Saturated / unsaturated zone

Saturated / unsaturated zone

Saturated zone - is a system with two phases (solid and liquid) where all pores are filled with water.

Unsaturated zone - is a system with three phases (solid, liquid and gas) where only a part of the ground is filled with water.

 

The fundamental difference between saturated and unsaturated zones consists in different hydraulic conductivities.

It can be distinguished:

·         water from soil representing water from the unsaturated zone, and which is the transit bond between matter and substances. These processes are part of a continuous cycle soil-plants-atmosphere.

·         subsurface water level is influenced by rain percolation regime or irrigation water that crosses through the unsaturated zone.

Two cases are distinguished:

1.     in case of an unsaturated environment, hydraulic conductivity varies with soil humidity and water effective pressure, which is negative.
2.      in case of a saturated environment, effective water pressure in soil is positive and depends on the depth of submersion below the free water surface.