Risk for water shortage in Ystad Municipality - An evaluation of aquifer vulnerability to human impact

Abstract

The risk for drinking water scarcity does not only concern developing countries and arid places. In its 2023 report, the Intergovernmental Panel on Climate Change has identified water scarcity as one of Europe’s key risks out of five in the foreseeable future. Sweden experiences water shortages more and more frequently during summer, and the need to protect groundwater resources is imperative. In this study, an aquifer in Southern Sweden was evaluated for its vulnerability to climate change and pollution. A correlation analysis between meteorological, hydrological and groundwater data for the past 30 years was performed to analyse their interactions and evaluate how dry conditions and groundwater abstraction impact the aquifer. A qualitative analysis of pollution sources in the catchment was conducted to estimate the risk for groundwater contamination. A groundwater steady state model was built for a waterworks in a part of the aquifer using MODFLOW 6 and its extension MODPATH to identify the probabilistic capture area of the system. PEST++ was used to calibrate the model and quantify its uncertainty through an Iterative Ensemble Smoother.
The results show that, via a chain of interactions, an increase in consecutive dry days eventually leads to a lowering of the water table. Groundwater abstraction and the part of evapotranspiration in the water cycle explain the weakness of certain relationships. Pollution sources within the catchment are multiple and the most immediate threats come from agriculture, urban areas and atmospheric deposition. A lack of systematic monitoring of specific contaminants creates knowledge gaps about leaching from the different sources to the aquifer. The model results show that infiltrated water molecules (particles in the model) hit the model boundaries, indicating that the probabilistic capture extends beyond the model extent and beyond the Water Protection Area. More observation wells would be needed to fully model the capture area for this waterworks. Recommendations to the authorities are to extend the Water Protection Area of the waterworks, implement ecological measures to maintain soil moisture, limit eutrophication and reduce the use of pesticides, as well as create a unified database between municipalities to strengthen water resources management.

Popular Abstract

Over the last decade, summer droughts have led several regions in Sweden to experience a decrease in groundwater levels. As a consequence, households and agriculture are impacted by temporary water-use restrictions called water shortages. The resulting reduced volume of water in the soil may not be usable for drinking water if subjected to pollution, because the concentration of pollutants would be higher. To protect our groundwater from pollution, we need to preserve the area where the water recharging the aquifer infiltrates. I investigated the risk of water scarcity in Ystad municipality, southern Scania, by assessing the vulnerability of the Fyledalen aquifer to climate change and pollution. My research focused on Nedraby's waterworks, located within a portion of the aquifer.
I analysed the correlation between rainfall, river levels and groundwater levels for the time period 1994-2023 to evaluate the effect of dry conditions and pumping on the local water cycle. Within the surface catchment area draining waters into Fyledalen, I identified pollution sources using public information and observations. Thanks to a 3D representation of the aquifer called a groundwater model, it was possible to retrace the path taken by water from the ground surface to the pumping wells in Nedraby. Because the use of pesticides and certain hazardous activities are restricted in Water Protection Areas (WPA), the purpose of identifying the well capture zone in Nedraby was to evaluate whether its WPA is sufficiently large to prevent harmful substances from reaching groundwater.
The results show that dry conditions negatively impact Fyledalen’s groundwater through a chain of interactions within the water cycle, and that pumping potentially leads to a decrease in river levels. Pollution sources in the area are multiple and come from agriculture, urban areas, atmospheric pollution and old landfills. As seen on the map, the groundwater model encompasses Nedraby’s WPA. Because the water particles “hit” the model boundaries, it means that the well capture zone extends beyond the model boundaries and therefore beyond the WPA. According to the model, Nedraby’s WPA should be extended as a safety measure. Despite the model imperfections, this study shows the power of groundwater modelling in decision-making to improve drinking water quality.

• author: Durdek, Madeleine
• supervisor: Charlotte Sparrenbom; Nikolas Benavides Höglund
• organization: Department of Geology
• course: GEOR02 20242
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Earth and Environmental Sciences
• keywords: Groundwater, hydrology, climate change, pollution, pesticides, Water Protection Area, MODFLOW, MODPATH, PEST++, Iterative Ensemble Smoother
• publication/series: Dissertations in Geology at Lund University
• report number: 700
• language: English
• id: 9184473
• date added to LUP: 2025-02-13 11:20:55
• date last changed: 2025-02-17 10:00:53