Zone of Aeration
The zone between the land surface and water table which may include the capillary fringe. Water in this zone is generally under less than atmospheric pressure, and the voids may contain water, air or other gases.
Why is the unsaturated zone important?
This zone can store appreciable amounts of water on which fauna and flora are dependent. Most groundwater recharge pass through this zone and the nature and thickness of this zone plays an important role in preventing contaminants reaching aquifers.