Groundwater modeling for assessing the recharge potential and water table behaviour under varying levels of pumping and recharge

Increased abstraction to meet the food demands of the burgeoning population has raised the concerns for groundwater sustainability in several parts of India. In order to develop an optimum management plan for such areas, impact of various management alternatives on water tables needs to be assessed. This study investigates the impact of different rates of groundwater withdrawal and artificial recharge on water tables in IARI farm located in alluvial tracts of Northern India. A three dimensional finite difference model MODFLOW was used to simulate the aquifer system of the study area. The model was calibrated and validated using observed data for the period 2007 to 2010. The results of calibration and validation showed agreement between observed and predicted water table elevation. The coefficient of determination (R) ranged between 0.80 to 0.91 for calibration and 0.81 to 0.94 for validation. The validated model was used to simulate the water table behaviour for the period of 2012 to 2018 under eight management scenarios. The modeling results showed that the prevailing pumping rate, groundwater level would go down at an average rate of 0.64 m yr. If the pumping increases by 20%, the water table will decline at 0.91 m yr. Recharging 60% of available surface runoff would reduce the rate of groundwater decline to 0.25 m yr highlighting the fact that extensive recharging of groundwater is still not sufficient to check the declining water levels and there is need for demand management. The simulation results also showed that at prevailing pumping and recharge levels, the sustainability of groundwater resources cannot be ensured unless water availability at the IARI farms is increased.