Estimation of unsaturated flow in layered soils with the finite control volume method

Abstract

Water movement in unsaturated soil is described by Richards' equation, which is strongly nonlinear and cannot be solved analytically. For this reason numerical methods such as finite difference and finite element methods have been used to solve it. This paper presents another numerical solution of Richards' equation, based on the finite control volume method. This method has important advantages over other numerical methods, such as conservativeness of the system and flexibility of the grid intervals. To validate the numerical model a series of experiments were carried out in the laboratory in a vertical column of unsaturated two-layered soil (coarse and fine sand). The upper boundary condition was a second kind or Newman one and the lower boundary condition was a third kind or Newton's law condition. The soil water content was measured using the gamma -ray absorption method, while the water pressure in the pore media was measured using a tensiometer system with ceramic cups and pressure transducers. The numerical results of the new computational scheme are in good agreement with the experimental points. Copyright (C) 2001 John Wiley & Sons, Ltd.