Rapid Estimate of Unsaturated Hydraulic Conductivity Function

Abstract

AbstractFrom results of Reichardt, Nielsen, and Biggar and of Russo and Bresler, it is inferred that a laboratory horizontal infiltration experiment with air‐dry soil yields an estimate of the saturated‐unsaturated hydraulic conductivity function given by K(h) = 0.27 m4 (he/h)2.6 or K(θ) = 0.27 m4 [(θ − θd)/(θw − θd)]7.2. Here m = dx/d (t1/2); x is distance to the wetting front and t is infiltration time; θd and θw are water contents of air‐dry and “saturated” soil; h is pore water pressure head, and he is the air entry value of h. These relationships can serve as a general approximation of K(θ) and K(h) in nonsodic stable soils. Field measurements of he and saturated K can also be used to derive K(θ) and K(h).