Effective Hydraulic Functions in Layered Porous Media.

Modeling of flow and transport in large scale unsaturated zone is demanding and complicated because soil is heterogeneous. Therefore, upscaling methods, which describe the averaged flow behavior, are often required to model complex hydrological processes. Due to the diagenesis of the soil, heterogeneity is generally more pronounced in the vertical direction than in the horizontal direction. The soil structure can then be considered to be layered. In this study, we investigate effective hydraulic functions in heterogeneous soils consisting of a few distinct layers. Specifically, we examine the hydraulic functions of heterogeneous soils bound by a same capillary pressure at both ends of the domain. The effective hydraulic property functions applicable in predicting moisture flux in heterogeneous soils are numerically determined in terms of p-norm averaging of hydraulic properties of individual layers. Results demonstrate that many factors such as capillary pressure, the structure of the layer formations and the hydraulic property contrast of the layered soils significantly impact the effective hydraulic functions.