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The man who wants to turn cities into “sponges” to deal with floods

The man who wants to turn cities into “sponges” to deal with floods

He argues that building on higher ground and allocating floodplains, for example, is cheaper than building a system of pipes and tanks.

Yu Kongjian remembers the day he nearly died in the river.

The White Sand Creek, swollen by the rain, had flooded the rice terraces in the Yu agricultural commune in China.

Yu, only 10 years old, ran excitedly towards the shore. Suddenly, the ground beneath his feet collapsed, dragging him into the waters in a terrifying instant.

But the banks of willows and reeds slowed the flow of the river, allowing Yu to grab hold of the vegetation and get out.

“I’m sure that If the river was as it is today, smoothed out with anti-flood concrete walls, I would have drowned”He tells the BBC.

It was a watershed moment that would affect not only his life, but the rest of China as well.

Yu Kongjian, uno de los China’s leading urban design thinkers and dean of the prestigious Faculty of Architecture and Landscape at Peking University, is the man behind the concept of sponge cities that are being developed in various parts of the country to manage the floods.

It’s an idea that he says other places could embrace, even though there are those who question whether the concept of sponge cities could really work to tackle the most extreme floods linked to climate change.

“Don’t fight the water ‘”

What if a flood was something we accept rather than fear?

This is the central idea behind Professor Yu’s Sponge City.

The conventional way of managing floods is build pipes or drains to carry the water as quickly as possible, or reinforce river banks with concrete to ensure they do not overflow.

But a sponge city does the opposite, instead seeking to absorb rain and slow surface runoff.

Try to do it in three areas. The first is at the fountain, where like a sponge with many holes, a city tries to contain the water with many ponds.

The second is through flow, where instead of trying to channel water quickly in straight lines, meandering rivers with vegetation or wetlands slow down the water, as in the stream that saved your life.

This has the added benefit of creating green spaces, parks, and animal habitats, as well as purifying surface runoff with plants that remove polluting toxins and nutrients.

The third area is the sink, where the water flows into a river, lake, or sea.

Professor Yu advocates giving up this land and avoiding construction in low-lying areas. “You can’t fight water, you have to let it go”, dice.

Although similar concepts exist elsewhere, the sponge city stands out for use natural processes to solve the city’s problems, says sustainable design expert Dr. Nirmal Kishnani of the National University of Singapore.

“Right now we have a disconnect … but the idea is that we have to find our way back to see ourselves as part of nature”.

Much of the concept is influenced by ancient agricultural techniques that Professor Yu learned growing up in the eastern coastal province of Zhejiang, how to store rainwater in ponds for crops.

This has won Yu and his landscaping company, Turenscape, many awards.

“Nobody drowned, not even in the monsoon season. We just lived with water. We adapted to the water when the floods came, ”he says.

He went to Beijing at the age of 17, where he studied landscaping and later studied design at Harvard University in the United States.

When he returned to his homeland in 1997, China was in the midst of the construction frenzy that we still see today.

Dismayed by the “gray and lifeless infrastructure”, Professor Yu began to promote an urban design philosophy based on traditional chinese concepts.

In addition to sponge cities, he advocates, for example, a natural rustic landscaping or a “big foot revolution”, as opposed to overgrown parks that he compares to the old-fashioned Chinese practice of bandaging women’s feet to make them look bigger. little ones.

He believes that China’s coastal cities and other places with a similar climate have adopted an unsustainable model to build.

“The technique that evolved in European countries cannot be adapted to the monsoon climate. These cities fail because have been colonized by western culture and copy its infrastructure and urban model ”, he says.

He initially faced opposition from the establishment, some of whom were upset by his vocal criticism of Chinese engineering, including national pride projects like the Three Gorges Dam.

This, coupled with his Harvard experience and applause from the West, earned him accusations of being a traitor and a “western spy” that undermines China’s development.

Professor Yu, who considers himself a son of the Cultural Revolution, finds this idea ridiculous.

“I am not a Westerner, I am a Chinese traditionalist,” he laughs. “We have thousands of years of experience, we have the solution that you cannot ignore. We have to follow our Chinese methods. “

He has cunningly appealed to the sense of patriotism of Chinese officials by making lobby by sponge cities, aided by the media coverage that their ideas have received after the catastrophic floods high-profile in Beijing and Wuhan in recent years.

It was worth it. In 2015, after gaining the endorsement of President Xi Jinping, the government announced a multi-million dollar plan and an ambitious goal: By 2030, 80% of China’s municipal areas should have elements of a sponge city and recycle at least 70% of it. the rains.

A magic bullet?

Around the world, more and more places are struggling to cope with more extreme rainfall, a phenomenon that scientists have linked to climate change.

As temperatures rise with global warming, more moisture evaporates into the atmosphere, causing heavier rains.

And they say that will get worse: in the future, the rains will be more intense and severe than expected.

But with stronger storms Will sponge cities really be the answer?

Some experts are not sure. “Sponge cities may only be good for light or small storms, but with the extreme weather we are seeing now, we still need to combine it with infrastructure like sewers, pipes and tanks,” says flood management expert Faith Chan of the Nottingham Ningbo University, in China.

He also notes that for many dense cities where space is expensive, it can be difficult to implement some of the ideas of Yu, how to provide land for the floodplains.

Despite spending millions of yuan, China still suffers from catastrophic floods.

Last summer, a series of floods caused the death of 397 people, affected 14.3 million and generated economic losses of US $ 21.8 billion, according to estimates by the United Nations (UN).

But Professor Yu insists that ancient chinese wisdom can’t be wrong, and that these failures are due to local officials having implemented their idea inadequately or piecemeal.

The Zhengzhou flood earlier this year, he says, was a classic example. The city had paved over its ponds, so not enough water was held upriver when the rain started.

The main river was channeled into concrete drains, causing the flow of water to accelerate “like a flushing toilet,” he says.

And there were important infrastructures, like hospitals, built on lowlands.

A sponge city could handle any flood; if it doesn’t, it is not a sponge city. It has to be resilient, ”he says.

Another question is whether the concept of the sponge city is really exportable.

Professor Yu says that flood-prone countries like Bangladesh, Malaysia and Indonesia could benefit from the model, and some places like Singapore, the United States and Russia have started to implement similar concepts.

But much of the success of the proliferation of sponge cities in China is possibly due to their centralized government and abundant state coffers.

Professor Yu says that a sponge city would cost only “a quarter” of conventional solutions, if done right.

He argues that building on higher ground and allocating floodplains, for example, is cheaper than building a system of pipes and tanks.

Many of Turenscape’s projects today are aimed at repairing anti-flood infrastructure that cost millions, and this money could have been saved if officials had followed sponge city principles in the first place, he says.

Using concrete to handle a flood is, he says, like “drinking poison to quench your thirst … it’s a myopic vision”.

“We have to change the way we live to adapt to the climate. If they don’t follow my solution, they will fail ”.

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