Two-dimensional water flow through stratified unsaturated porous media : laboratory sand-box experiments

Abstract

Five sand-box experiments were conducted to investigate the behavior of water flow in unsaturated stratified porous media. The hydraulic properties OM and K(0) of the medium and coarse sands used in the experiments were measured with various laboratory columns. Fourteen layers comprised of the medium and coarse sands were alternately layered in a 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 was used to record the tension head distribution during each experiment. The wetting front profiles of the first experiment show the stratified sand affects both the development and dissipation of preferential flow paths. The observed wetting front behavior and an analysis of the possible behavior of the effective hydraulic conductivity at the medium on coarse sand interface qualitatively supports the the concept of saturation dependent anisotropy (Yeh et al., 1985b; and Mantoglou and Gelhar, 1987b). The hydraulic properties of the medium and coarse sands, the boundary and initial conditions of four sand-box experiments, and the results from these experiments can be used to test an unsaturated numerical model.