A GIS-based lightweight modeling approach for flood simulation in the Jieyuanju River of the Wushagang Basin

Abstract The increasing frequency of extreme rainfall events has led to severe rainstorm-induced flooding in urban and rural areas, posing significant threats to resident safety and socio-economic stability. To address the complexity of flood inundation analysis in data-scarce small and medium-sized river basins, this study proposes a scalable, GIS-based flood forecasting framework by coupling a one-dimensional hydrodynamic model with a Python-automated scripting system. Designed for large-scale deployment across extensive small watersheds and communities in the rural–urban fringe of Hubei Province, the framework utilizes DEM-based grid discretization to indirectly simulate overland flow propagation. As a representative pilot case for validation, the Wushagang sub-watershed (specifically the Jieyuanju River section) was selected. Under various extreme rainfall scenarios, the spatiotemporal evolution of storm-induced flooding was simulated to verify the framework’s capability in reproducing historical inundation patterns without extensive gauge data. Results from the pilot study demonstrate that flood extent expands markedly with longer return periods, with high-risk zones predominantly located in low-lying areas. The findings confirm the transferability and efficiency of the proposed framework, providing valuable technical support for flood risk assessment and disaster management in ungauged rural and urban fringe regions.