China's 'sponge cities' aim to re-use 70% of rainwater

Story highlights

  • Chinese cities are struggling with flooding in urban, concrete areas
  • Sponge cities aim to capture and utilize this rainwater

Asit K. Biswas is a distinguished visiting professor at the Lee Kuan Yew School of Public Policy, National University of Singapore. Kris Hartley is a lecturer in city and regional planning at Cornell University.

(CNN)Asian cities are struggling to accommodate rapid urban migration, and development is encroaching on flood-prone areas.

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.