Computation of submarine groundwater discharge from geomorphologically different coastal catchments of SW India using numerical modeling

In this study, we investigate submarine groundwater discharge (SGD) and the influence which coastal geomorphology and geology can have on its behavior. Numerical models have been developed to estimate the magnitude of submarine groundwater discharge (SGD) from catchments with different geomorphology on the Southwest coast of India. Two coastal catchments of Thiruvananthapuram district, Kerala, India namely Varkala (184 km(2)) and Kadinamkulam (186 km(2)), have been selected to compute SGD. The results of the study confirmed that the SGD flux from the catchments differs in a great way across its multiple layers as well as in comparison to one another. The fresh SGD flux from Varkala catchment is found to be 0.1 m(3)/day/m and from Kadinamkulam catchment is 6 m(3)/m/day. In the present study, it is concluded that SGD is reflected in the heterogeneity of aquifers owing to the differences in geomorphology, land use-land cover, hydrogeology, and lithology. A numerical modeling approach that can yield reliable results with low computational cost and time is a potent method for quantifying SGD. The inferences drawn will be useful for designing aquifer recharge options and optimum pumping quantities for the region. (C) 2021 Elsevier B.V. All rights reserved.