1. Desertification
Desertification
Namib Desert

2. What is desertification?
Desertification occurs where land is turned into desert. Desertification is the intensification or spread of arid conditions.
It occurs mainly in semi-arid lands which border the world’s major deserts.

3. Rate of Desertification
Since the 1970’s there has been a growing body of evidence to show that deserts are increasing in size. Semi-arid areas on the edges of deserts such as the Sahel south of the Sahara have been getting drier and changing into full deserts.
Rate of desertification

4. HOW WIDESPREAD IS DESERTIFICATION?
About one third of the world's land surface is arid or semi-arid. Worldwide, desertification is making approximately 12 million hectares useless for cultivation every year.
Desertification Video 8 mins

5. Which areas are vulnerable?
Vulnerability: Red = very high Orange = high Yellow = moderate

6. The area of greatest risk: The Sahel
South of the Sahara desert / North of the savanna grasslands

7. The Sahel region lies just to the south of the Sahara Desert in Africa.

8. What is The Sahel like? Semi-arid area.
Periods of rainfall and drought.
Supports small bushes.
Windbattered trees.

9. Physical reasons for desertification in The Sahel
1950/60’s - above average rainfall, causing nomadic herders to settle and farmers to intensify agriculture.
1970’s - below average rainfall leading to extreme drought. Crops and animals die. Desert advances.

10. Why does the Sahel suffer from desertification?
Increase in cattle
Increase in population
Deforestation for fire wood
Grassland grazed more intensively
Roots no longer hold soil together
Roots may be eaten as well as grass
Less vegetation means less protection from weather
Leaves no longer protect soil from weather
Loose top soil blown away by wind
(Soil Erosion) =
Loose top soil blown away by wind
(Soil Erosion) =
DESERTIFICATION

11. Causes of desertification
Vegetation roots bind soil.
Vegetation dies.
Soil is left exposed.
No leaves to intercept rain. Soil is washed away.
Wind blows away soil.
Sun bakes the soil and it cracks.
The soil is degraded, losing fertility and structure.

12. How have each of these factors contributed to desertification?

13. Climate Drought: low rainfall since 1968.
Soils become dry and there is no water left in wells.
Trees die, grass withers and is replaced by poor desert scrub.
Crops fail and cattle feed on poor pasture.
Less roots to protect the topsoil, less humus; soils become more sandy and dry.
Wind erosion removes the soil, causing dust storms, leaving bare rock.

14. Human reasons for land degradation
‘Desertification’ - caused by climate change. ‘Land degradation’ - caused by human activity
Overgrazing. Deforestation. Over cultivation (Intensive agriculture).
Traditional nomadic tribes settle in one place. Vegetation no longer protects the soil.
Trees provided protection for the soil, from wind and rain.
The growing of cash crops, depletes the soil fertility of the area. The soil structure breaks down.

16. Human activity Population is high and increasing fast.
To increase food supplies more crops are grown and more cattle kept leading to over-cultivation and over-grazing.
Yields decline and cattle are undernourished and die.
Demand increases for water as population grows.
Trees are cut down for fuel supplies.
Less vegetation; more dry, bare soil; more wind erosion.

18. How does this lead to desert?
Put the following statements into the correct order as a flow diagram.
Vegetation roots bind the soil.
Leaves are no longer present to intercept rain. The soil is washed away.
Sun bakes the soil and it cracks.
Wind will blow away the soil.
The soil is degraded, over time losing fertility and structure.
Vegetation dies.
Soil is left exposed.

20. Animals/insects Locusts destroy the crops.
Overgrazing means all vegetation is eaten.
Animals trample the ground reducing it to dust.
Animals die and can’t breed.

22. Physical impacts of desertification
Soil erosion.
Sun baked, cracked soil.
Loss of plants and animals.
Gullying.
Dry rivers.
Growth of desert.
Increase in sand storms.
Flash floods.

23. Human impacts of desertification
Crops and cattle die, resulting in famine.
Death.
Migrants move to cities, resulting in the growth of informal settlements, shanties, in already massively overpopulated urban areas.

24. http://www. abc. net. au/science/photos/desertification/blank
Effects slideshow
The UN currently estimates that desertification directly affects 46% of land in Africa, and around 250 million people. In Kenya, where desertification and drought has threatened over 11 million with famine.

25. Starvation
Food and water shortages lead to malnutrition, famine, disease and high death rates.

26. Problems?
Civil wars, as in Ethiopia and Sudan prevent aid reaching stricken areas and cause mass migration to refugee camps.
Population growth continues to outstrip food supplies.

27. Aid Programmes
Large numbers of people become dependent on food aid programmes.

28. Migration From rural to urban areas causing over-population in towns.
To refugee camps.

31. How can we solve the problems of desertification?
Solutions?
How can we solve the problems of desertification?

32. Tackling desertification
Plant Trees.
Roots bind the soil together. Leaves provide shade, and intercept water.
Cheap, long term.
Provide fuel wood and building materials.

33. Tackling desertification
Terracing.
Prevent rainfall from washing away topsoil and nutrients.
Cheap to build, only man power needed.

34. Tackling desertification
Magic Stones.
Similar to terracing, stones are placed along contours.
Topsoil can not be washed past the stones. Water infiltrates, instead of running over the surface.
Cheap to build, only man power needed.
Effective, shown to increase yields by 50%.

35. Magic stones Animation!
Part 2

36. Possible Solutions to Desertification
Deforestation - Afforestation, that is re-planting trees. Planting trees can help stabilise the soil and cut down on erosion by wind and rain.
Using good farming practices such as proper crop rotation.
Overgrazing - It is important that the young trees are fenced off to prevent grazing by animals
Terracing the land to slow down the water running off will make better use of the rain that does fall
Most of all desertification can be controlled by human activity.

37. Solutions
In the short-term, provide food aid and water supplies to prevent suffering.
Improve water supplies by building large reservoirs and drilling deeper wells.
Conserve water in local small-scale schemes eg ‘magic stones’ in Burkino Faso.
Encourage sustainable farming practices (using locally-made tools, not tractors).
Provide drought-resistant seed such as millet (northern Nigeria). GM crops.
Tree planting schemes to reduce soil erosion (Mauritania).
International action to reduce the causes of global warming.

39. Your tasks: Desertification in the Sahel
Explain what desertification means.
Draw a sketch map of Africa to show the Sahel.
Name 6 Sahel countries on your map.
Make notes about the causes of desertification - physical and human factors (see pgs Geog Text).
Make notes about ways of managing the land sustainably in the Sahel. Use sub-headings or bullets.