ИСТИНА

The analysis of hydrometeorological network observations data made it possible to come to the conclusion about the impact of ongoing climate changes on the conditions of the formation of runoff and its intra-annual redistribution since the late 1970s. The reason for the changes in the ETR can be considered an increase in surface air temperature, which reduced the freezing of soils, changed the conditions of migration and infiltration of moisture in the aeration zone, which led to an increase in groundwater supply. Predicted changes in the conditions for the formation of runoff in the catchment area of the Don can have negative consequences for fisheries in the estuarine region and for the stabilization of the salinity of the Azov Sea. The combined influence of climatic and anthropogenic factors on the degradation of high water on the vast majority of rivers of the Don basin has been revealed. The task of this work is to assess the changes in spring runoff and the role of anthropogenic factors. Taking into account the total area of reservoirs 519.4 km2, irretrievable flow losses amount to 0.09 km3 per year, or 0.5% of the average annual flow of the Don, in the Kalach-on-Don formation. The decrease in runoff in high-water phases increases with the growth of the catchment area of the Don tributaries and depends on the number of reservoirs in their basin. The increase in the volume of runoff in low-water phases is directly proportional to the catchment area and the number of reservoirs. The results obtained indicate a significant contribution of reservoirs to the change in flow characteristics during its regulation. With an increase in the value of TPRFR for basins, an increase in the relative reduction of water runoff in high water is observed, which indicates a significant contribution of artificial reservoirs to the reduction of runoff in the spring period.