Аңдатпа
The presented scientific study analyzes the long-term regional trends in the intra-annual distribution of river flow in selected catchments in Kazakhstan: the Buktyrma River - Lesnaya Pristan village, Zhabay River - Atbasar city, Ulken-Kobda River - Kobda village, located in the basins of the Buktyrma, Esil and Zhaiyk rivers, respectively, from 1985 to 2022 years. The river basins were selected as regions characterized by different geographical features of flow formation, significantly affected by climate change. To analyze the intra-annual distribution of annual river flow, taking into account the climate changes, a computational method was used, in which the domestic river flow (modern river flow taking into account non-stationarity of climatic changes) was compared with the conditionally natural flow obtained by modeling (using the German SWIM model) and corresponding to the natural regime of the river. The long-term dynamics of flow-forming factors and flow parameters with regard to different water content phases. The assembly method according to V.G. Andreyanov demonstrated the greatest effectiveness in the analysis of the intra-regional distribution of the lowland rivers flow with predominant snow nutrition. Comparison of the modelled (conditionally-natural) and actual (modern) flow revealed key changes associated with climatic factors. The study showed that the intra-regional distribution of the river flow of Buktyrma, Zhabay and Ulken Kobda rivers changes significantly under the influence of climatic factors and atmospheric circulation. The main trends include decrease in spring flow of the Zhabay River, shift in the peak of the high water for a later date for the Buktyrma River and strengthening of the seasonal flow concentration of the Ulken Kobda River. These changes are due to increase in air temperature, change in precipitation and infiltration. The circulation of the atmosphere plays an important role in the flow formation. The western type of circulation helps to increase the water content of the Buktyrma and Ulken Kobda rivers, and the eastern type is associated with high-water years. The analysis showed that atmospheric processes have significant impact on the hydrological characteristics of the studied rivers. For all rivers, the most high-water years are characterized by increased repeatability of type E, with the exception of 1997, 1998, 2015 and 2017years with type W, 2002 with type E + W. In low-water years, by five years for each hydrological station were also used to characterize the formation conditions. For all rivers, most low-water years are characterized by increased recurrence of types W and E, respectively 7 and 8 in number of recurrences.