维护良性水循环的城镇化LID模式:海绵城市规划方法与技术初步探讨

海绵城市是低影响开发模式(Low Impact Development,LID)的重要途径,也是解决我国城市水问题的重要举措。论文从良性水循环理念的角度,针对城市防洪排涝、面源污染控制以及雨洪资源化利用等三大核心问题,以城市雨洪模拟技术和LID优化技术方法为重点,探讨了支撑海绵城市实施的关键技术方法,构建了具有自主知识产权的城市雨洪模型;并以首批海绵城市试点常德市为例进行了应用研究。研究得出:现状常德城区径流系数在0.33~0.81之间,平均值为0.64;按确保年径流总量控制目标的实现,采用渗、滞和蓄等多种LID消纳各地块径流,城区90%的地块均能达到控制目标,下沉式绿地、透水铺装和绿色屋顶总面积分别为496.75、1 338.15和613.21 hm2,占各地块面积的3.9%~31.4%之间。污染负荷SS削减率在45.0%~47.7%之间,平均削减率为46.1%。常德城区通过实施LID措施,雨洪径流和污染负荷的输出量将显著降低,基本能够达到控制目标。研究为常德海绵城市规划设计提供了重要技术支撑和理论依据,为我国海绵城市规划方法和技术研究提供了参考。

The LID Pattern for Maintaining Virtuous Water Cyclein Urbanized Area: A Preliminary Study of Planning and Techniques for Sponge City

Sponge city is an important Low Impact Development (LID) pattern, and also is a key to solve the urban water issues in China. In this study, we focus on the three core tasks including urban flood control and drainage, non-point source pollution control and urban rainfall-flood utilization, and explore the key technology and methodology to support the implementation of sponge city from the perspective of virtuous-water-cycle (e.g., the numerical simulation and LID optimization techniques), and finally develop an urban rainfall-flood model (HIMS-URBAN). This model is applied in Changde City, which is one of the first batch of sponge city. The results demonstrate that: 1) runoff coefficient in Changde City ranges from 0.33 to 0.81 in current state, with an average of 0.64. 2) Based on the objective of controlling total annual runoff, several LID measures (e.g., infiltration, storage and retention), are employed to consume the runoff from each block. By optimization, the controlling objective can be achieved in 90% of urban blocks. The areas of sunken green space, permeable pavement and green roof are 496.75, 1 338.15 and 613.21 hm², respectively, and the total area of LID measures accounts for from 3.9% to 31.4% of each block’s area. The reduction rate of pollution load SS is between 45.0% and 47.7%, with an average of 46.1%. By adopting the LID measures, the outputs of storm runoff and the pollution load in Changde urban area are remarkably reduced, and the control objective is almost achieved. This study provides great valuable results for construction of sponge city in Changde City, and also gives a good reference of theory and technology for urban planning and design.