ASSESSMENT OF THE IMPACT OF SEA LEVEL RISE ON SHORELINE DYNAMICS OF SANDY COAST ON THE EAST COAST OF INDIA

Abstract

Coastal zones are among the most highly developed regions in the world, and play a crucial role economically and environmentally. Sea-level rise and changes in wave dynamics are expected to cause shoreline retreat along open sandy coasts. This study evaluates the potential shoreline response to sea-level rise (SLR) through numerical wave modeling and an empirical shoreline recession model. The wave conditions were simulated using the MIKE 21 Spectral Wave (SW) module for the period 1970–2020, and the model outputs were validated against observed data from two locations, Chennai and Puducherry. In the study region, the average H_s, T_m, and D_m were varying 0.96 m, 6.24 s, and 112° (E-SE), respectively. The Depth of Closure (DoC) was estimated using the Hallermeier (1978) method based on mean wave conditions. Future shoreline recession was assessed using the Bruun rule, considering sea-level rise projections for 2100 under the IPCC SSP2-4.5 and SSP5-8.5 scenarios. Beach profiles were generated by integrating measured bathymetric with topographic data. Based on the modeled wave data, the Depth of Closure (DoC) was estimated to be approximately 5 m. The results indicate that, the shoreline retreat was observed along the sandy beach on the Chennai coast, approximately 17 m and 26 m under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. The present study provides a first-order assessment of potential shoreline retreat along the open sandy coast. This integrated framework provides valuable insights for coastal managers and policymakers to support the development of adaptive strategies for climate-resilient shoreline management.