A low cost Automated Test Column to estimate Soil Hydraulic Characteristics in Unsaturated Porous Media

Abstract

Research ArticleThe 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 flowin 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 theHydrus-1D model. The results show that calibrations of electrical resistance probes reasonably match with similar studies, and the maximumerror of calibration of the tensiometers was 4.6% with respect to the full range.Datameasured by the drop counter installed in theATC 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.The authors would like to acknowledge the Minist`ere des Relations Internationales du Qu´ebec, the Consejo Nacional de Ciencia y Tecnolog´ıa (CONACyT 201800), the Consejo Mexiquense de Ciencia y Tecnolog´ıa (COMECYT), the Universidad Aut´onoma del Estado de M´exico (UAEM), the Institut National de la Recherche Scientifique (INRS-ETE),and the Minist`ere d’´Education du Qu´ebec for providing funding and logistical support for this study. The authors are also grateful for the technical support of the laboratory technicians from the Inter-American Centre of Water Resources (CIRA) in Toluca, Mexico