This page contains Mean Higher High Water (MHHW) tidal surfaces used in NOAA OCM’s sea level rise mapping. These data are a derived product of the NOAA VDatum tool and they extend the tool's MHHW tidal datum conversion inland beyond its original extent. VDatum was designed to vertically transform geospatial data among a variety of tidal, orthometric and ellipsoidal datums - allowing users to convert their data from different horizontal/vertical references into a common system and enabling the fusion of diverse geospatial data in desired reference levels. However, VDatum's conversion extent does not completely cover tidally-influenced areas along the coast. For more information on why VDatum does not provide tidal datums inland, see http://vdatum.noaa.gov/docs/faqs.html. Because of the extent limitation and since most inundation mapping activities use a tidal datum as the reference zero (e.g., 1 meter of sea level rise on top of MHHW), NOAA OCM created these data for the purpose of extending the MHHW tidal datum beyond the areas covered by VDatum. The data do not replace VDatum, nor do they supersede the valid datum transformations VDatum provides. However, the data are based on VDatum's underlying transformation data and do provide an approximation of MHHW where VDatum does not provide one. In addition, the data are in a GIS-friendly format and represent MHHW in NAVD88, which is the vertical datum by which most topographic data are referenced. Data are in the UTM NAD83 projection. Horizontal resolution varies by VDatum region, but is either 50m or 100m. Data are vertically referenced to NAVD88 (Geoid12b) meters.
Files:
A text file list of URLs is avaliable to facilitate downloading these files (URLlist_Tidal_Surfaces.txt).
Website Owner: NOAA Office for Coastal Management | Last Modified: Thu Feb 27 11:15:07 2025