ecological impacts of dams & water diversions

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Ecological impacts of dams & water diversions By Liliana, Boris and Pavel 10/8

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Page 1: Ecological impacts of dams & water diversions

Ecological impacts of dams & water diversions By Liliana, Boris and Pavel 10/8

Page 2: Ecological impacts of dams & water diversions

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)

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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)

Page 5: Ecological impacts of dams & water diversions

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

• On areas downstream that lose sediment- construction of a dam blocks the flow of sediment downstream, leading to downstream erosion

• Impact of water diversions on volume of water downstream- -on water temperature, precipitation, evaporation• Impact on river recreation- river banks are lost & damaged; narrowed

• Impact on displaced people (who lived/worked where the reservoir floods-> mass relocation, over 40 million have lost their homes (3) and (5)

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Example 1: The Colorado River• Map of the Hoover Dam on the Colorado River

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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 Hoover’s massive role in its construction as a engineer, secretary of commerce and president of the United States

(2) and (4)

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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)

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The Hoover Dam

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Example 2: The Nile

River

• Map of the Aswan High Dam

Page 11: Ecological impacts of dams & water diversions

The Aswan High Dam• Built in 1960 by Egypt with Soviet funding and machinery• General name fro two dams• Built because the old dam couldn’t 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 ½ of the power for Egypt

• Also, it protects 95% of the population of Egypt from floods (2) and (4)

Page 12: Ecological impacts of dams & water diversions

The Aswan High Dam

• Picture of the Aswan High Dam here

Page 13: Ecological impacts of dams & water diversions

Works Cited Page1) Army Corps of Engineers - New England District. Web. 06 June 2010.

<http://www.nae.usace.army.mil/recreati/bwd/bwdfc.htm>. 2)":::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE

DAMS ::::::::::::::." :::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE DAMS ::::::::::::::::. Web. 06 June 2010. <http://www.icold-cigb.net/pagearticle.aspx?ssmenu=310>.

3)"DAMS FROM THE ROMAN ERA IN SPAIN." T R A I A N V S. Web. 06 June 2010. <http://www.traianvs.net/textos/presas_in.htm#_ednref4>.

4)Size, Their Very. "Planete-tp : All about Public Works - Dams General." Planete TP : Tout Sur Les Travaux Publics. Web. 06 June 2010. <http://www.planete-tp.com/en/rubrique.php3?id_rubrique=62>.

 5)"Environmental Impacts." Burma Rivers Network. Web. 06 June 2010. <http://www.burmariversnetwork.org/key-concerns/environmental-impacts.html>.

Pictures:http://www.americansouthwest.net/maps/hoover-dam-map.gifhttp://www.tourwestamerica.com/Uploads/HooverDam.jpghttp://www.mbarron.net/Nile/OWENFALL.JPGhttp://www.planetware.com/i/map/EGY/south-of-aswan-map.jpghttp://dnr.wi.gov/org/water/wm/dsfm/dams/images/parts2.jpg