Conventional wisdom regarding stormwater mitigation dictates that developers prioritize so-called gray infrastructure – concrete and steel construction that works to reroute flooding in order to minimize loss of life and property. But what renowned landscape architect Kongjian Yu has insisted for years now is that nature itself actually has many of the answers we seek in regard to flood preparedness.
For Yu and his Beijing-based firm Turenscape, a sustainable future lies in the creation of (and conversion to) “sponge cities” – urban landscapes that eschew harsher materials in favor of softer, natural ones that can absorb, better utilize, and repurpose water.
Waterfront Alliance is honored to host Yu as our annual Heather M. Morgan Climate Risk Adaptation Lecture Series speaker at next month’s Waterfront Conference, as his brilliant innovations in urban landscapes directly align with the Waterfront Alliance conception of resiliency.
Climate strategies focus primarily on carbon, largely ignoring the water cycle that humans have destabilized, increasing water disasters and accelerating climate change. Sponge projects can reverse its degradation.
Soak It In
After graduating from Harvard Graduate School of Design in 1995 with a Doctor of Design Degree, Yu spent two years planning and designing landscapes stateside before returning to China where, in addition to his work with Turenscape, he currently serves as Professor and Dean of the College of Architecture and Landscape Design at Peking University. Turenscape has planned over 10,000 sponge city projects in more than 250 international cities since circa 2010.
The key aim of a sponge city is to cultivate permeable landscapes that soak up and retain stormwater, then release it back into the environment in a nourishing and productive way. Yu argues that not only is this less expensive than concrete- or pipe-based solutions, but the inflexibility of the latter can actually result in increased flood damage, due to blockages and overflows, a la a hardened artery.
An initial example of Yu’s ingenuity was his Yanweizhou Park project, in the city of Jinhua. The annual rainfall there had become simply too much for the existing floodwall to bear. But instead of simply fortifying and raising that floodwall – a fix that might require repetition in perpetuity – Yu removed it entirely from the riverbank, opting to instead plant natural grass, willows, and reeds, along with installing overflow ponds and a permeable footpath. This organic solution was not only successful in its initial intent, but it provided the park with an objective aesthetic upgrade.
After a series of similar successes from the Turenscape team, a sponge city program was formally inaugurated by Chinese President Xi Jinping in 2013. An initial slate of pilot projects in 16 Chinese cities has since blossomed to over 640 sites across the country.
Scaling Up
The long-term goal of the sponge city initiative is to urge international municipalities to embrace natural alternatives to the large-scale – and costly – infrastructure solutions frequently preferred by governments and major construction corporations alike.
Each sponge city would be tailored to its specific location, weighing local topography, viability of assorted wildlife, and weather patterns in its design, in addition to what each respective community actually needs and wants in their backyards.
In China, the aspiration is to have 70% of rainfall during extreme weather events be successfully absorbed within sponge cities by 2030.
Of course, the sponge city concept is not an infallible one. In 2023, Beijing fell victim to serious flooding after being inundated with heavy rainfall which wiped out wetland parks that were specifically designed for their absorption capacity. Critics worried that densely populated urban centers like Manhattan are simply not readily convertible via the sponge strategy, as it would require the installation of multiple Central Park-style natural enclaves on a crowded island. (Note that Beijing is not a formal sponge city yet, though many cities brand themselves as such. What happened in Beijing is what the concept of sponge cities intends to resolve.)
But where land is not abundant to be developed, Yu advocates for the replacement of existing concrete and asphalt with permeable pavement. The implementation of green roofs and the installation of bioswales – basically a vegetated trench that can divert stormwater runoff – can also have significant mitigating effects.
The value-add of a sponge city is not solely preventative; this approach to landscape design has been shown to reduce temperatures and help with water shortages. Plus, the uptick in park development simply required by the very sponge city concept provides abundant free and accessible amenities for all city residents.
As Yu frequently phrases it, for too long we have been boxing with nature – viewing it as a beast to be battled. To embrace the sponge city concept is to simply redirect its energy – it’s design as tai chi.
Beyond that in his and his co-authors’ article on Nature Water, “To Solve Climate Change, We Need to Restore Our Sponge Planet” (1) commented that: “Climate strategies focus primarily on carbon, largely ignoring the water cycle that humans have destabilized, increasing water disasters and accelerating climate change. Sponge projects can reverse its degradation.” They empower people to collaborate with their neighbors and water to make their own communities more resilient. Family by family, community by community, the success of their local projects inspires others, and piece by distributed piece, we can restore a Sponge Planet.
Run Don’t Walk
Yu has often been lauded for his pioneering work over the years, including being awarded the $100,000 Oberlander Prize from the Cultural Landscape Foundation in 2023. He has written over 20 books and 300 papers pertaining to landscape architecture and urbanism and serves as chief editor of the journal Landscape Architecture Frontiers.
Next month, Yu will pull double-duty at the Waterfront Conference, providing the Heather M. Morgan Climate Risk Adaptation Lecture and appearing in an open dialog with architects, engineers, and students, moderated by Lauren Micir of AECOM.
Waterfront Alliance is truly privileged to present this opportunity to engage with a one-of-a-kind thinker in the resilient design space.
Footnotes:
- (Yu, K., Gies, E. & Wood, W.W. To solve climate change, we need to restore our Sponge Planet. Nat Water 3, 4–6 (2025). https://doi.org/10.1038/s44221-024-00355-x)
