Geophysical and geochemical prospecting for submarine groundwater discharge in a karst leaky aquifer from Valliyur Hills to Uvari Beach

Coastal freshwater aquifer characteristic study is essential for drinking water and domestic purpose. SGD of groundwater flux study was carried out using geophysical methods such as Azimuthal square array resistivity, 2D electrical resistivity imaging (ERI), magneto-telluric and geochemical analysis of water samples. In the square array method, the resistivity of fractured/ faulted zone with leaky aquifer of SGD is identified using resistivity variations. The 2D ERI techniques apparent resistivity values changes and pseudo-section colour difference are used for SGD flow path. Magneto-telluric method is a tool for SGD flow in the subsurface karst topography with differentiating flow of depth. The grain size analysis of beach sediments as fine sand is encountered in the statistical analysis of grain sorting. The deeper aquifer location is identified using square array and magneto-telluric method layer by layer. The magneto-telluric resistivity profiles observation of aquifer thickness, soil, and rock hydraulic conductivity, the gradient of flow using Darcy’s law was used to estimate the flux of the Uvari beach SGD flow rate. The geochemical phases of freshwater samples U2, U3, U4 U6, U7, U8, U9 mixing of HCO3 and seawater intrusion in U1, U5 in Mix SO4 concentration is found in the study.