Enhancing Flood Risk Assessment through Improved Compound Flood Modelling for Tropical Cyclones

Coastlines are vulnerable to concurrent high sea levels, intense rainfall, and extreme river discharge from tropical cyclones, elevating flood risks beyond individual hazard predictions. Modelling compound flooding from tropical cyclones is essential for generating regional flood risk assessments and forecasts for current and future climate scenarios, and subsequently taking proactive measures in vulnerable communities to mitigate these risks. However, numerical models of compound flooding are often poorly validated and their sensitivity to climate change is uncertain, limiting their effectiveness. This research aims to achieve two technical objectives: 1) to develop improved and validated compound flood modelling capabilities along the Mozambique coastline; and 2) to simulate compound flooding from tropical cyclones. Coastal water levels from ADCIRC model will serve as downstream boundary conditions, river discharge from ECLand-CaMa model will be used as upstream boundary conditions and precipitation data across the study domain from ERA5 will be incorporated to drive the LISFLOOD-FP hydrodynamic model for on land inundation simulation. Uniquely, we will evaluate the model using surface water height observations from the recently launched Surface Water and Ocean Topography (SWOT) satellite mission, the first satellite capable of observing compound water surface profiles with centimetric vertical accuracy in estuaries, offering new calibration and validation opportunities. This comprehensive approach will enable the LISFLOOD-FP model to simulate compound flooding events. By integrating diverse data sources, we aim to enhance our understanding of flood risks associated with tropical cyclones and support more effective early warning and mitigation strategies.