Geography of the European Netherlands European part of the country can be split into two areas: the low and flat lands in the west and north, and the higher lands with minor hills in the east and south. The former, including the reclaimed polders and river deltas, make up about half of its surface area and are less than above sea level, much of it actually below sea level. An extensive range of seawalls and coastal dunes protect the Netherlands from the sea, and levees and dikes along the rivers protect against river flooding. The rest of the country is mostly flat; only in the
Flood control in the Netherlands strategy largely obsolete. Technological development in the 20th century meant that larger projects could be undertaken to further improve the safety against flooding and to reclaim large areas of land. The most important are the Zuiderzee Works and the Delta Works. By the end of the twentieth century all sea inlets have been closed off from the sea by dams and barriers. Only the Westerschelde needs to remain open for shipping access to the port of Antwerp. Plans to reclaim parts of the Wadden Sea and the Markermeer were eventually called off because of the ecological and recreational values of