14th Riversymposium, keynote presentation from Toine Smits (2011)
14th Riversymposium, keynote presentation from Denise J.Reed (2011)
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Transcript of 14th Riversymposium, keynote presentation from Denise J.Reed (2011)
The Mississippi Flood of 2011:Opportunity for a new approach to
management?
Denise J. ReedPontchartrain Institute for Environmental Sciences
University of New Orleans
Managing the Mississippi RiverManaging the Mississippi River
Outline
• Flooding in coastal Louisiana• The coastal context• Current Mississippi River management
approaches• The flood of 2011• A new approach?
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Coastal Louisiana
New Orleans
Vulnerable from the North and South
New Orleans – the Crescent City
Hurricane Katrina 2005….
Flooding from the River - Impacts the City
Benefits the Coastal Ecosystem
New Orleans
…coastal Louisiana has undergone a net change in land area of about -1,883 square miles (mi2) from 1932 to 2010. This net change in land area amounts to a decrease of about 25 percent of the 1932 land area. … 1985 to 2010 show a wetland loss rate of 16.57 mi2/year.
Couvillion et al. (2011)
What is land loss?Land loss = interior marsh deterioration
Mississippi Delta Plain7000 years of sediment depositionLand loss balanced by land gain
3000-4000 yrs old
< 2000 years old
Projected Coastal Louisiana Trends: 1956-2050LandWater
Land Loss 1956-2000Projected Land Loss 2000-2050
Land Gain 1956-2000Projected Land Gain 2000-2050
1956 – 2000 1525 sq. mi. of coastal landscape lost average rate 35 sq.mi./yr. for 44 years
2000 – 2050 Projected loss - another 513 square miles
What Changed? From natural delta building to massive land loss
Captain A. A. Humphreys
Lieutenant H. L. Abbot
Delta Report
Early River ManagementEarly River Management
The Great Flood of 1927The Great Flood of 1927
• 246+ Deaths• 325,000 Refugees• 162,000 Homes Inundated• 16.6 Million Acres Flooded
1947 Fisk Map of the river’s historic course 1958 River Flood Capacity Diagram
1934 National Resources Planning Board
“In the interests of national welfare there must be maximum control of water resources, from the desert trickle that might make an acre or two productive to the raging flood waters of the Mississippi.”
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River levees stop current sediment load getting to coastal wetlands
Building of new land is severely restricted
2011 Flood
“SHOULD DIVINE PROVIDENCE ever send a flood of the maximum predicted by meteorological and flood experts as a remote probability but not beyond the bounds of ultimate possibility, the floodways provided in the plan are still normally adequate for its passage without having its predicted heights exceed those of the strengthened levees.”
Edgar Jadwin, Major General, Chief of Engineers, December 1, 1927
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Managing the Flood in Louisiana 27
Bonnet Carre Spillway - ~ 1 yr in 10
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Bonnet Carre An effective flood relief valveNo land building…..
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Flooded Areas
1927 Flood vs
2011 Flood
1927 Flood = 16.8M acres2011 Flood = 6.35M acres
Flood of 2011
• Operation of structures not seen in > a generation
• Routing of floodwaters into lakes and bays• Effective management of water• Sediment management = dredging• Delta plain largely isolated from flood water
and sediment
National Water Commission, 1973
“federal water planning today is now oriented toward construction of water resources projects, an orientation that made sense 50 years ago but that does not relate to today’s water problems”
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Achieving Sustainability
Stop wasting sediment!
A New Approach to River Management for the 21st Century
Managing the Mississippi RiverManaging the Mississippi River
Exports
Energy security
Markets
Flood Protection
NavigationOil and Gas
Imports
Irrigation
Water supplyNutrients
Industry
Agriculture
The Old Way…
Water resources projects are selected on the basis that …“the benefits to whomsoever they may accrue are in excess of the costs and the lives and social security of the people will be otherwise affected” Congress of the US to Corps of Engineers, 1936
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A New WayEconomy, Society AND Environment
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Managing a Flood to Maximize Land Building?
Wax Lake Delta
Managing the Lower Mississippi
• An integrated approach to management is essential in the Lower Mississippi River.
• The present system of levees, structures and navigation features was developed almost a century ago and now results in conflicts among potential uses of the river resource.
• Realistic multi-use management approaches are urgently needed
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A Vision for Lower Mississippi River Management
Management that coordinates and guides the use of the river resources to:
• increase the reliability of marine transportation, • reduce the risk of flooding due to seasonal high
water, and • provide for the distribution of sediment and
water to sustain the coastal ecosystem.
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Additional Benefits
Such management supports • the economy of the region and the nation, • provides for a plentiful supply of clean water
for municipalities and industries adjacent to the Lower River,
• improves the health of the northern Gulf, and • affords world class recreational opportunities.
A New Approach to Flood Management for the 21st Century