Acre-foot
The volume of water required to cover 1 acre of land (43,560 square
feet) to a depth of 1 foot. One acre-foot is equal to 325,851 gallons,
which is enough water for a family of four for an entire year.
Aquifer
A geologic formation (soil or rock), group of formations, or part of a
formation capable of storing, receiving and transmitting water. An
aquifer is capable of yielding enough water to support a well or spring.
Conjunctive Use
The combined use of surface and ground waters to serve a particular
purpose. For example, during dry years in a conjunctive use program,
drinking water needs are largely met with groundwater. During wet
years, surface water is the primary sources of drinking water, allowing
the groundwater table to replenish naturally.
Consumptive Use
Water
that is evaporated, transpired by plants, incorporated into products or
crops, consumed by humans or livestock, or otherwise removed from the
immediate water environment. Also referred to as water consumption.
Diversion
A channel
constructed across the land slope to intercept surface runoff and
conduct it to an outlet.
Drainage Basin
The land area
drained by a river.
Evapotranspiration
A
collective term that describes water movement back to the atmosphere as
a result of plant transpiration and evaporation from soil surfaces and
surface water bodies.
Groundwater
Water stored
underground in rock crevices and in the pores of geologic materials
that make up the Earth’s crust.
Groundwater
Recharge
The
replenishment of groundwater by seepage of precipitation and runoff.
Infiltration of precipitation and its movement to the water table is
one form of natural recharge. Also, the volume of water added by this
process.
Injection Well
Refers
to a well constructed for the purpose of injecting treated wastewater
directly into the ground. Wastewater is generally forced (pumped) into
the well for dispersal or storage into a designated aquifer. Injection
wells are generally drilled into aquifers that don’t deliver drinking
water, unused aquifers, or below freshwater levels.
Infiltration
The downward entry
of water into the Earth’s surface.
Infiltration
Capacity
The maximum rate at
which infiltration can occur under specific soil moisture conditions.
Million Gallons Per Day (Mgd)
A
rate of flow of water equal to 133,680.56 cubic feet per day, or 1.5472
cubic feet per second, or 3.0689 acre-feet per day. A flow of one
million gallons per day for one year equals 1,120 acre-feet (365
million gallons).
Overdraft
The
reduction of groundwater storage that occurs when withdrawals from an
aquifer exceed recharge. Sometimes referred to as mining of groundwater.
Percolation
The downward
movement of water through the openings in soil or rock.
Recharge
The
replenishment of groundwater by seepage of precipitation and runoff.
Also stated as the process of addition of water to the saturated zone.
Return Flow
The
amount of water that reaches a surface or groundwater source after it
has been released from the point of use and thus becomes available for
further reuse. Also called return water.
Safe Yield
The
amount of groundwater that can be withdrawn continually from an aquifer
in an economical and legal manner without having any adverse effect on
the groundwater resource or the surrounding environment.
Saturated Zone
The zone
in a soil profile or geologic formation in which all pore spaces are
filled with water.
Surface Water
Water that is on the
Earth’s surface, such as streams, rivers, lakes or reservoirs.
Watershed
The
land area that drains water to a particular stream, river, or lake. It
is a land feature that can be identified by tracing a line along the
highest elevations between two areas on a map, often a ridge.
Water Table
The upper boundary
or top surface of the zone of saturation in a soil profile or geologic
formation.
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