Groundwater pollution risks assessment in Ukraine-Poland transboundary aquifers

Problem statement. For states that share a common border it is important to have reliable and up-to-date information on the condition of groundwater used for water supply. Transboundary aquifers (TBA) are rather a complicated object for controlling, monitoring research and management due to inherent transboundary flows. Within the framework of the international project EU-WATERRES, the development of a concept for coordinated management and harmonized monitoring of the TBA at the border areas of Ukraine and Poland has been launched. Among many aspects of the project's research scope, it was important to study the risks of groundwater pollution. The study of potential scenarios of anthropogenic impact within the aquifers will make it possible to predict changes in the quantitative and qualitative parameters of transboundary groundwater, which, in turn, will allow qualitative planning of economic activities with minimal risks. The purpose of the study is to qualitatively assess the risks of pollution of transboundary groundwater used for drinking water supply taking into account their vulnerability and the overall anthropogenic pressure. The research methodology is to analysis the cumulative impact of hazards and the degree of vulnerability of transboundary aquifers using the index-rating method as well as to map pollution risks using the overlay method. Research results. The substantial volume of groundwater in the transboundary catchments between Ukraine and Poland (85.3%) is classified as vulnerable and very vulnerable. Within the Polish territory, their share is 99.9%, and within the Ukrainian territory it amounts to 79.5%. In contrast, the study area is marked by a low degree (4.74%) of groundwater pollution hazards. High and very high hazards in Ukraine account for 6.5% of the study area, and in Poland to 0.55%. The calculations and risk mapping showed that low vulnerability minimizes the impact of pollution hazards, and in the absence of anthropogenic pressure the risk may be modest. This is especially important for assessing the quality of groundwater in the main useful aquifers (MUA), which is a valuable water supply resource for both countries. The Roztochchia area is a vivid example of a territory where high anthropogenic pollution hazards are offset by the low vulnerability of the Lower Neogene aquifer, resulting in a significant reduction in risks. Scientific novelty of the research. For the first time, an assessment of groundwater pollution risks for the Polish-Ukrainian transboundary area was carried out. The results of the research can be used in the management and protection of transboundary groundwater between Ukraine and Poland.