The Netherlands and the U.K. have spent huge amounts of money for coastal flood protection that far exceeds what the U.S. had shielding New Orleans and the Gulf Coast. In coming years the two European nations plan to spend even more to cope with rising sea levels.

Prompted by catastrophic floods on either side of the North Sea in 1953, both The Netherlands and the U.K. invested heavily in coastal defenses. A major storm surge had coincided with high spring tides to raise sea levels by nearly 3 meter. Sea dikes in the southwest of The Netherlands collapsed extensively, causing nearly 2,000 deaths. In England, floods caused 300 deaths and $10 billion of damage at today's prices.

Thames Barrier protection of London, much of which lies below sea level, is at a 1-in-2,000-year protection level. (Photo: U.K. Environment Agency

The differences between Louisiana and The Netherlands are dramatic, say the Europeans. �The New Orleans event is thought to be of a magnitude that would reoccur every 50 years or so,� says a spokeswoman for the U.K. Environment Agency. �Currently protection of London, much of which lies below sea level, is at a 1-in-2,000-year protection level,� she adds.

As its main defense, the U.K. government completed the Thames Barrier in 1994 at a huge cost then of nearly $1 billion. Located downstream of London, the 520-m-long barrier has four 61-m-long rising sector gates. Protecting some 1.25 million people and around 75% of the flood risk real estate in England and Wales, the barrier and associated infrastructure was designed to be effective until 2030.

The $3-billion barrier closing the mouth of the Oosterschelde, north of Antwerp, is 3-kilometers-long and includes 62 steel gates between precast concrete piers. (Photo: Henk Steenhoven)

Since 1953, The Netherlands has spent over $10 billion on defenses, notably in the Zeeland Delta plan, ending in 1997. Its main component is the $3 billion barrier closing the mouth of the Oosterschelde, north of Antwerp. Completed at a cost of $3 billion in 1986, the 3-kilometer-long barrier includes 62 steel gates between precast concrete piers, each weighing around 18,000 tonnes.

With major rivers such as the Rhine and Meuse crossing its territory, inland flooding is another major threat to the Netherlands. With increasing flows, traditional dyke raising is no longer seen as an option, according to Rijkswaterstaat, the Dutch government department responsible for water resource management. Instead, the government aims to increase the flow capacity of rivers by measures, such as relocating dykes and creating retention areas.

For the future, the Netherlands and the U.K. forecast sea level rises in flood defense planning through the effects of global warming and long-term falling land levels caused by geological factors. High tide levels in central London are rising by some 60 centimeter each century. Dutch forecasts put the increase there at 10 to 90 cm.

In the Netherlands, various water boards manage most of the 3,500 km of primary river and coastal flood defenses protecting two thirds of the country. The Dutch Rijkswaterstaat is set to spend nearly $200 million this year for flood defenses and $3.5 billion for flood defenses over the next 15 years. Three quarters will go into increasing flood capacity of key rivers and the rest will reinforce defenses at eight �weak� spots along the coast, according to a Rijkswaterstaat spokesman.

The Environmental Agency is responsible for flood defenses in England and Wales. It spends around $1 billion a year on coast and river infrastructure, 30% up on four years ago. The agency launched studies last year, due to end in 2008, into longer-term risks and defenses, raising the possibility of an even larger barrier further downstream on the River Thames.

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