Stochastic Analysis of Two-Dimensional Unsaturated Flow in a Heterogeneous Soil

The problem of two-dimensional unsaturated flow in a hypothetical heter ogeneous soil is analyzed by Monte Carlo simulation.It is assumed that the flow domain is scale-hetergeneous along the horizontal direction but homogeneous in vertical direction,and the locally soil water flow can be described by the Richards equation.The heterogeneity in the soil hydraulic properties is represented by a scaling factor which is visualized as being arealization of a one-dimensional spatial stochastic function,and the NNM model is used to generate realizations for the scaling factor.The spatial distribution of soil water pressure head is quantified in terms of its first-and second-order moment.The results indicate that the variance of pressure head is a function of its mean,the spatial covariances of pressure head assume their steady state form after a short period of infiltration.