Rural Revitalization and Regional Development
WANG Xiaqing, SUN Siyuan, YANG Ping, ZOU Xiaoyan, YI Qiaomei, PENG Baofa, XU Jianwei
Sponge city construction (SCC) is regarded as one of the effective ways to solve the urbanization problems in China, such as waterlogging, water pollution, water shortage and heat island. Since 2015, a total of 30 pilot cities had been set up as sponge cities for providing the models of a nationwide SCC in the future. Nevertheless, the studies about the SCC mainly concentrated on its concept, planning and goal in some pilot cities, few are known about the changes of the ecological effects under the SCC. As the first city in China to accept the sponge city concept and put it into practice, the Changde city, Hunan province, with the Chuanzi River catchment as the study area, provides the ideal area to evaluate the ecological effects under the SCC in China due to a longer SCC history over the period of 2004-2019. In this study, the ecological effects under the SCC in this catchment were analyzed based on field investigation and the comparsion of the measured data of hydrology, vegetation, and temperature before and after the SCC. The results showed that the SCC effectively alleviated the waterlogging in the Changde city, but some waterlogging sites still presented at the different areas in the catchment under the rainstorm. Meanwhile, the water quality in the Chuanzi River had been generally improved from bad Ⅴ to Ⅲ grade, but there was periodically deterioration due to the pollutants enrichment in the water during the winter seasons, which were the results from both closed water system and low temperature environment. In addition, the biodiversity in the catchment had significantly increased, but it also showed some existing problems at the same time including single plant species, few plants with environmental purification functions, incomplete ecosystem and poor management. Besides, the SCC had alleviated the heat islands in summer in the Changde city to some extents. As a result, the SCC over the period of 2004-2019 in the Changde city has significantly improved the ecological effects at the Chuanzi River catchment, which provides an important ecological basis for the socio-economic development and the improvement of the living environment in this area, and provides the reference for the reasonable evaluation on the SCC effects in other pilot cities in China.