Geoelectrical surveys provide an effective way to image the subsurface and the groundwater zone without a large number of observation wells. Resistivity sounding generally identifies the subsurface formations such as aquifer zone as well as the formations saturated with saline or contaminated water. The integration technique in groundwater by geochemical analysis and geophysical survey helps in identification of salt water intrusion and contamination by industrial effluents. A resistivity survey was conducted in a coastal aquifer lying in the lower part of the Gadilam River basin, Tamilnadu, India. When the resistivity interpretation becomes confusing, chemical analysis data prove to be a powerful method of identification of subsurface formations, groundwater zones, the groundwater salinity or anthropogenic contamination, and their causes. The interpretation of data reveals that contaminated water near the industrial effluent was identified at shallow depths at Karaikadu suggested by higher ionic concentrations. The saline water intrusion is noted in the deeper aquifer with low resistivity values. Good potential water was noted in Ramapuram and Naduveerapattu, which are located away from the coast.