Long-term Shoreline Dynamics of South Kerala Coast using Satellite images

The shoreline experiences significant changes due to human activities and natural processes, resulting in erosion and accretion. Studying the morphology of shorelines is crucial for identifying the causes and impacts of coastal processes along the coast, which helps protect the ecosystem and facilitate future development. This study comprehensively analyses shoreline changes along the Kerala coast from 1973 to 2024, revealing substantial shifts due to frequent cyclones and other natural events. Key findings include significant erosion at Shangumugam, Valliyathura, Punthura, and Edapadu beaches and notable accretion at Thumba, Kochuveli, Vizhinjam, Adimalathura, Pullavila, Karumkulam, and Poovar. Trend analysis from 2000 to 2024, using high-resolution satellite images, identified consistent erosion patterns, particularly after Cyclone Ockhi in 2017, which caused significant, unrecovered erosion along the Vizhinjam coastline. It is observed that the frequency of cyclonic activity has increased in recent times. Validation of shoreline data derived from satellite images of varying resolutions (PAN (2.5m), LISS 4 (5m), MSI (10m)) against field data collected using DGPS demonstrated that higher spatial resolution results in more accurate shoreline extraction, with errors decreasing from 3.3m (10m vs. 1m) to 0.3m (2.5m vs. 1m). This highlights the importance of high-resolution satellite imagery in monitoring and managing shoreline changes. The study accentuates Kerala's increasing vulnerability to natural disasters and the necessity of advanced monitoring techniques for effective coastal management.