Evolution of Erosional Badlands in the Eastern Black Sea Region During the Late Holocene

Abstract

This paper presents the results of geomorphological research conducted in the Mussera Upland (Western Abkhazia) in 2024. Based on morphometric analysis and geomorphological survey within the typical river basin (Ryapsh River basin), the topographical features of the upland were described in detail, and radiocarbon dating of alluvial deposits was performed. We found that the Mussera Upland is a typical humid badland with a dissection density of 3–4 km/km 2 . The formation of a low-order fluvial network begins here within a catchment area of approximately 0.01 km 2 . Within the dendritic catchment of the Ryapsh River, erosional slopes of varying steepness cover 94% of the total area, with only about 6% occupied by alluvial terraces in the valley floor (up to 1.5 m and up to 3.0 m above the riverbed). Both of these terraces were formed during the Holocene within the last thousand years: the low alluvial level formed no earlier than 570–670 cal yr BP, and the upper alluvial level in the Ryapsh River valley was formed about 810–960 cal yr BP. The development of the Mussera badland is occurring with the leading role of erosional and slope processes (primarily landslides) under conditions of ongoing tectonic uplift. The forest cover of the area does not prevent slope denudation, but, instead, it often triggers it. The development of the badland is characterized by two opposing trends: over time, the ridges are lowered due to slope denudation; however the depth of dissection does not decrease due to ongoing tectonic uplift and active stream downcutting. In recent decades climate change has increased the frequency of extreme rainfall events, resulting in a noticeable rise in denudation rates.