Response of Runoff in the Upper Reaches of Yangtze River to Climate Change over the Eastern Part of Tibetan Plateau

The possible association between climate change over the eastern part of Tibetan Plateau and the variability of water resources in the upper reaches of Yangtze River is investigated in this research. The long-term trend of the hydro-meteorological time series including the annual mean temperature, annual precipitation and annual mean runoff are detected by using both parametric and nonparametric techniques. The result shows that the annual mean temperature exhibited an increasing trend being statistically significant at the level of a=0.05 during the past 43 years, and the annual mean temperatures have increased by 0.0132°C per year. Annual precipitation also exhibited a slight and insignificant increasing trend during the past several decades. The annual runoff series in the upper reaches of Yangtze River shows a slight and insignificant decreasing trend during the past 111 years, which decreased with a speed of about 7.2464m3/s per year. The result of jump test by using the SVMK test indicates that significant jumps in the late 1990s for the annual mean temperature time series and around 1923-1924 for annual mean runoff time series did occur. The future climate scenarios over the eastern part of Tibetan Plateau and its impact on the runoff in the upper reaches of Yangtze River are tentatively discussed. In the future decades, the runoff in the upper reaches of Yangtze River will largely decrease under the conditions of temperature increasing obviously and precipitation decreasing greatly, whereas it will increase under the conditions of temperature immovability and a great increase in precipitation and the change rate of runoff may be greater than that of precipitation. This research enhances the knowledge of the climate change impact on water resources in the Yangtze River.