Guidelines issued

The nation aims to build sponge cities to mitigate the impact of torrential rain. Such cities absorb, store, filter and purify rainwater. When needed, they release and use stored water.

In 2014, the Ministry of Housing and Urban-Rural Development issued the Pilot Technical Guidelines for Sponge City Construction, designating Beijing among the pilot cities for this concept. The guidelines aim to create cities with the ability to adapt to environmental changes and effectively respond to natural disasters, functioning in a way similar to sponges.

Government departments, including urban planning, drainage, transportation and landscaping, are involved in guiding the process.

The guideline states that to build such cities, efforts should be made to prevent urban areas sprawling rapidly, and adequate areas of green space, along with footpaths made from permeable materials should be provided.

Other efforts should include connecting water systems such as rivers, lakes, wetlands, ponds and canals with urban rainwater pipe networks and excess rainwater discharge systems, the guideline states.

The ministry said that over the years problems have arisen, with some cities misunderstanding sponge city construction. These problems could hamper efforts to bolster resilience against disasters, according to a statement released by the ministry last year.

There are problems in building water filtration systems regardless of geological conditions, drawing drainage zoning boundaries based solely on administrative divisions, and adding drainage hurriedly after the completion of design plans for buildings, roads and gardens.

She Nian, head of the Smart Sponge City Planning and Construction Research Institute at the Tsinghua Innovation Center in Zhuhai, Guangdong province, told Southern Weekly on Wednesday that the carrying capacity of northern sponge cities is lower than that of southern cities.

"Northern cities need to improve awareness of how sponge cities tackle urban flooding, as in the past, northern regions have not experienced frequent rainfall or heavy storms like southern areas," She said.

During construction of sponge cities, attention should be paid to building green belts, rather than relying solely on traditional rainwater drainage systems, he was quoted as saying.

In 2021, the UN Office for Project Services, the UN Environment Programme and the University of Oxford co-published a report titled Infrastructure for Climate Action.

The report emphasizes the importance of treating infrastructure as a key area for addressing climate change — urging governments to reassess how to deliver and manage infrastructure to ensure it is suitable for a resilient future.

In recent years, cities worldwide have sought ways to enhance their resilience to climate change. However, implementing such measures often comes at a high financial cost.

One example is the case of New Orleans in the United States, and the city's suburbs located south of Lake Pontchartrain.

Following the destructive Hurricane Katrina in 2005, the federal government invested $14.5 billion on installing levees, pumps, seawalls, floodgates and drainage systems to carry massive amount of water away from houses and into wetlands.

This infrastructure has since protected the area from damage caused by storms, the Associated Press reported in 2021.