Using geochemical data and modelling to enhance the understanding of groundwater flow in a regional deep aquifer, Aquitaine Basin, south-west of France

Among several potential reaction schemes at each point, only one allowed to reproduce the independent variables (pH and 13C). The developed model was used to select the most probable water pathways at the aquifer scale. In this context, geochemistry clearly demonstrates the role played by subsurface structures on water flow velocities and residence time in their vicinity. In addition, the concentrations of several ions could only be justified by the aquitard-aquifer interactions.