ИСТИНА

Long-term phases (10–58 years) of increased/decreased naturalized annual and seasonal water flow of the Lena River at Kyusyur were identified for 1936–2019; their characteristics were also investigated. The quasi-synchronous character of the sequence of phase changes of increased/decreased values of annual and seasonal runoff was revealed. The greatest difference in runoff in contrasting phases was observed in the winter and summer-autumn seasons, when it was 48 and 30%, respectively, whereas for flood runoff and annual runoff it does not exceed 11-12%. To naturalize the values of the daily water discharge of the Lena River at Kyusyur, a series of measured daily average discharge of the Lena River at Tabaga and Aldan River at Verkhoyansky Perevoz were used. The Kalinin–Milyukov method was used to naturalize a hydrograph of Lena River at Kyusyur. This flow routing method conceptualizes a relation between the inflow and outflow of a river section as a linear function of water stored within the reach. The study was carried out within the framework of the state task of the Institute of Geography of the Russian Academy of Sciences AAAA19-119021990093-8 (FMGE-2019-0007).