3 a3-b3 7.8 11.2 2.3 15.8 3.7 6.8 a1-a2 33.7 40.9 28.1 43.6 25.0 8.6 a2-a3 22.7 9.5 0.3 2.6 22.8 13.6 a1-a3 14.3 34.7 27.9 42.1 2.9 21.1 b1-b2 14.6 6.9 16.7 27.5 13.3 6.7 b2-b3 9.1 20.6 7.7 6.5 4.6 8.5 b1-b3 22.4 26.1 23.1 32.2 9.1 14.6 notes: set a and b: untreated (step1: a1 and b1), pretreated with h2o2 (step2: a2 and b2) and with hcl (step3: a3 and b3) comparative grain-size measurements for validating sampling and pretreatment techniques… 45 creased mostly after h2o2 treatment, the subsequent hcl etching just slightly affected the comparability of the samples. when correlations within the same set of samples are taken, the values of the two sample groups are significantly different. in the case of set a samples h 2o2 treatment influences much less r 2 values compared to set b samples, conversely, the hcl step introduces a much greater discrepancy (lower r 2 ) in case of set a samples than the other group. if raw and fully treated samples are considered (a1-a3 and b1-b3) the deviation in correlation coefficients is also striking (table 3), which might mean either that the mineral composition of subsamples was different, or acid treatment was not entirely consistent, however the same procedures were applied in each case. the discrepancy above can be further analysed if the different solifluction forms are considered separately. similarly to percentage deviations in median diameter ploughing blocks show a very good comparability on the level of the a1-b1 pair, which drops abruptly after the h2o2 step (a2-b2) (table 3). in case of turfbanked lobes r 2 values are very similar throughout the whole process, referring to more uniform mineral composition. if the two sets of samples are considered separately, a great variation can be seen in the effects of pretreatment, just as in case of percentage deviations described above. correlations were calculated for the main fractions as well. highest values were received for clay (0.96) and silt (0.94), for sand the r 2 value was somewhat lower (0.82) (table 3). in case of the clay fraction correlation coefficients between different sets of samples remained reasonably high throughout the whole analysis, which seemingly contradicts the trend experienced for percentage deviations (table 2). this might be because a slight change in median diameter can cause a significant difference in percentage deviations, while the r 2 value is less sensitive to this effect. based on the coefficients, the variability in the silt fraction increases significantly after h2o2 treatment, which is in harmony with the results received for percentage deviations. although r 2 values received for the sand fraction of untreated samples (a1-b1) is reasonably high, with the advance of pretreatment the largest variability is introduced by far here. actually, in the end, when results are plotted against within the same subsample group, no functional relationship can be identified (t able 3). this phenomenon is primarily due to the disintegration of particles as a result of hcl etching (a2 -a3 and b2-b3). conclusions in the present paper we investigated the representativeness of sampling in case of different solifluctional landforms, and the effect of acid pretreatment on ld grain size measurements. if the textural classification and fractional composition of subsamples is considered, the results show a high consistency between the two parallel measurements let they be made on untreated or pretreated samples. an overall fining as a matter of etching is evident. based on the experienced shifts between textural classes, fining as a result of h2o2 treatment is a greater issue in case of muddy sands, while fining as a result of hcl treatment is rather significant in case of sandy muds. this implies a compositional difference between samples falling to coarser and finer textural groups. either considering mean percentage deviations or correlation coefficients the comparability of the parallel measurements is best if samples remain untreated (a1b1). in this sense the sampling strategy in general is validated, however considering different landforms clear differences were experienced. while parallel untreated samples yielded very similar results in case of ploughing blocks, in case of turf-bank lobes a more careful and detailed sampling is proposed for further geomorphological comparisons, as probably large sa mples include more than one structural or stratigraphic elements of the landform. in case of the present samples pretreatment introduces a major uncertainty to further comparison and interpretation. in general relative deviation increases table 3 correlation coefficients of median diameter (d50) between different sample groups r 2 median diameter (d50) main fractions all blocks lobes clay silt sand a1-b1 0.71 0.93 0.69 0.96 0.94 0.82 a2-b2 0.49 0.24 0.72 0.80 0.47 0.60 a3-b3 0.42 0.37 0.78 0.87 0.72 0.47 a1-a2 0.81 0.22 0.86 0.75 0.32 0.63 a2-a3 0.39 0.34 0.37 0.70 0.24 0.16 a1-a3 0.26 0.12 0.17 0.62 0.28 0.08 b1-b2 0.46 0.62 0.50 0.77 0.57 0.56 b2-b3 0.80 0.93 0.92 0.77 0.50 0.09 b1-b3 0.60 0.70 0.61 0.55 0.23 0.08 notes: set a and b: untreated (step1: a1 and b1), pretreated with h2o2 (step2: a2 and b2) and with hcl (step3: a3 and b3) 46 serban et al. (2015) and correlation decreases as pretreatment advances. based on the analyses, hcl etching results a greater deviation and variability in case of the sand fraction, in turn h2o2 rather affects the silt fraction. this can partly be traced back to the geological background and composition of samples, namely the greatest deviations are experienced in case of landforms developed on crystalline limestone, and finer fractions are more likely to contain organic constituents of their size range. nevertheless, in several cases set a and set b samples exhibited different tendencies during the pretreatment process. this might imply either that organic and carbonate content could be different at parts of the relatively large samples, or the etching process was not entirely consistent. both possible reasons require further analysis. high variability of organic content can be explained by the stratigraphic observations of hugenholtz and lewkowicz (2002), kinnard and lewkowicz (2006), oliva et al. (2009), who revealed buried organic horizons, overlapping and deformed layers in solifluctional forms. consequently, organic matter and carbonate content determination as well as additioal mineralogical analyses can add further insight to the interpretation of discrepancies. meanwhile, by changing the parameters of acid pretreatment and making further comparative measurmeents the methodology of etching can be refined. finally, based on the results of the above research, we advise to make always multiple ld measurements on a representative group of samples from the entire sample set before the geomorphological or environmental interpretation of results. this way both sampling and sample processing can be validated, and the uncertainties of conclusions can be decreased. acknowledgements this work has been supported by the strategic grant posdru/159/1.5/s/133391, project “doctoral and post-doctoral programs of excellence for highly qualified human resources training for research in the field of life sciences, environment and earth science” cofinanced by the european social fund within the sectorial operational program human resources development 2007 – 2013”. the measurements and instrumentation was also supported by the huro/0901/266/2.2.2. project. references arnaud, f. 2005. discriminating bio-induced and detrital sedimentary processes from particle size distribution of carbonates and non-carbonates in hard water lake sediments. journal of paleolimnology 34, 519–526. doi: 10.1007/s10933-0056787-1 ballantyne, c.k. 2001. measurement and theory of ploughing boulder movement. permafrost and periglacial processes 12, 267–288. doi: 10.1002/ppp.389 berthling, i., eiken, t., sollid, j.l. 2001. frost heave and thaw consolidation of ploughing boulders in a mid-alpine environment, finse, southern norway. permafrost and periglacial processes 12, 165–177. doi: 10.1002/ppp.367 beuselinck, l., govers, g., poesen, j., degraer, g., froyen, l. 1998. grain-size analysis by laser diffractometry: comparison with the sieve-pipette method. catena 32, 193–208. doi: 10.1016/s0341-8162(98)00051-4 buurman, p., pape, t., reijneveld, j.a., jong, f. de, gelder, e. van 2001. laser-diffraction and pipette-method grain sizing of dutch sediments : correlations for fine fractions of marine, fluvial, and loess samples. netherlands journal of geosciences 80, 49–57. chappell, a. 1998. dispersing sandy soil for the measurement of particle size distribution using optical laser diffraction. catena 31, 271–281. doi: 10.1016/s0341-8162(97)00049-0 di stefano, c., ferro, v., mirabile, s. 2010. comparison between grain-size analyses using laser diffraction and sedimentation methods. biosystems engineering 106, 205–215. doi: 10.1016/j.biosystemseng.2010.03.013 folk, r.l. 1954. the distinction between grain size and mineral composition in sedimentary-rock nomenclature. journal of geology 62, 344–359. doi: 10.1086/626171 folk, r.l., ward, w.c. 1957. brazos river bar: a study in the significance of grain size parameters. journal of sedimentary petrology 27, 2–26. doi: 10.1306/74d70646-2b21-11d78648000102c1865d forde, j., collins, p.c., patterson, a., kennedy, r. 2012. comparison of granulometric methods and sampling strategies used in marine habitat classification and ecological status assessment. marine pollution bulletin 64, 1018–1028. doi: 10.1016/j.marpolbul.2012.01.036 french, h.m. 1996. the periglacial environment, harlow: addison wesley longman, 2nd ed., 341 p. goossens, d. 2008. techniques to measure grain-size distributions of loamy sediments: a comparative study of ten instruments for wet analysis. sedimentology 55, 65–96. doi: 10.1111/j.13653091.2007.00893.x hall, k., boelhouwers, j., driscoll, k. 2001. some morphometric measurements on ploughing blocks in the mcgregor mountains, canadian rockies. permafrost and periglacial processes 12, 219–225. doi: 10.1002/ppp.368 harris c. 2007. slope deposits and forms. in elias, sa (ed.). enc yclopedia of quaternary science, elsevier: amsterdam; 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rwanda: a case study in nyabihu district nathanael hafashimana1*, reuben jack sebego2, piet kebuang kenabatho2, rebecca nthogo lekoko3, joyce gosata maphanyane2 1roots & shoots rwanda, southern province, kamonyi district, runda sector, rwanda 2department of environmental science, university of botswana, 4775 notwane rd. gaborone, botswana 3department of adult education, university of botswana, 4775 notwane rd. gaborone, botswana *corresponding author, email: nathafas@gmail.com, p.o. box 404 kigali, rwanda research article, received 14 august 2022, accepted 6 october 2022 abstract landslides have become important environmental hazard in hilly regions of rwanda such as nyabihu district. they are characterized by the downslope movement of debris or other earth materials which damage or destroy everything found in their way such as infrastructure, croplands, and even cause a number of human deaths. the main triggering factors of landslides in rwanda are intense rainfall and land use/land cover (lulc) change. therefore, the objective of this study was to assess the lulc change effects on landslide occurrences. lulc maps of 2005 and 2015 were generated and overlaid with mapped landslides. maximum likelihood classification was used to classify the landsat satellite images. the results revealed a remarkable decrease of agricultural land, while all other lulc types have increased in the studied period. it was noted that most of the landslides occurred in agricultural land. the study results are expected to be useful for landslide hazard management decisions, land use planning and management regulations, so as to minimize the likelihood of landslide occurrences and their resultant impacts. keywords: geospatial techniques, gis, landslide hazard, land use, land cover, landsat imagery introduction landslides are among the globally recognized environmental hazards that cause numerous fatalities and property damages, particularly in mountainous or hilly regions of the world (huabin et al., 2005; bennett et al., 2016). worldwide, the severity and frequency of landslides differ from one region to another, depending on triggering factors or drivers either physical (e.g. rainfall, slope, and soil properties, etc.) or anthropogenic (e.g. loading the slopes with buildings and infrastructure, changing vegetation cover, etc.) present in the area (anderson and holcombe, 2013). various studies have grouped causative factors of landslides into internal and external causes (prasad, 1995; popescu, 1996; huabin et al., 2005). internal causes include factors such as faults, freezing and thawing of rocks and soils, material properties such as compressive strength and shearing strength, etc. whereas external causes include factors such as undercutting the foot of the hill slope when extracting minerals, excavating for creation of canals or roads, land cover change, exerting unbearable loads on slope such as buildings and water tanks, and also vibration induced by earthquakes, etc. thus, human activities like deforestation, vegetation clearance, improper agricultural practices, housing developments on steep slopes, road and railway construction, illegal mining, hill cutting, and dam constructions, etc., all have direct or indirect effects on slope failure which results in landslide occurrence (anderson and holcombe, 2013; dewitte et al., 2017; froude and petley, 2018). heavy rainfall, continuous land cover change mostly due to human activities, and other factors such as steep slope, soil depth and structure (clayey-sandy soils), and lithology (lateritic and volcanic) have been noted to induce landslides in hilly regions of rwanda (bizimana and sönmez, 2015; nsengiyumva et al, 2018). the landslide hazards have serious negative impact on socioeconomic livelihoods, devastating croplands and settlements as well as causing deaths. besides, landslides in rwanda often result in a lot of damages and people losing their lives, destruction of croplands, and also leaving injuries as well as homeless families. despite all this, few researches about landslide hazards have been done in the past (midimar, 2015; mininfra, 2015). rainfall patterns have been changing as a result of climate change which implies the severity of rainfallinduced landslides occurring in different parts of the country (muhire and ahmed, 2015; haggag et al., 2016). yet, the gravity of rainfall to cause landslide is also aggravated by human activities that destroy the natural land cover when growing crops or constructing houses in steep slope areas as result of population growth, and hence heightening the intensity, severity and frequency of landslides (rema, 2015). therefore, it is essential to analyze the relationship between lulc change and landslide occurrences. since rainfall and lulc change on steep slopes have been identified as the main triggering factors of landslides, assessing lulc change could assist in landslide hazard management. furthermore, the application of geospatial techniques in providing consistent landslide vulnerability maps in nyabihu district https://doi.org/10.14232/jengeo-2022-44169 mailto:nathafas@gmail.com 24 hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. has received limited attention so far. the application of these techniques could assist in assessing the extent and effects of landslide hazards in vulnerable areas such as nyabihu district, in western rwanda. therefore, the aims of this study were to assess (1) how lulc change affects landslide occurrences; (2) the extent to which lulc change affects landslide occurrences in nyabihu district of rwanda. study area nyabihu district (area: 537.7 km2) hosts nearly 294740 inhabitants with population density of 555 capita/km2. nyabihu district is located in western province of rwanda between latitude 1°40.443’ and 1°40.554’ south of the equator, and between longitude 29°38.295’ and 29°21.955’ east (fig.1). the district is characterized by a continental relief that consists of high, rocky and steep mountain slopes with an altitude ranging between 1460 m and 4507 m (minagri, 2018). in general, the study area presents a mild climate with an annual average temperature of 15℃, and it receives 1400 mm annual precipitation. the hydrological network of the district is comprised of several streams and springs, that are in deep, lowland valleys between steep mountains. in terms of vegetation, some parts of the study area are covered by exotic species such as eucalyptus on the hillsides and along the roadsides. other areas comprise agricultural fields with a variety of crops, and also grazing lands. the recently established gishwati national park in 2015 (which is dominated by indigenous species, and situated in the southwestern part of nyabihu district) has experienced deforestation (e.g. due to settlements, conversion of forest into agriculture and livestock farmlands) to the extent that the remaining intact natural forest is less than 7% of the original forest (minagri, 2018). materials and methods this study used quantitative research methods to analyze the rate of lulc changes, and the relationship between landslides and lulc change. the study applied remote sensing and gis techniques, and statistical analysis of the data. to achieve the objective of the study, mostly secondary data (satellite images, and shapefiles) were used. the main characteristics of the applied satellite images are in table 1. besides, high resolution google earth imagery of 2005 and 2015 were used to extract the geographical coordinates of visible landslides. the selection of the landsat images is explained by their long history and free availability compared to other satellites such as spot images. however, it was a challenge to find a good satellite image of the study area, as at this geographical location usually thick and fig. 1 the research was performed in nyabihu district of rwanda continuous cloud coverage is typical for almost all months of the year. the landsat satellite images of 2005 and 2015 were the sources of data from which geospatial techniques were applied to analyze the land cover change and produce land cover maps of the study area. these satellite images were downloaded from usgs (https://earthexplorer.usgs.gov/). as they were covering other areas that are not part of the study area, images were subsetted in order to have images covering only the study area. satellite image processing after downloading the required satellites images, layer stack and subset processes were done to prepare the images for further processing and analysis. erdas imagine 2018 software was used for carrying out the required preprocessing. the images of the study area were subset with the boundary shapefile of nyabihu district in erdas imagine 2018 software. different preprocessing techniques were used to prepare images for further processing and analysis. these include: radiometric correction, atmospheric correction and topographic correction. in the frame of radiometric correction the distortions in the degree of electromagnetic energy registered by each detector were removed or diminished (eastman, 2003). table 1 main characteristics of the satellite images used in the study image acquisition date path/row spatial resolution cloud cover landsat 7 etm+ 21. febr. 2005 173/61 30 m free of cloud cover (0%) landsat 8 oli 21. sept. 2015 173/61 30 m cloud cover of 10%, but free of clouds in the study area hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. 25 radiometric correction was carried out in order to calibrate the radiance of reflectance values in the images, and to allow more assessment of ground surface properties and then facilitate the analysis of the mentioned satellite images. with this, strips in landsat 7 etm+ were removed through the use of erdas imagine function which allowed overcoming the limitation of lacking information in strips, and hence increasing the certainty in analyzing the image. on the other hand, atmospheric correction was not much of concern in this study since post-classification comparison method that was applied for detecting lulc also compensates for variations in atmospheric conditions (mausel et al., 2004). using erdas imagine software, supervised classification was used to classify different lulcs in nyabihu district for the period of 2005 and 2015. specifically, supervised maximum likelihood classification technique was used in this study, because its relative simplicity and robustness, but also due to its ability to define means, variances and co-variances of training samples (gao and zhang, 2009). for the classification of images of the study area, more than 30 training samples for each lulc class were taken to ensure the representativeness of pixels. thereafter, recode tool in erdas imagine was used to correct the misclassified pixels during the classification process. this was done by using the google earth images for 2005 and 2015, which were linked to the classified images of the corresponding mentioned years in order to check the correctness of the classification results. after classifying the lulc classes for each image, the postclassification comparison method was utilized to detect lulc changes that have occurred between 2005 and 2015. post-classification comparison separately classifies multi-temporal images into thematic maps and then compares the classified images, pixel by pixel (mausel et al., 2004). accuracy assessment of the classified images was carried out. the overall kappa (k) statistics (table 2) of classified images are 0.82 and 0.88 for 2005 and 2015 respectively. identification of landslides in the study area since landslides spectral reflectance may be quite similar to bare land (such as exposed rocks, gravel roads, etc.) or ploughed fields, which could affect the accuracy of image classification results, google earth images were utilized to identify landslides in the study area by using computer screen-based visual image interpretation technique (xu, 2015). google earth imagery has high spatial resolution which helps accurately discern landslides from other ground features. visual image interpretation was chosen over supervised classification technique, because it helped to precisely locate landslides based on their rough texture and shape which differ from the one of surrounding ground features (e.g. vegetation, and rectangular shape of croplands). from google earth images of 2005 and 2015, the locations of landslides were determined and the coordinates were compiled in excel. then, landslides points were imported into arcgis to be processed and overlaid with classified images for further analysis. using these techniques, altogether 8 landslides were identified in google earth image of 2005 and 34 landslides were identified on the image made in 2015. results and discussion land use/land cover in 2005 the results of image classification of 2005 indicated that the study area was dominated (76.5%) by agricultural land (fig. 2, table 2). the study area is a rural district, where most of the inhabitants rely on growing crops or livestock keeping for their livelihood. the agricultural land occupying 411.67 km2 comprises the rain fed arable lands, cropland with non-permanent plants (e.g., potatoes, wheat, and vegetables) and permanent crops such as banana and tea plantations, and fallow fields as well. tea plantations (2.1%) were classified separately from the agricultural land as they appeared as a kind of vegetated area in the satellite image. tea plantations are located on hills and valleys in the south-west and central parts of the area. grasslands (5.3%) include the pasture lands and other uncultivable lands reserved for a specific purpose. they are typical in the sw corner of the study area, where they vary with forests. forests (13.7%) are mostly located on hills in the north-west and south-west of the study area. built-up areas (2.2%) comprise single residential houses spread throughout the study area, factories, roads, and other basic infrastructures such as schools, churches, health centers, etc. bare land (0.01%) occupying less space comprises the unused spaces, rocky areas and cleared areas. table 2 image classification accuracy assessment results of the applied 2005 and 2015 satellite images land use/cover type landsat 7 etm+ image (2005) landsat 8 oli&tirs image (2015) producer’s accuracy [%] user’s accuracy [%] producer’s accuracy [%] user’s accuracy [%] agricultural land 64.52 100 73.08 95 bare land 50 100 100 100 built-up 92.86 65 93.33 75.00 forest 89.47 85 86.96 100 grassland 90.91 100 100 85 tea plantation 93.75 75 94.74 90 water 100 84.21 100 100 overall accuracy 85% 90% overall kappa statistics 0.82 0.88 26 hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. fig. 2 land use/land cover in 2005 in nyabihu district and the areal distribution of these classes based on landsat-7 satellite image classification land use/land cover in 2015 despite changes that occurred in lulc since 2005, agricultural land in 2015 was still dominant (70.1%), followed by forest (15.8%) (fig 3). all together, they occupied 85.8% of the area (table 3). land use/land cover change from 2005 to 2015 the study area has undergone various changes in lulc between 2005 and 2015. approximately one tenth of the agricultural lands were replaced by other land uses, such as forest, grassland and built-up areas (table 3). the agricultural land decreased 34.46 km2 in this period, while forest, bare land, built-up, grassland, water, and tea plantation increased by 11.21 km2 0.8 km2, 1.66 km2, 17.77 km2, 0.92 km2 and 2.11 km2 respectively in the period (fig 4). the matrix of lulc change (table 4) shows more precisely, that which lulc category was fig. 3 land use/land cover in 2015 in nyabihu district and the areal distribution of these classes based on landsat-7 satellite image classification replaced by which category between the years 2005 and 2015. the diagonal in orange color on table 4 shows the size of the area (km2) that has not changed between the two years. for example, the area of agricultural land decreased from 411.69 km2 (76.47%) in 2005 to 377.23 km2 (70.07%) in 2015, but only 362.12 km2 of agricultural land remained unchanged between 2005 and 2015, and 17.86 km2 of the agricultural lands was converted to grassland, further 16.60 km2 became forest, and 10.93 km2 was built in. on the other hand, the total area of forests increased from 73.595 km2 to 84.80 km2 until 2015; whereas 64.45 km2 of forest remained unchanged in this period. the remarkable increase in forest and grassland areas (which are mostly pasture lands) was due to the measures that were taken by the government to reforest gishwati reserved forest. here, the reforestation efforts increased the area of forest from about 600 hectares in 2002 to 886 hectares between 2005 and 2008, which further increased up to 1,484 hectares between 2009 and 2010 (kisioh, 2015). the gishwati reserved 76.48% 0.01% 2.22% 13.67% 5.25% 2.05% 0.32% agricultural land bare land built-up forest grassland tea plantation water a b 70.08% 0.16% 2.53% 15.75% 8.55% 2.44% 0.49% agricultural land bare land built-up forest grassland tea plantation water a b 70.08% 0.16% 2.53% 15.75% 8.55% 2.44% 0.49% agricultural land bare land built-up forest grassland tea plantation water a b 76.48% 0.01% 2.22% 13.67% 5.25% 2.05% 0.32% agricultural land bare land built-up forest grassland tea plantation water a b hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. 27 forest was previously deforested by human encroachment through clearing of the forest for small-scale farming, large-scale cattle ranching projects and cattle grazing within the forest as well, as the resettlement of returnees and internally displaced people in the aftermath of the genocide in 1994 (kisioh, 2015). fig. 4 land use/land cover change and annual rate of change from 2005 to 2015 table 3 area and proportion of land use/land cover categories in 2005 and 2015 in nyabihu district, rwanda lulc 2005 2015 area change [km2] area [km2] proportion [%] area [km2] proportion [%] agricultural land 411.69 76.48 377.23 70.08 -34.46 bare land 0.08 0.01 0.88 0.16 0.8 built-up 11.95 2.22 13.61 2.53 1.66 forest 73.59 13.67 84.80 15.75 11.21 grassland 28.26 5.25 46.03 8.55 17.77 tea plantation 11.04 2.05 13.15 2.44 2.11 water 1.71 0.32 2.63 0.49 0.92 total 538.32 100.00 538.31 100.00 table 4 land use/land cover change matrix, representing the areal changes between 2005 and 2015 lulc classes lulc in 2015 [km2] agriculture bare land built-up forest grassland tea plantation water total area l u l c i n 2 0 0 5 [ k m 2 ] agriculture 362.1195 0.1980 10.9300 16.8089 17.8649 2.5734 1.1915 411.69 bareland 0.0092 0.0028 0.0004 0.0273 0.0202 0.0172 0.0001 0.0772 built-up 9.0412 0.0105 2.2301 0.4304 0.1534 0.0647 0.0170 11.947 forest 4.4268 0.1424 0.2808 64.4483 3.7750 0.4862 0.0354 73.595 grassland 0.4381 0.4709 0.0945 2.8881 24.1967 0.1724 0.0004 28.261 tea plantation 0.9120 0.0506 0.0724 0.1575 0.0180 9.8312 11.042 water 0.2835 0.0008 0.0352 0.0012 1.3857 1.7064 total area 377.2303 0.8752 13.6089 84.7957 46.0296 13.1450 2.6302 538.31 28 hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. likewise, the territory of built-up areas increased from 11.95 km2 in 2005 to 13.60 km2 in 2015. the increase of built-up areas was undoubtedly due to the population growth which definitely implies the construction of new infrastructures including shelters, etc. connection between land use/land cover change and landslides in nyabihu district the produced landslide shapefiles were overlaid with the lulc of nyabihu district in 2005 and 2015 (fig. 5). the results indicated more landslides (34) in 2015 compared to those occurred in 2005 (8). most of the landslides occurred in agricultural lands. for instance, in 2005, almost all landslides (7 out of 8, representing 87.5% of the total number of landslides) were located in agricultural land, and only one landslide (representing 12.5% of the total number of landslides) occurred under a forest cover. similarly, in 2015, most of the landslides (at 27 locations) developed on agricultural lands, while under grassland (4), built-up (1) and forests (2) only limited number of landslides appeared. this implies that agriculture land is the most affected by landslides compared to other land uses/covers; possibly due to depletion of natural vegetation. the lulc changes have an influence on slope failures that lead to landslides (chen and huang, 2012; mugagga et al., 2012), due to inappropriate land coverage for stabilizing the slope material firmly. more often, changes in lulc are associated with some factors like undercutting the slope, vegetation removal and change in water flow directions which all weaken the soil capacity of absorbing water, thereby causing landslides. former researches (e.g. karsli et al., 2009; reichenbach et al., 2014) proved that lulc changes on slopes contribute to slope instability and higher occurrence of landslide. the changes observed in the study area mainly refer to the decrease in agriculture land. yet, the agriculture remains the main source of subsistence for the majority people in nyabihu district. also, the agricultural production from this district feeds other regions countrywide, including kigali capital city. the decline of agricultural land may lead to improper agricultural practices, like cultivation of unsuitable slopes, as the farmers would be interested in producing more yield while violating the soil protection measures, and hence exposing soils to erosion and landslides as well. with the same reasoning, the diminution of agricultural land (cropland) while the population increases, explains the pressure exerted on remaining scarce cropland, and hence inducing inappropriate agricultural practices in one way or another. gurung et al. (2013) cited inappropriate agricultural practices as one of the landslide triggering factors, which might be the case in nyabihu district as well, based on the obtained results. it was also noticed by knapen et al. (2006) that the slope instability can be caused by cultivation on unsuitable steep slopes due to population growth pressure. the cultivation on steep slopes increases the chances to landslide occurrence when it is done without proper protection measures (wasowski et al., 2010, as cited in mugagga et al., 2012). in the study area a greater number of landslides was detected in agricultural lands (cropland) than on other lulcs, as the croplands in the area are mostly characterized by short-term crops (e.g. potatoes, beans, carrots) having roots with limited penetration depth of soil, though the progression of plant roots in the soil depth could increase the slope stability (noroozi et al., 2017). furthermore, based on the argument that trees or woody vegetation increase the slope stability (macneil et al., 2001; reichenbach et al., 2014), it confirms the prominent landslide occurrences in agricultural land, since growing crops usually involves the removal of trees or vegetation for soil preparation. fig. 5 relation between land use/land cover and landslides in 2005 (left) and 2015 (right) hafashimana et al. 2022 / journal of environmental geography 15 (1–4), 23–30. 29 the occurrence of landslides in croplands can be also attributed to other factors, such as the absence of radical terraces and appropriate rainwater channels on steep slopes. this was also revealed by the obtained results of the presented research, as it was indicated that almost all landslides occurred in agricultural land with steep slopes, while the agricultural land on gentle slopes experienced few landslides, confirming the relation of lulc and slope gradient in inducing landslides. conclusions this study analyzed the land use/land cover changes in nyabihu district of rwanda from 2005 to 2015. it was noted that there were various changes for each lulc category. the area of forests, grasslands, tea plantations, bare lands, and waters increased; while the territory of agricultural lands remarkably declined. the results proved the effects of lulc changes on landslide occurrences, where the agricultural land experienced the majority of landslides identified in the study area. changing lulcs, particularly into cultivation activities on steep slopes was noted to be among the factors that can easily destabilize the slope, and hence leading to landslides. based on the results, the study draws the following recommendations:  the government and other stakeholders should act together to promote efficient land uses aiming to minimize the possibility of landslide hazard occurrences.  the farmers should avoid improper agricultural practices on steep slopes  consideration should be taken into proper canalization of water, especially rainfall related run-off that could erode the top soil and hence causing the instability of the slopes.  the conservation measures focusing particularly on soil protection should be promoted.  radical terraces are specifically recommendable on steep places that are not yet terraced, as they have been proven essential in weakening the damaging capacity of the rainfall water flowing down the steep slopes. references anderson, m. g., holcombe, e. 2013. community-based landslide risk reduction: managing disasters in small steps. world bank publications. bennett, g. l., miller, s. r., roering, j. j., schmidt, d. a. 2016. landslides , threshold slopes , and the survival of relict terrain in the wake of the mendocino triple junction. geology 44(5), 1–4. doi: 10.1130/g37530.1 bizimana, h., sönmez, o. 2015. landslide occurrences in the hilly areas of rwanda, their causes and protection measures. disaster science and engineering, 1(1), 1–7. online available at http://www.disasterengineering.com/tr/download/articlefile/408168 chen, c., huang, w. 2012. land use change and landslide characteristics analysis for community-based disaster mitigation. environ monit assess., 185, 4125–4139. doi: 10.1007/s10661-012-2855-y dewitte, o., bibentyo, t. m., balegamire, c., basimike, j., matabaro, s. k., delvaux, d., kervyn, f. 2017. landslide hazard in bukavu (dr congo): a geomorphological assessment in a datapoor context. geophysical research abstracts, 19, 3–4. eastman, j. r. 2003. idrisi kilimanjaro: guide to gis and image processing. clark university: worcester, ma, usa. 306 p. froude, m. j., petley, d. n. 2018. global fatal landslide occurrence from 2004 to 2016. nat. hazards earth syst. sci., 18(8), 2161–2181. doi: 10.5194/nhess-18-2161-2018 gao, y., zhang, w. 2009. a simple empirical topographic correction method for etm + imagery. international journal of remote sensing, 30(9), 2259–2275. doi: 10.1080/01431160802549336 gurung, a., gurung, o. p., karki, r., oh, s. e. 2013. improper agricultural practices lead to landslide and mass movement disasters: a case study based on upper madi watershed, nepal. emir. j. food agric, 25(1), 30–38. doi: 10.9755/ejfa.v25i1.5341 haggag, m., kalisa, j. c., abdeldayem, a. w. 2016. projections of precipitation, air temperature and potential evapotranspiration in rwanda under changing climate conditions. african journal of environmental science and technology, 10(1), 18–33. doi: 10.5897/ajest2015.1997 huabin, w., gangjun, l., weiya, x., gonghui, w. 2005. gis-based landslide hazard assessment: an overview. progress in physical geography: earth and environment, 29(4), 548–567. doi: 10.1191/0309133305pp462ra karsli, f., atasoy, m., yalcin, a., reis, s., demir, o., gokceoglu, c. 2009. effects of land-use changes on landslides in a landslideprone area (ardesen, rize, ne turkey). environmental monitoring and assessment, 156(1–4), 241–255. doi: 10.1007/s10661-008-0481-5 kisioh, h. 2015. gishwati forest reserve, three years interim management plan 2015-2018. rwanda. knapen, a., kitutu, m. g., poesen, j., breugelmans, w., deckers, j., muwanga, a. 2006. landslides in a densely populated county at the footslopes of mount elgon (uganda): characteristics and causal factors. geomorphology, 73, 149–165. doi: 10.1016/j.geomorph.2005.07.004 macneil, d. j., steele, d. p., mcmahon, w., carder, d. r. 2001. vegetation for slope stability. trl report 515, trl, crowthorne. mausel, p., brondízio, e., moran, e. 2004. change detection techniques. international journal of remote sensing, 25(12), 2365–2407. https://doi.org/10.1080/0143116031000139863 midimar 2015. the national risk atlas of rwanda. republic of rwanda, ministry of disaster management and refugee affairs (midimar). online available at: https://www.gfdrr.org/en/publication/rwanda-national-riskatlas minagri. 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evaluated the conditions for selecting landfill sites; and determined suitable landfills in ajaokuta, nigeria. data for the study were sourced from sentinel-2a, 2021. integrated gis-based analysis using multi-criteria evaluation method was employed to scrutinise the appropriateness of the existing dumpsites for siting landfills. however, with reference to federal environmental protection agency (fepa) guidelines, results of buffering and proximity analyses indicated that none of the existing dumpsites could be converted to landfill sites. moreover, a fuzzy overlay of all the criteria considered was employed to identify and propose the most suitable areas for solid waste disposal sites in the study area. based on the official stipulated distance, new sites were proposed for landfills. the study emphasised the increasing mounds and improper disposal of municipal solid wastes in nigerian urban centres which have become too agonising and repulsive to sights. nevertheless, if the recommendations of this study are taken with utmost seriousness, any unexpected outbreak of epidemic and environmental pollution will be greatly avoided in the study area. keywords: solid waste management, dumpsite, landfill, urban area, site suitability, multi-criteria decision analysis introduction land use and landcover are often used interchangeably, however, each term has its own unique meaning. landcover refers to the surface cover on the ground like vegetation, water, bare soil, wetlands and impervious surfaces (comber et al., 2005). land use, on the other hand, is used to describe the human use of land; it refers to the purpose the land serves (comber et al., 2005; fisher et al., 2005). when used together, land use/landcover (lulc) implies the categorisation or classification of human activities and natural elements on the landscape within a specific time frame. landcover changes with alteration in the environment such as improper solid waste management. indiscriminate dumping of wastes, whether liquid or solid and whether domestic or industrial, is not limited to just a part or region of the world. though in the developed countries with many industrial establishments and advanced technologies, there is evidence of organised waste management (chung & lo, 2008; shamim & muzafar, 2014; srivastava, 2016; usman, 2017; suleiman et al., 2019). yet, studies have shown that inadequate collection and unrestrained dumping of wastes persist in many of these countries (aderoju, 2014; chen et al., 2017; nascimento et al., 2017; andrew et al., 2018). the situation of poor waste management is reportedly worse in the less developed countries where there are high rates of threat of the adverse effects of improper management of solid wastes (chokor, 1993; ajibade, 2007; ayaim, 2019; mekuria et al., 2019). landfills have been acknowledged as an appropriate method of organised solid waste disposal in urban areas (ebistu & minale, 2013; zadawa et al., 2015; osei et al., 2016; jibril et al., 2017; ezeudu, 2020). however, many countries are yet to adopt the strategy because of the technical expertise required in the design, operation and monitoring that will ensure compliance with environmental regulations. in this regard, the roles of geographic information system (gis) in selecting appropriate locations for landfills have been emphasised. there are several gis techniques that have been applied to the problem of locating landfill sites more efficiently. for instance, multi criteria decision analysis (mcda) has been employed with great successes in some countries (akbari, 2011; jayprakash et al., 2015; motlagh & sayadi, 2015; el maguiri et al., 2016; al-anbari et al., terseer & bibi, 2017; 2018; ajibade et al., 2019; karimi et al., 2019; rezaeisabzevar et al., 2020), analytical hierarchical process (ahp) method (siddiqui et al., 1996; saaty, 2008; djokanovic et al., 2016; randazzo et al. 2018; yakubu & zhou, 2018; kamdar et al., 2019; sener & sener, 2020; sulemana et al., 2020; younes, 2020), and integration of a median ranked sample set and an analytic network process (mrss-anp) methods (husby et al., 2005; younes et al., 2015). furthermore, while idowu et al. (2012) adopted macromedia and graphical user interface (gui) approaches, demesouka et al. (2016) considered measuring attractiveness by a categorical based evaluation technique (macbeth) technique appropriate for analysing gis-based landfill site suitability. also, saeedi et al. (2019) employed multiple attribute decisionmaking (madm) methods which is a combination of https://doi.org/10.14232/jengeo-2008-43938 mailto:olaadewale1@gmail.com 2 olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. fuzzy-analytical hierarchy process and ordered weighted average (fahp and owa) to assess the choice of landfill site for solid drilling waste of an oilfield in southwest iran. in nigeria, the federal environmental protection agency (fepa) was established in 1999 and was reorganised as environmental protection agency (epa) in 2006. the agency is responsible for, among other functions, ensuring that wastes are disposed in an environmentally responsible manner. this includes ensuring that existing and potential landfill occupiers are aware of the risks landfill poses to the quality of air, water and land resources (fepa 1999; epa 2006; usman 2017). therefore, the landfill occupiers are responsible for the management of the risks in the most effective way possible (zadawa et al., 2015; sridhar, 2017; suleiman, 2019). the guideline stressed that selection of a landfill cannot be confirmed prior to completion of feasibility study and environmental impact assessment (eia) of the site. also, it is pointed out that there should be consideration for land use and landcover types, particularly natural vegetation and cultivated land. however, the guidelines allow a reasonable comparison and retention of alternate sites if the preferred site proved unworkable (ladan, 2007; suleiman, 2019). to improve the level of waste management and to ensure a beautiful and clean nigeria, epa (2006) highlighted some guidelines for a more organised waste management system in the country. the guidelines specify that potential landfill sites can be selected based on the suitability of the area. the minimum criteria specify that a landfill should be: i. 200 metres away from all surface water; ii. 100 metres away from all transport routes; iii. 2,500 metres buffer zone around all buildings; and iv. slope of the area should be between 8º and 10º. ajaokuta is the home of the largest steel company in nigeria called ajaokuta steel company (asc). as a result of increase in economic activities brought about by the large iron and steel company, there has been a very rapid growth of municipal solid wastes in ajaokuta. most of the waste generated from households and companies is dumped along river courses and roads. thus, the need arises to site solid waste landfills in ajaokuta. to do this effectively and following the epa (2006) standard, this study used integrated gis-based analysis to assess the criteria for selecting suitable sites for solid waste landfills in ajaokuta, nigeria. to achieve this, the study identified the location of existing dump sites in ajaokuta; evaluated the parameter for landfill locations; and suggested landfill sites in the study area. this study will educate the general public, stakeholders in environmental management and policy makers on the problems of solid waste management. study area ajaokuta is the headquarters of ajaokuta local government area, kogi state, nigeria. it is located on the left bank of river niger between latitudes 7° 31'n and 7° 38'n, and; longitudes 6° 35'e and 6° 43'e (fig. 1). the population of ajaokuta in according to the 2006 census was 122,321 over a land area of about 1,362 km2 square fig. 1 the study area. sources: sentinel2a (february, 2021), field research, 2021, openstreetmap (accessed on august 25, 2021) olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. 3 (national population commission of nigeria, npc, 2006). most of the residents in ajaokuta are engaged in the civil service and farming, at subsistence levels. ajaokuta is in the tropical zone characterised by two climatic conditions; rainy and dry seasons. while the annual rainfall is between 1100 mm and 1300 mm, the annual average temperature of 36.7 °c (agbor & shehu, 2013; tokula & eneche, 2018). the vegetation is guinea savannah containing tall grasses and few trees (adegbe et al., 2014; tokula & eneche, 2018). materials and methods this study used secondary data derived from sentinel-2a, imagery (2021), open street map (osm) of ajaokuta (accessed, 25 august, 2021), google earth (ge) map (accessed, 12 september, 2021) and digital elevation model (dem) acquired from shuttle radar topography mission (srtm). based on epa regulations, four factors influencing siting of landfills were selected for this study. proximities of landfills to the built-up area, transport network and waterbodies were extracted from osm of ajaokuta. slope was derived from dem data to evaluate landfill siting suitability. this was complemented with field survey using handheld gps receiver used to obtain the coordinates of the existing dump sites and digital camera which was used to record and show their exact locations. sentinel imagery was processed using digital image processing techniques with a view to increase the pictorial quality of the image and to clearly identify various landcover in the study area (braun, 2020; muhammed, 2020; wu et al., 2020; lu 2021 et al.). the study area map was clipped out from the pre-processed sentinel-2a, which has been set to world geodetic survey (wgs) 1984, universal transverse mercator (utm) zone 31n. thereafter, false colour composite was adopted to enable visual interpretation of the wavelengths (mishra et al., 2016; lyons et al., 2018). following a modified version of maximum likelihood classification methods, the area was classified into five different landcover classes: water body, dense vegetation, light vegetation, built-up and bare land. the false colour composite was used to distinguish between vegetation and farmland; while vegetation is usually in deep (dark) red, farmlands are light (bright) red. using arcmap 10.6 software, on-screen digitizing was done to create shape files for all features of interest extracted from osm. in addition, existing dumpsites coordinates taken during the field survey were also plotted and then converted to shape files. accuracy assessment was conducted to ensure accurate interpretation of the data obtained from remotely sensed sources, sentinel-2a and srtm data. these data were validated using ge map, ground truthing and visual interpretation. ge map of the study area was downloaded and digitised to extract 65 reference points for imagery validation exercise (table 1). these points were exported into arcgis as .kml files and used to validate and confirm the accuracies of data obtained from remotely sensed sources. also, remotely sensed data were evaluated through ground truthing and visual interpretation. by this, gps was used to take and record geographic coordinates of 90 control points in the study area (table 1). in arcgis environment (arcmap 10.6 software), these points were converted from vector to raster data and integrated with stable images to produce a confusion matrix (lyons et al., 2018; chen et al., 2019; congalton & green, 2019; braun, 2020). the landcover classification method was initiated through the clipping of the satellite imageries using a vector map of the administrative boundary of the study area. supervised maximum likelihood classification was performed using arcmap image processing tool in arcgis environment. five lulc types were identified from the images, these are water body, dense vegetation, light vegetation, built-up and bare surface (table 2). results of the classification were used to analyse landcover statistics, the distance between the existing dumpsites and the evaluation criteria using attribute table and field calculator tools in arcgis. generally, the slope of ajaokuta ranges between 0º and 89.9º (shuttle radar topography mission, srtm). the slope of the area was grouped into three convenient classes based on epa recommendation that the slope of a landfill should be between 8º and 10º: i. less than 8º ii. 8º 10º; and iii. higher than 10º. table 1 distribution of validation points (by lulc) s/n lulc class no. of points googleearth map ground points 1 water body 12 20 2 dense vegetation 15 20 3 light vegetation 13 15 4 built-up 15 25 5 bare land 10 10 total 65 90 sources: googleearth map (accessed on 12 september, 2021), ground truthing (2021) table 2 landcover classification schema s/n lulc class land use/cover 1 water body river, stream, pond, lake and any other kind of surface water 2 dense vegetation orchards, mixed forest and plantation 3 light vegetation grass, nurseries, farmland/crop land 4 built-up residential, commercial, industrial and transportation 5 bare land sandy area, paved surface, and open land source: sentinel-2a, (february, 2021) 4 olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. to facilitate easy comparisons, values of all the constraints for analysis were standardised to a common scale using byte scale in a range of 0–255; where 0 = least suitable and 255 = most suitable (eastman, 2003; makropoulos & butler, 2006; mahini & gholamalifard, 2006; ferretti & pomarico, 2013). then, the criteria scores were standardised using fuzzy membership functions in arcgis environment (tuzkaya & gulsu, 2008; sener & sener, 2020). the decision on which function should be used for each criterion was based on epa guidelines. furthermore, the weight of each criterion was determined using analytical hierarchy method of ranking/rating procedure (malczewski & rinner, 2005; sulemana et al., 2020). the rankings were standardised to numerical weights on a scale 0 to 1 with overall summation of 1. by this, the four criteria of surface water, transport routes, buildings (built-up area) and slope were ranked based on their importance to landfill site selection as stipulated by epa (2006). vegetation, though not a criterion for analysis in this study, was included as a fifth criterion in the ranking because it is a major component in the area consisting of both the natural and artificial features. all the criteria were aggregated in weighted linear combination (equation 1), which is the most used decision rule (mahini & gholamalifard, 2006; malczewski & rinner, 2015). 𝑆 = σ𝑤𝑖𝑥𝑖 × 𝜋𝑐𝑗 (1) where: s = composite suitability score, xi = factor scores (cells), wi = weights assigned to each factor, cj = constraints (or boolean factors), ∑ = sum of weighted factors, π = product of constraints (1-suitable, 0-unsuitable). this was applied in gis raster calculator s = [(c1 * 0.50) + (c2 * 0.30) + (c3 * 0.10) + (c4 * 0.07) + (c5 * 0.30)] * cons_boolean c1 to c5 and cons_boolean are thematic layers representing the factors and constraints. the reliability of the results was validated through ground truth verification. after weightings have been applied, the aggregation of all the criteria considered for analysis were fuzzified using a fuzzy overlay. by this, good sites for landfills in the study area are those areas that fall within the 8º 10º class and satisfy other conditions as specified by environmental protection agency (2006). in effect of the foregoing, the basic spatial analysis employed in this study was buffering operation in which criteria were analysed in the arcgis environment. buffers of specific distance were created around the dumpsites to determine their proximity level to the transport routes, rivers and the built-up areas. slope analysis of between 8º and 10º was considered to determine areas with the best slope suitable for landfill. results results of accuracy assessment table 3 indicates that water body had the highest accuracy (both ua and pa recorded 100%). with overall accuracy of 94.88% and kappa value of 0.860, therefore there are high significant agreements between the reference points and the extracted classes (mis hra et al., 2016; congalton & green, 2019; braun, 2020). general pattern of landcover in the study area figure 2 shows the general pattern of landcover in the study area. based on the objectives of this study, the whole area was classified into vegetation, waterbody, bare land and built-up area. vegetation class includes all parts containing both usual and reproduced vegetal cover. therefore, vegetated area was divided into sparse and dense classes for the purpose of differentiating between vegetation and cultivated or secondary regrowth. for instance, whereas vegetation includes all wilderness areas, cultivated or secondary regrowth comprises grazing or pasture land, farmlands, fields and open green spaces. waterbody in the area are largely rivers and streams of which river niger is the major drainage system. bare land includes outcrop areas, paved surfaces, open top soils impervious surfaces and all other areas, asides built-up and waterbody, that are not vegetated. the built-up area includes residential, industrial, commercial and all other areas containing buildings (regardless of the quantity and quality of the buildings). table 4 shows the proportion of each landcover in the study area. most of the area consisted of light vegetation which could have been used for farming activities or any other open green field. of the 1364.41km², only 216.67 km² (representing 15.88% of the total land area) was built up with the greatest concentration of development in the eastern part of the area. however, there were dispersed development of the built-up land use in the northern section, some parts of the west and the central segment of the southern area. the southwest and north-western parts of the study area are devoid of any human habitation (fig. 2). table 3 confusion matrix for landcover classification (2021) source: sentinel-2a, (february, 2021) lulc classes classification accuracy (%) user’s accuracy producer’s accuracy water body 100 100 dense vegetation 87.5 90.1 light vegetation 84.2 100 built-up 100 89.7 bare land 93 85 overall accuracy 94.88 kappa index (ki) 0.860 source: sentinel-2a, (february, 2021) olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. 5 location of existing dumpsites in ajaokuta the major system of waste disposal in the study area was open dumpsites; there was no land fill in ajaokuta. table 5 contains the locations and nearness of the present major dumpsites in ajaokuta to the nearest selected criteria for assessment. the distances were calculated in arcgis and verified with a handheld gps with accuracy of not more than 4%. at individual level of assessment, some of the existing dumpsites might just be suitable for landfills. for instance, considering slope criterion, dumpsites d1, d2, d13 and d14 are located within the slope range of 8° 10° and can accommodate landfills. also, on account of waterbody factor, only d15 and d20 were too close at 250 m minimum setback to surface water; all other areas are suitable for landfills. moreover, using transport route as primary criterion, only site d11 was found at a distance below the minimum setback of 100 m. all the twenty dumpsites in the study area were found either within settled area or at a very short distance from the built-up area, therefore, none of the sites is suitable for landfill based on buffer zone of 2,500 m from built -up area. figure 3 indicates that the dumpsites were located close to transport routes, buildings and water bodies. dumpsite d11 at bb market was located almost on the road at a short distance of 14.2 m. however, based on the criteria selected for analysis, these are unsuitable areas for siting a landfill (table 5). in effect of these observations, none of the existing dumpsites fits the criteria for siting a land fill, therefore, it is imperative to find suitable sites. selection of suitable landfill sites in ajaokuta the variables considered in the final suitability map are: distance to surface water, proximity to building, distance to transport route and slope. the built-up area was buffered at 2500 m (fig. 4a). the purpose is to create adequate set back between dwelling areas and the landfill sites to avoid any form of pollution. the areas outside the buffered zone are potential areas for siting of landfills because they are out of the restricted areas. furthermore, roads were buffered at 100 m in order to consider aesthetics and safety (fig. 4b). moreover, in order to mitigate conflicts relating to the fig. 2 landcover in ajaokuta source: sentinel-2a (february, 2021) table 4 landcover classes of ajaokuta lulc classes area (km²) % water body 47.48 3.48 dense vegetation 82.96 6.08 light vegetation 844.7 61.91 built-up 216.67 15.88 bare land 172.6 12.65 total 1364.41 100.00 source: generated from figure 2 based on sentinel-2a (february, 2021) fig. 3 spatial pattern of existing dumpsites in ajaokuta sources: sentinel-2a (february, 2021), openstreetmap (accessed on august 25, 2021) 6 olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. contamination of sources of water supply, surface water bodies were buffered at 200 meters (fig. 4c). the slope height is an essential parameter that must be considered in case of flood which can lead to water pollution, too low or steep slopes must be avoided in the selection of landfill sites (fig. 4d). areas with slope of 0° to 7.9° are considered as too low for siting landfills because they may be undulating terrain or, even a basin, that would not encourage such an earth drilling landscape. also, areas with slope above 10° are too steep and may accelerate erosion and consequently, may result in flooding. in fig. 4d, these are the yellow and white portions, respectively. furthermore, fig. 4d indicates relatively level land areas with slope between 8º and 10º as green where landfill can be sited. however, it might be dangerous to compare data at different measurement levels. therefore, using analytical hierarchy method of ranking/rating procedure, a standardised data of the five ranked criteria for landfill site selection was produced (table 6). buildings/built-up area (c1) was the most important criterion while c5 (vegetation) was the least important (table 6). vegetation had the least weight since it was not even a factor for consideration. nevertheless, vegetation must be retained in the analysis to maintain a balance of 100% score and 1.0 weight aggregate. figure 5 is a fuzzy overlay of all the four criteria (road, water body, built-up area and slope) considered for analysis in this study. based on epa (2006) requirements for siting landfills in nigeria, all the grey areas are not suitable for landfill sites on account of too low (below 8°) or too steep (above 10°) slope and proximity to human habitation, surface drainage system and closeness to transport routes. to avoid all kinds of environmental and health problems, it is very important to abide by all the laid-down rules and regulations, available guidelines and stipulated criteria for siting landfills (dijkstra et al., 2018). considering the criteria for evaluation, areas marked green in figure 5 are the appropriate sites for locating landfills in the study area (epa, 2006). table 5 proximity of existing dumpsites to the nearest selected criteria for evaluation dumpsite tag location of dumpsite slope (in degrees) distance (in metres) remark built-up area water bodies transport route d1 adogo 9.8 118.3 2951.7 715.9 not suitable d2 adogo station 9.4 within 3227.9 565.0 not suitable d3 idibo 6.9 within 2166.9 422.7 not suitable d4 ascl 3.3 within 877.9 628.2 not suitable d5 ascl 3.1 within 654.7 499.5 not suitable d6 ascl 5.7 within 1288.2 103.5 not suitable d7 african camp 7.1 within 2,893.6 860.2 not suitable d8 dumez 3.7 within 3,098.2 1,793.8 not suitable d9 mechanic village 16.4 within 5,383.6 953.8 not suitable d10 mechanic village 7.3 within 3,640.8 762.9 not suitable d11 bb market 5.9 within 396.9 14.2 not suitable d12 bb market 5.6 within 825.5 383.3 not suitable d13 roja 8.4 71.8 1,467.1 689.0 not suitable d14 kuroko 9.2 within 418.7 627.1 not suitable d15 geregu 1.3 within 243.6 115.3 not suitable d16 eganyi 14.8 within 2706.4 516.7 not suitable d17 onado 5.4 within 1766.5 360.3 not suitable d18 ilubusechi 2.7 within 2225.2 573.5 not suitable d19 old camp 7.6 13.7 1,792.1 731.0 not suitable d20 ero 0.6 within 51.2 579.6 not suitable sources: shuttle radar topography mission (srtm), sentinel-2a (february, 2021), openstreetmap (accessed on august 25, 2021), field research, 2021 table 6 standardised data for landfill site selection criterion no criteria/constraints score (%) weight suitability values buffer (m) c1 buildings (built-up area) 50 0.5 decreases with distance to buildings 2,500m c2 surface water 30 0.3 decreases with distance to surface water 250m c3 transport routes 10 0.1 decreases with distance to transport routes 100m c4 slope 7 0.07 decreases with increase in elevation 8º 10º c5 vegetation 3 0.03 source of nectar and pollen total 100 1.0 source: field research, 2021 olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. 7 fig. 4 buffering around the considered landfill siting criteria. a) 100 metres buffer around all transport routes. b) 200 metres buffer around all surface water. c) 2,500 metres buffer zones around all built-up areas. d) slope of the area sources: sentinel-2a (february, 2021); shuttle radar topography mission (srtm), openstreetmap (accessed on 25 august, 2021) 8 olayiwola and suleiman 2022 / journal of environmental geography 15 (1–4), 1–10. fig. 5 fuzzy overlay of the considered landfill siting criteria sources: sentinel-2a (february, 2021), openstreetmap (accessed on august 25, 2021) discussion solid wastes are not properly disposed in ajaokuta, nigeria; the open dump solid waste disposal practice is not in accordance with the best principles of public health and environmental protection. thus, this study employed the use of geospatial technology to acquire information on dumpsites in ajaokuta with the hope that it will enable proper monitoring and management of the existing dumpsites. this was with the view of preventing environmental hazards which might cause disease outbreak. also, geospatial technology was used to determine the location of the most suitable place for landfills so that a healthy environment can be maintained in ajaokuta. this study used osm and remotely sensed data to analyse and map out the possible sites for landfil ls in ajaokuta, nigeria. proposed landfill sites were determined using buffering analysis of the dumpsites at 100 m, 200 m, and 2,500 m around roads, rivers/watercourses and built-up areas, respectively. however, all of these were ascertained on slopes tha t are between 8º and 10º. the results indicated that many parts of ajaokuta, nigeria are not suitable for the siting of landfills. the study area presents low suitability for siting landfills because of large network of transport routes, wide expanse of the built-up area and availability of many surface waterbodies. furthermore, the slope of the area did not permit landfill to be sited in most parts of the industrial town. this implies that very little land is available and suitable for landfill in the study area. this is not different from some previous observations (mahini & gholamalifard, 2006; jibril et al., 2017) which established that only sizeable areas are suitable for landfill development within their respective study areas. results of buffer operation indicated that all the existing dumpsites are unsuitable locations to accommodate landfills in ajaokuta. through the spatial multi-criteria analytical methods adopted for this study, it was revealed that there are quite a few sites within the iron and steel industrial town of ajaokuta, nigeria where landfills can be located. subsequently, two major areas were identified in the northern and southwestern parts as the most suitable sites for siting of landfills. however, outside these two major areas, there are a few other possible landfill sites, especially, in the western and central parts of the study area. this result corresponds with the findings of other studies that have found the existing dumpsites as unsuitable possible suitable sites for establishing a dumpsite in their respective study areas (ebistu & minale, 2013; zulu & jerie, 2017; krčmar et al., 2018). conclusion this study observed that the proposed landfill sites in the industrial town of ajaokuta, nigeria are easily accessible, far away from human dwellings and at safe distances from any surface water. the proposed landfill sites are in relatively dry areas, bare land with light vegetation (mostly, agricultural land) where the slope is between 8 and 10 degrees. nevertheless, it is important to note that areas to be used for landfill may gradually become less accessible with progressing time and might result in great increase in the costs of disposing wastes and high level of environmental risks. therefore, to improve the quality of urban environment as well as that of life of the inhabitants, there should be proper land use planning which, in turn, should lead to efficient land use. also, there is the need to update, improve and increase the level of waste management services in ajaokuta. overall, the use of 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https://doi.org/10.1007/978-3-030-45263-6_5 https://doi.org/10.18533/rss.v2i4.99 introduction study area materials and methods results results of accuracy assessment general pattern of landcover in the study area location of existing dumpsites in ajaokuta selection of suitable landfill sites in ajaokuta discussion conclusion references analysis of pattern and extent of deforestation in akure forest reserve, ondo state, nigeria journal of environmental geography 12 (1–2), 1–11. doi: 10.2478/jengeo-2019-0001 issn 2060-467x analysis of pattern and extent of deforestation in akure forest reserve, ondo state, nigeria isaac adelakun gbiri1*, nathaniel olugbade adeoye2 1department of geographic information systems, federal school of surveying (fss), pmb 1024, 211212 oyo, oyo state, nigeria, 2department of geography, obafemi awolowo university, pmb 13, 220282 ile-ife, osun state, nigeria *corresponding author, e-mail: isaac.babatunde6@gmail.com research article, received 7 july 2018, accepted 22 february 2019 abstract forest reserves in southwestern nigeria have been threatened by urbanization and anthropogenic activities and the rate of deforestation is not known. this study examined the vegetation characteristics of akure forest reserve using optical remote sensing data. it also assessed the changing pattern in the forest reserve between 1986 and 2017. global navigation satellite system (gnss) receiver was used to capture the location of the prominent settlements that surrounded the forest reserve in order to evaluate their effects on the forest. landsat tm 1986, landsat etm+ 2002 and landsat oli_tirs 2017 with 30m resolution were classified to assess the spatio-temporal changing pattern of the forest reserve. the results showed different composition of vegetation, which include undisturbed forest, s econdary regrowth and farmlands. the study further revealed that in 1986, 2002 and 2017, undisturbed forest constituted 63.3%, 32.4% and 32.1% of the entire land area respectively, while secondary regrowth occupied 8.3% in 1986, 9.5% in 2002 and 15.6% in 2 017. the farmlands had erratic growth between 1986 and 2017. it was 16.9% in 1986, 22.1% in 2002 and 17.5% in 2017. the bare ground exhibited inconsistency in the coverage. in 1986 the areal extent was 11.5%, when it increased to 36% in 2002 and decreased to 31.9% in 2017. in conclusion, the study revealed the extent of forest depletion at akure forest reserve and it is therefore important that the residents, the governm ent and the researchers show major concern about some of the critical factors to human b eings that are responsible for forest depletion. keywords: landsat, deforestation, image classification, akure forest reserve, land use introduction establishment of forests began in nigeria in 1897 with the creation of woods and forests for the colony and protectorates of lagos, a year earlier, in 1896 (schoneveld, 2014). the first forest reserve was created in 1899 under the colonial master, which arose issues of land tenure (adeyoju, 1975). the colonial government’s initial interest in creating protected areas was to ensure a continuous supply of timbers and other forest resources to the indigenous industries. in the 1900s, the first ever protected area was olokemeji reserve and it commenced near ibadan under the western state then in 1956. having seen the benefits derived from the forest, this metamorphosed to the high demand for the establishment of more protected areas (onokerhoraye, 1985). spenceley (2015) gave an estimation of 200,000 protected areas in the world, which covered around 15% of the world’s land and around 2.8% of the oceans and nigeria has 960 constituted protected areas which covered a total land area of 10,752,702 hectares representing about 10% of the total land area of 997,936 hectares (oyebo, 2006). these protected areas were subdivided into six categories. it comprised of 1 strict nature reserve, 1 community forest, 23 game reserves, 925 forest reserves, 8 national parks, and 2 wild life sanctuary (fosa, 2000). forests are essential renewable natural resources that have a significant role in preserving environment and serving as home for all forms of life (singh et al., 2002; boyd and danson, 2005). the food and agriculture organization (fao) in 1989 pronounced it as home to 300 million people around the world and also contributed to 1.2 billion people living in extreme poverty with women accounting for 70%. fao (2001) and singh et al. (2006) described forest as a plant community where the predominant of trees and other woody vegetation with a tree canopy covered more than 10% and area of more than 0.5 ha. the forests of today have evolved over millions of years. it had been profoundly shaped drastically by swings between warm and cold climates all over the world fao (2012). the news of last great ice age is ended about 10,000 years ago leaving forests on nearly 6 billion hectares, about 45 percent of the earth’s land area. during the last 10,000 years, cycles of changing climate and temperature had continued to influence the world’s forests, while human activities had also increased (fao, 2012). fenning and gershenzon (2002) reported that thirty percent of the earth’s land surface area (3.9 billion hectares) forest covers had been depleted from the original forest cover estimated to be six billion hectares while fao (2010) put current forests cover at about 4 billion hectares, about 31 percent of the earth’s land surface; and over a period of 5,000 years, the cumulative loss of forest land worldwide is estimated at 1.8 billion hectares – an average net loss of 360,000 hectares per year (williams, 2002). these patterns also applied to other 2 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. developing countries in the tropics and sub-tropics. for instance, the east african region lost about 10% of its forest cover to deforestation between 1990 and 2000, with uganda recording the highest rate (fao, 2003). in the humid tropical rainforest region of cameroon, about 200,000 hectares of forest was reported to be degraded annually due to high rate of exploitation (fao, 2003). and always being an issue of disagreements that it was difficult to make a reliable estimate of the world total forest and local forests, since it depends on the different criteria used to define them then no accuracy measured or consensus in which forest to be measured currently. in nigeria, natural forest covered a total land area of 349,278 km2 or approximately 35% of the country’s total land mass of 997,936 km2 (nweze, 2002). but about 60% of the country’s forests disappeared between 1850 and 1960 (morakinyo, 1991). in 1980 alone, forest depleted from 14.9 million hectares to 10.1 million hectares and in 1990 to 1996, it further decreased geometrically to 9.5 million hectares (federal department of forestry, 1997). on the average, it decreased at the rate of 0.4 million hectares per year but the rate of reforestation was put at 0.032 million hectares per year. the forest reserve has also been facing the same effect of this predicament from onset. in ondo state, 107.36 km2 of forest in ore-township has been converted to casual land (adetayo, 2015). donald (2004) worked on the rich tropical rainforests in many parts of the humid tropics, and the forest disappearing has been attributed to logging and agricultural expansion activities. butler (2005) stated that nigeria has the world’s highest rate of deforestation of primary forests, with nest (1991) documented that at least about (30,000 ha) of forest and natural vegetation were lost annually in nigeria and this implied that nigeria has lost 55.7% of its primary forest to logging, subsistence agriculture, collection of fuel wood and other agents between 2000 and 2005 (fao, 2005). in an attempt to satisfy both local and international need for forest products and the continuous increase in rural population, forest resources exploitation in this ecosystem is carried out in uncontrolled and unsustainable manners (onyekwelu et al., 2010). fao (2005) listed nigeria as one of the developing countries with very high rate of deforestation and this rate was estimated to be 3% which was not usually consistent. all other woodlands, apart from the constituted areas are regarded as free areas (adekunle et al., 2013). both constituted areas and non-constituted areas are almost exhausted for being leading producer of cocoa and timber respectively (oke and odebiyi, 2007). however, deforestation had been a major concern for the ministries, government, private individuals, non-governmental organizations (ngos) and researchers. in an attempt to curb indiscriminate felling of trees or general destruction of forests, forest reserves were gazetted across the state. despite this, forest reserves continued to shrink in size and area due to pressure mounted from growing populations. in this study satellite images (landsat tm 1986, landsat 2002 etm+ and landsat 2017 oli_tirs) of 30m resolution had been classified to forest vegetal characteristics of akure forest reserve from optical remote sensors and spatial pattern changes were also assessed the in the forest reserve between 1986, 2002 and 2017. deforestation conceptual framework: concerning the deforestation in developing countries, an attempt is made to formulate an integrated theoretical framework of the deforestation and forest transition and sustainability theory among others (yaoqi, 2000). the forecasts and policy suggestions to be presented are argued to be relevant. to analyze deforestation, it is necessary to understand its different causes and sources and adopt a standard for dealing with menace. an approach can be devised to guide the process of identification and analysis of deforestation. a decision point approach was adopted to facilitate this process as shown in (fig. 1). the framework further fig.1 decision point approach for identification source and causes of deforestation gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. 3 addresses the identification and classification of different sources and causes of deforestation. it made it necessary to link the analysis to a methodology for the estimation of the extent of potentials of deforestation. the first step was to apportion the deforestation leakage to the different baseline drivers and agents, as they may change with time and space. for example, if the baseline driver was deforestation, but there are two key baseline agents, subsistence farmers and commercial cattle ranchers, the extent to which each contributes to potential leakage may differ over the project lifetime (louise et al., 2003). the study is therefore examining forest vegetation characteristics at akure forest reserve from optical remote sensing, assessing the spatial changes in forest between 1986 and 2017, and compare the efficiency of optical remote sensing and normalized difference vegetation index. the factors mapped include land conversion and illegal logging which actually led to the extent of the total area at present status, what are the major anthropogenic activities involved, how much was the levels of encroachment and what was resuscitate steps towards the forest. study area akure forest reserve is geographically located in a humid rainforest zone of akure south local government area of ondo state, nigeria (fig. 2). it lies between latitudes7o16′ and 7o18′ n of the equator and longitudes 5o 9′ and 5o11′e of the greenwich meridian. it was constituted as a reserve in 1936 and the total land area covered is 69.93 km2. politically, it lies in ondo state in southwestern nigeria and shares border with osun state in the northeast, surrounded by five local government areas in ondo state namely: ile oluji, oke-igbo, ifedore, akure south, idanre and ondo east. adetula (2002) estimated 11.73% (8.2 km2) cleared for cocoa farming and other food crops, fuwape et al. (2001) documented the gmelina arborea covered (721.40 m3 and nauclea diderrichii spp (265.18 m3) respectively, oke (2012) worked on family sterculiaceae including the species counted for 53% of the total tree canopies in the forest, adejoba et al. (2014) identified hard species as strombosi apustulata, celtismild breadi, myrianthus arborea, or khayasene galensis and triplochitons cleroxylon. key informants interviewed according to the work of owusu (2018) affirmed that the loss of vegetation in the city creates livability concerns relating to ecosystem functioning, temperature rise and air quality. he therefore recommended that decision makers should address three critical concerns of resilience, sustainability and livability. the relief pattern is low lying, elevation ranges from 216m to 504m and gently undulating in southern part while the northern part is hilly rock outcrops occurring at close intervals. the underlying rock is crystalline and gneiss. it is slightly neutral; ph of 6.7– 7.3 and sandy-loam in nature. the dry season lasts from november to march while the wet season commences from april and ends in october with the highest rainfall records between july and august (akinseye, 2010), average daily temperature ranges between 210c and 290c almost throughout the year (adejoba et al., 2014). the mean annual rainfall varies from 2000 mm in southern area to 1500 mm in northern area with relative humidity of 80–85% annually experienced in south-west (nimet, 2016). aponmu and owena yoruba speaking communities owned the forest, though, it also had minor settlements surrounding the forest. they include ipogun, kajola/ aponmu, kajola, ago petesi, akika camp, owena town, ibutitan/ilaro camp, elemo igbara oke camp and owena water new dam. fig. 2 overview of akure forest reserve data spatial coordinates of prominent settlements in the akure forest reserve (afr) were captured as points with garmin etrex20 global positioning system (gps) device. topographic map (1:250,000) was sourced from the office of surveyor-general of the federation (osgof), abuja. the map was scanned through a0 scanner. the map was georeferenced with grid coordinates on the map through arcgis 10.3 and it was used to exact boundary of akure forest reserve and other important features in the forest reserve such as, the road networks that are within the forest for accessibility was updated via open street map. the river network in the study area was extracted because the two major rivers flow through the forest forming the forest reserve boundary and the root means square error was 0.5 for the spatial accuracy. the survey plan (1:5000) was sourced from the ministry of natural resources, alagbaka, akure, ondo state. the plan was scanned using an a4 flatbed scanner. it was imported into the computer and georeferenced with grid coordinates on the survey plan using arcgis 10.3. boundary was also extracted which was more accurate than the one from topographical map and it was used for boundary extent and images subset as well. the existing topographical map and survey plan were referred as the base maps in the study. landsat, a u.s developed series of platforms operated by earth observation satellite company (eosat) are the most common satellite systems for large area data acquisition. the 4 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. satellites sensors offer broad area of coverage, and for instance thematic mapper (tm) sensor covers 165 x 180 km with temporal resolution of 16 days, six bands with spatial resolution of 30 m (blue, 0.45 to 0.52 µ m; green, 0.52 to 0.60 µm; red, 0.63 to 0.69 µm; near infrared, 0.76 to 0.90, µm; mid infrared, 1.55 to 1.75 µm; and mid infrared, 2.08 to 2.35 µm) and one band with spatial resolution of 120m (thermal infrared, 10.4 12.5 µm). landsat enhanced thematic mapper plus (etm+) sensor covers 170-183 km with temporal resolution of 16 days, bands 1-5 and 7 contain spatial resolution of 30meter. the resolution for band 8 (panchromatic) is 15 meters (blue, 0.45-0.52 µm; green, 0.520.60 µm; red, 0.63-0.69 µm; near infrared, 0.7-0.90, µm; shortwave infrared (swir) (1) 1.55-1.75 µm; thermal, 10.40-12.50 µm; shortwave infrared (swir) (2) 2.09-2.35 µm and panchromatic band has a spatial resolution of 15 meter (0.52-0.90 µm). landsat 8 operational land imager (oli) and thermal infrared sensor (tirs) sensor covers 170 x 183 km temporal resolution of 16 days. it consists of nine spectral bands with a spatial resolution of 30 meters, for bands 1 to 7 and 9. the ultra-blue band 1 is useful for coastal and aerosol studies. band 9 is useful for cirrus cloud detection. the resolution for band 8 (panchromatic) is 15 meters. thermal bands 10 and 11 are useful in providing more accurate surface temperatures, ultra blue (coastal/aerosol 0.435-0.451µm; blue 0.452-0.512µm; green 0.533-0.590 µm; red 0.636-0.673 µm; near infrared (nir) 0.851 0.879µm; shortwave infrared (swir) (1)1.566-1.651 30µm; shortwave infrared (swir) (2) 2.107-2.294µm; panchromatic 0.503-0.676 µm; cirrus 1.363-1.384 µm; thermal infrared (tirs) (1) 10.60-11.19 µm; and thermal infrared (tirs) (2) 11.50-12.51µm. (both systems are in sun synchronous orbits so the satellite passes over the same area of the earth at the same solar time in each temporal cycle. the landsat tm 1986, landsat 2002 etm+ and landsat 2017 oli-tirs of 30m resolution and each was captured in june. the land use/ cover classification systems were adopted for the study. the land use/cover product is classified into five land cover classes; undisturbed forest, farmland, secondary regrowth, bare ground and water body. the study used landsat data to carry out change evaluation of forest vegetation characteristics and assessed the spatial pattern changes in the forest reserve between 1986, 2002 and 2017. table 1 describes merely the secondary data with their parameters which include satellite data and existing data of topographical map and survey plan used. table 1 parameter of the datasets for the study s/ n data type acquisition date swath (km) path/ row spat. res. (m) 1 landsat tm 19/6/1986 185 190/ 55 30 2 landsat etm+ 19/6/2002 185 190/ 55 30 3 landsat oli/tirs 20/6/2017 185 190/ 55 30 4 topographical map 6/6/1986 1:250,000 5 survey plan 15/12/2009 1:5000 methodology the methodology was summarized in the workflow of the data processing (fig. 3). data analyses, compilation and raster statistics were generated in both erdas imagine and arcgis 10.3. statistical analysis and investigation of possible trends were carried in microsoft excel as well. pre-processing of satellite data was required and normalized difference vegetation index (ndvi) was also engaged and analyzed for the study. satellite data was sourced through path 190/row 055 and downloaded from global land cover facilities (glcf), united states geological survey (usgs) in digital format into the computer via earth explorer window and then it was imported into erdas imagine 9.2 version through classic viewer. fig. 3 workflow of data processing the images noise was filtered through radiometric enhancement as shown in (fig. 4). the visual image interpretation and digital image processing combined with aid of creating layer stacking from the images the useful landsat manual guide was used to produce natural colour for the satellite data and sub -map creation of raster data was done from the boundary extracted survey plan. the pre-processing of layerstacking were carried out intensively for proper accountability of ortho-rectification of the satellite images. the image was then processed in erdas imagine software. the satellite image of each band was stacked. then, from the stacked satellite image the study area image was extracted by masking in arcgis 10.3 software. supervised classification was used and where the user develops the spectral signatures of known categories to extract phenomena by assigning each pixel in the image to the cover type to which its signature is most comparable. it is of interesting to know that area of interest (aoi) which also known as training classes were used to represent a particular class. gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. 5 basically it follows the operational order of: defining of training sites, extraction of signatures and classification of the image (supervised classification) then during the supervised classification process, the entire signature editor was selected and it was used on the classification process. the pattern of land use type, ground truthing and personal experience were considered as the 3 major advantages to analyze the remotely sensed data. the classes were defined by the difference in their physical attribute and characteristics by considering the option of maximum of likelihood method which possessed the capability of taking care of similar features in the study area. the ground truthing was also employed by blowing up the image pixel and obtained the coordinates and pre-loaded these coordinate on the gps device for the verification of the features in the study area in (fig 5). fig. 5 area frame sampling of akure forest reserve rgb: 654 it was conducted based on area frame sampling where the basic unit referred as segment. it was carried out in early march 2017. a systematic random sampling method was adopted for collecting sample points of samples segment. systematic random sampling enabled the samples be distributed evenly to all parts of the study. the size of sample segment is 1 km by 1 km and sample size is 0.5 km by 0.5km. a total of 47 segments were selected and 71 sampling points were collected, where each sample has two samplings and it further enhanced the authentication of the forest and it was subdivided into equal portions. the second approach is to calculate of the normalized differenced vegetation index (ndvi). this index is the difference of the near infrared (nir) and the red band divided by their sum (ndvi = nir-red/nir+red) which usually revealed areas that have high reflectance in the near infrared. data post-processing which included checking pixel reliability and separability, producer, users, omission error, commission error and overall accuracy were also adopted for the analyses. accuracy assessment reflects the real difference between classification and the reference data from the mapper by considering the rows (classes as mapped) and columns (classes as found in the field) and this has become more important than ever (congalton, 1991). in our study the results of the percentage accuracy of the producers and users for each class names, reference total, classified total and number of pixels corrected and with their overall accuracy were described for 1986, 2002 and 2017. remotely-sensed spectral data is a continuous form of data where digital numbers (dn) represent the reflected energy in each band (spectral region). the focus of image classification is to assign each cell or picture element (pixel) of the satellite digital data into an appropriate thematic category in a process called "discrete classification." the most common data clustering algorithm used was maximum likelihood and other types of data clustering algorithms. the decision rules for the supervised classification process are multi-level:nonparametric and parametric. for parametric signatures, it comprises of: maximum likelihood, mahalanobis distance fig. 4 enhanced landsat imageries1986,2002 and 2017 rgb: 321, 753 and 654 6 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. and minimum distance. parametric rule was used and it defines classified pixels that fall into the overlap region where pixel is tested against the overlapping signatures only and whenever it reveals that neither of these signatures is parametric, then the pixel be given unclassified. but then, if only one of the signatures is parametric, then the pixel is automatically assigned to that signature's class. the maximum likelihood decision rule is based on the probability that a pixel belongs to a particular class. it assumes that these probabilities are equal for all classes, and that the input bands have normal distributions and it had capability of taken care of all similar phenomena. land use depictions become strong option to this study. it arranges human conceptualization of true picture of the reality i.e. how the view of reality usually being represented in a simplified manner that still satisfy the information requirement for study at hand without being distorted. here are the basic entities used in the land use classification schemes are described as follow: undisturbed forest describes deep dark green tree with which includes with other trees of similar spectral signatures and it is usually computed and represented in polygon; bare ground includes lands with exposed soil, sand or rocks, and never has more than 10% vegetated cover at any time of the year; secondary regrowth describes light green tree with spectral response; water body describes lakes, reservoirs, stream, rivers, and swamps and farmland describes as tree crops and enclaves found within the forest. therefore, the quality control of the pixels was verified on the land use and all were found above the average. the analyzed spatial change assessment was generated and it was used to compare the areas covered for the study. meanwhile, time series of ndvi generation was subjected to the health status of the forest and also taking the average index over the complete study area, by allowing the comparison between years to examine. the normalized difference vegetation index (ndvi) had been known for its capability of monitor the health of the vegetation. both red and near infrared bands was adopted for this analysis this model has been extensively used to monitor drought, monitor and predict agricultural products, assist in predicting hazard fire zone and map desert encroachment (lillesand et al., 2004). the model formula was given below mathematically by rouse et al. (1974). 𝑁𝐷𝑉𝐼 = 𝑃𝑁𝐼𝑅 − 𝑃𝑅𝐸𝐷 𝑃𝑁𝐼𝑅 + 𝑃𝑅𝐸𝐷 (1) pettorelli et al. (2005a) explained the concept behind ndvi that for vegetated surface, red (pred) and near infrared (pnir) wavelengths are characterized by high and low absorption respectively. the index output value range the greenness from -1 and 1 negative values shows the presence of cloud water and snow while zero values form basis for rock and bare soil, moderate values such as 0.2 to 0.3 represents the shrub and grassland while high values such as 0.6 to 1.0 indicate the temperate and tropical rainforest in accordance with work done by (lillesand, 2004). in 1986, it was revealed in figure 6 that -0.4 to 0.4 indicates the presence of water body, rock and the scattered tropical forest in the forest. in 2002, it revealed -0.4 to 0.08 which shows that the scattered tropical forests are no longer seen again as seen before. in 2017, it ranged from -0.4 to 0.3 which shows the presence of water, rock formation, tree canopies and the tropical forest recovered little from the shocked of consumers. the overall result indicated that there were moderate shrubs and grassland, fewer temperate and tropical rainforest in the reserve. fig 6 normalized difference vegetation index of 1986, 2002 and 2017 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. 7 results the entire study area covered 69.93 km2 which was tuned to about 7139.8 hectares of forest land. the undisturbed forest was characterized as deep dark green tree in 1986 represents the total area of 4520.7 hectares (63.3%) of the whole study area, bare ground covered, 818.1 hectare (11.5%), farmland occupied 1209.9 hectares (16.9%), secondary regrowth forest covered 590.9 hectares (8.3%) and water body as well covered the tune of 207.900 hectares which represents 2.9 % of the forest. these were so even before the forest was constituted as a reserve in 1936. in 2002, bare ground was increased by covering 2573 hectares represents (36 %) as against (11.5%) of 1986, farmland increased by1575.3 hectares (22.1%) as against 16.9%, secondary regrowth increased by 590.993 hectares (9.5%) against 8.3%, undisturbed forest decreased gradually to 2311.3 hectares (32.4%) as against 63.3% increased previously. in 2017, bare ground represented 2274.4 hectares (31.9%) reduced by 4.1% in five year of the study, the farmland also covered 1249.470 hectares (17.5%), undisturbed forest decreased further to 2289.900 hectares (32.1%), secondary regrowth covered 1118.070 hectares (15.6%), while water body covered 207.900 hectares (2.9 %) emerges openly due to human factors being seen all over places in table 2 and that summarized patterns of land use in details for 1986, 2002 and 2017. figure 7 quantified amount of alterations influenced by the humans. while making compare of 1986, 2002 and 2016 land use change, it were discovered that the deleption around obada,owena and ibutitan/ilaro camp induced by the influence of human factors due to direct access. vegetation was more seen in 1986 but unlike 2002 and 2017. water body was not also revealed in the data of 1986 and 2002 but there the indication of riparian forest was seen on satellite image. owena river that formed the bases of natural boundary of the forest was dredged for the purpose of dam construction. it was resulted into emergency of water body revealed on the image of 2017. figure 8 presents the proportion of land use categories of 1986, 2002 and 2017 in distinct multiple charts. it is vital to compare between green cover areas and areas are subjected to changes in proportions since it answered to when, how or table 2 compositions of land use of akure forest reserve in 1986, 2002 and 2017 land use classes landsat tm 1986 landsat etm+ 2002 % change 1986-2002 landsat oli 2017 % change 2002-2017 area [ha] area [%] area [ha] area [%] area [ha] area [%] undisturbed forest 4520.7 63.3 2311.3 32.4 -30.9 2289.9 32.1 -0.3 farmland 1209.9 16.9 1575.3 22.1 5.2 1249.4 17.5 -4.6 bare ground 818.1 11.5 2573.0 36 24.5 2274.4 31.9 -4.1 secondary regrowth 590.9 8.3 679.9 9.5 1.2 1118.0 15.6 6.1 waterbody 207.90 2.9 2.9 total 7139.8 100 7139.8 100 0 7139.8 100 0 fig. 7 patterns of land use in 1986, 2002 and 2017 8 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. why the forest had changed from time without numbers. in 1986, 63.3% of the area was considered as vegetated areas, this decreased to 32.4% in 2002, and it was almost half of undisturbed forest had been altered over a period of sixteen years which was hugged. in fifteen years later, it was reduced to 32.1%, the reduction accounted for variation of 0.3% in 2017 which was no pronounced as it were in 1986 to 2002. the reduction is not significant as results of interference by the concerned authority of the forest in 2017. farmland in 1986 was computed as 16.9%, it increased 22.1%, in 2002, in 2017, it was 17.5% which decreased by 4.6%. bare ground in 1986 was 11.5%, in 2002, it significantly inclined to 36%, in 2017, it was 31.9%, in 1986, secondary regrowth tends to increase from 8.3% 9.5% for the period of sixteen years and later increased to 15.6% in 2017. this increased showed that there was interference of the concerned authority along the line to improve the forest by reintroducing seedlings to the settlers found around the forest. at emergence of water body, it accounted for 2.9% of the total area of the study. the rate at which undisturbed forest reduced in forest between 1986 and 2002 was shown vividly in table 2. it decreased by about 3.1% per annum and reached the peak around the year 2002. by this year, the forest area had recorded roughly at about 30.9% of the forest that was left under undisturbed forest. between 2002 and 2017 the rate of vegetation reduction was close to negligible. it was as low as 0.3% which suggests that there were very little open forests to be altered and converted to other land uses. the farmland reduction in 2002 drastically as results of cocoa and banana plantations people around the forest had been practicing in the area. in 2017, also it shows that there was conversion of 4.6% which implies there conversion of more forest than in 1986, but slightly drops from the figures recorded in 2002. large conversion of forest into other land uses, including bare ground has significant implications, which could be best explained by its settlers round the forest. in 2002, it was 36% of the total forest which had doubled up of what actually recorded in 1986. in 2017, the increased drop by 4.1% in fifteen years later. secondary regrowth tends to improve by the initiate being put place by concerned authority for the period of last sixteen years. the water body emerges due to alteration of the river that formed the boundary for the forest. the study also focuses on the option of integrated ground truthing measured to authenticate the reality on the ground. accuracy assessment reflects the real difference between classification and the reference data from the mapper by considering the rows (classes as mapped) and columns (classes as found in the field) and these had become more important than ever as it shown in tables 3, 4 and 5. reference data believes to be accurate and it reflects the true land use. it had a sources which include, ground truth, higher resolution satellite images and maps derived from aerial photo interpretation while number correct denote software correction after classification. the overall accuracy of the classified image compares how each of the pixels classified versus the actual land cover conditions obtained from their corresponding ground truth data and it considers all off-diagonals together as classification failures. table 3 accuracy assessment pattern of 1986 c la ss n a m e r e fe re n c e t o ta l c la ss if ie d t o ta l n u m b e r c o rr e c t p ro d u c e rs a c c u ra c y u se rs a c c u ra c y undisturbed forest 173 194 159 91.91% 81.96% farmland 54 38 37 68.52% 97.37% bare ground 44 30 28 63.64% 93.33% secondary regrowth 26 14 13 50.00% 92.86% total 297 276 237 *overall classification accuracy (86.72%) * overall kappa statistics (0.804) table 4 accuracy assessment pattern of 2002 c la ss n a m e r e fe re n c e t o ta l c la ss if ie d t o ta l n u m b e r c o rr e c t p ro d u c e rs a c c u ra c y u se rs a c c u ra c y undisturbed forest 18 39 16 88.89% 41.03% farmland 21 10 6 28.57% 60.00% bare ground 65 63 51 78.46% 80.95% secondary regrowth 30 12 10 33.33% 83.33% total 134 124 83 * overall classification accuracy (77.34%) *overall kappa statistics (0.675) fig 8 proportion of land use categories in 1986, 2002, and 2017 0 1000 2000 3000 4000 5000 undisturbed forest farmland bare ground secondary regrowth water body a r e a i n l a n d u se c a te g o r ie s area hectares (1986) area hectares (2002) area hectares (2016) gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. 9 table 5 accuracy assessment pattern of 2017 c la ss n a m e r e fe re n c e t o ta l c la ss if ie d t o ta l n u m b e r c o rr e c t p ro d u c e rs a c c u ra c y u se rs a c c u ra c y undisturbed forest 54 45 40 74.07% 88.89% farmland 37 25 21 56.76% 84.00% bare ground 67 46 36 53.73% 78.26% secondary regrowth 15 15 11 73.33% 73.33% water 9 2 2 22.22% 100.00% total 182 133 110 *overall classification accuracy (71.05%) *overall kappa statistics (0.675) this further expressed some of human and environment factors which have contributed to the forest depletion. the factors concern includes the rising of logging, the frequency and severity of water over bank which sometimes falls most of tall trees because it was rivers the formed the natural boundary of the forest, cattle herders and fire. although, these were views being seen during the data acquisition and they merely facts to reckon with table 6 presents the trend of various land use for 1986, 2002 and 2017 as it shown below and it was explained further by displaying the rate change (%) in the two investigated periods (1986-2002 and 2002-2017). table 6 rate change (%) in the two investigated periods (19862002 and 2002-2017) land use rate of change (%) 1986-2002 rate of change (%) 2002-2017 undisturbed forest -30.9 -0.3 farmland +5.2 -4.6 bare ground secondary regrowth +24.5 +1.2 -4.1 +6.1 water body +2.9 discussion the important concepts of forest cannot be overemphasized because it was spatially distributed across the surface of the earth and by offering the potential values to the dynamism of local, regional and global ecosystem processes. it needs to be protected, monitored for conservation and sustainable management at all time. mostly, forests are important globally for provision of fibers to meet human needs, from local uses such as cooking fuel through to industrial utilization for construction materials. although, land use has been extensively analyzed by the researchers in the past through the aid of satellite data and they had been achieved greatly. in this study, it has been proven, that the supervised classification of multi temporal satellite images were more effective tool to quantify and detect changes/alteration of environment which were shown in figure 7. however, it indicated that bare ground, farmland and secondary regrowth in the area have increased tremendously, to possibly support population growth of the surrounding settlements or influx of loggers often coming from the cities. with this evidence, one can actually submit that most of undisturbed forest had been converted to bare ground and farmland since it is obvious that undisturbed forest was at pace of reduction yearly and it was equally shown on the image while the secondary regrowth is gaining its popular expansion as well as others. ndvi is useful for checking the health of the reserve and to compliment the various categories of the spatial change patterns derived from the landsat. additionally, it is also important to adopt ground truthing approach as it was shown in figure 5 to authenticate the exact feature on the ground as it is against the final classification for clarification and this was a little bit difficult but it was later successful. it was extensively discussed in tables 2, 3and 4 describe the accuracy of classified image which had been proven important and that serves as of authenticity for any image used (aronoff, 1958). the post classification required since the final accuracy of image depends on the accuracy of the independently classified images (yuan et al., 2005). this was done by using the accuracy assessment module in erdas imagine. the results in table 6 tend more than enough to permit its use for further analysis. another way of identifying change within the study area is by using the kappa index of agreement (kia) which ranges from -1 to 1 and study findings were 0.8047 (in 1986 image), 0.6753(in 2002 image) and 0.6138 (in 2017 image) and the results supported the statement attributed by congalton and green (1999) that overall change occurred by chance, then k equals zero (k= 0). that means changes have taken place in both classified data. most often conversion of the reserve to farmland had improved their quality life and behavioural pattern of the dwellers in the settlements by making their ends from the forest because they have known for cocoa farming as their major occupation especially those dwellers in the suburb. and to the authority, it contributes to the sustainable development of ecosystems and provision of ecological range and social benefits had been deeply threatened due to the quest of getting resources out of the forest. it is expected that the authority concerns control the abundance and biodiversity of the forest and take the responsibility by ensure protection and others. conclusion forest vegetation characteristics and spatial pattern changes in the akure forest reserve between 1986, 2002 and 2017 were successfully observed by obtaining landsat images. the data analysis shows that forest has lost almost all the vegetation cover. it’s just leaving about 32.1% of undisturbed forest as at 2017 while other land uses are increased yearly. the critical part of the reserve loss occurred between 1986 and 2002. these indicate that the spatial distribution pattern of bare ground had increased geometrically due to interferences of the settlers that surrounded the reserve and farmland also increased due the conversion of forest to cocoa plantations. consequently, the reserve had been threatened due to anthropogenic activities of man while the vegetation of secondary 10 gbiri and adeoye 2019 / journal of environmental geography 12 (1–2), 1–11. regrowth, farmland, and bare ground began to increase and the vegetation being known within the reserve which characterized by hard species noticed no more. interestingly, the period was characterized by conversions including farmland and among others. this study recommends that for akure forest authority to address problems relating to conversions of forest there is the need to take critical look at the forest policies plans and its implementation which can provide quick answered to some of intermediate and underlay causes of forest conversion. the past three decades saw that there is a shift to revitalize some of our forest from the hands of loggers and others. this pattern had been helpful and it must be focused on it if forest in akure needs sustainability. however, it’s erroneous difficult in achieving these recommendations in conceptual frame work due to changes in policy most often. references adejoba, o., kleine m., taboada t. 2014. reducing deforestation and forest degradation and enhancing environmental services from forests (reddes), with support from the international tropical timber organization (itto), iufro-spdc and fornessa, akure, ondo, nigeria. online available at: https://www.iufro.org/download/file/18240/5656/fornessa_ factsheet_nigeria_final_pdf/ adekunle, v.a.j., olagoke, a.o., ogundare, l.f. 2013. logging 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(eds.) world forests from deforestation to transition, 2000. kluwer academic publishers, dordrecht, china, 41–65. yuan, f., sawaya, k. e., loeffelholz, b. c., bauer, m. e. 2005. land cover classification and change analysis of the twin cities (minnesota) metropolitan area by multitemporal landsat remote sensing. remote sensing of environment 98 (2-3), 317–328. doi: 10.1016/j.rse.2005.08.006 introduction study area data methodology results discussion conclusion references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. i. no. 3-4. pp. 21-26 small format aerial photography – remote sensing data acquisition for environmental analysis tobak, z. 1 – szatmári, j. 1 – van leeuwen, b. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract since february 2008, an advanced system has been developed to acquire digital images in the visible to near infrared wavelengths. using this system, it is possible to acquire data for a large variety of applications. the core of the system consists of a duncantech ms3100 cir (color-infrared) multispectral camera. the main advantages of the system are its affordability and flexibility; within an hour the system can be deployed against very competitive costs. in several steps, using arcgis, python and avenue scripts, the raw data is semi-automatically processed into geo-referenced mosaics. this paper presents the parts of the system, the image processing workflow and several potential applications of the images. keywords: small format aerial photography, data acquisition system, image processing, python introduction acquiring aerial photographs and their digital analysis are traditionally long and expensive processes (warner w. s. et al. 1996). as digital cameras, computers and gps receivers became available at lower price ranges, the amount of time and cost needed for the acquisition process and the analysis is gradually reduced, which highly increases the operativity of the system (licskó b. – ditzendy a. 2003, bakó g. 2010). earlier the colour infrared small format digital cameras were mainly used for surface measurements (warner w.s. et al. 1996). the near infrared spectrum is mainly used in vegetation monitoring but it also promotes the identification of the areas covered with water (rakonczai j. et al. 2003, tucker d. et al. 2005). the advantage of using small format aerial photography the development of a small format aerial photography system that is able to take colour infrared (cir) aerial photographs was started at the spring of 2008 by the department of physical geography and geoinfomatics at the university of szeged. out of the numerous advantages of the system, its cost efficiency and its operativity can be highlighted. beyond the price of the digital camera, that was a single investment of the department, only the costs of the flights and the wages of the human resources participating in the processing have to be paid. the fact that the system is easy to operate becomes particularly important in projects that investigate quickly changing phenomena (bakó g. 2010). inland excess water, as a temporal water surface – depending on the weather conditions – can evolve rather quickly, but its extension can diminish relatively fast as well. to discover a mapping methodology for excess water and to be able to model its development, it is inevitable to know the actual extent of the area covered with water (licskó b. – ditzendy a. 2003). the country-wide aerial photography campaigns carried out every 5 years provide photographs with inappropriate time resolution. by using our small format aerial photography system, photographs can be taken at any time at any frequency, which provides basic data for further analyses. not only the time resolution, but the spatial and spectral resolution of the photographs adjusts better to the needs of the research. the size of the smallest object (pixel) on the surface that can be mapped falls within the sub-meter interval and it can be altered depending on the altitude of the flight. this harmonizes well with the size range of the examined excess water coverage. in comparison: while the satellite images provide only 4, 10 or 30-meter resolution data, the country-wide aerial photography data provides 1-meter resolution. our camera is able to record in 3 spectral bands of the electromagnetic spectrum: in the visible green (g), the red (r) and the near infrared (nir) bands. out of these, the near infrared band is of particular importance, as in this band the water surfaces nearly completely absorb the incoming radiation and thus they appear as dark, black territories, which are easy to detect both visually and also by using image-processing techniques. by using the red (r) and near infrared (nir) spectra together, the vegetation can be differentiated. on the other hand, the traditional aerial photographs – provided by the country-wide aerial photography, for example – cover only the spectrum of visible light and thus they provide much less spectral information regarding the excess water areas. introducing the recording system a duncantech ms 100 cir (colour infrared) digital multispectral camera forms the basis of the acquisition system. additional components are an attached data storage computer – equipped with a framegrabber card – 22 tobak z. – szatmári j. – van leeuwen b. joeg i/3-4 and gps receivers (mobile mapper ce and garmin gpsmap 296) that help the navigation and also record the flight path (fig. 1). the duncantech ms3100 digital multispectral camera contains 3 single ccd sensors (fig. 2). the sensors detect the photons of the red (r), green (g) and near infrared (nearir) spectra separately, depending on the prism (which splits the light) in front of the sensors (table 1). the 3 sensors can be programmed separately, which means that not only their gain but also the applied integrating time can be adjusted to the needs of the users. this way it is possible to strengthen the ir spectrum – which is used to take photographs of vegetation and water surfaces – taking advantage of their special nir reflectance. fig. 2 sensitivity of the green, red and near-infrared sensors the sensors are built up of 1392x1040 pixels, the physical size of each is 4.65x4.65 micron. the radiometric resolution of the detectors is 10 bit therefore they are able to differentiate maximally between 2 10 , i.e. 1024 intensity values. this way relatively low reflectance differences between recorded object can be identified. the ground resolution of the data always depends on the optics and flight height. using the high-speed tokina at-x 17 af pro objective at a flight altitude of 2000 m the spatial resolution is 62 cm. table 1 recording spectrum of the cir camera cir configuration (nm) band range center width blue green 530 – 570 550 40 red 640 – 680 660 40 nir 768 – 832 800 65 a mini computer with a national instruments imaq 1428 type framegrabber pci card was used to store the photographs. the transportation of the data from the camera to the framegrabber is done through camera link connection, in three channels, each of which transports 10 bit data to the framegrabber. the further settings of the data recording – the frequency of exposure, the name and the place of the saved photos, the integration time and the sensitivity of the sensors – happens at the time of acquisition with the dt control software supplied with the camera. during the acquisition, navigation was carried out by a garmin gpsmap 296 aviation gps device following the planned flight. the actual flight path was recorded with a thales mobil mapper ce type gps receiver. while the digiterra explorer mobile gis software running on the windows ce based device helps the naviga fig. 1 hardware elements of the recording system (left) and the cessna 127 airplane with the cir camera fixed into its luggage space (right) joeg i/3-4 small format aerial photography – remote sensing data acquisition for environmental analysis 23 tion, the gps status application of the thales records the gps data in nmea format. subsequent processing of the gps data provides one meter accuracy flight track. to carry out the flight a cesna 172 type airplane was used, which is the property of the partner company. in the four-seater airplane the person sitting next to the pilot directs the navigation and operates the camera. while the camera is in a construction fixed to the side of the plane, the data recording and energy supplier components – the batteries and the inverter – are in the luggage space of the plane. the hardware elements of the system presented above cost nearly 13,000 euro. the cost of operation is about 250 euro for an hour long flight, which of course changes depending on the distance of the destination and the shape of the acquisition area. as our point of departure is the szeged airport, our primary destination is the southern part of the great hungarian plain. nevertheless the flexibility of our system allows its installation into any airplane that has got a door on its luggage space. flight plan while preparing the flight plan, it has to be decided in which way to cover the area to be recorded. not only the planned flight paths have to be recorded, but also the necessary time intervals between the exposures. to do this not only the speed of the flight and the size of the area covered by a single photo – in case of a fixed objective, the latter depends only on the altitude of the flight – has to be known, but also the distance between the photos (b) and the distance between the rows of photos (d) have to be defined. to facilitate later processing, the photos have to overlap each other by a minimum of 50% in the flight direction by 20-30% on adjacent flightpaths. taking these requirements into consideration, on a flight altitude of 2000 m, at the speed of 150 km/h the frequency of exposure is 1 photo/ 4 seconds and the distance of the neighbouring paths – in case the camera is fixed perpendicular to the flight direction – is 600 meters (fig. 3). fig. 3 a part of the recorded area with the planned and the actual flight paths, some sample images and characteristic parameters our inland excess water project had 3 sample areas (fig. 4), the total extension of which was 69.7 km 2 . out of these sample areas area i (tápairét) and area ii (batida) was recorded two times during the excess water period of spring 2010: on 24th march 2010 and on 9th june 2010. the recording was carried out based on the same flight path on both occasions. the 10 lines of flight, the nearly 100 cir images captured at each line, resulted in 1804 (895+909) images by the end of the second day. acquisitions have already been carried out for previous projects of the department and for external partners as well. in the course of these projects approximately an area of 1000 km 2 was recorded (tobak z. et al. 2008, kitka g. et al. 2010). for urban ecology research high spatial resolution – 50 cm pixel size – colour infrared (cir) data has been acquired for the total area of szeged (van leeuwen b. et al. 2009). 24 tobak z. – szatmári j. – van leeuwen b. joeg i/3-4 fig. 4 study areas covered with excess water and their surroundings with flightlines and the footprints of the images image processing during the preparation of the aerial photography, the flight and the processing of the raw data, different types of software had to be used. all through the work these software were customized to our needs and therefore the processing of the numerous photos could be made more automatic. during the preparation of the flight plan, the flight altitude was determined on the basis of the size and the shape of the area under survey and the desired resolution. having known the image sizes calculated from the altitude of the flight, the flight paths were determined. it is practical to orientate the lines in north-south or eastwest directions, although it is possible to rotate the images in any directions at any angles by the processing software. the planned lines were loaded in digiterra explorer in shape file format based on the hungarian national projection (eov). the image exposure can be controlled and its parameters can be set in real time during the flight. the data logger and the control software of the camera allow the modification of gain and the integration time. this makes the adaptation to the different light conditions possible. new series of images were created for each line of flight for which separate log files, containing the parameters of the camera and the exact time of exposure, were generated by the program. the images were recorded in three-band tiff files with 8-bit colour depth per band. in the first step of processing the x, y and z coordinates and the time data of the flight were extracted from the nmea file recorded every second by the gps. then based on these records a dbase table was generated. the time field of the table is joined (table join) with the log file of the camera thus the records of the table are joined with the images. with this operation real eov coordinates (x, y) were assigned to the central point of each image. in the next step these coordinates – and the spatial resolution – were used for the generation of the so-called world files. world files are simple ascii text formats, with which geographical coordinates can be assigned to jpeg and tiff files. in this way, using the coordinates recorded by the gps, geo-referenced images can be made from our images quickly and automatically. only in case of image rotation angles of 0 or 180 degrees is the application of the world files an effective method, therefore the flight directions were chosen in a way to make this possible. the generation of the .tfw world files connected to the tiffs requiring a rotation angle of 0 or 180 degrees was carried out with avenue script in arcview 3.2 software. in case of a different rotation angle the arcgis rotate tool was also used in a python script besides the world files. by means of the world files, a rough geometric correction was attained, the accuracy of which was better than 150-200 m, depending on the circumstances of the flight. in the next step the aim was to create an orthophoto mosaic of the whole studied area by the assembling and geo-correction of the single images. during the preparation of this process the tiff with world file was converted to img format by another python script. in the erdas imagine image-processing software tie points between the images of the block (image series) were automatically generated, and after their filtering the block was transformed to eov. a single, coherent image file was made from the individual images by mosaicing. fig. 5 summarizes the image processing workflow and demonstrates the data and operations used, the applied gis and image processing technologies, and different types of software. application of processed images the geometrically corrected cir images can be used in a wide range of studies. the common characteristic of these studies is that they require high spatial and temporal resolution and visible as well as near infrared spectral information. all of the above-mentioned requirements are of major importance during the exact delineation of the areas covered with inland excess water. in the classification procedure based on the artificial neural network (ann) under development in our department these images are the most important input data besides a high resolution joeg i/3-4 small format aerial photography – remote sensing data acquisition for environmental analysis 25 digital elevation model. the images supplied by the three bands are used as separate input layers both in the training and the simulation phases. besides the above-mentioned, ann-based, method visual information can also be interpreted by the conventional image analyzing methods. during the mapping of sources of pollution harmful to the environment – for example, illegal landfills, water reservoirs etc. – high spatial resolution and operativity are key issues (mucsi l. et al. 2004, szatmári j. et al. 2008). a gis database can be created from the different type of contaminating objects identified on the basis of the images (warner w. s. 1994, tobak z. et al. 2008, kitka g. et al. 2010). the red and near infrared bands of the sensor are well applicable for the monitoring of vegetation. these ranges of the electromagnetic spectrum are used for most of the vegetation indices. the estimation of the amount of biomass and chlorophyll, the separation of different forest types and the assessment of vegetation health are research topics for which good quality data can be provided (ladányi zs. et al. 2011). the monitoring of vegetation can be carried out in the urban environment as well. the remote sensing analysis of the complex and heterogeneous urban surfaces, with adequate spatial accuracy, can only be carried out if the geometric resolution is high. however, the spectral information content of the colour infrared images is narrow compared to the hyperspectral data. by their combination and by the development of multi-level classification methods, the advantages of both can be exploited. future opportunities, challenges our system – in its present state – is not suitable to completely replace the traditional methods of aerial photography. it does not contain inertial or other spatial reference system therefore there is no possibility to eliminate errors arising from the irregular movements of the airplane. positional errors depending on the weather conditions can partially be corrected by automatic switching point measurement. conversion of the energy values measured by the sensor (dn) to surface reflectance values would need further developments. field reference samples should be used for this during acquisition. the differences between the histograms of the images can be corrected by histogram matching. both hardware and software developments are needed in the future. for greater spatial coverage and thus more cost-effective recording, the replacement of the small-format camera (1392x1040 pixels) to a medium-format one (7220x5410 pixels) is among our plans. the expansion of the gps measurements with an inertial measurement unit (imu) is planned for faster and more accurate geometric correction. the self-made programs carrying out automatic processing also need further development by which the time elapsed between the image fig. 5 flow diagram of image processing from the raw images to the image mosaic 26 tobak z. – szatmári j. – van leeuwen b. joeg i/3-4 exposure and the production of processed – and even analyzed – images can be reduced. during the developments the targets set at the creation of the system are kept in mind. although the value of the entire system increases due to financial investments, the costs of operation and processing are kept on a cost-effective level. in addition, operativity, which is the main advantage of the system, remains and is further improved. acknowledgement the research was supported by the project “development of an belvíz-info system” (economic operative program: gop 1.1.1 08 / 1 -2008 – 0025). the deployment of the system was supported by the hungarian scientific research fund (otka t048903). references bakó g. 2010. igen nagyfelbontású légifelvétel-mozaikok készítése kisés középformátumú digitális fényképezőgépekkel. geodézia és kartográfia 62/6: 21-29 kitka g. szatmári j. mucsi l. tobak z. van leeuwen b. 2010. digitális légifelvételek alkalmazása a környezetvédelmi ellenőrzési folyamatokban. „térinformatikai konferencia és szakkiállítás. az elmélet és gyakorlat találkozása.” debrecen. 430-431 ladányi zs. – rakonczai j. – van leeuwen b. 2011. evaluation of precipitation-vegetation interaction on a climate-sensitive landscape using vegetation indices. journal of applied remote sensing, 5, 053519, doi:10.1117/ 1.3576115 licskó b. ditzendy a. 2003. az 1999-2000. évi belvizek légi felmérésének tapasztalatai. in: szlávik l. (ed.) vízügyi közlemények különszám iv. kötet: elemző és módszertani tanulmányok az 1998-2001. évi árés belvizekről. budapest: vituki. 305-315 van leeuwen b. – szatmári j. – tobak z. – német cs. – hauberger g. 2009. opportunities for the generation of high resolution digital elevation models based on small format aerial photography. hundem 2009 konferencia, miskolc mucsi l. kiss r. szatmári j. bódis k. kántor z. dabis g. dzsupin m. 2004. felszín alatti vezetékek környezetszennyező hatásainak felmérése távérzékeléses technológiával. geodézia és kartográfia 56/4: 3-8 rakonczai j. csató sz. mucsi l. kovács f. szatmári j. 2003. az 1999. és 2000. évi alföldi belvízelöntések kiértékelésének gyakorlati tapasztalatai. in: szlávik l. (ed.) vízügyi közlemények különszám iv. kötet: elemző és módszertani tanulmányok az 1998-2001. évi árés belvizekről. budapest: vituki. 317-336 szatmári j. tobak z. van leeuwen b. olasz a. dolleschall j. 2008. an effective and low-cost method to detect environmental contaminations: the promise of cir small format aerial photography (sfap). xii. geomatematikai szimpózium, mórahalom tobak z. kitka g. szatmári j. van leeuwen b. mucsi l. 2008. kisgépes, kisformátumú cir légifelvételek készítése, feldolgozása és alkalmazása környezeti vizsgálatokban. iv. magyar földrajzi konferencia, debrecen tucker d. chavez p. bogle r. 2005. rapid response low cost airborne digital imaging system. in: proc. of land remote sensing science fair, reston, virginia warner w. s. 1994. evaluating a low-cost, non-metric aerial mapping system for waste site investigators. photogrammetric engineering and remote sensing 60: 983988 warner w. s. graham r. read r. e. 1996. small format aerial photography. caithness: whittles publishing. 370 http://www.geo.u-szeged.hu/pub/pdf_ml/60-1.pdf investigation of tree stands of public spaces in szeged journal of environmental geography journal of environmental geography 8 (3–4), 33–39. doi: 10.1515/jengeo-2015-0010 issn: 2060-467x investigation of tree stands of public spaces in szeged ágnes takács*, márton kiss, eszter tanács, levente varga, ágnes gulyás department of climatology and landscape ecology, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: takacsagi@geo.u-szeged.hu research article, received 10 september 2015, accepted 1 november 2015 abstract in urban areas vegetation (especially woody vegetation) is of utmost importance, since it affects the ecological conditions of the city. urban trees play an important role in improving urban climate both at the local (city, district) and the micro-level (e.g. in public squares). establishing and maintaining advanced and detailed information systems necessary for the management of urban tree stands is an important task of environmental and climate-conscious city management. despite that, few of the hungarian municipalities have a regularly updated tree database. the city of szeged started efficient green space management in autumn 2013, when we started the creation of a detailed and up-to-date tree register for the public areas, which has been continuously expanded ever since. the survey of the present study covers the period of the growing season, from late spring to early autumn of 2013. all the trees are included in the survey and quite a number of data are recorded for each individual (e.g. species, age, size parameters, exact location, health status, etc.). the recorded data are paper-based, however they are included in a gis-based green space inventory software, greenformatic, where coordinates are associated to each object, while information on the state of the tree, its location and handling can be found in the attribute table. the trees included are mostly concentrated in the inner city of szeged, but the surveys will gradually cover ever larger areas of the city. the results highlight the fact that the structural attributes of the different species’ populations are formed by the integrated effect of the species’ urban tolerance and planting policies of the past decades. the current database already allows highly complex analysis, which contributes to the well-being of city residents. keywords: urban tree, green space management, tree database, greenformatic introduction tree stands have many positive effects on the ecological status of a city, its population's health and well -being, making the urban built environment more liveable. one of the most noticeable direct effects is changing the microclimatic conditions (andrade and vieira, 2007; bowler et al., 2010). during the active period of the growing season the daytime near-surface air temperature has been proved to be lower under the trees than above the free surface (lin and lin, 2010). this is primarily due to the canopy reducing the amount of radiation energy from the surface, as it reflects a part of it and absorbs another part although the extent of this effect depends on the season and the time of day (shashua-bar et al., 2011; konarska et al., 2013). this directly causes a decrease in temperature, while on the other hand it has an even more significant impact on human comfort, because it results in further physiological (heat) stress reduction, which is well detectable using different human comfort indices (égerházi et al., 2013). in areas planted with trees a much larger amount of water leaves to the air through evapotranspiration than either in grasslands or built-up areas. this increases humidity, which indirectly contributes to the development of lower temperatures under the trees and has a generally beneficial effect on human comfort, especially during heat waves (zhang et al., 2013). surface roughness increased by the presence of woody vegetation decreases the speed of nearsurface air movement, which can have both positive and negative implications. in winter, it can lead to significant heating-related energy savings (loehrlein, 2014). an important element of improving air quality is the absorption of air pollutants (e.g. ozone, nitrogen, sulphurdioxide, settling dust, etc.) the actual quantity depending on the amount of leaf surface. during photosynthesis trees use a substantial amount of co2 (extracting it from the air), one of the most important greenhouse gases (nowak et al., 2006). except for the latter, all those listed here have an indirect or direct impact on human health, either through human respiratory diseases or through otherwise affecting comfort. a very important ecosystem service of urban tree stands is the massive interception of precipitation on the leaf surface, a part of which evaporates directly, while the rest is slowly conveyed towards the ground, making infiltration easier, and significantly reducing the size of flash floods following extreme precipitation events (to an extent depending on the size and state of the stand). the water trapped in this way does not burden the sewage system at the time, but seeps into the soil gradually and thus more efficiently. this in turn improves the quality of otherwise poor urban soils (day and dickinson, 2008). 34 takács et al. (2015) creating and maintaining a green surface property cadastre is a statutory obligation for municipalities in hungary; woody vegetation represents a substantial part of this. however, the property value in this case is much more than just the value of wood. the pollutant and carbon sequestration, the reduction in runoff, the energy savings resulting from the shading of buildings are relatively easily expressible in monetary terms. defining the monetary value of much more abstract concepts such as the reduction of thermal comfort, the aesthetic and / or cultural value, the mental and physical regeneration effect the further benefits of well-maintained green areas and tree stands is much more difficult, however without doubt these also should be given some consideration. it makes monetary evaluation particularly difficult that the idea of a property gaining value over time instead of losing it is quite foreign to traditional economic thinking (mcpherson, 2003). study area szeged is situated in the south-eastern part of hungary (46°n, 20°e; 78-85 m above sea level), in the lower-tiszavalley, at the confluence of the rivers tisza and maros. according to péczely’s climatic classification (péczely, 1976) the great hungarian plain is characterised with a dry-warm continental climate, therefore in summer heat is typical and drought susceptibility is high in the szeged area. the annual sunshine duration is high and air humidity is typically low. winter snow cover is rare and the amount of snow is also low. szeged is the biggest city of the southern great plain region with an area of 281 km2 and a population of about 170 000 (fig. 1). due to its size, the city of szeged has easily detectable climatic effects on the local scale. the most apparent phenomenon is the formation of a so-called urban heat island as a result of artificial surfaces, which is most pronounced a few hours after sunset. in szeged the added heat from the heat island is on average 2-3°c, but in calm, anticyclonic periods it may reach up to 6-8°c (balázs et al., 2009). this (along with many other climatic effects) significantly affects the life chances of urban vegetation. it may therefore be useful if vegetation studies are supplemented with a climatological perspective, and vice versa, the climate-modifying effects of the vegetation are investigated. methods in order for a city to have an efficient green space management, which is also sustainable in the long term, a detailed, up-to-date database is necessary. to this end, in 2012 the department of climatology and landscape ecology of the university of szeged (in collaboration with the environmental management office of szeged) started to set up such a detailed tree register which helps the performance of operational tasks and maintenance while also provides an opportunity for the scientific examination of the urban ecological role of trees (e.g. complex ecosystem services evaluation). the data-recording fig. 1 tree alleys and squares recorded by the end of november 2013 investigation of tree stands of public spaces in szeged 35 during the field surveys was paper-based, with a high demand on time and human resources; university students were heavily involved in the work. the ideal period for the survey is from late spring to early autumn, namely the growing season, when the foliage has fully developed and autumn defoliation has not yet started. some parameters, such as the exact extent of the canopy or the health status of individuals can only be established with reasonable accuracy in this period. all the trees or shrubs with a dbh (diameter at breast height) over 5 cm are included in the survey and quite a number of data are recorded for each individual (e.g. species, age, size parameters, exact location, health status, etc.). photos are also taken of each tree and added to the database. additional data are related to the surroundings of the tree such as the size of the planting space, the nature of a protection measure or nearby damaging factors. health data contain information on injury and lesions detected on the root system, the trunk or the canopy, as well as other anomalies included as comments. based on the data recorded separately for the tree parts, an assessment of the whole tree’s health status is provided on a 5-point scale. the person recording the experienced damage can also make management proposals and include them in the database. in order to get more accurate scientific analysis some extra parameters are also recorded for each individual, which so far have not featured in such registers. these include for example the proportion of dried-out crown parts, the proportion of missing or truncated parts (as a percentage) and the degree of light availability. these enable more realistic calculations of tree volume and leaf area serving as input for pollutant absorption and carbon-sequestration calculations. thus regulatory ecosystem services can be evaluated more precisely (takács et al., 2014). in order to record and store spatial data a gis is necessary, since visualization and spatial analysis are part of the complex requirements of users (both managers and scientific experts). the greenformatic geospatial information software, is a targeted gis-based green space inventory software developed in hungary. coordinates are associated to each object, while information on the state of the tree, its location and handling can be found in the attribute table. this primarily serves to directly make users' everyday work easier. the results shown in the present work were derived from the data of over 5000 tree individuals recorded until november 2013 (see the extent of the area on fig. 1.). as shown on the map in figure 1, the database assembled by that date mostly represents the densely built-up areas of the inner city, within the great boulevard (nagykörút). results the tree population in the register recorded by november 2013 contains 5197 objects, the tree individuals belong to 110 species and 4 categories: stumps, empty planting spaces, former planting spaces and dried-out trees. the city is quite species-rich, however approximately 60% of the individuals belong to the 10 dominant species (table 1). there are 48 species with less than 5 individuals in the database. almost half of the recorded individuals belong to species non-native in hungary (fig. 2.). of these, sophora japonica, celtis occidentalis and koelreuteria paniculata are present in highest numbers (over 200 individuals each). of native species, different species of linden trees (tilia sp.) are most frequent (1321 individuals). fig. 2 the proportion of native and non-native species (miscellaneous: e.g. dried-out tree, removed planting space, unidentified species) table 1 the most common tree species in szeged within the surveyed areas tree species number of individuals % littleleaf linden tilia cordata 634 12.2% pagoda tree sophora japonica 542 10.4% common hackberry celtis occidentalis 472 9.1% silver linden tilia tomentosa 458 8.8% large-leaved lime tilia platyphyllos 229 4.4% goldenrain koelreuteria paniculata 224 4.3% hore-chestnut aesculus hippocastanum 168 3.2 % manna or flowering ash fraxinus ornus 121 2.3% plane platanus hispanica 121 2.3% norway maple acer platanoides 117 2.3% dominant species 3086 59.38% other species 1655 31.85% 36 takács et al. (2015) it is noteworthy that empty planting spaces, tree stumps and other miscellaneous categories make up 8.6% of the whole database, which means 490 trees were waiting to be replanted. that number continued to increase in the winter of 2013, because in addition to the winter cuts a number of individuals had to be removed during the reconstruction of kossuth lajos avenue. however, some trees were also planted in the autumn of 2013 and 2014. these changes are not included in the present analysis. this also draws attention to the vital importance of an up-to-date database, which in addition to containing the existing trees, also includes the interventions, recorded in the shortest possible time. only thus can the database facilitate effective green space management. in addition to allowing the approximate estimation of tree volume value, the size parameters of the individuals serve as input to a number of other analyses. although dbh depends on a number of parameters besides age, most importantly on species, light availability and other site conditions, the current distribution of stem diameter classes may be used to refer indirectly to the age of the stands. there is little information available in the literature concerning urban trees; there are more examples of such estimations from forest stands. sophora japonica and platanus hispanica have the largest average dbh in the szeged database, for both species it’s close to 50 cm. true, these species also have the largest standard deviation, therefore their dbh range (and probably the age as well) is higher than that of the others. similarly, there is a large standard deviation in the case of celtis occidentalis, but the average dbh is lower. tilia tomentosa, koelreuteria paniculata and fraxinus ornus have the lowest average dbh. in case of the latter two species standard deviation is also the lowest therefore they show the most homogeneous age distribution of all the species in the database (fig. 3) and are probably the youngest stands as well. looking at the age distribution of the total recorded tree population, the average estimated age is 36 years, while the software estimates the age of the oldest specimens as 103 years. the age group 15-45 makes up 66% of the total population (fig. 4). the age distribution suggests that the last great tree planting campaign in this area was at the end of the 1980’s and the early 1990’s, but significant planting actions took place between the two world wars and in the 1970’s as well. (it should be noted that these results still only refer to areas of the city within nagykörút. since these events are intimately linked with the city's structural development, the extension of the database to the outer areas might significantly modify this picture). the number of the old trees (older than 90 years) is only 22. in the case of urban trees with regard to the unfavourable ecological conditions and a fear of collapse damage – such high ages are very rare, especially in the light of szeged having been destroyed by the great flood of 1879. as a result of the destruction, even the oldest trees can only be dated back to that time. among the oldest trees are some of the planes in széchenyi square, and a few old oak trees in korányi alley. fig. 4 age distribution of the whole recorded tree population examining in detail the age distribution of the 10 most common species, the planting practices of the last hundred years are neatly outlined. it can be seen that tilia plathyphyllos, sophora japonica and platanus hispanica have the most diverse age structure, which suggests that these species enjoyed an almost unbroken popularity over the last hundred years; they were favoured throughout the last century in plantations (fig. 5). fig. 3 the average dbh of the 10 most common tree species along with the standard deviation 0 10 20 30 40 50 60 70 80 tr u n k d ia m e te r ( c m ) investigation of tree stands of public spaces in szeged 37 aesculus hippocastanum was clearly a favourite of the 1970’s, the vast majority of today's white-flowered population belongs to the age group 30-45. the species is in many ways an ideal park tree; it has a very significant microclimate-improving effect since it allows only a small percentage of the direct radiation through the canopy, and it is also very decorative through almost the whole year. the species was very popular until the late 1980’s (until the massive invasion of horse chestnut leaf miner cameraria ohridella) but by now the population is in a critical condition. the proportion of older individuals is the highest in the case of sophora japonica and platanus hispanica. however, it seems that these species have lost some of their popularity over the last 20 years, since there are very few young individuals in the database. celtis occidentalis (with an average age of 42) shows the most uniform age distribution in the observed population. this is due to the fact it is one of most urban-tolerant species; much more tolerant to the unfavourable urban conditions (air and soil pollution, drought) than other species, so it was commonly used in the past as well as in today’s urban tree planting. in the last 20-30 years, however, the focus has clearly shifted towards tilia cordata and tomentosa, fraxinus ornus and koelreuteria paniculata. the age distribution of lindens shows that from 1965 to the present day they are the fashion trees of the city of szeged fig. 5 age distribution of the 10 most common species fig. 6 health status of the 10 most common species (1: optimal 2: well-cared for, 3: deficiencies, 4: serious deficiencies 5: neglected) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% over 90 75-90 60-75 45-60 30-45 15-30 0-15 tilia tomentosa tilia cordata tilia platyphyllos sophora japonica celtis occidentalis koelreuteria paniculata aesculus hippocastan um fraxinus ornus platanus hispanica acer platanoides 1 163 39 19 27 40 10 5 35 5 4 2 122 199 60 78 142 49 48 13 30 21 3 142 372 146 414 285 165 108 32 85 79 4 4 13 0 20 4 0 7 1 0 3 5 2 10 2 2 1 0 0 0 0 1 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 38 takács et al. (2015) (gaskó 2008), and in recent decades a rejuvenation process can be observed. however, tilia tomentosa plays a more important role among younger individuals (about 50%). this is due to the fact that in recent years many perished tilia platyphyllos trees were replaced with tilia tomentosa individuals, more tolerant of the harsh urban environment. in the inner, more built-up areas of the city, it is no wonder that in the last 20 years species with relatively smaller proportions have been favoured, which would not outgrow the confined space very fast – such as fraxinus ornus. the assessment of the health status of the population was carried out according to the standards presented in the methods section. in terms of the whole observed population it is pleasing that 40% of the trees are in a relatively good state, so only minor changes of the trunk and canopy are observed. the other end of the spectrum represents individuals with severe deficiencies, i.e. where serious trunk and/or foliage damage was observed, such as deep-penetrating trunk decay, rot of the root collar or the crown which represents an imminent risk of an accident or withering of the treetop, which warns of major root damage. these symptoms require immediate and significant intervention, and in some cases make it impossible to save the tree. the database contains 60 such individuals, which makes up only 3% of the total observed population, but since the most densely populated inner city areas are affected, they require increased attention. the health status data of the 10 most common species draw attention to a number of interesting fa cts. the highest proportion of significant deficiencies (i.e. more than slight deterioration of health status), can be observed in the case of sophora japonica (77%), platanus hispanica (71%), koelreuteria paniculata (74%) and acer platanoides (73 %) (fig. 6). the first two species can be characterized with higher average ages, including a relatively high proportion of older trees. of course, this may explain the health status being worse than average. the second place of koelreuteria paniculata in these rankings is an interesting phenomenon since the age distribution suggests these trees to be relatively young, so poor health is not expected. it may be a reminder of the fact that the environmental circumstances in szeged are probably not well tolerated by this species. the same applies to the case of acer platanoides. the "serious deficiencies" or "neglected" category contain individuals with severe crown -base or root collar rot, or a strong deep -reaching parent branch decay. these two categories appear in major proportions in the case of four species, tilia cordata, sophora japonica, celtis occidentalis and aesculus hippocastanum, which seem to be the most threatened of the observed tree population of szeged. in hungary the horse chestnut leaf miner (cameraria ohridella ) spread at a very fast rate in the early 1990’s and that infection did not spare the trees in szeged either. even today, there are serious problems with the chestnut trees. in many cases, the individuals lose most of their foliage by t he end of july, or the beginning of august and start flowering again in september – which in turn greatly weakens the tree's immune system. tilia tomentosa and fraxinus ornus are in the best state of health among the recorded species. the proportion of individuals in the optimal and well-cared-for categories is way above 50%. a likely reason is that these species have the youngest stands, many of them having been planted relatively freshly. discussion and conclusion urban woody vegetation plays an important ecological role in settlements, however they are not yet always appreciated accordingly in hungary. there are very few municipalities who have an up-to-date usable tree register. in the current budget cycle (2014-2020) of the european union there is particular emphasis on the development of green infrastructure. it is no coincidence, since the optimally chosen vegetation can locally mitigate the extremes of global change to a large extent and it can significantly improve the unfavourable living conditions in urban areas. however that requires an up-to-date green space database, which shows health status, location of the individual trees, and is also informative of the performed and to do tasks. progress in hungary in this respect has first appeared in some of the bigger cities. szeged is at the forefront in this, since the city’s tree register is constantly extended and updated. such data are essential to the effective management of green areas, but keeping the data upto-date is also the most labour-intensive part. during the everyday work trees are continuously replaced, there are rejuvenation actions, cuttings, so changes often occur, which need to be continuously monitored. most of the trees are not older than 45 years; and only 10 individuals in the current database belong to the age group of more than 100 years. this can be explained by the fact that tree planting affecting today’s szeged effectively began after the catastrophe of 1879, since trees planted before that time were destroyed by the flood. wartime cuttings should also be taken into account, when the citizens of szeged needed to acquire fuel for heating. the oaks of korányi alley are among the oldest individuals that were demonstrably planted first, right following the flood. therefore when the reconstruction of the river protection wall was carried out this was precisely the reason for the need to exercise caution during the construction works, as these old, healthy individuals represent a huge unique value. the age distribution of the tree population raises interesting questions. the question of how long it is "worth it" to keep an old tree is important for decision-makers and managers; i.e. what is the age when maintenance would become significantly more expensive (due to an increasing need for maintenance works, risk of accident, curled concrete, etc.) than the positive effects of the individual. such aging populations usually have higher care needs, however due to their large canopy and consequently larger leaf surface can have a very significant air quality improving role; investigation of tree stands of public spaces in szeged 39 furthermore such important aesthetic, historical, cultural values are connected to them, which are difficult to express in monetary terms. the periods of increased tree planting are clearly visible in the age distribution data for each species, as is the fact that the constantly rejuvenated or freshly introduced species are in the best health. in some cases, however, contradictions arise, since koelreuteria paniculata individuals despite the young population are in a poor state so their "profitable" maintenance is more difficult. concerning the health status of the szeged tree population, in the case of certain species the proportion of the “deficiencies” category is relatively high. white-flowered aesculus hippocastanum trees are especially in poor health. when the funding becomes available most probably the red-flowered variant of chestnut (aesculus × carnea) will be used to replace these, which seems to be resistant to the pest destroying the other type. a noteworthy initiative to improve the health of the remaining population was the opening of the formerly asphalt-surrounded planting spaces in a substantial part of szentháromság street. the open soil surface was covered with mulch and shrubs, which is supposed to greatly improve the state of the stand through allowing a better infiltration of rainwater. the poor health of the trees is probably related to the sometimes extremely parched urban soils. unfortunately it is possible that the stand is already so heavily degraded that even this measure will not help. the health status of species represented by older stands (tilia platyphyllos, platanus hispanica and sophora japonica) is also worse than the average, the category of major deficiencies appears in their case. at present, tilia tomentosa has the best health status, which may be the result of partly the young age of the stands, and partly of the fact that this sub-mediterranean species tolerates urban conditions better than others. therefore, it is an alternative to be considered when replacing other linden species. although the data presented in this study involve only a part of the total of szeged’s street tree population, even the current database allows a highly complex analysis, of which here only species composition, age-, size and health status distribution were examined. the establishment of the appropriate species composition is very difficult. a lot of aspects should be taken into account by the maintainer; different public places have different needs and constraints thus different species can mean the ideal choice. in recent years fraxinus ornus became fashionable; it is a popular species in fresh plantations. however planting a species with a relatively small leaf surface and high transmissivity in certain places (e.g. heavily used public squares) could contradict modern climate-conscious urban planning principles. the answers to these questions may become easier to find through indepth data analysis and further research, which is the aim of our research group and also meets the needs of the municipality. references andrade, h., vieira, r. 2007. a climatic study of an urban green space: the gulbenkian park in lisbon (portugal). finisterra 17, 27–46. balázs, b., unger, j., gál, t., sümeghy, z., geiger, j., szegedi, s. 2009. simulation of the mean urban heat island using 2d surface parameters: empirical modeling, verification and extension. meteorological applications 16, 275–287. doi: 10.1002/met.116 bowler, d.e., buyung-ali, l., knight, t.m., pullin, a.s. 2010. urban greening to cool towns and cities: a systematic review of the empirical evidence. 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park. hortscience 45, 83–86. loehrlein, m. 2014. sustanable landscaping. principles and practicles. taylor & francis group, 978-1-4665-9321-3 (e-book). mcpherson, e.g. 2003. a benefit-cost analysis of ten street tree species in modesto, california, u.s. journal of arboriculture 29, 1–8. doi: 10.1093/treephys/18.8-9.537 nowak, d.j., crane, d.e., stevens, j.c. 2006. air pollution removal by urban trees and shrubs in the united states. urban forestry & urban greening 4, 115–123. doi: 10.1016/j.ufug.2006.01.007 péczely, gy. 1979. éghajlattan. tankönyvkiadó budapest. shashua-bar, l., pearlmutter, d., erell, e. 2011. the influence of trees and grass on outdoor thermal comfort in a hot-arid environment. international journal of climatology 31, 1498–1506. doi: 10.1002/joc.2177 takács, á., kiss, m., gulyás, á. 2014. some aspects of indicator development for mapping microclimate regulation ecosystem service of urban tree stands. acta climatologica et chorologica (47–48), 99–108. unger, j. 1997. városklimatológia – szeged városklímája. acta climatologica et chorologica univ. szegediensis 31/b (urban climate special issue), 69. zhang, z., lv, y., pan, h. 2013. cooling and humidifying effect of plant communities in subtropical urban parks. urban forestry & urban greening, 12, 323–329. doi: 10.1016/j.ufug.2013.03.010 http://dx.doi.org/10.1016/j.landurbplan.2010.05.006 http://dx.doi.org/10.1093/treephys/18.8-9.537 introduction study area methods results discussion and conclusion references tree-ring width and its interrelation with environmental parameters journal of environmental geography journal of environmental geography 8 (3–4), 53–59. doi: 10.1515/jengeo-2015-0012 issn: 2060-467x tree-ring width and its interrelation with environmental parameters: case study in central hungary zsuzsanna ladányi*, viktória blanka department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: ladanyi@geo.u-szeged.hu research article, received 1 september 2015, accepted 20 november 2015 abstract tree ring width is influenced by several internal and external factors, among which climate became one of the most dominant due to the altering conditions and patterns of precipitation and temperature. the study aims to analyse the interrelationship between tree ring-width and the dominant environmental parameters in a landscape exposed to water scarcity in the past decades due to climate change and human interventions. scots pine (pinus sylvestris), black locust (robinia pseudoacacia) and white poplar (populus alba) plantations were sampled to reveal their exposure to climatic forcing and water scarcity (different water availability). correlation and similarity analysis were carried out to compare the calculated ring-width indices to climatic parameters and aridity indices. tree ring sensitivity was assessed to reveal the impact of water scarcity on yearly ring-growth. spatial overlapping of significance levels and mean sensitivity with the hydrological changes of the past decades were evaluated to reveal presumable spatial differences of the investigated samples. in the study area (south danube-tisza interfluve) droughts and the deep groundwater table had both impacts on tree growth. the spectacular decrease of ringwidth corresponds to the drought years determined by the investigated aridity indices. the relationship between the climate parameters and the ring-widths varies spatially with the changing site conditions. the highest level of correlation coefficients was experienced in areas with the lowest level of water availability. ring-width sensitivity assessments showed an increasing tendency of sensitivity when comparing the consecutive decades, except for samples with favorable water availability. keywords: tree ring, sensitivity, climate change, water scarcity introduction recent climate change influences the species distribution and tree growth in many regions of europe (lenoir et al., 2008; way and oren, 2010) and due to the projected changes in climate extremities further impacts are expected (mátyás, 2010; lindner et al., 2014). tree responses depend on both internal (species characteristics) and external (local site conditions) factors (fritts, 1976). climate change results in both positive and negative responses on forests, e.g. drought-induced increase of mortality and species range retraction (allen et al., 2010; hlásny et al., 2011), increased risk of forest fires (venäläinen et al., 2014), and increased productivity at higher elevations and latitudes (jolly et al., 2005). due to the experienced impacts of the past decades, there is an increased need for the exact knowledge on how and to which extent the factors influence the functioning of the environmental systems. consistent with global and continental trends an increasing trend of the regional temperature was experienced in the carpathian basin. there is also a rise in the regional intensity and frequency of extreme precipitation, while the total precipitation has decreased (bartholy and pongrácz, 2007). as a result, the area has been increasingly exposed to hydro-climatic extremes e.g. drought, inland excess water, high magnitude flood (pálfai and herczeg, 2011; mezősi et al., 2014). according to regional climate model predictions, more areas will face increasing temperature and changing precipitation conditions (bartholy, 2011; blanka et al., 2013), and the further increase of the hydroclimatic extremes is also projected (mezősi et al., 2014). the relation between tree ring growth and climatic parameters was investigated for several species in hungary. the impact of precipitation on turkey oak (quercus cerris) was investigated by szabados (2008), where tree rings were sensitive to the annual changes of precipitation, furthermore precipitation from april to june proved to be the most important period of tree growth. kern et al. (2013) carried out separate investigation on early and latewood width of pedunculate oak (quercus robur), where the correlation analysis revealed relatively strong response to growing season precipitation for both, and the strongest correlation was found with the precipitation total from november of the year preceding the tree ring growth to august of the growth year. the impact of climate change on beech (fagus sylvatica) was assessed by garamszegi and kern (2014), who identified late springearly summer precipitation as the primary climatic factor governing the beech growth. the authors indicated no evidence of a distinct decline in radial increment, but a significant increase in climatic impact on growth including probable changes and shifts in the vegetation period. szabados et al. (2012) analysed black locust (robinia pseudoacacia l.) samples from nyírség region, and found the 54 ladányi and blanka (2015) precipitation of may-july period, especially the precipitation in may as the most determinant for tree increment. the increasing temperature of the vegetation period has negative impact on tree growth. the consequences of climate change and the anthropogenic activities (e.g. water drainage, water exploitation) contributed to groundwater table decrease in significant part of the great hungarian plain (pálfai, 1994; kuti et al., 2002). the highest lowering is experienced in the danube-tisza interfluve, where the missing groundwater resource is approximately 6-9 km3 in dry years that almost equals to the annual water consumption of hungary (rakonczai, 2011, 2014). several studies investigated the causes and the consequences of this phenomenon in the past 3 decades and estimated the role of the natural and anthropogenic factors. nowadays, the natural factors (decreasing precipitation, increasing temperature and evapotranspiration) are assigned as the most dominant contributing parameters to the phenomena, especially on the higher-elevated part of the interfluve (völgyesi, 2006; szanyi and kovács, 2009; rakonczai, 2014). the water scarcity became the most dominant limiting factor for vegetation in this region and results in changes of wetland habitats (biro et al., 2007; deák, 2010; ladányi et al., 2010; rakonczai, 2011) and decreased forest productivity determined by remote sensing (kovács, 2007). the knowledge of forest responses to different hydro-climatic changes in this region is scarce. this study aims at the investigation of the interrelationship between tree ring-width and t dominant environmental parameters by correlation analysis of time series and by the assessment of their spatial distribution. the study area is highly exposed to water scarcity, thus the main question is how tree-ring sensitivity is influenced by the different availability of water. study area the study area is located between the hungarian sections of the danube and tisza rivers in the carpathian basin (fig. 1). the area developed of fluvial sediments, the ancient alluvial fan of the danube river (borsy 1989). the surface is covered by blown sand on most of the area, but silty and clay sediments are also appear close to the rivers. the area is influenced by continuous groundwater table decrease compared to the 1970s due to climate change and anthropogenic activities (rakonczai, 2011). the present groundwater level has high spatial variability: in the highly elevated areas it varies between 5-20 m (e.g. illancs microregion in bácska plain mesoregion), and towards the rivers it decreases. close to the rivers the depth of groundwater table is around 1 m or less. thus vegetation growth is highly dependent on precipitation, especially on elevated areas. these areas are the most exposed to water shortage in drought years, thus vegetation development is strongly influenced by the changes of the climate parameters. the annual mean temperature is around 11 °c and the annual amount of precipitation is between 500 600 mm. in july the mean temperature is around 21 and 23 °c, the precipitation in the summer half-year is at about 300 mm (omsz, 2014). the temperature shows fig. 1 location of the study area in the carpathian basin and the sampling sites tree-ring width and its interrelation with environmental parameters… 55 significant yearly variability, however, an increasing tendency of the temperature can be clearly d etected. since the 1990s, warm years occurred more frequently. in terms of the precipitation conditions of the area, decreasing tendency can observed, years drier than the average occur more frequently and the temporal distribution of precipitation is less favorable. therefore, drought years occurring increasingly frequently. the dominant land use type in the area is arable land based on corine land cover 2006. the proportion of forests is low and large part of them are planted with introduced species (e.g. robinia pseudoacacia, pinus sylvestris and pinus nigra). methods scots pine (pinus sylvestris) (abbr. pine), black locust (robinia pseudoacacia) and white poplar (populus alba) (abbr. poplar) planted forests were investigated to analyse the sensitivity and the exposure of forests to climate parameters. altogether 10 pine and 10 poplar trees from two forests were sampled in the highest-elevated, blown sand covered areas in the bácska plain mesoregion (illancs microregion), further 5 pine and 9 black locust plantations were also investigated at lower elevation of the sand ridge (danube-tisza plain mesoregion) on soils characterised by sand, silty sand and silt textures. during sampling tree height, tree health, foliage and trunk were considered. the age of trees varies between 23-47 years (table 1). table 1 age of the investigated samples age of trees (illancs, bácska plain mesoregion) nr of trees (pcs) age of trees (danube-tisza plain mesoregion) nr. of trees (pcs) pine 31-45 yrs 10 24-37 yrs 5 black locust 23-47 yrs 9 poplar 27-43 yrs 10 samples were mostly collected by increment borers, though trunk slices were also studied, where investigations were carried out for 4 main directions. after sample preparation ring widths were measured using lintab 5 tree-ring measuring station and tsap-win software. ring widths vary not only with the fluctuations of environmental conditions, but also with systematic changes in tree age. the standardization of ring-width measurements are necessary to remove the decrease in size associated with increasing age of a tree (alestalo, 1971). thus, ring-width indices were calculated by fitting a curve to each measured series and dividing each ring width by the corresponding value of the curve (fritts, 1976) (fig. 2 ). detailed assessment was carried out at the highest elevated illancs microregion. here, ring-width indices were compared to climate parameters (annual precipitation (pa), precipitation of the vegetation period (pv) and mean temperature in the vegetation period (tv)) based on the neighboring meteorological stations (szeged, kiskunhalas), furthermore to drought indices that combine basic meteorological parameters to describe the yearly exposure to water scarcity or surplus. in the assessment pálfai drought index (pai, pálfai, 1990) and forest aridity index (fai, führer et al., 2011) were calculated (eq.1-2). for the comparison of climatic indices and ring-width indices correlation coefficients were calculated. the similarity of ring-width and drought index pattern was also evaluated, based on the gleichläufigkeit test method (schweingruber, 1989), which analyse the agreement between the interval trends of two curves. the similarity was expressed in percentage. fig. 2 method of ring width index calculation forest aridity index (führer et al., 2011): fai = tvii−viii pv−vii+pvii−viii ∗ 100 (eq.1) where, t: monthly mean temperature, p: monthly precipitation sum pálfai drought index (pálfai, 1990): 321 ***100* )( )( kkk mmp ct pai viiix viiiiv     (eq.2) where, t: monthly mean temperature, p: monthly precipitation sum, k1: correction factor estimating heat waves, k2: correction factor estimating duration of dry spells, k3: correction factor estimating groundwater depth. based on the calculated ring-with indices, ringwidth sensitivity was also assessed (eq. 3-4) which showed the variability of ring-widths in the consecutive years reflecting changing environmental conditions. ring width sensitivity was calculated following fritts (1976): 𝑆𝑖+1 = (𝑥𝑖+1 − 𝑥𝑖 ) ∗ 2 (𝑥𝑖+1 + 𝑥𝑖 ) (eq. 3) where si+1 is the sensitivity of the tree rings in i+1 year, xi is ring width mean tree-ring sensitivity was defined as: 𝑆 = ∑ 𝑆𝑖 𝑛 − 1 𝑖=𝑛−1 𝑖=1 (eq. 4) where n is the total number of tree-rings 56 ladányi and blanka (2015) according to horváth et al. (2003), mean tree ring sensitivity classes are the followings: s<0.2 low sensitivity 0.2<s<0.3 medium sensitivity s>0.3high sensitivity at the study sites of danube-tisza plain mesoregion tree-ring sensitivity was calculated, furthermore correlation coefficients of ring-width and pai and fai were calculated for spatial assessment. based on the results, spatial assessment was carried out, where the correlation coefficients of pai and fai and the tree-ring sensitivity were analysed to reveal the effect of exposure to water scarcity (different water availability) on tree growth. results assessment of tree samples in the highest elevated illancs microregion pine samples showed increasing variability in the past two decades compared to previous periods (fig. 3a). the lowest ring-width indices were experienced in the most severe drought years (e.g. 1993, 2003) and the humid periods (e.g. the end of the 1990s) were indicated by the highest values. the period between the end of the 1970s and the early 1990s showed the lowest variability of ring-width indices. a strong similarity of the ring-width to aridity indices could be identified. the percentage of the years, where the interval trends of two curves agree, varies between 64.3–85.3% and 60.0–85.3% in case of pai and fai respectively. the percentage values were somewhat higher in case of pai compared to fai at all pine samples. poplar samples also showed increasing variability in the past two decades compared to the previous periods (fig. 3b). the lowest and highest ring-width indices were experienced in the same periods as it was observed in case of pine trees. in this case the 1980-1990 decades had the lowest variability of ring-width indices. the similarity of the ring-width and the aridity indices of poplar samples were similar to the pine, percentage values related to pai and fai were 61.0– 81.4% and 60.5–88.4%, respectively. however, in case of poplar trees the higher percentage values varied between pai and fai from sample to sample and fai showed higher similarity in case of 7 samples. as a result of the correlation analysis, pai and the fai values indicated the highest correlations with the ring-width indices in the case of all samples (fig. 4a). the correlation was significant at the 0.01 level and the 0.05 level for 50-50% of the samples, respectively. the relationship of the ring-width indices with the precipitation (pa and pv) was lower compared to the aridity indices, and in case of a few samples the correlation was not significant, however the correlation with the precipitation of the vegetation period (pv) was somewhat higher. the lowest level of correlation could be identified in case of the mean temperature of the vegetation period (tv) with the ring-width indices, and more than half of the samples showed no significant correlation with this factor. the relationship between the investigated variables was not so evident like it was in case of the pine trees, they showed a higher standard deviation. pai was the investigated factor, where the most samples showed significant relationship with the ring-width indices (fig. 4b). the relationship with the precipitation was higher compared to the temperature in this case as well. the calculated decadal mean tree-ring sensitivity of the pine samples indicated medium and high sensitivity of ring-widths for almost the whole period, except for some samples between 1970-1980 and 1980-1990 periods (fig. 5). an increasing tendency in sensitivity values was identified towards the past two decades. fig. 3 mean, minimum and maximum values of the investigated ring-width indices and the similarity between the samples and the aridity indices of pine (a) and poplar samples (b) tree-ring width and its interrelation with environmental parameters… 57 similarly to pine samples, the calculated decadal mean tree-ring sensitivity of poplar also indicated medium and high sensitivity f ring-widths for almost the whole period (fig. 5b). the increasing tendency of sensitivity values was much more intensive compared to the pine samples and for the past decade, all samples were described by high sensitivity values. assessment of samples at danube-tisza plain mesoregion on the lower lying areas ring-width indices show lower correlation with the pai and the fai values. only 21 % of the samples (1 pine and 2 black locust samples) showed significance at 0.01 level and further 57 % at the 0.05 level with the pai. the correlations with the fai were similar to the pai, except for a few samples. the correlation was significant at the 0.01 level and the 0.05 level for 64% of the samples. the similarity of the ring-width with the pai varies between 60.7%–77.1% for pine, similarly to the samples from the illancs microregion. the variability of the similarity values were higher in case of the black locust samples (48.8%–82.6%). with the fai the similarity values were slightly lower (57.1%–75.0% for pine and 51.2–71.7% for black locust). in case of only a few samples (4 of the 14) similarity was higher with the fai. a strong similarity of the ring-width with the aridity indices was identified for black locust. the percentage of the years, where the interval trends of two curves agree, varied between 64.3–85.3% and 60.0–85.3% in case of pai and fai, respectively. the percentage values were somewhat higher in case of pai compared to fai at all samples. the decadal mean tree-ring sensitivity for samples of the other part of the study area was lower compared to the samples of illancs microregion (fig. 6). in case of pine mostly low or medium sensitivity was observed, only one sample showed high sensitivity. the tree ring sensitivity of the sampled pine trees not increased in the last decades as it was observed in the illancs region. the samples also indicated low or medium tree ring sensitivity in case of black locust and few sample showed high sensitivity. the sensitivity changes of the fig. 4 correlation factor (r) between the ring-width index of the samples and the investigated variables in case of pine (a) and poplar samples (b); pai: pálfai aridity index, fai: forest aridity index, pa: annual precipitation, pv: precipitation of the vegetation period, tv: mean temperature of the vegetation period. the black lines represent the significance levels (0.01 and 0.05) fig. 5 tree ring sensitivity (illancs, bácska plain mesoregion) in case of pine (a) and poplar samples (b). the black lines represent the thresholds of low, medium and high sensitivity fig. 6 tree ring sensitivity (danube-tisza plain mesoregion) in case of pine (a) and black locust samples (b). the black lines represent the thresholds of low, medium and high sensitivity 58 ladányi and blanka (2015) black locust trees showed higher variability, and most of the samples did not show increasing values, only in case of a few samples increasing sensitivity was observed and the rate of increase was lower compared to the samples of illancs microregion. spatial assessment of ring-width and site conditions the effect of exposure to water scarcity (different water availability) on tree growth was revealed by spatial assessment. the significance level of correlation between ring-width index and aridity indices, and the mean tree ring sensitivity were overlapped by the relative groundwater depth on figure 7. in case of pine samples the strength of the correlation increased with the decreasing groundwater depth in case of both pai and fai. samples closer to the rivers, where groundwater level situated closer to the surface, no significant relationship was identified. similar spatial pattern was recognized in case of the black locust compared to pine samples. the poplar samples from the highest elevated illancs microregion also confirmed the revealed spatial relationship between the tree growth and the e xposure to water scarcity. the spatial pattern of mean tree-ring sensitivity values (calculated for the whole tree sample) indicate similar differences than the correlation pattern. high sensitivity was identified in case of the samples from the illancs microregion and from areas of low groundwater table. all the other samples belonged to the medium and low categories of sensitivity. discussion and conclusions ring width is influenced by several external factors that can be both permanent and variable in a few decades-long period. soil conditions and relief are among the factors that do not significantly change, however, meteorological and hydrological factors can vary significantly. as it is well-known, severe drought years result in narrow ring widths, while humid years cause wide increment. the changes of the groundwater availability can also be a limiting factor of tree growth. in the study area droughts and the deep groundwater table have both impact on tree growth. tree responses to these changing conditions were reported earlier from this area: the decrease of green biomass and foliage in drought years were described by kovács (2007) using remote sensing methods. the spectacular decrease of ring-width (in arid years even below 1 mm for both pine and poplar in the highest elevated illancs microregion, where the most significant high groundwater table decrease was recorded since the 1970s) corresponds to the drought years determined by the investigated aridity indices. their yearly changes compared to the changes of the ring-width indices are also relatively high and varies between 60-88% in illancs region. the other samples are characterized by the same or lower similarity when closing to the rivers or areas of more favourable water supply. the relationship between the climate parameters and the ring-widths varies spatially with the changing site conditions (e.g. elevation, groundwater depth, soil). the highest level of correlation coefficients were experienced in the highest elevated illancs microregion, while the lowest ones occurred on the relatively lower lying areas, especially near to the tisza river, where ground-water supply ensures sufficient water for tree growth. the ring-width sensitivity assessments showed an increasing tendency of sensitivity when comparing the consecutive decades. along with the increasing extremities and the lowering groundwater-table, the yearly variation of ring-with increases to the highest rate in illancs microregion, while towards the rivers, the increasing tendency becomes moderate, and in certain cases even no trend can be observed. the investigated planted forests are in a landscape that is dominantly used by agriculture and which is exposed to high water scarcity. the exposure to climatic forces will tend to continue (bartholy et al., 2011; blanka et al., 2013; mezősi et al., 2014) that is why the more ex fig. 7 spatial distribution of correlations between pine (green), black locust (red) and poplar (orange) samples and aridity indices in the case of pai (a) and fai (b), and spatial distribution of mean ring 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669–688.doi: 10.1093/treephys/tpq015 http://onlinelibrary.wiley.com/doi/10.1111/tgis.2007.11.issue-6/issuetoc http://landscape.geo.klte.hu/pdf/agd/2010/2010v4is1_2.pdf http://landscape.geo.klte.hu/pdf/agd/2010/2010v4is1_2.pdf http://landscape.geo.klte.hu/pdf/agd/2010/2010v4is1_2.pdf http://www.intechopen.com/articles/show/title/effects-and-consequences-of-global-climate-change-in-the-carpathian-basin http://www.intechopen.com/articles/show/title/effects-and-consequences-of-global-climate-change-in-the-carpathian-basin http://volgyesi.uw.hu/dokuk/homokhatsag.pdf http://volgyesi.uw.hu/dokuk/homokhatsag.pdf introduction study area methods results assessment of tree samples in the highest elevated illancs microregion assessment of samples at danube-tisza plain mesoregion spatial assessment of ring-width and site conditions acknowledgements references physical, chemical and biological aspects of human impacts on urban soils of szeged (se hungary) journal of env. geogr. vol. i. no. 3-4. pp. 7-14 evaluation of changes and instabilty of water content using remote sensing methods in a nature conservation area kovács, f. 1 1 department of physical geography and geoinformatics, university of szeged, hungary abstract the most significant landscape forming factors in the great hungarian plain are humans and water. before the regulation of the waterways one quarter of the present-day territory of hungary belonged to the complex network of periodically or permanently inundated flood plains, marshes and swamps. owing to human activities and the climatic changes observed in the last decades, processes that indicate landscape change have occurred in the great hungarian plain (rakonczai j. 2007). loss of wetlands is a major process of landscape change. evaluation of geographical changes caused primarily by water shortage is a difficult task as on the one hand only a limited data set is available and, on the other hand all the processes taking place in the area have to be known and understood in order to recognize the exact change. habitats are extremely changeable and after the early summer floods, sometimes they entirely dry up to the end of the season. for detection and accurate evaluation of the long term changes lasting from the 19 th century to present days the spatial and temporal development of instability has to be revealed. this has been determined on the basis of a series of high time resolution satellite images by digital image processing methods for the geographically very interesting period 19992003. keywords: wetlands, excess water, change, instability, landscape dynamics, landsat, spectral index rationale a new phase of landscape evaluation is indicated by the assumption that in a rather short period of time change is expected in the climatic conditions. as a result of the likely climate change and the human activities increasing aridification can be observed in the great hungarian plain. all the natural processes included in aridification are long-period ones and affect every other factor and process. water shortage induces changes in the landscape (barna gy. 2008, rakonczai j. – kovács f. 2008), which are aggravated by the forecast that the acceleration of degradation can be expected in the near future. the water shortage has an adverse effect in the summer period, and in the wetland ecosystems the persistently low water level may lead to landscape transformation. examination of the dynamics of those landscape factors that are dominant due to the local characteristics (e.g. water coverage, vegetation) is of key importance in the accelerating degradation processes (kovács f. 2007, ladányi zs. et al. 2009). the amplitude of multi-years period of fluctuations of a phenomenon can be naturally higher than the shortterm effects of climate change, which makes the geographic evaluation of the effects observable on the surface more difficult. the rate and speed of change settles whether it is change or fluctuation, this is why the longterm studies are of considerable importance. the main point in the study of change is not the values the studied variable took on in a time series, but rather the values it could have taken on at a given time, and whether there is a change in these values or not. consequently the change of process is interpreted as the change of the probability distribution of the possible values (nováky b. 2003). the analysis of extreme situations could present a basis for the determination of the possible range of values characteristic of a geographic phenomenon. the necessity of such studies is proven by the prognosis for the near future, in which extreme weather events are given high priority. the increase in excessive rainfall events (i.e. short but intense precipitation) and in drought frequency also affects the appearance of surface water. analyses at high spatial and temporal resolution make the evaluation of instability possible, which is essential for a detailed evaluation of change. the study area saline areas located in the danube valley, having one of the most extreme characteristics in hungary, have been put under protection. “… and in the absence of levees the river flooded the low-lying areas of the upperkiskunság… the former traveler found himself in the world of thousand island…” (illyés b. 1992). the nearby early holocene main river bed and the kígyós brook were navigable (erdélyi m. 1960). approximately 75% of the danube plain was in near-natural state in the second half of the 18th century, however, at the end of the 1960s the proportion of standing water was only 0.3% (pécsi m. 1967, bíró m. – molnár zs. 1998). the remaining wetlands are highly important from the point of view of nature conservation and tourism, but it is more and more difficult to maintain their present condition as they are very sensitive to environmental changes. the strictly protected upper kiskunság lakes, classified as natural habitat complex in the national ecological network, belong to the category of shallow water (fig. 1). half of the 13,000 ha study area is national park, and 85% of the area is part of the ecological network. 44% of the study area is covered by alkaline lakes, swamps and grasslands. one third of the 50 m area 8 kovács f. joeg i/3-4 8 surrounding the wet patches is not near-natural in character. comparing the maps of the third military survey in 1882 with the present landscape it can be concluded that in most cases lakes and swamps can be found in the same place where there were wetlands earlier, only 14% of these areas have become arable or pasture. in case of the groundwater under pressure, a 2.5-3.5 m difference in water level can be observed within a distance of 1.5 km (molnár b. – kuti l. 1978). the salt content of the lake water is 700-1200 mg/l (3000 mg/l in kelemenszék) (schmidt a. 2003). fig. 1 land cover of the upper kiskunság lakes recent geographical processes endangering wetlands in the course of flood regulation and inland drainage one million ha wetland habitats were destroyed (istánovics v. – somlyódi l. 2002). in the danube-tisza interfluve 16,000 ha swampy, marshy areas and 38,000 ha saline grasslands were damaged (láng i. et al. 2007). it is only the precipitation and the groundwater that can recharge water. based on the data set of 135 years it can be stated that there is a decrease in precipitation concerning the yearly, seasonal and monthly means (láng i. et al. 2007). the decrease in the period of 1956-2005 was more than 6%; there is a decrease in precipitation in spring, summer and winter as well (bihari z. et al. 2006), consequently the time periods important in the recharge of lakes are also affected. despite there are favorable periods in aridification, a significantly decreasing trend in precipitation can be observed (konecsny k. 2006, pálfai i. 2007). in the danube-tisza interfluve there was a more than 4.8 km 3 deficit in groundwater in 2003 compared to the 1970s (rakonczai j. 2007), therefore less and less groundwater flows from the higher grounds to the lakes. the winter water recharge, necessary for the lifecycle of alkaline lakes, does not take place for some time. in the danube-tisza interfluve all lakes have been in extreme danger since 1980, as they are dry even in spring (iványosi sz. a. 1994). spatial and temporal analyses could reinforce the main objective of conservation planning i.e. the rehabilitation of degraded habitats. principles of the analysis and the applied remote sensing methods the extreme seasonal instability of lakes and swamps is an important aspect in the accurate evaluation of wetlands sensitive to external factors, and thus it is suitable for the spatial and temporal evaluation of the process of change. two types of evaluation could be applied to assess the degree of changes: one covering a long time period, based on maps, photos and images; and another one covering a shorter time period, based on photos and images, but having high time resolution. making use of the accurate maps made since the 19th century, the aerial photographs taken since the 1950s, and the satellite images created since the 1980s, the last 130 years can be analysed. for a dynamic landscape evaluation based on remote sensing methods the time resolution should be increased in case of extremely sensitive areas (e.g. saline areas) as the dynamics of moisture conditions can be given only in this way. for the analysis of fluctuation a short period would be ideal when many different states of the wetlands are observable. the evaluation of a very dry and a very wet period is needed for the determination of the possible range of values, therefore the years 1999 and 2000, when there were extreme moisture conditions in the study area, could be appropriate reference periods (fig. 2). the increase in the frequency of short but intense precipitation events and droughts is one of the local effects of climate change. there is a possibility that the lake beds recharge quickly but it is also possible that they dry up quickly and permanently. the processes taking place in the extreme year of 2000 could be characteristic of the near future. the spatial-statistical analysis of extreme weather events can contribute to the examination of the hydrological budget of wetland habitats as the objective spatial delimitation based on time series cannot be accomplished by the classical mapping methods. joeg i/3-4 evaluation of changes and instability of water content using remote sensing methods… 9 although drought and aridity are characteristic of the climate of the study area, the problem of aridification is the most serious if there is no water in the area even in the early summer period. taking advantage of the remote sensing data acquisition the differences between the years have been analysed according to the most favorable i.e. the wettest conditions, therefore the images for june have been added to the data set for each year under scrutiny. if even this optimal state is unfavourable, wetlands are in a critical condition. thanks to the database of the us geological survey and the department of physical geography and geoinformatics at the university of szeged, 22 landsat tm and etm+ multispectral images are available for the short time period between july 1999 and october 2003 (table 1). the study makes it possible to analyse the effects of a short and wet period within a period becoming more and more arid in the long run. aerial photographs taken in 2000 were used for reference analysis. making use of the data content of multispectral images three different spectral indices were applied (erdas support, mucsi l. 2004, szatmári j. 2005). moisture conditions were determined by the wetness index of the tasseled cap, which has two versions because of the fig. 2 precipitation in izsák in the period 1998-2003 (source: hydrological almanach) table 1. remote sensing and cartographic database year of mapping (scale) change analysis satellite images (name of sensor) change analysis satellite images (name of sensor) instability analysis 1783 (1:28.800) 1859 (1:28.800) 1882 (1:25.000) 1960 (1:10.000) 1982 (1:10.000) june 1986 (landsat tm) june 1994 (landsat tm) june 2000 (landsat tm) june 2002 (landsat etm) june 2006 (landsat tm) june 2007 (landsat tm) 17. july 1999. (landsat etm) 09. aug. 1999. (landsat etm) 28. oct. 1999. (landsat etm) 14. apr. 2000. (landsat tm) 08. june 2000. (landsat etm) 10. july 2000. (landsat etm) 11. aug. 2000. (landsat etm) 20. aug. 2000. (landsat etm) 14. oct. 2000. (landsat etm) 07. mar. 2001. (landsat etm) 03. may 2001. (landsat etm) 27. june 2001. (landsat etm) 30. aug. 2001. (landsat etm) 22. feb. 2002. (landsat etm) 23. june 2002. (landsat etm) 26. aug. 2002. (landsat etm) 22. mar. 2003. (landsat etm) 14. apr. 2003. (landsat etm) 16. may 2003. (landsat etm) 20. july 2003. (landsat tm) 06. sept. 2003. (landsat tm) 15. oct. 2003. (landsat tm) 10 kovács f. joeg i/3-4 10 different sensors: witm = 0.1446tm1 + 0.1761tm2 + 0.3322tm3 + 0.3396tm4 – 0.6210tm5 – 0.4186tm7 wietm+= 0.262etm1 + 0.214etm2 + 0.092 etm3 + 0.065etm4 – 0.762 etm5 – 0.538 etm7 where: tm1, tm2. …, tm7, and etm1, etm2, …, etm7 are different wavelength ranges. water mask index shows the amount of water in wetlands: wm=tm5/tm2. the vegetation cover on areas with different moisture content was determined by the normalized difference vegetation index: ndvi=(tm4–tm3)/ (tm4+tm3). the result maps including the categories of “open water surface and area of high water content,” “waterlogged area,” “dry surface” were created by complex queries, in which the data of index images (wi, wm, ndvi) were taken into account. if one of the indices indicates water in an area, which is neither dry nor covered by water according to all indices, it is categorized as „area of high water content”. from near-natural to present-day conditions – long-term changes of wetlands on the basis of the entire data set the changes of the last 130 years can be analysed, but a more detailed analysis of the last 50 years – which are important in terms of aridification – is also possible (fig. 3). the data of the third military survey in 1882 are interpreted as reference values; the river regulation had an effect on the extent of inundation, however, climate change did not. the effect of flood regulation and inland drainage is well demonstrated by the rapid drying up in the period of 1882-1960, when two thirds of the water disappeared. beside the water management in which water considered to be harmful was drained quickly, in case of lakes and marshes recharging only from precipitation aridification also appeared in the second half of the 1970s. as a consequence, another two thirds of the remaining wetlands became characteristically dry surfaces until 1986. in 100 years the area of wetlands decreased by more than 88%. the extension of areas of high water content in 2002 and 2007 was similar to the unfavourable year of 1986; however, in the years of 2000 and 2006 there were high water content values (fig. 4). the proportion of wetlands was 32% in the study area at the time of the third military survey, but in 1986 and 2007 it was only 4-5%. until the end of the 1980s serious spatial and qualitative degradation could be observed in wetlands. the positive effects of the increasing precipitation levels observable from the end of the 1990s are not general, only the temporary marshes are able to regenerate, which hardly store water and their territorial fig. 3 decrease in wetlands and transformation of the ecological network joeg i/3-4 evaluation of changes and instability of water content using remote sensing methods… 11 values are variable. the landscape cannot regain its original state. one hundred and twenty years ago the waterlogged, marshy areas were much more characteristic and permanent, and they had a buffer zone and ecological corridor function. the decrease in the spatial extension of water patches, and the increase in their number indicate their isolation from each other and an increase in their vulnerability. in 1950 only 75% of the open channels were occupied by four lakes, but in 2002 it was actually 100%. the analyses indicate that all the water surfaces are changing, therefore it is probable that not only the lakes, but also all the wetlands disappear. an area can be prognosticated at the upper kiskunság lakes, which is drying up, but in the rainy periods gets active in a human lifetime. the evaluation of instability besides the spatial and statistical analysis of the extremities and the instability, it is important to specify the changes found in the long-term research during the detailed evaluation of the five-year period between 1999 and 2003 (fig. 5). the ratio of precipitation amount for three months is the ratio of the precipitation sum for the month of recording and the previous two months to the sum of the average precipitation measured in the same months between 1873 and 2001 at the nearby station of kecskemét. the retrospective index clearly shows that in recent times precipitation is the main source of water recharge. it explains the difference between the values measured in august and it is visible why the relative increase in precipitation in july and september 2000 did not have any effect on water level. at the beginning of 2000 the extension of wetlands was conspicuous according to the ratio of precipitation amount as well. at maximum water content one-third of the study area is inundated. due to the meteorological factors the values measured in april decreased within a short time (in 2000 three-fourths of the monthly mean temperatures were above the average). the extension of wetlands in june is half of that in april and by july this value is also halved. the extension of wetlands in october is only 10% of the maximum extension observed a few months earlier. approximately 4000 ha of wetlands disappeared between april and october, which means an average decrease of more than 22 ha/day. in case of a shallow fig. 4 change in the extension of wetlands fig. 5 connection between the extension of water surfaces and the amount of precipitation 12 kovács f. joeg i/3-4 12 average depth of 30cm, it means the evaporation and percolation of 0.12 km 3 of water. this is much greater than the ever known yearly water shortage or excess water in the area. out of the two largest lakes, the kelemen-szék and the zab-szék, the latter one has the most stable boundaries. the rate of decrease is 1.1 ha/day on average, but maximum 2.6 ha/day. in case of deviation from the average, the extension of wetlands halved from 2000 (1000ha) to 2001. in case of certain standing water this value modified from 30-100 ha to 8-35 ha by the next year. the year 2000 can be used for the modeling of a possible maximum inundation. the precipitation values were under the average in the second half of the year 2000, in the second quarter of 2001, and in the first halves of 2002 and 2003. despite the total amount of precipitation was above the average in 2001, low inundation values were registered both in this year and in 2002. therefore it can be concluded that the effect of a favourable year is not enough for stopping the unfavourable processes. this was also experienced at szappan-szék by hoyk e. (2006). the mosaic of landscape features raises the hope that aridification is not irreversible. surface water connection was observable between kelemen-szék and zab-szék in 2000. despite fig. 6 change and instability in the region of the upper kiskunság lakes joeg i/3-4 evaluation of changes and instability of water content using remote sensing methods… 13 the favourable precipitation conditions characteristic of the first half of 2001, the extension of inundated areas was only half as much as a year earlier on the basis of the photo taken in june. twenty-three per cent of the area is changeable from the point of view of water content. the disappearance of kis-rét is the most striking during the examination of the lakes. it was almost the largest lake in 2000, but it dried up very fast, and there are no data for the year 2002. co-spatiality of change and instability in the change analysis those areas are more significant which turn out to be stable in the instability analysis (fig. 6). the exact registration of change is more difficult in unstable areas, and processes, endangering even the more permanent phenomena, could be more dangerous. those areas can also be highlighted, which are depicted as marshes, lakes, wetlands on a map, but appear as light areas on the instability map. it indicates a greater sensibility, a more possible drying up, and it can question the long-term processes. aridification is represented by the shades of grey concerning both the whole area and the patches. the categorization of certain changes is difficult by the comparison of the dates of several long-term changes; therefore, the created result map was classified from specific, optimistic and pessimistic viewpoints. the rate of aridification is 28% according to the pessimistic viewpoint, while it is 13% according to the optimistic one. if the spatiality of instability is also taken into account, even the very unstable areas, formerly classified as aridification areas, can be delineated. according to our analysis, these surfaces are probably not becoming more and more arid, they are only unstable. on fig. 6 a map representing the optimistic point of view can be seen, which is specified according to the aforementioned principle, and its value for the rate of aridification decreased from 13% to 11%. the value of our pessimistic analysis changed to 22%. conclusion the mapping and monitoring of large areas of wetlands can be solved only by remote sensing methods. besides the surveys carried out for different years, the short-term, high time-resolution analyses are also needed for the study of long-term change. a short but a geographically very interesting period has been studied on the basis of multispectral images, which made it possible to study and interpret the hydrological balance of the lakes, and the effect of the unfavourable climatic conditions. by the examination of wetlands the drying up and the aridification can be well evaluated. the positive effect of the increasing precipitation observable from the end of the 1990s is not general. the majority of the former wetlands can only partially regenerate, mostly as a periodic marsh. by the current change in a human lifetime an area can be prognosticated in upper kiskunság lakes which is drying up, but is periodically activated in rainy weather. a possible shift of the range of values relevant to the water-level changes can be determined by a periodical instability mapping in the more and more arid great hungarian plain. this is going to be taken into consideration in our change analysis ending in the near future. acknowledgement the research was supported by the project “development of an excess water-info system” (economic operative program: gop 1.1.1 08 / 1 -2008 – 0025) and by the hungarian scientific research fund (otka pd 78349). references barna gy. 2008. talajés vegetációváltozások egy dél-alföldi mintaterületen. in: orosz z. – szabó v. – molnár g. – fazekas i. 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stålhammar and pedersen, 2017). the categories of ces have evolved significantly from the original idea: at first it recognized merely recreation and culture, but now its meaning broadened in the consolidated framework developed by the millennium ecosystem assessment (ma) in 2008 (fisher and turner, 2008). ces categories are spiritual and religious, recreation and ecotourism, aesthetic, inspirational, sense of place, cultural heritage and educational (tratalos et al., 2016; ament et al., 2017). recreation and ecotourism can be defined as the practicing of leisure activities during one’s spare time: if people participate in activity near their home or community, it is considered recreation, such as hunting, fishing, riding bikes, mountain climbing etc. however, if these activities are further away, and people must travel some distance to participate in them, they are often described as ecotourism such as visiting historical areas to study, admire and enjoy scenery, plants, animals, and cultural attractions. participating in recreational activities is of great importance for maintaining mental and physical health of individuals, families and communities (tratalos et al., 2016; stålhammar and pedersen, 2017). a positive relationship was found between human health and green areas in recent studies, supporting the idea that parks, green areas, and their facilities affect public health positively (schneider and lorencová, 2015; doğu and çamaşırcıoğlu, 2016). sustainable planning represents the idea that local people should live within the capacity of their environment to support them, which becomes essential, especially in the planning process for new services. (senes and toccolini, 1998). the high population density living and working in the same area leads to the degradation of the ecosystem environment and the surrounding area (fung and wong, 2007). high recreational use on the land can significantly affect the natural and cultural value of the land and surrounding area. as a result, environmental and social values can be degraded in some areas, especially where there are limited appropriate natural and cultural areas near urban or areas with high population density (manning et al., 2011). according to the sustainability of the environment, different kinds of concepts have to be considered, such as carrying capacity, landscape scenery, sensitivity to natural and cultural values, and regular maintenance. for achieving the sustainability of recreation benefits for present and future generations, it is necessary to address and work toward a sustainable balance between environmental, social, and economic conditions. https://doi.org/10.14232/jengeo-2008-43946 asmaa.haggag@aswu.edu.eg 12 abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. sustainable land-use planning requires an in-depth analysis of the existing resources' localization, features, sensitivity to development, and an understanding of development characteristics and resource needs (senes and toccolini, 1998; leung et al., 2008; mccool, 1994). there are different kind of spatial and non-spatial criteria utilized in the evaluation process of different kind of ces, especially recreation services. for example, dağıstanlı et al. (2018) addressed criteria, namely landuse type, distance from water surface, natural and cultural areas, distance from residential areas, distance from transportation or roads, flora cover density, erosion, slope, and their sub-criteria and weightings, which are typically employed in the evaluation of land for recreational suitability, in the compilation of information on the study area. nahuelhual et al. (2013) utilized all of the singular natural resources, scenic beauty, accessibility, tourism attraction capacity, and tourism use aptitude, as land evaluation criteria for recreation service. bunruamkaew and murayama (2011) determined criteria for selecting a region as a tourism area. these criteria at the macro-level include two main categories, environmental and socioeconomic features. each of the mentioned categories consists of many sub-criteria that have significant importance in tourism land capability evaluation of the land (bunruamkaew and murayama, 2011; dağıstanlı, et al., 2018). environmental features include physical and biological criteria. physical criteria, including climate, topography, geology, and pedology, are placed at the fourth level (zarkesh et al., 2011). biological criteria in the fourth level contain fauna and flora, and two subcriteria land cover density and animal distribution. there are several factors in the economic and social characteristics including land uses buffers and distances. carrying capacity of the landscape also include as a social-economic criterion in the proposed evaluation criteria of recreation activities: how much use can be accommodated in the recreational site before the quality of the visitor experience is degraded to an unacceptable degree? so, the carrying capacity is an indicator/criterion which evaluate the quality or the efficiency of the recreation services. for example, cupul-magana and rodriguez-troncoso (2017) argue that using the carrying capacity concept in a recreation area may generate a satisfactory experience for the recreation with an acceptable or minimum impact on the resource of the natural and cultural area. atanga (2019) proposed a method to calculate the recreational carrying capacity by calculating the number of visitors per day in a recreational area or recreational facility for a certain period of time. some of mentioned criteria defined in the articles are considered for my study. land suitability analysis is the process of predicting the potential use of land on the basis of its attributes. decisions on land use have always been part of the evolution of human society. in our crowded and complex world, the decisions on land use are frequently brought about by the process of land use planning by the land evaluation (dağıstanlı et al., 2018). such planning takes place in all parts of the world, including the middle east countries such as egypt (bunruamkaew and murayama, 2011). as gis-based multi-criteria decision analysis (mcda) became one of the most useful methods for spatial planning and management (dağıstanlı et al., 2018), thus combining gis and mcda is a powerful approach for land suitability assessments. gis techniques and procedures have an important role to play in analyzing spatial decision problems (lee et al., 2010). indeed, gis is often recognized as a spatial decision support system. on the other hand, the analytic hierarchy process (ahp), introduced by saaty and vargas (1980), is an effective tool for dealing with complex decision making, and may aid the decision maker to set priorities and make the best decision. in addition, the ahp incorporates a useful technique for checking the consistency of the decision maker’s evaluations, thus reducing the bias in the decision-making process (ahmed et al., 2016). there are many studies in the literature that integrates the gis applications and mcda models. one of the most remarkable features of the gis-mcda method is the wide range of decision and management situations in which they have been applied. major application areas include: environmental planning and management (e.g. conroy and peterson, 2013; mosadeghi et al., 2013; mustajoki and marttunen, 2017), recreational and ecotourism planning and management (e.g. olaniyi et al., 2018; zabihi et al., 2020), urban and regional planning (e.g. mosadeghi et al., 2015; simwanda et al., 2020), waste management (e.g. coban et al., 2018), outdoor recreation planning (e.g. chow et al., 2014; dağıstanlı et al., 2018), agriculture and forestry (colantoni et al., 2016). this research attempts to evaluate environmental and recreational capabilities in aswan city (egypt) as a case studyusing a mcda which includes weighted linear combination (wlc), and the analytic hierarchy process (ahp). for scrutinizing the criteria selected from the literature, we used weighted pairwise comparisons. data study area aswan is located at the southern tip of egypt and is the state capital of the aswan governorate (fig. 1), and the city is considered as the southern gate to africa. aswan’s population is almost about 900,000, and its area about 35,7 km2. aswan is considered as one of the best tourist destinations around the world, because of its tourist distinctive features, especially in winter. in addition, the moderate and dry climate is the most important feature of aswan city, because of its location on the nile east bank. during the summer, average temperature is above 23°c, while in the winter it remains above 8°c. so, aswan city is considered an international winter resort. moreover, it has many different archaeological and historical attractive sites, so, it is known as one of the best open museums that date back to various ages and spread all over the city. aswan is a busy market and tourist center, and it is considered beside luxor city as a vast tourism source in egypt. furthermore, the city has many natural and cultural attractions and ancient pharaonic civilizations, including pharaonic, islamic, and nubian. the most important natural and cultural attraction sites are the upper dam, the abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. 13 tabiya mosque, the nile museum, the princess ferial park, the west suhail area, the nile islands, and the twin temple of abu simbel (fig. 2). moreover, aswan has some tourist attraction sites located on the nile banks, and they are considered as appropriate sites where visitors can practice the hobby of swimming and sailing boats. data sources different type of data sources was utilized in the present study (table 1). firstly, the primary data have been assembled through online questionnaires answered by experts in the related fields of study to identify criteria/indicators that are important for land evaluating of recreation service along with statistical data. secondary, layers displaying land use/cover and vegetation density have been created utilizing a landsat satellite image (landsat 8 etm+2011), and the road layer has been downloaded from esri. finally, other data such as attractive sites and current recreation and tourism sites have been collected by using field survey data applying global positioning system (gps). an online questionnaire has been established to order the chosen res evaluation sub-criteria based on their importance. only experts in urban planning, recreation, and tourism have been involved in this questionnaire. altogether 200 questionnaire forms had been sent to experts, and all criteria gave a rating value from 1 “least important” to 9 “extremely important”. the obtained sub-criteria were classified into three main criteria: environmental, social, and economic criteria. a total of 53 respondents ranging from decision-makers, fig. 1 location of the study area fig. 2 natural and cultural attraction sites at aswan city 14 abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. academicians, landscape and urban planners with 5–15 years in landscape and urban planning experience were involved in this survey. the stratified random sampling method was chosen, which comprises landscape experts, academicians, urban planning and design experts, architectures, and others. to ensure a better response, the survey forms were distributed by e-mail for 200 people. moreover, part of the questionnaire was also sent by google accounts. altogether, 41 questionnaires were completed by 11 landscape experts, 10 architects, 15 urban planners and designers, and the remained number classified as others. the number of participants who started with the assessment and ranking of the evaluation criteria was just 53, but only 41 evaluated the complete set of 12 criteria questions. the participation/response rate was approximately 26% (the number of people who assessed at least one question compared to the total number of people received the online surveys). methods procedure the technical procedure of the multi-criteria evaluation (mce) model of land evaluating of current recreation service in aswan city is illustrated on figure 3. gis database development of this study was made by using recreation service spatial evaluating indicators/criteria and display each spatial indicator in maps. however, ahp is a methodical method helping decision-makers and urban planners in making better decisions to solve urban planning problems based on different priorities. thus, in this study, ahp was used to calculate land evaluation indicators' weight. in order to produce a land evaluation model of recreation service four main steps was followed (fig. 3). first, based on the literature review, spatial land evaluation indicators were collected for the assessment process. they were transferred based on their type to main indicators/criteria and factors which can be used as input layer in the mce model. in the second step land evaluation indicators/criteria priority were determined by considering expert opinion and calculate indicators/criteria weights by using the ahp method to be involved in the evaluation process. thirdly, indicators/criteria maps were created using proper spatial analysis techniques in arcgis environment such as distance, reclassify, and raster calculation for applying ndvi analysis. then a land evaluation map was produced by overlaying all indicators/criteria maps and weights by using the weighted indicators overlay tool in arcgis environment. finally, after producing a land evaluation map for recreation service, the current state of recreation service in aswan city was evaluated based on the produced map. utilized land evaluation criteria according to the literature review, different kind of spatial and non-spatial criteria have been collected to achieve the sustainable planning of recreation service (table 2). however, only spatial criteria should be considered when conducting a land evaluation of recreation service (table 3). the recreation service land evaluation criteria may differ from one region to another based on circumstances and local conditions (zoderer et al., 2016; clemente et al., 2019). in the present study, a various criterion has been analyzed to conduct a land evaluation of recreation service in the study area. therefore, a number of studies were reviewed to gather the related evaluation criteria (casado-arzuaga et al., 2014; sun et al., 2019). the utilized criteria in the land evaluation of recreation service were (1) type of land cover/use; (2) distance from water bodies; (3) distance from attractive sites; (4) distance from current residential area; (5) distance from roads; (6) vegetation density; (7) table 1 list of collected data and their source data type of data utilized for creating source aswan boundary file vector clip indicators maps gaup egypt landsat satellite image raster land cover/use landsat8 (bands 2,3,4,5,6,7) etm+ 2011 digital elevation model (dem) raster slope usgs natural and cultural attractions vector distance from attractive sites field survey with gps road map vector distance from road and transportation road layer, esri water bodies map vector distance from water bodies gaup egypt pollution map vector distance from active pollution points gaup egypt vegetation cover raster vegetation density ndvi index world soil map vector soil erosion/loss fao dsmw current recreation and tourism site vector to evaluate current rts field survey with gps abbreviations: gaup (general authority for urban planning); usgs (u.s. geological survey); dsmw (digital soil map of the world) abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. 15 fig. 3 recreation and tourism services land evaluation process table 2 recreation service evaluation criteria classification evaluation criteria sub-criteria spatial sub-criteria non-spatial sub-criteria utilized sub-criteria environmental criteria biodiversity vegetation √ √ availability soil erosion √ √ comfort water bodies √ √ pollution active pollution points √ √ topography elevation √ √ social criteria accessibility distance from residential areas distance from attractive sites distance from road √ √ √ √ √ √ security number of threats √ compatibility sense of satisfaction sense of happiness sense of care with the place √ √ √ economic criteria utility travel costs willingness to pay (wtp) √ √ efficiency landscape settings photographs accommodation carrying capacity population density √ √ √ √ √ site's price site location √ surrounding area land cover/use viewpoint landscape aesthetics √ √ √ √ 16 abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. slope; (8) distance from active pollution points; and (9) soil erosion/loss. the criteria and sub-criteria importance were chosen and ordered according to the literature review and experts’ opinions. collected criteria for the land evaluation process should be comprehensive and measurable (zarkesh et al., 2011). in this process, data of all selected criteria were displayed and analyzed individually. finally, all criteria displayed on maps were overlaid to produce the recreation service land evaluation map. thus, to produce a land evaluation map, the collected evaluation criteria can be integrated into the mce model, and these criteria have to be transferred to layers on arcgis environment to converted to maps (table 3, fig. 4). evaluation criteria weight calculation the ahp is one of the most extended mce techniques. this method provides a structural basis for quantifying the comparison of decision elements and criteria in a pairwise technique (chandio et al., 2013; li et al., 2018). therefore, in the present study, we asked experts about their opinion to rate land evaluation criteria of recreation table 3 recreation and tourism services site evaluation criteria/indicators details and data types criteria/indicators layer type spatial analysis vegetation density raster layer ndvi analysis (band 4,5) elevation raster layer slope tool land cover/use raster layer composite (band 2-7)-classification tool water bodies shape file-polygon-converted to raster distance tool (cell 30) attractive sites shape file-pointsconverted to raster distance tool (cell 30) residential areas shape file-polygonconverted to raster distance tool (cell 30) road or transportation shape file-polylineconverted to raster distance tool (cell 30) pollution points shape file-pointsconverted to raster distance tool (cell 30) soil erosion/loss vector layer using land use and slope raster calculator fig.4 recreation and tourism services land evaluation indicators maps abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. 17 service based on their importance. and then each criteria weight was calculated by considering the priority suggestions from experts by using the ahp method. based on the properties of reciprocal matrices, the consistency ratio (cr) index can be calculated to ensure the credibility of the relative significance used. 𝐶𝑅 = 𝐶𝐼/𝑅𝐼 (1) where c1 is consistency index and r1 is random inconsistency index. in general, if the cr index is ≤10%, then the degree of consistency is considered constant and acceptable. but if cr is larger than 10%, then there are inconsistencies in the assessment process, and the results should not be used in the evaluation process and not acceptable, and the evaluation process has to be revised (bunruamkaew and murayama, 2011). land evaluation criteria weights have been calculated by using a pairwise comparison matrix. for every two criteria, the pair-wise comparison matrix was applied by utilizing a nine-point scale. the nine-point scale includes 9, 8, 7, ..., 1/7, 1/8, 1/9, where 9 means extreme preference, 7 means very strong preference, 5 means strong preference, and so on down to 1, which means no preference (table 4). the pairwise comparison matrix allows the evaluation of the contribution of every criterion, therefore it simplifies the process of decision-making. the consistency index (ci) of the matrix was calculated as: 𝐶𝐼 = (𝑚𝑎𝑥 − 𝑛)/(𝑛 − 1) (2) where ci is the consistency index, λmax is the largest eigenvalue of the matrix, and n is the number of criteria. land evaluation map creation in the present study, the recreation and tourism land evaluation map were produced, based on the weighted linear combination (wlc) of each selected indicator’s suitability score by using equation 3. to calculate the recreation and tourism land evaluation indicator weights and identify the importance rate for all indicators, the ahp method has been applied. the land suitability score “se” for each site in the study area was calculated from the wlc of the land suitability score gained from each involved indicator. by using the wlc procedure and raster calculator tool in arcgis, the recreation service land suitability evaluation model has been established by using the following equation: 𝑆𝐸 = ∑ 𝑊𝑖𝑋𝑖𝑛𝑖−1 (3) where se is the value of the recreation service suitability evaluation; n is the total criteria number; wi is the weight result of each indicator i, and xi is the suitability map for each involved indicator in our analysis. like the indicator map, the land evaluation map of recreation service was also divided into four classes and these classes were given the numerical values (1-4), which represent most-suitable (s1), suitable (s2), lowsuitability (s3), and not-suitable (n), respectively. results criteria order and weights based on the expert’s questionnaire analysis, first of all, experts have scored both the distance from attractive points and distance from residential areas criteria as the most important factors to evaluate recreation service, followed by distance from water bodies. in the contrast, all the remained indicators were received the lowest importance compared to previous indicators. the previous results ensure the rank of the land evaluation criteria of recreation service from the most important to the least important, as it follows: distance from attractive points; distance from residential areas; distance from water bodies; soil erosion; distance from active pollution point; distance from road and transportation; vegetation density; slope; and type of land use/cover (table 5). based on the expert order of recreation and tourism land evaluation criteria, these criteria' weights have been calculated by using the ahp method. table 5 shows the importance and weights of recreation and tourism land evaluation criteria. based on the ahp result, the criterion distance from attractive points received the highest weight (34.00%) with a consistency ratio (cr) of 0.78, followed by distance from residential areas and distance from water bodies criterion (23.20% and 14.10% respectively) with cr of 1.19 and 1.45, while all the remained land evaluation criterion received the least weight (range from 7.10% to 2.70%). table 5 presents the attribute of recreation service land evaluation criteria in aswan city and indicate the percentage of its weight with consistency ratio (cr) for each evaluation criterion. the consistency ratio of the evaluation process was calculated for recreation service evaluation cr iteria. it was found less than 0.1 (0.077), which means our evaluation process is constant and acceptable to can be used in the suitability evaluation process in aswan city. the pair-wise comparison matrix for every two indicators and computation of cr are given in table 5. evaluation criteria classification the specified land evaluation system was used to reclassify recreation service land evaluation criteria in line with the degree of effect on the land evaluation table 4 the comparison scale in the ahp method (saaty and vargas 1980) scale of importance definition 1 equal importance 3 slight importance 5 strong importance 7 demostrated importance 9 absolute importance 2, 4, 6, 8 intermediate values 18 abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. process. each criterion was categorized, and their land evaluation scores were presented in the standardized map format. the land use/cover classes in the study area were categorized into these four evaluation classes. they are as follows: most-suitable (grassland), suitable (bare land), low-suitable (sand land), and not suitable (built-in) for recreation service (table 6, fig. 5). table 7 illustrates that both bare land area and built-in area cover more than half of the total area of the case study (35.12% and 27.54% respectively), while sand land area covers around a fifth of aswan city accounting for 17.55% of the total area. however, both grassland and water bodies cover almost the same area, 9.92% and 9.87% respectively. consequently, the total land evaluation score from each factor was pulled together to calculate the land evaluation map for recreation service by using equation 3. the evaluation classes are defined as: (1) most-suitable (ms) class: it indicates a land parcel of high suitable that is located a considerable distance from natural and culture attractive sites which is close to residential areas and water sources and easy access to from the towns and that is table 5 evaluation indicators weight and ranks by using pair-wise comparison. ci: consistency index; ri: random consistency index; cr: consistency ratio. criteria dist. wb dist. ap dist. cpp dist. r$t dist. ra lu type slope veg. density soil erosion weight (%) consistency index priority dist. water bodies (wb) 1.00 3.00 5.00 7.00 5.00 0.20 3.00 9.00 0.33 14.10% 1.45 3 dist. attractive points (ap) 0.33 1.00 3.00 5.00 0.33 0.11 3.00 0.33 0.14 5.20% 1.39 6 dist. active pollution points (cpp) 0.20 0.33 1.00 3.00 0.33 0.14 5.00 0.20 0.11 4.20% 1.42 7 dist. road and transportation (r$t) 0.14 0.20 0.33 1.00 0.20 0.14 3.00 0.20 0.11 2.70% 1.13 9 dist. residential area (ra) 0.20 3.00 3.00 5.00 1.00 0.11 3.00 0.33 0.14 6.10% 1.61 5 land use (lu) type 5.00 9.00 7.00 7.00 9.00 1.00 9.00 7.00 3.00 34.00% 0.78 1 slope 0.33 0.33 0.20 0.33 0.33 0.11 1.00 3.67 0.14 3.40% 1.16 8 vegetation density 0.11 3.00 5.00 5.00 3.00 0.14 0.27 1.00 0.14 7.10% 2.03 4 soil erosion 3.00 7.00 9.00 9.00 7.00 0.33 7.00 7.00 1.00 23.20% 1.19 2 ci= 11.04, ri = 1.45 cr = 7.70% <10% acceptable table 6 site evaluation criteria reclassification dist. from water bodies (m) dist. from attractive points (m) dist. from active pollution points (m) classes ler classes ler classes ler 0-300 ms (4) 0-250 ms (4) 0-700 ns (1) 301-700 s (3) 251-500 s (3) >700 ms (4) 701-1000 ls (2) 501-700 ls (2) >1001 ns (1) >701 ns (1) dist. road and transportation (m) dist. residential area (m) land use type classes ler classes ler classes ler 0-500 ms (4) 0-500 ms (4) grassland ms (4) 501-1000 s (3) 501-1000 s (3) bare land s (3) 1001-2000 ls (2) 1001-2000 ls (2) sand land ls (2) >2001 ns (1) >2001 ns (1) built-in ns (1) slope (%) vegetation density (%) soil erosion classes ler classes ler classes ler 0-6 ms (4) 0-10 ns (1) high ns (1) 7-20 s (3) 11-40 ls (2) moderate ls (2) 21-30 ls (2) 41-70 s (3) low s (3) >30 ns (1) >71 ms (4) very low ms (4) ler: land evaluation rate abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. 19 suitable for developing recreation service in aswan city. (2) suitable (s) class: it indicates a land parcel that fulfills many land evaluation criteria that may optimize the existing recreation and tourism resources to properly develop and promote a mass kind of recreation service and that could provide various opportunities for creating recreation service services in these sites with some modification. (3) low-suitable (ls) class: it is an intermediate level between the unsuitable and suitable classes. (4) not-suitable (ns) class: it indicates a land parcel that relatively not fulfills many land evaluation criteria that is not suitable for developing recreation services in the study area which requires strict urban regulations. land evaluation map we performed the land evaluation of recreation services by utilizing the spatial analysis tools and a comprehensive overlay analysis of arcgis on each evaluation criteria to obtain the final evaluation value. like land evaluation criteria, the values of the land evaluation map were divided into four classes: not suitable (n), low-suitable (s3), suitable (s2), and mostsuitable (s1) (fig. 5). overall, the results indicate that the spatial distribution of recreation and tourism services in aswan city is high in the middle of the area, especially along the nile river, and low in the east and southwest. based on the land evaluation map, the mostsuitable (s1) area is located in the middle of the study area and about 2892.2 ha, accounting for 25% of the study area. most of these areas are water bodies like lakes and rivers, and areas with high green coverage. while the suitable area (s2) is 4523.5 ha large, accounting for 39% of the case study area. it contains built-in areas and urban areas surrounding by green space. the less-suitable (s3) area is 3029.0 ha large, accounting for 26% of the study area, and most of these areas are characterized by low-density urban construction land with serious ecological and environmental problems, like areas close to active pollution sites. the not-suitable area has a size of 1200.6 ha, accounting for 10 % of the study area. it is mainly the area that has a low density of built -in and urban construction and population, such as desert and sand lands. therefore, it is necessary to create new recreation service for all un-covered spaces with recreation sites as far as possible, to improve the table 7 type of land use/cover areas type of land use/cover area (ha) area (%) grassland 1161.9 9.9% bare land 4113.0 35.1% sandy surface 2054.7 17.5% built-in 3224.6 27.5% river (water) 1155.8 9.8% total 11710.3 100% fig. 5 land use classification map fig. 6 recreation and tourism services land evaluation map 20 abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. distribution of these kinds of services in the sand and bare land areas and motivating the urban planning extension in those areas. based on our evaluation of the study area, we concluded that the most suitable lands for recreation service planning are the sites where the environmental and ecological problems, like pollution, are not appropriate, but high vegetation density and green space is urgently needed. with regards to the analyzed results of the land evaluation process, the most suitable lands for recreation service are mainly distributed in the areas which are along both banks of the nile river. table 8 indicates and compares the land suitability classes of recreation service in aswan city in terms of index value and area. whenever the land suitability index value increases, the potential land suitability for developing recreation service raise. discussion land evaluation of recreational facilities is the most effective approach before we began the planning and outlining process (li et al., 2018). hence, it is necessary to consider many spatial criteria for evaluating the suitability of study area land for creati ng and assessing the current recreation and tourism facilities before considering public opinions and demands, and also planning needs in the recreation and tourism planning process (ebrahimi et al., 2019). land suitability evaluation of recreational and tourism services is essential when planning and developing any region effectively. moreover, the land evaluation before the planning process will serve to prevent wastage of financial and human resources. in this study, questionnaires were used to rank and weight the recreational and tourism evaluation criteria based on their importance in the planning process, and then the integration between gis and mce method was used for land evaluation of current recreation and tourism services and indicate the suitable lands for potential services. through this gis-mce approach, an effective framework for land evaluation of this kind of services was presented, the selection of evaluation indicators, and the determination of a suitable weight for each indicator had a direct influence on the final land evaluation map results (ebrahimi et al., 2019). the results revealed that there are five categories of land evaluation maps of recreation and tourism including areas with very high spatial suitability, areas with high spatial suitability, areas with moderate spatial suitability, areas with low spatial suitability, and areas with very low spatial suitability. and these suitability categories were utilized in the evaluation of the current state of existing recreation and tourism sites which is called land evaluation in aswan city. moreover, this study also supports the recommendations of establishing other recreation and tourism activities in order to allow expansion of the urban masses of aswan city and ensuring all study area covered with recreation and tourism facilities and motivate the urban planning development of these kinds of services. in our study, distance from residential areas, water bodies, road and transportation, and natural and cultural attractions were determined with distance analysis in gis and all of the mentioned criteria are classified to four grads based on their importance, and slope classification was obtained from the digital elevation model (dem). furthermore, soil loss/erosion indicator was created by classes were taken from world digital soil map (wdsm). distance from natural and cultural attractive sites is an important factor in land suitability evaluation of recreation and tourism services because it plays an essential role in how the public preferences are interacting with the natural and cultural attractive sites. moreover, type of land use/cover and vegetation density are necessary as well for urban development of current and future recreation activities. besides, some studies have addressed the connection between the distance to water sources criterion and how often locals use recreation service services. due to reach the recreation service services area that has natural and culture attractive sites, easy access should be taken into our consideration. in addition, for different recreational activities such as swimming, walking, and running, there are many important indicators that have to be used to identify the suitable sites for creating new recreation activities such as soil loss/erosion, slope, and distance to roads. the benefits of using the ahp method in solving site suitability decision problems which is a multi criteria decision process integrated into gis which used in the land suitability evaluation process and it was expressed by chandio et al. (2013). moreover, according to many studies, such as aklıbaşında and bulut (2014), this methodological approach has other advantages like increasing the accuracy of used data and contributing to the planning process efficiency and allowing a quick process of a large amount of spatial information particularly for analyzing a large area. in our study, the ahp method was utilized to conduct the pair-wise comparisons for many different factors by applying ahp method equations (e.g. equations 1 -3) table 8 utilized classification index for land evaluation map definition classes index value area (ha) area (%) not suitable n <1.9 1200.7 10 % less suitable s3 1.9-2.5 3029.0 26% suitable s2 2.5-3 4523.5 39% most suitable s1 >3 2892.2 25% total 11645.4 100% abualhagag and valánszki 2022 / journal of environmental geography 15 (1–4), 11–22. 21 in excel sheets. the normalized weights for each recreation service land evaluation criterion were calculated by utilizing a pair-wise comparison matrix (table 5). by asking experts to order the land evaluation criteria based on their importance for producing recreation and ecotourism services suitability map, the pair-wise comparison matrix was calculated. furthermore, a standardized weight of each criterion was calculated from the pair-wise comparison matrix, allowing the assignment of weighting to each criterion by using equation 3. the highest value was for distance from attractive natural and cultural sites and the lowest was for the type of land use/cover criterion. the land evaluation of the study area determined that sites located around water bodies and have natural and cultural attractive points are the most. therefore, aswan city has a great opportunity for developing suitable lands for recreation and tourism activities. however, land that is not close to both water bodies or roads and transportation and that has just a few attractive sites been mainly not suitable for recreation and ecotourism activities. furthermore, there are some sites within our study area that are close to active pollution points and located on steep slopes and thus are also not suitable for recreation and ecotourism sites. in general, our results indicate that aswan city has good natural and cultural resources for developing and supporting recreation and ecotourism services in the future. because more than half of the study area consider suitable and most suitable areas and most of these areas include sites that have distance from active pollution points more than 700 m, distance from all of the residential area, water bodies, attractive points, and public transportation less than 1000, 700, 500, and 100 m respectively, with a slope less than 20% and lands with low and very low soil erosion. the investigation of the present study shows that aswan city has a great potential opportunity for successful urban planning and improvement of current and future areas for many different types of recreational and ectourism activities. moreover, aswan has some site which locates on the nile banks, which is considered as tourist attraction sites, and it considers appropriate site where tourist can practice the hobby of swimming and sailing boats also. in addition to natural and cultural attraction destinations, tourist travel to aswan to visit the islands of plants like el-nabatat island, museums like the nile museum and nubian museum, and temples on the islands of the middle of the river like the temple of philae, and other areas suitable for walking, jogging and running, around the river. conclusion the recreation and ecotourism land evaluation process used in this study demonstrated how mce approaches can be incorporated into the gis planning and decision process to evaluate the current state of recreation and ecotourism facilities based on spatial criteria. additionally, combining mce and gis contributed to a more robust understanding of current recreation site distribution patterns and suitable areas for potential recreation and ecotourism activities in the future. moreover, this study provides a foundation for planners and decision-makers to continually develop and improve the urban planning approaches for future recreation and ecotourism facilities sites. furthermore, this study was able to identify, weigh, and rank the evaluation spatial criteria of land evaluation for recreation and ecotourism services in aswan city based on different kinds of site evaluation criteria. land use/land cover and visibility are considered to be the highest-ranked indicators, respectively. our study area constitutes one of the main recreations and ecotourism destinations around the world. thus, land evaluation of recreation and ecotourism services is a multi-criteria decision problem, which needs to meet the functional planning requirements and indicators. the evaluation methodology utilized in this study that is conducted for land evaluation of recreation and ecotourism services can also be applied to other land evaluation process. gis-based ahp as an mce approach is applied in this evaluation study. the main benefit of this evaluation approach is that it can be applied quickly using the data processing in arcgis environment. thus, the concluded results of the present study will be useful with gis-based land evaluation and suitability analysis modeling in land-use development and assessment plans. of recreation and ecotourism sites in the future. moreover, this study also supports the recommendations of establishing other recreation and tourism activities in order to allow expansion of the urban masses of aswan city and ensuring all study area covered with recreation and ecotourism facilities and motivate the urban planning development of these kinds of services. therefore, for future planning, it is important to make an ecological and environmental connection between both current recreation and ecotourism sites and potential sites and cultural and natural attraction sites in the study area. on the other hand, planner and decision-makers could be better consider these mapping indicators/criteria when planning for new sites for recreation and ecotourism activities in aswan city. it would be better to integrate the natural and cultural attractive sites in aswan city and the suggested or potential recreation and tourism sites and consider the land evaluation criteria/indicators which effect on the suitability of the planned sites. acknowledment the researcher “asmaa abualhagag ahmed” is funded by a full scholarship (36002) from the ministry of higher education of the arab republic of egypt, and the stipendium hungaricum scholarship. references ahmed, a.h., mahmoud, h., aly, a.m.m. 2016. site suitability evaluation for sustainable distribution of hospital using spatial information technologies and ahp: a case study of upper egypt, aswan city. journal of geographic information system 8(5), 578–594. doi: 10.4236/jgis.2016.85048 aklıbaşında, m., bulut, y. 2014. analysis of 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10.1016/j.landusepol.2016.05.004 http://dx.doi.org/10.1007/s10661-014-3814-6 http://dx.doi.org/10.1111/conl.12283 http://dx.doi.org/10.30892/gtg.25204-362 http://dx.doi.org/10.1016/j.sbspro.2011.07.02 http://dx.doi.org/10.1007/s10980-013-9945-2 http://dx.doi.org/10.1007/s12517-012-0568-8 http://dx.doi.org/10.1080/15568318.2011.654177 http://dx.doi.org/10.1016/j.ecolind.2018.08.043 http://dx.doi.org/10.1016/j.jclepro.2018.01.130 http://dx.doi.org/10.1016/j.landusepol.2015.09.012 http://dx.doi.org/10.1002/9781118506196 http://dx.doi.org/10.1016/j.apgeog.2017.08.021 http://dx.doi.org/10.1007/s12517-018-3856-0 http://dx.doi.org/10.9790/6737-03030611 http://dx.doi.org/10.1007/s41685-019-00123 http://dx.doi.org/10.1007/s41685-019-00123 http://dx.doi.org/10.1016/j.biocon.2008.02.019 http://dx.doi.org/10.1080/10106040701207332 http://dx.doi.org/10.1080/09669581003690478 http://dx.doi.org/10.1079/9781845934705.0019 http://dx.doi.org/10.3390/su10082656 http://dx.doi.org/10.1080/02508281.1994.11014708 http://dx.doi.org/10.1080/09640568.2012.717886 http://dx.doi.org/10.1016/j.compenvurbsys.2014.10.001 http://dx.doi.org/10.1016/j.envsoft.2017.02.026 http://dx.doi.org/10.1016/j.apgeog.2012.12.004 http://dx.doi.org/10.1080/13032917.2018.1486329 http://dx.doi.org/10.11118/actaun201563051555 http://dx.doi.org/10.1016/s0169-2046(97)00064-9 http://dx.doi.org/10.1016/j.landusepol.2019.104441 http://dx.doi.org/10.1016/j.ecoser.2017.05.010 http://dx.doi.org/10.1016/j.ufug.2018.11.012 http://dx.doi.org/10.1016/j.ecolind.2015.03.040 http://dx.doi.org/10.1016/j.tmp.2020.100726 http://dx.doi.org/10.1016/j.landusepol.2016.05.004 introduction data study area data sources methods procedure utilized land evaluation criteria evaluation criteria weight calculation land evaluation map creation results criteria order and weights land evaluation map discussion conclusion acknowledment references journal of environmental geography journal of environmental geography 9 (1–2), 23–30. doi: 10.1515/jengeo-2016-0004 issn: 2060-467x satellite based analysis of surface urban heat island intensity orsolya gémes, zalán tobak*, boudewijn van leeuwen department of physical geography and geoinformatics, university of szeged, h-6722, egyetem u. 2-6, hungary *corresponding author, e-mail: tobak@geo.u-szeged.hu research article, received 1 may 2016, accepted 1 june 2016 abstract the most obvious characteristics of urban climate are higher air and surface temperatures compared to rural areas and large spatial variation of meteorological parameters within the city. this research examines the long term and seasonal development of urban surface temperature using satellite data during a period of 30 years and within a year. the medium resolution landsat data were (pre)processed using open source tools. besides the analysis of the long term and seasonal changes in land surface temperature within a city, also its relationship with changes in the vegetation cover was investigated. different urban districts and local climate zones showed varying strength of correlation. the temperature difference between urban surfaces and surroundings is defined as surface urban heat island (suhi). its development shows remarkable seasonal and spatial anomalies. the satellite images can be applied to visualize and analyze the suhi, although they were not collected at midday and early afternoon, when the phenomenon is normally at its maximum. the applied methodology is based on free data and software and requires minimal user interaction. using the results new urban developments (new built up and green areas) can be planned, that help mitigate the negative effects of urban climate. keywords: urban lst, urban heat island, landsat introduction although, fifty three percent of the world's population lives in cities, according to the estimations only 3% of the continents is urban area (world bank, 2014). this relatively small area is intensively used and continuously affects its inhabitants by providing them a dynamically changing residential environment. the climate of the horizontally and vertically diverse urban surface is influenced by several factors on macro and meso (e.g. climate, elevation, relief), as well as local level. local modifying factors, not active in non urban areas are (1) the generally higher specific heat and low albedo of anthropogenic surfaces, (2) modified water regime resulting in lower air humidity, (3) the special surface geometry modifying the flow conditions, (4) the periodical heat surplus (due to heating, traffic or industry) and (5) the increased atmospheric aerosol concentration (unger, 1996). on meso level the impact of urban surfaces can be detected up to 9-11km (urban boundary layer – ubl), and local micro-level processes have effects up to the average roof-top level (urban canopy layer – ucl) (oke, 1976). the total energy balance of urban areas is similar to the rural areas, however, there are differences in the ratio of shortwave and longwave radiation. due to the high aerosol concentration the incoming direct, diffuse and atmospherically reflected shortwave radiation is low, and the shortwave radiation reflected from the surface is also low due to the low albedo. the warmer surfaces result in higher longwave radiation, furthermore air pollution increases the reflected and diffuse longwave radiation (unger, 2010a). urban heat islands (uhi) are typical microclimatic phenomena in urban areas. the air temperature of urban areas is significantly higher at night compared to the rural areas (landsberg, 1981). the phenomenon has a horizontal as well as a vertical character. according to the typical uhi thermal profile a steep temperature gradient occurs at the rural/urban boundaries (cliff), and thereafter the temperature increases along steady horizontal gradient (plateau) and the highest temperature is at the urban centre (peak). vertically the positive temperature anomaly can be detected reach up to 200-300 meters (unger, 2010a). in general, a 0.5-1°c positive anomaly can be identified in urban areas compared to rural areas depending on the density and extent of built-up areas. local urban climate is a phenomenon formed by several complex processes (probáld, 1974). several publications appeared that use aerial and satellite remote sensing data to study the changing urban environment due to the dynamically increasing population. considering the current study a significant advancement was the assessment of roth et al. (1989), who used infrared (nir) band of noaa avhrr satellite to monitor surface temperature. according to their experiences the pattern of heat release had a stronger correlation with the land cover during the day compared to the night. it is contradictory to the results calculated from measured air tem24 gémes et al. (2016) perature values at 2-3m height above the surface. nichol (2005) compared aster night-time thermal infrared data with landsat 7 (etm+) daytime data to study the relationship between surface temperature and urban morphology during a daily temperature cycle. the research found the meso scale processes more important in the ubl at night, while during the day they were significant rather in the ucl. purnhauser (2001) investigated the urban climate of szeged in different seasons and used the sky view factor (svf) defined by oke (1988). it was found that in open, green areas the longwave radiation is significant; in narrow streets with high buildings an ‘urban canyon effect’ was observed, because the longwave radiation was trapped decreasing the loss of radiation to the atmosphere. soósné (2009) assessed the urban climate of hungarian and central european cities using surface temperature, land cover and vegetation indices data from the modis sensor, and aster surface temperature data. she evaluated the spatial pattern of uhi in all 4 seasons and in 4 periods during a day (dawn – morning – afternoon – evening). gábor and jombach (2009) used landsat tm data to investigate the relationship betwee n 14 different land use class and the surface temperature. the spatial pattern and intensity of uhi in szeged were assessed and evaluated by unger et al. (2010b) using measured air temperature field measurements and surface temperature datasets acquired by an airborne remote sensing system. study area urban climate is highly dependent on population density. in hungary 70% of the population lives in urban areas (in 346 towns and cities in total) (ksh, 2015). szeged is the third most populous city in hungary (with 163000 inhabitants). the number of inhabitants was increasing until the 1990s, and afterwards a decreasing tendency has been observed. the reasons behind the changes are the countrywide characteristic natural decrease of the population, furthermore, the migration of the people to the neighbouring villages. a migration surplus can be observed in szeged since 2007 (ksh, 2015). the macroclimate of an area also influences the urban climate. hungary, and therefore szeged being located on the south hungarian great plain (fig. 1), belong to the temperate zone; cf type of köppen’s climate zones (warm continental climate and with significant precipitation in all seasons). péczely (1979) categorised szeged into the warm-dry climate zone based on its water and heat balance. the annual mean temperature, the mean summer temperature and the mean annual precipitation are 10.6°c, 20,3°c, and 489mm, respectively. the average total hours of sunshine at szeged is 250-280 in summer months and 50-80 in winter months (omsz, 2016). the city structure is characterised by avenues and boulevards built during the reconstructions after the great flood in 1879. the river tisza devides the city in two parts: southeast from the river, the area is mostly characterised by larger urban green areas and, family fig. 1 study area (1 alsóváros, 2 baktó, 3 béke-telep, 4 belváros, 5 felsovaros,6 iparváros,7 kecskes, 8 kiskundorozsma, 9 klebensbergtelep, 10 makkosháza-fodorkert, 11 móraváros, 12 odessza, 13 petőfi-telep, 14 rókus, 15 szentmihály, 16 szőreg, 17 tápé, 18 újrókus, 19 újszeged) satellite based analysis of surface urban heat island intensity 25 houses with gardens. north of the river the city centre, housing estates and industrial areas can also be found (fig. 1). for the uniform description of the local climate features a local climate zone (lcz) classification was developed. the categories can be well applied on plains, where the influence of the relief on the climate is less strong than in areas with large height differences (stewart and oke, 2012). the categories were defined based on the land cover, resulting in 10 urban and 6 rural categories. the first 3 urban categories are characterised by mainly built-up areas, green areas are represented only by a few trees. in the case of the following 3 categories the ratio of green cover is increasing, and the rest of the categories have open green areas and low builtupdensity. lelovics et al. (2014) mapped the local climate zones in szeged (fig. 1) using a building database, aerial photos, topographical maps, rapideye satellite images, an infrastructure database, svf values, building height and roughness data, albedo values of the different surfaces, ndvi images and clc land cover data. the following categories were identified in their work in the city of szeged: (2) compact mid-rise, (3) compact lowrise, (5) open mid-rise, (6) open low-rise, (8) large lowrise and (9) sparsely built. data and methods landsat 4, 5 tm, landsat 7 etm+, and landsat 8 oli/tirs data from the period between 1984 and 2016 were applied in this research (table 1). for the long-term assessment, images from the same period in july, with a 10 year interval were evaluated describing summer conditions. i interannual changes were assessed using one image for each seasons between 2015 and 2016. the raw (dn) pixel values were processed using the semi automatic classification plugin (scp) of the open source qgis software (scp) along two parallel workflows (fig. 2). on one hand the data of the thermal band was processed, on the other hand a supervised classification was carried out on the the visible and infrared bands. emissivity values assigned to each class were applied during the land surface temperature (lst) calculations. the data sets used for the analyses needed to be preprocessed to land surface temperature. each data set was preprocessed using a data specific workflow that does not use any ancillary data. during the first step, the raw digital numbers (dn) of the tm, etm+ and oli sensors were converted to at-satellite or top-ofatmosphere (toa) spectral radiances (lλ in wm -2sr-1m1) using: lλ = ml*qcal + al (1) where ml and al are respectively the band-specific multiplicative rescaling factor and the additive rescaling factor, which are both available from the metadata. qcal is the quantized and calibrated standard product pixel values (dn). in the next step, the toa radiances of the visible to swir bands were converted to unitless toa reflectances ρp by: ρp= π∗lλ∗d2 *(esunλ∗cos(θs))-1 (2) where d is the earth-sun distance in astronomical units at the acquisition time, esunλ is the band specific mean solar exo-atmospheric irradiances, and θs is the solar zenith angle in degrees, which is equal to θs = 90° θe where θe is the sun elevation as given in the metadata. to derive the surface reflectance, it was required to apply some sort of atmospheric correction. in this research, no detailed data was available about the state of the atmosphere at the time of the data acquisition, therefore the dark object subtraction (dos) method (moran et al., 1992) was applied to the data sets assuming that within an image some pixels are in complete shadow and their radiances received at the satellite are due to atmospheric scattering (chavez, 1996). the surface reflectance is then: ρs =[π∗(lλ−lp)∗d2] *(esunλ∗cos(θs))-1 (3) where lp is the path radiance (sobrino et al., 2004): lp=ml∗dnmin+al−0.01∗esunλ∗cos(θs) *(π∗d2)-1 (4) the surface reflectance values were used to classify the data with the spectral angle mapping algorithm (kruse et al., 1993) into 4 land cover classes (water, vegetation, bare soil, built up) and to calculate ndvi values. the thermal bands were converted to at-satellite brightness temperature by: table 1 satellite images (a: long-term / b: seasonal assessment) and meteorological data (omsz, ogimet) used in the assessment sensor acquisition date/time pixel size (vnir/tir) [m] daily mean temperature [°c] daily maximum temperature [°c] vis (km) landsat 4 tm 31-jul-1984 a 30/120 22.8 30.3 n.a. landsat 5 tm 27-jul-1994 a 25.0 34.0 n.a. landsat 7 etm+ 22-jul-2004 a 30/60 26.4 34.6 28 landsat 8 oli/tirs 18-may-2015 b 30/100 16.9 24.1 50 21-jul-2015 a,b 25.3 32.4 70 23-sep-2015 b 17.5 23.1 15 22-feb-2016 b 7.0 10.7 50 26 gémes et al. (2016)                    11ln 1 2  l k kt b (5) not possible to apply the split window algorithm on landsat 8 data (usgs landsat 8, 2016), empirical emissivity values e (weng et al., 2004; mallick et al., 2012) for the earlier derived land cover classes were used with the following formula to convert the brightness temperatures to surface temperature: tsλ = bt / [ 1 + (λ * bt / p) ln(e) ] (6) where λ is the wavelength of emitted radiance, and p = h * c / s (1.438 * 10^-2 m k) (7) with h is planck’s constant, s is boltzmann constant, and c is the velocity of light. the surface urban heat island (suhi) intensity can be defined as the difference between the temperature of urban and rural areas at ground level. szeged meteorological station and its 750 m wide buffer zone was used as reference region in this study. this area was also used as reference for previous air temperature measurements of an urban climate research by unger (2010a). it accurately represents the main land cover types around the city (arable land, meadow-pasture, and forest). the spatial pattern of the suhi intensity was analysed for the whole city and along a profile. the initial point of this line was the centre point of the reference area, the szeged meteorological station (fig. 1). during the allocation of the profile it was important to cross iparváros (an industrial area), areas of different built-up ratio and vegetation cover in this research the following main questions were addressed: 1) how the pattern of lst changed during the investigated 30 years in szeged? what is the relationship between the ratio of built-up areas/vegetation cover and the calculated lst values? 2) how the intensity of surface urban heat island (suhi) changed compared to the reference rural zone in the investigated period? 3) what is the interannual pattern of lst in the predefined local climate zones? 4) what are the characteristic seasonal features of the spatial pattern of suhi? fig. 2 workflow of lst calculation in qgis using semi automatic classification plugin satellite based analysis of surface urban heat island intensity 27 results daytime surface temperature images with 30 m spatial resolution were prepared for nearly the same summer day in 1984, 1994, 2004 and 2015, and for one day in each season at same time intervals between spring 2015 and winter 2016 for the city of szeged. for the same dates ndvi values were calculated in 30 m spatial resolution using the red and infrared bands in the data sets. during image selection important criteria were the lack of cloud cover, since it reflects characteristic weather conditions in the given seasons and the absence of precipitation. the appropriate conditions were checked and confirmed by meteorological datasets (table 1). lst and ndvi between 1984 and 2015 in the investigated urban districts the most significant changes of built up areas were observed between 1984 and 2004 (fig. 3). in the investigated 30-years-long period the highest difference between the mean lst values was observed in the case of petőfi-telep exceeding even 7°c. lst decrease was observed in none of the investigated districts (table 2). table 2 changes of lst and ndvi in city districts in the investigated 30 years district δ lst δ ndvi 1 alsóváros 5.76 0.09 2 baktó 5.27 0.12 3 béke-telep 6.30 0.06 4 belváros 5.48 0.15 5 felsovaros 5.33 0.19 6 iparváros 6.55 0.04 7 kecskes 4.78 0.09 8 kiskundorozsma 5.69 0.06 9 klebensbergtelep 6.20 0.08 10 makkosháza-fodorkert 5.84 0.17 11 móraváros 5.83 0.09 12 odessza 3.30 0.21 13 petőfi-telep 7.08 0.04 14 rókus 6.11 0.10 15 szentmihály 5.38 0.06 16 szőreg 6.10 0.03 17 tápé 6.51 0.03 18 újrókus 6.44 0.10 19 újszeged 6.24 0.06 fig. 3 changes of lst between 1984 and 2015 28 gémes et al. (2016) the observed slight changes in ndvi values were in concordance with the significant increase of the temperature (e.g. in the case of szőreg, petőfitelep, iparváros). in those districts where a larger increase in vegetation cover occurred, only lower lst values were detected (e.g. odessza). the most spectacular changes happened at such areas where vegetation was replaced by built-up areas (e.g. shopping malls, industrial areas). a relatively strong correlation (r=-0.69) between the vegetation indices and the changes in the surface temperature values can be identified. however, vegetation seems to be a major determining factor of lst changes, the surface material (albedo) and its geometry, furthermore the actual weather conditions also significantly impact the lst changes. spatial pattern of daily suhi intensity based on lst values, the phenomenon of surface urban heat island was the most observable at midday and early afternoon, however urban heat islands based on the measured air temperature differences are the most pronounced at night. the applied landsat images were captured between 9.30 and 10.30, thus they were not expected to show the highest differences (namely the maximum of suhi intensity) compared to the rural areas. apart from this, the temperature of the built-up urban areas significantly exceeded the mean temperature of the rural areas (fig. 4). the highest positive intensity was observed at the industrial areas in all cases, and the rate exceeded 10°c even in this morning period. the minimum values fig. 4 uhi intensity compared to the rural areas fig. 5 seasonal patterns of lst (2 compact midrise, 3 compact low-rise, 5 open midrise, 6 open low-rise, 8 large low-rise, 9 sparsely built) satellite based analysis of surface urban heat island intensity 29 were detected in the case of larger urban green areas (e.g. parks, floodplain) and the water surface of the river tisza. the highest mean positive suhi intensity was detected in the densely populated city centre and rókus districts on two out of the 4 investigated dates. the smallest mean difference was identified in a district of the outskirt area, in baktó and once in the suburban újszeged district. the least variation in temperatures was found in the city centre, while the industrial areas showed the highest standard deviation. the average difference between the surface temperature in urban and rural areas was + 1.5°c in 2015. seasonal changes of urban lst in the local climate zones according to the seasonal comparison (fig. 5) the lowest lst values were detected in the sparsely built lcz category in spring, summer and autumn (table 3), where the land cover has characteristically a lower ratio of built-up areas, but more gardens and sporadic tree cover. in winter the lowest lst values were detected in the open low-rise lcz category, which consists of mostly open areas characterized by low buildings. the differences in minimum values in winter are due to the smaller influence of vegetation. the maximum temperature values occurred in the large low-rise category in all seasons, which are mostly built up areas without vegetation. these are typically the territories of large shopping malls and their parking lots. a significant negative correlation (-0.68<r<-0.87) between the ndvi and lst values in the vegetation period was observed in the investigated districts. the lowest correlation was detected in the city centre, due to the lower vegetation cover (table 4). daytime suhi intensity along a profile in the city the profile represents the influence of the different land cover types on surface temperature. the line intersects the river tisza at two locations and has a 2800 m long suburban section as well. this section shows significant deviations in the different seasons (fig. 6). the reason for this is the seasonal change of vegetation on arable lands. after the line reaches the border of the urban zone (at 2850 m), there is a significant change of the forest cover in all seasons. this decrease is followed by the increase of lst due to the industrial area. apart from the seasonality, the absolute maximum was observed at this district (after 4000 m). the following built-up areas show a mostly steady temperature (with some exceptions). besides the sections crossing the rivers, the absolute minimum val ues were characteristic for the liget (the biggest park in új-szeged district) in all seasons except for winter. the winter curve was much more balanced, and the minimum was detected in the case of the forest area near the border of the urban area. the temperature of the water surfaces (at 7000 and 9000 m) was extremely low in all cases. table 3 statistical parameters of seasonal lst in the different local climate zones lcz lcz name min max mean min max mean min max mean min max mean 2 compact midrise 28.8 35.8 33.8 32.8 39.7 38.1 22.6 28.2 27.0 11.2 18.9 16.9 3 compact low-rise 28.6 35.4 33.0 33.2 39.5 37.5 23.3 28.3 26.9 13.2 18.9 17.1 5 open midrise 22.1 38.1 30.2 28.6 42.1 36.3 20.8 30.5 25.7 8.0 21.0 16.3 6 open lowrise 23.7 41.0 31.0 28.6 43.6 36.4 21.1 31.4 26.0 9.8 24.3 16.3 8 large lowrise 22.7 44.0 32.4 28.3 47.2 38.2 20.7 34.8 27.0 9.2 28.2 16.8 9 sparsely built 21.6 41.6 27.5 26.9 44.7 34.7 20.4 32.3 24.6 8.6 25.4 15.4 total area 21.9 34.5 27.7 26.3 37.5 32.4 19.3 27.4 23.3 10.0 22.8 16.5 18-may-2015 21-jul-2015 23-sep-2015 22-feb-2016 table 4 extremities in the relationship between average seasonal lst and ndvi values for district district r lstmean ndvimean r lstmean ndvimean r lstmean ndvimean belváros -0.56 32.58 0.42 -0.59 37.14 0.40 -0.53 26.72 0.39 móraváros -0.88 29.18 0.60 -0.83 35.09 0.55 -0.81 25.44 0.56 18-may-2015 21-jul-2015 21-sep-2015 30 gémes et al. (2016) fig. 6 temporal patterns of lst (the dashed line represents the mean temperature of the rural areas) the evaluation of the cross-section confirms how important the vegetation cover is in urban areas influencing the urban surface temperature. vegetated surface can decrease the lst even by 13°c contributing to better health conditions and a positive human comfort. conclusion the study investigated the differences of urban surface temperature compared to rural areas. the results confirmed to what rate green areas can decrease lst which has indirect impact on the air temperature. the high density of built-up areas and the huge paved surfaces are characterized by intensive warming up. in the investigated 30-years-long period the lst pattern changed only due to the new built-up areas and other urban developments. however, the absolute numbers are highly dependent on the actual weather conditions. compared to the rural areas the suhi intensity has significantly decreased, which is due to the increasing extent of built-up areas. the seasonal assessment confirmed the inverse correlation between vegetation and lst. remote sensing and gis assessments proved to be useful tools for mapping spatial and temporal patterns of urban surface temperature. the results can be used for city planning and management in environmental and physiological aspects as well to manage the phenomenon of uhi. the advantage of the applied gis method is the automation of the data processing, as a result of which homogenous data can be generated for large areas. the basic datasets can be downloaded for free and the temporal extent is more than 30 years. the disadvantage is the low temporal resolution, preventing the investigating of changes within one day. references chavez, p.s. 1996. image-based atmospheric corrections. revisited and improved photogrammetric engineering and remote sensing 62, 1025–1036. gábor p., jombach s. 2009. the relation between biological activity and the land surface temerature in budapest. applied ecology and environmental research 7, 241–251. doi: 10.15666/aeer/0703_241251 kruse, f. a., lefkoff, a.b., boardman, j.b., heidebrecht, k.b., shapiro, a.t., barloon, p.j., goetz, a.f.h. 1993. the spectral image processing system (sips) interactive visualization and analysis of imaging spectrometer data. remote sensing of environment 44, 145–163. doi: 10.1016/0034-4257(93)90013-n ksh 2015. magyarország településhálózata 2. városok-falvak.(the hungarian settlement system 2 – cities and villages) central statistical office, budapest, 88 p. 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(in hungarian) probáld f. 1974. budapest városklímája (urban climate of budapest). akadémiai kiadó. budapest, 126 p. (in hungarian) purnhauser p. 2001. a városi hőszigetet és a városi szerkezet összefüggéseinek feltárása terepi és térinformatikai módszerekkel szegeden. (assessment of the relationship between urban heat island and city structure using field data and remote sensing). university of szeged, department of climatology and landscape ecology, szeged, 65 p. 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(in hungarian) stewart, i.d., oke, t.r. 2012. local climate zones for urban temperature studies. bulletin of the american meteorological society 93 (12), 1879–1900. doi: 10.1175/bams-d-11-00019.1 unger j. 1996. városklimatológia – szeged városklímája (urban climatology – urban climate in szeged). acta climatologica et chorologica univ szegediensis 31b (urban climate special issue), 69 p. (in hungarian) unger, j. 2010a. a városi hősziget-jelenség néhány aspektusa (some aspects of urban heat island phenomenon). doctoral thesis, hungarian academy of sciences, szeged, 107 p. unger j., gál t., rakonczai j., mucsi l., szatmári j., tobak z., van leeuwen b., fiala k. 2010b. modeling of the urban heat island pattern based on the relationship between surface and air temperatures. időjárás / quarterly journal of the hungarian meteorological service 114, 287–302. usgs landsat 8, https://landsat.usgs.gov/landsat8_using_product.php [05.20.2016] weng, q., lu, d., schubring, j. 2004. estimation of land surface temperature–vegetation abundance relationship for urban heat island studies. remote sensing of environment 89, 467–483. doi: 10.1016/j.rse.2003.11.005 world bank 2014. http://datacatalog.worldbank.org/ http://www.ogimet.com/gsynres.phtml.en http://met.hu/eghajlat/ http://datacatalog.worldbank.org/ journal of environmental geography journal of environmental geography 7 (3–4), 43–51. doi: 10.2478/jengeo-2014-0011 issn: 2060-467x drought severity and its effect on agricultural production in the hungarian-serbian cross-border area károly fiala 1* , viktória blanka 2 , zsuzsanna ladányi 2 , péter szilassi 2 , balázs benyhe 1 , dragan dolinaj 3 , imre pálfai 1 1 lower-tisza water directorate, stefánia 4, h-6720 szeged, hungary 2 department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary 3 climatology and hydrology research centre, faculty of science, university of novi sad, dositeja obradovića 3, 21000 novi sad, serbia *corresponding author, e-mail: fialak@ativizig.hu research article, received 20 july 2014, accepted 15 october 2014 abstract several environmental and economic consequences of drought and the accompanying water shortage were observed in the plain area of the carpathian basin in the last decades. this area is mostly used for agriculture, thus it is a key problem in the future to maintain food safety in the changing circumstances . therefore, involvement and identification of areas affected by drought hazard and revealing steps of efficient adaptation are of high importance. in this study influence of drought severity on agricultural production is investigated in the hungarian -serbian cross-border area. the tendency in drought severity was analysed by padi and mai drought indices. the effect of drought on agricultural production is evaluat ed on maize yield data as the most drought sensitive crop in the region. increasing drought frequency and severity was indicated for the study area for the period of 1961-2012. the spatial assessment of annual padi maps revealed the higher exposure of the north and northeastern part of the study area to drought, where drought frequency was also experienced to be the highest. increased sensitivity was detected based on maize yield loss after the early 1990s and annual yields were in strong connection with d rought severity. in spite of the technological development of agriculture, environmental factors still substantially affect crop yie lds. the observed unfavourable changes in the region mean that water management and spatial planning faces conceptual cha llenges to prevent and mitigate the damages of drought. keywords: climate change, drought, padi, agriculture, yield loss introduction drought is one of the most important environmental hazards in southern and eastern europe. the lack of water during drought periods have effect on many sectors (e.g. agriculture, energy production, industrial water use, health care, tourism) (warrick et al., 1975; maracchi, 2000; svoboda et al., 2002; zeng, 2003; lei et al., 2011; ye et al., 2012; lin et al., 2013 wisner et al., 2004) and also on ecology (poiani et al., 1995, winter, 2000, parmesan, 2003, normand et al., 2007, beierkuhnlein et al., 2011, pitchford et al., 2012). drought is a complex phenomenon influenced by the quantity and temporal distribution of precipitation, temperature, air humidity etc. in hungary, due to climate change a 0.8°c rise in surface temperatures and a 60–80 mm decrease in precipitation were detected in the carpathian basin in the last century (rakonczai, 2011) and increasing rate and occurrence of drought was described in the last decades (bihari, 2006; bartholy et al., 2007). spasov et al. (2002) also reported that drought is also a quite often natural hazard in serbia; dry years were particularly frequent in the last two decades of the 20th century. the strength of drought in south-eastern europe shows different spatial distribution year by year. the map constructed from the 10% probability of pálfai drought index (padi) occurrence showing the spatial pattern of drought inside the south-eastern europe (see) region (pálfai and herceg, 2011) clearly confirms the fact that the hungarian-serbian cross-border area is seriously affected by drought. in the last decades several environmental and economic consequences of drought and the accomp anying water shortage were observed in the plain area of the carpathian basin. environmental consequences of drought are the decreasing groundwater table (m ajor and neppel, 1988; szalai, 2011; rakonczai et al., 2012), reduction surface water cover (kovács, 2008), alteration of soil properties (ladányi et al. 2009; puskás et al., 2012) and vegetation changes (biró et al., 2008; molnár et al,. 2008; ladányi et al., 2010). the great plain is highly important in agricultural aspects for its countries, since it is mostly covered by high fertility soils and the fields are used as arable lands. droughts stress due to water scarcity and heat 44 fiala et al. (2014) waves cause significant yield loss. in drought years, 40-50% loss is observed in the southern great plain, and in plot scale, total crop loss is experienced. in spite of the dramatic technological develo pment of agriculture (e.g. irrigation systems, new seeds for sowing, genetic modification), environmental factors such as climate, ecology and soil attributes still substantially affect crop yields. it is a key pro blem in the future to maintain food safety in the chan ging circumstances, therefore involvement and identif ication of areas affected by drought hazard and revealing steps of efficient adaptation are of vital i mportance. in this study the influence of drought sever ity on agricultural production is investigated in the hungarian-serbian cross-border area of the see region. drought severity is calculated by two indices mostly used in hungary and serbia, and its effect on agricultural production is evaluated. study area the study area, south hungary and the plain areas of vojvodina, is situated in the southern part of the carpathian basin (fig. 1). similar physical-geographical features describe the area, where annual mean temperature is around 11 °c and the annual amount of precipitation is between 500-600 mm. in july the mean temperature is around 21 °c and 23 °c, the precipitation in the summer half-year is at about 300 mm (smailagic et al., 2013; omsz, 2014). the dominant soil type is chernozem and its subtypes both in the hungarian and the serbian areas; furthermore meadow and sandy soils can also be found. the dominant land use type in the area is arable land based on corine land cover 2006, thus the effect of drought on the agricultural production has high importance on the economy of the region. methods calculation of drought severity meteorological factors play a significant role in the formation of drought, thus by their assessment, drought severity can be quantified. pálfai drought index (padi) (pálfai and herceg, 2011) and the moisture availability index (mai) (hargreaves, 1975) were used to describe droughts of the past decade for the right bank-side catchment of tisza and in vojvodina. the padi uses monthly temperature and precipitation data for the calculation and it characterises the drought with one numerical value that is associated with one agricultural year. the index is calculated as follows:   gwptsept octi ii aug apri i kkk wp t padi ***100* 5 *           where ti is the mean monthly temperature from april to august, pi is the monthly sum of precipitation from october to august, wi is a weighting factor expressing fig. 1 location of the study area and the meteorological stations drought severity and its effect on agricultural production … 45 the importance of the months in the evolution of drought, while kt, kp, and kgw are correction factors assessing the temperature, precipitation and groundwater conditions in the preceding years. padi was calculated for each year in the period of 1961-2012. the tendency in drought severity was analysed by dividing the full period into two parts (1961-1987 and 1988-2012) calculating the average index value for both period. the changes of drought frequency were analysed by yearly drought index based on the average value of all stations. spatial analysis of drought severity was also carried out by producing drought maps for each year. the moisture availability index (mai) is a relative measure of the adequacy of precipitation in supplying moisture requirements (hargreaves 1975). the mai is suitable to evaluate the climate resource for agricultural production. the index is the ratio between monthly precipitation and reference evapotranspiration and this takes into account water requirements too (hargreaves and keller 2005). the mai can be calculated at different time scales (monthly, seasonal, and annual). the mai is calculated as: pe ae mai  where ae is the actual evapotranspiration and peis the potential evapotranspiration. analysis of the effects on agricultural production for analysing the effect of drought on agricultural production maize yield data were evaluated as the most drought sensitive crop in the region. to assess the spatial differences in yield loss, county level yield data were used for hungary in the year 2012, which was the most recent serious drought in the region. the rate of yield loss compared to the mean value of the 2000-2012 was calculated in percentage for each hungarian county. in the study area the yearly anomalies of maize yield between 2000 and 2009 were calculated and compared to the mean value of the 2000-2012 for the south-eastern hungarian counties (bács-kiskun and csongrád) and for vojvodina to assess the effect of drought in the different years and to identify the years when yield loss was significant. moreover by the analysis of the data of the two countries, it can also be identified, whether the variability of yield is similar in both countries, meaning that the changes are irrespective of the different cultivation practices. finally the yearly yield data were compared to the yearly padi values between 1961 and 2012 to reveal the connection between the drought severity and maize yields. results analysis of past and present droughts analysis of pálfai drought index in the study area based on the calculated pálfai drought indices (padi) drought severity show increasing tendency in the region. a significant increase of the average padi value was observed between the two analysed period (1961-1987 and 1988-2012) on nearly all stations (fig. 2). in the first period the average padi values varied between 4 and 5.5 °c/100 mm. the highest average value was observed on northern part of the area (örkény station), while the lowest average value was detected on the southern part (bečej station). in the second period padi values varied between 4.6 and 7.1 ° c/100 mm. in this period the drought severity was higher in the eastern part of the area, the highest average value occurred on north-eastern part (tiszakécske) also in this period. the highest increase between the periods was identified and tiszakécske station (north-eastern part), where padi value increased by 2 °c/100 mm, while a slight decrease in drought severity was observed at one station (paks on the western part). fig. 2 changes of padi mean values in the studied stations in hungary in the two partial periods 46 fiala et al. (2014) drought severity can be defined by the degree of water scarcity, though sometimes this parameter is not considered appropriate for the affected sectors. agriculture, ecology, industry and society have completely different water needs. because of these various needs this question can be approached with reference to the average precipitation of the affected area. precipitation amounts compared to the long-term average are suitable to describe the water shortage. several researchers dealt with this issue (e.g. szalai, 2009; bartholy and pongrácz, 2005) and maps of the areas with water deficiency were produced. according to these studies, water deficiency is between 100 mm and 200 mm in drought periods on the catchment area, which could be even higher in extreme circumstances. the problem can be increased when drought occurs on the same area for consecutive years since water shortage becomes more and more pronounced if no significant water refill is taken place. besides drought severity, frequency also has to be assessed to assess the importance of drought problem in the area. for assessing drought frequency regional averages were calculated for each years based on data of all stations. fig. 3 shows that not only severity, but frequency also increased. in the first period (1961-1987), the annual drought index had reached the value of 6 °c/100 mm only in 5 years (moderate drought) in the 27year long period. the most severe drought occurred in 1983, when the padi value was 6.6, which also means only moderate drought. a more considerable change could be observed in the second period (1988-2012). drought years occurred more frequently, the annual drought index exceeded the value of 6 °c/100 mm in 12 years in the 25-year long period. moreover in this period more serious droughts occurred than in the first period. heavy droughts also evolved in the region, padi va lue exceeded the value of 8 °c/100 mm in 3 years. the most severe drought occurred in 2003, when the padi value was 9.5 °c/100 mm. data have pointed out that the area is affected at least by moderate drought in every 2 years, and heavy droughts are also recorded, causing serious damages. beside the increasing severity, the variability of droughts between the years was also higher in the second period. the lowest padi value of the whole studied period (1961-2012) occurred in the second period. in the studied region, considerable spatial differences can also be observed. drought sensitivity is quite different, thus areas can be allocated where drought years occurred more frequently. drought occur most frequently on the northern, north-eastern part of the study area, thus this area is the most effected. the average drought severity, calculated for the two periods, also indicated this area as the most affected. obviously, consecutive years differ from each other; therefore the spatial pattern of drought severity is different from year to year. some characteristic example of the spatial differences is shown on fig. 4. in 1983, fig. 3 mean padi values at the studied stations between 1961 and 2012 fig. 4 distribution of padi values in 1983, 1993, 2000 and in 2007 (4-6: slight drought; 6-8:moderate drought; 8-10: heavy drought; 10-12: serous drought; 12-14: very serious drought; >14: extreme drought) drought severity and its effect on agricultural production … 47 which was the most severe drought year in the period of 1961-1987, the north-eastern part of the area was more affected. this drought was evolved due to the warmer weather from winter to august and this warm period was associated with precipitation lower than average in almost every months. the dry autumn and snowless winter of the year 1989 contributed to the formation of droughts for the next years. in 1990 the low level of groundwater, followed by a hot july and august with no rainfall, resulted in huge losses in maize yield. the same causes could be determined the development of drought in 1992 and 1993 with similar severity to that of 1990. based on the temperature data for 1992, the annual mean temperature for the april-august period was 18.8°c, which was not extreme, however the mean monthly temperature in august exceeded 25 °c, which meant new records since observations. the number of heat days in the three summer months was over 37 days, which is twice as much as the average value. the last quarter of the previous year precipitation exceeded the long-term average. after december, the monthly sums were below the long-term average, except june. during the warmest period there was no precipitation, the dry period without precipitation was more than 30 days on the affected area. the padi values were between 11-14 °c/100 mm. the drought in 2000 was preceded by huge inland excess water inundations as a result of the precipitation in november and december in 1999, which was twice the amount of the average precipitation of these months. january and february was characterised by few precipitation, and then march and april were slightly more humid. however, after 7th april, an extremely long dry period started lasting until the first week of july then it went on after a short break. 216 mm precipitation was recorded for the whole calendar year in szeged. most stations in the danube-tisza interfluve measured less than 300 mm. the precipitation did not reach 60 mm from april to august. the number of heat days was extremely high. these both contributed to severe drought, padi values exceeded 10 °c/100 mm (fig. 4). the drought affected the area of vojvodina much more seriously, here the padi values reached 12-14 °c/100 mm. prior to the drought in 2007, the area was affected largely by inland excess water inundations and a recordsize flood in 2006. in spring time of 2007 water scarcity could be expected since a long arid period was experienced in the autumn and winter of 2006. the 3-month precipitation sum was only half of the long-term average. besides these, winter months were unusually warm. the monthly mean temperature was around 4–5°c, while the long-term average is -1-1.5°c. accordingly, evaporation was higher, which further increased the water shortage. an average amount of precipitation fallen at the beginning of spring, and then in april hardly any rain could be measured. the situation slightly moderated during the period starting in may defined by heavy rains, however, serious drought evolved as the summer heat arrived. the daily maximum temperature from mid-july exceeded 36°c. there were 50-60 heat days on the great hungarian plain. the precipitation was half of the longterm average. precipitation further decreased in august – one third of the amount typical for the area fell, which resulted in extreme drought (fig 4). in 2007 moderate and mild drought could be observed in vojvodina according to the values of pálfai index. the most severe drought of the past 50 years evolved in 2012. considering the national average, scarcely more than 400 mm precipitation was measured in 2011, which is two-thirds of the long term average. the annual precipitation was 325-400 mm in the study area (fig. 4). the dry period continued in the first half of 2012. the precipitation on the catchment area was 30% less, while at certain places there was a decrease of 50% compared to the long-term average. on average, 225 mm precipitation was recorded until august (only about 5 mm fell in august), while the long-term average was 380 mm. the entire catchment area, especially the ne part of the area, was extremely dry (fig. 4). the extremely high temperature in july and august intensified the unusual aridity. the monthly mean temperature was 3-4°c over the long-term average and there were 60 heat days in this year. due to the superponation of the extreme weather elements, extreme and severe droughts developed on 80% of the catchment area. further analysis of drought indices in the vojvodina part of the study area dry years were particularly frequent in the last two decades of the 20 th century in serbia as well (spasov et al., 2002; gocic and trajkovic, 2013). gocic and trajkovic (2014) allocated north serbia as a region with precipitation values under the average value of serbia. the demonstration of the results was based on the meteorological station rimski sancevi, which is located 15 km from novi sad, because its statistics are exceedingly similar to the average meteorological values throughout vojvodina. measuring precipitation throughout critical months such as july and august for the period of 88 years (1924-2012) shows that 84.27% of the years july, and 84.27% of the years august were arid. the amount of the precipitation evidently was not sufficient to satisfy crop water requirements, which was above 100 mm from june to august (table 1). the moisture availability index (mai) in the region very low, particularly in august (table 2), and there are some spatial differences (table 3). regions where mai index is under 0,33 are very deficient, 0,34-0,66 moderately deficient, 0,67-0,99 somewhat deficient, 1,01,33 adequate moisture and above 1,34 excessive moisture. according to analysis the climate circumstances in vojvodina are semi arid, and semi humid. the period 1924-2003 was analysed in terms of sufficient amount of water, specified by the prec ipitation that crops need for regular growth consistent with hardgrave’s’ model and index. model is based on the analysis of 75% precipitation (p) and potential evapotranspiration (eto). based on the assessment, the area of vojvodina has semi arid or arid climate during summer, which is not favourable for succes sful crop production, thus irrigation has high i mportance in the region. 48 fiala et al. (2014) table 1 percentage of the arid periods for all precipitation amounts in july and august, in vojvodina (hms novi sad), from 1924 to 2012 precipitation (mm) july august drought severity nr of years % nr of years % 0-25 13 14.6 21 23.6 extremely drought 26-50 33 37.1 24 27.0 very drought 51-75 19 21.4 19 21.3 drought 75-100 10 11.2 11 12.4 moderately drought 75 84.3 75 84.3 total drought 101-125 7 7.9 10 11.2 moderately rainy >126 7 7.9 4 4.5 pluvial total 89 100 89 100 table 2 moisture availability index (mai) in vojvodina parameter months v vi vii viii ix p (mm) etp (mm) mai 46 77 0.60 68 118 0.58 50 139 0.36 40 130 0.31 32 61 0.52 table 3 potential evapotranspiration (eto), and precipitation with probability of 75% and moisture availability index (mai) months vi vii viii vi-viii eto 100 100-120 100-120 300-340 p (mm) subotica 52 44 44 140 novi sad 70 44 39 165 sremska mitrovica 70 44 32 174 mai subotica 0.52 0.44-0.37 0.44-0.37 0.46-0.41 novi sad 0.70 0.44-0.37 0.39-0.32 0.55-0.48 sremska mitrovica 0.70 0.44-0.37 0.32-0.26 0.58-0.51 analysis of the effects on agricultural production yield loss according to the wheat and maize yield data of hu ngarian central statistical office, the most dominant field crops, in the period of 2000-2012 yields in 2000, 2002, 2003, 2007, 2009 and 2012 were below the average of the period, and maize showed the greater anomalies. the highest decrease of crop yield wa s seen due to the drought in 2012 (fig. 5). in this year, the study area was highly affected, the maize yield was decreased by over 50% in csongrád county, while in bács-kiskun county the crop yield dropped by 44% as compared to the average. the crop yield map for 2012 (fig. 5) shows that the southern counties experienced the most substantial reduction. how fig. 5 impact of drought in 2012 on the maize crop yield in the hungarian counties (with reference to the mean value for 2000-2012) drought severity and its effect on agricultural production … 49 ever, there were some hungarian counties where, in the same year, farmers could harvest maize with yield exceeding the long term average values. in vojvodina in 2012 remarkable yield loss could be observed, similarly to the southern hungarian counties. there was a 50% decrease in maize yield in 2012 compared to 2011, furthermore reduced yields for less sensitive cereals were also observed (wheat: 8%, sugarbeet: 30%, sunflower: 11% , soy: 35%, potato: 30%, beans: 40%, clover: 30%, tobacco: 25%) (mészáros et al., 2013). figure 6 illustrates the changes in maize yield, as the most drought sensitive plant in the region between 2000 and 2009. the variation of yields are similar in both countries. the most remarkable decrease occurred in 2000, 2003 and 2007, while the best crop yields were recorded for the years 2004, 2005 and 2006. the highest yield loss in vojvodina occurred in 2000, when the yield loss exedded the loss experienced in the southern hungarian counties. in the other years strongly affected by drought (2003, 2007) the hungarian part suffered bigger damage owing to the sandy soils typical for the bács-kiskun county area (due to the better water retention capacity of chernozem, meadow and alluvial soils in csongrád county and vojvodina). the greatest changes both in positive and negative directions were found in the hungarian part. analysis of the connection between drought and crop yields to reveal the connection between the drought severity and maize yields, yearly yield data were compared to the yearly padi values between 1961 and 2012. in the first analysed period (1961-1987) the yearly yield data and padi index value do not show connection. in this period serious droughts do not occurred, while the yield data show continuous development of the maize production. in the second period the yearly maize yields have higher variability. this higher variability is caused by production changes after the political system change, because the transformation of plot structure was disadvantageous for unified irrigation, thus the rate of irrigation was greatly decreased and agro-technology is also changed. the decreased irrigation and changed agro-technology caused that the area became more sensitive to environmental hazards. due to this increased sensitivity annual yields are in strong connection with drought sensitivity. discussion and conclusion based on the temporal changes of the pálfai drought indices (padi) it can be stated that drought severity considerably increased in the region. a significant increase of the average padi value was observed between fig. 6 changes of maize yield in the study area (vojvodina and south-eastern hungary) compared to the multiyear average between 2000-2009 (source: research institute of agricultural economics, hungary and banski et al. 2010) fig. 7 the pálfai drought index (padi) annual values and the annual average maize yield for 1961-2012 50 fiala et al. (2014) the two analysed period (1961-1987 and 1988-2012) in the case of nearly all stations. on some stations the rate of increase reached 30-40 %, which is mainly caused by the apparent temperature increase. moreover, in the 1988-2012 period more serious droughts occurred than in the previous period, thus heavy droughts also evolved from the 1990s. besides drought severity, frequency has also increased in the area. if the tendency continues in the future, the 30-year average value of padi is expected to be around the value of 8 until the end of the 21 st century (blanka et al. 2014). drought severity in consecutive years can be significantly different; therefore, the spatial pattern of drought severity is different from year to year. at several times no drought occurred in subsequent years on a certain location. on the other hand consecutive years with drought also occurred, especially from the 1990s. these significant changes in drought characteristics also had serious economic consequences. the damages caused by drought could be indicated by the rate of agricultural yield loss, since this reflects the impact of this phenomenon most visibly. the damages caused by drought are also influenced by the tolerance of cultivated crops, soil properties and the presence of irrigation. the most sensitive plants are maize, legumes, vegetables and cereals. on the areas of kecskemét, kiskőrös, tiszaalpár, csongrád and szeged, yield losses of some crops and the consequent economic losses were determined (table 4) to revel the effects of drought on different types of crops with different sensitivity. the data clearly shows that water shortage has an impact on all cultivated crops. the financial value of lost yield is incredibly high where the added work is greater, thus the damages of the given sector are especially severe. yield loss data in hungary demonstrated the intensifying damages as a result of the more frequent droughts from the 1990s (fig 7). because of the considerable spatial differences in drought severity in hungary, the yields losses are also distributed unevenly. based on statistical data the southern hungarian counties experienced the most substantial reduction, as it was shown also in 2012. based on the analysis of the 20002009 period the effect of droughts on crops in vojvodina is similar to the southern hungarian counties. in hungary the economic losses due to the drought in 1990 were estimated to reach 50 billion huf, for 1992 the damages arising from the drought may have been 30 billion huf (rátky, 1992; csizmadia, 1992). in 2003 the damage due to drought was estimated at 40 billion huf (láng et al., 2007). yield loss as a result of drought in 2012 reached 400 billion huf (kerpely, tripolszky, 2013). in serbia the damages resulting from yield loss reached 600 million eur in 2007 (popov and frank, 2013), and in 2012 damage at 2000 million eur was reported (mészáros et al., 2013). in hungary in the danube-tisza interfluve, considering that the groundwater level had considerably decreased, the damages caused by yield loss due water shortage reached 11 billion huf on average on the catchment of tisza river (almost 5000 km 2) . a special feature of the study area is the important tradition of vegetable and fruit cultivation that makes it sensitive to water deficit and drought. it is also important to mention that the mostly affected sectors are linked to smallholders, whose financial stability is much worse than that of large agricultural farms, where cereal production is typical. consequently, damage can be expressed in numbers but has a lot more serious long term impact on the farms. the observed unfavourable changes in the region mean that water management and spatial planning faces conceptual challenges to prevent and mitigate the damages of drought, since the changing climatic and hydrological conditions generate new and increa sing environmental and consequently social hazards in the future. planning sustainable development requires the integration of economic, social, and environmental considerations as a key to maintaining basic living standards and protecting ecosystems. to reach these aims all the possibilities of agro-technological development, changing production structure, land use changes, development of irrigation technology, new concept in water management (water retention, reuse of water resources) and dynamic approach in nature conservation should be considered. table 4 yield losses of some crops on the study area kecskemét kiskőrös tiszaalpár csongrád szeged area [ha] 123 768 97 592 49 752 18 701 106 197 gold crown value 11.4 8.5 19.7 17.7 9.1 crops yield loss (t/ha) yield loss [million huf/ha] cereals 0.3 0.3 0.3 0.3 0.3 20 maize 0.9 0.9 0.8 0.8 1.0 70 potato 2.0 2.0 2.0 2.0 2.0 240 vegetables 2.5 2.5 2.0 2.0 2.2 360 pasture 1.5 1.5 1.3 1.4 1.2 6 fruit 3.3 3.4 3.5 3.8 5000 drought severity and its effect on agricultural production … 51 acknowledgements this research was supported by the ipa cross-border cooperation programme of the european union under the project wahastrat (husrb/1203/121/130). references banski, j, bednarek-szczepańska, m. , ł. czapiewski, k., mazur, m. 2010. perspectives for agriculture of vojvodina in the light of scenarios and models elaborated in the framework of the research projects of the european union. project report prepared for centre for strategic economic studies “vojvodina-cess. warsaw, 2010. online at: https://www.igipz.pan.pl/tl_files/igipz/zgwirl/ projekty/raport_vojvodina.pdf bartholy, j., pongrácz, r. 2005. tendencies of extreme climate indices based on daily precipitation in the carpathian basin for the 20th century. időjárás 109, 1–20. bartholy, j, pongrácz, r., barcza, z., haszpra, l., gelybó, gy., kern, a., hidy, d., torma, cs., hunyady, a., kardos, p. 2007. a klímaváltozás regionális hatásai: a jelenlegi állapot és a várható tendenciák. földrajzi közlemények 131/4, 257–269. beierkuhnlein, c., thiel, d., jentsch, a., willner, e., kreyling, j. 2011. ecotypes of european grass species respond differently to warming and extreme drought. journal of ecology 99, 703–713. doi: 10.1111/j.1365-2745.2011.01809.x bihari, z., lakato,s m., mika, j., szalai, s., szentimrey ,t. 2006. hazánk éghajlatának néhány jellemzője az 1956-2005 időszakban, kitekintéssel a globális tendenciákra. in: „50 éves a légkör” légkör 51, különszám 24–28. biró, m., révész, á., molnár, zs., horváth, f., czúcz, b. 2008. regional habitat pattern of the danube-tisza interfluve in hungary ii the sand, the steppe and the riverine vegetation, degraded and regenerating habitats, regional habitat destruction. acta botanica hungarica 50/1–2, 19–60. doi: 10.1556/abot.50.2008.1-2.2 blanka ,v., ladányi, zs., mezősi, g. 2014. climate change in the 21th century. in. blanka v, ladányi zs. 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https://www.linkedin.com/redir/redirect?url=http%3a%2f%2fwww%2ewwf%2ehu%2fmedia%2ffile%2f1369810200_felelos_vallalati_vizgazdalkodas%2epdf&urlhash=_9k9&trk=prof-publication-title-link https://www.linkedin.com/redir/redirect?url=http%3a%2f%2fwww%2ewwf%2ehu%2fmedia%2ffile%2f1369810200_felelos_vallalati_vizgazdalkodas%2epdf&urlhash=_9k9&trk=prof-publication-title-link http://bookline.hu/szerzo/lang-istvan/27820 irrigation water use in the danube basin: facts, governance and approach to sustainability journal of environmental geography 12 (3–4), 1–12. doi: 10.2478/jengeo-2019-0007 issn 2060-467x irrigation water use in the danube basin: facts, governance and approach to sustainability diana dogaru1*, wolfram mauser2, dan balteanu1, tatjana krimly3, christian lippert3, mihaela sima1, jan szolgay4, silvia kohnova4, martin hanel5, mariyana nikolova6, sandor szalai7, anton frank8 1institute of geography, romanian academy, d. racovita 12, 023993 bucharest, romania 2institute of farm management, university of hohenheim, schloß-osthof-südflügel, 70593 stuttgart, germany 3department of geography, ludwig-maximilians university, luisenstrasse 37, d-80333 munich, germany 4department of land and water resources management, faculty of civil engineering, slovak university of technology, radlinského 11, block c, 12th floor, 810 05 bratislava, slovak republic 5faculty of environmental sciences, czech university of life sciences prague, kamycka 129, 165 00 prague suchdol, czech republic 6national institute of geophysics, geodesy and geography, bulgarian academy of sciences, acad. georgi bonchev str., bl. 3, 1113 sofia, bulgaria 7faculty of agriculture and environmental sciences, szent-istván-university, páter károly utca 1, h-2100 gödöllő, hungary 8leibniz supercomputing center, bavarian academy of sciences and humanities, boltzmannstraße 1, 85748 garching, germany *corresponding author, e-mail: dianadogaru77@yahoo.com research article, received 10 may 2019, accepted 25 october 2019 abstract in this paper we assess the irrigation water use in the danube basin, highlight its complexity, identify future challenges and show the relevance for a basin-wide integrative irrigation management plan as part of a more holistic and coherent resource policy. in this sense, we base our integrative regional assessments of the water-food-energy nexus on insights from an extensive review and scientific synthesis of the danube basin and region, experimental field studies on irrigation and agricultural water consumption, current irrigation related policies and strategies in most of the danube countries, and regulatory frameworks on resources at european union level. we show that a basin-wide integrative approach to water use calls for the evaluation of resource use trade-offs, resonates with the need for transdisciplinary research in addressing nexus challenges and supports integrative resource management policies within which irrigation water use represents an inherent part. in this respect, we propose a transdisciplinary research framework on sustainable irrigation water use in the danube basin. the findings were summarized into four interconnected problem areas in the danube basin, which directly or indirectly relate to irrigation strategies and resource policies: prospective water scarcity and danube water connectedness, agricultural droughts, present and future level of potential yields, and science based proactive decision-making. keywords: basin-wide irrigation management, resource policies, transdisciplinary research, danube basin introduction irrigation is by far the largest user of blue water regionally and worldwide (foley et al., 2011; fao, 2012). it represents an important technological measure in agricultural production to compensate for a shortage of rainfall during the growing season. th is shortage can be structural and physiological whenever there is permanently not enough rainfall to produce yields and it can be temporal with irrigation used episodically for drought mitigation. irrigation also represents an economic leverage point for farmers to increase yield in environments with natural water stress. these aspects and the fact that irrigation water leaves the system through the atmosphere and cannot be reused make irrigation central to sustainable water resources management. it also calls for widening the term irrigation management from the narrow technical understanding of the management of irrigation systems towards a river basin approach, which includes issues like optimized allocation of irrigation within a basin, balancing blue wat er demand and availability as well as upstream-downstream benefit sharing. considered from a systemic point of view, irrigation adds complexity to the water-food-energy nexus because irrigation converts comparatively large amounts of blue into green water, which links food production to regional blue water availability. the use of blue water also makes irrigation, and thereby food production, an upstream-downstream issue and creates the strongest spatial interdependencies of all water food-energy nexus factors. water connects different geographical regions and transfer valuable energy and water resources from upstream to downstream. as a consequence, water management cannot solely be local. in order to warrant sustainability and maximize welfare of all participants in a watershed, it should be explored ways to identify the most beneficial, efficient and equitable use of the common resource. 2 dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. furthermore, climate change directly influences irrigation regimes through changes in blue water demand and potential agricultural yields (molden et al., 2010; porter et al., 2014). regional blue water availability might also significantly change, thereby putting pressure on the regional balance in the use of a basin’s land and water resources (rosenzweig et al., 2014; iglesias and garrote, 2015). irrigation plays a central role in achieving water, food (and more broadly land) and energy related sustainable development goals (un, 2015). they are not only strongly interlinked with each other but are also strongly connected with social and economic sustainable development goals (nilsson et al., 2016). there is no doubt that each goal is meaningful by itself in achieving sustainable development. nevertheless, today the ways towards reaching them are not operationalized in terms of management and verification. the central scientific and operational challenge in achieving the sustainable development goals until 2030 is how to align the pathways towards reaching each one of them in ways that amplify each other. the above mentioned aspects are relevant particularly in the context of doubling global agricultural production until 2050, in order to satisfy the demand of a growing and wealthier world population (fao, 2012). agricultural production depends on climate and on natural resources of which, land and water are the most important. rainfall, which hits the land surface is stored in the soils and thereby makes land and water interconnected and partly interchangeable. access to more rainfall can be granted to agriculture by expanding the cropland area in non-cultivated places. rainfall can also be used more efficiently on today’s cropland through improved agricultural management practices. finally, blue water can be added to the rainfall through irrigation to improve water availability to the crops. since suitable cropland is limited and since most of it is already in use, expansion of cropland area is not considered feasible and sustainable to raise agricultural production (zabel et al., 2014). this is supported by the need to protect natural habitats and biodiversity. the most promising way to satisfy future demands is to increase input efficiency in crop production. gains in water use efficiency (i.e. reducing the amount of water that is needed to produce a kilogram of yield) both in rain-fed and irrigated agriculture, therefore, represent the main pathway towards satisfying future food demands (mueller et al., 2012; brauman et al., 2013), including overcoming environmental and economic impacts of unsustainable water use. closing the gap between current agricultural production and future demand, therefore, calls for an intensification that is sustainable (godfray and garnett, 2014; mauser et al., 2015). since the level of intensification that is still sustainable is not easy to define and since this level can vary from field to field only rough estimates exist today on the gap between current yields and a possible sustainable increase in yield. this has been summarized for different countries by bruinsma (2009) and is shown in fig. 1. fig. 1 shows the difference between the actual (in blue) and the agro-ecologically attainable yield (in red) for wheat. negative red columns mean that the actual yields are already above the ecologically attainable level, positive red columns mean that reserves exist for sustainable intensification. three countries in fig. 1 are part of the danube basin: germany, hungary and romania. whereas in germany the current yield levels fig. 1 difference between actual and agro-ecologically attainable yield for wheat in selected countries, where vs stands for ‘very suitable’ land for crop production potential (i.e. the attainable yield is 80 to 100 percent of the maximum constrained-free yield); s is ‘suitable’ land (i.e. 60-80%); ms means ‘moderately suitable’ land (i.e. 40-60%) (from bruinsma, 2009). the agro-ecological zone (aez) defines a standardized methodological framework for the characterization of climate, soil and terrain conditions relevant to agricultural production (fisher et al., 2012, 2002) dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. 3 are beyond the ecological limit, hungary and romania still hold reserves of 100% and more for sustainable intensification in rain-fed and irrigated agriculture. this makes it worthwhile to thoroughly examine the danube basin for hot-spots for land use change, intensification and increase in water use efficiency. these aspects call for exploring and developing basin-wide, coordinated and adaptable management approaches which ensure the most beneficial, sustainable and equitable use of blue and green water resources, specifically for irrigation. spatial and sectoral alignment of the water, food and (renewable) energy management is, therefore, the key for adaptive, sustainable and integrated irrigation schemes, which create both downstream and upstream welfare effects. how does this translate to river basins within large political entities like the european union? the eu constituted on the subsidiarity principle and the idea of solving each problem at the institutional scale at which it can be solved in the most appropriate and effective way. how does the idea of managing irrigation in the nexus sense relate to the subsidiarity principle in a situation when the administrative boundaries in a river basin are largely national or provincial and, therefore, do not coincide with the river basin or sub-basin boundaries? how could upstream-downstream benefit sharing from coordinated, basin-wide and adaptive irrigation management be envisioned in such a situation? the scope of this article is thus to provide a scientific and policy documented source of information for a co-design research approach in which academia and stakeholders concur with plans for sustainable irrigation water use in view of integrative resource management in the danube basin. study area: the danube basin we chose the danube basin to assess the current situation of irrigation and its potential future role as an exemplary case study to show the current knowns and unknowns on the way towards a coordinated, basin-wide and adaptive future irrigation management. the danube basin is the largest river basin in the eu (i.e. it covers 801 463 km2 and hosts about 81 million inhabitants) and the world’s most international river basin, being shared by 19 countries. the diverse natural conditions throughout the danube basin impose different shares of croplands in the landscape (fig. 2), favoring or limiting irrigation application decisions where necessary. as such, the relief characteristics in the upper danube basin, till the morava river, favor cropping activities in the plains and low hills of the bavarian depression in germany and in the intramountain plain, on the long rounded hills and in the high piedmont plains at the bottom of the alps of the vienna basin. in the middle danube basin, specifically in the pannonian depression, the agricultural activities are favored by the presence of fertile soils covered by loess, particularly in the large pannonian plain in hungary (i.e. the middle danube plain) which extends in romania, serbia, croatia and slovakia as well (loczy et al., 2012). in the lower danube basin which extends in romania and bulgaria, one of the most extensive agricultural regions of high productivity potential is the romanian plain, including the danube alluvial plain (52 600 km2). it has large areas of fertile soils of chernozem type and a high diversity of ecological conditions (e.g. tabular plains covered by loess, piedmont plains, terraces plains, low subsidence areas, danube terraces which in the western part are covered by sand dunes, etc.) (romanian geography v, 2005). in bulgaria, the relief of the moesian plain, including the danube alluvial plain, turns from flat and hilly in the western part to hilly-plateau toward east. the region is crossed by valleys with high depth phreatic layers, rendering rather difficult conditions for irrigation (stefanov, 2002). rainfall decreases from west to east, from about 700-900 mm to about 400-300 mm. this leads to structural deficits in rainwater availability for agriculture in the pannonian and, even more markedly, in the fig. 2 cropland in the danube river basin, (dataset: ramankutty et al., 2010) 4 dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. romanian plains. these large and fertile downstream areas of the danube basin can improve from irrigation to increase yields by reducing or mitigating water stress in summer and by increasing resilience against droughts, which will most likely be more frequent in a future climate. large irrigation systems had been installed during communist times (i.e. 1960 – 1980s), proving the necessity for irrigation in these regions. they largely turned inoperative, particularly in romania, during the transition period towards market economy (i.e. 1990s), while a possible relaunch would open up opportunities to establish new sustainable irrigation schemes in large parts of the basin. governance schemes are in place on the eu (framework directives), the basin (international commission for the protection of the danube river – icpdr; danube strategy) and on the national, province and county level to manage the water, food, (renewable) energy and land resources. we assume that these multiscale governance schemes contain large untapped potentials for alignment and spatial interconnection. climate change is an important driving force that affects nexus resources and induces strong spatial differences within the danube basin (icpdr, 2013; mauser et al., 2018). temperature increase, variation in rainfall amounts and their changing distribution patterns are expected to cause significant modifications in the hydrological regimes of the danube sub-basins, resulting in more frequent periods of severe low flow conditions and decreasing summer discharges in the upper danube (mauser and hank, 2008; mauser and prasch, 2016) and more frequent, longer and intense drought periods in the lower danube (clavier, 2009). such impacts are likely to affect the water balance of the entire basin and the sub-basins and lead to increasing stress on the water resources, which further result in impacts on actual evapotranspiration and increase of irrigation water demand, while decrease the flow in rivers which are main sources for irrigation (pistocchi et al., 2015; bisselink et al., 2018). at the same time climate change and elevated co2 concentrations will strongly affect the agricultural yield potentials in the basin. on the one hand climate change will generally decrease water availability on the other hand however, increasing co2 levels will improve water use efficiency for most agricultural crops. the net effects on yields can be very diverse regionally and the potentials are not known yet in detail. most likely, the land use and irrigation regimes in the danube basin will be strongly influenced. in view of the above-mentioned arguments, the danube basin is ideally suited for our study because it offers a complex web of (historical) regional needs for irrigation, climate gradients and climate change, multiscale institutional settings, different farming practices in the danube countries, and different economic development dynamics. irrigation and water-food-energy nexus in the danube basin insights on irrigation sector in the danube countries in relation to water-food-energy nexus were derived from profiled literature referring to topics such as: agricultural drought and management, water use efficiency, water scarcity, virtual water, and climate change implications on water resources. furthermore, we documented the european union’s and national existing regulations, norms and future development plans with respect to water management, including irrigation water use. these aspects are described in the section below. eu/danube basin interdisciplinary research projects european commission (ec) signals that water scarcity and drought have become growing challenges for many parts of europe over the last decades, generating increasing costs and damages and potentially leading to changes in irrigation water regimes, particularly in the lower danube (ec, 2009, 2012; pistocchi et al., 2015). water scarcity, drought, desertification and climate change impacts and the associated risks in europe, including danube countries, have been assessed over the last decade in a number of eu interdisciplinary projects (e.g. cc-ware, clavier, see-risk, re-care, impact2c, macsur, drought r & spi) funded by eu-fp6, eu-fp7, erdf or cohesion funds. broadly, this research covers drought risk management topics, with a focus on impact assessments on cropping systems and farmers in most drought-affected regions of europe (gwp cee, 2015; macsur, 2017; siebert et al., 2017), as well as on characteristic drought indices representation under current and climate change conditions (blauhut et al., 2016). the latest projects funded through the interreg danube transnational programmme (i.e. interreg dtp, a funding instrument targeting the danube region in particular), e.g. dridanube dtp, whose objective is the assessment of drought related risks in the danube basin, and camaro-d dtp, with a focus on the assessment of land use impacts on water regimes in the danube river basin, serve as examples of investigating optimum options of land and water integrative management through several case-studies. moreover, the growing signals of water scarcity, which is prospective in the case of the danube basin under climate change (pistocchi et al., 2015; icpdr, 2015; bisselink et al., 2018), suggest a stronger emphasis on the international or regional trade of food and products in the context of virtual water (i.e. the green and blue water used in producing the commodity) concept. for example, the danube basin could shift from a net virtual water importer into a net exporter under particular dietary scenarios considering only the case of the agricultural products (vanham and bidoglio, 2014). a number of european database structures (e. g. euro-cordex and predecessors, carpatclim, ec eurostat and ec joint research center portals) provide domain parameters such as climate variables and impact climatic indices, as well as comprehensive environmental and socio-economic indicators. worth mentioning the fao aquastat dataset which offers statistics and gridded data at 5 minutes grid-cell resolution (about 10 x 10 km2 near the equator) on irrigated areas and areas equipped for irrigation (döll and siebert, 2000; fao aquastat, 2013). however, the need for accurate monitoring of irrigated areas in europe with the support of the global monitoring for environment and security dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. 5 programme (gmes/copernicus) and its fleet of remote sensing satellites is expressed by european commission’s aims towards achieving water use efficiency (ec, 2012). scientific information at regional and national level the contextual literature on irrigation has been informing on the particularities of the irrigation sector in the danube countries, particularly in the lower danube where irrigation has a long tradition. while the syntheses on irrigation remain valuable sources of information in terms of past developments of the agricultural infrastructure, crop suitability and environmental impacts in irrigated areas (grumeza and kleps, 2005; bárek et al., 2009), the local case-studies provide details on the conditions and parameters of various agricultural regions for optimum irrigation schemes, such as timing, watering norms, water use efficiency in irrigated vs. rain-fed conditions, etc. the results of numerous empirical studies and field experiment applications concerning irrigation water use for most common crops under various local conditions in the danube basin are found in the annual series and communications published in the journals and bulletins of specialized institutions, such as the national research institute of agriculture in romania, the agricultural faculties (e.g. scientific papers. series a. agronomy, 2012 – 2017) or the slovak agricultural university (e.g. acta horticulturae et regiotecturae). however, only few landscape scale studies in the danube basin provide evidence on the influence of the changing climate conditions on water resources and agricultural productivity, and in the context of increasing demands for food, water and bioenergy. for instance, glowa-danube project represents an example of integrative assessment of the regional effects of climate change in the upper danube. it is based on an integrative decision support system (i.e. danubia) consisting of various natural based and social science based sub models which allow the design and assessment of complex scenarios for future development, envisaging impacts on water resources (mauser and prasch 2016). likewise, the icpdr case study on tisza river basin, in the middle danube region, stresses the importance of integrated management of water and land resources due to the impacts of agriculture resulted from water abstractions and nitrate pollution (icpdr 2012). moreover, the icpdr report (2017) on the 2015 drought points out that agriculture was by far the most affected sector and in areas with periodical irrigation, such as the marchfeld in austria, water demand was significantly above the longterm average. the report concluded that water scarcity is likely to increase in the danube basin, drought will be one of the future priorities in water management, better data monitoring for agricultural water withdrawals and, enhanced dialogue between the water and the agricultural stakeholders are needed. eu/danube basin regulatory frameworks the regulatory framework for the danube basin management has been constantly developed since the danube river protection convention was signed in 1994 in sofia (bg) by the riparian countries. focusing in the beginning on the quality of the water and environmental protection, it evolved, up to present, toward the integrative management framework of icpdr. the latest river basins management plans in the danube basin represent a common effort of the danube countries to work on and respond to integrated land and water management requirements, considering future water demands and climatic conditions (icpdr, 2015). the water framework directive (wfd) in particular targets long term actions such as protection of waters so as to achieve a qualitatively and quantitatively good status of all waters in europe, including efficiency of water use, adequacy of agricultural practices and coordinated water-pricing policies. likewise, certain eu’s common agricultural policy (cap) subsidies are contingent on meeting the objectives in wfd through cross compliance and agri-environmental measures with the purpose of decreasing the agricultural pressures caused by water abstractions and hydromorphological changes, thus enhancing the synergies between water and agricultural policies (eea, 2012). at the same time, cap aims at ensuring food security, climate adaptation, a competitive and dynamic farming sector and green economy by supporting the economic growth while preventing environmental risks (ec, 2010). it is acknowledged that sustainable agricultural measures can support water management through sustainable farming practices. more efficient water saving irrigation techniques will have to be developed and applied along with sustainable regulatory actions envisioning water use with special attention to water demand to prevent or effectively respond to water scarcity challenges (icpdr, 2015). although the principles of the european water and land use policies are meaningful, their implementation throughout all member states (including danube countries) is a complex and difficult process. it relates to integrative management of resources and active transboundary cooperation in the context of sharing resources among countries. such aspects are not straightforward, but marked by complex trade-offs among sectors or risks induced by market mechanisms which usually are oriented towards achieving greater profits, or by regional particularities (e.g. economic evolution pathways, cultural legacy, governance structures, etc.) which may make particular legislation problematic for one country but suitable for another. nevertheless, achieving cross-sectoral and cross-scale cooperation for an integrative and sustainable resource management is dependent on the political will, stakeholder commitment and working institutional arrangements to manage resource nexus issues (hoff, 2011; allouche et al., 2015). national regulations and development strategies for irrigation in the danube basin countries this section synthesizes the main aspects regarding irrigation management and irrigation future development plans in the danube countries where irrigation has been playing an important role for agriculture and represents central issue for climate change adaptation and mitigation strategies (table 1). http://www.degruyter.com/view/j/ahr 6 dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. discussion on the challenges to irrigation water use in the danube basin irrigation in the reported data on water use reported data, where available, on water use in the danube countries were analyzed in order to get an overview on the level of water demands in the basin, as well as on the possible gaps in data monitoring for sustainable irrigation management. the shares of surface water abstractions from the danube river basin relative to the total surface water abstractions in each country highlight those countries dependent on danube’s water resources given their largest extent in the basin, i.e. hungary, romania, slovak republic, serbia (table 2). however, danube basin’s surface waters are used according to each country’s level of water resource availability, demand and supply endowment facility, ultimately depending on the environmental conditions and the socioeconomic development of the country. table 1 schematic information on irrigation regulatory designs and perspectives in the danube basin’ s countries country current situation (brief note) regulatory instruments for irrigation development perspectives germany de is relatively rich in water resources. recent experience in irrigation due to increasing drought spells. permits are needed to allow for the abstraction of an allotted volume of water for irrigation (germany´s federal water act). no specific development plans for the german part of the danube (i.e. badenwürttemberg and bavaria). however, the federal states make use of the subsidizing options to a very varied degree (bosch & partner gmbh, 2014). czech republic the actual use of the irrigation systems accounts for about 2530% of the area equipped with irrigation which is of 160 000 ha, i.e. 3.65% of agricultural land (trnka et al., 2016). irrigation water is used on the basis of permits for water abstraction; payments are applied for abstractions larger than 6 000 m3/year or 500 m3/month. the rehabilitation of the existing infrastructure and development of new systems are envisaged in view of future increased areas affected by precipitation deficits due to climate change (trnka et al., 2016). slovakia initially covering 321 000 ha (~20% of arable land), the operational systems nowadays can cover 72 565 ha (hydromeliorácie, š.p. report, 2016). the ministry of the environment has introduced a fee with the lowest possible impact for irrigation water consumption (act no. 303/2016). an increase of the irrigated area to 892 000 ha, or at minimum to 700 000 ha, is required in order to prevent climate change effects (koncepcia, 2014). hungary water sources are based on transient waters. during 2009 – 2011 about 70 000 ha were irrigated and in 2015, 128 328 ha (i.e. 2.4% of the agricultural area) (ec, 2015). permits for irrigation are issued by the general directorate of water management / subordinated institutions on the basis of contracts for irrigated areas. to minimize the effects of drought, it is expected that the irrigation area could increase to about 180 000 ha, although there is a great uncertainty about the required water quantities abstracted for irrigation (icpdr, 2012). republic of serbia transient waters are sources for water abstraction for irrigation; the irrigation systems cover a relatively small area of cultivated land (i.e. 105 000 ha out of 2 016 716 ha of arable land) (maep, 2015a). water permits are issued for land owners or suppliers of irrigation water for a certain amount of abstracted water. farmers pay half of the tariffs set out for the irrigation. the irrigation area is going to increase to 350 000 ha by the end of 2030 through rehabilitation of the existing systems and construction of new infrastructures, along with nonstructural measures (e.g. knowledge transfer, consultancy for farmers, etc.) (maep, 2015a). romania it benefits from a large experience in irrigation. during 70s-80s, an extensive irrigation system was installed, i.e. ~ 3 million ha out of 9 389 200 ha (ins, 2015). in the recent past (2009 2016) about 600 000 ha totals the land that could be irrigated (afir, 2017). a yearly subscription for an allotted volume of irrigation water was available until recent to farmers (law no. 138/ 2004, amended by law no. 158/ 2016). presently, the costs for irrigation water (i.e. the costs of water and energy for pumping) are totally subsidized (law no. 133 / 2017). the national programme for the rehabilitation of the primary irrigation infrastructure of the ministry of agriculture and rural development (madr, 2016) stipulates that 2 006 941 ha are going to be suitable for irrigation by 2020. bulgaria built during the 60s – 70s to cover about 740 000 ha (velikov, 2013), the irrigation systems serve today only between 4% and 8% of the irrigable area, i.e. 541 779 ha (ministry of agriculture and food, 2017). permits to abstract an allotted volume of water for irrigation issued according to the water act’s conditions for water availability and sustainable use. the price for the irrigation water delivery service is determined annually by the minister of agriculture and food (decree no 16/20.01.2017). the strategy for the management and development of the hydraulic network and protection from harmful effects of water aims to increase the actual irrigated area by 2030 to 316 580 ha (ministry of agriculture and food, 2016). dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. 7 romania stands out as the largest consumer of fresh surface water for irrigation among the danube countries, considering only the danube river basin resources. however, this aspect is not reflected by the yield levels (e.g. in romania maize achieves a yield of 4 t/ha as compared to 7.4 t/ha in hu; eurostat, 2017). this is related to inefficient irrigation water use due to aspects such as low technical capacity of the exiting irrigation infrastructure, lack of cooperation between the water suppliers and farmers resulting in improper timing and norms of irrigation application, etc. (madr, 2011). in essence, the extensive irrigation systems are characteristic for the large agricultural areas in the middle and lower danube basin, e.g. hungary and romania, where the infrastructure has been planned for large scale irrigation application. the climatic scenarios studies show increasing intensity and frequency of droughts particularly for central and eastern europe (clavier, 2009), thus requiring a careful allocation of water resources specifically in this part of the basin. the data shown in table 2 gives a first overview on the currently available knowledge on the diversity of irrigation in the danube river basin. it conveys two clear and important messages: 1) although all countries extract irrigation water from the common danube water resources, data is largely available only on the national level, no comprehensive and homogeneous data set is available on the irrigation in the danube basin, 2) the reported data is strictly based on registered values of water that is metered for irrigation. it contains no information on how much of this irrigation water is productively used for the purpose to increase yields. from a water-food nexus perspective this aspect is bound to create confusion on how much water is actually consumed by irrigation at a certain location and on how much of the extracted water, which is metered, can in principle be used further downstream because it is not leaving the system. fig. 3 shows the irrigation water pathway from a resource nexus point of view. water for irrigation must be extracted from a river or a groundwater aquifer and is table 2 volumes of fresh surface water abstraction from the danube river basin by country, total and by sectors, in million m3, and as percentage of the country’s total fresh surface water abstraction, in brackets. the percentages in the square brackets represent the fresh surface water abstraction from the danube river basin relative to the renewable freshwater resources existing in the respective country. danube country total gross abstraction public water supply irrigation production of electricity (cooling) de 3 181.70 (11.71%) [6.92%] 59.07 (3.90%) cz 194.54 (13.16%) [6.45%] 35.30 (10.54%) 12.25 (59.96%) 76.06 (11.93%) sk 283.97 (99.12%) [0.35%] 46.38 (95.26%) 12.08 (100.0%) hu 4 956.20 (100.0%) [4.28%] 255.20 (100.0%) 109.29 (106.1%) 3 862.43 (96.13%) rs 1 288.87 (36.31%) [0.74%] 97.35 (48.26%) 40.20 (56.04%) 1 086.25 (34.54%) ro 5 860.46 (100.0%) [15.03%] 606.14 (100.0%) 352.70 (100.0%) 1 050.11 (100.0%) bg 2 931.05 (54.60%) [2.83%] 293.53 (60.11%) 20.42 (7.05%) 2 522.96 (73.18%) source of data: eurostat, http://ec.europa.eu/eurostat/data/database; the data for most of the countries are averaged around the year 2011. the countries were considered based irrigation application relevance for the respective country (see table 1) and on data availability, e.g. no eurostat data for fresh surface water abstraction were available for austria. fig. 3 irrigation water pathway in the context of resource nexus 8 dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. usually transferred to the point of use through open canals. the losses occur in the form of evaporation from the open water surfaces and leaks from the canals. these two losses are distinctly different from a nexus point of view. whereas the water that leaks from the canals stays in the watershed and can in principle be harvested from the groundwater at a downstream location and is therefore not lost to the system, the evaporated water from the open waterbodies leaves the basin as part of the atmospheric circulation and is therefore lost for any alternative use in the basin. the water that is transported on the irrigated fields is metered and serves the basis for the statistics. on the fields, again, access water leaks to the groundwater and stays in the system, whereas (unproductive) evaporation from the ground and wetted leaves exits the system without effect on plant growth. only the water that transpires through the plants, although it is lost to the system, has the desired irrigation effect to support plant growth. inefficient irrigation water use therefore has two aspects: 1) the unproductive evaporation of water, which leaves the system, 2) the unproductive leakage of irrigation water into the groundwater; here the water stays in the system. clearly from a water-food nexus point of view both pathways have to be minimized. nevertheless, there is a fundamental difference between the two pathways, both in the consequences to the system and in the measures necessary to minimize the pathways. this is particularly important when water use issues involve shared waters. therefore, the first pathway (i.e. unproductive evaporation) unnecessarily destroys water resources upstream and deprives the downstream users of water resources that would in principle be available. the second pathway (i.e. unproductive leakage) usually diverts water from surface to groundwater storage and leaves opportunities open for the downstream users. unfortunately, these pathways are not reflected in the metered irrigation water use. this prevents a regulatory and governance framework which can adequately balance water availability and allocation of water to irrigation upstream and downstream and among different countries. framing a transdisciplinary research in the support of a basin-wide irrigation management plan the tendency in the irrigation sector in the danube countries is to increase the irrigated area and to offer legislative and financial support for encouraging the use of the already existing irrigation infrastructure and for the development of new systems. in romania, for instance, increasing the irrigated area from about 0.5 million ha that can be irrigated today to almost 2 million ha by 2020 is an ambitious objective which aims to boost agricultural activities and production, contributing also to climate change adaptation and rural communities’ resilience. in bavaria, although it is not allotted a certain area for irrigation, the expected increase in water withdrawals for irrigation in the context of climate change is already an issue on the decision makers’ agenda. under these circumstances, central questions have to be addressed:  if all middle and lower danube countries implement their plans to expand irrigation, can water availability sustainably meet the created demands?  where in the upstream-downstream context will hot spots of water shortage be created?  what will be the impact of climate change in altering the availability-demand relation in the danube basin?  what role must advance irrigation monitoring systems, which are able to distinguish inefficient irrigation water pathways, and advanced irrigation technologies play to ensure sustainable irrigation and upstream-downstream benefit sharing?  what governance concepts, including irrigation water pricing strategies, are effective and efficient in reaching the goal of maximizing the societal benefit of irrigation water for the whole danube basin? moreover, the paper highlighted a series of issues related to irrigation in the danube basin, such as: no basin-wide irrigation assessment is available for the danube; the statistics express the irrigation water that is metered and not the water that is actually consumed to produce food; the eu legislation with respect to water and land resources, although profoundly integrative in character, is still difficult to be implemented in all danube countries, raising complex resource trade-offs issues; irrigated agriculture in the danube countries is significantly subsidized, fact that might further enlarge the economic and development disparities in the danube basin, although such measures are welcome by farmers; and, climate change impacts on irrigation are only known with a large degree of uncertainty. increased irrigation, profitable agriculture and climate change are common issues for all danube countries. in this context, the question how danube countries can solve irrigation and drought problems in a sustainable way is a transdisciplinary research endeavor as much as it is a cooperation and governance challenge, dealing particularly with the synergies and trade-offs of water for agriculture, hydropower, navigation and domestic use. to this end, the implications of water abstraction for irrigation in the upper danube countries on the availability of water resources for the downstream countries represent a research question that holds multiple cross-sectoral consequences (mauser, 2017). this is connected to the topic of changing virtual water flows within the danube basin, being subject to scenario assessment in order to identify the optimal economic and social resolutions for all danube countries (vanham and bidoglio, 2014). collaborative efforts between academia and various stakeholders at different level in co-designing this type of knowledge is part of a solutionoriented research which goes beyond complex models, systemic and interdisciplinary problems to englobe in the research process developmental objectives, norms and visions which altogether aim at producing legitimate knowledge and guidance for intervention strategies (mauser et al., 2013). considering the above-mentioned considerations on irrigation in the danube basin, we identified 6 interconnected themes for evaluating irrigation water use at a basin scale which could form an integrated research framework (fig. 4). these are summarized below. dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. 9 1) a basin-wide monitoring system that reflects the amount of irrigation water that is actually consumed by the cultivated crops as well as the additional amount of water needed to combat soil moisture deficits. the novel, basin-wide monitoring system can roughly be based on a combination of crop growth modeling and remote sensing time series taken from the available copernicus satellites, in which the observed growth patterns on irrigated and non-irrigated fields are compared with simulations of plant growth and yield, from which real irrigation water consumption is determined by considering available rainfall; 2) climate change impact assessments on danube basin water resources highlighting potential regional hotspots of water shortages and its consequences for irrigation. this part is based on extensive basin-wide simulations of crop growth under current climate and future climate scenarios including co2 fertilization effects and determines the spatiotemporal distribution additional irrigation water demand; 3) the co-design (with relevant stakeholders) of scenarios of future development alternatives and their simulation in order to explore, in a transparent way, feedbacks (positive and negative) among national water policies / management decisions in agriculture (including irrigation), energy, industry, public use and ecosystem protection, with a special emphasis on exploring the mechanisms of upstream-downstream benefit sharing; 4) based on the scenario analysis, the trade-offs of decision alternatives are identified for sustainable water uses based on an active cooperation between stakeholders at different governance levels and academia; 5) derivation of science-based services for basin-wide irrigation management; 6) dissemination of scientific outcomes for informed decision-making at national and regional levels. the above “danube irrigation nexus research framework” relies on sophisticated new monitoring and simulation tools using the available copernicus satellite data streams and smart environmental models. nevertheless, at its core is the co-creation of knowledge on sustainable basin-wide irrigation water management, which is based on an intensive stakeholder cooperation process, which ensures that the practical benefits of a basin-wide nexus approach become transparent to the decision makers and the knowledge is created with the applicability of the results in mind. conclusions the results of our regulatory mapping and literature review exercise for irrigation water use in the danube basin shed light on what is known on irrigation and its future in the basin. it shows the contributions of eu regulations, strategic plans and visions to resource management, including climate change effects on water resources, and the characteristics and conditions of the national regulatory frameworks related to irrigation application in the danube countries. the challenges of the irrigation sector in the context of future developments and the implications for water-food-energy nexus are derived, ultimately leading to a proposed transdisciplinary research framework supporting a basin-wide irrigation management plan. the scientific interdisciplinary projects form a rich heritage of data and conceptual and analytical outcomes proving substantial scientific support to base european resource policies and/or aid countries enabling regulation change towards resource sustainability. however, many of them deal with the impacts on resources by subsystems (e.g. drought and agriculture, water and land use, or energy and water), being difficult to trace the entire fig. 4 outline of the „danube irrigation nexus research framework” for co-producing scientific knowledge for a basin-wide sustainable irrigation management plan 10 dogaru et al. 2019 / journal of environmental geography 12 (3–4), 1–12. chain of synergies and trade-offs within water-foodenergy nexus due to the complex interlinkages between the resources. the research projects do not explicitly approach the issue of irrigation in the danube basin by considering basin’s water availability and resources nexus issues and the trade-offs among them. instruments such as allocation of important national and european structural funds for the rehabilitation of the existing infrastructures, governance and institutional (re)arrangements to ensure irrigation management and support of investments in on-farm irrigation systems were implemented. this is specific for romania, a lower danube country with large irrigation application potential and need. in the upper danube, irrigation increased particularly as a response to changing climatic conditions. according to the future irrigation development plans, the irrigated areas are expected to increase throughout the danube countries, the largest areas being located in the middle and lower danube, affecting, therefore, the water balance of the entire danube basin. the scientific information reflects several key points, highlighting the need for increased trans-national understanding of irrigation issues and implications for water resources management at danube basin level. foremost, there is growing evidence that central and eastern europe, particularly lower danube, is increasingly affected by droughts which under current development trajectories and climate change impacts will inevitably lead to water scarcity problems. water scarcity, which means using more water than naturally renewable, is a driving force of long-term economic damages (icpdr, 2015). moreover, the impact of agricultural drought (i.e. insufficient soil moisture) on crop yields losses is not sufficient investigated to support agricultural sustainable practices, climate change adaptation and integrated resources management. heavy precipitation events and impacts on yield losses and soil are also priorities in some danube agricultural areas. at the same time, large agricultural areas in the danube basin (e.g. romania, hungary) benefit from arable land whose production potentials need to be accurately quantified to be sustainably exploited in view of both future climatic conditions and socioeconomic development pathways. integrative outcomes regarding water consumption and agricultural production and active collaborations between academia and stakeholders for a better use of the available scientific knowledge for proactive decision-making need to be fostered. at present, the proactive measures meant for long-term sustainable development (e.g. enhancing the resilience of the agroecosystems to climatic extreme events) are less envisioned, lagging behind the reactive actions that are taken at times of crises (e.g. compensations for agricultural losses due to drought) (gwp cee, 2015). at the same time, water pricing could play a significant role for the improvement of irrigation water use. the potential physical scarcity of water (e.g. supply is affected by more variability and uncertainty due to climate change), its connectedness nature and its common pool resource character might interfere with efficient resource allocation and lead to market failures (livingston, 1995), e.g. neglecting environmental impacts or underpricing of the resource (johansson et al., 2002). therefore, institutional arrangements have to be set up in order to achieve efficient water use, which means, in an economic sense, to equate the marginal benefits to the costs of the last unit of water used (johansson et al., 2002). supporting efficiency requires policy instruments that foster security and flexibility with regard to water rights and that consider the natural interdependency of water users (livingston, 1995). in this context, the development of a basin-wide irrigation management plan is a way forward to increasing water use efficiency and to sustainable development at large. therefore, this paper outlines a research framework that advocates transdisciplinary studies, entailing integrative results on danube basin’s water-food-energy nexus in which irrigation plays a central role, and where water resources governance could be realized by accounting for the spatial interconnectedness and equitable use of shared resources, aspects that are embedded in the european resource policies and strategies as well as un sustainable development goals. acknowledgements this work was developed within the framework of the glocad network project (global change atlas for the danube region) during 20142017 period, being funded by the ministry of education and research in germany and coordinated by the ludwig-maximilians university in munich and the institute of geography, romanian academy. the authors are grateful to two anonymous reviewers whose comments helped to improve and clarify the content of the article. references allouche, j., middleton, c., gyawali, d. 2015. technical veil, hidden politics: interrogating the power linkages behind the nexus. water alternatives 8 (1), 610–626. anif – national agency for land reclamation, 2017. areas irrigated in the recent past. https://www.afir.info/ (accessed 12 march 2019). bárek v., halaj p., igaz d. 2009. the influence of climate change on water demands for irrigation of special plants and vegetables in slovakia, in: střelcová k. et al. 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(accessed 1 may 2019). vanham, d., bidoglio, g. 2014. the water footprint of agricultural products in the european river basins. environ. res. lett. 9, 1–11. doi: 10.1088/1748-9326/9/6/064007 velikov, i. 2013. development in agriculture and rural areas of bulgaria, friedrich-ebert-stiftung ltd., p.167, belgrad, serbia. http://library.fes.de/pdf-files/bueros/belgrad/1039920131211.pdf (accessed 15 march 2019). zabel, f., putzenlechner, b., mauser, w. 2014. global agricultural land resources – a high resolution suitability evaluation and its perspectives until 2100 under climate change. plos one 9(9), e107522. doi: 10.1371/journal.pone.0107522 http://dx.doi.org/10.1038/nature11420 introduction study area: the danube basin irrigation and water-food-energy nexus in the danube basin eu/danube basin interdisciplinary research projects scientific information at regional and national level eu/danube basin regulatory frameworks national regulations and development strategies for irrigation in the danube basin countries discussion on the challenges to irrigation water use in the danube basin irrigation in the reported data on water use framing a transdisciplinary research in the support of a basin-wide irrigation management plan conclusions acknowledgements references new habitat data of the green-winged orchid (anacamptis morio l.) located in the surroundings of eger, hungary. further data on this protected species of the foothills of the bükk mountains journal of environmental geography 16 (1–4), 102–106. doi: 10.14232/jengeo-2023-44640 issn 2060-467x new habitat data of the green-winged orchid (anacamptis morio l.) located in the surroundings of eger, hungary. further data on this protected species of the foothills of the bükk mountains tamás misik1*, dóra misik-bartók2 1department of environmental sciences and landscape ecology, eszterházy károly catholic university, 1 eszterházy sqr., 3300 eger, hungary 2district office of eger department of public health, government office of heves county, 1 szarvas sqr., 3300 eger, hungary *corresponding author: misik.tamas@uni-eszterhazy.hu research article, received 9 may 2023, accepted 7 august 2023 abstract in 2022, we identified two new habitats of the protected green-winged orchid (anacamptis morio l.) in the bükk mountains, in the surroundings of the city of eger. one of the habitats is in the southwestern steppe meadow of the protected nagy eged hill, while the other one is on a private plot near the village of szarvaskő. a total of 18 blooming individuals were counted in the two sites. in the lower part of the steppe, at the foot of the protected nagy-eged hill (47°97'56"n and 20°34'51"e), we found one well-developed greenwinged orchid already in its flowering stage. it stood out with its smaller size and different flower colour from the lady orchids (orchis purpurea huds.) widespread on the slopes of the mountain. unfortunately, no other roots were found during our survey. the blooming flowers that make up the inflorescence were of the most common dark purple-red color. at the other site, further 17 individuals of the green-winged orchid were identified in a private garden (3,500 m2) in the outskirts of the village of szarvaskő (47°92'02"n and 20°40'58"e). most of the garden is covered by regularly mowed lawn. all of the detected orchids were in bloom and appeared scattered throughout the plot. five larger plants grew at a great distance from one another, while 12 small ones (height: ≤10 cm) developed in a bunch. we had been aware of the presence of the protected orchid species on the plot since 2017, but before 2022 only a maximum of 3 flowering individuals appeared in one specific area of the plot each year. floristic papers have not reported the occurrence of this species either in nagy-eged or in szarvaskő so far. keywords: floristic data, nagy eged hill, southwestern exposure, steppe meadow, szarvaskő introduction the green-winged orchid (anacamptis morio l.; syn. orchis morio l.; bateman et al., 1997) is a springflowering bee-pollinated orchid (johnson et al. 2003). it had been included in the orchis genus until phylogenic studies based on dna sequences demonstrated a closer relationship with the anacamptis genus (bateman et al., 1997). as an element of the european flora, this species is widespread throughout europe: its range covers scandinavia, central and atlantic europe and the mediterranean region (evans, 2011; gaponenko and ivannikov, 2013; stroh, 2007 paušič and kaligarič, 2015). however, during the last decades, in most european countries it has become a critically endangered species (shevchyk et al., 2019). populations of this orchid species have become almost extinct in several countries, for instance in austria, in romania, in slovakia, in slovenia, in serbia, in croatia, in ukraine and in hungary (jacquemyn et al., 2005; kull and hutchings, 2006; elheliebi, 2015). the euro+med plantbase shows that in hungary, the foretype of the species can be found even today (euro+med, 2023). the green-winged orchid is listed as near threatened in the iucn red list of threatened species (rankou, 2011). the green-winged orchid is a species found primarily in open spaces, but it grows in various habitats. the species prefers damp and wet conditions in the habitats; however, it has also been found in dry soil. this orchid species prefers the following conditions: fresh, forest-meadow biotopes with moderately airy, dry clay or wet sandy soils, a great amount of wetness in the rhizosphere with acidic (ph=5.5-6.5) soils, a high concentration of salt (150-200 mg/l), an insignificant content of carbonates, soils that are relatively poor in mineral nitrogen (0.2-0.3 %); furthermore, it occurs from semi-shaded to fully sunlit sites and in general prefers subarid air and a semi-continental climate with moderate winters (shevchyk et al., 2019). in hungary, the green-winged orchid is a widespread species, as several localities have been found both in the western and in the eastern parts of the country. in hungary, it is a lowland and montane species, which, therefore, can be found most commonly in the lowlands, as well as in hilly and low mountainous areas. it grows in both acidic and basic soils, but generally avoids soils with neutral ph. it can also be found in pastures, mowed fields, mountainous areas, sandy and marshy meadows, saline and sandy steppes, dry grasslands, grassy slopes, and open https://doi.org/10.14232/jengeo-2023-44640 mailto:misik.tamas@uni-eszterhazy.hu misik and misik-bartók 2023 / journal of environmental geography 16 (1–4), 102–106. 103 scots pine forests. a farkas (1999) mentioned several documented habitats of the species: the north hungarian mountains, the transdanubian mountains, the mecsek, the villány mountains, the zselic hills, the alpokalja region, the dráva plain, the little hungarian plain and some parts of the great hungarian plain. therefore, one can say that this orchid is a common species in hungary and is recorded also in all the floristic map grids around the city of eger (bartha et al., 2023). consequently, currently it is not rare in hungary, as its estimated population is over one million plants (molnár, 2011). the orchid under study typically produces one inflorescence with approximately 8-20 flowers, each with two stamens. the green-winged orchid is self-compatible, but depends on pollinators for fruit set (nilsson, 1984). plants grow to 40 cm in height; the average height is between 13 and 35 cm. the loose inflorescence is of various colours, mainly purple but ranging from snow white to pink and deep purple. in hungary, the middle day of its flowering usually falls on may 8. the most effective pollinators of the species are the workers of the honey bee (apis mellifera l.); however, in the nyírség region it also reproduces vegetatively (molnár, 2011). the seedling establishment and seed germination in nature are limitedly known, but the green-winged orchid appears to be able to colonise new or recently disturbed grasslands (stroh, 2007). nowadays, intensive land use has a significant impact on the area of distribution of this taxon. with the decline of grazing and reaping, a further decrease in the number of stocks and the individual’s density, already observed in the last two decades, is expected. so far, it has been found in a total of 777 floristic map grids in hungary. it has been detected in 683 grids since 1990; the rate of the decline is 12 % (molnár, 2011). the green-winged orchid is a protected species, with an ecological value of 10000 huf (66/2015. (x. 26.) fm regulations) in hungary. the aim of this study are (1) to present new habitats of the protected orchid species, (2) and to verify the existence of this species in a highly disturbed habitat and a private garden in the region. methods field sampling was carried out in hungary, in heves county, in the bükk mountains in the surroundings of eger and szarvaskő village (fig. 1). we used the latest version of google map to show the distribution of the new habitats of the green-winged orchid (googleearth, 2023). the field survey was performed on 01 and 02 may 2022. on these days, a few individuals of the species were identified without a targeted search. we completed the enumeration with additional data from the literature and some herbaria. the first plot, the nagy eged hill (536 m) has protected status, and it is a famous wine producing site, with the highest altitude terroir. it is located on the southwestern edge of the southern bükk mountains (dobos et al., 2014). the second plot is located in the outskirts of szarvaskő called nyugodó slope. the plot is a private garden with regular maintenance and most of the garden consists of regularly mowed lawn. results in total, 18 plants were recorded in the two different sites in 2022. at the foothills of the nagy eged hill, in the lower part of a steppe meadow, right along a tourist route, a well-developed green-winged orchid (anacamptis morio l.) individual in its flowering stage was identified (fig. 2a). on the protected mountain, it stood out with its smaller size and different flower color from the lady orchids (orchis purpurea huds.) more widespread in the area. no further individuals were found in the area. the gps coordinates of the individual are: 47°97'56"n and 20°34'51"e. the flowers that make up the inflorescence were of the most common dark purple-red color. fig.1 (a) map of the regions of hungary 1:500000 (kercsmár (ed.) 2015), (b) the bükk mountains 1:40000 (bukkhegyseg.hu 2015), and (c) the area of szarvaskő and nagy-eged (googleearth 2023) 104 misik and misik-bartók 2023 / journal of environmental geography 16 (1–4), 102–106. in the outskirts of szarvaskő called nyugodó slope, in a private garden (3,500 m2), located in nyírfa street, we discovered 17 flower stems of the green-winged orchid (fig. 2b). the gps coordinates of this habitat are: 47°92'02"n and 20°40'58"e. the plot has a southeast exposure and it is sloping towards north. all of the identified orchid plants were in bloom and appeared scattered throughout the central part of the plot. as for the specimens, 5 larger plants grew at a great distance from one another, while 12 small ones (height: ≤10 cm), developed in a bunch. we had been aware of the presence of the protected orchid species on the plot since 2017, but before 2022 only a maximum of three flowering individuals appeared in a specific, central area of the plot each year. discussion we collected and analyzed the data found in the literature and data from various herbaria to find relevant information on the habitats occupied by the greenwinged orchid. we focused on the settlements of eger and szarvaskő, in the bükk mountains (fig. 3). vojtkó (2001) listed several habitats of the species around eger and felnémet; for instance, near the city of eger at the rókafarm, cakó top, cigléd side and kerek hill. vojtkó (2001) mentioned the following places in felnémet: gazsi bog, ostoros valley and pásztor valley. however, he did not connect this species to szarvaskő. pifkó and barina (2004) reported the presence of the plant in 5 different points of eger. they are the following: cakó land, mész hill, nyerges hill, the bog of the nyerges hill and the tó bog. the settlement of szarvaskő does not belong to the foothills of the bükk mountains, so naturally, the floristic data on the village were not part of this botanical collection. schmotzer’s (1997) floristic data on the southern and northern bükk mountains did not contain data on the distribution of the green-winged orchid. the same paper mentioned agárdi [vrabélyi (ap. kerner 1875)] and huta meadow [máthé (ap. soó 1943)], both of which are located near eger, as documented habitats of the plant species; as well as collected relevant data from herbaria on the city of eger, at agárdi [vrabélyi 1868.5.6. (egr = the herbarium of eszterházy károly catholic university in eger)] and the pap mountain (vrabélyi 1870.5.18.). schmotzer’s (2015) description on the flora of the foothills of the bükk mountains included 5470 botanical data and described a few habitats, such as agyagos, the császár hill and the top of the kertész valley, as sites featuring the orchid in the vicinity of eger. the publication, which is relevant in several respects, notes that the species appears also in cemeteries in egerszalók and demjén villages, close to eger. also, data on the distribution of the forest, foreststeppe and steppe species of the flora of the heves borsodi plain contained relevant data only regarding the lógó bank near kerecsend (schmotzer, 2019). (a) (b) fig.2 (a) the green-winged orchid on the nagy eged hill on 05.01.2022 and (b) the green-winged orchid in szarvaskő on 05.02.2022 misik and misik-bartók 2023 / journal of environmental geography 16 (1–4), 102–106. 105 conclusions in 2022, two new habitats of the protected green-winged orchid were identified in the surroundings of the city of eger. one of them is the southwestern steppe meadow of the protected nagy eged hill, while the other is a private plot towards the village of szarvaskő. the stems were all in bloom and appeared scattered throughout the plot. floristic works on nagy-eged and on the southern part of szarvaskő ‒ especially on managed private plot ‒ have not reported the occurrence of this species so far. references bartha, d., bán, m., schmidt, d., tiborcz, v. 2023. on-line database of vascular plants in hungary. university of sopron, faculty of forestry, institute of environmental protection and nature conservation. online available at http://floraatlasz.unisopron.hu (in hungarian) bateman, r.m., pridgeon, a.m., chase, m.w. 1997. phylogenetics of subtribe orchidinae (orchidoideae, orchidaceae) based on nuclear its sequences. 2. intrageneric relationships and monophyly of orchis sensu. stricto lindleyana 12, 113–141. dobos, a., nagy, r., molek, á. 2014. land use changes in a historic wine region and their connections with optimal land-use: a case study of nagy eged hill, northern hungary. carpathian journal of earth and environmental sciences 9(2), 219–230. el-heliebi, s. 2015. zur reproduktionsbiologie von anacamptis (orchis) coriophora – bestäubung, fortpflanzungssystem und bestandsentwicklung des wanzenknabenkrauts in der lobau im nationalpark donau-auen. msc thesis, institut für integrative naturschutzforschung, boku-universität für bodenkultur, vienna, 116 pp. euro+med 2023. euro+med plantbase. the information resource for euro-mediterranean plant diversity. online available at http://www.europlusmed.org evans, k. 2011. wild orchids of se england. report, p. 62. online available at https://www.tumblr.com/barbus59/ 106836135457/wild-orchids-of-the-south-east-uk-part-1-of3 farkas, s. (ed.) 1999. protected plants in hungary, mezőgazda kiadó, budapest. (in hungarian) gaponenko, m.b., ivannikov, r.v. 2013. prospects of cultivation of anacamptis morio (l.) r. m. bateman, pridgeon et m.w. chase (orchidaceae) for conservation in ukraine. ukrainian botanical journal 70(5), 635–641. jacquemyn h., brys r., hermy m., willems j. h. 2005. does nectar reward affect rarity and extinction probabilities of orchid species? an assessment using historical records from belgium and the netherlands. biological conservation 121, 257–263. doi https://doi.org/10.1016/j.biocon.2004.05.002 johnson, s.d., peter, c.i., ågren, j. 2003. the effects of nectar addition on pollen removal and geitonogamy in the non-rewarding orchid anacamptis morio. proceedings of the royal society of london series b 271, 803–809. doi https://doi.org/10.1098%2frspb.2003.2659 kercsmár, zs. (ed.), budai, t., csillag, g., selmeczi, i., sztanó, o. 2015. surface geology of hungary. explanatory notes to the geological map of hungary (1:500 000). geological and geophysical institute of hungary, budapest, isbn 978-963671-302-7, p. 66. kerner, a. 1875. vegetationsverhӓltnisse des mittleren und östlichen ungarns und angrenzenden siebenbürgens. verlag der wagnerschen universitats-buchhandlung. innsbruck, 536 p. kull, t., hutchings, m.j. 2006. a comparative analysis of the decline in the distribution ranges of orchid species in estonia and the united kingdom. biological conservation 129, 31–39. doi https://doi.org/10.1016/j.biocon.2005.09.046 molnár, v.a. (ed.) 2011. atlas of hungarian orchids. kossuth kiadó, budapest, 504 p. (in hungarian) nilsson, l.a. 1984. anthecology of orchis morio (orchidaceae) at its outpost in the north. nova acta regiae societatis scientarum upsaliensis 5(3), 166–179. paušič, i., kaligarič, m. 2015. dry grassland land use treatment regime explains the occurrence of the green winged orchid, anacamptis morio (l.) r. m. bateman, pridgeon et m.w. chase in the goričko nature park, ne slovenia. folia biologica et geologica 56(3), 138–148. pifkó, d., barina, z. 2004. data on the flora of the bükkalja. kitaibelia 9(1), 151-164. online available at https://kitaibelia.unideb.hu/articles/kitaibelia_vol91_p151164.pdf (in hungarian) rankou, h. 2011. anacamptis morio (europe assessment). the iucn red list of threatened species. online available at https://www.iucnredlist.org/species/176030/7178502 schmotzer, a. 1997. floristic data on the southern and northern bükk mountains. kitaibelia 2(1), 71–74. (in hungarian) schmotzer, a. 2015. ceratocephala testiculata (crantz) roth and additional data on the flora of the bükkalja. kitaibelia 20(1), fig.3 the identified new habitats (with names and light blue and red placemarks), and data from literature and herbaria (with blue placemarks) of the green-winged orchid (anacamptis morio l.) in the surroundings of eger, hungary (background: googleearth, 2023). http://floraatlasz.uni-sopron.hu/ http://floraatlasz.uni-sopron.hu/ http://www.europlusmed.org/ https://www.tumblr.com/barbus59/%20106836135457/wild-orchids-of-the-south-east-uk-part-1-of-3 https://www.tumblr.com/barbus59/%20106836135457/wild-orchids-of-the-south-east-uk-part-1-of-3 https://www.tumblr.com/barbus59/%20106836135457/wild-orchids-of-the-south-east-uk-part-1-of-3 https://doi.org/10.1016/j.biocon.2004.05.002 https://doi.org/10.1098%2frspb.2003.2659 https://doi.org/10.1016/j.biocon.2005.09.046 https://kitaibelia.unideb.hu/articles/kitaibelia_vol91_p151-164.pdf https://kitaibelia.unideb.hu/articles/kitaibelia_vol91_p151-164.pdf https://www.iucnredlist.org/species/176030/7178502 106 misik and misik-bartók 2023 / journal of environmental geography 16 (1–4), 102–106. 81–142. (in hungarian) doi: https://doi.org/ 10.17542/kit.20.81 schmotzer, a. 2019. data on the flora of the heves-borsodi plain i. distribution of forest, forest-steppe and steppe species. kitaibelia 24(1), 16–65. doi https://doi.org/10.17542/kit.24.16 (in hungarian) shevchyk, v.l., solomakha, i.v., shevchyk, o.v., dvirna, t.s., solomakha, v.a., shevchyk, t.v., fitsailo, t.v. 2019. a new finding of a uniquely large population of anacamptis morio (orchidaceae) on the left-bank ukraine. biodiversity: research and conservation 55, 15–24. doi https://doi.org/10.2478/biorc-2019-0012 soó, r. 1943. preliminary works on the flora of the bükk mountains and its surroundings. botanikai közlemények 40, 169–221. (in hungarian) stroh, p.a. 2007. the current distribution of green-winged orchid orchis morio l. in huntingdonshire (vc31), the soke of peterborough (vc32) and old cambridgeshire (vc29). nature in cambridgeshire 49, 3–10. vojtkó a. (ed.) 2001. the flora of the bükk mountains. sorbus, eger, isbn 963 00 6629 7, 340 p. (in hungarian) 66/2015. (x.26.) fm decree 19/1997. (vii.4.) ktm decree on measures related to confiscated protected natural values, as well as on protected and highly protected species of plants and animals, the range of highly protected caves, and nature conservation in the european community amending köm decree 13/2001. (v.9.) on the publication of plant and animal species that are significant. (in hungarian) https://doi.org/%2010.17542/kit.20.81 https://doi.org/%2010.17542/kit.20.81 https://doi.org/10.17542/kit.24.16 https://doi.org/10.2478/biorc-2019-0012 introduction methods results discussion conclusions references water quality survey of streams from retezat mountains (romania) journal of environmental geography journal of environmental geography 9 (3–4), 27–32. doi: 10.1515/jengeo-2016-0009 issn: 2060-467x water quality survey of streams from retezat mountains (romania) mihai-cosmin pascariu1,2, tiberiu tulucan3,4, mircea niculescu5, iuliana sebarchievici2, mariana nela ștefănuț2* 1”vasile goldiş” western university of arad, faculty of pharmacy, 86 liviu rebreanu, ro-310414, arad, romania 2national institute of research & development for electrochemistry and condensed matter – incemc timișoara, 144 dr. aurel păunescu-podeanu, ro-300569, timișoara, romania 3”vasile goldiș” western university of arad, izoi-moneasa center of ecological monitoring, 94 revoluției blvd., ro-310025, arad, romania 4romanian society of geography, arad subsidiary, 2b vasile conta, ro-310422, arad, romania 5university politehnica timișoara, faculty of industrial chemistry and environmental engineering, 6 vasile pârvan blvd., ro300223, timișoara, romania *corresponding author, e-mail: mariana.stefanut@gmail.com research article, received 3 july 2016, accepted 14 november 2016 abstract the retezat mountains, located in the southern carpathians, are one of the highest massifs in romania and home of the retezat national park, which possesses an important biological value. this study aimed at the investigation of water quality in creeks of the southern retezat (piule-iorgovanul mountains) in order to provide information on pollutants of both natural and anthropogenic origin, which could pose a threat for the human health. heavy metal and other inorganic ion contents of samples were analyzed with on-site and laboratory measurements to estimate water quality. the samples were investigated using microwave plasma atomic emission spectrometry to quantify specific elements, namely aluminium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead and zinc. the results were compared with the european union and romanian standards regarding drinking water and surface water quality. the studied heavy metals have been found to be in very low concentrations or under the method’s detection limit. thus, in the microbasin corresponding to the sampling points, there seems to be no heavy metal pollution and, from this point of view, the samples comply as drinking water according to the european union and romanian recommendations. our findings confirm that the retezat mountains are still among the least contaminated regions in europe and that the ecosystem and the human health is not negatively influenced by water quality problems. keywords: water chemical analysis, surface water quality, heavy metals, mp-aes, retezat national park introduction heavy metals are considered common pollutants of the environment, having both natural and anthropogenic origins (tchounwou et al., 2012; bradl et al., 2005). the rapid development of modern world has accelerated their release into the biosphere (mosa et al., 2016; panagos et al., 2013). some of the chemical species that contain heavy metals can be highly toxic when inhaled or ingested. they can have an impact on almost every organ and system in a living organism, posing a serious threat to the stability of the ecosystems and a danger for the human health (jaishankar et al., 2014; bradl et al., 2005). they constitute the main contaminant category that affects europe, contributing to around 30-35% in soil and groundwater contamination (panagos et al., 2013). besides air pollution, heavy metals have been regarded, in the last decades, the greatest immediate health threat in central and eastern europe (fitzgerald et al., 1998). the influence of metal pollution on the river ecological status in europe is evaluated according to the water framework directive (roig et al., 2016). the retezat national park is located in the western part of the southern carpathian mountain range (romania, hunedoara county). it possesses a high biological value and has thus been added to the unesco’s man and the biosphere reserves network. the park includes 19 peaks above 2000 m elevation and it has been proposed as a model for the conservation efforts in romania and other countries (bytnerowicz et al., 2005). while several studies from the scientific mainstream literature have dealt with the geology and hydrogeology of the area (povară and ponta, 2010) or the composition of mountain lake sediments (catalan, 2015; camarero et al., 2009; rose et al., 2009), studies regarding the composition of surface creeks seem to be scarce or nonexistent. in this work, several springs and streams from the southern retezat were analyzed for the presence of heavy metals and other ions (cations and anions). the tested cations include ammonium (nh4 +), arsenic (as3+), calcium (ca2+), iron (fe2+/fe3+) and other heavy metals (e.g., lead pb2+), while the anions that were searched for 28 pascariu et al. (2016) include halides (chloride clˉ, bromide brˉ, iodide iˉ), nitrite (no2ˉ) and sulfate (so4 2ˉ), all of them being determined according to the chemical methods stipulated in the romanian pharmacopoeia (1993) or by using test strips. the results were supplemented by microwave plasma atomic emission spectrometry (mpaes) determinations for some metals, i.e. aluminium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead and zinc. most of these species are included in the category of heavy metals (duffus, 2002). study area the studied area (fig. 1) belongs to the southern part of the retezat mountains (bytnerowicz et al., 2005), also known as southern retezat (“retezatul sudic” in romanian), and is located on the southern slope of the piule-iorgovanu mountains (ardelean, 2010; povară and ponta, 2010), between 1529 and 1871 m of altitude. the stream water samples (fig. 1) were collected at six sampling points at scorota cu apă and scorota seacă (the headwaters of scorota river) in the upper part of the jiul de vest river basin (iordache et al., 2015; ujvári, 1972). the microbasins corresponding to the sampling points contain active streams with lengths which vary between 100 and 500 m, and with a discharge usually between 2 and 5 l/s. the sampling points were allocated by considering these short lengths and their relative position to the scorota sheepfold: near the sheepfold, which is also the lowest part of the grazing area, and in the higher limit of this area, with approximately 100 m of altitude between the different sample points. from geological point of view, mostly sedimentary rocks cover the surface, like quartz sandstones, marl and marl-limestones, with patches of schists and limestones. the most important soil types are humus-iron-illuvial podzols, humus-silicate soils, brown podzols and brown acidic soils. these mountains are characterized by a rich flora and fauna. subalpine meadows (grassland) predominate, being in contact with the upper limit of the coniferous domain, composed mainly of norway spruce (picea abies). carex and festuca meadows alternate with mountain pine, juniper shrubs and dwarf shrubs composed of vaccinium vitis-idaea and vaccinium myrtillus (bytnerowicz et al., 2005; kern and popa, 2009; mâciu fig. 1 location of the sampling points water quality survey of streams from retezat mountains (romania) 29 et al.,1982; tulucan et al., 1999), as can be seen in fig. 2 (left). the climate is continental and typical for high mountain areas (povară and ponta, 2010). prior to sampling, weather was stable with constant atmospheric pressure. there was no record of rainfall or snowfall that could have produced signs of indirect contamination (e.g., acid rain or residual grazing waste). the list of analyzed samples, together with time, location and on-site measured parameters, are given in table 1. samples 1-3 come from springs which originate in fluvial deposits from non-karst rocks (sandstones). for samples 2 and 3, the measurements were taken near a confluence of two very short creeks, which combine to form a right tributary of scorota cu apă stream. sample 4, corresponding to the highest measured point, comes from a spring localized in noncalcareous detrital rocks; the sampling was done in a ravine with erosional slopes (fig. 2, right). samples 5 and 6 were collected near scorota sheepfold from two creeks that flow over holocene detrital deposits. the catchment is located in the festuca meadows perimeter; sampling sites corresponding to samples 1 3, 5 and 6 are located in the juniper floor, where juniper clusters alternate with festuca meadows. due to the fact that the sampling was performed at the beginning of november, any organic pollution that might have appeared because of grazing should have been washed by precipitations in the two months that have passed since the ending of the grazing period. methods sampling and in situ measurements geographic coordinates and altitudes were established using a magellan meridian platinum mapping gps receiver, while air temperature and pressure were recorded with a portable auriol weather station. sample temperature, ph and electrical conductivity (ec) were registered with a portable hanna hi 98130 combo ph&ec measuring device. nitrites and sulfates were measured in situ using merck test strips (merckoquant® nitrit-test and merckoquant® sulfat-test) (table 1). we have generally followed iso 5667-3 guidelines for sampling. to prevent contaminations, thoroughly cleaned plastic recipients were used (bradl et al., 2005; ogoyi et al., 2011), prepared in the laboratory by protracted soaking with 2 m nitric acid followed by rinsing with double distilled water. they were also conditioned in situ with several aliquots of the water to be fig. 2 environment of the sampling sites (left side: juniper forest and festuca meadows, characteristic for samples 1, 2, 3, 5 and 6; right side: eroded mountain slopes in the case of sample 4) table 1 sampling parameters parameter / sample 1 2 3 4 5a 6a date (day/month/year) 01/11/2014 01/11/2014 01/11/2014 01/11/2014 02/11/2014 02/11/2014 time (utc+2 hours) 12:00 13:00 13:10 16:00 09:00 09:10 geographic coordinates 45°17’57’’n 22°53’23’’e 45°17’55’’n 22°52’57’’e 45°17’55’’n 22°52’57’’e 45°17’57’’n 22°52’30’’e 45°17’53’’n 22°53’33’’e 45°17’53’’n 22°53’35’’e altitude [m] 1620 1759 1759 1871 1533 1529 air pressure [mbar] 842.8 828.3 828.3 817.6 -b -b air temperature [°c] 25 22 22 15 -b -b sample temperature [°c] 4.8 5.4 5.9 4.9 5.0 4.0 ph [ph units] 8.40 7.92 8.02 8.00 8.13 8.18 ec [μs/cm] ~ 10 < 10 < 10 < 10 < 10 < 10 a geographic coordinates and altitude were established using google earth (2015) software; b not measured. 30 pascariu et al. (2016) sampled. after completing this protocol a volume of 350 ml of water was collected. to avoid the loss of elements by adsorption on the walls of the storage recipients, the samples were stabilized by acidification to ph ~ 1 by adding 20 ml of 10% nitric acid (pascariu et al., 2013). laboratory analysis all glassware needed for analysis was washed with 2 m nitric acid and thoroughly rinsed with double distilled water just prior of being used. preliminary analyses were performed on filtrated samples the day after they were collected according to the general procedures stated by the romanian pharmacopoeia (1993). a blank solution (350 ml double distilled water with 20 ml 10% nitric acid) was also prepared in an identical plastic container and tested for comparison. the following aqueous reagents were used: nessler’s reagent (potassium tetraiodomercurate (ii), k2hgi4, and potassium hydroxide, koh) for ammonium, sodium hypophosphite (nah2po2) in hydrochloric acid (hcl) for arsenic, ammonium oxalate ((nh4)2c2o4) for calcium, silver(i) nitrate (agno3) for halides, potassium hexacyanoferrate(ii) (k4[fe(cn)6]) for iron, sodium sulfide (na2s) for heavy metals (e.g., lead) and barium chloride (bacl2) for sulfates. the chemical reactions that use these reagents are stated to have the following detection limits: 0.3 ppm for ammonium, 1 ppm for arsenic, 3.5 ppm for calcium, 0.5 ppm for chlorides, 0.5 ppm for iron, 0.5 ppm for lead and 3 ppm for sulfates (romanian pharmacopoeia 1993). for mp-aes, an agilent 4100 with webintegrated agilent mp expert software was used. the instrument was adjusted using as calibration standard the provided wavelength calibration concentrate for icp-oes & mp-aes (al, as, ba, cd, co, cr, cu, mn, mo, ni, pb, se, sr, zn 50 mg/l, k 500 mg/l) and also an aas standard solution for ca, fe and mg. the following wavelengths (in nm) were measured: al 396.152, cd 228.802, co 340.512, cr 425.433, cu 324.754, fe 259.940, mn 403.076, mg 285.213, mo 379.825, ni 352.454, pb 405.781, and zn 213.857. in contrast to atomic absorption spectrometry (aas), which is based upon the absorption of a characteristic radiation, atomic emission spectrometry (aes) uses the emission of a characteristic wavelength for the determination of the analyte element. plasma emission spectrometry utilizes a plasma as the excitation source for atomic emissions, which, in mp-aes, is formed via the use of a microwave field source. aes belongs to the most useful and commonly used techniques for the analysis of heavy metals, providing rapid and sensitive results in a variety of sample matrices, although the detection limits are higher than those of aas (bradl et al., 2005; higson, 2006). results and discussion the average water temperature was 5.0 °c, the mean ph value was 8.11, while the measured ec value was around or below 10 μs/cm for all samples (table 1). the in situ tests using test strips did not indicate the presence of nitrites or sulfates (nitrite ion concentration less than 1 mg/l, sulfate ion concentration less than 200 mg/l, according to test strips instructions). also, the very low measured ec indicates that the total dissolved solids (tds) must be under 10 ppm (lenntech, 2016). the samples were tested for the presence of ammonium, arsenic, calcium, halides (chloride, bromide, and iodide), iron, heavy metals (e.g., lead) and sulfates. except for a very faint opalescence obtained when sample 1 was tested for calcium, all these tests were negative, an observation that supports the very low measured ec for all samples (table 1). mp-aes results are summarized in table 2, while the drinking water standards from eu (1998) and romanian “law no. 311 from june 28, 2004” (romanian government 2004) are given in table 3 for comparison with the analyzed samples. as can be seen, except for a somewhat increased iron content in sample 1 (probably due to the humus-iron-illuvial podzols, which are present in the area), the studied streams are within the limits specified for drinking water (brad et al., 2015) by all specified standards. the metal contents are generally low and there is no observable trend downstream on any of the elements. the romanian environmental legislation regarding surface water quality, stipulated in “order no. 161 from february 16, 2006” (romanian government 2006), is summarized for the considered ions in table 4. this surface water quality classification is useful in order to establish the ecological status of all marine and continental table 2 mp-aes cation content results, in mg/l sample concentration al cd co cr cu fe mg mn mo ni pb zn 1 * * 0.03 * * 1.61 0.53 * 0.03 * 0.01 * 2 * * 0.03 * * 0.05 1.10 * 0.02 * 0.01 * 3 * * 0.02 * * 0.13 1.84 * 0.02 * * * 4 0.01 * 0.02 * * 0.08 0.18 * 0.02 * * * 5 0.01 * 0.02 * * 0.14 0.88 * 0.02 * * * 6 * * 0.02 * * 0.05 0.54 * 0.02 * * * * under detection limit (< 0.005 mg/l). water quality survey of streams from retezat mountains (romania) 31 table 3 drinking water standards comparative table; all values are in units of mg/l unless stated otherwise (european union, 1998; romanian government, 2004) parameter eu standards 1998 romanian law no. 311/2004 ph [ph units] 6.5-9.5 6.5-9.5 ec [ms/cm] 2.500 2.500 tds # # temperature [°c] # # aluminium (al3+) 0.200 0.200 ammonia/ammonium (nh3+nh4+) 0.50 0.50 cadmium (cd2+) 0.0050 0.0050 calcium (ca2+) # # chromium (cr3++cr6+) 0.050 0.050 cobalt (co2++co3+) # # copper (cu2+) 2.0 0.1* iron (fe2++fe3+) 0.200 0.200 lead (pb2+) 0.010 0.010 manganese (mnx+) 0.050 0.050 magnesium (mg2+) # # molybdenum (mox+) # # nickel (ni2+) 0.020 0.020 zinc (zn2+) # 5.000 chloride (clˉ) 250 250 nitrite (no2ˉ) 0.50 0.50 sulfate (so42ˉ) 250 250 # not mentioned; * is allowed as 2.0 mg/l if the distribution piping material contains copper. table 4 surface water quality classes depending on cation content, as stated in romanian “order no. 161 from february 16, 2006”; units are in mg/l, unless stated otherwise parameter order no. 161 (2006) i ii iii iv v ph [ph units] 6.5 – 8.5 ec [ms/cm] no guideline tds not mentioned temperature [°c] no guideline aluminium (al3+) not mentioned cadmium (cdx+) 0.0005 0.001 0.002 0.005 >0.005 chromium, total (cr3++cr6+) 0.025 0.050 0.100 0.250 >0.250 calcium (ca2+) 50 100 200 300 >300 cobalt (co3+) 0.010 0.020 0.050 0.100 >0.100 copper (cu2+) 0.020 0.030 0.050 0.100 >0.100 iron, total (fe2++fe3+) 0.3 0.5 1.0 2 >2 lead (pbx+) 0.005 0.010 0.025 0.050 >0.050 magnesium (mg2+) 12 50 100 200 >200 manganese, total (mn2++mn7+) 0.05 0.1 0.3 1 >1 nickel (nix+) 0.010 0.025 0.050 0.100 >0.100 zinc (zn2+) 0.100 0.200 0.500 1.000 >1.000 chloride (clˉ) 25 50 250 300 >300 sulfate (so42ˉ) 60 120 250 300 >300 aquatic ecosystems, including rivers and lakes, both natural and artificial. the evaluation of the considered quality elements, like chemical and physical-chemical parameters, can indicate the presence of certain natural environments, minor alterations of these or the degree of anthropic impact, and, respectively, the status of water bodies quality in a certain amount of time. there are five ecological states being defined for natural rivers and lakes: very good (i), good (ii), moderate (iii), poor (iv) and bad (v). according to table 4, the streams corresponding to samples 3-6 belong to class i. an exception could be the stream that provided sample 1, which belongs to class iv according to the iron content. also, according to the lead content, the streams that provided samples 1 and 2 could belong to class ii or iii, but these low measured lead levels may more realistically be accounted for by the mp-aes precision limit. our findings support the previous studies which state that the retezat mountains are among the least contaminated regions in europe (catalan, 2015; catalan et al., 2009). regarding the studied parameters and considering the low levels of dissolved ions, water quality was found to be good or very good. thus, heavy metals do not pose any ecological or human risk in the studied area. conclusions mp-aes, alongside some classical analytical procedures, were used to analyze the water quality of springs and creeks from the retezat national park. for all tested samples, heavy metals were at very low levels or under the detection limit for the chemical reactions employed and the mp-aes method applied. from this point of view, the samples comply as drinking water according to the eu and romanian recommendations. the average water temperature was 5.0 °c, the mean ph value was 8.11, while the measured ec value was around or below 10 μs/cm for all samples, the later also confirming the very small ion content present in the analyzed mountain streams. in the microbasin corresponding to the sampling points, there seems to be no heavy metal pollution. also, no other potential sources of chemical pollution was recorded in the studied perimeter during our survey. acknowledgements part of this paper was presented at the 17th dkmt euroregional conference on environment and health, june 5-6, 2015, szeged, hungary. some of the research was done at the center of genomic medicine of the “victor babeș” university of medicine and pharmacy of timișoara, poscce 185/48749, contract 677/09.04.2015. references ardelean, m. 2010. piule-iorgovanu mountains – geomorphologic study (phd thesis). “babeş-bolyai” university of cluj-napoca, faculty of geography, cluj-napoca, romania. brad, t., fekete, a., şandor, m.s., purcărea, c. 2015. natural attenuation potential of selected hydrokarst systems in the carpathian mountains (romania). water sci. technol.: water supply 15(1), 196–206. doi: 10.2166/ws.2014.092. 32 pascariu et al. 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(ed.) molecular, clinical and environmental toxicology. volume 3: environmental toxicology. springer basel, 133–164. doi: 10.1007/978-3-7643-8340-4_6. tulucan, a.d., tulucan, t.n., beke, l. 1999. alpine karst in romania. acta carsologica 28(1), 139–147. ujvári, i. 1972. the geography of romanian waters. “editura științifică” publisher, bucharest, romania, p. 371 (in romanian). introduction study area methods sampling and in situ measurements laboratory analysis results and discussion conclusions acknowledgements references (microsoft word 4. ny\341ri-kiss 2010.doc) journal of env. geogr. vol. ii. no. 3-4. (2009) pp. 31-36 blown sand movements at kiskunhalas on the danube-tisza interfluve, hungary nyári, d. 1 kiss, t. 1 1university of szeged, department of physical geography and geoinformatics. 6722 egyetem u. 2, szeged, hungary abstract the largest blown-sand area of hungary is located on the danubetisza interfluve. here the most significant aeolian activity took place during the pleistocene, however the aeolian transformation of the landscape occurred also in the holocene and even in historical times. the aims of the study were (1) to reconstruct the relief at different historical periods; (2) to determine the periods of sand remobilisation during historical times; (3) to identify the changing of climatic conditions and possible types of human activities enabling aeolian activity and (4) to specify the spatial extension of sand movements. to reconstruct the spatial characteristic of sand and palaeosoil layers a 3dmodel of the deposits at the archaeological site was created using total station measurements and surfer 8.0 software. in order to determine the exact time of blown-sand movement optically stimulated luminescence (osl) measurements (6) were applied. based on the results, the lowermost sandy-loess layer had a late pleistocene age, on which sequences of palaeosoils and blown-sand layers were formed during the holocene. the spatial extension of the palaeosoils and sandy layers suggest that the relief has changed significantly over historical times. the former pleistocene blowout depression has altered because of both the climatic conditions and the human impact on the environment. blown-sand movements in historical times filled up the blowout depression. the sand sheets reshaped the original morphology and soil properties. today the surface is more elevated and even, the site is covered by dry and slightly humic sandy soils. keywords: environmental changes, holocene, blown sand, osl dating, archaeology, human impact introduction the population, the development of agricultural techniques and the changes in land use caused human induced environmental changes, which became increasingly significant in history. good examples can be found on the danube-tisza interfluve where the change in climatic conditions and the anthropogenic disturbance together caused aeolian activity during historical times. therefore, the original geomorphological setting of the area transformed, and pleistocene forms were reshaped by holocene sand-movements. the earliest blown sand movements on the danubetisza interfluve took place in the inter pleniglacial of the pleistocene (sümegi p. – lóki j. 1990, sümegi p. 2005) and subsequently there was aeolian activity during the middle pleniglacial of the pleistocene after 25 200 ± 300 year ago (krolopp e. et al. 1995, sümegi p. 2005). according to earlier researches on the danube-tisza interfluve the most significant aeolian activity occurred during the upper pleniglacial (borsy z. 1977ab, 1987, 1989, 1991, sümegi p. et al. 1992, sümegi p. – lóki j. 1990, sümegi p. 2005). later, the two cold and dry periods, the older dryas and younger dryas in the pleistocene were convenient for aeolian rework (borsy z. et al. 1991, hertelendi e. et al. 1993) which is supported by radiometric, optical and thermo-luminescence measurements too (gábris gy. et al. 2000, 2002, gábris gy. 2003, ujházy k. 2002, ujházi k. et al. 2003). sand dunes, formed under cold and dry climate in the pleistocene, were gradually fixed as the climate changed to warm and humid during the holocene. however, researchers draw attention to the possibility of sand movement in the holocene too. the warmest and driest holocene phase (boreal phase) was the most adequate for dune formation (borsy z. 1977a and b, 1987, 1991, gábris gy. 2003, kádár l. 1956, marosi s. 1967, ujházy k. et al. 2003), though, certain investigations claim that the second half of the atlantic phase could also be dry enough for the remobilisation of sand (borsy z-né – borsy z. 1955, borsy z. 1977a and b, gábris gy. 2003, ujházy k. et al. 2003). nevertheless, the latest, usually local signs of aeolian activity can be related to various types of human impact. former investigations consider that sand movement could occur during the turkish occupation (16th-17th century ad) and subsequently in the 18th -19th century ad due to deforestation (borsy z. 1977a and b, 1987, 1991, marosi s. 1967). based on archaeological investigations and osl measurements on the danube-tisza interfluve aeolian activity occured in the bronze age (gábris gy. 2003, ujházi k. et al. 2003, nyári d. – kiss t. 2005a and b, kiss t. et al. 2006, 2008, nyári d. et al. 2006a and b, 2007a and b, sipos gy. et al. 2006), then the surface became stable for a long period, until the 3rd-4th centuries ad. as later the climate turned dry (rácz l. 2006, persaits g. et al. 2008) and the anthropogenic disturbance became more significant conditions became suitable for aeolian activity, which is proved by several researchers (lóki j. – schweitzer f. 2001, kiss t. et al. 2006, 2008, nyári d. et al. 2006a and b, 2007a and b, sipos gy. et al. 2006, knipl i. et al. 2007). sand movement was also characteristic in the migration period, especially during the 6th-8th century ad, which was the realm of the avars (nyári d. – kiss t. 2005a and b, kiss t. et al. 2006, 2008, nyári d. et al. 2006a and b, 2007a and b, sipos gy. et al. 2006) subsequent aeolian activity occurred also in the high medieval period (11th-13th centuries ad, lóki j. – schweitzer f. 2001, gábris gy. 2003, 32 d. nyári – t. kiss joeg i/3-4 ujházy k. et al. 2003, nyári d. et al. 2006a and b, knipl i. et al. 2007, kiss t. et al. 2008) and when the cumans inhabited the territory (13th century ad, sümegi p. 2001, kiss t. et al. 2006, 2008, nyári d. et al. 2006a and b, 2007a and b, sipos et al. 2006). the latest aeolian activity occurred in the 15th century bc (nyári d. et al. 2007a, kiss t. et al. 2008). the present research provides evidence on sand movements in historical times caused by changing in climatic conditions and human impact on the environment. the aims of the study were (1) to reconstruct the relief at different historical periods; (2) to determine the periods of sand remobilisation during historical times; (3) to identify the changes of climatic conditions and possible types of human activities enabling aeolian activity and (4) to specify the spatial extension of sand accumulation. study area the 9 km2 large blown sand covered study area is situated on the southern part of the danube-tisza interfluve, northeast from kiskunhalas (fig. 1). the altitude of the area varies between 122 and 138 m a.s.l. low-lying flat areas dominate the southern part, where greater depressions are situated. on the northern part, a higher sandy area characterises the landscape. the forms stretch from nw to se, and clearly mark the direction of prevailing winds during aeolian periods (fig. 2). fig. 1 location of the study area fig. 2 relief of the study area, the archaeological site and the sampling places the 550 m long and 6 m wide, 1.2-2.5 m deep excavated site was located along a future pipeline on the middle of the study area in a blowout depression, providing an exceptionally good example on holocene aeolian reshaping (fig. 2). methods osl measurements the optically stimulated luminescence (osl) determines the last exposure of sediments to sunlight. therefore, the method is especially suitable for identifying the depositional age of wind-blown sands (aitken m. j. 1998). altogether six samples were collected from three profiles. measurements were made on an automated risoe tl/osl-da-15 type luminescence reader at the department of physical geography and geoinformatics, university of szeged. laboratory techniques and measurement protocols can be found (sipos gy. et al. 2009). investigation of archaeological findings by investigating the findings of the site the activities and environment of earlier inhabitants of the area can be reconstructed. previous archaeological analyses (wicker e. 2000, rosta sz. 2007) allowed us to study the morphological situation of findings and to couple historical settlement pattern with landforms. this analysis enabled us to reconstruct the type, intensity and the geomorphological results of human impact. geomorphological mapping the relief and geomorphological map of the investigated area were compiled on the basis of field measurements joeg i/3-4 blown sand movements at kiskunhalas on the danube-tisza interfluve, hungary 33 and 1:10,000 scale topographic maps. first the major aeolian morphological units: erosion-transportation and accumulation zones, the basic morphological features: blowout depressions, blowout ridges, blowout dunes or hummocks, parabolic dunes, sand sheets, deflation areas and the brink lines of dunes were identified. 3d-modelling to model the landscape at different historical periods a 3d terrain model was created on the basis of layers along the archaeological excavation using total station measurements and surfer 8.0 software. results based on the geomorphological map of the area, the northern part of the investigated area represents an accumulation zone, where the most typical forms are blowout depressions, blowout ridges and blowout dunes (hummocks). on the southern part the erosion and transportation zones are situated with unclear boundaries and covered by less of forms, which are predominantly deflation areas, blowout depressions, blowout ridges and sand sheets (fig. 3). fig. 3 geomorphological setting of the study area samples for osl dating were collected from three profiles along the excavated site. based on the results the lowermost sandy-loess layer was formed at 12.7 ± 1.2 ka in the pleistocene, on which a 35-110 cm thick soil evolved during 9000 years in the holocene. according to the osl measurements subsequent aeolian reactivations took place 2.9 ± 0.3, 1.74 ± 0.2, 1.59 ±0.2 and 1.2 ± 0.19 ka and resulted a 30-180 cm thick layer consisted of sand and poorly developed soil layers. sequences of blown-sand layers and soils suggest that the relief of the surface during different historical times was not the same as today. the wind continuously filled up the former blowout depression. later, as the surface was stabilised again, a relatively thick and dark soil layer could develop. fig. 4 profiles, depositions and the osl data however, according to the osl measurements, around 0.59 ± 0.07 year ago aeolian activity restarted and created a 30-100 cm sandy deposit on the top of the layers (fig. 4). discussion the age and depositional data of the profiles were compared to archaeological evidence on the site and in the region (wicker e. 2000, rosta sz. 2007). for the reconstruction of spatial characteristic of land surfaces at different historical periods a 3d model of the layers was created. all these enabled the reconstruction of the type, intensity and the results of human impact on the environment in different historical periods. until the 9th centuries bc a blowout depression was located at the excavated area. its altitude varied between 122-124 m a.s.l. and a very thick soil was developed on the surface (fig. 5). southeast from the blowout depression a higher sand dune was situated, which is still visible today. fig. 5 surface profile: before the 9th century bc as the result of several sand movements, 30-180 cm thick sand layer was deposited (fig. 6). in the 9th century bc (osl: 2.9 ± 0.3 ka) a thin sand layer covered the deepest part of the depression. since then sand movement took place in the subboreal phase, which was 34 d. nyári – t. kiss joeg i/3-4 cool and wet (járainé k. m. 1966, 1969), the role of climatic controls on the remobilisation of sand is certainly insignificant. on the other hand the findings around kiskunhalas from the 9th century bc (wicker e. 2000) provide an evidence for the presence of a dense result of human disturbance at this time. subsequently, until the 2nd century bc soil development occurred. during the 2nd-5th century ad sarmatians inhabited the territory (rosta sz. 2007), who were engaged in agriculture and kept large livestock on the pastures. the excavated sarmatian trenches and wells were found on the elevated surface of the paleosoil, while marks of livestock treading in the deepest part (fig. 6). fig. 6 animal foot prints (foto: istván knipl) these indicate that the low-lying, wet area of the blowout depression was used for watering, while the higher surfaces were pastures or plough-fields. sarmatian animal breeders and farmers with large population meant an intensive burden on the environment, thus the chance for wind erosion increased on bare surfaces caused by over-grazing or ploughing. due to these reasons aeolian activity appeared on the territory in the 3rd and 5th century ad (osl: 1.74 ± 0.2, 1.59 ± 0.2 ka) and the area of the blowout depression was covered by a sandsheet. however, in this case the role of climatic control could be more significant, as this was the time of the “roman warm period”, which generally characterised by warmer and drier weather conditions (rácz l. 2006). in the 8th century ad (osl: 1.2 ± 0.2 ka) aeolian activity was possibly induced by the avars (wicker e. 2000). at this time the climate was cold and dry (rácz l. 2006), being ideal for sand movement especially when anthropogenic impact was superimposed. as a consequence of the sand movement between the 9th century bc and the 8th century ad, the blowout depression was filled up, thus a more homogenous surface developed at a higher elevation (fig. 7). fig. 7 surface profile: 8th century bc subsequently, a longer stable period came without sand movement, which coincides with the generally more warm and wet “medieval warm period” (rácz l. 2006). during this time the surface was stabilized and a humic sandy soil developed (fig. 8). fig. 8 surface profile: 13th century bc people settled down in this area in the árpádian period, between the 13-14th century ad. based on plough marks stretching, from north to south along a 60 m long section (fig. 9), the area functioned as a plowland in the 13th century when a 20-30 cm anthropogenic layer was formed (fig. 10). based on the stockyards, house remains, potteries and bones later it might have been used for animal husbandry as well as for settling down from the turning of 13-14th centuries (rosta sz. 2007). fig. 9 plough marks stretching from north to south (foto: szabolcs rosta) joeg i/3-4 blown sand movements at kiskunhalas on the danube-tisza interfluve, hungary 35 fig. 10 anhtropogenic layer above the plough marks on this palaeosoil, another sand layer can be found (fig. 11), which was formed in the 15th century ad (osl: 596±68 y). the sand movement is probably also the result of human disturbance as a well was found indicating inhabitance. at this time the climate was generally unfavourable for aeolian activity as it belongs to the “little ice age”. fig. 11 surface profile: the 15th century bc thus, the aeolian activity levelled the surface even more on the altitude of 124 m a.s.l., which can be seen today. now the area functions as a plough land and the modern ploughing techniques destroyed the former layers (fig. 12). fig. 12 the surface in 2007 conclusion the holocene morphological evolution of the investigated area is complex. the pleistocene forms were reshaped and transformed, thus at certain locations the original morphology can hardly be identified. remobilisation and reshaping were especially intensive during historical times (fig. 13). the former landscape changed mostly because of the combined effects of climate and human impact on the environment. blown-sand movements in historical times filled up the blowout depression. fig 13 the osl ages and the archaeological relicts of the area sand sheets reshaped the original morphology covered several generations of palaeosoils. today the surface is higher and more even; a dry and slightly humic sandy soil covers the area of the former low-lying and wet blowout depression which was filled up by thick organic sediment and soil. acknowledgments the authors to thank szabolcs rosta and istván knipl for assistance and the archaeological data provided. the authors are also grateful to györgy sipos for providing with the results of osl measurements. the research was supported by the otka k62200 and pd73379 research grants. references aitken m. j. 1998. an introduction to optical dating: the dating of quaternary sediments by the use of photon-stimulated luminescence. oxford: oxford university press, pp. 1-280. borsi z-né – borsy z. 1955. pollenanalitikai vizsgálatok a nyírség északi részében. közlemények a klte földrajzi intézetéből 22: 1-10 borsy z. 1977a. a duna-tisza köze homokformái és a homokmozgás szakaszai. alföldi tanulmányok 1: 43-53 borsy z. 1977b. a magyarországi futóhomok területek felszínfejlődése. földrajzi közlemények 1: 12-16 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(eds.) kiskunhalas története. vol. 1, kiskunhalas: thorma jános múzeum, pp. 57-58, 98-99 spatial diagnosis and conceptualisation of greening plan of seme-podji, benin (west africa) journal of environmental geography 16 (1–4), 22–30. doi: 10.14232/jengeo-2023-44431 issn 2060-467x spatial diagnosis and conceptualisation of greening plan of seme-podji, benin (west africa) abdel aziz osseni1, gbodja houéhanou françois gbesso1*, ghislain c. akabassi2, bokon a. akakpo3 1horticultural research and management of green spaces unit, laboratory of plant, horticultural and forest sciences, school of horticulture and management of green spaces, national university of agriculture, ketou p.o. box 43, benin 2faculty of agronomic sciences, laboratory of applied ecology, university of abomey-calavi, cotonou, benin 3west african service centre on climate change and adapted land use (wascal), climate change and human habitat (cc&hh), federal university of technology, minna, niger state, nigeria *corresponding author, email: fr.gbesso@gmail.com, tel: +229 97609378 research article, received 20 february 2023, accepted 24 april 2023 abstract conservation and sustainable management of natural resources are increasingly recommended in decentralized territories. the most effective approach for this process is the participation of local communities because their knowledge is valuable in policy implementation. the study aims to propose a sustainable management model of a territory based on the needs of communities in order to conserve the natural resources in the sèmè-podji municipality in benin, west africa. local knowledge and community’s needs have been used in association with gis technics to make a diagnosis of the territory and propose a land use map for the municipality. the spatial diagnosis revealed an anthropization of the land cover, with a predominance of agro-systems, built up areas, croplands and fallow which represent 80.03% of the total area of the municipality. the marshlands which mostly serve as a refugium and support biodiversity represent 5.42%. the proposed plan showed that 84.79% (p ˂ 0.001) of socio-professional needs are explained. therefore, the proposed actions were related to the restoration of ecological continuity, creation of new green recreational spaces, the protection of marshlands, the management of natural protected areas and the creation of fuel wood tree plantations. the current information can contribute to a sustainable and inclusive landscape planning for such municipalities, like our study site at sèmè-podji in benin. keywords: green space, natural resources, participative cartography, land planning, sèmè-podji, benin introduction the importance of natural resources in human daily lives has been widely demonstrated around the world and the conservation of these resources depends on how people interact with them (peterson and fisher, 1977). in this context, the lack of an adapted planning policy leads to environmental and natural resources degradation and raise the attention of development actors (dallimer et al., 2012). globally, the territory of forests was reduced by 40% due to commercial agriculture, and by further 33% to provide agricultural lands for livelihood (fao, 2020). in africa, fao (2020) estimated that the annual rate of forest loss was around 3.9 million hectares between 2010 and 2020. thus, it can be recognized that human pressure on forest resources is important and it is imperious to identify the responsible communities and the actions to implement for the forest conservation in order to contribute to the sustainable economic and social development. in benin republic, the situation has the same trend, but with a high demand for forest products for the population daily uses. in the wetlands of the country in south, in particular at ramsar sites 1017 and 1018, current wood needs are estimated to be more than 50 million m3, and could increase until 2027 (yo et al., 2018). however, these environments form the basis of local biodiversity, which provides ecosystem services. with an aim to maintaining them, benin has adhered to the ramsar international convention adopted in 2000 on wetlands in order to halt the degradation of their ecosystems and limit the reduction in their areas (hunyet, 2013). despite these efforts, we still witness the overexploitation of natural resources in these environments. moreover, the implementation of environmental projects aiming to save natural resources and lands usually fails due to the non-involvement of local communities (amadou siako et al., 2021). in urban cores where resources are limited and subject to high pressures (kpedenou et al., 2016), the desire to preserve biodiversity is reflected in the design of planning scheme that set out priority actions to promote (hand et al., 2016). thus, municipalities are committed to preserve biodiversity through urban planning policies that are more respectful of nature, opting for ecological management of green and natural spaces (cáceres et al., 2015). the town of sèmè-podji is a transitional area between two city’s municipalities in benin such as cotonou and porto-novo. in recent years, the municipality of sèmè-podji has seen a considerable increase in its inhabitant (insae, 2016), given the advantages it offers in terms of residential comfort, economic activities and its strategic position between the two cities. ecologically, the sèmè-podji territory is mostly a wetland area included in the ramsar site 1018 https://doi.org/10.14232/jengeo-2023-44431 mailto:fr.gbesso@gmail.com osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. 23 (abe, 2010), and has been listed as biosphere reserve of the lower ouémé valley since 2020. these assets endow the municipality of an area of interest for natural resources conservation specially mangroves (padonou et al., 2021). however, the urban expansion, the economic development activities and the agriculture along the riverbanks constitute land anthropisation objects, thus hindering the vision of sustainability in which this town is embedded (ryan et al., 2017). furthermore, the exploration of the gulf of guinea's blue woof showed a connectivity between various water bodies and rivers from badagri in nigeria through benin and togo to accra in ghana (hunyet, 2013). unfortunately, the filling in of water circulation corridors and water pollution by industrial discharges and household solid waste (brun et al., 2018), create a fragmentation of ecological continuities (wolch et al., 2014), and consequently disrupt the functioning of local ecosystems (diédhiou et al., 2020). in addition to environmental problems, there is the almost total lack of green spaces, urban gardens for recreation and nature that can play a role in attractiveness and health comfort. likewise, aspects related to green spaces are often neglected and sometimes limited to the creation of pleasure or recreational gardens in cities. yet greening is a determining factor for the sustainability of cities and can help to anticipate the problems of pollution, loss of biodiversity and environmental degradation in general, by ensuring the availability of ecosystem services to people (osséni, 2021). for these challenges, it is important to identify the natural areas around the hydrographic network within this town that could be managed or protected to maintain biodiversity in situ and conserve natural resources in general. this strategy is even more effective when it takes into account local communities’ involvement (shibia, 2010). therefore, within the frame of the presented research we aimed to answer the following questions: what are the favorable advantages of land use for the conservation of natural resources in the sèmè-podji municipality? how people's perceptions can contribute to the sustainable development of the territory's natural resources? thus, this study proposes an investigation applying a participatory approach, and to give a suggestion on the way of development or restoration of the influence of communities in the choice of natural spaces, with a view to the preservation of natural resources and control of the territory (shrestha et al., 2010). data and methods study area belonging to the department of ouémé (south-east of benin republic) and to the atlantic coast, the municipality of sèmè-podji is located between 6°19'59'' and 6°27'34'' north latitude and between 2°27'42'' and 2°42'34'' east longitude (fig. 1). according to the latest territorial division, the municipality of sèmè-podji covers an area of 250 km² and it is subdivided into six boroughs (agblangandan, aholouyèmè, tohouè, sèmè-podji, djèrègbé and ekpè). the municipality counts 222,701 inhabitants. the major socio-cultural groups in this area are the xwla and the seto (insae, 2016). sèmè-podji has a wet tropical climate (subequatorial climate) with annual rainfall estimated at 1100 mm/year due to cyclical disturbances under the influence of the coastal wind, which makes this town one of the wet areas in southern benin. the average fig. 1 map showing the location of the study area and its land use and land cover 24 osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. temperature is about 27°c with a high relative humidity. two rainy seasons (usually from april to july and september to november) and two dry seasons (month of august and december to march) characterize the area. in this coastal plain of benin, the characteristic soil type is hydromorphic. the hydrographic network is well supplied and defines a continuum between the atlantic ocean, the lagoon of porto-novo, the ouémé river and the lake nokoué (fig. 1). the plant associations belong to the coastal guinean phytogeographic sector. despite that the biophysical conditions of this area are favourable to the development of natural ecosystems, there is a progressive disappearance of natural habitats due to the pressure exerted by local populations. gis and remote sensing methods spatial data were used to understand the spatial configuration of the municipality's territory in relation to its potential for natural resources to be developed for green and natural spaces. thus, topographic maps (scale: 1:1.200,000) were used for georeferencing and to support landscape analysis. then, the 191-56 and 192-56 landsat satellite imagery scenes of the december 2021 period were used to classify the land use units. the december period was selected because during the dry season the phenological contrast between the different land use classes is the greatest (justice et al., 1985; fisher et al., 2006; simonetti et al., 2014). a pre-processing was carried out on the topographic sheets and the satellite image. the sheets were georeferenced (reference system: wgs84 utm 31n) and digitized. geometric and radiometric corrections, increase colour contrast and enhancement were made on the satellite image to eliminate atmospheric biases, easy superimposition on topographic sheets and to facilitate processing and interpretation (leboeuf et al., 2015). envi 5.3 software was used for image digitalization. an image interpretation is carried out in order to obtain a recognition of the land cover classes by creating digital layers of control points on the image. then, coloured compositions in true colours were made by combining the bands (tohozin, 2016). a supervised classification of the satellite image was therefore carried out through the selection of the training plots and the use of the maximum likelihood algorithm which is based on the principle of calculating the probability of belonging of a pixel to a given class or not. a confusion matrix was generated to assess the quality of the classification in its overall accuracy. finally, the data from the digital processing was vectorized and exported to arcmap 10.7 to be integrated into the gis for the production of maps, area calculations and statistical analyses. questionnaire survey the survey data comes from a questionnaire on resource users to collect their perception and opinions on the choice of projects corresponding to the natural potential of the territory of their municipality. the outline of the questionnaire used concerns on (i) the restoration of ecological continuities; (ii) the creation of green recreational spaces; (iii) the protection of natural wetlands; (iv) management of existing protected areas; (v) restoration of local forest plantations and (vi) creation of harvest plantations. in total, 220 respondents in 7 socio-professional categories were interviewed. there were mostly farmers and stockbreeders (40), craftsmen (40), hunters and traditional healers (10), traditional chiefs (10), traders (40), office workers (40) and fishermen (40). although it was not a representative random sampling (baribeau, 2009), the choice of these socio-professional categories was made according to their influence on natural resources. then, a focus group was carried out with the stakeholders to control the divergences around the opinions expressed on the developable natural resources. the data of the social survey were entered into excel spreadsheet. response rates provided by the employment categories on the perceptions of green and natural spaces were calculated. an analysis of variance was carried out in order to understand the spatial perception of natural resources and box diagrams were performed. moreover, the opinion of these socio-professional categories on the potential natural resources that could be developed in the form of green and natural spaces was subjected to a chi 2 independence test. this test was carried out on the response rates provided by individuals in each category of respondents made it possible to verify whether there is a relationship between these employment categories, with regard to the accommodation options offered. then, a factorial analysis of the correspondences was made to appreciate the level of dependence of these two variables. finally, a field survey was carried out to validate actors’ proposals according to the characteristics and potential of area biodiversity included hydrographic potential, ecological continuity and coastal biodiversity. during this stage, gps and land use maps were used to georeference waypoints and track the sites suggested by the communities to host these projects. this analysis allowed to build a shared vision of greening which can be translated into a development of green spaces planning in the municipality. results spatial diagnosis for developing green spaces in the municipality of sèmè-podji the spatial analysis of land use and land cover in the municipality of sémé-podji resulted in five land use classes, such as swamps, agrosystems (plantations), crop lands and fallows, water bodies and build up areas (fig. 2). the field observation showed that agrosystems were consisted of plantations such as coconut trees, palm, and firewood trees such as eucalyptus camaldulensis. the greening areas included marshlands, tree plantations and farmlands. these green areas were bordered by water bodies including the atlantic ocean, the lagoon of portonovo and the lake nokoué. finally, the residential areas were along the coast and the shores of lake nokoué. in the study area, the plantations (agrosystems) occupied the largest area (6,168.14 ha). this was followed by built-up areas (5,964.10 ha). the mosaics of crop lands and fallows covered 5,812.39 ha and water bodies, about 3,254.58 ha. osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. 25 finally, the marshlands covered 1,215.07 ha covering the smallest area of the municipality’s territory (fig. 3). local communities highlighted the following perception on the availability of green spaces in the municipality (fig. 4). according to their opinion, the green recreational areas were almost scarce, and the existing natural areas were not accessible to the population, due to the long distances and the difficulty to cross. the marshlands were almost ignored during the green space planning activities. only the beach areas fulfilled the recreational function in the municipality. the important vegetated areas were located in the northern part of the municipality and were specifically dominated by mangroves, but they are not accessible as green spaces. these perceptions varied significantly in the municipality and according to socio-professional category (f = 111.7; p = 0.008). therefore, a participative typology on the needs for sustainable green space development was drawn up for the municipality. vision of the stakeholders on the potential development of green and natural spaces in the municipality of sèmèpodji the opinion of the population of the municipality of sèmè-podji on the sustainable management of their territory through the development of green and natural spaces were collected. the socio-demographic profile of the respondents is presented in table 1. most of the farmers and breeders who gave responses were men (92.5 %) and only 7.5 % of them were women, with an average age of 40.1 ± 10.7 years. among them, 10 % had a university level, 42.5 % had reached secondary level and 47.5 % had a level lower than or equal to primary school. most of the craftsmen were male (72.5 %), but every forth was female (27.5 %), with an average age of 36.7 ±11.93 years. among them, 7.5 % had a university level, 45 % had reached the secondary level and 47.5 % had the primary level. the interviewed hunters and traditional healers were all men, with an average age of 52.7 ± 8.51 years. among them, 20 % had a university level and 10 % had reached secondary level and 70 % had a level less than or equal to primary school. fig. 3 territory of the various land cover classes at sèmè-podji fig. 4 variation in responses on the availability and distribution of green and natural spaces fig. 2 land cover in the municipality of sèmè-podji in 2021 26 osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. the traditional leaders were all also men, with an average age of 61.2±7.68 years. among them, 10 % had a university level and 40 % had reached secondary level and 50 % had a level less than or equal to primary school. the traders interviewed were constituted of 77.5 % men and 22.5 % women, with an average age of 41.4±8.83 years. in this group, 12.5 % had a university level and 32.5 % had reached the secondary level and 55 % had the primary level. most of the workers were men (90 %) and only one tenth (10 %) were women, with an average age of 34 ± 5 years. half of this group had university level and the second half high school level. finally, the fishermen are composed of 87.5 % men and 12.5 % women, with an average age of 37.6±12.75 years. in this group, nobody had university degree, but 42.5 % had reached the secondary level and 57.5 % have had the primary level. these characteristics testify to the relative maturity of the respondents to provide reliable information, and to highlight all the view points on the subject. thus, six major points can summarize stakeholder perception in sustainable management of their territory through the development of green and natural spaces. over one third (39.5%) of the respondents thought about the restoration of ecological continuity through green and blue woofs of the municipality. over half of them (54.1%) proposed to create recreational green spaces such as urban gardens and parks close to the core of the town. according to 57.3% of the respondents maintaining and integral protection of natural wetlands can be made in the perspective of biodiversity conservation. moreover, 55.45% of the people thought to create buffer zones around natural protected areas to develop friendship activities to the conservation. over one third of them (35.9%) bent over on the restoration of planting forests. finally, 64.54% thought about the creation of fuel wood plantations for daily and domestical uses. there is significant dependence between the perception and the employment categories (χ²: p-value ˂ 0,001). the diagram on employment categories and development proposals (fig. 5) represents the distance between two variables indicating their degree of similarity. the eigenvalues extracted by the first two factorial axes are 55.78 % and 29.01 %, corresponding to a total inertia of 84.79 %, which makes it possible to use the results to draw reliable conclusions. thus, the interpretation of this figure informs on the factorial axis 1 (f1), a strong contribution of employment categories such as civil servants, craftsmen and farmers in the establishment of a planning logic. on factor axis 2 (f2), there is a strong contribution from fishermen and traders. the projection of the coordinates in the system of factorial axes makes it possible to distinguish three development tendencies. a first trend that brings together traders and workers around the creation of green spaces for recreation and the management of protected areas. their choice is justified by the importance they gave to plant cover in the sustainability of the natural resources of the sèmè-podji municipality. a second trend which brings together craftsmen and farmers around the restoration of forest plantations, the creation of harvest plantations and the protection of wetlands. according to this group of actors, the availability of ecosystem services from plant resources, in particular the mangrove, is a major concern for the populations of this municipality. the third tendency consists in restoring ecological continuities and it was exclusively supported by sinners. because the latter believe that the blue frame which constitutes the support of their activities is strongly split and anthropized. it is table 1 sociodemographic profile of the respondents employment categories variables modalities proportions (%) famers and breeders age 40.15 ± 10.7 sex m 92.5 f 7.5 education level university 10 secondary 42.5 primary 47.5 craftsmen age 36.77 ±11.93 sex m 72.5 f 27.5 education level university 7.5 secondary 45 primary 47.5 hunters and traditional healers age 52.7 ± 8.51 sex m 100 f 0 education level university 20 secondary 10 primary 70 traditional leaders age 61.2±7.68 sex m 100 f 0 education level university 10 secondary 40 primary 50 employment categories variables modalities proportions (%) traders age 41.45±8.83 sex m 77.5 f 22.5 education level university 12.5 secondary 32.5 primary 55 workers age 34 ± 5 sex m 90 f 10 education level university 50 secondary 50 primary 0 fishermen age 37.65±12.75 sex m 87.5 f 12.5 education level university 0 secondary 42.5 primary 57.5 osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. 27 also noted that the opinion of traditional healers and breeders is close to this third trend, but without much significance. the above data have led to the conceptualisation of a master plan for green and natural spaces development that was illustrated by figure 6. indeed, the sustainable management of natural resources by local communities in sèmè-podji should follow this plan. fig. 5 positioning of stakeholder perception and the employment categories of sèmè-podji. red color: employment categories; blue color: proposed land planning discussion spatial configuration of the territory: a natural asset for the greening of the municipality of sèmè-podji the identified land use classes at sèmè-podji are also characteristic of southern benin (kidjo et al., 2011, lederoun, 2015), thus the results of this study could be applied in other areas as well. the three main land use classes in terms of areas are the agrosystems including plantations (27.51%), built-up areas (26.60%) and mosaics of crop lands and fallows (25.92%). these land uses classes reflect the high land anthropisation in the municipality. this finding corroborates with brun et al (2018) who realized that the municipalities belong to the country's wetlands and specifically in those of ramsar site 1018 undergo high land mutation in profit of built up areas, agricultural areas and tree plantations. appropriation of the spatial configuration through participatory discussion with local communities and field verification were decisive not only for natural resources conservation but also for the choice of actions to be carried out for sustainable development implementation. it is acknowledged that the approach is widely used in spatial diagnosis studies (diédhiou et al., 2021) and highly recommended for the establishment of protected areas (chan et al., 2014). people in sèmè-podji therefore reflected six major greening management and development activities that could be integrated into their daily practices. this led to the dissipation of all susceptibility to sabotage or exclusion of certain categories of actors. this step should guarantee the fig. 6 conceptual map of green and natural spaces of the municipality of sèmè-podji created based on the vision of the local people 28 osseni et al. 2023 / journal of environmental geography 16 (1–4), 22–30. development success (shirkochidi, 2013, forrester et al., 2015). however, the implementation of the ambition may require the guidance of local authorities and decision makers who are in charge for integrating conservation projects into the development plans. the relief of the municipality is a flat with dense hydrographic network, thus, the development of green and blue infrastructures could not be difficult (sahraoui et al., 2016). the ecosystem is characterized by wetland (lederoun, 2015) and the membership of ramsar site 1108 and lower ouémé valley biosphere reserve network constituted an asset for the conservation (brun et al., 2018). according to shrestha et al. (2010), the conservation and development of these ecosystems are essential for the sustainable development of the land. on one hand, this promotes local biodiversity and makes ecosystem services available (adanguidi et al., 2020). on the other hand, it requires stakeholders to implement a management framework that may specify a strong participation of local communities (coldwell & evans, 2018) with the definition of measurable monitoring indicators over time. stakeholder view on option choice for landscape planning in sèmè-podji discussions between stakeholders enabled to clarify the context and the need to manage resources that were previously used without precautions in order to reach a compromise and alternative solutions in the forms of use (ballet, 2007). thus, out of the six development proposals, four are supported by more than half of all stakeholders. these are the creation of green spaces for recreation, the protection of wetlands, the management of protected areas and the creation of harvest plantations. this assumes that the resource needs of the communities are directed in priority towards the areas that will host these developments (shibia, 2010). indeed, it was observed that a strong contribution of the actors was noted around the options on which their activities depend on. for example, the restoration of ecological continuities, exclusively supported by fishermen, constitutes proof that they are aware of the state of degradation of the blue wefts, and the need for their restoration. taking these opinions into account is therefore an opportunity to begin a process of balancing the resources availability and their use by populations (ryan et al., 2017). thanks to this approach, the hope of sustainable development of the territory is possible in the sèmè-podji municipality, with the specificity of taking into account the beneficiaries concerns (haaland and van den bosch, 2015; lubis and langston, 2015). elsewhere, all the proposed management actions seem relevant and likely to contribute to solving problems of availability or accessibility to plannable resources. this is why the positioning of the areas to be developed is made on suitable sites and capable of meeting the objectives set. for instance, recreational green spaces are positioned on exposed land, near or within settlements to reduce the effect of mineralization in urban centers. hence, it is important to take into account the socio-professional categories in order to identify needs by affinity (amadou siako et al., 2021). while fishermen advocated for the restoration of ecological continuity in order to facilitate the circulation and availability of fisheries resources, farmers proposed the establishment of tree plantations and the restoration of forest plantations. these actions aim to compensate land degradation caused by any human activities. such results prove the existence of stakeholder awareness on the impact of their activities on the environment (ilboudo et al., 2020), and therefore the need to find alternative solutions (jennings et al., 2016). the results may be justified by a people commitment to contribute to the sustainable implementation and management of development proposals (acharya, 2004). these initiatives can also show that community involvement helps to strengthen territorial cohesion, increase people's well-being and health, and ensure sustainable development (fao, 2017). in addition, it will enable the community to address contemporary challenges related to attractiveness, connectivity, mobility, adaptation to climate variability, conservation and sustainable management of ecosystems, and employment. conclusion this study enabled us to understand the spatial configuration of municipal territory of sèmè-podji in southern benin through a participatory drawing and field verification approach. this approach allowed the deconstruction of old practices and an awareness of the sustainable management of natural resources. thus, the different greening area types were described and a development proposal was made in the perspective of conserving biodiversity and making the territory more attractive. at the end of this exercise, a conceptual master plan for the development of green and natural spaces, integrating the needs of the communities and the requirements of conservation, was proposed. however, there is a need for political will to support its integration into the development plan of the municipality. references abe (agence béninoise pour l’environnement), 2010. projet de gestion communautaire de la biodiversité marine et côtière. mise en place de la base des données géo-référencées sur la zone côtière et les zones humides. phase 3. 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(urban sprawl and restructuring of the city of porto-novo). phd thesis, université d’abomey-calavi. (in french) wolch, j. r., byrne, j., newell, j. p. 2014. urban green space, public health, and environmental justice: the challenge of making cities “just green enough”. landscape and urban planning 125, 234–244. doi: 10.1016/j.landurbplan.2014.01.017 yo t., adanguidi, j., zannou, a., padonou, e. 2018. evaluation des besoins en bois des populations au niveau des zones de mangroves des sites ramsar 1017 et 1018. (evaluation of the wood needs of populations in the mangrove areas of ramsar sites 1017 and 1018). fao, bénin online available at https://www.fao.org/documents/card/es/c/i8541fr/ (in french) https://core.ac.uk/download/pdf/38629451.pdf https://doi.org/10.1016/j.landurbplan.2014.01.017 https://www.fao.org/documents/card/es/c/i8541fr/ introduction data and methods study area gis and remote sensing methods questionnaire survey results spatial diagnosis for developing green spaces in the municipality of sèmè-podji vision of the stakeholders on the potential development of green and natural spaces in the municipality of sèmè-podji discussion spatial configuration of the territory: a natural asset for the greening of the municipality of sèmè-podji stakeholder view on option choice for landscape planning in sèmè-podji conclusion references flood risk in szeged before river engineering works: a historical reconstruction journal of environmental geography journal of environmental geography 9 (3–4), 1–12. doi: 10.1515/jengeo-2016-0007 issn: 2060-467x flood risk in szeged before river engineering works: a historical reconstruction csaba szalontai university of szeged, department of geology and palaeontology, egyetem u. 2-6, h-6720 szeged, hungary *corresponding author, e-mail: csaba.szalontai@gmail.com research article, received 3 may 2016, accepted 10 september 2016 abstract szeged situated at the confluence of the tisza and the maros rivers has been exposed to significant flood risk for centuries due to its low elevation and its location on the low floodplain level. after the ottoman (turkish) occupation of hungary (ended in 1686), secondary sources often reported that the town was affected by devastating floods which entered the area from north, and a great part of the town or its whole area was inundated. natural and artificial infill reduced the flood risk to some extent after the town had been founded, but in the 19th century flood risk was mitigated by river engineering and the reconstruction of the town. the town relief was raised by a huge amount of sediment, which makes it difficult to determine the elevation of the original relief as well as the exact flood risk of the study area. however, some engineering surveys originating from the 19th century contain hundreds of levelling data in a dense control point network making possible to model the relief of the whole town preceding its reconstruction and ground infill. based on these data, we prepared a relief model which was compared with the known data of the 1772 flood peak, from which we deduced that 60% of the town must have been inundated before it was filled up. as there could have been 50-100 cm thick natural or artificial ground infill since the 11th century, the original natural relief can be gained by deducting these data. based on this deduction, the extent of inundation centuries ago could reach 85%, which means almost total flooding. keywords: szeged, relief, flood, inundation map, settlement history introduction szeged was the third most important town in the medieval kingdom of hungary, right after buda and fehérvár. the town was founded at the mouth of two big rivers (the tisza and the maros), so its most important potential was being an ancient junction of trading and military routes. this potential was well-utilised by its inhabitants. the economic and urban development of the town starting in the 11th and 12th centuries resulted in being granted certain privileges by the king, and szeged became a free royal town by the 14th century. a common principle in urban geography and in archaeology is that river mouths are one of the most important urban settlement factors. rivers do not only provide an active connection with other parts of the world, but they also have other important features, for example, according to biogeography, rivers may guarantee tranquillity for the inhabitants of the surrounding area. the confluence of the tisza and the maros rivers exhibits similar advantages. their valleys have been important routes connecting the middle east through the balkan with the central and the northern parts of europe, and as such, they made the travel of ancient people and the spread of different economies, raw materials, lifestyles, and material cultures easier. this advantageous geographical situation should have enabled the foundation of significant human settlements at the mouth of the two rivers or the nearby riverside in different archaeological periods, which would also have meant several significant and big archaeological sites. as opposed to this, the lack of archaeological findings and sites points to the fact that the area was mainly uninhabited before the 11th century. neither archaeology, nor history have researched its reasons in detail so far, the presented ambiguity has not been resolved. we finished a complex land use evaluation some years ago, which also enabled us to add a new approach to settlement history (szalontai, 2014). our findings indicated that the reasons for the area staying unpopulated for such a long time must be connected to the disadvantageous physical geographical features of the tisza-maros confluence. a detailed analysis of archaeological sites and road networks proved that the tisza-maros confluence was not controlled by the ancient people directly on the riverside, but from a bit farther away. while the river mouth proved to be rather unfavourable, the water system situated 8 km farther away from the tisza, which we are going to describe later, provided more favourable conditions. the ancient routes crossing the carpathian basin met here, too. by controlling the fords, the confluence of the two rivers could be overseen every period, and the more favourable physical geographical features of these places provided more peaceful life than the river mouth. high flood risk and low elevation were those two unfavourable features that hindered human settlement here the most before the 11th century. the research of historical floods has been boosted by new findings both in national and international studies for two decades. climate and environmental history research as well as flood research have gained more and more attention. our primary aim was to reconstruct floods events 2 szalontai (2016) by the systematic analysis of primary and secondary sources as well as architectural monuments. in addition, flood-induced environmental, economic, social, architectural, and settlement historical effects and consequences of certain flood sites were studied in detail (brázdil and kotyza, 1995; kiss, 2011; rohr, 2007; glaser, 2008). our previous researches aimed at identifying and classifying those landscape characteristics of szeged which help us understand the history of szeged and its surrounding area. we also intended to provide the basics for the development of a great and comprehensive settlement history of szeged and its neighbourhood that is based on a new approach developed by the combined efforts of different sciences. the present study is the continuation of the previous work (szalontai, 2014a). our current research questions are the followings: 1) what was the degree of flood risk at the tisza-maros confluence and szeged in the centuries (and millennia) preceding the reconstruction of the town and the beginning of the river engineering works at the end of the 19th century? 2) what was the flood risk extent of medieval szeged? 3) what influence did it have on the habitation of the area? 4) how often was the area inundated by the tisza? 4) where were those higher grounds that remained dry even during floods so they could ensure survival chances? 5) how did all these features influence human settlement? the above mentioned questions are closely connected to the research interests of archaeology and settlement history as the structure of the inhabited parts of szeged was basically determined by the connections between surface water and topography. these two features designated those morphological sites that were suitable for permanent settlement. by answering the above mentioned questions, we can identify those places that are suitable for human settlement. we also aimed at studying why the area of the present-day town was not populated before the 11th century (in the so-called hungarian middle ages), and why there are no such archaeological findings and sites that would signify the presence of permanent or, at least, frequentlypopulated settlements at the strategic point of the tiszamaros confluence. our previous research proved that the centre of the settlement was not situated along the tisza before the hungarian middle ages, but it was situated on the high floodplain areas of the water system surrounding the town in an 8-km diameter (maty-ér/maty creek, fehértó/white lake, fertő-láposa/fertő marsh, etc.). more significant human settlements were founded on the banks of the tisza only from the 11th century (szalontai, 2014b). finally, we also aimed at finding out whether there are hills in the area which are usually not affected by floods, but they are so close to the surrounding surface water that they can support life. study area szeged is the county seat of csongrád county, the largest city and the regional centre of southern hungary. it is closely situated to the hungarian-serbian border, and it is located on the boundary of two microregions: the southern tisza valley and the dorozsma-majsa sand ridge (fig. 1). the area is the lowest-lying region of hungary, its geomorphology is characterised by the relatively small number of macroand mesoforms (mezősi, 1984). its surface forms have relatively small relief (0-2 m/km2), and they are mainly of fluvial origin. the average relief is between 77-79 m asl, flood-free areas can only be found at a height of 81-82 m asl on the natural levees and the edges of fehértó. a greater part of the area belongs to the low floodplain of the tisza, which also surrounds the city of szeged. the three small islands of the city rise above the surroundings as residual surfaces. basically, the hydrography of the study area is determined by the tisza and the maros rivers as well as some smaller streams along the tisza (szillér, jánosér/jános creek, tápai-ér/tápai creek). the river maros hardly affected the features of the right bank of the szeged landscape, except when its flood dammed up the water of the tisza. the tisza is characterised by two annual floods, which are often likely to last for half a year because they subside slowly. it also means that the land along the river is inundated almost continuously. as the medieval part of szeged lies in a basin-like area, the somewhat higher ridges along the tisza prevent floodwater from flowing back into the main river channel, which results in longer floodings. the second important water network around szeged (maty-ér, fehértó, baktó) has an 8-to-10-km-wide fig. 1 the location and map of the study area, demonstrating the recent and the medieval residential areas flood risk in szeged before river engineering works: a historical reconstruction 3 diameter, and it totally surrounds szeged. the two water networks have different flood risk characteristics. the maty-ér, fehértó, and fertő-láposa receive water input from the kiskunság sand ridge (homokhátság) lying between the danube and the tisza. this water input includes both surface and subsurface water flows, which fill the pools, basins, and channels along the boundaries of the sand ridge. these water flows are slow, static, and of little or no dynamics, they reach the tisza from beneath szeged, and they cross the natural stream channels without any obstacles. they have no flood risks in general. this water network is accompanied by unflooded ridges, and the arable lands found here are of the best quality. as opposed to this, the water network situated on the east is connected to the dynamically changing gauge height of the tisza, and its parts pose a regular and devastating flood risk due to the two annual floods of the tisza. the relationship of szeged and the tisza is totally different from the usual river-settlement relationship, where every change occurring on the river affects the structure and the safety of the accompanying settlement. secondary sources documenting floods in szeged have never reported that the tisza would have flooded the town by stepping over its banks in the city. some documents say that the embankment situated on the outer arch of the city-side of the river was washed away, and they also mention that the eastern wall of the fortress standing directly on the riverbank was destroyed by a flood. but there is no data proving that the city would have been totally flooded. the tisza always floods the city from the north. the right bank of the tisza to the north of szeged is accompanied by a 30-km-long and 2-to-4-km-wide low floodplain which used to carry flood flows downstream. the three small islands where the oldest parts of szeged were founded are situated on the low floodplain with an average height of 1-1.5 m. floods usually flowed around these islands: one part of the flood flow passed round from the eastern area of the town, the other part passed round the islands from the north and the west, and they returned to the main channel of the tisza beyond the town further downstream. in addition, the island of felsőváros (upper town), which is one of the ancient city parts, was divided by several smaller streams which carried water from the low floodplain downstream into the tisza. these streams also allowed bigger floods to inundate even these older parts of the city. the above mentioned characteristic of the city’s location meant a relatively high flood risk, which was further strengthened by unusually high floods. data and methods methodology in order to answer our research questions, we had to reconstruct the hydrographic and geomorphologic environment preceding the land use changes that occurred in the 19th century. by reconstructing the original natural circumstances, we could also get an insight into the circumstances that characterised the different archaeological periods. a detailed study of the original relief and geomorphology is greatly complicated by the fact that the number of the sources is very scarce, which makes the research object very difficult to investigate. it is obvious that our primary task is not the investigation of historical sources, instead we have to focus on preparing geological surveys/bores that cover the entire area of the city in the greatest possible number, and we have to prepare the model of the original terrain based on these data, and, finally, we have to display historical changes with the help of the so-prepared model. since such a model is not available for us at present, we are forced to make use of historical data and reconstruct the original relief of the city with the complex analysis of the available historical sources. although the historical sources provide useful general information about the structure and the relief of the city, they do not abound with accurate data. even the great number of available secondary (written) sources (certificates, travel literature, military reports, etc.) do not contain data on topography. in case they do, they usually emphasise the lowland character of the landscape, and they rarely mention the "öthalom" hills (literally five hills) which are residual surface elements with an average of 12-15 meters. the geographical names of the area may contain names with the word "mount", but they are not of morphological origin, they refer to former vineyards. flood descriptions often mention flood free (dry) islands as well as floods flowing through most of the town without any obstacles. the research was made further difficult by another characteristic of szeged. the city was completely destroyed in the 1879 flood, and, during the rebuilding of the city, its residential areas were filled up with a considerable amount of land lifting the relief but also forever concealing any traces of the original terrain. therefore, in order to investigate our questions concerning settlement history, we have to reconstruct the geomorphology characterising the area before 1879. then, we will be able to identify those city parts which were inundated or usually dry by analysing flood data. filling up the inhabited parts of szeged and the basins between them with soil was a known practice before the 19th century, which resulted in a gradual decrease in the size of the flooded areas. however, the enormous work that began in 1879 surpassed all previous landscape-changing work and was considered a rare and unique process both in hungary and in europe. its primary purpose was to reduce flood risk, and in order to do so, the ground level of the downtown area was going to be raised to the height of 822 cm compared to the 0 cm of the stream gauge of the tisza, which corresponds to 81.92 metres above the baltic sea level. there is no doubt, however, that the entire area of the downtown was not intended to be covered by a homogenous layer. the final version realized was even simpler, in fact, only roads and streets were filled in while the gardens and yards of the houses were no, so there were level differences up to a meter within relatively small distances, such as a house and the street in front of it, which has characterised szeged since then. so, while the streets are artificially infilled and lifted terrains, the elevation of the gardens and yards of the houses did not change essentially (kuklay, 1880; lechner, 2000). a 3-4-meter-thick or even thicker layer was filled in only into former pools and surface streams, but the entire area is characterized by a 1-2-meter-thick layer (kaszab, 1987). the thickest infill in the three ancient parts of szeged can be found in palánk (city), while the thickness of the infill is not significant in alsóváros (lower town) and 4 szalontai (2016) felsőváros (upper town). a new city structure was developed during the reconstruction. the new structure was characterized by a network of boulevards and avenues, all of which lay higher than their surroundings, the ideal infill height was only kept along the road network. as a result, all side streets rise toward the main streets even nowadays. the natural or artificial lifting of the terrain level of populated areas is not an unknown phenomenon in european towns. it was a well-known practice even in different archaeological periods, which practice resulted in distinctive, interdependent settlements built on each other. it is a natural phenomenon that settlements, especially cities, having been inhabited for centuries or millenia, have several meters thick infill layers (puskás, 2008). in moscow, for example, this layer is 2-5 meters thick, but natural depressions may also have a 20-meter-thick infill. thus, three typical geomorphological forms can be created in cities: excavated (hollow, negative), graded (levelled) and accumulative (cumulative, positive) (puskás, 2008; farsang and puskás, 2009). the resulting infill can be sediment of natural origin, or soil-like material, and can be artificial material (debris, gangue, waste, etc.). due to the infill of the city, we have to look for maps that were prepared before the reconstruction. it led us to investigate the topographical data of those handwritten or printed maps that were created before the end of the 19th century, which finally helped us to prepare the topographical reconstruction of the historical town centre. our previous research did not make use of these maps, although more of these scaled city maps that were prepared before the 18791890 city reconstruction contain elevation data. their importance is also great, because only these maps contain exact data about the original (i.e. preceding the reconstruction of the city) topographical features of the area so they are essential for the topographical reconstruction. reducing flood risk was a regularly recurring need and demand in the 19th century szeged, but to plan this, a general survey of the area had to be done first, with a special attention to surveying elevation. otherwise it was not possible to start planning river engineering. thus, the first such map was created in 1830 (map 1, buday 1830), but the overall survey took place only a few decades later when, due to the 1879 flood, the destroyed city had to be completely rebuilt (maps 2-4, barilari et al., 1879, heller, 1880, kuklay, 1879). the consistent and accurate use of elevation data was made easier by 45 iron rods that had been installed as fixed points, and which were intended to promote mapping and rebuilding the city (map 5, halácsy, 1879) (halácsy, 1879; bertalan, 1884). after digitizing the maps having been collected during the research, they were georeferenced, then their elevation data were visualized in an eov system using a gis program, and they were also recalculated to the present value of meters above the baltic sea level (m asl). no compiled city maps depicting the iron rods were made, but each iron rod had a very accurately drawn on-site sketch, which made it possible for us to identify their position as accurately as possible. therefore, we could locate each reference point and its elevation on the georeferenced city map. when identifying the original terrain characteristics of the area before the reconstruction and the infill, we also had to pay attention to determine the ground level associated with the elevation data, because elevation data were measured in meters above the adriatic at the end of the 19th century. the baltic baseline is 0,675 meters higher than that of the adriatic baseline, i.e. the absolute values of the baltic heights are that much smaller than the values of the adriatic heights. there was one independent reference point in szeged, to which all architectural plans were aligned: it was the 0 point of the stream gauge of the tisza river (73.70 m asl) (vágás, 1991). the reason why it is important to emphasise 0 as a reference point is that, for example, when giving the thickness of the infill layer, this thickness was given compared to the 0 point of the stream gauge. six meters of infill does not mean six meters of soil, it means that compared to the 0 reference point of the tisza, the level of the terrain was lifted with 6 meters. that is, the tisza 0 point + 6 m + 74.37 m above adriatic sea level -0.675 m = 79.7 m above baltic sea level. after the terrain reconstruction, the collected elevation data were compared to the peak values of the floods, then by depicting them on a map we were able to locate those areas which were more likely to be inundated when a higher flood occurred. to do so, we utilized the flood data which were less influenced by landscape-changing human activities. it means using those data which originate from the time when floods occurred in a natural (non-engineered) riverbed, flood control works did not hinder flood flow, and floodwater returned to the original river channel naturally. these requirements are necessary because archaeological and historical flood risk cannot be compared to such floods of which causes or flow were influenced by significant human activities. therefore, useful and credible data can only be gained from the times preceding river engineering. thus, we used the data of the 1772 flood as our standard flood level data, which peaked with 630 cm (80 m asl above the 0 point of the tisza stream gauge in szeged). it was not the biggest flood szeged had to suffer, but it was one of the last floods which was neither caused nor influenced by human activities, and there were accurate data on the highest flood level. there were bigger floods in the 18th and 19th centuries (1851: 80.61 m), and there were even higher average flood peaks between 1772 and 1850 (80.11 m asl), but we deliberately underestimated the extent of the potential risks a little bit (fig. 2). fig. 2 data of the highest floods on the tisza (m asl) (vágás, 1991) we carried out the following analyses with the data of the studied maps. we indicated the elevation data on the original and the georeferenced maps one by one. we divided the measured points into 3 groups on the basis of flood risk in szeged before river engineering works: a historical reconstruction 5 the highest flood water level in 1772 (630 cm over the 0 point of the tisza stream gauge = 80.00 m asl): inundated points; saturated points, which are situated 20 cm higher than flood level; flood-free (dry) points. subsequently, we performed the same process, but we subtracted 50 cm from the 19th century elevation data assuming that it equals with the amount of natural infill of the area between the 11th and the 19th centuries. based on these data, we divided the elevation data into three groups again. finally, we simultaneously visualized all data of the five maps by copying them into one file, then we carried out the above mentioned classification again. we also carried out an analysis where we calculated with a 100-cm-thick infill since the 11th century settlement. in order to provide easier orientation, we indicated the contemporary major road network (avenues and boulevards) as well as the earliest settlement structure of szeged on the original map. the detailed description of the applied historical maps map 1 (buday, 1830) is one of the most accurate and detailed maps from the first half of the 19th century, which depicted the outline of all surface water on the town structure, and both the height of water level and that of the walking level were given everywhere. the data were given in viennese feet / inch units, and the then highest flood peak data of the year 1770 were also given in the same units. a total of 70 elevation data were recorded, 44 of which were numbered. data measured in the streets, on the water level of eugenius ditch and its trench are also included in the elevation data (fig. 3a,b). map 2 (barilari et al., 1879) depicts the entire area of the city, its street network, street names, all houses, and the data of 203 measured points. the survey was carried out mainly during and after the flood receded. slope calculations fig. 3 location of inundated and flood-free points in the city a) on the basis of buday (1830); b) on the basis of buday (1830), calculated with 50 cm infill; c) on the basis of barilari et al. (1879); d) on the basis of barilari et al. (1879), calculated with 50 cm infill; e) on the basis of heller’s map depicting boring sites (1880); f) on the basis of heller’s map boring sites (1880), calculated with 50 cm infill 6 szalontai (2016) were done in the inner area of the city to determine elevation differences, and the elevation layer plan of the city was developed on the basis of these calculations (kulinyi, 1901). elevation values were given compared to the 0 point of the tisza stream gauge (fig. 3c,d). map 3 (heller, 1880) depicts the ground-plan of szeged as it was before the flood. the works were organized by b. kuklay, a royal assistant engineer appointed to help the royal commissioner of szeged, and b. zsigmondy engineer, who also evaluated the data (bertalan, 1884). there are 63 boring points on the map, which were drilled with augers between april 4, 1879 and december 15, 1880. measuring points were designated to gather data about the entire area of the city, but first of all the three major city parts, especially the central squares. additional data were collected on such sites which had hydrographic, topographic, or town-planning importance (e.g. mars square and vicinity). the map also includes the drilling profile of the "geological cross-section of lajos tisza boulevard artesian fountain 1: 2500" as well as the section drawings of the "geological layer plan of the royal town of szeged". the eight sections have scales, the elevation of the surface (above the tisza 0 point marked with a line and text as well) is also written on the surface (e.g. +6.75) (fig. 3 e,f). map 4 (szeged, 1879) depicts the entire area of the city, street network, street names, all buildings and land lots. areas covered by water were indicated with blue colour. elevation values were given compared to the 0 point of the tisza stream gauge. the data come from the 1879-survey of kuklay, in which a total of 110 points were measured. in several cases, it happened that he measured at the same location as the data indicated on map 3 (e.g. at the two corners of the same street), but the values did not correspond to each other. as a point definition of these places is no longer possible, we treated both values as authentic and included them into our database (fig. 4a,b). finally, map 5 (halácsy, 1879) depicts the points (87 pieces) that were placed out for triangulation in order to help mapping and rebuilding the city, among which 45 pieces were cast iron rods and 42 were marked wooden posts (halácsy, 1879; bertalan 1884). the iron rods were marked with roman numbers from i to xlv, and each of them had two designated elevation data: one indicated the elevation above the 0 point of the tisza stream gauge, the other one indicated meters above the adriatic (fig. 4c,d). a number of outskirt points were also designated by elevation data. the work was carried out in july-august 1879, when the city was still partly inundated, and there were lots of ruins. each rod and post had an own data sheet which contained a few lines in handwriting about their exact location, the property where they were placed out or they were the closest to, and each property was marked with the number of the respective rod or post. in addition, a 1: 1000 scale sketch was also prepared depicting all of the important landmarks, rods, and posts as in a plan. we continued to survey the extent of flood risk on the basis of the maps mentioned above. we know a lot of floods from the history of the city, so we have to classify the area as having high flood risk on the basis of its historical data already. however, only a detailed analysis of the data can answer the question whether it was always true for the entire city or there were dry, flood-free spots in the flooded area. fig. 4 location of inundated and flood-free points in the city a) on the basis of kuklay’s map (1879); b) on the basis of kuklay’s map (1879) calculated with 50 cm infill; c) location of inundated and flood-free points in the city based on the number of iron survey posts a) based on halácsy’s map (1879); d) on the basis of halácsy’s map (1879), calculated with 50 cm infill flood risk in szeged before river engineering works: a historical reconstruction 7 results the topography of szeged those anthropogenic activities that shape the downtown area of contemporary szeged have been present for nearly a thousand years. landscape transformation is likely to have begun in the early settlement times when people started to change the terrain in order to securely possess central areas. it was not a major influence on the landscape back then because it was not a primary goal to change the functioning of the natural environment. the inhabitants' will to adapt to nature was still stronger than the force to change the environment. the second phase is the post-ottoman city-forming period when two types of landscape changing activities took place. first, there was a conscious and significant reconstruction of the city structure (e.g. building eugenius ditch which was a fortification system around the inhabited parts of the city). second, there was an increasing demand for more and more area which also facilitated stronger landscape changing activities. this period had a stronger impact already but it had little impact on the landscape and topography yet. however, former depressions around the islands were started to be infilled, and the surface of the islands was also subject to levelling. in the third phase, the settlement structure became stable by the middle of the 19th century, and, in addition to the already existing landscape changing activities, the city experienced a significant external impact in the form of recurring floods of the tisza river. hundreds of houses collapsed in the inundated city, and after the flood retreated, the ruins were certainly used locally for grading, for example, or for levelling elevation differences. the 1867 flood had the greatest influence on the city: this period saw the reconstruction and the infill of the city's inhabited areas to reach the ideal level as well as the infill of the inner part of the city. by analysing the database of the five maps previously described, we can see that the elevation values varied between 77 and 83 m asl (fig. 5) by the 19th century. one of the outstandingly high data among the 83 m asl values definitely refers to the height of a flood control dam, so it is not a relevant data. fig. 5 height distribution of the survey points (m asl) in the database only a few data were included in the extreme range, 55.24% of the points were shorter than 80 meters (the flood peak of the tisza was 80 meters in 1772). if we also add those data which are in the high-risk data range of 8081 m, then we can see that a significant part of the city, i.e 81.59 % of the measured points can be found under the critical 81 m asl. the highest values (above 82 m asl) typically occur in a narrow stripe along the tisza, which values clearly indicate initial bank dikes and natural levees. in addition, these high values often appear along the eugenius ditch (an earth trench built as fortification at the end of the 17th century) too. the mean of all points is 79.85 m asl (fig. 6). unfortunately, the elevation data of map 1 cannot be used here as its lowest points indicate such channels and pools that were either temporarily or permanently covered by water. the purpose of its creation was not the levelling of the city, but the survey of the water-filled pools, therefore the measuring points do not show the relief of the city. the highest points of the survey can be found either along the tisza or on the city side of eugenius ditch, which points designate artificial dikes along the water. the results correspond to the known data of the topography of the city well. earlier reconstructions (reizner, 1899; kaszab, 1987; blazovich, 2002) reached the same essential conclusion. j. reizner proved very early that szeged was founded on those three islands which we knew as palánk (city), alsováros (lower town) and felsőváros (upper town) later. he was the first to utilize scientifically the results of the drillings that had been carried out 20 years earlier, and he evaluated the data not only from a geological point of view, but also in terms of settlement history. topographic data (fig. 7) also show that the different parts of the city and the area between them were divided into several small pools that were permanently covered by water (called as "csöpörke" in szeged). they were regularly filled with water during floods, and it took a long time for them to dry up completely, so it was very difficult to utilize the suitable parts of the islands. all three islands are residual surfaces located directly on the riverfront. their slightly higher surfaces by the river can be defined as narrow natural levees which are characteristic of meandering channels (kohán, 2003; molnár, 2011). the edges of the islands that are farther away from the tisza gradually sink toward the direction of the lower terrains, so the area beyond the islands becomes deeper, and closed pools do not let flood water flow back to the river. those parts of the city that are situated even more distant from the tisza may lie even deeper, the elevation difference may reach up to 1-2 meters compared to the levees. this drainless area character was the reason for the 1879 flooding to downflow so slowly; it took a half year to get rid of the water in the inhabited parts of the city, and even then steam pumps had to be used. but this nature was the cause of another common phenomenon: several-daylong rainfall could cause serious aerial floods in the city (lechner, 2000). 8 szalontai (2016) fig. 6 location of inundated and flood-free points a) on the basis of all height points depicted on the map; b) calculated with 50 cm infill; c) calculated with 100 cm infill the geomorphological features of the islands were also different. the middle island (downtown) was the highest of the three islands. other parts of the city which are usually situated farther away from the central part of felsőváros (upper town) lie lower than the rest of the city. obviously, it also means that these parts of the city were inundated first when flood waves from the north arrived. present day rókus and makkosháza are also characterized by lower terrain, but they were not inhabited in the middle ages. a significant part of alsóváros (lower town) is also considered to be low-lying save its southern end where the elevation of the surface reaches that of the palánk (fig. 7). fig. 7 relief models of szeged before the great flood a) on the basis of map data; b) calculated with 50 cm infill; c) calculated with 100 cm infill flood risk of szeged according to scientific literature, flood-proof settlement level is marked at 6 meters above the 0 point of the tisza stream gauge (nagy, 1957), which is 79.70 m asl in the case of szeged. for this reason, the research assumes that prior to 1879 those parts of szeged which lay below 77.32 m asl were hardly habitable, while large areas of the city lay either at or below 75.32 m asl (vágás, 1991). the newly processed data clearly show that a high flood would not inundate about half of the city by the end of the 19th century. however, it is clear that it could hardly have been valid in previous centuries or millennia, and already in the early middle ages the city had very high flood risk. if we do not take the 50-100 cm thick infill originating from urban flood risk in szeged before river engineering works: a historical reconstruction 9 planning into account, the elevation of the measured points reduces, and, therefore, the number of inundated points greatly increases. these data and results spectacularly demonstrate that the low-lying terrain of szeged, which characterized the city before the reconstruction, meant extremely high flood risk, and virtually the entire territory of the city was equally affected. however, this risk continues to grow if remember the simple fact that it is not just inundation that causes damage, but also those seemeingly dry city parts are greatly affected where the soil is saturated from beneath, furthermore the waves caused by the wind could also pose further damages on the dry surfaces. flood damage does not end at the water level, however, we had to define damaged area in our present study so we considered those area damaged which lay 10 to 20 cm above the highest flooded water level. saturated areas also become totally useless, life is limited here for a while, too. so, if we examine flooded and saturated areas together, an even higher proportion of the inhabited parts of the city is affected by the flood. visualizing the processed data on a map meant important new results, as it was the first time that we could assess the extent of flood on the basis of accurate figures (fig. 6-7). however, if we subtract the values of the assumed 0.5-1 meters thick infill layer from the data gained from the map analyses, it is even more clearly visible which parts of the city were affected by a high flood. this result also indicates that in climate cycles similar to the 18th and 19th centuries the extent of inundated areas might have been the same. it also became clear that before the foundation of the town, 86% of the measured points was certainly inundated when a higher flood occurred on this low-lying terrain, which was due to the absence of a thick, either natural or artificial infill layer (fig. 8). it means an almost total inundation actually. fig. 8 normal inundation extent of the points in database (i: inundated, s: saturated), as well as calculated with 50 cm infill (i50, s50) and 100 cm infill (i100, s100) the reliability of our method can be checked easily. we marked the elevation points on the inundation map of the 1879 flood, and they obviously indicated a total overlay with the inundation of the city which means that our results are correct (fig. 9). fig. 9 a) location of the studied points on an inundation map dating from 11 june 1879 (action plan, 1879); b) medieval city structure on an inundation map dating from 24 july 1879 (action plan, 1879) 10 szalontai (2016) since the primary purpose of our present study was to analyse the flood risk of the study area during a much longer time period, we must also emphasize that the highest flood was compared to the levels measured in 1879. in addition, we also found data that supports our hypothesis that the elevation of the original terrain was different centuries ago, or, for example, in archaeological times. unfortunately, we do not have precise and useful drilling data about it, but if we presume that a minimum of 50-cm-thick layer was formed at certain measuring points, we must be close to the truth. i. puskás measured a 50-cm-thick layer in the former fortress, which was formed before the 19th century, and there are other excavation proofs of 50 to 100 cm thick infill layers from other parts of the city, which layers originated in the middle ages or the modern era (puskás, 2008). we cannot find as thick an infill layer in an empty room inside of a fortress as in residential areas, there are no ruins of former buildings there, no sign of purposeful infill, and floods were not able to deposit a significant amount of mud due to the fortress walls. based on these observations and data, we are right to presume that there was a minimum of 50-cm-thick infill from the foundation of the city to the end of the 19th century. moreover, even higher values, up to a 100-cm-thick infill, are also likely to have occurred, but we must also emphasize that it still has to be researched in the near future. we cannot finish our investigation without commenting on the real destruction of the flood. the earliest measured data about the flood peak of the tisza in szeged originates in 1770 (buday, 1830). although there are older secondary sources describing the devastating effects of major floods, they do not contain any accurate data about flood peaks. for this reason, we do not know where the flood peak of the tisza was before the 18 th century. it is certain that the end of the 18 th century was characterized by a cooler and more humid climate both in european and hungarian history, which meant that river flow rates must have increased and resulted in higher floods. however, it also means that drier climate periods (e.g. the roman age, or the 10th to the 13th centuries) witnessed smaller floods, which also reduced the high flood risk of the city. as to settlement history, the most important issues concerning the tisza are related to the floods. the most important settlement historical issue of the frequently flooded areas was the population's ability to adapt to the changing stages and discharges of the river, to what extent they were able to use the excess water of the floods, or how they could mitigate flood damage (molnár, 2011). the tisza has two characteristics that distinguish it from other large rivers. one of them is that the river floods the low floodplain already at middle water level surface elevation, and its environment is gradually flooded. the other one is that the two annual flood cycles make life unbearable along the tisza due to the elongated time of river downflow and slow drying out of the flooded areas (fig. 10). it has been made even more difficult by the fact that the populated area of the city is of basin-like, and the slightly higher ridges along the river prevent the free flow of flood water from the deeper pools that are farther away from the river. so the whole process takes much longer than elsewhere. flood damage, isolation and all negative effects are extremely important in terms of settlement history, because they complicate life as well as land use (kiss, 2011). fig. 10 map of the catchment area of the river-system in and near szeged, and map of the permanent and temporary surface water cover before river engineering (szalontai, 2014b). green arrow: waterflow from the kiskunság sand ridge (homokhátság) without flood risk; red arrow: tisza floods posing significant flood risk and damages flood risk in szeged before river engineering works: a historical reconstruction 11 it cannot be accurately determined which areas were flooded in szeged and in its vicinity. we know about a flood that reached even the pool of fehértó from the west (in 1801), but floods usually inundated the areas that lie to the east of the highway leading to csongrád today. in the late middle ages, of all populated areas it was the northern part of the city, felsőváros (upper town) that experienced the most floods or was directly threatened by them. nevertheless, it was also common that alsóváros (lower town) was also flooded, for example in 1712 (reizner, 1899), when the flood arrived from the north and inundated the inhabited parts from that direction (fig. 11) fig. 11 length of inundations (number of days) (vágás 1991) from landscape assessment point of view it is also important to know where were dry surfaces where the inhabitants could move in case of a flood inundating the whole city. it is known that in 1689 and in april 1712 the whole city was inundated except for palánk due to the earth trenches. in these cases the surrounding vineyards and the “öthalom” hills were surely dry, which could be approached by boats (reizner, 1899; kardos, 1979). in 1770 szilléri hills, the highest situated small island (79.5-80 m) were also inundated, which meant that all other lower-lying areas were flooded for that time and the loess-covered “islands” were also inundated. engineering maps from 1830 demonstrate that these flooded areas extended to the öthalom hills and ballagitó areas; water covered low-lying arable lands, thus, the city was fully surrounded by tisza floods from the north. if we study the flood exposure of szeged, we have to take into account another important aspect. today we can state precisely where there used to be streams, pools in the populated parts of the city (szalontai, 2014a). these surface waters were not of temporary nature, but permanent, their riverbed was always visible and meaningful to the community, as long as it was not concealed (or destroyed) artificially. their long-lasting (sometimes persisting for centuries) presence is best proved by the fact that street and ground-plot structure was developed in harmony with the then-present subsurface water bodies, and thus the people living there adapted to their channels and water influx. but what is even more surprising is that not only the permanent hydrological elements trace out the possible settlement sites, but temporarily flooded areas as well. we can come to this conclusion also when we overlay the medieval town structure to the city map that was prepared five months after the great flood. in 1879, the deepest parts of the city were still covered by floodwater in july, after the march flood. these areas indicate those pools which were characterized by temporary inundation before the river was engineered. it can be noticed very well that these pools almost completely surround the earliest parts of the city, and they literally complement the blank spaces between the separated units. these urban wetlands were not built in with houses and remained empty until the 20th century. their single city structure utilization was the building of eugenius ditch after the turkish occupation as the southern end of the ditch was built by using these wetlands and pools as a security system. the stream that once ran along the northern wall of the former fortress had similar effects on the settlement structure, as there was a large wetland there that separated the two parts of the city for centuries, and this situation did not change over time, not even after losing the border fortification role it previously had. the low-lying areas were not inhabited, and they were usually swamplands with recurring inundation. the area is likely to have had aquatic or hydrophobic plants as the predominant vegetation. in the modern era, they were low-lying arable lands (so-called “nyomásföldek”) which served mainly for grazing. it is a complex water system, which received significant flood water supply on each occasion when the inhabited parts of the city were flooded. its pools are likely to have always been filled with water. due to the significant water supply of these pools, their infill or drying out became significantly difficult, which can also be considered as flood damage, similarly to the physical destruction caused by water. conclusion concluding the results of our study, we can say that, compared to the 19th century city, the inhabited parts of szeged were situated on lower-lying terrains for centuries or millenia before the foundation of the city. for this reason, particularly during periods of cooler and wetter climate, the tisza floods coming from the north inundated the entire area of the later city. the flood covered the low floodplain and the low-lying basins to be filled with water, thus creating an actual sea around the city with several kilometers of diameter. this huge amount of water made life as well as entering or leaving the settlement impossible. these conditions significantly limited the location of residential areas and therefore before the hungarian middle ages the center of settlement was found farther away from the banks of the tisza, and not along it, on the flood-free areas of the surroundings. the 10th and 11th centuries were characterized by a gradual warming, and the coming drier climate (medieval climate optimum) significantly improved this unfavorable hydrological feature, and must have reduced flood risk to a great extent (lamb, 1982; rácz, 2001). these changes led to the possibility of using the economic benefits of maros salt trade to start the development of the city, which finally turned szeged into one of hungary`s most important and flourishing cities. 12 szalontai (2016) references bertalan, a. 1884. szeged szab. kir. város földrajzi és meteorológiai viszonya. (geology and meteorology at szeged) szeged. 70 p. (in hungarian) blazovich, l. 2002. városok az alföldön a 14–16. században. dél-alföldi évszázadok 17. (cities of the great hungarian plain in the 14th-16th centuries) szeged. 271 p. (in hungarian) brázdil, r., kotyza, o. 1995. history of weather and climate in the czeh lands i (period 1000–1500). zürcher geograpische schriften 62, zürich. 260 p. farsang, a., puskás, i. 2009 a talajok sajátosságai a városi ökoszisztémában — szeged talajainak átfogó elemzése. (soil attributes in urban ecosystems – the detailed assessment of soils in szeged) földrajzi közlemények 133, 397–409. 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(szeged in the 14th century) tcsmt 14, 5–75. in hungarian mezősi, g. 1984. szeged környékének negyedkori és recens felszínfejlődésének néhány kérdése a részletes geomorfológiai elemzés tükrében. (quaternary and recent surface development int he vicinity of szeged based on a detailed geomorphological assessment) in: az alföld gazdaságföldrajzi kutatásának eredményei és további feladatai. ii. természeti környezet. békéscsaba 1984, 203–212. (in hungarian) molnár, s. 2011. environmental historical research of floodplain management demonstrated through two sampling sites on the great plain of hungary. phd theses, university of szeged, 125 p. nagy, m. 1957. szeged földrajzi energiái és a város hatásterülete. (geographical energies and the affected areas in szeged) a szegedi pedagógiai főiskola évkönyve, 137–170. (in hungarian) ozsváth, g. 2003. három, a közelmúltban visszakerült 19. századi kéziratos szeged térkép. (újabb malomadatokkal). (three maps recently became avaiable from the 19th century on szeged including new mill data). mkcsm 2002 (szeged 2003), 81–93. (in hungarian) puskás, i. 2008. urban soils:complex evaluation and classification of soils in szeged. phd theses, university of szeged, 153 p. rácz, l. 2001. magyarország éghajlattörténete az újkor idején (climate history of szeged in the modern age). juhász gyula felsőoktatási kiadó, szeged. 303 p. (in hungarian) reizner, j. 1899. szeged története i. (the history of szeged) szeged, 398 p. (in hungarian) rohr, ch. 2007. extreme naturereignisse im ostalpenraum. naturerfahrung im spätmittelalter and am beginn der neuzeit. köln-weimar-wien, böhlau verlag, 201–398. szalontai, cs. 2014a. the role and significance of the maty creek and the connected hydrological system in the settlement history of the vicinity of szeged. phd theses, university of szeged, doctoral school of earth sciences, geoarcheology, szeged, 131 p. szalontai, cs. 2014b. két víz között. hatalmi és stratégiai központ váltás szeged környékének településtörténetében. (between two floods. political and strategic centre changes int he settlement history of the vicinity of szeged). in: horváth, g. k. (ed.) vízhasználat, vízszabályozás és társadalom a 13–20. századi magyarországon. balassi kiadó, budapest, 37–78. (in hungarian) vágás, i. 1991. a tisza szabályozása. (river regulation works of the river tisza) in: gaál, e. (ed.) szeged története 3/1. 1849–1919, szeged, 133–139. (in hungarian) maps buday 1830. buday mihály város főmérnök által jegyzett térkép rajzolat melly sabad kir. szeged várossának belsőbb részeiben található motsáros víz állásoknak házhelyekre való felosztását mutattya. 1830. magyar nyelvű, színes kéziratos térkép. mérete: 950x600. méretarány: 2” bétsi hüvelk=100 öl. (ozsváth, 2003; szalontai, 2014) mfm jelzet nélkül. barilari et al. 1879. situation de la ville de szeged. szeged szab. kir. városának átnézeti vázlatrajza. másolva és kiegészítve a k. biztosság műszaki osztálya által. barilari, p. gros, l. jacquet, l. waldorp, j. kozlowski, th, szegeden 1879. évi július havában. magyar és francia nyelvű kőnyomatos árvízvédelmi térkép. méret: 78x122 cm. méretarány: 1:7200. mnl s068 v ny (részlet). heller 1880. szeged sz. kir. város földtani réteg-terve. a tisza 0 pontja alatt 4 méter mélységben képzelt vízszintes metszet. plan géologique de la ville de szeged. coupe horizontale prise au niveau duzéro fleuve de tisza. heller lajos mérnök térképe. 1:10000. 1880. sk td 329, td 381 (kuklay, 1880). kuklay 1879. szeged szab. kir. városának átnézeti vázlatrajza. a jelenlegi városi lejtmérési adatok. 1879. másolva és kiegészítve a k. biztosság műszaki osztálya által, szegeden 1879. évi július havában. endrényi lajos nyomdájából. mérték 1”=100 méret 33,5x42 cm. csml t102, sk td 319, tm 343, tm 73, tm 74. action plan 1879. június szeged szab. kir. város helyzetterve. a kir. biztosság műszaki osztálya által. mértékmérővel. sk td 323a action plan 1879. július szeged szab. kir. város helyzetterve.. a kir. biztosság műszaki osztálya által. mértékmérővel. sk td 322 abbreviations csml archives of csongrád county /csongrád megyei levéltár/, szeged mfm móra ferenc museum /móra ferenc múzeum/, szeged mnl national archives of hungary magyar/nemzeti levéltár/, budapest sk somogyi library/somogyi könyvtár/, szeged introduction study area data and methods methodology the detailed description of the applied historical maps results the topography of szeged flood risk of szeged conclusion references factors responsible for rural residential water supply shortage … journal of environmental geography journal of environmental geography 8 (3–4), 21–32. doi: 10.1515/jengeo-2015-0009 issn: 2060-467x factors responsible for rural residential water supply shortage in southeastern nigeria michael chukwuma obeta, cletus famous nwankwo* hydrology and water resources unit, department of geography, university of nigeria, nsukka *corresponding author, e-mail: famouscletus@yahoo.com research article, received 12 october 2015, accepted 27 november 2015 abstract efficient water supply is very crucial to sustenance of socio-economic growth, poverty attenuation, and food security. in most rural areas of developing countries including nigeria water supplies are not commensurate with demand leading to a shortfall in water use and many people suffer from this scenario. this research investigated the factors responsible for rural residential water supply shortage in southeastern nigeria. data were collected through the use of four mixed but complimentary methods namely questionnaire survey, interviews, focus group discussions and secondary data sources. the data generated were analyzed through the use of descriptive and inferential statistical tools. principal component analysis was employed to combine the variables accounting for water supply shortage into a few underlying dimensions. the results indicated that physical environment and inadequate water supply infrastructure; socio-economic and geographical location; management and socio-cultural problems are responsible for water supply shortage in the area. residential water supply can be sustainable in the area by regulating the influence of these factors impacting on water supply as well as lessen the implications of water deficiency. the research concludes that the process of water supply development should be stepwise in accordance with the participatory and managerial capacity of communities. keywords: water supply constraints, sustainability, service delivery, community participation introduction clean, safe drinking water is scarce. matter (1984) have recognized that water supply has been a primary logistical challenge since the beginning of civilization and balancing water demand and supply has been a major concern of all human society of all times. the objective of water supply is the provision of potable water on a constant basis which addresses security of supply across seasons, and between wet and dry years, and is also imperative if health and wider poverty mitigation benefits are to be met and sustained (getis et al., 2008; nwankwoala, 2011; obeta and chukwu, 2013). worldwide, 663 million people lack access to safe water although there is regional variation. the populations without access to safe drinking water are mainly in sub-sahara africa and asia accounting for 84.33% of total. of the 663 million people, 319 million people (51.88%) are in sub-saharan africa while 260 million people (39.22%) are in asia (who/unicef jmp, 2015; usbc, 2015). sub-sahara africa has the largest population without access to safe water. millions of people in rural communities and poor urban centers throughout this region suffer from lack of clean, safe water (the water project, 2015). safe drinking water provision in rural areas of africa and asia is a major challenge. rural water supply is stalled by poor coordination, poor maintenance culture, poor technical institutional structure, multiple programs, lack of data for planning, overbearing bureaucratic control by various supervising ministries, lack of professional inputs in projects, lack of community participation, inadequate funding, irregular disbursements of subventions, inappropriate infrastructure as well as lack of clear policy direction, lack of focus in terms of goals and objectives which resulted in the country’s inability to achieve full coverage of the rural population with safe water supply (katz and sara 1997; ajayi et al., 2003; offodile, 2003; oteze, 2006; oyebande, 2006; lockwood and smits, 2011). in africa, it is not easy to set up institutional arrangements that will ensure that drinking water facilities are provided, maintained, and managed in a well-organized, fair, and sustainable way (bakalian and wakeman, 2009; sun et al., 2010). providing safe drinking water in rural areas are mired by both market and government failures. the lack of incentives often shelve the private sector to invest in rural water supplies due to the high costs of infrastructure development and the high transaction costs of collecting fees for drinking water in such areas, especially if the awareness of the value of safe drinking water is limited and if people can easily opt for other water sources (sun et al., 2010). ensuring that government staff has sufficient funds and incentives to manage rural water facilities in a sustainable way are main challenges when government provide safe drinking water (sun et al., 2010). to address these market and government failures, community-based ap22 obeta and nwankwo (2015) proaches have been widely adopted yet, it is well-known that communities may also fall short of providing services effectively due to problems such as elite capture and limited capacity (katz and sara, 1997; sun et al., 2010; lockwood and smits, 2011). a fundamental shift from centralized ownership of water supply systems to local ownership and control has been experienced over the past decades (harvey and reed, 2003). along with the shift comes a deviation from “supply-driven approaches” to demand based approaches”. the transition follows the market place economics principles: people pay for the upkeep of valued items while unvalued commodities are not paid for. water systems deteriorate because they are installed in communities that do not value them. katz and sara (1997) analyzed the performance of water supply systems in six countries (benin, bolivia, honduras, indonesia, pakistan and uganda) and found that community participation significantly increased sustainability of water supply project. however, despite the widespread application of community management of rural water supplies in subsaharan africa, the sustainability of such programs remains unsatisfactory (harvey and reed, 2007). dewilde et al (2008) opined that the deep reliability of water systems and the capacity of communities to maintain and manage the systems need to be evaluated before you can make judgment on the effectiveness of safe water programs. analyzing the economic community of west african states (ecowas), olokesusi (1990) noted that water supply situation in this region is unsatisfactory. the reasons for this have been the growing population and the water engineers’ shortfall in terms of scaling water projects in conformance with purpose. most often water projects in this region are build beyond the capacity of the engineers to manage and maintain. although the millennium development goals (mgds) target of reducing by half the population not having access to safe water supply have been achieved, figures are still high in nigeria especially in rural areas (who/unicef jmp, 2015). policies to improve water supply in the country have been recommended. for instance, obeta (2013) suggested that institutional reform, network rehabilitation, improved tariff, support by local government authorities, human resource development, use of simple technology, setting up a rural development commission among other things are key actions to improve the water supply in rural areas. nwankwoala (2011) emphasize the need to practice traditional approaches to water supply, the breakdown of sector boundaries and a search for new practical solutions. uwazie et al. (2009) called on government to decentralize ownership and management of water supply systems to involve optimal community participation and support from the private sector. onyenechere (2009) indicated that the participation of the private sector in water provision is necessary but needs strong regulations for public protection. however, the implementation of recommended policies has been problematic. the reasons for this have been largely due to lack of political will and misappropriation of fund (adewuyi, 2013). despite the many agencies and programs for water supply in nigeria, nigerians still lack access to adequate water supply. in southeastern nigeria for instance, 80% of people in rural communities lack adequate access to potable water supply, they still depend on unprotected sources. the people trek long distances to fetch small quantity of water from the streams and springs (national bureau of statistics, 2008). based on the foregoing, it is important to investigate the reasons why access to safe water supply remains inadequate in southeastern nigeria. this paper, based on principal research in six rural communities in awgu local government area (alga) of enugu state, nigeria will attempt to access the nature of water demand and supply in the domestic sector, ascertain whether water demand is satisfied by supply, identify the factors responsible for water shortage and search for possible alternatives to the current water supply strategies. study area this study was carried out in awgu local government area of enugu state, southeastern nigeria. geographically, the area is located between latitudes 06o 00’ and 06o 19’ north of the equator and longitudes 07o 23’ and 07o35’ east of the greenwich meridian (fig. 1). the area is bounded in the north by udi and nkanu west local government areas, in the west by oji river local government area and share boarder with isochi local government area of abia state in the south. currently, awgu local government area is composed of 20 autonomous communities, namely, agbogugu, agbudu, amoli, awgu, awgunta, ezere, ihe, isu-awaa, ituku, mbgidi, mgbowo, mmaku, nenwenta, nkwe, obeagu, ogbaku, ogugu, owelli, ugbo and ugwueme (enugu state government, 2014). awgu local government area derived its name from awgu town one of these autonomous communities which also serves as the headquarters. awgu is a town in awgu local government area. the climate of the study area falls under the tropical wet and dry climate ‘aw’ of koppen climatic classification scheme (anyadike, 2002; lutgens and tarbuck, 2004; getis et al 2008; mozie, 2011). the atmospheric condition of the study area depends on the position of the overhead sun and the inter tropical discontinuity (itd) (anyadike, 2002). the average daily minimum and maximum temperature of the area are about 23.3o c and 27o c respectively while its average monthly maximum temperature is about 31.5o c (anyadike, 2002). rainfall in alga is very high and intense. the average monthly rainfall ranges from 250mm in april to 380mm in october, with a mean annual total of 1500mm (anyadike, 2002). the geology of the area is marked by coal, shale and sandstone. the shale is bluish, grey, and well-bedded and is occasionally intercalated with calcareous sandstones and limestone (ofomata, 2002). also, fine to coarse grained, massive sandstone, locally cross-bedded with some pebble beds and subordinate bands of siltstone and carbonaceous shale are present. the awgu formation is the youngest of the folded sequence in south-eastern factors responsible for rural residential water supply shortage … 23 nigeria (ofomata, 2002). the area is also marked by long, broken hills especially in the western flank and lowland in the eastern side. these hills have steep slopes and could attain an altitude of about 350-400 meters above sea level with mean slope angle of 15o and a modal class of 11o (mozie, 2011). the study area is drained mainly by numerous finger-like springs and streams. most of these streams are seasonal. they dry up during the dry season (novembermarch) and discharge large volume of water in the wet season. most of the streams have their source from top of the hills and flow downhill. the vegetation of the area varies with topography. natural vegetation is denser at the valley and sparse at the top of the hills. phil-eze (2005) observed that graminoids cover the top of the hills while trees are dominant in the valley. the top and slope face of the hills are more covered by grasses such as andropogon gayanus, ctenium spp, hyparrhenia barteri etc (ofomata, 1997). the common tree species found are isoberlina doka, anona senegalensis etc. (national resources conservation council, 1992). awgu local government area has a population of 198, 134 people as at 2006. out this, 95, 421 are males while 102, 713 are females (federal government of nigeria fgn, 2009). the distribution of population is uneven; a few areas are densely populated while many others areas are virtually uninhabitable. majority of the population settle at the foot of the hills because of the difficulty posed by the rugged terrain and because the lowland have fertile soil that support high crop yield. the settlement pattern on the hills is clustered with a nearest neighbor index of 0.82 while settlement pattern on the lowland area is dispersed with a nearest neighbor index of 1.72 (mozie, 2011). methods six of the 20 autonomous communities in alga were randomly selected for this study namely agbogugu, awgu, mgbidi, mgbowo, mmaku and ugwueme (fig. 1). a combination of instruments for data collection including questionnaire survey, field observation, key informant interviews and focus group discussions was used to generate data for this research. questionnaire survey a total of 300 questionnaires, 50 questionnaires in each of the six sampled communities were randomly distributed to households to acquire data on the factors affecting water supply in the area. trained research assistances administered the questionnaires. the respondents (head of households) were asked to identify the factors that are fig. 1 location of the study area and the investigated autonomous communities: 1: agbogugu, 2: awgu, 3: mgbidi, 4: mgbowo, 5: mmaku, 6: ugwueme 24 obeta and nwankwo (2015) responsible for water supply shortage in the study area. of 300 questionnaires that were administered, we recovered 290 (96.67%). the indicators were predefined as shown in table 1. the main question was “which of these factors affect water supply in your community”? data on quantity of water demanded and supplied were obtained through household water budgeting using daily water need and water use based on household sizes. table 1 water supply shortage indictors factors label rapid population growth rpg seasonality of water sources sws absence of water infrastructure abwi long distance to stream/spring water sources ldssws non-protection of stream/spring water sources npssws inadequate community participation icp lack of political will lpw politicizing water project pwp limited financial capacity lfc aging water infrastructure agwi misappropriation of water supply projects funds mwspf topographic constraints tc poor maintenance of water supply facilities pmwsf tradition and culture tnc urbanization urb vandalism and damage of water facilities vdwf geographical location gl absence or inadequate water storage facilities aiwsf geological factor gf ownership of water supply facilities owsf key informant (stakeholders) interview interview as a tool of data collection is very important. this is because it allows us to interact with the people allowing them to express their thoughts about the water problems they are facing (timmer et al., 2007). the following stakeholders were interviewed; traditional rulers (igwes), the water department officials, community representatives, women leaders and youth leaders. a total of seven (7) interviews sections were done. in each of the six communities, one interview sections was held. those interviewed were the traditional rulers, ward councillors, community representatives, women leaders and youth leaders. meanwhile, another interview section was held at the local government secretariat. those interviewed are the water department officials and enugu state rural supply and sanitation agency (enruwasa) officials. the information gathered from these interviews was used to comprehend and confirm the responses from the questionnaires for better understanding of the problems. focus group discussions (fgds) focus group discussion (fgd) is a good way to gather people from the same background or experience to talk about a particular topic of concern (nzeadibe and ajaero, 2010). a focus group allow participants to talk to one another and build on one other’s comments rather than continually responding directly to the moderator unlike interview (krueger and casey, 2002). focus group discussions (fgds) was conducted in each of the six randomly selected communities in the study area. the participants included the stakeholders and head of households. the research participants for the fdgs participated voluntarily and comprised between 6 10 participants in each community. the views expressed by the fgds participants are incorporated into the findings of this research. analysis of data collected the analysis of the factors responsible for water supply shortage in the study area was first done using descriptive statistics (frequency and percentage). principal component analysis (pca) of statistical packages for social sciences (spss) program version 20.0 was used to combine these factors affecting water supply into a few underlying dimensions. pca is statistical procedure that uses an orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of lineally uncorrelated variables called principal components (anyadike, 2009; vialle et al., 2011; orakwe and chukwuma, 2015). pca combines large number of indicators into fewer, more analogous groups, each group defining the underlying dimension in the contributing variables forming the group (anyadike, 2009). to do this, it is essential to estimate the number of significant factors present in the data. specifically, a matrix of pair-wise correlations among indicators is collapsed into eigenvectors, which, in turn, are sorted in descending order of their corresponding eigenvalues (vialle et al., 2011). the analysis is based on the correlation matrix, which is the covariance matrix of the synchronized indicators, to eliminate the scaling effect. the indicators have been computed as the sums of squares of deviations divided by n-1 (where n is the valid number of cases). significant principal factors (pcs) with eigenvalues greater than unity (i.e., pcs explaining more than the variance of one indicator) were extracted (orakwe and chukwuma, 2015). orthogonal rotation using variance maximisation varimax was used to maximise the variance of the squared component loadings for each component, repartitioning the loadings towards higher components, thus improving interpretation (anyadike, 2009). the basic calculations were adequately and speedily done using the spss program as suggested by anyadike (2009). the responses were coded as 1= identified and 0 = not identified. the number of observation was n = 290 for all indicators. for example, abwi was identified 189 times in 290 observations hence the column for abwi in the spss data entry window will have 189 “1s” and 101 factors responsible for rural residential water supply shortage … 25 “0s”. the 0s will fill up the remaining rows after the 1s to sum to 290 observations. significant component loadings are considered from an arbitrary threshold of 0.70, based on the size of the component loadings. results characteristics of respondents 95% of the respondents are male while 5% are female.1.4% of the respondents are between the ages 20 and 29, 2.4% are between 30 and 39 years, 58.9% are between 40 and 49 years, 12.8% 70 and 79 years and 0.69% are older than 80 years. 2.41% of the respondents have no education, 6.2% have primary school education, 65.5% have secondary school education, and 25.9% have post secondary education. of this 25.9% of the total, 5.5% have national certificate of education (nce), 7.24% have national diploma (nd), 12.1% have bachelor’s degree/higher national diploma (hnd), 0.69% has master’s degree and 0.34% has phd. 67% of the respondents are farmers, 12% are artisans, 8% work in the civil service, 9% are traders and 4% has other occupation. assessment of water demand and supply in the study area from our findings water supply is not commensurate with demand in alga. on average a gap of 28.52% of water demand is not satisfied by supply in the study area. the gap in quantity of residential water demand and supply is presented in table 2. according to table 2 the quantity of water demanded l/person/day is greater than the quantity of water supplied. although water demand is low (48.85 liters) on average, it is not satisfied by supply (34.54 liters). the quantity of water consumed by an individual in the study area is very small and indicates inadequate access to water supply. the gap between demand and supply is not the same for all communities sampled. mgbidi recorded the highest water shortage followed by mmaku because movement in these two communities is difficult such that people find it difficult to access the various sources of water. mgbowo however, has the least water shortage because the people depend mainly on wells that are very accessible. also as shown in table 2, there is water supply shortage in all the sampled communities. a total of 71.48% of water demand was satisfied by supply leading to a gap of 28.52% in the study area. descriptive analysis of contributing factors table 3 summarizes the various indicators and the frequency of how the respondents perceive them as factor affecting water supply in the study area. these indicators have been classified into three groups based on the percentage of respondents that identified them as influential. from 50% and above are classified as most important, 49% 25% as important and less than 25% as less important. table 3 shows the percentage contribution of the six communities studied to the factors responsible for water supply deficiency in the study area. the three groups of indicators are discussed as follows. most important factors absence of water infrastructure is the most important factor affecting water supply in study area. 65.17% of respondents attest to this. in all the sampled communities, water supply infrastructures are lacking. although some communities such as awgu, ugwueme and mgbowo have mini water supply system none of them are functional as at the time of this research. awgu water scheme was constructed about six decades ago but it has not been functioning regularly since nigeria’s independence in 1960. the ugwueme water scheme is as well not functional just two months after it was completed. also, mgbowo water scheme which is the largest water scheme in the study area has not been commissioned since 2003 when its construction started. other communities lack water scheme but some communities such as mgbowo, mgbidi and mmaku have been provided with boreholes although these boreholes are plagued by constant breakdown and some of them yield water of poor quality. the irregularity of the water schemes and boreholes is attributed to absence of personnel with the technical skill to maintain them in the area. in the rainy season, rainfall is present and stream discharge is high while in the dry season, the opposite is the case. the consequence of this is that the people are short of water in the dry season and have more supply in the wet season. sws is considered by the people as the one most important factor responsible for water shortage in the study area. 61.72% of the respondents attested to this condition. in severe conditions water shortage in dry seasons could pose great danger. for example, in ethiopia, access to safe water in drought is always a major problem, and water-related disease resulting from retable 2 gap between daily household water demand and supply in the study area sampled communities no. of sampled households average size of household n=290 water demand l/day/person water supply l/day/person gap between demand and supply l/day/person % of water demand satisfied by supply /day/person awgu 49 7 39.14 27.59 11.55 70.49 mgbowo 48 6 45.89 40.21 5.68 87.62 agbogugu 46 7 41.06 27.16 13.90 66.15 ugwueme 49 6 47.04 37.86 9.18 80.48 mgbidi 49 6 63.09 39.05 24.04 61.89 mmaku 49 6 56.85 35.37 21.48 62.22 mean 6 48.85 34.54 14.31 71.48 26 obeta and nwankwo (2015) stricted water availability and access often causes fatalities (coulter et al., 2010). awgu local government area groundwater resources have not drained even though boreholes are being sunk by enruwasa in partnership with the united nations children’s fund (unicef) in some communities. in three communities (mgbowo, agbogugu and awgu) the people reported that the borehole water is not suitable for drinking because of its salty taste and odor. the awgu local government area water department officials stated that the poor quality of the unicef-assisted borehole water is due to the geology of the area. 59.65% of the respondents confirmed this situation. it was reported also that several attempts to sink boreholes in some villages was not successful due the underlying rocks (coal) that prevented them from reaching the water table. a comprehensive study of the geology of the area will reveal places to be explored for water and also help in data gathering (fagoyinbo, 2015). the variation in groundwater quality in geologically complex area is caused by variation in mineralogy and rock chemistry (fagoyinbo, 2015). in addition, water well yield and groundwater quality are determined by an intricate interplay between fractures in the aquifer, the local soils and saprolite which provide storage and recharge to the bedrock fractures (toth, 1993). government efforts to supply water to the villages have yielded no laudable result. although water schemes are provided, none of them is currently functional. they are poorly maintained. 58.96% of the respondents attested to this state of affairs. water storage facilities are inadequate in the study area. 58.27%of the respondents agreed that the absence of storage facilities contributes to water supply shortage in the area. the tanks that were provided by the colonial masters are no longer in used. these tanks are connected to springs such as the ngeneofia in mmaku, nkwo in awgu but most of them are no longer available. storage facilities are indispensable to store up water to be used in the dry season particularly in countries that experience protracted period of drought. fao (2012) indicated that the level of infrastructure development that controls storage is one of the three main dimensions that typify water scarcity. non protection of stream/spring water sources have left most water sources polluted. 51.38% of the respondents confirmed this. many streams are polluted by villagers who bathe inside the streams, wash their cloths and farm produce as well as defecating along and beside the streams channel which are washed into the stream by runoff rendering the stream water not safe for drinking. open defecation is highly practiced in the area and this is one of the major pollutant of surface water bodies. fao (2012) noted that protection and efficient management of freshwater resources (streams, rivers, lakes, and springs) would guarantee their long-term sustainability thus water supply sustainability. to achieve this, who (2006) and us epa (2008) noted that stakeholders should be engaged in formulating and implementing source water protection policy. majority of the people in the study area are poor and economically weak. they have low adaptive capacitable 3 respondents identified factors affecting water supply in the study area percentage of households that perceived the factors as problem (%) indicator label nr of households that perceived the factors as problem (n=290) a w g u m g b o w o a g b o g u g u u g w u e m e m g b id i m m a k u t o ta l most important abwi 189 12.41 6.55 16.20 14.14 7.59 8.28 65.17 sws 179 12.41 13.79 18.97 4.14 5.17 7.24 61.72 gf 173 12.41 14.48 12.07 6.20 6.89 7.59 59.65 lgw 171 7.59 7.24 12.07 14.48 8.28 9.31 58.96 aiwsf 169 7.24 11.38 14.83 10.00 7.93 6.89 58.27 npssws 149 10.00 9.31 12.07 5.86 7.59 6.55 51.38 lfc 148 6.55 6.89 9.31 12.41 8.28 7.59 51.03 important ldssws 140 10.69 9.66 7.93 4.48 5.86 9.66 48.28 rpg 139 11.72 8.97 9.66 5.17 6.20 6.20 47.92 tc 132 7.93 1.38 0.51 14.14 11.38 10.00 45.34 icp 127 6.89 6.20 10.34 9.66 5.17 5.52 43.78 gl 123 9.66 8.96 10.00 3.45 4.83 5.52 42.42 agwi 111 7.24 7.59 4.83 5.86 6.20 6.55 38.27 pwp 98 7.24 6.55 5.52 5.86 4.14 4.48 33.79 owsf 96 6.20 8.62 3.10 7.93 3.45 3.79 33.09 pmwsf 85 7.24 4.48 4.14 3.45 3.79 6.20 29.30 less important mwspf 72 5.86 3.79 4.14 5.17 2.76 3.10 24.82 vdwf 66 8.28 4.48 1.72 1.72 3.10 2.76 22.06 tnc 61 1.72 5.17 5.86 2.41 2.76 3.10 21.02 urb 54 6.55 3.10 5.86 0.34 0.51 1.03 17.39 factors responsible for rural residential water supply shortage … 27 ty to cope with water supply shortage consequences. they are also unable to participate in the water projects constructed in the area as a result of their low economic base thereby denying them the ownership of these projects. the people are also unable to buy vended water and self supply is practically limited because it is capital intensive. 51.03% of the respondents confirmed this situation. financial instability causes a major setback to water development in developing countries (fao, 2012). the national bureau of statistics (nbs, 2008) indicated that about 80% of southeastern nigeria rural population is poor as against 20% rich people. this means that most of the people may not be able to pay for water supply services. important factors streams and springs are far from majority of the households. most often they have to climb hills to fetch water from the springs. the long distance to these water sources makes it difficult for the villagers to fetch the quantity of water needed for their domestic activities. 48.28% of the respondents attested to this situation. uwazie et al. (2009) remarked that reducing the distance to water supply source in rural areas will reduce the stress of women and children who can now devote more time to income generation and education, and will improve the health of community members being ravaged by water related diseases. for decades even before the colonial period, people in the study area depend on springs and stream and till date, they still depend largely on these traditional sources of water. however, while population is growing rapidly, these sources are not increasing. as a result, the proportion of people depending on each spring and stream has increased by more than ten times. consequently, there is pressure on these limited water resources and the resultant effect is water scarcity. the disproportionate level of population growth and water supply can be balanced if the available water projects and facilities in various communities in the study area are made functional and population growth checked. 47.29% of the respondents confirmed this situation. similar situation abound in many parts of the world. getis et al. (2008) observed that water is essential for development but its demand frequently exceeds supply in many parts of the world especially as population rapidly increases. as a result, regions with high population growth rate are expected to have water supply shortage if proper measures are not taken to equal demand and supply. for example, glass (2010) noted that the water crisis in yemen is caused by high population growth and exhaustion of water. the situation is severe and may cause mass fatalities due to dehydration of its people unless immediate action is taken. the rugged terrain that occupies the study area’s landscape hinders not just water development but other aspect of development. the topography of the study area hinders the distribution of water via pipe. in ugwueme for example, the water scheme that was developed by the anambra-imo river basin development authority was not successful in terms of distribution of water to villages because of the rugged nature of the area. topography is a major challenge if large scale water scheme is developed to supply water to many communities in awgu local government area because piping will be difficult and expensive. 45.34% of the respondents confirmed this condition. in line with this, bakalian and jagannathan (1991) noted that the installation of conventional water infrastructure in complex topographic conditions is very costly. furthermore, the study area is located where climatic condition does not favor water supply for all the months of the year. in the wet months (april-september) water is available in springs, wells and streams. also, harvested rain water serves some purpose such washing, cleaning, bathing etc. however, in the dry months (october-march), streams are dry, springs become fingerlike, some wells yield small quantity of water and there is no rain water to harvest. 42.42% of the respondents attested to this situation. this situation is typical of the tropical wet and dry climate of the humid tropics (wohl et al., 2012). the level of community participation in water provision is low in the study area and has led to the abandonment of water facilities and projects. 43.78% of the respondents confirm this. the absence of water committee to manage the projects after they have been constructed has left most the water project dysfunctional. similar scenario was discovered in benin republic, bolivia, honduras, indonesia, pakistan and uganda (katz and sara, 1997). also, because there is no regulation on the use of stream water which is supposed to be coordinated by village water committee to ensure the proper use of water e.g. preventing stream pollution by placing sanctions on washing, bathing inside the streams and defecating along the stream channel has left most of the streams polluted all seasons limiting available water especially to people living at the lower course of the streams. in addition, some water projects in the area are initiated no attention to the physical environment parameters of the area before sitting the projects. this is particularly so for the newly installed public boreholes. water is a very pressing need of the people and can be used for political goals. however, the reverse has always been the case. 33.79% of the respondents attested to this situation. in developing countries especially in africa, (briscoe, 1999; ünver et al., 2012) acknowledged politicizing of water projects as reflected in where to site the project. water projects are sited based on political affiliations of community leaders. the study area has some water facilities that are provided by the federal and state government however, most of these facilities are aging. they have been neglected by both the facilities providers and the local authorities while others under construction have been abandoned. similar situation is obtainable in other developing regions (wwc, 2015). the problem of ownership of the water projects has led to the neglect of some water supply facilities. 33.09% of the respondents confirmed this. most of the public boreholes are installed by state government in partnership with unicef while some are installed by the federal government. the federal government boreholes are beset with incessant break28 obeta and nwankwo (2015) down. when they stop functioning, it takes about 1-2 years before they are repaired depending on the administration’s priorities. the situation is such that some federal government’s water facilities are not maintained by the state government. for instance, the water supply schemes in ugwueme and mgbowo are provided by the federal government and because their ownership has not been transferred to the state government, they are abandoned. as a result of the irregular maintenance of the facilities provided by the federal government, communities that have only federal water facilities such as ugwueme are greatly affected. 29.30% of the respondents attested to this state of affair. as noted by (fao, 2012; wwc, 2015) poor maintenance of water infrastructure is a growing concern for water supply sustainability in developing countries. less important factors misappropriation of water supply project funds might occurred according to the opinion of 24.82% of the respondents, however, there is no clear evidence to uphold this claim. moreover, as fao (2012) noted, a lack of transparency and poor accountability breeds fraud and are reasons for poor performance, resistance to change and unbalanced delivery of water services. vandalism is a problem that beset water facilities in the area. for instance, in umuhu village, awgu autonomous community, the absence of village water guards gave room for some youths to vandalize the pipe connecting the ogbuma stream and the awgu water supply scheme. they also extort money from villagers who come to fetch water from the stream. 22.06% of the respondents attest to this. this situation reflects the findings by water and sanitation for the urban poor (wsup), a non-profit organization based in zambia and nkana water and sewerage company (nwsc) in zambia in 2014 which indicated that water and sanitation utilities often experience vandalism and theft of their property. the study showed that the acts of vandalism take a number of forms: they include water theft leading directly to a loss of revenue for the utility, and the vandalism and theft of valuable metal pipes, fittings and manhole covers leading to an increase in the utility’s maintenance costs (wsup and nwsc, 2014). tradition and cultural factors does not have much influence on water supply shortage in the area but it has helped some villages to protect their drinking water sources. for instance, in awgu autonomous community, there is a tradition that the fishes in ogbuma stream is not to be harvested and no any form of activity is allowed in the upper course of the stream. this tradition has helped preserved and protected the stream for centuries. ogbuma stream is still the most relied source of water in the community. another example is the oviangu spring. as the tradition states, “there is no tourist activity in the vicinity of the spring” to avoid contamination. in communities such as agbogugu where such tradition does not exist, their streams and springs are often polluted. 21.02% of the respondents attested to this. from an african perspective, water is of social, cultural, spiritual and economic importance (zenani and mistri, 2005). against this background, mathew and le quesne (2009) indicated aligning culture and tradition with institutional and legal water management strategies could solve water problems better in rural areas. in many rural settings in africa, access, use and management of resources e.g. water is generally informed by customary rules that form part of a complex system of traditional governance (kapfudzaruwa and sowman, 2009). finally, urbanization has the least percentage (17.39%) of the respondents attesting to it. the influence of the factor in the study area is felt mostly in awgu and agbogugu autonomous communities where there is gradually urbanization. the result is that some households are now far from major springs and streams; they have to take very long distance to these water sources fetching small quantity of water because earliest settlements are found in areas close to streams in the eastern communities and areas close to springs in the western communities of the study area. urbanization can put unparalleled pressure on a renewable but finite resource, principally water (fao, 2012). pca analysis of the contributing factors from our analysis, we have been able to identify three unique factors which can be used to explain the causes of water scarcity in the study area. thus, we have successfully transformed our 20 predictor variables to 3 underlying dimensions (table 4), which, in order of importance are as stated below: 1. physical environment and inadequate water supply infrastructure 2. socio-economic and geographical location 3. management and socio-cultural problems physical environment and inadequate water supply infrastructure with an eigen value of 6.519 and 32.597% of variance explained, the first component loads heavily on sws (seasonality of water sources), gf (geologic factor), lgw (lack of government will), aiwsf (absence/inadequate water storage facilities), and abwi (absence of water infrastructure). there is positive relationship between this component and the variables. it is described as the effect of physical environment condition and inadequate water supply infrastructure. the study area is in a location that the geology has not favored water supply development. the area is underlain by coal, limestone, clay and shale which have made borehole sinking quite difficult. the boreholes sunk in areas underlain by coal do not yield water and those in limestone areas yield water of poor quality. in addition, the area is located where there is two marked climatic seasons. springs and stream yield more water in the wet season than dry season. furthermore, the water supply systems and some of the unicef assisted boreholes are not effective in supplying water to the people. this is as result of lack of will by government to provide and maintain water supply and storage facilities. factors responsible for rural residential water supply shortage … 29 table 4 rotated component matrix from the spss rotated component matrixa investigated variables component 1 2 3 abwi *0.883 0.232 0.194 sws *0.910 0.280 0.206 gf *0.904 0.325 0.212 lgw *0.895 0.345 0.214 aiwsf *0.879 0.368 0.217 npssws 0.670 0.637 0.244 lfc 0.659 0.649 0.246 ldssws 0.568 *0.734 0.274 rpg 0.557 *0.742 0.279 tc 0.483 *0.779 0.321 icp 0.435 *0.790 0.358 gl 0.401 *0.786 0.392 agwi 0.318 *0.732 0.509 pwp 0.248 0.635 0.647 owsf 0.241 0.615 0.667 pmwsf 0.217 0.484 *0.773 mwspf 0.204 0.314 *0.885 vdwf 0.200 0.241 *0.919 tnc 0.195 0.194 *0.925 urb 0.186 0.152 *0.897 eigen value 6.519 6.025 5.886 % variance 32.597 30.127 29.429 cumulative % 32.597 62.724 92.153 extraction method: principal component analysis. rotation method: varimax with kaiser normalization. a. rotation converged in 5 iterations. socio-economic and geographical location this second component has an eigen value of 6.025 and explains 30.127% of the total variance. it loads heavily on icp (inadequate community participation), gl (geographical location), tc (topography constraints), rpg (rapid population growth), ldssws (long distance to stream/spring water supply source) and agwi (aging water infrastructure). all the variables show that there is positive relationship between the variables and the component. generally, this component describes the problems caused by socio-economic and physical barriers in the study area. this is because majority of the people in the study area are poor coupled with rapid population growth that further push the dependency level higher leading to more socio-economic weakness (increase in poverty level). the teeming population becomes burden to the individual household, the community as a whole as well as the government such that investment in water infrastructure is limited due to high dependency rate on head of households which limit households’ capacity to participate in water supply development. also, the rugged nature of the area’s landscape makes it difficult for water distribution through pipes because of the numerous jointed hills that will obstruct the laying of pipes. this component is therefore, described as the effect of socio-economic and physical barriers. management and socio-cultural problems the third component has an eigen value of 5.886 and explains 29.429% of variance. it loads heavily on vdwf (vandalism and damage of water facilities), tnc (tradition and culture), urb (urbanization), and mwspf (misappropriation of water supply project funds). this factor is difficult to interpret but it could be described as management and socio-cultural problems. this is because proper management of water facilities is lacking in the area. vandalism of water facilities could have been prevented if the water department of the local government employs guards to secure water facilities and ensure that damaged facilities are repaired or replaced by judiciously appropriating water funds. the level of education of a society reflect the social status the society accords, their level of thinking and to some extent their economic capability. the level of education in the study area is low with associated poverty of the mind which manifest as vandalism of government property (water facilities) by unemployed youths owing to their thinking that government has not done enough to elevate them from abject penury. in addition, communities that their tradition and culture does not provide for water protection have most of their water sources polluted. furthermore, urbanization will increase the demand for water because there will be other demanding sectors such as industrial and commercial sector. also as more buildings are erected, recreation centers built and other social amenities put in place, the natural hydrological system will be altered. urbanization affects hydrological components such as precipitation, evaporation, infiltration, evapotranspiration (ezenwaji, 2012; obeta, 2013). currently, this factor has less influence on water supply in the area but could be a major problem in the future. discussion efficient water supply is very vital to achieving sustainable development in the area because water supply has link with rural livelihood system (houweling et al., 2012). the shortage in water supply could have both direct and indirect impact in the area. water supply shortage can affect directly some domestic activities such as bathing cooking, washing, basic sanitation and waste disposal. insufficient water for these activities can result to poor hygiene which spreads water-related diseases such as diarrhoea, cholera, malaria, dysentery etc. (basu et al., 2015). consequently, households will have huge part of their income spent on health care leaving them with insufficient money for education, nutrition, better shelter etc. (pearson et al., 2015). 30 obeta and nwankwo (2015) water supply shortage could also hinder economic progress of the area. poverty reduction is linked to water development especially as the economy of the area is greatly dependent on agriculture. agriculture is the primary prospect for rural economic growth and development and water is very vital to this. adequate access to water supply can help lift many rural households out of poverty because water is crucial to large scale agriculture especially in dry seasons, crops and animals need water for their growth (crow et al., 2012). insufficient water for agriculture could arrest the food security of the area leading to poor nutrition. poor nutrition could weaken the people that they die from illnesses and infections that are not usually severe (lenton and muller, 2012). generally, the main water supply problems in the study area are related to physical environmental barriers and anthropocentric factors. the physical barriers are geology, climate and relief while the anthropocentric factors are water infrastructure deficit, lack of community participation, population pressure, financial constraints, politics, vandalism, poor maintenance culture, urbanization, tradition and cultural factors. based on our analysis of the factors responsible for water supply shortage in the study area, the following recommendations are made in the following paragraphs. public awareness campaigns have been recognized as effective sensitization program in water management (butler and memon, 2006; willis et al., 2011). rural people need to be informed that water is very important to their development and they should try to preserve and conserve the water resources they have to avoid further scarcity. the incessant pollution of streams and springs through washing of cloths, bathing and defecation in the stream could be attributed to lack of awareness of the consequences of such activities. awareness can be done through the use of community town criers, cultural festivals, faith-based organization, school advocacy initiative, radio and television jingles (fao, 2012), social media platforms and short message service (nzeadibe and ajaero, 2011). the ownership of all the water projects including those installed by politicians should be specified. it will be better to transfer ownership to the state government because it is closer to rural communities than federal government and also, the funding of projects is done by the state government. however, the local government should be made to monitor their water facilities through community water committee. the committee will report any dysfunction, failure and maintenance need of the water facilities in their community to the local government. the water committee in each community should be appointed by the traditional rulers and approved by the local government chairman. in this way, the monitoring of water facilities will be the responsibility of the community it is servicing. water guards should be employed as substantial staff of the local governments. the guards will have the responsibly of monitoring water facilities and sources of water to ensure that there is no vandalism and pollution of water sources. the water committee in each community will be made to supervise that guards and report to the local government. the concerned state government institutions should commence the study, design and construction of new water supply systems using technologies that have been developed as appropriate responses to the physical environment conditions in the area. provision of more boreholes and wells in villages would help reduce the trekking distance to where boreholes are sited as well as streams and spring. proper study should be done before drilling new boreholes. wells are quite easier to construct and relatively cheaper therefore, wells should be provided also as alternative to boreholes should they break down. local craftsmen should be trained on how to drill and repair boreholes and other water facilities. borehole drilling is still very difficult in the study area because the expertise is lacking. in the nigerian energy sector, ajao et al. (2009) advocated for the training of local craftsmen on how to install and maintain power facilities to enhance mass production and subsequent commercialization of power. in line with this, training local craftsmen will reduce costs of labor in the water supply facility installation and maintenance. restoration of all village tanks that were formally connected to springs should take effect immediately. these tanks such as the nkwo spring tank in awgu autonomous community were provided by the colonial administration however, after independence they were all neglected. also, addressing the problem of poor service coverage and aging water infrastructure should be targeted. water supply infrastructures are essential to taping local capacities to contribute to social and economic development and crucial to delivering long-term water security. sustained investment in water infrastructure is an essential pillar for developing countries (wwc, 2015). conserving water to reduce water waste is a first step in water management (rahman et al. 2012). thus the communities should adopt various water conservation measures such as installing concrete tanks in springs to avoid the waste of the spring water especially in dry seasons when water yield from these springs are low and to protect it from contamination (khastagir and jayasuriya, 2010). harvested rainwater can be an alternative source in the dry season. households should install large tank particularly underground tanks for collection of rain water in the wet season which can be used when springs and streams yield small quantity of water in the dry and also household water treatment should be encouraged (vohland and barry, 2009). private individuals, groups or organizations in the area should also partake in water supply development by placing taps where villagers can fetch water. in addition, government should encourage private water supply development by providing soft loans to those who will to develop the water resources in the area. conclusions this research has shown that the factors affecting water supply in southeastern nigeria are mainly physical environment barriers, water infrastructural deficit, socio-economic problems geographic location and management bottlenecks. the research recommends that factors responsible for rural residential water supply shortage … 31 water development in rural communities should be a stepwise process; each stage should correlate with physical environment conditions and socio-economic realities. sequel to the fact that majority of the people in the study area are engaged in subsistence farming and other extractive economic activities with very low economic and educational base, it will be more sustainable not to install multimillion high-tech water facilities that the community does not have the capacity to partake in their provision and management. no doubt community participation is a precondition for sustainability, i.e. to achieve efficiency, effectiveness, equity, and reliability (harvey and reed, 2007) however it requires ongoing motivation for continuing participation (batchelor et al., 2000). communities may have participated in the water supply planning process however this does not mean that they will sustain participation in service delivery or that they will successfully manage water supply. community management is a development plan whereby community members assume control-managerial, operation, and maintenance responsibility for the water system (doe and khan, 2004). the beneficiaries of the water supply have full responsibility, authority, and control over it (harvey and reed, 2007). studies in sub-saharan africa showed that communities participated in the planning and provision of water projects when motivated but they are unwilling to manage them and also they lack the education and technical know-how to make an informed decision on management (batchelor et al., 2000; doe and khan, 2004; harvey and reed, 2007). as a first step, traditional sources sustenance intervention should be launched. about 80% of rural households in sub-saharan africa depend on traditional sources (hand dug well, stream, river, pond, spring etc.) some of which they have discovered or occur naturally in their locality (harvey and reed, 2007; fao, 2012), these sources can be developed and upgraded to provide sustainable access to safe water. full information on all possible options should be provided to community members and private sector in order for them to decide on the most suitable technology and service level for them. next, government should sponsor the training of the local people on installation and maintenance of mini water systems such as hand pump and borehole. later, mini water supply system (borehole, hand pump) that can serve small area such as group of households can be introduced. as the community progress along a developmental path and the economic, educational and technical base of the people have improved considerably, high-tech facilities may be deployed. this stance does not infer that all people do not have equal right to water but that water supply in rural areas should be development in stages each stage corresponding with the community’s participatory and management capacity so that the water supply facilities will be maintained after installation except if government, donor agencies or private bodies that install them are also willing and ready to make them work regularly. references adewuyi, a.p. 2013. state-local government collaborative partnership in rural infrastructural development in katsina state, 1999-2102, nigerian journal of social sciences 9(2) 73–93. ajao, k. r., ajimotokan, h. a., popoola, o. t., akande, h. f. 2009. electric energy supply in nigeria, decentralized energy approach, cogeneration and distributed generation journal, 24(4), 34–50. ajayi, j.o., sonuga, f.a., aliboh, o.p., oloke, d.a. 2003. sustainable portable water supply to nigerians through conjunctive development of surface and groundwater resources, national mining and geological society 2 (1) 9–17. anyadike, r.n.c. 2002. climate and vegetation in: ofomata, g.e.k (ed.). a survey of the igbo nation. africana fep, onitsha anyadike, r.n.c. 2009. statistical methods for the social sciences, spectrum books limited, ibadan bakalian, a., jagannathan, n. v. 1991. institutional aspects of the condominial sewer system. washington, dc: infrastructure and urban development department bakalian, a., wakeman, w. 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a. 2005. a desktop study on the cultural and religious uses of water using regional case studies from south africa. department of water affairs and forestry, pretoria, south africa. http://www.wsp.org/sites/wsp.org/files/publications/global_ruralreport.pdf http://www.wsp.org/sites/wsp.org/files/publications/global_ruralreport.pdf http://dx.doi.org/10.1016/j.jhydrol.2009.11.040 http://dx.doi.org/10.4314/jmg.v42i1.18840 http://dx.doi.org/10.4314/jmg.v42i1.18841 http://dx.doi.org/10.1016/j.resconrec.2011.12.002 http://dx.doi.org/10.1016/j.landusepol.2005.05.005 http://dx.doi.org/10.1016/j.watres.2011.04.029 http://dx.doi.org/10.1016/j.desal.2011.01.022 http://dx.doi.org/10.1038/nclimate1556 introduction study area methods questionnaire survey key informant (stakeholders) interview focus group discussions (fgds) analysis of data collected results characteristics of respondents assessment of water demand and supply in the study area descriptive analysis of contributing factors most important factors important factors less important factors pca analysis of the contributing factors physical environment and inadequate water supply infrastructure socio-economic and geographical location management and socio-cultural problems discussion conclusions references journal of environmental geography journal of environmental geography 8 (1–2), 23–30. doi: 10.1515/jengeo-2015-0003 issn: 2060-467x characteristics of point-bar development under the influence of a dam: case study on the dráva river at sigetec, croatia tímea kiss*, márton balogh department of physical geography and geoinformatics, university of szeged, egyetem u. 2-6, h-6722 szeged, hungary *corresponding author, e-mail: kisstimi@gmail.com research article, received 20 february 2015, accepted 1 april 2015 abstract before the extensive engineering works the dráva river had braided pattern. however in the 19-20 th centuries river regulation works became widespread, thus meanders were cut off, side-channels were blocked and hydroelectric power plants were completed. these human impacts significantly changed the hydro-morphology of the river. the aim of the present research is to analyse meander development and the formation of a point-bar from the point of view of indirect human impact. series of maps and ortho-photos representing the period of 1870-2011 were used to quantify the longterm meander development, rate of bank erosion and point-bar aggradation. besides, at-a-site erosion measurements and grain-size analysis were also carried out. as the result of reservoir constructions during the last 145 years floods almost totally disappeared, as their return period increased to 5-15 years and their duration decreased to 1-2 days. the channel pattern had changed from braided to sinuous and to meandering, thus the rate of bank erosion increased from 3.7 m/y to 32 m/y. on the upstream part of the point-bar the maximum grain size is 49.7–83.4 mm and the mean particle size is 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7–39.9 mm and mean sediment size decreased to 6.1 mm. due to the coarse sediment supply and the decreasing stream energy the point-bars develop quickly upstream and laterally too. keywords: point-bar, meander development, gravel-bar, grain-size distribution, effects of dams introduction the number of hydroelectric power plants and their reservoirs built on rivers is increasing worldwide due to their sustainable power production, however no one should ignore their environmental effects (bonacci and oskorus, 2008). the major effect of hydroelectric power plants and reservoirs is the interruption of the continuity of sediment transport processes, thus the river system will be disconnected (ristić et al., 2013). the disconnection is manifests in the form of flow regime alteration, changing in slope and velocity, which result in altered stream power conditions (kiss and andrási, 2011). behind the dam, in the reservoir the power of the flowing water significantly decreases, thus most of the sediment (33-99%) retained, thus the reservoir is slowly filled up (peter, 1997; petts and gurnell, 2005; woodward et al., 2007). usually on the downstream section the hydrology becomes more even, as the height and frequency of floods decreases, whilst the height and duration of low stages increases (williams and wolman, 1984; petts and gurnell, 2005; lajolie et al., 2007). downstream of the reservoirs the process of “clean water erosion” is significant (knighton, 1998), therefore accelerated lateral or vertical channel erosion takes place (williams and wolman, 1984; petts and gurnell, 2005). as the result of the accelerated erosion and the controlled (usually decreased peak) discharge the river mobilizes the smaller particles from the riverbed, thus the bed-material gets coarser, therefore bed armour develops (dietrich et al., 1989). these processes alter the morphology of the rivers, therefore very often downstream of the reservoirs the channel pattern changes (gregory and park, 1974; williams and wolman, 1984; xu, 1996; brandt, 2000; magilligan et al., 2008), or the rate of the processes (e.g. meander development) alters (shields et al., 2010; blanka, 2009). some of the hydroelectric power plants are peak-operated, thus during the main hours of energy consumption mini-floods are generated resulting in the mobilisation of the bed-load and modification of the bedforms (merritt and cooper, 2000; kiss and andrási, 2011). the spatiality and temporality of the bed processes could be evaluated by analysing the grain size of the bed-load (belal, 2015). the gravel-bars in rivers are sensitive indicators of the altering fluvial morphology caused by dams, as they could be destroyed by floods or stabilised by vegetation (fergus, 1997; xu, 1997). the main reason of the formation of fluvial bars is the local decrease in flow energy (sipos, 2004). during the bar development the first step is the deposition of coarse bed-load sediment in the space between the highenergy transportation routes, later in the low-energy zones finer sediments also trapped behind the large gravels (leopold and wolman, 1957). around the evolved form the 24 kiss and balogh (2015) flow splits, which results in increased bank erosion. due to the lateral erosion the river widens locally, thus it loses energy (ferguson and werrity, 1983). ashmore (1991) made laboratory experiments and measurements to understand the dynamics of the bar formation. there are two main types of river bars (balogh, 1991). the first group is located in the middle of the river, and the mid-channel bar, the crescent-shaped bar, the longitudinal bar and the transverse bar belong to this group. the second group is located along the banks and this group consists of the point-bar and the side-bar. the diagonal bar is a transitional form between these two groups (knighton, 1998), though by time all these bar types can transform into each other, which makes their identification difficult. according to dykaar and wigington (2000) the spatial and temporal variations of the river bars causing braiding are determined by the speed of accumulational and erosional processes, and variations of discharge. human activities have been altering the hydrology and the morphology of the dráva river since the 19 th century. first the large meanders were cut-off resulting in metamorphosis, as the meandering pattern became braided (kiss and andrási, 2014). in the 20 th century the regulation was completed by revetment and groynes constructions, side-channels blockages, and construction of reservoirs and hydroelectric power plants. these engineering works altered the water and sediment regime of the river, leading to morphological alterations. the aim of our research is to study the formation of a meander in detail, and to evaluate the role of indirect human impact in meander development. study area the dráva river springs in the tyrolean alps and runs to east, so after 749 km it flows into the danube. its catchment area (40,489 km 2 ) extends to five countries. the area studied in detail is downstream of the confluence of the dráva and mura rivers (fig. 1), near to the croatian village sigetec (at 220–222 fluvial km). the selected meander is just 26 km downstream of the donja dubrava hydroelectric power plant, thus its indirect effects could be studied in detail, whilst no other direct or indirect human impact affected the evolution of the bend. the slope of the studied section of the dráva river upstream of őrtilos gauging station is 80–130 cm/km, whilst along the studied section it decreases to 45–55 cm/km (kiss et al., 2011). the mean discharge of the river is 510 m 3 /s and the rate of sediment transport (280,862 t/y) is recently only the 28% of the amount it used to be before the construction of nearby hydroelectric power plants (bonacci and oskorus, 2008). the grain size of the bedload decreases downstream: cobbles with a diameter of 6-8 cm are frequent, though only coarse sand appears near barcs, and at the confluence of the danube and dráva rivers the dominant fraction is sand (kiss and andrási, 2012). the hydro-morphologic properties of the dráva have been greatly altered during the last one and half centuries (kiss and andrási, 2012). between 1784 and 1904 altogether 65 meanders were cut off shortening the original length of the river by 185 km, the last cut-off was made in the 1990’s (remenyik, 2005). several banksections were stabilized, and groynes were built to block side channels and to support shipping, especially downstream of barcs. since 1910’s numerous (22) hydroelectric power plants have been constructed on the austrian, slovenian and croatian section of the dráva river. the croatian hydroelectric power plants were built between 1975 and 1989, significantly changing the flow and sediment regime of the river (bonacci and oskorus, 2008). as a result of these regulation works the frequency of the floods decreased (kiss and andrási 2011). in the study area the lowest, donja dubrava hydroelectric power plant generates 1.5–1.7 m high “mini floodwaves” twice a day due to its peak-hours operation. fig. 1 the studied meander is located east of sigetec, on the croatian section of the dráva river methods the hydrological changes of the dráva were evaluated based on daily stage data measured at the barcs gauging station since 1900. the frequency curves of the stages were made for each decade to evaluate the hydrological changes. as floods are very important forces in the fluvial system, the number of flood-days (over 420 cm) and their return period were also calculated. the long-term development of the selected meander (section) was studied based on a map series containing the third military survey (1870), the maps of the hydrological atlas of the dráva (1966), topographical maps (made in 1944 and 2001) and an ortho-photo (2011). these maps were geo-corrected using erdas imagine 9.1 and quantum gis 2.8., as they were made using different scale and projection systems. the average channel width of the dráva was defined as the ratio between the area of the polygon between the bank-lines and the centreline. the lateral erosion was calculated based on the area of the polygon between bank-lines surveyed at two different times. the arch-length was measured between two inflection points along the centreline, whilst the chord length was measured directly be characteristics of point-bar development under the influence of a dam … 25 tween the two inflection points. the amplitude refers to the size of the meander, as it is the greatest perpendicular distance between the chord and the centreline. the radius of curvature is the radius of the greatest circle fitted into the meander’s centreline. the development stage (β) of the meander was determined after laczay, as the ratio between the centreline and the chord length. the short-term bank erosion was measured annually between october of 2013 and january of 2015. field measurements were made using the real time kinematic network and the topcon total station theodolite with a centimetre accuracy. recently several researches attempt to derive the grain size distribution using digital images (butler et al., 2001; carbonneau, 2004; graham et al., 2005; chang and chung, 2012) and we also applied this technique. in a lowstage-day we took 68 digital photos placing a reference frame (40*40 cm) on the dry gravel surface. the photos were imported into the digital gravelometer software, then the properties of the camera were given, finally we defined the corners of the reference frame. the programme calculates the grain-size distribution of the bar surface. during the study the wentworth scale was applied. results and discussion hydrological changes of the dráva river based on the characteristics of the hydrology the dataset of 1901-2012 could be divided into three periods. the first period (1901-1917) could be considered as almost natural, as nor the floods, neither the lower stages reflected decreasing tendency. this is reflected by the overlapping frequency curves (fig. 2). at the beginning of the 20 th century floods returned in every year and they covered the floodplain for 2-3 weeks (in 1904: 54 days). within a year floods normally were rapid and their return period was 4-6 months. in the second period (1918-1967) the average and minimum stages show decreasing trend, as they decreased by 90-100 cm, and the frequency curves also shifted down. the stage of the floods did not change considerably, though they became shorter and in some years they did not even occur, thus their return period increased to 1.4-2 years. in the last period (1968-2012) the above described processes became more pronounced, which became especially characteristic after the beginning of the operation of the varasd (1976) and donja dubrava hydroelectric power plants (1989). the average and minimum stages decreased further by 130 cm, the height of highest stages did not reach the edges of the banks (thus floods disappeared). the frequency curves shifted down characteristically, so for example in the 2000-2010 decade stages were higher than 100 cm occurred just only in 20% of the period, though they were in 100% in the 1900-1910 decade. floods almost totally disappeared, as their return period increased to 5-15 years, and their duration decreased to 12 days (fig. 3). long-term meander development at the time of the third military survey (1870) the studied dráva section had braiding pattern (fig. 4) and the flow was split between 5 islands. the width of the channel varied between 536–1813 m. between 1870 and 1942 the morphology of the river reach changed, as the braided pattern was replaced by meandering, and the islands melted to the banks. the channel width decreased by 85–87%, as in 1942 it was only 81–225 m. the arch-length of the meander was 1573 m, the chord length was 1489 m, the amplitude was 239 m and the radius of curvature was 931 m. according to the meander classification method of laczay the studied meander belonged to the group of “juvenile meanders” (β=1.06). the pattern change was probably caused by the regulation works, which terminated the braiding and created a meandering single-bed river. until the next survey (1968) the channel became wider, as the maximum channel width (266 m) increased by 18% and the minimum width (90 m) increased by 11%. the rate of lateral bank erosion varied between 3-40 m (0.1-7.3 m/y), and its average was 3.7 m/y. all horizontal parameters meander decreased between the two surveys (1942–1968). the arch-length of the meander (1025 m) decreased by 35%, the chord length (988 m)decreased by 34%, the amplitude (95 m) became smaller by 60%, and the radius of curvature (857 m) also decreased by 8%. the meander based on its β value (1.04) still remained juvenile. fig. 2 frequency distribution curves of decadal stages (a) and height (cm) of different stage frequencies (b) based on the dataset of barcs gauging station 26 kiss and balogh (2015) by 1977 the studied section did not change considerably, however the meander upstream of the studied bend became sharper (decreased chord length and radius of curvature), thus it rapidly migrated downstream, thus the reach became more sinuous. the maximum width (247 m) of the studied meander decreased by 7 %, though the minimum width (108 m) increased by 20 %, thus the channel became more uniform. as the thalweg became more pronounced due to the shift of the upstream meander, the average rate of bank retreat increased to 5.6 m/y (151%). during the meander migration the erosion (11 ha) exceeded the accumulation (7 ha). all values of the horizontal parameters increased: arch-length became 1441 m (41%), chord length 1407 m (425), amplitude 140 m (47%), radius of curvature 1101 m (28%). as the parameters increased by the same rate, the shape of the meander did not change significantly (β=1.03), it remained a juvenile meander. between 1977 and 2001 the studied meander changed considerably, as it migrated downstream and a well-developed point-bar system evolved. the width of the channel decreased, as its maximum (216 m) and minimum (103 m) width reduced by 13% and 5% respectively. the annual rate of the lateral shift exceeded the former period by 4% (5.8 m/y). the greatest rate of the lateral migration increased by 72% (11.4 m/y) and the minimum decreased by 50% (0.1 m/y). the rate of the accummulational and erosional processes has been greatly increased, as the eroded area was 29 ha (+164%) and accumulated area was 38 ha (+443%). most of the fig. 3 yearly number of flood (>420 cm ) days (a) and the return period of floods (b) at barcs gauging station (1901-2013) fig. 4 long-term meander development of the studied section characteristics of point-bar development under the influence of a dam … 27 horizontal parameters decreased, for example the archlength of the meander decreased by 13% (1254 m), the chord length by 16% (1177 m), and the radius of the curvature by 9% (999 m), meanwhile the amplitude increased by 33% (186 m). the β value increased to 1.07, indicating slow meander development. between the 2001 and the 2011 surveys the meander developed further on. the maximum channel width decreased by 11% (192 m) and the minimum decreased by 22% (80 m). the average rate of lateral shift was 9.5 m/y, which exceeded the former period by 64%. the maximum rate of the bank erosion was 189 m (18.9 m) and the minimum was 1 m (0.1 m/y). during the lateral migration the total amount of erosion was 14 ha, whilst the area of the point-bar increased by 18 ha, which means that the rate of these processes decreased by 5253% and there was a net accumulation on the studied area. the former processes continued, as the arch-length of the meander decreased by 10% (1129 m), the chord length by 18% (965 m), the radius of curvature decreased by 34% (661), though the length of the amplitude increased by 24% (230 m). the meander became well-developed (β=1.17). short-term meander development between the snapshot of the ortho-photo (2011) and our first field survey (2013) the rate of the bank erosion was 2–40 m (1–20 m/y). in the following 15 months the rate of bank erosion has increased to 32 m/y (fig. 5). between the two field measurements (2013 and 2015) the area of eroded floodplain was 20.6 ha, which exceeds every previous data. the rate of bank erosion was spatially diverse, as it greatly increased downstream. fig. 5 short-term bank erosion on the study area between 2011 and 2015 grain size analysis of the point-bar during the last almost 30 years a large point-bar system developed in the meander. the older surfaces were colonised by riparian forest, however the youngest point-bar surfaces are still bare, which enabled us to make superficial grain-size measurements. most of the surface (73%) of the point-bar is built of pebble (4–64 mm), some areas (16%) are covered by granule (2–4 mm), 11% by sand, and only 0.1% of the area consists of cobbles (>64 mm). the mean grain size of the whole point-bar is 6.6 mm, and the biggest cobble has a diameter of 123.9 mm. the material of the bar-system is moderately sorted (fig. 6). large grains appear in well defined areas, as on the upstream and central part of the point-bar, and in the secondary channel between the bank and the bar. the maximum grain-size decreases downstream: in the upstream part of the bar-system 100–120 mm large cobbles were deposited, whilst downstream the maximum sediment size decreased to 40–65 mm. this decrease does not show a linear trend, because the bigger sediment was deposited in patches and in between these patches fine-grained gravel aggraded. it suggests that the point-bar is built up of three smaller bar-heads, which were formed together. the grain-size of the sediment is altering not only downstream, but laterally too. on the edges of the point-bar close to the thalweg the sediments are finer grained (50–90 mm) than those (60–120 mm) located closer to the bank-line. this could develop during high energy conditions, when during high stages the river could transport coarser sediments near the convex bank and in the side channel, but as the stage fall, these sediments remained in their location. however, closer to the thalweg the daily mini flood-waves generated by the power plants could transport further the coarse sediment, thus at the fall of the mini flood-waves finer grained bed armour develops. based on the grain-size distribution of the bare surfaces the point-bar could be divided into three parts (fig. 6). on the upstream third of the active bar samples are coarser (mean grain-size: 7.6 mm) than the mean grain-size (6.6 mm) of the whole point-bar. the maximum grain size of this area varies between 49.7 mm and 83.4 mm, thus most of the sediment (78.5%) consists of pebbles. the material of this area is moderately sorted (s=1.7). on this area of the point-bar there is a clear tendency of decreasing grain-size toward downstream. on the middle part of the point-bar where the mean grain size reduces to 6.7 mm, the maximum grain-size of the samples varies between 38.9 mm and 123.9 mm. almost 74% of the sediments consists of pebbles. the material of this surface is also moderately sorted (s=1.8), but slightly better than in the upstream part. there is a decrease in grain-size towards downstream, however it is not continuous as it is in the upper part, because this central part is dissected by coarser and finer sediment patches referring to smaller bar-heads. the mean grain size of the downstream part of the point-bar is finer (5.5–6.6 mm). the maximum grainsize is smaller (39.9–69.7 mm) than in the two upper parts, thus the proportion of pebbles decreases (70%). the material of this area is better sorted (1.9). from the point-of view of grain-size distribution the side channel between the stabilised point-bar surfaces is diverse, as here the mean grain-size varies 28 kiss and balogh (2015) between 4.9 mm and 7.8 mm. here the largest particles are 44.3–103.8 mm. the maximum grain-size of the side channel decreases downstream: its upper is characterised by 70–100 mm large grains, whilst towards downstream it decreases to 50–70 mm. the material of the side-channel is 7moderately sorted (s=1.8). the varieties in grain-size distribution of the side-channel refer to high energy conditions during water cover (during the mini flood-waves), which transport large grains into the side-channel in the form of mid-channel bars. these bars slowly will aggrade the side-channel, thus the island will amalgate into the stabilised surface of the point-bar. conclusion the hydrological analysis proved, that the floods gradually disappear from the dráva river, thus the fluvial development of the floodplain will terminate. at the same time the stage of the mean and low stages decreases (by stabile discharge; kiss and andrási, 2011), which refer to rapid incision. these hydrolog ical changes started when the first hydropower plants were constructed, but they were accelerated when the varasd (1976) and donja dubrava hydroelectric power plants (1989) started to operate. these hydr ological changes triggered morphological changes too. the analysis proved that the meander development and point-bar formation downstream of the donja dubrava hydroelectric power plant is specific. in the 19 th century (1870) prior the regulations the dráva river had natural hydrological and sedimentological regime, thus braided pattern developed. however by the end of the 19 th c. and in the 20 th c. river regulation works became widespread, thus meanders were cut off, and side-channels were blocked. their effects were emphasized by 20 th c. dam constructions. as a result, the morphology of the river changed, as the braided river developed into a single-thread sinuous channel. the channel continuously narrowed, referring to more pronounced thalweg. due to the sediment retention of the reservoirs clean water erosion became dominant, causing incision and simultaneous channel narrowing. as the sinuosity of the bend increased, the rate of erosional and depositional processes increased too. because of the permanent drop in water stages, vegetation could stabilise the developed point -bars. these processes became accelerated since the end of 1970’s, when the last members of the dam-reservoir system were built. probably due to the 1.5–1.7 m high “mini floodwaves” twice a day generated by the nearby donja dubrava hydroelectric power plant bank erosion accelerated, despite of the fact, that real floods a lmost disappeared. the accelerated bank erosion is also influenced by the incision and the previous fl uvial history of the area: the meander develops in the loose material of the former braided channel, thus it is easy for the dráva to erode the young and unco nsolidated material. the incision, the development of the thalweg and the intensive bank erosion create favourable co nditions for point-bar development since the end of 1970’s (fig. 7). the dráva sorts its bed -load material downstream and laterally too. the maximum and mean grain-size decreases downstream and also laterally towards the bank. on the upstream part of the point-bar the maximum grain size was 49.7–83.4 mm and the mean sediment size was 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7–39.9 mm and mean sediment size decreased to 6.1 mm. along the bank and in the side channel coarser sediment was deposited, as here the maximum grain size is 38.9–123.9 mm and 44.3– 103.8 mm respectively. fig. 6 mean (a) and maximum (b) grain-size of the studied point-bar. a: slip-face of a bar; b: island-core; c: bare point-bar surface; d: water surface; e: zones of the active bar characteristics of point-bar development under the influence of a dam … 29 fig. 7 annual rate of bank erosion on the study area greater grains deposited in the upstream end of the point-bar, where the flow is diverted towards the main thalweg and into the side-channel, thus its energy drops. in this way the bar-system expands laterally and also towards upstream. the upstream expansion of the pointbar system is contradictory with the meander development of the sandy bed-load rivers, where the main location of the accumulation is at the downstream part of the bar (sipos, 2006; kiss and blanka, 2011). acknowledgements the research was supported by the otka 100761 research found and the jános bolyai research scholarship of the hungarian academy of sciences. references ashmore, p. e. 1991. how do gravel-bed rivers braid? canadian journal of earth sciences, 28(3), 326–341. doi: 10.1139/e91-030 balogh, k. 1991. szedimentológia (sedimentology). budapest, akadémiai kiadó, 547 p. 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(ed.) large rivers. wiley, chichester, 261–292. xu, j. 1996. underlying gravel layers in a large sand bed river and their influence on downstream-dam channel adjustment. geomorphology 17, 351–359. doi:10.1016/0169555x(96)00012-8 xu, j. 1997. evolution of mid-channel bar sin a braided river and complex response to reservoir construction. an example from the middle hanjian river, china. earth surf. processes landf. 22, 953–965. doi: 10.1002/(sici)10969837(199710)22:10<953::aid-esp789>3.0.co;2-s automatic drought tolerance measurement of the soil-living microarthropod, folsomia candida journal of environmental geography 16 (1–4), 46–54. doi: 10.14232/jengeo-2023-44683 issn 2060-467x automatic drought tolerance measurement of the soil-living microarthropod, folsomia candida lászló sipőcz1*, andrás ittzés2, miklós dombos1 1institute for soil sciences, centre for agricultural research, elkh, herman ottó út 15., 1022 budapest, hungary 2hungarian university of agricultural and life sciences, institute of mathematics and basic science, villányi út 29-43., 1118 budapest, hungary *corresponding author: sipocz.laszlo@atk.hu research article, received 15 may 2023, accepted 19 july 2023 abstract soil is a complex habitat where microarthropods, such as mites (acari) and springtails (collembola) species occur in high number and species diversity. microarthropods play an essential role in organic matter decomposition and provide an important ecosystem service in soil. the soil-dwelling microarthropods are sensitive to environmental changes; therefore, their ecological characteristics are used to evaluate soil conditions. in modern environmental ecology, several species are involved in assessing the ecological consequences of drought periods. the growth rate is a standard sublethal parameter by which the body size of individuals is measured. extracting microarthropods from the soil is difficult and time-consuming, requiring a high amount of human resources. only a few samples can be processed due to laboratory limitations and high costs. however, nowadays the rapidly developing artificial intelligence (ai) technologies promise new opportunities in many research areas. data on soil-dwelling microarthropods could be collected quickly and automatically using our new digital soil extractor device, the edapholog, equipped with image analysis based on ai. this device recognizes living individuals, classifies them, and measures their body length automatically. using this system, the growth and reproductive success of various species in the same experimental culture could be rapidly and simultaneously monitored. in this study, we aimed to analyse the applicability of the edapholog for measuring the body size of collembola species and folsomia candida through a set of drought tolerance tests with three soil moisture treatment levels. moisture content was set based on the maximum water holding capacity (wmax) of the soil applied. the three levels were set to wmax:35%, 40%, and 50%. furthermore, we aimed to test the reliability of the detection and recognition of the species and the accuracy and reliability of the automatic body size measurement of individuals. significant correlation (r= 0.94) exists between the automatically and manually measured body sizes. although the different soil moisture treatments did not show marked differences in the collembolan body sizes between the moisture treatments, we found a significant difference in the reproduction rates between w50 and the other two (w35 and w40) treated groups. the edapholog can greatly contribute to quick and precise data extraction and can have vast applicability in environmental ecology. keywords: ecotoxicology, artificial intelligence, microarthropods, folsomia candida, drought tolerance introduction the more is known about the ecological processes of the soil, its vulnerability becomes more apparent. soil provides clean air, food, and water; therefore, the importance of its protection is evident (pereira et al. 2018). the soil-dwelling mesofauna (mainly microarthropods) plays an essential role in the decomposition of plant organic matter and nutrient cycling in the upper layer of the soil (briones 2014). microarthropods (mainly mites and springtails) feed on soil-dwelling fungi and other microbes and play a topdown regulatory role in the decomposing food chains (coleman et al. 2017). the mesofauna is present with a huge number of individuals (~105/m2) and species in many types of habitats. they also influence the nutrient exchange processes of the soil. so they can indirectly play a significant role in the quantitative regulation of the sequestration of atmospheric carbon dioxide (filser 2002). soil-dwelling microarthropods react sensitively to various soil conditions and pollution; therefore, they are potential bioindicators (brussaard et al. 2007, briones 2014). generally, the more intensive the soil life, the healthier the soil is (menta et al. 2018). extreme weather events resulting from global climate change have become one of the most significant problems recently (steffen et al. 2007). adapting to these events and mitigating their effects is necessary (kardol et al. 2011, makkonen et al. 2011, meehan et al. 2020). the biodiversity and organic matter of soil are highly dependent on the soil moisture level. drought periods seriously impact the diversity of species living in the soil and threaten essential ecosystem services. without soil-dwelling microarthropods, organic matter formation may decrease, atmospheric carbon dioxide sequestration levels may slow down, and the water retention capacity of soils may also deteriorate (bardgett 2005, briones 2014). therefore, there is an increasing need to study the influence of drought on soildwelling mesofauna. https://doi.org/10.14232/jengeo-2023-44683 mailto:sipocz.laszlo@atk.hu sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. 47 however, examining soil-dwelling microarthropods is quite complicated and labour-intensive. still, today's rapidly developing information technology (it) solutions promise new possibilities to solve these difficulties. artificial intelligence (ai) is increasingly popular in various research fields, thus it became popular among scientists, and it could facilitate data collection even by involving lay citizens (silvertown 2009, bilyk et al. 2020). the most popular ai applications in ecology are based on sound and image processing (mallard et al. 2013, liu et al. 2018, christin et al. 2019, flórián et al. 2020, høye et al. 2021, laursen et al. 2021, sys et al. 2022). a new device has been developed by the soil zoological research group at the centre for agricultural research – institute for soil sciences (elkh) and edaphone ltd, using image recognition and ai-based image analysis methods. this device substantially differs from those previous edapholog models that used an optoelectronic ring and ccd camera and functioned as a traditional pitfall trap. those prototypes measured soildwelling mesofauna's activity under field conditions (dombos et al. 2017, gedeon et al. 2017, balla et al. 2020). the new edapholog2022 model is an automatic measuring device that detects microarthropods, takes photos, and measures their body sizes. after that process, it blows the detected individuals off. therefore, edapholog can also be suitable for the measurements of eco-toxicological tests. for eco-toxicological tests, some iso standards exist (iso, 1999; iso, 2006; iso 2011), and some innovative tools and programs have been developed. for example, the collscope developed for eco-toxicological testing, which measures the body sizes of springtails (bánszegi et al. 2014). the digital soil extractor based on ai image processing may help replace human manual work. in addition, the exact detection time can be used as a new dimension, which can play an important role in drought tolerance studies of mesofauna. we performed a laboratory microcosm experiment in which folsomia candida willem 1902 individuals were kept under different soil moisture conditions. the edapholog digital soil extractor examined their sublethal parameters like body size. f. candida is a popular springtail species used in eco-toxicological tests. edapholog is produced by edaphone ltd., and we tested its usability for eco-toxicological tests. the following research questions were answered: 1) is there a difference between the body sizes of animals kept under different soil moisture conditions? 2) can the difference in body sizes be detected with the new device edapholog? and 3) what is the accuracy of the measurement? materials and methods test animal and materials the drought tolerance test was conducted on a synchronized population of f. candida willem 1902 (collembola) individuals, often used in eco-toxicological tests (bayley et al. 2001, lock and janssen 2002, hilligsøe and holmstrup 2003, sørensen and holmstrup 2005). the culture was kept in continuous darkness at 20±°c in a 15 cm diameter plastic tube with a closed lid. at the bottom of the tube was a 1.5 cm thick moistened plaster of paris mixed with activated carbon. the gypsum to activated carbon ratio was 1:8 by volume. the culture was fed once a week ad libitum. the moisture content of the plaster was also adjusted once a week based on the initial weight of the sample holders. according to the plaster's maximum water absorption capacity, it was always restored to 100% hydration every week. synchronization of populations was carried out in a cylindrical box (diameter of 20 cm) with 2 cm of 1:8 mass volume carbon plaster on the bottom. the maximum saturation of the charcoal plaster was achieved by the following: after drying, water was added to the plaster and incubated for 10 minutes. then, water was poured off, and the weight of the container was measured. this weight was always set back with a flask with a spray head. the synchronization was performed by keeping 200-300 adult individuals taken from folsomia candida culture together in this cylindrical box for three days. the collembola laid enough eggs during this time to start the experiment (oecd, 2009). the experimental medium was commercially available general potting soil. the potting soil was sieved according to soil aggregate sizes, then the aggregates within the size range of 2-5 mm were selected to ensure undisturbed extraction of the animals. since potting soils often contain soil-dwelling microarthropods, defaunation had to be carried out, thus, the sieved soil was heat-treated at 108°c for 72 hours. experimental design the experiment was carried out at a constant temperature (20±1°c) with 12-hour-long dark and light periods. the lighting was ensured with cold white led lamps, producing a light intensity of 580-600 lux. the dried soil (20 g) was measured into a 120 ml plastic sample holder (diameter: 5 cm). the moisture content of the samples was set according to the soil's maximum water-holding capacity (wmax). to calculate the wmax, air-dried potting soil samples were taken into three special metal sample tubes. at the bottom of the sample tubes, a moisture-permeable nylon fibre screen fabric was attached. these samples were gradually saturated with water for a week. the weight of the three sample holders containing potting soil saturated with water was measured and then placed on a 6 cm thick layer of sand for one hour. the unnecessary, unbound water leaked out. the samples were dried in a drying oven at 108 °c for 48 hours, and then the weight of each sample holder was re-recorded. the difference in the mass of the potting soil saturated with water and the dried potting soil was the wmax. the three figures obtained this way were used during the subsequent moisture adjustment (oecd, 2009). f. candida is a so-called edaphic species, thus, it lives in the deeper soil layers, in the cracks and pore spaces of the soil, so it is not advisable to set a moisture value higher than 60% of the wmax. for this reason, 50% of wmax was set as the highest soil moisture value. the soils received three moisture treatments, 35% (w35), 40% (w40), and 50% (w50) of the wmax. w35 corresponds to 48 sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. 14.95 v/v%. similar conditions evolved during the drought of 2022, as the average soil moisture in august at a depth of 10 cm was 15.16 v/v% according to the measurement station near kiskunfélegyháza in hungary (“aszálymonitoring” 2023). the soil moisture levels were set in every plastic sample holder one week before the experiment started. ten individuals of 9-12-day-old f. candida were placed in each plastic sample holder. the duration of the experiment was four weeks. the response variables were the body length of the individuals measured manually and automatically. the moisture contents were adjusted in a newly equipped extractable sample holder with three repetitions. the sample holder tube was closed with a screw cap at the top and a rubber cap at the bottom to increase the sealing effectiveness. the rim of the rubber cap was further secured with insulating tape. even so, an average of 0.12 g of water evaporated weekly, continuously replenished during the inspections. the plastic sample holder was also equipped with a 2x2 mm mesh at the bottom, to which a sealing rubber cap was attached. the moisture content of the samples was checked three times a week. the necessary moisture replenishment was based on regular weighing. the test animals were fed with baker's yeast ad libitum three times a week. the samples were placed in a 3x3 grid, and the placement was randomly changed at each check to reduce possible distorting effects. extraction of animals from the sample holder tube was done with a berlese-tullgren funnel. by removing the caps from the bottom, the animals left the samples without disturbance along the vertical gradient of soil drying. the extraction time was two days because of the small amount of soil, which dried quickly. automatic detection of soil microarthropods in this experiment, the new equipment prototyped by edaphone ltd. (esztergom, hungary) was used to extract collembolan individuals from the microcosms. this soil extractor follows the operating principle of the traditional berlese-tullgren funnel (crossley and blair, 1991). a soil sample ‒ without the plastic cap ‒ was placed on a sieve box, and a vertical moisture gradient triggered microarthropods to escape. they fall through a mosquito mesh (2x2mm) and entered the sample holder through a funnel (fig. 1). during soil extraction, soil particles also tend to fall into the sample container. to prevent this, we used a 3 cm layer of gravel. contrary to the traditional soil extractors where microarthropods were captured and killed in a sample container, in this new equipment, microarthropods entered into a plate where they were video recorded. for video recording, the device houses a high-resolution camera (imx477r stacked, back-illuminated sensor, 12.3 megapixels) and a lens (machine vision fa lens, 10 mp, 51.5 mm 1/ 1 /8", c-mount). an image analysis procedure occured on each picture in real-time during video recording. a detailed description of this prototype will be fig.1 the new edapholog device is based on the conventional soil extractor. the soil invertebrates, triggered by drought, move downwards and fall through the sieve box and the funnel. photographing of the individuals (detection and identification) occurs in real-time under the funnel where individuals fall. published in a forthcoming paper. after detection, the microarthropod individuals were removed by an automatic blow-off pump into a sample container containing a preservation liquid (70% ethanol + nonit: 60% dioctyl sulfosuccinate na-salt). thereby, the biological sample could be used for further analysis. automatic measurement of body length the software developed by edaphone ltd. recognizes the animal by pixel extraction calculated by deviation from the background. in the body size estimation process, the first step is to detect the animal. then, the program frames and defines the boundaries of the animal. contour creation is a multi-step process. first, the image is grayscaled, then by setting a threshold value, it is divided into only black and white pixels, and finally, the contour of the detected animal is highlighted. the body size will be the length of the segment connecting the x and y maximum of the contour (fig. 2). twenty automatically measured body size data were obtained for every detected collembolan individual. based on preliminary test measurements, we used the largest measured body length data for folsomia candida. the reason for using the longest body length data is that during their movement, the animals can adopt body positions (turning, taking a defensive position), leading to smaller body lengths measured (fig. 3). registering the time of each measurement was also assigned to each animal as a unique identifier. animals were also measured manually by using the image obtained from the edapholog device (fig. 4). the body lengths were measured with the imagej software by drawing a straight line between the top of the insect's head and the end of its abdomen (ninon et al. 2019). at the beginning of the experiment, ten animals were placed in each sample holder, from which we calculated the reproduction rate (offspring/adult individual). sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. 49 statistical analysis body length values and the reproduction rates of the three different moisture treatments were analyzed using the one-way anova. the dependent variable was the animal’s body size (mm), and moisture treatment was the factor having three levels (w35, w40, w50). data are presented as mean ± standard deviation (sd). collembolan body length values of the two measurement methods (manual and automatic) were analyzed with a pearson correlation model. the large sample sizes (n>30) and the similarity of the variances justify the method’s validity. finally, a bland-altman plot was used to represent the differences between the two measurement methods and the mean values of the measured body length. the ibm spss v.27 (ibpm spss statistics for windows 2020) statistical program was used for all data analyses. fig.3 body positions that cause outliers during automatic body length measurements. fig.4 manual and mechanical measurement of folsomia candida individuals. the red line shows the result of the automatic measurement, while the yellow segmented line shows the manual observation. fig.2 photo transformations for body size estimation. 1: animal framing and clipping, 2: turning the photo into grayscale, 3: splitting the image into black and white pixels, 4: drawing contours, 5: determining the animal's body length, based on maxima in the x and y directions. 50 sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. results drought tolerance experiment the body lengths of 729 individuals were manually measured and analyzed in the drought tolerance experiment (fig. 5). the mean body length (using the manually measured data) in treatment w35 (0.83±0.19 mm; n=139) was similar to the treatment w40 (0.84±0.20 mm; n= 85). in the w50 treatment, the mean body length (0.87±0.22, n=505) was slightly higher than in the lower soil moisture treatments. however, according to the results of the one-way anova, the different soil moisture treatments have no significant effect on the body size of f. candida individuals (f (2;726)=1.681; p>0.05). reproductive success we found a considerable difference in reproduction success based on the number of sample elements of the treatment groups measured during moisture treatments, especially at w50 (fig. 6). while there is no significant difference between w35 and w40, w50 significantly differs from these groups (table 1). comparison of the manual and automatic measurement methods a close correlation was found between the results obtained by the manual and automatic measurement methods of individual body lengths. analysing the data pairs of the manual measurement and the new automatic measurement, we got a strong relationship and a significant regression (pearson correlation: r = 0.94; n = 730; p< 0.001). the average difference between the two measurement methods was 0.13±0.07 mm, which shows a systematic overestimation of body lengths by manual screening. fig.5 effects of soil moisture treatments on the body lengths of folsomia candida based on manual measurements. w35 is 35%, w40 is 40%, and w50 is 50% of the wmax (box depicts means, whiskers: standard errors, se) fig.6 effects of soil moisture treatments on reproduction rates. w35 is 35%, w40 is 40%, and w50 is 50% of the wmax (box depicts means, whiskers: standard errors, se) table 1 results of anova between the three moisture treatment levels on the reproduction rates (abbreviations: ss= sum of squares, ms= mean of squares) effect univariate results for each dv (reproduction) sigma-restricted parameterization effective hypothesis decomposition degree of freedom reproduction ss ms f value p value intercept 1 453.69 453.69 53.9679 0.000326 moisture 2 348.08 174.04 20.7027 0.002028 error 6 50.44 8.41 total 8 398.52 tukey hsd test; variable reproduction (reproduction) approximate probabilities for post hoc tests error: between ms = 8.4067, df = 6.0000 cell no. moisture w35 w40 w50 3.6333 1.8333 15.833 1 w35 0.739079 0.005207 2 w40 0.73908 0.002684 3 w50 0.00521 0.002684 sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. 51 after transforming the automatic measurement data based on a fitted linear regression (y = 1.026x + 0.1181), we found no significant difference between the two measurement methods (fig. 7). the bland-altman plot can be used to compare data measured by different methods. it can also show whether one measurement method can be substituted for another. the two methods show minimal differences apart from a few outliers when comparing body length data obtained by manual and automatic measurements (fig. 8). overall, the average of the measurement differences depicted on the bland-altman plot remained in a narrow range. hence, the difference between the results of the measurement methods is low. discussion drought tolerance significant differences were found among the reproduction rates of the tested collembola species, especially the w50 setting showed conspicuously higher specimen numbers than the other treatments. the specimens had proper conditions before the experiment started, but then, they were exposed to sudden drought stress in the w35 and w40 treatments. the fauna may not have enough time to adapt to the low moisture conditions. drastic and sudden drought rarely occurs in nature; therefore, the animals normally have time to adapt to the circumstances. the survival rate of springtails with time to adapt to drought or extreme temperatures is much higher than those exposed to sudden stress (sjursen et al. 2001). however, f. candida can survive mild drought effects (hilligsøe and holmstrup 2003b), which may explain the reproductive success similarity between the treatments w35 and w40. unlike the reproduction rate, the drought tolerance test did not yield any significant changes in body size. in the experiment of szabó et al., (2022; oecd, 2009), body sizes of folsomia candida were also similar between the fig.7 effects of soil moisture treatments on the body lengths of folsomia candida based on manual (blue) and automatic measurements (red). the green columns depict the automatic measurements after transforming the data (by using linear regression (y = 1.026x + 0.1181). w35 is 35%, w40 is 40%, and w50 is 50% of the wmax (box depicts means, whiskers: standard errors, se lower moisture treatments; however, these collembolans got selenium treatments besides the drought stress. in our experiment, the survival and body size of grounddwelling springtails were less affected by drought than the reproduction rate, similar to what has been shown for the dry mass of f. candida in the study of wang et al. (2022). nowadays, sudden drought events are becoming increasingly severe, affecting soil health, and therefore some ecological services can be seriously damaged. by measuring the microarthropods found in the soil, we can infer the current state of each soil, therefore, it is important to analyse these organisms. although no significant difference between the body sizes were found during the experiment, the reproduction rate showed a significant difference in this case, as already shown in a previous study (wang et al. 2022). fig. 8 bland-altman plot for comparison of the automatic and manual measurements 52 sipőcz et al. 2023 / journal of environmental geography 16 (1–4), 46–54. the number of samples that can be processed can be greatly increased using the new device since the data can be processed immediately during extraction we can get. on the other hand, currently, sample processing after extraction can take weeks. measurement methods our new digital extractor with edapholog provides a novel approach that automatically measures microarthropods and estimates their body size. this device shows many novelties compared to previous automatic measurement methods. one of its advantages is that edapholog registers 20 body-length data for each individual. compared to another body size detecting device, e.g. collscope, which saves only eight body length data (bánszegi et al., 2014), the new device tested in our study provides a higher number of measurements and hence better reliable because more data is available to choose the right body size the animal has a greater chance of turning into the ideal body position. scientific studies related to automatic species identification and body size estimation have previously been published, showing that they can be well applied in practical ecology for measuring aquatic and terrestrial organisms in both field and laboratory conditions (finlay et al. 2007, agatz et al. 2015, duckworth et al. 2019, laursen et al. 2021). collscope measured every individual in 30 seconds, and the measurement was semiautomatic as one person had to manage the device; the edapholog device is automatic, and an individual's measurement lasts just for 2 seconds. automatic measurements are usually performed on preserved individuals in a sample (sys et al. 2022). the other advantage of edapholog is that the animals can be used and extracted alive to be suitable for long-term ecotoxicological or drought tolerance studies and large sample numbers to work. this aspect makes edapholog suitable for setting up long-term experiments with several generations of the test species. in addition, our new sample holder ("extracting sample holder") allows the animals to run out without disturbance, and the run-out time gives reliable results about the extracting process. a minor systematic difference was found between the automatically and manually measured body length data. fine-tuning the device can potentially overcome systematic differences in the future. however, the standard deviation of this difference was relatively large due to some outlier body size data. these outliers were mostly shorter but also longer than the normal body length values. the reason for these large deviations (> 0.3 mm) might be (1) that the ai could not adapt to recognize the unusual body positions of the collembolan individuals (fig. 3/2.,3/4.). in these cases, the device largely underestimated the body sizes compared to the manual measurement. (2) in two cases, the animals fell into the cover of the blow-off opening, and the machine measured only part of their body (fig. 3/3). finally (3), the animals climbed up the funnel wall, so the device detected them as shorter than the normal body position (fig. 3/1). in the future, these outliers might be corrected by a built-in filter that uses the body length-body width ratio of f. candida, and extreme deviations from normal ratios can be sorted out. finally, the outlier body lengths were sometimes higher than the mean values. although the artificial intelligence follows the movement of the animals and can separate the falling f. candida individuals, in the case of two or more animals falling on top of each other, the ai program could not distinguish them and measured the two specimens as one. the simultaneous fall of several animals might be another reason for misdetection, which the further development of individual identification can solve. this new edapholog device allows us to follow the progress of soil-microarthropods' extraction by time stamps for every detection. there are many other possible experiments with the edapholog, even with several species simultaneously, in which the dynamics of the extraction can also be tested. by further development, the use of edapholog can greatly contribute to determining the species diversity and density of soil-dwelling invertebrates. edapholog is a tool that can also be used in environmental ecology, which can greatly contribute to quick and precise data extraction. conclusion although the applied drought treatments did not cause significant differences between the body sizes of treated f. candida groups, greater differences in drought levels might cause greater changes in body sizes and in species abundance, which might cause local extinction under natural conditions. microarthropods play a significant role in soil carbon sequestration, so their decreasing presence in the soil may increase atmospheric carbon dioxide. the accuracy of the automatic body size estimation was high enough, making it suitable for automatic body size estimations. we measured only a small systematic error between the manual and automatic measurements, which can be corrected by further calibration. acknowledgement the authors are grateful to veronika gergócs and norbert flórián for their help in the work. thanks for bernát zawiasa for programming the automatic body size estimation and the institute for soil sciences (center for agricultural research) for providing the research environment. the experiment was financed by hungarian support grants for life projects (project id nybzk/52/2023). references agatz, a., hammers-wirtz, m., gergs, a., mayer, t., preuss, t.g. 2015. family-portraits for daphnids: scanning living individuals and populations to measure body length. ecotoxicology 24(6), 1385–1394. https://doi.org/10.1007/s10646-0151490-0 aszálymonitoring. 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environmental geography 16 (1–4), 46–54. ecology and evolution 13(12), 2729–2742. https://doi.org/10.1111/2041-210x.14001 szabó, b., bálint, b., balogh, k., mézes, m., seres, a. 2022. changes in soil moisture and temperature modify the toxicity of sodium selenite and sodium selenate for folsomia candida (collembola) willem 1902. applied soil ecology 177, 104543. https://doi.org/10.1016/j.apsoil.2022.104543 wang, y., slotsbo, s., holmstrup, m. 2022. soil dwelling springtails are resilient to extreme drought in soil, but their reproduction is highly sensitive to small decreases in soil water potential. geoderma 421, 115913. https://doi.org/10.1016/ j.geoderma.2022.115913 https://doi.org/10.1111/2041-210x.14001 https://doi.org/10.1016/j.apsoil.2022.104543 https://doi.org/10.1016/%20j.geoderma.2022.115913 https://doi.org/10.1016/%20j.geoderma.2022.115913 introduction materials and methods test animal and materials experimental design automatic detection of soil microarthropods automatic measurement of body length statistical analysis results drought tolerance experiment reproductive success comparison of the manual and automatic measurement methods discussion drought tolerance measurement methods conclusion acknowledgement references akta4 journal of env. geogr. vol. i. no. 1-2. pp. 41-51 changes of cross-sectional morphology and channel capacity during an extreme flood event, lower tisza and maros rivers, hungary sipos, gy.1 – fiala, k.2 – kiss, t.1 1department of physical geography and geoinformatics, university of szeged, h-6722 szeged, egyetem u. 2-6, hungary, gyuri@earth.geo.uszeged.hu, kisstimi@earth.geo.u-szeged.hu 2directorate for environmental protection and water management of the lower tisza district, h-6720 szeged, stefánia 4, hungary, fialak@atikovizig.hu abstract when examining the characteristics of individual floods hungarian researchers primarily investigate hydrological and hydraulic processes, whilst the relation between flood events and morphological changes of the river-bed are widely ignored. the present research quantifies the morphological changes of two cross-sections of the lowland reaches of the river tisza and its tributary, the river maros, during a high magnitude flood which occurred in spring 2000. during the flood several key morphological cross-section variables (mean depth, channel bed elevation, maximum depth, cross-sectional area and channel capacity) were monitored. relationships between these data and daily river stage height series of the flood and specific stream power were determined. results suggest that the identified morphological changes highly affect the channel capacity of the two cross-sections during the flood event. the channel capacity changes (9-10%) were almost identical for both study sites. however, different morphological processes characterised the two cross-sections. we found that morphological parameters depend not only on the actual stream power, but the available amount of sediment for transport, the rate of stage and stream power change. keywords: flood, riverbed morphology, specific stream power, water conducting capacity introduction as a consequence of continuous stage height and discharge monitoring since the end of the 19th century the hydrology of the major hungarian rivers is fairly well known. numerous authors have studied the hydrological characteristics of the floods occurring on the tisza and maros rivers (bogdánfy ö. 1906, károlyi z. 1960a, bezdán m. 1998, 1999, vágás i. 2000, 2001, illés l. et al. 2003). vágás i. (1984) observed on the river tisza that the peak stage heights of floods with similar discharges tend to increase since the beginning of the measurements. in order to explain these changes climatic, hydrological, and land use changes in the catchment were investigated (nováky b. 2000, rakonczai j. 2000, somogyi s. 2000, bodolainé jakus e. 2003, gönczy s. et al. 2004). other studies put a special emphasis on the role of floodplain aggradation (nagy i. et al. 2001, gábris gy. et al. 2002, kiss t. et al. 2002, sándor a. – kiss t. 2006). however, morphological processes (e.g. bank erosion, incision or aggradation) acting in the river channel during floods have rarely been analysed on hungarian rivers, even though these processes also influence flood stages (starosolszky ö. 1956, károlyi z. 1960ab, sipos gy. et al. 2007). at the same time more channel survey and discharge data are available (szlávik l. – szekeres j. 2003), which could further help the analysis of morphological development. it is widely accepted that the increasing bed load transport and intensive dune and bar migration during floods have an effect on cross-sectional area (bogdánfy ö. 1906, németh e. 1954, károlyi z. 1960b). thus, morphological changes may contribute to (i) the characteristic loop-like curve of stage-discharge relationships (németh e. 1954), and (ii) the differences of mean flow velocity during the rising and falling limbs of floods (németh e. 1929, vágás i. 1984). the present study analyses the channel crosssection evolution during an exceptional, high magnitude flood in 2000 at two gauging stations located on the tisza and maros rivers. the aim of the research is to monitor and to quantify morphological changes at each cross-section, and to compare the two rivers with different hydrological characters. the analysis also can help to understand channel changes (channel capacity) during floods, and provide a further explanation for increasing flood levels at the same discharge. study sites the study sites are located on the lowland, sandbedded reaches of the rivers tisza and maros (fig. 1a). the channel cross-sections are at the algyı (tisza river) (fig. 1b) and makó (maros river), (fig. 1c) gauge stations. these sites were chosen because they are located on similar, lowland sections of the studied rivers. the need for comparison is also supported by the fact that both rivers were severely regulated, but gave different answers for human intervention (flood hazard has increased on the tisza, but not on the maros). one reason for this can be that the two rivers show very different discharge and sediment regime, as it is shown in table 1. flood duration is significantly longer on the river tisza (1.5-3 months) than on the maros, being much flashier (1-2 weeks) (török i. 1977, andó l. 2002). the sediment regime of the two rivers is also 42 gy. sipos et al. joeg i/1-2 different. based on the total sediment loads, the tisza transports significantly more suspended sediment. however, the specific suspended sediment load is almost three times more on the maros than on the tisza indicating greater sediment concentrations. in terms of bed load transport the difference between the two study sites is even more important, as both the total and the specific bed load are significantly higher on the river maros. the algyı gauge station is located at a bridge on a straight section of the river tisza between two meanders 191.8 river kilometres (rkm) upstream of the estuary (fig. 1b). the bankfull width at the cross-section is 115 m. based on the full series of measurements (19292000), the mean depth is 12.8 m, maximum depth is 18 m, and the thalweg is usually located in the middle of the cross-section, which is typical of inflectional reaches. the makó gauge station is located 24.6 rkm from the maros estuary at the upstream end of a fairly long, straightened reach of the river (fig. 1c). bankfull width is 112 m, mean depth is 4.8 m. averaging all the avai fig. 1 the location of the studied reaches (a), and the locations of monitored gauge stations near algyı (b) and makó (c table 1 characteristic stage, discharge and sediment load values at the algyı (tisza) and makó (maros) gauge stations. the specific sediment load (t/m3) is sediment load (t/y) divided by mean discharge (m3/s). (source of data: http://www.vizadat.hu and bogárdi 1955, 1971) tisza (algyı) maros (makó) maximum (1976-2000) 983 624 mean (1976-2000) 284 36 minimum (1976-2000) -3 -104 stage height (cm) bankfull (2000) 610 310 maximum (1976-2000) 3 820 2 420 mean (1976-2000) 930 161 minimum (1976-2000) 63 34 discharge (m3/s) bankfull (2000) 2 020 850 suspended load (1971) 18 700 000 8 300 000 sediment load (t/y) bed load (1971) 9 000 28 000 suspended load (1971) 6,3x1011 1,6x1012 specific sediment load** (t/m3) bed load (1971) 3,1x108 5,5x109 joeg i/1-2 changes of cross-sectional morphology and channel capacity during an extreme flood event, lower river tisza and river maros, hungary 43 lable cross-sections (1988-2000), the "average" crosssection displays two troughs near the two banks and an elevation in the middle of the channel (fig. 7). the cross-sections refer to frequent thalweg shifts and thalweg dissection. methods the stage and discharge data were provided by the atikövizig (directorate for environmental protection and water management of the lower tisza district). regular depth measurements, related to discharge monitoring, are similarly made by the atikövizig at the studied gauge stations since 1988. the endpoints of the cross-sections are stable survey-points and their geographic coordinates are determined. in case of the tisza (algyı site), water depth is determined from a bridge at 5 m intervals. on the maros (makó site) the measurements are made along a steel wire at 2 m intervals. measurements are carried out on a monthly basis, except during flood events and extreme low water periods when discharge and water depths are monitored daily. during the selected study period (february 01. 2000 – june 30. 2000) 35 water depth measurements were made on the river tisza at the algyı gauge station, and 28 on the river maros at makó. in order to follow morphological changes, reference water levels were set at both cross-sections. this reference level was bankfull water stage. it is relatively stable, clearly definable and has a geomorphic importance in terms of signing the stage at which the maximum stream power is exerted on unit area of the riverbed. as a consequence, the comparison of morphological changes became possible in between the two cross-sections as well. the following morphological channel variables were calculated and monitored: mean depth [dmean]; maximum depth [dmax], cross-sectional area [a], all measured from the bankfull level, and morphological roughness [r]. roughness was defined as the morphological diversity of the riverbed. its value was calculated as the summed difference between concomitant depth values [d] with the following roughness equation: ∑ = +−= n i ii ddr 0 1 this roughness index is not in relation with those derived from the grain size of riverbed sediments (e.g. starosolszky ö. 1970, fehér f. et al. 1986). it evaluates the channel from the aspect of morphology, and thus it can be identified as form roughness (nikora v. i. et al. 1998, millar r. g. 1999). based on the dataset of stage variation different phases of the flood could be separated (rising stage, peak flow, falling stage). in order to analyse the different phases of the flood from the point of view of the changes in morphological parameters, the parameters were related to the daily rate of stage variation and specific stream power [ω]. specific stream power enabled the comparison of the two rivers in terms of energy conditions during different flood phases. specific stream power was determined according to graf w. h. – altinakar m. s. (1998): ω = qsgρ/w where [q] is discharge (m3/s), [s] is water surface slope (m/m), [g] is gravitational acceleration (m/s2), [ρ] is the summed density of liquid and solid phases (m3/kg), and [w] is water surface width (m). water surface slope was determined on the basis of stages measured at the studied gauge station and the closest station upstream (6 and 10 km). the floodplain component of width and discharge was disregarded, thus the specific stream power of the channel itself was determined. characteristics of study periods in the spring 2000 a long-lasting flood period was detected in the eastern part of the carpathian basin, which could be divided into two main floods. an early spring smaller flood wave was followed by the main flood in may, when simultaneous, long-lasting floods developed on the river tisza and its tributaries, including the river maros (fig. 2). the floods of both rivers were divided into differenat phases (fig. 3-4) based on the direction of stage change. fig. 2 discharge curves of the 2000 flood at the algyı (tisza river) and the makó (maros river) cross-sections (source: hydrological year book, calculated data) 44 gy. sipos et al. joeg i/1-2 fig. 3 hydrograph (solid line) and specific stream power (squares) at the algyı cross-section (tisza). black squares also indicate dates of channel cross-sectional measurements. phases of floods are indicated as 1-7 fig. 4 hydrograph (solid line) and calculated data of specific stream power (squares) at the makó cross-section (maros). black squares also indicate dates of channel cross-sectional measurements. phases of floods are indicated as 1-4 the first, early spring flood crest was reached after a very rapid stage rise on both rivers (tisza: 32 cm/day in average, 39 cm/day maximum; maros: 55 cm/day in average, 139 cm/day maximum). the flood on the river tisza reached its crest earlier (phase 1; fig. 4), on february 18 (algyı: h=587 cm, q=1610 m3/s). on the river maros the highest stage was measured one month later (phase 1-2; fig. 3), on march 16 (makó: h=378 cm, q=345 m3/s) (fig. 3-4). subsequently, a 17-day and an 11-day long intensive stage fall occurred on both rivers (tisza: 23 cm/day; maros: 24 cm/day). along with the increase of discharge and water surface slope the value of specific stream power at the makó gauge station (maros) showed a sudden rise, reaching its maximum during the short peak stage (20 hours) period (ω=15,9 w/m2). during the first, early spring flood no crosssectional measurements were performed at algyı (tisza), thus no specific stream power could be calculated. the second flood wave resulted in significantly higher stages on both rivers, at the algyı gauge station (tisza) even a new record was observed, since the beginning (1842) of the stage measurements. in the case of the tisza the major flood, which started in march and terminated in may can be divided into five phases (phase 3-5; fig. 3). first there was a quick stage rise between the 4 and 21 march (in average 24 cm/day, occasionally 66 cm/day), then an eight day long peak period came. until april 21 another, less intensive rise occurred (in average 14 cm/day, occasionally 32 cm/day). following the flood crest (hmax=983 cm, q=2810 m 3/s) stage fell back to its pre-flood level in 42 days (in average 20 cm/day stage fall). values of the specific stream power changed with stage variations. the maximum value (ω=7,3 w/m2) was reached on april 19, two days before the peak flow arrived (fig. 3). it can be explained by surface slope changes, as the greatest slope is measured before the flood crest. in case of the maros flood the rising limb of the second, major wave can be considered continuous (phase 3, fig. 4). the rate of stage rise was similar to that of the tisza (22 cm/day, occasionally 67 cm/day). the flood crest was reached in 18 days on april 14 (h=499 cm q=1120 m3/s), then it was followed by a relatively quick fall (15 cm/day), the continuity of which was disturbed by only a small late wave (fig. 4). the maximum value of the specific stream power was reached four days before the peak flow period at the end of the rising limb (ω=17,8 w/m2); later it decreased slowly (fig. 4). hydrographs of the two rivers (fig. 3-4) are similar in the number of flood crests; however, peak flow durations were much longer in the case of the tisza than the maros, and the maros stage fall was more rapid (20 cm/day versus 15 cm/day). energy conditions showed greater fluctuations at makó (maros) during the flood, and the maximum value of specific stream power was three times higher than in the case of algyı (tisza). reasons were the significantly greater water surface slope and suspended load concentration apparent on the maros. another difference between the two rivers was that the maximum value of specific stream power occurred 2 days and 4 days before the peak flow of the main flood wave at algyı and makó, respectively (fig. 3-4). morphological changes at the algyi̇ cross-section (tisza) first rising limb (phase 1) and second rising limb (phase 3) during the first flood (february 1 – march 4) only one rising limb discharge measurement was performed, joeg i/1-2 changes of cross-sectional morphology and channel capacity during an extreme flood event, lower river tisza and river maros, hungary 45 thus the exact description of morphological changes was not possible. however, the water-depth data obtained on february 7 could be compared to those measured during the rising limb of the main flood wave (fig. 6), since the cross-section was recorded in both cases among similar stage and discharge conditions. minor differences were experienced in terms of maximum depth (dmax=18.2 m, and dmax=18.5 m). the roughness index increased slightly (r=28.7 and r=29.2; see fig. 6), as the specific stream power was also greater in phase 3 (february 8: 1.6 w/m2, march 9: 2.0 w/m2; see fig. 3). however, in both cases the energy of the system increased suddenly due to intensive stage rise (36 cm/day and 30 cm/day). second rising limb (phase 3) and first peak flow period (phase 4) during the first part of the main flood wave (march 4 to march 21) only two cross-sectional surveys were made (fig. 3), one during the intensive rising limb and another during the 8-day long peak flow period. rising limb stage increase rate was 30 cm/day in average, with a maximum between march 12 and march 18 (44-66 cm/day). at that time relatively high maximum depth (dmax=18.5 m) and roughness index (r=29.2) characterised the channel (fig. 6). during the peak flow period (march 22-30) both maximum depth (dmax=18.0 m) and roughness (r=28.5) dropped, although specific stream power increased in the meantime from ω=2.0 w/m2 to ω=3.5 w/m2. thus, we suggest that the morphological difference between the rising limb and peak flow channel can be independent from changes in the specific stream power. third rising limb (phase 5) following a few days of stability water level started to rise again between march 31 and april 19 in the beginning at a rate of 12 cm/day but from april 10 at a rate of 30 cm/day. during this time mean and maximum fig. 5 (a) monitored cross-channel sections (28) during the 2000 flood (february 8 – may 16) on the tisza at algyı. (b) three characteristic cross-sections taken at different phases of the flood fig. 6 variation of morphological parameters during the 2000 flood at algyı (tisza). 1-7 indicates the different phases of the studied period 46 gy. sipos et al. joeg i/1-2 depths were increasing, however in a highly fluctuating manner (fig. 6). the most intensive erosional activity can be related to this period, as the greatest mean and maximum depth values were measured on april 19 (dmean= 13.1 m; dmax=19.1 m). also, at this phase the roughness index of the riverbed reached its maximum (r=29.9 – 31.3) as dunes and dune sequences developed (fig. 5b). the most probable reason for the river incision and intensive transportation is the greatest value of specific stream power during the flood (on april 19: ω=7.3 w/m2). note, that the maximum of ω was experienced two days before the peak stage was reached, its reasons are also in relations with the watersurface slope increase before the flood crest. second peak flow period (phase 6) during the peak of the main flood wave (hmax=983 cm) the mean and maximum depth of the channel (dmean=12.6 m and dmax=18.2 m) decreased by 10% (fig. 6). in the background the decrease of stream power (from ω=6.9 w/m2 to ω=6.5 w/m2) is the aggradation within the channel (fig. 3 and fig. 5b). as a result, the area of the cross-section decreased and reached its minimum value (a=1585.4 m2). in accordance to the aggradation the lowest roughness index was also experienced at this time (r=26.5 on april 22) meaning that r decreased by 10% compared to rising limb maximum values. these changes suggest that the intensity of sediment transport, initiated mainly during the rising limb, decreased significantly in the peak phase (fig. 5b). second falling limb (phase 7) subsequent to the 3-day long peak flow period starting on april 21, the water level started to fall at an increasing rate till may 14. in the first period of stage fall (7 cm/day) parallel with the decrease of specific stream power (fig. 3) depth values dropped (dmean=12.6 m; dmax= 17.6 m), i.e. the channel aggraded. nevertheless, when stage fall became more intensive and reached values of 12 cm/day, erosion occurred again (fig. 5b and fig. 6). the process of channel incision was continuous (dmean=13.0 m; dmax =19.1); therefore, crosssection area increased and reached its maximum (a=1742.6 m2). roughness also increased (r=30.0), higher values were measured only during the most intensively rising days (fig. 6). at the same time, the value of the specific stream power significantly decreased (from ω=6.4 w/m2 to ω=5.5 w/m2). morphological changes at the makó cross-section (maros) first rising limb (phase 1) in the rising phase of the first flood wave (march 10-16) depth and roughness values increased significantly: mean depth by 11 cm (5%), maximum depth by 84 cm (21%) and the roughness index by nearly 50% (from r=13.4 to r=19.7) (fig. 8). overall, the channel deepened, while the riverbed was characterised by several half a meter-, meter-high forms, which can be interpreted as dunes developing due to the increase of stream power (fig. 7b). in the meantime, by the disappearing of the right bank trough, no permanent thalweg could be identified in the channel. this phase occurred while a large quantity of bed sediment was entrained and started to move in the channel as a result of sudden specific stream power increase (from ω=3.9 w/m2 to ω=15.9 w/m2) (fig 7b). first falling limb (phase 2) right after the peak of the flood (march 16) as water surface slope and specific stream power decreased the fig. 7 (a) monitored cross-channel sections (22) during the 2000 flood (february 8-june 6) on the maros at makó. (b) three characteristic cross-sections taken at different phases of the flood joeg i/1-2 changes of cross-sectional morphology and channel capacity during an extreme flood event, lower river tisza and river maros, hungary 47 values of morphological indices dropped back suddenly. in 3 days mean depth and maximum depth decreased by 16 cm (6%) and 82 cm (21%), respectively. thus, depth practically returned to pre-flood levels, unlike the roughness index, which did not reach its former value, and decreased from r=19.7 to only r=15.3 (fig. 8). the slight decrease of roughness was due to the development of a positive form in the middle of the channel (fig 7a). based on one cross-section, it is not possible to describe the form; however, it seems as if the profile of a mid channel bar, formed from dunes overrunning each other due to the decrease of stream power (nikora v. i. et al. 1997), can be observed. second rising limb (phase 3) during the first part of main flood wave stage rise (march 27-april 7) no measurements were made. the april 7 cross-section shows that the width of the mid channel accumulation increased up to 70-80 m. in the meantime, a small trough appeared at its axis; thus, roughness increased significantly again (r=17.8) (fig. 8). on the next day (april 8) the erosion of the trough was more expressed; in this way, actually, a third thalweg developed in the channel. in the following days, mean and maximum depth and roughness were fluctuating intensively (fig. 7a and fig. 8). consequently, from a morphological aspect this phase of the flood can be considered as the phase of significant sediment relocation in the form of dunes and bars. in terms of the second flood wave the greatest roughness (r=19.0) mean and maximum depth (dmean=4.58 m, dmax=6.12 m) values were measured on april 13, one day before the peak stage (fig. 7b and fig. 8). two important observations were made in connection with the above. firstly, the greatest morphological diversity and the maximum of specific stream power (april 10: r=16.1 m, dmean=4.55 m, dmax=5.62 m) did not coincide (compare fig. 4 and fig. 8), and morphological indices were the highest when the value of ω already started to decrease (from 17.9 w/m2 to 16.7 w/m2). secondly, even at this time depth values and roughness were significantly smaller than those experienced during the first flood wave, although at that time specific stream power was lower. therefore, it is not at all obvious that the higher the specific stream power is the greater morphological diversity and cross-sectional area can be expected. another morphologically important pheno-menon was that during the rising limb of the second flood wave (april 7-april 14) the base level of the riverbed was 2030, in some cases 50 cm higher than during the first flood. thus, the second flood wave did not scour the channel bed, but probably it transported the previously relocated sediment in the form of dunes and bars (fig. 5b). we suggest that, the gentler rise of stage during the second wave and the high volume of already entrained sediment from the upper sections explain the shallower riverbed. second falling limb (phase 4) the very short peak flow period (april 14) was followed by a rapid stage fall, during which mean depth decreased by 9 cm (4%) in 5 days; thus, in accordance with decreasing stream power the bed was filled up. then due to a slight stage rise within the falling limb depth and roughness values increased a little (fig. 8). however, on the basis of the april 23 and 29 crosssections, later the bed became almost even, and roughness dropped to 71% of the maximum value. from a fig. 8 variation of morphological parameters during the 2000 flood at makó (maros). 1-4 indicate the different phases of the study period 48 gy. sipos et al. joeg i/1-2 morphological aspect this is in connection with the disappearance of separate thalwegs (fig. 5b). nevertheless, depth values stayed almost the same during the late part of the falling limb. finally, by the beginning of may a slight left bank accumulation appeared (side bar) and the thalweg returned to the right bank. if cross-sections taken right before and right after the 2000 spring flood are compared, then mean channel depth decreased by 18 cm (8%), maximum depth hardly changed (6 cm, 2%), and form roughness was very close to its original value (r=13.4 m before and r=14.1 m after). changes in channel capacity the above-described morphological parameters also define the actual channel capacity of the two studied cross-sections. at the algyı gauge station (tisza) bankfull cross-sectional area significantly increased during stage rise (phase 1, 3 and 5; fig. 9). in these phases the cross-section area and stream power increased simultaneously. however, the tendency of the area increase was characterised by significant variations. in some occasions a 6-7 % daily change was detected in crosssectional area during the main flood wave. these processes indicate intensive morphological changes in the channel. during the peak flow period depth values and the diversity of the riverbed significantly fell back, resulting the decrease of cross-sectional area and thus water conducting capacity (march 18 rising limb: a=1711 m2; march 18, peak stage: a=1631 m2). minimum conductivity values occurred during maximum stage and discharge (april 21, peak stage: a=1585 m2), when water surface slope and concomitant stream power decrease were apparent. it was also observed that the same values of stream power resulted in lower channel capacity during the peak flow period then during the rising limb (e.g. april 17, rising limb: ω=6.8 w/m2, a=1715 m2; while april 21 peak flow: ω=6.8 w/m2, a=1585 m2) (fig. 9). at the algyı gauge station of the tisza during stage fall depth and roughness increase were experienced. this resulted in a larger bankfull cross-sectional area and an increased water conducting capacity (april 25: a=1675 m2, may 5: a=1714m2). when stage fall became more intensive a significant fluctuation was observed; however, daily changes did not exceed 3%, representing continuous morpho-logical development, though less intensive than at the rising limb. in the meantime, along with the slow decline of discharge and slope the value of specific stream power also decreased (april 24: ω=6.5 w/m2; may 4: ω=5.5 w/m2) (fig. 3). consequently, a completely different relation was observed between stream power and conducting capacity than during the rising limb or at peak discharges (fig. 9). in terms of the makó cross-section (maros) the 2000 flood resulted in some similar situations. at the rising limb of the first flood wave similarly to the rising limb of the tisza main flood wave bankfull crosssectional area increased, however its degree was only 2%. the maximum channel capacity during the entire flood occurred at the peak of the first wave (march 16, short peak period: a=565 m2) (fig. 10). by the start of bar migration during the next rising limb, in spite of increased discharge and stream power bankfull area was decreasing. when the river reached its maximum specific stream power during the main flood wave (ω=17.8 w/m2) cross-sectional area was 5% lower than in a similar period of the first wave (12.9 w/m2). this contradicts the relationships experienced at algyı, though there the work of the first flood wave could not be assessed precisely. following the short peak period of the maros (20 fig. 9 relative change of the bankfull cross-sectional area during the 2000 flood at algyı, tisza. value of the first measurement was taken as 100% joeg i/1-2 changes of cross-sectional morphology and channel capacity during an extreme flood event, lower river tisza and river maros, hungary 49 hours) as stream power and roughness decreased no significant variation was detected in channel capacity (fig. 10). at the end of the falling limb the bankfull area of the cross-section (a=533 m2) was almost identical to the value observed during peak flow (april 19: a=530 m2); however, by this time ω dropped to 1.68 w/m2 which was only one tenth of the peak stage value. consequently, morphological processes during the falling limb were different than at the algyı cross-section. the possible reason for this is that the river due to the sudden loss of stream power was not able to transport further the bed load pulse initiated by higher energy periods. according to sipos gy. (2007), bedforms created by flood waves remain stable in the channel and for post-flood low waters it takes a relatively long time to restore the original bed state within the sand bedded river maros. the difference of the maximum and minimum cross-sectional area measured during the entire spring flood was 9.1% (∆a=157 m2) on the tisza and 9.6% (∆a=54 m2) on the maros. thus, total variation was very similar (figs. 9-10). in terms of maximum daily change, area difference was greater at algyı (6.9%) than at makó (5.1%). nevertheless, variations during one day are not possible to determine at the present measurement frequency. still, it seems well supported that relative variations in channel capacity were very similar at the two cross-section during the 2000 flood, despite of the fact that the maximum of specific stream power was 2.6 times greater in case of the maros, and the standard deviation of these data was 6.2 at makó, while it was only 1.8 at algyı. the suggested reason why higher and more diverse stream power conditions did not cause greater morphological changes on the maros is the remarkable volume of bed load (table 1), which may buffer the energy variations of the river. however, the precise role of bed load in this respect is not possible to assess in detail because of the few number of sediment discharge measurements. conclusions at both the algyı cross-section of the tisza and the makó cross-section of the maros significant morphological changes were observed during the 2000 flood. these changes greatly influence the channel capacity of the channel. morphological development was compared to variations in specific stream power and the rate of stage rise or fall. the way and degree of changes were different at the two sites. on the river tisza at algyı significant variations were experienced in depth and roughness during the rising limb, depending on the value of specific stream power and the intensity of stage rise. the overall process at this phase was the lowering of the bed level, thus the increase of channel capacity. during the days of the peak flow period, along with the sharp decrease of stream power the cross-sectional area decreased. this can be explained by the reduction of bed load transport and subsequent in channel aggradation. nevertheless, at the falling limb of the flood in spite of the definite decrease of stream power depth increased again, and the area of the bankfull cross-section grew. in order to explain this controversy, further investigations are necessary. on the river maros, at makó erosional activity was dominant only in the rising limb of the first flood wave. the greatest channel capacity was detected at this phase. contrary to the processes at algyı, during the main flood wave a continuous bed level rise was detected at makó, even in case of periods with the highest energy levels. during the abrupt falling limb of the hydrograph the morphology of the channel settled, though depth fig. 10 relative change of the bankfull cross-sectional area during the 2000 flood at makó (river maros). value of the first measurement was taken as 100% 50 gy. sipos et al. joeg i/1-2 values and bankfull cross-sectional area changed insignificantly. both the total and the daily variation of conducting capacity was similar at the two gauge stations, meaning a 9-10% difference between the maximum and the minimum cross-sectional area and a maximum 5-7% daily change. similarity is striking considering that variation of specific stream power were much significant in the case of the maros than on the tisza (makó ωmax/ωmin=10.6; algyı ωmax/ωmin=4.6). the paper proved the intensive cross-sectional changes during a flood, the processes outlined above show obviously a natural fluctuation. therefore, based on only one flood it would not be sensible to generalise their role in the long term increase of flood levels. however, based on our present research, it is obvious that both in terms of the tisza and the maros the maximum of channel capacity usually will not coincide with maximum discharge and stage or maximum stream power. therefore, morphological processes related to bed load transport can have a significant influence on peak stages and flood levels. though earlier studies proved that the increasing bed load transport and intensive dune and bar migration during floods have an effect on crosssectional area (bogdánfy ö. 1906, németh e. 1954, károlyi z. 1960b), but could not calculate changes in detail. our study proved that before the flood crest the specific stream power reaches its maximum, causing intensive scouring and bedload transport. however, at the period of flood crest the specific stream power is already decreased, therefore despite of former beliefs aggradation can truly overwhelm erosion at this phase, resulting significant channel capacity decrease. earlier studies also over generalized the role of falling stages, supposing intensive aggradation; however, we proved that slow scouring can also occur in this period. acknowledgements we wish to thank the atikövizig for providing the data of crosssectional measurement. we are also grateful for the precious advice received on the may 2007 budapest meeting of the hungarian hydrological society. our work was financially supported by the otka 62200 research grant. references andó m. 2002. a tisza vízrendszer hidrogeográfiája (the hydrogeography of the tisza catchment). university of szeged 143 p. bezdán m. 1998. kölcsönhatások a tisza-vízgyőjtı folyóin hidrológiai közlöny 78/4: 247-249 bezdán m. 1999. a tisza balparti mellékfolyóinak hatása az árhullámokra. hidrológiai közlöny 79/2: 89-99 bodolainé jakus e. 2003. az 1998. évi ıszi tiszai és más nagy árhullámok idıjárási okairól. vízügyi közlemények 85, special issue i: 21-33 bogárdi j. 1955. a hordalékmozgás elmélete. budapest: akadémiai kiadó. 543 p. bogárdi j. 1971. vízfolyások hordalékszállítása. budapest: akadémiai kiadó. 366 p. bogdánfy ö. 1906. a természetes vízfolyások hidraulikája. budapest: franklin társulat. 250 p. fehér f. – horváth j. – ondruss l. 1986. területi vízrendezés. budapest: mőszaki könyvkiadó. 146 p. fiala k. – kiss t. 2005. a középvízi meder változásai az 1890es évektıl az alsó-tiszán. hidrológiai közlöny 85/3: 60-68 fiala k. – sipos gy. – kiss t. – lázár m. 2007. morfológiai változások és a vízvezetı képesség a tisza algyıi és a maros makói szelvényében a 2000. évi árvíz kapcsán. hidrológiai közlöny 87/5: 37-46 gábris gy. – telbisz t. – nagy b. – belardinelli e. 2002 a tiszai hullámtér feltöltıdésének kérdése és az üledékképzıdés geomorfológiai alapjai. vízügyi közlemények 84/3: 305-322 gönczy s. – molnár j. – szabó g. – sándor a. 2004. az erdıirtások hatása az árvízi vízhozamokra a felsı-tisza kárpátaljai mellékfolyóin. földtani kutatás 41/3-4: 52-56 graf w. h. – altinakar m. s. 1998. fluvial hydraulics, flow and transport processes in channels of simple geometry. chichester: wiley. 506 p. illés l. – konecsny k. – kovács s. – szlávik l. 2003. az 1998. novemberi árhullám hidrológiája. vízügyi közlemények 85, special issue 1: 47-76 károlyi z. 1960a. a tisza mederváltozásai – különös tekintettel az árvédelemre. tanulmányok és kutatási eredmények 8. budapest: vituki. 350 p. károlyi z. 1960b. zátonyvándorlás és gázlóalakulás különös tekintettel a magyar felsı-dunára. hidrológiai közlöny 40/5: 349-358 kiss t. – sipos gy. – fiala k. 2002. recens üledékfelhalmozódás sebességének vizsgálata az alsó-tiszán. vízügyi közlemények 84/3: 456-472 millar r. g. 1999. grain and form resistance in gravel bed rivers. journal of hydraulical research 37: 303-312 nagy i. – schweitzer f. – alföldi l. 2001. a hullámtéri hordaléklerakódás (övzátony). vízügyi közlemények 83/4: 539-564 németh e. 1929. vízmérceállások és vízmennyiségek összefüggése. vízügyi közlemények 11/2: 41-66 németh e. 1954. hidrológia és hidrometria. budapest: tankönyvkiadó. 458 p. nikora v. i. – sukhodolov a. n. – rowinski p. m. 1997. statistical sand wave dynamics in one-directional water flows. journal of fluid mechanics 351: 17-39 nováky b. 2000. az éghajlatváltozás vízgazdálkodási hatásai. vízügyi közlemények 82/3-4: 418-448 rakonczai j. 2000. a környezet hidrogeográfiai összefüggései az alföldön. in: pálfai i. 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(ed.) 1977. a maros folyó 0–51,33 fkm közötti szakaszának szabályozási terve. szeged: alsótiszavidéki vízügyi igazgatóság. 119 p. vágás i. 1984. az árvízi hurokgörbe. hidrológiai közlöny 64/6: 333-341 vágás i. 2000. a tisza és árvizei. hidrológiai tájékoztató 40/1: 45-50 vágás i. 2001. az ezredforduló árhullámai a tiszán. magyar tudomány 48/8: 958-866 risk management as a basis for integrated water cycle management in kazakhstan journal of environmental geography journal of environmental geography 9 (3–4), 33–42. doi: 10.1515/jengeo-2016-0010 issn: 2060-467x risk management as a basis for integrated water cycle management in kazakhstan burghard meyer1*, lian lundy2, john watt2, iskandar abdullaev3, jose e. capilla roma4 1leipzig university, institute of geography, johannisalle 19a, 04103 leipzig, germany 2middlesex university, department of natural sciences, the burroughs, hendon, london nw4 4bt, uk 3carec, regional environmental centre for central asia, 40 orbita 1, almaty, 050043, republic of kazakhstan 4technical university of valencia, research institute of water and environmental eng. camino de vera, s/n, 46022 valencia, spain *corresponding author, e-mail: e-mail: burghard.meyer@olanis.de research article, received 30 september 2016, accepted 15 november 2016 abstract integrated water cycle management (iwcm) aims to bring together a diversity of social, environmental, technological and economic aspects to implement sustainable water and land management systems. this paper investigates the challenges and opportunities facing kazakhstan as it its efforts to move towards a more sustainable approach to managing its finite and highly stressed water resources. the use of a strategic-level risk governance framework to support a multi-disciplinary kazakh-eu consortium in working collaboratively towards enhancing capacity and capability to address identified challenges is described. with a clear focus on addressing capacity building needs, a strong emphasis is placed on developing taught integrated water cycle management programmes through communication, stakeholder engagement and policy development including appropriate tools for managing the water issues including hydraulic models, gis-based systems and scenario developments. conclusions on the benefits of implementing an eu-style water framework directive for central asia based on a risk management approach in kazakhstan are formulated. keywords: risk management, capacity building, water management, stakeholder engagement introduction kazakhstan is facing important challenges in water resource management from a variety of perspectives, including climate change and melting glaciers (salnikov et al., 2011; smith et al., 2005; chen et al., 2013) over usage of river water resources and groundwater systems for irrigation (dostay, 2012), water pollution by industry and agriculture, and increasing water consumption (qadier et al., 2009). as a result, ecological crises including the drying out of large terminal lakes such as aral lake and, more recently, balkhash lake are reported (zavialov, 2005; turzunov et al., 1997; dostay, 2009). figure 1 shows the main kazakh river catchments, with seven of the eight river catchments identified as being transboundary and thus requiring the establishment of an international water management agreement to peacefully address water distribution conflicts which have been reported (wegerich, 2008). integrated water cycle management (iwcm is a term used in kazakhstan, which is synonymous with integrated water resource management) aims to bring together a diversity of social, environmental, technological and economic aspects to implement sustainable water and land management systems (global water partnership, gwp, 2010). it is widely promoted as international best practice with regard to water resources planning to meet the needs of both current and future generations (e.g. bunting, 2009; eu wfd, 2000; meyer et al., 2014). the central concept is the development and application of objectives in the form of regional and national catchmentbased goals for water management based on each catchment’s natural conditions and water usage patterns. it includes the development of knowledge about ground and surface water quality and quantity, evaluation of water resource policy over a long-term perspective, implementation of plans and actions that have been developed collaboratively by all water users to address problems identified, and the on-going monitoring and evaluation of management processes including the development of simulation models and decision support systems as supporting tools for iwcm (meyer et al., 2014). any implementation of iwcm also includes the protection of the environment by avoiding overexploitation and/or the deterioration of water resources. it requires the development and modernization of institutional structures, methods, legislation and norms including a range of management skills for building capability, capacity and impact in iwcm and working in partnerships. the need to strengthen partnerships between business, regulatory and academic sectors at a national and international level was identified by the kazakh govern34 meyer et al. (2016) ment, with the areas of environmental protection and water management recognised as priority areas requiring action (nazarbayev, 2010). it is within this context that the nurturing of a collaborative cross-sector approach to developing capability and capacity of kazakh graduates in the field of iwcm was the specific challenge targeted by the eu-tempus funded project i-web (integrating water cycle management: capability, capacity and impact in education and business). in addition to its recognition at a national level, kazakh members of i-web were able to further clarify the scale and impact of the major water resource issues currently impacting kazakhstan, demonstrating recognition of its importance at a local and subregional level. these include increasing levels of water consumption by agriculture, industry (especially the gas and oil industries) and urban areas. for example, whilst modernisation of agriculture is strongly encouraged, it is often linked to increasing water consumption. this is leading to reduction in water levels in both surface and groundwater bodies, the most notable example of which is the aral sea (kostianoy and kosarev, 2010; micklin et al., 2014). increasing demand for water resources within kazakhstan is driven by intensifications of agriculture irrigation, industrialisation and urbanisation. together with the transboundary nature of the majority of its river basins, the need for iwcm plans to balance demands on water resources across economic sectors but also across national boundaries is clear. a further crucial aspect is the need to mitigate the impacts of climate change (current scenarios indicate continuing falling levels of precipitation and glacier run-off with the latter imparticular a key source of drinking water supply within almaty (the largest city in kazakhstan). water pollution is also a major national concern, with water quality in many of its surface and ground waters identified as ‘unsatisfactory’. discharges of untreated effluents from chemical industries and petroleum processing are identified as principal sources with devastating environmental impacts reported (lundy, 2014). a common issue in managing environmental resources at a national or regional level is that it requires inputs from a wide range of stakeholders, each with very different capabilities, agendas, mandates and resources. it also requires an evidence–based assessment of the risks associated with adopting any changes in practice proposed, in association with an assessment of the risks of any ’business as usual’ scenario. the complexity of implementing such legislative requirements within and across national boundaries and sectors requires a strategic level risk management approach that utilises the best scientific and technical evidence to prioritise sustainable decisions but also has the flexibility to respond meaningfully to variations in stakeholder perceptions of what is acceptable or tolerable (ecologic institute and seri, 2010). as a contribution to addressing this ‘wicked problem’ of water management in a kazakh context, this paper, maps a strategic risk management approach to developing management capacity. it identifies key methodologies and supporting tools for assisting in the implementation of iwcm and discusses the current status of transboundary basins of kazakhstan and its neighbours. finally conclusions on the benefits of implementing a water framework directive for central asia based on a risk management approach in kazakhstan are developed. fig. 1 map of main river basins and rivers in kazakhstan (water resources committee of the ministry of agriculture of the republic of kazakhstan, anonymous, 2004; map after duskayev & minzhanova 2014, changed) risk management as a basis for integrated water cycle management in kazakhstan 35 study areacurrent status of transboundary basins of kazakhstan and its neighbours water resources are a key for the sustainable economic development of central asian states, with kazakhstan being an exceptionally transboundarydependent state. almost all sectors of the economy in these countries are water dependent, requiring huge amounts of water for development. most of the water resources in the region are transboundary, formed and flowing in from the territory of neighbouring states. almost 60% of water resources of the country are transboundary and kazakhstan is downstream almost in all transboundary basins (table 1). the transboundary water management became a uniquely important aspect of water management in kazakhstan after the collapse of soviet union. table 1 transboundary basins of kazakhstan (see also fig. 1) name of the river catchment area (km2) riparian states irtish 1.643.000 kazakhstan, russian federation, people republic of china tobol 426.000 kazakhstan, russian federation ural 237.000 kazakhstan, russian federation syr darya 219.000 kazakhstan, kyrgyzstan, tajikistan, uzbekistan ishim 177.000 kazakhstan, russian federation ili 140.000 kazakhstan, people republic of china shu 67.500 kazakhstan, kyrgyzstan talas 52.700 kazakhstan, kyrgyzstan other smaller transboundary catchments (not shown in fig. 1) are the big uzen (14.300 km²); the small uzen (13.200 km²) and the burla (12.800 km²) of kazakhstan and russian federation; the aspara catchment (1.210 km²) of kazakhstan and kyrgyzstan and the ugam catchment (870 km²) of kazakhstan and uzbekistan. with russia (ural river basin and others), kazakhstan has agreed “least problematic” relations on transboundary river systems, enforcing the soviet era agreements through water commissions. the abundance of water, resources and a less dry climate made it possible to continue the agreements between kazakhstan and russia made within soviet times (table 2). however, water quality is a current concern and measures to improve the environmental situation in both in the urals and siberia are planned between two countries. being part of eurasian economic union, the two countries have a strong legislative basis for water cooperation (abdullaev and rakhmatullaev, 2013). china, on the other hand, is a major problematic riparian state for kazakhstan. although having major economic interests in kazakhstan, china has made no efforts to improve water cooperation. despite having soviet era agreements in force with china, no technical or institutional enforcement mechanisms are in place to monitor their implementation. kazakhstan has transboundary rivers flowing in from china, russia, uzbekistan, kyrgyzstan and flowing out to the same neighbouring states (table 1). two examples from central asia show different options of transboundary water cooperation where kazakhstan is involved. in both cases, kazakhstan is a downstream country but has applied different approaches in order to receive its water shares from the transboundary rivers. former soviet central asian states have been using water resources of the two largest rivers and many smaller ones since historical times (abdullaev and rakhmatullaev, 2013). the central asian neighbours of kazakhstan are linked with kazakhstan through syr darya river, which supplies water southern part of kazakhstan. around 700,000 ha land and around 1 million people depend from the water of syr darya river. soviet era water agreements and regulations in central asia were arranged and monitored by moscow. the centrally administered and financed water management system has been built to enforce the water agreements among central asia states (then soviet republics). however, frequent water related disputes emerged even in the soviet period, which was arbitrated by the central ministry of water and amelioration of the ussr. the soviet era water agreeme nts were regulated by “normative” documents decrees of cabinet of ministries, assigning water shares to the production system and not to the specific country (state), although national states then translated these allocations into water sharing percentages. although, national states (republics) did not openly contest decisions of the centre, in most of the cases arrangements were made in order to sustain own water shares. therefore, in the mid-1980’s the soviet government felt pressure from the national states and prepared new basin plans for both rivers of the region and launched new institutions river basin organizations (bvo’s) for syr darya and amu darya. these were two serious interventions focused on de -centralizing the transboundary water management in central asia. basin plans clearly predicted development scale and pressure on the river systems of the region and described measures to be implemented in order to balance water situation in the region, including the balancing of the aral sea levels. the basin plan included watersharing percentages among the riparian states. moreover, the plan proposed measures on improving water efficiency in both basins for the long-term. the plan was a part of the centralized, top-down principles of water (natural) resources management in the soviet union. after the collapse of the soviet union, newly emerged central asian countries agreed to keep this system unchanged and signed an agreement in 1992 (abdullaev and rakhmatullaev, 2013). since then, countries of the region have made a few attempts to replace the old soviet water agreement with new one, either for the region as a whole or each for river basin. however, these attempts have not achieved any success. the water allocation in the region is set up through bi-annual meetings of interstate coordination 36 meyer et al. (2016) water commission (icwc), which consists of water ministers of the central asian states. kazakhstan, represented by the deputy minister of agriculture in the commission, receives its shares for syr darya in the meeting of this body. the decisions are made based on water allocation percentage of the flow and water availability forecasts for the given season (6 month). this agreement retains internationally known historical rights principles. however, currently upstream countries, kyrgyzstan and tajikistan, are not happy and are contesting this agreement. the need for energy and abundance of the water resources formed in their territories are arguments used by the two upstream countries to change the pattern of the water use more towards energy generation (abdullaev and atabaeva, 2012; wegerich, 2013). table 2 transboundary river agreements of kazakhstan title of the agreement place and date of signing the agreement agreed bodies and countries focus of the agreement statement of heads of water economy organizations of central asian republics and kazakhstan 10-12 october 1991 meeting in tashkent state committee on water resources of kazakhs ssr, ministry of water resources of kyrgyzstan, ministry of water resources of tajikistan, ministry of water resources of uzbekistan, ministry of water resources of turkmen ssr lack of water resources, ecological tension in aral sea basin http://icwc-aral.uz/statute2 statement between republic of kazakhstan, kyrgyz republic, republic of uzbekistan, republic of tajikistan and turkmenistan on cooperation in the fields of joint management, using and protection of water resources of intergovernmental sources almaty, 18th of february, 1992 republic of kazakhstan, kyrgyz republic, republic of uzbekistan, republic of tajikistan and turkmenistan regulation, protection of water resources, water supply, irrigation related to all transboundary watersheds and lakes agreement between government of russian federation and government of republic of kazakhstan on joint use and protection of transboundary water bodies (and protocol decision on prolongation of the agreement) orenburg, 27th of august, 1992 (pavlodar, 26th of june, 1997) republic of kazakhstan, russian federation protection of water resources, water supply, irrigation, floods, regulation; related to all surface and ground water resources, including transboundary rivers such as ishim, irtish, ural, tobol and volga http://base.spinform.ru/show_doc.f wx?rgn=31129 statement on joint actions to address the problems of aral sea basin and aral sea region, ecological recovery and providing of socio-economic development of the aral sea region kyzyl orda, 26th of march, 1993 republic of kazakhstan, kyrgyz republic, republic of uzbekistan, republic of tajikistan and turkmenistan problems of aral sea basin the inter-state council on aral sea basin problems and its commission has been established http://online.zakon.kz/document/?doc_id=1 045205 statement between republic of kazakhstan and people’s republic of china on kazakhchinese state border almaty,26th of april, 1994 republic of kazakhstan, people’s republic of china identification of location of boundary watersheds, middle of boundary rivers or its main streams, belonging of islands on boundary rivers http://online.zakon.kz/document/?doc_id=1 016993 statement on using of fuel-power and water resources, construction and maintenance of gas pipe line in central asian region tashkent, 5th of april, 1996 government of republic of kazakhstan, government of kyrgyz republic, government of republic of uzbekistan effective using of the hydro resources of syr darya river for irrigational purposes. regulation of working practices of naryn – syr darya cascade of water reservoirs risk management as a basis for integrated water cycle management in kazakhstan 37 kazakhstan has been facing the consequences of the change of water use in the syr darya basin, having floods in winter and water shortages in summer due to the energy generation regime in the river. in order to reduce negative impacts of such changes, kazakhstan has promoted regional energy trade and tried to promote energy exchange with kyrgyzstan and other riparian states. this was a short-lived strategy and only worked for a short time. then kazakhstan took a unilateral approach and built counter-regulations for capturing the water in winter, and strengthened the river bed of the syr darya within its territory. in order to enhance its water security in summer kazakhstan has worked out bi-lateral and mostly informal agreements with kyrgyzstan and uzbekistan. kazakhstan has also developed a different approach utilising exemplary agreements with kyrgyzstan on the chu-talas basin (abdullaev and atabaeva, 2012). in this smaller basin, two sides agreed to work out the agreement on joint management and maintenance of the water infrastructure, which are transboundary. kazakhstan, being the downstream country, has put funds for rehabilitation and maintenance of water infrastructure located in kyrgyzstan. the joint basin organization has been set up by two sides in order to institutionalize the water cooperation. in spite of existing legal and institutional instruments for transboundary cooperation kazakhstan is facing a serious risk on water security. moreover, current setting of transboundary system does not respond to environmental and water quality issues, mainly concentrating only quantity aspects. therefore, inclusion of major stakeholders, namely local – riparian communities into the process of transboundary cooperation will reduce the risk of failure. application of more integrative and inter-sectoral principles would help to include issues of water quality and environmental maintenance into the transboundary negotiations. methodology a scoping study and the creation of a project advisory board to facilitate the development of a common understanding of current working practices and emerging challenges was undertaken for clarification of the major risks with regard to water cycle management. representatives of kazakh academic, practice, policy and student organisations were interviewed to identify current working practices and emerging challenges. the results of this process are detailed in (nireas, 2013) and were used to identify and frame iwcm needs from multiple perspectives. building on the initial assessment, the concept of risk governance (irgc, 2005; renn, 2008; renn and walker, 2008) was identified as a useful framework to link identified strategic and applied components together in a manner that integrated the various functions and showed the relationship between them. watt (2014a) discusses the origin of such approaches and introduces the first major feature that can be used to begin to understand the relationship between the roles of different actors (stakeholders). this reflects a development that emerged in the usa in the 1980s (nas, 1983) that: “regulatory agencies should take steps to establish and maintain a clear conceptual distinction between assessment of risks and the consideration of risk management alternatives; that is, the scientific findings and policy judgments embodied in risk assessments should be explicitly distinguished from the political, economic, and technical considerations that influence the design and choice of regulatory strategies”. in this context, risk governance can be presented as a conversation between two ‘sides’ (risk management and risk assessment), which facilitates evaluation of the functions of those responsible for any given task. policy makers and regulators can be presented as general managers undertaking a risk management function, which may require evidence from scientists and engineers, who are specialists. results and discussion the first challenge identified during the interviewing of stakeholders was the need to support stakeholders in developing a strategic vision – a way of looking at the iwcm challenges faced from the top down that would support recognition of how the various components/activities of stakeholders fit together. a further challenge within this was recognition that many individuals come to the practice of iwcm from different disciplines and backgrounds and also may go on to a variety of roles in their professional life. a strategic approach needs to integrate data from specialists, for example engineers and analytical chemists, operating across a range of sectors that can appear remote from each other, and which require very different types of education and training, and yet each has an important role in different parts of iwcm. for example, whilst policy makers may never undertake a technical role, they will be called on to set objectives or develop policy that technical teams will have to implement and which need to be underpinned by high quality science and engineering. a strategic risk management approach to developing management capacity a framework for the evaluation of iwcm in kazakhstan was developed by watt, 2014b based on the international risk governance council (irgc) risk governance framework (irgc, 2005, renn, 2008, renn and walker, 2008; see fig. 2). the framework separates the process of risk governance into a number of different elements that make the process easier to understand. the first stage of the irgc framework, known as ‘pre-assessment’, highlights the importance of context for anchoring the subsequent risk management to the aims and objectives of the organisation mandated to manage the risk, and discuss ways that the local context can be established with a clear recognition of the benefits of the water being managed. pre-assessment is undertaken by both managers and technical specialists together, and can framed in many different ways – physical (e.g. hydrology, climate, ecology) and human (e.g. sustainability, economy, use to which resources are devoted). pre-assessment also evaluates 38 meyer et al. (2016) constraints placed on options for risk management by scientific conventions utilised, the law and regulatory arrangements. within i-web, this pre-assessment process involved interviewing a range of stakeholders including policy-makers, practitioners, industry representatives and academics to understand their current working practices, challenges and ambitions (see nireas, 2013). this initial needs assessment supported the identification of a broad set of skills required in teaching and practice, encompassing social, environmental, technological and economic aspects of sustainable water-land management. specific topics identified included water indicators and monitoring (including statistical methods and modelling), geoinformation and water treatment technologies and methods to the strengthen cooperative working between diverse actors (e.g. public authorities, universities and research institutes, ngos, governmental and international organisation), including the relevant laws, finances and management approaches pertaining to surface and ground waters both nationally and internationally (nireas, 2013). fig. 2 framework of the functions of the risk governance at strategic level (adapted from bunting, 2009) the second stage, risk appraisal, involved gathering and sharing data from scientific assessments of the water supply and its quality undertaken by several disciplines e.g. hydrologists, climate change scientists, agricultural scientists and economists. within i-web, this stage took the form of a specialist workshop on iwcm methodologies and practices where representatives from a range of kazakh and eu organisations presented research methodologies, current scenarios and future challenges from a range of organisational perspectives. the outputs of this workshop firmed the basis of the development of the ‘iwcm in kazakhstan’ handbook (meyer and lundy, 2014) which includes concepts of iwcm, methodologies and supporting tools for iwcm, management skills for building capability, capacity and impact, best practice examples for water treatment, basics on the sustainable use of water resources in kz, a concept of iwcm for kz and transboundary catchment issues and future integrated management. in the current model, this stage is an extension of the risk assessment referred to by the nas (1983) in the quotation above to include evaluation of public (or other stakeholder) concerns, which may impact on the way that management options can be evaluated. the third stage, characterisation and evaluation is the core of the process, best undertaken by all involved, where the evidence from the risk appraisal is evaluated in the light of the organisational values set out in the first stage. this is where a judgement is made on the acceptability of a risk and leads to one of three possible management actions – do nothing, ban some proposed or current activity or manage the risk. within the i-web programme this stage took the form of presenting the results of the pre-assessment process to members of the iweb international activity board (iab) for their comment and feedback on data collected and its interpretation. the i-web iab currently consists of over 20 members from a range of academic, policy, and professional/industry backgrounds who voluntarily participate in annual meetings to share knowledge on iwcm challenges within their sectors and comment on iweb outputs as they develop to collectively take forward best practice within iwcm in kazakhstan. this iab approach is a co-owned mechanism to facilitate the development of closer links between academia and practice for mutual benefit; enhancing the skill sits of graduates and hence graduate employability (through ensuring graduates have the skills employers need) as well as an awareness of the challenges they face. the fourth stage, risk management, shows how policy or management options can be developed based on the judgement made and implications from the technical evidence. a number of generic approaches were presented taking into account the extent to which stakeholder concerns needed to be incorporated. as an example, if scientific uncertainty was very high, a risk management decision might be required to be made by the government or a regulator to address public concern. in the absence of scientific data this might be made on the basis of a risk philosophy such as the precautionary principle with some form of stakeholder agreement (or societal endorsement) needed on the level of precaution required. within iweb, the management options developed were three-fold involving staff re-training, the development of bolognacompliant academic programmes and the re-working of programme material to additionally form short continued professional development (cpd) courses. more specifically, using outputs of the stage 1 and stage 2 activities, and following input and refinement of the stage 3 activities, findings derived were used to develop a bespoke intensive re-training programme for 30 kazakh academics. new knowledge developed was shared both horizontally, through seminars at each participating institution, and vertically through the subsequent development of learning materials for msc and phd teaching and research programmes as well as the more vocational cpd courses. the fifth element of the risk governance framework highlights the importance of communication (both internal and external), by positioning it in the centre of all of the other activities. a number of approaches have been developed depending on the nature of the risk, which is tasked with dealing with it and their relationship to other risk management as a basis for integrated water cycle management in kazakhstan 39 stakeholders. in i-web, communication was both a central challenge (language, cultural and experiential) and a core area of activities, which was addressed through multiple routes with particular focus on developing strong partnership working approaches. the wider context for this is that, together with many other sectors, communication and partnership working is now fundamental to water resource management legislation in many eu and central asian countries as its recognised that there are practical limits to the application of a topdown legislative approach as it is often difficult to enforce. it is increasingly appreciated that the existence of legislation alone is not enough to ensure environmental protection, because when water pollution occurs, it is often the result of ignorance and neglect rather than deliberate acts (chatfield and lundy, 2016). over the last twenty years a range of alternative cross-sector partnership approaches have been developed to protect the water environment, involving regulators, industry partners and communities, working together to promote good practice and improved standards. in recognising the success of such, often voluntary, partnership initiatives, legislative frameworks increasingly include a requirement for partnership working as a core element. these include, for example, the eu water framework directive (eu wfd, 2000), the eu floods directive (2007), the integrated pollution prevention and control directive (eu, 2008) and strategic environmental assessment directive (sea, 2001). whilst actual data on the benefits of a partnership working approach is hard to source (slater et al., 2007, reed, 2008), the literature identifies a range of reasons for collaborative working. the development of a forum where industry, regulators and communities can work together provides a constructive arena for those affected by decisions to influence those decisions which may affect their activities (e.g. industry) and or quality-of-life (local communities). it can facilitate the breakdown of legislative, institutional and social barriers to changes, supporting the development of novel options which are workable and acceptable within national and local regulatory and operating contexts (van herk et al., 2011). partnership approaches can raise awareness of environmental issues, making use of the knowledge and expertise held by a wider range of stakeholders and generating approaches which have higher levels of regulator, organisational, sectoral and wider public acceptance, commitment and support (cis, 2003). within an i-web context, the iab was the forum that brought individuals from a range of sectors together with a common goal of enhancing water resource management within not only kazakhstan but the central asian region as whole. the iab activities commenced with kazakh partners pro-actively identifying and contacting a range of environmental protection specialists, water managers, policy makers and users to join discussions on enhancing the management of kazakhstan’s water resources. with national government recognition of the challenges being faced, there was interest in the iweb iab from a range of sectors, although bringing all interested parties together was a time-consuming process. it is well recognised that partnership working is a long process, that successful partnerships grow incrementally and evolve through the building of trust and shared experiences (slater et al., 2007). the role of a ‘local champion’ – a person who is known by all parties, and is passionate and enthusiastic about the initiative in hand is critical in the early stages of partnership building to both bring on board other partners and strengthen commitment to the process (morris, 2006). within i-web each of the local kazakh university partners took the role of ‘local champion’, often using a combination of local knowledge and personal contacts to bring relevant stakeholders to the table together. methodologies and supporting tools for supporting implementation of iwcm in implementing iwcm in practice, it is widely recognised that water resource (wr) systems are among the most complex systems to cope with when analysed from a risk management perspective. risk management of wr systems has to include the identification, assessment, and prioritization of risks in order to implement coordinated actions to reduce, monitor and control the probability and/or the impact of any plausible events. a short list of the type of events that are usually of concern includes climate change, hydrological events, infrastructure safety, system management policies, effects of management policies in trans-boundary basins, accidental spills and incidents arising from other natural hazards. alone or combined, these events define scenarios to be addressed by the risk management strategy. ideally, any integrated wr strategic risk management platform should rely on a set of interconnected subsystems: 1. events: determination of plausible events and their probabilities. 2. impacts: assessment of every event impact. 3. monitoring: system monitoring to anticipate events and to support the quantification of associated impacts. 4. control: mathematical models of the wr system – frequently based on a gis platform – to predict and quantify the evolution of relevant parameters and variables of the system. 5. actions: wr system protocols and procedures to make decisions in real time, and for the short and mid-terms. the above subsystems are also connected through a loop because any taken action changes the probabilities and impacts of events. the whole platform has to be conceived and managed embedding the fundamental policy guidelines of the responsible organisation, and the participation of the stakeholders. in general, most basin authorities and administrations, mainly in developed and populated regions, run different institutional programs or units that address the above subsystems. these programmes have usually focused on the most plausible events, many of them of hydrological origin, with droughts and floods often being the main concerns. however, risk associated to infrastructure failures or to the accidental introduction of pollutants into the water bodies should be also 40 meyer et al. (2016) prioritized. a situation that requires special consideration is that of trans-boundary basins / wr systems. in this case, with different areas of the basin managed by different authorities, the existence of supra-national or supra-regional organisation to coordinate the basic policy objectives of the wr system is fundamental. this should be the “layer 0” underlying the participation of stakeholders and the existing risk management platforms in every sub-basin or subsystem. without this basic coordination, risk management has to be based on partial treaties and slow and limited mechanisms; this situation would call for the use of specific tools such as the methods developed in games theory to support the decisionmaking process in the absence of ability to control subparts of the system. madani (2010) reviews the applicability of game theory to water resources management and conflict resolution through a series of noncooperative water resource games. the study includes case studies all over the world, including central asia conflict on the legal status of caspian sea waters. the implementation of a strategic risk management platform requires the availability and integration of data, models and networks, including at least the following:  historical records of the wr system to support conceptual models of subsystems, the analysis of trends in selected variables, extreme hydrological events estimations, and the calibration of mathematical models both deterministic and statistical. these records should at least include data series of: runoff at selected control points along rivers, reservoirs storage and operation, piezometric levels in selected points in the main groundwater bodies, rainfall and other meteorological variables, basic quality parameters in surface water and groundwater at selected points, water consumption for irrigation, energy production and urban use, evapotranspiration, and series of any other relevant information regarding the characteristics of the wr system. the length of the series is relevant and if no information is available, or the series are very short, data series from similar locations might be useful.  a complete and sound hydrological and hydrogeological description of the system.  monitoring networks to increase the length of existing historical records, and real-time networks connected to feed alert systems. the latter might require rainfall and rainfall intensity, river and/or channel flows, reservoirs levels, critical quality parameters, etc.  conceptual and qualitative models to understand the main subsystems flows and interactions, including surface water and groundwater.  rainfall – runoff sub basin models.  mathematical flow models of the main groundwater bodies.  flood simulation models for the main basins / sub basins with higher flood risks.  basin / sub basin models that integrate both surface water and groundwater systems with capabilities to simulate both flows and water quality. geographical information systems are basic tools to organize the basin information and in many cases they support the use of models for different purposes. there can be other types of water resources like water imported from other basins, desalinated water or treated water. in this case, the proper parameters to characterize these resources have to be also included in the above listing. note that this is a basic list of required data, monitoring networks and modelling tools to build a strategic rm platform. in practice, it is necessary to develop decision support systems (dsss) that help the decision-maker to analyse and understand the dynamics of the system, foresee short and mid-term evolution, and to assess the impact of alternative decisions. dsss are tools specifically designed for a given system and specific purposes (although the software platform can be design to be adapted to different basins). they usually integrate several mathematical models of the system, and stochastic simulators for hydrological inflows, that can cope with wr system operation under drought or flooding conditions, simulating short, mid and long term scenarios to remediate water scarcity or pollution problems, etc. the use and development of dsss has historically run in parallel with the development of graphical capabilities in computers. an early dss, under continuous development and well described in scientific and technical literature, is aquatool, see andreu et al. (1996). this tool has been evolving since the first releases and includes simulation and optimization of wr management accounting for the uncertainty of hydrological inflows in the system and many other features. it has been applied in many basins around the world (spain, argentina, brazil, italy, mexico, bosnia, chile, morocco, algeria, ecuador, peru, etc.), and is supported by a friendly graphic user interface (gui), spatially referenced, that allows its use by personnel with a low levels of training in the use of computers. the use of risk as a criterion to manage a water resource (wr) system – risk based wr management was described and applied by capilla et al. (1998). other authors, e.g. rousta and araghinejad (2015), illustrate how to incorporate multi-criteria decision making into a dss using objective functions that include multiple goals. these goals or objectives can be as diverse as the fulfilment of ecological flows, the satisfaction of minimum levels of water demands, the maintenance of levels in lakes and reservoirs, the amount of energy generated in hydropower plants or maintenance of thresholds in the exploitation of groundwater bodies, etc. note that the mathematical formulation of the multiple objectives optimization requires the definition of weights to be applied to reflect the importance to be apportioned to a prior decision reflecting the fundamental management policy. integrated water cycle management also requires working with scenarios that account for future climate change. in this case it is necessary to work with scenarios that are downscaled from general circulation model (gcm) results. the reports issued by the intergovernmental panel on climate change (ipcc), see ipcc (2014) are the primary source of information. risk management as a basis for integrated water cycle management in kazakhstan 41 however, for specific geographical regions and basins, it is necessary to analyse which gcm best reproduces the local conditions, and to downscale the low resolution data provided to a scale that allows more accurate determination of impacts on water resources. chirivella et al. (2015) show the results and methodology of a study in which dynamic and statistical downscaling methodologies are compared. conclusion on the benefits of implementing a wfd risk management approach in kazakhstan whilst both the eu and kazakhstan are moving towards implementing an iwcm approach, the launch and phased implementation of the eu wfd has greatly accelerated progress towards its full implementation throughout europe. as a single piece of legislation that all european member states must implement, it requires the collection of data, involvement of all stakeholders and the development and implementation of science-based programmes of measures via the use of common methodologies and processes. all data collected is freely available with the use of common methodologies promoting the harmonization of management approaches both within and, crucially, between member states. as such, this transparent approach facilitates transboundary dialogue with the development of common goals, languages and tools identified here as a strong mechanism for intra-regional co-operation irrespective of national boundaries. therefore risk management is applied from strategic to local application scales. whilst the adoption of legislation such as the kazakh water code indicates the recognition of, and priority placed on iwcm within kazakhstan, no single country which shares transboundary waters can fully implement an iwcm approach in isolation. whilst arguably not a short-term objective, the need for a central asian water framework directive approach which would co-ordinate and harmonize the emerging activities taking place across the region is identified as a priority requirement. in developing such an over-arching framework, the current transboundary river basin agreements (table 2) can be considered as an initial agenda for discussions to further develop and strengthen partnerships between business, regulatory and academic sectors at a national and international level to face the common need to implement robust approaches to water resource management in the face of a changing climate. furthermore key aspects on the adaptation to climate change have to be considered including establishment of core principles and approaches, international commitments, policy, legislation and institutional frameworks, information and monitoring needs for adaptation strategies design and implementation, scenarios and models for impact assessment and water resource management, adaptation strategies and measures for financial matters and evolution purposes (un ece, 2009). in developing and implementing approaches to ensuring water resources are available to meet the needs of current and future generations, europe and central asian are facing many common challenges. the opportunity for closer collaboration between regions is highlighted here, with regard to both the need to develop a regional approach to iwcm and the role that individual countries can play in contributing to its delivery. with a specific focus on supporting the development of iwcm within central asia, key challenges identified by lundy and meyer (2014) included:  persuading neighbouring upstream countries that it is in their interest to work on a catchment basis  developing increased collaboration as opposed to competition over use of water resources within catchments e.g. to address tensions between agriculture and energy production  compliance with state legislative controls and facilitating stakeholder participation  scoping and developing a central asian water framework directive; what can be learned from international best practice and mistakes? 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(2009) pp. 37-47 floods and weather in 1342 and 1343 in the carpathian basin kiss, andrea1 1university of szeged, department of physical geography and geoinformatics. 6722 egyetem u. 2, szeged, hungary abstract concerning weather, weather-related extremes and catastrophic consequences, 1342 was an extraordinary year in most parts of central europe, even in such an extraordinary decade as the 1340s. accounting with the seven flood events (including one danube flood) mainly of great magnitude, at present 1342 is the most important known flood year of medieval hungary. moreover, in this year extraordinary weather conditions, such as a mid-autumn snowcover were also reported. however, in the eastern parts of the carpathian basin not only 1342 but also 1343 was a significant flood year with six reports on flood events occurred in the upper and upper middle sections of the tisza catchment. in the present study, an overview of these events is provided, based on the information preserved in the most typical contemporary, well-dated source type of medieval hungary, namely charters. the aim of the study is, on the one hand, to draw attention to the flood and weatherrelated evidence found in charters, and to provide a methodological background for further evaluation and utilisation of this source type in historical weather and flood research, through the very typical example of the years of 1342 and 1343. on the other hand, another aim is to discuss and analyse the unique nature of these two years in medieval hungary, and (beyond the well-known year of 1342) to draw attention to the, up to now somewhat neglected, year of 1343. deep snow, ice flood, extreme rainfall and a devastating millennial summer flood event: 1342 (and 1343) in (west) central europe 1342 became famous for its hard winter with abundant snow and very rainy summer as well as autumn in central europe and beyond. these weather conditions caused in large parts of (central) europe three main flood waves: one in february, a second one in april and a third one in july. out of these three flood waves the summer flood happenned to be an extreme, millennial flood event with disasterous consequences which, together with the next year’s unfavourable wet weather conditions (mild winter, cool and wet spring, wet summer), caused great hunger and famine in most of the german areas by 1343 and 1344 (glaser r. 2008). although two of the flood waves, namely the february and april floods caused great damages in the czech areas, there is no report available about any damages concerning the summer of 1342 (brázdil r. – kotyza o. 1995). moreover, in the area of the eastern alps none of the three floods had so disasterous effects as in other parts of west central europe (rohr ch. 2007). about the 1342 weather and floods a concise overview of the international literature was presented by brázdil and kotyza (1995). another, detailed overview of the 1342 events, from various viewpoints including causes, damages and other consequences, was provided by rohr (2007), as well as by glaser (2008). large-scale geomorphological and landscape-change consequences of the disasterous summer flood event were studied by bork and his colleagues (e.g. 1998). in contrast with the great attention turning towards the events of the year 1342, there is not much available about 1343 in the scientific literature. almost all information about the somewhat special, unusually wet character of this year and its possibly also hard consequences were only detected in germany. in this case, together with the catastrophic events of the previous year, the unfavourable weather conditions were also blamed for the famine concerning the southern german areas (glaser r. 2008). some other evidence, however, might suggest that the danube in bavaria caused problems also in other times during these two years, since flood damages were reported at the monastery of oberaltaich concerning autumn 1342 and spring 1343 (rohr ch. 2007). what happenned in the carpathian basin in the same time? the special character of the 1340s and 1342 in the carpathian basin was partly emphasised by kiss (1996, 1999). nevertheless, on the basis of an enlarged database of legal documentary evidence (charters), a new, more complete overview and analysis can be presented. charters: an unique well-dated medieval legal evidence concerning these two extraordinary years, information about the events occurring in the hungarian kingdom, which covered almost the entire carpathian basin – including the present-day areas of hungary, slovakia, and parts of ukraine, romania, serbia, croatia, slovenia and austria – is mainly available in legal documentation, namely charters (see kiss a. 1996, 1999). characteristic advantages and disadvantages of this type of weather and flood documentation lie in their legal character: the main aim of preparing these documents was to document and preserve the most important points, objectives of the legal process as a proof of ownership patterns for the future (often for centuries). consequently, flood or weather circumstances are mentioned only if they 38 a. kiss joeg ii/3-4 obstructed the completion of the legal procedure during field survey. in other (less frequent) cases, flood/weather circumstances obstructed travel and thus legal procedure/trial had to be postponed and this fact (together with circumstances) had to be reported to the higher authorities or permission to be asked for postponing/prolongation of procedure. occasionally, weather-related information (e.g. proof of a late harvest) can be detected in other cases, such as witnessed illegal harvesting or using force during (well-dated) harvesting time etc. clear advantages of charter evidence are, compared to most types of medieval documentary evidence, their exact and highly reliable dating (legal-administrative documentation), the punctuality of location and the several elements, main environmental conditions of the area, often described in the main text body. disadvantages are that the date(s) of observation is not necessarily the date of the beginning and the end date of the flood event, but only a day or days of the ongoing flood and weather events. moreover, the beginning and end dates of flood events/weather phenomena and their main (e.g. material, human) consequences are mainly unknown. in this sense, a major difference from (western or other) narrative evidence is that in charters mainly flood appears as a natural hazard while in narratives flood is mainly reported because of its catastrophic consequences. similarly, the area a charter usually refers to is often restricted to a small location and thus, in the majority of cases little is known about mediumor largescale patterns. except for one case (town burning down in 1342), all weatherand flood-related information concerning the years of 1342 and 1343 has survived in charters. the spatial distribution of reported weather and flood events of 1342 and 1343 is presented in fig. 1. the present analysis provides us with fragmentary picture on what happenned in 1342-1343 in the carpathian basin, not only related to weather, but also flood events: data available only for those dates and in those cases, areas when and where legal procedure took place and later weatherand/or flood-related information was included in the charter. thus, we can presume that large-scale patterns would have shown a certainly more complex, and possibly even more ’serious’ picture, especially concerning flood events. a fragmentary picture? weather reports from 1342 and 1343 only sporadic information is directly available concerning the weather of 1342: these data preserved in charter evidence. amongst this evidence, a reference can fig. 1 floods and weather events (or related information) documented in 1342-1343 in the hungarian kingdom (described here together with the croatian kingdoms). deserted settlements are determined with brackets joeg ii/3-4 floods and weather in 1342 and 1343 in the carpathian basin 39 be found in a charter concerning rainy weather (’et quia eadem die pluuiosum tempus asseruisset’), reported on 26 may in 1342 (nagy i. 1884), due to which reason the field survey of chalanus, located in historical bihar county (today cenaloş in romania), could not be carried out on that day (see fig. 1). on 11 august in 1342 during the perambulation of rendec (today ajkarendek) landed posession at the boundries of ayca (ajka) and louuld (today kislıd/városlıd), located in the central transdanubia along the torna river (dl 66126; piti f. 2007a; see fig. 1), the owners of some arable lands prohibited others to take the harvests from their arable lands and also to take the already harvested shooks of grain (’de quindecim iugeriis fruguum quindecim capecias similiter prohibuissent quas in eadem terra seminatas inuenissent’). although no medieval harvest date series are yet available for this region or for hungary, a significant amount of data can be found for the early modern period in the somewhat cooler and wetter szombathely (ca. 205 m a.s.l.), located approximately 80 km west to rendek (ca. 250-280 m a.s.l.). in the 17th and 18th centuries, the share of harvesters, fixed towards the end of the harvest (of mainly wheat and rye), usually occurred around midand late july, sometimes earlier (szombathely town council protocols, vas county archives v/102a). late harvest(-ending)s could occur in early august (e.g. 5 august in 1675 and 1696, 6 august in 1700, 7 august in 1697, 9 august in 1705), too. in our present mid-14th century case, by 11 august one part of the crops have been already harvested, but still kept on the field, while another part was still waiting for harvesting. even if harvesting lasted probably longer in the 14th century than in the 17th century (see belényesy m. 1956), this means a rather late harvest time (especially if taking the 10-day difference between julian and gregorian calendars also into account), which presumably refers to cool late spring, early and midsummer conditions. on 15 september in 1342 (nagy i. 1884, piti f. 2007a) a perambulation of the doubted boundary-line between possessio bahun (today báhoň in slovakia) and possessio zamul (later deserted land) took place (medieval pozsony county; see házi j. 2000). nevertheless, because of the hard times (or the difficult weather conditions) and the magnitude of snow (!), it was not possible to perambulate the boundaries, and measure the area of lands (’propter temporis gravitudinem et nivei magnitudinem reambulantes determinative mensurare non potuissent’). original dating of the perambulation is clearly defined ('in predictis octavis festi nativitatis beate virginis'), and based on the earlier course of the legal debate (previous meeting: 1 august; later meeting: 8 november) no very different (much earlier or later) dating is possible. as such, we can presume that in the areas of present western slovakia the perambulators witnessed in a lowland area (ca. 150-180 m a.s.l.) extraordinary weather conditions with a significant amount of snow at a very early date, namely in mid-september. according to the (contemporary) georgenberger chronik, referring to the town of lewtscha (today levoča in northeast-slovakia) one of greatest reported (medieval) fires occurred in 1342 (szentpétery i. 1938: ’anno dni mcccxlii …. czu der selbin czeit ist dy stat lewtscha verprant, vnd also sein auch dy altin prife des lanids des meiste teil verprant.’). although applying different words, the same information was included in caspar hain’s 17th-century regional chronicle (bal j. et al. 1910-1913), based on (local) archival evidence. since no more data is available (e.g. in which part of the year the fire occurred), even if it is clear that weather conditions had to be at least partly responsible for this disasterous event (e.g. strong wind, drought and/or hot/very frosty, cold weather), no firm conclusions can be drawn on prevailing weather conditions. the scarcity of known weather events, remained to us reported in the carpathian basin, does not allow us to draw further conclusions. nevertheless, the report on a potentially quite late harvest in the mid-transdanubia, and the extraordinary mid-september deep snow in the lowland areas of present western slovakia suggest generally preavailing cool conditions for late springsummer and around early-mid autumn in 1342. no weather-related reports are yet known concerning 1343. what makes these two years really special is the unusually great amount of flood reports, reflecting on the possibly extraordinary (wet) weather conditions and especially intensive large-scale cyclonic activity. 1342: the most important flood year in medieval hungary? due to its flood events of great magnitude (e.g. summer), the year of 1342 is accounted for in most of the contemporary european narratives. up to date, no european narrative is known to mention that these or any other flood events in 1342 would have as well appeared in hungary. the seven reported flood events of this year, presented here concerning hungary, can be detected merely in domestic legal documentation: only charters preserved their memory (for locations, see fig. 2). the great winter flood in a broader context the first known flood event of 1342 occurred in early february. at the (former) lower course of the hejı 40 a. kiss joeg ii/3-4 and szinva waterflows, close to the sajó river, the perambulation of the former deta and korh landed possessions (both were deserted later: györffy gy. 1987) in borsod county was obstructed by a great flood event (’nimia aquarum inundacio’). a speciality of the description is that on 9 and 10 february perambulators could not even approach the areas, although they did make attempts. on the next day, on 11 february there was already no problem with reaching and surveying the area, but still they could not measure the debated landed portion, they could only estimate the size of the land (dl 75835, 3448, 40902; see also piti f. 2007a). for the february events good parallel can be the description of franciscus pragensis, who dedicated a long description for the great flood event: from his notes we can learn that on 1 february warm air masses arrived which were followed by rains. this mild weather, after the preceding hard winter conditions, melted the snow, broke up the ice, and caused great ice flood (loserth j. 1875; for the analysis of vltava, elbe and upper-morava flood events, see brázdil r. – kotyza o. 1995). according to the swiss johann von winterthur, flood flashed through the upper, alpine sections of the danube on 2 february, and in the same time sea surge caused damages in venice (baethgen f. 1924). spring floods on 6 march, the division of the landed possessions of berkesz, bodony and harabur, located in historical szabolcs county along the tisza river (csánki d. 1890; németh p. 1997), was obstructed by the great flood of waters, which occurred in those areas (’nimia aquarum inundacio’) (dl 31242; see also piti f. 2007a). since bodony was located at the upper-tisza, the great flood of waters could most probably refer to the tisza and partly to its upper tributaries. fig. 2 flood reports in the year of 1342 in the hungarian kingdom. note that the medieval borderline, running along the ridge of the carpathians, also defines a geographical and hydrological boundary line (of major catchment areas – e.g. tisza). deserted settlements are signed with brackets joeg ii/3-4 floods and weather in 1342 and 1343 in the carpathian basin 41 on 11 april great extent of waters was observed, at this time during the perambulation of aranyan landed possession (today deserted land in serbia close to apatin; see györffy gy. 1987), in historical bodrog county (nagy i. 1884). in the text not the usual ’inundacio(nes) aquarum/aque’ appeared, but a broader information, namely the great amount and magnitude of waters, in the extensive floodplain of the danube (’abundancia et multitudo aquarum’) where the lands of aranyan were located. the mentioned great waters make it probable that it was not the mere result of one flood (mainly of the danube), but we might have to count with more than one flood waves, culminating in this lowlying, extensive floodplain, and probably also with the influence of the drava river whose inflow is located south to the study area. additionally, the appearance of inland excess waters, which in wet years often occur parallel or after flood events, is also quite probable. moreover, as a factor obstructing the legal process, this great extent of waters probably also means a longer-term inundation in the area. the charter itself is important since the hydrological conditions of the area cannot be separated from that of the danube (and also partly the drava) and thus, the high water level, or flood level of the danube. dated to the beginning of april flood, caused by the melting of great amount of snow, is mentioned by the cistercian monk, johann von viktring, which affected the waterflows of europe, and according to the description, the result was catastrophic (schneider f. 1910; for more analysis, see: rohr ch. 2007). however, due to the little difference in time, the danube flood in south-hungary cannot be the continuation of the westcentral european flood event. as there is no significant waterflow coming to the danube between its upper and lower carpathian-basin sections, there should have been at least one flood event of the danube in march at the upper sections of the carpathian basin. there is a good possiblity that a flood wave at that time was already coming from the west; this case shows parallels to another (waves of) flood event, occurred in june of 1402 (see 27 june in hungary: dl 78505; 29 june in austria: pertz g. h. 1851). still in the same month, at the end of april in 1342, another flood event (’inundacio aque’) obstructed perambulation and land measurements along the zsitva river (žitava in slovakia). on 25 april the perambulation of a land portion between the landed possessions of ohaj and besenyı (today bešeňov and dolný ohaj in slovakia) had to be stopped close to the river due to the flood (nagy i. 1884). during a perambulation, taking place on 3 may at the northeastern sections of the middle-tisza, the swamps and the uninhabited lands caused by the great amount of waters (’propter paludes et terras inhabitabiles propter multitudinem aquarum’) is mentioned as an obstructing environmental circumstance which did not allow perambulators to proceed with the survey (dl 105741; see also piti f. 2007a). the landed possession of ladan, mentioned in the charter, is the present-day mezıladány (németh p. 1997), located at the main course of the tisza river in historical szabolcs county. since mezıladány is located in the immediate neighbourhood of the river, partly surrounded by wetlands (oxbows: former tisza-beds), the documentation of such wetlands in itself does not necessarily mean current hydrological problems, i.e. unusually much water in the area. the fact that some of the lands, exactly because of the great extent of waters, could not be reached (or even occupied by water) and some of the lands could not be measured suggests actual problems. namely that the extent of waters was presumably (much) larger than usual in the area. what is more, lands were mentioned to be uninhabited because of the great extent of waters, which – similar to the danube case in april – might easily also mean the (longlasting) presence of inland excess waters in the area. summer signal: missing or not? as we could see already at the beginning of the paper, perhaps the greatest flood event of the middle ages, with immense magnitude and damages, occurred in some parts of europe. this, however, does not seem to appear in medieval hungarian documentary evidence. one likely reason, as always, can be that it was simply not documented in the charter materials due to the fact that no legal procedure took place at that time in the problematic areas or documentation disappeared with time. nevertheless, the lack of documentation can also mean that there was in fact no such significant summer flood event in the carpathian basin at all. in west central europe one of the greatest known flood series occured around 21-24 july (brázdil r. – kotyza o. 1995; rohr ch. 2007; glaser r. 2008). this, however, was less characteristic in the eastern alpine region or in the czech lands (brázdil r. – kotyza o. 1995; rohr ch. 2007). as appears in the next case, even if the mid-summer signal is missing, a wet late summer-early autumn period may be responsible for a flood event reported in the southwestern part of the carpathian basin. autumn flood(s)? the early autumn (15 september) flood observation, close to the drava river at the landed possessions of vajszló, hirics and luzsok, can be taken as an indicator 42 a. kiss joeg ii/3-4 of a late summer or early autumn flood. the debated landed portion among the above-mentioned villages was inundated, and due to the swampiness and flood of waters (’propter paludinositatem et inundacionem aquarum’) – although the perambulation could be carried out –, exact land measurements had to be replaced by simple estimation (nagy i. 1887). the summer origin of this flood event is even more probable, counting with central and western european parallels, especially if we presume that this inundation of waters was in direct connection with the drave river and thus its alpine catchment. however, the flood also could be (at least partly or entirely) the result of inland excess waters. the rest of the autumn did not pass away without a flood event either. on 11 november along the tisza river (again at the northeastern part of the middle section), in medieval zemplén county, a land measurement could not take place because of the ongoing floods (’propter aquarum inundaciones mensurare nequivissent’) or an inundation as a result of series of flood events (nagy i. 1887). areas of the medieval maraza landed possession (maráza: later deserted, see csánki d. 1890) are today located in the neighbourhood of vel'ké trakany and čierna (in slovakia) along the tisza but also close to the latorica river. since in the catchment area of the latorica river secondary (autumn) precipitation and flood maximum is especially important (hajósy f. 1954), there is quite a good chance that the waters in flood were both the tisza and the latorica, and maybe also other waterflows in the area. midor late-autumn flood events are usually connected to the arrival of warm air masses rich in precipitation, driven by southern, southwestern winds from the mediterrannean. it is interesting to mention that great flood damages in padova and other parts of lombardia were documented by the contemporary chronicler johann von winterthur, which floods were caused by great november rains, accompanied by lightenings and thunders (baethgen f. 1924). another important flood year: 1343 while in most of the western literature 1342 is emphasised as a major year of floods, 1343 gained up to now very little attention, even if contemporary authors of western narratives, for example johann von winterthur, did spend quite much space to describe floods of this year. the year of 1343, apart from its special geographical extension (described below), shows rather interesting characteristics in the carpathian basin. fig. 3 floods in the year of 1343. green arrow shows the presumable connection between the two, early may cases: the upper-tisza flood waves reported on the middle-tisza (as one flood) with ca. one week delay joeg ii/3-4 floods and weather in 1342 and 1343 in the carpathian basin 43 in medieval hungary, the testimony of as many as six flood reports remained to us: all occurred in the northeastern parts of the carpathian basin, in the upper and upper-middle parts of the tisza catchment (for locations, see fig. 3). as we will see, in the flood history of the tisza catchment, the year of 1343 has rather great importance. winter flood of the tisza river the first winter case was observed on 11 february (and the days after) at the tisza river. the perambulation, taking place around the medieval landed possession of endes (as the northern neighbour of the abovementioned mezıladány) located in historical szabolcs county along the tisza river (csánki d. 1890; today part of mezıladány: németh p. 1997), had to be stopped at a fishing place caused by the fact that perambulators could not cross due to a flood of waters (’aquarum inundacio’). therefore, areas of the last sections of the planned perambulation were only estimated by ’eyeobservation’ (df 209593; see also piti f. 2007b). spring floods the next spring flood case was observed at the end of march and beginning of april, when, in order to introduce into the possession of a land in the former gelenes (gelénes; for location: csánki d. 1890) in historical szatmár county, not all the interested parties could reach the area because of an ongoing great flood event (’nimia aquarum inundacio’). those, who were able to attend the legal process were waiting for the others between 30 march and 2 april, yet without any success (dl 85252; piti f. 2007b). another spring flood was observed on 1 may and the following four days, during the perambulation process of zalouka and esen (csánki d. 1890, németh p. 1997; today solovka and esen in ukraine) located in historical szabolcs county close to the tisza river. the debated land portion at the zomua/zomaua waterflow could not be surveyed due to floods of waters (’inundaciones aquarum’), and thus, the size of the land was only estimated (df 233635, 233634; see also piti f. 2007b). the affected lands are located in the immediate vicinity of the tisza, so the waterflows and the area were clearly under the direct influence of the river. perhaps the same flood event on the tisza river reached the landed possession of kumleu (kömlı) in historical hevesújvár county in some days time and thus, maybe the effects of the same flood or those of a previous flood wave was reported. on 8 may, caused by the flood of water and great difficulties (’propter inundacionem aque et densitatem gravaminum reambulare nequivisset’), it was not possible even to start the perambulation or settle any of the landmarks, and thus, measurements of debated lands could not take place either (nagy i. 1884). as a parallel it has to be mentioned that, for example, johann von winterthur did mention concerning 1343 that there were great rains around easter time. these great rains caused flood, and problems did as well continue in summer when, for example, the rhein also flooded. moreover, series of flood events, caused by rainfall, continued in september. much rain and bad harvests, accompanied by floods and other problems, caused several problems: especially in the german areas high prices and hunger developed (baethgen f. 1924). summer and autumn floods the only known, clearly summer flood event occurred at the sajó river, only some kilometers from the place where the river enters the tisza. the unsuccessful perambulation process of szentalbert and kerencs landed possessions in borsod county was due to a flood event (’inundacio aque’), observed on 13 july (dedek l. c. 1924). since the area where the flood was reported is located at the sajó river, but very close to the inflow of the hernád river, and also close to the tisza, there is a good possibility that the hernád, but probably also the tisza were in flood or had high water levels in those days. although it is not a direct flood evidence, it is still worth mentioning that, related to a land purchase, on 6 september a number of old charters were transcribed by the convent of kolozsmonostor (cluj-mănăştur; today part of cluj napoca in romania) caused by the fact that the owner (pethew from neema; today nima in romania) of the landed possession (beeke or beche) did not dare to carry the originals with him. among the reasons the dangers of roads and obstructive waters (’propter viarum discrimina, aquarum impedimenta et hospitiorum incendia’) were mentioned (dl 27829; see also piti 2007b). the above-mentioned settlements are all located in central transylvania, in the vicinity or along the kis-szamos river (today someşul mic in romania). on 6 october at the landed possessions of homok and ketergény (today holmok and rozivka in ukraine) in historical ung county a debated land portion could not be measured, only estimated, due to a flood event (dl 69670; see also piti f. 2007b). the mentioned lands are located in the catchment area of the ung (today už) river, in which area october as a secondary flood maximum is rather pronounced in the 20th century, and clearly shows the arrival of mediterranean humid air masses (see e.g. hajósy f. 1954). the spatial and seasonal distributions of the 1343 flood events suggest that we talk about an especially 44 a. kiss joeg ii/3-4 important flood year when ongoing flood events were observed in each season, at the upper and upper-middle parts of the tisza catchment. whereas floods of 1342 affected both main catchment areas, namely those of the danube and the tisza rivers, all six reports referring to 1343 reflect on the flood events of the (upper and upper middle sections) of the tisza catchment. thus, concerning the eastern parts of the carpathian basin 1343 has at least the same or even more importance than 1342. how special were these two years amidst the known flood records of medieval hungary? in late medieval hungary the decade of the 1340s was rather special: far the greatest amount of flood events is known from this decade. out of the twenty one presently-known flood events, thirteen occurred in these two years of 1342 and 1343 (fig. 4). in general, most of the flood events, for which we have reports, occurred in the tisza catchment or on the tisza river itself: out of the five danube-catchment flood events of the 1340s, three were witnessed in 1342; out of the two danube floods of the decade one with a great extent of waters took place in 1342, and another (great) one in 1344 (fig. 4a). typically, almost all great flood events occurred in the more continental eastern river catchment of the tisza. seasonality patterns are also interesting and typical: in this case the overwhelming importance of (great) spring flood events have to be emphasised. winter floods were reported in every second, third year; every year between 1342-1344. interesting is the fact that only one summer flood is known from the whole decade (fig. 4b). as we could see, accounting with numbers of the two years subject to discussion, floods were reported seven times in 1342, while six floods in different places were witnessed in 1343. as such, 1342 and 1343 are the most prominent flood years known in the later middle ages. other ’famous’ flood years, according to our present knowledge, were with four-four mentionings in 1399 and presumably in 1440, three-three in 1338 and probably also in 1346, 1454 and 1499, respectively (see fig. 5). in 1342, one winter flood (tisza catchment), four individual spring floods (two-two in both catchments), and two autumn floods (one-one in both catchments) were reported, and there is a complete lack of summer floods documented (figs. 2 and 6). therefore, except for winter when flood event was reported only in the tisza catchment and summer when flood signal is lacking as such, spring and autumn flood events affected both main catchment areas of the carpathian basin. both the winter and two spring floods were great in magnitude, while both the danube in early april and the (upper-)tisza in early may were surrounded by a large extent of inundated areas, in which case not only flood but also the appearance and negative effects of inland excess waters were rendered. concerning numbers, 1343 is a flood year of upmost importance in the tisza catchment and the eastern part of the carpathian basin. floods occurred in all seasons, but reported exclusively in the tisza catchment: one-one in winter, summer and autumn; while three separate reports are available for spring tisza floods. out of the three spring floods two refer probably to the same flood wave(s) on different sections of the river, with approximately one week difference. in 1343 (only) one event was reported as a great (tisza) flood (see figs. 3 and 6). similarly 1342 and also to the whole 1340s, tisza floods in 1343 were exclusively reported on the lower parts of the upper-tisza and the uppermost sections of the middle-tisza, and thus, no evidence is available referring to most of the middle and lower sections of the river and its catchment area. fig. 4 floods reported in the 1340s according to major catchment areas (a), and seasonality of flood events (b) (for detailed information, see kiss 2010; submitted) joeg ii/3-4 floods and weather in 1342 and 1343 in the carpathian basin 45 typical common characteristics of the two years are the unusually great number of flood events, both separated and spreaded in space and time, and also the great importance of spring floods, in both years rather evenly distributed in time. another similarity is that the flood events in most cases occurred on or in the closest vicinity of the two (or three: also accounting with the drava river) major rivers of the carpathian basin, and only in two-two cases mediumor small-size rivers/river catchments were affected (fig. 6). comparing the two greatest flood years, apart from the clear difference concerning the catchment areas affected (1342: danube and tisza; 1343: only tisza), an important other difference is that most of the floods reported in 1342 were marked as great or extensive in magnitude: it is true for all winter and spring floods detected in this year, either occurred on the tisza or the danube catchments. whereas in 1342, both in case of the danube (early april) and in case of the (upper)tisza in early may, the extent water surfaces might suggest the existence of inland excess waters, only the word ’inundatio’ was used in 1343 in the flood cases mentioned related to the tisza catchment. nevertheless, in the number of flood events reported, in the eastern parts of the carpathian basin, namely in the catchment fig. 5 annual distribution of known flood reports in late medieval hungary (a developing database – kiss 2010 in prep.). note the outstanding amount of flood events reported in 1342 (7) and 1343 (6) fig. 6 seasonal distribution of 1342-1343 flood events according to rivers and catchments (dc=danube catchment, tc=tisza catchment). for locations and areas affected, see figs. 1-3 above 46 a. kiss joeg ii/3-4 area of the tisza river, 1343 has at least the same or even more importance than the year of 1342. conclusions and outlook prevailing wet character of weather can be detected in central europe in 1342, which on the one hand led to three devastating flood waves in 1342, and presumably also at least two in 1343. in the latter year not only in central europe, but reports are also available referring to northern italy. moreover, extraordinary cool and wet weather and floods resulted in need and hunger in the german territories and austria in 1343 and 1344. with reference to the carpathian basin, no directly weather-related information is yet available concerning 1343. in 1342, most probably generally preavailing cool and maybe also wet late spring–summer conditions caused the presumably late grain harvest in westhungary. the mid-september snow report in present-day west-slovakia provides us information for presumably extraordinary cold weather in early autumn of 1342, when in the same time flood was observed in the southwest, in the immediate vicinity of the drava river. the great amount and magnitude of flood events might suggest a precipitation surplus in winter, spring and latesummer and autumn in 1342. based on the large number of flood events, covering each season, wet character of 1343 can also be rendered. 1342 and 1343 are clearly the most important flood years reported in medieval hungary. the seven flood events in 1342 are relatively evenly distributed between the two main catchment areas, all six flood reports refer only to the events occurred in northern, northeastern parts of the tisza catchments. most of the flood events in 1342 were either great in magnitude or could be connected to great extent of waters. another speciality is that, similar to the czech lands and austria, the famous millennial 1342 summer flood event, causing great damages in west central europe, cannot be really detected in the carpathian basin. in contrast, in 1343 floods were observed along the tisza river and in the tisza catchment in all four seasons. in 1342, both along the danube and the tisza rivers, at least concerning spring time, we presumably should count with great extension of inland excess waters, which waters perhaps still caused problems in 1343. among future tasks related to this subject, it could be important to find more parallels with the neighbouring areas and other parts of europe. concerning large-scale patterns, a complex analysis of these unique flood years on an european level (e.g. mediterranean cyclonic activities included) might also be an interesting direction of research. moreover, another relevant task could be to detect possible short and medium-term economic and social effects of this anomaly in the hungarian kingdom. acknowledgements the author wishes to express her thanks to ferenc piti and györgy szabados (hungarian academy of sciences, hungarian medieval studies research group, szeged, hungary), kathleen pribyl (school of environment and technology, university of brighton, uk), and to christian rohr (dept. of history, university of salzburg, austria) for their useful suggestions. the present research is supported by the eu project (fp-6) called ’millennium’. references belényesy m. 1956. a földmővelés magyarországon a xiv. században. századok 90/4-6: 517-555 bork h.-r. – bork h. – dalchow c. – faust b. – piorr h.-p. – schatz t. 1998. landschaftsentwicklung in mitteleuropa: wirkungen des menschen auf landschaften. gotha: klettperthes, 328 p brázdil r. – kotyza o. 1995. history of weather and climate in the czech lands i (period 1000-1500). zürcher geographische schriften 62, zürich, 1995. pp. 114-115, 168 csánki d. 1890. magyarország történelmi földrajza a hunyadiak korában. budapest: magyar tudományos akadémia, pp. 475, 511, 513-514, 525 glaser r. 2008. klimageschichte mitteleuropas. 1200 jahre wetter, klima, katastrophen. darmstadt: primus verlag, pp. 66, 76, 84-85, 88-89, 225, 230-231 györffy gy. 1987. az árpád-kori magyarország történeti földrajza. vol. 1. budapest: akadémiai kiadó, pp. 706-707, 770, 783 hajósy f. 1954. adatok a tisza vízgyőjtıjének csapadékviszonyaihoz. budapest: akadémiai kiadó, p. 24 házi j. 2000. pozsony vármegye középkori földrajza. pozsony [bratislava]: kalligram, pp. 169-170 kiss a. 1996. some weather events from the fourteenth century (1338-1358). acta climatologica universitatis szegediensis 30: 61-69 kiss a. 1999. some weather events in the fourteenth century ii. (angevin period: 1301-1387). acta climatologica universitatis szegediensis 32-33: 51-64 kiss a. (2010). az 1340-es évek árvizei, vízállás-problémái és környezetük, különös tekintettel az 1342. és 1343. évekre. submitted to: almási t. – szabados gy. – révész é. (eds.). fons, skepsis, lex. szeged: szte történeti segédtudományok tanszék-szegedi középkorász mőhely, pp. 181-193 kiss a. (2010). floods and long-term water-level changes in late medieval hungary. phd dissertation at the central european university, budapest. in prep. rohr ch. 2007. extreme naturereignisse im ostalpenraum. naturerfahrung im spätmittelalter und am beginn der neuzeit. köln-weimar-wien: böhlau verlag, pp. 202, 226228, 448 primary sources and charter/regesta editions baethgen f. 1924. monumenta germaniae historica. scriptores rerum germanicarum. nova series. chronica joeg ii/3-4 floods and weather in 1342 and 1343 in the carpathian basin 47 iohannis vitodurani. berlin: apud weidmannos, tomus 3, pp. 189, 195, 200-201, 203-207, 213, 215-216, 238 bal j. – förster j. – kauffman a. 1910-1913. hain gáspár lıcsei krónikája. lıcse [levoča]: reiss józs. t. könyvnyomó intézete, vol. 1, p. 13 dedek l. c. 1924. monumenta ecclesie strigoniensis. strigonii: typis descripsit gustavus buzárovits, vol. 3, pp. 473-475, 505 dl, df (hungarian national archives, archival documents of medieval hungary): 3448, 27829, 31242, 40902, 68845, 69670, 75835, 78505, 85252, 105741, 209593, 233634, 233635 loserth j. 1875. fontes rerum austriacarum. oesterreichische geschichts-quellen. königsaaler geschichts-quellen / domherr franz von prag. vol. 1: scriptores vol. 8 vienna: karl gerold’s sohn, cap. 4: pp. 568-570 nagy i. 1884. anjoukori oklevéltár / codex diplomaticus hungaricus andegavensis. budapest: magyar tudományos akadémia, vol. 4, pp. 219-223, 226-232, 252-255, 282-291, 341-343 nagy i. 1887. anjoukori oklevéltár / codex diplomaticus hungaricus andegavensis. budapest: magyar tudományos akadémia, vol. 5, pp. 66-78, 278-282 németh p. 1997. a középkori szabolcs megye települései. nyíregyháza: ethnica, pp. 39-40, 70, 72, 117-118, 171-172 pertz g. h. 1851. monumenta germaniae historica. scriptores. continuatio claustroneoburgensis v. hannoverae: impensis bibliopolii aulici hahniani, tomus 9, p. 736 piti f. 2007a. anjou-kori oklevéltár / documenta res hungaricas tempore regum andegavensium 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k.k. univers.-buchhandlung, p. 44 journal of environmental geography journal of environmental geography 10 (1–2), 11–21. doi: 10.1515/jengeo-2017-0002 issn: 2060-467x impacts of stone mining and crushing on stream characters and vegetation health of dwarka river basin of jharkhand and west bengal, eastern india swades pal1, indrajit mandal1* 1department of geography, university of gour banga, malda 732103, west bengal, india *corresponding author, e-mail: indrajitgeofarakka@gmail.com research article, received 13 january 2017, accepted 25 may 2017 abstract dwarka river basin (3882.71 km2) of eastern india in the chotonagpur plateau and gangetic plain is highly affected by stone mining and crushing generated dust. in the middle catchment of this basin, there are 239 stone mines and 982 stone crushing units. these produce approximately 258120 tons of dust every year and this dust enters into the river and coats the leaves of plants. on the one hand, this is aggrading in the stream bed, increasing sediment load, decreasing water quality, specifically increasing total dissolved solid, ph, water colour, and it also degrades the vegetation quality. vegetation quality is also degraded as indicated by decreasing of ndvi values (maximum ndvi in 1990 was 0.70 and in 2016 it was 0.48). considering all these issues, the present paper intends to identify dust vulnerable zones based on six major driving parameters and the impact of the dust on river morphology, water quality and vegetation quality in different vulnerable zones. weighted linear combination method (in arc gis environment) is used for compositing the selected parameters and deriving vulnerable zones. weight to the each parameter is assigned based on analytic hierarchy process, a semi quantitative method. according to the results, 579.64 km2 (14.93%) of the catchment area is very highly vulnerable: here 581 rivers have a length of 713 km and these riversare prone to high dust deposition, increased sediment load and water quality deterioration. keywords: dwarka river basin, stone mining, stone crushing, river bed aggradations, sediment load, water quality, vegetation health introduction stone crushing industry is an important industrial sector engaged in producing crushed stone of various sizes depending upon the requirement which acts as raw material for various construction activities such as construction of roads, highways, bridges, buildings, and canals etc. it is counted that there are over 12,000 stone crusher units in india (patil, 2001). in india, the stone crushing industry sector is estimated to have an annual turnover of >us$ 1 billion and 500,000 principally unskilled or semi skilled rural people engaged in this sector (cpcb, 2009). these stone crushers though socio-economically an important sector, give rise to substantial quantity of fine fugitive dust emissions which create health hazards to the workers as well as surrounding population by causing respiratory diseases. the dust is generated primarily due to size reduction and handling of the stones at various stages. the major sources of dust generation are the size reductions in the primary, secondary and tertiary crushers. in different stages the amount of dust production varies. the central pollution control board (cpcb, 2009) reported the proportion of dust contribution at different stages of crushing (see table 1). the fine-grained dust production depends on the type of the crusher and the parent rock. primary crushers produce 110% of fines, secondary crushers produce 5 – 25% fines, and tertiary crusher produce 5 – 30% fines. similarly limestone contains 20–25% of fines; sandstone contains 35–40% fines, whilst igneous and metamorphic rocks contain 10–30% fines (mitchell 2009). blatt and tracy (1997) analyzed the composition of stone dust emitting from a stone crusher unit. they documented that the chemical composition was sio2-72.04%; al2o3-14.42%; k2o-4.12%; na2o3.69%; cao-1.82%; feo3-1.22%; mgo0.71%; tio2-0.30%; p2o5-0.12% and mno2-0.05%. this proportion varies according to composition of the rock from which crushing is done. average dust contamination level in the atmosphere is 0.10 mg/m3 in usa (moran et al., 1994; tucker et al., 1995, iarc,1997; us epa, 1996). the actual area of the source of the dust generation is quite small (about 0.51 m2) at each source, but as the dust rises it spreads and typically the area in which it spreads is more than 10 to 15 times larger (cpcb, 2009) than the area of actual emission at about 3 to 8 m height. mining must be planned so that after the mining process the dumped land can be reclaimed by vegetation and agriculture. the problems of waste rock dumps become devastating to the landscape around mining areas (goretti, 1998; sarma, 2005). the dust adversely affects visibility, reduces growth of vegetation, agricultural crops and hampers aesthetics of the area as well as river system (cpcb, 2009). sharma and kumar (2016) pointed out that dust deposition on agricultural field reduces productivity of rice and carbohydrate content within the rice grain. such dust is one of the most visible, invasive, and potentially irritating impacts associated with quarrying, and its visibility often raises concerns that are not directly proportional to its impact on human health and 12 pal and mandal (2017) the environment (howard and cameron, 1998). it has noteworthy impact on landscape and biological communities of the earth (down, 1997; bell et al., 2001) and leads to ecosystem disturbance. natural plant communities get disturbed and the habitats become impoverished due to mining, presenting a very rigorous condition for plant growth (shivacoumar et al., 2006; mishra and kumari, 2008). the unscientific mining of minerals poses a serious threat to the environment, resulting in the reduction of forest cover, erosion of soil in a great scale, pollution of air, water and land and reduction in biodiversity (pandey and pandey, 2010; prasad et al., 2010; saha and padhy, 2011; unesco, 1998). most of the plants experience physiological alterations before morphological injury symptoms become visible on their leaves (liu and ding, 2008). rai et al. (2010) reveals that the foliar surface was an excellent receptor of atmospheric pollutants leading to a number of structural and functional changes. increasing dust concentration in atmosphere will raise the temperature state of the environment and hamper the ambient ecological condition (ziaul and pal, 2016). site conditions that affect the impact of dust generated during extraction of aggregate and dimension stone include rock properties, moisture, ambient air quality, air currents and prevailing winds, the size of the operation, proximity to population centres, and other nearby sources of dust (bell et al., 1977). drainage direction and volume both channelized or unchannelized form is also an important vector for spreading these effects in its surrounding. degree of drainage slope controls the dispersal rate of sediment and dust from the place of origin and pools and riffle condition, variability of discharge regulate persistence of materials within the channel or swiping off the same (sipos et al., 2014; nagy and kiss, 2016). dust concentrations, deposition rates, and potential impacts tend to decrease rapidly away from the source (howard and cameron, 1998). table 1 particulate emission factors for stone-processing operations. source: pollution data division of environment canada (2008) sources emission factors kg/10000kg production total particulate matter(tpm) pm10 pm2.5 drilling 0.000 800 0.000 040 0.000 002 primary crushing 0.005 800 0.000 290 0.000 017 secondary crushing 0.001 208 0.000 290 0.000 017 tertiary crushing 0.001 208 0.000 290 0.000 017 screening 0.004 286 0.000 420 0.000 124 conveying and handling 0.007 327 0.000 720 0.000 213 most of the previous studies mainly concentrated on impact of mining and crushing dust on vegetation and human health (pyatt and haywood, 1989; john and iqbal, 1992; grewal et al., 2001; prajapati and tripathi, 2008; rai et al., 2010; saha and padhy, 2011; sharma and kumar, 2016). but the present study intends to find out the impact of stone mines and stone crushing units on surrounding rivers specifically in terms of stone dust deposition within stream bed and water quality of the river. this study also aimed to find out the vulnerable zones to stone dust considering the fact that the region nearer to the stone mines and crushing units are more vulnerable to dust. although the dimension of contamination is multi furious like effect on human health, agricultural production, water quality, stream morphology etc. but concentration mainly is given on to the stream morphology, water quality and vegetation health in the dust affected areas. figure 1(a-d) shows the logic behind setting such objective. fig. 1 field evidences highlights the problems of stone dust (a) crushing of stone and admixing dust in the atmosphere (b) draining of heaped up dust to the river (c) deposition of dust in the channel bed and banks (d) thick dust layer to the tree leaves study area the dwarka river is a tributary of mayurakshi river. originating at kushpahari of santhal parganas in jharkhand it has been flowing through eastern chotonagpur plateau fringe area of jharkhand and west bengal, ultimately it joins the dwarka babla river near hizole wetland (88°4'12.93''e; 24°4'42.27''n) in murshidabad flood plain of west bengal (fig. 2). this basin area is covering an area of 3882.71 km2 with along its 156.54 km. long main channel and some major tributaries like brhamni, bamni, gambhira, borkunda, ghagar etc. it comprises a small portion of chotonagpur plateau fringe (santhal pargana upland) at its upper course (40% of the total basin area) and rarh plain (birbhum rarh); moribund deltaic west bengal (murshidabad plain) in the lower course. it lies to the north of river mayurakshi and to the south of river bansloi. two major faults lines namely rajmahal fault line (rfl) and gaibandha fault line (gfl) and one normal faults line are existing within the south west to north west part of the basin. there are two seismic points situated one at upper (sismicity hypocentral depth 25-70 km) and another is at the lower catchment (sismicity hypocentral depth more or less 25 km) of the dwarka river basin (fig. 3). http://en.wikipedia.org/wiki/santhal_parganas http://en.wikipedia.org/wiki/jharkhand http://en.wikipedia.org/wiki/murshidabad_district http://en.wikipedia.org/wiki/murshidabad_district impacts of stone mining and crushing on stream characters… 13 fig. 2 location of the studied dwarka river basin showing the drainage, stone mines and crushing sites geologically the upper part of the basin dates back to the deposition of dharwanian sedimentary followed by hercinian orogeny from cambrian to silurian period. the extreme eastern part of the upper basin is characterized by unclassified granitic gneiss with enclaves of metamorphic geomaterials. the middle catchment is mostly characterized by the deposition of lateritic soil and hard clays impregnated with caliche nodules. the platform of this region was set through the tectonic activities associated with tertiary epoch. the lower catchment is mostly characterized by recent alluvial deposition of alternative layers of sand, silt and clay attributed by alleviation river diversion, flooding and consequent shaping by twin action of bramhani (main tributary of dwarka) and dwarka river. the upper basin area of undulating well drained tract of chotonagpur fringe have fragile coarse lateritic soil containing siliceous matter, karoline, magnesium and iron oxide and sandy gravelly soil or gravelly soil with proximate rich pegmatite rock (let, 2012). elevation of the basin ranges from 14m to 497m, out of total basin area, 58.88% area lies below 76m asl maximum slope of this river basin is 5.76° in the isolated hillocks of upper and upper middle catchments of the basin. almost flat surface is found in the murshidabad plan region where drainage deranging is observed. total 2552 river units were identified with 3297.49 km length with seven orders hierarchy (strahler, 1964). distribution of stream frequency in different orders and their respective lengths is shown in table 2. average stream frequency and density are respectively 0.710 nos./km2 and 7.15 km./km2 administratively, the study region includes pakur and dumka districts of jharkhand and birbhum and murshidabad districts of west bengal. there are 16 cd blocks (kandi, khargram, berhampore, nabagram of murshidabad and nalhati, rampurhat, mahammadbazar, muyureshwar of birbhum), 3 urban centres (rampurhat, nalhati, kandi) within the study area. among these pakur, mhammadbazar region is rich with stone mining and crushing of stone. at present 239 numbers of stone mining units covering an area of 7.62 km2 are found at the middle catchment of the basin with 982 number of stone crusher units (fig. 2). most of the stone mining and stone crushing units are found at 40-110 m (asl) elevation in the plateau fringe area. fig.3 geological map of the studied catchment these soils are quite acidic, deficient in organic matter, poorly aggregated and possess low water holding capatable 2 order-wise number & length of the streams and some other morphometric aspect. method followed for calculating morphometric properties: stream order after strahler (1964), bifurcation ratio after schumm (1956), mean bifurcation ratio after strahler (1957), stream frequency after horton (1932) and drainage texture after horton (1945) stream order number of stream total length (km) bifurcation ratio mean bifurcation ratio stream frequency (df/km2) drainage texture first 2058 1521.65 3.998 0.710 7.15 second 349 638.18 5.896 third 115 468.55 3.034 fourth 22 207.56 5.227 fifth 4 111.59 5.500 sixth 3 272.83 1.333 seventh 1 77.12 3 total 2552 3297.49 14 pal and mandal (2017) city. transported secondary laterites and lateritic alluvium soils are found at the middle part of the basin (chakraborty, 1970). these lateriatic regolith is carried out by the main river and tributary system (jha, 1997; jha and kapat, 2003; jha and kapat, 2009). these lateritic mater fine silty alluvium soil is found at the lower catchment of the basin. the average rainfall is 15001600mm out of which 80% occurs during monsoon season (june to october). volume of runoff is also maximum in this time. bank full rivers found in this time. but upstream parts and streams of the upper catchment do not continue as bank full state even during peak monsoon time. rest periods of a year shows almost dry rivers in the upper catchment of a basin. wind direction highly varies seasonally. out of 365 days in a year 123 to 162 days wind comes from southern and south western directions, 53 to 71 days wind comes from north eastern direction, 31-52 days wind comes from eastern and south eastern direction. materials and methods method for evaluating vulnerability at first, six parameters have been taken into account as stated below for finding out stone dust vulnerability zones namely (1) stone crusher site (scd); (2) stone mines site (smd); (3) land use/land cover (luc) (4) vegetation health (ndvi); (5) surface slope (sa); (6) surface runoff (sro) stone mining and crusher units have been identified from google earth satellite imageries and gps survey where necessary. these are also identified from toposheets of survey of india (soi, 1972). these two layers are prime because the adjacent areas will be highly affected with stone dust (down and stocks, 1997; howard and cameron, 1998; bell et al., 2001; cpcb, 2009) and its effects will decrease away from these sites (bell et al., 1977). vegetation health was identified from landsat 8 (oli) satellite imageries (path/row 139/43; spatial resolution 30m.; date of acquisition 12th january 2016) using ndvi technique of rouse et al. (1973) (see equation 1). ndvi of all three phases is calculated for the month of januray. ndvi value indicating vegetation usually varies from 0-1. 1 indicates good quality canopy density. vegetation presence with greater density resists free spreading of dust from source points (howard and cameron, 1998; cpcb, 2009). land use types surrounding the stone mine and crushing centres is a prime factor of stone dust vulnerability. presence of human habitat, agricultural land and quality water bodies will up heave the degree of vulnerability (unesco, 1998; cpcb, 2009). size of the stone mine area and size of crusher unit can exert multiplier effects on environment. it is true that if size of these units increase, volume of dust production soars up. average surface slope is another important factor for draining subsided dusts through overland or channel flow. it is calculated from data received from suttle radar topographic mission (srtm) digital elevation model (dem) of united states geological survey (usgs) following the method of wentworth (1930). united states department of agriculture (usda, 1986) developed natural resources conservation service (nrcs) method for estimating runoff and developed equation for it (eq. 2), where, q is actual surface runoff in mm, p is rainfall in mm., ia is 0.4s/0.3s/0.2s/0.1s (season and climatic region specific) initial abstraction (mm) or losses of water before runoff begins by soil and vegetation (such as infiltration, orrainfallinterception by vegetation),0.3s is usually used for wet, 0.1s is used for dry seasons based on the pattern of ppt. and evaporation ratio.s is the potential maximum retention. s can be calculated using equation 3. for further details of this methods one can consult usda (1986).     ir band r band ndvi ir band r band    (eq.1) 2 ( ) a a p i q p i s     (eq. 2) 25400 254s cn   (eq. 3) scaling of the data layers scaling of data layers within their sub layers according to the magnitude of the sub classes and their influences toward the objective have been done using spatial analyst extension of arc gis environment, according to a 10 point scale. natural break method is assigned for reclass of the individual layers. one example can be illustrated regarding distribution of scale to the parameter. suppose stone crusher site is one of the parameters for measuring vulnerability of stone dust. this particular parameter is subdivided into 10 sub classes (distance classed) based on the proximity of crusher site. ten rank is given to the sub class very adjacent to the crusher units and descends toward outside distance considering the fact that area nearer to crushing site will be affected intensively. if any parameter controls such stone dust vulnerability in reverse direction (higher magnitude of sub class value indicates less influence to the vulnerability), 10 rank should be provided to the low sub class value (khatun and pal, 2016). such ranking helps all the data layers to be unidirectional. the influencing direction and scale consideration of the parameters has been shown in the table below (table 5). assignment of weight to the parameters the selected parameters applied in this study have not equal control on stone dust vulnerability. here, a specific weight is distributed to all parameters following the analytic hierarchy process (ahp) (saaty, 1980), a semi quantitative method for weight assignment (palaka and jai sankar, 2015). the ahp is a method to derive ratio scales from paired comparisons. the input can be obtained from subjective opinion such as satisfaction, feelings and preference. ahp allows some small inconsistency in judgment because humans are not always consistent (saaty, 1980). the ratio scales are derived from the principal impacts of stone mining and crushing on stream characters… 15 eigen vectors and the consistency index is derived from the principal eigen value. the relative importance values are determined with saaty’s 1–9 scale (table 3), where a score of 1 represents equal importance between the two themes, and a score of 9 indicates the ext reme importance of one theme compared to the other one (saaty, 1980). a matrix has been done for comparing the classes in order to achieve the priority. a pair wise comparison matrix is derived using saaty’s nine -point importance scale based on thematic layers used for zoning up the soil erosion susceptibility. because six parameters were applied in the study, the matrix has 6 x 6 cells (table 4). the diagonal elements of the matrix are always 1 and therefore it only needed to fill up the upper triangular matrix. based on the judgment value by comparing one thematic layer with other upper triangle matrix is filled. to fill the lower triangular matrix, only reciprocal values of the upper diagonal are calculated. if aij is the element of row i column j of the matrix, then the lower diagonal is filled using this formula: aij = 1/ aji. after the completion of the comparison matrix as weights for the selected parameters have received with 4 % check consistency level.. here maximum weight is found at stone crushing site (0.408) data layer followed by stone mine site (0.234) (table 5). compositing of parameters after assigning weight to the parameters, scaling of the parameters, weighted linear combination (wlc) method of eastman (2006) was used for compositing all the selected parameters and deriving vulnerability map using spatial analyst tool in arcgis environment. this function can be presented using the following formula. wlc= 1 n ij j j a w   (eq. 4) where, aij= i th rank of jth attribute; wj= weightage of j th attribute. fig.4 selected parameters as spatial data layers used for evaluating vulnerability to stone dust (a) distance map from stone crusher (b) distance map from stone mines (c) land use/land cover (lulc) (d) ndvi map (e) surface slope (f) surface runoff 16 pal and mandal (2017) table 5 modes of ranking of the intra sub class of parameters and distribution of priority based weightage parameters sub-class rank (highest rank: 10) weight of parameters stone crusher site (distance from crusher sites) natural breaks 1-10 0.408 stone mines site (distance from stone mines centre) natural breaks 1-10 0.234 land use/land cover (lulc) healthy vegetation 1 0.144 unhealthy vegetation 2 mix vegetation 3 lateritic upland 4 moist land 5 water body 6 settlement area 7 bare land 8 agricultural field 9 open field 10 vegetation health natural breaks 1-10 0.095 surface slope natural breaks 1-10 0.067 surface runoff natural breaks 1-10 0.051 this weighted linear combination has been done using raster calculator tool in arc gis environment. asproth et al. (1999), jiang and eastman (2000); mendes and motizuki (2001); araujo and macedo (2002); rinner and malczewski (2002); malczewski et al. (2003); makropoulos and butler (2005) are some of the successful users of wlc mainly for land use suitability. based on compositing of the raster layers vulnerability model is generated. equation 3 represents the wlc equation of the selected six parameters. sdvwlc= stone dust vulnerability on the basis of weighted linear combination: sdvwlc= (scd*0.408)+ (smd*0.234) + (luc*0.144)+ (ndvi*0.095)+ (sa*0.067) + (sro*0.051) – (eq. 4). methods for measuring stream bed aggradations from four different vulnerable zones, 81 sample tributaries have been taken into account and the sample distribution in different areal extent of vulnerable zones have been done following the rule of stratified random sampling. in all cases, the entire length of stream is not lying within a single zone. from each stream segment in respective zone, at least 5 cross sections have been carried out using dumpy level for understanding the channel bed aggradations. most of the rivers in this region is composed with bed rock and stone duct loosely deposited over the bed. therefore, while doing cross section, cross section over the bed rock and over the deposited dust surface have taken. gap between two cross section is majorly stone dust in most of the stream segments. along downstream course from the stone mining and crushing centres, mixing of stone dust and other sediments from other sources has become so complex and difficult to segregate only the volume of stone dust. zone wise average aggradations have been calculated for understanding the spatial variation. methods for measuring water quality stratified random sampling is carried out as done earlier from different vulnerable zones. altogether 81 samples we have collected within 1st to 15th july, 2016. total dissolved soild (tds), ph, water colour have measured from laboratory testing of the sample. atested results have been compared with bis (10500) standards of inland surface water (1991) both for measuring drinkability and irrigability. methods for detecting vegetation quality change according to nayar (1985), leaf area is the main component of tree canopies and the leaf area index gives quantitative data of the depth of canopies. forest canopies constitute the bulk of photo synthetically active foliage and biomass in forest ecosystems (lowman and wittman, 1996). therefore, any fluctuation in chlorophyll, carbohydrate or protein content of foliar tissues of dominant tree species of a forest can be treated as disturbances in table 3 saaty’s 1-9 scale of relative importance (saaty, 1980) scale 1 2 3 4 5 6 7 8 9 importance equal weak moderate moderate strong strong plus very strong very, very strong extreme table 4 pair wise comparison matrix for the applied parameters stone crusher site stone mines site land use land cover (lulc) vegetation health surface slope surface runoff stone crusher site 1 2 3 4 5 6 stone mines site 1/2 1 2 3 4 5 land use land cover (lulc) 1/3 1/2 1 2 3 4 vegetation health 1/4 1/3 1/2 1 2 3 surface slope 1/5 1/4 1/3 1/2 1 2 surface runoff 1/6 1/5 1/4 1/3 1/2 1 impacts of stone mining and crushing on stream characters… 17 overall growth of forest biomass. for detecting vegetation quality change, normalized difference vegetation index (ndvi) of rouse et al. (1973) is used for 1990, 2011 and 2016 from the landsat satellite imageries of the respective periods. three images representing different seasons (pre monsoon, post monsoon and winter) are taken into account for showing the average range of ndvi value. separately, season specific ndvi images are calculated for each season of the respective years and then average is carried out for showing yearly state. for 1990, landsat tm (resolution: 30m.; date of acquisition-05th january 1990 ) and for 2011 and 2016 landsat oli (spatial resolution: 30m.; date of acquisition respectively 11th january 2011and12 th january 2016images have been taken. usually ndvi value 0-1 indicates vegetation; value nearer to 1 depicts high quality vegetation or good canopy density. results and discussion based on weighted linear combination of the concerned parameters, vulnerability model has been prepared. wlc value ranges from 1.39-9.01 for entire basin. but it is assumed that effects of stone dust do not extend after a certain distance from the emitting units. therefore, instead of considering entire range of wlc value, only higher range of wlc value is considered (>5) and classified this range into four categories. it is found that out of total basin area altogether 579.64 km2. (14.93%) belongs to very high vulnerable categories and the high vulnerable category covers 09.06 of the catchment area. the first zone is highly affected by stone dust. streams of this region receive huge volume of dust both in form of aerosols and dust with drainage. number and length of the rivers under different vulnerable zones have been counted and measured thereafter. from this approach it is found that 581 river channels are situated in the very highly stone dust vulnerable zones carrying 713km length, 331river channel segments are found in the highly vulnerable zone with the length of 496km; 198river channels (323km) are situated on the moderately vulnerable zone and 113 stream channels covering a length 228 km is found in the low vulnerable zone. fig. 5 vulnerable zones and affected streams table 6 potential impact classes of stone dust and their respective area, stream association potential impact pixel count area ( km2) area (%) no. of strea ms strea m lengt h (km) 3.50-9.01 8240 579.64 14.93 581 713 3.00-3.50 4998 351.77 09.06 331 496 2.42-3.00 4732 332.74 08.57 198 323 1.39-2.42 5854 411.95 10.61 113 228 impacts of stone dusts on channel bed aggradations and sediment load this field measurement in the one hand helps a lot to understand the impacts of stone dust and on the other hand it also introspects that how far the vulnerability model is valid. it is assumed that if rate of channel bed aggradations is very high and water quality is transformed substantially validity of the model inferred. for successful completion of this work during field study 81 tributaries have been selected on the basis of stratified random sampling fig.6 river cross profile and stone dust deposition in (a) very high (b) high and (c) low vulnerable zones 18 pal and mandal (2017) from different vulnerability classes. twenty tributaries have been selected from very high vulnerable zone, 25 from highly, 20 from moderately and 16 from lowly vulnerable stone dust affected zones. from each stream at least 5 cross sections have been drawn to know the average situation of stream bed aggradations due to dust. in the very high vulnerable zone, depth of dust deposition ranges from 0.09 to 0.20 metre and average depth of dust deposition 0.125m range of depth of dust deposition on river bed in the highly vulnerable zone is 0.09 to 0.19 metre with an average of 0.096m. average depth of dust deposition on rivers within moderately and low vulnerable zones is 0.083 and 0.061 metres respectively (table 8). it is to be mentioned that channel segments away from crushing unit truly show only dust. but it is clear that dust decreased away from the emitting units. impacts on stream load characters most of the streams are over loaded with huge amount of dust especially those are located at very proximate region of mining and stone crushing centres. due to such conditions, thick dust is deposited over the channel bed. during monsoon time carrying capacity of the streams increases, thus they carry the loose materials. suspended load increases due to stone dust during early monsoon (june and july) because deposited dusts over surface drains to the river during initial period of over land flow and admixture with tributaries. suspended and bed load varies directly downstream from stone mine and crushing units. average suspended load is 15762g/m3during monsoon time in the very high vulnerable zone, followed by 12456 g/m3 in the highly vulnerable zone. in the low vulnerable zone, it is recorded that average load volume is 6782g/m3. which is low enough and in this area maximum proportion of it is contributed by eroded soil not by the dust. this information also supports the vulnerability models. studies also recorded that this volume of load decreases downstream with varying rate depending on the dust product ability of the mining and crushing centres, discharge volume of the rivers where these are in fluxed, slope of the region, nature of wind. here it should be mentioned that effect of this dusts exerts down slope. so the vulnerability zones indicated by the model do not exhibits uniform results even within a single vulnerability zone. in the upslope part around a mining or crushing centre is less affected because stream flow does not carry such dust in this situation. airborne dust mainly affects the upslope regions. most of the cases load is almost 3-7 times lesser than down slope regions. impact on water quality ph value as an indicator of water quality specifically neutrality of water reveals that in the very high vulnerable zone ph value of river water is above 9. huge influx of stone dust is principally responsible for such transformed water quality, in the highly vulnerable zone, ph value is 8-8.5 (table7). but in low vulnerable zones, ph value of the river water is 8.2 and it is near to normal. from this analysis it can be stated that both channel bed aggradations and water quality status is beyond normal situation in the very high and high vulnerable zones and therefore, this model can be treated as valid. total dissolved solid (tds) is another water quality parameter altered after contamination by dusts. in the highly vulnerable zones, tds value with an average of 2487mg/l. this value is high very adjacent stream segment to stone mine and crusher centres. this high value is beyond the permissible limit of both drinking (500mg/l) and irrigation (2250mg/l) as per bis (10500) standards of inland surface water (1991). in the less vulnerable zone, this tds value (1256mg/l) crossed permissible limit for drinkability but it is irrigable. water colour appeared as grey of black drain water according to degree of vulnerability. even the animals do not drink this water because of huge suspended particulate matters in water. repetitive supply of water to the agricultural field can heap up huge volume of dust to the field and can alter the basis texture and composition of the soil. aquatic environment specifically fishing is strongly affected in these segments. although these stream segments were not highly worth for fish availability and fishing, but during monsoon season, fishing was practiced. but due to alteration of such physico-chemical parameters, such ambient environment has become altered. impacts on vegetation quality the middle catchment of the dwarka river basin is highly affected due to the stone crushing and mining dust. vegetation coverage has been decreased rapidly due to the construction of a new mine and crushing sites. the effect of dust pollution on plants is observed in this study as it has reduced the quality of vegetation in study area. the average ndvi value of 1990 was 0.470, whilst in 2011 it dropped to 0.54 and finally it is reduced to 0.48 in 2016 (fig. 7a, 7b and 7c). this decline of ndvi since 1990 to 2016 focuses on degradation of forest quality. most of the forest in this area is dominated by shorea robusta and madhuca indica, two broad leaf vegetation species and these are highly sensitive to stone dust. table 7 sample tributaries and their characteristics in different vulnerable zones vulnerable class selected tributaries range of depth of dust deposition on river bed(m) average depth (m) ph avg. tds (mg/1) very high 10 0.08-0.22 0.128 9 2487 high 6 0.09-0.16 0.092 8-8.5 2321 moderately 5 0.03-0.08 0.074 8.2 (1543 less vulnerable 7 0.001-0.08 0.058 8.2 1256 impacts of stone mining and crushing on stream characters… 19 saha and padhy (2011) documented that high rate of dust deposition in the leaves decelerates rate of photosynthesis and food availability within the plant body and it causes weakening of vegetation health. during non monsoon time effects of dust becomes more prominent because of thick dust coating over leaves. in this time due to lack of rainfall, this thick dust coat becomes thicker. apart from dust effects, continuous emission of hot smoke from crushing unit in the vegetation contiguous area causes partial plant celldamage. apart from qualitative damage of vegetation, due to installation of stone mines and crushing unit within forest area it is also rapidly expunged. conclusions from the above analysis, it is found that out of the total above mentioned basin area, a 14.93% area is very highly potential for dust vulnerability. within this zone, 581 numbers of streams having a length of 713 km are found to be highly affected. channel bed aggradations, increasing sediment load within water, degradation of water quality beyond permissible limits are some evident effects of dust emissions and spreading. continuous deposition of such stone dust over vegetation causes qualitative degradation of vegetation as indicated by declining of ndvi values between 1990, 2011 and 2016. due to mining activities, removal of prestigious forest has been rapidly degrading. certainly, this fact is not solely responsible for deteriorating forest quality. coarse grain lateritite soil (chokraborty, 1970), and mass scale soil erosion (68t/ha/y) are another controlling factors for tree felling and degradation of vegetation (jha and kapat, 2009; pal, 2016). the formation of dust layer on plant body damage plant tissue which reduces rate of photosynthesis. dust particles emitted from stone crushing activity reduces the pigmentation in plant leaves (saha and padhy, 2011). dust fall on open land reduces its fertility of soil (cpcb, 2009). deposition of dust particles exerts stresses on plant which reduces productivity of plants. along with deterioration of forest environment, degradation of aquatic habitat is also vital issue. fishes and other species will be in stress state if high level dust contamination happens and turbidity level raises. fish prefers to avoid hypoxic waters and favours more highly oxygenated waters (breitburg, 2000). but such hypo-oxygenated condition happened in the extra admixing of dusts. rombough (1988) explained different species of fishes have different ability to tolerate low oxygen concentrations, depending on the natural change of dissolve oxygen concentration that fishes encounter in their preferred habitat. catfishes tolerate wide range of oxygen variation but can’t survive if oxygen comes 59% below ambient limit (randolph and clemenens, 1976). opinion taken from local fishermen who were once engaged with fishing activities emphatically opined that river character has been changed and fish is become almost rare in this altered condition. influx of dusts automatically enhances turbidity level in water. turbidity impinges on both the density and metabolism of the plant populations present in stream channels (wallen, 1951; aldridge et al., 1987). a fig.7 vegetation health (using ndvi) (a)1990 (b) 2011 (c) 2016 20 pal and mandal (2017) study by clavel and bouchard (1980) showed that the absorption of light energy by water is proportional to the concentration of suspended sediment. high level of turbidity in river segments adjacent to the stone mine and crushing centres influences first tropic level in same manner. cordone and kelley (1961) and decker et al. (1999) etc. found out the impact of channel morphology, sand mining, dredging on water quality specifically, turbidity, tds, temperature etc. and all these again exert negative impact on aquatic habitat. pal et al. (2016) also reported the huge reduction of fish availability in chandrabhaga river basin after inflowing huge particulate matter from plant. for energizing growing urban sector through supplying building materials, this sector is getting plenty of attentions to the concerned authorities and loss of forest issues is quite sacrificed. such situation is also explored in different parts of the country with variable intensities. pal et al. (2016) identified the effect of fly ash on chandrabhaga river of chotonagpur plateau fringe area. they identified that this river is highly affected by thick (>0.5m) dust deposition and as result simplification of unique topographic features and ecological deterioration. dinda (2014) worked on rupnarayan river and reported that due to aggradations of channel bed through fly ash fish influx is deduced significantly. saha and padhy (2011) highlighted how fly ash affected the growth of vegetation and vegetation quality of the rarh tract of eastern india. they clearly stated that due to such effect green pigment contents in forest leaves have reduced significantly. this similar condition is found in the present study area also. in long term environmental agenda, such trend is not good at all. in this paper, attention is paid for a few issues only as mentioned above but apart from all these, human health hazards is also another major emerging problem in this area. the labourers working in this sector are highly exposed to respiratory diseases. during field investigation, opinion of the labourers has been taken into account regarding their health hazard. dust generated from mining and crushing unit should be used for filling of abandoned mines, fertilizer preparation, road and rail way constructions. but for a successful project, it should be kept in mind that sectoral coordination in this regard is highly necessary. references aldridge, d.w., payne, b.s., miller, a.c.1987.the effects of intermittent exposure to suspended solids and turbulence on three species of freshwater mussels. environ pollut 45: 17–28. doi:10.1016/0269-7491(87)90013-3 araujo,c.c., macedo,a.b. 2002. multicriteria geologic data analysis for mineral favorability mapping: application to a metal sulphide mineralized area, ribeira valley metallogenic province brazil. nat. resour.res. 11: 29–43. asproth,v., holmberg,s.c., hakansson,a.1999. decision support for spatial planning and management of human settlements. in: international institute for advanced studies in systems research and cybernetics. in: lasker, g.e. 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the mediterranean region accounts for the larger proportion of human-caused fires in the world (95%) (leone et al., 2009). in most of european countries, forest fire outbreaks result from human activities without intention to provoke damage (i.e., they start by accident, negligent actions, or risk behavior) (tedim et al., 2015). the increase in the number of wildfire hazards in recent years has brought a combined results of the ever-larger droughts and all-pervading reporting (mockenhaupt, 2014), which has called forth the increased number of remedial methods in dealing with fires. wildfires have the unique characteristic due to the complex interdependencies that exist between humans and the forest sources of wildfire hazards. forests have always presented the crucial territory for agriculture, livelihood, hunting and forests and other natural environments have also played important roles in sustaining human well-being (clayton and opotow, 2003). climate change will have an effect on the patterns of wildfire risk and their distribution (nicholls and lucas, 2007). locally, wildfire consequences affect directly air quality, ecosystems and landscapes. secondary consequences can be traced when we examine the impact of fire hazards on water and soil quality. these can cause instant damage to vegetation and fauna and have direct and indirect impacts on soils through heat release and ash deposition, and contribute to postfire environmental degradation (vallejo and alloza, 2015). at the beginning of this century a large-scale flooding period and forest fires started this is why the european parliament had to adopt the “european parliament resolution on natural disasters (fires, droughts, and floods) environmental aspects (2005/2192(ini))”. to protect the forests throughout the eu is one of the most crucial actions of the eu forest action plan, in which the member states are invited to 32 szatmári et al. (2016) support forest fire prevention measures, restoration of forests after being damaged by natural disasters (tedim et al., 2015). there are two main periods in the year when forest fires pose a great risk in hungary. the first group of fire incidents is connected with the beginning of agricultural work (burning of fields and stubbles) which starts after the snow has thawed and the weather is characterised by the lack of precipitation between february and april. new plantations are usually prone to more extensive damage in these wildfires, while vegetation consisting of older trees is less endangered. the second group of forest fires occurs from june to september when the dry litterfloor of deciduous and coniferous forests fuels these fires in the hot, drought-stricken summer months. these incidents are mainly characteristic of the drier areas of bács-kiskun and csongrád counties on the great hungarian plane [1]. the increased frequency of forest fires observed in the past few decades is most likely to be caused by the more and more extreme climate (less precipitation, higher mean temperature, winters without sufficient snow covering), which ultimately leads to the drying out of plant litter. due to climate and vegetation circumstances, naturally induced forests fires are of no account (about 1%) in hungary. 99 % of forest fires are human induced (negligence or arson). most fires are induced by (adults’ and infants’) negligence and only a small proportion of fires are caused by arsonists [2]. in this study a severe wildfire and its impacts were assessed in case of a protected area of the kiskunság national park in hungary, which was partly burnt down in 2012. the aim was to support the professionals of the national park in their work to estimate damage effectively and properly as well as to plan, organize and implement restoration measures by providing remote sensing strategies and tools, i.e. methods of collecting, processing and analysing data (szatmári et al., 2014). study area the study area, the bugac juniper forest is located in the kiskunság sandland, in the danube-tisza interfluve (fig. 1). the no. vi protected area of the kiskunság national park (knp) is situated about 7 km north to the settlement of bugac. crescent-shaped sand dunes are the most characteristic features of the surface, they stretch out about 4 km long, and they may even reach 12-18 m height in this region. the majority of sand and loess found here are alluvial deposits of the paleo-danube. these deposits were shaped into sand dune lines by north-west winds in the pleistocene and holocene. the beginning of the holocene marked the anchor of these aeolian forms, but later in the boreal period the wind started to move them again (borsy, 1989). saline lakes were formed in the interdunal depressions (temesi, 1986). the predominant plant association of the area is the open perennial sand grassland. the extent of land cover is about 50%, it reaches its biggest diversity in spring and autumn, while the association usually dries out in summer. its environmental protection value makes the open perennial sand grassland a very important one (facsar, 1996); most of the endemic herbaceous plants of hungary can be found in this association (e.g. hungarian or sand fescue (festuca vaginata), different feather grass species (stipa sp.)). the natural multi-layer flora on the top and the southern slope of the sand dunes as well as steeper parts of the area is made up of juniper-poplars fig. 1 wildfire hazard of the hungarian counties and the location of the study area in bács-kiskun county, characterized by a considerable wildfire hazard environmental monitoring supported by aerial photography … 33 (festucetum vaginatae juniperetosum). the canopy layer consists of white poplars (populus alba) mainly, and sometimes grey poplars (populus canescens), the understorey layer consists of common junipers ( juniperus communis) as well as small groups of common hawthorns (crataegus monogyna) and blackthorns (prunus spinosa). there are several rare orchid species to be found in the forest floor such as the red hell eborine (cephalonthera rubra), the royal (epipactis etrorubens) and the bugac helleborine (epipactis bugacensis) (borhidi, 2003). english oaks (quercus robur) also mix into the closed canopy layer of the associations in the valleys and on the sand dune slopes. surface fires, when surface litter and other dead vegetal parts and smaller shrub burn have been common in this type of forest vegetation. they can develop in whole fire season. forest litter, needles, dead twigs and branches get totally dry in arid periods without rainfall and start easily burning as a consequence of negligently lighted fire [2]. on 29 april 2012, a fire broke out in the study area, and it was finally extinguished on 5 may 2012. the south-southeast winds took its smoke as far as the outskirts of the capital as is shown on satellite images (fig. 2). wildfire suppression was made difficult by embers in tree hollows that kept on smouldering for days, unfortunate soil conditions, and sudden gusts of the wind. it was a high-alert wildfire that flamed up numerous times until the afternoon of 1 may 2012, and more than a fifth of the protected area had burnt to the ground. both flora and fauna suffered considerable loss, for example, many protected reptiles and bird hatchlings fell victim to the fire. the hungarian state contributed to the restoration of the damaged vegetation by mobilising new work force who helped the employees of the national park clean up debris, plant saplings, and eradicate invasive plant species that started to spread aggressively in the burnt area. methods aerial photography remote sensing data were collected by equipping a cessna 172 with a high resolution aerial photography system (tobak et al., 2008a). out of the numerous advantages of the system, its cost efficiency (novák, 2015), and its operativity can be highlighted (tobak et al., 2008b). the fact that the system is easy to operate becomes particularly important in projects that investigate quickly changing phenomena (bakó, 2010). the central unit of the aerial photography system is a trimble aerial camera which is a 39megapixel model with a phaseone p45+ back wall, interchangeable 47 mm rgb and cir (color-infrared) imagery lenses, and various controllers. the camera system is supported by adequate power supply, gps tools to provide correct navigation, and a portable computer. the aero topol software of the system supports both the planning and navigational phases (tobak, 2013). in order to estimate damage as soon as possible, the study area was surveyed one month after the forest fire (7 june 2012), while monitoring its regeneration and the spread of invasive species happened one year later (1 july 2013). the same monitoring system and procedure were applied on both occasions. a precise flight route was planned before the aerial survey itself, which enabled us fig. 2 spread of the smoke of the 2012 bugac forest fire as depicted on a satellite image [3], common juniper with an old white poplar (populus alba) in the background and a part of the burnt area 34 szatmári et al. (2016) to prepare the geometric file of the flight rows and image centres based on the data of the study area borders given by the knp. it is the basic requirement of navigationand position-based aerial photography. the images were collected with a 60-70% overlap in the along track direction, and 20-30% in the cross track direction. these overlaps allowed the continuous cover of the study area as well as its spatial analysis (e,g. altimetry). a further important parameter of aerial photography is gsd (ground sample distance) which, in our case, was 20 cm (2012 survey) and 10 cm (2013 survey) respectively. 58 images were taken in 4 flight rows from altitudes of 1,400 m and 700 m in 2012, and 179 images were taken in 7 flight rows from the same altitudes in 2013 (fig. 3). data acquisition was followed by raw data – navigational and image – processing. the co-ordinates of the actual flight route and the aerial photo processing centre can be obtained in ascii format, which can be integrated into a geographical information system directly after being converted to the proper format. it means that we had 3 co-ordinates and one camera rotation angle (kappa) value, out of the 3 possible ones (omega-phi-kappa), per image at our disposal as initial exterior orientation parameters. this information is the input data for the aerial triangulation of the aerial photographs. the unit of the camera rotation angle was degree and the centre co-ordinates were recorded in the eov (unified national map projection) system in metres. creation of orthophotos by using small format aerial photography system, photographs can be taken at any time at any frequency, which provides precise orthophotos for further image classifications and analyses. the so-called block of aligned photos was prepared from individual photographic images. the auto detection of common points in the overlapping image parts and the initial parameters of the exterior orientation are used in this process. after aligning the images the software automatically starts detecting common points in the overlapping parts of the block, and creates a sparse 3d point cloud. in order to filter our gross geometric errors, a mesh is generated based on the sparse cloud. in order to match the model and the actual geographic space accurately, on site ground reference points are also needed. professionals of the knp placed 162 foil stripes in the study area so that they could be identified in the images too. the co-ordinates of these stripes were fixed with rtk gnss, and during data procession they served as gcps (ground control points) in the exterior orientation of the model. a homogeneous distribution of 8-9 gcps in the multi-overlapping image parts were enough in the total block of aligned photos. as a result, an orthomosaic (an orthophoto from rectified photos, with the same geometric resolution as the original aerial photos) is produced on the basis of the oriented aerial photo block of the whole study area. analysis of aerial photos the orthorectified rgb and cir images can be used in a wide range of studies. the common characteristic of these studies is that they require high spatial and temporal resolution and visible as well as near infrared spectral information. the detailed analysis of the processed data was done in the total of the study area. the applied methods can be categorised into manual, semi-automatic, and automatic methods based on the extent of the necessary intervention of the analysing process. in order to optimise fig. 3 flight plan and its parameters of the 2013 aerial survey campaign environmental monitoring supported by aerial photography … 35 the ratio of temporal and personal resources of the analysis to the expected quality and availability of the results, semi-automatic methods were employed primarily. manual analysis was employed to the visual separation and bordering of the parcels damaged to a varying extent. at this step it was important for the analyst of the data to be profoundly familiar with the study area, which was established by the on site fieldwork with the professionals of the knp and a thorough gps survey. remote sensing data were stored in raster format, and different image classification algorithms were run on them. we also tested the isodata technique, which automatically allocates the image elements to classes. in this case, identifying (labelling) classes happens afterwards. from the supervised classification methods, which demand bigger user intervention, the maximum likelihood algorithm was applied. in this classification method, classes were created on the basis of previously identified training sites with already known vegetable type and damage extent. on site field survey on site data collection took place on 9 april 2014, the state of the study area and the vegetation was surveyed. each parcel was categorised during the on site field survey, then the descriptive data of the surveyed objects were captured systematically in geographic information system. the type of the vegetation, the name of the most densely occurring invasive species, the extent of the species' spread were all categorised from 1 to 5. special data belonging to certain polygons were also captured, these data included information such as the newly planted poplars, the aging vegetation invasive species and their land cover rate in the study area invasive plants (or adversed introduced plants) are usually plant species which are not native to a specific location. invasive plant species usually do not have any special requirements, tolerate a wide range of environmental conditions, and have no natural controls therefore their pest-resistance is high. by adapting fast, they drive local native or indigenous species to (near) extinction. they have a tendency to spread aggressively and, as a result, they may seriously disrupt the native ecological system (sipos, 2004). the invasive species in the study area are as follows: tree of heaven or ailanthus (ailanthus altissima), false acacia or black locust (robinia pseudoacacia), common milkweed or silkweed (asclepias syriaca), wild black cherry (prunus serotina), non-native canadian (also known as american) poplar (populus x canadensis hybrids, populus x euramericana syn.), and black pine (pinus nigra). during the on site field survey 5 categories of invasive plant species were created on the basis of their density: 1. no presence in the parcel 2. 0-10% density in the parcel 3. 10-25% density in the parcel 4. 25-50% density in the parcel 5. over 50% density in the parcel surveying the vegetation of the study area the following types of vegetation were identified in the parcels of the study area when surveying vegetation and its general state: white poplars, junipers, white poplar-junipers, scots and black pines, false acacias, and open grasslands in some places. on the basis of the damage caused by the forest fire, intact and burnt parcels were identified. results extent of damage based on remote sensing data interpreting the pre-processed – orthorectified – aerial photographs meant manual delineating of parcels in the simplest case. in accordance with the expectations of the knp, this method was employed when surveying the damage to the non-native (introduced and purposefully planted) pine trees. on the basis of the forest maps 24% (202 ha) of the study area (a total of 835 ha) was classified as intact, 38 % (318 ha) as partly, and 38% (318 ha) as totally damaged (burnt) (fig. 5a, [4]). the results of the supervised (maximum likelihood) and the automatic (isodata) methods of the (semi-)automatic workflow are shown in a sample area of 11 ha, which represents the analysed categories of the whole study area. the supervised classification of the previously fixed training sites allocated 50% of the sample area as damaged (burnt), 30% as partly damaged, and 12% as intact. the rest of the study area, ca. 8%, was allocated as shadowed or open sandland (fig. 5b). the results of the isodata clustering run with 9 initial classes showed a more heterogeneous picture, at the same time, the border lines of the most damaged area was clearly seen here too. this method allocated 30% of the pixels to the damaged (burnt) class, 28% to the partly damaged, and 14% to the intact classes. the proportion of the shadow areas was bigger (21%) (fig. 5c). types of vegetation the study area (1748 ha) was covered by white poplars (622 ha, 34.8%), white poplar-junipers (488 ha, 27.3%), scots pines (307 ha, 17.1%), open grasslands (185 ha, 10.3%), junipers (115 ha, 6.4%), and false acacias (68 ha, 3.8%) two years after the wildfire (fig. 6). scots pines are found in the periphery, which may indicate that this type of vegetation may have a certain protecting role. on the basis of on site field data, more than half of the study area was damaged in the wildfire. juniper and scots pine associations were damaged the most extensively (fig. 7). there were no visible traces of wildfire damage in the open grassland associations, they had regenerated from seeds found in the soil. the burnt white poplar associations were sprouting which indicated their strong regeneration ability. the size of the sprouts were between 1-1.5 m. there were many aging stands in the forest which indicated the bad health state of the vegetation. the dead, burnt tree trunks left in the study area after the suppression of the wildfire were all decaying. 36 szatmári et al. (2016) fig. 6 location of different types of vegetation in the study area invasive species and the extent of their appearance the rehabilitation of the study area in the bugac juniper forest started in 2012. in the beginning, the dead and burnt wood pieces and logs were not removed from the study area, this process has been in progress since then. however, the transport of these tree remnants is not advantageous as disturbing the area makes it easier for invasive species to appear and spread. at the same time, processing and transporting the remnants is necessary to stop the appearance and rapid swarming of pests that endanger both the remaining and the newly growing vegetation. the spreading of the invasive plant species in the study area is rapid. the distribution of these species in the forest is as follows: 46% false acacia, 3% canadian poplar, 8% ailanthus, 2% black pine, 0.04% wild black cherry, and 18% common milkweed ( fig. 8). the most aggressively spreading invasive species is common milkweed. false acacia shows the greatest extent of spreading, this species strongly degrades the conservation value of this more strictly protected area. there were no signs of invasive species in the juniper associations, although it was damaged the most in the wildfire. figure 9 also shows that the invasive plant species appear in the periphery of the forest and in the open grassland associations. fig. 5 manual bordering of the damaged sites of varying damage extent (a) and their classification (b: supervised classification, c: isodata clustering) on the basis of aerial photos fig. 7 an aerial photograph showing the damage to juniper associations environmental monitoring supported by aerial photography … 37 fig. 8 the appearance of invasive species (ha) discussion and conclusions the extent of damage, the type and state of vegetation, and the extent of the invasive species' appearance were all categorised by processing and analysing aerial photos and on site field survey. databases were designed for further expansion, too, so that other types of data can be recorded and studied here in the future. the analysis of remote sensing data was aided by semi-automatic classification methods. our analyses and geoinformatic database help professionals regenerate the forest and stop the spreading of invasive plant species. in order to successfully regenerate vegetation, it is necessary to plant new stands. new planting of pine forests may be important because they may serve as a protecting belt around the inner area of the forest, and they may as well be buffer zones where the appearance of invasive species is not considerable. sprouts of white poplar associations in the bugac juniper forest must be controlled so that they will neither spread too much nor suppress junipers' spreading. it is also important to cut out invasive plant species continuously, and more parcels have to be cleared of the sprouts of false acacia and ailanthus. stopping common milkweed from spreading in open grasslands is another significant task, which is made more difficult by the fact that common milkweed spreads very aggressively in the area. their eradication is also made difficult by their mode of spreading: common milkweed reproduces both by seeds and rhizomes, and forms a colony or a long, thick line quickly crowding over other plants. further aerial photography and on site field survey are planned to follow the regeneration of the area and monitor the undesirable spread of invasive plant species. with our work we would like to contribute to the regeneration of one of the most visited sites of the kiskunság national park introduced in our study. acknowledgements we wish to express our thanks and gratitude to róbert aleksza, zoltán filotás and gergely folberth fromthe kiskunság national park, and csaba lestyán from the hungarian forest management bács-kiskun county government offices for their assistance in our work. fig. 9 invasive species and degree of invasion 38 szatmári et al. 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(capturing and processing of sfap cir aerial photos and their application in environmental assessments) iv. magyar földrajzi konferencia előadásai. 618 p. (in hungarian) tobak, z., szatmári, j., van leeuwen, b. 2008b. small format aerial photography – remote sensing data acquisition for environmental analysis. journal of environmental geography 1 (3-4), 21– 26. doi: 10.2478/v10326-012-0001-5 vallejo, v.r., alloza j.a. 2015. postfire ecosystem restoration. in: paton d., shroder j. f. (eds.): wildfire hazards, risks, and disasters. elsevier, 229– 246. doi: 10.1016/b978-0-12-4104341.00012-9 internet references: [1] http://goo.gl/tgiwcq [2] http://erdotuz.hu/forest-fires-in-hungary/ [3] http://goo.gl/mlnfdu [4] http://goo.gl/b3dmpx impact of urban land use on rainwater quality: case study in ilorin metropolis, nigeria journal of environmental geography 15 (1–4), 31–37. doi: 10.14232/jengeo-2022-44124 issn 2060-467x impact of urban land use on rainwater quality: case study in ilorin metropolis, nigeria toluwalope mubo agaja1*, david olaoluwa towobola1 1department of geography and environmental management, faculty of social sciences, university of ilorin, p.m.b. 1515, ilorin, nigeria, +2347032329906, +2348055916475 *corresponding author, email: agaja.tm@unilorin.edu.ng research article, received 25 july 2022, accepted 27 november 2022 abstract in ilorin being one of the fastest growing urban centres in nigeria, the physical transformation in land use and population density have effects on the rainwater quality. therefore, we aimed to analyse the relationship between physical and chemical properties of rainwater and urban land uses. a total of 15 rainwater samples were collected after two major rainfall events with an average duration of 20 minutes during the rainy season and analysed for 15 physical and chemical parameters namely: colour, conductivity, ph, total dissolved solids, turbidity, aluminium (al3+), copper (cu2+), iron (fe2+), nitrate (no3-), lead (pb2+), nickel (ni), sodium (na+), phosphorus (k+), zinc (zn2+) and sulphate (so42-). their mean, standard deviation, coefficient of variation, pearson correlation coefficient were used to interpret the results. the land use types in the area were agricultural, commercial, industrial, institutional and residential. the result revealed that the urban land uses and rainwater quality has a significant relationship in ilorin metropolis. agricultural, industrial and institutional land uses had the least significant effect on the quality of rainwater with the significant value (p<0.05) of 0.044, 0.035 and 0.014 respectively. in contrary, under residential land use the rainwater had poor quality (significant value: 0.724), while under commercial land use the rainwater had fairly good quality (0.585; p>0.05). the study concluded that the urban land uses has an impact on the rainwater quality. the study recommends that rainwater should be purified before drinking, and sustainable urbanization policies should be developed to prevent atmospheric pollution in ilorin metropolis. keywords: physical and chemical properties, rainwater, rainwater quality, urban land use introduction rainfall is a major component of the water cycle and it is responsible for the replenishment of the freshwater supply on the earth. the amount of rainfall varies with time and space (atedhor et al., 2019), therefore the rainfall situation of a place can be described by its intensity, duration and frequency. one of the problems posed by climate change is quantification, identification and ascertainment of rainfall and its implications on anthropogenic activities in order to assist in the development of measures of adaptation through relevant strategies for water resources management (de luis et al., 2000). rainfall is referred as the most important meteorological parameter that has the greatest impact on human activity. the principal characteristics of rainfall are its amount and frequency. rainfall amount is expressed as the rate of rainfall in millimetres per hour, while its frequency is expressed as the number of times it occurred in a given area, and it is expressed in days per year (okonkwo and mbajiorgu, 2010). rainwater can dissolve impurities from the air and cause contamination (e.g. heavy metals). heavy metals are majorly found in geological structures and minerals of the earth. in most cases, their concentrations in rainwater are within acceptable limits; yet, elevated levels of zinc and lead have sometimes been reported (atedhor et al., 2019). on the other hand, rainwater is often used as drinking water, especially in dry areas. the chemistry of drinking water commonly has been cited as an important factor in many diseases. these diseases are apparently related to contaminated drinking water by heavy metals. this could result from leaching from metallic roofs and storage tanks, or from atmospheric pollution (milovanovic, 2007). as reported by several researchers, rainwater can contain significant amount of pollutants such as heavy metals, nutrients and pathogens, as a result of various anthropogenic activities resulting from the actual land use type (gromaire-mertz et al., 1999; lye, 2002; zhu et al., 2004; evans et al., 2006; yufen et al., 2008). thus, in determining the end use and the potential success of potable use of rainwater in the study area, the possible problems associated with its quality need to be assessed. the interference of some elements with rainwater leads to changes in the properties of the collected rainwater (or drinking water). normally, the drinking contains magnesium, nitrate, calcium, manganese, sulphate, iron and gases such as carbon dioxide, oxygen and nitrogen. some of these elements are beneficial at certain levels (e.g., fluoride and chloride), while others, such as the heavy metals (e.g., lead, nickel, and arsenic) are toxic. these pollutants are in form of polycyclic aromatic hydrocarbons, sulphates, nitrates and dioxins, at diverse quantities (amodio et al., 2014). gaseous or solid pollutants move up in the atmosphere, they dislocate and https://doi.org/10.14232/jengeo-2022-44124 mailto:agaja.tm@unilorin.edu.ng 32 agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. affect the quality of air; these condense in the clouds and then in the form of rainfall they return to the surface (dami et al., 2012). with the increase in urban population, the land-use related challenges have also increase. most cities in subsaharan africa are being affected by increasing waste disposal and pollution problems, as a result of urban rapidly increasing population, widespread poverty, inadequate and weak local governance and limited financial resources (simmons et al., 2001). ilorin city, in nigeria, displays similar problems, especially because the city has expanded in size, and new types of various land uses (e.g. industrial, agricultural, institutional etc) appeared. its most worrisome effect is indiscriminate solid waste dumping: the waste is carried by surface overflow and contaminates water resources. besides, the rapid growth of real estate development, winning/mining of sand and wood collection within catchment areas of water bodies are also problematic in the city. ilorin metropolis is one of the fastest rising urban centres in nigeria, and there has been a huge increase in the population since it became the state capital in 1976. therefore, in 2022 the population of the metropolis was 1 million (un, 2022). the population growth rate of 2.67% is much higher than in other cities (national growth: 2.5%). the increase in population is a result of high natural growth rate and migration from rural to urban areas. these have caused in the emergence of new land use types within the state, that results in uncontrolled management and planning (agaja et al., 2020). rapid population growth drives other urban systems, such as pollution accumulation, urbanization and increased knowledge leading to increase in poor housing and sanitary conditions, and generation of waste. the physical transformation in land use and high population density are characteristic of ilorin, and as an emerging urban centre it effects the water quality of the city. this is monitored by the institute of water resources (iwr, 1997) as cited by fashae et al., (2017), whose findings revealed that different land use types are characterized by enormous potential of introducing pollutants into aquatic and atmospheric ecosystems, largely due to the diversity of human activities. urban land is characterised by areas of intensive use, where much of the land covered by artificial structures (ibrahim et al., 2014). urban areas include cities, towns, villages; strip developments along highways, transportation routes, power and communications facilities, and areas occupied by mills, shopping centres, industrial and commercial complexes and institutions that may, in some instances, be isolated from urban areas (anderson et al.,1976). rainwater quality refers to the, chemical, physical and biological characteristics of rainwater and its general composition. the quality of rainwater is a degree of the condition of rainwater relative to the requirements of one or more biotic species, and to any need of humans. it is frequently used by reference to a set of standards against which compliance can be assessed (nwajei, 2007). rainwater must possess the characteristics of being aesthetically wholesome, chemically tolerable and bacteriological safe before it meets up with the requirements of the world health organization as a potable water (atedhor et al., 2019). rainwater quality is determined by the composition of rainwater as affected by natural processes and human activities. rainwater quality depends on the constituents dissolved or contained within the rainwater. it is not possible to find completely pure rainwater in nature, since droplets of water already begin to dissolve a whole range of constituents in the atmosphere, such as airborne dust particles, gases and salt from sea spray (rain, 2008). in response to increasing unavailability of potable drinking water, the need to utilize rainwater as an alternative to surface water sources has increased. despite having some promising merits over other sources, rainwater use has often been rejected as a source of potable water supply on the grounds of its water quality concerns (meera and ahammed, 2006). impacts of urban land use on rainwater quality are multifaceted, diverse and wide ranging. on its transit through the landscape, water is left bare to the properties of the terrestrial surface which is a vital determining factor for both water quantity (sufficient freshwater supply for human and natural systems support) and quality (appropriate supply for an intended use). while land is used by humans in diverse ways to improve their life quality, most usages have caused undesirable effects on the environment. according to nuissl and siedentop (2021), many of the environmental difficulties which countries are undergoing are resulting from the growing rapidity of change in land use; and one of the critical facts about land use changes is that the effects may be long-lasting and sometimes unalterable. this submission is in line with nuissl and siedentop (2021) arguing that some changes are as a result of processes that are natural, but that we now know that anthropogenic activities are accountable for many of the environmental challenge s we are currently facing. built-up land use produces impermeable surfaces as a result of amplified development in the form of commercial and residential buildings (rooftops), driveways, highways and car parks etc.; these give increase to larger overflow, increasing the peril of canal dilapidation and other environmental consequences. ibrahim et al. (2014) argued that overflow from impervious surfaces such as car parks, heavily trafficked motorways etc. has consequences for the water cycle, both in terms of quality and q uantity. an extensive range of metallic, organic and inorganic pollutants may be detached from the road and land surfaces and occur at high concentrations in the runoff water, which is then carried into atmospheric water and water bodies. considering the size and environmental problems of ilorin metropolis in nigeria, this study aims (1) to assess the physical and chemical properties of rainwater in the prominent urban land use types; (2) to compare the results to the world health organization’s water quality standards; and (3) to analyse the relationship between various urban land uses and the physical and chemical properties of rainwater in the study area. agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. 33 materials and methods study area ilorin is the state capital of kwara state, which is located in north central nigeria (figure 1). the settlement was founded in 1967. it is positioned north of the equator, between the longitudes 4º20’ and 4º35’e; and latitudes 8º 30’ and 8º50’n (agaja et al., 2020). the city of ilorin occupies an area of about 468 km2, and it is located in a transition zone between the guinea savannah and forest regions. the city is about 500 km from abuja, the federal capital of nigeria, in the north and 300 km away from lagos in the south. ilorin has three local government areas, e.g. ilorin south, ilorin west and ilorin east (figure 1). the climate in ilorin metropolis belongs to the tropical continental with high temperature throughout the year (ifabiyi, 2000). average temperature ranges between 30-35ºc. the climate of the study area is characterized by tropical dry and wet seasons for about six months. the dry season begins in november and ends early march, while the wet season starts at about the end of march and lasts till the end of october. the total average of annual rainfall in ilorin is 1200 mm (agaja et al., 2020). in ilorin metropolis the drainage system has dendritic pattern. the most important river in the city is river asa, which flows in a south-north direction across the city. there are a few seasonal springs in or close to the floodplain (alao, 1982). the general elevation of ilorin metropolis varies from 273 to 364 m. the sobi hill is an isolated inselberg with its summit at about 394 m, and it is located towards the north of the western part of the city. ilorin metropolis has a welldissected landscape, with plateau-like surfaces shielded by laterite crust. the plateau-like surfaces are best detected at the adewole housing estate facing the sobi hill, and at the kwara state polytechnic facing to south. the lowest point (240-255 m) in the area is in the asa valley (alao, 1983). there are two extensive vegetation types in ilorin metropolis: forest and savannah. the savannah, especially guinea and sudan, are the major grains, tubers, grasses, and vegetable growing regions. vegetation contains scattered grasses and tall trees such as parkia biglobosa, actosonia digitata, butryspernum parkii, acacias, etc. (ifabiyi, 2000). ilorin metropolis is covered mainly by ferruginous tropical soils and crystalline acid soils. these soil types possess good potential for a large variety of crop production, thus modern farming methods are applied. the alluvial plains of river belts provide suitable conditions for arable farming for most part of the year (iroye, 2017). methods the rainwater samples were collected directly from the open sky during three major rainfall event with an average duration 20 minutes (table 1). the sampling sites were randomly selected by purposive random sampling. sterilized rainwater collectors were installed in open surfaces representing each urban land use types. the choices of the land uses are due to their prominence in the study area as well as the anthropogenic activities concentrated in such areas. the rainwater samplers were mounted 1.5 m above the ground to avoid rain splash. a total of 15 composite rainwater samples were collected (from 5 land use types and at 3 major rainfall events) the rainwater samples were labelled, cooled and transported immediately after collection to the university of ilorin biochemistry laboratory for laboratory analysis. fig. 1 ilorin metropolis is located in nigeria (a) kwara state (b). drainage system and rainwater sampling locations within the ilorin metropolis (c) 34 agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. a global positioning system (gps) receiver was used to capture the geographical coordinates of the 5 sampling locations. the selected locations were in the following prominent urban land use types: 1. agricultural – akerebiata 2. commercial – post office 3. industrial – asa dam 4. institutional – university of ilorin 5. residential – oke-odo the analysed physical and chemical parameters in the rainwater samples, their units and the methods of their respective analysis are shown in table 1. the physical and chemical data collected provided by the laboratory analysis were checked for quality, and computed using microsoft excel software and statistical package for social science (spss). inferential and descriptive statistical tools of mean, standard deviation, standard error of mean, coefficient of variation, percentage change, range, annual growth rate and pearson correlation coefficient were used in the analysis and interpretation of the results. results physicochemical properties of rainwater in ilorin metropolis the actual physical and chemical properties of rainwater based on three times repeated measurements in ilorin metropolis are presented in table 2. the average mean of ph, nickel and zinc were highest in institution land use with 9.2 mg/l, 0.061 mg/l and 0.165 mg/l respectively in the rainwater samples, while the lowest mean average in the institutional land use were conductivity, total dissolved solids and turbidity with values of 90 mg/l, 11 mg/l and 0.012 mg/l respectively. thus all parameters fall within the world health organization water quality standard, except for the total dissolved solids (tds) which was the highest (102 mg/l) at the commercial land use, but all values were within the world health organization water quality standard. although the amount of tds was less than the world health organization water quality standard, the impurities and particles in the rainwater could support the increase of physical and chemical parameters, if stored for a long period of time, which could lead to a majority of ill-health (salem et al., 2000). the high electric conductivity is because the rainwater has amassed various particles of dust, soil, carbon (iv) oxide, greenhouse gases and airborne aerosols that dissolve before deposition as a result of frequent and prolonged anthropogenic activities in the commercial land use (dami et al., 2012). in all the land use, aluminium and colour were all the same and fall within the who standard. the turbidity, aluminium, copper, lead, nickel and zinc values of the rainwater at all land uses had quite low values, often bellow the detection limit, therefore these parameters met the world health organization water quality standard with no exception of any land use (table 2 and figure 2).copper (0.21 mg/l), ph (7.2), iron (0.02 mg/l), phosphorus (0.38 mg/l), sulphate (36.4 mg/l) and zinc (0.056 mg/l) had lowest mean values in agricultural land use, and they are within the who standard of drinking water. the sulphate content of the rainwater was highest on institutional land use with a mean value of 47.2 mg/l, while agricultural land use had the least mean value of 36.4 mg/l. regarding the nitrate content of the rainwater, the values were below the world health organization water quality standard (table 2). in table 2, the mean iron content values were between 0.31 and 0.36 mg/l for institutional and industrial land uses, and they both exceeded the world health organization water quality standard of 0.3 mg/l for iron ions. this implies that the rainwater in both institutional and industrial land uses could be detrimental to the environment and health of the consumers, as a result of the vehicles and heavy-duty trucks plying the roads and the industrial activities being carried out. this is in line with igbinosa and aighewi (2017), reporting that iron exceeded the maximum acceptable concentration by the world health organization in all the rainwater samples that were collected for their research table 1 laboratory analysis of physical and chemical water quality s/n parameters laboratory methods unit 1 colour colorimetric tcu 2 electrical conductivity multimeter µs/cm 3 ph electrometric 4 total dissolved solids gravimetric mg/l 5 turbidity turbidity ntu 6 aluminium aas mg/l 7 copper aas mg/l 8 iron aas mg/l 9 lead aas mg/l 10 nickel aas mg/l 11 nitrate aas mg/l 12 phosphorus aas mg/l 13 sodium aas mg/l 14 sulphate aas mg/l 15 zinc aas mg/l agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. 35 relationship between urban land use types and rainwater quality in ilorin metropolis the results on the relationship between urban land use types and rainwater quality in ilorin metropolis showed that between these parameters there was a significant relationship at p-value <0.05. agricultural, industrial and institutional land uses had the least significant effect on the quality of rainwater with the significant value of 0.044, 0.035 and 0.014 respectively, which was less than 0.05 degree of freedom as shown in table 3. this implies that at institutional land use the rainwater quality was better than at other urban land use types, followed by industrial and agricultural land uses. on the other hand, residential land use had very poor rainwater quality with significant value of 0.724 when compared to the other urban land use types, while commercial land use had fairly good quality with 0.585, which were both above the degree of freedom of 0.05. this implies that institutional land use in ilorin metropolis contributes the least contaminants to the rainwater. this is as a result of very few anthropogenic activities being carried out within this land use type, as this contains mainly office buildings. the industrial land use in ilorin metropolis does not contribute so much to atmospheric pollution as it was expected, because ilorin is not a highly industrialized urban centre, as the release of industrial contaminants into the atmosphere is not prominent. the agricultural land use in ilorin metropolis also does not have much effects on the rainwater quality, because many of the agricultural practices carried out within ilorin metropolis are not mechanized, and have very low interaction with the environment. the commercial land use has significant effect on rainwater quality in ilorin metropolis, because many commercial activities are carried out within the metropolis. the major commercial activities are located in the central business districts which include the shopping centres and markets, located along major highways and access routes to ilorin metropolis. a bulk of junkyards, resorts, warehouses, banks, parking lots and driveways are located within the commercial land use type. these buildings and structures rely predominantly on the use of generators, as well as the intense use of automobiles which releases greenhouse gases and various dust particles into the atmosphere. this explains why the commercial land use contributes more to the contamination of rainwater. being the most prominent land use type, the residential land use has the most significant effect on rainwater in ilorin metropolis. the metropolis is an emerging urban centre, that is experiencing increase in urban population growth. this has resulted in the development of high-density housing structures, which has resulted in the destruction of natural ecosystems within the area. the rapid urbanization has increased pollution, poor sanitary conditions, waste generation and deforestation. most residential areas in ilorin metropolis have poor waste management, lack of access to portable drinking water, do not have adequate sewage disposal, and possess unsustainable urban structures. these, and many more have resulted in the release of contaminants into the atmosphere, which has increased the pollution of rainwater. this explains why the residential land use in ilorin metropolis has the poorest rainwater quality. this agrees with the result of atedhor et al. (2019), revealing that there was a distinct variation in the physical and table 2 urban land use types and measured rainwater parameters in ilorin metropolis parameters agricultural commercial industrial institutional residential mean standard deviation max min who standard colour (tcu) colourless colourless colourless colourless colourless conductivity (µs/cm ) 160 450 130 90 360 238 157.702 450 90 750 ph 7.2 8.5 7.7 9.2 7.4 8 0.833 9.2 7.2 7.0-8.5 tds (mg/l) 14 102 16 11 23 33.2 38.713 102 11 600 turbidity (ntu) 0.026 0.032 0.018 0.012 0.03 0.0236 0.008 0.032 0.012 0.5 aluminium (mg/l) 0.001 0.001 0.001 0.001 0.001 0.001 0 0.001 0.001 0.2 copper (mg/l) 0.021 0.053 0.026 0.048 0.056 0.0408 0.016 0.056 0.021 1 iron (mg/l) 0.2 0.25 0.36 0.31 0.27 0.278 0.060 0.36 0.2 3 lead (mg/l) 0 0 0 0 0 0 0 0 0 0.05 nickel (mg/l) 0.02 0.012 0.01 0.061 0.022 0.025 0.020 0.061 0.01 0.1 nitrate (mg/l) 31.6 30.9 37 31.7 28.4 31.92 3.137 37 28.4 50 phosphorus (mg/l) 0.38 0.41 0.46 0.44 0.42 0.422 0.030 0.46 0.38 20 sodium (mg/l) 0.58 0.49 0.32 0.33 0.37 0.418 0.113 0.58 0.32 50 sulphate (mg/l) 36.4 41.8 49.2 42.2 44.5 42.82 4.641 49.2 36.4 250 zinc (mg/l) 0.056 0.141 0.065 0.165 0.068 0.099 0.0502 0.165 0.056 3 36 agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. chemical properties of rainwater among different urban land use types and locations within their study area. they also established that the variations in the rainwater quality is not only the result of the atmospheric cleansing role of rainfall, but other factors, such as wind profile and atmospheric stagnation also determines the concentration of atmospheric pollutants. discussions it is important to note, that the lesser the quantity of the physical and chemical parameters present in the rainwater, the better the quality of the rainwater. the study discovered that institutional land use has the least contaminated rainwater, followed by industrial land use, then agricultural land use, commercial land use and lastly residential land use (institutional land use has significant value of 0.014, industrial has significant value of 0.035 and agricultural land use has significant value of 0.044, which are all less than 0.05 degree of freedom). on the other hand, commercial land use has significant value of 0.585, while residential land use has significant value of 0.724, which are both greater than 0.05 degree of freedom (igbinosa and aighewi, 2017; atedhor et al., 2019). the residential area covers 52%, commercial covers 19%, institutional covers 12% while other mi xed urban or built-up land covers the remaining 17% of the study area. the period between 2006 and 2020 witnessed a steady physical expansion of ilorin. the area of megacity increased by 17.48%, while the dense vegetation reduced by 5.73%, vegetation of farm-land reduced by 9.46%, the land use area of rock outcrop also reduced by 2.34%, and the water body have not increased neither reduced. this implies that annual growth rate of settlement in ilorin is 126%, while the dense vegetation reduced by 41%, vegetation of farmland reduced by 68%, the land use area of rock outcrop also reduced by 17% and the water body neither increased or reduced. the growth in the settlement area, resulted in the increase of anthropogenic activities in ilorin metropolis, which made atmospheric pollution more prominent. this released more contaminants into the atmosphere thereby resulting in poor rainwater quality. fig. 2 rainwater quality parameters on different urban land uses in the study area table 3 urban land use types and rainwater quality relationship in ilorin metropolis agricultural commercial industrial institutional residential agricultural pearson correlation 1 .971** .987** .968** .989** sig. (2-tailed) .000 .000 .000 .000 n 14 14 14 14 14 commercial pearson correlation .971** 1 .935** .897** .986** sig. (2-tailed) .000 .000 .000 .000 n 14 14 14 14 14 industrial pearson correlation .987** .935** 1 .995** .954** sig. (2-tailed) .000 .000 .000 .000 n 14 14 14 14 14 institutional pearson correlation .968** .897** .995** 1 .921** sig. (2-tailed) .000 .000 .000 .000 n 14 14 14 14 14 residential pearson correlation .989** .986** .954** .921** 1 sig. (2-tailed) .000 .000 .000 .000 n 14 14 14 14 14 **. correlation is significant at the 0.05 level 0 100 200 300 400 500 600 700 agricultural commercial industrial institutional residential who m e a su re d q u a n ti ty ( e .g . m g /l ) urban land use conductivity ph tds turbidity aluminium copper iron lead nickel nitrate phosphorus sodium agaja and towobola 2022 / journal of environmental geography 15 (1–4), 31–37. 37 conclusions and recommendations based on the results of this study, most tested physicochemical parameters met the world health organization’s water quality standards, with the exception of iron in the industrial and institutional land uses, where the concentrations exceeded the 3.0 mg/l limit value. the study discovered that institutional land use has the least contaminated rainwater, followed by industrial land use, then agricultural land use, commercial land use and lastly residential land use. there is a significant relationship between the prominent urban land use types of commercial, agricultural, industrial, residential, institutional land uses and rainwater quality in ilorin metropolis. the study recommends the full enforcement of atmospheric pollution control legislations within ilorin metropolis which will ensure that organizations, people, and groups that carryout activities that are causes of air pollution are reduced. furthermore, the collection and further usage of the rainwater in the commercial areas should be recommended, as here the water has much better quality, whereas in other parts of the city, especially in the residential and business areas care should be taken when using the water for human purposes. references agaja, t. m., adeleke, e. a., adeniyi, e. e., afolayan, p. t. 2020. the assessment of deforestation impact towards microclimate and environment in ilorin, nigeria. geosfera indonesia, 5(3), 301–317. doi : 10.19184/geosi.v5i3.16874 alao, d. 1983. geology and engineering properties of laterites from ilorin, nigeria. engineering geology, 19(2), 111–118. doi: 10.1016/0013-7952(83)90029-7 amodio, m., catino, s., dambruoso, p. r., de gennaro, g., di gilio, a. 2014. atmospheric deposition: sampling procedures, analytical methods and main recent findings from the scientific literature. journal of advanced meteorology, vol. 2014, article id 161730, 27 pages. doi: 10.1155/2014/161730 anderson, j. r., hardy, e. e., roach, j. t., witmer, r. e. 1976. a land use and land cover classification system for use with remote sensor data. united states geological survey circular 671. united states government printing office, washington, dc. doi: 10.3133/pp964 atedhor, g. o., ayeni a. o., aiyeki, j. a. 2019. spatio-temporal variation of the physicochemical properties of rainwater in benin city, nigeria. journal of the cameroon academy of sciences, 14(3), 205–218, doi: 10.4314/jcas.v14i3.4 dami, a., ayuba, h. k., amukali, o. 2012. effects of gas flaring and oil spillage on rainwater collected for drinking in okpai and beneku, delta state, nigeria. global journal of human-social science, 12(1), 25–29. online available at https://socialscienceresearch.org/index.php/gjhss/article/vie w/450 de luis, m., ravenlos, j., conzalez-hidalgo, j. c., sanchez j. r., cortina, j. 2000. spatial analysis of rainfall trends in the region of valencia, east spain. international journal of climatology, 20(12), 1451–1469. doi: 10.1002/10970088(200010)20:12<1451::aid-joc547>3.0.co;2-0 evans, c. a., coombes p. j., dunstan, r. h. 2006. wind, rain and bacteria: the effect of weather on the microbial composition of roof harvested rainwater. water research, 40(1), 37–44. doi: 10.1016/j.watres.2005.10.034 fashae, o., ayomanor, r., orimoogunje, o. 2017. land use dynamics and surface water quality in a typical urban centre of southwestern, nigeria. analele universitățiii din oradea, seria relații internaționale și studii europene, 27(1). 98–107. onilne available at https://geografie-uoradea.ro/reviste/ anale/art/2017-1/10.auog_724_adeola.pdf gromaire-mertz, m. c., garnaud, s., gonzalez, a., chebbo, g. 1999. characterization of urban runoff pollution in paris. water science and technology, 39, (2),1–8 doi: 10.1016/s02731223(99)00002-5 ibrahim, r. b., bako, a. i., raheem, w. m., abdulyekeen, a. o. 2014. appraisal of urbanization trends in ilorin, nigeria. journal of sustainable development in africa, 16(8), 313-319. online available at https://jsd-africa.com/jsda/vol16no8winter14b/pdf/appraisal of urbanization trends in ilorin.raheem wasiu mayowa.pdf ifabiyi, i. p., jimoh, h. i. 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(2009) pp. 5-14 the environmental history of fenékpuszta with a special attention to the climate and precipitation of the last 2000 years sümegi, p. 1,2 –törőcsik, t. 1 – jakab, g. 3 – gulyás, s. 1 pomázi, p. 1 majkut, p. 1 – páll, g. d. 1 – persaits, g. 1 – bodor, e. 4 1university of szeged department of geology and paleontology, h-6722 szeged egyetem utca 2-6, 2institue of archeology, hungarian academy of sciences, h-1014 budapest úri utca 49, 3sámuel tessedik college of the agriculture szent istván university, h-5540 szarvas szabadság út 1-3, 4hungarian geological institute, h1143 budapest stefánia utca 14. abstract this work presents the details of a multidisciplinary palaeoecological and geoarcheological study on the sedimentary sequences, including 2 undisturbed cores of the little balaton situated in the western part of lake balaton in central europe. the application of quaternary palaeoecological analysis to peat and lacustrine deposits enables to identify long-term environmental changes in aquatic and terrestrial ecosystems. the principal aims were to shed light onto how former human societies and culture shaped and altered their natural environment on the one hand. furthermore, to reconstruct the once existing environmental conditions within the framework of the natural evolution of the vegetation, soil, fauna and the catchment basin for the times preceding written historical records via the application of sedimentological, geochemical, isotope geochemical, palynological, macrobotanical, malacological and microfaunal analytical methods and approaches. introduction this work presents the details of a multidisciplinary palaeoecological and geoarcheological study on the sedimentary sequences, including 2 undisturbed cores of the little balaton situated in the western part of lake balaton in central europe (fig. 1). the application of quaternary palaeoecological analysis to peat and lacustrine deposits enables to identify long-term environmental changes in aquatic ecosystems. the composition of aquatic plant and animal communities is largely influenced by the hydrological conditions prevailing in the basin harboring them. the principal aims were to shed light onto how former human societies and culture shaped and altered their natural environment on the one hand. furthermore, to reconstruct the once existing environmental conditions within the framework of the natural evolution of the vegetation, soil, fauna and the catchment basin for the times preceding written historical records via the application of sedimentological, geochemical, isotope geochemical, palynological, macrobotanical, malaco-logical and microfaunal analytical methods and approaches. in the course of an international archaeologicalresearch, the cooperation with the archaeological institution of the university of leipzig and the institute of archeology hungarian academy of sciences opened up the possibility to implement an environmental historical study in the western part of the balaton region in relation to the fenékpuszta settlement forming a part of modern keszthely. fig. 1. 3d model of the study area with the sampling sites the entire record goes back in time to the pleistocene/holocene transition, but this article mainly focuses on environmental events and conditions related to the settlement and its activities in the migration period. special attention was paid to the records of the 4th-5th and the 8th centuries ad. this is justified by the fact that numerous historical interpretations published recently (györffy – zólyomi 1996, rácz 2008) presented speculations about draughts and famines leading to a collapse of the local avar empire, based on interpretations of data from iceland and western europe, but lacking regional environmental historical records from the area of the carpathian basin itself. material and methods for a complex environmental historical evaluation, the model and analytical system of birks and birks (1980) 6 sümegi et al. joeg ii/3-4 was adopted in our work. (table 1, fig. 2). to gain an overview of the subsurface geology and to highlight sites for undisturbed core retrieval about 20 probe cores were taken in the area of fenékpuszta. this was later on complemented by two parallel cores taken by a modified russian head corer (sümegi 2001) yielding overlapping undisturbed core samples from the infilled lacustrine basin of the kis-balaton near fenékpuszta (fig. 1). after transportation to the laboratory, the cores were cut lengthwise for various analyses; the sections for palaeobotanical and geochemical analyses were stored at 4°c in accordance with the international standards. the samples submitted to lithological analyses were identical with the ones used for the palaeobotanical, macrobotanical, malacological and radiocarbon analyses. for the macroscopic description of the samples and the preparation of the lithological column the internationally accepted system of troels-smith (1955) was adopted. the core was divided into 1-4 cm samples. to gain information on the chronology, 13 samples of plant macrofossils were subjected to ams (accelerator mass spectrometry) radiocarbon analyses in the radiocarbon lab of poznan, poland. in order to allow comparison with other archaeological data, the raw dates were converted to calendric ages using the calpal calibration programme, and the most recent calpal2007 hulu calibration curve. the original dates (14c) are indicated as uncal bp, while the calibrated dates are indicated as cal bc. the organic and carbonate content of the samples were determined by dean’s (1974) loi method. the inorganic content was further analyzed using the sequential extraction method. the so-called sequential extraction method of dániel (2004) with a long established history in the analysis of geochemical composition of lacustrine sediments was adopted in our work. from the full procedure the step of water extraction for unsepatable 1. an overview of the methods of investigations implemented on the two undisturbed cores (n: 46º 42.621’ and e: 17 º 14.048) with references describing the methods core sedimentological and geochemical analyses pollen and microcharcoal analyses macrobotanical and micro-zoological analyses mollusc analyses 14c analyses sümegi, 2001 troels-smith, 1955; dean, 1974; dániel, 2004 stockmarr, 1971; clark, 1982 jakab-sümegi, 2004 sümegi, 2004 ams method core name subsamples subsamples subsamples subsamples valcum i. and ii. 79 85 85 35 70 13 fig. 2. palaeoenvironmental analyses of fenékpuszta (kis-balaton) cores joeg ii/3-4 the environmental history of fenékpuszta with a special attention to the climate and precipitation of the last 2000 years 7 rated samples was sufficient to suit our analytical needs as it was shown by previous works (dániel 2004), the most important palaeohydrological and palaeoecological data originates from water extraction samples. elements of na, k, ca, mg, fe were determined using a perkinelmer 100 aas. sediment samples of 1 cm3 were taken from the core at 1-4cm intervals for pollen and macrobotanical analysis using a volumetric sampler. for the extraction and description of macrofossils a modified version of the qlcma technique (semi-quantitative quadrat and leafcount macrofossil analysis technique) of jakab et al. 2004 was adopted. for the extraction of pollen grains a modified version of the method of stockmarr (1971) was adopted. a lycopodium spore tablet of known volume (13911 spores per tablet) was added to all samples to give a desirable ratio for pollen to exotic spike to work out pollen concentrations. a minimum count of 500 grains per sample (excluding exotics) was made in order to ensure a statistically significant sample size. charcoal abundances were determinated using the point count method (clark 1982). mollusc shells were collected from 2 to 4 cm thick subsamples taken at regular intervals throughout the core. following the palaeoecological classifications of sümegi (2004), the aquatic malacofauna was divided into two groups: species demanding steady water inundantion (ditch group) and species tolerant to periodic water supply (slum group). terrestrial fauna was grouped as follows: water bank (hygrophilous), mesophilous, xerophilous, cold-resistant, intermediate, thermophilous, open habitat preferring, ecoton habitat preferring and woodland habitat preferring species. malacological record was also classified according to the recent geographical distribution of the species, following sümegi (2001) and on the basis of palaeoclimatological indicator roles. results from all analyses are plotted against depth using the psimpoll programme (bennett 1992). the study site lake balaton is the largest lake in central europe, with a modern open water area of 593 km2. the lake basin has a maximum length of 77 km, and a width of 8-14 km with a mean water depth of only 3-4 m. the area of the little balaton is located west of the modern open water system in a separate neotectonic catchment basin forming an extensive marshland today. based on historical maps of the first and second austrian military survey the area of the little balaton used to be a part of the larger unregulated lake system in historical times preceding the 19th century regulations. the neotectonic basin of the little balaton is located between the peninsula of fenékpuszta, the zalavár geological ridge and somogy hills. the zalavár ridge and the neck of the fenékpuszta peninsula are composed of pannonian and pliocene deposits overlain by late pleistocene loess. the area of the referred catchment basin is about 50 km2. our samples were taken in a small embayment located on the northern part of the catchment basin known as the fenékpuszta embayment. this area was infilled as a result of natural vegetation succession of peatlands during the holocene. this region lies on the boundary of the moderately cool–moderately wet (köppens cf) and the moderately cool–moderately dry climatic zones (köppens bs). the mean annual temperature is 9.8 ºc. the mean temperature of the growth season is around 15.5-16 ºc. the rate of annual precipitation is around 700 mm, 440 mm of which falls during the growth season. the climatic conditions of the region are favorable for forestry primarily. nevertheless, these endowments enable the cultivation of less heat demanding species. the region is part of the saladiense regarding vegetation geography; the most common forest associations are oak-hornbeam forests (querco robori-carpinetum), sessile oak-hornbeam forests (querco petraeae-carpinetum), oak-ash-elm gallery woods (querco-ulmetum), and willow-poplar gallery woods (salicetum albae-fragilis). the natural shrub level is dominated by white cinquefoil (potentilla alba), vetches (vicia cassubica, v. oroboides), large red deadnettle (lamium orvala), cyclamen (cyclamen purpurascens), prostrate rock-rose (fumana procumbens), fescues (festuca vaginata, f. rupicola). higher ridges are predominantly covered by brown forest soils (accounting for about two-thirds of the area), hosting arables, vineyards and hornbeam-oak forests in about even proportions. the soils of the catchment basin areas are hydromphic covered with gallery woods, meadows and pastures. the region is characterized by a flora typical for the preillyricum between the illyricum phytogeographical province of the western balkans and the pannonian region covering most of modern-day hungary. numerous illyric, submediterranean and alpine floral elements thrive in the undergrowth of oak forests. large stands of alder trees (alnus glutinosa) dot the wet meadows with a constantly high water table. the open areas around the mires are utilised as arables and pastures. archaeology of fenékpuszta the area is characterised by a mix of cultures from an archaeological point of view. as shown by the archaeological data, the area was continually inhabited from the second half of the neolithic. it is by no means accidental as the fenékpuszta isthmus, just like the máriaasszony island in vörs belonging to the southern part of lake balaton, was the most important crosspoints of lake 8 sümegi et al. joeg ii/3-4 balaton between the pointbars of balatonberény which could have existed as early as the antiquity (sági 1968, müller 1987). the area was populated during the neolithic (m. virág 1996) copper and bronze ages by representatives of various cultural groups (see bondár 1996, horváth 1996). the area was also inhabited in the iron age by members of the halstatt culture of the early iron age as well as the celts in the late iron age. the celts managed to survive in the area at the time of the beginning of the roman conquest in the 1st century ad (müller 1996). the romans appearing in this area in the imperial age thus settled in a highly modified so-called cultural rather than natural landscape. based on archaeological data, a fortress was built where the roads running from aquile to aquincum and to sirmium and augusta treverorum traversing diagonally transdanubia met. the size of the fortress is astonishing with 44 round towers ranging 377 x 358 m fortress square meters. the building was constructed of ca. 87 000 m3 stones. the walls were 2.6 m thick and 10 m high with possibly 4 gates. traces of 22 edifices have turned-up so far which adjusted to the by-pass joining the north-southern gates. out of these rise the more than 1000m2 big horreum and the building of the early christian basilica. based on the size and the edifices of the forests, a significant population engaged in advanced farming must have inhabited the area of fenékpuszta in the imperial age. according to the archaeological and historical data gathered until now, the fortress was destroyed by ostrogoths in october 455 ad. after its reconstruction, the fortress might have been the seat of thiudimer, the eastern-gothic king, as the cemetery of the eastern gothic people migrating to the east-roman empire was excavated just south of the fortress (straub 2002). the ownership of the examined area is problematic in the following half century. there was an assumption that it belonged to odoaker, the italian king then the suebians of the danube spread their authority up to this region. according to another concept, a part of the leaving eastern goths stayed and could have owned the fortress then the lombards extended their authority over this area. following the pullout of the lombards in 568, the previous population could have lived on in fenékpuszta, though they might have added new folk elements to their existed ones as more changes can be examined in the archaeological material. namely, parts of the jewellery, following the avar conquest after 568, have no local antecedents and the new funerary practices and objects were in sharp contrast with the poor funerary adornments dated before 568. parallel with this event, an early christian basilica was erected with three apses. similar type of construction works were recorded only in northern italy and in the balkans for the same period. the leaders of the area established their cemetery near the horreum after the second half of the 6th century. the cemeteries, which were not looted, were started to be used around 568 and funerals took place here up to 630. at present, 460 graves are known from this period in the locality of keszthely-fenékpuszta. most of the new findings are related to the avars. in spite of this fact, we cannot take the factual avar population’s presence into account as probably a mixture of local population could have been formed here who paid tax to the avars. however, the standpoint of researchers about the consistency of population is diverse. according to károly sági, the population of the fortress consisted of late antique and western germanic population. lászló barkóczi referred to the burying rituals with stones as a custom of the local survival population. istván bóna assumes the presence of a byzantine or lombard ruling class with byzantine elements. there are also theories of alamans and franks escaping to be under the avars’ authority. moreover, the research has lately started to take the elements of romanised christians into account escaping from the southern part of noricum and pannonia. the research named this mixed ethnical group as the keszthely culture. the ruling class and the followers of keszthely culture disappeared after the siege of the fortress in 630, though burying sparsely happened in the commonality cemetery until the end of the 7th century a.d. following the decline and fall of the avar empire, the karoling age (szőke 1996) came in the life of fenékpuszta which existed as long as the hungarian conquest and the occupation of the area in transdanubia, so for a century or so. based on the one hand on medieval archaeological findings, the medieval church and cemetery of pusztaszentegyház as well as on on its dated bell originated from 1509, it was the place of a medieval village called fenék (= bottom). this settlement has been noted first in 1347 and last in 1594 (vándor 1996). at this time the fortress might not have been used and by the end of the turkish empire, the area had become deserted. in the 18th century, the population moved to keszthely. the land, together with fenékpuszta, was bought by the festetics family in 1739. in the times came, they influenced the image of the area and established horsebreeder premises, carpenter and ship building plants. they have probably used the stones of the roman fortress too, although the walls of it are also marked on an austrian military map made in 1782 (timár et al. 2006). at the same time, on the maps made in 1792 and in 1805, the fortress is not marked anymore. according to this, the total demolition of it might have happened between 1782 and 1792, so at the end of the 18th century. joeg ii/3-4 the environmental history of fenékpuszta with a special attention to the climate and precipitation of the last 2000 years 9 results based on the collective evaluation of biotic and abiotic records a fairly complete history of the geological and environmental evolution of the area could have been drawn. fluvial sands giving the bedrock of our cores must have formed about 11 kys ago, at the end of the pleistocene (sümegi et al. 2008). this level is characterised by the presence of valvata piscinalis, a moving-water gastropod as well as the smallest calcium and magnesium content and the most essential inorganic material content. the observed minima of water soluble elements seems to be congruent with the picture drawn from the evaluation of other records; i.e. the deposition of fluvial sediments and non-weathered silicates to the incipient neotectonic basin. this incipient catchment basin must have been fringed by pine woodland with stands of birch and reed. the fluvial deposits are overlain by a slightly layered, pink lacustrine layer with highly varying carbonate content and spots of volcanic ash. this horizon marks the evolution of a larger lake system within the forming catchment basin as also marked by a maximum of ca and mg in the deposits among water soluble elements. the inferred 3 m deep, mesotrophic lake rich in carbonate must have existed in the area from the beginning of the early holocene until the end of early bronze age (20th-21st century bc). the retrieved lacustrine deposits yielded a significant amount of stonewort algae as well as parts of floating read grass and shells of lymnaea peregra f. ovate and valvata piscinalis marking the presence of a well-lit, deep, calcareous lake in the area for the referred period. the former coniferous woodland was replaced by a deciduous woodland dominated by oak, elm and hazel during the referred period as seen from the pollen record. macrobotanical remains talk about the emergence of a wide belt of reeds, bulrushes and sedges on the shore before the gallery woodland. from a depth of 106 cm up to the surface, representing the periods of the early bronze age to the middle ages a general decrease in the water level is inferred compared to the previous stage of the lake. nevertheless, three distinct periods or cycles could have been identified when the continuous deposition of organic materials in a marshland setting halted and was exchanged by lacustrine sedimentation within the framework of an eutrophic lake (fig. 2). this stage marked the end of the open lake system, and although these periodic water level rises significantly influenced the deposition of calcareous lacustrine muds into the basin, conditions like in the modern open lake system of balaton never returned to the area afterwards. cycle 1. after the formation of an early bronze age peat layer, in the period corresponding to the end of the early bronze age, beginning of the middle bronze age (beginning of the 19th century bc), a dynamic but short rise of the water level occurred in the examined area based on the macrobotanical and malacological findings leading to the formation of a shallow eutrophic lake in the basin (table 2). at the end of the same period, and in the second part of the middle bronze age peat deposition resumed leading to the formation of floating marsh and a closed peat layer at this part of kis-balaton. then in the late bronze age, due to a rise of the water level, the peat formation halted again resulting in the deposition of a thin layer of lacustrine marls over the previous peat sequence. cycle 2: following the late bronze age, in the early iron age, a subsequent peat deposition could have been inferred (between the 8th and 2nd century bc) followed by another rise in the water level and the formation of another short shallow lacustrine phase. the high correlation between the observed concentrations of water soluble mg, na, k and the accumulated peat horizons is by no means surprising, as these elements tend to accumulate in aquatic plants. around the end of the late bronze age, beginning of the iron age, besides the remains of plants and molluscs preferring a lacustrine environment, a drop in the amount of the referred elements could have been observed marking a phase of inundation (between 66-62 cm), followed by another stage of peat deposition between the depth of 62-48 cm. in the iron age, between the 8th and 2nd century b.c., a more pronounced inundation of the basin could have been inferred from a dynamic decrease of water soluble elements. conversely, at the beginning of the imperial age, peat formation was dominant as seen from a gradual increase in mg, na and k in the deposits. 10 sümegi et al. joeg ii/3-4 cycle 3: following the deposition of lacustrine marls in the late iron age another peat formation started from the imperial age. the imperial age also marked the end of these natural cycles of lake-marshland stages and conditions characteristic of a marshland seem to have stabilized for the forthcoming periods in the area. the speed of sediment accumulation also decreased probably because a part of the surficial peat deposits suffered incipient pedogenesis. from the shift observable in the geochemistry a short period of inundation could have been inferred at the end of the imperial age and at the beginning of the migration period. this might have been the outcome of a general increase in precipitation on the one hand. but this is not the only factor we must take into account while finding an explanation to the short rise in the water table within the catchment basin. as shown by written records romans have devised a drainpipe system in the 3rd century ad, with which the level of lake balaton was kept artificially low. the rise in the water level at the time of the migration period, could be attributed to the fact that these drainpipes constructed by the romans might have been clogged in the lack of general cleaning and maintenance. nevertheless, the inferred rise in the water table in our area is congruent with the transformations observed in a more distant catchment basin of nagybárkány located in the ne part of hungary as well for the same period (fig. 3). here a general increase in the precipitation as inferred from pollen data and a rise in the water table could have been postulated (jakab – sümegi 2005). similar changes were table 2. results of radiocarbon analysis cm bp +/cal bp +/cal bc/ad +/lab code 20-21 610 30 605 37 1345 ad 37 poz-20847 22-23 1050 30 966 23 984 ad 23 poz-20915 25-26 1235 30 1175 61 775 ad 61 poz-20840 29-30 1355 30 1290 13 660 ad 13 poz-20888 30-31 1400 30 1318 18 632 ad 18 poz-20838 31-32 1480 30 1366 16 584 ad 26 poz-28408 34-35 1875 30 1813 48 137 ad 48 poz-21486 36-37 2110 30 2084 43 134 bc 43 poz-20889 40-41 2750 30 2840 35 890 bc 35 poz-28407 52-53 3050 35 3279 50 1329 bc 50 poz-20848 76-77 3485 35 3768 61 1818 bc 51 poz-20849 96-97 3540 35 3816 61 1866 bc 61 poz-20850 104-105 3670 35 4008 61 2058 bc 61 poz-20890 fig. 3. comparison of the fenékpuszta and nagybárkány (see sümegi et al. 2009) investigations joeg ii/3-4 the environmental history of fenékpuszta with a special attention to the climate and precipitation of the last 2000 years 11 observable on the core section corresponding to the imperial age from a nearby lacustrine-marshland system at lake baláta (jakab – sümegi 2007) in the south western part of transdanubia, which enjoys similar climatic endowments as the site of fenékpuszta. many historians put forth numerous postulations about long-lasting draughts and severe consequences on the population of the carpathian basin for the period of great migrations (györffy – zólyomi 1996, rácz 2008). some of them went as far as stating that the main push factor for migration of eastern european tribes was the general aridity of the climate resulting in long-lasting draughts. the cornerstone of these statements was the observed low water level of the caspian lake during the referred period followed by a subsequent inundation of the coastal harbors (györffy – zólyomi 1996, rácz 2008). the inferred paleoclimatological reconstructions of these authors raise significant problems from several points and are challenged by modern paleoecological data: 1./ fluctuations in the water table of the caspian lake are not related to fluctuations in the precipitation to the eurasian steppes forest steppe areas because the drainage of this lake system is located in the highland region of the caucasus and central asia on the one hand, as well as the taiga belt on the north (rodionov 1994). thus making inferences about the precipitation of the steppes based on fluctuations of the water level of the caspian sea is not accurate. 2./ the majority of the harbours, inundated later on from the end of the antiquity and the early migration period, are located in a tectonically highly active area in the northern part of the caspian sea. plus, at the edge of the volga delta. consequently, we have two geological forces working in the referred area which might have resulted in an inundation of the coastal areas and harbours independently of fluctuations in precipitation (aladin – plotnikov 2000). the continuous sinking of the northern bed of the caspian lake (inland sea) is of striking importance here (degens – paluska 1979). although this process causes annually only a few millimetres of change, within hundreds of years it might have lead to even a one meter rise of the water level in the coastal areas. the other force is related to the sediment carrying capacity of the river volga leading to a rapid infilling of the accommodation space in the coastal areas, which again might be a cause of water level increase there. 3./ according to the data retrieved by geologists, climatologists and geographers (mayev et al. 1983) working in the area, the water level of the caspian sea was extremely high at the end of the antiquity and the beginning of the migration period, because the water balance of this inland sea is influenced by not only the precipitation coming through the rivers which is a significant factor, but also the temperatures around the inland sea (klige – myagkov 1992). according to the data we have at hand, the development of a cooler phase in the central-asian area can be inferred at the beginning of the migration period. so it is not surprising that a quite high water level was reconstructed for the caspian lake in this period which is in sharp contrast with the statement given by the referred hungarian historians. at the same time, the data prove that in the course of the past 2000 years, quite significant changes have happened in the water level of the caspian lake. but these changes had connections primarily to the development of temperature and only secondly to the precipitation coming through the rivers (budyko et al. 1988). thus water level changes in the referred lake system are related to fluctuations in the precipitation of central asia, the caucasian highlands and the eurasian taiga belt, as well as the temperature fluctuations of central asia. thus the climatic and demographic models made by historians for the area of central europe for the period of great migrations seem to be in sharp contrast with the paleoecological information for the area of the caspian sea and those of the carpathian basin as well and as such need adverse correction. returning to the environmental history of keszthely-fenékpuszta in kis-balaton, the beginning of the migration period, which was characterized by a rise in the water level with highly ambiguous causes, was followed by another dynamic increase in the water soluble elements of mg, na, k marking peat formation. peat formation initiating during the imperial age continued during the migration period as well. nevertheless pedogenesis was also observable in these peat horizons. thus from the period of the imperial age and the subsequent period of great migrations the emergence of a stable marshland could have been inferred for the northern parts of the fenékpuszta isthmus. these conditions survived until the closure of the middle ages in this part of the kis-balaton. this peat formation might have been continuous from the time of the great migrations. but the element content of the near-surface layers could have been dynamically modified by hydromorphic soil formation which took place in the middle ages. this hampered the reconstruction of water level fluctuations in the area from the end of the migration period onwards. besides precipitation, various forms of agricultural activities could have been captured in our record as well. based on the pollen content a widespread cultivation of corn and extensive animal husbandry could have been inferred for the area of the fenékpuszta isthmus from the middle bronze age. yet, the most powerful human influences are related to the imperial age. from the end of the iron age the proportion of open-area loving plants, weeds, gramineae, artemisia increased signifi12 sümegi et al. joeg ii/3-4 cantly, together with numerous plants marking intensive horticulture such as juglans, vitis. as for the pollen results, cultivation of juglans, vitis and triticum survived until the 7th century ad based on radiocarbon dates. on the basis of this, we can conclude that agricultural activities with sub-mediterranean characteristics of cereal production and horticulture developed at the end of the iron age and the beginning of the imperial age in this region. communities having proper production experiences and engaged in the referred form of agriculture populated the study area until the second half of the 7th century after the migration period (figs. 2, 3). the pollen of juglans and vitis vanished from the section while the pollen of cerealia, though in a subordinate ration, but survived from the second half of the 7th century. according to this, an extremely dynamic change in the economy of the examined area can be assumed. the referred communities, having farming experiences with submediterranean characteristics, and establishing quite dynamic environmental changes as well as farming records in the imperial age and operating a well developed farming system at the end of the late iron age, might have been driven out of the examined area. based on radiocarbon data these transformations must have taken place between 604 and 673 ad (95% probability). summary of findings based on the collective evaluation of biotic and abiotic records a fairly complete history of the geological and environmental evolution of the area could have been drawn (table 2). in the first phase at about 10-11 kya, a neo-tectonic basin developed giving the foundation of the emerging lacustrine system. the infilling of this catchment basin initiated even at this stage leading to the deposition of fluvial sands. the juvenile lake was surrounded by a coniferous woodland with stands of birch on the shores and an extensive reed belt. at around 10 ky bc a mesotrophic lake emerged and the gallery forest fringing the lake and dominated by pine, birch and hazel were replaced by woodlands dominated by hazel, elm and oak. the rate of silting-up was generally low during this period enabling the preservation of lacustrine conditions for a long time. the infilling of the basin was more rapid during the second half of the neolithic as well as the copper age. this was the period when pollen taxa marking plant cultivation, stock farming first appeared in our catchment basin, and fluctuations in the concentrations refer to the emergence of increased agricultural activities in the surroundings of the fenékpuszta isthmus from this time onwards. lacustrine conditions were preserved till the beginning of the bronze age yet pronounced transformations in the surrounding vegetation could have been inferred attributable to human activities. based on the long preservation of lacustrine conditions we may assume that the subsidence of the basin and the development of the general accommodation space must have kept pace with the rate of deposition for about 7000 years. this system and the fragile equilibrium was broken as a consequence of intensive human activities from the neolithic onwards. as a result of these events, three major cycles could have been identified in the area in the form of alternating marshland and lacustrine conditions from the middle bronze age to the middle ages. the alternating shifts among these stages are related to the natural succession of the marshland and resulted in distinct periods of lowstand and highstand in the basin. the first lowstand is observable at the end of the early bronze age and at the beginning of the middle bronze age, followed by a significant rise in the water level during the middle bronze age. the second cycle evolved during the late bronze age and iron age also characterized by successive lowstand and highstand conditions. the third cycle is connected to the period of the late iron age and imperial age. this third cycle is of outstanding importance in understanding the environmental history of the period of great migrations. in this third cycle peat formation seem to have stabilized following an eutrophic lacustrine stage creating a stable marshland which survived from the imperial age through the migration period up to the middle ages. besides peat formation, soil formation also took place in equilibrium creating marshland hydromorphic soils. at the end of the late iron age and the beginning of the imperial era one of the most essential agricultural economies evolved, a submediterranean type of crop cultivation and horticulture of wine and walnut. this form of agriculture appeared around 0 ad lasted until the 7th century ad in the area. thus roman type submediterranean agricultural activities must have characterized the area during the migration period as well. from the 7th century ad onwards there is a marked change in the pollen record, implying the abandonment of this former submediterranean type of agriculture and the establishment of agricultural activities based on mainly stock farming during the 8-9th centuries ad. data indicating resumed horticultural activities and crop cultivation could be inferred from the 10-11th centuries onwards in the area. temperature and precipitation conditions of the last 2000 years as it can be seen on the climate reconstructions prepared on the basis of paleoecological data (fig. 3), the first 400 years following the birth of christ was characterized by temperatures above the average values for the past 2000 joeg ii/3-4 the environmental history of fenékpuszta with a special attention to the climate and precipitation of the last 2000 years 13 years. then in the 5th and 6th centuries a pronounced cooling could have been inferred, which was followed by a warmer period again with temperatures higher than the average for about 500 years in the carpathian basin. fluctuations in precipitation for the same period are characterized by much higher amplitudes than those inferred for the temperature. in the first 200 years precipitation was around the average of the past two millennia. the 3rd and 4th centuries ad are characterized by higher precipitation values with rates returning to near average in the 5th century. another period of higher precipitation follows spanning the interval from the 6th to the 8th centuries. if we compare these findings with records of grape, walnut and cereal production characterizing a submediterranean type agricultural economies in the area (fig. 3), it can be clearly observed that the presence or absence of these plants in layers from the middle ages and the migration period is independent of climatic fluctuations and are largely related to the production experiences of the referred societies. water level fluctuations inferred from sedimentological and geochemical proxies talk about a different story (fig. 3) according to sedimentological results, a highstand characterizing the iron age was followed by a continuous lowstand. the geochemical data is somewhat congruent with this picture with some minor differences. the iron age highstand is clearly observable in both records, but the general lowstand following was interrupted by a short phase of highstand between the 5th and 7th centuries ad in accordance with higher inferred precipitation rates. according to our findings, lake level fluctuations inferred for the area of the kis-balaton can be correlated with those of the alpine lakes (magny 2003), while the evolution of the temperature record seems to be correlated with the fluctuations (holzhauser et al. 2005) of alpine glaciers. to sum up in one sentence, the climatic and environmental evolution of our site seems to follow that observed in the eastern alps for the past 2000 years. thus making inferences about the climate of this region based on data from central asia is by no means accurate. acknowledgements this research was financed by the project managed by orsolya tamáska heinrich, for which the authors 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(eds.) évezredek üzenete a láp világából. kaposvár-zalaegerszeg: somogy és zala megyei múzeumok igazgatóságai. 22-33 shoreline change analysis of the eastern coast of ghana between 1991 and 2020 journal of environmental geography 16 (1–4), 11–21. doi: 10.14232/jengeo-2023-44339 issn 2060-467x shoreline change analysis of the eastern coast of ghana between 1991 and 2020 dzifa adimle puplampu1, khiddir iddris1, victor alorbu1, jonathan otumfuor asante1, judges laar takaman1, alex barimah owusu1* 1remote sensing and gis laboratory, department of geography and resource development, university of ghana legon. po box lg 59, legon. phone: 0540238420 *corresponding author, email: abowusu@ug.edu.gh research article, received 22 december 2022, accepted 7 march 2023 abstract the eastern coastline of ghana is facing intense natural and anthropogenic disturbances, which pose a serious threat to the coastal community, ecosystem, and livelihoods. this study assessed the shoreline changes occurring along the eastern coast of ghana stretching 149 km from laloi lagoon west of prampram to aflao, ghana. the study utilizes satellite images from landsat 4tm, landsat 7 etm+, and landsat 8 oli taken between 1991 and 2020. data pre-processing techniques using envi 5.3 included calibration, layer stacking, mosaicking, and supervised classification. post-classification shorelines were extracted using arcgis 10.7, and the dsas tool was used to determine the rate of change over the 29-year period. the results showed that the coastline experienced an average erosion rate of 9 m/y and a maximum rate of 24 m/y, however, the accretion rate (3 m/y) was much lower, reflecting general coastline retreat. thus, some 25 coastal communities are highly exposed to shoreline erosion. sustaining the coastal area may require coastline re-engineering interventions. this study recommends continuous monitoring of the shorelines to ensure the protection of livelihoods. implementation of both hard engineering and ecosystem-based adaptation strategies may be required to achieve holistic results toward sustainable coastal management. keywords: shoreline change, remote sensing, coastal vulnerability, coastal erosion, coastal accretion introduction globally, coastal zones are facing intense natural and anthropogenic disturbances related to sea level rise, coastal erosion, sand winning, and depletion of mangroves, which poses numerous threats to coastal regions (appeaning addo et al., 2011; ipcc, 2022). the threat to coastal ecosystems and coastal livelihoods has increased the awareness to accelerate efforts to assess, monitor and mitigate coastal stressors (zhang, 2010). monitoring spatial and temporal changes in coastal settings is one of the initiatives that can help understand the spatial distribution of erosion hazards and predict their rate and their spatiotemporal changes. the shoreline is defined as the location of the landwater interface at any given time (gens, 2010). shoreline change is a highly dynamic process that serves as a predictor of coastal erosion and accretion. globally, coastal areas have lost 28,000 km2 and gained 14,000 km2 of coastal land between the period of 1984 and 2015 (mentaschi et al., 2018). this translates into the net loss of 14,000 km2 of coastal lands for human and terrestrial habitats. luijendijk et al. (2018) using satellite imagery between the period of 1984 and 2016 show that 31% of the world’s beaches are sandy. out of this proportion, 24% are eroding at rates of 0.5 m/yr while 28% are accreting and 48% are stable. shoreline erosion, coastal inundation, and coastal resource degradation are among the possible risks that ghana's coastal communities are facing. climate change, rapid urbanization, and accompanying anthropogenic beach modifications intensify shoreline erosion and accretion (ekow, 2015; appeaning addo, 2015). ghana's coastline is approximately 550 kilometers long below the 30 m contour above sea level, which makes it prone to erosion (ekow, 2015). the seashore is split into three sections based on their geomorphological characteristics. all of these have been identified to be vulnerable due to the frequency of coastal erosion, tidal waves, and sea level rise coupled with anthropogenic factors. the eastern coast, in particular, has suffered a variety of geomorphological events (appeaning addo et al., 2008; jayson-quashigah et al., 2021). these events are especially effective, due to the low-lying lands, unconsolidated sediments, shoreline orientation, and sediment starvation (littoral) from the volta river after the construction of the akosombo hydroelectric dam. the effects of the dam have exposed the entire coast from laloi lagoon west of prampram to aflao to increased rates of erosion, tidal waves, inundation, and floods, especially from atorkor to keta (ly, 1980; appeaning addo et al., 2011; anthony et al., 2016). the eastern portion of the coast is predicted to lose between 2 and 7 million m3 of sand per year owing to continual erosion (appeaning addo et al., 2011; evadzi et al., 2017). as a result, most coastal settlements have been displaced, commercial operations have been destroyed (ships no longer dock at keta), educational, https://doi.org/10.14232/jengeo-2023-44339 mailto:abowusu@ug.edu.gh 12 puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. residential, and historical structures have been lost, and the lagoon basin has been silted. other notable issues resulting from climate change (sea level rise) include the loss of agricultural land (erosion and salinization), reduced soil fertility, which results in poor yields, as well as a decrease in fish catch (both lagoon and marine), and perennial flooding of farms, which causes migration (anthony et al., 2016). even though interventions have been made, such as the keta sea defense project (gldd, 2001), the dzitaatorkor sea defence work, and the ada sea defense project to stabilize the shoreline with breakwater, these efforts have not yielded the needed results as coastal communities still suffer devastating events (jaysonquashigah et al., 2021). oceanographers, geologists, and geomorphologists have developed diverse techniques to monitor shorelines using maps and aerial photographs (kawakubo, et al., 2011). although these methods are effective, they are expensive and time-consuming. on the other hand, recent advances in remote sensing techniques, allow researchers to process large-scale data effectively in a low-cost manner (berlanga-robles and ruiz-luna, 2002). this is because multispectral satellites capture digital pictures in many spectral bands, including the near-infrared, where the landwater interface is well-defined. thus, appeaning addo et al. (2011) highlighted the prominence of remote sensing data as the preferred choice for monitoring shorelines. additional benefits of using the remote sensing approach include large ground coverage, relatively less timeconsuming, and less expensive coupled with the ability to repeat data acquisition, and monitoring (van and bihn, 2008). distinguished studies carried out on shorelines, coastal erosion, and identifying hotspots in ghana show that areas on the eastern coast, particularly the keta shoreline is highly dynamic, with an average rate of erosion estimated to be about 2±0.44 m/y (appeaning addo et al., 2011). individual rates along some transect reach as high as 16 m/year, for example near the estuary and on the east of the keta sea defence. in the coastal zones of greater accra, the rise in sea level is influencing shoreline change (appeaning addo, 2009; appeaning addo and adeyemi, 2013). furthermore, studies by dadson, et al. (2016) have shown that accretion and erosion are both active and have contributed to the fluctuations of the shorelines along the western coast of ghana disproportionately. in essence, most studies conducted on shoreline change either analyze it on a spatio-temporal basis with a focus on particular hotspots (appeaning addo et al., 2011; appeaning addo and adeyemi, 2013), or combine primary and secondary data to determine the rate of change at specified study sites (dadson et al., 2016; evadzi et al., 2017). specifically, studies on shoreline changes on the eastern coast have mostly focused on keta due to the presence of the sea defence wall (appeaning addo et al., 2011; jayson-quashigah et al., 2021), which presents a narrow scope of the challenges experienced on the eastern coast. the continuous changes observed in shorelines present socio-economic problems to coastal communities. in essence, to reduce the loss of coastal livelihoods, it is crucial to understand shoreline dynamics driven by complex and uneven magnitudes of events (chu et al., 2006, appeaning addo et al., 2011). analyzing shoreline changes is essential in environmental monitoring and coastal zone management (van and bihn, 2008). hence a historic assessment of the changing shorelines of the eastern coast will present a cumulative outcome of events and processes (natural and anthropogenic) that have altered the shoreline from 1991 to 2020 with the focus of informing coastal management practices. thus, our aims are to (1) examine the erosion trends; (2) assess the drivers of shoreline changes; and (3) identify exposed communities along the eastern coast of ghana. this will provide a basis to channel government resources in targeting coastal communities that are most vulnerable towards achieving sdg 13 (climate action), sdg 10 (reduced inequalities), and sdg 11 (sustainable cities and communities) towards the future that we want (sustainable development). materials and methods study area the study is focused on the eastern coast of ghana. ghana’s coastal zone is divided into three sections (fig. 1a): western, central, and eastern based on their geomorphological characteristics (ly, 1980; appeaning addo et al., 2011). our study was conducted on the eastern coast, which is 149 km long and stretches from aflao in the east to the laloi lagoon west of prampram (fig. 1b). the eastern coast is a sandy shoreline, and it is characterized by the eroding delta of the volta river. the delta was formed in the quaternary and was built of clay, loose sand, and gravel (ly, 1980; boateng 2012). in addition, the eastern coast is characterized by high-energy waves; their heights exceed 1 m in the surf zone. along the coast, the tidal range is between 0.68 m and 1.32 m (wellens-mensah et al., 2002, boateng 2012). this is because the study area is influenced by the southwest monsoon winds which blow at an orientation of 45°. the study area is characterized by an erodible sandy shoreline with barrier beaches and lagoon-constricting bars. the area's backshore is low-lying, including marshlands, coastal plains, and water bodies (kusimi and dika, 2012). the area is also characterized by sand and barrier beaches and sand bars along the shore with spatially and temporally varying widths (boateng, 2012). on the backshore of the eastern coast, there are two main water bodies, the volta delta, and the keta lagoon. the keta lagoon is ghana's largest lagoon, with a huge wetland that stretches to the volta delta (fig. 1b). under the ghana wetlands management project, the wetland has been declared a ramsar site, but it is one of the most vulnerable sites in ghana. the lagoon fresh water is separated from the gulf of guinea sea water by a strip of land spanning from the east of the volta estuary to the mouth of the keta lagoon. this swath of land was formed by the deposit of river sediment from the volta river (ly, 1980). the prevailing unconsolidated geology along the study area's coastlines provides a significant source of sediment to the shoreline (boateng, 2009). puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. 13 data type and source landsat data series (4 tm, 7 emt+, and 8 oli) from 1991 to 2020 was used to track and discern the shoreline changes of the eastern coast. the images (taken in 1991, 2001, 2011, and 2020) were acquired from the usgs website (table 1). landsat images have proven to be useful for studies relevant to coastal zone management according to several authors (pardo-pascual et al., 2012; liu et al., 2017; wicaksono et al., 2019), therefore we also applied them. data pre-processing, shoreline extraction, and analysis the envi 5.3 and arcgis desktop 10.7 software were used in this investigation. using the bilinear resampling method, the panchromatic band of the landsat images was used to pan-sharpen the images to a 15 m resolution. this aided in sharpening the image and defining the water-land divide. all the images were registered using the 1991 image as the base image to geometrically align each image (image-to-image rectification) in the same coordinate system (projected coordinate system: utm zone 30n) so that the matching pixels represented the same item. the separation of water and land was then accomplished through the supervised classification of two classes. the final product was exported to arcgis desktop as a shapefile. the data was cleaned using arcgis editing tools. arcgis add-on tool the digital shoreline analysis system (dsas) version 5.1 was mainly used for data processing (appeaning addo et al., 2011; dadson et al., 2016; zonkoun et al., 2022). this is a tool for calculating the rate of change of the shoreline from various shoreline positions over time. it provides a solid set of regression rates in a consistent and easily reproducible way that can be used to analyze vast amounts of data at various scales (bheeroo et al., 2016; nassar et al., 2019) attribute data was added to the shoreline data extracted according to the demands of dsas. the flat line-end type was used to buffer the merged shoreline data at 150 meters. using arcgis editing tools, the onshore part of this buffer was digitized. using the seaward intersection option, the default parameters of the dsas add-on were set using the coastline and baseline data in a personal database. transects were created with a maximum search distance of 1500 m from the baseline and a transect spacing of 200 m. a total of 772 transects were created at 200 m intervals throughout the entire stretch of shoreline from east to west. from the baseline, the transects were cast at simple right angles. the transect generated was used to calculate change statistics. the shoreline change rates were calculated using the linear regression rate (lrr) statistical approach during the full study period (1991-2020). the lrr was preferred because it minimizes potential random error and short-term unpredictability. the lrr was chosen as the most statistically robust strategy. scholars have used various methods to study shoreline change analyses. these methods include unmanned aerial vehicles (drones) to assess lateral shoreline change analysis (jayson-quashigah et al., 2019; angnuureng et al., 2022). others also rely on aerial photographs (solomon, 2005; ford, 2013;), or on field surveys (crowell et al., 1991). but fig. 1 the study area is in the demarcated coastal region of ghana (a). the study was performed on the eastern coast where several settlements and lagoons are located (b). table 1 characteristics of the applied landsat images. year sensor date path and row spatial resolution (m) radiometric resolution (bits) 1991 landsat 4 tm 03/01/1991 10/01/1991 192/056 193/056 30*30 8 2001 landsat 7 etm + 14/11/2001 21/11/2001 192/056 193/056 30*30 8 2011 landsat 7 etm+ 10/01/2011 01/01/2011 192/056 193/056 30*30 8 2020 landsat 8 oli 01/01/2020 13/01/2020 192/056 193/056 30*30 12 14 puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. in recent times, most scholars apply satellite imagery, because it is less expensive yet effective, particularly for historic studies as compared to other methods. some studies have used a combination of multiple approaches (appeaning addo et al., 2011; zagòrski et al., 2020), while others have used a single method in isolation. limitations the study relied solely on satellite image analysis for assessing shoreline change over the study area. the greatest limitations of the landsat imagery to evaluate sub-pixelrate erosion and accretion over time hinges on geometric and radiometric distortions associated with satellite movement and topography. however, these distortions were corrected using ground control points from the survey and mapping division of the lands commission of ghana, the official government institution responsible for land mapping and survey. the study results were validated using google earth and point vector data of towns in ghana, which confirmed the accuracy of the results. results shoreline positions of ghana’s eastern coast for shoreline analysis, a total of four shorelines were retrieved from satellite images. the findings demonstrate that major changes in erosion and accretion have occurred throughout the eastern coast (fig. 2) over a 29-year period. fig. 2 shoreline changes of the eastern coast (a) and a zoomed section (b) with coastal towns. puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. 15 the results of the analysis show that between 1991 and 2020 the shorelines have experienced both erosion and accretion (fig. 3). based on the 772 transects, the average rate of shoreline change was 8.0±2.6m/y, thus in general erosion was the dominant process. out of the 772 transects, 670 (86.79%) were erosional with 38.47% statistically significant. the highest rate of erosion was 24.5 m/y recorded at transect 405 and the lowest rate was 0.4 m/y. the mean rate of erosion at the eastern coast from 1991 to 2020 was 9 m/y. the number of accretional transects was 102 which represented 13.21% with 0% statistically significant accretion. the highest accretion rate was 3 m/y recorded at transect 674, and the lowest accumulation rate was 0.02 m/y. the mean rate of accretion was 1.5 m/y. temporal analysis showed that the period between 1991 to 2001 revealed that erosion ranged from 0.01 m to 16 m while accretion from 0.02 m to 2.9 m (table 2). overall, the average erosion difference between 1991 to 2001 was 4 m/y while the average accretion was 0.3 m/y. secondly, the period from 2001 to 2011 also showed that erosion ranged from 0.8 m to 18 m while accretion from 0.4 m to 2.9 m. the average erosion for the period 2001 to 2011 was 3 m/y while accretion was 0.2 m/y. again, the period from 2011 to 2020 showed erosion rates from 0.7 m to 24 m accretion ranging from 0.4 m to 3 m with an average erosion rate of 2 m/y and an average accretion rate of 0.4 m/y. finally, the period from 1991 to 2020 showed that erosion rates ranged from 0.01 m to 24 m while accretion rates ranged from 0.02m to 3m with an average erosion rate of 9 m/y and an average accretion rate of 1.5 m/y table 2 temporal changes of the dynamism of the entire studied shoreline between selected years. period erosion (m/y) accretion (m/y) 1991-2001 4 0.3 2001-2011 3 0.2 2011-2020 2 0.4 total: 1991-2020 9 1.5 the total change in the location of coastline between 1991 and 2020 is presented by the linear regression rate (lrr). figure 5 shows lrr of the transects for the four different years (1991, 2001, 2011 and 2020) using dsas. the areas west of keta generally experience erosion while areas east of keta towards aflao experience reduced rates of erosion and accretion. in summary, within the 149 km long eastern coast, shoreline changes over the years have been observed ranging from very high erosion (24 m/y) to very low erosion (0.4 m/y). in addition, accretion rates observed also ranged from maximum accretion (3 m/y) to very low accretion (0.02 m/y). the changing location of the coastline was merged with community locations as point data to give spatial reference and identification. the study identified 25 communities that fell in between the changing shorelines. these communities continue to suffer coastal erosion and tidal waves for 29 years (period of study). fig. 3 final results of the digital shoreline analysis system (a), and a zoomed section of the eastern coast showing the final results of the digital shoreline analysis system (b). 16 puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. discussion erosion trends of the eastern coast the findings from the shoreline change analysis showed that the eastern coast has been experiencing erosion and accretion over the past three decades. erosion along the coast has been rapid with increasing anthropogenic activities which continues to expose coastal communities to coastal hazards. erosion trends along the eastern coast are traced to the construction of the akosombo dam in 1962 which reduced alluvial deposits and increased erosion rates to 8 m/y as compared to 4 m/y before the construction of the dam (ly, 1980; appeaning addo et al., 2011). the results of this study revealed an ongoing erosion process with pockets of accretion which has been intensified along the entire coast for the period of the study with an average erosion rate of 9m/y and a maximum rate of 24 m/y around the estuary. pockets of accretion with an average rate of 1.5m and a maximum rate of 3 m/y were also recorded at the eastern portions of the eastern coastline as shown in figure 2. the temporal changes (i.e 1991–2001) have revealed that coastal erosion has increased within the study period at different rates. the period between 1991 to 2001 recorded an fig. 4 temporal changes in erosion and accumulation of the coastline between the selected years fig. 5 the linear regression rate (lrr) of the transects represents the total change in the location of the coastline between 1991 and 2020. puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. 17 average erosion of 4m/y and an average accretion of 0.3 m/y which was higher than the average erosion rate of 3 m/y and an average accretion rate of 0.2 m/y for the period 2001-2011. in addition, the period between 2011 and 2020 recorded the lowest average erosion of 2 m/y and an average accretion rate of 0.4 m/y. finally, the period between 1991 to 2020 revealed an incremental erosion average of 9 m/y and an average accretion rate of 1.5 m/y. the wide distribution of erosion shows that the western portion of the coastline saw an increase in erosion rates from 13 m/y (1991-2001) to 16 m/y (20012011) and maintained the 16 m/y from 2011 to 2020. the middle portion of the coastline around the estuarine region also witnessed an increase in erosion rates from 16 m/y in 1991 to 2001 to 18 m/y from 2001 to 2011 and further increased from 18 m/y to 24 m/y from 2011 to 2020 (figure 4). the estuarine region, given its physical characteristics of flat and unimpeded shoreline, constantly generates wave action that transports sediments eastward (codjoe et al., 2020). in addition, the construction of sea defense projects such as the keta sea defense, protected the coastal towns in keta since the defense (barrier) breaks down the waves. however, this cause offsets to neighboring coastal towns that do not have barriers particularly west of keta towards the estuary. the resultant effect of these erosion trends coupled with sea level rise and tidal waves cause flooding which destroys homes, schools, businesses, and livelihoods, mostly during the rainy season (boateng, 2012). also, the intensity of erosion rates has resulted in the retreating of the cape (boateng, 2009). before the construction of the keta sea defense in 2001, studies carried out by appeaning addo et al. (2011, 2018) and boateng (2009; 2012) show that maximum coastal erosion rates could reach as high as 15 m/y, however, after the construction of the defense, this has reduced whiles coastal erosion rates have increased west of the keta sea defence. this is consistent with the findings of this study, which shows the gradual increase of 16 m/y (highest rate) from 1991 to 2001 to 24 m/y (highest rate) from 2011 to 2020 around the estuarine region. accretion rates on the other hand are shown at the eastern portion with incremental rates between 0.3 m/y and 0.4 m/y coupled with low erosion rates of less than 5 m. this is because given the reduced sediment deposit since the construction of the akosombo dam, has influenced the gradual accumulation of sediments eastwards. furthermore, the variations in erosion rates are the result of different sea defense projects. despite its maladaptation effects, the various types of sea defense structures built along the coast increase erosion rates, as the case of the dzita-atorkor sea defense project, which only has revetments, and the ada sea defense project (figure 1), which only has groynes, as compared to the keta sea defence project, which has groynes, revetments, and nourishment (jayson-quashigah, 2021). the resultant effect is increased erosion rates and tidal events in the town of fuveme since it is found at the receiving end for excesses from the atorkor and ada sea defense projects as compared to the keta sea defense project which enjoys relative stability (jaysonquashigah, 2021). in spite of these interventions, coastal communities are still exposed to coastal hazards partly attributable to sea level rise, sandy beaches, and the lack of rocky headlands to intercept longshore drift from the western coast coupled with the destruction of wetlands and mangroves (kusimi and dika, 2012). drivers of shoreline changes a cursory review of existing literature on coastal erosion and accretion occurring on the eastern coast of ghana elucidates a number of natural causes including edaphic factors; and anthropogenic factors which are operating at different spatial and temporal scales but have colluded to shape the shoreline of the study area. the natural factors that influence the changes in the position of shorelines on the eastern coast include the orientation of the shoreline, waves, and tides, and the variations in sea level (ekow 2015; appeaning addo, 2015). the eastern coast before the construction of the akosombo dam in 1962 used to erode at 4 m/y, even though the coast received about 71 million m3/y of sandy deposit, and it was reduced to 7 million m3/y (boateng, 2012). however, other studies gave a range of 1 million m3/y to 2.5 million m3/y as a deposit received before the construction (tilmans, 1993 as cited in jaysonquashigah et al., 2021; anthony and blivi, 1999). despite the differences in the amount of deposits received, all researchers agree that since the construction of the dam, the eastern coast received only 10-50% of the previous sediment load. the orientation of the shoreline of the eastern coast as compared to the western coast of ghana, which has rocky headlands that are able to break the waves (dadson et al., 2016), is also an important contributing factor. the eastern coast has sandy beaches with no rocky headlands, and in addition, it is also affected by waves from the south-southwest direction, and a period of 6-16 seconds has been calculated to reach roughly 3 m (roest, 2018). with rates ranging from 0.3 to 1.5 million m3/year, waves approaching the coast are also responsible for some of the highest rates of unidirectional longshore sand drift (almar et al., 2015). the southwest monsoon is one of the main winds along the eastern coast. it blows in a south-west direction (210°–240°) from the sea to the land, at a 45° angle to the shore, and in the same direction as the waves (angnuureng et al., 2013). winds occasionally blow from the northwest during the harmattan season (december–february). wind speed vary between 1.7 and 2.6 m/s on a monthly basis (angnuureng et al., 2013). furthermore, climate change coupled with sea level rise at a present rate of 3.3mm will result in a rise of 5.8 cm in 2020 with projections of 16.5 cm by 2025 and 34.5 cm by 2050 (mesti, 2015). also, a 1.0 m anticipated sea level rise by 2100 might result in the loss of over 1000 km2 of land, affecting 132,000 people. flooding and coastline erosion are particularly dangerous on the eastern coast (mesti, 2015). 18 puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. the variation in sea level altering shorelines is a global phenomenon. in the case of ghana, several areas near accra are expected to be swamped between 2035 and 2065 (appeaning addo, 2014). ipcc reports further reiterate that climate change poses a lot of danger to coastal communities since sea levels are rising at an accelerating rate and will increase the alterations of shorelines (ipcc, 2022). anthropogenic activities contribute to accelerating the alteration of shorelines on the eastern coast of ghana. anthropogenic factors such as coastal engineering to reduce erosion rates further causes maladaptation and erosion continue to persist (jayson-quashigah et al., 2021). the temporal changes observed between the periods of 1991-2001, 2001 to 2011, 2011 to 2020, and 1991 to 2020 (figure 4) show that in the period 1991-2001(before the construction) of the keta sea defense, coastal erosion was caused predominantly by reduced sediments to the coastline due to the construction of the akosombo dam. subsequently, between the period of 2001 to 2011 after the keta sea defence was constructed, this changed the variations in coastal erosion, particularly to the west of the keta sea defense (figure 1) which saw an increase in maximum erosion rates from 16 m/y (1991-2001) to 24 m/y (2011-2020). despite these rates, the period between 2011 to 2020 shows a decline in average rates to 2 m/y which can be attributed to the subsequent construction of other sea defense projects at dzita-atorkor and ada even though the estuarine region still recorded a maximum rate of 24 m/y (figure 3). other anthropogenic activities focus on environmental degradation such as the destruction of ecosystems, particularly wetlands, and mangroves. anthropogenic factors, however, have accelerated the variation of shorelines particularly on the eastern coast of ghana. in the study area, there are reports of heavy sand-wining activities (appeaning addo et al., 2011) and the exploitation of mangroves in anyanui (boatemaa et al., 2013). recently, there are also reports of large-scale construction activities including the development of resorts along the coast. these findings are in line with studies that highlight the allure of the coast and how it fig. 6 temporal changes in erosion and accumulation of the coastline between the selected years puplampu et al. 2023 / journal of environmental geography 16 (1–4), 11–21. 19 leads to the alteration of coastal landscapes to serve agricultural, industrial, and residential land uses (wu et al., 2018). over the last century, the direct consequences of human actions have had a higher impact on the coastal zone than the impacts directly tied to observed climate change (menstachi et al., 2018; melet et al., 2020). direct repercussions include the drainage of coastal wetlands, deforestation, and the flow of sewage, fertilizers, and toxins into coastal waters. extractive operations include sand mining and hydrocarbon production, as well as the harvesting of fisheries and other living resources. the introduction of exotic species, and the construction of seawalls and other structures. damming, channelization, and diverting coastal streams harden the coast, change circulation patterns, and influence freshwater, sediment, and nutrient delivery. soft engineering solutions such as beach nourishment and foredune development have a direct or indirect impact on natural systems (nordstrom, 2004). sand mining, urbanization, commercial activity, fishing, oil and gold mining, and other human activities have all had an impact on ghana's shorelines (jaysonquashigah et al., 2021). conclusions this study analyzed shoreline changes on the eastern coast of ghana, which stretches from laloi lagoon west of prampram to aflao (149 km), and identified vulnerable coastal communities using satellite images from the landsat satellite mission (landsat 4tm, 7etm+ 8 oli) from 1991 to 2020. findings revealed that the eastern coast has witnessed significant changes (maximum erosion: 24 m/y; maximum accretion: 3 m/y) over the studied period. the analysis further showed that some coastal communities have experienced massive erosion, thus they are highly exposed to coastal hazards. in addition, natural and anthropogenic factors continue to pose a number of threats to coastal communities. indeed, hard adaptation interventions such as sea defense walls have been already constructed, and further plans exist to construct new sea defense walls. the sea defense wall at the estuary/ delta area (at keta) has reduced the rates of erosion, even though the area has suffered from short-term events such as tidal waves in recent times which have led to the displacement of thousands of households. the climate change-driven sea level rise is coupled with population growth in coastal communities, and the erosion of the coastlines will not slow down along the coasts of ghana. the increase in population and urbanization coupled with the exploitation of coastal resources such as sand and mangroves, continue to expose coastal communities. since climate change and population trends, all show incremental growth, it is imperative to ensure that the coastal environment is safe, inclusive, and sustainable. the coastal region creates employment and supports livelihoods and is pivotal to the development of ghana. thus, the following actions are recommended: (a) the promotion of ecosystem-based adaptation using a community participatory approach is needed to ensure the cultivation and protection of mangroves, which has a triple-win benefit for nursing fisheries, serving as a breakwater for excess runoffs and the sequestration of carbon which will protect properties and livelihoods. (b) frequent coastal monitoring is needed to ensure an up-to-date report on erosion trends in an era of sea level rise and create scenarios to predict threats that will inform policy decision-making processes such as the relocation of highly exposed coastal dwellers. (c) the implementation of integrated coastal management practices is necessary to ensure that anthropogenic activities such as the destruction of wetlands, sand wining, and destruction of mangroves are reduced to the barest minimum with community participation to build coastal resilience towards the future that we wantsustainable development. acknowledgments we are grateful to the remote sensing and geographic information systems laboratory (rs/gis), the department of geography and resource development at the university of ghana, and the united states geological survey (usgs) for making new versions of dsas and satellite imagery available to carry out this study. declaration of interest statement the authors certify that they have no known competing financial interests that may have influenced the work presented in this paper. references almar, r., kestenare, e., reyns, j., jouanno, j., anthony, e.j., laibi, r., ranasinghe, r. 2015. response of the bight of benin (gulf of guinea, west 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and analysis limitations results shoreline positions of ghana’s eastern coast discussion erosion trends of the eastern coast drivers of shoreline changes conclusions acknowledgments declaration of interest statement references woody plants interaction with aerosol fine particulate matters and copper in budapest journal of environmental geography 16 (1–4), 31–37. doi: 10.14232/jengeo-2023-44584 issn 2060-467x woody plants interaction with aerosol fine particulate matters and copper in budapest haimei chen1,2, levente kardos1,*, veronika szabo2, magdolna diószegi2, peter honfi2 1hungarian university of agriculture and life sciences, department of floriculture and dendrology, institute of landscapes architecture, urban planning and garden art, villányi ut, 29-43, 1118, budapest, hungary 2hungarian university of agriculture and life sciences, department of agro-environment studies, institute of environmental science, villányi ut, 29-43, 1118, budapest, hungary *corresponding author: kardos.levente@uni-mate.hu research article, received 25 april 2023, accepted 7 july 2023 abstract ambient particulate matter pollution is the primary concern as it has a significant impact on human health and the majority of the world's population lives in urban areas. heavy metals are the most concerning component of particulate matter, and cu is a highly traffic-related emission element whose overabundance results in toxic effects. woody plants, on the other hand, contribute to the removal of airborne pollution in urban areas. our aims are (1) to compare urban woody plants abilities to capture ambient fine particulate matter on leaf surface; and (2) to access the cu concentration loads on their leaf surfaces. consequently, our results will provide scientific knowledge for future urban planning concerning air pollution remediation. we investigated the relationship between woody plants and heavy metal pollution in budapest. four woody plant species were sampled at different traffic densities. their cu contents in the leaf and branch were measured, our results show that tilia tomentosa and acer platanoides are better options for ambient cu accumulation than fraxinus excelsior and aesculus hisppocastanus in urban environments. at different traffic densities and sampling times, however, cu accumulation did not vary across species. this is because, through translocation, woody plants absorb cu not only from the air but also from the soil. furthermore, it is also because of the long-distance transportation and long-term suspension of fine particulate matter. from the obtained results, we can conclude that woody plants are important phytoremediation elements in the urban area of budapest. planting t. tomentosa and a. platanoides in urban areas of central europe will be promising for ambient heavy metal pollution phytoremediation. but environmental conditions differ from one place to another. therefore, a comprehensive study is required in order to apply the results to different locations. keywords: woody plants, copper, ambient pollution, phytoremediation introduction particulate matter pollution, pm10 (particulate matter 10 µm) and pm2.5 (2.5 µm), is the most prevalent pollutant in urban areas and has been a concern in recent decades because of its negative impact on the environment and public health (abhijith et al., 2017; li et al., 2022). compared to large particulate matter, fine particulate matter persists in the air for a longer duration and poses a more significant threat to the environment and human health (ferenczi and bozó, 2017). for health considerations, the world health organization (who) suggests a daily pm 2.5 interim target of 5µg/m3 and an annual pm 2.5 interim target of 35 µg/m3 (who, 2021). among all particulate matter components, heavy metals are the most concerning because of their toxic effects (faraji ghasemi et al., 2020). in urban areas, the primary sources of pm are household combustion and traffic-related emission, and road traffic emissions can contribute up to 19% of the pm2.5 concentrations in the urban area (ferenczi et al., 2021). in the study of perrone et al. (2018), the pm 2.5 concentration is 17 µg/m3 in budapest, which is much higher than the limit of who’s recommendation (5 µg/m3). thus, it is still a challenge to improve the air quality in hungary. urban green infrastructure, such as street trees, vegetation hedges, and parks, is an important way to remove atmospheric particulate matter and improve air quality (abhijith et al., 2017; hrotkó et al., 2021; jin et al., 2021). despite the fact that coniferous species have been shown to have a high potential in pm trapping, they are not recommended to use as roadside trees, because they are less tolerant of high traffic -related pollution and have a difficult time surviving in the stressed urban environment, particularly if salt is use d for road de-icing in the winter (dzierżanowski et al., 2011). thus, broadleaved trees are the better option in the aspect of tolerance the urban environment and provide pollution purifying effect in urban planning. the ability to successfully capture pm is a crucial factor in selecting the best plant species for urban greening; therefore, it is essential to examine the fine pm capture ability of various plant species in order to optimize their use in diverse urban environments. several studies have been carried out in different countries to estimate woody plants' potential for https://doi.org/10.14232/jengeo-2023-44584 mailto:kardos.levente@uni-mate.hu 32 chen et al. 2023 / journal of environmental geography 16 (1–4), 31–37. accumulating pm. for example, hofman et al. (2016), discovered woody plant trapped 626 mg/m2 of pm10 and 33.69 mg/m2 of fine pm (0.2-3 µm) on the leaf surface. jeanjean et al. (2016) reported 2.8% of atmospheric pm reduction from tree and grass leaf deposition. according to nowak et al. (2006), urban trees removed 711,000 tons of particulate pollution in us. several studies have conducted the accumulation of heavy metals on leaf dust deposit. ramesh and gopalsamy (2021) found saraca asoca captured 235.53 mg/kg of fe and 157.91 mg/kg of al on the leaf surface in kanchipuram, india. they suggest woody plants as good biomonitors for ambient heavy metal pollution. similarly, li et al. (2022) concluded woody plants' foliar dust could reflect the best of the ambient elemental composition by testing pb, zn, cd, cu, ni and mn in the foliar dust, plant leaves, surface soil, and subsoil from twenty-three plant species in qingdao, china. el-khatib et al. (2020) found non-essential elements, such as pb concentrated on leaf surface dust because of aerosol deposits and plants may actively exclude them to minimize their toxic impact and leaf is a better option as a biomonitor than bark in minya, egypt. kiss et al. (2017) demonstrated that heavy metal loads in tree rings can spatially and temporally reflect urban environmental conditions. however, the effect of woody plants on pm reduction and the adsorption mechanism is unknown, and direct monitoring of ambient heavy metal pollution is limited by the high cost and unreliable information on the impact of atmospheric pollutants on ecosystems (alahabadi et al., 2017). in this study, we aim to evaluate the ability of urban plant species to capture fine particulate matter on leaf and branch surfaces. in addition, we aimed to compare their cu deposition on the leaf surface. thus, our findings will contribute to the species selection in the future urban planning regarding sustainable development. materials and methods sampling sites budapest, the capital of hungary, is home to approximately two million people. it has a temperate climate influenced by both the oceanic and mediterranean climates. the annual average temperature is 12.6 °c, with an average of 2040 h/year sunshine. the average yearly precipitation is 530 mm, with the majority of rain falling from may to june and early autumn (mean of 20 years: 2001-2020) (www.met.hu). the study area, deák ferenc tér is located downtown, where there is heavy traffic (fig. 1). the buda arboretum is on the south slope of gellért-hill, which is an urban park with 7.5 ha in area and 1900 woody plant species (schmidt and sütöridiószegi, 2013) species and sampling sampling was conducted three times during the spring, summer, and autumn of 2021. leaves and branches from four different woody plant species (acer platanoides, aesculus hippocastanum, fraxinus excelsior, and tilia tomentosa) were collected from the above mentioned two locations. the habits of these species, their leaf shapes and surface characteristic, and the measured mean area are listed in table 1. five trees of each species were chosen, 20 leaves and 3 second-year-old branches with a 10cm diameter were collected from each tree. after sampling, the fresh leaves and branches were dried to constant weight. then the leaves and branches were soaked in distill water for one hour, and then shaken in an ultrasonic machine for 10 minutes. the dust suspensions were filtered by filter paper (pore size 2.5-4 m) and evaporated until constant dryness. the weight of pm was measured with an electronic scale (adventurer, ohaus, parsippany-troy hills, nj, usa). the residues were then digested by a wet digestion method, applying concentrated (30%) hydrogen peroxide (h2o2) and fig.1 sampling sites (sources: gadm and google maps) chen et al. 2023 / journal of environmental geography 16 (1–4), 31–37. 33 concentrated (65%) nitric acid (hno3), and then diluting with distillate water to 100 ml. an am350 leaf area meter was used to measure leaf area (adc bio scientific ltd., uk). the real-time images and measured parameters were exported to excel files, and then the average leaf area was computed into square meters (m2). the cu contents were determined by an atomic absorption spectrometer (aas) aurora ai 1200 (aurora instruments ltd., canada). data analysis the dust retention amount and mass of element per unit leaf area and per unit branch dry weight (dw) were calculated as follows (li et al., 2022): 𝐷𝑢𝑠𝑡 𝑟𝑒𝑡𝑒𝑛𝑡𝑖𝑜𝑛 𝑎𝑚𝑜𝑢𝑛𝑡 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑢𝑠𝑡 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑒𝑑 𝑓𝑟𝑜𝑚 𝑒𝑎𝑐ℎ 𝑙𝑒𝑎𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 𝑃𝑟𝑜𝑗𝑒𝑐𝑡𝑒𝑑 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑝𝑙𝑎𝑛𝑡 𝑙𝑒𝑎𝑣𝑒𝑠 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 𝑝𝑒𝑟 𝑢𝑛𝑖𝑡 𝑙𝑒𝑎𝑓 𝑎𝑟𝑒𝑎 / 𝑑𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡 = 𝐸𝑙𝑒𝑚𝑒𝑛𝑡 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑓𝑜𝑙𝑖𝑎𝑟 𝑑𝑢𝑠𝑡 × 𝐷𝑢𝑠𝑡 𝑟𝑒𝑡𝑒𝑛𝑡𝑖𝑜𝑛 𝑎𝑚𝑜𝑢𝑛𝑡 the dust retention amount per unit leaf area was calculated into µg/cm2 and per unit dw in µg/g. we used the spss 27.0 software package (spss inc., chicago, il, usa) and microsoft excel 2017 to analyze the data set. in spss, the normal distribution was verified with the shapiro-wilk test (ibm corp.). an independentsample t test was used to compare the differences between two locations. a one-way anova model with a gamehowell posthoc test (p < 0.05) was carried out to test the differences between species and sampling times. the relationship between pm content and the mass of cu was calculated by the pearson correlation coefficient (twotailed) and the curves were estimated by regression. results amount of pm loaded on leaf surfaces and branches our results revealed that different woody plant species' capacities for pm capture are significant from one to the other (table 2). pm2.5 is the most harmful to human health as it travels a longer distance and suspends in the atmosphere for longer period of time (ferenczi and bozó, 2017; jin et al., 2021). the pm loaded on the leaf surface and branches ranged from 5 to152 µg/cm2 and 66.22 to 6587 µg/g respectively, with the highest average value of 57.05 µg/cm2 at the leaf of t. tomentosa and the lowest at a. hippocastanum and the highest average on the branch of a. hippocastanum and lowest on f. excelsior. similarly, jin et al. (2021) measured 27.76 to 74.89 µg/cm2 of pm from different woody plant species. our result also showed similar values as the study of hrotkó et al. (2021), that t. tomentosa captured a higher amount of dust on the leaf surface than a. platanoides, followed with f. excelsior. the order of fine pm capture in our study was t. tomentosa, a. platanoides, f. excelsior, a. hippocastanum. this is because the characteristic features of the leaf surface highly impact the pm accumulation (aničić et al., 2011; norouzi et al., 2015; nadgórska– socha et al., 2017; choi et al., 2021). the abaxial surface of the leaf appears to retain a higher number of fine pm than the adaxial surface, because such a leaf components, like trichomes and granulated epicuticular wax layer increase the pm accumulation (chen et al., 2017; gajbhiye et al., 2019). considering presence of tomentosa at the abaxial surface of t. tomentosa, this may result in a higher concentration of fine pm than in other species. pm accumulation on branches also shown noble difference between species, as a. hippocastanum had the highest values, followed by a. platanoides and t. tomentosa, and the lowest values were measured for f. excelsior. it is because the differences between branch surface. the pm contents of foliar dust and branch dust were not significantly different between locations of the same species (fig. 2). this is in contrast to other studies, as sevik et al. (2019) and aricak et al. (2020) stated that traffic density significantly influences pm deposition on table 1 main characteristics of the species and their leaves studied in this research species family leaf shape leaf surface average leaf area (cm2) acer platanoides sapindaceae palmately lobed leaf glabrous 91.4 aesculus hippocastanum sapindaceae compound leaf glabrous when mature 361.1 fraxinus excelsior oleaceae heart-shaped leaf smooth 124.8 tilia tomentosa malvaceae compound leaf with tomentosa 50.9 table 2 leaf and branch fine pm accumulation organ species a. platanoides a. hippocastanum f. excelsior t. tomentosa leaf pm (µg/cm2) 42.0 b 29.9 c 46.4 b 57.1 a branch pm (µg/g) 1265.5 ab 1813.2 a 694.3 b 1375.9 ab 34 chen et al. 2023 / journal of environmental geography 16 (1–4), 31–37. leaf surfaces. because fine pm has a lifetime ranging from days to weeks and may travel large distances, including across borders (ferenczi et al., 2021). furthermore, fine pm captured on the leaf surface is harder to wash off by rainfall or blow off by wind, as the fine pm accumulates inside stomata rather than depositing over the epidermal and stomata surfaces (gajbhiye et al., 2019). thus, within a metropolis, the difference between two places with varying traffic densities may not produce statistically significant findings. our results agreed with those of jin et al. (2021), i.e., that species are significantly different in pm capturing. the growth parameters of plants also influence the deposition of pm on the foliar and branch surfaces (mori et al., 2015). although the biomass of the branch is not as big as that of the leaves, which can be considered in phytoremediation or phytoextraction, it is also recommended to monitor the atmospheric deposition because it reflects the exposure period of time and forms annual segments that can be easily distinguished (drava et al., 2017). mass of copper on foliar and branch dust the mass of cu on leaf and branch surfaces is shown in table 3. the cu content of foliar dust ranged from 0.64 to 51.18 µg/g, and no significant differences were found between leaf surfaces of the species. while the branch dust ranged from 33.9 to 280.44 µg/g with significant differences, it was the highest at t. tomentosa, followed by a. platanoides and a. hippocastanum, and the lowest at f. excelsior. cu is a necessary element for plant growth. in the ambient, the main source of cu is from the high rate of brake abrasion because of increased stopping and low speeds of vehicles (świetlik et al., 2013). the result of branch dust in this study, whose average ranges from 61.2 to 145.38 µg/g, is similar to the study of świetlik et al. (2013), as the cu concentration in the road dust from poland was 152 µg/g. while the cu content in the foliar dust was much lower, this might indicate that cu loaded on the leaf surface can be translocated into the leaf and used for plant growth. the comparison of cu content between two locations showed no significant difference between the species in both foliar and branch dust (table 4). this corresponds to the result of pm content. thus, we can conclude that fine pm and cu contents did not show a significant difference between an urban park and a heavy traffic area. we further compared the differences between different seasons. the statistical results indicated differences between seasons for all species (as table 5). the foliar dust of a. platanoides and t. tomentosa showed the same trend, being the highest in spring and lowest in summer, while a. hippocastanum showed the opposite trend, and f. excelsior did not have significant differences in all seasons. human activities release large quantities of heavy metals into the atmosphere; these heavy metals are easily adsorbed onto particulate matter in the atmosphere and then retained on plant leaves, resulting in extremely high concentrations of heavy metals in foliar dust (li et al., 2022). our results show the content of cu in foliar dust was below the toxic level and the hungarian soil background value [6/2009. (iv.14.) kvvmeüm-fvm] as well; however, the content on the branch exceeded the background value and pollution limit value (csorba et al., 2014). fig.2 pm concentration on the leaf surface (µg/cm2) and branch surface (µg/g) table 3 copper concentration of foliar and branch dust (µg/g) species a. platanoides a. hippocastanum f. excelsior t. tomentosa leaf 14.9±13.1 a 13.14±8.2 a 15.3±9.9 a 13.1±9.5 a branch 102.4±31.5 b 89.9±33.6 bc 61.2±21.2 c 145.3±57.1 a note: letters indicate significant differences between species (p<0.05). chen et al. 2023 / journal of environmental geography 16 (1–4), 31–37. 35 relationships between the pm and cu mass on leaf surface considering there were significant differences between pm capture on the foliar dust, but no difference between the cu contents, we further analyzed the relationships between the pm content and cu mass in the foliar dust. the cu content of foliar dust from all species tested had a significant correlation with the mass fine pm deposition (r2 >0.5), with the strongest correlation in f. excelsior (r2 =0.794) (fig. 3). this corresponded to the study of mori et al. (2015), the pm on the leaf surface and the element load share similar characteristics. thus, the deposition of elements is highly related to the pm accumulation on the leaf surface; however, the plants uptake elements not only from the soil but also translocate them from the leaf surface (serbula et al., 2013; el-khatib et al., 2020). discussion more than half of the world's population resides in urban areas, making the urban green future crucial (abhijith et al., 2017). urban green infrastructures are contributing several benefits. proper plant species should be able to tolerate the extreme urban environment, such as shade, drought, poor soil, continuous pruning, and air pollution (szaller et al., 2014). despite that, suitable species will provide ornamental value, generate environmental benefits, and provide health benefits (ulmer et al., 2016; turan et al., 2020). the ability of woody plants to accumulate pm in urban areas is determined by various aspects, including the physical and chemical properties of pm, hazardous element forms, leaf shape, the biological status of plants, leaf surface, the exposure period, and ambient conditions. urban design requires a comprehensive examination of the ambient conditions as well as the capacity of woody plants to tolerate the urban environment and provide pm filtration benefits. our preliminary results evaluated woody plants' potential for fine pm accumulation in urban areas of budapest. t. tomentosa showed higher ability in pm capturing than other species, and there was no significant difference between two locations in all species. in the case of cu deposits, there were no significant differences between species or the same species in different locations. which might be because cu can be incorporated into leaves. in the future, more work is needed to confirm the uptake of cu in the woody plants' leaves. estimating the total amount of pm deposits in a tree will provide useful information about the phytoremediation efficiency of air pollution. conclusion massive quantities of airborne particulate matter are produced by human activities, endangering the health of the majority of the world's population. on the other hand, urban ecological infrastructures are promising for pm procurement. leaf and branch dust are essential air pollution monitoring parameters due to their low cost and effectiveness. our study assessed the ability of prevalent woody plant species in budapest to capture pm in their leaves and branches. we also investigated the cu contents, this study's findings for all species did not reveal elevated cu pollution levels in budapest. furthermore, we analyzed the relationship between cu and the pm deposit. our findings also demonstrate that leaves are effective at absorbing ambient elements. in budapest, t. tomentosa is considered more effective at fine pm capture than a. table 4 difference of copper contents of foliar and branch dust by locations (µg/g) species location a. platanoides a. hippocastanum f. excelsior t. tomentosa leaf aboretum 15.2±6.6 15.1±9.7 17.3±12.9 12.9±9.4 deák ferenc tér 14.6±9.2 11.2±6.4 13.3 ±5.5 13.3±10.0 aboretum 116.7±35.6 88.2±34.9 52.5±12.1 172.6±67.8 branch deák ferenc tér 88.1±19.3 91.6±33.7 69.8±25.2 118.1±24.3 note: letters indicate significant differences between species (p<0.05). table 5 difference of copper contents of leaf and branch dust by sampling time (µg/g) species samplingtime a. platanoides a. hippocastanum f. excelsior t. tomentosa leaf spring 19.9±7.2 a 8.4±6.3 b 12.6±6.6 a 19.6±8.8 a summer 7.6±2.0 b 18.4±5.5 a 19.3±6.6 a 5.2±4.0 b autumn 14.8±7.9 ab 12.5±3.8 ab 14.0±5.7 a 14.5±6.1 ab branch spring 123.8±36.8 a 104.7±30.6 a 62.9±18.9 ab 178.0±80.7 a summer 87.6±23.5 b 59.3±13.5 b 44.0±11.1 b 140.5±28.5 a autumn 95.7±23.2 ab 105.7±31.3 a 76.6±19.7 a 117.5±36.0 a note: letters indicate significant differences between sampling time (p<0.05). 36 chen et al. 2023 / journal of environmental geography 16 (1–4), 31–37. 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(iv.14.) kvvmeüm-fvm együttes rendelet a földtani közeg és a felszín alatti víz szennyezéssel szembeni védelméhez szükséges határértékekről és a szennyezések méréséről: 2015.iv.1. https://doi.org/10.4209/aaqr.210048 https://doi.org/10.1016/j.ecolind.2019.04.072 https://doi.org/10.1016/j.ufug.2016.09.013 https://doi.org/10.1007/s10653-020-00769-y https://doi.org/10.1016/j.atmosenv.2016.09.033 https://doi.org/10.3390/f12040438 https://doi.org/10.2478/jengeo-2019-0002 https://doi.org/10.1016/j.chemosphere.2021.132341 https://doi.org/10.1016/j.ufug.2015.02.008 https://doi.org/10.1016/j.chemosphere.2017.05.128 https://doi.org/10.1016/j.ecolind.2015.04.011 https://doi.org/10.1016/j.ufug.2006.01.007 https://doi.org/10.1016/j.scitotenv.2017.11.092 https://doi.org/10.31018/jans.v13i3.2739 https://doi.org/10.4209/aaqr.2012.06.0153 https://doi.org/10.1007/s11869-019-00717-5 https://doi.org/10.1016/j.ufug.2020.126918 https://doi.org/10.15414/2014.9788055212623.28-31 https://dergipark.org.tr/tr/download/article-file/1242667 https://doi.org/10.1016/j.healthplace.2016.08.011 https://apps.who.int/iris/handle/10665/345329 https://www.met.hu/eghajlat/magyarorszag_eghajlata/%20eghajlati_adatsorok/budapest/adatok/eves_adatok/ https://www.met.hu/eghajlat/magyarorszag_eghajlata/%20eghajlati_adatsorok/budapest/adatok/eves_adatok/ introduction sampling sites species and sampling data analysis results amount of pm loaded on leaf surfaces and branches mass of copper on foliar and branch dust relationships between the pm and cu mass on leaf surface discussion conclusion acknowledgement references the importance of protein fingerprints in bacterial identification the maldi-tof technique journal of environmental geography 16 (1–4), 38–45. doi: 10.14232/jengeo-2023-44716 issn 2060-467x the importance of protein fingerprints in bacterial identification the maldi-tof technique ali haider1,*, marianna ringer2, zsolt kotroczó3, csilla mohácsi-farkas4, tamás kocsis4 1doctoral school of food sciences, hungarian university of agriculture and life sciences, villányi út, 29-43. h-1118 budapest, hungary. 2geographical institute, research centre for astronomy and earth sciences, h-1112 budapest, hungary. 3department of agro-environmental studies, hungarian university of agriculture and life sciences, villányi út, 29-43. h-1118 budapest, hungary. 4department of food microbiology, hygiene, and safety, hungarian university of agriculture and life sciences, villányi út, 29-43. h-1118 budapest, hungary. *corresponding author: ali-haider90@hotmail.com research article, received 21 may 2023, accepted 19 july 2023 abstract the available literary sources suggest the general applicability and benefits of the matrix-assisted laser desorption/ionization (maldi) time-of-flight (tof) mass spectrometry (ms) in the field of microbiological identification including food quality and safety, and the clinical field. due to its high reliability, maldi-tof might generally be the alternative to the sequence-based and serological-based methods. the essence of the technique is to map the unique protein pattern of microbes that contributes to characterizing a wide variety of microorganisms, including bacteria, fungi, and viruses. on the other hand, these applications only have reliable results under certain conditions (homogeneous infection, adequate cell count, appropriate separation technique). in this review, we focused on the application of maldi-tof ms for the environmental field where it has significant potential in the identification, differentiation, and categorization of environmental samples which includes (soil, water, and air), furthermore, some challenges, especially in case of the extreme conditions environment and summarize developments that have been enabled for routine application in the field of environment. keywords: microbial identification, environment, maldi-tof, protein pattern, mass spectrometry introduction the identification of microorganisms is essential in different fields. generally, this identification is made by morphological (e.g. cell shape), phenotypic (e. g. gram staining), and genetic tests (e.g. polymerase chain reaction pcr). the morphological and phenotypic tests are time-consuming, while the genetic tests require a high level of expertise and are quite expensive. therefore, these techniques are not ideally suitable for routine identification and alternatives would be welcome for the rapid and low-cost identification of microorganisms (rychert, 2019). new technologies for accurately and rapidly identifying bacteria are essential in various fields of applied microbiology. mass spectrometry is an alternative solution for identifying and typing. this analytic technique can analyze the mass-to-charge ratio of numerous biomolecules, such as peptides and proteins (simke et al., 2022). matrix-assisted laser desorption ionization (maldi) is currently used for this purpose. the essence of the maldi measurement is that the molecules of the examined sample are ionized with the contribution of an auxiliary material (matrix) that can absorb the excess laser energy used for ionization (beavis and chait, 1989). the analytes are embedded in the crystal of the matrix, which transfers the laser energy to the molecules of the analyte (batoy et al., 2008). during the process, the macromolecule-matrix complexes from the test sample are released (desorption phase), and then the resulting molecular ions are delivered to the analyzer under high vacuum and accelerating voltage (fig. 1). the first description of using maldi-tof mass spectrometry technology for bacterial biomarkers was published in 1975 (anhalt and fenselau, 1975). still, it took a long time to introduce this technology in routine microbiology. over and above in 2004, the first complete database for bacterial identification was reported (keys et al., 2004). at the same time, it was quickly recognized that this technique is also suitable for examining the unique protein pattern of microbes (jones et al., 2003). the maldi-tof ms is now a widely used technique to characterize a wide variety of microorganisms, including bacteria, fungi, and viruses (giebe et al., 2010). a multicenter evaluation study of the malditof ms system for identifying gram-negative bacteria was performed, including a total of 2,263 isolates representing 23 genera and 61 species. the study showed that the malditof ms system https://doi.org/10.14232/jengeo-2023-44716 mailto:ali-haider90@hotmail.com haider et al. 2023 / journal of environmental geography 16 (1–4), 38–45. 39 correctly identified 99.8% at the genus and 98.2% at the species level (faron et al., 2015). spanu et al. (2011) evaluated the application of maldi-tof ms for identifying the most relevant species of the staphylococcus genus, using the rpob gene sequencing method as a reference. correct species identification was achieved in 99% of strains until the subspecies level. handal et al. (2015) aimed to evaluate the reliability of identification by maldi-tof ms compared to 16s rrna sequencing of the most common clinically relevant anaerobic bacteria, including bacteroides spp., clostridium spp., prevotella spp., fusobacterium spp., and grampositive anaerobic cocci. authors reported that the maldi-tof ms correctly identified about 95% of the anaerobes to the genus level, and 87% to the species level, with identification errors mainly among the non fragile bacteroides spp. and the gram-positive anaerobic cocci. maldi-tof proved to be a successful method for identifying anaerobes. materials and methods approach to the methodological concept in recent years, maldi-tof ms can be found in routine laboratories and utilized as an alternative approach for identification. during the preparation process, the sample can practically be picked up with a sterile toothpick and prepared on a target plate, which should be covered with 1 µl formic acid. when dried, it is overlayed with 1 µl α -hcca (α-cyano-4hydroxycinnamic acid in 50% acetonitrile and 2.5% trifluoroacetic acid) matrix solution and left to dry again (bizzini and greub, 2010). after the crystallization of the matrix-analyte mixture on the target plate, it is targeted with short laser pulses, usually from a uv/vis laser. the matrix absorbs the laser energy, leading to the desorption of the analytes, which are then vaporized and ionized into the gas phase. this matrix-assisted desorption and ionization of analytes lead to the formation of predominantly singly charged sample ions. the desorbed and ionized molecules are first accelerated by an electrostatic field and then ejected through a flight tube subjected to a vacuum until they reach the detector. the time of flight (tof) required to reach the detector depends on the mass (m) and charge (z) of the analyte and is proportional to the square root of m/z (carlsohn et al., 2007). thus, bioanalytics with different m/z that make up a complex sample are separated according to their tof, creating a mass spectrum characterized by both m/z and ion intensity, corresponding to the number of ions. based on this mass spectra information, a characteristic fingerprint can be recorded of organic matter that can be investigated typically between 2000 and 20,000 m/z. in this range, the signal-to-noise ratio is very stable and easily detectable (wieser et al., 2012). generally, maldi produces singly charged (z = 1) ions, so the m/z value of the analyte corresponds to its mass plus cation adduct (croxatto et al., 2012). maldi-tof ms, that can measure peptides and other compounds to analyze their complex mixture, is an ideal method for measuring non-purified extracts and intact bacterial cells (biotyper). it looks like a rapid, accurate, and cost-effective way of microbial characterization and identification compared to fig.1 overview of the investigation process. the sample–matrix complex is evaporated and ionized by laser irradiation. the ions are accelerated in an electric field and drift in a field-free pathway under a vacuum. during the flying, a separation between low-mass and high-mass ions occurs. the flight time depends on the length of the flight path, the ion’s mass, its energy, and the value of charges. 40 haider et al. 2023 / journal of environmental geography 16 (1–4), 38–45. classical and molecular ways. during the measurement, mass spectral fingerprints generate from the sa mple’s protein content, unique signatures for each microorganism at the species level (fig. 2). results maldi-tof ms environmental microbiology applications maldi-tof ms has been extensively applied and is still mainly used in the clinical field as shown by the number of published reviews (van belkum et al., 2012) in the last years, hundreds of systems have been installed worldwide in clinical microbiology laboratories. the importance of rapidly identifying microorganisms involved in human infections and applying the right therapeutic is unquestionable. however, maldi-tof ms can also provide a significant contribution to environmental microbiology (santos et al., 2016). the identification of microorganisms from environmental sources is necessary to understand the microbial community, for environmental monitoring, and to identify possible pathogenic microorganisms. maldi-tof ms has been an important advance in the field of environmental proteomics as the protein fingerprint of each microorganism can be used for identification. the identification can be performed by comparing the unknown protein profile to a database of reference profiles or by co-analyzing the unknown profile with profiles of known bacteria (santos et al., 2016). previous findings have described the application of maldi-tof ms in the identification of microorganisms in environmental samples such as sewage sludge, marine sponges, water, soil, roots, and the rhizosphere (dieckmann et al., 2005; lovecka, et al., 2015) for example, in the work by emami et al. (2012) malditof ms was used to characterize bacteria in ballast water. thirty-six isolates were identified, at the genus level, and the results were similar to those obtained by 16s rrna gene sequencing. for higher-quality spectra, the authors used cell lysates from actively growing colonies instead of crude cells and α-cyano-4-hydroxycinnamic acid (hcca) as a matrix that they found to be an important factor when trying to differentiate between closely related isolates. in the same context, štursa et al. (2009) and ferreira et al. (2011) studied the application of maldi-tof ms for the identification and characterization of microorganisms in the rhizosphere of plants. in the former work, the authors built a database containing protein profiles of 56 species of fast-growing rhizobia and were able to identify large populations of isolates from nodules with 100% effectiveness. furthermore, they concluded that maldi-tof ms is a very useful tool for diversity and ecological studies. application of maldi-tof ms in monitoring the microorganisms at specific stresses maldi-tof ms can be used in the identification of proteins associated with specific stresses. when subjected to changes in environmental parameters, microorganisms change their protein expression profiles, as a response to overcome these changes. these differences in the protein expression profiles can be used as an indicator of environmental pollution. in the work by (heim et al., 2003) maldi-tof ms was used to identify proteins produced by pseudomonas putida due to iron limitation stress. the authors were able to identify 25 proteins that were up and downregulated due to iron deprivation. lacerda, et al. (2007) used maldi-tof ms, and de novo fig.2 workflow of sample preparation and profile analysis by maldi-tof biotyper. (a) sampling from the colony, (b) preparation on maldi target plate, (c) instrumental measurement, (d) generating mass spectra, (e) calculating maldi-tof profile spectra. during the measurement, the generally known peaks are identified, and their pattern is compared with the reference list in a database. haider et al. 2023 / journal of environmental geography 16 (1–4), 38–45. 41 sequencing to identify proteins differentially expressed over time following exposure of a bacterial community to an inhibitory level of cadmium. munoz et al. (2011) verified that maldi-tof ms analysis of whole cells is a powerful tool for studying the cultivable fraction of hypersaline environments. the authors used malditof ms to classify bacterial isolates into 25 phenotypic clusters at 52% similarity, which was validated by 16s rrna sequencing to indicate that each phenotypic cluster consisted of a homogeneous set of strains. in another work, by donohue et al. (2007) maldi-tof ms was used for the speciation of unknown environmental water isolates of aeromonas using the m/z signature of known strains of that microorganism. due to its analysis speed and its capability for handling a large number of samples, the authors proffered that this technique could be useful for environmental monitoring. applications of maldi tof ms in the bioremediation field the application of microorganisms to reduce or eliminate hazardous compounds from the environment, so-called bioremediation, is a promising approach as well (vidali, 2001). maldi-tof ms can be used for the rapid screening and identification of site-specific microorganisms present in contaminated environments using their global protein expression (singh, 2006). this allows researchers then to focus on specific microorganism species to evaluate their potential for degradation of chemical hazards. after evaluating their capability, the isolated microorganisms can be used for bioremediation of contaminated and polluted sites. as an example, in the works by (uhlik et al., 2011; lovecka et al., 2015) the identification of bacteria isolated from contaminated soil for bioremediation purposes was performed using maldi-tof ms. in both works, the bacteria were isolated from contaminated soil by using their ability to grow on a solid mineral medium with chemical hazards, pesticides, or biphenyl, as a sole carbon source (santos et al., 2016). afterward, the isolates were identified, some to the strain level, using maldi tof ms. the results obtained were in agreement with the results of 16s rrna sequencing. however, in both studies, there were additional microorganisms that were not successfully identified by maldi-tof ms that may be due to their absence in the database. nevertheless, the authors believe that maldi-tof ms is an important tool for bioremediation research as it allows the rapid and accurate identification of site-specific microorganisms. as the isolated microorganisms can grow using the hazardous exogenous compounds as the sole carbon source, they can act as potential degraders and therefore be used for on-site bioremediation. however, only the work by lovecka et al. (2015) specifically studied the capability of the identified bacteria to degrade the contaminants by measuring the degradation of pesticides and the formation of degradation products. application of maldi-tof ms in identification of bacteria isolated from soil a study by garcia et al. (2021) aimed to measure bacteria indigenous to ddt-contaminated industrial sites in salamanca city, central mexico, as potential candidates for its bioremediation. by using ten-gram soil samples were suspended in 90 ml of saline solution 0.9% m/v and three dilutions were made (1:10, 1:100, 1:1000); 100 µl of each dilution were spread in petri dishes with lb agar enriched with 5 mg/l ddt of technical grade, and incubated at 37 °c for 24 h under aerobic conditions. the colonies were purified by several transfers on the same medium. among twenty-five isolates obtained and identified by maldi-tof ms, bacillus, and pseudomonas species were the most prevalent, accounting for 44% and 20% of all isolates, respectively. the following eight bacteria could grow in the minimum medium in the presence of a ddt concentration of at least 200 mg/l: lysinibacillus fusiformis, bacillus mycoides, bacillus pumilus, bacillus cereus, bacillus marisflavi, bacillus megaterium, lactobacillus adecarboxylata, and serratia fonticola. application of maldi-tof ms in the identification of bacteria isolated from wastewater in an experiment done in 2017 by jančová et al. (2020), in two seasons (summer and autumn), wastewater samples were obtained from six offtake points that are linked to the processing of various dairy products and are crucial for the drainage of wastewater, as it is known, milk and dairy products represent a suitable environment for the growth of microorganisms, that may influence, through their metabolic activity (positively or negatively), the product quality. by using the maldi-tof ms and biochemical methods, identified 77 bacterial strains belonging to 19 bacterial genera out of 89 isolated colonies, plus three fungi – candida parapsilosis metschnikowia pulcherrima, and rhodotorula mucilaginosa – were successfully identified. approximately 10% of the isolated microorganisms were not identified by the use of the maldi-tof ms and biochemical methods. out of 77 isolated and identified bacterial strains, 34 were gram-positive, represented mainly by the genera of lactococcus (35% of identified gram-positive bacteria), staphylococcus (21%), microbacterium (12%), enterococcus (9%), kocuria (9%) and 43 gram-negative mostly species of the genera acinetobacter (35% of identified gram-negative bacteria), pseudomonas (19%), aeromonas (14%), chryseobacterium (9%), enterobacter (7%) and klebsiella (7%). application of maldi-tof ms in identification of bacteria isolated from seawater the diversity of bacteria isolated from qatari seawater by work ashfaq, et. al., (2019), identified using maldi– tof ms includes halomonas aquamarine, halomonas elongata, pseudomonas fragi, vibrio alginolyticus, and vibrio fluvalis (table 1). the match score between 2.3 and 3.00 shows highly probable species-level identification and between 2.0 and 2.29 represents genus-level identification and probable species level of identification. a score between 1.7 and 1.99 indicates probable genus-level identification. as shown in table 1, only 5 out of 20 strains had scores in the lower (1.7–1.99) range, which means that 75% of the 42 haider et al. 2023 / journal of environmental geography 16 (1–4), 38–45. strains were identified up to species level, if we consider the 2.0-2.29 range as a species-level identification. halomonas species belonging to the family of proteobacteria have been reported to be less frequent in coastal areas (sorkhoh et al., 2010). however, it was noted that the species of halomonas were found in most of the offshore and onshore samples tested in this research. halomonas bacteria have ecological importance due to their oil-degrading capabilities (sorkhoh et al., 2010), biomineralization potential through ureolytic activity (arias et al., 2017), biofouling potential, and biofilm formation (ivnitsky et al., 2010; bereschenko et al., 2010; zhang et al., 2011). pseudomonas fragi; other bacteria obtained frequently from different seawater samples, is a psychorophilic gram-negative, commonly found in temperate waters (wang et al., 2017). their ecological importance includes their ability to produce biofilm (wirtanen and mattila-sandholm, 1994) and food spoilage, especially meat, fish, and other marine organisms (tryfinopoulou et al., 2002; ercolini et al., 2007). application of maldi-tof ms in identification of bacteria isolated from air pollution of air has been an emerging issue since the air we breathe carries contaminants, it can affect our health in various approaches. exposure to bioaerosols, holding airborne pathogens leads to various infections, including lung cancer, bronchial asthma, hypersensitivity pneumonitis, toxic reactions, and various cardiac diseases (gorny et al., 2002; fracchia et al., 2006; yassin and almouqatea, 2010). for the prevention and control of air pollution caused by airborne bacteria, rapid, sensitive, and reliable detection techniques are required as well. a study by elbehiry et al. (2019) focused on using maldi biotyper (mbt) for rapid recognition of various microbial air pollutants. five hundred air samples were collected from three localities, including qassim university (150 samples), al-qassim hospitals (250 samples), and poultry slaughterhouses (100 samples). all air samples were collected by impactor air sampler from the indoor and outdoor environment. all samples were cultivated on nutrient and blood agar media for two days and a total of 129 isolates were purified for proteomic analysis using maldi-tof ms, then confirmed by quantitative polymerase chain reaction (qpcr). altogether 119 (92.25%) isolates were identified by maldi-tof ms at the species level with a log (score) value ≥ 2. 000 whereas; 10 (7.75%) isolates were detected at the genus level with score values ranging from 1.7000 to 1.999. the maldi-tof ms was able to identify 93 (72.10%) gram-positive and 36 (27.90%) gram-negative bacterial isolates. the most common genera were staphylococcus (n = 43, 33.33%), escherichia (n = 16, 12.40%), enterococcus (n = 15, 11.63%), and bacillus (n = 15, 11.63%). staphylococcus aureus and escherichia coli were the most frequently identified species (n = 16, 12.40% for each). in general, had been detected 53 (41.10%) various bacterial species in hospitals, 41 (31.79%) in poultry slaughterhouses, and 35 (27.13%) in qassim university, accordingly, the maldi-tof ms was positively adjusted for their fast and accurate identification. in the same context, a study by hernández et al. (2016), collected air samples in a biosafety level 2 laboratory of personal care products. bacterial isolates were identified by (maldi-tof) mass spectrometry and when an organism could not be identified by referencing the appropriate database it was identified by analyzing 16s ribosomal deoxyribonucleic acid (rdna) sequences. the identification results obtained are nineteen bacterial genera from all the sampled sites. gram-positive genera isolated were agrococcus, arthrobacter, bacillus, chryseomicrobium, citricoccus, corynebacterium, exiguobacterium, kocuria, kytococcus, microbacterium, micrococcus, planococcus, planomicrobium, sanguibacter, and staphylococcus. gram-negative genera isolated were pointibacter, pseudomonas, psychrobacter, and skermanella. in total, 85% of bacterial genera were identified by maldi-tof mass spectrometry, and 15% of bacteria genera by 16s rdna sequencing. taxonomic analysis indicated that the genus bacillus, represented by five species, was most common, followed by staphylococcus with four species, and arthrobacter and kocuria with three species. this study and others show that accurate species identification is critical not only for the maintenance of environmental monitoring programs but also to mitigate the risk presented by potential human pathogens with antibiotic multi-resistance in indoor environments (leung and chan, 2006; gálvez-martín et al., 2012). identification of bacteria from extreme environments a study by kopcakova et al. (2014) aimed to analyze the ability of maldi tof ms to identify cultivable microflora from two waste disposal sites in the nontable 1 identification of isolated strains from seawater samples using maldi-tof-ms (ashfaq et al., 2019). identification score halomonas elongata 1.854 halomonas aquamarina 1.78-2.07-2.08-2.04-2.07-2.02-1.96-2.01 pseudomonas fragi 1.93-2.4-2.39-2.36-2.32-2.34-2.33 pseudomonas stutzeri 2.47 vibrio fluvalis 1.75 vibrio alginolyticus 2.04 haider et al. 2023 / journal of environmental geography 16 (1–4), 38–45. 43 ferrous metal industry. despite the harsh conditions (extreme ph values and heavy metal content in red mud disposal sites from aluminum production or high heavy metal content in nickel sludge), relatively high numbers of bacteria were recovered. in both environments, the bacterial community was dominated by gram-positive bacteria, especially actinobacteria. high-quality malditof mass spectra were obtained but most bacteria isolates could not be identified using maldi biotyper software. the overall identification rate was lower than 20%; in two of the environments tested identification rates were lower than 10%. as a dominant bacterial species, microbacterium spp. in drainage water from an aluminum red mud disposal site, bacillus spp. in red mud samples from the same site, and arthrobacter spp. from nickel smelter sludge were identified by 16s rrna sequence analysis. edouard et al. (2012), who used the maldi-tof ms approach mainly for environmental isolates of propionibacterium spp., reported identification rates as low as 18.7 % and proposed database enrichment for the reliable identification of environmental bacteria. koubek et al. (2012) compared maldi-tof ms with two other methods for the taxonomic identification of bacterial isolates obtained from sediment samples contaminated with polychlorinated biphenyls. as with the other method, maldi-tof ms was capable of discriminating between four groups of isolates but was unable to identify them down to the species level. maldi-tof ms has been successfully applied to several taxa, e.g. arthrobacter species (vargha et al., 2006), leuconostoc spp., fructobacillus spp., and lactococcus spp. (de bruyne et al., 2011) or even for archaea or extremophiles (krader and emerson, 2004). in all these reports, however, maldi-tof ms was applied to pure cultures identified by the 16s rrna-sequencing approach. the application of maldi-tof ms in environmental microbiology remains limited. as the primary focus of the maldi tof ms-based methodology is directed toward medically important bacteria, reference database spectra expansion and refinement are needed to improve the ability of malditof ms to identify environmental bacteria, especially those from extreme environments (kopcakova et al., 2014). conclusion maldi-tof ms can be a valuable tool in the field of environmental microbiology, it can be used, not only for microorganism identification and differentiation but also for the detection of protein or metabolite biomarkers that can be used as an indicator of the presence of a specific bacterium. this identification is important to study the bacterial community within the environment or to identify contaminant-degrading bacteria. despite these advantages, maldi-tof ms reproducibility is influenced by culture conditions. therefore, it is very important to use the same sample preparation protocol and to guarantee that the analyzed bacteria are all at the same growth stage. additionally, improvements in the protein database should be made to include more environmental microorganisms and to take into account different protein profiles that can be obtained due to 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https://doi.org/10.1007/%20bf03326162 https://doi.org/10.1128/aem.00122-11 introduction materials and methods approach to the methodological concept results maldi-tof ms environmental microbiology applications application of maldi-tof ms in monitoring the microorganisms at specific stresses applications of maldi tof ms in the bioremediation field application of maldi-tof ms in identification of bacteria isolated from soil application of maldi-tof ms in the identification of bacteria isolated from wastewater application of maldi-tof ms in identification of bacteria isolated from seawater application of maldi-tof ms in identification of bacteria isolated from air identification of bacteria from extreme environments conclusion acknowledgement references investigation of the relationship between soil erosion, land cover and hemeroby level in cserépfalu by analysing soil profiles journal of environmental geography 16 (1–4), 83–94. doi: 10.14232/jengeo-2023-44669 issn 2060-467x investigation of the relationship between soil erosion, land cover and hemeroby level in cserépfalu by analysing soil profiles anna dobos1*, tamás péter hegyi2, zoltán zelei2, balázs hegyi3 1department of environmental sciences and landscape ecology, eszterházy károly catholic university, leányka u. 6-8., h-3300 eger, hungary 2institute of geography and environmental sciences, eszterházy károly catholic university,leányka u. 6-8., h-3300 eger, hungary 3coal commission secretariat, eszterházy károly catholic university, leányka u. 6-8., h-3300 eger, hungary *corresponding author: dobos.anna@uni-eszterhazy.hu research article, received 14 may 2023, accepted 26 july 2023 abstract we can measure the effects of anthropogenic processes to the nature in case of hilly agricultural areas with the rate of soil (water) erosion. there is actual question what kind of connection could be shown between the rate of soil erosion, land cover categories and hemeroby levels? how can the intensity of antropogenic effects influence the rate of soil erosion? we did some research work in the north hungarian region, in cserépfalu in 2014. in cserépfalu, the northern areas are under nature conservation and belong to the southern bükk mountains while the southern dissected pediment is the extensive agricultural territory. we described the soil types in the southern areas using the soil description method of fao. we collected data about the rate of soil erosion, the land cover types, slope angle, slope forms, slope aspect and data for the relief conditions too. we could point out the sheet erosion around th e 15 investigated soil profiles and we could found 3 strongly eroded, 8 medium eroded and 4 accumulated soil profiles. the land cover categories were given based on fao category system and topographic map from 1990. our results showed that land cover categories were changed in time and it caused the change of hemeroby levels as well. the intensity of land cultivation in investigated areas was changed. we could point out in some cases that the stronger soil erosion rate was caused by former land cover system. in summary, some former agricultural areas were changed and became as an abandoned area so that the antropogenic effects were decreased in extensive agricultural areas in cserépfalu. our results can be compared with another pediment dissected by valleys where extensive agricultural areas are characteristic in hungary. keywords: soil erosion, land cover categories, hemeroby levels, cserépfalu introduction the emergence of anthropogenic influences in landscapes is a very diverse and multifaceted process that can affect all landscape factors (i.e., geological, geomorphological, soil, hydrological, climate factors, plants and animals). at the same time, landscape factors may react differently and to different degrees to human interventions (szilassi and bata, 2012). landscape factors interact with each other, and changes in one factor can trigger changes in other landscape factors. the extent of anthropogenic impacts on landscape and natural ecosystems is studied by assigning hemeroby levels. the concept of „hemeroby” was introduced in the field of landscape ecology in the 1950s. jalas (1955) used hemeroby categories to measure the degree of human impact, and this category system became a 7and 10-grade scale system (bornkamm, 1980; bastian and schreiber, 1994; csorba, 1995; gabherr et al., 1998; machado, 2004; rudisser et al., 2012; walz and stein, 2014; fushita et al., 2017; csorba et al., 2018). nowadays, the 7-category hemeroby degree has been applied in hungary (kocsis, 2018; csorba et al., 2018) by designating ahemerobic (almost no human impacts / natural), oligohemerobic (weak human impacts / close-tonatural), mesohemerobic (moderate human impacts / managed, regularly disturbed), β-euhemerobic (moderate–strong human impacts / cultivated), αeuhemerobic (strong human impacts / intensively cultivated), polyhemerobic (very strong human impact / intensively transformed) and metahemerobic (excessively strong human impacts / very intensively transformed) areas. this method combines the extent of anthropogenic influences (disturbance) on relief, water, soil conditions, vegetation and land cover. according to novák et al. (2019), one of the most commonly used indicators to detect the state and change of landscapes is the rate of land cover. it is possible with analysing of new corine databases (szilassi, 2003; csorba and szabó, 2009; liska et al., 2017). they draw attention to the fact that at the same time it seems appropriate to examine the state of soils to express the extent of anthropogenic landscape transformation because the influence of 5 landscape factors in the soil is summed up (novák et al., 2019). pinczés (1968, 1978, 1980) investigated the effects of linear erosion on tokaj hill in 1968, soil erosion research in the bodrogkeresztúr semi-basin in 1978 and the effects of certain cultivation branches on soil erosion in 1980. more detailed survey of soils was in hungary in the 1970s and 80s (stefanovits, 1981). at the same time, the quantitative revolution in physical geography research in https://doi.org/10.14232/jengeo-2023-44669 mailto:dobos.anna@uni-eszterhazy.hu 84 dobos et al.2023 / journal of environmental geography 16 (1–4), 83–94. the 1980s and 1990s made it possible to study soil erosion processes used for agriculture at erosion measuring stations and to support their sustainable utilization (pinczés et al., 1978; kertész, 1984, 1992; kerényi, 1985). the purpose of the measurements was to study soil erosion and accumulation (kertész, 1987; góczán and kertész, 1990; kerényi, 1991; lovász, 2000; tóth et al., 2001; jakab et al., 2005; kitka et al., 2008). kertész (2004) also investigated the degree of soil erosion in hungarian landscapes, as well as the types of water and wind erosion. he mentioned types of water erosion as sheet erosion, rill and gully erosion in his studies (kertész, 2004, 2009). the effects of soil frost on erosion was shown by pinczés (1979). huszár (1999) used the epicerotop method to determine soil erosion estimation, while tóth et al. (2001) used the medrush model to analyse soil degradation. mészáros and jakab (2001) applied the universal soil loss equation in erosion studies. in the 2020s, manalja et al. (2021) investigated the effects of soil erosion on the spatial distribution of soil characters in vineyards. it can be seen that the extent of soil erosion and disturbance in hungary has been analysed by numerous studies. overall, it is the best when we can express the degree of anthropogenic transformation with complex point of view and we can use indicators like land cover, vegetation, soil erosion/compaction and relief conditions (novák et al., 2019). the character and changes of hemeroby levels in hungary have been studied at national scale, macro landscape unit, meso and micro landscape unit and settlement levels so far (kocsis, 2018; csorba et al., 2018; novák et al., 2019; szilassi and bata, 2019). based on the previous research results, we can show what kind of hemeroby level or category change were appeared in the recent study area, in cserépfalu. due to its dual micro landscape units’ extent (bükk and bükkalja micro landscape units), the individual studies mention 2 different categories of hemeroby in connection with the settlement. in the national atlas of hungary prepared during the national survey (kocsis, 2018; csorba et al., 2018), the northern areas of cserépfalu protected by bükk national park were classified as mesohemerobic (disturbed), while the southern, extensivelly cultivated areas were classified as α-euhemerobic (intensively cultivated) level. in case of the micro-landscape survey (novák et al., 2019), between 1990 and 2018, the proportion of land cover changes with increasing anthropogenic impact was low in the bükk microlandscape unit (less than 0,2% of the area of the microlandscape unit, the national average: 0,7%), while the proportion of land cover changes indicating a weakening anthropogenic effect showed a moderate value (0,4-0,8% of the area of the micro-landscape unit, national average: 1,3%). the proportion of land cover changes with increasing human impact was medium in the microlandscape unit of bükkalja (0,4-0,8% of the area of the micro-landscape unit, national average: 0,7%), while the rate of land cover changes indicating weakening anthropogenic effects showed a medium value (0,8-1,7% of the area of the micro-landscape unit, national average: 1,3%). based on the sudy of csorba (2021), the bükk micro-landscape unit, evaluated from the point of view of human strength, was classified into mesohemerobic, i.e. treated, moderately disturbed category, while the bükkalja micro-landscape unit was classified into the αeuhemerobic category, i.e. intensively cultivated agricultural areas. szilassi and bata (2019) examined naturalness equivalent to the concept of hemeroby (hill et al., 2002) using 4 landscape metric indicators. the 4 landscape metric indicators (lpi – largest pach index, np – number of paches, mps – main pach size, awmpfd – area weighted mean patch fractal dimension) were calculated using the 1:100 000 scale corine digital land cover database (eea. 2000) using the vlate (vector-based landscape analyses tools) add-on panel of arcgis software for the years 1990, 2000 and 2006. on their maps, the evaluated areas and settlements can be easily traced at county level as well. between 1990 and 2000, in cserépfalu, part of borsodabaúj-zemplén county, the hemeroby level decreased based on 4 landscape metric indicators, and the sum of changes in landscape metric indices was lower than -50%, which indicated a significant decreasing hemeroby level. between 2000 and 2006, however, landcape metrics showed uncertainty about changes in hemeroby levels, with changes in landscape metric indices totalling less than -50%, suggesting a significantly declining hemeroby level. overall, the level of hemeroby decreased significantly between 1990 and 2006. about half a year ago, we studied the changes in historical land use and the changes in hemeroby levels in relation to cserépfalu in landscape historical and gis methods (dobos and utasi, 2022). at the same time of the first and second military surveys (1763-1787; 18061887), a three-category land use system emerged in cserépfalu. the 1990 map was made after change of regime in 1989, but it still basically indicates the legacy of the socialist farming system in the landscape, while the peculiarities of today’s post-regime land use system were shown in the corine land cover 2012 survey. overall, it can be shown that the original feudal three-category land use system (with arable land, forestry and vineyards) (military survey i. and ii.: 1763-1787; 1806-1887) has changed into a more diverse, multi-category, mixed land use system in the case of cserépfalu over the past 250 years (dobos and utasi, 2022). in cserépfalu, the spread of nature conservation (forests) protected by the bükk national park and extensive agricultural areas of mixed farming in bükkalja can be traced. based on the hemeroby level, cserépfalu was characterized by predominantly natural, semi-natural and semi-natural conditions in the middle high mountain section in the four periods examined (military surveys i and ii; 1990; 2012). the ahemerobic level is 9.56% 2.9% 12.6% and 12.6%, respectively; β-oligohemerobic levels showed 75.52% 77% 64.57% and 63.40% and α-oligohemerobic levels of 1.19% 5.94% 7% and 11.05%, respectively. in addition, anthropogenic biological effects appeared in foothill areas due to arable cultivation (α-euhemerobic level: 12.71% 12.35% 14.23% and 14.34%, respectively). the growth of the settlement indicates the polyhemerobic level, with a value of 1.61% today. in this study, our aim is to examine in more detail the part of cserépfalu that falls within the area of the dobos et al. 2023 / journal of environmental geography 16 (1–4), 83–94. 85 bükkalja micro-landscape unit, as this is more intensively affected by agricultural cultivation. this area is therefore classified as a α-euhemerobic area in terms of human strength (csorba et al., 2018; csorba, 2021) and an area classified as medium in terms of soil erosion rate and wind erosion (kertész, 2004). based on specific field data on the study area, we intend to explore the relationship among the degree of soil erosion, the type of land cover/land use and the hemeroby level. our research results represent settlement-level, 1:10,000 scale processing. study area in 2014, we carried out 1:10,000 scale field soil description in the settlement of cserépfalu. our study area is administratively located in hungary in the north hungarian region, in borsod-abaúj-zemplén county, in the mezőkövesd micro-region (fig. 1). based on the physical geographical landscape classification, our study area lies in the inner nw carpathians, in the macro-landscape unit of the north hungarian mountains, within that in meso-landscape unit of the bükk mountains, in the micro-landscape unit of the bükk and bükkalja (kocsis, 2018; csorba et al., 2018). the administrative area of the settlement (44.65 km2) is situated in micro-landscape units of the bükk and bükkalja. based on the land use zone system (ángyán, 2003), the northern area is under the nature conservation of the south bükk mountains, while the southern foothill areas of the bükkalja belong to extensive agricultural areas. in hungary, in the foothill areas of cserépfalu, the research of landscape ecological features is mainly linked to the name of zoltán pinczés and his research group. so far, detailed geomorphological mapping of the settlement (pinczés et al., 1993; dobos, 2000, 2002, 2012a), exploration of quaternary sediments (pinczés et al., 1998; dobos, 2000, 2012a), mapping of soil conditions (kerényi, 1991; dobos, 2012a, 2017; dobos et al., 2014), water quality survey (kerényi and pásztor, 1994), assessment of its climatic conditions (kerényi and justyák, 1987), mapping changes in landscape history and land use (dobos, 2012b; dobos and utasi, 2022), as well as nature conservation research and mapping of unique landscape values (dobos, 2012b, 2018) were came true. the mapping of geological conditions is related to the names of balogh (1964) and pelikán (2002). our new research results complement this research series. in this study, we seek to answer the question of what relationship can be detected between soil erosion, land cover/land use categories and hemeroby levels in the surroundings of soil profiles excavated in the settlement. therefore, the aim of our studies is to explore the relationship between the various factors in more detail and on a deeper level, using field data. methods a total of 15 soil profiles were excavated in the dissected bükkalja foothill area. we have summarized our field survey results in the scientific report (dobos et al., 2014). the location of the examined soil profiles was determined so that they appear at all geomorphological levels and on different slope parameters and categories with different land cover (fig. 2). the international soil description methodology makes it possible to map about 30 section identifiers, general soil formation and 37 section description parameters of soil profiles in the field, and to determine the soil type and wrb reference group category of the soil profiles based on the analysis of the data (iuss working group wrb, 2015; novák, 2013). the data collected included the definition of soil types, the degree of soil erosion, the type of land use (land cover), slope angle, slope shape, slope aspect and altitude data. in the surroundings of the soil profiles, sheet soil erosion was observed in places. the evaluation of actual erosion was given by expressing the thickness of the fig.1 the location of the study area, cserépfalu 86 dobos et al.2023 / journal of environmental geography 16 (1–4), 83–94. fig.2 the location of the soil profiles investigated in cserépfalu humous soil layer in % relative to the thickness of the investigated soil profile, and by using a table where the category of erosion degree was given (kerényi, 1991; kerényi and martonné, 1994; novák, 2013). the land cover categories were described on the one hand based on field observations (novák, 2013) and, on the other hand, the previous conditions were described on the basis of 1:10,000 topographic maps from 1990 (cartography, 1990). the tabular categories of karancsi (2001) and csorba et al. (2018) were used to detect the extent of anthropogenic effects (hemeroby levels). the maps presented in figure 1 and 2 were created using arcgis 10.4.1 for desktop. results soil types, morphological and geological data during our research, the 15 investigated soil profiles were selected in places with diverse morphological, geological and soil conditions in cserépfalu, taking into account the different appearance of land use types (fig. 2). table 1 shows where 15 soil profiles were excavated in the settlement. the soil profiles examined were located in 40% on hilltops/crest, 13% on middle sections of slopes, 7% on valley bottom, 33% on alluvium and 7% on lower slopes (table 1). in the hilltop/crest category, older, younger foothill surfaces and fluvial terrace levels also appeared. the bedrock of the soil profiles is 40% rhyolite tuffs (volcanic rock) and 60% clay; clay, gravel, pebble; clay and pebble or clay and gravel (sedimentary rock). the wrb reference group (fao, 2006) and the definitions of main soil type, soil type and soil subtype based on the hungarian soil classification system (murányi et al., 1989; novák, 2013) were summarized in table 3. the wrb reference groups for the soil profiles excavated in our study area were varied (fig. 3). according to the fluvial and hilly character of the area, most soils were classified into the category of fluvisols and cambisols category. in addition, the following types were discovered: leptosols, umbrisols, regosols, antrosols and luvisols (dobos et al, 2014). the analyses of wrb reference group and soil types was based on the following characters: depth and name of genetical soil horizons, horizon boundary, soil colour (munsell), texture, soil structure, ph and caco3-content (table 2). taking into account the hungarian soil classification (stefanovits, 1981; novák, 2013) it can be stated that the main soil types indicated stony soils (20%), casting and alluvial and slope soils indicating the legacy of fluvial surface formation (40%), anthropogenic soils indicating anthropogenic effects (7%) and brown forest soils (33%) indicating earlier significant forest cover values in the fragmented hilly (foothill) area (table 3). the classic soil classification system from stefanovits (1981) did not condider anthropogenic soils, and here we used novák’s book to define these soils. at the level of soil types, rocky soils here were represented by erubase and ranker soils (20%). among the alluvial and slope soils, humous alluvial soils (33%) and slope soils (6%) can be detected in the soil profiles. the soil profile excavated on the built area indicates the presence of anthropogenic soils (7%) and anthropogenic influences. among the brown forest soils, the brown forest soil with clay illuviation (7%) and the ramann brown forest soil (27%) appeared in the area. at the level of pedological subtypes, erubase soils indicate the volcanic origin of rhyolite tuffs. the meadow humous alluvial soils, the humous alluvial soils and the slope soils of the forest refer to the relief of the hilly area divided by valleys on the one hand, and the nature of the former land cover on the other. brown forest soils are represented by non-podzolic brown forest soils and ramann brown forest soils with calcareous character. fig.3 the distribution of wrb reference groups in case of investigated soil profiles in cserépfalu. the numbers in the figure represent the number of soil types described. dobos et al. 2023 / journal of environmental geography 16 (1–4), 83–94. 87 results of the rate of soil erosion for the excavated soil profiles, the relationship between slope angle, expected risk of erosion and the degree of soil erosion that can actually be detected was examined (table 4). based on the degree of erosion risk associated with the slope value (table 4, fig. 4), it can be shown that 7% of the soil profiles examined are medium or high; 60% have a small to medium risk of erosion. for 33% of soil profiles, there was no detectable risk of erosion. in fact, sheet erosion can be detected in the surroundings of the 15 investigated soil profiles. accelerated soil erosion can be caused by improper land use, improper treatment and cultivation techniques, overgrazing or destruction of natural vegetation (novák, 2013). in addition, soil erosion can be caused by water and wind erosion, sediment accumulation and mass movements. the evaluation of sheet erosion was given by expressing the thickness of the humous soil layer as % of the thickness of the investigated soil profiles (kerényi, 1991; kerényi and martonné, 1994; novák, 2013). of the 15 soil profiles, 20% had strongly eroded soils and 53% had moderately eroded soils. however, 27 % of soil profiles showed accumulation trends (table 3, fig. 5). if we compare figures 4 and 5, it can be seen that the actual erosion rate for steeper slopes exceeded the amount of erosion that can occur associated with slope angle. this is especially striking for the category of strongly eroded soils. 60% of the soil profiles examined can be considered inherently small to medium erosion hazards and 33% are erosion-free areas based on only slope angle. when examining soil erosion, on the one hand, the degree of erosion risk associated with the slope value was given taking into account the slope angle (várallyay and fórizs, 1966), and on the other hand, a specific soil erosion rate was calculated for specific soil profiles (kerényi, 1991; kerényi and martonné, 1994; novák, 2013). based on our results, the actual erosion rate of steeper slopes exceeded the amount of erosion associated with slope angle. this was particularly marked for the category of heavily eroded soils, with a value of +13%. in reality, the actual erosion rates of moderately eroded and non-eroded soil profiles were lower with values of 7% and 6% in 2014 and 2023. in the administrative area of cserépfalu, we can usually find moderately eroded hilltops, in one case (cs014) the summit level was strongly eroded (table 4). floodplains show the accumulative tendencies of landforms due to sediment accumulation during the pleistocene and holocene period. the soil profiles of csf003 and csf004 each show a soil profile in the table 1 topographical, geological and relief data of investigated soil profiles in cserépfalu code for soil profile topographical situation relief slope category (%) baserock coordinates csf001 the summit of nyomó hill the crest of the hill (older pediment surface) 5-12% rhyolite tuff n 47°57’0.96” e 20°31’0.68” csf002 nyomó hill, the middle southern slope middle slope 12-17% rhyolite tuff n 47°56’49’0.9” e 20°31’4,76” csf003 valley bottom between the nyomó hill and the őr hill valley bottom 5-12% weathered rhyolite tuff n 47°56’34.45” e 20°31’27.82” csf004 alluvium of the hór stream at the southeastern rim of the kerek hill alluvium 5-12% clay, gravel, pubble n 47°57’0.85” e 20°31’59.14” csf005 the lower part of western slope in the ispán-szél lower slope 5-12% clay n 47°57’14.77” e 20°32’13.65” csf006 the rim of alluvium of the hór stream, at the southeastern boundary of cserépfalu alluvium 0-5% clay, gravel n 47°56’10.90” e 20°32’15.13” csf007 the area of the summit of ispán-szél the crest of the hill (younger pediment) 0-5% clay, pebble n 47°57’16.69” e 20°32’19.51” csf008 alluvium of the hór stream, next to the bed channel alluvium 0-5% clay, pebble n 47°57’11.90” e 20°32’10.68” csf009 the rim of the hór stream, alsó-rét alluvium 5-12% clay, gravel n 47°55’39.86” e 20°32’4.10” csf010 the rim of alluvium of the hór stream, alsó-rét alluvium 5-12% pebble, gravel, silty clay n 47°55’54.57” e 20°31’52.42” csf011 the middle western slope in galagonyás the middle slope (younger pediment) 5-12% sand, weathered rhyolite tuff n 47°56’30.83” e 20°32’27.69” csf012 the summit of the galagonyás the crest of the hill (younger pediment) 5-12% rhyolite tuff n 47°56’36.16” e 20°32’40.14” csf013 the summit of the gyűr hill the crest of the hill 5-12% clay n 47°55’46.70” e 20°31’3.04” csf014 the summit of the kerek hill the crest of the hill (younger pediment) 0-5% weathered rhyolite tuff n 47°57’12.68” e 20°31’36.30” csf015 the summit of the csurdoka the crest 0-5% clay n 47°56’6.95” e 20°31’36.80” 88 dobos et al.2023 / journal of environmental geography 16 (1–4), 83–94. vicinity of which strongly or moderately eroded soils can be detected on the valley floor or alluvium. this trend can be explained by earlier cuts in the stream bed and by the higher intensity of stream erosion. results of investigated land cover / land use categories the land use and land cover categories recognizable in the surroundings of the soil profiles were described on the basis of the 1:10,000 topographic map of 1990 and the fao category system (fao, 2006) in 2014 and 2023. in 1990, more active land cultivation was typical in the surroundings of the soil profiles. the environment of the soil profiles was characterised mainly by cultivated arable land (80%) and vineyards (20%) (fig. 6). during the soil description period (2014) and 2023, we were able to register abandoned areas and arable lands mainly in our study area (fig. 7). if we compare the data in figures 6 and 7, we can see that the share of arable land decreased from 80 % to 46 % over 24 years. the share of vineyards has also decreased. land use became more diverse, but a smaller proportion of areas were under continuous agricultural cultivation. abandoned areas (40%) and mowed meadows (7%) also appeared. thus, table 2 results of the soil description in cserépfalu horizon depth [cm] ph caco3 [%] soil colour (munsell) horizon depth [cm] ph caco3 [%] soil colour (munsell) csf001 csf002 a 0-20 7 0 10yr 3/4 a 0-60 6 0-2 10yr 4/3 (c) 20 10yr 6/2 10yr 5/3 b 60-83 6,5 0 10yr 5/4 bc 83-100 7 0 10yr 5/6 c 100 csf003 csf004 a1 0-30 7 0-2 10yr 3/4 a1 0-30 7 0-2 10yr 4/4 a2 30-52 7 0-2 10yr 4/2 a2 30-100 7 0-2 10yr 3/6 b1 52-109 6 0-2 10yr 4/4 b1 100-120 7 0-2 10yr 5/4 b2 109-150 7 010yr 5/4 b2 120-160 7 0-2 10yr 5/4 c 180 7 0-2 10yr 5/4 10yr 6/4 bc 160-183 6 0-2 10yr 5/4 c 183 csf005 csf006 a1 0-37 7 0-2 10yr 3/2 agy 0-15 7 10-25 10yr 4/2 a2 37-55 7 0-2 10yr 3/3 a 15-55 7 10-25 10yr 4/2 b1 55-107 7 0-2 10yr 3/2 b 55-110 7 10-25 10yr 4/2 b2 107-148 7 0-2 10yr 3/4 a 110-148 7 10-25 10yr 4/3 b3 148-181 7 0-2 10yr 2/2 b 148-195 7 2-10 10yr 4/3 b4 181-203 7 0-2 10yr 4/4 b 195 6,5 2-10 csf007 csf008 asz 0-16 7 0 10yr 3/2 aakk1 0-23 8 10-25 10yr 4/6 a 16-34 7 0-2 10yr 3/3 aakk2 23-60 8 10-25 10yr 4/6 b 34-72 7 0-2 10yr 3/3 a1 60-80 8 2-10 10yr 3/4 bc 72-108 7 0-2 10yr 3/4 a2 80-105 8 2-10 10yr 3/6 b 105-135 8 2-10 10yr 4/3 c 135-155 8 10yr 3/4 csf009 csf010 aakk 0-24 6 0-2 10yr 4/2 aakk1 0-27 8 10yr 4/3 a 24-69 6 0-2 10yr 3/3 aakk2 27-45 8 10yr 4/4 ab 69-94 7 0-2 10yr 3/3 a1 45-80 8 10yr 3/2 b 94-120 7 0-2 10yr 3/1 a2 80-122 8 10yr 3/1 bc 120-160 7 0-2 10yr 3/2 b1 122-155 7,5 10yr 2/1 c 160 7 0-2 10yr 3/3 b2 155-190 7 10yr 3/3 c 190 7 10yr 3/4 csf011 csf012 a 0-20 4,5 0-2 10yr 4/3 ap 0-24 7 10-25 10yr 3/4 ab 20-26 7 0-2 10yr 4/3 10yr 4/4 tuff-rubble 24-40 7 10-25 10yr 4/3 b1 26-37 7 0-2 10yr 5/3 a 40-60 7 0 10yr 4/2 b2 37-68 7 0-2 10yr 6/3 ac 60-92 7 0 10yr 4/2 b3 68-92 7 0-2 10yr 5/3 c 92 0 b4 92-130 8 0-2 10yr 5/2 bc 130-166 8 10-25 10yr 4/2 csf013 csf014 ap 0-20 7 0 10yr 3/2 ap 0-22 7 10yr 3/3 a1 20-60 7 0-2 10yr 3/3 a 20-60 6 0-2 10yr 3/4 a2 60-120 7 2-10 10yr 3/2 ab 60-120 7 0-2 10yr 3/4 b1 120-150 7 2-10 10yr 4/3 b1 120-150 8 10-25 10yr 5/4 b2 150-175 8 10-25 10yr 5/6 b2 122-146 8 >25 10yr 5/4 c 175-205 8 >25 2.5 yr 4/8, 10 yr 6/3,10 yr 8/2 b3 146-190 8 2-10 10yr 6/2 c 190 csf015 ap 0-18 8 2-10 10yr 3/2 a 18-61 8 2-10 10yr 4/2 b 61-121 8 >25 10 yr 8/1, 10 yr 4/6, 2.5 y 7/1 c 121-135 8 >25 2.5 y 7/1 dobos et al. 2023 / journal of environmental geography 16 (1–4), 83–94. 89 the land cultivation intensity of the examined areas has changed. the results of the land cover/land use categories in the surroundings of the investigated soil profiles show the emergence of a more diverse and fragmented landscape in 2014 and 2023 compared to 1990. at the same time, it is interesting that the land cultivation intensity of the examined areas has changed, as the share of arable land decreased by 34%, while the share of vineyards decreased by 13%. today, 47% of the soil profiles examined are abandoned areas or mowing meadows. results of investigated hemeroby levels in the surroundings of the excavated soil profiles, the hemeroby level, i.e. the strength of the landscaping effect of human activity, was determined by karancsi (2001) and the categories of the national atlas of hungary (csorba et al., 2018; kocsis, 2018) (table 5). in 1990, β-euhemerobic level (cultivated area) can still be detected in the surroundings of 13 soil profiles, while α-euhemerobic level (intensively cultivated area) can be detected in the surroundings of 2 soil profiles (fig. 8). by 2014, the situation had changed (fig. 9). in parallel with the land cover values, it can be observed that in the surroundings of 6 soil profiles previously showing β-euhemerobic level, cultivation was abandoned and abandoned areas were formed, while in 2 cases a category decrease can be registered and in the surroundings of one profile, in addition to the cultivated area (β-euhemerobic level), we were able to detect the intensively cultivated αeuhemerobic level by planting vines. there were no major changes between 2014 and 2023. overall, by 2014 and 2023, former cultivated areas were abandoned in more places, thus the intensity of anthropogenic influences has decreased in agricultural areas in cserépfalu (fig. 9). discussion previous research results showed that anthropogenic impacts on the landscape have generally increased in hungary due to the increasing extent of agricultural areas on the one hand and built-up areas on the other (csorba et al., 2018; kocsis, 2018). our research results also showed these tendencies in the field of cserépfalu in the research based on landscape history. according to the land use results covering the whole area of the settlement, the hemeroby level increased in the bükkalja micro-landscape unit of the settlement until 2012 compared to previous historical centuries, and the degree of landscape fragmentation also increased (dobos and utasi, 2022). the number of landscape patches has also been steadily increasing over the past 250 years. at the same time, the results of soil profiles analyse comparing several years of data and other landscape factors at settlement level already support the results of szilassi and bata (2019), because from 2014 they indicate a decrease in the hemeroby level in the settlement. the table 3 the classification of genetic soil types based on fao and hungarian soil classification systems in case of surveyed soil profiles in cserépfalu (dobos et al., 2014.) code for soil profile cserépfalu (csf) wrb reference group (fao, 2006) main soil type soil type soil subtype the rate of soil erosion (kerényi, 1991; kerényi and martonné, 1994; novák, 2013) based on hungarian soil classification system (murányi et al., 1989; novák, 2013) csf001 leptosols stony soils erubase and ranker soils erubase soil moderately eroded csf002 umbrisols stony soils erubase and ranker soils erubse soil moderately eroded csf003 fluvisols alluvial and slope soils humous alluvial soils meadow humous alluvial soils strongly eroded csf004 fluvisols alluvial and slope soils humous alluvial soils meadow humous alluvial soils moderately eroded csf005 regosols alluvial and slope soils slope soils forest’s slope soils moderately eroded csf006 antrosols anthropogen soils anthropogen soils accumulated csf007 luvisols brown forest soils brown forest soils with clay illuviation non-podzolic brown forest soils with clay illuviation moderately eroded csf008 fluvisols alluvial and slope soils humous alluvial soils meadow humous alluvial soils accumulated csf009 fluvisols alluvial and slope soils humous alluvial soils humous alluvial soil accumulated csf010 fluvisols alluvial and slope soils humous alluvial soils meadow humous alluvial soil accumulated csf011 cambisols brown forest soils ramann brown forest soils ramann brown forest soil strongly eroded csf012 umbrisols stony soils erubase and ranker soils erubase soil moderately eroded csf013 cambisols brown forest soils ramann brown forest soils ramann brown forest soil moderately eroded csf014 cambisols brown forest soils ramann brown forest soils ramann brown forest soil strongly eroded csf015 cambisols brown forest soils ramann brown forest soils ramann brown forest soil moderately eroded 90 dobos et al.2023 / journal of environmental geography 16 (1–4), 83–94. differences observed can also be explained by the fact that our designated soil profiles provide data around a given point, and do not examine individual factors based on complete area coverage. we agree that land cover and soil condition (soil erosion) can be good indicators for examining the degree of anthropogenic transformation (novák and incze, 2018; novák et al., 2019). the degree of hemeroby level detectable on the basis of land cover usually yields results that are well suited for national, large, meso or micro-landscape unit examinations. table 4 the parameters of slope angle, the risk of erosion and the actual soil erosion in excavated soil profiles in cserépfalu. code for soil profile slope angle (%) the rate of soil erosion risk based on slope angles (várallyay and fórizs, 1966) the rate of soil erosion based on actual investigation of soil profile relief, slope position csf001 5-12% small, medium moderately eroded crest csf002 12-17% medium, high moderately eroded middle slope csf003 5-12% small, medium strongly eroded valley base csf004 5-12% small, medium moderately eroded alluvium csf005 5-12% small, medium moderately eroded lower slope csf006 0-5% no accumulated alluvium csf007 0-5% no moderately eroded crest csf008 0-5% no accumulated alluvium csf009 5-12% small, medium accumulated alluvium csf010 5-12% small, medium accumulated alluvium csf011 5-12% small, medium strongly eroded middle slope csf012 5-12% small, medium moderately eroded crest csf013 5-12% small, medium moderately eroded crest csf014 0-5% no strongly eroded crest csf015 0-5% no moderately eroded crest fig.4 the rate of soil erosion risk based on slope steepness in case of the investigated soil profiles. fig.5 the de facto pointed out soil erosion rate in the investigated soil profiles. fig.6 the land cover categories showned by surroundings of investigated soil profiles in cserépfalun in 1990. fig.7 the land cover categories showned by surroundings of investigated soil profiles in cserépfalun in 2014 and 2023. dobos et al. 2023 / journal of environmental geography 16 (1–4), 83–94. 91 these studies are generally based on processing the corine database. our research results show that only these data are less applicable at settlement level, even though the basic economic planning level is of settlement character. our results reflect that when processing a specific, smaller study area, other local landscape factors have a more significant influence on the research results. in the case of smaller-scale processing, we cannot ignore the mechanism of influence between certain geological, relief and pedological conditions, the farming methods affecting the area and their consequences. the results of our present study have produced gapfilling results in more detailed, 1:10 000 scale investigations. the practical agricultural soil knowledge map of cserépfalu was completed in 1961 (grúz, 1961). the soil description carried out with fao's international soil description method in the case of cserépfalu based on the analysis of 15 soil profiles yielded new results and indicated the diverse soil conditions compared to the previously explored brown forest soils. when presenting soil erosion trends, several geological and topographical parameters were included in the analysis. as we used the new soil description method, we were able to collect data on the spatial distribution of land cover/land use categories table 5 determination of genetic soil types in case of investigated soil profiles in cserépfalu; the former (1990) and actual (2014, 2023) land cover categories and hemeroby levels in surroundings of investigated soil profiles. code for soil profile (csf) wrb reference group (fao, 2006) soil subtype based on hungarian soil classification system (novák, 2013) former land cover category (1990) land cover category in 2014 and 2023 degree of hemeroby – former (1990) degree of hemeroby in 2014 and 2023 csf001 leptosols erubase soil arable land abandoned area β-euhemerobic csf002 umbrisols erubase soil vine-yard arable land, fresh arable land α-euhemerobic β-euhemerobic csf003 fluvisols meadow humous alluvial soil arable land abandoned area β-euhemerobic csf004 fluvisols meadow humosu alluvial soil arable land arable land (maize) β-euhemerobic β-euhemerobic csf005 regosols forest soils, slope soil arable land abandoned area β-euhemerobic csf006 antrosols arable land abandoned area β-euhemerobic csf007 luvisols non-podzolic brown forest soils with clay illuviation arable land abandoned area β-euhemerobic csf008 fluvisols meadow humuos alluvial soil arable land mowed meadow β-euhemerobic mezohemerobic csf009 fluvisols humous alluvial soil arable land arable land (maize) β-euhemerobic β-euhemerobic csf010 fluvisols meadow humous alluvial soil arable land arable land (wheat) β-euhemerobic β-euhemerobic csf011 cambisols ramann brown forest soil arable land abandoned area: shrubs, grassy land β-euhemerobic csf012 umbrisols erubase soil vine-yard arable land α-euhemerobic β-euhemerobic csf013 cambisols ramann brown forest soil arable land arable land (wheat) β-euhemerobic β-euhemerobic csf014 cambisols ramann brown forest soil arable land arable land (maize) β-euhemerobic β-euhemerobic csf015 cambisols ramann brown forest soil vine-yard arable land: wheat and vineyard α-euhemerobic β-euhemerobic and α-euhemerobic fig.8 the hemeroby levels pointed out in the surroundings of the investigated soil profiles in cserépfalu in 1990 fig.9 the hemeroby levels pointed out in the surroundings of the investigated soil profiles in cserépfalu in 2014 and 2023 92 dobos et al.2023 / journal of environmental geography 16 (1–4), 83–94. and we were able to compare this with the previous conditions from 1990 (cartography, 1990). in parallel with the land cover values, the hemeroby levels also decreased, on the one hand cultivation was abandoned in the surroundings of several soil profiles showing βeuhemerobic levels, and on the other hand a category decrease could be detected in the surroundings of 2 soil profiles. the intensity of anthropogenic influences has decreased nowadays in agricultural areas in cserépfalu. it is difficult to compare our results with other hungarian settlements, because such results have not yet been obtained using a new soil description method. our results provide good data for editing hemeroby maps and environmental management maps, which can be used well in regional planning and can improve the practice of landscape design based on local conditions (csorba, 1995). conclusions the aim of this article was to examine the relationship between soil erosion, land cover and hemeroby levels in the area of cserépfalu, a settlement in northern hungary. during our research, we chose such a method that made it possible to classify 15 soil profiles based on international and national soil classification system, to explore more soil types compared to previous results, and to describe more detailed data about the soil profiles. anthropogenic soils were also detected in the plot. more detailed results show that the geomorphological position of soil profiles, slope position and past and present land use categories strongly influenced the rate of soil erosion risk. the complete exploration of the soil properties in soil profiles showed that the actual soil erosion rate is usually one half or one category higher than the degree of soil erosion risk adjusted to the slope angle value. we could not show a strong relationship between soil erosion and land cover and hemeroby levels. the greatest soil erosion was detected at valley bottom (csf 003, 5-12%), younger foothill slope (csf 011, 5-12%) and at summit level (csf 014, 0-5%). in the first two cases, abandonment of arable land was recorded, while in the last area arable cultivation was continuous. moderate soil erosion was shown by abandoned arable land and vineyards. we have seen accumulation in continuous arable and viticultural cultivation, or in abandoned fields. the extent of soil erosion was greatly influenced by previous geomorphological processes and applications of previous land-use categories. however, a closer relationship was found between land cover/land use and hemeroby levels. in continuous arable cultivation, a change in β-euhemerobic level (α β-euhemerobic level or β-euhemerobic level mesohemerobic level) can be observed when a vineyards become arable land or mowed meadow. the proportion of abandoned vineyards and arable land was 40%, where a decrease in α and β-euhemerobic levels was detected. until 2012, the hemeroby level in cserépfalu was continuously increasing in the settlement, and as you can see, after 2012 the hemeroby level decreased until 2023. our research results and method can be applied in foothill areas of similar character, in settlement-level surveys, in extensive or intensive agricultural areas, where soil data are available with the new fao survey. acknowledgement this research work was funded by támop – 4.2.2.a11/1/konv-2012-0016 project. we would like to thank our research possibilities for dr. pajtókné dr. habil. ilona tari who was the head of this project and csaba ruszkai phd who was the project coordinator. references arcgis world 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(in hungarian) walz, u. – stein, c. 2014. indicators of hemeroby for the monitoring of landscapes in germany. journal of nature conservation, 22. 279–289. doi: http://dx.doi.org/10.1016/j.jnc.2014.01.007 https://doi.org/10.1016/j.ecolind.2011.09.027 https://doi.org/10.5069/g9445jdf http://dx.doi.org/10.1016/j.jnc.2014.01.007 introduction study area methods results soil types, morphological and geological data results of the rate of soil erosion results of investigated land cover / land use categories results of investigated hemeroby levels discussion conclusions acknowledgement references