- Chinese cities are struggling with flooding in urban, concrete areas
- Sponge cities aim to capture and utilize this rainwater
Recent flooding in Mumbai was blamed in part on unregulated development of wetlands, while hastily built urban areas are being affected by flooding across India, Nepal, and Bangladesh.
This is not a trend only in developing countries; floods in Houston, United States, highlighted the risks of development in environmentally sensitive and low-lying areas. In 2012, a severe flood in Beijing wreaked havoc on the city's transportation systems, and in 2016 floods overwhelmed drainage systems in Wuhan, Nanjing, and Tianjin.
The challenges are clear.
Groundwater over-extraction, waterway degradation, and urban flooding are forcing China's cities to address a vicious cycle. Sprawling urban development and use of impervious material prevent soil from absorbing rainwater, prompting further investment in infrastructures that typically impede natural processes and worsen flood impacts.
China's "sponge city initiative" aims to arrest this cycle through the use of permeable surfaces and green infrastructures.
However, the initiative faces two challenges: lack of expertise of local governments to effectively coordinate and integrate such a complex set of activities, and financial constraints.
Engineering solutions are popular interventions, but cities cannot simply pipe away flood risks.
To address the issue, China's sponge city initiative has an ambitious goal: by 2020, 80% of urban areas should absorb and re-use at least 70% of rainwater.