Compound Floods in the Pearl River Delta: Research Highlights Advances in Hydrology and Earth System Sciences

Recent research on hydrology and earth system sciences has shed light on the devastating effects of compound floods, which occur when various flood processes, such as extreme storm surges and heavy precipitation, merge to cause catastrophic damage. The study, conducted by researchers from Tsinghua University, aimed to develop a coupled land-river-ocean model that could accurately simulate the interactions between different flood processes. The model was applied to the Pearl River Delta region and demonstrated excellent agreement with observational data, with Willmott skill values of 0.96 and 0.88 for river flow and ocean surface elevation, respectively.

Key Takeaways:

• The study highlights the importance of considering the interactions between different flood processes, including storm surges, storm waves, astronomical tides, river flow, and precipitation, to accurately simulate compound floods.
• The developed coupled land-river-ocean model was shown to be effective in simulating compound floods induced by tropical cyclones in the Pearl River Delta region, with a coastal inundation area that covers approximately 80% of the area identified by remote sensing.
• The research emphasizes the significance of river base flow, which contributes to 2% to 30% of the total flood volume, depending on the landfall time of the tropical cyclone.
• The study also highlights the importance of the completeness of the coupling method in achieving numerical accuracy, which can substantially impact the simulation results.
• The research demonstrates the effectiveness of the coupled model in simulating compound floods, which can provide valuable insights for flood management and mitigation strategies in large river delta regions.

Statistics:

• The coupled land-river-ocean model demonstrated a Willmott skill value of 0.96 for river flow and 0.88 for ocean surface elevation.
• The coastal inundation area obtained with the model covers approximately 80% of the area identified by remote sensing.
• River base flow contributes 2% to 30% of the total flood volume, depending on the landfall time of the tropical cyclone.
• The study analyzed a tropical cyclone event in the Pearl River Delta region, where precipitation accounts for 5% to 15% of the total flood volume.

Sources:

• Development of a land-river-ocean coupled model for compound floods jointly caused by heavy rainfall and storm surges in large river delta regions (Hydrology and Earth System Sciences - http://www.hydrology-and-earth-system-sciences.net/).
• National Natural Science Foundation of China