Geodesy
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Fundamentals
Geodesy · Geodynamics
Geomatics · Cartography
Concepts
Datum · Distance · Geoid
Figure of the Earth
Geodetic system
Geog. coord. system
Hor. pos. representation
Map projection
Reference ellipsoid
Satellite geodesy
Spatial reference system
Technologies
GNSS · GPS · GLONASS
Standards
ED50 · ETRS89 · GRS 80
NAD83 · NAVD88 · SAD69
SRID · UTM · WGS84
History
History of geodesy
NAVD29

The North American Vertical Datum of 1988 (NAVD 88) is the vertical control datum of orthometric height established for vertical control surveying in the United States of America based upon the General Adjustment of the North American Datum of 1988.

The NAVD 88 was established in 1991 by the minimum-constraint adjustment of geodetic leveling observations in Canada, the United States, and Mexico. It held fixed the height of the primary tidal bench mark, referenced to the International Great Lakes Datum of 1985 local mean sea level height value, at Rimouski, Quebec, Canada. Additional tidal bench mark elevations were not used due to the demonstrated variations in sea surface topography, i.e., the fact that mean sea level is not the same equipotential surface at all tidal bench marks.

The NAVD 88 replaced the National Geodetic Vertical Datum of 1929 (NGVD 29), previously known as the Sea Level Datum of 1929. It is important to note that, while the computed elevation of some fixed point might differ depending on which datum is used, the elevation of that point relative to some other nearby point did not change with that datum change.

See also

External links