Paleoshoreline to Anthropocene Coast: Assessing Coastal Stability and Vulnerability in Response to Sea Level Changes

Abstract The densely populated Kozhikode coastal belt in southwest India is increasingly vulnerable to coastal hazards, exacerbated by coastal protection measures that disrupt natural dynamics. This study contrasts shoreline processes over recent geological history with current dynamics, focusing on a high-energy, micro-tidal coastline characterized by distinct paleo-shoreline features and young coastal plains from the Holocene epoch. Temporal morphological changes were assessed using various satellite products, ranging from Landsat imagery to Very High-Resolution Worldview-3 datasets. The integration of vulnerability assessments of coastal ecosystems and landform features reveals significant coastal dynamism. This study highlights critical shifts in coastal dynamics and emphasizes the urgent need for sustainable coastal management strategies to mitigate escalating vulnerabilities. Understanding these changes is essential for informed policymaking and effective climate adaptation strategies, ensuring the resilience and preservation of these vital coastal ecosystems. Analysis of shorelines from the Holocene to the present indicates a historical accretion trend until the 1960s; however, recent decades have seen a concerning reversal, resulting in coastal erosion and flooding. This paper elucidates the influences of extreme events and anthropogenic factors on coastal stability, supported by analyses of paleo-shoreline changes and contemporary disturbances linked to climate change and sea-level fluctuations. Geological and climatic events, particularly sea-level changes, are evident in paleochannels associated with the Chaliyar and Korapuzha river basins. Lithological studies from boreholes provide compelling evidence of shoreline variations, indicating that the paleo-shoreline now varies significantly from the modern shoreline across different regions. The once-accruing Holocene coast now experiences erosion along 40% of its length, with accretion rates plummeting from 100% to just 11% in recent decades, likely due to unsustainable coastal zone exploitation since the 1980s.