基于 Copula 函数的沿海城市雨潮复合灾害风险研究

Coastal cities are extremely vulnerable to compound flood disasters caused by extreme rainfall and high storm surge. In order to accurately assess the risk of compound flood disasters in coastal cities,it is essential to esti⁃ mate the dependence between extreme rainfall and storm surge. In this study,we use the maximum daily accumulat⁃ ed rainfall in Shanghai from 1979 to 2014（36 years）and the maximum storm surge at Wusongkou station on the day of the maximum precipitation and 3 days after the maximum rainfall. The marginal distribution function is opti⁃ mized by KS,AIC and BIC testing methods. The function quantitatively evaluates the compound flood risk of the combination of rainfall and storm surge under different joint return period in Shanghai. The results show that the 36⁃year maximum daily rainfall and the corresponding maximum storm surge at Wusongkou are both suitable for fit⁃ ting with the GEV distribution；the Frank Copula function has the best fitting for the joint distribution of rain⁃ fall⁃storm surge encounter in Shanghai；the joint probability of rainfall and storm surge is 4.12,7.51,14.21,34.27,67.72 times of the co⁃occurrence probability under different joint return period；Under the 100⁃year joint re⁃ turn period,the rainfall and storm surge are 276 mm and 3.5 m,which shows that coastal regions should prevent strong occurrences in 100 years. Beside this,an additional design and construction of a flood wall of at least 3.5m shall be made in consideration of the astronomical tide. This study presents that the Copula function can more accu⁃ rately calculate the design rainfall and storm surge under different joint return period,which provides the possibili⁃ ty for optimizing the design standards of flood control projects and designing scientific compound flood disaster sce⁃ narios.