ASSESSMENT OF GROUNDWATER SAFETY USING A MULTI-MODEL WATER QUALITY INDEX AND HEALTH RISK INDICATORS

This article presents an approach to assessing the quality of groundwater based on a multi-model analysis of the Water Quality Index (WQI) using various weighting methods: expert-based (ISWM), entropy-based (EWM), and health risk-oriented (HRWM). The aim of the study is to identify the most sensitive and objective weighting method for groundwater quality assessment, considering the toxicological characteristics of pollutants and their potential health risks. The methodology involves the normalization of hydrochemical indicators, the calculation of WQI for six wells located in the Izium district (Kharkiv region, Ukraine), and the estimation of risks according to the USEPA guidelines. In the HRWM model, reference doses (RfD) and cancer slope factors (CIC) are used to determine the weight of each pollutant in the overall index. The results indicate that the HRWM approach is the most sensitive to toxic components (such as NO2–, Fe, Mn), able to identify risks even at concentrations below maximum permissible levels. The method effectively highlights priority pollution sources that require immediate environmental attention and monitoring. Limitations of the study include the relatively small number of analyzed wells and the restricted list of parameters with available toxicological data, which may affect the comprehensiveness of assessment in broader applications. The practical value of the approach lies in the ability to adapt the HRWM method for real-world groundwater monitoring, especially in regions with limited analytical or financial resources. It can also be incorporated into decision-making systems for drinking water quality management. The scientific novelty of this research consists in the integrated use of three WQI weighting models within a single study, along with a comparative evaluation of their diagnostic effectiveness in identifying medically and environmentally relevant risks. The approach enhances the incorporation of biomedical criteria into traditional water quality assessment frameworks.