Debris flow processes on lateral moraines of mountain glaciers (analytical review)

As a result of climate change there have been high rates of degradation of mountain glaciers in recent years. During deglaciation in the territories previously occupied by glaciers, moraines of various morphogenetic types remain deposited by them, connected with massifs of glacial-colluvial and other deposits. The most actively involved in debris flow processes are massifs of terminal moraines with extended steep ledges, on which debris flow cuts and furrows develop. Much less often, debris flow original sites are formed on lateral moraines, but debris flows can reach catastrophic proportions. The analysis of publications and of multi-time satellite images revealed data on the formation of debris flow original sites of various types in the areas of lateral moraines of mountain glaciers, pockets of lateral moraines filled with slope and glacial deposits, as well as lakes and streams inside them. Similar debris flow original sites have been characterized for the Central Caucasus, the Andes, the Hindu Kush, the Himalayas and Tibet. The largest debris flow disasters with original sites in areas of lateral moraines were outbursts of Palcacocha lakes in Peru in 1941 and Chorabari in India in 2013 with a death toll of up to 6054, as well as the outburst of South Lhonak Lake in Sikkim (India) in 2023. In areas of lateral moraines of valley glaciers connected with moraine pedestals of former tributary glaciers, the volume of mass transport of debris flows can reach 6.5 million m3 (lateral moraine of the Gangotri glacier in the Himalayas in 2017). The progress of debris flow processes on lateral moraines of mountain glaciers must be taken into account when developing mountain territories both in areas near lateral moraines and at a considerable distance from them.