Amsterdam level

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Marking from 1684 on the Eenhoornsluis, 2.67 m above zero level
Zero level in Amsterdam

Amsterdam level (later also Normaal Amsterdams Peil , or NAP for short, as height reference point ) is a German name for the zero point of a height determination in Amsterdam , which was first mentioned in 1674.

history

The zero point was determined after measuring the water level ( level ) of the IJ , an inlet of the former North Sea bay Zuiderzee , at the Haarlemmer lock ( Haarlemmersluis ) in Amsterdam in the period between September 1, 1683 and September 1, 1684 The water level of the mean high water (MHW) of this period was chosen. This water level was approx. 17 cm above mean water (34 cm tidal range ). The height was recorded by eight marble tablets with notches on them marked a height of 2.67 m (9 feet and 5 thumbs) above zero. At least one plaque (called "Huddesteen" after Johan Hudde ), namely the one on the Eenhoornsluis, has been preserved to this day. By royal decree, this zero point was set by Wilhelm I on February 18, 1818 as the starting point for the height information ( reference height ) for the entire Netherlands . This altitude was later adopted as a reference in some neighboring countries, for example in 1878 by Prussia for the normal high point in 1879 , from which the reference level for the whole of Germany was then derived.

At the end of the 19th century, Amsterdams Peil (AP) was renamed Normaal Amsterdams Peil (NAP). The European Union is striving to introduce a uniform reference level for all of Europe. The height definition Normaal Amsterdams Peil (NAP) was adopted as the zero point.

The water level in Amsterdam has long since changed due to hydraulic engineering measures (e.g. the IJsselmeer ), which is why the term "former Amsterdam level" is sometimes used. For example, the water level of the Amsterdam canals is around 40 cm below the NAP zero point today. In the meantime, the original mean flood (MHW) is no longer at the zero point of the Amsterdam level, but rather the NAP zero point is currently roughly at the level of the mean water (MW) of the North Sea. The accuracy of the height definition is not affected. Since the establishment of the zero point, the altitude is in principle independent of fluctuations in the water level . Only the word level in the name reminds of the dependence on a water level .

An exhibition on the Amsterdam level is now in the City Hall ( Stadhuis ) of Amsterdam. Three columns show the water level in the North Sea near IJmuiden , the current water level in the Westerschelde near Vlissingen and a water level from the flood disaster of 1953 , which in Vlissingen was 4.55 meters above zero.

See also

Web links

Commons : Amsterdam level  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b Gunter Liebsch: What does normal zero mean? (pdf; 9.1 MB) Federal Agency for Cartography and Geodesy (BKG), 2009, accessed on May 30, 2013 .
  2. ↑ http://www.normaalamsterdamspeil.nl/ Stichting Normaal Amsterdams Peil
  3. ↑ Normaal Amsterdams Peil (NAP). (pdf; 0.4 MB) Gemeente Amsterdam, 2009, p. 2 , accessed on June 1, 2013 (Dutch).

Coordinates: 52 ° 22 ′ 23 "  N , 4 ° 53 ′ 34"  E