Several mechanisms are responsible for colloid transport in unsaturated zone in addition to that of saturated zone, such as, liquid-gas interface capture, solid-liquid-gas interface capture, liquid-film straining, and storage in immobile liquid zones. The rate that water will infiltrate into the soil is dependent on textural characteristic of the soil profile, the condition of the soil surface, and the initial moisture content within the
soil profile at the time of the infiltration event. The soil’s textural characteristics determine the saturated hydraulic conductivity of the soil and the water retention or storage characteristics of the soil