An Account of Submarine Groundwater Discharge from the SW Indian Coastal Zone

Two probable zones of submarine groundwater discharge (SGD) from the SW coastal zone of India are reported. They lie between the prominent coastal promontories, namely Kovalam in the Thiruvananthapuram district of Kerala state and Muttam in the Kanyakumari district of Tamil Nadu state. The purpose of characterizing such groundwater leakage zones, in general, is (i) to assess the optimum exploitation levels of coastal fresh groundwater; (ii) to locate feasible waste disposal sites in the coastal zone, and (iii) to estimate seaward pollution transport levels. Indirect indications on the basis of satellite digital data analysis, systematic fieldwork, physicochemical water quality checks, and also resistivity surveys have been utilized to understand the nature of groundwater movement in the coastal aquifers. Geomorphological settings, temporal water quality variations, and subsequent determination of hydrochemical facies have provided evidence for explaining the phenomenon of SGD. In particular, the indications of streaming potential, inferred interface geometry patterns, and truncated lithological layering point to the presence of groundwater discharge across the recognized sections.