Review of Foreign Study on Two-Phase Flow in Vadose Zone

In traditional study of water flow in vadose zone,little attention is paid to the effect of air entrapment,while this effect is rather important.There take place not only water flow,but also air flow in vadose zone.A better understand of two-phase flow is important to grasp the process of contaminant transport in vadose zone.This paper describes the water flow,air flow and its effect on water flow and the variation of air pressure during the infiltration based on the research in recent decades.The distinction among these results is also analyzed.