Rapid Measurement of Field-Saturated Hydraulic Conductivity for Areal Characterization

To provide an improved methodology for characterizing the field-saturated hydraulic conductivity (K(fs)) over broad areas with extreme spatial variability and ordinary limitations oftime and resources, we developed and tested a simplified apparatus and procedure, correcting mathematically for the major deficiencies of the simplified implementation. The methodology includes use of a portable, falling-head, small-diameter (similar to 20 cm) single-ring infiltrometer and an analytical formula for K(fs) that compensates both for nonconstant falling head and for the subsurface radial spreading that unavoidably occurs with small ring size. We applied this method to alluvial fan deposits varying in degree of pedogenic maturity in the arid Mojave National Preserve, California. The measurements are consistent with a more rigorous and time-consuming K(fs) measurement method, produce the expected systematic trends in K(fs) when compared among soils of contrasting degrees of pedogenic development, and relate in expected ways to results of widely accepted methods.