Mathieu, James T., Jr.; Yeh, T.-C. Jim; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1988-10)
      Five sand tank experiments were conducted to investigate the behavior of unsaturated flow in heterogeneous porous media and to test the recent stochastic theories of Yeh et al. (1985a, b. c) and Mantoglou et al. (1987a, b, c) on flow through unsaturated porous media. The hydraulic properties @(w) and K(0) of the medium and coarse sand used in the experiments were measured with various laboratory columns. Fourteen medium and coarse sands were alternately layered in the 2.38 m long x 1.12 m high x 0.1 m thick sand tank. Water was infiltrated from a point source for three of five experiments and from a channel source for two experiments. An array of 62 tensiometers were used to record the capillary tension head distribution during each experiment. The wetting front profiles for the first experiment show the stratified sand effects both the development and dissipation of preferential flow paths. The experimental results qualitatively support stochastic theory of saturation dependent anisotropy. Three of the five experiments agree with the stochastic result of Yeh et al. (1985a and b) that an increase in the variance of the capillary tension head (soil becomes drier) is proportional to an increase in the mean tension head.