High- and Low-Flow Variations in Annual Runoff and their Response to Climate Change in the Headstreams of the Tarim River

Global climate change is a hot issue for the international scientific community. Surface runoff, which is indispensable in the natural hydrologic cycle, relates closely to climate factors such as precipitation, air temperature and evaporation. The response of runoff to climate factors is more sensitive in arid and semi-arid areas, where a slight climate fluctuation can affect runoff fluctuation to greatly varying degrees. For this reason, exploring the high- and low-flow variation in the regional runoff and its response to climate factors will help realize the sustainable development of the local economy and environment.

The precipitation and air temperature of Xinjiang both had increasing trends in recent years, with marked spatial and temporal differences, and the Tarim River Basin has suffered severe flood disasters. Therefore, more studies focus on the runoff change of Tarim River Basin and its response to the regional climate change.

On the basis of measured data of air temperature, precipitation and annual runoff for the northern and southern headstreams of the Tarim River in a recent 50-year period, LING Hongbo et al. analyzes variation trends and abrupt changes of high- and low-flow indexes (Z index) and climate factors employing a nonparametric test, explores the periods and coming variations of air temperature, precipitation and high- and low-flow indexes (Z index) by using the wavelet analysis, and discusses the correlation between high- and low-flow indexes (Z index) and climate factors (air temperature and precipitation) on multiple time scales using cross-wavelet spectra.

The results show that the annual runoff volume and air temperature both had significant increasing trends, while precipitation had an unremarkable increasing trend over the northern and southern headstreams. There were abrupt changes in precipitation in the north and south in 1990 and 1986, respectively. There was a remarkable abrupt change for high- and low-flow indexes of annual runoff in 1993, and an abrupt change in air temperature in 1996.

In the case of the northern headstreams, there was significant periodicity of 6 years in both high- and low-flow indexes and air temperature and of 3 and 8 years in precipitation. In the case of the southern headstreams, there was significant periodicity of 3 and 9 years in high- and low-flow indexes, 5 years in air temperature, and 5 and 8 years in precipitation. The high- and low-flow indexes related closely to the air temperature and precipitation over the headstreams of the Tarim River.

The result provides a scientific evidence for the sustainable development of basin water resources. This research has been published in the international journal of Hydrological Processeson on 30 March 2013, 27(7): 975-988.