Engineering, Technology & Applied Science Research Vol. 8, No. 3, 2018, 2981-2984 2981 www.etasr.com Laghari et al.: Analysis of Hydrological Response Considering Climatic Variability A Hydrological Response Analysis Considering Climatic Variability Case Study of Hunza Catchment A. N. Laghari Energy & Environment Engineering Department, Quaid-E-Awam University of Engineering, Science & Technology Nawabshah, Pakistan W. Rauch Unit of Environmental Engineering University of Innsbruck Austria M. A. Soomro Civil Engineering Department, Quaid-E-Awam University of Engineering, Science & Technology Nawabshah, Pakistan Abstract—The hydrological response of mountainous catchments particularly dependent on melting runoff is very vulnerable to climatic variability. This study is an attempt to assess hydrological response towards climatic variability of the Hunza catchment located in the mountainous chain of greater Hindu Kush-Himalaya (HKH) region. The hydrological response is analyzed through changes in snowmelt, ice melt and total runoff simulated through the application of the hydrological modeling system PREVAH under hypothetically developed climate change scenarios. The developed scenarios are based on changes in precipitation (Prp) and temperature (Tmp) and their combination. Under all the warmer scenarios, the increase in temperature systematically decreases the mean annual snow melt and increases significantly glacier melt volume. Temperature changes from 1°C to 4°C produce a large increase in spring and summer runoff, while no major variation was observed in the winter and autumn runoff. The maximum seasonal changes recorded under the Tmp+4°C, Prp+10% scenario. Keywords-mountain region; Hunza catchment; melting contribution; water resources I. INTRODUCTION Pakistan is an agrarian country and its agriculture is mainly dependent on one of the world’s largest irrigation systems, the network of the Indus Basin (IBIS). The irrigation system is largely fed through the Indus River System (IRS) comprised of Indus River and its tributaries. Indus River and most of its tributaries originates from the greater Hindu Kush-Himalaya (HKH) region. The region is famously known as “the water tower of Asia”. This mountain region works as a large reservoir, seizing precipitation and retaining it till released into various tributaries of the IRS. This system connects to the other most important reservoir, groundwater, but also constitutes a source of recharge of aquifers in the plain areas of Indus basin. The river system discharges an annual average volume of 175 billion m3 which supports directly about 60% of total irrigation requirements, while the rest is provided through groundwater exploitation-which is already close to its maximum potential. Therefore, Indus basin is considered as a closed basin-due to the exploitation of the full potential of ground and surface water resources [1, 2]. Further burgeoning population, industrialization and urbanization will require a 30% more increase in water demand in the next 2 decades. Moreover, it is projected that climate change will further exacerbate the problem through changes in river seasonality, time of occurrence and peak flow volume in the mountain regions [3]. Earlier studies conducted over the Himalayan part of Indus basin projected that alteration in climatic parameters would result in modification of the hydrological cycle and consequently affect the quantity and quality of river flows [4]. Likewise, numerous other authors also supported the same conclusion in the European Alps [2, 5, 6]. They concluded that any change in climatic parameters may alter the snow and ice storage. This may result in change of both the time of occurrence and the flow volume of mountain tributaries, which may have severe repercussions on adjoining plain areas. This would eventually affect seasonal water availability. The change in seasonality may hamper development in the agricultural sector, including future planning and operation of hydrological installations. Due to heavily dependent on melting runoff, the upper region of Indus basin (part of HKH) is extremely sensitive to climate change [7]. Therefore, it is worth to scrutinize the hydrological response against climatic variability of the Hunza catchment which is not thorough studied. This study investigates the hydrological response of the Hunza catchment to a warmer climate through the application of the hydrological modeling system PREVAH. The developed scenarios are based on changes in (Tmp) ranging from 1°C to 4°C and in (Prp) ranging from -10% to +10%. II. DESCRIPTION OF THE STUDY REGION The Hunza catchment encompasses an area of some 14746 km2 within greater HKH region. Its altitude ranges from 968m to over 7500m a.s.l (Figure 1). Hundreds of peaks exceed 6000m elevation. One-third of the catchment area remains under permanent glacial ice fields with about 808.79km3 ice reserves. There are hundreds of glaciers, but the 15 largest ones, like the Hispar (521km2), Batura (336km2) and Khurdopin (205km2), dominate the hydrological flow regime. Figure 2 indicates the climatic conditions of the basin. The summer monsoon of the subcontinent has very little influence ov blo is v fee acc hig win the gla wa Fig run Hy cha me in aut mo rep app Engineerin www.etasr er the precipi ock monsoon very low and eding mostly cumulation. T gh in summer nter is very lo e total stream acier melting. arm and dry m Fig. g. 2. The 30 y noff computed at g III. M The PREVA ydrotope) mo aracteristics eteorological p soil types, l thors have s ountainous cat present mount plied to sim ng, Technology r.com itation regime rains. Therefo predominantly y the snow The temperatu and very low ow. Overall the flow regime. Accordingly months and less 1. Map of stu year average (19 gauge station (Da MODEL DEVELO AH (Precipita odel has been of mountain parameters and and use, cov successfully tchments [2, 5 tain region ch mulate the hy y & Applied Sci e, as its south ore, the precip y restricted to cover and ure regime v w in winter, th e ice melt con Temperature glaciers prov s water in wet udy area-Hunza ca 960-1990) of mo ainyor Bridge) for OPMENT AND A ation-Runoff-E n developed n regions, e d consider phy ver and topog applied the 5, 6, 9, 10]. D haracteristics, P ydrological re ience Research Lag hern borders m pitation of the o winter season the glacier varies signific herefore the fl ntribution dom controls the r vide more wa and cool mont atchment onthly (Tmp), (Pr r the Hunza catchm APPLICATION EVApotranspi to truly rep .g., variabilit ysical heterog graphy [8]. S model to v Due to its abil PREVAH has esponse of H h V ghari et al.: Ana mostly basin n thus r ice cantly: low in minates rate of ater in ths. rp) and ment iration present ty in eneity everal arious lity to s been Hunza catc data line the effi than resu very hyd clim clim 4°C cha TAB M ana par gen sen mo scen dec is o whi und sno to und scen pea con volu run -10 sno hum Vol. 8, No. 3, 20 alysis of Hydrol chment. The m a for the years ear Nash-Sutc calibration iciency is abov n 5.5%. The ults prove tha ry well. The d drological resp mate. The fut mate scenarios C temperature anges. BLE I. MOD Ti sp Overall results 19 19 Annual results 19 19 19 Monthly results 1 1 1 IV The hydrolo alyzed by asse rameters again nerated clima nsitivity of sno thy basis. It narios, snow creases in June observed in A ile maximum der warmer a ow melt durati April/June. T der higher pre narios, while ak snow mel nditions, incre ume but incre noff. This effec 0% to +10% owmelt runoff mid and dry s 018, 2981-2984 logical Respons model was dev s 1986-1988 an cliffe efficienc and validatio ve 85% and d e monthly an at model repro developed mo ponse of catc ture warmer s based on po e increase an DEL EFFICIENCY (C Calibration res ime pan Dev (mm) 986- 988 -35 986 -31 987 -23 988 19 1 -09 2 -01 3 -12 4 -03 5 08 6 -02 7 -21 8 -17 9 -11 10 15 11 11 12 07 V. RESULTS ogical sensiti essing snow m nst climatic va ate change sc ow melt agains is clearly in w melt runoff e/July. The ma April/May und decrease of a and humid co on from May/ The volume o ecipitation scen no significant t occurrence. ease in prec ease in tempe ct can be seen changes in f varies betwe scenarios. The 4 se Considering veloped and a nd 1990-1992 cy and volum on periods. T difference in f nd annual ca oduced catchm odel was then chment under climate is re ossible combin d -10% to + CALIBRATION AND ults V R2 Tim spa 0.90 1990 199 0.92 199 0.90 199 0.85 199 0.99 1 0.99 2 0.99 3 1.00 4 0.87 5 0.82 6 0.89 7 0.88 8 0.83 9 0.87 10 0.99 11 1.00 12 S AND DISCUSS vity of Hun melt, ice mel ariability thro cenarios. Fig st various deve ndicated that f increases i aximum increa der warmer an about 45mm i ondition scena /July is shifted of peak snow narios and vic t effect observ In case of cipitation will erature will tri n over a Tmp + precipitation een 5 mm to e monthly sno 2982 g Climatic Varia applied to avai . Table I show metric deviatio The mean an flow volume is alibration/valid ment character n applied to a r a future wa epresented thr nations of a 1° +10% precipit D VALIDATION) Validation results me n Dev (mm) 0- 92 -41 0 90 -36 0 91 34 0 92 -39 0 -11 0 -08 0 -13 0 -06 0 -10 0 20 0 06 0 -11 0 13 0 0 -11 0 -01 0 2 -09 0 SION nza catchmen lt, and total ru ough hypotheti ure 3 shows eloped scenari under all ado in April/May ase of about 2 and dry condit s observed in arios. The cu d one month e melt is incre ce versa unde ved over timin humid and l grow snow igger a faster +4°C scenario n, where mo o 10 mm bet ow melt varia ability ilable ws the n for nnual s less dation ristics assess armer rough °C to tation s R2 0.87 0.90 0.85 0.85 0.98 0.99 0.99 0.99 0.86 0.69 0.92 0.90 0.74 0.85 0.99 0.99 nt is unoff ically s the os on opted and 25mm tions, June urrent earlier eased er dry ng of drier wpack melt o with onthly tween ations bet sno con con ref and cur eff sho gla inc Fig bas TA mo inc Ho inc are com sce Engineerin www.etasr tween the two ow melt contri Table II indi ndition (Tmp ntribution in ference contrib d humid con rrent snowme fect of differen own in Figur acier melt run creases linearly g. 3. Influence sis from (April to ABLE II. INFL SNOWMELT RU 1992) Climatic Sc Prp. Sc. - + Tmp. Sc. + + + C o m b in ed S ce n a ri o s Tm Prp Tm Prp Tm Prp Tm Prp Tm Prp Tm Prp Under all th onths earlier creased flows owever, under creased, thus s ea, resulting mparatively pr enarios. Figur ng, Technology r.com o scenarios ha ibution in tota icates that un p+4°C, Prp- total stream bution of 40.4 ndition (Tmp elt contributio nt combined s e 4 which cl noff starts earli y with increas e of climatic scen July) for 1990-19 LUENCE OF CLIM UNOFF, GLACIER M enario % co r Ref. mean annu snowm t (40.4% 10% 36.2% +10% 44.3% +2°C 38.3% +3°C 36.9% +4°C 35.4% mp+2°C p-10% 34.4% mp+2°C p+10% 42.1% mp+3°C p-10% 33.0% mp+3°C p+10% 40.5% mp+4°C p-10% 31.7% mp+4°C p+10% 38.9% he adopted sc than existing s each month r humid cond snow cover re in late sta roduces lower re 4 supports y & Applied Sci ave drastic effe l stream flow. der the adopt 10%) scenar flow reduced % to 31.7%, w p+4°C, Prp+1 on just reduc cenarios on gl early demons ier under all w ing temperatu narios on snow m 992 MATIC SCENARIO MELT RUNOFF, AN ontribution to reference* . n al mel %) Ref. mean annual ice melt (73.3%) % 74.9% % 71.8% % 89.9% % 98.9% % 108.0% % 91.4% % 88.5% % 100.2% % 97.5% % 109.4% % 106.7% *mean a cenarios, glaci conditions ( h under all ditions, the sn emains a bit lo art of glacie r glacier runof s this fact, w ience Research Lag fect on mean a ed warmer an rio, the snow d from the c while under w 0%) scenario ced to 38.9% lacier melt run trates that mo warm scenario ure. melt runoff on m OS ON MEAN A ND STREAM FLOW % change to reference* Ref. mean annual stream flow (--) -0.7% 0.8% 18.5% 28.2% 37.7% 16.6% 20.4% 26.1% 30.2% 35.6% 40.0% annual value: 639.5mm ier melting st (June) and pr adopted scen nowpack volu onger over gla er melting, w ff than dry con where the mo h V ghari et al.: Ana annual nd dry wmelt current warmer o, the %. The noff is onthly os and monthly ANNUAL W (1990- tarts 2 roduce narios. ume is aciated which ndition onthly glac Prp 10% tem mon glac ado scen whe cur Res mel wou bee ran pre ann Tab TAB cha con for 6.9% +0. war tem sub flow infl volu reco amo mon thei infl P Tm Vol. 8, No. 3, 20 alysis of Hydrol ciers melt run p) are compar % decrease in mperature linea nths. Monthly cier melt contr opted scenario nario produce ere mean ann rrent reference sults show tha lt runoff. In uld result in gl The result of en shown in F nges between cipitation have nual stream fl ble III. BLE III. INFL ON MEAN SEASO Τhe change ange mean sea ntribution (1.7% spring, 67.7% % for autumn 8%. However rmer climate mperature sign bsequently incr w. This can b luence of tem umes. The h orded in Ma ount backed nthly flows. T ir significant luence over s Climatic Scenar rp . Sc. -1 +1 mp. Sc. +2 +3 +4 C o m b in ed s ce n a ri o s Tmp Prp Tmp Prp Tmp Prp Tmp Prp Tmp Prp Tmp Prp 018, 2981-2984 logical Respons noff under hum ratively lower n Prp). It is arly increases y glacier melt r ribution to tota os, warmer a es highest in nual glacier m e contribution at the rate of the long run lacier depletio f variation in P Figure 5. As 200mm to 25 e very little im low volume. LUENCE OF HYPOT ONAL STREAM FLO in precipitati asonal flow con %) to 1.5-1.8% % to 66.9-68.6 n, while annua r, the major im change scen nificantly incr reased glacier be seen in Fig mperature cha highest increas ay-June period with earlier The early star contribution i stream season rio Seas Winter Ref. (1.7%) 10% 1.5% 10% 1.8% 2°C 1.9% 3°C 2.2% 4°C 2.5% p +2°C -10% 1.6% p +2°C +10% 2.1% p +3°C p-10% 1.9% p +3°C +10% 2.4% p +4°C p-10% 2.2% p +4°C +10% 2.8% 4 se Considering mid conditions than dry con also projecte s glacier melt runoff increas al stream flow and drier (Tm ncrease in gla melt contributi n 73.3% to temperature c n, warmer and on and retreat. Prp on month the average 50mm annual mpact over mo The effect ca THETICAL CLIMAT OW (1990-1992) ion from +10 ntribution from % for winter, 2 6% for summe al change will mpact has be narios, in w rease glacier melt contribu gure 6, which ange on mon ses in total m d, where inc glacier melt rt of snow an in total stream nality (Tables sonal % contribu r ) Spring Ref. (24%) 24.5% 23.5% 34.4% 40.0% 45.6% 35.1% 33.8% 40.4% 39.6% 45.9% 45.4% 2983 g Climatic Varia (+10% increa ndition scenari ed that increa t runoff in va ses significantl w volume. Und mp+4°C, Prp- acier melt ru ion increased 106% (Table controls the gl d dryer condi ly stream flow basin precipit lly, the chang nthly, seasona an be observe TE CHANGE SCEN 0% to -10% m current refer 24% to 23.5-2 er and 6.6% to l be around -0 en observed u which increase melt runoff- ution in total st h demonstrate nthly stream monthly flow reased snow causes a surg nd glacier mel m flow has a m II-III). Chang ution to referenc Summer Ref. (67.7%) Au R (6. 66.9% 6 68.6% 6 74.8% 7 78.2% 7 81.5% 8 73.2% 6 76.5% 8 76.6% 7 79.8% 8 80.0% 7 83.1% 8 *mean annual value: 6 ability ase in ios (- ase in arious ly the der all 10%) unoff, from III). lacier itions w has tation ges in al and ed in NARIOS will rence 24.5% o 6.3- 0.7 to under es in - and tream es the flow s are melt ge in lt and major ge in ce* tumn Ref. .6%) .3% .9% .4% .8% .1% .7% .0% .1% .4% .4% .8% 39.5mm (Tm con 46 cha tem sum (Tm no flo Fig July Fig to J Fig to J tem wh enh Th wa nut run dem wi con Engineerin www.etasr mp) from 2°C ntribution from % for spring, ange was ob mperature sens mmer months mp) from 2°C significant im ows. g. 4. Influence y) glacier melt ru g. 5. Influence July) stream flow g. 6. Influence July) stream flow The change i mperature) ha here change hanced averag he maximum i armer and hu tshell, the ma noff as comp monstrates tha ll be deplete nclusions can ng, Technology r.com C to 4°C wi m current refer , 68% to 75-8 bserved in a sitivity is obse s. In this pa C to 4°C still s mpact was ob e of climate chan unoff (1990-1992) e of precipitation (1990-1992) e of temperature c (1990-1992) in spring and ave drastically in (Tmp) fro ge annual strea increase of ab umid scenario aximum effec pared to snow at if temperatu ed and retrea be drawn for y & Applied Sci ill increase m rence contribu 81% for summ autumn and w erved to be lim articular catch seems below m bserved over nge scenarios on ) changes on magn changes on magn summer flows y increased m om 2°C to am flow from bout +40% is o (Tmp+4°C ct is observed w and total ru ure continues t ated in the r the dry seaso ience Research Lag mean seasonal ution (24%) to mer. No signi winter flows. mited to sprin hment, variati melting point, autumn and w n the monthly (A nitude of monthly nitude of monthly s (due to incre mean annual f 4°C have lin +18.5% to +3 observed und , Prp+10%). d over glacier unoff. This c to grow, the gl long run. S on. However, t h V ghari et al.: Ana l flow 34%- ificant . The ng and ion in hence winter April to y (April y (April ease in flows, nearly 37.7%. der the In a r melt clearly laciers imilar this is rev tem catc scen cha run in g leav par to a sign The and pro stre the fact this incr [1] [2] [3] [4] [5] [6] [7] [8] [9] Vol. 8, No. 3, 20 alysis of Hydrol ersed in the c mperature. This study an chment again narios. It is co ange in temper noff and subse glacier runoff ve a catalyst e rticular catchm a large increa nificant chang e maximum se d humid con oduce about 4 eam flow volu long run, th tors in glacier s could be the rease in tempe J. Briscoe, U. Q University Pres A. N. 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