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Groundwater

Groundwater. Ground water does not occur as an underground ______ UNLESS it is found in a cave. Most groundwater occurs in small ________________ within rock and unconsolidated sediment Water flows through this sediment __________…. A few centimeters to meters per _______.

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Groundwater

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  1. Groundwater Ground water does not occur as an underground ______ UNLESS it is found in a cave.

  2. Most groundwater occurs in small ________________ within rock and unconsolidated sediment Water flows through this sediment __________…. A few centimeters to meters per _______. Groundwater tends to collect above materials that are ______________. So where is groundwater stored and what does it look like?

  3. Porosity ___________ The amount of space in between sediment grains, cracks or fractures in rocks. These spaces may be filled with _____, air or a mixture of both. What kind of material has the highest porosity? Sediment Porosity % Gravel 25 to 40 _________ 30 to 50 Silt 35 to 50 __________ 35 to 80 Glacial Till 10 to 20 More about Porosity

  4. Permeability This is the ability to ___________ water. Rocks may have high porosity, but if the spaces or pores are _________________, then the permeability will be very _____. Materials that can transmit large quantities of water beneath the surface are called ___________.

  5. Recall what types of material have the highest ____________. Sediment Porosity (%) • Gravel 25 to 40 • Clean Sand 30 to 50 • Silt 35 to 50 • Clay 35 to 80 • Glacial Till 10 to 20 What kind of materials have a high permeability?

  6. Distribution of Water

  7. Distribution of Groundwater • Unsaturated Zone – Region that covers the ground surface down to the ___________________. This area may have pore spaces that are partially filled with _____________. The unfilled pore space contains air.

  8. Saturated Zone – Region of the subsurface where the pore spaces are completely filled with water.______________ – Area where the unsaturated and saturated zones meet in unconfined aquifers. (Very top of the saturated zone)_______________ – Area above the water table where capillary forces pull water into pore spaces.

  9. What is the difference between these to aquifers? Hint: Compare their layers Bedrock Bedrock Clay Bedrock

  10. Confined Aquifer- Aquifer is between 2 layers of ___________ matter. Water is pressurized Wells are called ____________ wells Unconfined Aquifer- Water is not confined on the top and bottom of saturated zone. Water can freely move to the surface if the water table rises. The level of the water in a well will be the _____________ as ground water level.

  11. Describe the difference of water flow with respect to the streams and the water table in the diagrams below

  12. Confined groundwater may flow at the surface due to hydrostatic pressure.

  13. ______________Water flows freely from the ground surface.This happens when the water table intersects the ground surface.

  14. Perched Aquifer

  15. Observe a geyser animation along with an explanation of how a geyser occurs by clicking on Beehive geyser above.

  16. Wells We use wells to remove groundwater. The water table goes down when water is pumped from a well. This is called a cone of depression.

  17. Artesian – Groundwater that is under ___________ rises above the level of the aquifer. • One end of the ___________ aquifer, must be able to receive water • There must be ___________ above and below the aquifer. • If the water does not rise to surface level we call this artesian well a • _______________ artesian well. • When a well is drilled into the aquifer and water rises to surface level or higher, then we have a ___________ artesian well.

  18. Over-pumping can be a real problem in areas of slow recharge. When the groundwater is not recharged at the same rate or faster than groundwater is removed, the water table is ________, wells dry up, and there is an overall depletion of groundwater. Non-renewable resource in some areas – Can be referred to as groundwater mining. In the US there is a huge problem with over pumping in the Southwest and Southern California.

  19. Subsidence When groundwater is over pumped, there is no longer the pressure of water between the pore spaces of unconsolidated material. The overlying material puts lots of weight on this material causing the grains to pack tightly together and the surface to collapse. Click on the picture to link to more information

  20. Sink Holes • http://ga.water.usgs.gov/edu/sinkholes.html

  21. Florida Sinkhole

  22. Cave

  23. Cave

  24. To see an animation of how a cave is formed, click on the image below

  25. What are each of these features? B A C D

  26. These are soda straws

  27. What are each of these features? B A C D

  28. B - Stalactites

  29. What are each of these features? B A C D

  30. C - Stalagmites

  31. What are each of these features? B A C D

  32. D - Column

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