Accurate estimation of groundwater recharge is extremely important for proper management of groundwater system especially in semi-arid regions. Many different approaches exist for estimating recharge. This study deals with groundwater modeling for assessing the groundwater balance and estimating the recharge in the Gundal sub-basin, which is located in a semi-arid portion of the Kabini river basin. A two-dimensional fully distributed groundwater model on the concept of predominantly lateral flow conceptualized as an unconfined aquifer has been used in this study. The modeling is supported through remote sensed data and GIS. The different modeling approaches used here gave consistent set of specific yield, transmissivity and rainfall recharge factor with the assumption of zero flow condition specified along the basin boundary. However, these parameters are found to be lower than what is usually known to occur in this geo-climatic context. The results of groundwater modeling, further supported through the groundwater chemistry analyses, show the impact of pumping resulting in regional groundwater flows influencing the hydrogeological regime in the recharge zone. The study also indicates that water levels in the excessive groundwater depletion zones in the Gundulpet area are sustained at the present level due to the inflows from the adjacent Nugu river basin.
Groundwater, numerical modeling, recharge, water balance, gneissic aquifer, semi-arid zone