Supra-glacial debris cover changes in the Greater Caucasus from 1986 to 2014

Tielidze, Levan G.; Bolch, Tobias; Wheate, Roger D.; Kutuzov, Stanislav S.; Lavrentiev, Ivan I.; Zemp, Michael

Knowledge of supra-glacial debris cover and its changes remain incomplete in the Greater Caucasus, in spite of recent glacier studies. Here we present data of supra-glacial debris cover for 659 glaciers across the Greater Caucasus based on Landsat and SPOT images from the years 1986, 2000 and 2014. We combined semi-automated methods for mapping the clean ice with manual digitization of debris-covered glacier parts and calculated supra-glacial debris-covered area as the residual between these two maps. The accuracy of the results was assessed by using high-resolution Google Earth imagery and GPS data for selected glaciers. From 1986 to 2014, the total glacier area decreased from inline-formula691.5±29.0 to inline-formula590.0±25.8 kminline-formula2 (inline-formula15.8±4.1 %, or inline-formula∼0.52 % yrinline-formula−1), while the clean-ice area reduced from inline-formula643.2±25.9 to inline-formula511.0±20.9 kminline-formula2 (inline-formula20.1±4.0 %, or inline-formula∼0.73 % yrinline-formula−1). In contrast supra-glacial debris cover increased from inline-formula7.0±6.4 %, or inline-formula48.3±3.1 kminline-formula2, in 1986 to inline-formula13.4±6.2 % (inline-formula∼0.22 % yrinline-formula−1), or inline-formula79.0±4.9 kminline-formula2, in 2014. Debris-free glaciers exhibited higher area and length reductions than debris-covered glaciers. The distribution of the supra-glacial debris cover differs between the northern and southern and between the western, central and eastern Greater Caucasus. The observed increase in supra-glacial debris cover is significantly stronger on the northern slopes. Overall, we have observed up-glacier average migration of supra-glacial debris cover from about 3015 to 3130 m a.s.l. (metres above sea level) during the investigated period.

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Tielidze, Levan G. / Bolch, Tobias / Wheate, Roger D. / et al: Supra-glacial debris cover changes in the Greater Caucasus from 1986 to 2014. 2020. Copernicus Publications.

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