Improved apparatus for measuring hydraulic conductivity at low water content
A modification of the steady-state centrifuge method (SSCM) for unsaturated hydraulic conductivity ( K ) measurement improves the range and adjustability of this method. The modified apparatus allows mechanical adjustments to vary the measured K by a factor of 360. In addition, the use of different flow-regulating ceramic materials can give a total K range covering about six orders of magnitude. The increment of K adjustment is a factor of about 1.6. This makes it potentially useful for measuring targeted values of K or, through a trial and error procedure, of water content (θ). The range extension afforded by this modification has led to the lowest steady-state K measurement to date: 1.1 × 10 −11 m/s at θ of 0.068 m 3 water/m 3 for a sandy soil of the Delhi series (mixed, thermic Typic Xeropsamment).