Glacial Lake Inventory and GLOF Hazard Assessment in Caucasus Region

Glacial lakes in the Greater Caucasus may present a significant glacial lake outburst flood (GLOF) hazard to mountain communities and rapidly growing tourism infrastructure. However, their distribution and hazard level have not been systematically assessed. This study aims to create the first multi-temporal inventory of glacial lakes in the Greater Caucasus and to evaluate their GLOF hazard. We mapped lakes above 2000 m a.s.l. with surface areas of at least 500 m2 using Sentinel-2 (2018, 2025) and Landsat-5 and Landsat-7 (2000) imagery, Soviet topographic maps, field bathymetric surveys, and published historical records. A total of 1384 lakes above 2000 m a.s.l. and with surface areas of at least 500 m2 were identified. Of these, 973 were classified as extraglacial (water bodies of glacial origin situated in currently glacier-free valleys), while the remaining 411 lakes (supraglacial, proglacial, and periglacial) were subjected to a structured GLOF hazard assessment. Periglacial lakes dominate the inventoried types (90%), whereas proglacial lakes, though fewest in number, represent the most dynamic and hazard-relevant category. The total area of glacial lakes (excluding extraglacial lakes) is 5.05 ± 0.79 km2, and the area of extraglacial lakes is 14.37 ± 1.96 km2. Sixteen new lakes have appeared since 2018, concentrated predominantly in the Central Caucasus. Hazard assessment was carried out using a six-criterion scoring system based on dam material, distance to the glacier, lake area, presence of surface outflow, lake age, and shore collapse hazard. Of the 411 assessed lakes, 19% were classified as high-hazard, 53% as moderate-hazard, and 28% as low-hazard. The results provide a baseline for environmental monitoring, hazard management, and risk-reduction planning in the Caucasus.