IJsselmeer

The IJsselmeer (ɛisəlˈmeːr; Iselmar, Iesselmeer), also known as Lake IJssel in English, is a closed off inland bay in the central Netherlands bordering the provinces of Flevoland, North Holland and Friesland. It covers an area of with an average depth of . The river IJssel flows into the IJsselmeer. Two thousand years ago Pomponius Mela, a Roman geographer, mentioned a complex of lakes at the current location of the IJsselmeer. He called it Lacus Flevo. Over the centuries, the lake banks crumbled away due to flooding and wave action and the lake, now called the Almere, grew considerably. During the 12th and 13th centuries, storm surges and rising sea levels flooded large areas of land between the lake and the North Sea, turning the lake into a bay of the North Sea, called the Zuiderzee. The Zuiderzee continued to be a threat to the Dutch, especially when northwesterly storms funnel North Sea waters towards the English Channel, creating very high tides along the Dutch coast. During the 17th century, Zuiderzee dykes collapsed several times and plans were drawn up to eliminate the threat by draining the bay. Later drainage plans focused on creating fertile farmland, but they never progressed beyond the planning stage. It was only after the flood of 1916 that the legislature approved the Zuiderzee Works, a major hydraulic engineering project that involved building dykes, draining parts of the Zuiderzee and constructing the Afsluitdijk to keep tides and high water out. In 1932 the Zuiderzee was closed off by the Afsluitdijk, a dyke connecting Friesland and North Holland on either side of the Zuiderzee. The Zuiderzee was no longer a sea inlet and was renamed IJsselmeer (Lake IJssel). The continuing flow of fresh riverwater soon flushed out the saltwater. From 1929 till 1967, over half the IJsselmeer was drained, creating of polders: Wieringermeerpolder, Noordoostpolder, East and South Flevoland. In 1975, a dyke was built between Enkhuizen and Lelystad as the northern boundary of the Markerwaard, a planned but never realized polder in the IJsselmeer.