Chongqing- The General Office of China's State Council issued guiding opinions on the promotion of sponge city construction in 2015, which required the measures of infiltration, stagnation, storage, purification, utilization, and drainage to minimize the impact of urban development on the ecological environment.
Beginning that year, the Ministry of Housing and Urban-Rural Development launched two batches of pilot projects to construct 30 sponge cities. As one of the first batch of 16 pilot cities, Chongqing has actively explored and achieved preliminary results by first initiating the pilot, followed by gradual promotion and general application.
As the 13th Five-Year Plan drew to a close, Chongqing Municipality had completed 281 drainage zones that met the requirements of sponge city construction, covering a total area of 421 square kilometers and representing 24.2% of built-up areas.
This meant the goal stipulated in the 'Phased Assessment Tasks for 2020,' of reaching over 20% of built-up areas had been successfully attained. As a result, Chongqing has made the concept of sponge cities a reality after having begun the project completely from scratch.
New that requirements call for the systematic and wholesale construction of sponge cities through combining urban flood control, drainage facilities, underground spaces, and the renovation of old residential communities, the level of practical application in Chongqing means that sponge cities can be further promoted from mere reality to the realm of high quality.
Construction of water-related projects
The promotion of water-related engineering systems can protect the ecological resources of mountains, rivers, forests, countryside, lakes, grassland, and desert. They can also ensure water safety through drainage that prevents waterlogging, improve the water environment through systematic regulation of river basins, encourage unconventional water recycling practices, and concentrate existing water resources.
Looking to the future, sponge city construction should be strictly implemented in new urban developments through management and controls, while the renovation of old communities should also be orientated towards this objective so that development, in general, can progress in a coordinated manner.
Natural water system resources can be integrated with open public areas in Chongqing's more level urban areas, while new sponge city measures such as permeable ground materials control issues like waterlogging. (iChongqing file photo)
Differentiated approaches
As Chongqing has a complicated geographical mix of mountains and rivers, the strategies implemented in sponge city construction need to be adapted for specific terrains. For example, three-dimensional construction methods should be adopted in hilly areas that follow the principles of soil consolidation, water interception, overfall energy dissipation, low-level usage of high water, and bottom-level confluence.
Technical measures should be adopted in the construction of buildings and community areas, while careful analysis should be performed on the micro terrain to meet the functional needs of residents. Coordinated development between landscapes and sponge city design should also be taken into accounts, such as the use of permeable ground slabs in roads and public squares, while more green spaces should be developed on roadsides and central reservations to control runoff and pollution.