Abstract
AbstractThis study deploys RTK-GNSS in 2012, TLS in 2015 and UAV in 2018 to monitor the changes of Urumqi Glacier No. 1 (UG1), eastern Tien Shan, and analyzes the feasibility of three technologies in monitoring the mountain glaciers. DEM differencing shows that UG1 has experienced a pronounced thinning and mass loss for the period of 2012–18. The glacier surface elevation change of −0.83 ± 0.57 m w.e. a−1 has been recorded for 2012–15, whereas the changes of glacier tongue surface elevation in 2015–18 and 2012–18 were −2.03 ± 0.95 and −1.34 ± 0.88 m w.e. a−1, respectively. The glacier area shrunk by 0.07 ± 0.07 × 10−3 km2 and the terminus retreat rate was 6.28 ± 0.83 m a−1 during 2012–18. The good agreement between the glaciological and geodetic specific mass-balances is promising, showing the combination of the three technologies is suitable to monitor glacier mass change. We recommend application of the three technologies to assess each other in different locations of the glacier, e.g. RTK-GNSS base stations, ground control points, glacier tongue and terminus, in order to avoid the inherent limitations of each technology and to provide reliable data for the future studies of mountain glacier changes in western China.
Highlights
Glaciers are recognized as one of the best indicators of climate variabilities, and feed many rivers in High-Mountain Asia (Immerzeel and others, 2010)
The survey accuracy about RTK-GNSS can reach the resolution in centimeters, and glacier surface elevation was obtained through dense points coverage
The results show that the correlation coefficient between them is 0.6 and the RTK-GNSS_DEM surface elevation is greater than the DinSAR_DEM surface elevation (Zhang and others, 2017)
Summary
Glaciers are recognized as one of the best indicators of climate variabilities, and feed many rivers in High-Mountain Asia (Immerzeel and others, 2010). Under a recent warming climate, mountain glaciers are losing mass. They are thinning and shrinking, and their tongues are receding. The annual shrinkage rate of area and ice volume in the Tien Shan were 0.7 and 0.83% a−1, respectively, and the mass loss increased by 27% with the increasing temperature over the past five decades (Farinotti and others, 2015). Glaciers in the Tien Shan have experienced continuous mass loss and area shrinkage during the past few decades. These changes can increase runoff in the short term, but may reduce the total runoff on long-term scales (Huss and Hock, 2018). Glacier changes in the Tien Shan have been contributing to a reduced runoff since the mid-1990s (Deng and others, 2018), which reflects the regulate mechanism of glaciers on water resources in the basin
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