Saline water intrusion in the coastal areas is nowadays turning into a major issue, and the development of saline water is going into coastal aquifers. The examination is taken up for Nagapattinam coastal stretch, and the areal extent of the study area is around 534 km². In the framework of the EU-India INCO-DEV COASTIN project aiming at assessing aquifer vulnerability in coastal aquifers, the first development of the GALDIT model was carried out. The most significant variables controlling the intrusion of seawater were perceived as accompanying: Groundwater (aquifer type; unconfined, confined, and leaky); hydraulic conductivity of the aquifers; depth to groundwater levels above the sea; distance to the shore (inland perpendicular to shoreline reach); effect on the area’s current status of sea water intrusion; and thickness of aquifer have been mapped. These variables, in blend, are determined to incorporate the fundamental parameters expected to survey the general seawater intrusion capability of each hydrogeologic setting. GALDIT factors represent measurable parameters for which information is commonly accessible from an assortment of sources without detailed examination. A numerical ranking system to assess seawater intrusion potential in hydrogeologic settings has been conceived utilizing GALDIT model. The framework contains three significant parts: loads and extending from 1 to 4 (1: least significant to 4: most significant), and a rating value between 1 and 10 relies on the local conditions. Each GALDIT factor was assessed for the other to decide the overall significance of each factor. The outcome demonstrates that 58.62 km² regions are profoundly helpless against saline water interruption. Around 174.86 sq.km areas found vulnerable, moderately areas are found 192.07 sq.km and 103.15 sq.km areas falls under low vulnerable for saline water intrusion.