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?

3

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.”

18

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

23

24

25

26

Managing the Flood in Louisiana 27

Bonnet Carre Spillway - ~ 1 yr in 10

28

Bonnet Carre An effective flood relief valveNo land building…..

29

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”

31

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

38

A New WayEconomy, Society AND Environment

40

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

41

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.

42

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