Water Resources

Changes in the hydrological regime of the Ural River basin, associated with flow regulation and regional climate features, leads to the deterioration of many floodplain water bodies. Many oxbow depressions and lakes, which are habitats and spawning grounds for local fish species, lose their hydraulic connection with the main river channel, dry up and become overgrown with aquatic vegetation. The flooding duration for spawning grounds of various types largely determine the abundance and diversity of the local ichthyofauna in the floodplane lakes. Low spring floods in the period 2008–2023 became the main factor in the functional changes of floodplain water bodies, in which the frequency and duration of their connection with the main river channel decreased. Based on the data of ichthyological and hydrological field campaigns of 2022–2023, carried out in the valley of the middle reaches of the Ural River, including the lower section of the Sakmara River, the spawning grounds were classified based on their morphology and flooding conditions. The examination of the species and quantitative composition of fish in thirty floodplain water bodies made it possible to assess the influence of the frequency of their connection with the main river channel during spring floods on the total number of individuals and the species composition of fish. These indicators can be taken into account when planning hydraulic engineering measures for the aquatic environment rehabilitation.

The fluorine distribution in the waters of the Rybinsk Reservoir, its tributaries, and groundwater in coastal areas was studied using the direct potentiometry method. Low fluorine content was found in all explored water bodies with an average value of 0.13±0.03 mg/L. Surface waters (reservoir and its tributaries) are characterized by a close positive correlation of fluorine concentration with mineralization, while a similar relationship with the pH value is observed only under alkaline conditions at pH > 8. When using these waters for drinking purposes, it is recommended that the population consume additional digestible forms of fluorine to compensate for its deficiency relative to the sanitary and hygienic optimum.

The article is dedicated to the staff of the Water Problems Institute of the Russian Academy of Sciences who were veterans of the Great Patriotic War, and is timed to coincide with the 80th anniversary of the Victory. It compiles biographies of scientists who marched the frontline roads from Moscow to Berlin, survived the Siege of Leningrad, and in the post-war years worked at the Water Problems Institute, making significant contributions to the development of the country’s hydrology, hydrogeology, and water management. Based on archival data and colleagues’ recollections, their combat paths and professional achievements are presented.