Upcoming topics

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Upcoming topics

• Today Rivers and Streams
• Monday Flooding!
• Wednesday Ground Water

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Homework Due Now

• Key posted on supplemental web site today

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Todays Plan

• The hydrologic cycle
• Today we begin a survey of water on earth
• streams, floods, groundwater, glaciers, beaches
• Streams
• Watersheds stream flow measuring
• Sediment transport
• Stream processes erosion deposition

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The Hydrologic Cycle - Reservoirs

• Think in terms of reservoirs
• Can you name them all?
• Ocean, surface water (rivers and lakes), ice caps
  glaciers, ground water, atmosphere, biosphere,
  and...
• crustal minerals!
• also, deep earth (but its not really in the
  cycle)

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The Hydrologic Cycle - Fluxes

• fluxes move water between reservoirs
• Amount of water leaving the reservoir per unit
  time
• Evaporation, transpiration, (condensation)
  precipitation, infiltration, runoff
• Residence time (time water spends in res.)
• size of reservoir / flux

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The Hydrologic Cycle
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Reservoirs and Fluxes the ketchup example

• Restaurant marries 60 ketchup bottles daily and
  adds 4 new bottles
• What is the residence time of ketchup in this
  restaurant?
• What is the probability (in ) that the bottle
  you get is new?
• Would you eat at this restaurant?

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Reservoirs and Fluxes the ketchup example

• residence time?
• 60 bottles / 4 bottles per day 15 days
• probability (in ) of new bottle?
• For any day 4 of 60 bottles are new, so4/60
  0.067 6.7
• Would you eat at this restaurant?
• Residence time at your house / apartment?

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River Size / Speed

• What controls this?

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Drainage Basin or Watershed
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Watershed

• Why should we care about a watershed?
• Drinking water - amount, quality
• Floods
• Groundwater

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Discharge and the hydrograph
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Discharge and the hydrograph

• How to find USGS real-time discharge data
• Begin at http//waterdata.usgs.gov/wa/nwis/

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How does sediment move?

• Three sediment loads in a stream
• Bed load is dragged / rolled / shoved along the
  stream bed
• Suspended load is floated in the turbulent
  water
• Dissolved load is carried as ions in solution

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cut bank
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Stream Evolution
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Stream valley shapes

• V-shaped Young stream, eroding down

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Stream valley shapes

• V-shaped Young stream, eroding down
• Butstreams can only erode their beds.
• Makes valley deeper
• How does the valley get wider?

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Stream valley shapes

• Slot-canyon Young stream, eroding down, no mass
  wasting

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Stream valley shapes

• Flat-bottom Mature stream, graded, with
  floodplain and meanders eroding banks.

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Go to Flash Stream Animation
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Newaukum River (WA)
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What is this base level thing?

• Apparently simple concept, that baffles most of
  us.
• Tells whether a stream is eroding or depositing
  at a given location
• Tells what will happen if we disturb the stream
  somehow.

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Stream Profile
(Graded)
Base Level
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Dams cause deposition
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Decreasing Sea Level causes erosion
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Terraces

• Uplifted river deposits

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Terraces