Variabilities in the estimate of 100-year return period wave height in the Indian shelf seas

Exploring the variability in design wave heights through extreme value analysis is crucial for understanding extreme oceanographic conditions and is paramount for the safe design and operation of offshore structures. This research delves into a comprehensive analysis of wave height variability in the Indian shelf seas, focusing on wave heights for a 100-year return period at 30 locations using 42 years of reanalysis data. The study employs the Generalized Extreme Value distribution and the Generalized Pareto Distribution (GPD), utilizing the annual maxima approach with three methods: maximum likelihood, probability-weighted moments, and moments of probability scale. The GPD Peaks Over Threshold (POT) approach is explored with thresholds estimated using various (91 to 99) percentiles, alongside a graphical approach utilizing threshold determination through mean residual life (MRL) plots. Results indicate that the GPD POT approach, particularly when employing thresholds derived from MRL plots, outperforms other methods. Thresholds obtained by MRL method closely align with the thresholds obtained through the 99 percentile for all locations in the Arabian Sea. This investigation not only enhances our understanding of the dynamic wave processes in the Indian shelf seas but also underscores the efficacy of specific statistical distributions and approaches in the evaluation of design wave heights.