Ecological impacts of dams & water diversions


Published on

Published in: Technology
  • Be the first to comment

Ecological impacts of dams & water diversions

  1. 1. Ecological impacts of dams & water diversions By Liliana, Boris and Pavel 10/8
  2. 2. What are dams? <ul><li>Definition of a dam- a solid barrier, constructed at a suitable location across a river valley to store flowing water. </li></ul><ul><li>Purpose of dams- to obtain hydropower, for irrigation, water for dom. consumption, flood and drought control, for navigational facilities & other uses- ex: developing fisheries </li></ul><ul><li>Earliest Dams- Mesopotamia & the Middle East </li></ul><ul><li>-first known dam in Jawa, Jordan – gravity dam-flood control </li></ul><ul><li>-dated to 3000BC (1) and (2) </li></ul>
  3. 4. A little more about dams <ul><li>Types of dams: differ by size or structure & material </li></ul><ul><li>-size: high dams >15-20m. , major dams: >150m. </li></ul><ul><li>-structure: timber dams, embankment dams, masonry dams (with subtypes) and arch-gravity dams. </li></ul><ul><li>Positive impacts of dams- benefitting humans: </li></ul><ul><li>on agriculture, water, damage prevention and power </li></ul><ul><li>Negative Impacts of Dams- </li></ul><ul><li>harmful impact on nature, wildlife, rare species and geology (change of water flow) (1) and (4) </li></ul>
  4. 5. Negative Impacts <ul><li>Impact on fish- failure in breeding cycles and migration </li></ul><ul><li>On wetland species- dams reduce the amount of downstream sediments available to replenish coastal wetlands </li></ul><ul><li>On water quality- dams release poorly oxygenated water; garbage often accumulated by dams </li></ul><ul><li>O n areas downstream that lose sediment - construction of a dam blocks the flow of sediment downstream, leading to downstream erosion </li></ul><ul><li>I mpact of water diversions on volume of water downstream - </li></ul><ul><li>-on water temperature, precipitation, evaporation </li></ul><ul><li>I mpact on river recreation - river banks are lost & damaged; narrowed </li></ul><ul><li>I mpact on displaced people (who lived/worked where the reservoir floods -> mass relocation, over 40 million have lost their homes (3) and (5) </li></ul>
  5. 6. Example 1: The Colorado River <ul><li>Map of the Hoover Dam on the Colorado River </li></ul>
  6. 7. The Hoover Dam <ul><li>Built from 1931 to 1936 by the USA </li></ul><ul><li>Purpose – to produce electricity and to control floods </li></ul><ul><li>Type – gravity arch dam </li></ul><ul><li>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 </li></ul><ul><li>(2) and (4) </li></ul>
  7. 8. The Hoover Dam <ul><li>Positive impact – Production of electricity; control over floods; water for irrigation </li></ul><ul><li>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 </li></ul><ul><li>What depends on it? – the power from several states and lots of irrigation for farms </li></ul><ul><li>Also 112 workers died building the Hoover Dam 95 of them from pneumonia caused by carbon monoxide poisoning </li></ul><ul><li>(2) and (4) </li></ul>
  8. 9. The Hoover Dam
  9. 10. Example 2: The Nile River <ul><li>Map of the Aswan High Dam </li></ul>
  10. 11. The Aswan High Dam <ul><li>Built in 1960 by Egypt with Soviet funding and machinery </li></ul><ul><li>General name fro two dams </li></ul><ul><li>Built because the old dam couldn’t contain the incoming water </li></ul><ul><li>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 </li></ul><ul><li>- increasingly salty agricultural soils because of altered river flow and loss of river nutrients into the Mediterranean Sea </li></ul><ul><li>Positives impacts – no floods; steady water flow; provides ½ of the power for Egypt </li></ul><ul><li>Also, it protects 95% of the population of Egypt from floods </li></ul><ul><li>(2) and (4) </li></ul>
  11. 12. The Aswan High Dam <ul><li>Picture of the Aswan High Dam here </li></ul>
  12. 13. Works Cited Page <ul><li>1)  Army Corps of Engineers - New England District . Web. 06 June 2010. <>. </li></ul><ul><li>  2)&quot;:::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE DAMS ::::::::::::::.&quot; :::::::::::::::: ICOLD : INTERNATIONAL COMMISSION OF LARGE DAMS :::::::::::::::: . Web. 06 June 2010. <>. </li></ul><ul><li>3)&quot;DAMS FROM THE ROMAN ERA IN SPAIN.&quot; T R A I A N V S . Web. 06 June 2010. <>. </li></ul><ul><li>4)Size, Their Very. &quot;Planete-tp : All about Public Works - Dams General.&quot; Planete TP : Tout Sur Les Travaux Publics . Web. 06 June 2010. <>. </li></ul><ul><li>  5)&quot;Environmental Impacts.&quot; Burma Rivers Network . Web. 06 June 2010. <>. </li></ul><ul><li>Pictures: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>