A special “dike with doors” prevents flooding and simultaneously preserves the ecology of the Eastern Scheldt Delta.

Problem Overview:

A basic fact of life for peoples who live on the edge of the sea is that if the altitude of the land you live on is near, at, or below sea level, you live in danger of floods. Perhaps nowhere in the world is this danger more apparent and compelling than in Holland. One-third of the modern Netherlands lies below sea level. Much of this low-lying land abuts the North Sea, a body of water that supports Holland’s great shipping and fishing industries but also represents, in times of storms of high seas, a threat to the lives and livelihoods of the Dutch people.

By the middle of the twentieth century, most of Holland’s North Sea coast had been fortified by dikes and sea walls. Only the southwesternmost stretch of coast remained unprotected – an area that spanned the deltas of three great rivers – the Rhine, the Maas, and the Scheldt. In the early 1950’s, a great flood in the southwest Netherlands claimed over 1800 lives and left three hundred thousand people homeless. Beyond great tragedies such as the flood of 1953, each flood, including the smaller ones that did not threaten human life, would deposit salt water on the tracts of low-lying, reclaimed farmland – call "polders" – and this would damage crops and curtail growing for several years thereafter.

After the flood of 1953 the Dutch began to lay plans for the "Delta Project", a series of dikes and dams that would complete the North Sea fortifications. By the middle 1960’s, the Eastern Scheldt Delta was the last unprotected estuary in the area covered by the Delta Project, and construction was ready to being on this final link. A small number of Dutch citizens by then had come to be concerned with what they had seen of the environmental effects of the dams and dikes built in the first part of the Project. By creating a wall between the salt water of the sea, and the fresh water of the river deltas, these barriers had disturbed and largely destroyed the tidal ecologies of their respective estuaries.

A tidal zone is a complex ecosystem made up of tidal channels, mud flats, shoals, salt marshes and ponds. Each of these niches has its own characteristic temperature and salinity, subject to daily and seasonal rhythms, and each supports its own forms of life. In the Eastern Scheldt Delta, hundreds of species of algae, plankton, and water plants thrive on the mix of carbon from the sea and nitrogen and phosphorus from the rivers. These simpler life forms nourish the profusion of fish and shellfish that make the estuary their home for all or part of the year, and the fish and shellfish in turn draw many thousands of birds to the area. The Eastern Scheldt Delta is one of the three most important wintering grounds for birds in Europe. The closing off of the Delta would mean fewer birds as far away as Canada and Siberia.

Preservation of tidal ecology with respect for human safety

Background:

It was a combination of political will and technological ingenuity that eventually created a way for the Dutch people to meet the needs both of safety and of the environment.

The political will expressed itself in the dedication and perseverance of the small citizens’ groups and of the handful of members of the Dutch Parliament, including Jan Terlouw, who joined with these citizens. They were helped in their efforts when they came to see that in addition to issues of ecology and of safety there were matters of economy and of quality of life. The loss of the Eastern Scheldt tidal environment would haver dealt a blow to the area’s fishing, shellfishing, and tourism industries, both to those who earned a living from those activities and to the many more who reaped their benefits. The effort to preserve the Delta gained momentum when representative of those interests joined those whose initial concern was the environment alone. Although it is often argued that economic and ecological concerns are inevitably at odds, that is simply not the case, and the Eastern Scheldt story is one piece of evidence that it is not.

The technological piece of the solution was founded on a simple observation: it is only intermittently that storms create the threat of floods. In fact, the kind of floods that threaten the North Sea coast of the Netherlands are called "storm surges". If a dike could be designed that would be shut only when there was a threat of a storm surge, and would otherwise be open, the tides would continue to come and go and the Delta’s ecology would remain essentially intact. Safety, environment, and economy would be protected.

Engineers began work on a so-called "dike with doors" that would meet this specification. Once the design was done, its proponents set out to convince the Dutch people that the extra cost of the "dike with doors" was worth taking on. Eventually they succeeded.

Sixty-six giant towers, with steel gates between them, now stretch across 5.6 miles of seabed. Although the new design doubled the cost of a conventional dike, it successfully protects the tidal environment. Moreover, the economic activity, such as fishing and tourism, that continue to thrive help offset the higher price.

Today the Eastern Scheldt Storm-Surge Barrier is one of the world’s hydro-technological wonders. It is a testament of technological ingenuity, to commitment and perseverance on the part of a small number of people, and to the willingness of the people of the Netherlands to pay a little extra for something with so many important benefits for them and their environment.

This project is documented in HORIZON International's film "One Second Before Sunrise", Program 2

The television program is available for viewing and downloading at http://www.horizoninternationaltv.org/.

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HORIZON