Glacier changes and their impact on water resources in the Qilian Mountains, High Mountain Asia, 1970s to2020

Abstract

<p>The Qilian Mountains, located along the northeastern margin of the Tibetan Plateau, are in a transitional zone of climate types. Changes in glacier runoff in this region are important for the availability of water resources in arid regions of Northwest China. Combining multi-period remote sensing images and historical data, the distribute and changes in the area of glaciers in the region were updated and the changes in the glacier surface elevation were determined using geodesy methods. The glacier mass balance and glacier meltwater data were reconstructed using the glacier mass balance model. A continuous and accelerating shrinkage indicated substantial area loss between the 1970s and 2020 (516.89 km<sup>2</sup>, ~26%) and glacier thinning of -0.37±0.04 m a<sup>-1</sup> between 2000 and 2014 were identified. In general, glaciers in the eastern Qilian Mountains are less distributed and retreat faster, whereas those in the western Qilian Mountains are more distributed and retreat relatively slowly. The glacier mass balance of each basin in the Qilian Mountains showed an increasingly negative trend. However, due to the shrinking in glacier area and increasing in precipitation, the contribution of glacial meltwater to river runoff turns to decreasing trend around 2000. As the glaciers continue to retreat, the glacier regulation is becoming weakening, which is alarming, with respect to future changes in runoff and related disasters.</p>