Field-Obtained Soil Water Characteristic Curves and Hydraulic Conductivity Functions

Abstract

A test program consisting of two field-scale compacted clay liners (test pads) is conducted to evaluate field-obtained soil water characteristic curves (SWCCs) and hydraulic conductivity functions (k-functions). The test pads are instrumented with volumetric water content and soil water matric potential sensors. Each test pad is subjected to an infiltration cycle, using either a sealed double-ring infiltrometer or a two-stage borehole infiltrometer, followed by a drying cycle. To compare the results from the field-obtained SWCCs and k-functions, laboratory tests are performed on Shelby tube samples. A comparison of the results obtained from field-scale and laboratory techniques illustrates the evidence of hysteresis between the drying and wetting curves. The shapes of the field-obtained and laboratory-obtained SWCCs are similar, although at different volumetric water contents. There is poor agreement between field-obtained and laboratory-obtained k-functions, as reported in other studies; therefore field k-functions are preferential when available.