STEP1 Preliminary data integration
Collect the basic information of the project site and site conditions, and analyze the limiting factors of sponge landscape design. For example, the sponge city indicator control requirements are different due to different land parcel attributes; The regional rainfall conditions determine the rainwater flow and rainwater resource reuse mode; Geological soil and groundwater conditions affect the bottom structure design of specific sponge facilities When the soil permeability coefficient is small, it is necessary to replace the formulated soil to achieve the rapid infiltration effect of rainwater. When the groundwater level is high, rainwater is difficult to infiltrate, so blind pipes need to be set at the bottom for collection and drainage.
The elevation change of the site affects the selection of sponge facilities. Rainwater is difficult to collect when the slope is large, which limits the selection of sponge facilities; The different properties of underlying surface affect the selection and distribution of facilities. When the building occupies a large area, the sponge facilities in the limited affiliated green space can not meet the requirements of rainfall control, and can be combined with gray sponge facilities such as underground water storage tanks or infiltration channels and wells; The site rainwater pipe network system affects the process of rainwater collection in sponge cities. More sponge facilities can be placed in the weak areas of the rainwater pipe network for rainwater collection. After the rainwater is purified by multiple facilities, the clean rainwater after peak shift purification is discharged into the municipal pipe network system, which can enhance the drainage capacity of the municipal rainwater pipe network.
△ Geological soil exploration analysis of the project
△ Project underlying surface analysis of sponge city problems
STEP2 Site survey+meeting
Organize sponge consulting team, water supply and drainage team and landscape team to conduct site investigation, including base investigation and work meeting. With the Owner Verify the basic conditions of the project ， Determine sponge control objectives According to the different conditions of the site, the target positioning of sponge landscape is proposed. Based on the analysis of basic data in the early stage, corresponding sponge landscape design strategies should be proposed to address the restrictive factors and conditions, so as to solve the rainwater problem and bring more unique sponge landscape.
The construction of sponge city should Follow the top-down process To implement the control index of upper planning on site rainwater And design objectives. The design of sponge landscape needs to meet the requirements of national sponge city standards, specifications and atlases, as well as local sponge city guidelines and upper planning requirements. Coordinate the special planning of sponge city construction in the upper city and district, relevant special planning and plot control detailed planning, and meet the design specifications of landscaping to ensure the landscape.
Main standards and specifications include:
Technical Guide for Sponge City Construction - Rainwater System Construction for Low Impact Development;
Technical Code for Comprehensive Utilization of Rainwater in Low Impact Development (SZDB/Z 145-2015);
Technical Code for Rainwater Utilization Engineering SZDB/Z 49-2011;
Water Quality Specification for Reuse of Recycled Water and Rainwater (SZJG 32-2010);
Technical Code for Construction and Community Rainwater Control and Utilization Engineering (GB 50400-2016);
Code for Design of Outdoor Drainage (GB 50014-2006, 2016);
Code for Urban Drainage Engineering Planning (GB 50318-2000);
Evaluation Standard for Green Buildings (GB/T 50378-2014);
Evaluation Standard for Sponge City Construction (GB/T 51345-2018);
Technical Code for Rainwater Gathering, Storage and Utilization Engineering (GB/T 50596-2010);
Code for Urban Water System Planning GB50513-2009 (2016 version);
Technical Specification for Permeable Brick Pavement (CJJ/T 188-2012);
Technical Specification for Pervious Asphalt Pavement (CJJ/T 190-2012);
Code for Design of Urban Road Subgrade CJJ 194-2013.
STEP4 Determination of Sponge City Control Objectives
The control rate of total annual runoff and the removal rate of runoff pollution, as the mandatory conditions for sponge city design, can Query the target range value of local sponge city planning standards The weighted average of sponge targets in each small block meets the index requirements of the upper level large block. Corresponding to different land types, such as residential land, commercial land, public service land, industrial land, etc., the total annual runoff control rate, design rainfall and pollutant removal rate targets corresponding to the project land are obtained.
The property size of each project plot and the surrounding waterlogging situation are different, and the corresponding indicator requirements will be adjusted up and down. The local sponge office can be consulted to determine the specific design indicators. Non mandatory sponge targets, such as concave green space rate, permeable pavement rate, rainwater resource reuse rate and other indicators, should also be determined according to local planning requirements.
Scheme design of STEP5 sponge system
The design of sponge city system should Prioritize catchment zoning Fully respect the topographic and spatial conditions of the landscape scheme, reasonably design the flow direction of surface runoff, divide sub catchment zones and rainwater flow lines according to the layout and vertical relationship of building roofs, roads, green spaces and water systems within the catchment zone. If the rainwater on the front plot of the building generally does not flow to the back of the building, the terrain elevation difference or road segmentation and other reasons are the same, the sub catchment area should be reasonably designed so that the runoff of each plot and road can flow into the surrounding green space or water system in an organized manner, and connect with the rainwater pipe network and overflow drainage system to supplement and enhance the urban rainwater pipe network.
Propose sponge city design strategies according to different underlying surface attributes To build a rainwater flow chart, for example, to deal with roof rainwater runoff, the rainwater from green roofs and ordinary roofs can be disconnected to the surrounding sunken green space, and then simply purified and discharged to the rainwater wetland for further treatment. In the sponge facility process, various sponge facilities with good landscape effect shall be selected and connected in series to form a sponge rain flood management system. Adjust the overall technical idea and landscape layout scheme of the optimal sponge system, and each sponge facility meets the internal control volume requirements of the corresponding sub catchment area.
STEP6 Facility selection and design
The selection and layout of sponge facilities shall Fully consider the use and effect of landscape functions, Take the building community as an example:
Permeable concrete/permeable brick can be selected for hard pavement such as sidewalk square;
It is recommended to use stone to ensure the landscape effect in the main entrance square;
The concave green space in the important landscape axis greening will reduce the landscape quality, and complex sponge facilities such as rainwater garden/biological detention pool can be selected to increase the landscape ecological effect;
High level rainwater flower beds/ecological slope protection/transmission type grass planting ditches can be selected to absorb rainwater and flood in places where high slope slopes are difficult to be concave green spaces;
The roof shall be designed as green as possible. If it can not meet the requirements, the building rainwater riser can be disconnected, and the rainwater will be transferred to the concave sponge facilities around the building for purification and storage. The selection and secondary design of sponge facilities based on different project attributes should focus on the impact on the landscape, and determine the types of sponge facilities and plant collocation.
STEP7 Facility scale verification
Check whether the volume and pollutant removal of all sponge facilities in the sponge scheme meet the control index requirements through sponge calculation sheet (attached) of the volume method formula or SWMM/MIKE/SUSTAIN and other hydraulic model simulation calculation.
Verify whether the sponge facilities in each sub catchment area are distributed reasonably to ensure that the rainwater at each site can be absorbed and stored locally. The sponge facilities in some green spaces are too concentrated, but the amount of rainwater in this area is less, resulting in the double waste of sponge facilities function and economy. Some areas have large rainwater production, and the sponge facilities are not designed properly, which makes it difficult to meet the rainwater control indicators in the corresponding areas, resulting in waterlogging in the corresponding areas. This requires the sponge city design to meet the total amount of indicator control, and the sponge facilities in each internal sub catchment area should also meet the corresponding requirements, so as to achieve a scientifically designed and reasonably distributed sponge city system.
△ Schematic diagram of rainwater simulation software
△ In the sponge city design of Sanya Central Plaza EPA SWMM Software simulation (source: GVL Yijing International Group)
STEP8 Display Design and Benefit Analysis
The concept of sponge city construction should be integrated into urban construction. Through carefully designing the science popularization display system, the concept of "building a beautiful China" and "ecological civilization construction" should be publicized and promoted, and people should be guided to strengthen their awareness of the sponge city, ecological protection and sustainable use. There are many types of display facilities to choose from, including: Sponge rainwater purification streamline display boards, water intakes, water presses or waterscape, etc., form the operation mechanism of display board system node model interactive device cooperation.
The systematic benefits of sponge cities can be reflected in three aspects, namely, ecological benefits, economic benefits and social benefits.
Ecological benefits can control a series of water environment problems such as rainwater waterlogging and pollution To increase ecological diversity, enhance microclimate and reduce heat island effect.
With sustainable economic benefits, the rainwater collected every year can be used for greening irrigation, road washing, waterscape water supplement, etc., reducing daily water cost and operating consumption, and saving a lot of water costs.
In terms of social benefits, the ecological sponge landscape demonstration project has the opportunity to obtain government related sponge city construction cost subsidies and awards. After completion, it can also enhance the added value of surrounding land, enhance the credibility of developers' ecological construction image, strengthen the education of citizens' ecological cultural concepts, and improve the cognition of social low-carbon, environmental protection, sustainable concepts and other values.
△ Qingyuan Puyi Hotel Sponge System Science Popularization Display Board (source: GVL Yijing International Group)
STEP9 Contents of typical sponge landscape design drawings
Mainly: Project overview, project status analysis (location, climate and rainfall, soil, terrain, groundwater, drainage pipe network, etc.), design basis, design objectives and strategies, catchment area and rainwater flow line map, sponge facility general plan, sponge facility elevation map, sponge facility intent map, plant selection intent, calculation and verification, benefit analysis map, etc.
△ Water catchment area map of Shenzhen Guangming Culture and Art Center
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