Integrated surface water and groundwater modeling

Chennai is the 4th largest metropolitan city in India located on the Coromandel Coast off the Bay of Bengal. Water supply to the city is met from reservoirs and a large amount of groundwater is also pumped from the bore wells located in the well fields of Arani and Koratalaiyar river basin (A-K Basin) north of Chennai. Over-pumping of groundwater from the well fields to meet the demand of the fast growing city of Chennai as well as for local irrigational needs has led to significant seawater intrusion. To overcome this problem, as a measure of Managed Aquifer Recharge (MAR) several check dams have been constructed across the two rivers to increase the groundwater recharge and to reduce the outflow into the sea. The water stored in each of these dams infiltrates into the underlying aquifers and increases the groundwater level. Various researchers have questioned the efficiency of check dams in dry regions such as Chennai, where evaporation losses are substantial. A major part of the EU funded project Saph Pani ("Enhancement of natural water systems and treatment methods for safe and sustainable water supply in India") involves optimizing MAR structures in the A-K basin. Based on this project the present study aims at analyzing the effects of these and planned check dams to counteract the growing conflicts between different stakeholders in the region. These analyses were performed by setting up a 3D unsaturated groundwater flow model fo