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Sea Level Rise Viewer

Sea Level Rise

View sea level rise and potential coastal flooding impact areas and relative depth.

Local Scenarios

Compare inundation levels to local relative sea level rise scenarios.

Mapping Confidence

View the level of confidence in the base data used for mapping inundation levels.

Marsh Migration

View potential changes in marsh and other land cover types based on inundation levels.

Vulnerability

View the potential impact of sea level rise and coastal flooding on a vulnerable population.

Flood Frequency

View areas susceptible to shallow coastal flooding, or “nuisance flooding,” and the frequency and duration of these events.

Disclaimer

The data and maps in this tool illustrate the scale of potential flooding, not the exact location, and do not account for erosion, subsidence, or future construction. Water levels are relative to Mean Higher High Water (MHHW) (excludes wind driven tides). The data, maps, and information provided should be used only as a screening-level tool for management decisions. As with all remotely sensed data, all features should be verified with a site visit. The data and maps in this tool are provided “as is,” without warranty to their performance, merchantable state, or fitness for any particular purpose. The entire risk associated with the results and performance of these data is assumed by the user. This tool should be used strictly as a planning reference tool and not for navigation, permitting, or other legal purposes.

April 2017

Mississippi - Remapped with new elevation data. New DEM available.

San Francisco Bay - Remapped with updated VDatum tidal surface.

Important – Transformation uncertainties in the "Louisiana/Mississippi–Eastern Louisiana to Mississippi Sound" regional model have been found to range from 20 to 50 centimeters in particular locations from the Mississippi River Delta north to Lake Pontchartrain. These issues most likely can be attributed to subsidence, newly established datums, and changes to the understanding of NAVD88 based on new versions of the GEOID. The VDatum team is currently looking at resolving these uncertainties.

August 2016

Northern South Carolina, North Carolina, Virginia, Maryland, Delaware, New Jersey, and New York – Remapped with new elevation data based on Post-Sandy lidar from USGS and NOAA National Geodetic Survey. New DEMs available.

2015

San Francisco Bay, CA – Remapped to fix leveed areas. Levees and leveed areas displayed.

Louisiana – Mapped and added to viewer. Levees and leveed areas displayed.

U.S. Virgin Islands – Remapped with new elevation data based on 2013 lidar from NOAA

Port Arthur, TX – Remapped to fix leveed area

Freeport, TX – Remapped to fix leveed area

Texas City, TX – Remapped to fix leveed area

Maryland/Delaware border – Remapped to fix edge matching issue.

North Carolina/South Carolina border – Remapped to fix edge matching issue

Palm City, FL – Fixed elevation model and remapped

Charles and Mystic Rivers near Boston, MA – Fixed elevation model and remapped to fix dam protected area

Tillamook Bay, OR – Added elevation data and remapped to fill data gap

Oregon and Texas – Marsh tab updated with 2010 Coastal Change Analysis Program (C-CAP) land cover data

Sea Level Rise

Use the vertical slider to simulate water level rise, the resulting inundation footprint, and relative depth. Click on icons in the map to view sea level rise simulations at specific locations.

Water levels are relative to local Mean Higher High Water Datum. Areas that are hydrologically connected to the ocean are shown in shades of blue (darker blue = greater depth).

Low-lying areas, displayed in green, are hydrologically "unconnected" areas that may also flood. They are determined solely by how well the elevation data captures the area’s drainage characteristics. The mapping may not accurately capture detailed hydrologic/hydraulic features such as canals, ditches, and stormwater infrastructure. A more detailed analysis, may be required to determine the area’s actual susceptibility to flooding.

There is not 100% confidence in the elevation data and/or mapping process. It is important not to focus on the exact extent of inundation, but rather to examine the level of confidence that the extent of inundation is accurate (see mapping confidence tab).

Scenarios

Zoom to your area of interest and click on the closest Scenario Location icon in the map. The selected gauge will be displayed on the bottom of the slider panel.

“View by Year” (default): Select a year by sliding the year marker on the right to view the amount of relative sea level rise associated with that year for each of the five local sea level rise scenarios on the left (intermediate Low, intermediate, intermediate high, high, extreme). Adjust the one foot increment map layers (circle) to view the potential inundation impacts for each scenario.

“View by Scenario”: Select a local scenario by sliding the scenario marker on the right to view the amount of relative sea level rise associated with that scenario in 20-year increments displayed on the left. Adjust the one foot increment map layers (circle) to view the potential inundation impacts for each year increment.

Understanding the Scenarios

The five relative sea level rise (RSL) scenarios shown in this tab are derived from NOAA Technical Report NOS CO-OPS 083 “Global and regional sea level rise scenarios for the United States” using the same methods as the USACE Sea Level Rise Calculator. These new scenarios were developed by the Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council as input to the USGCRP Sustained Assessment process and 4th National Climate Assessment. These RSL scenarios provide a revision to the (Parris et. al, 2012) global scenarios which were developed as input to the 3rd National Climate Assessment.

These RSL scenarios begin in year 2000 and take into account global mean sea level rise (GMSL), regional changes in ocean circulation, changes in Earth’s gravity field due to ice melt redistribution, and local vertical land motion.

A RSL-change adjustment to the current National Tidal Datum Epoch (1983-2001) will cause a minimal offset that may be needed for some applications. The USACE sea level rise calculator can correct for this offset.

For almost all the scenarios, RSL rise is likely to be greater than the global average in the U.S. Northeast and the western Gulf of Mexico. In intermediate and low scenarios, RSL rise is likely to be less than the global average in much of the Pacific Northwest and Alaska. For high scenarios, RSL rise is likely to be higher than the global average along all U.S. coastlines outside Alaska.

Rounding to the nearest one foot mapping increment to view potential impacts is appropriate based on the accuracy of the elevation and tidal surface data used as mapping inputs.

Note: We do not show the low scenario as it is a simple extrapolation of the current sea level trend into the future and has been determined to have a low probability of occurring by 2100. Furthermore, this scenario would be associated with low levels of risk even if it did occur.

Mapping Confidence

The inundation areas depicted in the Sea Level Rise tab are not as precise as they may appear. There are many unknowns when mapping future conditions, including natural evolution of the coastal landforms (e.g., barrier island overwash and migration), as well as the data used to predict the changes. The presentation of confidence in these maps only represents the known error in the elevation data and tidal corrections.

Blue areas denote a high confidence of inundation, orange areas denote a high degree of uncertainty, and unshaded areas denote a high confidence that these areas will be dry given the chosen water level.

In this application 80% is considered a high degree of confidence such that, for example, the blue areas denote locations that may be correctly mapped as 'inundated' more than 8 out of 10 times. Areas with a high degree of uncertainty represent locations that may be mapped correctly (either as inundated or dry) less than 8 out of 10 times. For a detailed description of the confidence levels and their computation, see the methods document.

Marsh

Zoom to your area of interest and click on the closest Scenario Location icon in the map. The selected gauge will be displayed on the bottom of the slider panel.

“View by Year” (default): Select a year by sliding the year marker on the right to view the amount of relative sea level rise associated with that year for each of the five local sea level rise scenarios on the left (intermediate Low, intermediate, intermediate high, high, extreme). Adjust the half foot increment map layers (circle) to view the potential inundation impacts for each scenario.

“View by Scenario”: Select a local scenario by sliding the scenario marker on the right to view the amount of relative sea level rise associated with that scenario in 20-year increments displayed on the left. Adjust the half foot increment map layers (circle) to view the potential inundation impacts for each year increment.

“Accretion Rate”: Customize the selected accretion rate to reflect sediment accumulation conditions that best reflect your area. These rates are flat values applied across the landscape and can be used to highlight how accretion can offset sea level rise.

Predictions represent the potential distribution of each wetland type (see legend) based on their elevation and how frequently they may be inundated under each scenario. As sea levels increase, some marshes may migrate into neighboring low-lying areas, while other sections of marsh will change type or be lost to open water.

Understanding the Scenarios

There are five scenarios of relative sea level rise (RSL) shown in this tab (intermediate Low, intermediate, intermediate high, high, extreme). All begin in year 2000 and take into account global mean sea level rise (GMSL), regional changes in ocean circulation, changes in Earth’s gravity field due to ice melt redistribution, and local vertical land motion.

The scenarios are derived from NOAA Technical Report NOS CO-OPS 083 “Global and regional sea level rise scenarios for the United States”. You can learn more about them by reading this report, exploring the USACE Sea Level Rise Calculator, and within the Local Scenarios Tab of this viewer.

Note: We do not show the low scenario as it is a simple extrapolation of the current sea level trend into the future and has been determined to have a low probability of occurring by 2100. Furthermore, this scenario would be associated with low levels of risk even if it did occur.

Social Vulnerability

By overlaying social and economic data on a map that depicts sea level rise, a community can see the potential impact that sea level rise can have on vulnerable people and businesses.

The Social Vulnerability Index, which shows areas of high human vulnerability to hazards, is based on population attributes from Census 2010 (e.g., age and poverty) and the built environment. By looking at the intersection of potential sea level rise and vulnerable Census tracts, one can get an idea of how vulnerable populations might be affected by sea level rise. Dark red indicates tracts having a high vulnerability, and the lighter reds indicate decreasing vulnerability.

Flood Frequency

Annual occurrences of tidal flooding—exceeding local thresholds for minor impacts to infrastructure—have increased 5- to 10-fold since the 1960s in several U.S. coastal cities. The changes in flood frequency over time are greatest where elevation is lower, local RSL rise is higher, or extreme variability is less.

In a sense, today’s flood will become tomorrow’s high tide, as sea level rise will cause flooding to occur more frequently and last for longer durations of time.

The red layer in the map represents areas currently subject to tidal flooding, often called “recurrent or nuisance flooding”.

Click on a NOAA tide station icon in the map to see information on the current frequency of coastal flood events and durations as compared to hypothetical half-meter and one-meter sea level rise scenarios.

Understanding The Map

Tidal (Recurrent or Nuisance Flooding): Many coastal areas experience periodic minor-to-moderate shallow coastal flooding events―typically as a result of meteorological factors that include high tides, winds, and rain. These events often affect roadways, buildings, and other infrastructure.

Local Thresholds: This map illustrates the extent of flood-prone coastal areas based on predicted water levels at local tide gauges that may exceed defined minor flooding thresholds. Local National Weather Service Weather Forecast Offices define the flooding thresholds and issue coastal flood advisories.

Frequency and Duration: The coastal flood event frequencies and durations for tide gauges were calculated using observed tidal data over a five year period (2010-2015). The future frequency and duration predictions are based on the addition of half-meter (1.64 ft) and one-meter (3.28 ft) sea level rise scenarios to the observed water levels over the three-year period.

About Sea Level Rise Viewer v 3.0.0

The purpose of this map viewer is to provide federal, state, and local coastal resource managers and planners with a preliminary look at sea level rise and coastal flooding impacts. The viewer is a screening-level tool that uses best-available, nationally consistent data sets and analyses. Data and maps provided can be used at several scales to help estimate impacts and prioritize actions for different scenarios.

The data and maps in this tool illustrate the scale of potential flooding, not the exact location, and do not account for erosion, subsidence, or future construction. Water levels are shown as they would appear during the highest high tides (excludes wind-driven tides). The data, maps, and information provided should be used only as a screening-level tool for management decisions. As with all remotely sensed data, all features should be verified with a site visit. The data and maps in this tool are provided “as is” without warranty to their performance, merchantable state, or fitness for any particular purpose. The entire risk associated with the results and performance of these data is assumed by the user. This tool should be used strictly as a planning reference tool and not for navigation, permitting, or other legal purposes.

Links

United States Department of Commerce | National Oceanic and Atmospheric Administration | National Ocean Service | Website owner: Office for Coastal Management | Last Modified: 1/31/2017

Contact Us | Privacy Policy | Link Disclaimer | USA.gov

Mapping Methods

Additional Resources

Leveed Areas Disclaimer

Levees are displayed as yellow lines, and enclosed leveed areas are displayed as a white stippled pattern.

Major federal leveed areas were assumed high enough and strong enough to protect against inundation depicted in this viewer, and therefore no inundation was mapped in these regions.

Minor (nonfederal) leveed areas were mapped using the best available elevation data that capture leveed features. In some cases, however, breaks in elevation occur along leveed areas because of flood control features being removed from elevation data, limitations of the horizontal and vertical resolution of the elevation data, the occurrence of levee drainage features, and so forth. Flooding behind levees is only depicted if breaks in elevation data occur or if the levee elevations are overtopped by the water surface. At some flood levels, alternate pathways around—not through—levees, walls, dams, and flood gates may exist that allow water to flow into areas protected at lower levels. In general, imperfect levee and elevation data make assessing protection difficult, and small data errors can have large consequences.

As new elevation data become available, or as stakeholders provide additional levee information, the NOAA Office for Coastal Management will periodically update the inundation and levee data.