A dam is a barrier designed and constructed to
contain the flow of water. It is often built in conjunction with a
hydroelectric power station to provide electricity.
Dams are built for purposes such as generating
hydroelectricity, creating recreational areas, minimizing flood risks,
diverting water for irrigation, and providing water for towns and
The type of dam built in any given situation
depends on factors such as the intended purpose, environmental
considerations, available finances and the location.
Different types of dams include masonry dams, embankment dams and arch-gravity dams.
Beavers create their own dams from sticks and mud as protection from predators and also to help provide easy access to food.
Dams are huge engineering projects that require
vast financial resources. For example, the construction of the Itaipu
Dam on the border of Brazil and Paraguay (completed in 1984) cost
around US$20 billion.
Built along the Colorado River between 1931 and 1936, The Hoover Dam reaches 726 feet in height (221 metres).
When the Hoover Dam was completed it was both the world’s largest concrete structure and largest hydroelectric power station.
The Hoover Dam is made of enough concrete to make a
two lane highway from New York to San Francisco, that’s around 4000
miles (2500 kilometres).
As of 2010, the tallest dam in the world is Nurek
Dam in Tajikistan. Completed in 1980, it reaches 300 metres (984 feet)
Many dam failures have occurred in the past, these disasters can cause significant damage and threaten lives.
In 1889 a failure of the South Fork Dam near Johnstown, Pennsylvania, USA, killed over 2200 people.
In 1975, the Banqiao Dam in China was among many
dams that were destroyed after the extreme rains of Typhoon Nina. It is
estimated that between 90000 and 230000 lives were lost as a result of
the Banqiao Dam breaking.
The word skyscraper originally referred to a type of sail on a sailing ship.
A skyscraper is held together by a steel skeleton
of vertical columns, horizontal girder beams and often diagonal beams
for extra support. This structure distributes the immense weight in a
way that ensures the integrity and safety of the building.
Restoration work in 1990 and 2001 shifted the Leaning Tower of Pisa back to an angle of 4 degrees after it was previously leaning at an angle of 5.5 degrees.
The roofs of the Sydney Opera House are covered in a total of 1056006 tiles.
in Rome, Italy, is an elliptical amphitheatre that was completed in 80
AD. It held around 50000 spectators and was used for a variety of
events including gladiator contests, animal hunts and mythology based
Around 20000 workers helped build the Taj Mahal, a famous mausoleum and landmark in Agra, India, that attracts millions of visitors every year.
The world’s largest office building by floor size
is the Pentagon in Virginia, USA, with over half of its
6500000 square foot (604000 square metre) floor area used as offices.
The Empire State Building in New York was the
first building to have over 100 floors and was the tallest building in
the world from 1931 until 1972.
The Chrysler Building in New York was built at a
time when there was a strong desire to build the world’s tallest
skyscraper, before being overtaken by the Empire State Building, the
Chrysler Building was the world’s tallest for around 11 months. During
the construction, floors were being completed at a staggering four per
week. Despite the rush, no workers died during its construction.
The Petronas Towers in Kuala Lumpur, Malaysia, are the world’s tallest twin buildings, standing at a height of 452 metres (1483 feet).
The Burj Khalifa
in Dubai, UAE, is the tallest building in the world. It reaches an
amazing 828 metres (2717 feet) in height. Check out our top ten list of
the tallest buildings in the world.
Tall buildings need fast
elevators, recent developments have led to elevators that can travel up
to, and sometimes over, 1000 metres a minute (3280 feet a minute).