基于有效不透水面识别的城市雨洪过程模拟研究

Urban stormwater simulation based on recognition of effective impervious area

城市化进程加快带来的不透水面积增加是城市洪涝灾害愈加频繁的重要原因.研究聚焦于不透水面的有效性问题,选取了位于北京市凉水河流域的大红门排水区,借助遥感影像通过实地勘察识别有效不透水面,有针对性地构建SWMM城市暴雨径流模型;通过设置不同重现期暴雨情景,定量分析不透水面空间组合方式对城市洪涝的影响.结果表明:考虑不透水面有效性后,率定期2场降水模拟结果的纳西效率系数较传统模式分别提升了13.51%、1.58%,检验期分别提升了9.79%、18.58%.情景分析的结果表明,当有效不透水面占比由100%降低到25%时,5a一遇暴雨的总径流深和洪峰流量能够削减74.6%和65.8%,100a一遇暴雨的削减率为62.9%和21.8%.因此,考虑不透水面有效性将有效提高雨洪模拟的精度,而改变汇流路径,减少有效不透水面是减轻雨洪灾害的重要措施.

Increased impervious area due to rapid urbanization is one reason for frequent urban flooding.Influence of unconnected impervious areas(UIA)on urban flooding was studied in the Dahongmen catchment in Liangshui River basin of Beijing.Field investigation and remote sensing image recognition were used to recognize distribution of UIA in Dahongmen catchment,with integration into the Storm Water Management Model(SWMM).Influence of UIA was also studied with rainstorm scenarios in different recurrence periods and at different UIA proportions.Nash-Sucliffe coefficient of 2 rainstorms in calibration period was improved by 13.21%and 1.58%after taking into account of UIA,Nash-Sucliffe coefficient of 2 rainstorms in verification period was increased by 9.79%and 18.58%.Scenario analysis showed that total runoff depth and peak flow of frequent rainstorms(T=5 a)decreased by 74.6%and 65.8%with the proportion of UIA reduced to 25%,while reduction in the rate of rare rainstorms(T=100 a)decreased by 62.9%and 21.8%.Since effectiveness of impervious area improves accuracy of flooding simulation,changing confluence path to increase UIA is an important measure to reduce flooding damage.