Desertification
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Desertification
What is desertification?
l Desertification occurs where land is turned into desert.
l It occurs mainly in semi-arid lands which border the world’s major deserts.
Which areas are vulnerable?
Vulnerability: Red = very high Orange = high Yellow = moderate
The area of greatest risk: The Sahel
South of the Sahara desert / North of the savanna grasslands
What is The Sahel like?
• Semi-arid area.
• Periods of rainfall and drought.
• Supports small bushes.
• Wind-battered trees.
Physical reasons for desertification in The Sahel
l 1950/60’s - above average rainfall, causing nomadic herders to settle and farmers to intensify agriculture.
l 1970’s - below average rainfall leading to extreme drought. Crops and animals die. Desert advances.
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.
Human reasons for land degradation
l Traditional nomadic tribes settle in one place. Vegetation no longer protects the soil.
l Trees provided protection for the soil, from wind and rain.
l The growing of cash crops, depletes the soil fertility of the area. The soil structure breaks down.
Overgrazing. Cutting down trees. Intensive agriculture.
‘Desertification’ - caused by climate change. ‘Land degradation’ - caused by human activity
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.
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.
Tackling desertification
Plant Trees.
• Roots bind the soil together. Leaves provide shade, and intercept water.
• Cheap, long term.
• Provide fuel wood and building materials.
Tackling desertification
Terracing.
• Prevent rainfall from washing away topsoil and nutrients.
• Cheap to build, only man power needed.
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%.
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