Soil-macropore and layer influences on saturated hydraulic conductivity measured with borehole permeameters

Dye application during an infiltration test demonstrated water movement in macropores and erratic saturated hydraulic conductivity (K_sat) or matric flux potential (φ_m). To evaluate the effects of macropores, cracks, and layered soil on K_sat and φ_m, a finite element solution of the Richards equation was used to simulate infiltration from a borehole. Borehole infiltration (for 2 h) was simulated for a Rozetta silt loam with four configurations. Three methods were tested for calculating K_sat. A negative K_sat was computed using the simultaneous equations approach with the Guelph model when macropores intersected the base of a borehole; negative K_sat or φ_m were produced when cylindrical macropores laterally intersected the borehole wall, depending on the vertical locations of the macropores. Soil with layered hydraulic properties also produced unrealistic K_sat. -from Authors