Perspectives on Compound Flooding in Chinese Estuary Regions

Perspectives on Compound Flooding in Chinese Estuary Regions

Xu, H. (TU Delft Hydraulic Structures and Flood Risk; East China Normal University)
Ragno, E. (TU Delft Hydraulic Structures and Flood Risk)
Tan, Jinkai (Sun Yat-sen University)
Antonini, A. (TU Delft Coastal Engineering)
Bricker, J.D. (TU Delft Hydraulic Structures and Flood Risk; University of Michigan)
Jonkman, Sebastiaan N. (TU Delft Hydraulic Structures and Flood Risk)
Liu, Qing (East China Normal University)
Wang, Jun (East China Normal University)

2023

Extreme surges and rainfall represent major driving factors for compound flooding in estuary regions along the Chinese coast. The combined effect of extreme surges and rainfall (that is, compound floods) might lead to greater impacts than if the drivers occurred in isolation. Hence, understanding the frequency and severity of compound flooding is important for improving flood hazard assessment and compound flood resilience in coastal cities. In this study, we examined the dependence between extreme surges and corresponding rainfall events in 26 catchments along the Chinese coastline during typhoon and non-typhoon seasons using copula functions, to identify where the two drivers more often occur together and the implication for flood management in these locations. We found that the interaction between flood drivers is statistically significant in 10 catchments located around Hainan Island (south) and Shanghai, where surge peaks occur mainly during the typhoon season and around the Bohai Sea (north), where surge peaks occur mainly during the non-typhoon season. We further applied the copula-based framework to model the dependence between surge peaks and associated rainfall and estimate their joint and conditional probability in two specific locations—Hainan Island and the Bohai Sea, where the correlation between flood drivers is statistically significant. We observed that in Hainan Island where most of the surge peaks occur during the typhoon season, extreme rainfall events during the typhoon season are generally more intense compared to annual maxima rainfall. In contrast, around the Bohai Sea where surge peaks occur mainly outside the typhoon season, rainfall is less intense than annual maxima rainfall. These results show that the interaction between extreme surges and rainfall can provide valuable insight when designing coastal and urban infrastructure, especially in highly populated urban areas prone to both coastal and pluvial flooding, such as many Chinese coastal cities.

China
Coastal catchments
Compound flooding
Copula function
Extreme surge
Optimal threshold

http://resolver.tudelft.nl/uuid:9cea195a-959e-494a-8737-7eea5ac2a5d5

https://doi.org/10.1007/s13753-023-00482-1

2095-0055

International Journal of Disaster Risk Science, 14 (2), 269-279

Institutional Repository

journal article

© 2023 H. Xu, E. Ragno, Jinkai Tan, A. Antonini, J.D. Bricker, Sebastiaan N. Jonkman, Qing Liu, Jun Wang