To cope with rapid urbanisation, poor water management and heavy precipitation brought on my climate change, China is embracing the idea of sponge cities in which almost every drop of rainwater is harvested for use within its own boundaries.
According to an article in the Guardian, half of China’s 657 cities are considered water scarce or severely water scarce by UN measures, and another half fall short of national flood protection standards. To make its cities more resilient, China has chosen 16 urban districts across the country to become pilot ‘sponge cities’, in which rainwater is collected and reused to replenish depleted aquifers, irrigate gardens and urban farms, or even be treated and used for drinking water.
“It’s a new way of thinking about stormwater, not as a problem but as an opportunity and a resource to augment our water supply,” Richard Luthy, professor of civil and environmental engineering at Stanford University, is quoted in the article.
Each city will receive up to USD 94 million over the next three years to implement various measures: from developing ponds and wetlands to planting rooftop gardens, and even building permeable roads and public spaces for stormwater to soak into the ground. The goal is to manage 60 per cent of the rainwater falling in the cities.
As the article explains, sponge cities have benefits far beyond sustainable water management. Changde, a city 1,200 kilometres west of Shanghai, cut its engineering bill for new drains in half when it replaced 15 per cent of its concrete surface with bioswales, which are ditches filled with native plants that naturally collect and filter rainwater. According to Qui Baoxing, a former vice minister of housing and urban-rural development, sponge cities can even reduce carbon emissions in the long run.