Long-term variation of observed streamflow at the headwaters of the
Urumqi River, eastern Tien Shan, at the multi-time scale
Abstract
Climate warming accelerates the melting of glaciers in the Tien Shan,
which not only causes the increase of annual runoff of rivers, but also
changes the law of variation of inner-annual runoff. In this paper, the
source of Urumqi River in the Tien Shan is taken as a typical glacier
region. Based on the observed hydrological and meteorological data for
the period 1980-2016, the results of multi-time scale of runoff showed
that the runoff of Urumqi Glacier No.1 and Zongkong catchment all
exhibited upward trends and experienced a significant amplification
after 1996 and 2008, respectively. The monthly mean discharge was
observed to be highest in July followed by August. The daily flow of
Glacier No.1 catchment increased before 2010 while the high flow had
almost no growth and the low flow declined about 12% after 2010. For
Zongkong catchment, the daily discharge showed an increment for both
high-flow and low-flow (Except the reduction in high-flow in 2000s compared
with the 1990s). The maximum discharge from the Glacier No.1 occurred in
the afternoon, and the minimum discharge occurred in the morning. For
the Zongkong catchment, the maximum discharge occurred in the evening or
early morning of the next day, and the minimum discharge occurred in the
afternoon. In the Glacier No.1 catchment, runoff variability was mainly
due to the effect of temperature, while in the Zongkong catchment, the
relation between annual runoff, temperature and precipitation variations
was found to be complicated. Excluding the effect of the precipitation,
the time delay between the daily discharge peaks from Glacier No.1 and
the maximum temperature was 0-5 h.