Estimating Hydraulic Conductivity and Porosity of Soils from Spectral Electrical Response Measurements

Abstract

A procedure is developed to estimate the hydraulic conductivity and porosity of soils from the laboratory measurements of their frequency dependent electrical response (FDER) using inversion schemes and regression models. The FDER (resistivity and phase spectra) of a soil contains valuable information about its porosity, hydraulic conductivity, texture and fluid properties. In this study the FDER of the soil is modeled as a heterogeneous system using the multi-Cole-Cole model. The intrinsic parameters, which innately describe the response of the multi-Cole-Cole model, are retrieved by an inversion scheme and are used in empirical regression models to predict the hydraulic conductivity and porosity. Measurements of hydraulic conductivity, porosity and spectral electrical response of a variety of soil samples at laboratory scale were also performed. Multiple regression analyses suggest that the porosity and permeability can be well predicted by the parameters of the multi-Cole-Cole model. Establishing such direct relationships between parameters characterizing the spectral electrical response of soils and their hydraulic properties may provide a versatile non-invasive methodology of obtaining hydraulic conductivity and porosity of soils using geophysical measurements. This study is the beginning of a new class of geophysics that links the flow properties to the geophysical data.