ИСТИНА

Specific features of water and ice regime of the rivers of European Russia as well as their spatial and temporal variability were studied using the up-to-date hydrometeorological data. Variations in the characteristics of water and ice river regime over the last 125 years are analyzed. For the some rivers potential changes in the dates of the appearance of floating ice and the breakup due to expected changes in the air temperature and the rate of streamflow in rivers are assessed. Special attention is paid to the factors that affect the formation of ice jams and their spatial and temporal variability for the northern rivers. It was found that under low flow conditions, autumn ice and slashed ice drifts became longer, ice jams more frequent, and freeze-up periods shorter. More frequent thawing spells resulted in decreasing ice thickness and snow storage in river basins. Winter break-ups were accompanied by ice jams and floods. High water levels during further freezing-up, as well as large amounts of slashed ice in river channels increased the risk of catastrophic ice jams. It is shown that changes of ice regime are mainly defined by features of water regime. The basic feature of modern changes of rivers water regime on a prevailing part of the country is significant increase of low flow, especially in winter. Within the European territory of Russia for the majority of considered rivers significant positive trends of winter and summer-autumn low flow are marked. There is an increase of natural regulation of rivers drainage. New maps of different characteristics of ice and water regime are presented.