Sponge Cities

Nov. 22, 2017

You may have read recently about China’s “sponge cities.” They’re an approach to what we commonly call green infrastructure—an attempt to reduce flooding and infiltrate stormwater runoff in some of the areas most affected by rapid urbanization. China has spent $12 billion so far—with federal and local governments and private developers all contributing—in about 30 different cities to install measures such as permeable pavements, bioswales, green roofs, and wetlands.

Flooding has become a deadly problem in China, especially in major cities. As this Economist article notes, the country’s urban land has more than doubled in the last 20 years, and cities sometimes expand right into the floodplains. “All this is exacerbated by China’s often impetuous approach to urban planning,” the article continues. “When the planners in charge of Beijing designed its roads a few decades ago, for example, sunken underpasses were chosen over elevated interchanges for the reason that they seemed more appealing visually, as well as being cheaper to build. They have also, as it turns out, become a particular source of sodden misery. Beijing has 149 such underpasses in its urban districts. With inadequate drains and pumps, even a single heavy rain can turn them into swimming pools, bringing traffic to a halt in the process.”

There are some differences between the way that China and the US are putting green infrastructure in place. For one, some of China’s sponge cities—Lingang near Shanghai, for example—are planned cities, and the various measures such as permeable road surfaces and green roofs are being put in pretty much all at once, rather than in piecemeal retrofit projects.

For another, it seems China has an ambitious goal not just to remove runoff but also to put it to use. “By 2020, China hopes that 80% of its urban areas will absorb and re-use at least 70% of rainwater,” this article states, although it’s not clear exactly how the water will be stored for further use or for what purposes—such as irrigation, cooling, or toilet flushing—it might be used.

It’s an impressive effort for a country that has so recently been criticized for water-related projects like the Three Gorges Dam, which displaced more than one million people and had serious environmental repercussions. It’s tempting to think that this new approach to flood control might be part of a larger environmental movement. Arturo Santiago, editor of MSW Management magazine, has written extensively about China’s upcoming ban on accepting waste from abroad (you can see a webcast with more information on the ban here). It will have a big effect in the US, as much of what we currently recycle—paper, plastic, metal, and more—is shipped to China for processing. “Why now?” he writes. “There is a huge environmental problem in China (which is not breaking news), but China has been going from one industry to the next in trying to clean up those industries, and recycling is one of them. It’s been discovered that the problems are not with the inbound shipments; this is actually an attempt to clean up China’s domestic recycling industry.”

You can read more about sponge cities here, including the funding challenges and prospects for public-private partnerships to make them feasible.

StormCon 2018 Call for Papers Is Open

StormCon, the conference exclusively for stormwater and surface-water professionals, is seeking abstracts for presentation at StormCon 2018, which will take place in Denver on August 12 – 16, 2018. The deadline for submitting abstracts is Wednesday, December 6, 2017.

We are accepting abstracts in six conference tracks: Stormwater Infrastructure and Best Management Practices; Green Infrastructure; Stormwater Permit Compliance; Funding, Staffing, and Managing the Stormwater Program; Industrial Stormwater Management; and Research and Testing. For descriptions of the tracks and more information about submitting an abstract, please visit www.StormCon.com

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.