Climatic factors of the Volga runoff variability in the second half of 20th – early 21st centuries

Abstract

The relation of the Volga runoff to the change of climatic factors, significant for the river runoff, is considered since the middle of the last century. The quantitative estimates of the impact of precipitation anomalies (taking into account the solid and liquid phase) on the variability of the annual runoff of the Volga show that the leading role of solid precipitation is detected in the period preceding the current warming (from the early 1950s to the mid-1970s), and also from the mid-1990s, with the onset of warming hiatus. From the mid-1970s to the 1990s, during the period of winter temperature growth, a significant increase in the role of liquid precipitation and their dominance in the variability of the Volga's runoff is observed. The differences between these periods are also noticeable in the percentage of liquid precipitation in the annual amount, which in turn has an ambiguous effect on the spring runoff of the Volga. The long-term trends of spring runoff and the share of liquid precipitation (in annual amount) before and after the mid-1970s coincide in sign. In the same time, there is a negative correlation between the anomalies of these parameters in interannual scale. The last indicates a decrease in the volume of runoff in the years of increasing the proportion of liquid precipitation.