Abstract: Runoff in the source region of the Yangtze River has undergone great changes in recent decades.It is of great practical significance to study the characteristics of runoff variation under the background of global warming for understanding the hydrological effects caused by climate change.The evolution of runoff and its relationship with meteorological factors such as precipitation, temperature, and evaporation were analyzed based on measured hydro-meteorological data from 1960 to 2019 at Tuotuo River.The relationship between δ¹⁸O records and ice core accumulations among different ice cores, and the correlation between ice core records and runoff in Tuotuo River were examined.The 10-year moving average runoff series of the Tuotuo River from 1900 to 1960 was reconstructed, and the runoff variation of Tuotuo River over the past century was analyzed.Results revealed a siginificant increase trend of annual runoff of Tuotuo River around 2002.The increase in glaciers and snow melt induced by the sharp rise in temperature is an important cause for the sharp increase in flow rate in the source region of the Yangtze River.The reconstruction of the runoff series of Tuotuo River since 1900 demonstrated that the source area of the Yangtze River had experienced many alternating dry-wet changes, and the runoff variation rules are in general consistent with the three abrupt climate changes in the Tibetan Plateau.The research findings provided a basis for revealing the evolution law and hydrological response of river runoff in the source region of the Yangtze River under climate change.

Key words: runoff, water resources, ice core, Tibetan Plateau, source region of the Yangtze River