The idea of a sponge city is simple – rather than using concrete to channel away rainwater, you work with nature to absorb, clean and use the water.

“Floods are not enemies,” explains Professor Kongjian Yu. “We can make friends with floods. We can make friends with water.”

What we have done is totally wrong, he says. He returned to China after studying landscape architecture at Harvard University in the US, determined to tackle one of the biggest problems facing cities.

His solution was to work with nature rather than against it.

Natural flow

Eco-friendly terraces allow land and water to meet, explains Kongjian, or “the Sponge Cities Architect” as he’s known.

During the dry season, the terrace is a park for residents to enjoy. But during the rainy season it can flood, protecting the city without the need for grey infrastructure like flood walls or dykes.

Image: Reuters

Not only does this safeguard the city by working with nature, but the water is clean, vegetation can grow and a habitat is created for wildlife.

It’s not just wetlands and restored riverbanks, though. Sponge cities also include green walls and roofs, permeable pavements and green buildings.

Join the Voice for the Planet movement

Voice for the Planet is a global online action campaign calling for action on climate change.

Launched by the World Economic Forum’s Global Shapers Community at Davos in 2019 and in partnership with the Netflix and World Wildlife Fund "Our Planet" series, it encourages people to make commitments to change the way they eat, embrace renewable energy, restore nature in their communities, change what they buy and ask their government leaders to act.

Add your voice here.

All from one city

And it all began in just one Chinese city, 20 years ago.

Today, 250 places in the country are working with Kongjian and his team, as well as urban areas everywhere from the US and Russia to Indonesia.

Image: Reuters

It’s an inherently global answer to a problem that afflicts a variety of places, he believes. “The ecological-based or nature-based solution can be a solution global-wise.”

Read more about the inspiring pioneers finding creative solutions to the climate crisis here: wef.ch/pioneersforourplanet

About the series: Each week we’ll bring you a new video story about the people striving to restore nature and fighting climate change. In collaboration with @WWF and the team behind the Netflix documentary #OurPlanet. #ShareOurPlanet

Want to raise your #VoiceForThePlanet? Life on Earth is under threat, but you can help. People around the world are raising their voice in support of urgent action. Add yours now at www.voicefortheplanet.org