Unit 1 Louisianas Changing Wetlands

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Unit 1Louisianas Changing Wetlands
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• Introductory Facts
• So. Louisiana contains 40 of total coastal
  marshland in the contiguous United States
• Wetlands provide critical wildlife habitat, food,
  recreation, and fuel to whole country
• A football-field-size piece of Louisiana wetland
  is lost to the sea every 30 minutes25-35 sq mi
  per year in last 100 years

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• What is a river system?
• All the waters feeding into the main river, or
  stem, all waters branching from it
• Tributaries flow into it
• Distributaries flow from it
• Source of Mississippi is in Lake Itasca, MN (450
  m, or 1,475 ft above sea level)
• Mouth of Mississippi is 4,107 km (2,552 mi) later
  in Gulf of Mexico at Louisiana
• Land area drained by river is a drainage basin,
  or watershed

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• How did the Mississippi River create Louisianas
  coastal wetlands?
• River collects everything that runs off
  surrounding land, including pollutants
• Force of the river carries these materials away
  sweeps sediments (mostly of clay, silt fine
  sand) along the rivers path
• Most sediment is deposited at rivers mouth
• Sediments compact subside---process repeated
  over over
• Plants root form a marsh finally, a delta

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This is a photograph taken north of the Marine
Center in Cocodrie on April 9, 2004. (from
website www.lumcon.edu/marsh/)
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• If new sediment is deposited at faster rate than
  the old sediment subsides, new land forms at the
  river delta.
• The river eventually changes direction forms
  new deltahence the 7 deltas up to the current
  Birdsfoot.
• If new sediment isnt deposited fast enough
  before the old subsides, wetlands are lost to
  open water, and salinity replaces freshwater.

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• Why are Louisiana wetlands disappearing?
• Always in a state of gaining losing land due to
  subsidence, wave action severe storms
• Rise in sea level subsidence allows salt water
  to flow into freshwater areas
• Freshwater plants die the marsh dies so land is
  easily washed away
• People have built levees dams to reduce
  flooding so that not enough sediment gets to the
  mouth
• Oil natural gas pumping increases subsidence

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Changes to Birdsfoot Delta
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• Is there hope for Louisianas wetlands?
• Scientists are working on short long-range
  solutions.
• Rachael Sweeney manages variety of projects that
  support natural land-building forces
• Projects depend on work of researchers such as
  Denise Reeddata is used to design the projects
• Fences rock walls slow wave erosion trap
  sediment. Ocean sediment used to rebuild beaches

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• Grasses are planted to hold soil in place.
• Agencies across state trying to restore original
  hydrology (patterns of water flow) by filling in
  canals opening levees, so river water can build
  land again
• Goal is to allow sediment deposition to occur
  through a controlled process of natural flooding

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Experiments/ Activities

• Lets Settle This! p28 (discussion)
• 1.l A Birds-Eye View of Land Change p31
• 1.2 Monitoring the Marsh A Core Issue
  (discussion) p37
• Fieldwork in Your Neighborhood Testing for
  Density Salinity p41 (discussion)