SPATIAL VARIATION PATTERNS OF GROUNDWATER CHEMICAL COMPOSITION IN THE UPPER HYDRODYNAMIC ZONE OF THE FERGANA REGION

This article describes the distribution of water content in wells in the Fergana region according to geochemical features. The most important issue of regional hydrogeochemistry is hydrogeochemical zoning, which manifests itself in a natural change in the composition and mineralization of groundwater in area and depth. During the research, the hydrogeological conditions of the territory, the lithological and stratigraphic features of aquifers, and their feeding and depletion conditions were analyzed. Based on the results of hydrochemical analyses, the spatial differentiation of groundwater by mineralization level, water types (hydrocarbonate, sulfate, chloride, and mixed), and prevailing cations and anions was studied. Zones with varying intensities of leaching processes, ion exchange, water mixing, and evaporation processes have been identified. It has been established that spatial changes in the chemical composition of groundwater are caused by a combination of natural factors (geological structure, lithology of rocks, hydrodynamic conditions, climate) and anthropogenic impact (irrigation, drainage, economic activity). Special attention is paid to the role of irrigation water use in the transformation of the hydrochemical regime of the upper hydrodynamic zone. The obtained results have practical significance for quality assessment.