Desertification

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Desertification in the Sahel

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Desertification

  1. 1. Desertification Chesterton Community College GCSE Geography
  2. 2. What is desertification? <ul><li>Desertification occurs where land is turned into desert. </li></ul><ul><li>It occurs mainly in semi-arid lands which border the world’s major deserts. </li></ul>
  3. 3. Which areas are vulnerable? <ul><li>Vulnerability: Red = very high Orange = high Yellow = moderate </li></ul>
  4. 4. The area of greatest risk: The Sahel South of the Sahara desert / North of the savanna grasslands
  5. 5. What is The Sahel like? <ul><li>Semi-arid area. </li></ul><ul><li>Periods of rainfall and drought. </li></ul><ul><li>Supports small bushes. </li></ul><ul><li>Windbattered trees. </li></ul>
  6. 6. Physical reasons for desertification in The Sahel <ul><li>1950/60’s - above average rainfall, causing nomadic herders to settle and farmers to intensify agriculture. </li></ul><ul><li>1970’s - below average rainfall leading to extreme drought. Crops and animals die. Desert advances. </li></ul>
  7. 7. Desertification: an animation With thanks to Staffordshire County Council
  8. 8. Causes of desertification Vegetation roots bind soil. Vegetation dies. Soil is left exposed. Sun bakes the soil and it cracks. Wind blows away soil. No leaves to intercept rain. Soil is washed away. The soil is degraded, losing fertility and structure.
  9. 9. Human reasons for land degradation <ul><li>Traditional nomadic tribes settle in one place. Vegetation no longer protects the soil. </li></ul><ul><li>Trees provided protection for the soil, from wind and rain. </li></ul><ul><li>The growing of cash crops, depletes the soil fertility of the area. The soil structure breaks down. </li></ul>Overgrazing. Cutting down trees. Intensive agriculture. ‘ Desertification’ - caused by climate change. ‘Land degradation’ - caused by human activity
  10. 11. Physical impacts of desertification <ul><li>Soil erosion. </li></ul><ul><li>Sun baked, cracked soil. </li></ul><ul><li>Loss of plants and animals. </li></ul><ul><li>Gullying. </li></ul><ul><li>Dry rivers. </li></ul><ul><li>Growth of desert. </li></ul><ul><li>Increase in sand storms. </li></ul><ul><li>Flash floods. </li></ul>
  11. 12. Human impacts of desertification <ul><li>Crops and cattle die, resulting in famine. </li></ul><ul><li>Death. </li></ul><ul><li>Migrants move to cities, resulting in the growth of informal settlements, shanties, in already massively overpopulated urban areas. </li></ul>
  12. 13. Tackling desertification <ul><li>Plant Trees. </li></ul><ul><li>Roots bind the soil together. Leaves provide shade, and intercept water. </li></ul><ul><li>Cheap, long term. </li></ul><ul><li>Provide fuel wood and building materials. </li></ul>
  13. 14. Tackling desertification <ul><li>Terracing. </li></ul><ul><li>Prevent rainfall from washing away topsoil and nutrients. </li></ul><ul><li>Cheap to build, only man power needed. </li></ul>
  14. 15. Tackling desertification <ul><li>Magic Stones. </li></ul><ul><li>Similar to terracing, stones are placed along contours. </li></ul><ul><li>Topsoil can not be washed past the stones. Water infiltrates, instead of running over the surface. </li></ul><ul><li>Cheap to build, only man power needed. </li></ul><ul><li>Effective, shown to increase yields by 50%. </li></ul>
  15. 16. Magic stones! <ul><li>Click here if using the PowerPoint at school </li></ul><ul><li>Click here if using the PowerPoint online </li></ul>
  16. 18. Your tasks: Desertification in the Sahel <ul><li>Explain what desertification means. </li></ul><ul><li>Draw a sketch map of Africa to show the Sahel. </li></ul><ul><li>Name 6 Sahel countries on your map. </li></ul><ul><li>Make notes about the causes of desertification - physical and human factors (see pgs 140-141 Geog.GCSE). </li></ul><ul><li>Explain what is meant by the ‘spiral into desertification’. Use the diagram on page 141 to help you. </li></ul><ul><li>Make notes about ways of managing the land sustainably in the Sahel. Use sub-headings or bullets. </li></ul><ul><li>Extension task: Use the flow-chart diagram. Try to add arrows to it to show how each of the factors are linked in causing desertification. </li></ul>

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