Škilietų ir Tabaliukų ežerų morfometrija
Morphometry of Škilietai and Tabaliukai Lakes

Summary/Abstract: Depth measurements of Škilietai and Tabaliukai Lakes (located in the Baltic Uplands, Aukštadvaris regional park, Lithuania) were taken in January and February of 2019. At the same time, the shorelines of the lakes were revised. Measurements were made from ice; measurement density varies from 34 to 46 spots per hectare. Depth measurement accuracy up to 0,05 m in Tabaliukai Lakes and Lake Škilietai I, up to 0,1 m in Lake Škilietai II. Accuracy of spot coordinates and water surface elevation measurement using GNSS receiver Topcon Hiper SR up to 1–2 cm. Later, detailed (0.50 x 5 m) digital lake bottom models (DEM) were developed, bathymetric plans of the lakes were created, the main morphometric features were calculated, the boundaries and area of the lake catchments were defined, and the physical-geographical characteristics of the lakes were described based on field observations and various data. Škilietai and Tabaliukai are small and closed groups of lakes (each group consists of 2 lakes) of glaciokarst origin. Despite small surface area (1.7–5.3 ha) the lakes are quite deep (9.8–18.5 m). Differences in the surface area and volume (77.8–436.3 thousand m3) of lakes are due to large differences in catchment areas. The shape of the lakes is remarkably regular, close to the circle. Tabaliukai Lakes usually are connected through bog lag and share the same water level, meanwhile, the water level in Škilietai Lakes differs on average by ~0.20 m. During the observation period (from spring of 2018 to May of 2020), the amplitude of water level fluctuations in Škilietai Lakes reached 0,41–0,48 m, and in Tabaliukai Lakes 0,67 m. The differences in the area and volume of the studied lakes are mainly due to the very different area of the lake catchments.

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