How do urban rainfall-runoff pollution control technologies develop in China? A systematic review based on bibliometric analysis and literature summary.

Rapid urbanization in China is driving the need of urban rainfall-runoff pollution control technologies due to adverse impacts on water environment. In this study, literature from China National Knowledge Infrastructure, Web of Science and Scopus in 1995/1/1-2019/5/15 are used to review research hotspots, development process and future directions of urban rainfall-runoff pollution control technologies in China and global world. Temporal evolution of publications showed that source reduction played better growing trend in urban rainfall-runoff pollution control field for both China and global world. Furthermore, with bibliometric tool, density visualization maps and co-occurrence network maps were created to identify research hotspots in China and global world. By comprehensively analyzing research hotspots above and development process from extracted literature, future directions of urban rainfall-runoff pollution control technologies were predicted. For model and strategy, both China and global world would concern on the accuracy of models to evaluate combination technologies. For source reduction, China would explore rainwater purification in sponge city, while global world would investigate match characteristics between specific regions and control technologies, combination between model and technologies, and improvement of pollutants removal. For process control, China would enhance ecological gutter inlet performance, whereas global world would concentrate on optimization of rainwater harvesting system. For post treatment, China would estimate modified hydrocylone and coagulation technology, and improve performance of filtration systems, riparian buffers and constructed wetlands, while global world would explore ecological and landscape function of constructed wetlands. Since China ranked first in producing Western publications and was the second most cited country for Western publications recently, China would significantly influence future development of urban rainfall-runoff pollution control technologies around the world. Meanwhile, some directions including infiltration basin and rainwater harvesting system were still shortcomings for China due to a late start of urban rainfall-runoff pollution control technologies in China.