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Louisiana Coastal Erosion

Louisiana Coastal Erosion. Rate of Land Loss. Each year, Louisiana loses about 25 square miles of land due to coastal erosion. This translates to a loss of one football field of wetland every 38 minutes (DNR). Katrina and Rita - 2 days – loss of over 200 miles of wetland.

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Louisiana Coastal Erosion

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  1. Louisiana Coastal Erosion

  2. Rate of Land Loss • Each year, Louisiana loses about 25 square miles of land due to coastal erosion. This translates to a loss of one football field of wetland every 38 minutes (DNR). • Katrina and Rita - 2 days – loss of over 200 miles of wetland.

  3. In the continental U.S., Louisiana accounts for 26% of total marshes and 40% of coastal tidal marshes. Louisiana is experiences 90% of the total coastal marsh loss in the U.S. Louisiana’s Wetlands

  4. Protection from Storms Filter Water Habitats Nursery for Shellfish and other animals Recharge Ground Water Supply Marshes used to be thought of as wasteland – now we know marshes are extremely valuable when left alone. Why are Wetlands Important?

  5. Vanishing Louisiana Theatre

  6. Sea level is rising due to the melting of glaciers.

  7. Predictions of changes with 1 meter rise in sea level: areas in red would be under water

  8. Levees • Levees confine the Mississippi River to its current path, preventing the annual spring flooding that deposited invaluable sediment and nutrients to wetlands.  • Although human civilization has generally thought of flooding as “bad” –the prevention of flooding has “starved” our wetlands.

  9. The value of Mississippi River Mud The levee system prevents most flooding –but long term costs have been high. The nutrient rich mud is now deposited in the Gulf of Mexico, starving the nearby wetlands that not only provide much to the state but protect it from storms and hurricanes.

  10. Floodwater carries nutrients and sediment • Sediment settles • Plants take root • Plants trap more sediment • Biomass increases • Wetlands formed and replenished

  11. Subsidence • Subsidence is a natural process of ground settling. In wetlands systems, subsidence is typically offset by the accumulation of new sediments during spring floods. But because spring flooding no longer occurs, new sediments don’t accumulate, and subsidence gains the advantage.

  12. River Channels • Over the last 200 years, industry and residents alike have cut numerous channels and canals through the wetlands for transportation and oil exploration. • With more channels, salt water has more avenues for invasion.

  13. Saltwater Intrusion • The result of rising sea level and channeling is saltwater intrusion. Freshwater and brackish coastal wetlands are very complicated ecosystems. The intrusion of salt water, can offset the balance and rapidly destroy wetlands.

  14. Tree killed by saltwater intrusion on the coast of Louisiana.

  15. Cypress dead from saltwater intrusion, near Theriot, Louisiana

  16. Barrier Islands • Louisiana’s barrier islands are the first line of defense against hurricanes and tropical storms. As they have degraded over time, their protective nature has grown weaker. Additionally, the islands are key habitat for several wildlife species.

  17. Barrier islands protect the mainland from storm damage. Barrier island

  18. Top pictures are a barrier island before Hurricane Andrew and the bottom pictures are after (1992) The arrows are pointing to corresponding points.

  19. Katrina and Rita land loss

  20. Types of Coastal Restoration Projects River Diversions – channel freshwater from rivers into adjacent areas to replace water, nutrients, and sediment Planting vegetation – planting flood tolerate marsh plants that help to hold the soil in place by their roots

  21. Types of Coastal Restoration Projects (cont’d) Shoreline protection – placing rocks or fences as breakwaters to decrease wave action which causes erosion Christmas tree “fences” – placed in shallow bay areas causing the trapping of sediments and nutrients to create new marshes

  22. Christmas tree fence

  23. Marsh Maneuvers – a program sponsored by La. State Univ. Agricultural Center Students planting marsh grass

  24. Resources • http://www.greynet.org/images/GL8_Costello.ppt#293,2,Louisiana’s Wetland • http://dels.nas.edu/osb/briefing/louisiana_briefing.pdf • http://www2.selu.edu/orgs/pbrp/redesign_documents/powerpoint_lanier.pdf • http://www.nogs.org/2006_october_RDokka.pdf • http://el.erdc.usace.army.mil/lcast/pdfs/06sep/LA101.pdf • http://el.erdc.usace.army.mil/lcast/pdfs/06sep/LA101.pdf • http://www.restoreorretreat.org/coastal_erosion.php

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