The Effects Of Green Space Layout On Urban Waterlogging Based On SWMM Model

Many studies have shown that urban green space has sponge effect,it can mitigate the waterlogging problems caused by urbanization,and the spatial layout of urban green space will bring a certain impact on the urban waterlogging.This research had broken through the conventional statistical analysis method by using ArcGIS software to assist SWMM model for theoretical modeling analysis,and then took a region in sponge pilot Hebi as a practical case to explore the impact of urban green space's layout on urban waterlogging,aimed to provide a theoretical reference for the layout planning of urban green space in the future.After modeling analysis,this research has mainly drawn the following conclusions:(1)Urban green space can mitigate the risk of waterlogging because of its own sponge effect,and the sponge construction in Hebi has achieved the goal of no drainage under small rainfall.(2)By using SWMM model to analyze the risk of regional waterlogging,only when the drainage of regional pipeline network is smooth,can the risk of waterlogging be predicted by the peak discharge of the outlet.(3)When the rate of regional green space is a constant,the best layout of urban green space to control regional waterlogging is absolute decentralized distribution,which is better than the absolute centralized distribution;when the green space is centralized at a certain location in the drainage area,the closer the location is to the midstream,the smaller the risk of urban waterlogging will be,the closer the location is to the downstream,the greater the risk of urban waterlogging will be.(4)With the increase of rainfall reappearing period,the impact of urban green space on regional waterlogging gradually weakened under the condition of a certain rate of regional green space.In the above conclusions,"the rate of regional green space is a constant" refers to the green space rate of the case studied in this paper,which is 29.4%.The definition of "absolute decentralized distribution" in this paper is that each sub-catchment keep the existing roof area unchanged,while the green space rate in the remaining area of each sub-catchment are the same.Sub-catchments were divided into "park-type sub-catchments" and "common-type sub-catchments" in "absolute centralized distri-bution",their green space rate was 92% and 14% respectively,and the other underlying surfaces' proportion in the remaining area of each sub-catchment were the same,then the "park-type sub-catchments" were centralized in a certain location of the drainage area.