Delta Works
In 1953 a break in the dikes and seawalls in the Netherlands killed 1,835 people and forced the evacuation of 70,000 more. Ten thousand animals drowned, and 4,500 buildings were destroyed. To prevent such a tragedy from happening again, an ambitious flood defense system was conceived and deployed, called the Delta Works (Dutch: Deltawerken).
This project was intended to improve the safety of the lower areas of the Netherlands against severe storms and flooding; since more than half of the nation's land lies below sea level, this is no simple task. Dunes along the entire seashore were raised by as much as 5 meters, while the islands in Zeeland province were joined together by dams and other large scale constructions. The most sophisticated and famous of these dams is the Oosterscheldedam (left of the leftmost "i" on the satellite image), which can be opened and closed to keep the sea at bay while preserving the saltwater river delta for wildlife and the fishing industry.
The Oosterscheldedam is sometimes referred to as the eighth wonder of the world, and has been declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers.
See also: Zuiderzee Works.