Water Flow Changes In The Don River (European Russia) During 1891–2019

The Don River Long near Razdorskaya Village had long phases (lasting 33–86 years) of increased/decreased naturalized annual and seasonal water flow, and their properties for 1891–2019 were identified. Long-term changes in the annual and snow-melt flood flow occurred in the opposite phase relative to changes in the winter and summer-autumn flow. Annual hydrographs in the phase of decreased flow were characterized by an increase in water discharge during the low-water seasons of the year, but a noticeable decrease in daily flood water discharge and maximum water discharge. The share of high-water years (years with a flow exceedance probability equal to or less than 25%) in the phase of increased flow is significantly higher than the share of low-water years (years with a flow exceedance probability equal to or more than 75%). And on the contrary. At the same time the cumulative share of low- and high-water years remains relatively stable.  The total changes in the annual and seasonal flow, caused by both anthropogenic and climatic factors, throughout the entire period of modern global warming (since 1989) consisted in a decrease of the annual and snow-melt flood flow and an increase of flow values during low-water seasons.