BC WATER NEWS EXCLUSIVE
 
 

August 31, 2006

A Mighty Bold River Remedy

Scientists propose aggressive action to restore Louisiana's collapsing coast

by Richard Hellmann | BC WATER NEWS

NEW ORLEANS — A coalition of scientists, engineers and technical experts laid out a bold and visionary proposal June 1 to restore the Louisiana coast, an effort that hinges on a $2 billion authorization bill as part of the Water Resources Development Act being debated in Congress.

The focal point of the massive plan would create channels along the Mississippi River between Myrtle Grove and Venice, collecting the 120 million tons of sediment lost each year to the Gulf of Mexico and using it to rebuild, replenish and sustain the state’s southeastern coast. Without sediment, the coastal marsh subsides and erodes, falling off the Gulf shelf and becoming open water.

These vanishing wetlands — most notably Plaquemines Parish — are the first line of defense against Mother Nature, and the coalition used the first day of the 2006 hurricane season to remind everyone of the urgency to repair this delicate but collapsing ecosystem. “Without aggressive action to restore its coast, the future is bleak for Louisiana,” Denise Reed, an environmental sciences professor at the University of New Orleans and head of the technical group, said in a prepared statement.

“Even if we can protect populated areas from hurricanes with levees and floodgates, the continued loss of the coastal landscape will pose an increasing threat to the economy and environment of the region,” she said. “Land loss and flooding will become even more severe as sea-level rise accelerates and storms increase in intensity.”

"Without aggressive action to restore its coast,
the future is bleak for Louisiana."

Denise Reed

Redirecting the main flow of sediment and fresh water from the Mississippi River closer to shore would allow tides and waves to transport the sediment and rework it into a mosaic of wetlands, shallow bays and barrier islands, the scientists say. Of course, this is a costly and time-consuming approach, but one that Reed believes is vital.

Vince Neary, an associate professor of civil and environmental engineering at Tennessee Tech University, says the state's coastal wetlands act as natural speed bumps against hurricanes and storm surges. Mining and diverting sediments on a smaller scale would slow land loss, but would not sustain the landscape, the report emphasizes.

"If you really are serious, that's how dramatic the plan has to be," Neary said in a university press release. "Itsy-bitsy fixes won't cut it anymore."

His colleagues in the technical group agree.

“A lot of proposals are out there that are less radical, but they’re small” says Bill Dawson, P.E. “They’re not fast enough or good enough. The river solution is a massive project, to get a deep channel all the way to the Gulf. It’s going to take some time to do that.”

The technical group’s report helped sort out the priorities for coastal Louisiana, Dawson says. “Technical solutions are fairly easy to come up with, but implementing them will be the difficult part.”

Mike Fowler, P.E., a water resources engineer, agrees with the technical group’s solution. “It’ll work as long as the navigation for the Mississippi River is adequate and maintained,” he says. “I’d be surprised if there’s significant support for an approach that doesn’t support navigation.

“We’ve interrupted a natural process … of the coastal land area, and have accelerated the loss of these areas. We have to somehow reinstitute the land-building process that’s been interrupted.”

A new storm of debate is likely over navigation, though, as the U.S. Army Corps of Engineers prepares to study closing “hurricane highway” to ships.

The group’s report outlines three scenarios:

  • Continuing Current Management highlights that without aggressive action in the short term, the long-term outlook for the coast is bleak: higher and wider levees, haphazard retreat and substantial loss of habitat and protection for the nation's energy infrastructure.
  • Achieving a Sustainable Louisiana outlines the urgent need to capture and divert the 120 million tons of Mississippi River sediment a year that slips off the continental shelf in the deep Gulf waters. The idea is to redirect the main flow of sediment and freshwater from the river and allow waves and tides to re-establish a mosaic of wetlands, shallow bays and barrier islands.
  • Achieving Sustainability and Addressing Local Restoration shows how, by using all available Mississippi River sediments as the base, the existing plans for coastal restoration, such as those put forth in the Louisiana Coastal Area study, can address local restoration needs.

The report cautions that the river sediments are “not sufficient to rebuild and maintain the entire coast” and warns that “retreat from some areas must be expected and planned for.”

Louisiana Gov. Kathleen Blanco said that the state is better prepared for storm surges this time around, but “we don’t have a federal commitment to coastal restoration. We must have a restored coastline.”

In April 2006, the technical group of more than 30 scientists and engineers participated in a symposium, "Envisioning the Future of the Gulf Coast," that brought together experts in geology, ecology, oceanography, engineering and economics from across the United States, as well as Italy, the Netherlands, the United Kingdom, Egypt and Australia.

At that conference, Neary said the consensus was to present one map recommending diversion of the extreme lower Mississippi River east and west to harness the sediment and rebuild the area's ecological system and natural protection.

"The main challenge that comes with this solution is how to maintain the navigation channel that supports the transportation of oil, gas, grain and other commodities," Neary explained. "Even with a consensus on what the best plan should be, we can't rely on just one strategy. We also have to entertain augmenting sediment and freshwater diversion through the Atchafalaya River and Bayou Lafourche, distributory channels that discharge west of the Mississippi River outlet."

Neary served as the main design engineer for the Napa (Calif.) River Estuary flood project, known as the Living River Strategy. In that project, some levees in strategic areas were taken down to restore natural floodplains and lower water levels upstream. This plan also reduced erosion.

"Traditionally, we had to be very conservative and not take chances with large-scale changes in river systems, but better modeling tools allow us to consider broader options that take in environmental concerns, like preserving the salt marshes, while at the same time maintaining acceptable flood protection," he said.

“We have the science and engineering tools to develop and implement a viable strategy, but do we have the political will to do what it takes?" Neary said.

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