Carl
By: Mike • Essay • 1,250 Words • March 18, 2010 • 1,015 Views
Carl
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 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 their
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