Measurement and Estimation of Water Retention Curves Using Electrical Resistivity Data in Porous Media

Abstract

The soil water retention curve (SWRC) is significant for predicting soil physical properties and solute processes. However, the existing methods for obtaining SWRC are mainly focused on laboratory measurements and have some limitations in efficiency. Thus, this study attempts to build a new SWRC estimation method using soil resistivity data in porous media based on field conditions. The key of obtaining the SWRC is determining the soil moisture and the corresponding soil suction. In this study, soil resistivity and moisture were determined in the laboratory. The relationship between resistivity and soil moisture was then determined by the Archie equation. The quantitative relationship between resistivity and soil suction was constructed using measured data and empirical models. The results show that the Archie equation could be applied to precisely determine the relationship between soil resistivity and soil moisture when the soil resistivity ranged from 100 to 800 Ω · m. Both the van Genuchten (VG) model and the Gardner model were able to fit the SWRC. For the sandy soils involved in this study, the fitting results of the VG model were better than those of the Garden model. The soil resistivity–matrix suction relationship was established to obtain the SWRC by combination with the soil resistivity–water content model. The proposed method was then tested, and it showed great accuracy and reliability in estimating the SWRC and provided a method and theoretical basis for accurately measuring the SWRC on a regional scale.