MAR 2017
CTP Webinar: Vertical Datums - How they Impact Modeling & Mapping
Locations: CTP Information Exchange Webinar
Time: Wednesday, Mar 29, 2017, 2:00 PM - Wednesday, Mar 29, 2017, 3:00 PM

A vertical datum provides a base value from which elevations or heights are determined. There are two types of vertical datums: tidal and geodetic. This webinar is designed to provide an understanding of the relationship between tidal datums, North American Vertical Datum of 1988 (NAVD88), National Geodetic Vertical Datum of 1929 (NGVD29) and International Great Lakes Datum of 1985 (IGLD85). In addition, the webinar will discuss how to deal with mixed datums with flood hazard modeling.


  • Alan Lulloff, ASFPM Science Services
  • Doug Marcy, NOAA
  • Brandon Krumwiede, NOAA


  • Introduction - Alan Lulloff
  • Definition and overview of vertical datums - Doug Marcy
  • History of previous datums - Doug Marcy
  • International Great Lakes Datum 1985 (IGLD85) - Brandon Krumwiede
  • Transformations - Doug Marcy
  • NOAA VDATUM - Doug Marcy
  • Upcoming GRAV-D - Doug Marcy
  • Questions/Discussion

Vertical Datums CTP Webinar Slides

Vertical Datums CTP Webinar Recording


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