“There are only two kinds of levees, those that have failed and those that will fail.”

Before KatrinaPrevious hurricane damage from less severe

storms1965- Hurricane Betsy put parts of the city

under 8 feet of water1992- Hurricane Andrew missed by 100 miles1998- Hurricane George causes billions of

dollars of damage, but it was not a direct hitDisappearance of barrier islands and

marshes due to construction

Before Katrina: Google Earth

Facts and Figures:“A hurricane storm surge can reach heights of

20 feet, but every 4 miles of marsh can absorb enough water to knock it down by one foot.”

Oil & gas exploration has accounted for 1/3 of the delta’s landloss

Coast provides 1/3 of country’s seafood, 1/5 of its oil, and 1/4 of its natural gas & harbors 40% of the nation’s coastal wetlands and provides wintering grounds for 70% of migrational water fowl

An acre of coastal wetlands disappears every 24 minutes

Fixes:Attempts to restore

marsh ecosystemCoast 2050River system on

critical areas of Mississippi

Levees to allow fresh water to escape and wash out sediments to Gulf

5000 cubic yards of sand transported to restore barrier islands

Millenium Port

Protecting New Orleans1998- $14 billion plan proposed to restore

wetlands rejected by Congress

Record sea surge of Katrina peaked at 28 feetState of the art barriers can only contain a

surge reaching 15 feetPlans for the future will improve the levees of

the city to Category 5 levelsIdeal plans would take 5-10 years to build and

cost $25-35 billion dollars

Possible PlansNot using the Army Corp of Engineers for

contractorsOuter ShieldFloating gatesSluices that slideHydraulic disksRising flaps

Grand PlanThree protection schemes:

Inner ringComprehesive planOuter shield

Delta formationForms a dynamic landscape of wetlands that

have been eroded by human activityBarrier islands evolve but human activities

speed up shrinkageIsland restoration has to be a priority to

protect the delta in the future.

Delta Formation:

After KatrinaScientists and

engineers aren’t the only ones involved in the process- stakeholder engagement

Demonstration project for other coastal regions

Investment for restoration is still being debated

Levee ConstructionArmy Corp of Engineers rebuilds after

Hurricane BetsyHigh Level option- raise all barriers to resist a

Category 3 hurricane (16-18.5 feet above sea level)

Barrier option- construct levees and gates between Lake Brogne and Lake Pontchartrain, and navigation lock, rock dike and flood control structure on Industrial Canal at Lake Pontchartrain

Impact of NEPA court case1976 lawsuit filed by Save Our Wetlands

alleged that Army Corp of Engineers FEIS (Final Environmental Impact Statement) for levee construction is inadequate and WINS.

Corp reevaluates building plan, changing from barrier to high level plan

Would the original plan have saved the city?Probably not. Levees

failed for several reasons:Insufficient depth of

pilingsUnstable underlying

soilsLax maintenance

practices

Would the original plan have saved the city?Storm surge came

from Lake Borgne, not Lake Pontchartrain

Barrier project may have exacerbated the damage by deflecting surge

Would the original plan have saved the city?MRGO

Shrinks from 2000 to 200 feet wide

Intensified storm surge by 20%

Increased velocity of surge from 3 to 6-8 feet per second

Storm Surge modelinghttp://www.nd.edu/~adcirc/katrina.htmThe first detailed computer model of Hurricane

Katrina's storm surge shows a gargantuan, 15-foot dome of water forming in the Gulf of Mexico. Propelled westward by 140-mph winds, the surge slams into levees east of New Orleans and pours over them, flooding a large inhabited area.

Later, the model shows water flooding most of the rest of New Orleans from Lake Pontchartrain through levee breaches. Meanwhile, Katrina's giant wave continues its relentless northeast course, pushing a 30-foot wave over the Biloxi-Gulfport area in Mississippi.