ARTIFICIAL RECHARGE AGAINST SEA WATER INTRUSION & SECURED GROUNDWATER AVAILABILITY IN THE COASTAL AREA OF VANUR TALUK, VILLUPURAM DISTRICT, TAMIL NADU

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1 ARTIFICIAL RECHARGE AGAINST SEA WATER INTRUSION & SECURED GROUNDWATER AVAILABILITY IN THE COASTAL AREA OF VANUR TALUK, VILLUPURAM DISTRICT, TAMIL NADU A PROJECT SUBMITTED BY AUROVILLE WATER HARVEST Centre fr Water Resurces Management Nvember 06 Aurville Water Harvest Naidu Huse - Kttakarai AUROVILLE Tamil Nadu, India Tel N : Telefax : harvest@aurville.rg.in Aurville Water Harvest Page 1/1 Nvember 2006

2 ARTIFICIAL RECHARGE AGAINST SEA WATER INTRUSION & SECURED GROUNDWATER AVAILABILITY IN THE COASTAL AREA OF VANUR TALUK, VILLUPURAM DISTRICT, TAMIL NADU Submitted by : AUROVILLE WATER HARVEST Prject crdinatin : Aurville Water Harvest Executive Directr : Mr. Gilles Bulict Requested funding amunt : 40,000 Eurs Timeframe : 12 Mnths 1. Summary The prject has fr bjective t recharge grund water thrugh artificial methds and allw fr larger irrigatin f lands frm surface water flw. The prject will be implemented in Vanur Taluk, where the grundwater resurces are seriusly depleting and threatened by sea water intrusin, wrsened by the Tsunami f December The prgram targets the Vanur sandstne castal aquifer, which is the main aquifer f the regin and surce f irrigatin fr the agriculture f Vanur blck. Mrever, this aquifer is als supplying the city f Tindivanam. Artificial recharging will be dne thrugh recharge wells, check dams and perclatin pnds in the catchment s area f the prject. Heavy mnsn rains are flwing thrugh the drainage netwrk and feed irrigatin tanks and pnds ver the area, while a very large part is nt cllected and finally lst t the sea. This large vlume can be harvested n site and benefit t the large ppulatin living there by allwing fr grundwater recharge and create new pprtunities fr surface irrigatin. Direct Beneficiaries and stakehlders are the inland ppulatin f pr farmers and the nearby castal ppulatin, but als Tindivanam twn ttaling 270,000 peple. 2. Intrductin & backgrund The castal area f Tamil Nadu is suffering f heavy ver explitatin f grundwater due t lack f awareness f the ppulatin n the limited resurces, but als because f a lack f management f the resurces. Thrugh time, this has created a heavy depletin f the grundwater and cnsequently a severe risk f seawater intrusin, which cannt be turned back nce ccurring during nrmal human time scale. The disaster caused by the Tsunami n the eastern cast f Suth India has wrsened the situatin by flding large area with saline water which perclated very fast in the fresh water resurces undergrund. Gd and secure water supply fr the inhabitants f the castal area is nt sufficient. This is affecting the livelihd f the ppulatin, but als the agricultural activities, the fertility f lands and finally may lead t a desertificatin f the area. Cnsiderable imprvement can be made by tapping the runff water cllected in the drainage netwrk but ging t the sea because f insufficient strage capacities. This massive vlume f surface water can be used fr grundwater recharge implementatin and als t create larger surface water irrigated areas. Backgrund infrmatin Aurville Water Harvest is wrking in the field f Integrated Water Resurce Management since In 1995, an increase f salinity started t be mnitred in mst f the aquifers f the area, including wells supplying drinking water. Accrdingly, Aurville Water Harvest was launched the 15 th f August 1996, t fight against the fast degradatin f water resurces and t develp hlistic water management apprach, including ppulatin mbilisatin and participatin. The internatinal twnship and the villages in and arund Aurville have develped a symbitic relatinship ver the years and ne f the beneficial interactins is thrugh water. These prgrams are cnducted in cllabratin with the stakehlders and with the supprt f the lcal authrities and researchers. It aims at facilitating integrated water resurces management, including urban/rural inter-despndency, in Aurville Bi-regin. Aurville Water Harvest Page 2/2 Nvember 2006

3 The prject is lcalized in the heart f a castal sub-watershed n the mst imprtant aquifer f the area, bth fr irrigatin and drinking water supply. The prject area is the natural recharge zne f the main aquifer f the regin, Vanur sandstne aquifer. This aquifer is severely threatened by ver explitatin and sea water intrusin. All this area suffers frm scarcity f water resurce and heavy risk f sea water intrusin inland. The actual grundwater table is seriusly depleting and the quality f water is badly affected by salinity. A balance needs t be maintained t prtect the sft water resurce. This can be dne by imprving the drainage system and the grundwater recharge. On this castal area, the gelgical set up is made f sandstne. N perennial river is flwing thrugh the area. Cnsequently men has created thrugh centuries a very reach netwrk f intercnnected drains, irrigatin tanks and pnds in rder t cllect rainwater and t allw fr surface irrigatin thrugh lnger perid. Thrugh time, and because f plitical decisins and fast increase f ppulatin, the traditinal structures were nt prperly maintained and large ersin ccurred because f heavy tree cutting. In the 60 s and 70 s, during the Green Revlutin, the Gvernment decided t give free electricity t farmers which in turn started t extract grundwater. The traditinal surface irrigatin structures were even mre neglected and at the same time n awareness was given t the farmed abut the fact that grund water is a limited resurces. I such a cntext, we bserve tday a large reductin f grundwater recharge because f bad infrastructure, defrestatin and land ersin, a reductin f the strage capacity and quality f the irrigatin tanks and pnds, tgether with a very fast develpment f grundwater extractin. A large amunt f water can be saved fr recharging the grund by cnstructing recharge structure alng the drainage netwrk, and made available fr surface irrigatin by develping new irrigatin channels. Additinal activities The selected area is hsting intense activities thrugh ther Harvest s prgrams f Integrated Water Management, where a lt f effrt is dne t imprve the irrigatin tanks and pnds, train the farmers n best irrigatin practices, alternate crps, rganic farming, but als address issues like sanitatin and drinking water. This is creating the necessary mbilizatin and awareness f the ppulatin in rder t reach sustainability. The cumulative and synergic effect f the 2 prjects will definitively generate a much strnger impact n the water resurces but als n the cncern, implicatin and benefits fr the ppulatin. 3. Aims 4. Objectives T save fresh water resurce T imprve grundwater recharge T prtect the castal area frm sea water intrusin inland T prtect the quality f the water fr the large ppulatin living n the castal area T allw fr larger irrigatin f lands thrugh surface water cllectin, at the demand f the farmers The brader bjective f the prpsal is t retard cntaminatin by salinisatin f the castal aquifer (which is the nly dependable surce f accessible water fr drinking and agricultural purpses) in the castal villages and t maintain the hydrdynamic balance f the grundwater with seawater. The initiatives taken within this prject will act n the glbal eclgical system. The prject aims at mdifying the natural resurces capacities as well as their usage. The actins implemented will directly imprve the water resurce situatin as the prject cnsiders envirnmental and infrastructure aspects, and targets all the parameters f the prblem. The scientific knwledge develped n the hydrgelgical cnditins f this regin Aurville Water Harvest Page 3/3 Nvember 2006

4 will help t define suitable and practical slutins. We will tackle the surface runff, thus leading t a maximizatin f rainwater harvesting capacities in the area, and large increase f grundwater recharge by apprpriate recharge structures n the waterways and in the fields. The rehabilitatin f the water cnservatin structures will cntribute as well t augment the aquifers recharge but als t use mre efficiently surface water fr irrigatin purpse. Furthermre, implementing better surface water management, irrigatin and agriculture practices thrugh ther activities cnducted in the area will reduce reliance n grundwater. 5. Cmpnents 1) Identificatin study Fllwing specific parameters, several sites have been identified n the field t build up check dams. The check dams will be cnstructed at places where the catchments basin drains a large amunt f water. The lcatin and the height f the check dams will be determined accrding t the vlume f water reaching the dams, accrding t the risk f fld fr the surrunding area, as well as cst benefit parameters. 2) Cnstructin f grundwater recharges structures 3 Check dams will be cnstructed in the main drains f the watershed 1 recharge pnd will be excavated 3 high capacity recharge wells with attached filtratin units will be build 6. Expected utcme Impacts n the envirnment and grund water resurces: An imprved recharge f the grundwater resurces will benefit t the grundwater resurce availability. A prper balance between sft water and sea water will be maintained, thus preventing the risk f a fast salinizatin f the area. Reductin f despndency n grundwater resurce. Imprvement f infrastructure setup Ersin cntrl Imprvement f drinking water cnditin fr the ppulatin living in the area: The water quality will be prtected and gd and secure water can be supplied t the surrunding villages in a sustainable way. Lcal farmers will be able t irrigate a large area ut f surface water The drainage will be imprved and the pllutin risks will be less: By stpping the water t fld in an unexpected way and remain stagnant in the surrunding f the villages, the ptential risks f water cntaminatin will be less. 7. Activities 1) Tpgraphic Survey 2) Engineering design 3) Engineering wrk Excavatin in drains and pnds Check dams cnstructin Strengthening the prtectin bunds. Drilling and Develpment f recharge wells Cnstructin f filtratin units Number f check dams: 3 - Vanur utlet channel - Anpakkam (Kaluvelly) utlet channel. - Anpakkam supply channel Number f pnds t excavate: 1 - Anpakkam Aurville Water Harvest Page 4/4 Nvember 2006

5 Number f recharge wells and filtratin units: 3 - Recharge wells: 2 - Filtratin units: 4 4) Mnitring The structures will be maintain and mnitred regularly in rder t evaluate their efficiency as recharging devices. This activity is anyhw nt budgeted under this particular prject but will be cvered as part f ur regular tasks in the biregin. The wrk will be cnducted in clse cllabratin with Public Wrk Department f Pndicherry and Tamil Nadu and in cnsultatin with the lcal authrities. The structures wherever required will be certified by a registered engineer with submissin t PWD. The lcal ppulatin will be invlved in the physical wrk wherever pssible. Aurville Water Harvest Page 5/5 Nvember 2006

6 Aurville Water Harvest Page 6/6 Nvember 2006