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MOVEMENT AND STORAGE OF GROUND WATER
Hydrosphere - the water on the earth’s crust.
Hydros (Greek word meaning water) 97% of
hydrosphere is in the ocean, 3% of hydrosphere is
fresh water, 90% of the 3% of freshwater is in the
form of polar ice caps and glaciers. 10%
freshwater is in the ground water. Ultimate source
of all water on land is in the ocean. Water in the
atmosphere is from the process of evaporation.
Condensation brings the water back by precipitation.
Water enters the ground through infiltration.
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HYDROSHPERE
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GROUND WATER STORAGE
Porosity = % of pore space in a material. Sub
surface materials have porosities ranging from
2% to 3% or more than 50%.
Sand porosity is 30% . Cement – made with
sand reduces the porosity by binding with the
grains.
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ZONE OF SATURATION AND WATER TABLE
Zone of Saturation - Depth below the earths
surface at which ground water completely fills all
of the pores of the material
Water table - upper boundary of the zone of
saturation, water
table is the water that is located in the zone of
saturation. Zone of aeration - pores in soil that
contain mostly air.
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ZONE OF SATURATION/WATER TABLE
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DROUGHTS
During a drought, the water table is
lower. Water table is dependent on
precipitation, it fluctuates with the
season.
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WATER TABLE- DROUGHT
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SEASONAL CHANGES OF THE WATER TABLE
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WATER
Water in the zone of saturation
can be classified in 2 ways:
1)Gravitational water
2)Capillary water
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WATER CLASSIFICATION
Gravitational water - water that trickles downward as a result
of gravity.
Capillary water - water that is drawn upward from the water
table and is held in the pore spaces of rocks and sediments
as a result of surface tension.
Water table depth depends on local conditions
Stream Valley - few meters deep
Swamp - water almost at the surface
Arid regions - 10’s to 100’s of meters deep
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TOPOGRAPHY
The topography of the water table follows the
land topography. Why?
Underground water moves slowly and conforms
to the surface contours to the surface
contours.
Ground water movement is slow due to
squeezing between the pores in the
subsurface material.
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PERMEABILITY :
The ability of a material to let water pass
through.
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POROSITY OF GROUND MATERIAL
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GROUNDWATER EROSION AND
DEPOSITION
The process by which carbonic acid forms and dissolves calcium carbonate
can be described by the following three equations:
1) Rain falls from the sky and combines with carbon dioxide
H2O
+
CO2
(water)
H2CO3
(carbon dioxide)
(carbonic acid)
2) Carbonic acid molecules in the water split into hydrogen ions and
bicarbonate ions
H2CO3
H
(carbonic acid)
+
(hydrogen ion)
HCO3
(bicarbonate ion)
3) Hydrogen ions react with calcium carbonate and dissolve it
CaCO3
+
H
Ca
+
HCO3 -
(calcium carbonate) (hydrogen ion) (calcium)
(bicarbonate)
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FORMATION OF LIMESTONE CAVES
HCO3 is flushed away into the ground water.
Precipitation of calcium carbonate occurs when
the groundwater evaporates when the gas
carbon dioxide diffuses out of the water.
Both the dissolution and formation of calcium
carbonate play a major role in the formation of
limestone caves.
Cave - a natural underground opening with a
connection to Earth’s surface
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CAVES
A natural underground opening with a connection to the
Earth’s surface.
Ex. Carlbad Caverns -New Mexico
Lechugilla Cave - New Mexico
Mammoth Cave - Kentucky
Caves form when ground water dissolved limestone that
developed in the zone of saturation
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CARLSBAD CAVERNS – NEW MEXICO
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LECHUGUILLA FIFTH LARGEST CAVE- NEW
MEXICO
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CAVE DIVER = LECHUGUILLA CAVE
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CRYSTAL FORMATION AND CAVE DIVER
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NARROW PASSAGES
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MAMMOTH CAVE LARGEST IN THE WORLD
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MAMMOTH CAVE MAP
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ENTRANCE TO MAMMOTH CAVE
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MAMMOTH
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LIMESTONE CAVES
HCO3 is flushed away into the ground water.
Precipitation of calcium carbonate occurs when
the groundwater evaporates when the gas
carbon dioxide diffuses out of the water.
Both the dissolution and formation of calcium
carbonate play a major role in the formation of
limestone caves.
Cave - a natural underground opening with a
connection to Earth’s surface
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CHARACTERISTICS OF DISSOLUTION OF
LIMESTONE
sinkholes - depression in the ground caused by
the collapse of a cave or by the direct dissolution
of bedrock by acidic rain or moist soil.
Another type of feature forms when a surface
stream drains into a cave system, continues
underground, and leaves a dry valley above.
Such a stream, called a sinking stream,
sometimes reemerges abruptly on Earth’s
surface as a karst spring.
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SINK HOLE
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KARST SPRING - CHINA
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SINK HOLE IN FLORIDA
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SINK HOLE IN FLORIDA
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SINKHOLE - GUANTEMALA
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HARD WATER
Hard water contains high concentrations of calcium,
magnesium, or iron. Deposits of calcium carbonate
eventually clog water pipes.
Household use of hard water usually can cause a problem:
deposits of calcium bicarbonate eventually clog water
pipes.
These problems can be controlled with a water softener,
which removes dissolved ions from hard water. Water that
contains few dissolved ions is called soft water
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HARD WATER DEPOSITS IN PIPES
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HARD WATER DEPOSITS ON WINDOWS
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DEPOSITS ON BRICKS
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HARD WATER DEPOSIT IN A TOLIET
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GROUND WATER SYSTEMS
Springs - Natural discharge of groundwater at Earth’s surface
where an aquifer and an aquiclude come in contact.
Ground water system - Hot springs - water with temperature
higher than 98°F, (or hotter than the human body)
because the
substance is still quite hot from recent igneous activity Western U.S.
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AQUICLUDES
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HOT SPRINGS
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GEOTHERMAL POOL
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GEYSERS
Geysers - located near volcanic regions are
explosive hot springs that erupt at regular
intervals - Yellowstone National Park - “Old
Faithful” geyser empties every 1 hour and 40
minutes - shoots up in a high column
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BLACK ROCK GEYSER - NEVADA
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BEEHIVE GEYSERS
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CONE GEYSER
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WELLS
Wells - are holes dug or drilled deep into the
ground to reach a reservoir of groundwater. To
produce water, a well must tap into an
aquifer. The simplest wells are those that are
dug or drilled
below the water table, into the zone of
saturation, and into what is called a water
table aquifer.
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TYPE OF WELLS
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RECHARGE AREA
Recharge - water is added back to
the zone of saturation by
precipitation.
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RECHARGE
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ARTESIAN WELL
Artesian well - Confined aquifer that contains water
under pressure.
The area of recharge is usually higher in elevation then
the rest of the aquifer.
Ex. Ogallala Aquifer located in the United State in the
Great Plains. This aquifer delivers water to a huge
area stretching from South Dakota to Texas.
The recharge areas of the Ogallala Aquifer are located in
the Black Hills and the Rocky Mountains.
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THREATS TO OUR WATER SUPPLY
Overuse
Subsidence (the sinking of land)
Pollution (sewage, industrial waste, landfills and agricultural
chemicals)
Chemicals
Salt
Radon (leading cause of cancer generated by the breakdown
of uranium, the
EPA (Environmental Protection Agency) monitors this
Freshwater is Earth’s most precious natural resource
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