Nearly one-third of built-up urban areas in Hunan Province have been built into "sponge cities." So far, a total of 536 square kilometers of provincial “sponge cities” have been constructed to meet the sponge city standards, accounting for 27.43% of urban built-up areas, according to the 2021 Summit on Carbon Emission Peaking and Carbon Neutrality in Yangtze River Middle Reaches City Cluster (Double-Carbon Summit), also the Green Expo on October 23.

A sponge city is one in which urban precipitation is absorbed into the groundwater rather than running off into watercourses. The idea is to make best use of rainwater and prevent flooding. These sponge cities typically feature roof gardens, large numbers of trees, vast areas of lawns and permeable pavement.

The increasing development of urbanization has brought about a series of eco-environmental problems, among which water ecological problems are particularly prominent. The "sponge city" can help realize the harmonious coexistence of water ecology, water environment and human settlement environment, and therefore has become a new model of urban development in which man and nature coexist harmoniously. Since 2015, Hunan Province has systematically promoted the construction of sponge cities throughout the region based on the construction of one national pilot project and four provincial-level pilot projects. The province has carried out "sponge city construction" in water systems, parks, public green spaces, roads, communities, and roofs. A number of typical projects with remarkable results were initially completed, such as the Guitang River project in Changsha City and the Dongfeng Lake project in Yueyang City.

The "Forum on Sponge City Construction in Yangtze River Middle Reaches City Cluster from the Perspective of Carbon Neutrality" was specially organized. Experts and industry leaders in related fields discussed cutting-edge technologies of sponge city construction and shared experience and results.

During the forum, Key Laboratory of Urban Rainwater System and Water Environment of the Ministry of Education, Beijing University of Civil Engineering and Architecture; Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology of Beijing Normal University; and, Yueyang Sponge City Construction Steering Group Office signed the "Cooperation Agreement on Sponge City Technology Support and Talent Training". As agreed, they will carry out cooperation in the fields of scientific research, technologies, products, processes, and plans, and accelerate "sponge city" construction in Yueyang City.