Wetland Losses and Susceptibility to Hurricane Damage in New Orleans

1. Justin Mapula Leslie Darnell Gary Trubl Amanda Rutherford Wetland Losses and Susceptibility to Hurricane Damage in New Orleans

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

3. Importance of Wetlands in Flood Control and Damage Mitigation

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

5. 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 >Category 3) or coastal elevation • Hurricane velocity decreased • Wetland cycle • Disturbance-dependent • 1986-1997: 58,500 acres/yr lost

7. 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

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

9. Causes of Wetland Loss

11. 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

12. 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

14. Consequences of Hurricane damage

15. 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.

16. 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. 

18. Natural vs. manmade controls

19. Man Made Hurricane Protection • Past • Present • Future

20. Is It Effective? • Money • Time • Global Change

21. Natural Wetland Protection • Barrier Islands • Cypress Marshes • Vegetation buffer zones

22. Is It Too Late? • Money • Irreversible Damage • Government Backing

23. 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.