A coastal groundwater management model with Indian case study

Abstract

The complexity of the hydrogeological setup in coastal areas calls for the adoption of scientific groundwater management techniques. Excessive withdrawal of groundwater in coastal zones will lead to depression of the water table, with associated hazards such as putting the well out of use, rendering abstraction uneconomic with increased lift. A sustained regional groundwater drawdown below sea level runs the risk of saline water intrusion, even for confined coastal aquifers. Uncontrolled groundwater development may lead to reversal of the freshwater gradient, thereby resulting in saline water ingress into coastal aquifers. There are, however, several established methodologies to control and minimise the problems associated with groundwater extraction followed by saline water intrusion. This study developed a convenient and easily implementable analytical model for coastal groundwater management aimed at the control of saltwater intrusion. The technique includes withdrawal of coastal freshwater by means of qanat-well structures associated with artificial recharge through rainwater harvesting aided by percolation ponds and recharge wells. The proposed methodology is suitable specifically for not highly urbanised coastal areas with significant annual precipitation, good hydraulic conductivity of the aquifer and a low depth of fresh groundwater. As a case study, the model is applied to a coastal zone of the Purba Medinipur district of West Bengal, India. Adequate quantifications of the efficiency of the methodology are incorporated and relevant conclusions are drawn.