Morphometric Characteristics of the Watershed Relief of the Velykyi Adzhalyk Liman (Black Sea)

Problem statement. The current state of the Velykyi Adzhalyk Liman is determined by the physico-geographical conditions of its basin and the adjacent part of the Black Sea, which are shaped by its transitional position between land and sea. A review of scientific publications has shown that the relief and morphometric characteristics of the watershed of the Velykyi Adzhalyk Liman are less studied compared to the hydrological elements of the water masses. Investigating the watershed relief is essential for understanding morpholithogenetic processes within the system of interactions among land, estuarine water bodies, and the sea, which are integral to the coastal systems of the northwestern Black Sea region. Given that relief is an equally important component of geosystems, its study is inseparable from the analysis of the landscape cover of the territory. Data & Methods. The study was conducted using topographic maps of the General Staff at a scale of 1:100,000. The determination of geomorphometric parameters was based on the AW3D30 Digital Elevation Model (DEM). Field surveys were also carried out. According to Tobler (1987), the scale of geomorphological maps produced using the DEM data corresponds to 1:60,000 – 1:100,000, which falls within the category of medium-scale geomorphological mapping. The evaluation of morphometric characteristics of the relief in the basin of the Velykyi Adzhalyk Liman was conducted using a combination of geomorphological (Kravchuk, 2006) and geomorphometric (Geomorphometry, 2009) methods. Calculations and mapping of morphometric indices were performed using the open-source GIS software SAGA v. 9.0.0. In this study, slope classifications appropriate for lowland regions were adopted. Slope aspect was determined using eight rhumbs. Indicators of dissection density and depth were calculated for 500 × 500 m grid cells. Results. The study of the morphometric characteristics of the watershed relief of the Velykyi Adzhalyk Liman revealed significant spatial variability, driven by both historical development and present-day dynamics. Morphometric parameters such as dissection density and depth differ considerably among the upper reaches, the middle section, and the coastal zone of the liman. Spatial analysis of morphometric attributes across the watershed indicated variations depending on elevation and distance from the water body, particularly in slope gradients. The aspect and planimetric shape of slopes exhibit the most complex spatial distributions, influenced by the general structure and historical evolution of the territory. Thus, the contemporary relief of the Velykyi Adzhalyk Liman watershed is composed of geomorphosystems of various ranks and origins, including fluvial, coastal, and slope-related systems. These geomorphosystems interact with one another, and their current dynamics are reflected in the spatial distribution of morphometric characteristics across the watershed.