Assessment of Environmental Flow Requirements of Vishwamitri River, Vadodara, Gujarat

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Assessment of Environmental Flow Requirements of Vishwamitri River, Vadodara, Gujarat
  Assessment of Environmental Flow Requirements of Vishwamitri River, Vadodara, Gujarat P. D. Bhangaonar Assistant Professor !ivil Engineering De"artmentVadodara #nstitute of EngineeringVadodara, Gujarat, #ndia $.%. Patel Prin&i"alVadodara #nstitute of EngineeringVadodara, Gujarat, #ndia  Abstract  - Many countries, developing ones in particular,face a number of water-related challenges, including anincreasing demand for water on the one hand, and the need toallocate a share of water to maintain the functioning of freshwater-dependent ecosystems in a river basin on the other.This share is often referred to as “Environmental Flow”,“Environmental ater !e"uirement” #E!$, “Environmental%emand”. Thus environmental flows are a compromise betweenwater resources development and the maintenance of a river inecologically acceptable or agreed conditions. Managing theenvironmental flow is a comple& tas' because the change of "uantity occurs as the flow moves downstream ()* . Manymethodologies for determining these re"uirements have emergedin recent years. They are 'nown as environmental flowassessments #EF+s$ and may be conducted using a range of techni"ues, which differ significantly in the level of accuracy andinput information re"uired. n this paper, the efforts are made toassess the Environmental Flow !e"uirement #EF!$ in terms of ' natural Mean +nnual !unoff #M+!$ as well as long term EF-volumes for different environmental management classes for thestretch with ilol illage gauge station as a source station, in theishwamitri !iver, a tributary of the %hadhar !iver /asin,adodara, 0u1arat. The results for preliminary estimate of EF! are derived from the “0lobal Flow %atabase” available in theform of monthly discharges #in m 2 3s$ for duration )45)-6555within 0lobal Environmental Flow 7alculator #0EF7$ software.From the rapid preliminary environmental flow assessment, ithas been established that for maintaining the slightly modified tonatural ecological conditions in the river at the source site, theEF! should be 22 to 859 of Mean +nnual !unoff #M+!$ .:owever the derived results are to be recogni;ed upto immediatedestination site i.e. the site upto which physical, hydrological andwater "uality conditions in the river remains unchanged.  Index Terms  (   Environmental Flows )E*flows+,Environmental Flow Assessments )EFAs+,Vishwamitri River, GEF! %oftware #. #  -RD/!-#  ver half of the world0s a&&essi1le surfa&e water is alread2a""ro"riated 12 humans, and this is "roje&ted to in&rease to anastounding 34' 12 5456 )Postel et al., 7889: Postel, 788;+.<ater resour&e develo"ments su&h as im"oundments,diversion weirs, inter1asin water transfers, run*of*river a1stra&tion and e="loitation of aquifers, for the "rimar2 usesof irrigated agri&ulture, h2dro"ower generation, industr2 anddomesti& su""l2, are res"onsi1le worldwide for un"re&edentedim"a&ts to riverine e&os2stems, most of whi&h emanate fromalterations to the natural h2drologi&al regime )Rosen1erg etal., 5444+. >ani"ulation of the flow regimes of rivers, to "rovide water when and where "eo"le need it, has resulted ingrowing deterioration in the &ondition )health+ of riverinee&os2stems. -here &an 1e loss of fisheries: loss of landthrough 1an &olla"se and &onsequent redu&tion in the life*s"an of in*&hannel dams: in&reasing levels of water "ollutionand lined health "ro1lems, loss of rare s"e&ies, river featuresand ha1itats, "roliferation of "est s"e&ies, loss of there&reational and s"iritual values of water s2stems, and loss of river resour&es for ri"arian "eo"le reliant on them for su1siden&e. Re&entl2 in #ndia, there is an in&reasing awarenessof the need to reserve some water along a river to ensure the&ontinued fun&tioning of e&ologi&al "ro&esses that "rovidemu&h needed goods and servi&es for human use, andmaintenan&e of 1iodiversit2. Environmental flows are oftendefined as the quantit2, qualit2 and timing of water flowsrequired for sustaining freshwater and estuarine e&os2stemsand the human livelihoods and well*1eing that de"end onthese e&os2stems. -hese flows ensure a flow regime &a"a1leof sustaining a &om"le= set of aquati& ha1itats and e&os2stem "ro&esses and are referred to as ?environmental flows@,?environmental water requirements@, ?environmental water demand@, E*flows et&. -he Vishwamitri River is a seasonal river and a tri1utar2 of Dhadhar River Basin. -he river &eases flowing in dr2 seasondue to diversions of river water at its u"stream. For ensuringthe ?2ear*round flows@, e=a&t h2drologi&al requirements interms of Environmental flows are therefore the maintainedneed to 1e &arefull2 assessed. <ith this o1je&tive, in this "a"er the efforts are made to assess the environmental flowrequirements of Vishwamitri River at Pilol Village River Gauge %tation.##. % -/D  A REA  -he Vishwamitri River srcinates from Pavagadh hill ata1out 55C40 latitude and 3C60 E longitude. -he srcin of Vishwamitri River from the Valle2s of the Pavagadh hill isshown in Figure 7.  F#G.7  R#G#   F  R  #VER   V #%<A>#-R# -he Vishwamitri is a seasonal river and the flow in river isver2 low e=&e"t in monsoon. >ean dail2 dis&harge valueswored out for data availa1le at Pilol river gauging station at on*Bridge site near village Pilol. Figure 5 shows the&umulative h2drogra"h of River Vishwamtri for dis&hargevalues o1served at Pilol Gauging %tation. From the gra"h,seasonal nature of the river &an 1e o1served. River mainl2flows signifi&antl2 in the month of $ul2, August, %e"tem1er and &to1er. F#G. 5 !/>>/A-#VE DRGRAP FR R#VER V#%<A>#-R# Vishwamitri watershed is a "art of Dhadhar River Basin.ength of Vishwamitri is a""ro=imatel2 779 m withlongitudinal slo"e of 7 644 to 7 344. -he leaf sha"ed<atershed of Vishwamitri is having geogra"hi&al area of a""ro=imatel2 7564 m 5 . River is diverted at its u"stream toAjwa Reservoir. Ajwa Reservoir is a major sour&e of driningwater for Vadodara !it2. -he River flows from East to westthrough the &it2 of Vadodara. Vadodara &it2 &overs the major area of the &at&hment of Vishwamitri River. #n Figure C, the watershed of Vishwamitri river derivedfrom Google Earth );;;+ is shown along with the mi&rowatersheds )in different &olours+ &ontri1uting the river. %ur2aRiver and $am1uva River are two tri1utaries to VishwamitriRiver on its u"stream and downstream sides res"e&tivel2.A"art from that major stormwater drains from Vadodara !it2are draining released water to Vashwamitri River. F#G/RE C<atershed of River Vishwamitri ###. F #ED   B%ERVA-#% -he various Point %our&es of "ollution as well as on Point%our&es of Pollution were o1served while monitoring thestret&h of Vishwamitri River a&ross Vadodara &it2. -hesesour&es in&lude sewage effluent dis"osal, #ndustrial effluentdis"osal, land fill, slums, et&. #n the a1sen&e of a""ro"riatesewage &olle&tion and waste water treatment "lants, the river has 1e&ome the main &olle&tor drain. Ra"id ur1aniHation has "ut tremendous "ressure on the water su""l2 distri1ution inthe &it2. As it "asses through the &it2, the river is 1iologi&all2dead and made of heavil2 "olluted sewage water that "otentiall2 endangers the downstream water usersI health. Atdownstream of Vadodara !it2, the Dhadar River after flowing;3 m re&eives Vishwamitri tri1utar2 from right 1an near Pingalwada village. At this jun&tion the water of River Vishwamitri was o1served more 1la&ish than River Dhadhar )Refer Figure +  J5K .    F#G/RE Vishwamitri River merging with Dhadhar River  Flow in Vishwamitri is highl2 dis&ontinuous. River isdrained through s2"honed 1elow amarda >ain !anal near Aasoj Village. -he water from Vishwamitri River is divertedinto Ajwa Reservoir )as "er seasonal requirement+ throughAjwa feeder &anal near Aasoj Village. Various streams fromdifferent water 1odies at u"stream merge with VishwamitriRiver from 1oth its left side and right side. %ur2a and $am1uvatri1utaries, at u"stream and downstream of the river res"e&tivel2, also &ontri1ute dis&ontinuities to Vishwamitri.Various storm water drains )Laans+ of Vadodara &it2 alsodis&harge the storm water to the river.#V.  E!E%%#-   F  % -/D #t is o1served that river is "olluted due to anthro"ogeni&a&tivities. >oreover, the flow of river is ver2 less most of thetime in a 2ear. #t is need of hour to tae ma=imum 1enefits of river water 12 ensuring required quantit2 and qualit2 of water flow to sustain life. -his &an 1e initiated through ra"id "reliminar2 environmental flow assessment of VishwamitriRiver. V. > E-D%   FR   E* F<  A %%E%%>E-% -he majorit2 of environmental flow methodologies &an 1egrou"ed into four distin&t &ategories 2drologi&al>ethodologies, 2drauli& Rating: a1itat %imulation>ethodologies: olisti& >ethodologies JCK .  A.Hydrological Methodologies -hese methods are also nown as fi=ed*"er&entage or loo*u"ta1le methodologies. -hese methods are &onfined to the use of e=isting or modelled flow data1ase, usuall2 in the form of naturaliHed, histori&al monthl2 or dail2 flow re&ords, with anassum"tion that maintaining some "er&entage of the naturalflow, often termed as >inimum Flow, will "rovide thesustaina1le solution to the "res&ri1ed environmental issueslie maintenan&e of freshwater fisher2, other e&ologi&alfeatures, or river health at some a&&e"ta1le level. -hesemethodologies are generall2 used for the "lanning level andhave 1een a""lied widel2, 1oth in develo"ed and develo"ing&ountries. -ennant method is widel2 used h2drologi&al method whi&haddresses environmental flow for fish, wildlife, re&reation andrelated environmental resour&es. Another &ommon h2drolog2* 1ased methodolog2 is Flow Duration !urve Anal2sis )FD!A+where Flow Duration !urves )FD!s+ dis"la2 the relationshi" 1etween dis&harges and the "er&entage of time that it ise=&eeded.  B.Hydraulic rating/ Habitat retention methodologies -hese methodologies are also nown as a1itat Retentionmethodologies. -hese methodologies were develo"ed tore&ommend instream flows for e&onomi&all2 im"ortantsalmonid fisheries in /%A. -hese methodologies use sim"leh2drauli& varia1les, su&h as wetted "erimeter or ma=imumde"th, velo&it2 et&. usuall2 measured a&ross, single, limitingriver &ross*se&tions )e.g. riffles+ for an Environmental Flowre&ommendation. C.Habitat Simulation Methodologies -he2 are also nown as >i&roha1itat or a1itat >odellingmethodologies. -hese te&hniques attem"t to assess EFRs onthe 1asis of detailed anal2ses on the quantit2 and suita1ilit2 of instream "h2si&al ha1itat availa1le )in&luding 2drauli&s+ totarget s"e&ies or assem1lages under different dis&harges )or flow regimes+, on the 1asis of integrated h2drologi&al,h2drauli& and 1iologi&al res"onse data.  D.Holistic Methodologies olisti& Environmental Flow >easurements have &ontri1utedgreatl2 to the field of environmental flow assessment in re&ent2ears. olisti& methodologies are a&tuall2 framewors thatin&or"orate h2drologi&al, h2drauli& and ha1itat simulationmodels. -he2 are the onl2 EFA methodologies that e="li&itl2ado"t a holisti&, e&os2stem*1ased a""roa&h to environmentalflow determinations. A glo1al review of E*Flows Assessment methodologies 12-harme )544C+ reveals that there are more than 544methodologies, few are ver2 qui& modeling or e=tra"olationmethods, requiring minimum e=tra wor: others require 2earsof fieldwor and team of s"e&ialists from various dis&i"lines.-his "a"er attem"ts to e="lore the use of 2drologi&al>ethodologies with &on&e"t of ?%hifting of Flow Duration!urves@ to estimate the "reliminar2 requirements of   Environmental flows of Vishwamitri River at Pilol villageriver gauging station.V#. ! #!E   F  > E-D -he main driving issues for the &hoi&e of method are s&o"ing, 1asin "lanning, im"a&t assessment and river restoration JK .  A.Methods to be used for Scoing! For the national assessments of man2 river 1asins need to 1eassessed, a ra"id h2drologi&al methods su&h as a loo*u"ta1le, FD!A method or -ennent method would 1e mosta""ro"riate.  B."or Basin #lanning!   Basin s&ale "lanning involves the assessment of environmental flows through an entire river 1asin. #n this &ase,assessment ma2 1egin with use of loo*u" ta1les to home*in&riti&al sites. -hen a des*to" a""roa&h su&h as Range of Varia1ilit2 A""roa&h )RVA+ would 1e a""ro"riate. Further investigation &omes under heading of ?#m"a&t Assessment@. C."or Imact Assessment!   <hen environmental flow assessment involves im"a&tassessment and mitigation of s"e&ifi& flow modifi&ations su&has dams or major a1stra&tions or where there is a singleim"a&ted site, "arti&ularl2 where water allo&ation is highl2&ontentious and might lead to a "u1li& inquir2, it is a""ro"riateto mae initial assessments of the im"a&t around the 1asinusing a des*to" method 1efore more s"e&ifi& fun&tionalanal2sis or ha1itat modelling is undertaen.  D."or $i%er restoration!   -he holisti& a""roa&hes allow assessment of the 1enefits of an2 restoration a&tivities, in terms of enhan&ed fun&tioning of all "arts of the river e&os2stem and there12 restoring the river to it its natural state. Ph2si&al ha1itat modeling has also 1eenused in several &ountries to assess the effe&tiveness of mor"hologi&al restoration s&hemes.V##. ! AEGE%   -  A %%E%%  E*F < Vishwamitri River is diverse in terms of its "h2si&al,h2drologi&al and water qualit2 as"e&ts so ever2 small stret&hshall 1e thoroughl2 e=amined to identif2 homogeneit2 of river River is altered 12 several anthro"ogeni& a&tivities so it is&hallenging to o1serve these a&tivities at mi&ro level. For thesame the entire river &an 1e studied into segments and thosesegments &an 1e e=amined individuall2 for Present E&ologi&al%tate )PE%+ through anal2Hing different water qualit2 as wellas h2drologi&al "arameters. -he river flow is ver2 un&ertain,un"redi&ta1le and having a1ru"t &hanges throughout the 2ear,so it 1e&omes a &hallenging tas to anal2se the h2drologi&al "arameters. -he h2drologi&al data of the river is s&ares sovarious &om"utational methods for stud2ing watershed&hara&teristi&s are essential and required. River is "assingthrough areas having different and use and and !over  "attern so utmost frequent field visits are required. V###. A %%E%%>E-   F  E* F<  R  EM/#RE>E-%   B  FD!% #F-#G  > E-D For 1asin s&ale "lanning of the Vishwamitri River, theenvironmental flow assessment &an 1e initiated using Glo1alFlow Environmental Flow !al&ulator )GEF!+. GEF! is asoftware "a&age for desto" ra"id assessment of Environmental Flows. -he software is develo"ed 12#nternational <ater >anagement #nstitute )#<>#+, %ri ana.GEF! has fa&ilities to Hoom on arrive 1asin, &al&ulate avariet2 of h2drologi&al &hara&teristi&s, define or sele&t an2&ategor2 of e&os2stem "rote&tion, &al&ulate the asso&iatedenvironmental flow duration &urves )FD!s+ and time seriesand dis"la2 1oth. -he EF estimation te&hnique in GEF! isusing monthl2 time ste" series refle&ting ?natural@ Nunregulated flow &onditions and its &orres"onding FD!* a&umulative distri1ution fun&tion of flows. -he FD! isre"resented 12 73 "er&entage "oints on the "ro1a1ilit2 )O+a=is.   -he "ur"ose of Environmental Flow is to maintain thee&os2stem in some "res&ri1ed or negotiated &ondition, alsoreferred as desired future state, Environmental >anagement!lasses )E>!s+, a level of environmental "rote&tion. %i=E>!s are in&or"orated in GEF!, ranging from ?/nmodified@to ?!riti&all2 >odified@ as shown in -a1le #. -a1le*#Environmental >anagement !lasses )E>!s+ used in FD! %hifting >ethodE>!>ost iel2 E&ologi&al !onditionAatural Rivers with minor modifi&ationB%lightl2 >odified!>oderatel2 >odified. -he ha1itats and d2nami&s of the 1iotahave 1een distur1edDargel2 modified. A large loss of natural ha1itat, 1iotas and 1asi&e&os2stem fun&tions has o&&urred.E%eriousl2 >odified. -he losses of the natural ha1itats, 1iotas and 1asi& e&os2stem fun&tions are e=tensiveF!riti&all2 >odified. >odifi&ation has rea&hed a &riti&al level andthe e&os2stem has 1een &om"letel2 modified. #n the worst &ase,the 1asi& e&os2stem fun&tions have 1een destro2ed and the&hanges are irreversi1le. -his software wors on &on&e"t of shifting of referen&eFD! along the "ro1a1ilit2 a=is and there12 redu&ing thefrequen&2 of flow for desired E>!. -he differen&e 1etweenthe default shifts of the referen&e FD! for different E>!s isset to 1e one "er&entage "oint. -he anal2sis &an 1e &arried outeither using default )simulated+ glo1al flow data, with a s"atialresolution of 4.6 degree, or a user*defined file J6K . A "reliminar2 estimate of ' atural >ean Annual Runoff )>AR+ as well as long term EF*volumes )>!>+ required for different E>!s at Pilol Gauge station )55 4 50  and 3C 4 7C0E+at on*Bridge site near village Pilol esta1lished 12 %tate<ater Date !entre )%<D!+, Gandhinagar, Gujarat derived  from the ?Glo1al Flow Data1ase@ in the form of monthl2dis&harges )in m C Ns+ availa1le for duration 7847*5444, andresult is re"resented in -a1le*##. -a1le*##Estimate of ' atural >AR and long term EF*volumes )>!>+ ilol 0auge <tation9 =atural M+! EnvironmentalManagement 7lass+/7%EF85.822)>.)?.?@.86.AEF-olumes #M7M$EnvironmentalManagement 7lass+/7%EF9!EF 4.47C765.444C48.44457C7.444754.444;87.44473.444544.4444.7C48.44457C7.444754.444;87.44473.444544.444748.444757C7.444754.444;87.44473.444544.444748.44463.6446754.444;87.44473.444544.444748.44463.644C4.94474;87.44473.444544.444748.44463.644C4.94473.4445473.444544.444748.44463.644C4.94473.4448.C74C4544.444748.44463.644C4.94473.4448.C74.544748.44463.644C4.94473.4448.C74.545.7546463.644C4.94473.4448.C74.545.7544.7594C4.94473.4448.C74.545.7544.754.533473.4448.C74.545.7544.754.534.5C6;48.C74.545.7544.754.534.5C64.55C84.545.7544.754.534.5C64.55C4.575865.7544.754.534.5C64.55C4.5754.547884.754.534.5C64.55C4.5754.5474.78788.84.534.5C64.55C4.5754.5474.7874.7;588.884.5C64.55C4.5754.5474.7874.7;54.735 #O. ! !/%# From the result, it &an 1e found that higher the E>!,the more water is needed. From the Glo1al Data1ase of GEF! it is derived that for maintaining the slightl2modified to natural e&ologi&al &onditions in the river at thesour&e site, the EFR should 1e CC to 94' of >ean AnnualRunoff )>AR+. %o 4' to 93' of >AR &an 1e &onsideredas sur"lus to fulfil the demands of downstream users. -heavaila1le h2drologi&al data of re&ent 2ears &an 1ein&or"orated for more realisti& stud2 as GEF! &an also 1eused with user defined file as an in"ut to assess the E*flowrequirements.Ver2 less flow with signifi&ant anthro"ogeni& a&tivities&an 1e &onsidered as major res"onsi1le fa&tor for maingriver e&ologi&all2 and 1iologi&all2 dead. -he "resente&ologi&al status for a homogenous stret&h of the river interms of its "h2si&al, h2drologi&al and water qualit2 as"e&ts,ne=t to Pilol guage station &an 1e assessed 12 stud2ing allrequired "arameters. For the sele&ted stret&h, the desiredE>! &an 1e set 12 e="erts0 judgements. !onsidering PilolGauge %tation as a sour&e station, the E*flow requirements&an 1e in&or"orated u"to immediate destination site. EFA&an 1e &arried out for whole river. -he following a&tivities&an 1e &onsidered as a "art to allo&ate E*flows at "res&ri1edstret&h.7.2drologi&al anal2sis of entire watershed of Vishwamitri river to estimate the inflow andoutflow in river.5.-he Present E&ologi&al %tate )PE%+ of Vishwamitrishall 1e assessed regularl2 and a&&ordingl2 the E*Flows &an 1e maintained and released.
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