Numerical Simulation and Prediction of Groundwater Flow in a Coastal Aquifer of Southern India

Abstract

Chennai is one of the most water-stressed cities in south India due to rapid industrialization and urbanization. The well fields located in north and south of the Chennai city meet part of the city’s water requirement. The south Chennai aquifer is surrounded by saline surface water on all sides. Since 1990, the influence of seawater in to this freshwater aquifer has been reported as an issue for consideration and mitigation measures. Therefore, in the present study an attempt is made to comprehend the status of aquifer with present level of pumping/recharge and to predict the behavior with different hydrologic stresses. Numerical modeling was carried out by finite element approach using FEFLOW software. The model has been developed with three subsurface layers and simulation was processed from January 1998 to December 2020. The groundwater usage had varied from 11.3 MLD to 17.2 MLD during the period of study. If the recharge and discharge continue in a similar pattern, the maximum level of freshwater decline will be 0.32 m at the end of 2020. Hence, prediction of behavior of this aquifer for increased discharge and decreased recharge scenario has been carried out. It is found that with an increase of discharge, there is a sharp change in interface of seawater and freshwater. This model can be used as a tool to understand the aquifer regionally and to plan proper groundwater management measures.