降雨强度及降雨间隔对低影响开发雨洪控制的影响及分析

Effect and Analysis of Rainfall Intensity and Interval on Stormwater Control of Low Impact Development

低影响开发(low impact development,LID)是一种采用微观尺度和分散式设施从源头实现雨洪控制的理念。以长沙市某居民小区为研究区域,基于城市排水管网模拟系统建立了现状无LID、绿色屋顶、下凹式绿地、渗透铺装、植被浅沟及上述四项LID设施组合的六种不同用地场景的排水管网水力模型。结合管道的承载能力全面评价各项LID措施在不同降雨强度、不同时间间隔多场降雨的雨洪控制效果。结果表明:渗透铺装、下凹式绿地、绿色屋顶措施的径流控制和削峰作用相对较好。降雨强度较低时,LID措施的雨洪控制较好,与排水管渠系统联用,可以有效降低内涝风险。绿色屋顶和下凹式绿地的径流削减能力对降雨强度变化较敏感,渗透铺装和植被浅沟相对稳定。连续降雨条件下各项LID的雨洪控制效果不佳,绿色屋顶和植被浅沟的削峰能力严重降低。随降雨间隔的加大,各项LID措施的功能缓慢恢复。

Low Impact Development （LID） is a concept of rainwater control by micro-level and distributed facilities at the source. Based on Digital Water Simulation （DS）, the drainage network model was established under 6 land setting conditions with no LID, green roof, sunken lawn , porous pavement ,vegetative swale and unions of the above four, taking a residential district in ChangSha as a example. The influence of different rainfall intensity and intervals on the effect of stormwater control of the above LID practices, on consideration of the load capacity of the pipe network ,was evaluated.The results showed that porous pavement，sunken lawn and green roof had relatively obvious effect on runoff control and reducing peak flows. The LID practices could effectively control the stormwater and lower the risks of waterlogging. The effect of runoff control of green roof and sunken lawn was more sensitive to rain intensity change, while porous pavement and vegetative swale remained stable. The LID practices had a poor performance under consecutive rainfall .The capacity of reducing peak flows of the green roof and vegetative swale practices was badly weakened. The function of the LID practices recovered gradually with the increase of rain intervals .