Wang Hao, Wang Jia, Liu Jiahong, Mei Chao

Global climate change and rapid urbanization have profoundly changed the process of natural water cycle, which lead to a presentation of nature-society dualistic water cycle. City is the region with the deepest coupling degree of dualistic water cycle. The driving force, structure and process of urban water cycle tend to complicate and imbalance, which causes more and more prominent urban water issues. In this study, the root cause of urban water issue is analyzed on the basis of identifying the evolution process and mechanism of urban water cycle. Guided by urban water issues and future evolution trend of urban water cycle, the theoretical framework of urban water cycle optimization in the future which contains four strategies of "water governance", "water use", "water regulation" and "water management" is addressed, and the eight-word guideline -"safety", "harmony", "smooth", "protection", "saving", "reuse", "clean" and "intelligence" to realize the optimization of urban water cycle in the future is expounded.

Keywords: urban water cycle, nature-society dualistic water cycle, water cycle, urbanization, urban hydrology