This Week (and next)

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This Week (and next)

• Today
• Finish Floods
• Groundwater
• Friday Glaciers

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Finally, a flood of possibly mythic proportions

• Noahs Flood hypothesis
• William Ryan Walter Pittman (Columbia U.)
• Controversial, not universally accepted, but
  intriguing

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Noahs Flood

• Coming out of last ice age 7600 years ago (5600
  B.C.), sea level was low but rising
• Why?
• Black Sea was freshwater, surrounded by farms

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Noahs Flood

• Rising global sea level raised Mediterranean
  above the Bosporus Strait
• Broke through natural dam
• Water rose 6 inches / day
• Flooded lakeshore communities

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some Noahs Flood evidence

• Many cultures have a flood story, many can be
  traced to the Black Sea area
• Remains of houses villages have been found on
  the pre-flood lakeshore
• But New work finds no evidence for a sudden
  rise in water level of Black Sea.

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Noahs Flood

• More info
• book Noahs Flood The new scientific
  discoveries about the event that changed
  history, Ryan Pittman, 1998, Simon Schuster

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Todays Plan Groundwater

• aquifer / aquitard
• water table
• groundwater flow
• groundwater contamination

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Groundwater aquifers

• Any geologic unit through which water can move
  easily (i.e. its permeable)( high
  permeability)
• Porosity how much water a geologic material can
  hold

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Opposite of an aquifer?

• Aquitard / aquiclude
• retards the flow of groundwater (its almost
  never really zero

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Groundwater aquifers

• What would be the properties (porosity/permeabilit
  y) of conglomerate?
• High porosity, high permeability

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Groundwater aquifers

• What would be the properties (porosity/permeabilit
  y) of unfractured granite?
• Low porosity, low permeability

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Groundwater aquifers

• Can you think of a rock/sediment with high
  porosity and low permeability?

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Groundwater aquifers

• Can you think of a rock/sediment with low
  porosity and high permeability?

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How is this possible?
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Ground Water and Surface Water

• These are almost always connected
• If a stream contributes water to the aquifer its
  called a losing stream
• If a stream receives water from the aquifer its
  called a gaining stream
• Same stream can be both at different places or at
  different times

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Pumping Animation

• Go to animation at http//almandine.geol.wwu.edu/
  dave/courses/2003/spring/101/lectures/water_level
  .swf

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Your WarmUp AnswersPart B Pumping wells

• That was a really cool animation but I just dont
  understand what is happening.
• Lets look at the situation again go!

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Your WarmUp AnswersPart B Pumping wells

• In the low permeability case the water is pumped
  primarily from the area directly around the well,
  whereas with the higher permeability the water
  seems to be drawn from a more broad area
  surrounding the well "hole". Since permeability
  refers to the ability of a material to let a
  fluid move through it, the low permeability
  doesn't allow the water to venture far from the
  path of pressure change (the "hole" of the well).

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• What happens when this well is heavily pumped?

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Pollution of Groundwater

• Need a sense of ground water flow
• warmup responses to The velocity of groundwater
  flow is dependent on
• porosity and permeability 28
• permeability and hydraulic gradient 61
• porosity and hydraulic gradient 7
• pressure gradient 4

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Groundwater Flow

• Groundwater velocity
• Depends on permeability and hydraulic gradient
  (slope of water table)
• Ranges from 100 m/day to mm/day
• A good round number 1 ft/day

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• What happens when a new well here is heavily
  pumped?

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Flow direction can change