Many people have already dammed a small stream using sticks and mud .
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 thier .
crests, because of this they must be made of materials which do not .
