River-aquifier interaction in little Jamuna river catchment in the northwest region of Bangladesh

Abstract

One ollhe major recenl concerns in the 'Jorthwesl r~gion of Uangbdesh is drying HI' uf a large numbcl' of riVeT\ and ,milll waleI' bodies. \\,hich has a dir~cl lmpael on lhe ccol"gy andlhe envmlllmclli. Small nHrs such a, PunMvoba, Lillie .lamuna. Dhepa, Till", and Go\'esh,m lhal uscd to be pcrcnnial inlJalLlTesomc twenty years ago lire no", lepllrlcd to be completely drying "LIt in the dry season. Cl~arly an improvcJ under,>landing of th~ ri,-er and groundwatcr is needed to expluin lhe change in ,udacc w,ner a" ailability, and 10 assess the response 0 I',lrc'mn now to n ucluations or change in ground watcl' level. In this study. I ,illk Jamuna ri\Tr calchmcnt in lhc North\\ c.,l region wa, ,clected a' lhc study ,Ir~u. Th~ \ludy foll{)\\,ed a lechll('-sncial approHch lu chal'a~len/c lhe sUl'filce \\aler and ground watcr ,:"lems and their llllcraclions in (he sludy area. Te~hnical analy,i, mainly indudcd a qrkl)' of an~lyli~al approaehe,. ~.g. lilhologi~al analysis. hydrograph anal)sis, flow duration cup.e, i>a<,cnow separalll1n, Il'cnd ~mtlv,i, and eOlTelalLon regrc,;sion ,malysis, T",o ,,,cial in\'eSligallOn mcthods \\,ere conducwJ III lhc study area: th~ lirst onc in\'ulvcd a qneSlionnairc survey \\'llh a vicw 10 finJing ont peopk', pet'cel'lHln abont lhe slalus of Slream tlow deplelion and it, po"ibk causes. impael, and mitigation mea,l.Irc" and lhe ~ceond melhod lllvol\'cd purp0'lve imcrviewo along a 17,5 km Ilretch along lhc l.itlie Jam una rivet' wiIh (h~ ehicf 0bjeel i\'e "f ("llafiICl~rl/ing lhe spalial \'anation in ,lream and aquifer 'yslcm ~nJ lheir mlemClion. Th~r~ haw b~en ,ui>;;lamial r~d\lClLOnSin slream nt'w in the df) irrig~tion month" Wilh r~dlletion of (l"ws ranging Ii'olll 40% to 70% ovcr a period or 30 ycnr" Al lhe .\am~ limc. Ibere b", been ,I marked dccreasing lr~nd in the dry ,>caSOnminimum ground,vllier kvel" There i, dircel ~onncclion belwecn the ri,Tr and underlYlllg aquifer, Th~ interacli"n bctween ri",:r and gl'Ound"atcr i, the 'lrongest elose lo lhc river, l'elled~J in a high wrrelation coe llicienl of O.R14 ~l a di,lune~ 0 f 2 km. It was found lhal Ihere is :I lag llllle in Ihe rclponse helwc~l\ thc gl'ollndwaler alld ,urr~ce waler. Slrong ri\'~raq\ lifer illl~ra~lions were Immd cven al Weatct' di'>lance, af1er a 1ag"lime 01' 2 1" 3 nWlIlhs. This w~s ldleclcd in a high eorrc!alion ~ocffici~llluj 0 760 at R km fmm lh~ ri,n ~n~r a lag lime 01' 3 month" 1.I~nce il i, iml'0llanl tn r~~<1gLlizeIh~ Jcla:H'd rl'sponse i>el"ecn g,oundwalCr 1c,,~1and river in analping lhe inl~rilCli{)n betw~~11 VlI surface waler and groundwater. and hence con",la the effect of irrigation pumping on stremn Ilow depletion even in areas rcJ:lli\ely lar from the ri\'er. Thn~ has been a 8harp declining (rend m the bJsellow of the river, with basel10w dedining by 50% io 90% in the dli' ~~a,ol\ month, of' January to l\plil oVCra period 01 30 }~ar<;, RainEdl diltnbution WilS1"'[ found to hilVt'play cd any milior rolL in aiTccting b''''cmdwatcr le\'els and hence streilm 1]",,", It is the imgatioll dc\'elopm~nt that hJ\'e ulle~[~d j!raduallowering of the groundwatcr level, ",hieh in turn caused reduction of bilse Ilow and hence ,tream flo'" i~ th~ t1ry "cason months. Th~ problem of'nvcr drying \lP hatl started ,i~~e 1990-9l; howewr, rcecllt trend hilS bcen the qart of the problem in carlier part "I the dry ,elison, 'I he flow depl~tion of river> anti reduction in waler bodies hil\e had n~gati\'e impacts on thc envmmmcL1wl eco>y~lcm. \vith man} of the 10Cill Ii,h species ,tilr(~tI 10 dis~ppearing, and th~ mignilory hirds gctting lo\\,er in number.