Aquifer Lithology

Aquifers

Aquifers are rock layers that are:

porous, allowing large quantities of water to be stored; and
permeable, allowing water to move freely.

In general, deep aquifers are those occurring at depths greater than 100 metres.

A confined aquifer is an aquifer that is bounded above and below by impermeable layers. Recharge occurs in zones where the aquifer comes close to the surface.

An unconfined aquifer is the saturated part of a permeable formation that extends to the land surface. Recharge occurs across the whole permeable layer.

Groundwater in shallow aquifers is generally unconfined to semi-confined. Deeper aquifers are generally confined. The shallow, unconfined systems of the sedimentary basins are usually underlain by deep, confined aquifers.

Aquifer Lithology Map

This map shows the four main types of aquifer lithology. It is based on a map originally developed for the Atlas of Victoria (1982).

Aquifer Lithology

The character of the rock affects the movement of groundwater, its quantity and quality. Permeability may be due to the inter-connected spaces between grains in loose and unconsolidated rock such as sand, or to fractures in hard and brittle rock such as granite.

Four types of aquifer are distinguished:

sand and gravel and limestone - predominately inter-granule porosity
volcanic rocks (eg. basalt) and indurated sedimentary rocks (metasediments) and intrusive rocks (eg. granite) - effective porosity is due to fractures in the rock.

See also...
Groundwater Beneficial Use
This page maps the water quality, or Beneficial Use, of groundwater across Victoria, according to published EPA Beneficial Use segments.
Maps are presented for the watertable aquifer, and the three deeper aquifer systems.

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