城市有效不透水面积空间布局对降雨-径流过程的影响机理研究

Research on the impact mechanism of the spatial distribution of effective impervious area on the rainfall-runoff process is the hotspot and the difficulty in investigating the urbanized hydrological effect. The project will employ a research approach combining field observation, mechanism analyzation and model simulation and select the sponge test base in Zhenjiang City as a case study site. Firstly, different underlying surfaces of pervious sponge facilities and impervious area are chosen to carry out the whole, multi-element storm-runoff process experiment by considering different magnitudes and temporal distributions of storms and initial soil moisture, systematically revealing the runoff generation and concentration mechanism under different combinations of different rainfall types, initial soil moisture content, and underlying conditions. Secondly, a distributed urban flood model which could explicitly reflect the spatial distribution of the effective imperviousness is built up by coupling with surface rainfall-runoff model, pipe network hydrodynamic model and storm inundation model together. Thirdly, based the different spatial distribution scenarios of the effective impervious area, the hydrological effect under different rainfall types and initial soil moisture condition will be simulated thereafter, disclosing the influence mechanism of the spatial distribution variation of effective imperviousness on the rainfall-runoff process. The output of the research could not only enrich and develop the theories of urban runoff generation and concentration as well as the urban flood and waterlogging preventation, but also is of great practical values in supporting urban construction layout of sponge cities and promoting the guarantee capability of urban water security.

有效不透水面空间布局变化对降雨-径流过程的影响机理，是研究城市化水文效应的热点和难点。本项目拟依托镇江市海绵试验基地，采取实地观测、机理分析、模型模拟为一体的研究途径，选择透水性海绵设施及不透水面下垫面，针对不同量级和时程分配次降雨及初始土壤湿度条件，开展次暴雨产汇流全过程多要素对比观测实验，系统揭示不同雨型-初始土壤含水量-下垫面组合条件下的产汇流规律；构建并集成地表降雨径流模块、管网水动力模块和暴雨积水模块且能够显式考虑有效不透水面空间布局的分布式城市雨洪模型；以防洪和降低内涝风险为目标设定有效不透水面空间分布情景，模拟不同有效不透水面空间布局在不同雨型和初始土壤含水量条件下的水文效应，揭示城市有效不透水面空间布局变化对降雨-径流过程的影响机理。研究成果将丰富和发展城市产汇流和城市洪涝灾害防治理论，又在支撑我国海绵城市布局建设、城市水安全保障能力提升等方面具有重要实用价值。

依托镇江海绵科研基地，针对不同量级和时程分配次降雨过程及初始土壤湿度条件，实地观测不同下垫面降雨径流过程，评估场次降雨与不同设施出流相关性，分析不同城市下垫面在不同降水量级及降雨雨型下的水文性能，以及运行时间对城市下垫面水文效益的影响。结果表明：透水铺装类海绵设施的降雨径流关系呈单一式；而绿植类则表现为分段式；暴雨条件下不同海绵设施的产流能力和洪峰流量最大，对径流总量消减能力及洪峰流量削减能力最弱，且从暴雨到大雨变化规律比大雨到中雨变化规律更显著；海绵设施的水文性能受到降雨雨型、平均降雨强度和最大单位降雨强度等因子多重复合影响；车行透水砖运行一年后，其产流能力与洪峰流量分别显著提升而径流控制能力显著减弱。.基于地形、管网等数据，研制耦合地表产汇流模块、管网水动力模块和暴雨积水模块的城市分布式雨洪模型，采用Morris筛选法分析参数的敏感性并进行参数的率定和验证；模拟了不同城市下垫面空间布局在不同历时、重现期设计暴雨条件下的降雨径流过程，定量评价和比较了不同情景下的雨洪调控效应。结果表明与有效不透水面相比，采用总不透水面积表征流域不透水性使模拟洪量偏低；对于10年一遇及以下重现期设计暴雨，透水铺装或雨水花园均具有较好的雨洪调控作用，但对于重现期超过10年一遇的设计暴雨，其雨洪调控效果大大降低；透水铺装和雨水花园的组合可以有效地调控20年一遇及以下重现期设计暴雨的所形成的径流。.以国家第一批海绵试点城市镇江市为例，构建了由气象降雨监测、下垫面监测、陆域海绵设施、项目地块、排水分区监测、河湖、流域监测等组成的多层级有机嵌套海绵城市监测对象体系，明确其监测指标、布点原则、监测频率、数据的筛选/识别及有效利用，并与模型体系相结合形成可复制的技术模式，对评价海绵城市建设成效与优化运行、加强城市内涝治理实施、系统化全域推进海绵城市建设具有重要理论意义和实用价值。