Lateral moraine failure in the valley of the Djankuat Catchment (Central Caucasus) and subsequent morphodynamics

Kedich, A.; Kharchenko, S.; Tsyplenkov, A.; Golosov, V.

Авторы: Kedich A., Kharchenko S., Tsyplenkov A., Golosov V.
Журнал: Geomorphology
Том: 441
Год издания: 2023
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Номер статьи: 108896
DOI: 10.1016/j.geomorph.2023.108896
Аннотация: Moraine failures are severe events in proglacial areas that lead to major surface changes. On July 1, 2015, alateral moraine collapsed within the 9.1 km2 glacierized Djankuat Catchment in the Northern Caucasus. Thisstudy quantifies the surface changes over a 7-year period after the collapse and proposes the main event triggersusing hydrometeorological measurements and remote sensing data. Digital Elevation Models (DEMs), derivedfrom Unmanned Aerial Vehicle (UAV) surveys and satellite images for the 2010–2022 period, were used to estimate erosion/deposition associated with the event and further surface changes in several zones: the breach, thefan, the headward erosion area and gully erosion on lateral moraine slopes. The failure occurred due to anextreme precipitation event (7-day cumulative sum: 227 mm, 24 h prior: 60 mm), simultaneous snowmelt withinthe whole upstream catchment, and continuous positive temperatures. During the 2015 event, approximately200,000 m3 of material was instantly eroded, corresponding to a surface lowering of 1.91 m a− 1 (over 52,227m2). Only 25 % of the eroded material redeposited on the fan. Later in 2017–2019, the breach underwentinfilling with a 10 m deposition layer in the bottom (net change ca. 14,600 m3), while the stream in theheadward erosion area continued to incise (ca. − 12,900 m3). From 2019 to 2022, the dynamics decreased, and apositive sediment budget was assessed for all zones except the intensive local erosion on the fan in 2021–2022(ca. − 15,200 m3). Gully changes suggested a constant erosion of 90–100 mm a− 1. Based on daily rainfallmeasurements for the 2008–2022 period, we proposed a 3-day and prior 15-day cumulative precipitationthreshold that outlines major erosional events in the Djankuat River valley. A cumulative 3-day precipitation of100 mm could be a sufficient but not necessary condition since some significant sediment export was recordedbelow that threshold.
Добавил в систему: Голосов Валентин Николаевич

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Lateral moraine failure in the valley of the Djankuat Catchment (Central Caucasus) and subsequent morphodynamicsстатья

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