National Geographic: Big,Bigger,Biggest:Dam S02E08 - VoiceTube: Learn English through videos!

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from the waters in the Yangtze River in China
rises the biggest concrete structure a plan
the Three Gorges Dam is over two kilometers long
and 60 stories tool
it has taken forty thousand workers over 70 years to build
when it fully comes online this one down
will produce over 20,000 megawatts how
twice as much as cool the nuclear power stations in Britain put together
it is the pinnacle damn engineering
home the Three Gorges Dam
owes its success to 5 landmark times
in the heart it leaves lies a major technological innovation
allowed engineers to build and big data
one by one traveling up the scale will reveal the incredible stories behind
the structure
on
and the inventions that allowed them to produce
evermore power
6 ingeniously forward from being
to bigger into the world
things
I'm
here I'm
them
I'm
China is one fastest-growing economies on
to fuel the need to mix ever accelerating industry nation needs more
much in this would be provided by an enormous
down spanning the mighty Yangtze River in central China
called the Three Gorges
our cameras have been granted privileged
access to capture this amazing feat of engineering
in its full glory
the
before they could start building 3 largest the Chinese first had to divert
the Yangtze
River which is almost two kilometers wide and move
over a million people from the area about to be flood
Three Gorges Dam is the biggest hydro-electric project in the world
this damn news 28 million cubic meters a cock maybe one way to look who's to say
saw solid hyper concrete a meter diameter
right around the world lot a concrete
the chinese authorities think it's worth the effort as the Three Gorges Dam will
provide clean
and cheap electric power to millions
to understand how the Three Gorges Dam can produce so much
we need to travel back in time
to nineteenth-century Britain
and a modest stream in Northumberland the power behind the world's
first hydroelectric dam
in the eighteen hundreds while Britain is at the heart of the Industrial
Revolution
this house is the last word in modern lived
it belongs to Lord Armstrong an entrepreneur
and obsessive invent he has fitted his house with state-of-the-art technology
including central heating and mechanical devices that drive elevators
laundry machines and roasting space
but there is one place in the house where modern technology
is sadly lacking as historian and Tony Burke
explains this was Armstrong's
real pride and joy the picture gallery for wonderful Victorian paintings
bit gloomy even in daylight what he really wanted to do
was to bring his guests here in the evening by the flicker candle light
nothing really worked
what Armstrong needs
our electric lights and away to power them
how do you generate electricity that something was known for
fifty years was Michael Faraday a given the secret you move
a magnet in relation to call on work bundle set appear
so how it might work now
here we are here we've got to magnets
on the end this disc and right here is a call love one now
if I make this spin mission to that we should
make electricity on
yet getting reading on a meter we are definitely
taking elect every time the magnet some
this moved past oil generated tiny
electric handsome copper wire make a lot of electricity
you need much bigger Kate and this is what Armstrong board
Thomson vortex turbine agran peace equipment
the thompson turbine needs a huge volume of fast-flowing water to drive the road
Lord Armstrong has available
is a tiny stream trickling through his estate
what he needed was this a lotta water
hud's again this on a small stream a
built a dam mom
Armstrong builds and Perth wall nearly ten meters high
which turns history into a deeply
this massive water pushing down increases the pressure at the moment
Armstrong channels this high pressure water down through a pipe
to the bottom now
he injected into a Thomson to her by with Tara
spins the world
this in turn road takes a shot lead to a generator
the produces four thousand wats electricity
for Armstrong this is only the first step to enlightenment
now he needs to get the electricity from the turbine house at the bottom it is
Dom
all the way to his picture gallery over a kilometer away
Armstrong connect two strands of the copper wire to the generator
to carry the electricity up to as much all in all
uses five tons of copper to power
a single like gold
but he has created a world-first house
let's by the power above water ok
on the other side of the planet in central China the Three Gorges Dam
takes Lord Armstrong's concept to the extreme British engineer Robin Charlwood
has been working on the time since 2003
and is still impressed by its scale
wherein
wanna 3 very large powerhouse Three Gorges Project
in this seven hundred meter long from here
you can see 40
large turbine generators then
me on this one kilometer away second
house then be on that one yet another powerhouse
to be underground at the Rock the Bogside their each one of these
generators cost about $50 million dollars
good idea at this scale this project damn damn damn
have one generator Three Gorges has 32
together they produced by million times more power than
them
to drive them the chinese have harnessed the power
the mighty Yangtze River in the reservoir behind the dam
the river now rises up to 60 stories about
river
water is channeled down gigantic concrete choose to walk the generators
here the torrent water hits the turbines and makes
spent
this motion is in turn transferred to the rotary general
this is fitted with a massive magnets which moved past copper coils in the
casing
to generate electricity
just wanna these machines makes as much
electricity as a small nuclear power plant
132 generators together
produced enough power for $60 million Chinese
this project is setting a new benchmark in the international hydro-electric
industry
it's almost twice the size of the next largest project
it out Brazil cause is only the first a whole series that make it at
are under construction here in China
back in 1878 dead and I'm showed that even the smallest
dream can be harnessed to produce electricity
but to generate power on a larger scale engineers had to wrestle with bigger
returns
to build a dam that could produce a 128 make
once French engineers had to persuade the raging
Dordogne river to run courts
France in 1940
the outbreak of the First World War plunged the country into a deep
energy crisis with that cold feels occupied by the germans
the French are forced to import coal from abroad
to feed their power plants and keep the country
going so after the war they decide to boost the nation's power supply
with electricity from a hydro-electric dam but building a concrete dam in the
fast-flowing Dordogne river
presents quite a challenge and this is all a mighty river Dordogne
here on the beach now you call
just Paul concrete in the Middle River they wanted their damn
here but not to get one damn they had to build three
for civil a temperate damn goes in here
what's called a copper damn that stops the river flowing
be cut to stop it is gonna go over the top unless you do something different
bill
a diversion channel right round at and then
to stop it backing back up again you put in a second cofferdam
he annual spacing between which you can drain
and its there you can build your main damn
at the door died
engineers blasts two tunnels through the rock to carry the diverted river
they drop steel cages containing
rocks into the river to make that temporary coffered up
then they strengthen it with concrete
now is the river behind the dam begins to rise
it drains through the tunnel
to stop this water from backing up the engine is built a second cofferdam
once the water drains from the river bed between the dams
it leaves a perfect Dreisbach to build remains
was completely engineers discovered when the into the central part
that actually the riverbed was solid will good bills
straighten top
layer by layer giant concrete structure
rises 30 stories up from the river
the engineers then close the diversion tunnels
and allow the reservoir to fill up and submerge the coffer dams
their job done
finally they can open the gates to the turbines
and stop producing Tricity
when the Marais aged I'm is finished
it produces a 128 megawatts enough to help power train line to only all
and supply the city of Paris 400 kilometers away
with electricity
the Yangtze River is over 6,000 kilometers long
and in places several kilometers wide
the biggest River in China it presents enormous logistical challenges to the
dam engineers
as the Yangtze
rises behind the Three Gorges Dam it will flood over a hundred and fifty
thousand acres of land along its banks
so the chinese have to relocate over a million people from the land behind the
time
thousands of new houses have to be built for the displaced citizens to live it
then the engineers can begin damn River
wrist and here among some in the rocks and these
precast concrete blocks that were used to tree
the coffer dams to control a river during the construction
the Three Gorges Project controlling the river
to allow the construction of this huge project was clearly a major undertaking
and with the Yangtze rivers 1 largest rivers in the world
very fast very deep so building is confidant's and
to allow safe construction was a major operation the Chinese claim that this
was the largest most difficult diversion
ever undertaken for hydro-electric project I'm
you look at the scale of it they were absolutely right this was huge
you
the engine is begin work on a series of stone cofferdam
to block off part of the axe was leaving a channel open for the rest in the river
to flow through
they build the first two sections of the main down on the drive reverb
then they dump tons of earth into the river
and on top of it build another cofferdam this time
from concrete
with the river held in check behind its they can finally bill
the last section at the bath
then they must remove the cofferdam
so that water can flow through the turbines and the main to
having built such substantial cover them structures it's a major challenge how to
remove these things
so in the in the earliest stages where they were built to
very large rocks like this then that could be handled with
big X greater equipment relatively conventional
but in the final stage where they had a solid concrete wall to remove
this required some serious innovation up
unlike the cofferdam in my rage the Chinese version is Jim told to simply
leave it in place
so the Chinese engineers build it leaving holes for explosive charges
on the 6th June 2006
they fill them with 290 tons dynamite and hold their breath
up
what has taken months to build takes only seconds to destroy
as the cofferdam crumbles and unleashes the water stored behind
you
it's the final test for the Three Gorges Dam
and it holds
back in 1935 them are aged I'm proved that engineers could divert rivers to
build powerful
downs
but to break through the 1000 megawatt American engineers building the Hoover
Dam
had to take that building material to the limit
in the 1930s USA decide to tackle one of their big
economic problems the cities in the western United States can't grow
because they lack both water and
so to break the deadlock engineers begin work on the world's biggest dan
the from people who worked on
real adventurous these guys
high sky I would say on a plaque hung from a row
of the top of the cliff and I would go along with hydraulic hammers
basically smashing out cliff place so that when you pour the concrete
up to it would fit together well
they poured more concrete on this damn
then on any other construction projects before
but managing so much concrete can be a big headache for a damage
near when you doing really big concrete poles
is a very particular problem that problem is hate the first thing you have
to understand is that concrete
is made up to three basic ingredients first ball you have this stuff
which is cement now that's the active ingredient that's what reaction changes
you have water which reacts with the cement and have this stuff down here
which is aggregate which is basically
style this case at hand which gives the whole
mixes strange now when we put this cement in here
what we're gonna have is a chemical reaction hydration reaction in fact and
its except for Nick
which means that the temperature this lot should rise Solis
and the test and see if we write we can see it rising there
and it's already gone up to 15 degrees C
and if we wait around little while longer I'll go up some more what we've
seen a
is that we do get temperature rises not much but actually when you're in the
middle of a great big concrete pole
hate has got nowhere to go and so the inside
lump of concrete gets hotter and hotter and hotter and expands
when expands it cracked the concrete is on the outside a bit
and if you're doing a big concrete porn and dad cracks or a bad thing
up if the concrete at the Hoover Dam is poured in one go
the concrete on the outside world cool and harden first
while in the core of the dow the concrete stays hot
and tries to expand this could stress the concrete
and make crime
all so the engineers cast the concrete for the Hoover Dam
in small individual blocks as the concrete in each block
schools it shrinks but it doesn't crap
the contraction leave small gaps between the blocks which
engineers must filled with cement up
but this clever design doesn't solve all the problems
when who the time is enormous
mean there's six million tonnes concrete who the debt
and if we were able to concentrate all over the haiti is generated by that
curing concrete
into a single oven we could cook half a million loans have bred
every day three years this structure
if that was left on its own I think it's gonna take a hundred and twenty-five
years
for it to finish shrinking cooling down basically that's not nearly quick enough
a guy in charge if a local Frank Crowe they callin hurry up kroger is a man in
a Colorado
River to call my dad on
grow embeds over 950 kilometers
steel water pipes into the concrete the damage
well he builds a huge water chilling
factory
here he Kuils River watered down to four degrees
and then shoot it through the pipes into the hard concrete
on
I'm this shortens the cooling time from a hundred and twenty-five years
to only 22 months
now this works a tree all have to do
is finish the dan cement grout up the pipes
and they're out there fantastic effort actually took five thousand men only
twenty-one months to build the structure
not only that they finish two years ahead of time
and they finish had a budget
the Hoover Dam stores $35 billion cubic meters of water
and that the time generate more power than any other dam in the world
with this magnificent damn behind them the cities in the American West
can finally begin to thrive
ok the Three Gorges Dam
takes concrete construction to new heights look at it you can just picture
that fitness is a concrete base in the damn
the hydrant 180 meters minutes
two kilometers long so it's a colossal amount cock
Three Gorges uses
ten times more concrete the Hoover Dam so the engineers have to pull out all
the stops to keep their damn cool
made rescue use everything in the book be
cool D I its materials the sands
before they put into the mix they added ice they did everything they could to
get the temperature down as low as they could
for it starts to warm up for myself and here
because the issue some other summer weather being
specially hardened July holders they actually went so far as to
user fog spray system to blow affectively a
fog blankets over-the-top damn with the objective
blocking this on a radiation from hi down into the concrete and heading to
the
it was being generated on the inside back in 1936
that move a damp proof that engineers could build impossibly big concrete dams
as long as they can cool but as dams grew they held back
ever more water and with it tremendous destructive power
to build the grand coup leader American engineers
to protect from a catastrophic effects about flow
johnstown pennsylvania
30 have made 1889
as the town gets it by the heaviest rainfall its history
the tranquility the dam reservoir is about to be shot
on
it drains for 24 hours and the water
reaches the top done
soon it has nowhere to go but over the top
the dam fails and 20 million tons of water
empties in 45
lemme
a water water 80 meters high crashes down the valley and it's John's
utter destruction and shoes the new over 2,200 lives are lost in the flood
I'll
it is the worst disaster the US as ever seen
why do dams burst when they overflow
engineer Ed McCann explains
now a particular problem is when water flows
over the top and weakens all with the grass the ground in front here very
vulnerable
to single time scale and we're gonna have a go modeling to see if we can see
what happens with toes curl
this is our flood coming along
in our river and fills up behind the dam right up at the top here now
and the wall soon start pushing over the top in coming down
and it will fall down this place and scour Wayland MA
in you can see the damn starting to move already as the ground in front of his
lost
the damn loses its foundation begins to rotate over
they won't be too long before it goes all together and back
which is a reasonably satisfactory dam failure
when it goes we get a tremendous wall
water come down the valley and if you happen to be down there you're probably
dead where you can see that time Skyrim this old dam is a huge potential problem
it's something that absolutely has to be fixed
ok
in 1933 American engineers start work on the ground
coup leader across the Columbia River in the northwest
America a damn that dwarfs even the Hoover Dam
it needs three times more concrete
and spans three times the distance as the engineers complete the grand cooley
they have to make sure that what happened in Johnstown
won't happen here
ok
water rushing over the damn could quickly erode the riverbed
and cause disaster
so the engineers form the box move the damn into a concrete
run
ok
this sense the water shooting down the spillway
into a tumbling cortex which dissipates an edge
as the water cascades of the ramp it loses much of its destructive power
with the ramp in place engineers can safely run the largest hydro-electric
dam in the US
a title that the grand cooley dam retains to this day
just ok
the builders have the Three Gorges Dam
face a similar problem
they too must make sure that their dad is not damaged by flood water rushing
through
basically the damn hold back
large volume with the water during the flood period here
can hold back about 22 billion cubic meters of water
and then its release in a controlled way through this system
forty-six spillway gates and these shoes you can see below me here
the design them a spillway like this
has the deal with the force of the water as
the drops over a hundred meters in this case here
then achieve shoes velocity at the bottom with the damn
to deflect the force of the water crashing down
the Chinese use technology similar to the ground
coolly one
as the water levels rise engineers open a series in
gates to drain the flood water from the reservoir but if the water fell straight
down
could undermine the foundations so the engine is fit the spillway
with concrete shoes
unlike the grand cooley RAM
which is underwater the Three Gorges shoots
pearl the water into the air
once airborne the water breaks up into small droplets
and loses much of its destructive energy
it lands over a hundred meters downstream
where it can't do any damage
so now when they open a spillway gates the Chinese
have nothing to worry about
back in nineteen forty to the grand cooley showed how dams could deal with
the abrasive power flood
but to build a dam across the mighty Genesee River
Russia engineers had to find a way to stop the water
while keeping the ship's movie
in the 1960s the Soviet Union wanted to upscale its industrial power
so they plan a series of gigantic dams
I'm
one of the first the Crocs not ask Dan will stretch a whole Colomb into
across the river Yannis E and generate 6,000 megawatts of power
but this river is also the main shipping
to siberia and would get blocked by to
to keep the ships moving
engineers hatch an ingenious plan they will build a steel
trough big enough to carry shit
then they will push trough and ship up to the top of the time
here they will spend the whole contraption round and lower it back down
to the river
on the upside
to move the seven thousand load they will use hydraulic pumps
engineer
Ed McCann employs a hot water bottle to demonstrate the principle behind
hydraulic power
right connected to my hot water bowl is a
is a pipe which goes into this garden hose
disconnected up to this wat care let's see what happens on lifted up by about
about that meter some left it up to me to
and the pressure in this system has gone up
but it's not gonna enough to lift this year so there's no movement hot wall
but we still squashed flat on the stand back a satellite blocks on the head
some lifting up it's about three meters now
you can see the concrete blocks moving very quickly now
take it
right to talk shit about 4 meters ago
but you can see there is the amazing
power force you can get out water under pressure
that will be used to lift big heavy stuff
the russian engineers use liquid under pressure to lift
shins
in the walls of the chamber a powerful
pumps which squeeze hydraulic fluid under immense pressure into a set of
motors mounted below
up these drive huge deal
clogs the propel the trough along guide
the motors generates so much traction that they left the chamber from river to
reservoir
in only 19 minutes
when the ship left is open the citizens have crews now
ask turn out in droves
this mechanical marvel is the crowning glory
the biggest diamond work
car China's Three Gorges Dam the engineers
also face a major traffic problems their damn said some one of the busiest rivers
in Asia
the Yangtze is a really important waterway
or navigation traffic in china the
alway from Shanghai the coast the chain
or eat it wrong it's been carrying about 18 million
pounds and freight per year
getting about a hundred and seventy ships
day over a damn that's more than a hundred meters high
is a tool order for the engineers befitting the biggest down on earth
the Chinese solve it by building the biggest ship block on
ships enter the lock at the bottom of the pan
gates close water floods in
and lifts the ship's of the next
ships must go through 5t is a blocks to get to the top
which can take up to four hours
this is fine for cargo ships but for the many passenger boats operating on the
Yangtze
it's just too slow to provide a more efficient transit opportunity for
passenger traffic they've built this shiftless system here
which allow boats to go through in about 36 minutes
unlike the ship left it cause may ask
the one at the Three Gorges will lift ship straight up
like an elevator
and the secretive its success life hit
in its concrete wall
ok
the engineers will fit a series of massive counterweights that will do most
lifting
16 1,000 tonne concrete blocks will be connected by
cables to the steel trough that will carry the ship
and the water and floats
as the counterweights drawn they will placed the trough
upwards and left the ship to the top
home
this ship left here is 130 meters
hi and can handle vessels up to three thousand tonnes
you make it largest in the world twice the size
the one across
10 certainly when you look at the structure now it's
got a ways to go terms and construction won't be finished till 2050
but its it's clearly huge some another very impressive achievement on the way
here
after a hundred and thirty years
innovation dams have produced ever more power
today there is hardly a former energy that is as clean as hydroelectric power
but as dams grow bigger so does their impact on the environment
in their design the Three Gorges Dam Chinese engineers have to make sure that
their structure doesn't completely blow
nature's way of feeding line
the Three Gorges Dam produces more power than
any other but that's not the main reason with bill
the Yangtze River is notorious for its really severe flooding
over the last two thousand years as being
about one major flood every 10 years
in 1931 there was a really bad one killed
about 235,000 people destroyed almost two million homes
and so that this is the main reason why the built three gorges dam is to control
this
terrible flooding problem the dam blocks the path
the destructive flood water
the water is stored in its reservoir
and is then released in a controlled way
the managing floodwater
can also have serious environmental side effects
as recent history show
in nineteen seventy Egyptian engineers build the as one Hyde
damn across the River Nile to control flooding
but soon farmers downstream
notice that their harvests are beginning to fail
this soil becomes so barren the farmers need millions of tons of fertilizer
every year to nourish their crops their land has suffered
because it has been deprived of floodwater which carries with it
the vital building blocks life
chemist doctor Andrew should look demonstrates
so we have here are clean rainwater which has been falling
we adding to its in good quality topsoil
we then some animal extra months
we have some snail shells
essentially made of calcium carbonate then we have some
drive leaves clock widget Asian here
and of course fish
as the
store proceeds as the water starts to flow rapidly
all these ingredients get mash top in the
hugely violent storm waters which occur
so here we have it
a veritable cocktail mother nature's
most important plant nutrients nitrogen
force for us counts %um magnesium
and potassium
but if floodwaters stops flowing these nutritious particles of silt will begin
to settle
this is a big problem especially in the biggest damn
1
the flow of pressures yangtze silt is blocked by the dow
and trapped in the slow-moving rest
it rapidly sinks to the bottom
word built up
sorting problem the Yanks is a huge problem
total amount coming down it's about 500 million
tons per year which equates to about
one kilometer cue absent after Phil
big sports stadiums hundreds of times it's a huge boobs
if this silt remains trapped behind the day it would mean the farmers fishermen
and wildlife
would be deprived nutrients in the water the hundreds of miles downstream
home
and the tons have settled silt sentiment could build up in the reservoir and
threatened the damage cell
base sediment falling into the reservoir here with reduce the the capacity the
reservoir capacity in but eventually perhaps interfere with the ability to
run the turbine suppliers
came up
cleverly the Chinese engineers exploit the power
Lord flush the sediment out to the reservoir
and send it downstream
they installed sluice gates deep inside the bat
each gateways as much as a bus and needs a powerful hydraulic piston to lift it
up
when the operators open the games
floodwater rushes over the trap sediment and sweep through the dam
gold
this way the chinese authorities hope that it will be at least another 100
years before the buildup of sentiment
affect power production the time
good even the clever purging system cannot carry
all the sentiment across the damn scientific estimates on how much
sentiment remains behind
vary from as little as 30 percent to as much as 60 percent
the chinese authorities believe that this is a price worth paying
they are convinced that the benefits and the damn
such as clean energy flood control far outweigh
significant drawbacks
as the Three Gorges Project draws to completion
its scale is breathtaking
even with some with its turbines still to be switched on
it produces more power than any other time in the world
standing on the shoulders of historic engineering Giants
the Three Gorges really is ultimate
hydro-electric dam until someone builds
an even bigger