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Реферат: Dams And Their Effects Essay Research Paper

Название: Dams And Their Effects Essay Research Paper
Раздел: Топики по английскому языку
Тип: реферат Добавлен 09:06:23 08 ноября 2010 Похожие работы
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Dams And Their Effects Essay, Research Paper

The Effects of River Damming

Water, the life blood of the planet earth. With out water, the earth s high variety of life could have never been created. Ever since history has been recorded, man has constructed society around water as a resource. As technology and science increased; civilizations created new ways to store and manage water, this new knowledge came a the production of dams.

Many people have already dammed a small stream using sticks and muddy the time they become adults. Humans have used dams since early civilization, because four-thousand years ago they became aware that floods and droughts affected their well-being and so they began to build dams to protect themselves from these effects. The basic

principles of dams still apply today as they did before; a dam must

prevent water from being passed. Since then, people have been

continuing to build and perfect these structures, not knowing the full

intensity of their side effects. The hindering effects of dams on

humans and their environment seem to outweigh the beneficial ones. As humans and the living organisms remaining today go through time, something is going to have to be done to better balance the effects of dams.

Dams are classified as either storage, diversion or detention. As you could probably notice from it’s name, storage dams are created to 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 impound water in the spring, for use in the summer dry months. This in fact is one great aspect of damming. The waters taken from a dam or reservoir gives a break to the underground storage of water in aquifers pumped out by wells. The wells could eventually deplete the water level enough to cause a sink hole with major environmental damage. Storage dams also supply a water supply, or an improved habitat for fish and wildlife; they may store water for hydroelectricity as well.

A diversion dam is a generation of a commonly constructed dam which is built to provide sufficient water pressure for pushing water into ditches, canals or other systems. These dams, which are normally

shorter than storage dams are used for irrigation developments and for diversion the of water from a stream to a reservoir. Diversion dams are mainly built to lessen the effects of floods and to trap sediment.

A dam’s primary function is to trap water for irrigation. Dams

help to decrease the severity of droughts, increase agricultural

production, and create new lands for agricultural use. Farmland,

however, has it’s price; river bottomlands flooded, defacing the

fertility of the soil. This agricultural land may also result in a

loss of natural artifacts.

The James’s Bay Hydroelectric project, hailed to be one of the most ambitious North American undertaking of dams is an example of

the lands that may be lost. The 12.7 billion scheme was to generate 3,160 megawatts of electricity a day, this power output would be enough to serve a city of 700 000! One of the largest problems with this dam, is that it would be built on a region that meant a lot to 10 500 Cree and 7 000 Inuit natives. Lands that their ancestors have hunted and lived on for more than 5 000 years will be flooded along with 90% of their trapping lines. If this happened these people must resettle, find a new way of life and face the destruction of a piece of their heritage if this project is approved.

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 peaceful being of all the aquatic and terrestrial

animals around it. At fisheries there is a large impact on the fish. Throughout the last 150 years salmon populations have been continuously dropping, originally because of the rampant overfishing of the late 19th century, and currently because of habitat loss due to hydropower dams and poor logging practices. The primary intervention used to increase the salmon population has been hatcheries. It was thought that they would solve the problem of decreased salmon populations, hatcheries actually lead to the destruction and decline of wild salmon stocks. There are unfortunately many consequence now realized about salmon hatcheries. The famous Columbia River saw it’s stock of salmon drop considerably after the dams were built, although there were fish ladders built. The salmon were unable to swim upstream when it was time for breeding as they usually did.

There remains a problem with reservoirs which to date hasn’t been

solved yet. A reservoir is a to store water, mainly for hydroelectric

power or irrigation. Nearly 10 000 caribou drowned while crossing the

inflated Caniapiscau River in September 1984, because of these

reservoirs. The heavy rainfall created enough water to overtop the

structure and caused extra amounts of spillage in the reservoir. The

water flooded the river while the caribou were literally submerged.

The Colorado River, known as the most litigated, controlled and

legislated river in the world. People who used to raft there now say

it is very unsafe because of the fluctuating surges of water meant to

accommodate when the people use most energy. What was fresh water is

now being converted to salty water because of these reservoirs. The

water standing in the reservoir evaporates when not used and the rest

of the water becomes more salty.

Dams can also be a downfall to the sediments that need to be deposited down stream for soil nutrition. As the dam fills with water, the area of water near the dam begins to fill up with sediment from upstream. The sediment gets trapped inside the dam or reservoir and begins to fill the area up with soil; that costs numerous amounts of dollars to be dredged out and disposed of.

There is another theory that dams are being broken by earthquakes.

Many people say that dams protect people from natural disasters, but there are some which it can intensify. For instance if an Earthquake happens then, along with cracks in the ground, buildings falling, there would also be a flood and large pieces of the broken dam to cope with. Whole cities could be washed away without even a split second warning. One such town is West Marin. If a n earth quake knocks our Kent Lake or Nicasio Dams the town would be covered in 7 feet of water nearly instantly, while a surge that went up stream will soon come roaring down to totally consume the town.

Dams are harming the environment that people live in. What was

being hailed as great accomplishments are now showing signs of great

consequence. The preservation of our environment is the key to the

preservation of people. We cannot exchange money for the deterioration

of our own animals, plants and land. This is the environmental age and

humans must respond by changing their ways and looking at the

long-term prospect instead of the short-term. Until we as the users

and protectors of the land can do this, future of our great human

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