摘要： The Karakoram Mountains are well known for their widespread surge-type glaciers and slight glacier mass gains. On the one hand, glaciers are one of the sensitive indicators of climate change, their area and thickness will adjust with climate change. On the other hand, glaciers provide freshwater resources for agricultural irrigation and hydroelectric generation in the downstream areas of the Shaksgam River Basin (SRB) in western China. The shrinkage of glaciers caused by climate change can significantly affect the security and sustainable development of regional water resources. In this study, we analyzed the changes in glacier area from 2000 to 2016 in the SRB using Landsat TM (Thematic Mapper)/ETM+ (Enhanced Mapper Plus)/OLI (Operational Land Imager) images. It is shown that the SRB contained 472 glaciers, with an area of 1840.3 km2, in 2016. The glacier area decreased by 0.14%/a since 2000, and the shrinkage of glacier in the southeast, east and south directions were the most, while the northeast, north directions were the least. Debris-covered area accounted for 8.0% of the total glacier area. We estimated elevation and mass changes using the 1 arc-second SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model) (2000) and the resolution of 8 m HMA (High Mountain Asia) DEM (2016). An average thickness of 0.08 (±0.03) m/a, or a slight mass increase of 0.06 (±0.02) m w.e./a has been obtained since 2000. We found thinning was significantly lesser on the clean ice than the debris-covered ice. In addition, the elevation of glacier surface is spatially heterogeneous, showing that the accumulation of mass is dominant in high altitude regions, and the main mass loss is in low altitude regions, excluding the surge-type glacier. For surge-type glaciers, the mass may transfer from the reservoir to the receiving area rapidly when surges, then resulting in an advance of glacier terminus. The main surge mechanism is still unclear, it is worth noting that the surge did not increase the glacier mass in this study.
摘要：Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications; however, detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains remain lacking. Burqin Glacier No. 18 is a northeast-orientated cirque glacier located on the southern side of the Altay Mountains. This study used PulseEKKO® PRO 100A enhancement ground-penetrating radar (GPR) to survey the ice thickness and volume of Burqin Glacier No. 18 in summer 2018. Together with GPR surveying, spatial distributed profiles of the GPR measurements were concurrently surveyed using the real-time kinematic (RTK) global navigation satellite system (GNSS, Unistrong E650). Besides, we used QuickBird, WorldView-2, and Landsat TM to delineate accurate boundary of the glacier for undertaking estimation of glacier ice volume. GPR measurements revealed that the basal topography of profile B1-B2 was flat, the basal topography of profile C1-C2 presented a V-type form, and the basal topography of profile D1-D2 had a typical U-type topographic feature because the bedrock near the central elevation of the glacier was relatively flat. The longitudinal profile A1-A2 showed a ladder-like distribution. Glacier ice was thin at the terminus and its thickness increased gradually from the elevation of approximately 2620 m a.s.l. along the main axis of the glacier tongue with an average value of 80 (±1) m. The average ice thickness of the glacier was determined as 27 (±2) m and its total ice volume was estimated at 0.031 (±0.002) km3. Interpretation of remote sensing images indicated that during 1989–2016, the glacier area reduced from 1.30 to 1.17 km2 (reduction of 0.37%/a) and the glacier terminus retreated at the rate of 8.48 m/a. The mean ice thickness of Burqin Glacier No. 18 was less than that of the majority of other observed glaciers in China, especially those in the Qilian Mountains and Central Chinese Tianshan Mountains; this is probably attributable to differences in glacier type and climatic setting.