![]() ![]() “Dams are typically triumphed as flood mitigation tools, but as dams get larger, they tend to complicate flooding controls due to the unpredictability of climate change,” says Kirk Barlow, an Asia-focused staff member of International Rivers, an Oakland, California, nonprofit devoted to protecting rivers. The government’s emphasis on building dams, dikes, and levees to prevent riverine floods has been less effective in ensuring the protection of growing cities on floodplains, especially amid extreme rain, experts say. The problem has also spurred a rethinking of the traditional “gray,” or hardened, flood-control infrastructure predominant in China, which has constructed 97,000 dams since the 1950s. ![]() How these HBCU presidents fixed their colleges’ financial futures Since 1978, China’s urban population has expanded fivefold to 900 million – 64% of its population of 1.4 billion people now lives in cities. Underlying the rising danger of climate change-induced flooding in Chinese cities is the country’s unprecedented urbanization. ![]() The task ahead for China’s government is not to abandon the more sustainable and ecologically friendly approach to absorbing and recycling stormwater, but to pay greater attention to climatic extremes and uncertainty, he says. “The sponge city program is good stuff, but it only can withstand the mild or large rainstorm” that comes once in 30 years, he says. “For this type of rain, the soil will be saturated very, very quickly,” Professor Chan says. The program is a window into how China is trying to balance the breakneck build-out of urban areas with environmental adaptions that potentially offer a model to other flood-prone nations.Īlthough Zhengzhou has spent more than $80 million since 2016 to create green belts, permeable roads, and collection wells to reduce flooding from heavy rainfall or overflow from major rivers, the intensity of last week’s rain rapidly submerged the area designed to absorb it. The government has invested more than $12 billion in the program since 2014 to help cities create sponge features on 20% of the land, with the goal of retaining or reusing 80% of annual precipitation by the 2030s. The soil then purifies that water and gradually releases it – much like a sponge. China’s nature-based approach to urban drainage may offer a partial solution.Ĭhina’s sponge city program aims to use pervious pavements, rain gardens, green roofs, urban wetlands, and other innovations to absorb water during storms. “Floods are not enemies we can make friends with floods,” he says.įlash floods are wreaking havoc in towns and cities across the world. Parks can be dry in some seasons and become channels during rainy months. Yu Kongjian, a landscape architect who came up with the sponge city concept, has said it offers a more harmonious relationship between humans and nature. “For this type of rain, the soil will be saturated very, very quickly,” says Faith Chen, a professor of environmental science.įor China, where 64% of people now live in cities, this approach is a departure from the construction of dams, dikes, and levees. Experts say the intensity of the rains – about a year’s worth in only four days – was too much for these features to absorb in such a short period of time. Last week’s record downpour in central China caused chaos in Zhengzhou, where subways and highways flooded despite the city having sponge features in place. These “sponge cities” are a response to the increasing risk of flooding in cities that climate change has made more vulnerable than ever. Since 2014, China has invested billions of dollars to build natural features in cities that can absorb water during storms. ![]()
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