Extreme Low Flows in Rivers of the East European Plain in the 19th–21st Centuries

Abstract

This study is focused on extreme low flows in rivers (when water flow is less than or equal to 75 and 90% exceedance probability) in the East European Plain (Volga, Don, Dnieper, Western Dvina, and Northern Dvina) in the 19th–21st centuries. It is shown that the proportion of years in which an extreme low flow is observed in one or more seasons of the year or in the year as a whole during the entire observation period varies from 46 to 57%. In 30 years, a low flow formed only in one basin under consideration, and in 50 years, it was observed in several (from 2 to 5) basins simultaneously. In seven years, an extreme low flow was observed in different hydrological seasons and during the entire years simultaneously in all the rivers and, in nine cases, in four basins. Modern global warming leads to a significant decrease in the number of low-flow years in the winter and summer-autumn low-water seasons and the year as a whole for all the rivers under consideration. In years when severe draughts were recorded in the territories of all river basins under consideration, low flows were recorded only in 1921 and 1972.