Influence of river flow regulation in the Angara-Yenisei region on the hydrochemical regime of the cascade of hydroelectric power plant reservoirs and their downstream sections

Abstract

The paper gives an analysis of the influence of river regulation on the chemical composition of surface waters in cascades of HPP reservoirs and downstream sections on the example of the largest rivers of Eastern Siberia. After regulation changes in the temperature regime of watercourses occur, which leads to a change in the timing of the onset of the main ice formations and the emergence of non-freezing sections of rivers. There is a local oxygen deficiency in the summer in the bays and the near-bottom horizon. According to the ionic composition surface waters belong to the hydrocarbonate class of the calcium group. A change in the morphometric parameters of water bodies causes a chain of subsequent hydrochemical reactions. In surface waters, there is a violation of fishery standards for the content of Al, Fe, Zn, Mn, Al, Cu, phenols and oil products. The integral assessment of water quality by the value of the specific value of the combinatorial index of water pollution shows a high fluctuation along the rivers. The risk of negative impact on the watercourse increases with increasing concentrations of pollutants relative to natural conditions.