- 1Department of Geology, University of Tartu, Tartu, Estonia
- 2Department of Hydrogeology and Environmental Geology, Geological Survey of Estonia, Rakvere, Estonia
- 3Department of Geology, University of Latvia, Riga, Latvia
Groundwater is a critical resource that supports ecosystems, agriculture, and drinking water supply, yet its sustainable management faces challenges, particularly in the transboundary regions. Collaborative approaches are needed to protect this shared resource, as pollution or overexploitation in one country can have significant consequences across borders. The Estonian-Latvian transboundary area is a good example of these challenges, with its reliance on both unconfined Quaternary aquifers, essential for ecosystems and rural communities, and confined first bedrock aquifers, critical for centralized water systems.
This study develops a transboundary aquifer vulnerability assessment framework, integrating harmonized methodologies to evaluate natural vulnerability and pollution risk. The analysis uses the DRASTIC and modified DRASTIC index-based methods, combined with the DRASTIC-L approach, which incorporates land use data for a comprehensive evaluation of both natural and anthropogenic pressures. To improve the reliability of the assessment, pollutant travel time calculations were used to validate the findings.
The results show high variability in aquifer vulnerability across the study area. The unconfined Quaternary aquifer is most vulnerable in regions with sandy sediments, shallow groundwater tables, and high recharge rates. The confined bedrock aquifers are covered with protective sediment layers, but their vulnerability varies depending on sediment thickness and hydraulic conductivity. Notably, discrepancies between Estonian and Latvian geological data were uncovered, as large polygons of well-protected areas often terminate abruptly at the border, highlighting inconsistencies in geological data between Estonia and Latvia.
This framework emphasizes the importance of integrating natural vulnerability maps, pollution risk assessments, and harmonized methodologies developed for regional geological conditions. The study offers a scalable and adaptable solution for transboundary aquifer management by addressing data inconsistencies and fostering international cooperation.
Integrating these insights into transboundary water management strategies can greatly improve decision-making by providing a more comprehensive understanding of groundwater vulnerability and pollution risks. Additionally, it helps to make groundwater systems more resilient to future challenges like climate change, land use changes, and increasing water demand. Ultimately, this approach supports the sustainable use and protection of shared groundwater resources, ensuring their availability and quality for current and future generations.
How to cite: Männik, M., Bikše, J., and Karro, E.: Advancing harmonized groundwater vulnerability assessments for sustainable management in the Estonian-Latvian transboundary aquifers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10445, https://doi.org/10.5194/egusphere-egu25-10445, 2025.