Adsorption and capillary processes in variably saturated porous media-pore scale hydrostatic and hydrodynamic considerations

This chapter provides a review of progress in pore- and sample-scale liquid retention and liquid-vapor interfacial area modeling. It discusses aspects of the unitary approach for combining adsorptive and capillary contributions, and presents the new pore scale model. The upscaling scheme for representing sample scale retention properties is presented, followed by illustrative examples with measured characteristic data and a discussion of critical soil parameters. The chapter highlights the role of liquid-vapor interfacial area by comparisons of model predictions with limited measurements. It also provides information on hydrodynamic considerations of unsaturated flow in films and comers leading to prediction of hydraulic conductivity of rough rock surfaces and unsaturated porous media. The detailed picture of liquid vapor interfaces under hydrostatic conditions provides a basis for introducing hydrodynamic considerations.