Change of rainfall–runoff processes in urban areas due to high-rise buildings

This study proposes a method to consider the high-rise building in the rainfall–runoff analysis of an urban basin. This study uses a rainfall–runoff model based on the shot noise process to evaluate the relative roles of the building rooftop sub-basin and the wall sub-basin. In addition, the rainfall–runoff experiment is conducted in a laboratory environment to validate the proposed method considering high-rise buildings. The major results of this study can be summarized as follow. (1) The rainfall intercepted by the building wall increases the runoff volume and peak flow, but the longer flow path from the rooftop basin decreases the peak flow. Overall, the role of the building wall is found to be more significant than the rooftop in resulting in increased runoff volume and peak flow. (2) The experimental results also confirm the simulation results. The contribution of the building wall to the peak flow is found to be highly significant, especially when the wind speed is high. For example, when the mean wind speed is 1.11 m/s, the contribution of the building wall to the peak flow is found to be 6.3 – 6.9% and 14.2 – 17.0% for the 1.0 and 1.4 m building height, respectively. (3) The accuracy of the rainfall-runoff model can be improved by considering the building. As the building is considered, the RMSE and the difference of peak flow between the observed and simulated hydrograph decrease in all cases. The results of this study support the idea that, in the urban basin, the contribution of the high-rise building to runoff can be significant.