Perspectives on compound flooding in Chinese estuary regions

This study proposed a copula-based framework to quantify flood hazards in coastal regions that are exposed to the combination of storm surge and pluvial flooding. This can provide insights into adaptation strategies that account for coastal and pluvial flooding protection infrastructure. We observed that in southern China the highest number of extreme surge events occur during typhoon seasons, while in the northern part of the country the majority of the surge peaks occur during the non-typhoon season. This is expected because typhoons largely affect the southern region.

The main results from the study are that: 

1. There is a positive and significant correlation between surge peaks and rainfall in 10 of the 26 catchments investigated; 
2. The probability of rainfall conditional on a specific surge event can provide valuable information for the design of flood protection systems in estuary regions; 
3. In southern China (Hainan Island), extreme rainfall events during the typhoon season are generally more intense compared to most annual maxima events. The framework developed in this study can be applied to other coastal cities or regions in East and Southeast Asia and around the world.