Impact of Groundwater Conservation Structure in Hard Rock Area - A Case Study of Gaurelli Micro Watershed, Yacharam Mandal, Ranga Reddy District, Andhra Pradesh

摘要

During the rainy season, the phreatic aquifer is recharged and gets saturated fully or partially depending on rainfall intensity and hydrogeological conditions. In due course of time, the groundwater flows out of watershed and gets depleted during subsequent months. As a result, groundwater may not be sufficient to meet the demand during the period of greatest need. To meet such situation, it is necessary to arrest the sub-surface outflow and conserve groundwater to meet the peak requirements. Construction of sub-surface (sub-surface dam) barrier across the stream at suitable location stops/obstructs the groundwater flow in the watershed. One such subsurface dyke was constructed across a second order stream in a small watershed measuring 234 hectares (2.34 sq.km), underlain by hard rock at a cost of 2.12 lakh using locally available clay at Gaurelli village, Yacharam mandal, Ranga Reddy District. The impact assessment study indicates that the construction of sub-surface dam enabled to conserve groundwater additionally to the tune of 10.32 ham and 31.5 ham during 1997 and 1998 respectively on the upstream side. Also there was considerable reduction in the fluoride concentration in the groundwater.