RESEARCH AND APPLICATION ON RAINWATER TREATMENT TECHNOLOGY IN SPONGE CITY BASED ON SUSTAINABLE DEVELOPMENT

In recent years, geological disasters caused by heavy rainfall in Chinese cities have gradually intensified. The construction of sponge cities that can effectively reduce the damage of rainfall has become an objective requirement for sustainable urban development. In this paper, taking North China as an example, the artificial measures to effectively control rainfall hazards in sponge cities have been systematically analyzed, including the design of biological retention ponds, the optimization of garden plants, and the urban vegetation buffer zone. An improved biological retention pond was designed, and its internal structure is composed of super high-rise buildings, submerged layers (aquifers), overburden layers, composite filler layers, and gravel layers. The gravel layer is the drainage system of the biological retention pond, and the gravel size of the filled gravel is 12 to 35 mm, and the maximum size does not exceed 50 mm. The improved biological retention tank increases the height of the outlet pipe of the gravel discharge layer at the bottom of the retention tank to form an effective water storage depth, thereby providing a relatively anaerobic and aerobic layer. Garden plants in North China are preferably herbaceous plants that are resistant to saline, alkali, cold, drought, and waterlogging, namely, bamboo reed, day lilies and sedum spectabile boreau. The urban vegetation buffer zone is the vegetation area between the pollution source and rivers, rivers and streams. The scale design should satisfy that the slope is greater than 2% but less than 6%, and the width is greater than 2 m. The vegetation buffer zone can not only purify rainwater, but also has a good landscape effect. Vegetation buffer zones in small watersheds can replace rainwater pipes to form a rainwater system for water delivery and purification.