Abstract
The change in the flow of plain rivers in Kazakhstan in recent decades is done due to the influence of both climatic factors and anthropogenic impacts. Revealing their role is extremely important for understanding the genesis of hydrological changes that have already occurred and possible in the future, as well as for taking measures to reduce their undesirable consequences. The complexity of solving this problem lies in the fact that climatic and anthropogenic changes in river runoff are closely interrelated and often interact on the runoff not directly, but indirectly. The intensity of anthropogenic impact, the variability of climate characteristics determine changes in the hydrological regime of water bodies. Climatic variability leads to an increase in the likelihood of adverse hydrometeorological phenomena, and human economic activity in the watershed and in the riverbed leads to a quantitative and qualitative change in the main characteristics of the hydrological regime, degradation of river ecosystems. The changes in the annual runoff of plain rivers are estimated based on the method based on the restoration of the natural runoff of the last decades, during which significant anthropogenic changes took place. It is shown that climatic and anthropogenic factors act on the runoff both unidirectionally, increasing or decreasing it, and in opposite directions. At the same time, the influence of anthropogenic factors, mainly reservoirs and water consumption, is commensurate with the influence of climatic factors, and in many cases exceeds it.