基于SWMM的地表径流量与城市下垫面和降雨特征关系的空间分析——以中国科学院大学雁栖湖校区为例

Spatial analysis of the effects of urban underlying surface and rainfall events on surface runoff based on SWMM: a case study of Yanqi Lake campus of University of Chinese Academy of Sciences

以中国科学院大学雁栖湖校区为例,用城市雨洪管理模型(SWMM)模拟2016—2017年48场降雨事件中所有子汇水小区的径流过程;在验证可靠的基础上,探讨径流量空间分布与降雨和下垫面的关系,是开展防汛工作的重要基础。结果表明,径流量高值区多位于沥青小区,而低值区多位于绿地小区。沥青最易产流,绿地最不易产流。砌砖易产生中等量级的径流,混凝土较砌砖更易产流,但二者在不同降雨事件下的产流规律相似。沥青小区和砌砖小区的地表径流量均与坡度呈极显著或显著线性正相关关系。对沥青-砌砖和沥青-绿地小区,将非渗透面积比例(PIC)降至60%可明显控制其暴雨和大雨径流。要明显控制大暴雨径流,可将沥青-绿地小区的PIC降至30%以下;但降低PIC对沥青-砌砖小区大暴雨径流的控制作用不明显。研究结果可为海绵城市建设和城市内涝防洪提供理论依据和决策建议。

The Yanqi Lake campus of University of Chinese Academy of Sciences was taken for a case study.Stormwater management model(SWMM)was used to model water overflow processes in all the subcatchments in the study area during the 48 rainfall events in 2016 and 2017.The relationships of spatial distribution of surface runoff with rainfall and underlying surface were explored.The results showed that there occurred higher runoff in the subcatchments with asphalt land cover,while there occurred lower runoff in the green-cover subcatchments.Asphalt land cover had the greatest possibility to produce overflow,green cover had much weak possibility,and brickwork cover was more likely to produce intermediate runoff.Although concrete land or roof cover produced more overflow than brickwork cover,they had similar patterns of producing runoff under different rainfall events.The surface runoff values of asphalt or brickwork land cover were linearly positively correlated with the slope value.For the subcatchments with asphalt-brickwork or asphalt-green cover,percent impervious cover(PIC)should be reduced to be below 60%to significantly control rainstorm and heavy rain runoff.To significantly control heavy rainstorm runoff produced within the subcatchments with asphalt-green cover,PIC should be lower than 30%.However,for the subcatchments with asphalt-brickwork cover,decreasing impervious area did not have obvious effect on mitigating heavy rainstorm runoff.The study may provide theoretical basis and decision-making suggestions for sponge city construction and urban flood prevention and control.