What is specific storage?

Specific storage, also known as storativity or specific yield, is a hydrogeologic term that refers to the amount of water that can be stored or released by a unit volume of an aquifer or porous medium when the water table changes. It is a measure of the ability of a formation to store and transmit water.

Specific storage is expressed in units of volume of water per unit volume of the porous medium per unit change in hydraulic head. It is a dimensionless measure and does not depend on the size of the aquifer or the rate of water movement.

Specific storage is an important parameter used to calculate groundwater flow and aquifer recharge rates. It is also used to help predict the behavior of groundwater systems under different pumping scenarios and to understand how changes in local geology can impact groundwater storage and movement.

The value of specific storage depends on various factors, such as porosity, hydraulic conductivity, and the degree of water saturation in the aquifer. It is typically determined through laboratory tests or field measurements, and can vary widely depending on the characteristics of the aquifer or geological formation being studied.