Hydrogeological characterisation of an integrated Managed Aquifer Recharge system in southern Poland using Electrical Resistivity Tomography

Abstract

Groundwater represents the primary source of drinking water in many European countries, making the sustainable use and protection of this resource a strategic priority. However, climate change, intensive abstraction, and contamination of aquifers are increasingly negatively affecting them. Managed Aquifer Recharge (MAR) can enhance groundwater quantity and quality, but its effective implementation requires a detailed understanding of the site's hydrogeological characterisation. This study assessed the geological framework and hydrogeological conditions of the Świerczków well field in Tarnów, Poland, using Electrical Resistivity Tomography (ERT). Eight ERT profiles (54–315 m in length) were acquired, allowing the determination of subsurface structures at depths of 10–24 m. The data, jointly interpreted with borehole logs and groundwater monitoring results, enabled the delineation of three principal zones: an unsaturated zone (40–200 Ωm and 200–650 Ωm), a high-resistivity aquifer (up to 1500 Ωm), and a Miocene aquitard (4–200 Ωm). Spatial electrical resistivity variations reflect differences in lithology and groundwater electrical conductivity, supporting identification of zones influenced by MAR recharge and areas receiving inflow of more mineralised native groundwater from the industrial zone. ERT results contributed to optimising the placement of new observation wells and improving the conceptual and groundwater flow model of the site. This research indicates that ERT is a reliable method supporting MAR system management.