HUMAN INTERFERENCE WITH SOILS


Case Study 2: Desertification in the Sahel


Desertification is the spread of desert conditions into new areas, usually following the erosion of exposed topsoil. The world’s worst instance of desertification is happening in the Sahel region of Africa. The Sahel is a narrow zone that runs east–west across Africa at the southern edge of the Sahara Desert (see Figure 4). It occupies large parts of Mali, Chad, Sudan and other countries. Desertification in the Sahel is so bad that desert conditions there are spreading southwards at a rate of 5 to 10 kilometres each year. Human activities have played a major role in this ecological disaster. Rapid population growth is a major root cause of the


problem. Sahelian countries all have high birth rates and declining death rates, which gives rise to rapid population growth in excess of two per cent a year. This has caused many parts of the Sahel to become overpopulated – they contain too many people for the resources available. The increasing population has created a growing need


for resources such as food and fuel. This need has in turn given rise to overgrazing, overcultivation and vegetation clearance.


A large extended family in northern Nigeria. Discuss some causes and effects of high fertility rates in the Sahel.


4


Overpopulation in the Sahel was examined on pages 34–37.


Sahara desert The Sahel Direction of


desert expansion


The Sahel. Name each of the countries labelled Ato G. Consult your atlas or the map on page 34 if necessary


.


189


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