The problem

China faces twin water crises. Its urban population faces both flooding and water shortages.
On 21 July 2012, a flash flood hit Beijing, China. Close to 57,000 people were evacuated and 79 died, with economic losses in the range of USD 1.5 billion – prompting calls for urban stormwater and drainage management reforms.
But urban populations have to contend with water shortages. After decades of rapid urbanisation and pollution, water scarcity is a major urban planning issue – exacerbated by climate change and unsustainable water management methods. Moreover, water quality is worsening and urban drainage infrastructure is poor, resulting in combined sewer overflow, erosion and sedimentation, groundwater shortage, and heat island effect. To offset the adverse impacts of rapid urban development and address water-related problems in cities, the Government of China introduced the sponge city concept in December 2013.

The solution

A sponge city uses landscapes and green infrastructure to retain valuable water resources at source and promote natural retention, infiltration, and purification – like a sponge – for drainage. The government’s goal is to use nature-based solutions and upgraded urban drainage infrastructure to manage approximately 70% of the runoff in 20% of urban lands by 2020, and 80% of urban lands by 2030.

The method

The sponge city concept is not new; it is in line with many modern urban stormwater management concepts in developed countries, such as best management practices and low impact development in North America, sustainable urban drainage systems in the UK, and water sensitive urban design in Australia.
However, China’s sponge city concept integrates many other innovations, from novel materials to new management methods, from new planning concepts to additional green infrastructure operation and maintenance strategies, and from site-scale stormwater structure to basin-wide and nationwide change in development paradigm.

The results