Abstract
Glaciers located in the Qilian Mountains are rapidly retreating and thinning due to climate change. The current understanding of small glacier mass balance changes under a changing climate is limited by the scarcity of in situ measurements in both time and space as well as the resolution of remote sensing products. Unmanned aerial vehicles (UAVs) provide an unparalleled opportunity to track the spatiotemporal variations in glacier extent at a high resolution and the changing glacier morphological features related to glacial dynamics. Five measurements were performed on the Ningchan No. 1 (NC01) glacier in the Qilian Mountains between 18 August 2017 and 13 August 2020. The glacier changes displayed in the digital orthophoto maps (DOMs) and digital surface models (DSMs) show a 7.4 ± 0.1 m a−1 retreat of the terminus of NC01, a mass balance of −1.22 ± 0.1 m w.e. a−1 from 2017 to 2020, and a maximum surface velocity of 3.2 ± 0.47 m from 18 August 2017 to 26 August 2018, which clearly show consistency with stake measurements. The surface elevation change was influenced by the combined effects of air temperature, altitude, slope, and surface velocity. This research demonstrates that UAV photogrammetry can greatly improve the temporal and spatial resolution of glaciological research.
Highlights
The retreat of mountain glaciers around the world is clearly a sign of global climate change [1]
Five Unmanned aerial vehicles (UAVs) surveys of the entire NC01 glacier region were performed on 18 August 2017, Five UAV surveys of the entire NC01 glacier region were performed on 18 August
The results showed that the mean surface velocity for NC01 was 1.21 ± 0.47 m and 1.79 ± 0.47 m from 18 August 2017–26 August 2018 and 18 August 2017–26 August 2018, respectively (Figure 7)
Summary
The retreat of mountain glaciers around the world is clearly a sign of global climate change [1]. Glaciers provide water for irrigation, power generation, sanitation, and religious activities for large populations and are important parts of rivers in High Mountain Asia (HMA) [2,3,4]. A continuous negative mass balance results in the decrease in the amount of ice in these mountain ranges [5,6,7,8]. Monitoring glacier extent, mass balance, and surface velocity are critical to understanding how climate perturbations affect glaciers [11]. Studies have shown that due to the large number of small glaciers, the impact of their changes is much greater than expected [12]
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