A Low-Cost Automated Test Column to Estimate Soil Hydraulic Characteristics in Unsaturated Porous Media

Abstract

The estimation of soil hydraulic properties in the vadose zone has some issues, such as accuracy, acquisition time, and cost. In this study, an inexpensive automated test column (ATC) was developed to characterize water flow in a homogeneous unsaturated porous medium by the simultaneous estimation of three hydraulic state variables: water content, matric potential, and water flow rates. The ATC includes five electrical resistance probes, two minitensiometers, and a drop counter, which were tested with infiltration tests using the Hydrus-1D model. The results show that calibrations of electrical resistance probes reasonably match with similar studies, and the maximum error of calibration of the tensiometers was 4.6% with respect to the full range. Data measured by the drop counter installed in the ATC exhibited a high consistency with the electrical resistance probes, which provides an independent verification of the model and indicates an evaluation of the water mass balance. The study results show good performance of the model against the infiltration tests, which suggests a robustness of the methodology developed in this study. An extension to the applicability of this system could be successfully used in low-budget projects in large-scale field experiments, which may be correlated with resistivity changes.

A general Beerkan Estimation of Soil Transfer parameters method predicting hydraulic parameters of any unimodal water retention and hydraulic conductivity curves: Application to the Kosugi soil hydraulic model without using particle size distribution data

“…inaccuracy of computing S ) without performing an intensive field campaign, where infiltration tests are combined with measurements of hydraulic parameters in the laboratory and with 2D axisymmetric modelling of the flow below the infiltrometer ( Réfloch et al, 2017 ). It is also recommended that infiltration experiments be combined with innovative non-invasive methods such as Ground Penetrating Radar, which can show the wetting front evolution with time during water infiltration ( Iwasaki et al, 2016;Klenk et al, 2015;Leger et al, 2014aLeger et al, , b, 2015Salas-García et al, 2017 ). Réfloch et al (2017) also showed that monitoring the extension of the soil moisture stain around the infiltration ring with time is valuable for deriving the horizontal and vertical hydraulic parameters.…”

Modeling of Transient Flow in Unsaturated Geomaterials for Rainfall-Induced Landslides Using a Novel Spacetime Collocation Method

“…Governed by nonlinear physical relationships, the Richards equation is a highly nonlinear equation. The SWCC is a major factor that influences the nonlinear physical relationship of the hydraulic conductivity in unsaturated zones [19][20][21][22]. Since the Richards equation is highly nonlinear and an analytical solution can only be provided by some transformations [23], numerical solutions of the Richards equation are commonly used to model the flow process in unsaturated soils.…”

Automated Laboratory Infiltrometer to Estimate Saturated Hydraulic Conductivity Using an Arduino Microcontroller Board

“…To compensate for this, some researchers have preferred to carry out infiltration tests in the laboratory under controlled conditions using test columns, so it is possible to measure not only the inflows, but also the outflows as well as others parameters such as water content, temperature, etc. [18,19].…”