One-dimensional hydrogeophysical forward model in surface nuclear magnetic resonance (SNMR) computations

Surface nuclear magnetic resonance (SNMR) technique is a novel method for the detection of groundwater and characterization of aquifers. A three-layered Earth model with a conductive-sandwiched bed (aquifer) within resistive layers has been used for estimating the SNMR signal. The magnetic field expressions have been developed for a three-layered medium due to an oscillating magnetic dipole kept above air-Earth interface. It involved independent theoretical formulation of the forward problem. For a given depth-wise distribution of water content confined to a three-layered Earth medium, the NMR signal response has been sought. The forward model is tested in a typical H-type Earth section and the computed NMR signal clearly identified the groundwater presence in the sandwiched layer. The computation of magnetic field expressions for a simple three-layered Earth sets the ground for computation and detection of more complex magnetic fields for multi-layered Earth containing materials of different resistivity. With global need for sustainable requirement of groundwater usage and distribution for various purposes, SNMR technique is slated to provide a means of faster and cheaper hydrological solutions.