Predicting and Mitigating Urban Flooding: A Framework for Shallow Water Surface Flow, Precipitation and Soil Infiltration Modeling based on multiPhysicsFoam
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Extreme rainfall events are increasing in frequency and intensity, posing a significant flood risks to urban areas and critical infrastructure. To support flood risk assessment and the design of mitigation strategies, this work presents a novel numerical framework for simulating rainfall-driven surface flooding within the OpenFOAM environment. The framework is based on a shallow water equations (SWE) solver implemented in the multiPhysicsFoam framework [1], enabling multi-physics and multi-domain coupling. The framework supports streamlined setup, execution, and post-processing of large-scale studies, including the use of GIS-derived data within the automation workflow. The proposed model is capable of handling temporally varying rainfall events and supports multiple infiltration formulations that account for spatially heterogeneous soil properties. Established infiltration models, such as the Horton and Green–Ampt formulations [2], are incorporated to represent different soil types and surface conditions. The SWE implementation builds upon existing shallow water solvers in OpenFOAM, extending them through integration into the multiRegionFoam framework and coupling with additional physical processes. A key contribution of this work is the development of an automated simulation pipeline that enables users to efficiently conduct flood risk analyses and systematically investigate flood mitigation strategies. In particular, active mitigation measures such as pump trucks and drainage systems are modeled in a fully coupled manner, allowing for the assessment of their effectiveness under different rainfall scenarios. The solver is rigorously verified against standard benchmark test cases to establish numerical accuracy and robustness. Application to urban-scale scenarios demonstrates the framework’s capability to capture essential flooding dynamics, evaluate the role of infiltration processes, and quantify the impact of active water removal strategies.
