Four soil moisture characteristic curve functions evaluated for numerical modeling of sand

Four mathematical representations of a soil moisture characteristic curve were examined for applicability to numerical modeling. The models were: 1) the Campbell equation, 2) the Verma and Brutsaert equation, 3) the van Genuchten equation, and 4) the Hutson and Cass Two-Equation Method. The media that was measured and simulated was a sand-silt mix. The Campbell equation was deemed inappropriate for modeling wet situations and, therefore, not suitable for a numerical model. The remaining soil moisture characteristic curve representations did not result in significant differences in hydraulic head prediction but the execution time for the numerical model varied significantly. The van Genuchten equation best represented observed data.