A method for constructing loss functions based on flood disaster events

The construction of flood disaster loss functions is of great significance for understanding the development law of flood disaster loss and improving the timeliness of loss assessment. A method for constructing loss functions based on urban flood disaster events is proposed, which is coupled with dynamic simulation of spatial distribution of flood disaster factors, spatial processing of socio-economic data, calculation of direct and indirect disaster losses, and curve fitting. A case study was carried out in Shanghai to construct flood disaster loss-time functions, and the adjustment strategy of function parameters was established. The results show that under the rainfall scenario of Chicago rain type, the development process of direct economic losses from flood disasters shows an S-shaped curve and Weibull distribution function can be used as the loss function. The development process of daily loss from production reduction and shutdown shows an L-shaped curve and hyperbolic decline curve function can be used as the loss function. The development process of daily industry-related loss shows an inverted U-shaped curve and Hoerl distribution function can be used as the loss function. The cumulative industry-related loss is about 1.77 times of the loss of production reduction or shutdown, and the indirect economic loss is about 1.29 times of the direct economic loss. The parameters of the loss function and the probability of disaster occurrence exhibit a nonlinear monotone increasing or decreasing relationship, the relative error of flood loss assessment based on fitting parameters is less than 5%. The method in this study has been proven to have high simulation accuracy, providing a new way to understand the development law of flood disaster loss and improve the timeliness of flood disaster loss assessment.