The equations of change in the content of main ions from the mineralization value of the hydroposts of the lower reaches of the Amu Darya River, canals and local small lakes

It is noted that the drying of the Aral Sea has become a large-scale man-made environmen-tal and humanitarian disaster. This disaster led to a regional environmental crisis and serious consequences for ecosystem services, including water use. This requires the development of effective mechanisms for regulating water use and water consumption. The study used data from chemical analysis of the water of the lower reaches of the Amu Darya River, main reservoirs, and small local lakes in the Republic of Karakalpakstan for 2022–2023. and an earlier retrospective period. The research objective consisted in the analysis of the chemical composition of a surface water of the Republic of Karakalpakstan and a conclusion of empirical dependences for assessment of maintenance of the main ions (HCO₃–, Cl–, SO₄–², Са²⁺, Mg²⁺, Na⁺) depending on mineralization size. Analysis of the chemical composition of river water showed that when river water moves from the upper to the lower reaches, the predominant chemical composition changes from hydrocarbonate-sulfate-calcium-sodium to chloride-sulfate-magnesium-calcium-sodium. The obtained equations have a close relationship with the initial data (coefficients of determination R² = 0,80…0,94).