Analyzing urban form influence on pluvial flooding via numerical experiments using random slices of actual city data

•Urban flooding is a growing problem, causing considerable harm to people and infrastructure.•An analysis of the influence of urban forms on the surface flow of urban flooding was conducted.•The results showed that in different scenarios, urban forms had some impact on urban flow.•However, the impact patterns were relatively complex.•The results could help flood-sensitive urban design and flood risk management practitioners. Diversified urban forms resulting from urbanization is a pivotal factor influencing urban pluvial flooding. A systematic analysis of the influence of urban forms on the surface flow of urban pluvial flooding was conducted. We obtained 1,000 sets of 1 km × 1 km urban form data that met quality control requirements using a random slicing method, based on actual urban underlying surface data, with nine spatial characteristic parameters used to tabulate the urban forms. A two-dimensional hydrodynamic model was employed to simulate the surface flow of the urban flood inundation. Scenario simulations and analyses were conducted for three slopes (1, 2, and 3 %) and three rainfall scenarios (with return periods of 5, 20, and 100 yr). The results showcased that, in different scenarios, the urban forms had some impact on urban flow variables and their processes, although the impact patterns were relatively complex. Regarding the process of urban flow variables, the urban forms affected the rate of decline in flood variables during the descending stage. The correlation analysis highlighted that road density, road area proportion, spread contact among various patch types, and uniformity across patches have important impacts on the maximum flood volume and maximum inundated area. The research results could help deepen our understanding of the formation mechanisms of urban pluvial flooding, flood-sensitive urban design, and flood risk management.