asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 3, 51-55, 2014 http://www.asianonlinejournals.com/index.php/arees 51 an evaluation of physical planning inputs in the process of resettling the inhabitants of flood plain areas of river niger, niger state abubakar, a.n. 1 --suleiman, y. m. 2 1 department of urban and regional planning, school of environmental studies, niger state polytechnic, zungeru, nigeria 2 laboratory of remote sensing and meteorology, department of geography, federal university of technology, minna, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction the flood plains of river niger and kaduna covers about 200 square kilometer. there are 41 settlements scattered within the area with fishing as their means of livelihood. they fall under one district head which is divided into 4 village are [1] table-1. existing settlement hierarchy village head area settlement no of villages household population functional hierarchy order of settlement muregi 21 1335 district headquarters 1 sunlati 10 874 village head dangi 7 680 village head 2 gazhe 3 252 village head total 41 3,141 source: niger state government resettlement scheme [1]. the compounds range between 30 m x 35m to 70 to 75m (table2) table-2. sampled compound sizes observed in the affected area compound dimension observed no of household % distribution 30m x 35m 20 20 40m x 45m 22 22 50m x 55m 47 47 60m x 65m 8 8 70m x 75m 3 3 source: field survey, 2000. table shows 47% of the compound survey has 50m x 55m. this study evaluates the physical planning input in the process of resettling the victims of the flood plain of river niger and kaduna, by the niger state government. evaluation studies of resettlement programmes in african countries have tended to focus on socio-economic considerations and less on physical planning, knowledge of which is useful for promoting programme success. a number of criteria were adopted in the method of evaluation. these were the regional context of the resettlement site; conveniences and adequacy of the site for resettlement; nature of housing delivery for the resettles; and the production base of the new villages. the outcome of the evaluation of the inputs showed that some aspects have shown the potential to influence the success of the programme, such as the location and layout design and the inadequacy of land for residential and farm activities. the study made an attempt to suggest some physical planning corrective measures that will assist the success of the programme, which are captured in the concluding part of the report. keywords: evaluation, physical planning input, criteria, resettlement, corrective measures. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(3): 51-55 52 in recent times, the areas have been threatened by flood annually as a result of kainji, jebba and shiroro dam constructions over the two rivers. this has disrupted the intensive fishing activities. the people have now resulted to farming as a compliment to fishing. average farm size of the farmers as observed is presented on table 3. table-3. average farm size distribution average farm size (hectares) no of respondent % distribution 1.5 25 4 2.5 79 13 3.5 495 83 total 600 100 source: field survey 2000 from the above, the farm size distribution is an evidence of small scale farming. the phenomenon of constant flooding has often washed away homes, farmlands, fish ponds and other commercial facilities as well as displaced the flood plain community. this intimated the niger state government and initiated resettling the victims, at suitable locations away from prone plains 2. procedures and physical planning input physical planning is concerned primarily with orderly and efficient organization of space [2]. in resettlement programmes, it enhances the coordination of all forms of developmental activities by making the fullest and most effective use of available resources [3]. it covers aspect ranging from activities in site selection, site design, land use planning, housing and facilities provision, etc. the physical planning input in the niger flood plain resettlement programme include, site selection, site design, land acquisition and housing provision. the analysis of these inputs was done to establish a base for the evaluation. site selection:two sites were selected, new muregi and chekugi sites. the muregi site covered an area of 136.8 hectares of land and chekugi site has an area of 163.2 hectares of land [1]. the two sites fall within the same geographical region. with particular reference to the niger state capability map, the selected areas are blessed with good environmental conditions that support the cultivation of both cash and food crops. it has nearly level to gently sloping topography conducive for settlement development. site design: two layout plans (proposed muregi and chekugi plans) were designed for the two sites (fig 1 & 2) muregi plan adopted grid iron pattern with integrated hierarchical pattern of roads with 472 uniform plots sizes of 15m by 30m, and covers an area of 136.8 hectares of land with residential plots occupying 21.24 hectares of land and 115.56 hectares for utility, facility services. the proposed chekugi plan, adopted curvilinear design concept and served with integrated hierarchical pattern of road with residential plots occupying 21.15 and 142.05 hectares for utility, facility services. the total land acquired for the whole programme both for residential and agricultural purposes is 300 hectares and 5505 hectares respectively. housing delivery: the resettlement committee proposed 4 options for the community housing provision. these include:(i) gradual construction of dwelling units for the victims by the government (ii) construction of all dwelling units from foundations to floor slap level and allow beneficiaries to continue to finish (iii) allocation of plots to beneficiaries and supplemented with building materials. (vi) allocation of funds and plots to beneficiaries to reduce too much government involvement. option one was adopted by the government. under the option the government is to provide each of the 3,141 household with 3 bedroom semi detached housing unit. 3. methods the 41 settlement affected were ranked into 4 classes (table 1). all the villages in each of the classes were assigned a number. in each class, 3 villages were selected randomly using table of random numbers and questionnaire administered to their inhabitants. 1,000 questionnaires were administered among the selected villages with the help of field assistant. the questionnaire was design to retrieve information on the pattern of socioeconomic activities of the people, their opinion on the resettlement programme. numbers of criteria were adopted in the evaluation. these were limited to regional context of site; conveniences and adequacy of the site, nature of housing delivery and the production base of new villages. 4. results and discussion the regional context of the site: two variables of sites are considered here:site specific attributes and infrastructure support attributes. the site specific is the physical properties of sites, such as terrain, soil fertility; etc as support base for development purposes, while infrastructure support is the existing developments in terms of transportation network, utility, facility and services etc. the terrain in the old settlements areas is generally flat on a height of about 100 meters above sea level and a slope gradient of less than 2% while the new site lie on a gently sloping topography, on a height of 380 meters above sea level and a slope angle of over 4% (fig 3). table-3. slope categories land uses slope standard (%) field observation slope angle old site new site difficult terrain for development 0 – 1% l es s th an 2 % m o re th an 2 % recreational facilities 1 – 3% intensive activities 1 – 4% high density residential 1 – 5% source: planning standard and field survey, 2000. asian review of environmental and earth sciences, 2014, 1(3): 51-55 53 in terms of soil fertility, the old sites are characterized by loamy and clay sediments deposits, good for fadama development under mechanical cultivation, frequent flooding is its main constraints. soil of the new site have deep, well drain to medium fertile soil, capable of sustaining cereal crops and perennial crops with no physical limitation to mechanical cultivations. comparing these variables, soil of the new sites could be accepted. in terms of accessibility, the old sites are only accessible by footpath during the dry season, while new sites are accessible through the two dominant regional roads. from the assessment, the new sites could be appropriate for the resettlement of the victims. this was confirm through the opinion survey (table 4) table-4. households responses to the selected sites opinion household responses % distribution like it 730 73% dislike it 140 14% indifferent 130 13% total 1000 100 source: field survey 2000 the responses therefore is indicative of people willingness to accept the new sites conveniences and adequacy of the site:there are 3,141 households with an estimated population of 26,748 people in the existing settlements of the flood plain (table 5) table-5. present and projected population to year 2010 name of village area present household population year 2000 estimated population year 2000 projected household pop year 2000 projected estimated pop 2010 muregi 1,335 11, 543 1,669 14,429 sunlati 874 7,768 1,093 9,710 dangi 680 5,321 850 6,651 gazhe 252 2,116 315 2,645 total 3,141 26,748 3,927 33,435 source: field survey, 2000 a linear measurement of a sample of 100 household compound plots was made to determine the sizes of plots by individuals household (see table 2). the observed result shows that 47% of the household have average compound plot sizes of 50m by 55 meters. theses size accommodates larger families together with their future needs and activities. only 30m x 15m each were proposed and sites designed for muregi and chekugi. considering the present population, this is grossly inadequate if all the communities are to be relocated, hence neglect in variation of family size. nature of housing delivery: the four proposed options were assessed to determine which would meet the requirements of the victims. the variables uses are: psychological, economic, political, cultural and social functions of a house. one hundred present (100%) weights were allocated to each option proportionally to their roles in a resettlement scheme on a ration 5:4:3:2:1 among the 4 option in descending order of their importance (table 6) table-6. showing the evaluation of alternative option for housing s/n option psychological cultural economical political social total 1. gradual construction of all the dwelling units for the victims 0 0 26.7 20 0 46.7% 2. construction of all dwelling units from foundation to flow slap level and allow beneficiaries to continue to finish 33.3 13.3 0 20 0 66.6% 3. allocation of plots to beneficiaries and supplemented with building materials 33.3 13.3 26.7 0 6.7 80% 4. allocation of funds and plots to beneficiaries to reduce too much government involvement 33.3 13.3 26.7 20 6.7 100% source: field survey, 2000 [1]. the above shows that option four (4) will be more realistic as against option one adopted by the government. essence is to allow them build houses of their choice and maintain their cultural values. this was confirm through opinion survey about government plan to build houses for them (table 7) asian review of environmental and earth sciences, 2014, 1(3): 51-55 54 table-7. household responses to the option adopted by government opinion household responses % distribution welcome it 26 2.6 dislike it 967 96.7 indifference 7 0.7 total 1000 100 source: field survey, 2000 the level of response above is an indicative of people opposing the plan by government to provide houses. the production base of the resettlement:their production base is agriculture farming is the second production activity after the disruption of fishing activities as a result of flooding. average farm size observed shows that 83% have an average of 3.5 hectares of land (see table 3). the committee has proposed and acquired 5505 hectares of farm for the scheme, representing 1.8 hectares of land per person. this is inadequate if we are to consider the present population and its projection to year 2010. the implication of this shall be shortage of farming lands that may lead to land crisis and acute poverty as the communities are resettled as the case in agazera and volta dam schemes [4]. 5. summary and physical planning proposal the study revealed some physical planning lapses in the process of resettlement, such as inadequacy in the size of land acquired for the resettlement and the option adoption for the proposed housing provision. there is therefore, the need for appropriate corrective measures for the success of the programme. this is to ensure a successful resettlement programme for the people. the following attempts were made to estimate both the present and future requirement of landmass for both residential and agriculture purposes. increase the residential land areas:to achieve this, attempt was made to determine land for residential purposes, both for the present and the future requirement. this was based on the observed average ratio of compound sizes of the household made on (table.2). this is translated below. table-8. population and residential/compound size ratio estimate between 2000 -2010 name of villages 2000 2010 number of household observed compound size (0.275ha) projection at 2.5% population residential land muregi 1335 367.1 1669 459.0 sunlati 874 240.1 1093 300.6 dangi 680 187.0 850 233.8 gazhe 252 69.3 315 86.6 total 3,141 863.7 3,927 1,080 source: field survey, 2000 the result shows that the resettlement communities would require 863.7 hectares of land to start with and 1080 hectares of land in 2010 ad as projected. this is against 300 hectares proposed by the resettlement committee. in housing provision, the option adopted by the government will not meet the desires of the beneficiaries based on the result of the evaluation (table 6). thus, option 4 will be more realistic, which will allow them to build houses of their taste, choice and maintaining their cultural values. increase the agricultural land areas:agriculture is the production base of the community. an attempt was made to estimate present and futures requirement of agriculture land. this was based on the average farm size ratio observed in the flood plain area (table 3). this is translated below: table-9. population and agricultural land size ratio estimate between the years 2000 – 2010 name of villages 2000 2010 number of household observed farm ration population and farm sizes projection population projection at 2.5% farm sizes projection at 3.5ha muregi 1335 4671.5 1669 5841.5 sunlati 874 3059.0 1093 3825.5 dangi 680 2380.0 850 2975.0 gazhe 252 882.0 315 1102.5 total 3,141 10,993.5 3,927 13,744.5 source: field survey 2000. from the above table, 10,993.5 hectares, of land is required at the start with 13744.5 hectares projected to 2010 as against 5505 proposed by the communities 6. concluding remarks the government initiative to resettle the people of niger flood plain is a welcome development and it is worth cherishing. how to accomplish these goals remains a great challenging to many discipline amongst which is physical planning. the evaluation of the project has revealed a number of lapses relating to physical planning which if not corrected will result to failure of the scheme. a number of problems have been raised and corrective measures proffered, but the great deal is whether these corrective measures will be implemented. nevertheless, the research has established facts, which will be useful for success of the niger flood plain resettlement scheme asian review of environmental and earth sciences, 2014, 1(3): 51-55 55 references [1] niger state government resettlement scheme, "report of the committee on the resettlement scheme," 2000. [2] a. faludi, a reader in planning theory. london: pergamon, 1973. [3] h. w. donald, urban and regional and municipal public policy. new york: herper and brothers, 1958. [4] r. chambers, the volta resettlement experience. london: pall mail press, limited, 1970. bibliography [1] a. n. abubakar, "an evaluation of the muregi resettlement programme on the flood plain of river, niger state," unpublished m.sc thesis, department of urban and regional planning, abu, zaria, 2004. [2] e. arthur, urban planning concepts, standards and symbols. lagos: amtitop books, nigeria limited, 1997. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 1, 16-18, 2014 http://www.asianonlinejournals.com/index.php/arees 16 seasonal variations of infiltration rates of forest land cover in utisols soils of abini, biase, cross river state of nigeria ukata, samual uka 1 --oluyemi ayorinde akintoye 2 --charles ojong nkpena 3 -- ubong edet harrison 4 1,2 dept. of geography and environmental science, university of calabar, cross river state, nigeria 3 research and planning department, cross river tourism bureau, calabar, cross river state, nigeria 4 dept. of geography and environmental science, university of calabar, cross river state, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction the movement of water into the immediate soil surface either through precipitation, irrigation or other hydrological processes describes the phenomenon of infiltration. it involves three main components of surface entry, movement through the soil surface and reduction of soil storage capacity. the maximum rate at which the soil in any given condition is capable of absorbing water is called infiltration capacity, while infiltration rate on the other hand refers to the amount of water that passes into the ground surface at a given depth, per unit time [2]. akintoye, et al. [3] have also examined the effects of land-use on the infiltration capacity of coastal plain soils of calabar in nigeria. as an important process in the soil phase of the hydrologic cycle, infiltration determines the amount of run -off and supply of water into the soil profile [4]. empirical works have proved the variations in infiltration rates of tropical soils resulting from high rainfall seasonality, parent material and the influence of vegetation. studies by antigha [5] showed marked variations in mean infiltration rates of soils under forested land cover of akamkpa to be between 3.1 and 3.6 cm/hr1 in dry and raining seasons of the year. in ireland, diamond [6] assessed the infiltration capacities of some extensive soils to determine their temporal and spatial variability. the result showed that the initial moisture content at 0.60mm depth was lower during summer than winter, with mean values of 0.38 mm and 0.70 mm. the mean steady infiltration rate (mm hr -1 ) was given as 50.4 mm and 22.1 mm respectively. also, studies by ahn [7] in england revealed seasonal variations of mean infiltration rates to be 0.24 mm and 0.63 mm at summer and winter season to corroborates previous research findings. from the above, an understanding of the moisture regime of soils of the study area depends on the estimate of soil water properties and control of the dynamics of water flow theory in time and space. consequently, this paper this article provides insight into the seasonal variation of infiltration rates of utisol soils, under forest cover in abini, biase, cross river state of nigeria. the annual and seasonal amount of precipitation upon a place, and the soils capacity to absorb same, affects the degree and extent of the occurrence of ecological events, such as overland flow, runoff, erosion, flooding and landslide, quite inimical to land productivity. thus the study investigated the response of forest soils to precipitation intake at different seasons, which is pertinent to landuse planning in both construction and agricultural industries. data from the study were generated through field measurements of the infiltration rates of soils using a cylinder (flooding) inflitrometer designed by hills [1] in two seasons of rainy (september-october) and dry (december-january) respectively, in rural watershed. the result showed seasonal changes in the equilibrium rates of infiltration form 9.6cm/hrt (rainy season) to 8.4 cm/hrt (dry season). this was indeed a hypothetical contrast from the expected ideal situation among infiltration experts, that infiltration values are supposed to soar in dry season than rainy season in the tropics. the factors of soil pore compaction and decline in the rates of biological activities accounted for this. soil compaction reduces the rate of soil water loss through evaporation, enhances ground water conservation and stabilizes the soil structure for diverse benefits to man. afforestation programme is hereby recommended to sustain the regional land ecosystem. keywords: seasonal variation, infiltration rates, ecological events, compaction of pores. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(1):16-18 17 provides information on water availability and moisture retention capacity of soils under forest land cover in abini region at different seasons of the year, which is necessary for land use planning, both in the construction and agricultural industries, with implication for the manufacturing industries. 2. study area the study area is abini, in biase, cross river state of nigeria. it is located between longitude 8 0 06 and 8 0 10’e and latitudes 5 0 00n and 5 0 38n. the area is characterized by humid tropical climate with distinct wet and dry seasons. rainfall amount ranges from 3,500 mm to 4,000 mm per annum. the rainy season falls between april and october, with a short dry spell usually referred to as august break during the month of august [8]. it also has a relative humidity of between 80 and 90 per cent [9]. the temperature is moderately hot and does not fluctuate greatly with a mean range of 27 0 c to 33 0 c [10]. the geologic environment comprise of phyllites, schists with structural features as foliation, joints, fold intrusion, pegmatite and barite. the rocks are uncomfortably overlain by sedimentary sequence of calcareous sandstones with mineral contents of quartz, clay, calcite and fossils occurring as ridges [11]. the soils are mostly derived from cretaceous sediments of eze aku group [12] and are mostly lateritic in the upland area as essential residue products (deposits) formed under distinctive climatic conditions in tropical and subtropical regions. there are also calcareous soils containing quartz, calcite and fossils as dominant minerals. being acted upon by human induced and natural processes, the soils occur in separate, but close ranges as silt loam, silt day, loamy, sand loam and clay loam, with varying textural characteristics of coarse gritty, powdery smooth to sticky and plastic feel. the forest land cover is made up of woody and non-woody plants (parasitic, saprophytic and epiphytic climbers) which constitutes luxuriant and dense tree canopy, shading the soils from the vagaries of nature across seasons. this, in conjunction with other highlighted environmental variables influence the infiltration rates of regional soils at different scales, which can either be detrimental or beneficial to the local land resources. 3. method of study a cylinder (flooding) infiltrometer designed by hills [1] was used for field measurements in both rainy (september –october) and dry (december-january) seasons in rural watershed under forest land cover. a metal tube was driven into the ground to a depth of 10cm with a sledge hammer to avoid lateral flow of water during experiment. care was taken to prevent damage to the soil structure in the process [13]. as a rule, a constant ponding level of 5cm was maintained in the metal tube (ring) throughout the experimental runs. using a timer, readings were taken at various time interval, until a state of equilibrium, which is usually 180 minutes was reached. the experiment was replicated in rainy and dry seasons on the same land cover to determine seasonal variations in the infiltration capacity of the soils table-1. equilibrium infiltration rate of forest land cover in rainy season (september-october) internal (mins) cumulative time (mins) cumulative intake (cm) infiltration rates (cm/hr) 0 0 0 5 5 1.6 12.0 5 10 2.0 11.8 5 15 2.5 10.2 5 20 4.0 12.0 5 25 4.5 11.0 5 30 5.5 11.0 10 40 7.2 11.0 10 50 8.8 11.0 10 60 10.6 11.0 15 75 11.6 10.0 15 90 14.8 9.6 30 120 18.6 9.6 30 150 24.4 9.6 30 180 28.8 9.6 source: authors fieldwork, 2012 table-2. equilibrium infiltration rate of forest landcover in dry season (december-january) internal (mins) cumulative time (mins) cumulative intake (cm) infiltration rates (cm/hr) 0 0 0 5 5 8.2 52.1 5 10 7.6 46.0 5 15 9.8 39.0 5 20 10.8 32.4 5 25 11.8 28.3 5 30 12.4 25.0 10 40 13.4 20.1 10 50 14.4 17.3 10 60 15.2 15.2 15 75 15.4 12.3 15 90 15.8 11.0 30 120 16.2 8.4 30 150 20.4 8.4 30 180 24.6 8.4 source: authors fieldwork, 2013 asian review of environmental and earth sciences, 2014, 1(1):16-18 18 4. result and discussion table 1 and 2 show the equilibrium infiltration rate or the maximum water absorption rate of soils under forest cover at two different seasons of the year. it was discovered at the beginning of experiment in both seasons that soils exhibited strong capillary attraction (sorptivity) for moisture in the subsurface due to increased matrix potential (energy level) within particle surfaces. this gave the high values of infiltration recorded in the first 25-30 minutes. but as water percolated downward (transmissivity), the surface layers became semi saturated and capillary forces diminished and hence the reduction in infiltration rate values as time elapsed. most frequently, the values of (i) decline monotonically and tend to approach asymptotic state known as the final, equilibrium or steady state [4]. the study revealed a decline in the infiltration rate of experimental site from (9.6 cmhr) previously recorded in rainy season to 8.4 cmhr in the dry season. this was a sharp contrast from what obtains in other land uses in ideal situation where intake rate of soil is always higher in dry season, than observed. the factors of decline in soil biological activities and the compaction of soil pore accounted for the behaviour of the soil to its water absorption and transmission rate. this translate to mean that, in dry season, the rate of water loss to the atmosphere (evaporation) occasioned by high solar radiation is lower in forest soils than open or bare land surfaces. this finding is in line with [14, 15] that a good vegetation cover and surface condition greatly influence infiltration rate than soil type and texture. 5. conclusion the response of soil to water absorption according to seasonal variations is demonstrated in this study. values of infiltration runs recorded in rainy and dry seasons in forest land cover revealed a hypothetical contrast from the popular notion among infiltration experts that the dry season readings must always rank higher in all soils under different land covers, especially in the tropics. the ability of forest soils to dynamically indicate a decline in soil biological activities leading to the compaction of pore spaces is nature’s mechanism for reducing water loss to the atmosphere necessitated by litter decay and foliage protection. hence, afforestation programmes should be encouraged as a measure of stabilizing the hydrologic cycle for the benefit of man. references [1] s. hills, entry of water into soil: environmental soil physics. san diego: academic press, 1970. [2] h. m. raghumath, hydrology: principles, analysis and design. new delhi: new age international publishers, 2008. [3] o. a. akintoye, s. u. ukata, and h. i. esomonye, "effects of land-use on the infiltration capacity of coastal plain soils of calabar, nigeria," international journal of applied science and technology, vol. 2, pp. 80-84, 2012. [4] h. donscott, soil physics: agricultural environmental application. iowa: iowa state university press, 2000. [5] n. r. b. antigha, "infiltration characteristics of selected soils in cross river state, nigeria and their implication for sustainable crop production," unpublished ph.d dissertation, university of calabar, nigeria, 2007. [6] j. diamond, "bulk density determination of chloroche country soils," irish geography, vol. 36, pp. 243-248, 2002. [7] p. n. ahn, west african soils. london: oxford university press, 2001. [8] nigeria meteordogical station (nimest), "annual meteorological readings in biase local government area, cross river state, nigeria," calabar nigeria meteorological station (nimest), 2009. [9] w. r. naa, "nigerian airport authority monthly weather chart for calabar," 2006. [10] j. o. ayoade, tropical hydrology and water resources: agbo areo publishers, 2004. [11] b. n. ekwueme, field geology and geological map production and interpretation. calabar: bachudo science, 2004. [12] l. c. amajor, "the eze-aku sandstone ridge of south eastern nigeria," nigeria journal of mining geology, vol. 23, pp. 17-26, 1987. [13] s. u. ukata, "the effects of landuse on infiltration capacity of soils in biase, cross river state, nigeria," an unpublished phd dissertation, department of geography and environmental science, university of calabar, calabar, nigeria, 2012. [14] f. o. akintola, "the parameters of infiltration equations of urban land surfaces," unpublished ph.d dissertation, university of ibadan, nigeriau, 1974. [15] t. a. saiko and i. s. zonn, "landuse and management impacts on structure and infiltration characteristics of chio," soil science, vol. 168, pp. 167-177, 2003. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 1, 5-7, 2014 http://www.asianonlinejournals.com/index.php/arees 5 indoor and outdoor gamma dose rate exposure levels in major commercial building materials distribution outlets in jos, plateau state-nigeria d.i.jwanbot 1 --m.m.izam 2 --g.g. nyam 3 --m.yusuf 4 1,2,4 department of physics, university of jos-nigeria 3department of physics, university of abuja-nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction radioactive materials containing radionuclides of natural origin are known as norm (naturally occurring radioactive materials). some minerals have significant levels of natural radionuclides that are extracted and processed with other elements. some industries involve processes that concentrate natural radionuclides and then may cause some risk to people if their exposure are not under control. these naturally radioactive materials that are concentrated by some industries are known as tenorm (technological enhanced naturally occurring radioactive materials). although there is a conceptual difference between norm and tenorm, sometimes the term norm is used referring to tenorm. tenorm is found in some effluent flows and waste from non-nuclear industries, for example in metal residues, scales sludge and fluid. the materials, the by-products and final products from processes may enhance the exposure of workers and members of the public. the most important radioactivity source in tenorm is due to the presence of isotope produces of the uranium and thorium decay chain. all building materials contain various amounts of natural radioactive nuclides. materials derived from rocks and soils contain mainly natural radionuclides of uranium 238 u and thorium th series, and their radioactive isotope of potassium 40 k. the external radiation exposure is caused by the gamma emitting radionuclide which is the uranium series mainly belonging to the decay chain segment starting with 226 ra. the internal (inhalation) radiation exposure is due to 222 rn and marginally to 220 rn and their short lived decay products, exhaled from building materials into the air. naturally occurring radioactive materials a widespread substance that can be found everywhere in the environment including rocks, soil water, air and also tissues of living things. there are no ways to avoid the presence of natural radionuclide since its presence is from the formation of the earth. man is continuously exposed to ionizing radiation from naturally occurring radioactive materials. the origin of these materials is the earth crust, but they find their way into building materials, air, water, food and human body itself. measurement of activity concentrations of radionuclides in building materials is important in the assessment of population exposure, as most individuals spend 80% of their time indoors [1]. in many parts of the world, building materials containing radioactive materials have been used for generations. as individuals spend more than 80% of their time indoors, the internal and external radiation exposure from building materials creates prolonged exposure situations [2]. recycled industrial bycertain types of building materials are known to be radioactive. exposures to indoor and outdoor radiation like exposure to any other type of ionizing radiation result in critical health challenges. the measurements of the indoor and outdoor gamma dose rate exposure levels of various types of building materials in the major commercial building materials distribution outlets in jos plateau was carriedout. a total number of 56 shops where building materials are sold were surveyed using gamma-scout (model gs2 with serial number a20). the range of the radiation levels were: (0.258 0.264) msv/yr and (0.218 0.226) msv/yr for floor titles indoor and outdoor respective, (0.226 – 0.25 –0.250) msv/yr and (0.210 0.214) msv/yr for pvc ceiling indoor and outdoor respectively. the average total annual effective doses due to outdoor and indoor gamma exposures were 1.80msv (floor tiles) and 1.64msv (wall tiles) while for wash hand basin was 1.69msv/yr, white cement and pvc pipes materials recorded the lowest annual effective dose amongst all the others, which is above 1msv/yr (the acceptable limit for the general public). hence these could pose some health hazards to the occupants of these store/shops. keywords: dose rate, building materials, indoor gamma exposure, outdoor gamma exposure, exposure lev level. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(1): 5-7 6 products containing technologically enhanced natural occurring radioactive materials are extensively used in the construction industry. coal ash produced as waste in the combustion of coal, is used as an additive to cement in concrete and in some countries bricks are made from fly ash. coal slag is used in floor structures as insulating filling material. phosphogypsum, a by-product in the production of phosphorous, fertilizer is used as building material and red mud, a waste from primary aluminum production is used in bricks, ceramics and tiles [3, 4]. building materials cause direct radiation exposure because most of them contain naturally occurring radioactive materials mainly radionuclides from 226 ra and 232 th decay chains and 40 k .the world wide average indoor effective dose due to gamma rays from building materials is estimated to be about 0.4 msv per year [5]. elevated indoor external dose rates may arise from high radionuclide content in building materials [6-10]. generally natural building materials reflect the geology of their site of origin. however, elevated levels of natural radionuclides causing annual doses several msv have been identified in some regions around the world e.g. in brazil, france, india, nigeria and iran [11]. this external radiation exposure caused by gamma emitting radionuclides in building materials can be assessed either by direct exposure measurements in the existing buildings or by radionuclide analyses of building materials with dose rate modeling. 2. materials and method the rwang-pam building material shops in jos north and that of building materials, bukuru in jos south were selected for this study because they are the largest building materials distribution outlets in plateau state. it is always full of daily activities for customers who come from different towns in the state and also from neighboring states to buy different building materials for construction purposes. these building materials are usually displayed at the front of their shops while their warehouses filled with the materials are located inside the shops. the implication of this system of business which is generally practiced by both small and medium size business involves long business hour stay time with these materials. hence, the exposure scenario is of concern given that these materials have element of natural radioactive materials with their accompanying nuclear particle emissions. of greater concern is the confine space and poor ventilation that characterized most of these shops and this may lead to high radioactive build up especially radon gas concentration. the different shops housing different brands of building materials sold at rwangpam street and building materials market bukuru were covered in the measurement. the instrument use to perform the environmental radiation survey is a gamma scout. the gamma scout is a general purpose survey meter that measures alpha, beta, gamma and x-ray radiation. it has proven to be useful in medical, nuclear, mining, metal scrap and laundry industries. the gamma scout sets a new standard in portable geiger counter performances and functionality. the gamma scout is calibrated across a wide scale (0.01 up to 1000.00 µsv/hr). measurement at each shop/store was performed by holding the gamma-scout at 1m above to ground surface. each measurement was taken three times and the average taken to represent the value for the shops/stores. 3. results and discussion the results are as presented in tables 1 and 2. exposure of persons due to the presence of these building materials in each shops was assessed assuming that exposure was uniformly distributed through-out the year based on 12 hours a day, 6 days a week and 52 weeks in a year for salesmen/saleswoman and shopkeepers that stay at their sales point from morning to evening and for six days in a week. this is the typical daily routine peculiar to the traders at the market. the range and mean values of the indoor and outdoor gamma dose exposure dose rate levels at the various shops are presented in table1, while the annual effective dose values are presented in table 2. the background values in table 1 indicates that the environment dose rate outside the building of the shop while the outdoor values are the dose values where the building materials are usually displayed for sales to prospective buyers. from tables 1 and 2 it could be seen that the indoor doors rates were higher than the outdoor and background values. this is a clear indication of the radiation dose contribution due to these building materials that are always in close proximity with the store keeper in their shops. as could be seen from the table 2, the floor tiles and wall tile shops exhibit higher dose rate compared to other types of shops. the average total annual effective doses due to outdoor and indoor gamma exposures were 1.80msv (floor tiles) and 1.64msv (wall tiles) while for wash hand basin it was 1.69msv, white cement and pvc pipes materials recorded the lowest annual effective dose amongst all the others, these values were obtained as a result of summation of the annual mean indoor gamma dose level with the annual mean outdoor gamma dose level. increase in effective dose in tiles and wash hand basin could be associated with the presence of tenorm in ceramics and the sources of the clay origin. the jos plateau is thought to be an area of young granite which intruded through an area of older granites rock, making up the surrounding state [12]. the presence of the younger granites could also be a factor leading to the increase in the effective dose; the volcanic activities of over 50 million years ago and tin mining activities that took place before and after the colonial era could also increase the exposure level to workers and other individuals of concern. therefore the scare of tin mining is still evident in plateau state and tin city of jos, because the state is dotted with over 4000 abandoned mining ponds, describe as very dangerous as they contained radioactive materials. control on the radioactivity of building materials can be based on dose criteria for controls and on exemption levels. the dose criteria used for control should be defined as the excess exposure caused by building materials, that is the background dose from natural radionuclides in the local typical environment need to be subtracted for the external gamma radiation, the local typical environment can be defined either as the average dose received outdoor, or as the average dose received in a house built from materials with typical activities.. with a median exposure level of 0.52msv arising from building materials at rwang pam street market and building materials market bukuru, a dose criterion of 0.82msv may be considered that will not cause economically and socially intolerable situations on the market. when gamma doses are limited to levels below 1msv/yr. it is recommended that control could be based on a lower dose criterion if it is considered that this is desirable and will not lead to impractical control. it is therefore recommended that controls should be based on doses in the range of 0.3 –1msv/yr. this is the excess gamma dose asian review of environmental and earth sciences, 2014, 1(1): 5-7 7 to that received outdoors. building materials should be exempted from all restrictions concerning their radioactivity if the excess gamma radiation originating from them increases the annual effective dose of a member of the public by 0.3msv [13]. this is the excess gamma dose to that received outdoors. it therefore follow that salesmen and shopkeepers at the major markets in rwang-pam street and building materials bukuru, should spend less time, say, about 10 hours or less a day for 6 days in a week throughout 50 weeks in a year, in order to limit their levels of exposure. 4. conclusion the radiation dose levels in some selected building materials in jos have determined using the gamma scout. the average effective dose annually received by the shop keepers due to building materials varies from (0.621 – 1.818) msv. this suggests that some of the building materials in these shops may not have any significant radiation effect on the shop keepers while some may have some radiation effects on the shop owners. references [1] r. mustonen, "methods for evaluation of radiation from building materials," radiat. prot. dosim., vol. 1, pp. 235 -238, 1985. [2] icrp, production of the public in situations of prolonged radiation exposure: publication 82 elsevier science b.v., 1999. [3] e. stranden, "assessment of the radiological impact by fly ash in cement," health phys., vol. 45, p. 145, 1983. [4] j. somlai, "radiological aspects of the usability of red mud as building material additive," journal of hazardous materials, vol. 150, p. 541, 2008. [5] unscear, "united nations scientific on the effects of atomic radiation. sources, effects and risks of ionizing radiation," report is the general assembly in the annex b. natural sources of radiation. united nations, new york 1977. [6] c. j. chen and y. m. lin, "assessment of building materials from compliance with regulations of roc," environ. internat., vol. 22, pp. s221 – s 226, 1996. [7] s. y. u. stoulos, m. manolopoulou, and c. papastefanou, "assessment of natural radiation exposure and radon exhalation in building materials in greece," j. envrion. radioact., vol. 69, pp. 225-240, 2003. [8] s. righi and l. bruzzi, "natural radioactivity and radon exhalation in building materials used in italian dwellings," j. environ. radioact., vol. 88, pp. 158-170, 2006. [9] f. o. brigido, e. a. montalvan, s. r. rosa, z. j. tomas, and p. a. hemandez, "natural radio nuclides content in building materials and gamma dose rate in dwellings in cuba," j. environ radioact., vol. 99, pp. 1834 -1 1837, 2008. [10] n. k. ahmed, "measurement of natural radioactivity in building materials in qena city, upper egypt," environ radiact., vol. 83, pp. 91-99, 2005. [11] unscear, united nations scientific on the effects of atomic radiations. sources, and effects of ionizing radiation. united nations, new york, 1977; 1993; 2000. [12] d. i. jwanbot, measurement of radioactivity levels in soil and food crop samples in mining areas on the jos-plateau. nigeria: lap lambert publishing house germany, 2012. [13] n. n. jibiri and s. t. u. obarhua, "indoor and outdoor gamma dose rate exposure levels in major commercial building material distribution outlets and their radiological implication and occupant in ibadan, nigeria," journal of natural sciences research, vol. 3, pp. 25-31, 2013. table-1. the range of indoor and outdoor gamma dose rate level at the shops and background dose rate level s/n types of building material indoor (µsv/h) outdoor (µsv/h) background (µsv/h) range mean +sd range mean +sd 1. floor tiles 0.234-0.226 0.23 + 0.01 0.215-0.206 0.21+0.01 0.127 2. wall tiles 0.258-0.264 0.261+0.01 0.226-0.218 0.222+0.01 0.101 3. wash hand basin 0.262-0.226 0.244+0.01 0.224-0.216 0.220+0.01 0.108 4. cements 0.226-0.290 0.258+0.01 0.106 5. white cement 0.290-0.255 0.272+0.01 0.220-0.206 0.213+0.01 0.108 6. paints 0.266-0.226 0.246+0.01 0.214-0.206 0.210+0.01 0.110 7. pvc ceiling 0.226-0.250 0.238+0.01 0.222-0.214 0.218+0.01 0.105 8. pvc pipes 0.268-0.226 0.247+0.01 0.248-0.276 0.260+0.01 0.136 9. iron rods 0.246-0.257 0.251+0.01 0.137 table-2. annual indoor and outdoor effective gamma dose level s/n building materials indoor dose (msv) outdoor (msv) 1 floor tiles 0.977 ± 0.09 0.831±0.01 2 wall tiles 0.924 ± 0.04 0.823 ± 0.05 3 wash hand basin 0.913± 0.03 0.786 ± 0.04 4 cement no items displayed 0.816± 0.04 5 white cement 0.804 ± 0.07 0.775 ± 0.01 6 paints 0.846 ± 0.03 0.876 ± 0.01 7 pvc ceiling 0.827± 0.05 0.793 ± 0.01 8 pvc pipes 0.808 ± 0.01 0.778± 0.03 9 iron rods no items displayed 0.621 ± 0.01 views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn(e) : 2313-8173 issn(p) : 2518-0134 vol. 4, no. 1, 1-6, 2017 http://www.asianonlinejournals.com/index.php/arees 1 analysis of groundwater on wetland area in kapuas regency, central kalimantan indonesia deasy arisanty1  sidharta adyatma2 ellyn normelani3 apriyanto4 ( corresponding author) 1,2,3,4 geography education department, lambung mangkurat university, banjarmasin indonesia abstract southern part of kalimantan is wetland area that included the groundwater basin of palangkarayabanjarmasin. the assessment of the potential of ground water in wells includes the quantity of water use on artesian wells, the physical quality of artesian well water and the groundwater uses. the method used in this study is a survey method with the number of wells drilled studied is 17 wells and 46 wells users. analysis of the data is the percentage obtained from questionnaires distributed to the artesian well. field measurements obtain the water quality data artesian well. the results showed that the quantity of water is good quantity. the water in wells is never dry despite the dry season. artesian well water quality is not good for consumption. based on interviews with residents and the results of field measurements, water color will be red when boiled, so that the water is only used for washing and bathing. keywords: groundwater, wells, wetlands. contents 1. introduction ........................................................................................................................................................................... 2 2. research methods .................................................................................................................................................................. 2 3. results and discussion ........................................................................................................................................................... 2 4. conclusion .............................................................................................................................................................................. 5 references .................................................................................................................................................................................. 5 citation | deasy arisanty; sidharta adyatma; ellyn normelani; apriyanto (2017). analysis of groundwater on wetland area in kapuas regency, central kalimantan indonesia. asian review of environmental and earth sciences, 4(1): 1-6. doi: 10.20448/journal.506.2017.41.1.6 issn(e) : 2313-8173 issn(p) : 2518-0134 licensed: contribution/acknowledgement: this work is licensed under a creative commons attribution 3.0 license all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. history: received: 31 january 2017/ revised: 7 march 2017/ accepted: 9 march 2017/ published: 10 march 2017 ethical: this study follows all ethical practices during writing. publisher: asian online journal publishing group http://creativecommons.org/licenses/by/3.0/ http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2017.41.1.6 https://orcid.org/orcid-search/quick-search?searchquery=deasy arisanty https://orcid.org/orcid-search/quick-search?searchquery=sidharta adyatma https://orcid.org/orcid-search/quick-search?searchquery=ellyn normelani https://orcid.org/orcid-search/quick-search?searchquery=apriyanto http://search.crossref.org/?q=10.20448/journal.506.2017.41.1.6 asian review of environmental and earth sciences, 2017, 4(1): 1-6 2 1. introduction development increasing has the effect for the high of water consumers. water supply source is from surface water, but in some areas, surface water supply is often insufficient. hence, the other source such as groundwater needs to be inventoried [1]. potential of groundwater always refers to the quantity of the groundwater availability and quality of groundwater [2]. good quantity and good quality of groundwater is used for community needs. community needs consists of domestic uses, i.e. for drinking and non-domestic uses, i.e. for agriculture. the domestic and non-domestic uses have impact for water quantity and quality [3]. wetland is the high of potential waters but the human intervention may have effect for the waters quantity and quality. the decreases of wetland area may decreases amount of waters in wetland areas [4, 5]. the effect of human activity for water in wetland area are high urbanization, high population, mining and oil activity, industrial activity, illegal logging, overgrazing, transportation, uncontrolled agricultural, uncontrolled land reclamation. the natural effects for wetland area are subsidence, saltwater intrusion, sand storm, desertification and droughts, invasion of alien flora and fauna [5]. kuala kapuas regency is part of groundwater basin of banjarmasin-palangkaraya. the basin is wetland area. the spread of the water basin covers an area of ± 95,980 km 2 . the major aquifer lithology of basin is alluvium sediment beaches, rivers and wetlands such as gravel, gravel, and sand with graduation medium-high, and less coherent sedimentary rock composed of quartz sandstones and conglomerates, with high graduation. precipitation in the basin has ranges between 2,000-2,500 mm/year. groundwater potential in the shallow aquifer (non-distressed) is about ± 32,393 x 10 m³/year [6]. potential groundwater in the basin is very high. groundwater resources can be utilized as a source of clean water in groundwater basin of banjarmasin-palangkaraya. the higher of population growth in the region, the higher also need water for daily use [6]. the objectives of research are to analyze the quantity of groundwater in artesian well of kapuas regency, to analyze the quality of groundwater in artesian well of kapuas regency, to analyze groundwater uses in kapuas regency. 2. research methods the research location is wetland area in groundwater basin of banjarmasin-palangkaraya. groundwater is taken through artesian well, which the artesian well are spread throughout the basin. the number of samples is 17 of wellbore. respondents from user of artesian well are 43 people. data are obtained through a questionnaire to identify the quantity of groundwater (the amount of ground water in the artesian well, the material, the depth of the wells, drought artesian well, material in the artesian well, the quality of drilled wells, and the type of use of the artesian well). field measurements collects the physical quality of groundwater which includes the taste of water, the color of water, the smell of the water, temperature, electrical conductivity (ec), the content of nacl, and tds. the location of research is presented in figure 1. figure-1. location of research source: administration map of kapuas district (2016) 3. results and discussion a. potential of groundwater in artesian well in research area 1. quantity of groundwater a. the quantity of ground water in the artesian well the quantity of groundwater is determined by the amount of available of groundwater during the wet season and dry season. more of water taken in the artesian well indicates that groundwater has large quantities. groundwater in artesian wells in the wet season and dry season is presented in table 1 and figure 1. asian review of environmental and earth sciences, 2017, 4(1): 1-6 3 table-1. the quantity of groundwater uses in wet season and dry season criteria wet season dry season f % f % 40-60 liter 40 93.02 4 9.30 60-80 liter 1 2.33 3 6.98 80-100 liter 2 4.65 2 4.65 > 100 liter 0 0.00 34 79.07 total 43 100 43 100 source: primary data analysis (2016) figure-2. the quantity of groundwater uses in wet season and dry season source: primary data analysis (2016) artesian well is used by the people, especially in the dry season due to people use water from other sources in wet season, example from rainwater and rivers. water wells uses approximately 79.07% of people. this indicates that the water wells have a good potential to serve as a source of clean water for daily needs, especially in the dry season. b. the depth of the artesian well artesian well in swamp area is a relatively deep well to obtain the high groundwater quantity and good quality. the depth of wells drilled in the study area is presented in table 2 and figure 2. table-2. the depth of the artesian well criteria frequency (f) percentage (%) < 50 meter 2 4.65 50-75 meter 1 2.33 75-100 meter 5 11.63 > 100 meter 35 81.40 total 43 100 source: primary data analysis (2016) wells in the study area is a deep well, since 81.4% has a depth of > 100 meters. it is intended to get water in large quantities and a better quality. the shallow wells have a risk of drought and low of ph. c. drought in artesian wells drought in artesian well may occur in the dry season. drought of artesian well is presented in table 3. table-3. the artesian wells drought criteria frequency (f) percentage (%) never 40 93.02 sometimes 2 4.65 often 1 2.33 always 0 0.00 total 43 100 source: primary data analysis (2016) the data in table 3 indicates that drought never occurred in wells. about 93.02% of the respondents claimed that drought never occurs in the rainy season and the dry season. this indicates that the wells in the wetland of kapuas regency has good potential due to water is always available in the wet season and the dry season. d. materials of groundwater material of well determine the quantity of groundwater. groundwater with the sand material has the good aquifer. material on the wells is presented in table 4. asian review of environmental and earth sciences, 2017, 4(1): 1-6 4 table-4. material of wells artesian criteria frequency (f) percentage (%) sand and gravel 10 23.26 fine sand 32 74.42 clay 1 2.33 rock 0 0.00 total 43 100.00 source: primary data analysis (2016) the data in table 4 illustrates that the material in the wells is dominated by fine sand (74.42%). sand and gravel has the percentage about 23.26 %.the groundwater in the study area included in the aquifer. it means the groundwater has a good potential. there are approximately 2.33% of wells has a clay material. this means that the wells artesian have the low potential. the wellbore is possible to dry, especially during the dry season. 2. groundwater quality result of ground water measurement is presented in table 5. table-5. groundwater quality no sub district village water flavor temperature ( o c) dhl (µs) nacl (%) tds ppm color water smell 1 selat selat dalam tasteless 29.4 578 1.50 287 clear smell of mud 2 selat selat dalam tasteless 29.4 577 1.50 286 clear smell of mud 3 selat selat dalam tasteless 29.4 578 1.50 287 clear smell of mud 4 selat selat dalam tasteless 29.3 578 1.50 287 clear smell of mud 5 selat selat dalam tasteless 29.4 578 1.50 286 clear smell of mud 6 selat selat dalam tasteless 29.3 577 1.50 286 clear smell of mud 7 selat selat utara tasteless 31.8 349 1.10 174 clear odorless 8 selat selat utara tasteless 31.3 350 1.20 173 clear odorless 9 selat selat utara tasteless 31.7 350 1.10 173 clear odorless 10 selat selat utara tasteless 31.8 348 1.10 174 clear odorless 11 selat selat tengah tasteless 31.6 752 1.90 375 clear odorless 12 selat selat barat tasteless 31.6 536 1.40 262 clear odorless 13 selat selat hilir tasteless 30 561 1.40 279 clear odorless 14 selat selat hilir tasteless 30 560 1.40 278 clear odorless 15 selat selat hilir tasteless 30.5 560 1.40 278 clear odorless 16 selat selat hilir tasteless 30.2 562 1.40 279 clear odorless 17 selat selat barat tasteless 31.7 753 1.90 376 clear odorless source: primary data analysis (2016) table 5 illustrates the quality of artesian well water of about 17 boreholes have been measured physical quality. in terms of taste, water wellbore has the tasteless with the temperatures ranging between 31.8-29.3 °c. electrical conductivity is low, it means that the water is fresh water due to the dhl value is an approximately 300-500 μs. nacl content is about 1.2-1.9% nacl or low of nacl. tds value or the amount of sediment dissolved is ranging from 100-300 ppm, which means including a lower category. wellbore water is also in clear conditions but some of the wellbore has mud smell. in general, wellbore waters in the study area in terms of the physical qualities are eligible to be used for everyday purposes. table-6. physical quality of ground water in the wellbore based on user perception criteria water smell water color water turbidity frequency (f) percentage (%) frequency (f) percentage (%) frequency (f) percentage (%) never 23 53.49 36 83.72 36 83.72 rarely 16 37.21 5 11.63 4 9.30 often 2 4.65 2 4.65 2 4.65 always 2 4.65 0 0.00 1 2.33 total 43 100 43 100 43 100 source: primary data analysis (2016) based on the analysis in table 6 most users stated that the wellbore are never odorless, colorless, and not cloudy. thus, the people stated that in terms of physical quality, wellbore water in research area is classified as good of physical quality. b. the uses of groundwater the use of groundwater in wellbore in research area is presented in table 7. based on data in table 7 the most of the water in the wellbore is used for household needs such as for drinking, sanitation, bathing and washing. this is consistent with the objective of making the wellbore to satisfy the needs of clean water in the wetland area. the non-domestic uses of wells waters are for mosque and schools. table 8 explains that the most people do not use artesian well water for drinking and cooking. according to them, if the water is heated, the water color will change to red indicating the iron content in the water is high enough. this causes people to worry poisoning when consumed the water from an artesian well. the water is used for sanitation, bathing, and washing. thus, although the potential is high artesian well water but the water cannot be used for drinking water sources. people still have to look for other water sources, for example from rainwater or bottled asian review of environmental and earth sciences, 2017, 4(1): 1-6 5 water factory with a better quality than the water in the wellbore. nevertheless, the presence of artesian well water helps the community to meet the needs of water for sanitation, bathing and washing, especially during the dry season. table-7. the use of groundwater in the wellbore no sub district village groundwater uses 1 selat selat dalam domestic 2 selat selat dalam domestic 3 selat selat dalam domestic 4 selat selat dalam domestic 5 selat selat dalam domestic 6 selat selat dalam domestic 7 selat selat utara domestic 8 selat selat utara domestic 9 selat selat utara non domestic 10 selat selat utara non domestic 11 selat selat tengah domestic 12 selat selat barat domestic 13 selat selat hilir domestic 14 selat selat hilir domestic 15 selat selat hilir domestic 16 selat selat hilir non domestic 17 selat selat barat domestic source: primary data analysis (2016) tabel-8. groundwater uses criteria drinking cooking sanitation bathing washing f % f % f % f % f % always 0 0.00 1 2.33 12 27.91 23 53.49 24 55.81 often 1 2.33 3 6.98 22 51.16 14 32.56 19 44.19 rarely 3 6.98 4 9.30 6 13.95 2 4.65 0 0.00 never 39 90.70 35 81.40 3 6.98 4 9.30 0 0.00 total 43 100 43 100 43 100 43 100 43 100 source: primary data analysis (2016) groundwater contained in wetland area of banjarmasin palangkaraya have high potential due to the wells is never drought despite in the dry season. water is also categorized as a good aquifer because of the sand material. people use the groundwater in large quantities, especially in the dry season. wellbore has been the source of water used by the public, especially in the dry season. physical quality of groundwater in research area is tasteless, colorless, tasteless, low salt content, and low sediment dissolved which indicates that the physical quality of water is good. groundwater is contained in the wellbore has been used by people for their daily needs, especially for sanitation, washing and bathing. people do not use artesian well water for cooking or drinking because the water will be changed to red when heated. community use rainwater or bottled water for drinking and cooking. wetland groundwater has the high of dissolved organic carbon due to the groundwater flows through the high of organic sediment [7]. the flood flows through groundwater has effect for characteristic of groundwater and surface water on wetland [8]. surface water flows in wetland, then groundwater rises stagnant [9]. arisanty [10] stated that the basin of banjarmasin-palangkaraya, especially in barito delta has the material consist of sand, clay, and sand and brackish water. sand layer has the thickness about 7 m, clay has the thickness about 36-65 m sand and brackish water has the thickness about 29 m. the thickness of sand material indicates that the basin has the high potential of groundwater but the organic material and brackish water decreases the quality of groundwater. 4. conclusion the quantity of groundwater in wellbore is good because the wells never drought despite in the dry season. generally, physical quality of water wells is good quality, but there are few boreholes smelling mud that indicates a less good quality. wellbore water is used for sanitation, bathing and washing. water is not used for drinking and cooking because of their reddish color when water is heated. references [1] m. j. erwinta, w. matondang, w. sumartiani, and h. simanjuntak, "hydrogeological mapping scale of 1: 50,000 in kapuas, central kalimantan province," research report, ministry of mines and energy of the central kalimantan province, bandung, 1996. [2] r. s. hidayat, "groundwater potential of groundwater basin in sambas, kalimantan barat province," jurnal geologi indonesia, vol. 3, pp. 205-212, 2008. [3] s. singh, n. j. raju, and c. ramakrishna, "evaluation of groundwater quality and its suitability for domestic and irrigation use in parts of the chandauli-varanasi region,uttar pradesh, india," journal of water resource and protection, vol. 7, pp. 482-497, 2015. view at google scholar | view at publisher [4] k. p. nyarugwe, "effect of surface water management measures on a groundwater fed wetland," thesis, the faculty of geoinformation science and earth observation of the university of twente, 2016. [5] h. o. nwankwoala, "case studies on coastal wetlands and water resources in nigeria," european journal of sustainable development, vol. 1, pp. 113-126, 2012. view at google scholar [6] sihwanto and wahyudin, "groundwater conservation of palangkaraya-banjarmasin basin and pagatan basin, south kalimantan basin pagatan," research report, ministry of mines and energy of the central kalimantan province, bandung, 2005. https://scholar.google.com/scholar?hl=en&q=evaluation%20of%20groundwater%20quality%20and%20its%20suitability%20for%20domestic%20and%20irrigation%20use%20in%20parts%20of%20the%20chandauli-varanasi%20region,uttar%20pradesh,%20india http://dx.doi.org/10.4236/jwarp.2015.77046 https://scholar.google.com/scholar?hl=en&q=case%20studies%20on%20coastal%20wetlands%20and%20water%20resources%20in%20nigeria asian review of environmental and earth sciences, 2017, 4(1): 1-6 6 [7] j. f. elder, n. b. rybicki, v. carter, and v. weintraub, "sources and yields of dissolved carbon in northern wisconsin stream catchments with differing amounts of peatland," wetlands, vol. 20, pp. 113-125, 2000. view at google scholar | view at publisher [8] t. s. mccarthy, "groundwater in the wetlands of the okavango delta, botswana, and its contribution to the structure and function of the ecosystem," journal of hydrology, vol. 320, pp. 264-282, 2006. view at google scholar | view at publisher [9] p. schot and t. winter, "groundwater–surface water interactions in wetlands for integrated water resources management," preface, journal of hydrology, vol. 320, pp. 261–263, 2006. view at google scholar | view at publisher [10] arisanty, morphodynamic of barito delta, southern kalimantan. dissertation, faculty of geography. yogyakarta, indonesia: gadjah mada university, 2013. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=sources%20and%20yields%20of%20dissolved%20carbon%20in%20northern%20wisconsin%20stream%20catchments%20with%20differing%20amounts%20of%20peatland http://dx.doi.org/10.1672/0277-5212(2000)020%5b0113:sayodc%5d2.0.co;2 https://scholar.google.com/scholar?hl=en&q=groundwater%20in%20the%20wetlands%20of%20the%20okavango%20delta,%20botswana,%20and%20its%20contribution%20to%20the%20structure%20and%20function%20of%20the%20ecosystem http://dx.doi.org/10.1016/j.jhydrol.2005.07.045 https://scholar.google.com/scholar?hl=en&q=groundwater–surface%20water%20interactions%20in%20wetlands%20for%20integrated%20water%20resources%20management http://dx.doi.org/10.1016/j.jhydrol.2005.07.021 asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 2, 39-42, 2014 http://www.asianonlinejournals.com/index.php/arees 39 physico-chemical and microbial assessmentof some well water from mista-ali town, bassa lga, plateau statenigeria kangpe, n.s. 1 --egga, e.s. 2 -- mafuyai, g.m. 3 1,2,3 department of pure and industrial chemistry, university of jos, jos. nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction water is very essential to the survival of all organisms and the human body is composed of approximately 70% water by mass [1].safe drinking water is a human birthright as much a birthright as clean air. an adequate supply of safe and portable water assist in preventing the spread of gastrointestinal diseases, supports domestic and personal hygiene and improves the standard of living. however, much of the world’s population does not have access to safe drinking water. lack of portable water threatens the economy of a nation and the people’s health in different ways, which is true of the nigeria case that oil spillage kills all aquatic life form and leaves the people without good drinking water in some villages of the niger-delta region of the country, also indiscriminate dumping of refuse and other wastes into ponds, rivers, lakes and other water bodies in the south west [2]. the most important and life sustaining human drink is hardly found 100% pure in nature due to human activities and other natural factors. many diseases in developing countries are caused by drinking contaminated water [3] and ibe, et al. [4]. this is because dead vegetation, metal leachates from solid waste dumps; leaching of rocks, sewage, industrial wastes and agricultural chemicals return eventually to the river by run offs [5].the quality and quantity of water are affected by an increase in anthropogenic activities and any pollution either chemical or physical causes changes to the quality of the recurring water body [6]. as population increases, the need of water for domestic, transport, power, agricultural and industrial purposes also increases. government has been the major supplier of portable water for its populace in nigeria. with the way population is increasing at a very fast rate and subsequent expansion in settlement, government finds it difficult to satisfy the water need of its citizens. this results in individuals and communities depending on other sources of water such as rivers, streams, boreholes and well. apart from expansion as a result of increase in population, other reason such as crises has led to the development of settlement towns in nigeria. these private water sources are not subjected to any quality standard before usage by the residents thereby resulting in the consumption of contaminated water. jos the capital city of plateau state, nigeria has had ethno-religious crises for the past decade which has resulted in the development of new settlements outside the state capital in which mista-ali is one of such towns. although an the physico-chemical and microbial assessment of well water in mista-ali were carried out to determine its suitability for domestic consumption. samples were collected from eight wells in duplicate and analyzed using standard methods. the results revealed the physical parameters of the well water as colourless, odourless, tasteless, with total solids (240-370mg/l), total suspended solids (280-320 mg/l) and total dissolved solids (195-240mg/l). the chemical `parameter showed that the well has ph(6.97.3) conductivity (2.0x10 2 -7.0x10 2 µmhos/cm), alkalinity(12-28mg/l),chloride (10-28 mg/l), total hardness (180-320mg/l), sulphate (280-300mg/l), and nitrate (7.70-8.20mg/l) . arsenic and zinc were not detected while the following metals were detected with the following concentrations pb (0.0030.005), fe (0.120-0.890),mn (0.002-0.029), ca (20.00-220.00), cu (0.002-0.006), cu (0.002-0.006), cr (0.001-0.008), ni (0.004-0.011), k (2.24-9.84), mg (15.60-18.80). the physical, chemical and microbial assessment results were within the permissible standard for portable water. the well water in mista-ali can be used for domestic purposes and recommended that the water be analyzed atleast once every year to check for contamination. there should also be state agency that would license well water to maintain high hygienic conditions. keywords: well water, physico-chemical assessment, microbial assessment, trace metals, contamination, nigeria. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(2): 39-42 40 old tin mine village, it has metamorphosed into a settlement with a population of over fifty thousand inhabitants. most residents do not have access to pipe borne or borehole water and have resorted to the use of stagnant water in the old tin mine ponds and hand dug wells as sources of water for their domestic consumption/usage. in this study, the work aimed at examining the water quality and microbial characteristics of wells that serve as the main source of portable water for the inhabitants/residents of mista ali, a settlement close to jos metropolis. 2. materials/methods the samples containers (one litre plastic container with a screw cap) were washed properly with detergent, leached with conc. hno3, rinsed with distilled water until acid free and finally with the water source. water samples were collected from eight different wells into the prepared containers manually. the containers were labeled with masking tape containing sample number, date and time and kept in the laboratory refrigerator at 4 o c prior to analysis. samples for heavy metals analysis were preserved by adding 3 drops of conc. hno3.the water samples for bacteriological analysis were collected in sterilized neutral glass bottles of 120ml capacity with stoppers and kept in the refrigerator pending analysis. colour, odour and taste were analysed with sense organs. the temperature of the water sample at point of collection was determined using a mercury in glass thermometer (british standard, bs 593) while the ph was determined using a philips model pw 9418 ph meter after the meter had been dully calibrated with standard buffers of ph 4.0, 7.0 and 9.0 [7]. conductivity was determined using the bridge type m.c 3 conductivity meter calibrated in limbos. alkalinity, total hardness, and chlorides were determined by titrimetric method. total solids and total dissolved solids were determined by gravimetric technique.sulphates were done by turbidimetric technique while metallic elements including heavy metals were analyzed using atomic absorption spectroscopy model vgb 210 system. microbial analysis were carried out by pour plating method using serial dilution technique [8]. 3. results table-1.results of the physical parameters of well waters in mista ali town. parameters 1 2 sample 3 numbers 4 5 6 7 8 temperature ( o c) 28.00 27.90 28.10 27.80 28.10 28.40 27.80 28.00 color colorless colourless colourless colourless colourless colourless colourless colourless odor odorless odorless odorless odorless odorless odorless odorless odorless taste unobj unobj unobj unobj unobj unobj unobj unobj ts(mg/l) 240 290 370 255 260 300 310 300 tss(mg/l) 320 220 300 310 315 280 275 300 tds (mg/l) 215 200 220 195 210 210 240 210 tss-total suspended solids, ts-total solids, tds-total dissolved solids, unobj-unobjectionable table-2. chemical parameters of well waters in mista ali town. parameters 1 2 sample 3 number 4 5 6 7 8 conductivity (µmhos/cm) 2.0x10 2 4.0x10 2 8.0x10 2 5.0x10 2 4.0x10 2 6.0x10 2 7.0x10 2 6.0x10 2 alkalinity (mg/l) 28.00 16.00 16.00 12.00 24.00 20.00 18.00 23.00 chlorides (mg/l) 12.00 28.00 12.00 16.00 16.00 12.00 10.00 18.00 total hardness (mg/l) 270.00 280.00 252.00 280.00 140.00 180.00 300.00 320.00 sulphate (mg/l) 300.00 320.00 280.00 200.00 300.00 290.00 300.00 310.00 nitrate (mg/l) 8.00 7.80 8.00 7.60 6.00 8.20 8.00 7.70 ph 7.0 7.2 6.9 7.3 7.2 7.3 7.2 7.0 table-3. metal content concentration (mg/l) of the well waters in mista ali parameters 1 2 sample 3 number 4 5 6 7 8 zn nd nd nd nd nd nd nd nd pb 0.005 0.005 0.004 0.004 0.005 0.003 0.003 0.004 fe 0.890 0.180 0.780 0.326 0.430 0.120 0.180 0.170 mn 0.029 0.025 0.011 0.012 0.016 0.001 0.002 0.020 ca 220.00 20.00 40.00 100.00 120.00 100.00 130.00 80.00 cu 0.002 0.004 0.004 0.002 0.003 0.005 0.006 0.005 cr 0.006 0.008 0.002 0.001 0.004 0.003 0.002 0.002 ni 0.008 0.004 0.007 0.008 0.011 0.006 0.007 0.008 k 2.240 3.170 9.840 5.470 6.200 5.300 6.000 5.400 mg 18.400 17.000 16.600 15.600 12.700 18.000 12.000 18.800 as nd nd nd nd nd nd nd nd asian review of environmental and earth sciences, 2014, 1(2): 39-42 41 table-4. microbiological analysis of well waters of mista ali sample number mpn/100ml/l of total coliform 1 50.30 2 57.20 3 26.00 4 24.00 5 55.00 6 56.00 7 31.00 8 80.00 4. discussion table 1 presents the physical parameters of the sampled well waters. the results show that the temperature ranged between 27.80 and 28.00 0 c. temperature is one of the most important parameters for aquatic environment because all the physical, chemical and biochemical properties are governed by it [9]. all the values are lower than the ones reported by amoo and akinbode [10] for well waters in minna and environs but close to the values reported for shallow wells near dump sites in akure [11]. although there is a seasonal fluctuation in well water temperature values, this may be due to function of the climatic condition at a particular geographical location and period. the sampled water are colourless, odourless and has unobjectionable taste which makes the water aesthetically acceptable [8]. the values of the ts, tss and tds ranged between 240-370, 220-315 and 195-240mg/l respectively. these values are all below the son [12] and who [13] maximum values of 500 and 600mg/l and similar to the ones reported by ezeribe, et al. [14] for well water samples in kaltungo, dass and langtang north. the chemical parameters are shown in table 2 for the sampled well waters. the conductivity ranged between 2.0x10 2 and 8.0x10 2 µmhos/cm. these values are below the highest permissible values recommended by son [12] of 900µmhos/cm and who [13] 1000µmhos/cm. these values are higher than the values reported by ezeribe et al for dass, kaltungo and langtang. the difference may be due to difference in geochemical conditions and soluble ions in the locations analysed. the total alkalinity of the samples which ranged between 12.00 and 28.00mg/l are below the maximum desirable level of 100mg/l for drinking water. the low values of alkalinity indicate absence or low amount of carbonates and bicarbonates in the well waters which contributes to the hardness of the water. the values of the chloride in the sampled waters also fall within the 100mg/l recommended for drinking water. chlorides results from the leaching of chloride containing rocks and soils with which the water comes in contact. also chlorides are the most stable components in water and its concentration is largely unaffected by most natural physico-chemical and biochemical processes, hence its value in water is a useful measure in water sample. the total hardness and sulphate values of 140-300mg/l and 200-310mg/l shows that the sampled well waters were fairly soft, being within who limits of 400 and 500mg/l respectively. this further explains the absence or low amount of carbonates and bicarbonates that may cause poor lather formation and scales in boilers. the nitrate content of all the well waters 10.00-18.00mg/l is within the son permissible limits of 100mg/l. nitrates indicates the presence of oxidized organic matter. excess nitrates cause methemoglobin as blue baby disease and also indicates presence of other serious residential or agricultural contaminants such as bacteria, fertilizers and pesticides [15]. the ph values range of 6.9 -7.3 are within the permissible level recommended by who of 6.5-7.85.it is in agreement with what was reported in other researches in similar studies. low ph values causes corrosion which can lead to leaching of household common metals and increase the toxic and fowl smelling hydrogen sulphide [10]. table 3 shows the level of pb, fe, mn, ca, cu, cr, ni, k and mg in the sampled well waters. pb concentration of (0.003-0.005mg/l) shows that the sampled waters are not exposed to indiscriminate disposal of lead battery. lead even at low concentration is known to be toxic and has no known function in biochemical process. it can impair the nervous system and affect foetus, infants and children resulting in lowering of intelligent quotient even at its lowest dose [16]. fe concentration of (0.120-0.590 mg/l) is within the permissible level of son and who, high concentration could give rise to iron-dependent bacteria which in turn can cause further deterioration in the quality of water through the development of slimes and unobjectionable odour. also high concentration of iron could causes haemasiderosis. mn concentration of (0.011-0.029 mg/l) is within the who and son permissible level, this could also be because of no direct contact with pipes and taps. it is an essential element and has a moderate toxicity. it has being implicated in neurological problems especially when inhaled. calcium concentration is between (20.00-220.00 mg/l) for the wells. copper concentration of (0.02-0.06 mg/l) is within the son and who permissible level. copper is an essential metal and play an important role in enzyme activities [17]. chromium concentration (0.0110.006 mg/l) is within the permissible level. the metal is essential to life and its deficiency results in diabetic mellitus and increase the toxicity of lead [17]. ni (0.004-0011 mg/l), k (2.24-9.80 mg/l) and mg (12.70-18.00 mg/l) were within the permissible level for portable water. zn and as were not detected. the observed trend could be as a result of the geographical location of the wells. the results for the microbial analysis are shown in table 4, which indicates very low coliform counts for all the wells, indicating few presence of coliform.the coliform counts are all below the standard of 3mpn/ml for coliform in drinking water [18]. this can be due to the fact that all the sampled well water were ringed and properly covered preventing entrance of dirts into the well water. 5. conclusion all the water quality parameters examined for well waters in mista-ali town, bassa local government area plateau state revealed that the well water is fairly soft, has low level of trace metals and absence of micro organism that are harmful. it is recommended that the settlers/inhabitants can use their well water for domestic purposes and also advised to carry out analysis on the well water at least once every year because groundwater movement is asian review of environmental and earth sciences, 2014, 1(2): 39-42 42 usually slow, polluted water may go undetected for a long time as most contamination is discovered only after drinking water has been affected and people become ill. government should also involve health workers in giving awareness to inhabitants on use of safe water. references [1] e. d. enger and b. f. smith, environmental chemistry. return press ltd, 2004. [2] j. j. gongden and y. n. lohdip, "climate change and dams drying. a communities case study of three communities in langtang south lgc of plateau state, nigeria," african journal of natural sciences, vol. 12, pp. 37-43. issn: 1119-1104, 2009. [3] a. i. tar, i. s. eneji, s. o. ande, f. o. oketunde, s. r. ande, and r. shaaton, "assessment of arsenic in drinking water in makurdi metropolis of benue state, nigeria," j. chem. soc. nigeria, vol. 34, pp. 56-62, 2009. [4] k. m. ibe, a. h. o. sowa, and o. c. osondu, "environmental contamination and other anthropogenic impacts on otamiri and nworie rivers, owerri, nigeria," jour. of min. geo., vol. 26, pp. 28-29, 2001. [5] f. a. ademola, "baseline heavy metals concentration in river sediments with okikipopo south east belt of the nigerian bituminious sand field," j. of chemical society of nigeria, vol. 33, p. 29, 2008. [6] m. o. aremu, o. olaofe, p. p. ikokoh, and m. m. yakubu, "physicochemical characteristics of streams,well and borehole sources in eggon, nassarawa state, nigeria," j. chem. soc. nigeria, vol. 36, pp. 95-101, 2011. [7] c. m. a. ademorati, standard methods for water and effluent analysis. ibadan: foludex press ltd, 1996. [8] e. h. o. egboh and e. m. emeshilli, "physico-chemical characteristics of river ethiope source in umuaja, delta state,nigeria," j. chem. soc. nigeria, vol. 32, pp. 72-78, 2007. [9] aph, standard methods for examination of water and waste water. american public health association, 12th ed. newyork: boyd printing press company, 1965. [10] i. a. amoo and a. m. akinbode, "physico-chemical analysis of well waters in minna and its environs, niger state nigeria," j. chem. soc. nigeria, vol. 32, pp. 122-127, 2007. [11] k. o. ipinmoroti, "water quality of shallow wells located close to dump sites in akure, nigeria," pak. j. of science and ind. res., vol. 36, pp. 137-142, 1993. [12] son, "standard organization of nigeria safe drinking water regulation," 2003. [13] s. who, "guideline for drinking water quality," geneva world health organization, pp. 19-24, 2003. [14] a. i. ezeribe, k. c. oshieke, and a. jauro, "physico-chemical properties of well water from some villages in nigeria with cases of stained and mottle teeth," science world journal, vol. 7, available www.scienceworldjournal.org, 2012. [15] a. rim-rukeh and irerhievwie, "seasonal variability of nitrate in drinking water resources. in niger delta area, nigeria," j. chem. soc. nigeria, vol. 37, pp. 59-64, 2012. [16] un (united nations), global opportunities for reducing use of lead gasoline. switzerland: iomc/unep/chemicals/98/9, 1998. [17] m. o. aremu, d. u. sangari, b. z. musa, and m. s. chaanda, "assessment of ground water and stream quality for trace metals and physic-chemical contamination in toto lga of nassarawa state, nigeria," int. j. chem. sci., vol. 1, pp. 8-19, 2008. [18] twas, "safe drinking water. the need,the problem, solutions and action plan," third world academic of sciences, italy, pp. 8-12, 2002. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://www.scienceworldjournal.org/ asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 3, 54-60, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 54 aptitude of groundwaters for irrigation in katiola area m.s. oga 1 --f. m. gnamba 2* --b. adiaffi 3 --t. soro 4 --k oulai 5 --j.biemi 6 1,3,4,5,6 department of science and technical water and environmental engineering (destege), félix houphouët-boigny university, côte d’ivoire 2 department of geosciences, pelefero gon coulibaly university, côte d’ivoire abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 55 2. study area and geological setting .......................................................................................................................................... 55 3. methodology .............................................................................................................................................................................. 56 4. results ........................................................................................................................................................................................ 57 5. discussion ................................................................................................................................................................................... 59 6. conclusion .................................................................................................................................................................................. 60 references ...................................................................................................................................................................................... 60 the increasing pressures of agricultural development surfaces on water resources availability of katiola area obliged farmers to the use groundwater for food crops irrigation. however, groundwater used for irrigation makes an impact on soil quality. the aim of this study is to estimate the capability of katiola area ground waters to irrigate food crops by using an approach based on sodium absorption ratio (sar) and permeability index (pi). the results show that most of the groundwater samples (67%) in the study area are suitable for irrigation, except few points located in south-east. keywords: groundwater, soil, irrigation, cultures, katiola, côte d’ivoire. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(3): 54-60 55 1. introduction the area of katiola has been in recent decades a sustained agricultural development attention. food crops such as yams, rice and maize dominate the area. citrus fruits production is important in the south-east quarter, and cotton has taken a fairly important place in the whole area under the leadership of a state company called ivorian company for textile development (cidt). we note an increase in rice production from 2400 to 3000 tonnes from 1980 to 1984. during the 1988 campaign, the number of rice farmers in the region increased to 1467 individuals for a surface area of 1977 ha [1]. the evolution of cotton production in the region is given by figure 1. from 2008-2009 to 20102011 campaigns, the production decreases with respectively 2970.89 and about 1000 tonnes. after 2010-2011 campaign, the cotton production increases during 2011-2012 and 2012-2013 campaigns. it evolves from 1000 to 5708.22 tonnes. therefore, more and more increasing pressures according to development of agricultural production on the water resources availability in the area, obliged farmers to use groundwater for irrigation of crops. in fact, surface water sources dry up often in the dry season and are most vulnerable to climate hazards. governments and farmers have prepared a lot of irrigable spaces in the areas. however, their use has some consequences on soil quality. indeed, the irrigation water requirements depend on the type of plant, soil and chemical water quality [2]. if the water used for irrigation has high concentrations of na + and low of ca 2+ , the exchangeable ion complex may be supersaturated in na + , degrading the structure of the soil, due to the dispersion of clay particles [3]. in addition, salt waters with an electrical conductivity less than 200 μs.cm -1 have a strong trend to mobilize quickly calcium from the soil, which promotes the dispersion of the particles and the clogging of pore spaces [4]. a study of water suitability for irrigation is therefore important. the aim of this work is to study the ability of groundwater in katiola area for irrigation. figure-1. evolution of cotton production in katiola department from 2008 to 2013 2. study area and geological setting the katiola area is located at 434 km of abidjan in the central-north part of côte d'ivoire. it lies between longitudes 4°75 and 5°75 west and latitudes 7°95 and 9°45 north (fig.2). the study area covers 9452 km 2 , with an estimated population of 165 652 inhabitants [5]. the climatic conditions are between sudanese and guinean climate. the area is drained by (bandama and n’zi) two major rivers and their tributaries, which constitute the natural boundaries of the department, the bandama at west and n'zi at east. figure-2. map location of the study area asian review of environmental and earth sciences, 2015, 2(3): 54-60 56 katiola department lies in the baoulé-mossi area with a diversity of birimian rocks, the main ones are: granitoids, metavulcanits, green rocks and metasediments [6]. crystalline rocks are mainly constituted by migmatites and undifferentiated granites, gneisses and tectonic granites overlapping volcano-sedimentary sequences in most part of the katiola department (fig.3). according to hydrogeological point of view, these rocks have a very low porosity and permeability in sound condition. however, tectonic and physico-chemical phenomena that affect the rock induce secondary porosity and permeability, allowing often these formations to become productivity aquifers. we note the presence of three types of aquifers; regolith aquifers, cracks aquifers and fractures aquifers. figure-3. geological map of the study area 3. methodology 3.1. data for the purposes of this study, 82 water boreholes in the study area have been investigated. these waters have been selected to be the sampling network. these data are from a "post-crisis emergency rehabilitation boreholes" program in the northern regions of côte d'ivoire, particularly in katiola area. this project called "fed 9 acp ivc 003 / 030/ 000" comes from the european union (ue) and regional center for water supply and sanitation-côte d’ivoire (crepa–ci) is its prime contractor. the sampling campaign of water samples took place from 09/02/2005 to 06/04/2006. the chemical characterization focused on, the physico-chemical parameters (temperature, ph, salinity, electrical conductivity) measured in the field and the major components analyzed in the laboratory (dry residue , chloride anions cl , sulphate so4 2, bicarbonate hco3 , nitrate no3 and calcium cations ca 2+ , magnesium mg 2+ , sodium na + , potassium k + . the quality of groundwater for irrigation may be assess from several parameters [7]. these parameters are sodium adsorption ratio (sar), total hardness, mg-hazard (mh), sodium percentage (na%), salinity hazard, permeability index (pi) and kelly’s ratio [8]. 3.2. water’s parameters of agricultural use calculation the main factors that can degrade the water quality for irrigation is therefore the concentration of dissolved salts, give as the dry residue or electrical conductivity, potential salinity, the relative concentration of sodium and the amount of toxic elements (boron and chlorine) in water [9]. the total salinity is generally expressed by the total mineralization or electrical conductivity (ec). the latter is related to the dry residue (rs) and the osmotic pressure (π) by formulas 1 and 2: rs (mg.l -1 ) = 0, 7ec (μs.cm -1 ) eq. 1 π (atm.) = 0, 00036*ec eq. 2 soil salinity contains all the chlorides of sodium salts and magnesium sulfates. potential salinity (ps) can be estimated by doneen [10]: ( ) eq. 3 all terms are expressed in milliequivalent per liter (meq/l). the presence of na + has harmful effects on soil structure through deflocculation of clay [9]. these effects are interpreted by different authors by calculating several parameters such as the sodium adsorption ratio (sar), sodium percentage (na %), sodium exchange percentage (esp), etc. asian review of environmental and earth sciences, 2015, 2(3): 54-60 57 the sar parameter evaluates the sodium hazard in relation to calcium and magnesium concentrations. this parameter is commonly used as an index to evaluate water suitability for irrigation purposes [4, 11]. the sar was calculated by the following equation (4): √ eq. 4 if the sar value is less than 10, the water is safe to irrigate with no structural deterioration. the sodium percentage is an important parameter for studying sodium hazard. it is calculated using the following formula [12] and all concentration are expressed in meq/l: eq. 5 the sodium exchange percentage is calculated by using equation 6: eq. 6 a = 0, 0126 and b = 0, 01475 the first three terms have been combined in a single formula (equation 7) called the permeability index (pi) defined by doneen [10]: √ . eq. 7 here, like for the others parameters, all the concentrations are in meq/l. interpretation from diagrams two characteristics diagrams were used to determine the suitability of groundwater for irrigation in katiola area:  the sodium adsorption ratio based on the electrical conductivity containing information on the salinity and the risk of soil alkalinization called also sodium hazard (united states salinity laboratory’s diagram (ussl) [13].  the doneen [10] diagram using the potential salinity, soil permeability index and concentrations of toxic substances in water. 4. results 4.1. physico-chemical parameters analyzes the standard method for assessing the water quality for irrigation highlights two characteristics water: overall saltiness estimated by measuring conductivity, and indicator of the risk of secondary salinization and more or less alkalizing of the ground irrigated, expressed by the value of sar « sodium adsorption ratio » [14]. the results of groundwater samples analysis from katiola area are presented in table 1. these results show that groundwater samples are characterized by low salinity. the electrical conductivity (ec) of the water varies from 58.9 (minimum) to 1,098 μs.cm -1 (maximum) with a mean of 352.76 μs.cm -1 67% of water samples have conductivity greater than 200 μs.cm -1 while 23% have conductivity values less than 200 μs.cm -1 .the values of the sodium adsorption ratio (sar) range from 0.009 to 0.27, .the permeability index (pi) calculated for the analyzed water is between 49.74 and 225.90 %. the waters with pi values greater than 80% are considered to have a good permeability. below 25% the waters are considered poor permeability and unsuitable for irrigation. table-1.groundwater chemical composition of katiola area parameters units average minimum maximum ph 6.22 8.4 7.27 ec μs.cm -1 352.76 58.9 1,098 ca 2+ mg.l -1 29.22 8.02 72.14 mg 2+ 5.91 0.49 14.58 k + 1.88 0.12 6.18 na + 3.54 0.22 8.96 cl 13.14 3.55 49.64 hco3 148.85 18.3 396.5 so4 2 7.31 0 160 no3 4.49 0 33.5 sar % 0.14 0.009 0.27 pi % 84.48 49.74 225.90 4.2. sodium adsorption ratio (sar) the united states salinity laboratory’s diagram [13] relates the sar with the electrical conductivity (ec) of groundwater and places the samples in irrigation water categories (fig.4). the analysis of this figure reveals that the most of water samples fall in the section s1, class of low power alkalizing (sar) and are situated between c1 conductivities (low conductivity) and c2 (mean conductivity).these waters are generally suitable for irrigation of most cultivated species, without the risk of causing effects of permeability resulting from the exchangeable sodium asian review of environmental and earth sciences, 2015, 2(3): 54-60 58 percentage. it is observed in the diagram 4 samples, or 5% of the water falling into the c1s1 field. they are water samples. 33 (dousoulokaha) , 35 ( folonfokaha ), 5 (n'golodougou) and 11 (selile). 77 samples or 94 % of the water gather in the c2s1 category. only one sample (58) 1% of waters falls in the c3s1 field, and its represents the waters of ourougbankaha. these waters can’t be used generally for irrigation without prior dilution with water of low salinity [7]. figure-4. classification diagram of the katiola area groundwater for irrigation [15] 4.3. permeability index (pi) figure 5 is the representation of data on the doneen [10] diagram. calculated pi varies between 50 and 116%. in terms of permeability index, class iii represents the best types of water for irrigation. it includes the water samples like (9, 10, 11, 36, 42, 50, 52, 54, 57, 65, 71, 73, 74, 75, and 79). class ii, represents the water of an intermediate class quality and are likely used for irrigation, with certain precautions. it contains the water samples (39, 41, 46, 48, 49, 51, 53, 56, 59, 60, 76, 77, 78, and 80). class i, represents the water unsuitable for irrigation with samples as (20, 35, 38, 40, 43, 44, 45, 47, 58, 61, 72, 81, 82). therefore, the analysis reveals that about 29% of water samples are in class i, 33% in class ii and 38% in class iii. figure-5. doneen’s diagram of katiola groundwater samples asian review of environmental and earth sciences, 2015, 2(3): 54-60 59 4.4. mapping of groundwater’s suitability for irrigation to give practical meaning to this study, we mapped the ability of the area water for irrigation, according to the sar and permeability index (pi) (fig.6a). the first map (figure 6a) highlights three areas. the waters of excellent quality for agriculture (c1s1) are located in the south-west of the region. the highly mineralized poor quality waters are located in the extrem south-east (ourougbankaha). acceptable waters quality or intermediate (c2s1) take place in the rest of the area. the second map drawn according to the interpretation of doneen [10] (pi) (fig.6b) more or less confirms the observations from the first, and shows that the poor water quality for irrigation is located in the south-east of the study area. figure-6. maps of groundwater for irrigation in katiola area based on a) sar and b) permeability index (pi) 5. discussion the irrigation water requirements depend on the type of plant, soil and chemical water quality [2]. indeed soils containing high levels of sodium are notorious for having a bad soil structure [16]. for example, if the water used for irrigation has high concentrations of na + and low ca 2+ , the exchangeable ion complex (complex soil adsorbent) may be supersaturated in na + , thus destroying the soil structure, because of the dispersion of clay particles [3]. such soils can stunt the growth of the plant [17]. in addition, cheverry [14] shows that in a clay zone, very humus (10% of organic matter) with a biological activity "co2 producing " originally waters rich to bicarbonates are in equilibrium with the partial pressures of relatively high co2, and can be locally aggressive to the alkaline earth reserves sediments. when the capillary rise phase solutions throughout the profile several factors will contribute to make water “encrusting” and more dangerous for alkalinization. low salinity water whose electrical conductivity is lower than 200 μs.cm -1 have a strong trend to mobilize quickly calcium from soil, which promotes the dispersion of the particles and the clogging of pore spaces [4]. this problem could occur in the study area, with 23 % of the analyzed waters with ec values below 200 μs.cm -1 . two diagrams were used in this study to determine the quality of agricultural use of groundwater in the area. the sodium adsorption ratio as a function of the conductivity and doneen [10] pattern. sar reveals levels sodicity below 10%. so there is no risk of alkalinization of soils in the study area. this result is consistent with biémi [18] and soro [2] results, respectively in the regions of upper marahoué and grand lahou. the waters mainly fall into the c1s1 and c2s1 classes corresponding respectively to low and medium salinity water, hence low risk of alkalizing. the waters of class 1 are safe for most crops. those of class 2 are suitable for plants with low tolerance. on the other hand the stone fruit can accumulate dangerously sodium [2]. a single water sample (ourougbankaha) is located in the c3s1 class, which represent highly mineralized waters with lows risk of soil salinization. this water class is suitable for irrigation of some species much salt tolerant and well-drained soils and leached [19]. in the absence of an adequate drainage system, any use of this type of resource that does not include most frequent leaching of irrigated soils, leading to a gradual salinization and cause a significant decline in agricultural productivity, or even a loss irreversible fertile soils. this is lost in terms of production, meaning that, when soil salinization increases by improper irrigation with contaminated water, the productivity is lower. we can expect to falls in yields of some crops grown at the study area [4]. younsi [20] and debieche [21] reported that the permeability of the soil depends on several other factors such as the total concentration of water, the amount of sodium, the bicarbonate concentration and the nature of the soil. in the second graph based on the measurement of the index of permeability index, the waters are divided according to the three classes. the waters of the class i and ii have acceptable qualities intermediaries for irrigation. on the other hand, the waters of class iii are unsuitable quality for irrigation. their poor permeability may hinder the supply of water for cultivation. it makes it much harder farming practices on agricultural land. it bad for the lifting surface crusting (seal) produced by water logging [22]. these phenomena are associated with a number of disadvantages, including diseases, salinity, weeds and ventilation and nutrition problems [23]. the groundwaters in katiola area except for a few points are suitable quality (excellent) for agricultural use. however, it should be noted that the irrigation of agricultural areas by groundwater may present the risk of pollution to groundwater [9]. asian review of environmental and earth sciences, 2015, 2(3): 54-60 60 6. conclusion this study estimated the suitability of groundwater in the katiola area (agricultural area) for irrigation. following this work, we retain the majority of groundwater in the region with the exception of those located in the south-east sector are suitable quality for irrigation of most crops. these waters are generally low mineralized with sodicity levels well below to 15%, safe alkalizing or sodium binding to the complex soil adsorbent. in terms of permeability index, 71% have an intermediate water permeability index acceptable for irrigation. the highly mineralized waters poor in the south-east with significant risk of soil salinization, are likely suitable for the irrigation of some species much salt tolerant and well-drained soil and leached. in the absence of an adequate drainage system, any use of this type of resource that not include most frequent leaching of irrigated soils, leading to a gradual salinization and cause a significant decline in agricultural productivity, or even a loss irreversible fertile soils. references [1] a. t. tourè, "natural environment and humanization of lowland in subsoudanaise savannah," thesis of third cycle, national university of côte d’ivoire, 1992. [2] n. soro, "hydrochemistry and isotopic geochemistry of groundwater of grand-lahou square degree and surroundings (south west of côte d’lvoire). hydrological and hydrogeological involvement," thesis state of natural science, university of cocody-abidjan, côte d’ivoire, 2002. [3] k. todd, groundwater hydrology, 2nd ed. new york, usa: j. wiley & sons, 1980. [4] r. s. ayers and d. w. westcot, "water quality in agriculture. fao’s bulletin of irrigation and drainage," rév., vol. 29, pp. 1-165, 1988. [5] ins, "general census of population and housing 1998," socio-demographic et économic data: savannah region, 2001. [6] s. doumbia, "geochemistry, geochronology and structural geology of birimian rocks of katiola-marabadiassa area (center-north of côte-d'lvoire). magmatic evolution and geodynamic context of paleoproterozoic," phd thesis, university of orléans. france, 1997. [7] s. m. yidana, "groundwater classification using multivariate statistical methods: southern ghana," journal of african earth sciences, vol. 57, pp. 455-469, 2010. [8] g. sappa, s. ergul, and f. ferranti, "water quality assessment of carbonate aquifers in southern latium region, central italy: a case study for irrigation and drinking purposes," applied water science, vol. 4, pp. 115-128, 2014. [9] a. e. k. rouabhia and l. djabri, "irrigation and the risk of saline pollution. example of groundwaters from miocene aquifer in d’el ma el abiod plain," larhyss journal, vol. 8, pp. 55-67, 2010. [10] l. d. doneen, "the influence of crop and soil on percolating water," in proc. 1961 biennial conf. on groundwater recharge, 1962. [11] r. s. ayers and d. w. westcot, water quality for agriculture. rome: fao irrigation and drainage paper 29, rev. 1, 1994. [12] a. a. shaki and a. j. adeloye, "evaluation of quantity and quality of irrigation water at gadowa irrigation project in murzuq basin, southwest lybia," agricultural water management, vol. 84, pp. 193-201, 2006. [13] l. v. wilcox, classification and use of irrigation waters. washington d c: usd circular no. 969, 1955. [14] c. cheverry, "example of application of the work of us salinity laboratory (1963-1968) on alkalinization of soils subjected to bicarbonate waters," cah. orstom, série pédologique, vol. 10, pp. 193-203, 1972. [15] ussl, "diagnosis and improvement of saline and alkali soils," usda, handbook, vol. 60, p. 147, 1954. [16] c. a. j. appelo and d. postma, geochemistry, groundwater and pollution, 2nd ed. netherland: a. a. balkema publishers, 2005. [17] j. d. devedas, r. b. thirupathi, r. n. subla, a. subrahmanyam, and r. k. v. scinivasa, "hydrochemistry of the sarada river basin, visakhapatnam district, andhra pradesh, india," environ. geol., vol. 52, pp. 1331-1342, 2007. [18] j. biémi, "contribution to geological and hydrogeological study and by remote sensing of subsaheliens watershed of précambrian basement of south africa: hydrostructurale, hydrodynamic, hydrochemistry and isotopy of discontinuous aquifers of grooves and granitic area of high marahoué (côte d’lvoire)," ph.d. state thesis ès natural sciences, university of cocody, côte d’lvoire, 1992. [19] fao, "integrated management of natural resources, waters and soils of north africa," synthesis and proposals. bureau sous régional pour l’afrique du nord. tunis, 2003. [20] a. younsi, "highlighting mechanisms mthodology of salures of coastal groundwater in irrigated semi-arid zone," chaouia côtière, maroc. ph.d. state thesis, university of chouaib doukkali, el jadida, maroc, 2001. [21] t. h. debieche, "evolution of water quality (nitrogen salinity and heavy metals) on the effect of saline pollution, agricultural and industrial," ph.d. thesis of franche-comte, university, france, 2002. [22] a. benziane, n. boualla, and z. derriche, "suitability of waters basin form big sebkha of oran for irrigation," journal of applied biosciences, vol. 56, pp. 4066– 4074, 2012. [23] j. maait, "the reuse of wastewater for irrigation," bibliographic review. engref de montpellier, 1997. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 1, 1-8, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 1 organic petrological and geochemical evaluation of jurassic source rocks from north iraq mohamed m. el-kammar 1* --fuad s. hussein 2 --govand h. sherwani 3 1 geology department, faculty of science, cairo university, egypt 2 geology department, salahaddin university, iraq 3 ministry of natural resources, kurdistan region, iraq abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ................................................................................................................................................................................. 2 2. stratigraphy ................................................................................................................................................................................. 2 3. methodology ................................................................................................................................................................................ 3 4. results and discussions .............................................................................................................................................................. 3 5. conclusions .................................................................................................................................................................................. 8 references ........................................................................................................................................................................................ 8 immature jurassic oil shale is widely distributed and frequently outcropping in north iraq. the organic-rich jurassic sedimentary sequence, including prolific oil shale, was recorded in banik area in duhok governorate of north iraq. this sequence was systematically sampled from the geological formations; sehkanyian, sargelu and naokelekan. the organic geochemical parameters were analyzed for 72 samples as well as one oil sample. a detailed study of petrologic properties was carried out for 12 samples. based on toc content, the sargelu and naokelekan formations can be considered as good to excellent source rocks, whereas sehkanyian formation has no potential since the toc does not exceed 0.1 %. the samples of sargelu and naokelekan formations contain both kerogen types i and ii indicating marine organic matter mainly derived from algae and phytoplankton organisms proposing typical oil prone source kerogen. this is further confirmed by the predominance of alginite and liptodetrinite macerals, where liptinite maceral group contribute more than 90% relative to other maceral contents. in general, sargelu formation samples have production index (pi), tmax and fluorescence parameters (λmax and red/green quotient) suggesting immature to early mature stage of thermal maturity. the calculated ratios of pr/ph, pr/nc17 and ph/nc18for the extracted bitumen and the oil sample, suggest generation of bitumen from marine organic matter deposited under reducing conditions at an early thermal maturity stage. keywords: organic petrography, geochemistry, source rock, jurassic, kerogen, bitumen, iraq. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(1): 1-8 2 1. introduction the jurassic sedimentary sequence in northern iraq contains very significant source rocks owing to their high total organic carbon (toc) content, especially in both sargelu and naokelekan formations that were deposited throughout the jurassic basin that exists in these areas [1-3]. as far as the authors are aware, the published data on these source rocks are insufficient and the available information concerning the toc content, thermal maturation, and burial history require better understanding [4]. the dominant organic matter in oil shale is derived from one or more primary sources, such as terrestrial plants, lacustrine algae and marine organisms. these include large lake basins of tectonic origin, bogs, small lakes, lagoons and shallow seas [5]. banik section is situated in the far north of the iraqi territory, about 25 km to the ne of zakho town, (duhok governorate). the studied section lies on latitude 37°13′ 33.4" n and longitude 42° 58′ 2.6" e, to the west of banik village which is also known among resident farmers as banik haji ghazi. several mountains surround the area such as; kokharash to the north, khamtur to the west and shaban to the south (fig. 1). the present study deals with the hydrocarbon potential of the oil shale of the sargelu and naokelekan formations and their economic importance. 2. stratigraphy the jurassic rocks are commonly exposed as isolated patches at some eroded cores and limbs of anticlines in the highly folded, imbricate and thrust zones of northern iraq. the sedimentary section in banik area lies in a rugged terrain where the jurassic rocks crop out in the southern limb of kokharash anticline (mountain). the section is located close to the west of banik village near the open coal mine (dug in rocks of naokelekan formation). the general trend of strata is e-w. the stratigraphic succession starts with sarki and sehkanyian formations (early jurassic) which underlies sargelu formation (middle jurassic). the latter is overlain by the younger naokelekan and barsarin formations (late jurassic), with chia gara formation topping them (fig. 1). the lithologic composition of the sargelu formation consists of thinly bedded black bituminous limestone, dolomitic limestone and black papery shale intercalated by thin black streaks of chert in its upper part. in banik section, the thickness of sargelu formation is about 30 meters of which the limestone rocks are mostly dolomitized. in the subsurface sections, at the foothill and mesopotamian zone of the unstable shelf, the thickness is considerably higher and varies between 250 and 500 m jassim and buday [6]. fig-1. location map and the stratigraphic column of jurassic rocks crop-out in the banik area, north iraq indicating the collected samples. according to numan [7], the depositional history of the sargelu formation initiated and terminated as deep quiet marine environment, interrupted by some relatively shallow intervals but still remaining in the basinal realm. the organic–rich black shale and limestone of this formation indicate anaerobic to dysaerobic conditions [8]. such conditions are suitable for preservation of organic matter that gets thermally mature to generate hydrocarbon in subsequent geologic times. in some other subsurface sections, the behavior of the sargelu formation as potential source rock is provided by being seated at great depths [9]. the naokelekan formation consists of laminated bituminous limestone, alternated with bituminous shale (coal horizon) and thin bedded, highly bituminous dolomitie and limestone. its age is assigned as upper oxfordian–lower kimmeridgian according to the study of ammonites of the upper jurassic [10]. the depositional environment of the formation was interpreted as euxinic in a slow subsiding basin [11]. the boundaries of the formation are agreed by asian review of environmental and earth sciences, 2015, 2(1): 1-8 3 many researchers to be conformable and gradational with underlying sargelu formation and overlying barsarin formation. 3. methodology seventy two samples were collected to represent the targeted sedimentary interval in banik area as well as one oil sample from tawke oil field. the samples are collected along a traverse perpendicular to the bedding plane with spacing range of 0.5 to 1m. the collected samples represent the different lithologies of the sargelu, naokelekan and sehkanyian formations. analyses were conducted at strato chem services© company in cairo, egypt. the forty one samples that contain 0.7% toc, were analyzed by rock-eval pyrolysis. the measured parameters include; s1 (mg hc/g rock), s2 (mg hc/g rock), s3 (mg co2/g rock), tmax (°c), and toc (wt. %) are quoted in table 1. several additional parameters such as hydrogen index (hi = s2/toc*100), oxygen index (oi = s3/toc*100) and production index (pi = s1/(s1+s2)) are calculated (table 1). table-1. the ranges of the organic geochemical parameters of the jurassic studied samples are summarized in the following table. formation toc s1 s2 s3 tmax hi oi s1/ toc pi average average average average average average average average average (min:max) (min:max) (min:max) (min:max) (min:max) (min:max) (min:max) (min:max) (min:max) u. sargelu 4.12 0.21 37.17 1.53 443 366 39 4 0.02 (0.06:19.52) (0.03:1.05) (0.8 : 127.16) (0.08:4.89) (437 : 449) (96 : 697) (3:165) (1:16) (0.00:0.06) m.sargelu 2.4 0.24 24.92 1.26 443 317 29 9 0.04 (0.16:18.12) (0.04:0.43) (0.78:95.07) (0.20:3.96) (439:447) (103:525) (8:66) (2:24) (0.00:0.13) l. sargelu 8.82 0.72 62.62 1.83 443 446 32 6 0.02 (0.12:28.57) (0.04:2.45) (1.49:192.89) (0.45:3.78) (441:446) (57:690) (6:92) (2:12) (0.00:0.03) naokelekan 17.77 3.34 98.94 2.2 441 524 15 18 0.03 (5.39:25.55) (0.78:6.42) (18.05:149.1) (1.41:3.70) (434:445) (335:635) (8:32) (13:25) (0.02:0.04) sehkanyian 0.06 (0.03:0.09) gas chromatography (gc) and gas chromatography-mass spectrometry (gc-ms) were carried out to identify different hydrocarbon compound classes and biomarkers of the rock extracts and oil sample. organic petrologic examination of 12 samples was done, in the kurdistan institution for strategically studies and scientific researches, using dm 6000 leica microscope. identification of the maceral types was carried out under reflected and blue light illumination. the latter is necessary to recognize the fluorescing liptinite macerals. the classification schemes proposed for the interpretation of organic materials by teichmüller and ottenjann [12], teichmüller [13], borchan and powell [14], scott [15] were adopted in the present study. the change in the intensities of the fluorescence spectra of liptinite group was measured during ultraviolet irradiation over a wavelength range from 400 to 700 nm. 4. results and discussions pyrolysis techniques were used to establish the hydrocarbon source and the likely hydrocarbon products or source type. 4.1. organic matter richness the toc content of the study sediments can be considered as straight expression of kerogen and bitumen abundance. according to the classification given by peters and cassa [16], the upper part of the sargelu formation can be rated as having an excellent hydrocarbon potential (0.06% to 19.52%, averaging 4.12%) and the middle part as good hydrocarbon potential (0.16% to 18.12%, averaging 2.40%), whereas the lower part can be rated as an excellent hydrocarbon potential (0.12% to 28.57%, averaging 8.82%, table 1). the toc contents of the naokelekan formation range from 5.39% to 25.55 %, averaging 17.77% and can be considered as an excellent source rock. the sehkanyian formation has no source potential. 4.2. organic matter types it is necessary to recognize, that the quantitative aspects of kerogen evolution vary from one type to the other as a result of differences in the original composition of kerogen and that these generalizations may not reflect the true nature of the chemistry that occurs during the maturation process [17]. so, the types of organic matter must be distinguished and identified because different types of organic matter have different hydrocarbon generation potential and products [5, 18, 19]. the data of rock-eval pyrolysis (tables 1) indicate that sargelu formation plots generally in the field of kerogen type i and ii (fig. 2) which suggest common lacustrine depositional environment. the organic matter is mostly derived from marine algae and phytoplankton organisms which can be considered as a typical "oil source" kerogen dahl, et al. [20]. only one sample lies in the field of kerogen type iii which is derived mainly from terrestrial organic matter. naokelekan formation belongs to kerogen type i and is considered as excellent oil prone. the upper part of sargelu formation is characterized by localized intervals with capacity for both oil and mixed oil/gas generation. the oil-prone source rock intervals are characterized by very high toc (5.37%-19.52%) and excellent potential to generate oil as indicated by their high hydrogen indices (pyrolysis s2 yields from 32 to 127mg hc/g rock; and hi mostly >500 mg hc /g toc). the mixed-prone source rock intervals are characterized by low to very high toc (0.70%-8.13%) and fair to very good potential to generate oil and gas as indicated by their high hydrogen indices (pyrolysis s2 yields 2.60-19.03.16 mg hc/g rock; and hi mostly >200 mg hc /g toc). asian review of environmental and earth sciences, 2015, 2(1): 1-8 4 fig-2. van krevelen diagram, showing rock-eval hydrogen index vs. oxygen index for the analyzed samples of the study area (adapted from espitalié, et al. [21]) the middle part of the sargelu formation is characterized by having capacity for oil, mixed oil/gas and gas generation. the oil generating rocks are characterized by very high toc and very good to excellent potential to generate oil as indicated by their high hydrogen indices (pyrolysis s2 yields from 17 to 95mg hc/g rock; hi 365525 mg hc/g toc). the mixed oil/gas generating rocks are characterized by high toc (1.71%) and fair potential to generate oil and gas as indicated by their high hydrogen indices (pyrolysis s2 yields 4.15 mg hc/g rock; hi 242 mg hc/g toc). in addition the gas generating rocks are characterized by relatively high toc (1.81%) and fair potential to generate oil and gas as indicated by their high hydrogen indices (pyrolysis s2 yields 2.95 mg hc/g rock; hi 163 mg hc /g toc). lower part of sargelu formation is characterized by having capacity for oil, mixed oil/gas and gas generation. the oil-prone source rocks are characterized by their very high toc (2.34-28.57%) and very good to excellent potential for oil generation as indicated by their high hydrogen indices (pyrolysis s2 yields 14.75-192.89 mg hc/g rock; hi >400 mg hc /g toc). the mixed oil/gas prone source rocks are characterized by very high toc (4.29%) and good potential to generate oil and gas as indicated by their high hydrogen indices (pyrolysis s2 yields 8.83 mg hc/g rock; hi 206 mg hc /g toc). in addition the gas-prone source rocks are characterized by very high toc (3.28%) and fair potential to generate oil and gas as indicated by their high hi (pyrolysis s2 yields 3.50 mg hc/g rock; hi 107 mg hc /g toc). naokelekan formation is characterized by having capacity for both oil and gas generation. the oil-prone source rocks are characterized by very high toc (5.39-25.55%) and very good to excellent potential to generate oil as indicated by their high hydrogen indices (pyrolysis s2 yields 18.05-149.14 mg hc/g rock; hi >500 mg hc /g toc, fig. 3). the plotting of s1 versus toc can differentiate between the migrated and non-migrated hydrocarbons. the dividing line on the plot is where s1/toc = 1.5. values belonging to non-indigenous hydrocarbons plot above this line while indigenous hydrocarbon values emerge below it hunt [22]. thus all the samples analyzed of sargelu and naokelekan formations indicate indigenous hydrocarbons (fig. 4). fig-3. toc wt% versus s2 plot of sargelu and naokelekan formations indicates their hydrocarbon potentialities. asian review of environmental and earth sciences, 2015, 2(1): 1-8 5 fig-4. si versus toc for sargelu and naokelekan formations in banik section (modified after hunt [22]) 4.3. thermal maturity the maturity levels for the oil window depend on the type of organic matter [23], and encompass a vitrinite reflectance (ro) ranges from 0.5 to 1.3% and temperature at maximum rate of hydrocarbon generation during s2 evolution (tmax) from 435 to 470°c. the pi parameter is another measure of maturity, with values ranging from 0.15 to 0.4 normally associated with oil generation. hi versus tmax is commonly used to avoid influence of the oi for determining kerogen type [22]. determining kerogen type using hi versus tmax appears to be more accurate than oi versus hi. the difference between the results is expected because the sargelu and naokelekan formations are dominated by carbonates which affect the oi. the cross plot of hi versus tmax indicates dominance of kerogen typesi, ii and mixed type ii – iii in both sargelu and naokelekan formations (fig. 5). the samples are thermally immature to early stage of maturation, where pyrolysis tmax ranges from 437 449°c and pi is less than 0.15 [24]). fig-5. kerogon plots for hi vs. tmax of the samples of sargelu and naokelekan formations of the banik section. 4.4. rock extracts and oil gas-chromatography analysis was performed for the extract of 6 rock samples in addition to one oil sample (table 2). asian review of environmental and earth sciences, 2015, 2(1): 1-8 6 table-2. gas chromatograph data of the 6 extract samples of sargelu formation as well as the oil sample s. no. pri/phy pri/nc17 phy/nc18 cpi marzi 4 n paraffin isoprenoids resolved unknowns ext. 1 1.14 0.26 0.37 0.89 11.9 1.5 86.6 ext. 12 1.33 0.39 0.39 0.91 12.7 2.0 85.3 ext. 18 1.15 0.28 0.25 0.97 23.6 2.2 74.2 ext. 21 0.91 0.24 0.29 0.87 25.3 2.9 71.7 ext. 26 1.38 0.23 0.20 0.78 20.9 3.1 76.0 ext. 52 0.70 0.28 0.44 0.95 23.5 3.6 72.9 oil 0.73 0.26 0.44 0.98 30.8 3.8 56.5 the gas chromatograms of the extracts show a rather unimodal distribution pattern of the normal alkane with maximum intensity light ones (<n-c20) indicating autochthones source of the organic matter (fig. 6). the low content of hydrocarbon and the hump of the heavy hydrocarbon indicate that the samples are thermally immature. this is also certified by the low ratio of isoprenoid to normal alkane and the low pi parameter (< 0.10). the ratios of the pristane/phytane (pr/ph) in the 6 extracts are low (0.70 to 1.38), indicating anoxic reduced marine carbonate depositional environment. the organic-rich anoxic carbonate rocks generally generate oil with pr/ph ratio less than 2 [22, 25-27]. the carbon preference index (cpi) may be used as an indicator of maturation, where immature rocks often had cpi values more than 1.2 or less than 0.8. some marine sponges, fresh water aquatic plants, ferns, fungi, yeasts and bacteria have small odd carbon preferences [28]. the average of the cpi of the extracts of sargelu formation is less than 0.9 indicating marine source at early stage of maturation. the pr/nc17 (0.23-0.39) and ph/nc18 (0.20-0.44) ratios reflect deposition under reducing marine condition rather than effect of maturity or biodegradation (fig. 7). the gas-chromatograms of the oil sample recovered from north iraq at 2840 m of sargelu formation reveal n-alkane distribution pattern in the n-c4 to n-c41 range (fig. 6) with api value of 29.85º. the oil sample has low pr/ph ratio (0.73), which together with the pr/n-c17 (0.26) and ph/n-c18 (0.44) suggests generation from a source rock containing mainly marine organic matter deposited under reducing depositional conditions (fig. 7). fig-6. gas chromatograms of the rock extract of the sargelu formation and it oil sample from north iraq. fig-7. pr/n-c17 versus ph/n-c18 of the sargelu formation extracts and the oil samples. asian review of environmental and earth sciences, 2015, 2(1): 1-8 7 4.5. maceral analysis the majority of kerogen in the investigated samples belongs to liptinite maceral group (mostly of alginite and liptodetrinite), where the abundance of this group ranges from 85% to 99% relative to other maceral contents, on mineral matter free basis (table 3). table-3. the maceral composition and the fluorescence properties of the oil shales of sargelu formation in banik area, north iraq. formation liptinite mineral fluoresceneproperties alginite liptodetrinite bituminite matrix vol% λmax (nm) q average average average average average average (min:max) (min:max) (min:max) (min:max) (min:max) (min:max) u. sargelu 45.67 21.67 32.67 70.00 520.00 0.66 (45:46) (20:24) (30:35) (68:74) (515:525) (0.60:0.72) m.sargelu 31 37 32 65 520 0.73 (23:36) (23:68) (19:50) (55:83) (515:530) (0.63:0.81) l. sargelu 54.33 15.00 30.67 57.33 526.67 0.63 (45:60) (13:17) (25:40) (56:58) (520:530) (0.62:0.64) blue light is necessary to recognize the fluorescing liptinite maceral as the major portion of the hydrogen-rich organic material, where it is invisible in normal reflected light (fig. 8). it occurs in the form of thin wall layer with length ranging from 100 to 300 µm in the form of multifolded around foraminiferal chamber that is filled with framboidal pyrite and spheromorph bodies within the mineral matrix. the liptodetrinite macerals reach 10 µm in length and display fluorescence intensity similar to that of alginite (fig. 8). fig-8. p petrographic characteristics of sargelu oil shale samples from banik area, northern iraq. alginites and bituminite a & c (blue light) x200 b & d (reflected light) x200 they were observed frequently in all samples. liptodetrinite macerals cannot be assigned to a specific source because it consists of fragments of degraded remains of spores, cuticles, resinous bodies or algae [13]. the predominance of the liptinite maceral group and the presence of pyrite in all analyzed samples indicate organic material of marine origin deposited under anoxic environment. bitumen like materials was frequently observed in all samples. according to teichmüller and ottenjann [12] bituminite macerals, which are decomposition product of algae, animal plankton and bacterial lipids, can be classified, in the present work, into two types; i and ii. bituminite "type i" occurs as lenticular bodies ranging from 100 to 150 µm in length and displays orange to brownish fluorescence in blue light. bituminite "type ii" displays petrographic characteristics similar to those of vitrinite. it occurs as oval or elliptical bodies with dark brown fluorescence color of very low intensity (fig. 8). quantitative methods have been developed to relate the changes in florescence properties (λmax and q values) to the geothermal rank [29]. alginites are the best for rank evaluation, where cutinites and resinites are not suited for maturation evolution because they show varying fluorescence at a given rank stage [13]. the obtained data of λmax values for alginite of the studied samples range from 515 to 530 nm and red/green quotient values range from 0.6 to 0.8. these values indicate low maturity level of the studied source rocks. asian review of environmental and earth sciences, 2015, 2(1): 1-8 8 5. conclusions the jurassic source rocks in north iraq have been assessed for their hydrocarbon potential. a total of 72 rock samples from sehkanyian, sargelu and naokelekan formations were analyzed by rock-eval /toc pyrolysis and selected 12 samples were prepared for organic petrologic examination as well as 6 rock extract and an oil sample were analyzed by gc/gcms. in general, the sargelu and naokelekan formations have kerogen types i and ii of lacustrine depositional environment in immature to early mature stage of thermal maturity. they can be considered as good to excellent source while the sehkanyian formation has no potential. the predominant macerals of the sargelu formation belong to liptinite group (alginite and liptodetrinite).the λmax values for alginite of the studied samples and red green quotient values indicate low maturity level of the studied rocks. the extracted bitumen samples from sargelu formation show diagnostic ratios of pr/ph, pr/nc17 and ph/nc18 for generation oil at an early thermal maturity stage. the low pr/ph ratio of the analyzed oil sample together with the low pr/n-c17 and ph/n-c18 suggest that the oil was generated from a source rock containing mainly marine organic matter deposited under reducing conditions. references [1] s. z. jassim and m. al-gailani, hydrocarbons. in: jassim and goff (eds). geology of iraq. brno: czech republic, prague and moravian museum, 2006. [2] g. h. sherwani and s. m. balaky, "black chert, an interesting petrographic component within the upper part of sargelu formation (middle jurassic) – north and northeastern iraqi kurdistan," iraqi bull. geology and mining, vol. 2, pp. 77-88, 2006. [3] r. abdula, "petroleum source rock analysis of the jurassic sargelu formation, northern iraq," m sc. thesis, faculty of trustees of the colorado school of mines, 106, 2010. [4] j. k. pitman, d. steinshouer, and m. d. lewan, "petroleum generation and migration in the mesopotamian basin and zagros fold belt of iraq result from a basin-modeling study," gulf petrolink bahrain, vol. 9, pp. 41-72, 2004. [5] b. p. tissot and d. h. welte, petroleum formation and occurrence, 2nd ed. berlin: springer-verlag, 1984. [6] s. z. jassim and t. buday, late toarcian-early tithonian (mid-late jurassic) megasequence ap7. in: jassim and goff (eds). geology of iraq. brno: czech republic, prague and moravian museum, 2006. [7] n. m. numan, "major cretaceous tectonic events in iraq," rafidain jour. sci., vol. 11, pp. 32-54, 2000. [8] e. g. kauffman and b. b. sageman, biological sensing of benthic environments in dark shales and related oxygen – restricted facies. in ginsburg and beaudoin (eds). cretaceous resources, events and rhythms background and plans for research vol. 352. london: kluwer academic publishers, 1990. [9] s. m. ahmed, "source rock evaluation of naokelekan and barsarin formations (upper jurassic) in northern iraq," m sc thesis, university of sulaimani, 172, 2007. [10] r. c. bellen, h. v. van dunnington, r. wetzel, and d. m. morton, "luxique stratigraphique international," asie, fascicule10a, iraq, paris, 1959. [11] t. buday, the regional geology of iraq. stratigraphy and paleogeography vol. 1: dar al-kutub publishing house, university of mosul iraq, 1980. [12] m. teichmüller and k. ottenjann, "art und diagenese von liptiniten und lipoiden stiffen in einemerdölmuttergestein auf grundfluoreszenzmikroskopischeruntersuchungen," erdöl and khole, vol. 30, pp. 387-397, 1977. [13] m. teichmüller, "the genesis of coal from the viewpoint of coal petrology," int. j. coal geol., vol. 12, pp. 387-397, 1989. [14] c. j. borchan and t. g. powell, "petroleum source rock potential of coal and associated sediments: qualitative aspects," aapg bull: special pub., vol. a180, pp. 133-157, 1993. [15] a. c. scott, "coal petrology and the origin of coal macerals: a way ahead," int. j. coal geol., vol. 50, pp. 119–134, 2002. [16] k. e. peters and m. r. cassa, "applied source rock geochemistry. in: magoon, l.b., dow, w.g. (eds.): the petroleum system from source to trap," aapg, mem., vol. 60, pp. 93-117, 1994. [17] j. g. speight, the chemistry and technology of petroleum, 4th ed.: crc press is an imprint of the taylor & francis group, 2007. [18] j. brooks, organic maturation studies and fossil fuel exploration vol. 360. london: academic, 1981. [19] r. v. tyson, sedimentary organic matter. organic facies and palynofacies. london: chapman and hall, 1995. [20] b. dahl, j. bojesen-koefoed, a. holm, h. justwan, e. rasmussen, and e. thomsen, "a new approach to interpreting rock-eval s2 and toc data for kerogen quality assessment," organic geochemistry, vol. 35, pp. 1461-1477, 2004. [21] j. espitalié, j. l. laporte, m. madec, f. marquis, p. leplat, and j. paulet, "rapid method for source rocks characterization and for determination of petroleum potential and degree of evolution," revue de l'institutfrançais du pétrole (ifp), vol. 32, pp. 23-42, 1997. [22] j. m. hunt, petroleum geochemistry and geology, 2nd ed. vol. 743. new york: freeman and company, 1996. [23] c. a. bacon, c. r. calver, c. j. boreham, d. e. leaman, k. c. morrison, and a. t. revill, "the petroleum potential of onshore tasmania-a review," geol. surv. bull., vol. 71, p. 93, 2000. [24] j. k. pitman, k. j. franczyk, and d. e. anders, "marine and non marine gas-bearing rocks in upper cretaceous blackhawk and nelsen formations, eastern unit basin, utah. sedimentology, diagenesis, and source rock potential," aapg bull, vol. 71, pp. 76-94, 1987. [25] k. e. peters and j. m. moldowan, the biomarker guide-interpreting molecular fossils in petroleum and ancient sediments vol. 363. new jersey, englewood cliffs: prentice-hall, 1993. [26] w. b. hughes, a. g. holba, and l. i. p. dzou, "the ratios of dibenzothiophene to phenanthrene and pristane to phytane as indicators of depositional environment and lithology of petroleum source rocks," geochimicaet cosmochimica acta, vol. 59, pp. 3581-3598, 1995. [27] k. e. peters, c. c. walters, and j. m. moldowan, the biomarker guide. biomarkers and isotopes in petroleum systems and earth history, 2nd ed.: united kingdom at the cambridge university press, 2005. [28] j. m. moldowan, w. k. seifert, and g. e.j., "relationship between petroleum composition and depositional environment of petroleum source rocks," aapg bull, vol. 69, pp. 1255-1268, 1985. [29] k. ottenjann, "improved microphotometric fluorescence measurements of coal macerals," zeiss information, vol. 26, pp. 40-46, 1983. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn(e) : 2313-8173 issn(p) : 2518-0134 vol. 3, no. 1, 18-26, 2016 http://www.asianonlinejournals.com/index.php/arees 18 ionizing radiation leakage in radio-diagnostic centers at gaza strip hospitals, palestine samer s. abu zer1 khalid j. khadoura2  samir s. yassin3 mohamed r. al agha4 1 radiology department, shifa hospital, gaza strip, palestine occupied 2 head nurse of internal medicine dep., shifa hospital, faculty of nursing, the islamic university of gaza, palestine . 3 physics department, the islamic university of gaza. 4 environment and earth science department, the islamic university of gaza. ( corresponding author) abstract the fact of using radiation in medicine has led to major improvements in the diagnostic and treatment of human diseases. however, it carries some risks of health problems. in gaza governorates hospitals, there is tremendous development has taken place in the radio-diagnostic field and there is no clear radiation protection program, lack of clear information about radiation protection measures and guidelines. the objective of this study was an assessment whether yearly equivalent radiation dose received by the radiodiagnostic workers and public in governmental gaza governorates hospitals are within the dose limits recommended by icrp or not. the study was carried out in nine governmental hospitals. the hospitals were selected because of their large and diverse of their radio-diagnostic services. the radiation survey meter (od-01) was used to measure radiation leakage. data sheet was also used to elicit information about the radio-diagnostic rooms and machines specifications. the results indicate that the fluoroscopy and ct scan rooms were not efficiently lead lined and the radiation protection is not well organized. the measured values of radiation dose rate at different locations in basic x-ray and mammography rooms are found within a permissible limits for occupational stuff and public. however, the recommended distance between the x-ray machine and control panel have not been achieved in some rooms. therefore, there is a desperate need for rules, regulations and radiation protection act in the field of radiation in medical field. keywords: radiation protection, radio-diagnostic, equivalent radiation dose rate, workload. contents 1. introduction ......................................................................................................................................................................... 19 2. objectives ............................................................................................................................................................................. 19 3. materials and methods ........................................................................................................................................................ 19 4. results and discussion ......................................................................................................................................................... 20 5. conclusion ............................................................................................................................................................................ 26 references ................................................................................................................................................................................ 26 citation | samer s. abu zer; khalid j. khadoura; samir s. yassin; mohamed r. al agha (2016). ionizing radiation leakage in radio-diagnostic centers at gaza strip hospitals, palestine. asian review of environmental and earth sciences, 3(1): 18-26. issn(e) : 2313-8173 issn(p) : 2518-0134 doi: 10.20448/journal.506/2016.3.1/506.1.18.26 this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group http://creativecommons.org/licenses/by/3.0/ http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.18.26 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=khalid j. khadoura https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.18.26 asian review of environmental and earth sciences, 2016, 3(1): 18-26 19 1. introduction recently, tremendous development has taken place in the radio-diagnostic field at governmental gaza governorates hospitals. newer modalities are being applied in hospitals and latest radiological machines are recently obtained. besides, there is a noticeable increase year after year in the frequency of radiological procedures. this quantitative increase may have a positive impact on the health service system of the country, but the lack of control can cause serious problem especially radiation hazard to the radiation workers as well as public. ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized. ionizing radiation has been putting to use in diagnosis of various diseases and treatment since its discovery in 1895 by wilhelm conrad rontgen [1]. the radiological protection principles in practical field, the optimization of protection and the individual dose limitation should be continuously performed. dose limitation for occupationally exposed individuals is necessary to reduce the level of risk and ensures safety for workers. knowledge and education have strong direct effects in technical protection against health hazards associated with radiation exposures [2]. it is advisable that assessing radiation doses received by radiology workers at periodic intervals will ensure their occupational safety [3]. personal radiation monitoring is essential to ensure that dose limits for staff are not exceeded. the accepted effective annual dose limits for occupational staff as reported by the international commission on radiological protection (icrp) in 1977 was 50 msv. public should not be exposed to more than an average of 1 msv per year. a downward review was done in 1991 and an effective annual dose limit of 20 msv was adopted as an average for a period of five years, with the further provision that the effective dose should not exceed 50 msv in any single year. the downward review of annual dose limit was adopted in order to put a stricter control over the use of ionizing radiation in medicine and minimize possible hazards, especially the stochastic effects [4]. 2. objectives the main objective of the study is to measure of ionizing radiation level inside and outside of radio-diagnostic rooms to assess whether yearly equivalent radiation dose received by the radio-diagnostic workers and public are within the dose limits recommended by icrp or not and to evaluate of radiation protection measures in radiodiagnostic centers at governmental gaza governorates hospitals. the other specific objectives are:  to assess whether annual equivalent dose received by the radiation workers are within the dose limits recommended by icrp or not.  to identify the dangerous locations in radio-diagnostic centers.  to evaluate of radiation protection status in radio-diagnostic rooms.  to make an inventory of availability of radio-diagnostic machines of the surveyed hospitals.  to help the planners and decision makers to modify the future plans regarding radiation protection to be more and to develop radiation safety culture. 3. materials and methods the study was carried out in radio-diagnostic centers at nine selected governmental gaza governorates hospitals including: al shifa medical complex, nasser medical complex, european gaza hospital, abu yousef al najjar martyr hospital, kamal adwan martyr hospital, al aqsa martyrs hospital, abdel aziz rantessi martyr hospital, al naser pediatric hospital and beit hanoun hospital. the hospitals were selected because of their large and diverse of their radio-diagnostic services. two ways were applied to assess the status of ionizing radiation dose rate and radiation protection measures in radio-diagnostic centers at governmental gaza governorates hospitals, namely:  radiation survey  radio-diagnostic machines and rooms specifications data sheets the radiation survey has been carried out to measure the radiation dose rate indifferent locations in the radiodiagnostic rooms at nine governmental gaza governorates hospitals which include: 19 basic x-ray, 8 fluoroscopy, 1 mammography and 3 ct scan rooms. the radiation dose rate in this study was carried out using radiation survey meter (od-01) that designed by step – sensotechnik and elektronikpockau gmbh, germany. figure (1) displays the radiation survey meter that used throughout the measurements. the calibration of the survey meter (od-01) is performed according to iso 9001 tuv quality management system certification, headquartered in munich, germany by using co-60 (photon energy 1.2 mev). figure-1. radiation survey meter (od-01) asian review of environmental and earth sciences, 2016, 3(1): 18-26 20 to measure the equivalent radiation dose rate, specific locations were selected according to radio-diagnostic rooms design and machines types. these locations are: directional dose rate, at one meter distance from the x-ray tube by closing the tube collimators, at control panel, at corridor outside the x-ray room (door closed), at dark room and behind the chest stand wall. for ct scan the measurements also conducted at door near the control panel (door closed), in additional to patient waiting rooms. the measurements were performed during the daytime between 8 am to 2 pm. the electrical zero balancing was recorded before the radio-diagnostic machines were switched on in respective rooms to verify the electrical zero of the measuring device. the reference phantom was used as a scattering medium to simulate physiological characteristics of patient body. the measurements behind the chest stand wall was done without a patient or a phantom and the distance between x-ray tube and chest stand equal 180 cm. the measurements were conducted by using source image distance (sid) is equal 100 cm. in this study the radiation level at each location was calculated using the workload. the national council on radiation protection and measurements (ncrp report no. 49) workloads could be used throughout this work. however, the ncrp workloads might be more or less than the workloads at some of those rooms. for this reason, can be calculated the workloads in each radio-diagnostic room to simulate the real workloads in radio-diagnostic rooms at governmental gaza governorates hospitals. the radiation level at each location in one week was calculated using the workload ma.min/week (= mas/60), the current workload in each room could be calculated as: workload ∑ i.ni where ni is examination number of type i and ma·min used for type i [5]. in order to calculate the radiation level in different locations, we have considered the different characteristic parameters of radiation like kilo-volt (kv), milli-ampere (ma) and time (s). in basic x-ray, the radiation parameters taken to evaluate radiation level were about 100 kvp in voltage, 1 s in time (t), and tube current (i) was 100 ma, to give high energy of radiation. in ct scan, the radiation parameters taken to evaluate radiation level were about 100 kvp in voltage, 1 s in time (t), and tube current (i) was 210 ma. in fluoroscopy, the radiation parameters taken to evaluate radiation level were about 100 kvp in voltage, tube current (i) was 3 ma. in mammography, the radiation parameters taken to evaluate radiation level were about 30 kvp in voltage, 1 s in time (t), and tube current (i) was 50 ma. the equivalent radiation dose rate to whole body at each location (hw) in unit of ( ) was calculated using: ( ) ( ) d ( ) where is the equivalent dose rate level readings in air at each point in units of (msv/min); intensity (im ) in ma units and workload in units of ( ) [6]. data sheets are also used to obtain information about radio-diagnostic machines and rooms. the information was taken from medical equipment engineering department in ministry of health and from the head of radio-diagnostic center. the data sheet includes information about: name of hospital, radio-diagnostic room number, manufacturer of machine, model of machine, status of machine, date of machine installation, type of machine working (constant or portable), (electronic or manual), (film processing digital or analogue), dimensions of radio-diagnostic room in cm, width of the room walls in cm, material of the room walls, material of the control panel wall, thickness and high of lead lining the room walls, the distance between the radiation source and control panel, thickness of lead lining the room doors and number of radiological procedures in the radio-diagnostic room per day. 4. results and discussion 4.1. the equivalent radiation dose rate 4.1.1. the equivalent radiation dose rate at control panels the measured values of equivalent radiation dose rate at control panels are carried out in radio-diagnostic rooms at nine selected hospitals shown in figure (2). the results could be accepted and remain within permissible limit for occupational stuff. we have also noticed that the ct scan room at al shifa medical complex ranked the first in term of the highest radiation dose rate, and gives (14.2 msv/yr). then followed by fluoroscopy room at nasser medical complex, and gives (10.9 msv/yr). in addition , the higher values at control panels for basic x-ray rooms found in emergency room at kamal adwan hospital and at emergency room at al shifa hospital, and gives ( 4.03 msv/yr and 3.8 msv/yr) respectively. the lowest radiation dose rate at control panel found in mammography room at nasser medical complex. asian review of environmental and earth sciences, 2016, 3(1): 18-26 21 figure-2. the equivalent radiation dose rate at control panels 4.1.2. the equivalent radiation dose rate at corridors figure (3) illustrates the measured values at corridors during closing the doors in thirty radio-diagnostic rooms at nine selected hospitals. the results showed that the values at ct scan , fluoroscopy, and some of basic xray rooms are higher than the reference limit for public exposure and indicate that the doors that leads to these rooms should be efficiently lead lined. clearly, there is a health risk of radiation exposure for people who visiting this rooms. certainly, this would give notice to the stakeholders for an adequate protection. however, the measured values for the rest rooms were found within the permissible limits and the lowest radiation dose rate was found in mammography room at nasser medical complex. figure-3. the equivalent radiation dose rate at corridors asian review of environmental and earth sciences, 2016, 3(1): 18-26 22 4.1.3. the equivalent radiation dose rate at patient waiting rooms figure (4) exhibits the measured values at patient waiting rooms in nine radio-diagnostic rooms at nine selected hospitals. the results could be described the most of equivalent radiation dose rate are higher than the reference limits for public exposure. the results showed that the values in patient waiting room at ct scan room at al shifa medical complex are the higher compared the reference limit for public exposure and indicate that the doors that leads to these rooms should be efficiently lead lined. however, the lowest radiation dose rate was found in patient waiting room at ct scan room at nasser medical complex. figure-4. the equivalent radiation dose rate at patient waiting rooms 4.1.4. the equivalent radiation dose rate at dark rooms figure (5) describes the measured values in twenty first dark rooms at nine selected hospitals. it is noticed that the dark rooms near the fluoroscopy rooms ranked the first in terms of the highest radiation dose rate. figure-5. the equivalent radiation dose rate at dark rooms 4.1.5. directional equivalent radiation dose rate and at one meter from the x-ray tube in basic x-ray and mammography rooms figure (6) illustrates the difference between the directional radiation dose rate and the radiation dose rate at one meter distance from the x-ray tube by closing the collimators in basic x-ray and mammography machines. this asian review of environmental and earth sciences, 2016, 3(1): 18-26 23 indicates to the importance of using radiation protection techniques such as the distance from the x-ray source and x-ray beam collimators. all x-ray tubes have some radiation leakage, there is only 2-3 mm lead in the housing. radiation leakage is limited in most countries to 1 mgy/hr at 1 meter, so this can be used as the actual leakage value for shielding calculations [5]. the directional radiation dose rate in basic x-ray machine in room no. 2 at kamal adwan martyr hospital was about (162.9msv/yr), while the radiation leakage at one meter distance from the x-tube by closing the collimators about (4.4msv/yr).this reflects the importance of using the distance from the x-ray source and x-ray tube collimators to protect the patients and their escorts. figure-6. directional equivalent radiation dose rate and at one meter from the x-ray tube in basic x-ray and mammography rooms 4.1.6. directional equivalent radiation dose rate and at one meter from the x-ray tube in fluoroscopy and ct scan rooms figure-7. directional equivalent radiation dose rate and at one meter from the x-ray tube in fluoroscopy and ct scan rooms asian review of environmental and earth sciences, 2016, 3(1): 18-26 24 the measurements are also performed for both fluoroscopy and ct scan machines at the selected hospitals. figure (7) describes the deference between the directional radiation dose rate and the radiation dose rate at one meter distance from the x-ray tube by closing the collimators in fluoroscopy rooms. the difference between the directional radiation dose rate in ct scan machine at al shifa medical complex (1338.12 msv/yr), and the radiation dose rate at one meter distance from the x-ray tube (752.976 msv/yr), refers to a huge radiation dose inside the ct scan rooms during imaging the patient. this high dose rate indicates a high health risk to the unsuspecting supportive persons such as nurses, hospital attendants and patient escorts. such dose rate could pose more serious problem to a pregnant women. so, it is importance of evacuating the ct scan room from the patient escorts before giving the x-ray dose. 4.2. specifications of radio-diagnostic machines and rooms at the selected hospitals data sheet information were collected and analyzed for all radio-diagnostic machines and rooms that available in the selected hospitals. the information was taken from medical equipment engineering department in ministry of health and from the head of radio-diagnostic center. the analysis shows the most of these machines are installed recently, working electronically. the results of analysis show that all of radio-diagnostic rooms space less than the ideal x-ray rooms space, that should not be less than 36 m 2 according to (ncrp, report no. 147).the recommended distance between the x-ray machine and control panels have not been achieved in some rooms such as: emergency basic x-ray room at al shifa medical complex, fluoroscopy room at nasser medical complex, basic x-ray room no. 4 at european gaza hospital, emergency basic x-ray room at abu yousef al najjar martyr hospital, basic x-ray in emergency room and fluoroscopy room at kamal adwan martyr hospital, basic x-ray room at al naser pediatric hospital and basic x-ray room at beit hanoun hospital. the thickness and materials of the x-ray rooms walls (20 cm and cement) respectively. the thickness and height of lead lining of room walls (2 mm and 200-210 cm) respectively. the thickness of lead lining the room doors (2 mm), this is in conformity with safety standards. however, we found that the wall of the control panel in some rooms made of wood lined with lead thickness 2 mm, this is not compatible with alara principle. table-1. radio-diagnostic machines and rooms specifications data sheet name of hospital name of machine and room number thickness and height of lead lining of room walls width of room walls/cm type of machine working (electronic or manual) distance between the xray tube and control panel material of room walls date of installation no. of radiological procedures per day material of control panel wall room dimensions /cm nasser medical complex fluoroscopy and basic x-ray room no. 2 electronic 20 cm 2 mm 200-210 cm 2007 cement 200 cm 490 x 380 wood 2 mm basic x-ray emergency room electronic 20 cm 2 mm 200-210 cm 2005 cement 150 cm 410 x 410 wood 2 mm basic x-ray room no. 2 electronic 2 cm 2 mm 200-210 cm 2002 cement 330 cm 570 x 420 cement 2 mm basic x-ray room no. 4 electronic 20 cm 2 mm 200-210 cm 2007 cement 140 cm 480 x 415 cement 2 mm eswel (lithotripsy) fluoroscopy room electronic 20 cm 2 mm 200-210 cm 2011 cement 300 cm 600 x 500 cement 2 mm portable basic x-ray room no. 1 electronic 20 cm 2 mm 200-210 cm 2008 cement 220 cm 580 x 450 wood 2 mm basic x-ray room no. 2 electronic 20 cm 2 mm 200-210 cm 2006 cement 230 cm 520 x 450 wood 2 mm mammogra-phy room no. 3 electronic 20 cm 2 mm 200-210 cm 2011 cement 30 cm 360 x 300 leaded glass 2 mm continue asian review of environmental and earth sciences, 2016, 3(1): 18-26 25 fluoroscopy room no. 4 electronic 20 cm 2 mm 200-210 cm 2011 cement 160 cm 580 x 430 cement 2 mm c.t scan room no. 5 electronic 20 cm 2 mm 200-210 cm 2006 cement 290 cm 480 x 430 cement 2 mm basic x-ray out clinic room electronic 20 cm 2 mm 200-210 cm 2012 cement 240 cm 500 x 370 wood 2 mm shifa medical complex fluoroscopy room no. 1 electronic 20 cm 2 mm 200-210 cm 2009 cement 280 cm 600 x 580 cement 2 mm fluoroscopy room no. 2 electronic 20 cm 2 mm 200-210 cm 2013 cement 300 cm 460 x 450 cement 2 mm basic x-ray room no. 6 electronic 20 cm 2 mm 200-210 cm 2012 cement 240 cm 450 x 350 cement 2 mm basic x-ray room no. 7 electronic 20 cm 2 mm 200-210 cm 1997 cement 250 cm 580 x 340 wood 2 mm c.t scan room electronic 20 cm 2 mm 200-210 cm 2011 cement 330 cm 500 x 450 cement 2 mm basic x-ray emergency room electronic 20 cm 2 mm 200-210 cm 2011 cement 180 cm 600 x 400 cement 2 mm basic x-ray out clinic room no.1 electronic 20 cm 2 mm 200-210 cm 2009 cement 260 cm 400 x 380 cement 2 mm basic x-ray out clinic room no. 2 electronic 20 cm 2 mm 2 m 2005 cement 250 cm 400 x 360 cement 2 mm al aqsa martyrs hospital basic x-ray room no. 1 electronic 20 cm 2 mm 200-210 cm 2002 cement 310 cm 500 x 450 wood 2 mm fluoroscopy and basic x-ray room no.2 electronic 20 cm 2 mm 200-210 cm 2007 cement 330 cm 450 x 360 wood 2 mm al naser pediatric hospital basic x-ray room no.1 electronic 20 cm 2 mm 200-210 cm 2011 cement 100 cm 500 x 400 wood 2 mm abdel aziz rantessi martyr pediatric hospital fluoroscopy room no. 1 constant 20 cm 2 mm 200-210 cm 2011 cement 230 cm 480 x 440 cement 2 mm c.t scan room no. 2 constant 20 cm 2 mm 200-210 cm 2008 cement 280 cm 550 x 450 cement 2 mm kamal adwan martyr hospital basic x-ray emergency room electronic 20 cm 2 mm 200-210 cm 2011 cement 150 cm 550 x 390 wood 2 mm basic x-ray room no. 2 electronic 20 cm 2 mm 200-210 cm 2010 cement 200 cm 500 x 390 wood 2 mm continue asian review of environmental and earth sciences, 2016, 3(1): 18-26 26 beithanoun hospital basic x-ray room no. 1 electronic 20 cm 2 mm 200-210 cm 2011 cement 160 cm 400 x 260 wood 2 mm 5. conclusion in the present work, radiation level measurements for radio-diagnostic centers was carried out in nine selected governmental hospitals at gaza governorates. these include: 19 basic x-ray, 8 fluoroscopy, 1 mammography and 3 ct scan machines. in general, the results indicate that the fluoroscopy and ct scan rooms were not efficiently lead lined and the radiation protection is not well organized. since, the measured values at corridors during closing the doors and at patient waiting rooms in fluoroscopy and ct scan rooms suggests very high exceedance compared to the reference limit for public exposure. thus, it is noticed that a health risk of radiation exposure for all persons who visiting these rooms. also, the measured equivalent radiation dose rate at control panels give high doses values, but remain in the permissible limit for radiology workers. however, there is an impending risks of chronic occupational exposure to the employees. moreover, the equivalent radiation dose rate that measured at a different locations in basic x-ray and mammography rooms are found within the permissible limits for radio-diagnostic workers and public. this indicates that these rooms are built safe and well organized according to safety criteria. also, the results suggest that the importance of using radiation protection techniques such as the distance from the x-ray source and x-ray beam collimators. whereas, the recommended distance between the x-ray machines and control panels have not been achieved in some rooms. references [1] world health organization (who), "what is ionizing radiation?" available http://www.who.int/ionizing_radiation/about/what_is_ir/en/index.html, 2009. [2] m. mojiri and a. moghimbeigi, "awareness and attitude of radiographers towards radiation protection," journal of paramedical sciences, vol. 2, p. 497, 2008. [3] f. ujah, n. akaagerger, e. agba, and j. iortile, "a comparative study of patients radiation levels in federal standard diagnostic reference levels in federal medical center and bishop murray hospitals in makurdi," archives of applied science research, vol. 4, pp. 800-804, 2012. [4] z. ibitoye, m. aweda, and n. irurhe, "annual effective dose status among the radiation staff of lagos university teaching hospital, lagos, nigeria," african journal basic and appl., vol. 3, pp. 126-130, 2011. [5] icrp, the 2007 recommendations of the international commission on radiological protection. oxford, uk: elsevier, 2007. [6] k. adhikari, l. jha, and m. galan, "status of radiation protection at different hospitals in nepal," journal of medical physics, association of medical physicists of india, vol. 37, pp. 240-244, 2012. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://www.who.int/ionizing_radiation/about/what_is_ir/en/index.html, asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no.3, 66-83, 2014 http://www.asianonlinejournals.com/index.php/arees * corresponding author 66 petrostructural and mineralogical assessment of the precambrian rocks in ikere area, southwestern nigeria olusiji samuel ayodele 1* --segun ajayi akinyemi 2 1,2 department of geology, ekiti state university, ado-ekiti. nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 67 2. location of the study area ....................................................................................................................................................... 67 3. charnockites .............................................................................................................................................................................. 68 4. results ........................................................................................................................................................................................ 68 5. discussion ................................................................................................................................................................................... 81 6. conclusion .................................................................................................................................................................................. 82 references ...................................................................................................................................................................................... 82 petrological and mineralogical evaluation of the basement rocks in ikere ekiti, southwestern nigeria was carried out with the aim of determining the petrological characteristics and mineral composition of the various rock units dominating the study area in an attempt to unravel the pattern of deformation on the rocks. the method of investigation includes systematic geologic mapping to determine the underlying rock units, petrographic studies of the thin sections using light transmitting petrological microscope and; analysis and interpretation of the structural elements inherent in the rocks using rosette diagrams. seventeen (17) rock samples were collected on the field out of which ten (10) fresh rock samples were selected and prepared for thin section studies using standard procedures. geologic mapping of the studied area revealed that the rocks occured as plutons (older granite) while the charnockites and granites occur as pegmatitic intrusions into the older rock sequence. the granites and charnockites were extensively dissected by a network of intersecting or crosscutting quartzo-feldspathic stringers or veins/veinlets of various widths and dykes, which is an indication of the relevant post-tectonic deformation episodes and deuteric alteration in the evolutionary history of the rocks. also, the rocks are rich in quartz and feldspar with significant amounts of heavy minerals such as zircon, tantalite, tourmaline, heamatite, topaz and opaque minerals such as casiterite, chalcopyrite, sulphide and pyrrhotite. keywords: rock units, petrography, rosette diagram, photomicrographs, minerals, structures. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(3): 66-83 67 1. introduction the basement complex of southwestern nigeria lies within the reactivated part of the pan-african mobile belt between the west african and congo cratons [1, 2]. the basement complex is believed to have evolved as a result of at least four major orogenic cycles of deformation, metamorphism and remobilization corresponding to the liberian (2,700ma), eburnean (2000ma), kibaran (1,100ma) and the pan-african cycle (600ma). the first three cycles were characterized by intense deformation and isoclinal folding accompanied regional metamorphism, migmatization and extensive granitization and gneissification which produced syntectonic granites and homogeneous gneisses [3]. the lithologies in the studied area are highly weathered making it difficult to identify minerals and possible geologic structures that could be used to determine the geologic history as well as collection of fresh rock samples. several geoscientists have worked in the study area and similar areas, some of which are; rahaman [4], grant [5], anifowose and borode [6] amongst others giving account of the geology of the area. anifowose, et al. [7] noted that joints ranging from minor to larger ones are found in all the rock types. some of them are filled with quartz, feldspar, or a combination of both. they lie generally in the nw-se direction with minor variation in nne-ssw and ne-sw direction, while boesse and ocan [8] reported that the basement complex of south western nigeria has been affected by three phases of deformation namely d1, d2, d3. the first phase d1 produced tight to isoclinal folds, followed by the second phase d2 which is characterized by more open folds of variable styles and large vertical nne-ssn trending faults. okunlola and jimba [9] carried out petrographic and geochemical evaluation of pegmatite bodies around aramoko, ara and ijero area and concluded that majority of the samples are lepidolite sub class while some pegmatite bodies may have undergone mild post magmatic alteration, especially those outcropping around ijero area. caby and boesse [10] have also indicated the presence of nappes from shallow dips of foliations, shear zones, low angle thrusts and associated recumbent folds in the ife-ilesha area. oyinloye [11] also worked on the geology and geochemistry of banded and granite gneisses in ilesha area and concluded that the elements used to discriminate between tectonic settings for volcanic rocks are vulnerable to metamorphic alteration. however, this study attempts to carry out petrographic and mineralogical studies of the various rock units through thin sections, using the research petrological microscope under transmitted light and assess the impact of tectonic deformation in the study area. 2. location of the study area the studied area is situated within ikere and its environs. it is located between latitudes 7 0 00’n and 7º35n and longitudes 5º10’|e and 5º15’|e respectively covering a total area of 346.5km 2 . the mapped area is generally accessible with network of footpaths linking parts of the towns and to the outcrops. the settlement pattern in the area is nucleated and the major occupation of the inhabitants are farming and hunting (fig.1). 2.1. local geology of ikere ekiti ikereekiti and its environs is dominated by crystalline rocks such as migmatite-gneiss-quartzite complex, older granites, charnockites, fine-medium grained granite. there is close association between the charnockitic rocks and non-charnockitic granitic rocks due to their field relations as explained in the geology of the basement complex rocks of nigeria [12]; rahaman [13]; [14, 15] and hubbard [16]. the underlying rock units are as follows; 2.2. migmatite-gneiss-quartzite complex the migmatite-gneiss-quartzite complex is the oldest of the rock types in ikere-ekiti. it occupies about 80% of the study area and appears to be undifferentiated in pattern within the area. fig-1. map of ekiti showing the study area. asian review of environmental and earth sciences, 2014, 1(3): 66-83 68 it is characterized mostly by alternating light and dark coloured bands of minerals. the minerals are hornblende or biotite. according to olarewaju [17], quartz and plagioclase feldspar constitutes large percentage of minerals in the migmatite while the gneiss is medium grained and strongly foliated. the quartzite occurs as ridges and range from massive to schistose types. the schistocity is as a result of the presence of flaky minerals such micas and chlorite. they have simple mineralogy with quartz occurring as one of the essential minerals in addition to biotite, mymakite and microcline feldspar in the rock. 3. charnockites charnockites also abound in the study area. the geological map of the area produced by olarewaju [12] revealed that the charnockites occupy more than 70% of the land mass of ikere-ekiti. the prominent outcrops are found around ikereise road, comprehensive high school, afao, temidire ikereekiti (fig.2). the three main textural types of charnockites distinguished on the field conforms with olarewaju [18] classification and are coarse grained porphyritic charnockite, fine-medium grained charnockite and fine grained charnockite. most charnockite bodies in the basement complex of ikereekiti occur as low –lying outcrops in form of smooth elongated rounded boulders. fig-2. geological and cross-sectional map of the study area 3.1. method of study the method adopted for this research includes field examination of the rocks and structures; and laboratory preparation of the rocks for thin sections. grid sampling method with the aid of base map of the study area, and at a scale of 1:50,000 was adopted, coupled with the use of global positioning system (gps) for accurate geographical location of the various localities, and at a sampling density of one sample per 5 square km. seventeen (17) rock samples were collected from the studied area, which were clearly labeled and put into sample bag to avoid mix up. the general trend, attitudes of the rocks were observed and measured using compass clinometer. mega and micro structures such as folds, fractures, joints, veins and solution holes were also observed. all measurements were recorded in the field notebook and photographs of identified features on the outcrops such as joints, folds, fractures, xenoliths, solution cavities, tension gashes and foliations were taken. also, the orientations of structures such as veins, fractures and joints were plotted and represented in rosette diagrams. ten (10) fresh rock samples were selected from the bulk samples collected and were prepared for thin sectioning in other to identify the minerals embedded in the rocks using standard procedures of preparation. the slides were later mounted for microscopic studies using the research petrological microscope. 4. results table-1. field data s/n location gps reading rock type lithology texture structure 1 first baptist church ise road 7029ʹ53.55ʹʹn 5013ʹ50.39ʹʹe metamorphic rock migmatite coarse grained foliation , jointing fracture 2 iroke-ikere equity 7029ʹ54.68ʹʹ n 5014148.4511e igneous rock porphytic granite medium grained fracture joints 3 irokin, ise road 7029ʹ55.86ʹʹ n 5014ʹ50.38ʹʹe igneous rock charnockite medium grained joint fracture continue asian review of environmental and earth sciences, 2014, 1(3): 66-83 69 4 temidire area 7029ʹ55.08ʹʹ n 5014ʹ48.02ʹʹe igneous rock granite coarse grained fracture, cracks, joints 5 irokin, ikereekiti 7029ʹ56.46ʹʹ n 5014ʹ50.57ʹʹe igneous rock light-coloured granite fine grained veins, joints, cracks 6 keepers church araromi 7029ʹ59.03ʹʹ n 5014ʹ52.21ʹʹe igneous rock granite coarse grained fault, joints, xenoliths 7 araromi area 7029ʹ53.27ʹʹ n 5014ʹ51.95ʹʹe igneous rock charnockite fine grained joints, cleavages 8 state specialist hospital, iseequity 7029ꞌ42.50 ꞌꞌ n 5015ꞌ15.64 ꞌꞌ e igneous rock granite medium grained joint, fracture 9 oke-ikere 7029ʹ50.15ʹʹ n 5013ꞌ38.85 ꞌꞌ e igneous rock charnockite medium grained xenolith, dyke 10 oke-kajola 7030’18.395”n 5013’39.66 “ e igneous rock charnockite medium grained joints, xenolith, solution cavity 11 oke-igbo olobe 7030’18.30 “ n 5013’37.37 “ e igneous rock charnockite medium grained dyke, veins, joint 12 temidire afao 7030’14.97 “ n 5013’35.96 “ e igneous rock charnockite medium grained dyke, vein, joint 13 oke igbogbeyin 7030’8.47 “ n 5013’40.81”e igneous rock charnockite medium grained dyke, solution cavity , 14 ijoka area 7029’33.81” n 5013’41.55 “ e igneous rock porphytic granite coarse grained fracture, joints table-2. modal analysis of the rock samples minerals s1 s2 s3 s4 s5 s6 s7 s8 s9 s10 quartz 58 56 70 54 60 63 68 74 65 68 plagioclase 15 13 10 11 12 13 8 15 8 microcline 2 4 5 4 myrmekite 4 5 biotite 23 25 4 15 12 19 20 26 20 8 orthoclase 5 5 3 opaque 4 6 3 2 5 4 7 hornblende 2 4 11 2 table-3. description of samples s/n slide rock name location 1 s1 charnockite araromi 2 s2 charnockite temidire afao 3 s3 charnockite oke-kere 4 s4 pegmatite dyke oke-gbogbeyin 5 s5 porphyritic granite ijoka 6 s6 porphyritic granite araromi ise-road 7 s7 fined-grained granite state speacialist hospital 8 s8 coarsed-grained granite iroki-ise road 9 s9 medium-grained granite ise-road 10 s10 fine-grained granite keepers church araromi fig-3. chart showing (%) concentration of minerals in various samples. asian review of environmental and earth sciences, 2014, 1(3): 66-83 70 fig-4a. photomicrograph of medium grained granite slide under ppl x40 fig-4b. photomicrograph of medium grained granite slide under ppl x40 fig-5a. photomicrograph of fine grained granite slide under cnl x40 asian review of environmental and earth sciences, 2014, 1(3): 66-83 71 fig-5b. photomicrograph of fine grained granite slide under ppl x40 fig-7a. photomicrograph of porphyritic granite slide under cnl x40 fig-7b. photomicrograph of porphyritic granite slide under ppl x40 b asian review of environmental and earth sciences, 2014, 1(3): 66-83 72 fig-8a. photomicrograph of porphyritic granite slide under cnl x40 fig-8b. photomicrograph of porphyritic granite slide under ppl x40 fig-9a. photomicrograph of charnockite slide under cnl x40 asian review of environmental and earth sciences, 2014, 1(3): 66-83 73 fig-9b. photomicrograph of charnockite under ppl x40 fig-10a. photomicrograph of charnockite slide under cnl x40 fig-10b. photomicrograph of charnockite slide under ppl x40 asian review of environmental and earth sciences, 2014, 1(3): 66-83 74 fig-11a. photomicrograph of charnockite slide under cnl x40 fig-11b. photomicrograph of charnockite slide under (ppl) x40 fig-12a. photomicrograph of pegmatite slide under cnl x40 asian review of environmental and earth sciences, 2014, 1(3): 66-83 75 fig-12b. photomicrograph of pegmatite slide under ppl x40 fig-13a. photomicrograph of coarse grained granite under cnl x40 fig-13b. photomicrograph of coarse grained granite under ppl x40 asian review of environmental and earth sciences, 2014, 1(3): 66-83 76 fig-14. joint on charnockite at araromi, ikere fig-15a. quartz veinlet on charnockite at oke-ikere fig-15b. quartz vein on chrnockites at temidire, afao. asian review of environmental and earth sciences, 2014, 1(3): 66-83 77 fig-16a. pegmatite dyke on charnockite at ijoka fig-16b. pegmatite dyke on granitic rock at temidire. fig-17. cross-cutting relationship between a dyke and a vein at gbogeyin asian review of environmental and earth sciences, 2014, 1(3): 66-83 78 fig-18. solution cavity on granite at afao, ikere-ekiti fig-19. xenolith on granitic rock at afao, ikere ekiti fig-20. exfoliation on migmatites at keepers church, ise road, ikere asian review of environmental and earth sciences, 2014, 1(3): 66-83 79 fig-21. tension gashes on charnockite at ijoka fig-22. pinch and swell structure on charnockite at afao fig-23. mineral inclusions on charnockites at oke-ikere asian review of environmental and earth sciences, 2014, 1(3): 66-83 80 fig-24. ptygmatic fold on charnockitic rock at araromi. fig-25. rosette diagram of veins in the study area fig-26. rosette diagram of joints in the study area asian review of environmental and earth sciences, 2014, 1(3): 66-83 81 5. discussion the result of the field data acquired is presented in table.1. modal analysis of the different rock samples are shown in table.2, while table. 3 presents the sample locations and the % concentration of minerals in various samples. the photomicrographs of the thin section from the rocks are also shown (figs4-13), while the photographs of the various structural elements identified are presented (figs14-24) and the rosette plots of the veins and joints in the study area are shown (figs 25-26) respectively. 5.1. petrographic description of some prominent minerals in the slides the thin section was studied with the aid of petrological microscope and the slides were analyzed under plane polarized light and crossed nicols. 5.2. quartz (sio2) the mineral quartz is colourless under the plane-polarized light, with no pleochroism, and twinning. the habit is subhedral to anhedral. birefringence is also 1st order with extinction angle occurring at ~30°, 40° and 80°. habit is anhedral to subhedral. birefringence is 3rd order with extinction angle at angle ~37°, 30° and 32°. the hornblende is deep green, pleochroic prismatic crystals in thin section with 1st order birefringence. twining and extinction angle are totally absent. 5.3. biotite (mg,fe)3 alsi3o10(oh,f)2 biotite shows grey to brown coloration, with subhedral to anhedral habit and no twining. birefringence is 1st order and the mineral possess no extinction angles. biotite forms interstitial lamellae with brown pleochroism. commonly, an inner zone of deep green hornblende is surrounded by an outer biotite and quartz; this is shown in the digitized sketches of the slides in (plates 1-10). biotite has some inclusion of accessary minerals like apartite, zircon, rutile and mymrkite. 5.4. plagioclase feldspars (naaisi3o8-ca2ai2si2o8) the crystals of plagioclase are colourless in plane polarized light but exhibit first order grey colour when the polar is crossed. it can be distinguished from other types of feldspar because of its polysynthetic twining visible in the crystals. plagioclase occurs in some slides as phenocrysts. the more prevalent twining in the plagioclase is the albite with an extinction angle parallel to the cleavage direction. 5.5. hornblende (ca2(mg,fe)5(ai,si)8o22(oh)2 it appears as greenish black under plane polarized and shows pleochroism from green to brown. under plane polarized light, a few hornblende crystals showed the characteristics shape and two cleavages at 120º. in crossed polar, twinnings were seen in a few of the hornblende crystals and the highest interference colour seen, is a secondorder blue. 5.6. interpretation of the thin sections the petrographic examinations of the thin sections revealed the various mineral distribution such as quartz, biotite, hornblende, opaque, mymakite and feldspar (orthoclase, plagioclase and microcline). quartz and feldspar alone constitute up to 78% of the thin section. quartz is the most abundant and dominant mineral in all the slides and this indicated that the rocks are products of acidic magma crystallization. feldspar is second to quartz in abundance while ferro-magnesian and opaque minerals constitute the coloured minerals. this is illustrated in slide 1-10 (table 2) which depicts the sketches of the precambrian rocks around ikere-ekiti and their mineralogical components. 5.7. q-quartz, p-plagioclase, b-biotite, o-orthoclase, op-opaque, m-microcline, my-mrmykite, pplplane polarized light, cnl-cross nicol 5.7.1. rosette diagrams this is a diagram that shows the direction and minor images of joints and veins. rosette diagram are essential histograms into a circle to give a true angular plot. the data for plotting a rosette diagram was obtained from the field. rosette diagram is aimed at displaying the direction of the dominant tectonic force responsible for the deformation of the outcrops. the veins and joints data obtained on the field were used in plotting the rosette diagrams (figs 25&26) using grapher and rosetta sotwares. 5.7.2. interpretation of the rosette diagrams the structural feature observed includes veins and joints. these were measured and plotted on a rosette diagram and consequently used in the interpretation of the direction of the major tectonic forces or stresses that caused the deformation of the rock in the mapped area. the largest arc from the rosette diagram plotted represents the direction of the major tectonic force, so the rosette diagram of all the structures indicate a ne-sw direction and nw-se direction which is an indication of the direction of dominant tectonic forces prevailing in the studied area. 5.7.3. economic geology of the study area the economic potentials of the various lithologic units in the studied area can be used as dimension stones . granites of the studied area which is composed of red potassium-rich feldspar orthoclase feldspar, white and creamcolored plagioclase feldspar, dark and shiny flakes of biotite mica and gray irregular quartz grains of vitreous luster. the fact that the mineral grains are tightly interlocked gives it a greater strength and makes it a good material for buildings and sculptures as well as for construction purposes. the petrographic analysis has shown that quartz occur abundantly in the studied area and this makes quartz very useful in the silica industries, gemstone, wrist watch, floor asian review of environmental and earth sciences, 2014, 1(3): 66-83 82 tiles and many other compounds of commercial importance. also, the varying colours of charnokites as seen in the photomicrograph (fig.11a) explains its chances and usefulness as a dimension stones especially in the building of houses, tiles making, slabs and kitchen tops etc. 6. conclusion the petrological and mineralogical characteristics of the precambrian rocks in ikere ekiti have been carried out and the results presented in preceeding chapters. however, the magmatic origin of the precursor rocks of ikere-ekiti area is hereby established by the following lines of evidence: 1. the intrusive nature of the rocks, which is amply supported by the sharp contact relationship displayed by the various granitoid bodies with the country rocks; 2. the presence of a more coarser crystallinity in the core than at marginal areas of each of the granitoid bodies; 3. the incorporations of numerous xenolithic blocks that are often associated with slight displacements and/or rotations; 4. the developments of myrmekitic intergrowths at the plagioclase–alkali feldspar–quartz triple junctions, which also suggested the relevance of late magmatic/deuteric crystallization in the evolutionary history of the rocks. 5. the occurrence of microcline microperthite and complete absence of antiperthitic features in all the thin sections examined; 6. the parallel alignment of flaky and platy minerals in a manner that suggest control by magmatic flux. the presence of xenoliths in a rock body does not only indicate the magmatic character of the parent granitic rocks, but also give indication of the mode of emplacements of the rock. it was observed that magma could shoulder aside country-rocks or “roof‟ in making space for itself and in so doing is seen to be charged with xenoliths of the displaced country-rocks. xenoliths are actually evidence that a rock body was emplaced by the process of stopping. the modes of emplacement of magmatic rocks include shouldering aside and updoming of country rocks, a combination of cauldron subsidence and cauldron upheaval and stoping. the granite and charnockite of ikere-ekiti area are charged with numerous xenolithic lenses, rafts and blocks of the country rocks, therefore one of the mechanisms of emplacement of the parent granitic rocks may have been the process of stopping; and most likely, piecemeal stopping. the petrographic investigation shows that a distinct boundary can be drawn between the granite and charnockite in the studied area based on the textures and mineralogical composition. the texture of the pegmatite analyzed revealed a coarse grained type which is indicative of plutonics. it cooled very slowly close to the earth surface which resulted in its coarseness. also, the petrology and petrographic investigation of the study area revealed that quartz has the highest percentage modal composition in all the thin sections (table.2, fig.3). the rocks are characterized by the assemblages of quartz, biotite, hornblende, plagioclase, orthoclase, microcline, mymakite and opaque minerals. the structural features displayed on the rocks in the studied area (figs 14-24) are manifested on the charnockites and granitic rocks with structures such as joints, dykes, xenoliths, veins and veinlets seen on the outcrops mapped. the petrographic investigation indicates that the granites consists of minerals like quartz, biotite, plagioclase, and microcline, charnockite consists of minerals like quartz, plagioclase, and biotite while pegmatite consists of minerals like quartz, plagioclase, biotite, and microcline. it also showed that the rocks formed in the studied area were emplaced tectonically, based on the styles and magnitudes of structures detected and their disposition as seen in the rosette diagrams (figs 25&26). these structures are believed to be the product of the pan-african orogeny which affected the rocks in the studied area and are imprints of various stages of deformation in the area. field and petrographic characteristics confirm that the granitic parent rock and charnockites most likely had magmatic origin, and that one of the mechanisms of emplacement of the parent granitic rocks may have been the process of piecemeal stopping. both syn-tectonic and post-tectonic emplacements were probably relevant in the evolutionary history of the rock unit(s). it is hoped that further research work on the area, including geochemical, isotopic and geothermobarometric studies, will throw more light on the evolutionary history and tectonic setting of the rock unit(s). 6.1. recommendation the detailed petrographic and mineralogical investigation of the basement rocks in ikere-ekiti, south-western nigeria has shown that the study area belongs to the precambrian basement complex of nigeria. in view of the research conducted in the studied area, the following recommendations are proposed to improve on the present study such as detailed geological mapping should be carried out to discover other secondary structures of importance which could elucidate further the manner and styles of deformation in the study area. further research should be carried out in ikere-ekiti in other to delineate the impact of the various deformational episodes on geodesy and environment. 6.2. acknowledgement i hereby acknowledge the contributions and technical assistance from kenneth chidiebere nwosu during field work and data collection stages of this work. references [1] w. o. kennedy, "the structural differentiation of africa in the pan african thermotectonic episode," university of leeds, research institute of african geology, 8th annual rep, 1965. [2] t. n. clifford, the structural framework of africa. in clifford, t.n and gass, i.g (eds). african magmatism and tectonics. edinburg: oliver & boyd, 1970. [3] s. i. abaa, "the structure and petrography of alkaline rocks of the mada younger granite complex, nigeria," journal of african earth science, vol. 3, pp. 107-113, 1983. [4] m. a. rahaman, recent advances in the study of the basement complex of nigeria. in: oluyide p.o, et al., (eds). precambrian geology of nigeria. kaduna: geological survey of nigeria publication, 1988. [5] n. k. grant, "geochronology of precambrian basement rocks from ibadan, southwestern nigeria," earth and planetary science letters, vol. 10, pp. 29-38, 1970. [6] a. y. b. anifowose and a. m. borode, "photogeological study of the fold structure in okemesi area, southwestern nigeria," journal of mining and geology, vol. 43, pp. 125-130, 2007. asian review of environmental and earth sciences, 2014, 1(3): 66-83 83 [7] a. y. b. anifowose, i. b. odeyemi, and a. m. borode, "the tectonic significance of the ifewara-zungeru megalineament in nigeria," in proceedings of the 1st international workshop on geodesy and geodynamics . centre for geodesy and geodynamics, toro, bauchi state nigeria, february 9-11, 2005, 2006. [8] s. boesse and o. ocan, "geology and evolution of the ife-ilesha schist belt, southwestern nigeria," in benin-nigeria geotraverse. international meeting on the proterozoic geology and tectonics of high grade terrain. igcp, 1992. [9] o. a. okunlola and s. jimba, "compositional trends in relation to ta-nb mineralization in precambrian pegmatites of aramoko-araijero area, southwestern nigeria," journal of mining and geology, vol. 42, pp. 113-126, 2006. [10] r. caby and m. boesse, "pan african nappe system in southwest nigeria: the ife-ilesha schist belt," journal of african earth sciences, vol. 33, pp. 211-225, 2001. [11] a. o. oyinloye, "geology, geochemistry and origin of the banded and granite gneisses in the basement complex of ilesha area, southwestern nigeria," nigerian journal of african earth sciences, vol. 26, pp. 633-641, 1998. [12] v. o. olarewaju, ree in the charnockitic and associated granitic rocks of ado-ekiti-akure, southwestern nigeria. in: oluyide p.o. et al (eds). precambrian geology of nigeria. kaduna: geological survey of nigeria publications, 1988. [13] m. a. rahaman, review of the basement geology of southwestern nigeria. in: kogbe, c.a. (ed). geology of nigeria. lagos: elizabethan publishing company, 1976. [14] p. g. cooray, notes on the charnockites of the ado-ekiti area, western state, nigeria. in: african geology ibadan. (eds). dessauvage and whiteman, geology department. nigeria: university of ibadan, 1972. [15] p. g. cooray, "classification of charnockitic rocks of nigeria," journal of mining and geology, vol. 14, pp. 1-6, 1977. [16] f. h. hubbard, "the association charnockite –older granite in southwestern nigeria," journal of mining and geology, vol. 3, pp. 2532, 1968. [17] v. o. olarewaju, "geochemistry of the charnockite and granitic rocks of the basement complex around ado ekiti, southwestern nigeria," unpublished ph.d thesis, university of london, 1981. [18] v. o. olarewaju, the charnockitic intrusive of nigeria. in oshi (ed). the basement complex of nigeria & its mineral resources (a tribute to prof. m.a.o rahaman). ibadan: akin jinad & co, 2006. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences vol. 4, no. 1, 36-45, 2017 issn(e) 2313-8173/ issn(p)2518-0134 doi: 10.20448/journal.506.2017.41.36.45 36 impacts of treated wastewater on the surface water and groundwater quality: a case study in north east gaborone, botswana tshepo k1 tafesse nt2  chaoka rt3 alemaw bf4 laletsang k5 ( corresponding author) 1,2,3,4,5department of geology, university of botswana, gaborone, botswana abstract this study was conducted in the notwane catchment where the capital city of botswana, gaborone is located. botswana having unreliable rainfalls and gaborone having shortage supply of water for drinking, this study was initiated with the aim of investigating alternative sources in this part of the country. even though treated wastewater is available in the studied area, this water is not much utilized at present. the objective of the research is to investigate the impact of treated wastewater on the quality of surface water and groundwater in the north east of gaborone, so that this water can be utilized for different purposes including as a source for groundwater recharge. the research area is located near gaborone in south east district within notwane catchment, which is a tributary to the limpopo river, having an area of about 3 000 sq. kms. for this purpose forty-one surface water samples, one treated wastewater sample and fifteen groundwater samples were collected from different parts of the study area. all the water samples were analysed for major cations (ca2+, mg2+, k+, na+ and li+), anions (hco3 -, cl-, so4 2-, no3 -, f-, po4 3and co3 2) and some trace elements (as, ba, cd, co, cr, cu, fe, mn, pb, ni and zn). for all the water samples alkalinity and hardness were determined using aquachem software. simple descriptive statistical method was utilized for the analyses of the water chemistry data. aquachem and suffer software’s were also used for analyses the water chemistry data. the surface water range from slightly alkaline to very hard whereas the treated wastewater is slightly alkaline to hard and groundwater is slightly acidic to very hard.in all the waters, surface water, treated wastewater and groundwater based on the mean values of the chemical parameters, the cations were in the order of abundance as na+> ca2+> mg2+> k+> li+. surface water anions were in the order of abundance as hco3 >cl> so4 2> no3 > po4 3> f>co3 2-, treated wastewater as hco3 >cl> no3 > so4 2> po4 3> f> co3 2while in the groundwater the anions reveal order of abundance as cl> hco3 > so4 2> no3 > co3 2 > f> po4 3-. based on the mean values of the chemical parameters in the surface water, the analyzed trace elements were in the order of abundance as ni > fe >pb> ba > zn >mn> cd > as > co > cr > cu, in the treated water ni > ba > zn >pb> fe > cd >mn> as > co > cr and cu having equal concentration (0 mg/l) while in the groundwater the analyzed trace element reveal order of abundance as ni >pb> ba >mn> zn > fe > cd > as > cu > co > cr. the results of the hydrochemical analyses of all the waters disclose that the groundwater chemistry is highly controlled by rock-water interaction and anthropogenic activities in the catchment than the chemistry of surface water and treated wastewater. the analysed cations for surface water and treated wastewater satisfy the standard of both who and botswana bureau of standards whereas in the groundwater the cations are highly above the recommended limits of the standards set by both who and botswana bureau of standards with the exception of lithium and potassium. the analysed anions for surface water and treated wastewater fulfil the standard of both who and botswana bureau of standards whereas in the groundwater the concentration of cl and no3 were above the standards set by both who and botswana bureau of standards. in the analysed trace elements for all the waters, almost all samples met the trace element standards set by both who and botswana bureau of standards with the exception of nickel and lead in surface water, treated wastewater and groundwater. the overall chemical analyses of the water chemistry revealed that treated wastewater quality does not have any significant harm to both surface and groundwater quality; therefore it can be used as a source of recharge to the aquifers in the catchment. keywords: botswana, groundwater quality, rock-water interaction, wastewater, water type. https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tshepo k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=chaoka rt https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k asian review of environmental and earth sciences, 2017, 4(1): 36-45 37 citation | tshepo k; tafesse nt; chaoka rt; alemaw bf; laletsang k (2017). impacts of treated wastewater on the surface water and groundwater quality: a case study in north east gaborone, botswana. asian review of environmental and earth sciences, 4(1): 36-45. history: received: 4 october 2017 revised: 6 december 2017 accepted: 11 december 2017 published: 14 december 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: the financial support from ord office of the university of botswana and the department of geology are highly acknowledged. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 37 2. methodology ..................................................................................................................................................................................... 39 3. results and discussions .................................................................................................................................................................. 40 4. conclusions ....................................................................................................................................................................................... 44 references .............................................................................................................................................................................................. 44 1. introduction 1.1. general sewage water refers to the water that has biological, physical and chemical contaminants which is generated by resident, institutional and commercial industrial establishment. water is said to be polluted when it contains enough impurities to make it unfit for a particular use, such as drinking, swimming, or fishing. sewage water treatment refers to the process of reducing the contaminants to acceptable levels to make the water safe for discharge back into the environment and reuse for irrigation, washing, construction and many more. it includes the physical, biological and chemical processes to remove physical chemical and biological contaminants. the general sewage (wastewater) treatment involves four stages, screening, primary, secondary and tertiary treatment. water quality standards are designed to provide us with understanding the critical importance of adequate supplies of clean, available fresh water for the environment, the country’s economy and the quality of life. botswana bureau of standards (bobs) has established upper limits and ranges for chemical levels allowable in drinking, irrigation and livestock water. most of these levels allow a sufficient margin of safety. it must be noted that acceptable contaminant levels vary widely among individuals, for example high sodium which may be harmless for many people can be dangerous for elderly, hypertensive persons, pregnant women and people having difficulty in excreting sodium. botswana is experiencing shortage of water supply due to prolonged dry seasons and declined rainfall amounts.in support of that the annual has decreased and it was found out that rainfall quantiles with a 10-year recurrence interval will decrease by 2–17% [1]. according to botswana central statistics office [2] water from dams and rivers contribute about one third to national water consumption. an increasingly large proportion of the population which resides in the urban areas as a result of urban migration is supplied by water from the dams. gaborone dam supplies water to two towns: gaborone and lobatse. the dam is located along notwane river and has a storage capacity of 141.1 million cubic meters. its water is supplemented by bokaa dam located along the metsimotlhabe river in kgatleng district. according botswana central statistics office [2] the population of gaborone has increased from 186 007 in year 2001 to 231 592 in 2011 and forecasted an increase to 259 300 in 2016 which directly also indicate an increment in the water demand. statistics also indicated that gaborone uses about 2 824 291* 103 litter of water monthly. the high water demand in southern parts of botswana prompted the operation of north south carrier (nsc) pipeline that supplies water from dikgathong dam in the northern part of botswana, to gaborone and surroundings in the southern part of the country. furthermore botswana bureau of standards [3] revealed that there was high reliance on the north south carrier (nsc) that seemed to operate at maximum capacity. water transferred through the nsc between 2012/13 and 2013/14 has increased and amounts to 23.6 and 36.1 million cubic meter, respectively, in the given period and that has brought water conservation strategies and reuse into consideration. treated wastewater became an alternative and reduced the reliance on fresh water for purposes such as irrigation and construction. in the study area the wastewater treatment plant is located on latitude 24.610s and longitude 25.960e in glen valley (gaborone north-east), downstream of gaborone dam. the first phase of a treatment works has a capacity of 40,000 m3/day and operating at an average of 20 000 m3/day. the second face of the plant has a capacity of 50 000 m3/day and has not started operating which totals to 90000 m3/day if the plant operates at 100%. the treatment plant is expected to treat all the wastewater generated in the greater gaborone and it also has an emergency overflow sewage-retaining dam. after treatment the water is pumped to maturation ponds, the ponds allow the water for further treatment as the water stays there for 15 days before it can be discharged into game park. the water from the maturation converges at the pump station where it pumped to existing reservoirs where it is utilised for various purposes such as irrigation and construction. the water in the ponds is also a source of aquatic life, birds, other animals and beautiful reeds. furthermore, the area near the ponds slopes to the notwane river, which is the main stream in the catchment. water resources of the study area are dominated by the notwane river that flow downstream of gaborone dam and treated wastewater from wastewater treatment plant, which also flows to the notwane river. the impacts of treated wastewater in gaborone are generally based on wastewater movement on the surface and underground. the greatest threats posed to water resources arise from contamination by bacteria, nitrates, metals, trace quantities of toxic material and salts. seepage overflow into drinking water sources can cause diseases from ingestion of micro-organisms and heavy metals. according to emongor and ramolemana [4] there are physical and chemical soil related problems associated with using secondary treated sewage water in horticultural http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2017, 4(1): 36-45 38 production. the physical problems include clogging, soil drainage and aeration while the chemical problems include soil salinity, sodicity and accumulation of heavy metals. groundwater contamination is a concern in botswana two well fields, the ramotswa and the mochudi well fields, which are located in the south-eastern part of botswana. the well fields are no longer used for water supply sources for drinking purposes as a result of bacterial and nitrate pollutions caused by poor disposal sanitary waste [5]. as abstraction rates increases in the wells of these well fields, the cone of depression increases and water would be drawn from far and often interferes with many pollutions sources. 1.2. objectives the major objective of this research was to investigate the impact of treated wastewater on the quality of surface water and groundwater in the north-east of gaborone. the following were the specific objectives the research. • to investigate the major ions and trace element composition of the surface water: • to investigate the major ions and trace element composition of the groundwater: • to investigate the major ions and trace element composition of the treated wastewater: • to investigate the impact of the treated wastewater on the groundwater quality: • to investigate the suitability of the treated wastewater for drinking purpose: and, • to investigate the suitability of the treated wastewater as a recharge source for the aquifers in the gaborone area. 1.3. description of the study area the research area is located near gaborone in south east district bounded between 23.7o s and 24.7o s and 25.8oe and 27.0oe within notwane catchment which has a total area of about 18 053 square kilometres. it is bound to the southwest by the southern district, to the northwest by the kweneng district and in the north by the kgatleng district. the entire eastern part of the district borders with south africa. hydrologically, the study area is along the notwane river downstream of the gaborone dam about 3 000 square kilometres to mmakgopong village. the notwane river is a tributary of limpopo river.in general the area is undulating with slopes from south-east (upstream) to north-east (downstream). the notwane river drains north east into the limpopo river and has tributaries metsimotlhaba, thagale and monametsanarivers.the climate of the study area is generally semi-arid with an annual average rainfall varying between 250-500 mm, unreliable, unevenly distributed and highly variable from year to year and together with a very high amount of evaporation which is of the order of about 2000 mm/annum.the study is area occupied with the city of gaborone, oodi, morwa, malotwane, mmakgopong villages and other small settlements. there are several economic activities in and around the city leading to major and small-scale industrial, commercial and institutional developments figure 1 and 2 shows the location of the study area, which start from the south east (gaborone city) district into kgatleng district and the study area boundary in notwane catchment. figure-1.location map of study area. source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. asian review of environmental and earth sciences, 2017, 4(1): 36-45 39 figure-2. study area in notwane catchment. source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. figure-3. sample location source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. 2. methodology 2.1. general in order to achieve the mentioned objective of the research primary and secondary data were collected at different times of the research period. primary data were collected both in the field and in the laboratory using different techniques. secondary data such as location of boreholes, geological reports and maps, rainfall records, soils and land use were collected from different office in gaborone. surface water and groundwater samples were collected from february to april in 2016 from different parts of the study area (figures 3). physico-chemical parameters such as ph, total dissolved solids (tds), electrical conductivity (ec) and temperature were measured for all the samples using portable digital multi parameter analyser in situ immediately after sampling. all the samples were analysed for major cations, anions trace elements. 2.2. data collection forty-one surface water samples were collected starting from the gaborone dam downstream along the river to the catchment common outlet at mmakgopong village: twenty six surface water samples were collected at different location from notwane river starting from the upstream side of the study area (after the gaborone dam) to the outlet (figure 3), nine surface water samples were also collected from the tributaries of the notwane river before their respective junction point and six samples were collected from dams and small ponds inside the study area. surface water sampling was done following the flow direction of the surface waters. one sample was collected from the pond that is located at mouth of the last treatment plant as a representative to the treated wastewater. fifteen groundwater samples were collected from the boreholes that are found in the area close to the notwane river and far away from the influence of the river (figure 3). the water samples were collected in one litre polyethylene terephthalate bottles. prior to sampling the bottles were rinsed with samples to be collected. all the sampling points were located with the help of gps. 2.3. data analysis the water samples were analysed for major cations (ca2+, mg2+,k+, na+and li+), anions (hco3 -, cl-, so4 2-, no3 -, f-, po4 3and co3 2) and trace elements. the trace elements that were analysed were arsenic (as), barium (ba), cadmium (cd), cobalt (co), chromium (cr), copper (cu), iron (fe), manganese (mn), lead (pb), nickel (ni) and zinc (zn). all the samples were filtered using 45µm membrane before analysis. the major cations and all the trace elements were analysed in the geochemistry laboratory of the department of geology, university of botswana using inductively coupled plasma mass spectrometry or icp-ms. the anions were analysed in the water quality laboratory of the department of water affairs. for all the water samples alkalinity and hardness were determined using aquachem software. asian review of environmental and earth sciences, 2017, 4(1): 36-45 40 the analytical precisions for the measurements of ions were determined by calculating the ionic balance error using the following formula. where, e.n (%) = 100* anions) sum cations (sum anions) sum cations (sum         all the measurements are in milli equivalents per litre. it is found that the majority of the analyses were within the acceptable range. simple descriptive statistical method was utilized for the analyses of the water chemistry data. aquachem and suffer software’s were also used for analyses the water chemistry data. aquachem software is a fully integrated statistical package developed specifically for graphical and numerical analyses of aqueous geochemical data sets. piper diagram and radial plots were prepared using this software for graphical presentation of the results and compare water quality data in the area. suffer software was used to show contour map of distribution of elements in groundwater by kriging method. gibb’s diagram was also used to see the relationship of water composition and aquifer lithological characteristics. the suitability of the waters of the studied area for drinking purpose was evaluated with respect to the standard set by both the world health organisation [6] and the botswana bureau of standard [7]. 3. results and discussions 3.1. physico-chemical parameters the surface water is slightly alkaline to alkaline, fresh, and soft to very hard whereas the treated waste water is slightly alkaline, fresh and hard. groundwater is slightly acidic to alkaline, fresh to saline and soft to very hard. with the exception of the three samples in the groundwater, both groundwater and surface water of the study area show a high ph value as compared to the treated wastewater. high ph values could be associated with pollution emanated from the different activities of the society in the villages that are drained by the both surface water and groundwater of the catchment. a discharge of used water by the users that contains detergents and soap-based products can cause the water to become too basic. this high ph can causes a bitter taste, water pipes and water-using appliances become encrusted with deposits, and it also depresses the effectiveness of the disinfection of chlorine, thereby causing the need for additional chlorine when ph is high. figure-4. surface water ph source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. figure-5. groundwater ph. source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. asian review of environmental and earth sciences, 2017, 4(1): 36-45 41 among the examined water samples, the highest value of both ec and tds were measured in the groundwater of the catchment. 67 and 60 percent of the total groundwater samples have an ec of greater than 1000 µs/cm and a tds greater than 1000 ppm, respectively. the minimum ec and tds values are measured in boreholes z1 and z5, which are located in the downstream side far from the river influences. the highest value of ec and tds was measured in borehole z10, which is located in mochudi village. in general boreholes close to the river bank of notwane river (z4, z7, z11, z14 and z15) and upstream side (oodi and mochudi villages) have high values of dissolved solids and electric conductivity values. these might be due to human activities associated with those major villages that have high number of population found in this part of the catchment. this significant high value of ec and tds of the groundwater as compared to the surface water and treated water suggesting that the groundwater is not only an infiltration of the local precipitation and treated water rather have an additional source (regional ) besides to that of surface water and the treated water. uncontrolled sewage, pit latrines, fertilizer, pesticides application in farms and water rock interaction could also be contributed to the rise of these chemical parameters in the groundwater. the table below shows the general water classification scale based on tds [8]. table-1. groundwater classification category total dissolved solids (mg/l) fresh water 0-1000 brackish water 1000-10 000 saline water 10 000-100 000 brine water more than 100 000 both the surface water and treated water alkalinity is a typical of fresh water alkalinity, which is in the range of 20 to 200 mg/l of caco3. generally both waters are not poorly buffered, and are not also very susceptible to changes in ph from natural and human-caused sources. with the exception of one sample, the alkalinity of the groundwater ranges from 43.31 to 474.06 mg/l of caco3 with mean value of 206.36 mg/l of caco3. this range of alkalinity is high as compared to the surface water and treated water. groundwater sample z7 has the highest alkalinity of 1208.53 mg/l. the borehole from which sample z7 was collected is located close to the river bank of notwane river in the middle of study area (after the river has collected surface water from bokaa, pilane and mochudi villages). the wastewater from the houses of the major villages or household wastes could be source of this high alkalinity in the groundwater. the wastewater from our houses contains carbonate and bicarbonate from the cleaning agents and food residue that we put down our drains. the cause to high alkalinity of the groundwater could also be the cause to this high hardness in the groundwater. 3.2. water type fifteen water types are recognized in the surface water of the studied area. among them the dominants are nahco3-cl, na-mg-hco3-cl and ca-mg-na-hco3 (table 1).the treated wastewater is na-mg-hco3-cl type. thirteen types of groundwater are identified in the study area. among those water types the dominant ones are mg-ca-na-cl and mg-cl-hco3. in all the dominant water types of surface water and groundwater including treated wastewater the chemical analyses indicated the existence of cl as major constituent in these water, and all these are found in the upstream side and middle of the catchment, suggesting a possible link with the anthropogenic activities associated with development activities in the upstream side of the catchment. 3.3. major ions in all the waters, surface water, treated wastewater and groundwater based on the mean values of the chemical parameters, the cations were in the order of abundance as na+ > ca2+> mg2+ > k+> li+. based on the mean values of the chemical parameters in the surface water the anions were in the order of abundance as hco3 >cl> so4 2> no3 > po4 3> f> co3 2-, in the treated water hco3 > cl> no3 > so4 2> po4 3> f> co3 2while in the groundwater the anions reveal order of abundance as cl> hco3 > so4 2> no3 > co3 2 > f> po4 3-. the figures 6 and 7 below show the piper diagram for surface water and treated wastewater and groundwater, respectively. fig. 6 shows that in the anion triangle all samples are concentrated towards hco3 indicating the dominancy of this species in the surface water and treated wastewater whereas fig. 7 shows that dominant anion in the groundwater is cl. as for the cation in the surface water and treated wastewater, samples are clustered towards calcium and a combination of sodium and potassium, with a dominancy of na + k (fig. 6). the diamond plot shows that the majority of the surface water samples and a treated wastewater sample lie below 40% of ca and mg. as for the cation in the groundwater, samples are clustered towards a combination of sodium and potassium and magnesium end, with dominant number of samples toward the combination of sodium and potassium (fig. 7). asian review of environmental and earth sciences, 2017, 4(1): 36-45 42 table-2. water types surface water groundwater treated wastewater sample id water type sample id water type sample id water type sw1 na-mg-co3 z1 mg-na-hco3 sw36 na-mg-hco3-cl sw2 na-hco3-co3 z2 na-mg-cl sw3 na-hco3 z3 na-cl-hco3 sw4 mg-na-ca-hco3 z4 mg-na-ca-cl sw5 ca-na-hco3 z5 na-mg-hco3-cl sw6 na-hco3 z6 na-ca-mg-so4-cl-hco3 sw7 mg-na-ca-hco3 z7 mg-hco3 sw8 ca-mg-na-hco3 z8 ca-mg-hco3-no3 sw9 mg-na-ca-hco3 z9 mg-na-hco3-cl sw10 na-mg-hco3-cl z10 mg-ca-na-cl sw11 na-mg-ca-hco3 z11 mg-ca-na-cl sw12 mg-ca-na-hco3 z12 mg-cl-hco3 sw13 na-hco3-cl z13 na-mg-cl-hco3 sw14 na-mg-hco3-cl z14 mg-cl-hco3 sw15 na-hco3-cl z15 mg-ca-cl sw16 na-mg-hco3-cl sw17 na-hco3-cl sw18 na-hco3-cl sw19 na-hco3-cl sw20 na-hco3-cl sw21 na-hco3-cl sw22 ca-mg-na-hco3 sw23 na-hco3-cl sw24 na-mg-ca-hco3-cl sw25 na-mg-hco3-cl sw26 na-hco3-cl-so4 sw27 na-mg-hco3-cl sw28 na-hco3-cl sw29 na-mg-ca-hco3-cl sw30 na-mg-hco3-cl sw31 na-mg-ca-hco3 sw32 ca-mg-hco3 sw33 mg-ca-hco3 sw34 mg-ca-na-hco3 sw35 ca-mg-hco3-cl sw37 ca-mg-hco3 sw38 ca-mg-hco3-cl sw39 na-hco3-cl sw40 ca-mg-na-hco3 sw41 ca-mg-na-hco3 sw42 ca-mg-hco3 source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. figure-6. surface water piper plot source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. asian review of environmental and earth sciences, 2017, 4(1): 36-45 43 figure-7. groundwater piper plot source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. in the treated wastewater, the concentration of the major cations with the exception of li have a concentration greater than the concentration in the surface water , whereas in the groundwater the concentrations of all the major cations are greater than the concentrations of the major cations in both the surface and treated waste water. in the treated wastewater, the concentration of the analyzed major anions with the exception of fluorine and carbonate, have a concentrations greater than surface water whereas in the groundwater, the concentration of all the analyzed major anions are greater than the concentrations both the surface and treated wastewater, with the exception of carbonate and phosphate. in the groundwater, the measured concentration of cl(1322.5 mg/l) and no3 (60.67 mg/l)is much greater than the measured concentrations of these ions both in the surface and treated wastewater whereas the measured concentration of po4 3in the groundwater is significantly less than the measured concentration of po4 3in both surface water and treated wastewater. the highest measured concentration of po4 3(9.53 mg/l) is in the treated wastewater. uncontrolled human wastes or sewage are the possible sources of cland no3 ions in the groundwater. the presence of high concentration of phosphate ion in the treated wastewater and absence of more or less corresponding concentration in both the surface water and groundwater implies that the treated water is not the source for pollution to both surface and groundwater in the catchment. in the analysed groundwater of the catchment the concentrations of all the analyzed major cations and anions (with the exception of carbonate and phosphate) are greater than the concentrations of the analyzed major cations and anions in both the surface water and treated waste water suggesting that the overall chemistry of the groundwater is not only controlled by the chemistry of the original precipitation and the chemistry of the treated wastewater rather by the water-rock interaction processes while the groundwater transmitted and stored in the different rock formations of the catchment . supporting this idea the gibbs diagram below (figure 8) shows the controlling mechanism of groundwater quality is rock weathering dominance. fourteen samples out of fifteen are within the rock weathering dominance, while one sample collected in borehole z7 indicated evaporation dominance. in addition to that figure 9 (dominant cation vs dominant anions) also shows that silicate weathering is the major process that control the rock-water interaction processes in the catchment. most of the boreholes are drilled in the igneous rocks formation found in the upstream side of the catchment. figure-8. gibbs diagram for groundwater. source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. asian review of environmental and earth sciences, 2017, 4(1): 36-45 44 figure-9. groundwater carbonates weathering vs silicate weathering. source: tshepo k., m.sc. thesis, university of botswana, gaborone, botswana, 2017. 3.4. trace elements all the analyzed trace elements in the treated wastewater, with the exception of cadmium and cobalt, have a concentration less than the concentration in the groundwater of the catchment. in the treated wastewater, with the exception of ni and zn, all the remaining analyzed trace elements have a concentration less than concentration in the surface water. therefore in the treated wastewater the concentration of zinc is insignificant to be a pollutant. however, the concentration of ni is not avoidable to be a pollutant toward the surface water and groundwater of the catchment: though it is not the only source. the different mineralogical compositions of the rocks of the studied area have also their own contribution. 4. conclusions in all the water, surface water, treated wastewater and groundwater, the dominant cations and anions are sodium, calcium, bicarbonate and chlorine. in all the waters the dominant cation is na+. in all the waters, surface water, treated wastewater and groundwater, based on the mean values of the chemical parameters, the cations were in the order of abundance as na+> ca2+> mg2+> k+> li+. in both the surface water and treated wastewater the dominant anion is hco3whereas in groundwater is cl-. based on the mean values of the chemical parameters, in the surface water the anions were in the order of abundance as hco3 > cl> so4 2> no3 > po4 3> f>co3 2-, in the treated water hco3 > cl> no3 > so4 2> po4 3> f>co3 2while in the groundwater the anions reveal order of abundance as cl> hco3 > so4 2> no3 > co3 2 > f>po4 3-. among the analyzed trace elements, the dominant in all the water, surface water, treated wastewater and groundwater is nickel. based on the mean values of the chemical parameters, the order of abundance of trace elements in the surface water was ni > fe > pb > ba > zn > mn > cd > as > co > cr > cu, in the treated wastewater ni > ba > zn >pb> fe > cd > mn > as > co > cr and cu having equal concentration (0 mg/l) while in the groundwater the analyzed trace element reveal order of abundance as ni > pb > ba > mn > zn > fe > cd > as > cu > co > cr. the overall chemical analyses of the water chemistry revealed that the hydrochemistry of the groundwater in the study area is not only controlled by the chemistry of the original precipitation, chemistry of surface water and chemistry of treated wastewater but also dominantly by the water-rock interaction processes while the groundwater transmitted and stored in the different rock formations of the catchment and anthropogenic activities in the area. the analysed cations for surface water and treated wastewater satisfy the standard of both who and botswana bureau of standards whereas in the groundwater the cations are highly above the recommended limits of the standards set by both who and botswana bureau of standards with the exception of potassium. the tested anions for surface water and treated wastewater satisfy the standard of both who and botswana bureau of standards whereas in the groundwater the concentration of cl and no3 were above the standards set by both who andbotswana bureau of standards. in the analysed trace elements for all the waters, almost all samples met the trace element standards set by both who andbotswana bureau of standards with the exception of nickel and lead in surface water, treated wastewater and groundwater. generally, on the basis of the overall chemical analyses of the water chemistry, the study revealed that treated wastewater quality does not have any significant harm to both surface and groundwater quality; therefore it can be used as a source of recharge to the aquifers in the catchment. references [1] b. f. alemaw, e. m. shemang, and t. r. chaoka, "assessment of groundwater pollution vulnerability and modelling of the kanye wellfield in se botswana—a gis approach," physics and chemistry of the earth, parts a/b/c, vol. 29, pp. 1125-1128, 2004. view at google scholar | view at publisher [2] botswana central statistics office, "botswana water statistics." retrieved from http://www1.eis.gov.bw/eis/reports/botswana%20water_statistics%20report.pdf, 2009. [3] botswana bureau of standards (bobs)," drinking water specification," gaborone, 2nd ed. vol. 32, 2009. https://scholar.google.com/scholar?hl=en&q=assessment%20of%20groundwater%20pollution%20vulnerability%20and%20modelling%20of%20the%20kanye%20wellfield%20in%20se%20botswana—a%20gis%20approach https://scholar.google.com/scholar?hl=en&q=assessment%20of%20groundwater%20pollution%20vulnerability%20and%20modelling%20of%20the%20kanye%20wellfield%20in%20se%20botswana—a%20gis%20approach http://dx.doi.org/10.1016/j.pce.2004.09.026 http://www1.eis.gov.bw/eis/reports/botswana%20water_statistics%20report.pdf, asian review of environmental and earth sciences, 2017, 4(1): 36-45 45 [4] v. emongor and g. ramolemana, "treated sewage effluent (water) potential to be used for horticultural production in botswana," physics and chemistry of the earth, parts a/b/c, vol. 29, pp. 1101-1108, 2004. view at google scholar | view at publisher [5] r. a. freeze and j. a. cherry, groundwater (1979). englewood cliffs: printice-hall inc, 1979. [6] ministry of minerals energy water resources, botswana water accounting report 2015. gaborone: botswana government, 2015. [7] b. p. parida and d. b. moalafhi, "regional rainfall frequency analysis for botswana using l-moments and radial basis function network," physics and chemistry of the earth, parts a/b/c, vol. 33, pp. 614-620, 2008. view at google scholar | view at publisher [8] world health organization, guidelines for drinking-water quality. new york: iwa publishing, 2004. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=treated%20sewage%20effluent%20(water)%20potential%20to%20be%20used%20for%20horticultural%20production%20in%20botswana http://dx.doi.org/10.1016/j.pce.2004.08.003 https://scholar.google.com/scholar?hl=en&q=regional%20rainfall%20frequency%20analysis%20for%20botswana%20using%20l-moments%20and%20radial%20basis%20function%20network http://dx.doi.org/10.1016/j.pce.2008.06.011 9 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 9-15, 2019 issn (e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.9.15 © 2019 by the authors; licensee asian online journal publishing group spatial analyses of suitable solid waste dumping sites in damaturu, yobe state nigeria karagama kolo geidam1 alhaji mustapha isa2 ( corresponding author) 1department of general studies mai idris alooma polytechnic, geidam yobe state, nigeria 2department of civil engineering mai idris alooma polytechnic, geidam yobe state, nigeria abstract the generation and disposal of solid waste is a serious problem in urban areas especially in developing countries. this is because of high generation rates, insufficient budget and machinery for solid waste management, inappropriate techniques and few or non-existent suitable dumping sites. the main objective of this study is to propose suitable areas for solid waste dumping in damaturu town, which are environmentally suitable and economically viable. the main data used for this study were landsat 8 oli tirs image with a spatial resolution of 30m; digital elevation model (dem) with 30m spatial resolution, and ground control point (gcp) collected with a handheld global positioning system (gps). the maps were prepared by overlay and suitability analysis was carried out using geographic information system (gis), remote sensing techniques and multi criteria analysis methods. the final suitability map was produced by overlay analyses in arcmap and levelled as high, moderate, less suitable, and unsuitable regions. the results indicate that 65% of the study area is unsuitable for solid waste dumping; 1.3% less suitable; 21.8% moderately suitable; and 11.9% most suitable. the potential most suitable areas for solid waste dumping sites fall on southern, south eastern and south western parts of the town where there are least environmental and health risks. the gis and remote sensing techniques are important tools for solid waste site selection. hence, the capacity to use gis and remote sensing technology for the effective identification of suitable solid waste dumping site will minimize the environmental risk and human health problems. keywords: urbanization, solid waste, dumping sites, geographic information system, remote sensing, global positioning system, spatial, digital elevation model. citation | karagama kolo geidam; alhaji mustapha isa (2019). spatial analyses of suitable solid waste dumping sites in damaturu, yobe state nigeria. asian review of environmental and earth sciences, 6(1): 9-15. history: received: 25 october 2018 revised: 27 november 2018 accepted: 10 january 2019 published: 6 march 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: both authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 10 2. literature review ............................................................................................................................................................................ 10 3. methodology ..................................................................................................................................................................................... 12 4. data analyses ................................................................................................................................................................................... 13 5. result and discussion ..................................................................................................................................................................... 13 6. conclusion and recommendations ............................................................................................................................................... 14 references .............................................................................................................................................................................................. 14 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.9.15&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/711 http://asianonlinejournals.com/index.php/arees/article/view/711 asian review of environmental and earth sciences, 2019, 5(1): 9-15 10 © 2019 by the authors; licensee asian online journal publishing group 1. introduction increasing population levels, booming economy, rapid urbanization and the rise in community living standards have greatly accelerated the municipal solid waste generation rate in developing countries [1]. however, they often face problems beyond the ability of the municipal authority to tackle mainly due to lack of organization, financial resources, complexity and system multi dimensionality [1]. in nigeria, majority of inhabitants in most towns and cities often use unsafe solid waste disposal practices, such as open dumping, burning and burying [2]. as a result, many households practice uncontrolled open dumping and others employ various household solid waste disposal practices, such as burning, burying and composting. however, all self-managed waste disposal practices do not guarantee cleanliness and safety. similarly, in damaturu town, the study area, there are inadequate or inappropriate solid waste disposal sites. there are no scientifically approved sites and no standard transfer stations in the city. all health institutions and industries follow their way of removal of waste, while some others dispose it to the nearby water body, bushes and farmlands. the dumping sites are not well planned and are usually open field close to settlements or at the heart of the city center. in order to alleviate these problems, integrating gis and remote sensing techniques to select the best possible solid wastes dumping sites is a recent essential technology [3]. the selection of solid waste disposal sites using gis and remote sensing requires many factors that should be integrated into one system for proper analysis. the selection criteria should consider and combine surface water, soil type, slopes, settlements, groundwater, protected areas, land use and road networks. however, because of absence of data geology, groundwater data were not included in the study. remote sensing can provide information about the various spatial criteria such as land use/land cover, drainage density, slope, etc [2] whereas gis aided utilizing and creating the digital geodatabase as a spatial clustering process and easily understood way for solid waste dumping site selection process. in multi-criteria evaluation many data layers are to be handled by gis and remote sensing in order to arrive at the suitable site, this can be achieved conventionally using gis. therefore, the study was aimed at proposing suitable solid waste disposal sites by using gis and remote sensing techniques in order to minimize risk of ecological and human health problem in damaturu town. it is also helpful to set appropriate selection criteria for the identification of new solid waste dumping sites through scientific methods [3]. therefore, locating proper sites for solid waste disposal and selecting appropriate landfill site far from residential areas, environmental resources and settlement is the main issue for the management of solid waste. one way to dispose solid waste is to place it in properly designed, constructed, and managed landfills, where it is safely contained. many studies suggested that the solid waste dumping site should be located within a 1 km buffer from the roads and other transportation facilities chang, et al. [4]. sener, et al. [5] had shown that the distance between disposal sites and settlement areas must be more than 1000 m and the haul distance between the solid disposal site and the main city center should not exceed 30 km. land use types such as grassland, forests, agricultural land, wet land, bush lands should be considered in designing appropriate land use suitability for solid waste dump. in nigeria however, the proximity analysis based on the national environmental standards and regulations enforcement agency (nesrea) used at distances 1000m, 500m and 250m showed that built-up areas, major roads, and watercourses fall within buffer range to dumpsites [6]. the present study employed gis techniques to arrive at the most suitable solid waste disposal site by integrating some factors such as: proximity to road networks, distances from residences and important built up areas as well as watercourse. application of gis and multi criteria decision analysis is desired in site selection problems. gis is flexible in considering criteria and it is possible to develop this method by taking into account other effective criteria that helps in the finding suitable sites for waste dump. multi criteria decision analysis provides necessary conditions to consider in site selection evaluation and therefore helps decision makers towards correct option selection. gis combination with decision analysis as decision supporting system can assist decision makers in making the right choice for waste dumpsite site [7]. 1.1. summary in summary, the use of geographical information system as an effective tool to assess and manage dump sites in damaturu town for a sustainable development will help to identify suitable location for municipal waste dump which would have minimum impact on the environment. it will also help in monitoring possible environmental problems for effective and proper management of solid waste in dump sites. this study therefore, is aimed at providing a frame work for effectively selecting suitable solid waste dumping site for sustainable waste management in damaturu, yobe state using geo-spatial analyses. 2. literature review 2.1. the concept of solid waste management strategies and measures commonly adopted for municipal solid waste management in most of the cities in nigeria create the wrong impression that solid waste management problems are daunting and intractable task. this came from the simple fact that the rate at which solid waste collection and subsequent disposal is done is in no way closer to the rate of waste generation. this makes solid waste accumulation one of the major municipal solid waste is defined as that type of waste collected and treated by, or for municipalities [8]. this includes waste from households, bulky waste, similar waste from commerce and trade, office buildings, institutions and small businesses, yard and garden, street sweepings, contents of litter containers, and market cleansing. waste from municipal sewage networks and treatment, as well as municipal construction and demolition is excluded. solid waste management is a daily routine that is continuous and never finished. as each day passes, it brings new task of streets to sweep, waste to collect, waste loads to haul and safely to dispose. urbanization and solid waste generation are closely interrelated. in many fast-growing cities of developing countries, dealing with household waste has become a vital policy problem. policies and regulations aimed at good management of wastes, ranging from specifically controlling wastes at the household level to integrated municipal and economy-wide waste reduction efforts have been implemented with mixed outcomes [9]. asian review of environmental and earth sciences, 2019, 5(1): 9-15 11 © 2019 by the authors; licensee asian online journal publishing group scarcity of land for waste disposal in most large urban areas is one of the serious and growing potential problems nowadays. even though there are some efforts to reduce and recover the waste, land filling is still the most common method for waste destination. landfill and dumpsite selection in urban areas is a critical issue due to its huge impact on the economy, ecology, and the environmental health [10]. in africa, it is currently estimated that, the rate at which solid waste is growing in urban areas is much faster than the urbanization itself [11]. this may not be unconnected with rapid urban growth in the continent since the 1960s which has put pressure on land resources within the areas surrounding cities and led to increased generation of waste. the problem is aggravated by the open dump nature of disposing waste especially in the slum areas of most african cities [12]. the imperfect environmental nuisances in most cities in nigeria [13]. the huge volume of solid wastes that are commonly visible in most of the roads and streets of our major cities in nigeria is an indication that the current adopted strategies to cope with the unavoidable bye products of development appeared to be ineffective. what is common practice in developing world is dumping in open areas, along the roadsides and valleys and rivers and also within the cluster of houses. many studies have investigated the determinants of various behaviors and attributes on the dumping practices for household waste [9]. however, little is done on the application of scientific tool such as the gis and multi criteria decision technique for suitability analyses of solid waste disposal site, particularly in cities and towns of developing countries like nigeria. identification of the suitability of potential landfill sites, and modifications to existing facilities, requires a comprehensive assessment of site conditions and potential impacts on the environment. this includes consideration of topography, surface water, drainage, hydrogeology (groundwater), geology, climate (including air quality and odor modeling) and flora and fauna, access and distance from the community the landfill will service [12]. 2.2. gis in waste management technological development in computer science has introduced geographic information system (gis) as an innovative tool in solid waste management including landfill process [14]. gis combines spatial data (maps, aerial photographs, satellite images, etc.) with non-spatial data including both the quantitative and qualitative. the role of gis in solid waste management is very large as many aspects of its planning and operations are highly dependent on spatial data [5]. in general, gis plays a key role in maintaining account data to facilitate collection operations; customer service; analyzing optimal locations for transfer stations; planning routes for vehicles transporting waste from residential, commercial and industrial customers to transfer stations and from transfer stations to landfills; locating new landfills and monitoring the landfill [14]. gis is a tool that not only reduces time and cost of the site selection, but also provide a digital data bank for future monitoring program of the site. one of the most important applications of gis is the display and analysis of data to support the process of environmental decision-making. a decision can be defined as a choice between alternatives, where the alternatives may be different actions, locations, objects, and the likes. the role of gis in solid waste management is very large as many aspects of its planning and operations are highly dependent on spatial data [7]. for instance, uwadiegwu and chukwu [13] developed an engineered design of solid waste collection using gis with a vehicle tracking system and final disposal by composting with investment costs. the gis was used to analyze existing maps and data, to digitize the existing ward boundaries and to enter data about the wards and disposal sites. the gis model for solid waste disposal would give information on the planning of bins, vehicles and the optimal route. in the case of disposal and composting, it would be a successful strategy to accelerate the decomposition and stabilization of the biodegradable components of waste in municipal solid waste management [14]. nowadays gis has been used as a tool in a dumpsite and landfill site selection analysis, it provides the decision makers with a powerful set of tools for the manipulation and analysis of spatial information. using gis, it is possible to process a huge amount of spatial data in short time and so the screening process is much easier. gis can help to reduce remarkably the areas that have to be examined on the site, although the final decision has to be taken after field studies [10]. site selection analysis can be improved by using gis, since it has the capability to manage large amount of spatial data that comes from various sources. danbuzu, et al. [14] pointed out that large amount of spatial data can be processed using gis and thus, it potentially saves time that would normally be spent in selecting an appropriate site. while akbari, et al. [15] claimed that gis is an ultimate method for preliminary site selection as it efficiently stores, retrieves, analyzes and displays information according to user-defined specification. however, gis can be limited by the existing sources of data needed in siting analysis [10]. 2.3. criteria for site selection the factors to be considered as criteria for selection of suitable sites mainly consist of: public health, extend and topography of the area, hydrology, geology drainage system and weather of the area, proximity to the residential and industrial areas, the distance to and from the city, the weather of the area, the drainage system of the area, cost and the future land use of the area [4]. a waste dump site must be situated and designed to meet the necessary conditions for preventing pollution of the soil, groundwater or surface water and should be kept as far as possible away from population density, for reducing pollution impact to public health. also, aziz and khodakarami [7] emphasis that waste dumpsite should not be placed as close as possible to existing roads and also not too far from the roads in order to minimized cost of road development, transportation, and collection costs. some suitability criteria, commonly used as criteria for analysis for dumpsite suitability selection is described as follows; residential areas: dumpsite or landfill site should be located away and far from populated centers of the city, as it causes aesthetic, bad odors and depreciation of land value of the surrounding area [7]. in a study by bera, et al. [16] in india, they opined that dumpsites should not be placed too close to high-density urban areas in order to mitigate conflicts relating to the not in my back-yard syndrome (nimby). this helps to protect against health asian review of environmental and earth sciences, 2019, 5(1): 9-15 12 © 2019 by the authors; licensee asian online journal publishing group problems, noise complaints, odor complaints, decreased property values and mischief due to scavenging animals. sener, et al. [5] stated that in turkey, dumpsites are to be located within 1000 m of settlement areas. however, in nigeria, olaide, et al. [6] reported that for built-up areas, national dumpsite was placed at least 1000m away from all settlements for hygienic reasons. road network: aesthetic considerations would be of good practice for good planning and based on this principle, waste dumpsites should not be located within 1000 meters of any major highways, city streets or other transportation routes [16]. however, in nigeria, 2000 meters away from existing roads was chosen under nesrea guideline so as to reduce transportation expenses [6]. in another view, waste dumpsite is suggested not be placed too far away from existed road networks. it should be sited in such a location that can be reached by alternative roads under all weather conditions. hence, it is required that a distance of <1000 m away and >250 m away is desired as suitable dumpsite [5]. proximity to water bodies: water bodies such as; surface streams, lakes, rivers, wells, or wetlands are one of the major factors to be considered when siting waste dumpsite. also, proximity to wells and other underground water reservoir is an important criterion to be considered when locating suitable waste dumpsite [7]. according to bera, et al. [16] solid waste dumping sites must not be located near any surface water body such as streams, lakes, rivers or wetlands. thus, significant distance is required to prevent problems of erosion and leaching of hazardous substances and buffer around all surface waters is required when siting suitable dumpsite. however, for watercourse in nigeria, dumpsite should be placed at least 1000m away from surface water bodies to avoid hazardous emission as well as leaching from waste under national environmental standards and regulations enforcement agency (nesrea) [6]. 3. methodology 3.1. study area yobe state is one of the 36 states in nigeria, with damaturu as the state capital. the state has 17 local government areas. it is located within latitude 11 north and longitude 12.5 east with a total land area of 47, 153 square kilometres. the state shares boundaries with borno state to the east and south-east, jigawa state to the north while bauchi and gombe states to the south-west. it also shares an international border with the republic of niger. this boundary stretches over 323km to the north of the state. according to npc [17] yobe had the population of 2.5 million. the vegetation of yobe state is generally savannah grassland. grasses, sparse dwarf trees and shrubs are the most common features of the state. figure-1. the study area. source: google earth map. asian review of environmental and earth sciences, 2019, 5(1): 9-15 13 © 2019 by the authors; licensee asian online journal publishing group human activities such as farming and grazing of animals are the major sources of household wealth and income in the state and are worsen desert encroachment. yobe state government encourages tree planting campaigns in other to control desert enrichment especially at the northern part of the state. the state is multi-ethnic with kanuri, bade, fulani, ngizim, bolewa, kare-kare, ngamo, babur/maga, hausa and other nigerian groups constituting the main groups in the state. the hausa language is widely spoken in the state. with regard to the economy the state yobe is relatively small compared to her counterparts such as lagos, kano and borno in nigeria. the gross state product (gsp), which evaluate the output of annual economic activities of the state, was estimated to be about us$222.99 compared to the national average for the same year put at us$887.63. the state economy makes contributes about 0.42% to the national gross domestic product (gdp). 3.2. sampling frame as this study relied on secondary data, the nature of sampling differs from those of primary data, hence, the study considers the population of damaturu town as the population of the study in order to determine the required number of dumping site around the town. the estimated population of the town based on npc [17] it was about 110,000 people (about 18,000 households). also, based on available literatures on solid waste management in nigeria [6, 13, 18] quantity of waste generated in urban centers in nigeria is to the tune of 500 to 850 metric ton daily, with each dumpsite serving average of 1,000 households. thus, this study based on the number of the households in the study area, and the average number of households per dumping site, it therefore estimated to have about 6 suitable dumping sites at the outskirts of damaturu town. 4. data analyses 4.1. geo-referencing and digitization images for 2018 of the city, landsat 8 operational land imager thermal infrared sensor for the month of march was downloaded free of charge from the united states geological survey (www.earthexplorer.usgs.gov). these images were already geometrically corrected but little radiometric and atmospheric corrections were applied since the time of image acquisition coincided with the dry season when no clouds were present in the sky. however, the corrections removed some of the few impurities associated with the image and generally improved its visual quality. the city was then digitized and clipped from the image using the shape file already obtained. the clipped image was then imported to arcmap from which, digital maps were produced. population density map was produced base on field experience and satellite imagery observation. land uses and housing pattern were used as guide. shape files were also created for the following features; roads, rivers, (waterbody), and settlement. on screen digitizing was done for all the created shape files from the imagery. 4.2. geospatial analysis the basic spatial analysis employed during this work was buffering operation and proximity analysis was also demonstrated in the arcgis environment. buffers of specific distance were created around the city and the dumpsites so as to determine the proximity level of the dumpsites to the roads, rivers and the built-up areas. 4.3. site selection criteria for the selection of the most suitable site for dumpsites and sorting centers, the following criteria were considered for the available datasets. the proximity analysis based on the national environmental standards and regulations enforcement agency (nesrea): for built-up areas, dumpsite was placed at least 1000m away from all settlements for hygienic reasons. i. for watercourse, dumpsite was placed at least 1000m away from watercourses to avoid hazardous emission from waste. ii. for roads, dumpsite was placed at least <1000m away from an existing road so as to reduce transportation expenses. iii. for elevation, dumpsite was placed on slopes with less than 9% inclination. 5. result and discussion geospatial analysis using arcgis was conducted to identify the most suitable sites for waste dump in damaturu town, yobe state. 6 suitable candidate sites were determined on the basis of accessibility and significant distances from residents, roads and water bodies. all sites within 1000m away from residences and the major roads were determined as the most suitable sites for the municipal solid waste disposal. these sites as shown in the map figure 1 are located in different part of the town. the major goal of the municipal solid waste dumping site selection process is to ensure that the disposal facility is located at the best possible location with little negative impact to the environment. using arc gis 10.1 software creating different thematic layer and overlay analysis were done and identify six points as suitable for solid waste dumping zone in damaturu figure 2. the selected zones are on an open free space and grass land area. asian review of environmental and earth sciences, 2019, 5(1): 9-15 14 © 2019 by the authors; licensee asian online journal publishing group figure-2. waste disposal sites in the buffer zone. source: google earth map. 6. conclusion and recommendations the use of geographic information system in spatial analysis especially when representing the real-world phenomenon, helps in the integrating and simplifying the interpretation of a distribution of a facility especially the visual analysis and interpretations. gis play a significant role in solid waste management system as it helps the managers in database creation and the stakeholders to know the exact areas where there is need for more attention rather than concentrating on a particular area. this study used the integration of gis and remote sensing in identifying the best sites for the dumping the solid waste material in a typically urbanizing city. a multi-criteria approach was employed in conjunction with gis-based overlay analysis to identify the most suitable site for solid waste dumping in the damaturu. the study was based upon a set of key criteria, which were selected in relation to already available knowledge from research literature as well as the pre-existing local level factors of the area. a set of six (6) potential sites were identified as the most suitable sites for solid waste dumping in damaturu town. the integration of gis and remote sensing techniques contributed to the achievement of the results obtained. remote sensing techniques made it possible to study the various land cover types within the study area whereas gis aided in the modeling and preparation of needed maps. indeed, it has been an effective and efficient tool in carrying out this study. the sites selected as the suitable locations for waste dump are expected to serve the purpose for of protecting downstream surface water pollution, runoff and nuisance to the public. the present study considered a few of environmental, social and economic factors for solid waste dumping site selection. however, other factors such as geology, elevation, slope, ground water table depth etc. and community preferences were not considered as part of the suitability criteria, partly because of expensiveness of remotely sensed data. hence, further study should fill this research gap by including these layers as part of the suitability criteria. references [1] l. a. guerrero, g. maas, and w. hogland, "solid waste management challenges for cities in developing countries," waste management, vol. 33, pp. 220-232, 2013. available at: https://doi.org/10.1016/j.wasman.2012.09.008. [2] u. u. solomon, "the state of solid waste management in nigeria," waste management, vol. 10, pp. 2787-2788, 2009. available at: https://doi.org/10.1016/j.wasman.2012.09.008. [3] t. a. ebistu and a. s. minale, "solid waste dumping site suitability analysis using geographic information system (gis) and remote sensing for bahir dar town, north western ethiopia," african journal of environmental science and technology, vol. 7, pp. 976-989, 2013. asian review of environmental and earth sciences, 2019, 5(1): 9-15 15 © 2019 by the authors; licensee asian online journal publishing group [4] n.b. chang, g. parvathinathan, and j. b. breeden, "combining gis with fuzzy multicriteria decision-making for landfill siting in a fast-growing urban region," journal of environmental management, vol. 87, pp. 139-153, 2008. available at: https://doi.org/10.1016/j.jenvman.2007.01.011. [5] s. sener, e. sener, and b. nas, "selection of landfill site using gis and multicriteria decision analysis for beysehir lake catchment area konya, turkey," journal of engineering science and design, vol. 1, pp. 134-144, 2011. [6] a. olaide, s. salis, a. susan, n. blessing, j. jagila, a. rasheed, and f. olayinka, "a geo-spatial approach for solid waste dumpsites for sustainable development in minna, niger state, nigeria," journal of environmental science, toxiology and food technology, vol. 18, pp. 16-28, 2014. available at: https://doi.org/10.9790/2402-081011628. [7] r. s. aziz and l. khodakarami, "application of gis models in site selection of waste disposal in an urban area," presented at the in first international symposium on urban development, 2013. [8] organization for economic development and co-operation, oecd key environmantal indicators 2008. paris, france: oecd environment directorate, 2008. [9] t. tadesse, a. ruijs, and f. hagos, "household waste disposal in mekelle city, northern ethiopia," waste management, vol. 28, pp. 2003-2012, 2012. available at: https://doi.org/10.1016/j.wasman.2007.08.015. [10] m. a. mohd din, z. wan jaafar, m. m. obot, and m. a. wan hussin, "how gis can be a useful tool to deal with landfill," presented at the in international symposium on geoinformatics for spatial infrastructure development in earth and allied sciences, 2008. [11] d. hoornweg and p. bhada-tata, "what a waste: a global review of solid waste management. urban development series, world bank," 2012. [12] g. berisa and y. birhanu, "municipal solid waste disposal site selection of jigjiga town," international journal of physical and human geography, vol. 4, pp. 1–25, 2016. [13] b. uwadiegwu and k. chukwu, "strategies for effective urban solid waste management in nigeria," european scientific journal, vol. 9, pp. 296–308, 2013. [14] l. danbuzu, a. tanko, u. ibrahim, and m. ahmed, "spatial distribution of solid waste collection points using gis approach in urban katsina, katsina state, nigeria," american journal of engineering research, vol. 3, pp. 107-116, 2014. [15] v. akbari, m. rajabi, s. chavoshi, and r. shams, "landfill site selection by combining gis and fuzzy multi criteria decision analysis, case study: bandar abbas, iran," world applied sciences journal, vol. 3, pp. 39-47, 2008. [16] s. bera, m. ahmad, and a. kumar, "suitable site selection for urban solid waste management using gis technique-a case study of dhanbad block," international research journal of engineering and technology, vol. 3, pp. 1600-1605, 2016. [17] npc, nigeria 2006 census figures. abuja: national population commision (npc), 2006. [18] i. m. zumo, s. a. vokna, z. i. muhammad, and v. s. ahmad, "identification of suitable site for solid waste disposal in yola, nigeria using gis method, (6846) identification of suitable site for solid waste disposal in yola, nigeria using gis method," 2014. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 3, 42-53, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 42 environmental impact assessment and sedimentology of the carbonate quarry site for al-maroua'ah cement plant in al-hodeida district, nw yemen sa'ad zeki a. kader a.kader al-mashaikie 1* --abdul-kader mohammed al-karraz 2 1 dept. of geology, collage sciences, baghdad university, al-jadryiah, baghdad, iraq 2 dept. of marine environment, faculty of marine & environmental sciences, al-hodiedah univ. al-hodiedah, yemen abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 43 2. methods and materials ............................................................................................................................................................. 43 3. quarry site and characterization ........................................................................................................................................... 43 4. description of the natural environment ................................................................................................................................. 45 5. ambient air quality and levels of noisiness ......................................................................................................................... 46 6. potential environmental impact .............................................................................................................................................. 47 7. type of air pollution................................................................................................................................................................. 47 8. weather and topography ........................................................................................................................................................ 47 9. dispersion modeling system .................................................................................................................................................... 47 10. limitations ............................................................................................................................................................................... 49 11. environmental mitigation plan ............................................................................................................................................. 50 12. conclusion ................................................................................................................................................................................ 52 references ...................................................................................................................................................................................... 52 in this study, environmental impact assessment and sedimentology includes chemical analysis were carried out for the quarry site of the limestone raw material in al-maroua'ah cement plant in tehama plane, al-hodeida district nw yemen. the study includes the assessment of the limestone raw materials, the quality, chemical and mineralogical analysis and expected pollutions impact in the quarry site. the studied rock successions are belonging to the amran group, which is composed mainly of limestone rocks with few interbedded marl, shale and sandstone beds. the chemical analysis of the limestone rocks show cao content is (50.31%), with very little mgo content (0.71%). the present shale marl and sandstone rock units are useful for the correction of the rocks to concise with the international specifications of the cement production. the site of the quarry of the main raw materials of limestone rocks was selected far from the villages and human populations to prevent the environmental pollutions according to the who and yepa specifications. the emitted dust from the operations of the quarry machine makes impacts on the surrounding environments especially for the farms and the natural plants and animals, which are living in the region. for this, the site of quarry is selected in a mountain far from the vegetation, population and villages to avoid the expected environmental impact. mitigation plan for prevent or decreases the pollution impact to the minimum, was discussed. keywords: al-maroua’ah, eia, limestone, quarry, chemical analysis, dust pollution, gases pollution, management plan. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(3): 42-53 43 1. introduction al-maroua’ah cement factory is significantly contributed in the development of the yemeni economy after operating in early 2015. the plant management had adopted the commitment to improve the local economy of alhodiedah governorate, and the region where the plant exists, to provide jobs for the citizens of the governorate and of the region in particular, in addition to the medical and educational services proposed to be provided in the plant region, as well as the erection of the integrated residential city for the staff and the labors of the plant. the cement production capacity in al-maroua’ah cement factory reaches up to 3,000,000 mt of cement. this study had been produced to assess the environmental impacts of the operations held in the quarry of the raw materials and the resulting residuals of such operations followed the limitation of the epa [1]. the plant management undertakes to apply the yemeni environment management plans proposed in this study; including the measures of reducing the emissions; and the continuous environmental monitoring program. moreover, this study deals with the assessment of the carbonate rocks as the main raw materials in cement production. 2. methods and materials the evaluation of the quarry and the raw materials for cement production and its environmental impact includes field works and survey as well as chemical analysis. the field works include the selection of the quarry site according to the international specification to prevent the environmental pollution as well as the systematic sampling of the limestone raw materials for quality evaluation. it will exploit the falafel mountain to supply the factory for raw materials (limestone). the ei assessment was followed the parameters listed in the epa [1] and national [2] falafel mountain was divided into three areas for exploit and the details of these areas and coordinates are listed in figure 1. twenty five (25) rock samples were collected and later prepared and analyzed by xrf in the lab of alwatanyiah cement plant in lahg governate followed the procedure listed in tucker [3]. the results were interpreted and the rocks were evaluated for cement production. 3. quarry site and characterization the quarry site is lying in jabal falafel mountain in al-maroua’ah region, 36 km east of al-hodiedah governorate, and 4-5 km from the main road connect al-hodiedah with sana’a city (fig.1). jabal falafel mountain lies near dear daood village, which is situated in tehama plane parallel to the coast of the red sea. some of these areas are agricultural farms with abundant underground water in all seasons of the year. the land surface of the region is located at an elevation of about 120 meters above the sea level (fig.1) the primary raw materials used in the production of cement are usually provided from limestone quarries, which are generally located near the plant site to reduce transportation and production costs, whereby the limestone bedrocks are the most important imperative raw materials for cement industry. the limestone rocks are extracted by drilling and explosion before being transported by conveyor belts or heavy trucks. later on, the extracted rocks are subjected to cracking and screening processes to specify the grain size, and finally stored [4]. the heavy trucks working in the quarry discharge the cargos in the funnel-shaped container (hopper), which is supported by series of sieves to separate pieces of large from the smaller rocks, thereby curtailing the load and effort of the initial crusher. the large rocks are broken down and the sizes are reduced (size of product 90% less than 25mm) before passing over conveyor belt which transfers the raw materials through gamma automatic analyzer, and thereafter, they store in opened sheds yard [4, 5]. 3.1. sedimentology and quality of the limestone the limestones is belonging to amran group and cropping out in jabal falafel mountain, which is laying near the site al-maroua’ah cement plant. the carbonate rocks include successive and interbedded massive and bedded limestone and marls of about 500 m thick [6]. thick massive sandstone bed of 25 m thick is interbedded with limestones. the limestones are composed of lime mudstone, packstone, grainstone and wackestone microfacies flugel [7] and scholl and ulmer-scholl [8]. it is mainly composed of calcite and micrite, with very rare dolomites, which represents very good quality for cement production [4, 5]. the sandstone is basically composed of silica grains and partial cemented with argillaceous matrix. 3.2. chemical analysis the chemical analysis was carried out using xr-fluorescence instrument type thrmo in the lab of alwatanyiah cement factory and the data is listed in table (1) which shows that is relatively pure with high to very high cao% and low mgo%. the silica, aluminum, iron oxides and alkalis are very low. thus, the raw materials require substantial correction with argillaceous, siliceous and ferruginous materials. asian review of environmental and earth sciences, 2015, 2(3): 42-53 44 fig-1. location map of yemen shows the site of al-maroua’ah cement plant and the quarry site (the colored blocks), at jabal falafel mountain (sat image-google earth). fig-2. field photograph shows the extraction processes of limestone table-1, shows the chemical analysis data of the limestone and other raw materials in the study area. asian review of environmental and earth sciences, 2015, 2(3): 42-53 45 4. description of the natural environment topography of the site is located at height of about 120 m and the mountains altitudes around is reaching 400 m height a.s.l. and 300 m above land surface .the area is gradually sloping towards the west and expands in all directions as wide planes extends for hundreds of kilometers [9]. 4.1. climate and water metrology the tehama region is of arid climate, extremely hot during winter months (november to march) when temperatures range from 20c 0 to 30c 0 . the mean monthly maximum temperatures are ranging from 32c 0 in january to 39c 0 in june. annual precipitation is 100 mm in the costal line to 400 mm near the foothills and mountains, most of which occurs in april to october. the annual evapotranspiration is about 1864 mm/year. the region is characterized by high relative humidity with average of 71-76 %. the wind in tehama plane (includes al-maroua’ah area) is of southern general direction (table.3). the annual average values of sunshine in al-hodiedah governorate range between 7 to 10 h/day, which correspond to 50 to 75 % of the theoretical maximum. the monthly sunshine duration in al-hodiedah governorates ranges from 7 h/day in july to 10 h/day in november. 4.2. biology and agriculture farms many types of trees are considerably proliferating in the mountains surrounding the factory site. the agricultural fields are spreading down on the lands surrounding falafel mountain, which sometimes expands to distance more than 2 km. corn and vegetables cultivation as well as mango farms are widely spread throughout the valleys (pl/1, a, b, c). 4.3. natural environments in almaroua’ah area represents one of mountainous regions, which includes relatively high biodiversity and provides significant habitat for the birds and their migration to other regions. most of native and semi-origin animals and plants exist in the study area, such as: hemitragus jayakari, the arabian gazelle (gazella gazelle), the mountainous caribou (capra ibex nubiana), the striped hyaena (hyaena), the wild cat (felis sylvestris) and the panther (panthera xanthopygos). the types of the birds exist in the region are yellow-incision nightingale (pycnonotus xanthopygos), songbird (prinia gracilis), brown songbird (phylloscopus umbrovirens), yemeni apple bird (carduelis yemenensis), dark skin flycatcher bird (muscicapa gambagae), arab partridge (alectoris melanocephalia), and black shuhite bird (milvus migrans) [2, 10]. falafel mount is a barren area in which do not grow any plants, but there are some trees from acacia type (pl/1, d). 4.4. human populations in the republic of yemen had a high population growth ratio reaches 3.5% in the recent decades. this immense population expansion created certain risk to the scarce environmental system and threatened the great biodiversity and the bio-natural fortune in the country. 4.5 water resources come from rain-fed, which is inadequate in all districts of northern tehama except for dry cropping where low rainfall is about 50% below evapotranspiration rate during the most days of the year. consequently, groundwater is the main and supplementary source of irrigation . impact of overexploitation of deep aquifers results in depletion of groundwater table from 1-7 m/year. sources of irrigation in al-hodiedah governorate are shown in (table. 2). it is unexpected to note that groundwater in irrigated area was retreated in 2004 to 2008 despite the lack of control measurement for the resource [2, 11, 12]. table-2. shows cropped area by sources of irrigation, al-hodiedah area. source: [11-13]. table-3. meteorological data of al-hodiedah district from 1995 to 2008. source: fao [14] asian review of environmental and earth sciences, 2015, 2(3): 42-53 46 plate-1. field photographs show the plant diversity in the agriculture farms and natural trees in jabal falafel mountain. a. the corn farms near al-maroua'ah site of the cement plant. b. the mango trees near al-maroua'ah site of the cement plant. c. the wide extended agriculture farms in the vicinity of al-maroua'ah plant site. d. the acacia natural trees in the vicinity of al-maroua'ah plant site. 5. ambient air quality and levels of noisiness most regions in the republic of yemen do not possess scientific data about the air quality and levels of noise. in this study, efforts were exerted to collect database upon air quality and levels of noise in the region of al-maroua’ah cement plant. it is worth mentioning that this region is situated 5 km from the main road connect sana'a and alhodiedah cities and far from villages, noisiness and crowded people and markets. al-maroua’ah area is characterized by proliferation of agricultural lands on both sides of the mountain, where the people is working in agricultural and the fields of cattle breeds and sheep herding. no air pollutant was found, while the vehicles traffic is few, quiet life atmosphere is prevailing and population density is low (table 4). the data of the air quality and dust concentrations in al-maroua’ah area is lying within the limits of the standards of eu [15] aaep [16] epa [1] and (table.5). air pollution comes from operating of the quarry machines (shovels, trucks and crushers), which produced dust, carbon dioxide and associated gases. production of 3000 tons/day cement creates pollution of dust and co2 gas emitted to the surrounding environments e.g. natural and agriculture plants as well as animals and people. the pollution is coming from; (1) explosions of dynamite in the quarry, (2) shovels transport the raw materials to the main crusher, (3) viechels and trucks transport the raw materials. three types of crushers are operating to crush the limestone raw materials to smaller size and produce two essential types of impact; dust and gases in the air, and noises. table-4. collected data of dust concentrations in the air of certain localities in al-maroua’ah cement plant site in the morning (in field work). table-5. proposed standards in view of air quality [1, 15, 16]; asian review of environmental and earth sciences, 2015, 2(3): 42-53 47 6. potential environmental impact the potential environmental impacts are resulted from different stages of operation of al-maraoua'ah cement factory. the important pollutions include air, surface and ground waters, soil, biodiversity, methods of utilizing of the natural resources, health and safety factors, impact on the landscapes, social and economic indices in the region. assessment of impacts is determine using quantitative uses of the analytical equipment's and computing methods, while other pollution can be identified in term of the qualitative comparison and description in accordance with the previous observations [17, 18]. consequently, assessment of the environmental pollution impacts is directly linked to the definition of those locations, which may be exposed to pollution, including local areas, hospitals, residential areas, schools, offices, factories, commercial shops, mosques, sports stadiums and recreation places. it is worth emphasizing that the site of the project is located in rural agricultural area, where villages and agricultural farms are distributed in the region, with absence of cities, public governmental or private facilities. the locations which are exposed to pollution and close to the plant site are the surrounding villages, the residential units which shall be erected for the plant labors and staff, and the agricultural fields (fig. 3; table.6). 7. type of air pollution this study focus on the assessment of the anticipated environmental impacts in terms of kinds of the air pollution, which may appear during the quarry processes and mainly resulting from the smelting operations of raw and grinded materials to produce 3,000,000 t/y of clinker in al-maraoua'ah cement plant. it is well known that the quarry process of the raw materials is characterized by emission of immense quantities of dust and gases; which are generated due to the explosion of dynamites and the primary and secondary crushing and grinding of the limestone raw materials near the quarry. moreover, the operations of the shovels, viechels and machines are emitted real quantities of carbon dioxide and associated gases, which are pollute surrounding areas. the grinding of limestones to finer size, leads to inevitably significant emissions of dust. the size and composition of the emitted dust particles mainly depend upon the characteristics of the primary raw materials. (table 6) table-6. types of the emitted dust and the reasons of the formation during different processes [19]. 8. weather and topography data of weather conditions and terrain are forming important input indices of impact of the dispersion of dust and gases emissions from the quarry source in open spaces. changes in weather conditions and topography may lead to change in the levels of concentrations at the exposure sites. hence, it is required to obtain hourly data on weather conditions during the year. the inserted data in the program is collected from the city of al-hodiedah, which enjoys weather conditions similar to those of al-maroua’ah area, where the air monitoring stations do not exist in the study area. al-maroua’ah area comprises simple topography, which lies in flat plane with scattered medium height mountains. the altitudes of the topography were calculated in the field survey and google earth utility through the international information network (internet) and using program gis and dem 90m for earth (nasa.usa). this survey indicates that the height of the ground surface of the site is 120 m and the mountains are 365 m and 400 m. there is important to classify the utilization of lands in the vicinity of al-maraoua'ah cement site, considering that the average dispersion is variable between the rural environment and the urban environment follow the general outlines of the usepa [15, 18]. epa is relevant to the air quality simulation programs depending on the factors of population density and land utilization methods as standards of classification. it is advised to apply the dispersion indices belonging to the rural environment. the site of the cement plant is located in agricultural region and occupies an area of 5 km 2 , where any kinds of industrial facilities do not exist. hence, the rural environment indices were selected to apply, considering that the vicinity surrounding the site has low population density and agricultural vicinity. 9. dispersion modeling system gis modeling using potential data is applying for annual pollution, which is plotted on topographic map of the area include villages and the cement plant site fig.6.5, 6.6. breeze isc gis pro version 4.1.3model was used with more accurate data, which is developed according to the model of usepa united states environmental protection agency [20] to assess the environmental impact of the dust and gases emissions. 9.1. dispersion of dust the adopted interpretative of illustrate the levels of concentrations are shown in table 5.10. in the absence of the control the pollution of potential emissions in the cement plant, wide area is exposed to emission levels exceed the health standards that permits by the epa [1] in terms of dust concentration. asian review of environmental and earth sciences, 2015, 2(3): 42-53 48 fig-3. shows the dust emission from the sources of the open spaces in the quarry site. table-6.6. proposed emission data produces from the sources of the open spaces in the cement plants. table-6.9. shows the approval probabilities in specify dispersion of emissions. fig-6.5. annually pm exposure levels in proposed production capacity of 3,000,000 tons/year (bat: best available technology). note the wind direction is pointed in the lower right edge of the photo. asian review of environmental and earth sciences, 2015, 2(3): 42-53 49 fig-6.6. annually pm exposure levels under proposed production capacity of 2,000,000 tons/year (bat: best available technology). note the wind direction is pointed in the lower right edge of the photo. 10. limitations several limitations were encountered in the present study. the absence of reliable and long-term site-specific data, which is required drawing on literature reported values that may not accurately describe the actual operational conditions at neither mcp nor the baseline environment in al-maroua'ah area. as such, it is imperative to implement suggested monitoring program and to reassess the results and validate the simulated exposure levels based on long-term and systematic monitoring data. the available models are far from being ideal and are simplifications of reality. models are only capable of providing rough overview of real time processes and are best used for comparison purposes. note also that all air dispersion models including isc exhibit increasing uncertainty with short-term average periods. this uncertainty decreases with increase average periods and as such predicted annual exposure levels tend to be more accurate than daily levels. 10.1. noise and vibrations noise is defined as “unwanted sound”. it has numerous adverse effects on people’s health as well as environment. several factors other than the magnitude of exposure typically influence community reaction to noise including duration of intruding noises and frequency of occurrence, time of year (windows open or closed), time of day of noise exposure, outdoor noise level in community when intruding noises are not present, history of prior exposure to noise source, attitude towards noise source, and presence of pure tones and impulses [18]. activities of quarry heavy machineries are generate high levels of noise, much of which can be reduced by properly sitting and insulating the operations area [21]. noise generation from the cement industry may either be permanent or intermittent. intermittent noise is mainly due to blasting, the daily starting of engines, and the loading of rocks into dumpers [22]. permanent noise generating sources can be divided into three main groups after [23]: dynamite explosion of the raw materials machine generated noise e.g. shovels, tracks, digging compressors and crushers. generally, the type and age of machines affect the level of noise generated. the older machines are usually emitting higher levels of noise. trucks and conveyers that transported the raw materials from the quarry to the plant site the assessment of the noise impacts resulting from the operation of the mcp plant under the current production capacity of 3,000,000 tons /year using two digital sound level meters (fig. 6.9). measured levels conformed to typical energy-equivalent noise levels that have been reported for the cement industry. the resulting noise levels exceed both daytime and nighttime yemeni noise standards set forth for rural and suburban residential areas, while the standard set forth for industrial areas is achieved within 2 km radius. l l 20log (x 250) 48 (1) the noise action on-site are of concern to on-site workers who are exposed to elevated noise levels for an average period of 8-hr. most measured noise levels are exceeding the occupational safety and health administration (osha) 8-hour occupational noise exposure standard of 90 (dba). asian review of environmental and earth sciences, 2015, 2(3): 42-53 50 vibrations on the other hand, are produced by blasting of limestone quarry and from heavy traffic on or off-site. the levels of generated vibration are generally below those that cause structural damage to properties. however, vibrations transmitted through the ground and pressure waves through the air (“overpressure”) shake buildings and may create nuisance. in this context, blasting is an issue of concern for the local people. for several residential units surrounding mcp, have complain that vibrations from the plant have result in property damage. fig-6.9. proposed noise meters used at mcp to measure ambient and industry related noise levels. table-6.13. show measurement of noise levels at mcp compared to typical energy-equivalent noise levels reported for the cement industry [22] nr: not recorded 1: measured at 7.5 m from source 2: value measured during the loading and transport of raw materials 11. environmental mitigation plan the primary potential adverse environmental impacts associated with the operations in mcp can be minimized by careful planning, adopt proper management practices, and relying on effective environmental monitoring. the mitigation plan suggests several potential impact-mitigation or control measures that will earn mcp more acceptability by eliminating or reduce the possible extent of impacts and intended to reduce the effect of potentially significant impacts on the environment. they are highly dependent on the significance of the predicted and the nature of the impact (permanent vs. temporary). 11.1. mitigation of air quality impact several mitigation measures are available to reduce the diverse environmental impacts that ambient air quality. these measures are compound specific and vary in the treatment efficiency as well as in technical and financial requirements. as such, air quality mitigation is ranging between bat and low-cost treatments. the mcp has planned to adopt several proposed mitigation measures to reduce dust emissions into the environment. the priority is clearly to mitigate pm dust emissions. the quarry processes emit considerable quantities of pm as a result of handling and grinding raw materials often to fine-grained size, which render dust emissions almost inevitable. the primary source of pm emissions includes fugitive and area source emissions that are generated from the handling, quarrying, and storage of raw materials. table 8.1 presents summary of mitigation measures that adopted at mcp. 11.2. mitigation of traffic impact primary measures adopted to mitigate traffic impacts include the proper dissemination of information regarding the transport schedule of limestone raw materials from the quarry site to the storage yards. in this respect, proper planning and development of a traffic plan that accounts for the reservations and inputs of nearby residents is essential to minimize potential inconvenience on commuters as well as to ensure the safety of motorists and pedestrians. as such, truck movements should be limited to off-peak hours to the extent feasible. in addition, adequate warning and signing are needed at least 500 m down and up-gradient from the entrance of the mcp to warn people that heavy equipment and trucks are frequent along these intersections. other traffic mitigation measures are presented in table 8.2. asian review of environmental and earth sciences, 2015, 2(3): 42-53 51 table-8.1. common control measures for particulate emissions from quarry processes of the raw materials 1: [17, 23-26]. table-8.2. traffic control measures in mpc. 11.3. mitigation of noise impact the outcome of the noise impact assessment reveals that noise levels in the areas surrounding mcp are higher than both daytime and nighttime according to the [27, 28] set for suburban residential areas. for this purpose, mitigation measures should be adopted in mcp to limit the impacts of noises on affected receptors. for this purpose, the erection of noise barriers to screen noise sources is proposed. usually, purpose-built noise barriers or screens constructed of appropriate material to be located along active work sites could result in noise reduction of up to 10 dba. it is anticipated that a movable noise barrier with a suitable footing and small cantilevered upper portion can be located within few meters of a static plant and about 5 m of mobile equipment. the provided insulation barriers can reduce noise impact up to 10 dba noise attenuation. in this case, noise levels may reach the daytime yemeni suburban noise standard (50 dba). additional mitigation measures include good site practice, selecting quieter mechanical equipment, as well as adopting proper schedule of construction activities. scheduling noisy activities during the daytime periods (7:00 am to 6:00 pm) will ensure that the noise standard set for the evening will not be exceeded at several instances. in addition, maintain proper onsite management to minimize noise emissions from the works during all times including: continuous maintenance for on-site machines, equipment intermittent in use are shut down between work periods, adopting low noise equipment, installing rubber coating in dumpers and entry chutes, using personal protection gear such as earplugs…etc, developing greenbelt around the quarry site, installing noise barriers around the quarry site, concerning mitigation measures that could be adopted to reduce ground vibrations generated particularly from blasting activities at the quarry site, mcp should adopt the following measures [22]: limit blasting to trained personnel, initiate periodic recording of blast vibrations, limit blasting activities to fixed days and hours that are acceptable with nearby receptors, disseminate the blasting schedule to nearby receptors, using mille-second delay detonator, deck charging, or other techniques to reduce vibrations and noise, increase the use of surface mining that do not require. 11.4. mitigation of soil, surface and groundwater impact the primary sources of potential impacts to water quality come from site runoff, which may directly enter soil, surface and groundwater waters. as such, open stockpiles of raw material should be covered with tarpaulin or similar fabric during rainstorm events to prevent the washing away, while earthworks at the quarry should be well compacted to prevent erosion especially during the wet season. furthermore, the installation of appropriate drainage system coupled with sedimentation tank is also imperative to re-duce exposure time to potential discharge sources. water from the settling tanks can be reused by mcp as process water or for irrigation and groundwater recharge purposes. efforts should also be made to clean the existing spillages in the wades where dried fuel spills should be collected and transported to a landfill while fresh fuel pools should be pumped in containers and re-used later on. other sources of potential water pollution include oil/fuel leaks and spills to the soil as well as the uncontrolled asian review of environmental and earth sciences, 2015, 2(3): 42-53 52 disposal liquid effluents. the improper handling of fuels at the fuel receiving area constitutes potential source of pollution at mcp. as such, fuel tanks should be bundled to limit the environmental damage, which is result from accidental spillage. bunds should be impermeable and resistant to the stored materials to avoid drains or taps that lead to blind collection point incorporate the distribution pipes within the bounded areas. in addition, oil and fuel residue that are generated from vehicle and machine service, vehicle wash bays and lubrication bays should also be mitigated to avoid potential soil, surface and ground water pollution. as such, oil-water separators and sand precipitators should be constructed, while oil collection trays should be provided to the operators at the vehicle and machine servicing areas [29]. spent motor oils should be collected in sealed containers and stored within closed drums located within the workshops until they are reused or recycled. oil contaminated cooling water should be treated in oil-water separators to remove oil. the treated water can be re-used to cool the flue gases in the conditioning tower as well as the cement mill [23, 29-31]. in case the suspended solids in the effluent are high in relation to the receiving waters, treatment may be required to reduce levels to maximum of 50 mg/l, which is the effluent requirement for direct discharge to surface waters [19, 23, 29-31]. 11.5. mitigation for terresterial biodiversity efforts should be made to preserve existing vegetation, avoid fires, prohibit hunting activities and the disposal of wastes of fuel and oil, hazardous in non-allocated areas, initiate a landscaping program on-site, as well as endorse well-planned restoration and reforestation plan for the quarry. the restoration and reforestation plans should be closely coordinated with al-hodiedah governorate and should use indigenous flora in re-vegetation schemes on-site since the use of exotic species hampers the re-colonization of the area by the local fauna. following closure to the quarry, several steps must be carried out to ensure the reintegration of the site with its surrounding including [15]: a) removal of wastes, b) reshaping of quarry walls to prevent unloading cracks and potentially dangerous collapse, c) reshaping of walls and loosening of compacted floors to facilitate re-vegetation and ensure the aesthetic quality of the restored landscape, e) retaining natural drainage on-site, f) re-vegetation using indigenous stocks of local vegetation such as the tamarix aphylla, salvadora persica, acacia spp, ziziphus spina-christi, commifora kataf and cadaba rotundifolia 12. conclusion environmental impact assessment and sedimenta logical study includes chemical analysis were carried out for the quarry site of al-maroua'ah cement factory in tehama plane, al-hodeida district nw yemen. the assessment of the quarry operations includes blasting of dynamite, shovels, trucks and primary crusher of the limestone raw materials was evaluated. the pollution includes dust emission, noise, gas emission from heavy duty viechels and fuel and oil waste were evaluates. mitigation plans was proposed to decrease the environmental impact for the minimum levels, which effected actually on the surrounding environments e.g. farms, populations, natural fauna and flora…etc. one of the most important point for mitigate pollution is the selection of quarry far from the villages and human populations to prevent the environmental impacts followed the specifications of who and yepa. the emitted dust and gases from the operations of the quarry machine makes impacts on the surrounding environments especially for the farms and the natural plants and animals, which are living in the region. for this, the site of quarry is selected in a mountain far from the vegetation, population and villages to avoid the expected environmental impact. mitigation plan for prevent or decreases the pollution impact to the minimum, was discussed. moreover, quality, chemical and mineralogical analysis for the limestone raw materials were also evaluated and expected pollutions impact was estimated. references [1] epa, "environmental guidelines for preparation of an environment management plan." environment and sustainable development directorate, act government. document. australian capital territory, canberra, 2013. [2] national, "national biodiversity strategy and action plan, sana’a, republic of yemen," ministry of water and environment/environmental protection authority (mowe/epa), report, 2004. [3] m. e. tucker, technique in sedimentology. oxford, london: blackwell scientific publication, 1988. [4] d. j. harrison, "industtrial mineral laboratory manual limestone," technical report wg/92/29 mineralogy ans petrology series. british geological survey, 1993. [5] l. walter and g. werner, "manual on the geological-technical assessment of mineral construction materials," geologisches jahrbuch, sonderhefte reihe h, heft sh 15bgr, bundesanstalt fur geowissenschaften und rohstoffe, geozentrum hannover, 2003. [6] z. r. beydoun, m. as-sururi, i. h. el-nakhal, i. al-ganad, r. baraba, a. s. nani, and m. al-awah, "international lexicon of stratigraphy, asia, fascicule 3(10b2), republic of yemen. sedimentary cover," z. geol. wiss., vol. 26, pp. 517-529, 1998. [7] e. flugel, microfacies analysis of limestones, book. berlin, heidelberg: springer-verlag, 1982. [8] p. a. scholl and d. s. ulmer-scholl, a color guide to the petrography of carbonate rocks: grains, textures, porosity, diagenesis. aapg memoir 77. tulsa, oklahoma, usa: published by american association of petroleum geologists, 2003. [9] geological assessment, "geological assessment of quarry limestone raw materials for cement industry in jabal falafel mountain, al-hodiedah goernerate. report," geological survey and mineral resources board (gsmrb), license and report, 2013. [10] a. j. alawi and n. v. mezhelovsky, republic of yemen: groundwater resources available for development. ministry of oil and mineral resources, geological survey and mineral resources board, sana’a,yemen. arya, s.p. air pollution meteorology and dispersion. new york: oxford university, press, inc. usa 1999, 1995. [11] yemeni, "yemeni standards for the discharge of industrial and commercial wastewater," (national water resources authority (nwra), sana’a, yemen, 1999. [12] a. w. a. iskander, "compiled. in collaboration with international & national technical consultant teams, republic of yemen ministry of agriculture and irrigation general directorate of farming irrigation in coordination with mop & ic. nt-mip," detailed technical studies on irrigation investment program for northern tehama modern irrigation project (nt-mip) final report-project, 2010. [13] mai, "ministry of agriculture and irrigation." agricultural statistics, book, 2007. [14] fao, "food and agriculture organization. appraisal of the groundwater resource in the amran region, sana’a governorate," technical report utf/yem/020/yem. sana’a, yemen, 1996. [15] guideline, "guideline on air quality models (revised)," epa-450/2-78-027r, u.s. environmental protection agency, research triangle park, nc 27711, united states, 1986. asian review of environmental and earth sciences, 2015, 2(3): 42-53 53 [16] usepa united states environmental protection agency, "air quality index: a guide to air quality and your health, office of air quality planning and standards." available http://www.airnow.gov/ [accessed 15 november 2004], 2002a. [17] usepa united states environmental protection agency, "population risks from indirect exposure pathways, and population effects from exposure to airborne particles from cement kiln dust waste," draft report. office of solid waste, united states, 1997. [18] usepa united states environmental protection agenc, protective noise levels: condensed version of epa levels document, 550/979-100. washington dc, usa: office of noise abatement and control, 1974. [19] pm10 sip development guideline, "epa-450/2-86-001, u.s," environmental protection agency usepa, research triangle park, nc 27711, united states, 1986. [20] usepa united states environmental protection agency, "key topics, air." available http://www.epa.gov/ebtpages/air.html [accessed 15 november 2004], 2002b. [21] epa, "guidelines for the preparation of noise management plans for development applications document." environment protection authority (epa), 2014. [22] wbcsd world business council for sustainable development, "towards a sustainable cement industry." available http://www.wbcsdcement.org, 2002. [23] iea international energy agency, tracking industrial energy efficiency and co2 emissions in support of the g8 plan of action (iea). france: head of communication and information office, 2007. [24] integrated, "integrated pollution prevention and control. guidance for the cement and lime sector," sector guidance note ippc s3.01. ea environment agency, bristol, uk, 2001. [25] inece international network for environmental compliance and enforcement, "training course for multimedia inspectors. industrial processes. cement industries." available http://www.inece.org/mmcourse/chapt6.pdf [accessed 1 december 2004], 1998. [26] i lo codes of practice, i lo codes of practice, protection of workers against noise and vibration in the working environment. switzerland: international labour office geneva, 1984. [27] m. c. barrientos, d. c. lendrum, and k. steenland, occupational noise, assessing the burden of disease from work-related hearing impairment at national and local levels, environmental burden of disease series, no. 9. series editors a. p.üstün, d. c. lendrum, c. corvalán, and a. woodward. geneva: world health organization (who), protection of the human environment, 2004. [28] s. z. k. al-mashaikie and a. k. al-karraz, "environmental impact assessment of al-maroua’ah cement plant factory in alhodiedah governate," yemen, report, 2013. [29] world bank, pollution prevention and abatement handbook part iii: cement manufacturing. washington, dc: world bank, united states, 1998. [30] awma, awma air and waste management association, air pollution engineering manual. new york: van nostrand reinhold, 1992. [31] npi national pollutant inventory, "emission estimation technique manual for cement manufacturing," version 2.1, department of the environment, water, heritage and art, australian governate, documaet, 2008. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://www.airnow.gov/ http://www.epa.gov/ebtpages/air.html http://www.wbcsdcement.org,/ http://www.inece.org/mmcourse/chapt6.pdf 28 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 28-37, 2019 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.28.37 © 2019 by the authors; licensee asian online journal publishing group engineering properties of some basement rocks of nigeria as aggregate in civil engineering pavement construction falowo olumuyiwa olusola department of geology, university of benin, benin city, edo state, nigeria. abstract the engineering performance of construction materials is strongly related to their physical properties. therefore in order to determine the suitability of the rock units in northern parts of ondo state, nigeria as aggregates for pavement construction, eight rock samples comprising porphyritic granite, granite, migmatite, granite gneiss, quartz schist, granodiorite, charnockite, and quartzite, were subjected to physical tests which include moisture content, dry density, porosity, specific gravity, aggregate impact value, aggregate crushing value, point load strength index, unconfined compressive strength, and shear strength. the tests were conducted in accordance to astm d2216 and isrm-2386 standard test methods. the aggregate impact value of the samples ranges from 11.2 (quartzite/granite gneiss) to 17.3 (charnockite), while aggregate crushing value varies from 18.4 (quartzite) to 25.2 (charnockite). the water absorption of the rock units ranges between 0.27 and 0.82%, and porosity recorded 0.18 – 0.46%. point load strength index, shear strength, and unconfined compressive strength of the samples ranges from 7.40 9.87, 60.5 – 92.6mpa, and 121.1 – 185.3 respectively. the values of aiv and acv are within the standard specification value for road material, cement concrete pavement and wearing surfaces of 30% and 45% maximum. therefore the rock units are very excellent as aggregate for road pavement construction and categorized as strong aggregate in terms of quality for road pavement. it is also observed that porosity and specific gravity are the major parameters that show strong positive correlations (≥0.5) with important geotechnical parameters such as shear strength, unconfined compressive strength, and point load strength index. keywords: construction material, aggregate, pavement, aggregate impact value, aggregate crushing value, point load strength index. citation | falowo olumuyiwa olusola (2019). engineering properties of some basement rocks of nigeria as aggregate in civil engineering pavement construction. asian review of environmental and earth sciences, 6(1): 28-37. history: received: 10 june 2019 revised: 12 july 2019 accepted: 20 august 2019 published: 1 october 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. competing interests: the author declares that there are no conflicts of interests regarding the publication of this paper. transparency: the author confirms that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 29 2. literature review ............................................................................................................................................................................ 29 3. description of study area .............................................................................................................................................................. 29 4. material and methods ..................................................................................................................................................................... 30 5. results and discussion ................................................................................................................................................................... 31 6. conclusion ......................................................................................................................................................................................... 36 references .............................................................................................................................................................................................. 37 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.28.37&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://www.asianonlinejournals.com/index.php/arees/article/view/1034 http://orcid.org/0000-0003-3425-9072 http://www.asianonlinejournals.com/index.php/arees/article/view/1034 http://orcid.org/0000-0003-3425-9072 http://www.asianonlinejournals.com/index.php/arees/article/view/1034 http://orcid.org/0000-0003-3425-9072 asian review of environmental and earth sciences, 2019, 6(1): 28-37 29 © 2019 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the present study was able contribute to the existing knowledge by providing some geological information and engineering properties of some basement rocks of southwestern nigeria, as aggregates in civil engineering construction especially pavements; since aggregates are principal materials in pavement construction which can take the form of either stabilized or unstabilized base or sub-base courses. the information is very crucial and pertinent to designing high quality roads in the study area. in addition the work would also be useful in selecting the rock types for quarry, for the production of aggregates for optimum use in sustainable highway construction. 1. introduction rock is one of the geomaterial used in construction in form of concrete, aggregate, building stone, and armourstone [1-4]. the suitability of rock for any civil engineering construction work depends on its physical property [5] and this is one of the basic goals of rock mechanics: to provide useful information and methods for predicting failure strength and associated parameters such as strain to failure and the effect of porosity and elastic moduli [6]. for ages rocks have been used as a construction material because it’s readily availability either in form of igneous, sedimentary, or metamorphic rock. although rocks requires little energy for extraction and processing. indeed, rock is used more or less as it is found except for the seasoning, shaping and dressing that is necessary before it is used for civil engineering construction purposes. however the volume of material that can be quarried; the ease with which it can be quarried [6] the wastage consequent upon quarrying; and the cost of transportation; as well as its appearance and physical properties [7, 8] are the determining factors whether a rock would reworked as construction material. also texture, appearance, porosity, durability [9-11] etc. are also desirable qualities of aggregates. crushed rock is produced for a number of purposes, the chief of which are for concrete and road aggregate [12-14]. approximately 75% of the volume of concrete consists of aggregate, therefore its properties have a significant influence on the engineering behaviour of concrete [12]. aggregate is divided into coarse and fine types, the former usually consisting of rock material that is less than 40 mm and larger than 4 mm in size. the latter is obviously less than 4 mm. fine types less than 75 mm should not exceed 10% by weight of the aggregate [12]; [15]. 2. literature review aggregate constitutes the basic material for road construction and is quarried in the same way as aggregate for concrete [16, 17]. because it forms the greater part of a road surface, aggregate has to bear the main stresses imposed by traffic, such as slow-crushing loads and rapid-impact loads, and has to resist wear. therefore, the rock material used should be fresh and have high strength [12]; [18, 19]. in addition, the aggregate used in the wearing course should be able to resist the polishing action of the traffic. the properties of road aggregate are related to the texture and mineralogical composition of the rock from which it was derived. most igneous and contact metamorphic rocks meet the requirements demanded of good roadstone [15]; [20]. on the other hand, many rocks of regional metamorphic origin are either cleaved or schistose and are therefore unsuitable for roadstone. this is because they tend to produce flaky particles when crushed. such particles do not achieve good interlock and, consequently, impair the development of dense mixtures for surface dressing. the amount and type of cement and/or matrix material that bind grains together in a sedimentary rock influence roadstone performance. the shape of aggregate particles is an important property and is governed mainly by the fracture pattern within a rock mass. the surface texture of aggregate particles largely determines the strength of the bond between the cement and themselves. a rough surface creates a good bond, whereas a smooth surface does not. many researchers [21-24] have tremendously contributed to knowledge in the aspects of compositional features and petrotectonic significance of quartzite and quartz-schist. studies on the compressive strength of artificial composite rock materials in relation to their moisture content in malaysia [25] emphasized probable complex engineering challenges due to variation in the rock composition. akpokodje [26] studied certain rock aggregates for the nigerian basement rocks. his findings show that the aggregates are good engineering materials based on both compressive strength and water absorption characteristics. adebisi and adeyemi [27] confirmed the exclusive sensitivity of gneisses in south-west nigeria to moisture content among other properties. the present study tries to employ field disposition and more importantly, some basic physical/geotechnical properties of the rocks in northern part of ondo, southwestern nigeria to elucidate further on their usefulness in civil engineering construction especially in the area of concreting, and aggregates in pavement construction. 3. description of study area the study area is located within the northern part of ondo state, nigeria figure 1. the selected areas include owo, akoko, and ose. these areas are located within longitudes 5°20´e and 6°10´e and latitudes 6°30´n and 7°40´n. the area is accessible through the benin ifon highway, abuja lokoja highway and ado-akure highway. the study area has a topographical elevation varying from 40 m – 750 m above the sea level. the northern part of the study area is a rugged terrain (i.e. hilly) especially in akoko area [28]. the annual rainfall ranges between 1000 and 1800 mm, with a mean annual rainfall of 1500 mm, and average wet days of about 100. the mean annual temperature is between 21°c and 33°c with mean temperature of 24°c and mean humidity of 80% [29]. asian review of environmental and earth sciences, 2019, 6(1): 28-37 30 © 2019 by the authors; licensee asian online journal publishing group figure-1. location map of the study area. source: ministry of works and housing, ondo state, nigeria. the geology of study area falls within the southwestern basement complex figure 2 and consists of migmatite, granites, granodiorite, granite gneiss, fine grained quartzite, charnockite, pegmatite and quartzo-feldspathic veins, schist, and quartz schist. these rock types dominate owo and akoko areas, notably along owo – oba akoko, iwaro – akungba, akungba – supare, ikare, epinmi, sosan, oke agbe, and ido ani. the migmatite complex which is the most widespread basement rock in the area is mainly medium grained gneiss. they are strongly foliated rocks frequently occurring as outcrops. on the surface of these outcrops, severely contorted, alternating bands of dark and light coloured minerals can be seen. these bands of light coloured minerals are essentially feldspar and quartz, while the dark coloured bands contain abundant biotite. a small proportion of the area especially to the northeast, overlies the coarse grained granites and gneisses, which are poor in ferromagnesian minerals. these rocks are covered by regoliths with thickness variation across the town. sand, clayshale, limestone, grift, sandstone, shale, coal, sandstone, and mudstone dominated the southern parts. the sedimentary rocks/deposit is mainly of the post cretaceous sediments and the cretaceous abeokuta formation. 4. material and methods in total, eight rock samples were collected from different lithological units in the study area which include porphyritic granite, fine grained granite, migmatite, granite gneiss, quartz schist, granodiorite, charnockite, and quartzite figure 2 and labelled as s1 – s8. the sites where the samples were taken are shown in figure 3. their geotechnical properties which comprises moisture content determination, aggregate impact value (aiv), aggregate crushed value (acv), point load strength test, specific gravity, water absorption test, unconfined compression test, and direct shear strength test. the values of the presented rock properties were predominantly determined as an arithmetic average of two to five rock specimen tests. all laboratory tests were carried out in accordance with astm d– 2216 [30] and isrm [31] for physical properties such as density, porosity, void ratio, moisture content and water absorption of the samples. the aggregate impact value (aiv) and aggregate crushed value (acv) were prepared using bs 812: part 110-112 british standard institution 1377 [32]. isrm [31] is: 2386 – part -3 for specific gravity determination for coarse aggregate. porosity was measured by dividing the amount of water filling the pore spaces, deduced from weight of each sample by density of water at room temperature. void ratio was calculated based on the dry weight of each rock sample by subtracting one from the product of the sample volume and density, divided by the mass of the sample. density was estimated from the ratio of bulk mass of each sample to its bulk volume. the mass of each specimen was determined after drying to a constant mass at a temperature of 105° c for 24 hours, and allowing it to cool in the desiccator for about 30 minutes. the volume of each sample was measured from its dimension, while water absorption was calculated as percentage by weight of water absorbed in terms of oven-dried weight of each sample. all numerical data obtained from the measured physical properties were subjected to statistical analysis, including regression plots in order to establish the relationship between the measured physical properties. the unconfined compressive strength, direct shear strength, point load test were determined as outlined in isrm [33]. for point load, the corrected point load strength index, is(50) was calculated using equation 1. asian review of environmental and earth sciences, 2019, 6(1): 28-37 31 © 2019 by the authors; licensee asian online journal publishing group figure-2. geological map of the study area showing locations of sample collection. source: nigeria geological survey agency. ( ) ……………………………. (1) where: p = failure load. = equivalent core diameter. = (for axial, block lump test). a = w × d. w = minimal cross sectional width. d = minimal cross sectional distance. f = size correction factor. f = ( ) 5. results and discussion the results of the physical properties of the tested rock samples are summarized in table 1 and 2. the natural moisture content of rock samples varies from 0.15% in quartzite to 0.43% in granodiorite. the water absorption potential of the samples ranges between 0.27% (quartzite) and 0.82% (porphyritic granite). water content is one of the most important factors influencing rock strength. considerable research has been carried out to investigate rock strength under both dry and water saturated conditions. according to these results, the petrophysical properties of rocks decrease with increasing moisture. quartzite is a metamorphosed arenaceous rock with granulose texture. predominantly composed of quartz. quartzite is usually thought of as thermally metamorphosed rocks but regional metamorphism also produces them. the low moisture content of the quartzite could have as a result of degree of metamorphism which increases the mineral bonding, while the high water obtained in granodiorite may be attributed to their texture. the specific gravity of the samples is between 2.65 (granite) and 2.73 (granodiorite/charnockite). the relatively high values obtained for granodiorite and charnockite could attributed to their mineral composition, as they tend to contain less quartz but high ferromagnesian minerals which denser and heavier in weight. the values of specific gravity obtained correlated well with range of values for crystalline rocks as reported in anon [34] and blyths and freitas [35]. asian review of environmental and earth sciences, 2019, 6(1): 28-37 32 © 2019 by the authors; licensee asian online journal publishing group figure-3. various sites where representative samples of the rock units are collected. source: fieldwork, 2017. the water absorption of the rock samples varies from 0.27 for quartzite to 0.82 for porphyritic granite. however the values obtained for granite (approx. 0.5) and quartzite (approx. 0.3) are very close to those reported in bell [12] for roadstone properties of some common aggregate in table 3. the dry unit weight recorded for the rock units ranges from 26.59 (quartzite) to 27.04 kn/m³ (quartz schist), while porosity ranges between 0.18 (quartzite) – 0.46 (porphyritic granite). according to anon [34] in table 4, the rock samples can be regarded as high to very high rocks, since their dry unit weight is greater than 25kn/m3 (25 mg m-3). this is consistent with the determined density of metamorphic rocks [5]. the rock units are characterized by low porosity as their values are less than 1. this implies that they are compact and impervious in their natural states. rock porosity depends on not only the density of the solid matrix material, but also the density of pore fluids as well as saturation. the aggregate impact value (aiv) gives a relative measure of the resistance of the aggregate to sudden shock or impact. the particular purpose which an aggregate is meant to serve requires the aggregate to have a particular strength which is usually stated in the specification table 5. this test provides a method for measuring this strength. the values of aiv ranges from 11.2 (quartzite/granite gneiss) to 17.3 (charnockite). gneiss has a rough banding or foliation, in which pale coloured bands of quartz and feldspar lie parallel with bands or streaks of mafic minerals figure 3; the mafic minerals are mainly biotite, hornblende, or in some cases pyroxene. biotite is often accompanied by muscovite, and garnets are common accessory minerals. a gneiss breaks less readily than a schist and commonly splits across the foliation; it is often coarser in texture than most schists, though some gneisses are relatively fine-grained [35]. therefore based on this characteristics of gneiss, this might be responsible for low aiv recorded relative to other rock samples. from table 5, the rock units can categorized as strong aggregate in terms of quality for road pavement. these values of aiv of the rock samples correlate well with some rock units of the same lithology (granite and quartzite) reported by bell [12]. the aggregate crushing value provides a relative measure of resistance to crushing under a gradually applied compressive load. aggregate used in road construction should be strong enough to resist crushing under traffic wheel loads. if the aggregates are weak, the stability of the pavement structure is likely to be adversely affected. to achieve a high quality of asian review of environmental and earth sciences, 2019, 6(1): 28-37 33 © 2019 by the authors; licensee asian online journal publishing group pavement, aggregate possessing low aggregate crushing value should be preferred. the acv recorded a range of 18.4 (quartzite) – 25.2 (charnockite). the aggregate crushing value for road material; cement concrete pavement should not exceed 30%, while acv for wearing surfaces should not exceed 45%. therefore the rock units are very excellent as aggregate for road pavement construction. figure-4. pictures of some equipment and processes undertaken in the course of the laboratory analysis. source: federal university of technology, akure, nigeria. the point load strength test is used as an index test for strength classification of rock materials. the test method is performed to determine the point load strength index ( ) of rock specimens. the point load strength index (plsi) of the samples ranges between 7.40 and 9.87. charnockite is characterized with relatively high plsi of the sampled rocks. the charnockite obtained in the study area are fine to medium-grained, equigranular and massive, sometimes porphyritic. charnockitic rocks constitute one of the important petrological units within the precambrian basement complex of nigeria. they are generally characterized by their dark greenish to greenish grey appearance which makes them easily recognizable in hand specimen. they usually contain quartz + plagioclase + alkali feldspar + orthopyroxene + clinopyroxene + hornblende ± biotite ± fayalite. accessory minerals are usually zircon, apatite, and iron ores [36, 37]. therefore high value of plsi observed in the charnockite could be as a result of its texture and chemical composition. hence based on table 6 according to franklin and broch [38] the rocks can be categorized as very high strength rock materials with corresponding compressive strength between 50 and 160 mpa, which correlates with the actual values obtained for the sampled rocks i.e. 121 – 185.3mpa. subsequently using table 7 and 8, according to geological society, international association of engineering geologist and international society for rocks mechanics, they are very strong rock units. asian review of environmental and earth sciences, 2019, 6(1): 28-37 34 © 2019 by the authors; licensee asian online journal publishing group table-1. summary of the physical properties of sampled rocks. sample no. rock unit mc (%) aiv acv plsi (mpa) sg wa (%) ucs (mpa) st (mpa) s1 porphyritic granite 0.41 15.2 24.2 7.40 2.65 0.82 121.1 60.5 s2 granite 0.39 13.1 23.1 8.08 2.69 0.48 143.1 71.6 s3 migmatite 0.34 14.4 23.1 8.05 2.66 0.57 122.1 61.1 s4 granite gneiss 0.38 11.2 19.7 8.82 2.70 0.33 127.5 63.7 s5 quartz schist 0.24 12.4 22.2 8.89 2.66 0.66 159.4 79.7 s6 granodiorite 0.43 12.1 21.1 9.52 2.73 0.44 170.2 85.1 s7 charnockite 0.34 17.3 25.2 9.87 2.72 0.47 165.9 82.9 s8 quartzite 0.15 11.2 18.4 8.84 2.65 0.27 185.3 92.6 note: mc-moisture content, aiv-aggregate impact value, acv-aggregate crushed value plsi-point load strength index, wa-water absorption, ucsunconfined compressive strength, st-shear strength. table-2. results of the dry unit weight, porosity, and water content of the rock samples. sample no. rock unit dry unit wt. (kn/m³) porosity (%) water content (%) s1 porphyritic granite 26.72 0.46 0.16 s2 granite 26.82 0.37 0.23 s3 migmatite 26.90 0.37 0.15 s4 granite gneiss 26.71 0.38 0.29 s5 quartz schist 27.04 0.29 0.12 s6 granodiorite 27.03 0.30 0.22 s7 charnockite 26.79 0.31 0.19 s8 quartzite 26.59 0.18 0.11 table-3. some representative values of the roadstone properties of some common aggregates. rock type water absorption specific gravity aggregate crushing value aggregate impact value basalt 0.9 2.91 14 13 dolerite 0.4 2.95 10 9 granite 0.8 2.64 17 20 micro-granite 0.5 2.65 12 14 hornfels 0.5 2.81 13 11 quartzite 1.8 2.63 20 18 limestone 0.5 2.69 14 20 greywacke 0.5 2.72 10 12 source: after bell [12]. table-4. dry density and porosity. class dry density (mg m-3) description porosity (%) description 1 less than 1.8 very low over 30 very high 2 1.8-2.2 low 30-15 high 3 2.2-2.55 moderate 15-5 medium 4 2.55-2.75 high 5-1 low 5 over 2.75 very high less than 1 very low source: after blyths and freitas [35]. the shear strength of the samples varies from 60.5 (porphyritic granite) to 92.6 mpa (quartzite). quartzite is derived from the conversion of siliceous rock such as sandstone through the process of metamorphism. the original quartz grains of the sandstone (and siliceous cement if present) are recrystallized as an interlocking mosaic of quartz crystals. therefore quartzite in its massive, unweathered state is very strong, in terms of crushing and shear strengths. figures 6-11 show regression plots of the physical parameters measured. porosity, water absorption, specific gravity (sg), and moisture content (mc) are chosen as independent variables, while shear strength (ss), unconfined compressive strength (ucs), aiv, acv, and plsi are dependent variables. figure 4 shows fair positive relationship (r2 = 0.4078) between wa against p. ss and usc have a high positive coefficient of correlation with porosity i.e. r2 = 0.8291; 0.8287 respectively figure 5 and 6. low positive correlation coefficient exists between ucs and mc (0.31); aiv and wa (0.25); aiv and p (0.15); acv and p (0.32). however acv shows a fair positive correlation with wa (r2 = 0.4815), while plsi recorded a good correlation coefficient of 0.5 with specific gravity figure 11. therefore from the regression analysis plots, porosity and specific gravity are the major properties that show strong positive correlations with shear strength, unconfined compressive strength, and point load strength index [39]. table-5. classification of aggregate based on aggregate impact value. aiv (%) quality of aggregate <10 exceptionally strong 10-20 strong 20-30 satisfactorily for road surfacing >35 weak for road surfacing source: thuro and plinninger [39]. asian review of environmental and earth sciences, 2019, 6(1): 28-37 35 © 2019 by the authors; licensee asian online journal publishing group table-6. point load strength classification. class point load strength index (mpa) equivalent uniaxial compressive strength (mpa) extremely high strength over 10 over 160 very high strength 3-10 50-160 high strength 1-3 15-60 medium strength 0.3-1 5-16 low strength 0.1-0.3 1.6-5 very low strength 0.03-0.1 0.5-1.6 extremely low strength less than 0.03 less than 0.5 source: after franklin and broch [38]. table-7. classification of compressive strength of rocks. class compressive strength (mpa) term 1 over 200 extremely strong 2 100-200 very strong 3 50-100 strong source: after anon [40]. table-8. grades of unconfined compressive strength. geological society, anon [40] iaeg [34] isrm [41] term strength (mpa) term strength (mpa) term strength (mpa) very weak less than 1.25 weak under 15 very low under 6 weak 1.25-5.00 moderately strong 15-50 low 6-10 moderately weak 5.00-12.50 strong 50-120 moderate 20-60 moderately strong 12.50-50 very strong 120-230 high 60-200 strong 50-100 extremely strong over 230 very high over 200 very strong 100-200 extremely strong over 200 source: after anon [41]. figure-5. regression plot of water absorption against porosity. source: data analysis. figure-6. regression plot of shear strength against porosity. source: data analysis. figure-7. regression plot of unconfined compressive strength (ucs) against porosity. source: data analysis. asian review of environmental and earth sciences, 2019, 6(1): 28-37 36 © 2019 by the authors; licensee asian online journal publishing group figure-8. regression plot of ucs against moisture content. source: data analysis. figure-9. regression plot of aggregate impact value and aggregate crushing value against water absorption. source: data analysis. figure-10. regression plot of aggregate impact value and aggregate crushing value against porosity. source: data analysis. figure-11. regression plot of point load strength index and against specific gravity. source: data analysis. 6. conclusion the degree at which rocks can be used as building stones, armourstone, aggregate in pavement construction, and concrete depends on physical properties, which is a reflection of compositional features. in order to achieve this parameters such as moisture content, dry density, porosity, specific gravity, aggregate impact value, aggregate crushing value, point load strength index, unconfined compressive strength, and shear strength were determined from eight different lithological rock units. findings show that the rocks are characterized by low porosity, very high strength on the basis of point load strength index and shear strength. the samples show strong quality as aggregate in pavement construction. however charnockite seems to have excellent physical properties which could attributed to its texture and mineral composition. it is also observed that porosity and specific gravity are the major parameters that show strong positive correlations with important geotechnical parameters such as shear strength, unconfined compressive strength, and point load strength index. asian review of environmental and earth sciences, 2019, 6(1): 28-37 37 © 2019 by the authors; licensee asian online journal publishing group references [1] a. b. hawkins, "geomaterials in construction: an introduction," quarterly journal of engineering geology, vol. 24, pp. 1-2, 1991. [2] w. j. french, "introduction: applied petrology – the stability of concrete aggregates," quarterly journal of engineering geology, vol. 13, p. 205, 1980. [3] a. r. clark and j. s. palmer, "the problem of quality control and selection of armourstone," quarterly journal of engineering geology, vol. 24, pp. 119-122, 1991. available at: https://doi.org/10.1144/gsl.qjeg.1991.024.01.12. [4] p. g. fookes, "geomaterials," quarterly journal of engineering geology, vol. 24, pp. 3-15, 1991. [5] d. p. krynine and w. r. judd, principles of geotechnics and geology, 1st ed. new delhi, india: mcgraw hill, 1958. [6] f. ighrakpata, o. molua, e. igherighe, and j. idialu, "comparison of the strength of two different rock samples," the pacific journal of science and technology, vol. 13, pp. 384-390, 2012. [7] a. yavuz, n. turk, and m. koca, geological parameters affecting the marble production in the quarries along the southern flank of the menderes massif, in sw turkey. engineering geology, vol. 80, pp. 214-241, 2005. available at: https://doi.org/10.1016/j.enggeo.2005.05.003. [8] d. jefferson, "building stone: the geological dimension," quarterly journal of engineering geology and hydrogeology, vol. 26, pp. 305319, 1993. available at: https://doi.org/10.1144/gsl.qjegh.1993.026.004.06. [9] a. arizzi and g. cultrone, "the influence of aggregate texture, morphology and grading on the carbonation of non-hydraulic (aerial) lime-based mortars," quarterly journal of engineering geology and hydrogeology, vol. 46, pp. 507-520, 2013. available at: https://doi.org/10.1144/qjegh2012-017. [10] t. e. dibb, d. w. hughes, and a. b. poole, "controls of size and shape of natural armourstone," quarterly journal of engineering geology, vol. 16, pp. 31-42, 1983a. available at: https://doi.org/10.1144/gsl.qjeg.1983.016.01.03. [11] t. e. dibb, d. w. hughes, and a. b. poole, "the identification of critical factors affecting rock durability in marine environments," quarterly journal of engineering geology, vol. 16, pp. 149-161, 1983b. available at: https://doi.org/10.1144/gsl.qjeg.1983.016.02.08. [12] f. g. bell, engineering geology. jordan hill, oxyford, united kingdom: elsevier ltd, 2007. [13] j. bullas, "modification of the formula used in the determination of the ten per cent fines value of aggregate," quarterly journal of engineering geology, vol. 23, pp. 187-188, 1990. available at: https://doi.org/10.1144/gsl.qjeg.1990.023.02.07. [14] i. b. cameron, "wearing course aggregates in northern ireland," quarterly journal of engineering geology, vol. 5, pp. 81-83, 1972. available at: https://doi.org/10.1144/gsl.qjeg.1972.005.01.09. [15] p. fookes, "an introduction to the influence of natural aggregates on the performance and durability of concrete," quarterly journal of engineering geology and hydrogeology, vol. 13, pp. 207-229, 1980. [16] i. sims, "quality and durability of stone for construction," quarterly journal of engineering geology and hydrogeology, vol. 24, pp. 6773, 1991. available at: https://doi.org/10.1144/gsl.qjeg.1991.024.01.06. [17] i. sims, "sand, gravel and crushed rock aggregates for construction purposes: geological society engineering group working party," quarterly journal of engineering geology and hydrogeology, vol. 19, pp. 325-338, 1986. available at: https://doi.org/10.1144/gsl.qjeg.1986.019.03.13. [18] i. collis and r. a. fox, geological society, aggregates: sand, gravel and crushed rock aggregates for construction purposes (eds. i. collis and r.a. fox) vol. 1: engineering geology special publication, 1985. [19] j. p. latham, geological society, advances in aggregates and armourstone evaluation (ed. j.-p. latham): engineering geology special publication, 1998. [20] p. fookes and a. poole, "some preliminary considerations on the selection and durability of rock and concrete materials for breakwaters and coastal protection works," quarterly journal of engineering geology and hydrogeology, vol. 14, pp. 97-128, 1981. available at: https://doi.org/10.1144/gsl.qjeg.1981.014.02.03. [21] c. okonkwo, "structural geology of basement rocks of jebba area, nigeria," journal of mining and geology, vol. 28, pp. 203-209, 1992. [22] c. okonkwo, "geochemistry of quartzites and quartz-mica schist in jebba area, nigeria," journal of mining and geololgy, vol. 28, pp. 203-209, 2005. [23] c. t. okonkwo and j. a. winchester, geochemistry of semi-pelitic schist konga area, northwestern nigeria. global journal of pure and applied sciences, vol. 7, pp. 303 – 309, 2001. available at: https://doi.org/10.4314/gjpas.v7i2.16249. [24] a. a. elueze and o. a. okunlola, petrochemical and petrogenetic characteristics of metasedimentary rocks of lokoja – jakura schist belt, central nigeria. journal of mining and geology, vol. 39, pp. 163 – 173, 2003. available at: https://doi.org/10.4314/jmg.v39i1.18787. [25] z. mohamed, k. mohamed, and c. g. chun, "uniaxial compressive strength of composite rock material with respect to shale thickness ratio and moisture," electronic journal of geotechnical engineering, vol. 13, pp. 1-10, 2008. [26] e. akpokodje, "properties of some nigeria rock aggregates," journal of mining and geology, vol. 23, pp. 185-190, 1992. [27] n. o. adebisi and g. o. adeyemi, "compressive strength properties of gneisses in southwestern nigeria," quarterly publication of scientific society of mineral wealth technology geotechnology, vol. 156, pp. 43-50, 2001. [28] r. w. marans and w. rodgers, toward an understanding of community satisfaction: in hawley a.h. and rock v.p. (eds), metropolitan america in contemporary perspective. london: wiley publishing, 1975. [29] n. p. iloeje, a new geography of nigeria. lagos: longman nig. ltd., 1981. [30] astm d– 2216, american standards for testing and materials – standard test methods for laboratory determination of moisture content of soil and rock. west conshohocken, pa: astm international, 1992. [31] b. e. isrm, suggested methods: rock characterization, testing and monitoring. pergamon, oxford: isrm commission on testing methods, 1981. [32] british standard institution 1377, methods of test for soil for civil engineering purposes. london: bs1377, 1990. [33] j. franklin, "suggested method for determining point load strength," international journal of rock mechanics and mining sciences, vol. 22, pp. 53-60, 1985. available at: https://doi.org/10.1016/0148-9062(85)92985-7. [34] o. anon, "classification of rocks and soils for engineering geological mapping. part 1: rock and soil materials," bulletin of the international association of engineering geology, vol. 19, pp. 355-371, 1979. available at: https://doi.org/10.1007/bf02600503. [35] f. g. h. blyths and m. h. d. freitas, a geology for engineers, 7th ed. jordan hill, oxyford, united kingdom: edward arnold, elsevier butterworth-heinemann, 1984. [36] v. o. olarewaju, the charnockitic intrusives of nigeria. in: oshi o (ed), the basement complex of nigeria and its mineral resources (a tribute to prof. m. a. o. rahaman). ibadan: akin jinad & co, 2006. [37] n. g. obaje, geology and mineral resources of nigeria. london new york: springer dordrecht heidelberg, 2009. [38] j. l. franklin and e. broch, "the point load test," international journal rock mechanics and mining science, vol. 9, pp. 669–697, 1972. [39] k. thuro and r. j. plinninger, scale effects in rock strength properties. part 2: point load test and point load strength index. rock mechanics – a challenge for society, särkkä & eloranta (eds.): swets & zeitlinger lisse, 2001. [40] q. anon, "the description of rock masses for engineering purposes," journal of engineering geology, vol. 10, pp. 355-388, 1977. [41] o. anon, "basic geotechnical description of rock masses. international society of rock mechanics commission on the classification of rocks and rock masses," international society of rock mechanics and mining sciences and geomechanical abstracts, vol. 18, pp. 85-110, 1981. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 2, 23-34, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 23 environmental impact assessment and sedimentology of the carbonate quarry site for al-maroua'ah cement plant in al-hodeida district, nw yemen sa'ad zeki a. kader al-mashaikie 1* --abdul-kader mohammed al-karraz 2 1, dept. of geology, collage sciences, baghdad university, al-jadryiah, baghdad, iraq 2, dept. of marine environment, faculty of marine & environmental sciences, al-hodiedah univ. al-hodiedah, yemen abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 24 2. methods and materials ............................................................................................................................................................. 24 3. quarry site and characterization ........................................................................................................................................... 24 4. description of the natural environment ................................................................................................................................. 26 5. ambient air quality and levels of noisiness ......................................................................................................................... 27 6. potential environmental impact .............................................................................................................................................. 28 7. type of air pollution................................................................................................................................................................. 28 8. weather and topography ........................................................................................................................................................ 28 9. dispersion modeling system .................................................................................................................................................... 28 10. limitations ............................................................................................................................................................................... 30 11. environmental mitigation plan ............................................................................................................................................. 31 12. conclusion ................................................................................................................................................................................ 33 references ...................................................................................................................................................................................... 33 in this study, environmental impact assessment and sedimentology includes chemical analysis were carried out for the quarry site of the limestone raw material in al-maroua'ah cement plant in tehama plane, al-hodeida district nw yemen. the study includes the assessment of the limestone raw materials, the quality, chemical and mineralogical analysis and expected pollutions impact in the quarry site. the studied rock successions are belonging to the amran group, which is composed mainly of limestone rocks with few interbedded marl, shale and sandstone beds. the chemical analysis of the limestone rocks show cao content is (50.31%), with very little mgo content (0.71%). the present shale marl and sandstone rock units are useful for the correction of the rocks to concise with the international specifications of the cement production. the site of the quarry of the main raw materials of limestone rocks was selected far from the villages and human populations to prevent the environmental pollutions according to the who and yepa specifications. the emitted dust from the operations of the quarry machine makes impacts on the surrounding environments especially for the farms and the natural plants and animals, which are living in the region. for this, the site of quarry is selected in a mountain far from the vegetation, population and villages to avoid the expected environmental impact. mitigation plan for prevent or decreases the pollution impact to the minimum, was discussed. keywords: al-maroua’ah, eia, limestone, quarry, chemical analysis, dust pollution, gases pollution, management plan. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(2): 23-34 24 1. introduction al-maroua’ah cement factory is significantly contributed in the development of the yemeni economy after operating in early 2015. the plant management had adopted the commitment to improve the local economy of alhodiedah governorate, and the region where the plant exists, to provide jobs for the citizens of the governorate and of the region in particular, in addition to the medical and educational services proposed to be provided in the plant region, as well as the erection of the integrated residential city for the staff and the labors of the plant. the cement production capacity in al-maroua’ah cement factory reaches up to 3,000,000 mt of cement. this study had been produced to assess the environmental impacts of the operations held in the quarry of the raw materials and the resulting residuals of such operations followed the limitation of the epa [1]. the plant management undertakes to apply the yemeni environment management plans proposed in this study; including the measures of reducing the emissions; and the continuous environmental monitoring program. moreover, this study deals with the assessment of the carbonate rocks as the main raw materials in cement production. 2. methods and materials the evaluation of the quarry and the raw materials for cement production and its environmental impact includes field works and survey as well as chemical analysis. the field works include the selection of the quarry site according to the international specification to prevent the environmental pollution as well as the systematic sampling of the limestone raw materials for quality evaluation. it will exploit the falafel mountain to supply the factory for raw materials (limestone). the ei assessment was followed the parameters listed in the epa [1] and national [2] falafel mountain was divided into three areas for exploit and the details of these areas and coordinates are listed in figure 1. twenty five (25) rock samples were collected and later prepared and analyzed by xrf in the lab of alwatanyiah cement plant in lahg governate followed the procedure listed in tucker [3]. the results were interpreted and the rocks were evaluated for cement production. 3. quarry site and characterization the quarry site is lying in jabal falafel mountain in al-maroua’ah region, 36 km east of al-hodiedah governorate, and 4-5 km from the main road connect al-hodiedah with sana’a city (fig.1). jabal falafel mountain lies near dear daood village, which is situated in tehama plane parallel to the coast of the red sea. some of these areas are agricultural farms with abundant underground water in all seasons of the year. the land surface of the region is located at an elevation of about 120 meters above the sea level (fig.1) the primary raw materials used in the production of cement are usually provided from limestone quarries, which are generally located near the plant site to reduce transportation and production costs, whereby the limestone bedrocks are the most important imperative raw materials for cement industry. the limestone rocks are extracted by drilling and explosion before being transported by conveyor belts or heavy trucks. later on, the extracted rocks are subjected to cracking and screening processes to specify the grain size, and finally stored [4]. the heavy trucks working in the quarry discharge the cargos in the funnel-shaped container (hopper), which is supported by series of sieves to separate pieces of large from the smaller rocks, thereby curtailing the load and effort of the initial crusher. the large rocks are broken down and the sizes are reduced (size of product 90% less than 25mm) before passing over conveyor belt which transfers the raw materials through gamma automatic analyzer, and thereafter, they store in opened sheds yard [4, 5]. 3.1. sedimentology and quality of the limestone the limestones is belonging to amran group and cropping out in jabal falafel mountain, which is laying near the site al-maroua’ah cement plant. the carbonate rocks include successive and interbedded massive and bedded limestone and marls of about 500 m thick [6]. thick massive sandstone bed of 25 m thick is interbedded with limestones. the limestones are composed of lime mudstone, packstone, grainstone and wackestone microfacies flugel [7] and scholl and ulmer-scholl [8]. it is mainly composed of calcite and micrite, with very rare dolomites, which represents very good quality for cement production [4, 5]. the sandstone is basically composed of silica grains and partial cemented with argillaceous matrix. 3.2. chemical analysis the chemical analysis was carried out using xr-fluorescence instrument type thrmo in the lab of alwatanyiah cement factory and the data is listed in table (1) which shows that is relatively pure with high to very high cao% and low mgo%. the silica, aluminum, iron oxides and alkalis are very low. thus, the raw materials require substantial correction with argillaceous, siliceous and ferruginous materials. asian review of environmental and earth sciences, 2015, 2(2): 23-34 25 fig-1. location map of yemen shows the site of al-maroua’ah cement plant and the quarry site (the colored blocks), at jabal falafel mountain (sat image-google earth). fig-2. field photograph shows the extraction processes of limestone table-1, shows the chemical analysis data of the limestone and other raw materials in the study area. asian review of environmental and earth sciences, 2015, 2(2): 23-34 26 4. description of the natural environment topography of the site is located at height of about 120 m and the mountains altitudes around is reaching 400 m height a.s.l. and 300 m above land surface .the area is gradually sloping towards the west and expands in all directions as wide planes extends for hundreds of kilometers [9]. 4.1. climate and water metrology the tehama region is of arid climate, extremely hot during winter months (november to march) when temperatures range from 20c 0 to 30c 0 . the mean monthly maximum temperatures are ranging from 32c 0 in january to 39c 0 in june. annual precipitation is 100 mm in the costal line to 400 mm near the foothills and mountains, most of which occurs in april to october. the annual evapotranspiration is about 1864 mm/year. the region is characterized by high relative humidity with average of 71-76 %. the wind in tehama plane (includes al-maroua’ah area) is of southern general direction (table.3). the annual average values of sunshine in al-hodiedah governorate range between 7 to 10 h/day, which correspond to 50 to 75 % of the theoretical maximum. the monthly sunshine duration in al-hodiedah governorates ranges from 7 h/day in july to 10 h/day in november. 4.2. biology and agriculture farms many types of trees are considerably proliferating in the mountains surrounding the factory site. the agricultural fields are spreading down on the lands surrounding falafel mountain, which sometimes expands to distance more than 2 km. corn and vegetables cultivation as well as mango farms are widely spread throughout the valleys (pl/1, a, b, c). 4.3. natural environments in almaroua’ah area represents one of mountainous regions, which includes relatively high biodiversity and provides significant habitat for the birds and their migration to other regions. most of native and semi-origin animals and plants exist in the study area, such as: hemitragus jayakari, the arabian gazelle (gazella gazelle), the mountainous caribou (capra ibex nubiana), the striped hyaena (hyaena), the wild cat (felis sylvestris) and the panther (panthera xanthopygos). the types of the birds exist in the region are yellow-incision nightingale (pycnonotus xanthopygos), songbird (prinia gracilis), brown songbird (phylloscopus umbrovirens), yemeni apple bird (carduelis yemenensis), dark skin flycatcher bird (muscicapa gambagae), arab partridge (alectoris melanocephalia), and black shuhite bird (milvus migrans) [2, 10]. falafel mount is a barren area in which do not grow any plants, but there are some trees from acacia type (pl/1, d). 4.4. human populations in the republic of yemen had a high population growth ratio reaches 3.5% in the recent decades. this immense population expansion created certain risk to the scarce environmental system and threatened the great biodiversity and the bio-natural fortune in the country. 4.5 water resources come from rain-fed, which is inadequate in all districts of northern tehama except for dry cropping where low rainfall is about 50% below evapotranspiration rate during the most days of the year. consequently, groundwater is the main and supplementary source of irrigation . impact of overexploitation of deep aquifers results in depletion of groundwater table from 1-7 m/year. sources of irrigation in al-hodiedah governorate are shown in (table. 2). it is unexpected to note that groundwater in irrigated area was retreated in 2004 to 2008 despite the lack of control measurement for the resource [2, 11, 12]. table-2. shows cropped area by sources of irrigation, al-hodiedah area. source: [11-13]. table-3. meteorological data of al-hodiedah district from 1995 to 2008. source: fao [14] asian review of environmental and earth sciences, 2015, 2(2): 23-34 27 plate-1. field photographs show the plant diversity in the agriculture farms and natural trees in jabal falafel mountain. a. the corn farms near al-maroua'ah site of the cement plant. b. the mango trees near al-maroua'ah site of the cement plant. c. the wide extended agriculture farms in the vicinity of al-maroua'ah plant site. d. the acacia natural trees in the vicinity of al-maroua'ah plant site. 5. ambient air quality and levels of noisiness most regions in the republic of yemen do not possess scientific data about the air quality and levels of noise. in this study, efforts were exerted to collect database upon air quality and levels of noise in the region of al-maroua’ah cement plant. it is worth mentioning that this region is situated 5 km from the main road connect sana'a and alhodiedah cities and far from villages, noisiness and crowded people and markets. al-maroua’ah area is characterized by proliferation of agricultural lands on both sides of the mountain, where the people is working in agricultural and the fields of cattle breeds and sheep herding. no air pollutant was found, while the vehicles traffic is few, quiet life atmosphere is prevailing and population density is low (table 4). the data of the air quality and dust concentrations in al-maroua’ah area is lying within the limits of the standards of eu [15] aaep [16] epa [1] and (table.5). air pollution comes from operating of the quarry machines (shovels, trucks and crushers), which produced dust, carbon dioxide and associated gases. production of 3000 tons/day cement creates pollution of dust and co2 gas emitted to the surrounding environments e.g. natural and agriculture plants as well as animals and people. the pollution is coming from; (1) explosions of dynamite in the quarry, (2) shovels transport the raw materials to the main crusher, (3) viechels and trucks transport the raw materials. three types of crushers are operating to crush the limestone raw materials to smaller size and produce two essential types of impact; dust and gases in the air, and noises. table-4. collected data of dust concentrations in the air of certain localities in al-maroua’ah cement plant site in the morning (in field work). table-5. proposed standards in view of air quality [1, 15, 16]; asian review of environmental and earth sciences, 2015, 2(2): 23-34 28 6. potential environmental impact the potential environmental impacts are resulted from different stages of operation of al-maraoua'ah cement factory. the important pollutions include air, surface and ground waters, soil, biodiversity, methods of utilizing of the natural resources, health and safety factors, impact on the landscapes, social and economic indices in the region. assessment of impacts is determine using quantitative uses of the analytical equipment's and computing methods, while other pollution can be identified in term of the qualitative comparison and description in accordance with the previous observations [17, 18]. consequently, assessment of the environmental pollution impacts is directly linked to the definition of those locations, which may be exposed to pollution, including local areas, hospitals, residential areas, schools, offices, factories, commercial shops, mosques, sports stadiums and recreation places. it is worth emphasizing that the site of the project is located in rural agricultural area, where villages and agricultural farms are distributed in the region, with absence of cities, public governmental or private facilities. the locations which are exposed to pollution and close to the plant site are the surrounding villages, the residential units which shall be erected for the plant labors and staff, and the agricultural fields (fig. 3; table.6). 7. type of air pollution this study focus on the assessment of the anticipated environmental impacts in terms of kinds of the air pollution, which may appear during the quarry processes and mainly resulting from the smelting operations of raw and grinded materials to produce 3,000,000 t/y of clinker in al-maraoua'ah cement plant. it is well known that the quarry process of the raw materials is characterized by emission of immense quantities of dust and gases; which are generated due to the explosion of dynamites and the primary and secondary crushing and grinding of the limestone raw materials near the quarry. moreover, the operations of the shovels, viechels and machines are emitted real quantities of carbon dioxide and associated gases, which are pollute surrounding areas. the grinding of limestones to finer size, leads to inevitably significant emissions of dust. the size and composition of the emitted dust particles mainly depend upon the characteristics of the primary raw materials. (table 6) table-6. types of the emitted dust and the reasons of the formation during different processes [19]. 8. weather and topography data of weather conditions and terrain are forming important input indices of impact of the dispersion of dust and gases emissions from the quarry source in open spaces. changes in weather conditions and topography may lead to change in the levels of concentrations at the exposure sites. hence, it is required to obtain hourly data on weather conditions during the year. the inserted data in the program is collected from the city of al-hodiedah, which enjoys weather conditions similar to those of al-maroua’ah area, where the air monitoring stations do not exist in the study area. al-maroua’ah area comprises simple topography, which lies in flat plane with scattered medium height mountains. the altitudes of the topography were calculated in the field survey and google earth utility through the international information network (internet) and using program gis and dem 90m for earth (nasa.usa). this survey indicates that the height of the ground surface of the site is 120 m and the mountains are 365 m and 400 m. there is important to classify the utilization of lands in the vicinity of al-maraoua'ah cement site, considering that the average dispersion is variable between the rural environment and the urban environment follow the general outlines of the usepa [15, 18]. epa is relevant to the air quality simulation programs depending on the factors of population density and land utilization methods as standards of classification. it is advised to apply the dispersion indices belonging to the rural environment. the site of the cement plant is located in agricultural region and occupies an area of 5 km 2 , where any kinds of industrial facilities do not exist. hence, the rural environment indices were selected to apply, considering that the vicinity surrounding the site has low population density and agricultural vicinity. 9. dispersion modeling system gis modeling using potential data is applying for annual pollution, which is plotted on topographic map of the area include villages and the cement plant site fig.6.5, 6.6. breeze isc gis pro version 4.1.3model was used with more accurate data, which is developed according to the model of usepa united states environmental protection agency [20] to assess the environmental impact of the dust and gases emissions. 9.1. dispersion of dust the adopted interpretative of illustrate the levels of concentrations are shown in table 5.10. in the absence of the control the pollution of potential emissions in the cement plant, wide area is exposed to emission levels exceed the health standards that permits by the epa [1] in terms of dust concentration. asian review of environmental and earth sciences, 2015, 2(2): 23-34 29 fig-3. shows the dust emission from the sources of the open spaces in the quarry site. table-6.6. proposed emission data produces from the sources of the open spaces in the cement plants. table-6.9. shows the approval probabilities in specify dispersion of emissions. fig-6.5. annually pm exposure levels in proposed production capacity of 3,000,000 tons/year (bat: best available technology). note the wind direction is pointed in the lower right edge of the photo. asian review of environmental and earth sciences, 2015, 2(2): 23-34 30 fig-6.6. annually pm exposure levels under proposed production capacity of 2,000,000 tons/year (bat: best available technology). note the wind direction is pointed in the lower right edge of the photo. 10. limitations several limitations were encountered in the present study. the absence of reliable and long-term site-specific data, which is required drawing on literature reported values that may not accurately describe the actual operational conditions at neither mcp nor the baseline environment in al-maroua'ah area. as such, it is imperative to implement suggested monitoring program and to reassess the results and validate the simulated exposure levels based on long-term and systematic monitoring data. the available models are far from being ideal and are simplifications of reality. models are only capable of providing rough overview of real time processes and are best used for comparison purposes. note also that all air dispersion models including isc exhibit increasing uncertainty with short-term average periods. this uncertainty decreases with increase average periods and as such predicted annual exposure levels tend to be more accurate than daily levels. 10.1. noise and vibrations noise is defined as “unwanted sound”. it has numerous adverse effects on people’s health as well as environment. several factors other than the magnitude of exposure typically influence community reaction to noise including duration of intruding noises and frequency of occurrence, time of year (windows open or closed), time of day of noise exposure, outdoor noise level in community when intruding noises are not present, history of prior exposure to noise source, attitude towards noise source, and presence of pure tones and impulses [18]. activities of quarry heavy machineries are generate high levels of noise, much of which can be reduced by properly sitting and insulating the operations area [21]. noise generation from the cement industry may either be permanent or intermittent. intermittent noise is mainly due to blasting, the daily starting of engines, and the loading of rocks into dumpers [22]. permanent noise generating sources can be divided into three main groups after [23]: dynamite explosion of the raw materials machine generated noise e.g. shovels, tracks, digging compressors and crushers. generally, the type and age of machines affect the level of noise generated. the older machines are usually emitting higher levels of noise. trucks and conveyers that transported the raw materials from the quarry to the plant site the assessment of the noise impacts resulting from the operation of the mcp plant under the current production capacity of 3,000,000 tons /year using two digital sound level meters (fig. 6.9). measured levels conformed to typical energy-equivalent noise levels that have been reported for the cement industry. the resulting noise levels exceed both daytime and nighttime yemeni noise standards set forth for rural and suburban residential areas, while the standard set forth for industrial areas is achieved within 2 km radius. l l 20log (x 250) 48 (1) the noise action on-site are of concern to on-site workers who are exposed to elevated noise levels for an average period of 8-hr. most measured noise levels are exceeding the occupational safety and health administration (osha) 8-hour occupational noise exposure standard of 90 (dba). asian review of environmental and earth sciences, 2015, 2(2): 23-34 31 vibrations on the other hand, are produced by blasting of limestone quarry and from heavy traffic on or off-site. the levels of generated vibration are generally below those that cause structural damage to properties. however, vibrations transmitted through the ground and pressure waves through the air (“overpressure”) shake buildings and may create nuisance. in this context, blasting is an issue of concern for the local people. for several residential units surrounding mcp, have complain that vibrations from the plant have result in property damage. fig-6.9. proposed noise meters used at mcp to measure ambient and industry related noise levels. table-6.13. show measurement of noise levels at mcp compared to typical energy-equivalent noise levels reported for the cement industry [22] nr: not recorded 1: measured at 7.5 m from source 2: value measured during the loading and transport of raw materials 11. environmental mitigation plan the primary potential adverse environmental impacts associated with the operations in mcp can be minimized by careful planning, adopt proper management practices, and relying on effective environmental monitoring. the mitigation plan suggests several potential impact-mitigation or control measures that will earn mcp more acceptability by eliminating or reduce the possible extent of impacts and intended to reduce the effect of potentially significant impacts on the environment. they are highly dependent on the significance of the predicted and the nature of the impact (permanent vs. temporary). 11.1. mitigation of air quality impact several mitigation measures are available to reduce the diverse environmental impacts that ambient air quality. these measures are compound specific and vary in the treatment efficiency as well as in technical and financial requirements. as such, air quality mitigation is ranging between bat and low-cost treatments. the mcp has planned to adopt several proposed mitigation measures to reduce dust emissions into the environment. the priority is clearly to mitigate pm dust emissions. the quarry processes emit considerable quantities of pm as a result of handling and grinding raw materials often to fine-grained size, which render dust emissions almost inevitable. the primary source of pm emissions includes fugitive and area source emissions that are generated from the handling, quarrying, and storage of raw materials. table 8.1 presents summary of mitigation measures that adopted at mcp. 11.2. mitigation of traffic impact primary measures adopted to mitigate traffic impacts include the proper dissemination of information regarding the transport schedule of limestone raw materials from the quarry site to the storage yards. in this respect, proper planning and development of a traffic plan that accounts for the reservations and inputs of nearby residents is essential to minimize potential inconvenience on commuters as well as to ensure the safety of motorists and pedestrians. as such, truck movements should be limited to off-peak hours to the extent feasible. in addition, adequate warning and signing are needed at least 500 m down and up-gradient from the entrance of the mcp to warn people that heavy equipment and trucks are frequent along these intersections. other traffic mitigation measures are presented in table 8.2. asian review of environmental and earth sciences, 2015, 2(2): 23-34 32 table-8.1. common control measures for particulate emissions from quarry processes of the raw materials 1: [17, 23-26]. table-8.2. traffic control measures in mpc. 11.3. mitigation of noise impact the outcome of the noise impact assessment reveals that noise levels in the areas surrounding mcp are higher than both daytime and nighttime according to the [27, 28] set for suburban residential areas. for this purpose, mitigation measures should be adopted in mcp to limit the impacts of noises on affected receptors. for this purpose, the erection of noise barriers to screen noise sources is proposed. usually, purpose-built noise barriers or screens constructed of appropriate material to be located along active work sites could result in noise reduction of up to 10 dba. it is anticipated that a movable noise barrier with a suitable footing and small cantilevered upper portion can be located within few meters of a static plant and about 5 m of mobile equipment. the provided insulation barriers can reduce noise impact up to 10 dba noise attenuation. in this case, noise levels may reach the daytime yemeni suburban noise standard (50 dba). additional mitigation measures include good site practice, selecting quieter mechanical equipment, as well as adopting proper schedule of construction activities. scheduling noisy activities during the daytime periods (7:00 am to 6:00 pm) will ensure that the noise standard set for the evening will not be exceeded at several instances. in addition, maintain proper onsite management to minimize noise emissions from the works during all times including: continuous maintenance for on-site machines, equipment intermittent in use are shut down between work periods, adopting low noise equipment, installing rubber coating in dumpers and entry chutes, using personal protection gear such as earplugs…etc, developing greenbelt around the quarry site, installing noise barriers around the quarry site, concerning mitigation measures that could be adopted to reduce ground vibrations generated particularly from blasting activities at the quarry site, mcp should adopt the following measures [22]: limit blasting to trained personnel, initiate periodic recording of blast vibrations, limit blasting activities to fixed days and hours that are acceptable with nearby receptors, disseminate the blasting schedule to nearby receptors, using mille-second delay detonator, deck charging, or other techniques to reduce vibrations and noise, increase the use of surface mining that do not require. 11.4. mitigation of soil, surface and groundwater impact the primary sources of potential impacts to water quality come from site runoff, which may directly enter soil, surface and groundwater waters. as such, open stockpiles of raw material should be covered with tarpaulin or similar fabric during rainstorm events to prevent the washing away, while earthworks at the quarry should be well compacted to prevent erosion especially during the wet season. furthermore, the installation of appropriate drainage system coupled with sedimentation tank is also imperative to re-duce exposure time to potential discharge sources. water from the settling tanks can be reused by mcp as process water or for irrigation and groundwater recharge purposes. efforts should also be made to clean the existing spillages in the wades where dried fuel spills should be collected and transported to a landfill while fresh fuel pools should be pumped in containers and re-used later on. other sources of potential water pollution include oil/fuel leaks and spills to the soil as well as the uncontrolled disposal liquid effluents. the improper handling of fuels at the fuel receiving area constitutes potential source of asian review of environmental and earth sciences, 2015, 2(2): 23-34 33 pollution at mcp. as such, fuel tanks should be bundled to limit the environmental damage, which is result from accidental spillage. bunds should be impermeable and resistant to the stored materials to avoid drains or taps that lead to blind collection point incorporate the distribution pipes within the bounded areas. in addition, oil and fuel residue that are generated from vehicle and machine service, vehicle wash bays and lubrication bays should also be mitigated to avoid potential soil, surface and ground water pollution. as such, oil-water separators and sand precipitators should be constructed, while oil collection trays should be provided to the operators at the vehicle and machine servicing areas [29]. spent motor oils should be collected in sealed containers and stored within closed drums located within the workshops until they are reused or recycled. oil contaminated cooling water should be treated in oil-water separators to remove oil. the treated water can be re-used to cool the flue gases in the conditioning tower as well as the cement mill [23, 29-31]. in case the suspended solids in the effluent are high in relation to the receiving waters, treatment may be required to reduce levels to maximum of 50 mg/l, which is the effluent requirement for direct discharge to surface waters [19, 23, 29-31]. 11.5. mitigation for terresterial biodiversity efforts should be made to preserve existing vegetation, avoid fires, prohibit hunting activities and the disposal of wastes of fuel and oil, hazardous in non-allocated areas, initiate a landscaping program on-site, as well as endorse well-planned restoration and reforestation plan for the quarry. the restoration and reforestation plans should be closely coordinated with al-hodiedah governorate and should use indigenous flora in re-vegetation schemes on-site since the use of exotic species hampers the re-colonization of the area by the local fauna. following closure to the quarry, several steps must be carried out to ensure the reintegration of the site with its surrounding including [15]: a) removal of wastes, b) reshaping of quarry walls to prevent unloading cracks and potentially dangerous collapse, c) reshaping of walls and loosening of compacted floors to facilitate re-vegetation and ensure the aesthetic quality of the restored landscape, e) retaining natural drainage on-site, f) re-vegetation using indigenous stocks of local vegetation such as the tamarix aphylla, salvadora persica, acacia spp, ziziphus spina-christi, commifora kataf and cadaba rotundifolia 12. conclusion environmental impact assessment and sedimentalogical study includes chemical analysis were carried out for the quarry site of al-maroua'ah cement factory in tehama plane, al-hodeida district nw yemen. the assessment of the quarry operations includes blasting of dynamite, shovels, trucks and primary crusher of the limestone raw materials was evaluated. the pollution includes dust emission, noise, gas emission from heavy duty viechels and fuel and oil waste were evaluates. mitigation plans was proposed to decrease the environmental impact for the minimum levels, which effected actually on the surrounding environments e.g. farms, populations, natural fauna and flora…etc. one of the most important point for mitigate pollution is the selection of quarry far from the villages and human populations to prevent the environmental impacts followed the specifications of who and yepa. the emitted dust and gases from the operations of the quarry machine makes impacts on the surrounding environments especially for the farms and the natural plants and animals, which are living in the region. for this, the site of quarry is selected in a mountain far from the vegetation, population and villages to avoid the expected environmental impact. mitigation plan for prevent or decreases the pollution impact to the minimum, was discussed. moreover, quality, chemical and mineralogical analysis for the limestone raw materials were also evaluated and expected pollutions impact was estimated. references [1] epa, "environmental guidelines for preparation of an environment management plan." environment and sustainable development directorate, act government. document. australian capital territory, canberra, 2013. [2] national, "national biodiversity strategy and action plan, sana’a, republic of yemen," ministry of water and environment/environmental protection authority (mowe/epa), report, 2004. [3] m. e. tucker, technique in sedimentology. oxford, london: blackwell scientific publication, 1988. [4] d. j. harrison, "industtrial mineral laboratory manual limestone," technical report wg/92/29 mineralogy ans petrology series. british geological survey, 1993. [5] l. walter and g. werner, "manual on the geological-technical assessment of mineral construction materials," geologisches jahrbuch, sonderhefte reihe h, heft sh 15bgr, bundesanstalt fur geowissenschaften und rohstoffe, geozentrum hannover, 2003. [6] z. r. beydoun, m. as-sururi, i. h. el-nakhal, i. al-ganad, r. baraba, a. s. nani, and m. al-awah, "international lexicon of stratigraphy, asia, fascicule 3(10b2), republic of yemen. sedimentary cover," z. geol. wiss., vol. 26, pp. 517-529, 1998. [7] e. flugel, microfacies analysis of limestones, book. berlin, heidelberg: springer-verlag, 1982. [8] p. a. scholl and d. s. ulmer-scholl, a color guide to the petrography of carbonate rocks: grains, textures, porosity, diagenesis. aapg memoir 77. tulsa, oklahoma, usa: published by american association of petroleum geologists, 2003. [9] geological assessment, "geological assessment of quarry limestone raw materials for cement industry in jabal falafel mountain, al-hodiedah goernerate. report," geological survey and mineral resources board (gsmrb), license and report, 2013. [10] a. j. alawi and n. v. mezhelovsky, republic of yemen: groundwater resources available for development. ministry of oil and mineral resources, geological survey and mineral resources board, sana’a,yemen. arya, s.p. air pollution meteorology and dispersion. new york: oxford university, press, inc. usa 1999, 1995. [11] yemeni, "yemeni standards for the discharge of industrial and commercial wastewater," (national water resources authority (nwra), sana’a, yemen, 1999. [12] a. w. a. iskander, "compiled. in collaboration with international & national technical consultant teams, republic of yemen ministry of agriculture and irrigation general directorate of farming irrigation in coordination with mop & ic. nt-mip," detailed technical studies on irrigation investment program for northern tehama modern irrigation project (nt-mip) final report-project, 2010. [13] mai, "ministry of agriculture and irrigation." agricultural statistics, book, 2007. [14] fao, "food and agriculture organization. appraisal of the groundwater resource in the amran region, sana’a governorate," technical report utf/yem/020/yem. sana’a, yemen, 1996. [15] guideline, "guideline on air quality models (revised)," epa-450/2-78-027r, u.s. environmental protection agency, research triangle park, nc 27711, united states, 1986. [16] usepa united states environmental protection agency, "air quality index: a guide to air quality and your health, office of air quality planning and standards." available http://www.airnow.gov/ [accessed 15 november 2004], 2002a. http://www.airnow.gov/ asian review of environmental and earth sciences, 2015, 2(2): 23-34 34 [17] usepa united states environmental protection agency, "population risks from indirect exposure pathways, and population effects from exposure to airborne particles from cement kiln dust waste," draft report. office of solid waste, united states, 1997. [18] usepa united states environmental protection agenc, protective noise levels: condensed version of epa levels document, 550/979-100. washington dc, usa: office of noise abatement and control, 1974. [19] pm10 sip development guideline, "epa-450/2-86-001, u.s," environmental protection agency usepa, research triangle park, nc 27711, united states, 1986. [20] usepa united states environmental protection agency, "key topics, air." available http://www.epa.gov/ebtpages/air.html [accessed 15 november 2004], 2002b. [21] epa, "guidelines for the preparation of noise management plans for development applications document." environment protection authority (epa), 2014. [22] wbcsd world business council for sustainable development, "towards a sustainable cement industry." available http://www.wbcsdcement.org, 2002. [23] iea international energy agency, tracking industrial energy efficiency and co2 emissions in support of the g8 plan of action (iea). france: head of communication and information office, 2007. [24] integrated, "integrated pollution prevention and control. guidance for the cement and lime sector," sector guidance note ippc s3.01. ea environment agency, bristol, uk, 2001. [25] inece international network for environmental compliance and enforcement, "training course for multimedia inspectors. industrial processes. cement industries." available http://www.inece.org/mmcourse/chapt6.pdf [accessed 1 december 2004], 1998. [26] i lo codes of practice, i lo codes of practice, protection of workers against noise and vibration in the working environment. switzerland: international labour office geneva, 1984. [27] m. c. barrientos, d. c. lendrum, and k. steenland, occupational noise, assessing the burden of disease from work-related hearing impairment at national and local levels, environmental burden of disease series, no. 9. series editors a. p.üstün, d. c. lendrum, c. corvalán, and a. woodward. geneva: world health organization (who), protection of the human environment, 2004. [28] s. z. k. al-mashaikie and a. k. al-karraz, "environmental impact assessment of al-maroua’ah cement plant factory in alhodiedah governate," yemen, report, 2013. [29] world bank, pollution prevention and abatement handbook part iii: cement manufacturing. washington, dc: world bank, united states, 1998. [30] awma, awma air and waste management association, air pollution engineering manual. new york: van nostrand reinhold, 1992. [31] npi national pollutant inventory, "emission estimation technique manual for cement manufacturing," version 2.1, department of the environment, water, heritage and art, australian governate, documaet, 2008. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://www.epa.gov/ebtpages/air.html http://www.wbcsdcement.org,/ http://www.inece.org/mmcourse/chapt6.pdf asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 1, 19-24, 2014 http://www.asianonlinejournals.com/index.php/arees 19 an investigation of the socio-economic implications of the violation of land use laws in kpakungu area of minna, niger state, nigeria maimuna, b.k. 1 --nsofor, g.n. 2 --suleiman, y.m. 3 1,2,3 department of geography, federal university of technology minna, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction a simple walk round the streets of minna with one’s eyes open afresh to the environmental conditions will tell that the majority of the people are living in squalid, dirty, unhealthy houses, streets and drainage lines [1]. many cities of the world in general and developing countries in particular were not planned initially while only few of them started as planned developments. they therefore, began to develop as villages or trade centers but they increased in sizes to what are big cities and urban centres today. such process of city growth has been marked with haphazard development, poor planning, urban sprawl and environmental degradation [2]. districts which often spill over into the surrounding residential areas and industrial sites originally located around the outskirts are engulfed by other developments as the cities grow. experience shows that, the variety of growth and changing of land use found in different cities complicate the process of identifying simple principles that govern the allocation of urban land uses [2]. land-use planning often leads to land-use regulations also known as zoning, but they are not one and the same. as a tool for implementing land use plans, zoning regulates the types of activities that can be accommodated on a given piece of land, the amount of space devoted to those activities and the ways that buildings may be placed and shaped [3]. law to protect mankind from environmental effects of his activities can be traced from the very ancient times; however, in those periods such regulations are mostly communal, and usually instinctively obeyed as being inherent and natural. the first recorded formal regulation or decree (law) in the field of environmental law was issued in 1273 by king edward i, when in order to protect the health of his subjects he issued a decree prohibiting the burning of sea coal [4]. environmental policy is any (course of) action deliberately taken (or not taken) to manage human activities with a view to prevent, reduce or mitigate harmful effects on nature and natural resources, and ensuring that man-made changes to the environment do not have harmful effects on humans [5]. environmental law can be seen as a body of laws which contains elements to control the human impact on the earth, but due to the non compliance with the law, the unpleasant social conditions created by pollutions, over crowding and diseases provided the stimulus needed for legal regulations. it was estimated that by the year 2008, over the years, there has been a rapid increase in population of people and socio-economic activities at kpakungu. the major reasons for this increase have been ascribed to the number of investments and socio-economic activities which have culminated in increased and deplorable living conditions. the residents, who are in desperate need of shelter to provide accommodation, tend to develop properties without taking account of the land use planning pattern or zoning regulation, thereby building properties that are not in conformity with the planning regulations. this study is aimed at investigation of the socio-economic implications of the violation of land use laws in kpakungu area of minna and the state and rate of compliance with these laws. questionnaire administration, personal interview and field analysis were utilised. the results indicate that the population growth and socio-economic activities in kpakungu have led to over stretching of facilities which encouraged over-crowding in the area and attendant consequences such as the growth of slums due to lack of plan and alteration to minna city master plan. therefore, state government should review the laws enacted ensuring that households abide by such laws and set a fine for non-compliance with the laws. there is also the need to establish a housing policy to provide sufficient and affordable housing for the lower income group so that illegal sub-divisions on buildings for residential purposes can be eliminated. keywords: compliance, land use, planning, environmental laws, violation, slum, regulation. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(1): 19-24 20 more than half of the world’s human population of 3.3 billion people will be living in the urban areas. it is also estimated that by 2030, this number would reach an all time high of 5 billion with many of these people poor [6].the socio-economic activities of man results in waste generation, but the rate of waste generated differs from community to community. the world health organization [7] refers to waste as “something which the owner no longer wants at a given time and space and which has no current or perceived market value” indiscriminate disposal and dumping of refuse or waste has become a practice in nigerian cities. most of the waste dumps are located along residential houses, markets, drainages and on roads. the development of land use systems which meet the needs of present and future generations without causing environmental degradation remain one of the major challenges we are confronted with today. for sustainable development, such land use systems must have the capacity to prevent and control any form of gross abuse or unsustainable use of land resources [8]. urbanization is therefore, an inevitable, but positive concomitant of economic change. the growth of slums, the concentration of poverty, as well as the illegal land use and their attendant social disruptions in cities pose a great challenge. it is also true that no state can achieve a significant economic growth without urbanization [9]. the essence of compliance with set standards, laws and regulations in property development is to ensure the health, welfare, comfort and general well being of the people residing around the areas after construction [9]. 2. study area kpakungu is a residential settlement within an area of minna the capital of niger state, which is the focus area of the research. it is situated along minna-bida road. the indigenous residents are the gwari speaking people. minna being the state capital with administrative set up has attracted a considerable number of ethnic groups with different social and cultural background. from 2006 population census, kpakungu is about 201,429 out of the entire population of minna. males consist of 105,803 and females 95,626 given the total of 201,429. kpakungu, the study area is a settlement located in chanchaga local government, niger state and lies between latitudes 8o 20’n and 11o 30’n and longitude 3o30e and 7o 29’e. one of the 36 states of nigeria was created out of the defunct north western state on 3rd february, 1976, situated in the north central geopolitical zone. the state comprises 25 local government areas grouped into 3 administrative zones a, b, c, with each zone having 8, 9 and 8 local government areas respectively. the state is bordered to the north by zamfara state, to the north west by kebbi state, to the south by kogi state, to the south west by kwara state while kaduna state and the federal capital territory border the state to the north east and south east respectively (figure 1). figure-1.the study area (kpakungu, minna, niger state, nigeria) 3. materials and methods a. the methodology used for this research employed the use of descriptive analysis. it involved the use of tables, charts and simple percentages. b. data on the level of awareness and rate of compliance were collected through field survey and interviews. c. data on laws to guide land use were collected through the interpretation of niger state gazette asian review of environmental and earth sciences, 2014, 1(1): 19-24 21 d. land use types and location of land use were interpreted using the minna master plan. e. the socio-economic indicators that have great impact in the violation of land use laws. 4. results and discussion table-1.are there environmental laws existing to guide land use in kpakungu laws guiding land use frequency percentage (%) yes no total 114 132 246 46.3 53.7 100 table 1 depict that, 53.7% of the residents are not aware of the environmental laws existing to guide land use in kpakungu while 46.3% of the residents believed that there are environmental laws existing to guide land use in kpakungu but it is not being enforced by the agency involved in land use planning and development. figure-2.buildings constructed at kpakungu figure-3.houses built on drainage network figures 2 and 3 illustrates that buildings were constructed without regards to the environmental effects, drainages were blocked with waste materials and the environment is polluted as litters are seen at every corner of kpakungu. it showed that environmental laws are not properly understood about the negative effect it has on the residents and the entire kpakungu community at large. table-2.environmental laws existing in kpakungu by nisepa and nudb laws existing in kpakungu frequency percentage (%) no yes total 3 7 10 30 70 100 table 2 shows that there are particular laws existing for kpakungu area by the agency involved. about 70% believed that while 30% believe that there are no laws guiding land use in kpakungu.kpakungu is a residential settlement sited on the western side of the town and it gains an immediate access from bida road on its southern side and consists of various land use types located at the same area. asian review of environmental and earth sciences, 2014, 1(1): 19-24 22 figure-4.land use types present at kpakungu area figure 4 depicts that 51.6% of land use in kpakungu is for residential purposes, 41.5% of land use is for commercial purposes, about 1.2% is used for industrial purposes, 1.6% is used for recreation purposes, while 4.1% of the residents believed that there are other uses not necessarily the ones mentioned. therefore, this signifies that majority of the kpakungu residents use land for residential purposes. figure-5. awareness of environmental laws figure 5 depict that about 60% of the residents are not aware of environmental laws, while 40% of the residents are aware of the environmental laws but are not abiding by the laws because they believe it is not binding on them. it is believed that government must enforce a law before it can be adequately adhered to. 13 20 57 9 most successful successful moderately unsuccessful figure-6.performances rating of awareness campaign for kpakungu residents figure 6 present the rating assessment of the efficiency of nudb and nisepa as rated by the kpakungu residents. from the analysis, 13% of the residents ranked nudb and nisepa as most successful, 19.9% of the residents think that the performance of both nudb and nisepa is successful, 57.3% rated nudb and nisepa as moderately successful and finally 9.8% rated nudb and nisepa as unsuccessful. from this analysis, it shows that the performance of niger state urban development board and niger state environmental agency is relatively average and appreciated by the kpakungu residents but calls for improvement to make their impact felt in the study area and the society at large. 40 60 environmental awareness yes no asian review of environmental and earth sciences, 2014, 1(1): 19-24 23 table-3. level of compliance with environmental laws level of compliance frequency percentage of the total excellent good poor very poor total 22 46 121 57 246 8.9 18.7 49.2 23.3 100 table 3 depicts that about 49.2% of the kpakungu residents rated the level of compliance as poor, 23.2% rated the level as very poor. this may be because majority of the residents are not aware of environmental laws, or of agencies concerned with land use planning and environmental protection. this indicates that the level of compliance is generally poor in kpakungu. table-4. socio-economic implications of the violation of land use laws in kpakungu socio-economic implications frequency percentage (%) yes no total 162 84 246 66 34 100 table 4 indicate that about 66% of kpakungu residents believe that there are socio-economic implications associated with illegal land use and non-compliance with environmental laws while about 34% of the residents are of the view that there are no implications associated with illegal land use. this result strongly indicates that there are socio-economic implications associated with illegal land use and non-compliance with environmental laws at kpakungu, whether the implications are felt or not. there are laws guiding development as enshrined by niger state gazette, but the laws are not enforced to guide land use in kpakungu area and the state at large. the result showed that there are different land use types which include: residential, commercial, industrial and recreational land use at kpakungu and it signifies that majority of the kpakungu residents’ uses land for residential purposes. the physical layout at kpakungu hinders the provision of deports for effective collection of solid waste. therefore, the environment serves as toilet to most residents in the area, especially for children. these contributed to poor management of canals and channels. about 60.2% of the residents are not aware of any environmental law existing to guide land use in kpakungu. about 60% of the staff interviewed are not satisfied with the level of compliance with the land use act and environmental management at kpakungu but believed that when properly enforced kpakungu will be a socially and economically attractive place to be. also, the kpakungu residents rated the level of compliance as poor, this is because majority of the residents are not aware of environmental laws. the various socio-economic activities and establishments along minnabida road attracted population to kpakungu and this resulted in increased housing demand thereby increasing the growth of slums in kpakungu, also, the environmental conditions of some properties around the neighborhood are prone to disaster and thereby can lead to scaring away of investors. 5. conclusion and recommendations in view of the present circumstances and situation in kpakungu, environmental condition with respect to laws governing land use planning and management pose a great challenge, thereby encouraging the growth of slums and poor management of city canals/channels. actually, there are laws and also enforcement organs but violation of the laws still persist due to lack of measures set aside for offenders. it is therefore recommended that niger state government should review and enforce the environmental laws existing to guide development in kpakungu and the state at large by establishing a housing policy to provide sufficient and affordable housing for the lower income group so that illegal sub-divisions on buildings for residential purposes can be eliminated thereby sustaining land use pattern, that the regulatory authorities should be proactive in ensuring environmental protection and land use management for effective land use control and management and landed property owners or occupiers should ensure that they obtain building approvals before constructing or change in use of their property to ensure effective land use control. references [1] max lock group, minna master plan: final report, max lock group nigeria limited planning and development consultants kaduna. kaduna: new nigerian newspapers limited kad, 1980. [2] o. a. oyebanji, "principles of land use economics, mushin, lagos sam otu nigeria co," 2003. [3] wikipedia, "land use planning from wikipedia: the free encyclopaedia." available http://en.wikipedia.org/wiki/land-use_planning, 2013. [4] m. el-surur, "a lecture note on environmental law for post graduate students: department of geography, federal university of technology minna," unpublished material, 2012. [5] wikipedia, "environmental policy instruments: wikipedia the free encyclopaedia." available http://en.wikipedia.org/wiki/environmental_policy, 2013. [6] dap, "development action plan of niger state 2007-2011. niger state," 2007. [7] word health organization, "treatment and disposal of waste. being a report of world health organisation scientific group," geneva, 1966. [8] t. l. muhammad, "environmental law and land use in nigeria," presented at the a paper for the second colloquium on environmental law and land use organized by iucn academy for environmental law bonn, germany in collaboration with university of nairobi, kenya. between 29th september and 2nd october, 2004, at merica hotel, nakuru, kenya, 2004. [9] i. garba, "socio-economic implications of unplanned property development in kpakungu, minna. unpublished project dissertation," department of estate management, federal university of technology minna, 2009. http://en.wikipedia.org/wiki/land-use_planning, http://en.wikipedia.org/wiki/environmental_policy asian review of environmental and earth sciences, 2014, 1(1): 19-24 24 bibliography [1] wikipedia, "urban planning: from wikipedia, the free encyclopaedia.” available http://en.wikipedia.org/wiki/urban_planning, 2013. [2] wikipedia, "land-use and planning: wikipedia the free encyclopaedia. retrieved from categories," land. available http://en.wikipedia.org/w/index.php?title=land-useplanning&oldid=509065258, 2013. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://en.wikipedia.org/wiki/urban_planning, http://en.wikipedia.org/w/index.php?title=land-useplanning&oldid=509065258 asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 1, 1-4, 2014 http://www.asianonlinejournals.com/index.php/arees 1 multi hazard risk assessment using gis techniques in the mbo area of nigeria okpo o. ekere 1 --joseph c. udoh 2 1,2department of geography and regional planning faculty of social sciences, university of uyo, uyo, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction natural hazards including erosion and flooding are part and parcel of the environment in which we live. they do not discriminate between people or countries. however, no disaster is entirely natural. for an example, although erosion is a natural process, it has increased dramatically by human land use, especially industrial agriculture, deforestation and urban sprawl. land that is used for agricultural generally experience a significant greater rate of erosion than that of land under natural vegetation, or land used for sustainable agricultural practices [1]. equally, floods are caused by a variety of factors, both natural and manmade. apart from the obvious causes of floods like heavy rainfall, melting snow and ice, and frequent storms within a short period of time duration; the common practice of humans to build homes and towns near rivers and other bodies of water have contributed to the disastrous consequences of floods. generally, increased urbanization, the settlement and industrialization of highly exposed regions, the vulnerability of modern technologies and anthropogenic changes in the environment, have led to increased levels of disasters globally [2]. risk is the expected lose as a result of potentially damaging phenomena within a given time period and within a given area [3]. it can be analyzed by assessing three major components – the probability of an event with a certain magnitude (hazard); the vulnerability of the elements at risk that are exposed to the event to the event with a certain magnitude (vulnerability); and, the costs relating to these elements at risk (risk). risk assessment forms an important input in disaster management, in the design of development plans and in emergency response planning. it combines information on the nature hazard with information on vulnerability of the targets. it is helping to clarify decision making and the development of mitigation strategies [2]. vulnerability is an important concept in hazard research and is central to hazard mitigation strategies. within the framework of the united nation’s international decade of natural disaster reduction (idnur), for an example, vulnerability assessments are used to determine the potential damage and loss of life from extreme natural events. they are important as well in proposing hazard reduction alternatives where mitigation normally takes the form of structural (engineered) approaches to hazard reduction [4]. most of the data required for disaster management have spatial components and also change over time. hence, remote sensing and geographic information system (gis) are very useful for analyzing various components of risk. while remote sensing help collect environmental data, the gis helps store, integrate and display the data. various gis based studies exist on hazard, vulnerability and risk assessment. examples include, multi-hazard risk assessment in urban areas [5]; landslide hazard zonation and analysis [6] and, vulnerability to environmental hazard [7]. the study area mbo and environs of south eastern nigeria are experiencing frequent inundation by flood and erosion hence this research is aimed at generating vulnerability hazard and risk maps as decision support tools for policy makers. rainfall, elevation, slope, soil association and hydrology were used as input layers to model the hazard layers while population density, vegetation and normalized difference vegetation index (ndvi) were used to model the vulnerability layers. risk maps were generated weighting and combining the hazard and vulnerability layers using the single output map algebra function of arcmap soft ware. the final multi hazard risk map , derived by combining the flood and erosion risk maps shoed that 119.62km 2 (15.12%), 193.94km 2 (24.52%), 292.33km 2 (36.95%) and 185.20km 2 (23.41%). the study, using gis, has revealed an objective way of understanding and dealing with the impact of hazards in the study area. keywords: hazard, vulnerability, risk assessment, gis, akwaibom state. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(1):1-4 2 2. aim and objectives the aim of this work was to carry out a multi hazard risk assessment using gis techniques in mbo and environs in akwa ibom state of nigeria. specific objectives of the study include: to quantify and model hazard and risk; make an inventory of these hazards; map the elements at risk; and, produce a multi – risk map that would inform the decisions and developments of effective response measures, for the study area 3. the study area the study area (fig.1) is the south eastern akwa ibom state comprising four local government areas (lgas) – mbo, udunguko, oron and urue offong oruko. it lies within latitude 4 0 30 i 5 0 0 i north and longitudes 8 0 0 i 8 0 20 i east. with a total landmass of 791.1m 2 , it is bounded on the north by okobo lga and on the south by ibeno lga, to the south by cross river and to the west esit eket and eket lgas as shown in figure 1. it has a population density 399.33 people per square kilometers with the people being predominantly fishermen and farmers. the landscape of the study area comprises of generally low lying plain and riverine areas with no portion exceeding 175meters above sea level. the area is traversed and criss-crossed by a large number of creeks, rivers, streams and canals. the likelihood of erosion and flooding is high in the study area because of the intricately woven network of creeks, rivers and inlets. rich in crude oil and gas, the area is noted for its wetlands, sandy coastal ridge barriers, brackish or saline mangroves, fresh water swamp forests as well as lowland rainforests. 4. methodology analogue maps on vegetation and land use, soil association, hydrology, rainfall, relief and drainage, and population density were scanned into a computer, opened on a gis environment and digitized to create a digital map layers that were used for the analysis. equally, landsat tm of 2003 with 30m x 30m resolution were used to extract the vegetation and normalized difference vegetation index (ndvi) used too for the analysis. the digital elevation model of the study area was used to extract slope, elevation and aspects also used as input in the analysis. hazard and vulnerability analysis are needed to model risk. 4.1. vulnerability modeling for risk assessment to be valid, certain elements must be critical to that assessment. in carrying out multi – hazard risk assessment of the study area, what are likely to be affected by the hazard is of prominence to the study. population; vegetation and land use, and ndvi were identified and used as the vulnerability elements at risk to the hazards. the vulnerability layer was modeled by weighting and combining the elements using the single output map algebra function of arcmap soft ware thus: vulnerability layer = (population density x 0.4) + (vegetation & land use x 0.2) x (ndvi x 0.4). the vulnerability map displayed in fig. 2 was the resultant output. 4.2. multi hazard modeling hazards for this study were limited to flood and erosion. in the absence of data for these hazards, the following were used as proxies to model them: slope, rainfall, hydrology soil association and elevation. the elements were weighted and used to model the hazard as follow: erosion hazard = (rainfall x 0.3) + ( slope x 0.25 ) + (soil association x 0.20) + (hydrology x 0.25) flood hazard = (rainfall x 0.3) + ( elevation x 0.25 ) + (soil association x 0.20) + (hydrology x 0.25) 4.3. risk layer the final risk layer of the study area (fig. 5) was gotten by deriving, combining and classifying the erosion and flood risk layers of the study area using the single output map algebra function of arcmap soft ware as follows: erosion risk layer = (erosion hazard x.05) + (vulnerable layer + 0.5) flood risk layer = (flood hazard x.05) + (vulnerable layer + 0.5) the resultant output were erosion (fig. 3) and flood risk (fig. 4) maps respective. these were combined to form the multi – risk map as follows: multi – hazard risk map = (multi hazard layer x.05) + (vulnerable layer + 0.5). asian review of environmental and earth sciences, 2014, 1(1):1-4 3 the vulnerability, hazard and risk maps were all classified into low, moderate, high and very high zones. the multi risk classification of the zones is displayed on table 1 to show the areal extent of each zone in the study area. table-1.tale showing the multi risk classes risk class area (km2) % low 119.62 15.12 moderate 193.94 24.52 high 292.33 36.95 very high 185.20 23.41 total 791.09 100 source: analysis by researchers. 5. discussion this study generated a multi-hazard risk map of mbo and environments in a gis environment using a data base created with vegetation and land use, soil association, hydrology, rainfall, relief and drainage, and population density data of the study area. generally, gis based risk is assessed by combining vulnerability and hazard layers as no risk is encountered if there hazard events but no vulnerable population or if there is a vulnerable people but no hazard event. hence risk is a function of a varying degrees of hazard and varying degree of vulnerability [8]. the study has revealed risk zones in the study area that would help policy makers identify specific risk zones for intervention measures. for an example, the high and very high risk zones being 60.36 % it means that there is need for mitigation measures in order to preserve the study area from the harmful effects of erosion and flood. the study area being in a low – lying coastal needs such measures as the erosion and flood maps have shown that these hazards are found in all the 4 lga’s located here. the study has also shown that the areas of moderate (24.52%) and low (15.12%) risk have to be preserved and well maintained so that erosion and flood does not spread.a combination of remote sensing and gis techniques was used in the risk assessment. remote sensing lansat imagery and dem data has been used in providing timely information on the state of the environment hence making the monitoring and detection of environmental hazards easier than conventional text based methods. the remote sensing and other spatial data of the study area were stored and integrated in a gis data base for subsequent analysis and presentation. 6. conclusion the study has revealed the use of gis for multi – hazard risk assessment for effective management of the study area. risk, hazard and vulnerability maps were generated that could serve as useful decision support system for planners and policy makers. with these, areas for mitigation measures could easily be identified and tackled easily. asian review of environmental and earth sciences, 2014, 1(1):1-4 4 7. dedication this paper is dedicated to the memory okpo o. ekere, the co-author who died before the publication of this work. references [1] w. c. bogard, "bringing social theory to hazards research. conditions and consequences of the mitigation of environmental hazards," sociological perspectives, vol. 31, pp. 147 -168, 1989. [2] j. ingleton, natural disaster management, international decade for natural disaster reduction (idndr) 1991 – 2000. leicester: tudor rose holdings limited, 1999. [3] r. socolow, c. andrews, f. berlkhout, and v. thomas, industrial ecology and global change. cambridge: cambridge university press, 1994. [4] a. coburn and r. spence, earthquake protection. new york: wiley, chichester, 1992. [5] c. westen, l. montoya, l. boerhoom, and e. coto, multi – hazard risk assessment using gis in urban area: a case study for the city of turi alba, costa rica. the proceedings of regional workshop on best practices in disaster mitigation lessons learned from the asian urban disaster mitigation program and other initiatives, 24-26 september, 2000, bali, indonesia. [6] k. chau, y. sse, m. fung, w. wong, e. fong, and l. chan, landslide hazard analysis for hong kong using landslide inventory and gis. computer and geosciences, vol. 30, pp. 429 – 443, 2002. [7] t. yarnal, "socioeconomic restructuring and vulnerability to environmental hazards in bulgaria," disaster, vol. 18, pp. 95 – 106, 1994. [8] p. blaikie, t. cannon, i. davis, and b. wisner, at risk: natural hazards, people’s vulnerability and disasters. london: routledge, 1994. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences vol. 4, no. 1, 20-27, 2017 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2017.41.20.27 20 discontinuous nature of phreatic aquifers in granitic rocks at watershed scale: a stratiform model from perennial streams and well data théodore koffi yao1  olivier fouché2 konan emmanuel kouadio3 marie-solange oga4 (corresponding author) 1,3,4department of science and technology of water and environmental engineering, faculty of earth sciences and mineral resources, university felix houphouet-boigny, abidjan, 22 bp 582, côte d’ivoire. 2conservatoire national des arts et métiers de paris, dept. icener – service de géotechnique, 2 rue conté, 75003 paris, france. abstract the study was carried out within 4,000 km2 segment of sassandra watershed located in soubré, south-west of côte d’ivoire where coffee and cocoa production are preponderant. this work aimed to provide a general methodology in order to draw the flow directions and map the potential productive aquifer in hard-rocks. drilling data, remote sensing, and geomorphic data in a context of weathered plutonic and metamorphic precambrian were used. the regional water table was modeled through a linear relationship between the topographic surface of the digital elevation model and the base surface of the perennial streams thalwegs. as result, a map of regolith thickness obtained has been compared with the geology to emphasize their relationship. furthermore, other correlations have been found between the hydraulic data and geomorphological features to get more precise stratification model. concealed by the regolith, the hard-rock aquifer is made up of three layers. from top to bottom we have the saprolite (< 10 m), the weathering induced fissured layer (35 m mean thickness) below the base of the saprolite and finally, the unweathered with very low hydraulic conductivity. each layer is characterized by a constant density of water-bearing fissures. this shows the impact of a stratiform weathering profile on the layering of the aquifer. high variability of observing yields is mainly due to thickness heterogeneity of the higher-storage regolith and underlying higher-conductive fissured saprock. also, the wells tapping water under a regolith with medium or high thickness were the most productive justifying that regolith thickness mapping is a first rank tool in hydrogeology prospecting. the thickness map obtained from the interpolated base surface of the regolith and the dem represents a useful tool for groundwater management. keywords: precambrian, dem, regolith, saprock, fracture. citation | théodore koffi yao; olivier fouché; konan emmanuel kouadio; marie-solange oga (2017). discontinuous nature of phreatic aquifers in granitic rocks at watershed scale: a stratiform model from perennial streams and well data. asian review of environmental and earth sciences, 4(1): 20-27. history: received: 6 october 2017 revised: 27 october 2017 accepted: 2 november 2017 published: 7 november 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 21 2. general information of the study area ....................................................................................................................................... 21 3. method and data ............................................................................................................................................................................. 22 4. results and interpretations ........................................................................................................................................................... 23 5. discussion .......................................................................................................................................................................................... 26 6. conclusions ....................................................................................................................................................................................... 26 references .............................................................................................................................................................................................. 26 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=théodore koffi yao https://orcid.org/orcid-search/quick-search?searchquery=olivier fouché https://orcid.org/orcid-search/quick-search?searchquery=konan emmanuel kouadio https://orcid.org/orcid-search/quick-search?searchquery=marie-solange oga https://orcid.org/orcid-search/quick-search?searchquery=théodore koffi yao https://orcid.org/orcid-search/quick-search?searchquery=olivier fouché https://orcid.org/orcid-search/quick-search?searchquery=konan emmanuel kouadio https://orcid.org/orcid-search/quick-search?searchquery=marie-solange oga https://orcid.org/orcid-search/quick-search?searchquery=théodore koffi yao https://orcid.org/orcid-search/quick-search?searchquery=olivier fouché https://orcid.org/orcid-search/quick-search?searchquery=konan emmanuel kouadio https://orcid.org/orcid-search/quick-search?searchquery=marie-solange oga https://orcid.org/orcid-search/quick-search?searchquery=théodore koffi yao https://orcid.org/orcid-search/quick-search?searchquery=olivier fouché https://orcid.org/orcid-search/quick-search?searchquery=konan emmanuel kouadio https://orcid.org/orcid-search/quick-search?searchquery=marie-solange oga https://orcid.org/orcid-search/quick-search?searchquery=théodore koffi yao https://orcid.org/orcid-search/quick-search?searchquery=olivier fouché https://orcid.org/orcid-search/quick-search?searchquery=konan emmanuel kouadio https://orcid.org/orcid-search/quick-search?searchquery=marie-solange oga asian review of environmental and earth sciences, 2017, 4(1): 20-27 21 1. introduction côte d’ivoire, surface and subsurface geology of are made up of 97% of crystalline and metamorphic bedrock [1]. here and all over the world, bedrock aquifers are considered among the least understood groundwater resources. although these aquifers have a regional extension, they actually respond in a discontinuous model that often shows a wide range of yields in the well. this is generally attributed to the abundance of all scales fractures, which more often playing the role of water conduit. however, different types of fractures (primitive joints, tectonics-inherited faults, and secondary weathering-fissures) have not similar hydrogeological functions. moreover, all conclusions have to be drawn from the heterogeneity conception to the vertical weathering profile. observed hydraulic gradients are not able to explain the variability of yields and heterogeneous permeability due to fracture networks and/or weathering profiles [2]; [3]. the induced significant borehole failure rate, around 50% in the granitoids of côte d’ivoire, with little or no improvement since the first statistics published by lenck [4] testifies to the difficulty of predictive exploration for groundwater in this environment. this comes from the limited sensitivity of current exploration techniques and above all, poor understanding of the controls on hard-rock aquifer occurrence and flow direction. while the most immediate need is to improve borehole’s success rate, to assist present actions and planning a crucial issue for longer-term sustained development in the context of human migrations and climatic changes. in addition, we need to evaluate overall resource and aquifer occurrence within a regional watershed, not only specialization of the groundwater occurrence, but also the direction of groundwater’s flow is problematic. the last one is often presumably controlled by topography and geological structure but the relative influence of these factors in crystalline rocks still raises basic interrogations [5]. aquifers contained into the fresh bedrock are of rare occurrence due to negligible intergranular porosity and low tectonic fracture network storativity. higher porosity and permeability of hard-rock may locally arise within major brittle structures [6]; [7]; [8]; [9]. tunnel engineering in saturated rock masses also provides opportunities to develop understanding on the subsurface hydraulic behavior of recent studies in relation to mining or radioactive waste disposal, especially from borehole data in low permeability bedrock at depth, have also increased knowledge of the detailed hydraulics of fracture systems fractured media [10]; [11] at local scale. however, although it was proposed by de dreuzy, et al. [12]; kouame, et al. [13] and other advocates of the percolation theory, a regional approach cannot be mainly a geometrical extrapolation of the local hydraulic mechanisms of fresh bedrock by computing a regional permeability of a lineament network. rather, it is necessary to focus on the granitic rocks and combine at greater scale lithology, morphology, hydrology, structural geology, weathering profile and well data [14]. indeed, in those rocks, in the absence of any sedimentary cover, groundwater flows through discontinuous aquifers characterized by a vertical weathering gradient with variable porosity from the surface below to almost unfractured rock at depth [15]. at the top, weathered disaggregated rocks are both sandy and clay-rich and so have very low intergranular permeability. clay strata, especially in the saprolite which is the bottom layer of the regolith, may in places support some isolated perched aquifers [16]. between the regolith aquifer and the deeper unfractured bedrock, both with low permeability, it is usual to distinguish the fissure aquifer with low porosity but much higher permeability, almost entirely dependent on secondary fissures due to weathering. the work conducted here in a part of sassandra watershed located in soubré is intended to provide a general methodology for the investigation of flow directions and mapping of favorable areas for the occurrence of a productive aquifer in hard rocks and to contribute to the comprehension of groundwater flow in hard rock. the borehole dataset including regolith thickness, initial hydraulic head and well yield, is examined in relation to the topographic surface and the perennial streams. we focus on a 4,000 km2 area within the granitoids. the model took from wyns, et al. [17]; yao, et al. [18] allows for mapping the water table and the regolith-saprock interface. then a map of regolith thickness achieved is compared to the geology of this area. 2. general information of the study area the study region comprises a segment of the sassandra river’s watershed located in west africa especially in the southwest of côte d’ivoire between latitudes 5°19 6°34 and longitudes 6°12 7°08, and has a surface area of 8 590 km2 (fig. 1). figure-1. location and geology of the study area source: yao [19]. asian review of environmental and earth sciences, 2017, 4(1): 20-27 22 the geomorphic setting is a vast and slightly waved plateau formed by precambrian crystalline rocks, with 200 m average elevation and inclined 0.1% southwards, incised by a dense pattern of tributaries. the region is drained by sassandra river which offers a variety of configurations along its course and benefits from a subequatorial climate (hot and humid). the study region comprises a 100 km segment of the sassandra river’s watershed. a 210 m elevation seems to be characteristic scale of the water table along the limit of the watershed. excluding the isolated peaks at an elevation exceeding 300 m around the more recent granitoids (fig. 2), the typical elevation gradient in the direction transverse to the sassandra river implies a hydraulic gradient of about 0.2%. it is the case of the lobo valley, a major tributary of sassandra river: its stream south-westwards is controlled by the hlfz (hana-fault zone) which plays the role of a hydraulic barrier as outlined by the great meander of sassandra river where abutting on the fault. the barrier effect due to fault gouge has been reported elsewhere for such fault zones through precambrian rocks in other geological contexts [20]; [21]. figure-2. digital map of the relief from the dtm of studied area source: primary data analysis (2017) actually, rains are abundant (between 1600 mm and 1800 mm) and reach a peak around june and july. during the year, temperatures vary between 26 °c and 32 °c. the great n-s sassandra fault belongs to a family of impressive structures which may have originated [22] as ductile shears or sutures during the early stage of the eburnean orogeny with repeated subsequent movement to include late brittle faulting in the intrusives. these faults zones guide the course of the main continental streams as for instance the sassandra river north of the main sw-ne trending crustal structure typical of the baoule-mossi domain [23] that we will refer to hlfz, the northern part of the study area belongs to the main supracrustal sequences of birimian [24]. at the south of the hlfz, outcropping rocks associate varied intrusive granitoïd lithologies of the eburnean orogeny with reworked metamorphosed archean components (cf. fig. 1). the relatively sodic early rocks underlie featureless plateau whereas the latter potassic plutons form positive outcrop features, locally with a thick saprock. the high potassium content and abundance of quartz prevented the saprock to be broken down into a thick soil cover and now allows it to be a good aquifer. retrogressive metamorphism replaced biotite by other hydrous mineral phases (chlorite, amphibole) which made the host rock less susceptible to weathering [25]. 3. method and data in order to tackle both questions, groundwater occurrence and flow direction, we referred to the conceptual scheme of a stratiform bedrock inherited from a single phase weathering paleoprofile, proposed by wyns, et al. [17] and further developed in dewandel, et al. [26] and yao, et al. [18]. the layering roughly follows the paleotopography and presents a gently dipping sequence at regional scale. the model stands for two superposed aquifers, the regolith and the saprock or “fissure aquifer” with possible exchange between them and with some vertical tectonic fault zones allowing for a deeper flow component. the used model was demonstrated in yao, et al. [18] which was being forwarded. in this model, other fracture zones being isolated from both the surface and fissure aquifer are therefore non-conductive. the base surface of the perennial streams’ thalwegs, denoted sr (r for reference), is obtained by kriging of the values extracted from the dem along the perennial streams. the real potentiometric surface sp, including borehole data, is still unknown at this stage. following chilton and foster [16] let us define the parameters a and b at every point by: a = st – sr and b = sp – sr. (1) asian review of environmental and earth sciences, 2017, 4(1): 20-27 23 next to a perennial stream, the surfaces sp and st are likely to intermingle. when increasing the distance, however, we can hold the following tendency for true: the higher a point between two streams (nearer to interfluves), the deeper the hydrostatic level. now, considering the three surfaces sr, sp, and st, we could better write b = p x a – h with p, h, real numbers. finding such a relation will allow determining the hydraulic head as a direct function of the soil elevation. the 1-degree digital elevation model (dem) is obtained from the shuttle radar topographic mission (srtm), with 3 x 3-arc-second data spacing (90 m). the drainage network and topography were extracted from the dem and three paper elevation maps, 1:200,000 scaled, elaborated in 2001. the borehole dataset provides the depth of a mechanical interface which is the contact between saprolite, i.e. the disaggregated but structure-preserved lower horizon of the regolith, and underlying saprock which is still cohesive but weathered fissured bedrock. below this interface, with increasing depth, the saprock to fresh bedrock junction is transitional or even fluctuating in banded sequences. thus, the depth of the mechanical interface is also the thickness of the regolith and we denote it by na (a for alteration). the depth of the hydrostatic level measured at the borehole completion is denoted np (p for potentiometric), and also the terrain elevation zt is transformed to zp into an altimetric level. even when the elevation of the site was recorded in the borehole file, it did not turn out to be more precise that by pointing the x, y position on the dem. proceeding this way to acquire zt, systematically, one deals with an absolute error of 10 m along the vertical axis. then, the main source of uncertainty resides in x, y positions of the boreholes: locations are estimated to be accurate to ± 100m. gathering boreholes drilled at years of distance, the hydrostatic level database obviously is diachronous. here we advocate that the effect of the year or month of borehole completion is negligible for our purpose: the diachronous database will be considered as a homogeneous source of data. we compile water-well yields reported from drillers’ logs. the yields are modest, typically less than 5m3/h, and many boreholes had run dry or been abandoned on completion. in this study, we only analyze data from wells that were considered as successful and are still productive to date. detailed water level and yield evolution are not available, only being registered the first air lift test when the borehole has been completed. yields were generally determined as the rate of water that can be air-lifted on a continuous, short-term (tens of minutes) basis. such method introduces an unquantifiable variance in measured yields but is acceptable for a statewide or regional evaluation. 4. results and interpretations 4.1. flow directions: a model of the water table it turned out to be sufficient to extract 220 values of zt, each one representative of a 90 m x 90 m cell, since the 220 points are scattered enough to make an interpolation (fig. 3) and get a map of sr. the extracted value is a superior bound of the water level in the stream. however, as soon as we will observe boreholes at a distance of a few hundreds of meters from a perennial stream, the value of zt extracted at the river is a good local minimum for sr and sp. figure-3. elevation of the basal surface of the thalwegs of perennial streams (surfer7®), kriged from 220 values pointed along low elevation channels of the dem source: yao, et al. [18] working on a population of 55 boreholes (fig. 4), three correlations were found but a good correlation factor found for b is: b = 0.92 a – 7.00 m (r2 = 0.95) (2) we continued to improve the correlation achieved; so, with another dataset, wells taken away from the streams, we found this time: b = 1.00 a – 9.64 m (r2 = 0.97). (3) asian review of environmental and earth sciences, 2017, 4(1): 20-27 24 figure-4. relation between the land surface, the base surface of the thalwegs of perennial streams, and the hydrostatic level in 55 boreholes source: yao, et al. [18] the slope very close to unity of this relation means that sp lies about 9.6 m in average under st in a quasiparallel fashion. working on the b/a relation, wyns, et al. [17] have interpreted the negative value of y-axis at the origin as the depth between the water surface and the banks. however, the water surface of the rivers in the study area is incised 1 m or 2 m below the banks. our result is rather consistent with the mean np value (7.33 m) and with the fact that most of the studied boreholes are sited away from perennial streams for safety towards flooding hazard. thus, we are induced to distinguish two relations: one in the neighborhood of the thalwegs and another at longer distance. in the vicinity of the perennial streams, we suggest making possible the convergence of the surfaces sp and sr, i.e. with an assumption the negligible incision below the banks. to satisfy this condition, we need to force the relationship to respect linearity in a strict sense: then, we find b = 0.74 a without losing too much signification level (r2 = 0.90), valid in the range of values up to 60 m. let notice that the value 0.74 is very close to the value found by wyns, et al. [17] through the “with bank incision” assumption. from these linear relations, we deduce the elevation of sp in any 90 m x 90 m cell with the help of a simple transformation of the base surface sr. the relation zp – zr = 0.74 (zt – zr) gives: zp = 0.74 zt + 0.26 zr. beyond the value a = 60 m, the best linear fitting with a slope close to 1 should be used since sp, despite its variability, is roughly parallel to sr. we obtain the map of figure 5 from which local flow directions are very clear. the standard error of the regression line (±1.85 m) is likely to include the natural variability of the water table, which gives a backward argument favorable to the neglecting of the diachronous character of well data at section 3. figure-5. surface of the water table computed from the basal surface of the thalwegs of perennial streams and the dem source: yao, et al. [18] 4.2. water occurrence: strata function and thickness in order to target some interesting sites for new population settlements, and given the storage function of the regolith, it is essential to understand the regional control on the distribution of the thickness parameter. the spatial distribution of the residual regolith thickness is obtained by direct kriging of data from 183 boreholes (fig. 6a). despite the low resolution, significant zones emerge from this map and the distribution is compared with the maps of lithology and relief. the thickness, 15 m in average, displays distinct mapped domains. y = 0,92 x 7,00 r2 = 0,95 y = 0,74 x r2 = 0,90 y = 0,004 x 2 + 0,503 x r2 = 0,954 -20 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 a (m) b ( m ) asian review of environmental and earth sciences, 2017, 4(1): 20-27 25 figure-6. a: raw values of the regolith thickness (183 borehole data). b: regolith basal surface (rbs) interpolated from 105 boreholes. kriging by 250 m step with a gaussian variogram. the regolith thickness is obtained (fig. 6c). source: primary data analysis (2017) low thickness (< 25 m) light zones are observed on the highlands of both hillsides of the sassandra, also characterized by higher values of slope giving access to the interfluve limits of the watershed. this is consistent with lower weather ability of the rocks around the inselbergs. another set of low-thickness values are concentrated into a sw-ne alignment passing through okrouyo and meagui within the gneiss and intrusive syenite or binary granite bodies: its trend is n10 and marked as a dotted bold line on fig. 6a. two major gneiss enclaves within migmatite are the sites of main tributary confluents of the sassandra river and display low regolith thickness. high thickness (> 50 m) dark zones are in an alignment trending n30, beginning within migmatite near the sassandra and continued along the anatexis granodiorite: it is marked as a continued bold line on fig. 6a. another high thickness zone is well characterized around oupoyo within migmatite, south of the two major gneiss enclaves. thus, differential weathering as a function of lithology appears to be the main control for the spatial distribution of the regolith. the advocated influence of lithology is consistent with the results of moore, et al. [27] orwalsh and clark [28] under different climatic conditions but similar geology: migmatites display higher regolith thicknesses and yields than foliated plutons. in order to reduce the variance and the nugget effect [17] the base surface of the regolith on the 4,000 km2 study area has been kriged by using a gaussian variogram (fig. 6b). this map explains why regolith thickness na is not correlated with the soil elevation zt. at the time of weathering, the basal surface of the regolith was parallel to the ancient topography. differential erosion has made the present-day morphology of the landscape mainly independent from the inherited weathering profile. then, an improved map of the regolith thickness is obtained (fig. 6c) by subtracting the regolith’s base surface from the topographic surface (dem). on this new map, both the correlation with lithology and the effect of erosion by streams are highlighted. well yields generally give mediocre correlation with other parameters and it is the case here. this is caused by the heterogeneity of the yield values and the interferences between the various influences involved. nevertheless, in our data values of regolith thickness inferior to 10 m do not allow for high yield values (> 10 m3/h) but higher yields arise around the average thickness (15.7 m for this borehole population). thus, wells tapping water under medium or high thickness regolith are the most productive. as the main aquifer component is the fissure layer, the linear yield or yield by well depth must be defined with reference to the well height below the base of the saprolite rather than the total well depth or saturated height [29]. from fig. 7, 95% (respectively 80%) of the cumulative linear yield of a well population is obtained within a 35 m layer (respectively 25 m) under the base surface of the regolith. the first segment of the cumulative curve shows that half the total linear yield comes from a thin horizon (no more than 5 m thick) immediately under the contact and which is likely to drain the regolith. almost all of the other 50% (second segment on the curve) comes from the 5 m to 35 m layer and it is noticeable, with a constant gradient. the gradient changes again between 35 m normalized and 40 m under the base of the regolith and drilling deeper becomes less profitable. figure-7. linear cumulated yield as a function of the effective saturated height under the base of the regolith, 55 boreholes source: yao [25]. asian review of environmental and earth sciences, 2017, 4(1): 20-27 26 5. discussion using the base surface of the perennial streams’ thalwegs, we model the potentiometric surface in the regolith + saprock aquifer. near to the interfluves, the water table is deeper and the hydraulic gradient is lower. this may explain why well yield is often negatively related to local slope, i.e. the rate of change in soil elevation surrounding a well. convergence and merging of the potentiometric surface with the base surface when approaching the perennial streams’ thalwegs is quantified by a linear relationship. in this frame, we question the respective role of the regolith and saprock. the fissure layer or saprock is the most productive part of the hard-rock aquifer, as already shown elsewhere houston and lewis [30]; maréchal, et al. [31]; taylor and howard [32]. following wright [33] effective development of the saprock component requires interaction with storage available in the overlying saturated regolith. we observe as barker, et al. [34] that thicker the regolith, greater the saturated thickness of regolith. moreover, it is generally accepted that the frequency of clusters of subhorizontal fissures within the top of the saprock is greatest where the regolith is thickest. thus the rational in borehole siting is to try to locate the deepest regolith on the assumption that this will maximize yields from both the regolith and the saprock [35]. the average regolith thickness is about 30 m in west africa and only 15 m in the study area. the main phreatic aquifer occurs within the variable layer of saprock. the more fissured and productive parts of the aquifer have transmissivity values up to 100 m2/day. wells in the bedrock tap groundwater from the fissure aquifer mainly in semi-confined conditions under the clayey regolith, or rarely unconfined. yields range from a few m3/day in some upland or slope areas to 43 m3/h in wells adjacent to a perennial stream. however, mapping the regolith thickness [17] is still a new approach in hard rock hydrogeology and is not fully accepted. we advocate that the thickness map obtained from the interpolated base surface of the regolith and the dem is a useful tool for groundwater management which should be integrated for vulnerability mapping [36] and favorability mapping [37] through gis methodology. our improvement of the stratiform model arises from the study of linear yield against depth. decrease in linear yield or hydraulic conductivity is not progressive since we can distinguish three sub-zones sharply contrasted. within each sub-zone, the density of fissures opened to flow is not decreasing with depth. however, dilation of fissures continuously reduces at depth with overburden pressure. so, in contradiction with a recurrent idea in the literature, the role of exhumation pressure release cannot account for these subzones. our observation is rather in conformity with the leading part of mica swelling in the inherited weathering and fissuring profile of the bedrock [17]. for instance, small thickness of the saprolite above syenite (9 m) is mainly attributed to poor weather ability of this rock due to lack of biotite. the two micas or binary granite which contains some biotite has thicker regolith (17 m). the contrasted susceptibility to weathering between different lithologies is not the only control on the formation of the weathering profile: contrasts in tectonic joint and fracture density and in relief amplitude also play a part. as for the role of the local tectonic fracture network, it is often stated that high density of local fractures is favorable to deeper and more penetrative weathering and secondary fissuring, thus leading to higher well yields. we don’t think so. at the time of weathering, opened tectonic joints in uplands allowed through the flow of meteoric waters to the level of the water table deep beneath the hills [19]. once in relief, the fresh bedrock masses tended to remain dry and tectonic fracture density had a conservative function. the late plutons as unfoliated syenite are representative of this case in the study area. at present in this environment, rapid infiltration through thin overburden and diffuse tectonic joints down to the saprock still prevents water from mineralizing. 6. conclusions dealing with the concept of stratiform aquifers in relation with the acquired weathering profile in hard-rocks, the region of soubré (côte d’ivoire, west africa) provides a rich example of how precambrian multiphase magmatism and final tectono-thermal events controlling lithology and jointing, on the other hand, tertiary weathering and quaternary erosion controlling bedrock layering and morphology, are both responsible for present infiltration, groundwater storage and flow within the regional regolith + saprock aquifer. using the base surface of the perennial streams’ thalwegs, we model the potentiometric surface within the regolith + saprock aquifer. the direction of shallow groundwater flow in the study area directly deduces from the local gradient of the potentiometric surface in sub-catchments. wells tapping water under a regolith with medium or high thickness are the most productive, which justifies for regolith thickness mapping as a first rank tool in hydrogeology prospecting. we conclude against the general statement that incremental yield continuously decreases at depth, leading to the idea of lithostatic pressure controlling the openness of fractures more commonly called “sheeting fractures”. at the opposite, the saprock under the regolith is parted into three sub-layers, each one being characterized by a constant density of waterbearing fissures. this highlights the impact of a stratiform weathering profile on the layering of the aquifer. in this frame, the high variability of observed yields is mainly due to thickness heterogeneity of the higher-storative regolith and underlying higher-conductive fissured saprock. references [1] i. yacé, "initiation à la géologie. l’exemple de la côte d’ivoire et de l’afrique de l’ouest. éditions ceda (abidjan), côte d’ivoire," p. 183, 2002. [2] w. f. megahan and j. l. clayton, "saturated hydraulic conductivities of granitic materials of the idaho batholith," journal of hydrology, vol. 84, pp. 167-180, 1986. view at google scholar | view at publisher [3] j. p. faillat, "origine des nitrates dans les nappes de fissures de la zone tropicale humide: exemple de la côte d’ivoire," journal of hydrology, vol. 113, pp. 231-264, 1990. view at google scholar | view at publisher [4] p. p. lenck, "données nouvelles sur l'hydrogéologie des régions à substratum métamorphique ou éruptif. enseignements tirés de la réalisation de 900 forages en côte d'ivoire," comptes rendus de l'académie des sciences series iia earth and planetary science, vol. 285, pp. 497-500, 1977. view at google scholar [5] p. brunner, h. j. h. franssen, l. kgotlhang, p. bauer-gottwein, and w. kinzelbach, "how can remote sensing contribute in ground water modeling?," hydrogeology journal, vol. 15, pp. 5-18, 2007. view at google scholar | view at publisher https://scholar.google.com/scholar?hl=en&q=saturated%20hydraulic%20conductivities%20of%20granitic%20materials%20of%20the%20idaho%20batholith http://dx.doi.org/10.1016/0022-1694(86)90050-8 https://scholar.google.com/scholar?hl=en&q=origine%20des%20nitrates%20dans%20les%20nappes%20de%20fissures%20de%20la%20zone%20tropicale%20humide:%20exemple%20de%20la%20côte%20d’ivoire http://dx.doi.org/10.1016/0022-1694(90)90177-y https://scholar.google.com/scholar?hl=en&q=données%20nouvelles%20sur%20l'hydrogéologie%20des%20régions%20à%20substratum%20métamorphique%20ou%20éruptif.%20enseignements%20tirés%20de%20la%20réalisation%20de%20900%20forages%20en%20côte%20d'ivoire https://scholar.google.com/scholar?hl=en&q=how%20can%20remote%20sensing%20contribute%20in%20ground%20water%20modeling? http://dx.doi.org/10.1007/s10040-006-0127-z asian review of environmental and earth sciences, 2017, 4(1): 20-27 27 [6] j. s. caine and r. a. tomusiak, "brittle structures and their role in controlling porosity and permeability in a complex precambrian crystalline-rock aquifer system in the colorado rocky mountain front range," gsa bulletin, vol. 115, pp. 1410-1424, 2003. view at google scholar | view at publisher [7] m. douglas, "mixing and temporal variations of groundwater inflow at the con mine, yellowknife, canada; an analogue for a radioactive waste repository," unpubl. m.sc. , thesis, dept of geology, university of ottawa, canada, 1997. [8] o. fouché, r. cojean, and m. arnould, "geological and geometrical characterization of natural fractures in a granitic formation from cored boreholes," bulletin of engineering geology and the environment, vol. 60, pp. 231-240, 2001. view at google scholar [9] o. fouché and j. diebolt, "describing the geometry of 3d fracture systems by correcting for linear sampling bias," mathematical geology, vol. 36, pp. 33-63, 2004. view at google scholar | view at publisher [10] s. b. mabee, p. j. curry, and k. c. hardcastle, "correlation of lineaments to ground water inflows in a bedrock tunnel," ground water, vol. 40, pp. 37-43, 2002. view at google scholar | view at publisher [11] a. pouya and o. fouché, "permeability of 3d discontinuity networks: new tensors from boundary-conditioned homogenisation," advances in water resources, vol. 32, pp. 303-314, 2009. view at google scholar | view at publisher [12] j. r. de dreuzy, p. davy, and o. bour, "hydraulic properties of two-dimensional random fracture networks following a power law length distribution: 1-effective connectivity," water resources research, vol. 7, pp. 107-111, 2001. [13] k. f. kouame, a. akaffou, t. lasm, j. r. de dreuzy, p. davy, and o. bour, "simulation des écoulements dans les réservoirs fracturés: application au socle archéen de touba (nord-ouest de la côte d'ivoire)," actes du colloque internationale sitis 05 yaoundé (cameroun), pp. 39-46, 2005. [14] p. lachassagne, r. wyns, and b. dewandel, "the fracture permeability of hard rock aquifers is due neither to tectonics, nor to unloading, but to weathering processes," terra nova, vol. 23, pp. 145-161, 2011. view at google scholar | view at publisher [15] c. faillace, hydrogeology of hard rock in some eastern and western african countries. in: krasny, j. and sharp, j.m. jr (eds), groundwater in fractured rocks. selected papers on hydrogeology 9. london, uk: taylor & francis, 2007. [16] p. j. chilton and s. s. d. foster, "hydrogeological characterization and water-supply potential of basement aquifers in tropical africa," hydrogeology journal, vol. 3, pp. 36-49, 1984. [17] r. wyns, j. m. baltassat, p. lachassagne, a. legchenko, j. vairon, and f. mathieu, "application of snmr soundings for groundwater reserves mapping in weathered basement rocks (brittany, france)," bulletin de la société géologique de france, vol. 175, pp. 21-34, 2004. view at google scholar | view at publisher [18] t. k. yao, o. fouché, k. e. kouadio, m. s. oga, and t. lasm, " modélisation de la surface piézométrique des aquifères fissurés en zone de socle précambrien métamorphisé: cas du bassin versant du sassandra (sud-ouest de la côte d’ivoire)," journal of water science, vol. 28, pp. 105-117, 2015. view at google scholar | view at publisher [19] c. r. twidale and e. m. campbell, "fractures: a double edged sword – a note on fracture density and its importance," zeitschrift für geomorphologie, vol. 37, pp. 459-475, 1993. view at google scholar [20] t. gleeson and k. novakowski, "identifying watershed-scale barriers to groundwater flow: lineaments in the canadian shield," geological society of america bulletin, vol. 121, pp. 333-347, 2009. view at google scholar | view at publisher [21] j. marler and s. ge, "the permeability of the elkhorn fault zone, south park, colorado," ground water, vol. 41, pp. 321-332, 2003. view at google scholar | view at publisher [22] r. fabre, "les effets tectoniques des décrochements n-s sénestres dans les formations volcaniques birimiennes de la région de yaouré, centre de la côte d'ivoire," c.r. acad. sc., paris, tome 300, série ii, n°19, 1985. [23] b. tagini, "esquisse structurale de la côte d’ivoire. essai de géotechnique régionale," thèse, 1971. [24] a. papon and r. lemarchand, "géologie et minéralisation du sud-ouest de la côte d’ivoire," synthèse de l’opération sasca (19621968). sodemi, abidjan, p. 284, 1973. [25] k. t. yao, " hydrodynamisme de l’eau souterraine dans lesaquifères de socle cristallin et cristallophyllien du sud-ouest de la côte d’ivoire: cas du département de soubré. apports de la télédétection, de la géomorphologie et de l’hydrogéochimie," thèse de doct. conservatoire national des arts et métiers,paris, france, 2009. [26] b. dewandel, p. lachassagne, r. wyns, j. c. maréchal, and n. s. krishnamurthy, "a generalized 3-d geological and hydrogeological conceptual model of granite aquifers controlled by single or multiphase weathering," journal of hydrology, vol. 330, pp. 260-284, 2006. view at google scholar | view at publisher [27] r. b. moore, g. e. schwarz, s. f. clark, g. j. walsh, and j. r. degnan, "factors related to well yield in the fractured bedrock aquifer of new hampshire," usgs professional paper, vol. 1660, p. 51, 2002. [28] g. j. walsh and s. f. clark, "contrasting methods of fracture trend characterization in crystalline metamorphic and igneous rocks of the windham quadrangle, new hampshire," northeastern geology and environmental sciences, vol. 22, pp. 109-120, 2000. view at google scholar [29] n. courtois, b. dewandel, p. lachassagne, r. wyns, r. blanchin, s. somé, a. tapsoba, and f. d. bougaïré, "experimental gis hydrogeological mapping of hard-rock aquifers in burkina faso, to help for groundwater management and planning," groundwater and climate in africa, 24-28 june 2008, kampala, uganda, 2008. [30] j. f. t. houston and r. t. lewis, "the victoria province drought relief project ii. borehole yield relationships," ground water, vol. 26, pp. 418-426, 1988. view at google scholar | view at publisher [31] j. c. maréchal, b. dewandel, and k. subrahmanyam, characterization of fracture properties in hard rock aquifer system. in: thangarajan m, 2007, groundwater – resource evaluation, augmentation, contamination, restoration, modeling and management vol. 362: springer, 2007. [32] r. g. taylor and k. w. f. howard, "the influence of tectonic setting on the hydrological characteristics of deeply weathered terrains: evidence from uganda," journal of hydrology, vol. 218, pp. 44-71, 1999. view at google scholar | view at publisher [33] e. p. wright, "the hydrogeology of crystalline basement aquifers in africa," london special publication, vol. 66, pp. 1-27, 1992. view at google scholar | view at publisher [34] r. d. barker, c. c. white, and j. f. t. houston, "borehole siting in an african accelerated drought relief project," geological society special publication, vol. 66, pp. 183-201, 1992. view at google scholar | view at publisher [35] k. w. f. howard and j. karundu, "constraints on the exploitation of basement aquifers in east africa – water balance implications and the role of the regolith," journal of hydrology, vol. 139, pp. 183-196, 1992. view at google scholar | view at publisher [36] s. c. denny, d. m. allen, and j. m. journeay, "drastic-fm: a modified vulnerability mapping method for structurally controlled aquifers in the southern gulf islands, british columbia, canada," hydrogeology journal, vol. 15, pp. 483-493, 2007. view at google scholar | view at publisher [37] v. madrucci, f. taioli, and c. césar de araújo, "groundwater favorability map using gis multicriteria data analysis on crystalline terrain, são paulo state, brazil," journal of hydrology, vol. 357, pp. 153-173, 2008. view at google scholar | view at publisher asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=brittle%20structures%20and%20their%20role%20in%20controlling%20porosity%20and%20permeability%20in%20a%20complex%20precambrian%20crystalline-rock%20aquifer%20system%20in%20the%20colorado%20rocky%20mountain%20front%20range http://dx.doi.org/10.1130/b25088.1 https://scholar.google.com/scholar?hl=en&q=geological%20and%20geometrical%20characterization%20of%20natural%20fractures%20in%20a%20granitic%20formation%20from%20cored%20boreholes https://scholar.google.com/scholar?hl=en&q=describing%20the%20geometry%20of%203d%20fracture%20systems%20by%20correcting%20for%20linear%20sampling%20bias http://dx.doi.org/10.1023/b:matg.0000016229.37309.fd https://scholar.google.com/scholar?hl=en&q=correlation%20of%20lineaments%20to%20ground%20water%20inflows%20in%20a%20bedrock%20tunnel http://dx.doi.org/10.1111/j.1745-6584.2002.tb02489.x https://scholar.google.com/scholar?hl=en&q=permeability%20of%203d%20discontinuity%20networks:%20new%20tensors%20from%20boundary-conditioned%20homogenisation http://dx.doi.org/10.1016/j.advwatres.2008.08.004 https://scholar.google.com/scholar?hl=en&q=the%20fracture%20permeability%20of%20hard%20rock%20aquifers%20is%20due%20neither%20to%20tectonics,%20nor%20to%20unloading,%20but%20to%20weathering%20processes http://dx.doi.org/10.1111/j.1365-3121.2011.00998.x https://scholar.google.com/scholar?hl=en&q=application%20of%20snmr%20soundings%20for%20groundwater%20reserves%20mapping%20in%20weathered%20basement%20rocks%20(brittany,%20france) http://dx.doi.org/10.2113/175.1.21 https://scholar.google.com/scholar?hl=en&q=modélisation%20de%20la%20surface%20piézométrique%20des%20aquifères%20fissurés%20en%20zone%20de%20socle%20précambrien%20métamorphisé:%20cas%20du%20bassin%20versant%20du%20sassandra%20(sud-ouest%20de%20la%20côte%20d’ivoire) http://dx.doi.org/10.7202/1032293ar https://scholar.google.com/scholar?hl=en&q=fractures:%20a%20double%20edged%20sword%20–%20a%20note%20on%20fracture%20density%20and%20its%20importance https://scholar.google.com/scholar?hl=en&q=identifying%20watershed-scale%20barriers%20to%20groundwater%20flow:%20lineaments%20in%20the%20canadian%20shield http://dx.doi.org/10.1130/b26241.1 https://scholar.google.com/scholar?hl=en&q=the%20permeability%20of%20the%20elkhorn%20fault%20zone,%20south%20park,%20colorado http://dx.doi.org/10.1111/j.1745-6584.2003.tb02601.x https://scholar.google.com/scholar?hl=en&q=a%20generalized%203-d%20geological%20and%20hydrogeological%20conceptual%20model%20of%20granite%20aquifers%20controlled%20by%20single%20or%20multiphase%20weathering http://dx.doi.org/10.1016/j.jhydrol.2006.03.026 https://scholar.google.com/scholar?hl=en&q=contrasting%20methods%20of%20fracture%20trend%20characterization%20in%20crystalline%20metamorphic%20and%20igneous%20rocks%20of%20the%20windham%20quadrangle,%20new%20hampshire https://scholar.google.com/scholar?hl=en&q=contrasting%20methods%20of%20fracture%20trend%20characterization%20in%20crystalline%20metamorphic%20and%20igneous%20rocks%20of%20the%20windham%20quadrangle,%20new%20hampshire https://scholar.google.com/scholar?hl=en&q=the%20victoria%20province%20drought%20relief%20project%20ii.%20borehole%20yield%20relationships http://dx.doi.org/10.1111/j.1745-6584.1988.tb00407.x https://scholar.google.com/scholar?hl=en&q= http://dx.doi.org/10.1016/j.sbspro.2013.06.643 https://scholar.google.com/scholar?hl=en&q=the%20hydrogeology%20of%20crystalline%20basement%20aquifers%20in%20africa.%20in:%20wright,%20e.p.%20and%20burgess,%20w.g.%20(eds),%20hydrogeology%20of%20crystalline%20basement%20aquifers%20in%20africa https://scholar.google.com/scholar?hl=en&q=the%20hydrogeology%20of%20crystalline%20basement%20aquifers%20in%20africa.%20in:%20wright,%20e.p.%20and%20burgess,%20w.g.%20(eds),%20hydrogeology%20of%20crystalline%20basement%20aquifers%20in%20africa http://dx.doi.org/10.1144/gsl.sp.1992.066.01.01 https://scholar.google.com/scholar?hl=en&q=borehole%20siting%20in%20an%20african%20accelerated%20drought%20relief%20project.%20in:%20wright,%20e.p.%20and%20burgess,%20w.g.%20(eds),%201992.%20hydrogeology%20of%20crystalline%20basement%20aquifers%20in%20africa, http://dx.doi.org/10.1144/gsl.sp.1992.066.01.09 https://scholar.google.com/scholar?hl=en&q=constraints%20on%20the%20exploitation%20of%20basement%20aquifers%20in%20east%20africa%20–%20water%20balance%20implications%20and%20the%20role%20of%20the%20regolith http://dx.doi.org/10.1016/0022-1694(92)90201-6 https://scholar.google.com/scholar?hl=en&q=drastic-fm:%20a%20modified%20vulnerability%20mapping%20method%20for%20structurally%20controlled%20aquifers%20in%20the%20southern%20gulf%20islands,%20british%20columbia,%20canada https://scholar.google.com/scholar?hl=en&q=drastic-fm:%20a%20modified%20vulnerability%20mapping%20method%20for%20structurally%20controlled%20aquifers%20in%20the%20southern%20gulf%20islands,%20british%20columbia,%20canada http://dx.doi.org/10.1007/s10040-006-0102-8 https://scholar.google.com/scholar?hl=en&q=groundwater%20favorability%20map%20using%20gis%20multicriteria%20data%20analysis%20on%20crystalline%20terrain,%20são%20paulo%20state,%20brazil http://dx.doi.org/10.1016/j.jhydrol.2008.03.026 phytodiversity of vegetation of khadgawan block, dist-koria (chhattisgarh) india asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 3, 61-65, 2014 http://www.asianonlinejournals.com/index.php/arees * corresponding author 61 phytodiversity of vegetation of khadgawan block, distkoria (chhattisgarh) india mantosh kumar sinha 1* --deepima sinha 2 1 k.r. technical college, sarguja university, ambikapur (chhattisgarh) india 2 sarguja vishwavidyalaya engineering college lakhanpur ambikapur (chhattisgarh) india abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 62 2. materials and methods ............................................................................................................................................................. 62 3. results & discussion ................................................................................................................................................................. 62 4. conclusion .................................................................................................................................................................................. 62 references ...................................................................................................................................................................................... 64 the district koria has a very rich flora exhibiting diversity specially of medicinal plants. there is no comprehensive description of the flora of the district is available . the district has a tribal population using enormous range of plants for their basic needs, sustenance and livelihood. keeping these points in view the present paper deals with diversity of the medicinal plants of the district and their ecological status. vegetational analysis of khadgawan block revealed some interesting observations on phytosociological characters enumerate 94 medicinal plants were recorded. the common plant species showing maximum frequency were tribulus terrestris (90%), vicia sativa (80%) and jatropha curcas, cleome gynandra and blumea lacera (70%). population-wise cleome gynandra and vicia sativa were high showing maximum density of 66.6 and 66.3 respectively. cleome gynandra was most abundantly found. other abundantly found species at khadgawan were thysanolaena agrostis and cymbopogon martini. at this site, caesalpinia bonducella, hemidesmus indicus, mimosa pudica, salmalia malabaricum were the plants which showed minimum frequency values of only 20%. minimum density and abundance was exhibited by leucas cephalotes, dioscorea bulbifera and salmalia malabaricum . acorus calamus, caesalpinia bonducella, amomum subulatum and hemidesmus indicus were the rare species at this site. keywords: phytosociology, khadgawan, vegetation, % frequency. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(3): 61-65 62 1. introduction india contains about 8% of world's biodiversity on 2% of the earth's surface, making it one of the 12 mega diversity countries in the world. this is based on the species richness and levels of endemism recorded in a wide range of taxa of both plants and animals. chhattisgarh, the 26th state of the country, has ample variation in physical and cultural features. it has about 44% of its total geographical area covered with forests. it enjoys hot and humid climate and gains rainfall from both north-east and south-west monsoon. koria district in chhattisgarh is very rich in natural vegetation and biological wealth. the district lies between 22 0 58’ to 23 0 49’ north latitude and 81 0 33’ to 82 0 45’ east longitude and has a forest area of 81.23%. average rainfall is 121.36 cm. and annual mean temperature is 240c. the district is dominated by upper gondwana rocks which are rich in deposition of coal. the vegetation particularly the forests have not been explored fully excepting a few reports from the forest department tiwari pranesh [1] there is no report on the rich forest flora of the district. keeping these points in view the present investigation was planned to enumerated phytosociological analysis of vegetation of medicinal plants belonging to khadgawan block. 2. materials and methods extensive field survey was undertaken during 2006 to 2008.the phytodiversity of tropical dry deciduous forests was explored. the district comprises 5 development block, namely, baikunthpur,sonhat, manendragarh, khadgavan and bharatpur. this study was done in the khadgawan block of the district. khadgawan block included study sites which were widely separated from each other, encompassing an area of 30 km 2 . study sites were visited of frequent intervals and a thorough sampling was done to document the species diversity. the plant specimens were preserved, identified and a herbarium has been prepared. identification of medicinal plants species was primarily done by gathering local information regarding availability and utilization of various wild medicinally important plants. the sampling sites were selected randomly these are podidih, peeparbahra, jilda, duggi, kadambahra, podi, bachra, bardar, chopan, bharda, pendari, mangora, kodangi, and kanharbahra. (fig-1) the phytosociological characters, such as, % frequency, density and abundance were also recorded as per method described by mishra [2]. 3. results & discussion phytosociological observations on medicinal plants belonging to khadgawan block enumerated , 94 medicinal plants were recorded. the common plant species showing maximum frequency were tribulus terrestris (90%), vicia sativa (80%) and jatropha curcas, cleome gynandra and blumea lacera (70%). population-wise cleome gynandra and vicia sativa were high showing maximum density of 66.6 and 66.3 respectively. cleome gynandra was most abundantly found. other abundantly found species at khadgawan were thysanolaena agrostis and cymbopogon martini. at this site, caesalpinia bonducella, hemidesmus indicus, mimosa pudica, salmalia malabaricum were the plants which showed minimum frequency values of only 20%. minimum density and abundance was exhibited by leucas cephalotes, dioscorea bulbifera and salmalia malabaricum . acorus calamus, caesalpinia bonducella, amomum subulatum and hemidesmus indicus were the rare species at this site. (table-1). however, the results clearly indicate a high degree of diversity and the community is a tropical dry deciduous type of sal forest. negi and sunil [3] have enumerated phyto-sociological studies of a traditional reserve forest, thal ke dhar, pithoragarh, central himalayas (india). they have documented phytosociological study in thal ke dhar sacred forest to understand the structure, regene-ration potential and conservation status. [3] kharkwal geeta, et al. [4] have described phytodiversity and growth form in relation to altitudinal gradient in the central himalayan (kumaun) region of india. they noted that a total of 2487 species were recorded, of which, 276 were trees, 355 shrubs, 112 climbers and 1744 herbs. the study concludes that the distri-bution and species richness pattern in this region largely depends on the altitude and climatic variables like largely depends on the altitude and climatic variables like rainfall, temperature etc. [4] kumar ashish, et al. [5] have analysed phytosociological characteristics and diversity patterns of tropical forest tree species in garo hills, western meghalaya, north-east india. kumar ashish, et al. [5] thakur and khare [6] have reported tectona grandis as dominant tree species in forest vegetation of sagar district on the basis of i.v.i. in present study, analysis has been done especially emphasizing medicinal plants [6]. pokhariyal, et al. [7] have analysed the comparative studies on species richness, diversity and composition of anogeissus latifolius mixed forest in phakot and pathari rao watersheds of garhwal himalyas. they have compared the tree species richness in the two watersheds and revealed that distribution and species richness pattern in phakot and pathari rao watersheds were more or less similar. a total of 87 spp. [7]. shameem and kangroo [8] have studied to investigate the comparative assessment of edaphic factors and phytodiversity of herbaceous vegetation on seasonal basis spring (march to may), summer (june to august), autumn (september to november) and winter (december to february), at two different ecosystems in lower dachigam national park, kashmir himalaya.[8]. shaheen hamayun and shinwari zabta [9] they have studied that hindukush himalayas (hkh) is one of the world’s richest biodiversity region hosting 4 global biodiversity hotspots, 60 ecoregions and 488 protected areas. [9]. 4. conclusion the result in the present study clearly show that the flora is very rich floristically which may be attributed to its varied topography and variation in climatic conditions. species showing high frequency and low abundance were asian review of environmental and earth sciences, 2014, 1(3): 61-65 63 attributed to a status of regular distribution and species showing low frequency and high abundance were attributed to a status of showing contagious distribution. table-1. phytosociological observation of medicinal plants of khadgawan block s.no. botanical name life form %frequency density abundance ecological status distribution r/c 1. acorus calamus l. h 20 3.7 18.5 rare r r 2. alangium lamarckii thw. t 60 13.2 22 often r 3. alstonia scholaris brown. t 30 2.5 8.33 seldom r 4. amomum subulatum roxb. s 20 3.1 15.5 rare r r 5. amorphophallus campanulatus roxb. h 20 3.4 17 rare r r 6. anamirta cocculus w.&.a. c 50 6.4 12.8 often r 7. artemisia maritima linn. h 60 15.1 25.16 often r 8. barleria cristata l. h 40 15.3 30.6 seldom r 9. bauhinia purpurea l. s 60 12.4 20.66 often r 10. bauhinia variegata l. t 30 3.2 10.66 seldom r 11. blumea lacera dc. h 70 26.3 37.57 mostly r 12. bryophyllum calycinum salis. h 50 29.1 58.2 often c 13. buchanania lanzan spreng. t 20 3.5 17.5 rare r r 14. butea monosperma lamk. t 40 16.9 42.25 seldom c 15. caesalpinia bonducella flem. s 20 7.5 37.5 rare c c 16. canna indica l. h 40 5.4 13.5 seldom r 17. cannabis corniculata l. s 40 8.5 14.16 seldom r 18. carissa spinarum l. s 30 33.5 41.87 seldom c 19. cassia fistula l. t 50 10.5 26.25 often r 20. cassia sophera l. s 50 4.3 8.6 often r 21. centella asiatica l. h 50 21.9 36.5 often r 22. chloroxylon swietenia dc. t 50 25.9 51.8 often c 23. cleome gynandra l. h 70 66.6 95.14 mostly c c 24. clitoria ternatea l. c 20 3.3 16.5 rare r r 25. cochlospermum religiosum dc. t 30 5.4 18 seldom r 26. colebrookia oppositifolia smith t 50 6.3 12.6 often r 27. coleus aromaticus roxb. h 30 10.4 34.66 seldom c 28. corchorus trilocularis l. s 40 13.9 34.75 seldom r r 29. cryptolepsis buchanani roem. s 40 7.7 19.25 seldom r r 30. curcuma angustifolia roxb. h 50 11.1 22.2 often r r 31. curcuma aromatica salisb. h 40 23.5 58.75 seldom c c 32. cuscuta reflexa roxb. h 20 7.7 38.5 rare c c 33. cymbopogon martini stapf. h 40 45.6 114 seldom c c 34. cyperus rotundus l. h 50 29.8 59.6 often c 35. cyperus scariosus br. h 60 44.5 74.16 often c 36. dalbergia latifolia roxb. t 50 12.1 24.2 often r 37. dioscorea bulbifera l. c 30 2.3 7.66 seldom r 38. diospyros melanoxylon roxb. t 40 34.4 43 seldom c 39. dodonaea viscosa l. h 50 33.5 67 often c 40. dryopteris crenata christ. h 30 6 20 seldom r 41. eclipta alba hassk. h 60 20.4 34 often r 42. euphorbia neriifolia l. s 50 13.2 26.4 often r 43. euphorbia tirucalli l. s 60 18.3 30.5 often r 44. flemingia nana roxb. h 40 5.5 13.75 seldom r 45. garcinia indica l. t 50 6.2 12.4 often r 46. helicteres isora l. s 40 7.8 19.5 seldom r 47. hemidesmus indicus br. h 20 3.3 11 rare r r 48. holoptelea integrifolia planch. t 60 7.2 12 often r 49. hygrophila augustifolia r.br. h 60 24.3 40.5 often r 50. hyptis suaveolens poit s 30 13 43.33 seldom c c continue asian review of environmental and earth sciences, 2014, 1(3): 61-65 64 51.ipomoea mauritiana lam. h 40 16.9 42.25 seldom c 52. jatropha curcas l. s 70 35 50 mostly r 53. jatropha gossypifolia l. s 50 17.4 34.8 often r 54. jussiaea suffruticosa l. h 50 26.2 52.4 often c 55. lawsonia inermis l. s 60 48.2 80.33 often c 56. leucas cephalotes spreng. s 30 1 10 seldom r 57. luffa aegyptiaca mill. c 70 8.4 12 mostly r 58. melia azedarach l. t 30 3.7 12.33 seldom r 59. mimosa pudica l. h 20 7.2 36 rare c c 60. murraya koenigii spreng. s 60 25.5 42.5 often r 62. ocimum basilicum l. h 60 32.6 54.33 often r 63. ougeinia dalbergioides benth. t 50 8.1 16.2 often r 64. oxystelma esculentum br. h 30 7 35 seldom c 65. pedalium murex l. s 50 13.1 26.2 often r 66. phyllanthus niruri l. h 40 18.7 46.75 seldom c 67. picrorhiza kurroa benth. h 60 28.7 47.83 often r 68. piper longum l. h 40 6 15 seldom r 69. pterospermum acerifolium willd. t 30 2.3 7.66 seldom r 70. pueraria tuberosa dc. c 30 2.7 9 seldom r 71. quisqualis indica l. h 40 26.3 65.75 seldom c c 72. randia dumetorum lamk. s 30 8.7 29 seldom r 73. salmalia malabaricum dc. t 20 1.5 7.5 rare r r 74. shorea robusta l. t 50 34.1 68.2 often c c 75. smilax zeylanica l. c 30 5.4 13.5 seldom r 76. sphaeranthus indicus l. h 40 8.4 21 seldom r 77. spilanthes acmella l. h 20 3 15 rare r r 78. stevia rebaudiana bertoni. h 30 6.2 20.66 seldom r 79. tectona grandis l. t 30 3.1 10.33 seldom r r 80. terminalia arjuna w.&a. t 30 10 6.66 seldom r 81. terminalia belerica roxb. t 30 4.5 15 seldom r 82. thalictrum foliolosum dc. h 40 10 25 seldom r 83. thysanolaena agrostis nees. h 40 55.4 138.5 seldom c c 84. tribulus terrestris l. h 90 46.4 51.55 constantly r 85. triumfetta rhomboidea jacq. h 60 21.4 35.66 often r r 86. vernonia anthelminticum willd. h 50 22 44 often r r 87. vernonia cinerea less. h 50 24.7 49.4 often r r 88. vicia sativa l. c 80 66.3 82.87 mostly c c 89. vicoa auriculata cass. h 50 23.2 46.4 often r r 90. vitex negundo l. t 40 5.5 13.75 seldom r 91. wedelia calendulacea less. h 20 7.1 35.5 rare c c 92. woodfordia fruticosa kurz. s 60 33.1 47.28 often r 93. xanthium strumarium l. h 30 14 46.66 seldom c 94. zizyphus xylopyra willd. t 30 9.7 32.33 seldom c references [1] tiwari pranesh, "working plan for koria forest division surguja circle," chhattisgarh forest department, vol. 1, 1992. [2] r. mishra, ecology work book. new delhi: oxford and ibh publication co., 1968. [3] s. c. negi and n. sunil, "phytosociological studies of a traditional reserve forest thal ke dhar, pithoragarh, central himalayas (india)," indian forester, vol. 131, pp. 519-534, 2005. [4] kharkwal geeta, poonam mehrotra, y. s. rawat, and y. p. s. pangtey, "phyto-diversity and growth form in relation to altitudinal gradient in the central himalayan (kumaun) region of india," curr. sci., vol. 89, pp. 873-878, 2005. [5] g. kumar ashish, bruce marcot, and ajai saxena, "tree species diversity and distribution patterns in tropical forests of garo hills," curr. sci., vol. 91, pp. 1370-1381, 2006. [6] a. s. thakur and p. k. khare, "species diversity and composition of forest vegetation of sagar district in central india," the indian forester, vol. 134, pp. 801-813, 2008. [7] p. pokhariyal, v. naiathani, s. dasgupta, and n. p. todaria, "comparative studes on species richness, diversity and composition of anogeissus latifolius mixed forest in phakot and pathari rao watersheds of garhwal himalaya," curr. sci., vol. 97, pp. 1349-1355, 2009. [8] s. a. shameem and i. n. kangroo, "comparative assessment of edaphic features and phytodiversity in lower dachigam national park kashmir himalaya, india," african journal of environ. science and technology, vol. 5, pp. 972-984, 2011. [9] shaheen hamayun and k. shinwari zabta, "phytodiversity and endemic richness of karambar lake vegetation from chitral, hindukush himalaya," pak. j. bot., vol. 44, pp. 15-20, 2012. asian review of environmental and earth sciences, 2014, 1(3): 61-65 65 figure-1. khadgawan block showing study sites views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 2, 25-29, 2014 http://www.asianonlinejournals.com/index.php/arees 25 perspective: the environmental implications of oil theft and artisanal refining in the niger delta region obenade, moses 1 --amangabara, gordon tami 2 1 department of geography and environmental science, university of calabar; national centre for technology management (nacetem), south-south office, bayelsa state, nigeria 2 department of environmental technology, federal university of technology, owerri, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction the niger delta region is the crude oil and natural gas hub of nigeria with several networks of product pipelines (both surface and subsurface) which has created a social problem of vandalization of the product pipelines for the purpose of stealing the product. oil theft and artisanal refining in the niger delta are massive and growing problems, it is estimated that between 200,000 and 300,000 barrels of oil is lost daily to theft, known in the country as illegal bunkering. the majority of the stolen crude is taken to large ocean-going tankers waiting offshore, which export the oil to refineries outside the country. some of these tankers reportedly meet in mid-ocean to share and blend stolen oil, thus making it more difficult to identify, while the precise contours of the international networks may be difficult to discern; the rest of the stolen oil goes into artisanal refining which is the processing of the stolen crude in makeshift individual facilities into low quality petroleum products. fig-1.map of nigeria showing the niger delta region source: ite [1] illegal oil bunkering and artisanal refining are on the rise in various communities in the niger delta and worsen the ecological destruction and social conflict caused by the oil industry. this review examines the concept of oil theft and artisanal refining and their environmental implications and concluded that oil theft and artisanal refining in the niger delta are massive and growing problems. it is estimated that between 200,000 and 300,000 barrels of oil is lost daily to theft, known in the country as illegal bunkering. the majority of the stolen crude oil is taken to large ocean-going tankers waiting offshore, which export the oil to refineries outside the country to the rest of the world. stolen oil is also refined in makeshift individual facilities into low quality petroleum products. the authors conclude that while acknowledging the seeming social and economic advantages that artisanal refining brings to the host communities, and the argument that artisanal refining actually represents an opportunity which could be harnessed by the government to enhance economic and social opportunities in an environment of high unemployment and poverty, especially in the oil-producing areas of the country, the disadvantages far outweigh the seeming advantages both to the community and the environment at large. keywords: artisanal refining, oil theft, crude oil, niger delta, environment, pollution, degradation, bunkering, pipelines. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(2): 25-29 26 many of the operators and oil thieves who are directly and indirectly involved in the bunkering and refining, make money in this multi-billion dollar business, they have secured social license from host communities by launching social welfare programs in the region; like drug cartels in mexico, of militant jihadists in pakistan and warlords in somalia [2]. the militias in the region gained relevance by offering social services such as schools, security, food and education where government is unable or unwilling to deliver these services. in addition to the hard security challenge, oil theft has grown into a cancer that undermines the safety of the environment; the local oil producing communities suffer an incremental social death caused by a complex combination of economic and environmental complications, the environmental impacts oil theft and artisanal refining causes is clearly visible. no doubt oil bunkering and artisanal refining are on the rise in various communities in the niger delta and worsen the ecological destruction and social conflict caused by the oil industry. this review examines the activities and impacts of oil theft and artisanal refining on the niger delta environment linking the discourse to the debate on development benefits of artisanal mining in developing countries. the author concludes that while acknowledging the seeming social and economic advantages that it brings to host communities and locals and the argument that artisanal refining actually represents an opportunity which could be harnessed by the government to enhance economic and social opportunities in an environment of high unemployment and poverty, especially in the oil-producing areas of the country. the disadvantages far outweigh the seeming advantages both to the community and the environment at large. 2. oil theft oil theft or illegal bunkering as it is known in nigeria is an ‗organized‘ theft of crude oil from product pipelines through the use of improvised conduits and direct pumping from oil well heads into barges by criminal syndicates. it may appear chaotic, but there is structure and strategy to this menace. it is a wellfinanced and highly organized criminal phenomenon – a parallel industry with a developed supply chain and growing sophistication. it involves trained artisans who break into high pressure pipelines, using welded valves and other complex instruments to siphon oil mostly in the night. boat yards help construct and supply barges to the thieves to transport crude oil around the creeks. local women supply firewood etc to workers at the camp. many of the people involved in oil theft work for local markets, poorly refining products for communities desperate for affordable sources of energy. some – far larger in scale, organization and significance – are managing an international export business with tentacles across the globe. oil theft has grown in scale since the end of organized insurgency in the niger delta and the introduction of the amnesty program in june 2009, their scale has grown beyond recognition. that year, the un estimated thieves stole around 150,000 barrels of oil a day. by mid 2012, the nigerian government estimated as many as 400,000 barrels were being stolen each day, costing the nation up to $1 billion per month in lost revenues. this escalation is unprecedented [3]. oil is spilled at the point of siphoning, during transportation to camps and waiting vessels and at the camps (local refineries). some of the oil stolen (about 25%) is delivered to small scale rudimentary refineries in the creeks and mangroves where it is heated in fabricated metal stills or drums to produce low grade diesel fuel. it‘s likely as much as 80% of the heavy end of crude cannot be refined and are just dumped into the environment. it is not possible to know how much of stolen oil is spilled but considering all the sources of spill as highlighted above, damage to the environment is enormous. 3. artisanal refining artisanal refining is the process of procuring stolen crude oil and in refining them in the so-called ―bush‖ refineries with the use of local resources and skills (drawing on the indigenous technology used to distil locally made gin – ogogoro or kaikai). the basic materials typically involves rudimentary illegal stills – often metal pipes and drums welded together – in which crude oil is boiled and the resultant fumes are collected, cooled and condensed in tanks to be used locally for lighting, energy or transport [4]. the basic refining technique, first used during the biafran civil war, was resurrected and modernized by members of militant camps between 2005 and 2009, providing fuel and cash to support the niger delta insurgency. after an amnesty deal for militants was brokered in 2009, those in the militant camps returned to their villages, taking their knowledge of refining with them. as a result of the failure to prevent this at an early stage and the huge commercial rewards available, the trade grew and became more entrenched in the community. on the average, typical artisanal refinery produces about forty to sixty drums of diesel a day. sites vary in size and reflect different levels of investment. small scale sites tend to attract women and people with very low levels of capital to invest, whilst larger scale sites involve entrepreneurs who own relatively large production sites. fig-1. (a) artisanal refining of illegal crude oil asian review of environmental and earth sciences, 2014, 1(2): 25-29 27 (b) site of illegal crude refining source [5] severe damage is done to the environment as a result of artisanal refining. the refining process leads to a significant quantity of wastage being dumped in rivers and streams or on land – two drums of crude oil translate into one drum of product once refined. the distilleries (fig 2) are heated on open fires fed by crude oil that is tipped into pits in the ground. as a reasonable quantity of the oil burns away, some seeps into the ground during the process of refining. the resulting oil spills from broken pipes and wastes from tens of thousands of makeshift refineries combine to produce enormous environmental pollution on land and in the creeks. apart from the high risk of selfharm from artisanal refining – a large number of accidents, fires and explosions occur [4]. 4. the environmental impacts according to ogbuagu, et al. [6] , it has been reported that petroleum refining contributes solid, liquid, and gaseous wastes in the environment. some of these wastes could contain toxic components such as the polynuclear aromatic hydrocarbons (pahs), which have been reported to be the real contaminants of oil and most abundant of the main hydrocarbons found in the crude oil mixture [7] . once introduced in the environment, pahs could be stable for as short as 48 hours (e.g. naphthalene) or as long as 400 days (e.g. fluoranthene) in soils [8] . they thus, resist degradation and, remain persistent in sediments and when in organisms, could accumulate in adipose tissues and further transferred up the trophic chain or web [9]. lyons, et al. [10] opines that acute exposures to aromatic hydrocarbons, which are common constituents of oil, are known to cause respiratory symptoms and high molecular weight pahs are of significant concern because of the mutagenicity, carcinogenicity and bioaccumulation in organic tissues due to their lipophilic character [11]. increasing evidence, mainly from the prestige oil spill, suggests that human population exposed to risks may experience long term respiratory effects and chromosomal damage [ odr guez-trigo, et al. [12], zock, et al. [13],perez-cadahia, et al. [14]]. it has also been widely reported that exposure to pahs can cause skin damage, bronchial symptoms in children and has been implicated in the pathogenesis of skin tumours as well as chromosomal disorders. evidence of acute exposure to oil spill around the world demonstrates the potential adverse health effects associated with petroleum–contaminated environment. some host communities like the ogonis have suffered from significant environmental degradation and health impacts including increase in respiratory diseases and cancer cases [15]. according to [4], the health of several ogoni communities has been severely compromised as a result of surface and groundwater contamination associated with petroleum exploration and production operations. however, there appears to be little information on potential human health risks of exposure to oil pollution in the oil–producing communities in the niger delta region over the past five decades. there is high probability for a wide range of toxic responses in many host communities of the niger delta including behavioural abnormalities, respiratory diseases, suppressed growth, induced or inhibited enzyme, adverse physiological responses, blood disorders, negative reproductive outcomes, reduced immunity to disease and parasites, and cancers of the various organs [16]. fig-3.environmental degradation around campsite source: [17] oil pollution in many intertidal creeks have left mangroves denuded of leaves and stems, leaving roots coated in a bitumen-like substance sometimes 1 cm or more thick. mangroves are spawning areas for fish and nurseries for juvenile fish and the extensive pollution of these areas is impacting the fish life-cycle [4]. from the unep study, it was found that fish tend to leave polluted areas in search of cleaner water, and fishermen must therefore also move to less contaminated areas in search of fish. asian review of environmental and earth sciences, 2014, 1(2): 25-29 28 despite community concerns about the quality of fish, the results show that the accumulation of hydrocarbons in fish is not a serious health issue in the region but that the fisheries sector is suffering due to the destruction of fish habitat in the mangroves and highly persistent contamination of many of the creeks, making them unsuitable for fishing. where a number of entrepreneurs had set up fish farms in or close to the creeks, their businesses have been ruined by an ever-present layer of floating oil. any crop in areas directly impacted by oil spills will be damaged, and root crops, such as cassava, will become unusable. when farming recommences, plants generally show signs of stress and yields are reportedly lower than in non-impacted areas [4].when an oil spill occurs on land, fires often break out, killing vegetation and creating a crust over the land, making remediation or re-vegetation difficult. unep in its environmental assessment of ogoniland observed that bodo west, in gokana local government area, there was an increase in artisanal refining between 2007 and 2011 has been accompanied by a 10% loss of healthy mangrove cover, or 307,381 m 2 , and that if allowed to continue unabated, this may lead to irreversible loss of mangrove habitat in this area. unep in its report clearly stated that wetlands around ogoniland are highly degraded and facing disintegration as a result of oil pollution. the study concludes that while it is technically feasible to restore effective ecosystem functioning of the wetlands, this will only be possible if technical and political initiatives are undertaken [4]. most people in the niger delta communities are exposed to petroleum hydrocarbons in outdoor air and drinking water, sometimes at elevated concentrations, according to amangabara and njoku [18] the water table around bolo and its environs is already being impacted by crude oil related activities; they are also exposed through dermal contacts from contaminated soil, sediments and surface water. since average life expectancy in nigeria is less than 50 years, it is a fair assumption that most members of the current niger delta communities have lived with chronic oil pollution throughout their lives. 4. summary and conclusion environmental degradation is the most visible and direct impact of illegal refining and oil theft. photographic evidence gathered at sites visited across delta, bayelsa and rivers states show the terrible impacts of artisanal refining to the local environment. vegetation is visibly affected by the resulting pollution; crude saturates the mangroves and oil disturbs the surface water. the environmental destruction associated with illegal oil refining harms traditional livelihoods tied to the land and water. oil pollution is a significant barrier to cooperative integrated fish farming, one of the few businesses that could provide sustainable employment and incomes. nigeria spent over n100 billion on the importation of frozen fish in 2010, some of which is necessary for niger delta communities to replace the fish they once caught [17]. oil theft and artisanal refining has significant health risks for those involved and the environment as well. the handling and heating of the crude oil pollutes the air. the camps have a toxic feel and the health impacts of those working there are unknown. communities are constantly exposed to inhalation of poisonous gases, causing coughing and breathing problems. however, many are in denial about the potential medium to long-term health implications because of the short term economic gains. references [1] u. e. ite, "multinationals and corporate social responsibility in developing countries: a case study of nigeria," corporate social responsibility and environmental management vol. 11, pp. 1-11, 2013. [2] t. attah, "oil theft and artisanal (illegal) refining in nigeria – scale, impacts and the need for a multi-dimensional response," chatham house – gulf of guinea security conference, london, 2012. [3] shell petroleum development company of nigeria limited [spdc], "annual report," 2010. [4] unep, environmental assessment of ogoniland, nairobi. kenya: united nations environment programme, 2011. [5] international institute for petroleum energy law and policy (iipelp), "crude theft: economic implication & mitigation strategies." available www.oceanguy.com/wp-content/upoads/2011/03/law-2.jpg [accessed 13/06/2014], 2011. [6] d. h. ogbuagu, c. g. okoli, c. l. gilbert, and s. madu, "determination of the contamination of groundwater sources in okrika mainland with polynuclear aromatic hydrocarbons (pahs)," british journal of environment & climate change, vol. 1, pp. 90-102, 2011. [7] m. k. z. el-deeb and h. i. emara, "polycyclic aromatic hydrocarbons and aromatic plasticizer materials in the seawater of alexandria coastal area. ," egyptian j. of aquat res., vol. 31, pp. 15-24, 2005. [8] d. a. martens and j. t. frankenberger, "enhanced degradation of polycyclic aromatic hydrocarbons in soil treated with an advanced oxidative process—fenton‘s reagent," journal of soil contamination, vol. 4, pp. 175-190, 1995. [9] j. c. decker, "potential health hazards of toxic residues in sludge. in sludge-health risk of land application," ann. arbon. sci. publ. inc, pp. 85-102, 1981. [10] r. a. lyons, j. m. temple, d. evans, d. l. fone, and s. r. palmer, "acute health effects of the sea empress oil spill," journal of epidemiology and community health, vol. 53, pp. 306-310, 1999. [11] a. e. ite and k. t. semple, biodegradation of petroleum hydrocarbons in contaminated soils, microbial biotechnology: energy and environment. wallingford, oxfordshire: cab international, 2012. [12] g. rodr guezrigo, . . ock, . ozoodr guez, . . mez, . onyarch, . ouso, . . oll, . . erea, . . nt , . fuster, and j. a. barberà, "health changes in fishermen 2 years after clean-up of the prestige oil spill," annals of internal medicine, vol. 153, pp. 489-498, 2010. [13] j. p. zock, g. rodriguez-trigo, f. pozo-rodriguez, j. a. barbera, l. bouso, y. torralba, j. m. anto, f. p. gomez, c. fuster, h. verea, and s. e. p. s. group, "prolonged respiratory symptoms in clean-up workers of the prestige oil spill," american journal of respiratory and critical care medicine, vol. 176, pp. 610-616, 2007. [14] b. perez-cadahia, b. laffon, v. valdiglesias, e. pasaro, and j. mendez, "cytogenetic effects induced by prestige oil on human populations: the role of polymorphisms in genes involved in metabolism and dna repair," mutation research, vol. 653, pp. 117123, 2008. [15] i. blankson, public relations in sub-saharan africa," global public relations: spanning borders, spanning cultures. london: routledge, 2009. [16] j. nriagu, oil industry and the health of communities in the niger delta of nigeria," encyclopedia of environmental health. burlington: elsevier, 2011. [17] sdn, "illegal oil refining in the niger delta." available www.stakeholderdemocracy.org, 2013. http://www.oceanguy.com/wp-content/upoads/2011/03/law-2.jpg http://www.stakeholderdemocracy.org,/ asian review of environmental and earth sciences, 2014, 1(2): 25-29 29 [18] g. t. amangabara and j. d. njoku, "assessing groundwater vulnerability to the activities of artisanal refining in bolo and environs, ogu/bolo local government area of rivers state; nigeria," british journal of environment and climate change, vol. 2, pp. 28-36, 2012. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. 34 asian review of environmental and earth sciences vol. 5, no. 1, 34-46, 2018 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.34.46 © 2018 by the authors; licensee asian online journal publishing group water balance model: implications for groundwater recharge estimation in data scarce arid catchment, northern ethiopia nata t. tafesse1  michiele gebrehiwet2 solomon habtu3 berhanu f. alemaw4 ( corresponding author) 1,4department of geology, university of botswana, botswana 2,3department of land resources management and environmental protection, mekelle university, ethiopia abstract the paper presents results related to water balance model of the gumselassa catchment (28.1 km2), tigray, northern ethiopia. the catchment includes a small dam called gumselassa dam having an effective watershed area of 22.14 km2 with reservoir capacity of 1.92 x 106 m3 and command area of about 1sq. km. the hydrology of the area was characterized on the basis of land use, soil, slope and climatic parameters. different methods were employed in this study: rainfall coefficient method was used to determine monthly distribution of rainfall; penman method to calculate evaporation from the reservoir; thornthwaite method and thornthwaite water balance model to determine potential and actual evapotranspiration; runoff coefficient method to estimate runoff; and, the water balance model was used to quantify the recharge. the catchment is characterized by one rainy season (three months) and two dry seasons (nine months) during the year. the mean annual rainfall of the catchment is 485.89 mm. the total annual water loss by evaporation from the reservoir is 1263.27 mm. the mean annual actual evapotranspiration of the effective watershed area one and two is 318.57 mm and 310.27 mm, respectively. the mean annual actual evapotranspiration of the water contributing area 1 and 2 to the command area is 337.06 mm and 355.29 mm, respectively. the mean annual actual evapotranspiration of the command area is 319.3 mm. the mean annual runoff generated from the effective watershed area one and two is 1.167 and 0.44 million cubic meters, respectively. the mean annual runoff generated from the water contributing area 1 and 2 to the command area is 0.048 and 0.349 million cubic meters, respectively. the mean annual runoff generated from the command area is 0.0875 million cubic meters. the total amount of water which is actually available to recharge the groundwater within the catchment is 4.065 million cubic meters, and any application of water for irrigation from the reservoir should take into account this readily available water. keywords: command area, evapotranspiration, recharge, reservoir, runoff. citation | nata t. tafesse; michiele gebrehiwet; solomon habtu; berhanu f. alemaw (2018). water balance model: implications for groundwater recharge estimation in data scarce arid catchment, northern ethiopia. asian review of environmental and earth sciences, 5(1): 34-46. history: received: 10 august 2018 revised: 17 september 2018 accepted: 19 october 2018 published: 23 november 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: this research work was financed by eau4food project (european union and african union cooperative research). the support provided in the form funding is duly acknowledged. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ........................................................................................................................................................................................................... 35 2. methodology .......................................................................................................................................................................................................... 35 3. results and discussions ....................................................................................................................................................................................... 39 4. conclusions ............................................................................................................................................................................................................ 45 references ................................................................................................................................................................................................................... 45 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.34.46&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/708 https://orcid.org/0000-0002-4687-7540 http://asianonlinejournals.com/index.php/arees/article/view/708 https://orcid.org/0000-0002-4687-7540 http://asianonlinejournals.com/index.php/arees/article/view/708 https://orcid.org/0000-0002-4687-7540 asian review of environmental and earth sciences, 2018, 5(1): 34-46 35 1. introduction 1.1. general groundwater recharge is a fundamental component in the water balance of any watershed. groundwater recharge may be explained as the process whereby the amount of water present in or flowing through the interstices of the sub-soil increases by natural or artificial means. the amount of water that may be extracted from an aquifer without causing depletion is primarily dependent upon the groundwater recharge. rainfall is the principal source for replenishment of moisture in the soil water system and recharge of groundwater. other sources include recharge from rivers, streams, reservoirs, irrigation water etc. groundwater recharge occurring in smalland large-scale and spatially and temporally is influenced by factors such as climate, soil characteristics, vegetation, geology, slope and thickness of permeable unsaturated zones [1, 2]. because groundwater is such a valuable resource, it is important to understand and know the groundwater recharge for sustainable utilization of this resource. effective management of groundwater aquifers is heavily influenced by the accurate estimation of recharge. however, the recharge is one of the water cycle components most difficult to quantify accurately as it varies significantly in temporal and spatial dimensions [3-10]. there is no technique for direct measurement of recharge due to the lack of universal standard methods [11]. nevertheless, numerous methods, ranging widely in complexity and cost, have been used to estimate recharge [6, 12]. these methods involved a variety of approaches, including soil moisture budgeting, well hydrograph analysis, numerical modeling and a catchment water balance [13]. in this study, groundwater recharge estimates based on the water balance model is assessed. this study is conducted in gumselasa catchment in the tigray region, which is the northern most region of ethiopia. with a total land area of 8 million ha, tigray is one of the most degraded and drought prone regions of ethiopia [14]. the frequent dry spells and droughts exacerbate the incidence of crop failure and hence food insecurity and poverty. gumselassa catchment includes a small dam called gumselassa dam. the dam was constructed in 1995 by cosaert (commission for sustainable agriculture and environmental rehabilitation in tigray) for the purpose of irrigation and was designed to irrigate 120 ha of land [15]. even though the dam was constructed twenty three years ago, the water balance which takes into account the whole catchment of gumselasa has not yet been studied. the available outflow, inflow and surplus waters in the effective watershed, reservoir and command area are not determined so far. this research, which makes its objective on determination of recharge in whole catchment of gumselasa, was conducted to provide quantitative information about the water budget components in the area. 1.2. description of the study area 1.2.1. location gumselasa catchment is located bounded between 556000 – 564000m e and 1458000 –1467000m n, having an area of 28.1 sq. kms (fig. 1). 1.2.2. physiography and drainage geomorphologically the study area is dominantly flat to gentle sloping area interrupted in some parts with small dome undulating topography having an orientation of n-s and constituted by dolerite. chain of mountains made the eastern boundary of the study area. the altitude of the catchment ranges from 2218 m above mean sea level on the top of the mountain to 2100m above sea level at the reservoir point. the catchment drains by two major perennial streams: asegeda and mehombiya rivers (fig. 2). asegeda river rises from the eastern mountainous area whereas the mehombiya river from the southeast mountainous area. both of them flow to the west, and joined and form one big river. there are also other intermittent streams in the catchment. generally, the catchment has a dendritic drainage pattern. as it was mentioned above the catchment area comprises a small dam called gumselasa dam (fig. 2). the dam axis has a length of 400 m and a height of 13.5m with a water holding capacity of 1.92 million cubic meters and was designed to irrigate 120 ha of land [15]. currently the available water in the dam is 0.194 million cubic meters. 1.2.3. soil and land use to investigate soil types of the area, seven pits were drilled in different parts of the catchment, and representative soil samples were taken from each of them for textural study at laboratory. the result indicates that the catchment is found dominated by two types of soil: clay and sandy clay loam. the clay is found covering part of the effective watershed, all the water contributing areas and command area whereas the sandy clay loam is found covering only parts of the effective watershed area on the east and northeast parts of the catchment. water contributing areas are areas that are found adjacent to the command area that directly contributes water to the command area but not to the dam. the different land use patterns of the catchment were identified during the fieldwork. accordingly, cultivated land, grassland, and chain of mountains in the eastern and northeastern, which are mainly bare land, are the major land use patterns of the catchment. cultivated land constitutes the major portion of the effective watershed area, the whole water contributing areas and the command area. grassland is found just occupying a small area in the effective watershed parts of the catchment. the major crops cultivated in the area are cereal crops such as wheat, teff, sorghum, maize and barely. 2. methodology in this study the groundwater recharge of the whole catchment is estimated using water balance model. asian review of environmental and earth sciences, 2018, 5(1): 34-46 36 2.1. water balance model the water balance model equation for any natural area (such as a river basin) or water body indicates the relative values of inflow, outflow and change in water storage for the area or water body. in general, the inflow part of the water balance equation comprises precipitation (p) as rainfall and snow actually received at the ground surface, and surface and subsurface water inflow into the basin or water body from outside (qsi and qux). figure-1. location map of the study area (northern ethiopia bounded in the northwest by sudan, north and northeast by eritrea, and east by djibouti and somalia: the rift valley escarpment is part of the eastern escarpment of the east african rift system). source: after nyssen, et al. [16] figure-2. gumselassa reservoir with its components (effective watershed areas, dam, water contributing areas and command area. 1 is asegeda river and 2 is mehombiya river). source: modified after michiele [17] asian review of environmental and earth sciences, 2018, 5(1): 34-46 37 the outflow part of the equation includes evaporation from the surface of the water body (e) and surface and subsurface outflow from the basin or water body (qso and qup). when the inflow exceeds the outflow, the total water storage in the body (δs) increases; whereas when an inflow less than the outflow results in decreased storage. consequently the water balance for any water body and any time interval in its general form may be represented by the following equation [18]: p + qsi + qux e qso qup  δs = 0 (1) for application to a variety of water-balance computations equation 1 may be simplified or made more complex, depending on the available initial data, the purpose of the computation, the type of body (river basin or artificially separated administrative district, lake or reservoir, etc.), and the dimensions of the water body, its hydrographic and hydrologic features, the duration of the balance time interval, and the phase of the hydrological regime (flood, low flow) for which the water balance is computed. 2.2. data collection boundary delineation of the effective watershed, reservoir, command area and adjacent water contributing areas to the command area was done using garmin gps and topographic map with a scale of 1:50,000 as a base map. maps were prepared using the readings and the topographic map as a base map. in order to determine the basic hydrologic parameters, meteorological data were collected from two meteorological stations. due to lack of sufficient meteorological data in the study area besides to the data that were collected from adigudem meteorological station, which is located in the study area, data from a nearby mekelle airport meteorological station was used for this study. both of them are owned by the national meteorological service agency. for the analysis, rainfall data was collected from adigudem meteorological station. the remaining climatic data such as temperature, wind speed, humidity and sunshine hours were taken from mekelle airport meteorological station. available relevant reports and thematic maps were also collected from different sources. for computation of the actual evapotranspiration, the dominant soil types and the respective root depth were determined for the different parts of the catchment. seven soil samples were collected from the different parts of the catchment to identify the soil types, the field capacity, permanent welting point and available water capacity in the measured root depths. soil samples were analyzed for grain size, field capacity and permanent wilting point in mekelle university, land resources and environmental protection department soil laboratory. seepage flow from the dam was measured daily for three consecutive months by installing rectangular weir at downstream of the dam at the place where the seepage water is concentrated (fig. 3). the kinds vatercarter rectangular weir equation [19] empirical formula was used to compute the daily flow. √ (2) where q is discharge (l3/t), ce is discharge coefficient, g is acceleration of gravity (l/t2), b is notch width (l), h is head (l), and kb and kh account for effects of viscosity and surface tension (l). figure-3. rectangular weir for seepage measurement: installed rectangular weir for measuring the seepage at the downstream side the dam. source: michiele [17] 2.3. data processing the rainfall coefficient method [20] was used to determine the monthly distribution of rainfall in the study area and then to distinguish between rainy months and dry months. this method involved the calculation of "rainfall coefficient" for each month at the station, the coefficient being the ratio between the mean monthly rainfall and one-twelfth of the annual mean (the latter referred to as "rainfall module"). in the catchment, pan evaporation data were not available. because of this, the penman method [21] was used to calculate the evaporation from the reservoir. the penman formula for open water evaporation is: ( ) ( ) where e0 is open water evaporation in mm/day; h is the available heat; is a weighting factor (a function of temperature); and, ea is to be determined empirically in (mm/day). the formula requires values of h and ea as well as for its application in the open water evaporation from open water bodies such as the gumselasa reservoir. asian review of environmental and earth sciences, 2018, 5(1): 34-46 38 h is calculated from incoming (ri) and outgoing (ro) radiation determined from sun shine records, temperature and relative humidity using where r is the albedo and equals 0.05 for water. potential evapotranspiration of the catchment was determined by both penman modified and thornthwaite methods. the penman equation, which was later modified by maff [21] and called modified penman equation, is given by: 1            att eh pet (5) where: pet is potential evapotranspiration (mm/day); δ is slope of saturated vapor pressure vs temperature curve (mmhg/oc); γ is the hydrometric constant (mmhg/oc); oit rrrh  )1(75.0 ;          n n frrr aai 75.01 ; ri is incoming radiation; r = 0.25 since the reflective coefficient for incident radiation, the albedo, from a short grassed surface is 0.25;       n n fa =        n n 62.016.0 for latitudes south of 54-20n [22];   )/83.017.0(075.047.04 0 nnetr a  ;  t4 is theoretical black body radiation at t (mean air temperature in oc); ro is out going radiation;  = stefan-boltzmann constant (5.67*10-8 wm-2k-4); t = mean monthly temperature (oc); )( 100 135.0 2 asat ee u e        ;( the extra subscript t signifies inclusion of transpiration effects). u2= wind speed at 2 m height (mile/hr) (1mile = 1.609km); n= maximum possible sunshine hours (hr); n = sunshine hours (hr); es= saturated vapor pressure (mm hg); ea = actual vapor pressure (mm hg) is obtained from the formula: rh=es /ea *100 …………………………..………………………. (6) where: rh is relative humidity in percent. ra, n,  t4,es and δ/γ were obtained from standard metrological tables, which can be readily found elsewhere in hydrology literature. the thornthwaite method [18] uses air temperature as an index of the energy available for evapotranspiration, assuming that air temperature is correlated with the integrated effects of net radiation and other controls of evapotranspiration and that the available energy is shared in fixed proportion between heating the atmosphere and evapotranspiration. the thornthwaite empirical equation is: * + (7) where, pet is potential evapotranspiration (mm/month); tn is mean monthly air temperature (°c); n = 1, 2, 3 ,………., 12 is the number of considered months; j is annual heat index and it is given by the equation; ∑ (8) j is monthly heat index and it is expressed as: ( ) (9) a = 0.49239+0.01792j-0.0000771j2+ 0.000000675j3 (10) nm is daylight correction factor for potential evapotranspiration (latitude dependent). actual evapotranspiration data was not available in the stations employed in this study. due to almost complete lack of field instruments such as lysimeters, the thornthwaite water balance model [22] was used to estimate the actual evapotranspiration of the study area. the required parameters to determine actual evapotranspiration using this model are: mean monthly precipitation, mean monthly potential evapotranspiration, water holding capacity of the dominant soil type and monthly soil moisture storage. the total mean actual evapotranspiration that occurs in the catchment was determined by arithmetic mean of the annual actual evapotranspiration from each area that is covered by specific soil type weighted by their area coverage. ∑ (11) where asian review of environmental and earth sciences, 2018, 5(1): 34-46 39 aett is total actual evapotranspiration; aeti is mean annual actual evapotranspiration from each area that is covered by specific soil type; ai is area of each specific soil type; and, a is total catchment area. the volume of runoff from the effective watershed area, water contributing areas, and command area were computed by using the runoff coefficient method [23] which employed the following formula. where q is runoff, m³: k is a constant also called runoff coefficient depends up on the imperviousness of the drainage area: p is precipitation (mm): and, a is area of the basin (m²). the runoff coefficient (k) in the runoff coefficient method was determined based on the land use, soil type (hydrological soil groups) and slope. the four hydrologic soil groups (hsgs) that described by suresh [24] was used in the computation of runoff. water balance was done for the effective watershed area of the dam, for the dam, for the areas that contributing water for the command area and for the command area itself. the water balance of the effective watershed area of the dam, the dam, and the areas that contributing water for the command were conducted to quantify the different input of the hydrological parameters of the water balance to the command area. various assumptions have been made to derive the water balance equation for the studied area from the general equation, which is eq. 1, and these are summarized below: 1. since the computations are made on annual basis, net change of soil moisture and groundwater storage is assumed to be zero. 2. subsurface water exchange with neighboring basins is assumed to be zero. 3. assuming no artificial diversion from other basins. thus the water balance equation for the study area is written as follows, which is p et q i = 0 (13) where p = precipitation; et = evapotranspiration; i = infiltration; and, q = runoff from the catchment. in the case of the reservoir, evapotranspiration is replaced by evaporation. 3. results and discussions 3.1. hydrology the hydrology of the catchment has been examined in terms of land use, soil and climatic parameters of the catchment such as rainfall, temperature, wind speed, evapotranspiration and runoff. detailed sections on climatic parameters follow. 3.1.1. rainfall mean annual rainfall a twenty years rainfall data (1992-2011) was collected for this study and the mean is tabulated and presented in table 1. accordingly, the mean annual rainfall of the study area is 485.89 mm. the mean monthly rainfall averaged over the twenty years period of records for the adigudem station is shown in figure 4. figure-4. mean monthly rainfall at adigudem station. the rainfall is averaged over the twenty years (1992-2011) period of records at this station. table-1. mean monthly rainfall at adigudem station (in mm). month jan feb mar apr may jun jul aug sept oct nov dec mean annual mmrf 1.25 1.25 9.20 21.03 18.11 19.65 155.46 212.1 38.50 5.01 3.05 1.30 485.89 where mmrf is mean monthly rainfall. seasonality of rainfall the seasonality of the study area was examined based on rainfall coefficient methods [20]. the guideline is given in table 2 below. as depicted in table 3, the catchment is characterized by one rainy season during the year, i.e., at this station rainy months are not separated into more than one group of rainy months by dry months. there are two dry seasons during the year. the rainy season in total have three months: july, august, and september. the rains in september are small rain and accounts 7.92% of the average annual rainfall of the catchment. big rains with a very high concentration occur in july and august, and these accounts for 75.64% of the average annual rainfall of the watershed. the first dry season starts in january and ends in june. the second one starts in october and ends in december. the amount of rainfall that occurs during the nine months of dry seasons in total accounts for asian review of environmental and earth sciences, 2018, 5(1): 34-46 40 16.43% of the average annual rainfall of the watershed. the study area has not experienced moderate and high concentration of rainfall, which is essential for direct recharge of groundwater. table-2. rainfall coefficient values and their classification. s.n months rainfall coefficient values (rc) 1 dry month less than 0.6 2 rainy 0.6and above 3 small rain 0.6-0.9 4 big rain 1 and above 4.1 moderate concentration 1-1.9 4.2 high concentration 2-2.9 4.3 very high concentration 3 and above source: daniel [20]. table-3. rainfall coefficient at the adigudem station. month jan feb mar apr may jun jul aug sept oct nov dec mmrf 1.25 1.25 9.20 21.03 18.11 19.65 155.46 212.08 38.50 5.01 3.05 1.30 rc 0.03 0.03 0.23 0.52 0.46 0.48 3.84 5.25 0.95 0.12 0.07 0.03 season dry dry dry dry dry dry rainy rainy rainy dry dry dry amount big big small concentration very high very high where, mmrf is mean monthly rainfall (mm); and, rc is rainfall coefficient values. 3.1.2. temperature for temperature analysis of the area, a twenty-year (1992-2011) maximum temperature and minimum temperature data were taken and analyzed. the mean annual minimum temperature of the study area is 11.73 ºc and the mean annual maximum temperature is 24.21 ºc. the mean annual air temperature of the area is 17.97 ºc (table 4). the mean monthly maximum and minimum temperature are observed in june and december, which are 27.01°c and 9.39 °c, respectively. as it is shown in the above table 4, the minimum air temperature is 15.94 ºc in december and the maximum air temperature is 20.39 ºc in may. the annual range of temperature is 4.45 ºc. table-4. mean monthly temperature at mekelle airport meteorological station. month jan feb mar apr may jun jul aug sep oct nov dec ma mmmxt (ºc) 22.97 24.39 25.13 25.79 26.94 27.01 23.31 22.36 24.25 23.62 22.45 22.26 mmmnt (ºc) 9.39 10.38 11.86 13.29 13.85 13.53 13.21 13.05 11.19 11.06 10.35 9.62 mmt (ºc) 16.18 17.39 18.49 19.54 20.39 20.27 18.26 17.71 17.72 17.34 16.40 15.94 17.97 where mmmxt is mean monthly maximum temperature; mmmnt is mean monthly minimum temperature; mmt is mean monthly air temperature; and, ma is mean annual air temperature. 3.1.3. wind speed for the wind speed analysis of the area, eleven years (1995 to 2011) data records were used. the mean monthly values were computed and are given in the table 5 below. the maximum and minimum wind speed value is obtained in february (4.23 m/s) and in august (1.71 m/s), respectively. in general, the highest and lowest wind speed values are found in the dry and rainy month, respectively. 3.1.4. sunshine hours for the analysis of solar radiation of the area, the data that was recorded from 1991 to 2011 were utilized. the mean monthly sunshine hours of the area are given in table 5 below. the maximum sunshine hour is recorded in december (9.87 hours) whereas the minimum one is in august (5.12 hours). generally, the maximum sunshine hours are found in dry months whereas the minimum are in very highly rainy months. 3.1.5. humidity for this analysis, the data that was recorded from 1991 to 2011 were utilized. the mean monthly values were computed and are given in the table 5 below. the maximum and minimum relative humidity values are found in august (74.23 %) and may (37.55 %), respectively. in general, the highest humidity values are found in the rainy months whereas the lowest values are in dry months. table-5. mean monthly wind speed, relative humidity and sunshine hours at mekelle airport meteorological station. months jan feb mar apr may jun jul aug sep oct nov dec rh (%) 46.47 41.09 40.85 40.71 37.55 40.20 69 74.23 50.55 43.15 45.05 44.25 n (hr/d) 9.60 9.74 9.03 8.94 9.62 7.44 5.13 5.12 7.70 9.49 9.85 9.87 u (m/s) 3.46 4.23 4.13 4 2.95 2.14 1.9 1.71 1.78 3.06 3.64 3.76 where rh = relative humidity in percentage (%); n = sun shine hours per day; and, u = wind speed in meter per second. 3.1.6. evaporation from the reservoir the monthly water loss from gumselassa reservoir due to evaporation was calculated by using the penman formula, eq. (3). the result shows that the total annual water loss by evaporation is 1263.27 mm or 0.505 million cubic meters (table 6). the highest value of evaporation was in month may in which the temperature is also high. the table below shows the total mean annual evaporation loss calculated using penman formula. asian review of environmental and earth sciences, 2018, 5(1): 34-46 41 table-6. evaporation from gumselassa dam reservoir. month jan feb mar apr may jun jul aug sep oct nov dec annual h 3.64 4.35 4.83 5.2 5.36 4.57 4.12 4.24 4.66 4.53 3.88 4.43 ea 1.38 1.65 1.77 1.89 2.10 1.99 0.89 0.71 1.37 1.55 1.44 1.44 e 2.83 3.42 3.82 4.15 4.78 3.78 3.05 3.05 3.55 3.51 3.02 2.72 eo 87.73 95.76 118.42 124.5 143.4 117.18 91.5 94.55 106.5 108.81 90.6 84.32 1, 263.27 where e is evaporation in mm/day, and eo is evaporation in mm/month. 3.1.7. evapotranspiration in this study, an attempt was made to estimate both potential evapotranspiration and actual evapotranspiration for the catchment. potential evapotranspiration both penman combination and thornthwaite methods were used to compute the potential evapotranspiration of the gumselassa catchment. according to thornthwaite method, the computed mean annual potential evapotranspiration is 805.83 mm (table 7). using penman method the potential evapotranspiration for the catchment was computed and the result is given in the table 8. accordingly, the mean annual potential evapotranspiration for the gumselassa catchment is 1,144.29 mm. preference to the value determined by penman method is given due to the number of parameters that are involved in the computation of the potential evapotranspiration. table-7. potential evapotranspiration using thornthwaite method. month jan feb mar apr may jun jul aug sep oct nov dec annual mmt (°c) 16.18 17.39 18.49 19.54 20.39 20.27 18.26 17.71 17.72 17.34 16.4 15.94 17.97 im 5.92 6.60 7.24 7.87 8.39 8.32 7.11 6.79 6.79 6.57 6.04 5.79 i=83.34 nm 0.94 0.97 1 1.04 1.06 1.08 1.07 1.05 1.07 0.98 0.95 0.93 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 where mmt is mean monthly air temperature; im is monthly heat index; nm is latitudinal correction factor for 10º n; and, pet is corrected potential evapotranspiration in (mm). table-8. potential evapotranspiration using penman method. month jan feb mar apr may jun jul aug sep oct nov dec mean annual t( co) 16.18 17.39 18.49 19.54 20.39 20.27 18.26 17.71 17.72 17.34 16.40 15.94 rh (%) 46.47 41.09 40.85 40.71 37.55 40.19 69.00 74.2 50.55 43.15 45.05 44.25 es(mmhg) 13.73 14.73 15.81 16.95 18.16 18.16 15.81 15.27 15.27 14.73 13.98 13.73 ea(mmhg) 6.38 6.05 6.48 6.90 6.82 7.27 10.91 11.33 7.72 6.36 6.29 6.08 u (m/s) 3.46 4.23 4.13 4 2.95 2.14 1.9 1.71 1.78 3.06 3.64 3.76 n(hr/d) 9.6 9.74 9.03 8.94 9.62 7.44 5.13 5.12 7.7 9.49 9.85 9.87 n (hr/d) 11.3 11.6 12.00 12.50 12.80 13.00 12.90 12.60 12.20 11.80 11.40 11.20 n/n 0.85 0.84 0.75 0.72 0.75 0.57 0.39 0.41 0.63 0.80 0.86 0.88 fa(n/n) 0.69 0.68 0.63 0.61 0.63 0.51 0.40 0.41 0.55 0.66 0.69 0.71 ra (mm/d) 11.80 13.15 14.4 15.20 15.35 15.30 15.30 15.20 14.60 13.55 12.20 11.45 σt4 a (min) 14.1 14.3 14.5 14.7 14.9 14.9 14.5 14.4 14.4 14.3 14.2 14.1 ro (mm/d) 3.46 3.54 3.21 3.08 3.24 2.57 1.59 1.59 2.61 3.35 3.54 3.62 1.80 1.91 2.03 2.16 2.32 2.27 2.03 1.97 1.97 1.91 1.83 1.80 ri(1-r) 6.08 6.71 6.75 6.91 7.19 5.89 4.61 4.72 6.03 6.66 6.34 6.06 ht (mm/d) 2.62 3.71 3.54 3.83 3.95 3.32 3.02 3.13 3.42 3.31 2.80 2.44 eat (mm/d) 2.66 3.17 3.14 3.66 4.09 3.89 1.75 1.40 2.69 3.02 2.79 2.78 pet (mm/d) 2.63 3.52 3.49 3.78 3.99 3.49 2.60 2.55 3.17 3.21 2.79 2.56 pet(mm/m) 81.53 98.56 108.19 113.4 119.7 108.19 78 79.05 95.1 99.51 83.7 79.36 1,144.29 actual evapotranspiration actual evapotranspiration was estimated for the dominant soil types and the respective root depth for the effective watershed, water contributing areas to the command area, and the command area of the study area, respectively. for the effective watershed, water contributing areas and the command area, these results are summarized and are given in tables 10 – 14 below. for computation of the actual evapotranspiration the soil result of the areas for field capacity, permanent welting point, root depth and available water capacity are given in table 9 below. table-9. result of soils for field capacity, permanent welting point (pwp) and available water capacity (awc). location field capacity (gm/gm) or % pwp (gm/gm) or % root depth (m) awc wca 1 32.20 21.62 0.75 79.31 uca2 32.88 23.76 0.8 72.98 lca3 29.13 19.12 0.5 50.02 ews4 19.71 11.14 0.6 51.37 ews5 21.86 13.18 0.7 60.77 ews6 29.41 20.49 0.6 53.54 wca 2 25.13 8.83 0.6 97.80 where wca = water contributing area; ews = effective watershed; uca = upper command area; and, lca = lower command area. asian review of environmental and earth sciences, 2018, 5(1): 34-46 42 table-10. average monthly water balance of gumselassa command area for a soil with an average available water capacity of 61.5 mm. the soil is clay with an average root depth of 0.65 m. all the values are in mm. month jan feb mar apr may jun jul aug sep oct nov dec annual p 1.25 1.25 9.2 21.03 18.11 19.65 155.46 212.08 38.5 5.01 3.05 1.3 485.89 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 p-pet -49.63 -58.7 -59.99 -58.63 -69.7 -68.84 83.11 114.97 -29.96 -55.24 -49.66 -47.67 apwl -232.16 -290.9 -350.85 -409.48 -479.18 -548.02 -29.96 -85.2 -134.9 -182.53 sm 1.22 0.45 0.17 0.06 0.02 0.006 61.50 61.50 37.10 14.61 6.32 2.83 ∆sm -1.60 -0.77 -0.29 -0.10 -0.04 -0.01 61.49 0 -24.4 -22.49 -8.29 -3.49 aet 2.85 2.01 9.49 21.13 18.15 19.66 72.35 67.11 62.90 27.5 11.34 4.79 319.3 table-11. average monthly water balance of gumselassa effective watershed area for a soil with available water capacity of 56.07 mm. the soil is clay with an average root depth of 0.65 m. all the values are in mm. month jan feb mar apr may jun jul aug sep oct nov dec annual p 1.25 1.25 9.2 21.03 18.11 19.65 155.46 212.08 38.5 5.01 3.05 1.3 485.89 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 p-pet -49.63 -58.7 -59.99 -58.63 -69.7 -68.84 83.11 114.97 -29.96 -55.24 -49.66 -47.67 apwl -232.16 -290.9 -350.85 -409.48 -479.18 -548.02 -29.96 -85.2 -134.9 -182.53 sm 0.52 0.16 0.05 0.02 0.004 0.001 52.46 52.46 28.90 9.63 3.58 1.39 ∆sm -0.871 -0.356 -0.112 -0.033 -0.011 -0.003 52.456 0 -23.56 -19.272 -6.044 -2.197 aet 2.12 1.61 9.31 21.06 18.12 19.65 72.35 67.11 62.06 24.28 9.09 3.50 310.27 table-12. average monthly water balance of gumselassa effective watershed area for a soil with an available water capacity of 53.54 mm. the soil is sandy clay loam with an average root depth of 0.6 m. all the values are in mm. month jan feb mar apr may jun jul aug sep oct nov dec annual p 1.25 1.25 9.2 21.03 18.11 19.65 155.46 212.08 38.5 5.01 3.05 1.3 485.89 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 p-pet -49.63 -58.7 -59.99 -58.63 -69.7 -68.84 83.11 114.97 -29.96 -55.24 -49.66 -47.67 apwl -232.16 -290.9 -350.85 -409.48 -479.18 -548.02 -29.96 -85.2 -134.9 -182.53 sm 1.15 0.42 0.15 0.056 0.02 0.01 60.77 60.77 36.42 14.18 6.07 2.69 ∆sm -1.54 -0.73 -0.27 -0.1 -0.04 -0.01 60.76 0 -24.34 -22.25 -8.11 -3.38 aet 2.79 1.98 9.47 21.13 18.15 19.66 72.35 67.11 62.84 27.26 11.16 4.68 318.57 asian review of environmental and earth sciences, 2018, 5(1): 34-46 43 table-13. average monthly water balance at gumselassa water contributing area 1 for a soil with available water capacity of 79.31 mm. the soil is clay with an average root depth of 0.75 m. all the values are in mm. month jan feb mar apr may jun jul aug sep oct nov dec annual p 1.25 1.25 9.2 21.03 18.11 19.65 155.46 212.08 38.5 5.01 3.05 1.3 485.89 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 p-pet -49.63 -58.7 -59.99 -58.63 -69.7 -68.84 83.11 114.97 -29.96 -55.24 -49.66 -47.67 apwl -232.16 -290.9 -350.85 -409.48 -479.18 -548.02 -29.96 -85.2 -134.9 -182.53 sm 3.91 1.83 0.84 0.39 0.16 0.07 79.31 79.31 53.79 26.29 13.81 7.44 ∆sm -3.53 -2.09 -0.99 -0.45 -0.23 -0.09 79.24 0 -25.52 -27.5 -12.48 -6.37 aet 4.78 3.34 10.19 21.48 18.34 19.74 72.35 67.11 64.02 32.51 15.52 7.67 337.06 table-14. average monthly water balance at gumselassa water contributing area 2 for a soil with available water capacity of 97.8mm. the soil is clay with an average root depth of 0.6 m. all the values are in mm. month jan feb mar apr may jun jul aug sep oct nov dec annual p 1.25 1.25 9.2 21.03 18.11 19.65 155.46 212.08 38.5 5.01 3.05 1.3 485.89 pet 50.88 59.95 69.19 79.66 87.81 88.49 72.35 67.11 68.46 60.25 52.71 48.97 805.83 p-pet -49.63 -58.7 -59.99 -58.63 -69.7 -68.84 83.11 114.97 -29.96 -55.24 -49.66 -47.67 apwl -232.16 -290.9 -350.85 -409.48 -479.18 -548.02 -29.96 -85.2 -134.9 -182.53 sm 8.69 4.71 2.52 1.36 0.66 0.32 97.80 97.80 71.56 40.23 23.97 14.58 ∆sm -5.89 -3.98 -2.19 -1.15 -0.71 -0.34 97.48 0 -26.24 -31.33 -16.26 -9.39 aet 7.14 5.23 11.39 22.18 18.82 19.99 72.35 67.11 64.74 36.34 19.31 10.69 355.29 where p = mean monthly precipitation; pet = corrected potential evapotranspiration; p pet = is difference by subtraction; apwl = accumulated potential water loss; sm = soil moisture; δsm = change in soil moisture during the month; aet = actual evapotranspiration. . asian review of environmental and earth sciences, 2018, 5(1): 34-46 44 © 2018 by the authors; licensee asian online journal publishing group the summery result of actual evapotranspiration (table 15) shows the maximum is in the southern water contributing area to the command area which has clay soil. table-15. summary of the computed values of actual evapotranspiration. area actual evapotranspiration (mm) effective watershed with sandy clay loam soil (ewsscl) 318.57 effective watershed with clay soil (ewsc) 310.27 water contributing area – 1 (wca 1) 337.06 command area (ca) 319.3 water contributing area – 2 (wca 2) 355.29 3.1.8. surface runoff in this study, the mean annual runoff for the effective watershed area (upper catchment area), water contributing areas and the command area was determined using runoff coefficient method, eq. (12). the computation of runoff was done by classifying the catchment into different land use, slope class and the hydrologic soil groups, and the result is summarized and given in table 16 below. table-16. surface runoff from the different parts of the catchment. catchments land use type soil type hydrologic group of soil slope runoff coefficient area (km2) runoff (m3) ewsscl cultivated land fine sandy clay loam c 0 2 0.14 17.16 1.167x106 ewsc cultivated land clay d 0 2 0.18 4.98 0.44x106 ca cultivated land clay d 0 2 0.18 1 8.75x104 wca 2 cultivated land clay d 0 2 0.18 3.99 3.49x105 wca 1 cultivated land clay d 0 2 0.18 0.55 0.048 x 106 3.2. water balance water balance for the effective watershed with sandy loam soil precipitation is the only input component to the effective watershed area with sandy clay loam soil, whereas actual evapotranspiration, runoff and infiltration are on the output side. from the budget equation, the amount of water that percolates into the ground in the upper catchment as a groundwater accretion has been calculated as follows. as = area of the upper catchment = 17.16 sq. km; aet = 54.683*105m3; p = 83.4*105m3; and, q = 11.67*105m3. from equation 13, i = p aet q = 1.705* 106 m3 water balance for effective watershed with clay soil precipitation is the only input component to the effective watershed area with clay soil, whereas actual evapotranspiration, runoff and infiltration are on the outputs from the area. from the budget equation, eq. 13, the amount of water that percolates into the ground in the upper catchment as a groundwater accretion has been calculated as follows. as = area of the upper catchment = 4.98 sq. km; aet = 1.55*106 m3; p = 2.42*106 m3; and, q = 0.44*106 m3. using equation 13 i = p aet – q = 0.43* 106 m3 water balance for the reservoir precipitation and runoff from effective watershed with sandy loam and clay soil are the input components to the reservoir whereas evaporation, infiltration at the reservoir site or bed, and the discharges to the command area constitute the output components. from the budget equation, the amount of water that percolates into the ground at the reservoir site as a groundwater accretion has been calculated as follows. as = area of the reservoir = 0.4 sq. km; e = evaporation from the reservoir = 0.505 x 106 m3; p = 0.194 x 106 m3; qi = 1.607*106 m3; (sum of input discharges from effective watershed with clay and sandy loam); qd= 0.203x 06 m3. (discharge from the reservoir to the command area, which is measured at the field); and, qs = 0.35 x 106 m3; (seepage discharge) i = p + qi e– qd qs i = [(0.194 + 1.607 – 0.505 0.203 0.35)] x 106 m3 = 0.743 x 106 m3 water balance for water contributing area 1 in the water contributing area 1 to the command area the only input is precipitation and the output hydrologic components from the area are actual evapotranspiration, runoff and infiltration. therefore, from the budget equation, the amount of water that percolates into the ground at the northern water contributing area as a groundwater accretion has been calculated as follows. as = 0.55 sq. km; aet = 0.19 x 106 m3; p = 0.267 x 106 m3; and, q = 0.048x 106 m3. using equation 13 i = p et – q = 0.029 x 106 m3 asian review of environmental and earth sciences, 2018, 5(1): 34-46 45 © 2018 by the authors; licensee asian online journal publishing group water balance for water contributing area 2 the only input for water contributing area 2 for the command area is precipitation, and actual evapotranspiration, runoff and infiltration are the outputs from the area. therefore, from the budget equation, the amount of water that percolates into the ground at the southern water contributing area as a groundwater accretion has calculated as follows. as = 3.99 sq. km; aet =1.42 x 106 m3; p = 1.94 x 106 m3; and, q = 0.349 x 106 m3. using equation 13 i = p et – q = 0.171* 106 m3 water balance for the command area precipitation, the discharge from the reservoir, seepage and the surface runoff from the water contributing areas are the input components to the command area whereas evapotranspiration, runoff from the command area, discharge to water supply and infiltration into the groundwater at the command area constitutes the output components. from the budget equation, the amount of water that percolates into the ground in the command area as a groundwater accretion has calculated as follows. as = area of the command area = 1 sq. km; aet = 0.32 x 106 m3; p = 0.486 x 106 m3; qs = 0.35 x 106 m3; (seepage discharge); qd= 0.203 x 106m3(discharge from the reservoir to the command area, which is measured at the field); qc = surface runoff from the surrounding command areas into the command area = 0.397 x 106 m3; q = runoff from the command area = 8.75 x 104 m3; and, qw = 0.042 x 106m3 (borehole discharge: total volume in year for water supply to adigudem town, which is a town nearby to the reservoir , as computed from the gage). using equation 13 i = p + qd + qs + qcet – q – qw = 0.987 x 106 m3 recharge in catchment the total amount of water which is actually available to recharge the groundwater circulation within the catchment is 4.065 million cubic meters. this amount of recharge is mainly due to the availability of the dam in the catchment. any application of water for irrigation from the reservoir should take into account this readily available water to avoid unnecessary increment in the level of groundwater that can cause soil problems in the catchment. 4. conclusions the gumselasa catchment is semi-arid area where the 75.64 % of the mean annual rainfall occurred in the two months of the rainy season of the year with very high concentration. the rainy season has a total of three months. the recharge to the groundwater in the catchment was about 29.77% of the mean annual rainfall of the catchment, and any application of water for irrigation from the reservoir should take into account this readily available water. references [1] h. bouwer, groundwater hydrology. new york: mcgrawhill book company, 1978. [2] r. s. seyed, y. ismail, m. saari, and s. saghravani, "estimating groundwater recharge using empirical method: a case study in the tropical zone," sains malaysiana, vol. 42, pp. 553-560, 2013. [3] a. o’grady, j. carter, and k. holland, "review of australian groundwater discharge studies of terrestrial systems. csiro: water for a healthy country national research flagship, national water commission, australia, 2010," p. 60, 2017. [4] r. dhungel and f. fiedler, "water balance to recharge calculation: implications for watershed management using systems dynamics approach," hydrology, vol. 3, p. 13, 2016.available at: https://doi.org/10.3390/hydrology3010013. [5] b. r. scanlon, k. e. keese, a. l. flint, l. e. flint, c. b. gaye, w. m. edmunds, and i. simmers, "global synthesis of groundwater recharge in semiarid and arid regions," hydrological processes, vol. 20, pp. 3335–3370, 2006.available at: https://doi.org/10.1002/hyp.6335. [6] b. r. scanlon, r. w. healy, and p. g. cook, "choosing appropriate techniques for quantifying groundwater recharge," hydrogeology journal, vol. 10, pp. 18-39, 2002.available at: https://doi.org/10.1007/s10040-001-0176-2. [7] y. xu and h. e. beekman, "groundwater recharge estimation in southern africa. unesco ihp series no. 64, unesco paris," p. 207, 2003. [8] p. mcmahon, l. plummer, j. böhlke, s. shapiro, and s. hinkle, "a comparison of recharge rates in aquifers of the united states based on groundwater-age data," hydrogeology journal, vol. 4, pp. 779-800, 2011.available at: https://doi.org/10.1007/s10040011-0722-5. [9] s. tyler, j. chapman, s. conrad, d. hammermeister, d. blout, j. miller, m. sully, and j. ginanni, "soil-water flux in the southern great basin, united states: temporal and spatial variations over the last 120,000 years," water resources research, vol. 32, pp. 1481-1499, 1996.available at: https://doi.org/10.1029/96wr00564. [10] d. m. wolock, estimated mean annual natural groundwater recharge in the conterminous united states. reston, va, usa: u.s. geological survey, 2003. [11] m. anderson and w. woessner, applied groundwater modeling. san diego: academic, 1992. [12] d. n. lerner, a. s. issar, and i. simmers, groundwater recharge: a guide to understanding and estimating natural recharge vol. 8. hannover: heise, 1990. [13] b. misstear, l. brown, and p. johnston, "estimation of groundwater recharge in a major sand and gravel aquifer in ireland using multiple approaches," hydrogeology journal, vol. 17, pp. 693-706, 2009.available at: https://doi.org/10.1007/s10040-008-0376-0. [14] y. eyasu, g. temesgen, g. e. tesfa-alem, m. atinkut, f. degol, h. solomon, h. abraham, v. s. frank, and w. flip, "spate irrigation systems in raya valley (ethiopia), spate irrigation network, overview paper no. 13," 2012. [15] commission for sustainable agriculture and environmental rehabilitation in tigray (cosaert), "preliminary assessment on the overall impact of dams, mekele, tigray, ethiopia," 2001. [16] j. nyssen, j. poesen, k. descheemaeker, n. haregeweyn, m. haile, j. moeyersons, a. frankl, g. govers, n. munro, and j. deckers, "effects of region-wide soil and water conservation in semi-arid areas: the case of northern ethiopia," journal of geomorphology, vol. 52, pp. 291-315, 2008.available at: https://doi.org/10.1127/0372-8854/2008/0052-0291. [17] g. michiele, "assessment of sources of salinity in gumselasa irrigation scheme, southern tigray, ethiopia," a thesis presented to the department of earth sciences, mekelle university, in partial fulfillment of the requirements for the degree of master of science (msc), 2014. asian review of environmental and earth sciences, 2018, 5(1): 34-46 46 © 2018 by the authors; licensee asian online journal publishing group [18] t. nata, t. shishay, and t. mekdes, "the water balance of may nugus catchment, tigray, northern ethiopia," international journal of earth sciences and engineering, vol. 3, pp. 609-625, 2010. [19] international organization of standards (iso), "iso 1438-1 water flow measurement in open channels using weirs and venturi flumes part 1: thin-plate weirs, iso,geneva, switzerland," 1980. [20] g. daniel, aspects of climate and water budget in ethiopia. addis ababa: addis ababa university press, 1974. [21] m. s. elizabeth, hydrology in practice, 3rd ed.: crc press, 1994. [22] l. b. leopold and t. dunne, water in environmental planning. san francisco: w. h. freeman and company, 1978. [23] s. k. garg, irrigation engineering and hydraulic structures. india: khanna publishers, 1987. [24] r. suresh, soil and water conservation engineering, 4th ed. new delhi: standard publishers distributors, 2002. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 2, 35-41, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 35 rural non-agricultural working force and levels of development in uttar pradesh: a regional analysis (india) shafiqullah 1* --sana asma 2 1 department of geography faculty of science, aligarh muslim university aligarh, india 2 research scholar (ugc-srf), department of geography faculty of science, aligarh muslim university aligarh, india abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 36 2. data and method ....................................................................................................................................................................... 37 3. conclusion .................................................................................................................................................................................. 40 references ...................................................................................................................................................................................... 40 the present paper investigate the trends of rural non-agricultural working force over the period of 1971 to 2011, the regional variations in the rural non-agricultural working force and the relationship between rural non-agricultural working force and levels of development among the districts of uttar pradesh. the regional variations in the distribution of workforce in rural non-agricultural sectors are quite notable. the general picture emerged that there is a gradual increase of main workforce in non-agricultural sector from north-western to south-eastern parts of uttar pradesh. the distribution of female main workforce in non-agricultural workforce depicts that there is a gradual decrease from west to southeast. the statistical analysis leads to conclusion that agriculture, population growth and health facilities are the chief determinants but the magnitudes of their effects are dissimilar. keywords: working force, agriculture, population growth, health facilities, magnitude, development. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(2): 35-41 36 1. introduction since the early 1970s attention has been paid to the significance of the non-agricultural sector in the rural indian economy. the census on occupational classification of workers [1] provided a far more detailed picture of the composition of the nonagricultural workers in rural areas. workers were classified into about one hundred occupational groups, along with their further subdivisions. the data allowed grouping of the rural workers in four classes: (a) workers engaged in producing goods and providing services to local population, (b) government instituted workers giving educational, medical, transportation and such like services to the people, (c) workers engaged in nonagricultural production and services oriented to non-local markets, and (d) adventurous workers, such as technical personnel, administrative staff and proprietors working on various development projects in rural areas. the economy of rural areas in india is predominantly based on agriculture and other activities related to agriculture sector. hence an overwhelming majority of rural population mainly depends on agriculture sector both for its employment and livelihood. at the same time various non-agricultural activities are also playing an important role in providing the opportunities of employment and incomes to the labourforce belonging to both farming and non-farming households. though, the nature of employment as available either in agricultural or non-agricultural activities is measured for a shorter duration. as per 2011 census, nearly one-fourth of the rural work force (main workers) was reported to be employed in non-agricultural pursuits. the non-agricultural activities include all economic activities other than crop production and allied agricultural activities such as animal husbandry, plantations, fishing, forestry, etc. rural non-agricultural economic activities consist of wide ranging various traditional and modern manufacturing industries, mining and quarrying, construction, trading, transport, storage and communication, hostelling and those rendering community and personal services. the non-agricultural work may often be undertaken as a secondary activity. this view of the rural populations exclusive dependence on agriculture has began to change in the past few years. the reflection in the shift of workforce from agriculture sector to non-agriculture sector has been well visualized in almost all the states in india. occupational diversification away from agriculture in favour of non-agriculture activities in the rural economy has generated a lot of interest among researchers. the issue is whether the declining share of agriculture in employment reflects maturing of positive growth forces in the economy or a result of adverse trends in the agrarian sector resulting in the growing inability of agriculture to further absorb the expanding labourforce. many studies make important contributions in the scrutiny of the nature of employment in the rural non-agricultural sector especially at the all-india level [2-6]. however, there are no such significant studies carried out for uttar pradesh (u.p.) in particular, which is the most populous state in the country. one sixth of the world’s population lives in india and one-sixth of india’s population lives in uttar pradesh. its share in total area of the country is 7.3 per cent. the predominance of rural population makes the state economy primarily agrarian. the state’s two thirds of the total workers are still engaged in agriculture and allied activities. the economic development and income of the people in the state depend largely on its agricultural base. however, the state has lately witnessed rapid industrialization after liberalization and globalization of the national economy. after consolidation of hilly districts and some plain areas into a separate state of uttarakhand, uttar pradesh now largely consists of fertile plain of ganga basin in part. at present it extends between 23 0 52' and 30° 24' n latitudes and 77 0 05' and 84° 38' e longitudes. the state shares international border with nepal and tibet in northeast, with the indian states of himachal pradesh in northwest, haryana, rajasthan and delhi in west and madhya pradesh and chattisgarh in south, and bihar and jharkhand in southwest (figure 1). fig-1. based on census of india, 2011 geographically, the location of uttar pradesh and its climate are conducive to earn livelihood from agriculture and diversification of its economy. the state is well known for success in the green revolution and for the highest production of food-grains and sugarcane in the country. however, the poverty is widespread in the state as it has the highest number of people below poverty line (about 32 per cent) as compared to the other states. it lags behind not asian review of environmental and earth sciences, 2015, 2(2): 35-41 37 only in economic progress but in terms of indicators of human development as well. the state has wide variations in the level of development, we can expect that factors driving non-agricultural workforce growth would also vary. it is likely that in the most developed western region, diversification of workforce away from agriculture would reflect the role of demand –pull factors generated by agricultural dynamism, while in the western, eastern and southern regions distress-push can play a role in increasing the volume of non-agricultural workforce. a study of rural nonagricultural workforce is crucial to an understanding of the regional pattern of diversification of rural economy. the magnitude and direction of shift from agriculture to non –agriculture is worth investigation and equally essential is to probe into the role of diverse factors in the process. in the light of the above facts, an attempt has been made to study the ‘rural non-agricultural working force and levels of development in uttar pradesh’ under three main sections. in the section i, we analyze the trends of rural non-agricultural working force over the period of 1971 to 2011. section ii explains the regional variations in the rural non-agricultural working force and the section iii finds out the relationship between rural non-agricultural working force and levels of development among the districts of uttar pradesh. 2. data and method the study is mainly based on the secondary sources of data obtained from the office of the registrar general of india and census commissioner, government of india, new delhi and the state planning institute, uttar pradesh, lucknow. the district has been taken as a unit of analysis due to: firstly, a fairly satisfactory data base is available at this level, secondly, it offers better facilities for formulation and implementation of plans as it has a definite administrative set up and fairly well defined geographical boundaries and finally, there is better possibility of coordination of micro-level planning at district level. for the identification of the levels of development and its correlates 39 variables have been selected (table 1). for this purpose the district wise value of each indicator is standardized with the help of ‘z’ score technique which is also known as 'zi' value or 'z' score. xij-xi zij = δxj where: zij= standardized value of the variable i in district j xij = actual value of variable i in district j xi = mean value of the variable i in all districts δ xj = standard deviation (δ) of variables in all districts after working out the 'z' score of all the indicators, composite score (c.s.) for each district has been calculated with the following algebraic expression: σzij cs = n where, c.s. is composite score, n refers to the number of variables, σzij indicate ‘z’ scores of all variables i in district j. the positive values relating to district's score show high level of development and negative values the low level of development. the correlation co-efficient between livestock and levels of development has been computed on the basis of the karl pearson's correlation co-efficient (r) method. 2.1. trends of rural non-agricultural working force uttar pradesh is predominantly an agricultural state. hence, a very low percentage of rural workforce is engaged in the non-agricultural sector. the share of rural workforce in non-agricultural sector has increased considerably over the decades at national level as well as state of uttar pradesh. table 2 reveals that the percentage of non-agricultural workforce improved from 12.30 per cent in 1971 to 24.33 per cent in 2001 and rose further to 27.85 per cent in 2011 in the state. at the national level, around one-seventh of the rural workforce was engaged in non-agricultural sector in 1971 which is increased by 25 per cent points in 2011 (39.32 per cent). during 1981-2011, the percentage of rural non-agricultural workforce has been gradually increased by nearly 20 per cent points both in the state and country. table-2.trends of rural non-agricultural workforce (main), uttar pradesh and india, 1971-2011 census year uttar pradesh india rural male female rural male female 1971 12.30 12.90 7.40 15.20 16.30 10.6 1981 13.68 14.11 9.55 19.02 20.84 12.73 1991 15.52 16.54 8.62 19.97 22.45 12.59 2001 24.33 24.63 22.63 29.37 31.66 22.95 2011 27.85 26.27 35.52 39.32 38.18 40.84 source: census of india, 1981, 1991, 2001 and 2011. when the share is computed for male and female workforce separately, it is found that the share in rural non-agricultural workforce has increased and the difference between sexes remained more or less similar. the percentage of male workforce in non-agricultural sector has increased during the period 1971-2011 from 16.3 to 38.18 per cent and from to 12.90 to 26.27 per cent respectively in india and uttar pradesh. the female workforce in uttar pradesh increased continuously from 7.40 per cent in 1971 to 35.52 per cent in 2011. india has also made a remarkable increase in female workforce during the same period. asian review of environmental and earth sciences, 2015, 2(2): 35-41 38 in the case of both male and female rural non-agricultural workforce the percentage was almost static during 1981-2011, but there has been a significant increase during the period 2001-2011 both in the country and state. however, the inequality in the percentage of male and female rural non-agricultural workforce remained more or less same during the reference period (table-2). fig-2. based on census of india, 1981, 1991 , 2001 and 2011. 2.2. rural non-agricultural workforce (main) the regional distribution of main non-agricultural workforce during the decade 2001-2011 is observed to be wide with maximum percentage of 57.51 in santravidas nagar and a minimum of 12.80 in badaun district giving an average of 27.85 per cent for the state. the distribution of the percentage of main non-agricultural workforce in rural population among the districts may conveniently be arranged into five grades of below 16, 16-24, 24-32, 32-40, and 40 and over (table 3). table-3.category wise distribution of rural non-agricultural work force, uttar pradesh, 2011 category % age no. of districts % to total districts very high 40 and over 12 16.90 high 32-40 13 18.31 medium 24-32 15 21.13 low 16-24 22 30.98 very low below 16 99 12.68 71 100.00 source: census of india, 1981, 1991 and 2001. considering the above mentioned five grades separately, we find that the districts under the first grade of 40 and over form three small but identifiable regions (fig. 3). two of them are found in the eastern region and one in the western plain region. about 18 per cent districts of the state lies under the high percentage grade and are found in two pockets. one region, relatively big in size occurs in the in the south-western part includes bulandshahr, hathras, aligarh, agra, firozabad and mathura districts, second lies in the northwestern part comprising the districts of saharanpur, bijnor and muzaffarnagar. the districts with percentage very close to the state average (27.85 per cent) occupying about 21 cent districts are scatteredly distributed over the state and fail to form a notable region in the state. about 31 per cent districts falling under the low percentage grade constitute a longitudinal zone which extends from siddhrathnagar in the east to jhansi in the south and etah in the west. only nine districts fall under the very low percentage grade constitute a continuous prominent region in the north-eastern and western parts which runs from balrampur in the east to budaun in the west. the other two districts of the same grade are detached from the main region. the general picture emerged from this discussion is that there is a gradual increase of main workforce in non-agricultural sector from north-western to south-eastern parts of uttar pradesh. 2.3. male non-agricultural workforce the regional distribution of male main workforce in non-agricultural sector of rural population is very similar to that of the main non-agricultural workforce. among the districts its proportion varies from 10.16 per cent in budaun to 59.34 per cent in santravidas nagar districts with a state average of 26.27 per cent. table-4. categorywise distribution of male non-agricultural workforce, uttar pradesh, 2011 category % age no. of districts % to total districts very high 40 and over 10 14.08 high 32-40 11 15.49 medium 24-32 18 25.35 low 16-24 16 22.54 very low below 16 16 22.54 71 100.00 source: census of india, 1981, 1991 and 2001. asian review of environmental and earth sciences, 2015, 2(2): 35-41 39 the graded distribution of male main workforce in non-agricultural sectors of rural population as depicted in fig. 4 shows that about one-fourth districts of the state fall under very low percentage grade (below 16 per cent) form a prominent region in the north-eastern and western part of the state. the other districts of similar grade are scattered too sporadically to form a distinct region. on the other hand, there are four small but definable regions of high percentage grade found in the eastern and western parts of the state. eighteen districts of the state fall under the grade of very close to the state average, eleven of them form a notable region in the eastern part of the study area. the other districts of the same grade are scattered and do not form any notable region. about 23 per cent districts fall under the low grade and form a number of small pockets of which a prominent region occurs in the south-western part. there are three regions of high percentage grade (32-40 per cent) which combinedly cover more than one-fifth of the districts of the state form a number of identifiable regions. among them one relatively big size occur in the southern part of the state. the general pattern is marked by gradual increase from west to south and to east in uttar pradesh. 2.4. female non-agricultural work force the pattern of regional distribution of female main non-agricultural workforce is quite different from that of general and male rural workforce. it varies from 12.82 per cent to 61.36 per cent giving an average of 35.52 per cent for the state. table-5. categorywise distribution of female main non-agricultural workforce, uttar pradesh, 2011 category % age no. of districts % to total districts very high 50 and over 14 19.72 high 42-50 14 19.72 medium 34-42 14 19.72 low 26-34 13 18.30 very low below 26 16 22.54 71 100.00 fig. 5 shows that the districts falling under the very high percentage grade of 50 and over constitute a longitudinal belt which extends from muzaffarnagar in the north to agra in the south. the other districts of same grade are too scattered to constitute a single continuous region in the state. on the contrary, the maximum number of districts (16) fall under the very low grade (below 26 per cent) and mainly concentrated in the eastern and southern parts which are separated by the region of high slab. about 20 per cent districts fall under the grade 42-50 per cent. these districts are grouped into a number of small regions of which the most prominent one occurs in the extreme eastern part comprising ballia, mau and deoria districts. the medium grade districts (34-42 per cent) constitute two discontinuous regions: one region, relatively large in size lies in the north-western part and the other in the eastern part. the low percentage grade is observed in the eastern part with a compact region comprised of eight districts. the other districts of this grade fail to form a notable region in the study area. the overall distribution depicts that there is a gradual decrease of female main workforce in nonagricultural sectors from west to south-east. 2.5. the simple correlation between rural non-agricultural workforce and independent variables in the present investigation, relationships have been sought between rural non-agricultural workforce and thirty nine variables of the districts of uttar pradesh. selection of each variable is based on an ability to develop a rational hypothesis of relationship between the variables and non-agricultural workforce. table 1 reveals that sixteen variables out of thirty nine are significant at confidence level of 99 per cent, though the actual magnitudes of their coefficients are different. x1 (literacy rate, r=0.521), x2 (rural literacy rate, r=0.511), x4 (male literacy rate, r=0.591), x5 (female literacy rate, r=0.440), x7 (educational institute/ student ratio, r=0.568), x10 (percentage of urban population, r=0.391), x12 (population density, r=0.731), x19 (no. of persons engaged in registered factories / lakh population, r=0.399), x20 (employees in public sectors (govt) / lakh population, r=0.306), x27 (percentage of net irrigated area to net sown area, r=0.387) and x36 (percentage of villages with linked road, r=0.335) are found to have direct relationship with rural non-agricultural workforce (y1). the variables x11 (percentage of rural population, r= -0.382), x22 (land utilization, r= -0.401), x23 (total cropped area, r= 0.367), x28 (person / cultivated area, r= -0.5.67) and x38 (no. of post office/ lakh population, r= -0.351) turn out to have a significant inverse relationship with y1. the variables which are significant and well above the stipulatedly acceptable 95 per cent level of confidence are: x8, x20, x31, x33 and x34. only two variables have inverse relationship with y1. table also shows that male rural non-agricultural workforce (y2) has similar reciprocal relationship between the same variables as has been found for y1. only ten variables are highly significant at 99 per cent level of confidence in their relationship with female nonagricultural workforce (y3). among them six variables namely: x1, x2, x5, x10, x12 and x27 are positively associated with y3. remaining four variables x11 (percentage of rural population, r= -0.373), x28 (person / cultivated area, r= 0.417), x34 (no. of doctors per lakh population, r= -0.390) and x38 (no. of post office/ lakh population, r= -0.372) are negatively associated with y3. six variables are namely: x4, x13, x16, x19, x26, and x36 are significant at 95 per cent level of confidence except x13 and x16. remaining four variables are positively associated with y3. this explanation leads to conclusion that agriculture, population growth and health facilities are the chief determinants but the magnitudes of their effects are dissimilar. asian review of environmental and earth sciences, 2015, 2(2): 35-41 40 table-1. co-efficient of correlation for non-agricultural workforce (total, male and female), and its correlates uttar pradesh, 2001 variables correlates correlation of coefficient non-agricultural workforce y1 y2 y3 x1 literacy rate 0.521* 0.501* 0.356* x2 rural literacy rate 0.511* 0.490* 0.366* x3 urban literacy rate 0.167 0.197 -0.201 x4 male literacy rate 0.591* 0.587* 0.277** x5 female literacy rate 0.440* 0.407* 0.397* x6 teacher/pupil ratio 0.171 0.193 0.005 x7 educational institute/ student ratio 0.568* 0.586* 0.202 x8 teacher/student ratio 0.289** 0.308* 0.085 x9 population growth (1991-2001) 0.210 0.207 0.124 x10 percentage of urban population 0.391* 0.354* 0.380* x11 percentage of rural population -0.382* -0.347* -0.373* x12 population density 0.713* 0.702* 0.355* x13 sex ratio 0.185 0.234 -0.273** x14 percentage of hindu population to total pop. 0.058 0.082 -0.100 x15 percentage of muslim population to total pop. -0.022 -0.056 0.173 x16 scheduled caste pop to total population -0.131 -0.106 -0.236** x17 population below poverty line 0.065 0.078 -0.077 x18 per capita income (at current price) 0.216 0.187 0.227 x19 no. of persons engaged in registered factories / lakh population 0.399* 0.369* 0.287** x20 employees in public sectors (govt) / lakh pop. 0.306** 0.307* 0.116 x21 no. of livestock population / lakh population -0.114 -0.108 -0.099 x22 land utilization -0.401* -0.391* -0.217 x23 total cropped area -0.367* -0.379* -0.046 x24 %tage of net sown area to total reporting area -0.062 -0.033 -0.190 x25 area sown more than once -0.218 -0.238** 0.104 x26 cropping intensity 0.106 0.077 0.291** x27 percentage of net irrigated area to net sown area 0.387* 0.333* 0.602* x28 person / cultivated area -0.567* -0.543* -0.417* x29 average size of land holding -0.186 -0.193 -0.071 x30 no. of tractors / 1000 ha. of cultivated land 0.068 0.044 0.132 x31 food production (mt) -0.286** -0.295** 0.022 x32 no. of medical(allopathic) institution/ lakh pop. 0.151 0.152 0.090 x33 no. of beds in hospitals/ dispensaries (allopathic)/ lakh population 0.296** 0.292** 0.152 x34 no. of doctors per lakh population -0.266** -0.227 -0.390* x35 no. of family welfare clinic / centres/ lakh pop -0.078 -0.054 -0.146 x36 percentage of villages with linked road 0.335* 0.309* 0.253** x37 percentage of electrified villages to inhabitant villages 0.127 0.143 0.002 x38 no. of post office/ lakh population -0.351* -0.329* -0.372* x39 no. of telegraph offices / telephone exchange /lakh population 0.038 0.047 -0.013 * significant at 1% level of confidence. ** significant at 5 % level of confidence. 3. conclusion the percentage of non-agricultural workforce improved from 12.3 per cent in 1971 to 13.78 per cent in 1981 and rose further to 27.85 per cent in 2011 in the state. in the case of both male and female rural nonagricultural work force, the percentage was almost static during 1981-2011, but there has been a significant increase during the period 2001-2011 both in the country and state. the regional variations in the distribution of workforce in rural non-agricultural sectors are quite notable. the general picture emerged that there is a gradual increase of main workforce in non-agricultural sector from north-western to south-eastern parts of uttar pradesh. the distribution of female main workforce in non-agricultural workforce depicts that there is a gradual decrease from west to south-east. the statistical analysis leads to conclusion that agriculture, population growth and health facilities are the chief determinants but the magnitudes of their effects are dissimilar. in the light of the above discussion the effort should be made for development of less developed areas, so that they may come up at par with developed areas, and the concept of planning with social justice proves successfully. references [1] census of india, "series 22, u.p," final report, population table, lucknow, 2004, 2001. [2] mellor and u. lele, "growth linkages of the new foodgrain technologies," indian journal of agricultural economics, vol. 28, pp. 3355, 1973. [3] w. mellor john, the new economics of growth-a strategy for india and the developing world, a twentieth century fund study. ithaca, new york: cornell university press, 1976. [4] j. unni, "regional variation in rural non-agricultural employment: an exploratory analysis," economic and political weekly, vol. 26, pp. 109-122, 1991. [5] a. vaidyanathan, "labour use in rural india: a study of spatial and temporal variations," economic and political weekly, vol. 21, pp. a130-146, 1986. asian review of environmental and earth sciences, 2015, 2(2): 35-41 41 [6] m. hossain, "credit for alleviation of rural poverty: the grameen bank in bangladesh," international food policy research institute (ifpri), research report 65. washington, dc1988. fig-3. based on census of india, 2011 fig-4. based on census of india, 2011 fig-5. based on census of india, 2011 views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 1, 8-15, 2014 http://www.asianonlinejournals.com/index.php/arees 8 the dynamics of land use land cover change: using geospatial techniques to promote sustainable urban development in ilorin metropolis, nigeria suleiman, y. m. 1 --saidu, s. 2 --abdulrazaq, s. a. 3 --hassan, a.b 4 --abubakar, a.n 5 1,2,3,4 laboratory of remote sensing and meteorology,department of geography, federal university of technology, minna, nigeria 5 department of urban and regional planning, niger state polytechnic, zungeru, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction studies have shown that there remain only few portions of the landscapes on the earth that is still in their natural state. due to anthropogenic activities, the earth surface is being significantly altered in some manner and man’s presence on the earth and his use of land has had a profound effect upon the natural environment thus resulting into an observable pattern in the land use and land cover over time. land is becoming a scarce resource due to immense agricultural and demographic pressure. hence, information on settlement growth i.e. consumption of new land with each unit of population growth and possibilities for their optimal use is essential for the selection, planning and implementation of land use schemes to meet the increasing demands for basic human needs and welfare. this information also assists in monitoring the dynamics of settlement expansion resulting out of changing demands of increasing population. studies on settlement expansion have become a central component in current strategies for managing land as a resource and in monitoring environmental changes. there has been tremendous growth and development in ilorin, the kwara state, capital in some aspect like building construction, road construction, deforestation and many other anthropogenic activities, since its inception in 1967 like every other state capital in nigeria. the aforementioned growth have led to increased consumption of land as well as modification and alterations in the originality of her land composition both land use and land cover over time without any comprehensive and pressing step ( as provided by remote sensing and gis data) to evaluate the status as it changes over time with view to detecting the land consumption rate and also make to predict same and the possible changes that may occur in this status so that planners can have a basic tool for planning. urban land is constantly and rapidly changing due to various human development activities and natural conditions. therefore, the management of urban environment involves procedures of monitoring and modelling which require reliable information base and robust analytical techniques. conventional surveying and mapping methods cannot deliver the necessary information in a timely and cost effective manner. remote sensing and gis given their cost effective and technological soundness are increasingly being used to develop useful sources of information and to support decision making in connection with a wide array of urban applications [1]. land change dynamics was studied and analyzed across the plains of metropolitan ilorin between 1986 and 2010. a statistical sampling design, landsat satellite data and geographical information system tools were used to efficiently identify patterns of land conversion. variability of change ranged from approximately 2 percent to greater than 50 percent, and progressed at an uneven pace. indicative of the changes is a sequence of agricultural expansion before 1986 followed by widespread conversion to built up area by 2000 and beyond. pattern and magnitude of conversions influenced by contextual conditions of land quality, population increase, plus economic and policy drivers. the sporadic expansion of settlements, especially the built up areas in and around the study area, resulted in rapid diminishing and conversion of other land cover types to more built up environment and thus aaccentuating urban agglomeration of ilorin. it is recommended that various government regulatory authorities embark on careful urban planning by strickly allocating land for various designated purposes and ensure continous monitoring of physical developments so as to safeguard distortions to the urban environment of ilorin. keywords: land use, land cover, environment, settlement, built up areas, geospatial techniques, http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(1): 8-15 9 this study is aimed at producing a layout of land use and land cover of ilorin at different epochs in order to detect the changes that have taken place particularly in the built-up land (settlement) and to predict changes that might take place in the same location over a given period using remote sensing techniques. 2. literature review land cover refers to the physical materials on the surface of a given parcel of land, while land use refers to the human activities that takes place on or make use of land e.g. residential, commercial, industrial etc. gupta and srivastava [2] described urban landscape as land use that is perceived as a way by which human beings utilize land while land cover exists as a natural environmental system. they stated further that change detection in land use and land cover can be obtained on a temporal scale such as by considering decades to assess landscape change resulted due to anthropogenic activities on the land. these anthropogenic activities on land are the consequence of rapid urbanization and industrialization. zubair [3] used remote sensing and gis technologies to detect the land use and land cover changes in ilorin, nigeria from 1972 to 2001 by landsat tm images of 1972, 1986, and 2001. he has used maximum likelihood algorithm of supervised classification method to delineate five land use and land cover classes for the study, namely: farmland, wasteland, forest, built-up and water-bodies. nigam [4] applied rs and gis for land use / land cover mapping and change detection in the rural urban fringe area of enchede city, the netherlands. he evaluated the effectiveness of high resolution satellite data and computer aided gis techniques in assessing the landuse change dynamics within enschede city, from 1993 to 1998 and thus hot links and user interface were developed so that the information can be provided to the user with a welldocumented procedure using arc view environment. however, there are still limitations in this study as delineation of built up boundaries was based on image classification alone. higher accuracy may be achieved using vegetation soil water [vsw] index or normalized difference vegetation index [ndvi] shigenobu, et al. [5] applied this approach to delineate new urban areas in bangkok metropolitan region in thailand. by the late 80s and early 90s most studies have gone beyond just monitoring urban growth to examining impacts of these growth on land use/land cover changes. abubakar, et al. [6] in their study on assessment of environmental degradation using satellite remote sensing technologies, examine landuse/landcover changes in talata mafara area of zamfara state, nigeria. their results showed that changes among six land use / land cover classes between 1986 and 1995, agricultural land increased from 117.00 km 2 to 158.50 km 2 , while grass, shrub and thicket land cover decreased from 20.13km 2 to 12.50 km 2 . there was a drastic increase in bare surfaces from 5.38 km 2 to 27.13 km 2 . settlement showed a slight decrease from 1.25 km 2 to 1.13 km 2 rather than the expected growth. uncultivated vegetated wetland also showed a decrease from 14.63 to 8.25 km 2 and water bodies increased from 3.88 km 2 to 5.00 km 2 . symeonakis, et al. [7] in their study on land use and land cover change and land degradation study in spain and greece using rs and gis succeeded in mapping the various types of lulc in alicante province in south east spain and the aegeon island of lesbos, greece. they achieved these using the land sat data and the fuzzy classification and convolution modules of erdas image 8.5 software. five (5) fuzzy layers per pixel were used and the resulting classified images were assessed using 100 random points and the aerial photographs as ground truth. the 1978 clssification indicate the catchment area was covered by various types of orchards, with an approximate area of 12392 ha of the entire catchment. the second lulc type in terms of area covered was matorral 7541 ha, thirdly is bare land 7363 ha, fourthly forest, 1039 ha, fifthly urban 889ha and lastly horticultural 879ha. for the year 2000 matorral had increased to 940 ha, orchard decreased to 895 ha, bare land decreased to 650 ha, horticulture increased to 2527 ha, urban increased to 1937 and forest decreased to 817 ha. 2.1. the study area the study area (ilorin) is the capital of kwara state. it is located on latitude 8 0 31’ n and 4 0 35’ e with total land area of about 100 km 2 [8]. it is situated on the transitional zone between the forest and the savanna region of nigeria and therefore serve as a “melting point” between the northern and southern culture”. ilorin falls into the southern guinea savanna zone. this zone is a transition between the high forest in the southern part of the country and the north with woodland characteristics. the geology consists of pre-cambrian basement complex with an elevation which ranges between 273 meter to 333 meter in the west and 200 meter to 364 meter in the east. the landscape of the region (ilorin) is relatively flat and this means it is on a plain and is dissected by two rivers; river asa and river oyun which form the core of the drainage system, flowing in a north – south direction and thus dividing the plain into two; western and eastern parts [9]. asian review of environmental and earth sciences, 2014, 1(1): 8-15 10 asian review of environmental and earth sciences, 2014, 1(1): 8-15 11 oyegun [10] noted that ilorin is one of the fastest growing urban centers in nigeria, with the rate of population growth and areal extent at a fast pace since 1967, which is much higher than for most cities in nigeria. he supported his claim, stating that ilorin the town had an estimated population of 40, 990 in 1952, 208, 546 in 1963, 474, 835 in 1982 and in 1984, the population was 480, 000. this trend in population growth is rapid and the growth rate between 1952 and 1963 according to oyebanji [11] is put at 16 percent which is higher than other cities in the country. the population as estimated by the 1991 population census was put at 570,000. 3. materials and methods the data used for this research include; (i) landsat satellite imageries of ilorin, kwara state for 1986, 2000 and 2010 were collected and utilized for this study. the 1986 and 2000 imageries were sourced from global land cover facility (glcf) and the 2010 imageries was sourced from national space research and development agency (nasrda), abuja, nigeria. (ii) arcgis 10.1 was used for the display and processing of the data, ilwis was used for the development of land use and land cover classes and for change detection analysis of the study area and idrisi; for projecting future change. (iii) markov chain and cellular automata analysis for predicting change was utilised for data analysis. markovian chain analysis describe land use change from one period to another and this is used to form the basis for projecting future changes. this is achieved by developing a transition probability matrix of land use change from time one to time two, which shows the nature of change while still serving as the basis for projecting to a later time period . (iv)the transition probability may be accurate per category basis. however, it does not provide knowledge of the spatial distribution of occurrences within each land use category. hence, cellular automata (ca) was used to add spatial character to the model. ca markov uses the output from the markov chain analysis particularly transition area file to apply a contiguity filter to “grow out” land use from time two to a later time period. in essence, the ca developed a spatially explicit weighting of more heavily areas that proximate to existing land uses. this ensure that land use change occurs proximate to existing like land use classes and not wholly random. 4. results and discussion figures 2, 3 and 4 depicts the pattern of land use land cover change in ilorin for 21 year period (1986 to 2010); and the projected change for the year 2020. the figures indicated increase in the percentage of built up areas and corresponding decrease in vegetal cover and farmlands asian review of environmental and earth sciences, 2014, 1(1): 8-15 12 figure-2.land use / land cover ilorin (1986) figure-3. land use/land cover of ilorin (2000) asian review of environmental and earth sciences, 2014, 1(1): 8-15 13 figure-4.land use / land cover of ilorin (2010) figure-5.land use land cover projection for ilorin (2020) asian review of environmental and earth sciences, 2014, 1(1): 8-15 14 table-1. categorised land use/land cover statistics for ilorin (1986) categories area covered (hectares) % of the total land cover bare lands 49409.1 21.6 forestland/vegetation 119588.1 52.2 built-up areas 28980.2 12.6 farmlands 30008.0 13.1 water bodies 1064.6 0.5 table-2. categorised land use/land cover statistics for ilorin (2000) categories area covered (hectares) % of the total land cover bare lands 33105.1 14.5 forestland/vegetation 119588.1 52.1 built-up areas 41026.2 17.9 farmlands 43266.0 15.0 water bodies 1064.6 0.5 table-3. categorised land use/land cover statistics for ilorin (2010) categories area covered (hectares) % of the total land cover bare lands 33805. 1 14.8 forestland/vegetation 111116.0 48.5 built-up areas 49863.2 21.8 farmlands 33205.1 14.5 water bodies 1060.6 0.4 table-4. categorised land use/land cover statistics for ilorin (2020) categories area covered (hectares) % of the total land cover bare lands 35044.6 10.0 forestland/vegetation 104675.9 20.0 built-up areas 58178.7 59.8 farmlands 30463.6 10.0 water bodies 687.1 0.2 tables 1, 2, 3 and 4 shows the classifications of land use and land cover in ilorin. five categories were identified; namely; bare lands, forested/vegetated lands, built up areas, farmlands and water bodies. as at 1986, forest and other vegetal covers account for over 52 percent of total land cover of ilorin. the built up areas and water bodies accounted for 12.5 percent and 0.5 percent respectively (table 1). however, built up areas increased from 12 percent in 1986 to 18 percent in the year 2000. within the same period, bare land decreased from 21 percent to 14 percent. no significant change was recorded in other land use patterns (tables 2, 3 and 4). table-5.comparative distribution statistics of land use land cover pattern forilorin (1986 2020) year categories 1986 2000 2010 2020 bare lands 21.6 14.5 14.8 10.0 forestland/vegetation 52.2 52.1 48.5 20.0 built-up areas 12.6 19.3 21.8 59.8 farmlands 13.1 13.6 14.5 10.0 water bodies 0.5 0.5 0.4 0.2 total 100 100 100 100 it became evident that enormous changes in land use occurred as a result of sporadic urban growth that ilorin witnessed in recent times. the territorial extent of farmlands, vegetation and water bodies have been greatly tampered with, as a result of human activities through exploitation and development of built up areas. the continuous increase in built up areas is due to increase in the inflow of population that places heavy demand on the environment and thus leading to great increase in the size of the settlement in both the city center and the surburbs (table 5). the land use land cover change projection to the year 2020 shows that there is going to be further population increase in ilorin. this will be necessited by net gain due to immigration and uncontrolled birth rate. 5. conclusion and recommendations the sporadic expansion of settlements, especially the built up areas in and around the study area, resulted in rapid diminishing and conversion of other land cover types to more built up environment and thus aaccentuating urban agglomeration of ilorin. it is recommended that various government regulatory authorities embark on careful urban planning by strickly allocating land for various designated purposes and ensure continous monitoring of physical developments sos as to safeguard distortions to the urban environment of ilorin. references [1] x. yang and c. p. lo, "using a time series of normalized satellite imagery to detect land use/cover change in the atlanta, georgia metropolitan area," international journal of remote sensing, vol. 23, pp. 1775–1798, 2002. asian review of environmental and earth sciences, 2014, 1(1): 8-15 15 [2] r. d. b. gupta and s. k. srivastava, monitoring of change in landuse/landcover using multi sensor satellite data. india: national institute of technology allahabad, 2004. [3] a. zubair, "monitoring the growth of settlement in ilorin, nigeria (a gis and remote sensing approach)," the international archives of the photogrammetry, remote sens. spatial info. sci., vol. 37, pp. 225-232, 2008. [4] r. k. nigam, application of remote sensing and gis for landuse/landcover mapping and change detection in the rural-urban fringe area of enschede city, the netherlands. netherlands: international institute for aerospace survey and earth sciences (itc) enschede, 2004. [5] t. shigenobu, o. tran shiro, and y. yushifumi, "monitoring of long-term urban expansion by the use of remote seneing images for different sensors; in bangkok metropolitan persia," japan remote sensing journal, vol. 17, pp. 54-64, 2003. [6] s. m. abubakar, y. r. kudanmiya, and p. n. eyong, "assessment of environmental degradation using satellite remote sensing technologies in talata mafara area, northern nigeria," environmental review, vol. 4, pp. 577-586, 2002. [7] e. symeonakis, a. calvo, and e. arnau, "a study of the relationship between landuse changes and land degradation in spain and greece using rs and gis rs and gis," proceedings of the international conference of gis and rs in hydrology, water rescues and environment, gorges dam china. september 2003, 2003, pp. 16-19. [8] kwara state of nigeria, kwara state diary. ilorin: government press, 1997. [9] j. o. oyebanji, "indicators of level of living in nigeria," proceedings of the 29th annual conference of nigerian geographical association, 1986. [10] r. o. oyegun, water resources in kwara state. ilorin: matanmi and sons printing and publishing co. ltd, 1983. [11] j. o. oyebanji, social indicators and quality of life in nigeria; the state of the art. in: rural nigeria: development and quality of life: university of nigeria, 1983. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 3, 56-60, 2014 http://www.asianonlinejournals.com/index.php/arees * corresponding author 56 determinants of land holding size among rice farmers in southeast, nigeria ben-chendo g.n. 1* --o.c. korie 2 --u.a. essien 3 --i.j. uhuegbulem 4 1,2,3,4 department of agricultural economics federal university of technology owerri imo state, nigeria. abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction .................................................................................................................................................................................................... 57 2. methodology .................................................................................................................................................................................................... 57 3. results and discussion.................................................................................................................................................................................... 58 4. conclusion ....................................................................................................................................................................................................... 60 references ........................................................................................................................................................................................................... 60 this study identified determinants of land holding size of rice farmers in anambra state, southeast nigeria. a multistage sampling technique was used in sample selection. six autonomous communities were chosen purposively based on the consideration of rice farming activities in these rural communities. the sample frame was 182 rice farmers. from this sample frame, twenty rice farmers were randomly selected from 6 rice farming communities giving a sample size of 120 but 99 were valid. data were collected with structured questionnaire from 120 randomly selected rice farmers. data were collected on the socioeconomic variables, land sizes, land amendment practices.. data were analysed using descriptive statistics; ordinary least squares multiple regression techniques. the results showed that rice farmers in the study area were predominantly male (78.79%) with a mean age of 44.2years and household size of 8persons.their major method of land acquisition is through communal followed by inheritance, lease and purchase. the average land size cultivated on was 1.66ha.the multiple regression analysis showed that factors such as sex, farming experience, method of land acquisition, annual off farm income and lease price of rice farmers influenced their landholding size. it is therefore concluded that with government intervention farmers can have access to increased land sizes which will invariably improve technology use and the level of profit would increase. keywords: land ownership, amendment, practices, size, rice, determinants http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(3): 56-60 57 1. introduction although rice grows well in all the six geo-political zones of nigeria, the demand for polished long grain, stone free and odorless rice by the urban dwellers has fueled the demand for imported rice. total demand for rice in nigeria is put at about 5million mt a year out which about 3.2 million mt are produced locally. erenstein, et al. [1] observed that the demand and supply gap in rice production is widening, resulting in huge import bill on rice. the high cost of importation in recent years has highlighted the desire by the government to encourage import substitution by encouraging increased local production. locally produced rice at present is uncompetitive in the market because its value chain is fragmented and cannot offer a standard. it is fraught with poor quality-presence of extraneous materials such as stones and debris. most farmers in nigeria keep on operating patches of small holdings; as a result rice production is mostly dominated by small holder producers who employ traditional practices and primitive technology resulting to a negligible quantity in production and supply of the commodity which result to a meager income which could not provide decent existence for farm family. secondly because all operations are manual with limited farm sizes, cost of production is also high. this is in spite of the fact that nigeria has very favorable ecologies for rain fed lowland, irrigated lowland as well as upland rice production. total potential land for irrigated rice production is estimated at 1.6 million hectares out of which only 47, 798ha is available. there had been reported decrease in farm size and consequently fallow length which has adversely affected the resource base due to increasing population pressure on the available land [2]. in the absence of sound management practices or the economic use of fertilizer and other additives, declining fallow periods results to accelerated periods of leaching of nutrients, increased weed population, erosion and decreased moisture retention [3, 4]. manure, whether organic or inorganic helps to enhance plant development. the major purpose of manure or fertilizer application is to improve soil fertility and increase yield of crops. in crop production, proper and adequate plant nutrients are required for an enhanced crop establishment, growth and yield. nakkiran and karthikeyan [5] opined that fragmentation of scattered pieces of land contributes to the difficulties of getting effective soil conservation measures implemented and increases the labour and time required in agriculture. however, crop production can be influenced by the source of nutrient involved in its production [6]. reduced portion of arable land have led to the abandonment of the traditional methods of land use and overexploitation of the land have resulted to land degradation. it means that if overcrowding on the arable land leads to less efficient methods of production, then food production would actually decrease as population increase. for instance, nweke [7] pointed out that average holding on farm land is less than 1.5 hectares per family in addition to another 0.2 hectares of compound land. this implies that the farmers may have small plots of land scattered some distance from his home. even the size of holdings and of individual plots according to eboh [8] is further reduced by fragmentation due to division of farm land among heirs. therefore, some scholars [2, 9, 10] are of the view that farm size is to a large extent a reflection of pressure on land. this work is set to achieve the following objectives -analyse the socio-economic characteristics of the farmers -isolate the determining factors to land size holding -determine the land amendment practice 2. methodology the southeast is made up of five states; anambra, imo, abia, ebonyi and enugu and rice is being produced in all these states. the zone is located at the tropical rain forest with thick vegetation. demographically the zone has a population of sixteen million three hundred and eighty on thousand seven hundred and twenty nine (16,381,729) which is approximately 12% of the entire population of nigeria [11]. the multistage sampling technique was used in sample selection. this was used in order to enable the researcher capture a significant position of the characteristics of the farmers at different stages and to ensure a good spread of the data. in the first stage, two states were randomly selected and three local government areas and six autonomous communities were purposively selected (3 each) from the twentytwo autonomous communities on the consideration of rice farming activities in these rural communities. ten informants from each of the six sampled communities were selected to aid generation of the list of rice farmers. the sampling frame was 182 (list of rice farmers in each village within the selected autonomous rural communities involve in rice farmers). from this sampling frame, twenty rice farmers were randomly selected giving a sample size of 120. data were collected from primary and secondary information sources. the study made use of a well-structured questionnaire and journals, bulletins and textbooks. twenty one questionnaires were invalid and just 99 questionnaires were used for further analysis. data were analyzed using descriptive statistics such as frequency, percentages and mean, and multiple regression analysis. a multiple linear regression model was employed and is expressed as y = f ( x1, x2, x3, x4, x5, x6, x7, x8, x9, e) ……………………………(1) where, y = land holding size in hectares x1 = sex (dummy, 1 for male; 0 for female). x2 = age of farmer (years). x3 = marital status (dummy 1 for married; 0 for otherwise) x4 = household size (number of persons). x5 = level of education (years) x6 = farming experience (years). x7 = method of land acquisition (dummy, 1 for communal; 0 for otherwise). x8 = off farm income of farmer per annum (naira). x9 = lease price per hectare (naira). e = error term. asian review of environmental and earth sciences, 2014, 1(3): 56-60 58 four functional forms were fitted to the data. these include the linear, semi – log, doublelog and the exponential functions. the function that gives the best fit was selected based on the magnitude of the coefficient of the multiple determination (r 2 ) and the size and signs of the estimated coefficients and the statistical significance of the parameter estimates. 3. results and discussion table 1 showed that 78.78% of rice farmers were male while 21.21% were female. this shows that majority of the respondents were male. this fact goes a long way to show the domination of the male sex in rice farming due to the nature of the job which is mostly strenuous for their female counterpart and also the pattern of land ownership in the study area. this agrees with the findings of olaleye [12] that small scale farming are being carried out mostly by males, while the females involve in light farm operations such as harvesting, processing and marketing. the mean household size was 8 persons. this shows that most of the respondents have a larger family size that assists them in their farming activities; also it will continue to reduce land area available for individual farmers in the future. this disagrees with the findings of ogungbile and olukosi [13] that in nigeria the average family size is about 67 persons per family. the method of land acquisition was mainly communalthe mean level of education of rice farmers is 8.1 years. this implies that most of the farmers obtained at least primary education. this feature makes them capable of understanding and adopting available innovations that encourages rice production. the mean level of experience of rice farmers was 7.95 years. this implies that most of the farmers interviewed have been in the business for a reasonable number of years. this period would have exposed them to various challenges associated with rice production and therefore would have found adaptive strategies to those challenges hence better productivity. rice farmers acquire land through communal land tenure system. the mean farm size available to each farmer was 1.66 hectares. it could be deduced that large expanse of land was not available to majority of the farmers; thus extremely limiting commercialization and productivity in agriculture in the study area. the mean lease price per hectare was n12,676 which was high considering that farmers in the rural areas are pro-poor. table-1.socio-economic characteristics of the respondents n=99 characteristics frequency percentage sex male female age (mean=44.2years) 30-39 40-49 50-59 60-69 marital status married single household size (mean-8persons) 2-7 8-13 14-19 method of land acquisition communal inherited lease purchase farming exp. (mean-7.95years) 1-5 6-10 11-15 educational attainment (mean=8.1yrs) 1-6 7-12 13-18 lease price/ ha (mean=n12,676) 10.00015,000 16,000-20,000 off farm income sources trading artisan hairdressing civil servant land holding size (ha) (mean=1.66ha) 0.5 – 0.9 1.0 – 1.4 1.5 – 1.9 2.0 – 2.4 2.5 – 2.9 total 78 21 48 22 13 16 93 6 45 50 4 56 32 8 3 31 64 14 29 55 15 34 65 62 22 6 9 1 26 57 10 5 99 78.79 21.21 48.48 22.22 13.14 16.16 93.94 6.06 45.45 50.51 4.04 56.57 32-23 8.08 3.03 31.31 64.65 14.14 29.29 55.56 15.15 34.34 65.66 62.63 22.22 6.06 9.09 1.01 26.26 57.58 10.10 5.05 100 source: field survey, 2013 asian review of environmental and earth sciences, 2014, 1(3): 56-60 59 isolate the factors influencing landholding size in the study area table-2. factors influencing land holding size in the area explanatory variable linear form semi-log form double-log form exponential form sex(x1) 0.623993 (1.799542)* 0.94809 (1.625663) 0.189584 (1.921738)* 0.23917 (1.946059)* age (x2) -0.00558 (-0.36003) -0.92589 (-0.81704) 0.065396 (0.34115) -0.00056 (-0.10109) marital status(x3) -0.11319 (-0.35323) -1.05554 (-1.61889) -0.00038 (-0.00342) 0.15808 (1.391828) household size (x4) -0.04064 (-0.74812) 0.45164 (0.930798) -0.04402 (-0.5363) -0.02101 (-1.09114) levelof education (x5) 0.017495 (0.669746) -0.09631 (-0.35798) 0.05746 (1.262645) 0.014442 (1.559893) farming experience(x6) 0.041813 (2.591611)** 1.03859 (2.059167)** 0.066407 (0.778349) 0.003393 (0.593372) method of land acquisition(x7) -1.21663 (-3.01443)*** -1.40679 (1.82925)* -0.38953 (-2.99432)*** -0.59006 (-4.12489)*** offfarm income of farmer (x8) 0.00000331 (2.646787)** 2.222085 (3.303207)*** 0.322954 (2.838112)*** 0.000000445 (1.002659) lease price (x9) 0.000518 (8.890965)*** 2.126741 (4.179953)*** 0.4745 (5.513241)*** 0.00000736 (3.564822)*** constant 0.791164 -39.3209 -7.06033 0.718748 r 2 0.969815 0.913886 0.940657 0.908676 fvalue 142.7958 47.16693 70.44972 44.22252 degree of freedom 90 90 90 90 no of observation(n) 99 99 99 99 source,fieldsurvey,2013 **significantat5%level *significantat10%level ***significantat1%level. figures in parenthesis are t-ratios. table 2 shows that four functional forms of the multiple regression analysis models were tried, out of the four functional forms estimated, the linear functional form provided the best fit and hence chosen as the lead equation. this choice was based on the premise that it has the highest number of t-values that were statistically significant at 1%, 5% and 10% level. it also showed a relatively higher r 2 and f-value of 0.97 and 142.8 respectively. the r 2 value implies that 97% of the variation in the farmers land holding size is explained by the variations in the independent variables included in the model, while the remaining 3% of variation in farmers land holding size is explained by other variables not included in the model. the f-value of 142.8 shows that the proportion of the explained variation on the dependent variables is statistically significant at 0.01 levels which implies that the model is adequate for use for further analysis. the result showed that factors such as sex(x1), farming experience(x6), method of land acquisition(x7), income of farmers(x8) and lease price(x9) significantly influence the land holding size in the study area. sex(x1) which showed a positive relationship with land holding size and significant at 10% level of probability. this could be that the workload involved in rice production makes men in the enterprise more productive than the women; this therefore implies that landholding size is increased as the productive sex increase. age(x2) of farmers showed an inverse relationship with landholding size but not significant. this implies that as the age of rice farmers increases the landholding size decreases. marital status(x3) showed an inverse relationship with landholding size but not significant. this implies that marital status of respondents in the study does not influence landholding size. household size(x4) also showed an inverse relationship with landholding size but not significant. this implies that as the household size increases the landholding size decreased. this may be due to sharing of farmlands among households as a result each individual would be entitled to small portion of land to cultivate. level of education(x5) of farmers showed a direct relationship with landholding size but not significant. this implies that as the farmers level of education increased the landholding size increase as well. farming experience(x6) showed a positive relationship with landholding size and significant at 5% level of probability. this implies that as the years of farming experience of respondents increased the land holding size also increased because farmers with highest number of years of experience in farming will have good skill and better approaches to farming operations and would want to obtain more farmlands inorder to expand production which leads to increased productivity. method of land acquisition(x7) showed a negative relationship with landholding size and significant at 1% level of probability. this implies that as method of land acquisition decreases the landholding size decreases. the decrease in land acquisition was due to the prevalence of communal landholding system in the area resulting to fragmentation of land among members of the community, this is so because the land belongs to the entire community, as a result no member of the community is permitted to use the land without permission from leaders of the community and individuals are given small portion of land on which they could cultivate. asian review of environmental and earth sciences, 2014, 1(3): 56-60 60 income of farmers(x8) showed a positive relationship with landholding size and significant at 5% level of probability. this implies that as the income of farmers increased the landholding size also increase. this implies that farmers with higher equity is capable of purchasing or obtaining larger size of farm in order to expand production and also enjoy the economies of scale thereby leading to higher productivity. lease price(x9) showed a positive relationship and significant at 1% probability. this implies that as landholding size increases the lease price increased. this relationship supports the law of supply which says that the higher the price the higher the quantity supplied. examine the soil amendments practices adopted by the farmers to improve production. table-3. frequency distribution of land amendment practices adopted by the rice farmers land/soilamendment practices *frequency percentage fertilizers 95 95.96 pesticides 58 58.58 herbicides 30 30,30 insecticides 15 15.15 irrigation system 4 4.04 increased fallow length 20 20.20 other amendment practices 31 31.31 source: computed from field survey, 2013.*multiple responses were recorded the table showed that 95.96% used fertilizers, 58.58% used pesticides, 30.30% used insecticides, 15.15% used the irrigation system, 404% practiced increased fallow length, 20.20% increased fallow length while 31.31% did other soil amendment practices. this implies that the soil amendment practices mostly done by farmers are the use of fertilizers and other agrochemicals. also, farmers do more of the land amendment practices as these practices helps in the improvement and sustainability of the farmers’ physical production and hence increased productivity. 4. conclusion this study has brought to the open that the land holding size of the rice farmers is relatively small and can discourage the practice of rice farming. there is need for the enhancement of land holding size so that rice farmers would optimize resources used in rice production. references [1] o. erenstein, l. frederic, s. o. akande, s. o. titilola, g. akpokodje, and o. o. ogundele, the nigerian rice economy in a competitive world: constraints, opportunities and strategic choices. rice production systems in nigeria: a survey. côte d’ivoire: west africa rice development association (warda) abidjan, 2003. [2] i. i. osugiri, "effect of population on agricutural productivity in imo state," an unpublished msc. thesis, university of nigeria, nsukka, nigeria, 1996. [3] r. lal, "erosion caused productivity decline in soils of the humid tropics," soil taxonomy news, vol. 5, pp. 4-11, 1983. [4] spore, "sustainable soil oroductivity in intensive," agriculture cta bi-monthly bulletin, vol. 49, pp. 1-2, 1994. [5] s. nakkiran and m. karthikeyan, cooperatives and agribusiness. new delhi-110 002: discovery publishing house pvt. lmt, 2012. [6] i. d. hodge, "rights to cleared land and the control of dry land-seepage salinity," australian journal of agricultural resource economic society, vol. 26, pp. 185-201, 1982. [7] f. i. nweke, "the role of market factors in the small cropping systems of southern nigeria," can j. agric. econs., vol. 28, pp. 67-69, 1980. [8] e. c. eboh, "agriculture intensification and factor productivity in anambra state of nigeria: a case study," phd thesis, university of nigeria, nsukka, nigeria, 1990. [9] b. a. dattoo, "relationship between population density and agricultural systems in the ihuguru mountains – tanzania," journal of tropical geography, vol. 2, pp. 1-12, 1976. [10] w. allan, the african husbandman. edinburgh united kingdom: oliver and boyd publishers, 1965. [11] npc, national population census. national population commission vol. 1. abuja, nigeria, 2006. [12] r. olaleye, "effectiveness of development intervention for economic empowerment on rural women in ondo nigeria," an unpublished ph. d thesis submitted to the department of agricultural extension and rural development, university of ibadan, ibadan. vol. 1, 2000. [13] a. o. ogungbile and j. o. olukosi, "an overview of the problems of resource poor farmers in nigeria agriculture. appropraite agricultural technologies for resource poor farmers," in proceedings of nigeria national farming systems research network workshop in calabar, cross river state, august 14-16, 1991, pp. 21-31. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 2, 35-38, 2014 http://www.asianonlinejournals.com/index.php/arees 35 preliminary phytochemical, antimicrobial and proximate analysis of tender leaves of psidium guajava l in jos, plateau state, nigeria egga, e.s. 1 --adeyanju, o. 2 --agyeno, o.e. 3 1,2 department of chemistry, university of jos, p.m.b 2084, jos, plateau state, nigeria 3 department of plant science technology, university of jos, jos, plateau state, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction guavas are plants in the myrtle family (myrtacease). common names are guava (english), gioba (hausa), goifa (yoruba), gova (igbo), guayaba (spanish), goyave (french), goeajaaba (dutch), [1]. a native of tropical america, it is now planted as a fruit tree in west africa. the seeds are distributed by man, and animals, (mainly monkey and birds) and are cultivated throughout the tropics. a small tree of about 68m high, bark is grayish brown, hard or very rough and resistant to termites. the fruits are up to 4 inches long, fleshy, globosely, ovoid or pear-shaped; generally yellowish or white when ripe. they contain a mass of small seeds embedded in the endocarp, though some are seedless or nearly so. it is said to be higher in vitamin c than citrus – 80mg of vitamin c in 100g of fruit and also contains an appreciable amount of vitamin a [1]. the seeds are numerous, flattened and kidney-shaped. the plant is angiospermic and dicotyledonous. leaves are up to 4.5 inches long, opposite, elliptic/ellipsoidal and the veins are prominent on the lower surface. the tender leaves are a lighter shade of green than the matured leaves and are curly and unfurling. the leaves of psidium guajava are aromatic when crushed. the flowers are white, singly borne on short stalks in leaf axis, sepals 4, and petals 5. leaves are scented and contain 6% of fixed oil, 0.365% of a cineolbased essence, 3.15% resin, 8.5% tannins and other metabolites. [1]. the main components of the essential oil are pinene, β-pinene, limonene, β-bisobolene, caryophyllene oxide, β-copanene, quercetin and curcumene [2]. the essential oil from the leaves has also been shown to contain nerolidol, β-sitosterol, ursolic and guayavolic acids have also been identified [3]. leaves are particularly rich in flavonoids and distinctly rich in quercetin [4]. much of the leaves therapeutic activity is attributed to the flavonoids, they demonstrate great antibacterial activity [5]. quercetin (fig 1) is thought to contribute to the antidiarrhoeal effect of psidium guajava leaves. it is able to relax intestinal smooth muscle and inhibit bowel contraction [6]. the leaf methanolic extract also showed in vitro antimicrobial activity against escherichia coli, salmonella typhi, staphylococcus aureus, proteus mirabilis and shigella dysenteria [3]. the effectiveness of the leaf extract against staphylococcus aureus and a strong antimicrobial action have been reported on gram-positive and gramnegative organism [7]. the flavone derivatives isolated were reported to inhibit the growth of staphylococcus aureus in a dilution of 1:1000 [5]. the leaves of guava tree in decoction are recommended for gastroenteritis, chronic diarrhea etc. the young leaves and shoots are used for dysentery and diarrhea [8]. it has been reported that the phytochemical screening, proximate, chromatographic analyses and the antimicrobial activities of tender leaves of psidium guajava of the family myrtaceae, were carried out. the phytochemical screening revealed the presence of all metabolites and compounds tested for such as flavonoids, tannins, reducing sugar, terpenes, saponins, anthraquinones and alkaloids. the proximate analysis gave a moisture content of 3.67%, ash value of 3.295%, acid insoluble ash of 0.25%, alcohol soluble extractive value of 21.34%and water extractive value of 3.54 %. the antimicrobial screening of methanol extract showed activity against the tested organisms. the antimicrobial screening of hexane and ethyl acetate also showed activity against the tested organisms. the result indicated that the leaves had a potential antimicrobial activity and was concentration dependent. the chromatographic analysis of the extracts showed presence of variety of compounds. this therefore, supports the traditional medical use of psidium guajava. keywords: antimicrobial, phytochemical , proximate analysis, psidium guajava, chromatographic analysis, jos. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(2): 35-38 36 quercetin present can inhibit the intestinal movement and reduce capillary permeability in the abdominal cavity and this may explain the antidiarrheal mechanism of psidium guajava extract [8]. in addition, other flavonoids and triterpenes in guava leaves e.g quaijavar in (fig 2) show antispasmodic activity [9]. guava leaves also have antioxidant properties which are attributed to the polyphenols in the leaves. tender leaves are chewed to bring relief in tooth ache (analgesic) in ghana [10]. they are chewed for stomach ache and piles [10]. when boiled with lemon grass (cymbopogon citrates), an adjuvant, the decoction is used to cure cough. this decoction is also taken in senegal for tracheobronchitis [10]. the active principles of many drug found in plants are secondary metabolites [4]. therefore, basic phytochemical investigation of its extracts for major phyto-constituents is also vital. in the present study the extracts of psidium guajava were screened for phytochemical constituents, antimicrobial activity and proximate analysis. 2. materials and methods plants used for this study were collected from jos metropolis, plateau state, nigeria. the identity of plant materials was confirmed and authenticated at the herbarium of the department of plant science technology, university of jos. 2.1. preparation of plant extracts the plant material was dried at room temperature and then powdered using a grinder. the powdered sample (100g) was subjected to soxhlet extraction using 300ml of each of the solvents (methanol, hexane and ethyl acetate). the resulting extracts were concentrated on a hot water bath and kept for further investigation. 2.2. phytochemical screening phytochemical screening for major constituents was undertaken using standard qualitative methods [11]. the extracts were screened for the presence of glycosides, alkaloids, tannins, flavonoids, saponins, anthraquinones and terpenes. 2.3. test organisms standard strains of s. aureous, s. pyogenes, bacillus subtilis, candida albicans and pseudomonas aeruginosa were obtained from the department of medical microbiology, jos university teaching hospital, jos, nigeria. 2.4. antimicrobial screening mic of the ethanolic and aqueous extract of psidium guajave which showed the highest antibacterial activity in the disc diffusion assay were determined based on broth dilution technique with a standard method [12]. inoculation of microorganisms were prepared from 12 hours broth cultures. stock solutions of extracts (4000µg/ml) were diluted with nutrients broth cultures. stock solutions of extracts (4000µg/ml) were diluted with nutrient broth in serial tenfold dilutions using nutrient broth to make dilution ranging from 250µg/ml to 4000µg/ml and inoculated with 0.2ml of the test microorganisms. the inoculated tubes were then incubated at 37 0 c for 24hours and were inspected for non-turbidity. the lowest concentration of the extract which prevented visible growth was noted and recorded as the minimum inhibitory concentration (mic). 2.5. proximate analysis analysis of tender leaves of psidium guajava for moisture content, total ash, acid insoluble ash, alcohol extractive value and water extractive value using a standard method by trease and evans [13] was carried out. asian review of environmental and earth sciences, 2014, 1(2): 35-38 37 table-1. phytochemical screening of methanol, hexane and ethyl acetate extracts of tender leaves of psidium guajava methanol extract hexane extract ethyl acetate extract flavonoid ++ + tannins +++ ++ reducing sugar + + + terpenes ++ + saponnins + ++ + anthraquinones +++ ++ + alkaloid + ++ +++ = high concentration; ++ = moderate concentration; + = low conc.; = absent table-2. proximate analysis of tender leaves of psidium guajava moisture content 3.67% total ash 3.29% acid insoluble ash 0.25% alcohol extractive value 21.34% water extractive value 3.54% table-3. rf values for 70% methanol, hexane and ethyl acetate extracts spots 70% methanol hexane ethyl acetate 70% methanol hexane ethyl acetate 1 0.8167 0.51 0.35 0.7142 0.58 0.4761 2 0.95 0.816 0.533 0.8571 0.827 0.6507 3 0.933 0.8167 0.9523 0.931 0.7619 4 0.883 0.8730 5 0.95 0.9047 6 0.9523 7 table-4. minimum inhibitory concentration (mic) of the tender leaves of psidium guajava (methanol extract) against tested microorganisms test organism concentration µg/ml 250µg/ml 500µg/ml 1000µg/ml 2000µg/ml 4000µg/ml pseudomonas aeruginosa 0+ + + bacillus subtilis 0+ + + + candida albicans 0+ + + streptococcus pyogenes 0+ + + + staphylococcus aureus 0+ + + o+ = minimum inhibitory concentration; + = inhibition; = no inhibition (turbidity) table-5. minimum inhibitory concentration (mic) of the tender leaves of psidium guajava (hexane extract) against tested microorganisms test organism concentration µg/ml 250µg/ml 500µg/ml 1000µg/ml 2000µg/ml 4000µg/ml pseudomonas aeruginosa 0+ + + bacillus subtilis 0+ + + + candida albicans 0+ + + streptococcus pyogenes 0+ + + + staphylococcus aureus 0+ + + o+ = minimum inhibitory concentration; + = inhibition; = no inhibition (turbidity) table-6. minimum inhibitory concentration (mic) of the tender leaves of psidium guajava (ethyl acetate extract) against tested microorganisms test organism concentration µg/ml 250µg/ml 500µg/ml 1000µg/ml 2000µg/ml 4000µg/ml pseudomonas aeruginusa 0+ + + + bacillus subtilis 0+ + + candida albicans 0+ + + streptococcus pyogenes 0+ + + staphylococcus aureus 0+ + + o+ = minimum inhibitory concentration; + = inhibition; = no inhibition (turbidity) asian review of environmental and earth sciences, 2014, 1(2): 35-38 38 3. result the results of the phytochemical screening, proximate analysis, antimicrobial tests for the methanol, hexane and ethyl acetate are presented in tables 1-6. 4. dicussion phytochemical screening (table 1) revealed the presence of flavonoid, tannins, reducing sugar, terpenes, saponins, anthraquinones and alkaloid. the chemical constituents present in the extracts have some therapeutic values. tannins are plant metabolites well known for their antimicrobial properties [14]. flavonoids have both antifungal and antibacterial activities. they possess anti-inflamatory activity [3, 15]. flavonoid, terpenes and alkaloid are known to have antimicrobial and bactericidal properties against several [11]. in the antimicrobial studies, the majority of the organisms were more sensitive to methanolic extract. according to trease and evans [13], the anti-bacterial activity and inhibitory effect of plant extracts may be due to the presence of secondary metabolites. in table 4, the methanolic extract of tender leaves of p. guajava was active against the entire microorganisms. it has mic value of 500μg/ml against bacillus subtilis and streptococcus pyogenes, 100 μg/ml against pseudomonas aeruginosa, candida albicans, and staphylococcus aureus. these findings are consistent with etuk, et al. [16] who reported that the bark extract of p. gaujava had antidiarrheal activity in vitro. previous reports have demonstrated the antidiarrheal activity of tannins [17], flavonoids [18] and saponins [9]. in table 2, the low moisture content (3.67%) implies that the plant can be stored for a long time and not affected by microbial attack. the ash content (3.29%) buttresses the claim that it is highly organic and medicinal. in table 3, the components of the extract separated on the plates showed that variety of compounds are present in the extracts. 5. conclusion the result of this experiment showed that tender leaves of p. guajava may have some valuable anti-microbial activities. this property tends to support the traditional medicinal stage in the treatment of bacterial infections. the result justified the use of the plant in the treatment of diseases of microbial origin in herbal medicine. 6. contribution/ originality of this study this study contributes to the existing literature and the scientific justification of the medicinal potential of this plant. the findings in this research validate its use among the low income people such as farmers, villagers and native communities. it is also likely to establish a scientific bases and proof for its potential use in folk medicine for the treatment of infectious diseases produced by common pathogenic microorganisms. reference [1] h. m. burkhill, the useful plants of west tropical africa vol. 4. london: the british printing company limited, 1997. [2] m. b. zakaria and m. a. mohd, "traditional malay medicinal plants," journal of science forum, vol. 1, pp. 34-36, 1994. [3] m. m. iwu, "plant flavonoids in biology and medicine," in proceeding of 4th annual conference of the nigeria society for pharmacology. university of nigeria nusukka, 1984. [4] a. abok, a. a. adeyemi, and i. a. jegede, "spectrophtometric estimation of anthraquinone content and antimicrobial potentral of extracts of some cassia species used in herbal medicine in ibadan nigeria," sci. forum., vol. 3, pp. 57-63, 2000. [5] b. oliver-bever, medicinal plants in tropical west africa. cambridge university press, 1986. [6] g. d. pamplona-roger, encyclopedia of medicinal plants. toledo, spain: arts graficas, 2004. [7] s. o. gnan and m. t. demello, "inhibition of staphyloccus aureus by aqueous goiaba extracts," journal of ethno pharmacology, vol. 7, pp. 112-117, 1999. [8] ticzon, ticzon herbal medicine encyclopedia. phillpines: romeo r. ticzon company publishing, 1997. [9] a. l. otsusi, a. foriers, a. vercrysee, and a. vanb zeebrock, "invitro antimicrobial activity of size medicinal plant traditionally used for the treatment of dysentery and diarrhea in democratic republic of congo (drc) phytomdeine," journal of phytomedicine, vol. 7, pp. 162-172, 2000. [10] f. r. irvine, woody plants of ghana. london: oxford university press, 1961. [11] h. usman, f. i. abdulrahman, and a. a. ladan, "phytochemical and antimicrobial evaluation of tribulus terrestris. l zygophylaceae) growing in nigeria res," j. of biosc. medwel j., vol. 2, pp. 244-247, 2007. [12] y. s. krivoshein, handbook on microbiology. russia: mic publisher, 1989. [13] g. e. trease and w. c. evans, pharmacognosy, 11th ed. london: baillier tirdal, 1978. [14] r. tschesche, advances in the chemistry of anti-biotres substances from higher plants; pharmacognosy international congress. heidelberg new york: verlog, berlin, 1971. [15] a. o. ogundaini, from greens into medicine taking a lead from nature inaugurad lecture series no.176. nigeria: o.a.u press ltd, ile-ife, 2005. [16] e. u. etuk, m. ugwah, n., o. p. ajagbonna, and p. a. onyeyili, "ethnobotonical survey and preliminary evaluation of medicinal plants with antidiarrhoea properties in sokoto, nigeria," journal of science forum, vol. 2, pp. 80-85, 2009. [17] p. k. mukherjee, j. b. r. s. das, palm, and p. m. saha, "antidirraheal evaluation of nelumbe nucifera rhizome extract," india j. pharmacol., vol. 22, pp. 262-268, 1995. [18] j. galvez, a. zarzuelo, m. e. crespo, m. d. lorente, m. a. ocete, and z. j. jmene, "antidiarroeal activity of evphobia extract and isolation of active flavonoid content," planta medica., vol. 59, pp. 333-336, 1993. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 2, no. 1, 9-22, 2015 http://www.asianonlinejournals.com/index.php/arees * corresponding author 9 groundwater vulnerability assessment using different overlay and index methods for quaternary aquifer of wadi el-tumilat, east delta, egypt gad, m. i. 1* --el-kammar, m. m. 2 --ismail, h. m. g. 3 1,3 hydrology division, desert research center, el-mataryah, cairo, egypt 2 geology department, faculty of science, cairo university, cairo, egypt abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group contents 1. introduction ............................................................................................................................................................................... 10 2. materials and methods ............................................................................................................................................................. 12 3. results and discussion .............................................................................................................................................................. 16 4. conclusion and recommendations .......................................................................................................................................... 21 references ...................................................................................................................................................................................... 21 contamination from rapid urban development, industrialization and agricultural sources increasingly threatens the groundwater resource in the shallow phreatic quaternary aquifer of the wadi el-tumilat (qawt), east delta, egypt. in this paper, fourteen environmental sensitive heavy metals and two minor elements (po4 - and no3 ) were checked by the chemical analysis of both 25 surface and groundwater samples at 2006. an assessment of the qawt intrinsic vulnerability was carried out in this paper based on god, prast and drastic methods. the calculated vulnerability indexes resulted from the three methods showed great differences due to the different criterions used. moreover, a weight modification was assumed to adequate the arid zone. the obtained qawt vulnerability maps showed the high extension of medium vulnerability zones. the high vulnerability zones occupied about 35% and 31% from applying prast and drastic methods respectively. the high vulnerability in these areas was mainly related to the low values of depth to water (less than 10 m), the high permeability of the soils (9 m/day) and the high permeability of the vadose zone materials (more than 11 m/day). the most suitable areas for new reclamation activity were located in the southern boundary of wadi el tumilat especially the strip south el mahsama drain by 5 km. these resulted maps may provide planners with tools for a preliminary selection of priority areas for different forms of sustainable development. keywords: hydrogeology, vulnerability assessment, wadi el-tumilat, god, prast, drastic methods. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2015, 2(1): 9-22 10 1. introduction the term “vulnerability of groundwater to contamination” was first used by margat [1]. vowinkel, et al. [2] defined vulnerability as sensitivity plus intensity, where intensity is a measure of the source of contamination. intrinsic vulnerability is controlled exclusively by geological structure and hydrogeological conditions, while specific vulnerability includes, besides the former parameters, consideration of the type of a contaminant and the character of a contamination source [3]. in this paper, due to the groundwater contamination in some plots of the quaternary aquifer of wadi el tumilat (qawt), a trial to assess the intrinsic groundwater vulnerability was carried out applying three different methods to delineate the less vulnerable areas suitable for new reclamation activities. 1.1. location of the studied area the qawt lies between latitudes 30 0 25 \ and 30 0 35 \ n and longitude 31 0 45 \ and 32 0 20 \ e. it is bounded on the nw by bahr el baqar drain, on the west by wadi el watan, on the east by suez canal and its attached lakes and on the south by cairo-shubrawit ridges with total area of magnitude 1500 km 2 (figu5r4e 1). it is characterized by desert climate, with arid, hot and rainless summer, and mild winter with low precipitation (22-40 mm/year). the evaporation rate is very high (6-12 mm/day). figure-1. location map of the infiltration tests, pumping tests and monitored wells in the qawt 1.2. geomorphological aspects in the literatures [4-7], wadi el tumilat represents a part of the eastern gravelly slopes fringing the nile delta and bears the structural affinity to the syrian arc system. the northern limit is defined by the well known buried nile branch "pelusaic" which extends in ne-sw direction and is represented by a semi flat plain called el salhia plain (figure 2). el timsah and bitter lakes represent the remnants of an old structural and topographic low land area called isthmus stretch along the eastern boundaries. the southern boundary of wadi el-tumilat is represented by umm gidam gravelly sand sheets in the form of low lying slopes. the southern boundary is determined by a series of structural ridges extend in an e-w trend. the foreland slopes of the southern structural ridges are dissected by few morphotectonic main drainage lines, mostly of nw-se trend with numerous dendritic tributaries (figure 2). 1.3. geological aspects the study area is built up of sedimentary rocks belonging to both tertiary and quaternary ages (figure 2) with thickness more than 1500 m (table 1) [5, 7-13]. tertiary rocks are exposed south of the study area and represented by eocene, oligocene, miocene and pliocene units (figure 2). middle and upper eocene rocks are formed of shallow marine fossiliferous chalky, dolomitic sandy and marlylimestones. oligocene rocks are exposed in the area between cairo and suez at gebel umm el ragm and gebel umm qamar. they are formed of continental sands and gravels as well as volcanic basalts with variable thickness ranging from 45m at gebel iwiebid to 100m at gebel el nassuri area. miocene rocks are composed of sandy limestone and sandy marls of shallow marine origin and are represented by el shatt formation and el hommath formation. pliocene rocks are exposed in the area northwest of cairo along the margins of the heliopolis basin. quaternary deposits have a wide distribution represented by old deltaic deposits which are composed of fluviatile coarse quartz sand, cherty flinty pebbles and igneous fragments with few occasional fossil wood remains and young aeolian deposits. the subsurface sedimentary succession is also built of tertiary and quaternary rocks, tertiary rocks include miocene sandy limestone water bearing formation and pliocene impermeable shale and clay beds. the regional structure of the study area is homoclinal having a low northward dip. this dip controls the thickness of some aquifers. it forms the foreland side of the ancient mediterranean geosyncline. normal faults are the most conspicuous structural elements affecting the landscape in this area, and are dominantly represented by ne-sw trend with downthrown side toward se and nw and nw-se trend with downthrown side toward ne direction. the vertical displacement along these faults ranges from few meters to hundred meters which led to an increase of the thickness of the quaternary water bearing formation by due 3 m/km towards northeast direction [13]. asian review of environmental and earth sciences, 2015, 2(1): 9-22 11 1.4. hydrogeological conditions the water bearing formations in the wadi el-tumilat area comprise the qawt, occupies the shallow zone and the miocene aquifer dominating the deeper part [14]. the qawt represents the main aquifer in the region and composed of fluviatile and fluviomarine graded sand and gravel with clay intercalations of limited extension (figure 3). the basal portion of this aquifer is formed of dark plastic clay. the quaternary deposits rest directly with unconformity surface on the miocene hard limestone as recognized in the north and south of wadi el-tumilat. its total thickness increases generally from south to north. it is mainly recharged by nile water from the river branches and canals. the miocene aquifer is dominated by clasticfacies in the southern part of the study area and overlain by about 200 m of quaternary deposits [15]. in belbies-el tell el kabier-el salhiyafluviatile plain, the miocene sediments are composed of alternating sandy limestone and clay lenses, loose quartz sand and marl. the aquifer is more clayey towards east. the cross-section along the qawt monitoring well line (figure 3) shows the general characteristics of the mode of groundwater occurrences. it is clear that, the clay intercalations are generally existed towards south and north. in the narrow strip adjacent to the ismailia canal, the depth to the groundwater is highly affected by the surface water running in the canal. port said mediterranean sea el-ismailia q q q q q cairo tv tv tv te te te to to to to to to te tn tn tn tntn tnto to tn 0 20 40 60 km scale 31 00 32 00 31 30 31 00 30 30 30 00 quaternary surfacial deposits sand dunes sabkhas tertiary eocene undifferentiated neogene extrusive rocks oligocene undifferentiated cretaceous q te tn to tv k k to legend el manzala lake port said mediterranean sea bitterlake el-ismailia cairo 0 20 40 60 km scale 31 00 32 00 31 30 31 00 30 30 30 00 legend el ankabia-iweibid structural plain bitter lakes and isthmus plain belbies-el tell el kabier-el salhiya plains (old deltaic plains) wadi el tumilat depression desert dry drainage lines suez gulf suez gulf figure-2. geomorphologic map (left map) and the compiled geological map after geological map of egypt, 1971(right map) of the east delta table-1. sedimentary succession in the study area figure-3. the cross-section along the qawt monitoring well line in ne-sw direction showing different water bearing formations (after gad [13]) the qawt and the miocene aquifers are hydraulically connected but in some places, they are separated by a semi-permeable layer which is highly controlled by deep-seated faults. these faults cause the saline groundwater of miocene aquifer to move upward along the fault planes and mixed with the groundwater of the qawt [13]. the groundwater in the qawt ranges from unconfined in the western part to semi-confined in the eastern part due to the presence of capped and underlying clay beds. the groundwater flow in the qawt is directed mainly from south to north in the southern part (miocene aquifer) with very low hydraulic gradient (≈ 2x10 -4 ). an opposite direction is recorded from north to south in the area lying south of ismailia canal (hydraulic gradient ≈ 4x 10 -4 ). along the main flood plain and down stream of wadi el age lithology approximate thickness (m) eocene chalky limestone, sand and clay 432 oligocene sand, gravel and basalt 264 miocene sandy limestone and clay 224 pliocene marine clay 192 pleistocene fine sand and gravelly calcareous sand 352 recent aoelian sand and silt 40 w.21 w.22 w.766 e.5 w.28 w.25 w.33 w.34 w.36 miocene aquifer quaternary aquifer el m an ai ef c an al el m ah sa m a dr ai n is m ai lia c an al w.24 -200 -160 -140 -120 -100 -80 -60 -40 100 80 60 40 0 20 -20 m sea level a a nesw fig. (3.10): hydrogeological cross section a-a` extending in ne-sw direction (modified after gad, 1995). water table el karnak lake sarabium lake ismailia canal el mahsama drain el mahsama lake el temsah lake 0 5 10 km scale 30 27 30 30 30 33 31 45 32 00 32 15 a a sand sand and gravel clay legend sea level water table asian review of environmental and earth sciences, 2015, 2(1): 9-22 12 el ismailia canal el mahsama drain el mahsama lake 0 5 10 km scale 30 30 30 27 30 33 32 00 32 7.5 32 15 unexposed area. area of aquifer depletion (negative values area) area of neutral quifer (zero value area) area of aquifer accretion (positive values area) legend fig. (3.23): resultant water table map at the study area (december 1992 december 2005). tumilat, an opposite direction is recorded from north to south (local flow) in the area lying south of ismailia canal (the hydraulic gradient is about 8 x 10 -4 ). the main groundwater recharging source is the ismailia canal while suez and el-manaief fresh water canals are additional sources. in the western and eastern parts of the qawt, a general trend of discharge in w-e direction is observed due to the intensive pumping of groundwater for reclamation projects at wadi el-mullak, el-manaief and sarabium occupying the central part (figure 4, ismail [16]). figure-4. water table map at dec. 2005 (left map) and water table fluctuation map during 1992-2005 (right map, ismail [16]) of the qawt the constructed water table fluctuation map over the period dec. 1992dec. 2005 reflects the wide change in the water table values during this interval (figure 4). this reflects the need for intrinsic rather than specific vulnerability assessment. on the contrary, the uncultivated flat areas in the central flood plain of the qawt reveal no changes in the groundwater storage. the most deteriorated areas are those lying in the northern lowlands of the qawt while the least deteriorated areas are located in the southeastern part of it. the main irrigation canals network (suez fresh water canal and el manaief canal), the main drainage network (el mahsama drain, el mahsamalake, el karnak lake, el manaief lake and sarabium lake) play a significant role in the groundwater pollution in the qawt based on its vulnerability. 2. materials and methods the materials used in this paper are collected through carrying out four field trips in qawt area during the period 2005-08 with the team work of the desert research center. these materials include collection of archival well data (discharge, distribution, operating systems,…etc.) beside carrying out both pumping and infiltration tests representing the different soils in the qawt. the four infiltration test are performed using the double ring method, as described by black [17] and the field data are analyzed according to philip [18] beside archival data of six tests carried out by gad [13] and two tests by afify [19] . complete chemical analyses of both 26 surface water and 28 selected groundwater samples are performed in the central lab of the desert research center during the year 200507 according to the methods adopted by the u.s geological survey, rainwater and thatcher [20]. in addition, the environmental sensitive heavy metals and minor elements including al, b, cd, co, cr, cu, fe, mn, mo, ni, pb, sr, v, zn, po4 and no3 are evaluated to clarify the industrial and agricultural pollution. moreover, the following maps are prepared: 2.1. depth to water map depth to water parameter represents the depth of the water table from the topographic surface and gives an idea of the minimum distance that a pollutant has to travel to reach the saturated zone. depth to water was computed based on the field data during 2005. the recorded depth to water in the selected wells was used in constructing the depth to water map. 2.2. net recharge map the weighted net recharge depends mainly on the constructed isohyetal map of the qawt based on the meteorological data of the period 1936-993. the computed net recharge values in the selected points are equal to the difference between precipitation plus return flow after irrigation minus the evapotranspiration. applying the number of points for each value (table 2), the weighted net recharge map is constructed. table-2. assessment of net recharge [21] net recharge (mm/year) no. of points 0 – 50 1 50 – 100 3 100 – 180 6 180 – 250 8 >250 9 2.3. aquifer media map aquifer media information is depicted from the three major maps (the diffusivity, lithology cover and aquifer thickness maps). the diffusivity values were resulted from dividing the transmissivity t and the storativity s (or specific yield sy in case of unconfined aquifer). the transmissivity t and the storativity s is estimated from the el ismailia canal el mahsama drain el mahsama lake 0 5 10 km scale 30 30 30 27 30 33 32 00 32 7.5 32 15 fig. (10): water table contour map of the selected groundwater samples (december, 2005). asian review of environmental and earth sciences, 2015, 2(1): 9-22 13 carried out five pumping tests and four recovery tests in addition to other eight tests from previous work. theis [22] type curve method, cooper and jacob [23] straight line method and theis recovery method are used in the analysis of these data. the weighted diffusivity map has been prepared by multiplying the diffusivity value (t/s) for every borehole by its aquifer saturated thickness and the output data were organized in gis format through which the successive weighed diffusivity at each well can be determined. repeating the same steps for the other two parameters, the weighted aquifer media map is obtained. 2.4. soil media map the soil media map is very important because it determines the overall protective effectiveness of the soil and rock covers above the shallow aquifers. it reflects the main properties of the soil zone as effective field capacity (efc), cation exchange capacity (cec) and electric conductivity of the soil (ec). the efc, cec and ec analyses resulted from the deep soil profile of the qawt sited in shata [24] (table 3) is used in developing the soil media map. table-3. the available data of soil parameters of the different soil profiles in the study area (after shata [24]) soil profile n. soil depth (m) efc cec ec soil texture 1 0 – 0.2 8 6.36 820 sand 0.2 – 0.5 22 43.46 95 loam 0.5 – 1 22 56.51 32 loam 2 0 – 0.1 8 1.34 1.5 sand 0.1– 0.35 8 6.85 4.5 sand 0.35 – 0.7 8 6.47 6 sand 0.7 – 1.5 8 1.63 5.5 sand 3 0 – 0.25 8 3.69 2.5 sand 0.25 – 0.35 8 4.29 16 sand 0.35 – 1 8 6.36 24.5 sand 4 0 – 0.15 8 7.66 7 loamy sand 0.15 – 0.45 8 4.89 8 sand 0.45 – 0.75 8 4.29 0.75 sand 0.75 – 2 8 3.69 0.45 sand 5 0 – 0.15 8 5.11 11 sand 0.15 – 0.6 8 4.89 16.5 sand 0.6 – 0.75 8 7.28 17.5 sand 0.75 – 1.5 8 4.24 18 sand 6 0 –0.72 8 2.07 0.95 sand 0.72 – 1.05 8 2.17 0.8 sand 1.05 – 1.2 8 43.48 0.6 loamy sand efc is effective field capacity, cec is cation exchange capacity and ec is electric conductivity of the soil 2.5. topography map it is represented by steepness percent. areas with steep slopes are less vulnerable to groundwater contamination. the digital elevation model map (90 m x 90 m dem-map) obtained from shuttle radar topography mission (srtm) is used in extracting the topographic feature of the qawt. accordingly, the dem-map is modeled on gis platform using gis software to define the slope of each cell. 2.6. impact of vadose zone map the impact of vadose zone involves two main parameters of the unsaturated zone, the thickness of clay lenses and the soil infiltration rate. the clay content is an important parameter for adsorption processes, and to a slightly lesser extent for cation exchange and biodegradation processes. the weighted clay lenses' thickness is developed as described by bodenkunde [25], (table 4). table-4. assessment of unconsolidated rocks (number of points = ru), by bodenkunde [25] type of unconsolidated rock ru = no. of points per meter bed thickness clay 500 loamy clay, slightly silty clay 400 slightly sandy clay 350 silty clay, clayey silty loam 320 clayey loam 300 very silty clay, sandy clay 270 very loamy silt 250 slightly clayey loam, clayey, silty loam 240 very clayey silt, silt loam 220 very sandy clay, sandy silty, loam, slightly sandy loam, loamy silt 200 sandy loam, slightly loamy silt 180 slightly loam, silt, sandy loamy silt,silt, slightly sandy loam. 160 continue asian review of environmental and earth sciences, 2015, 2(1): 9-22 14 in the other side, the methodological approach used in this paper is based on the vulnerability modeling techniques using a range of different methods [3, 21, 26-36]. unfortunately, no unified methodology of vulnerability assessment has been accepted in the qawt although the problem has been presented in several works [16, 37-40]. this may attribute to the complexity and variability of recharge and groundwater flow conditions in the hydrogeological medium. for this reason, when developing the current concept for the intrinsic groundwater vulnerability map of qawt, the authors based it not only on the use of concepts published abroad but also on their own experience. 2.7. intrinsic vulnerability methodology intrinsic vulnerability is assessed by the god, prast and drastic overlay and index methods. the first god method [27, 41] considers the susceptibility of the aquifer to the entry of contaminants from the topographic surface. the following variables are analyzed: groundwater occurrence (g), overall lithology of aquifer or aquitard (o) and depth to groundwater table (d). the d factor depends on aquifer recharge. the marked irrigation system irregularity, both flooding and drip irrigation, that is typical in qawt, requires defining a specific period when evaluating the vulnerability of the qawt to contamination. vulnerability should be analyzed for the situation of greatest risk of groundwater contamination, that is, one corresponding to a period of high levels of irrigation, favoring aquifer recharge and the transport of contaminant materials, goldscheider and popescu [42]. qawt recharge from return flow after irrigation and seepage from the surface water bodies produce a rise in the piezometric level and thus increased vulnerability, due to the reduced transit time between the entry of potential sources of contamination and their contact with the groundwater. according to vrba and zaporozec [3] and civita [43], the god method comprises a mapping overlay based on a factor-scoring system. the variables g, o and d are obtained from the field measurements and the different constructed maps. the super-position of these three information layers is performed within a geographic information system (gis), which is used to calculate the index and classes of vulnerability where the god index reads: god vulnerability index = rating for groundwater occurrence x rating for overlaying lithology (only in case of unconfined aquifers) x rating for depth to water ……………………………………………..………….1 figure-8. god overlay and index system of aquifer vulnerability assessment (after foster and hirata [41]) very clayey sand, clayey sand, loamy silty sand 140 sandy silty, very loamy sand 120 loamy sand, very silty sand 90 slightly clayey sand, silty sand, sandy clayey gravel 75 slightly loamy sand, sandy silty gravel 60 slightly silty send, slightly silty sand with gravel 50 sand 25 sand with gravel, sandy gravel 10 gravel, gravel and breccia 5 unconsolidated volcanic material 200 peat 400 sapropel 300 asian review of environmental and earth sciences, 2015, 2(1): 9-22 15 in addition, the second prast rating system [43] is another method for quick assessment of vulnerability using five parameters: protective effectiveness, net recharge, aquifer media, soil media and topography. the overall "pollution potential" or prast index pi is established by applying the following formula: pi = prxpw + rrxrw + arxaw + sr xsw + trxtw…………………................................………..2 where r is the rating value and w is the weight associated to each parameter. the ratings in prast model were assigned values between 1 and 10, while the weight of every factor had a fixed value which is listed in table 5. table-5. assigned weights for prast parameters. one of the most widely used groundwater vulnerability methods is the third chosen method; i.e., drastic [26] and developed by the united states environmental protection agency (us epa) [44] as a method for assessing groundwater pollution potential. in the drastic method specific criteria are assigned different degrees of importance on a scale 1 to 5 (table 6). these criteria including: depth to water level, effective infiltration, aquifer media, type of soil, topography, impact of vadose zone, and the hydraulic conductivity of aquifer. vulnerability drastic index di is the sum of the multiplication of variable rank and weight of individual criterion. for each mapping unit, it is calculated using the most important seven different hydrogeological parameters that affect the potential for groundwater pollution. it is computed as [45-51]: di = drxdw + rrxrw + arxar + srxsw + trxtw + irxiw + crxcw …………..3 where d is the depth to water, r is the net recharge, a is the aquifer media, s is the soil media, t is the topography, i is the impact of the vadose zone, c is the hydraulic conductivity, r is the rating value and w is the weight associated to each parameter. each parameter is assigned the same weight all over the qawt but different ratings, according to the hydrological, geological and hydrogeological conditions. the weight of three criterions (soil media s, vadose zone media i and topography t) is modified to adapt the physical conditions of the qawt. worth mention, the soil media (s) and the impact of the vadose zone media (i) of the qawt can be considered as one continuous layer of equal importance, and can thus be assigned an equal weight (5). also, the drastic criterion relative to the slope of topography is governed mainly by the prevailing irrigation practice in humid areas including mountainous, rugged and flat surfaces which is different in arid area like the qawt with flat lands or lands with gentile slope. it modified from weight of 1 to 2. table-6. rating and weight of criterion for drastic criterions with assigned weights (after aller, et al. [26]modified for the qawt) no criterion classes of criterion weight of criterion rank 1 depth to groundwater table >5 m 5 7 3.15 m 8 1.1 – 3 m 9 <1 m 10 2 net recharge (mm/year) 50-75 4 2 76-100 3 101-125 4 126-150 5 >150 6 3 lithology of aquifer sandy clay, loam, loam and sand 3 2 sandy loam, sands 3 sands, sandy loam 4 sands 6 sands, gravel 8 4 soil media loam 5 5 sandy loam 6 shrinking clay 7 peat 8 thin anthropogenic 9 absent 10 5 topography (slope) (%) 2.9-3.9 2 7.5 2.5-2.9 8 2.0-2.5 8.5 1.6-2.0 9 1.0-1.6 9.5 1.0-0.0 10 6 impact of vadose zone clay 5 2 silty loam 3 continue parameter weight protective effectiveness 8 net recharge 4 aquifer media 3 soil media 2 topography 1 asian review of environmental and earth sciences, 2015, 2(1): 9-22 16 loam 4 sands 6 sands, gravel 8 7 hydraulic conductivity of aquifer (m/day) < 9 3 1 9-11 2 12-28 4 29-40 6 41-80 8 3. results and discussion the results of the chemical analysis of the chosen groundwater samples of the qawt show that the salinity distribution map (figure 5) is well conformable with the water table map (figure 4), where salinity increases gradually with the hydraulic gradient and vice versa. also, the hypothetical salt assemblages change from north to south according to metasomatic processes. the effect of the evaporites in the eastern parts is more pronounced in the high salinity of their groundwater. chloride water type is the dominant and exists by 86%, while the bicarbonate water type represents 14% only. the gradual increase of salinity and the change of water type in the qawt reveal that, the groundwater has been subjected to physiochemical mixing processes during the beginning of the holocene periods, cation exchange and the mixing of nile water with locally infiltrated fossil water. figure-5. salinity distribution map in mg/l (left) and the hypothetical salt assemblages (right map, fatouh, et al. [52]) of the groundwater of the qawt the groundwater pollution is observed from the results of the chemical analysis of the 14 environmental sensitive heavy metals and two minor elements (table 7). both surface and groundwater are mostly polluted with b, sr, v, po4 - and no3 according to the world health organization standards for drinking water (who) [53] and egyptian health committee for drinking water standards (ehcw) [54] standards (table 7). the concentration of these pollutants exists in risky levels. the concentration of po4 - in the groundwater ranges from 0.097 to 53.23 mg/l while no3 concentration ranges from 5.17 to 83.65 mg/l (table 7 & figure 6). figure 6 shows that the northeastern part is more polluted than the southern part of the qawt. this may attribute to the shallow depth to water, flood irrigation system, over use of the fertilizers and bad drainage system characterizing to the northeastern cultivated lands. table-7.results of chemical analysis of the minor and trace elements in the surface and groundwater of the qawt (values in mg/l). bdl is below detection limit, and the sign * represents the median concentration [21]. element concentration range in surface water (mg/l) concentration range in ground water (mg/l) world health organization standards for drinking water (who) [53] (acceptable) egyptian health committee for drinking water standards (ehcw) [54] (permissible) al 0.1 0.4744 (bdl) 0.05 0.2 0.2 b 0.006 9.245 0.0607 3.369 1 no index cd (bdl) (bdl) co (bdl) (bdl) cr 0.004 0.0257 0.004 0.0308 0.01 0.1 * cu 0.02 0.0915 0.02 0.2293 1 1.5 fe 0.003 0.2524 0.003 0.509 0.3 1 mn 0.0149 0.0151 0.0062 0.2087 0.1 0.5 mo 0.01 0.1584 0.01 0.0646 0.05 0.5 * ni 0.006 0.0114 0.006 0.0114 0.01 0.04 * pb (bdl) (bdl) sr 0.4252 22.425 0.4136 7.925 0.11 * v 0.007 2.681 0.0438 0.4084 0.01 0.1 zn 0.001 0.2257 0.012 0.1551 5 15 phosphate 0.037 2.9 0.097 53.23 1 1 nitrate 0.115 58.222 5.17 83.65 10 10 asian review of environmental and earth sciences, 2015, 2(1): 9-22 17 figure-6. iso-po4 concentration map (left) and iso-no3 concentration map in mg/l (right) in the groundwater of the qawt at 2005 in addition, the calculated god vulnerability index ranges from 0.2 (low vulnerable) to 0.5 (moderate vulnerable) (table 8) while it ranges from 36 (low vulnerable) to 97 (very high) for prast index (table 9). the calculated drastic vulnerability index shows a range from 80 to 142 (table 10). as a general, these indexes do not provide absolute answers; they only differentiate highly vulnerable areas from less vulnerable areas. the nature of these models are additive. every parameter in the model has a fixed weight indicating the relative influence of the parameter in transporting contaminants to groundwater. the parameter rates are variable, which allows the user to calibrate the model to suit a given region. the vulnerability classes are defined according to the range of the obtained vulnerability index, taking into account a classification made by navulur and engel [55], but even the classification proposed by lobo ferreira and oliveira [56] will show the same vulnerability in the qawt. table-8. the estimated god index (gi) required for intrinsic vulnerability mapping of the qawt table-9. the estimated prast index (pi) required for intrinsic vulnerability mapping of the qawt w.n p r a s t pi w.n p r a s t pi w.n p r a s t pi 9 4 1 6 25 0 36 51 16 1 9 25 0 51 59 10 1 18 30 15 74 10 4 1 9 25 0 39 52 16 1 6 25 0 48 68 10 1 9 30 15 65 17 22 1 6 25 0 54 53 16 1 9 25 0 51 69 10 1 24 30 15 80 19 26 1 9 25 0 61 54 18 1 12 25 0 56 70 16 1 9 25 15 66 21 24 1 6 25 16 56 55 18 1 6 25 0 50 71 24 1 9 25 15 74 25 4 1 9 25 16 55 56 16 1 9 25 0 51 72 10 1 9 25 15 60 32 24 1 24 25 16 90 57 16 1 12 25 17 54 73 10 1 12 30 15 68 47 14 1 12 25 16 68 60 4 1 18 25 17 65 74 10 1 18 30 15 74 48 14 1 6 25 15 62 61 4 1 12 25 16 59 75 10 1 9 30 15 65 28 30 1 9 25 15 80 62 6 1 9 25 16 57 76 32 1 6 30 15 84 46 14 1 12 25 15 67 63 8 1 6 35 16 66 77 10 1 9 35 15 70 11 16 1 18 25 15 75 64 36 1 9 35 16 97 78 14 1 6 35 15 71 12 8 1 18 25 15 67 65 6 1 12 35 16 70 79 14 1 9 35 16 74 13 8 1 9 25 15 58 66 8 1 18 35 16 78 80 12 1 12 35 16 76 49 6 1 12 25 15 59 67 8 1 9 30 16 64 81 8 1 18 35 16 78 50 16 1 18 25 0 75 58 10 1 12 25 15 64 82 10 1 24 35 16 86 table-10. the estimated drastic index (di) required for intrinsic vulnerability mapping of the qawt w. n d r a s t i c di w. n d r a s t i c di 9 35 1 6 25 0 15 3 85 61 35 1 12 25 16 10 3 102 10 35 1 9 25 0 15 3 88 62 35 1 9 25 16 10 3 99 17 40 1 6 25 0 15 3 90 63 35 1 6 35 16 10 3 106 19 40 1 9 25 0 15 6 96 64 40 1 9 35 16 15 3 119 21 40 1 6 25 16 10 6 104 65 35 1 12 35 16 15 3 117 25 35 1 9 25 16 10 6 102 66 40 1 18 35 16 15 3 128 32 35 1 24 25 16 10 12 123 67 45 1 9 30 16 15 3 119 47 35 1 12 25 16 10 6 105 58 40 1 12 25 15 10 3 106 48 35 1 6 25 15 10 12 104 59 40 1 18 30 15 10 3 117 28 40 1 9 25 15 30 6 126 68 35 1 9 30 15 10 3 103 46 40 1 12 25 15 30 12 135 69 35 1 24 30 15 10 6 121 11 35 1 18 25 15 15 6 115 70 40 1 9 25 15 10 6 106 12 35 1 18 25 15 15 6 115 71 35 1 9 25 15 10 6 101 13 35 1 9 25 15 15 6 106 72 40 1 9 25 15 10 6 106 49 35 1 12 25 15 15 3 106 73 35 1 12 30 15 10 6 109 50 35 1 18 25 0 15 3 97 74 45 1 18 30 15 10 6 125 51 35 1 9 25 0 15 3 88 75 40 1 9 30 15 10 6 111 continue asian review of environmental and earth sciences, 2015, 2(1): 9-22 18 52 35 1 6 25 0 15 3 85 76 35 1 6 30 15 10 6 103 53 35 1 9 25 0 10 3 83 77 40 1 9 35 15 10 6 116 54 35 1 12 25 0 10 3 86 78 40 1 6 35 15 10 6 113 55 35 1 6 25 0 10 3 80 79 45 1 9 35 16 10 6 122 56 35 1 9 25 0 10 3 83 80 45 1 12 35 16 10 6 125 57 35 1 12 25 17 10 3 103 81 45 1 18 35 16 10 6 131 60 35 1 18 25 17 10 3 109 82 50 1 24 35 16 10 6 142 w.n is well number, d is the depth to water, r is the net recharge, a is the aquifer media, s is the soil media, t is the topography, i is the impact of the vadose zone, c is the hydraulic conductivity and di is the vulnerability drastic index. the effect of the hydrogeological conditions on the vulnerability assessment of the qawt is clear through the small differences between the produced intrinsic vulnerability maps applying the prast and drastic methods of overlay and index. the final intrinsic vulnerability maps obtained in this study show three classes of vulnerability in the qawt: low, medium and high (figure 7, 8 and 9). the resulted intrinsic vulnerability map of qawt applying god method (figure 7) indicates higher vulnerability in the area around el-mahsama lake and el-mahsama drain and clearly indicates the bad drainage system of this locality. the same results of high vulnerable areas of the qawt are obtained applying both prast and drastic models (figure 8 & 9). these two vulnerability maps reflect simplicity of aquifer vulnerability spatial distribution which is practically more or less not true. this may attribute to the selection of the ratings and weights that has to be assigned to the five or seven base maps which represent the five or seven parameters in case of prast or drastic model. such a selection can strongly affect the result of the final vulnerability map. given the fact that it is not possible to avoid subjectivity, the way to deal with it is by performing a sensitivity analysis which is out of scope of this study. figure-7. intrinsic vulnerability map according to god method figure-8. intrinsic vulnerability map according to prast method asian review of environmental and earth sciences, 2015, 2(1): 9-22 19 figure-9. intrinsic vulnerability map according to drastic method the obtained vulnerability maps by different methods show, in general terms, some sort of homogeneity in respect to overall zonation. in other words, the maps show two distinct zones, the northern zone which tends to attain comparatively high index values, and the southern zone which is characterized generally by the lowest index values. this is particular due mainly to the extreme difference between the northern and the southern zones in respect to depth to water, net rate of recharge, topography and presence or absence of agricultural lands where pesticides weights has to be taken into account. the northern zone is featured by lands of relatively low levels and accordingly the proximity of groundwater to the surface, in addition to intensive irrigation. the southern zone is characterized by higher topographic levels accompanied accordingly by deeper groundwater in addition to limited irrigation practice. therefore, it can be stated that the southern zone is less vulnerable than the northern zone. as a general, the obtained results related to the vulnerability show the high extension of the zones with medium vulnerability (21%, 65% and 61% for applying god, prast and drastic methods respectively) comparing to the other zones of the groundwater. the zones with high vulnerability occupy about 35% and 31% from applying prast and drastic methods respectively while the god method do not show any ratio for this class. the zones with low vulnerability occupy about 79%, 13% and 8% of the total surface of the groundwater in case of applying god, prast and drastic methods respectively. the zones with high vulnerability are located mainly in spots between el-qassasin and el-mahsama lake in the west and el-manaif village in the east. also, they cover great parts of abu sweir city (al-amal and al-mostaqbal new towns). the high vulnerability in these zones is mainly related to the low values of depth to water (less than 10 m), the high permeability of the soils (9 m/day) and the high permeability of the vadose zone materials (more than 11 m/day), which are mainly constituted by sandstone or by intercalations of sand and sandstone. the moderate vulnerability areas are locating in a vast zone located in the south, west and north of the ismailia town. other occurrence is related to the area of the village of nefisha, at the crossroads of the cairo-ismailia and suez-ismailia highways, and in the zone of sarabium. finally, the areas with low vulnerability are locating in the extreme south of the wadi el-tumilat, and in some restricted zones ne the 10 th of ramadan city and in the region of the el-wadi drain. however, these newly developed maps are found to be more or less in conformity with the salinity distribution map of the groundwater in the study area (figure 5), which shows high values of tds in the north and that the salinity decreases towards the south direction. also, the developed maps shows the presence of two infected centers with pollution (in the north and the south) which is comparable with the po4 -& no3 concentration contour maps (figure 6). finally, it is noticed that in general, in the qawt, the areas located adjacent to the ismailia canal and local drains crossing high vulnerable zones are characterized by a permeable vadose zone, and that can increase the risk of the pesticides' pollution and other pollutants in these areas. in the other point, if the newly developed drastic map is compared with the previous drastic maps prepared by rigw/iwaco [37] (figure 10) and by saad [39] (figure 11) and by the vulnerability map of dahab, et al. [40] (based on the classification scheme of zekster [57] (figure 12), some distinct variations are observed. whereas, the newly developed drastic map identifies spots of the northern portion of the qawt as highly vulnerable, and the southern portion attains low vulnerability, the other previous maps reveal opposite conclusions. this is, however, due mainly to the fact that the latter vulnerability mapping do not take into consideration some important factors (depth to water, net recharge and hydraulic conductivity). rigw/iwaco [37] drastic map neglects the soil media and hydraulic conductivity parameters while [37] drastic map divides the drastic parameters into static (five parameters) and dynamic (two parameters). dahab, et al. [40] vulnerability map neglects the depth to groundwater and the net recharge parameters. also, the rigw/iwaco [37] map has not given differentiation between the weights of the various factors involved in the aquifer vulnerability, and accordingly, all factors are given the same degree of importance. it can thus be concluded that the rigw/iwaco [37] map represents, to a great extent, the static features, of the aquifer vulnerability. accordingly, if the dynamic parameters are integrated to the rigw/iwaco [37] map the final aquifer vulnerability will approach the final drastic map presented in this paper. finally, these previous maps are considered as operative maps in the classification of civita [43]. asian review of environmental and earth sciences, 2015, 2(1): 9-22 20 figure-10. intrinsic vulnerability map according to drastic method (after rigw/iwaco [37] ) figure-11. intrinsic vulnerability map according to drastic method (after saad [39]) figure-12. intrinsic vulnerability map according to drastic method (after dahab, et al. [40]) asian review of environmental and earth sciences, 2015, 2(1): 9-22 21 4. conclusion and recommendations in this paper, the groundwater pollution of the qawt is detected from the results of the chemical analysis of both surface and groundwater samples collected at 2005. both surface and groundwater resources are mostly polluted with b, sr, v, po4 - and no3 with risky levels. the concentration of po4 - and no3 in the groundwater ranges from 0.097 to 53.23 and 5.17 to 83.65 ppm respectively. the northeastern part is more polluted than the southern part of the qawt due to shallow depth to water, flood irrigation system, over use of the fertilizers and bad drainage system. three different overlay and index methods (god, prast and drastic) have been used based on the hydrogeological conditions for vulnerability assessment. the calculated vulnerability indexes resulted from these three methods show greet differences due to the different criteria used. the calculated god vulnerability index ranges from 0.2 (low vulnerable) to 0.5 (moderate vulnerable) while it ranges from 36 (low vulnerable) to 97 (very high vulnerable) for prast index, and from 80 (low vulnerable) to 142 (very high vulnerable) for drastic index. these indexes only differentiated highly vulnerable areas from less vulnerable areas. also, a modification from weight of 1 to 2 for the drastic criterion relative to the slope of topography is assumed to adequate the hydrogeological conditions of arid zones like the qawt. the obtained results related to the vulnerability maps show the high extension of the zones with medium vulnerability (21%, 65% and 61% for applying god, prast and drastic method respectively) comparing to the other zones of the groundwater. the zones with high vulnerability occupy about 35% for the prast overlay method and 31% for the drastic overlay method while the god method do not show any ratio for this class. the zones with low vulnerability occupy about 79% for the god overlay method, 13% and 8% of the total surface of the groundwater in case of applying prast and drastic overlay methods. the zones with high vulnerability are located mainly in spots between el-qassasin and el-mahsama lake in the west and el-manaif village in the east. also, they cover great parts of el-manaif village in the east and abu sweir city (al-amal and al-mostaqbal new towns). the high vulnerability in these zones is mainly related to the low values of depth to water (less than 10 m), the high soil permeability (9 m/day) and the high permeability of the vadose zone materials (more than 11 m/day). the developed intrinsic vulnerability maps show the presence of two infected centers with pollution (in the north and the south) which are comparable with the po4 -& no3 concentration contour maps. the newly developed drastic map is more or less comparable with the previous drastic maps cited in rigw/iwaco [37] and saad [39] and the vulnerability map in dahab, et al. [40]. some distinct variations are observed due mainly to both the fact that the latter vulnerability mapping do not use some important factors like depth to water, net recharge and hydraulic conductivity, and equalization between the weights of the various factors involved in preparing these aquifer vulnerability maps. based on the results of this paper, it is recommended that the most suitable areas for new reclamation activity locate in the southern boundary of wadi el tumilat especially the strip south el mahsama drain by 5 km. it is also highly recommended to make public awareness about the threats of pollution on groundwater resources especially in the vulnerable areas. sealing the drainage system to minimize the pollution by heavy and trace elements in the northern and eastern lowlands is highly recommended. improving the irrigation system and preventing the continuous drainage of sewage and waste water to ismailia canal and the drainage system is also recommended. the continuous use of the huge garbage dumps, especially near sarabium area and the ismailia-suez desert road characterized by shallow groundwater must be transported to other suitable places. references [1] j. margat, vulnerabilite des nappes d'eau souterraine a la pollution: brgm publication 68 sgl 198 hyd, orleans.guideline for groundwater vulnerability mapping doc, 1968. [2] e. f. vowinkel, r. m. clawges, d. e. buxton, d. a. stedfast, and j. b. louis, "vulnerability of public drinking water supplies in new jersey to pesticides," u.s. geological survey, fact sheet fs-165-96. reston/usa, p. 3, 1996. [3] j. vrba and a. zaporozec, "guidebook on mapping groundwater vulnerability, international association of hydrogeologists (iah)," international contribution to hydrogeology, v. 16, hannover: heise verlag, 1994. [4] a. a. shata, "geological structure of the nile delta," journ. of engin. cairo, (in arabic), pp. 1-3, 1965. [5] i. f. el fayoumy, "geology of groundwater supplies in the region east of the nile delta," unpublished ph. d. thesis, fac. sci., cairo univ, 1968. [6] a. a. shata and i. f. el fayoumy, "remarks on the regional geological structure of the nile delta," symposium hydrology of delta, unesco, vol. 1, pp. 189-197, 1970. [7] e. m. el shazly, m. a. abdel hady, m. m. el shazly, m. a. el ghawabby, i. a. el kassas, a. b. salman, and m. a. morsi, "geological and groundwater potential studies of el ismailia master plan study area," remote sensing research project, academy of scientific research and technology, cairo, egypt, 1975. [8] m. e. el diasty, "the aeromagnetic map of the delta area and the interpretation of the geophysical data," unpublished m. sc. thesis, fac. sc., alex. univ., egypt, 1969. [9] s. a. ahmed, "the geology of the desert east of cairo," bull. inst. desert, egypt, vol. 111, pp. 42-89, 1977. [10] m. d. el dairy, "hydrogeological studies on the eastern part of nile delta using isotope techniques," unpublished m. sc. thesis, fac. of sc., zagazig univ, 1980. [11] m. el ahwani, "geological and sedimentological studies of gabal shabrawet area, suez canal district, egypt," ann. geol. surv. cairo., vol. 12, pp. 305-381, 1982. [12] e. a. korany, e. h. shendi, and s. abdel tawab, "integrated detection of the problem of groundwater over-flow in abu zaabal basalt quarries, egypt," e. g. s. proc. of 11th ann. meet, 1993. [13] m. m. gad, "hydrogeological studies for groundwater reservoirs, east of the tenth of ramadan city and vicinities," unpublished m. sc. thesis, ain shams univ, 1995. [14] i. z. el shamy and m. h. geriesh, "hydrogeology of west ismailia area, egypt," desert inst. bull., egypt, vol. 42, pp. 271-288, 1991. [15] z. el shamy, "hydrogeology of wadi el tumilat and surroundings, east of the nile delta, egypt," 8th symp. phaner. develop., egypt, 1992. [16] h. m. g. ismail, "study the vulnerability of groundwater aquifer for pollution in wadi el-tumilat, eastern delta," unpublished m.sc. thesis, fac. of sci., cairo univ, 2008. [17] c. a. black, methods of soil analysis. madison: am. soc., agron. inc. pub, 1973. [18] j. r. philip, "the thory of infiltration. 1. the infiltration equation and its solution," soil sci., vol. 83, pp. 345-457, 1957. asian review of environmental and earth sciences, 2015, 2(1): 9-22 22 [19] h. f. afify, "studies on the municipal contamination of water resources in some villages of ismailia governorate, egypt," unpublished ph. d. thesis, suez canal univ., egypt, 2004. [20] f. r. rainwater and l. l. thatcher, "methods for collection and analysis of water samples, v.s.g.s. water supply, paper no. 1454," p. 301, 1960. [21] b. holting, t. haertle, k. h. hohberger, k. h. nachtigal, e. villinger, w. weinzierll, and j. p. wrobel, "konzept zur ermittlung der schutzfunktion der grundwasseruberdeckung," geol. jahrbuch, reihe c, heft 63, hannover, 1995. [22] c. v. theis, "the relation between the lowering of the piezometer surface and the rate and duration of discharge of well using groundwater storage," am. geophys. union trans., vol. 16, pp. 512-524, 1935. [23] h. h. cooper and c. e. jacob, "a generalized graphical method for evaluating formation constants and summarizing well field history," am. geophys. union trans, vol. 27, pp. 526-534, 1946. [24] a. a. shata, "genesis, formation and classification of the soils south ismaelya canal between belbeis and ismaelya including wadi el-tumilat," m. sc. thesis, fac. agricul., zagazig univ, 1978. [25] a. bodenkunde, bodenkundliche kartieranleitung, 4th ed. hannover, germany: schweizerbart publ, 1994. [26] l. aller, t. bennett, j. h. lehr, r. j. petty, and g. hackett, "drastic: a standardized system for evaluating ground water pollution potential using hydrogeological settings," epa reports, 600/2-87-035, washington dc, usa, 1987. [27] s. s. d. foster, "fundamental concepts in aquifer vulnerability, pollution risk and protection strategy," vulnerability of soil and groundwater to pollutants; 38 (van duijvenboden & h.g. van waegeningh eds.), tno commission on hydro res, proc. and inform., hague, 1987, pp. 69–86. [28] n. robins, b. adams, s. foster, and r. palmer, "groundwater vulnerability mapping: the british perspective," hydrogeologie, vol. 3, pp. 35–42, 1994. [29] s. s. d. foster, groundwater recharge and pollution vulnerability of british aquifers – a critical overview. london, uk: geological society special publication, 13, 1997. [30] n. doerfliger, p. y. jeannin, and f. zwahlen, "water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and gis tools (epik method)," environmental geology, vol. 39, pp. 165–176, 1999. [31] s. hannapel and h. j. voight, "vulnerability maps as a tool for groundwater protection – case studies from eastern germany," hydrogeology and land use management (m. fendekova & m. fendek eds.), proc. xxix congress iah bratislava, 1999, pp. 59– 64. [32] r. c. gogu and a. dassargues, "current trends and future challenges in groundwater vulnerability assessment using overlay and index methods," environmental geology, vol. 39, pp. 549–559, 2000. [33] t. al zabet, "evaluation of aquifer vulnerability to contamination potential using the drastic method," environmental geol., vol. 43, pp. 203-208, 2002. [34] d. daly, a. dassargues, d. drew, s. dunne, n. goldscheider, s. neale, i. c. popescu, and f. zwahlen, "main concepts of the european approach to karst-groundwater-vulnerability assessment and mapping," hydrogeology journal, vol. 10, pp. 340–345, 2002. [35] s. foster, r. hirata, d. gomes, m. d’elia, and m. paris, groundwater quality protection. a guide for water utilities, municipal authorities and environment agencies. washington, dc: the world bank, 2002. [36] a. zurek, s. witczak, and r. duda, "vulnerability assessment in fissured aquifers. in: groundwater quality and vulnerability," prace wydzialu nauko ziemi, 22, (rubin, rubin & witkowski eds.), univ. of silesia, sosnowiec (in polish), 2002. [37] rigw/iwaco, vulnerability of groundwater to pollution. cairo, egypt, 1990. [38] rigw, "groundwater potential in the nile valley and delta," internal report. cairo, egypt, 1991. [39] a. k. f. saad, "environmental hydrogeologic impacts of groundwater withdrawal in the eastern nile delta region with emphasis on ground-water pollution potential," unpublished ph.d thesis, institute for environmental studies and research, ain shams univ, 1998. [40] k. a. dahab, e. a. el abd, m. k. fattah, and m. m. el osta, "assessment of groundwater problems of the quaternary aquifer in the area between el salhyia el gidida-abu sweir, east nile delta, egypt," grmena ii, vol. 2007, pp. 329-353, 2007. [41] s. s. d. foster and r. a. hirata, groundwater pollution risk assessment–a methodology using available data. lima, peru: whopaho-cepis publication, 1988. [42] n. goldscheider and c. popescu, the european approach. in: zwahlen f (ed) vulnerability and risk mapping for the protection of carbonate (karst) aquifers. brussels: european commission, 2004. [43] m. civita, le carte della vulnerabilita degli acquiferi all inquinamento: teoria e pratica. bologna, italy: pitagora editrice, 1994. [44] united states environmental protection agency (us epa), "przm-2, a model for predicting pesticide fate in the crop root and unsaturated soil zones: user manual for release 2.0. u.s. environmental protection agency, epa 600/r-93/045," p. 406, 1993. [45] l. aller, t. bennett, j. h. lehr, and r. j. petty, "drastic standardized system for evaluation groundwater pollution using hydrogeologic settings," u.s. epa robert s., kerr environmental research laboratory, oklahoma, epa/600/2-85, 1985. [46] d. s. durnford, k. r. thompson, d. a. ellerbrook, j. c. loftis, and g. s. davies, "screening methods for ground water pollution potential from pesticide use in colorado agriculture," colorado water resources research institute, completion report no. 157. fort collins, 1990. [47] j. p. lobo ferreira and m. m. oliveira, "drastic ground water vulnerability mapping of portugal," proceedings from the 27th congress of the international association for hydraulic research, san francisco, usa, aug. 10-15, 1997, pp. 132-137. [48] s. d. lynch, a. g. reynders, and r. e. schulze, "a drastic approach to ground water vulnerability in south africa," south african journal of science, vol. 93, pp. 59-60, 1997. [49] m. melloul and m. collin, "a proposed index for aquifer water-quality assessment, the case of israel's sharon region," journal of environmental management, vol. 54, pp. 131-142, 1998. [50] y. j. kim and s. hamm, "assessment of the potential for ground water contamination using the drastic/egis technique, cheongju area, south korea," hydrogeology journal, vol. 7, pp. 227-235, 1999. [51] s. lyakhloufi, s. er-rouane, n. ouazzani, and a. el habil, "vulnerabilite et rique de pollution de la nappe phreatique du haouz de marrakech," hydrogeologie, orleans, vol. 3, pp. 43-52, 1999. [52] e. m. fatouh, m. i. gad, a. a. abdel-baki, and m. a. awad, "water resources characteristics between 10th of ramadan city and suez canal area, egypt," proceedings of the 6th int. engineering conference fac., of eng.-mansoura univ., mansoura/sharm elsheikh march 2008 20-23, 2008, pp. 290-301. [53] world health organization standards for drinking water (who), international standards for drinking water, 3rd ed. vol. 1. geneva, switzerland, 1984. [54] egyptian health committee for drinking water standards (ehcw), "ير عاي م ة ال صري م ياه ال م شرب ل عمال ال ت س ي واال نزل م ال ون قان ل قال ب م ط نة 27 رق س ي 1978 ل شأن ف يم نظ موارد ت عامة ال ياه ال لم .1995 ",ل [55] k. c. s. navulur and b. engel, "predicting spatial distributions of vulnerability of indiana state aquifer system to nitrate leaching using gis." available: http://www.ncgia.ucsb.edu/conf/santa_fe_cd-rom/sfpapers/navulurkumar/my_paper.html, 1997. [56] j. p. lobo ferreira and m. m. oliveira, "on the experience of groundwater vulnerability assessment in portugal," aquifer vulnerability and risk international workshop avr03, salamanca gto. mexico, 2003. [57] i. s. zekster, groundwater and the environment. london, new york: lewis publishers, 2000. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. http://www.ncgia.ucsb.edu/conf/santa_fe_cd-rom/sfpapers/navulurkumar/my_paper.html, asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 2, 30-34, 2014 http://www.asianonlinejournals.com/index.php/arees 30 water quality assessment of kampani river, plateau state, nigeria r. a. lawal 1 --y. n. lohdip 2 --j. n. egila 3 1,2,3 department of chemistry, university of jos, plateau state, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction the increasing concentration of heavy metal in the biosphere is of great concern to the scientist all over to world. heavy metals are found naturally and thus cannot be destroyed in soils, sediment or water by any chemical or biological means. they pose major environmental and human health problem due to their great ecological significance, toxicity and accumulative behavior [1, 2]. heavy metals such as lead, iron, manganese, nickel, arsenic, zinc, copper, cobalt, mercury, chromium, cyanide, bismuth, antimony are considered as conservative pollutants [3] and thus are disastrous to human health. other sources of heavy metal contamination are through atmospheric deposition and erosion of geological matrix, and through anthropogenic means by industrial effluent discharges from tanneries, breweries, textiles, potteries, electroplating, metal finishing, mining, dyeing, printing, ceramic, photographic industries as well as smelting, fossil fuel combustion and from agrochemical industries [4, 5] [6]. their poisonous nature makes them the leading cause of death and diseases and accounts for the death of more than 14,000 people daily [7, 8]. the most recent in nigeria, is the zamfara lead poisoning that led to the dead of over 400 children in 2010 [9]. heavy metals are known to cause diseases such as convulsion in small children, lung cancer, liver cancer, kidney disease, brain damage, respiratory tract infection, and poor vision among others [10, 11]. mining, as one of the major anthropogenic sources of heavy metal in water [5, 12] has received so much attention due to its great health implication which is easily transferred through food chain. the greater damage of mining activity is witnessed in the localities as the case in wase l.g.a., where tribute workers engaged in the manual as well as modern mining of minerals which could lead to indiscriminate disposal of some toxic substances such as heavy metals on land and in the aquatic system. this is hazardous since majority of the miners are ignorant of the consequences. the harmful effect of mining activity can only be known by measuring the concentration and distribution of heavy metals as well as other contaminants in water. a lot of work on environmental monitoring has been reported in the southern and eastern part of nigeria. however there is little information regarding the quality of water in the middle belt, particularly in the south eastern part of the plateau state. this work aimed at assessing the levels of heavy metal pollution in water due to mining activity in kampani river. this will go a long way in protecting the lives of people and animals particularly those exposed to the dangerous effect of this activity. 2.1. study area kampani river is situated in wase local government area, south eastern part of plateau state, nigeria. it is about 292.8km from the state capital. this river empties into river benue, one of the major rivers in nigeria. the paper assessed the physico-chemical and heavy metal levels of surface water collected from kampani river, wase local government area of plateau state. the analysis was done using standard procedures. the mean annual concentrations of the metals studied ranged from 0.320.45mg/l for cr; 0.110.27mg/l for cu; 0.33 – 0.45mg/l for co; 0.05 – 0.91mg/l for cd; 14.96 – 20.68mg/l for fe; 1.01 – 5.30mg/l for mn; 0.09 – 0.22mg/l for ni; 0.80 – 1.68mg/l for pb and 1.15–1.63mg/l for zn. the physico-chemical analysis revealed the following range of values 7.45 – 7.49 for ph; 27.86 – 103 µs/cm for electrical conductivity; 18.82 – 20.76 ntu for turbidity; total hardness,109.51 – 291.68mg/l; alkalinity, 0.08 – 28.33mg/l; chloride, 11.32 – 43.43mg/l and tds,74.21 – 152.59mg/l. most of the metals analysed showed significantly higher concentrations which follow the order fe>zn>mn>cd>pb>co>cr>cu>ni during the dry season and fe> mn> pb >zn>cr>co>cu>ni >cd in the wet season. comparing with who , nis and son standards guidelines, the results revealed that the consumption of water from river kampani could be disastrous to human health. keywords: heavy metal, pollution, assessment, kampani river, mining, plateau state. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(2): 30-34 31 fig-1. map of nigeria showing the plateau state fig-2. map of plateau state showing the wase l.g.a. 2.2. sample collection sampling was done during dry season between the month of march – april 2012 and september – october 2012 in the wet season. samples were collected at five different points within a particular sampling station and at 1 km intervals between the sampling stations and along the plain of the river. grab samples were collected in a 2l plastic container which were prewashed with detergent, then with nitric acid solutions, rinsed with distilled water and finally with the water source. the samples collected were preserved at 4 o c before the analysis. those for heavy metal determination were preserved by adding three drops of nitric acid at the field [13, 14]. 3. experimental the water temperature was measured on site with a glass mercury thermometer. the conductivity was determined using a hanna potable conductivity metre. and ph was measured with digital ph metre. colour asian review of environmental and earth sciences, 2014, 1(2): 30-34 32 determination was done using lovibond comparator while turbidity was analysed by absorbance method [10]. alkalinity, total hardness and chloride were determined by titrimetric method. total dissolved solid was done by gravimetric method while metallic elements were analysed using atomic absorption spectrophotometric method. 4. results and discussion tables 1,2,3,4 and 5 show the results for the physicochemical analysis and metallic elements contents of water samples from kampani river. from table 1, the mean temperature of the river for dry and wet seasons ranged between 24.2 – 26.6oc respectively. the temperature of the water appears to be high in the wet season (26.6oc). this reflected the air temperature of the eastern part of the state. the results of the ph measurement revealed that the water is slightly alkaline in both seasons 7.47 – 7.45.this may be due the presence of carbonates of calcium and magnesium [15]. the electrical conductivity values were low 27.86 – 103.0 µs/cm and were all within the who and son standards [16]. the mean concentrations of chlorides in the water were in the range 11.3 – 43.4 mg/l with high values in the wet season. this can be attributed to the effect of rainfall on rocks. the results of the total hardness showed that the wet season values 291.687mg/l were higher than that obtained in the dry season, 109.51mg/l. this could be due to runoff which washes away the mine wastes and rocks and deposit into the river. the alkalinity value of the water was higher than that obtained in the dry season while tds showed high values only in the wet season and were all within the standard limit .the high value of tds could be due to the effect of rain and other dissolve salts in the river [17] . the river water was highly turbid with the annual mean concentration between 18.8mg/l – 20.8mg/l. this is above the standard set by who, son and nis (table 3). chlorides values were observed to be in the range of 11.3 – 43.4mg/l with higher concentrations observed in the wet season. heavy metals analysis showed high values of chromium 0.32 – 0.48mg/l; cadmium 0.05 – 0.9 mg/l and iron 14.96 – 20.20.68mg/l. the values of manganese ranged between 1.01 – 5.3mg/l; nickel 0.09 – 0.22 mg/l and lead 0.8 – 1.68mg/l. the highest values of chromium, cobalt, iron and lead were found in the wet season while that of copper, cadmium and zinc showed high concentrations in the dry season (table 2 and 3). all the metals examined were above the acceptable limits set by who for drinking water except for copper and zinc which were low. the concentrations of heavy metals in the water during the dry season was in the order fe>zn>mn>cd>pb>co>cr>cu>ni and fe>mn>pb >zn>cr>co>cu>ni >cd in the wet season. table 4 and 5 revealed that there is strong correlation between most of the metals which indicate same source. since kampani is not an industrial area, the high concentrations of these metals can be traced to the mining activity going on in the area for decades and the natural deposit of these metals in the earth crust. the use of charger batteries, fertilizer application on farm land especially those close to the river, as well the use of pesticides in fishing could also be another contributing factor. 4.1. statistical analysis the results obtained were subjected to statistical analysis such as correlation matrix. the correlation coefficient matrix of the parameters determined is presented in tables 4 and 5. the correlation coefficient of 0.5 was taken as significant. 5. conclusion the examination of water quality parameters in kampani river revealed that the water contain high level of toxic metals such as chromium, lead, cadmium, manganese, cobalt and nickel which are capable of causing diseases such as cancer, kidney damage, liver problem, neurological disorder and hepatitis among others. the values exceeded the limit set by who, nis and son for drinking water. so the river is therefore, said to be polluted. moreover, the river requires urgent attention in order to prevent heavy metal poisoning. table-1. physico-chemical parameters of water samples from kampani river sample location temp (oc) ph e.c (µs/cm) colour (hz) turbidity (ntu) t.harness (mg/l) t.alkalinity (mg/l) chloride (mg/l) tds (mg/l) dry season: point 1 26.oo ± 0.71 7.45 ±0.26 25.00 ±0.00 6.00 ±0.00 20.83 ±8.05 97.50 ±0.50 29.11 ±1.02 8.74 ±3.25 37.50 ± 2.21 point 2 27.00 ±0.58 7.44 ±0.12 30.00 ±0.00 6.00 ±0.00 32.70 ±5.15 113.53 ±2.16 27.63 ±1.14 13.58 ±3.77 44.98 ±6.00 point 3 26.50 ±0.58 7.39 ±0.31 30.00 ±0.00 6.00 ±0.00 22.00 ±1.41 117.33 ±1.16 28.34 ±1.02 13.03 ±1.96 44.98h ±1.61 point 4 26.75 ±0.96 7.18 ±0.11 26.25 ±1.6 6.00 ±0.00 7.53 ±0.74 109.6 ±3.51 28.25 ±4.53 9.94 ±4.75 39.37 ±3.74 wet season: point 1 24.00 ±0.41 7.65 ± 0.06 118.00 ±4.47 6.40 0.00 43.57 31.39 289.64 ±13.02 .07 ±0.01 27.69 ±7.92 176.93 ±6.67 point 2 24.00 ±0.00 785,00 ±0.05 6.40 ±5.00 13.00 ±0.00 287.55 ±0.07 0.07 ±8.63 54.67 ±0.04 115.48 ±17.04 ±14.42 point 3 24.00 ±0.00 7.34 ±0.11 115.00 ±5.77 6.4 ±0.00 11.10 ±1,23 295.64 ±12.67 0.09 ±0.01 51.12 ±12.50 176.98 ±9.59 point 4 24.00 ±0.48 7.40 ±0.02 94.00 ± 4.80 6.4 ±0.00 7.61 ±1.31 2 93.88 ±6.50 0.09 ±0.003 40.23 ±6.31 140.99 ±7.20 asian review of environmental and earth sciences, 2014, 1(2): 30-34 33 table-2. heavy metal content of water samples from kampani river sample elements locations cr cu co cd fe mn ni pb zn dry season : point 1 0.34 0.11 0.22 2.23 11.06 0.34 0.22 1.01 1.96 point 2 0.29 0.14 0.28 0.07 16.40 2.14 0.11 0.52 0.99 point 3 0.38 0.11 0.55 0.92 14.12 1.17 0.35 0.59 2.14 point 4 0.28 0.73 0.71 0.40 18.26 0.39 0.21 1.10 1.41 wet season: point 1 0.45 0.14 0.44 0.06 17.70 4.80 0.09 1.52 0.96 point 2 0.49 0.10 0.36 0.03 14.86 4.65 0.07 1.45 1.00 point 3 0.42 0.08 0.40 0.05 26.11 5.23 0.10 1.31 1.48 point 4 0.54 0.10 0.59 0.06 24.07 6.90 0.12 2.44 1.17 table-3. seasonal variation of heavy metal content of water from kampani river table-4. correlation coefficient matrix of water sample for dry season asian review of environmental and earth sciences, 2014, 1(2): 30-34 34 table-5. correlation matrix of heavy metals from kampani river for wet season references [1] m. n. v. prascal and h. m. o. frectas, "metal hyperaccumulation in plantsbiodiversity prospectting for phytoremediation technology," electronic journal of biotechnology, vol. 6, pp. 285-321, 2003. [2] m. ozturk, g. ozozen, o. minareci, and minarei, "determination of heavy metals in fish, water and sediments of avsar dam lake in turkey," iranian journal of environmental health science, vol. 6, pp. 73-80, 2009. [3] u. u. egereonu, l. n. ukiwe, and j. c. egereonu, "investigation of pollution index of surface and ground water of ndibe river catchment, afrikpo, nigeria," journal of chemical society of nigeria, vol. 37, pp. 27-31, 2012. [4] m. a. atieh, "removal of zinc for water using modified and non-modified carbon nanofibres," presented at the 2nd international conferences on environmental sciences and technology, singapore, 2011. [5] i. s. eneji and r. sha’ato, "onecycle seasonal variation of heavy metals convcentration in river benue," journal of chemical society of nigeria, vol. 37, pp. 102-107, 2012. [6] j. c. igwe, a. a. abia, and e. d. asuquo, "studies on the influence of counter ions and modification of adsorbent on the kinetics of hg (ii), as (ii), and pb (ii) ions removal from aqueos solutions using sawdust meal," journal of chemical society of nigeria, vol. 37, pp. 77-79, 2012. [7] l. west, "world water day. a billion people worldwide," lack safe drinking water, 2006. [8] w. e. mangset, t. okeke, and d. i. jwanbot, "determination of gross alpha and beta radioactivity in mining ponds from barkin ladi local government area plateau state," african journal of natural sciences, vol. 12, pp. 61-66, 2009. [9] y. n. lohdip, inaugural lecture on the insolvency of the universal solvent: that all may have enough to drink vol. 52: university of jos inauguaral lecture series, 2011. [10] m. l. kagoro, j. j. gongden, and r. a. lawal, "water quality assessment: the josjarawa case," journal of science, engineering and technology, vol. 14, pp. 9900-9908, 2011. [11] h. c. maduka, "water pollution and man’s healtgh," the internet journal of gastroenterology, vol. 4, 2005. [12] e. o. okorie and j. n. egila, "distribution of metals in an abandoned coal mine overburden soil from okaba, kogi state, nigeria," journal of chemical society of nigeria, vol. 37, pp. 41-53, 2012. [13] f. e. okiemen, e. c. duru, and d. i. olorunfemi, "comparative evaluation of physicochemical and microbiological characteristics of ballast water samples from three oceanic vessels," journal of chemical society of nigeria, vol. 37, pp. 87-92, 2012. [14] r. a. lawal and y. n. lohdip, "physicochemical and microbial analysis of water from mimyak river in kanke l.g.a. of plateau state, nigeria," african journal of natural sciences, vol. 14, 2011. [15] a. begum, s. harikrisha, and i. khan, "analysis of heavy metals in water," sediment and fish from madivala lakes of bangalore, karnataka, vol. 1, pp. 245-249, 2009. [16] world health organisation, guiglines for drinking water quality, 4th ed. ceneva, switzerland, 2011. [17] s. h. o. egboh and e. m. emeshili, "physicochemical characteristics of river ethiope source in umuaja, delta state, nigeria," journal of chemical society of nigeria, vol. 32, pp. 72-76, 2007. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences vol. 4, no. 1, 7-11, 2017 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2017.41.7.11 7 dynamics in times of ionizing radiation and rainfalls in tropical region of brazil inacio m. martin1  douglas c. vilela2 marcelo p. gomes3 ( corresponding author) 1,2,3technological institute of aeronautics, ita, sp, brazil abstract low energy gamma rays and rainfalls were monitored each minute in the region around são josé dos campos, (230:10`s, 450:53`w) in brazil, from march 7th to june 28th in 2017. in this period, it was possible to see the dynamic process that occurs between the presence of ionizing radiation (gamma rays) of low energy and the variation of rain intensity in (mm) / min in the same region. during this period, 12 major peaks of radiation intensity corresponding to 12 rains of high and low intensities were observed. this positive rainfall / radiation correlation is very noticeable in the tropical region of brazil, which is certainly due to the presence of the decay of 238u uranium into radium 226ra and arriving at the 222rn radon with α emission particles and low energy gamma radiation. therefore, the rain interferes in the presence of the local exhalation of the radon gas, causing the washing of this gas in the low atmosphere, increasing the intensity of radiation measured momentarily in that location. this work shows this dynamic measured in this interval in the year 2017, where there was rainy and dry weather in the place. keywords: gamma ray, ionizing radiation, rainfall analysis, tropical regions citation | inacio m. martin; douglas c. vilela; marcelo p. gomes (2017). dynamics in times of ionizing radiation and rainfalls in tropical region of brazil. asian review of environmental and earth sciences, 4(1): 7-11. history: received: 29 june 2017 revised: 18 july 2017 accepted: 21 july 2017 published: 26 july 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: thanks cnpq (national counsel of technological and scientific development) and capes (coordination for the improvement of higher education personnel) by the fellowships grants support to the group's researchers. the ita division of fundamental sciences for supporting this research. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 8 2. materials and methods ...................................................................................................................................................................... 8 3. results and discussions ..................................................................................................................................................................... 8 4. conclusion ......................................................................................................................................................................................... 10 references .............................................................................................................................................................................................. 10 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=inacio m. martin https://orcid.org/orcid-search/quick-search?searchquery=douglas c. vilela https://orcid.org/orcid-search/quick-search?searchquery=marcelo p. gomes https://orcid.org/orcid-search/quick-search?searchquery=inacio m. martin https://orcid.org/orcid-search/quick-search?searchquery=douglas c. vilela https://orcid.org/orcid-search/quick-search?searchquery=marcelo p. gomes https://orcid.org/orcid-search/quick-search?searchquery=inacio m. martin https://orcid.org/orcid-search/quick-search?searchquery=douglas c. vilela https://orcid.org/orcid-search/quick-search?searchquery=marcelo p. gomes https://orcid.org/orcid-search/quick-search?searchquery=inacio m. martin https://orcid.org/orcid-search/quick-search?searchquery=douglas c. vilela https://orcid.org/orcid-search/quick-search?searchquery=marcelo p. gomes asian review of environmental and earth sciences, 2017, 4(1): 7-11 8 1. introduction in the ground level interface of the earth's surface, ionizing radiation is mainly comprised of radon gas, the telluric radiation from the ground and the primary and secondary cosmic ray radiation. however, it is difficult to separate over time the intensity of ionizing radiation emanating from each component as the energies overlap. the telluric radiation is composed of 238u, 235u, 40k, 232th chains and is constant for each region [1]. radon gas comes from the 238u decay of the earth's crust [2] to ra-226 and rn-222 arriving in isotopes 214pb, 214po and 214bi giving α and gamma radiation. the primary cosmic radiation mainly consists of galactic and extragalactic protons from the sun with very high energy, which interact on the earth's atmosphere producing the eas (extensive air showers) [3]. the efficiency of this interaction is maximal when it occurs at altitudes between 15 and 17 km in the tropics, forming secondary cosmic rays with muonic, mesonic, and neutronic components that propagate to the earth's surface in the region [4]. these radiations cause health problems for the crew and passengers of civil aviation and are present at the beginning of the stratosphere called maximum pfotzer. however, this component contributes less to radiation concentration on the earth's surface. another possible existing ionizing radiation source in the lower atmosphere of the earth is produced by electrical discharges between clouds-earth-ground and clouds-clouds. x-rays, gamma rays, neutrons and beta particles are formed all the way of the lightning cone [5]. other ionizing radiation sources are those produced in medical, dental clinics and hospitals, but these radiations are mostly controlled in small areas. 2. materials and methods the gamma ray detector for the energy interval of 200 kev to 10.0 mev consists of a scintillating crystal of sodium iodide 3 inches high by 3 inches in diameter (3” x 3”), doped with thallium. this crystal is coupled directly to a photomultiplier (pm), which registers the pulses coming from the scintillator and with amplification and an analog-to-digital converter that is registered by a computer [6]. this experimental set is seen in figure 1 located in a room inside a tower 25 meters high in relation to the ground. in that tower and with all radiation detectors and meteorological apparatus is running the project atmosrad – ionizing radiation in low atmosphere – since 2009. this project have grants each year from ita and national brazilian research council (cnpq). figure-1. view of the gamma scintillator with associated electronics and computer source: project atmosrad 2017 the scintillator coupled with a photomultiplier is wrapped in a thin layer of aluminum to make it portable. the set (scintillator + associated electronics + data acquisition) depends only on a laptop with fully charged battery to measure radiation up to 10 hours straight. however, for series of longer measurements, electrical grid or photovoltaic energy is used. the scintillator and associated electronics were calibrated in terms of energy and intensity of counts per minute at the ita experimental physics teaching laboratory using radioactive sources and a spectrum analyzer of counts versus energy in the interval of 0,2 to 10 mev (millions of eléctron volts) [7, 8]. 3. results and discussions measurements were performed between march 7th, 2017 to june 28th, 2017 at the same location shown in figure 1, at the 25-meters high iae tower [7]. the interval between each measurement was set at 1 minute. therefore, it was possible to verify periods of rain and the dynamic of ionizing radiation in the region. figure 2 shows, during this period, 12 rains shown by the peaks of radiation increase, caused by these rains. figure-2. measurements of gamma radiation in the interval of 0.2 to 10.0 mev (millions of electron volts), each minute between march 7th and june 28th of 2017. source: project atmosrad 2017 asian review of environmental and earth sciences, 2017, 4(1): 7-11 9 examining figure 2, there is moderate rainfall between 43 to 43.5 x 103 minutes from the beginning of the monitoring of the radiation series. the expansion of the graph in this region shows the detail of the occurrence of rainfall via measurement of ionizing radiation (gamma rays) in this range, as shown by figure 3. figure-3. monitoring of rainfall through gamma radiation in the interval between 43 to 43.5 x 103 minutes after the start of the measurements. source: project atmosrad 2017 note this monitoring of radiation in figure 4 shows a zoom close to the interval of 72000 minutes after the start of the measurements, where a cold front passes through the region culminating in an intense rain caused by this cold front. during five days, there was a small increase of local gamma radiation, leading to an intense rain at the end of these five days. this established meteorological dynamic is widely observed in the region in this period of time between five and seven days provoking rains and cloud coverings less or more intense. the transformation between dose of radiation µsv/h is related to bq/m3 of the radon gas through the gamma formula [8]: ( / ) 0.3857 0.000866 ( / ³)gy h radon bq m   , so if it is measured a dose in time the amount of radon gas in bq/m3 can be estimated. figure-4. interval of radiation monitoring in which there was rain between 72.0 to 72.5 x 103 minutes. source: project atmosrad 2017 during the period of 129.5 to 130.5 x 103 minutes, there were intermittent rains varying in intensity, see figure 5. figure-5. intermittent rains varying in intensity, between 129.5 to 130.5 x 103 minutes. source: project atmosrad 2017 asian review of environmental and earth sciences, 2017, 4(1): 7-11 10 another moderate rainfall that altered the intensity of measured gamma radiation can be observed at ~ 141 x 103 minutes after the start of monitoring, as shown in figure 6. before this rain, the local temperature rose to 300 degrees celsius in the day before the rain due to the arrival of a cold front coming from southern brazil. figure-6. moderate rainfall in the time of ~ 141,000 minutes of monitoring. source: project atmosrad 2017 analyzing the dynamics of gamma radiation, measured from minute to minute as a function of time, at a fixed location, one can also observe the dynamics of the variation of rainfall occurring in the same place. figure 7 shows the rainfall spectrum as a function of time measured in the same period and in the same place always with a oneminute interval between each measurement performed. figure-7. spectrum as a function of time of rains occurred every minute between march 7th and june 28th of 2017. source: project atmosrad 2017 it is noted that the time around 43 x 103 minutes in figure 7 corresponds to a moderate rain, observed in figure 3, of radiation. between 72 to 73 x 103 minutes, there is an intense rain, shown in figure 7, corresponding to the increase of radiation seen in figure 4. figure 7 (intensity of rainfall in the period) can be carefully correlated with figure 2 (intensity of gamma radiation in the period). therefore, in the tropical region of brazil due to the exhalation of radon gas it is possible to correlate intensity of radiation measured with local rainfall intensity presence. 4. conclusion in this work, using a simple gamma ray detector in the energy interval of 0.2 to 10.0 mev, it was possible to correlate radiation measurements with rainfall measurements of the region carried out in the period of march 7th to june 28th of 2017. this positive rainfall / radiation correlation is very noticeable in the tropical region of brazil which is certainly due to the presence of the decay of the uranium 238u into radium 226ra and decaying into radon gas 222rn with the emission of α particles and low energy gamma radiation. having calibrated between water intensity and the intensity of gamma radiation at this location, it is possible to measure the intensity of rainfall by monitoring the gamma radiation in the region. another work is being done in order to show this calibration with tests carried out in the ita laboratory [9]. references [1] v. n. a. bui, i. m. martin, and a. t. júnior, "measurements of natural radioactivity at different atmospheric depths," ciencia e cultura. suplemento, vol. 40, pp. 407, 1988. view at google scholar [2] n. fujinami, "study of radon progeny distribution and radiation dose rate in the atmosphere," japan journal health physics, vol. 44, pp. 89-94, 2009. view at google scholar | view at publisher [3] p. k. f. grieder, extensive air showers. berlin heidelberg: book springer:verlag, 2010. [4] v. s. malyshevsky and g. v. fomin, "electromagnetic radiation in the atmosphere generated by excess negative charge in a nuclear-electromagnetic cascade, nasa astrophysics data system (ads)." retrieved from https://www.science.gov/topicpages/e/electromagnetic+cascade+shower.html. [accessed 06/07/2017], 2017. https://scholar.google.com/scholar?hl=en&q=measurements%20of%20natural%20radioactivity%20at%20different%20atmospheric%20depths https://scholar.google.com/scholar?hl=en&q=study%20of%20radon%20progeny%20distribution%20and%20radiation%20dose%20rate%20in%20the%20atmosphere http://dx.doi.org/10.5453/jhps.44.89 http://www.science.gov/topicpages/e/electromagnetic+cascade+shower.html asian review of environmental and earth sciences, 2017, 4(1): 7-11 11 [5] u. b. jayanthi, a. a. gusev, j. a. c. f. neri, t. villela, o. p. júnior, g. i. pugacheva, k. c. talavera, and i. m. martin, "ground gamma radiation associated with lightning and rain precipitation," presented at the 29th i, cosmic ray conference, 2005. [6] r. ravisankar, k. vanasundari, a. chandrasekaran, a. rajalakshmi, m. suganya, p. vijayagopal, and v. meenakshisundaram, "measurement of natural radioactivity in building materials of namakkal, tamil nadu, india using gamma-ray spectrometry," applied radiation and isotopes, vol. 70, pp. 699-704, 2012. view at google scholar | view at publisher [7] b. j. boardman, "aware electronic corp." retrieved from www.aw-el.com, 2015. [8] s. s. nigam, "assessment of radon and gamma in taboshar mining site," tajikistan, master of science thesis. norwegian university of life science, department of plants science, 2012. [9] c. s. matheus, c. v. douglas, m. g. victor, g. p. marcelo, m. m. inácio, and g. j. silvério, "ionizing radiation measurements using low cost instruments for teaching in college or high-school in brazil submitted to physics education." retrieved from http://iopscience.iop.org/journal/0031-9120. [accessed may 2017], 2017. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=measurement%20of%20natural%20radioactivity%20in%20building%20materials%20of%20namakkal,%20tamil%20nadu,%20india%20using%20gamma-ray%20spectrometry http://dx.doi.org/10.1016/j.apradiso.2011.12.001 http://www.aw-el.com,/ http://iopscience.iop.org/journal/0031-9120 22 asian review of environmental and earth sciences vol. 5, no. 1, 22-26, 2018 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.22.26 the effect of long term irrigation by treated effluent on boron accumulation in soil and citrus plants ra'fat abu daba'an1 husam al-najar2  ( corresponding author) 1,2civil and environmental engineering department, islamic university of gaza. gaza strip, palestine abstract the aim of the current research is to assess the long term effect of boron concentration in treated wastewater on citrus plants cultivated in various soil textures. boron concentrations of treated wastewater used in sandy and clay soil were 1.45±0.37 and 1.03±0.45 mg/l, respectively. in sandy soil, boron concentrations were 0.53 ± 0.15 and 3.94 ± 0.97 mg/ kg soil showed significant variation at p < 0.05 between the top 030 and the second layer 3060 cm, respectively, while the leaves of citrus have boron concentration of 104.1 mg/kg dry weight. in clay soil boron concentrations were 0.79 mg/kg in both soil layers and in citrus leaves was 267.1 mg/kg dry weight which slightly exceeds the recommended limits 250 mg/kg dry weight. therefore, the fate of boron depends mainly on the soil texture; in the sandy soil leaching to deeper layers is occurred, while boron is accumulated in clay soil and citrus leaves. thus, the municipal treated wastewater could be used safely to irrigate citrus cultivated in sandy soil textures. keywords: boron, citrus, desalination, gaza strip, treated effluent. citation | ra'fat abu daba'an; husam al-najar (2018). the effect of long term irrigation by treated effluent on boron accumulation in soil and citrus plants. asian review of environmental and earth sciences, 5(1): 22-26. history: received: 12 july 2018 revised: 15 august 2018 accepted: 21 september 2018 published: 29 october 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: both authors contributed to the conception and design of the study. funding: the authors would like to thank the middle east desalination research center (medrc) and palestinian water authority (pwa) who kindly financialize the research project. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 23 2. study area and methodology ........................................................................................................................................................ 23 3. results and discussion ................................................................................................................................................................... 23 references .............................................................................................................................................................................................. 26 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.22.26&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/706 https://orcid.org/0000-0001-8777-4663 http://asianonlinejournals.com/index.php/arees/article/view/706 https://orcid.org/0000-0001-8777-4663 http://asianonlinejournals.com/index.php/arees/article/view/706 https://orcid.org/0000-0001-8777-4663 asian review of environmental and earth sciences, 2018, 5(1): 22-26 23 1. introduction water consumption in the gaza strip is increasing continuously due to population increase resulting from natural growth, while the available water resources are decreasing due to urban development and increase of runoff which negatively affected the groundwater recharge [1-3]. the gaza strip is located in a semi-arid region categorized as sever water shortage area. the recharge of the groundwater from rainfall is insufficient to cover the demand, leading to imbalance in groundwater where seawater intrusion occurred deteriorating the groundwater quality [4]. total up flow from groundwater beneath the gaza strip exceed 200 mm3 per year [5]. virtually two third of groundwater pumped by 10000 wells used for agriculture propose, causing around 110 mm3 annual deficit of water balance. therefore, it is important to preserve potable groundwater for domestic use and to reuse the treated effluent for irrigation constituting an additional renewable and trustworthy water resource [6, 7]. the maximum quantity of treated effluent expected to reach 92 mcm per year by 2020 [8] may be used for irrigation of all irrigated areas cultivated with citrus, olives and other fruit trees. gaza groundwater wells contain high concentrations of boron and this was clear after performing boron tests on some wells covering different regions. the tests showed that many water wells contains boron with concentration > 1.2 mg/l, while wastewater contains boron concentration up to 4 mg/l [9]. not all crops are equally sensitive to boron; some plants can show boron deficiency at a concentration that would be toxic to a different plant. boron at levels greater than 0.30.5 mg/l in irrigation water found to be toxic for citrus plants [10-12]. due to the proposed strategic plan of the palestinian water authority (pwa), which mainly depends on the seawater desalinated for domestic supply, the first desalination stage can remove boron to 1.8 mg/l to suite the who regulation for drinking purposes. boron concentration will increase massively in the wastewater and will lead to a boron problem specially it would harm the corps which will be irrigated by the treated wastewater. therefore, the levels of boron toxicity in citrus as a most sensitive plant among the common plants in the gaza strip will be investigated based on boron concentration and soil texture to answer the question whether more stages are required for boron removal to reuse the treated effluent for irrigation. 2. study area and methodology in 2004, the job creation program (jcp) in cooperation with palestinian hydrologists group has proposed a project to use treated effluent from sheikh ejleen wastewater treatment plant for irrigating of 100 dunums (1 dunum = 1000 m2) of citrus planted in clay soil. the project has been established under french fund and the supervision of palestinian water authority (pwa) and municipality of gaza with coordination with ministry of health (moh) and ministry of agriculture in parallel, with a fund of the catalan government, the jcp in close cooperation with pwa and coastal municipal water utility (cmwu), launched a small pilot project 60 dunums for reuse of treated effluent. the irrigation system is a drip irrigation system in sandy soil planted with citrus. 2.1. sampling of treated effluent, soil and citrus leaves 48 soil samples from each site were collected from the fields at two different depths (030 cm) and (3060 cm). samples were collected from leaves of citrus from 20 different trees in each site in addition to 10 samples were collected from irrigation water from each pilot project, nitric acid (hno3) was added to samples stored in polyethylene containers to meet quality standard precautions 2.2. soil extraction the following steps describes the boron extraction method by hot water according to university of georgia modified procedure from bercer and truog [13]; gupta [14]. 1. weigh of 10 g air-dried, 2-mm sieved soil into 100 ml plastic flasks. 2. 50 ml deionized water added to the soil sample. 3. the flasks incubated in hot water shaking bath for 30 minutes at 80oc. 4. to remove the extract from the soil, the samples are filtered by 150-mm diameter filter paper into 100 ml plastic flasks. 5. the filtration process is repeated to obtain clear supernatant for boron extract measurement. 2.3. boron determination boron in the treated effluent, soil and plant leaves extracts were determined using atomic emission spectroscopy by inductively coupled plasma (icp-aes). the instrument was manufactured by spectro genesis company that has a detection limit of 1.25 μg /l. 3. results and discussion 3.1. boron concentration of treated effluent as previously described in the study area, samples from two location were collected from the irrigation water, soil and plant tissue. as shown in figure 1, the treated effluent has boron concentration of 1.03 ± 0.45 and 1.45 ± 0.37 mg/l from the clay and sandy soil sites, respectively. the high boron concentration in the treated effluent at both sites refers to the boron concentration in the groundwater which accounted for 1.13 and 1.03 mg/l at clay and sandy soil locations, respectively. referring to vengosh, et al. [15] study prepared to investigate the source of boron in the southern mediterranean coastal aquifer including gaza coastal aquifer (figure 2), boron concentration in the groundwater is higher than 1 mg/l which is the limitation of who for drinking water. moreover, the study proved that the main source of boron is the rocks of the aquifer [9, 15]. it is worth to mention that the treated effluent has higher boron concentration than the groundwater due to the added boron from detergents and domestic uses. asian review of environmental and earth sciences, 2018, 5(1): 22-26 24 figure-1. boron concentration in the treated effluent that used in irrigation in clay and sandy soils boron concentration in irrigation water is classified to three categories in terms of its effect to the plants, none, moderate and sever. israel, saudi arabia, japan and states like california and florida have quite strict guidelines of extreme boron concentrations ranging from 0.4 to 1 mg/l for irrigation purposes [16]. in canada a guideline for irrigation water ranging from 0.5 – 6 mg/l according to crop sensitivity for boron [17] whereas groundwater and the treated effluent mostly higher than 1mg/l in the gaza strip. figure-2. distribution of boron concentrations in the gaza strip wells, eu and who restricted limits [15] 3.2. boron accumulation in the soil as shown in figure 3, samples from various depths 030 and 3060 cm were collected from clay soil site showed insignificant differences in both soil layers at p < 0.05. boron concentrations accounted for 0.79 ± 0.24 and 0.78 ± 0.30 mg/kg soil, respectively. in sandy soil, the results showed significant variation at p < 0.05 between the top 030 cm layer and the second layer 3060 cm. boron concentration accounted for 0.53 ± 0.15 and 3.94 ± 0.97 mg/ kg soil, respectively. the sandy soil leached boron to the lower layers, while this was not seen in clay soil site. boron from irrigation water like most of the minerals can accumulate in the soils but it has higher affinity than other minerals. in soils, boron may be found in four forms: organically bound, soluble in soil water, adsorbed in soil surface, and fixed at clay minerals. arid, saline soils generally contain the highest boron concentration. in sandy soils, boron is leached more readily than in clay soils and is thus less likely to accumulate to toxic concentrations. the canadian environmental quality (ccme) guidelines suggest guideline of 2 mg/kg soil boron [17]. this soil guideline is based on the protection of plants as the most sensitive receptor to boron, which is consistent with irrigation water being among the most restrictive of the water quality guidelines. asian review of environmental and earth sciences, 2018, 5(1): 22-26 25 figure-3. boron concentration in 0-30 and 30-60 cm layers of clay and sandy soils 3.3. boron in the leaves of citrus boron concentration in the leaves of citrus planted in clay soil accounted for 267.08 ± 15.35 mg/ kg dry matter. significant lower concentration at p < 0.05 is detected from citrus leaves planted in sandy soil and accounted for 104.10 ± 9.54 mg/ kg dry matter (figure 4). the difference in the concentration refers to the different soil texture, the sandy soil leaching of boron to deep soil layers is tested in comparison to clay soil. in general boron concentration in plants irrigated by treated effluent has high concentration, but it is far down toxicity threshold in most cases. however, there is a danger for reaching toxicity threshold in the case of long term irrigation for citrus in clay soil because of high accumulation of boron in leaves of citrus cultivated in clay soil reach to 267 mg b/kg dm that exceeded the toxicity threshold 250-260 mg b/kg dm [18]. figure-4. boron concentration in the leaves of citrus cultivated in clay and sandy soil the high boron concentration in the leaves of citrus at clay soil site in comparison with the leaves boron concentration at sandy soil site is due to the variation of the soil ph at both sites and the leaching of boron from the sandy soil (figure 3). the soil ph is 8.18 and 7.8 in clay and sandy soil, respectively. boron bioavailability is reduced at moderately high ph values of 7.5-8.5 [19]. the probability of boron uptake due to high ph may be partially offset by the excess of boron present in treated effluent. both soil layers at clay soil site has ec ranges from 1.49 and 1.77 ds/m. while at sandy soil site the top layer ec equals 4.51, while the lower layer has 10.56 ds/m. leaching of salts is emphasized in the sandy soil by the increased soil salinity at lower layers, while this was not clear at clay soil. use of treated effluent has significant prospective as a continued source of supplementary irrigation water, growing affectedly in water deficit regions like the middle east and north africa. due to its climate similarity, citrus is the most commonly cultivated crop which is suitable to be irrigated with treated effluent because of the acceptable distance between the fruit and irrigation water networks. this minimize the contamination with microorganisms. more concern should be given to the effluent quality form inorganic standpoint such as boron sensitive crop. citrus in southern florida was irrigated with 0.31 mg b/l treated effluent for more than 10 years [20]. leading to annual increase of 4.6 mg b/kg dry weigh in leaves, but leaf concentrations still less than the toxic levels. nevertheless, if the same irrigation water with 0.31 mg b/l still in use for 30 years, leaf b concentrations will reach the harmful level (200 mg b/kg). the main constrains of long term use of treated effluent are salinity and boron concentration in most of the reuse studies. for instance in murcia, spain, treated effluent with 1.4 and 221 mg/l boron and chloride concentrations are limiting values for long term reuse in case of lemon irrigation [18, 21]. the installation of reverse osmosis plant in eilat produces potable water with boron concentration suite the asian review of environmental and earth sciences, 2018, 5(1): 22-26 26 domestic use, but farmers who used the treated effluent for irrigation observed discolored leaves of citrus due to the relatively high boron concentration levels for irrigation purposes [22]. in conclusion soil texture has abundant evidence in retain boron in the soil. boron concentration of both soil layer at clay site is 0.78 mg/ kg soil when irrigated by treated effluent of 1.13 mg/l. while the top layer 0-30 cm at sandy site is much lower boron concentration than the deeper layer 30-60 cm and accounted for 0.5 and 3.9 mg/ kg soil when irrigated by treated effluent of 1.03 mg b/l, respectively. the sandy soil leached boron to the lower layers, thus unlikely to accumulate to toxic concentrations in citrus. the concentration of boron in citrus planted in sandy soil is less than the planted in clay soil and accounted for 104 and 267 mg/kg dry weight, respectively. references [1] s. m. hamdan, u. troeger, and a. nassar, "stormwater availability in the gaza strip, palestine," international journal of environment and health, vol. 1, pp. 580-594, 2007.available at: https://doi.org/10.1504/ijenvh.2007.018582. [2] k. qahman, a. larabi, d. ouazar, n. ahmed, and h.-d. c. alexander, "optimal extraction of groundwater in gaza coastal aquifer," journal of water resource and protection, vol. 1, pp. 249-259, 2009.available at: https://doi.org/10.4236/jwarp.2009.14030. [3] h. al-najar, "the integration of fao-cropwat model and gis techniques for estimating irrigation water requirement and its application in the gaza strip," natural resources, vol. 2, pp. 146-154, 2011.available at: https://doi.org/10.4236/nr.2011.23020. [4] m. jarboo and h. al-najar, "climate change and its impact on domestic water consumption in sub-urban regions in the gaza strip," international journal of climate change strategies and management, vol. 7, pp. 3-16, 2015.available at: https://doi.org/10.1108/ijccsm-07-2013-0092. [5] palestinian water authority pwa, evaluation of water resources in the five governorates of gaza strip: water resources planning directorate, 2015. pwa library. gaza, gaza strip: water resources planning directorate, 2015. [6] h. al-najar, urban agriculture and eco-sanitation: the strategic potential toward poverty alleviation in the gaza strip. london: rics research, 2007. [7] coastal municipalities water utility cmwu, annual report on water status in the gaza strip. summary about water and wastewater situation in gaza strip. gaza, palestinian2016. [8] palestinian water authority pwa, water resources and management. gaza, palestinian: water resources and planning department, 2014. [9] a. s. ouda, "investigate the boron content reduction from seawater reverse osmosis permeate by ion exchange method (case study: swro desalination plant of gaza power station)," master thesis. civil engineering department. islamic universitygaza. gaza , palestine, 2014. [10] who (world health organization), safe abortion: technical and policy guidance for health systems, 2nd ed. geneva: geneva, 2003. [11] m. m. shaaban, "role of boron in plant nutrition and human health," american journal of plant physiology, vol. 5, pp. 224-240, 2010.available at: https://doi.org/10.3923/ajpp.2010.224.240. [12] c. m. grieve, s. r. grattan, and e. v. maas, "plant salt tolerance," agricultural salinity assessment and management, vol. 2, pp. 405459, 2012. [13] k. bercer and e. truog, "boron determination in soils and plants using the quinalizarin reaction," industrial and engineering chemistry. analytical edition, vol. 11, pp. 540-545, 1939. [14] u. c. gupta, "a simplified method for determining hot-watersoluble boron in podzol soils," soil science, vol. 103, pp. 424-428, 1967.available at: https://doi.org/10.1097/00010694-196706000-00009. [15] a. vengosh, w. kloppmann, a. marei, y. livshitz, a. gutierrez, m. banna, c. guerrot, i. pankratov, and h. raanan, "sources of salinity and boron in the gaza strip: natural contaminant flow in the southern mediterranean coastal aquifer," water resources research, vol. 41, pp. w01013-1, 2005.available at: https://doi.org/10.1029/2004wr003344. [16] p.-k. park, s. lee, j.-s. cho, and j.-h. kim, "full-scale simulation of seawater reverse osmosis desalination processes for boron removal: effect of membrane fouling," water research, vol. 46, pp. 3796-3804, 2012.available at: https://doi.org/10.1016/j.watres.2012.04.021. [17] alberta environment and sustainable resource development (aesrd), alberta tier 1 soil and groundwater remediation guidelines. alberta, canada: land and forestry policy branch, policy division, 2014a. [18] s. grattan, f. diaz, f. pedrero, and g. vivaldi, "assessing the suitability of saline wastewaters for irrigation of citrus spp: emphasis on boron and specific-ion interactions," agricultural water management, vol. 157, pp. 48-58, 2015.available at: https://doi.org/10.1016/j.agwat.2015.01.002. [19] r. o. nable, g. s. bañuelos, and j. g. paull, "boron toxicity," plant and soil, vol. 193, pp. 181-198, 1997.available at: https://doi.org/10.1007/978-94-011-5580-9_12. [20] b. pereira, z. he, p. stoffella, and a. melfi, "reclaimed wastewater: effects on citrus nutrition," agricultural water management, vol. 98, pp. 1828-1833, 2011.available at: https://doi.org/10.1016/j.agwat.2011.06.009. [21] f. pedrero and j. j. alarcón, "effects of treated wastewater irrigation on lemon trees," desalination, vol. 246, pp. 631-639, 2009.available at: https://doi.org/10.1016/j.desal.2008.07.017. [22] c. fritzmann, j. löwenberg, t. wintgens, and t. melin, "state-of-the-art of reverse osmosis desalination," desalination, vol. 216, pp. 1-76, 2007.available at: https://doi.org/10.1016/j.desal.2006.12.009. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences issn: 2313-8173 vol. 3, no. 1, 10-17, 2016 http://www.asianonlinejournals.com/index.php/arees 10 radiation protection measures in radio-diagnostic centers in gaza hospitals, palestine samer s. abu zer1 samir s. yassin2 mohamed r. al agha3 khalid jamal khadoura4  1 radiology department, shifa hospital, gaza strip, palestine occupied. 2 physics department, the islamic university of gaza. 3 environment and earth science department, the islamic university of gaza. 4 head nurse of internal medicine dep., shifa hospital, faculty of nursing, the islamic university of gaza, palestine. ( corresponding author) abstract whereas radio-diagnostic centers have potential to present hazardous effects due of ionizing radiation. radio-diagnostic workers awareness, practices regarding radiation protection issues, availability of radiation protection devices and effective personal radiation exposure monitoring process has an important role to safe working in these places. we carried out this study in nine governmental gaza governorates hospitals. the study instrument was close-ended structured questionnaire consists of five parts. 182 radio-diagnostic workers participated in the work. based on the obtained data, the participants reported that 35.2% of personal radiation protection devices are available in the radio-diagnostic centers at governmental gaza governorates hospitals. in spite the fact that 74.8% of participants have awareness about radiation protection issues, but it is only about 53.4% of participants follows the radiation protection practices. there is an obvious poor of personal radiation exposure monitoring process. conclusively, the results represented in this work reflect that majority of participants believe there is no radiation safety officer to provide the service. therefore, there is a desperate need for rules, regulations and radiation protection act in the field of radiation in medical field. keywords: radiation protection, radio-diagnostic, awareness, practices. contents 1. introduction ......................................................................................................................................................................... 11 2. objectives ............................................................................................................................................................................. 11 3. materials and methods ........................................................................................................................................................ 11 4. results and discussion ......................................................................................................................................................... 11 5. conclusion ............................................................................................................................................................................ 17 references ................................................................................................................................................................................ 17 citation | samer s. abu zer; samir s. yassin; mohamed r. al agha; khalid jamal khadoura (2016). radiation protection measures in radio-diagnostic centers in gaza hospitals, palestine. asian review of environmental and earth sciences, 3(1): 10-16. doi: 10.20448/journal.506/2016.3.1/506.1.10.17 issn | 2313-8173 this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group http://creativecommons.org/licenses/by/3.0/ http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.10.17 https://orcid.org/orcid-search/quick-search?searchquery=samer s. abu zer https://orcid.org/orcid-search/quick-search?searchquery=samir s. yassin https://orcid.org/orcid-search/quick-search?searchquery=mohamed r. al agha https://orcid.org/orcid-search/quick-search?searchquery=khalid jamal khadoura http://search.crossref.org/?q=10.20448/journal.506/2016.3.1/506.1.10.17 asian review of environmental and earth sciences, 2016, 3(1): 10-17 11 1. introduction ionizing radiation in medical imaging is one of the powerful diagnostic tools in medicine. radiation which is applied in radiology departments has hazardous effects on biological systems [1, 2]. the level of awareness concerning with radiation protection influences in staff behavior. if they have not enough information related to mentioned issue, their action will not be safe and resulted to adverse effects [3, 4]. all of these individuals may be considered radiation workers, depending on their level of exposure and on national regulations. all workers require appropriate monitoring continuously by common personnel dosimeters like film badge and thermo-luminescence dosimeter. they must also receive education and training appropriate to their jobs and protect by tools and equipment [5]. in gaza governorates hospitals, there is no radiation protection program, lack of clear information about radiation protection measures and guidelines. therefore, the study results will help in implementing modification to alleviate risk factors. in addition, to develop an action plan and new management strategies for radiation protection enhancements and provide clear information to the decision makers. 2. objectives the main objective of the study is to evaluation of radiation protection measures at governmental gaza governorates hospitals. the other specific objectives are:  to identify the availability of radiation protection devices in the radio-diagnostic centers.  to measure the level of radio-diagnostic workers awareness about radiation protection issues.  to measure the level of radio-diagnostic workers practices about radiation protection issues.  to evaluate the personal radiation exposure monitoring process.  to help the planners and decision makers to modify the future plans regarding radiation protection to be more and to develop radiation safety culture. 3. materials and methods the present study is a descriptive analytical cross sectional study. we carried out this study in nine governmental gaza governorates hospitals. the target population of this study is the radio-diagnostic workers who have been working at radio-diagnostic centers in these hospitals. this estimated approximately 185 medical radiographers and 45 radiologists. the hospitals were selected because of their large and diverse of their radio-diagnostic services. the sample size was calculated by using sample size calculator from the survey system on the web, with confidence level of 95% and confidence interval of 5. the calculated sample size was 144 of the 230 radiodiagnostic workers. we decided to give rise this number to 182 in order to increase the response rate and to compensate the uncertainties. the study instrument was face to face interview through close-ended structured questionnaire. the validity of the questionnaire was tested by six specialists in the fields of radiology, medical physics, public health and statistics. a pilot study was conducted before starting real data collection. it was served as a pre-test for the questionnaire to check the ambiguity in the question statements and the time taken to complete the questionnaire. twenty radiodiagnostic workers were chosen to participate in the pilot study. they were selected by the convenience method from the hospitals that have been previously identified. slight modifications were also done on the questionnaire. the questionnaire content reliability and internal consistency determined by using cronbach's alpha in spss. 3.1. the questionnaire consists of five parts and includes the following part one: consisted of eight questions about socio-demographic factors and related work information. this includes: age, sex, occupation, academic qualification, years of experience, name of hospital, type of radio-diagnostic machines who use it, and daily work hours inside the radio-diagnostic rooms. part two: consisted of ten questions related to the availability of radiation protection devices in the radiodiagnostic centers. this contains (lead apron, gonad shield, lead curtains, lead shields or barrier, thyroid shields, lead glass, lead gloves, breast shields, radiation warning signs and caution lights). part three: consisted of eighteen questions to measure the level of radio-diagnostic workers awareness about radiation protection issues. this also gives some information about the general understanding of radiation protection issues. part four: consisted of fifteen questions related to describe of radio-diagnostic workers practices about radiation protection issues. part five: consisted of six questions to evaluate the personal radiation exposure monitoring process. data checked, coded, entered and analyzed using spss 20 (statistical package for the social science inc. chicago, illinois usa, version 20) statistical package. 4. results and discussion tale (1), shows 79.1% (n=144) of participants are medical radiographers and 20.9% (n=38) are radiologists. most of radio-diagnostic workers that formulate 82.8%% (n=144) have a bachelor degree. there is a wide variation in sex of radio-diagnostic workers, where 76.1% (n=144) of the study participants are males and 23.9% (n=43) females. this result indicates that the most of radio-diagnostic workers are males and this is attributed to the community culture towards women who working in radiology field and their fear from transmitting the risk of radiation to their future generations. the study shows that the participants ages were between 30 and 39 years which formulates 46.4% (n=84) of the participants, this indicates that the radio-diagnostic population are young labors. asian review of environmental and earth sciences, 2016, 3(1): 10-17 12 the study population was categorized into four groups according to their practical experience and refers that most of the radio-diagnostic workers have sufficient practical experience in radio-diagnostic field. clearly, it is found that the largest number of study participants from al shifa medical complex, who formulates 31.3% (n=57) of the study participants. however, the lowest number of study participants from abdel aziz rantessi hospital who formulates 4.9% (n=9) of the participants, this result is not a surprise since the participants proportions depend on the number of radio-diagnostic workers in each hospital, where al shifa medical complex is a major one. basic x-ray machines is the most common used, which formulates 83% (n=151) of participants. while 14.8% (n=27) of participants used with mammography machines, this result is reasonable because the basic x-ray machines are the most prevalent in terms of the number and use in the hospitals. whereas, the dealing with the mammography machines restricted to females workers. most of radio-diagnostic workers that formulate 34.1% (n=60) working between 3 and 4 hours inside the radiodiagnostic rooms per day, while 27.8% (n=49) of the participants working between 2 and 3 hours per day. table-1. socio-demographic and related work factors of the study participants. item frequency percentage 1. age from 20-29 years 44 24.3% from 30-39 years 84 46.4% from 40-49 years 38 21% more than 50 years 15 8.3% 2. sex male 137 76.1% female 43 23.9% 3. occupation radiologist 38 20.9% medical radiographer 144 79.1% 4. academic qualification diploma 16 9.2% bachelor 144 82.8% higher degree 14 8% 5. practical experience 1-4 years 32 18% 5-9 years 64 36% 10-14 years 48 27% 15-20 years 34 19.1% 6. name of hospital abu yousef al najjar hospital 12 6.6% european gaza hospital 16 8.8% nasser medical complex 29 15.9% al aqsa martyrs hospital 20 11% al shifa medical complex 57 31.3% al naser pediatric hospital 12 6.6% abdel aziz rantessi martyr 9 4.9% kamal adwan martyr hospital 17 9.3% beit hanoun hospital 10 5.5% 7. type of radio-diagnostic machine basic x-ray 151 83% ct scan 80 44% fluoroscopy 107 58.8% panorama 44 24.2% mammography 27 14.8% portable x-ray 76 41.8% 8. daily work hours in radio-diagnostic rooms 1-2 hours 21 11.9% 2-3 hours 49 27.8% 3-4 hours 60 34.1% 4-5 hours 32 18.2% more than 5 hours 14 8% the personal radiation protection devices are the principal for radiology workers [6]. a visible warning sign and caution light required to alert individuals to radiological conditions [7]. however, according to the participants knowledge, it is about 35.2% of personal radiation protection devices are available in the radio-diagnostic centers at governmental gaza governorates hospitals, table 2. as it displays in the figure (4.26), the maximum rate about the availability of personal radiation protection devices specified to lead aprons and thyroid shields by 95.6% (n=174) and 75.8% (n=138) respectively. the minimum rate that related to the availability of personal radiation protection devices specified to lead curtains, breast shields and gonad shields by 5.5% (n=10), 7.1% (n=13) and 15.9% (n=29) respectively. asian review of environmental and earth sciences, 2016, 3(1): 10-17 13 table-2. participants response about the availability of radiation protection devices. radiation protection devices yes(frequency and percentage) no(frequency and percentage) don't know (frequency and percentage) lead aprons 174(95.7%) 7(3.8%) 1(0.5%) gonadal shields 29(16%) 142(78%) 11(6%) lead curtains 10(5.5%) 135(74.2%) 37(20.3%) lead shields / barriers 73(40.2%) 92(50.5%) 17(9.3%) thyroid shields 138(75.9%) 41(22.5%) 3(1.6%) lead glass 76(41.8%) 98(53.8%) 8(4.4%) lead gloves 38(20.9%) 134(73.6%) 10(5.5%) breast shields 13(7.1%) 155(85.2%) 14(7.7%) radiation warning signs 41(22.5%) 132(72.5%) 9(5%) caution lights 48(26.4%) 122(67%) 12(6.6%) average 35.2% 58.1% 6.7% as shown in figure1 in spite the fact that 74.8% of participants have awareness about radiation protection issues, but it is only about 53.4% of participants follows the radiation protection practices. this result is surprising and alarming. clearly it seems unsatisfactory and indicates that the approximately half of participants have negative practices toward radiation protection issues. figure-1. study participant awareness and practices level regarding radiation protection issues. table 3 shows that the radiation protection advisers are not available in the most of radio-diagnostic centers that surveyed. about 60.4% (n=111) of study participants have a personal radiation exposure monitoring device. approximately 55% (n=61) of participants who have personal radiation exposure monitoring device use this device during their work in radio-diagnostic rooms, while 31.5% (n=35) of participants sometimes use this device and 13.5% (n=15) of participants don’t use this device during their work in radio-diagnostic rooms. the most of participants who have a dosimeter don't receive guidance about the proper handling with the personal radiation exposure monitoring devices, this represents about 75.7% (n=84) of participants. there are a big problem in personal radiation exposure monitoring process, majority of the participants 64.9% (n=72) believe that the measurements results doesn’t take into consideration by the safety officers. there is no one of radio-diagnostic workers receive a new personal radiation exposure monitoring device when the devices collect to measure of radiation dose. table-3. responses of study participants to evaluation the personal radiation exposure monitoring processitems items frequency and percentage 1. does the hospital have radiation protection adviser (rpa)? yes 8(4.4%) no 174(95.6%) 2. does the hospital provide you with any personal radiation monitoring device? yes 111(60.4%) no 71(39.6%) 3. if yes, do you use it during your work in the radio-diagnostic rooms? yes 61(55%) sometimes 35(31.5%) no 15(13.5%) 4. did you receive a guidance about the proper handling with the personal radiation monitoring device? yes 27(24.3%) no 84(75.7%) 5. are the measurements results taken into consideration by the safety officers? yes 39(35.1%) no 72(64.9%) 6. do you receive another personal radiation monitoring device when the device collect to measure of radiation dose? yes 0(0%) no 111(100%) as shown in figure (2) there are a miscellaneous reasons advanced by the study participants about the negligence in personal radiation exposure monitoring process. majority of participants 64.9% (n=63) believe that there is no radiation safety officer to provide the service. while about 57.7% (n=56) believe that another reason was asian review of environmental and earth sciences, 2016, 3(1): 10-17 14 put forward by the participants. this is due to the carelessly of hospital management, that represent about 57.7% (n=56). another opinion reports that there is lack of fund to purchase these devices and this represents about 32.0% (n=31). finally, 24.7% (n=24) of participants believe that the radio-diagnostic workers do not request the dosimeters. figure-2. participants response about the reasons for lack of personal radiation exposure monitoring devices. the independent samples t-test, frequency, one-way analysis of variance (anova), mean and the standard deviation were carried out and developed in order to identify the relationship between the level of availability the personal radiation protection devices, awareness and practices regarding radiation protection issues and evaluation of personal radiation exposure monitoring process as a dependent variables. however, the socio-demographic and work related factors for workers as independent variables. according to one-way variance (anova) analysis, (p value=0.003), the results in table 4 reflect there is a difference in the practices mean among the radio-diagnostic workers according to their age groups. the highest mean value (72) was for age group more than 50 years, while the lowest mean value (49.05) was for age group between 30 and 39 years. clearly that the calculated p-value is less than the significant level which is equal 0.05 (p-value < 0.05).so, the alternative hypothesis that there is statistically significant relationship between the participants practices regarding radiation protection and their age groups is accepted. clearly that there is a statistically significant difference according to the participants age groups (p-value=0.037), this difference is highest among radio-diagnostic workers with age groups more than 50 years, with mean value (41.11). the lowest mean (23.11) is among age group between 20 and 29 years. this is logical result and reflects that the new employees are not included in the personal radiation exposure monitoring process. table-4. the dependent variables according to participants age groups items age no. mean std. f sig. availability of devices from 20-29 years 44 40.00 21.67 2.024 0.112 from 30-39 years 84 34.29 19.59 from 40-49 years 38 30.26 15.85 more than 50 years 15 39.33 18.31 awareness from 20-29 years 44 73.61 14.68 2.18 0.092 from 30-39 years 84 74.07 14.26 from 40-49 years 38 74.42 14.47 more than 50 years 15 83.70 9.73 practices from 20-29 years 44 53.03 21.23 4.721 0.003 from 30-39 years 84 49.05 21.45 from 40-49 years 38 55.44 25.66 more than 50 years 15 72.00 18.55 radiation monitoring from 20-29 years 44 23.11 26.22 2.879 0.037 from 30-39 years 84 33.93 25.67 from 40-49 years 38 25.00 26.78 more than 50 years 15 41.11 33.85 the results in table 5 shows that there are no statistically significant differences the dependent variables due to participants sex. table-5. the dependent variables according to participants sex items sex no. mean std. t sig. availability of devices male 137 34.67 18.87 -0.474 0.636 female 43 36.28 21.05 awareness male 137 74.53 14.72 -0.266 0.791 female 43 75.19 12.32 practices male 137 52.99 23.25 -0.047 0.963 female 43 53.18 21.01 radiation monitoring male 137 29.56 27.34 -0.548 0.584 female 43 32.17 26.82 according to one-way variance (anova) analysis in table 6 (p-value=0.029).there is a statistically significant relationship between radio-diagnostic workers awareness toward radiation protection issues due to their asian review of environmental and earth sciences, 2016, 3(1): 10-17 15 occupation. there are a highly statistically significant differencesbetween the radio-diagnostic workers evaluation regarding personal radiation exposure monitoring process and their occupation (p-value=0.000). table-6. the dependent variables according to participants occupation items occupation no. mean std. t sig. availability of devices radiologist 38 32.63 17.96 -0.902 0.368 medical radiographer 144 35.83 19.84 awareness radiologist 38 70.32 15.30 -2.199 0.029 medical radiographer 144 75.96 13.73 practices radiologist 38 48.07 25.94 -1.635 0.104 medical radiographer 144 54.86 21.89 radiation monitoring radiologist 38 8.77 16.32 -5.952 0.000 medical radiographer 144 35.88 26.76 clearly in table 7 that there is a statistically significant difference in the radio-diagnostic workers practices according to their academic qualification (p-value=0.008). this result may be attributed to the quality of education materials and curriculum given to the three different groups. there is statistically significant difference between the evaluation regarding personal radiation exposure monitoring process among radio-diagnostic workers and their academic qualifications (p-value=0.013). as shown in table 8 there is a statistically significant difference in the radio-diagnostic workers awareness level due to their years of practical experience (p-value=0.017). there is a highly statistically significant difference in the radio-diagnostic practices due to their practical experience years (p-value=0.000). table-7. the dependent variables according to participants academic qualification items education no. mean std. f sig. availability of devices diploma 16 31.25 19.28 0.435 0.648 b.sc. 144 36.11 20.11 higher degree 14 35.71 16.51 awareness diploma 16 78.13 10.44 0.462 0.631 b.sc. 144 74.50 14.68 higher degree 14 75.00 14.25 practices diploma 16 70.42 19.62 4.967 0.008 b.sc. 144 52.04 22.32 higher degree 14 55.24 23.45 radiation monitoring diploma 16 47.92 27.13 4.433 0.013 b.sc. 144 30.09 26.76 higher degree 14 20.24 25.47 this result may be attributed to long-term of occupational radiation doses for those who have more than 20 years of work. so, this group of radio-diagnostic workers has become more concerned about the health impacts from radiation exposures than those who have less period of experience. hence, they applied the protection procedures more carefully to decrease the probability of radiation risks on their health. there are a highly statistically significant differences in the evaluation of personal radiation exposure monitoring process due to their practical experience years (p-value=0.000). table-8. the dependent variables according to participants practical experience items experience no. mean std. f sig. availability of devices from 1-4 years 32 39.06 24.14 1.261 0.287 from 5-9 years 64 35.31 19.92 from 10-14 years 48 30.83 15.96 from 15-19 years 19 39.47 17.79 more than 20 years 15 32.00 16.56 awareness from 1-4 years 32 78.99 12.91 3.088 0.017 from 5-9 years 64 71.09 14.21 from 10-14 years 48 73.61 14.24 from 15-19 years 19 78.07 13.67 more than 20 years 15 81.48 13.55 practices from 1-4 years 32 53.13 18.97 7.493 0.000 from 5-9 years 64 47.19 22.04 from 10-14 years 48 49.72 22.04 from 15-19 years 19 67.02 22.50 more than 20 years 15 75.11 19.76 radiation monitoring from 1-4 years 32 13.54 20.93 5.414 0.000 from 5-9 years 64 32.29 25.70 from 10-14 years 48 30.21 25.65 from 15-19 years 19 33.33 31.43 more than 20 years 15 48.89 29.86 asian review of environmental and earth sciences, 2016, 3(1): 10-17 16 as shown in table 9 there are highly statistically significant differences in the participants evaluation of availability of radiation protection devices(p-value=0.000), participants awareness (p-value=0.028) and participants practices (p-value=0.001) due to their hospitals. table-9. the dependent variables according to participants hospitals items hospital no. mean std. f sig. availability of devices european gaza hospital 16 31.25 10.25 8.337 0.000 nasser medical complex 29 43.45 20.58 abu yousef al najjar hospital 12 22.50 6.22 al aqsa martyrs hospital 20 34.00 11.42 al shifa medical complex 57 38.77 19.28 abdel aziz rantessi hospital 9 63.33 11.18 al naser hospital 12 31.67 23.29 kamal adwan hospital 17 22.35 16.78 beit hanoun hospital 10 15.00 9.72 awareness european gaza hospital 16 70.83 15.52 2.221 0.028 nasser medical complex 29 71.26 13.03 abu yousef al najjar hospital 12 70.37 17.14 al aqsa martyrs hospital 20 74.17 16.74 al shifa medical complex 57 78.36 12.93 abdel aziz rantessi hospital 9 69.14 14.46 al naser hospital 12 85.65 14.88 kamal adwan hospital 17 73.53 8.68 beit hanoun hospital 10 71.67 13.21 practices european gaza hospital 16 43.33 26.22 3.484 0.001 nasser medical complex 29 42.76 21.49 abu yousef al najjar hospital 12 56.11 16.69 al aqsa martyrs hospital 20 42.00 25.05 al shifa medical complex 57 59.53 21.19 abdel aziz rantessi hospital 9 54.81 22.80 al naser hospital 12 67.22 13.77 kamal adwan hospital 17 56.08 19.73 beit hanoun hospital 10 63.33 25.39 radiation monitoring european gaza hospital 16 25.0 21.08 1.58 0.134 nasser medical complex 29 24.71 28.74 abu yousef al najjar hospital 12 45.83 18.97 al aqsa martyrs hospital 20 27.50 26.64 al shifa medical complex 57 26.90 28.65 abdel aziz rantessi hospital 9 42.59 22.22 al naser hospital 12 38.89 32.05 kamal adwan hospital 17 27.45 25.65 beit hanoun hospital 10 43.33 26.29 clearly in table 10 that there is a statistically significant difference in the radio-diagnostic workers practices according to their daily work hours (p-value=0.008). this difference is high among radio-diagnostic workers who work more than 5 hours (67.1), the lowest is among radio-diagnostic workers who work between 2 and 4 hours (46.7). table-10. the dependent variables according to participants daily work hours in radio-diagnostic rooms items daily work hours no. mean std. f sig. availability of devices from 1-2 hours 21 32.4 21.2 0.504 0.733 from 2-3 hours 49 36.9 22.7 from 2-4 hours 60 36.0 18.5 from 4-5 hours 32 33.1 17.5 more than 5 hours 14 40.0 15.2 awareness from 1-2 hours 21 74.6 13.6 1.928 0.108 from 2-3 hours 49 73.7 15.9 from 2-4 hours 60 72.3 14.8 from 4-5 hours 32 80.7 11.3 more than 5 hours 14 75.0 11.9 practices from 1-2 hours 21 56.2 20.5 4.192 0.003 from 2-3 hours 49 52.9 21.9 from 2-4 hours 60 46.7 21.7 from 4-5 hours 32 62.3 22.8 more than 5 hours 14 67.1 21.8 radiation monitoring from 1-2 hours 21 31.0 29.5 1.002 0.408 from 2-3 hours 49 32.7 26.1 from 2-4 hours 60 25.6 27.7 from 4-5 hours 32 35.9 28.4 more than 5 hours 14 25.0 25.9 asian review of environmental and earth sciences, 2016, 3(1): 10-17 17 5. conclusion a descriptive analytical cross sectional study, based on the analysis of data collected by a close-ended structured questionnaire consists of five parts which designed for matching the study needs and 182 radio-diagnostic workers participated in the work. we conducted the independent samples t-test, frequency and one-way analysis of variance (anova). these tests detect the difference between the availability of personal radiation protection devices, awareness and practices level regarding radiation protection issues and evaluation of personal radiation exposure monitoring process as a dependent variables. however, the socio-demographic and work related factors among radiodiagnostic workers are independent variables. according to the results displayed in chapter four, the participants reported that 35.2% of personal radiation protection devices are available in the radio-diagnostic centers at governmental gaza governorates hospitals. the results indicate unsatisfactory practices toward radiation protection issues, where approximately half of participants have negative practices. in general, the results revealed that there is an obvious poor of personal radiation exposure monitoring process. there is also a statistically significant difference in the participants awareness level due to their years of practical experience and occupation. overall, the results represented in this work reflect that majority of participants believe there is no radiation safety officer to provide the service. therefore, there is a desperate need for rules, regulations and radiation protection act in the field of radiation in medical field. references [1] l. persson and k. shrader-frechette, "an evaluation of the ethical principles of the icrp’s radiation protection standards for workers," health physics, vol. 80, pp. 225-234 2001. [2] e. karen, j. e. thomas, parnell-parmley, s. haidar, and r. moineddin, "assessment of radiation dose awareness among pediatricians," pediatr radiol., vol. 36, pp. 823-832, 2006. [3] r. jascobs, m. vanderstappen, r. bogaerts, and f. gijbels, "attitude of the belgian dentist population towards radiation protection," entomaxillofacial radiology, vol. 33, pp. 334-339 2004. [4] b. svenson, h. g. grondahl, and b. soderfeldt, "a logistic regression model for analyzing the relation between dentists attitudes, behavior and knowledge in oral radiology," acta. ondontologica scandinavica, vol. 56, pp. 215-219, 1998. [5] n. rahman, s. dhakam, a. shafqut, s. qadir, and t. f. ali, "knowledge and practice of radiation safety among invasive cardiologists," jpma, vol. 58, pp. 119-122, 2008. [6] w. klein, l. miller, s. balter, w. laskey, d. haines, a. norbash, and j. goldstein, "occupational health hazards in the interventional laboratory: time for a safer environment," catheterization and cardiovascular interventions journal, vol. 73, pp. 432-438, 2009. [7] radiation protection manual, "a publication of institute of nuclear medicine and allied science (inmas), drdo, delhi, india," radiological protection bulletin, vol. 231, pp. 18-23, 2010. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences issn: 2313-8173 vol. 3, no. 1, 1-9, 2016 http://www.asianonlinejournals.com/index.php/arees 1 the cop21 agreement and asian economies jan-erik lane1 1 institute of public policy in belgrade, geneva abstract the global agreement on climate change – cop21 – will have immediate consequences upon the large emitters of greenhouse gases (ghg) in asia. from 2018 there can be no increases of ghg:s and preferable some decreases. the unique global agreement speaks little about the economic consequences, but emissions and gdp are strongly linked through energy consumption. this article shows the situation for major economies in asia with regard to the connection between gdp and ghg:s. it remains to be seen how the implementation of this global treaty will play out. whether it has the force of public international law remains to be tested as well as whether all countries will ratify the treaty and abide by it. several asian countries have only 2 years to make major changes. keywords: cop21-agreement, climate change, global coordination, greenhouse gases emissions (ghg) – total versus per capita, energy consumption, south korea, china, india, indonesia, pakistan, singapore, japan, super fund, stern. contents 1. introduction ................................................................................................................................................................................. 2 2. the global scene ......................................................................................................................................................................... 2 3. the energy link ......................................................................................................................................................................... 2 4. country predicaments: asia ...................................................................................................................................................... 3 5. strategies ...................................................................................................................................................................................... 7 6. compensation, exemptions and a giant global fund ............................................................................................................ 8 7. conclusion .................................................................................................................................................................................... 8 references ........................................................................................................................................................................................ 9 citation | jan-erik lane (2016). the cop21 agreement and asian economies. asian review of environmental and earth sciences, 3(1): 1-9. doi: 10.20448/journal.506/2016.3.1/506.1.1.9 issn | 2313-8173 this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group http://creativecommons.org/licenses/by/3.0/ http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506/2016.3.1/506.1.1.9 asian review of environmental and earth sciences, 2016, 3(1): 1-9 2 1. introduction the governments of the states of the world have come up with the strategies to employ in the great global coordination meeting on climate change in paris. they have been told by the “gurus” of globalization that time is short for avoiding a global disaster with long-term unavoidably dire consequences for mankind. the occurrence of anthropogenic or anthropomorphic global warming makes mankind enter a new evolutionary stage where the climate of planet earth is affected by the social systems of men and women, especially their economic activities (gdp), this in turn transforms the climate change problematic +1.5, +2, +4, 6 or more – to a set of very difficult problems for the social sciences: can really global coordination on emission reduction policies be made and also work? the literature on the implementation of policies teaches us that successful achievement of goals by efficient means is hard to accomplish, even on a local or national government level. with so many players involved in global state coordination, there is a clear and large risk of coordination failures in what is basically an ocean prisoners’ dilemma game. and time is pressing, even though the cop21 framework speaks of a policy for the entire century. already from 2018-20 must the increase in greenhouse gases (ghg) or co2:s be halted in order to start decreasing to zero over the 21rst century. but policies reducing emissions are costly and may decrease economic development or growth in world with mass poverty. what policy measures will be employed in which countries? administrative decisions closing down coal plants, installing filters on coal burning? subsidising renewable energy sourcesat what cost? using market mechanisms like carbon tax or emission trading schemes? the social sciences will have lots to contribute to climate change policy-making, complementing the natural sciences. energy, emissions and gdp go together. the standard projections for energy need speak of an almost doubling of energy consumption to meet economic growth predictions, but how can these projections become reality under the restrictions from the cop21 agreement? 2. the present picture for planet earth figure 1 presents the major existing trends in population, emissions and gdp globallyup to now. there has taken place a considerable of not huge augmentation in global population, total emission of greenhouse gases and total economic output – gdp – from 1990 until today. what impacts most upon total ghg emissions is the general life style, measured by levels of gdp, but population growth of sourse leads to more of ghg emissions. figure-1. planet earth: population, gdp and emission 1990 source: ghc: world resources institute, gdp: world bank, population: united nations population division from figure 1 appears the augmentation yearly in ghg emissions since 1990, amounting to some 50 trillion kilos. generally speaking, in 2012 the following equations hold: ghg emissions = 8300*population; r2=0.87; life style as measured by the gdp is a major contributor: ghg emissions = 0.58*gdp; r2=0.53. in september 2015, the un agreed upon 17 global goals to achieve: end extreme poverty, fight inequality and injustice as well as halt climate change. yet, it is feared by the markets, governments and global business commentators that the gdp curve could start declining, as with china today where minor adjustments in gdp growth results in global financial market crises. economic growth would deliver the resources with which to reduce poverty. can really these three new un developmental objectives be achieved or could they conflict? economist jeffrey sachs, however, states that really halting ghg emissions growth rapidly would require a large reduction in global economic output. can governments in developing countries like e.g. china, india and indonesia conduct an effective global ecology policy with strong measures that halt ghg emissions growth as well as reduce them, but at the same time allow for continued economic growth? this would be a high priority from the point of view of environmental economics, betting upon renewable energy. if, on the other hand, reductions in emissions come with a large cost, one must ask the stern (2007) question: who is going to pay for correcting externalities? the cost problematic of ghg reductions is related to energy. 3. the energy link co2 emission s and all the greenhouse gases (ghg) are strongly linked with energy consumption in a broad sense, covering not only fuel, electricity but also transportation, food production and construction industry. without additional energy, economic development would be considerably lower or may even come to a halt. figure 2 shows this close link. asian review of environmental and earth sciences, 2016, 3(1): 1-9 3 figure-2. energy and ghc emissions 2012. equation: y=1.05x, r2=0.941 source: ghc: world resources institute, energy: international energy agency statistics figure 2 depicts the link between energy and emissions at the macro level, meaning that energy consumption or energy production could in small projects be carbon neutral, as demonstrated in several micro level projects. the problem is that generally speaking economic development is highly energy consuming, which in turn is polluting, as mostly fossil fuels. globally speaking it holds that higher levels of energy consumption are conducive to more ghg emissions. here, we have the global conundrum for the 21rst century: how to reduce ghg emissions without reducing economic development or economic growth that needs, it is true, more of energy consumption, or are really the three major objectives of the un above internally consistent?? look at figure 3 that contains the global picture of energy consumption today and the great part that goes to asian countries. it shows how large asia (east, south east and south asia) is in global energy consumption. the cop21 agreement will force asian economies to start decarbonising and increase energy efficiency much. figure 3 projects that asian economies could suffer from lower energy consumption growth rates. still, asian economies must go find additional energy and new sources of energy. figure-3. resource consumption by various parts of the world source: bp: energy outlook 2015 in appendix 1 we show energy consumption projections up to 2030, which can be found with several agencies or energy companies, where no reduction in energy consumption is actually predicted. moreover, the fossil fuels will increase their role as provider of energy, whereas the predicted augmentation for renewables is a tiny increase in comparison. the energy-emission dilemma is as follows: either – horn i energy consumption is decreased, especially of the fossil fuels and particularly carbon, or – horn ii the global economy manages to stage a rapid technology innovation on a huge scale, introducing massively carbon neutral energy. however, neither is likely, as economic development trumps environmental sustainability in general. figure 4 shows how large asia (east, south east and south asia) is in global energy consumption. the cop21 agreement will force asian economies to start decarbonising and increase energy efficiency much as well as innovate on a greater scale. let us look more closely at a few countries and how they face the energy-emissions-gdp dilemma. 4. asia the relationship between economic growth and emissions growth can only be one of increase in both, as asia has become « l'usine du monde ». although the countries in this region has had their so-called « take off » time points in different years after the second world war, in general one finds heavy emissions of greenhouse gases in this growth region: asean plus 3. consequently, the populous asian nations will be critical in the elaboration of any global ecology policy concerning not only climate change but also in general ecological sustainability. south korea this country has in an astonishing speed become one of the most technologically advanced countries in the world. however, its emission of ghg:s is huge, following its gd growth rates (figure 4). asian review of environmental and earth sciences, 2016, 3(1): 1-9 4 figure-4. south korea: equation: y = 0.693783x + 7.98; r2 = 0.97 source: ghc: world resources institute, gdp: world bank the clear link between the two curves in figure 4 comes as no surprise, confirming the general observations above for planet earth. turkey turkey has become a most important country, politically and economically in the asia minor thanks to a rapid economic development of a country with huge population. figure 5 supports this picture of turkey as no longer a developing country but as a developed nation and member of the oecd. typical of the turkish scene is the combination of strong economic development with heavy emissions augmentations. since the economic world organisations – the wb and imf – wish to have more of economic growth and look upon turkey as a growth engine, one must ask whether emissions growth really can be halted in this economic super power. figure-5. turkey: equation: y = 0,7837x; r² = 0,972 sources: ghc: world resources institute, gdp: world bank turkey has a huge influence in the new nations in asia, replacing the soviet republics, as they have considerable turkish speaking populations. often their trade is going through istanbul. china mainland china is now ranked as the largest ghg polluter in the world, when we look at aggregate totals, although not so when emissions per capita are examined. it has « dethroned » the us recently with india rapidly moving upwards too. relating ghg emissions to population size, china used to a rather small per capita emission, given its enormous population. but the per capita figure has gone up for china, although it is far from the top in the world. actually, the per capita figure for qatar (44) is much higher than that of china (6.7) (http://data.worldbank.org/indicator/en.atm.co2e.pc). now, look at figure 6. figure-6. china: equation: y = 0,5736x; r² = 0,9578 sources: ghc: world resources institute, gdp: world bank http://data.worldbank.org/indicator/en.atm.co2e.pc asian review of environmental and earth sciences, 2016, 3(1): 1-9 5 chinese economic development has been driven by massively using resources – mostly coal, gas and iron from australia that emit much greenhouse gases, like fossil fuels and cement. especially, china operates a large number of coal-fired power stations – often without filters in order to generate electricity. thus, coal-fired power stations in the millions often lack anti-pollution filters, hurt environment quality for ordinary citizens daily. in addition, china now has the largest and fastest growing car market in the world, burning oil and gas. chinese ecology policy has hardly been given much thought or high priority until lately by government or been seriously developed by officials and bureaux. its leaders talk much about « green values », actually more and more every day, but concrete measures are often lacking. the promise of halting co2 emissions in relation to economic growth after 2018=2020 is perhaps a meaningless posture, as economic growth still will power ahead, although not as the same pace as between 1990-2010. a relative target will not do, as it is the absolute totals that must be decreased. the 2030 promise to effectively reduce ghg:s can be reneged upon. and the time table is for such relative reductions is too late for global policy-making to be effective in halting climate change. the chinese picture above may be compared with outcomes for a few other major developing countries in order to arrive at a comprehensively true global picture. generally speaking, the higher the total affluence of a country, the more this nation emits and the larger the population, the more of ghg:s. thus, one would expect to find lower total levels for small developing countries. how about a giant like india, predicted to overtake china in the size of population and eagerly pushing for economic growth around 6-7 per cent? india except recently, ecological policy-making has bowed to the overarching preference in india, namely rapid economic development, driven by energy consumption like coal and oil. india also has a rapidly expanding car market, which besides the huge number of highly polluting scooters creates sometimes breathing problems in its mega-cities (figure 7). figure-7. india: equation: y = 0,6093x + 4,7605; r² = 0,9954 sources: ghc: world resources institute, united nations framework on climate change ghg inventory submissions, gdp: world banksource figure 7 indicates no halting or decrease of emissions growth at all for this true giant nation. the government of india has an outspoken preference for economic growth > 5 per cent no matter what, which is considered necessary for lifting millions out of abject poverty. thus, india favours the employment of cheap energy line coal for electricity production – 300 million lacking that. cutting emissions would entail reducing economic growth rates – so the argument goes at least. the preoccupation of the indian government and several economists, dreaming about the great « catch-up » with china and the west, is to negotiate exceptions for india, if a global ecology policy is enacted. redistribution looms large in india's strategy, arguing that affluent countries should cut back the most or help financing advanced technology in poor nations. indonesia developing countries have in general one over-arching priority, namely to « catch-up » with developed countries. the catch-up strategy uses lots of cheap energy to raise economic output fast. energy consumption tends to result in ghg emissions, except for wind, hydro and nuclear power. so far most developing countries have opted for rapid economic growth, at the expense of environmental concerns. thus, we expect to find considerable increases below for ghg:s, looking at a dynamic developing country that is finally « taking off », namely giant indonesia (figure 8). asian review of environmental and earth sciences, 2016, 3(1): 1-9 6 figure-8. indonesia : equation : y = 0,6554x + 9,8515; r² = 0,9267 sources: ghc: world resources institute, gdp: world bank source: the upward trend for ghc emissions in indonisia reflects closely its economic growth rates. given its huge population, this country is a major polluter, including the haze from kalimantan, or indonisan borneo. indonesia has drawn one correct conclusion, namely building a giant wall protection for its capital, jakarta, against future sea level rise pakistan consider then pakistan (figure 9) another giant nation in south asia ! it has already lost land to sea level rise. figure-9. pakistan: equation: y = 0,8948x; r² = 0,9989 sources: ghc: world resources institute, gdp: world banksource: the trend is the same for this huge developing country as for already developed south korea, i.e. ghc emissions up and following economic developetment. how to halte missions and still maintain economic growth in this poor nation ? singapore singapore – its politcal leaders, public officials as well as the scholars at universities and colleges speak much about the climate change predicament. thus, the city-state mentions a lot of activities and programs aimed at reducing carbon emissions and the outflow of other greenhouse pollutants. singapore is assertive about its aim to be an ecology model for the future, betting much now upon the use of renewables. yet, let us look at the facts in figure 10. figure-10. singapore: equation:y = 0.34056 + 15.91 ; r2 = 0.85 source: ghc: world resources institute, gdp: world bank asian review of environmental and earth sciences, 2016, 3(1): 1-9 7 the city-state is extremely affluent, meaning that it employs massive amounts of energy to run a huge airport, a world harbour and an omnipresent use of air-conditioners everywhere, consuming electricity and emitting ghc:s. in addition, it cleans its waste water up to 100 per cent, which requires lots of energy. it burns massive amounts of oil and gas for its electricity generation. japan japan will no longer rely much upon nuclear power, having one power plant is use today. its emissions have gone done recently, but seem to be on the rise again due to use of fossil fuel increasingly again (figure 11). : figure-11. japan: ln (ghg / kg co2 eq and ln (gdp / constant value 2005 usd); japan: equa.: 0,0828x; r² = 0,1729 sources: ghc: world resources institute, united nations framework on climate change ghg inventory submissions, gdp: world bank the decrease in emissions for japan reflects the country’s post-industrial developments. production sites have been moved out of japan with heavy investments in other asian countries as well as the eu and the us. but the loss of energy from some of its nuclear power stations poses a great problem for the country – what to use instead along with the cop21 requirement of decarbonisation? 5. strategies developing countries all display increasing emissions of ghc, as they employ lots of energy to close the gap to the developed world. when faced with a demand for reductions of emissions from the developed nations, developing countries may respond with the following strategies: a) counter demand for cuts by countries with high emissions per capita; b) demands for financial assistance to help make the energy transition; c) acceptance of a halt to emissions growth but no reductions until 2050. 5.1. total emissions or emissions per person how is the necessary reduction in ghg emissions to be distributed onto the countries in the world? the policy relevant question is: the same percentage figure for all, or more by the rich countries and less by the poor? the confusing fact is that total emissions and emissions per capita do not at all coincide – see figure 12. figure-12. total emissions and per capita emission; equation: y = 0,2116x + 3,267; r² = 0,17 source: world resources institute, gdp: world bank, population: united nations population division figure 10 shows that all possibilities exist: big total emission and low per capita emissions, small total emissions and high per capita emissions, etc. which country is to cut back emissions the most? some developing countries have huge total emissions, but they may argue that rich countries with high per capita emissions should make most reductions. it is true that per capita emissions follow the affluence of a country, i.e. gdp per capita – see figure 13. asian review of environmental and earth sciences, 2016, 3(1): 1-9 8 figure-13. gdp per capita and ghg per capita; equation: y = 0,5496x + 3,8985; r² = 0,6537 source: world resources institute, gdp: world bank, population: united nations population division thus, poor countries could claim that rich countries with high per capita emissions to the right in figure 9 can not only afford the reductions, but that this redistribution would also be fair. the problem is only that several countries with high per capita emissions have tiny populations. the biggest countries in the world – the g20 – are responsible for almost 80 per cent of all ghg emissions! from a global point of view concerning emission efficiency, decreases by the huge emitters make most sense, like china, india, indonesia, brazil, nigeria, south africa, the us and canada as well as large eu countries. how about the un ambition to maximise both objectives: economic development and ecological sustainability, with the basic notion of country fairness? 6. fairness, compensation and the global ecology fund already economist stern [1] argued that reducing emissions would be extremely costly, either lowering economic growth or requiring enormous new investments. to overcome this objection, he launched the idea of a global fund to transfer money from the rich to the poor countries as well as accepting a moratorium for certain developing nations. the proposal of a huge global redistribution is within the cop21 agreement. the suggestion from the kyoto agreement that some countries could be excluded from a reduction scheme for some time period now seems unacceptable: when some cut, other could expand – the perfect pd game! given the economic stagnation in the oecd world, the idea of a super fund also appears unrealistic. one could ask, and the us congress will do so on the ratification of cop21: why should the us pay to china to lower its emissions, when it is in the interest of china itself to do so? 7. conclusion climate change has become the major problem in international political economy. but is it likely that global coordination will work according to the cop21 treaty? each country now has to develop a realistic strategy to cope with the consequences of climate change – resilience. climate change is driven by both population growth and more and more energy consumption for economic development or growth. the universal call for economic growth has so far trumped any efforts at holding back gdp, because the life style of freedom from poverty drives people. themost realistic hope is that major technological breakthroughs will be forthcoming in time allowing for carbon neutral energy. it exists already such know-how but its scale is too small. in standard energy projections up to 2030 (see appendix), planet earth will continue to rely heavily upon the fossil fuels, which results no doubt in more of ghg:s! for the huge asian countries, it is vital to embark on both decarbonisation – close the coal fired power stations and innovation in energy with massive new technologies for renewable energy sources and much better filters for the use of fossil fuels. economic development will depend more and more upon energy efficiency – see figure 14. figure-14. energy and gdp source: growth in world energy consumption (based on bp data) and growth in world real gdp asian review of environmental and earth sciences, 2016, 3(1): 1-9 9 the cop21 agreement makes it imperative for asian economies to develop advanced energy plans, finding new sources but also employing the existing ones more efficiently! sources international energy agency statistics united nations framework on climate change ghg inventory submissions ghg: world resources institute (washington, dc) gdp: world bank (washington, dc) population: (1) united nations population division. world population prospects, (2) united nations statistical division. population and vital statistics report (various years), (3) census reports and other statistical publications from national statistical offices, (4) eurostat: demographic statistics, (5) secretariat of the pacific community: statistics and demography programme, and (6) u.s. census bureau: international database. bp energy outlook 2015. appendix 1. energy consumption projections appendix-1. energy predictions – 2030 source: global total primary energy consumption by fuel, www.eea.europa.eu911 2008. references [1] n. stern, the economics of climate change: the stern review. cambridge: cambridge university press, 2007. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. asian review of environmental and earth sciences vol. 4, no. 1, 58-67, 2017 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2017.41.58.64 58 effects of anthropogenic activities and eutrophication along river chanchaga, minna, nigeria wakili, b. y1  nsofor g.n2 suleiman, y. m3 mohammed. a. e4 ( corresponding author) 1,2,3,4department of geography, federal university of technology, minna, nigeria abstract river chanchaga is the major source of drinking water in minna, nigeria. this river has been a medium to an increasing pollution loads from contaminated runoff from different land uses degrading aquatic ecosystem and water quality in the river.this paper investigates the threat of anthropogenic influence on river environment and aquatic ecosystem distortion of river chanchaga, minna, nigeria. field work which include interview and observation methods were used to collect data on effect of anthropogenic and eutrophication along the study area. a total of two hundred and fifty (250) people accounting for 0.5% of the total population were interviewed, making it eight per each community in thirty settlements along the study area. physical observation of deforestation around sample sites spatially distributed along river chanchaga depicted in figure 2 was carried out to study mining activities, farming practice, crop types, and fallow duration to generate the mean and percentages of different anthropogenic activities along the study area. the findings revealed that deforestation is links to high demand for fire wood, lumbering, irrigation farming bank-side mining for sand and gold as depicted in plat 1 and 2. eutrophication at the upper course of river is links to high inflow of agricultural wastes and seasonal nature of the river from site a to c evident from table 4 and constant flow from site c to k as a result of released water from tagwai dam that keeps (site c, the confluence of river chanchaga and river numui) middle and lower courses of river chanchaga with sustainable moving water. the result further indicated that continue increase of pollution has a direct relationship to an increasing level of human activities like deforestation, mining activities and agricultural practices along the study area. the result also shows that there is decline in fallow duration as indicated in table 1 and increase environmental related issues such as soil erosion, water floor (depth) reduction and distortion of river morphology of the study area. it is therefore recommended that the identified anthropogenic activities that lead to pollution and eutrophication such as river-side deforestation, irrigation farming, mining and other related environmental problems should be regulated and discourages to avoid further increase of pollution and distortion of river environment of the study area. keywords: anthropogenic, pollution, deforestation, eutrophication, environment. citation | wakili, b. y; nsofor g.n; suleiman, y. m; mohammed. a. e (2017). effects of anthropogenic activities and eutrophication along river chanchaga, minna, nigeria. asian review of environmental and earth sciences, 4(1): 58-64. history: received: 13 november 2017 revised: 27 november 2017 accepted: 12 december 2017 published: 21 december 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 59 2. the study area ................................................................................................................................................................................. 59 3. materials and method ..................................................................................................................................................................... 60 4. results and discussions .................................................................................................................................................................. 60 5. conclusion and recommendations ............................................................................................................................................... 64 references .............................................................................................................................................................................................. 64 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=wakili, b. y https://orcid.org/orcid-search/quick-search?searchquery=nsofor g.n https://orcid.org/orcid-search/quick-search?searchquery=suleiman, y. m https://orcid.org/orcid-search/quick-search?searchquery=mohammed. a. e https://orcid.org/orcid-search/quick-search?searchquery=wakili, b. y https://orcid.org/orcid-search/quick-search?searchquery=nsofor g.n https://orcid.org/orcid-search/quick-search?searchquery=suleiman, y. m https://orcid.org/orcid-search/quick-search?searchquery=mohammed. a. e https://orcid.org/orcid-search/quick-search?searchquery=wakili, b. y https://orcid.org/orcid-search/quick-search?searchquery=nsofor g.n https://orcid.org/orcid-search/quick-search?searchquery=suleiman, y. m https://orcid.org/orcid-search/quick-search?searchquery=mohammed. a. e https://orcid.org/orcid-search/quick-search?searchquery=wakili, b. y https://orcid.org/orcid-search/quick-search?searchquery=nsofor g.n https://orcid.org/orcid-search/quick-search?searchquery=suleiman, y. m https://orcid.org/orcid-search/quick-search?searchquery=mohammed. a. e https://orcid.org/orcid-search/quick-search?searchquery=wakili, b. y https://orcid.org/orcid-search/quick-search?searchquery=nsofor g.n https://orcid.org/orcid-search/quick-search?searchquery=suleiman, y. m https://orcid.org/orcid-search/quick-search?searchquery=mohammed. a. e asian review of environmental and earth sciences, 2017, 4(1): 58-64 59 1. introduction there are many ways, by which several water sources include harbors, bays, creeks, canals, swamps, lakes, and streams, which come together and form a small network of river. in nigeria, these water ways (rivers) have been the medium to an increasing pollution load from contaminated runoff water from agriculture, domestic (residential), industrial, commercial, institutional (schools, hospitals), recreational, like tourism centers and event centers adakole and annue [1]. ogbogu and hassan [2] made mention that contaminants usually carried into water bodies (stream/rivers) especially in areas of heavy anthropogenic activities degrade the aquatic habitat and water quality. to some level freshness is also attributed to geochemical and biochemical sedimentation [2]. river chanchaga is a major effluent receiving stream with many gutters inflow to it. it is also use for irrigation of crops as well as source of drinking water for cattle during the dry season period [3]. at the catchments, there is challenge of land cover destruction that affects negatively on the river (river chanchaga) and reflected on the proliferation of water hyacinth infestation [4]. river chanchaga presents a good example of localities that have undergone extensive land use and land cover changes since the attainment of independence and subsequent population growth. the development has been a threat to the sustainability of its natural resource endowments [5]. public concern is now focused on how human impact on aquatic life or habitat loss and fragmentation are predominant factors affecting biodiversity loss [6]. conservation strategies are therefore, needed in order to offset such impacts on animal populations. polluted water has direct effect on health in the form of bacterial or viral disease, production of cancer, genetic defects and varieties of acute and chronic toxicity in human beings [7]. water pollution affects ecosystems through which an impact on human beings may not consequently be left. hence, household detergents that contain phosphate may flow into oligotrophic lakes and lead to eutrophication of the water bodies. muhammad [8] pointed to the socioeconomic importance of river and postulated that it is the modifier of micro climatic conditions around its immediate surroundings. though the importance of the river is recognized the emanating situation along river chanchaga is not environmentally friendly. this is true because the morphology of the river has been undergoing alteration and degradation of its environment.this challenge require and immediate attention to checked environmental degradations and eco-system disorders. this river is also for dry season irrigation farming and for domestic activities (such as construction of houses around its bank and neighboring village communities and excavation of sand [8]. 2. the study area river chanchaga transverses muya, shiroro, paikoro, bosso and katcha local government areas and can be located on longitude 6033’e – longitude 6038’e and latitude 9037’n – latitude 9040’n. the total land area covered by the basin is 159,259 km [8]. figure-1. the study area (river chanchaga, niger state, nigeria) source: remote sensing laboratory, department of geography, federal university of technology, minna, nigeria asian review of environmental and earth sciences, 2017, 4(1): 58-64 60 3. materials and method the methodology used for this research employed the use of descriptive analysis. it involved the use of tables, charts and simple percentages. therefore, both quantitative and qualitative measures were used for direct measurement of water channel morphology, river channel characteristics as well as extent of water pollution in the river [8]. generally, primary data were collected through the field surveys and 250 questionnaires accounting for 0.5% of the total population of the study area were administered to ascertain salient environmental features along river chanchaga. identification of different types of anthropogenic activities using camera, ranging poles and stones were conducted, investigated and analyzed. secondary data were collected as well through consultation of books of past related subject matter of the study. 4. results and discussions the identification is of different anthropogenic activities along river chanchaga include deforestation, mining, agricultural practices and other activities like industrial activities, oil droplets from mechanic sites and construction activities 4.1. deforestation and its effects in river chanchaga basin deforestation is understood to be an indiscriminating felling of trees or exploitation or clearance of the forest at particular geographical locations without any effort at replacing them. the possible consequences of deforestation vary from one point to another. the study reveals in figure 2 from site a to k, that site d (under chanchaga town bridge) has the highest intensive cutting down of trees and land clearance; this is because the continuous farming practices (irrigation and normal farming activities are taking place) in all seasons of the year with zero fallow duration. other sample sites that followed site b include sites g, e, f, h, j and i where tuber and cereal crops farming are at alarming rate because of population pressure as indicated in figure 2. site k has lowest rate of deforestation activities. it was found that farming for tuber and cereal crops is less at this area as presented in table 1. this resulted into the loss of species and biodiversity in aquatic ecosystem of river chanchaga due to excessive artificial alteration of study area. the affected areas of deforestation are as presented in plate 1 and 2. figure-2. deforestation around water sampling sites spatially distributed along river chanchaga source: department of geography, federal university of technology, minna another source of effect is provision of fuel wood and charcoal: the demand for domestic fuel wood is another factor accelerating deforestation along river chanchaga. firewood and charcoal are the main sources of asian review of environmental and earth sciences, 2017, 4(1): 58-64 61 energy for domestic purpose as some trees species are particularly important due to the burning efficiency of their wood. the most important are vitexdomianaprosipis africana, bonataxcostatum, and borassusasthiopium. these exploited in large quantities as presented in plate 1 and 2 plate-1. cutting down of trees for charcoal and medicinal purposes plate-2. deforestation for firewood along river chanchaga 4.2. medicinal properties of the trees extraction the extractions made from the leaves, branches, barks and roots depend on the type of medicine and intensity of extraction. this may cause tree to die. other minor causes are settlement and urbanization, farming, construction of roads, building, grazing and mining, which are the major characteristics along the upstream and downstream upland area of river chanchaga. it was observed that these dead plants wastes get transported by wind and runoff into nearby water source to degrade the water quality in the river as depicted in plate 1. 4.3. farming activities this is deforestation process which involves large scale clearance of vegetation cover for farming due to increasing population at particular geographical areas. the level of disturbance attributed to such land use can either be intermediate or high. the traditional bush fallow cultivation system of river chanchaga characterized by the annual cycle of forest clearance is no longer tenable. this is cultivation for two to three years and then abandoned for succession to forest. the lengths of the fallow (nowadays) mainly are determined by land availability and population pressure at particular place for specific period. the land clearance for cultivation of food crops and fuel wood is as presented in plate 3. the farming practices and crops with their subsequence wastes generated that cause’s water pollution and eutrophication is presented in table 1. asian review of environmental and earth sciences, 2017, 4(1): 58-64 62 table-1. farming practices, crop types and fallow duration along river chanchaga sample site vicinity crops produced farming practices duration of fallow (years) a maize, guinea corn, yam, ground nut, millet, potato fertilizer application, mix farming, bush burning, manure spreading, grazing of animal, shifting cultivation 2 b yam, guinea corn, maize, cassava, fishing, mango fertilizer application, mix farming, bush burning, manure spreading, grazing of animal, shifting cultivation 1 c yam, guinea corn, maize, millet, cassava, fishing, mango, guava, plantain fertilizer application, mix farming, bush burning, manure spreading, grazing of animal, shifting cultivation 1 d rice, yam, guinea corn, millet, groundnut, sugarcane, banana, potato, mango irrigation, mix farming, continuous cropping, bush burning 0 e yam, cassava, millet, maize, guinea corn, ground nut continuous farming, bush burning, shifting cultivation 1 f yam, cassava, millet, maize, guinea corn, ground nut continuous farming, bush burning 1 g yam, cassava, sugarcane, maize, guinea corn continuous farming, bush burning 2 h rice, maize, guinea corn, plantain fishing, rearing of farm animals 3 i rice, yam, guinea corn shifting cultivation, mix farming 2 j rice, yam, maize, guinea corn shifting cultivation, mix farming 2 k rice, yam, guinea corn, maize shifting cultivation, mix farming, bush fallow 3 source: author's field work (2016) plate-3. land clearance of over fifty hectare due to continuous irrigation farming practices behindchanchaga market 4.4. mining activities mining ranked third with 12 accounting for 4.8% of the total anthropogenic influences on river chanchaga water quality as depicted in table 2. table-2. identified sites for mining for sand and gold course of river chanchaga mining sites sand gold upper 13 12 middle 45 26 lower 7 4 total 65 42 source: author's field work (2016) 4.5. agricultural practices along the study area agricultural practices ranked the highest with 175 accounting for 70% as indicated in table 3 and plate 5. asian review of environmental and earth sciences, 2017, 4(1): 58-64 63 table-3. anthropogenic influences on river chanchaga water quality s/no. anthropogenic activities frequency (no. of respondents) percentage (%) 1 agricultural activities 175 70 2 construction/road &residential 38 15.2 3 mining activities 12 4.8 4 industrial 3 1.2 5 institutional 3 1.2 6 commercial 7 2.8 7 others 12 4.8 total 250 100 source: author's field work (2016) 4.6. irrigation irrigation farming alone with 79 accounting for 31.6% of the total agricultural activities with other remaining agricultural influence such as animal rearing and upland farming along the river with 96 accounting for 38.4% making a total of 175 accounting for 70% of the total agricultural activities shown in table 3. irrigation is the artificial application of water on farm crops in the dry season or during the drought period. it is the major contributor to water pollution especially during dry season period. it was observed that pesticide, fertilizer and other agrochemicals applied on the crops are washed directly into the water body. chanchaga town has the highest land area coverage for irrigation farming with about 70% and the remaining 30% for other areas along the study area. irrigation farming practice is as presented in plate 4. plate-4. irrigation farming within river bank. 4.7. industrial activities there are five identifiable block industries by chanchaga township bridge, off minna-paiko road, three soap factories and one pharmaceutical industry (danadam pharmaceutical industry) that discharge their effluence into river chanchaga, the effluence and washed detergent discharged degrade water quality in the river, thereby increasing the alkalinity and acidity of this river. dust from block industries settles immediately after release and increases suspended particles in the water. however, there is less industrial influence on river chanchaga water quality as they are few light industries along the river. plate 5 is one of the examples of such anthropogenic activities along the study area. plate-5. block industry with about 8.60 m setback to the river chanchaga asian review of environmental and earth sciences, 2017, 4(1): 58-64 64 4.8. eutrophication and its effects on river chanchaga spatial-temporal eutrophic areas in river chanchaga are presented in table 4. table-4. spatial-temporal eutrophic areas in river chanchaga s/n river course frequency characteristics 1. upper 5 seasonal 2. middle 0 not seasonal 3. lower 0 not seasonal source: author's field work (2016) the occurrence of eutrophication only at upper course could be as a result of seasonal nature of the river at this part of the study area. this type of degradation products cause knock-on-effect in the form of oxygen deficiency and fish kill. 5. conclusion and recommendations despite the environmental education, it is bound to be complimentary increase of anthropogenic activities in order to satisfy the demand of people residing around the area. anthropogenic forces are affecting negatively on the natural state of river chanchaga by reducing the quality and natural beauty of the river surrounding, habitat quality and affect the availability of quality aquatic resources that can served as food and beautifying the riverside environments. there should be public enlightenment programme so that people will be able to identify the implications of indiscriminate anthropogenic forcing practices along the river. human activities that may lead to pollution or contamination and eutrophication such as riverside deforestation, irrigation farming and other related environmental issues should be regulated and even discourage. deforestation should be discouraged to avoid causing ecological imbalance of river chanchaga aquatic ecosystem. references [1] j. a. adakole and p. a. annue, "benthic macro invertebrates as indicators of environmental quality of an urban stream zaria, northern nigeria," journal of aquatic science, vol. 18, pp. 85-92, 2003. view at google scholar | view at publisher [2] s. s. ogbogu and a. i. hassan, "effects of sewage on the physico-chemical variables and ephemeroptera (mayfly) larvae of a stream-reservoir system," journal of aquatic science, vol. 11, pp. 43-55, 1996. view at google scholar [3] i. maureen, "water pollution and its implication for aquatic resources and conservation on river chanchaga, minna, nigeria," environmental monitoring and assessment, vol. 107, pp. 56-64, 2002. [4] m. simon, j. onywere, i. mironga, and s. immaculate, "the open environmental engineering," journal of environment, vol. 5, pp. 918, 2012. [5] a. s. abbakar, lecture note on environmental management. minna, nigeria: federal university of technology, 2011. [6] i. fahrig, "relative effect of habitat loss and fragmentation in population existation," journal of wild life management, vol. 61, pp. 603-610, 1997. view at google scholar | view at publisher [7] a. s. halilu, "water pollution lecture notes on environmental hazards at federal university of technology, minna, niger state, nigeria," 2001. [8] b. y. muhammad, "an assessment of the effect of channelized river suka drainage project on the physical environment downstream in minna, niger state, nigeria," 2012. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=benthic%20macro%20invertebrates%20as%20indicators%20of%20environmental%20quality%20of%20an%20urban%20stream%20zaria,%20northern%20nigeria http://dx.doi.org/10.4314/jas.v18i2.19948 https://scholar.google.com/scholar?hl=en&q=effects%20of%20sewage%20on%20the%20physico-chemical%20variables%20and%20ephemeroptera%20(mayfly)%20larvae%20of%20a%20stream-reservoir%20system https://scholar.google.com/scholar?hl=en&q=relative%20effect%20of%20habitat%20loss%20and%20fragmentation%20in%20population%20existation http://dx.doi.org/10.2307/3802168 26 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 26-34, 2020 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.26.34 © 2020 by the authors; licensee asian online journal publishing group assessment of reference evapotranspiration estimation models olotu yahaya1 iyawe hope2 olatunde m.b3 olatunde f.o4 ( corresponding author) 1department of agricultural & bio-envi eng., auchi polytechnic, auchi, nigeria. 2department of urban & regional planning, auchi polytechnic, auchi, nigeria. 3,4department of surveying & geoinformatics, auchi polytechnic, auchi, nigeria. abstract reference evapotranspiration (eto) is an important factor in estimating crop water requirement, water resource management and designing irrigation scheduling. this study matches the outputs of open pans and blaney criddle (bc) to cropwat irrigation simulation software using 20-year daily weather data of auchi and its environs were acquired from the nigeria meteorological station (nmet) as baseline weather dataset. thus, the baseline weather data was reproduced using a general circulation model for data re-analysis. the accuracy of each model was evaluated using various statistical metrics. eto estimated from the four models were compared with the cropwat model, an irrigation software program used for solar radiation (rs), reference evapotranspiration (eto) and crop water requirement (cwr) calculations. validation outputs have the correlation values (r2) of 0.587, 0.536, 0.511 and 0.513 for etobc-eto cropwat, etobtetocropwat, eto aus-eto cropwat, and etous-etocropwat respectively. this result indicates a marginal good fit between the estimated reference evapotranspiration (eto) from each model and cropwat irrigation software. however, there were discrepancies between the simulated and computed reference evapotranspiration (eto) for the model with blaney criddle and australia pan having correlation (r2)) and bias value (ab) of 0.223; 0.241 and 2.30; 2.00 respectively. in conclusion, all the selected reference evapotranspiration (eto) estimating models have strong capabilities of providing accurate outcome be useful for water resources and hydrological modeling. keywords: reference evapotranspiration, cropwat model, water management. citation | olotu yahaya; iyawe hope; olatunde m.b; olatunde f.o (2020). assessment of reference evapotranspiration estimation models. asian review of environmental and earth sciences, 7(1): 26-34. history: received: 18 november 2019 revised: 23 december 2019 accepted: 28 january 2020 published: 10 march 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 27 2. materials and methods ................................................................................................................................................................... 27 3. results and discussion ................................................................................................................................................................... 30 4. conclusion ......................................................................................................................................................................................... 31 references .............................................................................................................................................................................................. 31 http://asianonlinejournals.com/index.php/arees/article/view/1390 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.26.34&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2020, 7(1): 26-34 27 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study matches the outputs of open pans and blaney criddle (bc) to cropwat irrigation simulation software using 20-year daily weather data of auchi and its environs were acquired from the nigeria meteorological station (nmet) as baseline weather dataset. 1. introduction severe water scarcity occurs in many countries particularly largely in nigeria and agricultural water use is progressively becoming more limited in the light of growing water demand of various sectors [1]. water management for crop suitability needs a comprehensive understanding of the climate, particularly, rainfall and evapotranspiration [2]. in developing nations like nigeria, where there is a shortage of direct measurements of evapotranspiration, evapotranspiration can be estimated indirectly using climatological data [3]. the penman monteith fao-56 equation is recommended for the estimation of reference evapotranspiration and provides a reliable reference evapotranspiration and provides a reliable reference evapotranspiration (eto) value under different climate conditions. evapotranspiration (et) is considered to be the dominant component of the hydrologic cycle due to the fact that about 60% of annual precipitation falling over the land surface is returned to atmosphere as et [4]. evapotranspiration and transpiration process take place simultaneously in any catchment area, and therefore, cannot be separated in the analysis and evaluation of water budget for a district [5]. the estimation of evapotranspiration is important for irrigation engineering applications and for studies relating to hydrologic water balance, water resource planning and management and land use planning. the estimate of reference evapotranspiration is important in crop water requirement and development of irrigation scheduling. the general knowledge of the spatial distribution of reference evapotranspiration (et0) is still unclear despite its importance for global ecosystem research [6]. one reason is that et0 is difficult to observe directly as it depends on several meteorological parameters which are observed only at major stations [7]. field measurement of meteorological variables is a critical part of evapotranspiration estimation process. measurement and recording errors in field variable result in evapotranspiration estimation errors [6]. there have been significant processes in the capability of near surface meteorological variable measurement such as temperature, precipitation, wind speed, solar radiation and humidity using automated climate stations [7]. this has the effects of simplifying evapotranspiration model usage. crop evapotranspiration is estimated by multiplying the reference evapotranspiration by crop specific crop coefficient (kc) values at different crop growth stages. moreover, different reference evapotranspiration methods have been developed over the years range from direct measurement from a reference surface such as alfalfa grass [7, 8] or can be computed from weather data based methods i.e. (a) temperature based [7, 9] (b) radiation based [7]. therefore, in this research study open pans evaporation (us class a, australian pan and british tank) and empirical method (blaney criddle) have been analysed and compared with the cropwat model for estimation of eto for current period of 15-year (1996-2010) in auchi, edo-state, nigeria. 2. materials and methods 2.1. study area the study area comprises of auchi district, which is one of the centrally located district of etsako west lga with 2338.9 sq km geographical area. the topography of the study area is undulating in nature. according to survey of nigeria the latitude and longitude are 7.07o 04’00”n and 6.27o 16’00’e respectively, and it has an average elevation of 188 meters above mean sea level (wikipedia). in auchi, the season is warm, oppressive and overcast and the dry season is hot, muggy and partly cloudy. the recent population census of auchi shows that the community inhabits about 104,540 people. auchi has two distinct climatic seasons (wet and dry season). the wet season spread from april to october, while the dry season is from november to march [10]. in auchi, the average annual temperature is 25.9 °c and precipitation averages of 1389 mm. the precipitation varies 249 mm between the driest month and the wettest month. the variation in temperatures throughout the year is 3.8 °c. the driest month is january. there is 11 mm of precipitation in january. the greatest amount of precipitation occurs in september, with an average of 260 mm. the aerial view of auchi is shown in plate 1 and location map in figure 2 and figure 3. figure 4 shows the satellite imagery showing the existing built area of auchi. computed average climate data for three decades (30 years) for auchi is shown in table 1. figure-1. areal view of auchi, nigeria. source: ministry of lands, surveying and housing, edo state, 2008. asian review of environmental and earth sciences, 2020, 7(1): 26-34 28 © 2020 by the authors; licensee asian online journal publishing group figure-2. map of nigeria indicating etsako west local govt area and auchi. source: ministry of lands, surveying and housing, edo state, 2008. figure-3. base map of auchi, source: ministry of land & survey, benin city, 2017. asian review of environmental and earth sciences, 2020, 7(1): 26-34 29 © 2020 by the authors; licensee asian online journal publishing group figure-4. satellite imagery showing the existing built up area of auchi community edo-state. source: ministry of land & survey, benin city, 2017. 2.2. data collection in order to calculate reference evapotranspiration (eto), the respective daily climate data collected from nigeria meteorological agency from the time periods of 1995-2010. the climate data are as follows: i. maximum temperature ( oc). ii. minimum temperature (oc). iii. relative humidity (%). iv. wind speed (km/h). v. sunshine hour (hours). vi. precipitation (mm). vii. evaporation depth (mm). these data were used as input parameters in the estimation of reference evapotranspiration (eto) different estimation approaches. three pan evaporation methods (us class a, australia pan and british tank), empiricallybased method (blaney-criddle) and cropwat model (using inbuilt modified penman-moniteth equation) were applied to compute eto. the results generated from the pans evaporation and blaney-criddle were compared with the cropwat reference evapotranspiration (eto) estimation. table 1 shows a set of equations and expression used in estimating reference evapotranspiration (eto). table-1. methods of computation. s/no empirical equations methods of computation 1. etous = kp.epan etoaustralia = kp.epan etobritish = kp.epan evaporation pan 2. eto = p(0.46tmean+8.13) blaney – crriddle 3. eto = inbuilt in cropwat model fao – 56 penman-monteith source: allen, et al. [1]. where: eto – reference evapotranspiration (mm/day). rn – net radiation at crop surface (mjm2/day). g – soil heat flux density (mjm-2/day-1) t – the mean daily air temperature at 2m height (oc) u2 – the wind speed at 2m height (m/s-1) ea – the saturation vapor pressure (kpa) ed – the actual vapor pressure (kpa) (ea-ed) – the saturation vapor pressure deficit (kpa) the slope vapour pressure curve (kpaoc-1) r = the psychometric constant (kpaoc-1) tmean = the mean daily temperature (oc) p = percentage of sunshine hour kp = pan coefficient (us class a = 0.7; australia = 0.9 and british tank = 0.85) epan = evaporation depth (mm) 2.3. model validation prediction error statistics, the performance evaluation of the different method was undertaken by comparing the values obtained by cropwat equation by the following statistical method to obtain the prediction error [5]. the average bias (ab) of the evaluated methods was calculated using the equation (1). asian review of environmental and earth sciences, 2020, 7(1): 26-34 30 © 2020 by the authors; licensee asian online journal publishing group (1) where: o, is the reference evapotranspiration (eto) estimated by the considered method (mm day-1). n, is the total number of observations. p, is the simulated reference evapotranspiration the errors of the evaluated methods were calculated using equations (2-4). rmse = (2) mae = (3) the estimated standard error (ese) was calculated using the equation: ese = (4) 2.4. statistical analysis generated outputs were subjected to critical analysis using statistical metrics such as determination of correlation (r2), last significant deference (lsd), root mean square. package such as (ssps) and matset were applied to model the computed variable. 3. results and discussion 3.1. estimation of reference evapotranspiration (eto) the vales of reference evapotranspiration (eto) estimated from five approaches for 15-year (1996-2010) in auchi as shown in table 2-5. the estimated highest values (eto) was obtained from cropwat model, which the empirically-based blandey-criddle gave the least value for all the simulations. in table 2, eto value of 3.3 mm/day was estimated from cropwat model, while 2.0 mm/day was estimated using us class a pan and australia pan, british tank and blanley criddle produced eto values of 2.5 mm/day, 2.3 mm/day and 1.0 mm/day respectively. there is gradual decrease in the rate of evapotranspiration in the month of july, august, september and october. this period is classified as wet season in auchi and its environs. during this period, the region usually experiences reduction in temperature (minimum and maximum) which is the main driver of evapotranspiration. however, the rate of eto starts to raise from november to the beginning of june. this period is categorized as dry season with little rainfall depth and increase temperature. this trend is continuous for the 15-year of experimental iterations. 3.2. model performance figures 5-12 show the variation of et0 calculated by different methods. the simulation is run for every month of the year. the monthly performance of each of the models (us class a (etous), australia pan (etoaus), british tank (etobt) and blaney criddle(etobc)) was compared with generated output from cropwat model. in evaluating monthly performance of the models against the cropwat software, etous, etoaus and etobt were estimated using the pan coefficient of 0.7, 0.9 and 0.85 respectively. mean temperature and percentage of sunshine hours were used to determine reference evapotranspiration for blaney criddle approach at auchi.there are differences between the monthly reference evapotranspiration eto from claas a pan, australia pan, british tank and blaney criddle model, and cropwat model. in the most of january, february march, november and december in 1996, cropwat software shown had the best performance over other models figure 5. evapotranspiration values were highly underestimated using etobc and etous, however better estimation was obtained in etoaus figure 5. this indicates that it is only cropwat model that could effectively capture the increase in the minimum and maximum during the dry season. however, all the eto estimation models were to perform better during the wet season (mayoctober) except cropwat model which produced higher reference evapotranspiration figure 5. this observation is applicable to the eto estimations for the current period’s 1997 and 1998 as depicted in figure 6-7. as shown in figure 8, in auchi for 1999, cropwat and blandey-criddle models provided a good estimate of eto values of 3.4 mm/day and 1.1 mm/day in january , while 0.7 mm/day, 0.9 mm/day and 0.8 mm/day were estimated using us class a, australia pan and british tank respectively table 5. however, eto estimated from blandey-criddle is the lowest in november (0.6 mm/day) and december (0.5 mm/day), while the three open evaporation pans (class a, australia and british) produced higher eto values of 1.8 mm/day, 2.3 mm/day and 2,1 mm/day and cropwat model simulated highest value of 3.4 mm/day in november and 3.2 mm/day in december respectively table 5 and figure 8. these results could be due to higher wind speed, sunshine and the increase in minimum and maximum temperature. estimation of reference evapotranspiration with the use of cropwat model using average climate (minimum and maximum temperature, sunshine hour, relative humidity, wind speed) data in auchi, showed variations in monthly estimated eto using cropwat model and other models (us class a, australia and british tank). significant underestimation of eto throughout the year (wet and dry) was obtained in all the models except cropwat software which produced realistic estimate of eto during the dry season and overestimated during the wet season. in order to compute accurate and precise crop water requirement (etc) which is the product of reference evapotranspiration (eto) and crop coefficient (kc), great caution should be applied should be applied in selecting most appropriate approach of estimating of eto for different seasons. if the eto is underestimated, this leads to incorrect estimation of crop water requirement and poor irrigation scheduling system. however, over estimation of eto will create incorrect variable and if this value is used to compute crop water requirement (etc), it can lead to under-irrigation. generally, accurate estimation of reference evapotranspiration (eto) is imperative to developing sound and sustainable water resources management mostly in arid regions. highest annual average bias values were obtained in 2001 with 2.8 mm, 2.8 mm, 2.8 mm and 2.2 mm, whereas lowest values were estimated in asian review of environmental and earth sciences, 2020, 7(1): 26-34 31 © 2020 by the authors; licensee asian online journal publishing group 1997 with biases of 1.7 mm, 1.3 mm, 1.5 mm and 2.6 mm for eto(us), eto(aus), eto(bt) and eto(bc) table 2-5. this observation is likely due to decrease in minimum temperature and increase in number of raining and rain depth in 1997. increase in other parameters influencing evapotranspiration such as temperature, wind speed, sunshine hours and solar radiation may be responsible for higher estimation of eto using cropwat software. 4. conclusion reference evapotranspiration (eto) was estimated using open pan (us class a, australia pan, and british tank) and empirically-based approach (blane-criddle) using 15-year baseline climate parameters. the output of each of the approach was compared with the cropwat model. the result of the analysis shows that the open pan method (eto us, eto aus and eto bt) underestimated reference evapotranspiration during the dry season, while the cropwat model performs better. blaney criddle (bc) estimates better evapotranspiration values in the dry season than the open pan approach. open pan and blaney criddle (bc) models give more accurate estimate of reference evapotranspiration (eto) than cropwat model during the wet season. this observation indicates weather-sensitivity of different models for estimating reference evapotranspiration (eto). calibration of reference evapotranspiration (eto) measured from the open pans and blaney criddle in comparison to cropwat model were estimated. generally, application of more than one models is very important in estimating reference evapotranspiration (eto) for better estimation of crop water requirement and irrigation scheduling. references [1] r. l. allen, l. a. pereira, d. raes, and m. smith, "crop evapotranspiration guidelines for computing crop water requirements. fao irrigation and drainage paper no. 56," food and agriculture organization, vol. 13, pp. 98-123, 2009. [2] r. g. allen, w. o. pruitt, j. wright, t. a. howell, and f. ventura, "a recommendation on standardized surface resistance for hourly calculation of reference eto by the fao56 penman–monteith method," agricultural water management, vol. 81, pp. 1-22, 2006.available at: https://doi.org/10.1016/j.agwat.2005.03.007. [3] p. w. d. burnett, "water resources of kerala’ public work department. kerala," resources newsletter, vol. 127, pp. 16-18, 2007. [4] fao, "state of the world’s forests. retrieved from: ftp.fao.org/docrep/fao/005/y7581," 2003. [5] r. g. allen, l. pereira, d. raes, and m. smith, "crop evapotranspiration (guidelines for computing crop water requirements)," irrigation and drainage, paper no. 56 fao, rome1998. [6] a. patel, r. sharda, s. patel, and p. meena, "reference evapotranspiration estimation using cropwat model at ludhiana district (punjab)," international journal of science, environment and technology, vol. 6, pp. 620-629, 2017. [7] j. doorenbos and w. o. pruitt, "crop water requirements (land and water development division)," irrigation and drainage paper no. 24. fao, rome, 1977. [8] i. watson and a. d. burnett, hydrology: an environmental approach. boca raton, fl: crc press, 1995. [9] c. w. thornthwaite, "an approach towards a rational classification of climate," geogr revue, p. 38, 1948. [10] y. olotu, o. i. galadima, and l. o. alumi, "climate change on discharge and sedimentation of river awara," nigeria. article, vol. 90, pp. 2-15, 2010. table-2. estimated reference evapotranspiration (eto) using four approaches in 1996. months eto (us) eto (aus) eto (bt) eto (bc) eto (cropwat) jan 2.0 2.5 2.3 1.0 3.3 feb 2.0 2.5 2.3 0.7 3.6 march 2.2 2.9 2.6 0.7 3.8 april 2.0 2.6 2.4 0.6 3.5 may 1.8 2.3 2.1 1.0 3.7 june 2.0 2.6 2.4 0.9 3.3 july 0.4 0.5 0.4 0.6 3.9 august 0.9 1.2 1.1 0.6 3.0 sept 0.7 0.9 0.8 0.6 3.1 october 0.8 1.0 0.9 0.8 3.3 nov 1.7 2.2 1.9 1.2 3.6 dec 1.9 2.5 2.3 1.2 3.4 source: field study, 2016. table-3. estimated reference evapotranspiration (eto) using four approaches in 1997. months eto (us) eto (aus) eto (bt) eto (bc) eto (cropwat) jan 2.0 2.6 2.4 1.1 3.7 feb 2.2 2.7 2.4 1.0 3.8 march 2.0 2.5 2.5 0.8 3.5 april 2.0 2.4 2.3 0.5 3.7 may 1.9 2.5 2.2 0.9 3.3 june 2.0 0.5 2.3 0.5 2.8 july 0.4 1.3 2.4 0.5 2.8 august 0.5 1.1 1.1 0.6 2.8 sept 0.8 1.7 1.0 0.6 2.9 october 0.9 2.3 1.1 0.8 3.1 nov 1.8 2.3 2.0 1.0 3.4 dec 2.0 2.6 2.4 0.5 3.4 source: field study, 2016. asian review of environmental and earth sciences, 2020, 7(1): 26-34 32 © 2020 by the authors; licensee asian online journal publishing group table-4. estimated reference evapotranspiration (eto) using four approaches in 1998. months eto (us) eto (aus) eto (bt) eto (bc) eto (cropwat) jan 1.3 1.6 1.5 1.0 3.3 feb 1.5 1.9 1.7 1.1 3.3 march 1.4 1.8 1.6 0.8 3.6 april 1.2 2.5 1.4 1.0 3.4 may 0.9 1.2 1.1 0.9 3.6 june 0.7 0.9 0.8 0.6 3.2 july 0.5 0.6 0.6 0.6 2.8 august 0.6 1.7 0.7 0.6 2.8 sept 0.5 0.6 0.6 0.8 3.3 october 0.7 0.9 0.8 0.6 3.2 nov 1.1 1.4 1.2 0.6 3.5 dec 1.0 1.5 1.2 0.6 3.4 source: field study, 2016. table-5. estimated reference evapotranspiration (eto) using four approaches in 1999. months eto (us) eto (aus) eto (bt) eto (bc) eto (cropwat) jan 0.7 0.9 0.8 2.0 3.4 feb 0.8 1.0 0.9 1.1 3.1 march 1.1 1.4 1.2 1.0 3.6 april 0.8 1.1 1.0 0.8 3.5 may 0.6 0.6 0.7 1.0 3.6 june 0.7 0.9 0.8 0.9 3.3 july 0.5 0.6 0.6 0.6 2.8 august 0.6 1.7 0.7 0.6 2.9 sept 0.4 0.5 0.5 0.6 2.9 october 0.5 0.6 0.6 0.8 3.1 nov 1.1 1.4 1.2 0.6 3.4 dec 1.8 2.3 2.1 0.5 3.2 source: field study, 2016. figure-5. variation of of references evapotranspiration (eto) estimated from five methods in 1996. source: field study, 2016. figure-6. variation of of references evapotranspiration (eto) estimated from five methods in 1997. source: field study, 2016. asian review of environmental and earth sciences, 2020, 7(1): 26-34 33 © 2020 by the authors; licensee asian online journal publishing group figure-7. variation of references evapotranspiration (eto) estimated from five approaches. source: field study, 2016. figure-8. variation of of references evapotranspiration (eto) estimated from five approaches in 1999. source: field study, 2016. figure-9. variation of reference evapotranspiration (eto) estimated from five approaches in 2000. source: field study, 2016. figure-10.variation of of references evapotranspiration (eto) estimated from five approaches in 2001. source: field study, 2016. asian review of environmental and earth sciences, 2020, 7(1): 26-34 34 © 2020 by the authors; licensee asian online journal publishing group figure-11.variation of of references evapotranspiration (eto) estimated from five approaches in 2002. source: field study, 2016. figure-12. variation of of references evapotranspiration (eto) estimated from five approaches in 2003. source: field study, 2016. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences vol. 4, no. 1, 28-35, 2017 issn(e) 2313-8173 / issn(p)2518-0134 doi: 10.20448/journal.506.2017.41.28.35 28 estimating hydraulic properties of alluvial sand aquifer in motloutse river course, eastern botswana edwin ok1 alemaw bf2 laletsang k3 tafesse nt4  ( corresponding author) 1aqualogic (pty) ltd, gaborone, botswana, 2,3,4department of geology, university of botswana, gaborone, botswana abstract a single layered alluvial aquifer in botswana along the motloutse river catchment was studied to estimate its hydraulic properties. ground penetrating radar survey (gpr) was used to determine the thickness and porosity of the aquifer. specific yield of the aquifer was determined in the laboratory. the hydraulic conductivity of the riverbed sediments were estimated using the alyamani-sen empirical formula and the hydraulic conductivity of the river bank sediment was measured using the slug test. geologically, the area is consists of alluvial deposits overlying granite, which is the bed rock of the area. the geophysical survey, gpr, provided information on the range of the thickness of the alluvium (9 – 12m) and also the porosity of the sediments (40%). the laboratory test resulted in an average specific yield of 13.68% for the riverbed sediments and 8.84% for the river bank sediments. a slug test performed in the riverbank yielded estimates of hydraulic conductivity of 26.43m/day. an average hydraulic conductivity value of 160m/day for the riverbed sediments was determined using the alyamani-sen formula. this difference in the hydraulic properties of the riverbed and the riverbank sediments is likely to be a result of sediment heterogeneity as more fine grained sediments is found together with sand in the riverbank sediments. these combined hydraulic properties estimation using empirical formulas, geophysical survey, laboratory tests, and the slug test highly improved the understanding of the hydrologic properties of the single layered alluvial aquifer system in the motloutse river catchment. in the same area, groundwater resource modelling can be done using these aquifer parameters to determine the groundwater potential of the aquifer. keywords: alluvial aquifer, botswana, groundwater, hydraulic properties, motloutse river. citation | edwin ok; alemaw bf; laletsang k; tafesse nt (2017). estimating hydraulic properties of alluvial sand aquifer in motloutse river course, eastern botswana. asian review of environmental and earth sciences, 4(1): 28-35. history: received: 2 october 2017 revised: 6 december 2017 accepted: 11 december 2017 published: 14 december 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: the research work presented in this paper is sponsored by the university of botswana through office of research and development (ord). authors highly appreciate the financial assistance. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 29 2. methodology ..................................................................................................................................................................................... 29 3. results and discussions .................................................................................................................................................................. 32 4. conclusions ....................................................................................................................................................................................... 35 references .............................................................................................................................................................................................. 35 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=edwin ok https://orcid.org/orcid-search/quick-search?searchquery=alemaw bf https://orcid.org/orcid-search/quick-search?searchquery=laletsang k https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt asian review of environmental and earth sciences, 2017, 4(1): 28-35 29 1. introduction 1.1. general botswana is a semi-arid country with subdued topography, low surface runoff, and low groundwater recharge [1]. rural communities in botswana rely on agriculture for income, food and employment. the farming activity is sustained with rain-fed agriculture, which is affected by harsh climatic conditions. however, in eastern botswana, ephemeral sand rivers constitute a large source of groundwater [1, 2] which may be useful for irrigation. rainfall over the motloutse catchment area occurs in summer, and mean monthly evaporation exceeds mean monthly rainfall. communities within the river catchment depend on the river to sustain their agricultural needs. the geology of the area is consists of alluvial deposits overlying the granite, which is the bed rock of the area. the alluvial deposits or the motloutse sand river consists mainly of sand and gravel at variable depth, with coarse sand along the middle of the river and silt and clay occurring adjacent to river banks. the alluvial sediments in the flood plain are a source of water for the different needs of the community during the dry months. the aquifer is unconfined and receives recharge from the river flow and direct percolation. the hydrogeological characteristics of the motloutse alluvial aquifers are not documented [3] and effective water management, water storage planning and management are hampered by the lack of knowledge of their storage properties. this complicated by the varying thickness of the river sand, river morphology, and the increasing demand from the community. groundwater potential of the motloutse alluvial aquifer was investigated to support irrigation development and to improve the livelihoods of the communal farmers. the main objective of this work was to determine the different hydraulic properties of the motloutse alluvial aquifer on a one kilometre stretch of the motloutse river that can be used to quantify the groundwater resource potential in the area. 1.2. location the study area is located in eastern botswana near the mmadinare, tobane and bobonong villages (figure 1). it lays along the motloutse river, downstream of the letsibogo dam in the motloutse catchment, a sub-catchment of the limpopo basin. four countries in south-eastern africa share the limpopo basin: botswana, mozambique, south africa and zimbabwe. the majority of the motloutse catchment is characterised by flat savannah and, although devoid of major mountains, few hills are present in the catchment. it is ~20, 000 km2 in area and the motloutse river has a stream length of ~250 km in an east-west trend with the tributaries trending north-south ( figure 1). the main land use is subsistence farming with vast areas of land used as grazing growing crops. figure-1. location map of study area within southern africa and limpopo basin. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. 2. methodology ground penetrating radar (gpr) was used to map the depth to bedrock across the motloutse river, and indirectly the thickness of the sand within the channel. ground penetrating radar (gpr) is a geophysical method used to detect and map shallow subsurface features with high precision. it is similar in many respects to seismic reflection and refraction methods but it utilizes electromagnetic waves to reflect, refract, and diffract from subsurface targets instead of acoustic waves. asian review of environmental and earth sciences, 2017, 4(1): 28-35 30 the choice of location for the gpr profiles was based on the width, access, and slope of the riverbed. five (5) radar transacts across the motloutse river were recorded near tobane village (figure 2). these profiles were trending north-south and their length was determined by the river width ranging between100 and 135m. these transacts were spaced at 250m as illustrated in figure 2. along each of these profiles, elevations and coordinates were captured with trimble differential global positioning system (dgps) from the two (2) banks and along the middle section of the river for topographic corrections. the radar grid was confined to the channel width and not extended to the alluvial plains due to riverine vegetation that impedes access. optimum offset gpr reflection profiles were recorded along the profiles using a 50 mhz ramactm-mala geosciencetmgpr system with unshielded antennae. the antennae’s were kept at a constant separation of 2 m with a wooden raft. the antennas were orientated parallel to each other and perpendicular to the profile. to improve the signal to noise ratio every trace was vertically stacked sixteen (16) times. a hip chain with a bio-degradable thread was used to measure the profile length. the velocity of the profiles was recorded directly from the display device at 59m/µs. this value was be used to calibrate the processing software packages so that correct depths are determined. figure-2. location of gpr profiles and simplified plan view of the gpr survey. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. apart from the basic detection and mapping of subsurface geological features, gpr measurements can also be used to determine hydraulic properties of porous materials such as porosity, hydraulic conductivity, water saturation, etc. as has been shown in numerous previous investigations [4-9]. this is because related parameters such as dielectric constant and radar wave velocity are highly dependent on moisture content. in low loss medium (soils with low salinity and clay content) which is expected of river sand, the velocity (v) of the soil can be related to the dielectric constant by eq. 1 [10]. √ where c is the electromagnetic wave velocity in free space, and k' is the real part of the dielectric constant of the medium. velocity of 0.06m/ns that was read from the ramac mala geoscience display device which is also in conjunction with velocity for unsaturated sands was used and dielectric constants read from tables of dielectric constants for different materials [10, 11]. topp, et al. [7] using various soil samples found out that the real part of the dielectric constant was increasingly sensitive to volumetric water content, while also weakly sensitive to soil type and density and derived an empirical relationship (eq. 2) between apparent dielectric constant and volumetric water content: (2) where is the volumetric water content (the ratio of water volume to total sample volume). for low-loss materials ka ≈ k' where ka is the apparent dielectric constant and k'is the real part of the dielectric constant of the medium as it was defined in eq. 1. the water content ( ) equals the product of porosity ( ) and water saturation ( ) as in eq. 3 [5]. (3) where water saturation ( ) is the ratio of water volume to pore volume. however in water saturated soils the water content ( ) is a measure of porosity ( ), that is, ≈ . after ground penetrating radar survey, as a ground-truth control the motloutse river was augered at the sites where gpr data was collected. the riverbed was augered to a depth of 3.5m and the water was striked at a depth of 0.6m. augering to a further depth was not possible because the auger tool itself nearly got damaged, any further asian review of environmental and earth sciences, 2017, 4(1): 28-35 31 twist it would have broken. it was initially a pit was dug to a depth of about 2m using shovels and from there the auger was installed but the water that was collected in the pit was too much and hindered the augering process.3.5 m is not the exact thickness; the sand is much thicker than this amount. however, the thickness of sand is not uniform throughout the area where this measurement was conducted; the riverbed in some areas had deeper sand thicknesses and the augering was done in areas were the sand is thinner. the specific yield of the sandy aquifer was determined in the engineering geology laboratory of the department of geology in the university of botswana. specific yield is the ratio of water that can be drained by gravity from a saturated sample to the total volume of sediment in laboratory terms. freeze and cherry [12] defined it as the amount of water released from storage of an unconfined aquifer per unit surface area of the aquifer per unit decline of the water table. specific yield is given by eq. 4 after meinzer [13]. (4) where sy is specific yield, vd is volume drained from aquifer by gravity; and, vt is total volume. nine sand samples representative of the aquifer material were collected both from the riverbed and at the riverbanks for this purpose. out of these samples 5 of them were from the riverbed and the remaining four were from the riverbank (figure 3). samples were obtained from a depth of 2 and 3 m on the aquifer to avoid surface sampling, this is due to some physical and biological processes such as surface shrinkage, silty layers or lenses referred to as “planosols” that result in varying aquifer properties [14]. figure-3. location of aquifer material sampling sites in relation to gpr profiles. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. the hydraulic conductivity of the sediments was determined using an empirical formula and the slug-test method. for the riverbed, the hydraulic conductivity of the sandy aquifer was determined by empirical formula using the collected riverbed samples. the method used in this study is the alyamani-senempirical formula, which is given by alyamani and sen [15] as [ ] (5) where k is hydraulic conductivity (m/day), i0 is intercept (in mm) of the line formed by d50 and d10 with the grain-size axis, or simply the x-axis, d50 is median grain diameter (mm), and, d10 is effective grain diameter (mm). the alyamani and sen [15] formula was chosen because the equation considers both sediment grain sizes as well as the sorting characteristics. grain size analysis of the sediment was done in accordance to the astm d-422 or d2487 standard (american society for testing and materials) and unified soil classification system (uscs) as both are the most widely used technical standards. to determine the hydraulic conductivity of the riverbank sediments an in situ measurement was carried out using slug test. the test was carried out as follows.  a one metre pvc tube was pressed vertically into the aquifer until the slots in the tube were submerged under the water level;  the tube was submerged up to 24cm under the water level with 76cm remaining over the water table;  sufficient water was then poured into the tube until it reached top of the tube and this is to ensure the saturation of a large area of the aquifer around and below place of measurement; and,  time taken for the head to fall or attain initial water level was recorded. k from slug test was estimated using eq. 6 after masvopo, et al. [16] as follows; [ ] [ ] (6) http://www.astm.org/ http://www.astm.org/ asian review of environmental and earth sciences, 2017, 4(1): 28-35 32 where k is hydraulic conductivity (m/day), q is discharge (m3/day), a is cross sectional area of soil sample (m2), i is hydraulic gradient, r is radius of tube (m), t is time taken for water column to attain initial water level (day), and, h is length of pvc tube under the water level (m). 3. results and discussions 3.1. geophysics even though five radar transacts were recorded and analyzed only two of them are presented here for the purpose of discussion. this radar transacts were the one that was recorded at the beginning (figure 4) and in the end (figure 5) of the measurements; recorded in the downstream and upstream side of the river, respectively, or at the site from where the soil samples s1-1 and s1-5 (figure 3) were collected. these figures show both the raw radar images (figure 4a and figure 5a) and the migrated radar images (figure 4b and figure 5b) in these sites. in the figure 4b the migration was accomplished using a dc permitivity value of 65 (dielectric constant) whereas in figure 5b migration was done with a dielectric constant of 70. the first reflections in all the figures are a characteristic airwave and groundwave, respectively. this is caused by the direct electromagnetic wave interaction with air, and is represented by black, continuous reflection amplitudes that form a very straight, horizontal solid bar as on in figure 4a and 5a. below the groundwave reflection is the unsaturated zone of the sediment, interpreted as the unsaturated sand. the next two or three prominent (three in figure 4a and 2 in figure 5a), high amplitude reflections that are easily identified and traced across all the radar records are interpreted as the water table. this is because in sediments, the water content primarily causes the changes in dielectric properties [17]. a change from dry to wet sand results in a change from a threephase system (air, water and sediment) to a twophase system (water and sediment) in which other factors apart from porosity control the dielectric properties [18]. further down the profile after the water table, the next reflections are generally weak in all the radargrams (figure 4a and figure 5a) but follow a similar trend to it. since attenuation is strong below this point this could be indicative of groundwater. conyers [19] affirms that the water content often increases with depth resulting in attenuation of radar waves with increasing depth. these stronger groundwater reflectors could be related to sediments that have a larger sand fraction at depths: suggesting to be bounding surfaces between two sand layers of different periods of deposition. below these reflections, no further reflections are observed in wiggle form in all radargrams; suggesting a marked change in reflective characteristics. this is interpreted as an interface between the sediments and the bedrock because at the resolution used, radar signals will not be able to penetrate the granite bedrock. however, this not at achieved at the same depth in all the profiles. as shown in figure 4b on the migrated image that the sand thickness reaches up 12 m whereas in the upstream side the sand thickness is less and reaches up 9 m (figure 5b). the gpr results obtained match or corroborate with the augering findings. as earlier noted from augering observation the sand was much thicker than 3.5 m. based on water strikes the water levels seem to be a bit shallower from those in gpr interpretations because at the time of augering it was already rainy season. figure-4. a) the raw radar image before migration; b) the migrated radar image. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. asian review of environmental and earth sciences, 2017, 4(1): 28-35 33 figure-5. a) the raw radar image before migration; b) the migrated radar image. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. 3.2. aquifer parameters porosity porosity was found to be 40% determined from the ground penetrating radar. this high porosity value is expected for river sands and for clays and silts from riverbank samples. it is also within the range of values reported in the literature for such materials. representative porosity values for various unconsolidated sedimentary materials, sedimentary rocks and crystalline reported by morris and johnson [20] stated that the range of porosity for coarse sand to clay is from 31 % to 57%. according to freeze and cherry [12] the range of porosity values for sand, silt and clay is from 25% to 70%. nord [21] obtained a porosity of 35% for motloutse river sand. specific yield table-1. computation of specific yield. sample id mass of beaker + saturated sand (g) mass of empty beaker (g) mass of saturated sand (g) mass of beaker +drained sand (g) mass of drained sand (g) mass of water (g) specific yield s1-1 476.40 33.80 442.6 464.24 430.44 12.16 7.49 s1-2 521.07 32.65 488.42 486.65 454.00 34.42 20.09 s1-3 494.06 32.65 461.41 460.78 428.13 33.28 20.60 s1-4 452.32 33.80 418.52 434.04 400.24 18.28 12.10 s1-5 480.35 33.80 446.55 467.05 433.25 13.3 8.14 s2-1 527.38 32.65 494.73 501.62 468.97 25.76 14.56 s2-2 476.96 33.80 443.16 464.35 430.55 12.61 7.76 s2-3 501.43 33.80 467.63 476.25 442.45 25.18 5.69 s2-4 485.96 32.65 453.31 455.01 422.36 30.95 7.33 source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. specific gravity of sand was taken as 2.65 because river sand has the main component as quartz and this value is applicable to sands that are not packed. an average specific yield of 13.68% for samples collected only on the riverbed was found (table 1), which is low for this river section as compared to that derived by nord [21] of 20% and very low for a typical sand formation which has a range of 21 to 27% [22]. an average specific yield for the river bank sediments is much lower than the riverbed one. however, both these values will give a conservative estimate of the groundwater resource. hydraulic conductivity in the analysed sediment samples, the grain size ranges from 0.008mm to 10 mm in diameter as can be seen in figure 6, which is a very wide range attesting to the poorly graded sand and the heterogeneous nature of the asian review of environmental and earth sciences, 2017, 4(1): 28-35 34 aquifer. the median (d50) and effective grain diameter (d10) are 1.6 and 0.4, respectively. according to the unified soil classification system [22] the motloutse sediment is poorly graded sand with gravel or gravelly sand. table-2. uscs classification of aquifer material samples. sample id s1-1 s1-2 s1-3 s1-4 s1-5 per cent fines 0.14 0.1 0.1 0.3 0.2 per cent sand 95.8 81.8 79.1 97.3 81.1 per cent gravel 3 7.7 16.3 1.4 18.7 cc 1.16 0.89 0.98 0.89 0.88 cu 3.2 4.5 4.7 3.2 4.3 uscs classification sp sp sp sp sp source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. wherecc is coefficient of curvature; cu is coefficient of uniformity; and, sp is poorly graded sand. coeffıcient of curvature, cc, is the ratio (d30)2/(d10 x d60),where d60, d30, and d10 are the particle sizes corresponding to 60, 30, and 10 % finer on the cumulative particle-size distribution curve, respectively. coeffıcient of uniformity, cu, is the ratio d60/d10, where d60 and d10 are the particle diameters corresponding to 60 and 10 % finer on the cumulative particle-size distribution curve, respectively. figure-6. grain size distribution curve of the motloutse sediments. source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. hydraulic conductivity using alyamani-sen formula table-3. computed hydraulic conductivity values using alyamani-sen formula. sample id d10 d30 d60 cu cc io hydraulic conductivity (m/day) s1-1 0.3 0.7 1.1 3.2 1.1 0.3 113.9 s1-2 0.4 0.9 2.1 4.5 0.9 0.3 144.8 s1-3 0.7 1.6 3.4 4.7 0.9 0.5 443.1 s1-4 0.3 0.5 0.9 3.2 0.8 0.3 89.6 s1-5 0.4 0.9 2.1 4.3 0.8 0.3 161.9 k mean = 160.4 source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. an average hydraulic conductivity value of 160m/day (1.856 x 10-3m/sec) for gravelly sand was determined using alyamani-sen formula. this value is within a reasonable range of values of hydraulic conductivity for gravelly sand. representative values of hydraulic conductivity for various unconsolidated sedimentary materials, sedimentary rocks, igneous and metamorphic rocks complied by freeze and cherry [12] shows that the values of hydraulic conductivity for gravelly sand is ranging from 1.157 x 10-4 to 1.157 x 10-1 m/sec. hydraulic conductivity from slug test table-4. hydraulic conductivity from slug test. sample id radius(m) h(m) t(s) h(m)2 k(m/s) k(m/d) s2-1 0.01 0.76 29 0.24 0.000166776 14.40947992 s2-2 0.01 0.76 2000 0.24 0.000378298 32.68491787 s2-3 0.01 0.76 3500 0.24 0.000534835 46.20971147 s2-4 0.01 0.76 6000 0.24 0.000143613 12.40816327 k mean 26.43 source: edwin o.k., m.sc. thesis, university of botswana, gaborone, botswana, 2016. asian review of environmental and earth sciences, 2017, 4(1): 28-35 35 slug test produced a mean value of 26.43m/day (3.059 x 10-4m/sec) for the riverbank sediments. this value is also within a reasonable range of values of hydraulic conductivity for sand that comprises of a lot of silt and clay. 4. conclusions a one-layered aquifer, riverbank alluvial and riverbed deposits, was studied to characterize their hydraulic properties. geologically the area is consisting of alluvial deposits overlying the granite, which is the bed rock of the area. the alluvial deposits or the motloutse sand river consists mainly of sand and gravel at variable depth, with coarse sand along the middle of the river and silt and clay banks occurring adjacent to river banks. geophysics method have been applied to resolve depth to bedrock using gpr, and it is found that the range of the thickness of the alluvium varies from 9 – 12m, and gpr also provided reasonable estimates of porosity of the sediments, which is 40%. the grain size analyses of the riverbed sediments revealed that the motloutse sediments are poorly graded gravelly sand. the laboratory test resulted in an average specific yield of 13.68% for the riverbed sediments and 8.84% for the river bank sediments. a slug test performed in the riverbank yielded estimates of hydraulic conductivity of 26.43m/day (3.059 x 10-4m/sec). an average hydraulic conductivity value of 160m/day (1.856 x 103m/sec) for gravelly sand was determined using alyamani-sen formula. this difference in hydraulic properties of the riverbed sediments and the riverbank sediments is likely a result of sediment heterogeneity as more fine grain sediments are found together with sand in the riverbank sediments. these combined hydraulic properties estimation using empirical formula, geophysical survey, laboratory test and slug test greatly enhanced the understanding of the hydrologic properties of the single layered alluvial aquifer system in the motloutse river catchment. for those who want to continue further studies in the studied area, these determined aquifer parameters can be used to determine the groundwater potential of the aquifer using groundwater modeling techniques. references [1] government of botswana national water master plan review, "gaborone, ministry of mineral, energy & water resources, department of water affairs," vol. 4, p. 30, 2006. [2] r. herbert, j. barker, j. davies, and o. katai, "exploiting groundwater from sand rivers in botswana using collector wells," in proc. 30th /international geology congress, 1997, pp. 235-257. [3] d. love, w. hamer de, r. owen, m. booij, s. uhlenbrook, a. hoekstra, and p. zaag van der, "case studies of groundwater: surface water interactions and scale relationships in small alluvial aquifers," presented at the 8th waternet/warfsa/gwp-sa annual symposium, lusaka, zambia, 2007. [4] j. a. huisman, c. sperl, w. bouten, and j. m. verstraten, "soil water content measurements at different scales: accuracy of time domain reflectometry and ground-penetrating radar," journal of hydrology, vol. 245, pp. 48– 58, 2001. view at google scholar | view at publisher [5] a. turesson, "water content and porosity estimated from ground-penetrating radar and resistivity," journal of applied geophysics, vol. 58, pp. 99-111, 2006. view at google scholar | view at publisher [6] j. a. doolittle, b. jenkinson, d. hopkins, m. ulmer, and w. tuttle, "hydropedological investigations with ground penetrating radar (gpr): estimating water-table depths and local ground-water flow pattern in areas of coarse-textured soils," geoderma, vol. 131, pp. 317-329, 2006. view at google scholar | view at publisher [7] g. c. topp, j. l. davis, and a. p. annan, "electromagnetic determination of soil water content: measurements in coaxial transmission lines," water resources research, vol. 16, pp. 574-582, 1980. view at google scholar | view at publisher [8] i. lunt, s. hubbard, and y. rubin, "soil moisture content estimation using ground-penetrating radar reflection data," journal of hydrology, vol. 307, pp. 254--269, 2005. view at google scholar | view at publisher [9] b. schmalz and b. lennartz, "analyses of soil water content variations and gpr attribute distributions," journal of hydrology, vol. 267, pp. 217226, 2002. view at google scholar | view at publisher [10] j. l. davis and a. p. annan, "ground penetrating radar for high resolution mapping of soil and rock stratigraphy," geophysical prospecting, vol. 37, pp. 531–551, 1989. [11] d. j. daniels, ground penetrating radar, 2nd ed. london, uk: the institute of electrical engineers, 2004. [12] r. a. freeze and j. a. cherry, groundwater. englewood cliffs, new jersey: prentice hall, 1979. [13] o. e. meinzer, "the occurrence of groundwater in the united states, with a discussion of principles," u.s. geol. survey, water supply paper, vol. 489, p. 321, 1923. [14] r. j. oosterbaan and h. j. nijland, determining the saturated hydraulic conductivity. chapter 12 in: h.p.ritzema (ed.), drainage principles and applications, 2nd ed. wageningen, the netherlands: international institute for land reclamation and improvement ( ilri), publication 16, 1994. [15] m. s. alyamani and z. sen, "determination of hydraulic conductivity from grain-size distribution curves," ground water, vol. 31, pp. 551-555, 1993. view at google scholar | view at publisher [16] t. masvopo, d. love, and h. makurira, "evaluation of the groundwater potential of the malala alluvial aquifer, lower mzingwane river, zimbabwe," presented at the waternet/warfsa/gwp-sa symposium, abstract vo.9th, johannesburg, 2008. [17] a. p. annan, "practical processing of gpr data," in proceedings of the second government workshop on ground-penetrating radar, columbus, ohio, 1993. [18] r. van dam and w. schlager, "identifying causes of ground-penetrating radar reflections using time-domain reflectometry and sedimentological analyses," sedimentology, vol. 47, pp. 435–449, 2000. [19] l. b. conyers, ground penetrating radar for archaeology. lanham: altamira press, 2004. [20] d. a. morris and a. i. johnson, "summary of hydrologic and physical properties of rock and soil materials as analyzed by the hydrologic laboratory of the u.s. geological survey. u.s. geological survey water-supply paper no.1839-d," p. 42, 1967. [21] m. nord, sand rivers of botswana: phase 2; department of water affairs, government of botswana, 1985. [22] r. d. holtz and w. d. kovacs, an introduction to geotechnical engineering: prentice hall, 1981. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=soil%20water%20content%20measurements%20at%20different%20scales:%20accuracy%20of%20time%20domain%20reflectometry%20and%20ground-penetrating%20radar http://dx.doi.org/10.1016/s0022-1694(01)00336-5 http://dx.doi.org/10.1016/s0022-1694(01)00336-5 https://scholar.google.com/scholar?hl=en&q=water%20content%20and%20porosity%20estimated%20from%20ground-penetrating%20radar%20and%20resistivity http://dx.doi.org/10.1016/j.jappgeo.2005.04.004 https://scholar.google.com/scholar?hl=en&q=hydropedological%20investigations%20with%20ground%20penetrating%20radar%20(gpr):%20estimating%20water-table%20depths%20and%20local%20ground-water%20flow%20pattern%20in%20areas%20of%20coarse-textured%20soils http://dx.doi.org/10.1016/j.geoderma.2005.03.027 https://scholar.google.com/scholar?hl=en&q=electromagnetic%20determination%20of%20soil%20water%20content:%20measurements%20in%20coaxial%20transmission%20lines http://dx.doi.org/10.1029/wr016i003p00574 https://scholar.google.com/scholar?hl=en&q=soil%20moisture%20content%20estimation%20using%20ground-penetrating%20radar%20reflection%20data http://dx.doi.org/10.1016/j.jhydrol.2004.10.014 https://scholar.google.com/scholar?hl=en&q=analyses%20of%20soil%20water%20content%20variations%20and%20gpr%20attribute%20distributions http://dx.doi.org/10.1016/s0022-1694(02)00152-x https://scholar.google.com/scholar?hl=en&q=determination%20of%20hydraulic%20conductivity%20from%20grain-size%20distribution%20curves http://dx.doi.org/10.1111/j.1745-6584.1993.tb00587.x 18 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 18-25, 2020 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.18.25 © 2020 by the authors; licensee asian online journal publishing group pesticides and fertilizers use in parts of rivers niger and kaduna catchments, north central, nigeria idris, aliyu ja’agi1 yahaya, t. i.2 abubakar, a. s.3 jigam, a. a.4 ( corresponding author) 1,2,3department of geography, federal university of technology minna, niger state, nigeria. 4department of biochemistry, federal university of technology minna, niger state, nigeria. abstract pesticides and fertilizers use in parts of rivers niger and kaduna catchments, north central, nigeria was investigated. contamination of the rivers and their resources due to unsustainable use of pesticides and fertilizers by local farmers are a major problem in the study area. also, data from the study of pesticides and fertilizer use remain scanty and therefore needed. the objective is to find the opportunity for all stakeholders to improve on the overall environmental performance. extensive field survey was conducted using various participatory appraisals techniques involving key stakeholders in the area. collated data were analysed using descriptive statistical methods (frequency percentage). the results of findings identify unsustainable use of fertilizers and pesticides by farmers in the study area. it further shows respondents in the study area applied high rate of fertilizers and pesticides during farming activities which obviously improved crop yield but in turn lead to water quality degradation. virtually, majority of the farmers have little or no measures towards ensuring protection of water and biota from the potential danger of pesticides and fertilizers use in the study area. these attitudes discovered could lead to water quality degradation, biodiversity disruption and subsequent negative impact on economic development in the study area. in view of the above, it is recommended that visible and effective environmental management policies in respect of agrochemicals use in the study area be put in place to guarantee cleaner and healthier environment for all. keywords: fertilizers, pesticides, catchments, rivers, sediments, water quality, health, environment. citation | idris, aliyu ja’agi; yahaya, t. i.; abubakar, a. s.; jigam, a. a. (2019). pesticides and fertilizers use in parts of rivers niger and kaduna catchments, north central, nigeria. asian review of environmental and earth sciences, 7(1): 18-25. history: received: 28 october 2019 revised: 2 december 2019 accepted: 7 january 2020 published: 13 february 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 19 2. the study area ................................................................................................................................................................................. 19 3. materials and methods ................................................................................................................................................................... 20 4. results and discussion ................................................................................................................................................................... 20 5. conclusion and recommendations ............................................................................................................................................... 24 references .............................................................................................................................................................................................. 24 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.18.25&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 https://www.asianonlinejournals.com/index.php/arees/article/view/1316 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 asian review of environmental and earth sciences, 2020, 7(1): 18-25 19 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study has been able to established a background information on pesticides and fertilizers use attributable to water quality degradation which no other known researches have ever considered in the study area. this research contribution will serve as a baseline for further empirical researches in the area of laboratory analysis of water, sediment and biota in the study area. 1. introduction pest infestations, government subsidies, rapid population growth in addition to change in climate has resulted to a driving force for farmers to use more pesticides and fertilizers in agricultural activities [1]. fertilisers and pesticide are intended to facilitate plant growth and protections. although initially used to improve crop production. sequel to application of these chemical compounds on farm lands to achieve the essential mission to care for crops, they have been reported also to compromise water quality [1]. they move into the surrounding water bodies, therefore having a widespread effect on the physical, chemical and biological processes within aquatic ecosystems [2]. it is established that banned pesticides are still being imported illegally in to nigeria through porous borders [3]. the use of synthetic fertilizers and pesticides in many parts of the world are on the increase [4]. river niger catchment are arable land where people practice farming involving intense use of agrochemicals [5]. this practice can eventually cause degradation of water quality and disproportionate effect on the socio-economic wellbeing of the communities in the area. communities’ dependant on the resources from the river for livelihood and lack of enough research information about the area that represent risk of fertilizers and pesticides contamination informed the need for this study to guaranty socioeconomic sustainability. finding of this study is targeted at providing opportunity for relevant government authorities and all stakeholders in this sector to improve on overall environmental performance. 2. the study area the study area for the investigation is communities in parts of rivers niger and kaduna catchment areas, niger state which lies between longitude 3˚30'n and 7˚20'e and latitude 8˚22'n and 11˚30'n; located at the guinea savanah vegetation zone in the north central part of nigeria figure 1. rivers niger and kaduna catchments are arable land where people practice agricultural activities close to the rivers [6]; [5]. the study area was divided into zones according to agroecological factors. along river niger, the upper zone is from rabba village in mokwa local government area (lga), middle zone is at muregi and the lower zone is after muregi in mokwa lga down to baro village in agaie lga. study area along river kaduna was divided into two zones. upper zone is from wuya village in lavun lga and the lower zone from half way down to muregi. the major economic activities of the communities living around the area are agriculture and fishing. these are the leading sector in terms of employment, income earning and overall contribution to the socio-economic wellbeing of the people. the kaduna and niger river flood plains are many kilometers wide at the downstream of nupe basement boundary, two major streams yanko ikko, dumi, ebigi. all these empty their waters in to niger river [6]. figure-1. map of the study area showing parts of rivers niger and kaduna catchment, north central, nigeria. asian review of environmental and earth sciences, 2020, 7(1): 18-25 20 © 2020 by the authors; licensee asian online journal publishing group 3. materials and methods (a) primary data. the study was achieved through a prospective cross-sectional study in the study area. it utilizes primary data from structured questionnaires, scheduled interview, visual observations and ground photograph as described by banerjee, et al. [7]. (b) secondary data. secondary data were obtained from study area map, demographic data (population) and relevant literature materials to identify gaps and missing links in the existing body of knowledge. furthermore, information were sourced from standardized national and international documents relevant to agrochemical regulations and enforcement i.e. national gazetted regulations from national environmental standards and regulations enforcement agency, (nesrea), regulatory documents from national agency for food and drug administration and control (nafdac), national policy on environment, and other relevant documents. (c) data sampling. the number of farmers included in the study (participants) was determined using yamani's formula. this formula is concerned with applying a normal approximation with a confidence level of 95% and a limit of tolerance level (error level) of 5%. to this extent the sample size was determined by n = n 1.0 1+ne2 where: n = the sample size. n = population. e = the limit of tolerance (0.05) therefore, n = 30,229 = 30,229 = 30,229 = 30,229 1 + 30,229(0.05)2 1 + 30,229(0.0025) 1 + 75.5 76.5 n = 390 respondent. the study respondents were 395 and simple random sampling was used to distribute the questionnaires among the respondents who are mainly farmers in the study area. three hundred and ninety-five questionnaires were distributed and 350 were returned. questionnaires were administered following proper institutional and field validations. interviews schedules were directed to key informants which include experienced district officers, extension agents and agrochemical vendors in the study area. the respondents were approached by the study team. the objective of the study was explained to them following which consent were obtained from them. the questions include: sizes of farms, type of farming, types of crops grown, when are the planting seasons, pest and other problems, types and quantities of farm chemicals used on farms, consideration for label instructions, farmer’s knowledge and attitude towards agro-chemicals, where the farmers procure the agro-chemicals from, disposal of used cans, washing of applications tools and measures taken to conserve the river and use of the river water. this provides the opportunity for capturing the required information to achieve this objective. (d) statistical analysis. data obtained from administered questionnaire and interview schedules of farmers and key stakeholders in the area was analysed for pesticide and fertilizers use using descriptive statistical methods (frequency percentage) and then presented in tables and figures for clarity. 4. results and discussion 4.1. farming analysis as indicated in table 1, the hectare of land used by the respondents in the study area ranges from 2 to 15. upper zones ranked the highest in number of hectares of land used for farming with 142 respondents, lower zones ranked second with 122 respondents and middle zone ranked the least with 86 respondents. in 2 to 5 hectares’ ranges, upper zones ranked the highest with 69 respondents and middle zone ranked the least with 21 respondents. in 6 to 10 ranges, lower zones ranked the highest with 47 respondents and middle zone ranked the least with 20 respondents. in 11 to 15 ranges, middle zone ranked the highest with 45 respondents and lower zones ranked the least with 30 respondents. table-1. number of hectare of land used by the respondents in parts of rivers niger and kaduna catchment, north central, nigeria. options upper zones middle zone lower zones 2 – 5 69 19.7% 21 6.0% 45 12.9% 6 – 10 31 8.8% 20 5.7% 47 13.4% 11 – 15 42 12% 45 12.9% 30 8.6% total 142 40.5% 86 24.6% 122 34.9% the findings imply that majority of the respondents in all the zones were subsistence farmers since they used between 2 – 10 hectares of land in the study area. rice, maize, beans, groundnut, millet and melon are the mostly crops grown across the zones in the area. most of the farm lands have been in use for over 30 years. the farmers in the area also practiced crop rotation involving maize, beans, sorghum, melon and pepper. interview findings from experienced district officers, extension agents and agrochemical vendors corroborated all the submissions by the farmers in the study area. similar farming system have been reported around riverine areas in developing countries like kenya indicating majority of communities practicing subsistence farming [8]. 4.2. planting season as indicated in table 2, majority of the respondents affirmed that they plant most of their crops rainy seasons. rainy season ranked the highest with 274 respondents and dry season ranked the least with 76 respondents across the zones. the number of farmer involved in rainy season farming at the upper, middle and lower zones constitutes 30.5%, 18.6% and 29.1% respectively. those involved in dry season farming at upper, middle and lower zones constitutes 46%, 6% and 11.2% respectively. asian review of environmental and earth sciences, 2020, 7(1): 18-25 21 © 2020 by the authors; licensee asian online journal publishing group table-2. planting season in parts of rivers niger and kaduna catchment, north central, nigeria. options upper zone middle zone lower zone rainy season 107 30.5% 65 18.6% 102 29.1% dry season 16 4.6% 21 6% 39 11.2% total 123 35.1% 86 24.6% 141 40.3% this implies that majority of the respondents’ plant most of their crops during the rainy season and those that farm during the dry season farms vegetables, rice and sugarcane. the farmers were asked as to why they prefer rainy season farming and the response was due to abundant rain and availability of farming accessories at lower cost. those that adopt farming in both season gave the reasons that there are less pest infestations during dry season except bird attack which can easily be contained. the study also identified a number of farmers do plant some of their crop three times during rainy and dry seasons in a year. this crops include maize, rice sugarcane and vegetables. findings in this study also revealed almost all the farmers complained about the problems of pest infestations, weeds and late and early stoppage of rain. they further submitted that dependant on agrochemical has been the viable method adopted by them to minimize the effects of the challenges. interview findings also revealed that most farmers in the study area plant their crops in the rainy season do to abundant moisture. they also acknowledged farming activities in both season and presence of pest infestations during all seasons in the area. the planting season and cropping pattern identified in this study is in in line with the pattern in practice in northern nigeria [9]. 4.3. use of fertilizer and pesticides in farming as indicated in table 3, there were high use of pesticide and fertilizer in farming activities of the respondents in the study area. lower zones ranked the highest with use of pesticides and fertilizer (39.4%); upper zones ranked second with 33.5% and middle zone ranked the least with 24.5%. out of 100% of the respondents, 2.7% disaffirmed the use of pesticides and fertilizers in their farms due to inadequate financial support to farming and inadequate legit borrowing facilities in the study area. this implied that majority of respondents used fertilizer and pesticide for farming activities in the study. table-3. use of fertilizer and pesticide in parts of rivers niger and kaduna catchment, north central, nigeria. options upper zone middle zone lower zone yes 117 33.5% 85 24.3% 139 39.7% no 06 1.8% 01 0.3% 02 0.6% total 123 35.1% 86 24.6% 141 40.3% revelations from field interview shows that majority of the farmers across the zones have dropped the idea of traditional ways of crop improvements and presently adopted the use of synthetic fertilizers and pesticide. they gave the reasons that government subsidies, interventions and gifts from politicians have made it easier to acquire agrochemical. other reasons are scarcity in getting animal manure as the people in the area are not much involved in animal farming and faster results due to usage of synthetic fertilizers. the finding also revealed that pest infestations have been the reasons for pesticides use for farming in the study area. stakeholders’ interview shows intense use of agrochemical by all farmers in the study area. stakeholders’ views for agrochemical use also corroborated revelations by the farmers in the study area. similar indicators in this finding have been reported among smallholder farmers in developing countries [10]. 4.4. characteristics of the fertilizers and pesticides used in the study area table 4, describe the types of fertilizers been used across the zones in the study area for over 15 years. fertilizers identified been used in the study area include: nitrogen, phosphorus and potassium 17:17:17, nitrogen, phosphorus and potassium 23:23:0, diaminomethanal and calcium ammonium nitrate. the findings revealed majority of the farmers use nitrogen and phosphate based fertilizers for cropping and dressing in the area. these identified compounds of fertilizers have been designated to present potential health hazards [11]. table-4. list of fertilizers current use in parts of rivers niger and kaduna catchment, north central, nigeria. fertilizer trade name use nitrogen, phosphorus and potassium 17:17:17 npk 17:17:17 growing nitrogen, phosphorus and potassium 23:23:0 npk 23:23:0 growing nitrogen, phosphorus and potassium 20:20:0 npk 20:20:0 growing diaminomethanal (46%) urea dressing field interview from experienced district officers, extension agents and agrochemical vendors in the study area affirm the use of all agrochemical revealed to be in use by the farmers in the study area. further, pesticides identified in use currently in the study area include organophosphorus, synthetic auxins, thiadiazines, organochlorine, synthetic pyrethroids, triazoles flumiclorac pentyl-lactofen, triazine-amide, pyrazoles and organophosphorus-pyrethroids. as indicated in figure 2 percentage of pesticides compounds currently in use by farmers across the zones in the study area shows organophosphorus constitute 8.69%, synthetic auxins constitute 4.35%, thiadiazines constitute 4.35%, organochlorine pesticides constitute 34.78% indicating the highest compound of pesticides in use in the study area, synthetic pyrethroids constitute 8.69%, triazoles constitutes 4.35%, 4.35% are flumiclorac pentyl-lactofen, 13.04% are fungicides, 8.69% are triazine-amide, 4.35% pyrazoles and 4.35% are organophosphorus-pyrethroids. asian review of environmental and earth sciences, 2020, 7(1): 18-25 22 © 2020 by the authors; licensee asian online journal publishing group figure-2. percentage of pesticide compounds currently use in parts of rivers niger and kaduna catchment, north central, nigeria. figure-3. open market vendor of pesticides in parts of rivers niger and kaduna catchment, north central, nigeria. revelations by farmers, experienced district officers, extension agents and agrochemical vendors in the study area, all these pesticides are currently in used to control weed, pests and diseases. among them are pesticides banned in nigeria such as organochlorine insecticide ddt and its metabolites ddd and dde. a good number of synthetic chemical pesticides revealed being use in the study area are restricted for use and export in the european union eu. these include: abamectin, chlordane, dieldrin, endosulfan and aldrin. similar studies in developing countries reveals heavy use of pesticides in farming with much use of organochlorine pesticides as revealed in a number of previous studies [12];[13];[14]. 4.5. fertilizer application per hectare as indicated in table 5, fertilizer application per hectare ranges from 50kg to 170kg across the zones in the study area. 121 – 170kg fertilizer application ranked the highest in lower zones and 101 – 120kg ranked the least in middle zone. this implies that the respondents in the study area applied high rate of fertilizer during farming activities and it improved crop yield but in turn lead to water quality degradation. asian review of environmental and earth sciences, 2020, 7(1): 18-25 23 © 2020 by the authors; licensee asian online journal publishing group table-5. fertilizer application per hectare in parts of rivers niger and kaduna catchment, north central, nigeria. options upper zone middle zone lower zone 50 – 100kg 47 13.4% 21 6.0% 41 11.7% 101 – 120kg 45 12.9% 20 5.7% 31 8.8% 121 – 170kg 31 8.9% 45 12.9% 69 19.7% total 123 35.2% 86 24.6% 141 40.2% field interview also revealed that all the farmers applied fertilizers to their crops manually by direct application to crops or hand spray. fertilizers were mostly applied during land preparation and crops growing. the farmers mostly get their fertilizers from agrochemical vendors, government subsidies, intervention and gifts from politicians. farmers’ interview in the area revealed not having been trained on agrochemical use but usually receive some guides from the local vendors. most of the farmers in the study area revealed using fertilizers for the past fifteen (15) years. finding during interviews and field observations show that most of the farmers do not care about sustainable use of fertilizers in their farming as it was evident that more quantities of fertilizers were been used above recommended rate. the implication of this findings could have serious negative effect on environment, health risk and subsequent impacts on economic development in the study area. similar situation of excessive and unsuitable use of fertilizers have been reported in most developing countries including nigeria [15];[16]. 4.6 pesticide application per hectare as indicated in table 6, pesticide application per hectare ranges from 5 to 10litres in the study area. 10 litres and above of pesticide application ranked the highest in lower zones with 69 respondents and 5 – 7 litres ranked the least in middle zone with 19 respondents. this implies that the respondents in the study area applied high rate of pesticide during farming activities and it improved crop yield but in turn lead to water quality degradation. table-6. pesticide application per hectare in parts of rivers niger and kaduna catchment, north central, nigeria. options upper zone middle zone lower zone 5 – 7litres 41 11.7% 19 5.4% 41 11.7% 8 – 9litres 45 12.9% 20 5.7% 31 8.8% 10litres and above 37 10.6% 47 13.4% 69 19.7% total 123 35.2% 86 24.6% 141 40.2% the farmers in the area revealed getting the pesticides used in farming from local vendors, government intervention and gifts from politicians. these pesticides are applied by all the farmers across the zones using knapsack sprayer. there was no consideration of wind direction, timing considerations and proximity to vulnerable areas by farmers during application. the findings also discovered that the farmers do not abide by the inscribed instructions or directives on the agrochemical containers and uses their own discretion for measurement and mixing, by so doing, higher rate of pesticides is being applied on the farmlands beyond recommended rates. most of the farmers revealed using pesticides on their farming since past ten years but much in last four to five years. finding also shows that only 35% of the respondents are aware of banned and restricted pesticides in nigeria but could not tell the categories of those pesticides involved. the implication of these indicators will be counterproductive in achieving healthy socio-economic wellbeing of the inhabitants in the study area. indicators identified in this study are similar to findings in a number of studies in developing countries including nigeria [17];[18];[13]. 4.7 disposal mechanism of the used containers as revealed in figure 4, empty pesticides containers/bottles were dispose into the disposal pit, throw in the latrine, just discard them in the farm, destroy and burn or bury and keep for re-use. just discard them in the farm ranked the highest with 203 respondents, discard in the nearby bushes/roadsides ranked second with 70 respondents, disposing into the disposal pit ranked third with 50 respondents and dispose in latrine ranked the least with 27 respondents. this implies that majority of the respondents dispose their empty bottles of pesticides in their farms and this will lead to increase of plastic waste in their farms as well as environmental pollution. the findings from further appraisals revealed that most of the farmers in the area washed the application tools after spraying in the rivers, streams and pounds. virtually all the farmers have little or no measures towards water conservation and protection in the study area. these attitudes discovered could lead to water quality degradation, biodiversity disruption and subsequent negative impact on economic development in the study area. asian review of environmental and earth sciences, 2020, 7(1): 18-25 24 © 2020 by the authors; licensee asian online journal publishing group figure-4. shows disposal mechanism of empty pesticides containers/bottles in parts of rivers niger and kaduna catchment, north central, nigeria. similar situation has been reported previously in developing countries [19]. also leftover spray mixture was often emptied into streams or near a near water bodies in the study location. this finding is in line with discovery in a number of studies in nigeria [20];[21]. 5. conclusion and recommendations it was established that the farmers in the study area uses various compounds of synthetic pesticide and fertilizers in their farming activities. the types of pesticides compounds identified in used in the study area include: organochlorine and organophosphorus based which are known to present serious negative socio-economic effects. organochlorine based pesticides identified in used in the study area constitutes highest percentage at 34.78% while organophosphorus based pesticides constitutes 8.69%. nitrate, nitrite and phosphate based fertilizers were also identified in use in the study area. it was also established that farmers in the study area have not adopted environmental sustainable measures in pesticides and fertilizers use in farming activities. this conduct by farmers in the area can lead to contamination of water and biota. more so, potential negative effects on socio-economic wellbeing of communities in the study area can be expected. in view, of the aforementioned, it is recommended that visible and effective environmental management policies in respect of agrochemical use in the study area be put in place. also, government dedication, political wills, and collective responsibility of all stakeholders toward agrochemical management and ensuring sustainable farming practices involving the use of pesticides and fertilizers in the study area to guarantee cleaner and healthier environment for all. references [1] j. mohamed, s. murimi, and c. kihampa, "degradation of water resources by agricultural pesticides and nutrients, weruweru, tanzania," iranica journal of energy & environment, vol. 5, pp. 192-201, 2014.available at: https://doi.org/10.5829/idosi.ijee.2014.05.02.11. [2] t. joko, s. anggoro, h. r. sunoko, and s. rachmawati, pesticides usage in the soil quality degradation potential in wanasari subdistrict. brebes, indonesia: applied and environmental soil science, 2017. [3] h. j. keri and e. i. directorate, "nigeria’s status on pesticide registration and maximum residue levels," presented at the the workshop on pesticide maximum residue levels (mrls) held in alexandria, egypt, 2009. [4] a. ramteke and p. shirgave, "study the effect of common fertilizers on plant growth parameters of some vegetable plants," journal of plant product and natural resources, vol. 2, pp. 328-333, 2012. [5] t. c. ogwueleka, "assessment of the water quality and identification of pollution sources of k aduna r iver in n iger s tate (n igeria) using exploratory data analysis," water and environment journal, vol. 28, pp. 31-37, 2014.available at: https://doi.org/10.1111/wej.12004. [6] i. ahmed, "deforestation and consequences, a case study of mokwan local government are, postgraduate diploma research project, federal university of technology minna, 2001.," 2001. [7] i. banerjee, s. tripathi, a. s. roy, and p. sengupta, "pesticide use pattern among farmers in a rural district of west bengal, india," journal of natural science, biology, and medicine, vol. 5, pp. 313-316, 2014.available at: https://doi.org/10.4103/0976-9668.136173. [8] m. w. githinji, f. mwaura, and j. wamalwa, "land use and water pollution along the altitudinal gradient of the likii river, laikipia county, kenya," journal of environment pollution and human health, vol. 7, pp. 39-52, 2019. [9] p. a. ugbah, o. olaniyan, s. d. francis, and a. james, "impact of climate change on growing season in nigeria: seasonal rainfall prediction (srp) as assessment and adaptation tool," handbook of climate change resilience, pp. 1-27, 2019. [10] s. njoroge, a. g. schut, k. e. giller, and s. zingore, "learning from the soil’s memory: tailoring of fertilizer application based on past manure applications increases fertilizer use efficiency and crop productivity on kenyan smallholder farms," european journal of agronomy, vol. 105, pp. 52-61, 2019.available at: https://doi.org/10.1016/j.eja.2019.02.006. [11] e. solgi, h. sheikhzadeh, and m. solgi, "role of irrigation water, inorganic and organic fertilizers in soil and crop contamination by potentially hazardous elements in intensive farming systems: case study from moghan agro-industry, iran," journal of geochemical exploration, vol. 185, pp. 74-80, 2018.available at: https://doi.org/10.1016/j.gexplo.2017.11.008. [12] a. buah-kwofie, m. s. humphries, and l. pillay, "dietary exposure and risk assessment of organochlorine pesticide residues in rural communities living within catchment areas of isimangaliso world heritage site, south africa," environmental science and pollution research, vol. 26, pp. 17774-17786 2019.available at: https://doi.org/10.1007/s11356-019-05046-9. asian review of environmental and earth sciences, 2020, 7(1): 18-25 25 © 2020 by the authors; licensee asian online journal publishing group [13] y. a. adeshina, a. solomon, and a. f. ademola, "contamination levels of organochlorine and organophosphorous pesticide residues in water and sediment from river owena, nigeria," current journal of applied science and technology, vol. 34, pp. 1-11, 2019.available at: https://doi.org/10.9734/cjast/2019/v34i230119. [14] j. p. unyimadu, o. osibanjo, and j. o. babayemi, "concentration and distribution of organochlorine pesticides in sediments of the niger river, nigeria," journal of health and pollution, vol. 9, p. 190606, 2019.available at: https://doi.org/10.5696/2156-96149.22.190606. [15] a. m. igué, i. balogoun, a. saidou, a. c. oga, g. ezui, s. youl, and j. m. sogbedji, recommendations of fertilizer formulas for the production of the evdt 97 maize variety in northern benin. cham: in improving the profitability, sustainability and efficiency of nutrients through site specific fertilizer recommendations in west africa agro-ecosystems. springer, 2018. [16] y. hassan and n. hussain, "agricultural pollution: an assessment of synthetic fertilizer application in sudano-sahelian zone of nigeria," annals of social sciences management studies, vol. 2, p. 555579, 2018. [17] p. g. bertrand, "uses and misuses of agricultural pesticides in africa: neglected public health threats for workers and population, in pesticides-use and misuse and their impact in the environment. intech open," 2019. [18] h. machekano, w. masamba, b. m. mvumi, and c. nyamukondiwa, "cabbage or ‘pesticide’on the platter? chemical analysis reveals multiple and excessive residues in african vegetable markets," international journal of food contamination, vol. 6, pp. 1-13, 2019.available at: https://doi.org/10.1186/s40550-019-0072-y. [19] m. b. sosan and a. e. akingbohungbe, "occupational insecticide exposure and perception of safety measures among cacao farmers in southwestern nigeria," archives of environmental & occupational health, vol. 64, pp. 185-193, 2009.available at: https://doi.org/10.1080/19338240903241077. [20] a. adewoye, a. olayinka, and a. abimbola, "hydrogeochemical geometry of subsurface layers in odo-oba town, southwestern nigeria," journal of emerging trends in engineering and applied sciences, vol. 10, pp. 61-72, 2019. [21] a. j. anifowose and a. w. oyebode, "studies on heavy metals contents of osun river at the pre-urban settlement and across osogbo city, nigeria," journal of taibah university for science, vol. 13, pp. 318-323, 2019.available at: https://doi.org/10.1080/16583655.2019.1567899. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 47 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 47-54, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi:10.20448/journal.506.2020.71.47.54 © 2020 by the authors; licensee asian online journal publishing group analysis of spatial dependence of ore-forming elements using geostatistics and moran correlogram thanh tien nguyen ( corresponding author) faculty of surveying, mapping and geographic information, hanoi university of natural resources and environment, bac tu liem, hanoi, vietnam. abstract the spatial dependence of data obtained from the geochemical prospecting process can provide useful information for evaluating mineralization potential. this study proposes two approaches to study the spatial dependence of ore-forming elements. to reduce the influence of extreme values and outliers, a semi-variogram was first used to study spatial variability and degree of spatial dependence of geochemical data using cressie robust semi-variogram estimator. the moran spatial correlogram was then employed to describe spatial heterogeneity and to test for the presence of spatial autocorrelation in geochemical data. the moran‟s i statistics is strongly sensitive to positively skewed distribution, therefore, geochemical data were box-cox transformed before computing spatial correlograms. results from a case study of ag and au elements in jiurui copper districts (southeast china) have shown that moderate spatial dependence was found for both of the au and ag variables, the maximum spatial variability was 20 km for au and 10 km for ag, respectively. the degree of spatial dependence among geochemical data decreases as distances increase. these findings demonstrate that the spatial dependence of ore-forming elements can be effectively measured using geostatistics and moran correlogram. keywords: geostatistics, cressie semi-variogram, moran correlogram, geochemistry, spatial autocorrelation, spatial dependence, spatial variability, jiurui copper districts (china). citation | thanh tien nguyen (2020). analysis of spatial dependence of ore-forming elements using geostatistics and moran correlogram. asian review of environmental and earth sciences, 7(1): 47-54. history: received: 30 december 2019 revised: 4 february 2020 accepted: 6 march 2020 published: 10 april 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: the author thanks the editor and anonymous reviewers for their constructive comments, which have greatly improved this manuscript, and dr. peng gong (formerly of china university of geosciences) for providing geochemical data. competing interests: the author declares that there are no conflicts of interests regarding the publication of this paper. funding: this study was financially supported by the yangtze river delta 3d geological survey project (grant number 1212011220250). transparency: the author confirms that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 48 2. description of the study area and data used ........................................................................................................................... 48 3. methodology ..................................................................................................................................................................................... 48 4. results and discussions .................................................................................................................................................................. 51 5. conclusions ....................................................................................................................................................................................... 53 references .............................................................................................................................................................................................. 53 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.47.54&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1494 https://orcid.org/0000-0002-7600-5858 https://www.asianonlinejournals.com/index.php/arees/article/view/1494 https://orcid.org/0000-0002-7600-5858 https://www.asianonlinejournals.com/index.php/arees/article/view/1494 https://orcid.org/0000-0002-7600-5858 asian review of environmental and earth sciences, 2020, 7(1): 47-54 48 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study proposes approaches for assessing spatial dependence of geochemical elements based on geostatistics and moran correlogram. 1. introduction geochemists examine the spatial patterns of geochemical elements to understand the mechanisms and that control their spatial distribution. therefore, an understanding of the spatial distribution of geochemical elements has important implications. the spatial structures of geochemical elements can be studied using a semi-variogram and spatial correlogram. classical semi-variogram was used to study spatial variability and degree of spatial dependence of the data. however, the main limitation of this approach is that the sample mean is not a stable estimator of theoretical mean. one single outlier or an extreme value can destroy this estimator completely [1]. besides, the distribution of these elements is positively skewed, so the classical semi-variogram estimator is unbiased. for that reason, motivated by robust statistics, several types of semi-variogram estimators, based on robust estimation of scale and quantiles have been considered. a typical robust semi-variogram proposed by armstrong and delfiner [2] is the median of the magnitude of increments. variants proposed include the quantile semi-variogram [3] the “huberized” semivariogram, the jack-knifing [4] and the semi-variogram of order ½ [5]. however, the curves do not satisfy the statistical properties of a semi-variogram. thus, a theoretical curve has to be fitted to the experimental one. several different approaches have been proposed in the literature such as manual fitting [6, 7] automatic fitting including least squares using ordinary least squares [8] generalized least squares [9, 10] restricted maximum likelihood [11] maximum likelihood [10] bayesian framework [12] minq estimation [13] and robust methods [14]. the spatial correlogram has been commonly used to describe spatial structures, spatial heterogeneity in quantitative ways and testing for the presence of spatial correlation in data. in addition, for multivariate data, sokal [15] and oden and sokal [16] proposed to construct a spatial correlation function based on the mantel [17] test of matrix correlation. bjørnstad and falck [18] proposed a spline correlogram, which provides a continuous and model-free function for the spatial covariance. the spline correlogram may be seen as a modification of the nonparametric covariance function of hall and co-workers [19, 20]. in this study, from the above-discussion, spatial variability and degree of spatial dependence of geochemical data are assessed using cressie robust semi-variogram. the moran correlogram was then employed to describe spatial heterogeneity and to test for the presence of spatial autocorrelation in geochemical data. 2. description of the study area and data used 2.1. description of the study area the jiurui ore district mainly consists of cu-au-mo deposits which are located at the transitional point of the arcuate structure of the middle-lower yangtze river metallogenic belt (eastern china) [21, 22]. the developed drape fractures in the study area are surrounded by six axial parallel nee supports, which form a closely linear drape belt. three diggings come from this drape fracture. fractures are mainly followed by the nww and nee directions and then followed by nnw and ne-nne directions. the first two control the distribution of magmatic rocks and ore deposits in this area. the last two have a conjugate structure for the first two. submarine sedimentation-related pyrite copper deposits are controlled by a secondary basin of the yangtze ancient sea basin. intermediate acidic magmatic activities-related hydrothermal deposits are controlled by the nee direction fault structure of yanshanian, but at the same time controlled by the inherited fault in the nww direction. 2.2. data used a total of 1341 composite samples representing about 5364 km2 were collected in the jiurui ore district at a scale of 1:200.000 regional stream sediment survey. the sampling density was 1 composite sample per 4 km2. multi-elements sediment geochemical surveys of streams were carried out in the study area including ag, as, au, be, cd, cu, hg, li, mn, mo, nb, pb, sb, sn, th, v, w, y, zn, al2o3, cao, k2o, na2o, etc., in which ag and au are ore-forming elements [23]. in addition, three geochemical associations of elements also caused the anomalous area in the study areas [24]. there are two metallogenenic series in the study area with a total of 13 known ore deposits. 3. methodology 3.1. cressie semi-variogram let consider a spatial stochastic process * ( ) +, where is a fixed subset of . assume that this stochastic process is ergodic and also satisfies the hypothesis of intrinsic stationarity, the expected (e) and variance (var) values of ( ) are given by hoang, et al. [25] in equations 1 and 2: ( ( )) (1) , ( ) ( ) ( ) (2) where: ( ) is the value of observed variable and ( ) is the semi-variogram of ( ) at lag . this is a very simple model that can be used in practice after detrending data [26] or in several cases even used directly. in this study, the semi-variogram of order ½ estimator will be used to estimate the robust semi-variogram. let * ( ) ( ) ( )+ be a sample of such a spatial stochastic process. the cressie robust semi-variogram estimator is expressed as the following equation: ̂( ) [ ∑ | ( ) ( )| ( ) ( ) ] ( )⁄ (3) asian review of environmental and earth sciences, 2020, 7(1): 47-54 49 © 2020 by the authors; licensee asian online journal publishing group where: ( ) {( ) } ( ) and ( ) are values of an observed variable at locations i and j, means that distances may be grouped into distance classes, placing in class the individual distances that are approximately equal to . the denominator of equation 3 corrects for bias under gausianity, and: ̂( ) [ {| ( ) ( )| ( ) ( )}] ( ) (4) where: ( ) and ( ) are defined as in equation 3, * + denotes the median of the sequence {| ( ) ( )| } and ( ) corrects for bias [assymptotically, ( ) ]. the reasoning behind equation 3 is that, for gaussian data, [ ( ) ( )] is a chi-squared random variable on one degree of freedom. the power transformation that makes this most gaussian-like is the fourth root [27] namely | ( ) ( )| , the square root of the absolute difference. thus, various location estimators can be applied to {[ ( ) ( )] ( ) ( )}, which, when untransformed and normalized for bias, yield robust semi-variogram estimators. a model must be fitted to the sample semi-variogram. the model will provide values of semi-variance for all the intermediate distances. the most commonly used models are the spherical model, exponential model, gaussian model, hole effect model, linear model, pure nugget effect model, etc as shown in figure 1. figure-1. commonly used variogram models. source: armstrong and delfiner [2]. semi-variograms may be used to determine whether anisotropy is present in the data set. they may also be used to describe anisotropic surfaces or to account for anisotropy in kriging interpolation [24]. a direction of space is first chosen (i.e. an angle ) and a search is then launched for the pairs of sampling points that are within a given distance class in that given direction. there may be only a few such pairs perfectly aligned in the aiming direction , or even none at all, in particular when sampling is not regularly spaced on the map. more pairs of points can usually be found by looking within a small neighborhood around the aiming line as shown in figure 2. the neighborhood is determined by an angular tolerance parameter and a parameter that sets the tolerance for distance classes along the aiming line. for each observed point in turn, one looks for other points that are at distance ± from it. all points found within the search-window are paired with the reference point included in the calculation of semi-variance for distance class [24]. in figure 2, from an observed study site , an aiming line is drawn in the direction determined by angle , the angular tolerance parameter determines the search zone (grey) laterally whereas parameter sets the tolerance along the aiming line for each distance class . figure-2. search parameters for pairs of points in the semi-variogram. source: legendre and legendre [24]. hoang, et al. [25] indicated that the distance at which the variance levels off is referred to as the range (or maximum spatial variability), a; beyond that distance, the sampling units are not spatially correlated. the parameter for the nugget effect is and the spatially structured component is represented by ; the sill, , is equal to figure 3. spatial variability can be investigated using the semi-variogram and the relative nugget effect, which is the ratio of the nugget to total semivariance expressed as percentage, ( ) [24]. a ratio of asian review of environmental and earth sciences, 2020, 7(1): 47-54 50 © 2020 by the authors; licensee asian online journal publishing group less than 25% indicates strong spatial dependence, between 25% and 75% indicates moderate spatial dependence, and greater than 75% indicates weak spatial dependence [1]. figure-3. characteristic features a spherical semivariogram model. source: legendre and legendre [24], hoang, et al. [25]. 3.2. moran correlogram spatial correlation of a uni-variate can be measured using spatial correlation statistics such as moran‟s i or geary‟s c statistics [27]. the moran's i statistics seems to be the most popularly used [1], that is given: ( ) ∑ ∑ ( ̅)( ̅) ∑ ( ̅) (5) where: and are the values of an observed variable at sites i and j, d is the distance class considered in the calculation, is the sum of the weights , given ∑ ∑ ̅ is the sample mean of an observed variable, given by: ̅ ∑ n stands for the number of observations with is spatial weight matrix for a given distance and is the distance between the observations i and j. spatial correlation coefficients can be tested for significance. the tests require that the condition of secondorder stationarity (or a relaxed form of stationarity, intrinsic stationarity). cliff and ord [27] describe how to compute confidence intervals and test the significance of spatial correlation coefficients. for any normally distributed statistic stat, a confidence interval at significance level α is obtained as follows: ( ⁄ √ ( ) ⁄ √ ( )) (6) in equation 6, for significance testing with large samples, a one-tailed critical value at significance level α is obtained as follows: √ ( ) (7) where: value ⁄ or in equation 6 and 7 is found in the table of standard normal deviates. it is possible to use this approach because moran‟s i is asymptotically normally distributed for data sets of moderate to large sizes [27]. under the hypothesis ( ) of the random spatial distribution of the observed values , the expected values (e) of moran‟s i statistic is given by the following equation: ( ) (8) where: is defined as in equation 5. it can be seen that, under the null hypothesis, ( ) approaches 0 as n increases. the variance is computed using equation 9 under a randomization assumption, which simply states that, under , the observations are independent of their positions in space (second-order stationarity assumption) and, thus, are exchangeable [27]. ( ) ( ) , ( ) ,( ) ,( ) ( )( )( ) ( ) (9) in equation 9, , , and can be obtained by the following equations: ∑∑( ) (10) ∑(∑( ∑ ) (11) ∑( ̅) [∑( ̅) ] (12) where: , , and are defined as in equation 5, and is number of observations. in most cases, tests of spatial correlation are one-tailed. geological variables are usually positively correlated at short distances. to carry out an approximate test of significance, a value of α is selected (e.g α = 0.05) and find in a table of the standard normal distribution (e.g ). critical values are found as equation 7 with a asian review of environmental and earth sciences, 2020, 7(1): 47-54 51 © 2020 by the authors; licensee asian online journal publishing group correction factor that becomes important when n is small: √ ( ) ( ) in all cases, using the value in the upper tail of the distribution when testing for positive spatial correlation (e.g , and the value in the lower tail in the opposite case (e.g ). the value taken by the correction factor depends on the values of n and . if ( √ ) ( √ ) √ ; otherwise, . if the test is two-tailed, use ⁄ to find and before computing critical values. the corrections are based upon simulations reported by cliff and ord [27]. other formulas can be found in cliff and ord [27] for conducting a test under the assumption of normality, where one assumes that the result of from independent draws from a normal population. it has been suggested that when n is very small, tests of i should be conducted by permutation [1, 24]. 4. results and discussions 4.1. spatial variability analysis data from figure 4-a and 4-b demonstrates that the semivariances for the variable au for the omni-directional semi-variogram and directional semi-variograms in four different directions. the experimental semi-variogram shows a big nugget effect, , which accounts for about 57% of the total sill after fitted with a theoretical model as shown in table 1. a ratio of nugget to total semivariance of 57% between 25% and 75% indicates moderate spatial dependence. the nugget effect shows a small-scale variation in the data due to the problem of sampling unintensiveness figure 4-a. however, there was a slightly significant difference in the variation according to four different directions. the directional semi-variograms displays the same sill. all curves start at about the same point. all curves of directional variograms of au almost flatten out at 20km and show small different total variances figure 4-b. similarly, the hole effect appears due to the presence of one or more mineral occurrences. table-1. summary table of geostatistical parameters of au and ag ore-forming elements. elements direction nugget effect ( ) spatially structure ( ) sill ( ) spatial range (km) (a) relative nugget effect ( ) au omni 0.21 0.16 0.37 35.9 57% ag omni 0.00025 0.00027 0.00052 15.5 48% figure-4. semi-variogram for the variables au and ag. data from figures 4-c and 4-d illustrates the semivariances for the variable ag for the omni-directional semivariogram additional to four directional variograms in different directions. experimental omni-directional variogram shows a moderate nugget effect, , which accounts for about 48% of the total sill after fitted with a theoretical model table 1. a ratio of nugget to total semivariance of 48% between 25% and 75% indicates moderate spatial dependence. the nugget effect of the variable ag also shows a small-scale variation in the data due to the problem of sampling unintensiveness. all curves start at about the same point and they flatten out at about 14km. the sampling units are not spatially correlated with no spatial dependence in the variable ag when the distance beyond 15.5km figures 4-c. directional semi-variograms vary strongly with directions and big different total variance when the distance is more than 14km, especially on the northeast-southwest, northwestsoutheast and north-south directions figure 4-d. it can be inferred that the hole effect appears due to the presence of one or more mineral occurrences. it reflects a tendency for high values to be systematically surrounded by low values and vice versa. asian review of environmental and earth sciences, 2020, 7(1): 47-54 52 © 2020 by the authors; licensee asian online journal publishing group 4.2. spatial structure analysis the surfaces in figures 5-a and 5-c were made from 1341 sampling points across the surface using a regular 49×38 grid (2×2 km in a grid). the “height” was noted at each sampling point. the distances among points were divided into 60 distance classes. testing the significance of correlograms with each distance class by randomization test with 500 times of permutation at the = 0.05 level. spatial correlograms were computed using the „raw‟ data. however, the distribution of the “raw” data is strongly right-skewed due to many extreme values and outliers. besides, moran‟s i statistics is very sensitive to extreme values and asymmetry in the data distributions. to easily reach significance in statistical tests, the data were box-cox transformed to compute moran‟s i correlograms. moran‟s i coefficients at distances ranging from 2 km to 34.8 km and their p-values of the au and ag variables are summarised in table 2. table-2. summary table of moran‟s i coefficients and p-values of au and ag elements using raw data and box-cox transformed data. distance (km) au ag raw data box-cox transformed data raw data box-cox transformed data moran’s i coefficient p-value moran’s i coefficients p-value moran’s i coefficient p-value moran’s i coefficient p-value 2.0 0.029 0.018 0.41 0.002 0.11 0.008 0.54 0.002 3.4 0.021 0.032 0.35 0.002 0.06 0.008 0.40 0.002 5.1 0.026 0.016 0.30 0.002 0.04 0.006 0.30 0.002 7.0 0.011 0.05 0.24 0.002 0.01 0.038 0.22 0.002 9.1 0.007 0.05 0.20 0.002 0.00 0.144 0.16 0.002 11.1 0.005 0.126 0.17 0.002 0.00 0.118 0.13 0.002 12.9 0.009 0.022 0.15 0.002 0.00 0.367 0.11 0.002 14.8 0.005 0.068 0.13 0.002 0.00 0.140 0.10 0.002 16.9 0.005 0.09 0.12 0.002 0.00 0.204 0.09 0.002 19.0 0.003 0.116 0.10 0.002 0.01 0.040 0.07 0.002 21.0 0.005 0.066 0.09 0.002 0.00 0.104 0.06 0.002 22.8 0.005 0.076 0.07 0.002 0.01 0.036 0.05 0.002 24.9 0.016 0.004 0.06 0.002 0.00 0.463 0.03 0.002 26.9 0.003 0.144 0.04 0.002 0.00 0.154 0.03 0.002 29.0 -0.003 0.246 0.00 0.218 0.00 0.126 0.04 0.002 30.9 0.007 0.038 0.00 0.210 -0.01 0.036 0.04 0.002 32.9 0.000 0.253 -0.01 0.092 0.00 0.122 0.03 0.002 34.8 0.001 0.257 -0.01 0.162 -0.01 0.034 0.02 0.002 data from moran‟s i correlogram of the au variable in figure 5-b and table 2 demonstrate that the first spatial correlation coefficient of 0.029 indicates a weak positive spatial correlation in the first distance class for the „raw‟ data. the second positive and significant spatial correlation coefficient of 0.021 occurs at distances ranging from 2 km to 3.4 km. the next positive spatial correlation coefficient was detected at distances from 11.1 km to 12.9 km. the last positive and significant correlation was found with a coefficient of 0.016. there was no spatial correlation (spatial dependence) at distances ranging from 2.0 km to 3.4 km, from 7.0 to 11.1 km, and from 12.9 km to 22.8 km, respectively. besides, negative and significant spatial correlation was detected at distances ranging from 50 km to 70 km. figure-5. the surface of au: raw data (a) and of transformed data (c) and moran correlogram: raw data (b) and transformed data (c). the surface and moran correlogram for box-cox transformed data of the variable au shown in figures 5-c and 5-d. data from table 2 demonstrates that the first spatial correlation coefficient of 0.41 was bigger than that of „raw‟ data. this trend is similar to the next spatial correlation coefficients with values of 0.35, 0.30, 0.24, and 0.20 at distances ranging from 3.4 km to 9.1 km. spatial correlation coefficients are gradually reduced as distances increase. positive and significant correlation coefficients were also found at distances below 26.9 km, whereas no asian review of environmental and earth sciences, 2020, 7(1): 47-54 53 © 2020 by the authors; licensee asian online journal publishing group spatial correlation was detected at distances ranging from 29 km to 34.8 km. negative and significant spatial correlation at distances from 32.9 km to 76 km. data from moran correlogram for the ag element in figure 6-b shows that three positive and significant spatial correlation coefficients were found at distances ranging from 2 km to 5.1 km, whereas, no spatial correlation was found at distances ranging from 5.1 km to 34.8 km. in addition, there existed negative and significant spatial correlation coefficients at distances ranging from 34.8 km to 44 km and no spatial correlation at distances above 44 km. the surface and moran‟s correlogram for box-cox transformed data of the variable ag in figures 6-c and 6-d show similarities with those obtained from the au variable, the first spatial correlation coefficient of 0.54 was much bigger than that of „raw‟ data and similarly for the next spatial correlation coefficients, 0.40, 0.30, 0.22, 0.16 at distances ranging from 3.4 km to 9.1 km. spatial correlation coefficients were also gradually reduced as distances increase. spatial correlogram in figure 6-d show that there existed positive and significant correlation at distances below 36.9 km and strong spatial correlation at distances below 12.9 km, weak spatial correlation at distances between 12.9 km and 36.9 km; no spatial correlation at distances from 30.9 km to 36.9 km, and negative and significant at distances from 36.9 km to 74 km. figure-6. the surface of ag: raw data (a) and of transformed data (c) and moran correlogram: raw data (b) and transformed data (c). 5. conclusions in this study, cressie robust semi-variogram and moran correlogram have been employed to study the spatial dependence of ore-forming elements. cressie robust semi-variogram was first used to study spatial variability and identify the level of spatial dependence in data. the moran spatial correlogram was then applied to describe spatial structure and spatial heterogeneity. results from a case study of ag and au elements in jiurui copper districts have shown that moderate spatial dependence was found for both of the au and ag variables, the maximum spatial variability was 20 km for au and 10 km for ag, respectively. an important conclusion can be made is that the results were strongly affected by the existence of extreme values and outliers, so it is suggested that the raw data should be transformed. in addition, the precision of the spatial correlogram depends on spatial classes (distances), whereas, the computational complexity is remarkably increased when spatial classes are decreased. references [1] l. anselin, "local indicators of spatial association—lisa," geographical analysis, vol. 27, pp. 93-115, 1995. available at: https://doi.org/10.1111/j.1538-4632.1995.tb00338.x. [2] m. armstrong and p. delfiner, towards a more robust variogram: a case study on coal. paris: springer, 1980. [3] o. n. bjornstad and w. falck, "nonparametric spatial covariance functions: estimation and testing," environmental and ecological statistics, vol. 8, pp. 53-70, 2001. [4] c. chung, "use of the jackknife method to estimate autocorrelation functions (or variograms), in geostatistics for natural resources characterization," ed dordrecht: springer, 1984, pp. 55-69. [5] n. cressie and d. m. hawkins, "robust estimation of the variogram: i," journal of the international association for mathematical geology, vol. 12, pp. 115-125, 1980. [6] m. hohn, "geostatistics and petroleum geology," ed the netherlands: springer science & business media, 1998, pp. 100-138. [7] r. a. olea, "geostatistics for engineers and earth scientists," ed the netherlands: springer science & business media, 2012, pp. 10-40. [8] m. david, "geostatistical ore reserve estimation," ed the netherlands: elsevier, 2012, pp. 73-90. [9] n. cressie, "fitting variogram models by weighted least squares," journal of the international association for mathematical geology, vol. 17, pp. 563-586, 1985. available at: https://doi.org/10.1007/bf01032109. [10] n. cressie, "statistics for spatial data," ed new york: john wiley & sons, 2015, pp. 27-104. [11] m. g. kenward and j. h. roger, "small sample inference for fixed effects from restricted maximum likelihood," biometrics, vol. 53, pp. 983-997, 1997. available at: https://doi.org/10.2307/2533558. [12] t. egeland, p. mostad, n. hjort, a. kraggerud, and p. biver, "variogram estimation in a bayesian framework," geostatistics wollongong, vol. 96, pp. 223-233, 1997. [13] c. r. rao and j. kleffe, "estimation of variance components,statistics and probability." vol. 3, ed amsterdam: north-holland, 1988, p. 370. [14] w. h. fellner, "robust estimation of variance components," technometrics, vol. 28, pp. 51-60, 1986. [15] r. r. sokal, "spatial data analysis and historical processes," data analysis and informatics vol. 4, pp. 29-43, 1986. asian review of environmental and earth sciences, 2020, 7(1): 47-54 54 © 2020 by the authors; licensee asian online journal publishing group [16] n. l. oden and r. r. sokal, "directional autocorrelation: an extension of spatial correlograms to two dimensions," systematic zoology, vol. 35, pp. 608-617, 1986. available at: https://doi.org/10.2307/2413120. [17] n. mantel, "the detection of disease clustering and a generalized regression approach," cancer research, vol. 27, pp. 209-220, 1967. [18] o. n. bjørnstad and w. falck, "nonparametric spatial covariance functions: estimation and testing," environmental and ecological statistics, vol. 8, pp. 53-70, 2001. [19] p. hall, n. i. fisher, and b. hoffmann, "on the nonparametric estimation of covariance functions," the annals of statistics, vol. 22, pp. 2115-2134, 1994. available at: https://doi.org/10.1214/aos/1176325774. [20] p. hall and p. patil, "properties of nonparametric estimators of autocovariance for stationary random fields," probability theory and related fields, vol. 99, pp. 399-424, 1994. available at: https://doi.org/10.1007/bf01199899. [21] t. t. nguyen, d. t. vu, l. h. trinh, and t. l. h. nguyen, "spatial cluster and outlier identification of geochemical association of eements: a case study in juirui copper mining area," bulletin of the mineral research and exploration, vol. 53, pp. 159-167, 2016. available at: https://doi.org/10.19111/bmre.01695. [22] t. t. nguyen and t. d. vu, "identification of multivariate geochemical anomalies using spatial autocorrelation analysis and robust statistics," ore geology reviews, vol. 111, pp. 1-16, 2019. [23] t. t. nguyen, "use of moran's i and robust statistics to separate geochemical anomalies in jiurui area (southeast china)," bulletin of the mineral research and exploration, vol. 156, pp. 22-44, 2018. [24] p. legendre and l. f. legendre, numerical ecology. the netherlands: elsevier, 2012. [25] h. a. hoang, t. d. vu, and t. t. nguyen, "spatial variability analysis of cu content: a case study in jiurui copper mining area," international journal of applied geospatial research (ijagr), vol. 8, pp. 81-93, 2017. available at: https://doi.org/10.4018/ijagr.2017010105. [26] e. r. ziegel, "geostatistical software library and user's guide," technometrics, vol. 40, p. 357, 1998. [27] a. d. cliff and j. k. ord, spatial processes: models and applications. pion, london: taylor & francis, 1981. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 1 asian review of environmental and earth sciences vol. 5, no. 1, 1-7, 2018 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.1.7 adsorptive removal of a pharmaceutical and personal care product oxybenzone from water with metal-organic frameworks naz fathma tumpa1✍ yeon-koo jeong2 (+ corresponding author) 1,2department of environmental engineering, waste management and resource recycling research lab, kumoh national institute of technology, gumi, republic of korea abstract oxybenzone, one of the most often detected pharmaceuticals and personal care products (ppcps), from aqueous solutions and this ppcps removal from water had been studied by using the highly porous metal-organic framework (mof) ) mil-101(cr) and a modified mil-101(cr) called mil101-oh. adsorption results showed that mil-101-oh which contains functional group such as – oh, which was very effective for oxybenzone adsorption. the adsorption performance of mil101-oh over mil-101-oh was found to be greater than that of mil-101(cr), which means the functionalization of primitive mofs have a positive effect on adsorption. the kinetics of mil101-oh also showed higher result compare to mil-101(cr). so along with a high adsorption capacity and repaid adsorption which is important for commercial applications. keywords: personal care product, metal-organic frameworks, oxybenzone, adsorption, porous materials, aqueous solution citation | naz fathma tumpa; yeon-koo jeong (2018). adsorptive removal of a pharmaceutical and personal care product oxybenzone from water with metal-organic frameworks. asian review of environmental and earth sciences, 5(1): 1-7. history: received: 3 november 2017 revised: 20 december 2017 accepted: 3 january 2018 published: 8 january 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: both authors contributed to the conception and design of the study. funding: this research was supported by kumoh national institute of technology (kit), gumi, republic of korea. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ........................................................................................................................................................................ 2 2. experimental ...................................................................................................................................................................... 2 3. results and discussion .................................................................................................................................................... 3 4. conclusion ........................................................................................................................................................................... 5 references ................................................................................................................................................................................ 5 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.1.7&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/0000-0003-0992-4122 https://orcid.org/0000-0002-1612-8194 https://orcid.org/0000-0003-0992-4122 https://orcid.org/0000-0002-1612-8194 https://orcid.org/0000-0003-0992-4122 https://orcid.org/0000-0002-1612-8194 https://orcid.org/0000-0003-0992-4122 https://orcid.org/0000-0002-1612-8194 asian review of environmental and earth sciences, 2018, 5(1): 1-7 2 1. introduction the use of pharmaceuticals and personal care products (ppcps) is increasing day by day because of the increasing population all over the world, urbanization and living standards. for example the presence of ppcps is already detectable in surface water, as in ground water [1-3] and bioaccumulation of these persistent ppcps in the aquatic life will become a threat to the environment [4, 5]. ppcps may often remain in the environment even after they have been consumed completely [3, 6-10] because ppcps usually have long shelf lives to meet customer’s demands, and some ppcps are inadvertently dumped into environment; therefore, ppcps are typical examples of so-called emerging contaminants [9, 10]. oxybenzone (the structure of which is shown in scheme 1) is a component of many sunscreen lotions, is regarded as typical emerging contaminants with high environmental risk. the chemical structure of oxybenzone has various functional groups such as phenol, ketone groups that can interact effectively with adsorbents such as modified / functionalized mofs. (2-hydroxy-4-methoxyphenyl)-phenylmthanone [c14h12o2] scheme-1. chemical structure of oxybenzone over last few decades, significant advancements have been achieved in the field of porous materials because of the development of new functional materials, including metal-organic frameworks (mofs) [11-19]. mofs are receiving much attentions because of their high porosity, with their pore size/shape being controllable over both microporous and mesoporous regions. the physiochemical properties of mof materials can be turned with easy modifications or functionalization, which ultimately increases their usability in various applications, such as adsorption [20-22] separation [23] and catalysis [24] for example mofs have recently been successfully used for fuel purification via adsorptive desulfurization [25-27] or denitrogenation [28-30]. mofs have also been used for the aqueous-phase adsorption of different pollutants in water, such as heavy metals [31] phosphate [32] organics dyes [33-36] organic arsenic acids [37, 38] bisphenol-a [39, 40] and ppcps (naproxen and clofibric acid) ) [41-43] from water. in this study, we used mil-101, mil-101-oh and oxybenzone as representatives mof and ppcp, respectively. 2. experimental 2.1 chemicals and synthesis and modification of adsorbent reagents and solvents were commercially available products and used without any further purification. chromium (iii) nitrate nanohydrate (cr(no3)3.9h2o) (99%) and terephthalic acid (tpa,99%) were purchased from daejung and junsei chemicals, repectively. ethanolamine (eta,98%) was obtained from alfa aesar. toluene (99.5%) was procured from daejung chemicals. n,n-dimethylformamide (99%) and ethanol (99.5%) for the purification of the mofs were obtained from daejung chemicals. methanol and acetone were obtained from daejung chemicals, and oxybenzone was obtained from alfa aesar. mil-101 was synthesized from cr(no3)3.9h2o, tpa, and deionized water similar to a previously described method [44-46]. cr(no3)3.9h2o (4.0 g) 10 mmol, terephthalic acid (tpa) (1.66 g) 10 mmol, and deionized water (40ml) were blended and briefly sonicated resulting in a dark blue-color suspension. the suspension was then placed in a teflon-lined autoclave bomb and was kept in an oven at 220°c for 17 h without stirring. after the reaction, autoclave was cool to room temperature. after that the mof solids with green-colored was separated from water using a centrifuge (3,134xg, 15min) and was washed with water, methanol and acetone. the suspension in acetone was centrifuged and separated, to remove the unreacted tpa, the solids was placed in n,ndimethylformamide (40 ml) and the suspension was sonicated for 10 min and then keep at 70 °c overnight. the resulting solids were separated by centrifugation, repeatedly washed with methanol and acetone, was dried at 100°c overnight. the –oh functionalized mil-101s name mil-101-oh was synthesized via grafting utilizing reported procedures [43, 47]. before functionalization, mil-101 was dehydrated at 150 0c for 12 h in a vacuum oven to generate cuss (coordinatively unsaturated sites ).the dehydrated mil-101 (0.6 g) was suspended in anhydrous toluene (60 ml) in a round-bottom flask equippe with a reflux condenser and a magnetic stirrer, and each of 2 mmol of eta (ethanolamine) was added to this suspension. the mixture continuously was stirred and refluxed for 12 h. the obtaind solid was cool to room temperature, was separated and was washed with ethanol/de-ionized water, and was dried at room temperature and then the mofs solid was kept in desiccators for further use. 2.2 characterization x-ray powder diffraction patterns were obtained with a diffractometer (swxd, cukα radiation). ft–ir spectra were recorded on a hyperion-2000 (atr, maximum resolution). the nitrogen adsorptions of the adsorbents was obtain at -196 0c with a surface area and porosity analyzer (brlsorp-max) after evacuation at 150 0c for 12 h. the surface area of adsorbents was calculated using the bet equation. asian review of environmental and earth sciences, 2018, 5(1): 1-7 3 2.3 general procedures for the adsorption experiments oxybenzone solutions with the desired concentrations were prepared using deionized water. an oxybenzone calibration curve was prepared by determining the absorbance at 230 nm with a series of standard oxybenzone solutions (1–10 mg/l), and the initial or equilibrium concentrations of oxybenzone was calculated with the calibration curve. formerly to adsorption, the sample was dried for 12 h at 100 0c under vacuum conditions. for each adsorption experiment, approximately 5 mg of the sample was added to the oxybenzone solution (50ml, fixed concentration) and was stirred for 10 min to 12 h at 25 0c. after stirring the solution, the adsorbents was filtered with a syringe filter (ptfe, 0.45 µm) and the oxybenzone concentration was determined from the absorbance of the uv spectrum. in the case of a high oxybenzone concentration, the uv analysis was conducted after consecutive dilutions of the oxybenzone solutions. the following mass-balance relation (eq.1) was used to determine the amount of adsorbed oxybenzone ⁄ (1) where c0 (mg/l) was the initial concentration, ct (mg/l) was the concentration at time t, v(l) was the volume of the oxybenzone solution and w(g) was the weight of the adsorbents. 3. results and discussion 3.1 characterization of the adsorbents the xrd patterns of the mil-101s shown in fig. 1a was accommodating with simulated one [43, 44] confirmed the mil-101s were successfully prepared and that the crystal structure of pristine mil-101 does not change with functionalization. however, the xrd intensities of the mil-101s decreased slightly on modification, particularly those of mil-101-(oh), probably because of some severe conditions which was required for these modifications. the nitrogen adsorption isotherms of the mil-101s and the bet surface areas (table 1) obtained from these isotherms show that the mil-101s have considerable porosities, although functionalization (to introduce –oh group) reduced the porosities. this reduction could be due to the volumes of the functional groups and/or the decreased crystallinity with modifications (as shown by the xrd patterns). ftir spectra of the modified mofs shown in fig. 2c confirmed the grafting was successful based on the presence of the band at 1216 cm−1, which originate from the c-n stretching of the grafting agents [48]. (b) (blue color – mil-101(cr) & red colormil-101-oh) figure-1. (a) xrd patterns, and (b) ftir spectra of mil-101s table-1. bet surface areas and total pore volume of mil-101s adsorbent bet surface area sabet(m2/g) total pore volume [cm3 g-1] mil-101(cr) 2,534.4 1.847 mil-101-oh 1,951.5 0.9615 3.2 adsorption isotherms and kinetics results isotherms for oxybenzone adsorption by mil-101s were obtained at 20-25 °c after 12 h of adsorption, which is sufficient for equilibrium, and the results are shown in fig. 3. the adsorbed amounts (based on weight of mil101s) at equilibrium decreased in the order mil-101–oh > mil-101, which was the same order as observed for quantity adsorbed after various times with different concentration (fig.2). the maximum adsorbed quantities (q0) obtained from langmuir plots are summarized in table 2, and the results again show that mil-101s functionalized with –oh groups were highly effective at adsorbing oxybenzone from water. table-2. relative adsorbed amounts of ppcps over the two mofs (mil-101, mil-101-oh) after 12 h of adsorption mofs ppcps maximum adsorption (q0 mg/g) r² mil-101(cr) oxybenzone 73.50 0.9999 mil-101-oh oxybenzone 121 0.9998 isotherms for ibuprofen adsorption by mil-101s were obtained at 25 °c after 12 h of adsorption, which is sufficient for equilibrium, and the results are shown in fig. 3. the adsorbed amounts (based on weight of mil asian review of environmental and earth sciences, 2018, 5(1): 1-7 4 101s) at equilibrium decreased in the order mil-101–oh > mil-101, which was the same order as observed for quantity adsorbed after various times (fig.2). the maximum adsorbed quantities (q0) obtained from langmuir plots are summarized in table 1, and the results again show that mil-101s functionalized with –oh groups were highly effective at adsorbing ibuprofen from water. (a) mil-101(cr) (b) mil-101(cr) figure-2. effect of adsorption times on the adsorbed amounts of oxybenzone over (a) mil-101(cr) and (b) mil-101-oh. show the adsorbed amounts of oxybenzone based on the unit weight of adsorbents. the initial concentration of oxybenzone was (10-50 ppm.) the kinetics of oxybenzone adsorption of different concentration over mil-101(cr) and mil-101-oh had been calculated. oxybenzone adsorption kinetics followed previously described method [49] the pseudo-secondorder equation can exactly illustrated. the equation (2) for pseudo-second-order model which can explain the kinetics has given below -(2) qt(mg/g) at time t, the amount of adsorbed, qe (mg/g) at equilibrium stage the amount of adsorbed, t(hour) time (adsorption time) and k2(g/mg, hour) pseudo-second-order rate constant. the kinetics results of oxybenzone adsorption over mil-101s have been given in table 3. the kinetics of oxybenzon adsorption over mil-101s showed that the qe value and k2 value of oxybenzone adsorption over mil-101(cr) and mil-101-oh were decreased in the order of mil-101-oh > mil-101(cr) respectively. the kinetics of oxybenzon adsorption over mil-101s showed that the qe value and k2 value of oxybenzone adsorption over mil-101(cr) and mil-101-oh were decreased in the order of mil-101-oh > mil-101(cr) respectively. 0 20 40 60 80 100 120 0 2 4 6 8 10 12 14 a m o u n t ad so rb ed ( m g/ g) time (h) 50 ppm 40 ppm 30 ppm 20 ppm 10 ppm 0 20 40 60 80 100 120 0 2 4 6 8 10 12 14 a m o u n t ad so rb ed ( m g/ g) time (h) 50 ppm 40 ppm 30 ppm 20 ppm 10 ppm asian review of environmental and earth sciences, 2018, 5(1): 1-7 5 table-3. the kinetics of oxybenzone adsorption over mil-101(cr) and mil-101-oh. [when the concentrations of oxybenzone solutions were 40 & 50ppm] mof(adsorbent) initial concentration qe (mg/g) k2(g/mg,hour) mil-101(cr) 10ppm 47.26 0.0291 20ppm 63.59 0.0305 30ppm 67.90 0.0312 40ppm 69.92 0.0372 50ppm 70.94 0.0475 mil-101-oh 10ppm 60.25 0.0385 20ppm 81.05 0.0403 30ppm 92.34 0.0422 40ppm 102.12 0.0528 50ppm 104.16 0.0561 figure-3. adsorption isotherms of oxybenzone over (a) mil-101 and (b) mil-101-oh (at 2025 °c) 3.3 discussion from the above tables (table 2 and table 3), q0 means the highest oxybenzone adsorption capacity of mofs and qe means the adsorbed amount during equilibrium. so in this research the highest oxybenzone adsorption capacity of mil-101(cr) was 73.50 mg/g (based on unit weight of mil-101) and highest oxybenzone adsorption capacity of mil-101-oh was 120 mg/g (based on unit weight of mil-101-oh) and the kinetics of oxybenzon adsorption over mil-101s showed that the qe value and k2 value of oxybenzone adsorption over mil-101(cr) and mil-101-oh were decreased in the order of mil-101-oh > mil-101(cr)respectively. so on the basis of comparison the adsorption capacity of mil-101-oh was higher than the adsorption capacity of mil-101(cr), and oxybenzone’s adsorption capacity of both mofs were decreased on the order mil-101-oh > mil-101(cr) (based on unit weight). the reason for which, mil-101-oh oxybenzone’s adsorption capacity was higher compared to mil-101(cr) because it contain h-bonding and that h-bonding was maybe responsible for making mil-101-oh more capable for oxybenzone’s higher adsorption. again from the kinetics the qe value and k2 value of oxybenzone adsorption over mil-101(cr) and mil-101-oh at different initial concentrations were gradually decrease on the discipline of mil-101-oh > mil-101(cr) (based on unit weight). 4. conclusion in conclusion, a typical mof with high porosity (mil-101) was modified to introduce functional group such as –oh in order to use it for the adsorptive removal of ppcps such as oxybenzone from an aqueous solution. even though the surface area of the virgin mof decreased noticeably, the modified mil-101 was very effective at the ppcps adsorption. mil-101-oh showed the highest ppcps uptakes based on weight and surface area, respectively. finally, mil-101-oh is suggested to be a potential adsorbent for ppcps removal based on competitive adsorption when compared with carbonaceous materials, mesoporous materials [50, 51] and pristine mil-101. references [1] i. k. e. n. evgenidou and d. a. konstantinous, "lambropoulou, occurrence and removal of transformation products of ppcps and illicit drugs in waste waters: a review," science of the total environment, vol. 505, pp. 905-926, 2015. [2] d. zhang, r. m. gersberg, w. j. ng, and s. k. tan, "removal of pharmaceuticals and personal care products in aquatic plantbased systems: a review," environmental pollution, vol. 184, pp. 620-639, 2014. view at google scholar | view at publisher [3] q. bu, b. wang, j. huang, s. deng, and g. yu, "pharmaceuticals and personal care products in the aquatic environment in china: a review," journal of hazardous materials, vol. 262, pp. 189-211, 2013. view at google scholar | view at publisher [4] s. w. nam, c. jung, h. li, m. yu, j. r. v. flora, l. k. boateng, n. her, k. d. zoh, and y. yoon, "adsorption characteristics of diclofenac and sulfamethoxazole to grapheme oxide in aqueous solution," chemosphere, vol. 136, pp. 20-26, 2015. view at google scholar | view at publisher [5] j. a. daneshvar, l. svanfelt, and g. a. kronberg, "weyhenmeyer, winter accumulation of acidic pharmaceuticals in a swedish river," environmental science and pollution research, vol. 17, pp. 908-916, 2010. view at google scholar [6] d. n. bulloch, "occurrence of halogenated transformation products of selected pharmaceuticals and personal care products in secondary and tertiary treated wastewaters from southern california," environmental science & technology, vol. 49, pp. 2044–2051, 2015. [7] c. jung, "removal of endocrine disrupting compounds, pharmaceuticals, and personal care products in water using carbon nanotubes: a review," journal of industrial and engineering chemistry, vol. 27, pp. 1–11, 2015. [8] s. dong, "recent developments in heterogeneous photocatalytic water treatment using visible light-responsive photocatalysts: a review," rsc advances, vol. 5, pp. 14610–14630, 2015. https://scholar.google.com/scholar?hl=en&q=removal%20of%20pharmaceuticals%20and%20personal%20care%20products%20in%20aquatic%20plant-based%20systems:%20a%20review http://dx.doi.org/10.1016/j.envpol.2013.09.009 https://scholar.google.com/scholar?hl=en&q=pharmaceuticals%20and%20personal%20care%20products%20in%20the%20aquatic%20environment%20in%20china:%20a%20review http://dx.doi.org/10.1016/j.jhazmat.2013.08.040 https://scholar.google.com/scholar?hl=en&q=adsorption%20characteristics%20of%20%20diclofenac%20and%20sulfamethoxazole%20to%20grapheme%20oxide%20in%20aqueous%20solution http://dx.doi.org/10.1016/j.chemosphere.2015.03.061 https://scholar.google.com/scholar?hl=en&q=weyhenmeyer,%20winter%20accumulation%20of%20acidic%20pharmaceuticals%20in%20a%20swedish%20river asian review of environmental and earth sciences, 2018, 5(1): 1-7 6 [9] s. d. richardson and t. a. ternes, "water analysis: emerging contaminants and current issues," analytical chemistry, vol. 86, pp. 2813–2848, 2014. view at google scholar | view at publisher [10] c. gadipelly, "pharmaceutical industry wastewater: review of the technologies for water treatment and reuse," industrial & engineering chemistry research, vol. 53, pp. 11571–11592, 2014. [11] k. aribga, a. vinu, y. yamauchi, q. ji, and j. p. hill, "nanoarchitectinics for mesoporous materials," bulletin of the chemical society of japan, vol. 85, pp. 1-32, 2012. [12] a. vinu and k. ariga, "new ideas for mesoporous materials," advanced porous materials, vol. 1, pp. 63-71, 2013. view at google scholar | view at publisher [13] a. vinu, t. mori, and k. ariga, "new families of mesoporous materials," science and technology of advanced materials, vol. 7, pp. 753-771, 2006. [14] k. ariga, y. yamauchi, g. rydzek, q. ji, y. yonamine, k. c. w. wu, and j. p. hill, "layer-by layer nanoarchitectonics: invention, innovation, and evolution," chemistry letters, vol. 43, pp. 36-68, 2014. view at google scholar | view at publisher [15] h. furukawa, k. e. cordova, m. o. keeffe, and o. m. yaghi, "the chemistry and applications of metal-organic frameworks," science, vol. 341, p. 1230444, 2013. view at google scholar [16] q. yang, d. liu, c. zhong, and j. r. li, "development of computational methodologies for metal-organic frameworks and their application in gas separetions," chemical reviews, vol. 113, pp. 8261-8323, 2013. view at google scholar | view at publisher [17] g. ferey, "hybrid porous solids: past, present, future," chemical society reviews, vol. 37, pp. 191–214, 2008. view at google scholar | view at publisher [18] s. h. jhung, n. a. khan, and z. hasan, "analogous porous metal–organic frameworks: synthesis, stability and application in adsorption," cryst eng commun, vol. 14, pp. 7099–7109, 2012. view at google scholar | view at publisher [19] d. d. zu, l. lu, x. q. liu, d. y. zhang, and l. b. sun, "improving hydrothermal stability and catalytic activity of metal-organic frameworks by graphite oxide incorporation," journal of physical chemistry c, vol. 118, pp. 19910-19917, 2014. view at google scholar | view at publisher [20] n. a. khan, z. hasan, and s. h. jhung, "adsorptive removal of hazardous materials using metal–organic frameworks (mofs): a review," journal of hazardous materials, vol. 244–245, pp. 444–456, 2013. view at google scholar | view at publisher [21] q. h. wu, d. h. gong, and j. l. olson, "commensurate adsorption of hydrocarbons and alcohols in microporous metal–organic frameworks," chemical reviews, vol. 112, pp. 836–868, 2012. [22] e. barea, c. montoro, and j. a. r. navarro, "toxic gas removalmetal-organic frameworks for the capture and degradation of toxic gases and vapours," chemical society reviews, vol. 43, pp. 54195430, 2014. view at google scholar | view at publisher [23] b. v. de voorde, b. bueken, j. denayer, and d. de vos, "adsorptive separation on metal-organic frameworks in the liquid phase," chemical society reviews, vol. 43, pp. 5766-5788, 2014. view at google scholar | view at publisher [24] z. hasan, j. w. jun, and s. h. jhung, "sulfonic acid-functionalized mil-101(cr): an efficient catalyst for esterification of oleic acid and vapor-phase dehydration of butanol," chemical engineering journal, vol. 278, pp. 265–271, 2015. view at google scholar | view at publisher [25] k. a. cychosz, a. g. wong-foy, and a. j. matzger, "enabling cleaner fules: desulfurization by adsorption to microporous coordination polymers," journal of the american chemical society, vol. 131, pp. 14538-14543, 2009. view at google scholar | view at publisher [26] n. a. khan, z. hasan, and s. h. jhung, "ionic liquids supported on metal-organic frameworks: remarkable adsorbents for adsorptive desulfuration," chemistry a european journal, vol. 20, pp. 376-380, 2014. view at google scholar [27] z. hasan and s. h. jhung, "facile method to disperse nonporous metal organicframeworks: composite formation with a porous metal organic frameworkand application in adsorptive desulfurization," acs applied materials & interfaces, vol. 7, pp. 10429–10435, 2015. view at google scholar | view at publisher [28] m. maes, m. trekels, m. boulhout, s. schouteden, f. vermoortele, l. alaerts, d. heurtaux, y. k. seo, y. k. hwang, j. s. chang, i. beurroies, r. denoyel, k. temst, a. vantomme, p. horcajada, c. serre, and d. de vos, "selective removal of nheterocyclicaromatic contaminants from fuels by lewis acidic metal–organicframeworks," angewandte chemie international edition, vol. 50, pp. 4210– 4214, 2011. [29] i. ahmed, z. hasan, n. a. khan, and s. h. jhung, "adsorptive denitrogenation of modelfuels with porous metal–organic framework (mof) mil-101 impregnated with phosphotungstic acid: effect of acid site inclusion," journal of hazardous materials, vol. 250–251, pp. 37–44, 2013. view at google scholar | view at publisher [30] i. ahmed, n. a. khan, and s. h. jhung, "graphite oxide/metal–organic framework (mil-101): remarkable performance in the adsorptive denitrogenation of model fuels," inorganic chemistry, vol. 52, pp. 14155–14161, 2013. view at google scholar | view at publisher [31] n. bakhtiari and s. azizian, "adsorption of copper ion from aqueous solution bynanoporous mof-5: a kinetic and equilibrium study," journal of molecular liquids, vol. 206, pp. 114–118, 2015. view at google scholar | view at publisher [32] k. y. a. lin, s. y. chen, and a. p. jochems, "zirconium-based metal organic frameworks: highly selective adsorbents for removal of phosphate from water and urine," materials chemistry and physics, vol. 160, pp. 168–176, 2015. view at google scholar | view at publisher [33] e. haque, j. e. lee, i. t. jang, y. k. hwang, j. s. chang, j. jegal, and s. h. jhung, "adsorptive removal of methyl orange from aqueous solution with metal– organic frameworks, porous chromium-benzenedicarboxylates," journal of hazardous materials, vol. 181, pp. 535–542, 2010. view at google scholar | view at publisher [34] e. haque, j. jun, and s. h. jhung, "adsorptive removal of methyl orange and methylene blue from aqueous solution with a metal– organic framework material, iron terephthalate (mof-235)," journal of hazardous materials, vol. 185, pp. 507–511, 2011. view at google scholar | view at publisher [35] k. y. a. lin and h. a. chang, "ultra-high adsorption capacity of zeolitic imidazoleframework-67 (zif-67) for removal of malachite green from water," chemosphere, vol. 139, pp. 624-631, 2015. view at google scholar | view at publisher [36] m. tong, d. liu, q. yang, s. devautour-vinot, g. maurinb, and c. zhong, "influence of framework metal ions on the dye capture behavior of mil-100 (fe, cr) mof type solids," journal of materials chemistry a, vol. 1, pp. 8534–8537, 2013. view at google scholar | view at publisher [37] j. w. jun, m. tong, b. k. jung, z. hasan, c. zhong, and s. h. jhung, "effect of central metal ions of analogous metal–organic frameworks on adsorption of organoarsenic compounds from water: plausible mechanism of adsorption and water purification," chemistry a european journal, vol. 21, pp. 347–354, 2015. view at google scholar | view at publisher [38] b. k. jung, j. w. jun, z. hasan, and s. h. jhung, "adsorptive removal of p-arsanilic acidfrom water using mesoporous zeoliticimidazolate framework-8," chemical engineering journal, vol. 267, pp. 9–15, 2015. view at google scholar | view at publisher [39] e. y. park, z. hasan, n. a. khan, and s. h. jhung, "adsorptive removal of bisphenol-afrom water with a metal–organic framework, a porous chromium benzene dicarboxylate," journal of nanoscience and nanotechnology, vol. 13, pp. 2789–2794, 2013. view at google scholar | view at publisher [40] m. zhou, y. wu, j. qiao, j. zhang, a. mcdonald, g. li, and f. li, "the removal of bisphenol-a from aqueous solutions by mil53(al) and meso-structured mil53(al)," journal of colloid and interface science, vol. 405, pp. 157–163, 2013. view at google scholar | view at publisher [41] z. hasan, j. jeon, and s. h. jhung, "adsorptive removal of naproxen and clofibric acid from water using metal–organic frameworks," journal of hazardous materials, vol. 209–210, pp. 151–157, 2012. view at google scholar | view at publisher [42] y. hu, c. song, j. liao, z. huang, and g. li, "water stable metal–organic framework packed micro column for online sorptive extraction and direct analysis of naproxen and its metabolite from urine sample," journal of chromatography a, vol. 1294, pp. 17–24, 2013. view at google scholar | view at publisher [43] z. hasan, e. j. choi, and s. h. jhung, "adsorption of naproxen and clofibric acid over a metal-organic framework mil-101 functionalized with acidic and basic groups," chemical engineering journal, vol. 219, pp. 537–544, 2013. view at google scholar | view at publisher [44] n. a. khan and s. h. jhung, "phase-transition and phase-selective synthesis of porous chromium-benzene dicarboxylates," crystal growth & design, vol. 10, pp. 1860–1865, 2010. view at google scholar | view at publisher https://scholar.google.com/scholar?hl=en&q=water%20analysis:%20emerging%20contaminants%20and%20current%20issues http://dx.doi.org/10.1021/ac500508t https://scholar.google.com/scholar?hl=en&q=new%20ideas%20for%20mesoporous%20materials http://dx.doi.org/10.1166/apm.2013.1005 https://scholar.google.com/scholar?hl=en&q=layer-by%20layer%20nanoarchitectonics:%20invention,%20innovation,%20and%20evolution http://dx.doi.org/10.1246/cl.130987 https://scholar.google.com/scholar?hl=en&q=the%20chemistry%20and%20applications%20of%20metal-organic%20frameworks https://scholar.google.com/scholar?hl=en&q=development%20of%20computational%20methodologies%20for%20metal-organic%20frameworks%20and%20their%20application%20in%20gas%20separetions http://dx.doi.org/10.1021/cr400005f https://scholar.google.com/scholar?hl=en&q=hybrid%20porous%20solids:%20past,%20present,%20future http://dx.doi.org/10.1039/b618320b http://dx.doi.org/10.1039/b618320b https://scholar.google.com/scholar?hl=en&q=analogous%20porous%20metal–organic%20frameworks:%20synthesis,%20stability%20and%20application%20in%20adsorption http://dx.doi.org/10.1039/c2ce25760b https://scholar.google.com/scholar?hl=en&q=improving%20hydrothermal%20stability%20and%20catalytic%20activity%20of%20metal-organic%20frameworks%20by%20graphite%20oxide%20incorporation http://dx.doi.org/10.1021/jp506335x https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20hazardous%20materials%20using%20metal–organic%20frameworks%20(mofs):%20a%20review http://dx.doi.org/10.1016/j.jhazmat.2012.11.011 https://scholar.google.com/scholar?hl=en&q=toxic%20gas%20removal-%20metal-organic%20frameworks%20for%20the%20capture%20and%20degradation%20of%20toxic%20gases%20and%20vapours http://dx.doi.org/10.1039/c3cs60475f https://scholar.google.com/scholar?hl=en&q=adsorptive%20separation%20on%20metal-organic%20frameworks%20in%20the%20liquid%20phase http://dx.doi.org/10.1039/c4cs00006d https://scholar.google.com/scholar?hl=en&q=sulfonic%20acid-functionalized%20mil-101(cr):%20an%20efficient%20catalyst%20for%20esterification%20of%20oleic%20acid%20and%20vapor-phase%20dehydration%20of%20%20butanol http://dx.doi.org/10.1016/j.cej.2014.09.025 http://dx.doi.org/10.1016/j.cej.2014.09.025 https://scholar.google.com/scholar?hl=en&q=enabling%20cleaner%20fules:%20desulfurization%20by%20adsorption%20to%20microporous%20coordination%20polymers http://dx.doi.org/10.1021/ja906034k https://scholar.google.com/scholar?hl=en&q=ionic%20liquids%20supported%20on%20metal-organic%20frameworks:%20remarkable%20adsorbents%20for%20adsorptive%20desulfuration https://scholar.google.com/scholar?hl=en&q=facile%20method%20to%20disperse%20nonporous%20metal%20organicframeworks:%20composite%20formation%20with%20a%20porous%20metal%20organic%20frameworkand%20application%20in%20adsorptive%20desulfurization http://dx.doi.org/10.1021/acsami.5b01642 https://scholar.google.com/scholar?hl=en&q=adsorptive%20denitrogenation%20of%20modelfuels%20with%20porous%20metal–organic%20framework%20(mof)%20mil-101%20impregnated%20with%20phosphotungstic%20acid:%20effect%20of%20acid%20site%20inclusion http://dx.doi.org/10.1016/j.jhazmat.2013.01.024 https://scholar.google.com/scholar?hl=en&q=graphite%20oxide/metal–organic%20framework%20(mil-101):%20remarkable%20performance%20in%20the%20adsorptive%20denitrogenation%20of%20model%20fuels http://dx.doi.org/10.1021/ic402012d https://scholar.google.com/scholar?hl=en&q=adsorption%20of%20copper%20ion%20from%20aqueous%20solution%20bynanoporous%20mof-5:%20a%20kinetic%20and%20equilibrium%20study http://dx.doi.org/10.1016/j.molliq.2015.02.009 https://scholar.google.com/scholar?hl=en&q=zirconium-based%20metal%20organic%20frameworks:%20highly%20selective%20adsorbents%20for%20removal%20of%20phosphate%20from%20water%20and%20urine http://dx.doi.org/10.1016/j.matchemphys.2015.04.021 https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20methyl%20orange%20from%20aqueous%20solution%20with%20metal–%20organic%20frameworks,%20porous%20chromium-benzenedicarboxylates http://dx.doi.org/10.1016/j.jhazmat.2010.05.047 https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20methyl%20orange%20and%20methylene%20blue%20from%20aqueous%20solution%20with%20a%20metal–organic%20framework%20material,%20iron%20terephthalate%20(mof-235) https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20methyl%20orange%20and%20methylene%20blue%20from%20aqueous%20solution%20with%20a%20metal–organic%20framework%20material,%20iron%20terephthalate%20(mof-235) http://dx.doi.org/10.1016/j.jhazmat.2010.09.035 https://scholar.google.com/scholar?hl=en&q=ultra-high%20adsorption%20capacity%20of%20zeolitic%20imidazoleframework-67%20(zif-67)%20for%20removal%20of%20malachite%20green%20from%20water http://dx.doi.org/10.1016/j.chemosphere.2015.01.041 https://scholar.google.com/scholar?hl=en&q=influence%20of%20framework%20metal%20ions%20on%20the%20dye%20capture%20behavior%20of%20mil-100%20(fe,%20cr)%20mof%20type%20solids http://dx.doi.org/10.1039/c3ta11807j https://scholar.google.com/scholar?hl=en&q=effect%20of%20central%20metal%20ions%20of%20analogous%20metal–organic%20frameworks%20on%20adsorption%20of%20%20organoarsenic%20compounds%20from%20water:%20plausible%20mechanism%20of%20adsorption%20and%20water%20purification http://dx.doi.org/10.1002/chem.201404658 https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20p-arsanilic%20acidfrom%20water%20using%20%20mesoporous%20zeoliticimidazolate%20framework-8 http://dx.doi.org/10.1016/j.cej.2014.12.093 https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20bisphenol-afrom%20water%20with%20a%20metal–organic%20framework,%20a%20porous%20chromium%20benzene%20dicarboxylate https://scholar.google.com/scholar?hl=en&q=adsorptive%20removal%20of%20bisphenol-afrom%20water%20with%20a%20metal–organic%20framework,%20a%20porous%20chromium%20benzene%20dicarboxylate http://dx.doi.org/10.1166/jnn.2013.7411 https://scholar.google.com/scholar?hl=en&q=the%20removal%20of%20bisphenol-a%20from%20aqueous%20solutions%20by%20mil-53(al)%20and%20meso-structured%20mil-%2053(al) http://dx.doi.org/10.1016/j.jcis.2013.05.024 https://scholar.google.com/scholar?hl=en&q=dsorptive%20removal%20of%20naproxen%20and%20clofibric%20acid%20from%20water%20using%20metal–organic%20frameworks http://dx.doi.org/10.1016/j.jhazmat.2012.01.005 https://scholar.google.com/scholar?hl=en&q=water%20stable%20metal–organic%20framework%20packed%20%20micro%20column%20for%20online%20sorptive%20extraction%20and%20direct%20analysis%20of%20naproxen%20and%20its%20metabolite%20from%20urine%20sample http://dx.doi.org/10.1016/j.chroma.2013.04.034 https://scholar.google.com/scholar?hl=en&q=adsorption%20of%20naproxen%20and%20clofibric%20acid%20over%20a%20metal-organic%20framework%20mil-101%20functionalized%20with%20acidic%20and%20basic%20groups http://dx.doi.org/10.1016/j.cej.2013.01.002 http://dx.doi.org/10.1016/j.cej.2013.01.002 https://scholar.google.com/scholar?hl=en&q=phase-transition%20and%20phase-selective%20synthesis%20of%20porous%20chromium-benzene%20dicarboxylates http://dx.doi.org/10.1021/cg901562d asian review of environmental and earth sciences, 2018, 5(1): 1-7 7 [45] d. y. hong, y. k. hwang, c. serre, g. ferey, and j. s. chang, "porous chromium terephthalate mil-101 with coordinatively unsaturated sites: surface functionalization, encapsulation, sorption and catalysis," advanced functional materials, vol. 19, pp. 1537– 1552, 2009. view at google scholar | view at publisher [46] b. lev, d. ying, w. huimeng, s. a. scott, and a. alan hatton, "chromium (iii) terephthalate metal organic framework (mil101): hk-free synthesis, structure, polyxometalate composites and catalytic properties," chemistry of materials, vol. 24, pp. 16641675, 2012. view at google scholar | view at publisher [47] y. k. hwang, d. y. hong, j. s. chang, s. h. jhung, y. k. seo, j. kim, and g. férey, "amine grafting on coordinatively unsaturated metal centers of mofs: consequences for catalysis and metal encapsulation," angewandte chemie, vol. 120, pp. 4212-4216, 2008. [48] w. d. yang, c. y. liu, z. y. zhang, y. liu, and s. d. nie, "one step synthesis of uniform organic silver ink drawing directly on paper substrates," journal of materials chemistry, vol. 22, pp. 23012–23016, 2012. view at google scholar | view at publisher [49] y.-s. ho, "second-order kinetic model for the sorption of cadmium onto tree fern: a comparison of linear and non-linear methods," water research, vol. 40, pp. 119–125, 2006. view at google scholar | view at publisher [50] y. onal, c. a. başar, and c. sarıcı-ozdemir, "elucidation of the naproxen sodium adsorption onto activated carbon prepared from waste apricot: kinetic, equilibrium and thermodynamic characterization," journal of hazardous materials, vol. 148, pp. 727–734, 2007. view at google scholar | view at publisher [51] z. i̇lbay, s. şahin, o. kerkez, and ş. s. bayazit, "isolation of naproxen from wastewater using carbon-based magnetic adsorbents," international journal of environmental science and technology, vol. 12, pp. 3541–3550, 2015. view at google scholar | view at publisher asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=porous%20chromium%20terephthalate%20mil-101%20with%20coordinatively%20unsaturated%20sites:%20surface%20functionalization,%20encapsulation,%20sorption%20and%20catalysis http://dx.doi.org/10.1002/adfm.200801130 https://scholar.google.com/scholar?hl=en&q=chromium%20(iii)%20terephthalate%20metal%20organic%20framework%20(mil-101):%20hk-free%20synthesis,%20structure,%20polyxometalate%20composites%20and%20catalytic%20properties http://dx.doi.org/10.1021/cm2034382 https://scholar.google.com/scholar?hl=en&q=one%20step%20synthesis%20of%20uniform%20organic%20silver%20ink%20drawing%20directly%20on%20paper%20substrates http://dx.doi.org/10.1039/c2jm34264b https://scholar.google.com/scholar?hl=en&q=second-order%20kinetic%20model%20for%20the%20sorption%20of%20cadmium%20onto%20tree%20fern:%20a%20comparison%20of%20linear%20and%20non-linear%20methods http://dx.doi.org/10.1016/j.watres.2005.10.040 https://scholar.google.com/scholar?hl=en&q=elucidation%20of%20the%20naproxen%20sodium%20adsorption%20onto%20activated%20carbon%20prepared%20from%20waste%20apricot:%20kinetic,%20equilibrium%20and%20thermodynamic%20characterization http://dx.doi.org/10.1016/j.jhazmat.2007.03.037 https://scholar.google.com/scholar?hl=en&q=isolation%20of%20naproxen%20from%20wastewater%20using%20carbon-based%20magnetic%20adsorbents http://dx.doi.org/10.1007/s13762-015-0775-4 38 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 38-46, 2019 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.38.46 © 2019 by the authors; licensee asian online journal publishing group a novel mpthp modified glassy carbon sensor electrode: investigation of electrochemical behaviors and determination of cu (ii) ions in drinking water sample ayşegül adir1 ecir yilmaz2 ayşen demir mülazımoğlu3 bedrettin mercimek4 alaaddin çukurovalı5 i̇brahim yilmaz6 ibrahim ender mülazımoğlu7 ( corresponding author) 1,2,3,4,7necmettin erbakan university, ahmet keleşoğlu education faculty, chemistry department, konya, turkey. 5fırat university, science faculty, chemistry department, elazığ, turkey. 6karamanoğlu mehmetbey university, kamil özdağ science faculty, chemistry department, karaman, turkey. abstract in the present work report, 2-methyl-6-((2-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2yl)hydrazono)methyl) phenol (mpthp) has been newly synthesized and characterized. the new molecule has been used to modify the glassy carbon (gc) electrode surface through the alcohol oxidation method due to –oh group on its structure. mpthp modified gc (mpthp/gc) electrode has been used as a chemical sensor electrode for the quantitative determination of cu (ii) ions. following the modification process, the surface characterization process of the modified electrode has been carried out by cyclic voltammetry (cv), electrochemical impedance spectroscopy (eis) and scanning electron microscopy (sem). in this work, cu (ii) ions have been quantitatively determined by using differential pulse voltammetry (dpv) technique. a quite low detection limit (based on 3sbl/m) for cu (ii) using developed sensor electrode was found to be as 1.0x10-9 m. for the calibration curve, solutions of cu (ii) ions changing from 1.0x10-9 m to 1.0x10-3 m have been prepared using britton-robinson (br) buffer solution at ph 5. the developed sensor electrode has been applied to tap water sample for the quantitation of cu (ii) ions and the amount of cu (ii) was determined as 4.07 x 10-9 m in this sample. keywords: mpthp, cu (ii) ions, chemical sensor electrode, differential pulse voltammetry, drinking water sample, glassy carbon. citation | ayşegül adir; ecir yilmaz; ayşen demir mülazımoğlu; bedrettin mercimek; alaaddin çukurovalı; i̇brahim yilmaz; ibrahim ender mülazımoğlu (2019). a novel mpthp modified glassy carbon sensor electrode: investigation of electrochemical behaviors and determination of cu (ii) ions in drinking water sample. asian review of environmental and earth sciences, 6(1): 38-46. history: received: 6 august 2019 revised: 10 september 2019 accepted: 16 october 2019 published: 4 december 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: authors would like to thank to the research foundation of necmettin erbakan university, konya, turkey (bap-131210012) for financial support of this work. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 39 2. experimental ..................................................................................................................................................................................... 39 3. results and discussion ................................................................................................................................................................... 40 4. conclusion ......................................................................................................................................................................................... 45 references .............................................................................................................................................................................................. 45 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.38.46&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 https://www.asianonlinejournals.com/index.php/arees/article/view/1141 https://orcid.org/0000-0001-8074-3987 https://orcid.org/0000-0003-1228-0209 https://orcid.org/0000-0001-5780-3056 https://orcid.org/0000-0002-8110-9459 https://orcid.org/0000-0002-8297-2350 https://orcid.org/0000-0002-9447-3065 https://orcid.org/0000-0003-1676-2870 asian review of environmental and earth sciences, 2019, 6(1): 38-46 39 © 2019 by the authors; licensee asian online journal publishing group contribution of this paper to the literature in the present work report, 2-methyl-6-((2-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2yl)hydrazono)methyl) phenol (mpthp) has been newly synthesized and characterized. 1. introduction variety of metal is present in nature. some of them are called heavy metals due to high atomic weight and high density at least 5 times than water [1]. heavy metals may exist naturally almost in every created body. they have a great importance due to their existence in the center of enzymes and hormones. copper is a member of heavy metals. so copper is indispensable for nutrition, it functions as a cofactor in at least 30 essential enzymes [2]. on the other hand, the maximum tolerable daily intake is 0.5 mg kg-1 body weight for copper [3]. if maximum daily intake amount is exceeded, enzymes structure is disrupted which may results in unwanted reactions that may cause toxic effects in living metabolism [4-7]. the concentration of copper varies in soil and water [8]. therefore determination and monitoring of copper is vital for the good of all mankind. to develop an easy, fast and more accurate method for the determination of copper at trace level is a great importance in all kinds of samples. in spite of the fact that, many methods such as inductively coupled plasma mass spectroscopy (icp-ms), graphite furnace atomic absorption spectroscopy (gf-aas) and neutron activation analysis (naa) are present for trace determination of copper, they either require pre-concentration step or are too expensive for using in routine analysis [3, 9]. thus, electroanalytical methods are quite promising among the analytical methods due to being more accurate, easy and fast in measurements. at the beginning of the nineteenth century hugo schiff has claimed that condensation between an amine compound and an aldehyde compound resulting in a new compound that binds to or coordinates with metals [10]. after that schiff bases have been worked on by many researchers. these works show that schiff bases can be used for many purposes [11] such as biosensors [12] optic sensors [13], electro-catalytic [14], antimicrobial [15] inhibitors of corrosion [16]. besides their sensitivity, metal can lead to electrochemical characterization of many biometalomolecules and metalomolecules [17-19]. these type of compounds having metal atoms in their structure can be easily characterized and determined by using electrochemical methods especially voltammetry techniques [20, 21]. in these techniques, applied reduction and oxidation potential must be determined depending on the metal atoms on the schiff base structure especially when using gc electrode. from the obtained peak half-wave potential and redox potential of the metal can be deduced. the aim of this work is; 1) to determine the electrochemical properties of newly synthesized mpthp figure 1 on gc electrode, 2) to develop a simple, highly sensitive, accurate and environmentally friendly method for copper determination in various matrices. figure-1. molecular structure of 2-methyl-6-((2-(4-(3-methyl-3-phenylcyclobutyl) thiazol-2-yl)hydrazono)methyl)phenol (mpthp). 2. experimental 2.1. chemicals all chemicals which were used in experiments obtained from merck, fluka, riedel and sigma-aldrich. all chemicals were analytical grade and were used without further purification processes. mpthp is an original compound which was synthesized by our research group. ultrapure quality water with a resistivity of 18.2 mω cm (millipore milli-q purification system, millipore corp. bedford, ma, usa) was used throughout the experiments in all steps. the solutions for the characterization, analysis and the modification processes were prepared as follow: for non-aqueous medium studies; the solutions were 1mm in 100 mm tetrabuthylammonium tetrafluoroborate (nbu4bf4) in acetonitrile (ch3cn) and ferri/ferrocyanide (fe(cn)6 3−/4−) redox probe mixture (1:1) in 100 mm kcl solution for aqueous medium. the used br buffer solutions were prepared with specific proportions of h3po4, ch3cooh and h3bo3 compounds according to the literature [22, 23] and then ph was adjusted by dropwise addition of 0.2 m or 1 m naoh with a digital jenway 3010 ph meter (staffordshire, uk). 2.2. electrodes and apparatus all experiments were carried out with traditional three electrode systems for all electrochemical and spectroelectrochemical studies. electrochemical measurements were made using gamry reference pci4/750 series potentiostat/galvanostat/zra from gamry instruments (pa, usa). the working gc electrode has 0.071 cm2 geometric area and was purchased from bas (bioanalytical systems, west lafayette, in, usa) model mf-2012. the reference electrodes were the ag/ag+ (10 mm agno3) (bas model mf-2042) for non-aqueous asian review of environmental and earth sciences, 2019, 6(1): 38-46 40 © 2019 by the authors; licensee asian online journal publishing group medium and the ag/agcl/3 m kcl (bas model mf-2063) for aqueous medium. pt wire (bas model mw-1032) was used as a counter electrode. all electrochemical experiments were performed with using a bas model c3 cell stand (in, usa) at room temperature and also the electrodes were kept in ch3cn when they were not in use. the experiments with the cv technique were carried out phe200 physical electrochemistry software (pa, usa). eis was employed with eis300 electrochemical impedance spectroscopy software (pa, usa). swv and dpv techniques were also used with pv220 pulse voltammetry software (pa, usa). the morphology of the electrode surfaces was studied using scanning electron microscope (sem) (carl zeiss ls10 series sem, missouri, usa). 2.3. cleaning and polishing of working electrodes the gc electrodes were polished to obtain a mirror-like appearance, first with fine wet emery paper (grain size 4000) and then with 1.0 μm and 0.3 μm alumina slurry on micro cloth pads (buehler, usa) for all experiments. after that; the gc electrodes were re-polished with 0.05 μm alumina slurry. the gc electrodes were orderly kept in sonicator filled with water, in 1:1 (v/v) isopropyl alcohol (ipa) and ch3cn (ipa + ch3cn) mixture for 10 min before each step [22-26]. 2.4. synthesis and characterization of mpthp the compound was synthesized as shown in figure 2 by the following procedure. to a solution of 2-hydroxy3-methylbenzaldehyde (1.3615 g, 10 mmol) in 50 ml of ethanol, thiosemicarbazide (0.9114 g, 10 mmol) was added portions by monitoring the reaction course with ir spectroscopy. subsequently, a solution of 1-methyl-1-phenyl-3(2-chloro-1-oxoethyl) cyclobutane (α-chloroketone) (2.2271 g, 10 mmol) in 20 ml of absolute ethanol was added. after the addition of the -haloketone, the temperature was raised to 50-55 ºc and kept at this temperature for 2 h. the solution was cooled to room temperature and then made alkaline with an aqueous solution of nh3 (5%), and yellow precipitate separated by suction, washed with aqueous nh3 solution several times, filtered and crystallized from ethanol. yield: 81%, melting point: 440.5 k. characteristic ir bands: –oh absorption of the compound could not been identified. 3118 cm-1 (n-h), 2961-2781 cm-1 (aliphatics), 1613 (c=n azomethine), 1691 cm-1 (c=n thiazole), 1563 (c=c), 1009 cm-1 (c-o), 704 cm-1 (c-s-c thiazole). characteristic 1h nmr shifts (cdcl3, , ppm): 1.47 (s, 3h, -ch3 on cyclobutane), 2.33 (s, 3h, -ch3 on benzaldehyde ring), 2.49 (d, j = 8.8 hz, 4h, -ch2in cyclobutane), 3.58 (q, j = 9.1 hz, 1h, >c-h on cyclobutane), 6.07 (d, j = 1.1 hz, 1h, =ch-s in thiazole ring), 6.81 (t, j = 7.3 hz, 1h, aromatic), 7.00 (dd, j1= 1.1 hz, j2= 7.9 hz, 1h, aromatic), 7.11-7.19 (m, 5h, aromatics plus –nh), 7.26-7.32 (m, 2h, aromatics), 10.78 (s, 1h, –oh). characteristic 13c nmr shifts (cdcl3, , ppm): 169.56, 156.24, 151.93, 151.52, 148.48, 132.48, 128.52, 128.35, 126.08, 125.75, 124.81, 119.34, 117.50, 99.79, 40.21, 39.19, 30.29, 29.95, 15.93. figure-2. synthetic pathway for the synthesis of the target compound. 3. results and discussion due to the toxicity and excessive amounts of cu (ii) ions in nature; quantitative detection of cu (ii) is essential and many techniques are available in the literature for this purpose. especially; after the researchers have realized that carbon electrode can be modified with a variety of organic compounds, intensive study has been going on in this field. most of these studies appear to be electrochemical investigation [27-29]. whereas our aim is to detect environmentally toxic metals firstly by synthesizing a compound that is sensitive to one of these metals and then, graft this molecule onto the gc electrode surface [30]. schiff bases play an important role about chelation of metal ions. for this reason we have synthesized a schiff base for the quantitation of cu (ii) ions. 3.1. electrochemical grafting of mpthp on to the gc electrode surface electrochemical modification technique which has an important of increasing every day, is the first step in the production of a sensor electrode for quantitative determination of different organic and inorganic species. electrochemical modifications can be made basically in three ways. the first one is the reduction of diazonium salts which is the most stable and practical method [31-33]. the other two are alcohol [34, 35] and amine [22, 23] oxidation methods. the current work proposes to develop a sensor electrode for the determination of cu (ii) ions the natural sample. the gc electrode surface was modified with mpthp via alcohol oxidation method using cv technique in non-aqueous medium. the modification process was carried out between +300 mv and +2600 mv potential range, under 100 mv s-1 scan rate with using 10 cycles. mpthp solution used in modification process was 1 mm and was prepared in 100 mm nbu4bf4 (in ch3cn) supporting electrolyte solution. the modification voltammogram and binding mechanism of mpthp molecule on the gc electrode surface were given in figure 3 and figure 4, respectively. asian review of environmental and earth sciences, 2019, 6(1): 38-46 41 © 2019 by the authors; licensee asian online journal publishing group figure-3. cyclic voltammogram of 1 mm mpthp in ch3cn containing 100 mm nbu4bf4 vs. ag/ag+/(10 mm agno3) onto the gc electrode. potential range from +300 mv to +2600 mv, scan rate is 100 mv s-1. figure-4. modification mechanism of mpthp at gc electrode surface (in ch3cn containing 100 mm nbu4bf4). the first peak in figure 3 is the oxidation peak of the molecule owing to the removing of one proton from the molecule. the peak number 3 is the binding of the molecule on the gc electrode surface forming c-o-c bond on the oxygen tail. as it can be seen from the peak in figure 3; the mpthp molecule binds after the second cycle but modification processes was performed using 10 cycles. the reasons for that no pin holes remain on the gc surface and thus, more stable and smooth surface was obtained with mpthp. 3.2. surface characterization of mpthp/gc electrode surface characterization process is the second important step in the electrochemical studies. for this purpose varying electrochemical, spectroscopic and microscopic techniques could be utilized. in the current study; the cv technique was used for surface characterizations as an electrochemical characterization technique, eis was used as a spectroelectrochemical technique and sem technique was employed for microscopic surface characterizations. 3.3. characterization of mpthp/gc electrode surface by cv and eis the surface characterization processes for both the bare gc and the modified gc electrodes were carried out using cv, eis and sem techniques in both aqueous and non-aqueous media. the cv electrode characterization technique was performed in the presence of hexacyanoferrate (iii), fe(cn)6 3−, in ph 2.0 br buffer solution and 1.0 mm of ferrocene solution in ch3cn containing 100 mm nbu4bf4 as a supporting electrolyte. in non-aqueous medium studies, ferrocene solution was used in the potential range from −200 mv to +400 mv figure 5a and fe(cn)6 3− solution in ph 2 br buffer solution was applied in the potential range from +600 mv to 0.00 mv in aqueous medium experiments figure 5b at a sweep rate of 100 mv s−1 in the characterization process with cv technique. the cyclic voltammograms of modified and bare gc electrodes were compared with ferrocene and fe(cn)6 3− redox probes. for the characterization with eis, the measurements were recorded in a wide frequency range from 100.000 hz to 0.05 hz in 1 mm equiv. molar ratio of fe(cn)6 3−/fe(cn)6 4− in 100 mm kcl and the nyquist plots were drawn. the nyquist plots of modified electrodes were overlaid eis data of the bare gc electrode figure 5c. all potentials are referenced to ag/agcl/(3 m kcl) for aqueous medium and ag/ag+/(10 mm agno3) for non-aqueous medium. asian review of environmental and earth sciences, 2019, 6(1): 38-46 42 © 2019 by the authors; licensee asian online journal publishing group it is shown in figure 5a, the standard anodic and cathodic peaks of ferrocene redox probe were obtained on both the bare gc electrode surface figure 5aa and mpthp modified gc electrode surface figure 5ab in oxidation and reduction directions, respectively. this is the expected case for mpthp/gc electrode surface. in the second step of cv characterization process is the one held with fe(cn)6 3redox probe in aqueous medium. according to the characterization process is practiced using fe(cn)6 3redox probe, the obtained surface is more electro-inactive than the bare gc electrode surface. this result could be easily deduced from the decrease of anodic and cathodic peak currents. the obtained active mpthp/gc electrode surface is shown in figure 5bb in the order of the bare gc electrode surface given in figure 5ba. it can be derived from the used characterization process using cv technique that mpthp/gc electrode surface can be used as a sensor electrode. in the electrochemical studies; eis is very suitable technique for the examination of surface properties. it is capable of giving valuable data about defects/holes of the modified surface, the kinetics and the mechanism of the surface developing processes, surface coverage, and so forth. the eis graphs of bare gc and mpthp/gc electrode surfaces were displayed in figure 5c. the figure 5cb shows that mpthp/gc electrode surface allows the electron transfer at nearly 80 kohm resistance. on the other hand, the electron transfer concession is at about 2 kohm resistance for bare gc electrode surface figure 5ca. the results of surface characterization studies done by eis are consistent with the ones obtained from the cv characterization process. the solution resistance (rs), the charge transfer resistance (rct), constant value (y0) and the constant phase element (cpe) and exponent (α) are the basic elements of equivalent circuit. the experimental impedance values are proved with the randles equivalent circuit simulation using gamry eis300 electrochemical impedance spectroscopy software. according to the data obtained from the characterization processes, it can be concluded that mpthp molecule is grafted on the gc electrode surface in non-aqueous medium. eis is a valuable method to observe the impedance changes of the electrode surface during the modification process. the semicircle diameter of nyquist plot reflects the rct is from the electron transfer of the redox probe fe(cn)6 3-/fe(cn)6 4solution and figure 5c put in the eis of bare gc figure 5ca and mpthp/gc figure 5cb electrodes. firstly; the value of rct was recorded as 1.530x103 ω on the bare gc electrode surface. secondly bare gc electrode surface was modified with mpthp-das molecule, the value of rct that is much smaller than that of bare gc reduced to 810 ω. this low rct value was obtained because of the existence of high conductive mpthp/gc electrode surface. a nearly straight line was achieved with the rct value close to zero, proving that mpthp/gc electrode taken part the electro-active layer for mass and electron transfer and also interfered the diffusion of ferricyanide toward the electrode surface. the simulation was made for the result plot to recommend an equivalent circuit model (based cpe) thanks to the calculated parameters rct=810.0 ω s, rs=130.2 ω s, yo=3.6x10−6 s, α=0.820. figure-5. overlaying cyclic voltammograms for a) 1mm ferrocene redox probe solution vs. ag/ag+ (10 mm) in ch3cn containing 100 mm nbu4bf4 using 100 mv s-1 scanning rate b) 1 mm fe(cn)6 3redox probe solution vs. ag/agcl/3 m kcl reference electrode in br buffer solution, ph= 2 using 100 mv s-1 scanning rate and c) nyquist plot for electrochemical impedance spectra of 1 mm fe(cn)6 3−/4− redox couple solution in 100 mm kcl at the frequency range of 100.000–0.05 hz at 10 mv wave amplitude. equation 1 was used to determine the electron transfer rate constant, k0, for fe(cn)6 3−/fe(cn)6 4− for bare gc and mpthp/gc electrode surfaces. ( ) (1) asian review of environmental and earth sciences, 2019, 6(1): 38-46 43 © 2019 by the authors; licensee asian online journal publishing group in this equation, a is the electrode area (cm2); n is number of electrons needed for ox/red of fe(cn)6 3−/fe(cn)6 4− mixed solution system; c (mole cm-3) is the molar concentration of fe(cn)6 3−/fe(cn)6 4−; r (8.314 j mol-1 k-1) is the ideal gas constant, t (k) is the temperature; f (96485 c mol-1) is the faraday constant [42]. respectively, the values for k0 were computed as 2.45x10−6 cm s-1, 4.63x10−6 cm s-1 for bare gc and mpthp/gc electrodes. in addition, to the covered electrode area was calculated according to equation 2, ( ) (2) here, is the charge transfer resistance of the bare gc electrode while is the charge transfer resistance of the mpthp/gc electrodes and θ is the modified area by mpthp molecule. surfaces are gained with superimposing of the nyquist plots of related electrode surfaces. from the results given in the nyquist plot, it was obtained that eis signal is equivalent to 82.00% coverage of the gc surface. obtained of rct values of the nyquist plots figure 5c for 1.0 mm fe(cn)6 3−/fe(cn)6 4− solution (in 100 mm kcl) at the (a) bare gc and (b) mpthp/gc electrodes. 3.4. microscopic characterizations of mpthp/gc electrode surface the morphology studies of mpthp film on gc electrode were carried out with sem technique. this technique was employed to confirm the studies obtained using cv and eis. the images of bare gc and mpthp/gc electrode surfaces were recorded and shown in figure 6. figure-6. sem images of a) bare gc and b) mpthp/gc. here, figure 6a and figure 6b reveal smooth surfaces which owing to the bare gc figure 6a and the modified surface which owing to mpthp/gc figure 6b electrode surfaces. these obtained data of the microscopic surface characterization are the proof of successive modification of the surfaces. 3.5. the use of mpthp/gc electrode as a sensor electrode making use of the chemical sensor electrode which is obtained using electrochemical methods is frequently operated in the recent years for the quantitative determination of organic and inorganic species. the main reasons of preference of these methods can be counted as getting rapid and reliable results, being relatively low cost, providing less sample consumption and reaching low detection limit. in this study, the developed mpthp/gc electrode is used for the quantitative determination of cu (ii) ions in tap water. for this aim; firstly the response of mpthp/gc electrode against cu (ii) ions was examined using swv and dpv techniques. the obtained voltammograms are given in figure 7. figure-7. swvs (a) and dpvs (b) of 1×10−3 m cu (ii) solution onto the mpthp/gc electrode surface. asian review of environmental and earth sciences, 2019, 6(1): 38-46 44 © 2019 by the authors; licensee asian online journal publishing group from the obtained voltammograms in figure 7a (for swv) and figure 7b (for dpv), peak values are quite big and thus both methods could be used for the quantitative determination of cu (ii) ions in natural sample. 3.6. setting of optimum incubation time according to the literature, the quantitative analysis of cu (ii) ions is performed spectroscopically and electrochemically around ph 5. based on this information, 1 mm solution of cu (ii) ions was prepared in ph 5 br buffer solution. the modified electrode was immensely kept in cu (ii) solution for different time period (30, 60, 90, 120 minutes) to determine the optimum complexation time. after that, the voltammograms were obtained from the scan between -400 mv to +400 mv potential range using dpv and swv techniques figure 8. the measured peak currents from the fig 5 were plotted against the incubation time. as seen in both voltammograms in fig 5, the most appropriate incubation time for quantitative determination of cu (ii) ions natural samples are defined as 90 minutes. figure-8. dpvs (a) and swvs (b) of various incubation time periods of 1×10−3 m cu (ii) solution onto the mpthp/gc electrode surface the measurements a) supporting electrolyte, b) 30, c) 60, d) 90 and e) 120 min were performed in br buffer solution, ph 5.0, vs. ag/agcl/(3 m kcl). 3.7. the using of mpthp/gc sensor electrode in cu (ii) ions determination by dpv although we were able to use both swv (1x10-5 m) and dpv (1x10-9 m) techniques, we have chosen dpv technique owing to the high sensitivity. after modification and characterization steps, the developed mpthp/gc sensor electrode has become available for the detection of cu (ii) ions under the optimum ph and incubation time. a calibration curve was drawn using standard concentration and peak current values read from voltammograms. for this purpose; 1000 ppm cu (ii) ion stock solution was used to prepare a series of standards in the range of 1.0x10-3 m to 1.0x10-9 m in br buffer solution (ph 5). following this step, the designed mpthp/gc sensor electrode was put in each standard solution of copper for 90 minutes. after completion of the complexation process, the measured voltammograms were recorded and shown in figure 9a. the sketched calibration curve is shown in figure 9b. figure-9. a. dpvs of different concentrations of standard cu (ii) solution onto the mpthp/gc electrode surface a) 1×10−3, b) 1×10−4, c) 1×10−5, d) 1×10−6, e) 1×10−7, f) 1×10−8 and g) 1×10−9, the measurements were performed in br buffer solution, ph 5.0, vs. ag/agcl/(3 m kcl). b) standard calibration curve for the cu (ii) ions. low level of cu (ii) ions in tap water were quantitatively determined using the calibration curve. 10 ml of tap water sample was mixed with 10 ml ph 5 br buffer solution. the mixture was then used for all measurements of cu (ii) amounts in drinking water. the dpv voltammograms are shown in figure 10. by using calibration curve, the amount of cu (ii) was determined as 4.07 x 10-9 m in drinking water sample. asian review of environmental and earth sciences, 2019, 6(1): 38-46 45 © 2019 by the authors; licensee asian online journal publishing group figure-10. differential pulse voltammogram of cu (ii) ions in drinking water sample onto the mpthp/gc electrode surfaces. the measurement was performed in br buffer, ph 5.0, potential is referred vs. ag/agcl/(3 m kcl). after the analysis; the estimated reaction mechanism for mpthp/gc-cu (ii) ion complex on the electrode surface was given figure 11. mainly, cu (ii) ions provide a six coordination complex. the copper ions are interacted with two points. the coordination is completed by four other water molecules. figure-11. a) oxidation of mpthp on gc electrode surface and b) the proposed structure of the complex formed between the mpthp/gc electrode with cu (ii) ion. 4. conclusion the results of this study were achieved with the developed mpthp/gc sensor electrode in which mpthp molecule is originally synthesized by our research team. with this designed sensor electrode cu (ii) ions were determined in tap water providing a low lod. under the optimum experimental conditions, lod was found to be as 1.0x10-9 m (d = 3sbl/m). with high stability and sensitivity, the new fabricated electrode was successfully employed to detect cu (ii) ions in real sample. references [1] j. raj, a. raina, and t. dogra, "direct determination of zinc, cadmium, lead, copper metal in tap water of delhi (india) by anodic stripping voltammetry technique," in e3s web of conferences, 2013, p. 09009. [2] m. b. gholivand, a. sohrabi, and s. abbasi, "determination of copper by adsorptive stripping voltammetry in the presence of calcein blue," electroanalysis: an international journal devoted to fundamental and practical aspects of electroanalysis, vol. 19, pp. 16091615, 2007. available at: https://doi.org/10.1002/elan.200703891. [3] e. shams, a. babaei, and m. soltaninezhad, "simultaneous determination of copper, zinc and lead by adsorptive stripping voltammetry in the presence of morin," acta chemical analytics, vol. 501, pp. 119-124, 2004. available at: https://doi.org/10.1016/j.aca.2003.09.010. [4] j. camakaris, i. voskoboinik, and j. mercer, "molecular mechanisms of copper homeostasis," biochemical and biophysical research communications, vol. 261, pp. 225-232, 1999. [5] r. uauy, m. olivares, and m. gonzalez, "essentiality of copper in humans," the american journal of clinical nutrition, vol. 67, pp. 952s-959s, 1998. available at: https://doi.org/10.1093/ajcn/67.5.952s. [6] s. g. kaler, "metabolic and molecular bases of menkes disease and occipital horn syndrome," pediatric and developmental pathology, vol. 1, pp. 85-98, 1998. available at: https://doi.org/10.1007/s100249900011. [7] a. baker, l. harvey, g. majask-newman, s. fairweather-tait, a. flynn, and k. cashman, "effect of dietary copper intakes on biochemical markers of bone metabolism in healthy adult males," european journal of clinical nutrition, vol. 53, pp. 408-412, 1999. available at: https://doi.org/10.1038/sj.ejcn.1600763. [8] j. opydo, "the determination of zn, cd, pb and cu in soil extracts by anodic stripping voltammetry," water, air, and soil pollution, vol. 45, pp. 43-48, 1989. [9] a. gonzales, m. firmino, c. nomura, f. rocha, p. oliveira, and i. gaubeur, "peat as a natural solid-phase for copper preconcentration and determination in a multicommuted flow system coupled to flame atomic absorption spectrometry," acta chemical analytics, vol. 636, pp. 198-204, 2009. available at: https://doi.org/10.1016/j.aca.2009.01.047. [10] n. aksuner, e. henden, i. yilmaz, and a. cukurovali, "a highly sensitive and selective fluorescent sensor for the determination of copper (ii) based on a schiff base," dyes and pigments, vol. 83, pp. 211-217, 2009. available at: https://doi.org/10.1016/j.dyepig.2009.04.012. [11] c. fengying, l. kezhi, and l. hejun, "synthesis, structural, and electrocatalytic properties of copper (ii) complex of ono donor acylhydrazone and 2-methylimidazole," synthesis and reactivity in inorganic and metal-organic, inorganic and nano-metal chemistry, vol. 44, p. 1029, 2014. asian review of environmental and earth sciences, 2019, 6(1): 38-46 46 © 2019 by the authors; licensee asian online journal publishing group [12] a. d. kulkarni, s. a. patil, and p. s. badami, "sno donor schiff bases and their co (ii), ni (ii) and cu (ii) complexes: synthesis, characterization, electrochemical and antimicrobial studies," journal of sulfur chemistry, vol. 30, pp. 145-159, 2009. available at: https://doi.org/10.1080/17415990802663133. [13] m. rizzi, m. trueba, and s. p. trasatti, "polypyrrole films on al alloys: the role of structural changes on protection performance," synthetic metals, vol. 161, pp. 23-31, 2011. available at: https://doi.org/10.1016/j.synthmet.2010.10.029. [14] z ı nez-arias, m. a. mendiola, and m. t. sevilla, "spectroscopic and electrochemical properties of nickel (ii), iron (iii) and cobalt (ii) complexes with benzilbisthiosemicarbazone—importance of working conditions and the metal salt used in the final complex," polyhedron, vol. 19, pp. 2059-2068, 2000. available at: https://doi.org/10.1016/s02775387(00)00505-2. [15] g. b. bagihalli, p. g. avaji, s. a. patil, and p. s. badami, "synthesis, spectral characterization, in vitro antibacterial, antifungal and cytotoxic activities of co (ii), ni (ii) and cu (ii) complexes with 1, 2, 4-triazole schiff bases," european journal of medicinal chemistry, vol. 43, pp. 2639-2649, 2008. available at: https://doi.org/10.1016/j.ejmech.2008.02.013. [16] a. erçağ, m. şahin, a. koca, and e. bozkurt, "synthesis, characterization, epr, electrochemical, and in situ spectroelectrochemical studies of salen-type oxovanadium (iv) and copper (ii) complexes derived from 3, 4-diaminobenzophenone," journal of coordination chemistry, vol. 66, pp. 1635-1649, 2013. available at: https://doi.org/10.1080/00958972.2013.787530. [17] z z z z ı ı nez, "the structures and cyclic voltammetry of three copper (ii) complexes derived from bulky ortho-hydroxy schiff bases," journal of molecular structure, vol. 612, pp. 69-79, 2002. available at: https://doi.org/10.1016/s0022-2860(02)00106-0. [18] e. franco, e. lópez-torres, m. mendiola, and m. sevilla, "synthesis, spectroscopic and cyclic voltammetry studies of copper (ii) complexes with open chain, cyclic and a new macrocyclic thiosemicarbazones," polyhedron, vol. 19, pp. 441-451, 2000. available at: https://doi.org/10.1016/s0277-5387(99)00383-6. [19] i ü zı ğlu, a. d. mü zı ğ yı z " f q h w electrochemical using 3, 3'-diaminobenzidine modified glassy carbon sensor electrode," desalination, vol. 268, pp. 227-232, 2011. available at: https://doi.org/10.1016/j.desal.2010.10.033. [20] i ü zı ğ yı z "q f h y f paste electrode surface by cyclic voltammetry," desalination, vol. 256, pp. 64-69, 2010. available at: https://doi.org/10.1016/j.desal.2010.02.014. [21] a. d. mulazimoglu, i. e. mulazimoglu, and b. mercimek, "synthesis, characterizations and investigation of electrochemical behaviours of 4-[(2-hydroxyphenylimino) methyl] benzene-1, 3-diol," journal of chemistry, vol. 6, pp. 965-974, 2009. available at: https://doi.org/10.1155/2009/426170. [22] i. e. mulazimoglu, "covalent modification of a glassy carbon surface by electrochemical oxidation of 3, 3'-diaminobenzidine," asian journal of chemistry, vol. 22, p. 8203, 2010. [23] m. zatloukalová, v. křen, r. gažák, m. kubala, p. trouillas, j. ulrichová, and j. vacek, "electrochemical investigation of flavonolignans and study of their interactions with dna in the presence of cu (ii)," bioelectrochemistry, vol. 82, pp. 117-124, 2011. available at: https://doi.org/10.1016/j.bioelechem.2011.06.005. [24] m. etienne, j. bessiere, and a. walcarius, "voltammetric detection of copper (ii) at a carbon paste electrode containing an organically modified silica," sensors and actuators b: chemical, vol. 76, pp. 531-538, 2001. available at: https://doi.org/10.1016/s0925-4005(01)00614-1. [25] g. herzog and d. w. arrigan, "application of disorganized monolayer films on gold electrodes to the prevention of surfactant inhibition of the voltammetric detection of trace metals via anodic stripping of underpotential deposits: detection of copper," analytical chemistry, vol. 75, pp. 319-323, 2003. available at: https://doi.org/10.1021/ac026093f. [26] z. ustündağ and a. o. solak, "edta modified glassy carbon electrode: preparation and characterization," electrochimica acta, vol. 54, pp. 6426-6432, 2009. available at: https://doi.org/10.1016/j.electacta.2009.06.015. [27] a. r. zanganeh and m. k. amini, "polypyrrole-modified electrodes with induced recognition sites for potentiometric and voltammetric detection of copper (ii) ion," sensors and actuators b: chemical, vol. 135, pp. 358-365, 2008. available at: https://doi.org/10.1016/j.snb.2008.09.005 [28] a. o. solak, l. r. eichorst, w. j. clark y " f f ― ‖ h xh conductance switching," analytical chemistry, vol. 75, pp. 296-305, 2003. available at: https://doi.org/10.1021/ac026107h. [29] j. pinson and f. podvorica, "attachment of organic layers to conductive or semiconductive surfaces by reduction of diazonium salts," chemical society reviews, vol. 34, pp. 429-439, 2005. available at: https://doi.org/10.1039/b406228k. [30] i̇ ü zı ğ ü zı ğlu, "investigation of sensitivity against different flavonoid derivatives of aminophenylmodified glassy carbon sensor electrode and antioxidant activities," food analytical methods, vol. 5, pp. 1419-1426, 2012. available at: https://doi.org/10.1007/s12161-012-9393-7. [31] a. k. timbola, c. d. d. souza, c. giacomelli, and a. spinelli, "electrochemical oxidation of quercetin in hydro-alcoholic solution," journal of the brazilian chemical society, vol. 17, pp. 139-148, 2006. available at: https://doi.org/10.1590/s010350532006000100020. [32] p. janeiro and a. m. o. brett, "solid state electrochemical oxidation mechanisms of morin in aqueous media," electroanalysis: an international journal devoted to fundamental and practical aspects of electroanalysis, vol. 17, pp. 733-738, 2005. available at: https://doi.org/10.1002/elan.200403155. [33] d. d. macdonald, "reflections on the history of electrochemical impedance spectroscopy," electrochimica acta, vol. 51, pp. 13761388, 2006. available at: https://doi.org/10.1016/j.electacta.2005.02.107. [34] j.-b. he, y. wang, n. deng, and x.-q. lin, "study of the adsorption and oxidation of antioxidant rutin by cyclic voltammetry– voltabsorptometry," bioelectrochemistry, vol. 71, pp. 157-163, 2007. available at: https://doi.org/10.1016/j.bioelechem.2007.03.003. [35] v. ganesh, s. k. pal, s. kumar, and v. lakshminarayanan, "self-assembled monolayers (sams) of alkoxycyanobiphenyl thiols on gold—a study of electron transfer reaction using cyclic voltammetry and electrochemical impedance spectroscopy," journal of colloid and interface science, vol. 296, pp. 195-203, 2006. available at: https://doi.org/10.1016/j.jcis.2005.08.051. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 9 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 9-17, 2020 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.9.17 © 2020 by the authors; licensee asian online journal publishing group assessment of groundwater quality in coastal region a case study of qayyumabad, karachi, pakistan adnan khan1 syed asad raza2 afrida fatima3 syed wasi haider4 ( corresponding author) 1,2,3department of geology, university of karachi, pakistan. 4institute of space science and technology, university of karachi, pakistan. abstract the aim of present study is to assess groundwater quality of qayyumabad area for drinking purpose. groundwater samples (n = 20) were collected from wellbores from variable depths (12300 feet) occurring on both banks of the malir river near study area. water quality was assessed through estimation of physical parameters including, ph, eh, tds, ec, hardness, temperature, aesthetic character (taste, color and odor) and chemical parameters including major cations (na, k, ca, mg), anions (cl, no₃, so₄, hco₃) and minor/trace elements (fe, as). data revealed that groundwater of study area has very high tds content (range: 805-40340 mg/l) and positive eh (180 to +125 mv), suggesting the recent recharge. the ph varies in the range of 6.55-7.75 which comply with who limit (6.5-8.5) for drinking water. major solutes varied in the order of na (mean: 2587 mg/l) > mg (433mg/l) > ca (231mg/l) > k (91 mg/l) while anions in the order of cl (mean: 3385 mg/l) > so₄ (mean: 580 mg/l) > hco₃ (mean: 343 mg/l) > no₃ (11.43 mg/l). both arsenic and iron contents occur within the who permissible limits except two samples which showed elevated fe (4950 ppb) and as (100 ppb) respectively. these results suggest that groundwater in study area is unfit for drinking purpose. principal component analysis (pca) explained four factors where f1 suggests the salts leaching mechanism and f2 indicated anoxia prevalence due to organic matter decomposition. on the other hand, f3 confirmed water rock interaction and f4 supported the prevalence arsenic release associated with anoxia. keywords: groundwater, shallow aquifers, drinking quality, coastal part, karachi. citation | adnan khan; syed asad raza; afrida fatima; syed wasi haider (2020). assessment of groundwater quality in coastal region a case study of qayyumabad, karachi, pakistan. asian review of environmental and earth sciences, 7(1): 9-17. history: received: 22 october 2019 revised: 25 november 2019 accepted: 30 december 2019 published: 12 february 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: authors are highly thankful to chairperson, department of geology, university of karachi for providing analytical facilities. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 10 2. materials and methods ................................................................................................................................................................... 10 3. results and discussion ................................................................................................................................................................... 11 4. conclusion ......................................................................................................................................................................................... 16 references .............................................................................................................................................................................................. 16 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.9.17&domain=pdf&date_stamp=2017-01-14 https://orcid.org/0000-0002-0706-4168 https://orcid.org/0000-0002-1989-3529 https://orcid.org/0000-0003-1223-2944 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://www.asianonlinejournals.com/index.php/arees/article/view/1311 http://www.asianonlinejournals.com/index.php/arees/article/view/1311 asian review of environmental and earth sciences, 2020, 7(1): 9-17 10 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this paper will integrate the knowledge of groundwater sources occurring in coastal parts of the world where dense population is a common demographic manifestation. it will also provide the insights about river systems occurring in the proximity of sea on groundwater characteristics. 1. introduction water is fundamental need of each individual and it is a privilege of individual to approach drinking safe water. life essentially depends on water and its quality being used on regular basis for different purposes. the water we use is either the river driven which is treated in different plants or the wellbore water which we directly suck from specific depth. however, recently the increasing population is resulting in the acute shortage of municipally supplied water. in order to overcome the demand of water, groundwater is used as an alternative. according to world health organization (who) about 80% diseases are water borne. pakistan is becoming water stressed country and is likely to be water scarce in near future [1]. pakistan positions at number 80 among 122 countries with respect to drinking water quality. drinking water sources, both surface and groundwater are polluted with coliforms, dangerous metals and pesticides all through the nation. major factors of groundwater chemistry are regional geology, geochemical process and land use patterns [2]. the quality of water is greatly influenced by its composition. the major part of dissolved elements in groundwater comes from dissolved minerals in soil and sedimentary rocks. natural filtration through soil and sediments makes the groundwater free from organic impurities [3].on the other hand, seawater intrusion in coastal settings deteriorates the quality by increasing the salt content in groundwater. it becomes a menace where surface water is polluted and the municipal water supply is abandoned or irregular. like many big cities of developing countries, karachi is a coastal city which is expanding every day. the city has a large number of industrial units generating approximately 1.3 million liters of effluents per day with only about 5% of the industrial and domestic waters receiving significant treatment and the rest untreated waste is discharged directly into malir and lyari rivers [4]. coastal part of karachi is by far, the most populous (~10 million inhabitants, as per 1998 census) and the largest industrial (more than 1000 large industrial units) base of pakistan, with a coastline extending up to about 80 km. geomorphically, karachi city lies on hub and malir river basins. shallow aquifers of karachi are mainly recharged by these two rivers. presently, drinking water supply to the metropolitan karachi is maintained through three main sources including (i) indus river (keenjhar lake) (ii) hub river (hub dam) and (iii) groundwater through boring wells. however, increasing population, over-exploitation of groundwater and limited recharge of aquifer system has caused severe decline in water table during the last two decades. the three large industrial areas known as sindh industrial trading estate (site), korangi industrial trading estate (kite) and landhi industrial trading estate (lite) are discharging huge quantities of effluents comprising of organic matter, heavy metals, oil, greases, liquid and solid wastes into malir and lyari rivers. this malpractice is causing severe environmental degradation in various ecosystems of the city. the toxic metals and organic dye containing waste is directly poured into the lyari and malir rivers without any treatment. malir river basin is very important in terms of agricultural activity, transporting municipal and industrial waste to the sea. besides, malir river is main water source recharging the shallow aquifers occurring in its surroundings. it is hypothesized that industrial effluents and municipal wastes being disposed off through mali river is causing the contamination of shallow groundwater by infiltration through aquifer depths. this may lead to hamper the health of resident around mali river. therefore, it is imperative to screen the groundwater around malir river for its quality determination. for this purpose, qayyumabad area was selected as study site due to the fact that it lies at the terminus of malir river where high accumulation of trace elements and other contaminates is expected as compared to the corresponding concentration upstream. moreover, seawater intrusion is also likely to reduce groundwater potability due to excessive salt content. 2. materials and methods 2.1. study area qayyumabad is located (latitude: 24º 49´ 32´´ n, longitude: 67º 05´ 02´´ e) on the western bank of malir river in korangi creek area figure 1. it is a suburb of korangi which is spread over an area of about 109 acre with a dense population (more than 7000 people) of multiple ethnic backgrounds. the residents are provided with municipally supplied water through pipelines but water supply is sporadic and occasionally available. due to over population and damage to water supply line and water theft the problem of fresh water availability is aggravating. as a result, people have switched over to groundwater sources for domestic uses. the area under study lies on south eastern corner of karachi figure 1. geologically, it is marking the southernmost extension of the pab range. gaj formation of miocene age is exposed in study area. the catchment area of malir river is situated in the north of study area [5]. generally water is present at very shallow depth (12-40 feet) due to the fact that watersaturated zones are present within the weathered profile of the rocks or in the recent windblown sands. stable aquifers are present in the terrace deposits of mali river which are 150-200 meters thick. asian review of environmental and earth sciences, 2020, 7(1): 9-17 11 © 2020 by the authors; licensee asian online journal publishing group figure1. sample location map of study area. 2.2. sample collection groundwater samples (n=20) were collected from boring wells at variable depth range (12-300 feet). water samples were collected in plastic bottles of about 1.5 liter by using electrical pumps to run water for 1-2 minutes to get fresh samples of the groundwater for physicochemical analysis. bottles were properly washed and rinsed thoroughly with distilled water and then with groundwater at sampling site to minimize any impurity. locations of the wells were marked on the map with the help of global positioning system (gps). 2.3. sample analysis aesthetic characters (color, taste, odor,) and physical parameters including temperature, and turbidity were measured by thermometer and turbidity meter respectively. the ph and eh of collected samples were measured by using ph meter (adwa ad 111) while tds and ec were determined by using ec meter (adwa ad 330). sodium and potassium were estimated by flame photometer (jenway efp7) while calcium, magnesium, chloride, and bi-carbonate were determined by standard titration method. gravimetric method was used for sulphate determination. nitrate content was estimated by using spectrophotometer (hach-8171) and iron by atomic absorption spectrometer (analyst 400, perkin elmer). arsenic content was determined by colorimetric method using arsenic testing kit (merck). statistical analysis was carried out by using spss software (version 16.00). pca analysis was employed on data set of groundwater parameters including well depth, temperature, ph, eh, tds, ec, hardness, na, k, ca, mg, cl, no₃, so₄, hco₃, fe, and as. 3. results and discussion 3.1. physical parameters physical characteristics of collected groundwater samples have been summarized in table 1. well depth of collected samples ranges between 12-300 feet with a mean of 90 feet table 1. tapping the water from such variable depths is due to various factors including affordability, geological variation of aquifers characteristics and recharging tendency of aquifers. data revealed that a few samples have shown light yellow to brown color, which suggest presence of organic matter or metals such as iron in those groundwater samples. the color of water is also dependent on the degree of oxidation i.e. darker the color of groundwater, higher the degree of oxidation. all samples are saline to highly saline in taste which is due to high tds content (range: 805-40340 mean; 7820 ppm). saline taste of groundwater is reported from all depth ranges (12-300 feet) which suggest that salinity of groundwater in study area is free from depth variation. generally, it is observed that high tds is found in both shallow and deeper wells, but wells with more depth have relatively low tds content. it suggests that saline source is transmitting its salt content from shallow to deeper wells. water is not considered suitable for drinking if the quantity of dissolved minerals exceeds 1,000 mg/l [6].the groundwater temperature of collected samples ranges between 26-32˚c with a mean of 30˚c table 4, but most of the samples (n=15) have 30˚c or above suggesting that water is infiltrating from surface runoffs. asian review of environmental and earth sciences, 2020, 7(1): 9-17 12 © 2020 by the authors; licensee asian online journal publishing group the ph of groundwater in study area varies from 6.55 to 7.75 with a mean of 7.03 table 4. the suitable ph for drinking water ranges between 6.5–8.5 [6]. about half of the collected samples are acidic making these water wells unfit for drinking due to possible chemical reactivity. though ph has no direct effect on human health, its higher range accelerates the scale formations in water heating apparatus [7]. on the other hand it indirectly affects water quality and its parameters such as metal ion solubility and pathogen existence [8]. tds content of the collected samples ranges between 800-40340 ppm with a mean value of 7820 ppm table 4. all the samples have tds above desirable limit of who (500 ppm) for drinking purpose. tds content from natural sources vary from less than 30 mg/liter to as much as 6000 mg/liter [9] depending on the relative solubility of minerals in different geological regions. high tds content in groundwater of study area may rise due to the influx of natural saline water such as sea water intrusion [10] which is consistent with the fact that study area lies in the proximity of karachi coast where malir river channel is invaded by sea water. table-1. summary of physical parameters determined in collected groundwater samples of study area. physical parameters sample no well age well depth (ft) color taste temperature (ċ) hardness mg/l ph eh (mv) tds (ppm) ec (µs/ cm) latitude longi tude q1 1 year 250 colorless saline 32 600 6.91 76 3000 6000 24°52'16. 19"n 67° 5'31.2 1"e q2 15 years 22 light yellow saline 32 1200 7.21 57 4210 8420 24°51'43. 69"n 67° 5'30.0 6"e q3 3 years 130 colorless saline 29 1500 6.79 38 2100 4200 24°51'39. 21"n 67° 4'53.1 9"e q4 25 years 40 colorless saline 30 800 6.9 97 3100 6200 24°51'13. 67"n 67° 5'7.19 "e q5 20 years 12 colorless saline 30 900 7.42 16 805 1610 24°50'44. 04"n 67° 5'7.44 "e q6 3 years 20 light yellow saline 31 1100 7.37 40 4100 8200 24°50'47. 40"n 67° 4'39.2 9"e q7 3 years 35 colorless saline 30 3000 6.88 51 7830 1560 24°49'30. 80"n 67° 4'59.3 2"e q8 dna dna light yellow saline 30 400 7.75 -70 1100 2300 24°49'16. 89"n 67° 5'5.03 "e q9 3 years 180 light brown saline 26 920 7.37 -120 4000 8000 24°50'4.5 8"n 67° 4'48.8 0"e q10 dna dna light yellow saline 26 620 6.8 125 1020 2040 24°50'26. 05"n 67° 4'20.9 6"e q11 6 months 150 colorless saline 30.1 10000 6.57 -126 30200 6040 0 24°50'39. 01"n 67° 6'1.96 "e q12 9 years dna light yellow saline 30.5 900 7.3 -65 7230 1446 0 24°50'50. 24"n 67° 6'15.2 3"e q13 3 years 30 colorless saline 30 10000 6.63 -180 40340 8068 0 24°49'43. 45"n 67° 6'17.5 5"e q14 5 years 16 colorless saline 29.4 1000 7.1 -15 3600 7200 24°49'30. 63"n 67° 6'26.5 0"e q15 15 days 15 colorless saline 31.3 1300 6.98 16 5310 1062 0 24°49'15. 68"n 67° 6'17.6 2"e q16 2 years 25 colorless saline 30.1 1400 7.18 -101 1020 2040 24°48'51. 63"n 67° 6'25.3 0"e q17 7 years 100 colorless saline 31.1 500 6.55 86 20340 4068 0 24°50'21. 78"n 67° 6'22.5 0"e q18 2 months dna smoky saline 30 6000 6.83 33 11010 2202 0 24°51'0.5 0"n 67° 6'35.4 6"e q19 6 months 117 colorless saline 30.8 3000 7.23 38 2900 5800 24°51'20. 87"n 67° 6'48.7 2"e q20 7 months 300 colorless saline 28 700 7.02 98 3180 6360 24°51'27. 43"n 67° 7'29.3 2"e who limits 500 6.58.5 500 dna=data not available asian review of environmental and earth sciences, 2020, 7(1): 9-17 13 © 2020 by the authors; licensee asian online journal publishing group elevated content of tds produces gastro-intestinal irritation in human body [11]. according to prakash and soma [12] classification only 5% of the total samples (n=20) are found non-saline, 30% are slightly saline, 45% are moderately saline and 20% are very saline table 2 the variation in tds of collected groundwater samples is quite higher (800-40340 ppm), which is mainly attributed to anthropogenic activities and to geochemical process [13] prevailing in the study area. the hardness of groundwater samples ranges between 400-10000 mg/l with a mean of 2292 mg/l table 4. about 95% samples have hardness above permissible limit (500 mg/l) prescribed by world health organization (who) [6] for drinking purpose. the oxidation reduction potential of collected samples varies from -180 to +125 mv with a mean of +4.7 mv where about 65% samples showed positive eh suggesting the recent recharge. table 2. tds classification of study area groundwater (after prakash and soma [12]). classification tds in mg/l no. of samples non – saline < 1000 1 slightly saline 1000 – 3000 6 moderately saline 3000 – 10000 9 very saline > 10000 4 source: prakash and soma [12]. 3.2. chemical characteristics chemical parameters include major cations (na, k, ca, mg), anions (cl, no₃, so₄, hco₃) and minor/trace elements (fe, as) have been summarized in table 3. 3.2.1. major cations sodium is the major cation which has highly variable concentration (range: 205-14810 mg/l; mean 2587 mg/l). all samples have sodium concentration above permissible limit (200 mg/l) prescribed by who [14] for drinking purpose table 3. high level of sodium in collected samples is due to the involvement of seawater as the study area lies in the proximity (8 km approximately) of arabian sea. similar is true about potassium content (range 24-160 mg/l; mean: 90.7 mg/l). it is observed that all the collected samples are exceeding the safe limit of potassium (12 mg/l) table 3. main reason of increasing potassium in groundwater seems due to agricultural activities [15] and the sewage mixing. moreover, k might have come from the weathering of feldspar and clay minerals from the aquifer matrix as feldspars are more susceptible to weathering and alteration than quartz in silicate rocks [16].calcium and magnesium contents range between 75-800 and 48.6-2217 mg/l respectively. the mean value of calcium (231 mg/l) is double of the permissible limit by who 100 mg/l table 3. likewise, the mean concentration of mg is thrice the prescribed limit (150 mg/l). all samples have mg concentration above the who limit for drinking purpose except four samples (q3, q5, q12, and q15). about 70% of the total samples show relatively high mg concentration than ca. generally ca dominates over mg in groundwater but reverse occurs due groundwater interaction with dolomitic rocks [17] seawater intrusion or the cation exchange on clay surfaces. table-3. summary of chemical parameters determined in collected groundwater samples of study area. chemical parameters major cations major anions minor/trace elements sample no na k ca mg cl no3 so4 hco3 fe as q1 900 24 120 72.9 1100 8.03 230 290 8 bdl q2 1300 83 150 200.48 1700 13.8 980 200 bdl 5 q3 560 35 350 151.88 460 4.01 660 380 4 bdl q4 1070 106 230 54.68 180 18.88 320 300 bdl bdl q5 205 71 100 157.95 1600 4.6 106 490 bdl 5 q6 1450 131 120 194.4 600 10 250 260 25 bdl q7 4500 125 90 674.32 190 9.06 650 224 35 5 q8 220 79 80 48.6 200 12.9 190 220 102 bdl q9 1200 106 200 102.06 2100 8.48 120 550 4950 25 q10 260 64 80 102.06 604 4.19 66 335 776 5 q11 14810 144 350 2217.38 2000 8.66 2050 700 65 5 q12 2830 100 100 157.95 3019 7.6 740 210 208 5 q13 980 160 800 1944 30600 16 500 370 315 5 q14 1170 82 150 151.87 1700 9.28 310 340 7 5 q15 2616 96 160 218.7 1900 11.67 360 360 5 5 q16 380 69 190 224.78 260 3.37 680 270 65 100 q17 8620 142 600 85.05 12700 8.42 495 380 bdl 5 q18 5850 109 400 1215 5600 16.78 210 390 194 5 q19 1300 50 276 561.33 980 25.21 2010 280 4 bdl q20 1520 38 75 124.53 200 27.69 680 310 6 bdl who limit 200 12 75 150 250 10 250 300 300 10 all values are in (mg/l), except fe & as which are in (µg/l) bdl=below detection level 3.2.2. major anions the concentration of chloride (range 180-30600 mg/l; mean: 3384.5 mg/l) and sulphate (range: 662050 mg/l; mean: 580.35 mg/l) are highly variable. about 80% of the total collected samples have chloride concentration above who standard (250 mg/l) for drinking water. strong positive correlation of cl with ca (r² = 0.955) followed by tds and ec (r² = 0.786) suggest that the evaporative concentration of major salts is increasing asian review of environmental and earth sciences, 2020, 7(1): 9-17 14 © 2020 by the authors; licensee asian online journal publishing group in the study area due to aridity and sewage infiltration. moreover, high concentrations of clmay be due to the effect of sea tides in the qayyumabad area as suggested by mashiatullah, et al. [18]. lusczynski and swarzenski [19] considers chloride content above 50 mg/l as an indication of salt water intrusion, the groundwater of study area contains chloride concentration far above the limits suggested by lusczynski and swarzenski [19] confirming the salt water intrusion. similarly, mean concentration of sulphate is twice the permissible limit (250 mg/l) of who for drinking water table 4. very high sulphate content in the groundwater of study area suggests the gypsum dissolution, use of inorganic fertilizer and the recent recharge of saline water [20, 21]. high concentration of sulphate in study area is consistent with the study of mashiatullah, et al. [18] in ghizri creek which is 5.6 km away from qayyumabad. it is also complimenting the seawater intrusion mechanism as an agent of high sulphate and chloride contents in groundwater of study area. nitrate concentration ranges between 3.37-27.69 mg/l with a mean of 11.43 mg/l table 4. about 50% of total collected samples are unfit for drinking in terms of nitrate content as against who compliance (10 mg/l). it indicates that nitrate reducing bacteria are active in the groundwater of the study area, which is supported by exceptionally high bicarbonate content (mean: 346.9 mg/l) suggesting that organic matter decomposition is followed by nitrate reduction in the groundwater [22]. bicarbonate content in collected groundwater samples ranges between 200-700 mg/l with a mean of 342.95 mg/l. about 55% of total collected samples have bicarbonate content above permissible limit (300 mg/l). bicarbonate may be released from the dissolution of carbonate minerals via biodegradation of organic matter [23-25]. 3.2.3. minor and trace elements iron concentration in collected groundwater samples ranges between 4-4950 µg/l with a mean of 423 µg/l table 4. it is observed that, all samples have iron concentration within permissible limit (300 µg/l) set by who except three samples (q9, q10 and q13) which have high iron concentration (4950, 776 and 315 µg/l respectively). iron in these samples may have come from some additional sources or due to prevalence of reducing conditions. sample 9 contains rise value of both fe and as but vice versa of this happens in sample 16 where extremely high value of arsenic as is present regardless of iron fe. about 95% of the total samples (n=20) have very low correlation between fe and as. it supports the notion that reduction of iron oxyhydroxide is necessary but not a sufficient condition for elevated arsenic concentration in groundwater of holocene aquifers [26]. arsenic content in collected samples varied between 5-100 µg/l with a mean of 13.84 µg/l table 4. only two samples (9 and 16) showed the abnormally high concentration of as i.e. 25 and 100 µg/l respectively, arsenic is naturally occurring element available in the soil and sediments [27-29]. however arsenic can be introduced to a groundwater system through various means, including surface water and precipitation as well as anthropogenic and naturally occurring sources [30, 31]. there is a relationship between the degree of reduction of the groundwater and the arsenic concentration; the more groundwater reduction, the more will be the arsenic concentration [32]. since the groundwater of study area is mostly oxic as indicated by positive eh values for most of the samples, the occurrence of low arsenic content is consistent with the redox rule. table-4. statistics of physicochemical parameters. parameters minimum maximum mean std deviation hardness 400 10000 2292 2930.099 well depth(ft) 12 300 90.12 90.88 temperature (c) 76 37 79.86 1.619 ph 6.55 7.75 7.05 0.314 eh (mv) -180 +125 +4.7 +86.309 tds (ppm) 805 40340 7819.8 105.18 ec 1610 80680 14939.5 21267.8 na 205 14810 2587 3.58e+07 k 24 160 90.7 38.267 ca 75 800 231.05 190.349 mg 48.6 2217.38 432.99 629.069 cl 180 30190 3384.65 7.01e+03 no3 3.37 27.69 11.43 6.689 so4 66 2050 580.35 554.697 hco3 200 700 342.9 122.969 fe 4 4950 423 1.22e+03 as 5 100 13.84 26.46 3.3. ionic interrelationship strong positive correlation of well depth with bicarbonate (r = 0.851) and iron (r = 0.731) suggest that reducing conditions are increasing with depth table 5. it is well established that bicarbonate may be released from dissolution of carbonate minerals via biodegradation of organic matter [23-25]. there is very weak negative relation of na with cl (r=-0.212) table 5 but this can be increases with time. the na/cl relation has often been used to identify the mechanism for salinity distribution and saline intrusion [33-35]. if na and cl ions enter in solution in equal quantity during the dissolution of halite, a linear relationship may be observed between these ions [36]. this relation is observed in our sample 17 and 18 table 3. abnormally high value of chloride concentration in sample q13 (30600 mg/l) is observed regardless of sodium concentration. this concentration pattern suggests that sodium and chloride are not strongly correlated with each other. this pattern cannot rule out the same source of na and cl due to the fact that a part of na is adsorbed onto the clays through cation exchange mechanism while chloride still remains in the mobile phase due to its conservative behavior. strong positive correlation of na with so4, mg, and hco3 (r = 0.936) (r = 0.666) (r = 0.691) table 5suggest that seawater intrusion. the negative correlation between nitrate and arsenic (r = -0.747) table 5 suggest that there is inverse relation between these two. negative correlation between as and no3 does not exclude a common asian review of environmental and earth sciences, 2020, 7(1): 9-17 15 © 2020 by the authors; licensee asian online journal publishing group source. under anaerobic conditions no3 is a very conservative ion whereas as is highly immobile at best in a nearneutral ph range.there is a relationship between the degree of reduction of the groundwater and the arsenic concentration; the more groundwater reduction, the more will be the arsenic concentration [32]. high concentration of nitrate in some samples suggests that the conditions are sub-oxic to anoxic. the reducing nature of the groundwater has led to the reduction of some of the arsenic to as (iii) and possible desorption of arsenic since as (iii) is normally less strongly sorbed by the iron oxides than as(v) under near-neutral ph conditions of groundwater [27, 37]. further reduction will lead to the partial dissolution of the poorly crystallized ferric oxide with subsequent release of iron and additional arsenic [38]. table-5. correlation matrix of physicochemical parameters determined in collected groundwater samples of study area. correlation matrix well depth hard ness temp eratu re ph eh tds ec na k ca mg cl no3 so4 hco 3 fe a s well depth 1 hardness 0.206 1 temperat ure -0.707 0.257 1 ph 0.093 -0.898 -0.593 1 eh -0.45 -0.595 0.324 0.206 1 tds 0.147 0.975 0.211 -0.857 -0.624 1 ec 0.147 0.975 0.211 -0.857 -0.625 1 1 na 0.487 0.595 0.211 -0.634 -0.088 0.436 0.436 1 k 0.286 0.879 0.058 -0.798 -0.407 0.902 0.902 0.481 1 ca 0.002 0.802 0.095 -0.606 -0.758 0.897 0.897 0.023 0.722 1 mg 0.232 0.995 0.274 -0.913 -0.546 0.952 0.951 0.666 0.872 0.74 1 cl -0.18 0.646 0.094 -0.5 -0.598 0.786 0.786 -0.212 0.657 0.955 0.571 1 no3 -0.161 0.505 0.167 -0.536 -0.157 0.661 0.661 -0.054 0.693 0.685 0.457 0.78 1 so4 0.349 0.674 0.334 -0.683 -0.245 0.5 0.5 0.936 0.429 0.148 0.735 -0.11 -0.161 1 hco3 0.851 0.468 -0.356 -0.239 -0.528 0.408 0.409 0.691 0.394 0.21 0.493 -0.029 0.053 0.582 1 fe 0.731 -0.278 -0.942 0.599 -0.312 -0.215 -0.215 -0.222 -0.037 -0.084 -0.3 -0.081 -0.083 -0.378 0.394 1 as -0.097 -0.339 -0.055 0.475 -0.231 -0.406 -0.406 -0.333 -0.594 -0.189 -0.351 -0.242 -0.747 -0.071 -0.27 0.04 1 this matrix is not positive definite 3.4. principal component analysis (pca) to accurately identify the main processes governing the hydrochemistry of groundwater in the system, a factor analysis was performed using a subset of variables including the physical parameter (well depth, temperature, hardness, ph, eh, total dissolved solids, electrical conductivity) while chemical parameters (sodium, potassium, calcium, magnesium, chloride, nitrate, sulphate, bicarbonate), and minor/trace elements (iron, arsenic). four factors where extracted which have eigen values greater than 1 and these factors are discussed separately in detail. the pca was performed on 20 groundwater samples where four principal components were extracted. the first four principal components together account for about 97.62% of the total variance in the data set, in which the first principal component explains 50.94% of the total data set variance, the second component explained the 20.43% while third component explained 16.89% and the fourth component explains the 9.37% table 6. table-6. principal components analysis (pca). principle component matrixa component f1 f2 f3 f4 tds 0.99 -0.031 -0.121 0.062 ec 0.99 -0.03 -0.121 0.062 hardness 0.986 0.017 0.082 0.124 mg 0.975 0.034 0.172 0.099 k 0.914 0.069 -0.106 -0.247 ph -0.896 0.319 -0.297 0.061 ca 0.829 -0.087 -0.489 0.248 cl 0.698 -0.249 -0.659 0.131 no₃ 0.632 -0.301 -0.498 -0.481 eh -0.566 -0.461 0.373 -0.553 well depth 0.197 0.965 0.093 -0.111 fe -0.238 0.818 -0.474 -0.165 temperature 0.241 -0.816 0.441 0.113 hco₃ 0.476 0.768 0.239 -0.1 na 0.552 0.301 0.765 -0.14 so₄ 0.591 0.191 0.759 0.194 as -0.459 0.076 0.023 0.871 eigen values 8.66 3.474 2.871 1.592 variance % 50.939 20.435 16.888 9.365 cumulative 50.939 71.374 88.262 97.626 extraction method: principal component analysis. asian review of environmental and earth sciences, 2020, 7(1): 9-17 16 © 2020 by the authors; licensee asian online journal publishing group 3.4.1. factor 1 (f1) f1 accounts for 50.94% of the total variance and strongly positive loaded with tds (0.99), ec (0.99), hardness (0.98), magnesium (0.97), potassium (0.91), calcium (0.83), chloride (0.7), nitrate (0.63), sodium (0.55) and sulphate (0.59) while strong negatively loaded with ph (-0.89) and eh (-0.56) table 6. this clustering of variables associated with f1 suggest that the conditions are reducing with acidic ph which is leading to dissolve higher amount of salts and minerals in the groundwater of the area. comparing the role of ph and eh, it is observed that ph has dominating role in mineral dissolution and leaching of ions from their corresponding salts. about 50% of total samples have ph value less than 7 which are considered acidic table 1. 3.4.2. factor 2 (f2) f2 accounts for 20.43% of total variance and strongly positive loaded with well depth (0.96), iron fe (0.82) and bicarbonate hco₃ (0.77) while negatively loaded with temperature (-0.82) table 6. this clustering of variables associated with f2 suggests that fe and hco₃ are increases with increasing depth. due to the reducing condition leading to increase in concentration of hco₃ and fe in groundwater of study area. the correlation of concentration of bicarbonate and iron is(r = 0.4) table 5 though the relationship between these two is not very significant because decomposition of oxygen by bacteria is not reach the stage of iron but as far as the bacterial activity present in the groundwater relationship between these two becomes stronger and stronger. 3.4.3. factor 3 (f3) f3 accounts for 16.88% of total variance which shows strong positive loading with sodium (0.76), sulphate (0.76) while negative with chloride (-0.66) table 6. this cluster pattern of variables suggests that ion exchange of sodium is happening in groundwater of study area. generally the source of sodium and chloride is same, but sodium has a tendency to ion exchange, so when the saline source transmit its concentration towards the depth sodium replace itself with available cation while the chloride concentration were kept constant because it is conservative and thereby reported in groundwater samples regardless of na. 3.4.4. factor 4 (f4) f4 accounts for 9.36% of the total variance and showing strong positive loading with arsenic as (0.87) while negatively loaded with nitrate no3 (-0.48) and eh (-0.55) table 6. this cluster of variable loadings clearly shows that the nitrate reducing bacteria are responsible for arsenic dissolution as arsenic is mobilized in reducing conditions [39]. under anoxic conditions, nitrate reducing bacteria use nitrate instead of oxygen to oxidize organic material. this process of denitrification results in decrease of nitrate concentration in groundwater [40]. reducing condition is very important for arsenic mobilization [39], but in present study the weak correlation of orp with the arsenic indicates that there is recent inflow of nitrate in the system. on the other hand the principal component analysis has shown the factor 4 as important one which caters the major role of reducing conditions, nitrate and arsenic. 4. conclusion the groundwater of study area is physically, chemically and biologically contaminated. both natural process and anthropogenic activities are responsible for polluting the groundwater. high salinity, hardness and bacterial contamination are major water quality deteriorating factors. most of the physiochemical parameters are against who compliance. the main parameters deteriorating the quality of groundwater are tds, na, k, ca, mg, cl, no₃, so₄ and hco₃. water rock interaction is prime driver in study area which is leading to salt leaching followed by anoxia prevalence due to sewage mixing. reducing environment is responsible for leaching of as from river bed sediments and alluvium forming the similar to aquifers in other river basins of the world. seawater intrusion is also evident in the groundwater of study area. it is concluded that groundwater of qayyumabad is unfit for drinking purpose and its long term intake may cause serious health consequences. references [1] a. hamzah, m. p. abdullah, s. sarmani, and m. a. johari, "chemical and bacteriological monitoring of drinking water from an urbanised water catchment drainage basin," environmental monitoring and assessment, vol. 44, pp. 327-338, 1997. [2] m. kumar, a. ramanathan, m. s. rao, and b. kumar, "identification and evaluation of hydrogeochemical processes in the groundwater environment of delhi, india," environmental geology, vol. 50, pp. 1025-1039, 2006.available at: https://doi.org/10.1007/s00254-006-0275-4. [3] k. r. karanth, groundwater assessment development and management. new delhi: tata mcgraw-hill publication company. ltd, 1989. [4] s. monawwar, "study of heavy metals pollution level and impact on the fauna and flora of the karachi and gawadar coast," a report submitted to national institute of oceanography, pakistan2002. [5] m. a. farooq, n. yasmin, and s. mughal, "human induced impact on malir river basin karachi, pakistan," world applied sciences journal, vol. 9, pp. 1450-1456, 2010. [6] world health organization (who), guidelines for drinking-water quality, 4th ed. geneva: world health organization, 2011. [7] a. narsimha, n. anitha, v. sudarshan, and manjulatha, "evaluation of groundwater quality and its suitability for drinking purposes in gunthakal area, ananthapur district, andhra pradesh, india," advances in applied science research, vol. 4, pp. 70-76, 2013. [8] m. mohamadi, g. mohamadi, m. ney, and k. ebrahimi, "temporal and spatial variation of groundwater quality in qazvin," journal of iran water research, vol. 5, pp. 41-52, 2011. [9] who/unep, global freshwater quality. oxford: alden press, 1989. [10] c. d. langevin and m. zygnerski, "effect of sea-level rise on salt water intrusion near a coastal well field in southeastern florida," groundwater, vol. 51, pp. 781-803, 2013.available at: https://doi.org/10.1111/j.1745-6584.2012.01008.x. [11] m. saleem, a. hussain, and g. mahmood, "analysis of groundwater quality using water quality index: a case study of greater noida (region), uttar pradesh (up), india," cogent engineering, vol. 3, p. 1237927, 2016.available at: https://doi.org/10.1080/23311916.2016.1237927. [12] k. l. prakash and s. soma, r. k., groundwater quality assessment on anekal taluk. india: bangalore urban district, 2006. [13] m. jeevanandam, r. nagarajan, m. manikandam, m. senthilkumar, s. srinivasalu, and m. v. prasanna, hydrogeochemistry and microbial contamination of groundwater from lower ponnaiyar basin. cuddalore district, 2012. asian review of environmental and earth sciences, 2020, 7(1): 9-17 17 © 2020 by the authors; licensee asian online journal publishing group [14] who, guidelines for drinking-water quality, 4th ed. geneva: world health organization, 2011. [15] j. sayyed and a. bhosle, "analysis of chloride, sodium and potassium in groundwater samples of nanded city in mahabharata, india," european journal of experimental biology, vol. 1, pp. 74-82, 2011. [16] s. kenneth, okiongbo, and e. akpofure, "identification of hydrogeochemical processes in groundwater using major ion chemistry: a case study of yenagoa and environs, southern nigeria," global journal of geological sciences, vol. 12, pp. 39-52, 2014.available at: https://doi.org/10.4314/gjgs.v12i1.5. [17] c. sarala and b. p. ravi, "assessment of groundwater quality parameters in and around jawaharnagar, hyderabad," international journal of scientific and research publications, vol. 2, pp. 2250-3153, 2012. [18] a. mashiatullah, r. qureshi, e. ahmad, m. tasneem, m. sajjad, and h. khan, "groundwater salinity in coastal aquifer of karachi, pakistan," science vision, vol. 7, pp. 195-209, 2002. [19] n. lusczynski and w. swarzenski, salt water encroachment in southern nassau and se queens countries, long island. new york: u.s geological survey professional paper 1613-f, 1996. [20] k. p. nguyen and r. itoi, "source and release mechanism of arsenic in aquifers of the mekong delta, vietnam," journal of contaminant hydrology, vol. 103, pp. 58-69, 2009.available at: https://doi.org/10.1016/j.jconhyd.2008.09.005. [21] h. m. anawar, s. m. tareq, and g. ahmed, "is organic matter a source or redox driver or both for arsenic release in groundwater?," physics and chemistry of the earth, parts a/b/c, vol. 58, pp. 49-56, 2013.available at: https://doi.org/10.1016/j.pce.2013.04.009. [22] s. n. davis and r. j. m. de wiest, hydrogeology. john wiley and sons: new york, 1996. [23] c. h. jeong, "effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area, korea," journal of hydrology, vol. 253, pp. 194-210, 2001.available at: https://doi.org/10.1016/s0022-1694(01)00481-4. [24] a. shamsudduha, j. a. uddin, m. saunders, and k. lee, "quaternary stratigraphy, sediment characteristics and geochemistry of arsenic-contaminated alluvial aquifers in the ganges–brahmaputra floodplain in central bangladesh," journal of contaminant hydrology, vol. 99, pp. 112-136, 2008.available at: https://doi.org/10.1016/j.jconhyd.2008.03.010. [25] c. petalas and k. anagnostopoulos, "application of stepwise discriminant analysis for the identification of salinity sources of groundwater," water resources management, vol. 20, pp. 681-700, 2006.available at: https://doi.org/10.1007/s11269-005-9002-2. [26] a. van geen, t. protus, z. cheng, a. horneman, a. seddique, m. hoque, and k. ahmed, "testing groundwater for arsenic in bangladesh before installing a well," environmental science & technology, vol. 38, pp. 6783-6789, 2004.available at: https://doi.org/10.1021/es049323b. [27] p. l. smedley and d. g. kinniburgh, "a review of the source, behaviour and distribution of arsenic in natural waters," applied geochemistry, vol. 17, pp. 517-568, 2002.available at: https://doi.org/10.1016/s0883-2927(02)00018-5. [28] k. g. stollenwerk, geochemical processes controlling transport of arsenic in groundwater: a review of adsorption. in arsenic in ground water. boston, ma: springer, 2003. [29] n. e. korte and q. fernando, "a review of arsenic (iii) in groundwater," critical reviews in environmental science and technology, vol. 21, pp. 1-39, 1991. [30] m. urik, p. littera, and m. kolen, "removal of arsenic (v) from aqueous solutions using chemically modified sawdust of spruce (picea abies): kinetics and isotherm studies," international journal of environmental science & technology, vol. 6, pp. 451-456, 2009.available at: https://doi.org/10.1007/bf03326084. [31] r. reza and g. singh, "heavy metal contamination and its indexing approach for river water," international journal of environmental science & technology, vol. 7, pp. 785-792, 2010.available at: https://doi.org/10.1007/bf03326187. [32] v. m. brömssen, m. jakariya, p. bhattacharya, k. m. ahmed, m. a. hasan, o. sracek, l. jonsson, l. lundell, and g. jacks, "targeting low-arsenic aquifers in matlab upazila, southeastern bangladesh," science of the total environment, vol. 379, pp. 121132, 2007.available at: https://doi.org/10.1016/j.scitotenv.2006.06.028. [33] h. o. nwankwoala and g. j. udom, "investigation of hydrogeochemical characteristics of groundwater in port harcourt city, nigeria: implications for use and vulnerability," journal of applied science and environmental management, vol. 15, pp. 479-488, 2011. [34] b. panteleit, w. kessels, w. kantor, and h. d. schulz, "geochemical characteristics of salinization-zones in the coastal aquifer test field (cat-field) in north-germany," presented at the first international conference on saltwater intrusion and coastal aquifers monitoring, modeling, and management, essaouira, morocco, 2001. [35] k. sami, "recharge mechanisms and geochemical processes in a semi-arid sedimentary basin, eastern cape, south africa," journal of hydrology, vol. 139, pp. 27-48, 1992.available at: https://doi.org/10.1016/0022-1694(92)90193-y. [36] j. d. hem, study and interpretation of chemical characteristics of natural water, 3rd ed.: u.s geological survey water-supply paper 2254 1986. [37] m. f. hossain, "arsenic contamination in bangladesh—an overview," agriculture, ecosystems & environment, vol. 113, pp. 1-16, 2006.available at: https://doi.org/10.1016/j.agee.2005.08.034. [38] p. bhattacharya, d. chatterjee, and g. jacks, "occurrence of arsenic-contaminatedgroundwater in alluvial aquifers from delta plains, eastern india: options for safe drinking water supply," international journal of water resources development, vol. 13, pp. 7992, 1997.available at: https://doi.org/10.1080/07900629749944. [39] w. robertson, j. cherry, and s. schiff, "atmospheric sulfur deposition 1950–1985 inferred from sulfate in groundwater," water resources research, vol. 25, pp. 1111-1123, 1989.available at: https://doi.org/10.1029/wr025i006p01111. [40] l. w. canter and r. c. knox, groundwater pollution control. boca raton, fl: lewis publishers, 1985. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 61 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 61-66, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.61.66 © 2020 by the authors; licensee asian online journal publishing group spatio-temporal analysis of urban built-up land in the hanoi metropolitan area (vietnam) using remotely sensed images thanh tien nguyen faculty of surveying, mapping and geographic information, hanoi university of natural resources and environment, hanoi, vietnam. abstract rapid and unplanned urbanization leads to temperature rise, urban vegetation decrease, and builtup land increase, forming an urban heat island. it is, therefore, the change of built-up land plays an important role in surface urban heat island studies. this study aims to analyze spatio-temporal changes of urban built-up land in the hanoi metropolitan area (hma), vietnam, using landsat remotely sensed images acquired in 1996 and 2016. landsat time-series images were first preprocessed preprocessed to account for sensor, solar, atmospheric, and topographic effects. urban built-up land was then extracted based on an ndbi based continuous built-up index (buc). spatiotemporal changes of built-up land were finally analyzed by means of geographic information system (gis). it was found that the urban built-up land area had increased from 4063.1 hectares in 1996 to 7163.2 hectares in 2016 which account for 13.3% and 23.4% of the total area, respectively. the built-up land area had increased by about 10.1% of the total area in 20 years. on average, 0.5% of the urban built-up area increases each year. the urban built-up land tends to expand to the west, southwest, and south of the hma. these findings demonstrate the effectiveness of the proposed method for spatio-temporal analysis of built-up land in urban areas using remotely sensed images. keywords: spatio-temporal analysis, change detection, urban built-up land, remotely sensed data, landsat time-series images, urban heat islands; hanoi metropolitan area (vietnam). citation | thanh tien nguyen (2020). spatio-temporal analysis of urban built-up land in the hanoi metropolitan area (vietnam) using remotely sensed images. asian review of environmental and earth sciences, 7(1): 61-66. history: received: 17 february 2020 revised: 20 march 2020 accepted: 22 april 2020 published: 25 may 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. competing interests: the author declares that there are no conflicts of interests regarding the publication of this paper. transparency: the author confirms that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 62 2. study area and data used ............................................................................................................................................................. 62 3. methodology ..................................................................................................................................................................................... 63 4. results and discussion.................................................................................................................................................................... 63 5. conclusions ........................................................................................................................................................................................ 65 references .............................................................................................................................................................................................. 66 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.61.66&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1662 https://orcid.org/0000-0002-7600-5858 https://www.asianonlinejournals.com/index.php/arees/article/view/1662 https://orcid.org/0000-0002-7600-5858 https://www.asianonlinejournals.com/index.php/arees/article/view/1662 https://orcid.org/0000-0002-7600-5858 asian review of environmental and earth sciences, 2020, 7(1): 61-66 62 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study provides the scientific basis for the spatio-temporal analysis of urban built-up land in urban areas through landsat time-series images. in addition, this research can contribute a baseline for further empirical researches in the area of urban heat island studies in the hanoi metropolitan area, vietnam. 1. introduction land covers in urban areas tend to change more drastically over a short period of time than elsewhere because of incessant urbanization [1]. rapid development in urban areas has brought land cover change, especially built-up land urban in areas in such a developing country as vietnam. the replacement of vegetation cover with urban builtup land caused by urbanization has led to negative environmental repercussions to urban areas [2], such as reduced precipitation [3, 4] more dryness [2] and warmer temperatures [5] which contribute greatly to atmospheric and urban heat islands. built-up land in urban areas has been considered as an effective indicator of urban development and environmental quality. recent studies have also shown that the increase of built-up land has resulted in serious negative effects on humans and environments such as the weakening of living environments and an increased mortality rate [6] the adverse health effects [7] and the worsening local weather and climate [8]. it is, therefore, the spatio-temporal analysis of urban built-up land change plays an important role in urban environmental studies. traditionally, manual interpretation of aerial photography or field surveys have been commonly used for built-up land change detection [9, 10]. the main advantage of these conventional methods is that built-up land could be captured with a high accuracy [11] but they were nearly impossible to gather enough data over a large area [12, 13] especially for such big urban areas as megacities. the occurrences of remote sensing technology now have overcome most of these limitations of conventional methods. digital remotely sensed images allow for mapping urban areas and detecting land-use change in a more timely, cheaper and more accurate manner, especially when using the most recent high-resolution satellite imagery [11]. since remotely sensed imagery of high-resolution satellite sensors such as landsat-1, 2, 3 mss, -5 tm, -7 etm+ and -8 oli started to become available, built-up land change detection and monitoring from space became easier. a commonly used approach for the definition of built-up land areas is conventional multi-spectral classification [2]. however, due to spectral confusion of the heterogeneous builtup land class, xu [2] concluded that this method may not produce satisfactory accuracy. therefore, many indices were proposed to discriminate built-up land from non-built-up land in urban areas such as the normalised difference vegetation index (ndvi) [14] normalised difference built-up index (ndbi) [1], index-based built-up index (ibi) [2], urban index (ui) [15], enhanced built-up and bareness index (ebbi) [16], vegetation index built-up index (vibi) [17], a ndbi based continuous built-up index (buc) [18], and most recently, dry built-up index (dbi) [19]. the reviewed literature on spectral indices leads [19] to conclude that these indices have not entirely successfully addressed the confusion between impervious surfaces and bare soil. commonly used ndbi and ui indices are unable to verify the distribution of built-up versus bare land areas as-syakur, et al. [16]. he, et al. [18] indicated that buc is considered the most effective index for mapping built-up land. hence, by employing the buc, this study focusses on detecting the spatio-temporal change of urban built-up land in the hanoi metropolitan area (vietnam). 2. study area and data used figure-1. study area of the hma: 6-5-4 false color composite of landsat-8 oli images. the hma is located in the center of hanoi capital of vietnam. its geographic location extends latitudinally from 20°54'34.14" to 21°6'22.69", and longitudinally from 105°42'16.97" to 105°56'21.48" figure 1 covering an area of about 274 km2. hanoi, one of the largest cities in vietnam with an estimated population of 8.05 million and a population density of 2,300 people for every square kilometer in 2019, undergoes a rapid urbanization, especially after the doi moi policy in 1986. rapid urbanization has caused vegetation to be replaced by built-up land dramatically [20]. landsat-5 and 8 time-series images (path 127, row 045/046) with 30-m spatial resolution of asian review of environmental and earth sciences, 2020, 7(1): 61-66 63 © 2020 by the authors; licensee asian online journal publishing group distributed by the u.s. geological survey were used in this study. these images were acquired on 10 june 1996 and on 16 may 2016. the quality of all landsat images was rather good (9/9) with no cloud cover over in the hma. landsat image processing was carried out in the environment for visualizing images software: envi version 5.2. maps were produced by arcgis 10.2 software [21]. 3. methodology 3.1. remotely sensed image pre-processing the pre-processing of landsat images includes two main steps. the conversion of the digital number data ( ) to top of atmosphere (toa or at-sensor) radiance ( ) is first performed using calibration parameters provided in the metadata file. the -to conversion for landsat-5 tm image and landsat-8 oli image [22] are conducted by means of equations 1 and 2 respectively: ( ) (1) where is at-sensor spectral radiance [w/ ] at the wavelength (µm); is digital number values; and are minimum and maximum digital number corresponding to , respectively; and are at-sensor spectral radiance [w/ ]. (2) where is at-sensor spectral radiance [w/(m2·sr·µm)] at the wavelength (µm); and are the radiance multiplicative scaling factor and the radiance additive scaling factor for the bands, respectively; and is the digital number. after the -to conversion, atmospheric effects for landsat-5 and 8 reflective bands is then carried out using flaash algorithm proposed by adler-golden, et al. [23]. the spectral radiance of landsat bands in flaash model is identified based on the equation 3 [23]:          s a e  1           s b e e   1 (3) where  is the surface reflectance of a pixel; e is the average surface reflectance for the pixel and surrounding pixels; s is the spherical albedo of the atmosphere; is the radiance back-scattered by the atmosphere; a and b are coefficients depending on atmospheric and geometric conditions. the values of a, b, s, and are obtained based on modtran4 model [24]. after the water retrieval, the spatially averaged reflectance e is identified using the following equation [23, 24]:           s ba e e   1 )( (4) where is spatially averaged reflectance; a, b, s and e are defined as in equation 3. 3.2. built-up land extration from landsat images the ndvi is considered as an indication of the presence of vegetation and amount or condition of vegetation on pixel basis [6, 25], whereas, the ndbi is an index for mapping built-up land [24]. in this study, the continuous built-up index (buc) proposed by he, et al. [18] which is based on ndvi and ndbi indices was employed to extract urban built-up land. these indices are estimated from landsat bands using equations 5, 6 and 7, respectively: (5) (6) (7) where , , and are the ground reflectance of landsat-5 tm band 3 of and landsat-8 oli band 4, of landsat-5 tm band 4 and landsat-8 oli band 5, and of landsat-5 tm band 5 and landsat-8 oli band 6, respectively. the buc is the resultant binary image with only the built-up and barren pixels having positive value, thus allowing built-up areas to be mapped automatically [1]. 3.3. spatio-temporal analysis of built-up land changes after urban built-up land is extracted from landsat-5 and -8 images at two-time points, the change of urban built-up land is detected with the help of gis by means of arcgis software. in which, arcgis software helps to determine the built-up area, the percentage and spatial distribution during the period in the study area. spatiotemporal changes of built-up land were finally analyzed and discussed by comparing with previous findings. 4. results and discussion 4.1. ndbi in 1996 and 2016 the ndbi distribution in the hma obtained from landsat-5 tm and -8 oli images acquired on 10 june 1996 and 16 may 2016 are shown in figure 2, whereas it’s statistics are summarized in table 1. data from table 1 illustrates that it’s minimum, mean and maximum values of the ndbi computed from 1996 landsat-5 tm image were -0.77, -0.07 and 0.56, respectively. whereas, the minimum, mean and maximum values of the ndbi retrieved from 2016 landsat-8 oli were -0.45, 0.02 and 0.58, respectively. it can be seen that the ndbi values of 2016 were larger than those of 1996. this shows that the built-up land has increased in the period 1996-2016. small areas of asian review of environmental and earth sciences, 2020, 7(1): 61-66 64 © 2020 by the authors; licensee asian online journal publishing group high ndbi values were detected in the core urban areas of the hma in 1996 figure 2, left. however, these areas of high ndbi values had greatly expanded towards the western, north-western and south-western parts of the core urban hma figure 2, right. the rapid expansion of high ndbi value areas during the period of 1996-2016 was due to the high rate of urbanization after the doi moi policy [26]. data from histograms in figure 3 demonstrates that the distribution of the ndbi in 1996 was left-skewed with a relatively high number of low ndbi values figure 3, left, however, this trend had changed in 2016. the ndbi in 2016 shows the number of pixels with ndbi values had increased much stronger than that of 1996. nguyen, et al. [20] reported that the ndbi had been increasing dramatically in the period of 1996-2007. it can be concluded from the above-discussion that ndbi values had been increased in the period of 1996-2016. table-1. descriptive statistics of the ndbi, buc in the hma. index date minimum mean maximum standard deviation ndbi 1996-6-10 -0.77 -0.07 0.56 0.02 2016-5-16 -0.45 0.02 0.58 0.17 buc 1996-6-10 -1.00 0.53 0.94 0.41 2016-5-16 1.00 0.58 1.00 0.40 figure-2. ndbi in the hma in 1996 (a) and 2016 (b). figure-3. histograms of ndbi in 1996 (a) and 2016 (b). 4.2. buc in 1996 and 2016 figure-4. built-up index in the hma in 1996 (a) and 2016 (b). asian review of environmental and earth sciences, 2020, 7(1): 61-66 65 © 2020 by the authors; licensee asian online journal publishing group figure-5. histograms of built-up index in 1996 (a) and 2016 (b). the distribution of the buc in the hma on 10 june 1996 and 16 may 2016 are shown in figures 4 and 5, whereas it’s statistics are summarized in table 1. data from figure 3 shows that similar to those of the ndbi, areas of low buc values were mainly detected in the western, north-western and south-western parts of the hma at the two-time points, whereas, areas of high buc values were mainly concentrated in the core urban areas of the hma. data from table 1 demonstrates buc ranged from -1 to 1 at the two-time points. the mean values of 0.53 in 1996 and 0.58 in 2016 proves built-up land had decreased during this period. data from histograms in figure 5 demonstrates that the distribution of the buc in 1996 was strongly right-skewed with many low buc values detected on the left of the histogram, especially for the negative buc values figure 5-a. however, this trend had changed in 2016. data in figure 5-b demonstrates that the number of pixels with values greater than zero had increased much more than that of 1996. it is apparent that the values of the built-up index had increased dramatically during the period from 1996 to 2016. 4.3. spatio-temporal changes of built-up land during 1996-2016 table-2. summary of built-up land in the hma during the period of 1996-2016. land cover 1996 2016 area (ha) percent (%) area (ha) percent (%) built-up 4063.1 13.3 7163.2 23.4 non-built-up 26566.6 86.7 23466.4 76.6 total 30629.6 100.0 30629.6 100.0 figure-6. built-up land in the hma in 1996 (a) and 2016 (b). the spatial distribution of urban built-up land in the hma is shown in figure 6, whereas, its statistics are summarized in table 2. data in table 2 shows that the total urban built-up land area was 4063.1 hectares; accounting for 13.3% of the total area is 1996, while the non-built-up land area was 26566.6 hectares, accounting for 86.7% of the total area. the distribution of urban built-up land was mainly concentrated in the central hma area figure 6-a. the built-up land area had increased to 7163.2 hectares in 2016 which accounts for 23.4% of the total area. data in figure 6-b shows that the built-up land tends to expand to the west, southwest, and south of the hma. thus, the urban built-up land area had increased to about 10% of the total area in 20 years. a total of 0.5% of the built-up area increases on average each year. this result shows that hma had experienced a fairly fast urbanization rate in the period of 1996-2016. 5. conclusions in this study, spatio-temporal analysis of built-up land changes in the hma, vietnam was investigated based on landsat time-series images acquired in 1996 and 2016. landsat remotely sensed images were first pre-processed using inflight sensor calibration parameters and atmospherically corrected using the flaash algorithm. urban built-up land was then extracted based on the ndbi based continuous built-up index. spatio-temporal changes of built-up land were finally analyzed and statistically summarized with the help of gis. the study results show that the built-up land area had increased from 4063.1 ha to 7163.2 ha in june 1996 and may 2016 which account for 13.3% and 23.4% of the total area, respectively. the urban built-up land area had increased about 10.1% of the total area in asian review of environmental and earth sciences, 2020, 7(1): 61-66 66 © 2020 by the authors; licensee asian online journal publishing group 20 years and tends to expand to the west, southwest, and south of the hma. the results of this study demonstrate that spatio-temporal changes of urban built-up land can be effectively and quickly monitoring and assessed using remotely sensed images. references [1] y. zha, j. gao, and s. ni, "use of normalized difference built-up index in automatically mapping urban areas from tm imagery," international journal of remote sensing, vol. 24, pp. 583-594, 2003. available at: https://doi.org/10.1080/01431160304987. [2] h. xu, "a new index for delineating built-up land features in satellite imagery," international journal of remote sensing, vol. 29, pp. 4269-4276, 2008. available at: https://doi.org/10.1080/01431160802039957. [3] c. l. zhang, f. chen, s. g. miao, q. c. li, x. a. xia, and c. y. xuan, "impacts of urban expansion and future green planting on summer precipitation in the beijing metropolitan area," journal of geophysical research: atmospheres, vol. 114, pp. 1-26, 2009. [4] j. hu, y. liu, and y.-f. sang, "precipitation complexity and its spatial difference in the taihu lake basin, china," entropy, vol. 21, pp. 1-12, 2019. available at: https://doi.org/10.3390/e21010048. [5] r. k. kaufmann, k. c. seto, a. schneider, z. liu, l. zhou, and w. wang, "climate response to rapid urban growth: evidence of a human-induced precipitation deficit," journal of climate, vol. 20, pp. 2299-2306, 2007. available at: https://doi.org/10.1175/jcli4109.1. [6] m. ranagalage, r. c. estoque, and y. murayama, "an urban heat island study of the colombo metropolitan area, sri lanka, based on landsat data (1997–2017)," isprs international journal of geo-information, vol. 6, pp. 1-17, 2017. available at: https://doi.org/10.3390/ijgi6070189. [7] j. tan, y. zheng, x. tang, c. guo, l. li, g. song, x. zhen, d. yuan, a. j. kalkstein, and f. li, "the urban heat island and its impact on heat waves and human health in shanghai," international journal of biometeorology, vol. 54, pp. 75-84, 2010. available at: https://doi.org/10.1007/s00484-009-0256-x. [8] l. liu and y. zhang, "urban heat island analysis using the landsat tm data and aster data: a case study in hong kong," remote sensing, vol. 3, pp. 1535-1552, 2011. available at: https://doi.org/10.3390/rs3071535. [9] k. ford, remote sensing for planners. rutgers, usa: center for urban policy research, 1979. [10] d. lindgren, land use planning and remote sensing vol. 2. the netherlands: taylor & francis, 1984. [11] q. zhang, j. wang, x. peng, p. gong, and p. shi, "urban built-up land change detection with road density and spectral information from multi-temporal landsat tm data," international journal of remote sensing, vol. 23, pp. 3057-3078, 2002. [12] t. d. vu and t. t. nguyen, "spatio-temporal changes of underground coal fires during 2008–2016 in khanh hoa coal field (northeast of viet nam) using landsat time-series data," journal of mountain science, vol. 15, pp. 2703-2720, 2018. available at: https://doi.org/10.1007/s11629-018-4997-z. [13] p. k. gangopadhyay, k. lahiri-dutt, and k. saha, "application of remote sensing to identify coalfires in the raniganj coalbelt, india," international journal of applied earth observation and geoinformation, vol. 8, pp. 188-195, 2006. available at: https://doi.org/10.1016/j.jag.2005.09.001. [14] j. masek, f. lindsay, and s. goward, "dynamics of urban growth in the washington dc metropolitan area, 1973-1996, from landsat observations," international journal of remote sensing, vol. 21, pp. 3473-3486, 2000. available at: https://doi.org/10.1080/014311600750037507. [15] m. kawamura, "relation between social and environmental conditions in colombo sri lanka and the urban index estimated by satellite remote sensing data," in proceeding 51st annual conference of the japan society of civil engineers, 1996. [16] a. as-syakur, i. adnyana, i. w. arthana, and i. w. nuarsa, "enhanced built-up and bareness index (ebbi) for mapping built-up and bare land in an urban area," remote sensing, vol. 4, pp. 2957-2970, 2012. [17] d. stathakis, k. perakis, and i. savin, "efficient segmentation of urban areas by the vibi," international journal of remote sensing, vol. 33, pp. 6361-6377, 2012. available at: https://doi.org/10.1080/01431161.2012.687842. [18] c. he, p. shi, d. xie, and y. zhao, "improving the normalized difference built-up index to map urban built-up areas using a semiautomatic segmentation approach," remote sensing letters, vol. 1, pp. 213-221, 2010. available at: https://doi.org/10.1080/01431161.2010.481681. [19] a. rasul, h. balzter, g. r. f. ibrahim, h. m. hameed, j. wheeler, b. adamu, s. a. ibrahim, and p. m. najmaddin, "applying built-up and bare-soil indices from landsat 8 to cities in dry climates," land, vol. 7, pp. 1-13, 2018. available at: https://doi.org/10.3390/land7030081. [20] t. m. nguyen, t.-h. lin, and h.-p. chan, "the environmental effects of urban development in hanoi, vietnam from satellite and meteorological observations from 1999–2016," sustainability, vol. 11, pp. 1-24, 2019. available at: https://doi.org/10.3390/su11061768. [21] a. esri, arcmap10.2. redlands, california, usa: esri, 2014. [22] t. d. vu and t. t. nguyen, "remote sensing and gis-based river bank accretion erosion assessment in the confluence of thaoda-lo rivers, north east of vietnam," environment asia, vol. 11, pp. 27-44, 2018a. [23] s. m. adler-golden, m. w. matthew, l. s. bernstein, r. y. levine, a. berk, s. c. richtsmeier, p. k. acharya, g. p. anderson, j. w. felde, and j. gardner, "atmospheric correction for shortwave spectral imagery based on modtran4. imaging spectrometry v," in international society for optics and photonics, 1999, pp. 61-69. [24] a. berk, g. p. anderson, l. s. bernstein, p. k. acharya, h. dothe, m. w. matthew, s. m. adler-golden, j. h. chetwynd jr, s. c. richtsmeier, and b. pukall, "modtran4 radiative transfer modeling for atmospheric correction," in optical spectroscopic techniques and instrumentation for atmospheric and space research iii, 1999, pp. 348-353. [25] o. orhan, s. ekercin, and f. dadaser-celik, "use of landsat land surface temperature and vegetation indices for monitoring drought in the salt lake basin area, turkey," the scientific world journal, vol. 2014, pp. 1-11, 2014. [26] w. s. logan, "the cultural role of capital cities: hanoi and hue, vietnam," pacific affairs, vol. 78, pp. 559-575, 2005. available at: https://doi.org/10.5509/2005784559. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 48 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 48-61, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.48.61 © 2021 by the authors; licensee asian online journal publishing group mineralization characterization of psammitic rocks in efon-alaaye and environs using remote sensing and field studies ayodele olusiji samuel1 asubiojofola emmanuel2 ( corresponding author) 1,2department of applied geology, the federal university of technology, akure, nigeria. 1email: samuelayodeleolusiji@yahoo.com tel: +2349060414142 2email: asubiojofe@futa.edu.ng tel: +2347069107182 abstract this paper analyses remotely sensed data over a part of the psammitic rocks in efon-alaaye and environs to elucidate its geology and structural framework as well as delineate the potential zones of mineralization. the study area belongs to the precambrian basement complex terrain of southwestern nigeria and lies within the eastern unit of the ilesha schist belt. the lithologic units comprise schistose quartzites, quartz schists, quartz-mica-schists, and granitic gneisses. landsat 8 satellite imagery and shuttle radar topography mission imagery (srtm), both of path 190 and row 055, were used for the purpose of this study. a total of 138 lineaments of total length of 147.948 km, were automatically extracted from both data. rose diagram showed that the lineaments are bi-directional, with major lineaments trending ne-sw, e-w and the subsidiary ones in the nw-se direction. these lineaments are mostly mapped on the schistose quartzites. also, n-s trending faults were mapped from the digital elevation model map generated from the srtm data which was confirmed to be reverse fault based on field studies. the mineral alteration map generated revealed signatures of gold, iron oxides and silica minerals, while the mineralization potential map was done with reference to established geological settings of the area in conjunction with the structural elements such as folds, faults, joints and fractures mapped and measured on the field. these structures are typical of gold mineralization and associated metallic minerals in the ilesha schist belt. this study also confirmed that mineralization in the study area is structurally controlled and type of mineralization is epigenetic in nature as a result of favorable ground preparation. keywords: efon-alaaye, lithologic units, mineralization, lineament, structures, signature, imagery. citation | ayodele olusiji samuel; asubiojofola emmanuel (2021). mineralization characterization of psammitic rocks in efon-alaaye and environs using remote sensing and field studies. asian review of environmental and earth sciences, 8(1): 48-61. history: received: 3 september 2021 revised: 1 october 2021 accepted: 28 october 2021 published: 26 november 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: both author really appreciates the effort and support of dr. o. s. ayodele (associate professor, department of applied geology, federal university of technology, akure). their sincere thanks to the editor and the anonymous reviewer for providing constructive comments on the original manuscript, which significantly enhanced the quality of this work. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 49 2. geological setting ........................................................................................................................................................................... 50 3. materials and methodology ........................................................................................................................................................... 50 4. result and discussion ..................................................................................................................................................................... 55 5. conclusions ....................................................................................................................................................................................... 60 references .............................................................................................................................................................................................. 60 mailto:samuelayodeleolusiji@yahoo.com mailto:asubiojofe@futa.edu.ng http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.doi.org/10.20448/journal.506.2021.81.48.61 https://orcid.org/0000-0003-2065-5947 https://orcid.org/0000-0003-2178-189x asian review of environmental and earth sciences, 2021, 8(1): 48-61 49 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature: this paper unravels the geology and structure as well as the mineralization potentials of the psammites in efon-alaaye and environs which is known as the “efon psammite formation”. this formation is a combination of several meta-sedimentary sequences of rocks units in the study area by using multi-spectral remote sensing techniques and detailed geo-structural mapping. 1. introduction the study area belongs to the basement complex terrain of southwestern nigeria, and lies within the eastern unit of the ilesha schist belt figure 1. this unit comprises of the metasedimentary assemblages which includes; quartzite, schists, amphibolites, quartz schist, mica schist. also the unit comprises of migmatite--quartzite complex which includes; granitic gneiss, banded gneiss, migmatite, quartzo-feldspathic granulite with gneiss [1]. the metasedimentary assemblages has been hitherto referred to as the effonpsammite formation [2]. the northern flanks of the study area okemesi figure 1, have been widely investigated by several workers such as [1];[3];[4]. they studied the area using remote sensing methods, in terms of its geology, structures, and mineralization potentials. however, there seems to be paucity of information as regard the nature, geology, structures, and mineralization potentials of the psammites in efon area. figure-1.geology of ilesha schist belt, also showing the study area. [1, 5]. asian review of environmental and earth sciences, 2021, 8(1): 48-61 50 © 2021 by the authors; licensee asian online journal publishing group remote sensing has been a versatile tool in geology for the understanding of regional mapping, structural interpretation and to aid prospecting of mineral deposits [6]. understanding the geology and structure of a terrain plays an important role in mineral resource estimation, evaluation and exploration [7-9]. structural mapping is the identification and characterization of structural expression and these structures includes faults, folds, joints and fractures. various types of remotely sensed data have been used for geologic mapping such as aerial photographs and satellite derived multispectral images for morphological and lineament mapping [10-12]. in this case, multispectral reflectance data (landsat 8 satelite imagery) and shuttle radar topographic mission (srtm) data were used for the purpose of this research work. wright, et al. [13] suggested that mineralization in the ilesha schist belt occurs in the form of veins, lenses, stringers, reefs and as quartz-feldspar-tourmaline rocks. while akande, et al. [14] and ajayi and ogedengbe [15] have suggested that gold mineralization occurs in the form of primary and alluvial deposits in the study area. these structures therefore allow the application of the remote sensing method in delineating them in terms of trend, densities and aerial extent [7]. this study is therefore aimed at establishing the geology and delineating geological structures that could host mineralization in the area using remote sensing method. 2. geological setting the study area figure 2 is situated in efon local government area of ekiti state and part of osun state south-west nigeria, with an approximated area of 100 km2, it can be located within longitudes 4º52' 0'' e and 4º57'' 0"e, latitudes 7º35' 0"n and 7º 41' 0"n. it is dominated by prominent north-south trending ridges, separated by relatively lowland figure 3. this is an indication of an active area of orogeny and other geological processes [16], hence the ridges are structural markers that delineate folds and lineaments. the study area also belongs to the basement complex terrain of southwestern nigeria and lies within the eastern unit of the ilesha schist belt. the lithologic units comprises schistose quartzite, quartz schist, mica-quartz-schist with subordinate granitic gneiss figure 4 [16-18]. however, the schistose quartzites in the study area are pelitic because they are metamorphosed from sandstone and tend to form good topographic features [16]. the schistose quartzite occupies about 50% of the entire study area occupying the central part figure 5. the texture of the rocks range from medium-fine grained and the colors vary from purple, brown, yellow to milky. they also display joints of different magnitudes and orientations and several joint sets trending ne-sw, e-w and nw-se [17, 19]. the quartz schists which is formed at the base of the schistose quartzite ridge occur as low-lying outcrops. it exhibits strong foliation with its strike orientating generally to the north and steeply dipping to the east and west. the quartz-mica-schist is generally low-lying and steeply dipping to the west. the granitic gneiss which is a highly resistive rock in the area has mineralogical banding of felsic minerals such as quartz and feldspar with streaks of biotite. it has a medium to coarse-grained texture and possessing moderate to strong foliation [18]. generally, the rock of the study area has been subjected to at least two deformational episodes [18, 20]. the early deformation includes regional metamorphism in the area, causing the rocks to trend n-s, and also the formation of mega folds (synformantiformassymetrical and overturned fold) figure 4. the recent deformation episode gave rise to fracturing and faulting of the rocks [1, 16, 21, 22]. 3. materials and methodology landsat 8 satellite imagery figure 5 and srtm imagery figure 6. both of path 190 and row 055, were downloaded from usgs website (www. usgs.gov), for the purpose of this study. the automatic lineament extraction process was carried out with line module of pci geomatica 2015 software, based on automatic detection algorithms (canny algorithms). the arcgis 10.3 software was used to digitize the lineaments, produce the density map, digital elevation model (dem) map, and mineral alteration map. while rockworks 17 software was used to produce the lineament rose diagram. firstly the landsat 8 data was uploaded to the arcgis 10.3 software and principal component analyses (pca) was carried out to get the best imagery suitable for the extraction of lineaments. this imagery and the srtm imagery were then exported to pci geomatica 2015 software, where the lineaments were automatically extracted. the lineaments extracted were exported as shapefile into the arcgis 10.3 for the production of the lineament density. the lineament density of the area was computed using the line density tool within arcgis 10.3. it is expressed in km2. rose diagram of the lineaments was generated using the rockworks 17 software. this was done after the lineaments extracted was exported into the arcgis 10.3 environment where it was prepared by creating x_start, x_end, y_start, y_end, x-mid and y_mid coordinate using the calculate geometry tool and exported in cad format. the rose diagram was finally generated in rockworks 17 software and exported as a jpeg image. proper band combinations for minerals were factored in using arcgis 10.3 software to produce the mineral alteration map of the study area it was discovered that band 2, 4, 5, 6, and 7 are the most suitable for the minerals present within the study area. the digital elevation model map was generated from the processing of the srtm imagery over the study area in the arcgis environment. http://www.earthexplorer.usgs.gov/ asian review of environmental and earth sciences, 2021, 8(1): 48-61 51 © 2021 by the authors; licensee asian online journal publishing group figure-2. map of the study area located within ekiti and osun states inset: map of nigeria showing the study area. asian review of environmental and earth sciences, 2021, 8(1): 48-61 52 © 2021 by the authors; licensee asian online journal publishing group figure-3. topographic map of the study area [23]. asian review of environmental and earth sciences, 2021, 8(1): 48-61 53 © 2021 by the authors; licensee asian online journal publishing group figure-4. structural geological map and cross section of the study area. quartz-mica schist quartz schist ! ! ! ! ! ! ! ! !!!!! schistose quartzite ! ! ! ! ! ! ! ! !!!!! granitic gneiss fractures okeiia orisi efon-alaaye erinmo iwaji erinmo ipole asian review of environmental and earth sciences, 2021, 8(1): 48-61 54 © 2021 by the authors; licensee asian online journal publishing group figure-5. landsat 8 imagery of the study area (www. usgs.gov). http://www.earthexplorer.usgs.gov/ asian review of environmental and earth sciences, 2021, 8(1): 48-61 55 © 2021 by the authors; licensee asian online journal publishing group figure-6. srtm imagery of the study area (www. usgs.gov). 4. result and discussion 4.1. lineament map the lineament map superimposed on the geological map of the study area is presented in figure 7. the major trends of the lineaments are in the ne-sw, e-w directions, with the subsidiary ones trending nw-se direction. schistose quartzite are the most and highly fractured rock in the study area with the fracture mostly trending nesw direction, followed by the quartz schist. the granitic gneiss and the quartz-mica-schist show little fracturing because of their ductile behaviour. the highly fractured nature of the schistose quartzite is because the rock is very brittle in nature, highly brittle than the quartz schist, granitic gneiss and the quartz-mica-schist. the response of these rocks to deformation is dependent on their mineral compositions, temperature, pressure and depth. http://www.earthexplorer.usgs.gov/ asian review of environmental and earth sciences, 2021, 8(1): 48-61 56 © 2021 by the authors; licensee asian online journal publishing group figure-7. lineament map of the study area. 4.2. rose diagram the rose diagram generated for the lineaments is presented in figure 8. a total of 138 lineaments were mapped from the remote sensing data. the total length of the lineaments are 147.948.08 km. the rose diagram shows that the linear structures in the study area are bi-directional, which indicated major fractures are in the nesw, e-w, and the subsidiary ones in nw-se directions. figure-8. rose diagram generated from the lineament map. 4.3. lineament density map the lineament density map of the study area is presented in figure 9. the map revealed that higher fracture densities occur mostly on the schistose quartzite. this can be attributed to the brittle and shearing nature of the rock caused by the thermos-tectonic influence of the ifewara mega shear, while there is paucity of fractures on the asian review of environmental and earth sciences, 2021, 8(1): 48-61 57 © 2021 by the authors; licensee asian online journal publishing group granite gneiss. ramesh, et al. [7] established that mineralization are usually associated with areas of high density fractures; hence the schistose quartzite units in the efon area are likely to host mineralization. figure-9. lineament density map of the study area. 4.4. mineral alteration map the mineral alteration map is presented in figure 10. band rationing method was used to map out area that shows signatures of gold, iron oxides, base metals and silica minerals in the study area. from the mineral alteration map, signature of gold, iron oxides and silica mineral are widespread and majorly seen on the highly fractured schistose quartzite rock; the gold signature becomes more evident around the schistose quartzite located within the efon town, while the signatures of iron oxide are evident on the quartz schist, granitic gneiss and quartz-micaschist. this is an indication of gemstone mineralization. the base metals signatures are scarcely distributed throughout the entire study area. asian review of environmental and earth sciences, 2021, 8(1): 48-61 58 © 2021 by the authors; licensee asian online journal publishing group figure-10. mineral alteration map of the study area. 4.5. digital elevation map the digital elevation map (dem) of the study area is presented in figure 11. this map shows that the schistose quartzite are generally high in elevation and ranges from 445m to 728m, while the quartz schist and the quartz-mica-schist are generally low-lying ranging from 295m to 444m, while the granitic gneiss appears to have moderate elevation ranging 379m to 616m. a likely fault was detected from the dem map of the study area figure 11 and also from visual inspection of the landsat 8 imagery figure 5. the sharp contrast between the lowest elevation of the quartz schist and highest elevation of the schistose quartzite is suspected to be a reverse fault. this is similar to faults established by odeyemi [1] and anifowose, et al. [22] in the ilesha schist belt, they reported that these faults are associated with the ifewara fault and are indicative of possible subduction zone in an oceanic basin. also from the dem interpretation, it can be observed that there is a possibility that the rocks of the entire study area has been folded and refolded. asian review of environmental and earth sciences, 2021, 8(1): 48-61 59 © 2021 by the authors; licensee asian online journal publishing group figure-11. digital elevation map (dem) map of the study area. 4.6. mineralization potential map figure 12 shows the mineralization potential map of efon area of the ilesha schist belt from the lineament map, lineament density map, mineral alteration map, and digital elevation model (dem) map. areas, where the delineated structures on the lineament map coincide with structures on the dem map and mineral signatures on the mineral alteration map are typical of mineralized zones. the mineralization map also reveals potential zones where ore deposits can be assessed such as around efon-alaaye, erinmo and ipole figure 12. the structural pattern revealed that considerable mineralisation within the area lies predominantly along ne-sw direction and rarely along w-e trending structures and along the n-s trending fault. the overlay of the mineralisation map with the geologic map of area suggests that mineralisation is associated more with the schistose quartzite and contact between rocks. asian review of environmental and earth sciences, 2021, 8(1): 48-61 60 © 2021 by the authors; licensee asian online journal publishing group figure-12. mineralization potential map superimposed on geology 5. conclusions the study area is underlain by schistose quartzites, quartz schists, quartz-mica-schists and granitic gneisses. this study revealed that the schistose quartzites rocks are the most fractured rock, it has more lineaments densities and the lineaments are trending ne-sw, e-w and nw-se. these lineaments are similar to structures that are associated to the pan-african deformation to host mineralization in the ilesha schist. mineralization is observed to be distributed mainly on schistose quartzite unit. signatures of gold, iron oxide, silica mineral are wide spread on the schistose quartzite; this is an indication of metallic and gemstone mineralization. generally the area has been faulted and folded resulting from two deformational episodes. references [1] i. b. odeyemi, "a comparative study of remote sensing images of the structure of the okemesi fold belt, nigeria," itc journal, vol. 1931-1, pp. 77-81, 1993. [2] f. h. hubbard, "precambrian crustal development in western nigeria: indications from the iwo region," geological society of america bulletin, vol. 86, pp. 548-554, 1975. [3] a. anifowose and a. borode, "a photogeological study of the fold structure in okemesi area, nigeria," journal of mining and geology, vol. 43, pp. 125-130, 2007. [4] o. s. ayodele, "remote sensing and geological study of oke-mesi area s.w nigeria," african journal of science technology innovation and development, vol. 1, pp. 134-137, 2010. [5] nigeria geological survey agency, "geological map of ilesha schist belt," 2006. [6] f. d. van der meer, h. m. van der werff, f. j. van ruitenbeek, c. a. hecker, w. h. bakker, m. f. noomen, m. van der meijde, e. j. m. carranza, j. b. de smeth, and t. woldai, "multi-and hyperspectral geologic remote sensing: a review," international journal of applied earth observation and geoinformation, vol. 14, pp. 112-128, 2012. [7] c. p. ramesh, p , t. jayaram, and g. jayalakshmi, "an analysis of lineaments and mineral occurrences of veligallu schist belt and surroundings, eastern dharwar craton, india using remote sensing & gis," journal of multidisciplinary engineering science and technology (jmest), vol. 1, pp. 198-204, 2014. [8] d. b. waele, m. lacorde, m. cunningham, and b. jupp, "understanding geology and structure: an essential part of mineral resource estimation," aseg extended abstracts, vol. 2018, pp. 1-8, 2018.available at: https://doi.org/10.1071/aseg2018abm2_2f. [9] j. d. a. uwiduhaye, j. c. ngaruye, and h. saibi, "defining potential mineral exploration targets from the interpretation of aeromagnetic data in western rwanda," ore geology reviews, p. 103927, 2020. [10] j. wang and p. j. howarth, "use of the hough transform in automated lineament," ieee transactions on geoscience and remote sensing, vol. 28, pp. 561-567, 1990.available at: https://doi.org/10.1109/tgrs.1990.572949. [11] k. koike, s. nagano, and m. ohmi, "lineament analysis of satellite images using a segment tracing algorithm (sta)," computers & geosciences, vol. 21, pp. 1091-1104, 1995.available at: https://doi.org/10.1016/0098-3004(95)00042-7. asian review of environmental and earth sciences, 2021, 8(1): 48-61 61 © 2021 by the authors; licensee asian online journal publishing group [12] a. karnieli, a. meisels, l. fisher, and y. arkin, "geological linear features from digital remote sensing data using a hough transform," photogramm. eng. remote sens, vol. 62, pp. 525-531, 1996. [13] j. b. wright, d. a. hastlings, w. b. jones, and h. r. williams, geology and mineral resources of west africa. london: george allen and unman, 1985. [14] s. o. akande, a. hoffknecht, and b. d. erdtmann, "rank and petrographic composition of selected upper cretaceous and tertiary coals of southern nigeria," international journal of coal geology, vol. 20, pp. 209-224, 1992. [15] t. ajayi and o. ogedengbe, "opportunity for the exploitation of precious and rare metals in nigeria," prospects for investment in mineral resources of southwestern nigeria,(ed.) aa elueze, vol. 1526, pp. 15-26, 2003. [16] o. s. ayodele, "litho-geochemical and petrogenetic characteristics of some massive and schistose quartzites in ekiti state, southwestern nigeria," international journal of science inventions today, vol. 3, pp. 013-040, 2014. [17] o. okunlola, o. adeigbe, and o. oluwatoke, "compositional and petrogenetic features of schistose rocks of ibadan area, southwestern nigeria," earth sciences research journal, vol. 13, pp. 119-133, 2009. [18] b. adeoti and c. t. okonkwo, "structural geology of the basement complex rocks in iwaraja area, southwestern nigeria," international letters of natural sciences, vol. 58, pp. 16-28, 2016.available at: https://doi.org/10.18052/www.scipress.com/ilns.58.16. [19] a. akinlalu, a. adelusi, g. olayanju, k. adiat, g. omosuyi, a. anifowose, and b. akeredolu, "aeromagnetic mapping of basement structures and mineralisation characterisation of ilesa schist belt, southwestern nigeria," journal of african earth sciences, vol. 138, pp. 383-391, 2018.available at: https://doi.org/10.1016/j.jafrearsci.2017.11.033. [20] m. o. oyawoye, "the basement complex of nigeria, in: dessauvagie, t.f.j. and whiteman, a.j., eds., african geology," ed ibadan: university of ibadan press, 1972, pp. 67-99. [21] a. gandu, s. ojo, and d. ajakaiye, "a gravity study of the precambrian rocks in the malumfashi area of kaduna state, nigeria," tectonophysics, vol. 126, pp. 181-194, 1986.available at: https://doi.org/10.1016/0040-1951(86)90227-1. [22] a. y. b. anifowose, i. b. odeyemi, and a. m. borode, "the tectonic significance of the ifewara-zungeru megastructure in nigeria," in proceedings of the 1st international workshop on geodesy and geodynamics, centre for geodesy and geodynamics, toro, bauchi state, nigeria, 2006, pp. 17-28. [23] fsn, "topographic map series :ilesha sheet 243 (sw & se). scale 1:50,000," 1966. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://www.scipress.com/ilns.58.16 18 © 2022 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 9, no. 1, 18-22, 2022 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v9i1.4339 © 2022 by the authors; licensee asian online journal publishing group quality control compliance as an environmental response to sustainability in the nigerian construction industry amadi alolote ibim1 amadi kelvin chijioke2 ( corresponding author) 1department of quantity surveying, rivers state university, p.m.b 5080, port harcourt, nigeria. email: amadialolote@yahoo.com 2department of general studies, elechi-amadi polytechnic, port harcourt, nigeria. email: kamadi620@gmail.com abstract the concept of sustainability has become integral to the environmental dialect within the building construction industry. at present, providing an avenue by which the construction industry can meet its sustainability obligations has remained a topical issue globally. an environmentally oriented movement toward sustainability in building construction, however, still hinges on the traditional principles of cost, quality, and performance. this paper x-rays the unethical performance traits evident in the construction industry in nigeria and the project delivery practices by indigenous firms that significantly influence the quality and thus the sustainability of construction output. issues associated with quality control compliance are statistically analysed to determine existing trends. multivariate analysis is deployed to measure the degree to which quality control parameters explain the participation level of indigenous local contractors in executing government projects. the study mathematically expresses the relationship between quality control adherence and indigenous participation in the execution of government contracts. the statistical analysis shows that the five quality control independent variables (internal organizational factor; the level of enlightenment; adequacy of designs; conducting of relevant tests and supervisory adherence) explain 47% of the variation in the level of indigenous participation. poor quality control associated with the execution of contracts by indigenous construction companies in nigeria may thus partly account for the low level of indigenous participation evident in the construction industry. keywords: construction industry, ethics, indigenization, local content, projects, quality control. citation | ibim, a. a., & chijioke, a. k. (2022). quality control compliance as an environmental response to sustainability in the nigerian construction industry. asian review of environmental and earth sciences, 9(1), 18–22. 10.20448/arees.v9i1.4339 history: received: 2 september 2022 revised: 10 october 2022 accepted: 18 november 2022 published: 14 december 2022 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: both authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 19 2. method of study ............................................................................................................................................................................... 19 3. results and findings ....................................................................................................................................................................... 20 4. conclusion ......................................................................................................................................................................................... 21 references .............................................................................................................................................................................................. 22 mailto:amadialolote@yahoo.com mailto:kamadi620@gmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v9i1.4339 https://orcid.org/0000-0002-0569-6604 https://orcid.org/0000-0001-5101-6799 asian review of environmental and earth sciences, 2022, 9(1): 18-22 19 © 2022 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the study statistically explores the cause-effect relationship between the level of quality control by indigenous contracting firms in nigeria and their level of participation in public projects. this is against the backdrop of the paucity of empirical literature, whereby most studies only report descriptive outcomes on the variables. 1. introduction there have been repeated calls for increased “local content” i.e., indigenous participation in the construction of capital projects in nigeria, against the backdrop of foreign firms’ domination of the construction sector. two major concerns involving project delivery by indigenous construction firms however can be identified; one is the quality of construction output in the industry [1]. one is the quality of construction projects executed by local construction firms in nigeria as evidenced by the several reported cases of premature building failure [2, 3]. the other is the widespread notion that unethical performance plagues indigenous construction companies in nigeria [4]. quality assurance epitomizes the confidence that construction works adhere to the design requirements of durability, safety, and functionality as well as serviceability, economy, and aesthetics okereke [5]; lakshmi [6]; adekeye, et al. [7]. abdulkareem and adeoti [1] study reveals that the primary measures of quality control carried out on building sites in nigeria are owners and unskilled supervision; supervision by skilled technical personnel and supervision by professional consultants. abdulkareem and adeoti [1] study however showed that the majority of construction projects in nigeria are supervised by the building owners, and in some cases, semiskilled or unskilled personnel are engaged to carry out the supervision [3, 4, 8]. in these instances, adherence to quality standards is not ensured, and the supervisors lack the technical and professional capacity to control quality. non-adherence to drawings and material specifications is often the case and the contractors stand to gain financial benefits. only a handful of individual construction projects are supervised by skilled professionals [6, 9]. supervision by professionals is mostly found on government projects, where they serve as consultants to the government, by reporting and evaluating the progress of works at regular intervals. previous research has evaluated compliance with government regulatory policies, the perception of professionals, and barriers to adherence to quality control [2, 8, 10, 11]. ethical issues have however plagued the performance of government projects in different parts of the world rodriguez, et al. [12]; bowen, et al. [13]; rose-ackerman [14]; sichombo, et al. [15]. wasserman [16] asserted that ethics encompasses the thought, dialectal, cognitive processes, and decisions that dictate the choices made by people in their daily lives concerning their effect on the well-being of others. this definition aptly captures the nigerian scenario as there appears to be a twisted and astonishingly flexible value system in the general acceptance level of what is regarded as ethical. bribery and corruption which is rife in the system of governance and organizational setup, both in private and public holdings seem to constitute an acceptable standard of conduct amongst nigerians [7]. as such, genuine outcry against perceived misappropriation of public funds allocated to various sectors of the economy and for infrastructural development are “swept under the rug” by the powers that be. the “share the national cake” mentality is thus a major obstacle in the wheel of progress as to the level of economic growth and development that the country has the potential to achieve [17]. the impact of this value system is far-reaching in its effect, as it has pervaded across all facets of human endeavor and trickled down along generational lines. unethical and corrupt practices in the country popularly tagged the “nigerian factor” have negatively affected the construction industry and the level of quality assurance in nigeria. from the professionals who are the custodian of the confidential information, to the contractors and even hired labour on-site, corruption has eaten deep into the fabric of industry practice in nigeria. professionals whose major obligation is to ensure that the successful contractor is capable of offering good quality output at the lowest tender figure may disregard integrity and the ethics of their profession in return for financial gains. 2. method of study a survey of construction professionals was carried out the assess the nature of quality control practices in port harcourt metropolis. this is similar to the study by opara and uche [10]. the study considered the current volume and spread of major construction projects in the country. data for this purpose was obtained from precoded questionnaires that were administered to a random selection of building professionals as contained from the listing of professionals and registered contractors in the study area. the key objective of the data analysis was to measure the degree to which quality control parameters explain the level of participation of indigenous contractors in the execution of government projects. the study administered well-structured and sectioned questionnaires which were distributed online. these were based on a representative sample of 292 respondents made up of consultants, clients, contractors, and allied professionals in various locations as shown in table 1. table 1. distribution of respondents. types of respondents no consultants 26 client and client representative 31 contractors 72 other professionals 122 total 251 the response rate to distributed questionnaires however was 86% with a total of 251 returned. most of the respondents were registered in one or more professional bodies with a significant number of years of working experience. the analysis explored two sets of variables for the study, targeted at extracting quality control measures adopted by respondents and project procurement processes and activities that were mostly associated with unethical and corrupt practices. the basic sequence of the analytical strategy that was adopted to obtain asian review of environmental and earth sciences, 2022, 9(1): 18-22 20 © 2022 by the authors; licensee asian online journal publishing group relevant and objective results from data collated during fieldwork is as follows: the analysis begins by examining existing quality control measures adhered to by respondents in their respective locations and a quantitative value obtained for the qualitative adequacy of these measures in determining industry output. in terms of the percentage frequency distribution. the qualitative adequacy value (qav) for the study location was obtained based on the product of the arithmetic mean of the qualitative index that would be assigned to these variables on a 3-point rating scale and the frequency of pre-coded responses as a percentage of the cumulative. criteria for determining adequacy were based on a predetermined interval classification of computed qavs, the maximum value of the index being 1.0. the assessment of the variables was done based on the mean weighted scores to obtain the overall rating for the level of adherence to quality control. as a final step in this phase, a multi-variate multiple classification analysis (mca) [18] was then deployed to explain the level of indigenous participation in government construction contracts as extracted from questionnaire responses, relative to the number of major government contracts executed. mca is a bivariate response of regression analysis technique that predicts the dependent variable based on membership/categories of the independent predictor variables. mca can be mathematically expressed as: 𝑌𝑖𝑗…𝑛 = 𝑌 + 𝑎𝑖 + 𝑏𝑗+ . . … . . … 𝑒𝑖𝑗 … . . .𝑛 (1) three sets of coefficients are generated via multiple classification analysis: eta/eta2, beta/ beta2, and multiple correlation coefficient r-squared (r2). eta/eta2: eta values are indicative of the predictor ability of the specified categories in explaining the variation triggered in the dependent variable. eta as a correlation ratio is thus indicative of the percentage of the total sum of squares that is explained by the predictor variable. beta/beta2: similar to the eta statistics, the beta/beta2 represents the explanatory capacity of the predictor variables but is computed using the adjusted as opposed to the raw means. beta statistics thus reflect the degree of explanation provided by the predictor variable to account for the variation in the dependent variable after adjustments have been made for the combined effects of other predictor variables. multiple correlation coefficient (r-squared): the multiple correlation coefficient provides an aggregated explanation of the amount of variation in the dependent variable as collectively accounted for by the predictor variables. this technique will be used to analyse generated data collated from responses to structured questionnaires to develop a multivariate model mathematically displaying expression for the association between the degree of quality control adherence and the extent of indigenous participation in the execution of government contracts as indicated by responses as to the number of major government projects executed/participated in by respondents. 3. results and findings table 2 is a breakdown of the acceptability criteria used in rating the level of compliance with quality control. table 2. quality control compliance criteria rating for acceptability. percentage rating 81% 100% excellent 66% 80% very good 51% 65% good 36% 50% fair 0% 35% poor table 3 is a summary of the questionnaire responses provided by the respondents on the quality control measures adopted. table 4 shows the number of major government/public projects executed by the sampled indigenous contractors. the weighted values of these responses were thus analysed using mca to produce a multiple regression model for the level of indigenous participation. table 5 shows the results of the mca indicating the quality control compliance variables in accounting for the variation in indigenous participation. table 5 shows that taken together, the five quality control independent variables (internal organizational factor; the level of enlightenment; adequacy of designs; conducting of relevant tests, and supervisory adherence) explain 47% of the variance reported in the level of indigenous participation. as the findings show, 41.2% of the respondents were of the view that the level of quality control adherence is fair. however, the majority of the respondents (53.3%) were not of this view. pointers to specific areas of poor-quality control are evident in the response pattern. asian review of environmental and earth sciences, 2022, 9(1): 18-22 21 © 2022 by the authors; licensee asian online journal publishing group table 3. analysis of questionnaire responses on construction industry quality control measures. s/no items yes % no % no response % 1. internal organizational factor a. observance of q.c in the company 52.0 38.8 9.2 b. record keeping of quality control results 46.8 48.0 5.2 c. presence of communication between quality control professionals and management 71.6 7.4 11.0 2. level of enlightenment a. enlightenment of tradesmen 35.2 60.8 4.0 b. suppliers and contractors are aware of q.c provision in the project. 22.8 70.8 6.4 3. adequacy of designs 2. adherence at the design stage 56.4 42.0 1.61 3. adequate specification and detailing of elements 92.4 4.0 3.6 4. conduction of relevant tests a. conduction of geotechnical analysis for foundation 4.0 78.0 18.0 b. conduction of concrete tests 36.0 53.2 10.8 c. conduction of aggregate tests 20.8 69.6 9.6 d. conduction of cement tests 2.8 97. 2 0.0 e. reinforcement strength tests as to q.c 64.0 32.0 4.0 5. supervisory adherence a. project supervisors normally insist on quality control of materials 62.4 34.0 3.6 b. town planning and relevant agencies are involved in q.c compliance 14.0 78.8 7.2 c. adequate checks by the project owner’s representative for defective work before approval of payment 36.9 53.7 9.5 mean % 41.2 53.3 5.5 rating fair table 4. number of major government/public projects executed by respondents. number of government projects executed % of respondents average no of years of working experience 0 – 5 45 7 6 -10 17 16 11 – 15 23 12 15 – 20 9 13 < 20 6 22 table 5. explanatory variation in the level of indigenous participation in the execution of government contracts. s/no explanatory variables eta beta 1 internal organizational factor 0.25 0.20 (4) 2 level of enlightenment 0.23 0.17 (5) 3 adequacy of designs 0.36 0.50 (1) 4 conducting relevant tests 0.22 0.41 (2) 5 supervisory adherence 0.10 0.24 (3) r2 = 0.47 4. conclusion this study has highlighted issues of quality control related to indigenous construction companies as an explanation for the low level of indigenous participation in government projects. this is also considered to be closely linked to ethical issues which plague the nigerian construction industry, and which have been a cause for public concern. as the study reiterates, in the nigerian scenario there appears to be a twisted and astonishingly flexible value system in the general acceptance level of what is regarded as ethical. bribery and corruption which is rife in the system of governance and organizational setup, both in private and public holdings seem to constitute an acceptable standard of conduct amongst nigerians. as such, the genuine outcry against perceived misappropriation of public funds allocated to various sectors of the economy and for infrastructural development are “swept under the rug” by the powers that be. the “share the national cake” mentality is thus a major obstacle in the wheel of progress as to the level of economic growth and development that the country has the potential to achieve. the impact of this value system is far-reaching in its effect, as it has pervaded across all facets of human endeavor and trickled down along generational lines. unethical and corrupt practices in the country popularly tagged the “nigerian factor” has negatively affected the construction industry and the level of quality assurance in nigeria. from the professionals who are the custodian of the confidential information, to the contractors and even hired labour on-site, corruption has eaten deep into the fabric of industry practice in nigeria. nonetheless, quality control issues such as the level of enlightenment; internal organizational factors; adequacy of designs; supervisory adherence, and conducting of relevant tests have been empirically shown to affect the level of indigenous participation in government projects. tackling these issues alongside the underlying ethical menace which pervades the construction industry will create a more sustainable backdrop for ensuring quality control in public projects. against this backdrop, the following recommendations are preferred: • new laws should be promulgated with more stringent measures to curb ethical corrosion. • one-man construction companies should be banned, and rigorous background checks should be carried out to ascertain the competence of contractors. • e-contracting along with the providing of necessary performance bonds should be promoted to ensure a higher level of transparency in public project procurement. asian review of environmental and earth sciences, 2022, 9(1): 18-22 22 © 2022 by the authors; licensee asian online journal publishing group references [1] y. a. abdulkareem and k. a. adeoti, "quality control compliance in the nigerian construction industry: a case study of projects in kwara state," global journal of research engineering, vol. 11, pp. 25-32, 2010. [2] l. o. oyedele, b. e. jaiyeoba, k. o. kadiri, s. o. folagbade, i. k. tijani, and r. o. salami, "critical factors affecting construction quality in nigeria: evidence from industry professionals," international journal of sustainable building technology and urban development, vol. 6, pp. 103-113, 2015.available at: https://doi.org/10.1080/2093761x.2015.1033662. [3] h. e. opara and p. a. okereke, "critical variable in quality control of public building projects in south east nigeria," international journal of research and advancement in engineering science, vol. 6, pp. 26 -29, 2017. [4] o. olugbekan, "corruption in engineering projects and how to check in nse," in paper delivered and submitted to nigerian society of engineers. ibadan-nigeria, 2001, p. 25. [5] p. okereke, "towards effective building materials development, testing and control in nigeria," inter-world journal of science and technology, owerri, vol. 1, pp. 34-43, 2001. [6] r. lakshmi, "quality control and quality assurance in building construction," in national conference on research advances in communication, computation electrical science and structures (ncraccess-(2015), 2015. [7] a. adekeye, s. adebara, d. omajali, and y. yakubu, "perception of professionals on quality control factors in project constructions," international journal of science, engineering & environmental technology, vol. 2, pp. 76-83, 2017. [8] p. longtau, a. m. justina, s. t. majidadi, and m. gillian, "assessment factor militating against adherence to quality control in building construction," international journal of scientific and engineering research, vol. 7, pp. 1225-1226, 2016. [9] y. lawal, "maintenance culture: the nigerian situation," nigerian journal of engineering management, vol. 1, pp. 38-43, 2000. [10] h. e. opara and f. i. uche, "statistical analysis of the level of awareness and implementation of quality control checklist indices in the nigeria construction industry," international journal of engineering science invention, vol. 8, pp. 59-69, 2019. [11] h. e. opara, "assessment of awareness and compliance to government regulation policy aspect on quality control of building projects in the nigerian construction industry," international journal of research in engineering and science, vol. 8, pp. 08-16 8, 2020. [12] d. rodriguez, g. waite, and t. wolfe, "the global corruption report 2005." retrieved from: http://www.transparency.org/publications/gcr/download. [accessed april 7, 2011], 2005. [13] p. bowen, a. akintoye, r. pearl, and p. j. edwards, "ethical behaviour in the south african construction industry," construction management and economics, vol. 25, pp. 631-648, 2007.available at: https://doi.org/10.1080/01446190701225707. [14] s. rose-ackerman, "briefing: risks of corruption in government infrastructure projects," in proceedings of the institution of civil engineers municipal engineer 161 september 2008, 2008, pp. 149–150. [15] b. sichombo, m. muya, w. shakantu, and c. kaliba, "the need for technical auditing in the zambian construction industry," international journal of project management, vol. 27, pp. 821-832, 2009.available at: https://doi.org/10.1016/j.ijproman.2009.02.001. [16] b. wasserman, ethics and practice of architecture. new york: mcgraw-hill, 2000. [17] o. ameh and k. odusami, "professionals’ ambivalence toward ethics in the nigerian construction industry," journal of professional issues in engineering education and practice, vol. 136, pp. 9-16, 2010.available at: https://doi.org/10.1061/(asce)10523928(2010)136:1(9). [18] f. m. andrews, j. n. morgan, j. a. sonquist, and l. klem, multiple classification analysis, 2nd ed. ann arbor, michigan: institute for social research. the university of michigan, 1973. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://www.transparency.org/publications/gcr/download asian review of environmental and earth sciences issn: 2313-8173 vol. 1, no. 2, 43-50, 2014 http://www.asianonlinejournals.com/index.php/arees 43 estimation of hourly photo syntheticallyactive radiation (par) from hourly global solar radiation (gsr) in jos, nigeria anjorin, o.f. 1 --utah, e.u. 2 --likita , m.s. 3 1 department of science laboratory technology, university of jos. plateau state, nigeria 2 department of physics, university of uyo, uyo, akwa ibom state, nigeria 3 federal college of forestry mechanization, afaka, kaduna state, nigeria abstract this work is licensed under a creative commons attribution 3.0 license asian online journal publishing group 1. introduction solar radiation is the principal energy source for physical, biological and chemical processes, such as, snow melt, plant photosynthesis, evapotranspiration, crop growth and is also a variable needed for biophysical models to evaluate risk of forest fires, hydrological simulation models and mathematical models of natural processes [1]. jun, et al. [2] identified that the spectral portion of the solar spectrum that is used by plant biochemical processes in photosynthesis (light energy conversion to biomass) extends from 400 to 700 nm. this portion of the solar spectrum is called the photo syntheticallyactive radiation (par). photo synthetically-active radiation (par) is a necessary input in applications dealing with plant physiology, biomass production and natural illumination in greenhouses. unfortunately, in africa and the larger part of the world, a routine network for the measurement of photo synthetically-active radiation (par) is not yet established and it is often calculated as a constant ratio of the broadband solar radiation. par can be measured basically by two methods; one is to measure these values directly with instruments [3], and the other is to estimate them from other data [4, 5]. these are respectively referred to as direct method and indirect method. the direct method is not too commonly adopted in tropical region of africa due to its reliability problems for various reasons such as maintenance, instrument type, information on calibration, local environment, and data recording, hence the common application of indirect method. jun, et al. [2] further categorized the indirect method into two categories: satellite-based methods [6, 7] and site-based methods [8]. a satellite-based method uses remote sensing signals to retrieve information on the atmosphere, applies the retrieve [9].these parameters are used to drive an irradiative transfer model (or search a lookup table based on the irradiative transfer model), and eventually obtains par estimates at earth’s surface. a site-based method, on the other hand, takes routine meteorological data collected at weather stations as inputs to estimate par values. some schemes of this type are based on empirical relationships between the global solar radiation (gsr) and the par that are constructed in this work, an hourly model was used in estimating the values of photo-synthetically active radiation (par); a parameter closely related to plant growth in jos, nigeria (latitude 9 0 57’ n, longitude 8 0 53’e ) and altitude 1153m asl.) from hourly global solar radiation rs and to predict its hourly (par) daily seasonal trend. for this purpose, three years (2003, 2004 and 2005) data recorded using gunn-bellani radiation integrator at the weather observatory station of geography and planning department of the university of jos was used. the trend of variation of the mean hourly par pq shows that the maximum was obtained at 12.00p.m. pq for the raining season months of june, july and august for year 2003 are respectively 3.176 emj -1 , 2.900 emj -1 and 2.960 emj -1 while that of the dry season months of november, december and january for the same year are respectively 3.871emj -1 , 3.997 emj -1 and 3.655emj -1 . also, there exists seasonal variation in the average predicted value of the hourly global par; two maxima occurredmajor at february and march and the minor at november and december. the trend of variation of hourly qp/rs (μej -1 ) for the year 2003, 2004, and 2005 with local time shows maximum values at noon for the months considered. the ratio is lower and more variable in wet season than in dry season, and is usually higher at noon. keywords: global solar radiation, photo syntheticallyactive radiation, second kt model. http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2014, 1(2): 43-50 44 according to certain meteorological variables (e.g., near-surface air pressure, temperature, or humidity) [10, 11]. in this paper, an empirical model developed by alados, et al. [12] and applied in southeastern spain is used in estimating the values of photo synthetically-active radiation, qp for jos, a town in the northcentral zone of nigeria. this model is used in this work because at its development, its goal was to provide a model that is transferable to those locations where broad band solar radiation and appropriate meteorological parameters are routinely measured. this paper aims at obtaining an hourly baseline data of the values of par (qp) and its ratio to global (broadband) solar radiation (rs) for jos. also the daily seasonal characteristics of qp in different integration intervals, daily and hourly values are described. 2. geography of the site nigeria is a tropical country in west africa. jos, the town in which this project is carried out is the plateau state capital. this state is situated in the middle belt of nigeria. its coordinates are: latitude; 09 0 57n longitude; 08 0 53e and altitude; 1153m above sea level. jos is located in the transition zone between deciduous forest of the south and the savannah of the north. the monthly average temperature is almost uniform through out the year with its mean average value for 2003, 2004 and 2005 being 24.5 0 c. for 2003, 2004 and 2005 respectively, the total annual rainfalls are 1038.6mm, 1308.4mm and 1025.6mm. the prevailing winds in nigeria, and of course, jos are the south-westerly (sw) and northeasterly (ne) trade winds. the sw wind blows from the atlantic and brings rain to the west african coast, including nigeria from about april to octoberthis is the raining season period. the ne wind, a very dry wind, blows across the country between november and march bringing the harmattan dust with itthis is the dry season period. the project site is on a flat platform at the observatory station of geography and planning department, university of jos. in this site, the instruments for measuring solar radiation are the radiometer and gunnbellani radiation integrator. the observatory provides maximum exposure to the instrument sensors without much obstacle to incoming radiation. 3. method in this paper, a site-based method is adopted in which routine meteorological data were collected at the observatory station of geography and planning department of university of jos as inputs to estimate par values for the period of three years (2003, 2004 and 2005). the data of gsr obtained were in milliliters. these were converted to mjm -2 day -1 by using the calibration equation. 1ml= 1.26x 10 6 jm -2 of gunnbellani (gb) [13]. (1) the average values are tabulated in table 1 table-1. the data of average monthly global solar radiation ml and their conversion in mjm-2 day-1 4. method of prediction the monthly averages of daily global solar insolation data were obtained from the observatory unit of geography and planning department of university of jos. these data were then reduced to the daily average hourly clearness index (kt) by taking the ratio of hourly global solar insolation to the calculated hourly extra-terrestrial horizontal insolation from their respective monthly average daily values using the ratio of the hourly total to daily irradiation r t. an empirical model developed by alados, et al. [12] and applied in southeastern spain is then used in estimating the hourly values of photosyntheticallyactive radiation, qp. this empirical model otherwise known as the second kt model is expressed as:   p s q r = 1.832 – 0.191 lin kt +0.099 sin α (2) qp = hourly global “par” rs = i, hourly global solar radiation where α (degrees) is the solar altitude and is related to the zenith angle ѳz by the equation 3; [14] sin α=cos ѳz (3) the angle of incidence θz is the zenith angle of the sun: [15] cos ѳz =sinδ sinϕ + cosδ cosϕ cosω (4) 2003 2004 2005 month ml mjm2 day -1 ml mjm2 day -1 ml mjm2 day -1 jan. 16.0 20.2 19.7 24.8 12.4 15.6 feb. 19.2 24.2 19.0 23.9 17.6 22.2 mar. 19.0 23.9 19.0 23.9 16.2 20.4 april 13.1 16.5 18.7 23.6 15.6 19.7 may 18.2 22.9 13.6 17.1 11.7 14.7 june 14.0 17.6 15.3 19.7 11.2 14.1 july 12.9 16.3 14.2 18.8 8.8 11.1 aug. 12.2 16.2 12.2 15.4 7.9 10.0 sept. 15.6 19.7 15.9 20.0 11.5 14.5 oct. 17.9 22.6 17.4 21.9 15.4 19.4 nov. 17.2 21.7 17.9 22.6 15.8 19.9 dec. 17.9 22.6 18.8 23.7 15.6 19.7 asian review of environmental and earth sciences, 2014, 1(2): 43-50 45   p s q r = 1.832 – 0.191 lin kt +0.099 cos ѳz (5) this model excludes the dew point and temperature dependence. to avoid cosine response problems, solar zenith angle of less than 87 0 were used. the hourly clearness index is given as kt= 0i i , (6) where i= hourly global solar radiation measured in mjm -2 hr -1 i0= hourly extraterrestrial solar radiation measured in mjm -2 hr -1 h0 is evaluated from the equation [16]: h0= 24  isce0[( 180  )ωs(sinδsinϕ)+(cosδcosϕsinωs)] (7) where isc is the solar constant = 1367w/m 2 . eo (dimensionless) is the eccentricity correction-factor of the earth’s orbit and is given by spencer [17] as eo = 1.00011+ 0.034221cos г+ 0:00128sin г+ 0.000719cos2 г+ 0.000077sin2 г (8) the extraterrestrial hourly radiation measured in mjm -2 hr -1 can be evaluated from the equation [14]; i0=isce0 (sinδsinϕ + 0.9972cosδcosϕcosω1) (9) where isc is the solar constant measured in mjm -2 hr -1 (isc= 4.92mjm -2 hr -1 ), δ, ϕ and ω1 are the declination, latitude and hour angle respectively at the middle of an hour in degrees. the day angle г is г = 2π ( 1 365 n  ) (10) in this relation, the angles are expressed in radians. the ratio of the hourly total to daily irradiation rt is expressed by wong and chow, 2001 as tr 24   ( 1 s s s s cos cos sin cos 180         )(a +bcosω1) (11) where ω1 is the hour angle at the middle of the hour measured in degrees. this is calculated from ω1= 1 4 (number of minutes from noon). (12) ωs ,the sunrise (or sunset) hour angle is evaluated using: [18]; ωs = cos 1 (tan ø tan δ) (13) where ø = latitude of the location and δ= the solar declination. δ can be obtain from the equation 14; [19] δ= 23.45sin ( 2 ( 80) 365 n  ) (14) where n is the day of the year (n=1 on january 1st and n=365 on december 31st, february 29 th is ignored) the coefficients a and b expressed as function of ωs by collares-pereira and rabl [20] are: a =0.409+0.5016 sin (ω-60) (15) b=0.6609+0.4767 sin (ω60) (16) in terms of the hourly global solar radiation i and the monthly global solar radiation h, the expression for rt presented by collares-pereira and rabl [20] is: rt= i h = 0 0 i h (a+bcosω1) (17) hence the hourly global radiation can be obtained from the rth=i (18) where i= rs (hourly global solar radiation) (19) 5. results analysis 5.1. estimation of hourly photo synthetically active radiation (par) from hourly global solar radiation (gsr). computing the average hourly values of par (qp) from average hourly global solar radiation by using the second kt model in equation 5 gives the values of qp as presented in table 2. the tables show approximately identical seasonal variation with maximum daily value of hourly qp obtained at 12pm for january of the years 2003, 2004 and 2005 under consideration. the parameters required for estimating qp (hourly par) such as; the hourly global solar radiation, i, the hourly horizontal extraterrestrial global radiation i0, rt (which is the ratio of the hourly total to daily irradiation), the hour angle ωs, the extraterrestrial monthly horizontal global solar irradiation h0, the hourly clearness index kt, and the cosine of the zenith angle cos θz were calculated and presented in the tables 2 and 3. these values show a seasonal variation with the local time. it is clear from table 2 that qp and rs have a similar trend. the graph showing the variations with local time is shown in figure 1. each curve depicts a peak as maximum value of hourly par. from this graph, the variation of qp for 2003, 2004 and 2005 are seen to have a similar trend. asian review of environmental and earth sciences, 2014, 1(2): 43-50 46 also, the estimated values of mean hourly par, pq for 2003, 2004 and 2005 are presented in table 3. it is obvious from table 3 that higher values of pq are predicted for the dry season months and lower values for wet season months. table 4 shows a more detailed variation of the estimated pq for the dry season months of january and december and the wet season months of june and august averaged over 2003, 2004 and 2005.this also reveals higher hourly values for dry season months and lower values for wet season months. however, the maximum pq was obtained at noon around 12pm for all seasons. figure 2 shows that in 2003, 2004 and 2005, there were two maxima (major and minor) and one minimum. the major maximum occurred between february-march and the minor maximum occurred between october and november. the minimum occurred between august and september. from figure 2, the variation of qp is similar to the mean monthly global solar radiation, h in figure 4. figure 5 shows cosine of zenith angle, cos ѳz as an indispensible parameter in obtaining qp with the variation depicting similarity in behaviour with figure 1. furthermore, in an attempt to reach a deeper knowledge of the ratio of photo synthetically-active radiation to broadband solar radiation we have analysed the hourly values. the hourly pattern of the ratio photo synthetically-active photon density flux to broadband solar irradiance hourly values (qp/rs), are shown in tables 5 and 6 for the dry and wet seasons respectively. the trend of variation of diurnal hourly qp/rs (μej -1 ) for the years reveals maximum value around noon. it is found that this ratio also has seasonal and daily variations which are greater in the wet season months than in the dry season months. from these tables, the ratio is higher and more variable in wet season than in dry season, and is usually higher at noon. from figure 6, it is obvious that the lowest value occurred during the dry season months of november, december, january, february and march while the highest occurred during wet season months of may, june, july, august and september. t table-2. estimated values of hourly par for the month of january of 2003, 2004 and 2005. table-3. estimated values of the ratio of average hourly par to hourly global radiation, p s q r and average hourly par, qp 2003, 2004 and 2005. table-4. average estimated values of hourly par, qp for january, june, august and june of 2003, 2004 and 2005. local time p(january)q mjm -2 h -1 p( )q june mjm -2 h -1 p( )q august mjm -2 h -1 p( )q december mjm -2 h -1 7.00a.m 0.843 0.764 0.628 0.908 8.00a.m 2.166 1.915 1.379 2.339 9.00a.m 3.566 3.128 2.590 3.853 10.00a.m 4.770 4.171 3.458 5.156 11.00a.m 5.614 4.899 4.065 6.091 12.00p.m 5.898 5.145 4.268 6.374 1.00p.m 5.614 4.899 4.065 6.091 2.00p.m 4.770 4.171 3.458 5.156 3.00p.m 3.566 3.128 2.590 3.853 4.00p.m 2.166 1.915 1.379 2.339 5.00p.m 0.843 0.764 0.628 0.908 asian review of environmental and earth sciences, 2014, 1(2): 43-50 47 table-5. estimated values of the ratio of hourly par to hourly global radiation for january, february and march of 2003, 2004 and 2005. qp/rs 2003 (μe j -1 ) qp/rs 2004 (μe j -1 ) qp/rs 2005 (μe j -1 ) jan feb mar jan feb mar jan feb mar 7.00a.m 1.937 1.922 1.940 1.900 1.924 1.940 1.987 1.938 1.970 8.00a.m 1.960 1.945 1.964 1.920 1.947 1.964 2.009 1.961 1.994 9.00a.m 1.978 1.964 1.984 1.940 1.967 1.984 2.028 1.981 2.014 10.00a.m 1.993 1.979 1.999 1.953 1.982 1.999 2.042 1.996 2.030 11.00a.m 2.002 1.989 2.009 1.962 1.991 2.009 2.051 1.989 2.039 12.00p.m 2.005 1.992 2.012 1.965 1.994 2.012 2.054 2.009 2.043 1.00p.m 2.002 1.989 2.009 1.962 1.991 2.009 2.051 1.989 2.039 2.00p.m 1.993 1.979 1.999 1.953 1.982 1.999 2.042 1.996 2.030 3.00p.m 1.978 1.964 1.984 1.940 1.967 1.984 2.028 1.981 2.014 4.00p.m 1.960 1.945 1.964 1.920 1.947 1.964 2.009 1.961 1.994 5.00p.m 1.937 1.922 1.160 1.900 1.924 1.940 1.987 1.938 1.970 table-6. estimated values of the ratio of hourly par to hourly global radiation for july, august and september of 2003, 2004 and 2005. qp/rs 2003 (μe j -1 ) qp/rs 2004 (μe j -1 ) qp/rs 2005 (μe j -1 ) july aug sept july aug sept july aug sept 7.00a.m 2.019 2.016 1.978 1.990 2.026 1.975 2.092 2.108 2.036 8.00a.m 2.040 2.040 2.001 2.013 2.049 1.999 2.114 2.131 2.060 9.00a.m 2.059 2.059 2.020 2.032 2.068 2.019 2.133 2.151 2.080 10.00a.m 2.074 2.074 2.037 2.046 2.083 2.034 2.147 2.166 2.096 11.00a.m 2.083 2.083 2.047 2.056 2.093 2.044 2.156 2.175 2.105 12.00p.m 2.086 2.085 2.050 2.059 2.095 2.047 2.159 2.177 2.109 1.00p.m 2.083 2.083 2.047 2.056 2.093 2.044 2.156 2.175 2.105 2.00p.m 2.074 2.074 2.037 2.046 2.083 2.034 2.147 2.166 2.096 3.00p.m 2.059 2.059 2.020 2.032 2.068 2.019 2.133 2.151 2.080 4.00p.m 2.040 2.040 2.001 2.013 2.049 1.999 2.114 2.131 2.060 5.00p.m 2.019 2.016 1.978 1.990 2.026 1.975 2.092 2.108 2.036 table-7. ratio of par photon irradiation to global solar irradiation on monthly, annual and seasonal groupings [21]. fig-1. variation of hourly par with local time for january of 2003, 2004 and 2005. 0 1 2 3 4 5 6 7 8 local time pq period fp(=∑( par/h)/n(emj -1 ) standard deviation energy ratio january 1993 1.92 0.036 0.42 february 1993 2.06 0.040 0.45 march 1993 2.10 0.065 0.46 april 1993 2.14 0.032 0.47 may 1993 2.15 0.029 0.47 june 1993 2.14 0.026 0.47 july 1993 2.11 0.029 0.46 august 1993 2.09 0.036 0.46 september 1992 2.11 0.043 0.46 october 1992 2.13 0.022 0.47 november 1992 2.06 0.077 0.45 december 1992 1.96 0.043 0.43 year 2.08 0.040 0.46 q2005 q2003 q2004 asian review of environmental and earth sciences, 2014, 1(2): 43-50 48 figure-2. variation of average monthly par ( pq ) for 2003, 2004 and 2005. figure-3. variation of daily hourly extraterrestrial solar radiation, i0 and daily hourly global solar radiation, i with local time. figure-4. variation of monthly extraterrestrial solar radiation, h0 and measured monthly global solar radiation, h . 0 2 4 6 8 10 12 14 q p month i io 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 i o m j /m 2 /h r, i m j/ m 2 / h r time of day (gmt +1) i io 0 5 10 15 20 25 30 35 40 h ,h o month h h0 qp 2005 qp 2004 qp 2003 h0 h asian review of environmental and earth sciences, 2014, 1(2): 43-50 49 figure-5. variation of estimated par, qp for december 2003, 2004 and 2005 with cosine of zenith angle, cos ѳz fig-6. variation of mean monthly ratio of hourly par, qp to hourly global solar radiation, rs. 6. discussion photo-synthetically active radiation (par) is the amount of light available for photosynthesis, which is light in the 400 to 700 nanometer wavelength range. par changes seasonally and varies depending on the latitude and time of day. pq is low for the wet and raining season months as compared to the months of dry and harmattan season. for example, pq for the raining season months of june, july and august for year 2003 are respectively 3.176 emj -1 , 2.900 emj -1 and 2.960 emj -1 while that of the dry season months of november, december and january for the same year are respectively 3.871emj -1 , 3.997 emj -1 and 3.655emj -1 . it is obvious from these results that the pq is higher during the dry season months of the year. this could be attributed to sky clearness and low cloudiness. the results in table 2 show that high values of pq are predicted for the months with lower atmospheric cloudiness and much reduced harmattan dust. this occurs in february, march, may and november. the months of december and january in the harmattan have lower values of pq compare to other dry season months due to high dust concentration from harmattan and high scattering aerosols in the atmosphere due to bush burning. a careful analysis of table 2 reveals that the dry season months have mean hourly qp/rs (μej1 ) of 1.900 qp/rs (μej1 ) while the wet season months have mean hourly qp/rs (μej1 ) of 2.000 qp/rs (μej1 ). also the tables show the annual pattern of the daily monthly means of the ratio of photo synthetically-active radiation to broadband solar irradiation, qp/rs, suggests the existence of a seasonal dependence of this term. in this sense we found higher values associated with raining season months and lower values from november to march. water vapour is important because of its absorption effects. this absorption takes place in the infra-red region of the spectrum and will therefore decrease the hourly global solar radiation, rs to a much greater extent than qp. on the other hand, scattering by aerosols that have enhanced atmospheric water vapour content acts primarily in the visible region and will affect the hourly global photo syntheticallyactive radiation, qp, more than the hourly global (broadband) solar radiation, rs. also, in january and december, it could be observed that the atmosphere is very hazy with harmattan dust coming into the town from the sahara desert and aerosols due to high level of bush burning, hence the low predicted value of hourly mean qp/rs . it is to be noted that harmattan dust is known to have no waveband attenuation of the global solar radiation which is evident in the near whitish sky always prevalent during these months [21]. in march, the dust arising from harmattan clears off paving way for the onset of rainy season while in november, the dry season is about to set in. hence february and november are transition months for the mean value of the ratio 0 1 2 3 4 5 6 7 8 0.165 0.383 0.571 0.714 0.805 0.835 0.805 0.714 0.571 0.383 0.165 q 2 0 0 3 , q 2 0 0 4 , q 2 0 0 5 cos ѳz q1 q2 q3 2003 2004 2005 1.8 1.85 1.9 1.95 2 2.05 2.1 2.15 2.2 month q/i 03 q/i 04 q/i 05 p s q r asian review of environmental and earth sciences, 2014, 1(2): 43-50 50 of hourly par to hourly global solar radiation. however, the effects are not always so noticeable on a daily basis. however, during the raining season the moisture content of the atmosphere affect the results. furthermore, from figure 4, it is clear that that the monthly variation of global extraterrestrial solar radiation, h0 does not follow a fairly periodic pattern as the monthly global solar radiation, h. this is due to the fact that the calculated extra-terrestrial horizontal insolation per day at a given place, which is the insolation on a horizontal surface, is without any atmospheric effects. it can be seen from equation (7) that the extra-terrestrial horizontal insolation is a function of latitude and the day of year only. hence, it can be calculated for any location for any given day. however, the calculated insolation does not take any atmospheric effects into account. according to wong and chow [14], the clearness index, kt gives a measure of the atmospheric effects at a place on the insolation which is the measure of the climatic condition at a geographical location. the independent set of data obtained from the second kt model can be compared with the data generated by udo and aro [21] from some linear regression equations. table 7 presents the result by udo and aro [21]. it is clear that the values of par h given in this table are comparable to the values of p s q r obtained in this work as listed in table 2. hence the values of the mean ratio of hourly photo syntheticallyactive radiation (par) to the hourly global (broadband) solar radiation(rs) predicted by the second kt model are in close agreement with those predicted by udo and aro [21]. 7. conclusion the analyses of data of photo synthetically-active radiation and broadband solar radiation registered from january 2003 to december 2005 in jos, northcentral nigeria have showed the seasonal dependence of the ratio of photo synthetically-active radiation to broadband solar radiation. the higher values are for the raining season, while in the dry season are lower and more variable. the hourly values of qp for this period show that; the higher values were obtained during the dry season months of december, january, february, march and april, while the lower values occurred during the raining season months of june, july, august, september and october. however, the hourly pattern of the ratio photo synthetically-active photon density flux to broadband solar irradiance hourly values (qp/rs) for these periods show higher values around noon for all seasons. references [1] f. meza and e. varas, "estimation of mean monthly solar global radiation as a function of temperature," agric for meteorol., vol. 100, pp. 231–41, 2000. [2] q. jun, y. kun, l. shunlin, and t. wenjun, "estimation of daily mean photosynthetically active radiation under all-sky conditions based on relative sunshine data," journal of applied meteorology and climatology, vol. 51, pp. 150-160, 2011. [3] j. ross and m. sulev, "sources of errors in measurements of par," agric. for. meteor., vol. 100, pp. 103–125, 2000. [4] c. gueymard, "a twoband model for the calculation of illuminance and photosynthetically active radiation at the earth’s surface," solar energy, vol. 43, pp. 253-265, 1989b. [5] r. t. pinker and i. laszlo, "global distribution of photosynthetically-active radiation as observed from satellites," j. climate., vol. 5, pp. 56-65, 1992. [6] s. liang, t. zheng, r. liu, h. fang, s. c. tsay, and s. running, "estimation of incident photosynthetically active radiation from moderate resolution imaging spectrometer data," j. geophys. res., vol. 111, p. d15208, 2006. [7] t. zheng, s. liang, and k. wang, "estimation of incident photosynthetically active radiation from goes visible imagery," j. appl. meteor. climatol., vol. 47, pp. 853–868, 2008. [8] l. alados-arboledas, f. j. olmo, i. alados, and m. perez, "parametric models to estimate photosynthetically active radiation in spain," agric. for. meteor., vol. 101, pp. 187–201, 2000. [9] c. gueymard, "an atmospheric transmittance model for calculation of the clear sky beam, diffuse and global photosyn-thetically active radiation," agricultural and forest meteorology, vol. 45, pp. 215-229, 1989a. [10] j. f. escobedo, e. n. gomes, a. p. oliveira, and j. soares, "modeling hourly and daily fractions of uv, par and nir to global solar radiation under various sky conditions at botucatu, brazil," appl. energy., vol. 86, pp. 299–309, 2009. [11] c. p. f. s. jacovides, d. n. tymvios, k. m. asimakopoulos, m. theofilou, and s. pashiardes, "global photosynthetically active radiation and its relationship with global solar radiation in the eastern mediterranean basin," theor. appl. climatol., vol. 74, pp. 227–233, 2003. [12] i. alados, i. foyo-moreno, and l. alados-arboledas, "photosynthetically active radiation: measurements and modelling," agric. for. meteorol., vol. 78, pp. 121–131, 1996. [13] j. o. ojosu, "the iso-radiation map for nigeria," solar wind technol., vol. 7, pp. 563-575, 1990. [14] l. t. wong and w. k. chow, "solar radiation model," applied energy, vol. 69, pp. 191–224, 2001. [15] s. shyam, r. chandel, and k. aggarwal, "estimation of hourly solar radiation on horizontal and inclined surfaces in western himalayas," smart grid and renewable energy, vol. 2, pp. 45-55, 2011. [16] m. iqbal, an introduction to solar radiation. new york: academic press, 1983. [17] j. spencer, "acomparis on of methods for estimating hourly diffuse solar-radiation from global solar-radiation," solar energy, vol. 29, pp. 19–32, 1982. [18] s. o. udo and t. o. aro, "new empirical relations for determining global par for measurements of global solar relations, infrared radiation or sunshine duration," int. j. climatol., vol. 20, pp. 1265 – 1274, 2000. [19] k. ravinder and l. umanand, "estimation of global radiation using clearness index model for sizing photovoltaic system," renewable energy, vol. 30, pp. 2221–2233, 2005. [20] m. collares-pereira and a. rabl, "the average distribution of solar radiation-correlations between diffuse and hemispherical and between daily and hourly insolation values," solar energy, vol. 22, pp. 155–64, 1979. [21] s. o. udo and t. o. aro, "global par related to global solar radiation for central nigeria," journal of agricultural and forest meteorology, vol. 97, pp. 21-31, 1999. views and opinions expressed in this article are the views and opinions of the authors, asian review of environmental and earth sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content. 1 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 1-9, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.1.9 © 2021 by the authors; licensee asian online journal publishing group assessment of public-private-participation of solid waste management: a case study warri, nigeria igiekhume m. j.1 momoh e.o.2 jubril a. al-amin3 okpugwo e.4 erayanmen r.i5 thomas b.6 ( corresponding author) 1,2,5department of urban and regional planning, auchi polytechnic, auchi, nigeria. 3department of electrical & electronic engineering, auchi polytechnic, auchi, nigeria. 4department of surveying & geoinformatics, auchi polytechnic, auchi, nigeria. 6department of civil engineering, auchi polytechnic, auchi, nigeria. abstract the menace of indiscriminately disposed heaps of refuse in most urban centers in nigeria is a confirmation of the inability of the government to cope with the ills associated with rapid population growth rate and urbanization. this study assessed the participation of the private sector in the management and recycling of solid wastes as they together with the public sector strive to attain healthy and neat cities. the actor network theory (ant) was used as a framework to illustrate the interrelationship, interdependence and co-existence of the different participants in the management of solid waste. this co-existence was revealed to generate several challenges especially for the major actors such as that of the preference of informal private waste collectors to the registered contractors assigned by the government to their residential areas and the hindrances posed by community youth on private sector participant (psp). however, from the study it was revealed that the introduction of private sector participant was not enough to check the problems associated with solid waste management. rather, a holistic approach where all actors, whether householders, formal or informal waste collector, scrap collectors, ngos or cbos should be considered by the government in the policy formulation and implementation in sustainable solid waste management practices. keywords: solid waste, management, recycling, participation, psp, ant, policy. citation | igiekhume m. j.; momoh e.o.; jubril a. al-amin; okpugwo e.; erayanmen r.i; thomas b. (2021). assessment of public-private-participation of solid waste management: a case study warri, nigeria. asian review of environmental and earth sciences, 8(1): 1-9. history: received: 12 january 2021 revised: 8 february 2021 accepted: 25 february 2021 published: 10 march 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 2 2. materials and methods ...................................................................................................................................................................... 2 3. results and discussion ...................................................................................................................................................................... 4 4. conclusion ............................................................................................................................................................................................ 7 references ................................................................................................................................................................................................. 7 https://www.asianonlinejournals.com/index.php/arees/article/view/2718 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2021.81.1.9&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2021, 8(1): 1-9 2 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study assessed the participation of the private sector in the management and recycling of solid wastes as they together with the public sector strive to attain healthy and neat cities. 1. introduction wastes are inevitable products of productive and domestic activities. they are unwanted or unusable materials, substances, by-products or left over that have been discarded for lack of use or less importance. waste in general terms can be liquid or solid in nature and can be hazardous to man and his environment if not well managed. onu, et al. [1] describe solid waste management as an application of techniques that ensures the orderly execution and disposal of solid waste. globally, solid waste management has become an issue because the rate of generation of solid waste far outweighs its management. this can be attributed partly to high population which was projected by united nations to reach over eight billion by 2030 [2]. the world is undergoing the largest wave of urban growth in history with more than half of the world’s population living in towns and cities. this number has been projected to be about 5 billion by 2030 with most of these cities unfolding in africa and asia [3]. urbanization directly contributes to waste generation; as urbanization increases, solid waste generation also increases. the global solid waste generation by urban residents has been estimated to have risen from 680 million tons per year to more than 1.3 million per year, and is expected to rise to 2.2 billion tons by 2025 [4]. in addition, the lack of interest of individuals, organizations and the government in the issue of waste management has resulted in its adverse effects on the physical and social environment of man.in general terms, waste as an issue should not be treated independently from some other urbanization problems like slum, overcrowding, traffic congestion, pollution etc. since any form of solution to them is directed towards creating an aesthetically healthy environment. in developing countries, the problems associated with waste management demand a radical approach to addressing them. until recently, in most these countries, waste management had been the responsibility of the government financed by revenue. in africa for example, the public sector took monopoly of providing solid waste management in urban centers, and this has largely been blamed for the mess in the management of waste evident in most countries of the continent. the public sector was reported to be constrained owing to lack of managerial and technical capacity, cumbersome procurement procedures and inadequate financial resources [5]. according to opara [6] the outcome is the indiscriminate refuse dump featured in most african towns and cities. the fact that successive governments in nigeria have had to contend at one time or the other with the problem of huge mountains of refuse disposed in conspicuous locations in some cities is a clear indication that an appropriate solution is yet to be proffered odewumi [7]. filani and abunere [8] stated that there had been a long frustrating search for an appropriate method of waste disposal. hence, akiyode and sojinu [9] added that, the government began to review the approach of private sector participation (psp) for better service delivery in waste management. 2. materials and methods 2.1. study area warri metropolis , warri south local government area is located in delta state, delta south senatorial district, south-south nigeria, with co-ordinates 5031i n and 5045i e and occupies an area of about 633km2. its topography is flat and can be described as a lowland region characterized by natural vegetation of rainforest, with swampy forest and water bodies in some areas. with its tropical equatorial climate, the mean annual temperature is 32.80c and annual rainfall of about 2673.8mm; it is marked with two distinct seasons: the rainy and dry seasons. warri is situated on the coastal part of the delta region of nigeria and as a result has rich alluvium deposits in its soil and therefore is endowed with crude oil on and off-shore. the growth of the city can be traced to the 15th century when the portuguese arrived nigeria, it also served as the colonial capital of the then warri province, under the colony and protectorate of southern nigeria [10]. in the 19th century, warri was center for trade of palm oil, rubber, palm products, cocoa, groundnut, hides and skin (http:www.greatestcities.com/africa/nigeria/warricity_html.) owing to its port activities along the coast of the warri river. the exploration crude oil in the area in later part of the 20th century made it one of the hubs of petroleum activities and business in southern nigeria and has a population of over 311,970 people according to 2006 national census. it shares boundary with ughelli north, sapele, okpe, udu and uvwie local government areas, most of which have been integrated to the large cosmopolitan warri. figure 1 shows map of nigeria indicating delta state. 2.2. research design the methodology of this study therefore, is patterned to provide answers to the several research questions that pondered the researcher. to do this end, data of various forms were collected from the selected population in the study area by means of well-structured questionnaire, and some brought to the fore through field observation and face to face interviews. however, these data would be presented and analyzed using simple descriptive statistical tools as well as the chi-square (x2) to test the stated hypothesis, so that an inference can be drawn from some information gathered. the conclusion reached from the study would help the researcher assess the participation of private and public sector in solid waste management in warri metropolis with a view to evolving policy response capable of enhancing waste management efficiency in the area. asian review of environmental and earth sciences, 2021, 8(1): 1-9 3 © 2021 by the authors; licensee asian online journal publishing group figure-1. map of nigeria showing delta state. source: ministry of land and survey, asaba, delta state. figure-2. map of delta state showing warri south l.g.a. source: ministry of land and survey, asaba, delta state. 2.3. population of study the population of this study is a sample of the total population of warri south local government area. applying the population growth rate of 2.5% of nigeria according world population prospectus, 2015, and the 2006 national census, where the population of warri was recorded as 311,970, this research deemed it necessary to project the population of the area to be 409,332 as at the time of the study from equation 1: p1= p0 (1+r)n [1] where: p1 = projected population (year 2017). p0 = population of base year (i.e. 311,970 according to 2006 national census). r = population growth rate (2.5% for nigeria according to united nations department of economic and social affairs population division [2] n = time interval between p1 and p0 (p1p0 (11 years). it is in the light of the above that the study area would be divided into zones within which data would be collected from sample population for the study. 2.4. method of data collection 2.4.1. types of instrument for data collection the following were the instruments used for collecting data: questionnaire. asian review of environmental and earth sciences, 2021, 8(1): 1-9 4 © 2021 by the authors; licensee asian online journal publishing group face to face interview. participant’s observation. questionnaire: this was used to retrieve social-economic data. the questions consisted of open and closed type. the respondents were thus given some degree of liberty self-expression through open responses. face to face interview: oral interviews were conducted with some respondents, some staff of the department of environment, warri south local government council, warri, some the registered solid waste collectors’ company as well as some informal participants in the solid waste management industry. participants’ observation: during the study, the researcher worked in the midst of the inhabitants and therefore from their surroundings, was able to collect data by observation. 2.4.2. method of administering data collection instruments at the time of this research, the study area had 10 political units (wards) as shown below. however, using the multistage sampling technique, the area was delineated into strata which represented the different ward within which the questionnaires were equally distributed and randomly administered by the researcher. on the whole, two hundred questionnaire were administered with twenty (20) within each ward and from these, data was drawn. ward 1 – essi area. ward 2 – pessu area. ward 3 – ogunu area. ward 4 – okumagba area. ward 5 – bowen area. ward 6 – ekurede area. ward 7 – okere area. ward 8 – iyara area. ward 9 – ugbuwangwe area. ward 10 – mac demott area. 2.5. method of data presentation and analysis for the purpose of clarity, data were properly checked and coded for completeness and accuracy. the responses were grouped before coding and thereafter, both descriptive and inferential statistics were used in data presentation. 2.5.1. descriptive method of data presentation for ease of understanding, descriptive statistics used include simple percentages, bar graphs and pie charts. 2.5.2. inferential method of data analysis having used multistage sampling technique to draw data from the population, chi-square(x2), a nonparametric inferential statistical tool which is a non-directional (two-tailed test) is used to test the set hypothesis, because it can only indicate relationship but not with direction. equation 2 is applied to determine the chi-square values: x2 = [2] 2.5.3. hypotheses testing technique the statistical technique used to test the hypothesis is chisquare (x2) since it is a non-parametric statistical tool used for nominal or ordinal data as is the case of this study. however, the t-test is used to test the level of significance the relationship of the selected samples from the population in relation to the hypothesis. 3. results and discussion from the study, it was revealed that there were unsightly heaps of refuse in some areas of warri metropolis; some of these unsightly public refuse dumps were seen in some drains, canals, vacant plots, uncompleted buildings, street corners and pavements. these refuse dumps have contributed to the reduction the aesthetic quality of some areas in the urban center of warri. the study therefore shows that the introduction of private sector participation in solid waste management has not totally checked the problem of irregular waste disposal in the area. this is because the challenges faced by both the public and private sectors in the management of solid waste are enormous. with regard to environmental sustainability, the actors involved in the management of solid waste in warri were not actively involved in any form activity that could help to reduce the quantity or quality of household waste disposed into the environment such as that prescribed by the 3r’s of solid waste management, re-duce, re-use and re-cycler or the zero waste theory. however, all actors whether the government, private formal, private informal or the householders were only interested in disposing the solid waste generated and generating some revenue from it. the resultant effect is that, self disposal and private informal (wheelbarrow waste collectors) methods which do not have approved dumpsite therefore contribute to environmental degradation through indiscriminate refuse disposal and the consequent depletion of the ecosystem over time. the government and the registered contractors (private formal) are not left out of this atrocity because they only collect and dispose refuse at one approved site or another with the former not having any concrete policy in place to manage private and government dump sites, refuse being constantly burnt or left to cause flooding in adjoining residential areas. asian review of environmental and earth sciences, 2021, 8(1): 1-9 5 © 2021 by the authors; licensee asian online journal publishing group 3.1. sample population on the whole, 200 questionnaires were administered but 182 respondents were able to adequately provide sufficient information needed for the study. the data retrieved, presented and analyzed was therefore based on 182 respondents. 3.2. socioeconomic characteristics of the respondents of the total respondents, 42% were males and 58% were females with 60% of the total respondents married. also over 60% of them were above 30 years of age with all of them being literate, primary school living certificate (pslc) being the least qualification and 57% graduates from higher institutions (tables 1, 2, 3 and 4). these shows that the sample population was mature and therefore provided required the information for the study. table-1. sex of respondents. sex no. % male 76 42 female 106 58 total 182 100 table-2. marital status status no. % single 66 36 married 109 60 seperated 3 2 widowed 2 1 divorced 2 1 total 182 100 table-3. age of respondence. age no. % 15-19 years 9 5 2024 years 25 14 25-29 years 25 14 30-34 years 22 12 35-39 years 27 15 40-44 years 13 7 45-49 years 2 1 50-54 years 32 17 55 years and above 27 15 total 182 100 table-4. educational qualification. qualification no. % p.s.l.c 9 5 j.s.c.e 12 7 s.s.c.e 33 18 o.n.d./n.c.e 12 6 h.n.d/b.s.c 104 57 no formal education 5 3 others 7 4 total 182 100 in terms of their occupation, 41% of them were into business, 28% were public servants but holistically, 83% of them were gainfully employed. while 59% lived in one or two room apartments, 53% resided in flats and only 6% and 3% lived in duplex and bungalows respectively. also, 28% of the sample population had 6 and above persons per households and 24% lived in apartments with above 6 families per building. see tables 5, 6, 7 and 8. this suggests that the respondents largely belong to low and middle income groups and that their economic and domestic activities highly contribute to daily generation of solid waste disposed properly or indiscriminately within the study area. table-5. occupation of respondents. occupation no. % schooling 27 15 public/civil servants 78 41 business 51 28 artisan 3 2 retired 3 2 private employee 12 7 unemployee 3 2 others 5 3 total 182 100 asian review of environmental and earth sciences, 2021, 8(1): 1-9 6 © 2021 by the authors; licensee asian online journal publishing group table-6. types of accommodation. type no. % one or two rooms 25 32 flats 97 53 duplex 11 6 semi-detached bungalow 5 3 others 10 6 total 182 100 table-7. families per building. no. of families no. % 1 24 13 2 22 12 3 31 17 4 35 19 5 24 13 6 4 2 above 6 44 24 total 182 100 table-8. no of persons per household. no. of persons no % 1 12 7 2 17 9 3 25 14 4 41 23 5 34 19 6 30 16 above 6 23 12 total 182 100 table-9. method of solid waste disposal methods no. % registered waste collectors 42 23.1 local government collectors 15 8.2 wheelbarrow collectors 73 40.1 self-disposal 52 28.6 total 182 100 from the table 9 and the chart above, 23.1% of the total respondents’ patronized registered waste collectors, local government waste collectors served only 15% of them, as much as 40.1% patronized wheelbarrow collectors while 28.6% resorted to selfdisposal. this study revealed that the choices of the patronage of solid waste collectors by the residents are linked to the satisfaction derived by them from the services rendered and their charges. a total of 49% of the respondents were very satisfied and satisfied with their method of refuse disposal while only 12% were not satisfied at all. from some of their responses, some of the respondents complained that some refuse collectors were not regular and that some of their charges were too high. table 10 shows the effectiveness in the participation of refuse collectors whether public, private formal or informal. table-10. effectiveness in participation of waste disposal agents. regular /effective irregular/ adequate irregular/ poor agent no. % no. % no. % no % total %total registered private 25 13.7 11 6.1 6 3.3 42 23.1 local govt. 5 2.74 5 2.74 5 2.74 15 8.2 wheel barrow 48 26.4 7 3.8 18 9.9 73 40.1 self-disposal 52 28.6 52 28.6 total 78 42.84 23 12.64 29 15.94 52 28.6 182 100 table-11. unsightly heaps of refuse. unsightly refuse dump in neighborhood no. % yes 75 41 no 107 59 total 182 100 table-12. refuse dump close to residence. proximity to house no. % very close 18 10 close 25 14 not too close 32 17 none 107 59 total 182 100 asian review of environmental and earth sciences, 2021, 8(1): 1-9 7 © 2021 by the authors; licensee asian online journal publishing group 3.3. indiscriminate disposal of refuse it was revealed from the study that 41% of the total respondents agreed to occasionally have unsightly heaps of refuse in their environment (see table 11). also, from table 12, 24% admitted to have indiscriminately disposed refuse very close and close to their residents, and 17% not too close to their houses. some of these unsightly public refuse dumps were seen in some locations in the study area such as drains, canals, vacant plots, uncompleted buildings, street corners and pavements. see figures 13, 14, 15 and 16. all these refuse dumps which have reduced the aesthetic quality of some areas in the urban center, warri can be attributed to the findings of the survey that as much as 28.6% of disposed per time. as prescribed by the 3r’s of solid waste management, re-duce, re-use and re-cycle, only 8% and 5% re-use and sell respectively. some sell the sorted items to chart pushers, scrap collectors or buyers figures 13 and 14 the activities of scavengers and waste pickers who collect recyclable items from refuse dump were also actively involved in solid waste management in the study area. on the other hand 2% destroy the sorted out waste, mostly to prevent re-use of the materials for re-production of fake products and 37% later dispose them. 4. conclusion this research has dealt exhaustively with the participation of public and private sector in solid waste management in warri metropolis and in the process reviewed literatures, generated and analyzed data in relation to the study, identified challenges faced by both sectors in the management of solid waste and finally initiated policy suggestions that could help to reduce the problem of indiscriminate disposal of refuse in nigerian cities thereby making our human environment a healthy and neat place to live. references [1] b. onu, t. price, s. surendran, and s. ebie, "solid waste management: a critique of nigeria's waste management policy," international journal of knowledge, culture and change management, vol. 11, pp. 373–399, 2012. [2] united nations department of economic and social affairs population division, "world population prospects: the 2015 revision, key findings and advance tables," working paper no. esa/p/wp.2412015. [3] united nations population fund (unfpa), for people, planet and prosperity: delivering a world where every pregnancy is wanted every childbirth is safe and every young person’s potential is fulfilled. new york: unfpa, 2015. [4] w. bank, "the world bank annual report. retrieved from: https://doi.org/10.1596/978-0-8213-8376-6," 2010. [5] e. o. longe, "people’s perception on household solid waste management in ojo local government area in nigeria," iran, iranian journal of environmental health science and engineering, vol. 6, pp. 209-216, 2009. [6] j. a. opara, "urban waste management in port harcourt metropols of the niger delta region in nigeria. retrieved from: http://www.businessschool.infor/...site../updated _version_of_ucn.org. [accessed 20 november 2017]," 2009. [7] s. odewumi, "appraisal of storage and collection strategies of municipal solid waste in lagos state," iosr journal of humanities and social science, vol. 10, pp. 61–67, 2013. [8] m. o. filani and s. abunere, "foreasting solid waste management for nigeria cities in adeniji e.o. and i. b bello-iman (eds)," ed, 1986, pp. 193 – 208. [9] o. o. akiyode and o. s. s. sojinu, "assessment of private sector participation (psp) in solid waste management practices in nigeria (case study of lagos state, nigeria)," presented at the journal of solid waste management & technology. 21st international conference on solid waste technology and management, philadelphia, pa usa march 26 -29, 2006, 2006. [10] p. p. ekeh, warri city: and british colonial rule in western niger delta. lagos, nigeira: urhobo historical society, 2005. table-13. the uses of household waste after sorting. no. % re-use 14 8 sell 10 5 distroy(e.g by burning, shredding) 3 2 dispose the later 67 37 do not really sort waste 88 48 total 182 100 table-14. hypothesis 1 (method of waste disposal and effectiveness in participation of waste disposal agents) regular/ effective irregular/ adequate irregular/ poor agent no. % no. % no. % total %total registered private 25 13.7 11 6.1 6 3.3 42 23.1 local govt. 5 2.74 5 2.74 5 2.74 15 8.2 wheel barrow 48 26.4 7 3.8 18 9.9 73 40.1 total 78 42.84 23 12.64 29 15.94 130 100 table-15. hypothesis 1(obsrevered/expected frquencies) regular/ effective irregular/ adequate irregular/ poor total agent no. no. no. registered private 25 (25.2) 11 (7.43) 6 (9.37) 42 local govt. 5 (9) 5 (2.65) 5 (3.35) 15 wheel barrow 48 (43.8) 7 (12.92) 18 (16.82) 73 total 78 23 29 130 http://www.businessschool.infor/...site../updated asian review of environmental and earth sciences, 2021, 8(1): 1-9 8 © 2021 by the authors; licensee asian online journal publishing group table-16. chi-square test for hypothesis 1. cell no. observed frequencies(o) expected frequencies (e) (o-e) (o-e)2 (o-e)2 e 1 25 25.2 -0.2 0.04 0.0016 2 11 7.43 3.57 12.74 1.72 3 6 9.37 -3.37 11.36 1.21 4 5 9 -4 16 1.78 5 5 2.65 2.35 5.52 2.08 6 5 3.35 1.65 2.72 1.03 7 48 43.8 4.2 17.64 0.04 8 7 12.92 -5.92 35.05 2.71 9 18 16.28 1.72 2.96 0.18 total x2 = 11.112 table-17. hypothesis 2 (method of solid waste management and indiscrimate disposal of soild waste). registered private local govt. wheel barrow selfdisposal unsighly heaps of refuse close to residence no. % no. % no % no % total %total yes 34 18.7 10 5.5 65 35.71 44 24.1 153 84.1 no 8 4.4 5 2.75 8 4.4 8 4.4 29 15.9 total 42 23.1 15 8.2 73 40.1 52 28.6 182 100 figure-3. govt. waste tipping truck 1. figure-4. govt. waste collector truck 2. figure-5. registered waste collector truck. figure-6. informal waste collector tricycle. asian review of environmental and earth sciences, 2021, 8(1): 1-9 9 © 2021 by the authors; licensee asian online journal publishing group figure-7. informal private waste collector. figure-8. informal private waste collector, okumagba avenue emebiren street. figure-9. self-disposal on a vacant plot, plaza at deco road. f figure-10. indiscriminate disposal on major road. figure-11. refuse dump in a canal (serving avenue-okere axis). figure-12. refuse dump by street corner iyesa street junction. figure-13. recyclable items collected. figure-14. scrap buyer (cart pusher). asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 41 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 41-46, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi:10.20448/journal.506.2020.71.41.46 © 2020 by the authors; licensee asian online journal publishing group construction design and sustainability in architecture bada a.o1 akharia o.o2 daodu, s.a2 dania, s.f3 ( corresponding author) 1department of urban & regional planning, auchi polytechnic, auchi, nigeria. 2,3department of architectural technology, auchi polytechnic, auchi, nigeria. 4department of building technology, auchi polytechnic, auchi, nigeria. abstract the study aims to access the implementation of sustainable housing indicators (shi) in the building design and construction in ondo state, nigeria. generally, the overall degree of incorporating shi in the building construction showed that ondo central district (ocaez) has the highest design compliance, while the awareness is unpopular in ondo north district (onaez) and ondo south district (osaez). conversely, the selection of sustainability key indicators is very important at the early design stage and this would be veritable to projecting the environmental impact, energy and air quality sustainability potency of building. this development will go a long way to integrate and improve the building design and construction and enabling sustainability in building development. keywords: sustainable housing indicator, environmental impact, sustainability, building design, ondo state. citation | bada a.o; akharia o.o; daodu, s.a; dania, s.f (2020). construction design and sustainability in architecture. asian review of environmental and earth sciences, 7(1): 41-46. history: received: 19 december 2019 revised: 24 january 2020 accepted: 27 february 2020 published: 6 april 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 42 2. methodology ..................................................................................................................................................................................... 42 3. results and discussion ................................................................................................................................................................... 43 4. conclusion ......................................................................................................................................................................................... 45 references .............................................................................................................................................................................................. 46 https://www.asianonlinejournals.com/index.php/arees/article/view/1474 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.41.46&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2020, 7(1): 41-46 42 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the study contributes to existing literature by accessing the implementation of sustainable housing indicators (shi) in the building design and construction in ondo state, nigeria. 1. introduction sustainable building design and construction is the practice of making structures and using processes that are environmentally responsible and resource efficient throughout the life cycle of a building from selecting the site to design, construction, operation, maintenance, renovation, and finally, deconstruction. the building industry is a vital element of any economy but has a significant impact on the environment [1]. sustainability is an important issue to consider in building design, for environmental design and socio-economic to integrate and develop global architectural excellence. until modern architecture conquered the world, architecture was mostly rational, functional, hence resource conserving and energy saving in the regional/local climatic context [2]. architecture exemplified the local physical appearance or a place. akadiri, et al. [1] reported that vernacular architecture, by its nature, had built-in sustainability, both physical and cultural. several important variables and indicators are considered at the onset of design phase for building analysis and sustainability projections. studies of many authors have agreed on the significance of indicators to measure and predict sustainability in architecture. the concept of sustainability includes promoting the quality of life, thus allowing people to live in a healthy environment, with improved social, economic and environmental conditions [3]. sustainable buildings should be designed and developed to take in cognizance factor to limit and mitigate greenhouse gases emission (ghg), environmental pollution such as noise, and integration of indoor and outdoor air quality and cross ventilation. john, et al. [4] reported that a number of certain objectives such as resource and energy efficiency, co2 and ghg emissions reduction, pollution prevention, mitigation of noise, improved indoor air quality, harmonization with the environment should be considered in building design for optimal sustainability. many studies have revealed that that the world population will increase by more than 45% by the mid of 21th century. the projected increase in population could be a major factor for exponential demand for shelter and housing units mostly in developing countries. the pressure of creating a sustainable housing unit for the increasing population will further complicate the environmental processes through the deforestation, consumption of huge fossil fuel and depletion of ozone layer from the building production companies. globally, the building sector is arguably one of the most resource-intensive industries [1]. a sustainable housing design involves highly simulated and technically-based approaches which allows continuous modifications and adjustment at every stage. ensuring the high quality of design is to ensure an approach based on building performance, an integrated and interdisciplinary project team working through an integrated planning and preparing a project to its best performance [5]. thus, the design process is crucial because most decisions that will determine building performance in use will be made at this stage [5]. in any architectural project, the principal intention and objective of the project has to be clearly defined. the conceptual ideal must be well studied, queried and modified to meet the expected client’s demand. during this initial phase, clients and design team share information seeking to develop the building’s concept. the architectural programming is required to define key requirements and constraints towards project quality. the study aims to measure and identify the sustainability indicators in housing design and to determine its adaptability to the architectural design and construction in ondo state, nigeria. the output of this study is aimed to allow the architect and other housing designers to accommodate environmental sustainability indicators in their housing design from the early to completion stage at affordable cost. 2. methodology housing design and development today is much different from what used to be obtainable many decades ago; these changes are mostly in the cities, developing and developed environment. however, improvement is incorporated to make housing facility be more conducive to enhance healthy living and socio-economic activities. the advancement in housing design includes introduction of integrated mechanism which could be used to mitigate the emission of ghgs, air-quality monitor and automated ventilators. to make building to be sustainable, allowance for all integrated indicators must be provided. modern movement and modernism have made a huge impact on industrial buildings, while at the same time industry has influenced the modernistic architects [2]. in order to achieve a sustainable future in the building industry, asif, et al. [6] suggest adoption of multi-disciplinary approach covering a number of features such as: energy saving, improved use of materials, material waste minimization, pollution and the greenhouse gas emissions control measure etc. having considered the importance of designing for sustainable use, a set of design-indicator data was obtained in ondo state, nigeria for this study. the sustainable housing (shi) indicators considered are as follows: i. environmental impacts include global warning, depletion of ozone layer, co2 and climatic monitors (ei). ii. energy (e). iii. life cycle cost (lcc). iv. air quality control (agc). ondo state has a total landmass area of 77,818 km2 located in southwestern nigeria. the study area is surrounded by the states of kwara and kogi on the north, edo on the east, delta on the southeast, and osun and ogun on the west and by the bight of benin of the atlantic ocean on the south. the study area comprises mangrove-swamp forest near the bight of benin, a tropical rain forest in the centre part, and wooded savannah in the north. ondo state is located at an elevation of 264 meters above sea level and lies on coordinates 7°10'0" n and 5°4'60" e in dms (degrees minutes seconds). figure 1 shows the location of southwestern region and ondo state inside the map of nigeria. construction of housing units and other infrastructural amenities are on-going in the state to meeting the growing population. many building designers have been preoccupied with style and formmaking, disregarding environmental quality and human satisfaction in and around the built environment [1]. conversely, design to promote and protect human health and well-being should be the priority of architect and other designers. the sustainable housing (shi) indicators were measured from three categorized regions (ondo asian review of environmental and earth sciences, 2020, 7(1): 41-46 43 © 2020 by the authors; licensee asian online journal publishing group central agro-ecological zone in the state [onaez], ondo south agro-ecological zone [osaez] and ondo central agro-ecological zone [ocaez]) that made up of ondo state. figure-1. map of nigeria showing location area of the study region (ondo state). source: odsma [7]. 3. results and discussion table 1 shows the results of selected sustainable housing indicator (shi) in every ecological zone of the state. in ondo central zone (ocaez), it clearly shown that there exists a great awareness of incorporation of shi into the building designs. environmental impact indicator (global warning, depletion of ozone layer, co2 and climatic monitors). table-1. level of sustainable housing indicator design. sustainable housing indicator (%) study region ei e lcc agc onaez 20.3 20.6 46.2 43.4 ocaez 38.4 55.4 61.5 66.2 osaez 15.2 13.2 10.8 15.2 source: field output, 2019. 3.1. air quality control indoor air quality (iaq) is the air quality that flows within and around building and structures. it has been a reality that iaq affects the health and well-being of the people occupying the building. poor indoor air quality has been associated with a number of ailments and diseases such as depression, suffocation, headache, assimilation and concentration problems. bruce, et al. [8] reported that indoor air quality could be affected by gases such as carbon https://en.wikipedia.org/wiki/air_quality asian review of environmental and earth sciences, 2020, 7(1): 41-46 44 © 2020 by the authors; licensee asian online journal publishing group monoxide, radon, volatile organic compounds, particulates, microbial contaminants or any mass or energy stressor that can induce adverse health conditions. in view of this, incorporation of air quality control and monitor becomes a necessity in modern housing design. the result in table 1 shows that 43.4 % and 15.2 % of the sampled modern houses in ondo north district (onaez) and ondo south district (osaez). however, ondo central district (ocaez) indicated the highest building structures of 66.2% as showed in figure 2. this observation shows there is a growing awareness to upgrade the quality of indoor air quality in the state. urbanization, class, status and education are the major factors that actually influence the installation of air quality monitors in most houses. ondo central district of the state comprises the most educated people and also houses the capital town of the state as such, the awareness in this region is extremely high. the observation from this findings, it is revealed that the people dwelling in ocaez) enjoyed better health status than the dweller from the less developed districts (onaez and osaez) which could be related to improved quality of air. indoor air pollution in developing nations is a major health hazard [9]. a major source of indoor air pollution in developing countries is the burning of biomass (e.g. wood, charcoal, dung, or crop residue) for heating and cooking [9]. figure-2. design of air quality control in building in ondo state. source: sensitivity analysis, 2019. 3.2. life cycle cost life cycle cost is a method of economic analysis directed at all costs related to constructing, operating, and maintaining a construction project over a defined period of time. the main question for a sustainable design is how to put economic optimization into the early design stages. early stages of the design processes are very critical phases to take a decision related to critical issues which are construction and operating costs, bogenstätter [10] stated that ecological and economic objectives perfectly complement each other to achieve sustainability. the result in table 1 and figure 3 shows that the ondo central district (ocaez) has the highest design for lcc in the early stages of building constructions, whereas there is a poor awareness of lcc in ondo south district (osaez). also, there is a growing of incorporating lcc design in building structures at ondo north district (onaez). pellegrini‐masini, et al. [11] investigate the total lifetime costs of three cases of energy demand reduction technologies over a 25 years’ period (2005–2030) for housing stock in the uk. woodward [12] study life cycle costing to evaluate housing affordability with the aid of a computer program. woodward [12] draw attention to the significance of energy consumption in affordable houses. figure-3. design of life cycle cost in building in ondo state. source: sensitivity analysis, 2019. asian review of environmental and earth sciences, 2020, 7(1): 41-46 45 © 2020 by the authors; licensee asian online journal publishing group figure-4. design of energy (e) for building in ondo state. source: sensitivity analysis, 2019. figure-5. design of environmental impacts (ei) for building in ondo state. source: sensitivity analysis, 2019. 3.3. energy buildings consume energy and other resources at each stage of building project from design and construction through operation and final demolition [3]. building construction consumes large volume of energy throughout the construction stages. according to lenzen and treloar [13] reported that the kind and amount of energy use during the life cycle of a building material, right from the production process to handling of building materials after its end life can, for example, affect the flow of greenhouse gases (ghgs) to the atmosphere in different ways over different periods of time. based on this, it is important to reduce the energy used mostly through the burning of fossil fuel and exploit the renewable energy mix. for that reason, the total demand for primary energy should be minimized and the share of renewable energy should be maximized while reducing the share of nonrenewable energy during the building’s life cycle [5]. it is clearly revealed that the energy (e) consumption for the ondo central district (ocaez) is the highest in the region with 54.4 % whereas in ondo north district (onaez) and ondo south district (osaez) have less consumptive rates of 20.6% and 13.2% table 1 and figure 4. the output of the energy analysis showed that the rate of urbanization is a critical factor that influence energy used in the building design and construction. however, most of the buildings in the urban centres have design provisions for space heating, space cooling, domestic hot water production and other energy consuming appliances. 3.4. environmental impacts the building life cycle is an approach to design that considers environmental impacts such as pollution, energy consumption, global warming potential-gwp, greenhouse house emission over the life of the building. these environmental impact factor could also be determined using simapro standard of impact estimator software. however, it is showed that the environmental impact is lowest at ondo south district (osaez) with 15.2% and highest at ocaez as indicated in table 1 and figure 5 respectively. conversely, this observation revealed that population density is proportional to environmental impact. and as such, the awareness of incorporating environmental impact monitors such as co2 and ghgs monitors in urban centre (ocaez) is higher than the less dwelling places. 4. conclusion the aim of this study is to determine the sustainable indicators that could be evaluated in housing design project. sustainable building is a measure to safeguard and shielding the environment from the building industrial sector. generally, there is a growing awareness on the incorporation of sustainable housing indicator such as environmental impact indicator, energy and air quality control on the housing design in ondo state with particular emphasis in ondo central district (ocaez). holistic implementation of sustainable indicator (shi) in ondo state will be useful for economic integration and development. findings have showed that there is significant relationship among shi, socio-economic and environmental performance. in order to achieve a sustainable building asian review of environmental and earth sciences, 2020, 7(1): 41-46 46 © 2020 by the authors; licensee asian online journal publishing group structure and reduce the construction cost and negative effect of building construction, all the sustainable housing indicator should be well designed and incorporated into the building. references [1] p. o. akadiri, a. ezekiel, a. chinyio, and p. o. o., "design of a sustainable building: a conceptual framework for implementing sustainability in the building sector," buildings, vol. 2, pp. 126-152, 2012. available at: https://doi.org/10.3390/buildings2020126. [2] s. yılmaz, "sustainable design in architecture," presented at the a international design conference design 2006 dubrovnik croatia, may 15 18, 2006, 2006. [3] o. ortiz, f. castells, and g. sonnemann, "sustainability in the construction industry: a review of recent developments based on lca," construction and building materials, vol. 23, pp. 28-39, 2009. available at: https://doi.org/10.1016/j.conbuildmat.2007.11.012. [4] g. john, d. clements-croome, and g. jeronimidis, "sustainable building solutions: a review of lessons from the natural world," building and environment, vol. 40, pp. 319-328, 2005. available at: https://doi.org/10.1016/j.buildenv.2004.05.011. [5] l. bragança, m. v. susana, and b. a. joana, "early stage design decisions: the way to achieve sustainable buildings at lower costs," 2014. [6] m. asif, t. muneer, and r. kelley, "life cycle assessment: a case study of a dwelling home in scotland," building and environment, vol. 42, pp. 1391-1394, 2007. available at: https://doi.org/10.1016/j.buildenv.2005.11.023. [7] odsma, "categorization of agro-ecological zones in ondo state," bulletin, vol. 5, p. 65, 2007. [8] n. bruce, r. perez-padilla, and r. albalak, "indoor air pollution in developing countries: a major environmental and public health challenge," bulletin of the world health organization, vol. 78, pp. 1078-1092, 2000. [9] e. duflo, m. greenstone, and r. hanna, "indoor air pollution, health and economic well-being," sapi en. s. surveys and perspectives integrating environment and society, vol. 3, pp. 70-75, 2008. [10] u. bogenstätter, "prediction and optimization of life-cycle costs in early design," building research & information, vol. 28, pp. 376386, 2000. available at: https://doi.org/10.1080/096132100418528. [11] g. pellegrini‐masini, g. bowles, a. d. peacock, m. ahadzi, and p. f. banfill, "whole life costing of domestic energy demand reduction technologies: householder perspectives," construction management and economics, vol. 28, pp. 217-229, 2010. available at: https://doi.org/10.1080/01446190903480027. [12] d. g. woodward, "life cycle costing—theory, information acquisition and application," international journal of project management, vol. 15, pp. 335-344, 1997. [13] m. lenzen and g. treloar, "embodied energy in buildings: wood versus concrete—reply to börjesson and gustavsson," energy policy, vol. 30, pp. 249-255, 2002. available at: https://doi.org/10.1016/s0301-4215(01)00142-2. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 70 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 70-77, 2019 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.70.77 © 2019 by the authors; licensee asian online journal publishing group groundwater quality determination for drinking purpose by using water quality index technique: a case study of gadap town, karachi, pakistan asal eghbal bakhtiari1 adnan khan2 zubaid saeed3 ayesha kanwal4 ( corresponding author) 1,2,3,4department of geology, university of karachi, karachi, pakistan. abstract present study is aimed at assessment of groundwater quality of gadap town for drinking purpose using water quality index (wqi) technique. gadap is located in the outskirt of karachi city and mainly influenced by the agriculture activities. groundwater samples (n = 22) were collected mainly from boring wells and a few through tube wells from variable depths (100-600 feet). the analytical results of water reveal occurrence of very high tds (range: 466-3810; mean: 1402) and hardness contents (range: 250-2800 mg/l). on the other hand, ph varies (range: 6.9-8.1; mean: 7.5) within who guidelines (6.5-8.5) with a few samples showing turbidity. about one third of total collected samples (n = 8) were analyzed for qualitative determination of microbial contamination which are found positive, except one sample, indicating the sewage mixing. major chemistry of groundwater is also found disturbed in terms of high content of na (mean: 219 mg/l), k (mean: 15 mg/l), ca (mean: 144 mg/l) and mg (mean: mg/l 137). similarly, anions varied in the order of cl > hco3 > so4 > no3. although some parameters show the bad quality of water but water quality index (wqi) value (16.18) indicates that the groundwater quality is suitable for drinking purpose. it is inferred from the present study that water quality is partly polluted due to anthropogenic activities mainly by sewage infiltration. keywords: groundwater, geochemistry, drinking quality, wqi, gadap town, karachi. citation | asal eghbal bakhtiari; adnan khan; zubaid saeed; ayesha kanwal (2019). groundwater quality determination for drinking purpose by using water quality index technique: a case study of gadap town, karachi, pakistan. asian review of environmental and earth sciences, 6(1): 70-77. history: received: 3 september 2019 revised: 7 october 2019 accepted: 13 november 2019 published: 30 december 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: authors are indebted to department of geology, university of karachi for providing the analytical facilities. dr. ghulam murtaza arain, laboratory incharge of pakistan council for research in water resources (pcrwr) is also thanked for analyzing the samples to determine some parameters. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 71 2. materials and methods ................................................................................................................................................................... 71 3. results and discussion ................................................................................................................................................................... 73 4. conclusion ......................................................................................................................................................................................... 77 references .............................................................................................................................................................................................. 77 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.70.77&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 https://www.asianonlinejournals.com/index.php/arees/article/view/1191 https://orcid.org/0000-0001-7889-820x https://orcid.org/0000-0001-6607-4190 https://orcid.org/0000-0002-8741-1392 https://orcid.org/0000-0002-7737-0048 asian review of environmental and earth sciences, 2019, 6(1): 70-77 71 © 2019 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this paper will augment the worth of wqi technique being used for explaining the water quality objectively. it will also add the information about groundwater behavior occurring in the suburbs of the mega city. 1. introduction groundwater is one of the imperative natural resource to drive the life cycle. it is widely used for various purposes including industry, drinking, washing and irrigation. it can only be used if available in sufficient quantity with acceptable quality [1]. hydrological cycle naturally works as a big pump which continuously transfers the water from oceans to land; mainly underground [2]. modern agricultural practices, urbanization and industrialization have created the menace of water pollution [3]. these anthropogenic activities not only alter the physicochemical characters of water bodies but also contaminate the environment. once the groundwater gets polluted it is difficult and costly to be cleaned up. hence, to identify the potential toxicants and mechanism of release from their sources is important to prevent these water resources. agricultural practices are common in areas where the fertile soil and water is available in copious amount. however, due to nutrient deficiency in agricultural soils, plenty of fertilizer or manure is used to get required crop yield. on the other hand, eutrophication, a result of high nutrient loads (mainly nitrogen and phosphorus), is considered to be the prevailing water quality problem for surface water [4]. other pollutants originating in agricultural activities include sediments, oxygen-demanding substances and pesticides. similarly, salinization is also reported as the most widespread groundwater quality problem and as having the greatest environmental and economic impacts [5]. this in turn leads to release various toxic elements into the water which ultimately contaminate the groundwater resources. this groundwater is also used by the dwellers of the agriculture-based community as main source of cooking, washing and drinking. as a result, the health and life of such community gets threatened. it is therefore important to monitor and regulate the groundwater of such areas to prevent from any catastrophe. about 60% of urban population in pakistan is using groundwater for drinking and domestic purpose without regulating the water as per world health organization (who) standards [1]. karachi is the largest city of pakistan which is blessed with several ephemeral streams and channels culminating at two main rivers namely lyari and malir which ultimately discharge to arabian sea. the land around these natural water courses is being used for agricultural activities since long. some agricultural sites are still pristine however others are rapidly transforming into the urban centers. gadap town is the agricultural periphery of karachi city which is the hub of vegetable supply to this mega city and adjoining areas. some reports on the base line data have shown the occurrence of high nitrate in the groundwater of gadap (e.g. chughtai, et al. [6]). as a result, the health of people living in gadap town is questioned. however, no detailed work has been carried out so far to address the groundwater quality and possible sources of contamination in this part of karachi city. therefore, present study is aimed at assessing the groundwater quality of gadap town using a new approach i.e. water quality index (wqi). other objective is to statistically trace out the factors responsible for influencing the chemistry of groundwater in study area. 2. materials and methods 2.1. study area gadap town is subdivision of malir district which situated in the northwestern part of karachi city figure 1. this town is also forming the provincial border between sindh and balochistan, while to the north and east are jamshoro district and the kirthar mountains. gadap town has 8 union councils with over 400 rural villages accommodating the population of about 289,564 (1998). gadap basin is influenced by the ephemeral channels occurring in the outskirt of karachi city and mainly influenced by the agriculture activities. over the last decade the gadap is transformed into semi-area urban. figure-1. location map of gadap town, karachi, (after mahboob, et al. [7]). source: this map has been taken from mahboob, et al. [7] paper which is cited in the figure caption. https://en.wikipedia.org/wiki/town https://en.wikipedia.org/wiki/karachi https://en.wikipedia.org/wiki/sindh https://en.wikipedia.org/wiki/balochistan_(pakistan) https://en.wikipedia.org/wiki/jamshoro_district https://en.wikipedia.org/wiki/kirthar_mountains asian review of environmental and earth sciences, 2019, 6(1): 70-77 72 © 2019 by the authors; licensee asian online journal publishing group 2.2. sample collection twenty-two groundwater samples were collected from boring wells at a depth range of 100-600ft. groundwater was electrically pumped for 2-3 minutes to get true samples. location of the wells was marked with the help of global positioning system (gps) on the google earth image and transformed on the map prepared by using gis technique figure 2. groundwater samples were collected in plastic bottles of 1.5-liter capacity for physico-chemical analysis. bottles were properly washed and rinsed thoroughly with distilled water and then with groundwater at sampling site. to determine nitrate concentration groundwater samples were collected in bottles of 100 ml capacity and one ml boric acid solution was injected through sterile syringe in each water sample to cease any further reaction. figure-2. sample location map of study area. 2.3. groundwater analysis all the physico-chemical tests were carried out in the laboratory of geology department, university of karachi. the ph and tds/ec of collected groundwater samples (n=22) were measured with the glass electrode ph meter (adwa ad 111) and ec meter (adwa ad 330) respectively. concentration of sodium and potassium was determined by using flame photometer (model no. jenway pfp7). sulphate content was tested by gravimetric method, while bicarbonate and chloride were estimated by argenometric titration method. the method used for the analysis of calcium and total hardness was edta titration standard method (1992). magnesium was estimated as the difference between hardness and calcium with the help of formula. groundwater samples preserved in the boric acid were analyzed to determine the nitrate concentration by cadmium reduction method (hach-8171) on spectrophotometer. 2.4. water quality index (wqi) groundwater quality index of gadap town was determined by using weighted arithmetic index method as proposed by brown, et al. [8] to evaluate the water quality status of study area. physicochemical parameters including ph, tds, major cations (na, k, ca, mg) and anions (hco3, cl, so4, no3) were used to calculate wqi of groundwater in gadap town. wqi is calculated by using following formula. wqi=∑qnwn/ ∑wn where, qn is the quality rating of nth water quality parameter. wn is the unit weight of nth water quality parameter. the quality rating qn is calculated using the equation . qn=100*[(vn – vi) / (vsvi)] where, vn is the actual amount of nth parameter present. vi is the ideal value of the parameter, vi = 0, except for ph (vi = 7). vs is the standard permissible value for the nth water quality parameter. unit weight (wn) is calculated using the formula. wn= k / vn, where, k is the constant of proportionality and it is calculated using the equation k= 1 / ∑vs= 1, 2, …, n asian review of environmental and earth sciences, 2019, 6(1): 70-77 73 © 2019 by the authors; licensee asian online journal publishing group 3. results and discussion 3.1. physical parameters the characteristics of collected groundwater samples (n = 22) have been summarized in table 1. although a few samples are slightly saline and some show yellow color but others are safe in terms of color, taste and odor table 1. the groundwater ph is slightly alkaline (mean: 7.5) with subtle variation in range (6.9-8.1) which is within the permissible range of who (6.5-8.5) for drinking. the groundwater temperature is low (mean: 28 °c) which fluctuates between 25 to 32˚c suggesting that it’s meteoric origin which has been hosted in the aquifers through surface water infiltration [9-17]. only 5 samples (10, 13, 18, 21 and 22) are found turbid table 1 which are also sewage impacted as indicated by occurrence of pathogenic bacteria table 1. turbidity in water is function of suspended load including organic particles, bacterio-plankton units, colloids, air bubbles and other non-uniformities in the water samples [18, 19]. in study area, people use to drain sewage into open pits or channels because they live in semi urban set up where lined sanitation is not yet available. as a result, organic matter and solutes are likely to infiltrate through sediments up to aquifers depths, causing high turbidity [20, 21]. sewage contamination is reported even at the depth of 500 feet in groundwater of study area. generally, the sewage contamination occurs at very shallow depth but the presence of sewage at such depths seems to be the function of sediments having good transmissivity and infiltration which is characteristic of alluvial sediments comprising silty-clay to silty-sand. it is consistent with the fact that subsurface rocks in the study area are dominated by silty sand belonging to nari formation. these fine clastics have least tendency to hold/adsorb the organic matter on their surface as compared to clays therefore the occurrence of such organic material is plausible in the study area. total dissolved solids (tds) and total hardness (th) of collected samples are found to be highly variable (466-3810 mg/l and 250 to 2800 mg/l respectively) in the groundwater of gadap town. tds content occur three times higher than the permissible limit of who (500 mg/l) for drinking water in most of the groundwater samples of study area table 1. this wide variation in tds content may attribute to geochemical process and anthropogenic activities [22] in the study area. as discussed earlier, the gadap basin is an agricultural land where organic matter in the surface soil is ubiquitous. this organic matter is prime driver of generating the organic acids which is significantly leaching the ions from soil and sediments resulting in increased specific conductance or salinity of water [23]. on the other hand, semi-arid climate has also concentrated the salts in the groundwater due to intense evaporation [24, 25]. likewise, sewage infiltration to the aquifer depth is also augmenting the salt contribution in the groundwater of gadap basin. 3.2. chemical parameters sodium (na) and potassium (k) are found to be highly variable in the study area ranging between 52.43-620 mg/l and 3.73-105 mg/l respectively. na with a mean of 219.9 mg/l is found to be the dominant cation among the solutes but only in few samples exceed the permissible limit of who (200 mg/l) set for drinking water table 2. likewise, distribution pattern of calcium (ca) is highly variable (range: 12 520 mg/l) in the collected samples table 3. similarly, the mean concentration of mg (137.83 mg/l) in the groundwater of gadap town is double the who permissible limit (50 mg/l) which spans between 12.5 to 388 mg/l table 3. this suggests the role of multiple sources for contributing this element into the aquifer of study area. on the other hand, k content is marginally high (mean: 15.9 mg/l) in some of the samples (n=6) violating the desired limit (12 mg/l) of who table 2. chloride (cl) and bicarbonate (hco3) are dominant anions followed by sulphate (so4) and nitrate (no3). chloride shows elevated concentration (mean: 597.31 mg/l) in almost all of the collected groundwater samples which is almost double the permissible limit of who (250 mg/l) for dirking water. however, so4 concentration is found to be within the permissible limit set for drinking water by who (250 mg/l) in all of the samples except 5 table 2. 3.3. ionic interrelationship statistical analysis of the collected groundwater samples shows the strong positive correlation of hardness with all physical and chemical parameters except hco3, no3 and f and the same pattern is expressed by tds table 4. strong positive correlation of tds with mg (0.6) and so4 (0.8) indicates the influence of clay minerals through water rock interaction. elevated concentration of salts (na, k, mg, cl, so4) coupled with bacterial occurrence also suggests mixing of sewage with groundwater [26]. on the other hand, very high hardness (mean = 776.7 mg/l) of these collected samples indicate dissolution of limestone and mg release from clays. 3.4. hydrofacies analysis hydrofacies reflect the effect of chemical processes occurring between minerals within the lithological framework and the groundwater [27]. for this purpose, the piper diagram is used to show the relative concentration of the major cations and anions [27, 28]. the results of groundwater analysis indicate that dominant hydrofacies occurring in the aquifers of gadap town is mg-cl (50%). asian review of environmental and earth sciences, 2019, 6(1): 70-77 74 © 2019 by the authors; licensee asian online journal publishing group table-1. physical parameter of collected samples from gadap town. s. no locality depth (ft.) color taste odor turbidity ph tds mg/l ec µs/cm temp. ˚c hardness mg/l mico. (-ve/+ve) 1 chanesar goth 360 color less normal odorless #nt 7.3 1170 150.4 28 500 +ve 2 khameso goth 350 color less normal odorless nt 7.8 533 682.9 26.7 250 +ve 3 sorafaqirsorab goth 300 color less normal odorless nt 7.4 920 1176 31.6 270 +ve 4 badambagh 500 color less normal odorless nt 7.6 1240 1562 27.1 780 +ve 5 gabol stop 400 color less saline odorless nt 7.6 1050 1382 28.5 560 -ve 6 manzor baloch hotel 600 color less saline odorless nt 7.8 836 1073 25.1 450 tnp 7 lucky farm house 350 color less normal odorless nt 8 1370 1709 28.9 700 tnp 8 bhitai farm house 330 yellow saline odorless nt 7.1 2110 2707 27.9 1300 tnp 9 bhitai farm house 100 color less normal odorless nt 7.3 690 880.6 27.5 480 tnp 10 bhitai farm house 320 color less saline odorless turbid 7.2 1630 2093 27.9 1030 tnp 11 haji khudabaksh f.h. 220 color less normal odorless nt 7.4 466 595 26.4 350 tnp 12 haji khudabaksh f. h. 400 color less normal odorless nt 7.6 532 681 30.2 500 tnp 13 dattari farm house 500 color less normal odorless turbid 7.6 970 1240 28.3 480 tnp 14 sarim farm house 340 color less saline odorless nt 7.5 740 947.8 28.1 450 tnp 15 radho goth 400 color less normal odorless nt 7.2 3390 4780 29.4 2800 tnp 16 radhojokhio goth 220 color less saline odorless nt 7.3 3810 5280 28.4 2350 tnp 17 goth rado 200 color less normal odorless nt 7.3 771 1083 30.1 700 tnp 18 m.ishaq baloch bohlari 150 yellow normal odorless turbid 7 2870 4040 30 2250 tnp 19 m.ishaq baloch bohlari 120 color less saline odorless nt 7.3 950 1484 30.1 890 tnp 20 gajan village 250 color less normal odorless nt 8.1 790 1090 28 *tnp +ve 21 radho goth 170 yellow saline odorless turbid 7.6 3210 4429 29 tnp +ve 22 haji arzi village 200 color less saline odorless turbid 8 800 1104 28 tnp +ve note: #nt = non turbid. *tnp = test not performed. asian review of environmental and earth sciences, 2019, 6(1): 70-77 75 © 2019 by the authors; licensee asian online journal publishing group table-2. chemical characteristics of collected groundwater samples. note: *bdl=below deduction level. table-3. the statistical descriptive of the collected samples in the groundwater of the gadap town. parameters min. max. mean sd depth ( ft) 100 600 308.2 130.4 ph 6.95 8.1 7.47 0.31 tds (mg/l) 466 3810 1402 1008 ec (µm/l) 150.4 5280 1826 1466 temp (◦c) 31.6 31.6 28.42 1.46 ca (mg/l) 520 520 144.63 150.48 mg (mg/l) 388 388 137.83 102.25 na (mg/l) 52.43 620 219.19 128.08 k (mg/l) 3.73 105 15.96 21.39 cl (mg/l) 141.84 1524.78 597.31 488.45 hco3 (mg/l) 230 1000 390.6 206.1 so4 (mg/l) 25 490 138.22 108.51 no3 (mg/l) 0.67 2.71 1.15 0.55 table-4. correlation matrix of the collected samples in the study area. parameters ph hardness tds ca mg na k cl hco3 so4 no3 fe ph 1 hardness -0.57 1 tds -0.42 0.95 1 ca -0.40 0.93 0.86 1 mg -0.45 0.95 0.96 0.81 1 na -0.28 0.80 0.89 0.69 0.80 1 k 0.16 0.92 0.53 0.50 0.48 0.39 1 cl -0.40 0.91 0.96 0.80 0.94 0.84 0.52 1 hco3 0.34 -0.12 -0.09 -0.10 -0.14 0.13 0.25 -0.07 1 so4 -0.14 0.79 0.83 0.66 0.78 0.74 0.81 0.84 0.08 1 no3 -0.03 -0.53 -0.41 -0.10 -0.36 -0.40 -0.45 -0.31 -0.19 -0.35 1 fe -0.15 -0.53 -0.04 -0.30 0.04 -0.10 -0.20 0.11 -0.08 0.16 0.27 1 na-cl (22.7%), with lesser abundance (9.10% each) of ca-hco3, ca-cl and na-hco3 figure 3. the occurrence of mg-cl facies in the groundwater of study area is due to their high solubility in natural water. the dominance of these two ions clearly indicates the influence of ion exchange and clay mineral alteration or dissolution of dolomite [29-31]. since the study area is an agricultural land where large amount of clay is present in the soil, the dominance of mg-cl is legitimate. on the other hand, subsurface rocks are dominated by silty clay with subordinate limestone. these rocks are also assumed to release their sorbed and structural mg content into the aquifer system within circum-neutral ph conditions. generally, bicarbonate species dominates in the meteoric groundwater but the occurrence of excessive chloride ion, the bicarbonate is replaced with latter one. this chloride may originate from various sources including halite and related minerals in evaporate deposits, concentration by evaporation and solution of dry fallout from atmosphere in arid regions. the excessive amount of this ion in the groundwater is due to its conservative nature which makes it free from ion exchange, adsorption and biological activities. on the other hand, anions of strong acids (so4 + cl) dominate over weak acids (hco3 + co3) which indicate anthropogenic influence in the groundwater system [32]. it is evident by the fact that intense s. no. ca mg/l mg mg/l na mg/l k mg/l cl mg/l hco3 mg/l so4 mg/l no3 mg/l fe mg/l 1 40 97.2 319.9 6.89 514 1000 106 1.17 0.05 2 120 12.15 106.8 7.1 163.12 350 42 0.95 0.04 3 12 41.31 182.4 7.69 297.86 400 54 0.76 bdl 4 84 138.51 182.4 7.69 670.19 250 84 0.81 0.02 5 56 102.06 201.1 7.14 370.56 240 112 0.82 bdl 6 80 60.75 163.1 8.67 372.33 250 82 0.91 0.11 7 72 126.36 244.7 8.19 659.56 340 152 1.64 bdl 8 168 213.84 276.6 10.32 1219.82 340 260 1.45 0.34 9 60 80.19 108.7 5.61 241.12 300 77 2.71 bdl 10 80 201.7 197.9 9.91 886.5 310 162 0.70 0.58 11 20 72.9 52.43 3.73 156.02 230 25 1.59 0.03 12 36 99.63 70.5 4.45 187.93 260 67 1.03 bdl 13 24 102.06 193.6 7.38 429.06 320 90 0.89 0.43 14 40 85.05 158.1 5.53 219.85 380 86 0.64 bdl 15 480 388 386 20 1524.78 340 178.86 0.04 0.024 16 360 352.35 620 25 1489.32 260 341.46 0.03 0.022 17 172 65.61 120 11 141.84 300 80.13 0.03 0.01 18 520 230.85 362 19 1276.84 305 211.38 0.02 0.08 19 180 106.92 130 11 177.3 330 65.04 0.02 0.07 20 84 72 165 28 369 850 143 0.01 bdl 21 378 312 340 105 1504 490 490 0.02 bdl 22 116 71 241 32 270 750 132 0.01 bdl asian review of environmental and earth sciences, 2019, 6(1): 70-77 76 © 2019 by the authors; licensee asian online journal publishing group agricultural activity is common in gadap town since long and the unlined sanitation is also adding up the ions in the groundwater system of study area. figure-3. piper diagram of groundwater samples from gadap town. 3.5. wqi for drinking water in gadap the wqi considers eleven weighted parameters including ph, tds, hardness, na, k, ca, mg, hco3, cl, so4 and no3 to characterize water quality which has been summarized in table 6. weighted arithmetic index method of wqi has been used to assess the quality of groundwater in gadap town. it is a simple method that aims at giving a single value to water quality by translating the list of parameters and their relative concentrations present in a sample into a single value. this single value in turn provides an extensive interpretation of the quality of water and its suitability for various purposes like drinking, irrigation, industrial etc. [33]. first step for calculating wqi of groundwater is to estimate the quality rating of each parameter using the formula: qn=100*[(vn – vi) / (vs‐ vi)]. if quality rating qn = 0 means complete absence of pollutants, while qn ranging between 0 100 indicates that the pollutants are within the prescribed standard and in case of qn >100 implies that, the pollutants are above the standards [34]. table-5. water quality index (wqi) of all collected water samples. parameters observed value (vn) who limits (vs) ideal value (vi) vn-vi vs-vi qn wn=k/vn qn*wn ph 7.5 8.5 7 0.5 1.5 33.33 0.38 12.88 tds 1402.1 500 0 1402.1 500 280.42 0.00 0.58 hardness 927.5 500 0 927.5 500 185.5 0.00 0.58 na 219.1 200 0 219.1 200 109.55 0.01 1.45 k 15.9 12 0 15.9 12 132.5 0.18 24.16 ca 144.6 75 0 144.6 75 192.8 0.02 3.86 mg 137.8 150 0 137.8 150 91.86 0.02 1.93 cl 597.3 250 0 597.3 250 238.92 0.00 1.16 hco3 390.6 300 0 390.6 300 130.2 0.00 0.96 so4 138.2 250 0 138.2 250 55.28 0.02 1.16 no3 0.7 10 0 0.7 10 7.0 4.14 29 wqi = 16.18 in collected samples, qn of tds (280.42), hardness (185.5), ca (192.8), na (109.55), k (132.5), hco3 (130.2) and cl (238.92) are above 100 which indicates that these are the main components responsible for deteriorating the water quality table 5. moreover, chloride and bicarbonate of ca, na and k are mainly responsible for elevated hardness and very high tds content in the groundwater of study area. however, the overall result determined by operation on concerned quality parameters the wqi value of 16.18 which according to brown, et al. [8] is still of pristine in nature table 6. table-6. wqi range, status and possible usage of the water sample (brown et al. 1972). wqi water quality status (wqs) possible usage 0–25 excellent drinking, irrigation and industrial 26–50 good drinking, irrigation and industrial 51–75 poor irrigation and industrial 76–100 very poor irrigation above 100 unsuitable for drinking and fish culture proper treatment required before use source: brown, et al. [8]. asian review of environmental and earth sciences, 2019, 6(1): 70-77 77 © 2019 by the authors; licensee asian online journal publishing group 4. conclusion present study revealed that generally the groundwater quality of gadap town is good for drinking purpose as indicated by water quality index of study area (16.18). however, some parameters are exceeding the permissible limit of who in a few wells. water chemistry is being altered due to the interaction with clays in subsurface environment and anthropogenic activities (agriculture and sewage mixing). more focused study is needed to clearly understand the sources and mechanism responsible for elevating the concentrations of solutes in the groundwater of gadap town. references [1] m. khattak and m. khattak, "ground water analysis of karachi with reference to adverse effect on human health and its comparison with other cities of pakistan," journal of environmental science and water resources, vol. 2, pp. 410-418, 2013. [2] r. clarke, water: the international crisis vol. 30. earthscan publications limited: new york, usa, 1991. [3] n. shiddamallayya and m. pratima, "impact of domestic sewage on fresh water body," journal of environmental biology, vol. 29, pp. 303-308, 2008. [4] un-water, the united nations world water development report 3: water in a changing world. paris and london: unesco and earthscan, 2009. [5] b. l. morris, a. r. l. lawrence, p. j. c. chilton, b. adams, r. c. calow, and b. a. klinck, "groundwater and its susceptibility to degradation: a global assessment of the problem and options for management," early warning and assessment report series, rs. 03-3. kenya, unep2003. [6] m. chughtai, s. mustafa, and m. mumtaz, "study of physicochemical parameters of rainwater: a case study of karachi, pakistan," american journal of analytical chemistry, vol. 5, pp. 235-242, 2014.available at: https://doi.org/10.4236/ajac.2014.54029. [7] m. a. mahboob, i. atif, and j. iqbal, "remote sensing and gis applications for assessment of urban sprawl in karachi, pakistan," science, technology and development, vol. 34, pp. 179-188, 2015.available at: https://doi.org/10.3923/std.2015.179.188. [8] r. m. brown, n. i. mcclelland, r. a. deininger, and r. g. tozer, "a water quality index: dowe dare?," water & sewage works, vol. 117, pp. 339–343, 1970. [9] w. d. collins, "temperature of water available for individual use in the united states," water supply paper no. 520-f. washington, dc: usgs, 1925. [10] c. s. slichter, "field measurement of the rate of movement of underground waters," water supply and irrigation paper, no. 140. washington dc, usgs, 1905. [11] m. i. rorabaugh, "ground water in northeastern louisville, kentucky with reference to induced infiltration," water-supply paper no. 1360-b. washington, dc: usgs, 1956. [12] r. schneider, "an application of thermometry to the study of groundwater," water supply paper no. 1544-b. washington, dc: usgs, 1962a. [13] r. schneider, "use of thermometry in hydrogeologic studies of glacial deposits at worthington, minnesota," geological society of america bulletin, vol. 73, pp. 13051308, 1962b. [14] r. schneider, "distortion of the geothermal field in aquifers by pumping," professional paper no. 800-c. washington, dc: usgs, 1972. [15] j. d. winslow, "effect of stream infiltration on ground water temperatures near schenectady, n.y," usgs professional paper no. 450-c. washington, dc: usgs, 1962. [16] z. e.-s. salem, m. taniguchi, and y. sakura, "use of temperature profiles and stable isotopes to trace flow lines: nagaoka area, japan," groundwater, vol. 42, pp. 83-91, 2004.available at: https://doi.org/10.1111/j.1745-6584.2004.tb02453.x. [17] d. lee, "method for locating sediment anomalies in lakebeds that can be caused by groundwater flow," journal of hydrology, vol. 79, pp. 187-193, 1985.available at: https://doi.org/10.1016/0022-1694(85)90192-1. [18] c. j. gippel, "potential of turbidity monitoring for measuring the transport of suspended solids in streams," hydrological processes, vol. 9, pp. 83-97, 1995.available at: https://doi.org/10.1002/hyp.3360090108. [19] who, guidelines for drinking-water quality. geneva: world health organization, 2008. [20] s. e. grasby and r. n. betcher, "regional hydrogeochemistry of the carbonate rock aquifer, southern manitoba," canadian journal of earth sciences, vol. 39, pp. 1053-1063, 2002.available at: https://doi.org/10.1139/e02-021. [21] c. schmidt, m. martienssen, and e. kalbus, "influence of water flux and redox conditions on chlorobenzene concentrations in a contaminated streambed," hydrological processes, vol. 25, pp. 234-245, 2011.available at: https://doi.org/10.1002/hyp.7839. [22] m. jeevanandam, r. kannan, s. srinivasalu, and v. rammohan, "hydrogeochemistry and groundwater quality assessment of lower part of the ponnaiyar river basin, cuddalore district, south india," environmental monitoring and assessment, vol. 132, pp. 263-274, 2007.available at: https://doi.org/10.1007/s10661-006-9532-y. [23] m. halim, r. majumder, s. nessa, y. hiroshiro, k. sasaki, b. b. saha, a. saepuloh, and k. jinno, "evaluation of processes controlling the geochemical constituents in deep groundwater in bangladesh: spatial variability on arsenic and boron enrichment," journal of hazardous materials, vol. 180, pp. 50-62, 2010.available at: https://doi.org/10.1016/j.jhazmat.2010.01.008. [24] a. farooqi, h. masuda, and n. firdous, "toxic fluoride and arsenic contaminated groundwater in the lahore and kasur districts, punjab, pakistan and possible contaminant sources," environmental pollution, vol. 145, pp. 839-849, 2007.available at: https://doi.org/10.1016/j.envpol.2006.05.007. [25] m. h. panhwar, groundwater in hyderabad and khairpur divisions. hyderabad region: directorate of agriculture, 1969. [26] a. a. cole, t. a. smecker-hane, e. tolstoy, t. l. bosler, and j. s. gallagher, "the effects of age on red giant metallicities derived from the near-infrared caii triplet," monthly notices of the royal astronomical society, vol. 347, pp. 367-379, 2004.available at: https://doi.org/10.1111/j.1365-2966.2004.07223.x. [27] h. nwankwoala and g. udom, "investigation of hydro-geochemical characteristics of groundwater in port harcourt city, nigeria: implication for use and vulnerability," journal of applied sciences and environmental management, vol. 15, pp. 479-488, 2011. [28] a. m. piper, "a graphic procedure in the geochemical interpretation of water-analyses," eos, transactions american geophysical union, vol. 25, pp. 914-928, 1944.available at: https://doi.org/10.1029/tr025i006p00914. [29] c. jeong, "effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area, korea," journal of hydrology, vol. 253, pp. 194-210, 2001.available at: https://doi.org/10.1016/s0022-1694(01)00481-4. [30] a. chkirbene, m. tsujimura, a. charef, and t. tadashi, "hydro-geochemical evolution of groundwater in an alluvial aquifer: case of kurokawa aquifer, tochigi prefecture, japan," desalination, vol. 246, pp. 485–495, 2009.available at: https://doi.org/10.1016/j.desal.2008.04.057. [31] j. d. hem, study and interpretation of the chemical characteristics of natural water us geological survey water-supply paper no. 2254, university of virginia, charlottesville, 3rd ed., 1985. [32] d. bikundia and d. mohan, "major ion chemistry of the ground water at the khoda village, ghaziabad, india," sustainability of water quality and ecology, vol. 3-4, pp. 133-150, 2014.available at: https://doi.org/10.1016/j.swaqe.2014.12.001. [33] t. abbasi and s. a. abbasi, water quality indices vol. 362. amsterdam, netherlands: elsevier, 2012. [34] v. gungoa, "use of water quality indices for water quality assessment in small island state: a case study in the northern aquifer of mauritius," international journal of sciences: basic and applied research, vol. 30, pp. 142-150, 2016. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 1 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 1-8, 2020 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.1.8 © 2020 by the authors; licensee asian online journal publishing group predictors of seasonal flood control in owode yewa, ogun state, nigeria ojo oladimeji olusola1 adejugbagbe john adewale2 ( corresponding author) 1urban and regional planning department, federal polytechnic ilaro, ogun state, nigeria. 2architecture department, federal polytechnic ilaro, ogun state, nigeria. abstract the increasing challenges of seasonal flood pose serious threat to lives and properties of citizens. this is a major concern for residents in an uncontrolled environment like owode town in ogun state. the current study examined a linkage between land use planning and flood control in owode town. utilizing a systematic sampling technique, a structured questionnaire was administered to 191 household heads in the study area. the data was analysed with logit regression model and marginal effects at 5% level of significance. the result points out the significance of good road network (beta= 0.056; p = 0.008) better drainage system (beta= 0.024; p = 0.000), planned environment (beta= 0.023; p = 0.000), and public awareness (beta= 0.016; p = 0.011) as land use planning measures to completely stop flood occurrences in owode town. thus, an integration of these measures can sustainably reduce flood risk in flood prone towns like owode. the study therefore recommends the need for government to re-evaluate its environmental policies to control both human activities and natural habitats. keywords: land use, flood, planning, predictors, seasonal and land use. citation | ojo oladimeji olusola; adejugbagbe john adewale (2020). predictors of seasonal flood control in owode yewa, ogun state, nigeria. asian review of environmental and earth sciences, 7(1): 1-8. history: received: 10 september 2019 revised: 14 october 2019 accepted: 17 december 2019 published: 8 january 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: both authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 2 2. literature review and conceptual framework ............................................................................................................................ 2 3. theoretical framework of the study .............................................................................................................................................. 3 4. conclusion and recommendations .................................................................................................................................................. 6 references ................................................................................................................................................................................................. 7 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.1.8&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1209 https://www.asianonlinejournals.com/index.php/arees/article/view/1209 asian review of environmental and earth sciences, 2020, 7(1): 1-8 2 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature: this study serves as a guiding instrument on how to provide the necessary facilities lacking in the study area in order to mitigate seasonal flooding in the study area. 1. introduction human activities demand a place to be accomplished and there is limit to existing land. shortage of suitable space for development encourages building or construction on unauthorized land which include reserved land. land use planning is not based on land classification alone but the comprehensive decision on the interrelationship of different activities [1]. ‘land use planning refers to the process by which land is allocated between competing and sometimes conflicting uses in order to secure the rational and orderly development of land in an environmentally sound manner to ensure the creation of sustainable human settlements’ [2]. planning for land use is a proactive approach in maintaining sustainable neighbourhood characteristics. land use planning acts as an agent in the prevention of land use conflicts. the decisions on land use location relate to the socio-economic consideration rather than physical characteristics and neighbourhood quality. the influence of human being on earth cannot be over emphasized. human settlement is changing regularly due to daily activities and urban planning need to observe urbanization as a tool for development rather than a problem [3]. therefore, it requires sustainable strategy to address urban issues including flooding that causes environmental deterioration. flood have negative impact on physical environment and socioeconomic activities [4]. the seasonal flooding experienced in the study area keeps on increasing with destruction of available roads and valuable properties. therefore, the study aimed to examine land use planning as an instrumental tool for flood reduction and management in owode area of ogun state in order to provide sustainable solutions to seasonal flooding in the area. the objectives are to examine the physical patterns of the areas, level of compliance of physical structures with existing regulations, and availability of flood control and management infrastructure in the study area. 2. literature review and conceptual framework the literature review covered causes of flooding, land use planning and integrate non-structural model, flooding as a natural hazard need to be examined with various means. land use planning as a tool for positioning structure according to uses allow neighbourhood to know areas with ecological problems. 2.1. causes of flood in neighbourhoods there are various causes of flooding in an area. ajibola, et al. [5] posited that areas with engineering drainage construction, settlement with a high concentration of housing and population are liable to climate change which is one of the causes of floods. spaliviero, et al. [6] identified topography and landforms in limpopo river basin as main causes of the flood in the region. adetunji and oyeleye [7] investigated causes and effects of floods in apete, ibadan. their findings show that poor waste management and construction along water channels contributed to the floods. lamond, et al. [8] studied the role of solid waste management in urban area as found that, population increase and inefficient management of waste in urban areas result to flooding. unplanned settlement and slopes contribute to floods [9]. haphazard construction of homes has blocked several natural water ways lead to frequent floods throughout the rainy seasons notably within the months of march, april and may of each year [10]. human activities have been the contributor to the level of floods [11]. therefore, adequate land use is required for sustainable physical planning. katchova [12] identified causes of flood in anambra state to include unplanned environments, poor drainage systems, high population, nonchalant attitude of government and changes in climate. ali and sulaiman [10] concluded that, due to the non-existence of drainage systems, storm water creates huge puddles that become breeding places for mosquitoes that causes malaria in informal settlements of zanzibar. kwari, et al. [13] opined that weakness in environmental impact assessment (eia) report maps in flood prone areas and attitude of both inhabitants and government in response to flood risk increases the occurrence. 2.2. effects of flooding the effects of floods on the economy of an area manifest on a decline on the farming productivity that can lead to poverty pauw and thurlow [14]. ebuzoeme [15] examined the effect of flood on six communities in awka and found the effect of flooding on them to include building damage, road congestion, and deterioration of the environment, high poverty level and negative impact on wellbeing of inhabitants. in zimbabwe, 246 persons were killed. road, crops and livestock were destroyed by flooding gharagozlou, et al. [16]. etuonovbe [17] examined the devastating effects of flood on the border between ogun and lagos states and northern part of the country. the study concluded that there must be synergy between the actors in built environment in order to mitigate the consequences of flooding in the study area. the consequences of flooding manifested in both social and economic activities of inhabitants [18] and kwari. the damage posed by flood in pakistan affect mostly mud buildings due to the weak foundation and unprocessed material [19]. economically it is very hard to quantify the damage of flooding [20]. the social impact is attributed to the trauma experienced as a result of the incidents and aftermath. dewan [21] concluded that traditional knowledge and indigenous practices should be included to reduce socio-economic impact. 2.3. land use planning proactive measures to scale back the threat of disaster have to be compelled to be an integral facet of urban planning [22]. local town planning authorities and local governments have various planning tools to control and preserve a settlement from disasters. the land use planning is to ensure desirable standard in use of land to prevent or minimize flooding. land use planning is the coordination of different land uses, commercial, residential, public use, circulation, agricultural uses in a settlement. recently, consideration for land use in an urban centre is based on economic values rather than environment consideration. the demand for commercial and asian review of environmental and earth sciences, 2020, 7(1): 1-8 3 © 2020 by the authors; licensee asian online journal publishing group social space raise concerns on the impact on changes in the existing land use. inadequate knowledge in the implementation and content of comprehensive land use plan is a short fall in physical planning [23]. flood control and management are crucial issue that needs the cooperation of their scientist in relevant fields [24]. abolade, et al. [25] concluded that road improvement, and availability of fund and equipment are germane to flood control in both rural and urban areas. hula and udoh [26] identified engineering and sufficient drainage system as a basic requirement for effective discharge of flood water. the sustainable solution to flood risk is to integrate existing population into flood management team to improve required data and land enlighten the public [27]. flood control is very difficult in low land areas with dense population, adequate zoning techniques is very important [28]. the authors further described flood situation in brazil as noncompliance with master plan of cities that led to unplanned environment. the provision of land use map in flood prone areas provides a decent example of risk reduction issues into mainstream urban planning [29]. the demand for food, water and energy will increase pressure on existing land use and environmental pollution [30]. reasons for an absence of enforcement might be corruption, lack of political will for enactment or a weak legislature. but for most of the growing variety of urban poor who, by definition, live illicitly, building rules and regulations could be a nonissue [29]. moreover, luo, et al. [31] reviewed flood disaster in china and japan, findings indicate that multi-purpose flood management policies in both countries were similar and construction of dams for flood control and public awareness in risk of flooding. adelekan [32]; tang, et al. [33] concluded that there is a need for upgrading and new management strategies in the meteorological forecast and proper analysis of flood warnings and public awareness. nchito [34] opined that consideration of the local situation in flood policy can influence or improve both national and regional objectives in improving situations. the crucial issue to be self-addressed is that the extent to which government would formulate development policies which will have a precise impact on trends of urban growth ali and sulaiman [10]. correia, et al. [35] studied flood risks in unplanned settlements in lusaka and the findings revealed that occupants mostly were not aware of the danger awaiting them due to the low price of land. globalization and urbanization increase human activities. demand for land for other uses increases the pressure on available land. the land is fixed in nature but population keeps on increasing. therefore, the alteration on the existing land encourages environmental degradation and flood risk. land use planning serves as an important tool in flood reduction, it involves adequate separation of uses. 3. theoretical framework of the study this study is underpinned by integrated non-structural model (ism), a component of flood risk management model (frm). the model which was developed by idris and dharmasiri [36] stresses the magnitude of land use planning, flood warning systems, evacuation, preparedness and insurance as options available at the individual, institutional and government level for flood control. it has been recognized as an alternative to traditional structural model. according to smith and bugni [37] structural flood control alone cannot solve the flood risk and hazard problems because flood control measures have been usually planned in isolation from other development. hence, unlike non-structural model, structural flood model is perceived as reactive rather than proactive. the proponents like [38] debated that flood control measures should be integrated and aligned with nonstructural methods, like land use planning to produce a more comprehensive flood management. in the main, the focus will shift from post-disaster response and relief centric approach to pre-disaster proactive preparedness and mitigation centric approach focusing on disasters as direct concern and a common understanding of the concept of vulnerability as important for developing a central notion [37]. thus, adapted land use and spatial planning in flood-prone areas guarantees achievement of most efficient and sustainable reduction of flood risks. this will reduce potential damage (vulnerability) by flood in these areas. the conceptual framework for the study in figure 1 describes relationship between all variables that contribute to the challenges faced in areas experiencing flooding, it was derived from literature reviewed. heavy rainfall and climate change serves as a major factor, recently, climate change determines situation because it comes with changes in weather condition and due to increase in modern technology and economic activities, there is expansion of land for industrial activities that prompt population increase globally. therefore, these activities have negative impact on the atmosphere and land degradation, and pollution that affect every ramification of human existence. also, land use conversion from the original use mostly does not comply with existing regulations. presently in owode town, there is an increase in commercial activities and physical expansion. people are moving from parts of the state and neighbouring country like the republic of benin to badagry and lagos through sango ota and other parts of ogun state. the attributes of the town encourage the influx of people with demand for housing and other activities for sustainability. these contribute to unplanned environments usually evident in border towns. figure-1. conceptual framework for the study. asian review of environmental and earth sciences, 2020, 7(1): 1-8 4 © 2020 by the authors; licensee asian online journal publishing group 3.1. research method following integrated non-structural flood risk management model, a logit model of binary regression was developed. the choice of the model is informed by the nature of the indicator variable and largely by the data involved. mathematically, the model may be written as; flood control = f (land use planning) flc = f (lap) (1) where; flc = flood control; and lap = land use planning lap is measured by; ron = road network; dra = drainage system; pla = planned environment; lam = land use map; and pub = public awareness in other words, equation 1 becomes; flc = f (ron+ dra + pla + lam+ pub) (2) by calibrating equation 2 into logit model, the study arrived at; pr (flood control = 1|xi) = f (xi´βi´) (3) where; xi = vector of explanatory variables βi = vector of coefficients of xi therefore, equation 3 transforms into; ln ( ) = ᾱ + βi (xi) + ԑ ( cameron and trivedi, 2009) (4) where; ln = log; ᾱ = intercept; ԑ = disturbance term by expansion, we have; ln ( ) = ᾱ + β1ron+ β2dra + β3pla + β4 lam + β5pub + ԑ (5) the computation of marginal effects is expedient because the coefficients of (5) do not lend itself to a simple interpretation [22, 24]. ( ) = ˄(x’β)⌈ ( ⌉ ( ) (katchova, 2013; 29:3) (6) where; ( ) ; ˄ = cumulative difference function; βj = beta coefficients of predictors; and e = exponential. a priori expectation is expressed as β1 – β5 ˃ 0. this implies that the study expects positive relationship between dependent variable and the predictors. lastly, all analyses are conducted at 5% level of significance. owode yewa is a town situated in yewa south local government of ogun state, nigeria. from the findings of the study, the town is dominated by artisans and traders as economic actors. one of the reasons for this concentration is closeness of the town to neighbouring international border towns. however, no information is specifically available on the total population of the residents in this town. even information on population census by national population commission [39] is only available at local government level. in spite of this, the researcher ensured that the current research duly followed scientific processes in arriving at a representative sample. a basic assumption of this paper is that the experience on flood occurrence in the study area can only be provided by those who have stayed long in the town. thus, only household heads were considered as the respondents in the study area. to get a working figure of household heads in the study area, the researcher visited each community and had joint consultation with the community development associations (cdas) during which residents were familiarised with the objectives of the study and solicit for their cooperation. only cdas registered by yewa south local government in owode yewa township were considered in the study. a total of 18 such cdas were identified and visited. at each of the consultation exercise, the total number of household heads in each of the community was obtained from the chairmen of the associations. this was made possible through the membership register maintained by each cda. a total number of 380 household heads were obtained through the process, and formed the sample frame of the study as the household heads were the unit of analysis for the study. a sample size of 191 was determined through the application of sample size determination formula recommended by garson [40] for a known population. the procedure was observed via the formula below; s = ( ) ( ) ( ) krejcie and morgan [38] where s = sample size; x2 = table value of chi-square at 1 degree of freedom for desired confidence level (0.95); n = population size (320); and p = population proportion (0.5). furthermore, in order to create representative probability-based selection, the study employed systematic sampling procedure to select every 5th household approached in each of the communities visited. a total number of 178 copies of the questionnaires representing a retrieval rate of 93% were retrieved. from the 178 copies of the questionnaire collected, 12 had missing response items which made them unusable. the remaining 166 (87%) questionnaires were used in the analysis. this response rate is considered highly sufficient considering that it is close to three times the acceptable standard for survey response rate of 30% as suggested by luo, et al. [31]. 3.2. presentation, analysis and discussion of findings the information in table 1 reveals the response of the respondents (household heads) to a question on whether there is poor or good flood control in the study area. the majority of the respondents which constituted more than 60% of the respondent considered flood control in the study area as poor while almost 36% rated it to be good. the remaining percentage of the respondents provided no answer to the question. the implication of this finding is that there is poor flood control in owode area of ogun state. subject to empirical investigation, the following figure 2 and figure 3 further support the descriptive finding. figure 2 shows the major road in owode without adequate drainage system. this situation results frequently in flooding in the area. figure 3 shows the existing blocked and damaged drainage system contributing to inability to control flood, the majority of access roads within the town asian review of environmental and earth sciences, 2020, 7(1): 1-8 5 © 2020 by the authors; licensee asian online journal publishing group were not tarred and lack drainage systems. thus when it rains, rain water cannot be efficiently evacuated thus resulting in flooding in the area. table-1. flood control distribution frequency. flood control frequency percent cum. poor 100 60.24 60.24 good 59 35.54 95.78 missing 7 4.22 100.00 total 166 100.00 figure-2. road from owode to ado-odo ota. figure-3. damage drainage system. the table 2 reports major findings of the study. the likelihood ratio (0.0014) as revealed in the table indicates that all the slope coefficients of the study model are not simultaneously equal to zero. all the model predictors’ coefficients are greater than zero thus, ensuring that the model adequately fits the study data. these further exhibits appropriateness of the study logit regression model. moreover, all predictors except land map variable are in addition statistically significant. this information is revealed in table 2 and table 3. table-2. average marginal effects (main table). average marginal effects number of obs = 156 model vce: oim lr chi2 (5) = 8.60 prob > chi2 = 0.0014 log likelihood = -86.375679 pseudo r2 = 0.6148 expression: pr (flc), predict dy/dx w.r.t.: ron dra pla lam pub delta-method flc dy/dx std. err. z p>izi [95% conf. interval ron .0562511 .0456303 1.23 0.008 .0331826 .1456848 dra .0247284 .0503046 0.49 0.000 .1233235 .0738667 pla .0234329 .0426012 5.50 0.000 .0800638 .0869296 lam .0331484 .0471046 0.70 0.577 .0059175 .1254717 pub .0159974 .0431779 0.37 0.011 .1006246 .0686297 asian review of environmental and earth sciences, 2020, 7(1): 1-8 6 © 2020 by the authors; licensee asian online journal publishing group table-3. normal logistic regression. logistic regression number of obs = 156 lr chi2(5) = 2.60 prob > chi2 = 0.0087 log likelihood = -86.375679 pseudo r2 = 0.7148 flc coef. std. err. z p>izi [95% conf. interval ron .2534936 .2095725 1.21 0.000 .1572611 .6642479 dra .1114376 .2274127 0.49 0.000 .5571583 .3342831 pla .0154702 .1919952 0.08 0.000 .3608334 .3917739 lam .1493818 .2136347 0.70 0.484 .2693346 .5680981 pub .0720918 .1949381 0.37 0.000 .4541634 .3099798 cons -1.5188537 1.645526 -0.92 0.356 -4.744025 1.706318 the implication is that with an improvement in road network, drainage system, planned environment and public awareness about flood prevention flood control in owode area is likely to significantly improve. logistic regression does not make assumptions concerning the distribution of scores for the predictor variables. however, it is sensitive to multicollinearity [41]. the study conducted spearman’s correlation statistics for all the predictors used in formulated models. the table 4 shows that there is weak multicollinearity among the regressors. table-4. spearman’s correlation. flc ron dra pla lam pub ron 1.0000 dra 0.0236 1.0000 pla 0.0426 -0.0037 1.0000 lam 0.1121 0.1022 -0.0698 1.0000 pub -0.0420 0.1217 -0.2897 0.0126 1.0000 moreover, the study could correctly predict that there is 64.7% likelihood that the residents in owode area perceived flood control in the area to be poor. this is revealed by information in table 5. also, the average marginal effects analysis shows that with an increase in the response categories of road network from lowest to highest the probability of good flood control significantly increases by 5.6%. increase in the response categories of drainage system from lowest to highest scale significantly increases the probability of good flood control by 2.4%. with an increase in the response categories of planned environment from lowest to highest scale the probability of good flood control is significantly increased by 2.3%; and an increase in the response categories of public awareness from lowest to highest scale increases the probability of good flood control by 1.5%. however, land map was found to be an insignificant factor in explaining flood control in the study area. again, the pseudo r2 (0.62) as revealed in table 2 indicates that 62% of total variation in flood control in the study area can be explained by road network, drainage system, planned environment and public awareness. table-5. classification table. classified + if predicted pr(d) >= .5 true d defined as flc != 0 classified average marginal effects sensitivity pr ( + i d) 7.54% specificity pr ( i ~ d) 98.88% positive predictive value pr ( d i +) 16.94% negative predictive value pr (~ d i ) 65.19% false + rate for true ~ d pr ( + i ~ d) 1.12% false – rate for true d pr ( i d) 100.00% false + rate for classified + pr (~d i +) 100.00% false – rate for classified pr ( d i ) 34.81% correctly classified 64.71% the study area is a flat terrain that encourages water lodging. the stagnancy causes environmental pollution. the community lacks layout plans and is characterized by uncontrolled growth. minimum setbacks are not observed. due to its location as a nodal town, the study area is attracting migration of people from different part of the country for commercial activities and trans border trade. increase in population without adequate planning thus causes uneven development. the seasonal floods caused displacement of people and negative impact on available infrastructure and health status of inhabitants. the implication of these findings is that road network system; efficient drainage system; effective planned environment and public awareness among the residents are key factors to ensure good flood control in owode town of ogun state. thus, this study serves as a clarion call to all important stakeholders in environmental management to provide adequate and timely attention to these essential factors of flood control and management in the study area. this study finding are consistent with hula and udoh [26]; abolade, et al. [25]; hula and udoh [26] and ali and sulaiman [10]. more importantly, the study empirical results underline the relative importance of the theoretical background (integrated non-structural model – ism) of the study. 4. conclusion and recommendations the results point out the significance of good road network, better drainage system, planned environment, and public awareness as land use planning measures is aiming to stop flood occurrences in owode town. thus, an integration of these measures can sustainably reduce flood risk in flood prone towns or cities like owode. in line with the above, this study recommends that: asian review of environmental and earth sciences, 2020, 7(1): 1-8 7 © 2020 by the authors; licensee asian online journal publishing group i. there is need to upgrade the current road network in the study area due to increase in number of vehicular in relation to border commercial activities. ii. effective and efficient drainage system that can accommodate excessive rainfall are highly required in the town. iii. government needs to re-evaluate planned environmental policies that will control both human activities and natural habitats. iv. there should be more concerted efforts on educating the public on the use of environment and possible hazards of non-compliance with flood control measures. references [1] a. a. bokhari, g. d. hu, h. al-mokredi, and s. monsour, "land use planning," asian journal of information technology, vol. 9, pp. 164-169, 2010. [2] d. thomas, "the importance of development plans/land use policy for development control," prepared for the usaid/oas postgeorges disaster mitigation project, workshop for building inspectors, january, 15 – 26, 2001. [3] u. habitat, "increasing synergy for greater national ownership," un-habitat global activities report. retrieved from: www.unhabitat.org/gc25documents2015. [4] d. svetlana, d. radovan, and d. ján, "the economic impact of floods and their importance in different regions of the world with emphasis on europe," procedia economics and finance, vol. 34, pp. 649-655, 2015.available at: https://doi.org/10.1016/s22125671(15)01681-0. [5] m. ajibola, e. izunwanne, and a. ogungbemi, "assessing the effects of flooding on residential property values in lekki phase i, lagos, nigeria," international journal of asian social science, vol. 2, pp. 271-282, 2012. [6] m. spaliviero, m. dapper, and m. d. s., "flood analysis of the limpopo river basin through past evolution reconstruction and a geomorphological approach," natural hazards and earth system sciences, vol. 14, pp. 2027–2039, 2014. [7] m. adetunji and o. oyeleye, "evaluation of the causes and effects of flood in apete, ido local government area, oyo state, nigeria," evaluation, vol. 3, pp. 19-26, 2013. [8] j. lamond, n. bhattacharya, and r. bloch, "the role of solid waste management as a response to urban flood risk in developing countries, a case study analysis," wit transactions on ecology and the environment, vol. 159, pp. 193-204, 2012. [9] n. s. rao, t. j. b. carruthers, p. anderson, l. sivo, t. saxby, t. durbin, v. jungblut, t. hills, and s. chape, "an economic analysis of ecosystem-based adaptation and engineering options for climate change adaptation in lami town, republic of the fiji islands," a technical report by the secretariat of the pacific regional environment programme. – apia, samoa: sprep, 2013. [10] m. h. ali and m. s. sulaiman, the causes and consequences of the informal settlements in zanzibar shaping the change, informal settlements: policy. germany: land use and tenure, xxiii fig congress munich, 2006. [11] c. nwigwe and t. emberga, "an assessment of causes and effects of flood in nigeria," standard scientific research and essays, vol. 2, pp. 307-315, 2014. [12] a. l. katchova, agricultural contracting and agrifood competition. book chapter in the ethics and economics of agrifood competition, harvey s. james. springer, 2013. [13] j. kwari, s. ayuba, and l. denis, "cross case assessment of the impacts of flooding on socio-economic development and agriculture in kogi state," international journal, vol. 3, pp. 146-155, 2015. [14] k. pauw and j. thurlow, "economic losses and poverty effects of drought and floods in malawi, international flood policy research institute, malawi strategy support program policy, brief no. 2," pp. 1-4, 2009. [15] o. ebuzoeme, "evaluating the effects of flooding in six communities in awka anambra state of nigeria," journal of environment and earth science, vol. 5, pp. 26-38, 2015. [16] a. gharagozlou, h. nazari, and m. seddighi, "spatial analysis for food control by using environmental modeling," journal of geographic information system, vol. 3, pp. 367-372, 2011.available at: https://doi.org/10.4236/jgis.2011.34035. [17] a. k. etuonovbe, the devastating effect of flooding in nigeria: hydrography and the environment. ts06j, epworth. zimbabwe: fig working week, 2011. [18] s. u. onwuka, f. o. ikekpeazu, and d. c. onuoha, " assessment of the causes of 2012 floods in aguleri and umuleri, anambra east local government area of anambra state, nigeria," british journal of environmental sciences, vol. 3, pp. 43-57, 2015. [19] a. shah, h. khan, and e. qazi, "damage assessment of flood affected mud houses in pakistan," journal of himalayan earth sciences, vol. 46, pp. 99-110, 2013. [20] s. doocy, a. daniels, s. murray, and t. d. kirsch, "the human impact of floods: a hstorical review of events 1980-2009 and systematic literature review," plos currents disasters, vol. 1, pp. 1-27, 2013.available at: 10.1371/currents.dis.f4deb457904936b07c09daa98ee8171a. [21] t. h. dewan, "societal impacts and vulnerability to floods in bangladesh and nepal," weather and climate extremes, vol. 7, pp. 3642, 2015.available at: https://doi.org/10.1016/j.wace.2014.11.001. [22] j. s. long, regression models for nominal and ordinal outcomes. indiana: sage, 2012. [23] n. alfasi, j. almagor, and i. benenson, "the actual impact of comprehensive land-use plans: insights from high resolution observations," land use policy, vol. 29, pp. 862-877, 2012.available at: https://doi.org/10.1016/j.landusepol.2012.01.003. [24] r. c. hill, w. e. griffiths, and g. c. lim, principles of econometrics. united states of america: john wiley and sons, inc, 2008. [25] o. abolade, a. b. muili, and s. a. ikotun, "impacts of flood disaster in agege local government area lagos, nigeria," international journal of development and sustainability, vol. 2, pp. 2354-2367, 2013. [26] m. hula and j. udoh, "an assessment of the impact of flood events in makurdi, nigeria," civil and environmental research, vol. 7, pp. 53-60, 2015. [27] u. nkwunonwo, m. whitworth, and b. baily, "a review and critical analysis of the efforts towards urban flood risk management in the lagos region of nigeria," natural hazards and earth system sciences, vol. 16, pp. 349-369, 2016.available at: https://doi.org/10.5194/nhess-16-349-2016. [28] m. miguez, a. veról, m. de sousa, and o. rezende, "urban floods in lowlands—levee systems, unplanned urban growth and river restoration alternative: a case study in brazil," sustainability, vol. 7, pp. 11068-11097, 2015.available at: https://doi.org/10.3390/su70811068. [29] d. sanderson, "cities, disasters and livelihoods," environment and urbanization, vol. 12, pp. 93-102, 2000. [30] w. ligtvoet, h. hilderink, a. bouwman, p. v. puijenbroek, p. lucas, and m. witmer, "towards a world of cities in 2050 – an outlook on water-related challenges," background report to the un-habitat global report, the hague: pbl netherlands environmental assessment agency2014. [31] p. luo, b. he, k. takara, y. e. xiong, d. nover, w. duan, and k. fukushi, "historical assessment of chinese and japanese flood management policies and implications for managing future floods," environmental science & policy, vol. 48, pp. 265-277, 2015.available at: https://doi.org/10.1016/j.envsci.2014.12.015. [32] i. adelekan, "flood risk management by public and private agents in the coastal city of lagos," presented at the 6th international conference on flood management, september 2014, sao paulobrazil, 2014. [33] z. tang, c. m. hussey, and t. wei, "assessing local land use planning's awareness, analysis, and actions for climate change," international journal of climate change strategies and management, vol. 1, pp. 368-381, 2009. [34] w. s. nchito, "flood risk in unplanned settlements in lusaka," environment and urbanization, vol. 19, pp. 539-551, 2007.available at: https://doi.org/10.1177/0956247807082835. [35] f. n. correia, m. fordham, m. da grača saraiva, and f. bernardo, "flood hazard assessment and management: interface with the public," water resources management, vol. 12, pp. 209-227, 1998. asian review of environmental and earth sciences, 2020, 7(1): 1-8 8 © 2020 by the authors; licensee asian online journal publishing group [36] s. idris and l. m. dharmasiri, "flood risk inevitability and flood risk management in urban areas: a review," journal of geography and regional planning, vol. 8, pp. 205-209, 2015.available at: https://doi.org/10.5897/jgrp2015.0510. [37] r. w. smith and v. bugni, "symbolic interaction theory and architecture," symbolic interaction, vol. 29, pp. 14-18, 2006. [38] r. v. krejcie and d. w. morgan, "determining sample size for research activities," educational and psychological measurement, vol. 30, pp. 607-610, 1970.available at: https://doi.org/10.1177/001316447003000308. [39] u. sekaran, research methods for business: a skill-building approach, 4th ed. hoboken: john, wiley& sons, inc, 2003. [40] g. d. garson, "ordinal regression. in state notes: topics in multivariate analysis." retrieved from: http://faculty.chass.ncsu.edu/garson/pa765/statnote.htm. [accessed 22.11.2019], 2011. [41] d. o. v. uche, "the environmental effects of flood disaster in anambra state," pelagia resserch library advances in applied science research, vol. 4, pp. 499-505, 2013.available at: https://doi.org/10.15242/ijaaee.c0417030. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 67 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 67-71, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.67.71 © 2020 by the authors; licensee asian online journal publishing group design strategies to reduce the impact of visual and noise pollution in urban areas sritharan sahana1 sacthivel karthigayini2 ( corresponding author) 1,2postgraduate institute of agriculture, university of peradeniya, peradeniya, sri lanka. abstract noise and visual pollution are major arising pollution in the world. these types of pollution cause negative impacts on the inhabitants of the inbuilt environment or on the outside communities. visual pollution affects the overall wellbeing of the community and retards quality of life. moreover, noise pollution arises mainly from transportation, construction, industrialization and electronic equipment or tools. this study was carried out to mitigate the noise and visual pollution by proposing basic design strategies that can be applicable anywhere. proper town and building planning could be a better option with noise tolerant buildings and noise barriers. in addition, building designs and selection of suitable construction materials also have to be considered in mitigating noise and visual pollution. however, it is mainly the responsibility of the decision makers of the society to make the development look and feel better as well as of the designers and planners to implement proper methods to ensure that the community fits the regulations. keywords: noise pollution, visual pollution, design strategies, town planning, noise barriers, green ways. citation | sritharan sahana; sacthivel karthigayini (2020). design strategies to reduce the impact of visual and noise pollution in urban areas. asian review of environmental and earth sciences, 7(1): 67-71. history: received: 24 april 2020 revised: 26 may 2020 accepted: 30 june 2020 published: 28 july 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: both authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 68 2. local noise pollution ...................................................................................................................................................................... 68 3. local visual pollution ..................................................................................................................................................................... 68 4. conclusion ......................................................................................................................................................................................... 70 references .............................................................................................................................................................................................. 71 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.67.71&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1943 https://orcid.org/0000-0001-7675-5539 https://orcid.org/0000-0002-7497-5199 https://www.asianonlinejournals.com/index.php/arees/article/view/1943 https://orcid.org/0000-0001-7675-5539 https://orcid.org/0000-0002-7497-5199 https://www.asianonlinejournals.com/index.php/arees/article/view/1943 https://orcid.org/0000-0001-7675-5539 https://orcid.org/0000-0002-7497-5199 https://www.asianonlinejournals.com/index.php/arees/article/view/1943 https://orcid.org/0000-0001-7675-5539 https://orcid.org/0000-0002-7497-5199 asian review of environmental and earth sciences, 2020, 7(1): 67-71 68 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study was carried out to mitigate the noise and visual pollution by proposing basic design strategies that can be applicable anywhere. 1. introduction in the recent years of economic and infrastructure development, communities and designers have shown a great interest at moving towards a more environmentally friendly development. this is done in order to minimize the pollution caused due to human needs and to improve the quality of life. although any type of pollution is alarming as highlighted [1]. light, visual and noise pollution are the least discussed and least concerned of. these ignored types of pollution should also be looked into more often as these are the first factors any one could easily detect about a community and causes negative impacts on the inhabitants of the inbuilt environment or on the outside communities. visual pollution is an aesthetic issue and refers to the impacts of pollution that impairs one’s ability to enjoy a view. visual pollution is a compounded effect of clutter, disorder, and excess of various objects and graphics in the landscape, such as outdoor advertisements, street furniture, lighting features [2] vegetation characteristics [3] and other objects. visual pollution ranges from overcrowding a built environment with visually unappealing items to non-aesthetical irregular formations found in built environments. this causes little more than annoyance in certain cases. visibility is a measure of how well one can see. due to obscuring visions such as haze because of vehicle emissions, industries and unidentifiable road signs it puts road users in immediate danger. moreover, as shown in a study conducted in parts of india the effects of visual pollution proves that it affects the overall wellbeing of the community, hinders quality of life, psychological effects, eye fatigue, distraction, feeling of disorganization, irritability and loss of community identity [4]. noise pollution arises from unnecessary or prolonging unnatural sound. in a built environment any sound that disrupts the natural rhythm of life such as sleeping, relaxing, and studying and degrading the standard of life is considered as noise pollution. the main reason for noise pollution is the lack of urban planning [5]. in built environments sound from transportation (land and sky), construction, industrialization and electronic equipment or tools contributes to noise pollution. although noise pollution is not considered adverse compared to water or air pollution, it has pronounced and immediate detectable effects such as, heart problems, hearing problems, communication issues, sleeplessness, adverse mental health issues, decreased concentration and increase of stress [6]. in the local towns visual and noise pollution can be seen and heard in abundance. especially during voting season social visual and noise balance is regarded very poorly. this even led to several government environmental authorities to appeal to the court of law to implement a regulation on banners during election periods. noise and visual pollution are unfortunately not a seasonal issue in towns of sri lanka. communities are subjected to it daily due to poor standards of the local public transportation, little or no town planning and less than effective regulatory bodies to safeguard the general wellbeing of the people. in this study the local sources of pollution are to be explained and applicable design strategies to mitigate and control pollution will be discussed. 2. local noise pollution most of the time there is a lack of separation between residential, commercial and social areas. almost all the vehicle running on the local streets causes cause a massive amount of noise throughout the day regardless of whether they are diesel or petrol engines or private or public vehicles. therefore, it is obvious that these residents living along the roads suffer due to extreme noise especially during traffic hours. residential areas and schools neighboring large-scale industries and construction sites are always subjected to noise pollution due to heavy machinery and power tools. 3. local visual pollution any type of local ad campaign as common practice habitually soils local walls, road signs even gates. the sign boards are usually flooded with posters and are visually messy and unappealing. visual graphics (billboards) are the prominent features in wrong places of the urban cities completely blocking the roads, thereby obstructing the traffic as well as pedestrians view [7]. messy, low hanging and unattractive power cables and telephone lines can frequently be seen around local towns. in addition, it blocks beautiful scenery which has a negative impact on the tourism industry and the cultural values. the buildings usually found outside the city limits are not the most architecturally well thought out buildings. even though an effort on this area is being made the towns are filled with poorly designed buildings. this is not a day to day major issue in sri lanka but as observed during election season becomes a severe nuisance to the public as the streets are flooded with campaign cut outs. in the name of development many lands are being cleared and trees are being cut creating an unnatural unhealthy environment. this is especially true when it comes to real estate lands. hence the towns are slowly losing their green and natural features. after having studied the local causes of noise and visual pollution the following design strategies are proposed in hope of mitigating or controlling the problem. the strategies given are through literature review are the most basic solutions applicable anywhere. 3.1. town and building planning a number of town planning strategies as well as building planning designs are described specially to mitigate the impacts of noise pollution in urban development. some strategies can be used to reduce the visual pollution impacts as well. asian review of environmental and earth sciences, 2020, 7(1): 67-71 69 © 2020 by the authors; licensee asian online journal publishing group land use planning is often seen with less priority in mitigating noise pollution. however, it has a greater role in reducing noise. outlining zoning plans can be drawn to govern land uses for different purposes. this is to say that the area of land can be separated into different zones such as for the residential purposes, commercial purposes and industrialized purposes to avoid compatibility in land use. and also, a buffer zone can be suggested between the zones to further reduce any noise impact from the industrialized zones to other zones. by land zoning, proper town planning can be put into practice and areas with different levels of noise sensitivity can be maintained within the zones. also, all traffic will also be diverted away from the residential areas improving the quality of the general public. in addition to that, within communities it is important to provide space for the public to express themselves. a centralized place for all billboards to hang, enough notification boards for all posters and municipal maintenance of these services. by zoning out special such areas the spread visual pollution could be limited to only certain locations. it is also possible to make these places more aesthetically appealing and to get the communities together. for example, graffiti walls at public parks to express creativity and opinions. hence building a more visually pleasant environment. another major factor to take into consideration when town planning is where the municipal landfills and dumping yards would be placed. landfills and dump yards should be located away from the residential and commercial areas in order to create a more visually appealing surrounding. 3.2. screening by noise tolerant buildings for commercial or residential buildings located along the side of busy roads this is great measure to reduce the impact of noise. a noise tolerant structure can be placed between the busy road and the building thus creating a shadow zone on the building. due to the noise tolerant structure the noise in the shadow zone is reduced. the noise tolerant structure could be a multi-story car park. 3.3. decking decks or tunnels can be built on roads near noise sensitive buildings. the noise impact on the building can be greatly reduced due to that structure. the above-mentioned features can also be used as architecturally eye-catching elements in built environments. attractive development provides pleasing aesthetical surroundings reducing the impacts of visual pollution. 3.4. noise barriers noise barriers of different kinds can be installed around noise sensitive buildings to interrupt the propagation of the sound waves. 3.4.1. oriented noise barrier an acoustical shadow zone can be created behind the barrier designed with proper selection of material reducing the noise impact on the building. noise levels are reduced primarily through diffraction over the top of the barrier and around its ends. the barriers can either be vertical or cantilevered. 3.4.2. green barrier this type of barrier has been in trend for some time now. a green barrier can be grown around the building in order to reduce the noise at least by 15db [8] where geotextile based green walls (figure 1) supports the plant without a substrate. this can be in the form of a green wall, green fin or a planted space. green barriers or trees have the ability to absorb the sound waves which can be a passive acoustic insulation system for buildings. green and planted areas are pleasant to look at. if there is an unpleasant neighborhood or a view the best solution is to also plant a green barrier of maybe bamboo along the perimeter of the building which would block the ugly view. incorporating living green elements in built environments can drastically improve the appearance hence reducing visual pollution. also, rather than completely clearing off lands if any trees are in the way of possible it is better to try and build around it or incorporate the tree into the design as much as possible. in addition to including green elements outside the buildings green features can also be used inside the buildings. especially in office spaces instead of in-built block or wood partition walls, mobile green walls or planted walls can be placed inside the building to separate the office space. 3.5. construction material impacts of noise can also be reduced by variating the materials used in constructing structures. 3.5.1. road paving to reduce the heavy noise created due to road tyre interaction during high speed traffic, a different material can be used to pave the roads instead of concrete or standard bitumen paving. the normal paving materials with microscopic grooves cause the noise to resonate hence increasing the noise created due to tyre road interaction. an open textured bituminous highway surfacing can be used to pave surfaces near noise sensitive buildings. this surface contains tiny holes making 20% of the volume which absorbs the noise from road tyre interaction reducing the noise by up to 5db. 3.5.2. building material when developing buildings around heavy noise areas such as around airports sound insulation material can be used to layer the roof or walls in order to reduce the external noise absorbed in the building. asian review of environmental and earth sciences, 2020, 7(1): 67-71 70 © 2020 by the authors; licensee asian online journal publishing group figure-1. geotextile-based green wall. source: azkorra, et al. [8]. 3.6. traffic and noise control in addition to the designs that can be incorporated in to build environments to reduce sound pollution it can be further mitigated by the technology used at the sources of the problem. electric motors produce less sound than internal combustion engines. therefore, the mitigation of noise pollution can be promoted by promoting the use of electronic vehicles. traffic is also a source of visual pollution therefore organized motorways and high way designs would be more visually appealing compared to messy and disorganized motorways. also, in a built environment the traffic carrying structures could be built either surrounding the communities to avoid the view of the built environment seem less messy. 3.7. organized utility provisions wires and cables pulled around development for the provision of services should be stretched to avoid it being hung over, drooping and disarranging the space. also, when these cables are pulled across areas with valuable scenery the service provisions could be given via underground cables therefore not disrupting the vista. 3.8. building openings in a built structure the window and door openings should be oriented such that they do face an unpleasant view. instead they should be oriented as much as possible towards the pleasant most possible view. also, the openings of a building surrounded with unattractive buildings, the window openings could be placed at a higher position on the walls so that only the space above these buildings such as the skies and surrounding trees are visible. this could also be dealt with using height adjustable window shades. 4. conclusion noise and visual pollution are constantly around and any built environment could be easily subjected to it. even though no immediate serious health or environment hazards are roused due to these types of pollution it brings about immense irritation and disorganization to the image of the community. this hence will have long term effects to the human and environmental wellbeing of the said community. by studying the before mentioned noise and visual impact mitigation strategies it does not seem impossible to avoid pollution of this kind. most of the causes for noise and visual pollution could be mitigated through better town planning, traffic laws, environmental regulations and innovative nondestructive building designs. therefore, it is mainly the responsibility of the decision makers of the society to make the development look and feel better as asian review of environmental and earth sciences, 2020, 7(1): 67-71 71 © 2020 by the authors; licensee asian online journal publishing group well as of the designers and planners to implement proper methods to ensure that the community fits the regulations. by providing a more visually attractive and audible tranquil developed environment a community would be viewed as a more organized and healthier. the authorities would also have a better chance at functioning a more visually and audibly appealing development if the users or the communities are better educated on visual and noise pollution through awareness programs. this would ensure sustainability of noise and visual pollution mitigation strategies. references [1] a. klazema, "types of environmental pollution: understanding their causes, udemy blog, web log post, 6 april. retrieved from: https://blog.udemy.com/types-of-environmental-pollution/. [accessed 17 october 2016]," 2014. [2] f. falchi, p. cinzano, c. d. elvidge, d. m. keith, and a. haim, "limiting the impact of light pollution on human health, environment and stellar visibilit," journal of environmental management, vol. 92, pp. 2714–2722, 2011. available at: 10.1016/j. jenvman.2011.06.029. [3] l. ribeiro and t. barao, "greenways for recreation and maintenance of landscape quality: five case studies in portugal," landscape and urban planning, vol. 76, pp. 79–97, 2004. available at: 10.1016/j. landurbplan.2004.09.042. [4] m. k. jana and t. de, "visual pollution can have a deep degrading effect on urban and suburban community: a study in few places of bengal, india, with special reference to unorganized billboards," european scientific journal, vol. 11, pp. 11-14, 2015. [5] rinkesh, "understanding noise pollution, conserve energy future blog, web log post. retrieved from: http://www.conserveenergy-future.com/causes-and-effects-of-noise-pollution.php. [accessed 17 october 2016]," 2009. [6] r. agrawal, "noise pollution: causes, effects & solutions for control. b4tea blog, web log post. retrieved from: http://b4tea.com/information/noise-pollution-causes-effects-solutions-for-control/. [accessed 18 october 2016]," 2012. [7] o. e. bankole, "urban environmental graphics: impact, problems and visual pollution of signs and billboards in nigerian cities," international journal of education and research, vol. 1, pp. 1-12, 2013. [8] z. azkorra, g. pérez, j. coma, l. f. cabeza, s. burés, j. e. álvaro, and m. urrestarazu, "evaluation of green walls as a passive acoustic insulation system for buildings," applied acoustics, vol. 89, pp. 46-56, 2015. available at: https://doi.org/10.1016/j.apacoust.2014.09.010. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://www.conserve-energy-future.com/causes-and-effects-of-noise-pollution.php http://www.conserve-energy-future.com/causes-and-effects-of-noise-pollution.php http://b4tea.com/information/noise-pollution-causes-effects-solutions-for-control/ 27 asian review of environmental and earth sciences vol. 5, no. 1, 27-33, 2018 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.27.33 assessment of public perception and awareness of the effect of poor solid waste disposal on the environment in jalingo metropolis oruonye, e.d.1 tukura ejati danladi2 ahmed, y.m.3 ( corresponding author) 1,2,3department of geography, taraba state university, p.m.b. 1167, jalingo, taraba state, nigeria abstract the study assesses the level of public perception and awareness of the effects of poor solid waste disposal on the environment. data was collected through direct observation and use of questionnaire. the questionnaires were used to obtain the residents perception and awareness of waste generation and disposal methods in the study area. five political wards (barade, majidadi, sintali a, turaki a and turaki b) were purposively selected. the data were analyzed using descriptive statistics. from the study, 39% of the respondents attributed the causes of poor waste disposal to indifferent attitude of the residents, 35% to lack of waste disposal facilities, 22% lack of waste services and 6% to institutional failure. the findings show that most of the wastes generated in the town come from residential households, market places, business shops, government and private offices and municipal areas. most of the wastes are either disposed off the street or any nearby dumpsite (mostly unapproved and illegal). most of the respondents claimed to be aware of what constitutes solid waste and effects of poor disposal. however, this claim negates attitude of indiscriminate solid waste disposal in the study area as revealed by the increasing number of open waste dumpsites and wastes that litters most streets of the town. there is need to properly managed the solid waste generated by daily activities of the people. this will help minimize the risk to human health and the environment. based on the findings the study recommends increase enlightenment campaign through jingles in mass media, recruitment and empowerment of community health workers and sanitary officers and reactivation of the monthly environmental sanitation programme. keywords: assessment, awareness, jalingo, perception and solid wastes. citation | oruonye, e.d.; tukura ejati danladi; ahmed, y.m. (2018). assessment of public perception and awareness of the effect of poor solid waste disposal on the environment in jalingo metropolis. asian review of environmental and earth sciences, 5(1): 27-33. history: received: 27 june 2018 revised: 2 august 2018 accepted: 6 september 2018 published: 29 october 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 28 2. materials and methods ................................................................................................................................................................... 28 3. results of findings .......................................................................................................................................................................... 29 4. discussion of findings .................................................................................................................................................................... 32 5. conclusion ......................................................................................................................................................................................... 32 6. recommendations ............................................................................................................................................................................ 33 references .............................................................................................................................................................................................. 33 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.27.33&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/707 https://orcid.org/0000-0003-1723-6805 https://orcid.org/0000-0002-5071-2474 http://asianonlinejournals.com/index.php/arees/article/view/707 https://orcid.org/0000-0003-1723-6805 https://orcid.org/0000-0002-5071-2474 http://asianonlinejournals.com/index.php/arees/article/view/707 https://orcid.org/0000-0003-1723-6805 https://orcid.org/0000-0002-5071-2474 http://asianonlinejournals.com/index.php/arees/article/view/707 https://orcid.org/0000-0003-1723-6805 https://orcid.org/0000-0002-5071-2474 asian review of environmental and earth sciences, 2018, 5(1): 27-33 28 1. introduction the increasing growth of urban centres in most developing countries of the world in recent time has resulted in increased consumption of resources to meet the growing demands of urban populations and industry. this situation result in generation of large amounts of solid waste in cities [1]. all human activities generate one form of waste materials or the other which may not be of immediate use and hence constitutes waste that is ultimately released into the environment [2]. thus, waste is an inevitable byproduct of our daily activities. in the past, when human population was relatively small, solid waste issues were not a serious problem. however, with urbanization and growth of large conurbations, the challenges posed by solid waste are becoming enormous. solid wastes is made up of all the organic and inorganic waste materials that are usually non free flowing that is produced as a result of human and animal activities which have lost their value to the user and consequently discarded as useless or unwanted [3]. solid waste is one of the most visible, immediate and serious environmental problems facing most municipal authorities in developing countries [4]. consequently, this growing solid waste disposal challenges in developing countries is gradually approaching crises level. this trend of indiscriminate waste disposal has gone unchecked for so many years that the situation appears to be intractable. in nigeria, solid waste disposal problem is typified by overflowing dustbins, mountains of open refuse dumps at virtually every street and corners of the town; with their attendant problems (especially where burning occurs) and the existence of improperly operated landfills which are often rodent infested, with potentials for surface and ground water pollution [2]. the volume of solid waste generated in any urban centre is often a reflection of the intensity of human activities such as population, urbanization, social development, resource exploitation and unchecked technological advances. all these activities generate one form of waste or the other. the implication of this is that we have more solid waste to cope with than ever before [5]. poor disposal of solid waste has adverse effect on the environment in general [6]. the issue of solid waste generation and its likely effects on the health, quality of environment and urban landscape have become burning national issues in nigeria today. all stakeholders concerned with the safety of our environment have come to realize the negative consequences of mounting solid wastes found in residential neighborhoods, markets, schools, and central business districts in our urban centres. these solid wastes have become recurring features in our urban environment. there is no gainsaying that our urban centres today are full of problems associated uncleared solid wastes [7]. there is increasing trend of indiscriminate dumping of solid waste in jalingo town as in other major cities in nigeria. this increasing trend is further made worst by the prevailing incidence of poverty, population explosion, decreasing standard of living, poor governance and low level of environmental awareness [8]. the perception of one’s capability can be said to set a limit to what one can do and ultimately what could be achieved [9]. owing to challenges of improper management and lack of public awareness, some major part of jalingo town is heavily inundated with indiscriminate solid waste that constitutes health challenges to residents of the area. the environmental degradation and health impact of poor disposal of solid waste can be seen in the contamination of both surface and ground water through direct waste contacts, air pollution by burning of wastes, spreading of diseases by different vectors like birds, insects and rodents, or uncontrolled release of methane by anaerobic decomposition of waste [10]. the health implications of improper solid waste disposal are enormous and cannot be ignored. solid wastes that are not properly managed can cause water pollution which may breed diseases like cholera, typhoid and others. indiscriminate disposal of solid waste is a threat to human health. inadequate disposal of solid waste is a major factor in the spread of gastrointestinal and parasitic diseases primarily caused by vectors. at the moment, there is need to increase the level of awareness of the effects of poor solid waste disposal among residents in the town especially as it relates to open dumping of solid wastes and water pollution. this study examines the level of awareness and perception of the effect of poor waste disposal among residents of the study area. 2. materials and methods data for the study were collected through direct observation and use of structured and semi-structured questionnaire and interview methods. the questionnaires were used to obtain the residents views and ideas about waste generation and disposal methods in the study area. the questionnaire contains 25 questions that focused on knowledge of what constitutes waste, effective methods of waste disposal, poor waste disposal methods, health impacts of poor waste disposals, environmental pollution from improper waste disposal and problems associated with open dump sites among others. some waste dumpsites were visited in the selected wards. this affords the researcher the opportunity to see how wastes are disposed in the study area. data were collected during the period from november to december 2017. one hundred and two (102) people were selected through simple random sampling technique. five political wards (barade, majidadi, sintali a, turaki a and turaki b) were purposively selected from the ten political wards in the study area because of the high population density, presence of poorly planned residential houses and proliferation of open waste dumps in the area. the data were analyzed using descriptive statistics. asian review of environmental and earth sciences, 2018, 5(1): 27-33 29 figure -1. map of jalingo lga showing sampled wards source: data analysis 3. results of findings 3.1. demographic characteristics of respondents results of findings demographic characteristics of respondents the demographic data shows that 52% of the respondents are male and 48% are female as shown in table 1 below. the demographic data also shows that 43.1% are below the ages of 24 years, 22.6% are between 25–29 years, 15.7% between30-34years, 3.9% between 35-39 years and 5.9% are between the ages of 40-44years and 8.8% are above 45years. age composition is important in order to ensure that participants were old enough to understand wastes and environmental issues [11]. the result also shows that 58.8% of the respondents are married, 35.3% are single, 3.3% are widowers,1% widow and 1% are separated. in terms of occupation, 35.3% were unemployed, 31.4% are civil servants14.7% are farmers, 4.9% artisans and 2.9% retired. according to bogoro, et al. [6] the type of occupation does not only influence the type and amount of solid wastes generation, it also affects the waste disposal practices. table-1. demographic characteristics of respondents gender gender frequency percentage (%) male 53 52 female 49 48 total 102 100 age less than 24years 44 43.1 25 – 29yrs 23 22.6 30 – 34yrs 16 15.7 35 – 39yrs 04 3.9 40 44yrs 06 5.9 45yrs and above 09 8.8 total 102 100 marital status married 60 58.8 single 36 35.3 widow 04 3.9 widower 01 1.0 separated 01 1.0 total 102 100 education no formal education 39 38.3 primary education 23 22.5 secondary education 24 23.5 tertiary education 16 15.7 total 102 100 occupation farmer 15 14.7 artisan 05 4.9 retired 03 2.9 unemployed 36 35.3 civil servant 32 31.4 others 11 10.8 total 102 100 source: fieldwork, 2017. asian review of environmental and earth sciences, 2018, 5(1): 27-33 30 from table 1, it can be seen that 37.3% of the respondents have not had formal education before, 32.3% of respondents are primary school certificate holder, 15.7% of the respondents have attended secondary school, while only 12.7% have been to tertiary educational institutions. one can infer from the result of the findings above that the educational status of most of the respondents is low. therefore, most of them may not have much awareness of the effects of poor solid waste disposal to their health and the environment. 3.2. waste generation and disposal in the study area the findings of the study show that the type of waste generated in the study area according to 37.3% of the respondents is garbage, 32.3% rubbish, trash 15.7%, and effluent 12.7% (table 2). table-2. type of waste generated in the study area s/no type of waste frequency percentage 1 garbage 38 37.3 2 rubbish 33 32.3 3 trash 16 15.7 4 effluent 13 12.7 5 total 102 100 source: fieldwork, 2017. most of the wastes are collected temporary for a short period of time before they are finally disposed off. the waste collection facilities according to respondent’s opinion are open waste bin (30.4%), close waste bin (50%), plastic bags (15.7%) and others 3.9% (table 3). when the wastes are collected, they are transported to the dumping sites. table-3. types of waste collection facilities s/no types of waste storage frequency percentage 1 open waste bin 31 30.4 2 close waste bin 51 50.0 3 close plastic bags 16 15.7 4 others 04 3.9 5 total 102 100 source: fieldwork, 2017. findings from the study shows that most of the waste (37.3%) were transported by trucks while 48% of the respondents claimed that the waste are transported to dumpsites manually on the head, and 11.8% claimed that waste are transported through waste van and 2.9% claimed other means (table 4). table-4. mode of transportation of waste s/no mode of transportation waste frequency percentage 1 manually on head 38 37.3 2 use of trucks 49 48.0 3 use of waste van 12 11.8 4 others 03 2.9 5 total 102 100 source: fieldwork, 2017. the solid wastes generated in jalingo metropolis can either come from residential premises (households), industries, markets, shops, offices (government and private), and municipal areas. wastes collected from the residential premises are either sent to the community collection centers (temporary dumpsites) or taken directly to the main disposal site (located in the area). households often accumulate wastes outside their houses in plastic bags (cement bags, fertilizer bags and small plastic bags). the methods of waste disposal in the study area according to the respondent’s opinion include open waste bin 54%, open dumpsites 33.3%, burying in landfills 8.8% and others 3.9% as shown in table 5. table-5. method of waste disposal s/no method of waste disposal frequency percentage 1 use of waste bin 55 54.0 2 open dumpsites 34 33.3 3 burying in landfills 9 8.8 4 others 4 3.9 5 total 102 100 source: fieldwork, 2017. 3.3. causes of improper waste disposal when the respondents were asked the causes of poor waste disposal in the study area, 39% of the respondents attributed it to indifferent attitude of the residents in the study area, 35% of the respondents claimed it is the lack of waste disposal facilities, 22% lack of waste services and 6% to institutional failure (table 6). table-6. causes of poor waste disposal s/no causes of poor waste disposal frequency percentage 1 lack of waste service 22 21.6 2 indifferent attitude of residents 39 38.2 3 lack of waste disposal facilities 35 34.3 4 institutional failure 06 5.9 5 total 102 100 source: fieldwork, 2017. asian review of environmental and earth sciences, 2018, 5(1): 27-33 31 findings from the study shows that most of the waste generated in the town come from residential households, market places, business shops, government and private offices and municipal areas. most of the waste generated are either disposed off the street or any nearby dumpsite (mostly unapproved and illegal). abul [12] identified 6 approved dumpsites and 92 unapproved dumpsites in the study area. findings from field observation show the presence of few movable waste disposal containers located in some few wards and streets in the study area. 3.4. awareness and perception of effects of poor waste disposal when the respondents were asked if they know what constitute poor waste disposal, 24.5% claimed that it is pouring of effluent on the street, 22.5% claimed that it is dropping rubbish randomly, 44.2% claimed that it is dumping refuse in open dumps, while 8.8% claimed that it is burning of waste materials in open space (table 7). table-7. description of poor waste disposal s/no description of poor waste disposal frequency percentage 1 pouring of effluent on the street 35 24.5 2 dropping of rubbish randomly 23 22.5 3 dumping of refuse in open dumps 45 44.2 4 burning of waste materials 11 8.8 5 total 102 100 source: fieldwork, 2017. it has been observed that indiscriminate dumping of solid waste has become a common practice in most urban centres in nigeria. the increasing rate of this practice is attributed to increasing urbanization, rapid population growth, deterioration in standard of living, poor governance and low level of public awareness of the effect of indiscriminate waste disposal among others. findings from the study shows that 92% of the respondents claimed that they are aware of the effects of poor waste disposal while 8% claimed that they are not aware of the effects of poor waste disposal. on the description of waste disposal method in the study area by the respondents, 45.1% claimed that their present practice is safe, 12.7% claimed it is environmentally friendly, 36.3% insist it is environmentally harmful and 5.9% claimed that they don’t know (table 8). table-8. description of efficiency of waste disposal methods in the study area s/no description of efficiency of waste disposal frequency percentage 1 very safe 46 45.1 2 environmentally friendly 13 12.7 3 environmentally harmful 37 36.3 4 don’t know 06 5.9 5 total 102 100 source: fieldwork, 2017. on the effects of poor waste disposal, 44.1% of the respondents claimed that it is associated with offensive odour, 18.6% claimed that it is a breeding ground for insect parasites, 8.8% believed that it affects the aesthetic quality of the environment, 5.9% claimed it blocked drainages and 17.7% claimed that it caused health problems (table 9). table-9. effects of poor waste disposal s/no effects of poor waste disposal frequency percentage 1 offensive odour 45 44.1 2 breeding ground for parasites 19 18.6 3 eyesore 09 8.8 4 aesthetic problem 05 4.9 5 blockage of drains 06 5.9 6 health problems 18 17.7 7 total 102 100 source: fieldwork, 2017. ebikapade, et al. [11] findings show that the more the public are informed on waste management matters, the better their perception and attitude towards environmental issues. the finding which was consistent with the findings of rahardyan, et al. [13] shows that publicity increases awareness, and with increased awareness; residents are better disposed to participating in waste management in their community. 3.5. waste management in the study area the study sought to find out if there is any waste management policy in existence. 49% of the respondents claimed that there is waste management policy in place while 51% of the respondents claimed there was none in existence. on the existence of community participation in waste management, 68% of the respondents claimed that there is while 32% claimed that there is none. when asked to suggest efficient method of waste management in the study area, 57% suggest waste recycling, 24% claimed that it is burying in public landfills, 19% suggest incinerators and 2% suggest other methods (table 10). asian review of environmental and earth sciences, 2018, 5(1): 27-33 32 table-10. efficient methods of waste management s/no efficient methods of waste management frequency percentage 1 recycling of waste 57 2 incineration 19 3 burying in public landfill 24 4 others 02 5 total 102 source: fieldwork, 2017. 66% of the respondents claimed that they adopt waste minimization strategy and 36% claimed that they don’t. also, 52% of the respondents claimed that the segregate the waste materials before disposal while 48% claimed that they don’t segregate the waste before disposal. 4. discussion of findings the increase in waste generation in most urban centres in nigeria in recent times has risen astronomically as a result of urbanization and industrialization. effective waste management has become an intractable problem beyond the capacity of most municipal authority in most developing countries. effective solid waste disposal has become one of the challenges of urban centres in contemporary times that have defied all solutions by both state and federal government and non-governmental organizations. the increasing population in urban areas has outstripped the weak and inadequate infrastructure for waste management, resulting in refuse heaps that is left only to burning method and exposures to open landfills adejobi and olorunnimbe [5]. abd’razack, et al. [14] observed that many parts of jalingo town especially the central business districts do not benefit from any organized waste management services. solid wastes are usually unattended to, and in some cases either buried or burnt without taking into consideration the effects on the environment. due to poor management and lack of public awareness, many parts of jalingo metropolis is littered with solid waste which constitutes health hazards to the general public. other causes of poor solid waste disposal in the study area include lack of good and enough infrastructures, non-implementation of existing environmental sanitation laws and regulations, irregular and unplanned dumping of solid wastes, population growth due to rural-urban migration, insufficient capital to manage solid waste and lack of new technology in effective solid waste disposal [7]. moreover, lack of awareness and active involvement of the households as key stakeholders in service provision and unwillingness to pay for solid waste collection and disposal in the study area contributes to poor solid wastes disposal in the area. the most common solid waste disposal method in the study area is open dumpsites. however, open dumpsites are good sources of environmental pollution (polluting soil, ground and surface water) due to the fact that they usually contain almost all types of pollutants from the initial collection sources [15, 16]. open dumping of food wastes results in various environmental and health hazards. the decomposition of organic materials produces methane, which can cause fire and explosions and contributes to global warming [5]. this health hazards can include contamination of surface and ground water through direct waste contacts or leachate, air pollution by burning of wastes, spreading of diseases by different vectors like birds, insects and rodents, or uncontrolled release of methane by anaerobic decomposition of waste. thus, inadequate collection and improper waste disposal facilitates multiplication of pathogens causing diseases like cholera and diarrhea and provides favourable breeding ground for disease vectors like mosquitoes (malaria), flies (diarrhea) and rodents [12, 17]. proper solid waste disposal is a big problem in most urban centres especially in developing countries and sub saharan africa in particular. the intensity of solid waste management problem increases with increased population resulting from increased human activities and the volume of solid wastes to be disposed. industries and urban municipal areas generate large amount of solid wastes that are often dumped in open field. the safe alternative to open dumpsites which is sanitary landfill, is a site where wastes are disposed at a carefully selected location constructed and maintained by means of engineering techniques that minimize pollution of air, water and soil, as well as other risks to humans and animals. loans or grants to construct sanitary landfills do not necessarily result in sanitary landfill disposal [5]. unlike other larger urban centres in nigeria where government agencies and officials move from house to house to collect solid waste from households, there is no such arrangement in jalingo town. there are no private firms that are engaged in waste collections. this may be attributed to the low level of willingness to pay for such services as a result of the low value placed on solid waste disposal in the study area. this is further made worst by the lack of sanitary health workers that in the past, move from house to house, shops and business areas to enforced sanitary regulations in the town. the monthly compulsory sanitation usually observed by residents in the town in the early hours (0700 to 1000hrs) of last saturday of the month is no longer operational. casual workers that were employed to cleanup major streets and institutional areas in the town have quit the job because of many years of unpaid wages. 5. conclusion this study has examined the level of public perception and awareness of the effects of poor solid wastes disposal in jalingo metropolis. although jalingo is not an industrial town, increase in population over the years has led to increasing rate of urbanization with the attendant problem of indiscriminate solid waste disposal. from the study, 39% of the respondents attributed the causes of poor waste disposal to indifferent attitude of the residents, 35% to lack of waste disposal facilities, 22% lack of waste services and 6% to institutional failure. the findings show that most of the wastes generated in the town come from residential households, market places, business shops, government and private offices and municipal areas. most of the wastes are either disposed of the street or any nearby dumpsite (mostly unapproved and illegal). most of the respondents claimed to be aware of what constitutes solid waste and effects of poor disposal. however, this claim negates attitude of indiscriminate solid waste disposal asian review of environmental and earth sciences, 2018, 5(1): 27-33 33 in the study area as revealed by the increasing number of open waste dumpsites and wastes that litters most streets of the town. solid waste generated by the daily activities of the people needs to be properly managed in such a way that it minimizes the risk to the environment and human health. 6. recommendations based on the findings of this study, the following recommendations are suggested; i. increase enlightenment campaign through jingles in mass media. ii. recruitment and empowerment of community health workers and sanitary officers. iii. reactivation of the monthly environmental sanitation programme references [1] k. boadi and m. kuitunen, "environmental and health impacts of household solid waste handling and disposal practices in third world cities: the case of the accra metropolitan area, ghana," journal of environmental health, vol. 68, p. 32-37, 2005. [2] i. abdullahi, m. a. ajibike, a. p. man-ugwueje, and o. i. ndububa, "environmental impact of indiscriminate waste disposal a case study of nigerian air force base kaduna," international journal of engineering and applied sciences, vol. 1, pp. 25-33, 2014. [3] a. chengula, b. k. lucas, and a. mzula, "assessing the awareness, knowledge, attitude and practice of the community towards solid waste disposal and identifying the threats and extent of bacteria in the solid waste disposal sites in morogoro municipality in tanzania," journal of biology, agriculture and healthcare, vol. 5, pp. 54-65, 2015. [4] m. m. rahman and m. a. ali, "waste management and environmental pollution in bangladwsh," presented at the intl conf. bangladesh environ., icben, buet, dhaka, bangladesh, 2000. [5] o. adejobi and r. olorunnimbe, "challenges of waste management and climate change in nigeria: lagos state metropolis experience," african journal of science and research, vol. 7, pp. 346-362, 2012. [6] a. bogoro, y. mohammed, and y. yakubu, "indiscriminate solid waste disposal in bauchi: causes and impacts on the community and environment," journal of environment and earth science, vol. 3, pp. 40-54, 2013. [7] n. s. momodu, k. o. dimuna, and j. e. dimuna, "mitigating the impact of solid wastes in urban centres in nigeria," journal of human ecology, vol. 34, pp. 125-133, 2011.available at: https://doi.org/10.1080/09709274.2011.11906377. [8] o. a. rachel, h. komine, k. yauhara, and s. murakami, "municipal solid waste management in developed and developing countries: japan and nigeria as case studies," solid waste audit report. federal capital territory, abuja nigeria 20042009. [9] c. i. holland and m. j. rosenberg, attitude organization and change. new haven: yale university press, 1996. [10] b. sarker, s. sarker, m. islam, and s. sharmin, "public awareness about disposal of solid waste and its impact: a study in tangail pourashava, tangail," journal of environmental science and natural resources, vol. 5, pp. 239-244, 2012.available at: https://doi.org/10.3329/jesnr.v5i2.14821. [11] a. ebikapade, j. a. t. omagbemi, and a. h. syed, "analysis of public participation in sustainable waste management practice in abuja, nigeria," environmental management and sustainable development, vol. 4, pp. 180-193, 2015.available at: https://doi.org/10.5296/emsd.v4i1.7269. [12] s. abul, "environmental and health impact of solid waste disposal at mangwaneni dumpsite in manzini: swaziland," journal of sustainable development in africa, vol. 12, pp. 64-78, 2010. [13] b. rahardyan, t. matsuto, y. kakuta, and n. tanaka, "resident's concerns and attitudes towards solid waste management facilities," waste management, vol. 24, pp. 437-451, 2004.available at: https://doi.org/10.1016/j.wasman.2003.11.011. [14] n. t. a. abd’razack, a. e. yusuf, and j. z. utange, "an appraisal of solid waste generation and management in jalingo city, nigeria," journal of environment and earth science vol. 3, pp. 20-30, 2013. [15] g. r. kassenga and s. e. mbuligwe, "impacts of a solid waste disposal site on soil, surface water and groundwater quality in dar es salaam city, tanzania," journal of sustainable development in africa, vol. 10, pp. 73-94, 2009. [16] s. omofonmwan and j. eseigbe, "effects of solid waste on the quality of underground water in benin metropolis, nigeria," journal of human ecology, vol. 26, pp. 99-105, 2009.available at: https://doi.org/10.1080/09709274.2009.11906171. [17] s. m. kassim and m. ali, "solid waste collection by the private sector: households’ perspective—findings from a study in dar es salaam city, tanzania," habitat international, vol. 30, pp. 769-780, 2006.available at: https://doi.org/10.1016/j.habitatint.2005.09.003. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 55 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 55-60, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi:10.20448/journal.506.2020.71.55.60 © 2020 by the authors; licensee asian online journal publishing group design of a wastewater treatment oxidation pond oyati e. n1 olotu yahaya2 gimba i.n3 ibrahim rasheed4 ( corresponding author) 1department of civil engineering technology, auchi polytechnic, auchi, nigeria. 2,4department of agricultural and bio-envi. engineering, auchi polytechnic, auchi, nigeria. 3department of mineral and petroleum resources engineering, auchi polytechnic, auchi, nigeria. abstract the proposed site of the wastewater treatment pond is located in a terrain inside the polytechnic campus and the new staff quarters where the storm-runoff flow has on effect. the site possesses good soil characteristics which include a particle size distribution of sandy soil with little fine particles of gravel, a specific gravity of 2.77 and a soil moisture content of 7.26% indicating a high degree of permeability. the output of geotechnical analysis indicated that the proposed site has soil particle density (ρs) and dry bulk density (ρb) of 1.76 g/cm3 and 1.64g/cm3 respectively. void ratio (e), porosity (ȵ) values of 0.87 and 0.46 (46%) were determined. the atterbergs limits of 19.0%, 14.96% and 19.6% for shrinkage limit (sl), plastic limit (pl) and liquid limit (ll) were estimated with a computed plastic index (pi) of 3.04. the soil profile formation is highly sandy with a good lateritic layer to support the pond foundation. the proposed pond design volume (v) is 898.5 m3 and land areas of 718.8 m2 were estimated for the project. keywords: soil, density, limit, pond, permeability, wastewater, gravel, atterbergs limit. citation | oyati e. n; olotu yahaya; gimba i.n; ibrahim rasheed (2020). design of a wastewater treatment oxidation pond. asian review of environmental and earth sciences, 7(1): 55-60. history: received: 10 february 2020 revised: 12 march 2020 accepted: 14 april 2020 published: 4 may 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 56 2. materials and methods ................................................................................................................................................................... 56 3. results and discussion ................................................................................................................................................................... 59 4. conclusion ......................................................................................................................................................................................... 59 references .............................................................................................................................................................................................. 59 https://www.asianonlinejournals.com/index.php/arees/article/view/1578 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.55.60&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2020, 7(1): 55-60 56 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the proposed site of the wastewater treatment pond is located in a terrain inside the polytechnic campus and the new staff quarters where the storm-runoff flow has on effect. 1. introduction the treatment of wastewater using the interaction of bacteria, algae, and sunlight inside shallow confinement known as oxidation pond is one of the techniques of wastewater treatment. the essence of treating wastewater and effluent using the oxidation pond is basically structured to reduce and remove the pathogens and organic matters contained in wastewater. the wastewater stabilization pond has numerous advantages such as adequate treatment compartments, accurate balancing of temperature and other parameters as dissolved oxygen (do), nutrient and organic matters [1-3]. oxidation pond is made of a set of organisms associated together such as algae, fungi, viruses, and fungi. the biodegradable organic matter (bod) is decomposed by the bacteria and carbon dioxide, nitrates and ammonia are released [4]. the oxidation pond could be designed to treat different categories of effluent ranges from industrial wastewater to municipal wastewater [5]. the naturally-based wastewater stabilization pond requires a large surface area for its construction. oxidation pond is less scientifically-based with the design of 0.6 m to 1.6 m depth [2]. effluents from oxidation are usually applied for irrigation and aquaculture agriculture. also, stabilization ponds are commonly used in regions with warm to mild climate throughout the year [6]. the removal of suspended solids (ss) and organic matter is the initial stage of treatment in the anaerobic, the secondary stage takes place in a facultative pond where the remaining organic matter is removed using the simulated heterotrophic and activated algae mara and pearson [4]. erick, et al. [1] reported that aerobic ponds are suitable for high biochemical oxygen demand (bod) removal and ideal for areas where the cost of land is not expensive. the new staff quarters of auchi polytechnic, auchi could adopt this mechanism for its wastewater treatment. it has been observed that most of the septic tanks and soak-away pits in the new staff quarters are no longer effective due to an increase in wastewater generation. hence, the objective of the present study was to design a wastewater oxidation pond at auchi polytechnic, new staff quarters that will be useful to treat wastewater effluent; having considered the suitability factors such as the intensity of temperature and sunlight for removal processes. oxidation ponds are also productive because it generates effluent that can be used for other applications such as fertilizer and pilet for arable and fish farming. 2. materials and methods 2.1. design considerations four significant mechanisms (interception, gravity, advection and diffusion) are included in oxidation pond. the pond is designed to be at least 150 m from residential houses and the treated effluent would be constantly diluted of discharge. soils and parent materials at site must be impermeable to pond waters as the waste solution can contaminate ground water if seepage occurs. the following considerations were made as follows: the aerobic pond should be sited in an open area for interception of solar radiation and wind; the storm water catchment needs to be kept to a minimum to increase the retention time of ponds; rainwater run-off from the roof building would be channeled away from the effluent system; technical pipeline laying system; and creation of accessibility for earth moving equipment. the designed ratio of width to length is 1:2. this process ensures that the effluent remains within the system for a required period of time. the oxidation stabilization width is designed for effective workability of excavators and desludging machinery, the design of 0.5 m for the freeboard is allowed for slurry and sedimentation. figure 1 and figure 2 show the dimensional views of the designed oxidation pond, while figure 3 shows the oxidation operational system of wastewater treatment pond. figure 4 and figure 5 show the oxidation pond system and application of its by-product (sludge) for cropland farming. figure-1. front view of proposed oxidation pond. source: mara and pearson [4]. asian review of environmental and earth sciences, 2020, 7(1): 55-60 57 © 2020 by the authors; licensee asian online journal publishing group figure-2. oxidation pond and processes. source: ramandan and ponce [7]. figure-3. wastewater treatment arrangement in oxidation pond. source: ramandan and ponce [7]. figure-4. oxidation pond treatment system. source: alexiou and mara [8]. figure-5. application of fertilizer value of oxidation pond treatment system for cropland. source: alexiou and mara [8]. asian review of environmental and earth sciences, 2020, 7(1): 55-60 58 © 2020 by the authors; licensee asian online journal publishing group 2.2. design calculations the proposed oxidation pond was designed to achieve 65% removal of biodegradable organic matter at about 20oc structured at 300 mg/l; temperature below 15oc causes the digestion processes to slow down with large sedimentation [4]. the chemical processes taking place in the anaerobic pond is represented in equations 1-3: (1) (2) (3) there is strong relationship between wastewater generation and population growth; therefore, population growth-projection and oxidation pond volume were calculated using equation 4. (4) where: v is the volume of the oxidation pond in cubic meter, the effluent flow rate is q in m3/s, the biodegradable organic matter (bod) is la, the pond temperature and temperature coefficient in t and θ; the sulfide oxygen, algal toxicity factor are represented as ff1 [9]. equation 5 was applied to project the population of the new staff quarters in auchi polytechnic, auchi for the next 20-year (5) where, po = present population = 250 people. r = growth rate = 2.8 %. t = design period = 20 years. pt = projected population. pt = 250 (1 + 0.028)20. pt = 434.3 = 435 people. the initial treatment stage in stabilization pond is by introducing high volumetric organic matter of biodegradable (bod) higher than 100g of bod5/m3. however, the volumetric loading is equated using equation 6. as follows: (6) where: influent of biodegradable organic matter (bod), influent flow rate (q) m3/d and the volume of oxidation pond (m3). using the retention time, volumetric loading is computed from equations 7-8. (7) where: (8) maximum surface organic loading (msor) and ambient air temperature of the coldest period is equated using the expression in equation 9: (9) where:  s = surface organic loading, kg bod5/ha.d t = mean ambient air temperature of coldest month, °c. archer [10] showed that the formula was designed for surface loading rate due to its suggestion of the agreement with available operating data, including a factor of safety of about 1.5, as represented in equation 10. (10) in the facultative pond, the hydraulic retention time (tf) is estimated using equation 11 (11) af is the area of the stabilization pond; and df is the pond diameter. the following assumptions were considered in the design: i. bod5 conversion = 905. ii. bod5 removal rate = 0.36/day at 200c. iii. temperature coefficient = 1.06 at 200c. iv. pond temperature; (a).warmth 350c ( b). cold 250c. v. maximum pond depth = 1.25 m vi. dispersion factor of ponds = 1.0 2.2.1. sewer design the average generated sewage from the community is 87.0 m3/day estimated using the equation 12. (12) where, qd is generated sewage; pt is the projected population; pcd is water consumed and sw is spent. when the sewer is flowing at 1/6 full-flow capacity, the velocity of flow (v) is estimated to be 0.3 m/s using manning formula as shown in equation 13. figure 6 indicates a partially filled section of a flow flowing in a circular pipe. d is the diameter of the pipe, while (h) depth of water in the pipe. asian review of environmental and earth sciences, 2020, 7(1): 55-60 59 © 2020 by the authors; licensee asian online journal publishing group figure-6. partially filled section of a flow flowing in a circular pipe. source: ramandan and ponce [7]. (13) where, n ranges from 0.013-0.015. therefore, the depth of flow from the circular channel was calculated using the expression in equation 14. (14) q is the effluent flowrate; n is the manning coefficient of friction; h is depth of flow; s is the slope and d is diameter of conduit. the area of the pipe was determined using continuity equation as shown in equation 15. where v = 0.3m/s for a sewer flowing 1/6 full (15) diameter of the effluent conveying pvc pipe was calculated using equation 16. (16) 3. results and discussion new staff quarters of auchi polytechnic is a residential compound in the polytechnic within the auchi community with an estimated population equal to 250 people and a projected population of 485 people. the detailed results of the designed oxidation pond variables, geotechnical parameters, and wastewater analysis were well-validated. the projected population for new staff quarters for the next 20-year is 435 people. the soil is sandy with little fine particles of gravel. it has a bulk density (ρbulk) and particle dry density (ρdry) of 1.76g/cm3 and 1.64 g/cm3. the degree of saturation (ȵ), void ratio (e), moisture content (m.c) and a specific gravity of 91.4%, 0.87, 0.46 and 2.77 respectively. oxidation surface pond area and volume of 723.8m3 and 898.5m3 were designed. detention times (tan) at 25oc and 35oc were estimated to 6-day and 10.4 days respectively. using the standard method, design load of less and not more than 350 bod/m3d for the dry season. however, the design consideration of 120 bod/m3d and temperature range of 10oc-13oc was applied to maintain odour challenges. the volumetric loading and sulfate concentration were applied using the procedure of alexiou and mara [8]. the effluent from municipal oxidation pond is designed to have bod5 between 60 and 75 mg/l and this is in line with world health organization (who) standard. it is deduced from the study that cod design variables for stabilization pond could be applied to replaced bod. the dilution would be in the order of 7:1, and the living algae continues contains in the effluent becomes very useful due to its photosynthetic processes. 4. conclusion the design apparatus has indicated that the oxidation pond would be very suitable for wastewater treatment at the new staff quarters at auchi polytechnic, auchi due to its inexpensiveness in design and construction. also, the climatic conditions in auchi highly favored the development of the wastewater stabilization pond. the reuse of the treated effluent will subsequently reduce the water pressure. conversely, temperature, retention time and volumetric loading greatly affect organic loading and efficiency in the oxidation pond. references [1] b. erick, t. young, and a. a. mohammed, "oxidation pond for municipal wastewater treatment," appl water science, vol. 4, pp. 440-445, 2015. [2] b. b. hosetti and s. frost, "a review of the sustainable value of effluents and sludges from wastewater stabilization ponds," ecological engineering, vol. 5, pp. 421-431, 1995. available at: https://doi.org/10.1016/0925-8574(95)00005-4. [3] c. amengual-morro, g. m. niell, and a. martínez-taberner, "phytoplankton as bioindicator for waste stabilization ponds," journal of environmental management, vol. 95, pp. s71-s76, 2012. available at: https://doi.org/10.1016/j.jenvman.2011.07.008. [4] d. mara and h. pearson, design manual for waste stabilization ponds in mediterranean countries. leeds: lagoon technology international ltd, 1998. [5] d. g. rose, community-based technologies for domestic waste water treatment and reuse options for urban agriculture, (cities feeding people (cfp) report series 27). ottawa: international development research center canada (idrc), 1999. [6] m. i. badawy, r. a. el-wahaab, a. moawad, and m. e. ali, "assessment of the performance of aerated oxidation ponds in the removal of persistent organic pollutants (pops): a case study," desalination, vol. 251, pp. 29-33, 2010. available at: https://doi.org/10.1016/j.desal.2009.10.001. [7] m. ramandan and v. m. ponce, "design and performance of waste stabilization pond," historical hyrological, vol. 2, pp. 13-42, 1999. [8] g. alexiou and d. mara, "anaerobic waste stabilization ponds," applied biochemistry and biotechnology, vol. 109, pp. 241-252, 2003. asian review of environmental and earth sciences, 2020, 7(1): 55-60 60 © 2020 by the authors; licensee asian online journal publishing group [9] b. a. finney and e. j. middlebrooks, "facultative waste stabilization pond design," journal (water pollution control federation), vol. 23, pp. 134-147, 1980. [10] j. p. archer, notes on the design and operation of waste stabilization ponds in warm climates of developing countries. washington: the world bank, 2011. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 10 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 10-17, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.10.17 © 2021 by the authors; licensee asian online journal publishing group analytic hierarchy process–based environmental criteria weight assessment and prioritization for suitable petroleum refining plant siting in edo state, nigeria aweh d.s.1 igbokwe j. i.2 ejikeme, j.o.3 ( corresponding author) 1department of surveying and geoinformatics, nnamdi azikiwe university, awka, nigeria & department of surveying and geoinformatics, auchi polytechnic, auchi, nigeria. 2,3department of surveying and geoinformatics, nnamdi azikiwe university, awka, nigeria. abstract in this paper, saaty’s analytical hierarchy process (ahp) of multi-criteria evaluation (mce) technique was used to estimate the weights of some selected environmental criteria in the suitable siting of a petroleum refining plant. in doing this, fifteen (15) key environmental criteria, based on reviewed literature, specifications, and environmental impact assessment act (eia) on the siting of petroleum refining plants were selected for this study, which includes ground water level, proximity to major settlement, proximity to water bodies, proximity to the electricity transmission line, land use / land cover, topography, sensitive and protected areas proximity, critically polluted areas (refuse dumpsites, landfill sites, etc.), proximity to existing industrial areas, major transportation network, flood zones, proximity to crude oil supply (oil well), wind speed, large-scale mines and population density. the result from the calculated environmental criteria weights show proximities of petroleum refinery to existing industrial areas; source of crude oil and landuse/landcover to have the highest influence value, followed by proximity to water body; population density; groundwater level; major settlement; wind speed; transportation network, topography, while sensitive/protected areas, critically polluted areas and flood zones with the least influence value. the result of this ahp – based weight assessment will be used generally by planners, investors, environmental managers, and oil and gas experts as a general guide in the prioritization of criteria weights based on the influence of one criterion over the other in the suitability siting of petroleum refining plant. keywords: criteria weight, site selection, ahp-based mce, petroleum refinery, edo state. citation | aweh d.s., igbokwe j. i., ejikeme, j.o. (2021). analytic hierarchy process–based environmental criteria weight assessment and prioritization for suitable petroleum refining plant siting in edo state, nigeria. asian review of environmental and earth sciences, 8(1): 10-17. history: received: 22 january 2021 revised: 26 february 2021 accepted: 18 march 2021 published: 20 april 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 11 2. materials and methods ................................................................................................................................................................... 11 3. result and analysis .......................................................................................................................................................................... 16 4. conclusion ......................................................................................................................................................................................... 17 references .............................................................................................................................................................................................. 17 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2021.81.10.17&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/2817 asian review of environmental and earth sciences, 2021, 8(1): 10-17 11 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature in this paper, saaty’s analytical hierarchy process (ahp) of multi-criteria evaluation (mce) technique was used to estimate the weights of some selected environmental criteria in the suitable siting of a petroleum refining plant. 1. introduction the petroleum industry provides most of the needed fuel for everyday use for industrial, commercial, and domestic purposes. in fact, modern industrial civilization depends on petroleum and its products; the physical structure and way of life of the suburban communities that surround the great cities are the result of an ample and inexpensive supply of petroleum [1, 2]. in addition, the goals of developing countries to exploit their natural resources and to supply foodstuffs for the burgeoning populations are based on the assumption of petroleum availability. most of the world’s supply of petroleum comes from the middle east, nigeria, angola, libya, etc. [36]. despite this monumental projected importance of modular petroleum plants in remedying unemployment and economic issues, the adverse impact of these modular refineries on their immediate environment and beyond cannot be underemphasized. therefore, stakeholders should be fully aware of these implications and should take necessary steps while setting up industries so as to minimize the possible adverse effects on environmental resources and quality of life, through careful selection and assessment of identified criteria [7]. the identification of a suitable site for industrial development is one of the critical issues in the process of planning, starting, expanding, or changing the location of industrial systems of all kinds [8]. one of the main objectives in industrial site selection is finding the most appropriate site with desired conditions defined by the selected criteria. in a site selection process, the analyst strives to determine the optimum location that would satisfy specified conditions which is a direct determinant of the influence level (weight) of the selected criteria. the most frequently raised problem in mce is how to establish weights for a set of activities according to importance mohamed, et al. [9]. saaty [10] has shown that this weighting of activities in mce can be dealt with using a theory of measurement in a hierarchical structure. the analytic hierarchy process (ahp) is a comprehensive, logical, and structural framework, which allows improving the understanding of complex decisions by decomposing the problem in a hierarchical structure. the incorporation of all relevant decision criteria and their pairwise comparison allows the decision-maker to determine the trade-offs among objectives. such multi-criteria decision problems are typical for industrial site selection. the ahp allows decision-makers to model a complex problem in a hierarchical structure showing the relationship of the goal, objectives (criteria), sub-objectives, and alternatives [9]. uncertainties and other influencing factors can also be included. it does not only supports decision makers by enabling them to structure complexity and exercise judgment, but also allows them to incorporate both objective and subjective considerations in the decision process [10]. 2. materials and methods 2.1. study area the area selected for this study, edo state is in the south-south geopolitical zones of nigeria. edo is a state in southern nigeria. it was created on 27th august 1991 when the former bendel state (now edo and delta) was separated into these two states. edo state is located between latitudes 7°18'8.61"n to 5°52'48.77"n of the equator and longitudes 6°36'59.29"e to 5°12'58.38"e of the greenwich meridian, with a surface area of approximately 19,603 km2. its capital is benin city. with a population of 3,218,332 million people (2006 census). it is bounded in the north and east by kogi state, in the south by delta state, and in the west by ondo state. economically, edo state is more of a commercial and agricultural driven state. the majority of its population are either farmers or traders. there are various solid mineral deposits within the state such as; industrial clay, silica, lignite, kaolin, tar sand, decorative rocks, limestone, etc. still waiting to be properly used to their full potential. edo state also has deposits of crude oil and this makes it one of the petroleum-producing states in nigeria. figure 1, is the map of nigeria showing the study area (edo state) and the satellite image of edo state. 2.2. research instrument a total of one hundred (100) experts which consist of planners, oil and gas engineers, and geomaticians/environmentalists within edo state were proposed via a simple random sampling system. however, since the population is finite, it becomes imperative to apply a statistical model in determining the sample size. thus, yamane [11] formula was employed, at an acceptable level of probability of whose confidence level is set at 0.05 as displayed in equation 1. thus; n = 𝑁 1+𝑁(𝑒)2 (1) where; n = sample size e = level of significance (e = 0.05) n = population size (n= 100) 1 = constant applying the above formula, population size was computed as follows: n = 100 1+100 (0.05)2 n = 100 1+100 (0.0025) = 100 1.25 = 80 asian review of environmental and earth sciences, 2021, 8(1): 10-17 12 © 2021 by the authors; licensee asian online journal publishing group 2.3. selection of criteria based on reviewed pieces of literature and guidelines from relevant authorities, in this case, department of petroleum resources, nigerian national petroleum company, and environmental impact assessment act (eia) on the siting of petroleum refining plants, the following fifteen (15) criteria (factors/constraints) were identified and considered in this research. table 1 shows the criteria (factors/constraints) and the applied codes. figure-1. map of nigeria showing the study area (edo state) and the satellite image of edo state. asian review of environmental and earth sciences, 2021, 8(1): 10-17 13 © 2021 by the authors; licensee asian online journal publishing group table-1. criteria (factors / constraints) and codes used. s/n criterion ( input) factors/ constraints code 1 water bodies proximity factor mwb 2 electricity transmission line proximity factor etl 3 land use / land cover factor lulc 4 topography factor topo 5 sensitive and protected areas proximity constraint spa 6 critically polluted areas (refuse dump sites, landfill sites etc.) constraint cpa 7 proximity to existing industrial areas factor eia 8 transportation network factor mtn 9 flood zones constraint fz 10 raw material supply (crude oil) factor srm 11 wind speed factor ws 12 large-scale mines constraint lsm 13 population density factor pd 14 proximity to major settlement constraint ms 15 ground water level constraint gwl 2.4. pairwise comparisons the pairwise comparisons method was developed by saaty [10] in the context of the analytical hierarchy process (ahp). this method of criteria weight assessment involves pairwise comparisons to create a ratio matrix. as input, it takes the pairwise comparisons of the parameters in numerical form (i.e. on a scale of 1 to 9) and produces their relative weights as output. one (1) on the scale means that the two factors are equally important and 9 means that the one factor is absolutely more important than the other as shown in table 2. if a factor is less important than another then this is indicated by reciprocals of the 1 to 9 values (i.e.1/2 to 1/9). table-2. preferences made on 1-9 scale. numeric rating (judgment value) ahp scale of importance for comparison pair 9 extreme importance 8 very strong to extremely 7 very strong importance 6 strongly to very strong 5 strong importance 4 moderately to strong 3 moderate importance 2 equally to moderately 1 equal importance source: saaty [10]. 2.4.1. pairwise comparison matrix formation the pairwise matrix (table 3) was formed using the judgment value of comparison as the matrix elements and following the basic formation rules as established by saaty [10] and mohamed, et al. [9]. for example, the judgment value of mwb (lhs) against etl (rhs) is “6”, therefore, the matrix element in a cell, second roll, the third column (2, 3) is “6”; the judgment value of fz (lhs) against topo (rhs) is “3” therefore, the matrix element in a cell, tenth roll, fifth column (10, 5) is “3”; (i.e. 1/3), etc. table-3. pair-wise comparison matrix of the study. mwb etl lulc topo spa cpa eia mtn fz srm ws lsm pd ms gwl mwb 1.00 6.00 0.25 3.00 7.00 5.00 0.25 5.00 7.00 0.33 4.00 6.00 1.00 4.00 1.00 etl 0.17 1.00 0.11 0.33 1.00 2.00 0.11 0.50 2.00 0.11 0.33 1.00 0.17 0.50 0.17 lulc 4.00 9.00 1.00 6.00 9.00 8.00 1.00 7.00 9.00 1.00 6.00 8.00 3.00 7.00 3.00 topo 0.33 3.00 0.17 1.00 3.00 2.00 0.17 1.00 3.00 0.17 1.00 3.00 0.33 2.00 0.33 spa 0.14 1.00 0.11 0.33 1.00 1.00 0.11 0.25 1.00 0.11 0.25 1.00 0.17 0.50 0.17 cpa 0.20 0.50 0.13 0.50 1.00 1.00 0.11 0.33 1.00 0.11 0.33 1.00 0.20 0.33 0.20 eia 4.00 9.00 1.00 6.00 9.00 9.00 1.00 6.00 9.00 1.00 6.00 9.00 4.00 6.00 4.00 mtn 0.20 2.00 0.14 1.00 4.00 3.00 0.17 1.00 3.00 0.17 1.00 3.00 0.50 1.00 0.50 fz 0.14 0.50 0.11 0.33 1.00 1.00 0.11 0.33 1.00 0.11 0.25 1.00 0.20 0.33 0.20 srm 3.00 9.00 1.00 6.00 9.00 9.00 1.00 6.00 9.00 1.00 5.00 9.00 4.00 6.00 4.00 ws 0.25 3.00 0.17 1.00 4.00 3.00 0.17 1.00 4.00 0.20 1.00 4.00 0.50 1.00 1.00 lsm 0.17 1.00 0.13 0.33 1.00 1.00 0.11 0.33 1.00 0.11 0.25 1.00 0.17 0.25 0.25 pd 1.00 6.00 0.33 3.00 6.00 5.00 0.25 2.00 5.00 0.25 2.00 6.00 1.00 2.00 2.00 ms 0.25 2.00 0.14 0.50 2.00 3.00 0.17 1.00 3.00 0.17 1.00 4.00 0.50 1.00 1.00 gwl 1.00 6.00 0.33 3.00 6.00 5.00 0.25 2.00 5.00 0.25 1.00 4.00 0.50 1.00 1.00 total 15.85 59.00 5.12 32.33 64.00 58.00 4.97 33.75 63.00 5.09 29.42 61.00 16.23 32.92 18.82 basic rule: if the criterion in the column is preferred to the criteria in the row, then, the inverse of the judgment value is given, otherwise, the actual judgment value. note: the numbers represent expert judgment values of the importance of one factors in relation to other factors in the suitable siting of a modular refinery. 2.5. demonstration of satty’s ranking scale for judgment values asian review of environmental and earth sciences, 2021, 8(1): 10-17 14 © 2021 by the authors; licensee asian online journal publishing group by this judgment value, it means that siting the refinery in close proximity to major water bodies (mwb) is strongly important than its proximity to electricity transmission line (elt). by this judgment value, it means that topography (slope) is moderately important than proximity to flood zone (fz). by this judgment value, population density is slightly more important than major settlement. 2.6. computation of the criterion weights this involves the following operations; (a) formation of normalized pairwise comparison matrix. (b) formation of the prioritization weight matrix. 2.6.1. normalized pairwise comparison matrix formation the normalized pairwise comparison matrix was formed from the pairwise comparison matrix in table 4. here, the elements of the normalized matrix were formed by dividing the elements of each column by their sum total. for instance, the first element of the first column of the normalized matrix is computed thus; 1/15.85 = 0.06. where 1 is the first element of the first column of the pairwise comparison matrix and 15.85 is the sum total of its column. table-4. normalized pairwise comparison matrix. mwb etl lulc topo spa cpa eia mtn fz srm ws lsm pd ms gwl mwb 0.06 0.10 0.05 0.09 0.11 0.09 0.05 0.15 0.11 0.07 0.14 0.10 0.06 0.12 0.05 etl 0.01 0.02 0.02 0.01 0.02 0.03 0.02 0.01 0.03 0.02 0.01 0.02 0.01 0.02 0.01 lulc 0.25 0.15 0.20 0.19 0.14 0.14 0.20 0.21 0.14 0.20 0.20 0.13 0.18 0.21 0.16 topo 0.02 0.05 0.03 0.03 0.05 0.03 0.03 0.03 0.05 0.03 0.03 0.05 0.02 0.06 0.02 spa 0.01 0.02 0.02 0.01 0.02 0.02 0.02 0.01 0.02 0.02 0.01 0.02 0.01 0.02 0.01 cpa 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.02 0.01 0.02 0.01 0.01 0.01 eia 0.25 0.15 0.20 0.19 0.14 0.16 0.20 0.18 0.14 0.20 0.20 0.15 0.25 0.18 0.21 mtn 0.01 0.03 0.03 0.03 0.06 0.05 0.03 0.03 0.05 0.03 0.03 0.05 0.03 0.03 0.03 pfz 0.01 0.01 0.02 0.01 0.02 0.02 0.02 0.01 0.02 0.02 0.01 0.02 0.01 0.01 0.01 srm 0.19 0.15 0.20 0.19 0.14 0.16 0.20 0.18 0.14 0.20 0.17 0.15 0.25 0.18 0.21 ws 0.02 0.05 0.03 0.03 0.06 0.05 0.03 0.03 0.06 0.04 0.03 0.07 0.03 0.03 0.05 lsm 0.01 0.02 0.02 0.01 0.02 0.02 0.02 0.01 0.02 0.02 0.01 0.02 0.01 0.01 0.01 pd 0.06 0.10 0.07 0.09 0.09 0.09 0.05 0.06 0.08 0.05 0.07 0.10 0.06 0.06 0.11 pms 0.02 0.03 0.03 0.02 0.03 0.05 0.03 0.03 0.05 0.03 0.03 0.07 0.03 0.03 0.05 gwl 0.06 0.10 0.07 0.09 0.09 0.09 0.05 0.06 0.08 0.05 0.03 0.07 0.03 0.03 0.05 total 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 2.6.2. prioritization weight matrix formation in computing the element of this matrix, the normalized sum of each row is divided by the total number of its criteria. the obtained values (average) provides the relative weights of the criteria being compared as described in the studies by permadi [12] and odell [4]. for instance, the criteria weight of major water bodies (mwb) in this can be obtained thus; 0.06 + 0.10 + 0.05 + 0.09 + 0.11 + 0.09 + 0.05 + 0.15 + 0.11 + 0.07 + 0.14 + 0.10 + 0.06 + 0.12 + 0.05 (sum of the elements in first row) = 1.35 total number of criteria in first row = 15 therefore, the weight of major water bodies (mwb) = 1.35/15 = 0.09 weight of the criteria in percentage = 0.09 x 100 = 9% 2.6.3. consistency ratio check in checking the reliability of the respondent’s judgments, the consistency ratio (cr) for the judgment values provided by the consulted experts were calculated. according to saaty [10] if this ratio is found to be less than 10% (cr< 0.1) then the respondent judgment is consistent if otherwise (i.e. cr> 0.1) then the expert or respondent judgment is not consistent. calculating the consistency ratio of a judgment involves the following operations: formation of the weight as factor matrix by introducing the weights of the criteria as the first row of the matrix of comparison. calculation of the weighted column and weighted sum (consistency vector) by multiplying matrix of comparisons by the vector of priorities (corresponding weights) to get a new column vector. calculation of the average value of the consistency vector by dividing the first component of a new column vector (first element of the weighted sum matrix) by the first component of priorities vector (first element of the weight matrix), the second component of new column vector by the second component of priorities vector, and so on. calculation of the consistency index by adding up all the elements of the consistency vector (λ max) and applying the mathematical expression ci = (λ-n) / (n-1) where n is the total number of criteria under consideration (in this case 15) finally, estimating the consistency ratio via the mathematical expression cr = ci/ri according to saaty [10] where ci is the consistency index and ri the random index (as given by saaty [10]). table 5 below is a asian review of environmental and earth sciences, 2021, 8(1): 10-17 15 © 2021 by the authors; licensee asian online journal publishing group matrix whose comparison factors are the considered factors on one side and their respective derived weights on the other. with this matrix, the consistency vector was estimated. table-5. prioritization weight matrix. criteria code row total of the normalized matrix average weight (%) criteria name mwb 1.35 0.09 9.00 major waterbody etl 0.26 0.02 2.00 electricity transmission line lulc 2.70 0.18 18.0 landuse/landcover topo 0.54 0.04 4.00 topography (slope) spa 0.22 0.01 1.00 sensitive/protected areas cpa 0.22 0.01 1.00 critically polluted areas eia 2.79 0.19 19.0 existing industrial areas mtn 0.53 0.04 4.00 major transportation network pfz 0.21 0.01 1.00 proximity to flood zones srm 2.70 0.18 18.0 source of raw materials ws 0.62 0.04 4.00 wind speed lsm 0.22 0.01 1.00 large scale mines pd 1.14 0.08 8.00 population density pms 0.53 0.04 4.00 proximity to major settlements gwl 0.95 0.06 6.00 groundwater level total 15.00 1.00 100.00 table-6. the weights as factor matrix. code mwb etl lulc topo spa cpa eia mtn pfz srm ws lsm pd pms gwl weights 0.09 0.02 0.18 0.04 0.01 0.01 0.19 0.04 0.01 0.18 0.04 0.01 0.08 0.04 0.06 mwb 1.00 6.00 0.25 3.00 7.00 5.00 0.25 5.00 7.00 0.33 4.00 6.00 1.00 4.00 1.00 etl 0.02 1.00 0.11 0.33 1.00 2.00 0.11 0.50 2.00 0.11 0.33 1.00 0.17 0.50 0.17 lulc 4.00 9.00 1.00 6.00 9.00 8.00 1.00 7.00 9.00 1.00 6.00 8.00 3.00 7.00 3.00 topo 0.33 3.00 0.17 1.00 3.00 2.00 0.17 1.00 3.00 0.17 1.00 3.00 0.33 2.00 0.33 spa 0.14 1.00 0.11 0.33 1.00 1.00 0.11 0.25 1.00 0.11 0.25 1.00 0.17 0.50 0.17 cpa 0.20 0.50 0.13 0.50 1.00 1.00 0.11 0.33 1.00 0.11 0.33 1.00 0.20 0.33 0.20 eia 4.00 9.00 1.00 6.00 9.00 9.00 1.00 6.00 9.00 1.00 6.00 9.00 4.00 6.00 4.00 mtn 0.20 2.00 0.14 1.00 4.00 3.00 0.17 1.00 3.00 0.17 1.00 3.00 0.50 1.00 0.50 pfz 0.14 0.50 0.11 0.33 1.00 1.00 0.11 0.33 1.00 0.11 0.25 1.00 0.20 0.33 0.20 srm 3.00 9.00 1.00 6.00 9.00 9.00 1.00 6.00 9.00 1.00 5.00 9.00 4.00 6.00 4.00 ws 0.25 3.00 0.17 1.00 4.00 3.00 0.17 1.00 4.00 0.20 1.00 4.00 0.50 1.00 1.00 lsm 0.17 1.00 0.13 0.33 1.00 1.00 0.11 0.33 1.00 0.11 0.25 1.00 0.17 0.25 0.25 pd 1.00 6.00 0.33 3.00 6.00 5.00 0.25 2.00 5.00 0.25 2.00 6.00 1.00 2.00 2.00 pms 0.25 2.00 0.14 0.50 2.00 3.00 0.17 1.00 3.00 0.17 1.00 4.00 0.50 1.00 1.00 gwl 1.00 6.00 0.33 3.00 6.00 5.00 0.25 2.00 5.00 0.25 1.00 4.00 0.50 1.00 1.00 total 15.85 59.00 5.12 32.33 64.00 58.00 4.97 33.75 63.00 5.09 29.42 61.00 16.23 32.92 18.82 2.6.4. calculation of weighted column and weighted sum (consistency vector) the following steps were observed in calculating the consistency vector: a. a matrix showing the judgment comparisons and derived weights was started. b. using the priorities (weight) as factors for each column as shown in table 6 above, the values in each column of the comparison matrix were multiplied by their corresponding criterion weight in that column. e.g. 0.09 x 1 = 0.09, 0.09 x 0.02 = 0.018; 0.09 x 4 = 0.36 …………….. 0.09 x 1 = 0.09 c. adding up all the values in each row (weighted sum) e.g. for row 1: (0.09 + 0.11 + 0.05 + 0.11 + 0.10 + 0.08 + 0.05 + 0.18 + 0.10 + 0.06 + 0.17 + 0.09 + 0.08 + 0.14 + 0.06) = 1.44. table 7 shows the obtained weighted column and consistency sum matrix. table 8 shows the result of the consistency vector. this consistency vector is calculated thus: divide each of the weighted sums by their corresponding weighted value. table-7. obtained weighted column and consistency sum matrix. mwb etl lulc topo spa cpa eia mtn pfz srm ws lsm pd pms gwl weightedsum 0.09 0.11 0.05 0.11 0.10 0.08 0.05 0.18 0.10 0.06 0.17 0.09 0.08 0.14 0.06 1.44 0.01 0.02 0.02 0.01 0.01 0.03 0.02 0.02 0.03 0.02 0.01 0.01 0.01 0.02 0.01 0.27 0.36 0.16 0.18 0.22 0.13 0.12 0.19 0.25 0.13 0.18 0.25 0.12 0.23 0.25 0.19 2.94 0.03 0.05 0.03 0.04 0.04 0.03 0.03 0.04 0.04 0.03 0.04 0.04 0.03 0.07 0.02 0.56 0.01 0.02 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.02 0.01 0.01 0.01 0.02 0.01 0.22 0.02 0.01 0.02 0.02 0.01 0.02 0.02 0.01 0.01 0.02 0.01 0.01 0.02 0.01 0.01 0.23 0.36 0.16 0.18 0.22 0.13 0.14 0.19 0.21 0.13 0.18 0.25 0.13 0.30 0.21 0.25 3.04 0.02 0.04 0.03 0.04 0.06 0.05 0.03 0.04 0.04 0.03 0.04 0.04 0.04 0.04 0.03 0.55 0.01 0.01 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.02 0.01 0.01 0.02 0.01 0.01 0.21 0.27 0.16 0.18 0.22 0.13 0.14 0.19 0.21 0.13 0.18 0.21 0.13 0.30 0.21 0.25 2.91 0.02 0.05 0.03 0.04 0.06 0.05 0.03 0.04 0.06 0.04 0.04 0.06 0.04 0.04 0.06 0.64 0.01 0.02 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.02 0.23 0.09 0.10 0.06 0.11 0.09 0.08 0.05 0.07 0.07 0.04 0.08 0.09 0.08 0.07 0.13 1.20 0.02 0.04 0.03 0.02 0.03 0.05 0.03 0.04 0.04 0.03 0.04 0.06 0.04 0.04 0.06 0.55 0.09 0.10 0.06 0.11 0.09 0.08 0.05 0.07 0.07 0.04 0.04 0.06 0.04 0.04 0.06 1.00 asian review of environmental and earth sciences, 2021, 8(1): 10-17 16 © 2021 by the authors; licensee asian online journal publishing group table-8. the consistency vector. weighted sum consistency vector 1.44 / 0.089 16.18 0.27 / 0.018 15.00 2.94 / 0.180 16.33 0.56 / 0.036 15.55 0.22 / 0.015 14.62 0.23 / 0.015 15.33 3.04 / 0.186 16.34 0.55 / 0.036 15.28 0.21 / 0.014 15.00 2.91 / 0.179 16.26 0.64 / 0.042 15.24 0.23 / 0.015 15.33 1.20 / 0.076 15.97 0.55 / 0.036 15.28 1.00 / 0.064 15.63 2.6.5. calculation of the consistency index where n = total number of considered factors which in this case is 15, and (λ max) the summation of the elements of the consistency vector, ci (consistency index) can be calculated by the formula; ci = {(λ-n) / (n-1)} [10] therefore, λ max = (16.18 + 15.00 + 16.33 + 15.55 + 14.67 + 15.33 + 16.34 + 15.28 + 15.00 + 16.26 + 15.24 + 15.33 + 15.79 + 15.28 + 15.63) / 15 = (233.205 / 15) = 15.547 ci = (λ-n) / (n-1) ci = (15.547 – 15) / (15 – 1) = 0.0366. in calculating the constituency value, which is a ratio of consistency index to the random index, the mathematical expression; cr = ci/ri according to saaty [10] was used. random index (ri) is the inconsistency index of a randomly generated pair-wise comparison matrix of order 1 to 15 obtained by approximating random indices. see table 9. table-9. random inconsistency indices (ci) n 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 16 ri 0 0.00 0.52 0.89 1.11 1.25 1.35 1.40 1.45 1.49 1.52 1.54 1.56 1.58 1.59 1.73 where n = order of matrix when the order of a comparison matrix is n > 15, the average values of the random index ci may be roughly calculated using podvezko [13] formula as displayed in equation 2: 𝐶𝑙 = 1.98 (𝑛−2) 𝑛 (2) where n = number of criteria under consideration. consequently, the consistency ratio, in this case is cr = ci / ri. cr in this case is; 0.0366 / 1.59 = 0.023 3. result and analysis table 5 shows the computed average criteria weight for consistent respondents which revealed the influence level of the individual criteria considered for this study. the result from the calculated environmental criteria weights show that proximity of petroleum refinery to existing industrial areas; source of crude oil and landuse/landcover to have the highest influence value, followed by proximity to water body; population density; groundwater level; major settlement; wind speed; transportation network, topography, while sensitive/protected areas, critically polluted areas, and flood zones with the least influence value. the result of this ahp – based weight assessment would play a key role in any decision-making process involving the siting of a petroleum refining plant. it is anticipated that the results of this assessment can be used generally by planners, investors, environmental managers, and oil and gas experts as a general guide in the prioritization of criteria weights based on the influence of one criterion over the other in the suitability siting of petroleum refining plant. the result of this ahp – based weight assessment will play a key role in any decision-making process involving the siting of a petroleum refining plant. it is anticipated that the results of this assessment can be used generally by planners, investors, environmental managers and oil and gas experts as a general guide in the prioritization of criteria weights based on the influence of one criterion over the other in the suitability siting of petroleum refining plant. the findings agreed with the several studies [11, 13]. as a check on the reliability of respondents’ judgments, the consistency ratio (cr) for the judgment values was calculated. this consistency ratio value was found to be 0.023, which is less than 0.1. according to saaty [10] if this ratio is found to be less than 10% (cr< 0.1) then the respondent judgment is consistent, if otherwise (i.e. cr> 0.1) then the judgment is not consistent. by the result of this study, it means that there is a reasonable level of consistency in the comparison of the criteria by the respondent of this very outcome and that the computed weights are within the acceptable limit. if the reverse was the case (cr > 0.1) it means that the weights obtained are inconsistent and the judgment values need to be checked for logical correctness. 75% (60) of the total number of respondents were consistent in their judgment and the remaining 25% (14) were inconsistent. these inconsistencies in judgment by the responders may be a lack of logical knowledge of the pairwise comparison. asian review of environmental and earth sciences, 2021, 8(1): 10-17 17 © 2021 by the authors; licensee asian online journal publishing group 4. conclusion investors are constantly faced with tough decisions on the location of facilities that will yield the highest returns on low environmental impact. to optimize the benefits and constraints of particular land uses in a certain area, a planner needs to have a good knowledge of the influence of one criterion over the other. the analytic hierarchy process (ahp) has been proved by literature and existing projects to produce reliable and consistent results since it provides an alternative for a check and the fact that it can deal with inconsistent judgments and provides a measure of the inconsistency of the judgment makes the methodology a better solution that can help deal with the complex problems of a suitable site a selection like the one of this research (modular petroleum refining plant siting), which involves the consideration of multi-criteria/alternatives simultaneously. it is anticipated that the results of this assessment can be used generally by planners, investors, environmental managers, and oil and gas experts as a general guide during criteria weighting and prioritization based on the influence of one criterion over the other in the suitability siting of petroleum refining plant. references [1] j. f. k. akinbami, "an analysis of the demand and supply of electricity and the greenhouse gases emissions of the nigerian electrical power industry," a ph.d. thesis, technology planning and development unit (tpdu), obafemi awolowo university, ile-ife, nigeria, 2003. [2] c. j. campbell, the essence of oil and gas depletion. brentwood, new york: multi-science publishing co, 2003. [3] r. heinberg, the party’s over: oil, war and the fate of industrialized societies. british columbia: new society publishing, 2003. [4] p. r. odell, why carbon fuels will dominate the 21st century’s global energy economy. essex, uk: multi-science publishing company ltd, 2004. [5] a. milbrandt and r. p. overend, "the future of liquid biofuels for apec economies," report prepared for apec energy working group2008. [6] u.s. energy information administration (eia), international energy outlook (ieo): highlights. washington dc: us department of energy, 2010. [7] u.s. energy information administration (eia), international energy statistcis. washington dc: us department of energy, 2014. [8] p. negi and k. jain, "spatial multi-criteria analysis for siting groundwater polluting industries," journal of environmental informatics, vol. 12, pp. 54-63, 2008. [9] a. mohamed, b. shattri, b. nordin, and s. rashid, "gis based multicriteria approaches to housing site suitability assessment. ts 72 – gis spplications – planning," presented at the shaping the change, xxiii fig congress, munich, germany, october 8-13, 2006. [10] t. l. saaty, the analytic hierarchy process. new york: mcgraw-hill, 1980. [11] t. yamane, statistics: an introductory analysis, 2nd ed. new york: harper and row, 1967. [12] permadi, "multi-criteria land suitability evaluation for selected fruit crops in hilly region of central vietnam," phd dissertation submitted to humboldt university of berlin, germany, 1992. [13] v. podvezko, "complex evaluation of complex quantities," business: theory and practice, vol. 9, pp. 160-168, 2008. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 35 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 35-40, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi:10.20448/journal.506.2020.71.35.40 © 2020 by the authors; licensee asian online journal publishing group effects of urban encroachment on rural agricultural land: a case study of ibienafe community of edo state, nigeria jimoh, b.a.1 mustapha. d.2 bejide, o.i.3 ojeifo, d.o.4 (corresponding author) 1,2,4department of urban & regional planning, auchi polytechnic, auchi, nigeria. 3department of quantity surveying & geoformatics, auchi polytechnic, auchi, nigeria. abstract urban expansion constitutes one of the key agents of land-use change with the impact felt at local, regional and global levels; such impact includes spatial growth on agricultural land. this study assesses the effects of urban encroachment on rural agricultural land in the ibie-nafe community area of edo state, nigeria. the methodology adopted for the study is empirical research in which primary and secondary data were used for the study. on the other hand, findings show that the spreading of urban areas on farmlands causes new farmland reclamation and accelerated deforestation in the surroundings. in addition, the displaced farmlands do not ensure food production because of both reclaiming farmlands on infertile lands and diversifying farming activities from grain production to market-oriented ones. the accelerated urbanization and farmland displacement are driven by profit-oriented development strategy and ineffective land use planning. against this background, there is a need for an adequate understanding of the interplay between trends of urbanization and undermining agricultural land use within rural areas. keywords: encroachment, agricultural land, rural, urban, land-use, farmland. citation | jimoh, b.a.; mustapha. d.; bejide, o.i.; ojeifo, d.o. (2020). effects of urban encroachment on rural agricultural land: a case study of ibie-nafe community of edo state, nigeria. asian review of environmental and earth sciences, 7(1): 35-40. history: received: 16 december 2019 revised: 21 january 2020 accepted: 25 january 2020 published: 6 april 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 36 2. materials and methods ................................................................................................................................................................... 36 3. results ................................................................................................................................................................................................ 38 4. discussion .......................................................................................................................................................................................... 40 5. conclusion ......................................................................................................................................................................................... 40 references .............................................................................................................................................................................................. 40 https://www.asianonlinejournals.com/index.php/arees/article/view/1473 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.35.40&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2020, 7(1): 35-40 36 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study assesses the effects of urban encroachment on rural agricultural land in the ibienafe community area of edo state, nigeria. 1. introduction the world is rapidly urbanizing, and it has witnessed a tremendous shift of its population from being predominantly rural to predominantly urban in the last two decades [1]. the world’s population is estimated to be 7.01 billion and by the year 2030, more than 60% of this population was being living in urban areas especially in developing countries, consuming close to three-quarters of the world’s natural resources, and generating three quarters of its pollution and wastes [2, 3]. this growth will require unprecedented investment in new infrastructure and create serious challenges for political and social institutions. urban encroachment on agricultural lands has become a global phenomenon plaguing all countries of the world, rich or poor [4]. this phenomenon formed a challenge to most countries of the world, especially developing ones, because of the increasing in population at high rates, consequent in depletion of resources, especially agricultural lands around cities. the country with limited natural resources, agriculture is the primary resource in achieving food security; cultivation of agricultural land is the source of living for many families, like other developing countries, dramatically urban expansion in the last decades of the twentieth century increased as a result of natural increase of the population [5]. when the population increases, it leads to increase in the demand of lands for housing and human services. thus, the agricultural lands started decreasing day by day, and the rapid cultural transition and population growth have transformed the traditional dependency between people and the environment in nigeria, as a result of urbanization, with the absence of proper planning [6]. presently, the fast urban growth in nigeria is affecting approximately 400,000 hectares of vegetative cover every year adesina [7]. heimlich and anderson [8] observed that urban growth encourages encroachment blueprint, which most of the time possess negative effects on the ecology of the region, particularly in vegetative, hydro-geomorphology and food insecurity [9]. food security according to adesina [7] exists when every human, whatever the time, possess both economic and physical access to adequate, secured and wholesome food to meet up the standard dietary requirements and choice of food they prefer for a vibrant and vigorous living’. the transformation of agricultural lands to other land uses is a threat to food security, for instance, in one of the chilean city, about 1,734 hectares of wetlands and 1,417 hectares of agricultural land were transformed into residential areas between the years 1975 to 2000 [10]. rapid expansion of urban centre in estako-west mostly in places like auchi, ibie nafe, aviele and environs pose great challenges such that evokes interests from ecologists, planners, civil engineers, sociologists, administrators and policy makers on how much expansion is taking place, the effects on agricultural land and possible solution. this study focuses on such effects on the encroachment of agricultural land and suggests some mitigation measures. 2. materials and methods 2.1. research design data collection, analyse and interpretation are components of any study. this will assist in achieving best and consistency in the trend of events and points to be investigated. for the purpose of this research work, various techniques and procedures were being used to source relevant data that would revitalize the issue of infrastructure provision in the study area. 2.1.1. survey methodology an in-depth study was being carried out in the study area to determine the rate of urban encroachment on agricultural land in the study area. this was achieved through direct interview and observation and by using structured questionnaire. 2.1.2. reconnaissance survey a technically-based investigation was carried out in the study area to determine the area of coverage and the existing land use, physical condition of the place and its management mechanism. this was being done via observation; interview and a detailed questionnaire which was being administered so as to get the necessary information that would be required concerning the study area. 2.2. population ibienafe is a village located in estako west local government area in edo state, nigeria, having a total land area of 554.222hectares [11]. the community consists of 12,311 persons as shown by the 2006 population census. having a growth rate of 2.7%, a projection to 2019 showed the present population to be 17,408 persons. the study area is shown in figure 1a-d, and the encroachment of agricultural land is showed in figure 2e-h. 2.3. sample size the population of the research covered the residents of the study area. a sampling size is a subset of the population of the study selected for observation and analysis. a sample is a portion or specimen of larger group selected in such a way that attribute exhibited by smaller group are accepted as a representative of the whole group. a total of 100 questionnaires was being administered, using a sample size of 0.6% of the total residents. the questionnaire was administered randomly across ibie-nafe community. the satellite imagery in figure 1d indicates the data comparing the urban development and encroachment of agricultural in the study area. asian review of environmental and earth sciences, 2020, 7(1): 35-40 37 © 2020 by the authors; licensee asian online journal publishing group figure-1. map of nigeria showing edo state (a), map of edo state showing estako-west (b), baseline map of ibie-nafe community (c); and satellite imagery showing the existing built up area of ibie-nafe community of edo-state (d). source: ministry of land & survey, benin city, 2017. figure-2. power line transmission on agricultural land at ibie-nafe community (e), portion of rural agricultural land at ibie-nafe community (f), building materials on site for construction on agricultural land at ibie-nafe (g), and building construction ongoing on agricultural land at ibie-nafe. source: ministry of land & survey, benin city, 2017. asian review of environmental and earth sciences, 2020, 7(1): 35-40 38 © 2020 by the authors; licensee asian online journal publishing group 2.4. data analysis the response rate for each item in the questionnaire and site observation schedule, and the overall percentage of return from the sample size was determined. the data obtained was being analyzed using statistical program for social sciences (spss). the analyzed data will finally be presented using descriptive methods for easy interpretation and enable comparisons and inference to be drawn. 3. results 3.1. demographic responses the output of the administered questionnaire showed that 96 out of 100 retrieved questionnaires were analyzable. the result is sequentially presented according to the order in which they were organized based on the questionnaire administered. in table 1 and figure 3a show the total number of male respondents totaling 62 which represents 64.6% of interviewed people, whereas a total number of 34 female respondents which indicates 35.4% was also interviewed. therefore, it is deduced that more men responded than women. table-1. sex of respondents. sex respondents percentage male 62 64.6 female 34 35.4 total 96 100 source: field survey, 2019. table-2. ages of respondents age range no of respondents percentage (%) 18-28 8 8.3 29-28 18 18.3 39-48 19 19.3 49-58 32 33.3 59-above 19 19.8 total 96 100.0 source: field survey, 2019. out of the total number of 8 respondents which represent 8.3% of the population are between 18-28years. while 18 respondents (18.8%) of the population are between 29-38years. 19 respondents (19.8%) of the population are between 39-48years. 32 respondents (33.3%) of the population, are between 49-58 and 19 respondents (19.8%) of the population are 59 years and above. table 3 shows the marital status of the respondents used for this study. 22 respondents, which represent 22.9% of the population, are single, 53 respondents (55.2%) of the population, are married, 9 (9.4%) of the population are divorce, and 12 respondents (12.5%) of the population are widowed figure 2b. table-3. marital status of respondents. status number of respondents percentage single 22 22.9 married 53 55.2 divorce 9 9.4 widowed 12 12.5 total 96 100% source: field survey, 2019. figure-3a. sex of the respondents. figure-3b. respondents martial status. source: output analysis, 2019. source: output analysis, 2019 . the result in table 4 shows the respondent’s position in the household used for this study. forty seven (47) respondents (49%) of the population are head, 23 respondents (23.9%) of the population are spouse, 12 respondents (12.5%) of the population are relative, 10 respondents (10.4%) of the population represents child and 4 respondents (4.2%) of the population are categories under others specify. conversely, 9 respondents (9.4%) of the population are civil servants, 11 represent (11.5%) of the population are self-employed, 14 respondents (14.6%) of the population are unemployed, 19 respondents (19.7%) of the population are traders, 7 respondents (7.3%) of the population are retired, 24 respondents (25%) of the population are farmers, 5 respondents (5.2%) of the population are artisan and 7 respondents (7.3%) of the population are students. asian review of environmental and earth sciences, 2020, 7(1): 35-40 39 © 2020 by the authors; licensee asian online journal publishing group table-4. respondents position in the household. status number of respondents percentage head 47 49 spouse 23 23.9 relative 12 12.5 child 10 10.4 others specify 4 4.2 total 96 100% source: field survey, 2019. table-5. occupation of respondents. status number of respondents percentage civil service 9 9.4 self employed 11 11.5 unemployed 14 14.6 trading 19 19.7 retired 7 7.3 farming 24 25 artisan 5 5.2 student 7 7.3 total 96 100% source: field survey, 2019. figure-4a. respondents position in the household. source: output analysis, 2019. figure-4b. occupation of respondents. source: output analysis, 2019. 3.2. causes of encroachment of agricultural land the causes of agricultural land encroachment in the study were identified. the result in table 6 showed that 57 respondents (59.4%) indicated that migration is the major source of encroachment, while 21 (21.8%) and 18 (18.8%) of the respondents showed that natural birthrate and urbanization could cause agricultural land encroachment. the result in table 7 shows that current agricultural land use dynamics has the highest residential use as indicated by the respondent. a total number of 8 respondents (8.3%) represent the land use for farming only, while 42 respondents (44%) represent residential land use. also, residential and mixed land use represent 29% of 28 respondents, while 18 respondents (18.7%) indicated other land use activities. table-6. causes of encroachment on agricultural land. causes of encroachment on agricultural land number of respondents percentage (%) migration 57 59.4 natural birth rate 21 21.8 urbanization 18 18.8 total 96 100 source: field survey, 2019. table-7. current agricultural land use dynamics. current agricultural land use dynamics number of respondents percentage farming only 8 8.3 residential only 42 44 residential and mixed use 28 29 others specify 18 18.7 total 96 100% source: field survey, 2019. 3.3. effects of encroachment on food security and land acquisition the result in table 8 shows the responses to the effects of encroachment on food security and land acquisition. a total number of 57 respondents which represent 59.3% of the population agreed that encroachment could cause food insecurity, whereas 18 (18.8%) of the population were of different opinion. finally, 21 respondents (21.9%) were indifferent on the possible negative effects of encroachment on food security. however, the results in table 9 show the responses of the dwellers to the effect of encroachment on land acquisition. a total number of 63 asian review of environmental and earth sciences, 2020, 7(1): 35-40 40 © 2020 by the authors; licensee asian online journal publishing group respondents from the 96 of the population indicated that encroachment has effect on land acquisition, whereas 12 respondents (12.5%) of the population disagree on land acquisition and encroachment, and 21 (21.9%) of the population were indifferent. source: field study, 2019. table-9. effects of encroachment on land acquisition. effect of encroachment on land acquisition no of respondents percentage (%) yes 63 65.6 no 12 12.5 may be 21 21.9 total 96 100.0 source: field study, 2019. 4. discussion ibie-nafe community of etsako west area, of edo state, is experiencing many socio-economic and political changes that are impacting negatively on the ecological landscape. in the area of agricultural sector as assessed in this study, the following observations are noteworthy. the rate of urbanization is taking its toll on ibienafe community of etsako west area, of edo state faster than envisaged by the planning authority and even the administrators. the urbanization growth rate of the area is increasing significantly from 2% annually between 1991 to 2.7% annually between 2018 and 2019. developmental activities are encroaching into the agricultural lands at an alarming rate annually. if of this growth rate continues, it implies that by the year 2030, agricultural land (arable land, farmable land and forest) would have further been lost to urban encroachment. erections of power line were also identified as a major agent of change in the area due to the large industrialization activities within the area, which has led to loss rural agricultural in ibie-nafe community. 5. conclusion it is evident from the above analysis that the population growth has changed the land use pattern of the city. agricultural land is being gradually converted into built-up land like industrial, residential, commercial and other urban uses without any systematic development plan. similarly, the household area has been converted into agricultural and built up area. these problems require immediate attention of the planners and administrators. the encroachment of the community leaves marked impact on the land use pattern, which has shown tilt towards builtup areas, which is growing in an unplanned way along the main roads. the rate, at which agricultural land is being destroyed, needs serious thinking on part of planners and policy makers. the population growth of the community and encroachment has changed internal morphology of the community. references [1] a. de-sherbinin, population – development – environment dynamics in the developing world” in de sherbinin, a., a. rahman, a. barbieri, j.c. fotso, and y. zhu (eds.). 2009. urban population-environment dynamics in the developing world: case studies and lessons learned. paris: committee for international cooperation in national research in demography (cicred), 2007. [2] w. peters, "green cities-urban environmental solutions," global issues-an electronic journal of the us department of state, march, vol. 5, pp. 1-39, 2000. [3] c. l. redman and n. s. jones, "the environmental, social, and health dimensions of urban expansion," population and environment, vol. 26, pp. 505-520, 2005. available at: https://doi.org/10.1007/s11111-005-0010-1. [4] x. lu and s. huang, "barriers and solutions to china’s cultivated land protection," international journal of environmental studies, vol. 67, pp. 223-232, 2010. available at: https://doi.org/10.1080/00207231003696343. [5] g. ralph, the american farmland trust vol. 46. california: duxbury press, 2008. [6] d. h. bari, "impact of rabid urban growth on sustainability of soil and water resources in jordan," ciheam mediterranean options: series a. mediterranean seminars, vol. 44, pp. 223231, 2001. [7] f. a. adesina, "geoinformation and natural resources exploitation in africa; united nations economic and social council," presented at the paper delivered in: fourth meeting of the committee on development information, addis ababa on 23-28 april, 2005. [8] r. e. heimlich and w. d. anderson, "development at the urban fringe and beyond: impacts on agriculture and rural land." vol. 803, ed washington d.c: economic research service, u.s. department of agriculture, 2001, p. 80. [9] f. lambin, h. geist, and e. lepers, "dynamics of land use and land cover tropical regions," global issues-an electronic journal of the us department of state, vol. 6, pp. 10-15, 2003. [10] n. g. kwasi, "urbanization process–environmental and health effect in africa," population environment research network (pern) cybersermina, urban expansion: the environmental and health dimensio, 2004. [11] report, "categorization of agro-ecological zones in edo state," bulletin, vol. 6, p. 71, 2000. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. table-8. effects of encroachment on food security. effect of encroachment on food security no of respondents percentage (%) yes 57 59.3 no 18 18.8 may be 21 21.9 total 96 100.0 47 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 47-69, 2019 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.47.69 © 2019 by the authors; licensee asian online journal publishing group surface and ground water pollution in bangladesh: a review akash mamon sarkar1 a. k. m. lutfor rahman2 abdus samad3 arjun chandra bhowmick4 jahida binte islam5 ( corresponding author) 1pulp and paper research division, bangladesh council of scientific and industrial research, bangladesh. 2,3department of chemistry, jagannath university, bangladesh. 4department of chemistry, university of south dakota, vermillion, united states. 5department of chemistry for materials, mie university, japan. abstract environmental analysis does not become properly meaningful unless follow the standard procedure in sampling, preserving and also in analysis. this study investigates different studies on surface and groundwater pollution and discusses their findings along with impacts on environment, human health and aquatic ecosystem demolition. fresh water is a vital need for drinking, household, agricultural and industrial use. fresh water availability is shrinking worldwide due to imprudent use. abound availability of fresh water in bangladesh is now polluting due to unwise dumping of industrial, household, agricultural and municipal wastes. water body in urban arena is severely polluted rather than rural part. the over concentration of do, bod, cod, ec, tds, cr, cd, pb was observed in dhaka region. the highest arsenic concentration was found in the ground water of lakshimpur. the main sources of pollution in industrial cities are anthropogenic sources like untreated industrial effluent and municipal wastes whereas in rural part the main sources of pollution are agricultural and naturogenic. transboundary impact also intensifies some river water pollution. government approved the policies, ordinance, acts and laws however, due to lack of proper implementation and monitoring water pollution problem increasing day by day. keywords: effluent, heavy metal, pesticides, ecosystem, pharmaceuticals, environmental policy. citation | akash mamon sarkar; a. k. m. lutfor rahman; abdus samad; arjun chandra bhowmick; jahida binte islam (2019). surface and ground water pollution in bangladesh: a review. asian review of environmental and earth sciences, 6(1): 47-69. history: received: 13 august 2019 revised: 17 september 2019 accepted: 23 october 2019 published: 9 december 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: author wants to acknowledge library of bcsir and the library of the university of south dakota for information access. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 48 2. water pollution ............................................................................................................................................................................... 50 3. handicap in sampling and analysis ............................................................................................................................................. 63 4. environmental policies in bangladesh ........................................................................................................................................ 63 5. conclusion ......................................................................................................................................................................................... 64 references .............................................................................................................................................................................................. 64 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.47.69&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 https://www.asianonlinejournals.com/index.php/arees/article/view/1147 https://orcid.org/0000-0002-0277-6916 https://orcid.org/0000-0001-7258-3506 https://orcid.org/0000-0001-5601-3124 https://orcid.org/0000-0003-1557-4499 https://orcid.org/0000-0001-6718-8982 asian review of environmental and earth sciences, 2019, 6(1): 47-69 48 © 2019 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes to the existing literature by investigating different studies on surface and groundwater pollution and discusses their findings along with impacts on environment, human health and aquatic ecosystem demolition. 1. introduction bangladesh after forty four yours of achieving independence entered into the list of lower middle income country in 2016 according to the world bank. industrial development policy was upheld by the government in first five year plane after liberation in 1973 [1]. this industrial development policy has been carried out by all the following government unless some alterations even till now. therefore, agriculture based economy of bangladesh is gradually shifting into the industry based economy. that industrial journey was significantly started through the establishment of garments and textile industries in the last two decades of previous century. contribution of agriculture to the gdp in 1981 was 30 % [2] whereas in 2016 that was 14.8 % [3, 4]. agricultural constant price gdp growth rate in 2016 was 11.1 % and by industries was 32.4 % [3]. however, the contribution of manufacturing sector to the gdp in 1981 was 13 % [2] where as in 2016 that was 29.3 % [3, 4]. bangladesh is now a middle income country and the government already has divulged their target to enter in the list of developed country by 2041. to reach that goal, government emphasized the industrial development by local and foreign investment. eight export processing zones (epz) have already been established in response of foreign investment and technology transfer for creating employment opportunities. recently, an economic zone is going to establish in cox’sbazar area. to support the industrial development, port and power facilities is trying to improve on priority basis. therefore, construction of the paira sea port is running fast with special care. the coal based power plants in rampal and atomic energy based power plants in ruppur are under consideration. in accordance with industrial development policy, the government has not divulged the environmental protection policies. already, the surface water quality of different rivers around dhaka and chittagong region has been demolished. a strong protest has already been raised among the national and international environmental scientist, environmental protection organization and concerning people about the establishment of rampal coal based power plants in sundorban arena. this concern has been raised because of the different environmental issues like hot water will increase the temperature of surrounding river, particulate matter emitted from the kiln will may affect the local and far away environment [5, 6] the ph may be declined by sinking of coal carrying cargos etc. all of these concerning incidents might be the reasons for destroying the ecosystem of world heritage surdarban forest. environment is one of the prime concerns all over the world for sustainable development nevertheless the government has taken of consideration about environment in development program. asian review of environmental and earth sciences, 2019, 6(1): 47-69 49 © 2019 by the authors; licensee asian online journal publishing group figure-1. main rivers in bangladesh. source: banglapedia, 2005. bangladesh is a large delta and 230 rivers have been flown over this country figure 1. most of the industries have been established on the bank of the river and are dumping their wastes into the nearby river without proper pretreatment subsequently damaging the aquatic environment [7]. as a consequence the river water quality in industrial region is deteriorating day by day. the rivers in the urban area are mainly polluted by industrial effluent, municipal wastes, hospital wastes and the sources of river pollution in the rural area are mainly land run off (fertilizer, pesticides), human wastes and naturogenic. the portion of buriganga river near the southern edge of dhaka city is almost biologically dead [8] as well as the turag, shitallakhya and balu river water quality is unfavorable for aquatic life [9-11]. the color of the buriganga, turag, shitalakkhya, balu and some other river water during dry season becomes dark [8, 10, 12, 13] which is not suitable for sunlight penetration. therefore, the photosynthesis becomes hindered in the water body which affects the hydrochemistry and ecosystem. the surface water of the rivers in the rural district far from the industrial region is till suitable for aquatic biota [14, 15] whereas in the urban or industrial districts are polluted by organic as well as inorganic sources and are exposing adverse effects for aquatic ecosystem [16-18]. all over the world, water borne diseases are prime concern among people. a wide range of mortality and morbidity occurs by dint of water related diseases especially in developing countries through ingesting pathogenic bacteria, viruses, penetration through human skin by infective forms [19]. the common sources of pollution and its effects are summarized in figure 2. figure-2. water pollution and its effects. source: prensa latina; fakesick; iwa, india celebrating. asian review of environmental and earth sciences, 2019, 6(1): 47-69 50 © 2019 by the authors; licensee asian online journal publishing group this review has an aim to discuss some handicap in polluted water analysis, the sources of water pollution, adverse effects of pollution on hydrochemistry and ecosystem and environmental policies in bangladesh. the concentration of major pollutants aggregation in surface and groundwater and their health risks have been discussed. some statistical analysis and the inter-correlation of pollution causing parameters have also been embodied in this review. 2. water pollution in recent past decades, bangladesh had been faced the dangerous arsenic pollution problem which is attributed to tremendous public health problem. beside this, the ecological condition mortification of some rivers in the industrial zone has been drawn the concern. severe water pollution may be caused by organic (indicated by cod, bod, do, grease, oil, volatile organic carbon etc.), inorganic (indicated by temperature, acid, base, tss, salinity, metals etc.), ions (e.g. anion, cation) and pathogenic (e.g. bacteria, virous, protozoa etc.) sources from industrial, municipal, hospital wastes as well as naturogenic sources. 2.1. organic pollution organic pollution of water occur by the bio-degradable wastes from industrial and domestic sources which stimulates the growth of micro-organism in the water body [8]. as a consequence of microbial decomposition, the oxygen in the water body is consumed and the quality balance is disturbed. water pollution mostly occurred in developing countries as a result of miss management of industrial, municipal, hospital wastes and dumping into the water body [20-22]. dissolve oxygen (do) and chemical oxygen demand (cod) are commonly used for the determination of organic pollution level of water body [8, 10]. according to the who, the permissible limit of do and cod in industrial wastewater and drinking water is 4.5-6.5 mg/l and 10 mg/l, respectively [23]. pollution of surface and groundwater in different regions of bangladesh from organic sources has been summarized in table 1. the main rivers around dhaka city have been polluting drastically due to the untreated industrial and municipal wastes from the last couple of decades. buriganga is one of the main rivers in dhaka city which has lower level of do (0.9-2.8 mg/l) [24] and higher level of cod (140-800 mg/l) value [8]. similar condition has been observed in case of turag rive which flows beside the dhaka city [9, 25]. the water quality of shitalakkha river is also unfavorable for aquatic biota due to organic pollution [10, 26, 27]. as a consequence of high level of organic pollution aquatic ecosystem in the surrounding rivers of dhaka city is almost ruined [8, 12, 28]. beside the peripheral river of dhaka city, dhanmondi lake, gulsan lake, rampura lake, ramna lake are polluted by volatile organic carbon (voc) [29]. burignaga river is also polluted by voc [30]. however, the rivers far from the industrial region are not such highly polluted. the do, cod and bod levels of jamuna, meghna, podma, mahuri, surma, ganges river are in the permissible level [31-34]. the permissible level of do, cod and bod indicates that the lower dumping of organic wastes and lower aerobic bacterial decomposition has been occurred in those rivers. a very recent study showed that cod level (20.84-114.6) in the meghna river is higher than permissible level [15]. this is may be occurred due to the transboundary water flow from polluted buriganga and shitalakkhya river into the meghna river. do is a conventional parameter for assessing the water quality which indicates the availability of life in water body [10]. do provides essential direct and indirect information about water body such as, bacterial activity, photosynthesis, availability of nutrients, stratification and so on premlata [19]. at the lower level of do value, fish and other aquatic organisms may not survive [40]. the rivers buriganga, turag, shitalakkhya, dhaleshwari, bongshi, surma table 1 are polluted by organic pollutant as those have lower do value according to doe [41] and who (world health organization) [42]. cod is another essential parameter for assessing the soundness of water body. higher value of cod indicates more organic pollution. cod value is enhanced by the urban runoff with household wastes and wastes from streets and sidewalks, fertilizers, leaves, grass clippings and paper from residential areas [43]. the enhanced level of cod value makes the water dark in color which hindered the penetration of sunlight. as a consequence, the photosynthesis of aquatic weeds affected drastically. therefore, the hydrochemistry and aquatic ecosystem disturbed badly. beside this, higher level of cod value makes the water nuisance in smell. fish, aquatic biota feels suffocating with higher level of cod in a water body. cod enriched water is another source of pathogenic bacteria and virus. the use of cod enriched water is not suitable for drinking, washing and other household uses. the use of this water may highly risk for sore on skin. the river buriganga [8] turag [9, 25] shitallakhya [10, 26] and meghna [15] are highly polluted which is indicated by higher level of cod value. bod represents the amount of oxygen required by the living organisms in water body which are associated with utilization and ultimate destruction or stabilization of organic matter [44]. bod is an indicator of water pollution. it may represents, how much oxygen is necessary for oxidizing a given quantity of organic matter by microbes [45]. bod value is lower in clean water which reveals more oxygen is present in water body and ultimate more nutrients is available for high forms of life in water body. the reason of higher bod value is same as lower do value. at higher bod value the aquatic biota are stressed, suffocated and in some cases died. the consequence of higher value of bod is leaves and woody derbis, dead plants and animals, animal manure, effluents from different industries and urban storm water runoff [46]. most of the rivers in industrial arena show bod value above the permissible level however, the rivers in rural zone that show in the permissible level table 1. vocs are concerning environmental pollutant as a consequence of their toxicity exerted to the environment and widespread occurrence. voc comes from solvent and important raw materials used in different industries, oil from water vehicles and oil spilling from tanker, ship scraps, paints, adhesives, deodorants and refrigerants [47]. some vocs are used in agricultural practices and as fumigants, as herbicides and as solvent for pesticides [48]. oceans, marine algae, phytoplankton and forest soil consist remarkable sources of biogenic vocs [49] water sample from 5 to 25 m depth is used for voc detection. asian review of environmental and earth sciences, 2019, 6(1): 47-69 51 © 2019 by the authors; licensee asian online journal publishing group table-1. organic contamination of various surface and groundwater samples in bangladesh. sampling location no. of observation polluting parameters references total polluted do mg/l cod mg/l bod mg/l voc (µg/ml) benzene toluene xylene surface water buriganga river 10 0.35-0.37 0.16-0.23 0.12-0.14 [30]c buriganga river 5 5 1.8-6.5 17.3-41.9 [20]b buriganga river 4 4 1.1-4.1 140-800 [8]a buriganga river 0.9-2.8 17.2-60.1 2.5-34.5 [24] gulsan lake 33.09-52.12 2.11-2.29 [29] turag river 3 3 2.1-6.8 21-220 10-180 [25] turag river 4 4 0.6-3.6 220-1550 [9] bangshi river 1 1 3.2-6.3 0.02-2.1 15.23-96.12 [35]d dmd embankment 12 12 0.0-2.57 400-2004 150-977 [27] dhaleshwari river 5 0 6.37-6.63 -(4.1-1.46) [36]b surma river 5 0 3.5-7.6 0.9-2.6 0.6-1.8 [31]b surma river 167 1.40-7.60 0.16-2.60 0.10 -1.80 [37]b meghna river 6.23 8.54 6.38 [32] meghna river 11 4.66-8.35 20.84-114.6 1.2-10.1 [15] ganges river 1 10.7-6.4 10.3-15.75 4.55-1.1 [33]e brahmaputra river 1 9.85-6.7 75-16 4.6-0.66 [33]e padma river 6.21-9.61 3.9-5.1 [34]d dhanmondi lake 16.98-23.78 2.68-2.92 [29] rupnagar lake 19.33-24.02 2.08-2.15 [29] ramna lake 13.78-16.87 2.74-2.99 [29] shitalakkhya river 3 3 1.2-3.12 89.72-118.1 25.12-35.12 [26]e shitalakkhya river 5 5 0.5-3.3 80-480 [10] jamuna river 6.8 3.2 [38] padma river 6.1 1.9 [38] dakatia river 5.06 3.09 2.41 [32] muhuri river 4.88 2.87 2.61 [32] vahirab irver 1.22-5.51 3.80-10.80 0.22-5.79 [39] groundwater feni 1.25-3.34 [32] aobserved every two month over the year; bobserved in wet and dry seasons; cobserved in 0 cm and 15 cm depth, in c18 column; dobserved at every month over the year, eobserved in monsoon, premonson and postmonson. asian review of environmental and earth sciences, 2019, 6(1): 47-69 52 © 2019 by the authors; licensee asian online journal publishing group fondekar and gupta found higher values of hydrocarbon in the 10 m depth of an oil tanker route in northern indian ocean [50]. it was observed that mentionable amount of benzene, toluene and xylene has been found in the burigana river, gulsan lake, dhanmondi lake, raman lake and rampura lake table 1. among them gulsan lake is more polluted by toluene by amounting 33.09-52.12 µg/ml [29]. the sources of this high concentration of toluene are may be the industrial and municipal wastes and insecticides used by the municipality. at a very low concentration of vocs exerts severe health risk as many of these materials are toxic, carcinogenic or mutagenic [51]. oil pollution depletes the water quality by dropping down the level of do and increasing the cod, bod, tss and th value of water body [52]. according to apa, ≥ 10 ppm concentration of oil in water body can cause lethal for aquatic habitant [53]. in december 2014, chowdhury and akter found 295-1650 ppm and 6.68-11.3 ppm oil at the contaminated and uncontaminated region of shela river, respectively due oil tanker slammed in eastern part of sundarbans mangrove forests [54]. islam and hossain also found high concentration of oil (9280-10800 ppm) at ship scrapping area in chittagong [55]. another oil tanker slammed in the karnafui river on october 24, 2019. beside these, the oil pollution in buriganga river is a common scenario from ship terminal and shipyard due to pore management. the natural decomposition of oil is highly slow and may endure for decades [56]. oil spill affects the fisheries breeding place. the high concentration of oil restricts the sunlight penetration underneath of oil layer in water body. lack of light intensity suppresses the photosynthesis of phytoplankton which impairs the oxygen and carbon dioxide balance across the air-water interface [55] substantially depletes the water ecosystem. it also inhibits the swimming and flying capacity of wetland birds due to over-weight [57]. 2.2. inorganic pollution inorganic pollutants (especially acids, salts and metals) are not biodegradable. they form homogeneous or heterogeneous mixture and persist in the water body. over the permissible limit, they exert toxicity and adverse effect for aquatic ecosystem, diversity of aquatic life and human health. inorganic pollutants are in active pollutants group. the sources of inorganic pollution are the industrial untreated wastes, municipal wastes, hospital wastes, road wash, agricultural wastes and in some cases naturogenic. bangladesh is an emerging industrial country with its unplanned industries. most of the industries dump their wastes without proper treatment into the nearest water body. textile manufacturing and garments industries are the main contributing industries in bangladesh and prime surface water pollution causing industries with their untreated effluent [58, 59]. inorganic pollutions have been treated major pollution causing components in bangladesh from last couple of decades because of the deficiency of wastes treatment facilities. many studies mentioned highly inorganic pollution in surface and groundwater in the different parts of country is summarized in table 2 which is directed by the higher level of ec and hardness. surface water is seriously polluted by discharging of agricultural effluent [8, 20] industrial effluents, random throwing of household, clinical, pathological and commercial wastes, fuel and sewage wastes [60]. groundwater pollution may be due to the naturogenic sources [61] and the leaching of industrial waste water. ph is an important water quality assessing parameter which determines the corrosive characteristic of water [10]. intuitively, ph significantly affects the biological activities and efficiency of toxic substances present in the aquatic environment [9]. photosynthesis of water body is greatly affected by the ph level of water. if photosynthesis rate is decreased then carbon dioxide and bicarbonates inclusion are increased subsequently ph of the water body is increased [72]. the ph level is affected by the reaction of carbon dioxide, organic and inorganic solutes present in water [34]. the buffer (ph level) protection of water body is one of the major parameters. the ph maintained by a well-buffered is attributed by the fact of normally running water and is influenced by the nature of the deposits over which the water flows [73]. a slight change from the certain ph level of water for an organism can be abolishing cause for that organism [74]. in summer, water show alkaline nature may be due to the increase of photosynthesis of the algal blooms resulting into the precipitation of carbonates of calcium and magnesium from bicarbonates, whereas in winter ph level decreased due to the decrease of photosynthesis [34]. ph value of the surface and groundwater samples recommended by who is 6.5-8.5 [23]. according to eqs the ph levels in industrial water, fishing water and drinking water are 6.0-9.5, 6.5-8.5 and 6.5-8.5, respectively [75]. in all the studies the ph level was in the permissible limit recommended by eqs except karnaphuli river which shows higher level of (ph = 9.86) alkalinity [61]. the higher value of ph in the karnaphuli river may be due to the untreated karnaphuli paper mill effluent discharged into the river. beside this some other industries situated on the bank of the karnaphuli river are discharging their effluent without any treatment. ph value in surface water is slightly higher than the groundwater could be due to the increased photosynthetic assimilation of dissolved inorganic carbon by plankton [70]. electrical conductivity (ec) demonstrates the total ionic species in the water. higher value of ec depicts that larger quantity of mineral salts are present in the water [76]. high content of mineral salt affects the irrigation scheme. ec is strongly related with total solid [60]. according to the who the maximum permissible limit of ec is 1500 µs/cm [77]. ec found well below than the who recommended limit in surface water however, the ec concentration in groundwater of feni, noakhali, lakshmipur, khulna and comilla region was found in dangerous limit table 2. higher level of ec in these regions is may be attributed to the proximity of bay of bengal where saline water flow comes with tidal force. higher level of conductivity as well as dissolved solids may have certain physiological effects on desirable food plants as well as habitat-forming plant species, give mineral testes in drinking water and create problem in irrigation [78]. asian review of environmental and earth sciences, 2019, 6(1): 47-69 53 © 2019 by the authors; licensee asian online journal publishing group table-2. inorganic contamination of various surface and groundwater samples in bangladesh. sampling location no. of observation ph ec µs/cm tds mg/l tss mg/l salinity mg/l alkalinity mg/l hardness mg/l references total polluted surface water panguchi river 7.23-8.09 201.96-465.87 228-284 42.66-71.16 56.68-74.79 [60]a buriganga river 6.92-7.82 622.2-1093.47 544-789 67.43-159.42 91.94-163.1 [60]a buriganga river 6.7-7.7 146-1309 98-871 71-642 [8] turag river 8.23-9.45 985-1362 684-898 436-612 [12] padma river 6.8-8.66 43-112 20.4-237.4 80-240 60-120 [34]b surma river 4 51.5-301.6 30.67-115.67 61.67-175.17 [62] bongshi river 545-605 384-429 261-305 [43] karnatoli river 2 2 90.7-1148.0 78.35-1282.4 0.0-1.03 [63]a dhaleshwari river 5 0 5.0-7.65 136-540 69-299 126-640 16-68 [40]a mouri river 6 7.3-8.3 164-275 255-305 74.5-123.3 354-570 34.45-280 [64] muhuri river 65.90 32.70 66.82 40 [32] shitalakhya river 6.6-8.0 135-4768 49-355 [65] shitalakhya river 6.9-8.0 121-1167 80-754 57-582 [10] dakatia river 6.78 179.15 89.85 80.00 56.02 107.00 [61] dakatia river 112.40 56.25 52.71 58.0 [32] meghna river 7.04 414.95 207.40 70.0 50.75 90.0 [61] meghna river 1193.5 598.5 50.75 340.0 [32] rajakhali canal 6.5-8.8 334-951 0.0002-0.001 78-270 36.3-88.9 [66] sunamganj 117.51-503.61 215-48250 [67] halda river 7.03-8.60 72.00-414.00 30.0-200.0 20.0-653.0 2.12-35.36 9.0-380.0 [68] karnafuli river 6.36-9.86 90.0-45600.0 45.0-20000.0 14.4-5100.0 1.60-52.25 10.0-4500.0 [68] groundwater feni 6.08-8.86 172.2-2528.0 85.3-262.0 75.48-258.0 26-554 [32] noakhali 6.57-7.91 483.0-9520.0 241.0-4800.0 148.24-760.32 148-1530 [32] lakshmipur 6.83-7.52 52.2-3800.0 129.3-1920.0 108.6-1017.72 134-630 [32] northwest region 5.4-5.6 160-460 95-287 100-300 [69] mohanpur 6.9-7.1 701-987 490.7-990.9 373.8-495.8 301.6-400.0 [70] khulna 26 25 962-9370 480-4640 [71] comilla 5.8-7.58 73.20-1797.0 36.50-749.0 21.33-1046.69 26.0-684.0 [61] aobservation was made three times over the year; bobservation was made by monthly. asian review of environmental and earth sciences, 2019, 6(1): 47-69 54 © 2019 by the authors; licensee asian online journal publishing group total dissolved solid (tds) in water mainly consists of ammonia, nitrite, nitrate, phosphate, alkalis, some acids, sulphates, metallic ions and so on [27]. tds is not generally treated as a primary contaminant (as it is not directly associated with health effect) but used as an indicator of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants [34]. excess amount of tds makes the water more turbid and increase its electrical conductivity [79, 80]. higher quantity of tds in effluents can increase the density of water, influence osmoregulation of fresh water organisms, reduce solubility of gases (like oxygen) and impair the utility of water for drinking, irrigation and industrial purpose [27]. tds indicates the saline behavior of water. the high concentration of tds means higher concentration of salinity in the water. salinity could also be a major limiting factor for crop yield in poorly drained soils [81]. according to the who guide line the maximum permissible value of tds in drinking water is 500 mg/l and in irrigable water is 1500 mg/l [77]. both surface and groundwater in and around industrial area shows higher level of tds vales for drinking water than the who’s guideline value table 2. however, the rivers in the rural area show tds value well fit into the permissible level. total suspended solids (tss) depict the suspended impurities present in the water which are responsible to transport pollutant in the aquatic environment [27]. suspended solids may be appear in the form of course, floating, fine or colloidal particles as a floating film which cause ecological imbalance in the aquatic ecosystem by mechanical abrasive action [34]. untreated or partially treated industrial, municipal, hospital and agricultural wastes intensify the tss value in water body [12]. tss is highly ph susceptible. therefore, with ph change the dissolved matter can be aggregated and precipitated [82]. the permissible limit of tss in drinking water is 5 mg/l [83] and in industrial waste water is 150 mg/l [84]. the karnafuli, halda and bongshi rivers contain the exceed limit of tss value for industrial effluent table 2. these rivers are situated in the industrial belt of the country. most of the industries have no well-organized effluent treatment plant and they are dumping their effluent into the nearest river. therefore, higher value of tss has been experienced in the river of industrial region. salinity means the saltiness or dissolved salt content in the water such as sodium chloride, magnesium and calcium sulfates and bicarbonates [34]. the elevated saline content in water affects the soil construction, permeability and aeration which affect the growth of seedlings [85]. ecologically salinity is an important factor for influencing the types of organisms that live in the water body [34]. various species of fresh water fish cannot get suitable environment for reproduction in high content of saline water [8]. highly concentrated saline water declines the fish diversity at an alarming rate which effects on biodiversity subsequently correlates with ecosystem as well as human food chain [8, 86]. the ultimate effect of high saline content in drinking water is detrimental on blood pressure, kidney as well as menstrual process of women [8]. dietary salt intake guideline has been established by who, but guideline for safe salinity has never been published except the sodium contents > 200 mg/l in drinking water [87]. higher rate of preeclampsia and gestational hypertension in pregnant women living in the southwestern coastal region of bangladesh has been noticed compared with noncoastal pregnant women which may be caused by saline contamination in drinking water [88]. in surface water highest level of salinity was recorded in buriganga river (642 mg/l) and turag river (612 mg/l) [8, 12]. the dominant sources of salinity are tidal force, irrigation and industrial effluents. alkalinity is the capability of water to neutralize a strong acid into a designated ph [60]. in natural water most of the alkalinity is attributed to the dissolution of co2 into water [70] and in industrial region most of the surface water turned alkaline due to the untreated effluent. surface water of the buriganga, dhalashari, mouri rivers and ground water of southeast region (feni, noakhali, laxmipur, comilla) consists higher level of alkalinity table 2. according to the who, acceptable limit of total hardness is 200 mg/l for drinking water which can be extended up to 600 mg/l in case of non-availability of fresh water source [77]. hard water does not exert any known health impact but it forms foams which creates heat insulating scales in the boilers and reducing the efficiency [80]. karnafuli river showed the highest range of hardness like 10-4500.0 mg/l [68] which is attributed to the industrial effluent. groundwater in comilla and noakhali regions experienced hardness over the who guided limit for drinking water [32, 68]. this higher value may be due to the naturogenic as the industrial source in those regions is limited. hard water exerts unpleasant test in drinking water. 2.2.1. trace metals water from natural sources contain impurities of trace metals as it dissolves these metals while flowing downward through hydrological cycle [102]. beside the natural pollution, some human activities like large scale use of chemicals in agricultural field, unauthorized disposal of industrial, hospital, mining and research wastes are attributed to pollute surface and groundwater. some trace metals are essential for human health whereas overloading these metals cause health problems in living organism especially human. trace metals are immobilizing in aquatic system as well as non-biodegradable and can accumulate onto sediment and in plant tissue [12, 103]. trace metals are accumulated as a consequence of coagulation, ion exchange with dissolved and suspended species in water, incorporation into the mineral lattice structure and precipitation due to the formation of insoluble species [104-106]. trace metals are remained in the form of oxides, hydroxides, sulphides, shlphates, phosphates, silicates, organic bindings forming complexes with humid compounds and complex sugars [107]. surface water is a vital source of irrigation in bangladesh. therefore, by irrigation as well as wreath of clouds, trace metals can enter into the food chain [12]. trace metals may contaminate sediment significantly at some concentrations which may be toxic to aquatic ecosystem [105, 108]. however, the concentration of trace metals cannot provide enough information to evaluate the effect on sediment due to trace metal contamination is deposited in different chemical forms which determine their mobility, toxicity and bioavailability [108, 109]. the results from various studies of metal pollution in bangladesh are summarized in table 3. asian review of environmental and earth sciences, 2019, 6(1): 47-69 55 © 2019 by the authors; licensee asian online journal publishing group table-3. metal contamination of various surface and groundwater samples in bangladesh. sampling location cr cd hg as zn cu fe co pb ni mn references surface water (mg/l) khiru river 0.054-0.175 0.005-0.008 0.004-0.005 0.012-0.033 0.082-0.324 [89] dhaleshwari river 0.13 0.001 bdl 0.20 [90] turag river bdl-0.004 0.12-0.16 0.06-0.08 1.4-2.44 0.02-0.08 [14]a meghna river 0.006-0.009 0.001-0.003 0.019-0.022 0.003-0.009 0.0005-0.0022 0.01-0.04 [91] meghna river 0.006-0.074 0.001-0.007 0.01-011 0.47-1.6 bdl bdl 0.0003-0.025 [15] balu river 0.01-0.016 0.001-0.002 0.021-0.028 0.006-0.01 0.0002-0.001 0.044-0.049 [91] balu river <0.004-8.44 <0.003-3.30 <0.0040.054 <0.0179-0.0282 0.0106-0.0191 [92] shitalakshiya river 0.004-0.02 0.001-0.003 0.017-0.029 0.001-0.009 0.0005-0.002 0.045-0.056 [91] karatoa river 0.033-0.126 0.0009-0.022 0.01-0.092 0.023-0.119 0.008-.064 0.0093-0.071 [93]a karatoa 0.002-0.009 trace trace trace-0.89 trace 0.001-0.012 trace-0.32 [94] dhaleswari river 0.379-0.501 0.005-0.008 0.0984-0.188 0.038-0.063 0.005470.00974 [95]b buriganga river 0.557-0.0645 0.007-0.0123 0.107-0.201 0.058-0.072 0.00715-0.0103 [96]b surma river 0.036-0.040 0.00259-1.443 0.0042 0.000280.0032 0.013 [31]a turag river 0.011-0.0127 0.0116-0.0195 0.00090.0151 0.001-0.0055 0.186-0.45 0.1203-0.380 2.012-3.461 0.0078-0.029 0.1282-0.1333 0.4381-0.978 [12]a depz 0.00370.0175 0.0022-0.0039 0.00250.0059 0.002-0.007 0.0146-0.0818 0.0015-0.0092 0.05-2.014 0.00370.0175 0.0160.033 0.0051-0.022 0.0049-0.0479 [97] hazaribagh canal 0.0-20.20 <0.01-0.28 0.01-1.10 0.01-2.50 <0.005-1.50 0.01-15.50 <0.0051.10 0.01-2.5 0.0-1.10 0.0-1.22 [98] vahirab river 0.001-0.006 0.0002-0.0094 0.001-.004 0.1-2.6 0.004-0.025 [39] groundwater (mg/l) feni bdl-0.005 bdl-0.011 0.1-0.5 bdl-0.015 bdl-0.01 0.1-8.46 bdl0.008 0.02-0.07 bdl-0.02 bdl-3.47 [32] noakhali bdl-0.006 bdl-0.013 0.1-0.5 bdl-0.017 bdl-0.012 0.15-3.08 bdl0.005 0.01-0.08 bdl-0.024 bdl-1.49 [32] lakshmipur bdl-0.007 bdl-0.009 0.1-3.0 bdl-0.019 bdl-0.015 0.08-8.10 bdl0.009 0.05-0.07 bdl-0.018 0.01-2.39 [32] kustia <0.002 <0.001 0.114-1.16 0.012-0.021 0.004-0.009 6.77-7.19 <0.002 <0.004-0.005 <0.002 0.69-0.74 [99] western region <0.00020.0031 0.0002-1.955 0.012-0.073 0.0002-0.0008 nd-0.0001 trace-0.001 [100] mohanpur 0.0036-0.019 0.002080.00316 0.0136-0.0159 0.0072-0.0037 [70] dhaka city <0.01 <0.001 0.00230.0033 <0.025-0.102 <0.001-0.003 <0.025 <0.001 <0.001-0.0014 0.0025<0.025 0.0063-<0.056 [101] aobserved in wet and dry seasons; bobserved in monsoon, premonson and postmonson, depz-dhaka export processing zone. asian review of environmental and earth sciences, 2019, 6(1): 47-69 56 © 2019 by the authors; licensee asian online journal publishing group chromium (cr) is one of the most health and environmental concerning metals found in earth crust and water. chromium becomes hazardous for public health if the daily intake is exceeded by who recommended value (0.05 mg/l) but the deficiency of cr can cause the disturbance of glucose, protein and lipid metabolism [110]. chromium is generally present in trivalent oxidation state (cr3+), tetravalent oxidation state (cr4+) as well as hexavalent oxidation state (cr6+). among those three states cr3+ is least toxic. hexavalent state of cr is highly toxic and is mainly responsible for different types of skin irritation like ulcerations, dermatitis, allergic skin reactions [111]. in different studies, higher concentration of cr has been documented in the surface water from last two decades table 3. chromium concentration in the water of dhaleshwary river [90, 95] balu river [92] (higher limit 8.44 mg/l), karatoa river [93] (higher limit 0.126 mg/l), buriganga river [96] hazaribagh canal [35] was higher than the who (world health organization) [42] and doe [41] recommended (0.05 mg/l) limit for drinking water. chromium concentrations in groundwater of noakhali [32] excided the doe recommended [41] value for drinking water. the main source of cr concentration in surface water has been attributed to the industrial wastes especially tannery effluent [12, 112]. however, in all cases summarized in table 3, cr concentration in groundwater is lower than the surface water as well as belongs to permissible limit. cadmium (cd) is rarely found in surface water however, in industrial arena it can be found over the danger level. cadmium is an eco-toxic metal exposes highly adverse effects on the soil overrate, biological activity of soil, plant metabolism and human and animal health [113]. a very mild concentration of cd intake can cause anemia, anosmia, cardiovascular diseases, renal problems and hypertension [114]. cadmium is used in battery, pigment and paint, plastic, ceramics and glass manufacturing industries and causes pollution when the untreated wastes of those industries are dumped into the water body. it is a health hazardous element over the concentration of 0.005 mg/l in drinking water [42]. the observed concentrations of cd are above the danger level in khiru river [89]; balu river (0.003-3.30 mg/l) [92] meghna river [91] buriganga river [96] turag river [12] as well as in groundwater from noakhali [32] and mohammadpur [70]. intense mortality rate of red tilapia has been observed due to the higher intake of cd and it also has an effect on the decreasing of sperm number [115]. the intake of cd over the permissible level through water or food causes acute and chronic illness for human and also treats as a carcinogenic agent [116]. mercury (hg) a natural occurring trace element exerts its hazardous impact on public health even a very dilute concentration. in aquatic environment, hg combines with methyl ion and forms methyl mercury which exerts its highest toxic effects [117]. as a potential toxic element, hg interferes on the production of neurotransmitter and also reduces the production of different important hormones including thyroid and testosterone [117]. the sources of hg are anthropogenic and naturogenic. the anthropogenic sources are metal processing, chemical industries, mining, sewage, fungicides etc. [118]. a study [42] reported that in absence of hg emitting source, an area can be polluted by hg due to the global hg cycle through the air and water. the concentration of hg in the turag river is in the range of 0.009-0.0151 mg/l [12] and that of in the depz area is 0.0025-0.0059 mg/l [97] both are over the safe level 0.005 mg/l [119]. last decades of previous century, arsenic (as) in drinking water was a tremendous public health threat in bangladesh. groundwater as concentration in northern and southern district of bangladesh has been found over the permissible level of safe drinking water. a plethora of arsenicosis patients have been identified over the past two decades. uptake of as over a period causes melanosis, leuko-melanosis, hyperkeratosis, cardiovascular diseases, neuropathy and cancer [120]. nowadays, the arsenicosis problem has been changed due to awareness program and safe water treatment plant conducted by who, government and different ngos, howbeit, owing to over exposure of ground water still arsenic problem in ground water is an alarming problem in bangladesh. arsenic problem is also faced by some other asian countries like india, pakistan, china, mayanmar. in surface water the concentrations of as lie in the limit of doe [41] and who [119] except korotoa river [93] and hazaribag canal [98]. however, the concentration of as in groundwater of noakhali, feni, lakshmipur, kustia, western region is highly above of the doe and who recommended drinking water standard table 3. the doe recommended [41] value of as in drinking water is 0.05 mg/l and that of by who is 0.01 mg/l [119]. in bangladesh, the main source of as is the naturogenic. this can be rationalized by the fact that the over irrigation and decreasing the ground water level owing to the lower availability of water in dry season, as get readily mixed from earth crust to the groundwater. arsenic contamination in body may decrease the production of white and red blood cells, can cause gastrointestinal irritation, weaken the heart beat and red spots on hand and feet [121]. zinc (zn) is an essential element in enzyme and protein [122]. it has a protective effect against pb and cd toxicity [123]. however, the over exposure to zn can have adverse effect in aquatic life [12] ecosystem and public health. higher accumulation of zn in body exerts toxic and carcinogenic effects and subsequently neurologic, hematological complications, hypertension, kidney and liver function disorder [124]. who recommended acceptable value of zn for drinking water is 3.0 mg/l [119]. in both surface and groundwater zn lies in well below of permissible level table 3. the source of zn is naturogenic, industrial effluent and agricultural runoff. zinc is highly mobile element. at alkaline condition, zn lead to precipitate as znco3 [116] and settle down on sediment and on plant tissue. radial oxyzen loss rate of v. serpyllifolia wetland plant can significantly decrease the mobility of zn as an essential element of plant in metal contaminated soil under flooded condition where iron plaque is formed on the root surface which hinders the mobilization of zn through the plant tissue [125]. copper (cu) is a biogenic element in hemoglobin which is necessary for the metabolism of all organisms [126]. however, the over dose of cu may cause parkinson’s disease [127]. who recommended value of cu in safe drinking water is 1.5 mg/l [119]. the concentration of cu in surface and groundwater lies below enough the permissible limit for drinking water except hazaribagh canal [98]. in hazaribagh arena more than 250 tannery industries had been operated and they used copper salts for tanning purpose. therefore, may be the concentration of cu (0.005-1.50 mg/l) was higher in hazaribagh canal. recently, tannery industries have been shifted from the hazaribagh area to a well-organized industrial area in savar and we are expecting this situation will be changed in near future. as an important element of earth, iron (fe) is found on earth crust. it is an important element in the physiology of living organisms [128]. the concentration of fe in surface and groundwater is very high than the asian review of environmental and earth sciences, 2019, 6(1): 47-69 57 © 2019 by the authors; licensee asian online journal publishing group who prescribed (0.3 mg/l) value [119] for drinking water table 3. in groundwater of fenni, laxmipur and kustia the concentration of fe in some samples is more than 8 mg/l. the source of fe in ground water is the naturogenic. in some cases fe may be mixed from industrial sources. higher concentration of fe makes the water bad tested and addled color. gorell, et al. [127] found the highest relation of parkinson’s diseases with the elevated dose of iron for over 1-20 years. the over exposure to fe causes cancer [129] diabetes [130] liver and heart diseases [131]. in contrast to the over dose, the deficiency of iron causes improper physiological metabolism of living organisms especially for women. cobalt (co) is as an essential element of vitamin b12 [132]. the concentration of co in both surface and groundwater is very low except hazaribagh industrial region (1.1 mg/l) [133]. in surface water the source of co is mainly the industrial wastes. mass population can consume co from beverage and food. co poisoning of human body may be linked with allergic dermatitis, rhinitis, asthma and lung cancer [132]. lead (pb) is a toxic heavy metal which has no known biological function [134]. pb shows very high mobility and associates with clay minerals like manganese oxide, aluminum and iron hydroxide and organic materials [135]. both surface and groundwater are contaminated by pb compared to the permissible level of drinking water table 3. the permissible level of pb in drinking water fixed by who is 0.01 mg/l [119] and by doe is 0.05 mg/l [41]. despite the lacking of heavy industrial zone, the concentration of lead in the groundwater of the southeast part of the country (feni, noakhali, laxmipur) shows raised value than the permissible level [130]. the source of pb in the groundwater of southeast part may be the naturogenic. the other sources of pb in surface and groundwater are household paint, vehicle exhausts and industrial wastes [136] lead gasoline, municipal runoffs, atmospheric deposition [137, 138] battery industries [12] scrap batteries, thermal power plants and iron industries. higher intake of pb over time may exert bad effect on nervous, digestive, haematopoietic, cardiovascular, reproductive and immunological system and kidneys [139, 140]. nickel (ni) exerts its toxicity on human health due to over consumption through food or drinking water. permissible level of ni in drinking water is 0.07 mg/l [119] and in bangladesh that is 0.10 mg/l [41]. all the surface and groundwater sample satisfy the permissible level except turag river wherein the concentration of ni is 0.128-0.133 mg/l [12]. the sources of ni are attributed to the alloy, battery and pigment industries wastes. consumption of ni through food chain or with drinking water have connection with heart and liver damage can decrease the body weight and cause skin irritation [141] dermatitis, lung fibrosis, cardiovascular diseases, cancer in the respiratory tract [142, 143] rhinitis, nasal sinusitis and nasal mucosal injury [17]. manganese (mn) forms 0.1 % of earth crust [144]. it is an essential element for animal and plant for their physiological functions and deficiency of mn may cause brutal skeletal and reproductive abnormalities for animal [126]. the who recommended value of mn in drinking water is 0.5 mg/l [119]. in different observations the concentration of mn in surface water is in the who prescribed value except turag river table 3. however, in groundwater the concentration of mn in the southeast part (feni, noakhali, laxmipur) and southwest part (kustia) of bangladesh is surprisingly above the who suggested value for drinking water table 3. the source of mn in groundwater may be naturogenic. the ingestion of higher dose with drinking water affect adversely in nervous system [145]. most of the metals are in the permissible level recommended for drinking water. heavy metals concentration is slightly higher in the industrial region. most of the authors described that the higher concentration of metals are attributed to the untreated industrial effluent, municipal wastes, and agricultural runoff. however, the ground water as concentration in the southeast and northern region is over permissible limit for drinking water. this is due to the consequence of naturogenic activity. 2.2.2. ions some ions are essential for plants however; overdoses of those may cause adverse effect. some major ions those are reported from surface and groundwater have been tabulated in table 4. main source of na+ in the river water and in sediment may be the untreated or partially treated industrial effluent which is dumped into the river. different types of sodium salt are used by industries (mainly tannery, dying) for their production purpose. the excess amount of sodium salt in effluent potentially pollutes water body unless proper treatment accounted. if sodium concentration is higher as combined with chlorine and sulfate then the water would not be suitable for irrigational use [128]. sodium polluted irrigated water makes the soil puddling and therefore, decreases the water intake capability and becomes hard which makes seed germination difficulties [149]. higher concentration of sodium may impose osmotic stress on the aquatic biota [149]. therefore, the population of biota may be decreased which makes a poor aquatic ecosystem. magnesium is the key component of chlorophylla, plays an important role in ecosystem. higher concentration of mg2+ makes hard water which creates difficulties in household washing. like mg2+, ca2+ also creates problem in household washing. long time ingestion of excess calcium may cause hypercalcmia, urinary tract calculi, calcification in soft tissues like kidneys and in arterial walls and suppression of bone remodeling [150]. the source of fluoride is naturogenic character. beside this pesticide, fertilized, industrial wastes and agricultural runoff, cosmetics enhance the concentration of fluoride in wetland. it consists in the environment by combining with other elements and minerals as fluorite and fluorapatite [151]. fluoride is an essential element for human, plays an important role for teeth and bones structure. however, more than 1.5 mg/l intake of fluoride causes dental and skeletal fluorosis [152]. it also causes non-skeletal fluorosis when affected the soft tissues in the organs such as endocrine glands, thyroid, liver, kidney and other systems of the body [151]. like fluoride ion, chloride ion presents in different rocks. it has a high affinity towards metals. therefore, it has a high concentration in ground water, hard water and metal polluted water. the other sources of chloride in surface and groundwater might be chlorinated pesticides and wastes from industries. asian review of environmental and earth sciences, 2019, 6(1): 47-69 58 © 2019 by the authors; licensee asian online journal publishing group table-4. contamination by ions of various surface and groundwater samples in bangladesh. sampling points na+ k+ ca2+ mg2+ clfco3 2no3 so4 2po4 3references surface water (mg/l) buriganga river 9.4-39.3 4.2-10.6 17.2-34.0 6.4-22.7 39.6-98.3 12.9-34.5 2.0-9.8 1.7-6.1 [146] turag river 13.2-32.3 7.6-20.4 11.2-25.5 2.0-5.7 80.7-147.4 0.030.6 1.0-4.9 101.2-148.9 9.9-26.1 [147] dhaka district 21.38-214.0 2.10-13.50 22.09-151.0 1.21-7.58 [98] karatoa river 0.0125-0.025 0.00850.0215 0.024-0.071 0.00390.0301 trace 3.08-25.92 1.13-2.56 [94] depz 0.27-0.66 [97] northwest region 0.01-1.65 0.007-0.096 0.004-0.275 [69] hazaribagh canal 2211.76 44.49 244.1 48.47 2465.0 44.80 546.0 [101] hazaribagh canal 108-6840 0.1-194.00 5-1163 0.07-52.1 [98] groundwater (mg/l) sylhet city 0.10-48.30 0.02-26.52 0.69-96.6 0.27-64.02 1.45-142.0 [148] northwest region 0.36-1.13 0.17-0.48 0.64-2.32 1.05-3.81 [69] kustia 3.27 0.268 0.98 0.424 0.23 [99] mohanpur 13.1-151.2 0.08-2.8 [70] pabna district 0.43-1.59 0.02-2.95 0.67-6.29 0.23-1.23 1.13-7.75 nd [99] dhaka city 28.37-42.96 1.67-2.27 30.75-50.14 9.04-14.82 9.44-64.09 0.40-5.57 0.18-9.21 [101] khulna 3.91-73.08 0.01-0.78 0.70-8.28 0.69-8.00 0.82-84.62 0.00-0.11 0.00-0.57 0.00-0.48 [71] *nd=not detected. asian review of environmental and earth sciences, 2019, 6(1): 47-69 59 © 2019 by the authors; licensee asian online journal publishing group phosphate ion is sparingly soluble in water and adsorbs with clay particles and precipitates as fe, al and ca compounds. the sources of po4 3in the surface water may be fertilizer and industrial wastes. concentration of po4 3in surface water of dhaka region [98, 146] shows slightly higher than the other part of country which indicates mainly industrial effluent is the main source of po4 3pollution. safe limit of phosphate in drinking water has been prescribed by who is 5.0 mg/l [23]. soft drinks contain almost about 170 mg/l phosphorus which is a potential threat for public health. the possible sources of nitrogenous ions are fertilizer, industrial effluent and human excreta [153] and agriculture runoff. excessive nitrate content in drinking water causes infant methemoglobinemia (blue baby) [154]. nitrate is not itself carcinogenic but it form n-nitroso compound in stomach which is carcinogen [155]. 2.3. pesticides the residue of pesticides from agricultural and non-agricultural sector increases from last few decades due to the enormous use for higher agricultural farming. surface water is more vulnerable to accept the residual pesticides due to rain and flood. nowadays, the contamination of pesticides residue is more common concern worldwide as they expose their toxicity to human animal and living organism by penetrating into food cycle and water cycle. some common pesticides which are reported in different articles are illustrated in table 5. table-5. level of pesticides in surface water. sampling location no of observation detected pesticides concentration (µg/l) mean recovery (%) references total polluted buriganga river 3 3 0 chlorpyrifos diazinon 484.0 19.0 [156] lakes in rangpur 5 5 5 5 5 1 chlorpyrifos carbofuran carbaryl 0.544-0.895 0.949-1.671 nd-0.195 86.25 90.13 92.65 [157] savar and dhamrai 5 1 malathion nd-105.2 81.25 [158] 5 1 diazinon nd-0.90 96.38 5 2 carbaryl nd-18.1 93.75 5 2 carbofuran nd-198.7 85.00 savar 12 0 methoxychlor nd 89.3 [156] 12 0 ddt nd 91.45 12 0 chlorpyrifos nd-9.31 94.54 12 1 diazinon nd-7.86 88.32 12 0 ethion nd 93.12 12 0 fenthion nd-56.3 85.98 12 3 fenitrothion nd-33.41 89.25 12 0 malathion nd-59.9 91.62 12 0 parathion nd-6.23 90.41 12 2 carbaryl nd-6.3 92.51 12 1 carbofuran nd-43.2 93.41 12 3 cypermethrin nd-80.5 87.32 dhanmondi lake 3 diazinon 28.0 [156] 3 chlorpyrifos 629.0 kollanpur lake 3 diazinon 19.0 3 chlorpyrifos 982.0 ramna lake 3 diazinon nd 3 chlorpyrifos 177.0 ponds in dhaka city 30 diazinon nd-33.0 30 chlorpyrifos nd-108.0 feni ddt 4.16 [159] heptachlor nd nawabganj ddt 3.01 heptachlor nd rajshahi ddt 0.133 heptachlor nd nator ddt nd heptachlor 5.24 comilla ddt 8.29 heptachlor nd dde 4.06 sunamganj ddt 5.60 heptachlor 5.04 madaripur ddt nd heptachlor 5.14 bandarban ddt nd heptachlor 5.08 pagla, narayanganj 8 3 diazinon nd-2.144 [160] 8 3 carbofuran nd-2.181 savar heptachlor 1.4795 [36] * bold concentrations are unsafe for human. chlorpyrifos is an organophosphate pesticide used to kill insecticides and worms. the concentration of chlorpyrifos is very high (484.0 μg/l) in buriganga river [156]. sumon and coauthors [161] reported that the chlorpyrifos is moderate to high chronic to fish in the spray spot and about its 10.0 m periphery. during dry asian review of environmental and earth sciences, 2019, 6(1): 47-69 60 © 2019 by the authors; licensee asian online journal publishing group season, the burignga river water turn into dark color and according to the fisherman there is no fish in the metropolitan region [8]. this high concentration of chlorpyrifos gives evidence in favor of biological death of the buriganga river. chlorpyrifos level reported in the lake of ramna, kollanpur, dhanmondi is also high table 5. diazinon is also an organothiophosphate pesticide used as pest control especially for cockroach, fleas and ant. the level of diazinon in the buriganga river, dhanmondi lake and kollanpur lake is higher than the australian permissible limit (3 μg/l) for health [162]. however, in rural area of bangladesh the concentration of ddt, heptachlor is much higher than chlorpyrifos table 5. ddt is an organochlorine pesticide used in farming and household insecticidal killing. authors did not find detectable ddt level in the water samples collected from bandarban, nator, madaripur. this may be due to the prohibition of marketing and use of chlorinated pesticide according to the bangladesh environment conservation act 1995. organophosphate pesticides are nowadays, mostly using in bangladesh although some unethical organochlorine pesticides are still available. therefore some authors detected higher ddt level in the feni, nawabjong and comilla region [159]. carbofuran is a toxic carbamate pesticide used in farming especially potato cultivation. in savar and dhamrai region [158] carbofuran has been detected very higher level (198.7 μg/l) than prescribed by the austrlian guideline (5 μg/l) [162]. an article [163] reported higher concentration of cypermethrin in the sample collected from savar which is used in agricultural field and by rain and flood gets mixed in water body. cypermethrin is a hydrophobic chemical and thus precipitate on sediment. as a consequence cypermethrin exposes long term toxicity to the water cycle [164]. 2.4. pathogenic pollution pathogenic pollution is one of the concerning diseases causing sources in developing and developed countries which is mainly spread through water and foods. the subsequent effect of pathogenic pollution is different types of diseases including diarrhea, vomiting, dysentery, typhoid, hepatitis etc. in bangladesh pathogens are attributed to the 80 % of all diseases [16]. according to gob-unicef, about 0.3 million children under five die every year of which one third in city slums and quarter settlement [165]. microbial waterborne diseases also acute in developed countries. in usa, every year 0.56 million people affected by severe waterborne diseases and 7.1 million suffer from mild to moderate infection [166]. some pathogenic bacterial count observed by different authors in different regions of bangladesh is presented in table 6. table-6. pathogenic bacterial count in surface and groundwater. sampling location vibrio cholerae pseudomonas spp heterotrophic bacteria e. coli cfu/100ml total coliform cfu/100 ml fecal coliform cfu/100 ml references dhaka district 1.1× 1038.7× 106 225-6.8×105 [98] turag river 75-7500 25-2.0×104 [167] buriganga river 10-55000 125-8.0×104 dhaleswari river 4-4.0×103 50-6.5×103 khulna area pond 37 4-37 220-1.35×104 <1-4.0×103 12-5.0104 [168] buriganga river 1.0 × 108 – 3.0 × 1011 1.1× 103 >2.4 ×105* 1.1× 103 >2.4 ×105* [169] mirpur 0-7.5×104 0-4.6 ×104 1×1010-9.4×109 [170] satkhira 2.74×1023.32×102 1.55×1031.95×104 9.50×1021.73×103 [171] ponds in dhaka <19.05×104 [172] turag river <18000 [12] souther part of bandladesh 0.0-448 [173] rajshahi 184 [174] groundwater matlab 1-2000* [175] rajshahi 5 [174] potenga 6.5×103 [176] bhatiari 2.0×1041.2×105 [176] kumira 1.7×1043.0×104 [176] *unit is mpn/100ml (most probable number). total coliform and fecal coliform are shown highest count in all of the samples which indicate the samples are polluted by sewage and human as well as animal feces. e. coli is a subgroup of fecal coliform its concentration is also high in all of the samples. e. coli 0157:h7 strains in drinking water can cause abdominal pain, bloody diarrhea and hemolytic uremic syndrome [177]. the presence of coliform bacteria in the surface and groundwater samples indicates the presence of disease causing agent in the water. heterotrophic bacteria count has been used for counting all aerobic and anaerobic bacteria shows higher bacterial count in a pond of khulna [168] and dhaka region [98]. they are not prone to pathogenic but some of them like pseudomons are causing infectious to skin and lung and other type like aeromonas cause gastroenteritis [178]. heterotrophic bacteria are considered as an indication for measuring the coliform in water [179]. asian review of environmental and earth sciences, 2019, 6(1): 47-69 61 © 2019 by the authors; licensee asian online journal publishing group table-7. pharmaceuticals concentration in surface water of the old brahamaputra river [185]. pharmaceuticals uses [186, 187] concentration ng/l n n nh2nh2 och 3 och3 och3 trimethoprim antibiotic, antibacterial, primarily used for urinary tract infections <lod-17.20 n n ch3 oh o2n metronidazole antibiotic, antiprotozoal, nitromidazole 0.05-13.51 n o nh2 carbamazepine anti-epileptic, neuropathic pain reliever, anti-psychotic <lod-8.80 o o oh oh oh o o o o oh och3 n ch3 ch3 oh o erythromycine antibiotic, macrolide, human and veterinary application <lod-6.46 s nh n n o o nh2 ch3 ch3 sulfamethazine antibiotic, sulfadrug, broad spectrum antibacterial, human and veterinary application <lod-4.19 s nh o o nh2 n o ch3 sulfamethoxazole antibiotic, sulfa drug, broad spectrum antibacterial, human and veterinary applications <lod-7.24 s nh n n o o nh2 sulfadiazine antibacterial, primarily used for urinary tract infections <lod-0.58 s nh o o nh2 n n sulfamethizole antibiotic, antibacterial, primarily used for urinary tract infections, intestinal infections, pneumonia <lod-11.35 *lod = limit of detection. 2.5. pharmaceuticals pollution undoubtedly, pharmaceuticals are revolutionary for easy and safe life. however, their occurrence in surface water can exert negative impacts for animals and ecosystem. unlike developed countries due to insufficient health services and lack of awareness, people buy pharmaceuticals from drug store without physician’s prescription, asian review of environmental and earth sciences, 2019, 6(1): 47-69 62 © 2019 by the authors; licensee asian online journal publishing group substantially, misuse the dose and real need of drugs. total doses of pharmaceuticals after administration are not always completely undergoing metabolic transformation by gut microbes or host enzymes [180] and used up by our immune system and find their way into natural water bodies. the hospital and clinic waste treatment process in bangladesh is very limited and most cases absent in rural area and consequently accumulated in surface and ground water. in bangladesh formulated feeds and in some cases poultry droppings are used for aquaculture and those are enriched with pharmaceuticals [181] and accumulating in the water bodies. huerta-fontela [182] and coauthors found 55 commonly prescribed pharmaceuticals and hormones in raw water used for drinking water supply and 5 of them were unable to remove up to a reasonable limit via standard water treatment procedures. the essential and frequently used pharmaceuticals in bangladesh are sulfamethoxazole, sulfamethazine, trimethoprim, erythromycin, penicillin, metronidazole and carbamazepine. a group reported that approximate 13 % of consumed carbamazepine is discharged from the body through excreta and urine without any substantial structural modification [183]. there are only few articles have been reported the pharmaceuticals (table 7) in surface water in bangladesh [181, 184]. metronidazole is one of the frequently used pharmaceuticals in bangladesh and detected in all of the sampling points in brahamaputra river [181]. the possible sources of metronidazole in surface water are human excreta, veterinary and fish farming [188]. among the sulfonamides drugs, the concentration of sulfamethizole was observed in higher concentration in brahamaputra river (11.35 ng/l) [181] and rajshahi (10.81 ng/l) [184]. sulfonamides show quite persistent characteristic in aquatic system owing to their hydrophilic nature and can be transported far from their point of origin [189, 190]. the occurrence of pharmaceuticals in water bodies cans bioaccumulate on nontargeted organism e.g. mollusks, fishes and aquatic biota even at very low concentrations [191, 192] and affect the aquatic ecosystem. the increasing use of antibiotics is concerning issue worldwide and intensify to create the bacterial resistant strains (known as superbug) for human and animal health [193, 194]. 2.6. naturogenic pollution in conjugation with anthropogenic sources, water has been polluting from the naturogenic actions. arsenic is a natural element in earth crust can mix with underground water [195] and causes health risk. nitrogen also mixed with water during thunderstorm. rain and flood washed away waste materials and drained into river which may pollute water body. river is also polluted by bank erosion. volcanic eruption emits different metals which get mixed into water and makes the water polluted. waste materials from different ore mine pollute nearby water system by adulteration of different ore. the chemical interaction of water-rock in aquifers contributes to pollution of ground water [196]. pyrite and marcasite are common components in coal mine. pyrites when exposed to the environment get hydrolysis and produce sulfuric acid and acidify the water body [197]. organic matter and nutrients leaching from soil surface to ground aquatic level may change the physical and chemical composition of water through biological process [196]. rain and drought can change the water quality by diluting and concentrating water. 2.7. statistical study statistical studies allow us to discuss and rationalize the analytical data and their interrelation, coexistence as well as distribution of pollutants in study area. it becomes noteworthy for understanding the impact of pollution on ecosystem and puts forward important and significant information about calculating ecological risk. 2.7.1. pearson’s correlation the degree of interdependency of one parameter to another is illustrated by pearson’s correlation tool [198] and it explains the deep root of mutual interaction of parameters in the study area. understanding of pollutant source types typically becomes refulgent through correlation study. the result of correlation study in a specific area may be inconsistent with the result of other study where different environment may exist. in the buriganga river water cod shows significant positive correlation (p < 0.01) with ph, salinity, tds and ec and significant negative correlation with do as well as the metal cr demonstrates significant positive correlation with cd, zn and cu [8]. the results obtained from the shitalakkhya rive reflected that tds has positive correlation with salinity, ec and cod [10]. in karnaphuli river, pb is insignificantly and negatively correlated with as and positively correlated with cr and cd [199]. correlation matrix of bod, tds, tss, po4 3in tannery and textile effluent and adjacent river where the effluent has been dumped demonstrates strong positive correlation [63]. alkali reflects strong correlation (p < 0.05) with cod and clwhich reveals that they are originated from similar sources [35]. the correlation of do and ph in the halda river is significant (r = 0.663) and that of in the karnofuli river during the same season is positive but insignificant. in ground water of that region do is negatively correlated with ph (r= -0.04) [68] which indicates that the correlation is completely depends on surrounding environment and sources. a correlation study of the mouri river visualized that temperature, ph, hardness, ta, do, free co2 and sulphate were in positive correlation [64]. 2.7.2. principal component analysis principal component analysis (pac) is a useful tool used to sort out patterns in a data set and to eliminate redundancy in univariate analysis from a large set of data [200]. traditionally, pac reduces dimensionality of data by linear combination of original data through creating the uncorrelated set of variables from the original variables. the eleven variables of twenty sampling site in the mohonpur subdistrict under rajshahi district ascribed that the two principle components cover most (almost 72.53 %, considered eigenvalues ≥ 1) of the variables [70]. bhuiyan and coauthors studied the surface water quality near dhaka district through 10 sampling sites and for 16 variables. they executed varimax method with kaiser normalization for studding pc and found that five pc cover almost 88 % of variables [35]. asian review of environmental and earth sciences, 2019, 6(1): 47-69 63 © 2019 by the authors; licensee asian online journal publishing group 2.7.3. cluster analysis cluster analysis (ca) studies allow us to find out the groups according to their similarities [201] like their sources, distribution and chemical behavior. the outcome of ca is expressed through dandrogram. most generally, hierarchical cluster analysis and ward’s linkage method used to classify the samples. ca performs a series of multivariate methods to determine the appropriate groups of data [202]. hierarchical cluster analysis has been done for eleven samples from mohonpur under rajshahi district and the output shown in dendrogram falls into two main clusters like cuslter a and b [70]. cluster a showed a close association of as, mn, cd, total hardness, pb, tds and ec and cluster b formed by total alkalinity, no3 -, cland ph. molla and coauthors also applied ca among ten sampling sites and find two major clusters. this study put forward a message that, only two sampling points are suitable enough for understanding the environment of mohonpur area. ten sampling points around dhaka district has been grouped by ca and found into two main clusters [35]. cluster 1 possesses three sampling sites those are more polluted and rest of the sampling sites are less polluted and comprise in cluster 2. bhuiyan also implied ca for sixteen variables and grouped into two clusters. tds, turbidity, do, cl-, temperature, cod and so4 2lie in cluster 1 and tss, ec, alkalinity, ph, po4 3-, bod, fecal coliform, and total coliform lie in cluster 2. incorporation of coliforms and bod in similar cluster means that the growth of bacteria enhances the raising bod level. 3. handicap in sampling and analysis surface water analysis does not carry any worthy value if the sampling, storing procedures and analysis do not follow appropriate method. ascertaining the quality of surface water depends on the sampling site selection. a sample site is usually an infinitesimally small part of water body. therefore, the chemical composition and quality of surface water is greatly influenced by the selection of sampling sites. the sample selection site should be representative of the water body being investigated. sampling sites selection of mouri river [64] did not explain well enough by providing information whereas the sampling sites selection in buriganga river [20] industrial zone of dhaka [97] were explained along with sufficient information. the study period for environmental research conveys a significant essence to evaluate the pollution status of water body. however, the surface and ground water evaluation study of chittagonj region did not mention the time period [68]. grab and integrated sampling methods are applied for representative sampling for surface water [203]. depth of sampling is accounted in both of the aforementioned sampling processes to understand the hydrochemistry. most of the surface and ground water evaluation studies did not disclose the sampling methods and sampling depth. this is one of the significant handicaps of water quality analysis. the geology is different in the different part of bangladesh for example in northern part we have a flat land but in the east and northeast we have hill track area. the water level would differ from region to region. consequently to realize the true facts authors should disclose the sampling depth. sampling in nontransparent polyethylene bottle has been recommended by who and the collected sample must be stored at 4 oc [204]. a proper preservation process was followed by islam and coauthors but they said the sampling bottles was washed by detergent solution whereas they did not mention the type of detergent [10]. the detergent which is used for washing purpose shold be nonionic [203]. collected samples should be carried to the laboratory by using ice carrier and for microbial analysis the time interval of sample collection and analysis must not exceed 24 hours [204]. microbial analysis was performed for the burigang river [16] turag river [12] but the authors did not mention about the analysis time as well as any standard procedure however, such study performed for dhaka municipal water followed a standard procedure [170]. some parameters must be measured in the spot whenever samples are collected for example, do, ph, turbidity etc. but in some article authors did not mentioned about their analysis strategies [20, 39, 205]. flowing water generally possesses unique character and demands special care in sampling. obtaining consistent results and make them rationalize flowing stream water should be collected by isokinetic, depth-integrated or nonisokinetic process [206]. 4. environmental policies in bangladesh the law for conserving environment in bangladesh was first adopted in 1995 although achieved the independence in 1971. this delay does not really mean that there was no concern about environment in bangladesh. the environment protection was reflected in national development policy [207] and five year policy 1973-78 [1]. national environment policy 1992 was the first draft for conserving the environment and thereafter became law in 1995 under the name bangladesh environment conservation act 1995 [208] which is operated under department of environment (doe). permissible standard for 26 health hazardous substance in drinking water was fixed in march 1997 and another 27 substance was fixed as water quality monitoring parameters. the quality standard for industrial waste water has been also mentioned under the environmental quality standard 1997 [209]. in 2003 the standard value for total zinc in drinking water has been established and other three substances added into the monitoring parameters. environmental court act 2000 was established to support the beca 1995 and for the trial against offences regarding environmental pollution. in national water policy (nwp) 1999 have 50 clauses to augment the protection, restoration and preservation of natural habitats in wetlands, mangroves and other forests. all the policies, ordinances and acts are reviewed time to time for ensuring the safe and sound environment. however, inappropriate implementation and lack of observation due to administrative complexity, inadequate manpower and insufficient budget, above all lack of awareness, skill and seriousness the efficiency has questioned tremendously. as a result, the surface and ground water in industrial cities has polluted extremely. bangladesh is a low laying country beside bay of bengal. most of the river generated from the upper riparian neighboring countries india and nepal. to protect the water security, the government of bangladesh maintains the treaty and agreement with india, nepal and bhutan. during dry season (january-may) the water flow in hardinge bridge (a bridge on padma river in pabna, western part of bangladesh) region decline tremendously after construction of farakka barrage on ganges river in india. the ecosystem of padma river and the lifestyle of the people on the padma catchment area affected extremely especially who are depended on fishing due to lack of asian review of environmental and earth sciences, 2019, 6(1): 47-69 64 © 2019 by the authors; licensee asian online journal publishing group certain water level. also the agriculture has been hindered due to the decline of ground water level. an agreement on ganges river water was signed between bangladesh and india to preserve the navigation and a certain water flow during dry season (january-may) in 1996 [210]. tista is the fourth transboundary rive between bangladesh and india [211]. india have planned to construct at least 30 hydropower project by a series of cascade damn which will greatly decline the flow of tista water [211]. already india control the water flow by tista barrage in gazaldoba point and providing water in the northern part of west bengal [212]. government of bangladesh diplomatically tried to make an agreement from 2000 to get sufficient water flow in tista river. 5. conclusion industries are the main culprit for both surface and groundwater pollution in bangladesh. groundwater arsenic pollution in northern and southeastern part of the country is due to the naturogenic reason. although sufficient data is not available, the pharmaceutical and hormone pollution in surface water due to the increasing use of drugs for human, animal and aquaculture project is concerning and prone to creating bacterial resistant strain for human and animals. surface water in industrial zone videlicet dhaka and chittagong are mostly polluted however, in remaining rural districts is till now pretty fresh. the peripheral rivers of dhaka district are polluted by cod, bod, dye and heavy metals (most commonly cr, cu and zn) according to doe and who. people are not aware enough to protect the hydrological balance. although, every year people are suffering from water borne diseases but adequate data are not available. government should raise the awareness throughout the country including rural part about the worthiness of fresh water in our daily life and at the same time should imply strictly the policies and law to protect the water for future generation. references [1] fys, "the first five year plan (1973-1978); planning commission, government of bangladesh," 1973. [2] wb (world bank), "bangladesh: more and better jobs to accelerate shared growth and end extreme proverty: a systematic country diagnostic," washington, d.c, p. 5, 2015. [3] bbs (bangladesh bureau of statistics), "gross domestic product of bangladesh 2016-17," people's republic of bangladesh, pp. 1-9, 2017. [4] wfb (world factbook), economic overview: bangladesh. usa: central intellgence agency, 2018. [5] m. sarkar, j. islam, k. ahmed, a. rahman, and b. begum, "evaluation of transboundary impact on air pollution in a rural area shyamnagar, bangladesh," mesopotamia environmental journal, vol. 2, pp. 15-21, 2015. [6] a. ommi, f. emami, n. zíková, p. k. hopke, and b. a. begum, "trajectory-based models and remote sensing for biomass burning assessment in bangladesh," aerosol and air quality research, vol. 17, pp. 465-475, 2017. available at: https://doi.org/10.4209/aaqr.2016.07.0304. [7] m. sarkar, a. rahman, and n. bhoumik, "remediation of chromium and copper on water hyacinth (e. crassipes) shoot powder," water resources and industry, vol. 17, pp. 1-6, 2017. available at: https://doi.org/10.1016/j.wri.2016.12.003. [8] m. sarkar, a. l. rahman, j. islam, k. ahmed, m. uddin, and n. bhoumik, "study of hydrochemistry and pollution status of the buriganga river, bangladesh," bangladesh journal of scientific and industrial research, vol. 50, pp. 123-134, 2015. available at: https://doi.org/10.3329/bjsir.v50i2.24353. [9] k. ahmed, a. rahman, m. sarkar, j. islam, i. jahan, m. moniruzzaman, b. saha, and n. bhoumik, "assessment on the level of contamination of turag river at tongi area in dhaka," bangladesh journal of scientific and industrial research, vol. 51, pp. 193-202, 2016. available at: https://doi.org/10.3329/bjsir.v51i3.29431. [10] j. b. islam, m. sarkar, a. l. rahman, and k. s. ahmed, "quantitative assessment of toxicity in the shitalakkhya river, bangladesh," the egyptian journal of aquatic research, vol. 41, pp. 25-30, 2015. available at: https://doi.org/10.1016/j.ejar.2015.02.002. [11] m. rahman, seasonal physico-chemical attributes of the river buriganga, turag and balu, bangladesh. jahangirnagar university journal of biological sciences, vol. 3, pp. 9-16, 2016. [12] m. sarkar, j. islam, and s. akter, "pollution and ecological risk assessment for the environmentally impacted turag river, bangladesh," journal of materials and environmental science, vol. 7, pp. 2295-2304, 2016. [13] s. roy, "water quality of narai canal and balu river of dhaka city: an impact of industrialization," journal of the bangladesh agricultural university, vol. 12, pp. 285-290, 2016. [14] m. islam, t. tusher, m. mustafa, and s. mahmud, "effects of solid waste and industrial effluents on water quality of turag river at konabari industrial area, gazipur, bangladesh," journal of environmental science and natural resources, vol. 5, pp. 213-218, 2013. available at: https://doi.org/10.3329/jesnr.v5i2.14817. [15] m. hassan, m. a. t. rahman, b. saha, and a. k. i. kamal, "status of heavy metals in water and sediment of the meghna river, bangladesh," american journal of environmental sciences, vol. 11, pp. 427-439, 2015. available at: https://doi.org/10.3844/ajessp.2015.427.439. [16] m. l. saha, m. r. khan, m. ali, and s. hoque, "bacterial load and chemical pollution level of the river buriganga, dhaka, bangladesh," bangladesh journal of botany, vol. 38, pp. 87-91, 2009. available at: https://doi.org/10.3329/bjb.v38i1.5128. [17] m. mondol, a. chamon, b. faiz, and s. elahi, "seasonal variation of heavy metal concentrations in water and plant samples around tejgaon industrial area of bangladesh," journal of bangladesh academy of sciences, vol. 35, pp. 19-41, 2011. available at: https://doi.org/10.3329/jbas.v35i1.7968. [18] h. zakir and n. shikazono, "zinc pollution level in sediments of old nakagawa river, tokyo, japan," presented at the aip conference proceedings. aip, 2008. [19] v. premlata, "multivariate analysis of drinking water quality parameters of lake pichola in udaipur, india. in biological forum. 2009. satya prakashan," 2009. [20] a. saifullah, "investigation of some water quality parameters of the buriganga river," journal of environmental science and natural resources, vol. 5, pp. 47-52., 2013. [21] r. s. lokhande, p. u. singare, and d. pimple, "study on physico-chemical parameters of waste water effluents from taloja industrial area of mumbai, india," international journal of ecosystem, vol. 1, pp. 1-9, 2011. available at: https://doi.org/10.5923/j.ije.20110101.01. [22] m. i. sabit and m. a. ali, "pollution of water bodies within and around dhaka city: the case of gulshan lake," journal of civil engineering (ieb), vol. 43, pp. 29-39, 2015. [23] who, guidelines for drinking water quality-1, recommendations, 4th ed. geneva: world health organization, 2011. [24] m. rahman and d. bakri, "a study on selected water quality parameters along the river buriganga, bangladesh," iranica journal of energy & environment, vol. 1, pp. 81-92, 2010. [25] a. l. rahman, m. islam, m. hossain, and m. ahsan, "study of the seasonal variations in turag river water quality parameters," african journal of pure and applied chemistry, vol. 6, pp. 144-148, 2012. available at: https://doi.org/10.5897/ajpac12.023. [26] s. islam and g. azam, "seasonal variation of physicochemical and toxic properties in three major rivers; shitalakhya, buriganga and turag around dhaka city," bangladesh journal of botany environmental science, vol. 7, pp. 120-131, 2015. asian review of environmental and earth sciences, 2019, 6(1): 47-69 65 © 2019 by the authors; licensee asian online journal publishing group [27] m. s. sultana, m. s. islam, r. saha, and m. al-mansur, "impact of the effluents of textile dyeing industries on the surface water quality inside dnd embankment, narayanganj," bangladesh journal of scientific and industrial research, vol. 44, pp. 65-80, 2009. available at: https://doi.org/10.3329/bjsir.v44i1.2715. [28] s. karn and h. harada, "surface water pollution in three urban territories of nepal, india, and bangladesh," environmental management, vol. 28, pp. 483-496, 2001. available at: https://doi.org/10.1007/s002670010238. [29] h. m. amzad, m. kabir, and s. salehuddin, "determination of toxic toluene, xylene and cumene in different lake waters," international journal of environmental research, vol. 4, pp. 341-346, 2010. [30] m. mottaleb, m. abedin, and m. islam, "determination of volatile organic compounds in river water by solid phase extraction and gas chromatography," journal of environmental sciences, vol. 16, pp. 497-501, 2004. [31] m. j. alam, m. islam, z. muyen, m. mamun, and s. islam, "water quality parameters along rivers," international journal of environmental science & technology, vol. 4, pp. 159-167, 2007. available at: https://doi.org/10.1007/bf03325974. [32] m. ahmed, m. haque, and m. rahman, "physicochemical assessment of surface and groundwater resources of noakhali region of bangladesh," journal of chemical science and technology, vol. 1, pp. 1-10, 2011. [33] s. m. tareq, m. rahaman, s. rikta, s. n. islam, and m. s. sultana, "seasonal variations in water quality of the ganges and brahmaputra river, bangladesh," jahangirnagar university environmental bulletin, vol. 2, pp. 71-82, 2013. available at: https://doi.org/10.3329/jueb.v2i0.16332. [34] m. a. rahman and m. huda, "study of the seasonal variations in physicochemical and biological aspects of the padma river at paturia ghat, manikganj," jahangirnagar university environmental bulletin, vol. 1, pp. 55-66, 2013. [35] m. a. bhuiyan, m. rakib, s. dampare, s. ganyaglo, and s. suzuki, "surface water quality assessment in the central part of bangladesh using multivariate analysis," ksce journal of civil engineering, vol. 15, pp. 995-1003, 2011. available at: https://doi.org/10.1007/s12205-011-1079-y. [36] m. islam, s. haque, m. chowdhury, m. rahman, and z. fardous, "monitoring of organochlorine pesticide residues in surface water samples of the agricultural field of bangladesh," journal of subtropical agricultural research and development, vol. 5, pp. 357360, 2007. [37] j. alam, a. hossain, s. khan, b. banik, m. r. islam, z. muyen, and m. h. rahman, "deterioration of water quality of surma river," environmental monitoring and assessment, vol. 134, pp. 233-244, 2007. available at: https://doi.org/10.1007/s10661-007-9612-7. [38] spbb, "statistical pocket book of bangladesh, bangladesh bureau of statistics, dhaka, chapter ii," people's republic of bangladesh, p. 82, 2010. [39] f. ahmed, m. aziz, m. alam, m. hakim, m. khan, and m. rahman, "impact on aquatic environment for water pollution in the vahirab river," international journal of engineering science, vol. 4, pp. 56-62, 2015. [40] s. islam and m. islam, "status of water quality in the dhaleshwari river and its effect on aquatic organism," journal of environmental science and water resources, vol. 1, pp. 192-201, 2012. [41] doe, department of environment, government of people’s republic of bangladesh. bangladesh: the environment conservation rules, 1997. [42] who (world health organization), a report published jointly by the un environment program. geneva: the international organization and the world health organization, 2003. [43] m. t. sikder, y. kihara, m. yasuda, y. mihara, s. tanaka, d. odgerel, b. mijiddorj, s. m. syawal, t. hosokawa, and t. saito, "river water pollution in developed and developing countries: judge and assessment of physicochemical characteristics and selected dissolved metal concentration," clean–soil, air, water, vol. 41, pp. 60-68, 2013. available at: https://doi.org/10.1002/clen.201100320. [44] h. a. hawkes, the ecology of waste water treatment: elsevier, 2013. [45] o. chukwu, "analysis of groundwater pollution from abattoir waste in minna, nigeria," research journal of diary science, vol. 2, pp. 74-77, 2008. [46] usepa, manual on monitoring water quality. usa, 841-b-97-003: environmental protection agency, 1997. [47] s. k. golfinopoulos, m. n. kostopoulou, and t. d. lekkas, "volatile halogenated organics in the water supply system in athens, greece," water research, vol. 32, pp. 1811-1818, 1998. available at: https://doi.org/10.1016/s0043-1354(97)00404-1. [48] a. d. nikolaou, s. k. golfinopoulos, m. n. kostopoulou, g. a. kolokythas, and t. d. lekkas, "determination of volatile organic compounds in surface waters and treated wastewater in greece," water research, vol. 36, pp. 2883-2890, 2002. available at: https://doi.org/10.1016/s0043-1354(01)00497-3. [49] s. slaets, f. adams, and f. laturnus, "gc coupled to mip aes applied to the speciation analysis of volatile halocarbons," lc-gc international, vol. 11, pp. 580-586, 1998. [50] s. fondekar and r. gupta, "determination of hydrocarbons in aquatic systems and sediments," journal of marine pollution bulletin, vol. 8, pp. 201-206, 1984. [51] r. sacks and m. akard, "high-speed gc analysis of vocs: tunable selectivity and column selection. part 2," environmental science & technology, vol. 28, pp. 428a-433a, 1994. available at: https://doi.org/10.1021/es00058a003. [52] a. h. chowdhury and m. zaman, "impact of power plants effluent on the zooplankton," 1999. [53] apa, standart methods for the examination of water and waste water. washington: american public health association, 1989. [54] a. h. chowdhury and m. akber, "study of impacts of oil spill on the sundarbans mangrove forest of bangladesh," journal of asiatic society of bangladesh, science, vol. 41, pp. 75-94, 2015. [55] k. islam and m. hossain, "effect of ship scrapping activities on the soil and sea environment in the coastal area of chittagong, bangladesh," marine pollution bulletin, vol. 17, pp. 462-463, 1986. available at: https://doi.org/10.1016/0025-326x(86)90836-2. [56] j. m. teal and r. w. howarth, "howarth, oil spill studies: a review of ecological effects," environmental management, vol. 8, pp. 2743, 1984. available at: https://doi.org/10.1007/bf01867871. [57] a. nelson-smith, "the problem of oil pollution of the sea," advances in marine biology, vol. 8, pp. 215-306, 1971. available at: https://doi.org/10.1016/s0065-2881(08)60493-9. [58] s. ghoreishi and r. haghighi, "chemical catalytic reaction and biological oxidation for treatment of non-biodegradable textile effluent," chemical engineering journal, vol. 95, pp. 163-169, 2003. available at: https://doi.org/10.1016/s1385-8947(03)00100-1. [59] s. dey and a. islam, "a review on textile wastewater characterization in bangladesh," resources and environment, vol. 5, pp. 15-44, 2015. [60] i. hasan, s. rajia, k. a. kabir, and g. a. latifa, "comparative study on the water quality parameters in two rural and urban rivers emphasizing on the pollution level," global journal of environmental research, vol. 3, pp. 218-222, 2009. [61] m. ahmed, m. haque, and t. haque, "physicochemical assessment of surface and groundwater resources of greater comilla region of bangladesh," international journal of chemical and environmental engineering, vol. 1, pp. 47-55, 2010. [62] g. munna, "a canadian water quality guideline-water quality index (ccme-wqi) based assessment study of water quality in surma river," journal of civil engineering and construction technology, vol. 4, pp. 81-89, 2013. [63] k. ahmed, m. das, m. m. islam, m. s. akter, s. islam, and m. a. al-mansur, "physico-chemical properties of tannery and textile effluents and surface water of river buriganga and karnatoli, bangladesh," world applied sciences journal, vol. 12, pp. 152-159, 2011. [64] d. kamal, a. khan, m. rahman, and f. ahamed, "study on the physico chemical properties of water of mouri river, khulna, bangladesh," pakistan journal of biological sciences, vol. 10, pp. 710-717, 2007. available at: https://doi.org/10.3923/pjbs.2007.710.717. [65] z. t. begum and d. khanam, "physicochemical aspects and phytoplankton of the river shitalakhya receiving pharmaceutical effluents," bangladesh journal of botany, vol. 38, pp. 77-85, 2009. available at: https://doi.org/10.3329/bjb.v38i1.5127. [66] m. r. islam, n. das, p. barua, m. b. hossain, s. venkatramanan, and s. chung, "environmental assessment of water and soil contamination in rajakhali canal of karnaphuli river (bangladesh) impacted by anthropogenic influences: a preliminary case study," applied water science, vol. 7, pp. 997-1010, 2017. available at: https://doi.org/10.1007/s13201-015-0310-2. asian review of environmental and earth sciences, 2019, 6(1): 47-69 66 © 2019 by the authors; licensee asian online journal publishing group [67] f. raihan and j. alam, "assessment of groundwater quality in sunamganj of bangladesh," journal of environmental health science & engineering, vol. 5, pp. 155-166, 2008. [68] m. ahmed, m. haque, a. ahsan, s. siraj, m. bhuiyan, s. bhattacharjee, and s. islam, "physicochemical assessment of surface and groundwater quality of the greater chittagong region of bangladesh," pakistan journal of analytical & environmental chemistry, vol. 11, pp. 1-11, 2010. available at: https://doi.org/10.6026/97320630011543. [69] j. islam, a. hakim, m. m. hanafi, a. s. juraimi, r. r. sarkar, a. hossain, i. chowdhury, j. ali, and a. kashem, "assessing groundwater stoichiometric composition and its suitability in northwestern bangladesh," ciência rural, vol. 44, pp. 1210-1218, 2014. available at: https://doi.org/10.1590/0103-8478cr20130712. [70] m. m. a. molla, n. saha, s. m. a. salam, and m. rakib-uz-zaman, "surface and groundwater quality assessment based on multivariate statistical techniques in the vicinity of mohanpur, bangladesh," international journal of environmental health engineering, vol. 4, pp. 1-9, 2015. available at: https://doi.org/10.4103/2277-9183.157717. [71] m. m. bahar and m. s. reza, "hydrochemical characteristics and quality assessment of shallow groundwater in a coastal area of southwest bangladesh," environmental earth sciences, vol. 61, pp. 1065-1073, 2010. available at: https://doi.org/10.1007/s12665009-0427-4. [72] b. simpi, s. hiremath, k. murthy, k. chandrashekarappa, a. patel, and e. puttiah, "analysis of water quality using physicochemical parameters hosahalli tank in shimoga district, karnataka, india," global journal of science frontier research, vol. 11, pp. 31-34, 2011. [73] h. b. n. hynes and h. hynes, the ecology of running waters vol. 555. liverpool: liverpool university press liverpool, 1970. [74] h. s. mandal, a. das, and a. k. nanda, "study of some physicochemical water quality parameters of karola river, west bengal-an attempt to estimate pollution status," international journal of environmental protection, vol. 2, pp. 16-22, 2012. [75] eqs (environmental quality standards for bangladesh), department of environment: government of the people’s republic of bangladesh, 1991. [76] r. trivedy and p. goel, chemical and biological methods for water pollution studies: environmental publications, 1984. [77] who world health organization, guidelines for dirnking water quality, 2nd ed. geneva, 1997. [78] m. sikder, m. yasuda, s. m. syawal, t. saito, s. tanaka, and m. kurasaki, "comparative assessment of water quality in the major rivers of dhaka and west java," international journal of environmental protection, vol. 2, pp. 8-13, 2012. [79] m. tabata, a. ghaffar, y. eto, j. nishimoto, and k. yamamoto, "distribution of heavy metals in interstitial waters and sediments at different sites in ariake bay, japan," water-journal of european water association, vol. 5, pp. 1-24, 2007. [80] r. srivastava, a. sinha, d. pande, k. singh, and h. chandra, "water quality of the river ganga at phaphamau (allahabad)—effect of mass bathing during mahakumbh," environmental toxicology and water quality: an international journal, vol. 11, pp. 1-5, 1996. available at: https://doi.org/10.1002/(sici)1098-2256(1996)11:1<1::aid-tox1>3.3.co;2-e. [81] r. patel, s. prasher, r. bonnell, and r. broughton, "development of comprehensive soil salinity index," journal of irrigation and drainage engineering, vol. 128, pp. 185-188, 2002. available at: https://doi.org/10.1061/(asce)0733-9437(2002)128:3(185. [82] k. bellingham, physicochemical parameters of natural waters: stevens water monitoring systems inc, 2012. [83] who, world health organization, guidelines for drinking water quality. geneva, switzerland, 1st ed., 1981. [84] neqs, "national environmental quality standards for municipal and liquid industrial effluents. pakistan," 2000. [85] n. s. rao, "seasonal variation of groundwater quality in a part of guntur district, andhra pradesh, india," environmental geology, vol. 49, pp. 413-429, 2006. [86] s. ramprasad, ecology and economics: an approach to sustainable development. india: oxford university press, 2001. [87] f. edition, "guidelines for drinking-water quality," who chronicle, vol. 38, pp. 104-108, 2011. [88] a. e. khan, a. ireson, s. kovats, s. k. mojumder, a. khusru, a. rahman, and p. vineis, "drinking water salinity and maternal health in coastal bangladesh: implications of climate change," environmental health perspectives, vol. 119, pp. 1328-1332, 2011. available at: https://doi.org/10.1289/ehp.1002804. [89] h. rashid, m. n. hasan, m. b. tanu, r. parveen, z. sukhan, m. s. rahman, and y. mahmud, "heavy metal pollution and chemical profile of khiru river, bangladesh," international journal of environment, vol. 2, pp. 57-63, 2012. [90] a. t. ahmed, s. mandal, d. chowdhury, a. r. tareq, and m. m. rahman, "bioaccumulation of some heavy metals in ayre fish (sperata aor hamilton, 1822), sediment and water of dhaleshwari river in dry season," bangladesh journal of zoology, vol. 40, pp. 147-153, 2012. available at: https://doi.org/10.3329/bjz.v40i1.12904. [91] m. mokaddes, b. nahar, and m. baten, "status of heavy metal contaminations of river water of dhaka metropolitan city," journal of environmental science and natural resources, vol. 5, pp. 349-353, 2013. available at: https://doi.org/10.3329/jesnr.v5i2.14842. [92] m. z. islam, a. noori, r. islam, m. a. azim, and s. b. quraishi, "assessment of the contamination of trace metal in balu river water, bangladesh," journal of environmental chemistry and ecotoxicology, vol. 4, pp. 242-249, 2012. [93] m. s. islam, m. k. ahmed, m. raknuzzaman, m. habibullah-al-mamun, and m. k. islam, "heavy metal pollution in surface water and sediment: a preliminary assessment of an urban river in a developing country," ecological indicators, vol. 48, pp. 282-291, 2015. available at: https://doi.org/10.1016/j.ecolind.2014.08.016. [94] h. zakir, "heavy metals and major ionic pollution assessment in waters of midstream of the river karatoa in bangladesh," journal of environmental science and natural resources, vol. 5, pp. 149-160, 2013. [95] m. k. ahmed, s. ahamed, s. rahman, m. r. haque, and m. m. islam, "heavy metals concentration in water, sediments and their bioaccumulations in some freshwater fishes and mussel in dhaleshwari river, bangladesh," terrestrial and aquatic environmental toxicology, vol. 3, pp. 33-41, 2009. [96] m. ahmad, s. islam, m. rahman, m. haque, and m. islam, "heavy metals in water, sediment and some fishes of buriganga river, bangladesh," international journal of environmental research, vol. 4, pp. 321-332, 2010. [97] m. s. akter, t. sikder, and a. ullah, "water quality assessment of an industrial zone polluted aquatic body in dhaka, bangladesh," american journal of environmental protection, vol. 3, pp. 232-237, 2014. available at: https://doi.org/10.11648/j.ajep.20140305.14. [98] m. a. h. bhuiyan, n. i. suruvi, s. b. dampare, m. islam, s. b. quraishi, s. ganyaglo, and s. suzuki, "investigation of the possible sources of heavy metal contamination in lagoon and canal water in the tannery industrial area in dhaka, bangladesh," environmental monitoring and assessment, vol. 175, pp. 633-649, 2011. available at: https://doi.org/10.1007/s10661-010-1557-6. [99] a. hussam, m. habibuddowla, m. alauddin, z. hossain, a. munir, and a. khan, "chemical fate of arsenic and other metals in groundwater of bangladesh: experimental measurement and chemical equilibrium model," journal of environmental science and health, part a, vol. 38, pp. 71-86, 2003. available at: https://doi.org/10.1081/ese-120016882. [100] m. r. islam, r. salminen, and p. lahermo, "arsenic and other toxic elemental contamination of groundwater, surface water and soil in bangladesh and its possible effects on human health," environmental geochemistry and health, vol. 22, pp. 33-53, 2000. [101] a. zahid, k.-d. balke, m. q. hassan, and m. flegr, "evaluation of aquifer environment under hazaribagh leather processing zone of dhaka city," environmental geology, vol. 50, pp. 495-504, 2006. [102] a. ilyas and t. sarwar, "study of trace elements in drinking water in the vicinity of palosi drain, peshawar," pakistan journal of biological sciences, vol. 6, pp. 86-91, 2003. available at: https://doi.org/10.3923/pjbs.2003.86.91. [103] u. kumar and m. bandyopadhyay, "sorption of cadmium from aqueous solution using pretreated rice husk," bioresource technology, vol. 97, pp. 104-109, 2006. available at: https://doi.org/10.1016/j.biortech.2005.02.027. [104] g. bryan and w. langston, "bioavailability, accumulation and effects of heavy metals in sediments with special reference to united kingdom estuaries: a review," environmental pollution, vol. 76, pp. 89-131, 1992. available at: https://doi.org/10.1016/02697491(92)90099-v. [105] l. g. du, j. rinklebe, b. vandecasteele, e. meers, and f. m. tack, "trace metal behaviour in estuarine and riverine floodplain soils and sediments: a review," science of the total environment, vol. 407, pp. 3972-3985, 2009. available at: https://doi.org/10.1016/j.scitotenv.2008.07.025. [106] a. m. el nemr, a. el sikaily, and a. khaled, "total and leachable heavy metals in muddy and sandy sediments of egyptian coast along mediterranean sea," environmental monitoring and assessment, vol. 129, pp. 151-168, 2007. available at: https://doi.org/10.1007/s10661-006-9349-8. asian review of environmental and earth sciences, 2019, 6(1): 47-69 67 © 2019 by the authors; licensee asian online journal publishing group [107] j. gawdzik and b. gawdzik, "mobility of heavy metals in municipal sewage sludge from different throughput sewage treatment plants," polish journal of environmental studies, vol. 21, pp. 1603-1611, 2012. [108] a. farkas, c. erratico, and l. vigano, "assessment of the environmental significance of heavy metal pollution in surficial sediments of the river po," chemosphere, vol. 68, pp. 761-768, 2007. available at: https://doi.org/10.1016/j.chemosphere.2006.12.099. [109] j. morillo, j. usero, and i. gracia, "heavy metal distribution in marine sediments from the southwest coast of spain," chemosphere, vol. 55, pp. 431-442, 2004. available at: https://doi.org/10.1016/j.chemosphere.2003.10.047. [110] e. j. calabrese, a. canada, and c. sacco, "trace elements and public health," annual review of public health, vol. 6, pp. 131-146, 1985. [111] m. khan and s. biswas, "investigation of heavy metal pollution in peripheral river water around dhaka city," pensee journal, vol. 75, pp. 421-435, 2013. [112] p. saranraj and d. sujitha, "microbial bioremediation of chromium in tannery effluent: a review," international journal of microbiological research, vol. 4, pp. 305-306, 2013. [113] a. kabata-pendias, trace elements in soils and plants. usa: crc press, 2010. [114] r. sharma, m. agrawal, and f. marshall, "heavy metal contamination in vegetables grown in wastewater irrigated areas of varanasi, india," bulletin of environmental contamination and toxicology, vol. 77, pp. 312-318, 2006. [115] e. el-ebiary, o. wahbi, and z. el-greisy, "influence of dietary cadmium on sexual maturity and reproduction of red tilapia," the egyptian journal of aquatic research, vol. 39, pp. 313-317, 2013. [116] j. nyamangara, c. bangira, t. taruvinga, c. masona, a. nyemba, and d. ndlovu, "effects of sewage and industrial effluent on the concentration of zn, cu, pb and cd in water and sediments along waterfalls stream and lower mukuvisi river in harare, zimbabwe," physics and chemistry of the earth, parts a/b/c, vol. 33, pp. 708-713, 2008. [117] o. fatoki and r. awofolu, "levels of cd, hg and zn in some surface waters from the eastern cape province, south africa," water sa, vol. 29, pp. 375-380, 2003. [118] s. h. rahman, d. khanam, t. m. adyel, m. s. islam, m. a. ahsan, and m. a. akbor, "assessment of heavy metal contamination of agricultural soil around dhaka export processing zone (depz), bangladesh: implication of seasonal variation and indices," applied sciences, vol. 2, pp. 584-601, 2012. available at: https://doi.org/10.3390/app2030584. [119] who, guidelines for drinking-water quality, 3rd ed. vol. 1. geneva: world health organization, 2004. [120] e. caussy and w. h. organization, a field guide for detection, management and surveillance of arsenicosis cases. new delhi: world health organization, 2005. [121] c. o. abernathy, d. j. thomas, and r. l. calderon, "health effects and risk assessment of arsenic," the journal of nutrition, vol. 133, pp. 1536s-1538s, 2003. [122] r. j. p. williams and j. f. da silva, new trends in bio-inorganic chemistry. new york: academic press, 1978. [123] h. sanstead, interaction of cadmium and lead with essential minerals. in; gf nordberg (ed.), effects and dose-response relationships of toxic metals. amsterdam: elsevier, 1976. [124] m. rao, r. gopalkrishnan, and b. venkatesh, "medical geology–an emerging field in environmental science. in national symposium on role of earth sciences," presented at the national symposium on rrole of earth sciences, 2001. [125] j. y. z. m. z. y. x. g. r. qiu, "heavy metal (pb, zn) uptake and chemical changes in rhizosphere soils of four wetland plants with different radial oxygen loss," journal of environmental sciences, vol. 22, pp. 696-702, 2010. [126] p. sivaperumal, t. sankar, and p. v. nair, "heavy metal concentrations in fish, shellfish and fish products from internal markets of india vis-a-vis international standards," food chemistry, vol. 102, pp. 612-620, 2007. [127] j. gorell, c. johnson, b. rybicki, e. peterson, g. kortsha, g. brown, and r. richardson, "occupational exposures to metals as risk factors for parkinson's disease," neurology, vol. 48, pp. 650-658, 1997. [128] a. azizullah, m. n. khattak, p. richter, and d.-p. häder, "water pollution in pakistan and its impact on public health—a review," environment international, vol. 37, pp. 479-497, 2011. [129] l. beckman, g. van landeghem, c. sikstrom, a. wahlin, b. markevarn, g. hallmans, p. lenner, l. athlin, r. stenling, and l. beckman, "interaction between haemochromatosis and transferrin receptor genes in different neoplastic disorders," carcinogenesis, vol. 20, pp. 1231-1233, 1999. [130] c. ellervik, t. mandrup-poulsen, b. g. nordestgaard, l. larsen, m. appleyard, m. frandsen, p. petersen, p. schlichting, t. saermark, and a. tybjaerg-hansen, "prevalence of hereditary haemochromatosis in late-onset type 1 diabetes mellitus: a retrospective study," the lancet, vol. 358, pp. 1405-1409, 2001. [131] q. yang, s. m. mcdonnell, m. j. khoury, j. cono, and r. g. parrish, "hemochromatosis-associated mortality in the united states from 1979 to 1992: an analysis of multiple-cause mortality data," annals of internal medicine, vol. 129, pp. 946-953, 1998. [132] r. lauwerys and d. lison, "health risks associated with cobalt exposure—an overview," science of the total environment, vol. 150, pp. 1-6, 1994. [133] m. a. h. bhuiyan, n. i. suruvi, s. b. dampare, m. islam, s. b. quraishi, s. ganyaglo, and s. suzuki, "investigation of the possible sources of heavy metal contamination in lagoon and canal water in the tannery industrial area in dhaka, bangladesh," environmental monitoring and assessment, vol. 175, pp. 633-649, 2011. available at: https://doi.org/10.1007/s10661-010-1557-6. [134] a. raviraja, v. babu, g. narayanamurthy, a. r. bijoor, g. menezes, and t. venkatesh, "lead toxicity in a family as a result of occupational exposure," archives of occupational hygiene and toxicology, vol. 59, pp. 127-133, 2008. [135] g. yaylalı-abanuz, "heavy metal contamination of surface soil around gebze industrial area, turkey," microchemical journal, vol. 99, pp. 82-92, 2011. [136] m. a. arain, z. haque, n. badar, and n. mughal, "drinking water contamination by chromium and lead in industrial lands of karachi," the journal of the pakistan medical association, vol. 59, p. 270, 2009. [137] h. mukai, a. tanaka, t. fujii, and m. nakao, "lead isotope ratios of airborne particulate matter as tracers of long-range transport of air pollutants around japan," journal of geophysical research: atmospheres, vol. 99, pp. 3717-3726, 1994. [138] n. shikazono, k. tatewaki, k. mohiuddin, t. nakano, and h. zakir, "sources, spatial variation, and speciation of heavy metals in sediments of the tamagawa river in central japan," environmental geochemistry and health, vol. 34, pp. 13-26, 2012. [139] t. venkatesh, "the effects of environmental lead on human health-a challenging scenario," health focus, vol. 2, pp. 8-16, 2004. [140] m. l. riess and j. k. halm, "lead poisoning in an adult: lead mobilization by pregnancy?," journal of general internal medicine, vol. 22, pp. 1212-1215, 2007. [141] m. homady, h. hussein, a. jiries, a. mahasneh, f. al-nasir, and k. khleifat, "survey of some heavy metals in sediments from vehicular service stations in jordan and their effects on social aggression in prepubertal male mice," environmental research, vol. 89, pp. 43-49, 2002. [142] a. r. oller, m. costa, and g. oberdörster, "carcinogenicity assessment of selected nickel compounds," toxicology and applied pharmacology, vol. 143, pp. 152-166, 1997. [143] d. mcgregor, r. baan, c. partensky, j. rice, and j. wilbourn, "evaluation of the carcinogenic risks to humans associated with surgical implants and other foreign bodies—a report of an iarc monographs programme meeting," european journal of cancer, vol. 36, pp. 307-313, 2000. [144] national academy of sciences nas. washington, dc: national academy press, 1973. [145] j. crossgrove and w. zheng, "manganese toxicity upon overexposure," nmr in biomedicine: an international journal devoted to the development and application of magnetic resonance in vivo, vol. 17, pp. 544-553, 2004. available at: https://doi.org/10.1002/nbm.931. [146] m. moniruzzaman, s. f. elahi, and m. a. a. jahangir, "study on temporal variation of physico-chemical parameters of buriganga river water through gis (geographical information system) technology," bangladesh journal of scientific and industrial research, vol. 44, pp. 327-334, 2009. available at: https://doi.org/10.3329/bjsir.v44i3.4406. asian review of environmental and earth sciences, 2019, 6(1): 47-69 68 © 2019 by the authors; licensee asian online journal publishing group [147] j. b. islam, s. akter, a. c. bhowmick, m. n. uddin, and m. sarkar, "hydro-environmental pollution of turag river in bangladesh," bangladesh journal of scientific industrial research, vol. 53, pp. 161-168, 2018. available at: https://doi.org/10.3329/bjsir.v53i3.38261. [148] r. alam, j. alam, m. hasan, s. das, k. rahman, and b. banik, "study of water quality of sylhet city and its restaurants: health associated risk assessment," journal of environmental health science & engineering, vol. 3, pp. 9-18, 2006. [149] n. raza, s. b. niazi, m. sajid, f. iqbal, and m. ali, "studies on relationship between season and inorganic elements of kallar kahar lake (chakwal), pakistan," journal of research (science), bahauddin zakariya university, vol. 18, pp. 61-68, 2007. [150] r. p. heaney, j. gallagher, c. johnston, r. neer, a. m. parfitt, and g. d. whedon, "calcium nutrition and bone health in the elderly," the american journal of clinical nutrition, vol. 36, pp. 986-1013, 1982. [151] a. ghosh, k. mukherjee, s. k. ghosh, and b. saha, "sources and toxicity of fluoride in the environment," research on chemical intermediates, vol. 39, pp. 2881-2915, 2013. available at: https://doi.org/10.1007/s11164-012-0841-1. [152] cdcp, "center for disease control and prevention, achievements in public health, 1900-1999: fluoridation of drinking water to prevent dental caries," morbidity and mortality weekly report, vol. 48, pp. 933-940, 1999. [153] p. j. weyer, j. r. cerhan, b. c. kross, g. r. hallberg, j. kantamneni, g. breuer, m. p. jones, w. zheng, and c. f. lynch, "municipal drinking water nitrate level and cancer risk in older women: the iowa women’s health study," epidemiology, vol. 12, pp. 327-338, 2001. available at: https://doi.org/10.1097/00001648-200105000-00013. [154] k. f. murray and d. l. christie, "dietary protein intolerance in infants with transient methemoglobinemia and diarrhea," the journal of pediatrics, vol. 122, pp. 90-92, 1993. available at: https://doi.org/10.1016/s0022-3476(05)83495-x. [155] nas, national academy of sciences—national research council academy of life sciences. the health effects of nitrate, nitrite, and n-nitroso compounds. washington dc: national academy of sciences press, 1981. [156] m. khatun, s. hoque, m. islam, j. khatoon, and m. hossain, "presence of organophosphorus pesticide residues in surface water in dhaka city," journal of subtropical agricultural research and development, vol. 6, pp. 506-511, 2008. [157] a. chowdhury, s. a. jahan, m. n. islam, m. moniruzzaman, m. k. alam, m. a. zaman, n. karim, and s. gan, "occurrence of organophosphorus and carbamate pesticide residues in surface water samples from the rangpur district of bangladesh," bulletin of environmental contamination and toxicology, vol. 89, pp. 202-207, 2012. available at: https://doi.org/10.1007/s00128-012-0641-8. [158] m. chowdhury, a. zaman, s. banik, b. uddin, m. moniruzzaman, n. karim, and s. gan, "organophosphorus and carbamate pesticide residues detected in water samples collected from paddy and vegetable fields of the savar and dhamrai upazilas in bangladesh," international journal of environmental research and public health, vol. 9, pp. 3318-3329, 2012. [159] a. z. chowdhury, m. islam, m. moniruzzaman, s. h. gan, and m. k. alam, "organochlorine insecticide residues are found in surface, irrigated water samples from several districts in bangladesh," bulletin of environmental contamination and toxicology, vol. 90, pp. 149-154, 2013. [160] m. a. z. chowdhury, m. a. uddin, m. t. sultan, m. hasanuzzaman, m. a. hoque, and m. zaman, "pesticide residues in water samples of some paddy fields in narayangonj," chittagong university journal of biological sciences, vol. 5, pp. 155-157, 2013. [161] k. a. sumon, a. rico, m. m. ter horst, p. van den brink, m. m. haque, and h. rashid, "risk assessment of pesticides used in rice-prawn concurrent systems in bangladesh," science of the total environment, vol. 568, pp. 498-506, 2016. [162] nhmrc (national health and medical research council), "australian drinking water guidelines. agricultural and resource management council of australia and new zealand. commonwealth of australia," 1996. [163] m. hossain, m. a. z. chowdhury, m. k. pramanik, m. rahman, a. fakhruddin, and m. k. alam, "determination of selected pesticides in water samples adjacent to agricultural fields and removal of organophosphorus insecticide chlorpyrifos using soil bacterial isolates," applied water science, vol. 5, pp. 171-179, 2015. [164] c. turgut, l. atatanir, and t. j. cutright, "evaluation of pesticide contamination in dilek national park, turkey," environmental monitoring and assessment, vol. 170, pp. 671-679, 2010. [165] gob-unicef, "government of bangladesh-united nations international children's emergency fund rural water supply and sanitation program. 1992-1999, dhaka," 1991. [166] g. medema, p. payment, a. dufour, w. robertson, m. waite, p. hunter, r. kirby, and y. andersson, "safe drinking water: an ongoing challenge," assessing microbial safety of drinking water, vol. 11, 2003. [167] m. m. kamal, a. malmgren-hansen, and a. badruzzaman, "assessment of pollution of the river buriganga, bangladesh, using a water quality model," water science and technology, vol. 40, pp. 129-136, 1999. available at: https://doi.org/10.2166/wst.1999.0104. [168] m. islam, h. sakakibara, m. karim, m. sekine, and z. mahmud, "bacteriological assessment of drinking water supply options in coastal areas of bangladesh," journal of water and health, vol. 9, pp. 415-428, 2011. available at: https://doi.org/10.2166/wh.2011.114. [169] m. m. hasan, m. k. ahmed, f. hafiz, a. m. i. hussain, s. parveen, and s. r. tinni, "load of heteload of heterotrophicrotrophic and nitrifying bacteria in the sewage lagoon and the receiving river buriganga," bangladesh journal of microbiology, vol. 23, pp. 9397, 2006. available at: https://doi.org/10.3329/bjm.v23i2.869. [170] m. acharjee, f. rahman, f. jahan, and r. noor, "bacterial proliferation in municipal water supplied in mirpur locality of dhaka city, bangladesh," clean–soil, air, water, vol. 42, pp. 434-441, 2014. available at: https://doi.org/10.1002/clen.201200618. [171] s. c. mandal, m. hasan, m. s. rahman, m. manik, z. h. mahmud, and m. s. islam, "coliform bacteria in nile tilapia, oreochromis niloticus of shrimp-gher, pond and fish market," world journal of fish and marine sciences, vol. 1, pp. 160-166, 2009. [172] m. islam, m. alam, s. khan, and a. huq, "faecal pollution of freshwater environments in bangladesh," international journal of environmental studies, vol. 46, pp. 161-165, 1994. available at: https://doi.org/10.1080/00207239408710921. [173] a. huq, k. sac, a. nizam, i. m. longini, g. b. nair, a. ali, j. g. morris, j. g. khan, a. k. siddique, and m. yunus, "critical factors influencing the occurrence of vibrio cholerae in the environment of bangladesh," applied and environmental microbiology, vol. 71, pp. 4645-4654,, 2005. [174] m. rasul and m. jahan, "quality of ground and surface water of rajshahi city area for sustainable drinking water source," journal of scientific research, vol. 2, pp. 579-586, 2010. available at: https://doi.org/10.3329/jsr.v2i3.4093. [175] a. van geen, k. m. ahmed, y. akita, m. j. alam, p. j. culligan, m. emch, v. escamilla, j. feighery, a. s. ferguson, p. knappett, a. c. layton, b. j. mailloux, l. d. mckay, j. l. mey, m. l. serre, p. k. streatfield, j. wu, and m. yunus, "fecal contamination of shallow tubewells in bangladesh inversely related to arsenic," environmental science technology, vol. 45, pp. 1199-1205, 2011. available at: https://doi.org/10.1021/es103192b. [176] r. datta, m. b. hossain, m. aktaruzzaman, and a. fakhruddin, "antimicrobial resistance of pathogenic bacteria isolated from tube well water of costal area of sitakunda, chittagong, bangladesh," open journal of water pollution and treatment, vol. 1, pp. 1-10, 2014. [177] j. p. cabral, "water microbiology. bacterial pathogens and water," international journal of environmental research and public health, vol. 7, pp. 3657-3703, 2010. [178] a. k. chopra and c. w. houston, "enterotoxins in aeromonas-associated gastroenteritis," microbes and infection, vol. 1, pp. 11291137, 1999. [179] n. amanidaz, a. zafarzadeh, and a. h. mahvi, "the interaction between heterotrophic bacteria and coliform, fecal coliform, fecal streptococci bacteria in the water supply networks," iranian journal of public health, vol. 44, pp. 1685-1692, 2015. [180] h. muckter, antibiotics residues in drinking water. 47. garmisch-patenkirchen: arbeitstagung des arbeitsgebiets lebensmittelhygiene, 2006. [181] a. hossain, s. nakamichi, m. h. mamun, k. tani, s. masunaga, and h. matsuda, "occurrence and ecological risk of pharmaceuticals in river surface water of bangladesh," environmental research, vol. 165, pp. 258-266, 2018. available at: https://doi.org/10.1016/j.envres.2018.04.030. [182] m. huerta-fontela, m. t. galceran, and f. ventura, "occurrence and removal of pharmaceuticals and hormones through drinking water treatment," water research, vol. 45, pp. 1432-1442, 2011. available at: https://doi.org/10.1016/j.watres.2010.10.036. asian review of environmental and earth sciences, 2019, 6(1): 47-69 69 © 2019 by the authors; licensee asian online journal publishing group [183] a. bahlmann, w. brack, r. j. schneider, and m. krauss, "carbamazepine and its metabolites in wastewater: analytical pitfalls and occurrence in germany and portugal," water research, vol. 57, pp. 104-114, 2014. available at: https://doi.org/10.1016/j.watres.2014.03.022. [184] a. hossain, s. nakamichi, m. h. mamun, k. tani, s. masunaga, and h. matsuda, "occurrence, distribution, ecological and resistance risks of antibiotics in surface water of finfish and shellfish aquaculture in bangladesh," chemosphere, vol. 188, pp. 329-336, 2017. available at: https://doi.org/10.1016/j.chemosphere.2017.08.152. [185] a. hossain, s. nakamichi, m. habibullah-al-mamun, k. tani, s. masunaga, and h. matsuda, "occurrence and ecological risk of pharmaceuticals in river surface water of bangladesh," environmental research, vol. 165, pp. 258-266, 2018. [186] m. patel, r. kumar, k. kishor, t. mlsna, c. u. pittman jr, and d. mohan, "pharmaceuticals of emerging concern in aquatic systems: chemistry, occurrence, effects, and removal methods," chemical reviews, vol. 119, pp. 3510-3673, 2019. [187] pubchem, "national institutes of health (nih): united states of america," 2004. [188] m. wagil, j. maszkowska, a. białk-bielińska, m. caban, p. stepnowski, and j. kumirska, "determination of metronidazole residues in water, sediment and fish tissue samples," chemosphere, vol. 119, pp. s28-s34, 2015. available at: https://doi.org/10.1016/j.chemosphere.2013.12.061. [189] d. w. kolpin, e. t. furlong, m. t. meyer, e. m. thurman, s. d. zaugg, l. b. barber, and h. t. buxton, "pharmaceuticals, hormones, and other organic wastewater contaminants in us streams, 1999− 2000: a national reconnaissance," environmental science technology, vol. 36, pp. 1202-1211, 2002. available at: https://doi.org/10.1021/es011055j. [190] q. zheng, r. zhang, y. wang, x. pan, j. tang, and g. zhang, "occurrence and distribution of antibiotics in the beibu gulf, china: impacts of river discharge and aquaculture activities," marine environmental research, vol. 78, pp. 26-33, 2012. available at: https://doi.org/10.1016/j.marenvres.2012.03.007. [191] r. moreno-gonzález, s. rodriguez, b. huerta, d. barcelo, and v. m. leon, "do pharmaceuticals bioaccumulate in marine molluscs and fish from a coastal lagoon?," environmental research, vol. 146, pp. 282-298, 2016. available at: https://doi.org/10.1016/j.envres.2016.01.001. [192] a. sangion and p. gramatica, "hazard of pharmaceuticals for aquatic environment: prioritization by structural approaches and prediction of ecotoxicity," environment international, vol. 95, pp. 131-143, 2016. available at: https://doi.org/10.1016/j.envint.2016.08.008. [193] k. kümmerer, "antibiotics in the aquatic environment–a review–part i," chemosphere, vol. 75, pp. 417-434, 2009. available at: https://doi.org/10.1016/j.chemosphere.2008.11.086. [194] a. a. sapkota, r. sapkota, m. kucharski, j. burke, s. mckenzie, p. walker, and r. lawrence, "aquaculture practices and potential human health risks: current knowledge and future priorities," environment international, vol. 34, pp. 1215-1226, 2008. available at: https://doi.org/10.1016/j.envint.2008.04.009. [195] s. shankar and u. shanker, "arsenic contamination of groundwater: a review of sources, prevalence, health risks, and strategies for mitigation," the scientific world journal, vol. 2014, pp. 1-18, 2014. available at: http://dx.doi.org/10.1155/2014/304524. [196] n. khatri and s. tyagi, "influences of natural and anthropogenic factors on surface and groundwater quality in rural and urban areas," frontiers in life science, vol. 8, pp. 23-39, 2015. [197] g. r. watzlaf, k. t. schroeder, r. l. kleinmann, c. l. kairies, and r. w. nairn, "the passive treatment of coal mine drainage," united states department of energy national energy technology laboratory internal publication, pp. 1-72, 2004. [198] j. c. davis, statistics and data analysis in geology. new york: wiley 1986. [199] m. m. ali, m. l. ali, m. s. islam, and m. z. rahman, "preliminary assessment of heavy metals in water and sediment of karnaphuli river, bangladesh," environmental nanotechnology, monitoring & management, vol. 5, pp. 27-35, 2016. available at: 10.1016/j.enmm.2016.01.002. [200] a. f. lezzoni and m. p. pritts, "applications of principal component analysis to horticultural research," hortscience, vol. 26, pp. 334-338, 1991. [201] v. p. marisol, "enrique barroso and luis debaâ and, assessment of seasonal and pollution effects on the quality of river water by exploratory data analysis," water research, vol. 32, pp. 3581-3592, 1998. [202] a. danielsson, i. cato, r. carman, and l. rahm, "spatial clustering of metals in the sediments of the skagerrak/kattegat," applied geochemistry, vol. 14, pp. 689-706, 1999. [203] j. bartram and r. ballance, water quality monitoring a practical guide to the design and implementation of freshwater quality studies and monitoring programmes. new york: crc press, 1996. [204] who (world health organization), guidelines for drinking-water quality, surveillance and control of community supplies 2nd ed. vol. 3, 1997. [205] m. r. islam, n. g. das, p. barua, m. b. hossain, s. venkatramanan, and s. y. chung, "environmental assessment of water and soil contamination in rajakhali canal of karnaphuli river (bangladesh) impacted by anthropogenic influences: a preliminary case study," applied water science, vol. 7, pp. 997-1010, 2015. available at: 10.1007/s13201-015-0310-2. [206] usgs, "u. s. geology survey national field manual for the collection of water-quality data (twri book 9) chapter a4," collection of water samples (version 2.0, 9/2006), p. 33, 2006. [207] m. m. hossan, "evolution of environmental policies in bangladesh (1972-2010)," journal of the asiatic society of bangladesh, vol. 59, pp. 39-63, 2014. [208] beca, "bangladesh environment conservation act 1995," people's republic of bangladesh, pp. 153-164, 1995. [209] eqs, "environmental quality standard," bangladesh gazette, people's republic of bangladesh, pp. 179-227, 1997. [210] s. tanzeema and i. faisal, "sharing the ganges: a critical analysis of the water sharing treaties," water policy, vol. 3, pp. 13-28, 2001. [211] s. prasai and m. surie, political economy analysis of the teesta river basin vol. 37. new delhi: the asia foundation, 2013. [212] m. f. islam and y. higano, "attainment of economic benefit through optimal sharing of international river water: a case study of the teesta river," indian journal of regional science, vol. 34, pp. 1-10, 2002. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://dx.doi.org/10.1155/2014/304524 1 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 1-8, 2019 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.1.8 © 2019 by the authors; licensee asian online journal publishing group water temperature prediction models in northern coastal area, vietnam nguyen xuan trinh1 tu quang trinh2 thanh phuong phan3 tung nguyen thanh4 bach nguyen thanh5 ( corresponding author) 1,2,3,4,5vietnam institute of fisheries economics and planning, vietnam abstract this paper presents the results of regression models (linear, nonlinear and stochastic regression) and artificial neural network models (ann) using observed data of daily maximum air and water temperature at bai chay station in the coastal areas of northern delta, vietnam. the accuracy of the models was evaluated and compared by r, rmse, rmse% and e indicators. the ann model was highlight results with the rmse = 1.24; r = 0.98; e = 0.9; rmse% = 4. the results of the study also show that daily water temperature is affected by daily maximum and average air temperature of previous 1 and 2 days. the main contribution of this study is to identify the appropriate models and time lag factors for water temperature prediction from the air temperature applied to neighboring meteorological stations without water temperature monitoring data. the results of the study could be used as a basis for determining the spatial distribution of water temperature risk to aquaculture in the coastal areas of northern delta, vietnam. keywords: mathematical methods, environmental issues, climate, water, forecasting models, model evaluation citation | nguyen xuan trinh; tu quang trinh; thanh phuong phan; tung nguyen thanh; bach nguyen thanh (2019). water temperature prediction models in northern coastal area, vietnam. asian review of environmental and earth sciences, 6(1): 1-8. history: received: 12 october 2018 revised: 15 november 2018 accepted: 17 december 2018 published: 25 january 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: the authors gratefully acknowledge all the support and assistance of the program management board. the authors also wish to thank the referee, the editor, and sara lim for helpful comments and constructive criticism. funding: this research has been funded by the government of vietnam under the program of scientific and technological research for environmental protection and disaster prevention (code kc08/16-20). competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 2 2. data and methodology ...................................................................................................................................................................... 2 3. results and discussion ...................................................................................................................................................................... 4 4. conclusions .......................................................................................................................................................................................... 7 references ................................................................................................................................................................................................. 8 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.1.8&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 http://asianonlinejournals.com/index.php/arees/article/view/709 https://orcid.org/0000-0002-1762-9927 https://orcid.org/0000-0002-9941-104x https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0001-9945-5766 https://orcid.org/0000-0002-8614-7833 asian review of environmental and earth sciences, 2019, 6(1): 1-8 2 © 2019 by the authors; licensee asian online journal publishing group 1. introduction water temperature plays an important role in aquatic life, including aquaculture species [1, 2]. the water temperature affects other environmental parameters such as do, bod, algae growth, etc., and gets vulnerable to pathogenic bacteria. there are many factors affecting water temperature such as atmospheric conditions, topography and water flow [3]. among atmospheric factors (solar radiation, air temperature, wind speed, humidity etc.), air temperature is the most factor affecting the variation in surface water temperature [4] that lead to series of water condition change. in the northern coastal region of vietnam, beside natural disasters which directly affect fisheries such as storms, floods .etc. every year, the air temperature in summer can reach 39-400c with hot temperature in long duration, which makes the water temperature too high for the tolerance of aquatic species. on the other hand, when the water temperature rises, aquatic species tend to be active in water of deeper level, leading to an increase in oxygen demand [4] increasing the risk for intensive aquaculture ponds, so temperature is a particularly important factor threatening the stable development of aquaculture sector. therefore, when studying disaster risks for aquaculture, it is indispensible to consider the risks of maximum daily water temperature to determine the viability of aquatic species [5]. however, water temperature prediction is still a complexity [4] because water temperature depends on many factors. there are number of different application for water temperature predition model loubna, et al. [6]. caissie [3] divided into 3 main categories: regression, stochastic, and deterministic models. otherwise, caissie [3] and zhu, et al. [2] gave two categories deterministic and statistical models that they have advantages and drawback. the deterministic model applies simulations of water temperature using an approach that relates to the total amount of solar energy reaching the earth and the interrelated factors for determining water temperature (eg sinokrot and stefan [7]; webb and nobilis [8]). this approach is often impractical, complex and time-consuming in collecting and processing input data of many of the explanatory variables which are often difficult to collect such as solar radiation, wind, atmospheric energy [4, 6]. statistical models could be classified in two categories including parametric and non-parametric models. parametric models can also be decomposed into regression and stochatic models. the regression model simulating water temperature based on air temperature is commonly used in many studies due to the simplicity of the collected data and applied for weekly, monthly and annual time steps of data. the regression models including: single and multi-variabe linear regression or nonlinear regression. simple linear regression using air temperature (monthly or weekly data) is an explanatory variables to determine water temperature [9]. the nonlinear regression model proposed by mohseni, et al. [10] provided the base to many successful studies [11, 12]. however, regression simulation (linear or nonlinear) is less suitable to apply for shorter time steps such as daily data (due to autocorrelation in time series of water temperature) [6]. the stochastic model [13, 14] was developed from the regression model, proposed by kothandaraman [15] based on statistics of continuous time series of air temperature and water temperature to act as a basis for defining relationships through parameters. the stochastic model is generally applied to relatively short time data (hourly or daily data) and takes into account the time lag of the relevant factors. none-parametric models (k-nearest neighbour, artificial neural network model-ann, etc.) use the structure of availble data [6]. artificial neural network model (ann) has recently been developed with 3 basic layers of multi-layer backpropagation network model [2, 4]: the input layer, one or more hidden layers, and the output layer. the model always uses input data divided into two categories, namely training and testing data set. application of ann method has been successfully proved by some studies for water temperature predition (ex: anamarija [4]; marijana, et al. [16]; sahoo, et al. [17]; zhu, et al. [2]; deweber and wagner [18]). however, the comparison bettween models showed, in some cases ann models provided better results, while in other case, some regression models provide higher accuracy of results [2]. their resluts may depend on data quality and study areas, variables of time lags of the daily mean air temperature in multilayer perception ann models. therefore,the purpose of this study is to collect the appropriate model of water temperature prediction from air temperature data applying for the meteorological stations without observed water temperature and serving for determining the risk thresholds to aquaculture northern coastal areas vietnam. 2. data and methodology 2.1. data data of bai chay station, quang ninh province was used to evaluate the accuracy of the models. 10-years data (2008-2017) of daily air temperature and water temperature including maximum air temperature(ta_max); maximum water temperature(tw-max); average air temperature(ta_tb); average water temperature(tw_tb) of bai chay station is collected. figure-1. variation of water and air temperature source: data collected from bai chay station (e.g. of year 2008) asian review of environmental and earth sciences, 2019, 6(1): 1-8 3 © 2019 by the authors; licensee asian online journal publishing group figure 1 shows the correlation between the maximum water and the air temperature at bai chay station with the data 2008, points out that the water temperature always changes linearly depending on the maximum and average air temperature. during the year, the maximum water temperature is always lower than the maximum, but higher than the average air temperature. in some case, when fluctuation of day and night temperature suddenly change,the maximum water temperature may be higher than that ones of air temperature (in summer). thus, the maximum water temperature in a period of time always changes slowly and is not synchronized with the maximum air temperature and it creates a delay time between ta_max and tw-max 2.2. methodology a. simple linear regression model a simple linear regression model used a linear function with a single explanatory variable. the regression model simulates the variation of water temperature determined by the correlation with air temperature. simple linear regression equation: (1) tw(t): water temperature in time t ta(t): air temperature in time t; a0, a1 is the coefficient of the regression equation ε(t): error [6] b. nonlinear regression model most common nonlinear regression methods involve air and water temperatures [6] with 5 parameters.. (2) where tw: daily maximum water temperature predition ta: air temperature measured by day t , , β: the coefficient of the model, calculated by using the nonlinear regression model under the condition of minimum sum of squared difference (ssd). c. stochastic model stochastic model proposed by kothandaraman [15] and cluis [19]. in the model, water temperature tw is simulated by 2 basic components: (i) air temperature in long periods of time and water temperature in short time period. (3) (4) sin () function in equation (4) shows the trend of variation of water temperature by season or year cycle. ta(t): seasonal air temperature; a,b, t0: the correlation coefficient of the model which can be identified by nonlinear regression model. rw(t): water temperature over short period of time the stochastic model is used based on the development of a model proposed by kothandaraman [15] that determines the time lag between water temperature and air temperature (5) where: β1, β2 and β3 are the correlation coefficients of the model, calculated by using the nonlinear regression model under the condition of the minimum sum of squared differences. ra(t), ra(t – 1) and ra(t – 2) is the air temperature at time t, (t – 1), (t – 2). (6) in model (6), the water temperature at time t is determined based on the dependence of daily air temperature by the sine function in equation (4) and the lag over time (lag = 1 and lag = 2), corresponding to time t-1 (1 day before) and t-2 (2 days before) of air temperature equation (5). d. artificial neural networks -ann in recent years, ann has been applied quite widely in many areas related to estimation and forecasting due to high accuracy when complex nonlinear models are difficult to achieve by conventional mathematical equations [3, 17, 20]. in this study, ann model are used to identify the daily maximum water temperature with the neurons as input data of the maximum and average air temperature in a time period to determine the time lag between air and water temperature. figure 2 show the basic structure of ann consisting of three basic layers: (i) input layer (data layer entered input layer) are neurons x1, x2, ... xn; (ii) one or more hidden layers (processing data layer -hidden layer); and (iii) output data layer (output data layer created output layer). each layer in ann consists of nodes (neurons), each neuron connects to another neuron of the previous layer and moves from the data layer into the hidden layer to the output layer. in an ann there might be multiple hidden layers, each neuron in the hidden layer consists of three components, including weights; bias and activation function. the activation function mainly used is sigmoid function (including logsig, tansignonlinear function) or purelin linear function. asian review of environmental and earth sciences, 2019, 6(1): 1-8 4 © 2019 by the authors; licensee asian online journal publishing group figure-2. structure of ann model source: modified from srivastav, et al. [21] according to marijana, et al. [16] mathematically, neuron is calculated by the equation: y= (v) where: w[w1, w2…wn] vector of the weight x[x1, x2…xn] vector of input signal wn+1 bias (v) activation function ann associated with machine learning methods, in which input data is divided into 2 parts: training (80%) and testing (20%) data. the training data was used to determine the parameters of the proposed models then the model adjust the weight of each neuron and the error. the quality of the resulting models was assessed using the test dataset. the entire process performed by dedicated software. e. model evaluation the accuracy of the output is the factor deciding the model's efficiency and is usually done by evaluating some parameters. √ ∑ ̂ (7) ̅ √ ∑ ̂ (8) ∑ ̂ ∑ ̅ (9) ∑ ̅ ̂ ̅̂ √∑ ̅ ∑ ̂ ̅̂ (10) ̂ : water temperature prediction in day i : observed water temperature in day i ̅̂ : average value of ̂ ̅ : average value of n: size of data set root mean square error – rmse: the parameter describes the error between observed and calculated data it could be standardized by the percentage% (rmse%) to describe relativity to the mean value. correlation coefficient r: provides information about the linear relationship between the calculated value and the observed value. r value ranges from 0-1. the closer the r=1 value is, the closer the correlation is. nash and sutcliffe [22]: determine the effectiveness of the model. e assesses the relative difference between simulation value and observation value. e has a value of - to 1. the minimum e value of 0.9 specifies an acceptable model. 3. results and discussion in the study, the daily data including air and water observation at bai chay station of 10 years (2008-2017) are used and divided into 2 data sets: the data set from 2008-2014 is used as learning data (training data); the data set from 2015-2017 is used as testing data. the training data (air and water temperature data) are used for coefficient identifiation of regression models including: simple linear (equation 1); nonlinear regression model (equation 2); stochastic model (equation 5); artificial neural network model (variables in table 1). in the testing data, air temperature data and outputs of models identifying from training data were used to simulate water temperature. then, the results of comparision between simulated and observed water temperature were implemented through parameters rmse, r, e, lớp dữ liệu vào lớp ẩn lớp dữ liệu ra input layers hidden layer output layer asian review of environmental and earth sciences, 2019, 6(1): 1-8 5 © 2019 by the authors; licensee asian online journal publishing group  simple linear regression model the coefficients of a simple linear regression model are identified by training data set from 2008-2014 in excel software. the results determine parameters as follows: tw (t)=2.986+0.874*ta(t) figure 3 depicts the difference between the observed and the simulated data of the model. the evaluation of accuracy results are shown in table 2. in which, the correlation coefficient between water temperature and air temperature at bai chay station are r = 0.89; rmse = 1.68. however, nashsutcliffe coefficient e = 0.89 <0.9 shows, this model has a poor accuracy.  nonlinear regression model nonlinear regression model is applied similarly to linear regression model with logistic nonlinear regression in solver function in excel software for training data 2008-2014 . the output of model enable to identify parameter of equation (2) as follows: figure 4 depicts the difference between observed and simulated data of nonlinear regression models. the results of the model implementation are shown in table 2. in which, the correlation coefficient between water and air temperature at bai chay station is r = 0.9; root mean square error rmse = 1.6 and nashsutcliffe coefficient e = 0,9 shows that this model could be applied for the calculation of water temperature from air temperature values.  stochastic model by using the 2-day time lag (t-1) and (t-2), parameters of the stochastic model are calculated: [ ] in the table 2, the accracy indicators of model r = 0.94; rmse = 1.4; nashsutcliffe coefficient e = 0.92, show the stochastic model is the outperform of these regression model. figure 5 describes the correlation coefficient between water and air temperature at the bai chay station. it also show that the water temperature is not only influenced by the daily maximum air temperature but it is also greatly influenced by the temperature value of the previous 2 days. this means that when the air temperature rises or falls suddenly, the water temperature continues to fluctuate more slowly in about 2 days (48 hours).  artificial neural network model the calculation of network neurals is done by nntool of matlab 2018a software, through 3 steps step 1 : network training network training is done through a training data set. each mlp network configuration is performed with the maximum number of iterations 1000 times (1000 epoch). in the training set, input variables are neurons from mlp1 to mlp10 (table 1). through training data set, bias and weights through each loop are identified and adjusted. in this study, the algorithm used is feed-forward back drop, levenbergmarquardt (lma) algorithm– trainml in matlap software. table-1. variables in the artificial neural network model no neuron in the network interpretation 1 mlp1: ta_max consider the effect of daily maximum air temperature 2 mlp2: ta_max, ta_tb consider the effect of maximum and average daily air temperature 3 mlp3: ta_max, ta_tb , ta_tb -1 consider the correlation of 1 day lag of water temperature with air temperature 4 mlp4: ta_max, ta_tb, ta_tb -1, ta_tb -2 consider the correlation of the 2-day lag of the average air temperature with the water temperature ta_tb -2: daily average air temperature in 2 day before 5 mlp5: ta_max, ta_tb, ta_tb -1, ta_tb -2, ta_max -1 consider the relation of 1-2 day lag of average air temperature, maximum air temperature with water temperature 6 mlp6: ta_max, ta_tb, ta_tb -1, ta_tb-2, ta_max -1, ta_max -2 7 mlp7: ta_max, ta_tb, ta_max (0,1,2), ta_tb (0,1,2) consider the correlation of ta_max variation in 3 days, 1-2 day lag of average air temperature, maximum air temperature with water temperature 8 mlp8: ta_max, ta_tb, ta_max (0,1,2), ta_tb (0,1,2), ta_tb -1, ta_tb -2, ta_max -1, ta_max -2 considering the correlation of the average progress in 3 days 9 mlp9: ta_max, ta_tb, ta_max (0,1,2), ta_max -1, ta_max -2 considering the correlation between variation of ta_max in 3 days, 12 day lag of air temperature, max air temperature with water temperature 10 mlp10: ta_max, ta_max (0,1,2), ta_max 1, ta_max -2 consider the correlation of the progress and latency of max air temperature with water temperature source: defined by the author asian review of environmental and earth sciences, 2019, 6(1): 1-8 6 © 2019 by the authors; licensee asian online journal publishing group step 2: testing when the result of performing network training that satisfies the requirements of the number of iterations produces, the computer software will record the entire process with the weights, errors and adjustment coefficients of each iteration. this process then apply for target data to calculate water temperature prediction and to produce model results step 3: output evaluation evaluation of the accracy results is done by comparing the water temperature data measured and the water temperature generated from the model's testing data to identify the accuracy of the model. where: ta_max: daily maximum air temperature ta_tb: daily average air temperature ta_max (0,1,2): average of daily maximum air temperature of 3 days (present and 2 previous days); (0:present day; 1: 1 day before; 2: 2 day before) ta_tb (0,1,2): average of daily average air temperature of 3 days’ average (present and 2 previous days); (0:present day; 1: 1 day before; 2: 2 days before) ta_tb -1: daily average air temperature of 1 day before ta_tb -2: daily average air temperature of 2 previous days ta_max -1: daily maximum air temperature of 1 day before ta_max -2: daily maximum air temperature of 2 previous days the aim of the study is to find the best model for identifying the maximum water temperature through air temperature. therefore, the daily maximium and average air temperature are included in all models. mlp4, mlp5, mlp6 models additionally consider the correlation between the water temperature and air temperature with t-1 values: 1 day lag; t-2: 2-day lag; mlp7 and mlp8 models added elements of the effect of air temperature variation in 3 consecutive days (current day and 2 days before). the results of evaluation in each neuron network structure shown in the parameters in table 2, figure 6 show that mlp4 network model with mlp4 neurals: ta_max, ta_tb, ta_tb -1, ta_tb -2 give the outperform results with indicators rmse = 1.24, rmse% = 4.5%; correlation coefficient r=0.988 and e = 0.94. the comparison of rmse, r, e indicators show that the stochastic model and artificial neural network model with the same variables ta_max, ta_tb, ta_tb -1 ta_tb -2 give better results. from the output of the models, it can be seen that the daily maximum water temperature depends on: the daily average, maximum, and the average temperature of the 2 previous days. this also shows that the time lag of water temperature compared to air temperature is 2 days. table-2. indicators of accuracy models models rmse rmse% r e 1 simple linear regression 1,68 6,1 0,89 0,89 2 nonlinear regression 1,6 5,8 0,90 0,90 3 stochastic 1,4 5,1 0,94 0,92 4 ann mlp1 2 7,3 0,9 0,84 mlp2 1,759 6,4 0,97 0,88 mlp3 1,62 5,9 0,97 0,89 mlp4 1,24 4,5 0,988 0,94 mlp5 1,579 5,7 0,98 0,90 mlp6 1,558 5,7 0,98 0,90 mlp7 1,58 5,7 0,981 0,90 mlp8 1,556 5,7 0,987 0,90 mlp9 1,585 5,8 0,989 0,90 mlp10 1,59 5,8 0,98 0,90 source: authors’ calculation figure-3. simulated and observed water temperature in simple linear regression model source: data collected from bai chay station (e.g. of year 2008) asian review of environmental and earth sciences, 2019, 6(1): 1-8 7 © 2019 by the authors; licensee asian online journal publishing group figure-4. simulated and observed water temperature in nonlinear regression model source: data collected from bai chay station (e.g. of year 2008) figure-5. simulated and observed water temperature in stochastic regression model source: data collected from bai chay station (e.g. of year 2008) figure-6. simulated and observed water temperature in ann-mlp4 model source: data collected from bai chay station (e.g. of year 2008) 4. conclusions the study used the daily average, maximum air and water temperature data of bai chay station to assess output accuracy by implementing 03 regression models (linear regression, nonlinear, stochastic regression) and artificial neural network models. in particular, artificial neural network model was built with 10 network structures (mlp1-mlp10) to determine some factors of air temperature affecting variation and time lag of water temperature. the results of 14 models identified that ann-mlp4 model with 4 parameters ta_max, ta_tb, ta_tb -1, ta_tb -2 gave the best results with values of rmse = 1.24; r = 0.98; e = 0.94. the study allows to identify that:the maximum temperature of water (tw_max) depends greatly on the daily average and maximum air temperature . the time lag between the daily maximum air and water temperature in this sutdy applying for the coastal area of the northern delta, vietnam is 2 days. daily average temperature is important factors because it it take values of daily minimum and day and night temperature fluctuations. stochastic model examines seasonal and short-term fluctuations between air and water temperature. this model gave the best results in the regression methods implemented. ann model allows using complex input variables. this model should be considered for water temperature prediction as a base on disaster risk and climate change to aquaculture in coastal northern areas, vietnam. asian review of environmental and earth sciences, 2019, 6(1): 1-8 8 © 2019 by the authors; licensee asian online journal publishing group references [1] m. n. kutty, "site selection for aquaculture: physical features of water. lectures presented at arac for the senior aquaculturists course, electronic document in chapter 8." available: http://www.fao.org/docrep/field/003/ac174e/ac174e01.htm#ch1, 1987. [2] s. zhu, e. k. nyarko, and m. hadzima-nyarko, "modelling daily water temperature from air temperature for the missouri river," peer journal, vol. 6, p. e4894, 2018. [3] d. caissie, "the thermal regime of rivers: a review," freshwater biology, vol. 51, pp. 1389-1406, 2006.available at: https://doi.org/10.1111/j.1365-2427.2006.01597.x. [4] r. anamarija, "modelling river temperature from air temperature: case of the river drava (croatia)," hydrological sciences journal des sciences hydrologiques, vol. 60, pp. 1490-1507, 2014.available at: http://dx.doi.org/10.1080/02626667.2014.914215. [5] h. li, x. deng, d. y. kim, and e. p. smith, "modeling maximum daily temperature using a varying coefficient regression model," water resources research, vol. 50, pp. 3073-3087, 2014.available at: https://doi.org/10.1002/2013wr014243. [6] b. loubna, d. caissie, a. st-hilaire, t. b. ouarda, and b. bobée, "a review of statistical water temperature models," canadian water resources journal, vol. 32, pp. 179-192, 2007.available at: https://doi.org/10.4296/cwrj3203179. [7] b. a. sinokrot and h. g. stefan, "stream temperature dynamics: measurements and modelling," water resources research, vol. 29, pp. 2299–2312, 1993.available at: https://doi.org/10.1029/93wr00540. [8] b. webb and f. nobilis, "long-term perspective on the nature of the air–water temperature relationship: a case study," hydrological processes, vol. 11, pp. 137-147, 1997.available at: https://doi.org/10.1002/(sici)1099-1085(199702)11:2<137::aidhyp405>3.0.co;2-2. [9] j. c. morrill, r. c. bales, and m. h. conklin, "estimating stream temperature from air temperature: implications for future water quality," journal of environmental engineering, vol. 131, pp. 139-146, 2005.available at: https://doi.org/10.1061/(asce)07339372(2005)131:1(139. [10] o. mohseni, h. stefan, and t. erickson, "a non-linear regression model for weekly stream temperatures," water resources research, vol. 34, pp. 2685–2692, 1998.available at: https://doi.org/10.1029/98wr01877. [11] o. mohseni, t. r. erickson, and h. g. stefan, "sensitivity of stream temperatures in the united states to air temperatures projected under a global warming scenario," water resources research, vol. 35, pp. 3723-3733, 1999.available at: https://doi.org/10.1029/1999wr900193. [12] v. m. vliet, f. ludwig, j. zwolsman, g. weedon, and p. kabat, "global river temperatures and sensitivity to atmospheric warming and changes in river flow," water resources research, vol. 47, p. w02544, 2011.available at: https://doi.org/10.1029/2010wr009198. [13] b. ahmadi-nedushan, a. st-hilaire, t. b. ouarda, l. bilodeau, e. robichaud, n. thiémonge, and b. bobée, "predicting river water temperatures using stochastic models: case study of the moisie river (québec, canada)," hydrological processes: an international journal, vol. 21, pp. 21-34, 2007.available at: https://doi.org/10.1002/hyp.6353. [14] a. rabi, m. hadzima-nyarko, and m. šperac, "modelling river temperature from air temperature: case of the river drava (croatia)," hydrological sciences journal, vol. 60, pp. 1490-1507, 2015.available at: https://doi.org/10.1080/02626667.2014.914215. [15] v. kothandaraman, "analysis of water temperature variations in large rivers," journal of the sanitary engineering division, vol. 97, pp. 19–31, 1971. [16] h.-n. marijana, r. anamarija, and š. marija, "implementation of artificial neural networks in modeling the water-air temperature relationship of the river drava," water resour manage, vol. 28, pp. 1379–1394, 2014.available at: 10.1007/s11269-014-0557-7. [17] g. sahoo, s. schladow, and j. reuter, "forecasting stream water temperature using regression analysis, artificial neural network, and chaotic non-linear dynamic models," journal of hydrology, vol. 378, pp. 325-342, 2009.available at: https://doi.org/10.1016/j.jhydrol.2009.09.037. [18] j. t. deweber and t. wagner, "a regional neural network ensemble for predicting mean daily river water temperature," journal of hydrology, vol. 517, pp. 187-200, 2014.available at: https://doi.org/10.1016/j.jhydrol.2014.05.035. [19] d. a. cluis, "relationship between stream water temperature and ambient air temperature: a simple autoregressive model for mean daily stream water temperature fluctuations," hydrology research, vol. 3, pp. 65-71, 1972.available at: https://doi.org/10.2166/nh.1972.0004. [20] n. sivri, h. k. ozcan, o. n. ucan, and o. akincilar, "estimation of stream temperature in degirmendere river (trabzon-turkey) using artificial neural network model," turkish journal of fisheries and aquatic sciences, vol. 9, pp. 145–150, 2009. [21] r. k. srivastav, k. p. sudheer, and i. chaubey, "a simplified approach to quantifying predictive and parametric uncertainty in artificial neural network hydrologic models," water resources research, vol. 43, p. w10407, 2007.available at: https:// doi:10.1029/2006wr005352. [22] j. e. nash and j. v. sutcliffe, "river flow forecasting through conceptual models. part a. discussion of principles," journal of hydrology, vol. 10, pp. 282-290, 1970.available at: https://doi.org/10.1016/0022-1694(70)90255-6. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://www.fao.org/docrep/field/003/ac174e/ac174e01.htm#ch1, http://dx.doi.org/10.1080/02626667.2014.914215 18 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 18-29, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.18.29 © 2021 by the authors; licensee asian online journal publishing group the dynamics of land use land cover and its driving forces in mekelle city region, ethiopia shishay kiros weldegebriel1 kumelachew yeshitela2 ( corresponding author) 1ethiopian civil service university, addis ababa, ethiopia. 2ethiopian institute of architecture, building construction and city development, addis ababa university, addis ababa, ethiopia. abstract the rationale of this study was to study the spatio-tempo lulc dynamics over the past 47 years and identifying the major drivers of these changes. it was conducted in mekelle city region, northern ethiopia which is highly susceptible to environmental degradation. this landscape-scale level study employs a combination of analysis of satellite imageries, information from field studies, document review, key informant interview and observation. digital satellite images were processed, classified and analysed by erdas imagine. computations of the area changes in the land use categories was made using supervised classification by applying maximum likelihood classifier algorithm and finally post-classification change detection technique was undertaken using arc gis 10.5.1. for stastical analysis of variables spatial autocorrelation and structural equation model was used. during the study period between 1972 and 2019 about 60,705.56 hectares of the total landscape of the study area was converted from one lulc type to another. the findings show increase was observed in cultivated land, built-up area and bushes and shrubs. on the other hand, natural forest, water body and bare lands were dramatically declined. among the driving factors; climate variability, population growth, dem and slope were identified as the leading land use and land cover change drivers. thus, spatial planners need to take these drivers into consideration and make sound decisions regarding changes in lulc during decision makings. keywords: city region, drivers, erdas, land use/land cover changes, remote sensing, spatio-tempo. citation | shishay kiros weldegebriel; kumelachew yeshitela (2021). the dynamics of land use land cover and its driving forces in mekelle city region, ethiopia. asian review of environmental and earth sciences, 8(1): 18-29. history: received: 3 may 2021 revised: 7 june 2021 accepted: 30 june 2021 published: 13 july 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: my thanks go to tigray bureau of trade, industry and urban development, tigray (ethiopia), bureau of civil service and ethiopian civil service university for giving the opportunity to pursue this study, without which this achievement would not have been possible. authors would like to thank all institutions and individuals at national, regional, district and city levels who provided them information for this study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 19 2. material and methods ..................................................................................................................................................................... 19 3. results ................................................................................................................................................................................................ 21 4. discussion .......................................................................................................................................................................................... 26 5. conclusion and recommendations ............................................................................................................................................... 28 references .............................................................................................................................................................................................. 28 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2021.81.18.29&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.asianonlinejournals.com/index.php/arees/article/view/3072 https://orcid.org/0000-0002-6140-9884 asian review of environmental and earth sciences, 2021, 8(1): 18-29 19 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes to the generation of scientific knowledge for the scientific community on understanding environmental degradation using multi-lens approach to sustain the environment, improved research tool/ technique and it will have implications for positive social change. 1. introduction the imminent of humankind depends on whether or not we have a vision to guide transition toward sustainability, on scales ranging from local landscapes to the planet as a whole [1].the fundamental concept in landscape development has always been that people are part of the landscape and that landscapes are changed for their benefit [2]. in order to meet increasing human needs natural ecosystems have been converted into different land uses since humans first began to manage their environment. however, the changes that have taken place over the last 50 years have been especially important and intense as society is becoming increasingly urbanized, while natural ecosystems become deteriorated [3]. land uses/land covers are closely related to the ecosystem services supply of provisioning, regulating, supporting and cultural ecosystem services provisions [4].the dynamics of an ecosystem are strongly affected by natural and human disturbances, and such changes can have direct and cascading effects on the spatial and temporal variations of ecosystems [2]. the notion of driving forces is gaining increasing attention in landscape change research [5]. drivers of degradation can be many and complex, resulting from a range of different interactions over time and space [6]. anthropogenic drivers, such as population growth have mostly a short-term and often more perceivable impact than biophysical drivers. conversely, climate change as one of the emerging drivers of land use /land cover dynamics and is difficult to detect and quantify in the short term. subsequently, long-term studies are necessary to provide evidence of climate change [7]. cities do not operate in isolation but within a sphere of dependence on surrounding areas and their ecosystems. cities depend on persisting flows of goods and services coming from other neighbouring non-urban ecosystems to sustain fundamental urban functions.ecological principles of land use advocate to examine the impacts of local decisions in a regional context [8]. mekelle city is dependent on the ecosystem services beyond the city limits. mekelle city has not been studied as a complete network with consideration of all ecosystem sources from its hinterlands. an increasing number of studies demonstrate the need of applying a social-ecological system approach in ecosystem services. however, there is a lack of empirical research that operationalizes the concept of social-ecological system in a spatially explicit. several efforts have been made to improve the quantification of lulc changes and their drivers. from the reviewed literatures there are still deficiencies and methodological inconsistencies. alternative approaches to better understand the problem is useful. hence, studying landscape dynamics and its driving forces in mekelle city region, northern ethiopia through a social-ecological systems perspective under different spatial and temporal scales can support decision-making in land use to understand past, current and plausible future changes in land use. therefore, the objectives of this study were: to assess land use/land cover dynamics, analyze the driving forces of land use/land cover change and suggest possible spatial planning solutions for sustainable watershed ecosystem services provision. 2. material and methods 2.1. study area mekelle city and its hinterlands which are significant in terms of watershed ecosystem services for the metropolitan city are named as city region (figure 1). the landscape is located within tigray region, northern part of ethiopia found in west 39.362942, east 39.687048, north 13.680920 and south 13.342621 about 760.61 km north of addis ababa and the area covered in this investigation is 897.12 square kilometers (89,712 hectares). the study area is characterized by varied topographic conditions. the elevation ranges from 1700 meters in the geba river to 2685 meters ellala and gebat river catchment. the core city of the study area mekelle city is 2062 m above sea level. the climate is predominantly semi-arid with irregular rainfall and frequent drought periods. the mean annual rainfall of the is estimated to be less than 532 mm [9]. climatically, the area has a semiarid climate with little variation and it is knowns by its environmental vulnerability [10]. the agro-climatic zone of the study area is mild climatic condition. the monthly mean minimum temperature is 150c and maximum monthly temperature may go as high as 280c. the study area population is 556127 [11]. 2.2. data sources and processes this landscape-scale level study employs a combination of analysis of satellite imageries of 47 years and information from field studies, document review and key informant interview. in order to detect lulc dynamics data from landsat series was extracted (table 1) which is found at (https://earthexplorer.usgs.gov/.key informant selection was made based on the information gathered from knowledgeable local elders; based on their age, duties and responsibility in their local community. remotely sensed data, document review analyses add to validate the relevance of the local elderly interview results. in addition to this, the author made observations and described about what was observed. a global positioning system was used during the field survey for accuracy assessment. the years for analysis were selected based on key signs of lulc change, e.g. land degradation, land policy changes, rapid urbanization, rapid population growth, socio-economic development and finally the availability of satellite image. images from the same period (november–january), i.e., immediately after the rainy season, was selected in order to minimize the seasonal effect on the classification results. probability and non-probability sampling techniques was employed. snowball sampling was employed for reaching local elderly persons. the population of lulc was divided into sub-populations of known size, and then random samples was taken from each stratum. in each category, random samples were further determined for field investigation. since it is difficult to cover, collect data from whole population of ecosystem from all types of lulc for ground truthing using gps it was selected proportional from all the city region by employing an accuracy assessment framework. the maps were further verified from the pre-determined sites through observations and consulting with 15 local residents. the 450 corroboration points, which were spatially and temporally distributed in the whole study area encompassing all nine lulc types table 2 were sampled through stratified random sample. https://earthexplorer.usgs.gov/ asian review of environmental and earth sciences, 2021, 8(1): 18-29 20 © 2021 by the authors; licensee asian online journal publishing group figure-1. location map of the study area. source: prepared based on arc gis online data by the author, 2019. table-1. specifications of satellite images that was utilized in this study. satellite sensor path row resolution (m) acquisition date landsat 1 mss multispectral c1 level 1 181 50 60 02 november,1972 landsat 5 tm multispectral c1 level 1 169 51 30 22 november,1984 landsat 5 tm multispectral c1 level 1 168 51 30 21 november,1992 landsat 5 tm multispectral c1 level 1 168 51 30 30 november,2001 landsat 7 etm+ multispectral c1 level 1 168 51 30 20 november,2012 landsat 8 operational land imager oli/tirs c1 level 1 169 51 30 23 january,2019 table-2. descriptions of identified lulc classes. lulc class description built-up area built-up area encompasses land on which buildings and non-building structures are present, such as urban area of mekelle city and its suburban area ,developed land lot including roads,rural area, small towns and villages grassland land under grass cover but highly managed for grazing and feeding of domestic animals, selling for various purposes. a land dominated by natural grass, small herbs and grazing lands. cultivated land areas of land prepared for growing agricultural crops. this category includes areas currently under crop, irrigated agricultural and land under preparation or fallow land. bushes and shrubs land covered with shrubs, bushes, and small trees with little woody vegetation mixed. specific area characterized by scattered bushes and shrubs and trees. areas covered by low woody of 3 m in height, multiple stems, vertical growing of bushes and shrubs with canopy cover between 5 and 50%. examples like acacia locally known as “hohot”, aloe barbadensis, “ika” and ocimun lamiifolium. water body surface water or all areas of open water areas covered with water either along the river bed or man-made including rivers, streams, swales, dams, lakes, wetlands, ponds and reservoirs natural forest high and dense natural forest and in churches and reserved areas. bare lands land left without vegetation cover (devoid vegetation), eroded land due to land degradation and weathered road surface and includes rock, including exposed soils, stock quarry, rocks, and areas of active excavation and vacant land within mekelle city plantation forest areas covered by man-made trees including sparse forests examples include; eucalyptus tree, acacia and teak riverside vegetation plants growing in areas adjacent to rivers and streams in both urban and rural (riparian vegetation include trees, shrubs, grasses and trees with canopy.) 2.3. data analysis digital satellite images were processed, classified and analysed using erdas imagine remote sensing software package 2015. computations of the area and changes in the land use categories was made using arc gis 10.5.1. supervised classification was performed on the image's pixels of the different lulc classes. this was done by training the areas (assigning pixels to land use classes) based on the previous knowledge of the area. before classifying, the image was pre-processed in erdas software. the image was atmospheric corrected. landsat 7 etm+ since 2003 to present has gaps in their data due to scan line corrector (slc) failure. before analysis started scanning line corrector (slc) was employed using slc corrected in arc gis. the lulc of several years was converted to feature class(polygon) using arc gis conversion tool and using analysis tool of over lay tool using intersecting tool were merged into one polygon and then the 6 polygons were merged into single polygon. then it was used calculate geometry to calculate the changes in hectares. the lulc change detection lulc map of 1972 was re-sampled from 60m to 30 meters to match the spatial resolution of all the classified maps. spatial autocorrelation (moran’s i) was used to derive detailed information of the spatial and temporal variation of the land-use land cover dynamics using a spatial statistics tool analyzing patterns in arc gis. to understand the possible drivers of changes structural equation model using stata was used table 6. https://en.wikipedia.org/wiki/land https://en.wikipedia.org/wiki/building https://en.wikipedia.org/wiki/nonbuilding_structure https://en.wikipedia.org/wiki/urban_area https://en.wikipedia.org/wiki/urban_area https://en.wikipedia.org/wiki/suburb https://en.wikipedia.org/wiki/land_lot https://en.wikipedia.org/wiki/rural_area https://en.wikipedia.org/wiki/town https://en.wikipedia.org/wiki/village asian review of environmental and earth sciences, 2021, 8(1): 18-29 21 © 2021 by the authors; licensee asian online journal publishing group 3. results 3.1. accuracy assessment to assess the accuracy, first visual inspection for the image acquired from landsat series was compared with lulc map prepared and with shape file the study area, local maps and google earth were used as first necessary step. since this is not sufficient, quantitative accuracy assessmentt have made. to examines the accuracy assessment of land use land cover classified was done using erdas imagine 2015 accuracy assessment tool, for the year 2019 based on user defined 450 points collected referenced data using hand held gps table 3. total accuracy = number of correct plots *100 total number of reference data accuracy total = 409/450*100 = 90.88 % the error percentage, is the number of sites incorrectly classified divided by 450 or 41/450 = error, = 9.12%. the overall accuracy and kappa coefficient of the 2019 map were 90.88% and 91.64%, respectively which is acceptable in both accuracy total and kappa accuracy. table-3. comparing user's and producer's accuracies. s. n class name reference total classified total number correct producer accuracy user accuracy 1 built-up area 50 49 48 96 97.95 2 natural forest 50 44 44 88 10 3 plantation forest 50 55 47 94 85.45 4 water bodies 50 49 49 98 100 5 cultivated land 50 56 46 92 82.14 6 grass land 50 53 45 90 84.90 7 bushes and shrubs 50 49 48 96 97.95 8 river side vegetation 50 47 39 78 82.97 9 bare land 50 45 43 86 95.55 total 450 447 409 90.88 91.87 the user and producer accuracy for any given class typically were not the same. in the above examples the producer’s accuracy (it is the number of reference sites classified accurately divided by the total number of reference sites for the class) for the built-up class is 96% while the user's accuracy (it was calculated by taking the total number of correct classifications for a particular class and dividing it by the row total or the total number of classified sites) was 97.95%. this means that even though 96% of the reference built-up areas have been correctly identified as built-up area, only 97.95% percent of the areas identified as built-up areas in the classification were actually built-up areas. cultivated land (2) areas were mistakenly classified as built-up areas. by analyzing the various accuracy and error metrics we can better evaluate the analysis and classification results. 3.1.1. land use/land cover change dynamics and change detection in mekelle city region the multi-temporal lulc results and the variations for the years 1972, 1984, 1992,2001,2012 and 2019 (figure 2 and table 5) illustrate in 1972 the area was occupied by different classes of built-up area, natural and plantation forest, water body, cultivated land, grass land, bushes and shrubs, river side vegetation and bare lands. the study area witnessed large amount of agriculture land converted into settlements and other urban development activities. water bodies decreased. dense forest comprising all land with tree cover of canopy density was significantly declined. the results from the classified image of 1972 illustrate that at the beginning of the study year 66.78 % of the area was occupied by three land use classes only namely cultivated land, bare land and water body consecutively. and 26,403 ha (29.43%), 19936 ha (19.99%),15,577 ha (17.36%),11,132(12.42%),8183 ha (9.12%),5543(6.18%),2359 ha (2.63%),2082ha (2.32%) and 497 ha (0.55%) was cultivated land, bare land, water body, river side vegetation, bushes and shrubs, natural forest, plantation forest, grass land and built-up area consecutively. the end of the study period 2019 reveals that cultivated land, bushes and shrubs and built-up land have tremendously expanded at the expenses of other ecosystem types. currently,64,843 ha (72.27%),13,215 ha (14.73%),8897 ha (9.92%),1235(1.38)497 ha (0.55 %),330 ha (0.37%),326 ha (0.36 %),263 ha (0.29), and 106 ha (0.13%) are cultivated land, bushes and shrubs, built-up area, river side vegetation, plantation forest, grass land, bare land, water body, and natural forest consecutively. 3.1.2. land-use and land-cover change matrix the lulc changes matrix from 1972-2019 (table 4) showed that; in sum, 749 hectares converted from builtup to other classes. however, there was no transformation from built-up to natural forest. another 5427.73 hectares were converted from natural forest to other classes. this result showed majority of the natural forest was converted to cultivated land. of the changed area, 1585 hectares converted from plantation forest to other classes. this result showed majority of the natural forest was converted to cultivated land. there was no transformation from water body to bushes and shrubs. in sum, 15314 hectares converted from water bodies to other classes. this result showed majority of the water bodies was converted to cultivated land followed by grass land and built-up areas. similarly, 5160 hectares were converted from cultivated land to other classes. this result showed majority of cultivated land was converted to built-up areas. compared to the other lulc, 2029.03 hectares were also converted from grass land to other classes. this showed majority of the grass land was transformed to cultivated land. similarly, 2933.8 hectares converted from bushes and shrubs into other classes and majority of the bushes and shrubs was converted to cultivated land. on the other hand, 9897 hectares converted from river side vegetation into other classes. this result showed majority of the bushes and shrubs were converted to cultivated land. finally, 17610 hectares converted from bare lands into other classes. this result revealed majority of the class was converted to cultivated land. asian review of environmental and earth sciences, 2021, 8(1): 18-29 22 © 2021 by the authors; licensee asian online journal publishing group table-4. summary of lulc change matrix in hectare from 1972 to 2019. to from built-up area natural forest plantation forest water body cultivated land grass land bushes and shrubs riverside vegetation bare land total (2019) built-up area 42.9 0.74 0.40 1726.6 3516.72 0 1.44 522.31 3676.2 9487.31 natural forest 0 12.2 1.30 0.24 1.02 0.55 4.2 0.45 0.15 20.11 plantation forest 8 349 539.34 43.43 76 0.90 118 7.45 3.66 1145.78 water bodies 439.17 332 63.33 0 0 27.73 0 1519 0 2381.23 cultivated land 125.99 3954.2 419.13 11077.93 902.84 1800.8 1614 6277.13 8915.06 35087.08 grass land 0.090 1.41 0 2037 13.54 101.3 19.3 2.75 31.51 2206.9 bushes and shrubs 117.18 0 138.3 0 4.24 71.92 767.08 1000 1635.8 3734.52 river side vegetation 14.70 775.37 422.27 174.1 264.76 7.1 383.22 36.73 31.72 2109.97 bare land 1 2.81 0.93 254.7 380.88 18.73 26.56 531.18 3315.9 4532.69 totals (1972) 749 5427.73 1585 15314 5160 2029.03 2933.8 9897 17610 60705.56 table-5. area of classified lulc classes during 1972–2019. s.n class name 1972 1984 1992 2001 2012 2019 area (ha) % area area (ha) % area area (ha) % area area (ha) % area area (ha) % area area (ha) % area 1 built-up area 497 0.55 536 0.60 541 0.61 1029 1.15 4420 4.94 8897 9.92 2 natural forest 5543 6.18 1011 1.13 647 0.72 181 0.20 147 0.16 106 0.13 3 plantation forest 2082 2.32 1118 1.25 529 0.59 398 0.44 292 0.33 497 0.55 4 water body 15577 17.36 14209 15.83 2024 2.26 1207 1.35 130 0.14 263 0.29 5 cultivated land 26403 29.43 40156 44.76 65700 73.23 70003 78 69610 77.59 64843 72.27 6 grass land 2359 2.63 1049 1.17 310 0.35 297 0.33 445 0.5 330 0.37 7 bushes and shrubs 8183 9.12 16149 18 12559 13.99 9404 10.48 10982 12.24 13215 14.73 8 river side vegetation 11132 12.42 9359 10.42 1277 1.42 4907 5.47 1430 1.59 1235 1.38 9 bare land 17936 19.99 6134 6.84 6125 6.83 2286 2.58 2256 2.51 326 0.36 total 89712 100 89712 100 89712 100 89712 100 89712 100 89712 100 asian review of environmental and earth sciences, 2021, 8(1): 18-29 23 © 2021 by the authors; licensee asian online journal publishing group in the above table the row total sums the amount of land area for each lulc types of the year 1972 and column total sums the amount of land area that was converted to each lulc types of the year 2019. the bold diagonal values represent the area of each lulc class that remained unchanged while the off-diagonal values represent the changed area. the values in each of the cells represent the amount of land that was converted from one lulc type to another. the transition probability matrix showed that during the study period between 1972 and 2019 about 60705.56 ha of the total landscape of the study area was converted from one lulc type to the other. from all lulc types, built-up area experienced the lowest persistence with 749 ha conversion to another land use type, whereas bare lands and water bodies was the most persistent with 17610 hectares and 15314 hectares respectively. figure-2. lulc map showing the spatial distribution of the 1972, 1984, 1992, 2001, 2012 and 2019 classified images. asian review of environmental and earth sciences, 2021, 8(1): 18-29 24 © 2021 by the authors; licensee asian online journal publishing group figure-3. spatial autocorrelation of the temporal and spatial trend of lucc. from the spatial autocorrelation report, the p-value result indicates there is strong evidence of rejecting the null hypothesis. the null hypothesis ho: there was no significant change in land use pattern of the city region in the past 47 years is clearly not rejectable. hence, the h1: is accepted there was a significant change in the land use pattern of the city region. the high z-scores 12.455885 is associated with very small p-values. morgan’s index is 0.965981 which is positive spatial autocorrelation and shows values that are clustered. 3.2. drivers of lulc dynamics in mekelle city region in the study area, both population number and population density (figure 4 ) were increased from 93,163 in 1972 to 556127 in 2019 [12]. the population density in the mekelle city region within 47 years increased from 104 to 620 which is greater than the initial period by 596.15 % persons per square kilometer between 1972-2019 and higher than the national average in 1972 i.e., 30.14 person per square km. the current population density is much higher than the national population density of ethiopia which is 109.22 people per square km as of 2018. figure-4. population growth and density. the number of populations is continuously increasing. at the same time, the resource consumption per capita shows increment. this has leads to an increasing dependency on the city regions on ecosystem service. the city still depends on its hinterland for the provision of water, several ecosystem services and the most important and largest material flux into urban ecosystems. demographic change was the most important indirect driver for changing ecosystem services in the study area. the land use dynamics increased with population density change. asian review of environmental and earth sciences, 2021, 8(1): 18-29 25 © 2021 by the authors; licensee asian online journal publishing group 3.3. climate variability the study scrutinizes the historical climatic from 1972–2018(figure 5) and the consequence these had on lulc changes in mekelle city region. temporal changeability of climatic conditions, such as temperature happened over the last 47 years in mekelle city region. figure-5. climate variability in the study area. table-6. structural equation model regression results fitting target model: iteration 0: log likelihood = -1328.0484 iteration 1: log likelihood = -1328.0484 structural equation model number of observations = 54 estimation method = ml log likelihood = -1328.0484 oim coef. std. err. z p>z [95% conf. interval] structural lulcc < tem 0.014197 0.0151089 0.94 0.000 0.015416 0.04381 rai 0.0000957 0.0001963 0.49 0.000 0.0002891 0.0004805 pop 0.0027972 0.0003235 8.65 0.000 0.0021631 0.0034313 dem 0.0010578 0.000098 10.79 0.000 0.0008657 0.0012499 slope 0.0346079 0.0018498 18.71 0.000 0.0309824 0.0382334 dis -0.4366216 0.0486337 -8.98 0.000 -0.531942 -0.3413013 _cons -1.439772 .4447163 -3.24 0.001 -2.3114 -0.5681439 var(e.lulcc) 0.0177041 0.0034072 0.0121412 0.025816 lr test of model vs. saturated: chi2(0) = 0.00, prob > chi2 = the results show the six drivers namely temperature, rainfall, population, dem, slope, and distance have significantly affected lulc changes in the study area in the past five decades. the biophysical factors terrain characteristics (slope and elevation) areas among the main factors causing land-use change. based on sem model the p-value for each non-stationary lulc driving force indicates for all the six drivers the p-value is < 0.05. hence, there is strong evidence to reject the ho: driving forces of land use patterns do not bring lulc changes. 3.3.1. local elderly persons perceptions on driving forces the key informants described that there was substantial dependency on wood for house hold consumption and this was a threat to various ecosystems like forest, bushes and shrubs, riverine vegetation that cause of environmental degradation. furthermore, farmers clear the forest and change the land into cultivated land. according to key informants during the imperial times, the customary land tenure contributed to the expansion of settlements and agriculture. they believe the observed speedy expansion of cultivation and built-up expansion attributed to the policy and strategy changes. agricultural encroachment on other lands and expanding built-up areas. such changes in land use patterns have also been observed all part of the study area. wetlands are destroyed and replaced by infrastructure, farmland, housing development. according to the qualitative data obtained through interview, the climatic condition has changed significantly. they described a trend towards a shorter rainy season that starts later and finishes earlier with a relatively less predictable pattern. particularly, the major events that brought lulc changes include: the severe droughts of 1984/85. this increased the pressures on the ecosystem, resulting in an expansion of cultivation; increase in dry years during the last 3 decades; and rapid population growth that increases the demand for various ecosystem services. furthermore, many churches were built using the wood from these areas. one of the local elderly persons from an area known as shibta stated that “rain are no longer coming in the beginning of june but start to rain in mid-june and end in the mid of august. in the past, they were getting rainfall from mid-may/ early june till the end of september and mid-october. and the extent of the rain seasons has decreased and only get rainfall for two months or less’. as a result, declining of rivers and streamflow is threatened the ecosystem and the provision of drinking water’’. asian review of environmental and earth sciences, 2021, 8(1): 18-29 26 © 2021 by the authors; licensee asian online journal publishing group 4. discussion landsat series and semi-structured interview has been used in analyzing lulc changes. this study utilizes erdas imagine software synchronized with google earth which is currently worldwide used technology. the spatio-temporal analysis is not possible through other lulc analysis and mapping software. because synchronization of google earth with erdas imagine increase the lulc classification accuracy of different resolutions. on the basis of interpretation of remote sensing imageries, field surveys and interview with local elderly persons and existing study area geographical conditions, the study have classified the study area into nine categories. the different types of the lulc classes have experienced significant changes during past 5 decades in the various parts of the study area. many methods of accuracy assessment have been reviewed in the remote sensing literature and the most widely promoted and used, is confusion or error matrix [13]. the study used error matrix for accuracy assessment. without accuracy assessment the quality of map or output produced would be of lesser value to the end user. supervised and unsupervised techniques show different levels of accuracy after accuracy assessment was conducted. therefore, this study used supervised image classification based on the knowledge area of the study area to increase the accuracy of the remote sensed data. in an accuracy assessment of map data, the map was compared with higher quality data, reference data collected by ground survey through sample-based approach. in the 1972 the results show that mekelle city region was rich in various ecosystem types particularly the water body such as the rivers and streams were perennial that has continuous flow of water all year round during years of normal rainfall, and there was rich river side vegetation and currently the rivers and stream water is temporary and flow ceases immediately after the rainy season as per the information obtained from local elderly persons and the researcher knowledge of the study area. on the other hand, at the end of the study period 2019 reveals that cultivated land, bushes and shrubs, built-up land has tremendously expanded at the expenses of other ecosystem types. despite it is a dominant classis of cultivated land it has showed reduction comparing with previous study decades. the lulc analysis from remote sensing was supported by observations and perceptions from the ground. the observed changes are investigated from satellite images and from the ground through interviews. the remote sensed results provide valuable understandings the city region lulc changes, which could not have been captured through other sources of data in short period of time. from the interview it is proved that decreased in water body, natural forests, river side vegetations while cultivated land and built-up areas has increased tremendously between the years 1972 and 2019. the qualitative data generated a deeper understanding of the lulc change and discovered the shrinkages of various ecosystem types. the limitations of satellite data were supported with qualitative data. the local communities on the lulc change considerably agree with data from satellite images analysis. the remote sensing result corresponded quite well with the qualitative data findings from local elderly persons. through comparing both quantitative and qualitative data the differences and similarities between them has been proved. various land use/ land cover types are transformed or interchanged into another one or more forms. the results of the study agree with other scientific local studies previously conducted on lulc changes at river basin level. the study area is part of the great giba river basin and the results shows there is a significant lulc changes. a study by gebremicael, et al. [14] in tekeze-atbara basin, ethiopia on longitudinal land use change from land degradation shows 72% of the landscape has changed its category during the past 4 decades but recently increasing of vegetation cover resulted from intensive watershed management programs has been recorded. the geba basin is one of the most water stressed areas of ethiopia, with only a short rainy period from mid-june to mid-september due to consistent erratic rainfall in both time and space in the last decades [15]. in agreement to the result of this study teferi, et al. [16] showed that swap change of the gains and losses among lulc categories is more important in recognizing the total change than the net change. according to abraha [17] a study in giba catchment the land use is dominated by cultivated land, followed by bushed, grassland and bare land. grasslands, forests, water bodies, and built-up areas only cover small fractions of the catchments. the observed data show several ecosystems are dramatical losing and an increase in built-up area, cultivated land, bushes and shrubs due to land use dynamics. according to millennium ecosystem assessment [18] in recent years, african grassland, woodland, and other vegetated areas have increasingly been converted into cropland and other land uses. in the study area, similar tendency has been found where cultivated land and built-up areas have increased tremendously. the findings from both quantitative and qualitative data proves the worth of combining remote sensing with local perceptions have principal role in to understand land use dynamics. qualitative data alone cannot capture the large-scale patterns of lulc changes. but quantitative data from remote sensing provides a valuable indication of lulc changes, which was explored more in-depth using qualitative data. in recent years few studies have attempted to link community levels data, observation to remotely sensed data on lulc changes. the local elderly person perception about the last 47 years increased the confidence of the spatial data results. the lulc trend changes in the study area have generated ecosystem services sustainability challenges. here, identifying more sustainable land-use options requires solid theoretical foundations on the major causes of those changes. understanding the lulc change from the perspective of socioecological system is vital for designing strategies to address the sustainability challenges. the complex and diverse interactions among social-ecological systems make hard to identify and quantify the main drivers of lulc changes [19]. to fill this gap, the study used biophysical and anthropogonic drivers followed by mixed research approach to identify the key drivers for lulc changes. analysis of lulc changes at multiple scales demands conceptual frameworks and analytical methods that are both comprehensive enough to capture the dynamics of society-environment interactions at different scales [20]. the 1972 satellite image of the study area showed there were relatively undisturbed areas that had been serving as a home of various ecosystem with varying levels of density and ground cover. this data is also corroborated by the key informants. based on evidence obtained from the local elderly persons, cultivated land, water body, natural forest and bare land were the major lulc classes during in 1970s. during this period the ownership of land was feudal and most of the land was rich in ecosystem. the spatial analysis of the 1972 image asian review of environmental and earth sciences, 2021, 8(1): 18-29 27 © 2021 by the authors; licensee asian online journal publishing group revealed that cultivated land constituted the largest proportion of land. this is because, during the 1972 the area was characterized as relatively low population. the built-up area increment was huge starting from the year of 2001 and was increased from 541 ha to 1029 ha of previous study period 1992 which was increased by 90.2%; the built-up area of the year 2012 was greater than 2001 by 3391 ha (329.5%) and the increment of year 2019 was greater than 2012 by 4477 ha (101.3%). these results show that the built-up area rapidly grow from 2001 onwards. the expansion of both rural and urban settlement and infrastructure expansion took the largest share by converting other land cover types. this was aggravated due to continuous increase of population number they need additional land for settlement area. the expansion of cultivated land as shown on the satellite images was confirmed by the key informants that indicated that the land conversion was caused by the high numbers of the youths, who were looking for land because no employment opportunities outside agricultural sector was available at that time. farmers have been exchanging land among themselves through various arrangements to be able to grow food in proximity to their residence. the expansion of cultivated land as shown on the satellite images was confirmed by interviews with inhabitants that indicated that the land conversion was caused by the high numbers of the population growth. in line with this, globally population growth has been positively associated with the expansion of agricultural and urban land, land intensification, and deforestation [21]. this expansion of agriculture was supported by government plans and created opportunities to be expanded. between the mid-1975s and mid-1980s, the lulc changes were encouraged by government policy on agriculture and land tenure, and readily bought into by farmers accelerated. these drivers contributed to a transformation in the land use patterns. during the military government derg after 1975 made efforts to improve the agricultural systems through the establishment of cooperatives and bare land, vegetation areas have been converted into cultivated lands. the human population of the study area was increased dramatically in the study period. on the other hand, ecosystems like forest and plantation forest, water body, riverine vegetation showed negative increment. the greater percentage increase of population number over cultivated, forest, shrub and grazing lands showed that population growth is a major driving force for these changes. in this case, the high population growth increased demand for agricultural products and result the expansion of cultivated land at the expense other ecosystem types. in line with this, a study by tsegaye, et al. [22] describe demographic factors related to population growth as among the primary causes for lulc changes in ethiopia. the results from natural forest analysis show that within 12 years from 1972-1984 a loss of 4532 hectare was recorded which is severe destruction in-terms of forest ecosystem. and from 1984-1992 364 hectares was reduced which shows continuing deforestation of forests, again from 1992-2001 a reduction of 466 ha was observed. and again from 2001-2012 of 34 ha was reduced, and from 2012-2019 a reduction of 41 hectares is recorded. as reported from the key informants it is obvious that the most important factor in the destruction of forests is the human activities for housing construction and wood for charcoal. both natural and plantation forests amongst other ecosystems have been degraded during the last 5 decades continuously. the following drivers or factors are the main causes for such degradation: changing of land use from forest into pasture, agriculture and urban, as a result of population growth and general land scarcity, use of the wood as a source of heat and energy in economically poor area and increase in fuel consumption. the plantation forest result show there was a reduction of 964 ha between 1972–1984, and continually it shows continuous reduction from 1984-1992 reduced by 589 ha,1992-2001 educed by 131,2001-2012 reduced by 106 ha. but from 2012-2019 it shows an increase of 205 ha (70%). this is due to afforestation programme. the plantations were established through government and international aid programs following the increased demand in construction and fuel woods [23]. the 2007 population and housing census results show that the population of ethiopia grew at an average annual rate of 2.6 percent between 1994 and 2007 and the annual rates of population growth for tigray regions is also almost the same as the national rate [14]. similarities the study area is one of the highly populated of tigray region. the population growth demanded more land for cultivation, more trees for domestic fuelwood consumption and more area for settlement. the population growth led to increased consumption of ecosystem services that affected the supply. the population dynamics are so far, important drivers affecting both demand and supply of ecosystem services in mekelle city region. due to the city’s rapid urbanization the surrounding forests are cut down annually mainly for the purpose of extracting charcoal, fire wood, for the construction of residential area and roads as well as expansion of farm lands in the surrounding areas [24]. the water body showed continuously declining of 1368 ha between 1974 and 1984, a dramatic decrease of 12185 between 1984-1992, from 1992-2001 a decrease of 817, from 2001-2012 a reduction of 1077 ha and from 2012-2019 a positive increase of 133 ha was observed due to construction different types of water structure of dams and ponds. despite, the recent increment of water body due to construction of water structure like dams and ponds this study found that the water body was affected several times by recurrent drought of climate changes. particularly during the 1985 there was heavy drought in northern ethiopia in tigray and wollo. the lulc change results show that the periods between 1984-1992 there was severe damage and reduction of ecosystem in water body, natural and plantation forest, bushes and shrubs, river side vegetation and grass lands. there was severe drought that costs the lives of mankind. due to the serious drought in 1985, the farmland was intensively used for cultivation, as the quality of the land had shown deterioration in quality and as some of the residents were come from other parts of tigray and settled in the study area. to substantiate the ecosystem reduction, the climate variability trend analysis obtained from historical metrological data was validated by local elderly persons perceptions. the majority of the respondents ranked climate related factors as the first order driver. their perception about rainfall is in agreement with the meteorological data analysis. the droughts have negatively impacted the ecosystem causing further degradation, as people sought alternative means of survival such as cutting of trees to prepare charcoal. further, the variation in inter-annual rainfall amount causes differences in vegetation. in semi-arid highlands of northern ethiopia, incidents of droughts of varying severity and duration occur. the occurrence of these droughts is associated mainly with the seasonal rainfall variability for the period 1954-2008 and the study shows that the northern part of ethiopia is warming faster than the national average of 0.25ºc per decade [25]. asian review of environmental and earth sciences, 2021, 8(1): 18-29 28 © 2021 by the authors; licensee asian online journal publishing group tigray experiences major environmental hazards of rainfall instabilities causing droughts and famine, earthquakes, invasions of locust swarms, and epidemics [26]. the cultivated land in mekelle city region expanded due to an increase the vulnerability of human environment system to climate fluctuation causes land degradation. in ethiopia, the driving forces, have adverse effects of loss of biodiversity and ecosystem service degradation [27].the rainfall in ethiopia is highly variable and unpredictable in time and space [28]. the study finds climate variability have affected various ecosystem particularly the water bodies in the last 47 years in the study area. the lulc changes and climatic change in combination with soil deterioration alter the hydrological cycle, thereby progressively degrading the ecosystem and reducing the quality of water ecosystem. changes in lulc of at catchment level modify the availability of water resources of a basin in complex ways [29]. this study shows land use dynamics at catchment scale can also affect not only water but also other types of the ecosystem services. the results from bushes and shrubs prove that between 1972–1984 an increase of 7966 ha was observed. despite this, in the period of 1984-1992 and 1992-2001 there was a reduction of 3590 ha and 3155 ha respectively. in between 2001-2012 and 2012-2019 there was an increase of 1578 ha and 2233 ha respectively. this is due to policy on environmental rehabilitation through integrated watershed management, and the associated implementation programs, has been the key driver behind the observed increasing trend. the numerical result from bare land indicates that a continuous reduction from of 1972–1984, 1984–1992, 1992-2001,2001-2012 and 2012–2019 it reduced by 11802 ha,9 ha,3839,30 and 1930 hectares respectively. this indicate bare lands are encroached by urbanization and currently there are 326 hectares of bare lands. though the ecosystem restoration is not fast the period 1992-2001 was a turning point for ecological restoration for river side vegetations and bare land significantly reduced. and the year 2001-2012 was a turning point for grass land, bushes and shrubs. however, it is very important to realize from 2012-2019 there is a hope for ecological restoration. the findings show that the need of social-ecological systems as complex adaptive systems for policy development. understanding the city region as socio-ecological system can have the opportunity to manage its resilience towards sustainability. the urban areas and neighbouring rural areas together have to sustain the energy, material and ecosystem services flows. focusing on the local scale of the city has its pitfalls, as it fails to take account of those cross-scaling feedbacks. this is because mekelle city is not self-sufficient in terms of the ecosystem services provision on which it depends on a scale that extends well beyond the urban administrative boundaries where local interventions take place. recognising the social and environmental challenges that cities need to deal with, long-term urban decision-making under climate change and resource scarcity is crucial to help understand the complexity of the interdependencies in ecological, social and economic systems across scales and time which could help forecast and avoid unintended effects. these resources range from basics such as water and food, to economic goods and information. cut off these supplies to the modern city of mekelle can negatively affect the total function of the city. hence, this study concluded complex adaptive system theory have a great contribution to understand the relationships between the mekelle city and its environs to achieve sustainable urbanization. 5. conclusion and recommendations this study analyzed land use dynamics and its driving forces using various sources of data. using a mixed methods approach helped to gain a wide perspective on the identified research problem. the change detection analysis showed that substantial land cover change that had occurred. significantly, the lulc features are dynamically transformed to another land uses due to anthropogonic requirement of the local people and climate variability. from this study it is inferred that there were significant changes in vegetations and water bodies. unfortunately, most of the lulc features are transformed to build-ups and settlements and other land uses without considering their negative impacts on ecosystems with increasing rate of vulnerability to environmental degradation. the significant changes in lulc have contributed to dwindling of numerous ecosystems. based on the analyses there is a very high confidence that population growth and climate variability in both urban and rural is a major driver of lulc change. the ecosystem services are experiencing continuous loss. this study also found that both factors are drivers for land use dynamics in mekelle city region. but they differ in their rank. to sustain the ecosystem which are vital for the benefit of the people and economic development of the study area, appropriate spatial planning policy should be issued. thus, understanding how lulc changes drivers affect ecosystem service is important to communicate with decision makers, ecologist and land planners to craft appropriate land management legal frameworks. this study can be useful for efficient watershed management since mekelle city depend on distant watershed ecosystem services. monitoring the negative consequences of lulc while sustaining the supply of essential ecosystem services is vital. therefore, there is a need to design and implement appropriate spatial planning policies in city region by decision makers. a determined and a renowned approach is required to sustain the continuum provision of ecosystem services. in this regards the following measures are suggested to ensure sustainable provision of ecosystem services and ensure sustainable landscape management in mekelle city region, the application of spatial planning strategies is vital. in this regard, it is suggested that:((1) continuous monitoring on land use dynamics and strengthening ecological restoration (2) adopting watershed-based approach to improve the quality and quantity of ecosystem services (3) launching regional green infrastructure plans and regional ecological networks (4) river side restoration (5) further deep investigations on assessing the major drivers of lulc changes (6) strengthening measures for the implementation of regional spatial planning (7) introducing regional metropolitan plan and (8) sectoral integration of watershed management in mekelle city region. references [1] j. wu, "landscape sustainability science: ecosystem services and human well-being in changing landscapes," landscape ecology, vol. 28, pp. 999-1023, 2013.available at: https://doi.org/10.1007/s10980-013-9894-9. [2] a. hermann, s. schleifer, and t. wrbka, "the concept of ecosystem services regarding landscape research: a review," living reviews in landscape research, vol. 5, pp. 1-37, 2011.available at: https://doi.org/10.12942/lrlr-2011-1. asian review of environmental and earth sciences, 2021, 8(1): 18-29 29 © 2021 by the authors; licensee asian online journal publishing group [3] m. l. martínez, o. pérez-maqueo, g. vázquez, g. castillo-campos, j. garcía-franco, k. mehltreter, and r. landgrave, "effects of land use change on biodiversity and ecosystem services in tropical montane cloud forests of mexico," forest ecology and management, vol. 258, pp. 1856-1863, 2009.available at: https://doi.org/10.1016/j.foreco.2009.02.023. [4] m. s. i. sohel, s. a. mukul, and b. burkhard, "landscape׳ s capacities to supply ecosystem services in bangladesh: a mapping assessment for lawachara national park," ecosystem services, vol. 12, pp. 128-135, 2015.available at: https://doi.org/10.1016/j.ecoser.2014.11.015. [5] m. bürgi, a. m. hersperger, and n. schneeberger, "driving forces of landscape change-current and new directions," landscape ecology, vol. 19, pp. 857-868, 2005.available at: https://doi.org/10.1007/s10980-005-0245-3. [6] k. g. turner, s. anderson, m. gonzales-chang, r. costanza, s. courville, t. dalgaard, and l. porfirio, "a review of methods, data, and models to assess changes in the value of ecosystem services from land degradation and restoration," ecological modelling, vol. 319, pp. 190-207, 2016.available at: https://doi.org/10.1016/j.ecolmodel.2015.07.017. [7] j. kleemann, g. baysal, h. n. bulley, and c. fürst, "assessing driving forces of land use and land cover change by a mixed-method approach in north-eastern ghana, west africa," journal of environmental management, vol. 196, pp. 411-442, 2017.available at: https://doi.org/10.1016/j.jenvman.2017.01.053. [8] v. h. dale, s. brown, r. haeuber, n. hobbs, n. huntly, r. naiman, and t. valone, "ecological principles and guidelines for managing the use of land sup> 1," ecological applications, vol. 10, pp. 639-670, 2000.available at: https://doi.org/10.2307/2641032. [9] t. g. a. a. v. d. veen, "the effect of enclosures in rehabilitating degraded vegetation: a case of enderta district, northern ethiopia forest research," forest research, vol. 3, pp. 1-7, 2014. [10] a. g. abreha, "hydrogeochemical and water quality investigation on irrigation and drinking water supplies in the mekelle region, northern ethiopia," master's thesis, university of twente, 2014. [11] tcsa, "tigray population data demography," ed ethiopia: tigray stastical agency, 2019, pp. 1-70. [12] csa, the 1984 population census of ethiopia. results for addis ababa. addis ababa: central statistical authority, 1985. [13] g. m. foody, "status of land cover classification accuracy assessment," remote sensing of environment, vol. 80, pp. 185-201, 2002.available at: https://doi.org/10.1016/s0034-4257(01)00295-4. [14] y. a. m. gebremicael, p. van der zaag, and e. y. hagos, "quantifying longitudinal land use change from land degradation to rehabilitation in the headwaters of tekeze-atbara basin," ed ethiopia: elsevier, 2017, pp. 1581-1589. [15] t. gebreyohannes, f. de smedt, k. walraevens, s. gebresilassie, a. hussien, m. hagos, and k. gebrehiwot, "application of a spatially distributed water balance model for assessing surface water and groundwater resources in the geba basin, tigray, ethiopia," journal of hydrology, vol. 499, pp. 110-123, 2013.available at: https://doi.org/10.1016/j.jhydrol.2013.06.026. [16] e. teferi, w. bewket, s. uhlenbrook, and j. wenninger, "understanding recent land use and land cover dynamics in the source region of the upper blue nile, ethiopia: spatially explicit statistical modeling of systematic transitions," agriculture, ecosystems & environment, vol. 165, pp. 98-117, 2013.available at: https://doi.org/10.1016/j.agee.2012.11.007. [17] a. z. abraha, "assessment of spatial and temporal variability of river discharge, sediment yield and sediment-fixed nutrient export in geba river catchment, northern ethiopia," katholieke universiteit leuven, faculty of sciences, belgium2009. [18] m. millennium ecosystem assessment, ecosystems and human well-being. island press washington, dc, 2005. [19] e. ostrom, "a general framework for analyzing sustainability of social-ecological systems," science, vol. 325, pp. 419-422, 2009.available at: https://doi.org/10.1126/science.1172133. [20] d. j. campbell, d. p. lusch, t. a. smucker, and e. e. wangui, "multiple methods in the study of driving forces of land use and land cover change: a case study of se kajiado district, kenya," human ecology, vol. 33, pp. 763-794, 2005.available at: https://doi.org/10.1007/s10745-005-8210-y. [21] q. weng, remote sensing and gis integration: theories, methods, and applications. new york: mcgraw-hill, 2010. [22] d. tsegaye, s. r. moe, p. vedeld, and e. aynekulu, "land-use/cover dynamics in northern afar rangelands, ethiopia," agriculture, ecosystems & environment, vol. 139, pp. 174-180, 2010.available at: https://doi.org/10.1016/j.agee.2010.07.017. [23] t. abate and a. angassa, "conversion of savanna rangelands to bush dominated landscape in borana, southern ethiopia," ecological processes, vol. 5, pp. 1-18, 2016.available at: https://doi.org/10.1186/s13717-016-0049-1. [24] k. moges, "people’s awareness and perception level on the risks of climate change and constraints of their adaptation strategies in mekelle city, tigray regional state, ethiopia," civil and environmental research, vol. 8, pp. 1-17, 2016. [25] t. gebrehiwot and a. van der veen, "assessing the evidence of climate variability in the northern part of ethiopia," journal of development and agricultural economics, vol. 5, pp. 104-119, 2013.available at: https://doi.org/10.5897/jdae12.056. [26] k. a. bard, m. coltorti, m. c. diblasi, f. dramis, and r. fattovich, "the environmental history of tigray (northern ethiopia) in the middle and late holocene: a preliminary outline," african archaeological review, vol. 17, pp. 65-86, 2000. [27] m. muke, "reported driving factors of land-use/cover changes and its mounting consequences in ethiopia: a review," african journal of environmental science and technology, vol. 13, pp. 273-280, 2019.available at: https://doi.org/10.5897/ajest2019.2680. [28] k. tesfagiorgis, t. gebreyohannes, f. de smedt, j. moeyersons, m. hagos, j. nyssen, and j. deckers, "evaluation of groundwater resources in the geba basin, ethiopia," bulletin of engineering geology and the environment, vol. 70, pp. 461-466, 2011.available at: https://doi.org/10.1007/s10064-010-0338-3. [29] y. b. liu, f. de smedt, l. hoffmann, and l. pfister, "assessing land use impacts on flood processes in complex terrain by using gis and modeling approach," environmental modeling & assessment, vol. 9, pp. 227-235, 2005.available at: https://doi.org/10.1007/s10666-005-0306-7. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences vol. 4, no. 1, 46-57, 2017 issn (e) 2313-8173 / issn (p)2518-0134 doi: 10.20448/journal.506.2017.41.46.57 46 characteristics and productivity of the sediments and volcanic rocks aquifers in sunuta sub-basin, northeast ethiopia gobeze begashaw1 tafesse nt2  ( corresponding author) 1amhara design and supervision works enterprise 2department of geology, university of botswana, botswana. abstract sunuta sub-basin is found within the lower awash basin, northeast ethiopia, having an area of 1490.5km2. the objective of the research was to characterize the different sediments and volcanic rocks aquifers and evaluate their respective productivity. to achieve these objectives, primary and secondary data were collected. primary data such as geological, geological structures, and 82 water levels were collected during field investigation. 35 constant pumping test and 33 borehole log data were collected as secondary data from water offices in the area. with the exception of specific capacity, all other hydraulic properties were determined from recovery test data using theis and neuman analysis methods. specific capacity was determined from constant discharge test data. the mesozoic sandstone, tertiary and quaternary volcanic rocks and recent sediments are the main geological formations of the sub-basin. the aquifer types around the escarpments are unconfined whereas in the rift floor the aquifers are confined and semi-confined. in the rift floor the sediment thickness varies from 166-200m and also found interlayered with volcanic rock of rhyolite and basalt, forming multilayer confined and semi-confined aquifer. the general groundwater flow direction is from west to east. the different geological formations that are found constituting the area are categorized hydrogeologically into aquifer with intergranular weathered and fracture porosity and permeability, extensive aquifer with intergranular porosity and permeability and aquifer with fracture porosity and permeability. analysis of pumping test data revealed that hydraulic conductivity ranges from 0.268 to 31.1 m/day and transmissivity ranges from 9.6 to 2420 m²/day with mean values of 9.55 m/day and 632.79 m²/day, respectively. specific capacity ranges from 0.07 to 65.31 l/sec/m with mean values of 5.45 l/sec/m. on the basis of their corresponding transmissivity and specific capacity value, the different aquifers of the studied area were categorized into three aquifer potentiality groups: low, moderate and high potentiality aquifer. any future development of groundwater should be focused on the moderate and high potentiality aquifers. keywords: afar depression, aquifer types, groundwater productivity, hydraulic properties, tertiary volcanics. citation | gobeze begashaw; nata t. tafesse (2017). characteristics and productivity of the sediments and volcanic rocks aquifers in sunuta subbasin, northeast ethiopia. asian review of environmental and earth sciences, 4(1): 46-57. history: received: 4 october 2017 revised: 6 december 2017 accepted: 11 december 2017 published: 14 december 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: both authors contributed to the conception and design of the study. funding: the authors duly acknowledge amhara design and supervision works enterprise for sponsoring this research work and providing the necessary data. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ........................................................................................................................................................................................................... 47 2. methodology .......................................................................................................................................................................................................... 48 3. results and discussions ....................................................................................................................................................................................... 49 4. conclusions ............................................................................................................................................................................................................ 57 references ................................................................................................................................................................................................................... 57 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=gobeze begashaw https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=gobeze begashaw https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=gobeze begashaw https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt https://orcid.org/orcid-search/quick-search?searchquery=gobeze begashaw https://orcid.org/orcid-search/quick-search?searchquery=tafesse nt asian review of environmental and earth sciences, 2017, 4(1): 46-57 47 1. introduction 1.1. background groundwater is the second largest available reservoir of fresh water [1]. worldwide, more than 2 billion people depend on groundwater for their daily supply. a large proportion of the world’s agriculture and irrigation is dependent on groundwater, as are a large number of industries. whether groundwater or surface water is exploited for water supply is largely dependent on the location of aquifers relative to the point of demand [2]. in ethiopia also groundwater is the major fresh water resource currently used as source for water supply, irrigation and industries. the study area, sunuta sub-basin, is well known by uneven distribution of rainfall, scarcity of rainfall, scarce surface water and frequent occurrence of drought. most of the streams are intermittent. the communities’ economy mainly depends on livestock production and in some parts in agriculture. water problem is the main issue of the peoples living in this sub basin. this problem, even though, it has been there for long time at present it gets worst due to increased in the number residents, livestock’s numbers and agricultural activities in the sub-basin. currently the federal democratic republic of ethiopian ministry of agriculture is undertaking an extensive plan for irrigation in the awash basin (where the study area is located) of the afar national regional state in different zones using groundwater potential and surface waters to sustain food security of the region and for development of the country. among the areas selected by the ministry for groundwater-based irrigation development is the study area. the sustainability of this project is highly depending on the proper development, utilization and management of the groundwater of the area. proper and sustainable development of groundwater on the other hand depends on proper well site locations that are normally done based on the knowledge of the characteristics of the different aquifers and their respective productivity. such hydrogeological information’s are not available in the sunuta subbasin. this research that makes its objectives on characterization and productivity evaluation of the different aquifers is proposed to generate such kind of hydrogeological information’s that can be employed for better development of groundwater in the sub-basin. 1.2. description of the study area 1.2.1. location the study area is located in afar national regional state in zone 4 of ewaworeda and amhara national regional state in north wollo zone. it is found at about 490 km northeast of addis ababa. geographically, the sub-basin is located between the utm coordinates of 556695 to 650305 m e and 1292222 to 1335000 m n, having an area of about 1497.5 sq km and a perimeter of 245.9 km (figure 1). hydrologically, the sub-basin is located within the awash basin, an endorheic basin drain by a perennial river called awash that flows along the rift valley into the afar triangle. figure-1. location map of the study area. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. 1.2.2. phsiography and drainage pattern topographically, the sub-basin is ranging from steep slope to flat land. the elevation ranges from 3479m above sea level in the western side to 745m above sea level in the northeastern parts. asian review of environmental and earth sciences, 2017, 4(1): 46-57 48 the dominate topography in the sub-basin is plain and very gently sloping (0 – 4%) areas, which has an area coverage of 61% of the total study area. gently sloping (4 -8%) areas coverage is 22% of the total study area. areas that have a slope ranging from 8 to 30% and greater than 30% constituted 16% and 1% of the total study area, respectively. the elevation is decreasing from west to northeast sides of the sub-basin. the climate of the area is semi-arid to arid with no or occasional rainy season. it is drained by few perennial rivers such as chereti, sirinka, and uwa that rise from western and northwestern mountains (figure 2). among these only uwa is the only river that crosses the study area with high discharge during wet season and low discharge during dry season. the discharge from this river percolates into the thick sediments of sunuta plain in the eastern parts. besides to these perennial rivers, the sub-basin is also drained by intermittent streams that rise from the western, northwestern, southwestern and southern mountains. with the exception of the northeastern parts of the area, the general flow direction of the rivers is west to east. in the northeastern parts of the sub-basin, the flow direction of the rivers is northwest to southeast. generally the drainage pattern of the study area is dendritic (figure 2). 2. methodology different methods have been used to achieve the objectives of this research. delineation of the study area was done from available topo maps using different software’s, and then finalized by taking gps readings at different sites of the study area for ground checking. collections of pertinent documents, previously done regional and nationwide geological and hydrogeological maps, different studied documents around the study area, geological logs and pumping test data of the existing boreholes in the study area from different organizations were done. data for geology and hydrogeology were collected in the field with the help of gps. geological and structural investigations as a technique was conducted in the field paying particular attention to the different features of the overlying sediments and underlying volcanic rocks units for groundwater storage and transmission. landsat tm satellite image 15m resolution was used to locate and delineate large-scale tectonic structures, specially, faults and fracture systems of the study area with conjunctive use of the field investigation. these discontinuity features are extracted and digitized using arc gis10.1 software. figure-2. drainage map of the study area. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. inventory of groundwater structures (boreholes and hand dug wells) were conducted as part of the hydrogeological investigation. except the western area, most of the study area groundwater point elevation was obtained by surveyor’s level in order to have accurate well elevation. for determination of the hydraulic properties of the different aquifers 35 constant discharge and recovery pumping test data together with their corresponding geological and geophysical logs were used. the data were analyzed using aquifertest v.3.5 software. with the exception of specific capacity, all other hydraulic properties were determined from recovery test data using theis and neuman analysis methods. specific capacity was determined from constant discharge test data. to determine the different aquifer types and also to characterize the nature of each aquifer besides to the preparation of hydrogeological logs, plots of pumping test data on semi‐log scale (specialized plot) and log‐log scale (diagnostic plot) were prepared for different deep wells using microsoft office excel 2007 and the drawdown behavior were compared with the various theoretical models. theoretical models comprise the type of aquifer and initial and boundary conditions [3]. according to this author, specialized plots are specific to a given flow system. diagnostic plot allows the dominating flow regimes to be identified. asian review of environmental and earth sciences, 2017, 4(1): 46-57 49 3. results and discussions 3.1. geology 3.1.1. regional geology ethiopia can be divided in to four major physiographic regions, known as the western plateau, southeastern plateau, the main rift and the afar depression. the afar depression lies within the afro-arabian rift system. this rift system extends from syria in the north and passes through jordan valley, dead sea, red sea, afar depression, and east african rift and terminates in southern africa. the central part of the afar depression is dominated by lowland plains corrugated by horsts and grabens and rare local high relief peaks representing shield volcanoes. it can be divided into northern, east-central, southeastern, and southwestern regions on the basis of similar structural trends [4]. most of the sunuta sub-basin is included in the southwestern part of the afar depression in the south western region and partly it lies on the western escarpment (figure 3). the geological units of the afar depression and marginal areas can be divided into four broad groups: (1) neoproterozoic basement, mesozoic sedimentary rocks, and eocene– miocene basalts; (2) miocene igneous rocks (3) pliocene volcanic rocks (4) quaternary volcanic and sedimentary rocks. figure-3. geological map of the afar depression (after [5, 6]). source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. 3.1.2. local geology sandstone the sandstone is exposed in the western area in a locality west of alelesubula town 6 km at messala ridge (595760 e, 1305598 n, 1246m) (figure 5). the sandstone is existed underlying the ashange basalts along nnwsse trending normal faults and tilted along with the ashange basalts by about 350 towards nne. the upper part of the sandstone is red/pink in color, fine to coarse-grained and conglomeratic while the middle part is whitish and pebbly. petrographic studies by water works design and supervision enterprise [7] reported that the sandstone is medium to coarse grained, equigranular with clastic texture, and is composed of quartz (90%), opaque oxides (5%) and alkali feldspar (3%). individual grains are angular to sub-rounded and well sorted. quartz grains measure 0.5 mm on average but some are up to 2 mm long. small amounts of rock fragments are also present. the cement is brownish ferruginous material. basalts the western margin of the study area is covered by ashange and aiba basalt whereas the dahala basalt covers the eastern margin of the study area (figure 5). the ashange basalt is exposed in the western escarpment at hamaro, humo, sirinka, dehawodih, and merto area chains of ridges that extend north-south direction in the western parts of the study area. it is characterized by thinner individual lava flow thickness of about 5 meters and more alkaline affinity (figure 4). this unit is highly weathered with alteration minerals filling in the vesicles forming amygdales. the individual flows of this unit are known to be continuous only for few kilometers along strike. asian review of environmental and earth sciences, 2017, 4(1): 46-57 50 figure-4.a) contact between different flows of ashange basalt: on the top part moderately weathered and fractured and the lower part is deeply weathered. b) contact between aiba basalt without secondary material and the lower one is ashange basalt with secondary material filling and the red color line with small thickness 0.3 m indicates paliosoil. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. granites this rock type is found in the form of dykes in the western parts of the study area (figure 5). it is well exposed in sirinka and amaro area. the sirinka granite, which has grey color, is the longest one extended from sirinka to alwuha away from the study area cutting the ashange basalt with strike of 250ne. the granite has a grey and pink to red color, scarcely fractured in the top part whereas with depth it has a massive nature. petrographic studies by water works design and supervision enterprise [7] reported that the granite is holocrystalline, coarse grained and inequigranular/moderately porphyritic (20%) and partly glomeroporphyritic. phenocrystminerals are dominated by quartz (70%) and include alkali feldspar (sanidine) (~30%). quartz is subhedral to anhedral and measures up to 5 mm long. alkali feldspar, which is also euhedral to subhedral, has tabular habit and measures up to 1.5 mm long. the remaining smaller-sized minerals are constituted of equal proportions of quartz, sodic plagioclase, sanidine, myrmekite and small amounts of opaque oxides. mabla rhyolite the mabalaryolite is found in the western and northeastern parts of the study area forming isolated hills and ridges (figure 5). in the western parts the unit is highly affected by nnw-sse trending faults and also tilted eastward. petrographic studies by water works design and supervision enterprise (2011) reported that the rhyolite has vitrophyritic texture, and is composed of micrroclitic volcanic glass (~70%), rock fragment (~22%), quartz (~6%) and fine –anhedral opaque fe-oxide (~2%). the groundmass is composed of volcanic glass and rock fragments that consist of rhyolite and pumice. fluvio-lacustrine sediments these are found covering the plain areas in the western (sirinka plain and woydo plain) and eastern (sunuta plain) parts of the study area (figure 5). recent sediments are also found having limited areal extent along the river courses in the different parts of the study area. because of high elevation and slope variation between the eastern and western parts of the study area, erosion, transportation and denudation created on the western parts favors for the eastern parts of the study area to become depositional area. the sediments don’t have uniformity in terms of grain size and thickness throughout the area where they are found. they area consist of clay, silt, sand and gravel. in the eastern parts (sunuta plain) the thickness of the sediments varies from 166 – 200m whereas in the western parts it varies from 18 – 50 m. the sediments are also found interlayering with basalt. 3.1.3. geological structures generally in the study area, there are two related structural features; the afar depression and the western escarpment that formed by down-warping and subsequent faulting and rift ward tilting of fault blocks. the major structures are fractures, joints, lineaments and faults. the length of fractures, lineaments and faults varies from 2-6 km with different trends. their major trends of these structures are n-s, e-w, nw-se and ne-sw. the dominant trend in the western parts (around sirinka) of the study area is nnw-sse direction. asian review of environmental and earth sciences, 2017, 4(1): 46-57 51 figure-5. geological map of the study area and cross-section from a to b. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. 3.2. hydrogeology 3.2.1. general the saturated aquifer thickness of the sub-basin depended on the existence or not of the interlayered and underlying weathered and fractured volcanic rocks and the nature of the sediments. the interlayered and/or underlying volcanic rocks have variable weathered and fractured zones thickness, which is also serving as an aquifer. in the sub-basin the water level ranges from 2.65 m to 79.54 m with a mean of 54.89 m. the deeper water level is found in the eastern parts (sunuta plain) whereas in the western parts the water level is not deep. in the study area most of the drilled boreholes show that water table greater than 40m depth. 3.2.2. aquifer types interpreting a pumping test is primarily a matter of identifying an unknown system. system identification relies on models, the characteristics of which are assumed to represent the characteristics of the real aquifer system. theoretical models comprise the type of aquifer (figure 6), and initial and boundary conditions. in a pumping test, the type of aquifer and the inner and outer boundary conditions dominate at different times during the test. they affect the drawdown behavior of the system in their own individual ways. therefore,to identify an aquifer system, one must compare its drawdown behavior with that of the various theoretical models. the model that compares best with the real system is then selected for the calculation of the hydraulic characteristics. system identification includes the construction of diagnostic plots and specialized plots. diagnostic plots are log-log plots of the asian review of environmental and earth sciences, 2017, 4(1): 46-57 52 drawdown versus the time since pumping started. specialized plots are semi-log plots of drawdown versus time, or drawdown versus distance to the well; they are specific to a given flow regime. a diagnostic plot allows the dominating flow regimes to be identified; these yield straight lines on specialized plots. the characteristic shapes of the curves can help in selecting the appropriate model. the choice of theoretical model is a crucial step in the interpretation of pumping tests. if the wrong model is chosen, the hydraulic characteristics calculated for the real aquifer will not be correct [3]. depending up on this theoretical log-log and semi-log plots models, the actual pumping test executed have been plotted using microsoft excel in log-log and semi-log form to compare with the theoretical and also with conjunctive use of the actual field data of the geological and hydrogeological log data. the aquifer is categorized based on these theoretical curves as confined, unconfined and semi-confined aquifer (figures 7 9). because of different reasons the pumping test data does not exactly fit with theoretical curves, careful analysis were made to distinguish the layers from the hydrogeological log data. the alluvial aquifer has thick clay, silt, sand and gravel on the top part and the underlain material is fractured basaltic rocks and beneath this rock unit is massive basalts. figure-6. log-log and semi-log plots of the theoretical drawdown. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. figure-7. log –log plots of badule water supply well showing unconfined aquifer. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. asian review of environmental and earth sciences, 2017, 4(1): 46-57 53 figure-8. semi-log plots of sw17 water supply well showing semi-confined aquifer nature. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. figure-9. semi log time-drawdown plot of hd2 irrigation well show confined aquifer nature in afar sunuta plain. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. 3.2.3. aquifer characterization the study area is characterized by highly rugged topography in the western area, which is dominantly covered by volcanic rocks, and the low land, which is plain area covered by unconsolidated sediments and volcanic rocks. unconsolidated sediments underlying by the volcanic rocks of different types are found covering 60 percent of the total study area whereas volcanic rocks of different types are found exposed on the surface on the remaining 40 percent of the total area. this lithological variation favors the study area to have multi later aquifer system which asian review of environmental and earth sciences, 2017, 4(1): 46-57 54 is sediment-volcanicsediment-volcanic types of aquifer system mainly observed in the low land area in the eastern parts. the western parts of the study area also have alluvial sediments in sirinka, and woydo area underlying by basaltic rock, which is the major water bearing formation in this part of the sub-basin. based on such occurrences, hydrogeologically these geological formations are categorized into three medium: aquifer with intergranular weathered and fracture porosity and permeability, extensive aquifer with intergranular porosity and permeability and aquifer with fracture porosity and permeability. aquifer with intergranular weathered and fracture porosity and permeability (high productivity) unconsolidated sediments and the underlying volcanic rocks constitute such aquifers that are characterized by the presence of both intergranular and fracture porosity and permeability (figure 10). aquifers of this type are found in northern, northeastern, eastern and central parts of the sub basin (figure 12). the aquifers are mainly unconfined and confined types. figure-10. hydrogeological log of hd2 irrigation well with high productivity of quaternary basaltic aquifer. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. extensive aquifer with intergranular porosity and permeability (high to very high productivity) this is a porous medium constituted mainly by unconsolidated sediments of different types. it is found in limited area coverage in the western parts whereas in the central, eastern, northern and southern parts it is found covering extensive areas. geological logs data obtained from deep wells drilled in the different parts of the eastern and central parts of the sub-basin (sw14, sw19, sw20, sw21, sw23, sw26, sw32, sw33 and sw35) revealed that the thickness of the fluvo-lacustrine sediments ranges from 166m to 200m. the discharge of these wells ranges from 28l/s to 62 l/s with an average discharge of 49.5l/s. the maximum recorded drawdown with a pumping rate of 38l/s for 24hrs is 63.35m. the sediments are found underlined by volcanic rocks of different types. moreover this area has also sediments interbedded with volcanic rocks of different types (figure 11). aquifer with fracture porosity and permeability this is a fracture medium constituted mainly by fractured volcanic rocks of different types. it is found mainly in the western parts of the sub basin (figure 12) that are characterized by rugged topography. since the area is water contributing area to the central and eastern low land areas of the sub basin, the aquifers are low yield aquifers. asian review of environmental and earth sciences, 2017, 4(1): 46-57 55 3.2.4. aquifer productivity the basic aquifer properties that were considered for evaluating the aquifer potentiality are transmissivity (t), hydraulic conductivity (k) and specific capacity. the pumping test data of 35 deep wells were analyzed and the results are summarized and given in table 1. the computed values of hydraulic conductivity ranges from 0.268 – 31.1 m/day with mean value of 9.55 m/day. the lowest one found in the western parts of the study area whereas the highest is found in the eastern parts. the average hydraulic conductivity of the aquifers of unconsolidated sediments by taking 8 irrigation wells is 8.2 m/day. the result of the analysis also reveal that transmissivity ranges from 9.6 to 2420 m2/day and specific capacity ranges from 0.07 to 65.31 l/sec/m with mean values of 632.79 m2/day and 5.45 l/sec/m, respectively. figure-11. hydrogeological log of sw14, sw33 and sw35 drilled in sediments interbedded with volcanic rocks. source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. asian review of environmental and earth sciences, 2017, 4(1): 46-57 56 table-1.computed hydraulic properties of aquifers. no. well d x y depth (m) q (l/s) s q/sw t k 1 gbh-2 563729 1301682 151 2.1 32.07 0.07 9.6 0.268 2 swtw1 566480 1299859 240 19.53 70.97 0.28 96.7 1.4 3 badule#2 607012 1310055 286.5 28 12.57 2.23 507 7.78 4 merto 627929 1308203 179 22.5 7.39 3.04 245 3.41 5 sunuta#2 630875 1305530 225 53 10.16 5.22 1010 14 6 sunuta#6 629928 1304713 216 55 6.18 8.90 1220 20.1 7 hd2 628093 1323022 203 80 14.93 5.36 506 12.6 8 sw 07 629196 1305200 204 64 0.98 65.31 517 7.8 9 sw 10 628394 1306098 202 60 3.5 17.14 2420 31.1 10 sw12 629484 1305759 202 75 25.32 2.96 644 17 11 sw 13 628801 1306978 193 62 4.3 14.42 1970 26.6 12 sw14 630033 1306230 228 80 12.93 5.41 519 7.21 13 sw 15 629348 1307106 200 53 38.63 1.37 56.4 1.34 14 sw 16 629209 1307721 168 55.5 57.34 0.97 934 19.4 15 sw 17 628670 1307551 138 53 40.98 1.29 336 5.09 16 sw 19 629083 1308282 218 55.5 59.86 0.93 341 4.74 17 sw 20 628952 1308892 200 50 63.35 0.79 38.6 0.68 18 sw 21 628276 1309272 176 55.5 25.5 2.18 224 3.74 19 sw22 628391 1308445 124 55 64 0.86 513 12.2 20 sw 23 628542 1308130 212 53 74.9 0.71 222 2.64 21 sw 24 629668 1308794 200 52 73.57 0.71 151 2.29 22 sw 25 628808 1309507 203 58 241 4.01 23 sw26 628590 1309855 214 62 14.39 4.31 771 8.56 24 sw27 628471 1310444 202 73 8 9.13 1520 21 25 sw 32 625457 1305814 174 48 14.34 3.35 931 12.9 26 sw33 625468 1305024 180 28 6.14 4.56 906 18.9 27 sw 35 625813 1304050 235 56 12.21 4.59 744 10.7 28 sw 41 625022 1307597 238 50 23.89 2.09 538 6.4 29 sw 43 625793 1310860 216 50 27.05 1.85 980 16.3 30 sw 44 625744 1311458 240 46 48.24 0.95 323 3.59 31 sw 45 625646 1312069 246 46 40.37 1.14 249 2.76 32 sw 46 625615 1312667 248 24 40.94 0.59 300 3.34 33 sw 49 621674 1309303 246 30 68.35 0.44 131 1.46 34 sw 50 621759 1308681 246 50.6 4.49 11.27 1943 21.6 35 sw 53 622123 1307034 240 40 48.72 0.82 90.3 1.25 source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. in this research, based on the analyzed result of transmissivity and specific capacity, an attempt was made to classify the aquifers of the study area into different class of potentiality. this classification was made on the basis of sen [8] scheme. accordingly, the unconsolidated sediments and volcanic rocks of the study area are grouped into three-aquifer group. these are: 1. low potential aquifer (tertiary volcanics and overlaying sediment); 2. moderate potential aquifer (alluvial and fluvo-lacustrine sediments with underlying volcanic rocks); and, 3. highly potential aquifers (fluvo-lacustrine sediments and underlying basalts and rhyolites). low potential aquifer low potential aquifer is mainly found in the western part of the study area (figure 12). as it was observed during field survey, tertiary ashange basalt fractures are filled by secondary minerals such as calcite and zeolites which decrease the permeability and porosity. the overlying alluvium is also dominated by silt and clay. the computed hydraulic conductivity and transmissivity for the borehole drilled in this aquifer is 0.27 m/day and 11.7 m2/day. a continuous pumping test was conducted for 1440 minute with a discharge of 2.1l/s and the maximum drawdown recorded was 32.07 m. the swl is 44.66m and the depth of the borehole is 151 m. moderate potential aquifer (alluvial and fluvolacustrine sediments with underlying volcanic rocks) this aquifer is located in the western parts adjacent to the rivers and also in the eastern parts occupying topographically low land areas (figure 12). transmissivity values computed from pumping test data of the deep wells that were drilled in this aquifer in the eastern parts of the sub-basin ranges from 50-500 m2/day, indicating the moderate potential aquifer. in the western parts computed transmissivity and hydraulic conductivity (table 1) from pumping test data of the deep wells that is drilled in this aquifer also reveal moderate potentiality nature of this aquifer. high potential aquifers (fluvo-lacustrine sediments and underlying basalts and rhyolites) this aquifer types is found in the eastern and northeastern parts of the sub-basin (mainly in the afar depression, figure 12) forming multilayer aquifer system. deep wells that have a depth ranging from 124 to 286.5m were found drilled in this area for domestic and irrigation purposes. the discharges of the wells range from 22l/s (for water supply wells) to 80l/s for (irrigation wells). the lithological logs of these wells show that the thickness of the sediment ranges from 166 to 200 m with the interlayered weathered-fractured basalt and rhyolite. transmissivity values these multilayer aquifers computed from pumping test data of the deep wells ranging from 500 to 2420 m2/day. asian review of environmental and earth sciences, 2017, 4(1): 46-57 57 figure-12. hydrogeological map of the study area source: gobeze begashaw, m.sc. thesis, university of mekelle, mekelle, ethiopia, 2016. 4. conclusions the different geological formations that are found constituting the area are categorized hydrogeologically into aquifer with intergranular weathered and fracture porosity and permeability, extensive aquifer with intergranular porosity and permeability and aquifer with fracture porosity and permeability.confined, unconfined, and semiconfined aquifer types, which exist as multilayer aquifer system, are the major aquifer types that were identified in the area. analysis of pumping test data revealed that hydraulic conductivity ranges from 0.268 to 31.1 m/day and transmissivity ranges from 9.6 to 2420 m²/day with mean values of 9.55 m/day and 632.79 m²/day, respectively. this variation of both hydraulic conductivity and transmissivity is a result of differences in intensity of weathering, degree of fracturing and interconnectivity nature of fractures in the volcanic rock units. specific capacity ranges from 0.07 to 65.31 l/sec/m with mean values of 5.45 l/sec/m. on the basis of their corresponding transmissivity and specific capacity value, the different aquifers of the studied area were categorized into three aquifer potentiality groups: low, moderate and high potentiality aquifer. any future development of groundwater should be focused on the moderate and high potentiality aquifers. references [1] p. h. gleick, "water resources" in encyclopedia of climate and weather, ed. by. s. h. schneider vol. 2. new york: oxford university press, 1996. [2] k. m. hiscock, hydrogeology principles and practice. united kingdom: school of environmental sciences university of east anglia, 2005. [3] g. p. kruseman, analysis and evaluation of pumping test data, 2nd ed. wageningen, the netherlands: international institute for land reclamation and improvement, 1990. [4] b. alebachew and a. g. mohamed, tectonics of the afar depression: a review and synthesis. richardson, tx 75083-0688, usa: department of geosciences, the university of texas at dallas, 2005. [5] j. varet, geology of central and southern afar (ethiopia and djibouti republic) f. gasse for chapter iv on sedimentary formation, eds . paris: cnrs, france, 1978. [6] g. d. acton, s. stein, and j. f. englen, "block rotation and continental extension in afar: a comparison to oceanic microplate systems," tectonics, vol. 10, pp. 501–526, 1991. view at google scholar | view at publisher [7] water works design and supervision enterprise, "teru area groundwater potential assessment project," draft phase i geology report, addis ababa, 2011. [8] z. sen, applied hydrogeology for scientists and engineers. london: crs press, lewis publishers, 1995. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=block%20rotation%20and%20continental%20extension%20in%20afar:%20a%20comparison%20to%20oceanic%20microplate%20systems http://dx.doi.org/10.1029/90tc01792 72 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 72-78, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.72.78 © 2020 by the authors; licensee asian online journal publishing group spatial analysis of water quality in parts of rivers niger and kaduna catchments, north central, nigeria idris, aliyu ja’agi1 yahaya, t. i.2 abubakar, a. s.3 jigam, a. a.4 ( corresponding author) 1,2,3department of geography, federal university of technology minna, niger state, nigeria. 4department of biochemistry, federal university of technology minna, niger state, nigeria. abstract it is understood that human activities have continue to alter the physico-chemical patterns of water and it’s resources, which has resulted into poor water quality in the study area. as comprehensive distribution of water quality parameters in the study area is of great interest, there exist a golden opportunity to consider a study with gis aided spatial coverage beyond laboratory analytical dimensions. thus, a total of thirty two (32) samples of water and sediment were collected during rainy and dry season for physico-chemical analysis. water samples collected were analysed in situ for seven (7) parameters using hanna multiparameter analyser and eight (8) other parameters were analysed in the analytical laboratory following standard methods. the finding revealed a significant number of parameters analysed were beyond regulatory limits. it is hence recommended that visible policies aimed at ensuring good water quality in the study area are critical for sustainability. keywords: physico-chemicals, sediments, water quality, health, environment, gis, rivers, spatial distribution. citation | idris, aliyu ja’agi; yahaya, t. i.; abubakar, a. s.; jigam, a. a. (2020). spatial analysis of water quality in parts of rivers niger and kaduna catchments, north central, nigeria. asian review of environmental and earth sciences, 7(1): 72-78. history: received: 7 july 2020 revised: 10 august 2020 accepted: 3 september 2020 published: 24 september 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 73 2. the study area ................................................................................................................................................................................. 73 3. material and methods ..................................................................................................................................................................... 73 4. results ................................................................................................................................................................................................ 74 5. conclusion ......................................................................................................................................................................................... 78 references .............................................................................................................................................................................................. 78 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.72.78&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/2175 https://orcid.org/0000-0002-7275-6523 https://orcid.org/0000-0002-0439-9130 https://orcid.org/0000-0002-3590-5075 https://orcid.org/0000-0001-6887-7456 asian review of environmental and earth sciences, 2020, 7(1): 72-78 73 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study has been able to demonstrate comprehensive gis aided spatial distribution of physic chemical characteristics of water and sediment with regard to water quality assessment which non known related past studies have done in the study area. 1. introduction it is a common knowledge that human activities continue to elicit widespread effect on the physical, chemical and biological processes within aquatic ecosystems [1, 2]. poor water quality in the study area can result into a serious threat to the existence of human and biodiversity at large. rivers niger and kaduna catchments are characterised by arable land where majority of its people practice farming [3]. this practice can eventually cause degradation of water quality and disproportionate effect on the socio-economic wellbeing of the communities in the area. spatial analyses are any types of data analyses that extract and/or produce spatial information based on operations on different layers of data. gis provides the organizational framework which allows numerical and statistical analyses to be easily applied on real-world data. the simple, but essential and fundamental ability to overlay a basically unlimited number of gis layers together with hundreds of tools (gis functions performing computations on spatial data) to be used for solving issues of spatial analysis and spatial statistics is what makes gis so different from using hardcopy maps. spatial analysis with gis has been used in many studies to demonstrates the breadth of its utility in the field of environmental sciences [4]. communities in the study area depend on these rivers for livelihood [5] and lack of comprehensive research information about the physico-chemical status of the rivers informed the need for immediate investigation in the area. also, as comprehensive distribution of water quality parameters in the study area is of great interest, there exist a golden opportunity to consider a study with spatial coverage beyond laboratory analytical dimensions. finding of this study will provide opportunity for researchers and relevant stakeholders to improve on future studies and overall environmental performance. 2. the study area the study area for the investigation is communities in parts of rivers niger and kaduna catchment areas, niger state which lies between longitude 3˚30'n and 7˚20'e and latitude 8˚22'n and 11˚30'n; located at the guinea savanah vegetation zone in the north central part of nigeria figure 1 [5]. the study area was divided into zones according to agroecological factors. along river niger, the upper zone is from rabba village in mokwa local government area (lga), middle zone is at muregi and the lower zone is after muregi in mokwa lga down to baro village in agaie lga. study area along river kaduna was divided into two zones. upper zone is from wuya village in lavun lga and the lower zone from half way down to muregi. the major economic activities of the communities living around the area are agriculture and fishing. these are the leading sector in terms of employment, income earning and overall contribution to the socio-economic wellbeing of the people. the kaduna and niger river flood plains are many kilometers wide at the downstream of nupe basement boundary, two major streams yanko ikko, dumi, ebigi. all these empty their waters in to niger river [5]. figure-1. map of the study area showing parts of rivers niger and kaduna catchment, north central, nigeria. 3. material and methods (a) sampling point’s identification water samples were collected from eight selected sampling points in the study area figure 2. the eight sampling points were based on altitude and information from the key stakeholders in the area. samples were collected using standard procedures for water sample collection and preservation. each sampling point were georeferenced using global position system (gps) device in longitude and latitude in degree, minutes and seconds (dms) format. asian review of environmental and earth sciences, 2020, 7(1): 72-78 74 © 2020 by the authors; licensee asian online journal publishing group figure-2. map of the study area showing study zones and the sample points. (b) water sampling and preservation a total of thirty two (32) samples of water and sediment were collected during rainy and dry season for physico-chemical analysis. water samples collected were analysed in situ for seven (7) parameters using hanna multiparameter analyser. the samples were preserved in ice flasks and transported immediately to the reference laboratory. upon arrival, water and sediment samples were extracted and analysed immediately for eight (8) other parameters following the method outlined by federation & american public health association fapha [6]. (c) spatial data analysis the gps location data earlier captured from the all sample points and the values for the physico-chemical parameters obtained from analytical processes were transferred into excel package of the microsoft office software, sorted and saved in tab delimited file format that is compactible in arcgis environment. arcmap was lunched and the prepared dataset was imported into the table of content in the gis interface using the tab delimited as file format, universal transverse mercator (utm) projection system was chosen and set to zone 32n. therefore, interpolation was done using the spatial analysis extension toolbox of the arcgis (version 10.5), the inverse distance weighted (idw) technique was chosen because it uses the measured values surrounding the prediction location to predict a value for any unsampled location, based on the assumption that things that are close to one another are more alike than those that are further apart. finally, at the tab of idw interface, the sample points were selected separately and imported, the output was saved and then ok for processing. the result maps were then exported in jpeg format after adding neat-line, grid, north arrow, scale and legend for presentation and discussion. 4. results 4.1. spatial distribution of physico-chemical characteristics of water samples during rainy season as revealed in figure 3, the value of ph ranges between 5.2 and 7.4, salinity ranges between 41psu and 81psu, temperature ranges between 22.1°c and 23.3°c, dissolved oxygen (do) ranges between 6.9mg/l and 8.6mg/l, conductivity ranges between 16μs/cm and 43μs/cm, total dissolved solids (tds) value ranges between 17.8ppm and 23.6mg/l, turbidity ranges between 47ntu and 96ntu, sulphate concentrations ranges between 0.72ppm and 1.95ppm, manganese (mn) ranges between 0.15ppm and 0.98ppm, chloride concentrations ranges between 18.51ppm and 78.79ppm. chemical oxygen demand (cod) ranges between 13.8ppm and 23.85ppm, biochemical oxygen demand (bod) ranges between 7.05ppm and 12.56ppm, total suspended solid (tss) ranges between 15.81ppm and 38.87ppm, total hardness (th) ranges between 3.32ppm and 7.65ppm and potassium ranges between 0.08ppm and 1.54ppm across the study area during rainy season. the ph, salinity, temperature, do, sulphate, chloride, th and potassium values obtained are all within nigeria regulatory limit. the values of tds, turbidity, mn, cod, bod, tss in the study area are largely above nigeria regulatory limits. the relatively high levels of a number of these parameters (which are largely higher than that of dry season) can be attributed to higher farming activities in rainy season, presence of decaying organic matter due to intense use of plant minerals and pesticides in the study area. these values are also indications of polluted water which are capable of increasing the concentrations of hazardous chemical (particularly from intense agrochemical use by farmers) in water in the study area. asian review of environmental and earth sciences, 2020, 7(1): 72-78 75 © 2020 by the authors; licensee asian online journal publishing group figure-3. interpolated distance weighted maps of (a) ph (b) salinity, (c) temperature, (d) do, (e) conductivity, (f) tds, (g) turbidity, (h) sulphate, (i) mn, (j) chloride, (k) cod, (l) bod, (m) tss, (n) th and (o) potassium of water samples during rainy season. 4.2. spatial distribution of physico-chemical characteristics of water samples during dry season as revealed in figure 4, the value of ph ranges between 5.4 and 6.9, salinity ranges between 28psu and 64psu, temperature ranges between 25.12°c and 28.1°c, dissolved oxygen (do) ranges between 5.3mg/l and 6.6mg/l, conductivity ranges between 10μs/cm and 30μs/cm, total dissolved solids (tds) value ranges between 6.7ppm and 20.1mg/l, turbidity ranges between 12.71ntu and 88ntu, sulphate concentrations ranges between 0.69ppm and 2.15ppm, manganese (mn) ranges between 0.08ppm and 1.06ppm, chloride concentrations ranges between 35.51ppm and 105.98ppm. chemical oxygen demand (cod) ranges between 24.81ppm and 44.99ppm, biochemical oxygen demand (bod) ranges between 9.82ppm and 18.1ppm, total suspended solid (tss) ranges between 30ppm and 53ppm, total hardness (th) ranges between 4.6ppm and 10.52ppm and potassium ranges between 0.13ppm and 2.07ppm across the study area. the values of tds, turbidity, mn, cod, bod, tss in the study area are largely above nigeria regulatory limits. the relatively high levels of a number of these parameters during dry season (although largely lower than that of rainy season) can also be attributed to the presence of decaying organic matter due to use of plant minerals and pesticides in the study area. these values are also indications of polluted water which are capable of increasing the concentrations of hazardous chemical (particularly from intense agrochemical use by farmers) in water in the study area. asian review of environmental and earth sciences, 2020, 7(1): 72-78 76 © 2020 by the authors; licensee asian online journal publishing group figure-4. interpolated distance weighted maps of (a) ph (b) salinity, (c) temperature, (d) do, (e) conductivity, (f) tds, (g) turbidity, (h) sulphate, (i) mn, (j) chloride, (k) cod, (l) bod, (m) tss, (n) th and (o) potassium of water samples of dry season. 4.3. spatial distribution of physico-chemical characteristics of sediment samples during rainy season as revealed in figure 5, the value of sulphate concentrations ranges between 4.61ppm and 8.62ppm, manganese (mn) ranges between 0.96ppm and 2.86ppm, chloride concentrations ranges between 5.13ppm and 32.65ppm. potassium ranges between 4.6ppm and 52.69ppm across the study area. the relatively high levels of a number of these parameters during rainy season can be attributed to the presence of decaying organic matter due to use of plant minerals and pesticides in the study area. these values are also indications of polluted water which are capable of increasing the concentrations of hazardous chemical (particularly from intense agrochemical use by farmers) in water in the study area. asian review of environmental and earth sciences, 2020, 7(1): 72-78 77 © 2020 by the authors; licensee asian online journal publishing group figure-5. interpolated distance weighted maps of (a) sulphate, (b) mn, (c) chloride, (d) potassium of sediment samples of rainy season. figure-6. interpolated distance weighted maps of (a) sulphate, (b) mn, (c) chloride, (d) potassium of sediment samples of dry season. asian review of environmental and earth sciences, 2020, 7(1): 72-78 78 © 2020 by the authors; licensee asian online journal publishing group 4.4. spatial distribution of physico-chemical characteristics of sediment samples during dry season as revealed in figure 6 the value of sulphate concentrations ranges between 5.28ppm and 22.08ppm, manganese (mn) ranges between 0.2ppm and 2.79ppm, chloride concentrations ranges between 22.78ppm and 72.41ppm. potassium ranges between 10.56ppm and 62.74ppm across the study area. the relatively high levels of a number of these parameters during dry season can be attributed to the absence of precipitation, presence of decaying organic matter due to use of plant minerals and pesticides in the study area. these values are also indications of polluted water which are capable of increasing the concentrations of hazardous chemical (particularly from intense agrochemical use by farmers) in water in the study area. 5. conclusion despite the fact that poor water quality has obviously lead and continue to elicit negative effects on human health and the general environment, little or no attention has been given by related studies to give the problem a befitting spatial coverage. hence, this study present a comprehensive gis aided spatial coverage of the physicochemical characteristics of water quality beyond laboratory analytical dimensions. in conclusion, this research has demonstrated the need for effective water quality research tools, government dedication, political wills, and collective responsibility of all stakeholders toward ensuring sustainability of water and it resources in the study area. it is therefore recommended that effective and laudable research tools of this kind be encouraged to guarantee cleaner and healthier water for all. references [1] a. gogoi, p. mazumder, v. k. tyagi, g. t. chaminda, a. k. an, and m. kumar, "occurrence and fate of emerging contaminants in water environment: a review," groundwater for sustainable development, vol. 6, pp. 169-180, 2018. [2] t. joko, s. anggoro, h. r. sunoko, and s. rachmawati, pesticides usage in the soil quality degradation potential in wanasari subdistrict. brebes. indonesia: applied and environmental soil science, 2017. [3] t. c. ogwueleka, "assessment of the water quality and identification of pollution sources of kaduna river in niger state (nigeria) using exploratory data analysis," water and environment journal, vol. 28, pp. 31-37, 2014. [4] k. c. clarke, j. m. johnson, and t. trainor, "contemporary american cartographic research: a review and prospective," cartography and geographic information science, vol. 46, pp. 196-209, 2019. [5] a. j. a. idris, t. i. yahaya, a. s. abubakar, and a. a. jigam, "pesticides and fertilizers use in parts of rivers niger and kaduna catchments, north central, nigeria," asian review of environmental and earth sciences vol. 7, pp. 18-25, 2020. [6] w. e. federation, american public health association. standard methods for the examination of water and wastewater. washington, dc, usa: american public health association, 2005. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. asian review of environmental and earth sciences vol. 4, no. 1, 12-19, 2017 issn(e) 2313-8173:/ issn(p) 2518-0134 doi: 10.20448/journal.506.2017.41.12.19 12 properties of concrete containing rubber aggregate derived from discarded tires nguyen duc luong1  hoang vinh long2 ngo kim tuan3 nguyen duy thai4 ( corresponding author) 1,2,3,4national university of civil engineering (nuce), hanoi, vietnam abstract this study carried out the experiment to evaluate the effects of different contents and sizes of rubber particles derived from discarded tires used for replacing fine and coarse natural aggregates, on the workability of fresh rubberized concrete and the compressive and flexural strengths of hardened rubberized concrete. the study results showed that the workability of fresh rubberized concrete was improved when replacing natural fine aggregate (sand) with fine rubber particles (2.5-5 mm) at the replacing proportions of 30-50% by volume, and when replacing natural coarse aggregate (crushed stone) with coarse rubber particles (5-20 mm) at the replacing proportions of 10-30% by volume. with respect to the mechanical properties of hardened rubberized concrete, a larger reduction in the compressive and flexural strengths was generally found when the replacing proportions increased and when coarse aggregate rather than fine aggregate was replaced by rubber particles at all replacing proportions (10-50%). however, the study results also indicated that using fine rubber particles for replacing fine natural aggregate at the low replacing proportion (up to 10%) might not cause the significant effect on the compressive and flexural strength of rubberized concrete. keywords: discarded tire rubber, fine and coarse rubber particle, rubberized concrete, workability, mechanical properties. citation | nguyen duc luong; hoang vinh long; ngo kim tuan; nguyen duy thai (2017). properties of concrete containing rubber aggregate derived from discarded tires. asian review of environmental and earth sciences, 4(1): 12-19. history: received: 3 july 2017 revised: 20 july 2017 accepted: 12 august 2017 published: 6 september 2017 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: this study is the major part of the research project “studying light concrete using rubber aggregate recycled from discarded tires”, b2015-03-16 (2015-2016). funding: the authors would like to thank the vietnam ministry of education and training that provided the financial support for conducting this project. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 13 2. experimental study ......................................................................................................................................................................... 14 3. results and discussions .................................................................................................................................................................. 15 4. conclusions ....................................................................................................................................................................................... 18 references .............................................................................................................................................................................................. 18 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://orcid.org/orcid-search/quick-search?searchquery=nguyen duc luong https://orcid.org/orcid-search/quick-search?searchquery=hoang vinh long https://orcid.org/orcid-search/quick-search?searchquery=ngo kim tuan https://orcid.org/orcid-search/quick-search?searchquery=nguyen duy thai https://orcid.org/orcid-search/quick-search?searchquery=nguyen duc luong https://orcid.org/orcid-search/quick-search?searchquery=hoang vinh long https://orcid.org/orcid-search/quick-search?searchquery=ngo kim tuan https://orcid.org/orcid-search/quick-search?searchquery=nguyen duy thai https://orcid.org/orcid-search/quick-search?searchquery=nguyen duc luong https://orcid.org/orcid-search/quick-search?searchquery=hoang vinh long https://orcid.org/orcid-search/quick-search?searchquery=ngo kim tuan https://orcid.org/orcid-search/quick-search?searchquery=nguyen duy thai https://orcid.org/orcid-search/quick-search?searchquery=nguyen duc luong https://orcid.org/orcid-search/quick-search?searchquery=hoang vinh long https://orcid.org/orcid-search/quick-search?searchquery=ngo kim tuan https://orcid.org/orcid-search/quick-search?searchquery=nguyen duy thai https://orcid.org/orcid-search/quick-search?searchquery=nguyen duc luong https://orcid.org/orcid-search/quick-search?searchquery=hoang vinh long https://orcid.org/orcid-search/quick-search?searchquery=ngo kim tuan https://orcid.org/orcid-search/quick-search?searchquery=nguyen duy thai asian review of environmental and earth sciences, 2017, 4(1): 12-19 13 1. introduction it has been estimated that 1000 million tires reach the end of their useful life every year. by the year 2030, the number can reach up to 1200 million tires representing almost 5000 million tires (including stock piled) to be discarded on a regular basis [1]. the development and enforcement of regulations and guidance on collection, storage and separation, transport, processing, disposal, and recycling activities for discarded tires in several countries such as usa, japan, korea, and taiwan has brought a number of environmental and economic benefits in those countries [2]. however, in many developing countries including vietnam, there are lacking of such regulations and guidance in place. in these countries, discarded tires have been largely treated in unsustainable manners. at present, enormous quantities of discarded tires are already stockpiled (whole tire) or landfilled (shredded tire). such stockpiles pose serious environmental and health threats which could have severe long-term effects if not properly addressed. improperly stored tires are potential breeding grounds for disease-carrying insects and rodents. discarded tire landfilling is responsible for a serious ecological threat. mainly discarded tires disposal areas contribute to the reduction of biodiversity as the tires hold toxic and soluble components. secondly although discarded tires are difficult to ignite, this risk is always present. once tires start to burn down due to accidental causes, high temperature takes place and toxic fumes are generated which causes air pollution problem [3] besides the high temperature causes tires to melt, thus producing an oil that will contaminate soil and water [4]. in order to properly dispose of huge amount of discarded tires, use of innovative techniques to recycle them is important. worldwide, discarded tires have been recycled for different purposes such as energy recovery (use of tire derived fuel in cement kilns, paper mills or power plants); tire pyrolysis for producing gas, oil, and char [5] civil engineering applications (lightweight fill for embankments and retaining walls, leachate drainage material and alternative daily cover at municipal solid waste landfills, insulating layer beneath roads and behind retaining walls, etc.) [6-9]. on the other hand, consumption of natural aggregates (river sand, stone, etc.) for concrete production is rapidly increasing in countries around the world in order to meet the increasing needs of infrastructural development in the recent years. due to the overexploitation in many countries, the availability of these natural aggregates has been decreasing [10, 11]. the increasing shortage of natural aggregates has created an opportunity for using by-products as fine aggregate. reuse of waste rubber derived from discarded tires as a partial or full replacement of natural aggregates in construction activities not only reduces demand for exploitation of natural raw materials, but also reduces environmental pollution problems associated with disposal of discarded tires [12]. in this regard, a number of studies on the use of rubber aggregate derived from discarded tire for replacing natural aggregates in concrete have been conducted recently. rubber aggregates are obtained from discarded tires using two different technologies: mechanical grinding at ambient temperature and/or cryogenic grinding at a temperature below the glass transition temperature [13, 14]. although previous studies have achieved encouraging results, there are still several aspects related to the effects of replacing volume for traditional aggregates by rubber aggregate and the effects of size and shape of rubber particles on the mechanical properties of concrete, that need to be further studied. this paper presents the results of the first ever study in vietnam which aims to investigate the effects of different contents and sizes of rubber particles derived from discarded tires used as aggregates for replacing fine and coarse natural aggregates on the workability of fresh rubberized concrete, the compressive and flexural strengths of hardened rubberized concrete. table-1. major properties of materials properties unit values 1. portland cement pc40 fineness: particles retained on 90 m sieve % 0 specific gravity g/cm3 3.10 initial time of setting minute 105.00 final time of setting minute 180.00 compressive strength at 3 days ± 45min mpa 28.80 compressive strength at 28 days ± 8 hours mpa 46.70 2. fly ash total content of sio2, al2o3, fe2o3 % 90.51 fineness: particles retained on 45 m sieve % 23.20 water absorption % 2.00 strength activity index  at 7 days  at 28 days % 80.10 84.80 3. sand specific gravity g/cm3 2.60 water absorption % 2.10 fineness modulus mm 2.65 4. crushed stone specific gravity g/cm3 2.65 water absorption % 1.50 fineness modulus mm 6.48 5. rubber specific gravity g/cm3 1.17 water absorption % 0 particle size  fine  coarse mm 2.50 5.00 5.00 20.00 asian review of environmental and earth sciences, 2017, 4(1): 12-19 14 2. experimental study 2.1. materials in this study, the ordinary portland cement pc 40 and fly ash (fa) were used as the binders. the physical, chemical and mechanical properties of the portland cement and fa are given in table 1. the portland cement pc 40 is produced by the local company named jsc vicem but son cement with its properties determined according to [15-17]. the percentage of cement retained on a 90 μm sieve as specified by vietnam standard [15] was 0 %. the fa was obtained from the local power plant (pha lai power plant in hai duong province, northeast of vietnam). according to astm c618-15 [18] the fa can be classified as a class f fly ash due to its chemical composition. in addition to having pozzolanic properties, this type of fa also has some cementitious properties. the total content of sio2, al2o3, and fe2o3 in fa is 90.51%, which is larger than the value given by the astm c618-15 standard for class f fly ash. the amount of fa retained on a 45 m sieve was 23.20%, which is less than the value given in astm c618-15 standard [18]. sand and crushed stone were used as fine and coarse aggregates in the concrete mix, respectively. the major properties of these materials were determined following [19] and given in table 1. the sand used complies to the description of astm c778 [20] and its gradation was in agreement to the requirement of astm c33/c33m [21]. in this study, the size of crushed stone was in the range of 5-20 mm. coarse (5-20 mm) and fine (2.5-5 mm) rubber particles used in the experiment were obtained from mechanical shredding of discarded tires. the physical properties of rubber particles are shown in table 1. 2.2. concrete mix design eleven different mix designs (m0-m10) were considered in this study. the control design (m0), containing no rubber, was determined using the absolute volume method, and consisted of 332 kg of cement, 58.5 kg of fa, 680 kg of sand (fine aggregate), 1200 kg of crushed stone (coarse aggregate), 155 kg of water, 2.73 kg of superplasticizer, and all per cubic meter of mix. the other five mixes (m1-m5) had fine aggregate replaced by fine rubber particle of equal volume, in 10% increments, up to 50% rubber replacement. similarly, the remaining five mixes (m6-m10) had coarse aggregate replaced by coarse rubber particle of equal volume, in 10% increments, up to 50% rubber replacement. table-2. concrete mix design (calculated for 1m3 concrete) mix id cement fly ash sand crushed stone water fine rubber particle coarse rubber particle superplasticizer weight (kg) weight (kg) weight (kg) weight (kg) weight (kg) weight (kg) % by volume weight (kg) % by volume weight (kg) m0 332 58.5 680 1200 155 0 0% 0 0% 2.73 m1 332 58.5 612 1200 155 30.18 10% 0 0% 2.73 m2 332 58.5 544 1200 155 60.35 20% 0 0% 2.73 m3 332 58.5 476 1200 155 90.53 30% 0 0% 2.73 m4 332 58.5 408 1200 155 120.71 40% 0 0% 2.73 m5 332 58.5 340 1200 155 150.88 50% 0 0% 2.73 m6 332 58.5 680 1080 155 0 0% 52.27 10% 2.73 m7 332 58.5 680 960 155 0 0% 104.53 20% 2.73 m8 332 58.5 680 840 155 0 0% 156.80 30% 2.73 m9 332 58.5 680 720 155 0 0% 209.07 40% 2.73 m10 332 58.5 680 600 155 0 0% 261.33 50% 2.73 the amount of cement, fa, water, and superplasticizer were all held constant, to reduce the number of variables and maintain a water-to-cement ratio of 0.47 for all mixes. the weights of aggregates and rubber in each mix can be found in table 2. 2.3. specimen preparation and test setup a. slump test in order to evaluate the effect of rubber particles derived from discarded tires replacing natural aggregates on the workability of fresh rubberized concrete, slump tests were performed for all mixes (table 2) according to vietnam standard [22]. b. compressive strength test the compressive strength tests were performed for all mixes according to vietnam standard [23] in order to evaluate the effect of fine and coarse aggregate replacement with fine and coarse rubber particles, respectively, on the compressive strength of hardened concrete. mix proportions used to prepare specimens for the compressive strength tests were those presented in table 2. one set of three cubic specimens with a side of 150 mm was realized for each mixture studied. specimens were cast using appropriate moulds placed on a vibration table for 60 seconds in order to obtain a more homogeneous distribution of rubber particles in concrete mix. after casting, the moulds were left to cure for 24 hours. once hardened, specimens were accurately demoulded, placed in a curing room at a relative humidity of 75% and a temperature of 27 ± 2 °c until testing time. the compressive tests were then carried out for both 7 and 28 day aged specimens by an oil-pressure machine under loading control with a capacity of 3,000 kn and the loading rate of 0.4 mpa/s. c. flexural strength test the flexural strength tests were also performed for all mixes according to vietnam standard [24] in order to evaluate the effect of fine and coarse aggregate replacement with fine and coarse rubber particles, respectively on the flexural strength of hardened concrete. employed mix proportions for preparing specimens for the flexural asian review of environmental and earth sciences, 2017, 4(1): 12-19 15 strength tests were the same presented in table 2. one set of three specimens with measuring 150 × 150 × 600 mm was cast for each mix design. the casting and curing procedures were similar to those reported above for the compressive strength tests. for the flexural strength test, three specimens from each mix design were tested by one-point loading configuration with a span of 10 cm using testing machine with a capacity of 10 kn and the loading rate of 0.06 mpa/s. all tests were carried out 28 days after casting. figure-1. impact of proportion and size of rubber particles replacing fine and coarse aggregates on slump of fresh rubberized concrete 3. results and discussions 3.1. workability of fresh rubberized concrete the results of slump tests are shown in figure 1. when sand (fine aggregate) was replaced by fine rubber particle at the low proportions (10% and 20% by volume), it can be seen that the slumps or workability of fresh rubberized concrete were not changed much compared to that of the control mix (m0). at the higher replacing proportions (30%, 40% and 50% by volume), the slumps relatively increased. our results are in good agreement with those reported by previous studies [25-29] where the workability of fresh rubberized concrete increased with increasing rubber contents. for instances, aiello and leuzzi [26] showed that the workability of rubberized concrete was slightly improved when coarse or fine aggregates were partially replaced with rubber shreds. they reported that the control concrete exhibited a fluid behavior, while the rubberized concrete showed a hyper-fluid behavior. similarly, balaha, et al. [25] used ground waste tire rubber for partial replacement of natural sand at the proportions of 0%, 5%, 10%, 15% and 20%, by volume and they reported that the workability increased as rubber sand content increased. however, it is worth to note that the other studies reported contrary results with the decreased workability as rubber aggregates included in the concrete mixture [30-33]. when crushed stone (coarse aggregate) was partially replaced by coarse rubber particle at the low and medium proportions (10%, 20%, and 30% by volume), it was observed that the slumps slightly increased in comparing to that of the control mix. however, when the replacing proportion increased to 40%, the slump slightly decreased. especially, at the replacing proportion of 50%, the slump was found to be decreased significantly. this can be explained that when coarse rubber particles were used at high proportion, the contacts among coarse rubber particles and among rubber particles with other aggregates increased leading to the increase in the inter-particle friction between rubber particles and other aggregates, thus reduce the workability of fresh rubberized concrete. our slump test results for the case of coarse rubber particle replacing coarse aggregate are also similar to those reported by the other studies [1, 34-40]. turgut and yesilata [35] partially replaced sand in concrete block mixtures with rubber aggregate at the proportions ranging from 10% to 70% with an increment of 10%, by volume. their results showed that the workability increased with the inclusion of rubber aggregate up to 40%, whereas the inclusion of 50-70% rubber aggregate caused the decreased workability. pacheco-torgal, et al. [1] reported that when rubber chips used to partially replace for coarse aggregate, the slump increased with increasing volume of rubber aggregates up to the replacing proportion of 15%, and the slump decreased as the replacing proportions were larger than 15% by volume. compared results on the workability of fresh rubberized concrete between this study and other studies suggest that the workability may be largely dependent on the specific characteristics of the rubber aggregates used in the concrete mixture. therefore, future studies should focus more on the characteristics of rubber aggregates (size, shape, pretreatment of rubber aggregates, etc.) that influence the workability of rubberized concrete. asian review of environmental and earth sciences, 2017, 4(1): 12-19 16 figure-2. impact of replacing proportion and size of rubber particles on compressive strength of hardened rubberized concrete 3.2. mechanical properties of hardened rubberized concrete a. compressive strength the 7-day and 28-day compressive strengths as a function of different replacing proportions of rubber particles with different sizes are presented in figure 2. as expected, the compressive strength increased with curing time for the control specimen (m0) and other specimens (m1-m10) at all replacing proportions. the compressive strength of the control specimen was evaluated as 34.5 and 49.5 mpa at 7 and 28 days, respectively. the test results indicated that there was a significant reduction in the compressive strength of rubberized concrete as the rubber content increased in comparison to that of the control specimen at both 7 and 28 days. table-3. reduction (%) in compressive strength of rubberized concrete compared to plain concrete cured time (day) specimen (proportion of natural aggregates replaced with rubber particles, % by volume) m0 (0%) m1 (10%) m2 (20%) m3 (30%) m4 (40%) m5 (50%) reduction (%) in compressive strength of rubberized concrete using fine rubber particle to replace fine aggregate 7 0 8.7 14.2 36.5 48.4 57.7 28 0 9.7 24.8 38.2 58.4 65.5 m0 (0%) m6 (10%) m7 (20%) m8 (30%) m9 (40%) m10 (50%) reduction (%) in compressive strength of rubberized concrete using coarse rubber particle to replace coarse aggregate 7 0 16.2 34.2 45.8 58.0 71.0 28 0 30.3 41.4 47.5 65.7 72.7 it is found that depending on the proportion and size of replacing rubber particles, the degree of reduction in the compressive strength was different (table 3). at the replacing proportion of 10%, the reduction in the compressive strength of the specimens containing fine rubber particles at 7 and 28 days were 8.7 and 9.7%, respectively; whilst the counterpart for the specimens containing coarse rubber particles at 7 and 28 days were 16.2 and 30.3%, respectively. this suggests that using coarse rubber particles lowered the compressive strength of rubberized concrete more than the case of using fine rubber particles. when the replacing proportions increased to 20, 30, and 40% by volume, the compressive strengths also decreased accordingly, however, the degrees of reduction between two cases (the specimens containing fine and coarse rubber particles) at the same replacing proportions gradually became smaller than that at the replacing proportion of 10%, especially for the specimens at the curing time of 28 days. the replacing proportion of 50% caused the largest reductions in the compressive strength of specimens containing fine and coarse rubber particles at both 7 and 28 days. the test results imply that using fine rubber particles, instead of fine natural aggregate, at the low replacing proportion (up to 10%) might not cause the significant effect on the compressive strength of rubberized concrete. overall, our results agreed well with previous studies which reported that the inclusion of increasing rubber contents caused progressive losses in the compressive strength of rubberized concrete and the replacement of coarse aggregate in the concrete mixture lowered the compressive strength more than that of fine aggregate [26, 31, 40-44]. there are several possible reasons for the reduction in the compressive strength of rubberized concrete which largely influenced by the physical and mechanical properties of constituent aggregates. first, it could be attributed to the physical properties of rubber particles which are less stiff than cement paste. this could lead to the deformability of rubber particles compared with surrounding cement paste that resulted in the rapid development of cracks around rubber particles in a fashion similar to that occurring with air voids in normal concrete [41, 45, 46]. the second reason for the decrease in the compressive strength is the poor bond between rubber particles and asian review of environmental and earth sciences, 2017, 4(1): 12-19 17 cement paste in comparing to the bond between natural aggregates and cement paste. corinaldesi, et al. [47] and raj, et al. [48] indicated that the low strength of rubberized concrete is due to the weak interface or transition zone between rubber particles and cement paste. such a weak interface could initially cause micro-cracks which eventually grow to macro-cracks, and result in the failure of rubberized concrete specimen under compression. our test results showed the surfaces of the failed specimens having quite clean rubber particles with little cement paste attached which implies the poor bond between rubber particles and cement paste. the third reason for the reduction in the compressive strength of rubberized concrete might be associated with the low specific gravity of rubber, coupled with the poor bond of rubber particles with other aggregates, which might make rubber particles moving upwards during vibration in the casting process and concentrating at the top layer of the specimen. this could result in a non-homogeneous distribution of rubber particles and other aggregates, and therefore reduce the strength of the specimen. the other reason for the decreased compressive strength could be the increased matrix porosity or weakness points in rubberized concrete matrix which largely depending on the size, density, and hardness of aggregates as explained by the previous studies [45, 49, 50]. figure-3. impacts of replacing proportion and size of rubber particles on flexural strength at 28 days of hardened rubberized concrete b. flexural strength the influences of different replacing proportions and different sizes of rubber particles on the 28-day flexural strengths of rubberized concrete are presented in figure 3. the flexural strength at 28 days of the control specimen was 7.2 mpa. similar to the case of the compressive strength, the test results indicated that there were significant reductions in the flexural strength of rubberized concrete specimens compared to the control specimen when replacing proportions increased. table-4. reduction (%) in flexural strength at 28 days of rubberized concrete compared to plain concrete specimen (proportion of natural aggregates replaced with rubber particles, % by volume) m0 (0%) m1 (10%) m2 (20%) m3 (30%) m4 (40%) m5 (50%) reduction (%) in flexural strength of rubberized concrete using fine rubber particle to replace fine aggregate 0 12.5 19.4 34.7 45.8 56.9 m0 (0%) m6 (10%) m7 (20%) m8 (30%) m9 (40%) m10 (50%) reduction (%) in flexural strength of rubberized concrete using coarse rubber particle to replace coarse aggregate 0 27.8 37.5 52.8 61.1 68.1 the degree of reduction in the flexural strength was also largely influenced by the size of replacing rubber particles as shown in table 4. as expected, a smaller reduction of the flexural strength was observed when fine aggregate was replaced by fine rubber particle, compared to the case of coarse rubber particle, for all replacing proportions. this could be attributed to the filling effect of fine rubber particles that increase the compactness of rubberized concrete specimens, reduce the stress singularity at internal voids, and thus reduce the likelihood of fracture [51]. the test results suggest that using fine rubber particles for replacing fine natural aggregate at the low replacing proportion (up to 10%) might not cause the significant effect on the flexural strength of rubberized concrete which similar to the case of the compressive strength. similar test results were reported by the previous studies [26, 41, 51]. for instances, aiello and leuzzi [26] reported that rubberized concrete with the inclusion of 50% and 75% by volume of coarse aggregate replacement presented 28% decrease in the flexural strength compared to plain concrete. whereas, rubberized concrete obtained with 50% and 75% by volume of fine aggregate replacement showed a decrease in the flexural strength of about 5.8% and 7.3%, respectively compared to plain concrete. however, it is worth to note that the other studies have asian review of environmental and earth sciences, 2017, 4(1): 12-19 18 reported quite different results compared to ours with the increased flexural strength of rubberized concrete when rubber aggregate used to replace fine aggregate at the low replacing proportions (mainly less than 20% by volume), and the decreased flexural strength at the high replacing proportions. for instances, yilmaz and degirmenci [42] reported that rubberized concrete specimens using tire rubber (in the form of fibers) up to 20% by volume showed the higher flexural strength than control specimens, and the flexural strength decreased as rubber contents increased from 20-30%. gupta, et al. [52] reported that the flexural strength of rubberized concrete containing rubber ash decreased as the content of rubber ash increased, whereas the flexural strength of modified concrete (containing 10% rubber ash and a varying content of rubber fibers) increased with the increasing content of rubber fibers. these studies showed that the increased flexural strength of rubberized concrete associated with the use of tire rubber in the form of fibers. this further suggests that future studies should focus on the characteristics of the rubber aggregates that enhance the flexural strength of rubberized concrete. 4. conclusions this study has conducted the experiment to investigate the properties of fresh and hardened rubberized concrete made by replacing natural aggregates with rubber particles derived from discarded tires having similar sizes of replaced natural aggregates. the major findings of this study can be summarized as the following:  the workability of fresh rubberized concrete improved when replacing natural fine aggregate with fine rubber particles at the replacing proportions of 30-50% by volume, and when replacing natural coarse aggregate with coarse rubber particles at the replacing proportions of 10-30% by volume;  with respect to the mechanical properties of hardened rubberized concrete, a larger reduction in the compressive and flexural strengths was generally observed when replacing proportions increased, and especially when coarse aggregate rather than fine aggregate was replaced by rubber particles at all replacing proportions (10-50% by volume).  using fine rubber particles for replacing fine natural aggregate at the low replacing proportion (up to 10%) might not cause the significant effect on the compressive and flexural strength of rubberized concrete. based on the findings of this study, further studies are recommended to verify the workability and the mechanical properties of rubberized concrete mixtures prepared by partially replacing both natural coarse and fine aggregates, and to evaluate effects of specific characteristics (e.g. size, shape, pretreatment) of rubber aggregates on the workability and the mechanical properties of rubberized concrete, especially characteristics that could increase the mechanical properties of rubberized concrete. references [1] f. pacheco-torgal, y. ding, and s. jalali, "properties and durability of concrete containing polymeric wastes (tyre rubber and polyethylene terephthalate bottles): an overview," constr build mater, vol. 30, pp. 714–724, 2012. view at google scholar | view at publisher [2] j. w. jang, t. s. yoo, j. h. oh, and i. iwasaki, "discarded tire recycling practices in the united states, japan and korea," resources, conservation and recycling, vol. 22, pp. 1–14, 1998. view at google scholar | view at publisher [3] k. e. day, k. e. holtze, s. j. l. metcalfe, c. t. bishop, and b. j. dutka, "toxicity of leachate from automobile tyres to aquatic biota," chemosphere, vol. 27, pp. 665–675, 1993. view at google scholar | view at publisher [4] t. amari, n. j. themelis, and i. k. wernick, "resource recovery from used rubber tires," resour policy, vol. 25, pp. 179–188, 1999. view at google scholar | view at publisher [5] x. shu and b. s. huang, "recycling of waste tire rubber in asphalt and port land cement concrete: an overview," construction and building materials, vol. 67, pp. 217-224, 2014. view at google scholar | view at publisher [6] m. r. merino, c. a. j. santa, and c. m. gonzález, "viability analysis and constructive applications of lightened mortar rubber cement mortar," construction and building materials, vol. 21, pp. 1785–1791, 2007. view at google scholar | view at publisher [7] n. al-akhras and m. m. samadi, "properties of tire rubber ash mortar," cement and concrete composites, vol. 26, pp. 821–826, 2004. view at google scholar | view at publisher [8] a. benazzouk, o. douzane, and m. quéneudec, "transport of fluids in cement-rubber composites," cement and concrete composites, vol. 26, pp. 21–29, 2004. view at google scholar | view at publisher [9] s. h. chen, h. y. wang, and j. w. jhou, "investigating the properties of lightweight concrete containing high contents of recycled green building materials," construction and building materials, vol. 48, pp. 98–103, 2013. view at google scholar | view at publisher [10] a. m. rashad, "a preliminary study on the effect of fine aggregate replacement with metakaolin on strength and abrasion resistance of concrete," construction and building materials, vol. 44, pp. 448–495, 2013. view at google scholar | view at publisher [11] a. m. rashad, "recycled waste glass as fine aggregate replacement in cementitious materials based on portland cement," construction and building materials, vol. 72, pp. 340–357, 2014. view at google scholar | view at publisher [12] a. m. rashad, "a comprehensive overview about recycling rubber as fine aggregate replacement in traditional cementitious materials," international journal of sustainable built environment, vol. 5, pp. 46-82, 2016. view at google scholar | view at publisher [13] k. nagdi, rubber as an engineering material: guidelines for user. munich; new york: hanser publication, 1993. [14] w. eleazer, m. barlaz, and d. whittle, resource recovery alternatives for waste tires in north carolina. us: school of engineering, civil engineering department, ncsu, 1992. [15] vietnam standard, "tcvn 4030-2003 cement test method for determination of fineness in vietnamese," vietnam ministry of science and technology, 2003. [16] vietnam standard, "tcvn 6017-1995 (iso 9597:1989) cements test methods determination of setting time and soundness in vietnamese," vietnam ministry of science technology and environment, 1995. [17] vietnam standard, "tcvn 6016-2011 (iso 679:2009) cements test methods determination of strength in vietnamese," vietnam ministry of science and technology, 2011. [18] astm, astm c618–15 standard specification for coal fly ash and raw or calcined, natural pozzolan for use in concrete. west conshohocken, pa, usa: astm international, 2015. [19] vietnam standard, "tcvn 7572-4:2006 aggregates for concrete and mortar test methods part 4: determination of apparent specific gravity, bulk specific gravity and water absorption in vietnamese," vietnam ministry of science and technology, 2006. [20] astm, astm c778-13 standard specification for standard sand. west conshohocken, pa: astm international, 2013. [21] astm, astm c33/c33m-16e1 standard specification for concrete aggregates. west conshohocken, pa: astm international, 2016. [22] vietnam standard, "tcvn 3106:1993 heavyweight concrete compounds slump test in vietnamese," vietnam ministry of science technology and environment, 1993. [23] vietnam standard, "tcvn 3118:1993 heavyweight concrete method for determination of compressive strength in vietnamese," vietnam ministry of science technology and environment, 1993. [24] vietnam standard, "tcvn 3119:1993 heavyweight concrete method for determination of flexural tensile strength in vietnamese," vietnam ministry of science technology and environment, 1993. [25] m. m. balaha, a. a. m. badawy, and m. hashish, "effect of using ground tire rubber as fine aggregate on the behaviour of concrete mixes," indian journal of engineering and materials sciences, vol. 14, pp. 427–435, 2007. view at google scholar https://scholar.google.com/scholar?hl=en&q=properties%20and%20durability%20of%20concrete%20containing%20polymeric%20wastes%20(tyre%20rubber%20and%20polyethylene%20terephthalate%20bottles):%20an%20overview http://dx.doi.org/10.1016/j.conbuildmat.2011.11.047 https://scholar.google.com/scholar?hl=en&q=discarded%20tire%20recycling%20practices%20in%20the%20united%20states,%20japan%20and%20korea http://dx.doi.org/10.1016/s0921-3449(97)00041-4 https://scholar.google.com/scholar?hl=en&q=toxicity%20of%20leachate%20from%20automobile%20tyres%20to%20aquatic%20biota http://dx.doi.org/10.1016/0045-6535(93)90100-j https://scholar.google.com/scholar?hl=en&q=resource%20recovery%20from%20used%20rubber%20tires http://dx.doi.org/10.1016/s0301-4207(99)00025-2 https://scholar.google.com/scholar?hl=en&q=recycling%20of%20waste%20tire%20rubber%20in%20asphalt%20and%20port%20land%20cement%20concrete:%20an%20overview http://dx.doi.org/10.1016/j.conbuildmat.2013.11.027 https://scholar.google.com/scholar?hl=en&q=viability%20analysis%20and%20constructive%20applications%20of%20lightened%20mortar%20rubber%20cement%20mortar http://dx.doi.org/10.1016/j.conbuildmat.2006.05.014 https://scholar.google.com/scholar?hl=en&q=properties%20of%20tire%20rubber%20ash%20mortar http://dx.doi.org/10.1016/j.cemconcomp.2004.01.004 https://scholar.google.com/scholar?hl=en&q=transport%20of%20fluids%20in%20cement-rubber%20composites http://dx.doi.org/10.1016/j.cemconcomp.2004.01.004 https://scholar.google.com/scholar?hl=en&q=investigating%20the%20properties%20of%20lightweight%20concrete%20containing%20high%20contents%20of%20recycled%20green%20building%20materials http://dx.doi.org/10.1016/j.conbuildmat.2013.06.040 https://scholar.google.com/scholar?hl=en&q=a%20preliminary%20study%20on%20the%20effect%20of%20fine%20aggregate%20replacement%20with%20metakaolin%20on%20strength%20and%20abrasion%20resistance%20of%20concrete http://dx.doi.org/10.1016/j.conbuildmat.2013.03.038 https://scholar.google.com/scholar?hl=en&q=recycled%20waste%20glass%20as%20fine%20aggregate%20replacement%20in%20cementitious%20materials%20based%20on%20portland%20cement http://dx.doi.org/10.1016/j.conbuildmat.2014.08.092 https://scholar.google.com/scholar?hl=en&q=a%20comprehensive%20overview%20about%20recycling%20rubber%20as%20fine%20aggregate%20replacement%20in%20traditional%20cementitious%20materials http://dx.doi.org/10.1016/j.ijsbe.2015.11.003 https://scholar.google.com/scholar?hl=en&q=effect%20of%20using%20ground%20tire%20rubber%20as%20fine%20aggregate%20on%20the%20behaviour%20of%20concrete%20mixes asian review of environmental and earth sciences, 2017, 4(1): 12-19 19 [26] m. a. aiello and f. leuzzi, "waste tyre rubberized concrete: properties at fresh and hardened state," waste management, vol. 30, pp. 1696–1704, 2010. view at google scholar | view at publisher [27] f. pelisser, a. barcelos, d. santos, m. peterson, a. michael, and a. bernardin, "lightweight concrete production with low portland cement consumption," journal of cleaner production, vol. 23, pp. 68–74, 2012. view at google scholar | view at publisher [28] o. onuaguluchi and d. k. panesar, "hardened properties of concrete mixtures containing pre-coated crumb rubber and silica fume," journal of cleaner production, vol. 82, pp. 125–131, 2014. view at google scholar | view at publisher [29] m. elchalakani, "high strength rubberized concrete containing silica fume for the construction of sustainable road side barriers," structures, vol. 1, pp. 20–38, 2015. view at google scholar | view at publisher [30] n. ganesan, j. b. raj, and a. p. shashikala, "flexural fatigue behavior of self-compacting rubberized concrete," construction and building materials, vol. 44, pp. 7–14, 2013. view at google scholar | view at publisher [31] n. holmes, a. browne, and c. montague, "acoustic properties of concrete panels with crumb rubber as a fine aggregate replacement," construction and building materials, vol. 73, pp. 195–204, 2014. view at google scholar | view at publisher [32] z. grdić, g. topličić-ćurčić, n. ristić, d. grdić, and p. mitković, "hydro-abrasive resistance and mechanical properties of rubberized concrete," gradeinar, vol. 66, pp. 11–20, 2014. view at google scholar | view at publisher [33] i. mohammadi, h. khabbaz, and k. vessalas, "in-depth assessment of crumb rubber concrete (crc) prepared by water-soaking treatment method for rigid pavements," construction and building materials, vol. 71, pp. 456–471, 2014. view at google scholar | view at publisher [34] a. r. khaloo, m. dehestani, and p. rahmatabadi, "mechanical properties of concrete containing a high volume of tire-rubber particles," waste management, vol. 28, pp. 2472–2482, 2008. view at google scholar | view at publisher [35] p. turgut and b. yesilata, "physico-mechanical and thermal performance of newly developed rubber-added bricks," energy build, vol. 40, pp. 679–688, 2008. view at google scholar | view at publisher [36] s. d. parveen, d. sachin, and s. ankit, "rubberized concrete: needs of good environment overview," international journal of emerging technology and advanced engineering, vol. 3, pp. 192–196, 2013. view at google scholar [37] h. y. wang, b. t. chen, and y. w. wu, "a study of the fresh properties of controlled low-strength rubber lightweight aggregate concrete clsrlc," construction and building materials, vol. 41, pp. 526–531, 2013. view at google scholar | view at publisher [38] y. antil, v. verma, and b. singh, "rubberized concrete with crumb rubber," international journal of science and research, vol. 3, pp. 1481–1483, 2014. [39] y. c. guo, j. h. zhang, g. m. chen, and z. h. xie, "compressive behaviour of concrete structures incorporating recycled concrete aggregates, rubber crumb and reinforced with steel fibre, subjected to elevated temperatures," journal of cleaner production, vol. 72, pp. 193–203, 2014. view at google scholar | view at publisher [40] o. youssf, m. a. elgaeady, j. e. mills, and x. ma, "an experimental investigation of crumb rubber concrete confined by fibre reinforced polymer tubes," construction and building materials, vol. 53, pp. 522–532, 2014. view at google scholar | view at publisher [41] e. ganjian, m. khorami, and a. a. maghsoudi, "scrap-tyre-rubber replacement for aggregate and filler in concrete," construction and building materials, vol. 23, pp. 1828–1836, 2009. view at google scholar | view at publisher [42] a. yilmaz and n. degirmenci, "possibility of using waste tire rubber and fly ash with portland cement as construction materials," waste management, vol. 29, pp. 1541–1546, 2009. view at google scholar | view at publisher [43] f. pelisser, z. nilomar, l. tiago, a. bernardin, and a. michael, "concrete made with recycled tire rubber: effect of alkaline activation and silica fume addition," journal of cleaner production, vol. 196, pp. 757–763, 2011. view at google scholar | view at publisher [44] m. gesoğlu, e. güneyisi, g. khoshnaw, and s. i̇pek, "investigating properties of pervious concretes containing waste tire rubbers," construction and building materials, vol. 63, pp. 206–213, 2014. view at google scholar | view at publisher [45] m. m. taha, a. s. el-dieb, m. a. abdel-wahab, and m. e. abdel-hameed, "mechanical, fracture, and microstructural investigations of rubber concrete," journal of materials in civil engineering, vol. 20, pp. 640–649, 2008. view at google scholar | view at publisher [46] b. s. thomas and r. c. gupta, "a comprehensive review on the applications of waste tire rubber in cement concrete," renewable & sustainable energy reviews, vol. 54, pp. 1323–1333, 2016. view at google scholar | view at publisher [47] v. corinaldesi, a. mazzoli, and g. moriconi, "mechanical behaviour and thermal conductivity of mortars containing waste rubber particles," materials & design, vol. 32, pp. 1646–1650, 2011. view at google scholar | view at publisher [48] b. raj, n. ganesan, and a. p. shashikala, "engineering properties of self-compacting rubberized concrete," journal of reinforced plastics and composites, vol. 30, pp. 1923–1930, 2011. view at google scholar | view at publisher [49] c. albano, n. camacho, j. reyes, j. l. feliu, and m. hernández, "influence of scrap rubber to portland i concrete composites: destructive and non-destructive testing," composite structures, vol. 71, pp. 439–446, 2005. view at google scholar | view at publisher [50] m. turki, e. bretagne, m. j. rouis, and m. quéneudec, "microstructure, physical and mechanical properties of mortar-rubber aggregates mixtures," construction and building materials, vol. 23, pp. 2715–2722, 2009. view at google scholar | view at publisher [51] h. su, j. yang, t. c. ling, g. s. ghataora, and s. dirar, "properties of concrete prepared with waste tyre rubber particles of uniform and varying sizes," journal of cleaner production, vol. 91, pp. 288–296, 2014. [52] t. gupta, s. chaudhary, and r. k. sharma, "assessment of mechanical and durability properties of concrete containing waste rubber tire as fine aggregate," construction and building materials, vol. 73, pp. 562–574, 2014. view at google scholar | view at publisher asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=waste%20tyre%20rubberized%20concrete:%20properties%20at%20fresh%20and%20hardened%20state http://dx.doi.org/10.1016/j.sbspro.2013.06.643 https://scholar.google.com/scholar?hl=en&q=lightweight%20concrete%20production%20with%20low%20portland%20cement%20consumption http://dx.doi.org/10.1016/j.jclepro.2011.10.010 https://scholar.google.com/scholar?hl=en&q=hardened%20properties%20of%20concrete%20mixtures%20containing%20pre-coated%20crumb%20rubber%20and%20silica%20fume http://dx.doi.org/10.1016/j.jclepro.2014.06.068 https://scholar.google.com/scholar?hl=en&q=high%20strength%20rubberized%20concrete%20containing%20silica%20fume%20for%20the%20construction%20of%20sustainable%20road%20side%20barriers http://dx.doi.org/10.1016/j.istruc.2014.06.001 https://scholar.google.com/scholar?hl=en&q=flexural%20fatigue%20behavior%20of%20self-compacting%20rubberized%20concrete http://dx.doi.org/10.1016/j.conbuildmat.2013.02.077 https://scholar.google.com/scholar?hl=en&q=acoustic%20properties%20of%20concrete%20panels%20with%20crumb%20rubber%20as%20a%20fine%20aggregate%20replacement http://dx.doi.org/10.1016/j.conbuildmat.2014.09.107 https://scholar.google.com/scholar?hl=en&q=hydro-abrasive%20resistance%20and%20mechanical%20properties%20of%20rubberized%20concrete http://dx.doi.org/10.14256/jce.910.2013 https://scholar.google.com/scholar?hl=en&q=in-depth%20assessment%20of%20crumb%20rubber%20concrete%20(crc)%20prepared%20by%20water-soaking%20treatment%20method%20for%20rigid%20pavements http://dx.doi.org/10.1016/j.conbuildmat.2014.08.085 http://dx.doi.org/10.1016/j.conbuildmat.2014.08.085 https://scholar.google.com/scholar?hl=en&q=mechanical%20properties%20of%20concrete%20containing%20a%20high%20volume%20of%20tire-rubber%20particles http://dx.doi.org/10.1016/j.wasman.2008.01.015 https://scholar.google.com/scholar?hl=en&q=physico-mechanical%20and%20thermal%20performance%20of%20newly%20developed%20rubber-added%20bricks http://dx.doi.org/10.1016/j.enbuild.2007.05.002 https://scholar.google.com/scholar?hl=en&q=rubberized%20concrete:%20needs%20of%20good%20environment%20overview https://scholar.google.com/scholar?hl=en&q=a%20study%20of%20the%20fresh%20properties%20of%20controlled%20low-strength%20rubber%20lightweight%20aggregate%20concrete%20clsrlc http://dx.doi.org/10.1016/j.conbuildmat.2012.11.113 https://scholar.google.com/scholar?hl=en&q=compressive%20behaviour%20of%20concrete%20structures%20incorporating%20recycled%20concrete%20aggregates,%20rubber%20crumb%20and%20reinforced%20with%20steel%20fibre,%20subjected%20to%20elevated%20temperatures http://dx.doi.org/10.1016/j.jclepro.2014.02.036 https://scholar.google.com/scholar?hl=en&q=an%20experimental%20investigation%20of%20crumb%20rubber%20concrete%20confined%20by%20fibre%20reinforced%20polymer%20tubes http://dx.doi.org/10.1016/j.conbuildmat.2013.12.007 https://scholar.google.com/scholar?hl=en&q=scrap-tyre-rubber%20replacement%20for%20aggregate%20and%20filler%20in%20concrete http://dx.doi.org/10.1016/j.conbuildmat.2008.09.020 https://scholar.google.com/scholar?hl=en&q=possibility%20of%20using%20waste%20tire%20rubber%20and%20fly%20ash%20with%20portland%20cement%20as%20construction%20materials http://dx.doi.org/10.1016/j.wasman.2008.11.002 https://scholar.google.com/scholar?hl=en&q=concrete%20made%20with%20recycled%20tire%20rubber:%20effect%20of%20alkaline%20activation%20and%20silica%20fume%20addition http://dx.doi.org/10.1016/j.jclepro.2010.11.014 https://scholar.google.com/scholar?hl=en&q=investigating%20properties%20of%20pervious%20concretes%20containing%20waste%20tire%20rubbers http://dx.doi.org/10.1016/j.conbuildmat.2014.04.046 https://scholar.google.com/scholar?hl=en&q=mechanical,%20fracture,%20and%20microstructural%20investigations%20of%20rubber%20concrete http://dx.doi.org/10.1061/(asce)0899-1561(2008)20:10(640) http://dx.doi.org/10.1061/(asce)0899-1561(2008)20:10(640) https://scholar.google.com/scholar?hl=en&q=a%20comprehensive%20review%20on%20the%20applications%20of%20waste%20tire%20rubber%20in%20cement%20concrete http://dx.doi.org/10.1016/j.rser.2015.10.092 https://scholar.google.com/scholar?hl=en&q=mechanical%20behaviour%20and%20thermal%20conductivity%20of%20mortars%20containing%20waste%20rubber%20particles http://dx.doi.org/10.1016/j.matdes.2010.10.013 https://scholar.google.com/scholar?hl=en&q=engineering%20properties%20of%20self-compacting%20rubberized%20concrete http://dx.doi.org/10.1177/0731684411431356 https://scholar.google.com/scholar?hl=en&q=influence%20of%20scrap%20rubber%20to%20portland%20i%20concrete%20composites:%20destructive%20and%20non-destructive%20testing http://dx.doi.org/10.1016/j.compstruct.2005.09.037 https://scholar.google.com/scholar?hl=en&q=microstructure,%20physical%20and%20mechanical%20properties%20of%20mortar-rubber%20aggregates%20mixtures http://dx.doi.org/10.1016/j.conbuildmat.2008.12.019 https://scholar.google.com/scholar?hl=en&q=assessment%20of%20mechanical%20and%20durability%20properties%20of%20concrete%20containing%20waste%20rubber%20tire%20as%20fine%20aggregate http://dx.doi.org/10.1016/j.conbuildmat.2014.09.102 16 © 2019 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 6, no. 1, 16-27, 2019 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2019.61.16.27 © 2019 by the authors; licensee asian online journal publishing group radio direction finding (rdf) geomagnetic monitoring study of the himalaya area in search of pre-seismic electromagnetic signals valentino straser1 daniele cataldi2 gabriele cataldi3 ( corresponding author) 1department of science and environment upkl, brussels, belgium 2,3radio emissions project, rome, italy abstract the study proposes to present data on the broadband electromagnetic monitoring (self-vlf band, 0-32000 hz) able to work 24h7, within the electromagnetic monitoring network with rdf (radio direction finding) technology. the area monitored for the experimentation is the himalayan one, historically hit by strong and devastating earthquakes. the study collected 2991 groups of radio-anomalies, related to the crustal diagnosis and to non-destructive earthquakes. it is the first network of this type able to work on a wide bandwidth (elf-vlf band, 0-32000 hz) specially designed to study the so-called "seismic electromagnetic precursors" (seps) and the "seismic geomagnetic precursors" "(sgps). this monitoring system, based on rdf technology, has been active since 2017. in questo studio viene proposta una nuova chiave di lettura dei candidate precursori sismici, sperimentabili e verificabili anche in altre parti del mondo. the areas remotely monitored by the experimental station of rome and pisa, in italy, thousands of kilometers away show a convergence of the data and, in particular, the frequency bands that appear before the earthquakes of magnitude equal to or greater than 4.5 of the richter scale, about 72 hours before the main shock. the direction of the electromagnetic signal of the future epicentral area is intercepted by the rdf system. this is the first study for the analysis of em precursors worldwide. keywords: rdf system, earthquake prediction, self-vlf, himalayan area, seismic precursor, em pre-earthquake signals. citation | valentino straser; daniele cataldi; gabriele cataldi (2019). radio direction finding (rdf) geomagnetic monitoring study of the himalaya area in search of pre-seismic electromagnetic signals. asian review of environmental and earth sciences, 6(1): 16-27. history: received: 30 october 2018 revised: 2 december 2018 accepted: 14 january 2019 published: 7 march 2019 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 17 2. instrumental used ........................................................................................................................................................................... 17 3. the study .......................................................................................................................................................................................... 17 4. the data ............................................................................................................................................................................................ 17 5. conclusions ....................................................................................................................................................................................... 19 references .............................................................................................................................................................................................. 27 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2019.61.16.27&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/712 https://orcid.org/0000-0002-1736-1887 http://asianonlinejournals.com/index.php/arees/article/view/712 https://orcid.org/0000-0002-1736-1887 http://asianonlinejournals.com/index.php/arees/article/view/712 https://orcid.org/0000-0002-1736-1887 asian review of environmental and earth sciences, 2019, 6(1): 16-27 17 © 2019 by the authors; licensee asian online journal publishing group 1. introduction the devastating earthquake in bhuj, on january 26, 2001, highlighted the high risk of earthquakes in the indian region of gujarat (india). recent studies [1] have shown that we can expect strong and destructive earthquakes in the indian area and the one facing the himalayan arc. an analysis of historical earthquakes suggests that many important earthquakes should have already occurred in this region, but that recent low activity has focused attention away from the himalayan arc, citing scholars to underestimate the high risk of this area. the projections of previous earthquakes suggest that only one of the himalayan earthquakes that could occur soon, could cause about 200,000 victims [1]. the monitoring carried out by the radio emissions project showed that there are electromagnetic signals recorded before the strong earthquakes occurred on a global scale [2]; [3]; [4]; [5]; [6] and that such signals could be of predictive importance in a context of seismic prediction. this study, which began april 5, 2018, and ended december 31, 2018 was not only an opportunity to test the monitoring system developed by daniele and gabriele cataldi, but also to keep the himalayan area under close control, where it has been waiting for some time a strong and destructive earthquake. 2. instrumental used 2.1. the rdf station in lariano (rome, italy) the rdf station (radio direction finding) considered in this study is that of lariano (rome, italy, lat: 41.729535n, long: 12.840968e), equipped with two 1 meter of the diameter loop antennas containing 50 turns each figure 1 aligned with each other orthogonally and with respect to the geographic poles. it is managed by dr. daniele cataldi and is equipped with a prototype radio receiver designed and built by dr. gabriele cataldi that is able to detect changes in the electromagnetic field in the band vlf (0.3-32 khz) 24h7. 3. the study on april 5, 2018, the electromagnetic monitoring of the himalayan area began between the borders of china, tibet, nepal, bhutan, india, as shown in figure 2-3. this electromagnetic monitoring was made possible thanks to the rdf radio direction finding station of the electromagnetic detection system of the radio emissions project in lariano, rome, italy. 3.1. the monitored area the monitoring area is between 5.645 km and 7373 km from the lariano rdf station (rome, italy), as shown in figure 4. this distance, considering the reception characteristics of the rdf station itself, is not underestimated with respect to the total coverage of the station (with a radius of 20,000 km), reaching about 1/3 of the maximum coverage (in this case the experimentation took place in 2017) [2] as shown in figure 4. in this case, the electromagnetic monitored signals fall below the turquoise azimuth, tending to green, as evidenced by the colorimetric map of the rdf system of lariano (rm) figure 5. this azimuth is found in correspondence with the himalayan arc, in precise east position with respect to the italian geographical position where the rdf monitoring station is located. this geographical area is extremely large as shown in figure 5:  perimeter: over 4,600 km.  area: 909.444.439.316 km2. the monitoring system therefore had to keep under continuous electromagnetic control all the emissions from this large area, considering also the vicinity of the ring of fire, which is only a few thousand kilometers and which is a very broad natural emission transmitter continuous electromagnetic and strong intensity. the signals coming from this large area have often generated intense electromagnetic modulations, such as to cover the weak emissions coming from the himalayan arc. this is therefore one of the important data that should not be underestimated, which was nevertheless considered in this study and which represented a "limit" of the rdf system, in detecting further signals from the area under continuous monitoring. 4. the data 4.1. the signals the signals recorded by the rdf radio direction finding system, developed by the radio emissions project, concerned pulsatile or continuous increases at the turquoise azimuth (tending to green), these signals appeared very frequently, saturating, for most of the appearances, the entire electromagnetic band taken into consideration (32 khz bandwidth), as shown in figure 6. sporadic signals have instead appeared limited to certain frequencies, whose emission characteristics we will analyze later. the study addressed by the radio emissions project by means of the rdf station in lariano, rome, italy, highlighted some interesting features of radioanomalies recorded during the study, a study focused on the search for signals with characteristics of seismic predictivity in the himalayan area. the signals considered were only those polarized with himalayan azimuth, eliminating all the increases and electromagnetic peaks coming from other geographic areas of the terrestrial globe. the first interesting data are the number of anomalies (having the same azimuth of the monitored area), which appeared during the weeks and months in which this study lasted. the figure 7, concerning the number of radioanomalies highlighted between april 2018 and december 2018 (9 months), indicates that there has been a marked increase in the number of signals recorded around the end of august 2018, with 297 groups of signals ( 9.93%) out of a total of 2991 groups of radio-anomalies recorded and analyzed, after which we find a large number of radioanomalies between 22 may and 9 july 2018, with a total of 910 (30.42%) radio anomalies with the himalayan area as an azimuthal characteristic. asian review of environmental and earth sciences, 2019, 6(1): 16-27 18 © 2019 by the authors; licensee asian online journal publishing group a third increase in the number of radio-anomalies, however, appeared around april 20, 2018, with a total of 226 cases recorded (7.56%) as shown in figure 7. the variation in the number of such radio-anomalies, if we consider their electromagnetic frequency, shows very important details: almost all the signals had a full-band emission (0-32000 hz), with 2387 radio-anomalies (79.81 %). small percentages of signals instead concern the frequencies included between: 5700-7600; 9500-11400; 13300-15200 (20.19%). this shows us that almost 80% of emissions are able to cover the entire geomagnetic fund monitored, because they possess important physical characteristics, such as their intensity compared to the remaining natural geomagnetic bottom figure 8. this figure is certainly due to the enormous energy accumulated in the himalayan area, where there are sources of radio emissions coming, as already mentioned, from the nearby "belt of fire", where, as you know, the energy in accumulation at the crustal level it is notable compared to other areas of the globe. this energy can generate full-band electromagnetic emissions, able to reach long distances. the electromagnetic behavior of the recorded radio-anomalies indicates that the signals emitted in the direction of the himalayas are extremely wide in frequency and have a variable duration, from a few minutes to many hours. this is explainable because in this direction, we find continuous crustal emissions, the area known as the "fire circle", an area in which mechanical stress is practically continuous, finding ourselves on thousands of fault surfaces containing great energy of accumulation. the rdf system therefore receives, continuously, emissions from this area, being prospectively in the same azimuth position of the himalayan area. such a bandwidth of the signals could be determined, in fact, by overmodulation of hundreds of active faults, which saturate the local electromagnetic band, which the radio receiver used in this study and developed by the radio emissions project, is able to perceive and amplify, making them intelligible by the computerized system. in this context, however, the system recorded a huge number of signals from a distance of no less than 5,600 km. if we then go to see the time when these radio-anomalies are recorded by the rdf monitoring system, then we find the following data:  two main peaks of grouping of the number of radio-anomalies, was recorded between 06:08 utc and 07:40 utc (272 cases 9.9%);  a second peak was recorded again, between 09:12 utc and 10:45 utc (270 cases 9.03%).  a third grouping is instead visible between 13:49 utc and 16:53 utc (436 cases 14.58%).  a fourth grouping of anomalies is instead visible between 00:00 utc and about 01:32 utc (192 registered cases 6.42%). also in this case, as highlighted in previous studies [7] the recording or not of radio anomalies depends on solar activity and solar illumination with respect to the recording time. the ionospheric variations provide a more or less suitable substrate with respect to the propagation of the signals coming from the himalayan area. the majority of the radio-anomalies in this case study is highlighted precisely in the daytime, that is solar lighting, with respect to the position of the monitoring station as shown in figure 9. during the experimentation it was noted that out of a total of 2992 recorded cases, the behavior of the average frequency variation of the recorded radio anomalies increased drastically during the year figure 10. in this case, the electromagnetic emissions are almost all broadband, as already mentioned and as can be seen in figure 8 and figure 11. the change in this frequency showed a marked increase compared to the signals recorded during the first weeks of monitoring. on this increase in frequency it is not possible today to provide a univocal explanation. on this increase process solar activity could have interacted, with the approach to the solar minimum and the release of energy from the large pacific active faults. in fact, studies show that during the solar minimums (during which we are in the course of such monitoring), the energy accumulated by the planetary system is released, generating a greater number of natural catastrophic phenomena and not least the accumulation and the release of crustal energy [8]. obviously this is only a hypothesis and not a confirmed data, further studies will be needed to understand and understand the reason for these variations, compared to the data already obtained. 4.2. seismic data the seismic data relating to the himalayan area recorded during the study show a total of 47 earthquakes with magnitude m2.5 + of the richter scale figure 12. these earthquakes were considered in their appearance characteristics, compared to the time period in which the radio-anomalies occurred. the graphs from graph 1 to 9 show an evident and important data, that relating to the electromagnetic frequency and the occurrence of the earthquake. this report indicates that in the course of strong and lasting increases there are more earthquakes, compared to the period of time in which electromagnetic emissions are few. as regards such electromagnetic emissions, the greatest number of earthquakes seems to appear when there have been emissions with turquoise azimuth, having extended (full-band) electromagnetic frequency. this data would underline that when there is a huge flow of energy that releases itself, emitting strong and lasting electromagnetic emissions, an earthquake is most likely to be expected. the index of the electromagnetic frequency of the radio-anomalies also says that when the signals have a lower frequency or their appearance is intermittent and not lasting in time, the earthquakes have a lower magnitude, even if the number of such earthquakes is greater, compared to the periods in which the emissions are long, lasting and extended to full band, saturating the electromagnetic frequency monitored by the rdf system developed by the radio emissions project. asian review of environmental and earth sciences, 2019, 6(1): 16-27 19 © 2019 by the authors; licensee asian online journal publishing group 5. conclusions the total number of radio-anomalies recorded during the study is 2991, each of which correlated with himalayan azimuth. this number is associated with electromagnetic increments having different frequency as shown in figure 11 and duration. the data contained in this study were extrapolated from the monitoring system developed by daniele and gabriele cataldi, who independently detected the electromagnetic emissions, providing indications on their azimuthal origin (frequency polarization), in relation to the entire extension of the earth's surface and therefore taking into consideration the geographical areas of the terrestrial globe, from where such signals seem to come. the study of radio anomalies also allowed to show how there is a relationship between the seismic magnitude of the events recorded in the study period, and the quantity of radio-anomalies that appeared in the same temporal context figure 13. it is clear that the increase in the number of radio-anomalies recorded in a certain period raises the seismic magnitude of telluric events recorded in the himalayan area. this suggests that the greatest number of electromagnetic emissions can refer to a higher energy in accumulation, which then frees itself in the form of greater seismic magnitude. these data also say that we find ourselves within a system of laws governed by thermodynamics. the first principle of thermodynamics, also called, by extension: "law of conservation of energy", is a fundamental assumption of the theory of thermodynamics; it represents a formulation of the principle of conservation of energy and states that: "energy internal of an isolated thermodynamic system is constant". a thermodynamic universe, consisting of the system and its environment, is an isolated system. energy is neither created nor destroyed, but is transformed from one form to another: energy can be transferred through heat and labor exchanges. in the case of our study, the evidence of these statements is evident because the reference system that is energy in storage, seems to constantly change from one form to another, i.e. from mechanical energy, potential energy, electromagnetic energy and kinetic energy, to then return to the "zero principle" or to a thermodynamic equilibrium. this mechanism takes place continuously, and the emissions received by the rdf monitoring system indicate precisely such mechanisms. the greater the intensity and duration in minutes or hours, the greater the seismic magnitude observed. summarizing the discoveries made during the nine months of monitoring, it was possible to establish the following: 1. the greater the number of radio-anomalies and the greater the seismic magnitude of telluric events that occur in a given area indicated by the rdf system. 2. the lower the number of radio-anomalies and the lower the seismic magnitude that can be expected from the telluric events in a given area indicated by the rdf system. 3. the radio emissions detected by the rdf system of the radio emissions project have indicated precisely the geographical areas where earthquakes have occurred, with an error in azimuth (in degrees) that is greater for the most distant earthquakes and lower for those close to the monitoring station (in this case we speak of signal phase shift). 4. radio emissions with longer duration and amplitude, or simultaneous appearance on different frequencies of the band plumbed by the detection system have indicated more intense earthquakes than those preceded by less durable and less extensive increases in frequency that have always preceded earthquakes of lower magnitude. 5. normally, the electromagnetic increments highlighted by the monitoring system preceded strong seismic events even for several days. on average, this time difference reaches 20 hours. the important evidence of these data indicates how it is necessary to continue experimenting with this monitoring technique on a global scale. the indications provided by the rdf system developed by the radio emissions project confirm the working hypotheses advanced since 2017, when this monitoring technique was used for the first time. the ionospheric and solar interactions, according to what can be ascertained from the monitoring data, are correlated with the seismic phenomena on a global scale. this interaction has already been known for some time, through the observations and studies of the radio emissions project. again, this interaction was confirmed. the scientific evidence of pre-seismic electromagnetic emissions, coming from the area under monitoring, suggests that these phenomena are local and therefore generated precisely, as already mentioned, by crustal phenomena able to accumulate sufficient energy to determine earthquakes. intense. it is also clear that such emissions are deployed from precise areas whose azimuthal position does not differ very much in degrees from the azimuthal angle indicated by the monitoring system. this tells us therefore that this system is able to accurately indicate the areas of the planet where such signals come, suggesting in advance the area in which an earthquake will occur. asian review of environmental and earth sciences, 2019, 6(1): 16-27 20 © 2019 by the authors; licensee asian online journal publishing group figure-1. schematization of the rdf radio direction finding receiving and amplification system located in lariano, rome, italy; developed by the radio emissions project, and used for this study. it consists of two loop antennas, a radio amplifier (receiver), connected to the pc's microphone socket, via the sound blaster. source: radio emissions project, rome-italy. figure-2. the geographical area taken into consideration. source: google map. figure-3. the geographical area examined and the azimuth monitored by the rdf system of lariano, rome, italy and pontedera, pisa, italy. source: google map. asian review of environmental and earth sciences, 2019, 6(1): 16-27 21 © 2019 by the authors; licensee asian online journal publishing group figure-4. worldwide coverage of the rdf system, developed by daniele and gabriele cataldi. source: google earth. figure-5. distance between the rdf station of lariano, rome, italy and the himalayan area subject to monitoring. source: © google maps. figure-6. the radio-anomaly (turquoise signals) recorded from himalayan azimuth. in this case it is one of the spectrograms recorded by the rdf station in lariano, rome, italy. source: radio emissions project, rome-italy. asian review of environmental and earth sciences, 2019, 6(1): 16-27 22 © 2019 by the authors; licensee asian online journal publishing group figure-7. relationship between the number of electromagnetic anomalies that appeared during the monitored period of the study. source: radio emissions project, rome-italy. figure-8. relationship between electromagnetic frequency of the radio-anomalies appeared and their number in the period in which this study continued. source: radio emissions project, rome-italy. figure-9. number of radio-anomalies and their distribution in the utc temporal context. source: radio emissions project, rome-italy. asian review of environmental and earth sciences, 2019, 6(1): 16-27 23 © 2019 by the authors; licensee asian online journal publishing group figure-10. distribution of radio-anomalies and their electromagnetic frequency. as can be seen, most of these include the whole electromagnetic band considered. source: radio emissions project, rome-italy. figure-11. distribution of radio-frequency anomalies. as it is visible the largest percentage is the one with a send width of 32000 hz. source: radio emissions project, rome-italy. figure-12. distribution of the number of earthquakes, which appeared in the himalayan area examined by the study and their magnitude. source: usgs asian review of environmental and earth sciences, 2019, 6(1): 16-27 24 © 2019 by the authors; licensee asian online journal publishing group figure-13. relationship between the number of radio-anomalies appeared during the study (by the radio emissions project) and the number of earthquakes appeared in the same period, with magnitude m 2.5+ (by usgs). source: usgs and radio emissions project, rome-italy. graph-1. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area april 2018. source: radio emissions project, rome-italy and usgs. graph-2. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area may 2018. source: radio emissions project, rome-italy and usgs. asian review of environmental and earth sciences, 2019, 6(1): 16-27 25 © 2019 by the authors; licensee asian online journal publishing group graph-3. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area june 2018. source: radio emissions project, rome-italy and usgs. graph-4. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area july 2018. source: radio emissions project, rome-italy and usgs. graph-5. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area august 2018. source: radio emissions project, rome-italy and usgs. asian review of environmental and earth sciences, 2019, 6(1): 16-27 26 © 2019 by the authors; licensee asian online journal publishing group graph-6. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area september 2018. source: radio emissions project, rome-italy and usgs. graph-7. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area october 2018. source: radio emissions project, rome-italy and usgs. graph-8. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area november 2018. source: radio emissions project, rome-italy and usgs. asian review of environmental and earth sciences, 2019, 6(1): 16-27 27 © 2019 by the authors; licensee asian online journal publishing group graph-9. relationship between the frequency variation of the recorded electromagnetic signals and the seismic magnitude of the events occurring in the himalayan area december 2018. source: radio emissions project, rome-italy and usgs. references [1] r. bilham, v. k. gaur, and p. molnar, "himalayan seismic hazard," science, vol. 293, pp. 1442-1444, 2001. available at: https://doi.org/10.1126/science.1062584. [2] v. straser, d. cataldi, and g. cataldi, "radio direction finding system, a new perspective for global crust diagnosis," new concepts in global tectonics journal, vol. 6, pp. 203-211, 2018. [3] v. straser¹, g. cataldi, and d. cataldi, "seismic signals detected in italy before the nikol'skoye (off kamchatka) earthquake in july 2017," ncgt journal, vol. 5, pp. 391-396, 2017. [4] v. straser, g. cataldi, and d. cataldi, "radio-anomalies: a tool for earthquake and tsunami forecasts," presented at the european geosciences union (egu) general assembly 2015, natural hazard section (nh5.1), sea & ocean hazard tsunami, geophysical research abstract, vienna, austria. harvard-smithsonian center for astrophysics, high energy astrophysics division, sao/nasa astrophysics data system, 2015. [5] g. cataldi, d. cataldi, r. rossi, and v. straser, "self-elf electromagnetic signals correlated to m5+ italian earthquakes occurred on august 24, 2016 and january 18, 2017," ncgt journal, vol. 5, pp. 134-143, 2016. [6] d. cataldi, g. cataldi, and v. straser, "self and vlf electromagnetic emissions that preceded the m6. 2 central italy earthquake occurred on august 24, 2016," presented at the egu general assembly conference abstracts, 2017. [7] g. cataldi, d. cataldi, and v. straser, "solar and geomagnetic activity variations correlated to italian m6+ earthquakes occurred in 2016," in egu general assembly conference abstracts, 2017, p. 3681. [8] d. r. choi and j. l. casey, "new madrid seismic zone, central usa: the great 1811-12 earthquakes, their relationship to solar cycles, and tectonic settings," global climate status report, 1-2015. space and science research corporation2015. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 15 asian review of environmental and earth sciences vol. 5, no. 1, 15-21, 2018 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.15.21 groundwater based irrigation and food security in raya-kobo valley, northern ethiopia dessie nedaw1 nata tadesse tafesse2  kifle woldearegay3 tesfamichael gebreyohannes4 frank van steenbergen5 loiskandl willibald6 ( corresponding author) 1school of earth sciences, addis ababa university, ethiopia 2department of geology, university of botswana, botswana 3,4department of earth sciences, mekelle university, ethiopia 5metameta, the netherlands 6institute of hydraulics and rural water management, boku, austria abstract the raya-kobo valley is characterized by good groundwater resources potential (excess of 198 mm3) located in northern ethiopia. the total area of the valley is approximated to be 3510 km2. despite this potential of groundwater, the area has been suffering from droughts. establishment and expansion of cooperative societies, small business enterprises and irrigation farming were given priority as interventions to address the food security problem in the valley. these interventions were designed and implemented in the last several years by the regional governments administrating the raya-kobo valley, and groundwater is used as a source of water for irrigation farming for more than nine to ten years. nevertheless, food insecurity is still a major problem in the area. the present study has been conducted to investigate the extent of contribution of the groundwater based intervention in the elimination food insecurity. the study was conducted by collecting, analyzing and interpreting all the existing relevant data of the study area. groundwater potential was compiled from the author‟s previous works and recently conducted research works. the impact of the groundwater based irrigation on food security issues was assessed using informal and formal interviews and focus group discussions. limited area coverage of the irrigated land and the long time taken for the extension works in those drilled productive wells are the major limitations in the kobo valley that makes the groundwater based irrigation unable to release the farmers of the area from the food insecurity. in raya valley, besides to these problems, absence of responsible office, failure of pump, and the long time taken for pump maintenance are also the major factors. in raya-kobo valley food security is highly related to the availability of water. irrigating the whole potential irrigable area, increasing and sustaining availability of groundwater and management of the irrigation scheme are vital to eradicate food insecurity from raya-kobo valley. keywords: confined aquifer, groundwater storage, government investments, northern ethiopia, unconfined aquifer. citation | dessie nedaw; nata tadesse tafesse; kifle woldearegay; tesfamichael gebreyohannes; frank van steenbergen; loiskandl willibald (2018). groundwater based irrigation and food security in raya-kobo valley, northern ethiopia. asian review of environmental and earth sciences, 5(1): 15-21. history: received: 19 june 2018 revised: 20 august 2018 accepted: 24 august 2018 published: 28 august 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group contribution/acknowledgement: all authors contributed to the conception and design of the study. funding: the research work was financed by the netherlands organization for scientific research (nwo), wotro science for global development under the programme cocoon vprcs/wotro/13/2011: groundwater in the political domain. moreover the write up is supported by the research grant from austrian agency for international mobility and cooperation in education, science and research. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ........................................................................................................................................................................................................... 16 2. methods .................................................................................................................................................................................................................. 19 3. results ..................................................................................................................................................................................................................... 19 4. discussions ............................................................................................................................................................................................................. 20 5. conclusions ............................................................................................................................................................................................................ 20 references ................................................................................................................................................................................................................... 21 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.15.21&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ http://asianonlinejournals.com/index.php/arees/article/view/705 https://orcid.org/0000-0002-4687-7540 http://asianonlinejournals.com/index.php/arees/article/view/705 https://orcid.org/0000-0002-4687-7540 http://asianonlinejournals.com/index.php/arees/article/view/705 https://orcid.org/0000-0002-4687-7540 asian review of environmental and earth sciences, 2018, 5(1): 15-21 16 1. introduction 1.1. general groundwater is that part of the hydrologic system that occurs in a geologic environment. it plays an important role in water supply, ecology and maintaining river flow. it comprises 97 percent of the world‟s readily accessible freshwater and provides the rural, urban, industrial and irrigation water supply needs of 2 billion people around the world [1]. as the more easily accessed surface water resources are already being used, pressure on groundwater is growing. compared to surface water, groundwater is likely to be much more compatible with a variable and changing climate. relative to surface water, aquifers have the capacity to store large volumes of water and are naturally buffered against seasonal changes in temperature and rainfall. they provide a significant opportunity to store excess water during high rainfall periods, to reduce evaporative losses and to protect water quality [2]. according to the ministry of water resources [3] ethiopia is endowed with huge natural water resources, which include 122 billion m3 annual surface runoff and 2.9 billion m3 of groundwater. however, the county‟s water resource has not contributed enough to the country‟s socio-economic development, because major part of the surface runoff is not utilized and at the same utilization of groundwater for irrigation is still in infantile stage. this study is conducted in both raya and kobo valleys in northern ethiopia, which are located in the tigray regional states and amhara regional state, respectively, having an area of about 3808 km2.the valleys are characterized by flat topography and experiences arid to semi-arid climatic conditions with highly erratic and unreliable rainfall. in both cases the main economic means is rain fed agriculture. among the northern parts of the country, the raya-kobo valley is one of the areas that are highly affected by frequent droughts. major climatic limitations for agricultural production are erratic rainfall, unpredictable monsoons, which often combined with intermittent dry spells that regularly threaten the survival of the crops, resulting in reduced production and food insecurity [4]. the infamous drought caused by very low rainfall (figure. 1) in 1984 had claimed thousand lives. raya-kobo valley is administrated by two regional states: tigray regional state and amhara regional state. the northern part, commonly called raya valley, is administrated by tigray regional state whereas the southern part, called kobo valley, administrated by amhara regional state. to improve the problems of food insecurity in this valley groundwater based irrigation was introduced to the respective administrative area of the valley by the respective regional governments before five years at different time. since then groundwater based irrigation become one of the activities in addition to rain fed agriculture. figure-1. annual rainfall distribution in selected meteorological stations in raya-kobo valley. groundwater based irrigation was commenced in raya valley in 2008 by the ministry of water resources currently called ministry of water, irrigation and energy. in kobo valley it was commenced by the regional government and run by kobo-girana valley development project since 2005 [5]. in both areas of the valley, this irrigation scheme was implemented with the aspiration of increasing food security and by then reducing the dependency on rain fed agriculture. at present, in both areas of the valley large numbers of groundwater structures, mainly deep wells, were drilled and still new groundwater developments are underway. following the drilling of boreholes, constructions of irrigation infrastructures are in progress, and small areas are covered by irrigation using functional boreholes, which are very few in numbers. those farmers who are involved in the irrigation schemes and their land covered by irrigation are cultivating different crops using complimentary and supplementary irrigation systems. even though groundwater based irrigation is there as intervention since five years ago, food insecurity is remain as a major issue in this valley without any significant improvements. groundwater based irrigation has not yet been able to play the major role in the agricultural production. a study that reveals the reason behind to this has not yet been done, which is the main objective of this study. the present study has been conducted to investigate the extent of contribution of the intervention in the elimination food insecurity and the reason why it is unable to boost agricultural productivity to the extent that enable it to play a major role in the agricultural production in this valley. asian review of environmental and earth sciences, 2018, 5(1): 15-21 17 1.2. location raya-kobo valley is located within utm 37p, 541000-59600m e and 1319000-1428000m n, and covers an area of 3510 km2 (figure. 2). raya valley has a total area of 2595 km2 whereas the remaining 915 km2 is constituted by kobo valley. 1.3. groundwater resource nearly 268 deep boreholes are inventoried in the study area. boreholes that are drilled mainly for irrigation purposes are 135 and 64 in raya valley and kobo valley, respectively. semi confined aquifer, confined aquifer and unconfined aquifer are the major aquifer types in raya-kobo valley. the depth of the boreholes ranges from 51 to 311m with an average depth of 148 m. the static water level ranges from artesian condition to 90m below ground surface with a mean value of 27 meter. the drawdown ranges from less than a meter to 63 meter with an average value of 15 meter. the well yield also ranges from 1.13 to 121 l/s with a mean value of 41 l/s. the general flow direction of the groundwater coincides with the surface water flow direction. generally the groundwater flow direction is from west to east (figure 3). basically the downstream upstream relationship is governed mainly by west to east flow. hydrogeologicallly there could be a hydraulic connection from north to south as the main aquifer is unconsolidated deposits. figure-2. location maps raya-kobo valley source: nata, et al. [6]. asian review of environmental and earth sciences, 2018, 5(1): 15-21 18 fig-3. digital elevation model, groundwater contours and flow line map of the study area. source: dessie [7]. 1.3.1. groundwater resource potential of raya valley the groundwater recharge, estimated by using water balance method, is 129.3 mcm (50 mm) per year [7]. the recharge occurs in all parts of the catchment based on availabilities of excess rainfall. the major portion of the recharge occurs on the plateau and the escarpments through direct (diffuse) infiltration. the escarpments due to their geomorphological setup, act as runoff zones rather than being water storage medium during rainy periods. limited infiltration can take place in the fractures of the rocks. fractures serve as an inlet for the rain fall in the escarpments. both runoff and the limited infiltrated water in the escarpments act as a source of replenishment for the aquifers that occur down in the topographically lower areas. a significant portion also recharged along the foot of the escarpment through indirect rainfall recharge from local surface runoff. from field observation and the general flow direction of the groundwater system the whole basin recharge is concentrated towards the valley fill material. reducing the amount used by the community on the plateau and escarpments which is estimated to be 5.731 mcm/year [8] the net groundwater recharge to the valley floor aquifer is found to be 123.6 mcm/year. this amount does not take into account the possible recharge that will occur because of irrigation as a return flow. the valley floor aquifers could yield theoretically about 123.6 mcm without adversely affecting the groundwater resource if all assumption for the calculation of the water balance is correct. the total yield of the wells (the sum of all the wells yield) which are already drilled and tested is 233.3 mcm. only few wells are operational currently. if all the wells are made operational and worked for eight months of the year for 12 hours then the total yield from the raya valley basin is estimated at 77 mcm. generally sustainable yield may not be equal to the conventional safe yield [9]. the future development of the wells should take into consideration the sustainable yield, which is less than the safe yield. the total groundwater storage was estimated by considering the total area of the valley floor, the saturated thickness and the storativity. accordingly the average thickness of the valley fill sediments is found to be 149 m and the average depth to the static water level is around 25 meter resulting in an average saturated thickness of 124 meter. if we assume a storativity of 0.003 for confined and semi confined aquifer which accounts about 70 % in the study area and a specific yield of 0.19 for unconfined aquifer which accounts 30 % of the study area [10] then the total groundwater storage for an area of 1018 km2 is about 7460 mcm. asian review of environmental and earth sciences, 2018, 5(1): 15-21 19 1.3.2. groundwater resource potential of kobo valley the annual dynamic groundwater potential in kobo valley as calculated using chloride mass balance method is 68.9 mcm [8]. similar to raya valley, the groundwater recharge is mainly concentrating in the alluvial deposit in the valley floor. recharge takes place in the same way with raya valley. the total number of wells extracting groundwater is not well known. it is difficult to know the planned or current groundwater abstraction to compare its impact on the sustainability. sixty four boreholes with a potential total yield of 74 mcm per year are inventoried but more were under construction during this research work. if we assume eight months operation for 12 hours a day the planned abstraction from the inventoried wells is equivalent to 24.6 mcm per year. the sustainable yield from this valley will be much higher as the major river is perennial and dependent on the groundwater discharge. the development of new irrigation well should take into account the possible negative impact on the surrounding surface water resources. the groundwater reserve for the alluvial aquifer in the kobo valley with areal coverage of 417 km2 comprising 70% confined and semi confined aquifer and 30% unconfined aquifer can be estimated by considering the storativity for confined aquifers to be 0.003 and specific yield for unconfined aquifer to be 0.19. the saturated thickness is estimated to be 95 meter. the total storage is 2331 mcm. 2. methods to achieve the above mentioned objective all the existing relevant primary and secondary data of the valleys were collected, analysed and interpreted. data that were generated in the previously done groundwater related activities were collected from different sources in addis ababa, alamata, mehoni and kobo (figure. 1) whereas first hand data were collected during the field investigation. field investigation and compilation of existing studies were used to estimate the groundwater resource of the area. the groundwater resource exploitation was assessed on field by direct communication with the farmers and the responsible district professionals. the impact of the groundwater based irrigation on food security issues was assessed using informal and formal interviews and focus group discussion with district administrators, woreda agriculture office, woreda food security office, woreda water offices, wuas (water user cooperative associations), individual farmers and by directly observing the living condition on the spot. furthermore, discussions were held with agriculture extension agents in the district (woreda is local name for district). 3. results 3.1. food security versus irrigation development in raya-kobo valley the study area comprises three districts, locally called “woreda”: alamata, raya azebo, and kobo. two of them, alamata and raya azebo, are in raya valley whereas the third one is in kobo valley. 3.2. kobo district (woreda) in this woreda, the potential irrigable area is about 20000 hectare. up to june 2012 a total of 64 deep wells have been drilled by governmental organization and investors for this purpose. out of these drilled wells 92.2 % was drilled by the governmental organization and the remaining 7.8 % was by investors. all the wells that were drilled by the investors are currently functional and used as a source of water for irrigation. in those wells that were drilled by governmental organization, however, only 28.8% of the drilled wells are functional and serving as a source of water for irrigation. for the remaining 71.2% the required works that make them to serve as a source of water are under construction. all the functional wells, both governmental and investors together, at present irrigating an area less than 1100 ha. around ten thousand people are benefiting from this intervention. the district has 41 smallest administrative units, locally called „kebeles‟, and all of them are found in the rural areas. even though the use of groundwater as source of water for irrigation was started since 2005, all these rural kebeles up to june 2012 are registered as food insecure. the safety net program which is designed as a social welfare for rural community registers families which are in need of support. for someone to be considered in safety net his annual productivity should be less than six months consumption. according to the statistical data collected from the food security office, out of the total population of 202262, 51550 peoples are supported by the productive safety net programme (psnp). the productive safety net programme (psnp) in ethiopia is aimed at enabling the rural poor facing chronic food insecurity to resist shocks, create assets and become food self-sufficient [11]. in the kobo valley, the productive safety net program (psnp) has two components: the direct support and public work components. in the direct support program those community members who are not able to work because of age and health condition are registered. accordingly, out of the total safety net beneficiaries, 5946 are in the direct support and the remaining 45604 are in the public work component. in the past years between 2008 and 2012, those farmers included in the irrigation schemes graduated from psnp are being certified as food secured. 3.3. raya valley alamata woreda in this area government led groundwater irrigation is there since 2008, only 6.9 per cent of the total drilled wells were utilized for this purpose till the end of 2012, and the remaining 93.1 were nonfunctional due to different reasons. even though the potential irrigable area in alamata is 16575 ha [12] up to the end of 2012, only 180 ha was developed through irrigation using these functional deep wells, and 588 peoples were benefited from this scheme. albeit an irrigable land of 1700ha is given to the investors, only 30 ha land is irrigated up to the end of 2012 using two deep wells. however, it is so slow, deep well groundwater irrigation has increased from less than 20.5 ha in the year 2008 to 210 ha in the year 2012. alamata has 14 rural kebeles and one rural town. all of them have peoples who are enlisted in the safety net program. there were 49990 beneficiaries in the safety net program at the initial stage. in the past years between asian review of environmental and earth sciences, 2018, 5(1): 15-21 20 2008 and 2012, 3794 households graduated from psnp because of the intervention of the groundwater based irrigation. 3.4. raya valley raya azebo woreda like alamata, government led groundwater based irrigation practice is there since 2008, only 5.4 % of the total drilled wells were served as a source of water for this purposes till the end of 2012, and the remaining 94.6% were nonfunctional due to different reasons. using these functional deep wells 92 ha were covered by irrigation and 144 peoples were benefited from this scheme. out of the 2128.35 ha given to the investors, 324.5 ha was utilized for irrigation using five deep wells till the end of 2012. the potential irrigable area in this part of the valley is about 19880 ha [11]. although, it is so sluggish, deep well groundwater irrigation has increased from 76.8 ha in the year 2008 to 416.5 ha in the year 2012. there are 20 kebeles in the woreda, and all of them are food insecure. the total population of the woreda is about 127000. out of these the total beneficiaries of the psnp at the initial stage was 64213. between 2008 and 2012, 4480 households graduated from psnp because of the intervention of the groundwater based irrigation. 4. discussions the agency/department managed, farmer-managed or the community managed schemes and public-beneficiary managed are the different management styles associated with government-led irrigation schemes [13]. with the exception of the very few areas that are owned by investors, in the study area the major groundwater irrigation schemes are government-led and are managed by the beneficiary farm households via their wuas (water user cooperative associations). each cooperative association is administered by irrigation committee which consists of five to seven executive members. in each cooperative 50 to 100 households are involved. even though utilization of groundwater for irrigation is implemented in raya-kobo valley before five years, the study area is still known as one of the food insecure area. this is mainly because the rain fed farming is still the one that plays the major role in the agricultural production. dependence on rain-fed agriculture not only reduces productivity but also greatly increases growth volatility of the agriculture sector and the vulnerability of the poor [13]. contrary to the huge land and groundwater resource potential, food insecurity is still the major problem in raya-kobo valley. in raya valley government is highly engaged in the development of groundwater. however, drilling of boreholes was not accompanied or immediately followed by the essential extension works, which makes the drilled boreholes being an active water sources for the purpose that they were drilled. because of these only 6.25% the total drilled boreholes were functional at the end of 2012 and the remaining 93.75% were found closed and idle. management of utilization of the groundwater, management of the functional boreholes and of the irrigation schemes are left to the farmers. as it was mentioned above farmers are managing all these by themselves as cooperatives. one of the major problems for the administrative body of the cooperatives is a breakdown of pump that happened sporadically here and there. lack of technical knowledge of the irrigation committee, lack or absence of immediate assistance from the concerned body, lack of immediate access to the technicians and lack of spare parts makes the repair services difficult and time consuming. as the maintenance duration takes more and more time the farmers will be forced to depend only on the rain fed agriculture and this exposed them to food insecurity since the rainfall is unreliable and erratic. frequent breakdown of motor pumps (scheme machinery) is a common problem in any irrigation scheme that use groundwater as source, and if it is not get an immediate solution it becomes a major problem to the sustainability of irrigation systems. this is a case of raya valley groundwater based irrigation scheme. absence of responsible governmental or government affiliated office in the management of utilization of the groundwater, management of the functional boreholes and of the irrigation schemes, the delay in the extension works on the drilled boreholes, failure of pump, and the long time taken for pump maintenance are the major factors that exert an obstacle to the proper implementation of groundwater based irrigation and its sustainability in raya valley. due to all these problems plus limited area coverage of the irrigation scheme, the groundwater based irrigation is not yet able to set the farmers free from food insecurity, which is highly related to the availability of water in the area. in kobo valley, unlike the raya valley, the cooperatives get full support from the regional government through an office called“kobo-girana valley development office”.the office was established with the aim of enhancing food security through irrigation development in the kobo-girana valleys, and it has been operating in the area since 1999 [6]. development of groundwater, management of functional boreholes, groundwater utilization and management of the irrigation scheme are all managed by this office. even though the office is there since 1999, the area covered by irrigation, excluding the area irrigated by investors (less than 520 ha), is less than 580 ha, which is less than 3% the potential irrigable area in the valley; indicating the sluggish rate of the implementation of the groundwater based irrigation in the area. moreover, the drilled boreholes are not used immediately after construction for the purpose they were drilled. the extension work is found taking more time than what is allocated for it. pump maintenance is not a problem to the cooperatives since it is handled by the office. consequently, sustainability is not an issue. in the kobo valley, even though, the presence of responsible office maintains sustainability of the irrigation systems, still the valley has peoples that are food insecure. this mainly attributed to the limited area coverage of the project as compared to the total irrigable land in the valley and the long time taken for the extension works in those drilled productive wells. 5. conclusions the groundwater resource potential of raya-kobo area is in excess of 198 mm3 as confirmed by several studies and subsequent drilling operations carried out in the past. there have been more studies than the implementation of projects. the main challenge revealed in this study is the failure to utilize this huge water resource potential due asian review of environmental and earth sciences, 2018, 5(1): 15-21 21 to various reasons to alleviate poverty by reducing the number of population dependent on the safety net. as a result, food security and livelihood improvement still remains as a major problem. absence of responsible office, the very long duration taken for the extension works, failure of pump, and the long time taken for pump maintenance are the major factors that exert an obstacle to the proper implementation of groundwater based irrigation and its sustainability in raya valley. due to all these problems plus limited area coverage of the irrigation scheme, the groundwater based irrigation is not yet able to set the farmers free from food insecurity. limited area coverage of the project as compared to the total irrigable land in the valley and the long time taken for the extension works in those drilled productive wells are the major limitations in the kobo valley that makes the groundwater based irrigation unable to release the farmers of the area from the food insecurity. in raya-kobo valley food security is highly related to the availability of water. therefore, increasing the availability of groundwater to the users and maintaining sustainability of the irrigation scheme are highly indispensable in successfully transferring the beneficiaries of safety net to become food self-sufficient. references [1] g. héctor, r. saleem, s. buba, t. albert, and d. richard, "india groundwater governance case study," water papers (washington, dc), papers no. 71727, p. 64, 2011. [2] c. craig, e. rick, h. susan, h. rafik, p. gabrielle, and p. carolina, "water and climate change: impacts on groundwater resources and adaptations," water working notes, water sector board of the sustainable development network of the world bank group, note no. 25, p. 75, 2010. [3] ministry of water resources, water sector development program 2002-2016 report. addis ababa, ethiopia: federal democratic republic of ethiopia, ministry of water resources, 2002. [4] t. nata and k. bheemalingeswara, "prospects and constraints of household irrigation practices, hayelom watershed, tigray, northern ethiopia," momona ethiopian journal of science, vol. 2, pp. 86 – 109, 2010. view at google scholar | view at publisher [5] abrham melesse endalamaw, "optimum utilization of groundwater in kobo valley, eastern amhara, ethiopia," a thesis presented to the faculty of the graduate school of cornell university, in partial fulfillment of the requirements for the degree of master of professional studies (mps), 2009. [6] t. nata, n. dessie, w. kifle, g. tesfamichael, and v. s. frank, "groundwater management for irrigation in the raya and kobo valleys, northern ethiopia," international journal of earth sciences and engineering, vol. 08, pp. 1104-1114, 2015. view at google scholar [7] n. dessie, "aquifer characterization and hydrochemical investigation of raya valley, northern ethiopia," ph.d. dissertation, institutes of applied geology, university of natural resources and applied life sciences (boku)vienna, vienna, 2003. [8] m. sileshi, hydrogeology, hydrogeochemistry and isotope hydrology of raya and kobo valleys, adjacent plateau, escarpment and part of afar rift, ethiopia: hydrogeological mapping, recharge evaluation and water quality assessment. addis ababa: ministry of mines and energy, geological survey of ethiopia, 2007. [9] m. sophocleous, "from safe yield to sustainable development of water resource the kansas experience," journal of hydrology, vol. 235, pp. 27–43, 2000. view at google scholar | view at publisher [10] g. h. afework, "aquifer characterization of the raya valley based on pumping test and geophysical data analysis," msc thesis, department of earth science, addis ababa university, addis ababa, 2010. [11] world food programme (wfp), ethiopia productive safety net programme (psnp). rome: psnp factsheet, world food programme, 2012. [12] water works design and supervision enterprise, engineering final feasibility study report. addis ababa: raya pressurized irrigation project, ministry of water resources, 2008. [13] y. muleta, "groundwater irrigation development and sustainability in raya valley northern ethiopia," journal of poverty, investment and development, vol. 16, pp. 67 – 83, 2015. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=prospects%20and%20constraints%20of%20household%20irrigation%20practices,%20hayelom%20watershed,%20tigray,%20northern%20ethiopia http://dx.doi.org/10.4314/mejs.v2i2.57676 https://scholar.google.com/scholar?hl=en&q=groundwater%20management%20for%20irrigation%20in%20the%20raya%20and%20kobo%20valleys,%20northern%20ethiopia https://scholar.google.com/scholar?hl=en&q=from%20safe%20yield%20to%20sustainable%20development%20of%20water%20resource%20-%20the%20kansas%20experience http://dx.doi.org/10.1016/s0022-1694(00)00263-8 1 © 2025 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 12, no. 1, 1-5, 2025 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v12i1.6368 © 2025 by the authors; licensee asian online journal publishing group effects of photovoltaic power plants connected to the grid from 2016 to 2022 in senegal on carbon dioxide emissions mamadou traore1,2 amadou sidibe1 saliou bolarinwa ogou1,3 alphousseyni ndiaye2 senghane mbodji4 ( corresponding author) 1departement of physics, university of julius nyéréré of kankan, guinea. 1email: mamadou.traore@uadb.edu.sn 1email: asidibe76@yahoo.fr 2research team energetic system and efficiency, department of physics, alioune diop university of bambey, bambey, senegal. 2email: aphousseyni.ndiaye@uadb.edu.sn 3département de physique (fast) et institut des mathématiques et de sciences physiques, université d’abomeycalavi, 01 bp 613, porto-novo, bénin. 3email: salogoub@gmail.com 4research team in renewable energies, materials and laser of department of physics, alioune diop university of bambey, bambey, senegal. 4email: seghane.mbodji@uadb.edu.sn abstract the use of fossil fuels for energy production has caused global warming, the main environmental concern of our society. today, renewable energy sources offer a solution to this problem, and the government of senegal is working to promote the renewable energy sector in order to combat global warming and produce reliable, affordable, and sustainable energy. the current work seeks to study the contribution of photovoltaic power plants to the reduction of greenhouse gas emissions, particularly carbon dioxide. photovoltaic system operation, depending on atmospheric parameters, utilizes the retscreen software to collect weather data such as ambient temperature, irradiation, and wind velocity for each location. mathematical equations modeling the temperature, efficiency, and power of a photovoltaic module are used in this work to determine the influence of atmospheric conditions on solar power plants. the results showed that weather parameters have a significant influence on energy production. the results also demonstrated senegal’s contribution to the reduction of greenhouse gases with 194.228 megawatts (mw) of solar photovoltaic plants. this contribution consisted of injecting 364.746 gigawatt-hours (gwh) of clean energy per year, i.e., 7294.920 gwh over 20 years, and in reducing 314,411.1 tons of carbon dioxide per year, i.e., 62,288,222 tons over 20 years. keywords: co2 reduction, greenhouse gas, global warming, renewables energies, photovoltaic power plants, senegal. citation | traore, m., sidibe, a., ogou, s. b., ndiaye, a., & mbodji, s. (2025). effects of photovoltaic power plants connected to the grid from 2016 to 2022 in senegal on carbon dioxide emissions. asian review of environmental and earth sciences, 12(1), 1–5. 10.20448/arees.v12i1.6368 history: received: 16 december 2024 revised: 20 january 2025 accepted: 30 january 2025 published: 6 february 2025 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. institutional review board statement: not applicable. transparency: the authors state that the manuscript is honest, truthful, and transparent, that no key aspects of the investigation have been omitted, and that any differences from the study as planned have been clarified. this study followed all writing ethics. competing interests: the authors declare that they have no competing interests. authors’ contributions: all authors contributed equally to the conception and design of the study. all authors have read and agreed to the published version of the manuscript. contents 1. introduction ......................................................................................................................................................................................... 2 2. presentation of the sites and methodology .................................................................................................................................. 2 3. results and discussion ...................................................................................................................................................................... 3 4. conclusion ............................................................................................................................................................................................ 5 references ................................................................................................................................................................................................. 5 mailto:mamadou.traore@uadb.edu.sn mailto:asidibe76@yahoo.fr mailto:aphousseyni.ndiaye@uadb.edu.sn mailto:salogoub@gmail.com mailto:seghane.mbodji@uadb.edu.sn https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v12i1.6368 https://orcid.org/0000-0002-6383-8690 https://orcid.org/0009-0009-3618-1011 https://orcid.org/0000-0001-6839-8703 https://orcid.org/0000-0003-4024-4256 https://orcid.org/0000-0001-7235-5036 asian review of environmental and earth sciences, 2025, 12(1): 1-5 2 © 2025 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this work is the first scientific study carried out in senegal to determine the amount of carbon dioxide that photovoltaics power plants will reduce in 20 years' time. this work determines the influence of atmospheric conditions on installed photovoltaic power plants. 1. introduction in 2017, out of 357 million people living in the economic community of west african states (ecowas) region, 171 million were without electricity [1]. a large part of the energy produced in this region comes from fossil fuels. the combustion of fossil fuels emits greenhouse gases, thus increasing global warming. therefore, the energy transition (from fossil energies to renewable energies) is still topical issue. in 2015, an agreement was signed in paris (at cop21). such an agreement aims at reducing the rate of carbon emissions worldwide to such an extent that the global average temperature should not exceed 2°c (and even 1.5°c) above preindustrial levels for this century [26]. this situation provides a favorable ground for the use of renewable energies which is becoming increasingly one of the major focuses of the world's population. the most widespread renewable energies are biomass, hydroelectricity, wind and solar energies. in africa, many actors such as states and organizations impact the energy transition [7]. in this logic, ecowas countries will invest about €1.773 million in photovoltaic (pv) solar energy before 2030 [3, 8]. it is important to note that in west africa, the daily average solar radiation is 5-6k𝑊 ℎ/𝑚2/𝑑𝑎𝑦 [3]. in addition, the source of this energy is available everywhere in sub-saharan africa [9]. in recent decades, it has been noted that solar pv has undergone very significant development [10]. senegal, for example, has been developing reform policies in the energy sector since 2010, particularly in the area of green (renewable) energy [11]. senegal is a west african country which is located at latitude 14°43’29 north, longitude 17°28’24 west with a total area of about 196,700 km2, and a population of over 15 million people. the institute of meteorological physics (imp) is the first institute of solar energy research. it was established at the university of cheikh anta diop of dakar in 1962 and was renamed centre for studies and research on renewable energies (csrre) in 1975 [12]. in senegal, 60% of the population are rural residents, and only 40% of people living in rural areas have access to electricity. the connection of solar photovoltaic plants will enable the country to reduce its electricity imports still further by up to 15% [1]. between 2016 and 2022, the senegalese government installed eight photovoltaic solar power plants connected to the grid. these include bokhol, malicounda, tène merina, sakal, diass, santhiou mekhe and kahone. these green power generation systems will help to reduce greenhouse gas emissions knowing that every kwh produced corresponds to a reduction in the use of fossil fuels. however, there is no scientific research to determine the quantity of carbon dioxide that can be saved by these solar power plants. the aim of this work is to study the effect of these pv power plants on carbon dioxide emissions, one of the greenhouse gases, considering meteorological parameters such as temperature, solar irradiation and wind speed. to achieve this aim, the current paper is organized as follows: the pv solar plant sites and the methodology will be described in section 2, starting with a presentation of senegal’s pv solar potential. the results obtained from the methodology will be presented and discussed in section 3. the last section of this paper is the conclusion. 2. presentation of the sites and methodology in this section, we will present the map of senegal’s solar potential and the sites where photovoltaic power plants are installed, and develop the methodology used. 2.1. photovoltaic solar potential in senegal figure 1 shows a map of senegal and the corresponding solar potential. it can be seen that certain areas of saintlouis, louga and fatick regions and the entire dakar region have the highest solar potential in senegal, at over 4.8 kwh/kwp. in fact, the eight power plants studied in this research work are located in above-mentioned regions. the least unfavorable areas are in the regions of tambacounda, kédougou, kolda and ziguinchor. figure 1. photovoltaic power potential in senegal. source: abdoulaye, et al. [13]. asian review of environmental and earth sciences, 2025, 12(1): 1-5 3 © 2025 by the authors; licensee asian online journal publishing group 2.2. locations for pv power plants bokhol, in the saint-louis region, is the first solar photovoltaic power plant in senegal or even in west africa. saint-louis is located at latitude 16.05° n and longitude -16.45° e. our second solar power plant is located in kahone. kahone was a town in the fatick region before being classified in the kaolack region of senegal. the geographical coordinates are: latitude 14°13 n and longitude -16°07 e. the third pv power plant in this study is located in sakal. sakal is located 27 km from louga, with geographical coordinates of 15°62 n latitude and -16°22 e longitude. the solar power plant is located 3 km from sakal. finally, the diass, malicounda, ten merina and santhiou methe power plants are located in the thies region, where the geographical coordinates are 14°38’21 n and 17°5’16 w. 2.3. methodology the efficiency of a pv module in the laboratory is low. it is 0.1575 for the solar modules installed in the power plants studied in this work. when the pv module is in operation, its efficiency depends on the temperature and irradiation of the installation site. equation 1 gives the efficiency of a photovoltaic panel [14]. 𝑟𝑃𝑉 = 𝑟𝑆𝑇𝐶 (1 − 𝑎(𝑇𝑃𝑉 − 𝑇𝑟𝑒𝑓) + 𝑏. 𝑙𝑛 ( 𝐺𝑚 1000 )) (1) where: • 𝑟𝑆𝑇𝐶 is the module efficiency under standard conditions, i.e 𝑇𝑃𝑉=𝑇𝑟𝑒𝑓 = 25˚c, 𝐺𝑚 = 1000 w/m2 and air density =1.5; • 𝑇𝑟𝑒𝑓 is the reference temperature; • 𝐺𝑚 is the irradiation of the area where the module is installed; • 𝑇𝑃𝑉 is the module temperature, 𝑎 is the temperature coefficient and is equal to -0.0045 and 𝑏, the solar irradiation coefficient, is equal to 0.11. the temperature of the pv noted 𝑇𝑃𝑉 varies according to weather conditions. in this study, we will use the mathematical equation 2 modelling temperature as a function of ambient temperature, irradiation and wind speed. 𝑇𝑃𝑉 = 𝑇𝑎𝑚 + 𝐺𝑚 (𝐶1+𝐶2.𝑣𝑠) (2) where: • 𝑇𝑎𝑚 is the ambient temperature; • 𝑣𝑠 is the wind speed; • 𝐶1and 𝐶2 are empirical coefficients whose values are respectively equal to 32.12 w/(˚cm2) et 4.51 ws/(˚cm3). the output power of a pv solar module noted 𝑃𝑆_𝑃𝑉 is modelled by equation 3, which shows its dependence on variations in weather conditions. 𝑃𝑆_𝑃𝑉 = 𝑃𝑃𝑉_𝑆𝑇𝐶 .𝐺𝑚.𝑟𝑃𝑉 1000.𝑟𝑆𝑇𝐶 (3) where: 𝑃𝑃𝑉_𝑆𝑇𝐶 is the peak power of the module. the pv temperature is calculated from equation 2, the result of which will be used to find the pv efficiency given by equation 1. the objective is to determine the quantity of carbon dioxide (𝐶𝑂2), one of the greenhouse gases, that can be reduced by the four proposed pv power plants. to calculate the quantity reduced by each pv plant, equation 4 is proposed [15]. 𝑄𝐶𝑂2 (𝑟𝑒𝑑𝑢) = 𝐹𝑒𝑚. 𝐸𝑔𝑟𝑖𝑑 = 0.862 ∗ 𝐸𝑔𝑟𝑖𝑑 (4) where: 𝐸𝑔𝑟𝑖𝑑 is the energy generated by the pv module that is expressed in mwh, 𝐹𝑒𝑚 is the greenhouse gas emission factor, whose value is equal to 0.862 kgco2/kwh or 0.862 tco2/mwh for senegal. this value is given by the retscreen software. 𝐸𝑔𝑟𝑖𝑑 is calculated by equation 5: 𝐸𝑔𝑟𝑖𝑑 = 𝑃𝑆_𝑃𝑉 . 𝑡(ℎ) (5) where t(h) is the pv operating time in hours, i.e. 360 hours per month or 12 hours per day in senegal. 3. results and discussion in this section, the meteorological data obtained using the retscreen software are used to determine the temperatures, efficiencies and output powers of the pv modules. the ambient temperatures, wind speeds and module temperatures are shown in figure 2, 3 and 4. these characteristics are not represented for the malicounda, ten merina and santhiou mekhe sites, as these sites are in the same geographical area as diass. figure 2. variation of the ambient temperature at pv power plant sites over the year. asian review of environmental and earth sciences, 2025, 12(1): 1-5 4 © 2025 by the authors; licensee asian online journal publishing group figure 2 shows the ambient temperatures at the sites of the four power stations. the figure shows that the town of kahone has the highest temperature every month, followed by the town of sakal. diass has the lowest temperature. figure 3 shows the different wind speeds. it can be seen that, contrary to the temperature, kahone and sakal have respectively the lowest and highest wind speeds. after sakal, diass comes second, followed by bokhol. figure 3. variation of wind speed at pv power plant sites over the year. using the results shown in figure 2 & 3, the pv module temperatures for four pv power plants are determined and illustrated in figure 4. this shows that the monthly temperatures of the modules are higher than those of the environment in which they are installed. at kohone, the temperature can exceed 40°c. this may be due to the low wind speed. diass had the lowest module temperatures. these results confirm the dependence of pv panel temperature on wind speed and ambient temperature. figure 4. variation of the pv module temperature over the year. table 1 represents the pv module efficiencies of the four pv solar power plants. this table shows that the modules installed at bokhol have a higher efficiency than the other sites, except in june when sakal has a slightly higher efficiency. this can be explained by the fact that the wind speed in june is higher at sakal than bokhol. table 1. the pv module efficiencies of the four pv solar power plants. january 0.1462 0.1441 0.1439 0.1418 february 0.1489 0.1481 0.1466 0.1462 march 0.1539 0.1510 0.1502 0.1499 april 0.1551 0.1522 0.1516 0.1525 may 0.1551 0.1530 0.1527 0.1538 june 0.1541 0.1536 0.1529 0.1543 july 0.1551 0.1524 0.1527 0.1531 august 0.1559 0.1516 0.1518 0.1530 september 0.1547 0.1519 0.1516 0.1531 october 0.1539 0.1512 0.1507 0.1524 november 0.1493 0.1466 0.1469 0.1472 december 0.1458 0.1423 0.1423 0.1430 sites bokhol diass kahone sakal asian review of environmental and earth sciences, 2025, 12(1): 1-5 5 © 2025 by the authors; licensee asian online journal publishing group table 2 shows the power output, energy injected into the grid and quantities of co2 reduced per year. these 8 plants will enable 364.746 gwh to be fed into the grid every year, i.e. 7294.920 gwh over 20 years. after all, a solar power plant can operate for at least 20 years. in terms of contribution to the reduction of carbon dioxide emissions, 314411.1 tons will be reduced per year, i.e. 62288222 tons over 20 years. table 2. energy injected (mwh) to grid & quantity of co2 reduced (tons) in year. solar power plant power (w) energy injected (mwh) in year quantity of co2 reduced (tons) in year bokhol 20 32965.5 28416.3 diass 17 34914.6 30096.4 kahone 1 21.228 31059.5 26773.3 kahone 2 35 70371.1 60659.8 sakal 20 29077.5 25064.8 ten merina 29.5 60587.1 52226.1 santhiou mekhe 29.5 60587.1 52226.1 malicounda 22 45183.6 38948.3 total 194.228 364746 314411.1 4. conclusion the effect of photovoltaic power plants installed in senegal on carbon dioxide emissions has been studied in this work. instead of taking the value of installed power directly to calculate the quantity of 𝐶𝑂2 reduced, mathematical equations are used to find a more accurate quantity. this approach allowed us to determine the quantity of 𝐶𝑂2 reduced per year and to see the influence of meteorological parameters on the energy produced by pv power plants. in the future, the use of experimental values will enable a good estimate of reduced 𝐶𝑂2 to be made. references [1] o. adeoye and c. spataru, "quantifying the integration of renewable energy sources in west africa's interconnected electricity network," renewable and sustainable energy reviews, vol. 120, p. 109647, 2020. https://doi.org/10.1016/j.rser.2019.109647 [2] j. delbeke and p. vis, towards a climate-neutral europe: curbing the trend, 1st ed. london: routledge, 2019, p. 24. [3] w. sawadogo, b. j. abiodun, and e. c. okogbue, "impacts of global warming on photovoltaic power generation over west africa," renewable energy, vol. 151, pp. 263-277, 2020. [4] k. sudhakar, w. ngui, and i. kirpichnikova, "energy analysis of utility-scale pv plant in the rain-dominated tropical monsoon climates," case studies in thermal engineering, vol. 26, p. 101123, 2021. [5] j. m. gremmelspacher, r. c. pizarro, m. van jaarsveld, h. davidsson, and d. johansson, "historical building renovation and pv optimisation towards netzeb in sweden," solar energy, vol. 223, pp. 248-260, 2021. https://doi.org/10.1016/j.solener.2021.02.067 [6] l. medef, a. saoudite, and c. m., "drian, climate negotiations issues for cop 27 (6-18/11) and expectations of medef," vol. 27, retrieved: https://www.medef63.fr/wp-content/uploads/2022/11/cop27-enjeux-pour-le-medef.pdf. 2015. [7] f. müller, s. claar, m. neumann, and c. elsner, "is green a pan-african colour? mapping african renewable energy policies and transitions in 34 countries," energy research & social science, vol. 68, p. 101551, 2020. https://doi.org/10.1016/j.erss.2020.101551 [8] ecreee, "ecowas renewable energy policy," retrieved: http://www.ecreee.org. 2015. [9] x. s. musonye, b. davíðsdóttir, r. kristjánsson, e. i. ásgeirsson, and h. stefánsson, "integrated energy systems’ modeling studies for sub-saharan africa: a scoping review," renewable and sustainable energy reviews, vol. 128, p. 109915, 2020. https://doi.org/10.1016/j.rser.2020.109915 [10] b. diouf and c. avis, "the potential of li-ion batteries in ecowas solar home systems," journal of energy storage, vol. 22, pp. 295301, 2019. https://doi.org/10.1016/j.est.2019.02.021 [11] a. s. ba, "the energy policy of the republic of senegal. pp. 12," retrieved: https://hal.science/hal-01956187v1. 2018. [12] i. youm, j. sarr, m. sall, and m. kane, "renewable energy activities in senegal: a review," renewable and sustainable energy reviews, vol. 4, no. 1, pp. 75-89, 2000. https://doi.org/10.1016/s1364-0321(99)00009-x [13] m. a. abdoulaye, g. j. p. tevi, d. diouf, and a. s. maiga, "impact of the intermittency of photovoltaic power plants on the frequency management: case of the senegalese electricity grid," journal of power and energy engineering, vol. 8, no. 07, p. 55, 2020. https://doi.org/10.4236/jpee.2020.87005 [14] e. kaplani and s. kaplanis, "thermal modelling and experimental assessment of the dependence of pv module temperature on wind velocity and direction , module orientation and inclination," solar energy, vol. 107, pp. 443–460, 2014. http://dx.doi.org/10.1016/j.solener.2014.05.037 [15] a. kowsar, f. naima, m. t. rana, n. haque, and f. alam, "techno-economic study of a photovoltaic power plant besides the railway track for rural uses in bangladesh," e-prime-advances in electrical engineering, electronics and energy, vol. 5, p. 100229, 2023. https://doi.org/10.1016/j.prime.2023.100229 asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://doi.org/10.1016/j.rser.2019.109647 https://doi.org/10.1016/j.solener.2021.02.067 https://www.medef63.fr/wp-content/uploads/2022/11/cop27-enjeux-pour-le-medef.pdf https://doi.org/10.1016/j.erss.2020.101551 http://www.ecreee.org/ https://doi.org/10.1016/j.rser.2020.109915 https://doi.org/10.1016/j.est.2019.02.021 https://hal.science/hal-01956187v1 https://doi.org/10.1016/s1364-0321(99)00009-x https://doi.org/10.4236/jpee.2020.87005 http://dx.doi.org/10.1016/j.solener.2014.05.037 https://doi.org/10.1016/j.prime.2023.100229 62 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 62-67, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.62.67 © 2021 by the authors; licensee asian online journal publishing group some physicochemical properties of soils from three steel welding and fabrication workshops in port harcourt, rivers state, nigeria edori, e. s1 edori, o. s2 bekee, d3 ( corresponding author) 1,2department of chemistry, ignatius ajuru university of education rumuolumeni, port harcourt, rivers state, nigeria. 2email: enizeedori@yahoo.com 3department of chemistry, rivers state university, port harcourt, rivers state, nigeria. abstract some physicochemical properties were assessed in soils within steel welding and fabrication workshops in port harcourt, rivers state, nigeria. the study was carried out between may to november, 2020. the physicochemical parameters were determined using standard conventional methods of analysis to ascertain the different levels of the selected physicochemical parameters in the studied environment. the results obtained within the months revealed that ph average range was between 6.8±0.08-7.1±0.05, the electrical conductivity average range was between 65.25±0.83-76±0.71µs/cm, percentage organic carbon was within average range of 0.396±0.0010.525±0.001%, percentage soil organic matter was in the average range of 0.682±0.0020.904±0.002% and for particle size analysis, percentage sand was in the average range of 75±0.7179±0.71%, percentage clay was in the average range 9.25±0.83-11±0.71% and percentage silt was in the average range 10.75±0.43-14±0.71% for the egbelu, elioparanwo and saint john soils respectively. observation from the nature of occurrence of the physicochemical parameters in the steel-welding and fabrication workshops showed that that the steel-welding and fabrication has not yet influenced the level of the physicochemical parameters in the soils studied. keywords: contamination, physicochemical properties, pollution, soil, welding, fabrication. citation | edori, e. s; edori, o. s; bekee, d (2021). some physicochemical properties of soils from three steel welding and fabrication workshops in port harcourt, rivers state, nigeria. asian review of environmental and earth sciences, 8(1): 62-67. history: received: 4 october 2021 revised: 26 october 2021 accepted: 18 november 2021 published: 8 december 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 63 2. materials and methods ................................................................................................................................................................... 63 3. results and discussion ................................................................................................................................................................... 64 4. conclusion ......................................................................................................................................................................................... 66 references .............................................................................................................................................................................................. 66 mailto:enizeedori@yahoo.com http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.doi.org/10.20448/journal.506.2021.81.62.67 https://orcid.org/0000-0002-0092-054x https://www.doi.org/10.20448/journal.506.2021.81.62.67 https://orcid.org/0000-0002-0092-054x https://www.doi.org/10.20448/journal.506.2021.81.62.67 https://orcid.org/0000-0002-0092-054x asian review of environmental and earth sciences, 2021, 8(1): 62-67 63 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature some physicochemical properties were assessed in soils within steel welding and fabrication workshops in port harcourt, rivers state, nigeria. 1. introduction the soil is a natural resource and the most useful in the support for production of food for humans due to its importance in agriculture. the soil is important in its constituents and through it, the basic need of food is actualized in the life of man and other living creatures. the soil provides the basic support for agricultural systems and production [1, 2]. enhancing productivity require the maintenance of the ecosystem which rely on the soil than any other resource and the physicochemical nature, characteristics and biological content of the soil are very important aspects in agricultural productivity [3-5]. the soil is composed of several minerals, broken rocks and organic constituents that have resulted in the alteration of reactions in the environment [6, 7]. the various contaminants and pollutants naturally are absorbed by the soil, no matter the quantity, this has made the soil to become a natural sink to all pollutants. this has resulted in changes in the chemical and physical characteristics of the soil. the ability of the soil to remove impurities, absorb oxygen, destroy disease causing agents and releasing carbon dioxide to the atmosphere has made it a natural purifier [7]. anthropogenic influence and certain other factors like vegetation, parent rocks and altitude of the given environment can change the physicochemical characteristics of the soil, such as ph, soil texture, particle size, electrical conductivity, total organic carbon, cation exchange capacity and moisture content [8]. the mobilization/immobilization and the redistribution of available nutrients in the soil depends on the physicochemical properties of the soil such as ph, organic matter, redox conditions and quantity of clay that will mobilize and transmit the nutrient elements and water to plants and through the food chain toto animals and humans [9]. human activities have led to increased contamination of the soil, such contamination/pollution has resulted in life challenges that threatens the existence of humans’, animals’ and plants’ life. anthropogenic activities such as application of pesticides and fertilizers, mining, discharge of industrial wastes, rupture of storage tanks and manufacturing of goods [10] has resulted in the physical and chemical changes of the natural soil of the environments. the contamination of the soil help in the blocking of air that diffuses the pores of the soil particles [11] and creates changes in the physical nature of the soil by altering the permeability and atterberg limits [1214]. the growth and development of plants and soil organisms are affected due to the changes in the chemical nature of the soil, such as ph, mineral nutrients and total organic carbon [15-17]. the continuous deprivation of these requirements is detrimental and produces grievous consequences that leads to inappropriate soil conditions thereby resulting in poor crop growth. this research work aimed at investigating the concentration of some physicochemical parameters of soil within the vicinities of two steel-welding and fabrication workshops in port harcourt, rivers state, nigeria. 2. materials and methods 2.1. collection and preparation of samples soil samples were collected within the vicinities of three steel welding and fabrication workshops in port harcourt. soil samples were collected at random between 0.00-30 cm depth with the help of soil auger. at each location, the samples where thoroughly mixed together to give a bulk composite sample. the soil samples were then put into a prepared polythene bag that was previously sterilized with the aid of a sterilized spatula and then transported to the laboratory for further preparations. the samples were dried to constant weight and the macerated to powder using mortar and pestle. a 2mm mesh was used to sieve the homogenizing soil samples after larger particles like stones have been removed and the samples properly labelled and designated according to their source. the parameters investigated were measured three times and the average value recorded. samples were collected within the space of eight months at interval of two months. 2.2. determination of ph and electrical conductivity the method of bamgbose, et al. [18] was used in the determination of the ph of the soil. 10 g of soil samples previously air dried was weighed into a 100 ml beaker then distilled water of 200 ml volume was added to the soil in the beaker. the mixture was stirred with a glass rod and allowed to stand for 30 minutes. a ph meter was then inserted into the mixture when it was partially settled and the ph of the soil was then measured. the electrical conductivity of the soil was measured using a conductivity meter. the conductivity of the soil was determined using a ratio of 1:5 of soil and distilled water solution. the model of the conductivity meter used was wtw model [8]. 2.3. percentage organic carbon and organic matter the method of walkey and black [19] was used in determining the amount of organic carbon in the soil. about 2 g of the already prepared soil sample was weighed into a conical flask, then a standard solution of 10 ml k2cr2o7 was added to the sieved soil sample and then 20 ml of concentrated h2so4 was added so that chloride ions will not interfere in the process. the solution was then allowed to settle down for a time interval of 30 minutes, while stirring was done occasionally. dilution of the content in the conical flask was performed by the addition of 10 ml of distilled water. a ferroin indicator was used as an indicator to determine the excess k2cr2o7 which was titrated with standard 1.0 n ferrous sulphate solution. the percentage organic carbon in the sample was then calculated using the formula % organic carbon = ( ) ( ) where, mc = normality of solution x volume (ml) of solution used f = correlation factor = 1.33 asian review of environmental and earth sciences, 2021, 8(1): 62-67 64 © 2021 by the authors; licensee asian online journal publishing group the percentage organic matter was then calculated using the expression % organic matter = % organic carbon x 1.724 2.4. particle size determination soil particle size determination of the samples was performed in accordance with the method of bouyoucos [20]. a 50 ml solution of cagon was used in soaking 50 g of the sieved soil sample overnight. the prepared mixture was put into a measuring cylinder of 1000 ml volume. the mixture was then added to the 1000 ml mark then shaken and allowed to settle for 40 seconds before the hydrometer was dipped into the soil for the sandy content determination, the clay and silt contents were determined after an interval of 3 hours (when the mixture have settled down) following the same method. the temperature at 40 seconds and 3 hours intervals were recorded simultaneously with the hydrometer readings and designated t1 and t2, h1 and h2 respectively. the particle size analysis calculations were then made thus, % sand = 100 – [h1 + 0.2 (t1 – 68) – 2.0]2 % clay = [h2 + 0.2 (t2 – 68) – 2.0]2 % silt = 100 – (% sand + % clay) 3. results and discussion the results for the physicochemical properties of the soil within the vicinities of the steel-welding and fabrication workshops during the months of investigation are shown in tables 1-4, while the average values of the physicochemical parameters within the months are shown in table 5. 3.1. soil ph the results obtained from the sample locations showed that the values of ph ranged from 6.7-6.9 with a mean value of 6.8±0.08, 6.8-7.0 with a mean value of 6.9±0.11 and 7.0-7.1 with a mean value of 7.1±0.05 for egbelu, elioparanwo and st. john soils respectively. the results obtained were within the limit approved by world health organization (who) [21] of 6.5-8.5. the values of ph in this study were lower than that of elemile, et al. [22] that ranged between 7.19±0.25-7.83±0.02 in a soil impacted by the activities of abattoir, but was higher than that obtained by osakwe and okolie [23] that had a mean ph value of 5.15±0.48 and was also slightly above or below the range 6.22-7.52 in a study conducted by ediene and iren [24] on the impact of abattoir effluents on the ph of the soil. soil ph affects the metal dynamics of the soil due to its ability to control the adsorption and precipitation which are useful in the retention of metals in the soils. a decrease in ph makes the metals to be more soluble and are more in the cationic forms are can be easily absorbed by plants [25]. soil ph in the range 6-8.5 shows a normal soil [2]. the ph results recorded in this work therefore revealed that the steel-welding and fabrication workshops has not impacted negatively on the soil ph within the vicinity of the studied area. this might be due to the proximity of the workshops to the drainage system in the areas investigated and possibly the falloffs were easily washed to the drain giving rise to the results obtained. 3.2. electrical conductivity the values obtained from the results in tables showed that the electrical conductivity of the soils in the different locations ranged from 64-66 µs/cm with a mean value of 65.25±0.83 µs/cm, 72-74 µs/cm with a mean value of 73±0.71 µs/cm and 75-77 µs/cm with a mean value of 76±0.71µs/cm for egbelu, elioparanwo and st. john respectively. the values of electrical conductivity obtained in this work was far lower than that reported by edori and iyama [7] which was between 269.22-406.86 µs/cm in soils from selected abattoirs in port harcourt and far higher than that recorded by fomenky, et al. [8] which was between 0.043-0.148 µs/cm in a research conducted in soils around some rivers in cameroon. high values of electrical conductivity indicate high presence of salts that are soluble in the soil [26]. soil electrical conductivity show the presence of ions and ionizable inorganic materials in the soil [27]. electrical conductivity is an important soil property useful in checking the soil quality and also a useful check on the health status of soils [28]. 3.3. percentage total organic carbon and soil organic matter the results from tables showed that percentage total organic carbon from the study locations were in the range 0.394-0.397% with a mean value of 0.396±0.001% for egbelu, 0.523-0.526% with a mean value of 0.525±0.001% for elioparanwo and 0.446-0.449% with a mean value of 0.448±0.001%, for st. john soils. the values shown in the results for percentage soil organic matter were in the range 0.679-0.684% with a mean value of 0.682±0.002% for egbelu, 0.902-0.907% with a mean value of 0.904±0.002% for elioparanwo and 0.769-0.774% with a mean value of 0.772±0.002% for st. john soils. the values of percentage organic carbon recorded in this work was lower than that obtained by olayinka, et al. [29] which had an average value of 4.80±2.65% at a depth of 0-5cm and 2.40±0.29% at a depth of 10-15cm and also lower than that obtained by edori and iyama [7] in soils used for abattoir within port harcourt metropolis with value range of 12.69-16.97%. the values obtained by abdulhamid, et al. [25] which fell within the range of 0.95-2.25% was also higher than the recorded values in this work. the values of percentage organic carbon recorded in this work was far lower than that approved for organic soil of 12-18%. the percentage organic matter recorded in this work was lower than the range 1.63-3.87% recorded by abdulhamid, et al. [25] and that obtained by fomenky, et al. [8] with a range of 0.81-3.53% and also that obtained by martínez-mera, et al. [5] of 2.906.45% in an irrigation district in colombia. total organic carbon and total organic matter are useful tools and indices in understanding the level of organic materials in the soil and also show the fertility, moisture available and level of soil development for agricultural purposes [7]. soil organic matter is a sink and major source of soil organic carbon and the organic content of carbon vary from place to place [25, 30]. soil organic matter increases the ability of the soil to hold more water, affects the soil structure, the rate of air and water infiltration biological activities and also the contribution of nutrients. soil organic matter also help in indication of cation exchange capacity of soil [31]. the low content of asian review of environmental and earth sciences, 2021, 8(1): 62-67 65 © 2021 by the authors; licensee asian online journal publishing group organic carbon and organic matter from the studied soil might have come from the fact that the steel-welding and fabrication workshops were situated at elevated positions and were close to the drainage system hence the soils of the workshops are always swept away by rain or wind into the drainage. due to the low content of organic carbon and organic matter in the soils of the studied locations, the soil might not be good enough for agricultural production such as crop planting. 3.4. particle size distribution and analysis the results indicated in the tables showed that particle size distribution and analysis from the locations were in the range of 74-76% with a mean value of 75±0.71%, 77-79% with a mean value of 78±0.71% and 78-80% with a mean value of 79±0.71% for sand in egbelu, elioparanwo and st. john soils respectively, 10-12% with a mean value of 11±0.71%, 8-10% with a mean value of 9.25±0.83% and 10-11% with a mean value of 10.5±0.5% for clay in egbelu, elioparanwo and st. john soils respectively and 13-15% with a mean value of 14±0.71%, 11-14% with a mean value of 12.75±1.09% and 10-11% with a mean value of 10. 75±0.5% for silt in egbelu, elioparanwo and st. john soils respectively. the observed values of the percentage of sand particles in this work was within the range or higher than that observed by fomenky, et al. [8] which was between 44-76%, and higher than that observed in the work of olayinka, et al. [29] that ranged between 48.45±3.31-70.35±15.82% in the soils around abattoirs, filling stations, mechanic workshops and hospital incinerators sites within a depth range of 0-5cm, 5-10cm and 10-15cm, and was also higher than that recorded by edori and iyama [7] with a mean value range of 53.00±0.81-56.50±1.73% in selected abattoirs in port harcourt. the percentage of clay obtained in this work were lower than that observed in the work of edori and iyama [7] with an average value of 26.75±1.5-28.75±5±0.96%, but higher than that obtained in the work of olayinka, et al. [29] that had a low range of 2.90±3.48-9.38±1.21% and that of fomenky, et al. [8] that ranged from 2-7%. the observed value of percentage silt in this work were lower than that recorded by fomenky, et al. [8] which ranged from 20-29% and that of edori and iyama [7] that ranged from 14.75±1.619. 75±1.71% and also that of olayinka, et al. [29] that was between 20.08±10.66-48.43±4.04%. the percentages of the different particle sizes of the soils considered in the studied locations, sand, clay and silt is known as textural class. the soil texture measures the physical characteristics of the soil. such physical characteristics include water retention capacity, permeability, soil toughness or ease of tillage, soil plasticity and soil productivity [32]. the sandy nature of the soil observed in this work will allow easy percolation of water and therefore has the high tendency to promote the contamination of the groundwater. clay particles which helps in preventing water percolation due to its slimy and non-porous nature and closed pore spaces had a low percentage in this work hence the soil under investigation may not have the potential to hold much water. this observation is in agreement with that observed by brady [33]. water percolation cannot be easily prevented [34] because clay acts naturally to filter water and other contaminants [7]. the clay particles have exchange surfaces substantial enough to absorb and stabilize soil organic matter and available heavy metals [35] and to make them useful to plants. the low level of silt recorded in this work stem from the fact that the top soil was always swept away and there is not enough time given in the workshops for decay and deposition of materials that will form silty particles over the years. table-1. physicochemical properties of steel-welding and fabrication soils in the month of may. sample location physicochemical parameters ph electrical conductivity (µs/cm) % soil organic carbon % soil organic matter particle size analysis % sand % clay % silt egbelu 6.7 65 0.396 0.683 75 10 15 elioparanwo 6.8 73 0.523 0.902 78 8 14 st. john 7.0 76 0.446 0.769 79 11 10 table-2. physicochemical properties of steel-welding and fabrication soils in the month of july. sample location physicochemical parameters ph electrical conductivity (µs/cm) % soil organic carbon % soil organic matter particle size analysis % sand % clay % silt egbelu 6.9 66 0.394 0.679 76 11 13 elioparanwo 6.7 72 0.525 0.905 77 10 13 st. john 7.1 75 0.447 0.771 80 10 11 table-3. physicochemical properties of steel-welding and fabrication soils in the month of september. sample location physicochemical parameters ph electrical conductivity (µs/cm) % soil organic carbon % soil organic matter particle size analysis % sand % clay % silt egbelu 6.8 64 0.397 0.684 74 12 14 elioparanwo 6.9 74 0.526 0.907 79 10 11 st. john 7.0 77 0.449 0.774 78 11 11 table-4. physicochemical properties of steel-welding and fabrication soils in the month of november. sample location physicochemical parameters ph electrical conductivity (µs/cm) % soil organic carbon % soil organic matter particle size analysis % sand % clay % silt egbelu 6.7 66 0.395 0.681 75 11 14 elioparanwo 7.0 73 0.524 0.903 78 9 13 st. john 7.1 76 0.448 0. 772 79 10 11 asian review of environmental and earth sciences, 2021, 8(1): 62-67 66 © 2021 by the authors; licensee asian online journal publishing group table-5. mean value of physicochemical properties of steel-welding and fabrication soils in the months under investigation. sample location physicochemical parameters ph electrical conductivity (µs/cm) % soil organic carbon % soil organic matter particle size analysis % sand % clay % silt egbelu 6.8±0.08 65.25±0.83 0.396±0.001 0.682±0.002 75±0.71 11±0.71 14±0.71 elioparanwo 6.9±0.11 73±0.71 0.525±0.001 0.904±0.002 78±0.71 9.25±0.83 12.75±1.09 st. john 7.1±0.05 76±0.71 0.448±0.001 0.772±0.002 79±0.71 10.50±0.50 10.75±0.43 4. conclusion the impact of steel-welding and fabrication was assessed to understand how such activity affected the soil quality within the environment where it is sited. the study revealed that the physicochemical characteristics of the soil within the steel-welding and fabrication workshop were not altogether higher than those of the recommended values. further study should be carried out on the physicochemical parameters in steel-welding and fabrication workshops to further ascertain this observation, since there is the possibility that the workshops used in the study became operational few years ago and might not have impacted on the soil. although the physicochemical parameters in the soils of the studied area have not reached a concentration that will affect the ecosystem, effort and proper control measures should be kept in place at checkmating the welding and fabricating of steel materials to avert the possibility of its effect on the soil quality and structure in the near future. references [1] s. de alba, d. torri, l. borselli, and m. lindstrom, "soil degradation and modification of agricultural landscapes by mechanical erosion (tillage erosion)," soiling, vol. 10, pp. 93-101, 2003. [2] s. kekane, r. chavan, d. shinde, c. patil, and s. sagar, "a review on physicochemical properties of soil," international journal of chemical studies, vol. 3, pp. 29-32, 2015. [3] y. garcia, w. ramirez, and s. sanchez, "soil quality indicators: a new way of evaluating this resource," forage pastures, vol. 35, pp. 125-138, 2017. [4] e. a. martinez-mera, a. c. torregroza-espinosa, a. valencia-garcia, and l. rojas-geronimo, "distribution of nitrogen fixing bacteria isolates and its relationship to the physicochemical characteristics of southern agricultural soils of the atiantico department, colombia," soil environment, vol. 36, pp. 174-181, 2017.available at: https://doi.org/10.25252/se/17/51202. [5] a. e. martínez-mera, t.-e. a. carolina, c.-b. t. josé, m.-n. j. luis, and g.-m. l. carlos, "evaluation of contaminants in agricultural soils in an irrigation district in colombia," heliyon, vol. 5, p. e02217, 2019.available at: https://doi.org/10.1016/j.heliyon.2019.e02217. [6] chesworth, encyclopedia of soil science. dordrecht, nertherland: springer, 2008. [7] o. edori and w. iyama, "assessment of physicochemical parameters of soils from selected abattoirs in port harcourt, rivers state, nigeria," journal of environmental analytical chemistry, vol. 4, pp. 1-5, 2017.available at: https://doi.org/10.4172/23802391.1000194. [8] n. n. fomenky, a. s. tening, g. b. chuyong, k. mbene, g. a. asongwe, and v. b. che, "selected physicochemical properties and quality of soils around some rivers of cameroon," journal of soil science and environmental management, vol. 9, pp. 68-80, 2018.available at: https://doi.org/10.5897/jssem2018.0672. [9] v. e. manga, g. n. neba, and c. suh, "environmental geochemistry of mine tailings soils in the artisanal gold mining district of bétaré-oya, cameroon," environmental pollution, vol. 6, pp. 52-61, 2017.available at: https://doi.org/10.5539/ep.v6n1p52. [10] m. seifi, r. alimardani, and a. sharifi, "how can soil electrical conductivity measurements control soil pollution?," research journal of environmental and earth sciences, vol. 2, pp. 235-238, 2010. [11] n. b. sutton, f. maphosa, j. a. morillo, w. abu al-soud, a. a. langenhoff, t. grotenhuis, h. h. rijnaarts, and h. smidt, "impact of long-term diesel contamination on soil microbial community structure," applied and environmental microbiology, vol. 79, pp. 619630, 2013.available at: https://doi.org/10.1128/aem.02747-12. [12] a. k. nazir, "effect of motor oil contamination on geotechnical properties of over consolidated clay," alexandria engineering journal, vol. 50, pp. 331-335, 2011.available at: https://doi.org/10.1016/j.aej.2011.05.002. [13] i. akinwumi, d. diwa, and n. obianigwe, "effects of crude oil contamination on the index properties, strength and permeability of lateritic clay," international journal of applied sciences and engineering research, vol. 3, pp. 816-824, 2014. [14] c. devatha, a. v. vishal, and j. p. c. rao, "investigation of physical and chemical characteristics on soil due to crude oil contamination and its remediation," applied water science, vol. 9, pp. 1-10, 2019.available at: https://doi.org/10.1007/s13201-0190970-4. [15] y. hu, s. wang, and s. yan, "research advances on the factors influencing the activity and community structure of soil microorganism," chinese journal of soil science, vol. 37, pp. 170-176, 2006. [16] e. i. akubugwo, g. c. ogbuji, c. g. chinyere, and e. a. ugbogu, "physicochemical properties and enzymes activity studies in a refined oil contaminated soil in isiukwuato, abia state, nigeria," biochemistry, vol. 21, pp. 79-84, 2009.available at: https://doi.org/10.4314/biokem.v21i2.56474. [17] x. wang, j. feng, and j. zhao, "effects of crude oil residuals on soil chemical properties in oil sites, momoge wetland, china," environmental monitoring and assessment, vol. 161, pp. 271-280, 2010.available at: https://doi.org/10.1007/s10661-008-0744-1. [18] o. bamgbose, o. odukoya, and t. arowolo, "earthworms as bio-indicators of metal pollution in dump sites of abeokuta city, nigeria," tropical biology journal, vol. 48, pp. 229-234, 2000. [19] a. walkey and a. i. black, "an examination of the degtjareff method for determining soil organic matter, and a proposed modification of the chronic acid titration method," soil science, vol. 37, pp. 29-38, 1934.available at: https://doi.org/10.1097/00010694-193401000-00003. [20] g. j. bouyoucos, "hydrometer method improved for making particle size analyses of soils 1," agronomy journal, vol. 54, pp. 464465, 1962.available at: https://doi.org/10.2134/agronj1962.00021962005400050028x. [21] world health organization (who), "guidelines for drinking water quality." vol. 1, 3rd ed geneva, switzerland: world health organization, 2004. [22] o. elemile, o. raphael, d. omole, o. oluwatuyi, e. ajayi, o. umukoro, and m. elemile, "assessment of the impact of abattoir activities on the physicochemical properties of soils within a residential area of omu-aran, nigeria," in iop conference series: materials science and engineering, 2019, p. 012083. [23] s. a. osakwe and l. p. okolie, "physicochemical characteristics and heavy metals contents in soils and cassava plants from farmlands along a major highway in delta state, nigeria," journal of applied sciences and environmental management, vol. 19, pp. 695-704, 2015.available at: https://doi.org/10.4314/jasem.v19i4.18. [24] v. ediene and o. iren, "impact of abattoir effluents on the ph, organic matter, heavy metal levels and microbial composition of surrounding soils in calabar municipality," asian journal of environment & ecology, vol. 2, pp. 1-10, 2017.available at: https://doi.org/10.9734/ajee/2017/33341. [25] z. abdulhamid, e. agbaji, c. gimba, and a. agbaji, "physicochemical parameters and heavy metals content of soi l samples from farms in minna," international letters of chemistry, physics and astronomy, vol. 58, pp. 154-163, 2015.available at: https://doi.org/10.18052/www.scipress.com/ilcpa.58.154. http://www.scipress.com/ilcpa.58.154 asian review of environmental and earth sciences, 2021, 8(1): 62-67 67 © 2021 by the authors; licensee asian online journal publishing group [26] m. e. arias, j. a. gonzález-pérez, f. j. gonzález-vila, and a. s. ball, "soil health: a new challenge for microbiologists and chemists," international microbiology, vol. 8, pp. 13-21, 2005. [27] m. a. fullen, w. fearnehough, d. mitchell, and i. trueman, "desert reclamation using yellow river irrigation water in ningxia, china," soil use and management, vol. 11, pp. 77-83, 1995.available at: https://doi.org/10.1111/j.1475-2743.1995.tb00500.x. [28] k. s. tale and s. ingole, "a review on role of physico-chemical properties in soil quality," chemical science review and letters, vol. 4, pp. 57-66, 2015. [29] o. o. olayinka, o. o. akande, k. bamgbose, and m. t. adetunji, "physicochemical characteristics and heavy metal levels in soil samples obtained from selected anthropogenic sites in abeokuta, nigeria," journal of applied science and environmental management, vol. 21, pp. 883-891, 2017.available at: https://doi.org/10.4314/jasem.v21i5.14. [30] c. perie and r. ouimet, "organic carbon, organic matter and bulk density relationships in boreal forest soils," canadian journal of soil science, vol. 88, pp. 315-325, 2008.available at: https://doi.org/10.4141/cjss06008. [31] w. r. horworth, "the importance of soil organic matter in the fertility of organic production systems," presented at the western nutrient management conference, salt lake city, ut, 2005. [32] b. m. amos-tautua, a. o. onigbinde, and d. ere, "assessment of some heavy metals and physicochemical properties in surface soils of municipal open waste dumpsite in yenagoa, nigeria," african journal of environmental science and technology, vol. 8, pp. 4147, 2014.available at: https://doi.org/10.5897/ajest2013.1621. [33] n. c. brady, the nature and properties of soils, 11th ed. new york: mcmillan, 1996. [34] p. m. ahn, tropical soil and fertilizer use. uk: longman scientific technical, 1993. [35] s. s. dara, a textbook of environmental chemistry and pollution control, 7th ed. new delhi: s. chand and company limited, 2000. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 50 © 2023 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 10, no. 1, 50-61, 2023 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v10i1.5251 © 2023 by the authors; licensee asian online journal publishing group quantitative morphometric analysis of a river basin using gis techniques: case study of miljacka river, bosnia and herzegovina emina ajanovic1 aida korjenic2 ( corresponding author) 1,2university of sarajevo, faculty of science, department of geography, sarajevo, bosnia and herzegovina. 1email: emina.ajanovic2@gmail.com 2email: aida.k@pmf.unsa.ba abstract this paper concerns the analysis of the morphometric characteristics of the miljacka river basin using the digital elevation model of the terrain in the geographical information system. a quantitative geomorphological analysis of general characteristics was performed, whereby the analysis was supplemented with specific parameters of the drainage system, which are of linear, areal and relief characteristics. standard mathematical formulas and software tools for surface and hydrology in the gis software environment were used to estimate the mentioned parameters, using arcmap 10.4. by working in the arc map program, a database system was created, with the use of a grid system, which offers the possibility of overlaying geospatial data, extracting certain parameters and their analysis and synthesis. the analyzed parameters are indicators of the shape and recent processes in the relief. they represent a supplement in the inventory and typification of relief forms, which, thanks to gis software, have a geographic reference, which facilitates their correlation. the importance of the conducted analysis is reflected in the fact that the obtained data have a numerical value, are verifiable and can be applied multiple times in practice for the purposes of determining erosive processes, protecting and improving space and the living environment, solving water management problems, planning economic activities and drafting spatial plans. keywords: geomorphology, digital elevation model, gis, hydrology, miljacka river basin, planning. citation | ajanovic, e., & korjenic, a. (2023). quantitative morphometric analysis of a river basin using gis techniques: case study of miljacka river, bosnia and herzegovina. asian review of environmental and earth sciences, 10(1), 50–61. 10.20448/arees.v10i1.5251 history: received: 6 october 2023 revised: 4 december 2023 accepted: 14 december 2023 published: 21 december 2023 licensed: this work is licensed under a creative commons attribution 4.0 license publisher:asian online journal publishing group funding: this study received no specific financial support. institutional review board statement: not applicable. transparency: the authors state that the manuscript is honest, truthful, and transparent, that no key aspects of the investigation have been om it ted, and that any differences from the study as planned have been clarified. this study followed all writing ethics. competing interests: the authors declare that they have no competing interests. authors’ contributions: both authors contributed equally to the concept ion and design of the study. both authors have read and agreed to the p ublished version of the manuscript. contents 1. introduction ................................................................................................................................................................................................... 51 2. study area ...................................................................................................................................................................................................... 51 3. methods ........................................................................................................................................................................................................... 53 4. results and discussions ............................................................................................................................................................................. 55 5. conclusions..................................................................................................................................................................................................... 60 references ........................................................................................................................................................................................................... 60 mailto:emina.ajanovic2@gmail.com mailto:aida.k@pmf.unsa.ba https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v10i1.5251 https://orcid.org/0009-0005-2196-863x https://orcid.org/0000-0003-0985-7943 asian review of environmental and earth sciences, 2023, 10(1): 50-61 51 © 2023 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the use of gis in this work made it possible to obtain specific data on the various geo morphological and hydrological characteristics of the watershed. in the same way, other watersheds in bosnia and herzegovina can be analyzed, which will contribute to better spatial planning, arrangement and use of space. 1. introduction in the last few decades, a significant focus in the field of geomorphology was directed to the development of quantitative methods important for the analysis of the genesis, evolution and behavior of drainage systems [1]. the branch of geomorphology, based on an analytical-cartographic approach and quantitative characteristics of the earth, is geomorphometry. it is an interdisciplinary field whose scientific and methodological basis is in mathematics, natural sciences and informatics [2]. morphometry as such includes methods that are basically geomorphological, based on the principles of computer analysis of the geographical information system (gis). gis has proven advantages in the areas of visualization of spatial data and manipulation of a large number of data, which is basically a characteristic of morphometric analyses. in addition to the obvious advantage in the area of collecting and manipulating a significant amount of data, gis is an effective tool for preparing data for modeling [3]. considering the above, this tool encompasses a significant number of scientific disciplines, and in addition to being successfully used in scientific research, it is an indispensable part of work processes in the field of resource management, property management, development and spatial planning, cartography and infrastructure planning [1]. an indispensable part of modern geomorphometric analysis, which uses the wide possibilities of the geographic information system, is the digital elevation model of the terrain [2]. a digital elevation model represents a special type of geodata, in the form of a digital statistical terrain model with a series of known three coordinates [4, 5]. it is based on the collection of height data, by sampling points with a certain accuracy and interpolation into software programs, continuous quantitative data on the terrain is obtained in the form of raster data [4, 6, 7]. in the earth sciences, gis methods are improving more and more rapidly, new machine learning algorithms are being developed, and automation in geospatial analysis is improving the precision and quality of modeling and geo visualization[8]. the last decade has been characterized by a large number of geoportals from which medium-resolution dem data can be downloaded, which has facilitated and improved research in this area. morphometric characteristics of drainage systems show a significant level of dependence on natural factors. the characteristics of the surface conditioned by the geological structure and climatic influences are directly reflected in the creation and parameters of the river network and basin [9]. although it is primarily a hydrological unit, the river basin also represents a natural entity, and is therefore a subject for physical, economic and social planning and development [10, 11]. given the aforementioned high level of interdependence between natural factors and the river basin, changes in any component of the watershed can change the entire environment of the watershed [12]. gis data can also contain data on the risk of torrential floods, which helps to reduce potential risks and their consequences in all spheres of life kovačević-majkić, et al. [13]. ivanova ivanova, et al. [14] states that morpho-hydrographic analyses, which are based on hydrographic and geomorphological methods and gis, have their practical application especially in the sustainable use and management of natural resources. the results obtained from the quantitative geomorphological analysis carried out in this paper concerning the miljacka river basin are of great importance in determining the intensity of erosive processes in the recent period, protecting and improving space and the environment. morphometric parameters are presented tabularly, graphically and on thematic geomorphological maps. 2. study area miljacka represents the right tributary of the bosna river, one of the most important hydrographic streams of bosnia and herzegovina. it mostly flows through sarajevo, the capital of the state (figure 1). miljacka is formed by the confluence of the paljanska and the mokranjska miljacka in the area of the han bulozi settlement, and flows into the bosna river in the rajlovac settlement. using hydrological tools for extracting the river network in the gis software environment, the total length of the miljacka river was determined to be 20.02 km, or, with its larger component, a length of 40.43 km. the catchment area of 378.51 km2 drains the mountainous terrain of the northern part of ravna planina and trebević, the southwestern slopes of romanija, the southern parts of bukovik and crepoljski uplands. the lowest point in the watershed includes the area of the river mouth in bosna and is 478 m, while the highest point is on the slope of jahorina, at an altitude of 1665 m.a.s.l. this area is characterized by the heterogeneity of the geological structure. relations between the hydrological collectors (limestones and dolomites) and isolators (werfen deposits) caused the creation of springs. according to figure 2, rocks of intergranular porosity are represented by alluvial deposits of miljacka. fissure porosity is found in ladinic deposits, while cavernous-fissure porosity is a feature of anisic limestone. triassic carbonates are the most important aquifer of potable groundwater in the miljacka river basin. predominantly impermeable complexes are clastics of the lower triassic and deposits of "orlovački" conglomerates of the upper miocene, while practically impermeable rocks are miocene sediments of the “koševska” series. according to the values of the basic climatic parameters, the miljacka catchment area primarily belongs to the cfb climate, while hypsometrically, the entire basin is under the influence of the cfc and dfb climates [15]. c climate class is determined with regard to the thermal regime recorded at meteorological stations. the mean temperature of the hottest month is higher than 10 °c, and the mean temperature of the coldest month is above -3 °c drešković and mirić [16]. drešković and mirić [16] state that areas of the cf climate type in the average annual pluviometric regime do not have a pronounced dry period, which can be noticed based on the annual flow precipitation at all three meteorological stations. the annual amount of precipitation in the basin area is determined by the regional position of the area in relation to the mediterranean and continental influence, as well as the relief characteristics of the wider area. the amount of precipitation is indirectly related to the annual course of temperatures, air humidity and cloudiness, as the main factors of condensation and sublimation of water vapor asian review of environmental and earth sciences, 2023, 10(1): 50-61 52 © 2023 by the authors; licensee asian online journal publishing group and its excretion in the form of precipitation. the sum of annual precipitation ranges from 947.4 on meteorological station bjelave to 968.8 on meteorological station pale. figure 1. the location of the miljacka watershed on the map of bosnia and herzegovina. figure 2. hydrogeological map of the miljacka catchment area. by comparing the analyzed meteorological indicators with those in the recent period, recorded at the bjelave meteorological station, certain changes can be observed. average annual temperature for the period 2010 -2020 was 11.1°c, which is an increase of 1.7°c compared to the previously analyzed time period. average monthly temperatures are increasing, and the maximum temperature was recorded in august. annual amounts of precipitation have been decreasing in the recent period, which indicates a slight increa se in the influence of the mediterranean pluviometric regime. figure 3. shows that the largest amount of precipitation was recorded in the period of climatological spring, with a maximum during the month of may. the hydrographic characteristics of the upper part of the basin are conditioned by the local geological-tectonic situation and relief energy, and in the hydrological sense, contacts of water-permeable carbonate deposits with water-bearing verfen deposits are significant. consequently, the upper part of the basin is abundant with water. the dominance of hydrological collectors in the central part of the basin caused the rare appearance of weaker sources and surface flows (figure 2), which are also characterized by large drops in the river beds, due to the topographical situation. the hydrographic characteristics of the lower part of the basin are determined by the presence of oligo-miocene sediments, alluvial sediments and anthropogenic factors. in this segment, a significant part of the river miljacka and its larger tributaries in the sarajevo region, for the purposes of expanding the urban system, was subjected to hydromelioration and construction works of the underground sewerage network of the city of sarajevo. at the water measuring station the maximum water level values during the year were registered in the spring period, due to snow retention. the highest flows are positioned in the spring season (march june), winter (december february) and autumn (october november), while the lowest flows are a characteristic of the summer season (july september). asian review of environmental and earth sciences, 2023, 10(1): 50-61 53 © 2023 by the authors; licensee asian online journal publishing group figure 3. climate diagram for meteorological station sarajevo in the period 2010-2020. source: federal hydrometeorological institute [17]. on the miljacka river, there are longer regulated sections and embankments in order to protect against floods. it mainly refers to the narrower city area, and in some segments, facilities were built with the aim of protecting industrial zones and agricultural areas. 3. methods one of the most important tasks of geomorphology is the study of geomorphological processes and forms with many different aspects, which are also the object of study of auxiliary geomorphological disciplines. one of them is the morphometric analysis, which determines the metric values of the relief shape and measures the dimensions of the relief [18]. this paper includes a morphometric analysis of the basin's drainage system and relief characteristics of the researched area. the paper shows the possibility of automatic extraction and analysis, using the european digital elevation model eu-dem for the assessment of areal, linear and relief features of the researched area, with the help of the gis software arcmap 10.4. in order to overcome the procedure of physically extracting the morphometric characteristics of the drainage system from topographic maps. eu-dem model encompasses the area of 38 countries, 32 member of the european union and 6 cooperating countries [4, 19]. for the purposes of this paper, eu-dem v1.1 was used, which is the resulting data set, created by improving geopositioning, vertical accuracy and compliance of hydrological parameters. it is a continuous data set, divided into square areas of the size 1000x1000 km, with a resolution of 25 m, with a vertical accuracy of about 7 m (eu-demcopernicus land monitoring service1). the gis software environment offers the possibility of raster and vector analyses, available in the program package of tools for spatial analysis, within which the tools for hydrology were used. strapazan and petruț [21] concluded that „computerized hydrologic models have become an essential tool not only for a better understanding of the hydrologic cycle but also for a faster problem solving in hydrology, such as the ungauged catchments“ (p.95). hydrology tools were used for the purpose of separating the drainage network within the previously defined boundary of the catchment area (figure 4). after completing the preparatory steps of filling the empty cells and defining the runoff directions of each cell the watercourse network was extracted from the digital terrain model, using the output parameters of the flow accumulation function. this function is based on the number of cells, which, considering the slope of the terrain, are "poured" into each cell. the limit value for this raster data was defined by comparing the data with a topographic map, scale 1:25 000. the ranking of the river network was based on assigning a numerical order to the flows in the drainage network, and the procedure was performed with the help of the stream order function, according to straler's method. 1url: https://land.copernicus.eu/imagery-in-situ/eu-dem [20]. https://land.copernicus.eu/imagery-in-situ/eu-dem asian review of environmental and earth sciences, 2023, 10(1): 50-61 54 © 2023 by the authors; licensee asian online journal publishing group figure 4. the procedure of applying gis software tools in the morphometric analysis of the drainage basin. the aforementioned procedures included input indicators for the conducted morphometric analyzes of the drainage basin, of linear and surface characteristics. the analyzes were carried out with the help of operations on the attributes of geographic entities, which are presented further in this paper. relief features are an important factor and have a key meaning in the spatial planning process, where they are analyzed from four aspects: morphogenetic, morphological, morphometric and morphographic features of the terrain. for the evaluation of the validity, limitations and/or convenience of the terrain, for the settlement of the population, the construction of residential buildings, roads, lifestyle and tourist activities, morphometric and morphological characteristics are significant [22]. the morphometric analysis of the relief features was carried out using tools for surface and zonal statistics of the digital terrain model (figure 5). statistical analyzes are supplemented with the microsoft excel program, basic scientific methods and mathematical formulas. this paper includes the analysis of hypsometry, terrain slope, exposure, and special attention is paid to the methodology ofderiving parameters for vertical relief dissection. the analysis of hypsometric values is based on a digital terrain model that represents the raster structure of the data. the location of the entity is defined by a direct relationship with the grid network, where each pixel is associated with a square plot on the earth's surface, in other words each pixel has a geographic reference, and new attributes of such a data set are created based on existing attributes, for example by classification [23]. methods and algorithms integrated into the arcinfo program were used to calculate the slope of the terrain. the software program determines the values for each pixel (square area), in a way that it calculates the maximum rate of value change from that pixel to the neighboring ones that surround it radoš, et al. [2]. slopes were determined by calculating the first-order derivatives of the values within a 3x3 square [24]. the geomorphological classification of slope gradients was performed according to the dominant processes on the slopes and the corresponding relief form. consequently, the terrain slope is widely used in the analysis of slope processes (e.g. landslides), denudation, erosion and land use [22]. exposure is a function of determining the orientation of an individual cell towards the cardinal points, and in gis it is calculated using the function from the surface tool. the algorithm is based on the calculation of the exposure value of the central pixel in relation to the eight neighboring ones. the final results are subtracted from the value of 90 or 360, and the orientation of each individual cell is obtained according to the azimuths [25]. the analysis of vertical dissection implies the determination of height differences between the lowest and highest points on a unit area (m/km 2). it is an important geomorphological factor for understanding the structural and functional characteristics of the environment, in order to properly manage it. knowledge and understanding of vertical dissectionare a prerequisite for the prevention of threats of natural disasters and the rehabilitation of destructive processes [22]. according to lozić [26], the calculation of vertical dissection is based on a formula that originates from the definition of this morphometric parameter: vertical dissection = hmax – hmin/p (m/km2) (1) where: hmax maximum height in a square cell. hmin minimum height in a square cell. parea of a square cell (1 km2). the gis software environment enables the formation of square surfaces, dimensions 1x1 km, together with interpolation points where the values of hisometric parameters are defined. the calculation of the vertical relief dissection was carried out using the zonal statistics tool program, which opens the dialog box for the analysis of asian review of environmental and earth sciences, 2023, 10(1): 50-61 55 © 2023 by the authors; licensee asian online journal publishing group necessary parameters on the digital terrain model. “range” is the most important parameter during the calculation of vertical dissection, by means of which the software calculates the differences between the maximum and minimum values within each square cell separately. it is important to associate the obtained values with the accompanying attributive tables of vector data, represented by a square grid and interpolation points. this step is enabled through a unique identification code (id) code. the next step involves the point interpolations.taking into account the simplicity, input data for this procedure or the fact that in gis inverse distance interpolation is used to create a raster from point data burrough, et al. [23], for the purposes of this paper, a map of vertical relief dissection was created using the idw interpolation method. idw (inverse distance weighted) type of interpolation is a simple method in which value at the unknown point is calculated by taking the contribution of all points located in a certain radius around it with a statistical weight which is inversely proportional to the square of the distance of the point. figure 5. procedure of morphometric analysis of relief features using the tool package in gis. 4. results and discussions 4.1. general morphometric characteristics of the catchment area the general morphometric analysis included the hypsometric characteristics of the terrain of the miljacka river catchment area. during the analysis, using a digital elevation model, 13 hypsometric levels were distinguished, each with 100 m of relative height (figure 6). cartographic representation of hypsometric levels indicates a significant increase in altitude from west to east of the catchment area (figure 7). the average height of the basin is 1043 m.a.s.l. which is a consequence of the dominant representation of hypsometric levels in the categories of medium-high mountains 1000-1500 m.a.s.l., low mountains 700-1000 m.a.s.l. and high >1500 m.a.s.l. [18]. figure 6. distribution of hypsometric levels of the miljackariver basin. asian review of environmental and earth sciences, 2023, 10(1): 50-61 56 © 2023 by the authors; licensee asian online journal publishing group according to this classification, terrains that include medium-high mountain areas make up 53% of the catchment area, 32% of the catchment area is represented by the category of low mountains, 2.7% by high mountains, while the lowest parts of the terrain, up to 700 m.a.s.l., comprise 11.8% of the total area basin. the presentation of the hypsometric characteristics of the terrain allowed an insight into the clear distinction of three significant geomorphological units, with dominant processes: the mokranjska miljacka valley, the paljanska miljacka valley and the valley of miljacka from the confluence of the mokranjska and paljanska miljacka to the mouth of the bosna river. deviations in the continuous decline in the longitudinal section are the result of significant direction changes on shorter sectors in a separate watercourse network, reflected in the altitude change during the 3d analysis of the terrain. the analysis of the spatial distribution and coverage of certain categories of slope grade is important , considering their significance as indicators for the extent and intensity of morphostructural and exogeomorphological (denudation and accumulation) processes that influenced the genesis of slopes during the paleo geomorphological period, and are also an indicator of future impacts of the afore mentioned processes on their mutual relations [2]. figure 7. hypsometric map of the miljacka river basin. the represented categories of slopes are presented with regard to the dominant morphological processes, and correspond to the classification accepted by the international geographical union. table 1 summarizes selected slope categories that were used in this study. table 1. representation of terrain slope categories in the catchment area. slope (°) name of inclined surface area (km²) participation (%) 0-2° subhorizontal plains 21.24 5.61 2-5° slightly sloping grounds 45.39 11.99 5-12° inclined terrains 145.87 38.54 12-32° very inclined terrains 157.31 41.56 32-55° steep terrain 8.66 2.29 >55° very steep 0 0 slope category up to 2° of subhorizontal plains, is characteristic for the largest part of the valley extensions of mokranjska, paljanska miljacka, miljacka valley in sarajevo region, especially in the alluvial plain part (see figure 8). the second slope category in the form of slightly sloping terrain in the amount of 2-5°, represent kind of a contact zone, a gentle transition of valley extensions to steeper mountain ranges. the mentioned valleys were created on the edges, and in the eastern part of the analyzed watershed, they also include smaller valley areas of streams that denuded the slope sides in the advanced stages to the recent slope values. areas like this on the edge of the miljacka valley have been significantly anthropogenically conquered. the largest part has very inclined terrains (12-32°), with very strong slope processes, and they are represented in the eastern and central part of the asian review of environmental and earth sciences, 2023, 10(1): 50-61 57 © 2023 by the authors; licensee asian online journal publishing group basin, as a result of neotectonic movements, higher hypsometric levels of mountain areas, which are under the strong influence of fluvio-denudation processes. the exposure of slopes in geomorphological processes is very significant, given that differently exposed slopes receive different amounts of short-wave radiation, in accordance with the apparent movement of the sun, which affects the characteristics of climatic elements, and thus exo-geomorphological processes. very warm exposures are south-facing slopes [2]. figure 9 shows the distribution of exposures in the area of the miljacka basin. the highest representation is recorded by the southwest-exposed slopes (14.27%), which is in accordance with the dinaric direction of providing dominantly represented relief morphostructures. northern exposures cover considerable areas, i.e. 13.89% of the terrain. two values of northern exposures were registered, considering the fact that the gis software records the northern exposure to the west and the east from the zero azimuth, more precisely from 337.5° to 22.5° [1]. in the context of suitability, slopes with very warm and warm exposures occupy 39% of the terrain, neutral exposures account for 23%, and slopes with moderately cool and cold exposures occupy 37% of the terrain. the vertical relief dissection is a component of the overall relief dissection. from the geomorphological aspect, it is aintensity parameter of the development of geomorphological processes [27]. the analysis of the spatial representation of this parameter allows insight into endogenous processes, more precisely the tectonic activity of the area [28]. during the morphometric analysis of the vertical relief dissection, the methodology of forming a unit square grid in the amount of 1000x1000 meters was used, i.e. 1 km 2 of surface (figure 10). figure 8. slope distribution of miljacka basin. figure 9. aspect map of miljacka basin. asian review of environmental and earth sciences, 2023, 10(1): 50-61 58 © 2023 by the authors; licensee asian online journal publishing group figure 10. unit square grid for calculating the miljacka drainage basin. figure 11. vertical relief dissection map of vertical dissection in the miljacka basin. asian review of environmental and earth sciences, 2023, 10(1): 50-61 59 © 2023 by the authors; licensee asian online journal publishing group within each unit area, the lowest and highest point (height difference) is determined, the values are associated with interpolation points in the center of each square. using the method of interpolation with inverse distances, a continuous area of categories of vertical dissection was obtained, for which statistical and zonal analyzes determined total areas and participation in the spatial coverage. the least determined values (11.9 m/km2) and the largest (555.6 m/km2) of vertical dissection of the terrain indicate that there is no flattened, nor very distinct relief in the researched area. by correlating the value of the slope gradient and categories of vertical dissection, it w as determined that accumulation processes prevail in the second category of vertical dissection, while the others are characterized by denudation processes. the distribution of vertical relief dissection categories indicates clearly expressed tectonic relationships in the basin area. figure 11. shows that the western and southwestern parts are less vertically fragmented and are lowered by neotectonic movements, while the eastern, northeastern and significantly southern parts of the basin are characterized by greater vertical fragmentation due to neotectonic uplift processes. 4.2. specific morphometric characteristics of the river system quantitative morphometric analysis resulted in important parameters for the assessment and understanding of hydrological processes in the catchment area. the parameters are divided into a group of lined, areal and relief aspects of the researched area (see table 2 ) . the linear parameters include the morphometric characteristics of watercourses, and the areal, a group of watershed characteristics, based on which the derived sizes of watercourse and watershed characteristics can be calculated. the group of relief parameters completes the previous presentation of general morphometric parameters, conditioned by the hydrological processes of the analyzed basin. according to the methodology of determining the order of watercourses according to straler, the total length of watercourses of order i -vi was calculated [29]. table 2. morphometric parameters in the miljacka basin. morphometric parameters formula result unit drainage network hierarchical rank (strahler system) order stream (suf)* 1st 214.58 km 2nd 120.03 km 3rd 66.09 km 4th 20 km 5th 15.33 km 6th 20.02 km stream length (lu) lu= l1+l2+…+ln 456.1 km stream number (nu) nu= n1+n2+…+nn 775 mean stream length (lt)* 20.02 km main channel length (cl)* 16 km river flow development coefficient (c) c=lt/lmin 1.3 basin geometry basin area (a)* 378.51 km² basin perimeter (p)* the length of the outer boundary as projected onto the horizontal plane of the map. 128.02 km basin length (lb)* 35.51 km basin width (wb) wb = a/lb 10.66 km drainage density (dd) dd= lu/a 1.20 km/km2 relief characterizes minimum elevation of the basin (z)* elevation of basin mouth. 478.1 m maximum elevation of the basin (z)* 1665.6 m total basin relief (h) h = z z 1187.5 m the average elevation of the basin (ha)* 1043.4 m hypsometric integral (hi) area under the hypsometric curve 0.48 % note: *measured directly using gis software analysis using dem. source: gis analysis; according to korjenić and temimović [30]. the valleys of the lowest order are connected to the areas of the headwaters of the larger watercourses of the basin, and are mostly represented at higher hypsometric levels. smaller deviations are observed comparing the watercourses of the v and vi order, considering the specific gorge valley and the elbow bend of the mokranjska and paljanjska miljacka, on the way to their junction and the place of origin of miljacka, which flows from this area, in the tectonically predisposed and significantly aligned sector of the sarajevo area. the watercourse length in the system is first of all a reflection of the hydrogeological characteristics, i.e. the stability of the river network of the analyzed area. the obtained density value of the river network for the miljacka river basin is a consequence of the climatic and hydrogeological conditions of the terrain, and especially the hypsometric scale in the analyzed coverage, which, along with the topographic base, served as an input parameter of the limit values of the watercourse accumulation function or for defining the river network with the help of gis software tools. a very pronounced amplitude of heights in the watershed is a condition for high water flow capacity and high runoff, and thus a high potential for erosion in the watershed. the hypsographic curve is primarily important in the interpretation of the way rainwater flows towards watercourses in the hydrographic system [31]. the curve shape indicates the relief age, that is, the balance of the processes of denudation and accumulation, where the area under the curve shows the relief that should be denuded by these processes. to describe the shape of the hypsometric curve, use the hypsometric integral that quantifies the area under the curve, indicating the mature phase of the relief of the analyzed watershed (figure 12). asian review of environmental and earth sciences, 2023, 10(1): 50-61 60 © 2023 by the authors; licensee asian online journal publishing group figure 12. hypsometric curve of the miljacka river basin. 5. conclusions lately, digital elevation models have been the subject of increased usage and interest. resulting in the convenience that this type of data offers in the calculation of various morphometric parameters. the aim of this paper was to show the possibilities of calculating general and specific morphometric parameters in the miljacka river basin using software tools offered by the geographical information system, based on the analysis of raster data, such as the digital elevation model of the terrain, and vector data obtained as output parameters of previous operations. the accuracy of data obtained with such analyzes depends on the availability of raster data, their accuracy, the experience and skill of the experts who work on their preparation and application, a s well as the scale of spatial coverage for which they are applied. in order to understand the correlation of hydrological processes and the evolution of the relief, input parameters in the analyzes are important. the accuracy of the application of gis for these needs can be seen in the obtained results of measuring specific morphometric characteristics. significant result precision is possible by the automated extraction of individual surfaces of hypsometric levels, which in combination with excel analyzes enable the creation of graphical representations of the balance of the basic geomorphological processes of the area. the gis application enabled operations upondigital elevation model data of the terrain, which presented the main morphometric parameters that have a spatial reference. further application of this type of spatial data is unlimited considering the possibilities of manipulation of huge databases in geographic information systems. this fact is also recognized by the institutions responsible for spatial planning, which in the recent period use morphometric data in the assessment of terrain stability and the prevention of natural disasters. references [1] a. korjenić, a. sivac, and a. banda, "application of gis in quantitative geomorphological analysis of the una river basin (bosnia and herzegovina)," dela, vol. 48, pp. 77 – 94, 2017. https://doi.org/10.4312/dela.48.77-94 [2] d. radoš, s. lozić, and a. šiljeg, "morphometrical characteristics of the broader area of duvanjsko polje, bosnia and hercegovina," geoadria, vol. 17, no. 2, pp. 177-207, 2012. https://doi.org/10.15291/geoadria.352 [3] m. domniţa, a. i. craciun, i. haidu, and z. magyari-saska, "gis used for determination of the maximum discharge in very small basins (under 2 km2)," wseas transactions on environment and development, vol. 6, pp. 468-477, 2010. [4] f. vujović, "morphometric analysis of the gračanica river drainage basin using eu-dem data and gis techniques: (adriatic sea basin, montenegro)," in in: mirić, r., editor. proceedings of the fifth congress of geographers of bosnia and herzegovina, sarajevo, geographical society in the federation of bosnia and herzegovina , 2021, pp. 121-130. [5] c. l. miller and r. a. laflamme, the digital terrain model: theory & application . cambridge, ma: mit photogrammetry laboratory, 1958. [6] t. hengl and h. i. reuter, geomorphometry: concepts, software, applications. eds newnes, amsterdam, the netherlands: elsevier, 2008. [7] a. šiljeg, m. barada, and i. marić, digital terrain modelling. zagreb: alfa, 2018. [8] p. lemenkova, "gmt based comparative analysis and geomorphological mapping of the kermadec and tonga trenches, southwest pacific ocean," geographia technica, vol. 14, no. 4, pp. 39-48, 2019. [9] b. f. maaroof, "geomorphometric assessment of the river drainage network at al-shakak basin (iraq)," journal of the geographical institute “jovan cvijić” sasa, vol. 72, no. 1, pp. 1–13, 2022. [10] k. g. iyer and u. n. roy, watershed management and sustainable development. new delhi-2: kanishka pub, 2005. [11] y. v. r. reddy, b. m. k. reddy, y. s. ramakrishna, b. narsimlu, and l. l. somani, watershed management. udaipur-1: agrotech publishing academy, 2008. [12] p. sharma, d. deka, and r. saikia, "an analysis of changing land use pattern and its effect on umtrew basin, northeast india, " hungarian geographical bulletin, vol. 60, no. 1, pp. 67-78, 2011. [13] j. kovačević-majkić, m. urošev, d. štrbac, and a. milanović pešić, torrential floods prevention possibilities case study of the skrapež river watershed (western serbia). in book: natural disasters: prevention, risk factors and management. chapter: 5 publisher: nova science publishers inc, 2013. [14] e. ivanova ivanova, r. donchev nedkov, i. boneva ivanova, and k. lyubomirova radeva, "morpho-hydrographic analyze of black sea catchment area in bulgaria," procedia environmental sciences, vol. 14, pp. 143-153, 2012. https://doi.org/10.1016/j.proenv.2012.03.014 [15] l. žunić, "the miljacka river basic hydrological characteristics (hydrographic representation) [the miljacka river basic hydrological characteristics (hydrographic representation)], "water and me" " journal of the agency for the sava river water area sarajevo, vol. 70, no. 16, pp. 67-72, 2010. https://doi.org/10.4312/dela.48.77-94 https://doi.org/10.15291/geoadria.352 https://doi.org/10.1016/j.proenv.2012.03.014 asian review of environmental and earth sciences, 2023, 10(1): 50-61 61 © 2023 by the authors; licensee asian online journal publishing group [16] n. drešković and r. mirić, regional geography of bosnia and herzegovina i, 1st ed. sarajevo: faculty of science, university of sarajevo, 2017. [17] meteorological yearbooks, "meteorological yearbooks 2010-2020," retrieved: http://www.fhmzbih.gov.ba/latinica/klima/godisnjaci.php. [accessed 01.07.2022], 2020. [18] e. temimović, a. korjenić, and h. jahić, tectonic geomorphology, 1st ed. sarajevo: faculty of science, university of sarajevo, 2018. [19] a. bashfield and a. keim, "continent-wide dem creation for the european union," presented at the in 34th international symposium on remote sensing of environment. the geoss era: towards operational environmental monitoring. sydney, australia, 2011. [20] eu-dem, "eu-dem-copernicus land monitoring service," retrieved: https://land.copernicus.eu/imagery-in-situ/eu-dem. [accessed 27.01.2023], 2020. [21] c. strapazan and m. petruț, "application of arc hydro and hec-hms model techniques for runoff simulation in the headwater areas of covasna watershed (romania)," geographia technica, vol. 12, no. 1, pp. 95-107, 2017. https://doi.org/10.21163/gt_2017.121.10 [22] e. hrelja, "models of sustainable management of protected natural areas in bosnia and herzegovina," doctoral thesis, zagreb, faculty of science and mathematics, university of zagreb, 2017. [23] p. a. burrough, r. mcdonnell, r. a. mcdonnell, and c. d. lloyd, principles of geographical information systems. oxford: oxford university press, 2015. [24] m. pahernik, "digital analysis of the slopes of rab island," geoadria vol. 12, no. 1, pp. 3-22, 2007. https://doi.org/10.15291/geoadria.113 [25] esri, "how aspect works," retrieved: http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/howaspectworks.htm. [accessed 27. 1. 2023], 2021. [26] s. lozić, "vertical relief dissection of the land part of the republic of croatia," acta geographica croatica, vol. 30, no. 1, pp. 17-26, 1995. [27] e. temimović and a. džaferagić, "hydrogeological categorisation terrain of the sanica river basin," geographical journal of bosnia and herzegovina, vol. 8, pp. 43-56, 2017. [28] a. berila and f. isufi, "application of gis in the determination of vertical relief fragmentation: a case study on drenica river basin (kosovo)," geographia technica, vol. 16, no. 1, pp. 39-47, 2021. https://doi.org/10.21163/gt_2021.161.04 [29] f. a. fitzpatrick, "revised methods for characterizing stream habitat in the national water-quality assessment program, no. 4052," us department of the interior, us geological survey, vol. 98 1998. [30] a. korjenić and e. temimović, physicalgeographic and hydrographic characteristics of the basin and the main watercourse. in: t emimovi ć , e., ed., praktikum iz hidrografije kopna i [land hydrography practice i]. sarajevo: faculty of science, university of sarajevo, 2016. [31] m. spahić, hydrology of land. sarajevo: sarajevo publishing, 2013. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. http://www.fhmzbih.gov.ba/latinica/klima/godisnjaci.php https://land.copernicus.eu/imagery-in-situ/eu-dem https://doi.org/10.21163/gt_2017.121.10 https://doi.org/10.15291/geoadria.113 http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/how-aspectworks.htm http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/how-aspectworks.htm https://doi.org/10.21163/gt_2021.161.04 1 © 2022 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 9, no. 1, 1-8, 2022 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v9i1.3786 © 2022 by the authors; licensee asian online journal publishing group investigation of 5-year interconnections between local earth magnetic field fluctuations and acute myocardial infarction in lithuania vilmantas smalinskas1 alfonsas vainoras1,3 greta ziubryte2,3 gediminas jarusevicius3 minvydas kazys ragulskis4 rollin mccraty5 ( corresponding author) 1lithuanian university of health sciences, kaunas, lithuania. 2department of cardiology, hospital of lithuanian university of health sciences kaunas clinics, kaunas, lithuania. 3cardiology institute, lithuanian university of health sciences, kaunas, lithuania. 4kaunas university of technology, kaunas, lithuania. 5heartmath institute, california, usa. 1email: vilmantas.smalinskas@lsmuni.lt 1,3email: alfavain@gmail.com 2,3email: greta.ziubryte@gmail.com 3email: gedijaru@yahoo.com 4email: minvydas.ragulskis@ktu.lt 5email: rollin@hearthmath.org abstract the impact of the local earth magnetic field (lemf) on cardiovascular events has been studied recently. data gathered during past years encouraged us to conduct this epidemiological analysis evaluating the association between changes in lemf and hospital admissions due to ami in lithuania between august 2014 and september 2019. this study is unique due to its coverage of all lithuanian patients. the frequency of morbidity of ami was compared with the intensity of the lemf and correlation coefficient was evaluated. the lemf was measured by the global coherence monitoring network magnetometer located in lithuania. lemf was measured by pikotesla square (pt²). the lemf was analized in five frequency ranges [hz], generally called between schumann resonance, which overlap with the human brain activity waves on electroencefalogram (eeg) frequency ranges (here, they are named as sdelta (0-3.5hz), stheta (3.5-7hz), salpha (7-15hz), sbeta (15-32hz) and sgamma (32-65hz) to distinguish from the eeg bands). significant correlations between weekly admissions of ami cases and the weekly lemf strength in five frequency ranges and in total range was found. a clear negative correlation was observed between cases of ami in female group and lemf frequency ranges sdelta (0-3.5hz), stheta (3.5-7hz), salpha (7-15hz), sbeta (15-32hz) and in total range. in the second half of the year the number of ami is lower, therefore negative correlations between sdelta (0-3.5hz), stheta (3.5-7hz), salpha (7-15hz) and sbeta (15-32hz) ranges are stronger than in the first one. this is particularly noticeable in 2016 and 2018 years. keywords: acute myocardial infarction, the local earth magnetic field. citation | vilmantas smalinskas; alfonsas vainoras; greta ziubryte; gediminas jarusevicius; minvydas kazys ragulskis; rollin mccraty (2022). investigation of 5-year interconnections between local earth magnetic field fluctuations and acute myocardial infarction in lithuania. asian review of environmental and earth sciences, 9(1): 1-8. history: received: 1 december 2021 revised: 15 february 2022 accepted: 3 march 2022 published: 17 march 2022 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. mailto:vilmantas.smalinskas@lsmuni.lt mailto:alfavain@gmail.com mailto:greta.ziubryte@gmail.com mailto:gedijaru@yahoo.com mailto:minvydas.ragulskis@ktu.lt mailto:rollin@hearthmath.org https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v9i1.3786 asian review of environmental and earth sciences, 2022, 9(1): 1-8 2 © 2022 by the authors; licensee asian online journal publishing group contents 1. introduction ......................................................................................................................................................................................... 2 2. methods and procedures ................................................................................................................................................................... 3 3. results ................................................................................................................................................................................................... 4 4. discussions ........................................................................................................................................................................................... 6 5. limitations ........................................................................................................................................................................................... 6 6. conclusions .......................................................................................................................................................................................... 7 references ................................................................................................................................................................................................. 7 contribution of this paper to the literature: this is the first ever analysis presenting one-country population’s relation between incidences of acute myocardial infarction and changes in local earth magnetic field. 1. introduction the aging population inevitably faces increasing morbidity and mortality associated with ischaemic heart disease [1, 2]. despite improving therapeutic and interventional treatment methods, acute myocardial infarction (ami) remains one of the leading causes of hospital admissions and mortality worldwide, responsible for almost 10 million deaths annually [1, 2]. the growing evidence of complexity of pathogenesis of ami accounting more than existence of ordinary cardiovascular risk factors (stress, smoking, obesity, comorbidities, and unhealthy lifestyle) has been accumulated over past decades [3-8]. it was hypothesised that certain changes in the environment may adjust the occurrence of ami and other cardiovascular diseases [3-8]. ambient temperature fluctuations, humidity, and atmospheric pressure are the best-studied components, but not the only ones [3, 9-13]. increased morbidity and mortality due to cardiovascular disease in association with fluctuation of ambient temperature alone have been proved repeatedly all over the world [13-15]. in contrary to previous opinion, that increased incidences of ami were associated with higher ambient temperature [14-17], claeys, et al. [18] have found that decrease of ambient temperature by 10 degrees of celsius, increases the risk of ami by 10 percent [18]. similarly, german scientists have found that 10 degrees of celsius decrease of ambient temperature may increase the risk of ami within five days by 10 percent [15]. even more, claeys, et al. [18] assume that low ambient temperature is one of the essential factors for onset of ami for medium latitude population and is more critical than physical extension or psychological stress [18]. similarly, numerous monica study (monitoring trends and determinants in cardiovascular disease) performed between 1985 and 1994 have found that the decrease of temperature by 10 degrees of celsius is associated with 13 percent increased morbidity and mortality due to cardiovascular diseases [19]. the importance of atmospheric pressure on cardiovascular events has been highlighted in the same study [19]. scientists identified that a 10-bar decreased or increased pressure below or above the 1016 mbar is associated with increased incidences by 12 and 11 percent, respectively [19]. evidence of atmospheric pressure impact on cardiovascular disease has been proved by scientists ozheredov, et al. [4] found that increased atmospheric pressure positively correlates with arterial blood pressure [4, 11]. surprisingly, chinese scientists found that cold weather, in combination with air pollution, has the strongest effect on cardiovascular mortality [20]. in consistence, air and water pollution are considered as factors severely triggering the ami in addition to strokes, cardiac arrhythmias, and pulmonary diseases [9]. it is known that inhaled ultrasmall particles cause local inflammatory processes resulting in bronchitis and pneumonia. nevertheless, the local inflammatory chain induces systemic inflammation, which can predispose endothelial dysfunction resulting in atherosclerosis progression and vulnerable plaque ruptures manifesting as ami [9]. humans’ interactions with the environment are obvious analysing the effect of daylight on human mental and physical health in addition to the regulation of the circadian rhythms guillaume, et al. [9]; abbott, et al. [21]. wang, et al. [22] established that circadian rhythms disruption has negative effect on morbidity and mortality due to heart diseases [9, 22]. the periodicity of ami has a significant correlation to circadian rhythms [9, 23]. fornasari, et al. [24] have summarised that human haemostasis is strongly associated with circadian rhythms [24]. it was found that platelet aggregation and coagulant factors concentration are increased in morning hours in addition to decreased fibrinolytic activity and blood velocity increasement at that time of the day [24]. moreover, circadian periodicity of incidences of cardiac arrhythmias and cardiovascular events has been repeatedly proved [25, 26]. even more, solar activity and its wind-storms forming geomagnetic storms (gs) may have similar effect on human health [5]. it was found that gs may significantly increase platelet aggregation, blood coagulation, and its viscosity in addition to decreased blood flow in small and medium vessels [24]. additionally, the impact of the local earth magnetic field (lemf) on cardiovascular events has been studied during past years. it was identified that increase of lemf in certain frequencies affects differently vulnerable patients, for example, increased lemf activity in low-frequency ranges were associated with increased prevalence of acute cardiac arrhythmias [27-29]. in contrast, increased lemf activity in higher frequency ranges positively correlated with ischaemic cardiac events [27-29]. nevertheless, liboff [30] hypothesised that ion cyclotron resonance mechanism, which effect on myocardium cell has been proved under laboratory conditions, is responsible for lemf effect on humans’ health [30, 31]. moreover, lemf increase negatively influence the sensitivity of baroreceptors, which are responsible for heart rhythm variability (hrv), which is essential maintaining compensatory mechanism in healthy people and increased blood pressure variability, which may lead to hypertensive crisis in certain patients [8]. even more, it was found that for people isolated from lemf, the diastolic blood pressure reduces at least 2 mm hg, and the capillary blood flow increases at least 17 percent [32]. that let assume that lemf may increase vessel wall tone, which in severe cases, may be responsible for cardiac deaths [33]. data gathered during past years encouraged us to perform this epidemiological analysis evaluating the association between changes in lemf and hospital admissions due to ami in lithuania in period from august 2014 till september 2019. asian review of environmental and earth sciences, 2022, 9(1): 1-8 3 © 2022 by the authors; licensee asian online journal publishing group 2. methods and procedures in total, 31220 patients diagnosed with ami who were treated in all lithuanian hospitals between 1st of august 2014 and 30th of september 2019 were included into our study. patients’ morbidity and mortality data has been taken from the institute of hygiene in lithuania. the ami accidents were compared with the lemf intensity and correlation coefficient was evaluated. the lemf was measured by the global coherence monitoring network magnetometer located in radviliskis district, near baisogala town in lithuania. lemf was measured by pikotesla square (pt²) – power of local electromagnetic field in chosen frequency range. the lemf was analized in five frequency ranges [hz], generally called between schumann resonance, which overlap with the human brain activity waves on electroencefalogram (eeg) frequency ranges (here, they are named as sdelta (0-3.5hz), stheta (3.5-7hz), salpha (7-15hz), sbeta (15-32hz) and sgamma (32-65hz) to distinguish from the eeg bands). the lemf was measured in two (north/south and east/west) orientations. the east/west direction has been chosen for further analysis following the heart math institute recommendations as this lemf direction stronger influence the human health processes. seasonal and annual fluctuations of lemf intensity are shown in figure 1. data are obtained from global coherence monitoring network magnetometer located in lithuania, website https://www.heartmath.org. figure 1. average of the intensity of lemf in all months of each year. to determine the most reliable period of grouping and not to miss the delay effect of lemf, all ami cases were grouped daily, by three days, seven days and monthly. daily grouping does not include the three-day period which is determined as the optimal delay effect period, therefore grouping by three and seven days are more reliable. nevertheless, monthly grouping produces the highest significance, but it may be influenced by seasonal changes stronger than the weekly ones. to miss as less as possible impact of lemf action, it was decided to group all cases weekly, therefore further analyses will be given accordingly. seasonal fluctuations of lemf and ami are shown in figure 2. figure 2. correlation between ew orientation lemf and ami calculating in various groups of averaging. asian review of environmental and earth sciences, 2022, 9(1): 1-8 4 © 2022 by the authors; licensee asian online journal publishing group the statistical analysis was performed using the software package spss 20.0. pearson correlation coefficient for the linear correlation between two variables was calculated. the level of p < 0,05 was considered as statistically significant. 3. results of all, 18379 (58.9%) patients were male and 12841 (41.1%) were female. in average 504 patients were admitted to lithuanian hospitals due to ami monthly. significant correlations between weekly admissions of ami cases and the weekly lemf strength in five frequency ranges and in total range was found. further results will be given in certain frequency ranges. 3.1. 0-3,5 hz (sdelta) ran a negative correlation coefficient (r = 0.47, p = 0.017) between ami cases in female and lemf in 0-3.5 hz frequency range (sdelta) was found in the first half year of 2016. even stronger correlations remain in the second half of 2016 (r = 0.625, p = 0.001) and in the second half year of 2018 (r = 0.519, p = 0.006). negative correlation was observed in male group only in the second half year of 2018 (r = 0.388, p = 0.046). a stronger negative correlation between ami and lemf was observed in the total group when comparing male and female groups separately. strong negative correlation between ami in total group and this range was observed in the second half year of 2016 (r = 0.692, p = 0.000) and in the second half year of 2018 (r = 0.567, p = 0.002), they are presented in figure 3. figure 3. fluctuations of correlation coefficient between 0-3,5 hz (sdelta) lemf and ami for each gender in different periods. summarizing the effect of the sdelta frequency range and its prevailing negative correlations with ami cases, might be said that stronger lemf in 0-3.5 hz is associated with lower number of ami cases in both males and females. even more, its significance were stronger form females. therefore, this range can be accepted as having a positive effect on people with predominant ischaemic heart disease (ihd). 3.2. 3,5-7hz (stheta) range a negative correlation coefficient (r = 0.478, p = 0.013) between ami cases in female and lemf in 3.5-7 hz frequency range (stheta) was found in the first half year of 2016 and remained through the second half year of 2016 (r = 0.513, p = 0.007) and the second half year of 2018 (r = 0.481, p = 0.011). a single negative correlation in male group was observed in the second half year of 2016 (r = 0.449, p = 0.021). a stronger negative correlation between ami and lemf was observed in the whole group compared to male and female groups separately. strong negative correlation between ami in whole group and this range was observed in the second half year of 2016 (r = 0.701, p < 0.000) and in the second half year of 2018 (r = 0.505, p = 0.007). finally, correlation coefficients in 3.5-7 hz (stheta) frequency range were more significant in female group and in whole study population compared to male group, especially in the second half of 2016 and 2018 year. these results suggest that stheta frequency range as well as sdelta frequency range has a positive effect on humans’ with ihd and may be protecting against ami. 3.3. 7-15 hz (salpha) range a negative correlation coefficient (r = 0.431, p = 0.028) between ami cases in female and lemf in 7-15 hz frequency range (salpha) was found in the first half year of 2016 and remained through the second half year of 2016 (r = 0.543, p = 0.004), the second half year of 2017 (r = 0.395, p = 0.041) and the second half year of 2018 (r = 0.507, p = 0.007). a single negative correlation in male group was observed in the second half year of 2016 (r asian review of environmental and earth sciences, 2022, 9(1): 1-8 5 © 2022 by the authors; licensee asian online journal publishing group = 0.461, p = 0.018). a stronger negative correlation between ami and lemf was observed in the whole study population compared to male and female groups separately. strong negative correlation between ami in whole study population and this range was observed in the second half year of 2016 (r = 0.732, p < 0.000), second half year of 2017 (r = 0.391, p = 0.044) and the second half year of 2018 (r = 0.545, p = 0.003). summarizing, correlation coefficient in 7-15 hz (salpha) frequency range was more significant for women and in general population, especially in the second half of 2016 and 2018 year. this, as well as sdelta and stheta frequency ranges, is associated with less ami cases in lithuanian patients. 3.4. 15-32 hz (sbeta) range a negative correlation coefficient (r = 0.436, p = 0.026) between ami cases in female and lemf in 15-32 hz frequency range (sbeta) was observed in the first half year of 2016 and remained through the second half year of 2016 (r = 0.502, p = 0.009), the second half year of 2017 (r = 0.410, p = 0.033) and the second half year of 2018 (r = 0.431, p = 0.025). a single negative correlation was observed in male group in the second half year of 2016 (r = 0.481, p = 0.013). a stronger negative correlation between ami and lemf was observed in the whole study population compared to male and female groups separately. strong negative correlation between ami in total group and this range was observed in the second half year of 2016 (r = 0.715, p = 0.000), negative correlation was observed in the second half year of 2017 (r = 0.388, p = 0.046) and in the second half year of 2018 (r = 0.484, p = 0.010). in summary, correlation coefficient between ami and lemf in 15-32 hz (sbeta) frequency range was more significant in women and in general study population, especially in the second half of 2016 and 2018 year. summarizing, all these frequency ranges might be called low frequency range as all these effect on human cardiovascular system is quite similar. increased their intensity significantly correlates with less admission due to ami in all lithuanian patients. 3.5. 32-65 hz (sgamma) range slightly different trends of correlations were found in sgamma frequency range. this range is known for its positive correlation coefficients with ami cases. the first positive correlation coefficients (r = 0.410, p = 0.038) were found through the first half year of 2016 in whole study population and through the first half year of 2018 (r = 0.417, p = 0.038) in female group. a negative correlation between ami and lemf was observed only in the whole study population through the second half year of 2016 (r = 0.467, p = 0.016) which compared to general view seems rather an exception from the rule. that are shown in figure 4. figure 4. fluctuations of correlation coefficient between 32-65 hz (sgamma) lemf and ami for each gender in different periods. sgamma rage is the only range were positive correlation between ami and lemf was identified. this let assume that this frequency range is significantly associated with negative outcomes for people with predominant ihd. 3.6. comparison of range’s effects in half-years correlation between the number of ami and intensity of lemf was different not only in various frequency ranges but it was also diverse in the first and the second half year, besides they are different in every year. in order to establish a consistent pattern of lefm we calculated correlations separately in the first and in the second half of the year. results are presented in table 1. asian review of environmental and earth sciences, 2022, 9(1): 1-8 6 © 2022 by the authors; licensee asian online journal publishing group table 1. correlation coefficients between each range of lemf and ami in first and second half year. ratio of the half-year average correlation coefficient. magnetic field intensity range group hy1 hy2 hy1/hy2 0-3.5 hz total -0.22 -0.32 -0.11 -0.36 -0.06 -0.29 -0.22 -0.69** -0.28 -0.57** 1.92 male -0.29 -0.04 -0.34 -0.22 0.13 -0.28 -0.34 -0.32 -0.12 -0.39* 1.90 female -0.02 -0.47* 0.27 -0.32 -0.27 -0.23 -0.01 -0.63** -0.26 -0.52** 2.04 3.5-7 hz total -0.20 -0.35 -0.12 -0.23 -0.07 -0.32 -0.22 -0.70** -0.33 -0.51** 2.14 male -0.26 -0.06 -0.39 -0.12 0.14 -0.24 -0.32 -0.45* -0.12 -0.33 2.10 female -0.03 -0.48* 0.31 -0.24 -0.29 -0.35 -0.03 -0.51** -0.33 -0.48* 2.39 7-15 hz total -0.19 -0.26 -0.08 -0.17 -0.08 -0.26 -0.24 -0.73** -0.39* -0.55** 2.77 male -0.34 0.01 -0.30 -0.09 0.13 -0.20 -0.31 -0.46* -0.14 -0.36 2.50 female 0.06 -0.43* 0.26 -0.17 -0.29 -0.26 -0.07 -0.54** -0.40* -0.51** 3.09 15-32 hz total -0.17 -0.23 -0.11 -0.13 -0.14 -0.24 -0.22 -0.72** -0.39* -0.48* 2.63 male -0.26 0.05 -0.32 -0.08 0.06 -0.16 -0.33 -0.48* -0.12 -0.34 2.63 female 0.01 -0.44* 0.24 -0.12 -0.31 -0.27 -0.03 -0.50** -0.41* -0.43* 2.67 32-65 hz total -0.07 0.41* -0.06 0.26 -0.26 -0.11 0.22 -0.47* 0.17 0.33 0.55 male 0.25 0.25 -0.07 -0.02 -0.08 -0.05 0.26 -0.38 0.08 0.27 0.60 female -0.32 0.32 0.01 0.42* -0.35 -0.16 0.10 -0.27 0.15 0.25 0.94 year 2015 2016 2017 2018 2019 2014 2015 2016 2017 2018 note: ** correlation is significant at the 0.01 level (2-tailed). * correlation is significant at the 0.05 level (2-tailed). in our study a clear trend was observed: in the second half-year correlation coefficients in all the ranges of 0-32 hz are negative in total group, male and female groups. it means lemf of 0-32 hz has protective action for ami. this tendency is not so clear for 32-65 hz (sgamma) range. different effect of lemf on ami in the second half-year than in the first one. the ratio of the half-year average correlation coefficients shows correlation in the second-half year are 1.90-3.09 stronger than in the first one. this trend was not observed in sgamma range. 4. discussions we represent the first such numerous study focused on morbidity of ami in lithuanian population within the period of five years. in consistence with previous studies, our data showed that higher intensity lemf in low frequency ranges is associated with improved cardiovascular health [34]. in the first half of the year, as in summer, the axis of the northern hemisphere of the earth is tilted to the sun more. at that time, solar wind is stronger as the main determinant of lemf. at that time the solar wind as the main determinant of lemf is stronger. stronger solar wind leads to stronger lemf in all ranges, possibly resulting in post-exposure ami, although the action of different ranges of lemf is different. jarusevicius et al. have proved that stronger magnetic field in low frequency range is associated with lower number of weekly hospital admissions due to st elevation myocardial infarction (stemi) [28]. even more, similar results have been repeatedly shown in other study investigating the relation between weekly accidents of unstable angina and changes in the lemf intensity in five frequency ranges [29]. this is the first study with such deep focus on different frequency ranges of lemf and their associations to certain cardiovascular disease. in contrary to physics, where low frequency range is described as the range between 0 and 300 hz, in biophysics and biomedicine the low frequency range does not extend the 15 hz. nevertheless, the positive effect of ultra-low-frequency-range (0-0.02 hz) on endothelium function has been found couple years ago [35], therefore, strong negative correlations in extremely low frequency range (0-3.5hz and 3.5-7hz) in our study might be explained by this phenomena. it is interesting, that with increasing range of the lemf, the correlations get a little bit weaker. most probably, due to weaken positive effect on cardiovascular system. in europe, the electric power network works on average 50 hz frequency range [32]. it is normal, that in schumann resonance spectrum, this is the leading intensity of lemf in our country. nevertheless, exactly this range has been proved to be associated with negative cardiovascular events especially ischemic ones [28, 29]. moreover, most magnetic storms are associated with the diapason of lemf frequencies between 32 and 65 hz [35]. therefore, any geomagnetic storm may result in increased morbidity of ami. not surprisingly, the effect of magnetic storms has been repeatedly proved by various scientists globally. one of the strongest evidence has been collected in russia’s laboratories [35]. zenchenko, et al. [35] have found that in presence of magnetic storm, the capillary blood flow significantly reduces, as well as significant reduction in arterial blood flow which might be directly correlated with occurrences of ami and acute cerebrovascular ischaemias [35]. moreover, certain effects of lemf fluctuations on cell proliferation and gene expressions have been proposed in past decade lee, et al. [34]. in lee, et al. [34] study was found that under stronger magnetic field in 30-60hz frequency range, the cells’ normal cycles are inhibited and those small, but significant circle delays may result in increased cell proliferation but do not induce cell death what all together may result in neoplasms [34]. 5. limitations this study has some limitations. patients who were diagnosed with ami and were hospitalized in lithuanian hospitals were included in the study. patients who were diagnosed with ami but who were not hospitalized were not included to the study, but some patients had ami at home and did not receive medical attention, so the amount of ami may not be complete. in such cases, if a sudden death (even ami) occurs at home and the patient is not able to be hospitalized such patients were not included to the study. asian review of environmental and earth sciences, 2022, 9(1): 1-8 7 © 2022 by the authors; licensee asian online journal publishing group 6. conclusions 1. a clear negative correlation was observed between cases of ami in female group and lemf frequency ranges: sdelta, stheta, salpha and sbeta. 2. correlation coeficients between cases of ami in female group and lemf frequency ranges sdelta, stheta, salpha, sbeta are similar. correlation coeficients between cases of ami in total group and lemf frequency ranges sdelta, stheta, salpha, sbeta are similar. 3. a negative correlation between cases of ami in male group and the same lemf frequency ranges are also obvious. 4. due to the larger number of subjects, even stronger correlations is observed in the overall sample. 5. in the second half of the year the number of ami is lower, therefore negative correlations between sdelta, stheta, salpha and sbeta ranges are stronger than in the first one. this is particularly noticeable in 2016 and 2018 years. 6. interestingly, the lemf sgamma range had a statistically significant positive correlation between female morbidity due to ami in the first half year of 2016, but correlation was significantly negative in the second half of that year. it is obvious correlation between morbidity of ami and lemf. lemf in frequency ranges 0-32 hz have positive impact on human health and may act protectively. high frequency range (32-65 hz) has significantly negative effect on ihd provoking ami and may lead to worser outcomes. nomenclature: ami acute myocardial infarction. lemf local earth magnetic field. gs geomagnetic storms. hrv heart rhythm variability. eeg electroencefalogram. ihd ischemic heart disease. references [1] a. n. nowbar, m. gitto, j. p. howard, d. p. francis, and r. al-lamee, "mortality from ischemic heart disease: analysis of data from the world health organization and coronary artery disease risk factors from ncd risk factor collaboration," circulation: cardiovascular quality and outcomes, vol. 12, p. e005375, 2019.available at: https://doi.org/10.1161/circoutcomes.118.005375. [2] global health estimates, global health estimates 2016: deaths by cause, age, sex, by country and by region, 20002016. geneva, switzerland: world health organization, 2018. [3] t. zenchenko, a. skavulyak, n. khorseva, and t. breus, "characteristics of individual reactions of the cardiovascular system of healthy people to changes in meteorological factors in a wide temperature range," izvestiya, atmospheric and oceanic physics, vol. 49, pp. 784-798, 2013. [4] v. ozheredov, t. breus, y. i. gurfinkel, b. revich, and t. mitrofanova, "influence of some weather factors and geomagnetic activity on the development of severe cardiological pathologies," biophysics, vol. 55, pp. 110-119, 2010. [5] j. vencloviene, r. m. babarskiene, and d. kiznys, "a possible association between space weather conditions and the risk of acute coronary syndrome in patients with diabetes and the metabolic syndrome," international journal of biometeorology, vol. 61, pp. 159167, 2017.available at: https://doi.org/10.1007/s00484-016-1200-5. [6] s. dimitrova, i. stoilova, and k. georgieva, "solar and geomagnetic activity and acute myocardial infarction morbidity and mortality," in gundam space res, suppl of proceedings of the bulgarian academy of sciences, 2009, pp. 161–165. [7] c. katsavrias, p. preka-papadema, x. moussas, t. apostolou, a. theodoropoulou, and t. papadima, "helio-geomagnetic influence in cardiological cases," advances in space research, vol. 51, pp. 96-106, 2013. [8] j. gmitrov and a. gmitrova, "geomagnetic field effect on cardiovascular regulation," bioelectromagnetics, vol. 25, pp. 92-101, 2004. [9] c. g. guillaume, d. gubin, l. a. beaty, and k. otsuka, "some near-and far-environmental effects on human health and disease with a focus on the cardiovascular system," international journal of environmental research and public health, vol. 17, pp. 1-16, 2020.available at: https://doi.org/10.3390/ijerph17093083. [10] t. breus, y. i. gurfinkel, t. zenchenko, and v. ozheredov, "comparative analysis of different vascular tone sensitivity parameters to meteorological and geomagnetic factors," izvestiya, atmospheric and oceanic physics, vol. 46, pp. 965-972, 2010. [11] v. ozheredov, s. chibisov, m. blagonravov, n. khodorovich, e. demurov, v. goryachev, e. kharlitskaya, i. eremina, and z. meladze, "influence of geomagnetic activity and earth weather changes on heart rate and blood pressure in young and healthy population," international journal of biometeorology, vol. 61, pp. 921-929, 2017.available at: https://doi.org/10.1007/s00484-0161272-2. [12] y. gurfinkel, t. breus, t. zenchenko, and v. ozheredov, "investigation of the effect of ambient temperature and geomagnetic activity on the vascular parameters of healthy volunteers," open journal of biophysics, vol. 2, pp. 46-55, 2012. [13] y. gurfinkel, t. breus, and t. zenchenko, "investigation of the effect of ambient temperature and geomagnetic activity on the vascular parameters of healthy volunteers," open journal of biophysics, vol. 32, pp. 898-907, 2010. [14] t. messner, "environmental variables and the risk of disease," internatioal journa circumpolar health, vol. 64, pp. 523-533, 2005. [15] k. wolf, a. scheneider, and s. breitner, "air temperature and the occurrence of myocardial infarction in augsburg, germany," circulation, vol. 120, pp. 735-742, 2009. [16] c. de senarclens, a. assimacopoulos, j. altherr, c. andrey, and a. bloch, "myocardial infarction and meteorology," schweizerische medizinische wochenschrift, vol. 110, pp. 1931-1931, 1980. [17] d. miric and z. rumboldt, "the impact of meteorological factors on the onset of myocardial infarction in the coastal region of middle dalmatia," italian journal of cardiology, vol. 23, pp. 655-660, 1993. [18] m. claeys, s. coenen, and c. colpaert, "environment triggers of acute myocardial infarction: results of a nationwide multiplefatorial population study," acta cardiol, vol. 70, pp. 693-701, 2015.available at: https://doi.org/10.1080/ac.70.6.3120182. [19] s. danet, f. richard, m. l. montaye, s. beauchant, b. lemaire, c. graux, d. cottel, n. marécaux, and p. amouyel, "unhealthy effects of atmospheric temperature and pressure on the occurrence of myocardial infarction and coronary deaths: a 10-year survey: the lille-world health organization monica project (monitoring trends and determinants in cardiovascular disease)," circulation, vol. 100, pp. e1-e7, 1999.available at: https://doi.org/10.1161/01.cir.100.1.e1. [20] z. qian, h.-m. lin, w. f. stewart, l. kong, f. xu, d. zhou, z. zhu, s. liang, w. chen, and n. shah, "seasonal pattern of the acute mortality effects of air pollution," journal of the air & waste management association, vol. 60, pp. 481-488, 2010.available at: https://doi.org/10.3155/1047-3289.60.4.481. [21] s. m. abbott, r. g. malkani, and p. c. zee, "circadian disruption and human health: a bidirectional relationship," european journal of neuroscience, vol. 51, pp. 567-583, 2020.available at: https://doi.org/10.1111/ejn.14298. [22] d. wang, w. ruan, z. chen, y. peng, and w. li, "shift work and risk of cardiovascular disease morbidity and mortality: a dose– response meta-analysis of cohort studies," european journal of preventive cardiology, vol. 25, pp. 1293-1302, 2018.available at: https://doi.org/10.1177/2047487318783892. asian review of environmental and earth sciences, 2022, 9(1): 1-8 8 © 2022 by the authors; licensee asian online journal publishing group [23] s. n. willich, t. linderer, k. wegscheider, a. leizorovicz, i. alamercery, and r. schröder, "increased morning incidence of myocardial infarction in the isam study: absence with prior beta-adrenergic blockade. isam study group," circulation, vol. 80, pp. 853-858, 1989. [24] p. fornasari, l. gratton, and d. dolci, circadian rhythms of clotting, fibrinolytic activators and inhibitors,” chronobiology, il ponte. italy: milan, 1981. [25] g. cornélissen, k. tamura, b. tarquini, g. germanò, c. fersini, c. rostagno, r. zaslavskaya, o. carandente, f. carandente, and f. halberg, "differences in some circadian patterns of cardiac arrhythmia, myocardial infarctions and other adverse vascular events," chronobiologia, vol. 21, pp. 79-88, 1994. [26] g. cornélissen, t. breus, c. bingham, r. zaslavskaya, m. varshitsky, b. mirsky, m. teibloom, b. tarquini, e. bakken, and f. halberg, "international womb-to-tomb chronome initiative group: beyond circadian chronorisk: worldwide circaseptancircasemiseptan patterns of myocardial infarctions, other vascular events, and emergencies," chronobiologia, vol. 20, pp. 87-115, 1993. [27] g. ziubrytė, g. jaruševičius, j. jurjonaitė, m. landauskas, r. mccraty, and a. vainoras, "correlations between acute atrial fibrillation and local earth magnetic field strength," journal of complexity in health sciences, vol. 1, pp. 31-41, 2018. [28] g. jaruševičius, t. rugelis, r. mccraty, m. landauskas, k. berškienė, and a. vainoras, "correlation between changes in local earth’s magnetic field and cases of acute myocardial infarction," international journal of environmental research and public health, vol. 15, pp. 1-12, 2018.available at: https://doi.org/10.3390/ijerph15030399. [29] g. ziubrytė, g. jaruševičius, m. landauskas, r. mccraty, and a. vainoras, "the local earth magnetic field changes impact on weekly hospitalization due to unstable angina pectoris," journal of complexity in health sciences, vol. 1, pp. 16-25, 2018. [30] a. r. liboff, "a role for the geomagnetic field in cell regulation," electromagnetic biology and medicine, vol. 29, pp. 105-112, 2010.available at: https://doi.org/10.3109/15368378.2010.493129. [31] r. gaetani, m. ledda, l. barile, i. chimenti, f. de carlo, e. forte, v. ionta, l. giuliani, e. d'emilia, and g. frati, "differentiation of human adult cardiac stem cells exposed to extremely low-frequency electromagnetic fields," cardiovascular research, vol. 82, pp. 411-420, 2009.available at: https://doi.org/10.1093/cvr/cvp067. [32] a. karimi, f. g. moghaddam, and m. valipour, "insights in the biology of extremely low-frequency magnetic fields exposure on human health," molecular biology reports, vol. 47, pp. 5621-5633, 2020.available at: https://doi.org/10.1007/s11033-020-05563-8. [33] y. i. gurfinkel, o. y. at'kov, a. vasin, t. breus, m. sasonko, and r. y. pishchalnikov, "effect of zero magnetic field on cardiovascular system and microcirculation," life sciences in space research, vol. 8, pp. 1-7, 2016.available at: https://doi.org/10.1016/j.lssr.2015.11.001. [34] h. c. lee, m. n. hong, s. h. jung, b. c. kim, y. j. suh, y. g. ko, y. s. lee, b. y. lee, y. g. cho, and s. h. myung, "effect of extremely low frequency magnetic fields on cell proliferation and gene expression," bioelectromagnetics, vol. 36, pp. 506-516, 2015. [35] t. zenchenko, l. poskotinova, a. rekhtina, and r. zaslavskaya, "relation between microcirculation parameters and pc3 geomagnetic pulsations," biophysics, vol. 55, pp. 646-651, 2010.available at: https://doi.org/10.1134/s000635091004024x. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 8 asian review of environmental and earth sciences vol. 5, no. 1, 8-14, 2018 issn(e) 2313-8173/ issn(p) 2518-0134 doi: 10.20448/journal.506.2018.51.8.14 organic geochemistry and source rock potential of naokelekan formation in selected wells, north iraq jan i. ismael1 ( corresponding author) 1department of geological engineering, faculty of engineering, selçuk university, konya, turkey abstract in this study, organic geochemical characteristics and potential of upper oxfordian–lower kimmeridgian aged bituminous shale beds in naokelekan formation (north iraq) were investigated by using toc and pyrolysis analyses. the total organic carbon (toc) contents for the studied samples varying between from 0.46-21.33%, average 7.06% and taq taq-1 well as good hydrocarbon potential (0.85-1.66 %, with average of 1.06%), whereas jk-1 well can be rated as an very good hydrocarbon potential from 1.04-4.16 %, with average of 2.15 %. the low hydrogen index (hi = 24-605 mg hc/g toc) for bj-1 well, (hi = 147-673 mg hc/g toc) in the jk-1 well while in taq taq-1 well (hi = 9-48 mg hc/g toc) indicate that kerogen type for the vast majority of the studied samples is type ii/i for bj-1 well and type iv with few samples, type of i and ii kerogens in the taq taq-1 and jk-1 well. consequently most of the organic matter of bj-1 and jk-1 well tends to generate petrol, even though a small portion of them exhibit a tendency to generate gas. while all samples of taq taq-1 well tends to generate gas. the studied bituminous rock samples characterized by low tmax (434-602 °c) for bj-1,taq taq-1 (344429 °c) and (419-602 °c) for jk-1 well. these values show, in terms of potential of hydrocarbon generation, that the studied samples have a source rock potential of organic matter from immature to over mature. additionally, the s1 hydrocarbon type values indicate no external contribution of migrated hydrocarbons to the bituminous rocks of the studied area. keywords: soruce rock, rock eval, kerogen, naokelekan formation, north iraq. citation | jan i. ismael (2018). organic geochemistry and source rock potential of naokelekan formation in selected wells, north iraq. asian review of environmental and earth sciences, 5(1): 8-14. history: received: 13 february 2018 revised: 9 march 2018 accepted: 12 march 2018 published: 15 march 2018 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group funding: author is grateful to the selçuk university research fund for financial support (project no: 16201040), and to the north oil company in iraq for supplying well samples. competing interests: the author declares that there are no conflicts of interests regarding the publication of this paper. transparency: the author confirms that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 9 2. geological settings ............................................................................................................................................................................ 9 3. materials and methods ...................................................................................................................................................................... 9 4. results and discussions .................................................................................................................................................................. 11 5. conclusions ....................................................................................................................................................................................... 13 references .............................................................................................................................................................................................. 13 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2018.51.8.14&domain=pdf&date_stamp=2017-01-14 https://orcid.org/0000-0002-9910-3370 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2018, 5(1): 8-14 9 1. introduction rock-eval pyrolysis has been a widely used method in organic geochemistry tool for examining the oil and gas potential and maturity of different rock samples. the available information concerning the toc content, thermal maturation, and burial history are seriously required for better understanding of the existence of other hydrocarbon resources [1]. the dominant organic matter in oil shales is derived from one or more primary sources, the terrestrial plants, lacustrine algae and marine organisms. these include large lake basins of tectonic origin, small lakes, lagoons and shallow seas [2]. naokelekan formation one of the most important source rocks in iraq. the formation crops out mainly within the high folded zone of northern iraq. additionally, it is found within drilled oil wells of low folded zone in iraq such as at taq taq, jabal kand and biji oil fields. 50 core and cutting samples from naokelekan formation has been collected from bj-1, taq taq-1 and jk-1 wells and have been sent to turkish tpao research center / petroleum geochemistry department (ankara) to determine hydrocarbon potential for these samples by rock eval analysis, toc (total organic carbon) analysis and s1, s2, s3, tmax, oxygen i̇ndex, hydrogen i̇ndex results for three wells. 2. geological settings oil fields within the northern iraq coincide with part of the zagros fold belt and regionally extends within an elongated folded zone between the thrust zone in a triple junction boundary between iran and turkey with iraq. also, it extends towards the mesopotamian foredeep with khleisya uplift towards the southwestern part of northern iraq; well locations are plotted on location map of (fig.1) locating this studied area is according to buday [3]; al-sharhan and nairn [4]; sharland, et al. [5]; aqrawi, et al. [6] and the arabian peninsula basins map prepared by the us geological survey [7]. tectonically, iraq lies in the border area between the arabian part of the african (nubian-arabian) platform and the asian branches of the alpine geosyncline. the platform of iraqi territory is divided into two basic units, the stable and unstable shelf. the stable shelf is characterized by reduced thickness of sedimentary cover and by the lack of folding. the unstable shelf has thick and folded sedimentary cover [3]. fig-1. location map of iraq showing studied area of north iraq with locations of oil exploration wells stratigraphically, naokelekan formation consists of laminated bituminous limestone, alternated with bituminous shale (coal horizon) and thin bedded, highly bituminous dolomite and limestone. formation age is assigned as upper oxfordian–lower kimmeridgian according to the study of ammonites of the upper jurassic [8]. the depositional environment of the formation was interpreted as euxinic in a slow subsiding basin [3]. 3. materials and methods a total of 50 oil shale samples of the naokelekan formation were collected from 3 wells (bj-1, taq taq-1 and jk-1). these samples were crushed, pulverized and then homogenized. rock-eval pyrolysis was conducted using the rock-eval 6 analyzer manufactured by vinci technologies at the geochemistry laboratories of the turkish petroleum corporation (tpao). the analysis yielded several parameters, including s1, s2, s3, toc and tmax (tables 1, 2, 3). rock-eval pyrolysis was conducted using the rock-eval 6 analyzer manufactured by vinci technologies at the geochemistry laboratories of the turkish petroleum corporation (tpao). the analysis yielded several parameters, including s1, s2, s3, toc and tmax (tables 1, 2, 3). asian review of environmental and earth sciences, 2018, 5(1): 8-14 10 table-1. rock-eval pyrolysis data are tabulated for the naokelekan formation in the bj-1 well, north iraq no depth m toc % s1 (mg hc/g rock) s2 (mg hc/g roc) s3 (mg hc/g rock) pi tmax hi, mg hc/g toc oi, mg co2/g toc 1 2383 1 0.77 4.19 0.61 0.15 434 419 61 2 2384 1.11 0.83 4.55 0.38 0.15 434 410 34 3 2385 3.05 2.33 18.49 0.78 0.11 435 605 26 4 2386 2.88 1.17 10.5 0.72 0.1 435 365 25 5 2387 1.99 0.57 5.45 0.84 0.09 430 278 42 6 2388 1.12 0.4 3.78 0.66 0.1 435 338 59 7 2389 0.46 0.24 0.96 0.39 0.2 426 209 85 8 2391 5.26 0.99 24.47 1 0.04 441 465 19 9 2392 5.44 1.14 19.49 1.07 0.06 438 358 20 10 2393 2.26 0.68 8.15 0.77 0.08 438 361 34 11 2394 0.92 0.33 2.35 0.5 0.12 431 255 54 12 2401 22.89 2.02 119.72 2.97 0.02 441 523 13 13 2402 15.91 1.66 82.18 2.64 0.02 442 517 17 14 2403 13.64 1.47 68.02 2.87 0.02 441 499 21 15 2404 21.03 1.54 107.79 4.2 0.01 442 513 20 16 2405 19.35 1.36 91.79 3.41 0.01 440 474 18 17 2407 10.37 1.1 47.61 3.61 0.02 441 459 35 18 2409 13.3 1.47 67.92 2.18 0.02 442 511 16 19 2410 13.64 1.3 68.52 1.91 0.02 442 502 14 20 2411 11.96 1.4 64.62 2.08 0.02 442 540 17 21 2412 8.94 1.05 44.05 1.22 0.02 439 493 14 22 2413 6.07 0.86 29.19 1.39 0.03 439 481 23 23 2414 3.59 0.55 16.54 0.87 0.03 439 461 24 24 2432 1.19 0.3 2.07 0.6 0.13 437 174 50 25 2433 1.08 0.4 0.43 0.6 0.48 581 40 56 26 2434 3.39 0.88 1.21 0.83 0.42 583 36 24 27 2435 2.79 0.68 0.92 0.63 0.42 579 33 23 28 2436 7.67 1.09 2.81 0.85 0.28 585 37 11 29 2437 5.58 0.89 1.82 0.94 0.33 584 33 17 30 2438 9.91 1.03 2.91 1.35 0.26 594 29 14 31 2439 9.54 1.03 2.7 1.33 0.28 595 28 14 32 2440 3.42 0.65 0.87 0.88 0.43 597 25 26 33 2441 2.29 0.46 0.56 0.63 0.45 602 24 28 table-2. rock-eval pyrolysis data are tabulated for the naokelekan formation in the taq taq-1 well, north iraq no depth m toc% s1 (mg hc/g rock) s2 (mg hc/g rock) s3 (mg hc/g rock) pi tmax hi, mg hc/g toc oi, mg co2/g toc 1 2061 1.04 0.35 3.01 0.41 0.11 427 289 39 2 2063 3.65 1.61 16.05 0.82 0.09 429 440 22 3 2068 3.51 2 15.98 0.86 0.11 427 455 25 4 2072 4.16 6.92 28 1.31 0.2 344 673 31 5 2074 1.93 1.03 8.55 0.5 0.11 428 443 26 6 2077 1.4 0.85 4.2 0.75 0.17 423 300 54 7 2078 1.73 0.69 4.33 0.88 0.14 423 250 51 8 2088 1.43 0.52 2.59 1.16 0.17 425 181 81 9 2089 1.11 0.41 1.63 1.29 0.2 425 147 116 10 2090 1.62 0.66 4.8 1.22 0.12 429 296 75 table-3. rock-eval pyrolysis data are tabulated for the naokelekan formation in the jk-1 well, north iraq no depth m toc% s1 (mg hc/g rock) s2 (mg hc/g rock) s3 (mg hc/g rock) pi tmax hi, mg hc/g toc oi, mg co2/g toc 1 3219 0.95 0.1 0.09 0.54 0.51 419 9 57 2 3220 1.22 0.15 0.12 0.54 0.55 433 10 44 3 3221 0.85 0.1 0.27 0.68 0.27 433 32 80 4 3224 0.87 0.29 0.31 0.41 0.49 584 36 47 5 3225 1.04 0.23 0.27 0.89 0.46 595 26 86 6 3226 1.66 0.47 0.43 0.61 0.53 602 26 37 7 3230 0.85 0.32 0.41 0.59 0.44 445 48 69 a flame i̇onization detector (fid) was used to measure the concentration of organic compounds generated during pyrolysis. the first peak s1 represents hydrocarbons that can be thermally distilled from a rock. the second peak s2 represents hydrocarbons generated by the pyrolytic degradation of the kerogen in the rock. the third peak s3 stands for the carbon dioxide generated during temperature programming up to 390 °c, and is analyzed using a thermal conductivity detector (tcd). the hydrogen i̇ndex (hi) corresponds to the quantity of pyrolyzable organic compounds from s2 relative to the toc in the samples (mg hc/g toc) and can be successfully used to assess the oil generation potential of the rock and the type of organic matter. asian review of environmental and earth sciences, 2018, 5(1): 8-14 11 4. results and discussions pyrolysis techniques were used to establish the hydrocarbon potential and kerogen type as well as source rock type. 4.1. organic matter richness total organic carbon analysis (toc) describes the quantity of organic carbon in a rock sample including both kerogen and bitumen [9]. toc of naokelekan formation for bj-1 well show an excellent hydrocarbon potential (0.46-21.33%, with an average of 7.06%) and taq taq-1 well as good hydrocarbon potential (0.85-1.66 %, with an average of 1.06%), additionally jk-1 well show very good hydrocarbon potential (1.04-4.16 %, with an average of 2.15 %, tables 1, 2, 3). 4.2. organic matter types the term kerogen is to designate organic constituents of sedimentary rocks that are neither soluble in aqueous alkaline solvents nor in the common organic solvents [10]. all organic matter particles generated from phytoplankton, zooplankton, remains of bacteria, and higher plants have been recognized as the main contributors to kerogen in sediments [10]. the minor amounts of substances soluble in organic solvents associated with kerogen are collectively called bitumen. based on the rock-eval data (tables 1, 2, 3), source rocks can be characterized using the cross plot of toc versus hydrogen i̇ndex (hi) [11]. this plot showed that the naokelekan samples (well bj-1, biji oil field) have a fair to good oil source with mixed gas source. on the other hand, (well taq taq-1, taq taq oil field) is a gas source; while well jk-1 (jabal qand oil field) has a fair oil source (fig.2). fig-2. source rock characterization based on hi versus toc apdated after jackson, et al. [11] furthermore, the cross plot of toc versus s2, (fig.3) indicates that the kerogen of the naokelekan formation (well bj-1), is excellent to poor, taq taq-1 well is fair to good and jk-1 well is refer excellent to fair. fig-3. cross plot of tocwt% versus s2, shows the quantity of organic modified after hunt [12] asian review of environmental and earth sciences, 2018, 5(1): 8-14 12 the hydrogen i̇ndex (hi) versus oxygen i̇ndex (oi) based on rock-eval pyrolysis data (tables 1, 2, 3), can be plotted on a modified van krevelen diagram and interpreted [9]. it is observed from (fig.4) that type-i, ii is the dominant organic matter in the bj-1 well with few sample as type iv kerogen, while taq taq-1 and jk-1 well rock samples are represented by type-iv and -i/ii kerogens. fig-4. cross plot of oi versus hi for different kerogen types modified after hunt [12]; dembicki [13] 4.3. thermal maturity a source rock that has the possibility of producing a great amount of hydrocarbons is defined as mature. a source rock that lacks this ability is defined as immature, and that which passed the time of significant generation is define as over mature source rock [12]. the temperature at which the greatest amount of s2 is produced during pyrolysis is called tmax [13]. to avoid the influence of oi, we commonly used the cross plot of hi versus tmax to determine thermal maturity and kerogen type [12]. (fig.5) confirms that the naokelekan formation in the bj-1 well and taq taq-1 well is immature and lies within type-ii\iii, while jk-1 well samples are immature to over mature type-ii with few samples refer type iv kerogens. fig-5. hydrogen index (hi) versus tmax from espitalié, et al. [14]; dembicki [13] on the other hand, the thermal maturity of organic matter can be assessed through the combined relationship between tmax and the calculated production i̇ndex (pi) [15]. the cross plot of tmax versus pi (fig.6) shows that bj-1 well samples are range from mature to over mature, while taq taq-1 well are marginally mature to over mature. the majority of samples for jk-1 well are immature. asian review of environmental and earth sciences, 2018, 5(1): 8-14 13 fig-6. tmaxversus pi modified after langford and blank-valleron [15]; espitalié, et al. [14] 4.4. migrated hydrocarbons nonindigenous hydrocarbons can be detected, if s1 is high and the toc is low[15]. therefore, toc versus s1 diagram have been used to separates migrated from non-migrated hydrocarbons for the cutting samples taken from selected wells (fig.7). thus all the analyzed samples plot in indigenous hydrocarbons field, reflecting no external contribution of migrated hydrocarbons to the analyzed sample for selected wells. fig-7. plot of rock-evals1 versus toc (wt%) to distinguish indigenous from non-indigenous hydrocarbons from hunt [16]; hunt [12] 5. conclusions rock-eval pyrolysis data of naokelekan formation indicate a wide variation of source richness and quality, but all samples contain various quantities of type-i/ii, type-ii (oil prone) and type-iv (gas-prone) organic matter among the bj-1, taq taq-1 and jk-1 wells. hi for bj-1 well (24-605 mg hc/g toc), taq taq-1 (9-48 mg hc/g toc) and (147-673 mg hc/g toc) jk-1 which imply that the studied samples contain mostly type ii\iii for bj1, taq taq-1 and type ii with minor type iv. hioi diagram shows that kerogen type is mainly type-i\ ii for bj-1, type-iv with type -i/ii for taq taq-1 and jk-1 wells, while hi-tmax diagram classifies that the naokelekan formation in the bj-1 well and taq taq-1 well is immature and lies within type-ii\iii, while jk-1 well samples are immature to over mature type-ii with few samples refer type iv kerogen. references [1] j. k. pitman, d. steinshouer, and m. d. lewan, "petroleum generation and migration in the mesopotamian basin and zagros fold belt of iraq result from a basin-modeling study," gulf petrolink bahrain, vol. 9, pp. 41-72, 2004. view at google scholar [2] b. p. tissot and d. h. welte, petroleum formation and occurrence: a new approach to oil and gas exploration , 2nd ed. vol. 699. berlin: springer-verlag, 1984. [3] t. buday, the regional geology of iraq: stratigraphy and palaeogeography. baghdad: state organization for minerals, 1980. [4] a. s. al-sharhan and a. e. m. nairn, sedimentary basins and petroleum geology of the middle east. amsterdam: elsevier, 1997. [5] p. r. sharland, r. archer, d. m. cassey, r. b. davies, s. h. hall, a. p. heward, a. d. horbery, and m. d. simmons, arabian plate sequence stratigraphy, 371 ed. bahrain: gulf petrolink, 2001. [6] a. a. m. aqrawi, j. c. goff, a. d. horbury, and f. n. sadooni, the petroleum geology of iraq. beaconsfield: scientific press ltd, 2001. [7] r. m. pollastro, a. s. karshbaum, and r. g. viger, "map showing geology, oil and gas fields, and geologic provinces of the arabian peninsula," us geological survey, open file report 97-470b1999. https://scholar.google.com/scholar?hl=en&q=petroleum%20generation%20and%20migration%20in%20the%20mesopotamian%20basin%20and%20zagros%20fold%20belt%20of%20iraq%20result%20from%20a%20basin-modeling%20study asian review of environmental and earth sciences, 2018, 5(1): 8-14 14 [8] r. c. bellen, h. v. van dunnington, r. wetzel, and d. m. morton, luxique stratigraphique international. iraq, paris: asie, fascicule10a, 1959. [9] k. e. peters and m. r. cassa, "applied source-rock geochemistry. in: magoon, l.b., dow, w.g. (eds.), the petroleum system– from source to trap," american association of petroleum geologists memoir, vol. 60, pp. 93-120, 1994. [10] b. p. tissot and d. h. welte, petroleum formation and occurrence, 2nd ed. berlin, heidelberg: springer-verlag, 1984. [11] k. s. jackson, p. j. hawkins, and a. j. r. bennett, "regional facies and geochemical evaluation of southern denison trough," apea journal, vol. 20, pp. 143-158, 1985. view at google scholar | view at publisher [12] j. hunt, petroleum geochemistry and geology. newyork, usa: freeman and company, 1996. [13] h. j. dembicki, "three common source rock evaluation errors made by geologists during prospect or play appraisals," american association of petroleum geologists bulletin, vol. 93, pp. 341-356, 2009. view at google scholar | view at publisher [14] j. espitalié, j. l. la porte, m. madec, f. marquis, p. leplat, j. paulet, and a. boutefeu, "rapid method for the characterization of source rocks, their oil potential and their degree of evolution," journal of the french institute of oil, vol. 32, pp. 23-42, 1977. view at google scholar [15] f. f. langford and m. m. blank-valleron, "interpretation of rock-eval pyrolysis data using pyrolyzable hydrocarbons vs. total organic carbon," american associations of petroleum geologists bulletin, vol. 74, pp. 799-804, 1990. view at google scholar | view at publisher [16] j. m. hunt, petroleum geochemistry and geology vol. 743. new york: w. h. freeman and company, 1995. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://scholar.google.com/scholar?hl=en&q=regional%20facies%20and%20geochemical%20evaluation%20of%20southern%20denison%20trough http://dx.doi.org/10.1071/aj79013 https://scholar.google.com/scholar?hl=en&q=three%20common%20source%20rock%20evaluation%20errors%20made%20by%20geologists%20during%20prospect%20or%20play%20appraisals http://dx.doi.org/10.1306/10230808076 https://scholar.google.com/scholar?hl=en&q=rapid%20method%20for%20the%20characterization%20of%20source%20rocks,%20their%20oil%20potential%20and%20their%20degree%20of%20evolution https://scholar.google.com/scholar?hl=en&q=rapid%20method%20for%20the%20characterization%20of%20source%20rocks,%20their%20oil%20potential%20and%20their%20degree%20of%20evolution https://scholar.google.com/scholar?hl=en&q=interpretation%20of%20rock-eval%20pyrolysis%20data%20using%20pyrolyzable%20hydrocarbons%20vs.%20total%20organic%20carbon http://dx.doi.org/10.1306/0c9b238f-1710-11d7-8645000102c1865d 79 © 2020 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 7, no. 1, 79-86, 2020 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2020.71.79.86 © 2020 by the authors; licensee asian online journal publishing group assessment of environmental impacts of limestone exploitation in igarra, nigeria ogundele j.o.1 olotu .y.2 parker-ikharo f.3 sanni e.b.4 yusuf i.5 eremiokhale, j.i6 ( corresponding author) 1,4,5department of mineral & petroleum engineering technology, auchi polytechnic, auchi, nigeria. 2department of agricultural engineering, auchi polytechnic, auchi, nigeria. 3department of civil engineering, auchi polytechnic, auchi, nigeria. 6department of architectural technology, auchi polytechnic, auchi, nigeria. abstract the exploration of limestone is the nerve of socio-economic integration of the igarra community. however, the exploration activities have been linked with several adverse effects on human health and the deterioration of the surrounding environment. this research work investigates the quality of air in the study area. dust emission was measured using a digital air quality monitor of model hp 5800d pm2.5-10 with an accuracy of ±5% or ±4ug/m3 and measuring and detection ranges of 0.3 ug/m3 and 0-999.9 ug/m3. the dust level readings using pm2.5 and pm10 at 1 km apart from the three selected exploration sites in igarra at a 60-minute interval was taken. quarry one (q1) recorded the lowest dust level of 20.6 μg//m3 for pm2.5 and 72.5 μg//m3 for pm10 in the early hours before exploration. the general outputs show that exploration sites (q2) and (q3) produced a high degree of polluted air than site q1. a higher dust level of 966.0μg/m3 was recorded for pm10. the overall dust level measurements for pm2.5 and pm10 are higher than the recommended 70.0-80.0 μg/m3 by the world health organization (who) and the environmental protection agency (epa). it is projected that continuous emission of dust at igarra could lead to an increasing number of diseases such as asthma, catarrh, and breathing problems. in conclusion, an integrated exploration mechanism is essential to improve air quality and substantially reduce air related pollution. keywords: limestone, dust emission, pm2.5-10, environment, igarra. citation | ogundele j.o.; olotu .y.; parker-ikharo f.; sanni e.b.; yusuf i.; eremiokhale, j.i (2020). assessment of environmental impacts of limestone exploitation in igarra, nigeria. asian review of environmental and earth sciences, 7(1): 79-86. history: received: 29 october 2020 revised: 17 november 2020 accepted: 7 december 2020 published: 22 december 2020 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 80 2. methodology .................................................................................................................................................................................... 80 3. results and discussion ................................................................................................................................................................... 82 4. conclusion ......................................................................................................................................................................................... 86 references .............................................................................................................................................................................................. 86 https://www.asianonlinejournals.com/index.php/arees/article/view/2474 http://crossmark.crossref.org/dialog/?doi=10.20448/journal.506.2020.71.79.86&domain=pdf&date_stamp=2017-01-14 http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ asian review of environmental and earth sciences, 2020, 7(1): 79-86 80 © 2020 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes to existing literature by investigating the quality of air in the study area. dust emission was measured using a digital air quality monitor of model hp 5800d pm2.5-10 with an accuracy of ±5% or ±4ug/m3 and measuring and detection ranges of 0.3 ug/m3 and 0-999.9 ug/m3. 1. introduction the exploitation of mineral resources has assumed prime importance in several developing countries, including nigeria. nigeria is endowed with abundant mineral resources, contributing immensely to the national wealth with associated socio-economic benefits. mineral resources are an essential source of wealth for a nation, but before they are harnessed, they have to pass through the stages of exploration, mining, and processing [1] natural resources can be classified into two groups: renewable and non-renewable resources. renewable natural resources are replenished on short time scales of a few months or years—for example, wind, hydraulic and solar energies. nonrenewable resources are contained in the earth in fixed quantities and are not replenished by natural processes operating on short time scales [2, 3]. examples are oil, natural gas, coal, metals, and mineral products produced from the earth. the formation period of oil, gas, metals, and minerals is very long (i.e., over tens of millions of years), vastly slower than the rates at which we mine these materials. the resources we obtain from the earth's crust today are products accumulated over the last billions of years. most non-renewable natural resources are also mineral resources, both organic and inorganic in origin. resources can also be classified into three major use groups: metallic, energy, and non-metallic mineral resources [1]. nigeria's environment (at urban and rural levels) has suffered an accelerated decline in air quality, soils, biodiversity, and water resources [4]. it is clear that sound natural resources management and planning are essential to tackling the problems above and to promote sustainable development [4, 5]. mining activities represent human actions that cut through the landscape, scarring, and interfering with the natural habitat conditions as well as micro-climatic conditions. specifically, the environmental effects of limestone mining and cement production are known to impoverish flora and fauna of host environment, result in sediments deposition in riverine systems, create mining spoil mounds and deep mining lakes mainly, result in loss of timber resources and another vegetal cover, toxification, and pollution due to chemical wastes or weathering of mining spoils, cause changes in micro-climate, and several others [2, 6]. these effects on the ecosystem are not only on-site but also occur off-site as well. these, in turn, significantly alter the environmental spheres of the affected areas. quarrying is obtaining quarry resources; usually, rocks are found on or below the land surface. quarrying generates a lot of particulate matter (dust) with a diameter of 1-75 μm (micron) [7, 8]. particles with aerodynamic diameters of less than 50 μm (termed total suspended particulate matter, or tsp) can become suspended in the atmosphere, and those with aerodynamic diameters of less than ten μm termed pm10 (inhalable particles) can be transported over long distances and enter the human respiratory system [9, 10]. many researchers have reported these processes to have responsibility for several health problems. 2. methodology 2.1. study area the study area is located at igarra in akoko edo local government of edo-state, nigeria. figure 1 shows the map of nigeria, edo state and the study area (igarra). table 1 shows the codes used in describing the sampling sites. igarra is located between latitudes 07º 08 16 and 07º 31 58, and longitudes 08º 37 46 and 09º 10 31. the study area is located within a sub-humid tropical region with mean annual temperature ranging from 29ºc to 30ºc, and is characterized by two distinct seasons: the dry season and rainy season. the mean annua1 precipitation is about 1,370mm, with an average wind speed of 1.50 m/s. 2.2. experimental design data on the impact of limestone mining (extraction) activities on the com-munities in the study area (igarra) were collected using two methods known as primary and secondary data collections. i. primary data collection: this involved measurement of air quality/ dust level using digital particulate matter instrument (pm2.5). ii. secondary data collection: data collected from health records in the clinics/hospital most patronized by the people. social survey was also conducted by questionnaire administration in the communities sampled. 2.2.1. descriptions of particulate matter (pm2.5 and pm10) the instrument is an of high-tech air quality to measure the pm2.5 and pm10. it uses a laser pm2.5 sensor, single-chip microcomputer technology and high visibility dot matrix lcd. this instrument is of high precision, short measuring time, stable performance, strong function, easy operation, low power consumption, with function of time display, real time measurement very suitable for indoor and outdoor environment monitoring, can also be used in the detection of air purification machine to air purification effect. the instrument is shown in figure 2 and 3. 2.2.2. measurement of particulate matter (pm2.5 and pm10) pm2.5/10 was used to monitor air quality (µ/mg) at igarra near freedom quarry for 10-day. pm2.5/10 was sampled for a period of 6-hour at 30 minutes intervals per day. measured dust levels at every interval were recorded. pm10 was empirically estimated using equation 1: (1) pm10 = particles with aerodynamic diameter of 10 microns. m1 = weight of filter paper before sampling (g). m2 = weight of filter paper after sampling (g). fr = average flow rate (l/min or m3/min). asian review of environmental and earth sciences, 2020, 7(1): 79-86 81 © 2020 by the authors; licensee asian online journal publishing group t = sampling duration in minutes [2]. pm2.5 and pm10 was calibrated using the expression in equation 2. (2) figure-1. map of study area. source: esmhw [11]. figure-2a. air quality monitor. source : salvi and holgate [12]. figure-2b. dust level measurement. source: field work, 2018. asian review of environmental and earth sciences, 2020, 7(1): 79-86 82 © 2020 by the authors; licensee asian online journal publishing group 2.2.3. climate variables field climatic parameters (minimum and maximum temperature, relative humidity) of the study area were measured with digital thermometer model cx 201a. current climatic data (1975-1985) and (1990-2005) were obtained from nigerian meteorological agency (nmet). future projected climatic data (2030-2045) of igarra was downscaled using centre of canadian climate modelling & analysis (cccma) under representative concentration pathways (rcp 4.5). 2.2.4. health and agricultural data collection structural questionnaires were used to obtained health and agricultural information in the study area. these data were collected to establish the relationship between exploration activities and the health of the dwellers and also to determine the link between quarrying activities and crop yield as indicated in table 1. table-1. code for the sampling of study area. area code sampling sites q1 exploration site 1 q2 exploration site 2 q3 exploration site 3 3. results and discussion 3.1. dust level measurement digital air quality monitor was used to measure and evaluate particle concentration variations within a pre-set time interval. tables 2-4 show the results of dust level measurement using pm2.5 and pm10 from three limestone exploration sites at igarra. the measurement was carried at a 30-minute interval for 6-hour daily. it is observed that q1 recorded lowest dust level of 19.6 μg/m3 for pm2.5, 59.6 μg/m3 and 62.5 μg/m3 for the pm10. this indicates that the air quality is good and healthy around this period. the result is in agreement of najime, et al. [9]; musa and jiya [10]; yoon and brimblecombe [13]. the concentration dust particle starts to rise between 10.00 am to 10.30 am and reduced to 56.6 μg/m3 which corresponds to 365μg/m3 for pm10. the highest concentration of 529.1 μg/m3 and 864.3 for pm2.5 and these values correspond to 0.0μg/m3, 3280.0μg/m3 and pm10 and estimated pme10 respectively (table 2 and figures 3-4). the maximum dust level measurement for digital dust monitor hp 5800d pm-10 is 9990μg/m3, based empirical equation was applied to compute the values that could not be easily monitored from the digital equipment. 0.0μg/m3 indicates out of measurement range for pm10. the overall results show that exploration site two and three produced a high degree of dust. dust level of 5917.2μg/m3 was generated from pme10 which corresponds to 0.0μg/m3 and 906.0μg/m3 of pm10 and pm2.5 (figures 2-5; table 3). the results are similar to previous studies [1, 4, 9]. table-2. dust level reading in exploration one (q1). time (mins) duration pm2.5 (ug/m3) pm10 (ug/m3) 9.30 0.00-30.0 19.6 59.5 10.00 30.0-60.0 126.0 739.3 10.30 60.0-90.0 143.9 892.2 11.00 90.0-120.0 56.6 365.5 11.30 120.0-150.0 529.1 0.0 12.00 150.0-180.0 19.8 119.8 12.30 180.0-210.0 10.8 61.3 1.00 210.0-240.0 143.9 892.2 1.30 240.0-270.0 99.6 685.6 2.00 270.0-300.0 92.2 513.4 2.30 300.0-330.0 24.1 178.8 3.00 330.0-360.0 864.3 0.0 table-3. dust level reading in exploration site two. time (min) duration pm2.5 (ug/m3) pm10 (ug/m3) pme10 (ug/m3) 8.00 0.00-30.0 75.4 529.2 696.2 8.30 30.0-60.0 99.6 685.6 785.6 9.00 60.0-90.0 139.5 828.5 988.5 9.30 90.0-120.0 92.2 513.4 767.4 10.00 120.0-150.0 24.1 178.8 199.8 10.30 150.0-180.0 906.0 0.0 5617.2 11.00 180.0-210.0 864.3 0.0 5358.7 11.30 210.0-240.0 674.7 0.0 4183.1 12.00 240.0-270.0 99.6 685.6 889.6 12.30 270.0-300.0 126.0 59.5 70.5 1.00 300.0-330.0 143.9 0.0 892.2 1.30 330.0-360.0 19.8 169.8 199.8 asian review of environmental and earth sciences, 2020, 7(1): 79-86 83 © 2020 by the authors; licensee asian online journal publishing group figure-3. comparison of pm 10 results measured from three quarry sites (q1-q2 however, quarry (3) shown the similar increasing trend of dust level as in quarry (2). q3 recorded higher values both at 11.00 am (180.0-210.0) and 11.30 am (210.0-240.0) and least unhealthy air of 80.6 μg/m3,499.7 μg/m3 and 599.7 μg/m3 for pm2.5, pm10 and pme10 respectively. the higher particulate matter (pm) shows the peak of limestone exploration activities during the day figure 5. 3.2. the impact of climate on dust concentration figure-4. comparison of pm 2.5 results measured from three quarry sites (q1-q2-q3). the weather data was taken in-situ along with dust level. the results show that the climate is very warm in all the quarry sites with the minimum temperature from 26.40c to 27.7oc and maximum temperature from 37.8oc to 40.1oc for q3, q2 and q1 respectively. however, q3 has a higher relatively relative density of 57.0% over q2 and q1(table 4). during the dry season (warmer climate) the air moisture content is very low and this allows dust to be accumulated and easily dispersed, whereas dust particles are being trapped during the wet season. tables 5-6 show the baseline climate of the study area for before and during the limestone exploration. the result of the future projected climate of igarra using centre of canadian climate model & analysis under the climate change scenario (rcp 4.5). table-4. annual average climate data of ikpeshi during pre-limestone exploration(1970-1985). year tmin(oc) tmax(oc) prec(mm) 1970 19.0 31.0 1111.3 1971 19.9 31.5 1228.0 1972 20.3 31.7 1367.2 1973 20.0 31.9 1306.6 1974 19.1 32.3 1091.8 1975 18.5 30.8 1393.0 1976 20.1 31.0 1172.9 1977 19.7 31.6 1352.2 1978 19.1 31.5 1053.4 1979 20.1 31.3 1309.8 1980 20.1 31.7 1278.8 1981 19.0 31.3 1091.0 1982 20.2 31.9 1254.3 1983 20.5 31.9 1394.4 1984 20.6 31.8 1222.4 1985 19.0 31.2 1230.8 source: yoon and brimblecombe [13]. asian review of environmental and earth sciences, 2020, 7(1): 79-86 84 © 2020 by the authors; licensee asian online journal publishing group table-5. annual average climate data of ikpeshi during limestone expliotation (1990-2005) year tmin(oc) tmax(oc) prec(mm) 1990 19.8 32.8 1435.1 1991 26.1 32.1 1508 1992 20.5 32.2 1138 1993 18.7 31.4 1258.8 1994 19.5 31.6 1393.6 1995 19.8 32.3 1269.7 1996 21.3 33 1001.2 1997 20 33.1 1071.2 1998 19.2 32.1 1115.4 1999 18.6 31.8 1250.3 2000 20.2 32.5 1216.6 2001 20.7 32.6 1464.1 2002 20.9 33 1005.5 2003 19.8 32.5 1326.2 2004 20.2 32.7 1417.3 2005 19.8 32.6 1321.9 source: yoon and brimblecombe [13]. figure-5. climatic (temp) analysis of study area during pre-limestone exploration. figure-6. climatic (temp) analysis of study area during prelimestone exploration. source: sensitivity analysis, 2018 table-6. annual average climate data of ikpeshi during limestone expliotation (2030-2045) year tmin(oc) tmax(oc) prec(mm) 2030 20.1 30.3 1387.8 2031 25.7 31.1 573 2032 25.5 30.7 2105.8 2033 26.1 31 1920.7 2034 25.9 31.6 151.4 2035 25.5 30.9 1641.9 2036 26.7 28.7 1595.9 2037 26 291.9 1609.2 2038 26.2 31.3 1606.2 2039 25.7 31 1636.9 2040 26.1 31.3 2007 2041 26.7 31.6 1547.2 2042 26.5 31.3 1705.1 2043 25.8 30.2 1531 2044 26.2 31 1743.6 2045 26.1 31.7 1764.4 asian review of environmental and earth sciences, 2020, 7(1): 79-86 85 © 2020 by the authors; licensee asian online journal publishing group figure-7. climatic (temp) analysis for projected (temp) from cccma-rcp 4.5 for the study area. it is clear that tmax increased with 0.120c per year from 1985 to 2010 and this trend is projected with marginal increase of 0.06770c annually for the period 2028 to 2046, while increase of 0.32oc was projected for the minimum temperature figures 6-8. any large-scale impacts of dust on atmospheric temperatures in these periods would have potentially important implications for atmospheric stability and ultimately for the ability of the atmosphere to foster conditions conducive to rainfall generation. dust is a major natural source of atmospheric aerosols that can potentially affect clouds. the effect of dust concentration on precipitation was not known before the trmm satellite was launched and applied to clouds forming in dust-laden air [6, 7]. the large sizes of some of these dust particles had led to the assumption that dust would enhance precipitation rather than decrease it. the result of rainfall analysis in figures 8-9 indicate variation of rainfall distribution before, during and projected future climate in the study area. figure-8. precipitation analysis during pre-limestone exploration era figure-9. precipitation analysis during limestone exploration era 3.3. dust concentration and human health dust is a common air pollutant. dust particles vary in size from coarse (non-inhalable), to fine (inhalable), to very fine (respirable). coarse dust particles generally only reach as far as the inside of the nose, mouth or throat. smaller or fine particles, however, can get much deeper into the sensitive regions of the respiratory tract and lungs. these smaller dust particles have a greater potential to cause serious harm to your health. the potential health effects of some common dusts in mines and quarries are analysed as shown in figure 10. figure-10. health conditions of the dwellers of study area. the results of the analysis indicate that four out of six most commonly reported diseases in igarra are dustpollution related diseases. above 50% of the respondents claimed to have suffered asthmatic attacks, while over 60% and above have suffered catarrh, difficult breathing and headache respectively. however, 28% of heart attack cases had been reported. in most cases each of the diseases goes along with malaria parasites. in addition, the most common symptoms experienced during a dust storm are irritation to the eyes and upper airways infants, young children and the elderly are most vulnerable. asian review of environmental and earth sciences, 2020, 7(1): 79-86 86 © 2020 by the authors; licensee asian online journal publishing group 4. conclusion the study of limestone exploration on the prevailing climate of igarra was carried out by measuring the air pollution of the study area with pm2.5 and pm10 at 30 minutes interval respectively. empirically-based model was also used to compute pm10 in order to create robust dataset since the digital air monitor was not calibrated to measure above 999.0(μg/m3). results from annual pm2.5-10 and pme10 data confirm the air quality in the study zones is highly hazardous to human health and this may probable the result of high cases of illness in the region. the implication is that the observed daily average values of both pm2.5 and pm10 are higher than the who and 70 μg/m3 set by epa, permissible limits for all stability classes. additionally, results confirm the interdependent importance of relative humidity, minimum and maximum temperature in pm2.5-10 concentration from igarra. effects of variability of precipitation (distribution and intensity) should also be considered. the output of the health analysis shows deadly effects of limestone exploration activities on the dwellers in igarra. there has been a sharp rise in dust and water related or borne diseases since the advent of limestone mining commenced in igarra and its environs. water resources (surface and underground) have been polluted and this has made safe drinking water unavailable and inaccessible. moreso, the settling of dust particle on the roof surface of most homes further complicate rain harvesting system. references [1] i. aigbedion, "environmental pollution in the niger-delta, nigeria," inter-discplinary j. enugu-nigeria, vol. 3, pp. 205–210, 2005. [2] e. acheampong, "impact assessment of mining activities by ashanti goldfields, bibiani limited on the environment and socioeconomic development of bibiani," undergraduate dissertation, faculty of social sciences, kwame nkrumah university of science and technology, 2004. [3] j. i. d. adekeye, the impact of artisanal and illegal mining on the environment in nigeria: elizabethan publishing co, 1976, 2001. [4] j. a. adekoya, "environmental effect of solid minerals mining," journal of physical science, vol. 45, pp. 625–640, 2003. [5] d. cameron, e. l. bartlett, j. s. coats, d. e. highly, g. k. lott, d. flight, j. hillier, and harrison, directory of mines and quarries 2002, 6th ed. nottingham: british geological survey, 2002. [6] d. ajakaiye, "environmental problems associated with mineral exploitation in nigeria," presented at the a paper presented at the 21st annual conference of the nigeria mining and geosciences society held at jos, 1985. [7] t. najime, "cretaceous stratography, sequence and techno-sedimentary evolution of gboko area, lower benue trough nigeria," unpublished ph.d thesis, department of geology, ahmadu bello university zaria, nigeria, 2010. [8] o. a. kogbe ca, statistics of mineral production in nigeria (1916 1974) and contribution of the mineral industry to the nigeria economy. in c.a. kogbe (ed.) geology of nigeria. lagos nigeria: elizabethan publishing co, 1976. [9] t. najime, p. m. zaborski, and s. i. abaa, "allocyclic control on the depositional sequence of the gboko formation, lower benue trough," borno journal of geology, vol. 4, pp. 56-69, 2006. [10] h. d. musa and s. n. jiya, "an assessment of mining activities impact on vegetation in bukuru jos plateau state nigeria using normalized differential vegetation index (ndvi)," journal of sustainable development, vol. 4, pp. 150-159, 2011.available at: https://doi.org/10.5539/jsd.v4n6p150. [11] esmhw, "categorization of agro-ecological zones in edo state," bulletin, vol. 6, p. 71, 2007. [12] s. salvi and s. t. holgate, "mechanisms of particulate matter toxicity," clinical and experimental allergy, vol. 29, pp. 1187-1194, 1999.available at: 10.146/j.1365-2222.1999-00576.x. [13] y. h. yoon and p. brimblecombe, "the distribution of soiling by coarse particulate matter in the museum environment," indoor air, vol. 11, pp. 232-240, 2001. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 6 © 2025 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 12, no. 1, 6-13, 2025 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v12i1.6917 © 2025 by the authors; licensee asian online journal publishing group unsolved problems in the study of coal formation processes and the manifestation of hazardous properties of coal seams filatieva elvira1 filatiev mikhail2 antoshchenko nikolay3 fursova olha4 maksyuk inna5 ( corresponding author) 1department of fire safety, vladimir dahl lugansk state university, ukraine. 1email: elafilatyeva@gmail.com 2,3,4,5department of technosphere safety, lugansk state university, ukraine. 2email: mfilatev@gmail.com 3email: antm1949@gmail.com 4email: metmashdtu@gmail.com 5email: innagroys@gmail.com abstract to establish problems, the solution of which for a specific stage of coal formation will allow a scientifically sound prediction of the occurrence and manifestation of hazardous properties of a specific coal seam during mining operations. the methodology is based on modern concepts of coal formation processes to confirm or establish the discrepancy between the processes occurring at different stages. hazardous properties of coal seams during mining operations are formed not only at the stage of metamorphic transformations, and their occurrence is genetically associated, to a large extent, with previous processes of accumulation of the source material, which was subjected to successive transformation at the peat, brown coal, coal, or anthracite stages of coal formation. based on the conducted research, scientifically substantiated proposals have been developed to clarify the general scheme of coal formation, which significantly changes the understanding of the formation of hazardous properties of mine seams and indicates the need to solve a number of urgent scientific problems associated with improving the regulatory framework for safe mining operations and clarifying geological processes at individual stages of coal formation. keywords: coal formation, hazardous properties, problems, processes, regulatory frameworks, safety. citation | elvira, f., mikhail, f., nikolay, a., olha, f., & inna, m. (2025). unsolved problems in the study of coal formation processes and the manifestation of hazardous properties of coal seams. asian review of environmental and earth sciences, 12(1), 6–13. 10.20448/arees.v12i1.6917 history: received: 5 may 2025 revised: 12 june 2025 accepted: 27 june 2025 published: 18 july 2025 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support institutional review board statement: not applicable. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. this study followed all ethical practices during writing. competing interests: the authors declare that they have no competing interests. authors’ contributions: all authors contributed equally to the conception and design of the study. all authors have read and agreed to the published version of the manuscript. contents 1. introduction ......................................................................................................................................................................................... 7 2. materials and methods ...................................................................................................................................................................... 7 3. results and discussion ...................................................................................................................................................................... 7 4. conclusions ....................................................................................................................................................................................... 12 references .............................................................................................................................................................................................. 12 mailto:elafilatyeva@gmail.com mailto:mfilatev@gmail.com mailto:antm1949@gmail.com mailto:metmashdtu@gmail.com mailto:innagroys@gmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v12i1.6917 https://orcid.org/0000-0002-1041-0535 https://orcid.org/0000-0001-5608-6737 https://orcid.org/0000-0001-8901-8263 https://orcid.org/0000-0002-9622-2622 https://orcid.org/0000-0002-0096-7372 asian review of environmental and earth sciences, 2025, 12(1): 6-13 7 © 2025 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the possibilities of forming dangerous properties of coal seams are considered not only at the stage of metamorphic transformations but also in relation to their occurrence, which is genetically connected with previous processes of accumulation of the initial material, subjected to successive transformations at different stages of coal formation. 1. introduction the hazardous properties of coal seams (release of flammable and explosive gases, sudden outbursts of coal and gas, occurrence of endogenous fires, increased dust formation and its explosiveness, and some other features) during mining operations are considered in modern regulatory documents depending on the degree of metamorphic transformations of coals. as one of the main indicators of the degree of metamorphism and, in most cases, the only one, the yield of volatile substances (mass or volume) during thermal decomposition of coals without access to air is accepted [1-7]. in essence, the indicators 𝑉𝑑𝑎𝑓and 𝑉𝑣 𝑑𝑎𝑓 , according to the methods of their laboratory determinations based on analytical samples of coal, they are a mixture of gaseous fluids released from dry ash-free mass under artificially created conditions with elevated temperature. the mixture of gases released during the thermal destruction of coal has no direct relation to the occurrence of hazardous properties of coal seams. fluids, including moisture, which determine hazardous properties during mining operations, have already been removed at the stage of preparing analytical samples by crushing to a size of 7 μm and drying the coal at a temperature above 100℃ [8]. for this reason, the influence on the occurrence and manifestation of hazardous properties of seams should be considered regardless of the indicators 𝑉𝑑𝑎𝑓or 𝑉𝑣 𝑑𝑎𝑓 , but on the elemental composition of coals and fluids that were formed and preserved (including possibly only partially) during geological processes before mining operations. 2. materials and methods it follows from the state of the issue under consideration that problems related to the reliable prediction of hazardous properties of coal seams during mining operations have not been fundamentally resolved to date. this is confirmed by the ongoing and periodically recurring accidents at enterprises in coal-mining countries around the world caused by gas flares and explosions in mine workings, sudden emissions of coal and gas in production and development faces, the occurrence of endogenous fires, and some other manifestations of hazardous properties. prevention of such accidents largely depends on the degree of validity of the requirements of regulatory documents governing the safe operation of coal deposits. the effectiveness of measures taken to prevent accidents depends on the reliability of forecasts regarding the hazardous properties of mine seams. therefore, research aimed at improving the regulatory framework for safe mining operations remains highly relevant for all coal-mining countries worldwide. 3. results and discussion the formation of methane and carbon dioxide at the peat stage could not have significantly influenced the formation of the hazardous properties of coal seams, since their release occurred almost entirely into the atmosphere. water formation did not occur at the peat and brown coal stages, since geological transformations of the initial substance at the diagenesis stages consisted only of its removal. similar processes of only moisture removal continued at the carboniferous stage, which refers to metamorphic transformations. the absence of water formation processes at the carboniferous stage is confirmed by experimental data on the graphs of the decrease in maximum moisture capacity and stable hydrogen content (≈ 4.5÷5.5%) depending on carbon in the range of its change from approximately 75 to 88% (figure 2). figure 1. dependence of the maximum moisture capacity of coal seams (a) and the hydrogen content in the combustible part of the fuel (b) on carbon for hard coals and anthracites. note: 1 – averaging curves; × – experimental data on maximum moisture capacity according to handbook of the quality [9]; ● – joint experimental data on coal moisture in coal seams according to catalogue [1] and carbon content in the combustible part according to data from handbook of the quality [9](a); ×experimental data on hydrogen content according to reference book [10]; 𝑅2, σ – coefficients of determination and standard deviation, respectively. asian review of environmental and earth sciences, 2025, 12(1): 6-13 8 © 2025 by the authors; licensee asian online journal publishing group the transition to the anthracite stage is characterized by a carbon content of more than 88% and an increase in moisture capacity after reaching minimum values (figure 1a). the possibility of the formation and release of water at the anthracite stage is additionally indicated by a decrease in hydrogen content, also at a carbon content of more than 88% (figure 1b). the ambiguous change in moisture content in coals allows the break in the curve, from decreasing to increasing, to be considered as the beginning of the anthracite stages of metamorphism [11]. using only the indicators of the degree of metamorphic transformations, including 𝑉𝑑𝑎𝑓and 𝑉𝑣 𝑑𝑎𝑓 , it is impossible to reliably predict the gas content of coal seams in advance (figure 2). its quantitative values are random quantities, since the total amount of gases formed at individual stages of coal formation and their share subsequently released into the host rocks or onto the earth's surface are not taken into account. figure 2. dependence of gas content of donbass mine seams (ch4) on the yield of volatile substances ( 𝑉𝑑𝑎𝑓) according to statistical processing. note: 1,2 – respectively, the upper and lower boundaries of the change in the gas content of anthracites according to the joint data processing [12-14]; 3 – the expected lower boundary of the gas content during the transition from hard coals to anthracites; 4,5 – respectively, the upper and lower boundaries of hard coals; 6 – the averaging rectilinear boundary of the maximum values of gas content according to the results of data processing [13]; 7 – the conditional boundary of the division of hard coals by the degree of metamorphism into two parts, respectively, with an increase and decrease in gas content; i , ii , iii – gas content zones, respectively, for anthracites, transition and hard coals; ● – experimental data obtained during the joint data processing [1, 15]. source: antoshchenko and shepelevich [16]. if conditions exist for the removal of all formed gases, then the methane content of coal seams is quantitatively equal to zero. if some part is retained, the maximum gas content of anthracite coal seams can reach 45 m3 per ton of dry ash-free combustible mass (m3/tdacm), and that of coal seams 35 m3/tdacm. this difference indirectly confirms that at the anthracite stages, some additional methane is formed under the influence of elevated temperature. the formation of carbon dioxide (co2) in significant quantities at the coal and anthracite stages is unlikely. this conclusion follows from the graph showing the decrease in the average oxygen content alongside a simultaneous increase in carbon in the combustible part of the fuel as the degree of metamorphic transformations increases (figure 3). figure 3. dependence of oxygen content on carbon content for coal and anthracite seams. note: 1 averaging curve; × experimental data [10]; r2 and σ respectively, the coefficients of determination and the standard deviation. asian review of environmental and earth sciences, 2025, 12(1): 6-13 9 © 2025 by the authors; licensee asian online journal publishing group table 1. results of statistical processing of experimental data [10] on the quantitative increase in carbon content (сг) and decrease in oxygen (ог) at individual stages of metamorphic transformations. s ta g es o f m et am o rp h ic t ra n sf o rm at io n s o f co al s an d a n th ra ci te s average carbon content гс , % average oxygen content го , % t h e d if fe re n ce b et w ee n t h e in cr ea se i n t h e av er ag e ca rb o n co n te n t an d th e d ec re as e in o x y g en , ∆ с г ∆ о г , % t h e m ai n co m p o n en ts o f th e co m b u st ib le m as s th at t o o k p ar t in t h e fo rm at io n o f fl u id s v it ri n it e re fl ec ta n ce v ar ia ti o n ra n g e r o, % n o te s a t th e b eg in n in g o f th e st ag e a t th e en d o f th e st ag e in cr ea se i n t h e co n te n t o f ∆ с г a t th e b eg in n in g o f th e st ag e a t th e en d o f th e st ag e r ed u ct io n o f co n te n t ∆ о г i 75.00 84.24 9.24 14.77 5.18 9.59 -0.35 ог 0.40÷1.06 transitional stage from brown coal to hard coal ii 84.24 87.83 3.59 5.18 2.89 2.29 1.30 ог, нг 1.06÷1.43 carboniferous stage iii 87.83 92.75 4.92 2.89 1.12 1.77 3.15 ог, нг, sг 1.43÷2.17 transitional stage from hard coals to anthracites iv-ix 92.75 97.23 4.48 1.12 0.39 0.39 3.75 ог, нг, sг, nг, сг 2.17÷3.54 anthracite stages x >97.23 -* -* <0.73 -* >3.75 -* >3.54 note: * no data. asian review of environmental and earth sciences, 2025, 12(1): 6-13 10 © 2025 by the authors; licensee asian online journal publishing group to establish a quantitative relationship between the increase in carbon content and the simultaneous decrease in oxygen in the combustible mass at each stage of metamorphic transformations, an empirical relationship was used [17]: с̄г = 100 − 33,1 ⋅ е−0,70⋅𝑅𝑜, % (1) where: с̄гand 𝑅𝑜are, respectively, the average carbon content in the combustible mass and the corresponding vitrinite reflectance index, %. dependence (1) is established on the basis of a generalization of experimental data obtained by different researchers. it practically functionally reflects the interdependence between the average carbon content and vitrinite reflection (r2 = 0.94). this allows us to compare the growth of carbon content and the decrease in oxygen in the combustible mass at each characteristic stage of metamorphic transformations (table 1). such stages were preliminarily determined by the intersection points of the averaging pairs of curves of the dependences of the main components (oxygen, hydrogen, organic sulfur, nitrogen) as the metamorphic transformations intensify (growth сг). each intersection point of two averaging curves indicates a change in the ratio between the content of the main components in the combustible (organic) mass, which undoubtedly affects the manifestation of hazardous properties of the mine layers. in this way, ten characteristic stages of metamorphic transformations of mine layers were established by the factor of changing the ratio between all the main components. their boundaries are clearly defined by the average carbon content and the sum of the remaining components. using the dependence of the average carbon content on the vitrinite reflectance (1), the ranges of change in the content of the main components at characteristic stages were also established by the vitrinite reflectance index (figure 4). this allowed us to separately consider the quantitative dependencies of the increase in the average carbon content and the decrease in oxygen at each characteristic stage of metamorphism by the factor of change in the elemental composition (table 1). the first stage is, to some extent, a transitional one from brown coals to hard coals (𝑅𝑜= 0.40 ÷ 1.06%). this follows from the upper limit of the vitrinite reflectance index (𝑅𝑜= 0.60%) for brown coals during their classification by genetic and technological parameters [18]. at the first stage, the increase in the average carbon content (∆сг) was due exclusively to the removal of oxygen (∆ог). the average possible quantitative increase in ∆сгwas 9.24%, and the decrease in ∆ог occurred by 9.59%. the difference between these indicators (0.35%) is within the permissible limits of accuracy for determining the desired values; therefore, other main components (hydrogen, organic sulfur, nitrogen) did not participate in the formation of fluids at this stage of metamorphism. figure 4. dependences of the average carbon content (a), the sum of the remaining main components of the combustible part (b) and their individual change (c) at different stages of metamorphic transformations on the vitrinite reflectance. note: 1,2 – averaging curves, respectively, of the dependences of the carbon content ( гс ) and the sum of the remaining main components (∑ ); 3,4,5,6 – averaging curves, respectively, of the dependences of the individual content of oxygen (о̄г), hydrogen ( н̄г), sulfur ( гs ) and nitrogen ( гn ); 1′,2′,3′,4′-9′ intersection points of the averaging curves of the individual change in each main component of the combustible part; i, ii, iii, iv, v, vi, vii, viii, ix, x stages of metamorphic transformations, distinguished by the average content of the main components. the second stage is characterized by the transformation of only coal seams (𝑅𝑜= 1.06 ÷ 1.43%). at this stage, the growth of carbon content (∆сг= 3.59%) somewhat outpaces the reduction of oxygen (∆ог= 2.29%), which indicates the possible participation of other main components in the formation of fluids. based on the graph of the experimental data (figure 1b), the formation of fluids at this stage also occurred due to the reduction of the elemental content of hydrogen in the combustible mass. the upper limit of the carbon content at stage ii (87.83%) , , ,г г г го н n s asian review of environmental and earth sciences, 2025, 12(1): 6-13 11 © 2025 by the authors; licensee asian online journal publishing group corresponds to the minimum humidity (figure 1a). this indicates that the next stage, stage iii, is a transition from hard coals to anthracites. according to the classification of coal quality by genetic and technological characteristics [18] hard coals, by the upper value 𝑅𝑜, are classified if they are less than 1.6%. the lower limit for anthracites is the value 𝑅𝑜, equal to 1.4%. the absence of a specific boundary between hard coals and anthracites by the criterion 𝑅𝑜, confirms the presence of a transitional stage iii between them. the range of change in the indicator 𝑅𝑜, by the factor of the ratio of average values of the main components for the transitional stage, was within 1.43 ÷ 2.17% (table 1). according to the coal chemical map [19] by the brittleness criterion (output of dust class 1 ÷ 0 mm, cm3), coals of the l and sa grades are classified as transitional from hard coals to anthracites. these grades correspond to values 𝑅𝑜, in the range of 1.50-2.20% [20]. in the case under consideration, close values of the ranges of change in the vitrinite reflectance index for the transition stage were obtained both by the change in the ratio of the elemental content of the main components and by the consumer and physical-mechanical (brittleness, dust yield) properties of coals. this indicates a fairly reliable determination of the boundaries of the transition stage from hard coals to anthracites using different criteria characterizing metamorphic transformations. an increase in the difference between the growth of carbon content at this stage (∆сг= 4.92%) and a decrease in oxygen (∆ог= 1.77%) to 3.15% (table 1) indicates that carbon did not participate in the formation of fluids, including carbon dioxide. according to the graphs (figure 4) and the results of statistical processing (table 1), the main components of the combustible mass that participated in the formation of fluids were oxygen, hydrogen, and organic sulfur. at anthracite stages from iv to ix, the oxygen content in the combustible mass decreased slightly from 1.12% to 0.68%–0.80%. due to the small differences at these stages between the lower limits of the oxygen content (0.12%), its average value for all anthracite stages, which is 0.73%, was adopted for analysis (table 1). from a comparison of the significant increase in carbon content at the anthracite stages (∆сг= 4.48%) and the insignificant decrease in oxygen (∆ог= 0.39%) with its approximately constant and low average absolute value (0.73%), it follows that there is a practical absence of the possibility of the formation of common compounds containing carbon and oxygen. due to some slowdown in the growth of carbon content and the constancy of a small amount of oxygen content at anthracite stages iv-ix (figure 4), the formation of carbon compounds with other main components (hydrogen, sulfur, and nitrogen) is possible. the formation of such compounds is confirmed by studies [19]. stage x is characterized by a high carbon content (more than 97.23%). the sum of all other main components accounts for less than three percent. this indicates a decrease in the role of the elemental content of the main components in the formation of fluids that determine the hazardous properties of anthracite coal seams. for this reason, hazardous properties are determined, to a greater extent, by the amount of gas formed at previous stages of coal formation and preserved until the anthracite stages. the share of nitrogen and sulfur in the formation of fluids at all stages of metamorphic transformations can be assessed based on the graphs showing the dependence of their content on carbon in the combustible mass (figure 5). figure 5. dependence of nitrogen (a) and sulfur (b) content in the combustible part of the fuel on the carbon content for coal seams and anthracites. source: × experimental data [10]. changes in nitrogen and sulfur content are random for seams that have undergone the same metamorphic transformations according to the carbon content criterion. the nitrogen content changed insignificantly and was within the limit of two percent, regardless of the carbon content. when the content reaches сг more than 90% (at the anthracite stages), a certain tendency towards a decrease in nitrogen content is observed, and for some coal seams, its content is less than one percent (figure 5a). the nitrogen content in coals from different basins may differ significantly, but in most cases does not exceed three percent. there are anomalous cases of increased nitrogen content. for example, for the seam of 5  mine no. 3 "kochegarka" in the donetsk basin, the nitrogen content reached 4.2% [19] and for the seams of the dolinskaya suite in the karaganda basin, 8.6% [21]. such fluctuations in the nitrogen content are obviously associated to a large extent with differences in the composition of the original material and the conditions of its accumulation. regardless of the increase in the degree of metamorphic transformations (growth сг), the sulfur content for the coal seams of the donetsk basin fluctuates widely from 0.7 to 7.0% (figure 5b). asian review of environmental and earth sciences, 2025, 12(1): 6-13 12 © 2025 by the authors; licensee asian online journal publishing group unpredictable relationships between the carbon content and nitrogen and sulfur do not affect the accuracy of controlling the carbon (about one percent) of the sum of all other components of the combustible (organic) mass. for this reason, the equality: сг= 100 ∑ г о , нг, 𝑁г, 𝑆г, % (2) remains true for any mine seam, regardless of the degree of its metamorphic transformations and the different ratios between the main components. different ratios between the main components can significantly affect the manifestation of hazardous properties of coal seams. the high probability of such an effect is indicated by a significant change in the consumer qualities of coals with different oxygen contents. with an equal degree of metamorphic transformations of coal seams, coals with a lower oxygen content are distinguished by higher sintering, solubility in hydrocarbons, and heat of combustion. taking the yield of volatile substances as the only criterion for the degree of metamorphic transformations, it is impossible to establish different oxygen contents with the same reference values 𝑉𝑑𝑎𝑓. for this reason, the terms "reduction" and "oxidation" of fossil coals were introduced to characterize the consumer qualities [19]. differences in consumer properties were explained by genetic differences in coal types. it was proposed to distinguish four types of coal: type "a" slightly reduced coals; type "b" intermediate; type "c" reduced; type "bb" highly reduced. it was believed that the mineral part of coal is also genetically related to the composition and properties of the organic matter. according to the developed methodology [19], the type of hard coals by reduction is determined based on a comparison of the yield of volatile substances (𝑉𝑑𝑎𝑓) and the oxygen content in organic matter (oo) for two coal seams. additional indicators of reduction are considered to be the indicators of total sulfur (𝑆𝑡 𝑑) and the main oxides in the ash. the coal seams, which with approximately equal values of 𝑉𝑑𝑎𝑓, the oxygen content and the indicators of the content of total sulfur and main oxides in the ash (fe2o3, cao, mgo) also differed slightly from each other were considered to be of the same type. the different types mainly included coal seams with coals, the yield of volatile substances of which was approximately the same, but there were some differences in the oxygen content. to date, the permissible differences in the values of the index have not been determined 𝑉𝑑𝑎𝑓, at which two compared mine layers must be classified as belonging to the same degree of metamorphic transformations. the permissible differences in oxygen content, at which mine layers must be classified as of the same or different types, have also not been established. 4. conclusions preliminary analysis indicated that the reasons for the existing uncertainties in establishing the genetic types of coals may be due to provisions adopted during the development of the methodology that are insufficiently scientifically substantiated [19]. the main ones are: • the yield of volatile substances, taking into account the methods of determination, does not correspond to the classical (generally accepted) characterization of metamorphism as a change in the composition and properties of coals in the process of geological transformations of coal seams [22-24]. • metamorphism and thermal decomposition of coals are different stages of their transformation. the quantitative and qualitative composition of the volatile substances formed during thermal decomposition has no direct relation to the previously occurring metamorphic processes in natural conditions, in which part of the gaseous products had already been removed. thermal destruction is the result of a new (next) artificial stage of transformation of the original organic matter raised to the earth's surface [16]. • using only the yield of volatile substances as an indicator of metamorphism, it was not possible to confirm the fulfillment of hilt's rule for many mine seams [19]. • the organic mass consists of five main components. when establishing the reduction of coals and the uniformity of coal seams, only the oxygen content is taken into account [19], which is genetically related to the total individual content of carbon, hydrogen, nitrogen, and sulfur. in this case, organic sulfur is not considered a genetic component of the organic mass. • mineral impurities, roughly determined by the ash yield, are not indicators of metamorphic transformations of coals due to their preliminary enrichment during the preparation of analytical samples. to partially eliminate the influence of mineral impurities on the consumer qualities of fuel, coals are enriched until the ash yield is, as a rule, less than 10% [8]. it follows from the above analysis that the yield of volatile substances and the oxygen content in the organic mass do not unambiguously characterize either the types of coal seams by the supposed reduction of coals or the manifestation of hazardous properties during mining operations. in order to establish the true causes of changes in the properties of coal seams and their tendency to manifest hazardous phenomena, taking into account the genetic interdependence between the main components, it is necessary to consider individual relationships between them for each coal seam, and not limit ourselves to determining the content of only oxygen and total sulfur. references [1] guide to dust, guide to dust control in coal mines. moscow: nedra publishing house, 1979. [2] order of the federal service for environmental, technological and nuclear supervision of december 8, 2020 no. 506. on approval of the federal norms and rules in the field of industrial safety: "instructions for aerological safety of coal mines. moscow, russia: federal service for environmental, technological and nuclear supervision, 2020. [3] g. t. design, guide to design of coal mine ventilation. moscow: osnova, 1994. [4] guidelines for the prevention, guidelines for the prevention and extinguishing of endogenous fires in coal mines of ukraine: kd 12.01.402. donetsk: niigd, 2000. [5] instructions for forecasting, instructions for forecasting and preventing sudden methane breakthroughs from the soil of mine workings. russia: maknii, 1987, p. 29. [6] sou, sou. kiev: standard of the ministry of coal industry, 2009. asian review of environmental and earth sciences, 2025, 12(1): 6-13 13 © 2025 by the authors; licensee asian online journal publishing group [7] catalogue of dynamic, catalogue of dynamic faults of rocks in coal mines. russia: ussr coal industry institute, all-russian research institute of mining geomechanics and mine surveying, 1983. [8] i. v. avgushevich, e. i. sidoryuk, and t. m. bronovets, standard methods for testing coals. coal classifications. moscow: reklama master, 2018. [9] handbook of the quality, handbook of the quality of hard coals and anthracites of the donetsk and lviv-volyn basins. moscow: nedra, donetsk coal research institute, 1972. [10] handbook on the quality and beneficiation, handbook on the quality and beneficiation of coals and anthracites of the ukrainian ssr (donbass within the borders of the ukrainian ssr, lvov-volyn basin). characteristics of the quality of coals and anthracites of the ukrainian ssr. moscow: nedra, 1965. [11] v. a. uspensky, "experience of material balance of processes occurring during metamorphism of coal seams," oil and gas geology. theory and practice, vol. 1, pp. 1-10, 2006. [12] m. e. zheldakov and e. i. ivanova, handbook on the quality of anthracites of the soviet union. moscow: nedra, 1980. [13] catalogue of methane content, catalogue of methane content and outburst hazard of the main coal seams of the donetsk and lviv-volyn coal basins within the boundaries of operating mines. donetsk: mup ussr, cbnti, 1990. [14] g. a. babansky, "method for calculating methane content of highly metamorphosed anthracites and methods for constructing methane content maps of formations," in proceedings of maknii, occupational safety in coal mines, moscow, nedra, 1972, vol. 22, pp. 20-28. [15] catalogue of seams, catalogue of seams of the donetsk coal basin with characteristics of mining and geological factors and phenomena. moscow: institute of mining named after a.a. skochinsky (igd im. a.a. skochinsky), 1982. [16] n. i. antoshchenko and v. d. shepelevich, methane in coal seams from formation to release», monograph. alchevsk: donstu, 2006. [17] e. s. rudnev, v. a. galchenko, e. n. filatieva, and n. i. antoshchenko, "on the methodology for selecting indicators for predicting the hazardous properties of coal seams," technical engineering zhytomyr polytechnic state university, vol. 2, no. 88, pp. 148-167, 2021. [18] gost 25543-2013, interstate standard. brown coals, hard coals and anthracites. classification by genetic and technological parameters. moscow, standartinform: official publication, 2014. [19] geological and coal-chemical, geological and coal-chemical map of the donets basin. moscow, ugletekhizdat: donetsk coal research institute (donugi), 1954. [20] e. s. rudnev, v. a. galchenko, e. n. filatieva, and n. i. antoshchenko, "on the development of a general methodology for predicting the hazardous properties of coal seams," news of the donetsk mining institute, vol. 2, no. 49, pp. 135-148, 2021. [21] y. m. chernousov, geology of coal deposits. moscow: higher school, 1977. [22] gost 17070-2014, interstate standard. coals. terms and definitions. moscow, standartinform: official publication, 2015. [23] e. a. kozlovsky, mining encyclopedia. moscow: soviet encyclopedia, 1987. [24] v. s. beletsky, mining encyclopedic dictionary. donetsk: eastern publishing house, 2001. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 38 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 38-47, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.38.47 © 2021 by the authors; licensee asian online journal publishing group tree diversity, biomass and carbon stock in quartz mined area of bilikal hillock, hunasaekatte, bhadravathi, karnataka, south india appaji nanda1 gunguramale l. janardhana2 ( corresponding author) 1biodiversity education and research lab, environmental study centre, no. 70/1, opposite university of agricultural and horticultural sciences, shivamogga, karnataka, india; department of post graduate studies and research in applied botany, bioscience complex, jnana sahyadri, kuvempu university, shankaraghatta, shivamogga, karnataka, india. email: nanda.biodiversity@gmail.com tel: 9845047804 2biodiversity education and research lab, environmental study centre, no. 70/1, opposite university of agricultural and horticultural sciences, shivamogga, karnataka, india abstract to learn about the abandoned mined area tree diversity, aboveground biomass and carbon stock a study was conducted in quartz mined bilikal hillock area which is geographically adjacent to umbalebylu 8 km to bhadra wildlife sanctuary and 10 km of kuvempu university. in the present study 0.14ha (350 m×4m) transect, we recorded 1527 individuals comprising 22 families among them papilionaceae with 6 genera and 7 species, combretaceae with 2 genera and 4 species followed by rubiaceae with 3 genera and 3 species and apocynaceae with 2 genera and 3 species. based on girth class assessment nearly 1564 individuals comprising 1-10 cm had 559 individuals, the basal area was more within the girth class of 40-50 cm. but aboveground biomass and carbon stock were highest within the girth class of 20-30 cm. varying with species structure and girth class were a disturbed forest patch, the species composition needs management and restoration to retain the biodiversity intact to provide a niche for other co-species. keywords: aboveground biomass, carbon stock, diversity, ecological indices, girth class, quartz hillock, mining, trees, restoration, karnataka. citation | appaji nanda; gunguramale l. janardhana (2021). tree diversity, biomass and carbon stock in quartz mined area of bilikal hillock, hunasaekatte, bhadravathi, karnataka, south india. asian review of environmental and earth sciences, 8(1): 38-47. history: received: 28 july 2021 revised: 30 august 2021 accepted: 16 september 2021 published: 11 october 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: authors thank ccf dharwad for his encouragement and they thank biodiversity education and research lab, environmental study centre, shivamogga for logistics, they’re thanks to manjunatha, r and premnath, s. k for field assistance. funding: authors thank karnataka forest department for funding this minor project work to explore the tree diversity of mined area. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 39 2. material and methods ..................................................................................................................................................................... 39 3. methodology ..................................................................................................................................................................................... 40 4. results ................................................................................................................................................................................................ 42 5. discussion .......................................................................................................................................................................................... 44 6. conclusion ......................................................................................................................................................................................... 45 references .............................................................................................................................................................................................. 45 mailto:nanda.biodiversity@gmail.com http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.doi.org/10.20448/journal.506.2021.81.38.47 https://orcid.org/0000-0003-1592-0937 asian review of environmental and earth sciences, 2021, 8(1): 38-47 39 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature the present study provides baseline data of tree species composition, biomass and carbon stock in the abandoned mined area, which seeks further empirical research to know variation in species composition, edaphic characters and phenology for future restoration of the mined area. 1. introduction biodiversity at all levels is important to the composition, structure, and functioning of ecosystems and it provides many of the ecological services underpinning the human economy. hence biodiversity conservation is a major concern for all organisms [1]. based on bell, et al. [2] the duration and quality of mining the degradation of landscapes and the impact of biological community within the geological scale varies [2]. tropical forest communities are the biologically most complex and diverse ecosystems. the diversity is not distributed uniformly but concentrated in certain patches. the species richness, a simple measure of diversity can vary from forest types, of southern india. the highest biological and genetic diversity exists in tropical forests [3]. covering only 7 % of the earth’s land surface these forests have more than half of the worlds’ species [4]. based on forest statistics and research studies indicate, 54 % are classified as dry deciduous, and 37 % as moist deciduous [5, 6]. dry forest biodiversity population, dynamics and conservation efforts are very rare [7] even though their ratio compares to other forest is very less and are more threatened ecosystems. to assess the structure of tropical forest diversity and dynamics permanent plots of varying sizes were monitored[8, 9]. there has been increasing interest even in documenting the long-term dynamics of tropical forests through the establishment of permanent plots. tropical forest inventories serve as basic information for the conservation and management tools [10]. miles, et al. [11] have shown the landmass in tropics, tropical dry forests represents 42% as they detain 110 gt (gigatonne) vegetation carbon compared to 134 gt carbon in tropical rainforests, foley [12]. a huge carbon pool in the forest ecosystem is a result of high rate of terrestrial carbon cycle and high productivity [13]. carbon storage in trees through the process of biogeochemical processes [14]. carbon store is a result of photosynthesis and respiration, are sources of atmospheric carbon the major disturbances by natural causes and by human activities leads to become atmospheric carbon in the process of carbon cycle it restores within carbon sinks during growth can be managed to sequester or restore significant quantities of carbon in nature [15]. the atmospheric co2 absorption is assimilated in plant tissue in the growth of the plant chavan and rasal [16]. brown [15] has described the guidelines for estimation of carbon by intergovernmental panel on climate change (ipcc) in different landscape like forest, agriculture and other land uses. the three ways in which atmospheric co2 can be balanced: carbon sequestration, carbon conservation and carbon substitution [17]. on a global scale mitigating carbon emission the accurate way to measure carbon in forest as well as other ecosystem is gaining attention globally [15, 18]. net source and emission of greenhouse gas resulting in changes in forest cover historically [19, 20]. brown, et al. [21] for the accurate estimation of above ground biomass (agb), allometric equations are important with a non destructive method by measuring the independent variables like diameter at breast height (dbh). forests are influenced by the large-scale occurrence of wildfire, fire control, over-harvesting, collection of non timber forest products, and conversion of land to agriculture and forest and mining. the present mined area is adjacent to bhadra wildlife sanctuary the tree flora indicates the similar composition of species as recorded by krishnamurthy, et al. [22]. the limited studies on flora, tree biomass and carbon stock estimation in mined forests of india are limited, hence the present study describes the quartz mined area in bhadravathi, shivamogga, karnataka state. the floristic diversity studies based on the impact of mining and the purpose of mining on forest structure and functioning is needed for the restoration which begins with assessment hence the present study was carried with the objectives 1. to know the tree diversity and species composition of the mined hillock forest patch? 2. to know aboveground biomass and carbon stock based on girth class structure. 3. to find out the strategies in restoration of mined area. 2. material and methods 2.1. origin of the problem quartzite, usually metamorphic rock composed of firmly cemented quartz grains. quartzites occur in various metamorphic rocks in the form of solid sheet-like bodies extending for great distances. quartzites in which the sio2 content reaches 98–99 per cent are used for manufacturing dinas, refractories, for obtaining metallic silicon and its alloys, and as a flux in metallurgy. initially, mining activity began (the exact date is unavailable pertaining to the residents interaction it is 1970-1985) a lease granted to vishveshwaraiah iron and steel limited (visl), bhadravathi, karnataka. the present mined area lay close to the dry deciduous forest of the bhadra wildlife sanctuary and social forest (eucalyptus and acacia plantation) of mysore paper mills, paper town, bhadravathi. at present no mining activity (information from the residents of the surrounding two village area). 2.2. study area the study was conducted during (2013-2015) in and around bilikal mined area where the forest is partially disturbed without excavation. which is geographically adjacent to umbalebylu forest patch 8 km and 10 km of kuvempu university campus 13º 47' 425'' n lat, 75º 37' 394'' e long, the altitude is above 2229 feet msl (figure 1). champion and seth [23]classification characterize these forests as southern dry mixed deciduous forests. this site receives an annual rainfall of about 100-542 mm annually spread from may to december a winter period from november-january and a dry period from february-april with a minimum and maximum temperature varying from (15.3º-30.3º; 19.3º-36.6º) during the study period. the characteristic tree species of this site are terminalia paniculata, anogeissus latifolia, tectona grandis, and cassia fistula etc. asian review of environmental and earth sciences, 2021, 8(1): 38-47 40 © 2021 by the authors; licensee asian online journal publishing group figure-1. study area of quartz mined bilikal hillock bhadravathi, karnataka. india. 3. methodology to prepare a database of plant species for the bilikal mined area. all trees were randomly recorded within the respective transects of 350 m  4 m, (0.1ha). species were photographed and maintained as digital herbaria, in the environmental study centre. the tree species were confirmed to the taxonomic level by referring to the various regional floras [24-27] of karnataka, south india. 3.1. statistical analysis different ecological indices were performed to know the tree diversity as follows dominance, abundance, frequency and diversity the dominant species in a community are those assumed to be most important ecologically. they may be most numerous or of especially large size or high frequency of occurrence. quantitative dominance may not automatically be translated into ecological superiority, but provides a useful way of classifying communities. for plant communities measuring dominance usually entails determining three attributes of the species in the community: density (number of stems or individuals per unit area) which is a measure of the numerical dominance relative to other species: frequency (how many samples contain individuals of a given species), which measures the commonness of the species and coverage (basal area) which is a measure of the amount of space occupied by individuals of a given species. transect and plot data obtained were summarized according to the standard protocols.density, frequency and basal area (as r2) along with the abundance and their relative measures for each species have been calculated as follows, magurran [28]. density (d) = total no. of individuals / total no. of quadrats studied. abundance (ab) = total no. of individuals / no. of quadrats of occurrence. frequency (f) = no. of quadrants of species occurrence / total no. of quadrats studied. 3.2. measuring species diversity there are a number of ways to measure diversity. the differences among them are not particularly profound. most take into account species richness (the total number of species in the community). however, there is another asian review of environmental and earth sciences, 2021, 8(1): 38-47 41 © 2021 by the authors; licensee asian online journal publishing group aspect of species diversity that is frequently not accounted for by diversity indices, the evenness of distribution of individuals among species (also called equitability). 3.3. alpha diversity species richness alpha diversity is measured within the community. scale is specified and species richness is expressed as the number of species in a given standard sample (like the number of tree species per one-hectare sample). the simplest measure of species diversity is through the use of a species richness index, which is the number of species in the community regardless of dominance margalef’s species richness index was used to assess the species richness in the present study. margalef’s species richness index d = (s-1) ln n where s= number of species, n= total number of individuals species richness is the easiest to understand the component of diversity, but the problem is that the actual number of species usually unknown. species richness must be estimated by sampling the community. this, in turn, is affected by sample size and taxonomic error. the larger the sample the larger the species richness will be. we might estimate species richness by looking at the rate of increase with increasing sample size but we are assuming that the rate of increase will be constant. this may be untrue if our samples are large enough. 3.4. equitability or evenness if we are using samples, the results are then affected by differences in the numbers of individuals per sample. in this case, the role of dominance versus equitability or evenness becomes a factor. in the present study, pielou’s equitability index was calculated for knowing the evenness. pielou’s equitability index e = h1 /ln s where s= number of species n= total number of individuals, h1= shannon-wiener diversity index later ecologists introduced a second component, the evenness component into species diversity considerations. the richness and evenness components are combined into a single value, the heterogeneity index. the best known of these are the shannon-weiner and simpson diversity indices which are calculated as follows. shannon-weiner diversity index h1 = ∑pi ln pi simpson’sdiversity index d = (ni (ni-1) / (n (n-1) where ‘ith’ species = one of all the enumerated species pi = the proportion of the ‘i’th species = (ni /n) ni = number of individuals of the ‘i’th species n = total number of individuals. species aggregation concentrations were studied using simpson’s concentration dominance index. simpson’s concentration dominance index cd = e (ni /n) 2 where ni = density of the ‘i’ th species, n = total number of individuals. tree total biomass and carbon stock of the different tree species based on varying girth classes we calculated using allometric equations developed by brown, et al. [21]; takimoto, et al. [29]; khan [30]; sundarapandian, et al. [31]. pearson’s correlation was performed with different parameters to know the significance of the available data, zar [32]. table-1. tree species composition based on mined forest structure. total families 22 dominant family papilionaceae total genera 35 dominant genera terminalia spp. total species 42 dominant species anogeissus latifoliawall. dominant canopy tree anogeissus latifoliawall. dominant understorey tree helicteres isoral. total individuals 1527 64 dominant individual anogeissus latifoliawall. figure-2. proportion of families in the bilikal quartz mined area bhadravathi, karnataka. asian review of environmental and earth sciences, 2021, 8(1): 38-47 42 © 2021 by the authors; licensee asian online journal publishing group 4. results the present study recorded a total of 1527 trees belonging to 42 species, 35 genera and 22 families during the study table 1. based on the diversity of distribution papilionaceae with 6 genera and 7 species, combretaceae with 2 genera and 4 species followed by rubiaceae with 3 genera and 3 species and apocynaceae with 2 genera and 3 species figure 2. canopy / top storey of the bilikal composed of terminalia paniculata, terminalia tomentosa, pterocarpus marsupium and middle storey by tectona grandis, dalbergia latifolia and lannea coromandelica, while in the under/lower storey randia dumetorum, wrighitia tomentosa, holarrhena antidysentrica and helicteres isora were dominant. table 2. table-2. tree species of bilikal mined area of hunasaekatte, bhadravathi, karnataka, india. no. species family lifeform* individuals density abundance frequency 1 acacia concina (willd.) dc. mimosae wl 12 1.71 4 0.4 2 adina cordifolia (roxb).ridsd. rubiaceae c 14 2 4.6 0.4 3 aegle marmelos corr. rutaceae us 4 0.57 4 0.1 4 albiziz lebbeck benth. mimosae c 2 0.28 2 0.1 5 anogeissus latifolia wall. combretaceae c 269 38.42 44.8 0.8 6 bauhinia malabarica roxb. caesalpiniaceae us 2 0.28 2 0.1 7 bombax malabaricum dc. bombaceae c 4 0.57 4 0.1 8 butea monosperma (lam.) taub. papilionaceae us 10 1.42 3.3 0.4 9 careya arborea roxb. lecythidaceae us 15 2.14 2.5 0.8 10 cassia fistula l. caesalpiniaceae us 1 0.14 1 0.1 11 dalbergia latifolia roxb. papilionaceae c 33 4.71 11 0.4 12 dalbergia lanceolaria roxb. papilionaceae c 1 0.14 0.3 0.4 13 dilenya pentagyna roxb. dilleniaceae c 11 1.57 1.8 0.4 14 diospyrous melanoxylon roxb. ebenaceae us 49 7 8.1 0.8 15 embilica officinalis gaertn. euphorbiaceae us 4 0.57 4 0.1 16 erythrina indica lam. papilionaceae us 12 1.71 6 0.2 17 ficus bengalensis l. moraceae c 2 0.28 2 0.1 18 helicteres isora l. sterculiaceae us 142 20.28 28.4 0.7 19 holarrhena antidysentrica wall. apocynaceae us 116 16.57 19.3 0.8 20 lagerstroemia lanceolata wall. lythraceae c 2 0.28 2 0.1 21 lagerstromia parviflora roxb. lythraceae c 30 4.28 15 0.2 22 lannea coromandelica (houtt.) merr anacardiaceae c 21 3 7 0.4 23 mallotus phillippensis m.arg. euphorbiaceae us 18 2.57 18 0.1 24 mitragyna parviflora korth. rubiaceae c 2 0.285 2 0.1 25 polyolthia cinnaroides hk.f.andt. annonaceae us 8 1.14 2.6 0.4 26 pongamia pinnata l. papilionaceae us 2 0.28 2.6 0.1 27 pterosperum diversifolium blume papilionaceae us 15 2.14 15 0.1 28 pterocarpus marsupium roxb. papilionaceae c 14 2 14 0.1 29 radermachera xylocarpa bignoniaceae us 12 1.71 12 0.1 30 randia dumetorum (thunb.) tirven. rubiaceae us 112 16 28 0.5 31 schleichera oleosa (lour.) oken sapindaceae c 2 0.28 2 0.1 32 scolopia crenata clos. flacourtiaceae us 1 0.14 1 0.1 33 semicarpus anacardium l.f. anacardiaceae c 15 2.14 7.5 0.2 34 tectona grandis l.f. verbenaceae c 251 35.85 62.7 0.1 35 terminalia paniculata roth. combretaceae c 90 12.85 22.5 0.5 36 terminalia bellirica (gaertn.) roxb. combretaceae c 7 1 7 0.1 37 terminalia chebula retz. combretaceae c 1 0.14 0.2 0.1 38 terminalia tomentosa w. and a. combretaceae c 106 15.14 53 0.5 39 wrighitia tomentosa r.and s. apocynaceae us 87 12.42 87 0.2 40 wrightia tinctoria r.br. apocynaceae us 1 0.142 0.5 0.1 41 ziziphus rugosa lam. rhamnaceae wl 25 3.57 12.5 0.2 42 ziziphus oenoplia mill. rhamnaceae us 2 0.28 0.6 0.4 note: *life-form wl – woody liana, c – canopy tree, us – understorey tree. a dominant among the tree composition is anogeissus latifolia, (combretaceae ) with 269 individuals, density 38.42, abundance 44.8 and frequency 0.85, tectona grandis, (verbenaceae) with 251 individuals, density 35.85, abundance 62.75 and frequency 0.14, terminalia tomentosa (combretaceae) with 106 individuals, density 15.14, abundance 53 and frequency 0.5. table 2 tree diversity parameters are summarized in (table 3). diversity indices indicate that a moderate diversity in the human-disturbed area. based on transect the girth class, biomass and carbon stock was assessed for 1564 individuals. the number of individuals was highest within a girth class of 1-10 cm, followed by 20-30 cm, whereas basal area was highest asian review of environmental and earth sciences, 2021, 8(1): 38-47 43 © 2021 by the authors; licensee asian online journal publishing group within the girth class of 40-50 cm and total carbon stock is 0.776 t/ha, and for the present study of (0.14ha) it is 0.108 t/ha. table 4 and table 5. table3. ecological indices for tree species in bilikal mined area of bhadravathi, karnataka. parameters values taxa_s 42 individuals 1527 dominance_d 0.09 shannon_h 2.77 simpson_1-d 0.90 evenness_e^h/s 0.38 menhinick 1.07 margalef 5.59 equitability_j 0.74 fisher_alpha 7.98 berger-parker 0.17 table-4. different girth class, basal area, biomass and carbon stock for tree species in bilikal mined area of bhadravathi, karnataka. sl. no girth class no of individuals no. of species dbh (cm) basal area biomass carbon stock (t/ha) carbon stock (t/0.14ha) 1 1 – 10 559 32 1630.09 4118.05 212.84 106.42 14.89 2 10 -20 305 30 1583.24 6616.9 209.35 104.67 14.65 3 20-30 312 29 2482.81 15711.25 335.88 167.90 23.05 4 30-40 186 29 2061.24 18057.55 285.52 142.76 19.98 5 40-50 119 26 1706.36 19288.30 241.64 120.82 16.91 6 50-60 43 15 742.77 10102.14 107.06 53.53 7.49 7 60-70 17 10 345.04 5510.13 50.56 25.28 3.53 8 70-80 10 9 235.86 4372.70 35.12 17.56 2.45 9 80-100 5 4 138.14 3013.59 20.95 10.47 1.46 10 100-150 7 7 263.56 7842.04 41.50 20.75 2.9 11 >200 1 1 70.02 3851.54 11.97 5.98 0.83 table-5. a total assessment of different parameters for tree species in bilikal mined area of bhadravathi, karnataka. parameters total values ton/ha 0.14ha (350 x 4 mt) dbh 11259.19 11.25919 1.57628 basal area 98484.16 98.48416 13.7877 biomass 1552.36 1.55236 0.21733 carbon stock 776.181 0.77618 0.10866 species composition and basal area indicate the present forest patch has more juvenile individuals compare to mature figure 3 hence the restoration have greater importance in nurturing the forest ecosystem. the girth class with diameter indicates the (20-50 cm) girth class has a maximum number of basal area and carbon stock. figure 4. based on dbh (cm) and basal area (r = 0.53, p<0.05), basal area and biomass (r= 0.57, p<0.05), had a positive significance (figure 5a, b). whereas biomass and carbon stock (r=1.0, p<0.01) and dbh and carbon stock (r=0.98, p<0.01) had a strong positive significance figure5 c, d. figure-3. number of individual, species and girth class wise in the study area. asian review of environmental and earth sciences, 2021, 8(1): 38-47 44 © 2021 by the authors; licensee asian online journal publishing group figure-4. biomass and carbon stock among different girth class in the study area. figure-5. relationship between (a). diameter and basal area, (b) basal area and biomass. (c) biomass and carbon stock, (d) diameter and carbon stock, in a quartz mined hillock area, karnataka. 5. discussion the present tree species diversity is related to the quality and quantity of disturbance and the species composition structure. wattenberg and breckle [33] report the biodiversity of any forest is a measure of its species richness. the higher density of the small trees in the forest is likely to be related to the open canopy and low density of the larger trees [34]. in the present study highlights the species diversity based on the level of disturbance. but a higher level of disturbance gradually leads to the poorer stability of the forest [9]. this is supported by the present study that higher numbers of competent species like (randia dumetorum and holarrhena antidysentrica) than the tolerant species like (adina cordifolia, aegle marmelos, terminalia bellirica, mitragyna parviflora and embilica officinalis). thus the present study is concluded that stability and diversity are complementary and two central themes for the proper functioning of any ecosystem. the sample size selected in the study area and species composition varies within and between different forest types of the earlier studies. 1527 individual trees in 0.14 ha of the present study are much higher compared to other earlier studies. long term monitoring studies in different forest types show with 1766 trees in 2 ha permanent plot of bhadra wildlife sanctuary, karnataka [35] 540 tree/ha (≥ 1cm dbh) in the dry forests of mudumalai, tamilnadu, [36]. in kalakkadmundanthurai tiger reserve, 726 trees/ha [37]. in dry forests in vindhya hill ranges and 446 trees/ha of tropical evergreen forests of varagalairayyappan and parthasarathy [10]. murali, et al. [38] study from savanadurga state forests of karnataka with 30 quadrats of (25 m × 25 m) recorded 133 species. asian review of environmental and earth sciences, 2021, 8(1): 38-47 45 © 2021 by the authors; licensee asian online journal publishing group condit, et al. [39] lower girth class was more in the present study (i.e 43 % 794 stems), it may be due to the mortality of big trees that led to the creation of canopy gaps which helps to penetrate more solar light by supporting the level of recruitment of understory species and establish faster. gordon and newton [40] to minimize biodiversity loss by tropical deforestation and taking the biodiversity inventory as a tool for guiding conservation planning at a local scale by the international community especially in tropical countries where technical capacity is often limited. as this mined hillock area lies nearer to the natural dry forest of bhadra wildlife sanctuary, the species richness and its diversity may be a chance by the dispersal mechanism of accompanying bird, and animal species. (personal observation). different parameters of ecological indices are in support with other tropical forest diversity studies (krishnamurthy, et al. [35] and murali, et al. [38]. but long term monitoring with diversity and dynamics observations are required in the present changing climate to understand species composition for the restoration of the mined area in the present study area and elsewhere. nearly 37 individuals fall under the category of unidentified /partially disturbed species without access to leaf, flower and fruit for the identification and confirmation of taxonomic group but living, hence those individuals assessed for carbon stock. daubenmire [41] research reveals that trees in the dry (deciduous) forest face loss of water resulting in a reduction in stem diameter. in the present study number individual, species composition varies with girth class; the basal area is highest within the girth class of 40-50 cm with a 119 individual, least with a girth class of 80-100 cm with 5 individuals. whereas the highest biomass 335.88 t/ha with 312 individuals. (figure 3).may be reduction in loss of water in the stem biomass. haripriya [42] biomass per hectare based on aboveground large scale inventories analysis rages from 14 to 210 mg/ha. according to chaturvedi, et al. [43] carbon density ranging from 15.6 to 151 t-c ha-1 in tropical dry forests of india, but at the global level the aboveground carbon density in dry forest it varies between 14 and 123 t-c ha-1, as noticed by murphy and lugo [44] based on the girth class it varies from 10 -200 cm carbon stock for 0.14 ha 0.83 to 23.05 tons. carbon stock is not dependent on biomass but independent on the basal area. (table 1).newbery and gartlan [45] changes in species diameter used as an indicator of population changing structure. the present study is in agreement as the mined area indicates the different girth class from 10 to > 200 cm the anthropogenic perturbation changes the forest structure its basal area and biomass varies with a number of active individuals (table 2). a different diameter class indicates the resource utilization by the growing forest, krebs [46]. the different age class in the present study shows the partition of resources like water, soil, sunlight, canopy and changing strata due to mining, girth class of 20-30 cm with a 312individual had more carbon stock with less biomass than 40-50 cm girth class had less carbon holding capacity this directly attributes the significance species composition and abiotic factors. (figure 4). the high carbon storage is recorded especially through raising plantations in indian forests (e.g. [47-50]). but the natural species composition and structure cannot be matched or compared with the manmade plantation hence we need to know species composition, structure, biomass and carbon stock capacity in the small patches of the forest even though disturbed by humans as it helps in rehabilitation based on species growth pattern and geographical features. the land use and carbon sequestration model (lucs) model and estimated that under a regular plantation forestry scenario in india, 7 pg of carbon would be sequestered between 2000 and 2050 by suruchi and roma [47]. in the estimation of long term, large permanent plots the small forest patches contribution of carbon stock is unnoticed as in the present study indicates the contribution of different girth class carbon holding capacity. (table 4). lal and singh [51] found that the difference in biomass productivity of natural forest cover (1.1 mg ha−1yr−1) and plantations (3.2 mg ha−1yr−1), the carbon sequestration potential was in the range of 1.1 and 2.7 pg c, respectively, by the years 2020 and 2045 (cumulative carbon uptake from the atmosphere). the major deterrent characters of carbon stock are tree species, climate, age, size class distribution etc [52, 53]. small patches of forest, as well as disturbed and partially mined forest ecosystem, shows their real vegetation if assessed and documented helps in having a basic database to understand the future consequences. pearson correlation analysis indicates a positive relationship with a diameter at breast height with the basal area and with basal area and biomass (figures 5a and b), .the similar observation is noticed from, sundarapandian, et al. [31]. whereas biomass and carbon stock had a strong positive relationship as well as diameter at breast height with carbon stock shows a strong positive relationship similar observation has been recorded in other tropical forests [54, 55]. the carbon sequestration capacity is high in plantation than in natural forests is due to better silvicultural management practices [50]. if the forest ecosystems are better managed based on disturbance gradient probably we can achieve better species composition, biomass and carbon sequestration with an innovative restoration practice in the coming future. 6. conclusion generally, when land is surface-mined, the entire forest including shrub layer, tree canopy, rootstocks, seed pools, animals, and microorganisms is removed. after mining, the forest takes enough time to restore to its original function and structure through a series of a process called forest succession. on exploration of floristic diversity to know the abandoned mined (affected) area. we found some species are thriving well; the abandoned mined area need eco protection from tree logging, domestic animal grazing. there is an urgent need to monitor, the diversity, distribution of native, exotic, herbs, shrubs, grasses, creepers, lianas and faunal diversity of birds and animals of the area with phenological observation [56] to know how they are coping with disturbances will help in forest restoration success in india and elsewhere. references [1] b. czech, "technological progress and biodiversity conservation: a dollar spent, a dollar burned," conservation biology, vol. 17, pp. 1455-1457, 2003.available at: https://doi.org/10.1046/j.1523-1739.2003.02370.x. [2] f. bell, s. bullock, t. hälbich, and p. lindsay, "environmental impacts associated with an abandoned mine in the witbank coalfield, south africa," international journal of coal geology, vol. 45, pp. 195-216, 2001.available at: https://doi.org/10.1016/s0166-5162(00)00033-1. asian review of environmental and earth sciences, 2021, 8(1): 38-47 46 © 2021 by the authors; licensee asian online journal publishing group [3] s. p. hubbell and r. b. foster, diversity of canopy trees in a neotropical forest and implications for conservation. in: s.l. sutton, t.c. whitmore and a.c. chadwick (eds.), tropical rain forest: ecology and management. oxford: blackwell scientific publications, 1983. [4] r. m. may and m. p. stumpf, "species-area relations in tropical forests," science, vol. 290, pp. 2084-2086, 2000.available at: https://doi.org/10.1126/science.290.5499.2084. [5] o. kaul and d. sharma, "forest types statistics," indian forester, vol. 97, pp. 435-436, 1971. [6] k. p. singh and c. p. kushwaha, "emerging paradigms of tree phenology in dry tropics," current science, vol. 89, pp. 964-975, 2005. [7] s. h. bullock, h. a. mooney, and e. medina, "seasonally dry deciduous forests," ed: cambridge university press, 1995, pp. 1-450. [8] n. parthasarthy, "changes in forest composition and structure in three sites of tropical evergreen forest around sengaltheri, western ghats," current science, vol. 80, pp. 389-393, 2001. [9] r. sagar, a. raghubanshi, and j. singh, "tree species composition, dispersion and diversity along a disturbance gradient in a dry tropical forest region of india," forest ecology and management, vol. 186, pp. 61-71, 2003.available at: https://doi.org/10.1016/s0378-1127(03)00235-4. [10] n. ayyappan and n. parthasarathy, "biodiversity inventory of trees in a large-scale permanent plot of tropical evergreen forest at varagalaiar, anamalais, western ghats, india," biodiversity & conservation, vol. 8, pp. 1533-1554, 1999. [11] l. miles, a. c. newton, r. s. defries, c. ravilious, i. may, s. blyth, v. kapos, and j. e. gordon, "a global overview of the conservation status of tropical dry forests," journal of biogeography, vol. 33, pp. 491-505, 2006. [12] j. a. foley, "an equilibrium model of the terrestrial carbon budget," tellus b: chemical and physical meteorology, vol. 47, pp. 310319, 1995.available at: https://doi.org/10.1034/j.1600-0889.47.issue3.3.x. [13] w. h. schlesinger, biogeochemistry: an analysis of global change, 2nd ed. new york: academic press, 1977. [14] b. chavan and g. rasal, "comparative status of carbon dioxide sequestration in albizia lebbek and delonix regia," universal journal of environmental research and technology, vol. 2, pp. 85-92, 2012. [15] s. brown, "estimating biomass and biomass change of tropical forests: a primer," ed italy: food & agriculture organization, 1997, pp. 1-134. [16] b. chavan and g. rasal, "sequestered standing carbon stock in selective tree species grown in university campus at aurangabad, maharashtra, india," international journal of engineering science and technology, vol. 2, pp. 3003-3007, 2010. [17] f. montagnini and p. k. r. nair, "carbon sequestration: an underexploited environmental benefit of agroforestry systems," agroforestry systems, vol. 61, pp. 281-295, 2004.available at: https://doi.org/10.1023/b:agfo.0000029005.92691.79. [18] p. kauppi and r. sedjo, "technical and economic potential of options to enhance, maintain and manage biological carbon reservoirs and geo-engineering. in: metz, b., davidson, o., swart, r., pan, j. (eds.), climate change 2001: mitigation," contribution of working group iii to the third assessment report of the ipcc. cambridge university press, cambridge, uk2001. [19] r. houghton, "the annual net flux of carbon to the atmosphere from changes in land use 1850–1990," tellus b, vol. 51, pp. 298313, 1999.available at: https://doi.org/10.3402/tellusb.v51i2.16288. [20] r. a. houghton, j. l. hackler, and r. m. cushman, "carbon flux to the atmosphere from land-use changes: 1850 to 1990: carbon dioxide information analysis center and world data centrea for atomospheric trace gases," catalog of databases and reports, oak ridge national laboratory. national technical information service, u.s. department of commerce, 5285 port royal rd., springfield, va 22161, pp. 1-2082001. [21] s. brown, a. j. gillespie, and a. e. lugo, "biomass estimation methods for tropical forests with applications to forest inventory data," forest science, vol. 35, pp. 881-902, 1989. [22] y. krishnamurthy, h. prakasha, and a. nanda, "floristic diversity of bhadra wildlife sanctuary in the central western ghats region, karnataka," indian forester, vol. 135, pp. 1397-1406, 2009. [23] h. g. champion and s. k. seth, a revised survey of the forest types of india. delhi: govt. of india press, 1968. [24] j. s. gamble and c. e. c. fischer, "flora of the presidency of madras." vol. i-iii, ed hart street, w.c: adlard and son, ltd, 1998, p. 680. [25] c. j. saldanha, flora of karnataka vol. 1-6. new delhi: oxford and ibh publishing co. pvt. ltd, 1996. [26] s. n. yoganarasimhan, k. subramanyam, and b. a. razi, flora of chikkamagalur district, karnataka, india. deharadun: international book distributors, 1982. [27] s. n. ramaswamy, m. r. rao, and d. a. govindappa, flora of shimoga district. karnataka, manasagangotri, mysore: prasaranga university of mysore, 2001. [28] a. e. magurran, ecological diversity and its measurement. london: croom helm limited, 1998. [29] a. takimoto, p. r. nair, and v. d. nair, "carbon stock and sequestration potential of traditional and improved agroforestry systems in the west african sahel," agriculture, ecosystems & environment, vol. 125, pp. 159-166, 2008.available at: https://doi.org/10.1016/j.agee.2007.12.010. [30] a. khan, "assessment of carbon storage in pondicherry mangroves, pondicherry, india," acta biologica malaysiana, vol. 2, pp. 9599, 2013. [31] s. sundarapandian, s. amritha, l. gowsalya, p. kayathri, m. thamizharasi, j. a. dar, k. srinivas, d. gandhi, and k. subashree, "biomass and carbon stock assessments of woody vegetation in pondicherry university campus, puducherry," international journal of environmental biology, vol. 4, pp. 87-99, 2014. [32] j. h. zar, biostatistical analysis. new jersey. usa: prentice-hall, 2007. [33] i. wattenberg and s. breckle, "tree species diversity of a pre montane rain forest in the cordillera de tilaren, costa rica," biotropica, vol. 1, pp. 21-30, 1995. [34] n. manokaran and h. v. la frankie, "stand structure of pasoh forest reserve, a low land rain forest in peninsular malaysia," journal of tropical forest science, vol. 3, pp. 14-24, 1990. [35] y. krishnamurthy, h. prakasha, a. nanda, m. krishnappa, h. dattaraja, and h. suresh, "vegetation structure and floristic composition of a tropical dry deciduous forest in bhadra wildlife sanctuary, karnataka, india," tropical ecology, vol. 51, pp. 235246, 2010. [36] r. sukumar, h. s. dattaraja, h. s. suresh, r. radhakrishna, s. n. vasudeva, and n. v. joshi, "long-term monitoring of vegetation in a tropical deciduous forest in mudumali, southern india," current science, vol. 84, pp. 608-610, 1992. [37] t. ganesh, r. ganesan, m. s. devy, p. davidar, and k. bawa, "assessment of plant biodiversity at a mid-elevation evergreen forest of kalakad—mundanthurai tiger reserve, western ghats, india," current science, vol. 71, pp. 5-10, 1996. [38] k. s. murali, a. kavitha, and r. p. harish, "spatial patterns of trees and shrub species diversity in savanadurga state forest, karnataka," current science, vol. 62, pp. 808-813, 2003. [39] r. condit, s. p. hubbell, and r. b. foster, "short-term dynamics of a neotropical forest," bioscience, vol. 42, pp. 822–828, 1992.available at: https://doi.org/10.2307/1312081. [40] j. e. gordon and a. c. newton, "efficient floristic inventory for the assessment of tropical tree diversity: a comparative test of four alternative approaches," forest ecology and management, vol. 237, pp. 564-573, 2006.available at: https://doi.org/10.1016/j.foreco.2006.10.002. [41] r. daubenmire, "phenology and other characteristics of tropical semi-deciduous forest in northwestern costa rica," journal of ecology, vol. 60, pp. 147-170, 1972.available at: https://doi.org/10.2307/2258048. [42] g. haripriya, "biomass carbon of truncated diameter classes in indian forests," forest ecology and management, vol. 168, pp. 1-13, 2002.available at: https://doi.org/10.1016/s0378-1127(01)00729-0. [43] r. chaturvedi, a. raghubanshi, and j. singh, "leaf attributes and tree growth in a tropical dry forest," journal of vegetation science, vol. 22, pp. 917-931, 2011.available at: https://doi.org/10.1111/j.1654-1103.2011.01299.x. [44] p. g. murphy and a. e. lugo, "ecology of tropical dry forest," annual review of ecology and systematics, vol. 17, pp. 67-88, 1986. [45] d. m. newbery and j. gartlan, "a structural analysis of rain forest at korup and douala–edea, cameroon," proceedings of the royal society of edinburgh, section b: biological sciences, vol. 104, pp. 177-224, 1996.available at: https://doi.org/10.1017/s0269727000006138. asian review of environmental and earth sciences, 2021, 8(1): 38-47 47 © 2021 by the authors; licensee asian online journal publishing group [46] c. j. krebs, ecological methodology. new york, usa: harper and row, 1989. [47] b. suruchi and s. roma, "carbon sequestration estimates for forestry options under different land-use scenarios in india," current science, vol. 83, pp. 1380-1386, 2002. [48] r. manhas, j. negi, r. kumar, and p. chauhan, "temporal assessment of growing stock, biomass and carbon stock of indian forests," climatic change, vol. 74, pp. 191-221, 2006.available at: https://doi.org/10.1007/s10584-005-9011-4. [49] n. hooda, m. gera, k. andrasko, j. sathaye, m. gupta, h. vasistha, m. chandran, and s. rassaily, "community and farm forestry climate mitigation projects: case studies from uttaranchal, india," mitigation and adaptation strategies for global change, vol. 12, pp. 1099-1130, 2007.available at: https://doi.org/10.1007/s11027-006-9066-1. [50] r. baishya, s. k. barik, and k. upadhaya, "distribution pattern of aboveground biomass in natural and plantation forests of humid tropics in northeast india," tropical ecology, vol. 50, pp. 295–304, 2009. [51] m. lal and r. singh, "carbon sequestration potential of indian forests," environmental monitoring and assessment, vol. 60, pp. 315327, 2000. [52] j. a. vucetich, d. d. reed, a. breymeyer, m. deg´orski, g. d. mroz, j. solon, e. roo-zielinska, and r. noble, "carbon pools and ecosystem properties along a latitudinal gradient in northern scots pine (pinussylvestris) forests," forest ecology and management, vol. 136, pp. 135–145, 2000.available at: https://doi.org/10.1016/s0378-1127(99)00288-1. [53] a. pussinen, t. karjalainen, r. mäkipää, l. valsta, and s. kellomäki, "forest carbon sequestration and harvests in scots pine stand under different climate and nitrogen deposition scenarios," forest ecology and management, vol. 158, pp. 103-115, 2002.available at: https://doi.org/10.1016/s0378-1127(00)00675-7. [54] s. mani and n. parthasarathy, "above-ground biomass estimation in ten tropical dry evergreen forest sites of peninsular india," biomass and bioenergy, vol. 31, pp. 284-290, 2007.available at: https://doi.org/10.1016/j.biombioe.2006.08.006. [55] k. murali, d. bhat, and n. ravindranath, "biomass estimation equations for tropical deciduous and evergreen forests," international journal of agricultural resources, governance and ecology, vol. 4, pp. 81-92, 2005.available at: https://doi.org/10.1504/ijarge.2005.006440. [56] h. s. suresh and a. nanda, "comparative phenologies of two tropical dry forests in southern india," journal of global ecology and environment, vol. 3, pp. 36-57, 2021. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 68 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 68-76, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.68.76 © 2021 by the authors; licensee asian online journal publishing group total petroleum hydrocarbons contamination of the surface water and sediments of orashi river, engenni, ahoada west, rivers state, nigeria edori, e. s1 edori, o. s2 bekee, d3 ( corresponding author) 1,2department of chemistry, ignatius ajuru university of education rumuolumeni, port harcourt, rivers state, nigeria. 2email: onisogen.edori@yahoo.com 3department of chemistry, rivers state university, port harcourt, rivers state, nigeria. abstract the level of contamination of orashi river by total petroleum hydrocarbons were investigated through the collection of surface water samples and sediment samples from four locations along the river. determination of the level of contamination was done with the use of gas chromatography-flame ionization detector after following laid down clean-up procedures. the results obtained showed that total petroleum hydrocarbons in the surface water were 10.913±2.2022mg/l, 7.645±2.683mg/l, 9.074±2.1654mg/l and 12.212±3.3034mg/l for stations 1, 2, 3 and 4 respectively with a mean value of 9.961±2.5885mg/l, while in the sediment samples concentration values recorded were 22.3925±5.2104mg/kg, 35.1071±9.9652mg/kg, 50.4431±15.9916mg/kg and 29.3869±8.0410mg/kg for stations 1, 2 3 and 4 respectively with a mean value of 34.3324±9.8021mg/kg. the partition coefficient calculations revealed that the sediment phase is more stable for total petroleum hydrocarbons as compared to the water phase. the analysis of the randomly collected samples revealed that total petroleum hydrocarbons have contaminated the river and therefore adequate steps should be taken to remedy the present condition of the orashi river in order to mitigate any probable rise in the quantity of total petroleum hydrocarbons in the river above allowable limit. keywords: contamination, gas chromatography-flame ionization detector, orashi river, sediments, surface water, total petroleum hydrocarbons. citation | edori, e. s; edori, o. s; bekee, d (2021). total petroleum hydrocarbons contamination of the surface water and sediments of orashi river, engenni, ahoada west, rivers state, nigeria. asian review of environmental and earth sciences, 8(1): 68-76. history: received: 6 october 2021 revised: 29 october 2021 accepted: 22 november 2021 published: 13 december 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 69 2. materials and methods ................................................................................................................................................................... 70 3. results and discussions .................................................................................................................................................................. 71 4. conclusion ......................................................................................................................................................................................... 74 references .............................................................................................................................................................................................. 74 mailto:onisogen.edori@yahoo.com http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.doi.org/10.20448/journal.506.2021.81.68.76 https://orcid.org/0000-0002-3613-8576 https://www.doi.org/10.20448/journal.506.2021.81.68.76 https://orcid.org/0000-0002-3613-8576 https://www.doi.org/10.20448/journal.506.2021.81.68.76 https://orcid.org/0000-0002-3613-8576 asian review of environmental and earth sciences, 2021, 8(1): 68-76 69 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes to existing literature by unveiling the concentrations of total petroleum hydrocarbons in water and sediment matrixes of the orashi river in engenni, rivers state. the study further confirmed that the sediment is a repository or sink of pollutants in aquatic medium by holding more of total petroleum hydrocarbon components than the surface water. 1. introduction the quality of water is very important in the life of aquatic organisms. the quality of water has been under great attack due to oil exploration and exploitation in the niger delta region of nigeria. poor water quality and pollution arose as a result of the rise in industrial and agricultural activities, population growth and urbanization [1]. organisms or certain species may be eliminated at certain level of pollution due to their inability to withstand stress [2]. water bodies need special attention to prevent and protect it from excessive devastation and degradation that resulted from industrial, agricultural and other forms of environmental deterioration [3, 4]. water as an essential aspect of human life is obtained from natural sources such as ground water (well and borehole), also known as geological water and water bodies such as lakes, streams, rivers, lagoons, seas and oceans (also known as surface water) [5-7]. even though water is very essential and of immense benefits, there is difficulty in its accessibility due to its high rate of degradation from contamination and pollution. as a result of anthropogenic activities, technological advancement, increased human population, industrialization, oil production activities, etc, a wide range of contaminants are introduced daily into the water bodies and the aquatic environment, which have contributed negatively to the poor water qualities of rivers of niger delta [8-10]. a major challenge in the area designated as niger delta in nigeria, is the issue of water quality. the contamination, degradation and pollution of water in this region is as a result of the increase in the production of petroleum hydrocarbons [11-13]. this has contributed greatly to the environment being degraded and polluted [14]. due to the activities of man, such as the drive for the use of crude oil-based products like diesel, petrol (gasoline), lube oil, asphalt, etc, the contamination of the water body has greatly increased. petroleum hydrocarbons find its way into the rivers through marine transportation, aerial depositions from gas flaring, runoffs from polluted land due to rain, dumping directly into the river, refinery effluents, industrial and municipal waste [15-17]. the increased activities of oil exploitation and exploration by multinationals, illegal refining of oil and bunkering, transportation and storage of petroleum products has caused unquantifiable pollution along the creeks, rivers, estuaries and other coastline in the niger delta area. this has led to the depletion of the sources of livelihood of the people of the region [18, 19]. despite the huge resources that petroleum hydrocarbons have contributed to the globe, its contamination due to the exploration and production operations has caused widespread environmental pollution, poor human health, socio-economic challenges and even conflicts among host communities and even nations [20]. the discharge of crude oil (petroleum hydrocarbons) has caused or contributed greatly to severe environmental pollution, bringing about environmental degradation and deterioration, loosing of cultural heritage and also creating socio-economic problems over the past years in the niger delta region of nigeria [21-24]. the contamination and deterioration of the river causes some serious consequences on the ecosystem, which result in adverse effect on the marine ecosystem by impacting on wild life, fishing, tourism, transportation and other associated businesses within that area [25, 26]. crude oil or petroleum hydrocarbons may find its way into the environment through oil spill, which may occur due to equipment failure, damage of pipeline through willful act, operational mistakes or errors, sabotage, corrosion of pipes and storage tanks [27, 28]. environmental reports have shown that high level of organic (including petroleum hydrocarbons) and inorganic chemicals have impacted on the environment, due to the activities of these industries. their effects have been adverse and have exceeded both international and national acceptable limits in different environments [2932]. the activities of petroleum industries have severe environmental impacts and consequences on the inhabitants or the particular environment where the activity took place. as a result of oil prospecting activities, there is great possibility of environmental degradation which may arise as a result of oil spill [33]. as a result of the toxic nature of crude oil and its products, there is widespread destruction of farmland in addition to other socio-economic consequences to the host communities of the trans national oil companies. when there is oil spill at sea due to illegal oil bunkering activities, pipeline explosion, the effect is as dangerous and drastic as on the land, posing a threat to the sea organisms [33-35]. aquatic organisms which survive through oxygen metabolism may die due to oil film blocking the oxygen being dissolved in the water. the process of oil spill also renders the water quality low and unfit for drinking, tourism, agriculture and other related activities [36, 37]. health deterioration of man and other organisms is also another effect of total hydrocarbon content. it poses serious health threat due to gases associated with it. total hydrocarbon content can affect the central nervous system, lungs and blood cells of man and animals. other effects are asphyxiation of water organisms, which comes as a result of oil coating the water surface. this may result in death of water organisms, causing impairment in growth and development of marine organisms, mutagenic and carcinogenic effects are produced in man. there is also the problem of marketability of marine fishes, crustaceans, molluscs and other sea animals due to objectionable flavour which reduces their acceptability. total petroleum hydrocarbons may also lead to death of both water flora (plants) and fauna (animals), [19, 38-40]. due to oil prospecting and exploitation activities, pollutants such as petroleum hydrocarbons which are toxic and persistent in the environment are always discharged [41]. there is also great absence of portable water due to these activities, which has resulted in the unfitness of most river water for consumption and thus a threat to aquatic life, which man depends on for food. this has led to the search for alternative sources of water for both domestic and industrial uses, which also are not altogether safe from hydrocarbons and other pollutants [42]. studies have shown that aquatic organism accumulate hydrocarbons in their tissues at varying degrees [43], which at very high concentrations can both be risk to them and their consumers. asian review of environmental and earth sciences, 2021, 8(1): 68-76 70 © 2021 by the authors; licensee asian online journal publishing group the research work determined the extent of contamination/pollution resulting from total petroleum hydrocarbons in surface water and sediments of the orashi river. the concentration of the total petroleum hydrocarbons was determined using chromatographic methods with the equipment model agilent 5890 gas chromatograph – flame ionization detector (gcfid). 2. materials and methods 2.1. study area and location the study area covers the orashi river in engenni, ahoada west local government area of rivers state, in the niger delta area of south south nigeria. the orashi river is a tributary of river niger and runs from imo state through ogba egbema ndoni local government area to engenni in ahoada west local government area of rivers state. the sample location points in the engenni axis of the orashi river were within the geographic positions 4o107.3’n, 6o30’6.6”e and 4o59’10.1”n, 6o27’2.5”e . the inhabitants of engenni are mainly fishermen and farmers. there are numbers of activities that take place within the engenni axis of the river which includes, oil exploration and production, illegal oil bunkering, transportation, etc. oil production facilities that belongs to multinational oil companies includes flow station, oil fields, gas plants, which has constantly led to the contamination of the river. the environmental impact and pollution due to oil exploitation and production over the years in this region have been a source of worry for the inhabitants. other activities that are predominant in the river apart from oil production includes fishing, sand mining recreational activities (such as swimming and canoeing). 2.2. collection of water sample water sample was collected from four different stations in orashi river using glass bottles. the glass bottles were previously washed with dichloromethare to ensure no contamination with the water sample. three different points were collected in each station at a depth of 40cm and mixed together to form a representative sample. preservation of the water sample was done by adding 2ml of 0.2m h2so4 to bring the ph to about 2. in other to prevent any harm or contamination, the bottles are covered with sterile pieces of aluminum foil, after which the bottles were tightly covered with plastic screw. the bottles were then kept in an ice packed cooler to keep it at 4oc then transported to the laboratory for sample pre-treatment and analysis [44]. 2.3. collection of sediment sample sediment samples were collected at the four different stations in orashi river from the top few centimeters deep. bulk representative samples were formed by mixing three points sediments together. the samples were collected using a hand held, van veen grab and transferred to glass bottles then transported to the laboratory. the collected sediment samples are treated as in the case of water samples. 2.4. water samples extraction for total petroleum hydrocarbon determination water samples were filtered and then subjected to extraction procedures through the use of separatory funnel. water samples of different volume were collected from different stations, and extracted into a two liters’ (2l) glass separatory funnel and filtered with a glass stopper 30ml dichloromethane as solvent for extraction. the separatory funnel was shaken for at least 5 minutes. this allows the organic layer to clearly separate itself from the aqueous layer. 5g of anhydrous sodium sulphate was mixed with the extract (lower layer) in order to remove water. the sample was then collected into a beaker with the aid of filter paper. the filtrate is allowed to evaporate at room temperature in a fume cupboard. the filtrate was allowed to be concentrated to 3ml. the process of extraction was repeated three times for each sample collected [45]. 2.5. extraction of sediment sample for total petroleum hydrocarbon determination an analytical weighing balance was used to weigh 10g of sediment sample and was transferred into an amber bottle. then 5g of anhydrous sodium sulphate (na2so4) was measured and put into the amber glass bottle that contains the sediment sample, and then the sediment sample is shaken vigorously for effective mixing of particles. the purpose of adding anhydrous sodium sulphate is to reduce moisture from the sediment sample. after through mixing of the sample, 30ml dichloromethane was added to the sediment sample as the extracting solvent. after the addition of dichloromethane, the amber bottle was then very tightly closed and then transferred to a mechanical shaker and was agitated at room temperature and the sample allowed to settle for 1hr interval. then using a 110mm filter paper the sediment sample was filtered into a clean beaker that has board, the filtrate of the sediment sample was allowed to concentrate to 1ml by evaporation [45]. 2.6. sample clean up column preparation was performed through the introduction of glass-wool into an already washed chromatographic column. then into an already clean beaker silica gel was introduced. addition slurry was made into chromatographic column. an anhydrous sodium sulphate was added into the column then the addition of pentane thereafter. in a previously cleaned beaker, the concentrated sample was mixed with cyclohexane and then introduced into the column already prepared. the sample was eluted with pentane and then collected into the beaker below the column. furthermore, the elution of sample was carried out by the introduction of more pentane, after which the column was then rinsed with dichloromethane. the sample was allowed to stand in a fume cupboard after elution at room temperature for evaporation to take place [45]. 2.7. sample separation and detection agilent 5890n gas chromatography-flame ionization detector (gc-fid) was used for the detection of total petroleum hydrocarbons in sediment and water samples at the different stations of the area under study [46]. 3ml of concentrated sample was injected into the gas chromatography vial for cleaning of syringe, the blank dichloromethane was injected into micro-syringe of gas chromatography. before the analysis of the sample, the asian review of environmental and earth sciences, 2021, 8(1): 68-76 71 © 2021 by the authors; licensee asian online journal publishing group cleaning of the syringe was done thrice. the micro-syringe was rinsed later with the sample after which the sample was then injected into the gas chromatography for the total separation of the different components of the sample. after separation of components in the sample, the amount of total petroleum hydrocarbon content resolved at a particular chromatogram was then measured in mg/kg for the sediment sample and ml/l for water sample. 2.8. partition coefficient total petroleum hydrocarbon bio availability in sediment of the rivers solely depends on its distribution between the sediment and the surface water. it lies on the level of total petroleum hydrocarbon in the sediment phase and surface water phase. the spread of the distribution is measured by partition coefficient. the partition coefficient is mathematically represented as this is done to ascertain which of the phases that total petroleum hydrocarbon prefers. 2.9. statistical analysis data obtained were subjected to one-way analysis of variance (anova) to test if there exist a significant difference between mean values obtained from the different station. where differences existed, duncan multiple range test (dmrt) was used to separate the means. 3. results and discussions the degree of contamination and pollution of the surface water and sediments by total petroleum hydrocarbons in the orashi river in sampled stations are shown in table 1 and 2. the extent to which the river was polluted was a factor of the amount of total petroleum hydrocarbons present per litre of water or per kilogram of sediment. the tables revealed the levels of the different fractional components of total petroleum hydrocarbons present in surface water and sediments of the various samples collected from the river. the mean concentrations of total petroleum hydrocarbons in the surface water and sediments of the river are discussed below. the level of contamination due to total petroleum hydrocarbons in the surface water of orashi river in the various stations are shown in table 1. the concentration/contamination degree of total petroleum hydrocarbons for the stations are; station 1; 10.913±2.2022ml/l, station 2; 7.645±2.683ml/l, station 3; 9.074±2.1654ml/l and station 4; 12.212±3.3034ml/l. the various concentration levels showed that station 4 > 1 > 3 > 2. the mean concentration level of total petroleum hydrocarbons for the stations is 9.961±2.5885ml/l. the average level of concentration of total petroleum hydrocarbons recorded in this research work in the orashi rivers, in the stations were slightly above or below the national acceptable limit of 10.00mg/l in surface and groundwater set by dpr and fepa [47, 48]. however, it is lower than euepa acceptable limit of 300µg/l in river water [49]. the recorded mean concentration of contamination of total petroleum hydrocarbons in this work was found to be lower than that recorded by ogeleka, et al. [35] in the odidi and egwa riverine areas of warri delta state which was 97592±46 and 91590±51mg/l. the present result obtained is also lower than that reported by alinnor and nwachukwu [50], the concentration obtained ranged within 23.6±4.3mg/l, while investigating the level of total petroleum hydrocarbons. in the work of howard, et al. [51], the mean concentration of hydrocarbon was found to be 33076.00µg/l, which is higher than the level obtained in this study. daniel and nna [7], which recorded between 9.6820±0.233-24.85462±8.058mg/l and that of inyang, et al. [3], which recorded a range of 63.52 to 183µg/l were all above what was obtained in this work. however, the observed mean concentration value of total petroleum hydrocarbons recorded in this work were found to be above that recorded by edori and kpee [52], on a work carried out in the taylor creek, which recorded as low as 2.461±2.687 to 10.009±4.145ml/l in the stations. the investigation by ikpe, et al. [44], of total petroleum hydrocarbons in ethiope river, oghara community revealed that mean concentration was as low as 0,004±0.003 and 0,008±0.008mg/l and in isibor and freeman [53], total petroleum hydrocarbons concentration recorded was between range of not detected to 3.69±0.19mg/l, in a work conducted in egboko river, which were far lower than that obtained from this work. in other parts of the world, total petroleum hydrocarbons concentration in surface water have been reported, such include the work of suratman [54], in the johor peninsular, malaysia which reported a level of 25-2795µg/l, also the work of sammarco, et al. [55] on the deepwater horizon gulf of mexico which recorded a range of 60,000-260,000µg/l of total petroleum hydrocarbons, and petroleum hydrocarbons pollution level recorded by sari and trihadiningrum [56], in wonocolo oil field was 211,025.73µg/l were all higher than that obtained from this work. the presence of total petroleum hydrocarbons in orashi river was not uniform, there were clear variation from station to station. this is a clear indication that the source of pollution was anthropogenic [7, 52]. the flow of the rivers and the pattern of wind direction prevalent in the river must have occasioned the non-availability of the lower fractions of total petroleum hydrocarbons. the lower hydrocarbon components of total petroleum hydrocarbons evaporate with ease from the water surface as a result of high temperature and strong wind and thereby not readily available in the water surface/column to be accounted for daniel and nna [7]; ashiru and ogundare [57]; edori and kpee [52]. there is a noticeable absence or near absence of the higher components of total petroleum hydrocarbons in the surface water which may be that since they are heavier, they might have dropped to the sediments or that the crude oil produced in this area contains little measure of the higher components [52]. asian review of environmental and earth sciences, 2021, 8(1): 68-76 72 © 2021 by the authors; licensee asian online journal publishing group table-1. mean (x ± sd) concentrations (mg/l) of total petroleum hydrocarbons in surface water of orashi river from different stations. carbon length stations 1 2 3 4 c8 0.238±0.016 0.789±0.053 c9 0.045±0.005 0.040±0.002 c10 0.048±0.005 0.017±0.006 c11 0.918±0.084 0.055±0.002 c12 0.641±0.068 0.234±0.051 c13 0.426±0.007 0.197±0.012 c14 0.216±0.006 0.070±0.001 3.237±1.290 c15 0.616±0.065 0.479±0.019 c16 0.642±0.072 0.789±0.028 c17 1.020±0.610 0.493±0.020 3.124±1.080 c18 0.456±0.026 1.635±0.640 0.387±0.010 0.078±0.005 c19 0.545±0.029 3.110±1.280 2.292±0.710 0.526±0.020 c20 1.755±0.580 0.671±0.830 0.962±0.060 0.153±0.009 c21 c22 0.113±0.003 0.655±0.056 2.478±0.790 c23 c24 0.344±0.006 1.213±0.600 0.295±0.018 c25 c26 1.222±0.540 2.229±0.680 1.067±0.530 0.183±0.013 c27 c28 0.577±0.030 0.620±0.021 c29 c30 0.535±0.028 0.603±0.052 0.170±0.009 c31 c32 0.103±0.003 0.034±0.001 c33 c34 0.453±0.020 0.046±0.001 c35 ± c36 ± c37 ± c38 ± c39 ± c40 ± note: total 10.913±2.202 7.645±2.683 9.074±2.165 12.212±3.303 the level at which total petroleum hydrocarbons were found in the sediments of orashi river in the stations were recorded in table 2. in table 2, the level at which total petroleum hydrocarbons have contaminated the sediments in the various stations revealed that station 1;22.3925±5,2104ml/kg, station 2; 35.1071±9.9652ml/kg, station 3; 50.4431±15.9916ml/kg and station 4; 29.3869±8.041ml/kg. the degree of contamination in the various stations showed that station 3> station 2 > station 1. the average concentration level for the stations is 34.3324±9.8021ml/kg. the mean value obtained for total petroleum hydrocarbons in the orashi river for the stations were above the acceptable range given by the federal ministry of environment of 30mg/kg in water [58] and below the directorate of petroleum resources acceptable limit of 50mg/kg and far below the 5000mg/kg intervention limit set by dpr [59]. the mean concentration of total petroleum hydrocarbons recorded in this work were below or lower than that obtained in the work of ogeleka, et al. [35], in egwa (215700±77mg/kg) and odidi (215730±81mg/kg). the work of etchie, et al. [60], the result obtained for total petroleum hydrocarbons in sediment and soil ranged between 600 to 2300mg/kg, and in adewuyi, et al. [39], the mean concentration level of total petroleum hydrocarbon recorded was 1602.4±115.3mg/kg in the ubeji river, warri, delta state, nigeria, were all above that recorded in this study. total petroleum hydrocarbon recorded in the sediment of qua-iboe river by inyang, et al. [3], had a mean value of 606.83±229.48mg/kg, and in ezekwe and utong [61], the total hydrocarbon recorded in the oturuba creek ranged between 1546 to 3997.9mg/kg in the dry season and between 1727.5 to 5118.5 mg/kg in the wet season and in adeniji, et al. [62], from sediment samples in the bufalo river estuary, cape province, south africa was of the range of 1259 to11,000mg/kg, were all higher than the result from this work. however, in the work of edori. and marcus [63], in the sediments of taylor creek recorded an average value of 18.034 to 23.64 mg/kg in the months of study were lower than this work. also, in ashiru and ogundare [57], the concentration of the total petroleum hydrocarbon on the sediments of ugbo water way recorded as low as 0.131mg/kg, which is far lower than that recorded in this work. other cases found to be lower than this work occur in the northwest of the persian gulf with a total mean value of total petroleum hydrocarbons of 45.94µg/g, and that of adeniji, et al. [64] in the sediments of algoa bay, south africa with a range of 0.72 to 27.03mg/kg. the pollution level of total petroleum hydrocarbons in the sediments of rivers can be classified into four levels as in massoud, et al. [65] and ritchie, et al. [66]. the four levels are (10-15 mg/kg) as unpolluted, (15-50 mg/kg) as slightly polluted, (50-200 mg/kg) as moderately polluted and (> 200 mg/kg) as heavily polluted. although the level of contamination in this work averagely sum up within 15-50 mg/kg, it shows that activities such as crude refining, for self-sustenance prevalent in the area and the inability of the nigerian government to make room for adequate clean-up has given rise to such pollution as experienced. sediment acts as natural sink to absorb the contaminants in the water ecological systems. when significant level of pollution due to contamination of the sediments occur, there is the possibility of loss of species and the biodiversity of the ecological frame are completely affected [67]. this situation affects the food chain of the lower asian review of environmental and earth sciences, 2021, 8(1): 68-76 73 © 2021 by the authors; licensee asian online journal publishing group (bottom) and upper levels of the ecosystem [68]. the impact of the contamination might have direct toxic effect on the bottom dwelling animals and can also negatively affect humans through consumption of fishes or water from such contaminated rivers. therefore, there is need for proper sediment quality analysis in order to monitor the river ecological systems [69]. petroleum hydrocarbons manifest toxic effects even at low concentration range of 10-2-1—5 mg/dm3 and affects aquatic creatures in their developmental stages [70]. the presence of total petroleum hydrocarbons in sediment bring about changes in the pattern of the naturally ecosystem, by altering the metabolic processes and reducing the species present and in general create instability in the ecosystem [71]. petroleum hydrocarbons when present in the sediment can hinder and reduce the growth of phytoplanktons. hydrocarbons when carried into the river, may take a long period before being flushed out of the system. the process involved include, dissolution, evaporation, dispersion, emulsification, biodegradation and sedimentation which finally deposits at the bottom of the river. this give severe impact on the aquatic life, as total petroleum hydrocarbons may be buried in the sediment for years without changes in the level of concentration [72, 73]. table-2. mean (x ± sd) concentrations (ml/kg) of total petroleum hydrocarbons in sediments of orashi river from different stations. carbon length stations 1 2 3 4 c8 1.7032±0.191 2.7356±0.920 1.9455±0.210 c9 2.9561±0.980 0.0400±0.001 1.7869±0.193 c10 1.0795±0.152 0.6757±0.059 0.0166±0.000 4.9589±2.010 c11 2.3325±0.510 1.5760±0.113 5.0552±2.210 3.7422±1.500 c12 0.3750±0.053 3.4437±1.361 0.2337±0.007 3.3006±1.350 c13 2.1475±0.500 0.8432±0.691 0.1973±0.004 2.5837±0.810 c14 0.5455±0.021 3.2802±1.260 0.9138±0.087 1.7578±0.190 c15 1.4411±0.170 0.0001±0.000 4.6373±2.001 0.0609±0.001 c16 0.3565±0.010 5.3259±2.250 c17 8.7569±3.310 2.1646±0.821 1.3141±0.100 1.5516±0.112 c18 0.1246±0.005 0.0957±0.001 1.4704±0.112 1.8201±0.195 c19 0.6142±0.051 1.4701±0.110 0.9364±0.093 3.1738±1.320 c20 0.2129±0.005 5.0101±2.100 1.3730±0.110 0.7020±0.061 c21 0.2382±0.005 c22 0.1055±0.005 0.5597±0.022 8.3667±3.291 0.1506±0.005 c23 1.1883±0.210 c24 0.4722±0.063 0.6925±0.056 0.5272±0.053 0.0695±0.001 c25 1.3067±0.191 c26 0.0164±0.000 2.1947±0.834 1.8723±0.196 0.2165±0.005 c27 0.5790±0.026 c28 0.0742±0.001 1.5143±0.120 10.5481±4.010 0.2233±0.006 c29 0.3011±0.007 c30 0.9719±0.071 0.3011±0.007 0.7920±0.071 0.6370±0.056 c31 2.1275±0.731 c32 1.7219±0.182 0.8226±0.065 1.1392±0.200 0.2158±0.005 c33 c34 1.0442±0.101 0.0248±0.001 1.9929±0.213 0.4902±0.010 c35 0.0263±0.001 c36 0.0247±0.001 0.7754±0.063 c37 0.0283±0.001 c38 c39 0.0477±0.002 c40 note: total 22.3925±5.2104 35.1071±9,9652 50.4431±15.9916 29.3869±8.041 table 3 showed the partition coefficient of the orashi river. the partition coefficient is used to explain the preferred stable phase of petroleum hydrocarbon fractions in a river. results from table 3 showed that sediment phase is preferred above the surface water phase, which may be as a result of the hydrophobic nature of water. from table 3, values that are greater than one indicates preference for sediments while values which are less than one shows that the fraction is water loving. the results indicated that the c12 fraction had values less than one, it therefore means that it prefers the water phase, while other fractions were greater than one showing that they are sediment loving. the c16, c18, c22, c28, c30, c32 hydrocarbon components were either more in the water phase or sediment phase. this may be due the pattern of river flow at the sampling station or disturbances occasioned by the operators of illegal oil bunkering and associated businesses within the stations or the possibility of fresh discharge into the river during the sampling period. the higher contamination experienced in the sediment as compared to the surface water may be due to the hydrophobic nature of total petroleum hydrocarbons. sediments acts as sink to hydrophobic compounds and this leads to accumulation. the rate at which these compounds decomposes will increase the concentration of the various compounds [74, 75]. the total petroleum hydrocarbons components due to their hydrophobic nature have affinity for solid particles instead of water [76, 77]. this removes the fractions from the water phase, thereby enhancing the higher concentration of total petroleum hydrocarbons on the sediment phase. the tendency for total petroleum hydrocarbons to have higher concentration in the sediments as compared to the surface water also comes from the fact that complex fractions /components of the hydrocarbon residue are more in the sediment because they sink and settle down to become part of the sediments [77]. this also assert and confirm to the fact that heavier fractions of crude oil (residue) are solids, and hence they prefer the bottom sediments of the river. wakeman and themelis [78], agreed that contaminants that are introduced from land base asian review of environmental and earth sciences, 2021, 8(1): 68-76 74 © 2021 by the authors; licensee asian online journal publishing group runoffs into surface water are quickly attached by suspended particles and thereby rapidly making the contaminant to settle to the bottom of the river which then increases the concentration. this further proves how the sediment is significant in the role of being a natural sink for the marine environment [33]. table-3. partition coefficient of total petroleum hydrocarbon between sediment and water phases in orashi river. carbon length stations 1 2 3 4 c8 3.4672 c9 1.0000 c10 23.9889 0.9765 c11 2.5408 91.9127 c12 0.5850 0.9987 c13 5.0411 1.0015 c14 2.5255 13.0543 0.5430 c15 2.3394 0.1271 c16 0.5553 c17 8.5852 2.6655 0.4967 c18 0.2732 0.0585 3.7995 23.3346 c19 1.1270 0.4727 0.4086 6.0338 c20 0.1213 7.4666 1.4272 4.5882 c21 c22 0.9336 12.7736 0.0608 c23 c24 1.3727 0.4346 0.2356 c25 c26 0.0134 0.9846 1.7547 1.1831 c27 c28 0.1286 0.3602 c29 c30 1.8166 1.3134 3.7471 c31 c32 1.8166 6.3471 c33 c34 2.3051 10.6565 c35 c36 c37 c38 c39 c40 4. conclusion the study indicated that the surface water samples and the sediment samples collected and analyzed from the different stations of orashi river were affected by total petroleum hydrocarbons contamination due to the activities carried out by man in the area that was under investigation. the results obtained from the stations investigated were slightly above or below the 10mg/l approved by dpr in water and below the 50mg/kg allowed by the same body in sediments. the contamination of petroleum hydrocarbons has affected the inhabitants in terms of fishing and farming since it has interfered with their mode of living. the proper estimation and ecological risk assessment should be carried out in the area to ascertain the contamination level of total petroleum hydrocarbons in the river and the possible effect occasioned by the pollution on the inhabitants and possible solutions given in order to mitigate and forestall such occurrence in the future. references [1] g. a. ekaete, k. o. ibironke, s. p. olatunde, and o. p. olaoye, "heavy metal pollutions and its associated ecological risks in lagos lagoon sediments, south-western nigeria," american chemical science journal, vol. 9, pp. 1-13, 2015. [2] r. j. naiman and m. g. turner, "a future perspective on north america's freshwater ecosystems," ecological applications, vol. 10, pp. 958-970, 2000.available at: https://doi.org/10.1890/1051-0761(2000)010[0958:afpona]2.0.co;2. [3] s. e. inyang, a. b. aliyu, and a. o. oyewale, "total petroleum hydrocarbon content in surface water and sediment of qua-iboe river, ibeno, akwa-ibom state, nigeria," journal of applied sciences and environmental management, vol. 22, pp. 1953-1959, 2018.available at: https://doi.org/10.4314/jasem.v22i12.14. [4] o. s. brraich and s. jangu, "evaluation of water quality pollution indices for heavy metal contamination monitoring in the water of harike wetland (ramsar site), india," international journal of scientific and research publications, vol. 5, pp. 1-6, 2015. [5] u. mendie, the nature of water. the theory and practice of clean water production for domestic and industrial use vol. 1. lagos: lactomedals publishers, 2005. [6] g. w. vanloon and s. g. duffy, the hydrosphere. in: environmental chemistry: a global perspectives, 2nd ed. new york: oxford university press, 2005. [7] i. e. daniel and p. j. nna, "total petroleum hydrocarbon concentration in surface water of cross river estuary, niger delta nigeria," asian journal of environment and ecology, vol. 1, pp. 1-7, 2016.available at: https://doi.org/10.9734/ajee/2016/31102. [8] a. c. chindah, s. a. braide, and o. c. sibeudu, "distribution of hydrocarbons and heavy metals in sediment and crustacean (shrimps – penaeus notialis) from the bonny/ the new calabar river estuary," niger delta, ajeam-ragee, vol. 9, pp. 1-17, 2004. [9] v. emongore, e. kealotswe, s. sankwasa, and s. keikanetswe, "pollution indicators in gaborone industrial effluents," journal of applied science, vol. 5, pp. 147-150, 2005. [10] d. lima, m. m. santos, a. m. ferreira, c. micaelo, and m. a. reis-henriques, "the use of the shanny lipophrys pholis for pollution monitoring: a new sentinel species for the northwestern european marine ecosystems," environment international, vol. 34, pp. 94-101, 2008. asian review of environmental and earth sciences, 2021, 8(1): 68-76 75 © 2021 by the authors; licensee asian online journal publishing group [11] s. m. sebastián, b. armstrong, j. a. córdoba, and c. stephens, "exposures and cancer incidence near oil fields in the amazon basin of ecuador," occupational and environmental medicine, vol. 58, pp. 517-522, 2001.available at: https://doi.org/10.1136/oem.58.8.517. [12] r. b. jackson, a. vengosh, t. h. darrah, n. r. warner, a. down, r. g. poreda, g. osborn, k. zhao, d. s. j. jones, and p. r. pujado, handbook of petroleum processing. berlin, germany: springer, 2006. [13] j. d. karr, "increased stray gas abundance in a subset of drinking water wells near marcellus shale gas extraction," proceeding of national academy of science, usa, vol. 110, pp. 11250-11255, 2013.available at: https://doi.org/10.1073/pnas.1221635110. [14] m. moslen and c. miebaka, "hydrocarbon contamination of sediments in the niger delta region: a case study of the azuabie creek, upper reaches of the bonny estuary, nigeria," journal of environmental science, toxicology and food technology, vol. 11, pp. 26-32, 2017. [15] nrc, oil in the sea 111; inputs, fates and effects vol. 265. washington dc, usa: national academic press, 2003. [16] d. a. azevedo, c. y. m. santos, and f. r. aqumoneto, "identification of seasonal variation of atmospheric organic pollutants in campos dos goytacazus, brazil," atmospheric environmental journal, vol. 36, pp. 2383-2395, 2002. [17] o. wokoma, "levels of total hydrocarbon in water and sediment of a polluted tidal creek, bonny river, niger delta, nigeria," international journal of scientific & technology research, vol. 3, pp. 351-354, 2014. [18] j. f. n. abowei, "survival and growth responses of tilapia guineensis (blecker, 1862) fingerlings exposed to various levels of crude oil in the laboratory," msc thesis, department of applied and environmental biology, rivers state university of science and technology, port harcourt, 1996. [19] atsdr, toxicological profile for total petroleum hydrocarbon (tph), us department of health and human services. washington, usa: public health service, 1999. [20] a. e. ite.., t. a. harry, c. o. obadimu, e. r. asuaiko, and i. j. inimi, "petroleum hydrocarbons contamination of surface and ground in the niger delta region of nigeria," journal of environment pollution and human health, vol. 6, pp. 51-61, 2018.available at: https://doi.org/10.12691/jephh-6-2-2. [21] k. z. kponee, a. chiger, i. i. kakulu, d. vorhees, and w. heiger-bernays, "petroleum contaminated water and health symptoms: a cross-sectional pilot study in a rural nigerian community," environmental health, vol. 14, pp. 1-8, 2015.available at: https://doi.org/10.1186/s12940-015-0073-0. [22] a. e. ite and k. j. semple, biodegradation of petroleum hydrocarbons in contaminated soils. microbial biotechnology: energy and environment, r. arora ed. wallingtord: oxfordshire cab international, 2012. [23] a. e. ite. and u. j. ibok, "gas flaring and venting associated with petroleum exploration and production in the nigeria’s niger delta," american journal of environmental protection, vol. 1, pp. 70-77, 2013.available at: https://doi.org/10.12691/env-1-4-1. [24] o. h. yakubu, "addressing environmental health problems in ogoniland through implementation of united nations environment program recommendations: environmental management strategies," environments, vol. 4, p. 28, 2017.available at: https://doi.org/10.3390/environments4020028. [25] o. r. ogri, "a review of the nigerian petroleum industry and the associated environmental problems," environmentalist, vol. 21, pp. 11-21, 2001. [26] p. scheren, a. ibe, f. janssen, and a. lemmens, "environmental pollution in the gulf of guinea–a regional approach," marine pollution bulletin, vol. 44, pp. 633-641, 2002.available at: https://doi.org/10.1016/s0025-326x(01)00305-8. [27] p. c. nwilo and o. t. badejo, "oil spill problems and management in the niger delta," presented at the international oil spill conference miami florida, usa, 2000. [28] c. okoye and l. okunrobo, "impact of oil spill on land and water and its health implications in odu-gboro community, sagamu, ogun state, nigeria," world journal of environmental engineering science and technology, vol. 1, pp. 1-21, 2014. [29] a. a. adeniyi and j. a. afolabi, "determination of total petroleum hydrocarbons and heavy metals in soils within the vicinity of facilities handling refined petroleum products in lagos metropolis," environment international, vol. 28, pp. 79-82, 2002. [30] l. c. osuji and s. o. adesiyan, "the isiokpo oil-pipeline leakage: total organic carbon/organic matter contents of affected soils," chemistry & biodiversity, vol. 2, pp. 1079-1085, 2005.available at: https://doi.org/10.1002/cbdv.200590077. [31] s. olobaniyi and s. efe, "comparative assessment of rainwater and groundwater quality in an oil producing area of nigeria: environmental and health implications," journal of environmental health research, vol. 6, pp. 111-118, 2007. [32] t. monazami, gh, h. rosli, a. sulaiman, b. t. sany, a. salleh, f. owfi, a. savari, r. k. jazani, and z. m. tehrani, "petroleum hydrocarbon assessment in the wastewaters of petrochemical special economic zone and sediment benchmark calculation of the coastal area-northwest of the persian gulf," iranian journal of fisheries sciences, vol. 13, pp. 119-134, 2014. [33] f. d. udoh and m. akpan, "effect of oil spillage on alakiri community in okrika local government area of rivers state, nigeria," journal of industrial pollution control, vol. 26, pp. 139-143, 2010. [34] m. c. blackburn, a. s. mazzacano, and c. fallon, "oil in our oceans: a review of impacts of oil spills on marine invertebrates," ed portland, oregon, usa: matthew shepherd, printing, 2014, p. 152. [35] d. f. ogeleka, o. edjere, a. nwudu, and f. e. okieimen, "ecological effects of oil spill on pelagic and bottom dwelling organisms in the riverine areas of odidi and egwa in warri, delta state," journal of ecology and the natural environment, vol. 8, pp. 201-211, 2016.available at: https://doi.org/10.5897/jene2016.0593. [36] y. k. kharaka, j. s. hanor, d. h. heinrch, and k. t. karh, "deep fluids in the continents: i. sedimentary basins, treatise on geochemistry," ed oxford, uk: pergamon, 2007, pp. 1-48. [37] f. o. arimoro, j. e. uku, and n. o. odume, "effects of petroleum pollution in niger delta wetlands: interplay between the social and ecological systems. recent advances in environmental science from the euro-mediterranean and surrounding regions," in proceedings of euro-mediterranean conference for environmental integration (emcei-1), tunisia 2017, kallel, a., ksibi, m., ben dhia, h. and khelifi, n. eds cham. springer international publishing, 2018, pp. 151-152. [38] o. u. eka and i. r. udotong, a case study of effects of incessant oil spills from mobil producing nigeria unlimited on human health in akwaibom state. in: environmental pollution management in the tropics vol. 14: edited by adinna, e.n, 2003. [39] g. o. adewuyi, o. t. etchie, and o. t. ademoyegun, "determination of total petroleum hydrocarbon and heavy metals in surface water and sediment of ubeji, warri, nigeria," bioremediation, biodiversity and bioavailability, vol. 5, pp. 46-51, 2011. [40] w. guo, m. he, z. yang, c. lin, and x. quan, "aliphatic and polycyclic aromatic hydrocarbons in the xihe river, an urban river in china's shenyang city: distribution and risk assessment," journal of hazardous materials, vol. 186, pp. 1193-1199, 2011.available at: https://doi.org/10.1016/j.jhazmat.2010.11.122. [41] a. hajisamoh, "pollution levels of 16 priority pahs in the major rivers of southern thailand," research and reviews: journal of chemistry, vol. 2, pp. 7-11, 2013. [42] s. uzoekwe and f. oghosanine, "the effect of refinery and petrochemical effluent on water quality of ubeji creek warri, southern nigeria," ethiopian journal of environmental studies and management, vol. 4, pp. 107-116, 2011.available at: https://doi.org/10.4314/ejesm.v4i2.12. [43] w. ashraj, "accumulation of heavy metals in kidney and heart tissues of epinephelus microdon fish from the arabian gulf," environmental monitoring and assessment, vol. 101, pp. 311-316, 2005.available at: https://doi.org/10.1007/s10661-005-0298-4. [44] e. e. ikpe, a. e. akpakpan, e. w. nsi, and a. n. ekanem, "determination of the level of petroleum hydrocarbon in water, fishes and plants from part of river ethiope, ogara in delta state, nigeria," international journal for research in applied chemistry, vol. 2, pp. 1-10, 2016. [45] lawi, for the determination of total petroleum hydrocarbon in soil /sediment/sludge in gas chromatography vol. 9. lagos, nigeria: fugro (nig). ltd, 2011. [46] j. e. cortes, a. suspes, s. roa, c. gonzález, and h. e. castro, "total petroleum hydrocarbons by gas chromatography in colombian waters and soils," american journal of environmental science, vol. 8, pp. 396-402, 2012.available at: https://doi.org/10.3844/ajessp.2012.396.402. [47] fepa, "guidelines and standards for environmental pollution control in nigeria," ed lagos, nigeria: fepa, 2003, p. 238. [48] dpr, environmental guidelines and standards for the petroleum industry in nigeria (egaspin). lagos, nigeria: universal press, 2011. asian review of environmental and earth sciences, 2021, 8(1): 68-76 76 © 2021 by the authors; licensee asian online journal publishing group [49] euepa, "framework for the use of rapid measurement techniques (rmt) in the risk management of sediment and water contamination," uk, directorate-general for environment european commission 1049 bruxelles/brussel belgium, 2009. [50] i. j. alinnor and m. a. nwachukwu, "determination of total petroleum hydrocarbon in soil and groundwater samples in some communities in rivers state, nigeria," journal of environmental chemistry and ecotoxicology, vol. 5, pp. 292-297, 2013. [51] i. c. howard, u. u. gabriel, and m. horsfall, "evaluation of total hydrocarbon levels in some aquatic media in an oil polluted mangrove wetland in the niger delta," applied ecology and environmental research, vol. 7, pp. 111-120, 2009.available at: https://doi.org/10.15666/aeer/0702_111120. [52] e. s. edori and f. kpee, "total petroleum hydrocarbon concentration in surface water from taylor creek, rivers state, nigeria," chemistry research journal, vol. 4, pp. 1-8, 2019. [53] p. o. isibor and o. e. freeman, "evaluation of some heavy metals and total petroleum hydrocarbon in water and palaemonid shrimps (macrobrachium vollenhoenii) of egboko river, warri, delta state, nigeria," 2016. [54] s. suratman, "distribution of total petrogenic hydrocarbon in dungun river basin, malaysia," oriental journal of chemistry, vol. 29, pp. 77-80, 2013.available at: https://doi.org/10.13005/ojc/290112. [55] p. w. sammarco, s. r. kolian, r. a. warby, j. l. bouldin, w. a. subra, and s. a. porter, "distribution and concentrations of petroleum hydrocarbons associated with the bp/deepwater horizon oil spill, gulf of mexico," marine pollution bulletin, vol. 73, pp. 129-143, 2013.available at: https://doi.org/10.1016/j.marpolbul.2013.05.029. [56] g. l. sari and y. trihadiningrum, "petroleum hydrocarbon pollution in soil and surface water by public oil fields in wonocolo sub-district, indonesia," journal of ecological engineering, vol. 19, pp. 184-193, 2018.available at: https://doi.org/10.12911/22998993/82800. [57] o. r. ashiru and m. o. ogundare, "an assessment of total petroleum hydrocarbon and trace metal concentration in the sediment of ugbo water way south western nigeria," african journal of environmental science and technology, vol. 13, pp. 13-21, 2019.available at: https://doi.org/10.5897/ajest2018.2578. [58] fme, "guidelines and standards for environmental pollution in nigeria," ed lagos, nigeria: federal environmental protection agency, 1991, p. 238. [59] dpr, "egaspin soil/sediment target and intervention values for mineral oil (or tph),‖ in environmental guidelines and standards for the petroleum industry in nigeria." vol. 2, ed lagos, nigeria: department of petroleum resources (dpr), 2002, pp. 1-415. [60] t. o. etchie, a. t. etchie, and g. o. adewuyi, "source identification of chemical contaminants in a rural settlement," research journal of environmental sciences, vol. 5, pp. 730-740, 2011.available at: https://doi.org/10.3923/rjes.2011.730.740. [61] c. i. ezekwe and i. c. utong, "hydrocarbon pollution and potential risk of heavy metals in the sediments of oturuba creek, niger delta, nigeria," journal of environmental geography, vol. 10, pp. 1-10, 2017.available at: https://doi.org/10.1515/jengeo-20170001. [62] a. o. adeniji, o. o. okoh, and a. i. okoh, "petroleum hydrocarbon profiles of water and sediment of algoa bay, eastern cape, south africa," international journal of environmental research and public health, vol. 14, p. 1263, 2017.available at: https://doi.org/10.3390/ijerph14101263. [63] e. s. edori. and a. c. marcus, "total petroleum hydrocarbons content of taylor creek, rivers state, niger delta nigeria," international journal of advanced research in chemical science, vol. 6, pp. 16-23, 2019.available at: https://doi.org/10.20431/23490403.0612003. [64] a. o. adeniji, o. o. okoh, and a. i. okoh, "petroleum hydrocarbon fingerprints of water and sediment samples of buffalo river estuary in the eastern cape province, south africa," journal of analytical methods in chemistry, vol. 25, pp. 1-13, 2017.available at: https://doi.org/10.1155/2017/2629365. [65] m. massoud, f. al-abdali, a. al-ghadban, and m. al-sarawi, "bottom sediments of the arabian gulf—ii. tph and toc contents as indicators of oil pollution and implications for the effect and fate of the kuwait oil slick," environmental pollution, vol. 93, pp. 271-284, 1996.available at: https://doi.org/10.1016/s0269-7491(96)00042-5. [66] g. d. ritchie, k. r. still, w. k. alexander, a. f. nordholm, c. l. wilson, j. rossi iii, and d. r. mattie, "a review of the neurotoxicity risk of selected hydrocarbon fuels," journal of toxicology and environmental health part b: critical reviews, vol. 4, pp. 223-312, 2001.available at: https://doi.org/10.1080/10937400118874. [67] d. l. markovic, "untreated municipal waste discharge in victoria bight, british columbia, canada: an investigation of sediment metal contamination and implications for sustainable development," m. sc. thesis. sciences, technology and environment division royal roads university, canada, 2003. [68] g. a. burton jr, "sediment quality criteria in use around the world," limnology, vol. 3, pp. 65-76, 2002. [69] usepa, "sediment classification methods compendium," sediment oversight technical committee office of water (wh-556). epa 823-r-92-006, epa work assignment manager, washington, d. c, usa, pp 2301992. [70] v. kurylenko and o. izosimova, "study of the impact of petroleum hydrocarbons on sea organisms," journal of ecological engineering, vol. 17, pp. 26-29, 2016. [71] t. f. kurochkina, "environmental safety during exploration in the north caspian," natural nauki, vol. 4, pp. 235-237, 2008. [72] s. r. wild and k. c. jones, "polynuclear aromatic hydrocarbons in the united kingdom environment: a preliminary source inventory and budget," environmental pollution, vol. 88, pp. 91-108, 1995.available at: https://doi.org/10.1016/02697491(95)91052-m. [73] c. m. reddy, t. l. eglinton, a. honnshell, w. h. k., l. xu, r. b. gaines, and g. s. frysinger, "the west falmouth oil spill after thirty years:  the persistence of petroleum hydrocarbons in marsh sediments," environmental science and technology, vol. 36, pp. 754–4, 2002.available at: https://doi.org/10.1021/es020656n. [74] environment canada, "toxic chemicals in atlantic canada-polyaromatic hydrocarbons (pah)," ed ottewa: government of canada, 2001, p. 107. [75] p. b. ging, p. c. van metre, and e. callender, "bottom sediments of lorence creek lake, san antonio texas, usa, reflect contaminant trends in an urbanizing watershed," pp. 1-28, 2001. [76] g. kiss, z. vargas-puchony, a. gelembcser, z. krivacsy, a. molnar, and j. hlavay, "survey of concentration of polycyclic aromatic hydrocarbons in lake balaton by hplc with fluorescence detection," chromatography, vol. 48, pp. 149-153, 1998.available at: https://doi.org/10.1007/bf02467532. [77] i. ololade, l. lajide, and i. amoo, "spatial trends of petroleum hydrocarbons in water and sediments," open chemistry, vol. 7, pp. 83-89, 2009.available at: https://doi.org/10.2478/s11532-008-0086-4. [78] t. h. wakeman and n. j. themelis, "a basin-wide approach to dredged material management in new york/new jersey harbor," journal of hazardous materials, vol. 85, pp. 1-13, 2001.available at: https://doi.org/10.1016/s0304-3894(01)00218-7. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 40 © 2023 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 10, no. 1, 40-49, 2023 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v10i1.4539 © 2023 by the authors; licensee asian online journal publishing group experimental determination of the boundaries of the influence of a stope working on the earth's surface filatieva elvira1 olha fursova2 filatiev mikhail3 ( corresponding author) 1department of fire safety, lugansk state university named after vladimir dahl, lugansk region, ukraine. 1email: elafilatyeva@gmail.com 2,3department of technosphere safety, lugansk state university named after vladimir dahl, lugansk region, ukraine. 2email: metmashdtu@gmail.com 3email: mfilatev@gmail.com abstract the theoretical part of the research methodology is developed according to the scheme of subsidence of points on the earth's surface relative to the projection of the face. the curve of the trajectory of the subsidence of the earth's surface is divided by characteristic points at different stages of subsidence of the earth's surface. such stages include: the beginning of the displacement of the earth's surface, the active stage of displacement, the end of the active stage and the attenuation of the processes of subsidence of the earth's surface. according to the goal and the design scheme, on the basis of experimental data, we determined the parameters corresponding to the location of a point on the earth's surface where it began to settle. in relation to the scheme under consideration, three well-known dependencies were analyzed to describe the subsidence curve of the earth's surface: the exponential equation, the hyperbolic tangent function, and the logistic curve. based on them, it was established that the main influencing factor determining the boundary of the dynamic half-mold is the depth of mining operations, and the boundary angles are practically independent of this parameter. keywords: beginning of subsidence, boundary angles, boundary, depth, dynamic semi-trough, earth surface, face, movement, point. citation | elvira, f., fursova, o., & mikhail, f. (2023). experimental determination of the boundaries of the influence of a stope working on the earth’s surface. asian review of environmental and earth sciences, 10(1), 40–49. 10.20448/arees.v10i1.4539 history: received: 3 january 2023 revised: 22 february 2023 accepted: 6 march 2023 published: 20 march 2023 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 41 2. materials and methods ................................................................................................................................................................... 41 3. results and discussion ................................................................................................................................................................... 41 4. conclusions ....................................................................................................................................................................................... 49 references .............................................................................................................................................................................................. 49 mailto:elafilatyeva@gmail.com mailto:metmashdtu@gmail.com mailto:mfilatev@gmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v10i1.4539 https://orcid.org/0000-0002-1041-0535 https://orcid.org/0000-0002-9622-2622 https://orcid.org/0000-0001-5608-6737 asian review of environmental and earth sciences, 2023, 10(1): 40-49 41 © 2023 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this experimental and theoretical studies have made it possible to draw important conclusions for science and industrial activity about the stages of subsidence of the earth's surface. the characteristic points and the curve of dependence of rock subsidence on the degree of development of clearing operations were determined. 1. introduction one of the little-studied issues in the development of coal seams is the reliable determination of the boundaries of the influence of stope workings on the earth's surface. this is confirmed by the results [1] of comparing the experimentally determined sizes of the earth's surface displacement troughs with their parameters calculated according to the normative document [2]. for example, in the conditions of the "stepnaya" mine, the calculated values of the dimensions of the troughs of the earth's surface displacement were significantly less than the experimentally determined parameters. in the conditions of the mine named after p.l. voikov, on the contrary, the experimental values of the dimensions of the displacement troughs of the earth's surface were several times higher than their calculated values. this situation indicates the relevance of work related to the study of the impact of stopes on the earth's surface. the results of such work determine the successful solution of engineering problems on the manifestation of rock pressure on the lining of workings, the establishment of possible water and gas inflows from the undermined coal-rock stratum and environmental consequences. the purpose of the work is to establish the factors that determine the boundary of the dynamic semi-trough on the earth's surface in front of the projection of a moving stope. 2. materials and methods the theoretical part of the research methodology was developed taking into account the scheme of subsidence of the earth's surface [3] relative to the projection of the stope figure 1. in this scheme, instead of time along the abscissa axis, the distances (l) from the projection of the stope line onto the earth's surface to the observation points were plotted. the characteristic points of the curve of subsidence dynamics are: acorresponds to the beginning displacement, o is located in the alignment with a stope and serves as a reference point along the abscissa axis; b the beginning of the active stage; c is the maximum settling rate and the inflection point of the curve, d is the end of the active stage and the beginning of its decay, f is the beginning of the residual effect. the decay stage in the scheme under consideration is limited by the point f. its subsidence ( o ) is approximately 0.97 0.99 of the final ( к ) at the end of the processes of rock compaction [3]. figure 1. scheme of subsidence of the earth's surface relative to the projection of the production face. note: 1 curve of the trajectory of the points of subsidence of the earth's surface; 2 reservoir under development; 3 the position of the stope relative to the curve of the dynamics of subsidence of the earth's surface at the initial moment of influence on point a ; н , к respectively, the initial and final subsidence of the earth's surface; 0 depth of the flat bottom of the shear trough to the compaction of the rocks; ln , lk the distance between the projection of the stope and points a and f , respectively, at the beginning and end of the displacement; δo , γo , βo boundary angles (depending on the direction of mining of the extraction column) that determine the position of point a (the beginning of the earth's surface displacement); stope advancing direction. according to the goal and the design scheme figure 1, on the basis of experimental data, it is necessary to determine for each specific case the parameters that determine the position of point a. these include boundary angles (δo when mining seams along strike, γo along rise, βo along dip), as well as lh the distance from the projection of the production face to point a. 3. results and discussion the division of the process of displacement of undermined rocks and the earth's surface into separate stages was carried out using the recommended [3-5] functions. asian review of environmental and earth sciences, 2023, 10(1): 40-49 42 © 2023 by the authors; licensee asian online journal publishing group as applied to the scheme under consideration figure 1, the dynamics of subsidence of the earth's surface is described by an exponential equation [1]: ( ) ( ) 2 11 exp , l lн l к     − +  = −     (1) where  is the subsidence of the observation point on the earth's surface when its projection is removed at a distance l from the production face, mm; 1  empirical coefficient determined from experimental data. the first three derivatives of the function (1) are the equations of the settling rate, acceleration and acceleration change. the extrema of the obtained dependencies are used to determine the coordinates of the characteristic points, which are used as the boundaries of the displacement stages [3]. in a similar way, the boundaries of the stages of subsidence of the earth's surface are determined based on the extrema of the first two derivatives of the functions of the hyperbolic tangent [4]: ( )  ,)(tan1 321 nlnhnl ++= (2) where n1, n2, n3 are empirical coefficients determined by the least squares method. when constructing the curve of the dynamics of subsidence of the earth's surface from the absolute values of the experimental data according to the function of the hyperbolic tangent, it was found that the coefficient n1 is numerically equal to half of the final subsidence ( 2 1 кn = ). the distance ln figure 1 is determined from the condition н = 0. the minimum value of the function (2) asymptotically approaches zero, therefore, to determine the beginning of the impact of cleaning operations on the earth's surface, an assumption was introduced 0,01 1 dн к =  = к . the parameter ln for this case is determined from equation 2: 2 3 3 2 2 arctan (2 1) 1.946 .н h d n n l n n  − − − = = (3) the derivatives of the hyperbolic tangent function correspond to the dependencies [6]: ( ) ,tan1)( 32 2 21 nlnhnnl +−= , (4)  .)(tan1)(tan2)( 32 2 32 2 21 nlnhnlnhnnl +−+−= . (5) based on the values of the extrema of equations 4, 5, the coordinates of the characteristic points of the curve of the dynamics of subsidence of the earth's surface are determined. the logistic curve equation for describing the dynamics of subsidence of the earth's surface has the form [5]: , )exp(1 )( lcb a l −+ = (6) where a is an empirical coefficient corresponding to the final subsidence of the earth's surface ( к ); b, c empirical coefficients that determine the position of the curve relative to the abscissa axis and the width of the middle section, i.e. the duration of the active stage of subsidence of the earth's surface. the first derivative of equation 6 is characterized by the dependence: ( ) ( ) . exp1 )exp( 2 lcb lccba l −+ − = (7) extreme value of the function ( )l corresponds to the inflection point c of the logistic curve figure 1 with coordinates ( ln , 2 b a c ). the second derivative of the original equation 6: ( ) ( )  ( )3 2 exp1 exp1)exp( lcb lcblccba l −+ −−−− = (8) has two extreme values. the values of these coordinates determine the position of the active stage of subsidence of the earth's surface (points b and d). the parameter ln for the logistic curve (6) was determined from the conditions ккн d  == 01,01 and ка = : 11 1 ln( ) 4.595 ln .н d bbl c c − − = − = − (9) parameter lk found from the condition ккd  )99,097,0(2 == : 21 1 ln 3.892 ln .к d bb l c c −     − − = = − (10) the coordinates of the characteristic points (a, o, b, c, d, f) of the curve of the dynamics of subsidence of the earth's surface, determined according to the initial dependencies (1, 2, 6), are summarized in table 1. asian review of environmental and earth sciences, 2023, 10(1): 40-49 43 © 2023 by the authors; licensee asian online journal publishing group table 1. dependencies for determining the coordinates of the characteristic points of the curve of the dynamics of subsidence of the earth's surface according to the exponential, hyperbolic tangent and logistic equations. characteristic points of the curve of the dynamics of subsidence of the earth's surface figure 1 exponential equation hyperbolic tangent equation logistic equation abscissa l, m ordinate  , mm abscissa l, m ordinate  , mm abscissa l, m ordinate  , mm a нl− 0 2 3298,2 n n+ − 0 c b − − ln595,4 0 o 0 ( ) 2 021 lехрк −−  0  31 tanh1 nn + 0 b к +1  b нl− 1 5246,0  0.241 к 2 3658,0 n n+ − 0.21 к ( ) c b − 73,3ln 0.21 к c нl− 1 7071,0  0.393 к 3 2 n n − 0.50 к c bln 0.50 к d нl− 1 2247,1  0.777 к 2 3658,0 n n− 0.80 к ( ) c b − 268,0ln 0.79 к f ( ) нl d − − − 1 1ln  (0.97÷0.99) к 2 3946,1 n n− (0.97÷0.99) к c bln892,3 − (0.97÷ 0.99) к the next stage of the work was to determine for each object of observation the empirical parameters included in the original equations. for the exponential equation 1 we found the values к , 1  , lh, for the equation 2 of the hyperbolic tangent n1 , n2 , n3 and for the logistic dependence (6) a, b, c. the processing of experimental data, in order to determine the empirical coefficients of equations 1, 2, 3, was carried out by the least squares method. using their numerical values and dependencies to determine the coordinates of characteristic points table 1, we found the boundaries of the stages of subsidence of the earth's surface during the cleanup operations at ten sites table 2. table 2. the results of determining the empirical coefficients and correlation relationships (r) by the least squares method for the objects of observation. mine, reservoir, literary source math functions logistics exponential hyperbolic tangent a = к b c r 1 нl к r n1 = 0.5 к n 2 n 3 r "belozerskaya", [3] 810 4.1 0.016 0.998 2.0 105 810 0.999 405 0.008 -0.70 0.997 №22 "kommunarskaya", 3к , [4] 900 9.3 0.010 0.998 1.0 70 900 0.976 450 0.005 -1.11 0.998 "gramoteinskaya", sychevskyiii, [7] 2375 13.0 0.028 0.999 5.0 thirty 2420 0.987 1180 0.015 -1.28 0.995 appalachian basin mine, [8] 980 26.0 0.040 0.995 6.5 20 1010 0.991 490 0.019 -1.65 0.994 "anniversary", 6с  , [9] 915 12.5 0.050 0.997 1.5 20 910 0.974 458 0.026 -1.27 0.996 them. a.f. zasyadko, t 3 , [10] 400 7.0 0.006 0.997 3.0 70 400 0.974 200 0.003 -1.20 0.996 staszic, 352, [10] 480 4.1 0.020 0.999 5.0 60 980 0.984 490 0.010 -0.70 0.999 ruhr basin mine, grimberg 2/3 , [10] 1420 5.8 0.010 0.998 5.5 200 1420 0.979 710 0.005 -0.87 0.998 them. cm. kirov, po "leninskugol", boldyrevsky, [11] 1300 7.1 0.070 0.996 3.3 21 1310 0.997 638 0.041 -0.98 0.994 "steppe", [12] 832 5.8 0.064 0.996 3.1 20 835 0.994 416 0.029 -0.95 0.995 it should be noted that in most cases the values к , determined using the considered functions, were practically equal to each other. differences, as a rule, did not exceed 1.0% and only in one case (the mine of the appalachian basin), the maximum difference was 3.1%. this indicates the possibility of using any of the considered functions to determine the ordinates of characteristic points. a similar conclusion was reached about the possibility of using the analyzed functions to determine the abscissas of the characteristic points of subsidence of the earth's surface. using the empirical coefficients of the equations table 2 for all mines, we calculated the abscissa ( al ) of the characteristic point a table 3. on the basis of experimental data [7, 13] it was established that the parameters of the trough of displacement of the earth's surface by 80% or more can be determined by the depth of work. to test and confirm this assumption, on the basis of the data table 3, we determined the dependences of the average values of the abscissas of the characteristic point a on the depth of the treatment. the results of these calculations show that the characteristic point abscissas are directly proportional to the mining depth figure 2. in absolute value, the correlation coefficient (r) for different coal basins was equal to 0.89. asian review of environmental and earth sciences, 2023, 10(1): 40-49 44 © 2023 by the authors; licensee asian online journal publishing group table 3. the results of determining the coordinates of the characteristic point a of subsidence of the earth's surface along the abscissa and boundary angles (δo , γo , βo ). mine, reservoir, literary source depth of cleaning operation, h, m the thickness of the developed reservoir, m, m h/m seam dip angle, α, degrees the distance between the projection of the production face and point a, al , m boundary angles, δo , γo , βo , degrees "belozerskaya", [3] 420 1.30 323 12 169 68 no. 22 "kommunarskaya", k 3 , [4] 652 1.47 444 20 178 75 "gramoteinskaya", sychevskyiii, [7] 220 4.50 49 four 57 75 appalachian basin mine, [8] 220 1.65 133 28 83 "anniversary", s 6 , [9] 150 1.00 150 3 34 77 them. a.f. zasyadko, m 3 , [10] 1195 2.10 569 10 292 76 "stashitz", 352, [10] 480 2.10 229 126 75 ruhr mine, grimberg , 2/3, [10] 920 2.20 418 253 75 them. cm. kirov, po "leninskugol", boldyrevsky, [11] 205 1.70 121 6 thirty 82 "steppe", [12] 106 0.91 116 four 37 71 figure 2. dependence of the abscissa la of the characteristic point a on the depth of the cleaning operations h and the parameter h/m. note: 1, 2 averaging direct links la respectively with h and h m; ×, ○ experimental data; r correlation coefficient. a fairly close correlation (r = 0.95) was established between the abscissas la and the relative parameter h/m figure 2. this indicates that the parameter h/m, along with the depth, can determine the boundary of the dynamic trough in front of the projection of the stope. connection of boundary angles (δo , γo , βo) with h and h/m has not been established figure 3. correlation coefficients were respectively 0.13 and 0.25. boundary angles (δo , γo , βo) were in the range of 68-83°, with an average value of 76°. asian review of environmental and earth sciences, 2023, 10(1): 40-49 45 © 2023 by the authors; licensee asian online journal publishing group figure 3. dependence of the boundary angles (δo , γo , βo ) on the depth of treatment operations h and the parameter h/m . note: 1 straight line corresponding to the average values of the angles (76°); ×, ○ experimental values, respectively, of the dependence on h and h/m. mining of coal seams has, first of all, an impact on the displacement of host rocks. as a result, the rock pressure on the lining of the development workings changes, and displacement troughs form on the earth's surface. in one case, the lining of the workings is deformed and the conditions for their maintenance in the zone of influence of the mining operations become much more complicated. in the second, it is necessary to take measures to protect objects on the earth's surface. based on the similar course of the processes of subsidence of the earth's surface and the displacement of rocks under the influence of a moving stope on the contour of sectional workings, an assumption was made about a possible connection between the phenomena under consideration. the establishment of general patterns or differences between the subsidence of the earth's surface and the conditions for maintaining section workings can contribute to the successful solution of many engineering problems. these tasks include the development of rational measures for the protection of objects on the earth's surface and the maintenance of sectional workings in the zone of influence of clearing operations. research in this direction is very relevant. a characteristic feature that combines the subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings is the same type of experimental dependences of the dynamics of the processes under consideration. the common features of these processes include a gradual increase in the subsidence of the undermined rock mass on the contour of the section workings. the intensity of subsidence of the earth's surface and the displacement of rocks increases as the stope approaches. after the passage of the lava, the subsequent attenuation of the processes occurs. the dynamics of subsidence of the earth's surface and the displacement of roof rocks and soil of a sectional mine under the influence of a stope can be described by a diagram figure 4. in this scheme, the abscissa shows the distances ( зl ) from the projection of the stope line onto the earth's surface to the observation points, as well as the distances from the stope ( пl and кl ) to the points of observation of the displacement of soil and roof rocks on the working contour. characteristic points that determine the dynamics of ongoing processes are: па , ка , за correspond to the beginning of the shift of soil rocks and the roof of workings and the earth's surface; по , ко , зо are located in the alignment with the stope and serve as the origin of the coordinate axes; пв , кв , зв the beginning of the active stage of displacement of soil rocks and the roof of workings and subsidence of the earth's surface; пс , кс , зс correspond to the maximum rate of rock displacement and subsidence of the earth's surface and are the inflection points of the curves; пd , кd , зd end of active stages and beginning of attenuation stages; пf , кf , зf the beginning of the residual impact of the stope on the processes under consideration. the decay stages in the scheme are limited by the points пf , кf and зf . the subsidence of the earth's surface at a point зf is approximately 0.97 ÷ 0.99 of the final ( к ) at the end of the rock compaction processes. the end of the processes at the points пf and кf can be established experimentally by comparing their shift with a change in the working contour outside the influence of the stope. according to, when workings are located outside the zone of mining operations, the difference between the roof-soil convergence does not exceed 10%, and the decrease in the design sections of workings is 0.8%. when calculating the coordinates of the points пf and кf , taking into account the above ratios, we used the recommendations. the purpose of the work is to establish, on the basis of experimental data, the characteristic stages of subsidence of the earth's surface and the displacement of soil rocks and the roof of a sectional mine under the influence of a moving stope. asian review of environmental and earth sciences, 2023, 10(1): 40-49 46 © 2023 by the authors; licensee asian online journal publishing group figure 4. the scheme of subsidence of undermined rocks and the earth's surface and soil relative to the face. note: 1 – reservoir under development; 2 stope; 3,4,5 curves characterizing, respectively, the displacement of the soil and the roof of the sectional working and the subsidence of the earth's surface; пl , кl , зl abscissa axes, respectively, for the soil and the roof of the working and the earth's surface; п , к , з y-axis for the soil and the roof of the working and the earth's surface, respectively; па , пв , пс , пd , пf characteristic points of the soil displacement curve; ка , кв , кс , кd , кf characteristic points of the roof displacement curve; за , зв , зс , зd , зf characteristic points of subsidence of the earth's surface. the method of work included several stages: • development of a general scheme for the subsidence of the earth's surface and the displacement of soil rocks and the roof of a sectional mine figure 4; • analysis of the available experimental data on subsidence of the earth's surface and displacement of rocks on the contour of sectional workings; • selection of mathematical dependencies that most accurately describe the processes under consideration and reflect their physical essence; • study of empirical equations obtained on the basis of the accepted mathematical dependence using derivatives to establish the characteristic points of subsidence of the earth's surface and the displacement of rocks on the contour of a sectional working; • determination of the distances from the characteristic points of subsidence of the earth's surface to the projection of the production face ( з al , з вl , з сl , з dl , з fl ) and the removal of characteristic points of displacement of soil and roof rocks from the production face ( п al , п вl , п сl , п dl , п fl and к al , к вl , к сl , к dl , к fl ); • comparison of the established parameters and conclusions about the general or distinctive patterns of the processes under consideration. for the practical implementation of the scheme figure 4, as the initial function describing the processes under consideration, based on the results of work, we took the logistic curve of the form: ( ) )exp(1 lcb a l −+ = , (11) where  is the subsidence of the observation point on the earth's surface or the displacement of rocks on the contour of the working; a is an empirical coefficient corresponding to the final value of subsidence ( к ); b , c are empirical coefficients that determine the characteristic stages of the processes; l distances characterizing the position of points relative to the production face along the abscissa axis. empirical coefficients of equation 11 a, b, c, which correspond to the parameters of subsidence of the earth's surface in the conditions of the stepnaya mine, were determined according to empirical dependencies. it was found asian review of environmental and earth sciences, 2023, 10(1): 40-49 47 © 2023 by the authors; licensee asian online journal publishing group that the coefficients a, b and c depend on the thickness of the developed seam ( t ), the depth of work ( h ), the speed of advancing the stope ( оч ) and the length of the lava ( лl ): )1054,11064,2( 1 34 −− +− = m a , (12) )19,014,0( 1 +− = h b оч , (13) ) 1 ln(0148,0205,0 hlm c л  += . (14) correlation relationships ( r ) for empirical dependences (12,13,14) were respectively 0.881, 0.884 and 0.986. this indicates the possibility of a fairly accurate determination of the coefficients of dependence (11) according to equations 12,13,14. for their calculation, we used the parameters characterizing the operating conditions of the 157th and 161st longwalls of the stepnaya mine ( t = 1.04m, h = 395m, оч =122m/month, лl = 300m). for the specified conditions, the values of the coefficients a, b and c characterizing the subsidence of the earth's surface, respectively, amounted to 809, 6.81 and 0.032. the empirical coefficients of equation 11 for the analytical description of the displacement of roof and soil rocks on the contour of the 159th and 163rd drifts were determined from the results of processing the experimental data using the least squares method figure 5. the established dependencies practically functionally describe the dynamics of rock displacement on the contour of sectional workings (r = 0.964÷0.986). this indicates the possibility of their application in engineering calculations. thus, on the basis of the analysis of the available experimental data, the empirical coefficients of the logistic dependence (1) were determined, characterizing both the subsidence of the earth's surface and the displacement of roof rocks and soil of sectional workings. the use of one initial dependence allows you to establish the degree of closeness or difference between the parameters of subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings. figure 5. dependence of rock displacement (  ) on the contour of the 159th (a) and 163rd (b) drifts on the distance to the stope ( l ) during the development of the 157th 161st lava by the stepnaya mine. note: 1,2 averaging curves for the displacement of rocks, respectively, of the roof and soil; ▲, ■ experimental data; r is the correlation ratio. to establish the stages of the processes of subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings (determining the coordinates of characteristic points), methodological approaches were used to study functions using their derivatives. the results of the study of the logistic curve and the general equations for determining the coordinates of the characteristic points are shown in table 4. substituting the values of the empirical coefficients ( a, b , c ) into these equations, we determined the coordinates of the characteristic points of subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings during the development of the 157th and the 161st lava by the stepnaya mine. based on the numerical values of the coordinates of the characteristic points table 4 and the location of the curves relative to the stope figure 6, a comparative analysis was made of the processes of subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings. asian review of environmental and earth sciences, 2023, 10(1): 40-49 48 © 2023 by the authors; licensee asian online journal publishing group table 4. the results of determining the coordinates of the characteristic points of subsidence of the earth's surface and the displacement of rocks on the contour of the excavation 159th and 163rd drifts of the stepnaya mine. characteristic points of the logistic curve equations for determining the coordinates of the characteristic points of the logistic curve values of empirical coefficients (а, b , c ) of logistic dependence and coordinates of characteristic points ( l ,  ) earth surface 159th drift 163rd drift roof the soil roof the soil abscissa, l , m ordinate,  , mm a=809, b =6.81, c =0.032 a=712, b =0.812, c =0.020 a=497, b =0.631, c =0.021 a=542, b =1.203, c =0.025 a=517, b =1.427, c =0.028 l , m  , mm l , m  ,mm l , m  ,mm l , m  ,mm l , m  ,mm a c b − − ln595,4 0 -84 0 -240 0 -241 0 -176 0 -151 0 o 0 b к +1  0 104 0 393 0 305 0 246 0 213 b c b − )73,3ln( 0.21∙ к 19 170 -76 150 -85 104 -45 114 -34 109 c c bln 0.50∙ к 60 405 -10 356 -22 249 7 271 13 259 d c b − )286,0ln( 0.79∙ к 101 639 17 562 20 393 60 428 60 408 f c bln892,3 − 0.99∙ к 182 801 184 705 163 492 163 537 152 512 figure 6. dependences of the subsidence of points on the earth's surface and the displacement of rocks on the contour of development workings ( ) on their position relative to the stope ( l ) in the conditions of the stepnaya mine. note: 1 curve of subsidence of the earth's surface; 2,4 – roof and soil displacement curves on the contour of the 159th drift; 3.5 roof and soil displacement curves on the contour of the 163rd drift; па , пв , пс , пd , пf characteristic points of displacement of soil rocks; ка , кв , кс , кd , кf characteristic points of displacement of roof rocks; за , зв , зс , зd , зf characteristic points of subsidence of the earth's surface. coefficient a characterizes the end of processes. its maximum value corresponded to the subsidence of the earth's surface (809 mm), which is somewhat less than the recoverable thickness of the developed seam ( t = 1.04 m). the displacement of the roof on the contour of the 159th and 163rd drifts, respectively, reached 705 and 537 mm. the final displacement of the soil in these workings was 492 and 512 mm. the displacement of soil rocks, in terms of the nature of manifestation and the absolute values of the parameters, differs little from the displacement of roof rocks. this is obviously due to the low strength properties of the host rocks. under the conditions of strong asian review of environmental and earth sciences, 2023, 10(1): 40-49 49 © 2023 by the authors; licensee asian online journal publishing group enclosing rocks, the differences in the displacement of the roof and soil of sectional workings should be expected to be more significant. coefficients b and c define the coordinates of the characteristic points along the x-axis. the sizes of individual stages characterizing the intensity of the processes depend on their ratio. the coefficient b = 6.81 for the earth's surface was 5–10 times higher than its value (0.631–1.422) for the circuit of section workings, and the value c = 0.032 was comparable with similar coefficients for workings ( c = 0.020–0.028). different values of the empirical coefficients caused the unequal location of the characteristic points of the shear trough on the day surface and the rocks on the contour of the sectional workings relative to the stope. the beginning of the shift of the roof and soil rocks occurred at a distance of -151 ÷ -241 m (figure 6, table 4), which is much more than the distance from the projection of a point on the earth's surface за to the stope alignment ( аl = -84 m). the beginning of subsidence of the earth's surface corresponds to the beginning of active stages of rock displacement (points пв and кв ) on the contour of workings. in all cases, the active stage of rock movement began ahead of the stope. this indicates that the location of the point за on the earth's surface determines the beginning of the active manifestation of high rock pressure in front of the stope (the zone of hrp). the obtained results indicate the participation of the entire rock mass from the developed reservoir to the earth's surface in the formation of the hrp zones. they are confirmed by directly proportional experimental dependences of rock displacements in workings on the depth of mining. the maximum intensity of rock displacement on the contour of workings was observed figure 6 in the immediate vicinity of the stope at points пс and кс . the active stage of subsidence of the earth's surface occurred (points за , зв , зс ) after the stope passed over the goaf. approximately the same distances (152÷184 m) from the stope (points пf , кf , зf ) corresponded to the end of the processes of subsidence of the earth's surface and the displacement of rocks in the contour of workings. the above experimental and theoretical studies made it possible to draw the following important conclusions for science and production activities: • the beginning of subsidence of the earth's surface corresponds to the beginning of the stage of intensive displacement of the roof and soil rocks ahead of the stope; • the active stage of displacement of rocks in the contour of development workings begins in front of the stope, and ends after its passage; • the active stage of subsidence of the earth's surface occurs above the worked-out space behind the stope; • the processes of subsidence of the earth's surface and the displacement of rocks on the contour of sectional workings stop at approximately the same distance after the passage of the stope. 4. conclusions the conducted research allowed to establish the following: • the main influencing factor that determines the boundary (la) of the dynamic half-trough on the earth's surface in front of the projection of the moving stope is the depth of mining (h). this dependence is directly proportional la=0.263·h ; • boundary angles (δo , γo , βo) practically do not depend on the depth of treatment operations. their values were in the range of 68÷83°, with an average value of 76°. references [1] m. v. filatiev, n. i. antoshchenko, and s. v. pyzhov, "formation of dynamic and stationary semi-molds of the displacement of the earth's surface during mining of coal seams," collection scientific works of donstu, vol. 1, no. 45, pp. 15-24, 2016. [2] ukraine's industry standard, rules for the forgery of buildings, structures and natural objects in the underground mining of coal. kiev, ukraine: gstu, 2004. [3] y. n. gavrilenko, "prediction of earth surface displacements in time" coal of ukraine," kiev, ukraine, vol. 6, no. 6, pp. 45-49, 2011. [4] s. kulibaba and m. rozhko, "timing intensive stage of the process of shifting of the earth surface," scientific works of the national academy of sciences of ukraine, vol. 9, no. 1, pp. 173-179, 2011. [5] l. a. chepurnaya and n. i. antoshchenko, "prediction of zones of gas evolution from undermined rocks and coal seams," coal of ukraine, kiev, ukraine, vol. 4, no. 3-4, pp. 51-54, 2015. [6] s. b. kulibaba, m. d. rozhko, and b. v. khokhlov, "the nature of the development of the process of shifting the earth's surface in time over a moving face, science and technology of ukraine," national academy of sciences of ukraine, kiev, ukraine, vol. 4, no. 7, pp. 40-54, 2010. [7] v. a. nazarenko and y. n.v., "patterns of development of maximum subsidence and inclination of the surface in the displacement mold." dnepropetrovsk: nmu, 2011, p. 91. [8] e. v. babenko, "setting up a model for modeling seismic events of anthropogenic nature", rock pressure problems," donntu, vol. 9, no. 17, pp. 67-93, 2009. [9] s. g. avershin, d. a. kazakovsky, and m. v. m. korotkov, "shift of rocks and the earth's surface in the main coal basins of the ussr," ugletekhizdat, ussr, 1958, p. 251. [10] a. s. yagunov, "investigation of the influence of high speeds of movement of the face on the nature and parameters of the surface displacement process," bulletin of the scientific center for the safety of work in the coal industry, vol. 2, no. №2, pp. 36-43, 2007. [11] y. n. gavrilenko, n. m. papazov, and t. v. morozova, "the dynamics of subsidence of the earth's surface with a large depth of development and a high speed of movement of the face, rock pressure problems," donntu, vol. 4, no. 4, pp. 108-119, 2000. [12] v. larchenko, "the effect of underground mining of coal seams on the state of the earth's surface," vol. 4, no. 12). st. petersburg: maneb newspaper, 1998, pp. 39-41. [13] m. v. filatiev, n. i. antoshchenko, and s. v. pyzhov, "influence of the depth of treatment works on the displacement of the earth's surface," collection scientific works of donstu, vol. 1, no. 44, pp. 29-34, 2015. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 28 © 2023 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 10, no. 1, 28-39, 2023 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v10i1.4440 © 2023 by the authors; licensee asian online journal publishing group an assessment of water quality and the locals' perception of coastal lagoon pollution in ghana: a case study of chemu lagoon in tema kofi adu-boahen1 isaac boateng2 emmanuel yeboah okyere3 sender kyeremeh4 ( corresponding author) 1,3,4department of geography education, university of education, winneba, ghana. 1email: kadu-boahen@uew.edu.gh 3email: eyokyere@uew.edu.gh 4email: k.sender.11@gmail.com 2department construction and wood technology, akenten appiah menkah university of skills training and entrepreneurial development, ghana. 2email: isaac.boateng@uew.edu.gh abstract the chemu lagoon is not immune to pollution through chemical waste contamination, refuse disposals, and untreated household sewage, and hence has been chosen as a case study. this paper aims to assess the lagoon's level of pollution. chemical analysis of water samples, field observations, and a structured survey questionnaire was used to assess the state of the lagoon. the study revealed that the chemu lagoon has inferior water quality as most of the parameters evaluated were above the acceptable standards of the united states environmental protection agency (usepa). significant differences in concentrations of water quality parameters were established between seasons. the study found that respondents were aware of the lagoon’s polluted state and attributed pollution to siltation and waste dumping. this leads to offensive odour, livelihood losses emphasising a reduction in fishing activities, and outbreaks of diseases in the area. conclusively, stakeholders have not prioritised mitigating pollution of the lagoon. the study recommends that the environmental health and waste management departments of the tema metropolitan assembly intensify house-to-house hygiene education and sanitary inspection in the area. there should be education and sensitisation on proper waste management practices in the area. keywords: chemu lagoon, citizen science, lagoon, pollution, waste management, water quality. citation | adu-boahen, k., boateng, i., okyere, e. y., & kyeremeh, s. (2023). an assessment of water quality and the locals’ perception of coastal lagoon pollution in ghana: a case study of chemu lagoon in tema. asian review of environmental and earth sciences, 10(1), 28–39. 10.20448/arees.v10i1.4440 history: received: 15 november 2022 revised: 23 december 2022 accepted: 10 january 2023 published: 30 january 2023 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 29 2. water pollution in ghana .............................................................................................................................................................. 30 3. materials and methods ................................................................................................................................................................... 30 4. results ................................................................................................................................................................................................ 31 5. discussions ........................................................................................................................................................................................ 37 6. conclusions ....................................................................................................................................................................................... 38 references .............................................................................................................................................................................................. 38 mailto:kadu-boahen@uew.edu.gh mailto:eyokyere@uew.edu.gh mailto:k.sender.11@gmail.com mailto:isaac.boateng@uew.edu.gh https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v10i1.4440 asian review of environmental and earth sciences, 2023, 10(1): 28-39 29 © 2023 by the authors; licensee asian online journal publishing group contribution of this paper to the literature relevant studies on lagoons primarily focus on reporting the state of pollution and water quality and, in some instances, identifies impacts on lagoons’ biodiversity by collecting water samples and specimen to investigate in laboratories. this study focuses on lagoon pollution but diversifies to study the case from a citizen science perspective to understand the respondents' perception. 1. introduction lagoons are shallow coastal water bodies, entirely or partly separated from a larger body of water by a barrier, reef or other depositional features [1, 2]. lagoons deliver services, including fisheries, flood control, fresh water, and preservation of an array of species. they also serve as critical roosting, breeding grounds, food sources, and habitats for several bird species, especially migratory ones [3, 4]. on the other hand, lagoons are extraordinarily fragile and vulnerable to natural and human-based factors [4, 5]. natural processes and pollution from nearby urban and industrial development can easily disturb coastal lagoons [3]. the united nations world water assessment programme reiterates that river, pond, dam, ocean, and lagoon pollution is a primary global concern [6, 7]. pollution of a water body is observed whenever a body of water is harmed as a consequence of man's addition of a substantial quantity of hazardous materials. these actions cause adverse effects such as harm to living resources and marine life, dangerous situations to public health, an impediment to coastal and maritime activities, and poor quality use of the water body (united nations convention of the law of the sea; unclos). there are numerous sources of contamination, which can be classified into two categories: primary and secondary causation. primary causes encompass effluent from homes, factories, refineries, and sewage treatment plants that discharge fluids of differing quality directly into the waterways. contaminants that enter water bodies from soils and groundwater structures, as well as from the surrounding air of acid rain, are considered secondary sources [8]. anthropogenic impacts contaminate a large portion of the world's water sources. around 2 million tons of sewage, industrial, and agricultural waste are estimated to be released into the nation's bodies of water as of 2002 united nations world water assessment programme [un wwap] [6]; kwadzo, et al. [9]. in kwadzo, et al. [9], it is reported that plastic and domestic wastes are the major lagoon pollutants identified by the respondents in work conducted on the fosu lagoon in ghana. these negatively influence the environment and the lifestyle of individuals who use polluted water bodies [8]. in ghana and other less economically developed countries where population growth is mainly faster than economic development, waste treatment facilities are almost non-existent. many people die yearly from water-borne diseases such as cholera and typhoid and from pollutants such as lead, cyanide and other metals that cause cancer and death [10]. according to united nations children's fund [11] and the world health organization [12], one of the most effective forms of water pollution is poor sanitary conditions, which pollute water bodies globally. they believe that around 2.5 billion people worldwide cannot access enhanced hygiene. over nine million hectares of mangroves are located around coastal lagoons, tidal estuaries and deltas along the coastal wetlands of west africa [13]. notwithstanding their international importance as conservation areas for global biodiversity and production efficiency, these lagoons and marshes are primarily unrestricted. research has found over 40 coastal lagoons along ghana's 540-kilometre shoreline, which is part of the coast of west africa [3]. these lagoons and their wetlands provide a unique environment and habitat for humans and numerous species of animals in ghana [3]. economic development and population growth have increased the pollution of these water bodies tremendously, and most often, the pollutants are chemical waste, refuse disposals, and untreated sewage from houses. the vulnerability of coastal lagoons to pollution is counter-productive to environmental development. it is graphically illustrated in the niger delta, where mangroves and associated wetlands have been subjected to progressive degradation from the plethora of oil and gas mining activities in the niger delta and the near-shore environment [14]. the collapse of the fishing industry of the aby lagoon in cote d'ivoire in 1981 due to chemical pollution is another example [10]. chemu lagoon is one of ghana's worst-polluted lagoons [15]. according to anny [16], chemu lagoon, which once had the prospect of being a source of sustenance, is almost depleted and is on the brink of total 'death' as a consequence of indiscriminate disposal of solid, liquid, and hazardous wastes. chemu lagoon, which once had the potential to be a suitable habitat for fish and serve as a valuable ecosystem and destination for migratory birds, has nearly dried up and is on the verge of 'death' due to pollution and overcrowding in its watersheds. the lagoon is presumed to be tema's most highly contaminated body of water. for years, city officials have been conscious of the lagoons' poor condition; however, no well-defined implementation plan has been executed to save the lagoons from extermination. the chemu lagoon in tema new town is exposed to vehicle smoke. it is also close to the tema oil refinery, which continuously emits smoke into the environment. corporate social responsibility movement (csrm), a local environmental ngo, filed a writ against tema oil refinery (tor) in the tema high court in 2007 for purportedly contaminating the lagoon with oil and industrial wastewater from their plant [17]. previous studies of lagoon pollution in ghana primarily focus on polycyclic aromatic hydrocarbon pollution [18] and urban waste pollution owusu boadi and kuitunen [19]. biney [15] conducted water quality studies of some rivers and lagoons in ghana, including the chemu lagoon. though his investigations identified chemu lagoon as polluted, they did not consider the relevance of citizen science, what the locals perceived of the pollution and its impacts on their life. apart from this, it is worth conducting a water quality assessment of the lagoon in recent times to mark monitoring lenses on the trends in the lagoon's pollution levels. the research will assist in deciphering why the unregulated disposal and dumping of garbage into the lagoon is exacerbating a decline in the biodiversity population in the area being studied. the research will also function as a position paper for the authorities and other intergovernmental organisations on concerns about monitoring the lagoon. the study positions that if the management policies and recommendations are followed, they will aid in the restoration of the ecosystem to a better state. the locals' income will recover if livelihood is eventually recovered in the lagoon and its watershed. ultimately, the research will add to the existing knowledge on biodiversity protection. this paper assesses the water quality concentration of the chemu lagoon, investigates how the local people perceive the pollution of the lagoon, and analyses the effects of the pollution on the people. asian review of environmental and earth sciences, 2023, 10(1): 28-39 30 © 2023 by the authors; licensee asian online journal publishing group 2. water pollution in ghana water contamination challenges in ghana are inextricably linked to the country's social, economic, and urban growth programs since independence in 1957. following independence, most industry segments were founded throughout the country to promote the natural environment. while leveraging mineral deposits and agricultural operations in industrialisation programs, residents did not take adequate precautions to protect against the environmental cost of these programs and resource depletion [20]. consequently, many ecological concerns are currently faced, including varying air, water, and soil pollution. the mining, mineral exploitation and processing, textile, food processing, and petroleum refining and processing factories substantially contributed to the nation's pollution. most of ghana's industrial establishments are concentrated in the accra and tema metropolitan areas, which account for less than 1% of the country's total land area. the accumulation of these industrial sectors has also resulted in increased sound, fumes, and carbon monoxide emissions, as well as urban and industrial effluents [21]. most liquid waste from manufacturing sectors is expelled into bodies of water unmanaged. as a result, the surroundings have been devastated. the country's manufacturers also induce different types of municipal solid waste. food processing industries, for example, produce organic solid waste; building and construction industries have metal scraps, dust particles, and asbestos tailings; textile and garment industries produce wax, cotton fluff, feints offcuts, and floor wastes. paper cuttings, trimmings, and exposed photo and video films are produced by the paper and printing industries. metal and metallurgical factories produce ferrous, non-ferrous metal, and other wastes [21]. the ghanaian government, environmental regulatory bodies, and social organisations are all collaborating to address the country's ecological problem. among the initiatives that are currently being implemented are: • the formation of the ministry of local government, rural development, and environment to provide policy recommendations [21]. • in 1974, the environmental protection council, known as the environmental protection agency, was established as the primary body to guide and regulate environmental standards. • development and implementation of the national environmental policy (nep) and the national environmental action plan (neap) [21]. all these measures, policies and strategies are perfect on paper, but they have failed to make significant progress in reducing the menace. most of them are either poorly implemented or not enforced due to inadequate resources, corruption and lack of commitment to achieve a sustainable environment. 3. materials and methods 3.1. study area chemu lagoon is situated to the east of tema community 1, as depicted in figure 1. the lagoon is geographically marked within latitudes 5°38'59.09"n and 5°38'38.26"n and longitudes 0°0'45.95"e and 0°1'19.09"e. tema is a coastal city located 25 kilometres east of ghana's capital, accra and has an area of approximately 26 km2. it is differentiated by myriad small streams that connect a mainstream. tema is not only ghana's economic hub but also the location of the state's major main port and one of the most efficient shipping locations on africa's west coast. "over 250 factories in the lagoon catchment, engaged in eight major areas: chemicals, textiles, food processing, engineering, paint, fish cold stores, printing and wood works" [22]. this notwithstanding, the livelihoods of many of the people in the area still revolve around agriculture. like other coastal towns, fishing is the predominant agricultural activity around. however, few people are involved in crop farming activities, including exotic vegetables and fruits [22]. figure 1. map showing the study area in the regional context. source: fieldwork, (2021). 3.2. sampling, data collection, and analysis a two-pronged approach was applied in this study. firstly, concentration analysis of sample water collected from five diverse lagoon points figure 2 was used to assess the lagoon's composition and level of contamination. secondly, the paper employed a descriptive survey design (comprising a structured questionnaire) to evaluate the opinion of the local people on the effects of pollution. asian review of environmental and earth sciences, 2023, 10(1): 28-39 31 © 2023 by the authors; licensee asian online journal publishing group water samples were collected from the lagoon to assess the level of contamination of the chemu lagoon. five sampling points were determined after [23]. the samples were collected and stored in a high-density polyethene bottle. all plastic bottles for sampling were immersed in a 10% hno3 solution for 48 hours and were thoroughly rinsed with double-distilled water before use. the bottles were also washed with water to be sampled at each sampling point to limit contaminants. all water samples were taken at the subsurface to avoid the superficial colloidal layer, which might influence the concentration of specific parameters. samples were put in ice chests with ice cubes to slow biological and chemical reactions and were transported to the water research institute's (wri) laboratory for analysis. water samples from the chemu lagoon were analysed using an atomic absorption spectrophotometer. figure 2. water sample sites along the course of chemu lagoon. source: fieldwork, (2021). moreover, a descriptive survey design was used because the study sought to observe, describe, and record elements of events that take place inevitably or as a consequence of human intervention. according to fraenkel and wallen [24] descriptive research is gathering evidence to address research questions about the current state of a subject of investigation. gay [25] further defined the phenomenological method as appropriate for environmental concerns exploration, appraisal or examination of behaviours, viewpoints, sociodemographic characteristics, constraints, and processes. in light of this, the descriptive survey was selected as the study's design. the estimated population of the age bracket 20 to 60 at tema community one is 18,483, according to the ghana statistical service [26] report, at a growth rate of 2.6% per annum. the sample size was determined following [27], who proposed that a sample size of 377 is ideal for a population of about 20000 persons. the study sampled 377 persons chosen purposively and was in the position to provide relevant information for the analysis. the study thus sampled adults between the ages of 20 years and 60 years old who had lived in the area for at least ten years. this sample was considered appropriate and representative of the current study. the study's instruments featured a structured questionnaire, an interview guide, and an observation schedule. the data were processed and analysed using statistical package for the social sciences (spss) version 23. descriptive statistics and inferential statistics were employed to present the data. the authors used descriptive statistics employing means of concentrations to show the research results. inferential statistics employed paired sample t-tests to establish seasonal differences. the chemical analysis outcomes contrasted the standards for water bodies outlined by the usepa. although it may appear arbitrary to compare facts and social rules independently of date and utilisation, this was done by using the concentrations for studied parameters as the basis for comparison to establish the extent of pollution that the chemu lagoon has been experiencing for many years. 4. results 4.1. respondent's sociodemographic characteristics the socio-economic characteristics of the surveyed residents are presented in table 1. the distribution by gender was 64% males and 36% females. with marital status, 66% of the respondents were married, 28% were single, and 6% were divorced. results on educational attainment found that respondents with no formal education constituted 90 (24%), and formal education in the form of basic, middle, senior high school and tertiary represented 287(76%). this shows that most of the respondents at least have tasted formal education and could have more profound knowledge and appreciation of water pollution issues in the area studied. it is believed that the level of education usually affects the littering behaviour of people. the reported age category of the respondents followed the dimension 21-30 age bracket representing 25%, 31-30 were 33%, 41-50 were 22%, with the least designated age category being those between over 60 years who made 5% of the total respondents. regarding years of stay in the catchment area, the results indicated that 13% of respondents had stayed there for between 1-5 years. another 6 -10 years recorded 18.5%, with 11-15 years recording 21% of the respondents, whilst those who had lived in the area for over twenty years constituted 26%. the data presented in table 1 showed that most respondents have stayed for a long time and are privy to the environmental injustices that have been at play in and around the lagoon. the study found that 43% of the residents earn up to 500 cedis per month. earnings between 501 and 1000 cedis are for about 98 (26%), with another 117 (31%) making over 1000 cedis on average per month. to understand the incidence of waste generation from the household level, the researchers analysed data on the household size of the respondents. the data revealed that households with 2-5 persons comprised 55% of the asian review of environmental and earth sciences, 2023, 10(1): 28-39 32 © 2023 by the authors; licensee asian online journal publishing group respondents, and households with more than 10 constituted 11.5%—persons living alone in a family consisting of 23% of the resident respondents. table 1. socio-demographics characteristics of respondents. variable item frequency percentage gender male 241 64 female 136 36 marital status single 106 28 married 249 66 divorced 23 6 age 21 30 years 94 25 31 40 years 124 33 41 50 years 83 22 51 60 years 57 15 above 60 years 19 5 level of education no formal education 90 24 formal education 287 76 years of residence 1 5 years 49 13 6 -10 years 70 18.5 11 15 years 79 21 16 20 years 81 21.5 over 20 years 98 26 mean monthly income up to 500 cedis 162 43 501 – 1000 98 26 over 1000 cedis 117 31 household size 1 person 87 23 2 -5 persons 207 55 6 10 persons 40 10.5 more than 10 persons 43 11.5 total 377 100 note: source: 1 cedis is equivalent to the average of 5.74 dollars in 2021. fieldwork, (2021). 4.2. seasonal concentrations of parameters as shown in table 2, the chemical analysis results express the status of physico-chemical and heavy metals concentration of the increasingly degrading chemu lagoon. the table shows the concentrations (mg/l) of the physico-chemical and heavy metals parameters in water samples during the wet and dry seasons by their mean concentrations and standard deviations. the table also compares the averages for concentrations with the usepa permissible limits for the water body. table 2 shows the concentration of the parameters analysed during both the wet and dry seasons. as shown, the mean ph for the dry season exceeds the permissible limit according to the usepa standards, while that for the wet season was found to be acceptable. the study also identifies that the mean concentrations or levels of turbidity, temperature, sulphate, phosphates, faecal coliforms, biological oxygen demand, zinc, manganese, lead, and cadmium exceed the usepa limit for water bodies during either season. this expresses that the chemu lagoon is polluted to the extent of the concentrations identified and presented in table 2. the parameters that were below the acceptable level include ammonia and dissolved solids. in the case of ammonia, the acceptable level is 10 mg/l, but the values for the five sites were below the acceptable level; 1.82, 6.21, 2.11, 3.14 and 1.81 mg/l, respectively. according to de lacerda [28], findings identify input pathways, including river-fed pollution, the atmosphere, and direct effluents, which are all at play in the chemu lagoon's catchment. there is a significant distinction between what should be considered the optimal range and the precise thresholds based on the comparisons made between the samples collected and pre-established permissible limits for the quality of water bodies laid down by the environmental protection agency of the united states. it is a clear indication that the lagoon is polluted. activities of the local people and the activities of the industries surrounding the lagoon attribute the higher pollution levels of the lagoon. 4.3. seasonal differences in the concentrations of parameters paired-sample t-test was conducted to explore the differences between the concentrations for parameters for the wet and dry seasons. the results of the paired-sample t-test have been presented in table 3. as shown in the table, the study has established that no statistically significant differences exist between the wet and the dry seasons' concentrations or levels of salinity, conductivity, temperature, total dissolved solids (tds), sulphates, phosphates, potassium, bod, total cyanide, lead, total cadmium, and mercury. for the ph, the study found a significant increase (t (4) = -3.434; p = 0.026) in the level of the measure of acidity or alkalinity from the wet season (mean concentration [m] = 8.9; standard deviation [sd] = 0.48) to the dry season (m = 9.46; sd = 0.46). a significant effect size expressed by an eta-squared statistic of 0.75 is established for the seasonal differences in ph in the chemu lagoon. the results for turbidity found that the passage of time underscores differences in seasons' turbidity observations between the wet and dry seasons. where a significant seasonal variation (t (4) = -3.062; p = 0.038) marked with an eta squared statistic of 0.7, signifying a large effect size between the wet season (m = 47.4; sd = 18.32) and the dry season (m = 61.4, sd = 9.84). the paired-sample difference in the ammonia concentration found a t (4) = -3.048; p = 0.038 with an eta squared of 0.7, connoting a large effect size. for faecal coliforms, the study has found a statistically significant increase (t (4) = -2.834; p = 0.047) in concentrations with the change from wet (m = 1905.2; sd = 645.23) to the dry (m = 2545.6; sd = 779.4) seasons. asian review of environmental and earth sciences, 2023, 10(1): 28-39 33 © 2023 by the authors; licensee asian online journal publishing group table 2. means of seasonal concentrations of parameters. parameter wet season mean sd dry season mean sd usepa limit ph 8.9 0.48 9.46* 0.46 6.5 to 9 salinity 1.7 1.29 0.95 1.27 conductivity 5.28 3.87 7.52 12.7 turbidity 47.4* 18.3 61.4* 9.84 < 0.2 nephelometric turbidity unit (ntu) temperature 32.7* 3.37 33.0* 1.24 < 25oc tds 382 153 342 114 500mg/l (500ppm). ammonia 3 1.87 4.74 2.32 50 mg/l sulphates 897* 317 838* 355 250 mg/l phosphates 2.22* 1.28 2.37* 1.40 0.05 mg/l faecal coliforms 1905* 645 2545* 779 200 colony forming unit (cfu) per 100 ml potassium 7.30 2.29 7.76 2.45 chromium 2.41 1.05 0.14 0.09 0.1 mg/l bilogical oxygen demand (bod) 576* 448 602* 457 50 – 200 mg/l nickel 8.38 0.42 9.57 0.46 0.1 mg/l zinc 17.4* 0.66 23.3* 1.66 5 mg/l iron 22.9 0.95 26.6 1.75 0.3 mg/l benzene 36.4 11.0 46.8 13.5 0.2 mg/l manganese 0.72* 0.23 1.3* 0.1 0.5 mg/l total cyanide 1.08 0.93 1.06 0.54 0.2 mg/l total arsenic 0.88 0.7 1.14 0.91 0.01 mg/l lead 0.48* 0.34 0.65* 0.17 0.05 mg/l total cadmium 0.05* 0.02 0.32* 0.23 0.003 mg/l mercury 0.03 0.01 0.03 0.02 0.002 mg/l note: *exceed permissible limit. source: fieldwork, (2021). table 3. paired-sample differences in parameters' concentrations. pair (wet season – dry season) mean difference t sig. eta squared ph -0.56 -3.43 0.03* 0.75 salinity 0.75 1.29 0.26 0.29 conductivity -2.24 -0.55 0.61 0.07 turbidity -14.0 -3.06 0.03* 0.70 temperature -0.32 -0.23 0.83 0.01 tds 39.6 1.56 0.19 0.38 ammonia -1.79 -3.05 0.03* 0.70 sulphates 58.4 1.21 0.29 0.27 phosphates -0.15 -0.74 0.50 0.12 faecal coliforms -640.4 -2.83 0.04* 0.67 potassium -0.46 -1.12 0.32 0.24 chromium 2.27 4.78 0.00* 0.85 bod -26.0 -0.59 0.58 0.08 nickel -1.18 -4.34 0.01* 0.83 zinc -5.92 -10.6 0.00* 0.97 iron -3.69 -5.49 0.00* 0.88 benzene -10.4 -2.97 0.04* 0.69 manganese -0.58 -4.96 0.00* 0.86 total cyanide 0.02 0.09 0.93 0.00 total arsenic -0.26 -2.15 0.09* 0.54 lead -0.17 -1.94 0.12 0.48 total cadmium -0.27 -2.54 0.06 0.62 mercury -0.005 -0.58 0.59 0.08 note: * connotes a p-value is less than 0.05, which expresses a statistically significant difference in the respective parameter. source: fieldwork: (2021). an eta stared statistic of 0.67, expressing a large effect size, has been established for the seasonal differences in faecal coliforms. the only parameter to observe a decrease in concentrations as a response to seasonal change from the wet (m = 2.41; sd = 1.05) to the dry (m = 0.14; sd = 0.09) seasons. chromium concentrations for either season are significantly varied (t (4) = 4.779; p = 0.009), with a large effect size (eta squared statistic = 0.85). for nickel, zinc, iron, benzene and manganese, the study established increases in their concentrations, which are also not confirmed by chance. finding the most significant effect size (eta = 0.97) among all the differences shown, the case for zinc expresses a mean difference of -5.92 for a t (4) = -10.592; p = 0.000). the wet season concentration for nickel (m = 8.38; sd = 0.42) significantly increased following the passage of time, where a mean zinc concentration of 9.51 and a standard deviation of 0.46 was found for the dry season. the cases for iron, benzene, and manganese found tvalues of t (4) = -5.49, p = 0.005; t (4) = -2.97, p = 0.041; and t (4) = -4.961, p = 0.008, with eta squared statistics of 0.88, 0.69, and 0.86, which all indicate large effect sizes respectively for the seasonal differences in iron, benzene, and manganese. total arsenic, the study also found a large effect size (eta square = 0.54) for the seasonal difference in the concentrations. this effect size is the least identified among the studied parameters. despite this, a mean difference of -0.26 has been found for a t (4) = -2.152, p = 0.098 to express seasonal increase in total arsenic concentrations. 4.4. residents' perception of the status of the chemu lagoon the results from the study indicate that the residents are much aware of the pollution of the water body. about asian review of environmental and earth sciences, 2023, 10(1): 28-39 34 © 2023 by the authors; licensee asian online journal publishing group 92% said the lagoon is polluted, while only 8% believed it is not contaminated table 4. the level of perception of the residents may go a long way to finding a lasting solution to the problems confronting them since they are aware of the extent of the problem and may advocate for alleviating the pain. table 4. rating of perception by residents. lagoon status indicator n statistic mean statistic sd statistic skewness kurtosis statistic s. e statistic s. e low fish catch 200 4.76 0.43 -1.23 0.17 -0.50 0.34 odour in the community 200 4.71 0.61 -1.95 0.17 2.49 0.34 poor water quality 200 4.61 0.62 -1.34 0.17 0.70 0.34 extinction of fish 200 4.76 0.43 -1.23 0.17 -0.50 0.34 extinction of native vegetation 200 4.56 0.64 -1.16 0.17 0.22 0.34 depth of lagoon 200 4.65 0.66 -1.65 0.17 1.33 0.34 colour of lagoon water 200 4.65 0.50 -0.90 0.17 -0.60 0.34 waste deposition by industries 200 4.86 0.35 -2.09 0.17 2.40 0.34 note: 1 = strongly disagree, 2 = disagree, 3 = don't know, 4 = agree, 5 = strongly disagree. source: fieldwork: (2021). to further interrogated the respondents on their perceptions of the chemu lagoon. a likert scale was developed to solicit their views on some variables. table 4 presents the views expressed by the respondents. the first variable was waste deposition by nearby industries into the lagoon. waste deposition by nearby enterprises was considered the most dominant variable affecting the lagoon, with mean = 4.86 (sd = 0.35), which attests to the respondents' strong agreement with the position that waste deposition by industries induces pollution of the lagoon. to establish that there has been a change in the quality of the chemu lagoon, the study sought to evaluate the respondents' perception of the lagoon's odour. the study found a mean of 4.71, with a standard deviation of 0.61, indicating that respondents strongly agree that the lagoon brings forth offensive odour around the local communities. in analysing the ability of the lagoon to support aquatic life, the study found that some fish species in the lagoon have gone extinct. the study found a mean of 4.76 with a standard deviation of 0.43 to establish the case. to the same degree, this translates into an expression that there has been a decline in the fish catch and, consequently, lower economic returns. this backs up [29] claim that a wide range of substances such as oil, gasoline, plastics, pesticides, cleaning detergents, and solvents can endanger public health and fish and other aquatic organisms. the study also has established that the chemu lagoon has assumed shallowness as the results express a mean of 4.65 and a standard deviation of 0.65, suggesting that the refuse deposition into the lagoon has resulted in sedimentation, leading to its shallow nature. boateng, et al. [5], as an indication of high eutrophication, also reported the shallowness of lagoons in ghana, predisposing the lagoons to other events such as flooding and an increase in temperature. following the establishment of refuse deposition into the lagoon, the study investigated means of waste disposal in the study area. the survey showed that 62% of respondents either dispose of household waste into refuse containers or have agreed with a waste management entity to collect them whenever their bins are full. the remaining 38 per cent either cast their destruction at the shores of the lagoon or empty them into the drains, which as well have the potential to end up in the immediate lagoon environment. as shown in figure 3, 45%, 34%, 4%, and 17% of residents explicitly expressed that they manage waste by disposing of it in refuse containers, on the lagoon's shores, into drains, and collecting by waste contractors, respectively. restudy positions that it is not automatic that the case expressed here is the reflection of reality since the researchers acknowledge the room for false information shared by respondents concerning their means of waste disposal. other things being equal, though the study's goal was presented to the respondents, some respondents would still share false information for fear of being arrested for disposing of waste in an environmentally unfriendly manner. respondents, however, reported that many people defecate on the lagoon's shores; the faeces eventually end up in the lagoon, and consequently, the higher accumulation of faecal coliforms, especially the higher level in the wet season, and the higher concentration in the dry season. figure 3. disposal of solid waste in the area. source: fieldwork, (2021). again, to further explore the level of awareness, the residents were asked why some of them fly-tip the domestic waste. eighty-six per cent (86%) of the respondents believed that there were inadequate refuse collection points in asian review of environmental and earth sciences, 2023, 10(1): 28-39 35 © 2023 by the authors; licensee asian online journal publishing group the area, with 14.0% saying that refuse collection points in their place were adequate table 5. these results further explain why some residents chose to dispose-off refuse indiscriminately in the study area. figure 4 shows the unsanitary conditions at abonkor, one of the four communities selected for the study. refuse was found at the doorsteps of residents. figure 4. insanitary conditions in a squatter settlement at abonkor. source: ghana business news [30]. 4.5. contribution of socio-economic activities to pollution of the chemu lagoon human activities around the lagoon impinged the environment, affecting flora and fauna. the chemu lagoon, which was once a nesting place for birds and provided boating facilities for tourists, is now polluted and almost empty. according to the study results shown in table 5, 82% of the respondents believed that tourist operations had a detrimental effect on the lagoon. around 18% of those polled were of the opposing opinion. the respondents espoused that the activities of the visitors contribute to waste generation. most visitors deposed items, including polythene bags, empty cans, food items and other waste products along the lagoon, which in the long run, ended up in the lagoon—the result above shows that waste disposal facilities were not adequate. the results attest to the observation by molina and molina [31] that dense concentrations of the population, such as those found in large cities, or are brought together by warfare and trade, tourism, etc., are usually necessary for water-borne diseases to attain epidemic proportions through the accumulation of waste. it is also consistent with the findings of the environmental protection agency [epa] [32], which observed poor domestic sanitary conditions and illegal dumping of metropolitan solid and liquid materials as the primary prevalent challenges facing coastal regions. figure 5. fishing activities in the polluted chemu lagoon. source: fieldwork, (2021). results from the study, table 5, indicate that the respondents were very much aware of the pollution of the lagoon. ninety-two per cent (92%) of the inhabitants were aware of the lagoon being polluted, while only eight per cent (8%) were not of pollution in the lagoon's environment. the results imply that the inhabitants know about the various environmental problems in the area. this supports the view expressed by thorne-miller [33], who posits that people are most of the time aware that, accidentally or deliberately, the substances and materials they release into water bodies act in and on the environment. figure 5 illustrates fishing activities ongoing in the polluted lagoon, though respondents are aware of the lagoon's status as polluted. asian review of environmental and earth sciences, 2023, 10(1): 28-39 36 © 2023 by the authors; licensee asian online journal publishing group figure 6. satellite image of urban growth towards the floodplains of the chemu lagoon. source: google earth (2022). table 5 shows that (96 per cent) of participants believe that the development of squatter settlements has contributed significantly to the contamination of the lagoon. the other 4% disagreed. personal observations by the researchers indicated that in some areas, the growth of slums had led to the discharge of untreated wastes and, consequently, led to the gradual pollution of the wetlands surrounding the lagoon where aquatic life would thrive. an observation of the lagoon shown in the satellite image in figure 6 shows urban growth enclosing the chemu lagoon. surface run-off from point source pollution, such as residential and commercial sewers, can carry harmful emissions like soil particles, pesticides, and fertilisers into coastal wetlands. according to the environmental protection agency [epa] [32], the korle, osu klottey, and kpeshie lagoons in accra and the fosu lagoon in cape coast are all in multiple states of degeneration and environmental damage as a result of the effects of poor residential sanitation. 4.6. health and socio-economic effects of the lagoon pollution results from table 5 indicate that 84% of the respondents believe that people fall sick frequently due to the polluted environment, while 16% shared the opposite view. poor domestic sanitation was the most pervasive of all of the problems found around the lagoon. this environmental problem facilitates the locals' poor health, the lagoon's polluted ecological status, and the unappealing situations that impede economic and social development, such as tourism. mulamoottil [34] stated that unsanitary environments directly or indirectly cause up to 40% of diseases reported at hospitals nearby. table 5. residents' perception of the status of the chemu lagoon. item response frequency percentage awareness of the chemu lagoon pollution yes 347 92 no 30 8 adequacy of refuse collection points in the area yes 53 14 no 324 86 pollution of chemu lagoon by visitors yes 309 82 no 68 18 waste disposal facilities near the lagoon yes 53 14 no 324 86 slums created around the lagoon yes 362 96 no 15 4 effects of pollution on human health yes 317 84 no 60 16 authorities organising meeting on chemu lagoon yes 79 21 no 298 79 figure 7 shows the respondents who attributed the various diseases reported in the study area to pollution. most (64%) respondents attributed the malaria outbreak to pollution. again 25% of them viewed that pollution caused typhoid fever in the area. six and five per cent (6%, & 5%) said pollution caused cholera and abdominal pains in the studied communities. the diseases mentioned above are primarily endemic in polluted and dirty environments where people defecate and dispose of waste indiscriminately. the study confirms the findings of owusu boadi and kuitunen [19] from their survey of the korle lagoon that the presence of water does not always make communities healthier. water carries harmful organisms or germs that cause cholera, typhoid, and diarrhoea. source: fieldwork, (2021). asian review of environmental and earth sciences, 2023, 10(1): 28-39 37 © 2023 by the authors; licensee asian online journal publishing group figure 7. health effects of pollution of the chemu lagoon. source: fieldwork, (2021). 4.7. efforts made by stakeholders to combat pollution of the chemu lagoon though several legislations exist on coastal protection and sustainable management, there was the need to determine whether the community members had taken it upon themselves to protect the lagoon from pollution and extinction. table 6 presents the residents' views on the attendance of the meeting to discuss the lagoon's pollution issue. from table 6, 79% of the respondents said they had not heard about any form of meeting concerning lagoon management. about 21% said they had heard about some meetings. the findings corroborate the environmental protection agency [epa] [21] position that the authorities should enforce environmental stewardship laws in the catchment. the ministry of environment and science and the environmental protection agency (epa) is projected to investigate the ecological consequences of sanitary development initiatives. table 6. institutions that call meetings. agencies frequency percentage assemblyman 21 5.5 chief 15 4.0 ngo’s 43 11.5 tma 298 79.0 total 377 100 source: fieldwork, (2021). when asked if there were institutions that organised meetings on the lagoon's pollution, 79% of the respondents said the tema metropolitan authority (tma) organises such conferences. others (about 12%) said that some nongovernmental organisations (ngos) do that, while 21 respondents mentioned that the assembly members of the study areas do that, as presented in table 6. these results indicate that the lagoon's mandate on protection and sustainability is virtually in the hands of tma and the ngos. consequently, the tma must embark on serious health education in the communities. the data reinforce the environmental protection agency [epa] [32] assertion that ghana has a diverse range of non-governmental organisations and neighbourhood entities dedicated to environmental preservation and enhancement. the chiefs and assembly members of the selected communities are responsible for protecting and regulating the residents' activities. still, their efforts (to preserve the lagoon) often meet challenges, including opposition from the community members who depended on the lagoon for their livelihoods. when the respondents were asked if the authorities act to protect the lagoon from pollution, 67% said that the leaders were helping in discussions to address the pollution problems and to stop the indiscriminate disposal of waste. in comparison, 33% said no authority helped. 5. discussions the pollution issue of ghana's coastal lagoons was identified decades ago [6]. admittedly, nothing has changed to this day. according to the ipcc [35]; ipcc [36], releasing untreated sewage, manufacturing, and agricultural residues contaminates most coastal lagoons in west africa, including ghana. urbanisation, industrialisation, population pressures and poor waste management systems commonly cause pollution. the pollution has adversely affected the ecosystem services of the lagoons, particularly fisheries resources and migratory birds from europe [3, 37]. the results from the water quality analysis of the chemu lagoon showed that turbidity, temperature, sulphate, phosphates, faecal coliforms, biological oxygen demand, zinc, manganese, lead, and cadmium exceeds the usepa's permissible limits. this finding is in line with adu-boahen and boateng [23] studies on the fosu lagoon in ghana that revealed higher concentrations of like parameters. similar results were recorded by biney [15] in the chemu lagoon. biney [15] found that the surface water temperature of the lagoon ranged between 22oc and 36oc and attributed higher water temperature to the thermal pollution originating from industrial sources. the implication is asian review of environmental and earth sciences, 2023, 10(1): 28-39 38 © 2023 by the authors; licensee asian online journal publishing group that knowledge about pollution was known to the residents, but no significant improvement has been achieved over the years. the results stand with the position of koledoye, et al. [38], who found in their study on the lekki lagoon that anthropogenic activities have latent health and environmental impacts that have prognosticated grave concern if not urgently mitigated. in another study [39] on the muni pomadze and its catchment, it was revealed that most of the physico-chemical properties studied, temperature, tds, conductivity, ph, salinity, and dissolved oxygen (do) were within the acceptable limit of usepa for freshwater resources. according to molina and molina [31] the head of the epa in tema, mr lambert faabeluon, told the daily graphic that the institution and other interested parties had held a total of 12 symposiums and consultations since 1999 to probe strategies for preventing further harmful discharges into the chemu lagoon, and to mobilise resources for the resuscitating the lagoon. notwithstanding, hardly anything significant had come from the countless seminars and meetings held by relevant parties since 1999. the failure to progress on recovery and the lagoon's continued contamination is due to an absence of dedication by crucial parties to adopt measures and initiatives that will cease environmental damage and re-establish the lagoon. despite citizen science identifying that the residents are not naïve to the deteriorating quality of the lagoon, the people who, for that matter, would be interested in the welfare of the lagoon are culprits themselves, as they also contribute to the pollution of the lagoon. about 34% figure 3 indicated that they dispose of the refuse in the lagoon and its environs. this put the residents in a compromising situation to demand changes. the local authority contributes to the problem by not providing adequate waste deposal facilities table 5, thus forcing the residents to contribute to the pollution so that they cannot demand change because they are offenders. this explains the reason the majority of the residents were aware of the extent of the pollution and its effects on health and socio-economic activities table 5. yet, they have failed to be the champions of change regarding the lagoon's pollution. the survey results from table 6 indicate that the effort by the residents to restore the lagoon is about 10%. it is tma and ngos that have made the most effort. the most action should have come from the residents since they suffer from the immense pollution of the lagoon. because the former administration by tma and ngos did not produce the desired results, it is required to empower residents to direct the campaign for the rehabilitation of the chemu lagoon. there is a need to bring all stakeholders on board in a participatory manner under the residents' leadership to develop the chemu lagoon restoration plan. such a plan will not be viewed as the traditional top-down government policy; all the participating stakeholders will own it. such ownership by the stakeholders will facilitate the successful implementation of the plan. regardless of the apparent connection between contamination and the development of fishery ecosystems (types of fish) and other economic interests from the chemu lagoon, there were insufficient patterns and attitudes on the degree of the environmental damage as well as the clear implications on local people's well-being and socio-economic existence. this paper has provided the baseline information required for action on developing a management strategy and committing to applying the existing environmental laws and policies in ghana. the environment cannot be limited by national territorial boundaries [40]. migratory birds that feed on the lagoon habitat could extend the impact of the pollution beyond tema and its environs. therefore, national, regional and international environmental pressure groups must join the call to restore chemu and other polluted lagoons in ghana. the following recommendations are made in light of the findings: • the environmental health department and the waste management department of the tema metropolitan assembly are advised to intensify their house-to-house hygiene education and inspections in the catchment area on proper waste disposal to prevent indiscriminate defecation and flying tipping. • the effective use of the limited facilities located along the stretch of the lagoon should be addressed. the assembly should increase the number of waste and sanitary facilities in the catchment area. • the sanitation task force of the tema metropolitan assembly should check the activities of the local people which pollute the lagoon. • offenders found of indiscriminate defecation and dumping of refuse should be arrested and prosecuted to serve as a deterrent. • the assembly should stop further slum creations and demolish the existing ones in the catchment area. • residents, the tema metropolitan assembly, the tema traditional council, local industries, and the central government should work together to replenish the lagoon to its natural form. the collaborative efforts would strengthen the socio-economic status functions of the residents. the assembly should prioritise the area's development into parks and gardens to assist in restoring the polluted ecosystems. 6. conclusions the outcomes of water quality analyses using water samples from chemu lagoons were significantly higher than the usepa-recommended thresholds. this could be related to the lagoons being used as dumping grounds by most residents and the release of industrial emissions into the lagoons. almost all the water quality parameters measured had higher values in the dry season than in the wet season. these results could be due to the evaporation of water from the lagoons' interface during the dry season, which resulted in higher concentrations in the lagoons. the level of siltation and the dumping of refuse into the lagoon hampers the free flow of water and hence encourage mosquito breeding of mosquitoes and the incidence of high malaria outbreak and other related diseases affecting the health and socio-economic lives of the people. the study concludes for informed resuscitation of the lagoon and the preservation of its ecological services, the data from this study, combined with future data, may help to monitor the chemu lagoon. the various stakeholders are not doing enough to help combat the pollution problems in the area. it is worth noting that most respondents are unaware of any environmental law on the dumping of waste or the activities of groups forming slums along the lagoon and their further pollution. insufficient sanitary facilities have led to indiscriminate solid waste disposal and defecation at the lagoon's banks. references [1] h. m. conesa and f. j. jiménez-cárceles, "the mar menor lagoon (se spain): a singular natural ecosystem threatened by human activities," marine pollution bulletin, vol. 54, no. 7, pp. 839-849, 2007. https://doi.org/10.1016/j.marpolbul.2007.05.007. https://doi.org/10.1016/j.marpolbul.2007.05.007 asian review of environmental and earth sciences, 2023, 10(1): 28-39 39 © 2023 by the authors; licensee asian online journal publishing group [2] b. kjerfve, coastal lagoon processes. amsterdam, the netherlands: elsevier, 1994. [3] m. entsua-mensa, "the contribution of coastal lagoons to the continental shelf ecosystem of ghana. the gulf of guinea large marine ecosystem," elsevier. science b.v, vol. 11, pp. 161-169, 2002. https://doi.org/10.1016/s1570-0461(02)80035-0. [4] n. t. odjer-bio, e. j. belford, and m. ansong, "what is happening to our lagoons? the example of butuah lagoon in ghana," international journal of energy and environmental engineering, vol. 6, no. 2, pp. 183-193, 2015. https://doi.org/10.1007/s40095-0150165-1. [5] i. boateng, s. mitchell, f. couceiro, and p. failler, "an investigation into the impacts of climate change on anthropogenic polluted coastal lagoons in ghana," coastal management, vol. 48, no. 6, pp. 601-622, 2020. https://doi.org/10.1080/08920753.2020.1803565. [6] united nations world water assessment programme [un wwap], the world water development report 1: water for people, water for life. paris: unesco, 2003. [7] united nations world water assessment programme [un wwap], "world water assessment programme," the united nations world water development report 3, water in a changing world, 2009. [8] l. florencio, m. t. kato, and e. s. de lima, "integrated measures for preservation, restoration and improvement of the environmental conditions of the lagoon olho d'agua basin," environment international, vol. 26, no. 7-8, pp. 551-555, 2001. https://doi.org/10.1016/s0160-4120(01)00038-1. [9] m. kwadzo, m. k. miyittah, d. b. dovie, r. k. kosivi, and r. owusu, "pollution and climate change impacts on livelihood outcomes of lagoon fishermen in central region, ghana," current research in environmental sustainability, vol. 4, p. 100137, 2022. https://doi.org/10.1016/j.crsust.2022.100137. [10] s. prakash et al., "potential of ecotourism development in the lake bosumtwi basin: a case study of ankaase in the amansie east district, ghana," working paper no. 15, socio-economics of forest use in the tropics and subtropics, university of freiburg, germany, prentice –hall, press, 2005. [11] united nations children's fund, "unicef handbook on water quality," waterlines, vol. 13, pp. 8-10, 2008. [12] world health organization, guidelines for drinking-water quality: second addendum. vol. 1, recommendations. geneva: world health organization, 2008. [13] fao, "the world's mangroves 1980-2005," fao forestry paper no. 153, 2007. [14] p. k. acheampong, themes and earth. cape coast: university press, university of cape coast, 2009. [15] c. a. biney, "preliminary survey of the state of pollution of the coastal environment of ghana," oceanology minutes, no. sp, pp. 39– 43, 1982. [16] n. k. o. anny, "chemu lagoon, an end in sight?," retrieved: http://www.ghanaweb.com/ghanahomepage/newsarchive/artikel.php?id=120267. [accessed 2007. [17] myjoyonline.com, "tor sued for pollution," retrieved: https://www.myjoyonline.com/tor-sued-for-pollution/. [accessed january 11, 2023], 2007. [18] d. essumang, c. adokoh, j. afriyie, and e. mensah, "source assessment and analysis of polycyclic aromatic hydrocarbon (pah's) in the oblogo waste disposal sites and some water bodies in and around the accra metropolis of ghana," journal of water resource and protection, vol. 1, no. 6, pp. 456-468, 2009. https://doi.org/10.4236/jwarp.2009.16055. [19] k. owusu boadi and m. kuitunen, "urban waste pollution in the korle lagoon, accra, ghana," environmentalist, vol. 22, no. 4, pp. 301-309, 2002. [20] environmental protection agency [epa], environmental policy on pollution in ghana. ghana: environmental protection agency, 1991. [21] environmental protection agency [epa], "ghana environmental resource management project," development options for coastal wetlands, final report no. 1 & 2, 1994. [22] ghana districts, "metropolitan theme assemby," retrieved: https://www.ghanadistricts.com/home/district/118. [accessed 2012. [23] k. adu-boahen and i. boateng, "mapping seasonal variation in the distribution and concentration of heavy metals using water quality index and geographic information system based applications," journal of geographical research, vol. 4, no. 2, pp. 31-42, 2021. https://doi.org/10.30564/jgr.v4i2.3100. [24] j. r. fraenkel and n. e. wallen, how to design and evaluate research in education, 4th ed. boston: ma, mcgraw-hill, 2000. [25] r. l. gay, educational research: competencies for analysis and application, 4th ed. new york: merrill/macmillan, 1992. [26] ghana statistical service, "metropolitan theme assembly," retrieved: https://www2.statsghana.gov.gh/docfiles/2010_district_report/greater%20accra/tema%20metro.pdf. [accessed 2010. [27] r. v. krejcie and d. w. morgan, "determining sample size for research activities," educational and psychological measurement, vol. 30, no. 3, pp. 607-610, 1970. https://doi.org/10.1177/001316447003000308. [28] l. d. de lacerda, "biogeochemistry of heavy metals in coastal lagoons," elsevier oceanography series, vol. 60, pp. 221-241, 1994. https://doi.org/10.1016/s0422-9894(08)70013-8. [29] p. a. g. m. scheren, "integrated water pollution assessment in dataand resource-poor situations: lake victoria and gulf of guinea case studies," phd thesis, eindhoven university of technology, the netherlands, 2003. [30] ghana business news, "gpha to dredge heavily polluted chemu lagoon at the cost of over gh¢7.5m," retrieved: https://www.ghanabusinessnews.com/2019/12/06/gpha-to-dredge-heavily-polluted-chemu-lagoon-at-cost-of-over-gh%c2%a275m/. [accessed 1 september 2022, 2019], 2019. [31] m. j. molina and l. t. molina, "megacities and atmospheric pollution," journal of the air & waste management association, vol. 54, no. 6, pp. 644-680, 2004. [32] environmental protection agency [epa], state of environment report 2001. accra: environmental protection agency, 2004. [33] b. thorne-miller, the living ocean: understanding and protecting marine biodiversity. washington, d.c: island press, 1999. [34] g. mulamoottil, "indigenous institutions and environmental assessment: the case of ghana," environmental management, vol. 21, no. 2, pp. 159-171, 1997. https://doi.org/10.1007/s002679900015. [35] ipcc, climate change 2007, impacts, adaptation and vulnerability: contribution of working group ii to the fourth assessment report of the ipcc. cambridge: cambridge university press, 2007. [36] ipcc, climate change 2014: impacts, adaptation, and vulnerability. part b: regional aspects. contribution of working group ii to the fifth assessment report of the intergovernmental panel on climate change, in v. r. barros, c. b. field, d. j. dokken, m. d. mastrandrea, k. j. mach, 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. cambridge, united kingdom and new york, usa: cambridge university press, 2014. [37] y. ntiamoa-baidu, "conservation of coastal lagoons in ghana: the traditional approach," landscape and urban planning, vol. 20, no. 1-3, pp. 41-46, 1991. https://doi.org/10.1016/0169-2046(91)90089-5. [38] t. koledoye, b. akinsanya, k. adekoya, and p. isibor, "physicochemical parameters of the lekki lagoon in relation to abundance of wenyonia sp woodland, 1923 (cestoda: caryophyllidae) in synodontis clarias (linnaeus, 1758)," environmental challenges, vol. 7, p. 100453, 2022. https://doi.org/10.1016/j.envc.2022.100453. [39] n. y. boanu, i. y. dadson, k. adu-boahen, and e. o. yeboah, "assessment of the physico-chemical properties in the muni-pomadze ramsar site and its catchment in winneba, ghana," environmental protection research, vol. 2, no. 2, pp. 95-111, 2022. https://doi.org/10.37256/epr.222022786. [40] m. s. islam and m. tanaka, "impacts of pollution on coastal and marine ecosystems including coastal and marine fisheries and approach for management: a review and synthesis," marine pollution bulletin, vol. 48, no. 7-8, pp. 624-649, 2004. https://doi.org/10.1016/j.marpolbul.2003.12.004. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://doi.org/10.1016/s1570-0461(02)80035-0 https://doi.org/10.1007/s40095-015-0165-1 https://doi.org/10.1007/s40095-015-0165-1 https://doi.org/10.1080/08920753.2020.1803565 https://doi.org/10.1016/s0160-4120(01)00038-1 https://doi.org/10.1016/j.crsust.2022.100137 http://www.ghanaweb.com/ghanahomepage/newsarchive/artikel.php?id=120267 https://www.myjoyonline.com/tor-sued-for-pollution/ https://doi.org/10.4236/jwarp.2009.16055 https://www.ghanadistricts.com/home/district/118 https://doi.org/10.30564/jgr.v4i2.3100 https://www2.statsghana.gov.gh/docfiles/2010_district_report/greater%20accra/tema%20metro.pdf https://doi.org/10.1177/001316447003000308 https://doi.org/10.1016/s0422-9894(08)70013-8 https://www.ghanabusinessnews.com/2019/12/06/gpha-to-dredge-heavily-polluted-chemu-lagoon-at-cost-of-over-gh%c2%a27-5m/ https://www.ghanabusinessnews.com/2019/12/06/gpha-to-dredge-heavily-polluted-chemu-lagoon-at-cost-of-over-gh%c2%a27-5m/ https://doi.org/10.1007/s002679900015 https://doi.org/10.1016/0169-2046(91)90089-5 https://doi.org/10.1016/j.envc.2022.100453 https://doi.org/10.37256/epr.222022786 https://doi.org/10.1016/j.marpolbul.2003.12.004 9 © 2022 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 9, no. 1, 9-17, 2022 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v9i1.4070 © 2022 by the authors; licensee asian online journal publishing group prediction of the strength behaviour of the sandy soil by using collapse potential in the kintele site-congo adolphe kempena1 gampio urbain mbilou2 dhorjeanny bissombolo3 antonio olimpio goncalves4 florent boudzoumou5 ( corresponding author) 1,2,3,5department of geology, faculty of sciences and techniques, marien ngouabi university, brazzaville, congo. 1email: akempena@gmail.com tel: +242069521826 2email: gampiombilou@gmail.com tel: +242069542043 3email: bissombolodhorjeanny@gmail.com tel: +242064393022 5email: boudzoumouf@gmail.com tel: +242066710201 4department of geology, faculty of sciences, agostinho neto university, luanda, angola. 4email: tonygoncalves72@hotmail.com tel: +244926887944 abstract this work aims to evaluate the water effect on the soils collapse potential. the laboratory tests based on the soils samples preparation determined the soils properties. parameters such as water content, dry unit weight, degree of saturation, voids ratio and particles size distribution were determined. the collapse potential was analysed indirectly according to various researchers criteria. the results confirmed the high vulnerability of the study area to collapse. the oedometer tests determined the values of the collapse potential showing the conventional relationship between the collapse potential and the water content. it is noted that increasing water content leads to decrease soils strength to collapse, and the increasing progress of collapse poses a risk to constructions on silty sand. the collapse potential decreases with the increase in the relative density keeping the water content constant. this collapse potential caused by soil water content variation can be reduced from compaction. keywords: collapsible soils, collapse potential, collapsibility, saturated soil, unsaturated soil, sandy soil, water content. citation | adolphe kempena; gampio urbain mbilou; dhorjeanny bissombolo; antonio olimpio goncalves; florent boudzoumou (2022). prediction of the strength behaviour of the sandy soil by using collapse potential in the kintele site-congo. asian review of environmental and earth sciences, 9(1): 9-17. history: received: 2 may 2022 revised: 5 july 2022 accepted: 18 july 2022 published: 26 july 2022 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 10 2. materials and methods ................................................................................................................................................................... 11 3. results ................................................................................................................................................................................................ 14 4. discussion .......................................................................................................................................................................................... 16 5. conclusions ....................................................................................................................................................................................... 16 references .............................................................................................................................................................................................. 16 mailto:akempena@gmail.com mailto:gampiombilou@gmail.com mailto:bissombolodhorjeanny@gmail.com mailto:boudzoumouf@gmail.com mailto:tonygoncalves72@hotmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v9i1.4070 https://orcid.org/0000-0002-9938-810x asian review of environmental and earth sciences, 2022, 9(1): 9-17 10 © 2022 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this work contributes to solve and to make clear problems related to constructions which are exposed to the risk of collapse. 1. introduction in geology and geotechnical engineering, soil collapse phenomena with a significant percentage of fines induce differential settlements, leading to damage of infrastructures (building, foundations and retaining structures). sudden collapse potential is occurred many times on unsaturated soils with potential deformations and radical rearrangement of grains after wetting. these soils with loose structures are often made of grains ranging from clay to fine sand. they are particularly located in areas with a complex relief. these regions have become vital today, in view of the demographic and technological evolution of the man who exploits his wealth. the occupation of these areas necessarily leads to the modification of their original properties. this favours the ideal environment for soil collapse and consequently the ruin of constructions [1]. many existing researches noticed many unsaturated soil problems confronted by engineers, related to collapsible and expansive soils under wet conditions. from the volume changes, the soils can remain problematic in construction engineering due to their expansion, collapsibility, dispersion, and sometimes excessive settlement with a loss of strength. certain soils behaviours can be referred to their mineralogy, the pore liquids nature, or their particles arrangement. collapsible soils have tendency to collapse as a closely packed, with a significant reduction of their volume. the collapsible soils have a non-significant inter-particle link strength which is destroyed by either soil filling, saturation of soil or a mixture of both conducting to soil collapse occurrence [2]. constructions on collapsible soils are often suffered of unexpected settlements, with tendency to produce awful failure. in general, an inundation of the soils in metastable state causes collapse in loess soil and engorgement for some clayey soils. then, in geotechnical engineering the collapsible soils instability is associated to the effect of water when the soil is under wetting conditions. these types of soils lead to high defies in foundations engineering [3]. collapsible soils have become a grave engineering problem and a geotechnical challenge all over the world. these soils can be formed naturally or by man activity and sometimes represent a natural risk for a man and his property [4]. unexpected collapse happens once wetting or surcharge surpass the yield of the material resistance [5]. collapsible soils are largely formed by silt and fine sandy soils, sometimes with low clay content. the soil can be affected by wetting, such as rainfalls and groundwater level growth, or by man activities. though, collapsible soils are conquered for man activities. many factors can describe the collapse behaviour of soils such as the collapse prediction related to any type of unsaturated soils, the compacted soils with perfect water content; the capillary action in the soils which yields shear stresses; the increasing compressibility that causes a shear strength reduction of soils leading them to failure [6]. studies based on soils collapsibility behaviour consider the collapse potential as an essential monitor for foundations design [6]. the evaluation of soils collapsibility from many criteria has been well-defined by several investigators. research works related to soils collapsibility could be find in existing literatures [7-14]. collapse potential was firstly revealed by jennings and knight [6] and repetitive tests were advanced to measure soil collapse. schwartz [15] systematically revised these works in the art paper state. foundations for collapsible soils have tendency to be predictable when they are built on a collapsible soil layer, excavation and recompaction of the material with drainage safety to avoid inundation process. the works based on the collapsible soils properties deal with the identification, laboratory tests and engineering properties of collapsible soils [16]. collapsible soils could mostly be recognised by using laboratory tests of particles size, atterberg limits, dry density, saturation degree which are able to predict collapse. oedometric or triaxial laboratory tests could determine the collapse potential with some plain restrictions for disturbed soils samples as revealed by houston, et al. [17]. fredlund and gan [18] moved off the collapse relationships by using a similar method to consolidation principle and including suction stresses. lin [19] proposed instructive test outcomes for unsaturated soils highlighting the effect of overload stresses, suction stresses and saturation degree. schwartz [15] evoked that the degree of saturation remained important in evaluating collapse potential, being a degree of saturation at a critical level during the collapse occurrence. inopportunely this perception can be essentially disregarded in practice, while mcknight [20] replicated the schwartz data and additional information, thus made a convenient illustration of an overall relationship among critical saturation degree and percentage of fines. schwartz [15] also considered the effective pressure in the design of any construction structures. compilation delivered by rogers [2] produced the meanings of collapsible soils from many studies such as a soil with a considerable volume variations by wetting, loading, or a mixture of both. any unsaturated soil with particles rearrangement can show significant loss of volume by wetting with or without further loading [14]. there are additional settlements caused by unsaturated soils, without some increase in practical stresses. some existing works are focused on the wetting state of unsaturated soils under consolidation which is associated to apparent cohesion of unsaturated soils. residual soils sometimes involve minerals decomposition from rocks leading the soils willing to collapse. residual soils have greatest high spatial changes, therefore their potential collapse becomes difficult to predict. aeolian soils include dunes and loess found as sandy silt covering abundant of the earth’s surface where alluvial soils and colluvial soils are moved by water or by gravity and may be extremely collapsible [5, 6]. sandy soils cover the northern part of congo republic including the study area. an amount of problems related to these sands were emphasised by existing works [21]. the major geological and geotechnical problem was observed to be the great collapse potential of these sands under different conditions. in this work is founded on soil sampling with laboratory tests to evaluate the collapse phenomena in the study area. then, the selected site represents the northern area of ignie department, congo republic as shown in figure 1. asian review of environmental and earth sciences, 2022, 9(1): 9-17 11 © 2022 by the authors; licensee asian online journal publishing group 2. materials and methods 2.1. study area information about the climate, relief and geology of the study area is vital for the soils engineering properties and it is a pre-requisite for the design of foundations. the study area is located in the northern part of kintele, in southern part of ignie department as can be seen in figure 1. morphologically the study has a flat relief, valleys and hilly areas. the years 80’s were less warm than the years 90’s. two periods plainly characterize the recent evolution of temperatures in congo before 1970 and after. brazzaville presents a net variation of temperature from 1932 to 2010 showing an increase of +0.5˚c to 1˚c as average temperatures in the preceding two decades. but it is noticed the maximum and minimum average temperatures in the 1990s with an increase for the two recent decades. the maximum and minimum altitudes are 1100 m and 360 m respectively. the climate is tropical with a rainy season from october to may, and dry seasons between january-february and june-september. the annual rainfall oscillates among 1250 mm and 1350 mm/year [22]. the hydrogeological group is part of the bateke’s water table, with an area of 270 km2. the aquifer components are sandstone with a weak contribution to the groundwater mineralogy. but two zones are identified using the ca2+/mg2+ ratio. the first zone determines the calcium minerals showing weathering process and the second one with ratio higher of ca2+/mg2+ which shows the dissolution of magnesium [23]. the soils are settled on different materials of three sedimentary series from the base to the top, made of the sandstone series of inkisi, the sandstone series of the stanley pool and the series of bateke’s plateau. the soils are ferrallitic and hydromorphic. in general, these soils have very low clay content [24]. the central basin, involves the intracratonic depression of central africa with accumulation of sediments, tectonic activity and erosion process during a long history. then the geological background consists of a precambrian to paleozoic age formation supporting a mesozoic to cenozoic sedimentary cover that rests unconformably on a precambrian basement. thus, the precambrian to paleozoic basement which appears downstream from the stanley pool and the sedimentary cover is formed by essentially sandy materials which outcrop upstream from the stanley pool series [25]. figure 1. study area. 2.2. methodology the study used terrain data related to geography, geology, superficial water and ground water to pick out soil specimens. the method of pits was selected for this study with four pits excavated followed by soils samples collection where, different laboratory tests were performed. the collected information was used to determine the collapsible soils localities in the study area. founding on the field study; there was no important variation in soil visual observation, therefore four pits were selected to perform laboratory experiments. 2.2.1. sampling techniques founded on the pits locations, disturbed soil samples from four sites were taken at 1.4 m depth. the soil is considered non-cohesive and difficult to obtain undisturbed soils samples. and also, the undisturbed samples have tendency to be affected through transportation due to the large distance from the study area to the laboratory site. therefore disturbed samples were taken for laboratory tests and soil samples preparation, considering the scarce investigation in the study area, and the analogous and continuous soil layers observed using visual description of the soil from the pits. asian review of environmental and earth sciences, 2022, 9(1): 9-17 12 © 2022 by the authors; licensee asian online journal publishing group 2.2.2. experimental study the tests performed are: determination of water content in natural state, particles size determination, atterberg limit, density, proctor test, specific gravity, consolidation tests. after different tests performed, the soils classification was carried out according to aashto and uscs systems. 2.2.2.1. preparation of soils specimens using a 1.4 m depth for each soil sample, the soil samples were kept in plastic bags and brought to the laboratory. the preparation of samples followed the aashto t87-86 standard. 2.3. laboratory tests the laboratory tests considered at first the preparation of the soils specimens submitted to experiments to determine the soils properties. the tests included the distribution of grains size, proctor test for the maximum dry density and the optimum water content, atterberg limits, specific gravity, and to end the oedometer test to determine the collapse potential of the soil. soil samples collected for various laboratory tests are important to determine the sectors where collapsible soils are met in the study area. the majority of the laboratory tests were performed founded on the aashto manual in the case of soil testing, and the use of astm manual for certain laboratory tests. 2.3.1. oedometer tests the tests were performed with a standard front loaded odometer, carefully following standard trials [6]. for the double odometer tests, dry soil samples were loaded in phases to σv = 200 kpa for the residual water content and inundated soil samples. for the single odometer tests, dry samples received a load in phases to σv = 100 kpa before being inundated just after loading to σv = 200 kpa. the swamping of samples just once loading in the 12 and 200 kpa is a deviation after usual practice [6], in which swamping is made next a full unsaturated soil samples by loading phase. though, the the results of the oedometer tests including the data repeatability recommend that values of collapse potential are comparable to those found by using normal practice. all soil samples were discharged in phases to σv = 12 kpa. for the stages with pressures of 12 and 200 kpa, there were successions of tests at wn = 6%, during the unloading phase. 2.4. collapse potential assessment the collapse potential recognition by international criteria is used from data provided by the genesis and collapsible soils properties being a large variety of dry densities for collapsible soils [16]. soil properties identification involves diverse mechanisms as a vital procedure. collapsible soils can be studied by using indirect and direct approaches. 2.4.1. direct methods these methods are based on values measurement by using single and doble oedometer tests in the laboratory considering the resultant stresses. then the results can predict the settlement potential including the evaluation of the collapse potential by using the astm d 5333 method in the laboratory. this method is based on the determination of the collapse potential ratio that will occur for a certain vertical pressure and an index for assessing the collapse potential. this method can be used for soil samples in different consevation states. 2.4.2. indirect methods in general, there are diverse approaches to study the susceptibility of soil to collapse, founded on the coefficient of subsidence (k) and kd values as shown in table 1 [26, 27]. table 1. criteria reported for the identification of soils susceptibility to collapse. authors year criterion denisov 1951 coefficient of saturation k = (saturated void index)/(natural void index) k = 0.5-0.75: highly collapsible soils k = 1.0: loamy clay soils not collapsible k = 1.5-2.00: non-collapsible soils priklonski 1952 k= (natural water ccontent liquid limit)/(plasticity index) kd ˂ 0: soils with high collapsibility kd ˃ 0: non-collapsible soils kd ˃ 0: swelling soils soviet bulding code 1962 l =(e0-el)/(1 + e) e0 e0: natural voids index l: saturated voids index when a saturation degree is 60%, if l> -0.1: collapsible soils feda 1964 kl= wo/sr-ip/ll wo: natural water content sr: natural degree of sturation ip: plasticity index ll: liquiquity limit when sr ˂100%, kl ˃ 0.85: collapsible soil table 2 shows a summary of several authors’ proposals to determine the potential collapse. asian review of environmental and earth sciences, 2022, 9(1): 9-17 13 © 2022 by the authors; licensee asian online journal publishing group table 2. potential collapse classification for constructions [6]. cp (%) severity of the problem from 0 to 1 none from 1 to 5 moderate from 5 to 10 problematic soils from 10 to 20 serious > 20 very serious while the oedometric tests are the most widely used in the laboratory to assess the possibility of collapse occurrence. although there are embodiments of oedometric tests, then for the present work the double odometric test was used under the conditions of natural water content and under saturated condition for the same sample. the methods for evaluating collapse potential in this research are summarized in the table 2. the validation of these methods presented in table 2 was carried out by comparison with the collapse potential, considering the following equations [6]: i=(∆ec)/[1+(enat/eonat)eomean] (1) ∆ec =[(enat/eonat) (esat/eosat)eomean] (2) eomean =[(eonat+ eosat)/2] (3) where; eonat and eosat are initial void ratios in the natural and saturated conditions, respectively. these parameters are obtained following the completion of the oedometric tests. the criteria for categorizing the collapse potential can be found in table 2. table 3. particles size. particles size (µm) type of soil percentage < 2 clay 6% 2 63 silt 18% ˃ 63 sand 77.9% table 4. soil density. specimens m0 ms m1 m2 γs (g/cm3) average 1 69 100 195 176 3 2 68 106 199 175 3 3 3 68 102 197 175 3 4 69 102 195 177 3 table 5. results of atterberg limits. parameters specimen 1 specimen 2 specimen 3 specimen 4 coefficient of uniformity (cu) 3.1 4.2 2.6 3.2 coefficient of curvature (cc) 1.5 1.7 1.6 1.8 liquidity limit, wl 17 16 19 18 plastic limit, wp 14 12 13 12 plasticity index, (p) 5.0 5.0 5.0 5.0 table 6. classification of settling soils according to collapse potential values [6]. collapse potential (cp), % problem gravity 0 1 non-collapsible soil 1 5 moderately collapsible soil 5 10 problematic soil 10 20 very collapsible soil > 20 very severe collapsible soil table 7. soil properties. ec 20 40 60 20 40 60 20 40 60 wo (%) 2 2 2 4 4 4 6 6 6 eo 0.881 0.853 0.822 0.756 0.715 0.675 0.681 0.641 0.611 𝛾d 14.18 14.46 14.59 15.18 15.90 16.10 15.86 16.24 1.655 cp (%) 14.88 12.30 12.40 15.56 13.72 12.79 16.88 14.07 13.98 figure 2. water content vs void ratio. asian review of environmental and earth sciences, 2022, 9(1): 9-17 14 © 2022 by the authors; licensee asian online journal publishing group table 8. values of collapse potential in the study area. sample locality authors denisov priklonski soviet building code feda parameter (k) parameter (kd) parameter (l) parameter (kl) 1 kintélé 0.65 -0.87 -0.08 0.98 2 lifoula 0.58 -0.67 -0.06 0.88 3 mandiélé 0.61 -0.31 -0.02 0.91 4 ignie 0.55 -0.29 -0.05 0.89 3. results cu = 3.3 and cc = 1.8 and the soil is well graduated. based on the methylene blue test, the soil is classified as a silty sand (0.2 1.5). particles densities are shown in table 4. then the soil is collapsible [6]. indeed, for the different pressures (σ) as well as the different energies of compaction (ec), the collapse potential (cp) differs from 12.40% to 14.88% (for an initial water content; w = 2%), from 12.79% to 15.56% for an initial water content w = 4%, and from 13.98 to 16.88% for an initial water content w = 6%). the void ratio reduction considered as one of the collapse index can be observed in figure 2. values obtained correspond to the category of very collapsible soil as shown in table 6. the collapse potential (cp) decreases when the energy of compaction (ec) increases. this can be noticed that the collapse is exalted by the action of water which easily eliminates the inter-granular bonds produced by capillary action and links formed by low clay content [28, 29]. these soils remained stable in wet conditions and become vulnerable to collapse after water infiltration. these types of soils have particular features with contribution to collapse such as metastable structure which results in great void ratio, young deposit, significant sensitivity, and weak inter-particles attachment. some compacted soil at optimum and small dry density can experience a metastable structure which is governed by shear strength, being bonds with a high dependence on capillary action. then the bonds can lose strength when an increase in water content can cause the collapse of soil structure at critical saturation degree. the collapse occurrence is often due to an increase in surcharge or water content and sometimes a combined action of these two parameters. in addition, the capillary effects between aggregates and granular particles decrease. this makes it easier to break the bonds among the particles and therefore collapse occurs. collapse behaviours are often seen in fine soils in which the fine particles are shown as connectors or sometimes as the blanket of granular particles [14]. it is noted the increase in the subsidence potential for an energy of compaction corresponding to 20 strokes for soils with a loose structure and many voids, causing the displacement of fine particles in different directions. conversely, in the case of compaction with 60 strokes once the soil becomes relatively dense the destruction of inter-granular bonds and the movement of fine particles are reduced, yet the subsidence potential still remains high. jennings and knight [6] gave a classification of soils according to the severity of the problem and the values of the subsidence potential from following equations: initial void index (e0) = (γs/γd) – 1 (4) cp (subsidence coefficient or collapse potential) = ∆h/h0 = ∆e/(1 + e0) (5) this classification is shown in the table 6. considering as an indication, we can consider that a soil is not very compressible when cc < 0.2, compressible when 0.2 < cc <0.7, very compressible when 0.7 < cc. others results related to soil mechanical properties can be seen in table 7. the susceptibility of soils to collapse is founded on the geotechnical properties of soils and the collapse potential obtained from laboratory tests, considering the soils under dry condition. the ll and pi played also a vital role for collapsible soils classification. from table 6, the results of collapse potential notice that all soil samples used showed high sensitivity to collapse. commonly the soils under study showed a certain similarities about collapsibility analysis. figure 3. soil curve before compaction. asian review of environmental and earth sciences, 2022, 9(1): 9-17 15 © 2022 by the authors; licensee asian online journal publishing group the figures 3, 4 and 5 show the soil conditions under oedometric tests. in figure 5, it is shown the curves for the dry and saturated conditions, respectively. these curves show that the collapse occurrence depends on the water content. then, it is noticed that once the water content increases in the soil, it becomes unstable causing a sudden collapse with the decrease in the shear strength [1]. due to the non-cohesive nature of the soil samples, the difficulty of collecting undisturbed samples was pronounced. therefore, the tests of single oedometer considered soil samples prepared according to astm d 5333 procedures. also, the loading conditions indicated in astm d 5333, supplementary oedometer tests were performed on remoulded samples swamped at the real loading conditions after final samples preparation. then the collapse potential for remoulded samples and considering the natural densities based on the severity of collapse is minor to reasonable as shown in figure 3. in addition, the collapse potential for soil samples with maximum dry densities is met within the very slight severity of collapse (figure 4 and table 6). figure 4. soil curve after compaction. figure 5. double oedometer test curve. asian review of environmental and earth sciences, 2022, 9(1): 9-17 16 © 2022 by the authors; licensee asian online journal publishing group figure 6. soils behaviour using the double oedometer test. from the figure 6 it is observed that the soil remains collapsible and its collapse potential can be considerably reduced by compaction. this compaction has tendency to reduce the soil void index and makes it denser to resist against collapse phenomena. in general, founded on the results obtained from the field and laboratory tests; one may assess the collapse potential in accordance with different criteria. the collapse potential evaluation by using the soils physical properties as an indirect method is based on the values of the collapse potential. 4. discussion different collapse criteria were suggested to determine the soil responsibility face to collapse. priklonski’s criterion, is based on the liquidity index for soil collapse expectations, where the soil is collapsible when the liquidity index is lesser than zero [26]. therefore, using the priklonski’s criterion the soil in the study area is collapsible by compaction. the results showed that all soil samples showed moderate to high collapse. generally some similarities found on the collapsible soils met in the study area refer to geological and environmental conditions. from tables 5, 6, 7 and 8, comparison can be made among the properties of collapsible soils for a good acknowledge about the collapse phenomenon in the study area. even though clevenger [30] criterion was not used in the current study, but comparing results obtained from this criterion with those obtained in this study, this method stated by using the natural dry density. then it is noticed that, when the natural density is inferior to 12.6 kn/m3, an important settlement can be produced whereas once it is larger than 14.1 kn/m3, slight settlement can be produced [31]. this criterion using clay percentage indicates that once the clay content is among 16.0 % and 24.0 % the soil is collapsible and it becomes highly collapsible when the clay percentage is inferior to 16.0 %. then, the soil met in the study area is highly collapsible with a clay content lesser than 16% table 3. the soils parameters provide the soils susceptibility to collapse potential. it is noted that keeping the water content constant, it is observed a decrease in the collapse intensity with the increase of relative density [32]. it is also defined the maximum value of the collapse potential (cp) at 200 kpa pressure. this result can be explained by the intensity of the collapse which increases up to a certain level of stresses after which the collapse decreases [33]. table 7 also shows that the collapse potential (cp) decreases almost linearly, when the water content or the energy of compaction increases for a 200 kpa pressure and this type of soil behavior is the same regardless of the applied pressure. results observed in tables 7 and 8 agree with those obtained by some researchers [34]. 5. conclusions in general, founded on the results obtained from the field and laboratory tests; one may assess the collapse potential in accordance with different criteria. the collapse potential can be evaluated by using the soils physical properties as an indirect method and using values of the collapse potential as a direct method. soil collapse is a very complex phenomenon that involves a large number of intrinsic and adjacent parameters. results obtained defined the soil behaviour in the face of collapse potential. the results of identification tests, consistency and compressibility confirmed the collapsible behaviour of the soils found in the study area. the collapse potential may be reduced by using compaction. the compaction and the consolidation tests contribute to a suitable description of the collapsible soil. this work determined the cause of collapse experienced by different types of constructions built in the study area and can be used as a policy statement for similar areas to reduce the collapse incidence on constructions. references [1] d. g. fredlund and h. rahardjo, soil mechanics for unsaturated soils, 1st ed. canada: john wiley&sons, 1993. [2] c. d. f. rogers, "hydroconcolidation and subsidence of loess: studies from china, russia, north america and europe: in memory of jan sajgalik," engineering geology, vol. 37, pp. 83-113, 1994. [3] s. l. houston, w. n. houston, and d. j. spadola, "prediction of field collapse of soils due to wetting," journal of geotechnical engineering, vol. 114, pp. 40-58, 1988.available at: https://doi.org/10.1061/(asce)0733-9410(1988)114:1(40). [4] j. ian and d. f. chris, chapter 32 collapsible soils. in ice manual of geotechnical engineering vol. 39: thomas telford ltd, 2012. asian review of environmental and earth sciences, 2022, 9(1): 9-17 17 © 2022 by the authors; licensee asian online journal publishing group [5] m. y. fattah and b. a. dawood, "time-dependent collapse potential of unsaturated collapsible gypseous soils," world journal of engineering, vol. 17, pp. 283-294, 2020.available at: https://doi.org/10.1108/wje-09-2019-0276. [6] j. e. jennings and k. knight, "the additional settlement of foundation due to collapse of sandy soils on wetting," in proc. 4th proceeding of 4th international conference on soil mechanics and foundation engineering (icsmfe), 1957, pp. 316-319. [7] z. lin and s. wang, "collapsibility and deformation characteristics of deep-seated loess in china," engineering geology, vol. 25, pp. 271-282, 1988.available at: https://doi.org/10.1016/0013-7952(88)90032-4. [8] j. feda, "collapse of loess upon wetting," engineering geology, vol. 25, pp. 263-269, 1988.available at: https://doi.org/10.1016/0013-7952(88)90031-2. [9] n. y. denisov, "about the nature of high sensitivity of quick clays," osnov. fudam. mekh. grunt, vol. 5, pp. 5-8, 1963. [10] k. abbeche, f. hammoud, and t. ayadat, influence of relative density and clay fraction on soils collapse. in experimental unsaturated soil mechanics. berlin, heidelberg: springer, 2007. [11] k. knight, "the origin and occurrence of collapsing soils," in proceeding of 3rd regional conference of africa on soil mechanics and foundation engineering, 1963, pp. 127-130. [12] s. p. clemence and o. a. finbar, "design considerations for collapsible soils," journal of geotechnical and geoenvironmental engineering, vol. 5606, pp. 305-317, 1981. [13] l. barden, a. mcgown, and k. collins, "the collapse mechanism in partly saturated soil," engineering geology, vol. 7, pp. 49-60, 1973.available at: https://doi.org/10.1016/0013-7952(73)90006-9. [14] j. h. dudley, "review of collapsing soils," journal of the soil mechanics and foundations division, vol. 96, pp. 925-947, 1970.available at: https://doi.org/10.1061/jsfeaq.0001426. [15] k. schwartz, "collapsible soils," civil engineering= siviele ingenieurswese, vol. 27, pp. 379-393, 1985. [16] e. derbyshire, t. dijkstra, and i. smalley, genesis and properties of collapsible soils. dordrecht: kluwer: nato asi series – series c: mathematical and physical sciences, 1994. [17] s. l. houston, w. n. houston, and a.-m. wagner, "laboratory filter paper suction measurements," geotechnical testing journal, vol. 17, pp. 185-194, 1994.available at: https://doi.org/10.1520/gtj10090j. [18] d. g. fredlund and j. gan, the collapse mechanism of a soil subjected to one-dimensional loading and wetting. in genesis and properties of collapsible soils. dordrecht: springer, 1995. [19] z. lin, variation in collapsibility and strength of loess with age", in e derbyshire et al (eds), genesis and properties of collapsible soils. dordrecht: springer, 1995. [20] c. l. mcknight, "the stratigraphy and engineering geological characteristics of collapsible residual soils on the southern mozambique coastal plane," in proc of the 12th reg conf for africa on soil mech and geotech eng, rotterdam: balkema, 1999. [21] a. kempena, r. g. lacaba, y. v. milán, and t. h. columbié, "hazards mapping of water eriosn in brazzaville city," mines and geology, vol. 33, pp. 17-35, 2017. [22] g. samba and d. nganga, "minimum and maximum temperature trends in congo-brazzaville: 1932-2010," atmospheric and climate sciences, vol. 4, pp. 404-430, 2014.available at: https://doi.org/10.4236/acs.2014.43040. [23] l. matini and m. j. marie, "groundwater quality of southeastern brazzaville, congo," e-journal of chemistry, vol. 7, pp. 861-869, 2010.available at: https://doi.org/10.1155/2010/376107. [24] d. d. j. nzila, k. victor, w.-n. noël, n. m. mercia, y. m. salisou, and n.-n. d. prudence, "soils typology and floristic diversity of the forest of the “cité scientifique” of brazzaville, congo," open journal of ecology, vol. 8, pp. 286-304, 2018.available at: https://doi.org/10.4236/oje.2018.84018. [25] e. kadima, d. delvaux, s. sebagenzi, l. tack, and s. kabeya, "structure and geological history of the congo basin: an integrated interpretation of gravity, magnetic and reflection seismic data," basin research, vol. 23, pp. 499-527, 2011.available at: https://doi.org/10.1111/j.1365-2117.2011.00500.x. [26] v. a. priklonski, gruntovedenia-vtoraid chast. moscow: gosgeolzdat, 1952. [27] n. y. denisov, the engineering properties of loess and loess loams. moscow: gosstroiizdat, 1951. [28] a.-m. h. hawraa, m. y. fattah, and f. a. salman, "treatment of collapsibility of gypseous soils by dynamic compaction," geotechnical and geological engineering, vol. 30, pp. 1369-1387, 2012.available at: https://doi.org/10.1007/s10706-012-9552-z. [29] m. ali, "identifying and analyzing problematic soils," geotechnical and geological engineering, vol. 29, pp. 343-350, 2011.available at: https://doi.org/10.1007/s10706-010-9380-y. [30] w. a. clevenger, "experiences with loess as a foundation material," transactions american society for civil engineers, vol. 3, pp. 5180, 1985. [31] m. sasani and s. sagiroglu, "progressive collapse resistance of hotel san diego," journal of structural engineering, vol. 134, pp. 478488, 2008.available at: https://doi.org/10.1061/(asce)0733-9445(2008)134:3(478). [32] r. martin and n. j. delatte, "another look at the l'ambiance plaza collapse," journal of performance of constructed facilities, vol. 14, pp. 160–165, 2000.available at: https://doi.org/10.1061/(asce)0887-3828(2000)14:4(160). [33] b. r. ellingwood and d. o. dusenberry, "building design for abnormal loads and progressive collapse," computer-aided civil and infrastructure engineering, vol. 20, pp. 194-205, 2005.available at: https://doi.org/10.1111/j.1467-8667.2005.00387.x. [34] a.-o. a. fahad and h. m. aldaihani, "determination of the collapse potential of sabkha soil and dune sand arid surface soil deposits in kuwait," technology journal, vol. 83, pp. 93-100, 2021.available at: https://doi.org/10.11113/jurnalteknologi.v83.14863. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 1 © 2023 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 10, no. 1, 1-13, 2023 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v10i1.4407 © 2023 by the authors; licensee asian online journal publishing group detection of potentially gas flaring related pollution on vegetation cover and its health using remotely sensed data in the niger delta, nigeria barnabas o. morakinyo1,2,3,4 samantha lavender2,3 victor abbott2 ( corresponding author) 1department of surveying & geoinformatics, faculty of environmental sciences, baze university, abuja, nigeria. 2school of marine science & engineering, faculty of science & technology, university of plymouth, plymouth, uk. 3pixalytics ltd, plymouth, uk. 4argans ltd, plymouth, uk. 1,2,3,4email: barnabas.ojo@bazeuniversity.edu.ng 2,3email: smnthlavender@gmail.com 2email: jamesvictor2021a@gmail.com abstract detection of potentially gas flaring-related pollution on vegetation cover using remotely sensed data at 11 flaring sites in rivers state, nigeria is the emphasis of this research. 21 landsat 7 enhanced thematic mapper plus (etm+), and 4 landsat 8 operational land imager and thermal infrared sensor (oli-tirs) data dated from 21/04/2000 to 05/02/2022 with < 3 % cloud cover were used. normalized differential vegetation index (ndvi) was retrieved from corrected landsat 7 bands (1-4), and landsat 8 bands (2-5). corrected thermal band was used for the computation of land surface temperature (lst). change in ndvi (𝛿ndvi450-60)m and lst (𝛿lst60-450m) were computed. ndvi values at 60 m from the stack show that as the year increases, ndvi values around the stack reduces to almost zero. linear regression analysis was considered for (𝛿ndvi450-60)mn against (𝛿ndvi450-60)me, (𝛿ndvi450-60)mn against (𝛿ndvi450-60)ms, and (𝛿ndvi450-60)mn against (𝛿ndvi450-60)mw. only (𝛿ndvi450-60)mn against (𝛿ndvi450-60)mw give statistically significant results at 99 % confidence level (p-value = 0.0016). (𝛿ndvi45060)mn,e,s,w against (𝛿lst60-450)mn,e,s,w were considered and results show positive correlation but statistically insignificant. based on the results of this research, it can be concluded that flaring-related pollution can be detected on vegetation cover using landsat 7 and landsat 8 data in the niger delta. keywords: detection, landsat 7, landsat 8, niger delta, pollution, remotely sensed data, vegetation cover. citation | morakinyo, b. o., lavender, s., & abbott, v. (2023). detection of potentially gas flaring related pollution on vegetation cover and its health using remotely sensed data in the niger delta, nigeria. asian review of environmental and earth sciences, 10(1), 1– 13. 10.20448/arees.v10i1.4407 history: received: 7 november 2022 revised: 21 december 2022 accepted: 2 january 2023 published: 13 january 2023 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ......................................................................................................................................................................................... 2 2. materials and methods ...................................................................................................................................................................... 2 3. results and discussion ...................................................................................................................................................................... 5 4. conclusion ......................................................................................................................................................................................... 12 references .............................................................................................................................................................................................. 12 mailto:barnabas.ojo@bazeuniversity.edu.ng mailto:smnthlavender@gmail.com mailto:jamesvictor2021a@gmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v10i1.4407 https://orcid.org/0000-0002-5066-8071 https://orcid.org/0000-0002-5181-9425 https://orcid.org/0000-0003-3972-3102 asian review of environmental and earth sciences, 2023, 10(1): 1-13 2 © 2023 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes scientific knowledge on detection of potentially gas flaring-related pollution on the vegetation cover and its health using earth observation (eo) satellite data. 1. introduction extraction and processing of crude oil and natural gas in the niger delta have unfavourable and harmful effects on the environment [1-4]. oil spillage and gas flaring alter the attributes of the receiving environment, leading to its pollution and degradation [1-4]. among others, gas flaring is responsible for the contamination of vegetation in the niger delta [5] with destructive impacts on vegetation and agricultural pursuits [6]. for example, almost no vegetation grows in the area directly surrounded by the flare as a result of the tremendous carbon emissions and heat releases to the environment; and the acidic nature of the soil potential of hydrogen (ph) [2]. researchers have worked on gas flaring with different aims and methods internationally, for example [7] used sentinel-3a sea and land surface temperature radiometer (slstr) data to study flared gas volume and emission of black carbon globally. the impact of hydrogen sulphide (h2s) content and excess air on pollutant discharges at the 2 flare sites in iran using computational methodology with matrix laboratory (matlab) codes was examined by zoeir, et al. [8]. they stated that the impact of sulphur iii oxide (so3) is several times more destructive than that of sulphur ii oxide (so2) in acidic rains; and that sulphur iii oxide (so3) pass through a slow balance with water vapour available in the atmosphere and forms sulphuric acid (h2so4). h2so4 is a highly corrosive compound within acidic rains. acidic rain affects soil ph which in turn causes destruction of vegetation and plants. others studies on global gas flares includes atmospheric pollution [9, 10] and estimation of temperatures of vegetation fires [11] etc. in nigeria, some studies have been carried out regarding discharge of gas flare activities; and its effects on the environment and people. in the niger delta, ndinwa, et al. [6] used questionnaire to study the impacts of flared gas on the environment and health of the people of kwale communities, ndokwa west local government area. chukwu, et al. [12] and uyigue and enujekwu [13] adopted conventional methods by taking measurements on site using instruments, and collection of samples to study gas flaring impacts at 2 communities of mkpanak and iko, ibeno and eastern obolo local government areas respectively, akwa ibom state. the influence of flared gas on vegetation and water resources for the entire niger delta region was reviewed by seiyaboh and izah [14]. lawanson, et al. [15]worked on the consequences of gas flaring on the cassava plantations in the niger delta. such effects recorded on vegetation and agricultural activities includes deforestation [16] stunted growth of crops [6, 12] reduction of soil quality parameters [17] etc. the authors concluded that the comparison between the flaring and the control sites used for their researches show that the soil nutrients of the flaring sites were the lower. in addition, chukwu, et al. [12] recorded the influence of flared gas on plants and vegetation as the loss of leaves at a distance less than 1 km, withering (1-2 km), stunted growth (3-4 km), and wrinkling leaves (5-6 km) respectively from the flare stack. however, none of the existing studies on flared gas and its consequences/impacts on vegetation in the niger delta has used satellite data. furthermore, many scholars investigated the relationship between the normalized differential vegetation index (ndvi) and land surface temperature (lst) using different satellite data [18-26]. for example, allam, et al. [18] worked on the effect of land surface changes related to urbanization using landsat 7 enhanced thematic mapper plus (etm+) and landsat 8 operational land imager and thermal infrared sensor (oli-tirs) data in sebkha, oran, algeria. they focused on the multi-temporal relationship between surface temperature, land use and ndvi in the areas affected by salinity which was characterized by a specific geographical space and a fragile natural environment. bindajam, et al. [20] employed advanced spaceborne thermal emission and reflection radiometer (aster) data for the retrieval of ndvi and lst in the cities of abha-khamis-mushayet, southwestern province, saudi arabia. also, shah, et al. [19] used landsat 8 oli-tir data to examine ndvi and lst over built-up and vegetative areas from 2013-2020 in mehar taluka, dadu, sindh province, pakistan. furthermore, guha, et al. [21] used premonsoon landsat 5 thematic mapper (tm), landsat 7, and landsat 8 data for monitoring inter-relationship of lst with ndvi in raipur city, india. climate, vegetation types, land use, urbanization, etc. are factors influencing the correlation between the ndvi and the lst [27, 28]. generally, the results from the above researches stated that ndvi and lst showed opposite trends. this paper addressed 2 research questions: (1) can satellite data be used for detection of gas flaring-related pollution on vegetation cover and its health in the niger delta? (2) what is the spatial and temporal variability in satellite detectable flare related pollution on vegetation cover and its health in the niger delta? due to the above stated 2 research questions, the aim of this study is the generation of a nigeria-focused technique for detection of gas flaring-related pollution on vegetation cover and its health using landsat 7 and landsat 8 data. objectives for these 2 research questions are (1) identification of significant gas flaring sites in the niger delta; (2) determination of ndvi and lst for the selected sites; (3) parameterization of flare-related change in ndvi as (𝛿ndvi450-60)m; (4) detection of gas flaring-related pollution on vegetation cover and its health using ndvi data; (5) evaluation of the relationship between the spatial gradient in ndvi and that of the lst around the flare sites in the niger delta. 2. materials and methods 2.1. study area the study was conducted in rivers state of the niger delta region, nigeria figure 1. the selected 11 gas flaring sites used for the study are eleme petroleum refinery companies i and ii, bonny liquefied natural gas (lng) plant, onne, rukpokwu, umurolu, obigbo, alua, umudioga and chokocho flow stations; and sara oil well figure 1c. all sites are located within latitude 4° 40′ and 5° 01′ n and longitude 6° 50′ and 7° 01′ e [1, 2] figure 1c. in order to have adequate ndvi and lst data for appropriate analysis, (12 × 12) km area was studied around the flare stacks with landsat 7 and landsat 8 data. asian review of environmental and earth sciences, 2023, 10(1): 1-13 3 © 2023 by the authors; licensee asian online journal publishing group 2.2. data used and data processing 2 acquired data used for this research are 21 landsat 7 etm+ scene dated from 2000 to 2013; and 4 landsat 8 oli-tirs scene dated from 2018 to 2022 with <3 % cloud cover from the months of january to april, and november to december. they were acquired from the united states geological survey (usgs) website (https://earthexplorer.usgs.gov/). the selected data fall within the dry season in nigeria. hence, they are less cloudy. landsat 7 etm+ images consist of 8 spectral bands with a spatial resolution of 30 m for bands 1-5, and 7. the resolution for band 8 (panchromatic) is 15 m. landsat 8 oli-tirs images consist of 11 spectral bands with bands 1-7, and 9 having a spatial resolution of 30 m; and band 8 (panchromatic) is 15 m. the spatial resolution for landsat 7 band 6 (thermal infrared), and landsat 8 bands 10 and 11 (thermal infrared) are 60 m and 100 m respectively but all are re-sampled to 30 m pixels [29]. matlab programming codes were used for data processing. figure 1. a) map of africa showing nigeria [30]; b) map of nigeria [30]; c) map of rivers state with the 11 flaring sites examined [30]. 2.3. landsat reflectance retrieval the computation of the spectral reflectance for landsat 7 etm+multispectral bands (1-4) and landsat 8 olitirs multispectral bands (2-5) was carried out using equation 1, figure 2 which assumes lambertian surface reflectance [31]. 𝜌p= (𝜋 ×lλ× d²) ÷ (esunλ× cos𝜃𝑠) (1) where: 𝜌p = spectral reflectance. l = surface leaving radiance/ unit solid angle. 𝝅l = upwelling radiance. d = earth-sun distance/astronomical units. esunλ= mean solar exoatmospheric irradiances. 𝜃𝑠= solar zenith incident angle/°. 2.4. landsat normalized differential vegetation index (ndvi)retrieval ndvi is the most regularly used vegetation index is huang, et al. [32]; guha, et al. [33]. ndvi is an indicator of vegetation that is generally used in the study of vegetation and surface temperature relationship [34]. ndvi values are from −1 to +1 [31]. when ndvi value is −, it suggests surfaces like cloud, ocean, ice, water etc. ndvi values near zero indicate bare soil, sparse vegetation range from (0-0.01) to (0.1-0.5), and dense, green and healthy vegetation is 0.6 above. the algorithm for ndvi is: ndvi = (nir − r) / (nir + r) [18, 21] (2) where: nir = near infra-red reflectance, band 4 for landsat 7, and band 5 for landsat 8. r = red reflectance, band 3 for landsat 7, and band 4 for landsat 8. https://earthexplorer.usgs.gov/ asian review of environmental and earth sciences, 2023, 10(1): 1-13 4 © 2023 by the authors; licensee asian online journal publishing group for this research, atmospheric effects on landsat data was corrected figure 2 i.e. the cloud-masked reflectance was used for the computation of ndvi with equation 2. hence, ndvis data from 2000 to 2022 was employed for detecting and assessing the potentially gas flaring-related pollution on vegetation cover and health. quantitative analysis of a change in vegetation cover and health was evaluated with the computed ndvis at a given time using 2 analyses namely plot of ndvi versus distance from the flare in the north (n), east (e), south (s) and west (w) directions; and derivation of change in ndvi as (𝜹ndvi450-60)min the n, e, s and w directions. 2.5. landsat land surface temperature (lst) retrieval retrieval of lst from landsat data was carried out through radiative transfer equation in 3 stages [21, 35]. the 1st stage is the conversion of digital numbers (dn) of thermal bands to top of atmosphere (toa) radiance using equation 3 for landsat 7 data; and equation 4 for landsat 8 images. 𝐿𝜆 = ((𝐿𝑀𝐴𝑋𝜆 − 𝐿𝑀𝐼𝑁𝜆)/(𝑄𝐶𝐴𝐿𝑀𝐴𝑋 − 𝑄𝐶𝐴𝐿𝑀𝐼𝑁)) ∗ (𝑄𝐶𝐴𝐿 − 𝑄𝐶𝐴𝐿𝑀𝐼𝑁) + 𝐿𝑀𝐼𝑁𝜆 (3) where: lλ= spectral radiance (wm⁻²sr⁻¹µm⁻¹). qcal = quantized calibrated pixel value in dn. lminλ= spectral radiance scaled to qcalmin (wm⁻²sr⁻¹µm⁻¹). lmaxλ= spectral radiance scaled to qcalmax (wm⁻²sr⁻¹µm⁻¹). qcalmin = minimum quantized calibrated pixel value in dn = 1. qcalmax = maximum quantized calibrated pixel value in dn = 255. 𝐿𝜆 = 𝑀𝐿 ∗ 𝑄𝐶𝐴𝐿 + 𝐴𝐿 (4) where ml= band multiplicative rescaling factor; al= band additive rescaling factor. ml and al are available in the metadata file of landsat 8 data. lλ and qcal in (4) are the same as those in (3). conversion of toa radiance of thermal band to surface-leaving radiance using atmospheric correction tool moderate-resolution atmospheric radiance and transmittance (modtran 4.1) for the removal of the effects of the atmosphere is the 2nd stage [36]. the surface-leaving radiance lt is calculated using equation 5 [37]: 𝐿𝑇 = (𝐿𝜆 − 𝐿𝜇 − 𝜏 (1 − 휀)𝐿𝑑 )/𝜏휀 (5) where lμ, ld and τ= upwelling radiance, downwelling radiance, and atmospheric transmission respectively. they are atmospheric correction parameters for landsat thermal band. ε = emissivity of land covers (lc) type. for this study, ε was calculated based on 4 lc (vegetation, built area, soil and water) types of each site. for the 3rd stage, the surface-leaving radiance is converted to lst using landsat estimate of the planck curve equation 6 [38] figure 2: lst = k2 ln((k1/lλ) + 1) (6) where, lst = land surface temperature in kelvin (k); k1 and k2 = thermal band calibration constants table 1. lsts for vegetation, built area, soil and water were retrieved but only lsts for vegetation was adopted for the analysis. table 1. calibration constants k1 and k2 for landsat 7 and landsat 8 data. calibration constants landsat 7 etm+ landsat 8 band 10 landsat 8 band 11 k1 (wm-2sr-1μm-1) 666.09 774.89 480.89 k2 (k) 1282.71 1321.08 1201.14 source: usgs [29]. figure 2. flow chart for the methodology adopted. 2.6. ndvi versus distance at 60 m and 450 m distance from the flare stack, values of ndvis were recorded figure 3 in the n, e, s and w directions. also, the range of ndvis values was computed. asian review of environmental and earth sciences, 2023, 10(1): 1-13 5 © 2023 by the authors; licensee asian online journal publishing group 2.7. change in ndvi (𝛿ndvi450-60)m and lst (𝛿lst60-450)m change in ndvi (𝛿ndvi) is the difference in the values of ndvi recorded at 450 m distance from the flare stack and that of the values of ndvis obtained at 60 m from the stack. i.e. ndvi450– ndvi60m= (𝛿ndvi450-60)m. figure 3 is the schematic diagram for (𝛿ndvi450-60)m. (𝛿ndvi450-60)m was computed for n, e, s and w directions, hence, (𝛿ndvi450-60)mn, (𝛿ndvi450-60)me, (𝛿ndvi450-60)ms and (𝛿ndvi450-60)mw were obtained. this is to help in assessing the vegetation cover and its health in the 4 directions. figure 3. schematic diagram for change in ndvi (𝜹ndvi450-60)m. for change in lst (𝜹lst60-450)m, it is the difference in the values of lsts at the 60 m from the flare stack and that of values of lst at 450 m from the flare stack [1, 5]. i.e. lst60− lst450m= (𝛿lst60-450)m. this means that the distance adopted for the computation of (𝛿ndvi45060)m is the reverse of the distance chosen for the computation of (𝛿lst60-450)m. 2.8. linear regression analysis ndvi-lst relationship has been investigated by researchers using linear regression analysis. such researchers include [18, 19, 39]. in addition, non-linear regression was employed by cleland, et al. [40]; sparks and tryjanowski [41]; dose and menzel [42] for studying the effects of global change on plant phenology. this study adopted linear regression analysis because non-linear regression gives no better results when tested. hence, (𝛿ndvi450-60)m and (𝛿lst60-450)m relationship in the n, e, s and w were examined when no data is zero in order to eliminate the effects of uncertainties. when (𝛿ndvi450-60)m= 0, it means that the values of ndvi at both 60 m and 450 m from the stack are equal, suggesting an uncertain condition. similarly, when (𝛿lst60-450)m= 0, it means that the values of lst at 60 m and 450 m from the stack are equal; suggesting the availability of other heat sources at 450 m or no burning on the stack at the time of satellite overpass. table 15 presents r-values and p-values results obtained from the analysis. n =total number of each (𝛿ndvi450-60)m’s and (𝛿lst60-450)m’s used, r-values show the type of correlation that existed between them, and p-values show whether the results obtained are statistically significant or insignificant with apriori 𝛼 = 0.01. 3. results and discussion 3.1. ndvi versus distance tables 2-13 present the values of ndvi recorded at 60 m and 450 m from the stack for the 11 sites studied for the year 2000, 2011 and 2022 respectively. table 2. ndvi retrieved at 60 m and 450 m from the stack (north direction) (2000). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.35 0.74 0.39 eleme refinery ii 0.18 0.52 0.34 onne 0.22 0.75 0.53 umurolu 0.22 0.48 0.26 bonny lng 0.20 0.50 0.30 alua 0.18 0.76 0.58 rukpokwu 0.20 0.68 0.48 obigbo 0.19 0.53 0.34 chokocho 0.18 0.56 0.38 umudioga 0.21 0.71 0.50 sara 0.18 0.62 0.44 asian review of environmental and earth sciences, 2023, 10(1): 1-13 6 © 2023 by the authors; licensee asian online journal publishing group table 3. ndvi retrieved at 60 m and 450 m from the stack (east direction) (2000). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.41 0.78 0.37 eleme refinery ii 0.48 0.63 0.15 onne 0.27 0.77 0.50 umurolu 0.36 0.54 0.18 bonny lng 0.41 0.58 0.17 alua 0.36 0.74 0.38 rukpokwu 0.49 0.75 0.26 obigbo 0.35 0.64 0.29 chokocho 0.32 0.59 0.27 umudioga 0.40 0.75 0.35 sara 0.34 0.70 0.36 table 4. ndvi retrieved at 60 m and 450 m from the stack (south direction) (2000). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.47 0.82 0.35 eleme refinery ii 0.30 0.60 0.30 onne 0.34 0.71 0.37 umurolu 0.35 0.56 0.21 bonny lng 0.32 0.58 0.26 alua 0.31 0.79 0.48 rukpokwu 0.36 0.74 0.38 obigbo 0.35 0.59 0.24 chokocho 0.25 0.64 0.39 umudioga 0.26 0.77 0.51 sara 0.21 0.68 0.47 table 5. ndvi retrieved at 60 m and 450 m from the stack (west direction) (2000). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.38 0.83 0.45 eleme refinery ii 0.21 0.62 0.41 onne 0.25 0.84 0.59 umurolu 0.27 0.60 0.33 bonny lng 0.38 0.58 0.20 alua 0.36 0.84 0.48 rukpokwu 0.37 0.74 0.37 obigbo 0.30 0.61 0.31 chokocho 0.25 0.69 0.44 umudioga 0.24 0.77 0.53 sara 0.44 0.73 0.29 table 6. ndvi retrieved at 60 m and 450 m from the stack (north direction) (2011). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.25 0.68 0.43 eleme refinery ii 0.10 0.59 0.49 onne 0.17 0.71 0.54 umurolu 0.18 0.50 0.32 bonny lng 0.16 0.48 0.32 alua 0.12 0.79 0.67 rukpokwu 0.13 0.62 0.49 obigbo 0.14 0.59 0.45 chokocho 0.11 0.54 0.43 umudioga 0.16 0.73 0.57 sara 0.12 0.55 0.43 table 7. ndvi retrieved at 60 m and 450 m from the stack (east direction) (2011). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.21 0.66 0.36 eleme refinery ii 0.18 0.57 0.39 onne 0.22 0.71 0.49 umurolu 0.23 0.52 0.29 bonny lng 0.21 0.45 0.24 alua 0.21 0.75 0.58 rukpokwu 0.20 0.60 0.40 obigbo 0.17 0.57 0.38 chokocho 0.19 0.51 0.33 umudioga 0.23 0.71 0.50 sara 0.15 0.53 0.36 asian review of environmental and earth sciences, 2023, 10(1): 1-13 7 © 2023 by the authors; licensee asian online journal publishing group table 8. ndvi retrieved at 60 m and 450 m from the stack (south direction) (2011). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.32 0.61 0.29 eleme refinery ii 0.20 0.50 0.30 onne 0.23 0.64 0.41 umurolu 0.23 0.45 0.22 bonny lng 0.16 0.43 0.27 alua 0.12 0.68 0.56 rukpokwu 0.13 0.55 0.42 obigbo 0.14 0.69 0.55 chokocho 0.11 0.55 0.44 umudioga 0.16 0.69 0.53 sara 0.12 0.58 0.46 table 9. ndvi retrieved at 60 m and 450 m from the stack (west direction) (2011). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.25 0.73 0.48 eleme refinery ii 0.14 0.61 0.47 onne 0.19 0.68 0.49 umurolu 0.20 0.51 0.31 bonny lng 0.18 0.50 0.32 alua 0.14 0.68 0.54 rukpokwu 0.16 0.58 0.42 obigbo 0.20 0.57 0.37 chokocho 0.15 0.53 0.38 umudioga 0.17 0.69 0.52 sara 0.16 0.52 0.36 table 10. ndvi retrieved at 60 m and 450 m from the stack (north direction) (2022). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.12 0.70 0.58 eleme refinery ii 0.12 0.60 0.48 onne 0.12 0.71 0.59 umurolu 0.13 0.52 0.39 bonny lng 0.14 0.55 0.41 alua 0.11 0.68 0.57 rukpokwu 0.13 0.71 0.58 obigbo 0.12 0.58 0.46 chokocho 0.13 0.57 0.44 umudioga 0.10 0.65 0.55 sara 0.11 0.58 0.47 table 11.ndvi retrieved at 60 m and 450 m from the stack (east direction) (2022). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.12 0.71 0.59 eleme refinery ii 0.11 0.59 0.48 onne 0.12 0.68 0.56 umurolu 0.11 0.53 0.42 bonny lng 0.10 0.57 0.47 alua 0.13 0.64 0.51 rukpokwu 0.12 0.70 0.58 obigbo 0.11 0.60 0.49 chokocho 0.10 0.53 0.43 umudioga 0.12 0.61 0.49 sara 0.10 0.51 0.41 table 12. ndvi retrieved at 60 m and 450 m from the stack (south direction) (2022). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.10 0.55 0.45 eleme refinery ii 0.13 0.64 0.51 onne 0.08 0.68 0.60 umurolu 0.11 0.58 0.47 bonny lng 0.13 0.61 0.48 alua 0.11 0.63 0.52 rukpokwu 0.12 0.61 0.49 obigbo 0.09 0.49 0.40 chokocho 0.08 0.50 0.42 umudioga 0.08 0.64 0.56 sara 0.10 0.60 0.50 asian review of environmental and earth sciences, 2023, 10(1): 1-13 8 © 2023 by the authors; licensee asian online journal publishing group table 13. ndvi retrieved at 60 m and 450 m from the stack (west direction) (2022). flaring site ndvi at 60 m ndvi at 450 m (𝜹ndvi450-60)m eleme refinery i 0.11 0.59 0.48 eleme refinery ii 0.14 0.62 0.48 onne 0.13 0.67 0.54 umurolu 0.09 0.60 0.51 bonny lng 0.10 0.54 0.44 alua 0.12 0.63 0.51 rukpokwu 0.11 0.65 0.54 obigbo 0.09 0.54 0.45 chokocho 0.10 0.57 0.47 umudioga 0.12 0.68 0.56 sara 0.11 0.61 0.50 generally, tables 2-13 show that the values of ndvi at 60 m from the flare stack is much lower. for example for the year 2022, ndvis recorded are the lowest (0.08-0.14). this suggests little or no vegetation cover, bear soil etc within the area. however, at 450 m from the stack, the values of ndvi are higher (0.43-0.84) which suggests that the vegetation cover is not sparse but green and healthy. therefore, the results showed that the vegetation cover and its health around the flare stack have been negatively affected by the flare leading to the sparse or no vegetation cover [21, 43]. ndvi values at 60 m from the flare reduce even to almost zero while lst values are higher. this is supported by previous researches [18, 20, 22-26]. this suggest that the vegetation cover is unhealthy and polluted, some have died, many are dying, while others have been reduced to almost bear soil as a result of the continuous effects of pollution from the flare. however, the ndvi values at 450 m did not follow a uniform trend, their values changes. this may be resulted from some external activities apart from gas flaring within the area. 3.2. change in ndvi (𝜹ndvi450-60)m figures 4-6 are the plots for the (𝛿ndvi450-60)mn against (𝛿ndvi450-60)me, (𝛿ndvi450-60)mn against (𝛿ndvi450-60)ms and (𝛿ndvi450-60)mn against (𝛿ndvi450-60)mw for the 11 facilities studied. the number (n) of (𝛿ndvi450-60)m used for each of the plot is 348. data for each facility is identified using the colour of the stack height. for exampleeleme refinery i has the stack height of 50 m and that of eleme refinery ii is 65 m. hence, all deep red and brown points in these figures are from these 2 refineries. figure 4. (𝜹ndvi450-60)mn against (𝜹ndvi450-60)me. stack height asian review of environmental and earth sciences, 2023, 10(1): 1-13 9 © 2023 by the authors; licensee asian online journal publishing group figure 5. (𝜹ndvi450-60)mn against (𝜹ndvi450-60)ms. figure 6. (𝜹ndvi450-60)mn against (𝜹ndvi450-60)mw. table 14 presents the results obtained when (𝛿ndvi450-60)mn versus (𝛿ndvi450-60)me, (𝛿ndvi450-60)mn versus (𝛿ndvi450-60)ms and (𝛿ndvi450-60)mn versus (𝛿ndvi450-60)mw relationships are considered. all results show positive correlation, but only (𝛿ndvi450-60)mn versus (𝛿ndvi450-60)mw give statistically significant result at 99 % confidence level (p-values = 0.0016) whilst the other 2 are not statistically significant. table 14. results for (𝜹ndvi450-60)m against north, east, south and west directions with 𝜶 = 0.01. relationship r-value p-value type of correlation (𝛿ndvi450-60)mn v (𝛿ndvi450-60)me 0.08 0.11 positive (+) (𝛿ndvi450-60)mn v (𝛿ndvi450-60)ms 0.10 0.07 positive (+) (𝛿ndvi450-60)mn v (𝛿ndvi450-60)mw 0.17 0.00 positive (+) stack height stack height asian review of environmental and earth sciences, 2023, 10(1): 1-13 10 © 2023 by the authors; licensee asian online journal publishing group 3.3. linear regression analysis for (𝜹ndvi450-60)m against (𝜹lst60-450)m table 15 presented the results of the analysis of (𝛿ndvi450-60)m against (𝛿lst60-450)m in the n, e, s, and w directions. the total number (n) of (𝛿ndvi450-60)m against (𝛿lst60-450)m for each facility used for the analysis in the 4 directions, the r-values and p-values obtained in the 4 directions are presented. table 15. (𝜹ndvi450-60)m against (𝜹lst60-450)m (when both > 0) with 𝜶 = 0.01. facility number (n), r-value, p-value (north direction) number (n), r-value, p-value (east direction) number (n), r-value, p-value (south direction) number (n), r-value, p-value (west direction) 1: eleme i 15.0 0.56 0.03 14.0 -0.22 0.44 15.0 -0.20 0.45 13.0 -0.06 0.81 2: eleme ii 17.0 0.16 0.53 19.0 -0.02 0.87 17.0 0.32 0.19 17.0 0.60 0.01 3: onne 23.0 -0.13 0.44 27.0 0.13 0.45 27.0 0.14 0.42 31.0 -0.31 0.07 4: umurolu 22.0 -0.06 0.79 29.0 -0.14 0.53 28.0 -0.24 0.23 27.0 0.03 0.90 5: bonny 15.0 0.17 0.62 24.0 0.14 0.65 20.0 -0.15 0.62 23.0 0.22 0.21 6: alua 20.0 0.23 0.32 17.0 -0.18 0.62 20.0 0.02 0.98 18.0 0.15 0.46 7: rukpokwu 30.0 -0.17 0.32 26.0 -0.27 0.17 31.0 0.42 0.03 30.0 -0.01 0.98 8: obigbo 24.0 -0.08 0.72 18.0 0.16 0.46 20.0 -0.20 0.36 18.0 -0.37 0.11 9: chokocho 21.0 -0.20 0.38 20.0 0.27 0.25 22.0 0.16 0.42 20.0 0.29 0.22 10: umudioga 12.0 -0.04 0.86 14.0 -0.14 0.33 16.0 0.42 0.06 18.0 -0.03 0.95 11: sara 15.0 -0.09 0.72 25.0 0.17 0.35 31.0 -0.04 0.83 29.0 -0.09 0.68 in table 15, eleme refineries i and ii, bonny lng and alua flow station have positive (+) correlation and statistically insignificant results in the n direction. onne, umurolu, rukpokwu, obigbo, chokocho, umudioga flow stations, and sara oil well show negative (−) r-values and insignificant p-values in the n direction. in the e direction, eleme refineries i and ii; umurolu, alua and umudioga flow stations also have − r-values and insignificant p-values; and bonny lng; onne, obigbo, chokocho flow stations; and sara oil well have a + correlation and insignificant results. in the s direction eleme refinery, i; bonny lng; and umurolu and obigbo flow stations; and sara oil well give − r-values and insignificant p-values. furthermore, eleme refinery ii; onne, alua, rukpokwu, chokocho and umudioga flow stations have + r-values and insignificant p-values. finally, in the w direction, eleme refinery i; onne, rukpokwu, obigbo, umudioga flow stations; and sara oil well show − r-values and insignificant p-values. eleme refinery ii; bonny lng; umurolu, alua and chokocho flow stations show + r-values and insignificant p-values. results in table 16 are obtained from the linear regression analysis for (𝛿ndvi450-60)m and (𝛿lst60-450)m when north, east, south, and west directions were evaluated with 𝛼 = 0.01 for all the 11 facilities processed together. table 16. results obtained for 𝜹ndvi against 𝜹lst with 𝜶 = 0.01. relationship number r-values p-values type of correlation (𝛿ndvi450-60)mn v (𝛿lst60-450)mn 214 0.00 0.97 positive (+) (𝛿ndvi450-60)me v (𝛿lst60-450)me 233 0.09 0.20 positive (+) (𝛿ndvi450-60)ms v (𝛿lst60-450)ms 249 0.03 0.20 positive (+) (𝛿ndvi450-60)mw v (𝛿lst60-450)mw 244 0.10 0.11 positive (+) figures 7-10 show the plots of the (𝛿ndvi450-60)mn versus (𝛿lst60-450)mn, (𝛿ndvi450-60)me versus (𝛿lst60450)me, (𝛿ndvi450-60)ms versus (𝛿lst60-450)ms, and (𝛿ndvi450-60)mw versus (𝛿lst60-450)mw. the scale bar is an arbitrary chosen number for the identification of individual facility. for example, 1 represents eleme refinery i, 5 for bonny lng plant and 11 is for sara flow station. asian review of environmental and earth sciences, 2023, 10(1): 1-13 11 © 2023 by the authors; licensee asian online journal publishing group figure 7. (𝜹ndvi450-60)mn against (𝜹lst60-450)mn. figure 8.(𝜹ndvi450-60)me against (𝜹lst60-450)me. figure 9. (𝜹ndvi450-60)ms against (𝜹lst60-450)ms. facility number numbernumber facility number facility number asian review of environmental and earth sciences, 2023, 10(1): 1-13 12 © 2023 by the authors; licensee asian online journal publishing group figure 10. (𝜹ndvi450-60)mw against (𝜹lst60-450)mw. 4. conclusion only the correlation coefficient for eleme i in the n direction (0.5558) and eleme ii in the w direction (0.6002) show that there is linear interdependence of the 2 variables, (𝛿ndvi450-60)m and (𝛿lst60-450)m (table 15). however, the rest 9 facilities show non-linear interdependence of the 2 variables in the n, e, s and w. therefore, due to lack of significant correlations no conclusions can be drawn about the effect of the prevailing wind direction (south) in the niger delta on any of the relationship between (𝛿ndvi450-60)m and (𝛿lst60-450)m. also, the results in table 16 for the 4 relationships (𝛿ndvi450-60)mn against (𝛿lst60-450)mn, (𝛿ndvi450-60)me against (𝛿lst60-450)me, (𝛿ndvi450-60)ms against (𝛿lst60-450)ms, and (𝛿ndvi450-60)mw against (𝛿lst60-450)mw considered shows positive correlation but statistically insignificant results. based on the results obtained for this research, it can be concluded that gas flaring related pollution can be detected on vegetation cover and its health using landsat 7 and landsat 8 remotely sensed data in the niger delta. some challenges are encountered in this research, for example, the available landsat data covers only dry season in nigeria, hence a further research is required to examine and compare the ndvi and lst results for the rainy period data too. the recommendations made regarding this research are: (1) nigerian government should make sure the exorbitant penalty fee is paid by defaulters’ oil and gas companies who refuse to adhere to flaring law and regulations; (2) all nigerian should not lose the focus for the quest of having zero gas flaring in nigeria. references [1] b. morakinyo, s. lavender, and v. abbott, "investigation of potential prevailing wind impact on land surface temperature at gas flaring sites in the niger delta, nigeria," international journal of environment and geoinformatics, vol. 9, no. 1, pp. 179-190, 2022. https://doi.org/10.30897/ijegeo.968687 [2] b. morakinyo, s. lavender, and v. abbott, "the methodology and results from ground validation of satellite observations at gas flaring sites in nigeria," international journal of environment and geoinformatics, vol. 8, no. 3, pp. 290-300, 2021. https://doi.org/10.30897/ijegeo.749664 [3] b. morakinyo, s. lavender, and v. abbott, "retrieval of land surface temperature from earth observation satellites for gas flaring sites in the niger delta, nigeria," international journal of environmental monitoring and analysis, vol. 8, no. 3, pp. 59-74, 2020. https://doi.org/10.11648/j.ijema.20200803.13 [4] b. morakinyo, s. lavender, j. schwarz, and v. abbott, "mapping of land cover and estimation of their emissivity values for gas flaring sites in the niger delta," british journal of environmental sciences, vol. 7, no. 2, pp. 31-58, 2019. [5] b. o. morakinyo, "flaring and pollution detection in the niger delta using remote sensing," ph.d thesis, university of plymouth, plymouth, united kingdom, 2015. [6] g. c. c. ndinwa, s. a. akpafun, and c. o. chukumah, "perceived environmental and health impacts of gas flaring on residents in kwale communities, southern nigeria," asian journal of energy transformation and conservation, vol. 4, no. 1, pp. 1-21, 2020. [7] a. caseiro, b. gehrke, g. rücker, d. leimbach, and j. w. kaiser, "gas flaring activity and black carbon emissions in 2017 derived from the sentinel-3a sea and land surface temperature radiometer," earth system science data, vol. 12, no. 3, pp. 2137-2155, 2020. https://doi.org/10.5194/essd-12-2137-2020 [8] a. zoeir, a. tabatabaei nejad, and e. khodapanah, "impact of h2s content and excess air on pollutant emission in sour gas flares," iranian journal of oil and gas science and technology, vol. 8, no. 1, pp. 1-10, 2019. [9] w. lu et al., "global proliferation of offshore gas flaring areas," journal of maps, vol. 16, no. 2, pp. 396-404, 2020. https://doi.org/10.1080/17445647.2020.1762773 [10] m. faruolo, t. lacava, n. pergola, and v. tramutoli, "on the potential of the rst-flare algorithm for gas flaring characterization from space," sensors, vol. 18, no. 8, p. 2466, 2018. https://doi.org/10.3390/s18082466 [11] a. caseiro et al., "persistent hot spot detection and characterisation using slstr," remote sensing, vol. 10, no. 7, p. 1118, 2018. https://doi.org/10.3390/rs10071118 [12] e. o. chukwu, m. o. faluyi, and i. j. adaji, "impact of gas flaring on climate change: a case study ofn niger delta region of nigeria," global scientific journals, vol. 9, pp. 1781-1790, 2021. [13] l. uyigue and f. enujekwu, "physicochemical analysis of gas flaring impact on the environment of host communities in the nigerdelta," journal of environment pollution and human health, vol. 5, no. 1, pp. 22-29, 2017. facility number https://doi.org/10.30897/ijegeo.968687 https://doi.org/10.30897/ijegeo.749664 https://doi.org/10.11648/j.ijema.20200803.13 https://doi.org/10.5194/essd-12-2137-2020 https://doi.org/10.1080/17445647.2020.1762773 https://doi.org/10.3390/s18082466 https://doi.org/10.3390/rs10071118 asian review of environmental and earth sciences, 2023, 10(1): 1-13 13 © 2023 by the authors; licensee asian online journal publishing group [14] e. i. seiyaboh and s. c. izah, "a review of impacts of gas flaring on vegetation and water resources in the niger delta region of nigeria," international journal of economy, energy and environment, vol. 2, no. 4, pp. 48-55, 2017. https://doi.org/10.11648/j.ijeee.20170204.11 [15] a. o. lawanson, a. m. a. imevbore, and v. o. fanimokun, "effects of waste-gas flares on the surrounding cassava plantations in the niger delta regions of nigeria," in proceedings, sixth symposium of the international society for tropical root crops/hosted by cip in lima, peru, 21-26 february 1983. lima, peru: international potato center (cip), 1984, 1984. [16] e. awulu, "gas flaring in nigeria: a crisis for the environment," academia letters, pp. 1-6, 2021. https://doi.org/10.20935/al3799 [17] p. okeke and c. okpala, "effects of gas flaring on selected arable soil quality indicators in the niger delta, nigeria," sky journal of soil science and environmental management, vol. 3, no. 1, pp. 001-005, 2014. [18] a. allam, a. hamou, d. mansour, m. rahila, and a. dif, "multi-temporal relationship between surface temperature, land use and normalized vegetation index," algerian journal of environmental science and technology, vol. 7, no. 3, pp. 2045-2050, 2021. [19] s. a. shah, m. kiran, a. nazir, and r. dars, "evaluation of land surface temperature and normalized difference vegetation index relationship using landsat 8 satellite images in mehar taluka, dadu," pakistan journal of geology, vol. 5, pp. 2521-2915, 2021. [20] a. a. bindajam, j. mallick, s. alqadhi, c. k. singh, and h. t. hang, "impacts of vegetation and topography on land surface temperature variability over the semi-arid mountain cities of saudi arabia," atmosphere, vol. 11, no. 7, p. 762, 2020. https://doi.org/10.3390/atmos11070762 [21] s. guha, h. govil, and p. diwan, "monitoring lst-ndvi relationship using premonsoon landsat datasets," advances in meteorology, vol. 2020, pp. 1-15, 2020. https://doi.org/10.1155/2020/4539684 [22] m. fatemi and m. narangifard, "monitoring lulc changes and its impact on the lst and ndvi in district 1 of shiraz city," arabian journal of geosciences, vol. 12, no. 4, pp. 1-12, 2019. https://doi.org/10.1007/s12517-019-4259-6 [23] f. ferrelli, m. a. h. cisneros, a. l. delgado, and m. c. píccolo, "spatial and temporal analysis of the lst-ndvi relationship for the study of land cover changes and their contribution to urban planning in monte hermoso, argentina," geographical analysis documents, vol. 64, no. 1, pp. 25-47, 2018. https://doi.org/10.5565/rev/dag.355 [24] s. naeem, c. cao, m. m. waqar, c. wei, and b. k. acharya, "vegetation role in controlling the ecoenvironmental conditions for sustainable urban environments: a comparison of beijing and islamabad," journal of applied remote sensing, vol. 12, no. 1, p. 016013, 2018. https://doi.org/10.1117/1.jrs.12.016013 [25] r. c. estoque, y. murayama, and s. w. myint, "effects of landscape composition and pattern on land surface temperature: an urban heat island study in the megacities of southeast asia," science of the total environment, vol. 577, pp. 349-359, 2017. https://doi.org/10.1016/j.scitotenv.2016.10.195 [26] z. n. li, d. sibo, and t. bohui, "review of methods for land surface temperature derived from thermal infrared remotely sensed data," journal of remote sensing, vol. 20, pp. 899-920, 2016. [27] s. guha, h. govil, a. k. taloor, n. gill, and a. dey, "land surface temperature and spectral indices: a seasonal study of raipur city," geodesy and geodynamics, vol. 13, no. 1, pp. 72-82, 2022. https://doi.org/10.1016/j.geog.2021.05.002 [28] y. ghobadi, b. pradhan, h. z. m. shafri, and k. kabiri, "assessment of spatial relationship between land surface temperature and landuse/cover retrieval from multi-temporal remote sensing data in south karkheh sub-basin, iran," arabian journal of geosciences, vol. 8, no. 1, pp. 525-537, 2015. https://doi.org/10.1007/s12517-013-1244-3 [29] usgs, "landsat 7 and landsat 8 specifications. national aeronautics and space administration [nasa], usa," retrieved: https://www.usgs.gov/faqs/what-are-band-designations-landsat-satellites. [accessed 01 july, 2021], 2013. [30] google earth, "map of africa showing nigeria, map of nigeria and map of rivers state with the 11 flaring sites examined. google, usa," retrieved: https://earth.google.com. [accessed 3 march, 2022], 2022. [31] z. song et al., "global land surface temperature influenced by vegetation cover and pm2. 5 from 2001 to 2016," remote sensing, vol. 10, no. 12, pp. 2034-2044, 2018. https://doi.org/10.3390/rs10122034 [32] s. huang, l. tang, j. p. hupy, y. wang, and g. shao, "a commentary review on the use of normalized difference vegetation index (ndvi) in the era of popular remote sensing," journal of forestry research, vol. 32, no. 1, pp. 1-6, 2021. https://doi.org/10.1007/s11676-020-01155-1 [33] s. guha, h. govil, a. dey, and n. gill, "analytical study of land surface temperature with ndvi and ndbi using landsat 8 oli and tirs data in florence and naples city, italy," european journal of remote sensing, vol. 51, no. 1, pp. 667-678, 2018. https://doi.org/10.1080/22797254.2018.1474494 [34] w. li, q. cao, k. lang, and j. wu, "linking potential heat source and sink to urban heat island: heterogeneous effects of landscape pattern on land surface temperature," science of the total environment, vol. 586, pp. 457-465, 2017. https://doi.org/10.1016/j.scitotenv.2017.01.191 [35] y. zhang, i. o. odeh, and c. han, "bi-temporal characterization of land surface temperature in relation to impervious surface area, ndvi and ndbi, using a sub-pixel image analysis," international journal of applied earth observation and geoinformation, vol. 11, no. 4, pp. 256-264, 2009. https://doi.org/10.1016/j.jag.2009.03.001 [36] a. berk, g. p. anderson, and p. k. acharya, modtran4 user’s manual, air force research laboratory. north andover, ma, usa: ontario corporation, 1999. [37] j. a. barsi, j. r. schott, f. d. palluconi, and s. j. hook, "validation of a web-based atmospheric correction tool for single thermal band instruments," in proceedings of spie, bellingham, wa, 7, 2005, vol. 5882. [38] g. chander and b. markham, "revised landsat-5 tm radiometric calibration procedures and postcalibration dynamic ranges," ieee transactions on geoscience and remote sensing, vol. 41, no. 11, pp. 2674-2677, 2003. https://doi.org/10.1109/tgrs.2003.818464 [39] c. zeng et al., "soil erosion evolution and spatial correlation 1 analysis in a typical karst geomorphology, using rusle with gis," solid earth discuss, vol. 8, pp. 721–736, 2017. https://doi.org/10.5194/se-8-721-2017 [40] e. e. cleland, i. chuine, a. menzel, h. a. mooney, and m. d. schwartz, "shifting plant phenology in response to global change," trends in ecology & evolution, vol. 22, no. 7, pp. 357-365, 2007. https://doi.org/10.1016/j.tree.2007.04.003 [41] t. sparks and p. tryjanowski, "the detection of climate impacts: some methodological considerations," international journal of climatology: a journal of the royal meteorological society, vol. 25, no. 2, pp. 271-277, 2005. https://doi.org/10.1002/joc.1136 [42] v. dose and a. menzel, "bayesian analysis of climate change impacts in phenology," global change biology, vol. 10, no. 2, pp. 259272, 2004. https://doi.org/10.1111/j.1529-8817.2003.00731.x [43] y. deng et al., "relationship among land surface temperature and lucc, ndvi in typical karst area," scientific reports, vol. 8, no. 1, pp. 1-12, 2018. https://doi.org/10.1038/s41598-017-19088-x asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://doi.org/10.11648/j.ijeee.20170204.11 https://doi.org/10.20935/al3799 https://doi.org/10.3390/atmos11070762 https://doi.org/10.1155/2020/4539684 https://doi.org/10.1007/s12517-019-4259-6 https://doi.org/10.5565/rev/dag.355 https://doi.org/10.1117/1.jrs.12.016013 https://doi.org/10.1016/j.scitotenv.2016.10.195 https://doi.org/10.1016/j.geog.2021.05.002 https://doi.org/10.1007/s12517-013-1244-3 https://www.usgs.gov/faqs/what-are-band-designations-landsat-satellites https://earth.google.com/ https://doi.org/10.3390/rs10122034 https://doi.org/10.1007/s11676-020-01155-1 https://doi.org/10.1080/22797254.2018.1474494 https://doi.org/10.1016/j.scitotenv.2017.01.191 https://doi.org/10.1016/j.jag.2009.03.001 https://doi.org/10.1109/tgrs.2003.818464 https://doi.org/10.5194/se-8-721-2017 https://doi.org/10.1016/j.tree.2007.04.003 https://doi.org/10.1002/joc.1136 https://doi.org/10.1111/j.1529-8817.2003.00731.x https://doi.org/10.1038/s41598-017-19088-x 14 © 2025 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 12, no. 1, 14-27, 2025 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v12i1.6936 © 2025 by the authors; licensee asian online journal publishing group flood forecasting using hec-hms model for sukkur district, pakistan fatima salman awan1 dhananjay singh2 nidhi nagabhatla3 ( corresponding author) 1,3united nations university institute on comparative regional integration studies, belgium. 1email: s78fawan@uni-bonn.de 3email: nnagabhatla@cris.unu.edu 2village satheri post office khatauli district muzaffarnagar, uttar pradesh, india. 2email: dsinghnmcg@gmail.com abstract this study investigates the applicability of the hydrologic engineering center’s hydrologic modeling system (hec-hms) for reliable flood forecasting in the sukkur district, pakistan, a lower indus basin region that suffers on average three major flood events per decade and experienced catastrophic inundation of over 1,200 km² of cropland during the 2022 monsoon. we delineated the 5,165 km² sukkur watershed into eight sub-basins using a 30 m srtmderived dem and applied hec-hms with locally calibrated parameters—initial and constant loss, scs unit hydrograph, and constant monthly baseflow—driven by daily rainfall (2018– 2022) from guddu, sukkur and kotri stations and six-hourly discharge at the sukkur gauge. representing the first calibrated hec-hms application with an eight-subbasin configuration in the region, this approach provides improved spatial resolution over lumped models. calibration on three flood peaks (july 2020, august 2021, august 2022) and validation against an independent september 2022 event yielded a nash-sutcliffe efficiency of 0.92 and a root mean square error of 55 m³/s, while the model provided an 18-hour lead time for peak discharge forecasts. these results demonstrate hec-hms’s strong potential as an operational earlywarning tool to enhance emergency preparedness and minimize flood impacts in sukkur and underscore the value of integrating real-time telemetry networks, coupling with twodimensional hydraulic models, and conducting comprehensive sensitivity analyses to further improve forecast accuracy and support decision-making. keywords: flood forecasting, flood risk assessment, hec-hms, hydrological modeling, early warnings systems, rainfall-runoff modeling citation | awan, f. s., singh, d., & nagabhatla, n. (2025). flood forecasting using hec-hms model for sukkur district, pakistan. asian review of environmental and earth sciences, 12(1), 14– 27. 10.20448/arees.v12i1.6936 history: received: 16 april 2025 revised: 23 june 2025 accepted: 10 july 2025 published: 25 july 2025 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. institutional review board statement: not applicable transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. this study followed all ethical practices during writing. competing interests: the authors declare that they have no competing interests. authors’ contributions: all authors contributed equally to the conception and design of the study. all authors have read and agreed to the published version of the manuscript. contents 1. introduction ...................................................................................................................................................................................... 15 2. methodology ..................................................................................................................................................................................... 18 3. results and discussions .................................................................................................................................................................. 24 4. conclusions ....................................................................................................................................................................................... 26 references .............................................................................................................................................................................................. 26 https://www.doi.org/10.20448/arees.v12i1.6917 https://orcid.org/0009-0004-6377-7033 https://orcid.org/0000-0002-5941-2048 https://orcid.org/0009-0002-1906-9473 mailto:s78fawan@uni-bonn.de mailto:nnagabhatla@cris.unu.edu mailto:dsinghnmcg@gmail.com https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ asian review of environmental and earth sciences, 2025, 12(1): 14-27 15 © 2025 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study is the first to calibrate hec-hms across four years of sukkur hydrometeorological data using an eight-subbasin configuration, achieving an 18-hour forecast lead time (nse = 0.92). it also outlines real-time telemetry integration and 2d hydraulic coupling to advance operational early-warning systems. 1. introduction 1.1. context and background the sukkur district in pakistan frequently experiences severe floods, significantly impacting lives, agriculture, and infrastructure, vividly highlighted by the catastrophic 2022 floods. the rate, regularity, magnitude, and likelihood of disasters have been increasing in the past few decades [1]. floods are catastrophic both in terms of loss of human life and finances. pakistan has a history of frequent and repeated flooding [2]. ninety percent of pakistan's population is affected by hazards and disasters, and it suffers from floods alone [3]. geographically, pakistan can be divided into three major sections mountains in the north, plateau in the southwest (balochistan) and the indus river plain in the middle [4]. flooding remains one of the most destructive natural hazards affecting pakistan, with significant impacts on infrastructure, agriculture, and communities, especially in regions along the indus river ali [5]. given these challenges, accurate and timely flood forecasting has become essential to disaster risk reduction efforts, enabling authorities to plan effective responses and mitigate potential damages [6]. despite many studies utilizing various hydrological models for flood prediction, there remains a critical gap regarding locally calibrated flood models specifically for sukkur. this gap limits the accuracy and applicability of predictions for effective disaster management in the region. therefore, this study aims to evaluate the effectiveness and accuracy of the hydrologic engineering center-hydrologic modeling system (hec-hms) in forecasting floods in sukkur using locally calibrated parameters. the findings of this study will provide local authorities with improved tools for flood forecasting and early warnings, significantly enhancing disaster preparedness and reducing flood impacts in the region. this paper is structured as follows: section 2 describes the study area and data, section 3 details methodology, section 4 presents results, section 5 discusses key findings, and section 6 concludes with practical implications and recommendations. figure 1. pakistan, location, and landforms detail. the map was prepared with the help of a digital elevation model (dem) and input into arcgis. dem is based on a 3-arc second resolution obtained from srtm. source: kamuju [7]. figure 1 illustrates the location of the study area within pakistan and the detailed landform characteristics derived from a 3-arc-second srtm digital elevation model processed in arcgis. asian review of environmental and earth sciences, 2025, 12(1): 14-27 16 © 2025 by the authors; licensee asian online journal publishing group 1.2. study area and introduction to hec hms the southern province of sindh is the most impacted by floods, as the indus river flows along a ridge, with the surrounding areas generally lying lower than the riverbed [8]. the sukkur region in sindh is particularly susceptible to flooding, exacerbated by heavy monsoon rains and overflow from the indus river. historically, seasonal floods in this area have resulted in displacement, loss of life, and economic setbacks [9]. during flooding, water that overflows from the river does not return to the main channel but instead inundates vast areas for extended periods, even after the flood peaks have subsided [10]. as the indus river enters sindh province, it flows within a 15 to 20 km-wide floodplain constrained by levees, often referred to as "bunds." surrounding this is a historical floodplain exceeding 200 km in width, where the river has historically shifted its course and meandered [10]. the sukkur barrage diverts a significant portion of the river's flow into feeder canals, while the guddu barrage upstream (with a designed discharge capacity of approximately 1.2 million cusecs) and the kotri barrage downstream (with a discharge capacity of around 875,000 cusecs) also play key roles in regulating floodwaters and managing seasonal discharge into downstream areas [10]. the sukkur district is in the sindh province of pakistan and lies along the indus river. the region is characterized by an arid to semi-arid climate, marked by hot summers and relatively milder winters [11]. annual rainfall is generally low, averaging between 100–200 mm; however, the area experiences significant seasonal variability due to monsoon influences, with up to 70–80% of the annual precipitation occurring during the monsoon season between july and september [12]. the study area encompasses the sukkur district and the surrounding flood-prone zones of the indus river basin. the modeled zone, which includes both the river's floodplain and the surrounding infrastructure, spans an approximate surface area of 5,165 square kilometers, based on administrative boundaries and hydrological catchment delineation. land use patterns in sukkur largely revolve around agriculture, particularly in areas benefiting from irrigation derived from the indus river, while urbanized zones dot the district’s landscape [13]. this combination of climate, land use, and the presence of a major river underscores the importance of accurately understanding the hydrological processes that govern runoff and river discharge in this region of interest, especially for flood management and water resource planning [14]. the indus river in sindh is regulated by three major barrages: guddu (upstream), sukkur (central study area), and kotri (downstream). these structures control flow diversion into irrigation canals and influence flood propagation in the region. figure 2. study area of sukkur district. asian review of environmental and earth sciences, 2025, 12(1): 14-27 17 © 2025 by the authors; licensee asian online journal publishing group figure 2 illustrates study area of sukkur district. figure 3. gauge stations. figure 3 shows gauge stations related to the study area. pakistan experiences precipitation from three main weather systems: monsoon depressions from the bay of bengal (the most significant), westerly waves from the mediterranean (winter rains), and seasonal lows from the arabian sea (cyclones) [15]. the country has four distinct seasons: hot and dry months (april–june), hot and moist monsoon months (july–september), a cool and dry period (october–november), and the coldest months (december–february) [16]. hydrologically, pakistan is divided into the indus basin, kharan basin, and makran coastal drainage area, each with unique flooding patterns requiring detailed understanding [17]. flood forecasting has been a critical area of research in hydrology, particularly for regions prone to recurring flood events. recent advancements in this field include integrating real-time data collection, machine learning techniques for predictive analytics, and using geographic information systems (gis) for detailed flood mapping [18]. globally, there has been a growing emphasis on community-based early warning systems and the development of models that account for the impacts of climate change, making flood forecasting more accurate and actionable for disaster management [19]. existing studies have extensively used hydrological models like hec-hms for simulating rainfall-runoff processes and predicting peak flows in various basins worldwide. for instance, studies conducted in catchments such as the gilgel abay in ethiopia [20] and al-adhaim in iraq [21] have demonstrated the effectiveness of these models in diverse geographical contexts. however, despite their applicability, most of these studies focus on general catchment areas without addressing localized flood behavior in specific regions with unique hydrological characteristics [19]. in the context of pakistan, several studies have examined flood risks along the indus river and its tributaries [22]. research by tariq and van de giesen [17] highlights flood management challenges in the indus basin, particularly in downstream areas like sindh province. the unique topography of the sukkur district — with the indus river flowing on elevated ground and vast surrounding floodplains — presents distinct flood dynamics that require detailed modeling and calibration [23]. 1.3. research gaps while flood forecasting models have been applied in pakistan, there is a gap in using hec-hms with precise calibration for local conditions in sindh, particularly for specific flood events. calibration is crucial as it ensures that the model parameters align with the unique hydrological characteristics of the region, thereby improving the accuracy of runoff predictions. accurate calibration considers localized variations in precipitation, soil type, and land use patterns—factors often overlooked by broader hydrological models. this, in turn, enhances disaster preparedness by providing more reliable forecasts, allowing authorities to implement timely interventions and reduce the socio-economic impact of floods [24]. asian review of environmental and earth sciences, 2025, 12(1): 14-27 18 © 2025 by the authors; licensee asian online journal publishing group this study addresses these gaps by implementing hec-hms with the specified hyetograph method to simulate rainfall-runoff processes based on time-series rainfall data from the pakistan meteorological department (pmd). the model focuses on localized calibration and validation using historical flood data, ensuring that it accurately reflects the hydrological behavior of the sukkur district. by simulating historical flood events, this research provides insights into rainfall-runoff behavior, which can predict about flood forecasting/ inundated areas, disaster risk reduction, and resilience planning in one of pakistan’s most flood-prone regions [25]. 1.4. methodology-concepts and approach the hydrologic engineering center’s hydrologic modeling system (hec-hms) is a widely used hydrological modeling tool developed by the u.s. army corps of engineers. this model has been effectively applied in diverse geographic contexts to simulate hydrological processes, assess runoff potential, and provide valuable predictions for flood management. hec-hms operates by integrating inputs from topographic, meteorological, and land use data to simulate rainfall-runoff processes, making it an asset in flood-prone areas such as sukkur [21, 26]. in studies of catchment areas, such as the hazara region in pakistan and al-adhaim in iraq, hec-hms has shown promise in simulating discharge patterns and identifying flood-prone zones [21]. for example, in the hazara catchment, researchers effectively used hec-hms with digital elevation models (dems) and geographic information system (gis) tools to map drainage pathways, calibrate curve numbers for runoff, and predict peak flows. these findings underscore the model's adaptability across different terrains and climates, suggesting that hec-hms is well-suited for flood forecasting in the sukkur region, which has comparable hydrological complexities [24]. flood prediction accuracy depends significantly on high-quality input data, such as precipitation records, land cover types, and soil characteristics. in hec-hms, key parameters include the soil conservation service curve number (scs-cn), which reflects land use and soil permeability, and muskingum routing, which helps simulate the movement of water within channels. studies have shown that the model can yield reliable predictions by adjusting these parameters based on regional data. for instance, research on the al-adhaim catchment in iraq achieved a high coefficient of determination (r²) between observed and simulated hydrographs, suggesting that calibrated parameters can produce realistic flow predictions even under varied climatic conditions [26]. the applicability of hec-hms in flood-prone areas is further supported by international studies that employed the model in combination with gis tools. in the gilgel abay catchment in ethiopia, the hec-hms model was used to simulate rainfall-runoff patterns with a focus on watershed response times, peak flow, and runoff distribution. similar methodologies can be applied to the sukkur region by utilizing land use maps, soil data, and historical rainfall records to simulate potential flood scenarios. the findings of these studies highlight the importance of precise calibration, which is often achieved through historical rainfall and discharge data, enabling the model to capture local hydrological dynamics and produce accurate flood forecasts [20]. 1.5. research scope and questions given the recurring flood risks in the indus river basin, particularly in the sukkur district, there is a critical need for accurate flood forecasting tools to account for local hydrological complexities. these complexities include variations in soil permeability, seasonal shifts in monsoon patterns, and the impact of upstream water management practices. these factors influence runoff behavior and water retention, making it challenging to accurately predict flood peaks and durations without detailed, localized calibration of the model. this study utilizes the hec-hms model to simulate rainfall-runoff processes in the region, focusing on calibrating the model to reflect real-world flood events [7]. the hydrologic engineering center’s hydrologic modeling system (hec-hms) was chosen for this study due to its ability to simulate complex rainfall-runoff processes in hydrologically diverse regions like the sukkur district. the specified hyetograph method was employed to input time-series rainfall data from the pakistan meteorological department (pmd) for a specific flood event [7]. this method enables accurate representation of real-life rainfall patterns over time, making it possible to calibrate the model against observed flood events [4]. given data constraints and the need for precise validation, this approach offered a practical solution for forecasting flood peaks and understanding basin response under extreme rainfall conditions [27]. by leveraging the specified hyetograph, the study ensured the simulation captured critical flood dynamics, providing a reliable tool for disaster management in the indus river basin [28]. this method was particularly suitable due to the limited availability of gridded or higher-resolution rainfall data and its effectiveness in improving model accuracy through direct comparison with observed hydrographs [29]. it also explains how this tool can support local disaster management efforts by utilizing topographic data, climate patterns, and regional soil characteristics. through this approach, it is expected that authorities in sukkur will gain valuable lead time for flood responses, thereby reducing the socio-economic impacts of seasonal floods in the area. the following section outlines the data collection process, model setup, and calibration techniques for achieving reliable flood predictions [30]. 2. methodology 2.1. data collection and preparation rainfall data for the sukkur district were primarily sourced from the pakistan meteorological department (pmd), where records covered multiple years and were provided with daily resolution. these raw datasets were reviewed for completeness and consistency, and obvious anomalies—such as uncharacteristically high or negative values—were investigated against records from nearby stations or reference data. any gaps identified during the initial examination were addressed through interpolation techniques or by supplementing missing records with information from regional re-analysis datasets. to ensure seamless integration with hec-hms, the final, cleaned rainfall time series was formatted as required by the software’s meteorological model component. discharge data for this study were obtained from gauging stations along the indus river at guddu, sukkur, and kotri, managed by the relevant provincial water authorities, including the irrigation department and the water and power development authority (wapda). while these stations provide critical data for the main channel, hydrological stations on tributaries were unavailable, potentially limiting the model’s ability to capture localized runoff dynamics from smaller catchments. the dataset includes both upstream and downstream measurements of river height asian review of environmental and earth sciences, 2025, 12(1): 14-27 19 © 2025 by the authors; licensee asian online journal publishing group (h) and discharge (q) at each station, recorded at regular six-hour intervals during the monsoon season of 2022. the sukkur gauging station, which serves as a critical monitoring point for flood management in the region, provided upstream and downstream discharge measurements essential for the calibration and validation of the hydrological model. flow values were systematically checked for anomalies by comparing observed discharges with expected ranges based on historical records and rainfall events. sudden spikes or inconsistencies in discharge data that did not correspond to significant rainfall events were flagged as potential errors and either corrected using available rating curves or excluded from the analysis. these discharge measurements were aligned with corresponding rainfall data from sukkur to allow for comprehensive analysis and hydrograph generation in hec-hms. the dataset also provided insights into the hydrological behavior of the indus river during extreme weather events, helping to highlight critical flood peaks and downstream flow propagation across the sukkur district. figure 4. average monthly precipitation for sukkur in 2022, based on daily observations from the pakistan meteorological department. while the annual total (~178 mm from monthly averages) appears low, the actual total rainfall for 2022 was 698.5 mm, with extreme shortduration rainfall events in july and august contributing to major flood events. figure 4 illustrates the average monthly precipitation for sukkur in 2022 based on daily observations from the pakistan meteorological department, highlighting that although the summed monthly averages (~178 mm) appear low, the true annual total reached 698.5 mm due to extreme short-duration rainfall events in july and august that triggered major floods. although figure 3 presents average monthly precipitation values, the data represents the year 2022 only, which included extreme rainfall episodes concentrated in short periods. the annual total for 2022 was 698.5 mm, with over 550 mm recorded during july and august alone. these conditions were sufficient to trigger widespread flooding in the region. figure 5. daily rainfall for sukkur during june to august 2022. the graph highlights the extreme rainfall variability during the monsoon season, with peak values exceeding 80 mm in a single day in august. these intense events played a critical role in the generation of surface runoff and flooding, despite a relatively low annual rainfall total. asian review of environmental and earth sciences, 2025, 12(1): 14-27 20 © 2025 by the authors; licensee asian online journal publishing group figure 5 illustrates the daily rainfall for sukkur from june to august 2022, highlighting extreme variability during the monsoon season, with individual daily totals exceeding 80 mm in august—intense events that drove surface runoff and flooding despite a relatively low annual rainfall total. 2.2. digital elevation model and watershed delineation the digital elevation model (dem) used in this study was derived from the shuttle radar topography mission (srtm) at a 30 m resolution, which offered sufficient detail for delineating sub-basins and stream networks within the sukkur district. dem processing was carried out in a geographic information system (gis) environment, where flow direction and accumulation grids were generated to identify drainage patterns. watershed boundaries, pour points, and relevant sub-basin divisions were then extracted, through arcgis. this delineation captured smaller tributaries contributing flow to the indus river to account for local runoff generation that might influence flood peaks in the main channel. the data collected from various sources forms the foundation of the hec-hms model setup. accurate rainfall and discharge data are essential to ensure the model reflects the hydrological realities of the sukkur district. figure 6. digital elevation model of sukkur. figure 6 illustrates the digital elevation model of the sukkur watershed, processed in arcgis from a 30 m srtm dataset, revealing the basin’s topographic relief and elevation gradients that govern surface runoff paths. dem data at 30-meter resolution was obtained from the shuttle radar topography mission (srtm). calibration and validation utilized historical flood events from 2010 to 2022, evaluated by nash-sutcliffe efficiency (nse), root mean square error (rmse), and percent bias (pbias). asian review of environmental and earth sciences, 2025, 12(1): 14-27 21 © 2025 by the authors; licensee asian online journal publishing group figure 7. watershed delineation of sukkur. figure 7 illustrates the watershed delineation of sukkur, showing the eight sub-basin boundaries and drainage network derived in arcgis from the 30 m srtm digital elevation model. flow accumulation-based subbasin classification within the modeled watershed. the color scheme represents ranges of flow accumulation values, indicating the relative volume of upstream contributing cells within the dem. these values are unitless and are used to define flow direction and watershed structure in the hydrological model. the colors do not correspond to subbasin area but to the accumulation threshold applied during stream and catchment delineation 2.3. hec-hms model setup 2.3.1. basin model configuration the hydrologic engineering center’s hydrologic modeling system (hec-hms) was used to create a comprehensive hydrological model for the sukkur district. the setup involved several key steps to ensure accurate representation of the basin and flood behavior. the basin model was initially created using arcgis for accurate spatial delineation. the basin boundaries were imported into hec-hms from arcgis, ensuring that all relevant sub-basins, stream networks, and outlet points were accurately captured. the sub-basin was connected to a designated outlet point. the outlet point represented the last confluence in the hydrological network before water exits the study area. the choice of outlet point versus ridge delineation was carefully considered to ensure accurate asian review of environmental and earth sciences, 2025, 12(1): 14-27 22 © 2025 by the authors; licensee asian online journal publishing group flow accumulation within each sub-basin. for the sub-basin, specific methods were chosen to simulate hydrological processes. the methods used included the initial and constant method for loss estimation, the scs unit hydrograph method for runoff transformation, and the constant monthly method for baseflow estimation. these methods were selected based on the availability and quality of data. figure 8. a) initial and constant method b) scs unit hydrograph c) constant monthly method. (all of the values are fetched by from the hec hms manual). figure 8 illustrates (a) the initial and constant loss method, (b) the scs unit hydrograph, and (c) the constant monthly baseflow method, with all parameter values obtained from the hec-hms manual. asian review of environmental and earth sciences, 2025, 12(1): 14-27 23 © 2025 by the authors; licensee asian online journal publishing group alternative methods, such as the green-ampt or deficit constant methods, were not used due to limitations of data and the need for more detailed soil and land use information. the parameters selected for these methods were sourced from the hec-hms manual and adjusted according to the characteristics of the sukkur region. the scs unit hydrograph method was chosen due to its effectiveness in simulating rainfall-runoff processes in areas with limited data availability. 2.3.2. meteorological model the meteorological model for this study was developed in hec-hms to capture the temporal and spatial distribution of rainfall during the monsoon period of 2022. the specified hyetograph method was selected as the precipitation input method, which allows for direct input of time-series rainfall data for the region. rainfall data was collected from the pakistan meteorological department (pmd) for the sukkur district, and daily rainfall values were input into the model for the selected time period. this method was chosen due to data availability constraints, as it provided a practical approach to input observed rainfall data directly into the model without requiring complex spatial interpolation techniques. the specified hyetograph method ensured that the temporal variation of rainfall was accurately captured, aligning with the model's time window focused on the monsoon months (june 2022 to august 2022). by directly using observed rainfall data, the meteorological model provided a reliable input for generating hydrograph simulations for the sukkur district. the time-series rainfall data from pmd was used to simulate historical flood events. while some data inconsistencies were noted, the data was used to maintain uniformity across the model. the model specifically focused on simulating the flood event with the highest recorded peak discharge to validate the model’s accuracy in predicting extreme flood scenarios. the simulation was designed to focus on the monsoon period of 2022, capturing peak discharge levels and flood events throughout this timeframe. 2.3.3. control specifications control specifications were set in hec-hms to define the simulation timeframe and time step. a daily time step was used to capture rapid changes in rainfall intensity and corresponding runoff. the control specifications were configured to focus on the monsoon period of 2022, during which the region experienced significant rainfall events. the start and end dates were carefully selected to encompass the entire monsoon season, including both lead-in and lead-out times for stabilization. the outlet point, representing the last discharge point in the hydrological network, was a critical component of the model. it ensured that the cumulative flow from all subbasins was accurately captured and that the flood simulation reflected realistic flow dynamics. after setting up the basin model in hec-hms, it is crucial to calibrate the model parameters to match observed flood events. this ensures that the simulations accurately predict flood behavior in the region. 2.4. scalability the hec-hms model is widely used for hydrological simulations and can be applied to various geographic regions, making it a scalable tool for flood forecasting. while this study focuses on the sukkur district, the methodology can be adapted to other flood-prone areas with similar climatic and hydrological conditions. however, the model’s accuracy heavily depends on the availability of reliable input data, such as rainfall records, land use classifications, and streamflow measurements. in data-scarce regions, additional calibration techniques, including remote sensing and machine learning, may be required to improve predictions. future studies could explore how well the calibrated parameters from this study can be transferred to other basins in pakistan to assess the model’s broader applicability and effectiveness in different hydrological settings. 2.5. model calibration and validation calibration is a critical step in hydrological modeling, ensuring that the simulated runoff and discharge patterns closely match observed values. since hydrological responses vary significantly between regions, a localized calibration process was essential for improving the accuracy of the hec-hms model in the sukkur district. hydrological data were sourced from three-gauge stations along the indus river’s main channel: guddu (upstream), sukkur (central study area), and kotri (downstream). while tributary gauge stations were unavailable, the model implicitly accounted for tributary inflows through observed discharge data at sukkur. the indus river in this region is regulated by the guddu, sukkur, and kotri barrages, which divert flows into irrigation canals and attenuate flood peaks. calibration focused on replicating observed flood behavior under these regulated conditions. this involved adjusting key model parameters, such as initial loss and constant rate, to better reflect local rainfallrunoff relationships. given that the region experiences rapid surface runoff due to monsoon-driven rainfall, the calibration process focused on fine-tuning parameters to capture peak discharge levels effectively. the calibration was performed by comparing simulated hydrographs with observed flood data from the sukkur gauging station, ensuring that the model accurately represented flood behavior under real conditions, including the influence of dams on flood mitigation. the presence of dams was accounted for in the model to reflect their role in regulating river flow and reducing peak discharge during flood events. by adopting a localized calibration approach, the model was able to better simulate flood peaks and runoff volumes, making it a more reliable tool for flood forecasting in the region. calibration was performed by comparing simulated hydrographs against observed flows for selected monsoon events within the study period. these events were chosen based on data reliability and their representation of varying rainfall intensities. the hec-hms model was calibrated by adjusting key parameters to minimize discrepancies between observed and simulated hydrographs. calibration focused on the 2022 monsoon season, specifically the three major flood peaks at sukkur station: july 15 (380 m³/s), august 2 (450 m³/s), and august 20 (410 m³/s). the model was validated against observed discharge data at sukkur station, achieving a nash-sutcliffe efficiency (nse) of 0.92 for the august 2 peak. downstream validation at kotri station was limited by data gaps during extreme flows. this comparison allowed for a thorough assessment of the model’s accuracy in reflecting flood dynamics under varying conditions.in validation was performed using a separate dataset from different flood events. the model’s performance was evaluated using statistical measures such as nash-sutcliffe efficiency (nse) and root mean square error (rmse). the calibrated model demonstrated reasonable accuracy in reproducing observed hydrographs, particularly during the highest flood events recorded. by calibrating and validating the asian review of environmental and earth sciences, 2025, 12(1): 14-27 24 © 2025 by the authors; licensee asian online journal publishing group model based on sub-basin characteristics, the study ensured that the hec-hms setup was robust and could provide reliable flood forecasts for the sukkur district. 2.6. hydrograph simulation and analysis the model was simulated for a range of observed and hypothetical storm events, particularly on monsoon periods known to create significant flood hazards in interest. hec-hms output consisted of time-series hydrographs at major junctions, sub-basin outlets, and the main reaches of the indus river. from these hydrographs, peak flows were identified, the timing of the peaks was recorded, and total runoff volumes were calculated to provide a comprehensive view of watershed response. where observed data were available, simulated hydrographs were compared against measurements to verify event timing and magnitude. in cases where design storms or hypothetical scenarios were modeled, the storms were derived using regional intensity-durationfrequency (idf) curves to represent varying rainfall intensities across different return periods. results were interpreted in the context of flood risk assessments, with particular attention to high-flow periods associated with exceedance probabilities of [e.g., 10%, 1%, and 0.5%], which were highlighted as critical intervals for water management decisions. 3. results and discussions the hec-hms model simulation for the sukkur sub-basin provided valuable insights into how rainfall turned into runoff during the 2022 monsoon season. according to the model, the peak discharge reached 450 m³/s on august 2, 2022, at midnight, with a total runoff volume of 1906 million cubic meters (mm). the model also showed that it took about 18 hours from the start of the rainfall event for the floodwaters to reach their highest point. looking at the hydrograph, we can see a steady increase in discharge leading up to the peak, which happened right after the heaviest rainfall in august. this suggests that the basin responds quickly to intense monsoon rains, which is a common trend in flood-prone areas of pakistan. the fact that the model successfully captured this pattern means it could be a reliable tool for flood prediction. the 450 m³/s peak discharge recorded in the model aligns well with the monsoon rainfall trends observed in the region. this further proves that the hec-hms model is well-suited for forecasting floods in places like sukkur, where seasonal flooding is a recurring challenge. one of the biggest advantages of this model is that it can be used not just for analyzing past events but also for predicting future ones. by feeding real-time rainfall data into the system, authorities could get an early heads-up on possible floods, allowing them to issue timely warnings and put emergency plans into action. figure 9. a) hydrograph of the entire year. figure 9 illustrates the hydrograph of the entire year, showing the temporal variation in discharge and highlighting the seasonal flood peaks driven by monsoon rainfall. asian review of environmental and earth sciences, 2025, 12(1): 14-27 25 © 2025 by the authors; licensee asian online journal publishing group figure 9. b) summary table describing simulated flood discharge. figure 9b illustrates the summary table describing simulated flood discharge, presenting observed versus simulated peak discharges, timing errors, and key performance metrics (nse, rmse) for each analyzed flood event. figure 9. c) results from the sub basin. figure 9c illustrates the sub-basin results, showing each of the eight delineated areas’ simulated discharge contributions and highlighting spatial variability in runoff generation. figure 9. a) hydrograph of the outlet point b) summary table describing simulated flood discharge from the outlet point c) hydrograph of the sub basin d) summary table from the sub basin. figure 9d illustrates the summary table from the sub-basins, detailing each basin area, calibrated parameter values (e.g., curve number, lag time), and simulated versus observed discharge statistics. results from the sub-basin analysis indicate that the simulated runoff depth (0.5 mm) corresponds to basinaveraged rainfall excess, not direct water depth in the channel. the peak discharge of 400 m³/s reflects cumulative contributions from the entire catchment area during extreme rainfall events, amplified by rapid surface runoff due asian review of environmental and earth sciences, 2025, 12(1): 14-27 26 © 2025 by the authors; licensee asian online journal publishing group to low soil infiltration rates in the arid sukkur region. this disparity between runoff depth and discharge magnitude underscores the role of catchment size and rainfall intensity in flood generation 3.1. peak discharge and rainfall patterns the model results reveal a strong alignment between rainfall patterns and peak discharge. the highest rainfall intensities occurred in august 2022, which matches the model’s predicted peak discharge date of 2nd august 2022. this suggests that the specified hyetograph method used in the simulation is appropriate for capturing localized flood behavior in the sukkur sub-basin. the model results highlight the importance of accurate rainfall data input. the total rainfall recorded during june, july, and august 2022 was approximately 651.5 mm, with the majority occurring in july (175 mm) and august (379.5 mm), contributing significantly to flood generation during the monsoon period. however, the model assumes that rainfall is evenly distributed throughout each day, which could slightly alter the timing of the peak discharge if more granular (hourly) data were available. the alignment of the simulated peak discharge with the highest rainfall intensities in august 2022 underscores the model’s accuracy in predicting flood peaks. by incorporating real-time rainfall data into the specified hyetograph method, the model can be used to forecast peak discharges in future flood events, aiding in early warning systems and disaster preparedness. the results indicate that the hec-hms model effectively simulates flood behavior in the sukkur district, capturing peak discharge levels during significant rainfall events. the following discussion explores the implications of these findings for flood management and disaster risk reduction in the region. the hydrograph generated from the simulation provides actionable insights for flood management. the timing of the peak discharge, combined with rainfall forecasts, can help authorities anticipate critical flood periods and reduce the impact of flooding on vulnerable communities. the calibrated model achieved strong accuracy (nse=0.92), providing approximately 18 hours of prediction lead time, thus validating the model’s reliability. 3.2. implications for flood management the findings of this study have significant implications for flood management in the sukkur region. although the monsoon is an annual event, the timing, intensity, and spatial distribution of rainfall can vary significantly from year to year, making accurate peak discharge and runoff volume predictions essential for enhancing the preparedness and response capacity of local authorities. for example, during the 2022 monsoon season, unexpectedly intense rainfall in parts of sindh and balochistan led to catastrophic flooding, overwhelming existing infrastructure and exposing gaps in flood preparedness, even in regions accustomed to seasonal rains. using hechms for localized flood forecasting can enhance disaster preparedness, providing actionable insights for disaster risk reduction and resilience planning. by identifying the timing and magnitude of flood peaks, the model can assist policymakers in designing flood defenses and evacuation plans that mitigate the impact of future flood events. the results of the hec-hms model simulation are plausible given the historical flood events in the sukkur region. the peak discharge value of 450 m³/s aligns with recorded flood levels during the monsoon season, indicating that the model accurately simulates rainfall-runoff processes in the study area. 4. conclusions flood forecasting is crucial to disaster risk management, particularly in regions like the sukkur district in sindh, pakistan, where the indus river poses a significant threat during the monsoon season. by leveraging advanced hydrological modeling techniques and integrating local data, the study aims to provide a valuable tool for flood forecasting and management in the sukkur district. the potential applications of this work extend beyond the immediate study area, offering insights and methodologies that could benefit flood management efforts throughout south asia's flood-prone regions. this study utilized the hec-hms model to simulate rainfall-runoff processes and assess flood risk in the district, providing valuable insights into flood behavior and mitigation strategies. the findings indicate that localized hydrological models can play a vital role in improving the accuracy and timeliness of flood predictions, allowing authorities to implement proactive measures to protect vulnerable communities. the study confirms hec-hms effectively forecasts floods with nse=0.92, providing an 18-hour advance warning specifically for sukkur. future studies should integrate real-time data to further improve forecast accuracy. the research demonstrates that integrating historical rainfall data, topographic features, and soil characteristics can significantly enhance the predictive capabilities of hydrological models. the hec-hms simulations highlighted the temporal and spatial distribution of rainfall and discharge, particularly during the critical monsoon months, offering a clear understanding of regional flood patterns. the results shows that the peak discharge in the sukkur region corresponds with high-intensity rainfall events, particularly in august, emphasizing the need for targeted flood mitigation strategies during the investigation period. this study also highlights the importance of improving data accuracy for more reliable model outputs. in conclusion, the application of the hec-hms model in the sukkur district provides a practical framework for flood forecasting and disaster risk reduction in flood-prone regions of pakistan. the insights from this research can help policymakers and local authorities make informed decisions to mitigate flood risks and improve community resilience. as climate change continues exacerbating extreme weather events, investing in localized hydrological models and real-time data integration is imperative to manage future flood risks in south asia better. references [1] t. tingsanchali, "urban flood disaster management," procedia engineering, vol. 32, pp. 25-37, 2012. [2] federal flood commission, "annual flood report," ministry of water and power, government of pakistan, 2012, 2012. [3] atta-ur-rahman and a. n. khan, "analysis of flood causes and associated socio-economic damages in the hindukush region," natural hazards, vol. 59, no. 3, pp. 1239-1260, 2011. [4] c. cahyono and w. k. adidarma, "influence analysis of peak rate factor in the flood events’ calibration process using hec–hms," modeling earth systems and environment, vol. 5, pp. 1705-1722, 2019. [5] a. ali, "indus basin floods: mechanisms, impacts, and management," 2013. retrieved: https://www.adb.org/sites/default/files/publication/30431/indus-basin-floods.pdf?utm_source=chatgpt.com. 2013. https://www.adb.org/sites/default/files/publication/30431/indus-basin-floods.pdf?utm_source=chatgpt.com asian review of environmental and earth sciences, 2025, 12(1): 14-27 27 © 2025 by the authors; licensee asian online journal publishing group [6] h. najafi et al., "high-resolution impact-based early warning system for riverine flooding," nature communications, vol. 15, no. 1, p. 3726, 2024. [7] n. kamuju, "a study on estimation of rainfall-runoff simulation accuracy for rihand catchment with remote sensing data using physically based semi-distributed hec-hms model," international journal of scientific engineering and research, vol. 12, no. 1, pp, 1-11, 2024. [8] s. k. dost, "disaster risk management plan sindh province," provincial disaster management authority, sindh. sindh, pakistan. encyclopædia britannica, inc.: the desert areas. encyclopædia britannica, 2008. [9] j. p. syvitski and g. r. brakenridge, "causation and avoidance of catastrophic flooding along the indus river, pakistan," gsa today, vol. 23, no. 1, pp. 4-10, 2013. [10] p. m. james and g. syvitski, robert brakenridge causation and avoidance of catastrophic flooding along the indus river. pakistan: gsa, 2013. [11] m. a. mukhtar et al., "analysis of canal discharge management through remodeled structure at guddu barrage," discover applied sciences, vol. 6, no. 6, p. 307, 2024. [12] m. s. hussain and s. lee, "investigation of summer monsoon rainfall variability in pakistan," meteorology and atmospheric physics, vol. 128, pp. 465-475, 2016. [13] m. arsalan, "urban development strategy for sukkur city, sindh, pakistan: a step towards visionary planning and development," pakistan journal of science, vol. 67, no. 1, pp. 120–126, 2015. [14] h. hasan, m. z. u. r. hashmi, s. i. ahmed, and m. anees, "assessing climate sensitivity of the upper indus basin using fully distributed, physically-based hydrologic modeling and multi-model climate ensemble approach," scientific reports, vol. 15, no. 1, p. 4109, 2025. [15] a. nusrat et al., "plausible precipitation trends over the large river basins of pakistan in twenty first century," atmosphere, vol. 13, no. 2, p. 190, 2022. [16] y. ma, x. hu, y. chen, z. hu, t. feng, and g. feng, "different characteristics and drivers of the extraordinary pakistan rainfall in july and august 2022," remote sensing, vol. 15, no. 9, p. 2311, 2023. [17] m. a. u. r. tariq and n. van de giesen, "floods and flood management in pakistan," physics and chemistry of the earth, parts a/b/c, vol. 47, pp. 11-20, 2012. [18] t. r. petty, n. noman, d. ding, and j. b. gongwer, "flood forecasting gis water-flow visualization enhancement (wave): a case study," journal of geographic information system, vol. 8, no. 06, pp. 692-728, 2016. [19] c. wu, g. huang, h. yu, z. chen, and j. ma, "impact of climate change on reservoir flood control in the upstream area of the beijiang river basin, south china," journal of hydrometeorology, vol. 15, no. 6, pp. 2203-2218, 2014. [20] b. g. tassew, m. a. belete, and k. miegel, "application of hec-hms model for flow simulation in the lake tana basin: the case of gilgel abay catchment, upper blue nile basin, ethiopia," hydrology, vol. 6, no. 1, p. 21, 2019. [21] a. hamdan, a. naseh, s. almuktar, and m. scholz, "rainfall-runoff modeling using the hec-hms model for the al-adhaim river catchment, northern iraq," hydrology, vol. 8, no. 2, p. 58, 2021. [22] x. sun, k. jin, h. tao, z. duan, and c. gao, "flood risk assessment based on hydrodynamic model—a case of the china–pakistan economic corridor," water, vol. 15, no. 24, p. 4295, 2023. [23] b. naeem et al., "flood hazard assessment for the tori levee breach of the indus river basin, pakistan," water, vol. 13, no. 5, p. 604, 2021. [24] m. u. nadeem et al., "application of hec-hms for flood forecasting in hazara catchment pakistan, south asia," international journal of hydrology, vol. 6, no. 1, pp. 7-12, 2022. [25] i̇. b. peker, s. gülbaz, v. demir, o. orhan, and n. beden, "integration of hec-ras and hec-hms with gis in flood modeling and flood hazard mapping," sustainability, vol. 16, no. 3, p. 1226, 2024. [26] a. m. al-areeq, m. a. al-zahrani, and h. o. sharif, "the performance of physically based and conceptual hydrologic models: a case study for makkah watershed, saudi arabia," water, vol. 13, no. 8, p. 1098, 2021. [27] x. yu and j. zhang, "the application and applicability of hec-hms model in flood simulation under the condition of river basin urbanization," water, vol. 15, no. 12, p. 2249, 2023. [28] j. c. cacal, v. c. a. austria, and e. b. taboada, "extreme event-based rainfall-runoff simulation utilizing gis techniques in irawan watershed, palawan, philippines," civil engineering journal, vol. 9, no. 1, pp. 220-232, 2023. [29] m. b. gunathilake, p. panditharathne, a. s. gunathilake, and n. warakagoda, "application of a hec-hms model on event-based simulations in a tropical watershed," engineering and applied science research, vol. 47, no. 4, pp. 349-360, 2020. [30] s. j. mousavi, k. c. abbaspour, b. kamali, m. amini, and h. yang, "uncertainty-based automatic calibration of hec-hms model using sequential uncertainty fitting approach," journal of hydroinformatics, vol. 14, no. 2, pp. 286-309, 2012. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 30 © 2021 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 8, no. 1, 30-37, 2021 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/journal.506.2021.81.30.37 © 2021 by the authors; licensee asian online journal publishing group assessment of photosynthetic pigments and dust load in selected avenue plants of saharanpur and herbertpur areas of india abid qadir1 arshad bhat2 iqra qureshi3 ( corresponding author) 1research scholar, department of environmental studies, the glocal university, india. email: abidqadir12@gmail.com tel: +91-7006259141 2post-doctoral research associate, rajiv gandhi chair in contemporary studies on livelihood and food security, sher-e-kashmir university of agricultural sciences and technology of kashmir. email: bhatarshad09@gmail.com tel: +91-9797268144 3young professional, department of food technology, central institute of temperate horticulture, rangreth srinagar. email: iqraqureshi840@gmail.com tel: +91-7006276101 abstract the paper depicts impact of so2, no2, ozone and co in chosen road plants of saharanpur and herbertpur regions in indian dominion. plant species falling in and around the area of modern territory and street side were chosen for examining purpose. different morphological attributes and impact of business and vehicular residue on chlorophyll shade were contemplated and noticed the impact of residue molecule on development of the plant species (ficus religiosa, mangifera indica). in the examination the impacts of residue on chosen tree species was noticed and which will help in overseeing advancement of green belt to lessen the air contamination in the investigation area. treatment with dust fundamentally expanded the fixation on leaves and the impacts were more extreme in significant degree of residue medicines. contrasted with control, chlorophyll and porphyrin in substance were essentially diminished in the residue treated gatherings. this investigation propounds that business and vehicular residue statements affect photosynthetic shades, with broad impacts on development and improvement of plant. keywords: assessment, chlorophyll, photosynthesis, pollution, pigmentation, dust load, impact. citation | abid qadir; arshad bhat; iqra qureshi (2021). assessment of photosynthetic pigments and dust load in selected avenue plants of saharanpur and herbertpur areas of india asian review of environmental and earth sciences, 8(1): 30-37. history: received: 21 june 2021 revised: 23 july 2021 accepted: 18 august 2021 published: 14 september 2021 licensed: this work is licensed under a creative commons attribution 3.0 license publisher: asian online journal publishing group acknowledgement: all authors contributed to the conception and design of the study. funding: this study received no specific financial support. competing interests: the authors declare that they have no conflict of interests. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study was reported; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study follows all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 31 2. methodology ..................................................................................................................................................................................... 31 3. results and discussion ................................................................................................................................................................... 33 4. conclusion ......................................................................................................................................................................................... 37 references .............................................................................................................................................................................................. 37 mailto:abidqadir12@gmail.com mailto:bhatarshad09@gmail.com mailto:iqraqureshi840@gmail.com http://creativecommons.org/licenses/by/3.0/ http://creativecommons.org/licenses/by/3.0/ https://www.doi.org/10.20448/journal.506.2021.81.30.37 https://orcid.org/0000-0002-3423-7554 https://orcid.org/0000-0002-9689-2351 https://orcid.org/0000-0003-4314-2132 asian review of environmental and earth sciences, 2021, 8(1): 30-37 31 © 2021 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study contributes to existing literature by assessing and estimating dirt load on leaf floor of flowers of ficus religiosa, mangifera indica through dirt taking pictures potential of road plants of saharanpur metropolis and herbertpur and also assess effect of pollutants on photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids). the paper will of immense help for the policy makers and planners to reduce the emission of dust particulates from the industries and the vehicular transport around the study area, and will further opens a gateway for the researchers to study impact of dust on the aquatic and terrestrial animals. 1. introduction metropolitan air contamination has become a genuine natural issue for trees and other living habitats (chauhan & joshi, 2008). the vast majority of indian urban areas are influencing with the presence of high centralizations of poisonous vaporous and particulate toxins because of industrialization, gravely kept up helpless streets, helpless support of vehicles, employments of powers with poor natural execution and absence of mindfulness (joshi & chauhan, 2008). encompassing air contamination in a few huge urban communities of india is among the most noteworthy on the planet (agrawal, 2005). as per a gauge, dust contaminations involve around 40% of absolute air contamination issue in india (chauhan, 2008). in city locales assorted kinds of contamination alongside sox, nox, ozone (o3), carbon monoxide and dangerous characteristic mixtures are dispatched on account of those anthropogenic exercises, which can be delivering a ruinous effect on vegetation. contamination is a significant problem influencing the world. it is accessible in masses of structures which incorporate air, land, and water contaminations and structures a few reasserts which incorporate industry, business, and transportation here and there you may see it, anyway various sorts are imperceptible to the uncovered eye. the particulates and vaporous contaminations, alone and in blend, can make genuine mishap the general physiology of plants (anda, 1986; ashenden & williams, 1980; mejstřík, 1980; seinfeld, 1975). it has been accounted that vaporous structures are consumed by the leaves, while the particulate structures are assimilated through the external surface of the plants. influenced plants shows some regular impacts like chlorophyll, corruption, restraint in photosynthesis and diminishing plant development (davison & blakemore, 1976). plant reaction to air contamination can be utilized to evaluate the nature of air that may give early admonition signs of air contamination patterns (wagh, shukla, tambe, & ingle, 2006). plants tremendous give a huge leaf region to impingement, ingestion and amassing of air poisons to diminish the contamination level noticeable all around climate (escobedo et al., 2008), with a different degree for various species (hove, bossen, de bok, & hooijmaijers, 1999). unfavorable impacts of air toxins on plants with decrease in photosynthetic shades and yield have been appeared by changed laborers in various harvests (davison & blakemore, 1976; farmer, 1993; lerman, 1972; meyerowitz et al., 1987; rajput & agrawal, 2005; saquib & khan, 1999) air contaminations has been characterized as an additional tension on vegetation given that they every now and again answer to air disease with inside the equivalent way as they answer to dry spell and distinctive environmental factors air toxins has outrageous results at the human wellbeing. contingent upon the degree of exposure and the type of toxin exhaled in, those results can shift, beginning from simple signs like hacking and the contamination of the breathing parcel to intense circumstances like bronchial hypersensitivities and chronic lung illness. it in this back drop the present study was carried out to study the negative effects of dust deposition on photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids) and on leaf surface. 2. methodology for the analysis purpose, saharanpur and herbertpur were taken as unit of analysis figure 1 & 2. figure-1 & figure-2. map of herbertpur & saharanpur (site 1& 2). 2.1. site selection on the idea of excessive site visitor’s zone, excessive dust generating supply and plant variety following sites had been decided on: • site-1 herbertpur (dehradun). • site-2 saharanpur city (uttar pradesh). site 1: asian review of environmental and earth sciences, 2021, 8(1): 30-37 32 © 2021 by the authors; licensee asian online journal publishing group • herbertpur is a city and a nagar panchayat in dehradun district with inside the indian country of uttarakhand. it is positioned at the financial institution of river asan and the call of the vicinity is at the call of sir herbert the antique call of herbertpur is chuodpur. it is positioned at 30.450n it has a median elevation of 427 meters (1,401 feet). nhw passes thru vikasnagar. it ends in yamunotri. there is large site visitors rush on this region because of chandigarh dehradun toll road heaps of cars are strolling on this region everywhere in the day. site 2: • saharanpur city (district) is the north maximum a part of uttar pradesh, india and is near the foothills of shivalik range. it lies in the northern a part of doab region. it is an agricultural predominant region. saharanpur is located at 29.970n 77.550e, approximately a hundred thirty km south-southeast from chandigarh and a hundred and seventy km north-northeast from delhi. it has a median elevation of 284 meters. it is fantastically polluted and densely populated because of the human beings dwelling there. there are considerable numbers of factories which might be the reason of highest pollutants there. the motion of site visitors is so excessive, this is the reason for highest polluted surroundings there. 2.2. identification of important dust arresting plant indicator species the identity of the plant species table 1 changed into undertaken at respective sites that have very excessive herbal ability of particulates and dust debris from ambient air close to creation regions and at excessive site visitor’s junctions with vehicle motion due to their morphological and anatomical. the identity of plant life changed into undertaken with the help of literature, monographs and taxonomical books. table-1. plant species decided on for study. s.no. botanical name common name family 1 mangifera indica mango anacardiaceae 2 saraca indica peepal moraceae 2.3. dust load dust is produced with the aid of using subdivision of strong cloth through mechanical movements or in nature. anthropogenic emission is generated in the course of grinding or milling of materials, in the course of switch of finely divided cloth in addition from agriculture, forestry and production activities. the massive the particle diameter, they generally tend to settle faster. particle massive than 50 µm settle rapidly. due to non-stop publicity of flora to dust debris, which gets deposited at the leaf floor and that is termed as ‘dust load’. dust load is calculated with the aid of using following components: dust load on leaf (in mg) dust load (in mg/cm2) = surface area of leaf cm2 2.4. plant’s leaf analysis the leaf samples from the chosen plant species of both sites were accumulated, washed well and weighed. morphological and biochemical traits of selected plant species were carried out by following popular procedures. 2.4.1. morphological analysis morphological characters like forms of leaves, association of leaves, floor and texture of leaves, form and length of leaves were observed. 2.4.2. biochemical analysis 2.4.3. chlorophyll content reagent: 80% aetone (v/v) chilled: chlorophyll estimation was carried out with the aid of using arnon approach. for this 0.1 gm. leaf pattern was beaten in 5ml of 80% acetone (chilled) after which centrifuged at 10,000rpm for 10 minutes. pallets was discarded and supernatant was taken out. absorbances were taken at 480nm, 510nm, 645 and 663nm. acetone was used as blank. various concentrations in mg g-1fr, wt. was calculated with the aid of the subsequent formulae given by maclachlan and zalik (1963) for chlorophyll: chlorophyll a (mg g-1 f. w) = 12.7 (𝐴663)− 2.63(𝐴645)×𝑣 𝐷×(1000)×𝑊 chlorophyll b (mg g-1 f. w) = 22.9 (𝐴645)− 4.68 (𝐴663)×𝑣 𝐷 ×(1000)×𝑊 total chlorophyll (mg g-1 f.w) = chlorophyll a + chlorophyll b the carotenoid content material was predicted by usage of the formulae of duxbm'y and yentsch (1956) carotenoid (mg g-1f.w) = 7.6 (𝐴480)− 1.49 (𝐴510)×𝑣 𝐷 ×(1000)×𝑊 where, a = absorbance v = quantity of the pattern (ml) d = distance traveled with the aid of using the mild path (=1cm) w = weight of the leaf (g) 2.4.4. leaf dust accumulation newly matured leaves of the chosen tree species were taken for recording their dust load. the higher surfaces of the leaves were wiped with exceptional brushes which were later tagged for identification. the leaves were stored for twenty-four hours for dust accumulation. after 24 hours leaf dust turn was collected within the pre weighed butter paper baggage with the help of high-quality brush. after taking the statistics for dust accumulation, the leaves were lessen from petiole, saved in ice field and brought to the laboratory for further analysis. the asian review of environmental and earth sciences, 2021, 8(1): 30-37 33 © 2021 by the authors; licensee asian online journal publishing group amount of dust collected on leaves was weighed on top pan virtual balance and calculated with the help of following equation: w = 𝑾𝟐−𝑾𝟏 𝑨 where; w = dust content material (gm-2) w1 = initial weight of butter paper bag w2 = final weight of butter paper bag with dust a = widespread location 3. results and discussion 3.1. determination of dust load in selected plants the dust trapping ability of plant life were taken as a parameter for enhancing and tracking air quality. by calculating dust load on plant life were categorized into unique classes like excessive dust ability, mild dust shooting ability and occasional dust shooting ability. this categorization of plant life in keeping with their performance of shooting dust is beneficial in choice of road plant life in selected site covers of saharanpur. it changed into a business in addition to excessive site visitor’s vicinity. the variety of heavy cars in step with day is greater compared to different regions because of chandigarh, dehradun highway. pollution density was highest their because of heavy site visitors. these are the most important reason of pollutants on this vicinity. selected site (s1) covers herbertpur. this is a place that's much less polluted than saharanpur. because there is much less motion of site visitors there and additionally there is much less variety of creation locations there. the plant whose layout shown in table 2 is usual place at each decided on sites. among those plant life species the most dust load changed into recorded with the aid of using ficusreligiosa tree than mangiferaindica tree at each sites. the results revealed that saharanpur site changed into greater polluted than herbertpur site, because of heavy site visitor’s motion and establishment of industries in the area. the results further revealed that the ficusreligiosa tree captures greater dust than mangiferaindica tree figure 3 & 4. table-2. dust load (mg/cm2) of selected plant species at both sites. sites herbertpur (s1) saharanpur (s2) r1 r2 r3 r4 r1 r2 r3 r4 0.015 0.275 0.055 0.01 0.03 0.00 0.06 0.00 0 0.025 0.25 0.11 0.02 0.055 0.375 0.035 0.05 0.05 asian review of environmental and earth sciences, 2021, 8(1): 30-37 34 © 2021 by the authors; licensee asian online journal publishing group figure-3. dust deposition on peepal plants at two different sites. figure-4. dust deposition on mango plants at two different sites. peepal tree >mango tree: a superb correlation has been observed among the dust trapping and micro roughness of the full leaf vicinity. roughness of top floor may be described because of presence of ridges and asian review of environmental and earth sciences, 2021, 8(1): 30-37 35 © 2021 by the authors; licensee asian online journal publishing group furrows fashioned with the aid of using epidermal mobileular lining, vein projections, stomata included with wax rings, cuticular arches, hairs or scales and sunken position. mangiferaindica (mango tree) is called flowering plant in sumac and poison ivy own circle of relatives anacardiaceae. it is a big fruit tree, able to developing a top and crown width of approximately 30 meters and trunk circumference of greater than 3.7 meters. it is likewise a terrible species for dust trapping. the leaf of mango tree is lengthy and narrow. thus this parameter fails to make it an awesome species for dust loading. hence it must be planted in such vicinity in which dust pollutants are much less like in parks and gardens. ficusreligiosa (peepal tree) recognized for non-secular purpose. they are lengthy and huge trees. it is a great specie for dust trapping. the leaves of peepal tree are very huge figure 5. therefore, with these characteristics, such species are ideal for trapping of dust. hence it must be planted close to the roads and on locations in which pollutants stage is excessive. figure-5. dust deposition on common selected plants at two different sites. 3.2. leaf surface morphology 3.2.1. structure of leaf i. structure of leaf lamina: unique kinds of leaves tend to have qualification in various components in their surfaces. a few kinds of leaves have additional floor pressure or harshness than various leaves, which can likewise affect tenacity or molecule solvency. the various diverse morphological capacities are components obligated for dust shooting wonders through methods for leaves table 3. table-3. morphological characters of leaves of selected plant species. plants leaf habit leaf surface lamina shape + margin lamina apex venation phyllotaxy m.indica tropical broad, rounded. flat, lateral, entire, undulate, smooth acute reticulate alternate f.religiosa deciduous glabrous, glaucou, fleshy oval or elliptical, entire blunt reticulate opposite leaves may be of various shapes, sizes and might have specific sorts of surfaces and textures. larger the vicinity extra dust could be attenuated at the floor. venation may be defined because the association of veins in a leaf. phyllotaxy is the association of the leaf at the stem. there are a number of essential traits which can supply a clue which plant species may be used for development of air-exceptional of surroundings and environment. ii. length and breadth of leaf and petiole: size, shape, texture and floor of leaves play a completely essential function in dust shooting mechanism. larger the leaf vicinity more could be its performance to seize dust. the above desk indicates that mangiferaindica and ficusreligiosa are having pretty big in comparison to other plants. due to big floor vicinity of those plants, they are taken into consideration as best road plants. due to big floor vicinity of leaves of those plants, they are taken into consideration to be beneficial in enhancing air-exceptional like bargad tree table 4. hairs gift at the leaf floor allows dust debris to paste on it, consequently on this manner leaf adsorbs dust and contributes in discount of dust pollution. table-4. length and breadth of selected plants and leaves. plant selected length of leaf (in cm) length of petiole (in cm) breadth of leaf (in cm) mangifera indica 24 1 4.2 ficus religiosa 18.2 1 10.6 asian review of environmental and earth sciences, 2021, 8(1): 30-37 36 © 2021 by the authors; licensee asian online journal publishing group 3.2.2. biochemical analysis i. chlorophyll content: chlorophyll is a pigment observed inside the cells of leaves that is shaped simplest in the presence of mild and is the substance that shades plant life green, chlorophyll is contained in chloroplasts and has the belongings of taking pictures mild power. chlorophyll molecules are mainly organized in and round picture graph structures which are embedded with inside the thylakoid membranes of chloroplasts. in those complexes serves number one functions. the characteristic of the sizable majority of chlorophyll (as much as numerous hundred molecules according to photosystem) is to take in mild and switch that mild power through resonance power switch to a selected chlorophyll pair inside the response middle of the photosystem. the presently universal photosystem gadgets are photosystem i and photosystem ii, that have their personal wonderful response middle chlorophylls, named p680 and these pigments are named after the wavelength (in nanometers) of their red-top absorption most. these pigments are referred to as accent pigments or chlorophyll ‘a’ and chlorophyll ‘b’. the identity, characteristic and spectral residences of the varieties of chlorophyll in every photosystem are wonderful and decided through every different and the protein shape surrounding them. carotenoids are tetraterpenoid natural pigments which are obviously taking place inside the chloroplasts and chromoplasts of plant life. there are over six hundred acknowledged carotenoids, they were break up into classes, xanthophylls (which include oxygen) and carotenes which might be only hydrocarbons, and include no carotenoids in widespread take in blue mild. they serve key roles in plant life, they take in mild power to be used in photosynthesis, and that they defend chlorophyll from picture graph damage. the photosynthetic pigment content materials on plant life at sites are estimated in table 5. table-5. chlorophyll a (mg g-1f.w) content in sampled leaves. plant species sites site 1 site2 r1 r2 r3 r4 r1 r2 r3 r4 mangifera indica 0.018 0.055 0.038 0.048 0.066 0.080 0.045 0.040 ficus religiosa 0.058 0.093 0.075 0.045 0.062 0.076 0.040 0.078 the chlorophyll content material of site1 is observed to be greater than site 2 which became uncovered to dust. the reducing order of chlorophyll and carotenoid content material on sites are offered below: site 1 < site2 it may be due to the motive that site 2 is more populated as it is a business place and there site visitors may be very excessive compared to site1, that is why the plant life on this place has greater chlorophyll content material compared to site 2. at site 2, the most general chlorophyll content material became recorded in ficusreligiosa accompanied through mangiferaindica. it suggests that ficus religiosa (peepal) are pollutants tolerant species. same sample of end result has been recorded at different site table 6. table-6. chlorophyll b (mg g-1f.w) content in sampled leaves plant species sites site 1 site 2 r1 r2 r3 r4 r1 r2 r3 r4 mangifera indica 0.031 0.038 0.052 0.083 0.116 0.069 0.067 0.054 ficus religiosa 0.098 0.047 0.139 0.104 0.105 0.055 0.057 0.141 it has been recorded that dust deposition influences photosynthetic pigments adversely. researchers have recorded discount in chlorophyll content material beneath air pollutants; the shading consequences, because of deposition of suspended particulate count at the leaf floor is probably accountable for this lower with inside the awareness of chlorophyll in polluted place. they additionally pronounced discount carotenoid in plant life beneath air pollutants. chloroplast pigments have been proven to be very touchy to diverse environmental influences. changes in chlorophyll and carotenoid content material have been investigated through numerous researchers. this is possible due to deceleration of the biosynthetic techniques as opposed to chlorophyll ‘a’. in the present analysis it is observed that chlorophyll ‘a’ content material of leaves became better than chlorophyll ‘b’ at selected sites. reduced chlorophyll ‘b’ content material compared to chlorophyll ‘a’ confirmed that chlorophyll ‘b’ is greater touchy than chlorophyll ‘a’. the table 7 shows total chlorophyll content in both the sites. carotenoid content material is reporting better at site 1 compared to site 2. in site 1 it is far most in ficusreligiosa accompanied through mangiferaindica and identical sample of end result has been recorded at site 2 table 8. table-7. total chlorophyll (mg g-1f.w) content in sampled leaves. plant species sites site 1 site 2 r1 r2 r3 r4 r1 r2 r3 r4 mangifera indica 0.049 0.093 0.090 0.131 0.182 0.149 0.112 0.094 ficus religiosa 0.156 0.14 0.214 0.149 0.167 0.131 0.097 0.219 table-8. carotenoid (mg g-1f.w) content in sampled leaves. plant species sites site 1 site 2 r1 r2 r3 r4 r1 r2 r3 r4 mangifera indica 0.030 0.046 0.009 0.057 0.050 0.067 0.057 0.062 ficus religiosa 0.069 0.059 0.034 0.062 0.014 0.017 0.061 0.024 asian review of environmental and earth sciences, 2021, 8(1): 30-37 37 © 2021 by the authors; licensee asian online journal publishing group 4. conclusion an extensive misfortune in all out chlorophyll in the leaves of plants presented to contamination upholds the contention that the chloroplast is the essential site of assault via air contaminations like so2, no2, ozone and co. this examination shows that openness to particulate statement modify the plant development without changing any actual changes to the plant. reaction of plants towards air is being surveyed via air contamination resilience record. some plant species and assortments are delicate to such an extent that they can be advantageously utilized as natural pointers or on the other hand screens of explicit toxins. other than concentrate on sway of mechanical residue particles on chlorophyll color of leaves, further exploration is going on different boundaries to know the air pollution tolerant lists of the plants here which can additionally help organizer in dealing with the metropolitan urban areas by creating green belt advancement to decrease the air contamination. taking everything into account, the particulate contamination at various chosen regions was essentially because of development work, mechanical work and vehicles. biochemical boundaries like chlorophyll 'a' chlorophyll 'b' & carotenoids in chosen plants were determined, these boundaries are considered as contamination markers. assessment of these boundaries assumes a significant part in demonstrating the degree of residue contamination. references agrawal, m. (2005). effects of air pollution on agriculture: an issue of national concern. national academy science letters, 28(3/4), 93-106. anda, a. (1986). effect of cement kiln dust on the radiation balance and yields of plants. environmental pollution series a, ecological and biological, 40(3), 249-256. available at: https://doi.org/10.1016/0143-1471(86)90099-1. ashenden, t., & williams, i. (1980). growth reductions in lolium multiflorum lam. and phleum pratense l. as a result of so2 and no2 pollution. environmental pollution series a, ecological and biological, 21(2), 131-139. available at: https://doi.org/10.1016/01431471(80)90041-0. chauhan, a., & joshi, p. (2008). effect of ambient air pollution on photosynthetic pigments on some selected trees in urban area. ecology environment and conservations, 14(4), 23-27. chauhan., a. (2008). impact of dust pollution on photosynthetic pigments of some selected trees grown at nearby of stone-crushers. environment conservation journal, 9(3), 11-13. davison, a. f., & blakemore, j. (1976). in: mansfield ta (ed) effects of air pollutions on plants. cambridge university press: cambridge. davison, a. w., & blakemore, j. (1976). in: effects of air pollutions on plants (ed. t.a. mansfield). cambridge university press: bridge, uk. duxbm'y, a. c., & yentsch, c. s. (1956). plankton pigment nomographs, tecmlical report no. 54 the lignin fraction of marine sediments, by richard g. bader. office of naval research. project nr 083-012. university of vashington, departnent of oceinography seattle, 5, washington. escobedo, f. j., wagner, j. e., nowak, d. j., de la maza, c. l., rodriguez, m., & crane, d. e. (2008). analyzing the cost effectiveness of santiago, chile's policy of using urban forests to improve air quality. journal of environmental management, 86(1), 148-157. available at: https://doi.org/10.1016/j.jenvman.2006.11.029. farmer, a. m. (1993). the effects of dust on vegetation—a review. environmental pollution, 79(1), 63-75. available at: https://doi.org/10.1016/0269-7491(93)90179-r. hove, v. l., bossen, m., de bok, f., & hooijmaijers, c. (1999). the uptake of o3 by poplar leaves: the impact of a long-term exposure to low o3-concentrations. atmospheric environment, 33(6), 907-917. available at: https://doi.org/10.1016/s1352-2310(98)00259-3. joshi, p. c., & chauhan, a. (2008). performance of locally grown rice plants (oryza sativa l.) exposed to air pollutants in a rapidly growing industrial area of district haridwar, uttarakhand, india. life science journal, 5(3), 41-45. lerman, s. (1972). cement-kiln dust and the bean plant (phaseolus vulgaris l. black valentine var.) in-depth investigations into plant morphology, physiology and pathology. ph.d. dissertation, university of california. maclachlan, s., & zalik, s. (1963). plastid structure, chlorophyll concentration and free amino acid composition of a chlorophyll mutant of barley. candan journal of botany, 41(7), 1053-1062. available at: https://doi.org/10.1139/b63-088. mejstřík, v. (1980). the influence of low so2 concentrations on growth reduction of nicotiana tabacum l. cv. samsun and cucumis sativus l. cv. unikat. environmental pollution series a, ecological and biological, 21(1), 73-76. available at: https://doi.org/10.1016/01431471(80)90034-3. meyerowitz, a., olszyk, d. m., kats, g., dawson, p. j., wolf, j., & thompson, c. r. (1987). effects of so2 on physiology, elemental content and injury development of winter wheat. agriculture, ecosystems & environment, 20(1), 37-47. available at: https://doi.org/10.1016/0167-8809(87)90026-0. rajput, m., & agrawal, m. (2005). biomonitoring of air pollution in a seasonally dry tropical suburban area using wheat transplants. environmental monitoring and assessment, 101(1), 39-53. saquib, m., & khan, f. (1999). air pollution impacts on the growth and reproductive behaviour of mustard. journal of environmental biology, 20(2), 107–110. seinfeld, j. h. (1975). air pollution: physical and chemical properties. u.s.a: mc. graw hill. wagh, n., shukla, p. v., tambe, s. b., & ingle, s. (2006). biological monitoring of roadside plants exposed to vehicular pollution in jalgaon city. journal of environmental biology, 37(2), 419-421. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. 23 © 2022 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 9, no. 1, 23-33, 2022 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v9i1.4374 © 2022 by the authors; licensee asian online journal publishing group engineering structural strength properties of lateritic soil-cement mix for road pavement stability omowumi ademila department of earth sciences, adekunle ajasin university, akungba, akoko, nigeria. email: omowumi.ademila@aaua.edu.ng abstract qualitative construction materials in highway pavement prompted addition of cement at different proportion of 2 10% to lateritic soils for enhanced performance. engineering geological tests were performed on the soil-cement mixture to determine their highway pavement suitability for durable road construction. furthermore, modelling of the strength characteristics of the mixture presents the correlation between the structural properties and cement mix. thus, increase in soil-cement california bearing ratio (cbr) and unconfined compressive strength (ucs) values with higher cement mix of 8%, revealed enhanced soil improvement. the soil strength is also affected by the curing period. better quality strength characteristics obtained decreases pavement thickness with reduced cost in road construction. relationship between the soil strength properties and cement mix content are represented by polynomial model. this reveals stronger bearing capacity of soil cement mix cured in 14 days with r2 ≥ 0.8. the lateritic soil cement mix at 8% cement content could serve as highway subbase and base construction materials. cement mix having positive effects on soil geotechnical properties are indication of its effectiveness in enhancing volume stability of different soils. prolong curing time is essential for compacted soil cement mix for enhanced geotechnical engineering properties and to improve the quality of lateritic soil used as road construction materials. thus, cement-stabilized lateritic soil reduces cost of road construction, its persistent failure, human and environmental losses. keywords: crushed rock, curing period, highway construction, lateritic soil cement, soil improvement, structural properties. citation | ademila, o. (2022). engineering structural strength properties of lateritic soil-cement mix for road pavement stability. asian review of environmental and earth sciences, 9(1), 23– 33. 10.20448/arees.v9i1.4374 history: received: 12 october 2022 revised: 21 november 2022 accepted: 5 december 2022 published: 27 december 2022 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. competing interests: the author declares that there are no conflicts of interests regarding the publication of this paper. transparency: the author confirms that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 24 2. study area location and geology ................................................................................................................................................ 24 3. materials and study methods ....................................................................................................................................................... 24 4. results of study and discussion ................................................................................................................................................... 27 5. conclusion ......................................................................................................................................................................................... 33 references .............................................................................................................................................................................................. 33 mailto:omowumi.ademila@aaua.edu.ng https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v9i1.4374 https://orcid.org/0000-0001-5177-1110 asian review of environmental and earth sciences, 2022, 9(1): 23-33 24 © 2022 by the authors; licensee asian online journal publishing group contribution of this paper to the literature: this study unravels the intrinsic reasons for failure of engineering structures constructed with lateritic soil prior the expiration of the design age. the soil inconsistent engineering properties necessitated its stabilization with cement for improved quality soil suitable for durable and sustainable road pavement construction. bearing capacity of the soil-cement mix improved with prolong curing time. 1. introduction construction of civil engineering works on geomaterials (soil or rock) dictates its structural performance. soils support structures, pavement for highways, airport and dams. some existing soils may be used in their natural state, while others may require stabilization which modifies its engineering properties, producing better breed of construction materials capable of meeting the specific requirements. lack of standard construction materials has necessitated the search for local alternatives. in tropical and subtropical areas, lateritic soils rich in aluminium, iron appear as surface soil deposits formed from physical and chemical weathering of pre-existing rocks. laterites in nigeria serve as foundation materials in construction of civil engineering works without due consideration to its geotechnical behaviour and site performance. poor subsoil engineering structural characteristics accounts for unstable highway sections in nigeria [1]. the inconsistency of soil engineering properties prompted consistent soil test for update subsoil information to establish the most suitable soil stabilization method prior highway design and construction. utilization of soils for a particular purpose depends on factors affecting their performance and in-depth knowledge of their geotechnical properties. engineering structures constructed with lateritic soil experience failure before the expiration of the design age and this has necessitated soil stabilization for quality soil. commonly used additives to enhance soil quality are lime, cement, fly ash, cement kiln dust, rock flour and other forms of stabilizers. clay swells in water, shrinks when dry and thrives in freezing conditions. this makes them unnoticeable when used [2]. most lateritic soils contain high proportion of clay, thus, their properties should be improved. soil modification requires different methods of improving engineering performance of soil for suitability for different construction purposes. cement and lime are major additives for improving granular and fine-grained soils, weak/soft soils, problematic soils and generally poor properties soils. despite this, the use of cement as a stabilizer is well-known than lime due to factors of its availability, cost and strength that are attainable using cement. higher strength is attained using cement than using the same quantity of lime [3]. recently, in an attempt to achieve an economically effective modification of deficient soils, available locally generated waste materials are utilized to strengthen weak soil for appropriate performance. this form of soil stabilization emphasizes best use of local materials to minimize civil engineering construction cost as well as reducing the environmental hazards they cause. however, most of these materials do not have adequate cementation property required to bind the materials to an acceptable performance for sustainable road pavements as cement. hydration reaction associated with cement enables the improvement of soil properties. soil and rocks, under load beyond their bearing capacity fail [4]. natural resources depletion as a result of consistent exploration has prompted the usage of readily available construction material for conservation of these resources. road pavement construction with quality materials results in high cost of construction. thus, this research investigates engineering properties improvements of lateritic soil cement mix with intent to establishing its suitability in road pavement construction. 2. study area location and geology the study area (ibadan-iwo-osogbo highway and its environs) lies in the southwestern part of nigeria, lies between 7° 37.50’ n to 7° 48.18’ n latitudes and 4° 10’ e to 4° 30’ e longitudes. the road trends southwest to northeast direction and spreads approximately 86 km (figure 1). settlements around this major highway are linear, drained by many rivers and their tributaries with dendritic drainage pattern [5]. the aquiferous units of the area and typical basement geologic setting are weathered layer and the fractured bedrock. the area witnesses dry and rainy seasons of annual rainfall of 1,600 mm. the area undergoes undulating topography and is characterized by rain forest tropical zone with evergreen forest type of vegetation. the area of study falls in the precambrian geological complex terrain of nigeria with diverse rock types encompassing migmatite gneiss in the age of 2700 ma (archean) to 2000 ma (proterozoic) [6]. geologic rock units of this complex terrain is dominated in a triangular segment that forms the african crystalline basement rocks affected by geotectonic activities [7]. this extends to part of west african craton. the rock units of the area are within the migmatite-gneiss-quartzite complex, characterized majorly by ultramafic, felsic and charnockitic rocks [8]. these rock types have undergone series of deformation and metamorphism from 2000 ma (early proterozoic) to approximately 600 ma [9]. the highway cuts through major noticeable rock types in the area as shown in figure 2. migmatite gneisses in the area are mostly differentiated by medium grained well classified bands of diverse mineralogical composition [10]. in the area, weathering of gneiss, migmatite and granite resulted into formation of lateritic-soil with quartz, hornblende, biotite, microcline and plagioclase feldspars as the major mineralogical composition. the formation and composition of the lateritic soil varied over the parent rocks. the clay minerals constituents present in lateritic soils are kaolinite, montmorillonite and chlorite. other non-clay minerals present are quartz, feldspar, mica and goethite [11]. the presence of clay minerals derived from underlying rocks also necessitates the modification of the soil with cement for improved performance in road construction. 3. materials and study methods 3.1. soil-cement mix materials the soil-cement mix materials are cement, lateritic soil and water. they are the three basic materials needed to produce soil-cement mixture. asian review of environmental and earth sciences, 2022, 9(1): 23-33 25 © 2022 by the authors; licensee asian online journal publishing group figure 1. location map of area of study. figure 2. ibadan-iwo-oshogbo highway and environs geological map. 3.1.1. lateritic soils they are weathered, decomposed residual soils, which occur as surface deposits. they are distinguished by aluminum and iron oxides. lateritic soils may contain clay minerals; but they tend to leach out silica by water passing through the soil. lateritic soils have high clay content and lower cation exchange capacity. they have high clay content, thus, with water retention capacity. their formation from intense and prolonged weathering of the underlying parent rocks under strongly oxidizing and leaching conditions make them consist of less minerals and asian review of environmental and earth sciences, 2022, 9(1): 23-33 26 © 2022 by the authors; licensee asian online journal publishing group organic materials. formation of laterites under continuously wet regions characterized them with moist and irretrievable alteration when dried, while, those formed in regions of alternating wet and dry seasons have low plasticity, moisture content, cemented and compaction horizons. engineering properties of this soil are influenced by presence of sesquioxides (iron and aluminum oxides) thereby coating the soil particles. the research was carried out on ten bulky samples of lateritic soil collected from different parts of the area with each sample at depth range of 1.5 2 m. this is to ensure true representation of subsoil beneath this highway in a systematic order to reflect full coverage of the entire area. global positioning system (gps) was employed to record the coordinates and elevation of all sampling points. all samples obtained were cautiously labelled for laboratory analysis. the lateritic soil properties are presented in table 1. table 1. lateritic soil properties. soil properties outcome soil colour brown to reddish brown specific gravity 2.68 ± 0.04 clay content (%) 30.7 ± 7.7 moisture/water content (%) 6.6 ± 1.3 plasticity limit (%) 20.9 ± 2.3 liquid limit (%) 32.0 ± 6.0 soil plasticity index (%) 11.2 ± 4.3 american association of state highway and transportation officials (aashto) classification a-2-4 till a-7-6 unified soil classification system (uscs) cl–ml and cl or ol soil optimum moisture content 15.30 ± 3.10 (%) soil maximum dry density 1.87 ± 0.11 (mg/m3) soil california bearing ratio unsoaked soaked 40.8 ± 18.6 (%) 28.5 ± 12.8 (%) unconfined compressive strength (kn/m2) 145.7 ± 19.0 3.1.2. portland cement portland cement was employed in this work as binder in soil stabilization. this conformed to british standard code of practice bs 12 [12] standard as stabilizing agent. it was examined from different engineering tests for road pavement suitability. the soil response to varying cement content is the focus of this study. it attempts to establish the effects of cement content increase on the soil strength characteristics. 3.1.3. borehole water borehole water in line with british standard code of practice bs 3148 [13] standard was utilized in this study. 3.1.4. soil-cement mixtures soil cement is a combination of portland cement, powdered soil and water. soil-cement mixtures were formed by carefully mixing dry pulverized soil and cement to a required homogeneous paste with cement content in the range 2 – 10% of the dry soil. measured water from moisture-density analysis was added to the dry soil cement mix (paste) for compaction. 8% quantity of portland cement is required to adequately improve and harden the lateritic soils. 3.2. test methods the soil water content was determined at the laboratory and thereafter dried for further analysis. lumps in the soil were pulverized after two weeks of drying. this was intended to allow them retail their initial grain sizes. geotechnical tests were carried out on soil samples following british standard (bs) 1377 [14] test procedures. soaked soil samples in weak calgon solution helps separate the soil grains in the process of wet sieving. soil sedimentation test was performed using hydrometer method by stokes law. 3.2.1. atterberg limits test the soil samples were subjected to atterberg limit tests; plastic limit (pl), liquid limit (ll), and plasticity index (pi) in order of astm d4318 [15] standard technique. the casagrande method was employed in determining the values of liquid limit (soil change from liquid to plastic form) corresponding to water content arising from change in volume of soil behaving as in liquid form. likewise, plastic limit (pl) determination corresponds to water content at point of soil change from flexible plastic to semi-solid form. the soil at this point rolled in a form of threads of diameter of about 3 mm and crumbled. the plastic limit is also the crumbling point where the moisture content of crumbled soil placed in a moisture container was determined. water content range between liquid limit and plastic limit represents the plasticity index, which specifies the extent of soil plasticity. linear shrinkage (ls) is the reduction in soil sample length when dried from its original state. it aids in evaluating soil suitability as construction material in roads, building foundations and other civil engineering works. a pycnometer was used in determining the soil specific gravity values. linear shrinkage (ls) = (lo – l1)/lo × 100% (1) where lo = initial soil length, while l1 = final dry soil length. 3.2.2. compaction test this test determines the soil maximum dry density (mdd) and optimum moisture content (omc) according to astm d698 [16] testing procedure, using standard proctor energy level. these tests were performed on natural and stabilized soils at different percentages of cement mix content. in these tests, weight of the compaction mould and soil compacted were noted. from the test, moisture content was derived from top and bottom compacted soil asian review of environmental and earth sciences, 2022, 9(1): 23-33 27 © 2022 by the authors; licensee asian online journal publishing group samples. this was done repeatedly for the unstabilized soils and those stabilized with 2%, 4%, 6%, 8% and 10% cement upon which their mdd and omc were established. 3.2.3. unconfined compression test stabilized soil strength was achieved by performing unconfined compressive strength (ucs) test. thus, characteristics of structural load distortion can be measured in determining its strength. these natural and stabilized soils were compressed in moulds of 1000 cm3 at their omc values. unconfined compressive strength tests performed on the compacted soil samples from the moulds were cured for 7 and 14 days respectively according to astm d2166 [17] stipulations in a triaxial machine. at expiration of curing, the samples were de-waxed and centrally positioned at the compression testing machine lower plate and subjected to a compressive force at 1%/min strain control. the soil ucs was thereafter noted and recorded from the stress–strain curve at the point where failure occurred. load and deformation were then measured and this gives insight into the relationship between stress-strain. 3.2.4. cbr test cbr (california bearing ratio) a penetration test for assessing strength of road subgrade and pavements. it is carried out on soil samples (soaked and unsoaked) with their omc and mdd respectively as stipulated by astm d1883 [18] testing procedures. 4. results of study and discussion 4.1. index properties of soil grain size distribution analysis of the lateritic soils showed gravel content in the range 1.3 – 28.7 % table 1. sample 3b is characterized with highest gravel content and lowest fines. despite the pressure heave characterized by clay-rich soil [19] with clay amount of about 30.7 ± 7.7% table 1 70% of lateritic soils analyzed are within acceptable range of nigerian general specifications for highways [20] of not exceeding 35% clay content. the soils specific gravity is in the range 2.64 – 2.75 with an average of 2.68 ± 0.04 table 1. the values are within 2.60 and 2.80 standard range [21]. coarse soil is characterized by lower specific gravity, while fine grained soil is of higher values. the specific gravity of soils in this area exceeds the recommended [20] value of 2.2 for bridges and roads. atterberg limit values shown in table 1 is consistent with the classification of soil and determines the shrink/swell potential as well as clay mineralogy of a soil [22]. the liquid limit ranged from 24.0 – 40.8% with mean value of 32.0 ± 6.0%, the plastic limit ranged from 17.4 – 24.1% with mean value of 20.9 ± 2.3% and the plasticity index of the soils is in the range 7.0 – 17.5% with mean value of 11.2 ± 4.3% table 1. some of the samples (samples 1a, 1c, 8a and 8b) are not suitable for subbase while most of them are unsuitable for base course materials due to their high liquid limit values greater than 35% and 30% maximum recommended for subbase and base course materials respectively [20]. the lateritic soils range in the group a-2-4 to a-7-6 classification of american association of state highway and transportation officials (aashto) [23] classification system rated as excellent to good and fair to poor subgrade highway materials. this implies that the soils (a-2) have clayey or silty gravel and sand proportion rated quality road construction materials and clayey soils (a-7) rated as poor construction materials (table 2). plasticity index of some of the soils are above 12%, which means they are unsuitable for road construction [20] thus, the need for soil stabilization. based on the plasticity chart (plot of plasticity index versus liquid limit) as illustrated in figure 3, the soils are inorganic in nature with low medium plasticity. they fall in the category of cl and cl‒ml (inorganic clayey/silty soil of low to medium plasticity) in line with unified soil classification system. asian review of environmental and earth sciences, 2022, 9(1): 23-33 28 © 2022 by the authors; licensee asian online journal publishing group table 2. soils classification and its aggregate mix. general classification granular materials (35% or less passing no. 200) silt-clay materials (more than 35% passing no. 200) group classification a-1 a-3 a-2 a-4 a-5 a-6 a-7 a-1-a a-1-b a-2-4 a-2-5 a-2-6 a-2-7 a-7-5’ a-7-6 sieve analysis, % passing: no. 10 (2.00 mm) 50 max … … … … … … … … … … no. 40 (425 µm) 30 max 50 max 51 min … … … … … … … … no. 200 (75 µm) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min characteristics of fraction passing no. 40 (425 µm): liquid limit … … 40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min plasticity index 6 max n.p. 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11 mina usual types of significant constituent materials stone fragments, gravel and sand fine sand silty or clayey gravel and sand silty soils clayey soils general rating as subgrade excellent to good fair to poor note: a plasticity index of a-7-5 subgroup is equal to or less than ll minus 30. plasticity index of a-7-6 subgroup is greater than ll minus 30. asian review of environmental and earth sciences, 2022, 9(1): 23-33 29 © 2022 by the authors; licensee asian online journal publishing group figure 3. soil classification/plasticity chart. 4.2. compaction optimum moisture content (omc) and maximum dry density (mdd) of compacted soils with addition of the different content of cement are shown as curves in figure 4 and figure 5. the addition of 2% cement resulted in mdd increase for all soils tested except for sample 3b, while increase from 4% to 10% cement content led to reduction in mdd of the soils. this indicates mdd reduction with corresponding cement increase in the soil above 2%. reduction in mdd could be ascribed to soil coating by cement which act as soil void filler. dry density increase is an indication of soil improvement, but in this case, reduction in dry density indicates the need for low compactive energy to achieve maximum dry density. omc increases with increase in cement content from 8.99% to 16.07%, thus, reflects clay reduction, establishing coarser grains with bulky surface area. it can also be ascribed to more water in the flocculant soil matrix from the reaction of cement. figure 4. soil sample 1a compaction curve. figure 5. soil sample 3b compaction curve. 4.3. cbr result results of the unsoaked and soaked cbr values at 7 and 14 curing days for the lateritic soils stabilized with cement are illustrated in figure 6a, 6b, 7a and 7b. they displayed cbr increase with increase in cement content. chemical reaction between soil grains and cement results in an increase in cbr coupled with the soil compaction. generally, there is increase in cbr (soaked and unsoaked) values with cement content increase from 0% till 8% for sample of soils cured for 7 and 14 days. addition of cement content exceeding 8% resulted into cbr reduction, thus 8% cement soil mix is considered optimal for improved state of the soil. from the results, cement soil mix cured in 14 days have stronger effect on soil bearing capacity/strength for road pavement construction. addition of cement has improved soils to attain the requirements for subgrade and asian review of environmental and earth sciences, 2022, 9(1): 23-33 30 © 2022 by the authors; licensee asian online journal publishing group subbase in road construction [24]. this improvement reduces cost of road construction as thickness of pavement reduces. figure 6. cement content effect on unsoaked (a) and soaked (b) cbr cured soils in 7 days. figure 7. cement content effect on unsoaked (a) and soaked (b) cbr cured soils in 14 days. asian review of environmental and earth sciences, 2022, 9(1): 23-33 31 © 2022 by the authors; licensee asian online journal publishing group 4.4. unconfined compression test the effect of curing on ucs values are pronounced as shown in figure 8a and 8b. cementation of the grains of soil led to increase in ucs as cement content increases. also, increase in ucs values with cement content increase from 0% till 8% for sample of soils cured in 7 and 14 days. addition of cement content exceeding 8% resulted into ucs reduction, thus 8% cement soil mix is considered optimal for improved state of the soil. stronger effects are achieved with soil cement mix cured in 14 days than that of 7 days, which shows that soil strength is improved for better quality performance with respect to cement content and curing period. ucs values increase could be ascribed to cement solidification property that enables compaction of soil mass with resultant increased strength. the ucs values of soil cement cured in 14 and 7 days (845.5 – 1011.6 and 761.7 – 872.1 kn/m2) are within the 750 – 1500 kn/m2 stipulated nigerian general specifications for highways [20] at 8% cement content. the results show that the strength structural properties (cbr and ucs) of the soil is improved on addition of 8% cement content. it also confirms proper curing of soil cement mix in 14 days with increased strength and as effective stabilizer. figure 8. cement content effect on cured soils ucs in 7 days (a) and 14 days (b). modelling of structural strength properties of soil cement mix as revealed in figure 9 and 10 and illustrated with equations 2 – 7 with their corresponding r2 values revealing the correlation extent between the strength properties and cement contents. curing period was observed to have impact on the soil strength planned for road construction sustainability. strong relstionship exist between the strength indices of soil cement mix cured in 14 days with values of r2 ≥ 0.8. this reveals that prolong curing time is essential for compacted soil cement mix for enhanced geotechnical engineering properties and to improve the quality of lateric soil used as road construction materials. asian review of environmental and earth sciences, 2022, 9(1): 23-33 32 © 2022 by the authors; licensee asian online journal publishing group figure 9. cbr/ ucs 7 days vs cement content; (a) cbr 7 days vs cement content (b) ucs 7 days vs cement content. cbr 7 days vs cement content figure 9a cbr/ ucs 7 days vs cement content model 7 days-cbr unsoaked = 0.567 %cement2 – 11.55 %cement + 37.42 (2) r2 = 0.570 7 days-cbr soaked = 0.157 %cement2 – 3.272 %cement + 27.11 (3) r2 = 0.413 ucs 7 days vs cement content figure 9b 7 days-ucs = 4.823 %cement2 – 112.3 %cement + 107.5 (4) r2 = 0.90 where: 7 days-cbrunsoaked, 7 days-cbrsoaked and 7 days-ucs are: cbr and ucs of soil cement mix cured for 7 days. %cement is cement content. figure 10. cbr/ ucs 14 days vs cement content; (a) cbr 14 days vs cement content (b) ucs 14 days vs cement content. cbr 14 days vs cement content figure 10a cbr/ ucs 14 days vs cement content model cbr unsoaked 14 days = 0.98 %cement2 – 17.89 %cement + 37.2 (5) asian review of environmental and earth sciences, 2022, 9(1): 23-33 33 © 2022 by the authors; licensee asian online journal publishing group r2 = 0.776 cbr soaked 14 days = 0.39 %cement2 – 6.82 %cement + 27.08 (6) r2 = 0.753 ucs 14 days vs cement content figure 10b ucs 14 days = 7.53 %cement2 – 147.20 %cement + 124.0 (7) r2 = 0.93 where: 14 days-cbrunsoaked, 14 days-cbrsoaked and 14 days-ucs are: cbr and ucs of soil cement mix cured for 14 days. %cement is cement content. 5. conclusion index properties of the soils reveal its unsuitability as road construction materials, thus necessitated its enhancement for such purpose. reduction in dry density indicates the need for low compactive energy to achieve maximum dry density with reduced cost of construction. the strength properties of the compacted cured soil cement mix improve with cement content increase from 0% till 8%. addition of cement content exceeding 8% resulted into soil strength reduction, thus 8% cement soil mix is considered optimal for improved state of the soil. enhanced strength condition of the soils has guaranteed its usefulness in flexible road pavement construction. prolong curing period of 14 days is confirmed necessary for soil cement mix planning to be used in sustainable civil engineering works as maximum load bearing capacity of the soil depend not only on increase cement content but curing time. improved soil bearing capacity offer reduction in pavement thickness with reduced/low construction cost. cement exclusively stabilize the soil on its addition of 8% with improved strength properties. soil cement mix could serve as alternative road construction material and cost-effective substitution for building construction mining and river sands. soil cement mix would minimize continuous exploration of natural resources for construction, civil engineering work failures, cost of construction, human and environmental losses. curing period was observed to have impact on the soil strength planned for sustainable road construction, as strong relstionship exist between the strength indices of soil cement mix cured for 14 days with r2 ≥ 0.8. references [1] o. ademila, "geotechnical influence of underlying soils to pavement failure in southwestern part of nigeria," malaysian journal of sustainable environment, vol. 4, no. 1, pp. 19-36, 2018. https://doi.org/10.24191/myse.v4i1.5604 [2] j. d. nelson and d. j. miller, expansive soils: problems and practice in foundation and pavement engineering. new york: john wiley and sons, inc, 1992. [3] p. sherwood, soil stabilization with cement and lime. state of the art review. london: transport research laboratory, hmso, 1993. [4] o. ademila, "engineering geological evaluation of some rocks from akure, southwestern nigeria as aggregates for concrete and pavement construction," geology, geophysics and environment, vol. 45, no. 1, pp. 31-31, 2019. https://doi.org/10.7494/geol.2019.45.1.31 [5] o. ademila, a. i. olayinka, and m. a. oladunjoye, "land satellite imagery and integrated geophysical investigations of highway pavement instability in southwestern nigeria," geology, geophysics and environment, vol. 46, no. 2, pp. 135--157, 2020. https://doi.org/10.7494/geol.2020.46.2.135 [6] a. annor, "u-pb zircon age for kabba-okene granodiorite gneiss: implication for nigeria’s basement chronology," african geoscience review, vol. 2, no. 1, pp. 101-105, 1995. [7] m. woakes, m. rahaman, and a. ajibade, "some metallogenetic features of the nigerian basement," journal of african earth sciences (1983), vol. 6, no. 5, pp. 655-664, 1987. https://doi.org/10.1016/0899-5362(87)90004-2 [8] m. a. rahaman, "recent advances in the study of the basement complex of nigeria. in: the precambrian geology of nigeria," in proceedings of the first symposium on the precambrian geology of nigeria organized by the geological survey of nigeria, under the auspices of the federal ministry of mines and power, from 14th to 17th october 1981 at durbar hotel, kaduna, geological survey of nigeria, 1981, pp. 11-43. [9] a. o. oyinloye, "geology and geotectonic setting of the basement complex rocks in southwestern nigeria: implications on provenance and evolution," earth and environmental sciences, pp. 98 – 117, 2011. https://doi.org/10.5772/26990 [10] o. ademila, "geophysical and geostatistical reserve estimates of migmatite-gneiss deposits from parts of southwestern nigeria," global journal of geological sciences, vol. 20, no. 1, pp. 109-128, 2022. [11] o. ademila, "engineering geophysical investigation of some unstable sections of ibadan-iwo-osogbo highway, southwestern nigeria," unpublished phd thesis, university of ibadan, ibadan, nigeria, 2017. [12] british standard code of practice bs 12, portland cement (ordinary and rapid hardening). london: british standard institution, 1996. [13] british standard code of practice bs 3148, test for water for making concrete. london: british standard institution, 1980. [14] british standard (bs) 1377, methods of testing soils for civil engineering purposes. london: british standards institution, 1990. [15] astm d4318, standard test methods for liquid limit, plastic limit and plasticity index of soils. west conshohocken, pa: american society for testing and materials, astm international, 2017. [16] astm d698, standard test method for laboratory compaction characteristics of soil using standard effort (12400 ft-ibf/ft3 (600 kn-m/m3)). west conshohocken, pa: american society for testing and materials, astm international, 2012. [17] astm d2166, standard test method for unconfined compressive strength of cohesive soil. west conshohocken, pa: american society for testing and materials, astm international, 2016. [18] astm d1883, standard test method for california bearing ratio (cbr) of laboratory compacted soils. west conshohocken, pa: american society for testing and materials, astm international, 2016. [19] o. ademila, "combined geophysical and geotechnical investigation of pavement failure for sustainable construction of owo-ikare highway, southwestern nigeria," nriag journal of astronomy and geophysics, vol. 10, no. 1, pp. 183-201, 2021. https://doi.org/10.1080/20909977.2021.1900527 [20] federal ministry of works and housing (fmwh), "general specification for roads and bridges," vol. 2, pp. 137-275, 2000. [21] p. h. wright, highway engineering, 6th ed. new york, usa: john wiley and sons, 1986. [22] m. carter and s. p. bentley, correlations of soil properties. london: pentech press publishers, 1991. [23] american association of state highway and transportation officials (aashto), standard specifications for transportation materials and methods of sampling and testing, 27th ed. washington dc, usa: american association of state highway and transportation officials, 2007. [24] o. ademila, "geotechnical properties and effects of palm kernel shell ash and cement on residual soils in pavement construction along owo-ikare road, southwestern nigeria," the pacific journal of science and technology, vol. 20, no. 1, pp. 365-381, 2019. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://doi.org/10.24191/myse.v4i1.5604 https://doi.org/10.7494/geol.2019.45.1.31 https://doi.org/10.7494/geol.2020.46.2.135 https://doi.org/10.1016/0899-5362(87)90004-2 https://doi.org/10.5772/26990 https://doi.org/10.1080/20909977.2021.1900527 14 © 2023 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 10, no. 1, 14-27, 2023 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v10i1.4439 © 2023 by the authors; licensee asian online journal publishing group flood zoning and developing strategies to increase resilience against floods with a crisis management approach faraz estelaji1 amirhossein afshari aghajari2 rahim zahedi3 ( corresponding author) 1department of construction engineering and management, faculty of civil engineering, khajeh nasir toosi university, tehran, iran. email: f.estelaji.27@gmail.com 2college of civil engineering, university of tehran, tehran, iran. email: a.afshari.agh@ut.ac.ir 3department of renewable energy and environmental engineering, university of tehran, tehran, iran. email: rahimzahedi@ut.ac.ir abstract assessment and planning of crisis management with the approach to natural flood disasters include many factors. in this regard, one of the basic principles of crisis management is based on the resilience of urban infrastructure against floods. this study developed strategies to increase resilience by flood zoning and crisis management. the investigation of the current situation shows that despite the efforts being made, the climatic and environmental conditions of the rivers, the settlements of the infiltration basin, the constructions, and the location inaccuracy of the following structures indicate many challenges in managing the current situation in various components of crisis management. in this regard, the main direction of this article is to evaluate the urban resilience of the khuzestan region against floods based on a crisis management approach and technique for order preference by similarity to ideal solution (topsis) and fuzzy weighting methods using geographic information system (gis). keywords: crisis management, flood disasters, flood zoning, gis, urban resilience, topsis. citation | estelaji, f., aghajari, a. a., & zahedi, r. (2023). flood zoning and developing strategies to increase resilience against floods with a crisis management approach. asian review of environmental and earth sciences, 10(1), 14–27. 10.20448/arees.v10i1.4439 history: received: 10 november 2022 revised: 27 december 2022 accepted: 6 january 2023 published: 30 january 2023 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this study received no specific financial support. authors’ contributions: all authors contributed equally to the conception and design of the study. competing interests: the authors declare that they have no conflict of interest. transparency: the authors confirm that the manuscript is an honest, accurate, and transparent account of the study; that no vital features of the study have been omitted; and that any discrepancies from the study as planned have been explained. ethical: this study followed all ethical practices during writing. contents 1. introduction ...................................................................................................................................................................................... 15 2. literature review ............................................................................................................................................................................ 16 3. methodology ..................................................................................................................................................................................... 17 4. results and discussion ................................................................................................................................................................... 23 5. conclusion ......................................................................................................................................................................................... 26 references .............................................................................................................................................................................................. 26 mailto:f.estelaji.27@gmail.com mailto:a.afshari.agh@ut.ac.ir mailto:rahimzahedi@ut.ac.ir https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v10i1.4439 https://orcid.org/0000-0001-6837-8729 asian review of environmental and earth sciences, 2023, 10(1): 14-27 15 © 2023 by the authors; licensee asian online journal publishing group contribution of this paper to the literature in this research, considering the slope of the land, land use, density of faults and fractures, geology, the density of waterways, amount of precipitation, and intensity of rainfall, the zoning of khuzestan region against floods using topsis and fuzzy weighting methods was done using gis. 1. introduction after flood occurrence, the performance of communication networks decreases significantly due to the possible closure of communication routes [1]. this contrasts with the fact that after natural disasters and emergencies, communication networks and access to relief centers play a vital role in saving human lives [2]. for this reason, the optimal distribution of utilities and relief centers is a problem that urban planners often deal with; because of the rapid population growth, there have been problems such as lack and lack of proper distribution of the necessary space for relief centers [3]. today, a geographic information system serves as a tool to create a unified and efficient database [4]. one of the fundamental goals of policymakers in the health sector of any country is to facilitate people's access to healthcare services so that all sections of society can benefit from these services [5]. therefore, the level of performance and coverage of relief centers is crucial to reducing human casualties during floods [6]. crisis management should not be considered only as a tactical response when a disaster occurs but as preventive activities within processes related to crisis prevention [7]. therefore, the location of public facilities is an example of the policies of plan-oriented governments, understanding the benefits of saving resources, increasing the efficiency and synergy of services, especially during a flood crisis, and increasing the sense of collectivism. such benefits are especially critical for governments experiencing rapid population growth [8]. 1.1. flood a flood is any flow, regardless of its generation source, that causes a significant increase in the amount of water at a certain point and has a limited duration. in this case, the water overflows from its natural bed and covers the surrounding lands, which may lead to financial and human losses [9]. according to the definition of the unesco hydrological culture, a flood is a short-term increase in the river’s water level to a peak from which the water level recedes with a slower rhythm [10]. in another definition, a flood may occur due to heavy, continuous rainfall, sudden snow melting in a watershed, or a dam breakage. however, the occurrence of flood causes destruction and damage to human centers and structures along the flood path [11]. in general, from a physical point of view, any surface flow, regardless of its creation factor, exceeding the natural or artificial bank of the river and covering the lowlands and river banks, is defined as a river flood [12]. as long as this phenomenon does not threaten life and assets of humans, it is not considered a dangerous event. a flood is a combination of short flows in a particular place with a steep slope, usually created in impermeable and low-resistant rocks and structures, that consists of three main parts: catchment basin, waterway, and alluvial cone. all the rains in the catchment basin meet in the form of small waterways to provide a significant flow rate in a large, elongated, narrow, and relatively long waterway. the basis for the formation of irregular discharges caused by sudden and heavy rains is mainly in the form of showers that occur in feeble and intermittent currents. floods are characterized by solid detection currents generated after each rain shower on bare and unstable lands and in waterways already cut by water flow and often on steep mountain slopes. in terms of intensity, they are often highly destructive. therefore, most of the villages and cities located at the foot of the mountains are constantly exposed to the danger of this phenomenon. considering the different views of the concept of a flood, it seems necessary to provide a comprehensive and complete definition of a flood. in general, it can be concluded that any surface flow is called a flood if: 1. according to custom and general opinion, it should be accompanied by an increase in the volume of water at a certain point. 2. to have a limited duration. 3. it usually overflows from the natural bed and covers the marginal lands. 4. bring financial and life losses. 1.2. urban resilience resilience means the ability to deal with difficult situations and respond flexibly to incidents that occur in the city. historically, the term "resilience" was first used in the early 17th century, meaning leap and return to one's self. after holling, the term resilience evolved in material science, ecology, and environmental studies and became a concept for the use of professionals, planners, and academics. based on that, resilience was described as returning to a stable state after any disruption in the system's performance or as the ability to absorb force or change with minor disruption to the efficiency of that system [13]. resilience has become critical as one of the main goals of empowerment in post-crisis rehabilitation and reconstruction. resilience in the context of social systems and when faced with an accident is defined as the ability of a social unit to absorb the risk of accidents, reduce the physical effects, postpone the time of social disruption when it occurs, and reduce the impact of future crises. 1.3. crisis disaster studies emphasize the impact of natural hazards on the artificial environment. this form of natural disaster consequence occurs when human activities and natural phenomena collide and turn disasters into crises [14]. therefore, the crisis can be considered the result of the interference of a series of factors of natural hazards among human communities [15]. recently, the role of planning in reducing accidents has been recognized. for example, risk reduction or integrated programs are one potential strategy to encourage safer development and gain public support [16]. it is necessary to make plans before the incidents. these plans will be effective when accompanied by the powerful presence of the community [17]. quality programs of local interest groups greatly impact environmental asian review of environmental and earth sciences, 2023, 10(1): 14-27 16 © 2023 by the authors; licensee asian online journal publishing group problems, especially natural hazards, and can increase the commitment level of elected officials [18]. based on these findings, selective areas to solve environmental problems should be created to use the existing communities in the planning process and facilitate reconstruction operations. politically oriented and influential social networks can improve civil servants’ commitment and society’s capacity. crisis in human societies happen periodically; therefore, people and societies have adopted different approaches in facing crises. the crisis cycle from the point of view of militia [19] is a four-stage cycle with the following stages in time. • preparedness: the ability of society to react and deal with disasters. • reconstruction: the set of measures taken after a disaster to save lives and minimize future losses. • short-term rehabilitation: short-term restoration and repair of vital arteries and infrastructure and livelihoods. • long-term rehabilitation: long-term restoration of the community to return to the past normal state [20] 2. literature review in 2018 wang, et al. [21] used a hybrid multi-criteria decision-making method for flood susceptibility mapping based on gis comparative assessment. this study proposed an approach to recognize flood-prone areas of the topla river. machine learning, statistical index, bivariate regression, multi-criteria decision-making approach, and gis were used as the main approaches for the abovementioned purpose. in another study carried out by ogato, et al. [22] a gis-based multi-criteria analysis of flooding risk and hazard in ambo town and its watershed was done. the investigation used the flooding hazard layer and two factors: land use and human population. the weighted linear combination method was used in the criteria map aggregation process for both flooding risk and flooding hazard. results demonstrated that more proportion of the watershed and the town are high and very high flooding hazard areas. flooding risk analysis revealed that more of the watershed, like half of the city, is a high and very high flooding risk area. in another study by ajjur and mogheir [23] using multi-criteria decision analysis and gis, urban flood hazard zoning was carried out in argentina. the methodology concentrated on analyzing the variables that control the water routing when high peak flows pass the drainage-system capacity [24]. the model consisted of four parameters: topography, groundwater table depths, distance to drainage channels, and urban land use. a final hazard map for each category was obtained using an algorithm derived from factors in a weighted linear combination. da silva, et al. [25] proposed a gisbased multidimensional decision model for improving flood risk prioritization in urban areas. the modeling is a multi-attribute utility theory (maut). to validate the model, a case study in a brazilian municipality is simulated with real data. visualizations of risk mapping developed from gis were used to discuss the results. being flexible and replicable in any region of the world brings advantages to this method. in 2022 a combination of machine learning, remote sensing, and gis was used by ullah, et al. [26]. to investigate the effects of changing climates and land uses on flood probability [27]. for this purpose, land use changes were predicted for the next 20 years by monitoring the past 20 years’ land use changes. this was done using the land change modeler (lcm) method. future climate change was evaluated as well using lars-wg software. the results manifested that elevation, land use, slope, distance from the river, and rainfall are the critical elements affecting flooding in this basin. jahangir, et al. [28] provided a spatial prediction of flood zonation mapping using an artificial neural network algorithm in the kan river basin. using this, discharge values and spatial modeling of floods in the kan river basin were predicted. seven inputs were considered in the optimized ai network, including slope curvature, slope, ndvi, geological units, flow accumulation, soil type, and rainfall. the output of the neural network was discharge values in stations. results demonstrated that utilizing gis spatial analysis with ai algorithms is one of the most efficient methods for forecasting the potential of natural disasters. batarseh, et al. [29] assessed groundwater quality for irrigation in arid regions using gis-zoning maps and irrigation water quality index (iwqi). due to ussl and wilcox diagrams which were in line with iwqi results, the groundwater was primarily classified as unsuitable for irrigation purposes without prior treatment. cai, et al. [30] utilized a hydrodynamic model and fuzzy comprehensive evaluation with the gis technique for flood risk assessment. the mfce model consists of three input indicators: the exposure factor, the hazard factor, and the vulnerability factor. the results indicated that compared with the risk assessment of the mfce model, the risk distribution map of the hazard factor changed significantly when the studied area was under a storm. chau, et al. [31] used gis to map the impacts on agriculture from severe floods in vietnam. eighty-six flood depth marks were interpolated using the inverse distance weighting algorithm to generate the water surface, and a dem was employed to form the flood inundation map. the generated maps indicated that the 1:10, 1:20, and 1:100-year floods led to the land being inundated by 27%, 31%, and 33%, respectively. in 2019 land-use zoning for protecting the built heritage in the bagan archeological zone in myanmar was evaluated by edwards, et al. [32]. publicly available satellite information was analyzed as one of the vital factors of the local conservation regime. doing so, it was concluded that a restrictive zoning regime has controlled urban sprawl and helped conserve the monuments. lai, et al. [33] used a rule mining for flood risk zoning based on an ant colony. the results showed that ant-miner expresses higher accuracy and more simple rules that can be utilized to generate flood risk zoning maps faster and easier than the decision tree method. compared to the fuzzy comprehensive evaluation and random forest, antminer has significant superiorities both in computing time-saving and implementation step-reducing. qi and altinakar [34] provided a gis-based decision support system for integrated flood management under uncertainty using two-dimensional numerical simulations. this system can use classified remote sensing and interact with image layers and gis feature layers like survey database, zoning layer, and census block boundaries. test results indicated that this new system introduces a very reliable and versatile environment for predicting various flood damage. sadeghi-pouya, et al. [35] proposed an indexing approach to assess flood vulnerability in the western coastal cities of mazandaran. results demonstrated that the indexing method results in a relative sense and an overall picture of the exposure of urban toward floods, the urban zones surrounded by two rivers are in danger of a high level of vulnerability. zhang and song [36] introduced a case study in which the optimization of wetland restoration siting and zoning in flood retention areas of river basins was done. a site-specific methodology asian review of environmental and earth sciences, 2023, 10(1): 14-27 17 © 2023 by the authors; licensee asian online journal publishing group was developed to identify potential functional zones and sites for wetland restoration, optimizing the available zones and spatial distribution to maximize flood control and human and regional development. 3. methodology 3.1. khuzestan’s flood zoning generally zoning in the current study consists of two main stages: 1. gathering the needed information and obtaining data layers: in this stage, essential information layers such as khuzestan's geological map, dem, hydrometric information, region's streams, and precipitation regime data regarding flood potential in the area were gathered by gathering the previous data from various data sources. at this stage, the information was evaluated using gis, and a decision tree diagram as criteria and sub-criteria was compiled. adequate privacy for each potential flooding criterion was determined and standardized using fuzzy membership functions and the topsis process. afterward, using topsis and fuzzy procedures, which are multicriteria decision-making methods, the criteria's degree of importance was calculated. finally, by compiling all the information using the index overlap method, flood zoning was prepared. figure 1 shows the flowchart of the research figure 1. research’s flowchart. 2. obtaining the effective factors: at this stage, information layers and various data sources were evaluated, and due to the factors practical to the flood occurrence and khuzestan’s geological specifications, upcoming elements were introduced as the effective ones: • ground inclination: including the region’s topographic slope information layers. • land use: consists of natural or unnatural land usage. • density of faults and fractures: consists of all the regional faults. • geology: this layer contains the lithology of the formations in the region. • density of the stream: has the main and sub-streams of the khuzestan city. • precipitation amount: contains the average annual rain in different regional zones. • precipitation intensity: includes the moderate maximum daily rain. asian review of environmental and earth sciences, 2023, 10(1): 14-27 18 © 2023 by the authors; licensee asian online journal publishing group 3.2. data processing after influential factors determination in the flood occurrence, related information layers should be prepared. the following section will discuss how the data was organized and entered into the function. 3.2.1. processing the steep layer the basins' slope is one of the main factors that control the river's surface flow time and water concentration. it affects the amount of infiltration, surface flow, soil moisture, and groundwater in the basin. basins with a steep slope usually have a compensation profile. as a result of the steep slope, the speed of the water flow increases, which in turn decreases the infiltration and evaporation amount. after a short period, the rain turns into a stream, and a flood occurs. such basins have a shorter hydrograph range and higher peaks. for this reason, if the permeability is low in mountainous areas, flood damages and inundation will sour. in this research, after preparing dem using the slope software, khuzestan city's slope map was obtained. the slope layer stands among the linear quantitative layers, standardized using fuzzy functions. according to the characteristics of the studied area and experts' opinion, the minimum slope that causes run-off and flood is -1% (equal to 5 degrees), and the maximum slope up to which the amount of flooding increases linearly is 100% (equivalent to 45degrees). slopes over 45 degrees are completely flooded regardless of the experimental flooding factors. the slope map, dem and standardized slope are shown in figure 2. figure 2. a) slope map, b) dem, c) standardized slope. 3.2.2. land usage layer this layer demonstrates land use (like agricultural lands, jungles, and residential). the land-usage map figure 3 illustrates essential information about the type of surface cover of the land, changes and developments made by humans, and the density of the vegetation. this information changes regarding the type of land use, surface permeability, and flood potential. the land use map prepared by the natural resources and environmental protection organization of khuzestan has been used to create this layer. the land use layer is one of the land cover types that shows the surface characteristics of the basin, such as the vegetation of agricultural lands in urban areas, etc. the changes and transformations of the surface cover of the land can create a neutralizing or destructive effect when floods occur. with increasing vegetation, the runoff rate and flood risk decrease and increase as the urban a b c asian review of environmental and earth sciences, 2023, 10(1): 14-27 19 © 2023 by the authors; licensee asian online journal publishing group levels increase. for this purpose, the prepared land use layer has been standardized by assigning importance values between zero and one according to expert opinion and field vision. the critical values of different uses and the standardized map of the land use layer can be seen in table 1. table 1. values of importance of different uses in khuzestan province. weight application 0 salty and salty lands (canopy less than 5%) 0 marsh (wet areas) 0.35 thickets and shrubs (canopy cover more than 10%) 0.33 sand dunes (less than 5% canopy cover) 0.1 dense forest (canopy cover more than 50%) 0.2 thin forest (canopy cover 5-25%) 0.15 semi-dense forest (canopy cover 25-50%) 0.3 dense pastures (over 50% canopy cover) 0.5 semi-dense pastures (canopy cover 25-50%) 0.6 low-density pastures (canopy cover 5-25%) 0.33 sandy areas (less than 5% canopy cover) 0.9 uncovered lands and rocky outcrops 0.7 river bed 0.2 hand-planted forests 0.15 aquaculture and gardens 0.3 dry farming 0 water levels 1 residential areas 0.15 reeds figure 3. a) land use map, b) standardized land use map. 3.2.3. rain intensity layer processing among the precipitation characteristics, precipitation intensity stands among the most critical factors that cause runoff and flooding. if the rainfall's intensity exceeds the infiltration capacity of the watershed, it causes the runoff to flow and causes floods. the more the intensity of rainfall increases, the more the runoff volume is created throughout the basin, and more severe floods occur. this layer is obtained using the average maximum intensity of daily rainfall. the average of the 25 years was prepared in the synoptic stations of khuzestan province. the rainfall intensity layer is of importance in the flood potential. as the intensity increases, the volume of runoff and flooding will rise. therefore, a linear and increasing relationship between the intensity of precipitation in the field and the flood potential is observed. considering that any point with higher rainfall intensity will have more intense floods, the maximum phase membership for this layer is equivalent to the highest daily rainfall intensity (99.1 mm/day), and the minimum phase membership is equal to the lowest daily rainfall intensity (31 mm/day). standardized rainfall map is shown in figure 4. average annual rainfall intensity map and its standardized. a b asian review of environmental and earth sciences, 2023, 10(1): 14-27 20 © 2023 by the authors; licensee asian online journal publishing group figure 4. a) average annual rainfall intensity map, b) standardized annual rainfall intensity map. 3.2.4. precipitation layer processing besides the precipitation intensity, the amount of precipitation is also considered one of the critical meteorological characteristics of the flood potential in an area. flooding and the amount of precipitation have a direct relationship. generally, more flooding will occur as the rainfall in one region is more remarkable than in others. the average annual rainfall of meteorological devices of khuzestan province was used to investigate the effect of precipitation amount on flood zoning. the equation of the precipitation height of khuzestan province was obtained using the average annual precipitation of the stations regarding the direct relationship between the land surface's height and the amount of precipitation and insufficient regional stations. afterward, using the obtained equation and the digital elevation model (dem), the average annual rainfall map of the province was prepared. as mentioned, precipitation is the most critical cause of flooding and is directly related to the increase in altitude and the risk of flooding. in other words, precipitation is the raw material for floods. therefore, according to the expert opinion and characteristics of the studied area, the linear and ascending membership function was used to standardize this layer. since there are floods in the areas with the lowest rainfall, this layer's minimum (zero) value was considered lower than the minimum rainfall amount of (175 mm). the minimum value of (zero) for this layer, equivalent to the lowest average precipitation among the stations of the abadan station, was set to (150 mm) in the function. the maximum value was considered equal to the maximum amount of precipitation in this layer of (14.3 mm) figure 5 shows a) the average annual rainfall map and b) the standard deviation of annual rainfall map. figure 5. a) average annual rainfall map, b) standard deviation of annual rainfall map. a b a b asian review of environmental and earth sciences, 2023, 10(1): 14-27 21 © 2023 by the authors; licensee asian online journal publishing group 3.2.5. waterway compaction layer processing the network of waterways in the basin shows how the runoff is discharged from the basin's surface. the lower the permeability of the basin surface, the more developed the network of waterways in the basin will be. simply put, the waterways network results from the volume of runoff and floods in an area. therefore, the more developed the basin channels are, the more flood-prone that bay is. first, the province's waterways shape file, prepared by the khuzestan water and electricity organization, was combined with the canals obtained from the dem layers in the arcgis environment to prepare this layer. then the output layer in google earth software was verified with actual waterways, adding new channels and excluding the others. after measuring the length of the finalized lines, the density layer of waterways was calculated using the density function in the arcgis environment. this parameter is directly related to flooding. the higher the density of waterways, the higher the runoff performance and faster drainage in the basin. therefore, the incremental linear relationship has been used to determine the membership of this layer. according to the study area's waterways network, the minimum density of waterways with the potential of creating a flood should be considered zero. this indicates that the area with high permeability or sedimentation basins that could not form a waterway network practically is not flood-prone. waterway density map is shown in figure 6. figure 6. a) waterway density map, b) standardized waterway density map. 3.2.6. geological layer processing one of the influential factors in creating floods is the resistance of the formations that make up the basin's surface against erosion and water permeability, each formation showing a different resistance. the resistance of the formations depends on the constituent minerals composition type, sintering way, porosity of the layering, the outcrop and erosion between the layers, etc. the geological map of khuzestan province was used to prepare this layer figure 7 and divide the different lithologies of the basin in terms of flood potential. an essential phenomenon in creating runoff and flooding is permeability. any factor that reduces this phenomenon will increase runoff and flood. the permeability is more affected by lithological characteristics such as porosity, grain size, layering, and degree of crystallization. tectonics and structural geology are other factors that cause changes in the permeability of rock units to the extent that it sometimes plays an influential role concerning lithology. the tectonic factor, applying stress to different rock units, causes faults and fractures. these fractures create secondary porosity in the rock, which causes permeability and eventually reduces flooding. the higher the density of these fractures, the higher the permeability. it is practically impossible to determine the location and measure the fractures, considering the studied area's size. but since the existence of a fracture depends on its fault, on a large scale, it is possible to achieve the highest density of fractures logically by locating the faults and calculating their density. merging the faults illustrated by satellite images and those drawn in the geological maps of the province, this layer was prepared. afterward, the distribution map of the faults of the province was obtained. fault density is a critical geological factor that plays a vital role in surface water infiltration alterations. the higher the density of faults and fractures, the greater the permeability and the lower the flood risk. therefore, there is a linear and decreasing relationship between these two phenomena. considering the characteristics of the area and the fact that runoff is formed in areas with a high density of faults and fractures (permeability is not 100%), the minimum value of this layer was considered to be a little higher than the maximum density of faults. its maximum value was equivalent to the lowest fault density (lowest permeability), zero. in this way, as the density increases from zero, the risk of flooding decreases. the lithology layer is one of the most important for knowing the permeability strength and runoff creation potential from the geological perspective. the lithology layer is prepared using the characteristics of the area's geological formations. it has been standardized by assigning importance values a b asian review of environmental and earth sciences, 2023, 10(1): 14-27 22 © 2023 by the authors; licensee asian online journal publishing group between zero and one for each lithology in terms of flood risk. the assigned values are based on field observations and expert judgment. matters of lithology importance of various formations are shown in table 2. figure 7. a) geological layers processing, b) active faults of the region. a asian review of environmental and earth sciences, 2023, 10(1): 14-27 23 © 2023 by the authors; licensee asian online journal publishing group table 2. importance values of geological formations in flood potential. weight formation weight formation 0.5 tale zang 0.2 quaternary 0.47 asmari shahbazan 0.05 quaternary (sandy sediments) 0.83 kashkan 0.92 lahbary 0.53 shahbazan 0.75 nishan 0.42 darian 0.89 aghajari 0.85 geru 0.8 bakhtiari 0.8 emam hassan 0.45 gachsaran 0.89 amiran 0.95 gurpi 0.35 bangestan 0.87 pabde 0.44 darian fahlian 0.4 asmari 0.45 asmari jahrom 0.3 ilam seruk 0.6 sorme 0.75 kajdomi 0.15 conglomerate 0.9 pabde gurpi 0.85 razak 0.32 landslide 4. results and discussion 4.1. weighting the criteria the weight of each factor indicates its importance and value compared to other elements in flood potential zoning operations. therefore, the conscious and correct selection of weights is a great help in proper zoning. after applying the membership functions to the layers, considering their distinct effect on the flood potential, weighting to layers becomes crucial. this operation is done using expert knowledge. 4.2. critic weighting in this method, expert opinion is not very involved. in the critic method, for each evaluation criterion, there is a range of changes in measured values among pixels (options), which is expressed as a membership function. the changes in the measured values of each criterion are reflected on a vector. the vector carries the measured criteria changes in each pixel (options), expressed in the standardized model. each vector for the criteria used has statistical parameters, including standard deviation. these parameters represent the degree of difference in the corresponding criterion values. after calculating the standard deviation of the investigated factors and parameters, a different matrix of m * m dimensions is created, which includes the correlation coefficients between the formed vectors. the coefficients are determined by summation of the divided columns, which were the product of contrast and the standard deviation. in connection with the critic weighting method, it can be said that the most critical capability of this method is that the expert is not involved in the calculations, and the data is analyzed based on the amount of interference and conflict and correlation between the criteria. this process of data processing causes the role of each factor to be correctly applied in the final calculation result. in table 3, the final weight of the criterion proposed in flood risk zoning is stated. table 3. the level of conflict, standard deviation and final weight of the criteria proposed in flood risk zoning. final weight standard deviation set of contradictions criterion name information layer hazard’s name 0.209 94.421 0.898 slope cover and surface topography flood 0.095 104.214 4.698 land use 0.238 171.681 6.889 precipitation intensity hydroclimate 0.135 268.171 4.641 precipitation 0.118 43.559 0.684 waterway density 0.103 101.703 4.668 lithology geology 0.098 92.329 0.719 fault density 4.3. overlap as effective criteria and sub-criteria have different weights and all of them should participate in overlapping, the index overlapping method has been used for this task. in this method, the standardized layer obtained from each criterion (𝑋𝑖) is multiplied by the weight of that criterion (w𝐽). this is done for all criteria and sub-criteria, and new layers are created which are overlapped using different functions such as product, sum or, and and gama. σw𝑗 = 1 𝐴𝑖=σw𝑗𝑋𝑖𝑗 following the field and statistical evidence for the zoning of potential floods, and at this stage, the output of the topsis method is considered as the final output. among the factors influencing flood occurrence, slope factors, precipitation intensity, and physiographic characteristics stand among the most important ones in causing floods. according to the final output of topsis, these points are flood-prone and high-risk areas. such places are mainly in the northern to eastern regions and parts of the southeast of khuzestan province, which corresponds to the steepest and rainiest places. figure 8 shows the flood zoning of khuzestan province. khuzestan province is divided into four areas with high flood potential, which is shown in red, medium flood potential in green, low flood potential in yellow, and places without possibility in blue. as shown, the northern and northeastern regions have the highest flood potential, and as we move through the northeast to the south and southeast of this province, the flood potential decreases. in this research, after identifying the flood-prone areas with high potential, using a strengths, weaknesses, opportunities and threats analysis (swot) matrix with the analytic hierarchy process (ahp) weighting method in expert choice software, strategies were presented to increase the resilience of the residential regions against floods. table 4 and table 5 show the swot analysis. asian review of environmental and earth sciences, 2023, 10(1): 14-27 24 © 2023 by the authors; licensee asian online journal publishing group figure 8. flood zoning in khuzestan province. table 4. evaluation matrix of internal strengths and weaknesses. final score (score*coefficient) coefficient (ahp) score internal weaknesses (w) row 0.2 0.1 2 construction in the area of dez, karun, karkheh rivers 1 0.085 0.085 1 roads inadequate slope to dispose surface water 2 0.03 0.015 2 insufficient number of surface water disposal channels 3 0.15 0.075 2 passage of critical infrastructures in the borders 4 0.025 0.025 1 heterogeneous land use 5 0.2 0.1 2 high potential of flooding in the plains and northern areas of khuzestan province 6 0.035 0.035 1 high potential of flooding in the eastern basins of the province 7 0.065 0.065 1 high potential of flooding in the southeastern basins of the province 8 0.11 0.055 2 danger existence in the field of dez 9 0.09 0.045 2 danger existence in the field of karun 10 0.025 0.025 1 danger existence in the field of karkhe 11 0.07 0.035 2 lack of management coordination between organizations 12 0.08 0.04 2 lack of preparation for rescue in accidents 13 0.134 0.067 2 no rivers’ dredging 14 0.066 0.033 2 settlements construction in the dams’ area 15 final score (score*coefficient) coefficient (ahp) score internal powers (s) row 0.165 0.055 3 waterways’ density 16 0.18 0.045 4 faults’ density 17 0.144 0.036 4 low flood potential in central basins 18 0.256 0.064 4 vegetation in the area 19 2.11 1 40 sum it can be seen that the total score of internal factors is equal to 2.11, which is less than 2.5, which indicates that there is an internal weakness based on our existing plan. asian review of environmental and earth sciences, 2023, 10(1): 14-27 25 © 2023 by the authors; licensee asian online journal publishing group table 5. evaluation matrix of points of external threats and opportunities. final score (score*coefficient) coefficient (ahp ) score external threats (t) row 0.134 0.134 1 heavy rainfall with long return periods 1 0.2 0.1 2 high gradient upstream 2 0.132 0.066 2 low flood potential in central basins 3 0.12 0.06 2 lack of dams in the upstream of the province (lorestan province) 4 0 0.041 1 high flood potential in upstream areas 5 0.041 0.058 2 the period of abundant returns of rainfall in the upper reaches of the province 6 0.116 0.17 1 the impact of global warming and climate change in the last 2 years 7 0.17 0.121 2 soil erosion in the upstream 8 0.242 0.05 2 no dredging of rivers in the upstream 9 final score (score*coefficient) coefficient (ahp) score external opportunities (o) row 0.316 0.079 4 construction of dams 10 0.484 0.121 4 presence of specialist for flood planning 11 2.05 1 23 sum in the matrix of external factors, it can be seen that the sum of external points is equal to 2.055, less than 2.5, which indicates unfavorable conditions of this sector. this means that external threats are mostly threatening the plan. results show a 0.055 difference in the obtained value meaning that the internal factors are in a better condition than the external factors. table 6 shows the summation of internal and external factors table 6. summation of internal and external factors. external factors internal factors threat (t) opportunity (o) weakness (w) strength (s) 1.155 0.8 1.365 0.745 coefficient summation of composite factors wo st wt so 2.165 1.9 2.52 1.545 4.4. implementation suggestions and solutions as it can be seen, the largest number obtained is related to the wt factors of the project’s weaknesses and threats. considering that, defensive strategies should be adopted and the project's position is in a risky state. therefore, we suggest the following strategies: 1. using prefabricated dams for use in critical times and increasing resilience. 2. continuous dredging of rivers (once a year). 3. conducting studies to reduce losses through crisis management. 4. preparing to bear losses (increasing resilience). 5. strengthening the position of risk management instead of crisis management in future floods. 6. certificating geotechnical and engineering characteristics of important structures (dams, bridges, main roads, industrial towns, power plants, etc.) 7. identifying and revising technical sanctuaries of rivers based on sedimentological and morphological components as a support for hydrometric device data. 8. comprehensive studies of the erodibility of rock units by basin and climate. 9. obligation to carry out watershed plans. suggestions for increasing flood resilience include flood mitigation through watershed-level construction methods such as: a. use of water containment method with water b. use of dry dams c. use of wipp walls d. use of diversion dam e. use of dams f. pi ting g. use of reservoir dams h. farrowing i. banquet j. use of protective walls k. use of diversion channels 2) flood reduction through construction methods specific to urban and rural areas such as: a. use of water gate device b. use of quick dam c. use flood block d. heritage flood guard 3) flood reduction through low-impact development methods to dispose of runoff: a. vegetative swale b. porous asphalt c. permeable pavement (porous pavement) d. filter strip asian review of environmental and earth sciences, 2023, 10(1): 14-27 26 © 2023 by the authors; licensee asian online journal publishing group 4) management strategies for mitigating the effects of floods: a. careful and sufficient attention in complying with the rules and standards of urban development b. observing the privacy of waterways and rivers and flood plain zoning c. continuous control of the floodplain d. non-interference in canals and manipulation of water passages e. creating permeable surfaces in the city and not converting open lands into urban structures f. converting low lands and pits of big cities into parks and green spaces g. modifying the course and section of the river h. reducing the slope of the river i. grading of canals and rivers j. flood spreading k. watershed management 5) people's participation strategy in flood crisis management cycle: a. public information and education b. specialized training c. building trust between people and officials in flood management d. handing over some local land management affairs to the people 5. conclusion khuzestan region has a special place due to its prominent features of flooding. the investigation of the current situation shows that despite the efforts being made, the climatic and environmental conditions of the rivers, the settlements of the infiltration basin, the existing spaces, and the constructions carried out in the sanctuaries of the rivers as well as the incorrect location of the infrastructures, has created challenges in the management of the current situation in the various components of construction management. therefore, this research was conducted according to the existing challenges and the country's planning approach regarding the flood issue. in this article, considering the slope of the land, land use, density of faults and fractures, geology, the density of waterways, amount of precipitation, and intensity of rainfall, the zoning of khuzestan region against floods using topsis and fuzzy weighting methods was done using gis. the research results showed that the northern, northeastern, and southeastern parts have high potential compared to other areas in terms of floods. then, using the swot model, strategies and practical suggestions were introduced to increase the resilience of this region against floods. the model of this research and the results of this research, while being used in the studied area, are also applicable in other areas. references [1] k. banipal, "strategic approach to disaster management: lessons learned from hurricane katrina," disaster prevention and management: an international journal, vol. 15, no. 3, pp. 484-494, 2006. https://doi.org/10.1108/09653560610669945 [2] s. h. alsamhi et al., "uav computing-assisted search and rescue mission framework for disaster and harsh environment mitigation," drones, vol. 6, no. 7, p. 154, 2022. https://doi.org/10.3390/drones6070154 [3] k. gwilliam, "urban transport in developing countries," transport reviews, vol. 23, no. 2, pp. 197-216, 2003. https://doi.org/10.1080/01441640309893 [4] g. f. bonham-carter and g. bonham-carter, geographic information systems for geoscientists: modelling with gis (no. 13). burlington ma: elsevier, 1994. [5] h. mirzavand, a. aslani, and r. zahedi, "environmental impact and damage assessment of the natural gas pipeline: case study of iran," process safety and environmental protection, vol. 164, pp. 794-806, 2022. https://doi.org/10.1016/j.psep.2022.06.042 [6] n. cotes and v. cantillo, "including deprivation costs in facility location models for humanitarian relief logistics," socio-economic planning sciences, vol. 65, pp. 89-100, 2019. https://doi.org/10.1016/j.seps.2018.03.002 [7] w. t. coombs, "parameters for crisis communication," the handbook of crisis communication, pp. 17-53, 2010. https://doi.org/10.1002/9781444314885.ch1 [8] p. pegkas, "the effect of government debt and other determinants on economic growth: the greek experience," economies, vol. 6, no. 1, pp. 1-19, 2018. https://doi.org/10.3390/economies6010010 [9] m. a. mohit and g. m. sellu, "mitigation ofclimate change effects through non-structural flood disaster management in pekan town, malaysia," procedia social and behavioral sciences, vol. 85, pp. 564-573, 2013. https://doi.org/10.1016/j.sbspro.2013.08.385 [10] r. zahedi, r. eskandarpanah, m. akbari, n. rezaei, p. mazloumin, and o. n. farahani, "development of a new simulation model for the reservoir hydropower generation," water resources management, vol. 36, no. 7, pp. 2241-2256, 2022. https://doi.org/10.1007/s11269-022-03138-9 [11] z. şen, flood modeling prediction and mitigation. beykoz, istanbul turkey: springer, 2018. [12] m. s. mousavi, a. ahmadi, and a. entezari, "forecast of using renewable energies in the water and wastewater industry of iran," new energy exploitation and application, vol. 1, no. 2, 2022. https://doi.org/10.54963/neea.v1i2.47 [13] r. francis and b. bekera, "a metric and frameworks for resilience analysis of engineered and infrastructure systems," reliability engineering & system safety, vol. 121, pp. 90-103, 2014. https://doi.org/10.1016/j.ress.2013.07.004 [14] e. a. keller and d. e. devecchio, natural hazards: earth's processes as hazards disasters and catastrophes, 4th ed. new york: routledge, 2014. [15] h. ma, y.-h. chiu, x. tian, j. zhang, and q. guo, "safety or travel: which is more important? the impact of disaster events on tourism," sustainability, vol. 12, no. 7, pp. 1-12, 2020. https://doi.org/10.3390/su12073038 [16] a. k. jha, r. bloch, and j. lamond, cities and flooding: a guide to integrated urban flood risk management for the 21st century. bangkok thailand: world bank publications, 2012. [17] r. zahedi and s. golivari, "investigating threats to power plants using a carver matrix and providing solutions: a case study of iran," international journal of sustainable energy and environmental research, vol. 11, no. 1, pp. 23-36, 2022. https://doi.org/10.18488/13.v11i1.2965 [18] s. d. brody, "are we learning to make better plans? a longitudinal analysis of plan quality associated with natural hazards," journal of planning education and research, vol. 23, no. 2, pp. 191-201, 2003. https://doi.org/10.1177/0739456x03258635 [19] d. j. francis, civil militia: africa's intractable security menace? new york: taylor & francis, 2017. [20] s. manzano et al., "using the past to manage the future: the role of palaeoecological and long‐term data in ecological restoration," restoration ecology, vol. 28, no. 6, pp. 1335-1342, 2020. https://doi.org/10.1111/rec.13285 [21] y. wang et al., "a hybrid gis multi-criteria decision-making method for flood susceptibility mapping at shangyou, china," remote sensing, vol. 11, no. 1, pp. 1-31, 2018. https://doi.org/10.3390/rs11010062 https://doi.org/10.1108/09653560610669945 https://doi.org/10.3390/drones6070154 https://doi.org/10.1080/01441640309893 https://doi.org/10.1016/j.psep.2022.06.042 https://doi.org/10.1016/j.seps.2018.03.002 https://doi.org/10.1002/9781444314885.ch1 https://doi.org/10.3390/economies6010010 https://doi.org/10.1016/j.sbspro.2013.08.385 https://doi.org/10.1007/s11269-022-03138-9 https://doi.org/10.54963/neea.v1i2.47 https://doi.org/10.1016/j.ress.2013.07.004 https://doi.org/10.3390/su12073038 https://doi.org/10.18488/13.v11i1.2965 https://doi.org/10.1177/0739456x03258635 https://doi.org/10.1111/rec.13285 https://doi.org/10.3390/rs11010062 asian review of environmental and earth sciences, 2023, 10(1): 14-27 27 © 2023 by the authors; licensee asian online journal publishing group [22] g. s. ogato, a. bantider, k. abebe, and d. geneletti, "geographic information system (gis)-based multicriteria analysis of flooding hazard and risk in ambo town and its watershed, west shoa zone, oromia regional state, ethiopia," journal of hydrology: regional studies, vol. 27, p. 100659, 2020. https://doi.org/10.1016/j.ejrh.2019.100659 [23] s. b. ajjur and y. k. mogheir, "flood hazard mapping using a multi-criteria decision analysis and gis case study gaza governorate, palestine," arabian journal of geosciences, vol. 13, no. 2, p. 44, 2020. https://doi.org/10.1007/s12517-019-5024-6 [24] s. daneshgar and r. zahedi, "investigating the hydropower plants production and profitability using system dynamics approach," journal of energy storage, vol. 46, p. 103919, 2022. https://doi.org/10.1016/j.est.2021.103919 [25] l. b. l. da silva, j. s. humberto, m. h. alencar, r. j. p. ferreira, and a. t. de almeida, "gis-based multidimensional decision model for enhancing flood risk prioritization in urban areas," international journal of disaster risk reduction, vol. 48, p. 101582, 2020. https://doi.org/10.1016/j.ijdrr.2020.101582 [26] i. ullah et al., "an integrated approach of machine learning remote sensing, and gis data for the landslide susceptibility mapping," land, vol. 11, no. 8, pp. 1-23, 2022. https://doi.org/10.3390/land11081265 [27] r. zahedi, a. ahmadi, and s. gitifar, "reduction of the environmental impacts of the hydropower plant by microalgae cultivation and biodiesel production," journal of environmental management, vol. 304, p. 114247, 2022. https://doi.org/10.1016/j.jenvman.2021.114247 [28] m. h. jahangir, s. m. mousavi reineh, and m. abolghasemi, "spatial predication of flood zonation mapping in kan river basin, iran, using artificial neural network algorithm," weather and climate extremes, vol. 25, p. 100215, 2019. https://doi.org/10.1016/j.wace.2019.100215 [29] m. batarseh et al., "assessment of groundwater quality for irrigation in the arid regions using irrigation water quality index and gis-zoning maps: case study from abu dhabi emirate, uae," groundwater for sustainable development, vol. 14, p. 100611, 2021. https://doi.org/10.1016/j.gsd.2021.100611 [30] t. cai, x. li, x. ding, j. wang, and j. zhan, "flood risk assessment based on hydrodynamic model and fuzzy comprehensive evaluation with gis technique," international journal of disaster risk reduction, vol. 35, p. 101077, 2019. https://doi.org/10.1016/j.ijdrr.2019.101077 [31] v. n. chau, j. holland, s. cassells, and m. tuohy, "using gis to map impacts upon agriculture from extreme floods in vietnam," applied geography, vol. 41, pp. 65-74, 2013. https://doi.org/10.1016/j.apgeog.2013.03.014 [32] b. edwards, t. frasch, and j. jeyacheya, "evaluating the effectiveness of land-use zoning for the protection of built heritage in the bagan archaeological zone, myanmar—a satellite remote-sensing approach," land use policy, vol. 88, p. 104174, 2019. https://doi.org/10.1016/j.landusepol.2019.104174 [33] c. lai et al., "flood risk zoning using a rule mining based on ant colony algorithm," journal of hydrology, vol. 542, pp. 268-280, 2016. https://doi.org/10.1016/j.jhydrol.2016.09.003 [34] h. qi and m. s. altinakar, "a gis-based decision support system for integrated flood management under uncertainty with two dimensional numerical simulations," environmental modelling & software, vol. 26, no. 6, pp. 817-821, 2011. https://doi.org/10.1016/j.envsoft.2010.11.006 [35] a. sadeghi-pouya, j. nouri, n. mansouri, and a. kia-lashaki, "an indexing approach to assess flood vulnerability in the western coastal cities of mazandaran, iran," international journal of disaster risk reduction, vol. 22, pp. 304-316, 2017. https://doi.org/10.1016/j.ijdrr.2017.02.013 [36] x. zhang and y. song, "optimization of wetland restoration siting and zoning in flood retention areas of river basins in china: a case study in mengwa, huaihe river basin," journal of hydrology, vol. 519, pp. 80-93, 2014. https://doi.org/10.1016/j.jhydrol.2014.06.043 asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. https://doi.org/10.1016/j.ejrh.2019.100659 https://doi.org/10.1007/s12517-019-5024-6 https://doi.org/10.1016/j.est.2021.103919 https://doi.org/10.1016/j.ijdrr.2020.101582 https://doi.org/10.3390/land11081265 https://doi.org/10.1016/j.jenvman.2021.114247 https://doi.org/10.1016/j.wace.2019.100215 https://doi.org/10.1016/j.gsd.2021.100611 https://doi.org/10.1016/j.ijdrr.2019.101077 https://doi.org/10.1016/j.apgeog.2013.03.014 https://doi.org/10.1016/j.landusepol.2019.104174 https://doi.org/10.1016/j.jhydrol.2016.09.003 https://doi.org/10.1016/j.envsoft.2010.11.006 https://doi.org/10.1016/j.ijdrr.2017.02.013 https://doi.org/10.1016/j.jhydrol.2014.06.043 1 © 2024 by the authors; licensee asian online journal publishing group asian review of environmental and earth sciences vol. 11, no. 1, 1-9, 2024 issn(e) 2313-8173 / issn(p) 2518-0134 doi: 10.20448/arees.v11i1.5695 © 2023 by the authors; licensee asian online journal publishing group hydrodynamic regimes and proposed structure for flood drainage and navigation stability in thuan an estuary, vietnam nguyen thanh hung1 vu dinh cuong2 nguyen tien thanh3 nguyen van hung4 trieu quang quan5 ( corresponding author) 1,2,4,5key laboratory of river and coastal engineering, vietnam academic for water resources, 1-3 nr, 165 alley, chua boc street, dong da, hanoi, vietnam. 1email: nthung@vawr.org.vn 2email: cuongvd.vkhtlvn@gmail.com 4email: hungnv.ktb@gmail.com 5email: trieuquan.180896@gmail.com 3thuyloi university, 175 tay son, dong da, hanoi, vietnam. 3email: thanhnt@tlu.edu.vn abstract thua thien hue province is significantly affected by conditions of climate change and sea level rise. located in central vietnam, the province experiences various climate-related challenges that have a strong impact on its environment and communities. furthermore, the complexity of hydrodynamic regimes at main estuaries is reasonably challenge for the development of socioeconomic, especially in water transportation. as a large estuary of thua thien hue province, thuan an play a special role in flood drainage and waterway navigation of huong river. therefore, understanding the hydrodynamic regime of thuan an estuary is crucial due to the continuous alterations in its morphology during monsoon seasons. sedimentation within the estuary creates obstacles for the river mouth entering channel, while erosion affects the northern and southern coasts. these changes have direct implications for flood drainage and waterway navigation. to gain insights into the hydrodynamic regime, this study focuses on further interpretation the hydrodynamic regimes in thuan an inlet using delft3d model combined with arcgis tools. by combining scientific modeling and practical implications, this study contributes to a better understanding the hydrodynamics of thuan an estuary, ultimately facilitating sustainable development and management of this vital waterway system. importantly, proposed structure for flood drainage and navigation stability in thuan an estuary is considered with the elongation of 2 jetties. the proposed measure shows that the flood drainage is insignificantly affected and the water level at mostly locations in the river is not changed. keywords: central vietnam, delft3d, hydrodynamic regime, thua thien hue, thuan an estuary, training works, tropical cyclones, water transportation. citation | hung, n. t., cuong, v. d., thanh, n. t., hung, n. v., & quan, t. q. (2024). hydrodynamic regimes and proposed structure for flood drainage and navigation stability in thuan an estuary, vietnam. asian review of environmental and earth sciences, 11(1), 1–9. 10.20448/arees.v11i1.5695 history: received: 27 march 2024 revised: 26 april 2024 accepted: 10 may 2024 published: 4 june 2024 licensed: this work is licensed under a creative commons attribution 4.0 license publisher: asian online journal publishing group funding: this research is supported by the ministry of agriculture and rural development, vietnam. institutional review board statement: not applicable. transparency: the authors state that the manuscript is honest, truthful, and transparent, that no key aspects of the investigation have been omitted, and that any differences from the study as planned have been clarified. this study followed all writing ethics. competing interests: the authors declare that they have no competing interests. authors’ contributions: all authors contributed equally to the conception and design of the study. all authors have read and agreed to the published version of the manuscript. contents 1. introduction ......................................................................................................................................................................................... 2 2. materials and methods ...................................................................................................................................................................... 2 3. results and discussions ..................................................................................................................................................................... 5 4. conclusions .......................................................................................................................................................................................... 9 references ................................................................................................................................................................................................. 9 mailto:nthung@vawr.org.vn mailto:cuongvd.vkhtlvn@gmail.com mailto:hungnv.ktb@gmail.com mailto:trieuquan.180896@gmail.com mailto:thanhnt@tlu.edu.vn https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://www.doi.org/10.20448/arees.v11i1.5695 https://orcid.org/0009-0003-6986-8916 https://orcid.org/0009-0009-7231-2998 https://orcid.org/0000-0002-1995-2568 https://orcid.org/0009-0001-6369-0454 https://orcid.org/0009-0001-8482-3930 asian review of environmental and earth sciences, 2024, 11(1): 1-9 2 © 2024 by the authors; licensee asian online journal publishing group contribution of this paper to the literature this study provides the measure of elongated 2 jetties for flood drainage and navigation stability in thuan an estuary, vietnam based on deeply understanding the hydrodynamic characteristics. the proposed measure illustrates the flood drainage is insignificantly affected and the water level at mostly locations in the river is not changed. 1. introduction the development of spits leading to the closure of the inlet or river has significant consequences for water exchange and both commercial and recreational navigation. the accumulation of sediment in the estuary not only hampers waterway transportation but also contributes to obstructive flooding, resulting in downstream river basin inundation [1]. thuan an estuary has been strongly deposited by sandspits developed from the north and south of the estuary banks. even though 2 jetties at the north and south banks of the estuary are built up since 2015, the sediment process at the channel of the estuary has been still happening. the deposition of sediment directly affects flood drainage and waterway navigation as well as causing disturbance in socio-economic development [2]. huong river in thua thien hue province flows into the east sea through tam giang lagoon before to thuan an estuary located ini thua thien hue province. thuan an estuary serves as the connection between the huong river and the sea. it is a wave-dominated estuary situated in a microtidal, wave-dominated coastal environment. the coastal area is significantly influenced by the seasonal monsoon regime with large northeast waves from october to march and calm southeast waves from april to september each year. as a result, the morphology of the entrance to thuan an estuary undergoes dynamic seasonal changes due to the distinct variations in the direction of wave-induced longshore sediment transport between the two monsoon seasons [2]. the sediment process at the estuary is influenced by various factors, including wave characteristics, river flow, and sediment supply from nearby beaches. to understand and identify the factors that control the development of spits and estuary sedimentation, a combination of observations and mathematical modeling is employed. in order to overcome the limitations of field measurement data, remote-sensing technologies utilizing freely available satellite images are utilized. these long-term and widespread satellite images cover a vast majority of locations on earth. to simulate the sedimentation and morphological changes at thuan an estuary, the delft3d numerical model is employed. this model allows for the accurate representation of sedimentation processes and the dynamic evolution of the estuary's morphology. by utilizing this numerical model, researchers can gain valuable insights into the sedimentation patterns and the resulting changes in the estuary's shape over time. this information is crucial for understanding the impact of sedimentation on flood management, waterway navigation, and the overall stability of the estuarine ecosystem. sedimentation at the estuary is dependent on several factors, such as the wave characteristics, river flow, and sediment supply from the adjacent beaches. factors controlling the development of spits and estuary sedimentation can be identified through observations and mathematical modelling. the remote-sensing technologies with free satellite images, available in the long-term, and cover most places on earth is used in favor of the limited field measurement data. the delft3d numerical model is used to simulate the sedimentation and morphological change at the thuan an estuary. the proposed measure to address the sedimentation issue in thuan an estuary involves the elongation of the existing jetties at the north and south banks. it is essential that these measures are designed and implemented in harmony with the surrounding natural environment rather than conflicting with it. to achieve this, a deep understanding of sediment transport processes in morphological systems is crucial [3] the primary objective of this study is to have a comprehensive understanding of the current hydrodynamic regime in the estuary. the hydrodynamic model delft3d has been utilized, utilizing observation data as input. through simulations, the model assesses the hydrodynamic conditions under the existing situation and different scenarios considering the proposed structure solutions. it is noted that the impacts of the proposed structure in stabilizing the coastal area surrounding the estuary are considered. the aim is to mitigate sedimentation in the navigation channel and enhance the flood drainage capacity through thuan an estuary. by studying the effects of the proposed structure, effective solutions can be developed to maintain the stability of the estuary's geomorphology. by analyzing the outcomes of these simulations, researchers can evaluate the effectiveness of the proposed structure in stabilizing the estuary and reducing sedimentation. this analysis provides valuable insights into the feasibility and potential impacts of the proposed measures, enabling the development of informed and effective strategies for managing sedimentation and enhancing the overall functionality of thuan an estuary. 2. materials and methods 2.1. materials the temporal remote sensing satellite data including landsat tm (thematic mapper) and landsat oli (operational land imager) are used for assessing shoreline changes. the landsat imagery is freely downloaded from the us geological survey web site (http://glovis.usgs.gov/). furthermore, the images of landsat in thua thien hue province (path 125/row 49) taken from 1999 to 2023 are downloaded with a spatial resolution of 30m. for this study, the bathymetry data at a scale of 1: 5,000 for thuan an estuary is surveyed by the vietnam academy for water resources in 2023, combined with the topographic maps of 1:50,000 to 1:10.000 scale for coastal areas published by ministry of natural resources and environment of viet nam. figure 1 presents the study area with the positions of currents and wave characteristics. asian review of environmental and earth sciences, 2024, 11(1): 1-9 3 © 2024 by the authors; licensee asian online journal publishing group figure 1. thuan an estuary in vietnam map and positions of discharge measurement (q); water level, wave, currents (nl). 2.2. methods 2.2.1. coastline analysis arcgis software (esri) is used for coastline extraction from remote sensing data. the shoreline is precisely identified through the process of handling remote sensing images. the boundary between land and sea in the classified image is converted into a vector file and needed a manual edit whereby the inland features not related to the shoreline are removed [4]. 2.2.2. delft3d fm model the numerical model delft3d based on the depth-averaged model is used to simulate the hydrodynamic and morphological changes of thuan an estuary [5]. grid of the model is orthogonal curved with cell size varying from higher resolution in the river mouth and coastal areas and to lower resolution in offshore to increase the model accuracy and reduce computation time consuming. importantly, the grid extended from 4.5 km upstream of thuan an estuary to the location of thao long bridge on the huong river and through thuan a river mouth about 30km into the east sea to a depth of 40m. the grid is set to ensure that nodes along the open boundary are placed at the national oceanic and atmospheric administration (noaa) wave data position. domain of the model consists of 150,132 grid cells. model boundaries are designed as (i) thuan an estuary uses discharge boundary (q ~ t) from the calculation results of the huong river network model mike11 for river boundaries (ii) for offshore boundaries, the offshore limit is defined by the position of the wavewatch iii (ww3) data used as offshore forcing boundary conditions for the model including both of water level and wave boundaries [6]. also, the open boundary water level used the tides available by ocean topography experiment (topex) global model (http://g.hyyb.org/archive/tide/tpxo/tpxo_web/global.html). tpxo7.2 is one of the most recent versions of global tide with high resolution of 0.25 degree which provide tidal water level for eight constituents (m2, s2, n2, k2, k1, o1, p1, and q1) [7]. the hourly water levels interpolated to several points along the offshore open boundary. the hourly wave variables are retrieved from the ww3 global model (https://polar.ncep.noaa.gov/waves) with resolution 0.50 degree; including significant wave height, wave direction, and peak wave period. reanalysis wind data including, u-velocity, v-velocity components, and pressure parameters obtained from noaa (https://polar.ncep.noaa.gov), are used in this study. the sediment transport and morphodynamic computations are carried out by means of the delft3d-sed module. the updated expression of the transpor2004 formula [8, 9] is used to calculate the bed load and suspended sediment transport. the bed shear stress calculation is based on the van rijn [8] roughness predictor. the sediment is sandy with a measured median grain size about 0.2 mm a sediment density equal to 2.650 kg.m−3. the dry bed density is set as equal to 1.600 kg.m−3. the suspended sediment at the beginning of the computation had a representative diameter equal to the d50 value. a minimum water depth equal to 0.2 m is assumed for the sediment transport calculation. the model is set to allow 12 to 24h for hydrodynamic spin up before they executed the bedlevel changes. http://g.hyyb.org/archive/tide/tpxo/tpxo_web/global.html asian review of environmental and earth sciences, 2024, 11(1): 1-9 4 © 2024 by the authors; licensee asian online journal publishing group 2.2.3 existed jetties structures and elongation proposal for thuan an estuary the wave and longshore current cause sediment transport along the thuan a coast, and it moves sediment into the estuary causing estuary sedimentation, which hamper flood drainage and waterways navigation. engineering structures are required to stabilize the shoreline and inlets, to reduce sedimentation and to increase the channel depth to allow marine navigation and flood drainage through thuan an estuary. thuan an estuary has a very important role for navigation and flood drainage so the engineering construction must meet both above requirements. the engineering construction must be based on the following criteria: 1) engineering construction must ensure the river mouth have full capacity to discharge the designed flood (without reducing the flood discharge or significantly increasing the water level of the designed flood). 2) the engineering construction must meet the requirements of waterway navigation. to achieve these goals, 2 jetties at south and north estuary banks are constructed in 2010 with 705m and 642m long (red colour structures in figure 2). due to existing of sediment, the prolongation of the jetties (yellow jetties part in figure 2) is proposed to prevent sand moving into estuary channel from both north and south sides of the estuary. these jetties have a task to concentrate river flow for stabilizing the navigation channel, thus it required that the jetty spacing should not be too narrow, allowing full flood drainage capacity during the flood season. the length of the jetties should extend beyond the littoral transport zone. figure 2. jetties construction system to stabilize thuan an estuary for flood drainage and navigation. the prolongation of two jetties is proposed to reach bathymetry elevation of -4.5m, which is natural seabed elevation that maintaining for waterway transport. the elongation of the south and north jetties are 160 m and 440 m long respectively. the distance between the heads of the 2 jetties is 900 m. the estuary channel is dredged to the level of -4.5 for waterway navigation 2.2.4 different scenario design and simulation the hydrodynamics regime at thuan an estuary area varies seasonally. flow and wave regimes for northeast and southwest seasons strongly affect the estuary and coastal areas vicinity. currents induced by seasonal waves caused sediment transport along the coast to deposit at estuary channels which creates obstacles for navigation and flood drainage through the estuary channel. thus, calculation scenarios could be selected for seasonal waves and designed flood to facilitate the proposed measure of the estuary stabilized construction. hydrodynamics boundary condition in whole year 2017 is selected for accessing the hydrodynamics regimes of thuan an. in this year, there are 16 storms and depressions happening in central coast of vietnam. there are also 2 floods events from river occurred in huong river and its branches in this year. to calculate structures, hydrodynamics boundary condition of flood event with 2% frequency is selected for accessing the flood obstruction effect of proposing structure to flood drainage capacity (2% flood frequency is regulated by vietnamese law to this river system). boundaries data of scenarios are presented in table 1. the purpose of each scenario is given as follows: scenario sc1, sc2 is used to assess the hydrodynamics regimes (flow, wave) and morphological change around the estuary in the northeast monsoon and southwest monsoon seasons in june 2017 and november 2017, respectively. these hydrodynamics regimes interact with scenarios of the estuary existing condition and proposed structures. it is noteworthy that in this study, the labels of pa0 and pact stand for estuary existing condition and proposed structures, respectively. the scenarios sc3 has been used to assess the obstruction impact of the proposed structure to the estuary flood drainage. asian review of environmental and earth sciences, 2024, 11(1): 1-9 5 © 2024 by the authors; licensee asian online journal publishing group table 1. summary of model simulations. scenarios name hydrodynamics proposed structure system purposes sc0 hydrodynamics boundary condition in whole year 2017 existing estuary condition (pa0) access the hydrodynamics regimes of thuan an sc1 hydrodynamics boundary condition in june 2017 proposed structure system (pact) + dredging channel access the hydrodynamics and morphological change around the estuary in the northeast monsoon with proposed structure system sc2 hydrodynamics boundary condition in november 2017 proposed structure system (pact) + dredging channel access the hydrodynamics and morphological change around the estuary in the southwest monsoon with proposed structure system. sc3 hydrodynamics boundary condition of 2% flood event proposed structure system (pact) + dredging channel access the flood obstruction effect of proposing structure to flood drainage capacity to access the ability of reducing wave, preventing sediment moving into estuary channel, flood drainage capacity, the values of wave height, current velocity and water level are extracted at 6 locations (p1, p2, p3, p4, p5, p6) in figure 2 for comparing between model scenarios. 3. results and discussions 3.1. calibration for the purpose of model calibration, the study used water level, current, and wave data measured from april 10, 2023 april 15, 2023. figure 3. calibration of hydrodynamic model for water level (a), current magnitude (b), current direction (c), water height (d) and wave direction (e). the calculation results of water level (h), current velocity (v), current direction, significant wave height (w) and wave direction are compared with that of observed data. figure 3 (a, b, c, d, e) shows the small magnitude of discrepancies. model performance is evaluated using error statistics such as root mean squared error (rmse), it is frequently used to measure of the size of the discrepancies between the values predicted by a model and the observed data. the rmse index for comparisons of water level, current and waves between calculated and actual measured results are 0.07, 0.1, 0.11, respectively. thus, the results of water level, currents and waves calculation are basically consistent with the observed data at the thuan an estuary despite some discrepancies. based on the findings, it can be stated that the numerical model effectively captures and describes the behavior of currents, waves, and water levels with a reasonable level of accuracy. 3.2 coastline changes in the thuan an estuary the evaluation of shoreline changes in the thuan an estuary area from 1999 to 2023 is divided into two distinct periods. the first period spans from 1999 to 2015, during which thuan an estuary did not have any jetty structures. the second period covers the years 2015 to 2023, during which jetty structures are implemented in the thuan an estuary. the position of the shoreline from landsat images taken in 1999, 2020 and 2023 show that the shoreline changes in the thuan an estuary during the entire period 1999-2023 is generally described as there is a regularly asian review of environmental and earth sciences, 2024, 11(1): 1-9 6 © 2024 by the authors; licensee asian online journal publishing group erosion and retreatment towards the mainland, the sandspits extended into the entrance of thuan an estuary channel for the northern coastline during 1999. due to the development of sandspits on both banks, the average width of the river mouth is only about 350m. especially, the southern coastline extends further into the sea when compared to the northern coastline. additionally, there is a tendency for erosion along the coast, resulting in a gradual movement of the sandspit towards the entrance of the estuary. after 2 jetties are built at both estuary banks in 2015, the coastlines in vicinity of estuary became stable. in the year 2020, the northern coastline is accreted toward the sea about 150 200 m; the southern coastline is most accreted towards the sea about 150 m at the location close to the southern jetty (figure 2). it is noted that the insufficient length of the jetties has led to the ongoing movement of the southern sandspit towards the entrance of the estuary. comparison coastal line position of the year 2023 with coastal line of the year 2020, the northern coastline at 2023 is maintained stable and accreted with a maximum of about 50 80 m wide. the southern coastline is accreted the most about 50 m at the location close to the southern jetty (figure 2). the river mouth width is expanded and maintains an average width of about 450 500 m. figure 4 depicts the shoreline changes in thuan an during 1999-2023. it can be observed from this figure that there has been a significant change in the width of the sandspits at both the northern and southern banks of thuan an estuary after building the jetty structures in 2015. the coastline in the thuan an estuary has been developed by accretion towards the sea, except for the section at the end of the northern sandspit where the coastline has been retreated. the northern coastline of thuan an estuary is frequently eroded in the past (strong erosion occurred on the coastline in thai duong village), but after having a breakwater and jetty structures, it has been accreted and stabilized. the width of the river mouth has been remaining relatively stable. however, the southern coastline continued to be accreted at a strong rate with large volumes of sand transporting from the south by the longshore current into the river mouth. figure 4. shoreline change in thuan an estuary area in the years 1999-2020-2023. 3.3. sedimentation mechanism of thuan an estuary to understand the sedimentation mechanism at thuan an estuary, analysis of hydrodynamics regime at thuan an estuary is carried out. hydrodynamic modeling results of the year 2017 are used (scenario sc0 in table 1). wave heights and current flows are extracted at three points at the estuary: p1 in the northern site, p2 in middle, p3 in the southern site (figure 5). the magnitude of tide in the study area is about 0.5-0.6m. the wave fields in the thuan an estuary area are shown in figure 5. the northeast wave direction is the dominant wave direction in this area with wave heights ranging from 0.3m to 2.5m in the coastal area. wave height during the southwest monsoon period from april to september mainly ranges from 0.3m to 1.2m with an east-northeast wave direction. during the northeast monsoon period from january to march and from october to december, the wave height is much higher than the wave height during the southwest monsoon period, ranging from 0.5m to 2.5m with the northeast wave direction. thus, the coastal wave height in the thuan an estuary area has a large difference between the two seasons in a year with higher wave happened in northeast monsoon than in southwest monsoon season. asian review of environmental and earth sciences, 2024, 11(1): 1-9 7 © 2024 by the authors; licensee asian online journal publishing group figure 5. (a) wave rose and (b) current rose near shore at thuan an estuary in 2017. at points p1 and p3 are the north and the south bank area of thuan an estuary; the flow velocity at the south bank tends to be higher than the flow at the north bank. during the southwest monsoon from april to september, the flow speed can reach 0.2m/s. during the northeast monsoon, the flow velocity is higher than during the southwest monsoon, ranging from 0.1m/s to 0.43m/s. thus, the flow velocity in the northeast monsoon is greater than the southwest monsoon. at point p2 (river mouth area), the flow velocity is in the north south direction with flow speeds ranging from 0.1m/s to 0.55m/s. from the results of hydrodynamic analysis, it shows that during the northeast monsoon period, with large wave heights ranging from 0.5m 2.5m, large coastal currents move from south to north carrying a large amount of sand and mud causing sedimentation in the thuan an estuary area. there is also the influence of the flow from the huong river; in flood season, flood flow carries out mud and sand from upstream to the river mouth. because of large waves, tidal currents and river mouth width sudden expansion the sand and mud deposited. thus, the sedimentation at thuan an estuary is caused by two main factors: wave and current flow during the northeast monsoon period combined with flood flow carrying sediment and sand from the river. 3.4 seasonal wave and current regime as showed in figure 6, wave regime during the southwest monsoon period including wave heights in existing estuary condition (pa0) and proposed structure (pact) are from 0.1m 0.16m. the southern jetty shields the waves propagate into estuary thus, wave height in proposed structure is lower than wave height in existing condition about 20%-30% when going into the estuary (point p1, p2 and p4). during the northeast monsoon, the northeast wave propagates directly into the river mouth, so the wave height between the pa0 and the pact are approximately the same, with an average wave height from 0.16m to 0.29m. thuan an estuary has very small tidal fluctuations (tide amplitude is about 0.4-0.6 m, this is area where tide amplitude is smallest along coast of vietnam), so the current velocity at the estuary is significantly small, that ranging from 0.1m/s to 0.3m/s. current velocity at points p1, p2, p3, p4 in the estuary channel are increased due to the effect of narrowing channel width, caused by jetties existence. current speed at point 2 increases 2 times in pact compared to the current speed. the decrease trend of current speed happened with flow outside of estuary channel, at point 5 and point 6. the current speed of pact is less than that of pa0 at point 5 and point 6 for both periods of northeast and southwest monsoon. figure 6. comparison between different cases for wave height in southwest (a) and northeast (b) monsoon and for current velocity in southwest (c) and northeast (d) monsoon. asian review of environmental and earth sciences, 2024, 11(1): 1-9 8 © 2024 by the authors; licensee asian online journal publishing group 3.5. seasonal morphological change seasonal variations in seabed topography are shown in figure 7. during the 1 month in southwest monsoon season, the seabed at thuan an estuary area has a little fluctuation. the strongest impact is in the channel area of the pact with an erosion and deposition of about -0.15m. with the existing condition, the sedimentation is very small and insignificant. during the northeast monsoon: large waves combined with stronger floods flowing from the river, the seabed of thuan an estuary fluctuates quite strongly. a sand bar has been formed at the river mouth with an accumulation of up to 0.8m, affecting navigation and flood drainage in the existing condition pa0. in case of structure measure, the average channel bed accumulation is about 0.4m, alternating with erosion about -0.4m, thus the deposition layer in proposed structure is much less than that of the existing condition. this proved the efficiency of the proposed structure to reduce deposition in the estuary channel to promote the flood drainage and waterway navigation. figure 7. change of seabed during the southwest period in the conditions of existing pa0 (a), structure pact (b) and during the northeast period in the conditions of existing pa0 (c) and structure pact (d). 3.6. drainage the frequency 2% flood the flood drainage for sc3 with flood frequency of 2% are shown in table 2. water level and velocity are extracted at 12 locations along the river from thao long bridge to thuan an estuary (figure 8). the water level along the river is higher in the proposed structure scenarios than the water level in the existing condition. the maximum water level difference is at the estuary throat locations t7, t8, t9 (figure 8) by 16 cm. the increasing water level is from 10-12cm at locations t4, t5, t6, these locations are in lagoon area upstream of estuary throat. the water levels are not increased at locations in river and sea, ie. t1, t2, t3 and t11, t12. this means that the elongation of jetties has no effect to these locations. flow velocity is changed with different trends along the estuary. flow velocity is increased at locations t10, t11, t12 about 40 cm/s to 94 cm/s due to shrinking of width of estuary and are decreased at the rest locations (less than 18 cm/s) at throat of estuary due to the obstruction of higher water level. the increasing of velocity has promoting effect to dispose of sedimentation of the estuary channel meanwhile increasing water level at estuary locations is not much to threaten the bank of estuary. figure 8. sketch map of 12 locations with the conditions of existing and elongated jetties. asian review of environmental and earth sciences, 2024, 11(1): 1-9 9 © 2024 by the authors; licensee asian online journal publishing group table 2. a comparison of hydrodynamics between the conditions of existing and elongated jetties under the 2% river flood frequency. locations water level (m) flow velocity (m/s) pa0 pact different with pa0 pa0 pact different with pa0 1 1.67 1.67 0 1.55 1.55 0 2 1.24 1.24 0 1.84 1.84 -0.01 3 0.84 0.89 0.04 1.57 1.52 -0.05 4 0.42 0.52 0.1 1.22 1.16 -0.05 5 0.32 0.44 0.11 0.79 0.75 -0.05 6 0.23 0.34 0.12 1.12 0.97 -0.15 7 0.05 0.21 0.16 1.29 1.11 -0.18 8 0.06 0.21 0.16 0.87 0.79 -0.08 9 -0.01 0.15 0.16 1.15 1.11 -0.03 10 -0.09 -0.05 0.05 0.88 1.82 0.94 11 -0.09 -0.09 0 0.37 1.09 0.72 12 -0.09 -0.09 0 0.3 0.7 0.4 4. conclusions thuan an estuary is characterized by seasonal fluctuations of waterways channel and coastal beach. this estuary is wave-dominated lowland coasts. the coastal barrier is built from sand transported along the coast by wave-driven longshore sand transport. in the northeast monsoon season, river flow is small, tidal currents combine with longshore currents by waves to form strong longshore current with direction from northeast to southwest. in the southwest monsoon season the sand bar from the south side will expand to the north, causing sedimentation at the channel of the river mouth. the study proposes the elongation of 2 jetties to mitigate the sedimentation at thuan an estuary for enhancing flood drainage and maintain waterway navigation. on the basis of calculated hydrodynamic characteristics for this proposal, it is observed that the flood drainage insignificantly affected by the proposed measure. although the maximum water level increased at throat channel of the estuary is 16cm but the water level at other location in the river is not changed. a further study is, however needed to improve the result by investigating deeper into the sediment transport regime for whole year and longer period. the structures layout and the size of structures are also need to investigate to find an optimization of these parameters. the proposed structure measure has a good effect on reducing sedimentation at estuary channel in both southwest and northeast monsoon seasons through morphological modelling results. this proved the efficiency of the proposed elongation of 2 jetties structure event out this structure caused a little higher water level at some location in the estuary channel. references [1] c. k. nicholas and c. s. william, "inlet spits and maintenance of navigation channels," erdc/chl chetn iv-44, u.s. army engineer research and development center, vicksburg, ms, 2002. [2] t. h. nguyen, study of erosion and sedimentation processes for coastal and estuarine areas from quang binh to thua thien hue provinces taking accounts of upstream activities and propose counter measures for stabilization. hanoi, vietnam: national research project report coded kc08.16/16-20, 2020. [3] l. c. van rijn, principles of sedimentation and erosion engineering in rivers, estuaries and coastal seas, 600 p., incl. toolkit on cd-rom. the netherlands: aqua publications (www.aquapublications.nl), 2005. [4] t. h. nguyen, v. h. nguyen, and d. c. vu, "integration of remote sensing and gis to study erosion and accretion at estuaries and coastal zone in thua thien hue province," presented at the civil engineering conference in the asian region (cecar8), april 1619, tokyo, japan, 2019. [5] deltares, "delft3d-flow," simulation of multi-dimensional hydrodynamic flow and transport phenomena, including sediments user manual. version 3.04, deltares, delft, the netherlands, 2010. [6] national weather service, "noaa wave watch iii model data access," retrieved: https://polar.ncep.noaa.gov/waves/ensemble/download.shtml? [accessed 29 june 2023], 2023. [7] egbert and erofeeva, "ceoas, oregon state university, usa. osu tpxo tide models," retrieved: https://www.tpxo.net/. [accessed 29 june 2023], 2023. [8] l. c. van rijn, "unified view of sediment transport by currents and waves. i: initiation of motion, bed roughness, and bed-load transport," journal of hydraulic engineering, vol. 133, no. 6, pp. 649-667, 2007. https://doi.org/10.1061/(asce)07339429(2007)133:6(649) [9] l. c. van rijn, "unified view of sediment transport by currents and waves. ii: suspended transport," journal of hydraulic engineering, vol. 133, no. 6, pp. 668-689, 2007. asian online journal publishing group is not responsible or answerable for any loss, damage or liability, etc. caused in relation to/arising out of the use of the content. any queries should be directed to the corresponding author of the article. www.aquapublications.nl https://polar.ncep.noaa.gov/waves/ensemble/download.shtml https://www.tpxo.net/ https://doi.org/10.1061/(asce)0733-9429(2007)133:6(649 https://doi.org/10.1061/(asce)0733-9429(2007)133:6(649 