Multilayer resistivity interpretation and error estimation using electrostatic images

This paper presents a method for generating groups of electrostatic images for the estimation of soil parameters in the case of multilayered horizontal soil. The method can be utilized for the interpretation of resistivity sounding measurements of stratified soil. The maximum errors of the calculated resistivity values can also be estimated and are used to validate the soil model. Errors and variations in apparent resistivity values used in the interpretation process can originate from slow convergence in calculations or variations during field measurements, such as local fluctuations in soil resistivity at points of measurements and instruments precision. An estimation of the effect of these variations on the calculated soil model parameters can be used to provide a confidence level in the results. This paper demonstrates the necessity of evaluating the sensitivity of the soil parameters and proposes methods of estimating a confidence level in the soil model. Confidence levels are also used to delimit boundaries during geophysical inversion with respect to the information available in the field measurements. Simulation results are presented for three-layer soil. Index Terms--Electrostatic images, geophysical inversion, grounding, Marquardt method, resistivity measurements, resistivity sounding, soil resistivity, Wenner method.