Validation of urban flood inundation modelling with insurance claims

The accuracy of urban flood inundation modelling is fundamentally limited by the scarcity of ground truth data, which impedes reliable forecasting for disaster risk reduction. This study proposes a novel framework to validate flood model simulations using insurance claim records. We applied a 2D hydraulic model (FloodMap-HydroInundation2D) to simulate a pluvial flood event in Ningbo, China. The simulated maximum inundation extent was validated against georeferenced insurance claims, revealing strong spatial agreement and demonstrating the practicability of such non-traditional datasets. A comparative assessment with social media data further contextualized the performance of the insurance-based validation. Sensitivity analysis highlighted hydraulic conductivity as a key parameter influencing model accuracy, offering valuable insights for parameter optimization. To address inherent locational uncertainties in claims data, a buffer-based validation method was developed and tested, which enhanced the robustness of the model assessment. This work provides a transferable approach for integrating non-traditional observations to improve flood model reliability, thereby supporting flood risk management and emergency decision-making.