Study of sampling methods for assessment of extreme significant wave heights in the South China Sea

Abstract

Adequate knowledge of extreme wave events is crucial for the coastal and offshore engineering community. In this study, assessment of extreme significant wave heights is performed in the South China Sea (SCS). Significant wave heights from a 40-year (1975–2014) hindcast of tropical cyclone waves are adopted as the initial database. The annual maxima (AM) method with the Gumbel model, a conventional method, is used to assess extreme significant wave heights, which fits the annual maximal significant wave height for extrapolation. The peak over threshold (POT) method with the generalized Pareto distribution (GPD) model is applied to determine return significant wave heights with certain return periods by fitting the peak excesses over a sufficiently large value (the threshold). To select the suitable threshold for the POT method, the sensitivity of the return significant wave height to the threshold is analysed. Based on the sampling theory and the characteristic of hindcasted significant wave heights of tropical cyclone waves, applicability of two sampling methods in the SCS is investigated.