Study of groundwater vulnerability in three unconfined aquifers in Slovenia

Groundwater is the main source of drinking water in Slovenia, but nitrate pollution originating from agriculture and urban areas is threatening its quality in several areas of the country. The aim of this study is to assess the vulnerability of three different unconfined aquifers in Slovenia (Ljubljansko polje, Dravsko-ptujsko polje and Krško-brežiško polje). All three study areas are located on alluvial plains with shallow groundwater levels and similar soil types, but different ratios of urban and agricultural land use. Soil types and land use were analyzed in each area as they contribute strongly to leaching of nitrate. Along with this we performed the analysis of stable isotopes of O, H and N to determine the origin of groundwater recharge and trace the possible sources of nitrate pollution. Results will give us an overview of nitrate pollution pathways through better understanding of nitrate sources, vulnerable areas, and groundwater recharge characteristics.