Glacier mass variation and its effect on surface runoff in the Beida River catchment during 1957–2013

Abstract

ABSTRACT. Using in-situ measured data from Qiyi Glacier, in combination with meteorological and runoff 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 −1 a −1 , while to precipitation it was +1.1 mm w.e. mm −1 a −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 × 10 8 m 3 from 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%.

Mass Balance Variation and Associative Climate Drivers for the Dongkemadi Glacier in the Central Tibetan Plateau

“…The glacier equilibrium line altitude (ELA) is the boundary between the accumulation zone and ablation zone. The glacier mass balance and the ELA are highly linearly correlated (Wang et al, 2017). To investigate the relationship between the annual mass balance (mm w. e.) and ELA (100 m), we applied the function described by Braithwaite (1984):…”

“…In this context, glacial models play a vital role in reconstructing long‐term glacier mass balances as well as allowing for the analysis of causes related to mass balance change. For example, a number of studies have reconstructed mass balance series using the empirically based degree‐day approach over approximately five decades in the northern (Wang et al, ), southern (Caidong & Sorteberg, ), and central Tibetan Plateau regions (Gao et al, ), or by using physically based energy balance models, but only over the past two decades on Pamir (Zhu et al, ). Compared to the ] ?>degree‐day] ?> approach, the physical process‐based distributed surface energy balance model (DSEBM) can determine the most important atmospheric variables and water balance components both temporally and spatially as well as the key locations that should be monitored (Pellicciotti et al, 2004).…”

Spatial and temporal variations in mass balance of Qiyi Glacier in Qilian Mountains

“…1986/1987 年西北地区气候转型 [16] 以来，七一冰川末端逐年退缩，物质亏损严重，冰川零 平衡线海拔 (ELA) 持续上升。冰川的强烈消融同时造成了融水径流普遍增加。在北大 河流域，2000 年前后冰川融水对河流径流的补给贡献率从 13.9%增加到 20.4% [18] (mm w.e. ) 可由以下公式计算 [8] ：…”

“…式中：bi为第 i 个高度带的平均物质平衡 (mm w.e. ) ；si为第 i 个高度带的面积 (km 2 ) ；S 为七一冰川的总面积 (km 2 ) 。 在河西走廊地区，山区与平原区的气候变化存在差异性，相较而言，气温变化的空 间差异较小，而降水变化的空间差异较大 [22] 。因此，本研究选取距离冰川最近且与冰川 区气温降水变化相关性最好 [18] [23] ，1980s 物质平衡正负波动 [24] 到 21 世纪负平衡 [8,17] 的转变。根据文献中的物质平衡记 录，在 2011 年以前，七一冰川于 2005/2006 年出现观测以来的最大负平衡-955 mm w.e. [8] [8] 。为深入研究 21 世纪以来青藏高原不同区域 冰川物质平衡的空间差异，自北向南选取高原中东部物质平衡观测序列较长的三条冰 川与七一冰川进行对比 (图 5、表 3) ，其中乌鲁木齐河源 1 号冰川 (简称 1 号冰川) [25,26] 和小冬克玛底冰川 [8,27] 为大陆型，帕隆 94 号冰川 [8,26] [23,24] 中，普遍认为 9 月初是消融季向积累季的转折点，而近 5 年的观测表明，整个 9 月 份的冰川消融仍普遍发生，消融季末已延后至 9 月底。七一冰川物质平衡过程中 4-5 月和 9-10 月的物质平衡变化较为复杂，受到气温和降水的综合影响。如 2012 年 4 月、2013 年 5 月和 2014 年 10 月出现了持续强降雪天气，上述三个月出现较大正平衡。而 2012 年 9-10 图 5 青藏高原四条典型冰川的物质平衡序列…”

Modeling past and future variation of glaciers in the Dongkemadi Ice Field on central Tibetan Plateau from 1989 to 2050

“…However, sufficient input data for comprehensive modeling of glacier mass variation are available for a limited number of well-studied (and almost all small) glaciers on the TP; for example, No. 1 Glacier at the source of Urumqi River and Qiyi Glacier (Yao et al 2012;S. Wang et al 2017).…”