|NTHMP DEM Project
|NOAA’s National Geophysical Data Center (NGDC) is building high-resolution digital
elevation models (DEMs) to support individual coastal States as part of the National
Tsunami Hazard Mitigation Program’s (NTHMP) efforts to improve community preparedness
and hazard mitigation. These integrated bathymetric-topographic DEMs are used to support
tsunami and coastal inundation mapping. Bathymetric, topographic, and shoreline data
used in DEM compilation are obtained from various sources, including NGDC, the U.S.
National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps
of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal,
state, and local government agencies, academic institutions, and private companies.
DEMs are referenced to various vertical and horizontal datums depending on the specific
modeling requirements of each State. For specific datum information on each DEM, refer
to the appropriate DEM documentation. Cell sizes also vary depending on the specification
required by modelers in each State, but typically range from 8/15 arc-second (~16
meters) to 8 arc-seconds (~240 meters).