Wetland Losses and Susceptibility to Hurricane Damage in New Orleans

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Wetland Losses and Susceptibility to Hurricane
Damage in New Orleans

• Justin Mapula
• Leslie Darnell
• Gary Trubl
• Amanda Rutherford

2
Wetland Losses and Susceptibility to Hurricane
Damage in New Orleans

• Importance of Wetlands
• Causes of Wetland Loss
• Consequences of Hurricane Damage
• Natural vs. Manmade Controls

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Importance of Wetlands in Flood Control and
Damage Mitigation
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Overview Wetland Functions

• Erosion control
• Vegetation acts as flood buffer and supports soil
• Silt catcher
• Groundwater recharge/water purification
• Recreation, etc.

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Storm Buffering

• Site-specific
• General 2-4 linear miles of coastal wetland
  reduce storm surge by 1 foot
• Does not take into account storm intensity
  (especially gtCategory 3) or coastal elevation
• Hurricane velocity decreased
• Wetland cycle
• Disturbance-dependent
• 1986-1997 58,500 acres/yr lost

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Flood Control

• Control hydrologic pathways
• Precipitation, surface runoff, groundwater,
  tides, flooding
• Reduces velocity
• Naturally slows as water dissipates
• Vegetation
• Floodwater storage
• Reduction of peak flows
• Slow release
• Percolation

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Flood Control Continued

• Habitat modifiers
• Beaver dams
• Self-compounding issue
• Reduction of primary and secondary production as
  a result of channelization and damming

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Causes of Wetland Loss
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Causes of Wetland Loss In New Orleans, Louisiana

• Losses date back to 1928
• Mississippi River corralled with levees and dams
  in effort to prevent flood damage
• A result of cumulative natural and human-induced
  impacts
• Oil and gas industries
• draining and dredging of wetlands for oil
  industry canals
• Global sea-level rise
• Declining sediment load in the Mississippi River
• Due to upstream dams on the river
• Subsidence
• Cannot be controlled by human intervention
• Storm surges, strong winds
• Example Hurricane Katrina

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More Causes of Wetland Destruction

• Wetlands have also been
• Drained
• Dredged
• Filled
• Leveled and flooded for urban, agricultural, and
  residential development
• Manmade channels and canals
• Causes saline water to flow inland
• Increases water buildup
• Kills vegetation
• Oil activities
• Example oil spillage
• Highway construction in the wetlands
• Alters drainage patterns and fluid withdrawal
  causes subsidence

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Consequences of Hurricane damage
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Effects

• Hurricanes can import new types of plants and
  animals that can destroy wetlands.
• Mess up the pH (most prefer hard water) and
  salinity.
• Debris from hurricanes is left in the wetlands.
• Disrupt the biogeophysical systems and
  ecosystems of wetlands.
• They over-flood the wetlands, causing less
  oxygen and way too much water.
• Wetlands are Sensitive, slight chemical changes
  ruin them (e.g. temperature change).
• Hurricanes are most prominent during the
  draw-down (backwash) of the wave cycle instead of
  the actual wind. This moves the most soil and
  affects the wetlands most.
• In some areas 3 meters of soil can be moved from
  one area.

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• Hurricanes quickly lose force when they hit land,
  but New Orleans is now vulnerable to violent
  storms because the land around it has been
  rapidly disappearing. Today, New Orleans is
  almost completely exposed to the Gulf of Mexico.
  Wetlands act as a "speed bump," slowing down
  storms almost like dry land does. about 1,900
  square miles of wetlands have disappeared from
  the area since the 1930s, and the receding
  continues at a rate of about 24 square miles per
  year.  The erosion has a direct impact on New
  Orleans' ability to absorb the blow of a storm
  like Katrina. For every 2.7 miles of wetlands,
  storm surges are reduced by about one 1 foot. 

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Natural vs. manmade controls
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Man Made Hurricane Protection

• Past
• Present
• Future

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Is It Effective?

• Money
• Time
• Global Change

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Natural Wetland Protection

• Barrier Islands
• Cypress Marshes
• Vegetation buffer zones

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Is It Too Late?

• Money
• Irreversible Damage
• Government Backing

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References

• Middleton, B. Wetland restoration, flood
  pulsing, and disturbance dynamics Wiley and
  Sons. 1999.
• EPA Importance of Wetlands lthttp//www.epa.gov/
  bioiweb1/aquatic/importance.htmlgt.
• Louisiana Hurricane Resources http//www.laseagran
  t.org/hurricane/archive/wetlands.htmQ2
• Hey, D.L. and Phillippi, N.S. Flood Reduction
  through Wetland Restoration The Upper
  Mississippi River Basin as a Case History.
  Restoration Ecology. 2006.
• Sheikh, Pervaze A., . "The Impact of Hurricane
  Katrina on Biological." CRS Report for Congress
  (2006) 1-9. Web. 23 Sep 2009. lthttp//www.ncseonl
  ine.org/nle/crsreports/06Mar/RL33117.pdfgt.
• Desmond, John M., . "The Dying Louisiana
  Wetlands." Pacifica Graduate Institute 485-492.
  Web. 23 Sep 2009. lthttp//www.janushead.org/8-2/D
  esmond.pdfgt.
• The BEST commission National Wetlands Committee,
  . "The Bahamas National Wetlands Policy." 07 June
  1997. Web. 23 Sep 2009. http//www.best.bs/Documen
  ts/Bahamas_national_wetlands_policy.pdf.
• Bob Sullivan. "Wetlands erosion raises hurricane
  risks." (Aug 29, 2005) Web. 23 Sep 2009.
  lthttp//www.msnbc.msn.com/id/9118570/gt.
• Holloway, Marguerite. Bringing Back the Barrier.
  Scientific American Presents 1999, p. 38-42.
  http//ezproxy.library.arizona.edu/login?urlhttp
  //search.ebscohost.com/login.aspx?directtruedba
  9hAN20935664siteehost-live
• Fischetti M. Drowning New Orleans. Scientific
  American serial online. October 2001285(4)76.
  Available from Scientific American Archive
  Online, Ipswich, MA. Accessed September 23, 2009.
• Fischetti M. Treading Water. Scientific American
  serial online. July 2007297(1)21. Available
  from Scientific American Archive Online,
  Ipswich, MA. Accessed September 23, 2009.