Response analysis of impervious surfaces spatial distribution to surface runoff generation and confluence based on physical experiments

Rapid socio-economic development has accelerated urbanization, making it imperative for urban water flood management to accurately assess the influence of impervious surface spatial distribution on rainfall-runoff processes. To analyze the response relationship between impervious surface spatial distribution and rainfall runoff, this study employed physical experiments to construct 36 spatial distribution scenarios (Six imperviousness ratios) and conducted simulations under uniform rainfall intensity. The effects of impervious surface distribution on surface runoff processes and the relationship between landscape pattern indices and surface runoff elements were analyzed based on three metrics: runoff coefficient, peak runoff and peak time. The results show that the spatial distribution of impervious surfaces significantly affects the runoff coefficient, peak runoff, and peak time. A concentrated distribution provides the most effective runoff reduction. However, no clear pattern was observed in its influence on peak time and peak runoff magnitude. A high correlation was identified between the SPLIT (Splitting index) and the runoff coefficient, with a concomitant decrease in the runoff coefficient with increasing SPLIT. The findings provide a scientific basis for urban runoff control.