Urban flooding has become one of the most common natural hazards threatening people’s lives and assets globally due to climate change and rapid urbanization. Hydraulic structures, e.g., sluicegates and pumping stations, can directly influence flooding processes and should be represented in flood modeling and risk assessment. This study aims to present a robust numerical model by incorporating a hydraulic structure simulation module to accurately predict the highly transient flood hydrodynamics interrupted by the operation of hydraulic structures to support object-level risk assessment. Source-term and flux-term coupling approaches are applied and implemented to represent different types of hydraulic structures in the model. For hydraulic structures such as a sluicegate, the flux-term coupling approach may lead to more accurate results, as indicated by the calculated values of NSE and RMSE for different test cases. The model is further applied to predict different design flood scenarios with rainfall inputs created using Intensity-Duration-Frequency relationships, Chicago Design Storm, and surveyed data. The simulation results are combined with established vehicle instability formulas and depth-damage curves to assess the flood impact on individual objects in an urbanized case study area in Zhejiang Province, China.

Flooding increasingly threatens lives and property under climate change and rapid urbanization. Mobile pumping stations offer a practical and cost-effective solution for flood protection in low-lying, densely populated coastal areas. However, previous studies typically used simplified methods to represent pump stations, and few have integrated pump operations into high-resolution simulations of multi-source urban flooding. This study develops a High-Performance Integrated Hydrodynamic Modeling System–Pumping System Model–Flood Impact Assessment Model (i.e., HiPIMS-PSM-FIM) framework to evaluate object-level exposure and quantify the benefits of pumping. In this framework, the PSM is two-way coupled with HiPIMS using a Source Coupling Method to simulate spatiotemporal flood dynamics. The results are then integrated with exposure data through FIM to identify risks and support mitigation strategies. The framework is applied to a multi-source flood in Yuhuan City, Zhejiang Province, China, at 3 m resolution, and shows strong agreement with field surveys. Vulnerability analysis shows Children > Sedans > Adults > SUVs, with educational facilities facing highest risks. Sensitivity results to pumping rates demonstrate that mobile pumping can reduce the affected population by 82% and decrease impacts on key facilities and roads, demonstrating the framework’s robustness and practical value for enhancing urban flood resilience.