Sponge city ideas to reduce urban flooding in Asia ^{CEFR B1}

Extreme weather and heavy rain have caused severe urban flooding across Southeast Asia. In March 2025 torrential rains inundated Jakarta and nearby areas, killing at least nine people and displacing 90,000. Manila and Ho Chi Minh City also saw exceptional downpours: a storm in metropolitan Manila delivered about five days of rain in one hour, and heavy thunderstorms left more than a metre of water in parts of Ho Chi Minh City.

The sponge city concept entered Chinese national policy in 2013. Proposed by Yu Kongjian and supported by President Xi Jinping, it uses natural methods to retain and purify rainwater. Instead of draining water fast with pipes, sponge measures absorb and slowly release rain. Typical measures include green roofs, rainwater storage and infiltration systems, permeable pavement and wetland revitalization.

Pilot projects in China have improved stormwater runoff control and helped in some poor geographical areas. Bangkok applied the idea at Benjakitti Forest Park, which reduced stormwater force and filtered polluted water; during a 10-year rainfall event in summer 2022 the park and nearby areas did not flood while much of Bangkok did. However, many pilots are local, and scaling up needs cross-department collaboration and political will. Critics point to record storms, such as the 2021 Henan floods that killed 292 people in Zhengzhou, and say sponge designs alone may not be enough.