It used to be that cemented channels and underground piping in cities controlled storm flows so water would run off quickly….but now such ‘gray’ infrastructure is being replaced by the green infrastructure of  ‘sponge cities’, accommodating rainfall instead of fighting it. It has been policy in China since 2015 and is becoming more common in cities globally.

The urban designer most responsible for China’s sponge city rollout is Yu Kongjian, dean of Peking University’s college of architecture and landscape. As a child, he nearly died when swept into the flooding creek near his farming commune. Willows and reeds along the bank made it possible for him to climb out. Today, with concrete flood walls, he would have drowned, he told the BBC. It was a powerful lesson about the value of ‘green infrastructure’ in an era of climate change.