Study on torrential rain comprehensive disaster-causing index and its threshold based on Dominance Analysis Method: A case of insurance industry in Zhangjiajie City

First, based on the precipitation data and torrential rain disaster data in Zhangjiajie City of Hunan Province from 2016 to 2020, taking the claim cases of the property and cargo insurance (hereinafter referred to as "property and cargo insurance") from Hunan Branch of the People's Insurance Company of China as the research sample, the Dominance Analysis Method was used to determine the influence weights of disaster-causing factors to establish a comprehensive disaster-causing index (I) model of torrential rain. Second, an exponential function is used to fit the relationship between the number of town or street which filed claims of property and cargo insurance and I, then to determine the threshold of I corresponding to different accident levels. Finally, the claim case caused by torrential rain disaster in Zhangjiajie in the flood season of 2021 were selected to verify the I and its threshold. The results show that the number of property and cargo insurance accidents caused by torrential rain in Zhangjiajie is generally low in east and west but high in middle areas. Among the disaster-causing factors, the weight of the 96-hour accumulated precipitation on the scope of accident is the largest, reaching 28.6%. The simulated grades of the scope of accident, the amount of claim and the number of accidents of property and cargo insurance have a high correlation with the grades of actual disasters, and all passed the test at the 0.01 significance level. The threshold test results show that the consistency rate or accuracy between the predicted level and the actual level of torrential rain disaster-causing cases is 71.4%, in which the predicted values of accuracy for the mild, moderate and severe disaster levels are 70%, 70% and 100%, respectively. Therefore, the threshold of I established in this study can be used for the industrial meteorological services related to the property and cargo insurance in Zhangjiajie.