What would the river do? And what would TJ do? According to all scientific studies the next shift of the Mississippi into the Atchafalaya Basin might only a spring flood away. Instead of neglecting the risk the studio explores pro-active measures of how to prepare and compansate for the unthinkable event.
Project 1_MISS!ssippi Sketch Design
Southern Louisiana exists in its present form because the Mississippi River has jumped here and there within an arc about two hundred miles wide, like a pianist playing with one hand frequently and radically changing course, surging over the left or the right bank to go off in utterly new directions. Always it is the river’s purpose to get to the Gulf by the shortest and steepest gradient. The Control of Nature John McPhee, 1989
Introduction: The bigger picture
As John McPhee ends his chapter on the Atchafalaya it is not a matter of if but when the Mississippi will divert into the shorter and steeper path to the Gulf through the Atchafalaya Basin. The 2011 Mississippi spring flood brought this scenario to the fore again. The engineered river system was already at its limit and all floodways had to be operated to not only take the pressure of New Orleans levees, but also of the system of the Old River Control structures. Based on a decision by US-Congress and implemented by the ACOE the Old River Control Structures north of Baton Rouge hold the river back from writing the next piece of history.
The day this structure fails the river will no longer flow in its present channel and New Orleans will be without the Mississippi. The Big Easy will become the Big Salty! Groundwater, wells, drinking water, will no longer be available for residents and for the industry along the Port of Louisiana up to Baton Rouge. The salt water of the gulf will intrude as the land will continue to subside. New Orleans will be an urban island in a salt-marsh. The river with its levees is typically the highest ground in a Delta, for flood protection and navigation the levees were elevated further as the river was channelized. In order to fix the present course of the Mississippi it was harnessed with concrete revetment mats. This gridded mattress lining of the Riverbed will be revealed at the front slope of the levee as the water recedes. Based on this scenario the studio explores response to the following changes over time.
- with the diversion into the Atchafalaya Basin the Mississippi channel at New Orleans will loose its only source of freshwater.
- Saltwater pushing in from the Gulf will dominate the environment, ecosystem of flora and fauna.
- The low velocity will silt up the riverbed soon. The sediment and nutrient load will be dropped in the channel profile.
- Navigation and all port activities will come to a full stop.
Resolution: This is a quick design problem to introduce the history, hydrology, and topography that makes up the boundaries (specifically one boundary) of the City of New Orleans. Each group will speculate on how to build on the expanded levee section at the receding Mississippi River.
Begin by choosing a concept and set of precedents to spark the discussion of how to design on the exposed higher ground. Design proposals ask for interventions in public spaces within the new thickened levee condition along the French Quarter. While groups will likely refer to large scale interventions, the expectation is that within a week’s time only a segment of the site will be resolved with any specificity. Take into account the particular gridded surface of the concrete revetment structure.
- How does the project/installation address and respond to change over time?
- How does the intervention respond to the new increasingly saline environment?
Reading:
Campanella, Richard: Bienville’s Dilemma: A Historical Geography of New Orleans, 2008
ACOE Revetment: www.mvn.usace.army.mil/eng/ci/concrete.asp 2011
McPhee, John The Control of Nature. 1989
US Congress Hearings before the Subcommittee on Flood Control, 1954
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