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ITAIPU DAM

A dam that created a lake 170 km long and an average seven km wide is also one of the world’s largest generators of renewable, clean energy. Chris Sheedy tells the story of mega dam Itaipu, an engineering wonder that brought two countries together.

In the 1960s, in the mighty Parana river of

Central south america which runs for 4880 km

and is second only in length to the amazon, a

small islet bravely stood amidst the rush of water.

on the border of Brazil and Paraguay, the

island and stretch of river around it, known as

‘itaipu’, was immortalised when work began nearby

on one of the largest dams the world had ever

known. the dam would be given the island’s name.

it was an admirable gesture, but would soon be

forgotten as the enormity of the dam’s construction

was realised. Concept negotiations between

Brazilian and Paraguayan government ministers

had taken several years, with an act finally being

signed in 1966. Design studies did not begin

until 1971 and in 1973 a treaty, an essential legal

instrument allowing hydroelectric exploitation by

both nations, was signed.

“if itaipu is currently the largest generator of

clean, renewable energy on the planet, it is because

it overcame numerous challenges, even before

the project started,” says itaipu’s engineering

superintendent, Jorge Habib Hanna el Khouri.

“the first challenge was overcoming the deadlock

regarding the border dispute between Brazil and

Paraguay. the vision that led to the creation of itaipu

Binacional [formed to oversee the building of the

dam and its ongoing management] was

beyond power generation for both countries –

the integration between nations was also a goal.”

ItaIpu dam

PROJECT THAT CHANGED THE WORLD:

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ItaIpu dam: by the numbers

ReseRvoiRWater volume at the usual maximum level: 29 billion m³

extension: 170 km

Usual maximum level (quota): 220 m

Area in the usual maximum level: 1350 km²

spillWAyMaximum outflow: 62.2 thousand m³/s

Maximum release capability: 162,200 m³/s

length: 483 m

Gates: 14 units

Gate size: 21 m/high and 20 m/wide

DAMHeight: 196 m

Total length: 7919 m

RiveR BAsinArea: 820,000 km²

Average annual rainfall: 1650 mm

Average outflow: 11,663 m³/s

GeneRATinG UniTspower: 700 MW

voltage: 18 kV

Frequency: 50 to 60 Hz

Drop: 118.4 m

Rated outflow: 690 m³/s

Weight: 6600 t

poWeR HoUselength: 968 m

Width: 99 m

Maximum height: 112 m

pensTocksQuantity: 20

length: 142 m

inside diameter: 10.5 m

Rated release: 690 m³/s

TURBinesoutflow: 700 m³ of water/s

excAvATionsvolume of soil excavated: 23.6 million m³

MATeRiAlsvolume of concrete used: 12.7 million m³

Above: The world famous Iguazu Falls are a few kms from the Itaipu Dam, but in a different catchment.

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ITAIPU DAM

“the initial task was to create a sustainable

governance model in the long-run. the itaipu

treaty, approved by the congresses of both

countries, consumed enormous diplomatic efforts

to achieve a fair and balanced document. thus, the

treaty complied with the aim of solving the border

issue and, at the same time, it opened a perspective

of development for Brazil and Paraguay, through

the power generation business.”

Engineering epicin 1975, work began. after the construction of

essential buildings and roads, the first major job was

the seemingly impossible rerouting of one of the

world’s mightiest rivers. around 55 million cubic

metres of earth was removed in order to excavate a

two-kilometre detour – 150 m wide and 90 m deep

– to give engineers a dry river bed to work on. two

cofferdams that had been built to protect the new

river course were destroyed on 20 october, 1978,

with the help of 58 t of dynamite, sending the river

on its new path.

at the same time, between 1975 and 1978, over

9000 houses were built on both river banks in a

process that el Khouri calls “a true engineering

epic”. the resulting city, known as Foz do iguacu,

had a population of around 20,000 and boasted its

own hospital.

speaking of settlement and re-settlement, a recent

academic study conducted within the university

of geneva, on the topic of development-induced

displacement and resettlement, said that even before

work began on itaipu Dam around 10,000 people

living by or near the river had to be moved to

new locations.

By the time the dam was complete, the report

says, around 59,000 people had been displaced.

similar numbers of people had to be re-settled for

Brazil’s sobradinho and itaparica Dams.

The first major job was rerouting one of the world’s mightiest rivers.

Maintenance works underway.

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ITAIPU DAM

types of damsItaipu is actually a combination of four dams. The main dam is a concrete ‘gravity dam’ – meaning the sheer bulk of the wall holds the water back. Three other dams were built to create the 7.9-km mega-dam.

They consist of an earthfill dam and a rockfill dam (both ‘embankment dams’), and a concrete ‘wing dam’, a barrier that extends part of the way into the river to force the water into a fast-moving channel.

There are several types of dams, each used for different purposes or to suit various environmental factors. Here are some examples.

GRAviTy DAMTypically a massive dam made with concrete or stone masonry. A gravity dam is able to hold back large volumes of water thanks simply to its size. Gravity holds the dam to the ground and prevents water pushing it away. An Australian example is WARRAGAMBA DAM in New South Wales.

ARcH DAMAs the name suggests, these dams are curved against the upstream side of the dam, therefore transferring pressure from the water to either side of the dam wall. They are thinner than a gravity dam. Arch dams are suitable in a relatively narrow valley or canyon that offers strong, natural side walls. An Australian example is GoRDon DAM in Tasmania.

eMBAnkMenT DAMMade from compacted earth, embankment dams rely on their weight to hold water back. Appearing much like a bank or a hill, embankment dams are made from soil, sand, clay and/or rock, compacted into a mound. The process creates a semi-pervious waterproof covering and an impervious core, ensuring seepage erosion does not become an issue. An Australian example is DARTMoUTH DAM in Victoria.

BARRAGe DAMOften employed to control tidal waters, a barrage dam usually consists of a series of low gates that control the amount of water passing through, or block seawater from fresh water in lower reaches of rivers. An Australian example is GoolWA BARRAGes in South Australia. (Image copyright MDBA. Image creator is Arthur Mostead.)

Above: The main Itaipu dam is a gravity dam.

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ITAIPU DAM

Jinping-i DamCHINA

305 mConcrete arch dam

Planning for the Jinping-I Dam actually began in the 1960s, but construction occurred much later, lasting from 2005 to 2014. The dam acts as a hydropower station on the Yalong River, and is capable of producing 16 to 18 TW-h annually.

nurek DamTAJIkISTAN

300 mEmbankment dam

Another hydro-electric station, the Nurek Dam was constructed by the Soviet Union from 1961 to 1980. While it is an embankment dam, usually filled with earth or rock, this one has a unique central core of cement.

Xiaowan Dam CHINA

292 mConcrete arch dam

On the Lancang River in Yunnan Province, the Xiaowan Dam is the third largest hydroelectric station in China. It was constructed between 2002 and 2010 at a cost of US$3.9 billion.

XiluoDu DamCHINA

285.5 mConcrete arch dam

Completed in 2013 at a cost of US$6.2 billion, the Xiluodu Dam crosses the Jinsha River and its power station boasts an installed capacity of 13,860 MW from 18 turbine generators.

seven aerial cables pumped concrete at a

prodigious rate. on 14 november, 1978, the builders

poured 720 cubic metres of concrete into the base of

the gravity dam, which was a new south american

record, according to itaipu Binacional. this was the

equivalent of a ten-storey building every hour, or

24 ten-storey buildings in one day. and this project

would use a lot of concrete – 12.7 million cubic

metres, to be precise.

over 20,000 trucks and over 6500 railway cars

were used to haul the raw materials to the site.

every month from 1978 to 1981, up to 5000 people

were hired. at one point, 40,000 staff were clocking

in every day on the site and in support offices.

tragically, by the end of the project, which cost

us$17.4 billion, 149 workers would lose their lives

building the 7.9-km long dam.

When construction ended in october 1982,

the lake, covering 135,000 ha, took just 14 days to

fill, thanks in part to torrential rain in the region

and upstream. in mid 1984, it was time for the

hydroelectric power plant to do its thing when

the first of 20 generating units was switched on.

By 1997, 26% of Brazil’s electricity demand was

supplied by itaipu. in 2000, the dam generated

93.4 billion kWh. today, the dam provides 17% of

energy consumed in Brazil and 75% of energy

consumed in Paraguay.

Today the dam provides 75% of energy consumed in Paraguay.

Above: a tour of the hydroelectric plant.Right: a stoplog being moved.

Above:Switzerland’s Grande Dixence Dam.

granDe DiXence DamSWITzeRLAND

285 mConcrete gravity dam

On the Dixence River in Switzerland’s Valais region, the Grand Dixence Dam is the world’s tallest gravity dam. It was completed in 1964, and its four power stations produce around 2000 GWh annually.

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ITAIPU DAM

energy is provided by 20 generator units, each

34 m apart and comprising scroll casing, turbine,

generator, excitation system and speed governor.

energy is delivered via three substations inside

itaipu (two gas-isolated substations, one operating

at 50 Hz and the other at 60 Hz, and a conventional

50 Hz substation) to external substations on each

country’s side of the dam. it is then transmitted to

consumption centres.

Just as important as the dam’s technical success

is the effect it has had on community education.

itaipu’s Cultivating good Water program was

recognised by the un for the way it engaged

families, communities, municipalities and

businesses around the vitality of a high-quality and

unpolluted water source.

“the work was not complete until itaipu

assumed an expanded role, whose challenge is

to act strategically in territorial development and

environmental care,” el Khouri says. “global and local

recognition is an important indication that itaipu is

overlapping the challenges the responsibility that a

project of this size requires.”

Open spillway at Itaipu Binacional.

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