ИСТИНА

Radio-echo sounding (RES) is a widely used method to assess glacier thickness and bedrock topography providing high (2–3 %) accuracy of measurements using ground-based or airborne radars. Reliable ice thickness assessments play important role in a number of glaciological objectives. Data on ice thickness are highly essential for glacier volume and runoff estimations as well as for modelling of future glacier lakes formation what is crucial for natural hazard assessments. However direct ice thickness measurements are rare due to high costs and time consuming. The Central Caucasus is one of glacierized mountain regions with lack of direct ice thickness measurements. Such data is available for several glaciers from more than 1.7 thousand located in these mountains. Here we present new detailed ice thickness dataset for two valley glaciers in the Central Caucasus from recent field campaigns. During summer 2017 radar ice thickness measurements were performed for Bashkara and Bezengi glaciers situated in Adyl-Su and Cherek catchments, respectively. Ice thickness and bedrock topography maps were compiled and ice volume was estimated. Bashkara is relatively small (3 km2 area and ~4 km long) valley glacier with 3 moraine-dammed lakes in front of its terminus was covered by 8 km of radar profiles across 1.2 km2 area of its snout. Maximum and mean measured ice thickness reaches 217 and 109 m respectively. Modelling of bedrock overdeepings revealed no serious “lakes” underneath modern glacier terminus which can pose a danger. Bezengi, the largest glacier in the Caucasus, was covered by almost 60 km of radar profiles totally covering 9 km length and 7.2 km2 area snout. Obtained ice thickness data revealed the thickest ice measured in the Caucasus – up to 425 m and 197 as mean value. Ice volume of investigated part of Bezengi glacier reaches 1.4 km3. This research was supported by RFBR grant № 16-05-45045.