Data Management Plan

These data were created as part of the National Oceanic and Atmospheric Administration Office for Coastal Management's efforts to create an online

mapping viewer depicting potential sea level rise and its associated impacts on the nation's coastal areas. The purpose of the mapping viewer

is to provide coastal managers and scientists with a preliminary look at sea level rise (slr) and coastal flooding impacts. The viewer is a

screening-level tool that uses nationally consistent data sets and analyses. Data and maps provided can be used at several scales to help gauge

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 current Mean Higher High Water (MHHW) conditions. The process used

to produce the data can be described as a modified bathtub approach that attempts to account for both local/regional tidal variability as

well as hydrological connectivity. The process uses two source datasets to derive the final inundation rasters and polygons and accompanying

low-lying polygons: 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 Geodetic Survey's VDATUM datum transformation software (http://vdatum.noaa.gov) in conjunction

with spatial interpolation/extrapolation methods and represents 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 simply

a method to derive data in order to visualize the potential scale, not exact location, of inundation from sea level rise.

Process Steps:

• 2016-01-01 00:00:00 - 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 area being mapped. The surface generated represents the spatial variability of offsets between MHHW, a tidal datum and NAVD88, an orthometric datum. 2. Using the DEM and the tidal surface, raster calculations are made using ArcGIS Spatial Analyst Raster Calculation tool to generate multiple rasters, one 32-bit floating point raster representing depth of inundation and one 8-bit single value raster representing 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 class representing unconnected 'low-lying' areas. (Citation: NOAA OCM Digital Elevation Models)

This data may be downloaded at: https://www.coast.noaa.gov/slrdata;