Entropy-weighted model for assessing the environmental safety of surface waters in Ukraine

Abstract

Purpose. To develop and test an adaptive entropy-weighted model that allows eliminating the subjectivity of traditional index-based methods and accounting for the spatiotemporal variability of hydrochemical parameters to improve the efficiency of river basin environmental safety management. Methods. The methodology is based on calculating the Entropy-Weighted Water Quality Index (EWQI), where the weight of each physicochemical parameter is determined using Shannon entropy Results. Observation data from over 540 monitoring points within the main river basins of Ukraine for five seasonal phases of the hydrological cycle were analyzed with cartographic visualization of the calculation results. A clear dependence of water quality on the hydrological regime was established. The best ecological status was recorded in the winter and spring periods (Danube and Vistula basins) due to the natural dilution of pollutants. Critical deterioration of quality is observed during the shallow-water and autumn periods, when pollution indices reach extreme values, especially in the basins of the Southern Bug, and rivers of the Black Sea and Azov Sea regions (classes "very dirty" and "extremely dirty" water). Spatial analysis localized the zones of highest anthropogenic risk, confirming the inefficiency of river self-purification in industrially burdened regions during the lowflow period. Conclusions. The proposed model demonstrated high sensitivity to seasonal changes and anthropogenic load. It provides a scientific basis for transitioning to adaptive water resource management, allowing for the prioritization of water protection measures and the optimization of the monitoring system according to periods of maximum ecological risk.