Modelling Groundwater Flow for Vadachitur Watershed in Parambikulam Aliyar Palar Basin

A three-dimensional finite-difference groundwater flow model was implemented to investigate the variety of hydrogeological conditions and to simulate the behaviour of the flow system under different stresses in the aquifer system of Vadachitur watershed. The modelling package VISUAL MODFLOW version 4.1, employed in the Groundwater Modelling System (GMS) for this purpose. The Vadachitur watershed is located in the Parambikulam-Aliyar-Palar basin of Tamil Nadu. The upper formation consists of thin sandy loam and the lower one is coarse silts with combination of sand and gravels. The aquifer system is underlain by crystalline rocks of Archean age. The two-layer model was calibrated with two steps: i) a steady state calibration, using observed ground water levels of the year 2011. Estimation of the hydraulic conductivity, specific yield and specific storage were assigned for each layer of themodel based on the hydrological formation and pumping tests. The simulation results show that the fluctuations of hydraulic heads are dependent on seasonal variation in recharge from natural infiltration of precipitation and irrigation. Also, the model can simulate the positive fluctuations of the hydraulic heads in Vadachitur watershed aquifer, with different responses of the hydrogeological system; ii) Different scenarios were considered to predict aquifer system response under different conditions.