Abstract: The Tibetan Plateau, known as the "Asian Water Tower," is essential in terms of hydrology, climate, and ecology. At the moment, our understanding of the hydrological functions of the water tower is mostly focused on its storage function, with little attention paid to its regulation function and mechanism. In terms of watershed preservation and regulation, this study describes the hydrological functions of the water tower’s water storage and regulation, and the hydrological functions and storage-regulation mechanism of multi-phase water towers. The Tibetan Plateau Water Tower not just has a powerful function of water storage, but plays other roles－redistributing precipitation over the water tower region; adjusting the runoff and its distribution within a year in the non-water tower regions, and regulating water resources such as precipitation, surface water, soil water, and groundwater in the basin. This study helps lay a basis for assessing the ecological and hydrological impact of the water tower on the upper and lower basins of the plateau, useful for protection and regulation of the water tower on the basins, so as to meet the production, living, and ecological water needs of this region and its surroundings through rational planning of water conservancy projects.

Key words: hydrological cycle, Tibetan Plateau, Asian Water Tower, hydrologic function, regulating function, storage and regulation mechanism