Soil-water characteristic curves and flux boundary problems

The soil-water characteristic curve for an unsaturated soil plays a similar role to the consolidation curve of a saturated soil. It describes the water content present in the soil with respect to matric suction. The slope of the soil-water characteristic curve gives the change of the water volume in the soil with respect to matric suction. The soil-water characteristic curve can be used indirectly to estimate the permeability and shear strength of unsaturated soils. In this paper, emphasis is placed on the hydraulic properties of the soil, soil-water characteristic and permeability, and flux boundary problems. The soil-water characteristic curve exhibits hysteresis on the drying and wetting paths and distinction of the two processes should be taken into account in the determination of permeability and flux boundary problem analyses. The effects of the hysteresis in the soil-water characteristic curves are illustrated with a typical residual soil in Singapore.