Before the Levees Break: A Plan to Save the Netherlands
By David Wolman, Wired Magazine 17.01, 12.22.08
Rotterdam, Europe's busiest port, lies mostly below sea level. Photo: Ralph Hargarten
On a late fall afternoon on the western edge of the Netherlands, coastal engineer Marcel Stivestands atop a 40-foot dune. He stares out beyond the posse of wet-suit-clad surfers wading into the breakers of the North Sea. Where the surfers see inviting waves, Stive sees dry land—and a distant storm. He points south toward Rotterdam, Europe's busiest port. Arm outstretched, Stive rotates 180 degrees to face the shoreline running north. "As far as you can see, in both directions, we're going to push the coast out 3, maybe 4, kilometers," he says. "We have to—to keep the water out."
The dunes here alongside the village of Ter Heijde are among the weakest links in the complex network of natural barriers, dams, levees, canals, pumps, and storm-surge barricades that keep this lowest of low countries dry. More than half of the Netherlands sits below sea level, and if a megastorm were to break through these not-so-formidable dunes, the water could inundate Rotterdam and surrounding cities within 24 hours, flooding thousands of square miles, paralyzing the nation's economy, and devastating an area inhabited by more than 2 million people.
Global warming is a cause for serious concern in low-lying countries. The Dutch aren't waiting for a catastrophe; they're taking measures to solve the problem now.
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Stive is part of a Dutch team charged with reducing that risk. Narrowing the gap between the Netherlands and North America by a couple of miles would be a start, and as a bonus it would create valuable new real estate for recreation and development. Also on the drawing board are massive new storm-surge barriers and reinforcements around cities like Rotterdam and Dordrecht, built on the marshy delta where the Rhine and Meuse rivers meet the sea. "If you see a certain future, you must react," Stive says. And as he sees it, that future looks wet.
More than half of the Netherlands sits below sea level, and if a massive storm were to break through the dunes, Rotterdam would be inundated in 24 hours. Photo: Ralph Hargarten
Yet the chance of a breach at Ter Heijde is actually quite low, about 1 in 10,000 in any given year. (In the lingo of storm protection, that's known as a 10,000-year flood.) The coastline and river deltas of the Netherlands are arguably the best-protected lowlands in the world, and the Dutch are a little miffed at Al Gore for suggesting inAn Inconvenient Truth that their homeland is as vulnerable to rising seas as far less protected places like Bangladesh and Florida.
To Stive and other sea-rise hawks, however, 1 in 10,000 has become too risky. They want to crank up defenses in some critical areas to the level of 1 in 100,000. "To understand risk, you must consider the value of what would be lost," says Stive, a pink-faced man of 57 years who heads the coastal engineering and water research centers at Delft University of Technology, just north of Rotterdam. The half of the country that is below sea level—including the area behind these dunes—generates about 65 percent of its GDP. That's nearly $450 billion a year.
A deadly flood hit the Netherlands in 1953, covering more than 600 square miles and killing more than 1,800 people. Photos: Getty Images
There is, of course, another factor to take into account: Global warming is increasing the odds of a catastrophic breach. That means the risk calculations need revamping. New projections of sea-level rise and other potential consequences of climate change, coupled with the aftershock from Hurricane Katrina, have prompted Dutch officials to ask a very big question: What would it take to climate-proof our country for the next 200 years?
In 2007, the parliament assigned a team of experts, dubbed the Delta Committee, to come up with an answer. The group's final report, published in September, proposes a combination of aggressive new steps—extending the coastline and building surge barriers—and time-tested strategies like fortifying levees. The cost: about $1.5 billion a year for the next 100 years.
Of course, a 200-year plan seems absurd. Two centuries ago, it would have been impossible to predict how civilization and the planet would look today. But the Dutch insist that the project is prudent and rational. If they start now, the costs will be minimized and disaster, perhaps, averted. After centuries of damming, pumping, barricading, and redirecting water, the Dutch water masters are laying the foundations for what may be the most ambitious act of territorial defense in history. In so doing, they are giving engineers and urban planners from New Orleans to Singapore a preview of what it will take to keep rising waters at bay. "We have the safest river delta in the world," Stive says. And, he adds, they want to keep it that way: "We will completely control the water."
Floods may be among today's more ominous climate-driven hazards, but the Dutch know better than anyone that they're nothing new. Below a bridge crowded with bicycles in the groovy Amsterdam neighborhood of Jordan, canal boats full of beer-soaked vacationers glide past a heavy black gate. On the side of the bridge is a small block of white marble, high above the waterline, with a horizontal cut across the middle. It shows the high-water mark of 1682 and is accompanied by an inscription reading, Zee dyks hooghte zynde negen voet vyf duym voven stadtspeyl.Translation: The sea dike level is 9 feet 5 thumbs above city level.
The 327-year-old gauge is high and dry today because in 1932 Amsterdam's labyrinth of canals was sealed off from the ocean by the 19-mile-long Afsluitdijk (Enclosure Dam). That feat of engineering created Lake Ijssel, one of the largest freshwater lakes in Europe. It also cut Amsterdam off from tidal changes and storm surges, permanently lowering the city's waterline.
The Dutch have laid out a 200-year plan to defend against rising sea levels. Here's a look at the major upgrades. — David Wolman
How to Climate-Proof a Country
1 // Raise the Lake
At low tide, the North Sea now drops far enough that gravity can drain excess water from Lake Ijssel. But that won't work if the oceans rise. The plan: build up the height of the lake's enclosure and raise the water surface by up to 5 feet.
2 // Extend the Coast
To fend off swelling seas and raging storms, engineers want to push the coastline out by as much as 2.5 miles. Dredging ships would suck up ocean sand and dump it on the edge of the beach, adding 400 square miles to the country.
3 // Dam the Waters
Rotterdam, Europe's busiest port, is already protected by an extensive network of dams, dikes, and dunes. The new plan would augment that system, raising the height of existing structures and adding four giant flood barriers.
Infographic: The Department for Information Design at Copenhagen
Some 3 billion people—at least half the world's population—live in coastal areas vulnerable to the worst effects of global warming: harsher storms, rising sea levels, flooded deltas in winter, parched deltas in summer, and less sensational but equally serious problems like salt water infiltration of underground aquifers. By 2025, when the human population reaches 8.5 billion, the number of coastal dwellers is expected to be closer to 6 billion.
Marcel Stive, coastal engineer for the Delta Committee Photo: Ralph Hargarten
Success in holding back the sea has earned the Dutch an international reputation as experts in reclamation and flood protection. But that knowledge has been acquired through painful experience. In February 1953, a massive storm surge inundated 600 to 800 square miles of the country, killing 1,835 people. After the disaster, the government devised a plan so that the people of the Netherlands could confidently say: never again.
The initiative triggered a 30-year campaign of bulwark construction, known as the Delta Works, to reduce the country's flood vulnerabilities. Dams and levees were built to cut tidal areas off from the open ocean, shortening the exposed coastline by nearly 450 miles. The flagship projects are the 22-year-old Oosterschelde storm-surge barrier and the 11-year-old Maeslant barrier, a gate made up of two giant arms, each nearly the size of the Eiffel Tower. In the event of calamity-level storm waters, the barrier will close off the mouth of the New Waterway leading into Rotterdam.
The megastructures are impressive, but what may prove to be the most visionary aspect of the Delta Works is the statistical approach that guided the designs. How high should we build the levees? How strong should a surge barrier be? The Dutch decided to base their answers to these questions not merely on the fact that storms are destructive and the Netherlands low, but also on economics. With the help of renowned Dutch mathematician David van Dantzig, the 1953 task force calculated safety levels using an equation that is now seared into the minds of Dutch engineers:
risk = (probability of failure) x (projected cost of damage)
This kind of risk analysis is common today in fields like nuclear power, aerospace, and chemical manufacturing. But back in the 1950s, accounting for the projected cost of damage when developing flood protection was novel. The power of this simple formula is that it produces economically rational public-safety decisions: Less value, less protection. Dutch law now requires this principle to be used to determine the strength of flood defenses throughout the country. Since the dunes at Ter Heijde sit between the sea and a vulnerable but economically vibrant area, a safety level of 1:100,000 is called for. More rural parts of the country require safety levels of just 1:1,250 or lower.
In a Rotterdam office built atop a levee on the New Meuse river, Cees Veerman is sketching lines on a map of the Netherlands. A farmer-economist-politician, Veerman is the head of the new Delta Committee. He was only 4 years old the night of the 1953 flood, but he remembers his grandfather racing into the kitchen to grab a knife. "He was about to run out and cut the cattle loose and move them to higher ground," Veerman recalls. The townspeople in his South Holland village of Nieuw-Beijerland assumed the storm waters would rise gradually. Instead, a wall of water bulldozed through the dikes. Their lives were in danger, but there was little to do except pray. Suddenly, the water level began to drop—their prayers had been answered. "Everyone was shouting, 'The water is falling!'" It wasn't a miracle, though; the water had merely barreled through the far-side levees, relieving the buildup at the Veerman family farm while inundating areas farther inland.
To climate-proof the Netherlands for the next two centuries, Veerman and his team first needed to gather the best possible data. Most existing projections of sea-level rise look at the oceans as a whole, not at specific regions. So the Dutch commissioned their own forecasts. Developed by some of the engineers and ocean experts on the Intergovernmental Panel on Climate Change (the group that shared the 2007 Nobel Peace Prize with Al Gore), the models predict that the North Sea will rise 40 centimeters by 2050, between 65 centimeters and 1.3 meters by 2100, and up to 4 meters by 2200.
Veerman talks about Dutch can-do the way generals talk about staying the course in a prolonged military battle. "People say sea-level rise will push us back into the hinterlands," he says. "We say no, we can manage with 1, 2, even 3 meters. But we have to act." With a black pen, he inks in an expanded coastline on the map laid out before him. Extending the country westward will be a colossal reclamation effort: Dredging ships, working just offshore, would spend the next century vacuuming up roughly 121 million cubic meters of seafloor sand every year and spraying it toward the shoreline, where wave action would then deposit it at the water's edge and "naturally" build the beach outward. Over the course of 100 years, the project would add about 400 square miles to the Netherlands—roughly equivalent to 17 Manhattans.
Next, Veerman sketches in future storm-surge barriers, adds a new channel for diverting the flow of the Lek River, and draws a line connecting a small chain of islands off the northern coast that may someday be linked up to form a giant buffer against the North Sea. He also circles a swatch of farmland near the confluence of the Rhine and Meuse rivers. Global warming doesn't just bring a threat from the ocean; greater precipitation in the Alps is expected to increase the amount of water flowing through Europe's major rivers, raising the flood hazard from within. Veerman explains how this circled area will be converted back into wetlands, giving the rivers room to flood in a place that makes sense—not downtown Rotterdam.
Then he brings his pen north to Amsterdam. At present, when water levels in nearby Lake Ijssel get too high, water managers release the excess through the Enclosure Dam and into the sea. Gravity is currently able to move the water during periods of low tide, when sea level falls below that of the lake. But that will stop working as the ocean rises. One option is to pump the water out, but the expense would be prohibitive. Instead, Veerman wants to raise the level of the lake on pace with the sea, as much as 5 feet by 2100.
From the air, you can see why this would be a bitter pill for Amsterdam's booming satellite towns—especially the posh developments along the lakeshore, which would have to be fortified by higher dikes. But the price tag on the proposed lake project, as much as $8.2 billion over the next 100 years, is only a fraction of what it would cost to build and run a pump system or to repair damages if the lake overflowed into 10,000 living rooms.
Today, life around the periphery of Lake Ijssel—and throughout the Netherlands—looks so peaceful, it's hard to envision disaster. Because of that, protests seem inevitable. Environmentalists will no doubt be hostile to the idea of a century-long dredging project, relocated farmers will put up a fight, and condominium owners around the lake may resist anything that interferes with their views. But Veerman and his colleagues are convinced that bold measures now are necessary to prevent calamity tomorrow.
The wind rips through the dark skies above New Orleans. Hurricane Ike is hours from making landfall at Galveston, Texas. New Orleans should receive only a glancing blow, but residents are hardly at ease: Tropical storm and tornado warnings are expected to last through much of this September afternoon and evening. Just two weeks ago, Hurricane Gustav forced an evacuation of 2 million people and pushed the city's unfinished levee system to the brink.
On the east side of the Inner Harbor Navigation Canal,Mathijs van Ledden climbs a muddied slope toward a recently constructed flood wall. Behind him are the devastated blocks of the Lower Ninth Ward, an eerie mixture of abandoned lots, weed-covered foundations, and a few refurbished or newly built houses.
The canal connects the Mississippi River to the Gulf Intracoastal Waterway and Lake Pontchartrain. The flood wall was built soon after Katrina, to plug what was one of the most catastrophic failure points along the city's roughly 350-mile network of levees and floodwalls. Van Ledden, an engineer with the Dutch consulting firm Haskoning, has been in New Orleans since 2006. His job: Run wave and water models for the US Army Corps of Engineers to help determine the necessary height of new defenses.
Shouting over the wind, Van Ledden, 33, says a stormy day is ideal for touring the city's flood-protection maze. He leans over an older flood wall that runs perpendicular to the new, higher one. Ike has raised the water level in this canal 5 or 6 feet above normal. "During Gustav, the level was all the way up to here," Van Ledden says, placing his hand just below the top of the wall. "And Gustav was just a friendly wake-up call. In 50 years, if the sea level goes up 1 or 1½ feet, the level for that storm would be here," he says, holding his hand well above the top of the flood wall. To make sure that doesn't happen, the Corps is planning to build a giant storm-surge barrier between Lake Borgne and the Gulf Intracoastal Waterway. The barrier's gates would close during extreme storms, blocking lake water from funneling up into this narrow canal.
After Katrina, Congress ordered the Corps to bring the city's hurricane protection system up to 1:100 levels by 2011. If a 1 percent per year chance of system failure sounds high—compared with existing 1:10,000 defenses in the Netherlands—that's because it is. "One-hundred-year protection is quite a risk," Van Ledden says. Statisticians will tell you that over the course of a 30-year mortgage, the chance of a 100-year flood hitting the city is more than 25 percent. The 1:100 standard takes projected sea-level rise into account, but not economic impacts and repair costs. (Hurricane Katrina caused upwards of $150 billion in damage.)
Cees Veerman, head of the Delta Committee Photo: Ralph Hargarten
So why don't we do it like the Dutch? The glib answer is that we should. Van Ledden and colleagues have run the numbers for New Orleans, and he says investment in a protection level of at least 1:1,000 is economically justifiable in some areas. That is, the cost of boosting protections to that degree is modest in relation to the huge reduction in risk. And if you settle for mediocre defenses and they get wiped out, you also lose your initial expenditure.
But the Dutch model may not work in the US. That's partly because our hurricanes are so severe. Consider this: The levee height required for 1:100 protection in some areas of New Orleans is roughly 30 feet—the same height as fortifications in the Netherlands that provide 1:10,000 protection.
In any case, American politicians could never get away with basing flood barrier specs on the value of what sits behind them. Ratcheting up defense levels in New Orleans to match those in the Netherlands would lead other areas of the Gulf Coast to demand equal treatment. And what about earthquake zones in California, floodplains in Iowa and Missouri, or blizzard territory in New England? Should similar standards be applied there?
Van Ledden says many Dutch citizens may not know it, but their government has accepted—even legislated—unequal protection, or what engineers euphemistically call "differentiation." Everyone knows that all places can't be protected up to the same standard; individual cost must be balanced against collective cost, he says.
The US certainly has variable protection levels throughout the country, but there's a difference between de facto disparity and an explicit government policy of inequality. Imagine if Congress or the Army Corps were to recommend protecting the French Quarter and downtown New Orleans at the 10,000-year level while giving less economically productive areas such as St. Bernard Parish only a 100-year level of protection. Applying the Dutch model of risk-based design would be a political nonstarter, if not unconstitutional, and the efforts of the Army Corps of Engineers would in no time be halted by an army of lawyers.
Meanwhile, the water keeps coming. The Dutch are taking on the threat of global warming before anyone's feet are wet. They're showing the world that to prepare for sea-level rise and other impacts of climate change, you need, paradoxically, not dominion-over-nature bravado but patience, good data, and—above all—the long view.
Contributing editor David Wolman (david@david-wolman.com)
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