40 years the Dutch drained nearly half a million acres of ancient seabed. Creating four new territories, the largest addition to Holland in history. [SOUND] The new northern closure dikes stood as a shining triumph of extreme engineering. And for the first time, the Dutch felt safe from the constant threat of flooding. But 90 miles to the south, disaster was growing in a marshy region where the Rhine and Meuse Rivers split into tiny branches before spilling into the North Sea. [MUSIC] During World War II, allied bombers had targeted this region to deny the Nazis an important strategic foothold. When the war ended, the dikes were in bad repair. But they were the only barrier standing between the raging North Sea and some of Holland's oldest reclaimed lands. And then on February 1st, 1953 the worst happened. 80 mile an hour winds from the North Sea began to push a mountain of water towards the weakened dikes in the South. Pounded by 60 foot waves, the dikes eventually gave way. One Village, was nearly wiped off the face of the Earth. [MUSIC] Because the first dike gave way after dark, most villagers had no way of knowing that the North Sea's attack had begun. Trapped in their homes, many fled to their attics. [MUSIC] But that was not high enough. Whole families were crushed or drowned as their houses collapsed. Nico Poortvliet was one of the lucky few who survived. >> Father had his hammer and his chisel. So when we were on the top of the house, it could make a hole in the roof so that we could get outside because he said, you will be trapped just like rats. And that was just what happened with my grandmother a few houses away. >> By daybreak the sea had demolished 70 dikes. And pushed 45 miles inland. Nearly 2,000 people perished. It would take 10 months to repair the dikes and pump out the seawater. But for some, the memory of the tragedy would endure far longer. [MUSIC] >> People who made it through, they can say no. Remember, it can always happen again. [MUSIC] >> The disaster was a major setback for the Dutch. Clearly, the dike across the was not sufficient to protect the country. Builders realized that they would have to construct another massive barrier, this time in the south. But there was a problem. The southern coast had not one, but several inlets to protect, presenting an engineering challenge far more daunting than anything builders had ever before faced. [MUSIC] In 1958, engineers devised a plan and work began. [SOUND] Over the next 30 years, engineers painstakingly built barrier after barrier, creating new inland lakes and redirecting rivers. Finally, only one opening remained. But it was the largest inlet of them all. A potential back breaker. [SOUND] The tides here surged with incredible force. [MUSIC] Even so, engineers pushed forward with a traditional dike, like the others they had just completed. [MUSIC] But just as construction began, the project took an unexpected turn. For the first time ever, the Dutch public began to question the methods employed by their heroic builders. [NOISE] Because building a dike across this inlet would have caused the destruction of a fragile ecosystem. Threatening the local fishing industry. [MUSIC] So engineers stopped building and set out to try to find a new approach, one that would protect the land without decimating the coastal fishing industry. [MUSIC] Spurred by these new demands, Dutch engineers came up with an ingenious proposal. >> It was decided to build an open structure, that would only be closed during extreme storm surges. And building in those hostile conditions, that was really difficult. At the same time, there was time pressure. So a lot of research and development had to take place during the construction phase even. >> Ahead on Extreme Engineering, can engineers hold back nature's fury? [SOUND] It would be a dam like no other because it wouldn't attempt to block the flow of water, unless a devastating storm surge threatened. [MUSIC] The proposed structure would be the world's longest dam with doors. More than 60 of them, each weighing as much as 40 fully loaded railroad boxcars, hung between 65 gargantuan piers. Under normal conditions, each door would remain in the up position, allowing the North Sea to flow underneath. But if sea levels rose to dangerous heights during a storm, the doors would be lowered to the sea floor, sealing off inland Holland from the storm surge. [SOUND] No structure this complex had ever before been built in the sea in an area with such strong tides. Builders feared that super strong currents would tear the structure apart before they could anchor it to the sea floor. Currents this strong would make the sea bottom unstable because they rip away the fine sand. >> Twice a day the water flows in and out, the high velocity and building a structure in there is quite a task. The bottom is formed of sediments, fine sediments that move around constantly. >> To better understand how the current affected the sea floor, scientists came to a laboratory like this. A technician places a measuring device into a test tank. The bottom of the tank is lined with sediment similar to those at the bottom of the North Sea inlet. The only force turning the propeller is the moving water. When the water speed increases to that of the currents in the North Sea Inlet, the sediments begin churning wildly. For Dutch designers of the southern dam The lessons were painfully clear. If they tried to build the dam directly on the floor of the inlet, the shifting sands would topple. They had to come up with another way of securing their massive dam. [MUSIC] They turned to the Zuiderzee Dike for inspiration. [MUSIC] Here, designers counter the force of the current by placing huge willow mats on the sides of the dam and on the sea floor. Could a similar technique save the southern dam? Engineers believed it could. But this time, instead of hand weaving the mats from willow branches, they constructed a huge factory on a channel island to manufacture the protective coverings on a massive scale. [MUSIC] The one foot thick mats began with a long plastic foundation which was filled with gravel and covered with another plastic sheet [MUSIC] As the factories scrambled to produce enough mat, shipyards launched three new construction vessels specially designed for the project. [MUSIC] And in a huge dry dock created on a channel island, the massive piers took shape. Each pier was a stall as an 11 story building, and weighed a whopping 18,000 tons, the same as a nuclear submarine. [MUSIC] These engineering marvels would form the backbone of the new barrier. [MUSIC] But first they have to be put on their proper places and that would be a daunting undertaking. [MUSIC] Because the tides flowing into and out of the inlet, we simply too powerful for standard construction work. But there was a brief period each day when the current could be overcome. [MUSIC] When the outgoing tide paused, before rushing back in. [MUSIC] But it was only the narrowest of windows, a mere 30 minutes. [MUSIC] That meant that engineers would have only two half hour periods a day when they could assemble the dam in the water. If they were to succeed, they would have to move with clock like precision. First, from the back of a ship, they unfurled the 100 foot wide foundation mat, which came to rest on the unstable sea floor. [MUSIC] Now, another ship maneuvered one of the huge piers into position to lower it onto the waiting mat below [MUSIC] With only 30 minutes to complete the work, there was no room for error. >> It's so difficult to place it right in the right place, just only a few centimeters away from the spot it should be, and we were lucky we did it. [MUSIC] >> Then a custom designed scooping crane placed 5 million tons of rock around the edges of the dam to anchor the mats and brace the piers against any blow. [MUSIC] Next, came an equally demanding task. Installing the huge doors, each weighing 400 tons. [MUSIC] By 1987, the storm surge barrier was complete. All 65 piers and their gates were in position for the brand new highway running along the top. [MUSIC] The most sophisticated dam ever built. It's designers are confident that it will last for 200 years. [MUSIC] [SOUND] But can it really stand up to the full force of the North Sea? >> When the big storm comes, you can imagine it's enormous, it's really enormous. When wind force 11 stands on the barrier with all these big waves, up to three, or four, or even five meters, it is an enormous power. You really must feel it. >> [SOUND] During a storm computers monitor surrounding seas. When a storm surge reaches ten feet above median sea level, an alarm goes out to the emergency control team. [SOUND] They give the command to lower the doors, sealing off the inlet. [SOUND] As of 2002, the dam has had the slam shut 21 times protecting the coast and saving countless lives. It's a victory for those who remember the terrible flood of 1953. Like Nico Portfleet, the young village boy who grew up to be current supervising engineer of the dam. >> There is a kind of special feeling, working on this barrier, you can imagine this. [MUSIC] With the completion of the southern barrier, Holland was better protected from the North Sea than ever. [MUSIC] Yet there remained one glaring gap in Holland's formidable defenses, the narrow channel that led up the Rhine River to the Port of Rotterdam. [MUSIC] The busiest sea port in the world. [MUSIC] Every six minutes another ship enters or exits the harbor. Over a year that's more than 80,000 vessels, hauling more than 320 million tons of cargo. [MUSIC] If a major storm surge were to come barreling up the Rhine, it would flood Rotterdam with more than 16 feet of water. [MUSIC] Worse still, the sea would inundate a huge area to the north, the most densely settled part of Holland, home to more than 5 million people. [MUSIC] The Dutch knew that they had to protect the strategic port no matter what the cost. [MUSIC] The problem was, no one could figure out how to design a storm barrier that wouldn't also restrict the flow of ships and goods. [MUSIC] Next up on Extreme Engineering. It's robotics to the rescue as the world's largest surge barrier is assembled. In 1991, a new generation of engineers took up the challenge. To build a storm surge barrier large enough to protect the port in an emergency, but kept out of the way until needed. [MUSIC] They came up with the revolutionary design, a pair of massive barriers that could swing into place across the river when needed, shielding the port from an approaching storm surge [MUSIC] Each barrier would be attached to the end of a massive arm of steel tubes. And each of these huge arms would have a shoulder, a ball and socket pivot that allows it to swing its barrier into place. [MUSIC] To test the design, engineers experimented with a scale model in a lab. Like the model, the actual steel barriers would be hollow, allowing them to float on the surface of the water. Once they've swung into place, They would be filled with water and sink to the bottom, sealing off Rotterdam from the approaching flood. Over all a stunningly simple design, but very difficult to build. >> The first test we did. She held tremendous instabilities of the whole structure. Simply due to the current that's going under the barrier while we bring it into position, the barrier was absolutely out of control. >> The bobbing motion of the model appears slight. But it means that the real barrier would heave up and down 30 feet. Possibly tearing the structure apart. So engineers redesigned the underside of each barrier, to try to reduce the turbulence below. But no one could know for sure if this change would be enough. [MUSIC] Finally they were ready to begin building. First, they constructed a gigantic dry dock on each side of the river. The huge chambers mirrored the curved form of the barriers [MUSIC] Then the giant steel tubes that would form the barriers' arms arrived. The largest tubes were 100 feet long and six feet in diameter, big enough for a person to stand up in. [MUSIC] Welding each joint took six days and had to be perfect. [MUSIC] Just one bad weld on a moving structure weighing 14,000 tons would be catastrophic. [MUSIC] Meanwhile in a factory in the Czech Republic, workers cast the most critical component. The two steel spheres, each 33 feet in diameter, that would form the shoulder joints for the huge steel arms. [SOUND] The finished spheres arrive by sea, suspended at the end of a massive crane. The huge sockets ready to receive them. These ball and sockets are a remarkable feat of precise engineering. They are designed to function smoothly under the 70,000 tons of pressure that a powerful storm surge can generate. [MUSIC] [SOUND] In 1997, six years and almost $3 billion after work began, Rotterdam finally had its storm surge barrier. Holland's Queen Beatrix christened the barrier, which would now get its first full test run. Would the design work or would it be ripped apart as it moved? It worked, but those waters were calm. The real test will come the first time it has to close during a massive storm. And when that time comes, the barrier will move without human help. Because the barrier is not only the largest moving object ever made, it is also the largest robot in the world. >> All the machinery started automatically by the computer, without any human interference. So in that sense, it's the largest robot. [MUSIC] >> Day in and day out, the barrier's computers stand watch over the waterway. Analyzing the latest weather and oceanographic data, searching for an approaching storm. [MUSIC] As of 2002, the barrier had not yet closed in an emergency. But that good luck may end soon, because Holland's weather is changing. Storms are growing more vicious with each passing year. Next up on Extreme Engineering, engineers look to the city of New Orleans for answers. [SOUND] The raging North Sea has forced the southern dam to lower its doors ten times more than planners had originally predicted. And if the weather continues to worsen, intense storms like those found only in the tropics could make their way to Holland. [SOUND] The heavy rains they bring could turn once friendly rivers into deadly foes, opening a brand new front in the war on water. [MUSIC] Hardest hit would be Holland's heartland, small farming villages like Ochten on the Rhine River. Like the beating of a great heart, floods have moved in and out with the seasons tracing a predictable rhythm. For centuries the dikes have protected the town and farmland during these floods. But in the winter of 1995, that pattern suddenly broke. Unusually heavy rain soaked the countryside. The water drained into the Rhine causing it to rise. The river reached its usual peak level, but then it kept going. >> The dike began to tear up, the level of the river was still here. It was a very dangerous situation. I get advised to evacuate immediately. >> It was a critical moment. The swollen river threatened to overwhelm the dikes and inundate the village. >> There would've been a wall of water destroying all the houses in a circle of about a kilometer. That would've meant for the village of Ochten, of about 3,000 people, that it would've been washed away. [MUSIC] But the flood never came. The river stopped rising and slowly receded. Was this near miss nothing more than a once in a century threat? [MUSIC] If global warming is a reality, the worst may be yet to come. [MUSIC] Our showers now will become more tropical and that means that the tropical intensities will appear here. If you travel to the south then you know that tropical showers are way more intense than our showers in the north. [MUSIC] Will increased rainfall force Holland to face a war on two fronts? Against both an angrier North Sea and flooding rivers? [MUSIC] To learn what the future may bring, some Dutch planners have looked elsewhere. To replace closer to the tropics, where engineers have been locked in a similar struggle for nearly a century. New Orleans, Louisiana. [MUSIC] This city is famous for its night clubs and casinos. But the real gamble here plays for far higher stakes. [MUSIC] The city is under siege from water on all sides, and engineers may be powerless to fend off disaster. [MUSIC] Like much of Holland, New Orleans sits on land reclaimed from water. In this case, the Mississippi River. And also like Holland, the city has been sinking over the centuries. Not only that, nearby Lake Pontchartrain crowds New Orleans from the north. Both the river and the lake are poised to pour destruction on the city below. [MUSIC] Only giant levees, similar to Holland's dikes, keep the city from being drowned. [MUSIC] But New Orleans also faces a huge danger that Holland doesn't, at least not yet, hurricanes. [SOUND] These enormous storm systems pack incredible power. >> A hurricane would be equivalent to hundreds of nuclear bombs in terms of the amount of energy released. So even if we dropped our biggest nuclear bomb on a hurricane, it wouldn't even feel it, it would just keep right on going. >> Hurricanes gather strength far out to sea. And as they approach land, they drive a wall of water before them. These storm surges can be even more destructive than the North Sea floods in Holland. In fact, the largest storm surge ever recorded A devastating wall of water 23 feet high, slammed into the Gulf Coast in 1969. Driven by the 180 mile per hour winds of Hurricane Camille, the storm surge killed 200
