Hydraulic Conductivity of Saturated Soil Medium through Time-Domain Reflectometry

Time-domain reflectometry (TDR) has been extensively used to study soil behaviors. The objective of this study is to propose a method for measuring hydraulic conductivity using TDR. The dielectric constant deduced from TDR is influenced by the electrical resistance of the medium, and it can be converted into the electrical resistivity of the material. Thus, the theoretical relationship between the dielectric constant and hydraulic conductivity is established because electrical resistivity is a function of hydraulic conductivity. A cell is developed for measuring both the dielectric constant and hydraulic conductivity simultaneously. Three electrodes are used to measure the reflected waveform by using the principle of TDR. The following specimens are used to verify the proposed technique: glass beads, Jumunjin sand, and soil extracted from a field. The dielectric constant is converted into hydraulic conductivity, and it is compared with the value determined by a constant-head experiment for reference. The comparison shows a high similarity. Verification is also carried out through field experiments. This study demonstrates that the proposed method is an alternative method to find the hydraulic conductivity through TDR.