| Accompanied by China’s rapid urbanization process, the area of urban impervio us is rapid expansion. The number of urban grassland and wetlands are continue to decrease. Changed the nature of surface rainwater runoff storage capacity, urban storm water runoff is increasing, resulting in urban waterlogging occur frequently. Through the construction and implementation of the sponge city, improving the storage capacity of the urban surface, let the hydrological characteristics of urban development are close to the hydrological features before development. Al eviate urban waterlogging, reduce urban surface rainwater runoff, reduce runoff pollution load has become a hot researc h at home and abroad. Under the guidance of "sponge city" concept. In this paper, Dali Haidong District as the study area, analysis and design of the study area to obtain the city "sponge"- sunken green space design parameters. According to local rainfall data and the model recommended parameters to obtain the model parameters, and use the storm water management model(SWMM) to simulation and analysis the control effect of the lower concave green space on runoff. The research contents and results are as follows:(1) Use the GIS technology, based on the DEM data, drainage network data and land use planning data, to generalizing drainage areas and drainage network. In the study area, a total of 141 sub catchments, 127 pipeline section, 22 discharge outlet, 128 network nodes, the study area SWMM model constructed on this basis.(2) In the study area land use data, soil data, urban green space system data, meteorological data based, using the control variable method to obtain each subwatershed units sunken green space design parameters. And optimized in terms of sunken green plant selection, sunken green vertical design, sunken lawn and storm sewer connections, etc., obtained the sunken green space design parameters can meet the requirement of actual situation(3) In SWMM model using the storm intensity formulas of Xiaguan area, design the rainfall that under different rainfall intensities(P=0.25,P=0.5,P=1,P=2,P=5), different type of rain(r=0.286,r=0.5,r=0.7) and rainfall duration is 1 hour. Use the process in Chicago rainfall pattern to obtain the study area rainfall simula t io n process lines.(4) In the SWMM model, we designed different rainfall intensity and rainfall same two scenarios to simulate and analyze ordinary green and sunken green space on the impact of storm water runoff situation. The following conclusions are obtained.When rainfall return period p=0.25 a rainfall duration is 1 hour, in Haidong new district sunken green space on urban runoff control rate reached about 85.85%. When rainfall return period p=0.5a rainfall duration is 1 hour, in Haidong new district sunken green space on urban runoff control rate reached about 87.53%. When rainfall return period p=1a rainfall duration is 1 hour, in Haidong new district sunken green space on urban runoff control rate reached about 85.77%. When rainfall return period p=2a rainfall duration is 1 hour, in Haidong new district sunken green space on urban runoff control rate reached about 87.2% When rainfall return period p=5a rainfall duration is 1 hour, in Haidong new district sunken green space on urban runoff control rate reached about 86.46%. When rainfall return period p=1a rainfall duration is 1 hour, sunken green space can delay maximum runoff occurs 5min~10min.At three different type rain conditions, when the rain peak is in the middle, sunken green space cannot effectively reduce the runoff of rain. When the rain peak is in the middle, peak runoff is the largest in the rain water discharge port. In the other two cases rainwater runoff is not very different. Specifically, the location of the peak r is closer to the middle position, rainwater runoff bigger, the smal er and the contrary. When the total rainfall under the same premise and the rain peak is in the middle, which is more easily to lead to urban waterlogging occurs. |
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