Shenzhen has designated 27 key areas to pilot its Sponge City program, according to an implementation plan released on the official website of the Shenzhen Municipal Planning and Natural Resources Bureau recently.
The pilot areas will implement a low-impact concept to retain, filter and store rainwater through new construction projects, roads, green areas and a drainage system to minimize the impact of urban development on the ecological environment.
The areas include the Greater Airport Area, Bao’an CBD, Qianhai Cooperation Zone and Universiade New Town in Longgang District.
The program covers a total area of 312.7 square kilometers, including 235 square kilometers of land for industrial use, taking up 24.1 percent of the urban built-up area.
The 1.2-km Dengliang Road in Nanshan CBD became the city’s first permeable road when it was put into use last August.
Though it looks no different from an ordinary two-way four-lane urban road, the secret lies in its permeable road surface and roadside rainwater gardens.
According to the Shenzhen Municipal Public Works Bureau, to construct permeable vehicle and pedestrian pathways, pervious concrete is placed over layers of pebbles and soil. This allows the infiltration of fluids such as rainwater.
The rainwater filtered through the permeable surface can run into the roadside greenery belt, which is filled with plants that naturally collect and filter rainwater. The roadside greenery belts are part of the rainwater garden, where the grass, bushes and silkwood can absorb and reserve rainwater. That water is then allowed to seep into the soil to replenish the groundwater.
In heavy rain, the excessive water that the rainwater garden can’t absorb can run into the city’s water drainage system.
The significance of the permeable road is that it can reduce the risk of flooding and avoid the waste of rainwater, according to the bureau.
The public works bureau is undertaking 25 projects under the Sponge City program, including 14 construction projects, four park projects and four urban road projects.
The city government has laid out a plan to expand the Sponge City areas and carry out 150 renovation projects to upgrade existing facilities in order to meet the requirements of a Sponge City.
Shenzhen was chosen by the Central Government as one of the 16 cities to pilot the national Sponge City program in 2016.
China launched the Sponge City program at the end of 2014, aiming to design and construct city infrastructure that can absorb and capture rainwater for reuse.
The Sponge City in Shenzhen will be able to collect and reuse 70 percent of the rainwater. According to the city’s plan, over 20 percent of urban areas in Shenzhen will be turned into Sponge City areas by 2020, while 80 percent of urban areas will reach the goal by 2030.