A comparison of field-monitored and numerically predicted moisture movement in unsaturated soil

This paper presents the results of the application of a numerical model of flow of water in unsaturated soil to simulate real field behaviour. Numerical predictions are compared with field‐monitored results as part of an assessment of the approach adopted. The numerical approach is based on a finite element solution of Richards' theoretical formulation, adopting a finite difference recurrence relationship to model the transient nature of the problem. The field results have been collected by British Gas in Kimmeridge clay at a site in Swindon. The simulation addressed the autumn wetting of the soil during 1983. Comparisons of volumetric moisture content readings from the field and numerical predictions give good correlation. It is concluded that the numerical model has adequately represented field behaviour over the depth of interest. Taken in conjunction with previous results, it is claimed that the model should now be capable of use in a predictive mode.