Modelling-Based Assessment of Managed Aquifer Recharge: Impacts on Groundwater Quantity and Quality in the Upper Friuli Plain (Italy)

In the Friuli Venezia Giulia (FVG) region of northeastern Italy, declining groundwater levels and changing precipitation patterns have raised concerns about the long-term sustainability of groundwater resources. This study evaluates the potential of Managed Aquifer Recharge (MAR) in the upper Friuli Plain, with a focus on the Sammardenchia site. Surface water and groundwater quality in the study area were characterized through the analysis of inorganic and organic compounds, as well as microbiological indicators. A three-dimensional groundwater flow model was developed to simulate the regional and local site-specific hydrogeological conditions. MAR performance was assessed under different recharge scenarios, including an infiltration pond, a recharge well, and a combined pond-well recharge, based on the existing recharge structures at the site. In addition, solute transport simulations were conducted to analyze the behaviour of faecal indicator bacteria (E. coli), detected in the surface water to be used for MAR. The simulation results show that recharge through both the infiltration pond and the well increased the groundwater levels near the MAR site, with the combined recharge scenario producing the highest simulated rise in groundwater levels (~ 2.68 m) and storage. Microbial transport simulations showed substantial attenuation of E. coli during subsurface transport, particularly under the pond-recharge scenario (> 4 log) due to longer residence times. Overall, the modelling results indicate that MAR can effectively contribute to groundwater storage enhancement and attenuation of microbial contamination in the study area. Combined pond−well recharge shows the greatest potential to increase groundwater storage. Longer travel times help reduce simulated E. coli concentrations in groundwater. Different recharge configurations offer distinct benefits, depending on groundwater management objectives.