Can sponge cities prevent flooding?
China has committed to the “Sponge city” initiative in a bid to reduce/prevent the damage caused by flooding to its urban areas. The concept of sponge cities is to reduce flooding risk by increasing permeable surfaces and directing water runoff to underground storage systems through nature-based solutions. Chinese cities that already implemented this concept include Baicheng, Qian’an, Jiann, Xixian.
Such solutions include 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.
Breakneck urbanization has encased vast stretches of land in impermeable concrete, often along banks of major rivers that traditionally served as flood plains. With wetlands paved over and nowhere for surplus water to settle, waterlogging and flooding was commonplace.
Fast forward to 2024, Chinese cities are still susceptible to flooding damage caused by heavy rainfall. As per China’s emergency ministry, in July 2023, floods and related geological disasters caused 142 deaths and disappearances, destroyed 2300 homes, and caused direct economic losses of $2.19 billion.
Experts believe that sponge city infrastructure can only handle no more than 200 millimetres (7.9 inches) of rain per day. In the recent past, Beijing received 745mm rainfall in three and a half days, Zhengzhou saw rainfall of upto 200mm in just one hour.
Given the advantages and limitations of the sponge city infrastructure, it looks to be a solution in the right direction towards mitigating flooding risks caused by breakneck urbanization and changing weather patterns.
