Characteristics of runoff changes and their climatic factors in two different glacier-fed basins

The hydrological regulation function of glaciers in different watersheds is different. This study took the Yanggong River Basin (YRB) and Urumqi River Basin (URB) as two typical cases, to explore the runoff change differences and their responses to climate factors during 1979-2017 using the Mann–Kendall test and correlation analysis method. In the past 39 years , the annual runoff in the YRB showed insignificant trend of increasing first and then decreasing. In contrast, the URB’s increasing trend was significant. In the YRB, from the 1980s to the 2010s, the monthly runoff extremum occurred earlier than before, and the peak value is decreased. The time of monthly runoff extremum in the URB has not changed, but the peak value is increasing. Both basins showed an increasing trend in the annual temperature from 1979 to 2017, and the temperature rise in the URB was faster than in the YRB. The precipitation in the two basins did not show a significant increase or decrease trend from 1979 to 2017. The main influencing factor of runoff change in the YRB is the precipitation during flood season. The temperature rise causes an accelerated melting of the glaciers and snow cover, which, in combination with the summer precipitation change, contributed to the increase of runoff in the URB. In continental glacier basins with many glaciers, the regulation function of glaciers on total runoff is more significant.