By Vianna Singh and Jingyi Zhao
The story of Dayuzhishui (Dayu controlling water) tells the tale of a Chinese ancient hero, who used his wisdom to control massive floods and saved the Chinese nation from disaster. Although this story dates back several millennia, Dayu doesn’t disappear in China. Kunshan, with sponge city construction (SCC), becomes Dayu, controlling water and protecting Shanghai.
Located just upstream of Shanghai, Kunshan once sent floods rushing down to Shanghai whenever heavy rain came. Climate change has intensified these heavy rains, and with the frequency of heavy precipitation days rising across China, researchers project a further 16.5% increase in summer monsoon rainfall. SCC combats these flood waters. It’s a simple yet powerful concept, utilizing green infrastructure to turn the city into a kind of sponge. This nature base solution alters the landscape itself, adding parks, wetlands, green roofs (rooftops covered with vegetation), and permeable streets (pavements designed so that water can pass through them). These alterations allow water to be absorbed, stored, and then slowly released when needed, turning Kunshan into a hero, shielding Shanghai.
In 2022, the central government selected Kunshan as one of 25 demonstration cities to promote sponge city practices throughout China. Kunshan’s story highlights why, in these times of climate change intensified weather, more cities and individuals should invest in SCC, embracing green infrastructure in their communities and homes. This can be as simple as adding vegetation to your yard!
SCC goes well beyond flood protection. This adaptation solution has carbon emission mitigating effects. Duke Kunshan University Professor, Dr. Gu, explained how the added vegetation absorbs negative carbon emissions from the atmosphere through photosynthesis. This is also done through carbon sinks caused by the added wetlands. Additionally, the added greenery incorporated into the urban environment cools the city, countering the heat island effect, creating a safer climate for Kunshan residents.
Water Culture in Kunshan
This sponge city project incorporates more than just engineering. Kunshan is part of Jiangnan, a region that has long been defined by its canals and rivers. Water here is not just a necessity, it’s tied to the local culture and identity. Local people hold deep feelings towards water, and SCC builds on that connection. In blending modern innovation with centuries old water culture, Kunshan illustrates how cities can hold tradition while adapting to changing climate. To learn more about how this vision came to life and the impact of sponge city, we spoke with Director Xi from Kunshan’s local government and Dr.Gu.
Interview with Director Xi
Q: Have ancient Chinese water systems influenced the construction of Kunshan’s systems?
A: “Water culture” is an important factor of Kunshan’s sponge city. As a part of China’s water towns, Kunshan’s people have special emotions towards water. Ancient poetry also described the beauty of water in Kunshan, making water a part of Kunshan’s culture. Kunqu, a famous art form originating from Kunshan, also has a name: Shuimodiao, which means tongue polished by water. Kunshan’s citizens support the sponge city infrastructure investments in part because of their historical water culture.
Director Xi
Q: Why does Kunshan need sponge city construction?
A: Apart from the frequent rainfall caused by climate change, which causes flooding, Kunshan also faces water shortage caused by water pollution. Stormwater runoff leads pollution on the road into streams and lakes. Fortunately, that’s what sponge city can help with. In addition to this, Kunshan acts as a dam to stop Tai lake’s floodwater from inundating Shanghai.
Dr. Gu
Q: How has Kunshan’s sponge city construction been effective in lowering heat islands?
It helps a lot, one way sponge city construction “cools down the temperature by a process called evapotranspiration, this way the trees, plants, and other vegetation absorb the heat from the environment and reduce the sensible heat (feel like temperature).” Tree canopies also do this by providing shade. Another way this is done is through water heat retention. Water, compared to soil and concrete, can store enormous amounts of heat “cooling down the temperature in the surrounding environment.”
Dr. Gu
Q: How has sponge city construction improved Kunshan’s biodiversity?
A: Sponge city structures support a much greater biodiversity. The added “vegetated landscapes provide habitats for many organisms. Wetland systems provide a variety of microhabitats for aquatic life and land life.” Different wildlife’s require different ecological niches, they require certain food, need to live within specific environmental conditions, require certain temperature and moisture conditions, excreta. “The more complex the landscape is the more wildlife it attracts and can host.”
Director Xi
Q: How have Kunshan residents seen the effects of sponge city construction in their lives?
A: The improvements in life quality are significant. When it rains, your shoes will not get wet. To absorb water, there are more rain gardens and trees in communities, improving the community’s environment. By purifying water, water quality in rivers and lakes improved.
This blog was written as part of the PUBPOL111 course Communicating Climate Solutions: Writing for Impact taught by Professor Jennifer Turner.
