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Sea Level Datum of 1929

 

 
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Sea Level Datum of 1929
 
 
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The Sea Level Datum of 1929 was the vertical control datum established for vertical control surveying
Surveying

Surveying or land surveying is the technique and science of accurately determining the terrestrial or three-dimensional space position of points and the distances and angles between them....
 in the United States of America
United States

The United States of America is a Federal government constitutional republic comprising U.S. state and a federal district. The country is situated mostly in central North America, where its Contiguous United States and Washington, D.C., the Capital districts and territories, lie between the Pacific Ocean and Atlantic Oceans, Borders of the U...
 by the General Adjustment of 1929. The datum was used to measure elevation
Elevation

The elevation of a geographic location is its height above a fixed reference point, often the above mean sea level. Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a s...
 or altitude
Altitude

Altitude has multiple uses depending on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object....
 above, and depression
Depression (geology)

Depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms, and may be referred to by a variety of technical terms....
 or depth
Depth

The term Depth may refer to: How deep something is. How far down.* Depth perception, 3d shapes* Depth of moral character* Depth in a well* Depth of a river...
 below, mean sea level (MSL).

Mean sea level was measured at 26 tide gauges: 21 in the United States and 5 in Canada
Canada

Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean....
. The datum was defined by the observed heights of mean sea level at the 26 tide gauges and by the set of elevations of all bench marks resulting from the adjustment.






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The Sea Level Datum of 1929 was the vertical control datum established for vertical control surveying
Surveying

Surveying or land surveying is the technique and science of accurately determining the terrestrial or three-dimensional space position of points and the distances and angles between them....
 in the United States of America
United States

The United States of America is a Federal government constitutional republic comprising U.S. state and a federal district. The country is situated mostly in central North America, where its Contiguous United States and Washington, D.C., the Capital districts and territories, lie between the Pacific Ocean and Atlantic Oceans, Borders of the U...
 by the General Adjustment of 1929. The datum was used to measure elevation
Elevation

The elevation of a geographic location is its height above a fixed reference point, often the above mean sea level. Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a s...
 or altitude
Altitude

Altitude has multiple uses depending on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object....
 above, and depression
Depression (geology)

Depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms, and may be referred to by a variety of technical terms....
 or depth
Depth

The term Depth may refer to: How deep something is. How far down.* Depth perception, 3d shapes* Depth of moral character* Depth in a well* Depth of a river...
 below, mean sea level (MSL).

Mean sea level was measured at 26 tide gauges: 21 in the United States and 5 in Canada
Canada

Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean....
. The datum was defined by the observed heights of mean sea level at the 26 tide gauges and by the set of elevations of all bench marks resulting from the adjustment. The adjustment required a total of 66,315 miles (106,724 km) of leveling with 246 closed circuits and 25 circuits at sea level.

Since the Sea Level Datum of 1929 was a hybrid model, it was not a pure model of mean sea level, the geoid
Geoid

The geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth, if the oceans were in equilibrium, at rest, and extended through the continents ....
, or any other equipotential
Equipotential

Equipotential or isopotential in mathematics and physics refers to a region in space where every point in it is at the same potential. This usually refers to a scalar potential, although it can also be applied to vector potentials....
 surface. Therefore, it was renamed the National Geodetic Vertical Datum of 1929 (NGVD 29) in 1973. The NGVD 29 was subsequently replaced by the North American Vertical Datum of 1988
North American Vertical Datum of 1988

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

See also

  • Altitude
    Altitude

    Altitude has multiple uses depending on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object....
  • Datum (geodesy)
  • Geodesy
    Geodesy

    Geodesy , also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space....
  • Mean sea level
  • North American Vertical Datum of 1988
    North American Vertical Datum of 1988

    The North American Vertical Datum of 1988 is the vertical control Datum established for vertical control surveying in the United States based upon the General Adjustment of the North American Datum of 1988....
  • Storm Surge
    Storm surge

    Storm surge is an offshore rise of water associated with a low pressure area weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface....
  • Topographic elevation
  • Topography
    Topography

    Topography is the study of Earth's surface shape and features or those ofplanets, Natural satellite, and asteroids. It is also the description of such surface shapes and features ....


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