Hydrological and hydrochemical studies of reservoirs in the Western Manych valley

Studies of the hydrological and hydrochemical characteristics of reservoirs in the Western Manych valley have been carried out. Based on the materials of the expedition of July-August 2023, an assessment of the spatial distribution of the total mineralization of water, ionic composition, including information on classes and types of waters according to the classification of O.A. Alekin, values of the hydrogen index, oxygen regime and concentration of total suspended matter was carried out. Special attention is paid to the eastern section of the Proletarskoe Reservoir. An assessment of the interannual change in water mineralization in Lake Manych-Gudilo is given and the changes in the ratio of the main ions are considered. Information is provided on the flow rates of the Egorlyk River and the Kalaus River entering the eastern compartment of the Proletarskoe Reservoir. The studied water bodies are characterized by a wide range of variability in mineralization and ionic composition. Mineralization values range from 1.6 to 161 g/l. When moving from the mouth to the source of the Western Manych, the water changes from sodium sulfate of the second type to sodium chloride of the second and third types. Only after the confluence with the Egorlyk River on the left and the Don waters entering from the irrigation systems on the right it becomes sulfate-sodium of the second type again. Currently the mineralization of the lake part of the eastern compartment of the Proletarskoe Reservoir is twice as high as in the waters of the World Ocean. The presence of two frontal zones in the mixing zone of the waters of the Egorlyk River and Lake Manych-Gudilo has been confirmed. According to the hydrochemical characteristics (class of waters), two regions are distinguished: the western freshwater, or “river”, and “lake”, including the mixing zone and Lake Manych-Gudilo itself. It is significant that by ionic composition at the time of the study, the “lake” waters were closer to the water of the Caspian Sea than the Aral Sea or the World Ocean.