Depth of Investigation in Measurements of Frequency-Dependent Soil Properties

The use of depth of investigation concept in measurements of frequency-dependent soil properties is examined. It was shown that the median value of the depth of investigation characteristic curve is more practically useful for arrays with perpendicular location of electrodes than the maximum value of the curve. At the same time, when soil is highly inhomogeneous and the measurement array dimensions differ significantly (for the same depth of investigation), there may be appreciable differences in apparent resistivities. In such a case, it is recommended to choose an appropriate electrode array, rather than just a certain depth of investigation.