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Louisiana Trip, Engineering
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As we drove
south, we were able to stop and visit several river engineering projects
that have a profound effect on the delta. Older projects were
intended to prevent flooding and improve navigation. More recent
projects are intended to remediate some environmental consequences of
the earlier projects. |
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The most upstream project we visited
was the control structure at old river. Actually a complex of
projects, including a power generation station, this controls the
distribution of water between the Mississippi and its major northern
distributary, the Atchafalaya. Without these structures, many
believe that the Mississippi would have switched its main flow to the
much shorter Atchafalaya channel to the sea. |
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The Bonnet Carre' Spillway,
just upstream from New Orleans, represents one the last ditch, but most
effective ways that flood waters are controlled. This structure
can open a 7,000 foot wide gap in the levee system, diverting water
through a floodway into Lake Pontchartrain. This relieves pressure
on downstream levees. In its natural state, the river had many
such distributaries, and these fed fresh water into Southern Louisiana's
complex of fresh and brackish water marshes. With most
distributaries blocked, saltwater incursion is a problem
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Davis Pond freshwater diversion
structure is an attempt to recreate the effects of natural flooding, and
to regulate salinities in a broad swath of land, roughly from New
Orleans south to the gulf, between the Mississippi and Bayou Lafourche.
Here, students are traveling within the project area in an ACE boat.
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One concerned party
in the area is the oil industry. As much as 25% of the nation's oil
comes onshore across the Louisiana coast, and serious erosion could
jeopardize this infrastructure. Here, along Bayou Lafourche, an offshore
"jack-up rig" is being readied for deployment. We also saw that
canals built throughout the wetlands contribute to the problems of
erosion and saltwater incursion. |
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The Jefferson Parrish Emergency
Preparedness Center houses people who will try to manage the situation
should natural disaster strike the area. We learned that flooding
from the sea during a hurricane is a much more likely problem than
flooding from the river. The computer screen shows the depth of
flooding from a possible storm predicted by computer models. Over
12 feet of water are possible in many thickly settled areas. With
limited highways, it is estimated that it could take as long as 72 hours
to fully evacuate the area, and presently, forecasting cannot predict
storms that far in advance. |
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Next: History & People
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For more information, contact Dr. Tim Lincoln, Institute for
the Study of the Environment, Albion College, Albion MI 49224.
Phone (517) 629-0486 – e-mail tlincoln@albion.edu
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