Is the vadose zone typically saturated or unsaturated?

The vadose zone is typically characterized as unsaturated. This zone is the area of soil and rock located above the water table, where the pores contain both air and water, but the water is not filled to capacity. In this region, moisture is present in varying amounts depending on factors like precipitation and soil characteristics, but it does not completely saturate the soil or rock. The unsaturated condition of the vadose zone is crucial for several hydrological processes, including water infiltration and the movement of contaminants, which are key considerations in site assessments for underground storage tanks. Understanding the properties of the vadose zone is essential for assessing groundwater pollution risks and establishing remediation techniques where necessary.