This paper presents applied research on fuzzy logic modeling to forecast the distribution of salinity in the coastal region of southern Tamil Nadu, India. Geoelectrical resistivity data has been used in this research, apart from nominal approach of salinity forecasting using geochemical data analysis. The data collected using vertical electrical sounding (VES) method was fed as an input for fuzzy inverting algorithm to evaluate true resistivity and thickness of subsurface layers. Inverted resistivity values have been subjected to fuzzy rule-based approach for salinity forecasting. Classifications have been made on the basis of linguistic variables with five linguistic terms of resistivity range using a triangular membership function of fuzzy logic. The purpose is to find the saltwater intrusion in the coastal region of Tuticorin district, Tamil Nadu, India. This research work reveals that fuzzy logic would be the effective tool for solving complex problems as well as enhancement in integrating multiple features necessary for the study. The results overlain in the surrounding regions which were mapped the threatening zones; hence, to mark pre-awareness in the regions, more rainwater harvesting system and avoidance of human anthropogenic activities need to be implemented.