GROUND WATER RECHARGE IN WAGARWADI WATERSHED THROUGH RECHARGE PROCESS AND GROUND WATER FLOW MODELS

The Wagarwadi watershed covering 324 ha in Parbhani District, Maharashtra, India is in the semi tropics and receives a mean annual rainfall of 900 mm. The recharge of the aquifer, due mainly to rainfall during the monsoon season, was modeled using daily rainfall and pan evaporation data for 11 years. The recharge water balance accounts for interception loss, surface runoff, evapotranspiration and soil moisture status. Aquifer parameters viz., transmissivity and specific yield were estimated through pump tests. The aquifer system was modeled as a single weathered leaky aquifer using integrated finite technique on a nested square grid. Steady state conditions were simulated assuming an equilibrium condition during May 1997 which was considered as the initial water level. During steady state calibration, the transmissivity values were modified in some pockets to match the computed and observed water level contours. Irrigation return seepage was found to be contributing significantly to the groundwater regime. The monthly recharge estimates of the model were fed as input to the aquifer model in transient condition. The aquifer model was refined and the monthly recharge estimates were found to be adequate for simulation of water table behaviour. The monthly recharge estimates are very helpful in determining the magnitude of time - variant input due to rainfall to the aquifer system. The soil and water conservation practices in the watershed have increased the soil moisture status and recharge of water in the wells. Ultimately there was an increase in the area under double cropping along with assured irrigation for orchards.