In the rainy season, cities turn on the "sea-viewing mode"? "Sponge" makes cities "water-absorbent"!

In recent years, many cities have turned on the sea-viewing mode every rainy season, and urban waterlogging has become a major problem in urban water management. As the concept of ecological civilization construction has gained popularity, cities have started a new water management model - sponge city construction. Sponge city construction provides a new idea for solving urban waterlogging.

What is a "sponge city"? A sponge city is a city that has good water absorption and elasticity like a sponge. It absorbs, purifies and stores water when it rains, and releases and utilizes rainwater when needed. Through the construction of sponge cities, 70% of rainfall can be absorbed and utilized on site.

A permeable brick used in the sponge city transformation process in Pingxiang City, Jiangxi Province (Source: Xinhuanet)

So how can we make the city function like a "sponge"? The key lies in building a "sponge body". First, we need to green the hard surfaces of the city, introduce a series of "small sponge" facilities such as permeable pavement, grass-planted ditches, sunken green spaces, and rain gardens. These are like absorbent mats at home. When rain falls, part of it is stored in the rainwater retention area, part of it penetrates underground to replenish groundwater, and the rest enters the underground waterway through the rainwater pipe network. By effectively controlling the external rainwater runoff, the pressure of rain and flood can be dispersed from the source.

Although my country has been continuously promoting the construction of sponge cities, urban flooding has occurred from time to time. People can't help but wonder if the construction of sponge cities has "failed"? In fact, the construction capacity of sponge cities is limited. When faced with extreme rainstorms that exceed the design standards, it is like a sponge that has absorbed enough water. The water will definitely overflow.

Therefore, it is difficult to cure waterlogging by reducing rainwater discharge at the source and using traditional shallow underground drainage systems. It is also necessary to build pipe network pump stations, underground deep tunnel projects and large-scale storage projects to drain or store rainwater. However, due to the high investment and implementation difficulties, most cities will need more time to achieve this.

A newly renovated permeable ground in a residential square photographed in Haigang District, Qinhuangdao City (Source: Xinhua News Agency)

Finally, we also need to regulate the "big sponges" such as urban water systems and rivers at the watershed scale, collect rainwater from the rainwater pipe network, and discharge flood water to the drainage sluice stations to better play the role of urban sponges.

Through the combination of large, medium and small sponges, our city can not only effectively prevent urban flooding, but also promote the resource utilization of rainwater and improve the ecological environment quality of the city.

From 2021 to 2023, the Ministry of Finance, the Ministry of Housing and Urban-Rural Development, and the Ministry of Water Resources have successively selected three batches of 60 sponge city construction demonstration cities through competitive selection. They have achieved remarkable results in systematically promoting sponge city construction across the board.

People's livelihood is the most important thing, and water management is the key. In the process of continuously promoting the construction of sponge cities, water conservancy researchers will continue to support the comprehensive management of river basins, work hard, and jointly write a new chapter in water management and development in the new era!