INFLUENCE OF 2007–2015 EXTREME LOW FLOW PERIOD IN THE DON RIVER BASIN ON WATER ECOSYSTEMS

The results of analyzing the spatiotemporal variations of 2007–2015 low-flow period parameters are presented. Time-series data on the annual and seasonal runoff were used, as well as hydrobiological data on phytoplankton concentrations and young fish numbers for different species. The role of low-flow period in cyclic runoff oscillations in different parts of the basin, seasonal flow redistribution during the extreme low-flow period, interchange of relatively high-water years with relatively low-water years within the period and the increase of water flow probability from the river source to its mouth is discussed. A considerable decrease in phytoplankton concentration in the middle reaches of the Don River during the low-water years was revealed. The decreasing reproduction of the majority of fish species is characteristic of the Tsimlyansk reservoir caused by the shrinkage of spawning areas during the low-water years.

river runoff, water scarcity, the Don River, the Tsimlyansk reservoir, probability, concentration of phytoplankton, fish fauna, reproducing ability, yearlings.

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