LID设施与排水管网协同效应对受纳水体的影响规律识别及调控技术研究

Low impact development can mitigate urban flooding and water pollution and improve the quality of water environment. But the efficiency can only be realized with the participation of drainage systems. LID measures and drainage systems have significant synergy effect on receiving water. However, LID measures and drainage systems are planned and designed separately, which can not effectively reduce the impact from runoff to the receiving water. Therefore, the research focuses on how to design LID measures and drainage systems simultaneously to minimize the impact from runoff to the receiving water. Based on the monitoring of quantity and quality of both LID measures and drainage systems, a model for the synergy effect of LID measures and drainage systems which can simulate the whole process of runoff generation, LID disposing and drainage transporting is to be built. A mass of mathematical experiments are to be carried out intending to identify the influence from the synergy effect of LID measures and drainage systems on receiving water. An optimization model of the synergy effect of LID measures and drainage systems is to be built using multi-objective optimization and a case study is to be carried out based on the optimization model. Systematic optimization suggestions will be given to the case study area according to the calculation result. The results of the research can supply new methods for the designing and planning of LID measures and drainage systems and support the generalization of the Sponge City.

低影响开发能够缓解降雨径流引起的内涝、污染等问题，改善水环境质量，但是，这种效能需要通过排水管网传递才能实现。LID与排水管网对受纳水体的影响存在显著的协同效应。然而，现阶段的规划设计将LID与排水管网相割裂，这样不能高效地控制径流对受纳水体的影响。鉴于此，本研究以“如何协同设计LID与排水管网，使城市降雨径流对受纳水体的影响最小”为核心目标，在对典型排水片区开展LID设施与排水管网水量水质演变过程同步监测的基础上，建立能够模拟“地表径流产生-LID设施处理-排水管网输送”全过程的LID设施与排水管网协同效应模拟模型，通过大规模数学实验识别协同效应对受纳水体影响的规律；利用多目标优化技术开发基于协同效应的LID设施与排水管网优化设计模型，并开展案例应用，为案例区域提出系统优化设计的建议。本研究可以为LID与排水管网的设计提供新的理念与工具，为我国“海绵城市”的建设提供技术上的支撑与保障。

低影响开发设施和排水管网是城市排水系统的重要组成部分，两者之间存在协同效应。但目前它们的规划设计工作是独立进行的，没有从排水系统整体功能最大化和对受纳水体负面影响最小化的角度出发协调二者的关系。为此，本项目开发建立了一套低影响开发设施与排水管网集成模拟和协同优化技术，并引入系统弹性指标，在利用弹性统筹全系统的同时优化低影响开发设施和排水管网，通过多目标优化实现城市内涝削减最大化、系统排放污染物对受纳水体造成的压力最小化并尽可能保障污水厂稳定运行，优化的决策变量则包括低影响开发设施的规模、布局和排水管网的设计重现期。本项目选取河北省迁安市作为案例城市，搭建了案例区排水系统模型，通过大规模采样与模型模拟，分析了低影响开发设施与排水管网之间的协同效应规律，例如下游区域的低影响开发设施布局方案与其它区域方案相比，对受纳水体的平均负荷量减少3.1%-7.5%。进而在案例区域开展了协同优化工作，得到了320个方案组成的帕累托最优规划方案集。进一步分析表明：案例区域中低影响开发设施的面积超过30.5%-32.8%的临界阈值时，协同效应变得不再明显；除非对于弹性有特别偏好，大多数情况下适宜优先选择低重现期（低于5年一遇）的管网；规划方案预算较低时更适于采用低成本的低影响开发设施（以下凹式绿地为代表），反之则更适于采用处理径流能力较强的低影响开发设施（以雨水花园为代表）。案例区域的研究验证了所构建的集成模拟和协同优化技术的可行性和有效性。研究成果可为我国海绵城市建设提供技术方法支撑，案例区域的协同效应规律可以为非案例城市的系统优化设计提供参考依据。