140 lines
8.7 KiB
Plaintext
140 lines
8.7 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[ ]6-8 [ ]Class Notes [Essay on the Effects of ]
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[ ]9-10 [ ]Cliff Notes [Damn Building ]
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[x]11-12 [x]Essay/Report [ ]
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[ ]College [ ]Misc [ ]
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Dizzed: 09/94 # of Words:1236 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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Grade 10 Geography
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Units 12, 13, 14
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Essay - Effects of Dam Building
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Many people have already dammed a small stream using sticks and mud by
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the time they become adults. Humans have used dams since early
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civilization, because four-thousand years ago they became aware that floods
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and droughts affected their well-being and so they began to build dams to
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protect themselves from these effects.1 The basic principles of dams still
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apply today as they did before; a dam must prevent water from being passed.
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Since then, people have been continuing to build and perfect these
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structures, not knowing the full intensity of their side effects. The
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hindering effects of dams on humans and their environment heavily outweigh
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the beneficial ones. The paragraphs below will prove that the construction
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and presence of dams always has and will continue to leave devastating
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effects on the environment around them.
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Firstly, to understand the thesis people must know what dams are. A dam
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is a barrier built across a water course to hold back or control water
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flow. Dams are classified as either storage, diversion or detention. As you
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could probably notice from it's name, storage dams are created to collect
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or hold water for periods of time when there is a surplus supply. The water
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is then used when there is a lack of supply. For example many small dams
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impound water in the spring, for use in the summer dry months. Storage dams
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also supply a water supply, or an improved habitat for fish and wildlife;
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they may store water for hydroelectricity as well.2
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A diversion dam is a generation of a commonly constructed dam which is
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built to provide sufficient water pressure for pushing water into ditches,
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canals or other systems. These dams, which are normally shorter than
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storage dams are used for irrigation developments and for diversion the of
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water from a stream to a reservoir. Diversion dams are mainly built to
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lessen the effects of floods and to trap sediment.3
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Overflow dams are designed to carry water which flow over thier crests,
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because of this they must be made of materials which do not erode. Non-
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overflow dams are built not to be overtopped, and they may include earth or
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rock in their body. Often, two types of these dams are combined to form a
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composite structure consisting of for example an overflow concrete gravity
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dam, the water that overflows into dikes of earthfill construction.4
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A dam's primary function is to trap water for irrigation. Dams help to
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decrease the severity of droughts, increase agricultural production, and
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create new lands for agricultural use. Farmland, however, has it's price;
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river bottomlands flooded, defacing the fertility of the soil. This
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agricultural land may also result in a loss of natural artifacts. Recently
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in Tasmania where has been pressure from the government to abandon the
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Franklin project which would consume up to 530 sq miles of land listed on
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the UN World Heritage register. In the land losses whole communties must
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leave everything and start again elsewhere.5
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The James's Bay Hydroelectric project, hailed to be one of the most
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ambitious North American undertaking of dams was another example of the
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lands that may be lost. The 12.7 billion scheme was to generate 3 160
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megawatts of electricity a day, this power output would be enough to serve
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a city of 700 000! One of the largest problems with this dam, is that it
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would be built on a region that meant a lot to 10 500 Cree and 7 000 Inuit.
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Lands that their ancestors have hunted and lived on for more than 5 000
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years will be flooded along with 90% of their trapping lines.6 If this
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happened these people must resettle, find a new way of life and face the
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destruction of a piece of their heritage if this project is approved.
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When a dam is being constructed, the river where it is supposed to be
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built on must be drained. This kills much of the life and disrupts the
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ecosystem and peaceful being of all the aquatic and terrestrial animals
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around it. At fisheries there is a large impact on the fish. The famous
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Columbia River saw it's stock of salmon drop considerably after the dams
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were built, although there were fish ladders built. The salmon were unable
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to swim upstream when it was time for breeding as they usually did.7
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But perhaps it is the plans for the Amazon Basin in Brazil that shows us
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how large the side-effects can be. In the city Surinam, in northern Brazil,
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Lake Brokopondo was created in 1864 swamping about 580 square miles of
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virgin rainforest. Foul smelling gas called hydrogen sulfide was produced
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as the trees decomposed. The turbine casings were attacked by the acidic
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water and the decay of water allowed a chance for hyacinths to float on the
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surface. This did not allow the light to shine through to the water onto
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the plants which the fish feeded on. The plants were unable to perform
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photosynthesis, and the fish died also because there was a lack of food. In
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the lack of sun the waterweeds grew and threaten to create diseases such as
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malaria, where the whole lake's ecosystem would die out.8 Many little
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animals and plants which were never discoved and may have had high economic
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value were to be lost forever.
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There remains a problem with reservoirs which to date hasn't been solved
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yet. A reservoir is a to store water, mainly for hydroelectric power or
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irrigation. Nearly 10 000 caribou drowned while crossing the inflated
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Caniapiscau River in September 1984, because of these reserviors. The heavy
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rainfall created enough water to overtop the structure and caused extra
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amounts of spillages in the reservoir. The water flooded the river while
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the caribou were literally submerged.9
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The Colarado River, known as the most litigated, controlled and lesgislated
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river in the world. People who used to raft there now say it is very insafe
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because of the fluctuating surges of water meant to accomodate when the people
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use most energy. What was fresh water is now being converted to salty water
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because of these reservoirs. The water standing in the reservoir evaporates
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when not used and the rest of the water becomes more salty.10
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There is another theory that dams are causing earthquakes, when these large
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structures are placed with the mass of the unnatural weight of the lake near
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it, this disrupts the Earth's surface and is a new precaution where before it
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was never heard of. Many people say that dams protect people from natural
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disasters, but there are some which it can intensify. For instance if an
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Earthquake happens then, along with cracks in the ground, buildings falling,
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there would also be a flood and large pieces of the broken dam to cope with.11
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Dams are harming the environment that people live in. What was being hailed
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as great accomplishments are now showing signs of great consquence. The
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preservation of our environment is the key to the preservation of people. We
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cannot exchange money for the deterioration of our own animals, plants and
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land. The is the environmental age and humans must respond by changing their
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ways and looking at the long-term prospect instead of the short-term. Until we
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as the users and protectors of the land can do this, future of our great human
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civilization will continue to look grim.
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