Vadose zone is a critical component in ecosystem modeling. This is mainly because a lot of important processes occur within this zone. The location of vadose zone can be best illustrated by:
In ecosystem modeling, most of the carbon/water dynamics are simulated within this zone. First, due to that the soil water is unsaturated, a modified Richard equation must be used to simulate the 3D water flow. However, currently, most modeling work usually only consider the one-dimensional water flow. Second, soil thermal is usually simulated since most processes are influenced by soil temperature dynamics. Third, microbe activities and other chemical reactions are simulated in some scenarios.