ИСТИНА

Contemporary global warming is a fundamental driver for the observed long-term changes in water cycle during past decades. Under climate change, frequency of snowfalls and rainfalls can change considerably. Changing patterns of winter precipitation and temperature have resulted in changes to the ratio of snowfalls/rainfalls to total precipitation. This shift primarily occurs during spring and autumn as precipitation shifts from snowfall to rainfall due to winter warming and shortening the snow cover duration. This also results in change of seasonal structure of river runoff including maximum melt water discharge. The liquid/solid precipitation ratio has increased in the regions with significant frequency of warm events in winter, particularly in the south and west of the East European Plain.Estimates of comparative share of liquid and solid precipitation in Volga runoff variability obtained using multiple stepwise regression show the leading role of solid precipitation for the whole period 1951-2006 and increase of impact of liquid precipitation since 1976. While change of liquid/solid precipitation ratio is in accordance with low-frequency spring runoff tendencies, revealed negative correlation between liquid/solid precipitation and spring runoff demonstrates the opposite course of their interannual anomalies and thus suggests decrease of extreme flood risks under contemporary climate change.