[Mr. Rozendaal is the science writer for Elsevier, a Dutch weekly newsmagazine.]

Many Dutch, shocked by seeing the devastation caused in the U.S. by Hurricane Katrina, were reminded of what happened to their own country more than 50 years ago. On Feb. 1, 1953, the southwestern part of the Netherlands was struck by a flood of biblical proportions. The Dutch levee system collapsed in 500 places. There was nowhere to hide. More than 1,800 people drowned, together with tens of thousands of cattle and other animals. Some 4,000 houses were destroyed, and 40,000 severely damaged. About 100,000 people had to evacuate out of a population of around 12 million.

The Dutch had suffered catastrophic floods before, but the deluge of 1953 was a different kind. Just consider that twice as many people were killed in the flood as during the infamous German bombing of Rotterdam in 1940. The nation was stunned. Older Dutch from the southwestern islands still get tears in their eyes when they talk about how they lost loved ones during what is simply called "the disaster."

The Dutch reaction was: Never Again. The government decided to give the southwestern and most vulnerable part of the country the best possible protection. Eleven massive dams, sea walls and sluices were created in waters that sometimes look more like a sea than a river. The hydraulic wall built in the vast Oosterschelde, for instance, is 5.6 miles long and rests on 65 concrete pillars about 43 yards tall. Its sluice-gate doors are usually open to protect the special habitat (partly seawater, partly freshwater) behind it, and are only closed when floods are imminent.

Another wall, the Maeslantbarrier that completed the protection system, consists of two hollow doors -- as long as the Eiffel Tower in Paris is tall, and four times as heavy -- which are lying in docks on the banks of the Nieuwe Waterweg. In the event of extreme bad weather the docks are filled with water, and the gates float and are turned into the Nieuwe Waterweg where they seal off the river. In that way this barrier protects the city of Rotterdam and its surroundings, where about the same number of people live as did in greater New Orleans.

This complex system of dams and barriers -- called the Delta plan -- is a technological achievement comparable maybe in its complexity and ambition to the American Apollo project that put a man on the moon. After all, the Delta plan was designed to protect the Netherlands from flood conditions that happen only once every 10,000 years! New Orleans, on the other hand, was protected only against hurricanes that occur every 50 years. The total cost of the Delta plan, which began in 1953 and was only completed a couple of years ago, amounted to $5 billion....