Desertification

Aim: To understand the effects of drought in countries that have a water deficit.

Skill: To interpret a choropleth map

What is desertification?

Desertification occurs where land is turned into desert.

It occurs mainly in semi-arid lands which border the world’s major deserts.

Describe which areas are vulnerable?

Vulnerability: Red = very high Orange = high Yellow = moderate

The area of greatest risk: The Sahel

Describe the location of the Sahel

What is The Sahel like?

• Semi-arid area.

• Periods of rainfall and drought.

• Supports small bushes.

• Windbattered trees.

Use the choropleth maps

in the back of the atlas to find

out 2 more facts about the Sahel.

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.

Desertification: an animation

With thanks to Staffordshire County Council

Use this flow chart to explain the 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

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.

Overgrazing. Cutting down trees. Intensive agriculture.

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%.