Wetlands and Hurricanes

1. Wetlands and Hurricanes By Wynn W. Cudmore, Ph.D. Northwest Center for Sustainable Resources DUE # 0757239 This project supported in part by the National Science Foundation. Opinions expressed are those of the authors and not necessarily those of the Foundation.

2. Wetlands and Hurricanes Hurricane Gustav 25 August – 1 September 2008

3. The Gulf Coast Louisiana, Mississippi, Alabama and Florida

4. The Lower Mississippi River Basin is probably the most human-impacted large water basin in the world: • Logging of forested wetlands • Conversion to agriculture • Altered hydrology • Extirpation of megafauna • Fragmentation of the Mississippi River delta • Only about 3.7% of the original wetlands in the basin remain in a natural condition • Largest intact wetland is the Atchafalaya Swamp 1882 2000 10% Forest remaining

5. Wetlands of the Gulf Coast

6. Intact wetlands of coastal Louisiana 1. Barrier islands 2. Brackish wetlands 3. Swamps 4. Freshwater marshes 5. Bottomland forests Louisiana contains over 40% of wetlands in the lower 48 states

8. New Orleans's growth has required draining wetlands and a complex system of levees, pumps and canals New Orleans, Louisiana 29 April 2008

9. Historical Development of New Orleans, Louisiana

13. Wetlands as buffers to storm surges Every 2.7 miles of wetland lowers storm surge by one foot Barataria Bay, Louisiana

14. Wetland Loss along the Louisiana Coast 1999 Over the past few centuries 25% of wetlands associated with the Mississippi Delta have been lost to the ocean 1976

15. Causes of Gulf Coast Wetland Loss Levees and dams direct sediment out into the Gulf of Mexico rather than to wetlands Sediment flowing from the Mississippi River into the Gulf of Mexico

16. 2. Canals cut into coastal wetlands allow saltwater intrusion 3. Sea level rise due to climate change Oil gas extraction rig among eroding wetlands in coastal Louisiana

17. Barrier islands also protect the Gulf Coast Chandeleur Islands

18. Hurricane Katrina 28 August 2005 Category 5 hurricane One day before landfall

19. Hurricane Katrina 29 August 2005 Landfall as a Category 3 storm

20. Katrina’s impact Failed levee Fishing boats on levee Flood damage New Orleans flooded Damage to Hard Rock Casino

21. The impacts on wetlands from Hurricanes Katrina and Rita (2005) Rita’s impact was less severe with some marsh impact west of the Mississippi River Katrina transformed 217 square miles of marsh into open water Before After

25. Mississippi Delta - Before and After Katrina 31 August 2005 Post-Katrina 9 August 2005 Pre-Katrina

26. Impacts of Katrina on the barrier islands Land area of Chandeleur Islands decreased from 5.6 mi2 to 2.0 mi2

27. Impact of hurricanes on the Chandeleur Islands, Louisiana July 2001 Pre-Hurricane Lili (2002), Ivan (2004), Dennis (2005), Katrina (2005) 31 August 2005 2 days post-Hurricane Katrina

28. Hurricanes as agents of renewal Baldcypress (Taxodium distichum) and water tupelo (Nyssa aquatica) were mostly unaffected by the storm Katrina wind damage in Pearl River Basin, Mississippi – late 2005

29. Impact of Hurricane Katrina on Coastal Forests After Katrina Before Katrina Green – intact forests Red – storm-damaged forests

30. Wetland restoration as a strategy • Wetland restoration will require an increase in the sediment load of the Mississippi River • Current sediment load is 50% lower than historic levels • Sustaining current levels of wetlands will require an additional 18-24 billion tons of sediment per year • Future wetland loss seems inevitable

31. The “Coast 2050” Wetland Restoration Plan • Diverts a portion of the Mississippi River to deliver more sediment to wetlands south of New Orleans • Levees below New Orleans opened to increase sediment and freshwater flow into marshes • Close the Mississippi Gulf Outlet • Oil and gas channels to be filled • Sediment builds and wetland grasses replanted as needed • Barrier islands replenished with dredged material

32. Marsh terraces as a conservation practice • Earthen terraces are constructed to reduce wind and wave energy in shallow open water • Facilitate establishment of submerged aquatic vegetation • Each terrace is approximately 1000 feet long, 40 feet wide at the base and 10 feet wide at the top • Surface of the terrace is 2 feet above water level and planted with native vegetation • Arranged in “V”-shaped patterns in shallow, open water

33. Marsh terraces Marsh terraces captured vegetation and soil displaced by Hurricane Rita The resulting increase in elevation may assist in the marsh-building process Marsh terraces built in Little Vermillion Bay, Vermillion Parish, Louisiana. 

34. Marsh terraces Marsh terraces in Vermillion Bay, Louisiana after several growing seasons

35. Marsh terraces as a conservation practice • Earthen terraces are constructed to reduce wind and wave energy in shallow open water • Facilitate establishment of submerged aquatic vegetation • Each terrace is approximately 1000 feet long, 40 feet wide at the base and 10 feet wide at the top • Surface of the terrace is 2 feet above water level and planted with native vegetation • Arranged in “V”-shaped patterns in shallow, open water • Create habitat for fish and wildlife species

36. Hurricanes and Gulf Coast Wetlands – a summary • The Gulf Coast is vulnerable to damage from hurricanes due to its location, elevation and loss of wetlands and barrier islands • Wetlands and barrier islands provide significant protection against major storms • Wetlands have decreased in area due to natural and human-caused events • Hurricanes result in the loss of additional wetlands and barrier islands, some of which is likely permanent • Wetland restoration will require additional sediment input, which the current system cannot provide • The “Coast 2050” wetland restoration plan proposes to alter the hydrology of the Mississippi River Delta to reverse wetland loss

37. Photo Credits • IAN Image Library (ian.umces.edu/imagelibrary/): Tim Carruthers • Louisiana State University Hurricane Katrina and Rita Cooperative Clearinghouse. • Marine Photobank: David Helvarg, Blue Frontier Campaign, ESA Envisat • NASA/courtesy of nasaimages.org • Jesse Allen, Earth Observatory, using data provided courtesy of Laura Rocchio, NASA Landsat Project Science Office • NASA Earth Observatory • NASA/GSFC/LaRC/JPL, MISR Team • Image Science & Analysis Laboratory, Johnson Space Center • GOES Project Science Office • National Oceanic and Atmospheric Administration/Department of Commerce: Dr. Terry McTigue, NOAA Fisheries • U.S. NAVY • USDA Natural Resources Conservation Service: Lynn Betts, • U.S. Geological Survey: National Wetlands Research Center

38. Additional Slides The following slides are provided as additional evidence of the impacts of Katrina on wetlands

39. The impacts on wetlands from Hurricanes Katrina and Rita (2005) Katrina transformed 217square miles of marsh into open water After Rita’s impact was less severe with some marsh impact west of the Mississippi River Before

40. Mississippi Delta –Before and After Katrina 4 September 2005 6 days post-Katrina 9 August 2005 Pre-Katrina

41. New Orleans –Before and After Katrina 30 August 2005 27 August 2005

42. New Orleans –Before and After Katrina 31 August 2005 2 days post-Katrina 27 August 2005