Investigation of the long-term variability of the elements of the water balance of the river basin in the modern climate

Abstract

The assessment of changes in the elements of the water balance of the Volga River basin in the formation zone near Volgograd for the entire period of the twentieth century and at the beginning of the first half of the XXI century is considered. The conducted retrospective conjugate analysis of the EWB of the Volga River basin is based on the use of sufficiently long hydro meteorological arrays of initial observation data covering the period 1891/1892‑2020/2021. Two time series of annual and seasonal values of atmospheric precipitation, river runoff, total evaporation of land, changes in basin moisture reserves and changes in surface air temperature of the cold and warm periods and the year as a whole are organized. It was established that until 1935, in the long-term course of the runoff of the Volga River basin, natural factors were of decisive importance, i.e. the nature of the humidification of the territory, the regime of total evaporation from its surface and the change in moisture reserves in the soil-soils. Since 1935, the water content of the river has changed. Human economic activity began to have a significant impact on the Volga, especially the operating modes of the Volga-Kama cascade of waterworks. However, anthropogenic influences do not affect the formation of lateral tributaries, which are controlled by 11 reservoirs of the Volga-Kama cascade. Therefore, for a retrospective conjugate analysis of the EWB of the Volga River basin, two conditionally natural time series of different durations were used