Dr. Rain Explains How to Make Cities "Breathe" Like Sponges

Every rainy season, waterlogging becomes a pressing issue for many cities. As an exploration and innovation in urban planning, design and construction, the concept of sponge cities offers a viable approach to restoring aquatic ecosystems and conserving water resources. Earlier, Guangzhou City in Guangdong Province issued an administrative measure for sponge city construction, clarifying the work to advance sponge city development, establishing a sound construction system, and putting in place a long-term mechanism for the construction and daily maintenance of sponge city facilities.

A sponge city, by definition, refers to an urban development model that strengthens urban planning, construction and management, gives full play to the roles of ecosystems—such as buildings, roads, green spaces and water systems—in absorbing, storing, infiltrating and slowly releasing rainwater, effectively controls rainwater runoff, and achieves the natural retention, infiltration and purification of rainwater. In other words, a city can function like a sponge: absorbing, storing, infiltrating and purifying rainwater when it rains, and "releasing" and utilizing the stored water when needed. It thus demonstrates good "resilience" in adapting to environmental changes and coping with natural disasters.

In recent years, many regions have steadily advanced sponge city pilot projects, achieving positive results in preventing and controlling urban waterlogging and safeguarding urban ecological security. In Pingxiang, Jiangxi Province, over 80% of the built-up areas meet sponge city standards, gradually fulfilling the overall goal of "no water accumulation during light rains, no waterlogging during heavy rains, no black and odorous water bodies, and mitigation of the heat island effect". In Baicheng, Jilin Province, sponge city construction has resolved the water shortage problem that plagued urban development, transforming the once "wind-swept sandy city" into a "water town" in Northeast China. With the popularization of sponge city initiatives, more and more regions are adhering to an eco-first and green development approach, and beginning to re-examine the relationships between humans and cities, humans and nature, and cities and nature.

In the long run, sponge cities can not only treat pollution and store water, but also build a sound ecological operation system that "integrates cities into nature". Facilities such as rain gardens and sunken green spaces realize the regulation, storage and purification of rainwater, creating ecological landscapes compatible with nature. Urban parks and tree-lined green belts provide higher-quality and livable environments, enabling residents to "see mountains, view waters, and cherish their hometown nostalgia". In this sense, the ultimate goal of building sponge cities is to create eco-friendly cities featuring blue skies, white clouds, twinkling stars, clear waters, green riverbanks, and fish swimming in shallow waters.

It should also be noted that in the face of sudden rainstorms and floods, some regions lack adequate prevention and emergency response measures. In terms of the design and construction of sponge cities, a few areas pursue overly rapid progress and comprehensive coverage without proper consideration. Constructing sponge cities is a long-term and arduous process that requires persistent efforts, sustained patience, a scientific mindset and systematic methods. Only by continuously deepening sponge city construction and advancing it steadily step by step can we steadily enhance people's sense of gain, happiness and security, and promote the high-quality development of cities.

The Outline of the 14th Five-Year Plan for National Economic and Social Development and the Long-Range Objectives Through the Year 2035 proposes building an urban flood control and drainage system that focuses on source pollution reduction, combines storage and drainage, addresses waterlogging risks, and responds to excessive rainfall emergencies, striving to achieve notable results in urban waterlogging control. Enabling cities to "breathe" like sponges, creating a beautiful ecological environment with green mountains and clear waters, and building high-quality modern cities will help turn a sound ecological environment into a growth driver for people's quality of life and a focal point for showcasing a beautiful urban image, ultimately realizing the vision of livable and happy cities.