Abstract
An integrated hydrochemical and geospatial assessment was performed to access the water quality of wastewater accumulation basins and adjacent aquatic systems in the Zhambyl region (southern Kazakhstan) under conditions of increasing anthropogenic impact. Monitoring was carried out at eight sampling points (P1-P8) during three seasonal campaigns (September 2025, November 2025, and January 2026). The measured parameters included pH, oxidation-reduction potential (ORP), dissolved oxygen (DO), salinity, total dissolved solids (TDS), electrical conductivity (EC), and chemical oxygen demand (COD). The results demonstrate pronounced spatial variability in hydrochemical conditions. The highest levels of contamination were recorded at the wastewater treatment facility (P1) and in the upstream accumulation basins (P2-P3), where elevated COD values (up to 126.4 mg/L) and critically low DO concentrations (as low as 0.63 mg/L) were observed. In contrast, the peripheral sites (P7-P8) exhibited comparatively stable and less impacted conditions. Seasonal analysis revealed a clear increase in organic pollution and oxygen depletion during the winter period, likely associated with reduced dilution capacity and temperature-dependent biochemical processes. The findings indicate that insufficiently treated wastewater represents the primary driver of hydrochemical deterioration in the studied area. These results underscore the necessity for improved wastewater treatment strategies and the implementation of continuous monitoring frameworks. The application of GIS-based modeling further demonstrated its effectiveness as a tool for spatial analysis, environmental assessment, and informed decision-making in sustainable water resource management.