My report is on the effects of dams on their ecosystem, such as, how dams effect the animals and aquatic life around these giant structures, causing them to move to a new habitat.
Dams also disrupt many other things than animals and aquatic life though; they also destroy mosses, plants, and trees because of the massive buildup of water behind the dams, which floods the land near them.
Since early civilization humans became aware that floods and droughts greatly affected their lives. So they began to build dams to protect themselves from these effects.
A dam's primary function is to trap water for irrigation. Dams help to decrease the severity of droughts, increase agricultural production, and are also used regularly to flood soil to make it fertile for agricultural use.
Since four-thousand years ago, people have been continuing to build and perfect dams, not knowing the full potential of their side effects. Unfortunately the side effects of dams on humans and their environment greatly outweigh the beneficial ones.
When a dam is being constructed, the river where it is supposed to be built on must be drained. This kills much of the life and disrupts the ecosystem and of all the aquatic and terrestrial animals around it. The largest impact is on the fish in the river. Such as the famous Columbia River, which saw it's stock of salmon drop dramatically after the all dams were built. There were also fish ladders built, but the salmon were still unable to swim upstream when it was time for breeding.
The basic principles of dams still exist today; a dam must prevent water from being passed through it. A dam is a barrier built across a water course to hold back or control water flow. Dams are classified as either storage, diversion or detention. Storage dams collect or hold water for periods of time when there is a surplus supply. The water is then used when there is a lack of supply. For example, many small dams holdback water in the spring for use in the summer’s dry months. Storage dams can also be used for recreational uses, or they can be an improved habitat for fish and wildlife. They may also be used to store water for hydroelectricity as well.
Diversion dams are normally shorter than storage dams and are mainly built to lessen the effects of floods and to trap sediment, but can also be used for different purposes. For instance, they can be used to provide sufficient water pressure for pushing water into ditches, canals or other systems for irrigation developments. Or you can also use them to be a diversion of water from a stream to a reservoir.
Overflow dams are designed to let the water flow over their crests, because of this they must be made of materials which do not erode. Non-overflow dams are also built to not overflow, and they are often made of materials that include earth or rock in their body. Often these two types of dams are combined to form a composite structure, for example, an overflow concrete gravity dam, which the excess water overflows into dikes of earth.
A reservoir stores water, mainly for hydroelectric power or irrigation. But there’s still one problem associated with them that remains unsolved to the date. The problem is that nearly 10,000 caribou drowned while crossing the gorging Caniapiscau River in September 1984, because of these reservoir’s. What happened is that they had a heavy rainfall, which created enough water to overflow the structure and caused the excess amounts of water to spill over into the reservoirs. This water flooded the river while the caribou were caught in the middle of it and got submerged under the water.
In 1995, Tasmania had pressure from the government to abandon the Franklin dam project, which would consume up to 530 square miles of land listed on the UN World Heritage register. Also if the dam would have been built, it would have resulted in whole communities that would have had to leave.
But the biggest problem that was created by a dam was at the Amazon Basin in Brazil. In the city Surinam, in northern Brazil, Lake Brokopondo was created in 1864 swamping about 580 square miles of virgin rainforest. This caused a foul smelling gas called hydrogen sulfide, which was produced as the trees started to decomposed. Light was also unable to shine through the water onto the plants which the fish fed on. So the plants were unable to perform photosynthesis, and the fish died also because of the lack of food. Because of the lack of sun waterweeds grew instead and threaten to spread diseases such as malaria thus the whole lake's ecosystem would die out. Many little animals and plants which were never discovered may have had high economic value but were lost forever.
There is another theory that dams cause earthquakes, when these large structures are placed with a great mass of unnatural weight near a lake, it disturbs the Earth's surface creates earthquakes.
Many people say that dams protect people from natural disasters, but it can also have the reverse effect and can intensify some. For instance, if an Earthquake happens and a dam broke there would not only be cracks along the ground and buildings falling, there would also be a flood and large pieces of the broken dam floating down the river too.
Sadly dams are harming the environment. What once was a great accomplishment has now turned out to be a great consequence. No amount of money can replace the animals, plants and land. We cannot replace what we have destroyed since it is gone forever. Thus it is up to human to preserve the environment by changing their ways and looking at long-term prospectives instead of the short-term. If we want to preserve the environment for future generations, we must change our ways and find alternative uses instead of dams.
Dams. New York, NY: Ballantine Books Inc., 1994.
Dams. New York, NY: Viking Penguin Inc., 1994.
Dams. St. Paul, MN: West Publishing Company, 1995.
Ecosystems. Belmont, CA: Wadsworth Publishing Company, 1990.
Ecosystems. New York, NY: A Simon & Schuster Company, 1996.
History of Dams. New York, NY: Macmillan College Publishing Company, 1991.
Living In the Environment. New York, NY: Persea Book Inc., 1992.
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 (This is an example of a storage dam.) |
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 (This is an example of a arch gravity dam.) |
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 (This is an example of a storage dam.) |
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