AUTOMATIC ATOMIZED WATER SPRAY SYSTEM FOR SOIL HYDRAULIC CONDUCTIVITY MEASUREMENTS

Soil hydraulic conductivity, K, as function of volumetric water content, theta, must be known accurately for any quantitative investigation of water and solute transport in unsaturated soil. Direct measurements of K(theta) are hampered by lack of a suitable apparatus to apply small and spatially uniform water flux densities to soil surfaces for extended periods of time. We developed an automatic atomized water spray system that meets these requirements. Results indicate that, with this water spray system, soil hydraulic conductivities between saturation and values approaching 0.1 mm/d can be measured easily, quickly, and accurately. Hydraulic conductivities were a single-valued function of water content, measured simultaneously with time-domain reflectometry, but not of pressure head.