Projected changes in extreme waves and coastal hazards along the North Indian Ocean Coast utilizing high-resolution CMIP6 wave ensemble

Ocean surface waves are key drivers for coastal dynamics, influencing shoreline changes, sediment transport, and the structural stability of coastal infrastructures. In this study, we investigated the projected changes in wave climate with a particular focus on extreme waves and coastal hazards along the North Indian Ocean (NIO) coastline using an eight-member ensemble of CMIP6-forced WAVEWATCH III simulations obtained at a high coastal resolution of approximately 6.8 km × 9.5 km. Historical simulations (1985-2014) were evaluated against Copernicus reanalysis for future projections covering the mid-century (2041-2070) and the end-of-century period (2071-2100) under the SSP1-2.6 and SSP5-8.5 emission scenarios. Seasonal maximum significant wave heights were found to increase by 0.5-0.8 m in regions of the Bay of Bengal (BoB) and along the west coast of India. Extreme value analysis based on the Peaks Over Threshold (POT) approach fitted to a Generalized Pareto Distribution (GPD) indicates that 50-year return levels of significant wave height increased by approximately 0.60 m along the Arabian Sea coast, representing a 7-12% amplification in extreme events. During the winter and post-monsoon seasons, the coastal hazards hotspot distribution appears in the western Arabian Sea, Gujarat coast, and along the Odisha-West Bengal coastline under the high-emission scenario.