The need of new territory has pushed water engineers to design new technology to create or preserve land. On the one side, cutting-edge technology has been design to dry marshes or to protect cities from flood, like Venice. But water is also behind or the object of other great technical challenges: how do we use it to create enough energy? How do we build canals and locks to make transportation more convenient, faster and safer?
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00:00Man's ambition to tame water has led to some incredible construction projects.
00:11Dams, canals and even polders to reclaim huge tracts of land from the sea.
00:22Frederick Restaño is a physicist, an expert in fluid dynamics and a researcher at the CNRS.
00:28He's going to take a look at the work of engineers who have marked our planet's history.
00:33Every single day there was something to resolve.
00:36Now when you look back you're like, wow, we overcome a lot, but you learn.
00:44These visionaries tackled immense projects to protect themselves from the often devastating effects of water.
00:51Everything had to be invented. Nowhere in the world had a structure like this ever been built.
00:58And also to harness its tremendous power.
01:04Our scientific investigation will help understand how these extraordinary technical challenges have redrawn the landscapes of the planet.
01:11It's the story of tenacious engineers who in just a few centuries became the masters of water.
01:16What?
01:34It was here in Corinth almost 3000 years ago that the idea of building a major canal was
01:58first mooted.
02:01The Corinth Canal.
02:06Viewed from the sky, it's a trench of more than 6 km long, a line between two seas,
02:12a spectacular etching of man's desire to master time.
02:18It's a godsend for the 11,000 boats that use the Corinth Canal each year.
02:23This rocky corridor, dug into the narrow strip of land, known as an isthmus,
02:28avoids a 400 km detour around the Peloponnese.
02:33After the failure of projects dating back to Greek and Roman antiquity,
02:37the idea of the Corinth Canal fell by the wayside for almost 2,000 years.
02:41But the development of shipping traffic and world trade in the 19th century
02:45reawaken the ambitions of the Greek people.
02:48The governor decided that he wanted Greece to develop.
02:52The opening of the Suez Canal in 1869 was another ringing bell for Greece to move forward.
03:01And, well, the works began in 1882 after quite an ordeal with studies, financial issues.
03:10How much earth and rock would need to be dug out to produce a trench like this between the Peloponnese and Greece?
03:17That's more than 12 million cubic metres of earth that has been excavated here.
03:22And we're talking more than 2,000 workers that were involved in the project.
03:26Also, dynamite and nitroglycerine was one of the first projects of construction, like the canal, that has been used here.
03:35But nitroglycerine is really dangerous.
03:37It is, but they've tried it. So you can see the results.
03:42The maritime canal was completed in just 10 years.
03:47The Corinth Canal's simple construction is called a sea-level canal,
03:51meaning that it's hewn out at the level of the two seas it connects,
03:54which feed it constantly with saltwater.
04:00The technical challenge becomes much greater when fluvial channels have to be bored over long distances.
04:05Rivers and watercourses must be diverted to supply these artificial channels with fresh water
04:10and force them through the landscape.
04:14How to guide a ship up a significant gradient?
04:20In the 16th century, an invention came along that revolutionised the science of canals.
04:25The lock.
04:30In addition to its emblematic river, the Seine, since the 19th century Paris has boasted three lock canals
04:36with a total length of 130 kilometers.
04:40The Canal Saint Denis, the Canal de l'Orque, and the shortest but most famous, the Canal Saint Martin.
04:53Its nine locks allow boats to travel in both directions
04:55and negotiate an elevation of almost 26 meters between the artificial watercourse and the river.
05:01The waterfall at each of these locks is something like three meters or one storey.
05:08Each lock acts like a boat lift.
05:11When a boat takes a reach and enters the lock chamber,
05:17a set of mitre gates form an angle pointing upstream,
05:21so that the water tends to close the gates and divert the pressure onto the banks.
05:25Once closed, the lock is then emptied downstream to the lower level,
05:33thanks to a paddle, a small sliding hatch on the gate of the lock that acts as a valve.
05:42Its role is to fill or empty the lock to balance the water level,
05:46and therefore the pressure on each side of the gate to facilitate opening.
05:49Initially built of modest size to facilitate irrigation in the 19th century,
05:56the development of large canals became vital for both national and international trade
06:02by reducing the distances travelled in transporting goods.
06:06Huge projects began to see the light of day, such as the Suez Canal and the Panama Canal.
06:13The man behind both of these humongous projects was the very knowledgeable Ferdinand de Lesseps.
06:26The construction of the Suez Canal began in 1859.
06:30Plans drawn up by the ambitious de Lesseps involved digging a 162km trench through the desert
06:36to connect Europe with Asia without bypassing Africa and the treacherous seas of the Cape of Good Hope.
06:43Tens of thousands of Egyptian labourers began the work by hand.
06:48Excavators and pickaxes were replaced a few years later by dredging machines.
06:54Such inventions resulting from the advent of steam significantly reduced the need for manpower.
06:58On November 17, 1869, the new waterway was solemnly opened.
07:07The channel was admired by the whole world.
07:12For its creator, the canal's completion was a crowning glory.
07:21Ferdinand de Lesseps achieved a level of glory which is unimaginable today.
07:25He went on to tackle international relations and the construction of the Statue of Liberty.
07:34Although he wasn't a writer, he was even invited to join the Académie Française.
07:40His success led to his skills being somewhat overestimated.
07:44And de Lesseps was convinced that he was the best man to oversee the construction of the Panama Canal.
07:50This project, though, proved to be a far more complex one.
08:03Frederic Ristagno went to Panama to trace the nightmarish story of the construction of this canal.
08:08This small Central American country, a strip of 725 kilometres of land between Latin America and North America, separates the Atlantic from the Pacific.
08:19In the narrowest area of the isthmus, covered by dense, humid jungle, the man known as the Great Frenchman embarked upon the construction of his new inter-oceanic maritime canal.
08:33But the diplomat, blinded by glory, underestimated the climatic, geological and economic hurdles that would have to be overcome.
08:43And despite the reluctance of certain advisers, work began in 1882.
08:47As well as discovering a dense tropical forest flooded by torrential rains, workers faced another major difficulty.
08:59A mountainous area, the Culebra, which rises to 95 metres above sea level.
09:04They had the geography figured out, but not the geology.
09:11They thought they could carve their way through the mountain, a little like the Corinth Canal.
09:17This turned out to be very crumbly rock, and digging it triggered landslides.
09:23And those landslides, facilitated by the heavy rains, destroyed all the sites.
09:28So they kept having to start again. It really was a Sisyphean task.
09:36Before long, the workers were suffering from unfamiliar diseases.
09:39The truth was that the area was infested with mosquitoes, carrying yellow fever and malaria.
09:45Death was cutting them down, one by one, under the helpless gaze of the doctors.
09:50Back then, physicians simply didn't have the scientific knowledge to fight these diseases.
09:54As an example, they thought that putting a basin of water at the foot of the bed prevented ants from climbing up to the patient.
10:09What actually happened was that the mosquitoes were laying their eggs in the water.
10:17So hospitals were propagating the diseases they were trying to fight.
10:29Tens of thousands of workers died. It was a major factor in Ferdinand de Lesseps' downfall.
10:35Unable to stem the epidemic, the entrepreneur agreed to review his project.
10:47Backed by Gustave Eiffel, he adopted the solution of a canal with locks, better suited to the landscape of the region.
10:55But the turnaround changed nothing.
10:58After seven years, a billion francs had been squandered, with very little to show.
11:02On February the 4th, 1889, the company went bankrupt.
11:06When the Panama scandal broke, 85,000 small investors were left penniless.
11:13Now 88 years old, the illustrious de Lesseps was found guilty, and only his advanced age spared him a five-year prison term.
11:24While the French licked their wounds, the Americans began their move to gain the upper hand in the region.
11:32Theodore Roosevelt wanted the canal, regarding it as the centrepiece of a future world empire.
11:38The United States thus redeemed the French concession, making the area around the canal US territory.
11:45The first priority of Roosevelt's men was to tackle the health issues.
11:54In 1903, before continuing the construction work, more than a year was spent killing all the mosquitoes in Panama.
12:02Because in the meantime, it had been discovered that yellow fever and malaria were carried by mosquitoes.
12:12The US president then entrusted his army with the mission of finishing one of the largest engineering projects of all time.
12:22Confronted with the same geological difficulties as their predecessors, the Americans took up the aborted French idea of building a canal with locks.
12:32To supply them with water, they created a dam on the Rio Chagas, flooding a good part of the area and producing a huge artificial lake.
12:43Lake Gatun.
12:49Located 26 metres above sea level, it allowed the isthmus to be crossed without having to excavate the mountain.
12:56Access was by two sets of locks, each of a size to match the scale of the project.
13:01Boasting 25 metre high gates and 320 metre long locks.
13:05To stabilise the ships during the passage, an innovative system of locomotives acted as tugs.
13:22On August the 15th, 1914, after a 30-year construction project that claimed the lives of 27,000 men,
13:28the gates to this new inter-oceanic highway were opened.
13:34The 77 kilometre canal connecting the Pacific and Atlantic was regarded as the fourth wonder of the world.
13:43The voyage from San Francisco to New York, previously 22,500 kilometres, was now only 9,500 kilometres.
13:51While Europe went to war, the young American nation became the world's leading military power and seized control of the region.
13:58More than 100 years after the first ship sailed along the canal, Panama entered a new era.
14:08On January the 1st, 2000, after some tough negotiations with the USA, the country took over the canal zone.
14:15A forest of skyscrapers has grown around old Panama City, which is now a major financial centre.
14:23For the canal, such commercial success is nothing new.
14:28Together with its associated activities, it represents 40% of the country's economy.
14:32Now the Solmaster's in charge.
14:41The Panamanians recently carried out some major works to provide cargo ships with a brand new canal with locks.
14:46It's incredible.
14:47It's incredible.
14:59The Titanic project was supervised by Ilia Marotta.
15:14This Panamanian engineer has dedicated nine years of her life to the canal.
15:20We needed new locks because the shipping industry was getting bigger.
15:24The vessels were getting bigger and bigger and bigger and we were maxed out.
15:28So we needed more capacity for more vessels and then we needed to attract bigger vessels that couldn't fit through the existing Panama Canal.
15:34Otherwise, we would lose market share and we wouldn't be a world canal.
15:41Which lock size did you choose?
15:44So, the width is 55 metres.
15:47And the length of this chamber is 427 metres.
15:53And the biggest vessel we can put in is 366 metres in length.
15:57And so far, a 49.5 metre vessel can come in.
16:01The amazing thing is that it means that you can now fit an Eiffel Tower lengthways in the locks.
16:08Actually, we could have built 19 Eiffel Towers with the amount of steel that was used to reinforce these concrete walls.
16:1719 of them.
16:18So, it's a pretty big project.
16:20Yes, it's a gigantic project.
16:24This new project began in January 2007.
16:26Responding to competition from the Suez Canal, Panama is expanding its shipping channels, transforming the legendary Culebra into a giant minefield.
16:38The biggest challenge, though, lay in the construction of a third set of locks to accommodate even larger ships.
16:52The new reinforced concrete chambers have 16 sliding gates, each over 57 metres high.
17:05After nine years of work, Panama opened its new locks, tripling the capacity of cargo ships, which can now embark nearly 14,000 containers.
17:13What did you include in the specifications when you decided to build the new locks?
17:20In the old locks, we have locomotives, which help position the vessel in the middle of the chamber.
17:29Here, we did not use locomotives. Why? Because it was too expensive. The walls would have to have been heavier to sustain the weight of the locomotives. More equipment, more people. Also, the locomotives and the cables would have to be too big for these type vessels.
17:48Other than that, the gates, they're very different.
17:51The engineers decided on an innovation, replacing miter gates with sliding ones.
17:59The gates range from 2,400 tonnes to 4,200 tonnes.
18:04But only 15% of the weight is what gets moved with the motors. 85% of it is floating.
18:13Because each gate has a floating compartment that allows the gate to be like a ship, so it's not that heavy to move it.
18:19Basically, you can't mess with Archimedes' principle.
18:22Yes.
18:24The last challenge of this project was to preserve the water of Lake Getun, which supplies the canal and its locks.
18:31Each giant container vessel passing through drives no less than 197 million litres of water to the ocean, gradually emptying this indispensable reserve of fresh water.
18:41Water is key for the Panama Canal because it's also the lake where most of our population drinks water from, in the main cities.
18:50So we have to protect water, save water. So we decided to implement the water-saving basins.
18:54What they do is, all this gravity-fed, with different elevations of water, we're able to recycle 60% of the water per chamber.
19:04And overall, these locks use 7% less water than the existing locks. So it's just a recycling system.
19:12Was becoming one of the great leaders of the Panama Canal a childhood dream?
19:16This is a dream job for any engineer. This project like this doesn't get built every day, and it's very unique.
19:27The locks, the gates, everything, the physical systems, every single day there was something to resolve.
19:33Now when you look back, you're like, wow, we overcome a lot. But you learn. That's the beauty. So it was more good than bad.
19:40This technical prowess is also a financial success for the Canal Authority.
19:47Every cargo ship passing through pays a colossal sum, between $500,000 and $1 million.
19:58In an era where 90% of global trade is seaborne, the Canal has become the economic heart of Panama,
20:05and one of the world's leading trade centers.
20:07But the country is already considering a fourth set of even larger locks,
20:13to accommodate cargo ships over 400 meters long.
20:19The idea was prompted by China's plan to open a canal in Nicaragua,
20:23allowing through cargo ships carrying 25,000 containers,
20:26and in anticipation of the Arctic routes opening up as a result of climate change.
20:37The water is a major concern for mankind, and engineers have come up with some brilliant ways to divert it,
20:45in order to create waterways that considerably reduce travel distances.
20:49In their attempts to master it, some have even managed to redraw the landscape and recover territories from the sea.
20:57The Venetians put some bold strategies into practice when they built a city that should never have existed.
21:14Venice sprung up in a huge lagoon dotted with marshy islands.
21:21The hostile site was specifically chosen by the Venetians to escape the barbarian invasions and protect themselves.
21:31Today it's an architectural treasure, a UNESCO World Heritage Site.
21:35With its countless canals and palaces, Venice is testimony to mankind's genius for mastering water.
21:46When the first inhabitants arrived here, they learned a specific technique to build houses on this unstable ground,
21:55on muddy, on a very muddy ground.
21:57First of all, with the technique of bonification and wooden pole, they created a basis.
22:05And below that surface, we have millions of poles that have been put to make a stable ground.
22:16In St. Mark's Square, there are possibly 200,000, 300,000 poles.
22:21And when you are walking through Venice, possibly you are walking on top of the largest forest, fossil forest in Italy.
22:31It's a very nice example of the way in which Venice mastered the waters for centuries.
22:40Masters maybe, but still subject to the rhythm of the water.
22:43The Aqua Alta conditioning very much life for Venetians.
22:50And when it happens, everyone is obliged to go into the passerelle.
22:57Also for people living in the houses, it's very unsafe to live on the ground floor.
23:05And it's better to stay on the upper floor.
23:08The Aqua Alta is caused by many factors, making it very difficult to predict.
23:14In Venice, tidal phenomena account for only 20 to 30% of the Aqua Alta.
23:23During the highest tides, the water rises a maximum of 50 centimetres.
23:29Sea level is also affected by atmospheric pressure.
23:32High pressure above 1,013 hectopascals forces the sea down, while depressions cause it to rise.
23:42A big depression, then, can thus raise the water by up to 30 centimetres.
23:47It's often accompanied by heavy rains, which make the situation worse.
23:51Finally, a strong, constant wind blowing towards land can cause a significant rise in the water level of up to one metre.
23:58More and more frequently, the Venetian Republic is coming under threat from the Adriatic Sea.
24:16Every autumn, increasingly high waters flood the city.
24:19The worst was probably the Aqua Grande of November the 4th, 1966.
24:39Driven by a storm and a strong southeasterly wind, the water rose to 194 centimetres above the reference level.
24:465,000 Venetians lost their homes, concerned that Venice might be swallowed up entirely spread across the world.
25:05In the 1970s, to save the city, a unique barrage was designed in the form of the Mohs project.
25:11After 15 years of massive construction works, this ingenious system of floating gates attached to the bottom of the lagoon is entering its final phase.
25:26The system is managed from a control center.
25:30Since 2011, whenever floods threaten, computers can close the barriers virtually, simulating an emergency.
25:36On these screens, we see the information that the operator will consult when deciding whether or not to operate the gates.
25:47They arrive directly from each opening and give the status of each sluice.
25:52There is also marine weather data.
25:54So when do you decide to close an entry?
25:59The Italian state has defined the rules to put these mobile gates into operation.
26:04The water must rise to 1.10 metres above the reference level.
26:08When we decide to lift the gates, air is injected.
26:18They pivot around the hinges to a position of 45 degrees, the operational angle.
26:25To lower them, we inject water instead of air, and then they sink, returning to a horizontal position on the bottom.
26:35Why not tilt the gates at 90 degrees?
26:39We don't place them vertically, because at 90 degrees it would be very difficult to get them back in position on the bottom.
26:49From 45 degrees, gates can reposition themselves naturally thanks to the force of gravity.
26:56That's really clever.
26:59It takes 30 minutes to fill the 78 valves with air, and another 30 minutes to bring the gates to operational level.
27:09The movable barrier is designed to hold back up to 3 metres of rising water.
27:14Was global warming taken into account in the Mohs project?
27:18Yes. The Mohs system is one of the first that the Italian state has carried out taking this problem into account.
27:24A hypothetical rise in sea levels of up to 60 centimetres in 100 years has been factored in.
27:35A high price has been paid by the Italians for this bold technology.
27:39An estimated 5.5 billion euros, not counting cases of corruption.
27:48This is the main grievance for the project's many detractors.
27:51They complain that the system does nothing to ease the main threat to the city, with Venice subsiding by several millimetres every year.
28:12Further north in Europe, in the Netherlands, a whole nation has made the control of water its speciality.
28:17Over the centuries, the Dutch have become formidable hydraulic engineers, reclaiming huge tracts of land from the sea.
28:28More than 20% of their country is built on previously submerged land, reclaimed from the sea, known as polders.
28:38Several centuries ago, in order to create polders, the Dutch first surrounded the area they wanted to build on, isolating the marshes to be drained.
28:50Then they planted reeds to absorb the water.
28:55But this technique proved to be insufficient.
28:59They went on to cover the area with canals to drain away the water.
29:02The Dutch then built windmills with a screw to pump the water away, discharging it into a channel upstream towards the rivers or the sea.
29:14The Netherlands used more than 10,000 windmills to drain the land.
29:24In the 20th century, reclamation has intensified, completely redrawing the map of the country.
29:29On January the 1st, 1986, a new province was born, called Flevoland.
29:36The new land was formed by merging two existing polders.
29:41With an area of 25,000 square kilometers, it's the largest polder in the world and the biggest dewatering project ever undertaken.
29:49Since the Middle Ages, the Dutch have reclaimed an area of 220,000 hectares from the sea.
30:00But the conquest has not been without consequences.
30:03One third of the country is below sea level, and 60% of the population lives in flood-prone areas.
30:12In 1953, a devastating storm forever changed the face of the country.
30:19On February the 1st, a very high tide coupled with the depression and roaring 150-kilometer-an-hour winds rose up against the North Sea dikes with phenomenal force.
30:34In the middle of the night, in the south of the country, 89 barriers gave way, allowing 4.5 meters of glacial water into an area of 200,000 hectares.
30:43The result was devastating.
30:4547,000 buildings were destroyed, tens of thousands of animals drowned, and most tragically of all, 1,835 people died.
30:55As a result of this unprecedented disaster, the Netherlands set about the largest civil engineering project ever undertaken.
31:03The Delta Plan.
31:04Over a period of 30 years, the project aimed to build the most powerful ramparts ever imagined.
31:11Dykes and indestructible dams to lock out almost every arm of the sea and river estuary in the south of the territory.
31:17Near Rotterdam stands the keystone of the Delta Plan, the Eastern Schilt Storm Surge Barrier.
31:30Completed after an extremely complex 10-year construction project, this innovative barrier is several kilometers long.
31:39Dozens of 42-meter-wide, 5-meter-thick steel gates allow the strong currents of the North Sea to pass through, or repel them when the elements go wild.
31:48I imagine that building such a dam required many innovations.
31:58Yes, everything had to be invented. No structure had ever been built like it, anywhere in the world.
32:04Anywhere in the world.
32:09The original design of the Delta Plan provided for the construction of a conventional closed dam.
32:15And work began in 1974.
32:20However, environmentalists and fishermen protested because the oyster in mussel beds would not have survived.
32:27It would also have been a disaster for plants and other living organisms.
32:32So they stopped the procedure and the government decided to build an open dam instead.
32:39The engineers had to invent a completely new type of barrier, able to support a flow of two cubic meters of water per second.
32:49Affixed to the seabed are 65 enormous concrete pillars, each weighing 18,000 tons.
32:55Between them are sliding steel gates moved into position from the control room as soon as the water reaches three meters above the reference level.
33:05It takes 75 minutes to complete this North Sea inlet.
33:09With this Delta Plan, the Netherlands has become one of the safest coastal territories in the world, thanks to its innumerable dikes and more recently its mobile water defenses.
33:23Over the centuries, the Dutch have become specialists in mastering water.
33:30The expertise of their 2,500 companies and laboratories working on the issue is recognized worldwide.
33:36In Delft, Frederic Restagneux, an expert in fluid mechanics, visited one of the most important hydraulic research centers in the country to find out about the work being carried out by his Dutch colleagues in their quest to develop increasingly effective coastal protection systems.
33:54It's really big.
34:01It is big, yeah. It's 75 meters long, almost 9 meters width.
34:05In this kind of wave basins, we do research on dikes, ports, storm stress barrier like a project in Venice, the MOSA project. Storm stress barriers have been tested in this facility.
34:16What's special about this basin?
34:18This is the Atlantic basin where we can generate not only waste but also a current.
34:25So we have waves from that side but we can have currents also from that side.
34:30And that is important if you have, for instance, material that is being steered up by the waste and transported by the currents.
34:41All the experiments here deal with an unpredictable element, water.
34:45In order to simulate its behavior and collect accurate data, each pool is equipped with one or more wave generators.
34:58The waves here don't have a very regular form.
35:01No, like in the reality, not each wave is the same.
35:04So when you look to a storm, you have higher waves and you have lower waves.
35:09You have longer waves and you have shorter waves.
35:10Depending where we are in the world, the frequency of the waves might be different.
35:23We know how to program that to the wave generator and that is very essential.
35:28It's a tool that allows scientists to study the resistance of dikes in the long term, as well as in extreme situations.
35:38For analysis purposes, researchers have built a 300 meter long canal.
35:43This is the distance required to reproduce the gradual formation of waves and allow 4.5 meter high waves to be generated.
35:50Giant basins are also essential for large-scale study of how to protect increasingly threatened coastlines.
36:05Has global warming increased demand?
36:07Of course, so it is one of the aspects that we deal with in each project.
36:13We need to construct dikes that we can easily adapt if the sea level rise will be more than what we expect now.
36:22But if your expectations is wrong, and it's not one meter but it's two meter or three meter,
36:28then you still should be able to adapt the structure to a different sea level rise.
36:33Here in Holland, such tests must be particularly important.
36:37Yes, in the Netherlands, it's very important that we have facilities like this to investigate.
36:42If you make an error, the consequences are much larger in the Netherlands than in other countries.
36:50The increased risks led the Dutch government to launch a new delta plan in 2015
36:55to strengthen and heighten many of the country's surge barriers.
36:57A rise in sea level of between 65 and 130 centimeters is predicted by 2100,
37:14and up to 4 meters by 2200, aggravated by subsidence of the soil and significant erosion of the coastline.
37:21In order to limit greenhouse gas emissions, engineers increasingly harness the tremendous power of water.
37:34The impressive nature of hydroelectric dams means that they produce almost 80% of the world's renewable energies,
37:53compared to 12% for wind, 7% for biomass, 1% for geothermals and 3% for solar.
37:58In the 20th century, 70 dams in 14 different countries are the work of brilliant French engineer André Coyne,
38:09the undisputed master of the arch dam.
38:12His creativity has inspired generations of builders.
38:15What characterised André Coyne was his desire to experiment and work things out in the best possible way.
38:25He made a range of innovations.
38:28Spillways, for example.
38:33Whenever floods occur, it is important to protect the foot of the dam from damage by the increased flow.
38:39He invented what became known as the ski jump, which projects the water far enough away to ensure that damage is inconsequential.
38:48He also pioneered the incorporation of measuring equipment into the concrete.
38:54The calculations he came up with paved the way for further development of the arch dam.
38:58He also insisted that it had to be beautiful.
39:13It was André Coyne's philosophy that nature must prevail.
39:17We do not impose on nature, we take a rather immodest step of barring a river, and we need to understand it.
39:24He was of the view that some kind of empathy must exist with the rock, the river, the concrete and the earth.
39:32Putting oneself in nature's shoes is not being arrogant. On the contrary, it is a way of submitting to it completely.
39:43While Coyne became famous for arch vaults, often built in steep areas, there are other types of dams built in rivers such as the Gravity Dam.
39:50All share a common feature. To build them, engineers must interrupt the natural water course.
40:01To build such a structure, it is first necessary to drain the area chosen for construction.
40:06The water course must thus be diverted into the banks through a temporary channel, or in more rugged regions, through huge diversion tunnels.
40:12The excavated rocks are then used to build coffer dams, dikes and temporary barriers that help drain the area.
40:20Once the water course bed is dry, excavation can begin.
40:25The solidity of the support is ensured through intensive studies and high strength concrete is used on any ground deemed unfit for the foundations.
40:33Once the site is finished, the cofferdams are dismantled to put the dam in water and create its vast reservoir.
40:43The quality of the rock is essential in building a dam.
40:48The moment when a dam is first put in water is one that no engineer, not even André Coyne, experiences with serenity.
40:57Of all the edifices built by man, said Coyne, dams are potentially the deadliest.
41:03His words were prophetic.
41:04In 1954, André Coyne completed the Malpassé arch dam in the south of France.
41:13The reservoir allowed the farms around Fréjus to be irrigated.
41:17It was built in the RĂ©ron Valley, a water course that runs dry in summer and floods in winter.
41:25The wait went on for several years until the water filled it completely, 1955, 56, 57.
41:31And there were no checks, there was nobody on the spot.
41:36Since there is no electric plant, the construction was there purely to collect water,
41:41there was no monitoring and warning signs went unheeded.
41:45Noises, water dripping in some places.
41:48On the left bank, the water had infiltrated the rock, which caused cracks and faults.
41:53Then on December 2, 1959, the dam burst.
42:01At around 9pm, a 40 metre high wave rushed into the narrow valley, at a speed of 70 kilometres an hour, sweeping away everything in its path.
42:11Braking on Fréjus 20 minutes later, before flowing into the sea.
42:14The damage was catastrophic, claiming more than 423 victims.
42:23France was in shock. André Coyne took full responsibility for the tragedy.
42:28When everything was checked, there was not a single miscalculation.
42:42In fact, the arch was well designed. It wasn't a design fault, it was a geological fault.
42:49The Malpassé tragedy prompted a rethink with engineers all over the world.
42:54They realised they didn't understand what was happening in the rock.
42:58Something we have learnt is that the rock must be allowed to drain, by drilling into it and tunnelling to ensure there is no build-up of pressure inside the rock.
43:11Much of what we know about drainage and rock mechanics stems from Malpassé.
43:15But that doesn't mean it wasn't a dreadful tragedy.
43:22The biggest civil engineering disaster of the 20th century has significantly improved the safety of dams.
43:28All are now equipped with drainage systems.
43:35With ever-large constructions being erected, security is an essential element and the energy potential is immense.
43:41Water is an asset widely exploited in South America, particularly in Paraguay, which is one of the few countries in the world that is 100% hydroelectric.
44:00Frederick Vrestaño went to this small state sandwiched between Argentina, Bolivia and Brazil.
44:10Although landlocked, the country is crossed by one of the largest rivers in Latin America, the Parana River, which forms a natural border between Brazil and Paraguay.
44:19Driven by several waterfalls, such as Saltos del Monde, it drains an immense volume of water with unparalleled power.
44:34A few kilometres away, this resource has allowed Paraguay and Brazil to jointly build the binational ItaipĂş Dam.
44:40It's the most powerful hydroelectric plant in the world and one of the largest dams on earth.
45:00It's a really amazing place. It's gigantic. How big is it exactly?
45:12The dam measures nearly 7.5 kilometres.
45:19Its total height is 225 metres.
45:23225 metres?
45:25Above sea level, exactly.
45:27How high is the waterfall?
45:31It falls 120 metres. Water hits each turbine, producing 700 megawatts.
45:37So each turbine is roughly the same power as a nuclear reactor?
45:42ItaipĂş Binacional has a capacity of 14,000 megawatts.
45:47So compare that with a nuclear plant producing 1,000 megawatts.
45:52That's the equivalent of 14 nuclear power plants. It's really amazing.
46:00This monster supplies almost 90% of the electricity consumed in Paraguay and 50% of its Brazilian neighbours' electrical power,
46:09thanks to an architecture and location that was thoroughly studied by engineers.
46:13What kind of dam is the ItaipĂş Dam?
46:18It's a gravity dam built on very solid basaltic rock, the same as can be found along the river.
46:25It was built on the Parana River Canyon.
46:33The site of the ItaipĂş Power Station was chosen by engineers because this was where it was possible to extract the most electrical energy from the flow of water into the power plant.
46:48They have achieved the best possible rate of productivity.
46:56So it's a combination of water flow and geology that makes this the optimum location?
47:02Yes.
47:03Completed in 1991, the structure forms a gigantic 1,350 square kilometer reservoir.
47:13But the sacrifices demanded by this incredible dam are commensurate with its height.
47:20To create the lake, the authorities had to displace 10,000 families and drown the rainforest beneath 100 meters of water.
47:27The first dam construction site with an animal rescue plan, the site is now classified as a UNESCO Biosphere Reserve.
47:44The plant and dams stand on exceptionally strong foundations capable of holding back 29 million cubic meters of water.
47:50It's gigantic!
47:58Yes, it is.
48:01And so this is the bottom of the Parana River. Are we really on the riverbed?
48:09That's right. These are the foundations.
48:12It's actually the base, the lowest level of the main dam.
48:20As you can see here, all this rock dates from the time of construction.
48:25Is the toughness of basalt important for the Itaipu Dam?
48:30Absolutely.
48:32So the dam is just standing on rock?
48:36In concrete terms, yes.
48:38But the strength of the dam rests on 81 billion tons of reinforced concrete.
48:46It's an impressive weight.
48:49To save concrete, a not unduly burdened structure which could damage the bottom of the river,
48:56the builders designed a hollow dam supported by buttresses.
48:59The architecture redirects forces to the bottom, and thanks to its wider base,
49:07allows it to better withstand the enormous pressure of water.
49:10The dam thus stabilised, the engineers equipped it with 20 gigantic penstocks,
49:16creating a drop height of nearly 120 meters,
49:20which discharges 700 cubic meters of water per second directly into each turbine.
49:24Electricity is produced at the foot of the structure in the largest hydroelectric plant in the world.
49:34This is the big machine room.
49:40Below all these red covers are all the generators.
49:44It's crazy to think that this uses a simple principle of physics, which is the dynamo, only in absolutely gigantic dimensions.
49:56All physics is here. Electricity, fluid mechanics, electromagnetism, everything.
50:04Pretty much everything. Here we apply practically all the sciences of engineering.
50:08But despite their ability to provide clean energy, even larger dams involve sacrifices with populations displaced,
50:20and hydrological regimes and water ecosystems modified.
50:23Any costs that building this dam might have had on the environment, I can ensure you are outweighed by the benefits,
50:41starting by the huge amount of energy produced, which is clean.
50:44And if we look what you would need to do to create the same amount of energy, our calculation is about 500,000 barrels of oil per day.
50:54Itaipu's production allows us to avoid about 85 million tons of CO2.
51:02Controlling water is, first of all, about using it in the best way possible.
51:09But it's also about really understanding the water cycle, treating it as well as possible, and not spoiling it at any time.
51:18Thank you very much.