Comprehensive Hazard Assessment of Tropical Cyclone-Induced Wind, Rainfall, and Storm Surge: A Case Study of Zhejiang Province, China

Abstract Tropical cyclones pose a significant threat to coastal regions through hazard-inducing factors such as wind, rainfall, and storm surge, whose interactions often lead to amplified impacts. Existing studies often fail to capture the complex dependence among these factors. This study focused on the coastal counties of Zhejiang Province, utilizing numerical simulation data of tropical cyclone-induced winds, rainfall, and storm surges from 1979 to 2022. A joint probability model based on the C-vine copula function was developed to characterize the synergistic mechanisms among these factors, and to analyze return periods and failure probabilities of engineering structures under different hazard scenarios. Furthermore, a comprehensive hazard index was introduced to assess the hazard of tropical cyclone events. The main findings are as follows: (1) The simulated data agreed well with observations, with root mean square errors below 4 m/s for wind and 0.2 m for storm surge, and correlation coefficients all above 0.75. (2) Neglecting multiple factors and their dependence introduced bias in the return period and failure probability estimates. For example, when the exceedance probability for each single factor was 0.05, the mean return period for the three factors under the independence assumption (1.760 years) was 35% shorter than that considering dependence (2.698 years). (3) The comprehensive tropical cyclone hazard in the coastal counties of Zhejiang exhibited a distinct spatial pattern, with higher values in the south and lower values in the north. This study provides a scientific basis for disaster risk management and the design of tropical cyclone protection infrastructure in coastal areas.