绿色基础设施暴雨径流消减效能模拟与影响因素研究

With the increase of urbanization, the impervious surfaces have been increased significantly, which results in floods and water logging events frequently occurred in urban areas. Green infrastructure is an effective measure for mitigating urban flooding due to it has a good stormwater runoff reduction effect. How to accurately and quantitatively evaluate and simulate the stormwater runoff reduction effectiveness of green infrastructures, and according to the different objectives to optimize the structure and combination of green infrastructures, which is the essential to promote green infrastructures practice widely implemented in cities. In this study, the artificial simulated rainfall experiment and green infrastructures' scale model were designed to analyze the stomwater reduction effectiveness of different green infrastructures, and a simulation model was developed to quantify the reduction effectiveness of green infrastructures on stormwater runoff, the scenario simulation was used to assess the different structures and combinations of green infrastructures on their reduction effectiveness of stormwater runoff. This work is intended to provide scientific basis for widespread use of green infrastructures in urban areas.

当前快速的城市化进程使得城市不透水地表面积大量增加，导致了城市地区内涝事件频繁发生。绿色基础设施具有良好的暴雨径流消减作用，是城市洪涝调控的有效措施之一。如何准确地定量评估和模拟绿色基础设施暴雨径流消减效能，以及根据不同目标来优化绿色基础设施构建结构和组合方式选择，是将绿色基础设施在城市大范围推广实践的关键所在。本项目通过绿色基础设施缩尺模型和人工降雨模拟实验，研究不同绿色基础设施暴雨径流消减效能特征，构建绿色基础设施暴雨径流消减模拟模型，基于情景模拟分析不同绿色基础设施结构和组合对暴雨径流消减效能的影响，提出适合干旱区的绿色基础设施最优结构和组合方式，为绿色基础设施实践在城市的推广和实施提供科学基础。

绿色基础设施是缓解城市内涝和面源污染的有效措施之一。本项目通过正交实验设计绿色基础设施缩尺径流小区，开展了连续三年的人工模拟降雨实验，评价了绿色基础设施结构因子对降雨径流和污染物滞留的影响，分析了雨强和基质前期含水量对绿色基础设施径流开始时间和径流滞留率的影响。结果显示：基质材料对绿色屋顶径流滞留的贡献最大（53.9%），基质厚度对绿色屋顶径流滞留的贡献次之。坡度和植被对绿色屋顶径流滞留能力的贡献小。随着雨强的增加，绿色屋顶的径流滞留率显著降低和产流开始时间推迟。基质前期含水量是反应绿色屋顶降雨径流滞留能力的有效指标。绿色屋顶出流中TSS（总悬浮物固体）、TN（总氮）和TP（总磷）的平均浓度均显著高于传统屋面，是降雨径流中悬浮物固体和氮磷营养物的源。基质材料组成和植被类型是影响绿色屋顶径流中污染物的主要因子。较厚的生长基质会释放出更多的悬浮物固体和氮磷营养物。透水铺装能够显著地消减径流排放和径流峰值，对产流开始时间的消减效果有限。透水砖铺装和透水混凝土铺装之间的径流开始时间和径流滞留率无显著差异。较厚的砂砾层能够显著地延迟产流、增加径流滞留率和提高污染物负荷消减率。下凹式绿地能够滞留不透水地表流入的雨水，可以有效地延迟产流。随着下凹深度的增加，径流开始时间推迟，径流速度变缓，径流峰值和累积径流深降低。三种绿色基础设施情景下，北京城区径流系数分别减少了2.7%，15.3%和22.2%。上述结果为绿色屋顶结构的设计提供科学建议，同时为绿色基础设施实践在城市的推广和实施提供科学基础。