Delineation of Ground Water Recharge Zones in Hard Rock Terrain of Tamil Nadu

Ground water resources diminish at alarming rates in hard rock regions as it is the primary source of irrigation as well as domestic purpose. Periodic replenishment of ground water in these areas is only through rainfall. Delineation of potential groundwater recharge zones in hard rock areas is of vital importance to enhance the recharge. Conventionally, suitable zone for groundwater recharge is deciphered using hydrogeological, geophysical and geomorphological maps, which is often time consuming and uneconomical. But, the analysis of unconfined aquifer response in terms of rise in water level due to precipitation in hard rock areas is one of the rapid and cost-effective methods. Cross-correlation of rise in water level and precipitation is established for Parambikulam-Aliyar-Palar (PAP) basin of TamilNadu, India to delineate groundwater recharge zones. The entire area is classified into various recharge zones depending on coefficient of correlation. Thus, decisions on construction of recharge structures / optimal pumping in these areas can be decided for sustainable ground water resource management to meet future demands.