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Glossary of Terms
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abandoned water right
A water right not put to beneficial use for a number of years, generally five
to seven.
ablation (glacial)
All processes, [melting, evaporation (sublimation),
wind erosion and calving (breaking off of ice masses)], that remove snow or
ice from a glacier or snowfield. The term also refers to the amount of ice removed
by these processes.
acid
A substance that has a pH of less than 7,
which is neutral. Specifically, an acid has more free hydrogen ions (H+) than
hydroxyl ions (OH-).
acid rain
The acidic rainfall that results when rain
combines with sulfur oxides emissions from combustion of fossil fuels (coals).
adaptive management
Sustainable management practices for ecosystems and species that are responsive
to uncertainties and ecological fluctuations, as well as being reversible and
flexible.
adjudication
Judicial process to determine the extent and priority of the rights of all persons
to use water in a river or aquifer system.
agricultural drought
See drought.
alkaline
Sometimes water or soils contain an amount of alkali (strongly basic) substances
sufficient to raise the pH value above 7.0 and be harmful to the growth of crops.
alkalinity
The capacity of water for neutralizing an acid solution.
alluvial aquifer
An aquifer formed by material laid down by physical processes in a river channel
or on a floodplain.
alluvial plain
A level, gently sloping or slightly undulating land surface produced by extensive
deposition of alluvium, usually adjacent to a river that periodically overflows
its banks.
alluvium
Deposits of clay, silt, sand, gravel or other particles that have been deposited
by a stream or other body of running water in a streambed, on a flood plain,
on a delta or at the base of a mountain.
appropriation
The right to use water for a beneficial use or the acquisition of such a right
gained through the process of diverting water and putting it to a beneficial
use.
appropriative water rights
Generally found in western states; have a priority based on the date of first
usage. Created by diversion of water and putting it to beneficial use. In times
of shortage, junior appropriators are cut off while senior appropriators receive
their full allotment.
aquaculture
Farming of plants and animals that live in water, such as fish, shellfish and
algae.
aqueduct
A pipe, conduit or channel designed to transport water from a remote source,
usually by gravity.
aquiclude
An impermeable layer of rock that does not allow water to move through it. Some
shales, for example, have such low permeability that they effectively form an
aquiclude. AQUIFER
An underground bed or layer of earth, gravel or porous stone that yields water
and through which water can pass or is stored. Aquifers supply the water for
wells and springs.
aquifer (hydraulic) diffusivity
Ratio of aquifer transmissivity to storability (or hydraulic conductivity to
specific storage); it indicates how fast a transient change in head will be
transmitted throughout the aquifer system.
aquifer system
Heterogeneous body of inter-bedded permeable and poorly permeable material that
functions regionally as a water-yielding unit; two or more permeable beds are
separated at least locally by confining beds that impede vertical ground water
movement but do not greatly affect the regional hydraulic continuity of the
system; includes both saturated and unsaturated parts of permeable materials.
aquifer yield
Maximum rate of withdrawal sustainable by an aquifer. See yield.
aquifuge
Earth material body that is impervious and unable to absorb water.
aquitard
A part of a geologic formation (or one or more geologic formations) of much
lower permeability than an aquifer and will not transmit water at a rate sufficient
to feed a spring or for economic extraction by a well.
arid
A climate characterized by dryness, variously defined as rainfall insufficient
for plant life, less than 10 inches (254 mm) of annual rainfall.
artesian aquifer
An aquifer in which ground water is confined under significantly greater pressure
than atmospheric pressure. This pressure, called artesian pressure, is generally
due to the weight of water at higher levels in the same zone and is sufficient
to cause water to rise above the level of the aquifer in a well or natural fissure.
An artesian aquifer is bounded above and below by confining beds of less permeable
rock. Synonym: confined aquifer.
artesian water
Ground water that is under pressure when tapped by a well and is able to rise
above the level at which it is first encountered. It may or may not flow out
at ground level. The pressure in such an aquifer is commonly called artesian
pressure and the formation containing artesian water is an artesian aquifer
or confined aquifer.
artesian well
or artesian spring
A well or spring that taps ground water under pressure beneath an aquifuge or
aquiclude so that water rises (though not necessarily to the surface) without
pumping. If the water rises above the surface, it is known as a flowing artesian
well.
artificial recharge
A process where water is put back into ground water storage from surface-water
supplies such as irrigation or induced infiltration from streams or wells.
assignment of water
The transfer of a water right application or permit from one person to another.
This can be done in conjunction with the sale of land.
atmosphere
(1) The gaseous portion of the planet. (2) Standard unit of pressure representing
the pressure exerted by a 29.92-inches (760-mm) column of mercury at sea level
at 45 degrees latitude and equal to 14.696 pounds per square inch (psi) or 101.325
kilopascals (An).
available moisture
or moisture
Portion of water in a soil that can be absorbed by plant roots. It is the amount
of water released from a wet soil between field capacity and the permanent wilting
percentage.
bank storage
Change in storage in an aquifer resulting from a change in stage of an adjacent
surface-water body.
base
A substance that has a pH of more than 7, which is neutral. A base has less
free hydrogen ions (H+) than hydroxyl ions (OH-).
base flow
Stream flow coming from ground water seepage into a stream.
base level
In general, the lowest point in the water table in a given area. Water in the
area flows toward this destination by gravity and hydrostatic pressure.
basin
See drainage basin.
basin yield
Maximum rate of withdrawal that can be sustained by the complete hydrogeologic
system in a basin without causing unacceptable declines in hydraulic head anywhere
in the system or causing unacceptable changes to any other component of the
hydrologic cycle in the basin. See yield.
bed
A layer of rock in the earth, also the bottom of a body of water such as a river,
lake or sea.
bedrock
The solid rock beneath the soil and superficial rock, a general term for solid
rock that lies beneath soil, loose sediments or other unconsolidated material.
beneficial use of water
The use of water for any beneficial purpose. Such uses include domestic use,
irrigation, recreation, fish and wildlife, fire protection, navigation, power,
industrial use, etc. The benefit varies from one location to another and by
custom. What constitutes beneficial use is often defined by statue or court
decisions.
best management practice
A practice or combination of practices determined to be the most practicable
means of preventing or reducing, to a level compatible with water quality goals,
the amount of pollution generated by non-point sources.
biochemical cycle
Chemical interactions among the atmosphere, biosphere, hydrosphere and lithosphere.
Examples are the carbon, oxygen, nitrogen, phosphorus, sulfur and hydrologic
cycles.
biological diversity
or biodiversity
Variety of living organisms at all levels,
from genes to species, populations and communities, including the variety and
hierarchy of habitats and ecosystems that contain different biological communities.
biomass
Total dry organic matter or stored energy content of living organisms that is
present at a specific time in a defined unit (community, ecosystem, crop, etc.)
of the earth's surface.
bioshpere
Portion of earth and its atmosphere that can support life. The part (reservoir)
of the global carbon cycle that includes living organisms (plants and animals)
and life-derived organic matter (litter, detritus). The terrestrial biosphere
includes the living biota (plants and animals) and the litter and soil organic
matter on land and the marine biosphere includes the biota and detritus in the
oceans
brackish water
Water containing too much salt to be useful to people but less salt than ocean
water.
brine
Water that is saturated or partially saturated with salt.
built environment
All human-built-structures.
calcium
The element Ca that occurs as a cation with a double positive charge when dissolved
in water; the major dissolved constituent in the hardness in water.
calibration (model
application)
Process of refining the model representation of the hydrogeologic framework,
hydraulic properties and boundary conditions to achieve a desirable degree of
correspondence between the model simulation and observations of the ground water
system.
cancelled water right
A water right that is made void either at the request of the water right holder
or due to forfeiture.
capacity use rule
In relation to the Central Coastal Plains, a means to regulate water usage through
permits, in order to avoid depleting ground water resources and to indefinitely
maintain availability of those sourced.
capillary action
The means by which liquid moves through the porous spaces in a solid, such as
soil, plant roots and the capillary blood vessels in our bodies due to the forces
of adhesion, cohesion and surface tension. Capillary action is essential in
carrying substances and nutrients from one place to another in plants and animals.
capture
Water withdrawn artificially from an aquifer derived from a decrease in storage
in the aquifer, a reduction in the previous discharge from the aquifer, an increase
in the recharge or a combination of these changes. The decrease in discharge
plus the increase in recharge is termed capture. Capture results in reduced
surface flows.
carbonate
The anionic constituent CO3 that has two negative charges as dissolve din water
or present in a mineral.
carbonate mineral
A class of minerals. Calcite is calcium carbonate (CaCO3). Dolomite is calcium-magnesium
carbonate [CaMg(CO3)2]. The mineral dolomite, less common, is the principal
mineral in the rock dolomite, sometimes referred to as a dolostone.
carbon cycle
All parts (reservoirs) and fluxes of carbon; usually thought of as a series
of the four main reservoirs of carbon interconnected by pathways of exchange.
The four reservoirs (regions of the earth in which carbon behaves in a systematic
manner) are the atmosphere, terrestrial biosphere (usually includes freshwater
systems), oceans and sediments (includes fossil fuels). Each of these global
reservoirs may be subdivided into smaller pools ranging in size form individual
communities or ecosystems to the total of all living organisms (biota). Also
defined as carbon exchanges from reservoir to reservoir by various chemical,
physical, geological and biological processes.
central coastal plain
Eastern region of North Carolina which includes Beaufort, Carteret, Craven,
Duplin, Edgecombe, Greene, Jones, Lenoir, Martin, Onslow, Pamlico, Pitt, Washington,
Wayne and Wilson counties.
certify (also
see perfect)
The actions of a water user to bring an appropriation right into final form
by the completion of diversion works and application of water to the proposed
use in accordance with the approved water-right application.
citizen monitoring
A program conducted by civic or student volunteers involving the collection,
management and dissemination of environmental information.
climate
Generalized weather at a given place on earth over a long period of time (usually
decades), a long-term average of weather. Compare weather.
climate change
Long-term fluctuations in temperature, precipitation, wind and all other aspects
of the earth's climate. External processes, such as solar-irradiance variations,
variations of the earth's orbital parameters (eccentricity, precession and inclination),
lithosphere motions and volcanic activity, are factors in climatic variation.
Internal variations of the climate system also produce fluctuations of sufficient
magnitude and variability to explain observed climate change through the feedback
processes interrelating the components of the climate system.
climatic year
12-month period from July 1 and ending the following June 30, used in the collection
of precipitation data. Designated by the calendar year in which the climatic
year ends.
comment period
Time provided for the public to review and comment on a proposed EPA action
or rule after it is published in the Federal Register.
commercial water use
Water for motels, hotels, restaurants, office buildings, other commercial facilities
and institutions. The water may be obtained from a public supply or may be self
supplied. See also public supply and self-supplied water.
condensation
The process of airborne water vapor turning into liquid water. Water drops on
the outside of a cold glass of water are condensed water. Condensation is the
opposite process of evaporation.
cone of depression
A cone-shaped depression in the water table around a well or a group of wells,
created by withdrawing ground water more quickly than it can be replaced.
confined aquifer
An aquifer that is bounded above and below by confining layers. Because of the
pressure created in a confined aquifer, the water level in a well drilled into
a confined aquifer will rise above the top of the aquifer and, in some instances,
above the land's surface.
confined ground water
Ground water lying beneath an aquiclude or an aquifuge. It is artesian if the
water levels in wells are above the top of the aquifer.
confining bed
A layer of relatively impermeable (i.e.,
incapable of transmitting fluids) material overlying an aquifer.
conservation
Management of water resources to eliminate waste or maximize efficiency of use.
conservation of matter
See mass balance.
conservation storage
Storage of water in a reservoir for later release for useful purposes such as
municipal and industrial water supply, water quality or irrigation.
consumptive use
or water consumed
That part of water withdrawn that is evaporated, transpired by plants, incorporated
into products or crops, consumed by humans or livestock or otherwise removed
from the immediate water environment.
contact spring
A type of gravity spring whose water flows to the land surface from permeable
rocks that are underlain by less permeable rocks, preventing the downward movement
of water.
conveyance loss
Water that is lost in transit from a pipe, canal, conduit or ditch by leakage
or evaporation. Generally, the water is not available for further use: however,
leakage from an irrigation ditch, for example, may percolate to a ground water
source and be available for further use.
correlative rights
Certain rights of landowners over a common ground water basin are coequal or
correlative, so that any one owner cannot take more than his share even if the
rights of others are impaired.
crop rotation
Successive planting of different crops in the same field over a period of years,
usually to reduce the pest population or to prevent soil exhaustion.
cubic feet per second (cfs)
A rate of the flow, in streams and rivers, for example. It is equal to a volume
of water one foot high and one foot wide flowing a distance of one foot in one
second. One "cfs" is equal to 7.48 gallons of water flowing each second. As
an example, if your car's gas tank is 2 feet by 1 foot by 1 foot (2 cubic feet),
then gas flowing at a rate of 1 cubic foot/second would fill the tank in two
seconds.
dam
A structure of earth, rock or concrete designed to form a basin and hold water
back to make a pond, lake or reservoir.
depth to water
The depth of the water table below the earth's surface.
desertification
Progressive destruction or degradation of vegetation cover, especially in arid
and semiarid regions bordering existing deserts. Overgrazing of rangelands,
large-scale cutting of forests and woodlands, drought and burning of extensive
areas all serve to destroy or degrade the land cover. The climatic impacts of
this destruction include increased albedo leading to decreased precipitation,
which in turn leads to less vegetation cover; increased atmospheric dust loading
could lead to decreased monsoon rainfall and greater wind erosion and/or atmospheric
pollution.
desalinization
The process of salt removal from sea or brackish water.
dike (also dyke)
An artificial watercourse (ditch) or a bank, usually of earth, constructed to
control or confine water (levee); raised causeway. DIP
In geology, dip is the angle at which a rock layer is inclined relative to the
horizontal.
discharge
Movement of ground water from the subsurface to the land surface, usually from
a spring or to a marsh, river or stream.
discharge area
An area where ground water is lost naturally from an aquifer through springs,
seeps or hydraulic connection to other aquifers. The water leaving the aquifer
is called discharge.
discharge permit
A state permit issued to allow the discharge of effluent into waters of the
state.
dissolved oxygen (DO)
The amount of oxygen dissolved in water or sewage. Concentrations of less than
5 parts per million can limit aquatic life or cause offensive odors. Low DO
is generally due to excessive organic matter present in water as a result of
inadequate waste treatment and runoff from agricultural or urban land.
distribution of water
Management of water that allows users to receive the amount of water to which
they are entitled by law and as supply permits.
diversion
Physical removal of surface water from a channel, also the act of bringing water
under control by means of a well, pump or other device for delivery and distribution
for a proposed use.
domestic consumption (use)
Water used for household purposes such as drinking, food preparation, bathing,
washing clothes and dishes, flushing toilets and watering lawns and gardens.
It is the quantity or quantity per capita, of water consumed in a municipality
or district for domestic uses or purposes during a given period. It sometimes
encompasses all uses, including the quantity wasted, lost or otherwise unaccounted
for. Also called residential water use. The water may be obtained from a public
supply or may be self-supplied. About 85% of domestic water is delivered to
homes by a public-supply facility, such as a county water department. About
15% of the Nation's population supplies their own water, mainly from wells.
downgradient
In reference to the movement of ground water, the "downstream" direction from
a point of reference (e.g., a well).
downstream
In the direction of the current of a stream.
drainage area
A specific stream location, measured in a horizontal plane, enclosed by a topographic
divide from which direct surface runoff from precipitation normally drains by
gravity into the stream above the specified location.
drainage basin
Land area where precipitation runs off into streams, rivers, lakes and reservoirs.
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. Large drainage basins,
like the area that drains into the Mississippi River contain thousands of smaller
drainage basins. Also called a "watershed."
drawdown
Lowering of the ground water surface or the piezometric pressure caused by pumping,
measured as the difference between the original ground water level and the current
pumping level after a period of pumping.
drinking water standards
Standards established by state agencies, the U.S. Public Health Service and
the EPA for the quality of water used for drinking in the U.S.A.
drip irrigation
A common irrigation method where pipes or tubes filled with water slowly drip
onto crops. Drip irrigation is a low-pressure method of irrigation and less
water is lost to evaporation than high-pressure spray irrigation.
drought
(1) Interval of time, generally of the order of months or years in duration,
during which the actual moisture supply at a given place consistently falls
short of the climatically expected or climatically appropriate moisture supply
(meteorological drought); (2) A condition that occurs only when available soil
moisture is inadequate to meet evaporative demand by plants (agricultural drought);
(3) a period of below-normal stream flow (hydrological drought).
Earth Summit
See UNCED.
ecosystem
Biological communities that interact with the physical and chemical environment
as a unified system, while simultaneously interacting with adjacent ecosystems
and the atmosphere.
ecological or
ecosystem functions
Processes among and within the various biological, chemical and physical components
of an ecosystem that consist of specific activities or flows, such as nutrient
cycling, biological productivity, hydrology and sedimentation; dynamic and sequential
interactions that characterize the evolution of the system, such as exploitation,
conservation, release and reorganization and the cumulative effect of these
processes and interactions, such as the ability of ecosystems to support life.
Ecological functions that are currently perceived to support and protect the
human activities of production and consumption or affect overall well-being
in some way, thus impacting human welfare and even existence.
ecotone
Transitional zone in which one type of ecosystem tends to merge with another
ecosystem.
effective precipitation (rainfall)
The part of precipitation that produces runoff, also precipitation falling on
an irrigated area that is effective in meeting the requirements of consumptive
use.
effluent
Any substance, particularly a liquid, that enters the environment from a point
source. Generally refers to wastewater from a sewage-treatment or industrial
plant.
effluent stream
Stream or reach of a stream whose flow is increased by inflow of ground water;
a gaining stream.
environment
Sum of all external conditions affecting the life, development and survival
of an organism.
environmental sustainability
Widely espoused goal that seeks to improve human needs and ensure the sinks
for human wastes are not exceeded, in order to prevent harm to humans. Environmental
sustainability means natural capital must be maintained, both as a provider
of inuts ("sources") and as a sink for wastes. This means holding the scale
of the human economic subsystem to within the biophysical limits of the overall
ecosystem on which it depends. Environmental sustainability needs sustainable
production and sustainable consumption. On the sink side, this translates into
holding waste emissions within the assimilative capacity of the environment
without impairing it. On the source side, renewable harvest rates of must be
kept within regeneration rates. Non-renewables cannot be made fully sustainable,
but quasi-environmental sustainability can be approached for non-renewables
by holding their depletion rates equal to the rate at which renewable substitutes
can be created. See also sustainable development.
ephemeral flow
When water flows in a channel only after precipitation.
erosion
The wearing away, breaking down or dissolving of rock and other material by
wind or water. The eroded material is often carried off and deposited in other
areas. Types of erosion include solution, corrosion and abrasion. Most limestone
and gypsum caves are formed mainly by solution. Shelter caves and many sandstone
caves are formed by abrasion.
estuary
The seaward end or widened funnel-shaped tidal mouth of a river valley where
freshwater comes in contact with seawater and where tidal effects are present.
evaporation
The process of liquid water becoming water vapor, including vaporization from
water surfaces, land surfaces and snow-fields, but not from leaf surfaces. See
transpiration.
evapotranspiration
A collective term that includes water discharged to the atmosphere because of
evaporation from the soil and surface-water bodies and from plant transpiration.
See also evaporation and transpiration.
field capacity
The capacity of soil to hold water.
fixed ground water
Water held in saturated material with pore spaces so small that it is permanently
attached to the pre-walls or moves so slowly that it is usually not available
as a source of water for pumping.
flood
An overflow of water onto lands used or usable by man and not normally covered
by water. Floods have two essential characteristics: The inundation of land
is temporary; and the land is adjacent to and inundated by overflow from a river,
stream, lake or ocean.
flood, 100-year
A 100-year flood does not refer to a flood that occurs once every 100 years,
but to a flood level with a 1 percent chance of being equaled or exceeded in
any given year.
flood plain
A strip of relatively level and normally dry land bordering a stream, river
or lake that is covered by flood water. It is built of sediment carried by the
stream and dropped when the water has flooded the area. It's called a water
flood plain if it overflows in times of high water or a fossil flood plain if
it is beyond the reach of the highest flood.
flood stage
The elevation at which overflow of the natural banks of a stream or body of
water begins in the reach or area in which the elevation is measured
floodway
A part of the flood plain. The channel of
a river or stream; the parts of the flood plains adjoining the channel that
are reasonably required to carry and discharge the flood water or flood flow
of any river or stream.
flowing well or
spring
A well or spring that taps ground water under pressure so that water rises without
pumping. If the water rises above the surface, it is known as a flowing well.
"first in time, first in right"
A phrase indicating that older water rights have priority over recent rights
if there is not enough water to satisfy all rights.
flow duration curve
Graph of stream discharge versus the percentage of time the flow exceeds that
stream discharge.
flowing artesian well
See artesian well.
flowstone
Caves formed by flowing water; includes bacon (banded flowstone that resembles
bacon and forms along sloping cave walls), rimstone dams, travertine and columns.
flux
Refers to the rate of flow; the quantity of material or energy transferred through
a system or a portion of a system in a unit time and is called mass flux. If
the moving matter is a fluid, the flux may be measured as volume of fluid moving
through a system in a unit time and is called volume flux. For most applications,
we desire to know the flux per unit area of a system rather than the flux of
the entire system; the flux per unit area is called the flux density.
forfeited water right
A water right canceled because of several consecutive years of nonuse.
free ground water
Unconfined ground water whose upper surface is a free water table.
freshwater
Water that contains less than 1,000 milligrams per liter (mg/L) of dissolved
solids; generally, more than 500 mg/L of dissolved solids is undesirable for
drinking and many industrial uses.
gage height
The height of the water surface above the gage datum (zero point); often used
interchangeably with the more general term, stage, although gage height is more
appropriate when used with a gage reading.
gaging station (gauging)
A site on a stream, lake, reservoir or other body of water where observations
and hydrologic data are obtained. The U.S. Geological Survey measures stream
discharge at gauging stations.
gaining stream
A stream that receives ground water discharge from the zone of saturation.
geology
The study of the earth, what it's made of and how it changes over time.
glacial drift
Sediment and rocks transported by glaciers and deposited directly on the land
or indirectly in streams, lakes and oceans. It consists of a mixture of clay,
silt, sand, gravel and boulders ranging in size and shape.
glacier
A huge mass of ice formed on land by the
compaction and re-crystallization of snow that moves very slowly down slope
or outward due to its own weight.
granular aquifer
An aquifer composed of discrete grains of material (usually sand and/or gravel)
in which ground water flows through the spaces (pores) between the grains (inter-granular
flow); said to have a primary porosity and permeability, as contrasted with
secondary porosity and permeability that results from fracturing, etc. Flow
through a granular aquifer is inter-granular flow.
greenhouse effect
Popular term used to describe the roles of water vapor, carbon dioxide and other
trace gases in keeping the earth's surface warmer than it would be otherwise.
These "radiatively active" gases are relatively transparent to incoming short
wave radiation but are relatively opaque to outgoing long wave radiation. The
latter radiation would otherwise escape to space, however these gases become
trapped within the lower levels of the atmosphere. The subsequent re-radiation
of some of the energy back to the surface maintains surface temperatures higher
than they would be if the gases were absent. There is concern that increasing
concentrations of greenhouse gases, including carbon dioxide, methane and manmade
chlorofluorocarbons may enhance the greenhouse effect and cause global warming.
greenhouse gases
Gases, including water vapor, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons
and ozone that insulate the earth; allowing sunlight through to the earth's
surface while trapping outgoing radiation. Also see greenhouse effect and trace
gas.
graywater
Water that has been used for showering, clothes washing and faucet uses. Kitchen
sink and toilet water are excluded. This water has excellent potential to be
reused (for example, as irrigation for yards).
ground water
(1) Water that flows or seeps downward to saturate soil or rock supplying springs
and wells. The upper surface of the saturate zone is called the water table.
(2) Water stored underground in rock crevices and in the pores of geologic materials
that make up the Earth's crust.
ground water basin
Geologically and hydrologically defined areas that contain one or more aquifers
that store and transmit water and yield significant quantities of water to wells.
ground water, confined
Ground water under pressure significantly greater than atmospheric, with its
upper limit the bottom of a bed with hydraulic conductivity distinctly lower
than the material in which the confined water occurs.
ground water flow model
A mathematical model that represents a site-specific ground water flow system.
ground water flow system
Set of ground water flow paths with common recharge and discharge areas. Flow
systems are dependent on both the hydro-geologic characteristics of the soil/rock
material and landscape position. Areas of steep or undulating (hummocky) relief
tend to have dominant local-flow systems (discharging in nearby topographic
lows such as a pond or stream). Areas of gently sloping or nearly flat relief
tend to have dominant regional-flow systems (discharging at much greater distances
than local systems in major basin topographic lows or oceans.)
ground water hydrograph
See hydrograph.
ground water law
The common law doctrine of riparian rights and of prior appropriation as applied
to ground water.
ground water mining
Pumping ground water from a basin at a rate that exceeds safe yield, thereby
extracting accumulated ground water over a long period of time.
ground water overdraft
Pumping of ground water for consumptive use in excess of safe yield.
ground water recharge
Water inflow to a ground water reservoir from the surface. 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.
ground water reservoir
An aquifer or aquifer system in which ground water is stored. The water may
be placed in the aquifer by artificial or natural means.
ground water storage
(1) quantity of water in the saturated zone or, (2) water available only from
the storage as opposed to capture.
ground water storage reserves
Sum of live and dead storage reserves; live storage reserves are situated above
the aquifer outlet or discharge area and can be depleted by natural discharge
drainage and also recovered by pumping; dead storage reserves can be recovered
only by pumping after the live reserves have been exhausted.
ground water, unconfined
Water in an aquifer that has a water table that is exposed to the atmosphere.
hard water
See hardness.
hardness
(1) Water-quality parameter that indicates the level of alkaline salts, principally
calcium and magnesium; expressed as equivalent calcium carbonate (CaCO3). Hard
water is evidenced by the increased quantities of soap, detergent or shampoo
necessary to lather. (2) In mineralogy, the degree of hardness of a mineral
is an aid in identification. Geologists have assigned numbers to the hardness
of several minerals; in this hardness scale, softer minerals are assigned a
low mineral and the harder minerals a higher number.
headwater(s)
(1) The source and upper reaches of a stream; also the upper reaches of a reservoir.
(2) The water upstream from a structure or point on a stream. (3) The small
streams that come together to form a river. Also may be thought of as any and
all parts of a river basin except the mainstream river and main tributaries.
headgate
A gate that controls water flow into irrigation
canals and ditches. A water master regulates the head gates during water distribution
and posts head gate notices declaring official regulations.
"highest and best use"
The classification of water based on analysis of the greatest needs of the future.
Certain quantities are reserved for appropriation according to the classification.
holding pond
A small basin or pond designed to hold sediment laden or contaminated water
until it can be treated to meet water quality standards or be used in some other
way.
hydraulic continuity
Property of the rock framework on a given time scale whereby a change in hydraulic
head in any point of the region can cause a head change in any other point of
the same region by means of pressure transfer through the rock pores and within
a time interval measurable at that time scale.
hydraulic gradient
Slope of the water table or potentiometric surface. The change is static head
per unit of distance in a given direction. If not specified, the direction generally
is understood to be the maximum rate of decrease in head.
hydraulic head
or static head
Height that water in an aquifer can raise itself above an (arbitrary) reference
level (or datum); generally measured in feet. When a borehole is drilled into
an aquifer, the level at which the water stands in the borehole (measured with
reference to a horizontal datum such as sea level) is, for most purposes, the
hydraulic head of water in the aquifer. This term defines how much energy water
possesses. Ground water possesses energy mainly by virtue of its elevation (elevation
head) and of its pressure (pressure head). See also hydrostatic head. When ground
water moves, some energy is dissipated and therefore a head loss occurs.
hydraulic potential
See soil-water potential.
hydraulically connected
A condition in which ground water moves easily between aquifers in direct contact.
An indication of this condition is the water levels in both aquifers are approximately
equal.
hydrilla
is a submersed freshwater herb that, as an invasive non-native weed, often forms
dense stands from the bottom to the top of the water, sprawling across the surface,
although it also found as detached drifting mats. Hydrilla was once cultivated
and sold as an aquarium plant.
hydro
The prefix denoting water or hydrogen.
hydroelectric power water use
The use of water in the generation of electricity at plants where the turbine
generators are driven by falling water.
hydrogeology
The study of ground water and its relationship to geology; sometimes known as
geohydrology.
hydrograph
Graph showing stage, flow, velocity or other characteristics of water with respect
to time. A stream hydrograph commonly shows rate of flow; a ground water hydrograph
shows water level or head.
hydrologic budget or balance
Accounting of the inflow to, outflow from and storage in a hydrologic unit such
as a drainage basin, aquifer, soil zone, lake or reservoir; the relationship
between evaporation, precipitation, runoff and the change in water storage,
expressed by the hydrologic equation.
hydrologic cycle
The complete cycle that water can pass through, beginning as atmospheric water
vapor, turning into precipitation and falling to the earth's surface, moving
into aquifers or surface water and then returning to the atmosphere via evapotranspiration.
hydrologic equation
Equation that balances the hydrologic budget.
hydrological drought
See drought.
hydrology
The study of the characteristics and occurrence of water and the hydrologic
cycle. Hydrology concerns the science of surface and ground waters, whereas
hydrogeology principally focuses on ground water.
hydrostatic head
Height above a standard datum of the surface of a column of water or other liquid
that may be supported by the (hydro) static pressure at a given point.
hydrostatic pressure
Pressure exerted by water at any given point in a body of water at rest.
impoundment
A body of water such as a pond or sludge, confined by a dam, dike, floodgate
or other barrier. It is used to collect and store water for future use.
impermeable layer
A layer of solid material, such as rock or clay, that does not allow water to
pass through.
induced infiltration or
induced recharge
Recharge to ground water by infiltration, either natural or human-made, from
a body of surface water as a result of the lowering of the ground water hydraulic
head below the surface-water level.
industrial water use
Water used for industrial purposes such as fabrication, processing, washing
and cooling, includes such industries as steel, chemical and allied products,
paper and allied products, mining and petroleum refining. Nationally, water
for industrial uses comes mainly (80%) from self-supplied sources, such as local
wells or withdrawal points in a river, but some water comes from public-supplied
sources, such as the county/city water department.
infiltration
The gradual downward flow of water from the surface into soil material.
influent stream
Stream or reach of stream that loses water into the ground, also known as a
losing stream.
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.
inorganic
Not made or derived from living matter. Minerals are inorganic.
instream use
Use of water that does not require withdrawal or diversion from its natural
watercourse, for example, the use of water for navigation, recreation and support
of fish and wildlife.
insurgence
A sinkhole opening that permits flowing surface water to be captured and transported
underground, to later reemerge as a spring (resurgence). Includes piracy openings.
integrated watershed management
Process of formulating and implementing a course of action involving natural
and human resources in a watershed, taking into account the social, political,
economic and institutional factors operating within the watershed and the surrounding
river basins and other relevant regions to achieve specific social objectives.
Typically this process would include (1) establishing watershed- management
objectives, (2) formulating and evaluating alternative resource-management actions
involving various implementation tools and institutional arrangements, (3) choosing
and implementing a preferred course of action and (4) thorough monitoring of
activities and outcomes, evaluating performance in terms of degrees of achievement
of the specified objectives. See also watershed
approach.
interbasin transfer
The physical transfer of water from one watershed to another.
interflow
See underflow.
inter-generational equity
Extent to which the economic opportunities available to the current generation
are also available to future generations; for example, whether activities undertaken
by the current generation lead to irreversible loss of biodiversity and increasing
ecological scarcity today will adversely affect future generations' welfare
and even threaten their existence.
intermittent flow
Surface water flowing only during periods of seasonal runoff.
interrupted flow
Water flowing alternatively on the channel surface in some stream stretches
and disappearing underground in others.
intra-generational equity
Extent to which the economic opportunities available to the current (or a future)
generation are equally available to all members of that generation; for example,
whether the gains from irreversible loss of biodiversity and increased ecological
scarcity are enjoyed disproportionately by some human populations and societies
and the costs borne disproportionately by others.
instrinsic permeability
Quantitative measure of fluid-transmitting ability of a porous medium relative
to the size and interconnectedness of the void openings. See also permeability.
intrinsic value
Having value or "worth," in itself, regardless of whether it serves as an "instrument"
for satisfying individuals' needs and preferences; for example, many more arguments
for preserving biodiversity are based on the premise that organisms should be
"saved" from extinction because all living entities have a fundamental intrinsic
worth.
intrusion
An igneous rock formed from magma that pushed its way through other rock layers.
Magma often moves through rock fractures, where it cools and hardens.
instrusion of saltwater
The saltwater movement from bedrock into the overlying High Plains or alluvial
aquifer. The source of the saltwater is dissolution of rock salt in Permian
rocks in the subsurface.
irrigation
The controlled application of water for agricultural purposes through manmade
systems to supply water requirements not satisfied by rainfall
irrigation water use
Water application on land to assist in the growing of crops and pastures or
to maintain vegetative growth in recreational lands, such as parks and golf
courses.
instream use
Water that is used, but not withdrawn, from a ground- or surface-water source
for such purposes as hydroelectric power generation, navigation, water-quality
improvement, fish propagation and recreation, sometimes called non-withdrawal
use or in-channel use.
kilowatthour (kwh)
A power demand of 1,000 watts for one hour. Power company utility rates are
typically expressed in cents per kilowatt-hour.
laminar flow
Type of flow in which the fluid particles (i.e. small "parcels" of fluid, bigger
than molecules but small in relation to the passageway through which the fluid
is flowing) all move smoothly more or less in the same direction as the bulk
of the fluid. Laminar flow typically occurs when fluid is moving very slowly
through small openings (like capillary tubes) or in very thin sheets.
leaching
The process by which soluble materials in the soil, such as salts, nutrients,
pesticide chemicals or contaminants, are washed into a lower layer of soil or
are dissolved and carried away by water.
levee
A natural or manmade earthen obstruction along the edge of a stream, lake or
river, usually used to restrain the flow of water out of a riverbank.
livestock water use
Water used for livestock watering, feed lots, dairy operations, fish farming
and other on-farm needs.
local flow system
See ground water flow system.
losing stream
A stream that contributes water to the zone of saturation, recharging the ground
water.
locally important aquifer
An aquifer that is moderately productive, i.e. capable of yielding enough water
to boreholes or springs to supply villages, small towns or factories. These
are divided into: Sand/gravel aquifers (Lg); Bedrock aquifers which are generally
moderately productive (Lm); and Bedrock aquifers that are moderately productive
only in local zones (LI).
marine
Relating to the sea, native to or formed by the sea.
maximum contaminant level (MCL)
The designation given by the U.S. Environmental Protection Agency (EPA) to water-quality
standards promulgated under the Safe Drinking Water Act. The MCL is the greatest
amount of a contaminant that can be present in drinking water without causing
a risk to human health.
membrane
A plastic material used in the electro dialysis and reverse osmosis processes.
Electric current is the driving force that moves salt ions through solution
in electro dialysis and hydraulic pressure the driving force in reverse osmosis.
meteorological drought
See drought.
meteorology
See atmosphere.
MG/L
Milligrams of a substance dissolved in one liter of water. The value is essentially
the same as a part per million in freshwater because one liter of distilled
water weighs one million milligrams (one kilogram).
milligrams per liter (MG/L)
A unit of the concentration of a constituent in water or wastewater. It represents
0.001 gram of a constituent in 1 liter of water. It is approximately equal to
one part per million (PPM).
million gallons per day (MGD)
A rate of water flow 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).
minimum desirable streamflows (MDS)
Under Kansas water law, stream flows that maintain or preserve in-stream uses
of water quality, fish, wildlife, aquatic life, recreation and aesthetics from
unacceptable stream depletions by future consumptive appropriations. Minimum
desirable stream flows will not be preferred to vested and senior appropriation
rights filed prior to their enactment nor will they be maintained through all
drought conditions.
mining (as it
pertains to water)
The process, deliberate or inadvertent, of extracting ground water from a source
at a rate the ground water level declines persistently, threatening actual exhaustion
of the supply.
mining water use
Water use during quarrying rocks and extracting minerals from the land.
monitoring well
Non-pumping well used primarily for drawing water-quality samples; also for
measuring ground water levels.
municipal water system
A water system that has at least five service connections or which regularly
serves 25 individuals for 60 days; also called a public water system
natural flow
The rate of water movement past a specified point on a natural stream. The flow
comes from a drainage area where no stream diversion is caused by storage, import,
export, return flow or change in a consumptive use caused by man-controlled
modifications to land use. Natural flow rarely occurs in a developed country.
natural recharge
Naturally occurring water added to an aquifer. Natural recharge generally comes
from snowmelt and precipitation or storm runoff.
nephelometric turbidity unit (NTU)
A unit of measure for the turbidity of water. Essentially, a measure of the
cloudiness of water as measured by a nephelometer. Turbidity based on the amount
of light reflected off particles in the water.
non-point source pollution (NPS)
Pollution discharged over a wide land area, not from one specific location.
These are forms of diffuse pollution caused by sediment, organic nutrients and
toxic substances originating from land-use activities carried to lakes and streams
by surface runoff. Non-point source pollution is contamination that occurs when
rainwater, snowmelt or irrigation washes off plowed fields, city streets or
suburban backyards. As this runoff moves across the land surface, it picks up
soil particles and pollutants, such as nutrients and pesticides.
normal
Average value of a meteorological variable (such as precipitation or temperature)
over a fixed period of years usually recognized as standard. In the United States,
30-year normals are frequently used.
observation well
Non-pumping well used primarily for observing the elevation of the water table
or the piezometric pressure; also to obtain water-quality samples.
offstream use
Water withdrawn or diverted from a ground- or surface-water source for public-water
supply, industry, irrigation, livestock, thermoelectric power generation and
other uses. Sometimes called off-channel use or withdrawal.
organic matter
Plant and animal residues or substances made by living organisms, based upon
carbon compounds.
osmosis
The movement of water molecules through a thin membrane. The osmosis process
occurs in our bodies and is also one method of desalinizing saline water.
outcrop
That part of a rock unit exposed at the earth's surface.
outfall
The place where a sewer, drain or stream discharges: the outlet or structure
through which reclaimed water or treated effluent is finally discharged to a
receiving water body.
overdraft
(1) )Pumping of ground water for consumptive use in excess of safe yield; (2)
The condition of a ground- water basin where the amount of water withdrawn exceeds
the amount of water captured over the basin over a period of time, the use of
water in excess of the perennial yield.
overpumping
A new phenomenon, one largely confined to the last half century. Only since
the development of powerful diesel and electrically driven pumps have we had
the capacity to pull water out of aquifers faster than it is replaced by precipitation.
oxygen demand
The need for molecular oxygen to meet the needs of biological and chemical processes
in water. Even though very little oxygen will dissolve in water, it is extremely
important in biological and chemical processes.
ozone
Molecule made up of three atoms of oxygen (O3). In the stratosphere, it occurs
naturally and it provides a protective layer shielding the Earth from ultraviolet
radiation and subsequent harmful health effects on humans and the environment.
In the troposphere, it is a chemical oxidant and major component of photochemical
smog.
Palmer drought severity index
Depicts prolonged (months, years) of abnormal
dryness or wetness. It responds slowly, changes little from week to week and
reflects long-term moisture, runoff, recharge and deep percolation, as well
as evaporation. pH- A measure of the relative acidity or alkalinity of water.
Water with a pH of 7 is neutral; lower pH levels indicate increasing acidity,
while pH levels higher than 7 indicate increasingly basic solutions. View a
diagram about pH.
particle size
The diameter, in millimeters, of suspended sediment or bed material. Particle-size
classifications are: [1] Clay-0.00024-0.004 millimeters (mm); [2] Silt-0.004-0.062
mm; [3] Sand-0.062-2.0 mm; and [4] Gravel-2.0-64.0 mm.
pathogen
A disease-producing agent; usually applied
to a living organism, any viruses, bacteria or fungi that cause disease.
peak flow
The maximum instantaneous discharge of a stream or river at a given location.
It usually occurs at or near the time of maximum stage.
percolation
(1) the movement of water through the openings in rock or soil, usually continuing
downward to the ground water or water table reservoirs, without a definite channel.
(2) The entrance of a portion of the stream flow into the channel materials
to contribute to ground water replenishment
perched water table
Water table of a relatively small ground water body lying above the general
ground water body.
permeable
Permeability is a measure of the ease with which a fluid will move through a
porous material (e.g., sand and gravel or rock). A geologic unit is permeable
if ground water moves easily through it.
permeability
(1) Ability of a material (generally an earth material) to transmit fluids (water)
through its pores when subjected to pressure or a difference in head. Expressed
in units of volume of fluid (water) per unit time per cross section area of
material for a given hydraulic head; (2) Description of the ease a fluid may
move through a porous medium; abbreviation of intrinsic permeability. The property
of the porous medium only, in contrast to hydraulic conductivity, that is a
property of both the porous medium and the fluid content of the medium.
pluvial
Pertaining to precipitation.
point source pollution
Water pollution resulting from the discharges into receiving waters from easily
identifiable "points." Common point sources of pollution are discharges from
factories and municipal sewage treatment plants.
pollution
(Legal) The alteration of the physical, thermal, chemical or biological quality
or the contamination of any water in the state that renders the water harmful,
detrimental or injurious to humans, animal life, vegetation or property or to
public health, safety or welfare or impairs the usefulness or the public enjoyment
of the water for any lawful or reasonable purpose.
polychlorinated biphenyls (PCBs)
A group of synthetic, toxic industrial chemical compounds once used in making
paint and electrical transformers that are chemically inert and not biodegradable.
PCBs were frequently found in industrial wastes and subsequently found their
way into surface and ground waters. As a result of their persistence, they tend
to accumulate in the environment. In terms of streams and rivers, PCBs are drawn
to sediment to which they attach and can remain almost indefinitely. Although
virtually banned in 1979 with the passage of the Toxic Substances Control Act,
they continue to appear in the flesh of fish and other animals.
poor aquifer
An aquifer which is normally capable of yielding only sufficient water from
wells or springs to supply single houses, small farms or group water schemes.
Often subdivided into: Bedrock aquifers that are generally unproductive except
for local zones (PI) and Bedrock aquifers that are generally unproductive (Pu).
porosity
A measure of the water-bearing capacity of
subsurface rock. With respect to water movement, it is not just the total magnitude
of porosity that is important, but also the size of the voids and the extent
they are interconnected, as the pores in a formation may be open or interconnected
or closed and isolated. For example, clay may have a very high porosity with
respect to potential water content, but it constitutes a poor medium as an aquifer
because the pores are usually so small.
potable water
Water of a quality suitable for drinking.
potential evapotranspiration (PET)
Maximum amount of soil evaporation and transpiration from a well-irrigated crop
for a given set of environmental conditions.
precipitation
Water in some form that falls from the atmosphere. It can be in the form of
liquid (rain or drizzle) or solid (snow, hail, sleet).
primary wastewater treatment
The first stage of the wastewater-treatment process where mechanical methods,
such as filters and scrapers are utilized to remove pollutants. Solid material
in sewage also settles out in this process.
prior appropriation doctrine
System for allocating water to private individuals used in most Western states.
The doctrine of Prior Appropriation was in common use throughout the arid West
as early settlers and miners began to develop the land. The prior appropriation
doctrine is based on the concept of "First in Time, First in Right." The first
person to take a quantity of water and put it to beneficial use has a higher
priority of right than a subsequent user. The rights can be lost through nonuse;
or can be sold or transferred apart from the land: contrasts with riparian water
rights.
public-private partnerships
Facilities still owned by the government, but with private vendors providing
water and wastewater management services under fixed, short-term contracts lasting
3-5 years.
public supply
Water withdrawn by public governments and agencies, such as a county water department
and by private companies then delivered to users. Public suppliers provide water
for domestic, commercial, thermoelectric power, industrial and public water
users. Most household water is delivered by a public water supplier. The systems
have at least 15 service connections (such as households, businesses or schools)
or regularly serve at least 25 individuals daily for at least 60 days out of
the year.
public water use
Water supplied from a public-water supply and used for such purposes as firefighting,
street washing and municipal parks and swimming pools.
privatization
The outright divestiture of both management responsibilities and capital assets
to private companies who agree to provide water and wastewater management services.
radiatively active gases
Gases that absorb incoming solar radiation or outgoing infrared radiation thus
affecting the vertical temperature profile of the atmosphere. Radiatively active
gases are water vapor, CO2, methane, nitrous oxide, chlorofluorocarbons and
ozone.
radioactivity
Release of energy and energetic particles by changes that occur within atomic
or nuclear structures. Radioactive energy is released in various ways such as
alpha radiation, beta radiation and gamma radiation. Radioactivity data is expressed
in terms of concentration of specific nuclides. General measurements of total
or gross alpha or beta and gamma activity also are often reported. The radioactivity
of water is expressed as the rate of radioactive disintegration (curies) per
liter of water.
rating curve
A drawn curve showing the relation between gage height and discharge of a stream
at a given gauging station.
recharge
The replenishment of ground water in an aquifer. It can be either natural, through
the movement of precipitation into an aquifer or artificial-the pumping of water
into an aquifer.
recharge area
A geographic area where water enters (recharges) an aquifer. Recharge areas
usually coincide with topographically elevated regions where aquifer units crop
out at the surface. In these areas infiltrated precipitation is the primary
source of recharge. The recharge area may also coincide with the area of hydraulic
connection where one aquifer receives flow from another adjacent aquifer.
reclaimed wastewater
Treated wastewater utilized for beneficial purposes, such as irrigating certain
plants.
recycled water
Water used more than one time before it passes back into the natural hydrologic
system.
regional flow system
See ground water flow system.
regional water supply problems
Linking more municipal water systems; creating a countywide water system; developing
a public/private utility district selling wholesale water to small towns.
regulated flow
Surface flow downstream from a dam or other flow control structure.
reservoir
A pond, lake, tank or basin, (natural or artificial) where water is collected
and used for the storage, regulation and control of water. Large bodies of ground
water are called ground water reservoirs; water behind a dam is also called
a reservoir of water.
reuse (of water)
Water discharged by one user and used by other users. Sometimes, it also means
water discharged by one unit and used by other units in the same plant. Also
referred to as Recycled Water.
reservoir capacity
Amount of water a surface reservoir is capable of storing.
reservoir storage
(1) Water stored in a surface reservoir returned to its original source or another
body of water. (2) (Irrigation) drainage water from irrigated farmlands that
re-enters the water system to be used further downstream.
resurgence
A speleologic term for spring of the exit of ground water to the surface. Often
refers to the downstream cave opening. An opening where flowing surface water
enters the subsurface is known as an insurgence.
return flow (irrigation)
Irrigation water applied to an area and not consumed in evaporation or transpiration
and returns to a surface stream or aquifer.
reverse osmosis
(1) (Desalination) The process of removing salts from water using a membrane.
With reverse osmosis, the product water passes through a fine membrane the salts
are unable to pass through, while the salt waste (brine) is removed and disposed.
This process differs from electro dialysis, where salts are extracted from the
feed water by using a membrane with an electrical current to separate the ions.
The positive ions go through one membrane, while the negative ions flow through
a different membrane, leaving the end product of freshwater. (2) (Water quality)
an advanced method of water or wastewater treatment that relies on a semi-permeable
membrane to separate waters from pollutants. An external force is used to reverse
the normal osmotic process resulting in the solvent moving from a solution of
higher concentration to one of lower concentration.
riparian
Of or pertaining to rivers and their banks.
riparian habitat
Natural home of plants and animals occurring in a thin strip of land bordering
a stream or river. Dominant vegetation often consists of phreatophytes.
riparian water rights
The rights of an owner whose land abuts water. They differ from state to state
and often depend on whether the water is a river, lake or ocean. The doctrine
of riparian rights is an old one, having its origins in English common law.
Specifically, persons who own land adjacent to a stream have the right to make
reasonable use of the stream. Riparian users of a stream share the stream flow
among themselves and the concept of priority of use (Prior Appropriation Doctrine)
is not applicable. Riparian rights cannot be sold or transferred for use on
nonriparian land.
risk assessment
The qualitative and quantitative evaluation performed in an effort to define
the risk posed to human health and /or the environment by the presence or potential
presence and/or use of specific pollutants.
river
A natural stream of water of considerable volume, larger than a brook or creek.
river basin
A term used to designate the area drained by a river and its tributaries. See
drainage basin.
root zone
Subsurface zone extending from the land surface to the maximum depth penetrated
by roots.
runoff
(1) Part of the precipitation, snow melt or irrigation water that appears in
uncontrolled surface streams, rivers, drains or sewers. Runoff may be classified
according to speed of appearance after rainfall or melting snow as direct runoff
or base runoff and according to source as surface runoff, storm interflow or
ground water runoff. (2) The total discharge described in (1), above, during
a specified period of time. (3) Also defined as the depth to which a drainage
area would be covered if the runoff for a given period of time were uniformly
distributed over it.
rural water use
Term used in previous water-use circulars to describe water used in suburban
or farm areas for domestic and livestock needs. The water generally is self
supplied and includes domestic use, drinking water for livestock and other uses,
such as dairy sanitation, evaporation from stock-watering ponds and cleaning
and waste disposal. See also domestic water use, livestock water use and self-supplies
water.
saline water
Water that contains significant amounts of dissolved solids. Here are our parameters
for saline water: Fresh water - Less than 1,000 parts per million (ppm) Slightly
saline water - From 1,000 ppm to 3,000 ppm Moderately saline water - From 3,000
ppm to 10,000 ppm Highly saline water - From 10,000 ppm to 35,000 ppm SALINITY-
The total quantity of dissolved salts in water, usually measured by weight in
milligrams per liter (mg/L) or parts per million (ppm). The upper limit for
freshwater is 1,000 mg/L; natural seawater has a salinity of approximately 35,000
mg/L.
saltwater intrusion
Movement of saltwater into freshwater aquifers.
sand
A rock fragment or mineral particle smaller than a granule and larger than a
coarse silt grain. Its diameter ranges from 1/16 to 2 mm.
sandstone
Rock formed by the compaction and/or cementing of sand, cement (matrix) material
can be calcite, hematite (FeO2) or other materials.
saturated thickness
The vertical thickness of an aquifer that is full of water, the upper surface
is the water table. The height of the hydrogeologically defined aquifer unit
in which the pore spaces are filled (saturated) with water. For the High Plains
aquifer and similar unconfined, unconsolidated aquifers, the saturated thickness
is equal to the difference in elevation between the bedrock surface and the
water table. The predevelopment saturated thickness is based on the best available
estimate of the elevation of the water table prior to human alteration by ground
water pumping.
saturated zone
That portion of soil or an aquifer in which all of the pore space is filled
with water.
scallop
A speleothem formed from solution by water movement on bedrock surfaces. Abrasion
erosion on rock surfaces form flat surfaces on rock, but solutional erosion
often produces a dimpled surface like that of a golf ball. The steeper side
of the dimple is the upstream side.
secondary standard
The maximum concentration recommended for a substance in water for a particular
use. An example of secondary standard for drinking water is 250 mg/L chloride
that is based mainly on taste.
secondary wastewater treatment
Treatment (following primary wastewater treatment) involving the biological
process of reducing suspended, colloidal and dissolved organic matter in effluent
from primary treatment systems and which generally removes 80 to 95 percent
of the Biochemical Oxygen Demand (BOD) and suspended matter. Secondary wastewater
treatment may be accomplished by biological or chemical-physical methods. Activated
sludge and trickling filters are two of the most common means of secondary treatment,
accomplished by bringing together waste, bacteria and oxygen in trickling filters
or in the activated sludge process. This treatment removes floating and settable
solids and about 90 percent of the oxygen-demanding substances and suspended
solids. Disinfection is the final stage of secondary treatment.
sediment
The layer of soil, sand and minerals at the bottom of surface water-such as
streams, lakes and rivers-that absorb contaminants. Also, particles derived
from rocks, soil or biological material that are transported and deposited by
moving surface water.
sedimentary rock
Rock formed of sediment and specifically: (1) sandstone and shale formed of
fragments of other rock transported from their sources and deposited in water;
and (2) rocks formed by or from secretions of organisms, such as most limestone.
Many sedimentary rocks show distinct layering, the result of different types
of sediment deposited in succession.
sedimentation tanks
Wastewater tanks where floating wastes are skimmed off and settled solids are
removed for disposal.
seepage
(1) The slow movement of water through small cracks, pores, Interstices, etc.,
of a material into or out of a body of surface or subsurface water. (2) The
loss of water by infiltration into the soil from a canal, ditches, laterals,
watercourse, reservoir, storage facilities or other body of water or from a
field.
self-supplied water
Water withdrawn from a surface-or ground water source by a user rather than
obtained from a public supply. An example would be homeowners getting their
water from their own well.
septic tank
A tank used to detain domestic wastes to allow the settling of solids prior
to distribution to a leach field for soil absorption. Septic tanks are used
when a sewer line is not available to carry them to a treatment plant. A settling
tank in which settled sludge is in immediate contact with sewage flowing through
the tank and wherein solids decompose by anaerobic bacterial action.
settling pond (water quality)
An open lagoon where wastewater contaminated with solid pollutants is placed
and allowed to stand. The solid pollutants suspended in the water sink to the
bottom of the lagoon and the liquid is allowed to overflow out of the enclosure.
sewage treatment plant
A facility designed to receive the wastewater from domestic sources and to remove
materials that damage water quality and threaten public health and safety when
discharged into receiving streams or bodies of water. The substances removed
are classified into four basic areas: [1] greases and fats; [2] solids from
human waste and other sources; [3] dissolved pollutants from human waste and
decomposition products; and [4] dangerous microorganisms. Most facilities employ
a combination of mechanical removal steps and bacterial decomposition to achieve
the desired results. Chlorine is often added to discharges from the plants to
reduce the danger of spreading disease by the release of pathogenic bacteria.
sewer
A system of underground pipes that collect and deliver wastewater to treatment
facilities or streams.
simulation
In ground water-flow modeling, one complete execution of a ground water-modeling
computer program, including input and output.
sink (sinkhole)
A depression in the surface of the earth caused by solution and/or collapse
of rock. A sink is an entry point for water into cave and spring systems. All
sinks will carry water into the subsurface.
sludge
Precipitated solid matter produced by water and sewage or mineral treatment
processes.
soil horizon
Layer of soil or soil material approximately parallel to the land surface and
differing from adjacent genetically related layers in physical, chemical and
biological properties or characteristics such as color, structure, texture,
consistency, kinds and number of organisms present, degree of acidity or alkalinity,
etc.
soil moisture
Water in the root zone.
soil-water potential
Energy with which water is held in a soil at any water content. It is the potential
energy per unit quantity (unit mass, unit weight or unit volume) of water in
a system, compared to that of pure (no solutes); free water (no external forces
other than gravity) at the same location (which represents the reference state
of zero value). Potential energy is the energy of the water potentially available
to be released when the water moves from one position to another. Because water
is held in the soil by forces of adsorption, cohesion and solution, soil water
is not usually capable of doing as much work as pure free water; hence, the
soil-water potential is normally negative. The soil-water potential can be considered
as the sum of component potentials, such as matric or capillary potential (resulting
from the capillary and adsorptive forces due to the soil matrix), gravitational
potential (resulting from relative elevation differences) and osmotic potential
(resulting from the presence of solutes; it comes into play whenever a membrane
or diffusion barrier is present that transmits water more readily than salts
or solutes) and others. A soil-water potential gradient (which is the change
of energy potential with distance) is required to cause fluid to flow. For some
applications, certain combinations of component potentials are used so often
that for ease of referring to them it is desirable to give the combination a
name. For liquid water flow in soils, it is convenient to combine component
potentials that serve as driving forces-pressure, matric and gravitational potentials
and call the combination by the name of hydraulic potential. If the unit quantity
is measured as weight, then the units of hydraulic potential are energy per
unit weight, which are exactly equal to the units of hydraulic head.
solute
A substance dissolved in another substance, thus forming a solution.
solution
Geologically, the action of the dissolving of rock by water, or the term to
describe the water, that dissolves the rock. Limestone dissolves in acidic solutions;
gypsum can be dissolved in pure water. On dissolving the rock, the water becomes
a calcite solution (the calcite may later be re-deposited).
solvent
A substance that dissolves other substances and forms a solution. Water dissolves
more substances than any other and is known as the "universal solvent".
speleothem
A deposit formed in caves when calcium carbonate (CaCO3) or some other mineral
precipitates from drips or thin films of water. Stalactites and stalagmites
are common speleothems.
specific conductance
A measure of the ability of water to conduct an electrical current as measured
using a 1-cm cell and expressed in units of electrical conductance, i.e., Siemens
per centimeter at 25 degrees Celsius. Specific conductance can be used for approximating
the total dissolved solids content of water by testing its capacity to carry
an electrical current. In water quality, specific conductance is used in ground
water monitoring as an indication of the presence of ions of chemical substances
that may have been released by a leaking landfill or other waste storage or
disposal facility. A higher specific conductance in water drawn from downgradient
wells when compared to upgradient wells indicates possible contamination from
the facility.
specific discharge
For ground water, the rate of discharge of ground water per unit area measured
at right angles to the direction of flow.
specific retention
Ratio of the volume of water a given body of rock or soil will hold against
the pull of gravity to the volume of the body itself. It is usually expressed
as a percentage. Compare with field capacity.
specific storage
Volume of water released from or taken into storage per unit volume of the porous
medium per unit change in head. It is the three-dimensional equivalent of storage
coefficient or storativity and is equal to storativity divided by aquifer saturated
thickness.
specific yield
The quantity of water given up by a unit volume of a substance when drained
by gravity.
spillway
The channel or passageway around or over a dam through which excess water is
diverted.
spray irrigation
A common irrigation method where water is shot from high-pressure sprayers onto
crops. Because water is shot high into the air onto crops, some water is lost
to evaporation.
spring
A place where ground water flows naturally from the earth into a body of surface
water or onto the land surface, at a rate sufficient to form a current.
steady-state flow
A flow system's characteristics where the magnitude and direction of specific
discharge are constant in time at any point.
storm sewer
A sewer that carries only surface runoff, street wash and snow melt from the
land. In a separate sewer system, storm sewers are completely separate from
those that carry domestic and commercial wastewater (sanitary sewers).
stream
A general term for a body of flowing water; natural water course containing
water at least part of the year. In hydrology, it is generally applied to the
water flowing in a natural channel as distinct from a canal.
stream hydrograph
See hydrograph.
stream reach
Specific portion of the length of a stream.
streamflow
The discharge that occurs in a natural channel. Although the term discharge
can be applied to the flow of a canal, the work streamflow uniquely describes
the discharge in a surface stream course. The term "streamflow" is more general
than runoff, as streamflow may be applied to discharge whether or not it is
affected by diversion or regulation.
strong sustainability
View that, given the limits to substitution between some natural capital and
other economic assets (such as reproducible or human-made capital), as well
as the problems of irreversibility, uncertainty of threshold effects and the
potential scale of social costs associated with loss of certain environmental
assets, sustainable development cannot be assured without imposing some conditions
on the depletion of natural capital. For example, if some minimum level of biodiversity
is essential for ecosystem functioning and resilience, preserving the economic
opportunities available to future generations requires the prevention of biodiversity
loss that threatens this minimum threshold level.
sublimation
Transition of water directly from the solid state to the gaseous state, without
passing through the liquid state or vice versa.
subsidence
A dropping of the land surface as a result of ground water being pumped. Cracks
and fissures can appear in the land. Subsidence is virtually an irreversible
process.
substrate
1) That which is laid or spread under; an underlying layer, such as the subsoil;
(2) The substance, base or nutrient on which an organism grows; (3) Compounds
or substances acted upon by enzymes or catalysts and changed to other compounds
in the chemical reaction.
subsurface
Underground, below the earth's surface.
subsurface water
All water below the land surface, including soil moisture, capillary fringe
water in the vadose zone and ground water.
sulfate
The anionic constituent SO4 that has two negative charges as dissolved in water.
summer fallow
Special case of fallowing in which all vegetative growth is prevented by shallow
tillage in conjunction with or without herbicides during the summer months,
in place of growing a crop in order to store water for use by the next crop.
surface tension
The attraction of molecules to each other on a liquid's surface, a barrier is
created between the air and the liquid.
surface water
Water on the Earth's surface exposed to the atmosphere, e.g., rivers, lakes,
streams, oceans, ponds, reservoirs, etc.
suspended
Sediment concentration, the ratio of the mass of dry sediment in a water-sediment
mixture to the mass of the water-sediment mixture. Typically expressed in milligrams
of dry sediment per liter of water-sediment mixture.
suspended sediment
Very fine soil particles that remain in suspension in water for a considerable
period of time without contact with the bottom. Such material remains in suspension
due to the upward components of turbulence and currents and/or by suspension.
suspended sediment discharge
The quantity of suspended sediment passing a point in a stream over a specified
period of time. When expressed in tons per day, it is computed by multiplying
water discharge (in cubic feet per second) by the suspended-sediment concentration
(in milligrams per liter) and by the factor 0.0027.
suspended solids
Solids not in a true solution and that can be removed by filtration. Such suspended
solids usually contribute directly to turbidity. Defined in waste management,
these are small particles of solid pollutants that resist separation by conventional
methods.
sustainable development
Economic and social development that increases the welfare of current generations
without affecting adversely the welfare of future generations. For example,
future generations have economic opportunities that are at least as large as
earlier generations. See strong sustainability and weak sustainability. Sustainable
development by its very nature is a multidimensional concept. This concept involves
not only the management and conservation of the natural resource-base, but also
the social, institutional, technological and cultural changes involved. Though
it is extremely difficult to conceptualize ideally what sustainable development
means, definition of sustainable development has to be sufficiently broad to
be able to capture the various dimensions involved. See also environmental sustainability.
tertiary wastewater treatment
Selected biological, physical and chemical separation processes to remove organic
and inorganic substances resistant to conventional treatment practices; the
additional treatment of effluent beyond that of primary and secondary treatment
methods to obtain a very high quality of effluent. The complete wastewater treatment
process typically involves a three-phase process: (1) in the primary wastewater
treatment process, which incorporates physical aspects, untreated water is passed
through a series of screens to remove solid wastes; (2) the secondary wastewater
treatment process, typically involving biological and chemical processes, screened
wastewater is then passed a series of holding and aeration tanks and ponds;
and (3) the tertiary wastewater treatment process consists of flocculation basins,
clarifiers, filters and chlorine basins or ozone or ultraviolet radiation processes.
thermal pollution
A reduction in water quality caused by increasing its temperature, often due
to disposal of waste heat from industrial or power generation processes. Thermally
polluted water often undergoes biological changes that render it less valuable
for drinking, recreation, habitat or industrial use. Thermally polluted water
can harm the environment because plants and animals can have a hard time adapting
to it.
thermoelectric power water use
Water used in the process of the generation of thermoelectric power. Power plants
that burn coal and oil are examples of thermoelectric-power facilities.
thermohaline
Refers to the combined effects of temperature and salinity that contribute to
density variations in the oceans.
topographic map
A map that shows natural human-made features of an area using contour lines
(lines of equal elevation) to portray the size, shape and elevation of the features.
topography
Physical features, such as hills, valleys and plains that shape the surface
of the Earth.
toxicity
The occurrence of lethal or sub-lethal adverse effects on organisms due to exposure
to toxic materials. Adverse effects caused by conditions of temperature, dissolved
oxygen or nontoxic dissolved substances are excluded from the definition of
toxicity.
trace gas
Minor constituent of the atmosphere. The most important trace gases contributing
to the greenhouse effect are water vapor, carbon dioxide, ozone, methane, ammonia,
nitric acid, nitrous oxide, ethylene, sulfur dioxide, nitric oxide, dichloro-fluoromethane
or Freon 12, trichlorofluoromethane or Freon 11, methyl chloride, carbon monoxide
and carbon tetrachloride.
"tragedy of the commons"
The idea that no one takes responsibility for things that everybody owns, generally
associated with Garrett Hardin.
transfer
The withdrawal, diversion or pumping of surface water from one river basin and
discharge of all or any part of the water in a river basin different from the
origin.
transition curve
or growth curve
or response curve
Graph indicating the fraction of ground water pumping derived from ground water
storage or a surface-water source plotted against time.
transmissibility (ground water)
The capacity of a rock to transmit water under pressure. The coefficient of
transmissibility is the rate of flow of water, at the prevailing water temperature,
in gallons per day, through a vertical strip of the aquifer one foot wide, extending
the full-saturated height of the aquifer under a hydraulic gradient of 100-percent.
A hydraulic gradient of 100-percent means a one foot drop in head in one foot
of flow distance.
transmissivity
Flow capacity of an aquifer measured in volume per unit time per unit width.
Equal to the product of hydraulic conductivity times the saturated thickness
of the aquifer.
transpiration
Process by which water vapor escapes from living plants, principally from the
leaves and enters the atmosphere.
travertine
A finely crystalline limestone deposited by ground water and surface water.
tributary
A stream or other body of water, surface or underground, that contributes its
water, even if intermittently and in small quantities, to another and larger
stream or body of water. Usually, a number of smaller tributaries merge to form
a river.
turbidity
The amount of solid particles suspended in water and that cause light rays shining
through the water to scatter. Thus, turbidity makes the water cloudy or even
opaque in extreme cases. Turbidity is measured in nephelometric turbidity units
(NTU).
troposphere
The layer of atmosphere closest to the earth,
extending seven to ten miles above the earth, it usually contains clouds and
moisture.
ULTRAVIOLET (UV) RADIATION
Type of short-wave radiation
damaging to plants and animals, including humans. The amount of UV radiation
that reaches the earth depends on the amount of stratospheric ozone. An increase
in UV radiation due to a decrease in stratospheric ozone will pose a direct
threat to human health (increased cataracts, immune suppressions and skin cancers)
and will have a negative impact on plant yields for many species.
UNCED
United Nations Conference on Environment and Development held in Rio de Janeiro,
June, 1992; also referred to as the Earth Summit.
unconfined aquifer
An aquifer where the water table is exposed to the atmosphere through openings
in the overlying material.
underflow
(1) Ground water flow within a streambed below a surface stream; (2) Lateral
movement of water through the soil zone, also known as interflow.
unsaturated zone
Zone immediately below the land surface where the pores contain both water and
air, but are not totally saturated with water. These zones differ from an aquifer,
where the pores are saturated with water, also known as the vadose zone.
upconing
The upward movement of ground water from a deeper to shallower position in the
aquifer, usually induced by pumping a well or discharge to the surface.
upgradient
In reference to the movement of ground water, the "upstream" direction from
a point of reference (e.g., a well).
uplift
An upheaval; elevation or rising of part of the earth's surface through forces
within the earth.
upstream
Toward the source or upper part of a stream, against the current. In relation
to water rights, the term refers to water uses or locations that affect water
quality or quantity of downstream water uses or locations.
U.S. EPA
United States Environmental Protection Agency.
USGS
United States Geological Survey.
vadose
Indicates the area below the earth surface but above the water table, includes
all ground water above the water table. In caves, vadose water forms stalactites
and other dripstone speleothems. Vadose cave streams carve trenches and canyons
and vertical pits as the water table lowers with time.
vadose zone
Unsaturated (not completely filled with water) zone lying between the earth's
surface and the top of the ground water. Also known as unsaturated zone and
zone of aeration.
vested water right
Right granted by a state water agency to use either surface or ground water.
wadi
Steep-sided valley, rocky ravine, riverbed or gully usually dry in a semi-desert
or desert area of the Sahara and the Arab countries of southwest Asia.
waldsterben
German word meaning forest death and used to describe the rapid decline and
death of large areas of trees. It is thought to be a result of ozone pollution
that damages the leaves of trees, resulting in stunted growth and an inability
to regenerate. More than half of Germany's forests are affected, as well as
extensive areas in most other European and Scandinavian countries. The main
cause is considered to be pollution from vehicle exhausts.
wastewater
Water used in homes, industries and businesses not for reuse unless it is treated.
wastewater treatment
Processing of wastewater by treatment facilities for the removal or reduction
of contained solids or other undesirable constituents. Often chlorine is added
to wastewater before it is returned to a source (river, etc.).
water balance
A mathematical construction that shows the amount of water leaving and entering
a given watershed or aquifer.
water cycle
The circuit of water movement from the oceans to the atmosphere and to the Earth
and return to the atmosphere through various stages or processes such as precipitation,
interception, runoff, infiltration, percolation, storage, evaporation and transportation.
water flux
A volume of water per unit area per time.
water potential
See soil-water potential.
water quality
A term used to describe the chemical, physical and biological characteristics
of water, usually in respect to its suitability for a particular purpose.
water right
Any vested or appropriation right under which a person may lawfully divert and
use water. It is a real property right appurtenant to and severable from the
land on or in connection with which the water is used; such water right passes
as an appurtenance with a conveyance of the land by deed, lease, mortgage, will
or inheritance.
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. Large watersheds, like the Mississippi
River basin contain thousands of smaller watersheds.
water table
A fluctuating demarcation line between the unsaturated (vadose) zone and the
saturated (phreatic) zone that forms an aquifer. It may rise or fall depending
on precipitation (rainfall) trends. The water table is semi-parallel to the
land surface above but is not always a consistent straight line. Because of
impervious beds of shale, etc., local water tables can be perched above the
area's average water table.
water transfer
Legal change in a water right reflecting some combination of a change in ownership
of diversion, place of use and/or type of use to another.
water use
Water used for a specific purpose, such as for domestic use, irrigation or industrial
processing. Water use pertains to human's interaction with and influence on
the hydrologic cycle and includes elements, such as water withdrawal from surface-
and ground water sources, water delivery to homes and businesses, consumptive
use of water, water released from wastewater-treatment plants, water returned
to the environment and in-stream uses, such as using water to produce hydroelectric
power.
water use efficiency (WUE)
Ratio of crop biomass accumulation or yield to the amount of water used in evapotranspiration.
water vapor
Water present in the atmosphere in gaseous
form, the source of all forms of condensation and precipitation. Water vapor,
clouds and carbon dioxide are the main atmospheric components in the exchange
of terrestrial radiation in the troposphere serving as a regulator of planetary
temperatures via the greenhouse effect. Approximately 50 percent of the atmosphere's
moisture lies within about 1.84 km of the earth's surface and only a minute
fraction of the total occurs above the tropopause.
water vapor feedback
Process in which an increase in the amount of water vapor increased the atmosphere's
absorption of long-wave radiation, thereby contributing to a warming of the
atmosphere. Warming, in turn, may result in increased evaporation and an increase
in the initial water vapor anomaly. This feedback, along with carbon dioxide,
is responsible for the greenhouse effect and operates virtually continuously
in the atmosphere.
water year
12-month period of which the U.S. Geological Survey reports surface-water supplies.
Water years begin October 1 and end the following September 30 and are designated
by the calendar year in which the water year ends.
watt hour (WH)
An electrical energy unit of measure equal to one watt of power supplied to
or taken from, an electrical circuit steadily for one hour.
WCED (World
Commision on Environment and Development)
United Nations Commission, also known as the Brundtland Commission, which garnered
almost worldwide political consensus on the urgent need for sustainability;
its findings are published in the widely acclaimed report "Our Common Future"
(1987).
weak sustainability
View that sustainable development can be assured through the conservation of
aggregate capital alone. Although natural capital is being depleted, it is being
replaced with even more valuable human-made capital and thus the value of the
aggregate stock-comprising both human-made and the remaining natural capital-is
increasing over time in terms of its ability to maintain or enhance human welfare.
weather generator (stochastic)
Program that generates weather values for daily precipitation, temperatures
and solar radiation based on observed historical patterns.
weather modificaiton
Deliberate modification of weather to increase precipitation and water supplies.
Cloud seeding is the most common method of weather modification.
well (water)
An artificial excavation put down by any method for the purposes of withdrawing
water from the underground aquifers. A bored, drilled, driven shaft or a dug
hole whose depth is greater than the largest surface dimension and whose purpose
is to reach underground water supplies or oil or to store or bury fluids below
ground.
well screen
A slotted section of pipe usually placed in the borehole adjacent to the main
aquifer unit or units that supplies the well with water.
well yield
Maximum pumping rate supplied by a well, without drawing the water level in
the well below the pump intake. See yield.
wetlands
An area (including swamp, marsh, bog, prairie pothole or similar area) tending
to be inundated or saturated by surface or ground water at a frequency and duration
sufficient to support the growth and regeneration of hydrophytic vegetation
(plants growing in water, at least periodically, deficient in oxygen during
a growing season as a result of excessive water content). The term "wetland"
does not include irrigated acreage used as farmland; a man-made wetland of less
than one acre; or a man-made wetland not constructed with wetland creation as
a stated objective, including but not limited to an impoundment made for the
purpose of soil and water conservation which has been approved or requested
by soil and water conservation districts.
withdrawal
Water removed from a ground- or surface-water source for use.
xeriscaping
A method of landscaping that uses plants that are well adapted to the local
area and are drought-resistant. Xeriscaping is becoming more popular as a way
of saving water at home.
yield
Amount of water that can be supplied from a reservoir, aquifer, basin or other
system during a specified interval of time. This time period may vary from a
day to several years depending upon the size of the system involved.
Sources
http://www.kgs.ukans.edu/HighPlains/atlas/glossary.htm
http://ga.water.usgs.gov/edu/dictionary.html
http://www.worldatlas.com/h2oterms.htm
http://www.waterinfo.org/terms.html
http://www.briodydrilling.com/aquifer.html