In general, water movement in soil is very dynamic and changes from time to time.
Infiltration is the process of water entering the soil surface.
The rate at which water enters an initially dry soil depends upon the rate it is applied, the hydraulic properties of the soil, the initial water content of the soil, and the time since infiltration began. This occurs even if no soil structural changes take place during wetting. This exercise is designed to help us understand why this occurs. Consider a soil which has water ponded on it to a depth of 5 cm. Before ponding, the soil was somewhat dry having a matric potential of -1000 cm.