基于SWMM情境模拟的外源雨水型公园绿地雨洪调控效果研究

公园绿地相对其他城建区拥有大面积的透水性下垫面,可以配合城市管网接纳外源雨水,有效地参与城市雨洪调控。本文以迁安市滨湖东路东侧绿化带为研究对象,对研究区域进行合理概化,并在区域内建立公园绿地的低影响开发(LID)模式和传统开发模式,根据项目要求引入外源雨水,运用SWMM模型模拟不同重现期(1年一遇、2年一遇、5年一遇、10年一遇、20年一遇)1 h降雨下的两种开发模式,对比分析排放口的径流总量、峰值流量和峰现时间,以及2年一遇1 h降雨下各单项LID设施对径流的调控效果。结果表明:1)SWMM模型可以量化模拟LID设施对雨水径流的控制效果,为城市进行低影响开发建设提供技术支持和理论依据;2)在进行制定径流控制目标时,应结合场地现状情况,规划外源汇水面积;3)LID设施对城市雨洪具有良好的调控效果,可以减少径流总量,降低径流峰值,推迟峰现时间。采用LID模式建设的外源雨水型公园绿地在1年一遇至20年一遇的降雨条件下,对径流总量的削减率为100%~37.69%,对峰值流量的削减率为100%~40.55%,峰值消失或出现时间迟滞135~24 min。各项LID设施对径流总量削减的效率排序为:下沉式绿地＞组合型＞植草沟＞生物滞留池＞透水铺装;对峰值流量消减的效率排序为:下沉式绿地＞组合型＞生物滞留池＞植草沟＞透水铺装;对推迟洪峰出现时间的效率排序为:组合型＞下沉式绿地＞生物滞留池＞植草沟＞透水铺装。4)公园绿地在进行LID设计时,应考虑防灾避险等其他功能需求。 

Research of storm flood regulation efficiency of the low impact development of exogenous-rainwater park based on the SWMM simulation

Compared with other urban construction area, the park area has large well-drained underlying surface, which can work with the city pipe network to accept more exogenous rainwater and regulate the storm flood. This study generalizes the research area and constructs the low impact development ( LID) model and traditional development model through a case study of Binhu East Road Park in Qianan City. The research introduces the exogenous rainwater and applies the storm water management model (SWMM) in 1 hour rainfall event with different return periods (once every 1, 2, 5, 10 and 20 years), simulating the regulative effect of two development models in total runoff, peak flow as well as time of peak flow appearance and the control efficiency of single LID facility under once 2-year 1 hour rainfall event. The results show that:1 ) The SWMM model can stimulate the LID facilities’ regulation of rainwater, and provide the technical supports and theory evidences for urban construction. 2 ) When setting goals of runoff regulation, we should plan the catchment sizes of exogenous-rainwater combined with the site current situation. 3) LID model has a good effect on storm flood regulation, can decrease the total runoff, peak flow and delay the time of peak flow occurrence significantly. Under the rainfall return periods from 1 to 20 years, the park construction based on the LID model can reduce total runoff, and peak flow by 100% -37. 69% and 100% -40. 55%, and eliminate the peak flow or delay the time of peak flow occurrence by 135 -24 min, respectively. The efficiency of LID facilities decreasing total runoff ranked as: rain garden > combined system > vegetative swale > bio-retention cell > permeable pavement. The efficiency of LID facilities decreasing peak flow ranked as:rain garden>combined system>bio-retention cell>vegetative swale >permeable pavement. The efficiency of LID facilities to postpone the time of peak flow occurrence ranked as: combined system > rain garden > bio-retention cell >vegetative swale>permeable pavement. 4) When designing a low impact development park, we should consider other functional requirements such as disaster prevention.