Flood Hazard Zonation in a vulnerable coastal district of Tamil Nadu using Geographical Information System (GIS) and Analytic Hierarchy Process (AHP)

Tamil Nadu’s coastal districts frequently experience flooding, with Tuticorin being especially susceptible because of its low-lying terrain, estuarine systems, and concentration of industrial and subsistence activities. This study defines flood hazard zones in Tuticorin district using a multi-criteria decision-making framework based on the Analytic Hierarchy Process (AHP) and a GIS. Important variables were weighted using AHP and included in a GIS environment. These factors included rainfall, drainage density, slope, land use/cover, distance from a river, and flow length. About 85% of the district is located in high to very high flood hazard zones, primarily in coastal villages, salt pan areas, and urban communities close to estuaries. The remaining 0.47% of the district is categorised as low hazard. The results point to important hotspots that need focused interventions for infrastructure development, land-use planning, and catastrophe risk reduction. The method provides a repeatable decision-support tool for climate-resilient planning and shows how GIS-AHP Flood Hazard Zonation may be used for additional susceptible coastal districts in India outside of Tuticorin.