Simulation of Saltwater Intrusion in a Coastal Aquifer in Karnataka, India

A grid based variable density numerical model, SEAWAT-2000 is used to conceptually simulate groundwater flow and transport for a coastal stretch in Karnataka state, India. SEAWAT is a coupled version of MODFLOW and MT3DMS designed to simulate three-dimensional, variable density groundwater flow and multi-species transport. The variable density flow process uses the familiar and well established MODFLOW methodology to solve the variable density groundwater flow equation. The aquifer considered for the present study is bounded by Arabian sea on the west, the ridge line along the east andShambhaviand Pavanjerivers along the northern and southern sides respectively. The study has its focus on managing the available data in the most efficient manner to develop a reliable and sophisticated simulation model. The aquifer parameters are estimated by calibrating the model for two year period with daily time step. The aquifer can be categorized as unconfined having good groundwater potential with aquifer transmissivity and specific yield ranging from 10 to 810 m2/day and 0.0008 to 0.0122 respectively. The model evaluation in terms of the accuracy is carried out bycomparingwith the measured data on seasonal basis.From this, the model is found to be scientifically sound for further management applications. The model so developed can be applied in predicting the saltwater intrusion in coastal aquifers for various developmental and climate change scenarios like sea level rise.