Amsterdam Ordnance Datum
Amsterdam Ordnance Datum or Normaal Amsterdams Peil (NAP) is a vertical datum in use in large parts of Western Europe. Originally created for use in the Netherlands, its height was used by Prussia in 1879 for defining Normalnull, and in 1955 by other European countries. In the 1990s, it was used as the reference level for the United European leveling Network (UELN) which in turn led to the European Vertical Reference System (EVRS).[1]
Mayor
The relatively constant water level in the canals of Amsterdam, called Amsterdams Peil ("Amsterdam level", AP), was equal to the level at summer flood at sea in the sea-inlet, which changes throughout the year. AP was carried over to other areas in the Netherlands in 1860, to replace locally used levels. In this operation, an error was introduced which was corrected (normalised) between 1885 and 1894, resulting in the Normaal Amsterdams Peil.
Originally the zero level of NAP was the average summer flood water level in the IJ just north of the centre of Amsterdam (which was at the time, in 1684, the main shipping area, then still connected with the open sea). Currently it is physically realised by a brass benchmark on a 22-metre (72 ft) pile below the
(combined city hall and opera house), which is a tourist attraction, is no longer used as a reference point.See also
- Above mean sea level
- Normalnull – German height reference system derived from Amsterdam Ordnance Datum
- Normalhöhennull – Current German height reference system linked to NAP
References
- ^ "European Vertical Reference System". bund.de. Retrieved 9 July 2015.
- ISBN 9061320224.
- ^ Herberekening van het primaire net van het NAP (Dutch only)
External links
- P.I. van der Weele: De geschiedenis van het N.A.P. 1971, Dutch Royal Society for Sciences, Governmental Commission for Geodesy (in Dutch and English)
- Frans J.P.M. Kwaad: Het Normaal Amsterdams Peil (NAP) - Achtergronden en geschiedenis (in Dutch)