Dams are structures built across rivers or streams to impound water. The document discusses different types of dams such as concrete, gravity, arch, and buttress dams. While dams provide benefits like hydroelectric power and flood control, they can also have negative environmental impacts. Impacts include disrupting fish migration, altering water flows and temperatures downstream, and forcing relocation of human communities. The document also discusses specific dams like the Aswan Dam in Egypt and dams constructed on the Aral Sea.

1. DAMS http://www.cromwell.org.nz/aerial_photos/images/Clyde%20Dam_jpg.jpg http://www.centralbasin.org/blog/wp-content/uploads/2009/03/hoover-dam-directions.jpg http://www.goodlife.com.ng/uploads/Yeunde-Farinloye_120_dam1.gif http://www.destination360.com/north-america/us/nevada/las-vegas/images/s/las-vegas-hoover-dam.jpg http://www.physics.uiowa.edu/~umallik/adventure/nov_06-04/Grand%20Coulee%20Dam.jpg

2. Dam Structure http://www.americanwhitewater.org/photos/archive/medium/18665.jpg

3. Dam Structure 2 http://4.bp.blogspot.com/_GmlJ2al7e_k/Su2-BeKr25I/AAAAAAAAGwc/QsNga5IwUT8/s400/damgif

4. Dam Structure Impermeable Membrane Strength Outlet Valve Spillway http://www.parks.ca.gov/pages/500/images/folsomdam.jpg (5)

5. Types of Dams Concrete Gravity Arch & Buttress Fill (Embankment) Earth Earth & Rock Fill Concrete Faced Rock Fill (5)

6. Uses of Dams To provide H 2 O (towns/irrigation) To store waste (from mines) To generate electricity To help control floods (5)

7. Positive Sides of Dams 20% of electrical energy production Cheap energy Long life Attracting tourists (5)

8. Negative Impacts of Dams http://upload.wikimedia.org/wikipedia/commons/b/b5/Arch_dam_Oymapinar_%28Manavgat_River,_Turkey%29.JPG

9. Impacts on Water Diversion Upstream ->stationary reservoir: standing water for long periods 1 organic material-> decompose-> consume the limited oxygen-> dead zones 1 algae growth (toxic for rivers) 1 temperatures: too low at the bottom and too high on the surface no turnover 1

10. Downstream: Depends on the season-long periods without flow 2 Flow-high Energy of water- moves rocks, sand, sediments 1 Water- polluted, without oxygen, smells rotten (sulphurous hydrogen disposal) 2 The ecosystem-damaged 2

11. Impact on Fish 5 http://inadawords.com/wp-content/uploads/2008/01/nemo.jpg Dams prevent the migration: salmon ->river-> sea Fish cannot pass the dam ->not enough food-> die Slow moving water: many fish-> victims of predators No circulation (t is not balanced), not enough oxygen, toxic water ->death

12. Impacts on Human People have to abandon their home, agricultural lands, environment-> start living in a new way, adjust to new conditions 4 Collapse: lack of precise engineering 3 , too much rain 4 “ China is plagued by the world's worst dam hazards” (Minister Chen) , rainfalls, earthquakes 4

13. Immediate evacuation Causes: floods-> death of many people, environmental destructions 4 Living near dam-dangerous(esp. in China) 4 http://news.nationalgeographic.com/news/2005/08/photogalleries/New_Orleans_flood/images/primary/katrina28.jpg http://www.ecy.wa.gov/programs/wr/dams/Images/Taiwan_Dam_Failure_16Sta5_Dam.jpg

14. Aswan Dam http://geoeyemediaportal.s3.amazonaws.com/assets/images/gallery/manmade/structures/hires/aswan_dam.jpg http://upload.wikimedia.org/wikipedia/commons/6/6a/Lake_Nasser_location.png

15. Aswan Dam Aswan Dam is the general name for two dams – High and Low dam. Low – constructed in 1902 High – 1970 Aim = to increase the economic production trough regulating the annual river flooding http://farm1.static.flickr.com/111/295438443_40c30138e6.jpg (8)

16. Aswan Da m - Benefits Decreased the effect of the dangerous floods – 1964 and 1973 Increased the farmland drastically Powered a huge amount of the country (8)

17. Aswan Dam Enviromental and cultural problems Flooding lower Nubia Silt held back Logging soils Erosion Endangering historical sites (8)

18. Aral Sea D am http://upload.wikimedia.org/wikipedia/commons/8/85/Aral_map.png http://guanakolandia.files.wordpress.com/2010/04/mar-de-aral-aral-sea-dam_788415c.jpg

19. Aral Sea One of the biggest lakes on Earth Located in Central Asia between Kazakhstan, and Uzbekistan Dam project in 2005 in order to save the Aral Sea (7)

20. Aral Sea Nearly destroyed ecosystems! Health problems for people Almost no fishing industry http://upload.wikimedia.org/wikipedia/commons/9/95/Aral_Sea_1989-2008.jpg (7)

21. Last hope – the dam The last attempt to save the sea was to build a Dam Water lever raised by 12m Salinity was dropped Fishing rates raised again (7)

22. Work Cited 8. Antelava, Natalya. &quot;BBC NEWS | Asia-Pacific | Dam Project Aims to save Aral Sea.&quot; BBC NEWS | News Front Page . BBC, 9 Apr. 2007. Web. 14 June 2010. <http://news.bbc.co.uk/2/hi/asia-pacific/6538219.stm>. 6. Antelava, Natalya. “Dam project aims to save Aral Sea .” BBC News . BBC, 2010. Web. 14 June 2010. <http://news.bbc.co.uk/‌2/‌hi/‌asia-pacific/‌6538219.stm>. 3. Kelly, Peggy. “Cause of St. Francis Dam collapse more concrete than initially verified.” Santa Paula Times Online . Santa Paula Times, 2010. Web. 14 June 2010. <http://www.santapaulatimes.com/‌news/‌fullstory.php/‌aid/‌18775/‌Cause_of_St._Francis_Dam_collapse_more_concrete_than_initially_verified.html,>. 4. “More than 37,000 Chinese dams could collapse from excess rain.” AsiaNews.it . Autogestione contenuti di AsiaNews, 8 May 2009. Web. 14 June 2010. <http://www.asianews.it/‌news-en/‌More-than-37,000-Chinese-dams-could-collapse-from-excess-rain-15189.html>. 1. “Poorly Run Hydro.” Dam Effects . Hydropower Reform Coalition, 2009. Web. 14 June 2010. <http://www.dameffects.org/>. 2. Sait TAHM&#304;SC&#304;O&#286;LU, M., et al. “POSITIVE AND NEGATIVE IMPACTS OF DAMS.” DSI . N.p., 2007. Web. 14 June 2010. <http://www.dsi.gov.tr/‌english/‌congress2007/‌chapter_2/‌60.pdf>. 5. Smith, S. E. “Why are Dams Potentially Harmful to Fish?” Wise Geek . conjecture corporation , 12 Apr. 2010. Web. 14June 2010. <http://www.wisegeek.com/‌why-are-dams-potentially-harmful-to-fish.htm>. 7. &quot;The Kazakh Miracle: Recovery of the North Aral Sea.&quot; Environment News Service . Environment News Service (ENS), 1 Aug. 2008. Web. 14 June 2010. <http://www.ens-newswire.com/ens/aug2008/2008-08-01-01.asp>.