植被浅沟在城市雨水管理中的作用机制及调控效应研究

Grassed swale is one of the major facilities for urban stormwater management. The investigation on operation mechanism of grassed swale has a vital significance to improve its effectiveness for stormwater control in different planning control objects, which can also provide reference for technological innovation of other facilities and consummate the technical system of urban stormwater management. Based on the operation mode of grassed swale, the runoff characteristics of the typical urban underlying surface under the different runoff conditions were analyzed. Through analyzing the spatio-temporal variation of the soil matrixes by on-line monitoring, the coupling effects and their influence factors of grass-matrix system for stormwater storage and infiltration were revealed. In addition, purification mechanism, enrichment characteristics, leaching and Loss Risk of typical runoff pollutants in different spatial dimensions of grassed swale were discussed. In different planning control targets, the restrictive factors in the operation of grassed swale were determined. And the comprehensive estimation has been made for the control effectiveness of grassed swale in urban stormwater management. The study has significant scientific significance and application value, which will lay a solid theoretical basis in the establishment of sponge city in China.

植被浅沟是城市雨水管理的一项重要设施。研究植被浅沟的作用机制对提升其在不同规划目标控制下的雨水调控效能具有重要意义，还可为其他设施的技术革新提供借鉴，进而促进城市雨水管理技术体系的完善。本课题基于植被浅沟的运行方式，分析不同汇流情境下城市典型下垫面雨水径流特征；通过在线监测植被浅沟基质含水率的时空变化，揭示“植被-基质”复合系统对雨水蓄渗的耦合效应及其影响因素；探讨典型径流污染物质在植被浅沟不同空间维度的净化机理、富集规律和淋溶、流失风险；率定在不同规划目标控制下影响植被浅沟运行效能的限定性因子，综合评价植被浅沟在城市雨水管理中的调控效应。该课题具有重要的科学意义和应用价值，为我国海绵城市的科学构建奠定坚实的理论基础。

植被浅沟是唯一一项集自然渗透、自然净化功能于一体的用于雨水收集、输送和排放的地表开放性技术设施。本项目研究不同汇流情境下城市典型下垫面雨水径流特征，探讨植被浅沟中“植被-基质”复合系统对雨水蓄渗的耦合效应，揭示植被浅沟中典型径流污染物的净化机理；率定在不同规划目标控制下影响植被浅沟运行效能的限定性因子，综合评价植被浅沟在城市雨水管理中的调控效应。. 研究结果表明：植被浅沟的径流峰值削减率为4.54%～13.49%，径流峰值延后时间为9.4 min～26.37 min，次降雨径流总量削减率为10.32%～35.38%；进水水力负荷和进水模式是植被浅沟的雨水径流峰值调控效能的主要影响因素。植被浅沟雨水径流中TSS浓度去除率为30.49%～89.95%，其污染控制效能主要受进水TSS浓度、进水水力负荷及进水模式的综合影响。植被浅沟的雨水径流TSS负荷削减率为浅沟对径流总量调控和TSS浓度控制双重作用的结果。植被浅沟对城市雨水径流调控主要通过“表层植被+根系系统”联合作用实现，其中，表层植被的拦截作用贡献率最大，在不影响植被正常生长情况下，增大植被密度可提升植被浅沟的雨水径流调控效能。. 深入研究植被浅沟在城市雨水管理中的作用机制及调控效应，为不同雨水控制目标下植被浅沟设计参数的优化提供必要的基础理论支撑，这不仅有利于提高植被浅沟的雨水调控效能，还对其他单项雨水管理设施的技术革新具有重要的科学示范意义，从而促进城市雨水管理技术体系的不断完善，为我国科学构建海绵城市、顺利实施国家水污染防治行动计划以及有效促进生态文明建设奠定坚实的理论及实践基础。