As climate warms, Chinese planner advocates “spongy cities”

BEIJING (AP) – To cushion the impact of extreme weather conditions due to climate change, a Chinese landscape architect has argued that China and other countries create so-called “spongy cities”.

Yu Kongjian, who spoke to the Associated Press in Beijing, uses broad language to express his vision of cities that can withstand varying temperatures, droughts and heavy rains. The challenges for implementing this vision at a time of ambitious economic development in China are manifold.

Yu criticizes much of modern Asian infrastructure for being built on ideas imported from Europe, which he believes are unsuitable for the monsoon climate of much of the Asian continent. He points to the recent floods that have devastated many Asian cities, which he believes are caused by this architectural discrepancy.

“There is no resilience,” Yu says of the concrete and steel infrastructure of major cities and the use of pipes and canals to channel water. “Those are useless, they will fail and continue to fail.”

Instead, Yu proposes using natural resources, or “green infrastructure” to create water-resistant cities. He is part of a global shift among landscape design and civil engineering professionals to work more in tune with the natural environment. By creating large spaces to hold water in urban centers, such as parks and ponds, rainwater can be held in place, helping prevent flooding, he says. Sponge infrastructure, in theory, also offers ways to filter water and recharge groundwater for dry periods.

“The idea of ​​a sponge city is to recover, to give the water more space,” said Yu.

A turning point in China’s awareness of climate change and urban adaptation came ten years ago, Yu said. A devastating flood hit the capital Beijing in July 2012.

Beijing’s biggest downpour in 61 years has engulfed drainage systems, submerged downtown underpasses and caused flash floods to hit the city’s outskirts. At least 77 people died.

Yu at the time sent a letter to the Beijing party secretary, Guo Jinlong, calling for a change in the way the government deals with the city’s infrastructure. He continued to send letters to high-ranking officials and senior executives, including Chinese leader Xi Jinping.

At a government working conference the following year, China incorporated the idea of ​​sponge cities as a national strategy, “giving full play to the absorption, storage and slow release of rainwater by ecological systems. “.

In 2014, the central government issued a directive: Recycle 70% of run-off rainwater in 20% of urban areas by 2020 and in 80% of such areas by 2030.

The following year, it launched 16 pilot projects for sponge cities, adding another 14 in 2016. Officials also said they would award 600 million yuan ($ 83 million) annually for three years to municipal cities, 500 million. to provincial capitals and 400 million yuan to other cities.

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

Likewise, cities around the world are trying to integrate “bioswales” along the sides of the roads, protect the remaining wetlands to absorb water and increase the capture of rainwater from the roofs.

AN EXPERIMENT IN PROGRESS

In China, a demonstration park is located in the northeast corner of Nanchang city in southern China. In mid-October, engineers were putting the finishing touches on a lush and picturesque 126-acre park designed to cushion the impact of both floods and drought.

A former coal ash dump, the “Fish Tail” sponge park is built in a lower part of the city and intended to regulate the water for the surrounding neighborhoods and business districts. Fly ash, a byproduct of coal burning, was mixed with the soil to create mini-islands in the lake that allow water to permeate. Fang said the mixture, held in place by the plant roots, prevents the ash from flowing into the water.

During periods of drought, water could be withdrawn, purified and used for irrigation of plants.

Fang Yuan, engineer at Yu’s design institute, Turenscape, said the park acts as an “eco-friendly aquarium”, capable of holding 1 million cubic meters of water during floods and means that the water can be used. instead of simply discharging it into the wastewater system.

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

AN UNCERTAIN FUTURE

At times, the sponge city concept has been difficult to implement in China. Incorrect allocation of funds, lack of experience in urban sponge planning and other obstacles have doomed some projects.

In April, the Ministry of Housing and Urban-Rural Development announced that some cities had “insufficient awareness, inaccurate understanding and unsystematic implementation of sponge city construction.”

The notice also warned against using the funds earmarked for the construction of sponge towns for other general infrastructure projects, such as buildings and roads.

The guidelines were issued after heavy rains and catastrophic floods in Zhengzhou city killed 398 people last summer. Floodwater flooded a section of the city’s subway, trapping hundreds of commuters. Rescuers rushed to the scene, but 14 people died in the metro disaster.

In particular, Zhengzhou was one of the sponge pilot cities, with a planned investment of 53.58 billion yuan (7.4 billion US dollars). Some have wondered if the Sponge City projects are working at all.

But a State Council investigation, released in January, found that the funds had been poorly spent. Only 32% of the 19.6 billion yuan invested went to what the government called the “sponge city concept”.

“Even at the critical time when the entire country mobilized forces to support Zhengzhou rescue and disaster relief, they were still” building flower beds, “the State Council report said.

Yu acknowledges that there is an oversight problem. “Many cities only use it as propaganda, just to get a lot of money from the central government,” but then they invest the funds in other projects.

POYANG LAKE

As the implementation problems of absorbent cities are resolved, China’s vulnerability to extreme weather conditions is clear. A prolonged drought since July has drastically reduced China’s largest freshwater lake, Poyang.

In the village of Tangtou, in the northeast corner of the normally water-blessed lake, residents collected buckets of water from a village pond to care for their vegetables.

Since July, the villagers say they have seen hardly any rainfall, let alone the water in their corner of the lake.

“The whole lake was completely dry and the Yangtze River was also dry,” 73-year-old Duan Yunzhen said as he sprinkled the pond water on his crops.

“We planted rice, cotton, sesame and sweet potatoes – they all suffer from drought,” said Hong Zuhua, 62.

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Associated Press video producers Olivia Zhang in Beijing and Wayne Zhang in Nanchang, China contributed to this report.

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The Associated Press’s climate and environmental coverage receives support from several private foundations. Find out more about the AP climate initiative here. The AP is solely responsible for all content.

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