The quality of numerical modeling solution of moisture flow through unsaturated soil, in part, depends on properly described unsaturated soil properties. The variability of Soil Water Characteristic Curve, SWCC, is attributed to hysteresis and difficulties associated with its measurement. The variability of unsaturated soil permeability is contributed to the uncertainty associated with the estimation of this parameter with currently available fit functions, hence a range of reasonable variation was considered. One-dimensional analysis of expansive soil under dry initial conditions (-1500 kPa) was performed; both potential evaporation and infiltration boundary conditions were considered. It was found that small variations in unsaturated soil permeability function result in significantly different modeling outputs while variation in SWCC produced almost identical soil response in terms of soil suction.