SUMMARY
The features of perennial fluctuations in the river runoff of the Yesil Basin Rivers are considered. The purpose of study is to analyze the spatial and temporal variability of various characteristics of river runoff in the F river basin. In the presented work, the series of annual and maximum water discharges were analyzed, as well as the series for the minimum runoff, based on analysis of runoff long-term fluctuations of the Yesil river basin and the authors' own researches. Hydrological calculations and statistical analysis were carried out using standard Excel and Statistica packages. Based on the processing of surface-based observations (1933-2016 years), as well as the analysis of literature data, conclusions were conducted about the presence of intra-century cycles in the series of the annual river runoff of the Yesil river basin. It was revealed that the Yesil Basin Rivers are characterized by a cyclic runoff with a period of 15-25 years. As a result of the analysis of the long-term variation of the values of the maximum water discharge, noticeable differences in the long-term variation of both the direct values of the maximum discharge and their absolute variability were revealed; it was revealed that the series of the minimum winter and summer-autumn runoff at a significant part of the gauging stations of the Yesil river basin are heterogeneous. The heterogeneity of the runoff series characteristics in the Yesil basin is due to both factors: climatic changes and anthropogenic pressure.