NewScientist: New Mississippi delta would limit hurricane damage
[Gary Parker of University of Illinois at Urbana-Champaign and Robert Twilley of LSU in Baton Rouge came up with a proposal to] cut breaches into a levee some 150 km south of New Orleans, Louisiana, and 30 km above where the river empties into the Gulf of Mexico. With the diversions in place, flooding would cause the river to empty into shallow saltwater bays on either side of the river, releasing sediment-rich water to produce new deltas.
Politics is the biggest hurdle, according to both scientists.
“The scientific and engineering barriers are easily overcome,” says Gary Parker, a geologist and engineer at the University of Illinois in Urbana-Champaign, who developed the plan with colleagues. “The big issue is political will”.
… A similar plan, presented to the state of Louisiana and the Army Corps of Engineers in 2005, before Hurricane Katrina flooded much of New Orleans, never gained political support. “It was too bold, too aggressive, and too expensive,” Twilley says.
As usual, the first comment following the post at NewScientist.com is even more “ground-breaking” than the proposal itself.
Hmmmm. I’ll have to show that one to Dr. McCorquodale out at the UNO/ Pontchartrain Institute; he always likes to bring up stuff like that in class (the last one was about water power turbines and how much energy they would potentially remove from the river, etc. possibly altering the river.)
Some of the Coastal Plans for Louisiana (there are several, you know) recommend closure of at least one of the existing passes at the mouth of the Mississippi River, so Parker and Twilley’s proposal is certainly not “off the table” in that regard.
The river and coastal mechanics get pretty complicated though, starting with cutting a watercourse through a landscape artificially (you might already know that the river forms its own levees?) Well, when a channel is cut through topography in an entirely different manner there is a risk that it will take away the soil, particularly where there is enough flow or other motion to mobilize and transport the bank material (e.g. MRGO widening out over the years.)
Furthermore (and this topic could potentially go on forever– hey, EVERYBODY is an expert on coastal restoration these days…) The benefits of projects like freshwater and/or sediment diversions, etc. are widely debatable and the outcomes of these types of projects are themselves difficult to measure. This is not about just cutting water loose into the wetlands, but more a question of managing our actions (and our money) by understanding the processes that affect the river, the coast, and how people live.
Just my $0.02, YMMV
Dave
David Rosenberg, PE