CHINA'S SPONGE CITIES
- A sponge city is a new urban construction model for flood management, strengthening ecological infrastructure and drainage systems, proposed by Chinese researchers in early 2000 and accepted by the Chinese Communist Party (CCP) and the State Council as urbanism policy in 2014.
- It can alleviate urban flooding, water resources shortage, and the urban heat island effect and improve the ecological environment and biodiversity by absorbing and capturing rain water and utilizing it to reduce floods.
- Rainwater harvested can be repurposed for irrigation and for home use.
- According to 2018 data, 641 out of 654 large- and medium-sized cities in China were vulnerable to flooding and waterlogging, with 180 facing flood risks every year
- A total of 30 pilot sponge cities were selected in 2015 and 2016.
- By last year, only 64 of China’s 654 cities had produced legislation to implement sponge city guidelines
- Experts believe sponge city infrastructure can only handle no more than 200 millimetres (7.9 inches) of rain per day
- At the height of the rainstorms that lashed Beijing at the end of July, rainfall at one station reached 745 millimetres over three and a half days.
- In July 2021, Zhengzhou saw rainfall in excess of 200 mm in just one hour.
Sponge cities hold significant importance due to their potential to address a range of urban challenges, particularly those related to water management, climate change, and urban development. Some of the key significance of sponge cities include:
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Flood Mitigation: One of the primary benefits of sponge cities is their ability to manage and reduce the risk of flooding. By incorporating features such as permeable surfaces, retention ponds, and natural waterways, sponge cities can absorb excess rainwater and stormwater, preventing it from overwhelming drainage systems and causing floods.
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Climate Resilience: Sponge cities are designed to adapt to the impacts of climate change, such as increased rainfall intensity and rising sea levels. Their water management strategies help cities better cope with extreme weather events, reducing vulnerability to flooding and related damages.
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Water Conservation: These cities prioritize the efficient use of water resources by harvesting and reusing rainwater and treating wastewater for non-potable purposes. This conserves freshwater supplies and reduces the burden on water treatment facilities.
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Innovation and Technology: Sponge cities encourage the development and adoption of innovative technologies and solutions for urban water management. This can drive technological advancements and create opportunities for research and development.
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Community Engagement: The concept of sponge cities often involves community engagement and education about water management and climate resilience. This can lead to increased public awareness and participation in sustainable practices
- Even if sponge city measures had been implemented in full, they would have been unable to prevent this year’s disasters.
- Zhengzhou in Henan province was one of the most enthusiastic pioneers of sponge city construction, allocating nearly 60 billion yuan to the programme from 2016 to 2021. But it was unable to deal with its heaviest rainfall in history in 2021
- Experts believe sponge city infrastructure can only handle no more than 200 millimetres (7.9 inches) of rain per day.
- At the height of the rainstorms that lashed Beijing at the end of July, rainfall at one station reached 745 millimetres over three and a half days
- China has long sought to improve the way it handles extreme weather, and make highly populated cities less vulnerable to flooding and drought
- The "sponge city" initiative was designed to make greater use of lower-impact "nature-based solutions" to better distribute water and improve drainage and storage
- Those solutions included the use of permeable asphalt, the construction of new canals and ponds and also the restoration of wetlands, which would not only ease waterlogging, but also improve the urban environment
- According to 2018 data, 641 out of 654 large- and medium-sized cities in China were vulnerable to flooding and waterlogging, with 180 facing flood risks every year
