Quantifying glacial elevation changes in the central Qilian Mountains during the early 21^st century

Abstract

Glaciers in the central Qilian Mountains provide important water resources for the arid Hexi corridor and Qaidam Basin; however, changes in these glaciers interact with climate change. Twenty-four bi-static image pairs of TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) data, in addition to a Shuttle Radar Topography Mission-C/X band digital elevation model, and the technology of iterative differential synthetic aperture radar interferometry were used to carry out glacier elevation change analysis in the central Qilian Mountains in China during 2000–2014. Glacier elevation changed with an average rate of (−0.47±0.06) m yr⁻¹, while changes in elevation of (−0.51±0.06) m yr⁻¹ and (−0.44±0.06) m yr⁻¹ were found in the northern (including the Zoulangnan, Tuolai, and Tuolainan mountains) and southern (including the Shulenan and Hark mountains) regions, respectively. Summer mean temperature has risen by 0.51°C (10 yr)⁻¹ in the northern region and 0.48°C (10 yr)⁻¹ in the southern region during 1989–2014; however, the change in amplitude of annual precipitation was 2.69 mm yr⁻¹ in the northern region and 4.77 mm yr⁻¹ in the southern region for the same period. These changes can be ascribed as major driving factors for the differences in the changes in glacial elevation in the northern and southern regions. Four types of glaciers existed in the region when considering the change in elevation of the glacial tongue and variation in the position of the glacial terminus: surging, advancing, intensively retreating, and slightly retreating glaciers. If elevation decreased more than 20 m on the part of glacier tongue, the glacier terminus position had commonly retreated more than 100 m.