Effects of Dam Building

Grade 10 Geography
Units 12, 13, 14
Essay – 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.

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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 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.


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.


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.


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.


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.