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  1. 1. Starter-think of 3 questions you would like to ask about this picture! What happened? When will it rain? Why me? Monday May 21 st 2007!
  2. 2. Lesson title: What is desertification? Aim: to understand the causes and effects of Desertification To be aware that humans can help stop/slow down the process
  3. 3. Process via which land turns into desert. Desertification is when a desert gradually spreads to the surrounding areas of semi-desert = Desertification
  4. 4. Where is it happening? Parts of Africa have been the worst affected areas, especially a region called The Sahel.
  5. 5. The Sahel stretches for 500km from Senegal and Mauritania on the west coast to Sudan and Ethiopia on the east. The region covers 1/5 th of Africa . The Sahel Sahara Desert Task- Draw a quick sketch of Africa in the space on your sheet- label and colour the Sahel and the Sahara desert to the North. Try to label some countries too! Parts of Africa have been the worst affected areas, especially a region called The Sahel. Ethiopia Niger Sudan
  6. 6. What is the Sahel like? <ul><li>Semi-arid (not as dry as desert but almost!) area only 300mm of rainfall-ALL IN 3 MONTHS- SOMETIMES THIS RAIN DOES NOT ARRIVE! </li></ul><ul><li>Periods of intense rainfall and drought. </li></ul><ul><li>Supports small bushes and trees. </li></ul><ul><li>Across between desert and Savanna </li></ul>
  7. 7. <ul><li>The Sahel regions are areas which experience </li></ul><ul><li>desertification. </li></ul>
  8. 8. <ul><li>Why does the Sahel suffer from desertification? </li></ul>DESERTIFICATION Increase in population Increase in cattle Deforestation for fire wood Grassland grazed more intensively Roots no longer hold soil together Roots may be eaten as well as grass Leaves no longer protect soil from weather Less vegetation means less protection from weather Loose top soil blown away by wind (Soil Erosion) = Loose top soil blown away by wind (Soil Erosion) = DESERTIFICATION
  9. 9. 1) below average rainfall leading to extreme drought,. meaning the people have little rain to make the soil full of moisture so little can be grown in it Natural causes 2) Climate is naturally getting warmer which is increasing temperatures and decreasing rainfall in the Sahel region
  10. 10. Humans are generally considered to be the main cause of Desertification, because of the way they abuse the land- Over farming Overgrazing Deforesting areas Increasing global Warming Human Reasons for Desertification in the Sahel.
  11. 11. <ul><li>Farmers have been forced to use the same land over and over again to grow crops. This has meant that the land has not had time to recover. The crops remove the goodness from the soil, leaving it dry and lacking in nutrients. Crops cannot be grown in such poor soil. </li></ul>OVERFARMING
  12. 12. OVERGRAZING <ul><li>Too many cattle have been grazing the land for food. Without plant roots to bind the soil together it is easily blown away. </li></ul>
  13. 13. DEFORESTATION <ul><li>People have had to chop down increased numbers of trees to use for fuel. This again has left the soil exposed to the elements! </li></ul>
  14. 14. <ul><li>Overgrazing. Traditional nomadic tribes settle in one place. Vegetation no longer protected the soil. </li></ul><ul><li>Cutting down trees . Trees provided protection for the soil, from wind and rain. </li></ul><ul><li>OVER FARMING . Too much farming ruins soil quality destroying nutrients meaning nothing grows in it </li></ul><ul><li>Deforestation- when trees are cut down the soil is more easily washed away when the little rain that falls does so </li></ul>Human Reasons for Desertification in the Sahel.
  15. 15. How does this lead to desert? Vegetation roots bind the soil. Vegetation dies. Soil is left exposed. Sun bakes the soil and it cracks. Wind will blow away the soil. Leaves are no longer present to intercept rain. The soil is washed away. The soil is degraded, over time losing fertility and structure.
  16. 16. Natural Effects of Desertification in the Sahel. <ul><li>Soil erosion- soil washed away so no crops can grow </li></ul><ul><li>Sun baked, cracked soil. </li></ul><ul><li>Loss of plants and animals. (Reduced Biodiversity). </li></ul><ul><li>Dry rivers so even less water </li></ul><ul><li>Increase in sand storms. </li></ul><ul><li>Flash floods </li></ul>
  17. 17. Human effects of Desertification in the Sahel. <ul><li>People cannot find enough water or food for their cattle </li></ul><ul><li>Crops and cattle die </li></ul><ul><li>So the people have no food or water= FAMINE </li></ul><ul><li>Migrants move to cities, resulting in the growth of informal settlements, shanty towns, in already overpopulated urban areas. </li></ul><ul><li>People are forced to leave their own country and take refuge in other countries- they are then known as </li></ul><ul><li>refugees </li></ul>
  18. 18. FAMINE= A extreme lack of food and water for a sustained time period
  19. 19. Stopping it... <ul><li>Plant Trees. </li></ul><ul><li>Roots bind the soil together. Leaves provided shade, and intercept water. </li></ul><ul><li>Cheap, long term. </li></ul><ul><li>Provide fuel wood and building materials. </li></ul>
  20. 20. 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>                                                                                                                                                           
  21. 21. 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>
  22. 22. What can we do? <ul><li>Donate money to charities like Water Aid and Oxfam who can put money towards building wells and putting in irrigation systems </li></ul>Irrigation systems are channels where water can be diverted from wet areas to drought or desertified areas
  24. 24. Task (25mins) <ul><li>Fill in the case study sheet with relevant information </li></ul><ul><li>Write the causes and effects as bullet points! </li></ul>
  25. 25. Task! <ul><li>Exam Question (20 mins) </li></ul><ul><li>What is desertification? (define the term) (2) </li></ul><ul><li>What are the human causes of it? (2) </li></ul><ul><li>What are the natural causes of it? (3) </li></ul><ul><li>Where is it happening? (map needed) Why there? (2) </li></ul><ul><li>What are the effects of it on: </li></ul><ul><li>People, environment and the economy (6) </li></ul><ul><li>6) How are people trying to stop it? (3) </li></ul>Under Exam conditions!