1、 Project introduction
　　
Xicheng District, located in the center of Beijing, is the functional core area of the capital, covering an area of 50.7km2, with the longest distance from east to west of 7.1km and the longest distance from north to south of 11.2km. It is located under the alluvial fan of Yongding River, with plain landform. The natural terrain trend is basically high in the northwest and low in the southeast, with an average elevation of about 40m. Warm temperate continental semi humid and semi-arid monsoon climate, the average annual rainfall is about 575mm, the water area is 1.55km2, 9 rivers. Xicheng District is divided into 15 sub district offices with a permanent population of 1259000 (statistics at the end of 2016).
　　
2、 Analysis of current situation and problems

The contradiction between supply and demand of water resources is becoming increasingly serious, the utilization rate of unconventional water resources is low, and the reclaimed water volume needs to be improved; some rivers and lakes have eutrophication of water bodies, and the non-point source pollution of runoff has not been effectively controlled; the water ecosystem has degenerated, and the ecological shoreline of rivers and lakes is weak; the rainwater drainage system is imperfect, and there are hidden dangers of water logging, and the risk management system needs to be improved.

　　
3、 General planning

Planning principles: Based on ecology and following nature; guided and promoted by planning; adjusted measures to local conditions and overall layout; guided by government and participated by the public.
Planning objectives: fully implement the concept of sponge city construction and development, promote the construction of sponge city in the whole region as a whole, and realize the efficient utilization of water resources, improvement of water environment, good water ecology and water security.
Planning scope: Xicheng District, 50.7km2.
Planning period: short term: 2020, long term: 2030 and beyond.
Overall planning idea: macro (natural ecological spatial pattern interwoven with blue and green) meso (protection of water space, treatment of water environment, restoration of water ecology, guarantee of water security) micro (comprehensive promotion of low impact development and construction)

4、 Sponge system planning
　　
Water resources system planning: renewable water use (give priority to urban greening, road sprinkling and other municipal miscellaneous uses, increase the supply of renewable water to main rivers and lakes, take into account the construction and industrial water, and effectively use renewable water instead of new water resources.) Water leakage control of rainwater resource utilization (rainwater collection and infiltration) water supply (the leakage rate of public water supply network in Xicheng District is planned to be controlled within 10% in 2020.)
Water environment system planning: water environment treatment project (strengthen the treatment work of key water bodies such as old Gulou Street section of north moat, Taoranting lake, Beibinhe road of Guang'anmen), non-point source pollution control (adopt the whole process treatment countermeasures of source reduction, process control and end treatment of rainwater runoff)
Water ecosystem planning: sponge water system construction (according to the site conditions of the surrounding land, based on the appropriate rainwater utilization, peak flow reduction, total annual runoff control and other rainwater runoff control objectives, the spatial layout and water system connection of low impact development facilities are determined based on the comprehensive low impact development facility type and scale, and the sponge city index is implemented.) . ecological shoreline transformation (according to the design concept of natural ecology, the ecological shoreline transformation shall be carried out for the rivers and flood discharge channels with vertical hardened revetments within the planning scope, so as to play the ecological and landscape functions of the rivers while ensuring the flood control requirements.)
Water safety system planning: the flood control standard of Xicheng District is not less than 200 years.
　　
5、 Sponge city construction guidelines
　　
Guidelines for construction of buildings and communities: new buildings (including reconstruction and expansion) and communities shall strictly comply with the code for design of rainwater control and utilization engineering

Guidelines for road and square construction: runoff and control of non-point source pollution, supplemented by rainwater collection and utilization

Guidelines for park and green space construction: it is mainly based on local infiltration, and should absorb its own rainwater. If possible, it can be used as regional rainwater regulation and storage facilities, which will lead the production flow of surrounding impervious areas (such as roads, buildings and communities) to them for storage and purification.

Guidelines for river and lake water system construction: use the waterfront public green space to set up low impact development facilities with purification function, such as vegetation buffer zone, biological detention facilities, etc., strengthen the governance through various measures, and restore the ecological function of water body.

Guidelines for construction of low impact development facilities: new construction (including reconstruction and expansion) projects shall be strictly reviewed for the construction requirements of sponge city in the approval stage, and the construction requirements of sponge city shall be strictly implemented in the planning, design, construction and operation stages. All kinds of infrastructure such as water supply, rainwater discharge, sewage discharge and renewable water use shall be built in the new area to meet the standard. Various low impact development measures shall be arranged according to local conditions in the construction of plot.
　　
6、 Sponge city construction plan
　　
Recent construction plan
　　
1. Reconstruction project: Based on problem-oriented, combined with shantytown reconstruction, old residential area reconstruction, municipal facilities reconstruction, road large and medium-sized repair, road microcirculation reconstruction, green landscape improvement and other urban construction work, the sponge facilities reconstruction work should be promoted step by step and with emphasis, which is not suitable for large-scale demolition and construction.

2. New project: the problem is combined with the goal orientation, and the goal orientation is the main one. All kinds of urban land, such as buildings and communities, roads and squares, parks and green spaces, fully implement the concept and requirements of sponge city construction. By regulating, storing and purifying the source and the end of the river, we can reduce the pollution of the surface source into the river, improve the ecological environment of the river and lake, focus on rainwater collection and reuse, and reduce the consumption of clear water resources.

Long term construction plan: in 2030, the annual runoff control rate of 80% of the built-up area will reach 72.6%.
　　
7、 Planning connection
　　
In order to implement the requirements of sponge city construction, on the basis of the preparation of special planning for sponge City, it is necessary to continue to further improve the urban planning, implement the relevant requirements in the legal planning, and adjust and optimize the relevant special planning.
　　
8、 Guarantee system of sponge city construction
　　
Organization guarantee, system guarantee, fund guarantee and capacity building