Zone of Saturation
Definition - What does Zone of Saturation mean?
The zone of saturation is the ground immediately below the water table. The pores and fractures in soil and rocks are saturated with water.
The zone of saturation is less corrosive than the unsaturated zone above the water table. The moisture content in the region is at one extreme while the other extreme is in the dry soil. Maximum corrosion occurs at the intermediate of the two extremes of soil-moisture content.
The zone of saturation is also known as the phreatic zone.
Corrosionpedia explains Zone of Saturation
The zone of saturation can be found anywhere between a few feet to over thousands of feet below the surface. It holds most of the world’s fresh drinking water, which can be accessed from springs, rivers and wells. This water is sometimes polluted by human activity like the use of fertilizers and pesticides, septic tanks and landfills.
The size and depth of this region fluctuates as seasons change, and its levels depend on whether it is a dry or wet period, as well as other factors such as the drawing of water from wells and springs and other human activities.
The reason for the low corrosive atmosphere in the region is the low concentration of oxygen in the soil's moisture content. The little oxygen is not sufficient affect the metal surface, which is a prerequisite for corrosion to occur.
Other factors that may influence corrosion in the zone of saturation are the presence of dissolved substances like the chloride ions, sulphates and other aggressive substances.