Water saturation

Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis.

Volumetric water content, θ, is defined mathematically as:

where ${\displaystyle V_{w}}$ is the volume of water and ${\displaystyle V_{\text{wet}}=V_{s}+V_{w}+V_{a}}$ is equal to the total volume of the wet material, i.e. of the sum of the volume of solid host material (e.g., soil particles, vegetation tissue) ${\displaystyle V_{s}}$, of water ${\displaystyle V_{w}}$, and of air ${\displaystyle V_{a}}$.

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