Transboundary Water Exchange in the Don River Basin

Different types of water exchange across state (as of the end of February 2022), administrative and natural borders in the Don River basin are considered. The indicators of atmospheric moisture transfer and wind movement of snow, water runoff across the boundaries of forest-steppe and steppe zones and the boundaries of individual landscapes are given. Most of the water is transported across all boundaries in the atmosphere. River runoff is only 4% of the value of atmospheric moisture transfer; 42% of the total annual runoff flows from the forest-steppe to the borders of the steppe zone, 39% of the flood runoff and 55–65% of the minimum summer-autumn and winter runoff. The exchange of river water between individual subjects in the Russian part of the Don River basin has been determined. There is a significant improvement in the water availability of the regions, taking into account the transit flow. The transfer of chemicals with water is considered. The features of the formation of diffuse runoff of biogenic elements in different landscapes are revealed. The results of a comparative analysis of the dynamics of the content of pollutants in the wastewater of Rostov, Voronezh, and Lipetsk oblasts for 1995–2018 period are presented. The impact of local and transit wastewater on the quality of water resources of Rostov oblast is assessed. The features of transboundary water exchange in connection with climate changes and economic activity that have occurred over the past decades are revealed. Mainly due to climatic changes, river runoff on the Lower Don has significantly decreased–by an average of 20%. The role of the surface component of runoff in the movement of water together with pollutants across administrative and natural borders has significantly decreased, while the role of the underground component, on the contrary, has increased. The ways of solving the main problems caused by transboundary water exchange are proposed.