Transformation of the Spring High-water and Flood Runoff in the Upper Volga Basin under the Climate Change Impact

An increase in the average annual air temperature in the European territory of Russia against the background of climate change leads to a decrease in water reserves in the flood-forming snow cover. At the same time, an increase in the number of transitions of air temperature through 0 ° С in the area of positive values in winter leads not only to an additional reduction in snow storage by the beginning, but also ensures an increase in the number and size of thaw floods. Changes in the intra-annual distribution of the range and intensity of precipitation entail an increase in the number and magnitude of rainfall floods. Observed transformations in the types of feeding and water regime of the rivers of the basin. Methods. The study posed the task of studying climate change on the hydrological regime of rivers in the Upper Volga basin. To solve it, methods were used to determine the methods for determining the runoff components based on the dismemberment of the hydrograph using the GrWat software package and mapping the results of the results. As part of this task, more than two thousand hydrographs were analyzed, and their long-term trends were analyzed. Results. The analysis showed that on some rivers of the region the volume of flood runoff is already comparable to the volume of flood runoff, which is not typical for the river-European type of water regime. It was found that for some rivers in the region, the volume of runoff during high water decreased by more than 50%, while the volume of runoff during the period of rainfall floods increased by more than 80%,while in the period of thaw practically by 100%.