Dams How important are they?

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European Class 2005 Advantages of Dams By Avis
and Gemma
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Introduction

• What is a dam?
• A dam is an engineering structure built to
  block a valley or other low lying area for the
  purpose of storing water (Hancock and Skinner,
  2000).
• How many?
• From 1992 there was over 10 thousand dams
  worldwide.
• About 500 dams are being creating every year,
  which exceed 15metres in height. (Jiles and
  Spencer, 1995).

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Advantages of Dams
The main Advantages

• Regulate water flow and Flood Control
• Sediment Control
• Drought Control
• Time for endangered species to be moved
• To another suitable location.
• Irrigation
• Navigation Improvement
• Generation of hydro-electric power
• Can be made to suit geology, can be placed in
  narrow and
• Wide valleys. In rock or soil types.

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Flood and Flow Control

• 60 of total stream flow is regulated by dams
  and reservoirs for flood control (Jiles and
  Spencer, 1995).
• This is due to flood peaks being reduced, and the
  uniformity in base flow being increased
  throughout.

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Flood and flow Control
40 of rivers in Africa, Europe, North America
were stabilized by dams.
Below is a map showing the Europe dams.
Map taken from http//www.grid.unep.ch/product/publ
ication/freshwater_Europe/images/eurodam.jpg
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Sedimentary Control
There is a reduction as the naturally eroding
Cliffs now have basal protection. (Less fluvial
Inputs). Deposition location has changed,
sediment Is no longer built up in wetlands.
Resulting in less Erosion in drainage basins.
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Drought Control
Dams are needed in places of permanent Drought.
To act as barriers to hold drinking Water.
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Dams of the world

• They can be large
• They can be small
• With adaptations for fish (ladders and turbine
  guards)
• Without adaptations for fish

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Case study 1
Looking at three Gorges Dam scheme in China.
What were its advantages?

• Prevent flooding
• Hydro-power electricity
• Irrigation (agriculture)
• Domestic use
• Navigation

http//www.digitalglobe.com/images/qb/three_gorges
_dam_july13_2003_dg.jpg
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Case study 2
http//www.thirdworldcentre.org/aswpresa.jpg
Advantages of the aswam dam

• Prevent flood and drought catastrophic conditions
• For irrigation
• 4000km2s of dessert can now be used by farmers
• Floodplain has been converted from 1 crop
  rotation
• to 3 crop rotation.
• Hydro-electricity.
• Countries income has increased by 500 million per
  year
• Since it was built.

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Case study 3
Endangered species can be removed and put Into a
suitable habitat. This occurred with the Species
Percina tanasi (Snail darter minnow). However
the dam did not really affect the Population as
they were found naturally occurring In a near by
stream. This was at the site of Tellico Dam on
the Little Tennessee river in Tennessee
(Freeman, 1995).
http//bryonfreeman.com/v-web/gallery/albums/album
15/res374114578.jpg
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Transport on the River

• Ferry transportation began in 1860s, they now use
  barges
• Economical
• Consumer Benefits
• Relieves rail congestion

The Pacific Northwest Barge Industry on the
Columbia-Snake River System by American Waterways
Operation 1992-3 http//www.bluefish.org/pnbarge.h
tm
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DAMS How important are they?

• Provide water for transport

16 cents per bushel by barge
92 cents per bushel by truck
32 cents per bushel by rail (if available)
http//www.saveourdams.com
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Provide Electricity for the community Roll on
Columbia By Beth Gibson http//members.aol.com/Gi
bson0817/river.htm

• Columbia and Snake River supply 63 of hydro
  electric energy

• Grand Coulee when built provided work after great
  depression

• Brought cheap electricity to the area

• Helped with the war effort

• Later Industry moved to Pacific west because of
• cheap energy supply

http//www.deniskingphoto.com/coulee_dam/coulee_da
m3.html
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Ecology Friendly

• 96-98 pass safely through turbines

• Dams and turbines are not huge blenders

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Ecology Friendly
H\COLUMBIA RIVER BASIN - DAMS AND SALMON.htm

• Fish Barges are a partial solution

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A Commissioners Story
Les Wigen Whitman County Commissioner
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References

• Anon, 1998 acessed at http//www.grid.unep.ch/prod
  uct/publication/freshwater_Europe/images/eurodam.j
  pg
• Buchal James NG 60 Min
• http//www.saveourdams.com
• Gibson Beth Roll on Columbia By
• http//members.aol.com/Gibson0817/river.htm
• Hancock and Skinner, 2000, The oxford companion
  to the earth. Oxford University Press, Great
  Clarendon Street, Oxford.
• Park, C., 1997, The environment, 29 West 35th
  Street, New York.
• S Army Corps of Engineers, Northwestern Division
  POC Adele Merchant, Pacific Salmon Coordination,
  [phone]
• Page Updated Thursday September 05 2002
• H\COLUMBIA RIVER BASIN - DAMS AND SALMON.htm
• http//www.deniskingphoto.com/coulee_dam/coulee_da
  m3.html
• The Pacific Northwest Barge Industry on the
  Columbia-Snake River System by American Waterways
  Operation 1992-3
• http//www.bluefish.org/pnbarge.htm
• Spencer, T., and Jules, H. 1995, Coastal
  Problems, Oxford University Press Inc, 198
  Madison Avenue, New York.