Groundwater Safety and Availability Index (GSAI) and its association with salinity indicators

This study assesses the quality of groundwater in the Odra River Basin in Poland, focussing on environmental health risks, temporal variability, and their association with salinity indices. A new indicator, the Groundwater Safety and Availability Index (GSAI), was developed to evaluate groundwater resources by integrating health risk and resource quantity factors, providing a novel tool for ranking water resources and informing environmental and administrative decision-making. Groundwater samples were collected between 2005 and 2021 and analysed in accordance with national standards. The results demonstrate an improvement in groundwater quality over time, indicated by a reduction in Health Index (HI) values, particularly in Lower Silesia, Lubusz, and Silesia. Significant correlations were found between HI and NO₃^- (τ-Kendall = 0.40) and arsenic (τ-Kendall = 0.55). GSAI values varied across regions, with West Pomerania showing the highest groundwater safety and availability, while Silesia had the lowest. Elevated concentrations of contaminants such as arsenic and nitrates were found to significantly impact water safety, particularly during hydrogeological droughts. These findings support the need for region-specific management strategies to ensure sustainable groundwater use and mitigate health risks, with the GSAI serving as a valuable tool for policymakers and environmental planners.