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Groundwater is a key resource for drinking water supply, as well as for agricultural and industrial use. However, shallow aquifers are increasingly polluted due to human activities, particularly agriculture. Nutrients, pesticides, and emerging organic contaminants (EOCs), which are largely unregulated yet potentially hazardous, pose a serious threat to ecosystems and human health. Nitrate pollution remains a pressing issue and often exceeds established threshold values. The age of groundwater, determined through dating methods, helps assess aquifer vulnerability and pollution trends. Integrated models such as SWAT and Modflow support understanding of flow dynamics and contaminant transport. EU directives aim to protect water resources, although their implementation remains incomplete. Climate change introduces additional uncertainty, making a comprehensive approach – combining monitoring, modelling, and adaptive management – essential. Collaborative research on pollution, land use, and hydrogeology is crucial for the effective protection of groundwater now and in the future.

Groundwater pollution is becoming an increasingly significant environmental problem not only in Europe but worldwide, particularly due to agricultural activities and inadequate wastewater management. Elevated nitrate concentrations – often exceeding the limit of 50 mg/L – pose risks to ecosystems and human health. Emerging organic contaminants (EOCs), which are mostly unregulated, further complicate the situation. Their mobility and unknown long-term effects make monitoring and control more difficult. Conventional sampling methods often fail to capture actual environmental conditions. Passive sampling techniques enable more comprehensive and cost-effective tracking of contaminants. Groundwater age, isotopic indicators, and recharge data help identify pollution sources and assess aquifer vulnerability. Climate change, with its extreme weather events, further affects groundwater flow and contaminant dispersion. A holistic, transboundary approach that integrates climate, agricultural practices, and hydrogeology is essential for sustainable groundwater management and for reducing environmental pressures on water resources.

The main objective of the project is to improve understanding of pollutant transport from agricultural land into groundwater. To this end, data on nitrate and emerging organic contaminants (EOCs), soil permeability measurements, and groundwater age distribution will be used. The impact of different climate scenarios will be assessed using groundwater flow and solute transport models.

Specific objectives:
• Cross-border cooperation between Slovenia and Croatia through the establishment of a joint monitoring network and database.
• Assessment of pollution in the transboundary aquifer (the Krško Field in Slovenia and the Zagreb Aquifer in Croatia) using chemical, isotopic, and quantitative analyses, and evaluation of agricultural practices.
• Development of methods to assess anthropogenic impacts, including passive monitoring stations, mini-lysimeters, a conceptual aquifer model, and climate change scenarios.
• Identification of measures to improve water quality in agriculture, industry, and urban spatial planning.
• Providing a scientific basis for coordinated transboundary aquifer management.

Project partners:

• Biotechnical Faculty, University of Ljubljana (Slovenia) 
• Croatian Geological Survey (HGI – CGS) (Croatia) 
• Ruđer Bošković Institute (Croatia)

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