The numerical simulation of seasonal soil drying in an unsaturated clay soil

Abstract

AbstractThe results of a numerical simulation of the observed field‐drying behaviour of an unsaturated clay are described. In particular, the simulation of soil drying during the summer of 1983 is addressed.Richards' pressure‐based unsaturated flow formulation is adopted. Transient numerical solutions are achieved by making use of the finite element method coupled with a finite difference timestepping scheme.The application of the algorithm to the simulation of the problem in hand is described. The initial moisture content distribution represents saturated conditions as indicated by field‐measured data. Boundary conditions are determined from an interpretation of meteorological data. A simple method of representing plant root extraction of soil moisture is proposed.Comparisons of numerical results with field‐measured data collected by British Gas are presented. Good correlation is obtained. The numerical simulation is shown to be capable of representing the observed field‐drying behaviour. The complexity of modelling soil drying, as opposed to infiltration, is clearly illustrated by the work presented.