Mudflow danger of periglacial lakes in the Elbrus region

摘要

Periglacial lakes of high mountains often become the center of the large mudflows formation. The purpose of this studywas to analyze the mudflow danger of periglacial lakes in the Elbrus region. The analysis was performed on the basis offield researches, interpretation and processing of PLEIADES satellite images and SPOT-6.The interpretive signs ofmudflow danger were revealed in the high mountains and a scale of mudflow risk was created on the basis of theidentified interpretive signs. Special attention was paid to Upper Bashkarinsky Lake, the breakthrough of which caused alarge mudflow in September 2017. According to the analysis of satellite images, we can conclude that the mudflow wasnot instantaneous, but occurred within a few hours, and this confirms the safety of Lower Bashkarinsky Lake. Intensiverainfall contributed to the blurring of the surface moraine on the glacier and then the ice itself. According to the satelliteimage the area of Upper Lake before the mudflow was 87 718 m~2, and after the mudflow – 27 608 m~2. Thus, the lakearea decreased by 60 110 m~2. Most of the periglacial lakes in the upper reaches of the Baksan river valley are located ataltitudes from 2400 to 3400 m, the maximum water volumes are concentrated in Lakes Syltrankel, Bashkar, Donguz-Orun, which are also potential mudslides and require long-term scientific monitoring.