社区尺度绿色基础设施暴雨径流消减模拟研究

Modeling the effects of green infrastructure on storm water runoff reduction at community scale

当前快速的城市化进程导致了城市地区内涝事件频繁发生。绿色基础设施是减轻城市洪涝的有效措施之一。SWMM(Storm Water Management Model)等模型的复杂性使得规划管理者对模型的操作和应用存在困难,而且缺乏对绿色基础设施径流消减机制的展现。目前的研究中,比较单个与综合绿色基础设施配置径流消减效果的研究相对较少。基于水量平衡和城市水文过程,开发了社区尺度绿色基础设施消减作用的暴雨径流模型,并以北京市一典型社区为例,模拟研究了一年一遇和五年一遇两种暴雨条件下不同绿色基础设施配置对暴雨径流流量和峰值的消减效率。结果表明:用两场野外监测的降雨和径流数据验证模型得到的决定系数分别为0.68和0.71,纳什效率系数分别达到0.99和0.96,表明模型是可靠的。在一年一遇和五年一遇两种暴雨条件下,将常规绿地改造成5 cm深度的下凹式绿地,径流量分别减少了8.23%和23.30%,径流峰值分别减少了20.31%和29.11%;在建造300 m3调蓄池的情景下,径流量分别减少了84.90%和20.97%,径流峰值分别减少了88.99%和0.10%;在50%的不透水地表铺装透水砖情景下,径流量分别减少了46.51%和38.52%,径流峰值分别减少了39.96%和35.48%。3种绿色基础设施都可以较好的消减社区暴雨径流,但是随着暴雨强度的增强,下凹式绿地的消减效果略增强,调蓄池的消减效果变差,透水砖铺装的消减效果较稳定。综合3种措施对暴雨径流具有显著消减效果,可以100%消减一年一遇暴雨产生的径流,在五年一遇设计暴雨条件下,分别消减75.47%的总径流量和64.52%的径流峰值。

Rapid urbanization has greatly changed the underlying surface,resulting in frequent floods and waterlogging in urban areas and causing enormous economic damage and loss of life. Of the innovative storm water management strategies,green infrastructure（ GI）,which uses vegetation,soils,and natural processes to manage storm water and create healthier urban environments,has proved to be an effective measure to mitigate urban flooding. The runoff reduction effectiveness of green infrastructure facilities under different scenarios can be simulated by mathematical models. However,complex models like the storm water management model are difficult for planners and managers to operate and apply. Furthermore,they are inadequate in demonstrating the runoff reduction mechanisms of green infrastructure. Although the performance of green infrastructure in mitigating urban flooding has been extensively investigated,few studies have attempted to examine and compare runoff reduction effectiveness between integrated green infrastructure and single green infrastructure facilities under different storm recurrence periods. In this study,a community-scale simulation model based on water balance and urban hydrological processes was developed to quantify the reduction effect of green infrastructure on storm water runoff. A typicalcommunity in Beijing was selected as a case study to assess the reduction effectiveness of different green infrastructure configurations,based on the volume and peak flow of storm water runoff under 1-year and 5-year storm events. Four scenarios of green infrastructure configuration were considered,namely： converting to concave green land; constructing a storage pond; converting to porous brick pavement; and combining the previous three measures. Field-monitored runoff data of two rain events were used to validate the model. The validation results yielded determination coefficients of 0. 68 and 0.71 respectively for the two rain events,while the Nash-Sutcliffe efficiencies were 0. 99 and 0. 96 respectively,indicating that model performance was satisfactory and reliable. For the scenario of concave green space with 5 cm depth,runoff volume was reduced by 8. 23% and 23. 30% and peak flow was reduced by 20. 31% and 29. 11% respectively for 1-year and 5-year storm events. For the 300 m3 storage pond scenario,runoff volume was reduced by 84. 90% and 20. 97%respectively for 1-year and 5-year events,while peak flow was reduced by 88. 99% and 0. 10% respectively. For the scenario in which 50% of impervious surface area was modified to porous brick pavement,runoff volume was reduced by46. 51% and 38. 52%,and peak flow was reduced by 39. 96% and 35. 48% respectively for 1-year and 5-year events.These results indicate that each of the three facilities showed good runoff reduction effectiveness. With increased rainfall intensity,the reduction effectiveness of concave green space,storage pond,and porous brick pavement was slightly enhanced,decreased,and relatively stable respectively. The integrated green infrastructure configuration scenario showed significant reduction effects,with 100% reduction of runoff generated by the 1-year storm; runoff volume and peak flow were reduced by 75. 47% and 64. 52% respectively under conditions of the 5-year storm,as well as showing increased rainwater infiltration and harvesting for utilization. Therefore,the integrated green infrastructure configuration is among the optimal strategies for storm water runoff reduction and rainwater resource utilization in communities.