Integrating Hazard and Vulnerability Framework with Source–Sink Theory for Urban Flood Risk Assessment and Management: A Case Study of Beijing

Under the dual pressures of intensified global climate change and rapid urbanization, the risk of urban flooding disasters in China shows significant spatiotemporal heterogeneity. Traditional risk assessment methods primarily rely on weighted superposition techniques to identify high-risk areas, making it difficult to reveal the risk generation mechanism and spatial transmission process and thus leading to the disconnection between disaster reduction measures and the dynamic evolution of risks. In response to these limitations, this study takes Beijing, a megacity, as the object, introduces the “source–sink” theory to propose a dynamic analysis framework of “generation–conduction–convergence” of risks, and establishes a risk conduction topological model. The research results show that 82% of the area in Beijing is at a medium-low risk level, but a significant high-risk concentration zone is formed in the central and eastern regions, and its spatial distribution is strongly correlated with the center of heavy rain, population density, and economically active areas. Through the “source–sink” theory, 17 key risk corridors and 33 key risk nodes are identified. On this basis, targeted flood management strategies are proposed. This study not only provides a spatial optimization plan for flood control and governance in the Beijing–Tianjin–Hebei urban agglomeration, but also contributes to the empirical paradigm of urban rainstorm flood risk management in China for the global climate change context.