Grade 10 GeographyUnits 12, 13, 14 Essay – Effects of Dam Building Many people have already dammed a small stream using sticks and mud bythetime they become adults. Humans have used dams since early civilization,because four-thousand years ago they became aware that floods and droughtsaffected their well-being and so they began to build dams to protectthemselvesfrom these effects.1 The basic principles of dams still apply today as theydidbefore; a dam must prevent water from being passed.
Since then, people havebeen continuing to build and perfect these structures, not knowing the fullintensity of their side effects. The hindering effects of dams on humansandtheir environment heavily outweigh the beneficial ones. The paragraphsbelowwill prove that the construction and presence of dams always has and willcontinue to leave devastating effects on the environment around them. Firstly, to understand the thesis people must know what dams are. A damis abarrier built across a water course to hold back or control water flow.Damsare classified as either storage, diversion or detention. As you couldprobablynotice from it’s name, storage dams are created to collect or hold waterforperiods of time when there is a surplus supply. The water is then used whenthere is a lack of supply.
For example many small dams impound water in thespring, for use in the summer dry months. Storage dams also supply a watersupply, or an improved habitat for fish and wildlife; they may store waterforhydroelectricity as well. A diversion dam is a generation of a commonly constructed dam which isbuiltto provide sufficient water pressure for pushing water into ditches, canalsorother systems. These dams, which are normally shorter than storage dams areused for irrigation developments and for diversion the of water from astreamto a reservoir. Diversion dams are mainly built to lessen the effects offloodsand 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-overflowdams are built not to be overtopped, and they may include earth or rock intheir body.
Often, two types of these dams are combined to form a compositestructure consisting of for example an overflow concrete gravity dam, thewaterthat overflows into dikes of earthfill construction. A dam’s primary function is to trap water for irrigation. Dams help todecrease the severity of droughts, increase agricultural production, andcreatenew lands for agricultural use.
Farmland, however, has it’s price; riverbottomlands flooded, defacing the fertility of the soil. This agriculturallandmay also result in a loss of natural artifacts. Recently in Tasmania wherehasbeen pressure from the government to abandon the Franklin project whichwouldconsume up to 530 sq miles of land listed on the UN World Heritageregister. Inthe land losses whole communties must leave everything and start againelsewhere. The James’s Bay Hydroelectric project, hailed to be one of the mostambitious North American undertaking of dams was another example of thelandsthat may be lost.
The 12.7 billion scheme was to generate 3 160 megawattsofelectricity a day, this power output would be enough to serve a city of700,000! One of the largest problems with this dam, is that it would bebuilton a region that meant a lot to 10 500 Cree and 7 000 Inuit. Lands thattheirancestors have hunted and lived on for more than 5 000 years will befloodedalong with 90% of their trapping lines.6 If this happened these people mustresettle, find a new way of life and face the destruction of a piece oftheirheritage if this project is approved. When a dam is being constructed, the river where it is supposed to bebuilton must be drained. This kills much of the life and disrupts the ecosystemandpeaceful being of all the aquatic and terrestrial animals around it.
Atfisheries there is a large impact on the fish. The famous Columbia Riversawit’s stock of salmon drop considerably after the dams were built, althoughthere were fish ladders built. The salmon were unable to swim upstream whenitwas time for breeding as they usually did.
But perhaps it is the plans for the Amazon Basin in Brazil that shows ushowlarge the side-effects can be. In the city Surinam, in northern Brazil,LakeBrokopondo was created in 1864 swamping about 580 square miles of virginrainforest. Foul smelling gas called hydrogen sulfide was produced as thetreesdecomposed.
The turbine casings were attacked by the acidic water and Thedecayof water allowed a chance for hyacinths to float on the surface. This didnotallow the light to shine through to the water onto the plants which thefishfeeded on. The plants were unable to perform photosynthesis, and the fishdiedalso because there was a lack of food. In the lack of sun the waterweedsgrewand threaten to create diseases such as malaria, where the whole lake’secosystem would die out.
8 Many little animals and plants which were neverdiscoved and may have had high economic value were to be lost forever. There remains a problem with reservoirs which to date hasn’t been solvedyet. A reservoir is a to store water, mainly for hydroelectric power orirrigation. Nearly 10 000 caribou drowned while crossing the inflatedCaniapiscau River in September 1984, because of these reserviors. The heavyrainfall created enough water to overtop the structure and caused extraamounts of spillages in the reservoir.
The water flooded the river whilethecaribou were literally submerged.9 The Colarado River, known as the most litigated, controlled andlesgislatedriver in the world. People who used to raft there now say it is very insafebecause of the fluctuating surges of water meant to accomodate when thepeopleuse most energy. What was fresh water is now being converted to salty waterbecause of these reservoirs. The water standing in the reservoir evaporateswhen not used and the rest of the water becomes more salty.10 There is another theory that dams are causing earthquakes, when theselargestructures are placed with the mass of the unnatural weight of the lakenearit, this disrupts the Earth’s surface and is a new precaution where beforeitwas never heard of. Many people say that dams protect people from naturaldisasters, but there are some which it can intensify.
For instance if anEarthquake happens then, along with cracks in the ground, buildingsfalling,there would also be a flood and large pieces of the broken dam to copewith.11 Dams are harming the environment that people live in. What was beinghailedas great accomplishments are now showing signs of great consquence. Thepreservation of our environment is the key to the preservation of people.Wecannot exchange money for the deterioration of our own animals, plants andland. The is the environmental age and humans must respond by changingtheirways and looking at the long-term prospect instead of the short-term.
Untilweas the users and protectors of the land can do this, future of our greathumancivilization will continue to look grim.