Wave height variability and extreme wave height estimation at remote islands of Lakshadweep for planning of infrastructure, Arabian Sea

Lakshadweep islands are coral atolls islands which are characterized by complex wave transformation patterns due to their unique geomorphological features, such as reef flats, lagoons, and steep fore-reef slopes. Coastal erosion and high wave events in Lakshadweep islands located in Arabian Sea have become more common in recent days, especially during every monsoon and during cyclonic storms. Lakshadweep islands, with a tiny land area, the erosion of even a small portion of the land can be a significant loss to habitat and livelihood. This research aims to investigate the spatial variability of wave climate around the highly populated Androth island of Lakshadweep, which is oriented in east west direction. The numerical model was employed to simulate the long-term nearshore wave climate for the period of 40 years from 1981 to 2020, which examines the interannual variability and seasonal variability of wave climate at various zones of the Androth island. The study also examines the extreme wave climate around the Androth island using long-term hindcast wave data for various return periods. The analysis reveals that the western zone of the Androth island experience high intensity of waves due to high steepness in bathymetry and configuration of island. The western zone of the Androth island is characterized by annual mean significant wave height in the range of 1.2 m to 1.5 m and with high coefficient of variation values for significant wave height. During 1981 to 2020, a statistically significant positive trend of 0.24 cm/year is observed in the annual mean significant wave height in the southern zone of Androth island. The extreme value analysis of wave height reveals that the 100-year return period of significant wave height ranges between 3.32 m and 4.92 m around Androth island. The combined analysis of wave variability and extreme values supports better site selection, optimal design and resilient planning of coastal and offshore infrastructure.