Where could surface water be used for Managed Aquifer Recharge (MAR) in the Besòs catchment, considering quantity and quality?

Abstract. Enhancing aquifer recharge could support climate adaptation in the Besòs basin and in the rest of Catalonia (Spain). This study examines how water quality in aquifers and streams varies along the catchment, and changes in surface water quality during wet and dry periods. Data from 2013 to 2023 from 20 river stations and 26 wells were used to map salinity (EC, Na+, Cl−, SO42-) and nutrient parameters (PO43-, NH4+, NO3-, TOC). Results indicate declining water quality downstream, necessitating salinity control during dry periods and ongoing nutrient management even in wet periods to preserve groundwater quality. These findings will inform the development of numerical models to test MAR methods and recharge strategies in the basin.