Floods and Droughts

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Floods and Droughts
Wow Thats dry!

• Chase Seale , Dustin Jee , Andrew Kim , Zachary
  Stanton

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Floods

• Flood is defined as extra water from rain,
  rivers, or oceans over land that is already
  saturated and cannot hold anymore water.
• 2 types of floods are broadside and flash floods.

This probably wont happen to you. So dont worry.
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Flash Floods
??So be prepared!!

• Flooding that occurs with little or no warning.
  They are becoming more common in cities where
  heavy rain cannot be drained quickly. They can
  also occur when a dam bursts or overflows ,
  allowing water or debris to take out buildings ,
  trees and many other objects.
• The most devastating flood in Canadian history
  struck the Sanguenay area of Quebec in the summer
  of 1996. It began raining on July 19th and on
  July 20th the water flowed over the walls of the
  dam , and a soil dike broke and flooding began.
  It caused 800 million dollars worth of damage.

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Broadside Floods

• Broadside floods are floods that cover large
  areas of land and can be predicted days or weeks
  before they occur.

Something like this.
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Major Floods

• Australia 1893 washed away Albert railway
  bridge
• N.S.W 1954- water flooded houses at great speed
• Egypt at least 5000 years bring silt from up
  the river that is used for fertile soil.

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Causes of Broadside Floods

• Delta areas of some rivers flood every year in
  Spring caused by melting in the mountains where
  the rivers originated. Examples of famous
  occurrences are the Nile River in Africa and the
  Yangtze River in China.
• Some rivers flood after a winter of heavy snow
  fall followed by heavy rains in the spring. The
  Red River flood in 1997 in Manitoba, which took
  weeks to peak was a devastating example.

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Flood Control
Its not easy as turning off a tap.

• Dams on rivers and lakes help to control
  flooding. Before expected heavy rains and winter
  runoff , conservation authorities lower the water
  levels in dammed lakes , allowing the water to
  flow away gradually in the drainage river. This
  creates space for storing large amounts of water.
• Building spillways and floodways are another way
  to control flooding. Spillways are canals that
  divert the access water from the regular flow of
  a river during a flood. The Red River floodway
  near Winnipeg helped save that city from major
  damage during 1997 flood.
• Greening is another type of flood control.
  Greening is planting a whole bunch of plants to
  absorb more water.

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Most Common Flood Locations

• United States
• Australia
• India/Indonesia
• France

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Droughts

• Drought is a natural event when theres very
  little rain or other precipitation.
• The areas at latitude 30 degree north and south
  of the equator are regions of high pressure where
  the average yearly rain fall is low. Ex. Wild
  fires in California.
• In the mid-latitude around 45 degree north/south
  of the equator, droughts may last several months
  or even years.

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Dust Bowl

• The most devastating drought in Canada happened
  in the mid 1930s in the prairies. During this
  time, topsoil blew off the farmland causing the
  name Dust Bowl All the farmers went broke.

This is what happened to the farmers
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Major droughts

• USA 1931-1938 severe wind storms
  dried out the land
• Australia 1982-1983 no rain for more than one
  year
• Britain 1976 did not rain from June, 1975, to
  September, 1976.
• Africa 1972-1974- Decreased rain fall

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References

• Science 10 Nelson Text by Bob Ritter, Donald
  Plumb, Frank Jenkins, Hans van Kessel and Alan J.
  Hirsch
• http//en.wikipedia.org/wiki/Flood
• http//en.wikipedia.org/wiki/drought