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Drought Ap

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  • 1. What is drought?
    • There are many definitions, but usually it is a period of time where there is much less than average rainfall.
    • What do you think factors affect drought in a country? Can you list some ideas?
  • 2. What factors affect drought?
    • Wealth
    • Population
    • Temperature
    • Rainfall
    • Run-off rates
    • Land use
    • … these are found on p96 PTT
  • 3. How does drought affect MEDC’s?
    • Fall in river levels
    • Reduced water supply
    • Hosepipe bans
    • Damage housing foundations
    • Fire risk
    • Crop failure
    • Reduced water for industries (needed for cooling in processing)
  • 4. Can drought be controlled?
    • Reduce the causes of drought
    • Cope with drought
      • Improve prediction, e.g. satellite warning.
      • Provide food aid sooner, especially to small scale farmers.
      • Build large reservoirs and deeper wells.
    • Live with drought
      • Improve farming methods, e.g. AGRHYMET
      • Stop desertification.
  • 5. English drought
    • http://search.bbc.co.uk/cgi-bin/search/results.pl?tab=av&q=uk%20drought&recipe=all&scope=all&edition=
  • 6. Drought in the Sahel- LEDC case study
    • The Sahel is the narrow belt of semi-arid land on the edge of the Sahara desert in Africa.
    • Sahel literally means ‘edge of the desert’.
    • It is famous for the severe droughts it suffers.
  • 7. The causes of the drought are quite unique
    • In rain years, the Sahel receives just enough to prevent the droughts from causing a disaster…
    Position of the ITCZ on 21 June Strong south-westerly rain-bearing winds
  • 8. The causes of the drought are quite unique
    • But in drought years, the ITCZ doesn’t move as north as it should, due to global climatic patterns and this prevents the south-westerly winds bringing the usual rain.
    Position of the ITCZ on 21 June Weak south-westerly rain-bearing winds
  • 9. Human causes of drought in the Sahel
    • Desertification- is the spread of desert-like conditions in arid or semi arid areas dues to human influence or climate change. It is very hard to get the land back to its original condition.
    • http://www.green.tv/unep_global_desertification_outlook
    • Overcultivation- when arable agriculture has taken the nutrients out of the soil and it is over-used. The soil then becomes useless, and dry and is easily eroded by wind or water
    • Overgrazing- when there are too many cattle for the land to support them. They eat all of the vegetation that protect the soil and so erosion occurs.
    • Annotate your spiral diagrams on p25 to show these causes.
  • 10. What are the effects of drought in the sahel??
    • List as many as possible
  • 11. Living with drought in the Sahel and preventing desertification
    • Build dams to improve water storage for dry periods.
    • Introduce new drought-resistant crops as in Nigeria
    • Build earth traps to prevent soil from being washed away
    • Start afforestation schemes (will increase interception and reduce overland flow, and prevent erosion
    • The best solutions are small scale, low cost of appropriate technology.
  • 12. How can we reduce the effects of drought in MEDC’s and LEDC’s?
    • 1) Reduce the costs of drought.
    • 2) Cope with drought.
    • 3) Live with drought.

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