Virtual Reality–Based Visualization of Urban Flood Dynamics Using SWMM

Urban flooding and water pollution have become increasingly severe challenges worldwide as a result of climate change and rapid urbanization, posing substantial risks to public safety, urban infrastructure, and environmental quality (Mark et al., 2004; Andrade et al., 2018). Intense rainfall events frequently exceed the capacity of urban drainage systems, leading to surface inundation and the transport of pollutants into receiving water bodies. To address these issues, numerical hydrological and hydraulic models have been widely applied to simulate urban runoff processes, sewer network performance, and water quality dynamics. Among these models, the Storm Water Management Model (SWMM) is one of the most commonly used tools for analyzing urban drainage systems and pollutant transport under various rainfall scenarios (Gironás et al., 2010). Despite its widespread adoption and robust modeling capabilities, SWMM primarily presents simulation outputs in the form of numerical tables and two-dimensional graphs. This conventional output format limits intuitive interpretation and restricts the ability to analyze spatial and temporal flood dynamics within complex urban environments (Zhang et al., 2016). This study proposes a virtual reality (VR)–based visualization framework that integrates SWMM simulation results with the Unity game engine to enhance the interpretability of urban flooding and water quality simulations. In the proposed framework, rainfall–runoff processes, inundation depth, and pollutant diffusion are first simulated using SWMM for a selected urban catchment. The resulting hydrological and hydraulic outputs are then converted into data formats compatible with the Unity environment. A three-dimensional urban model is constructed to represent surface topography and drainage infrastructure, enabling the visualization of flooding processes in a spatially explicit manner. Flood extent and water depth are visualized dynamically within the virtual environment, allowing users to observe flood propagation over time. In addition, pollutant transport is represented using color-based visualization techniques, where variations in color indicate changes in pollutant concentration. This approach provides an intuitive representation of water quality degradation during flood events. The VR system supports interactive exploration through the use of head-mounted displays and motion interfaces, enabling users to navigate the virtual urban space and examine flooding and pollution patterns from multiple perspectives. The immersive nature of the VR environment enhances spatial perception and facilitates a more comprehensive understanding of complex flood processes compared to traditional two-dimensional visualization methods. By allowing users to directly experience simulated flood scenarios, the proposed framework supports more effective interpretation of model results and improves communication of flood risk information. The results of this study demonstrate that VR-based visualization has significant potential as a decision-support tool for urban flood risk assessment, emergency response planning, and disaster management training.