1. William Locke Bozeman, MT Understanding KATRINA 8/29/05 http://www.nnvl.noaa.gov/hurseas2005/Katrina1215z-050829-4kg12.jpg

2. On promontories, not bays On promontories, not bays 2 category 5s, 7 cat. 4s 2 category 5s, 7 cat. 4s http://www.nhc.noaa.gov/gifs/hur5005.jpg

3. History (1900-1996) http://www.nhc.noaa. gov/pastall.shtml South Florida = most frequent South Florida = most frequent South Texas and Miss. Delta = second South Texas and Miss. Delta = second Katrina Katrina Rita Rita Percent per year probability (historical) per 50-mile (80 km) coastline

4. Hurricane history Cat. 3+ Hurricanes Named storms http://www.nhc.noaa.gov/gifs/atlhist_lowres.gif

5. Hurricane history Cat. 3+ Hurricanes Named storms But – see http://wind.mit.edu/~ emanuel/anthro2.htm http://wind.mit.edu/~ emanuel/anthro2.htm

6. Kerry Emanuels’ Nature discussion Nature discussionNature discussion The Power Dissipation Index is a measure of the energy associated with hurricanes, and is calculated from the velocity cubed times the area affected (size times persistence). The Power Dissipation Index is a measure of the energy associated with hurricanes, and is calculated from the velocity cubed times the area affected (size times persistence). 70% increase since 1974 70% increase since 1974 Note ENSO cyclicity! Note ENSO cyclicity! ftp://texmex.mit.edu/pub/emanuel/PAPER S/NATURE03906.pdf

7. Miss. delta Sea level? Sea level? –Lake Pontchartrain –Lake Borgne –SW Pass http://www.mpcnetwork.com/marinersinfo/charts/gm/2neworleans.gif SW PASS

8. Mississippi delta in flood Note: Note: –Sediment to Gulf 1,000,000 ton/day –Flooded outer delta –Dry diked areas –Vegetation/land use on natural levees http://jan.ucc.nau.edu/~rcb7/MissDelta.jpg Bayou Lafourche

9. Topography of New Orleans Much of north N.O. lies well below sea level Much of north N.O. lies well below sea level Sea water gains access through canals Sea water gains access through canals An uneasy truce is maintained by ~350 miles of levees. An uneasy truce is maintained by ~350 miles of levees. From Brian Hayes (2005), American Scientist, v. 93, p. 496-499 [original map from Louisiana State University]

10. Natural levees Result from multiple floods Result from multiple floods Extend 2+ km from river channel Extend 2+ km from river channel Are poorly engineered! Are poorly engineered!

11. Which way to the ocean? Miss. R. is twice as long (half as steep) as shortcuts via the Atchafalaya R. or Lake P. Miss. R. is twice as long (half as steep) as shortcuts via the Atchafalaya R. or Lake P. http://www.ssec.wisc.edu/~gumley/modis_gallery/images/MississippiDelta_20040127_1940_1000m.jpg Atchafalaya Mississippi

12. Mississippi River deltas Sea level stable for ~6000 yr Sea level stable for ~6000 yr Delta front moves as river avulses Delta front moves as river avulses Average duration <1000 yr Average duration <1000 yr Modern delta for ~1300 yr Modern delta for ~1300 yr Time for a change! Time for a change! http://www.uwgb.edu/dutchs/graphic0/geomorph/missdlt.gif

13. Recent sediment thickness Greatest near edge of shelf [max. ~ 100 m] Greatest near edge of shelf [max. ~ 100 m] Can’t restore wetlands Can’t restore wetlands Can’t armor coast Can’t armor coast Can compact and subside (1-10 mm/yr)! Can compact and subside (1-10 mm/yr)! S.L.  1-3 mm/yr S.L.  1-3 mm/yr N.O. -8’ to 15’ “above” sea level. N.O. -8’ to 15’ “above” sea level. http://coastal.er.usgs.gov/LA-subsidence/figure2.html

14. Levee history & failure Overtopping Overtopping Seepage through/under the levee Seepage through/under the levee Not protection - postponement Not protection - postponement http://web.umr.edu/~rogersda/flood_hazards/Should%20I%20Trust%20That%20Levee.htm Courtesy USACOE

15. Katrina http://www.ssd.noaa.gov/GOES/katrina.html

16. Sea-surface temperatures Note extremely warm water Note extremely warm water Shallow coastal waters commonly lack cold layers Shallow coastal waters commonly lack cold layers Image courtesy NASA-JPL

17. Intensification Warm surface water alone was insufficient Warm surface water alone was insufficient Dynamic water topography shows a deep warm current Dynamic water topography shows a deep warm current (Also briefly strengthened Rita, later) (Also briefly strengthened Rita, later) Scharoo et al., Eos, v. 86 (40), p. 366.

18. Katrina by strength and warnings Tropical depression Tropical depression Tropical storm Tropical storm Hurricane 1 Hurricane 1 Hurricane 2 Hurricane 2 Hurricane 3 Hurricane 3 Hurricane 4 Hurricane 4 Hurricane 5 Hurricane 5 http://www.nhc.noaa.gov/archive/2005/KATRINA_graphics.shtml

19. Katrina winds

20. Katrina modeled rainfall Note max. EAST of track of storm eye Note max. EAST of track of storm eye Same for wind Same for wind

21. Hurricane Structure Cyclonic (CCW) winds >74 mph Cyclonic (CCW) winds >74 mph Right side = storm wind + forward motion Right side = storm wind + forward motion Left side = storm wind – forward motion Left side = storm wind – forward motion N.O. Waveland Biloxi

22. Storm surge Key variables Key variables –Onshore winds –Central pressure –State of the tide –Configuration of the coast Can exceed 8 m (25’) in worst case scenario Can exceed 8 m (25’) in worst case scenario

23. Katrina comes ashore [Surviving] tide gauges [Surviving] tide gauges

24. Katrina storm surge (model hindcast) http://hurricane.lsu.edu/floodprediction/katrina32/images/katrina32.JPG It missed New Orleans It missed New Orleans Max. impact on Miss. Coast Max. impact on Miss. Coast Funneling? Funneling?

25. Flooding at New Orleans Observed at Miss. River gauge Observed at Miss. River gauge Not (quite) to flood stage ~12 foot storm surge Not (quite) to flood stage ~12 foot storm surge Big sigh of relief as storm passed but… Big sigh of relief as storm passed but…

26. http://graphics8.nytimes.com/images/2005/09/20/national/21leveegraphic.jpg

27. Images courtesy NASA

31. http://coastal.er.usgs.gov/hurricanes/katrina/ Biloxi Biloxi Pass Christian Pass Christian Damage (courtesy of USGS)

32. Most intense http://www.nhc.noaa.gov/pastall.shtml RankHurricaneYear Category at landfall Minimum Pres. (mb) Minimum Pres. (in) 1(FL Keys)1935589226.35 2Camille (MS, SE LA, VA)1969590926.84 3Andrew (SE FL, SE LA)1992592227.23 4(Indianola TX )1886492527.31 5(FL Keys, S TX)1919492727.37 6(Lake Okeechobee FL)1928492927.43 7Donna (FL, Eastern U.S.)1960493027.46 8(New Orleans LA)1915493127.49 8Carla (N & Cent. TX)1961493127.49 10LA (Last Island)1856493427.58

33. Costliest http://www.nhc.noaa.gov/pastall.shtml RankHurricaneYearCategoryDamage 1Andrew (SE FL, SE LA)1992526.5 2Charley (SW FL)2004415 3Ivan (AL/NW FL)2004314.2 4Frances (FL)200428.9 5Hugo (SC)198947 6Jeanne (FL)200436.9 7Allison (N TX)2001TS5 8Floyd (Mid-Atl & NE)199924.5 9Isabel (Mid-Atlantic)200323.4 10Fran (NC)199633.2

34. Deadliest (through 1996) http://www.nhc.noaa.gov/pastall.shtml RANKINGHURRICANEYEARCATEGORYDEATHS 1.TX (Galveston)190048000 + 2.FL (Lake Okeechobee)192841836 3.FL (Keys)/S. TX19194600 4.NEW ENGLAND19383600 5.FL (Keys)19355408 6.AUDREY (SW LA/N TX)19574390 7.NE U.S.19443390 8.LA (Grand Isle)19094350 9.LA (New Orleans)19154275 10.TX (Galveston)19154275 11.CAMILLE (MS/LA)19695256

35. Who’s to blame? Individuals who assumed risk, then didn’t listen and follow instructions Individuals who assumed risk, then didn’t listen and follow instructions New Orleans, for not having a real evacuation plan New Orleans, for not having a real evacuation plan The Corps of Engineers, for a century and more of false promises and wasted billions The Corps of Engineers, for a century and more of false promises and wasted billions FEMA et al., for not recognizing the scope of the impending disaster FEMA et al., for not recognizing the scope of the impending disaster Congress, for not funding adequate maintenance/upgrades of levee system Congress, for not funding adequate maintenance/upgrades of levee system

36. What do we do about it? Abandon New Orleans? Abandon New Orleans? Rebuild New Orleans only along the natural levees? Rebuild New Orleans only along the natural levees? Rebuild, but zone/plan undersea areas for only unoccupied ground floors? Rebuild, but zone/plan undersea areas for only unoccupied ground floors? Rebuild and raise the levees? Rebuild and raise the levees? Rebuild Rebuild

37. In summary…