Can "sponge cities" help protect us from flooding?

Engineers across the globe, from China to East Africa and the US, are turning to a new, nature-based solutions to fight floods, which are becoming more likely in many places because of climate change. They’re taking a pickaxe to asphalt and concrete and instead are restoring wetlands, parks and riverbanks, turning our metropolises into so-called "sponge cities". Plants, trees and lakes act just like a sponge, mopping up rainwater instead of letting it pool and eventually flood our homes.

In a programme first broadcast in 2024, Professor Priti Parikh tells Jordan Dunbar how these spongey solutions have many benefits beyond flooding, encouraging biodiversity, helping our mental health and storing the planet warming gas, carbon dioxide. The BBC’s China Correspondent, Laura Bicker, meets the man who came up with the concept, Professor Kongjian Yu, and visits Zhengzhou, a sponge city in the making. And Katya Reyna tells Jordan how her NGO is helping low-income communities in Portland in the US to ‘depave’ disused car parks, turning them into plant-oases.

Professor Yu died in a plane accident in Brazil in September 2025 while working on a documentary about "sponge cities".

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Contributors:
Priti Parikh, Professor of Infrastructure Engineering and International Development, University College London and a Trustee at the Institution of Civil Engineers
Laura Bicker, BBC China Correspondent
Professor Kongjian Yu, Professor of Landscape Architecture at Peking University in Beijing
Katya Reyna, Co-Director of Depave, in Portland, USA

Producers: Graihagh Jackson, Ben Cooper and Joyce Liu
Mixing: Tom Brignell and Andy Fell
Editor: Simon Watts