Hydrological profile of the river in the drainage territory of the Assa-Talas basin in considering technological processes

Abstract

Based on long-term information and analytical materials, the hydrological posts of the RSE “Kazhydromet” for 1925-2020 created a research base to study the spatial and temporal assessment of long-term fluctuations in the annual river flow in the catchment area of the Assa-Talas basin, using the method of hydrological analogy, linear trends, total, difference and ordinary integral curves, based on mathematical statistics. Studies have shown that the trend of changes in the average annual flow of river water in the catchment area of the Assa-Talas basin for the period under consideration 1925-2020 is negative, where changes in the hydrological regime of the river occur symmetrically and sequentially proportionally in the spatio-temporal scale, there are two quasi-homogeneous periods characterizing the transition from natural activities to anthropogenic. An assessment of changes in the water content of rivers in the catchment area of the Assa-Talas basin and the synchronism or asynchrony of its long-term fluctuations, performed on the basis of normalizing the difference integral curves of the modulus coefficients of the average annual water discharge using the method of difference-integral curves, showed that in all hydrological stations from 1925 to 1975 a high-water cycle is observed, and after that, a low-water cycle begins to the present, but with differences in the timing of the onset of phases and the amplitude of cyclic oscillations. At the same time, the quantitative value of the coefficient of variation increases from the mountainous zone towards the southern desert, where the zones of surface runoff are located and the high average annual water flow in all the rivers under consideration is observed in the range from 1.0 to 25.0% of the supply, and then their quantitative value decreases sharply, which is typical for rivers, where atmospheric precipitation, melting snow cover and groundwater are sources of food.