Topographic Effects on Radio Magnetotelluric Simulations on Levees: Numerical Modeling for Future Comparison With Fields Results
R. Duval1 C. Fauchard1 R. Antoine1
1ERA23-IFSTTAR, Laboratoire des Ponts et Chaussées de Rouen, CETE-Normandie Centre, France
We study the topography influence of levees on the electric resistivity signal obtained with the Radio-Magnetotelluric method. Field measurements have been modeled with COMSOL, using the AC/DC and RF Modules. A levee situated in Orléans along the Loire river (France) has been considered in order to design a model tacking account of the skin depth and the incident wavelength, keeping a constant field in the whole model. The effect of the incident electromagnetic field direction is assessed with two different incident wave directions: BBC 5 and France-Inter. The simulations highlight the tri-dimensional effects in the apparent resistivity, observed on the crest of the levee, depending on the incident field direction and topography. A buried gas pipe is also characterized.