AdvertisementMaking cities 'spongy' could help fight flooding — by steering the water underground05:31Download AudioResumeOctober 03, 2023John RuwitchfacebookEmailThis natural pond helps reserve precipitation in the ecological corridor of Qian'an, a city in China's Hebei province. Like many other Chinese cities, Qian'an used to fall victim to urban flooding during rainy seasons. But things have changed since 2015, when the city was included in a national pilot program for "sponge city" construction. (Mu Yu/Xinhua via Getty Images)