Evaluating climate and water regime transformation in the European part of Russia using observation and reanalysis data for the 1945–2015 period

Abstract

ABSTRACT The river runoff regime significantly changed worldwide in the end of twentieth – the beginning of twenty-first century. In the European part of Russia the current changes are manifested in different ways in various regions. The main trend that is observed for most river basins is the ‘levelling’ of annual hydrographs. The interception of melt water during occasional thaw floods has resulted in a decrease in river runoff during the spring months. Simultaneously an increase in the low water period during winter and summer occurred. Reducing in the depth of soil freezing, caused by warm winters, lead to higher groundwater replenishment. At the same time, the loss of melt water to surface retention as well as evaporation has increased. Almost in all seasons of the year the number of occasional flood peaks increases. Occasional floods are superimposed both on the rise and the decline of seasonal snowmelt flood wave, making it difficult to separate it as an independent phase of the water regime. Changes in seasonal characteristics of river runoff are the most evident in the Don and Oka basins. A significant transformation of the water regime is observed in the north-west of European Russia as well. To a lesser extent, the described patterns are typical for the northern rivers and the eastern part of the European Russia – the Kama and the Ural Basin.