Improvements to Estimating Unsaturated Soil Properties from Horizontal Infiltration

Current methods to determine unsaturated soil properties are expensive, difficult, and time‐consuming. A procedure is presented that quickly estimates the unsaturated hydraulic conductivity, diffusivity, water retention, and sorptivity functions from a Bruce–Klute test in conjunction with a semi‐analytic analysis. Data collection was performed using a computer controlled γ‐ray attenuation system to measure moisture content. A computer controlled syringe pump maintained the inlet boundary conditions. Improvements to existing analytical procedures include the independent optimization of van Genuchten soil hydraulic parameters n and α, and a method to optimize the residual moisture content from a single measurement of water potential versus water content. The method was applied to a sandy loam and its strengths and weaknesses are discussed.