Quantitative assessment of the terrain transformation in proglacial areas (the Djankuat River catchment case study, Caucuses)

Proglacial areas are extremely unstable and characterized by highly intensive geomorphic processes. In this study, we consider a typical proglacial area on the Caucuses – Djankuat river catchment. This research presents the first results for the complex monitoring of exogenic geomorphic process rates within the selected catchment. A repeated UAV survey for selected sites conducted in September 2019 and in August 2020 was the primary method. Also, high-resolution DEMs derived from stereo satellite images and the existing data obtained in field observations were used. It was determined that about 4122 ± 179 t yr-1 enters the glacier’s surface from the located above rockwalls due to rockfalls and avalanches, which corresponds to the erosion rate – 1.29 mm yr-1. The surface level averagely decreased by 0.48 m between surveys in the river valley just downstream from the glacier. The maximum losses were determined for the glacier front and buried ice outcrops, where values were -1.59 m (buried ice on the left valley side), -2.72 m (buried ice on the right valley side), -3.17 m (glacier front). The highest geomorphic intensity in the proglacial areas apparently associated with the rapid buried ice melting and occurs with a slight delay after the glacier retreat. Specific attention in proglacial areas should be paid to the quantitative assessment of extreme event consequences, which lead to main terrain transformations, sediment yield peak values, and, eventually, to total erosion. The study was supported by the Russian Science Foundation (project No. 19-17-00181).