Tim McCready

Project Auckland: International cities show how to soak up stormwater

Project Auckland: International cities show how to soak up stormwater

In 2015, China implemented a concept known as “sponge cities” in 16 urban areas to combat flooding caused by stormwater.

The initiative was in response to the devastating Beijing flood in 2012, which claimed 79 lives and prompted authorities to make sponge cities a nationwide policy.

The idea was promoted by Chinese landscape architect Yu Kongjian, who advocated for the integration of nature’s ability to absorb, store and filter water into city infrastructure to mitigate against runoff.

This approach involves using green infrastructure to allow water to follow its natural channels, with streams and creeks uncovered, parks and grasslands restored, and planting used to slow down the flow of water and enable natural absorption, infiltration and purification. This is in stark contrast to the conventional grey infrastructure solution that speeds up the flow of water using pipes and drains.

Qunli stormwater park, in the northern Chinese city of Harbin, is an example of the concept. The park collects, filters and stores stormwater, and has become a popular urban amenity for recreational use. Capable of retaining and filtering up to 500,000 cubic metres of stormwater, the park has solved the stormwater inundation issue for an area 10 times its size, spanning over three kilometres.