Hurricane Katrina Storm Surge Induced Flooding

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Hurricane Katrina Storm Surge Induced Flooding
and

• Low-Lying New Orleans
• How to Prevent Future Damages

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Introduction

• What is storm surge
• What happened during Hurricane Katrina
• Why New Orleans is vulnerable
• The future of New Orleans

http//www.pbs.org/wgbh/nova/sciencenow/dispatches
/images/050901-katrina2-l.jpg
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What is a Storm Surge?

• Meteorological Residual
• Most dangerous phenomenon associated with
  hurricanes
• Accounts for 70-90 of death damage

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What is Storm Surge?

• Large change in sea level
• Generated by extreme weather conditions
• Mound of water driven toward shore by storm
• Waves on top of surge devastate area
• Water weighs 1000 kg/m3 Immense potentially
  destructive power

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Background

• General Factors Contribute to Storm Surge
• Storm Winds
• Wave Run-Up
• Low Pressure inside the storm
• Astronomical Tides
• Local Factors
• Slope of Continental Shelf
• Shape of Coastline
• Elevation relative to sea level

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Dangers of Surge

• Devastating to low-lying coastal regions
• Bay of Bengal - India
• Galveston Texas
• Inland Surge
• Lake Okeechobee, Florida
• 1928-3m surge Hurricane San Filippe
• 1,836 people killed, massive flooding
• Lake Pontechrain, Louisiana
• 2005 8m Hurricane Katrina
• Death toll-unknown and still rising

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BEFORE
AFTER
http//www.spaceimaging.com/gallery/hurricanes2005
/katrina/NewOrleans/NewOrleans1.jpg
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Before and After
http//chattablogs.com/quintus/new_orleans1.jpg
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• Satellite Images
• After August 30th
• Before August 27th

http//www.nasa.gov/images/content/126535main_newo
rleans_flood_0831.jpg
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What Happened During Katrina?

• Storm Surge
• 8 meters (25-28 feet)
• Water is STRONG!
• Pumping Stations flooded
• Lack of drainage in city
• Left helpless

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What Happened During Katrina?

• Channels/Canals
• Lack of sea gates allowed water to flow deep into
  the city
• Intense pressure from water and winds
• Protective walls broke
• Funneling
• MRGO Intracoastal Waterway
• New Orleans Flood Map
• http//mapper.cctechnol.com/floodmap.php

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Why is New Orleans VulnerableBelow Sea Level

• City averages 6 feet below sea level
• Drainage of former swamp areas led to subsidence
• Located between levees of Lake Pontchartrain and
  Mississippi River
• Creates bowl effect

http//en.wikipedia.org/wiki/ImageNew_Orleans_Lev
ee_System.gif
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New Orleans Elevation
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Why is New Orleans VulnerableDisappearing
Wetlands and Barrier Islands

• Wetlands and Barrier Islands are best natural
  defense against storm surges
• For every mile of continuous wetland the height
  of a storm surge can be reduced 3 to 8 inches
• Wetlands and Barrier Islands are naturally
  replenished with sediment from the flooding
  Mississippi

Before and after Hurricane Katrina
http//news.nationalgeographic.com/news/2005/09/im
ages/050919_katrina_delta.jpg
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Why is New Orleans VulnerableDisappearing
Wetlands and Barrier Islands

• Upriver Dams have reduced sediment in the river
  by up to 67
• Levees built around New Orleans channel the
  rivers flow far out into Gulf of Mexico
• Wetlands and barrier islands being denied natural
  replenishment

http//news.minnesota.publicradio.org/features/200
3/08/14_hetlandc_morupdate/images/gavinspointdam_l
arge.jpg
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Why is New Orleans VulnerableDisappearing
Wetlands and Barrier Islands

• Over the last 50 years wetland loss has been
  about 60 square kilometers per year
• Canal construction has allowed saltwater
  intrusion to freshwater marshes
• Additional salinity kills native plants, which
  causes even more erosion

http//www.whitehouse.gov/omb/budget/fy2005/images
/corps-6.jpg
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The Future of New OrleansRebuilding Current
Structures

• Restore New Orleans to Pre-Katrina before June
  1st
• Official start of hurricane season
• Many building permits already given out

http//ap.lancasteronline.com/5/new_orleans_levees
Work continues, Wednesday, Nov. 30, 2005, at the
17th Street Canal floodwall that was breached
after Hurricane Katrina in New Orleans.
Government engineers performing sonar tests at
the 17th Street Canal found exactly what
independent investigators said they would, that
steel reinforcements barely went more than half
as deep as they were supposed to, a U.S. Army
Corps of Engineers official said Wednesday. (AP
Photo/Cheryl Gerber)
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The Future of New OrleansSea Gates

• Giant air-filled walls
• Across Lake Pontchartrains two inlets
• Considered since 1960s
• Used in Holland Britain
• Cost 500 million-1 billion

The Delta Project - Holland
http//www.alumni.northwestern.edu/travel/holland-
belgium-photos.html?actionviewPhotophotoID11153
12046
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The Future of New OrleansClosing/Covering Canals

• Only keep heavily used canals open
• Cover others (turn into culverts )
• Turn into parks/trails

MRGO
Today, only a slim line of broken marsh lies
between the MRGO and Lake Borgne (top of frame).
http//www.louisianasportsman.com/stories/2003/par
adise-lost/future-of-mrgo.htm
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The Future of New OrleansWetland Rehabilitation

• Dredging of canals
• Saltwater intrusion
• Hand planting is costly

http//www.pbs.org/journeytoplanetearth/images/1la
2.jpg
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The Future of New OrleansBarrier Islands

• First line of protection
• Shrinking rapidly
• Coast 2050

http//www.earthsky.com/humanworld/shows.php?date
20051230
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Coast 2050
http//www.coast2050.gov/barrier_island.htm
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The Future of New OrleansOther Ideas

• Move pumping stations
• Drainage Systems
• Contain Neighborhoods
• Connect barrier Islands
• Netherlands Delta Works
• Lowlands into parks

http//www.globalsecurity.org/military/facility/ne
w-orleans-flooding-pics.htm
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Conclusion

• New Orleans future is unclear
• Will take multiple solutions to protect the
  sinking city
• High cost and will take years to infiltrate

http//www.globalsecurity.org/military/facility/ne
w-orleans-flooding-pics.htm
http//rst.gsfc.nasa.gov/Sect14/Sect14_10a.html
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THANKS!!!
Chris Below Chris Dierich
Keith Erickson Rachel Kjos
http//www.all4all.org/images/2005/09/2065.jpg