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Barrier Islands & Wetlands


Why is Louisiana losing its coastal wetlands and how much have been lost?

Louisiana’s coastal land loss problems are caused by a number of natural and man-made factors, but the primary factor has been the leveeing of the Mississippi River for purposes of flood control and navigation. Historically, the river changed course every 1,000 to 2,000 years and balanced Louisiana delta lobe deterioration with new delta lobe formation. With increased settlement in the 1700s, people began building flood protection levees to shield their homes and property. As the levees grew larger, the “wild” nature of the river was restricted. This ultimately reduced the frequency of alluvial flooding and new delta lobe formation that is so critical to the creation and maintenance of wetlands in coastal Louisiana. After the Great Flood of 1927, Congress authorized funding for major Mississippi River flood control projects, including a system of continuous, reinforced levees that allowed for increased settlement and development along the river and its distributaries.

These levees provided the needed flood protection, yet prevented vital land-building sediments and nutrients from replenishing and elevating deteriorating marshes. The result was increased areas of open water and higher rates of erosion and subsidence. Additional alterations to the landscape have compounded the problem. The dredging of thousands of miles of access canals for petroleum extraction and navigation has accelerated saltwater intrusion. Combined with natural causes, such as subsidence and hurricanes, these forces now result in the loss of 20 to 25 square miles of coastal Louisiana wetlands each year. According the U.S. Geological Survey (USGS), Louisiana has had a net loss of 1,900 square miles (about 1.2 million acres) of coastal wetlands in the last century alone.

http://www.seagrantfish.lsu.edu/pdfs/WetlandFunctions.pdf

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 9-21-05

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Was some of the damage from Hurricanes Katrina and Rita exacerbated by the loss of Louisiana’s coastal wetlands?

The answer is probably yes, although quantifying the additive hurricane damages caused by lost or highly deteriorated wetlands is a difficult, if not impossible task. Protection from hurricanes is an often-cited justification for coastal restoration spending, yet this buffering capacity is both site and storm specific. Little is known about how this buffer holds up against storms of a Category 3 or higher magnitude.

Some reports have attempted to quantify this protection as a general ratio. Typically, this ratio is expressed by the number of linear miles of coastal wetlands (usually 2 to 4) required to reduce storm surge height by 1 foot. Yet, such estimates often lack any adjustments for storm intensity or coastal elevation. Anecdotal reports indicate that the deterioration of coastal wetlands has increased the tidal amplitude and duration of coastal flooding in recent years. In these accounts, areas once dry during a Category 2 storm are now reportedly inundated by Category 1 hurricanes and tropical storms.

At a minimum, we can say that the net loss of 1.2 million acres of coastal wetlands has definitely increased the vulnerability and exposure of Louisiana’s critical coastal infrastructure. In the post-hurricane response to rebuild this infrastructure, a concurrent investment will be required to restore the adjacent coastal wetlands that help sustain and protect coastal roads, ports, oil and gas pipelines, and levees.

http://www.nola.com/hurricane/images/scourgeofsurge.pdf

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 10-10-05

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How did Louisiana’s barrier islands fare during Hurricane Katrina?

The eye of Hurricane Katrina passed directly over the 50-mile Chandeleur Island chain. Aerial surveys conducted by U.S. Geological Survey on Sept. 1 show that these islands were heavily damaged by the storm. Initial estimates suggest that Katrina reduced the Chandeleur Islands by one-half of their pre-storm land area. Although barrier islands and shorelines have some capacity to regenerate over time, the process is very slow and often incomplete. With each passing storm, the size and resiliency of these areas can be diminished, especially when major storms occur within a short time period. Katrina was the fifth hurricane to impact the Chandeleur Island chain in the past eight years. The other storms were Hurricanes Georges (1998), Lili (2002), Ivan (2004) and Dennis (2005).

Grand Isle was also heavily damaged by Katrina. Though Katrina made landfall more than 50 miles to its east, Grand Isle received extremely high winds and a 12- to 20-foot storm surge that caused tremendous structural damage to most of the island’s camps, homes and business.

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 9-21-05

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What were the effects of Hurricane Katrina on Louisiana’s coastal marshes?

Preliminary analysis of satellite imagery by the LSU Coastal Studies Institute indicates that Hurricane Katrina caused very heavy damage to the marshes south and east of Lake Borgne in St. Bernard Parish. Assessments by the U.S. Geological Survey show that approximately 20 percent (30 square miles) of the land in the upper portion of Breton Sound in Plaquemines Parish has been converted to open water. Despite these initial observations, it is too early to ascertain the full extent of marsh damage caused by the storm. Additional satellite imagery is currently being analyzed to determine the full extent of marsh loss in these and other parishes, including St. Tammany, Orleans, Jefferson and Lafourche. Future observations over the fall and winter will be required to determine how much of these losses will be permanent.

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 9-21-05

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How are CWPPRA, Coast 2050, WRDA, LCA and CIAP different?

In the past 20 years, a myriad of restoration programs have emerged in response to Louisiana’s coastal land loss crisis. Although covering all of these is beyond the scope of this response, some of the major initiatives are described below.

CWPPRA - The Coastal Wetland Planning, Protection and Restoration Act (CWPPRA), also known as the “Breaux Act,” was authorized by Congress 1990 to address wetland loss nationally with a primary focus on coastal Louisiana. CWPPRA is administered by a task force consisting of representatives from the Army Corps of Engineers, Environmental Protection Agency, Department of Commerce, Department of the Interior, Department of Agriculture and the Louisiana Governor’s Office. A total of 149 projects have been authorized through CWPPRA since 1990, benefiting more than 135,000 acres of coastal wetlands.
www.lacoast.gov

COAST 2050 - Coast 2050: Toward a Sustainable Coastal Louisiana is a strategic plan developed in 1998 by the State of Louisiana and several federal agencies. The plan outlines 77 ecosystem restoration strategies that are needed to protect and sustain the remainder of Louisiana’s coastal wetlands. Construction costs of the Coast 2050 plan have been estimated at approximately 10 times the annual level of CWPPRA spending, or $14 billion dollars over the next 30 years.
www.coast2050.gov

LCA – The Louisiana Coastal Area (LCA) Comprehensive Ecosystem Restoration Study was initiated in 2001 as the blueprint for implementing Coast 2050 restoration strategies into a series of large-scale projects for coastal Louisiana. In 2003, however, the scope of the LCA was paired down from $14 billion to $1.9 billion at the bequest of the Bush administration. In 2004, a final LCA report was released that included five “near-term” critical restoration initiatives and additional funding for research and feasibility studies.
www.lca.gov

WRDA - The Water Resources Development Act (WRDA) is the primary mechanism through which the U.S. Army Corps of Engineers is funded for conducting flood control, navigation and environmental restoration projects. The Act is typically reauthorized on a four-year basis. In 2000, WRDA provided a 50 percent federal cost-share for the $7.8 billion Comprehensive Everglades Restoration Plan. Funding for the LCA program has not been forthcoming, however, as Congress failed to pass WRDA legislation in 2004.
www.usace.army.mil/

CIAP – The Coastal Impact Assistance Program (CIAP), Title 371 of the Energy Policy Act of 2005, returns a portion of federal oil and gas royalties to coastal states and counties based on their respective levels of energy production, population and coastline. Under the current version of this title, Louisiana stands to receive $540 million over the next four years for coastal impact assistance.

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 9-21-05

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Are there other areas of coastal Louisiana that are highly vulnerable to hurricanes?

As seen recently, the entire Louisiana coastline - from New Orleans to Cameron - is highly susceptible to hurricanes. Although Louisiana’s coastal marshes and barrier islands provide a front line of defense against storm surge, 90 percent of these wetlands are at or below sea level elevation. Furthermore, Louisiana is historically prone to major storm events. According to the LSU Hurricane Center, the central Louisiana coast has experienced landfall of more major hurricanes (Category 3 and above) than anywhere in the continental U.S. over the past century.

One area that escaped major damage from Hurricanes Katrina and Rita was Port Fourchon in lower Lafourche Parish. The national significance of this commercial port has grown rapidly in recent years. With the advent of Outer Continental Shelf (OCS) drilling technology, Port Fourchon has grown from two to 160 companies in the past two decades. Most of that growth has occurred since 1995 when the port was less than a third of its current size.

A direct hit on Port Fourchon by a major hurricane could have serious consequences to the U.S. domestic energy sector. Port Fourchon serves as the inter-modal support hub for 75 percent of Gulf of Mexico drilling, 16 percent of U.S. domestic oil and gas production and is the nation’s only offshore oil terminal, the Louisiana Offshore Oil Port (LOOP). The vulnerability of Port Fourchon has been widely documented and was recently the focus of the Hollywood docudrama – “Oil Storm.”

The most hurricane-vulnerable aspect of Port Fourchon is LA Highway 1. This substandard, easily-flooded road serves the port and provides the only evacuation route for a population of 35,000 residents and 6,000 offshore workers. The Louisiana Department of Transportation and Development (DOTD) recently initiated construction of a long-awaited overhaul of LA 1. The DOTD project replaces the current road with an elevated highway that will begin at Port Fourchon and stretch 17 miles northward to higher ground.

(Rex Caffey, Louisiana Sea Grant College Program/LSU AgCenter) 10-8-05

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