The lower Mississippi River south of New Orleans protrudes into the Gulf of Mexico, and man-made levees line the west bank of the river for 55 kilometers of what is known as the Lower Plaquemines section. There are no levees on the east side of this stretch of the river. Westerink points out that, historically, sustained easterly winds from hurricanes have directed storm surge across Breton Sound into the Mississippi River and against its west bank levees.
“This study clearly shows that the man-built west bank levees on the lower Mississippi River enhance the capture of storm surge by the river,” Westerink said. “The surges are generated by the prevalent easterly winds that are common for regional hurricanes, but they spill into the river. These surges then propagate upriver, endangering New Orleans from the river side.”
As an alternative, the study shows that the lowering of man-made levees along the Lower Plaquemines river section to their natural state, to allow storm surge to partially pass across the Mississippi River, will decrease storm surge upriver toward New Orleans.
“By eliminating the 55 kilometers of man-made levees on the west bank of the river from Pointe a la Hache and Venice, the surges propagating in the river from Pointe a la Hache past New Orleans will be lowered by up to two meters,” Westerink said. “This would save billions of dollars in levee construction to protect communities upriver from Pointe a la Hache.”...
FEMA image of the 17th Street levee in New Orleans
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