Evaluation of technical efficiency of recharge shaft using tracer techniques and groundwater modelling application to oddanthangal tank

Abstract

Due to erratic nature of rainfall the surface water sources are drying up leading to more dependence on groundwater and thereby artificial recharging of groundwater is gaining importance When impervious layers overlie deeper aquifers the infiltration from surface cannot recharge the groundwater under natural conditions Artificial recharging is the only possible way and though many methods are available recharge shafts are best suited for this purpose Recharge shafts are structures similar to a tube well but with a purpose of augmenting groundwater by pumping in treated surface water Therefore a recharge shaft constructed in Oddanthangal irrigation tank in Walajabad block an over exploited block Kancheepuram district of Tamilnadu was selected for the study and its performance has been evaluated Geophysical studies for aquifer mapping are necessary to understand the subsurface formation The study was carried out at 10 points in the study area and from the VES curves obtained it is observed that the top 10 m to 13 m is weathered and fractured top soil where groundwater is stored and below this depth massive Charnockite or Granitic Gneiss exists up to 105 m approximately newline