Abstract
ABSTRACTUsing in-situ measured data from Qiyi Glacier, in combination with meteorological and run-off data from stations, a distributed degree-day model was developed for 631 investigated glaciers in the Beida River catchment to explore glacier mass change and its effect on streamflow. The results showed that the average mass balance was −272 ± 67 mm w.e. a−1, with an ice loss of 3.99 Gt during 1957–2013. Assuming a continuous linear trend, equilibrium line altitude rose by 242 m. Compared with morpho-topographic variables, climatic control is a more important factor affecting glacier change. Mass-balance sensitivity to air temperature was −239 mm w.e.°C−1a−1, while to precipitation it was +1.1 mm w.e. mm−1a−1. That is, a 210 mm increase in precipitation would be needed to compensate for the net mass loss induced by an air temperature increase of 1°C. Average annual glacier meltwater runoff was 1.51 × 108m3from 1957 to 2013, accounting for 15.2% of surface runoff. The time series of meltwater runoff changed abruptly in 2000, and its contribution to surface runoff increased from 13.9 to 20.4%.
Highlights
Mountain glaciers are the water towers of the world (Viviroli and others, 2007)
T where B is the glacier mass balance; f (f = 0.076) is the fraction of refreezing meltwater that is calculated by a multilevel snowmelt model (Yang and others, 2013); m is the ablation water equivalent of ice and snow; Ps is the accumulation which is equal to solid precipitation; and t is the selected period
The simulated and observed average mass balances were, respectively, −264 and −250 mm w.e. a−1, with a relative error of 5.7%, and the relative error reduced to 0.7% after 2006/07
Summary
Only covering ∼3% of the earth’s total glacierized land area (Meier, 1984; Arendt and others, 2002), small glaciers and ice caps (excluding the Antarctic and Greenland ice sheets) play an important role in assessing and predicting sea level change on decadal to centurial timescales (Oerlemans and Fortuin, 1992). Small glaciers have a shorter response time to climate change than the large ice sheets of Greenland and Antarctica, and their contribution may be even more if the climate continues to warm (Oerlemans and Fortuin, 1992). In contrast to variations in glacier length or area, variations in mass balance and equilibrium line attitude (ELA) are direct responses to glacier mass and climate change (Bolch and others, 2012)
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