Bedia Landslide Site in Eastern Abkhazia

The article presents the results of geomorphological studies of the area of widespread landslide processes in the upper reaches of the Okhodzha River basin (right tributary of the Okum River, Black Sea basin). The characteristics of the geological and geomorphological conditions and factors that contributed to the occurrence of a large landslide in January 2021 are given. It has been established that the main type of landslides within the Bedia site are landslide flows developing along the roof of Eocene and Oligocene (Khadum horizon and Maikop Formation) claystones. The thickness of landslide bodies ranges from to 34–78 m. The slope cover is mainly subject to displacement, including the bodies of previous landslides. It is shown that the main condition determining the development of landslide processes is the position of the Bedia landslide site at the junction of the water-logged carbonate rocks of Cretaceous age exposed along the Southern macroslope of the Greater Caucasus, and denuded foothills composed of the Paleogene clayey rocks. The landslides are triggered by prolonged precipitation and facilitated by the coincidence of the slope and the bedrock dip direction on the left slope of the Okhodzha River valley. Due to the large-scale development of landslide processes accompanied by erosion, an erosion-landslide badland was formed on the left bank of the Okhodzha River. The most unstable areas, not recommended for land-use due to periodic landslide movements, are the slopes of small valleys – left tributaries of the Okhodzha River, as well as their wide bottoms filled with landslide deposits. According to the main features of the geological and geomorphological structure, the studied area is similar to the Novoafonsky, Eshersky and Macharsky landslide areas previously described in scientific literature. Economic development of these territories should include not only constructive measures to protect against landslides (retaining walls, artificial terracing, etc.), but also the installation of drainage systems to reduce the water saturation of slope deposits and the water content at the base of the slope.

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