The Economist explains: Why are Chinese cities flooding?

Note to Reader:

In 2013, President Xi Jinping injected a new term into the global urban design vocabulary when he proclaimed that cities should “act like sponges” and launched China’s Sponge City program.

Why China Wants to Build Something Called ‘Sponge Cities’

“You may have read recently about China’s ‘sponge cities’.” wrote Janice Kasperson in her Editor’s Blog for Stormwater Magazine.

“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.”

Record-breaking rain caused major flooding in parts of Guangdong Province

The Economist explains: Why are Chinese cities flooding?

“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.”

Flooded area in Liuzhou, Guangxi province, China, July 2, 2017. Picture taken July 2, 2017.

Contrasting Approaches to Green Infrastructure

“There are some differences between the way that China and the US are putting green infrastructure in place,” continued Janice Kasperson.

“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.

“Changgou Masterplan”, a 3.8 sq km project located in Beijing’s Fangshan district.

To Learn More:

Download a copy of Why are Chinese cities flooding? to read the complete story published in the Economist in November 2017.

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

Download a copy of Sponge Cities: An Answer To Floods, written by Yuanchao Xu in May 2016.