Soil-water interface phenomena

Abstract

Capillarity in porous media (soils) is the basic physical phenomenon responsible for soil-water retention. Without this solid-water interface phenomenon, soil water is transported downward by the force of gravity, thus moving water from precipitation through the top layer of soil to groundwater. Water retention and plant growth would be profoundly limited. In this chapter, capillarity as an important physical phenomenon is described, and the height of the capillary-rise formula is presented. A simplified model of soil as a bundle of capillary tubes is used to explain soil-water behaviour in real soils. The influence of the shape of water menisci on water-vapour pressure just above menisci and capillary-condensation phenomenon are explained. Adsorption and desorption isotherms and the influence of clay minerals on adsorption and desorption phenomena are also mentioned.