Effect of capillary hysteresis and spatial variability of hydraulic conductivity on two dimensional hillslope soil moisture flow

Abstract

Two dimensional soil moisture flow was studied. A laboratory model 1.83 meters long and 0.13 meters wide, 1.22 meters deep at one end and 0.91 meters deep at the other end was used to generate experimental data consisting of water pressure potentials and discharge. Numerical simulations, based on numerical solution of the Richards equation of these experimental conditions were performed and the results compared to the experimental results. Two rainfall events were used in this study: a steady rainfall intensity and an intermittent rainfall of three different intensities. The numerical and experimental results were in agreement only when the effect of capillary hysteresis were incorporated into the numerical simulation. The effect of spatial variability of soil hydraulic conductivity on soil moisture flow was also evaluated. This analysis showed a good agreement of experimental and numerical results when the variability is included in the numerical simulation. Data obtained from the laboratory model and the numerical models are presented in the form of hydrographs and hydraulic head fields.