Using UAV and satellite image data for analyzing the elevation change of debris-covered glaciers and its associated driving factors

In this paper, we aim to determine the interactions of debris-covered glacier elevation change with some glacial properties (including ice thickness, surface temperature, debris albedo, and supraglacial lakes) over the largest and the most dynamic glacier in Iran, Alamkouh Glacier, using the repeated acquisition of high-resolution remote sensing data and in-situ measurements during 2010–2018. First, we present the elevation change of Alamkouh glacier using digital elevation models (DEMs) derived from unmanned aerial vehicle (UAV) and LiDAR. Results revealed that on the whole glacier area, the LiDAR and UAV datasets achieved a highly consistent estimate of glacier elevation change at − 1.6 ± 0.2 m during 2010 and 2018. On the local scale, datasets revealed a clear constant between moderate elevation change of the two smaller flow units of the glacier (about − 0.48 ± 0.06 and − 0.37 ± 0.04 m) and significantly more negative elevation change in the main flow unit (− 2.5 ± 0.31 m). Results show that the elevation change of the Alamkouh glacier is jointly influenced by supraglacial lakes and the types of glacier cover. The regions where the rates of thinning are greatest coincide with the regions where the supraglacial lakes exist. In contrast, a weak relationship existed between the elevation change and glacier surface albedo and especially ice thickness. We observed a remarkable negative elevation change (− 6.3 m) of areas connected with supraglacial lakes in comparison with clean ice (− 3.1 m) and debris-covered (− 1.71 m) areas. It is proven that the quantity and area of the supraglacial lakes are the key to understanding the melting rate of the debris-covered glacier. Our observations infer the significant insulating function of debris cover on the Alamkouh glacier and highlight the effect of supraglacial lakes on enhancing glacier wastage.