Justin Mapula
Leslie Darnell
Gary Trubl
Amanda Rutherford
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
Overview: Wetland Functions Erosion control
Vegetation acts as flood buffer and supports soil
Silt catcher Groundwater recharge/water purification Recreation, etc.
Storm Buffering
Site-specificGeneral: 2-4 linear miles of coastal wetland
reduce storm surge by 1 foot○ Does not take into account storm intensity
(especially >Category 3) or coastal elevation
Hurricane velocity decreased Wetland cycle
Disturbance-dependent
1986-1997: 58,500 acres/yr lost
Flood Control Control hydrologic pathways
Precipitation, surface runoff, groundwater, tides, flooding
Reduces velocityNaturally slows as water dissipatesVegetation
Floodwater storageReduction of peak flowsSlow releasePercolation
Flood Control Continued
Habitat modifiers Beaver dams
Self-compounding issueReduction of primary and secondary
production as a result of channelization and damming
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
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
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.
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.
Man Made Hurricane Protection
Past Present Future
Is It Effective?
Money
Time
Global Change
Natural Wetland Protection
Barrier IslandsCypress MarshesVegetation buffer zones
Is It Too Late? Money Irreversible Damage Government Backing
References
Middleton, B. “Wetland restoration, flood pulsing, and disturbance dynamics” Wiley and Sons. 1999. EPA “Importance of Wetlands” <http://www.epa.gov/bioiweb1/aquatic/importance.html>. Louisiana Hurricane Resources http://www.laseagrant.org/hurricane/archive/wetlands.htm#Q2 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. <http://www.ncseonline.org/nle/crsreports/06Mar/RL33117.pdf>. Desmond, John M., . "The Dying Louisiana Wetlands." Pacifica Graduate Institute 485-492. Web. 23
Sep 2009. <http://www.janushead.org/8-2/Desmond.pdf>. The BEST commission National Wetlands Committee, . "The Bahamas National Wetlands Policy." 07
June 1997. Web. 23 Sep 2009. http://www.best.bs/Documents/Bahamas_national_wetlands_policy.pdf.
Bob Sullivan. "Wetlands erosion raises hurricane risks." (Aug 29, 2005): Web. 23 Sep 2009. <http://www.msnbc.msn.com/id/9118570/>.
Holloway, Marguerite. Bringing Back the Barrier. Scientific American Presents; 1999, p. 38-42. http://ezproxy.library.arizona.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=20935664&site=ehost-live
Fischetti M. Drowning New Orleans. Scientific American [serial online]. October 2001;285(4):76. Available from: Scientific American Archive Online, Ipswich, MA. Accessed September 23, 2009.
Fischetti M. Treading Water. Scientific American [serial online]. July 2007;297(1):21. Available from: Scientific American Archive Online, Ipswich, MA. Accessed September 23, 2009.