The impact of RMD on urban runoff cannot be ignored in urban hydrologic management

Urban floods have been exacerbated globally, associated with increasing spatial-temporal variations of rainfall. However, compared with rainfall variabilities of intensity and duration, the effect of RMD is always ignored. Based on 1313 rainfall scenarios with different combinations of rainfall intensity(RI) and RMD in a typical rainy city of Shenzhen in China, we investigate the urban runoff response in relation to RMD and the spatial feature of rivers. Our results show that the effect of RMD on the peak runoff may reach up to 20%, which will decrease to less than 5% under heavy RI conditions. In addition, we find that the impact of RMD is almost symmetrical and is associated with the direction of the river. The closer RMD is to the Linear Directional Mean of upstream, the larger peak runoff of section is. Our results reveal that RMD is significant to urban peak runoff in the downstream reaches, which should be considered in urban hydrologic model.