ANALYTICAL SOLUTIONS FOR ONE-DIMENSIONAL, TRANSIENT INFILTRATION TOWARD THE WATER-TABLE IN HOMOGENEOUS AND LAYERED SOILS

Analytical solutions describing the transient soil water pressure distributions during one-dimensional, vertical infiltration toward the water table through homogeneous and two-layer soils are derived. Exponential functional forms K = K(s)e-alpha-psi and theta = theta-r + (theta-s - theta-r)e-alpha-psi are used to represent the hydraulic conductivity and pressure relation and the soil water release curve. Steady state profiles are used as initial conditions. Hydraulic behavior of the soils during wetting and drainage processes is discussed in terms of the pressure head and moisture content profiles and temporal variation of the specific discharge. The solutions provide a reliable means of comparing the accuracy of various numerical methods, especially in very dry layered soils.