Abstract
The Shaksgam Valley, located on the north side of the Karakoram Mountains of western China, is situated in the transition zone between the Indian monsoon system and dry arid climate zones. Previous studies have reported abnormal behaviors of the glaciers in this region compared to the global trend of glacier retreat, so the region is of special interest for glacier-climatological studies. For this purpose, long-term monitoring of glaciers in this region is necessary to obtain a better understanding of the relationships between glacier changes and local climate variations. However, accurate historical and up-to-date glacier inventory data for the region are currently unavailable. For this reason, this study conducted glacier inventories for the years 1970, 1980, 1990, 2000 and 2014 (i.e., a ~10-year interval) using multi-temporal remote sensing imagery. The remote sensing data used included Corona KH-4A/B (1965–1971), Hexagon KH-9 (1980), Landsat Thematic Mapper (TM) (1990/1993), Landsat Enhanced Thematic Mapper Plus (ETM+) (2000/2001), and Landsat Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) (2014/2015) multispectral satellite images, as well as digital elevation models (DEMs) from the Shuttle Radar Topography Mission (SRTM), DEMs generated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images (2005–2014), and Advanced Land Observing Satellite (ALOS) World 3D 30 m mesh (AW3D30). In the year 2014, a total of 173 glaciers (including 121 debris-free glaciers) (>0.5 km2), covering an area of 1478 ± 34 km2 (area of debris-free glaciers: 295 ± 7 km2) were mapped. The multi-temporal glacier inventory results indicated that total glacier area change between 1970–2014 was not significant. However, individual glacier changes showed significant variability. Comparisons of the changes in glacier terminus position indicated that 55 (32 debris-covered) glaciers experienced significant advances (~40–1400 m) between 1970–2014, and 74 (32 debris-covered) glaciers experienced significant advances (~40–1400 m) during the most recent period (2000–2014). Notably, small glaciers showed higher sensitivity to climate changes, and the glaciers located in the western part of the study site were exhibiting glacier area expansion compared to other parts of the Shaksgam Valley. Finally, regression analyses indicated that topographic parameters were not the main driver of glacier changes. On the contrary, local climate variability could explain the complex behavior of glaciers in this region.
Highlights
Glaciers are key indicators of climate change and provide important freshwater resources [1]
Orthorectified Landsat series scenes (TM, ETM+ and Operational Land Imager and Thermal Infrared Sensor (OLI/TIRS)) (Table 1) and digital elevation models (DEMs) from the Shuttle Radar Topography Mission (SRTM), as well as mosaicked DEMs generated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo images acquired between 2005–2014 were used for generation of glacier inventories in 1990, 2000 and 2014
Additional Landsat scenes from 1993 (Landsat Thematic Mapper (TM)), 2001 (Landsat ETM+) and 2015 (Landsat OLI/TIRS) (Table 1) were used as complementary images during the digitization of the glacier outlines and to help differentiate seasonal fresh snow from permanent snow patches. 30 m spatial resolution SRTM and mosaicked ASTER DEMs were used to derive the geomorphometric parameters (GMP) such as slope, plan curvature and profile curvature, that are helpful for debris- covered glacier mapping [29,30]
Summary
Glaciers are key indicators of climate change and provide important freshwater resources [1]. The Shaksgam glaciers are one of the largest sources of glacial lake outburst floods in this region [4,5]. Except for publicly available glacier inventories such as the First Chinese Glacier Inventory (FCGI) [13], the Second Chinese Glacier Inventory (SCGI) [14], Glaciers_cci [15] and the Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM) glacier inventory [16], only two studies have investigated the glacier changes in the Karakoram region, which encompasses the Shaksgam Valley [8,17]. For the past period, both studies were only mapped the glacier terminus position changes (not the entire glacier outline) using multi-mission Landsat images and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images [8,17]. Two Corona KH-4A and 10 Corona KH-4B (acquisition time: 1965–1971, Table 1) images were used for generation of a glacier inventory for the year 1970
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
