Coastal proposal is a two-for-one idea; Hurricane defense, restoration combined

By: Mark Schleifstein, Staff writer, The Times-Picayune (New Orleans) 

January 10, 2006

An independent group of scientist and engineers is working on a coastline strategy that could help planners in combining coastal restoration efforts with improved hurricane protection in a "multiple lines of defense" approach for New Orleans and other parts of Louisiana.

John Lopez, director of the Lake Pontchartrain Basin Foundations's coastal sustainability program, said the idea is to give federal and state planners a conceptual map that can be used as a template in coordinating restoration and levee projects.

The map would be drawn to identify areas where natural resources need to be protected, as well as noting geological structures that could be used to anchor the restoration and hurricane-protection projects. It also could help in determining what the future uses of the coast-- freshwater or saltwater fisheries, oil and gas production, residential development-- should be, Lopez said.

It may also become a starting point for the controversial decisions about which areas will be ringed with levees and open for development and which areas will be targeted for wetland restoration outside the levee system.

"It's not just a question of identifying what we're defending against, but determining how to get the most out of the restoration program," Lopez said. "If you don't understand the architecture of the coast in geologic or hydrologic terms, you're planning for marsh acreage here or levee heights there without really knowing how one will influence the other."

An expanded effort

Lopez, formerly of the Army Corps of Engineers, began the mapping process as part of the foundation's development of the basin sustainability plan, and expanding to to include a larger area of the coastline after hurricane Katrina hit in August.

For the natural resource parts of the map in the New Orleans area, he looked at studies and maps outlining how the land, wetlands, forests and open water were used between 1900 and the 1930s, before the construction of major projects such as the Mississippi River-Gulf Outlet dramatically changed the local environment.

The independent mapping effort surfaces as the state's new Coastal Protection and Restoration Authority staff is negotiating an agreement with the Army Corps of Engineers that will outline the state's role in the newly combined levee and coastal restoration planning effort recently approved by Congress, said Sidney Coffee, the authority's executive director.

Meanwhile, a separate committee of nationally recognized scientists and engineers led by University of Maryland Center For Environmental Science President Don Boesch is putting together its own advisory report for the corps' Washington headquarters staff. It seeks to intergrate planning for coastal restoration, flood protection and navigation along Louisiana's coast.

"The corps at the a national level was a little frustrated by the critical thinking they were not able to get from the district of division, and they wanted to move the process forward quickly," Boesch said.

His report, to be published within the next few weeks under the auspices of the corps' Institute for Water Resources, will identify problems the corps could face in designing projects, such as the potential for damming off wetlands necessary to maintain productive fisheries, Boesch said.

"We're not doing a map, but making suggestions on how to do a map." he said.

The lines of defense

The focus on using maps to help plan the future of Louisiana's coastline was a key recommendation of a 12- member panel of scientists and engineers sponsored by the National Research Council. That committee, whose November report critiqued the federal-state Louisiana Coastal Area Ecosystem Restoration plan, said the lack of the map represented a failure of state and federal officials to make key decisions about how the state's coastal resources would be used in the future.

Without those decisions, the report said, officials would continually run the risk of political defeats of individual projects by special interests in coastal communities.

Lopez's map identifies 11 separate lines of defense that stretch from the Gulf of Mexico to the interior of cities such as New Orleans:

-- The Gulf of Mexico's Outer Continental Shelf. Understanding how the geography of the shelf affects storm surge is important in hurricane protection planning, Lopez said.

--  Barrier islands. The slivers of sand, such as Grand Isle and the Chandeleur islands, are the first speed bumps with potential for reducing the effects of storm surge and waves, especially on nearby interior marshes. The last remnants of old river deltas, many of the islands along Louisiana's coast have disappeared or are disappearing through erosion and subsidence. Repairing eroded islands and building new ones are among projects being considered in federal and state restoration plans.

--  Sounds and bays. Their shallow water helps reduce currents found in deeper waters, although they allow waves to regenerate as a hurricane crosses them. They also provide sheltered areas for fisheries and other wildlife.

--  Marsh and land bridges. Located in strategic areas along Louisiana's southeaster coast, such as teh area in eastern New orleans bordering Lake Catherine, they can break storm surge. Many are threatened by erosion, and some have been proposed as routes for new or raised levees.

--  Natural ridges. Often the remains of ancient courses of the Mississippi River or its distributaries, the ridges have acted as another speed bump to storm surge and a separation between different water bodies. Some, such as the shoreline of Bayou Lafourche, are where linear communities have located. Others have been cut by navigation channels and have exacerbated erosion. Bayou la Loutre in St. Bernard Parish, for example, was cut by the Mississippi River-Gulf Outlet.

--  Man-made soil foundations. As roads and railroads were built across south Louisisana, compacted materials were used as foundations for roads and railroad beds. Those structures, such as the roadbed of U.S. 90 along the West Bank leading to Houma, continue to provide some protection from surge or floodwaters, or at least a usable escape route.

--  Flood gates. Some gates, such as on Bayou Bienvenue and Bayou Dupre in the New Orleans area or on Bayou Lafourche at Golden Meadow, already are used to reduce the effects of storm surge. Others have been proposed at the Chef Menteur and Rigolets passes into Lake Pontchartrain as ways to reduce the effects of larger hurricanes.

--  Levees. Designed as the barrier of last resort, they also have the consequence of increasing the water levels on their interior side during wetter storms and if they are topped by surge.

--  Pumps. Often used to reduce flood risk within leveed areas during non hurricane events, the stations' effectiveness is reduced because of lack of power or staff during hurricanes.

--  Elevated homes and business. Often used along teh coast in areas unprotected by levees, elevating homes above the level of storm surge is a last line of defense for individual property owners.

--  Evacuation routes. Lopez said the area's evacuation routes and plans need to be part of the planning process to assure that the lowest spots subject to flooding well in advance of storm are raised and that other projects don't impede evacuees.

Limited mandate

Gregory Miller, a coastal restoration project manager for the Corps of Engineers, said such outside assistance will be considered, but that the congressional authorization the corps is working under only calls for integrating storm protection, coastal restoration and flood control, and not the development of a map.

Robert Twilley, a Louisiana State University scientist whose computer modeling has been used to help determine what projects to include in the proposed federal-state coastal restoration plan, said the difficulty with drawing the map will be determining what areas to protect.

"These walls of levees are great for urban areas like New Orleans, but what do you do about Houma and smaller communities, or the chenier plain on the western side of the state," he said. "Do you wall off the entire state?"

Twilley, who is a member of Boesch's group, said ongoing studies of storm surge and waves emanating from observations made during Hurricane Katrina also could change some of the assumptions used in drawing the Lopez map or future maps.

"We're now getting some validation and verification of certain models, and it may be that the actual reduction in storm surge by wetlands and the conveyance of storm surge by canals may differ from past assumptions," he said. "There's some overestimates of what wetlands can do to reduce the magnitude of storm surge."

That could mean more wetlands will be needed, not just to buffer levees, but to protect evacuation routes such as U.S. 90.

"We have to have a natural landscape, not just an apron around the bottom of levees," he said.

Forward to the past

And in areas like the highly eroded marshes adjacent to the MR-GO, it could also require the re-establishment of the large cypress-forest wetland of the past, he said.

Lopez's use of a 1900-1930 period as a target for restoration also could be a matter of debate, said Denise Reed, a University of New Orleans biologist.

"We're dealing with today's natural resources and what they mean to people's livelihoods now, and then what people want their livelihoods to be in the future," Reed said. Going back to a landscape 75 years in the past is "like pickling the coast and putting it in a jar and expecting it to stay the same all the time."

Instead, she said, the Lopez map could be one of a number of maps that sketch out "different strategies for restoration, different strategies for lines of defense and different natural resource productivity, and the different cost associated with them."

"That would inform a discussion about the future of the coast," she said.

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Mark Schleifstein can be reached at mschleifstein@timespicayune.com or (504) 826-3327.