VARIABILITY OF THE WATER REGIME OF THE LOWER DON.

Climate change and its impact on the environment is an urgent problem of the present time, causing hydrological changes and ecosystem change. As a result, formed ecosystem representing less valuable in economic terms, low productivity. Therefore, study of climate change is an important and urgent task. Global climate changes in the South part of Russia is reflected in the warming of the winter period and an increase in the amount of precipitation during the cold season. This paper analyzes the changes in meteorological conditions in Rostov region and its influence on water regime of the Lower Don. Rostov region is located in the Western subdomain of the Atlantic-continental steppe region, temperate zone. The climate of the region is moderate continental, formed under the influence of air mass transfer from the Atlantic, meridional Northern and southern transfers and transformation of air masses. Flat terrain favors the flow of air masses of different origin. The river flow is formed in the steppe zone. Spring flood depends on soil moisture and moisture reserve in the catchment area. The total water content of the river depends on the amount of winter precipitation and air temperature. The main flow (60 - 65%) formed by meltwater in the spring, 25-30% - through underground supply and 3-5% at the expense of atmospheric precipitation. River is characterized by high and long spring flood. In natural conditions, it accounts for about 70% of annual runoff. Tsimlyanskoe reservoir smoothed seasonal distribution of runoff. Until 1952, spring floods accounted for 78% of runoff and 22% for the rest of the year. After the launch of the reservoir, the situation changed. Only 47% the flow of the river falls in the spring. The rivers of the Don basin are now experiencing a decrease in spring runoff. At the same time, there is an increase in summer, autumn and winter runoff in comparison with the period of climatic norm. Analysis of the annual distribution of runoff led to the allocation of two periods: before the construction of the Tsimlyansk reservoir and after the start of operation. Since 2007, there has been a constant decrease in the water content of the river, which lasted until 2016, the low-water regime. [ABSTRACT FROM AUTHOR]