The lithological and stratigraphical heterogeneity of coastal aquifers has a great influence on saltwater intrusion (SI). This makes it difficult to predict SI pathways and their persistence in time. In this context, a combination of both laboratory and field geophysical methods including electrical resistivity tomography (ERT), (spectral) induced polarization (SIP, IP), and electromagnetics (EM39) is used to discriminate the presence of saltwater-bearing and clayey sediment layers in the Luy River catchment, Vietnam.