Dutch flood protection: Taming the water wolf

March 11, 2010

The Dutch flood protection system is an example of how planning, engineering expertise, and political purpose can protect people and property.

Life below sea level usually is aquatic. But the Dutch haven’t grown gills yet. Instead, they became the masters of flood protection, battling what Dutch poet Vondel called “the water wolf” for centuries, and mostly winning.

The Netherlands means ‘low countries’.  About half the nation is below sea level and two thirds is prone to flooding by the North Sea and major rivers like the Rhine and the Meuse.

The settlers of these low lands started digging drainage ditches over two thousand years ago. Since then, the land has sunk by up to five meters. Farming, industrialization, and urbanization have all weighed heavily on the naturally boggy landscape through groundwater extraction, land cultivation, and construction, leading to subsidence. These are man-made lowlands.

Perhaps that’s why the Dutch are so good at man-made solutions.

One example is the famous 'polders'. These low lying areas were once prone to flooding but are now protected by embankments, dikes, water sluices and pumping stations. 

For centuries Dutch communities have set aside their differences to fortify the polders and protect their settlements. Today, Dutch people expect their governments to maintain flood protection systems. Disasters are unacceptable.

The most spectacular of these systems—the Delta Works and Zuiderzee Works—are hailed by The American Society of Civil Engineers as one of the Seven Wonders of the Modern World.

The Delta Works closed coastal inlets and estuaries with new dams to protect the densely populated western Netherlands. The works also included barriers with sluices that could be opened in times of heavy rain and violent storms.

Damming the Zuiderzee—a dangerous North Sea inlet—with a 32 kilometer long dam protected the central Netherlands, and created 1,650 square kilometers of new polders.

Laws like the 1996 Flood Defenses Act commit any government to maintain flood defenses to pre-determined standards. These standards were set by the pivotal 1959 Delta Act, a response to the catastrophic 1953 floods that killed 1,835 people.

The “dike ring areas” that protect major cities and industrial areas must withstand a once in 10,000 year storm surge. Less populated areas are protected against once in 4,000 year floods.

These standards crystallize Dutch thinking about flood protection: better safe than sorry. Most Dutch agree that flood protection is paramount and money well spent.

Climate change and rising seas will make life below sea level more challenging. But the Dutch are confident they can cope with whatever the water wolf throws at them.

James Tulloch

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