Sediments of the Rhone river are characterized by strong heterogeneity between clay, sand and gravel units. To map these units, we employed an electromagnetic instrument (DualEM421). This instrument das the advantage that no contact to the ground is required and it can be carried on foot.
With the interpreted data it was possible to map different geologic units to a depth of up to 4.5m.
3D inversions of EM data allow for accurate mapping of terrain conductivity on the top 6 meters below ground level