Validating typhoon-induced rainstorm flood inundation modelling with insurance claims

The impacts of tropical cyclone (TC)-induced rainstorm flooding are projected to worsen due to climate change. Two-dimensional (2D) flood inundation models are essential for capturing the spatiotemporal dynamics of floods. However, the successful application of these models depends on effective validation, which is limited by data availability. Thus, there is an urgent need to develop advanced and reliable flood model validation methods. In this paper, we validate the simulations of a 2D flood model using insurance claims data, offering new insights for improving validation approaches. Hydraulic simulations are conducted via the FloodMap–HydroInundation2D model in a case study of flooding induced by Typhoon Muifa (2022) in Ningbo, a major coastal city in East China. The simulated water depth and extent are generally consistent with the flood records provided by the People's Insurance Company (Group) of China Limited (PICC). A sensitivity analysis reveals that the model is sensitive to both hydraulic conductivity and roughness parameters, particularly hydraulic conductivity. Furthermore, circular buffers with radii of 50–100 m around claim locations are shown to be effective alternative methods for approximating building footprints, thereby improving the validation accuracy. Our work provides a practical approach for validating flood models and offers valuable insights into the enhancement of flood risk management in coastal cities.