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Effects of Dam Building


Many people have already dammed a small stream using sticks
and mud by 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.1 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
heavily outweigh the beneficial ones. The paragraphs below
will prove that the construction and presence of dams
always has and will continue to leave devastating effects
on the environment around them.
Firstly, to understand the thesis people must know what
dams are. 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. 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. Storage dams also
supply a water supply, or an improved habitat for fish and
wildlife; they may store water for hydroelectricity as
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.3
Overflow dams are designed to carry water which flow over
thier crests, because of this they must be made of
materials which do not erode. Non- overflow dams are built
not to be overtopped, and they may include earth or rock in
their body. Often, two types of these dams are combined to
form a composite structure consisting of for example an
overflow concrete gravity dam, the water that overflows
into dikes of earthfill construction.4
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. Recently in Tasmania where has been pressure
from the government to abandon the Franklin project which
would consume up to 530 sq miles of land listed on the UN
World Heritage register. In the land losses whole
communties must leave everything and start again elsewhere.5
The James's Bay Hydroelectric project, hailed to be one of
the most ambitious North American undertaking of dams was
another 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. 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.6 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. 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.7
But perhaps it is the plans for the Amazon Basin in Brazil
that shows us how large the side-effects can be. In the
city Surinam, in northern Brazil, Lake Brokopondo was
created in 1864 swamping about 580 square miles of virgin
rainforest. Foul smelling gas called hydrogen sulfide was
produced as the trees decomposed. The turbine casings were
attacked by the acidic water and the decay of water allowed
a chance for hyacinths to float on the surface. This did
not allow the light to shine through to the water onto the
plants which the fish feeded on. The plants were unable to
perform photosynthesis, and the fish died also because
there was a lack of food. In the lack of sun the waterweeds
grew and threaten to create diseases such as malaria, where
the whole lake's ecosystem would die out.8 Many little
animals and plants which were never discoved and may have
had high economic value were to be lost forever.
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 reserviors. The
heavy rainfall created enough water to overtop the
structure and caused extra amounts of spillages in the
reservoir. The water flooded the river while the caribou
were literally submerged.9
The Colarado River, known as the most litigated, controlled
and lesgislated river in the world. People who used to raft
there now say it is very insafe because of the fluctuating
surges of water meant to accomodate 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.10
There is another theory that dams are causing earthquakes,
when these large structures are placed with the mass of the
unnatural weight of the lake near it, this disrupts the
Earth's surface and is a new precaution where before it
_was never heard of. 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.11
Dams are harming the environment that people live in. What
was being hailed as great accomplishments are now showing
signs of great consquence. 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. The 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 civilization will continue to look grim. 


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