A layer of rock or substrate that contains groundwater. Groundwater may either be static or moving through the aquifer.


A layer of rock or substrate that retards, but does not prevent the flow of water to or from an adjacent aquifer; a 'leaky' confining layer.


A layer of rock or substrate of low porosity that obstructs the the flow of water to or from an adjacent aquifer.


Groundwater that is under sufficient pressure to cause it to rise to the surface.


A relatively low area of the earth's surface into which water and sediment flows and accumulates.


The area encompassing all sources and tributaries of a single drainage system.

Confined Aquifer

An aquifer bounded by confining layers or aquitards; the water will rise above the height of the aquifer when released into a well.

Confining Layer

A layer of rock or substrate of relatively low permeability that bounds an aquifer.


A community of living things that interact with each other to some extent and are often interdependent.


Habitat in which freshwater and seawater meet, such as at a river mouth or where fresh groundwater seeps into the sea.

Groundwater dependent ecosystems

Ecosystems that are dependent on groundwater for their existence and health.


Water occurring under the ground in fractures and pore spaces between particles of substrate such as sediment and rock.


The study of groundwater.

Hydrologic Cycle

The constant circulation of water between the earth's surface (land and sea) and the atmosphere. This includes the movement of water by overland surface water flow, groundwater flow under the ground, evaporation and precipitation.


The replenishment of groundwater supplies in an aquifer.


Water from rainfall that flows on the surface of a catchment.


A measure of how much dissolved salt is in water.



Unconfined aquifer

An aquifer that is not enclosed by an upper impermeable layer, allowing the water table to fluctuate.

Water table

The upper surface of the water that saturates layers of rock or sediment in an unconfined aquifer.