1D Inversion of Resistivity and Water Content of Magnetic Resonance Sounding

Magnetic Resonance Sounding (MRS, or Surface Nuclear Magnetic Resonance, SNMR) is used for groundwater exploration and aquifer characterization. It provides valuable information about geometry of the aquifer, water content and hydraulic conductivity. <br>In MRS, since the excitation magnetic field depends on the resistivity of the subsurface, it has to be taken into account in the inversion. Currently, resistivity is provided by a priori information from supplementary geoelectrical measurements or by assumptions. We developed an inversion scheme for MRS to invert also for the resistivity directly from the MRS data. <br>Results for synthetic data show that the water content, layer boundaries and resistivity can be derived using only the amplitude of the MRS data. However, using amplitude and phase of the MRS signal improves the inversion result. The feasibility of the new inversion scheme has been demonstrated by the successful implementation of field data. The resistivities derived from SNMR are comparable with those derived from conventional electromagnetic methods. <br>