Delineation of Groundwater Potential areas - a Case study from Tirunelveli District, TamilNadu, India

An electrical resisitivity survey consisting of vertical electrical soundings (VES) was carried out in order to delineate potential ground water locations near Tirunelveli, Tamilnadu, India. Accordingly an investigation employing VES was conducted using the Schlumberger electrode configuration. Onedimensional (1D) interpretation of the sounding data was made primarily using the curve matching method and 2D inverse modeling was carried out on the resistivity data using subsurface electrical imaging computer software packages to obtain better estimation of resistivities and thicknesses of the subsurface layers. The interpreted results were used to delineate the potential ground water aquifers. The interpretation of the VES data indicates the presence of three, four subsurface layers, the top layer is thin soil cover and the second layer is weathered or semi-weathered hard rock and the third layer is highly resistive bedrock. A fracture zone is interpreted at a depth of about 10meters and is correlated with available geological, hydrogeological and geophysical information including bore well lithology. The observed data and the interpreted data is presented here as a case study.