China Sponge City database development and urban runoff source control facility configuration comparison between China and the US.

Urban runoff source control facilities (URSCFs) are important parts of Sponge City (SC) by controlling urban flooding, restoring eco-balance, and enhancing city resilience. To evaluate the performance of URSCF, one needs to summarize and analyze the past SC construction and operation data. Previous studies however are predominately engineering practice studies. There lacks localized reference datasets to quantitatively evaluate the performance and guide public policy development for SC. Therefore, it is imperative to develop a database, which would summarize data obtained through the already completed pilot sponge cities, and provide a reference for future URSCFs planning and construction. This study makes a zero to one breakthrough by establishing a SC database using New Orleans method. Then statistical results of facility type, size, and costs information for 30 pilot sponge cities have been summarized and analyzed. The URSCFs type distribution statistical results show that bioretention, permeable pavement, detention cell, grassed swale and constructed wetland are the top five most constructed facilities in China. The cost statistical results display that the range of facility cost collected is usually larger than the range given by the reference value, which may attribute to the variation in material cost, labor cost and design parameters in different cities. To check the similarities and differences of URSCFs parameters between China and the US. A configuration parameters comparison of URSCFs has been conducted. Bioretention is taken as an exampl. Comparison results show that factors such as climate type, geographical environment, and socio-economic conditions will affect the configuration parameters of URSCFs. The groundwater depth and designed rainfall intensity are mainly influenced by local climate and geographical conditions. Surface area is influenced by local socio-economic conditions. The thickness of the covering layer and drainage layer are not affected by geographic location. The service area ratio, water storage depth and planting soil layer thickness are significantly different between China and the US.