DRINKING WATER QUALITY IN THE DON DELTA IN THE LACK OF WATER CONDITIONS

Lack of water and regulation of the Don river runoff led to an irreversible transformation of natural hydrological and hydrochemical processes. At the end of 2022, despite of the shortage of river water, the region began laying a water pipeline to the Donbass, with a capacity of up to 300,000 cubic meters of water per day. Are there enough reserves of water resources for ever-increasing economic needs, throughout the year? The work is based on a targeted study of the chemical composition of water under different regimes and sea levels on the Taganrog coast of the Don Bay and Delta. The experiment covers the period from December 2, 2022 to January 30, 2023, and separate measurements, for comparison, on February 21; 30.03; 17.04.2023. Summary, three types of ionic composition were distinguished, which characterizes the Svinoe arm of the Don delta. Marine - with dominance (more than 80%) of summary amount of sodium and potassium ions, chlorides and salinity up to 7–9 g/L. The Don waters correspond to low mineralization (less than 2 g/l), an increased proportion of Na⁺ + K⁺ (50–60%), a close amount of SO\(_{4}^{{2 - }}\) and HCO\(_{3}^{ - }\) (30–40% each). Since 2018, the presence of ground waters has been regularly recorded when the level decreases. There are brackish waters with a salt content of more than 5 g/L. They typically have a high content of sodium and potassium (more than 60%) and sulfate ions (60–80%). Monitoring shows, that the shortage of fresh drinking water will increase, and as its withdrawal increases, it will accelerate in time. It will be replaced (up to 5–7‰) with mineralized ground and Black Sea water. In what proportions will be pumped (redistributed by seasons) weakly brackish (2–4 g/L) and brackish (4–8 g/L) water into water pipelines remains to be explored.