FORECASTING THE RISKS OF NITRATE AND MICROBIOLOGICAL POLLUTION OF SOURCES OF DISTRICT WATER SUPPLY

Abstract

The study is aimed at providing a scientific substantiation of methodological approaches to the predictive assessment of risks of nitrate and microbiological contamination of decentralized water supply sources, taking into account the conditions of water quality formation. For this purpose, a comprehensive investigation of the problem of nitrate and microbiological contamination of individual and public water intake facilities was conducted. This issue has remained one of the most pressing challenges for rural areas in countries with highly developed agricultural sectors for many years. The persistent and multifactorial nature of these types of contamination is determined by the combined influence of natural hydrogeological conditions, the intensity of land use, the technical condition of engineering infrastructure, and the effectiveness of environmental control. In this context, the development of a reliable tool enabling individualized assessment and prediction of nitrate and microbiological contamination risks for each specific water supply source within rural settlements becomes particularly relevant. To address this objective, a modified Leopold matrix is proposed as a tool for risk prediction, taking into account the conditions of groundwater quality formation. Decentralized water supply systems are typically associated with risks arising from non-compliance with sanitary and hygienic requirements when selecting locations and arranging both public and private wells. Common violations include the placement of water intakes in close proximity to potential sources of contamination—such as cesspits, outdoor latrines, sewer networks, livestock facilities, abandoned shaft wells—as well as the absence of properly established sanitary protection zones around water intake structures. The results of the predictive assessment make it possible to identify the key factors determining the formation and spread of nitrate and microbiological contamination for each studied source. Based on the adapted Leopold matrix, a unified template has been developed to determine the category of a facility depending on the established level of risk. The assigned category defines the monitoring regime and the implementation of a set of measures aimed at minimizing the risks of nitrate and microbial contamination of groundwater aquifers.