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Will it take redirecting the mouth of the Mississippi River in order
to keep the Louisiana coast a viable place to live and work in the
wake of Hurricane Katrina?
Vince Neary, associate professor in our Civil
and Environmental Engineering department, says such a bold, large-scale
plan is necessary to stop the disappearance of the state's coastal
wetlands — which act as natural speed bumps against hurricanes
and storm surges.
"If you really are serious, that's how dramatic
the plan has to be," says Neary. "Up until now, the constraints
of special interests of all types have driven the solution to piecemeal
wetland mitigation and restoration projects. Now, the solution must
drive the actions of everyone, and special interests will have to
adapt. Itsy-bitsy fixes won't cut it anymore."
Neary met with dozens of fellow technical advisors,
scientists, engineers, government representatives, oil and gas industry
leaders and special interest group members last week at a conference
designed to hammer out a dramatic, realistic solution for saving
Louisiana coastal wetlands. According to America's Wetland organization,
Louisiana loses 24 square miles of coastal wetlands each year, the
equivalent of a football field every 30 minutes, due to loss of
sediment buildup that used to occur naturally.
At the conference — Envisioning the Future
of the Gulf Coast — groups were charged with creating maps
and accompanying commentary that address the best workable solution
for sustaining the coastal ecosystem and reducing the damage from
storm surges. Neary says the consensus was to present one map recommending
diversion of the extreme lower Mississippi River east and west to
fully 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,"
explains Neary. "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."
River management techniques in the past 50 years
have in part set up the scenario that played out during Hurricanes
Katrina and Rita. Levees, which protect economic interests and personal
safety, also have arrested the natural sediment accretion process
that builds coastal marsh. Instead, the sediment is jetted out into
the gulf. Without sediment, the coastal marsh subsides and erodes,
becoming open water.
Why not let nature take its course? Neary says
very little about the way the Mississippi currently flows is natural;
the natural process has been arrested for decades to protect cities,
promote navigation and reduce flood damages. Had nature had its
way, New Orleans and Baton Rouge would be stranded major shipping
ports.
"A river is very dynamic, especially at the
outlet, and it changes directions once the sediment it carries and
dumps builds up," says Neary.
Neary says a detailed study would have to determine
where, between the towns of Diamond and Venice in the Plaquemines
parish (See map at www.enlou.com/maps/plaquemines_map.htm),
the best place would be to divert Mississippi sediments east and
west.
"It would also probably depend on whether
the present mouth of the Mississippi (through the bird's foot delta)
could be maintained as a slack water (a stretch of water without
current) navigation channel," Neary continues. "Maintaining
a navigation channel is critical. Until this is studied in detail,
the specific location or locations for diverting the Mississippi
cannot be specified."
Neary speaks from experience, having served as
main design engineer for the Napa River Estuary flood project in
California, known as the Living River Strategy because it incorporated
river and tidal wetland restoration as part of the overall strategy
for flood damage reduction. 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.
"The Napa plan, as will be the Mississippi
River plan, is still very 'engineered,' and both require accurate
modeling and monitoring in order to accurately predict what effects
will occur," says Neary. "Hurricane Katrina has made it
a higher priority now for the country to find time and money to
commit to developing accurate models, plus or minus inches, not
feet.
"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 says.
"Environmentalists have been marginalized
on this topic to a large extent for decades, even though these management
and restoration issues have been on our radar for a long time,"
says Neary. "Only in the last five years or so, and certainly
after Hurricane Katrina, have those with an economic stake in the
area started to listen and communicate with environmentalists."
The group's map and recommendations will be presented
to Louisiana's governor on June 1, the official start of hurricane
season.
During the conference sponsored by British Petroleum,
Neary and other participants toured the coastal area in Black Hawk
helicopters and by boat to see the damage firsthand. Neary says
the conference concluded with one theme articulated by speakers
representing government, the oil and gas industry and other special
interest groups.
“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?" asks Neary.
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