Temporal and spatial distribution of compound flood potential in China’s coastal areas

Abstract

Heavy rainfall, coupled with storm surge and river flooding, are typical compound flood driving elements which cause much heavier losses than that of single driving element. To address this issue, we propose a framework for assessing compound flood potential. The framework includes three aspects: 1) Defining and sampling compound events under different scenarios. 2) Based on Kendall correlation, joint return period and Copula model to quantify compound flood potential. 3) Explore the impact of typhoons on compound events and generate a spatiotemporal distribution map of typhoon compound events. We explore the applicability of this framework by taking China's coastal areas as an example. The results show that different definitions of compound events and different sampling methods can affect the quantification results of compound flood potential. Overall, the potential of compound flood in the southern coastal provinces is higher than that in northern provinces, and the potential of compound flood is still increasing in some areas with high potential. At the same time, it is found that typhoon is the most significant conditions leading to compound events, and its intensity and path also affect the generation and distribution of compound events. The rainfall associated with tropical cyclones is the main contributor to the disaster loss of compound events. The framework is based on global data sets for calculation and analysis, which can provide reference for compound flood risk assessment in other areas lacking data.