Tuesday, March 4, 2014

Monitoring the Water Level


As we left the Zuiderzee Museum on our way to Amsterdam, we had a chance to reflect in the bus about the challenges of the sea. As we learned while entering the country, the Netherlands is flat with relatively few differences in altitude. In fact, over half of the country is below sea level. Fortunately, there are dunes, dikes, and other forms of protection to make sure the Netherlands is not flooded.

To find out if the dunes and dikes are still high enough to prevent water damage, measurements are made on a regular basis of the levels of land and water. A water-level gauge is an instrument to measure the level of surface water, for example. and we've been noticing these the past couple of days.



The best-known in the Netherlands is the so-called NAP gauge (shown above on the shores of the Zuiderzee Museum), which indicates the water level in rivers, ditches, and canals in relation to the Normaal Amsterdams Peil NAP (Normal Amsterdam Level). The NAP is the level of reference to which level measurements in the Netherlands are related. A zero NAP level is equal to the average sea level.



The highest point in the country is in the province of Limburg. In the town of Vaals, where Holland, Belgium, and Germany meet, it is at 322.5 meters (1,058 feet) above NAP. The lowest point, 6.76 meters (22 feet) below NAP, is in a field in the Zuidplas Polder in the vicinity of Nieuwerkerk aan den Ijssel. In that polder, the differences in altitude are quite visible, they say.

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