SPONGE CITIES

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Context

China's "sponge city" initiative and its efforts to address the challenges posed by urban flooding and water management.

Details

• China facing devastating floods, raising questions about the effectiveness of the 2015 "sponge city" initiative.
• Aimed at reducing urban flood risks and improving water management in major cities through nature-based solutions.

Background and Rationale

• China's history of extreme weather and vulnerability to flooding and drought.
• "Sponge city" initiative launched to address flooding and improve water distribution and storage.
• Encroachment of impermeable concrete due to rapid urbanization, leading to waterlogging and flooding.
• 2018 data showed widespread vulnerability to flooding and waterlogging in Chinese cities.

Implementation and Progress

• Positive effects seen in local pilot projects, such as green roofs and rain gardens reducing run-offs.
• Selection of 30 pilot sponge cities in 2015-2016, but patchy implementation.
• Only 64 out of 654 cities had legislation to implement sponge city guidelines by last year.
• Lack of sufficient attention from the government, calls for national legislation.

Limitations of Sponge Cities

• Inadequate to prevent recent devastating floods.
• Example of Zhengzhou, allocated substantial funds but was overwhelmed by historical rainfall in 2021.
• Sponge city infrastructure's capacity is limited to handling up to 200 mm of rain per day.
• Rainfall levels far exceeded this capacity in recent rainstorms, revealing the infrastructure's limitations.
• Climate change and unexpected heavy rain hitting less-advanced sponge city development areas.

https://indianexpress.com/article/explained/explained-global/china-sponge-cities-floods-explained-8885495/