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Maps of Lands Vulnerable to Sea Level Rise

By James G. Titus and Charlie Richman

Maps of Lands Vulnerable to Sea Level Rise: Modeled Elevations along the U.S. Atlantic and Gulf Coasts (PDF) (34 pp., 714 KB,) was originally published in Climate Research (2001).

The report's Abstract is available below, along with a State by State Table showing the area of land on the Atlantic and Gulf Coasts that is close to sea level (i.e., elevation less than 1.5 meters and elevation between 1.5 and 3.5 meters) and a Regional Table presenting similar information relative to EPA's 1989 Report to Congress.

You may also go directly to the Sea Level Rise Maps that were produced in conjunction with this report; the report contains only four of these maps, however, all of the maps went through the same review process and together constitute an "unpublished appendix" to the article. The individual maps in this section are available in several formats, including high-quality, full page slides (in pdf format) suitable for printing. Finally, you can download the underlying geographical information system (GIS) data for an example quadrangle and learn how to obtain the entire dataset underlying this study.

This site also has better elevation maps and sea level rise planning maps for most of the Atlantic Coast south of New England. For additional reports focused on the implications of rising sea level, please go up one level to More Sea Level Rise Reports section.


Understanding the broad-scale ramifications of accelerated sea level rise requires maps of the land that could be inundated or eroded. Producing such maps requires a combination of elevation information and models of shoreline erosion, wetland accretion, and other coastal processes. Assessments of coastal areas in the United States that combine all of these factors have focused on relatively small areas, usually 25 to 30 kilometers wide. In many cases, the results are as sensitive to uncertainty regarding geological processes as to the rate of sea level rise.

This paper presents maps illustrating the elevations of lands close to sea level. Although elevation contours do not necessarily coincide with future shorelines, the former is more transparent and less dependent on subjective modeling. Several methods are available for inferring elevations given limited data. This paper uses the USGS 1-degree digital elevation series and NOAA shoreline data to illustrate the land below the 1.5- and 3.5-meter contours for areas the size of entire U.S. states or larger.

Because sea level is expected to rise about 60 cm (2 feet) along most of the U.S. Gulf and Atlantic Coast in the next century (EPA 1995), it would be preferable to illustrate the land that would be inundated with a 30 or 60 cm (1 or 2 foot) rise in sea level. Unfortunately, the 1.5-meter (5-foot) contour is the lowest elevation that can be consistently illustrated over large regions with the available digital data.

This does not mean, however, that these maps show the land that would be flooded with a 1.5-meter (5 foot) rise in sea level. For a variety of reasons, the 1.5-meter contour is only about 1.3 meters above mean sea level along most of the Atlantic and Gulf Coasts. Although tide ranges vary, mean spring high water (i.e. the typical high tide during new moon and full moon) is typically 60 cm above mean sea level. Therefore, the 1.5 meter contour roughly represents the area that would be inundated during spring high water with a 70 cm rise in sea level. Such a rise appears to be most likely to occur in the next 120 years, but has a 1% chance of occuring in the next 60 years. (See EPA 1995.)

The maps imply that approximately 58,000 square kilometers of land along the Atlantic and Gulf coasts lie below the 1.5-meter contour. Louisiana, Florida, Texas, and North Carolina account for more than 80 percent of the low land. Outside of those four states, the largest vulnerable populated region is the land along the Eastern Shore of Chesapeake Bay stretching from Dorchester County, Maryland to Accomac County, Virginia.

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Table 1
Amounts of Low Land Implied by Various Map Data Sets 1
(square kilometers)

State Elevation between 0 and 1.5 meters Elevation between 1.5 and 3.5 meters
Alabama 194.7 354.6
Connecticut 63.0 48.6
Delaware 387.8 172.0
District of Columbia 1.5 4.0
Florida 12,250.8 12,742.9
Georgia 1,742.6 1,078.3
Louisiana 24,724.7 4,345.2
Maine 382.9 176.1
Maryland 1,547.1 806.1
Massachusetts 364.7 375.0
Mississippi 173.2 824.1
New Hampshire 42.4 20.0
New Jersey 1,083.0 637.8
New York 239.9 265.8
North Carolina 5,835.9 3,864.6
Pennsylvania 2.5 2.5
Rhode Island 121.9 61.7
South Carolina 2,333.7 2,401.7
Texas 5,177.7 4,213.2
Virginia 968.5 1,041.4
Total 57,638.6 33,435.7
1. This version of Table 1 is edited from the original to facilitate presentation - see the Maps Report (PDF) (34 pp., 714 KB,) for additional detail.

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Table 2
Area of Land Close to Sea Level
Estimated by this Study and EPA Report to Congress 6
Land With Elevation Less than 1.5 Meters (square kilometers)

Region Maps in This Study Report to Congress:
Report to Congress:
Standard Deviation
Northeast 1 974 839 490
Mid-Atlantic 2 4227 4685 1274
South Atlantic 3 12339 9433 3313
S & SW Florida 4 8744 4605 2168
Louisiana 24724 14856 4416
Other Gulf 5 6625 5879 4312
1. Maine, New Hampshire, Massachusetts, Rhode Island, and Connecticut.
2. New York, New Jersey, Delaware, Pennsylvania, Maryland, Virginia, and District of Columbia.
3. North and South Carolina, Georgia, and the portion of Florida's Atlantic Coast above 26°N latitude.
4. The portion of South Florida below 26° latitude, and the portion of the Gulf of Mexico coast of Florida east of 84°W longitude.
5. Texas, Mississippi, Alabama, and the Florida panhandle west of 84°W longitude.
6. These results are arithmetic averages of the estimates for the loss of land from a 1-meter and a 2-meter rise in sea level, as reported by Titus and Greene (1989), Tables 4 and 5. The underlying data for those tables was the Park et al. 1989 study. For the nongovernmental summary of this study, see Titus, Park, et al. (1991).

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