U.S. vulnerability to sea level rise

By: Dr. Jeff Masters , 4:04 PM GMT on June 23, 2009

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In the last century, sea level rose 5 - 6 inches (13 - 15 cm) more than the global average of 7 inches (18 cm) along the U.S. Mid-Atlantic and Gulf Coasts, because coastal lands there are sinking. Over 50% of the U.S. coastline is vulnerable or highly vulnerable to sea level rise, according to the Coastal Vulnerability Index (CVI) developed by the United States Geological Survey (USGS). In the U.S., relative sea level rise (the combined effects of global sea level rise plus the fact the land is sinking) is highest along the Mississippi River Delta in Louisiana, where relative sea level rises of 3.2 ft (.98 meters) have been observed during the 20th century. This is one of the highest relative sea level rises in the world. According to the NOAA Tides and Currents sea level rise interactive tool, the U.S. tide gauges that have shown the highest rates of sea level rise over the past century are at Grand Island, LA (1.8 ft rise since 1947), Galveston, TX (1.1 ft since 1957), and Chesapeake Bay, VA (0.6 feet since 1975). Alaska and some areas along the Pacific Northwest coast are at low risk of sea level rise, because the relative sea level is actually falling at present. Land in these regions is rising as it recovers from removal of the weight of the great ice sheets that covered much of North America during the last Ice Age. For example, relative sea level at Kodiak Island, Alaska has fallen by 1.1 feet since 1975, despite the fact global sea level has been increasing.


Figure 1. Twentieth century annual relative sea-level rise rates in mm/year along the U.S. coast. The higher rates for Louisiana (9.85 millimeters [mm] per year, about 3.3 ft/century) and the mid-Atlantic region (1.75 to 4.42 mm per year, 0.6 - 1.4 ft/century) are due to land subsidence. Sea level is stable or dropping relative to the land in the Pacific Northwest, as indicated by the negative values, where the land is tectonically active or rebounding upward in response to the melting of ice sheets since the last Ice Age. Image credit: Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region (data from Zervas, 2001).

U.S. Coastal Vulnerability
The Coastal Vulnerability Index (CVI) takes into account six factors:

1) The geology of the coast. Barrier islands, river deltas, and marshes are the most vulnerable to erosion and sea level rise, while steep, rocky cliff shores are the least. Sheltered bays like Galveston Bay and Tampa Bay are less vulnerable than the exposed coasts. (Note, however, that hurricane storm surges are typically higher in sheltered bays, at least for slow-moving storms).

2) How steep the land near the coast is. Gently sloping lands are the most vulnerable. In the Gulf Coast region, the slope variable has the highest risk ranking along the Louisiana coast, the Texas coast north of Corpus Christi, and the southwest Florida coast.

3) The local rate of sea level rise. The sea level is rising faster along the western Gulf of Mexico than the eastern Gulf. The highest rates of sea-level rise in the Gulf of Mexico (and in the United States) are in the Mississippi delta region (10 mm/yr, or 1 inch/2.5 years).

4) The amount of shoreline erosion going on. Most of the U.S. coast is moderately or severely eroding, and very few areas are gaining (Figure 2).

5) The mean tidal range. Shores that have a large difference between low and high tide are less likely to get a significant storm tide--the height above mean sea level of the sum of the storm surge plus the tide. For example, in a region like Maine, which has a 12 ft range between low and high tide, a storm having a 9 ft storm surge will have a storm tide below local high tide for a quarter of a tidal cycle. Shores with a very narrow tidal range (e.g., the 2 ft tidal range common along the Texas and Louisiana Gulf Coast) will get a storm tide of 8 - 10 feet with the 9 ft storm surge in the above example. Shorelines with a narrow tidal range always get high storm tides regardless of when the storm surge hits.

6) How high the waves at shore are. Obviously, shores that experience higher wave heights are at greater risk. In the Gulf of Mexico, wave energy is highest along sections of the Texas coast and on the southern tip of the Mississippi delta.

Figure 2. Shoreline change around the United States based on surveys over the past century. All 30 coastal states are experiencing overall erosion due to natural processes (e.g., storms, sea-level rise) and human activity. If the shoreline is uncolored, no data was available. Image credit: USGS, 1985, and taken from Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region).

The Coastal Vulnerability Index (CVI) web page gives detailed maps of each section of the U.S. coast, along with specific reasons why each portion of the coast was assigned the ranking it got. A brief summary:

The Gulf Coast
The Gulf Coast has 55% of its length in the "very high" or "high" vulnerability range. Fully 41% of the coast falls in the "very high" range, far more than the 28% in that category along the Pacific coast and 23% along the Atlantic coast. The region around New Orleans is the most vulnerable region of the entire U.S. coast. The Florida Panhandle, as well as the West Florida coast, are at low to moderate risk because the land is not sinking much, wave heights are lower, and the slope of the land is relatively steep near the coast. The Texas coast is considered to be at a high to very high risk because of the relatively high mean wave height, sinking land, and shallow coastal slope.

The East Coast
The East Coast has 50% of its length in the "very high" or "high" vulnerability range. The highest vulnerability areas are typically high-energy coastlines where the regional coastal slope is low and where the major landform type is a barrier island. A significant exception to this is found in the lower Chesapeake Bay. Here, the low coastal slope, vulnerable landform type (salt marsh) and high rate of relative sea-level rise combine for a high CVI value. The coastline of northern New England, particularly Maine, shows a relatively low vulnerability to future sea-level rise. This is primarily due to the steep coastal slopes and rocky shoreline characteristic of the region, as well as the large tidal range.

The Pacific Coast
The Pacific Coast has 50% of its length in the "very high" or "high" vulnerability range. Areas of very high vulnerability include the San Francisco - Monterey Bay coast and in southern California from San Luis Obispo to San Diego, where the coast is most highly populated. The highest vulnerability areas are typically lower-lying beach areas. The low risk, least vulnerable areas generally occur at rocky headlands along cliffed coasts where the coastal slope is steep, relative sea-level is falling, tide range is large, and wave energy is lower. Examples of these areas are the northern coast of Washington, Monterey, and Cape Mendocino, California.


Figure 3. The Coast Vulnerability Index (CVI) for the U.S.

References
Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region.

National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast (USGS, 2000).

Jeff Masters

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Quoting extreme236:


Just to let you know, if people quote it they can see what it is lol


Lol how the heck are you supposed to find an image url without the name in it anyway......probably would've been better had you not informed everyone about that lol. [edit] I'll upload the image to a hosting site next time.

Anyway Geoffrey got it right first and stormchaser2007 also got it....Hurricane Iris in 2001
Member Since: November 24, 2005 Posts: 635 Comments: 26562
Quoting Ossqss:



Spec's please......

I just got a Verizon enV Touch. Its like an iPhone, but with a better network. (ask me in WUmail if you want more info.. no need to clutter the blog)
Member Since: August 3, 2008 Posts: 16 Comments: 5875
Quoting AussieStorm:

Dean


Close.

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Quoting Levi32:
Well while everyone's bored and I know H2009 likes hurricane trivia I thought I'd try one question lol. I, personally being bad at hurricane history, don't even know if this is a good question or not.

The question is: Name this retired major hurricane that devastated Belize causing over 165 million dollars in damage (2006 USD)





its Hurricane_Iris


i may want to put that in a link or it may give it a way when you Quote
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Quoting Levi32:
Well while everyone's bored and I know H2009 likes hurricane trivia I thought I'd try one question lol. I, personally being bad at hurricane history, don't even know if this is a good question or not.

The question is: Name this retired major hurricane that devastated Belize causing over 165 million dollars in damage (2006 USD)



Just to let you know, if people quote it they can see what it is lol
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Quoting Levi32:
Well while everyone's bored and I know H2009 likes hurricane trivia I thought I'd try one question lol. I, personally being bad at hurricane history, don't even know if this is a good question or not.

The question is: Name this retired major hurricane that devastated Belize causing over 165 million dollars in damage (2006 USD)


Hurricane Dean (Cat 5) was the strongest tropical cyclone of the 2007 Atlantic hurricane season
Hurricane Iris was a Category 4 hurricane that devastated Belize in October 2001
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Quoting Levi32:
Well while everyone's bored and I know H2009 likes hurricane trivia I thought I'd try one question lol. I, personally being bad at hurricane history, don't even know if this is a good question or not.

The question is: Name this retired major hurricane that devastated Belize causing over 165 million dollars in damage (2006 USD)



The location screams Mitch, but the size is throwing me off. Ill say Iris?
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I want some releif here also. I keep seeing heat lightning here.
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Quoting presslord:
Taz....not a lot shakin'... I suspect if we keep it clean and civil, they'll cut us some slack...



i see
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I'll guess Iris
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408- Hello
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Quoting jeffs713:
i want some rain....

and in other news, im posting this from my cell phone. whee!

(and hi mishy!)



Spec's please......
Member Since: June 12, 2005 Posts: 6 Comments: 8185
Well while everyone's bored and I know H2009 likes hurricane trivia I thought I'd try one question lol. I, personally being bad at hurricane history, don't even know if this is a good question or not.

The question is: Name this retired major hurricane that devastated Belize causing over 165 million dollars in damage (2006 USD)

Member Since: November 24, 2005 Posts: 635 Comments: 26562
Quoting hurricane2009:


July 10th is on average the date of the 1st named storm of the season. All of Gators' posts for the last few days has included July 10th, kind of like a subliminal message.
Ahhh ok, thanks for answering my question.
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1964 - In Jacksonville for back to back retired storms Cleo & Dora. Hilda, also retired, hit LA that year.
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Quoting RMM34667:
AWSOME thunderstorm just moving out of south western pasco co FL. Lots of lightening, which didn't show up on radar even after changing the setting. looking forward to the TDWR stations to come back online.

Air has cooled tremondously and I don't have a rain guage, but based on the pool I'd say we got at least 3/4 of an inch.

Very Welcome relief, even if it is short lived.
i want some rain....

and in other news, im posting this from my cell phone. whee!

(and hi mishy!)
Member Since: August 3, 2008 Posts: 16 Comments: 5875
Taz....not a lot shakin'... I suspect if we keep it clean and civil, they'll cut us some slack...
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405. BtnTx
Quoting TampaMishy:
Whats with the July 10 thing? I keep seeing it posted.

I want to know also ???
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My Next Hurricane Eye was 20 years Later,in Hurricane ELENA.

Long Beach ,Miss 1985
Backside eyewall approaching

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At ease tonight press.
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AWSOME thunderstorm just moving out of south western pasco co FL. Lots of lightening, which didn't show up on radar even after changing the setting. looking forward to the TDWR stations to come back online.

Air has cooled tremondously and I don't have a rain guage, but based on the pool I'd say we got at least 3/4 of an inch.

Very Welcome relief, even if it is short lived.
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Whats with the July 10 thing? I keep seeing it posted.
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LOL you no we can all get ban for being off topic
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Best sleeping weather..some rain and thunder!
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Quoting presslord:
done taz...gonna throw up now...




LOL
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done taz...gonna throw up now...
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Well, we have been under a severe thunderstorm watch since about 9am... It still hasnt rained.

I wouldnt mind a nice little storm. Helps to sleep.
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1960s Retired Atlantic Canes
Donna • Carla • Hattie • Flora • Cleo • Dora • Hilda • Betsy • Inez • Beulah • Camille
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Quoting WeatherStudent:


It's winter right now down there, Aussie?

Yes
its 12pm(midday) and its 13.5C (56.3F) atm
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Quoting presslord:
OK...

Who's in charge around here?

And...

What are my orders?



stan on your head and spin it 3 times



just kinding
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Betsy from a Early Earth Orbiting Satellite..in 1965.
My First Hurricane.


I was 5.5 yrs young.

*

[edit] Meteorological history
Storm path

Betsy formed east of the Windward Islands, and moved north through the island chain as a tropical storm, at one point making a complete loop. When it was about 350 miles (560 km) east of Daytona Beach, Florida, and seemed to be on its way to hit the Carolinas, it turned back toward the southwest (making a second complete loop), passing over the Bahamas where winds on Great Abaco Island reached 147 mph (237 km/h). Betsy traveled just north of Nassau, the biggest city in the Bahamas, where it stalled for about three hours, allowing its winds to pound the city.

On September 7, Betsy continued moving toward the southwest toward extreme southern Florida. It passed over Key Largo at the eastern end of the Florida Keys on September 8, and then continued west along the Keys, as a Category 3 hurricane. Hurricane-force winds were experienced in the Miami area for roughly twelve hours. At its landfall on Key Largo, Betsy had an exceptionally large eye (40 miles (65 km) in diameter).

After crossing Florida Bay and entering the Gulf of Mexico, Betsy restrengthened, growing into a Category 4 storm with winds up to 155 mph (250 km/h), only one mile per hour short of qualifying for Category 5 status. It continued northwestward, moving into Barataria Bay on the evening of September 9. It made its second U.S. landfall at Grand Isle, Louisiana, just west of the mouth of the Mississippi River, where it destroyed almost every building. At the time of landfall in Louisiana, Betsy was a strong Category 3 storm.[1] The storm travelled upriver, causing the Mississippi at New Orleans to rise by 10 feet (3 m).

Preparations


A view from the interior of Hurricane Betsy's eye, taken by Hurricane Hunters near the Bahamas, prior to its Florida landfall.

The Baton Rouge weather bureau warned residents to get extra food that would not have to be cooked, or with little preparation. They also warned residents to store a water supply, have flashlights or other emergency light sources, and keep them at the ready. In addition, residents were told to fill the gasoline tanks of their cars, and check to make sure their battery powered radios had full charged batteries in them, and to secure any small boats immediately.[2]

[edit] Impact

Betsy was one of the most intense, deadly, and costly storms to make landfall in the United States. The storm killed 76 people in Louisiana. Betsy caused $1.42 billion in damage, which when adjusted for inflation amounts to $10-12 billion (2005 USD). Betsy was the first hurricane to cause damage in excess of $1 billion (based on damage at the time of the storm%u2014many storms before then have inflation-adjusted damage over $1 billion); the storm thus earned the nickname "Billion-Dollar Betsy".



Aerial view of flooding in New Orleans.
Flooding in the Lower 9th Ward of New Orleans after Betsy


Eight offshore oil platforms were destroyed during Betsy, with others experiencing damage. A Shell oil platform off the Mouth of the Mississippi river was not seen again. The oil rig Maverick, owned by future president George H. W. Bush's Zapata corporation also disappeared during the cyclone. It was insured by Lloyd's of London for US$5.7 million (1965 dollars).[3]
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Quoting potteryX:
Aussie, post 353.
OOoops, sorry, I did not see them then.

it's cool... and i'm freezing cold..... anyone wanna do a house swap?
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While other areas are getting millions in infrastructure to protect them from flooding, the St. Johns River Water Management (or lack thereof) District has a plan to protect the middle river cities from flooding (NOT!).

We just have to "Understand"

"Discharges from Canal 54
have little impact on water
levels in the Middle
St. Johns River Basin
."

During Fay, C-54 discharge nearly equaled the river flow at Sanford.

"In the historic and unprecedented 2004 hurricane season, nearly 4 feet of
rain fell on east-central Florida during a 60-day period. The rainfall statistics
were phenomenal — a series of storms that would only be expected once
every 200 years
."

It happened also in 1993, and again in 2007.

"Both water levels and frustration levels were especially high in the Middle St. Johns River Basin (Lake Harney north to Lake George, including lakes Jesup and Monroe), and as the river overran its
banks, some called for the St. Johns River Water Management District to provide flood relief by releasing water from the St. Johns River to the Indian River through C-54, located about 120 miles to the south
."

Lake Harney is 80 Miles North of C-54.

SJRWMD: "The role we play... as the District"
"Floodplain restoration — The District is restoring
floodplain and wetland systems throughout the
18 counties within its service area in north and
east-central Florida. The projects focus on restoringand enhancing wetlands for flood protection and wildlife habitat, emphasizing the natural function of the environment with limited reliance on structures such as dams and weirs
."

Read: Flood us out & let the river have its own way.
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Quoting stillwaiting:
ossg:ready for some of nature's rock'n'roll tonight????,maybe it'll cut the heat index down below 90*F,its been there for about a week strait now.....maybe a isolated severe storm in swfl over the next 8-12hrs,IMO...the stage is set for a few


It seems to be moving our way. I am still 3' down on my lake. I welcome it with open arms.

Single for 2 weeks with summer vaca for kids and mom. This does not seem fair with the work thing.

Note to self, no more fuzzy english muffin /Slim Jim sandwiches with cheese !


Member Since: June 12, 2005 Posts: 6 Comments: 8185
nice Pat...I never got the golf thing...but she loves it...
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Aussie, post 353.
OOoops, sorry, I did not see them then.
ossg:ready for some of nature's rock'n'roll tonight????,maybe it'll cut the heat index down below 90*F,its been there for about a week strait now.....maybe a isolated severe storm in swfl over the next 8-12hrs,IMO...the stage is set for a few
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Quoting Ossqss:



Right on target! You can get an inspection around $100, depending on where you are in FL, and get a discount. Most folks don't realize that their insurer is going with the worst case senario for coverage. Meaning you have te worst possible construction on your house. You must prove, via inspection, what you have and they have to give you a discount, per Law in FL.

PS, it is more than just screws, it is the frequency per the NOA. How many per so much distance and any helpers required, washers etc.


Yes they are going worst case scenario unless... You buy a new home in Miami-Dade county which has the toughest building codes in the U.S.
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Oh man...you bloggers are great! What if I had said Laverne and Shirley?
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About

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