Modelling the Spatial Distribution and Future Trends of Seawater Intrusion due to Aquaculture Activities in Coastal Aquifers of Nizampatnam, Andhra Pradesh

Abstract

Coastal aquifers suffer from saltwater intrusion due to several natural and anthropogenic activities and they pose a severe problem in many coastal regions of India. Anthropogenic activities like saltwater aquaculture activities and salt pans are one of the major causes for saltwater intrusion into freshwater aquifers in coastal regions. Along with these activities, over-exploitation of fresh groundwater for domestic and agriculture purpose also leads to infiltration of saltwater into shallow freshwater aquifers. To address this effect, it is necessary to understand the spatial distribution and extent of the saltwater intrusion in coastal areas. In the present study, SEAWAT model is used to delineate the saltwater intrusion effect and predict the extent of saltwater intrusion resulting from anthropogenic activities in the Nizampatnam coastal area, Andhra Pradesh. The simulation was carried out for the period 2016 to 2018 revealing a change in the extent of the saltwater intrusion up to 2 km into the inland areas from the coast as well as in the vicinity of fishponds. Based on the hydrological conditions observed during the study period and leveraging the calibrated model, saltwater intrusion prediction was carried out for the next two decades. The results show that anthropogenic activities will lead to saltwater intrusion into freshwater aquifers up to 6 km into inland areas from coast at a rate of 200 m/year. Therefore, the sustainable management plans are essential for protecting the freshwater aquifers from the saltwater intrusion in the Nizampatnam coastal area.