Gl ossary Alluvial aquifer An aquifer formed by geo-
Cone of depression The draw down of the
Specific yield Represents the volume of
logic sediments deposited in a stream
potentiometric surface due to the
water that can drain from a unit vol-
channel or on a floodplain.
pumping of a water well. The amount
ume of saturated material by gravity.
of draw down diminishes away from
The storage property of an unconfined
Aquifer Storage and Recovery Storage of
the well so that the resulting configu-
aquifer, whose value is often on the or-
water in a suitable aquifer through
ration of the modified groundwater
der of 0.15.
direct injection in a well when water
surface resembles a cone. Storage coefficient Represents the volume
is available and later recovery of the water from the same well when it is needed.
Confined aquifer An aquifer that is overlain by a confining bed.
of water yielded from the combined elastic properties of water and the aquifer skeleton, from a unit volume of
Artesian head The elevation, above the
Conjunctive use Coordinated use of surface
the aquifer. The storage property of a
top of the aquifer, to which water will
and groundwater supplies to meet de-
confined aquifer, whose value is often
rise in a well completed in a confined
mand so that both sources are used
on the order of 0.0001.
aquifer due to hydrostatic pressure. It
more efficiently. Structural sedimentary basin A topographi-
defines the potentiometric surface. Return flows Surface water or groundwa-
cally low area in the Earth’s crust in
Bedrock aquifer An aquifer within the solid
ter that returns to rivers and shallow
which sediments have accumulated
rock that underlies any unconsoli-
aquifers after being put to beneficial
by transport via streams from the ad-
dated sediment or soil.
use, such as irrigation. In river basins
jacent hills.
all around Colorado, the same water is
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diverted and returned to the river and
Unconfined aquifer An aquifer having a wa-
shallow aquifers three to seven times
ter table, whose surface is at atmo-
or more before it leaves the state.
spheric pressure.
Colorado Foundation for Water Education