Normaal Amsterdams Peil
Encyclopedia
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
. Originally created for use in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, it was adopted by Prussia
Prussia
Prussia was a German kingdom and historic state originating out of the Duchy of Prussia and the Margraviate of Brandenburg. For centuries, the House of Hohenzollern ruled Prussia, successfully expanding its size by way of an unusually well-organized and effective army. Prussia shaped the history...
in 1879 under the name Normalnull, and in 1955 by other European countries.
Mayor Johannes Hudde of Amsterdam
Amsterdam
Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...
in a way came up with the idea after he expanded the seadike after a flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
in Amsterdam in 1675. Of course a dike should be storm-resistant to protect a city against flooding, and in this case a margin of "9 foot and 5 inch" was deemed enough to cope with rising water. So he measured the waterlevel of the adjacent sea-arm, Het IJ and compared it with the waterlevel in the canals within the city itself. He found that the water level at an average summer flood in the sea arm (when the water level reaches its maximum, not counting storms) was about the same as the level on the other side of the seadike, plus the margin of 9 foot and 5 inches. So the normal waterlevel in the canals of amsterdam - which is quite constant - called zero (normal) level Amsterdam Peil (NAP), equaled the level at summer flood at sea in the sea-inlet, which changes throughout the year. So normal does not mean average sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
in general, but it does offer a constant.
Originally the zero level of NAP was the average summer flood water level in the IJ
IJ (bay)
The IJ is a river, formerly a bay, in the Dutch province of North Holland. It is known for being Amsterdam's waterfront. The name derives from the generic Germanic term for "water" and is similar to other Aa/Ee names for bodies of water. In Dutch, the name consists of the digraph ij, which is...
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 realized by a bench mark in brass in the centre of Amsterdam, which is a popular tourist attraction.
See also
- Above mean sea levelAbove mean sea levelThe term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
- NormalhöhennullNormalhöhennullNormalhöhennull or NHN is a standard reference level, the equivalent of sea level, used in Germany to measure height....
- German reference system linked to NAP
External links
- History of NAP van der Weele, 1971, Dutch Royal Society for Sciences, Governmental Commission for Geodesy Het NAP-niveau