Glacier change over the last century, Caucasus Mountains, Georgia, observed from old topographical maps, Landsat and ASTER satellite imagery

Abstract

Abstract. Changes in the area and number of glaciers in the Georgian Caucasus Mountains were examined over the last century, by comparing recent Landsat and ASTER images (2014) with older topographical maps (1911, 1960) along with middle and high mountain meteorological stations data. Total glacier area decreased by 8.1 ± 1.8 % (0.2 ± 0.04 % yr −1 ) or by 49.9 ± 10.6 km 2 from 613.6 ± 9.8 km 2 to 563.7 ± 11.3 km 2 during 1911-1960, while the number of glaciers increased from 515 to 786. During 1960-2014, the total ice area decreased by 36.9 ± 2.2 % (0.7 ± 0.04 % yr −1 ) or by 207.9 ± 9.8 km 2 from 563.7 ± 11.3 km 2 to 355.8 ± 8.3 km 2 , while glacier numbers decreased from 786 to 637. In total, the area of Georgia glaciers reduced by 42.0 ± 2.0 % (0.4 ± 0.02 % yr −1 ) between 1911 and 2014. The eastern Caucasus section had the highest retreat rate of 67.3 ± 2.0 % (0.7 ± 0.02 % yr −1 ) over this period, while the central part of Georgian Caucasus had the lowest, 34.6 ± 1.8 % (0.3 ± 0.01 % yr −1 ), with the western Caucasus intermediate at 42.8 ± 2.7 % (0.4 ± 0.03 % yr −1 ).

The Greater Caucasus Glacier Inventory (Russia, Georgia and Azerbaijan)

“…The study of glaciers in the Caucasus began in the first quarter of the 18th century, in the works of Georgian scientist Vakhushti Bagrationi (Tielidze, 2016); subsequently there were many early expeditions and glacier photographs covering the time period 1875-1906(Solomina et al, 2016. Studies focused on glacier mapping began when Podozerskiy (1911) published the first inventory of the Greater Caucasus glaciers, based on large-scale military topographical maps (1 : 42 000) from 1881 to 1910, identifying 1329 glaciers, with a total area of 1967.4 km 2 (Kotlyakov et al, 2015).…”

“…Studies focused on glacier mapping began when Podozerskiy (1911) published the first inventory of the Greater Caucasus glaciers, based on large-scale military topographical maps (1 : 42 000) from 1881 to 1910, identifying 1329 glaciers, with a total area of 1967.4 km 2 (Kotlyakov et al, 2015). Detailed analysis of these early data showed some defects in the depicted shape of the glaciers and in particular those in inaccessible valley glaciers (Tielidze, 2016). Reinhardt (1916Reinhardt ( , 1936) noted Podozerskiy's errors in compiling a new catalogue for some glacial basins of the Greater Caucasus region (Tielidze, 2017).…”

“…This includes some errors as temporary snowfields were misinterpreted as glaciers (Gobejishvili, 1995;Tielidze, 2016), and the catalogue data sets contained glacier parameters but not outlines. As the USSR catalogue and 1960s large-scale (1 : 50 000) topographic maps were based on the same aerial photographs, we have used both data sets in this article for a more comprehensive comparison.…”

Supraglacial debris cover assessment in the Caucasus Mountains, 1986-2000-2014

“…Technical errors can be mostly ignored if the satellite image has been accurately orthorectified, which was the case for Landsat images provided by USGS (e.g. Tielidze, 2016;Tielidze and Wheate, 2017). Interpretation errors mostly depend on how 'glacier' is defined for the purposes of inventory compilation, and thus are difficult to evaluate.…”

Late Pleistocene and Holocene Glacier Extent in the Georgian Caucasus

“…The relief of the Eastern Caucasus with its morphological and morphometric properties is behind the Central Caucasus, resulting in, together with the climatic factors, the small scales of glaciation [26] both, today and in the entire Upper Quaternary and Holocene. As we have seen above, the modern glaciers are associated with the individual high-elevated massifs.…”