Just 50km outside of Shanghai, the city of Kunshan is bursting with water. With over forty lakes and one thousand kilometres of canals and waterways in total, water defines the urban fabric of this beautiful city, which is home to the most famous ancient water town in China “Zhou Zhuang.”
Due to the city’s low-lying nature, Kunshan has adapted to the risk of frequent inundation through adopting a polder landscape; a low-lying tract of land enclosed by dikes with connection to waterways through gates and pumps.
Climate change will likely increase the fragility of Kunshan in regards to stormwater management within the polder system. In addition, the water quality in the extensive network of constructed canals is degrading due to a combination of catchment pollution, poor circulation and rapid urbanization, even though the vast majority of its wastewater is collected and treated.
The City Water Group centrally manages water supply with 30-40% of local supply from lakes and the rest coming from the Yangtze River, which is obtained at a high energy cost due to pumping.
Kunshan’s overarching strategy is to develop into a sponge city, through managing stormwater pollution at source and harvesting it as a resource for non-potable use to transform the city into a water supply catchment. This concept is coupled with polder-wide recirculation of canal water through precinctscale wetlands nested within open space to maintain the water quality. This city-wide strategy is important, not only to reduce the urban pollution in regional waterways, but also to mitigate flood risks for downstream cities, and to ensure safe water supply in the context of population and urban growth by reducing the level of dependency on external source.
Natural drainage systems in urban areas filter and recycle the water and ensure peak flows are detained and safely conveyed to waterways. This concept is applied at small and large scales, with multifunctional areas combining blue, green and grey infrastructure as integral parts of the urban ecosystem.
Kunshan delivers cross-sectoral government-wide responses, involving the public and private sectors to capture all the opportunities to protect and enhance its canals and waterways, and to progressively transform the city both structurally and institutionally into a water-wise city.
In the Kunshan Culture & Arts precinct, water sensitive design is being implemented through constructed wetlands integrated into the public landscape by a multi-disciplinary project team. The system shows the effectiveness of wetland based recirculation for maintaining clean water, and demonstrates how public open space can provide ecosystem services beyond traditional amenity values in the urban environment.
• Natural drainage systems, wetlands, and green infrastructure
• Stormwater harvesting and reuse & self-contained projects across the city
• Polders as a water supply catchment to reduce the water exporting from Yangtze therefore reducing energy
• Multifunctional urban and public spaces with green infrastructure
• Managing stormwater flows- turning the city into a catchment. Polders in use for many years now.
• Biofilters to reduce peak flow
• Canals and urban water around the city, as well as green infrastructure
• Biofilters to treat elevated highway stormwater runoff to reduce pollution in waterways
• Reuse projects for non-potable use
• New treatment processes and natural drainage to treat the water
• Self-contained stormwater treatment projects
• Mitigate flood risks for downstream cities in the same basin given the uncertainty imposed by future climate change impacts
• Social research to understand community perception and willingness to pay towards green infrastructure
• A strong multi-disciplinary team established with planners architects, landscape designers, ecologists, and engineers
• Transdisciplinary planning teams involving public and private sectors
• Blue, green, and grey corridors created by coordinating planning and implementation between various stakeholders
• A shared Sponge City vision bindin key leaders from urban development, planning, water services and transport to deliver coordinated effort.
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