Monitoring freshwater salinization in analog transport models by time-lapse electrical resistivity tomography

► We investigate freshwater salinization in a laboratory sandbox model. ► Electrical resistivity tomography (ERT) is applied to monitor saltwater intrusion into a freshwater-saturated porous medium. ► Borehole electrodes are inevitable for an early detection of freshwater salinization. ► Crossed bipoles outperform regular bipole measurements in a surface-borehole setup.