December's deadly tsunami in the Indian Ocean drove home how vulnerable low coastal areas are to the forces of nature. In the Netherlands, which carved itself out of the ocean centuries ago—and a quarter of whose land mass is below sea level, while two-thirds is vulnerable to flooding—the mastery of coastal waters remains the object of much technological innovation.

The Dutch acquired their hydraulic expertise partly in response to disaster. In 1953, a number of sea dikes in the southwestern part of the country gave way under a tidal surge. The disaster, which killed about 1,800 people, spurred one of the largest hydraulic projects in the country's history: the Delta Works. Almost all of the inlets and estuaries in the southwestern part of the country were closed off by a system of dams and storm surge barriers. One of the two main arteries remaining open—the estuary near Rotterdam—was fitted with the most massive movable storm surge barrier ever built. Known as the Maeslant Barrier, it has an automated control system that closes its giant doors based on real-time weather information, which can indicate the ­approach of a spring tide. The system's software borrows from a branch of ­mathe­matics called formal methods; its performance is continually monitored, and improvements are made as knowledge of weather behavior progresses.