Sponge City Development in China
The nationwide implementation of the sponge city concept in China since 2014 is being followed with worldwide attention. Initially, pilot measures for sponge city development were implemented in 30 cities in all parts of the country, of which the first 16 locations are currently under evaluation. On the basis of the findings soon available, 20% of the built-up urban areas in China are to be developed as sponge cities by 2020 and 80% by 2030.
Thus, the concept of the sponge city has become one of the central planning variables in urban development in China. A new green and blue infrastructure has taken priority on the urban surface to provide a convincing response to urban flash floods caused by heavy rainfall events. Rainwater is not only to be stored, but also used as a new water resource for urban water needs. In this way, there are still issues to be solved, such as how the pollution of precipitation/urban run-off can be removed, Thus, how to deal with plollution of urban run-off with tyre abrasion, fine and often particularly polluted particles as well as pathogens before rainwater is ready to be used in urban contextes.
The Beijing city government moves to the Tongzhou district. This was the reason to pilot the concept of the sponge city there - and with KEYS now also with German contribution. The key elements of the three-year project are the demonstrations. The KEYS network with 17 partners from Germany and China is working on optimizing existing sewer systems with regard to material retention, integrating retention soil filter technologies, introducing new sponge city elements, implementing mobile concepts for recording measurement data in urban catchment areas and further developing wastewater treatment not only with regard to the emerging pollutants.
In the context of urban transformation, the concept of sponge urban development will have to be proven especially in existing urban neighbourhoods. To do this, an exchange of data and experience should take place on suitable platforms, covering both aspects of the operation and maintenance of the facilities. In order to ensure the long-term functional maintenance of the sponge city infrastructure, a reliable determination of responsibilities as well as the availability of adequate financial resources for the plant operators is required. With a view to the future, numerous further positive impulses for a city worth living in can be expected from the development of Sponge City, as there are many points of contact to other urban trends such as Urban Gardening, Urban Agriculture and Green Facades/Green Architecture.