Dutch defy seas, but indulge rivers

Petten is a seaside village, but not one of its tidy homes, hotels, or restaurants has a view of the sea.

You can hear the seabirds and feel the cool North Sea wind, but the sea itself is hidden behind a massive sea wall, a long artificial hill 42 feet high and perhaps 50 yards thick at its base. Only by climbing the stairs to the top can you see the surf crashing against reinforced stone and concrete and appreciate how low-lying and vulnerable Petten really is.

Dutch authorities have raised the height of the Pettener Sea Wall several times since 1976, when it stood only half as tall, trying to keep ahead of storms and coastal erosion. But it may not be tall enough yet.

With half of its territory below sea level - and much of the rest threatened by coastal or river flooding - the Netherlands is taking climate change very seriously. Global warming is expected to cause the seas to rise by somewhere between four inches and three feet during this century, while increased rainfall may enhance the flood risk for low-lying towns and cities behind the Dutch sea defenses.

Unlike the United States and many other countries, there is no debate in the Netherlands over the need to take action to ensure that the country is prepared for the possible effects of rising seas, increased storms, and surging rivers. The Dutch expect to invest an extra $10 billion to $25 billion in flood and sea defenses over the next century, and are already drafting plans to upgrade dikes, pumping stations, and sea walls.

"It's better to be safe than sorry when you live below sea level," says Peter C. G. Glas, director of inland water systems at Delft Hydraulics, which designs much of the country's extensive water management infrastructure. "We've had a tradition over the past century of being frightened of the water, and rightly so."

When it comes to water management and flood protection, probably no country in the world has as much experience as the Netherlands. The Dutch have been fighting the North Sea and the Rhine and Meuse Rivers for millennia, ever since Roman-era farmers began draining marshland to plant crops.

Unfortunately, drained land tends to settle and sink with the water table, and the Dutch were soon surrounding fields and towns with dikes and canals and using wind mills to keep them pumped dry. The land has continued to sink, and much of it is below sea level. But the Netherlands has had the wealth and technology to continue building ever larger dikes, pumping stations, and sea walls.

During the last century, the Dutch sealed off the entire Zuider Sea with a huge dam that turned it into the huge freshwater Lake IJssel. Entirely new provinces were created by reclaiming parts of the sea floor with more dikes, pumps, and canals. Huge levees were built to tame the Rhine and Meuse, and enormous storm surge gates have been built at their mouths.

But as the water defenses have grown ever larger, so too have the consequences of their failure. In 1953, a storm surge smashed through the sea defenses in southern Holland and nearly 2,000 people drowned. A 1995 river flood forced the evacuation of 200,000 people and millions of animals from endangered areas. Much of the countryside would drown in the continuous rain if pumping stations didn't lift the water up, over the sea walls, and into the North Sea.

A decade ago, Dutch authorities started studying their options for dealing with not only sinking land, but rising seas, more-powerful storms, and ever-larger floods. Government engineers considered several strategies, including a plan to simply surrender large parts of the country to the sea. The most cost-effective plan was selected: strengthen the existing defenses and pumping stations, at a cost of $19 billion to $25 billion.

"These are enormous figures if you had to spend them all at once, but we're able to spread it out over 50 to 100 years" says John de Ronde of the National Institute for Coastal and Marine Management in The Hague, which prepared the estimates. "And it's relatively simple for us to cope with sea-level rise because we already have [$2.5 trillion worth of] existing infrastructure."

"If you really have to start from scratch and build all of this infrastructure, you'd probably have to consider giving the land to the sea," he says. It's a situation low-lying regions from Bangladesh and the Marshall Islands to southern Louisiana and the Florida Everglades may soon be facing.

The Dutch also plan to surrender hard-fought land to the water - not to the sea but to the Rhine and Meuse rivers, which end in the Netherlands after draining much of the land between here and the Alps. They call the plan "making room for water."

Naturally flowing rivers spread over vast flood plains every spring, leaving behind the organic material that makes these areas so fertile. As in many parts of the world, the Dutch wanted to farm and settle in those flood-prone areas. So the rivers were imprisoned between artificial levees.

But when a particularly large flood came, the surging rivers sometimes breached the levees, crashing through towns like a tidal wave. Larger levees were built, which, when breached by an even-larger flood or a winter ice jam, caused ever-greater disasters. Since global warming is expected to increase precipitation in the Rhine Valley, levees would have to be raised even higher.

"There are flood plains that are inhabited that should not be," says Jeroen van der Sommen, managing director of the Delft-based Netherlands Water Partnership. "We have to change our thinking and say, 'If you don't want to get your feet wet, you need to get out!' "

The new strategy will give the rivers more room, allowing them to flood more naturally, rather than trying to force them into artificial channels. By 2050, 222,000 acres of land will be surrendered to increase the size of the river flood plains, which will be allowed to turn into natural forests and marshland. Another 62,000 acres of pasture will be earmarked as huge temporary storage pools for floodwaters. Land use practices on another 185,000 acres of farmland will be changed so they can tolerate soggy conditions in winter and spring.

In the densely populated Netherlands, sacrificing land won't be easy. One company is designing giant floating farms, commercial parks, and towns that could be stationed in flood-storage areas. Some towns and villages will be told they can't build new infrastructure, because their surroundings will be given back to the rivers in the coming decades.