These data were created as part of the National Oceanic and Atmospheric Administration Office for Coastal Management's efforts to create an onlinemapping viewer depicting potential sea level rise and its associated impacts on the nation's coastal areas. The purpose of the mapping vieweris to provide coastal managers and scientists with a preliminary look at sea level rise (slr) and coastal flooding impacts. The viewer is ascreening-level tool that uses nationally consistent data sets and analyses.Data and maps provided can be used at several scales to helpgauge trends and prioritize actions for different scenarios. The Sea Level Rise and Coastal Flooding Impacts Viewer may be accessed at:https://www.coast.noaa.gov/slr. These data depict the potential inundation of coastal areas resulting from a projected 1 to 10 feet rise in sea level above currentMean Higher High Water (MHHW) conditions. The process used to produce the data can be described as a modified bathtub approach that attemptsto account for both local/regional tidal variability as well as hydrological connectivity. The process uses two source datasets to derive thefinal inundation rasters and polygons and accompanying low-lying polygons for each iteration of sea level rise: the Digital Elevation Model (DEM)of the area and a tidal surface model that represents spatial tidal variability. The tidal model is created using the NOAA National GeodeticSurvey's VDATUM datum transformation software (http://vdatum.noaa.gov) in conjunction with spatial interpolation/extrapolation methods andrepresents the MHHW tidal datum in orthometric values (North American Vertical Datum of 1988).The model used to produce these data does not account for erosion, subsidence, or any future changes in an area's hydrodynamics. It is simplya method to derive data in order to visualize the potential scale, not exact location, of inundation from sea level rise.

The process to derive the inundation rasters and polygons and low-lying area polygons is as follows:

1. A tidal surface is generated using NOAA VDATUM tool and various spatial interpolation/extrapolation routines, dependent upon the areabeing mapped. The surface generated represents the spatial variability of offsets between MHHW, a tidal datum and NAVD88, an orthometricdatum.

2. Using the DEM and the tidal surface, raster calculations are made using ArcGIS Spatial Analyst Raster Calculationtool to generate multiple rasters, one 32-bit floating point raster representing depth of inundation and one 8-bit single value rasterrepresenting the extent of inundation.

3. The hydrologic connectivity of the single value raster is evaluated using an 8-sided neighborhood rule in ArcGIS using the RegionGroup tool.The output raster from this process is then converted to a vector polygon feature class for further analysis. Using this 'base' feature class,a new feature class is created representing hydrologically connected areas. The 'base' feature class is also used to create a feature classrepresenting unconnected 'low-lying' areas.

Disclaimer: This product is for informational purposes only and may not be suitable for legal, engineering, or surveying purposes. It does not represent an official survey and represents only the approximate relative location of features and boundaries. Mapping may not necessarily reflect on-the-ground conditions. This product and those involved in its production make no claims as to the accuracy or reliability of the data, and neither assumes, nor will accept liability for their use.

These data were created as part of the National Oceanic and Atmospheric Administration Office for Coastal Management's efforts to create an onlinemapping viewer depicting potential sea level rise and its associated impacts on the nation's coastal areas. The purpose of the mapping vieweris to provide coastal managers and scientists with a preliminary look at sea level rise (slr) and coastal flooding impacts. The viewer is ascreening-level tool that uses nationally consistent data sets and analyses.Data and maps provided can be used at several scales to helpgauge trends and prioritize actions for different scenarios. The Sea Level Rise and Coastal Flooding Impacts Viewer may be accessed at:https://www.coast.noaa.gov/slr. These data depict the potential inundation of coastal areas resulting from a projected 1 to 10 feet rise in sea level above currentMean Higher High Water (MHHW) conditions. The process used to produce the data can be described as a modified bathtub approach that attemptsto account for both local/regional tidal variability as well as hydrological connectivity. The process uses two source datasets to derive thefinal inundation rasters and polygons and accompanying low-lying polygons for each iteration of sea level rise: the Digital Elevation Model (DEM)of the area and a tidal surface model that represents spatial tidal variability. The tidal model is created using the NOAA National GeodeticSurvey's VDATUM datum transformation software (http://vdatum.noaa.gov) in conjunction with spatial interpolation/extrapolation methods andrepresents the MHHW tidal datum in orthometric values (North American Vertical Datum of 1988).The model used to produce these data does not account for erosion, subsidence, or any future changes in an area's hydrodynamics. It is simplya method to derive data in order to visualize the potential scale, not exact location, of inundation from sea level rise.

The process to derive the inundation rasters and polygons and low-lying area polygons is as follows:

1. A tidal surface is generated using NOAA VDATUM tool and various spatial interpolation/extrapolation routines, dependent upon the areabeing mapped. The surface generated represents the spatial variability of offsets between MHHW, a tidal datum and NAVD88, an orthometricdatum.

2. Using the DEM and the tidal surface, raster calculations are made using ArcGIS Spatial Analyst Raster Calculationtool to generate multiple rasters, one 32-bit floating point raster representing depth of inundation and one 8-bit single value rasterrepresenting the extent of inundation.

3. The hydrologic connectivity of the single value raster is evaluated using an 8-sided neighborhood rule in ArcGIS using the RegionGroup tool.The output raster from this process is then converted to a vector polygon feature class for further analysis. Using this 'base' feature class,a new feature class is created representing hydrologically connected areas. The 'base' feature class is also used to create a feature classrepresenting unconnected 'low-lying' areas.

Disclaimer: This product is for informational purposes only and may not be suitable for legal, engineering, or surveying purposes. It does not represent an official survey and represents only the approximate relative location of features and boundaries. Mapping may not necessarily reflect on-the-ground conditions. This product and those involved in its production make no claims as to the accuracy or reliability of the data, and neither assumes, nor will accept liability for their use.