Satellite and Geographic Information System-Incorporated Multi-Platform Monitoring of Coastal Erosion on the Northwestern Coast of Sri Lanka

Coastal erosion is the degradation of shorelines caused by natural factors such as sea level rise, currents, and wave action, as well as human activities like construction, deforestation, and fisheries. This process leads to the loss of land and sediments. In Sri Lanka, this phenomenon has impacted 15 tourist attractions in Kalpitiya, altering coastal landforms, including beaches, cliffs, dunes, and barrier islands. Over time, a 50-meter stretch of beach has been destroyed, resulting in the loss of valuable coastal habitats and infrastructure. This study investigated shoreline changes and calculated erosional and depositional rates using Geographic Information Systems (GIS) and remote sensing techniques. The region of interest (ROI) covered the coastal area from Mannar to Puttalam on the northwest coast of Sri Lanka. To analyze shoreline changes, vector data were processed using the Digital Shoreline Analysis System (DSAS V5_0) integrated with ArcGIS 10.5. Secondary data sources included topographic maps, digitized shorelines, and satellite maps obtained from the Survey Department and the United States Geological Survey (USGS) website. Coastal slope and contour lines were created to understand coastal geomorphology and its characteristics. Moreover, the Topographic Wetness Index (TWI) and Normalized Difference Vegetation Index (NDVI) were examined for supportive analysis. Weighted linear regression rate analysis revealed that the Kalpitiya vulnerability region experienced approximately 69% erosion and 30% accretion. The Erosion Potential Rate (EPR) parameter was used to calculate erosional and depositional rates, showing a maximum erosional rate of 13.48 m/year and a maximum depositional rate of 25.36 m/year.