Three Dimensional Finite Element Modelling of Groundwater Flow for Sustainable Pumping from North of Chennai Coastal Aquifer, Tamil Nadu, India

Groundwater from the coastal aquifers north of Chennai is being pumped since 1981 to meet the increasing demand. Huge groundwater extracting in the coastal aquifers groundwater causes lowering of groundwater table which led to seawater intrusion. The objective of this study is to assess the behavior of this aquifer to seawater intrusion under different hydrological stresses by groundwater modelling. Intensive field visits were carried out and 45 monitoring wells were identified. Groundwater level has been measuring once in two months from the year 2011. Aquifer properties such as transmissivity and specific yield were obtained from other agencies. Finite element groundwater flow modeling was carried out using FEFLOW with the period of March 1988 groundwater head as an initial condition. Boundary conditions are assigned based on the groundwater flow across the study area. Steady state calibration was done to adjust the hydraulic conductivity and specific yield values. Time varying inputs such as abstraction and recharge were used and calibration of the model was made during the period from 1988 to 2002. Validation of the model was made for comparing the simulated and observed groundwater levels from the year 2003 to 2012. Simulated groundwater level was in near agreement with observed groundwater level. The model was later used to assess the variation in groundwater levels with changes in recharge and pumping rates. This study was useful for understanding the response of subsurface aquifer system under different hydrological stresses and sustainable utilization of groundwater.