Improvement of 1D geoelectric sounding by narrowing the equivalence range and identification, quantification and reduction of lateral effects using the tri-potential technique

Abstract

Apparent resistivity data from the Offset-Wenner array (Zemun, Serbia), the square array (Bogatić and Golubac, Serbia) and the Wenner tri-potential technique (Vrdnik, Serbia), were used to detect, measure, and reduce lateral effects in 1D inversion. Forward and inverse modelling with the Wenner α, β and γ arrays determined that the Wenner β array provided the most accurate estimate of the first-and second-layer resistivity, while the Wenner γ array provided the most accurate estimate of the high resistivity substratum. The survey on the Zemun loess plateau revealed that if the lateral index of inhomogeneity (LII) is low, the 1D interpretation of both Wenner arrays is justifiable. In addition, the averaging of resistances will result in an apparent resistivity curve that is devoid of lateral effects resulting from near-surface inhomogeneities. As demonstrated by the Vrdnik example, 1D inversion is inadequate when the values of LII and processing covariance (PC) are high. The survey in Golubac was conducted using the square array, which produced lower PC values than collinear arrays. Therefore, the quality of the averaged sounding curve was higher. Also, the interpolated values of the Offset Wenner array displayed reasonable accuracy, while the extrapolated values were inadequate when a low resistivity substratum was present.