Measurement of submarine groundwater discharge using diverse methods in Coleroon Estuary, Tamil Nadu, India

Abstract

Submarine groundwater discharge (SGD) is described as submarine inflow of fresh and brackish groundwater from land into the sea. The release of sewages from point and non-point source pollutants from industries, agricultural and domestic activities gets discharged through groundwater to ocean creating natural disparity like decreasing flora fauna and phytoplankton blooms. Hence, to quantify fluxes of SGD in coastal regions is important. Quantification of SGD was attempted in Coleroon estuary, India, using three dissimilar methods like water budget, Darcy law and manual seepage meter. Three seepage meters were installed at two prominent litho units (alluvium and fluvio marine) at a distance of (0–14.7 km) away from Bay of Bengal. The water budget and Darcy law-quantified submarine seepage at a rate of 6.9 × 10⁶ and 3.2 × 10³ to 308.3 × 10³ m³ year⁻¹, respectively, and the seepage meter quantified seepage rate of 0.7024 m h⁻¹ at an average. Larger seepage variations were isolated from three different techniques and the seepage rates were found to be influenced by hydrogeological characteristics of the litho units and distance from the coast.