Polder

Polder, in the Netherlands, is land below the level of the sea or nearest river, which, originally a morass or lake, has been drained and brought under cultivation. An embankment, forming a canal of sufficient height to command a run towards the sea or river, is made, and when carried quite round, as in the case of the Haarlem Lake, it is called the Ringvaart. At one or more points on the embankment apparatus for lifting water is placed, and worked by wind or steam power. If the lake deepens towards the centre, several embankments and canals are necessary, the one within the other, formed at different levels as the water-surface becomes lessened, a connection being maintained with the outer canal, which secures a run for the drainage water. In the Schermer polder in North Holland are four canal levels, the land between forming long parallelograms. The water from the inner space is lifted into the first canal; that again, with the drainage of the second section, is thrown into the second, and so on until the outer canal is reached, and a fall obtained. The polders in the Netherlands are very numerous, the most important being the Haarlem Lake (q.v.), possibly to be surpassed by that of the Zuider Zee (q.v.). See also HOLLAND, Vol. V. p. 739.