ABSTRACT

The theory and experimental verification of isothermal moisture storage and movement in soils are well developed. Some of the processes such as freezing and thawing, presence of macropore flow channels, swelling and shrinking of soils, and salinity complicate the flow and transport processes through soils by modifying the physical and water transmission properties of porous media. It is generally recognized that during freezing and thawing processes, soil moisture and thermal states of a soil system are coupled. Inadequate understanding of this complex problem of phase changing processes during freezing and thawing and sparsity of development in regions where these processes are significant are some of the reasons why enough progress has not been made in this field. This chapter discusses some of the mathematics of coupled heat and moisture transport models as well the effects of freezing and thawing on soil’s physical properties. The modeling of macropore flow and its effect on infiltration and solute transport through soil profile, characteristics, and water flow in swelling soils, and pressure potentials in saline soils, are also discussed. Another important topic covered in this chapter is waterrepellent soils. This is an important research topic to which an increasing attention has been paid in view of its. This chapter describes hydrological processes in water-repellent soils.