Ground Water

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Ground Water
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Ground Water...An underground lake
Ground Water is water that is located within the
rocks below the Earths surface.

• Zone of Aeration
• Water easily passes through the uppermost zone
• As water percolates, contaminants and particles
  are filtered out of the water

• Zone of Saturation
• Water collects between the spaces of rock
  particles and creates an underground lake

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Locate the Zone of Aeration and Zone of
Saturation. Compare these zones.
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What lies between

• The water table is the boundary between the zone
  of aeration and saturation
• The water table varies in depth from a few
  centimeters below the soil surface to hundreds of
  meters below the Earths surface
• Water table rises during wet seasons
• Water table falls during dry seasons

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The water cycle revisited
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Exactly what is an Aquifer?

• An Aquifer is a rock layer in which ground water
  can freely flow
• Characteristics of an Aquifer
• Porosity (pores or spaces)- the more space
  between particles of an aquifer the more water it
  can hold
• - Larger particles more porous
• - smaller particles less porous

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Additional Characteristics

• Permeability (permeate)- the ability of a rock
  layer to let water pass through
• Larger particles less surface area and less
  friction therefore more permeable
• Smaller particles more surface area and more
  friction therefore less permeable

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Best of the Best!

• The best aquifers form in permeable materials
  such as sandstone, limestone, or layers of sand
  and gravel.
• An aquifer depends on the water cycle to
  continuously recharge itself.
• Water enters an aquifer through a surface
  recharge zone
• The surface recharge zone is permeable for water
  to percolate through easily.

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Springs and Wells

• Springs
• When the water table reaches the Earths surface,
  a spring forms
• If the table is higher than the Earths surface,
  a lake is created
• Springs are important sources of drinking water

• Artesian Springs
• Unlike a regular spring, an artesian formation
  occurs when an aquifer is sandwiched between 2
  layers of impenetrable rock.
• An artesian spring occurs in a crack of the cap
  rock

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Wells

• A human made hole that is deeper than the level
  of the water table is called a well.
• Can dry up if the water table drops below the
  well
• Additionally, can be depleted if too many wells
  access the aquifer and water is removed too
  quickly

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