Three Ways to Think Like a Sponge City:

Climate change is real, regardless of whether we agree on the cause. Forward-thinking urban regions are beginning to realize that the effects of climate change are going to be felt, at least to some extent, no matter what actions we take now. The future, if we plan to be there, must be sustainable. So what does that look like where stormwater is concerned? One of the most innovative trends in the industry is the sponge city concept.

First of all: What’s a Sponge City?

Sponge Cities are, as their name suggests, designed to soak up as much extra water as possible. These areas are designed, or in many cases redesigned, to use a combination of storage tunnels, permeable pavements, rain gardens, constructed ponds and wetlands to store as much water as possible. These features not only serve as storage to prevent flooding, but also to serve as a source of water for re-use during times of drought.

Like we’re all wont to think when something new comes along, “What have they got that we don’t have?” Glad you asked! Today we’ll take a look at three concepts sponge cities apply that you might just be able to snag for your city 😊

1. They work with nature, not against it

Much of modern engineering, especially when it comes to stormwater control, is motivated by “taming nature.”  While original stormwater systems were designed to quickly convey waters away from streets and buildings, sponge city systems do exactly the opposite. Instead, they seek to soak in as much water as possible. For example, Rummelsburg, a neighborhood in Berlin, Germany, designed systems using  a combination of green roofs, swales, and rain gardens that provide so much storage that they eliminated the need to construct additional stormwater pipes.

Video: Sponge City, Berlin, Germany

Another part of working with nature is viewing stormwater for the asset that it is (free water!) rather than a nuisance to be rid of. The most stunning example of this concept is the Rain Vortex feature at Singapore’s Jewel Changi Airport. The vortex collects rain from a “bagel-shaped” roof at a rate of 10,000 gallons per minute. The rainwater falls down as a magical-looking waterfall into an indoor garden. The water is used to cool the building and is also re-used within the building. Amazing! And just think— traditional engineering would have funneled all this water onto parking lots and streets to pick up pollution before flowing, dirty as can be, into the nearest stream.


Rain tower at the Jewel Changi Airport (Image Source)

2. They tackle stormwater in a holistic way

In traditional stormwater management, we think of a project here and a bioswale there, but we rarely pull together a vision or plan for our city as a whole. This is what sponge cities do best! The theme of stormwater management “flows” (ha!) thorough all development activities. The city of Wuhan, China serves as a great example of a modern sponge city. Wuhan, which is located along the Yangtze river, experienced massive flooding in 2016 that served as a wake-up call to deal with stormwater and flooding differently. As part of the sponge city initiative, Wuhan seeks to integrate stormwater management into the city design as a whole.  Wuhan has taken storage standards typically assessed on a parcel-by-parcel basis and applied them to the entire city—the goal is to have the city retain 70% of all stormwater by 2020.  For example, Xinyuexie Park, which winds through Wuhan, has been transformed from a dirty drainage ditch to a beautiful green space filled with rain gardens, permeable pavements, and storage ponds for stormwater that will then be reused throughout the city.

Xinyuexie Park, Whuan, China (Image Source)

3. They try new things

Much like the environments in which they are constructed, cities themselves are ever-changing systems. Regions that have adopted the sponge city concept are among the first to realize that the traditional ways of doing things are not always the best. As the city grows and changes, so must the management strategies applied. Thus, sponge cities act as a “test-lab” of sorts for new stormwater management strategies and technologies. Technologies pioneered in sponge cities include multi-scale permeable pavement systems, underground rainwater storage systems for drought-prone areas, and intricate plumbing systems that reuse rainwater throughout urban buildings for non-potable uses. These regions also recognize the importance of data for driving the success of their many innovative systems, thus they’ve been among the first to adapt wide-spread use of monitoring systems to aid in real-time data analysis, visualization, and decision making.

Permeable sidewalk/park space in Kunshan, China (Image Source)

Ready to Get Started?

Step one, change your mindset! Older tropes often speak of engineers declaring a “war on water”. Leading sponge city architect Kongjian Yu  turns this concept on its head by claiming we need to “make friends with water.”

“We don’t use concrete or hard engineering, we use terraces, learned from ancient peasantry wisdom. We irrigate. Then the city will be floodable and will survive during the flood. We can remove concrete and make a water protection system a living system.”

Are you ready to start incorporating concepts of sponge cities into your community? This paradigm shift will not happen overnight, but beginning to apply these concepts to your work will be a step in the right direction. And if you’re curious about incorporating real-time monitoring to get you started, send us a message!

About the author

Suzie Housely

Talk stormwater with Suzie has over a decade of experience in the Stormwater industry including both government and academic work. She leans on her experience to meaningfully interpret scientific studies and government policies to communicate a practical message. Suzie lives just outside Nashville, TN and gets outside whenever she can to explore nature with her husband and two small children.