Geospatial assessment of shoreline dynamics in Chengalpattu district, northeastern coast of Tamil Nadu, India

Abstract

Coastal areas are among the most dynamic and sensitive environments on earth, shaped continuously by the interaction of land, sea, and atmospheric processes. The shoreline, which forms the interface between land and ocean, is particularly vulnerable to changes caused by natural phenomena such as wave action, tides, and cyclones, as well as by human interventions like coastal infrastructure development. Understanding these changes is critical for managing coastal resources and mitigating hazards. This study evaluates shoreline change along the coastal taluk of Chengalpattu district, Tamil Nadu, from 2009 to 2025 using geospatial techniques. Shorelines were extracted from Google Earth Pro and analyzed using the Digital Shoreline Analysis System (DSAS) in ArcGIS through key statistics methods such as Linear Regression Rate (LRR), Net Shoreline Movement (NSM), and End Point Rate (EPR). The result reveals that Cheyyur taluk predominantly experienced accretion, especially near the river mouth and harbour regions, with a mean LRR of 1.47 m/year. Tirukalukundram taluk exhibited a general erosion trend, with a mean LRR of -0.40 m/year, particularly in infrastructure-heavy areas such as Kalpakkam. Tiruporur taluk exhibited mixed trends with localized erosion near backwaters and development zones and a nearly neutral mean LRR of 0.06 m/year. Localized hotspots of severe erosion indicate increased susceptibility, especially in light of recent cyclonic storms, even though the district-wide average suggests mild accretion. These findings point to the need for localized, science-based coastal management strategies to enhance resilience against future coastal hazards.