Changing the nature of long-term fluctuations in the flow of rivers of Southern Yakutia and adjacent areas of the Russian Far East in the context of global warming

The proposed article presents the results of a study of the peculiarities of changing the nature of long-term fluctuations in the water regime of rivers in the conditions of developing global warming. River basins are compactly located within one natural and climatic zone - the region of Southern Yakutia and adjacent areas of the Irkutsk, Amur regions, Khabarovsk and Trans-Baikal Territories of the Russian Federation. This approach made it possible to adequately compare the parameters of changes in the nature of long-term fluctuations in the flow of rivers under similar conditions. The basins of the 6 rivers considered, with a few exceptions, cover the entire territory of South Yakutia. The main trends in changes in the nature of long-term fluctuations in runoff in the modern period (1988-2018) include an increase in water content on most rivers by 16-34%, which, nevertheless, did not lead to a violation of the stationarity of the annual runoff series according to mathematical expectation. The dispersion of annual runoff increased to a greater extent: on 5 rivers out of 6, its growth ranged from 8 to 254%, as a result of which on three rivers (Chara, Timpton, Amga), the annual runoff series lost their stationarity in dispersion. In general, the region has seen an increase in the frequency of occurrence of extreme events - exceeding the historical maximum annual runoff of the base period or the occurrence of an annual runoff less than the historical minimum annual runoff of the base period, and the frequency is gradually increasing within the duration of the modern period. The geographical pattern of changes in the nature of long-term fluctuations in river flow was revealed: to the greatest extent these changes were manifested on the rivers of the western part of Southern Yakutia (Chara, Olekma), to the least - on the rivers of the eastern part (Uchur, Maya).