Correlation between the Dnipro Water Quality Parameters and the Peculiarities of Their Long-Term Changes

Seasonal and long-term changes in the quality parameters of water delivered to the Dnipro Water Supply Station (DWSS) in Kyiv after the Kyiv Reservoir were considered. The range of measured parameters covered the following periods: 1950–1962 until the creation of the Kyiv Reservoir, 1996–2006, and 2012–2022 after its creation. Water quality monitoring was performed by both the standard integral parameters (chromaticity, permanganate and bichromate oxidability, biological oxygen demand, and total organic carbon) and the ratios between them. The statistical analysis and graphic interpretation of data were carried out by Microsoft Excel tools. The correlations between the factors were estimated with the use of Pearson correlation coefficients r. Based on the determined correlations, the quality of water in the water reservoir and at the inlet to the DWSS water treatment facilities in Kiev was balanced between allochthonous and autochthonous sources of organic substances. The changes in water quality characteristics were noticed to be cyclic and correlate in a certain way with solar activity. The consideration for solar activity cycles provides a basis for predicting the Dnipro water quality and should facilitate the technological and logistic support of operation for the water treatment station in coming years.