Hurricane Isaac's legacy: wetland destruction, and a test of the New Orleans levees

By: Dr. Jeff Masters , 5:05 PM GMT on January 07, 2013

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The hurricane season of 2012 will rightfully be remembered for the legacy left behind by Hurricane Sandy. But in Louisiana, the other hurricane to affect the U.S. in 2012--Hurricane Isaac--left a legacy of its own. Isaac hit Louisiana as a Category 1 hurricane with 80 mph winds on August 28, but the storm's massive wind field brought a storm surge characteristic of a Category 2 hurricane to the coast. A storm surge of 11.1 feet was measured at Shell Beach, LA and higher surges were reported in portions of Louisiana. The surge levels experienced along portions of the New Orleans levee system were similar in magnitude to the surge of Hurricane Katrina in 2005. Fortunately, the new $14.5 billion upgrade to the New Orleans levee system kept the city dry, and we can now be confident that the city will stay protected from Category 2-level storm surges. The new levee system has yet to be tested against a full Category 3-level storm surge, the maximum it is designed to handle.


Figure 1. Hurricane Isaac lit up by moonlight as it spins towards the city of New Orleans, LA, on August 26, 2012. The Suomi National Polar-orbiting Partnership (NPP) satellite captured these images with its Visible Infrared Imaging Radiometer Suite (VIIRS). The "day-night band" of VIIRS detects light in a range of wavelengths from green to near-infrared and uses light intensification to enable the detection of dim signals. Image Credit: NASA/NOAA, Earth Observatory.

Environmental impacts of Isaac
One major long-term environmental impact of Isaac will be the erosion and destruction of wetlands along the Southern Louisiana coast. A 2011 study by the USGS found that four hurricanes in the past seven years--Katrina, Rita, Gustav, and Ike--have together destroyed about 250 square miles of Louisiana marshland--an area 20% the size of Rhode Island. Researchers have yet to quantify how great Isaac's impact was on Louisiana's wetlands, but given Isaac's large size, large storm surge, and the extended battering it gave the coast, I expect 2012 will be one of the state's highest years on record for wetland loss. Over the past 25 years, Louisiana has lost an average of 17 square miles per year of wetlands, and I expect Louisiana lost 30 - 70 square miles of wetlands in 2012, primarily due to Isaac. As I explain in my detailed article on Storm Surge Reduction by Wetlands, wetlands can help significantly reduce the storm surge from a hurricane, though the degree of protection wetlands provide from storm surges is extremely complicated and is largely unknown. The general rule of thumb is that each 2.7 miles of marsh reduces the storm surge by one foot, though wetlands will provide almost no protection from a slow-moving storm like Isaac, which had enough time to completely inundate the coast, despite the presence of wetlands. Louisiana's wetlands have other huge benefits besides hurricane protection, though--they filter out nutrients that would contribute to the huge Gulf of Mexico dead zone, they support 25% of the nation's total commercial fishing haul, and provide storm protection to five of the nation's largest ports.


Figure 2. Hurricane Isaac inundated large areas of Southeastern Louisiana due to storm surge levels in excess of 10'. Image credit: USGS.

One way in which Isaac may have helped the marshlands of Louisiana and Mississippi, though, is that the storm drowned tens of thousands of Nutria, the large semi-aquatic South American rodents released in Louisiana and Mississippi in the 1930s by fur trappers looking for new stock. Nutria can severely reduce overall wetland biomass, and lead to the conversion of wetland to open water. Populations were kept in check as long as fur prices were high, but a fur price collapse in the 1980s led to a nutria population explosion into the millions. The Louisiana Department of Wildlife and Fisheries emphasizes that without effective, sustainable nutria population control, coastal wetland restoration projects will be greatly hindered. The Louisiana's 2012 Coastal Master Plan, unanimously approved by the Louisiana State Legislature in May 2012, called for 109 projects costing $50 billion over 50 years to use a combination of restoration, nonstructural, and targeted structural measures to provide increased flood protection. Louisiana needs to build a series of engineered structures called diversions along the lower Mississippi River in order to restore river sediment to Louisiana's marshlands, said a report co-authored by 22 prominent scientists and engineers in April 2012.

Jeff Masters

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Member Since: August 6, 2011 Posts: 4 Comments: 44499
good evening aussie..have no idea what Time it is there..but..its just awful the temps and the fires around you, stay safe my friend,with all those fires the air you breathe will probably be bad as well when the wind is right...thanks for all the pics etc..
Member Since: August 6, 2011 Posts: 4 Comments: 44499
Quoting Doppler22:
Wow.... I hope Australia gets some rain soon... they really need it

Unfortunately, there is nothing really coming, just a few passing light showers.
Quoting indianrivguy:
Morning folks!
Evening Aussie.. wow, y'all are being fried alive down there. I thought it was wonderful you offered your help yesterday to your mate Aussie, you are a good egg sir.

That's what humans should always do, help out there friends neighbours and countrymen/woman no matter when. If we all did that the world would be a better place. We need to bring back mate-ship.
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wow..a rain maker for sure..............
Member Since: August 6, 2011 Posts: 4 Comments: 44499
Member Since: August 6, 2011 Posts: 4 Comments: 44499
heed your local warnings texas tonight-tomorrow...
Member Since: August 6, 2011 Posts: 4 Comments: 44499
Good Morning Folks..7-day for tampa bay..warm this week..
Member Since: August 6, 2011 Posts: 4 Comments: 44499
Wow.... I hope Australia gets some rain soon... they really need it
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Morning folks!
Evening Aussie.. wow, y'all are being fried alive down there. I thought it was wonderful you offered your help yesterday to your mate Aussie, you are a good egg sir.
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x
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Quoting HadesGodWyvern:
At 2:00 PM CST, Tropical Cyclone Narelle (995 hPa) was located near 11.9S 118.4E or 790 km north northwest of Broome has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 9 knots.

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What is the GFS hinting at here????


Temps in C
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255. HadesGodWyvern (Mod)
At 2:00 PM CST, Tropical Cyclone Narelle (995 hPa) was located near 11.9S 118.4E or 790 km north northwest of Broome has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 9 knots.

Gale Force Winds
================
100 NM from the center

Dvorak Intensity: T3.0/3.0/D1.0/24 HRS

Forecast and Intensity
=======================
12 HRS: 12.1S 117.1E - 45 knots (CAT 1/Tropical Cyclone)
24 HRS: 12.7S 116.4E - 55 knots (CAT 2/Tropical Cyclone)
48 HRS: 15.0S 115.7E - 80 knots (CAT 3/Severe Tropical Cyclone)
72 HRS: 17.5S 114.0E - 100 knots (CAT 4/Severe Tropical Cyclone)

Additional Information
======================
Position based on 0432 UTC infrared and visible satellite image animation. Curvature of convective bands has improved, giving a 0.75 wrap. Exposed low level cloud lines evident on eastern flank of CDO indicate system is still affected by weak shear. Dvorak analysis DT=3.0 based on curved band, MET=PAT=3.0. FT based on DT. Northeast vertical wind shear is reducing as the system becomes more organized.

The environment is favourable for further development with deep moisture, upper divergence and a vigorous westerly monsoonal flow to the north. Intensification is expected at the standard rate for 72 hours, reaching category 4 off the northwest coast of Western Australia, before weakening in the longer term as the system moves over cooler waters.
Member Since: May 24, 2006 Posts: 54 Comments: 48539
Australia is HOT damn HOT!!!!



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Link
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It's now raining and snowing in parts of Tasmania. Thanks you Mother Nature.
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NSW is ablaze.




Google Crisis map
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Member Since: August 13, 2009 Posts: 13 Comments: 6925
Ryan Maue ‏@RyanMaue
After week 1 of intense heat, GFS expands & goes for more in week 2 for southern Australia. 120-125°F.

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Sydney, NSW: 41.8°C feels like: 40.0°C, RH: 15% Wind: NW 25.9km/h Updated: 03:29 PM Forecast: 21–43°C
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Quoting trHUrrIXC5MMX:


Knowing how things are there I'll rather stick my cold...


+1, you can always dress more warmly.

I am beginning to think that the rest of January will stay relatively mild for the Southeast US overall with only one significant cold spell that will NOT bring freezing temps to my area. The long range models are not showing anything that impressive in terms of an arctic air mass moving really far south.
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Quoting ktymisty:


whew...105.1F at 3.40pm.
Still slightly cloudy so that's good :)

Some little F***s deliberately lit a fire in the bush behind Shelvey/Bidwill a suburb in western Sydney. Were seen riding away by the residents. That fire injured 2 fire fighters that were attending to try and put that fire out. Thankfully that fire has now been contained.
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ABC News now Geo-block free.
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Quoting AussieStorm:

not as bad as 105.4F


Larger image.


whew...105.1F at 3.40pm.
Still slightly cloudy so that's good :)
Member Since: August 22, 2007 Posts: 0 Comments: 207
Member Since: August 13, 2009 Posts: 13 Comments: 6925
Quoting AussieStorm:

I feel for you buddy. LOL
Give me hot weather over cold weather anytime.


Knowing how things are there I'll rather stick my cold...
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Member Since: July 15, 2006 Posts: 183 Comments: 57276
Member Since: July 15, 2006 Posts: 183 Comments: 57276
Member Since: July 15, 2006 Posts: 183 Comments: 57276
The NHC released their Tropical Cyclone Reports (TCRs) on Debby, Kirk, Carlotta, and Olivia today. Changes include a peak intensity of 55 kt for Debby (it was 50 kt operationally), and a 95 kt peak intensity for Carlotta (up from the operational 90 kt). There have been no changes to Kirk or Olivia as far as I can tell.

Debby

Kirk

Carlotta

Olivia
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NSWRural Fire Services statewide update: 124 fires, 340 trucks, 1126 Firefighters, 63 Aircraft.
53989.59 ha(208.455sq Miles) burnt.
0 lives lost
0 Properties lost
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According to Eric Holthaus, fewer people evacuated in Hurricane Sandy than Hurricane Irene.
Member Since: July 6, 2010 Posts: 113 Comments: 33461
About that other kind of flood risk...

Preliminary Flood Maps in Orange County, Texas Ready for Public View


Main Content
Release date:
January 7, 2013
Release Number:
R6-13-005

Public Open Houses Scheduled to Share Map Changes and Flood Risk Information

DENTON, Texas –Homeowners, renters and business owners in Orange County, Texas are encouraged to look over newly released preliminary flood maps in order to determine their flood risks and make informed decisions.

Orange County officials and the Federal Emergency Management Agency (FEMA) are presenting the preliminary maps to communities and unincorporated areas in order to help leaders and residents identify known flood risks and use that information to make decisions about buying flood insurance and how the community should move forward with any development.

The Texas-based coastal flood mapping effort follows the release of a new, comprehensive storm surge study from the U.S. Army Corps of Engineers (USACE) that gives updated information on coastal flood risks. To share that data, two public workshops have been scheduled in the county where interested citizens can obtain more information about the proposed changes.

Tuesday and Wednesday, Jan. 15 & 16, 2013

Bridge City Community Center

105 Parkside

Bridge City, TX 77611

2 p.m. – 8 p.m.

Jefferson County

Thursday, Jan. 17, 2013

Ford Park Exhibit Hall

5115 I-10 South

Beaumont, TX 77705

2 p.m. – 8 p.m.

“As we work together with our state and local partners to bring this critical information to the county, we ask that everyone review the maps to understand what flood risks are involved,” said FEMA R6 acting Regional Administrator Tony Robinson. “The role of the community as an active partner in the flood mapping process is very important.”

Additional information is available, including links to the interactive mapping website on www.txchart.com. Residents can also contact the Jefferson County Floodplain Administrator for more details. Or the Orange County Floodplain Administrator for more details.
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Quoting RitaEvac:

I hope this pans out. I am seriously ready to drown some gophers or at least flush them out to where the dogs can catch them.
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000
FXUS64 KHGX 080250
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
850 PM CST MON JAN 7 2013

.UPDATE...
UPDATED GRAPHICASTS WITH THIS AFTERNOON`S MM BRIEFING OUT ON OUR
WEB PAGE COMMUNICATING LATE TUESDAY THROUGH WEDNESDAY`S SEVERE
WEATHER THREAT(S). THIS EVENING`S LOWERING PRESSURES OVER CHIHUAHUA
MEXICO IS THE BEGINNING OF WHAT WILL BE A VERY ACTIVE COUPLE OF
MID-WEEK DAYS ACROSS SOUTHEASTERN TEXAS. THIS VERY ADVERTISED EVENT
IS STILL FORECAST TO COME TO FRUITION BEGINNING TOMORROW AS A WARM
FRONT SLIDES UP FROM THE COASTAL BEND. A VERY MOISTURE-RICH AIR
MASS WILL ENVELOP THE REGION FROM LATE TUESDAY THROUGH WEDNESDAY
THAT...IN TANDEM WITH DECENT LOW LEVEL SHEAR...WILL PROVIDE THE
(THERMO)DYNAMICS FOR A HEAVY RAIN AND POSSIBLE WIND/TORNADO SITUATION.
THERE HAS BEEN CONSISTENT RUN-TO-RUN GOOD TURNING (BACKING) OF THE
LOWER 3KM WINDS LEADING TO HIGHER HELICITIES ALONG THE WARM FRONTAL
BOUNDARY TOMORROW. THIS INDICATES A MODEST POTENTIAL FOR EITHER
STRONG CELLS DISPLAYING ROTATING UPDRAFT STRUCTURE...COULD LEAD
TO SUPERCELL ACTIVITY WITH A ISOLATED TORNADO MENTION. THE MAIN
THREAT STILL REMAINS HIGH RAINFALL LEADING TO FLOODING. THE
CURRENT FLOOD WATCH WILL LIKELY BE UPGRADED TO A WARNING AS WE
FALL WITHIN THE 24 HOUR WINDOW OF THIS THREAT. TRAINING
CELLS...EITHER IN THE WARM AIR ADVECTION SCHEME TOMORROW OR AHEAD
OF THE EVENTUAL COLD FRONTAL PASSAGE WEDNESDAY...WILL CREATE
AVERAGE AREAWIDE 3 TO 5 INCHES (WITH LOCALLY 5 TO 7 INCH AMOUNTS
NOT OUT OF THE QUESTION). DARK HOUR SEVERE WEATHER TUESDAY NIGHT
INTO WEDNESDAY MORNING ONLY HEIGHTENS THE NEED FOR STRESSING THIS
FLOODING THREAT. 31
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Member Since: July 6, 2010 Posts: 113 Comments: 33461
The American Meteorological Society 2013 meeting is trending on Twitter.

Norcross: In all my career, I've never seen a situation like when Mayor Bloomberg spoke that Saturday. #Sandy #ams2013

Norcross: I've never felt the sinking feeling than I did when I heard Major Bloomberg speak. He's the trusted voice in NYC. #AMS2013

Norcross: We manually overrode the computer, called #Sandy a "Superstorm" rather than "Post-Tropical Cyclone" #ams2013

Knabb: We were afraid our warning systems would "break" if we issued Hurr warnings for #Sandy" #ams2013

Shapiro: Subtropical wave says "Gotcha you can't escape." Sandy says "I can push back" Polar jet says, "I can sneak around you!" #AMS2013

and on and on..
Member Since: July 6, 2010 Posts: 113 Comments: 33461
Quoting Bielle:


Wow! I think 82 is awful!

not as bad as 105.4F


Larger image.
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Quoting Xandra:
DUNALLEY FAMILY SHARES AMAZING STORY OF SURVIVING TASMANIA'S BUSHFIRE.



Fascinating story! Thanks for the post.
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DUNALLEY FAMILY SHARES AMAZING STORY OF SURVIVING TASMANIA'S BUSHFIRE.

Member Since: November 22, 2010 Posts: 0 Comments: 1426
Quoting AussieStorm:
I just stuck my head out my back door. OH MY GOSH it's so HOT!!!!!!!!!!

81°F inside 102.9°F outside.


Wow! I think 82 is awful!
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SYDNEY'S temperature has hit 40C, as the state battles heatwave conditions.

Official records at the Bureau of Meteorology headquarters had the mercury at 40.4C at 1.05pm today.

Sydney Airport is also above 40C now, up at 40.8C.

Winds are expected to pick up from the west to 40km/h, increasing the temperature by a few more degrees by 4pm.

Penrith became the first Sydney suburb to hit 40C at 12.30pm this afternoon.

Sydney CBD is close to hitting 40C as well, with temperatures at 12.30pm recorded at 38C at Observatory Hill.

Richmond, Bankstown and Sydney Olympic Park were at 38.7C at the same time this afternoon.

Experts are predicting the temperatures to rise even higher over the next three hours.

Link
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Two separate, fast-moving fires are threatening properties in the state's south.
Predictions the state would experience the worst bushfire conditions ever are proving correct.
Wind gusts are hitting 70kph and the temperatures are in the high 30s.
In the Bega Valley, an out-of-control grassfire is threatening homes near Warrigal Range Rd at Brogo.
Near Cooma, a fast-moving fire is expected to hit the Kybean Valley within the next three hours.
Residents in the Numeralla and Carlaminda areas have been told it is too late to leave.
'Watch and act' alerts are in place for fires at Deniliquin, Bland, Harden and Wagga Wagga.
More than 100 fires are burning across the state.
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Quoting trHUrrIXC5MMX:
cold night here.

I feel for you buddy. LOL
Give me hot weather over cold weather anytime.
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Quoting AussieStorm:

If you need any help, let me know and I'll come right up. I'm about an hour away.


Thanks Aussie, will do!
Member Since: August 22, 2007 Posts: 0 Comments: 207
cold night here.
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Quoting GeoffreyWPB:


I feel for you buddy. That is awful.

Thanks
We haven't hit our top temp yet. I just put my hand held wx station under the outdoor table. I'll check it in about 10min, i put it out about 20mins ago.
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Photo just in from the Rural Fire Service of the fire near Yarrabin, which is 12km East of Cooma, where my parents live.

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Quoting AussieStorm:
I just stuck my head out my back door. OH MY GOSH it's so HOT!!!!!!!!!!

81°F inside 102.9°F outside.


I feel for you buddy. That is awful.
Member Since: September 10, 2007 Posts: 0 Comments: 11619

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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