Review of Sponge City implementation in China: performance and policy.

Urban flooding is a major problem for large cities around the world. Rapid urbanization in China has tremendously increased, resulting in more frequent incidences of urban flooding. In 2013, China launched a program of 30 pilot sponge cities (SPCs) to establish integrated urban stormwater management. However, today, after several years of implementation, some sponge cities still experience flooding. This study provides answers and solutions to these problems, by evaluating the overall performance of SPC in China from a systematic perspective considering the variable climatic conditions. This paper also highlights the limitations associated with implementing the current SPC. The adoption of overseas models, before adhering them to Chinese catchment properties, has generated significant uncertainty for simulation outputs and material provision challenges at various stages of the implementation process. Furthermore, hydrological connectivity between neighboring catchments has been neglected in most SPC projects. Developing local models based on local conditions and needs would address these issues and open new research windows for exploring more effective stormwater management initiatives. That includes the advancement of cost-effective evaluation studies, modern optimum efficiency design studies, and the analysis of groundwater contamination due to high infiltration rates and so on.