Extreme wave and storm surge characteristics in the southeastern coastal and offshore regions of China.

A numerical model is established based on the FVCOM-SWAVE wave-current coupling model to investigate the typhoon-induced wave and storm surge level in the southeastern coastal and offshore regions of China. A hindcast of 192 typhoons from 1979 to 2023 is conducted, providing insights into the distribution of significant wave height and storm surge level. The disaster zone maps are derived from the annual extreme significant wave height and storm surge level. The results show that the maximum significant wave height for the 500-year return period is observed in the southeastern region of Taiwan. The extreme wave generally decreases northward and toward the shore, and the wave contours are almost parallel to the coastlines. Extreme storm surges are observed in the nearshore regions, especially in the Qiantang River estuary, Hangzhou Bay and Pearl River estuary. As water depth decreases, the storm surge level gradually increases shoreward. The Grade I storm surge hazard zone is predominately observed in the coastal areas near the Qiantang River Estuary, Hangzhou Bay and Pearl River Estuary.