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.