In groundwater " potentiometric surface " is a synonym of " piezometric surface " which is an imaginary surface that defines the level to which water in a confined aquifer would rise were it completely pierced with wells.
22.
Specific storage ( " S s " ) and its depth-integrated equivalent, storativity ( " S = S s b " ), are indirect aquifer properties ( they cannot be measured directly ); they indicate the amount of groundwater released from storage due to a unit depressurization of a confined aquifer.
23.
Aquifers are broadly classified as being either confined or unconfined ( water table aquifers ), and either saturated or unsaturated; the type of aquifer affects what properties control the flow of water in that medium ( e . g ., the release of water from storage for confined aquifers is related to the storativity, while it is related to the specific yield for unconfined aquifers ).
