What is the Water Table?

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AIM How do people use water in the ground? Do
Now Looking at the 3 jars below (filled with the
same amount of sorted beads), describe the
Permeability, Porosity and Capillarity of each.
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I. Water Table
- Marks the location of water underground
(boundary). - rises with precipitation and
lowers with evaporation and usage.

• Zone of Aeration
• Pore space contains mostly air.
• Zone of Saturation
• Pore space contains mostly water.

What must exist below the zone of saturation for
water to fill in the spaces?
Impermeable Rock
3

• A. Groundwater is the zone of saturation.
• - water sheds (drainage basin) are the areas of
  land where water infiltrates to create the
  groundwater supply.
• - ground water can fill lakes, swamps and rivers
  when there is little precipitation.

Is the amount of ground water constant? Give an
example of something that might change the amount
of ground water?
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• B. Aquifer permeable soil/rock that allows
  groundwater to move freely.
• This is filled by the water shed area.

Impermeable rock
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II. Groundwater Features

• A. Springs areas where the water table rises
  and meets the surface naturally.

- Hot Springs Water is heated by magma
underground.
Yellowstone National Park, Wyoming
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• B. Geysers pressurized heated water that is
  forced out of the ground.

What do you think supplies the heat?
- Heat comes from magma
Old Faithful, Yellowstone National Park, Wyoming
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• C. Wells - holes dug below the water table so
  people can access water.

• Pumping causes a drawdown (lowering) of the water
  table.

- this forms a cone of depression in the water
table.
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III. Groundwater Problems

• 1) Overuse and contamination threatens
  groundwater supplies.

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• 2) Sinkholes - surface depressions.
• - over use of the ground water causes subsidence
  (sinking)
• - bedrock dissolves (limestone) and the ground
  collapses.

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Closure

• With the person sitting next you, explain what
  would happen to the water table and ground water
  supply if there were many wells dug into the
  ground in one area?
• Describe what might make the water table move up
  or down within the ground?

Review Book p.128-130 1-10