Estimation of breaking wave region based on coupled wave and storm surge simulations of historical typhoons: A case study of Hangzhou Bay

Abstract

Breaking waves pose a serious threat to offshore structures. Estimating the breaking wave region is hence important for structural design and construction. This paper developed a numerical approach for estimating the breaking wave region based on the coupled wave and storm surge simulations of typhoons. The SWAN + ADCIRC coupling model was employed to hindcast the wave height, wave period, and storm surge under historical typhoons. The values of two breaking prediction variables at different mean return periods (MRPs) were calculated by probability models. The breaking wave region can then be estimated by either a univariate or bivariate probability model of the breaking prediction variables. The developed approach was illustrated using Hangzhou Bay as a case study. Hindcast simulations of 40 typhoons in the past 25 years were conducted. The effects of breaking criteria, probability model, and breaking threshold on the breaking wave region were investigated and discussed as a function of MRP. The main findings include that 1) the waves on the north shore of Hangzhou Bay break more easily; 2) the distribution and area of the estimated breaking wave region depend on the selection of breaking criteria and thresholds; and 3) neglecting the correlation between variables results in an underestimation of breaking wave hazards. This study provides engineers with an efficient tool to estimate the breaking wave hazards for projects located in tropical cyclone-prone sea areas.