Louisiana’s Defense Systems: Wetlands and the Case of the Great Wall of Louisiana

In 2013 the US Army Corps of Engineers (USACE) completed construction of the “Inner Harbor Navigation Canal Lake Borgne Surge Barrier”. The project is funded through the Hurricane and Storm Damage Risk Reduction System (HSDRRS) for southeast Louisiana and considered to be the largest civil works project in corps history. The barrier was built to combat storm surge heights like those observed during Hurricane Katrina in 2005. More commonly known as the Great Wall of Louisiana, engineering innovations like a 1000 foot trestle allowed the project to be completed in about 3 years’ time instead of an estimated 20. The barrier wall is 1.8 miles in distance, 26 feet tall, and at an estimated construction cost of $1.1 billion federally funded dollars.

Louisiana contains 40 percent of the continental United States’ wetland acreage. Coastal wetlands can protect against storm surge energy and flooding by marsh grasses, trees, and soil working as as system. However Louisiana continues to lose wetlands due to problems like subsidence, sea-level rise, sediment deprivation, oil and gas development, and climate change. With an extreme need of wetland preservation, coastal agencies like CWPPRA and USACE are strategizing to combat these issues.

USACE is one of the five managing agencies of the Coastal Wetlands Planning, Protection, and Restoration Act. CWPPRA’s mission is to fund, plan, design, and construct restoration projects in coastal Louisiana at a large and fast pace scale. CWPPRA projects are synergistically funded through partner programs, such as the Inner Harbor Navigation Canal Borgne Surge Barrier to protect, preserve, and restore Louisiana’s coast.

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Levee Systems in Louisiana

As flooding events continue to increase in frequency and intensity, it is essential for the State of Louisiana to continue moving forward in technology and ingenuity for the construction of levee systems.

Since 1718 natural and man-made levee systems in Louisiana have been crucial in attempt to control the “Mighty Mississippi”. The Mississippi River drains 41% of the continental U.S. and more than half of Louisiana’s land is in a flood plain [1]. Therefore, careful planning, construction and maintenance of levee systems in Louisiana must continue to improve.

What is a levee?

According to the Federal Emergency and Management Authority (FEMA) a levee is a “man-made design and construction in accordance with sound engineering practices to contain, control, or divert the flow of water to provide protection from temporary flooding [2].

Some History on levees:

Before European control, natural processes occurred along the Mississippi River in which sediment deposits created natural levees reaching up to a meter or two in height. [3]. Initially, state government required that farmers and land owners build their own levees with ~10-12 cubic yards per day and reaching 75 feet long in some areas [4].

Today, with multiple Acts by the United States Congress, levee systems are professionally implemented by multiple entities to promote control and prevent flooding.

Who is Involved:

There is no one entity solely responsible for levee construction and maintenance in Louisiana [2].  Some entities that share the responsibility include but are not limited to the following:

levee districts

Current Programs including Levee Development and Planning:

Necessary Plans for the Future:

The Louisiana Master Plan for a Sustainable Coast 2017 calls for project  “construction of a levee to an elevation of 15-35 feet around the Greater New Orleans area from Verret to the Bonnet Carre spillway” [5].

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Incremental Improvements recommended by David Muth (A Director of National Wildlife and Fisheries) include [5]:

  • Levee resilience
  • Increased water storage capacity inside levees
  • Public incentive to participate in building raising or relocation programs
  • Restoring the wetland buffers outside levee

A Plan in the year 2009 from Netherland Engineers to CPRA recommended the following [5]:

  • Raising levees to protect from a 500 year event or greater around central New Orleans
  • Raising levees to 1,000-year levels east of the Industrial Canal and on the West Bank.
  • Recommended a new levee and gates along the New Orleans land bridge, into St. Tammany Parish.

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As flooding events continue to increase in frequency and intensity, it is essential for the State of Louisiana to continue moving forward in ingenuity for flood prevention, policy, planning, funding, and coastal restoration efforts.

Additional Links regarding Levees:

 

Work Cited:

[1] ALBL. “Association of Levee Boards of Louisiana”. 24 April 2018, http://albl.org/

[2] FEMA, “Levees – Frequently Asked Questions”.  24 April 2018, https://www.fema.gov/media-library-data/20130726-1803-25045-4819/st_broomelv.pdf

[3] Kemp, Katherine “The Louisiana Environment: The Mississippi Levee System and the Old River Control Structure”. 24 April 2018, http://www.tulane.edu/~bfleury/envirobio/enviroweb/FloodControl.htm

[4] Rogers, David. “Evolution of the Levee System Along the Lower Mississippi River”. 24 April 2018, http://web.mst.edu/~rogersda/levees/Evolution%20of%20the%20Levee%20System%20Along%20the%20Mississippi.pdf

[5] Schleifstein, Mark. “New Orleans area’s upgraded levees not enough for next “Katrina” engineers say”. 24 April 2018, http://www.nola.com/futureofneworleans/2015/08/new_levees_inadequate_for_next.html