A dike (or dyke) is a construction built along the edge of a body of water to prevent it from flooding onto an adjacent lowland. Dikes can be permanent earthworks or emergency buildings (often of sandbags) built hastily in a flood emergency. The Zuiderzee Works (North Sea Reclamation Works) in the Netherlands are an immense series of dikes built to reclaim the area from the sea. This dike sytem goes further to the east and north via nearly the whole german coast up to Esbjerg in Denmark. The estuaries of the flatland rivers Rhine, Elbe, Ems, Weser and Eider are also protected from storm tides by dikes, which can be more than 9 m high.

The city of Richmond, British Columbia in Canada is an island of 129.666 km2 at the delta of the Fraser River. The first dykes were created by individual farmers in 1861 to reclaim land. Pumps are still used to this day to keep water out, and there are still uncovered ditches throughout much of Richmond. Many of the ditches are being replaced with pipes with sidewalks on top.

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