China proposes to build sponge cities

(ORDO NEWS) — To mitigate the impact of extreme weather conditions caused by climate change, a Chinese landscape architect is proposing that China and other countries build so-called “sponge cities”.

Yu Kongjian presented his vision of cities that can withstand variable temperatures, drought and heavy rainfall.

The challenges of realizing this vision at a time of ambitious economic development in China are manifold.

Yu criticizes much of Asia’s modern infrastructure for being built on ideas imported from Europe, which he says are ill-suited to the monsoonal climate in much of the Asian continent.

He points to the recent floods that have wreaked havoc in many Asian cities, which he says are caused by this architectural mismatch.

“There’s no sustainability at all,” Yu says of the concrete and steel infrastructure of large cities and the use of pipes and channels to drain water.

“It’s useless, they will fail and continue to fail.”

Instead, Yu proposes to use natural resources to create water-resistant cities. By creating large water storage spaces in urban centers such as parks and ponds, stormwater can be held in place, helping to prevent flooding, he says.

Spongy infrastructure also, in theory, offers ways for water to seep and recharge groundwater during times of drought.

A decade ago, China saw a turning point in climate change awareness and urban adaptation, Yu said. In July 2012, a devastating flood hit the capital, Beijing.

The worst rainstorm in Beijing in 61 years destroyed drainage systems, flooded underpasses in the city center and caused flash floods on the outskirts of the city. At least 77 people died.

Yu at the time sent a letter to Beijing Party Secretary Guo Jinlong, calling for a change in the government’s approach to urban infrastructure.

He continued to send letters to senior officials and senior leaders, including Chinese leader Xi Jinping.

At a government work conference the following year, China incorporated the idea of ​​sponge cities as a national strategy, “emphasizing the absorption, storage and slow release of rainwater by ecological systems.”

In 2014, the central government issued a directive to recycle 70 percent of rainwater in 20 percent of urban areas by 2020 and 80 percent of urban areas by 2030.

It launched 16 sponge cities pilot projects the following year, adding 14 more in 2016. Officials also said they will allocate 600 million yuan each year for three years to municipal cities, 500 million yuan to provincial capitals, and 400 million yuan to other cities.

The top-down mandate and subsidies have sparked a boom in water-absorbing infrastructure, including in major cities including Beijing, Shanghai and Shenzhen.

Cities around the world are similarly trying to integrate “biogold” along roadsides, protect remaining wetlands to absorb water, and increase rooftop rainwater harvesting.

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Residents relax in the Sponge Fishtail Park, which was built on the site of a former coal ash dump in Nanchang

In China, one demonstration park is located in the northeastern part of the city of Nanchang in the south of the country. In mid-October, engineers were putting the finishing touches on a lush, scenic 126-acre park designed to mitigate the effects of floods and droughts.

The Fishtail Sponge Park, a former coal ash burial site, is built in a low-lying part of the city and is designed to regulate the water supply of nearby areas and business districts.

Fly ash, a by-product of burning coal, has been mixed with soil to create mini-islands in the lake that allow water to pass through. Fang said the mixture, held in place by plant roots, prevents ash from entering the water.

During dry periods, water can be withdrawn, purified and used to irrigate plants.

Fang Yuan, an engineer at the Yu Design Institute, Turenscape, said the park serves as an “ecological aquarium” capable of holding 1 million cubic meters of water during floods, meaning the water can be used instead of just dumped down the drain.

The park also serves as a habitat for plants and wildlife affected by extreme weather conditions such as drought.

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