MASS CONSERVATION NUMERICAL SCHEME FOR TWO-DIMENSIONAL VARIABLY SATURATED FLOW

Abstract

Moisture movement through unsaturated zone is very important in many branches of engineering such as agricultural engineering, soil science, groundwater engineering etc. The unsaturated zone interacts with flow processes at soil surface as well as with groundwater. Due to complex nature of flow through unsaturated zone, it is difficult to get accurate and mass conserving solution for unsaturated flow problems. The present study comprises of developing a mass conserving numerical model for simulating two-dimensional variably saturated flow. The numerical solution uses fully implicit finite difference, Picard iteration and iterative alternate direction implicit scheme applied to mixed form of variably saturated flow equation. The model is efficient and mass conservative in unsaturated zone. The model uses two different constitutive relationships for hydraulic conductivity-pressure head-moisture content given by Van Genuchten [1980] and Haverkamp [1977]. The simulation provides moisture content and pressure head profiles at discrete times. Sensitivity analysis is performed to study the effect of various soil parameters on the moisture movement through variably saturated