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What does NAVD 88 stand for?
Is NGVD 29 the same as NAVD 88?
What is the average conversion to NAVD 88?
When did NGVD 88 come out?
Jul 12, 2018 · The North American Vertical Datum of 1988 (NAVD 88) is the vertical control datum established in 1991 by the minimum-constraint adjustment of the Canadian-Mexican-United States leveling observations.
Conversion between NAVD 88 and the commonly used NGVD 29 varies spatially; however, over most of the study area the following conversion can be used: NGVD 29 = NAVD 88 –3.6 feet. This conversion generally is accurate within about ± 0.5 feet for 95 percent of the study area.
document contains the following information about conversion from NGVD 29 to NAVD 88: General information about the two vertical datums most commonly used by FEMA for referencing 1-percent-annual-chance flood elevation information in Flood Insurance Rate Map (FIRM)
Nov 4, 2020 · Despite the huge leap in accuracy from NGVD 29 to NAVD 88, the latter datum, like its predecessors, was still based on terrestrial survey marks that could be damaged or knocked out of position. According to the NGS, the 1988 datum was off by about 1 m coast to coast.
What is the North American Vertical Datum of 1988 (NAVD 88)? NAVD 88 was established in 1991. In 1993, Congress adopted NAVD 88 as the official civilian vertical datum for the United States and instructed all federal agencies to upgrade to the new datum.
To convert to NGVD 29 to NAVD 88 you simply add 3.6 feet. So the 29 ft lake elevation (MSL or NGVD 29) is 32.6 ft NAVD 88. For a good writeup on this, see: https://c4g.lsu.edu/index.php/ticket-system/faq/IS- NGVD29-THE-SAME-AS-MEAN-SEA-LEVEL-10.
NAVD 1988 is the newer elevation datum. An easy way to convert BFE data is through the National Geodetic Survey (NGS) online tool known as VERTCON. Select this link to view and use the VERTCON site. You can also contact the appropriate floodplain administrator for guidance.
