Whether its builder is a beaver or a person, a dam is always used for the same purpose: to manage, direct and prevent water flow. Within that definition, there are many different types of dams, from mammoth hydroelectric generators—which produce 20 percent of the worlds' electricity energy and 88 percent of all renewable electricity—to the small sand dams of Kenya that are designed to store water for the dry season. There an estimated 845,000 dams in the world.
1- 1- Three
Gorges Dam
China's Three Gorges Dam is not only the
world's largest hydroelectric dam, it's also the world's single largest source
of electricity. The construction of the dam has been convoluted: Preliminary
plans began as far back at 1932 but construction but didn't start until late
1994; the dam isn't scheduled to be completely finished until 2011. The
structure's estimated life is as short as 70 years; that was deemed long enough
to justify the displacement of 1.24 million people.
2- Itaipu
Dam
Itaipu Dam, a partnership between Brazil and
Paraguay, generated over 90,000 gigawatt hours of power in 2000—then a world
record for hydroelectric generation. With a height of more than 196 meters, the
dam stands as tall as a 65-story building. Its construction used enough steel
to build 380 Eiffel Towers, along with 12.3 million cubic meters of concrete.
3- Guri
Dam
The Guri Dam in Venezuela not only boasts
sky-high walls and powerful generators, it also has artistic flair. Artist
Carlos Cruz Diez decorated one of the plant's machine rooms in mind-bending
pattern of colorful vertical bars, while Alejandro Otero built an enormous
rotating kinetic sculpture nearby. The dam produces the energy equivalent of
approximately 300,000 barrels of oil per day.
4- Grand
Coulee Dam
Washington state's Grand Coulee Dam is the
largest in the United States. Nearly a mile long and 503 meters wide, its base
area is large enough to hold all the pyramids of Giza. At 115 meters high, the
dam is more than twice the height of Niagara Falls. The dam also has a
memorable role in folk music history—a governmental energy organization
commissioned Woody Guthrie to write songs about the dam in the early 1940s,
including "Roll On, Columbia, Roll On" and "Grand Coulee
Dam."
5- Sayano-Shushenskaya
Dam
Russia's Sayano-Shushenskaya Dam may not hold
any records for its electricity generation, but other dams are no match for its
sheer strength—the structure's stated ability to withstand 8.0-magnitude
earthquakes has earned it a spot in the Guinness Book of World Records. Still,
not even the world's strongest dam is immune to problems—a 2009
accident in which a turbine exploded resulted in
the deaths of 75 people and 40 tons of oil spilled into the river.
6- Krasnoyarsk
Dam
Although the Krasnoyarsk dam has operated
without the notoriety of its Russian neighbor, this concrete gravity dam has
troubles of its own. The plant and its reservoir have apparently wrought
changes on the local climate, causing the area to experience warmer and more
humid weather conditions than the norm, and reducing ice cover in the area,
which is in Siberia. Russia shows off the engineering feat on its 10-ruble
bill.
7- Robert-Bourassa
Dam
Situated over Canada's La Grande River, the
Robert-Bourassa dam reaches 140 meters below the surface, making it the world's
largest underground plant. The dam's centerpiece is a unique "giant's
staircase"—each step is the size of two football fields—that sweeps water
downward.
8- Sand
Dams
Since 1995, Kenya has constructed more than 500
sand dams, which are usually about 50 meters long and 2 to 4 meters high.
Unlike larger dams, which usually are used for hydroelectric power, these
smaller structures are designed to store water during the wet season so dry
communities have a water reservoir when the rain stops. These dams, which store
water buried in silt, do a better job than surface water dams of keeping water
from evaporating and maintaining water quality.
9- Redridge
Steel Dam
Located in Houghton County, Mich., this flat
slab buttress dam is one of only three steel dams in the United States. Built
in 1894, the dam's spillway broke in 1941 and was partially repaired in 2001.
10- Timber
Dams
To limit carbon dioxide emissions from steel
and concrete dam construction, northern Japan's Akita Prefecture started a
project to build small-scale dams out of the country's abundant supply of
cedar. The dams serve mainly to minimize the effects of landslides and mud
flows in the mountains.
11- Inguri
Dam
At 892 feet in height, the Inguri Dam is the
world's tallest concrete arch dam. Completed in 1978, it was repaired in 1999
at a cost of 116 million euros.
12- New
Cornelia Mine Tailings Dam
In terms of sheer volume, the 7.4 billion cubic
foot New Cornelia MineTailings Dam is the country's largest dam structure. But
this dam isn't used for water—it's used for mining. Mine tailings (loose
collections of crushed rock left over from the mining process) were dumped here
before the mine was shut down in 1983.
13- Syncrude
Tailings Dam
The Syncrude Tailings Dam holds the highest volume of material of any dam in
the world: 540,000,000 cubic meters. This dam holds tailings from oil sands
extraction; 500,000 tons of tailings are produced each day.
14- Verzasca
Dam
The Verzasca Dam, completed in 1965, is
renowned for its beauty and its slender concrete arch. The design used less
concrete than comparable dams, resulting in lower construction costs. When its
reservoir was filled, small earthquakes were triggered.
15- Santee
Cooper Dam System
Built to create jobs in the region during the
Great Depression, the Santee Cooper Dam system boasts a reservoir area of
186,000 acres. The dam system, 42 miles in total, survived the third worst
earthquake in U.S. history and was subsequently redesigned and stabilized for
future quakes. The Pinopolis Dam, which is part of the Santee Cooper system,
has the highest single-lift lock in the world for raising and lowering boats
between different levels of water.
16- Roosevelt
Dam
Italian stonemasons crafted this dam,
hand-cutting all the stones for the project. In recent years, the dam's height
was raised 23 meters to increase water storage space by 20 percent, and it was
completely resurfaced in concrete, changing its appearance.
17- Chalk
Hills Dam
The power house connected to this dam resembles
a cathedral, complete with stained-glass windows celebrating the engineers and
bankers involved in the original construction, and small multi-colored terrazzo
tile. The structure was completed in 1927.
18- World's
Largest Beaver Dam
Google Earth found the largest beaver dam in
Alberta, Canada at 850 meters long–the closest size relative exists in Montana
at 652 meters. Viewers think two beaver families constructed this massive piece
of architecture, which contains two separate beaver lodges inside. The entire
dam is surrounded by wetlands, common of more sizable beaver creations.
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