ecological impacts of dams & water diversions

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  • Ecological impacts of dams & water diversions By Liliana, Boris and Pavel 10/8
  • What are dams?
    • Definition of a dam- a solid barrier, constructed at a suitable location across a river valley to store flowing water.
    • Purpose of dams- to obtain hydropower, for irrigation, water for dom. consumption, flood and drought control, for navigational facilities & other uses- ex: developing fisheries
    • Earliest Dams- Mesopotamia & the Middle East
    • -first known dam in Jawa, Jordan gravity dam-flood control
    • -dated to 3000BC (1) and (2)
  • A little more about dams
    • Types of dams: differ by size or structure & material
    • -size: high dams >15-20m. , major dams: >150m.
    • -structure: timber dams, embankment dams, masonry dams (with subtypes) and arch-gravity dams.
    • Positive impacts of dams- benefitting humans:
    • on agriculture, water, damage prevention and power
    • Negative Impacts of Dams-
    • harmful impact on nature, wildlife, rare species and geology (change of water flow) (1) and (4)
  • Negative Impacts
    • Impact on fish- failure in breeding cycles and migration
    • On wetland species- dams reduce the amount of downstream sediments available to replenish coastal wetlands
    • On water quality- dams release poorly oxygenated water; garbage often accumulated by dams
    • O n areas downstream that lose sediment - construction of a dam blocks the flow of sediment downstream, leading to downstream erosion
    • I mpact of water diversions on volume of water downstream -
    • -on water temperature, precipitation, evaporation
    • I mpact on river recreation - river banks are lost & damaged; narrowed
    • I mpact on displaced people (who lived/worked where the reservoir floods -> mass relocation, over 40 million have lost their homes (3) and (5)
  • Example 1: The Colorado River
    • Map of the Hoover Dam on the Colorado River
  • The Hoover Dam
    • Built from 1931 to 1936 by the USA
    • Purpose to produce electricity and to control floods
    • Type gravity arch dam
    • Initially called The Boulder Dam but renamed to The Hoover Dam due to Hoovers massive role in its construction as a engineer, secretary of commerce and president of the United States
    • (2) and (4)
  • The Hoover Dam
    • Positive impact Production of electricity; control over floods; water for irrigation
    • Negative impact increase of salinity in parts of the Colorado river; four types of fish living only in the Colorado river now marked as endangered; erosion occurring on the Colorado river; river bed level dropping
    • What depends on it? the power from several states and lots of irrigation for farms
    • Also 112 workers died building the Hoover Dam 95 of them from pneumonia caused by carbon monoxide poisoning
    • (2) and (4)
  • The Hoover Dam
  • Example 2: The Nile River
    • Map of the Aswan High Dam
  • The Aswan High Dam
    • Built in 1960 by Egypt with Soviet funding and machinery
    • General name fro two dams
    • Built because the old dam couldnt contain the incoming water
    • Negative impacts crops relaying on the floods now relay on artificial fertilizers leading to poor soils; parasitic diseases increase; loss of sediment the Nile delta disappearing; 90 000 people had to be moved
    • - increasingly salty agricultural soils because of altered river flow and loss of river nutrients into the Mediterranean Sea
    • Positives impacts no floods; steady water flow; provides of the power for Egypt
    • Also, it protects 95% of the population of Egypt from floods
    • (2) and (4)
  • The Aswan High Dam
    • Picture of the Aswan High Dam here
  • Works Cited Page
    • 1) Army Corps of Engineers - New England District . Web. 06 June 2010. .
    • 2)":::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE DAMS ::::::::::::::." :::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE DAMS :::::::::::::::: . Web. 06 June 2010. .
    • 3)"DAMS FROM THE ROMAN ERA IN SPAIN." T R A I A N V S . Web. 06 June 2010. .
    • 4)Size, Their Very. "Planete-tp : All about Public Works - Dams General." Planete TP: Tout Sur Les Travaux Publics . Web. 06 June 2010. .
    • 5)"Environmental Impacts." Burma Rivers Network . Web. 06 June 2010. .
    • Pictures: