Confined aquifer

A water-bearing geological formation bounded by low-permeability layers that restrict water movement and may keep groundwater under pressure.

Aquifer: A permeable geological formation that stores and transmits groundwater. A confined aquifer is one boundary-defined kind of aquifer.
Groundwater: Water occupying the pores and fractures beneath Earth's surface. The water stored and transmitted here is groundwater.
Unconfined aquifer: An aquifer whose upper boundary is the water table and is not overlain by a confining layer. Its water table responds directly to infiltration, unlike pressure beneath a confining layer.
Piezometer: A device or narrow well used to measure groundwater hydraulic head at a specific depth. A piezometer measures pressure levels in a confined layer.
Ogallala Aquifer: A large aquifer beneath the Great Plains of the United States, heavily used for irrigation. Its deeper portions include confined conditions, contrasting with widespread unconfined areas.
Hydraulic head: The elevation to which water rises in a well, expressing groundwater's mechanical energy per unit weight. Head reveals the pressure maintained within a confined aquifer.
Porosity: The fraction of a material's volume occupied by pores or voids. Pore space provides the storage capacity of the aquifer.
Leaky aquifer: An aquifer that exchanges water through adjacent low-permeability layers at a measurable rate. It illustrates partial confinement where boundaries permit appreciable leakage.
Groundwater drawdown: A decline in groundwater level or hydraulic head caused by pumping or other drainage. Pumping lowers head and changes pressure across the confined aquifer.
Floridan aquifer system: A carbonate aquifer system supplying groundwater across Florida and parts of neighboring southeastern states. Confinement in parts of this system produces artesian conditions.

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