BARSEM DEBRIS FLOW DISASTER IN THE PAMIRS IN 2015 AND ITS ANALOGUES IN THE CENTRAL CAUCASUS

Abstract

we characterize specific features of formation and consequences of the debris flow disaster occurred on the Barsemdara River in the Gunt River valley (Barsem village, Gorno-Badakhshan Autonomous Region, Tajikistan) on July 16–24, 2015. The paper presents the data on debris flow events with similar formation mechanism that took place in the following river valleys: Adyr-Su in 1940, 1983 and 2011, Tyutyun-Su in 1953, Khaznidon in 1975 et al. A common feature of the considered debris flows is the confinedness of debris flow site to special glacial accumulation forms — moraine pedestals containing a large amount of buried ice. Due to large-scale and long-term debris flow processes moraine pedestals take the shape of gullies. The largest example of considered landform is the debris flow gully (1 km-length) situated in the upper reaches of the Tyutyun-Su River in the Cherek Balkarskiy River basin (Central Caucasus). Similar debris flow processes were also observed in other mountain areas (Zaas River valley (Switzerland) in 1987, valley of the Ishkoman River left tributary (Pakistan) in 2018). Volumes of debris flow material carried out from moraine pedestals reach 1–5 million m3. In 2015 part of the Barsem village territory became covered with debris flow deposits and a dam was formed on the Gunt River above which is the Barsemkul dammed lake now. Places of possible debris flows such as Barsem disasters can be determined on the basis of glacial accumulation form analysis and identification of moraine pedestals in which the debris flow incisions are not yet developed.