Ecological Indicators (Aug 2024)
DIRECT index – A coupled indicator of groundwater vulnerability to pollution and groundwater-dependent ecosystems risk
Abstract
Methods for assessing the groundwater-dependent ecosystems (GDEs) risk remain underexplored, particularly concerning the threat of groundwater pollution. This article presents the application of the DIRECT index – a multicriteria indicator – designed for the coupled assessment of groundwater vulnerability to pollution (GV) and the risk affecting GDEs. This ecological indicator modifies the DRASTIC index to enable the assessment of GDEs pollution risk and provide a more holistic approach. The assessment of GV and GDEs risk was conducted in areas with varying hydrogeological and geomorphological conditions within a temperate climate zone in Poland (Central Europe). In the reference scenario, GV was categorized as high and very high, constituting 53% and 41% in the Świder and Wisłok study areas, respectively. Spatial variability in GV was noted, with the highest values observed in river valleys where the majority of GDEs are located. The proportion of areas with very high and high-risk GDEs accounted for 73% and 44% of the total GDEs area in the study regions, respectively. Additionally, 59% and 45% of all springs in these areas were situated in zones deemed to have extremely high and high GDEs risk, respectively. A further objective of this study was to project how GV and the associated risk to GDEs might evolve up to the years 2050 and 2100. Four climate change scenarios were examined under the RCP4.5 and RCP8.5 emission pathways. The projections indicated that climate change effects, primarily increases in groundwater recharge, could elevate the pollution risk to GDEs by 2050, with a potential slight reduction by 2100. The application of the DIRECT index facilitated a scenario-based assessment of GV coupled with an evaluation of pollution risk to GDEs. This approach should prove beneficial for managing this risk in the context of climate change and aid in preserving the overall ecological status of GDEs.
