ANALYSIS OF THE HYDROCHEMICAL REGIME OF THE DNIPRO RESERVOIRS

Abstract

A complex of issues was considered, namely: hydro-chemical pollution of catchment landscapes, bottom sediments of river basins and groundwater, slowing down of underground flow due to the regulation of the river network, regional development of flooding, presence of landscapes contaminated with radionuclides, and the growth of global climate change. All above as well as the ongoing war in the territory of Ukraine affect the conditions of the formation of the hydro-chemical regime and contribute to the changes in the quantitative and qualitative water indicators in the Dnipro River basin and the Dnipro reservoirs, as the main sources of water supply for Ukraine. The research determined the changes in the hydro-chemical regime of the surface water of the Dnipro reservoirs during 2016-2022 to specify the impact of climate change and anthropogenic factors on the drinking water supply. The dynamics of changes were analyzed for individual qualitative indicators of the surface water of the Dnipro reservoirs in the cold (January) and warm (July) months of the year. It was proven that the accumulation of flood water affects the mineralization of the Dnipro reservoirs along their longitudinal axis, and the mineralization rate and the content of the main ions are significantly affected by the water content of the year. It was established that, in the Dnipro reservoirs, the lower limit of mineralization relative to natural conditions increased by 55%, and the upper limit decreased by 30%. It was determined that despite the seasonal changes in the concentration of ions in the water of the Dnipro reservoirs, their ratio for each reservoir remains practically constant and only sometimes changes in the case of a shift in the carbonate balance and in the confluence of more mineralized waters, which increase the content of Mg2, Na+, K+, and SO42-. The predominant water cation is Ca2+, the anion is HСО3-, and the absolute and relative content of other ions is much smaller. The metamorphism of the water of the Dnipro reservoirs changed the ratio of ion concentrations, namely the relative amount of SO42-, Cl-, Na+, and K+ ions increased. The obtained results of changes in the quality indicators of surface water in the Dnipro reservoirs have proved the dependence of the formation of the hydro-chemical regime of the reservoirs on the impact of climate change, economic activity, and the consequences of military actions.