Section Four

The spreading desert

Desert Desert is a dry region. It receives less than 250mm of rain a

year.

Climatic characteristics

Rainfall: Less than 250mm rainfall a year. Rainfall is irregular.There may be no rain for several years.

When the rain comes, it occurs in the form of short and heavy thunderstorms.

Temperature: Very hot during the day. Very cold at night. Large diurnal

range of temperature.

Areas in danger of desertification

Major deserts in the world

What is desertification?

Desertification is the process by which the desert spreads into

the surrounding areas.

Five years later

Areas in danger of desertification

Major deserts in the world

Where is the Sahel?

The Sahel

Rainfall and natural vegetation in the Sahel

Desert Grassland and woodland Rainforest

Annualrainfall

Lessthan250mm

250 - 2,000mmMore than2,000 mm

Where is the Sahel? The Sahel is a narrow belt of land in Africa. It is located between the dry desert land to th

e north and the forest areas to the south. Temperatures are always high and there is a l

ong dry season. Most rain comes during the summer. There is

more rain in the south and rainfall decreases towards the desert in the north.

The natural vegetation is mainly grassland.

Soil becomes loose and dry.Land become bare.

Causes of desertification in the Sahel Long period of drought

Soil erosion occurs. Land becomes desert like-land.

Causes of desertification in the Sahel

Long period of drought

Wind Water

As a result . . .

Causes of desertification in the Sahel

Population growth and human activities

demand for food increases

overcultivation overgrazing

Expansion of farmland

Causes of desertification in the Sahel

Population growth and human activities

Overcutting of fuelwood

Causes of desertification in the Sahel Population growth and human activities

Trees cannot grow fast enough to recover themselves.Soil erosion occurs.

Poor irrigation

The soil becomes very salty and crops die.

Causes of desertification in the Sahel Population growth and human activities

Irrigation water bring mineral salts to the surface.Salty soil is not suitable for crop growth.

A summary of the causes of desertification

Drought

Population growth

Overgrazing Expansion of

farmland

Land becomes bare

Soil erosion

Desertification

Overcultivation

Poor irrigation

Overcutting of fuelwood

What are the results of desertification?

Loss of soil fertility andvegetation becomes damaged

Less food production widespread malnutrition

and starvation

Ways to stop desertification in the Sahel

1. Rearing good quality cattle

2. Planting fast-growing grass

4. Large-scale dams to store water for irrigation and HEP

7. Hand dug irrigation canals

5. Growing high-yielding crops

6. Planting fast-growing trees for fuelwood

3. Birth control to reduce birth rates

Problems with the measures to stop desertification

Most Sahelian countries are politically unstable.Civil wars are frequent.It is difficult to carry out development plans.

Birth control has failed. Population pressure remains very high.

The countries in the Sahel are very poor and heavily in debt. Most of the money borrowed has been spent on developing industries and infrastructure.

The government lacks the experts to carry out the development plans. People do not know how to use the new technology.

How can we help?

Desertification is a global problem

Rich countries

Voluntary relief organisations

Individuals

offer financial and technicalhelp to poor countries

such as World Vision and Oxfam provide food and medicine to the local people

donate money and join operations organised by the relief organisations