Climate The Sahel has a tropical semi-arid climate with seasonal variations in rainfall and temperature. It receives 200–600 mm of rainfall a year, most of which falls between May and September (Fig. 26.3). Most of the rain falls in the south; rainfall levels quickly decline as one moves northwards towards the northernmost edge of the Sahel. The rainfall pattern shows great variation from year to year and from decade to decade.
Niamey: precipitation (mm) A-Z
Desertification: The expansion of desert into surrounding areas.
Gullying: Rainwater erodes deep channels into the soil.
extended periods of drought, leading to food shortages and famine;
reduced water levels in rivers and lakes, which impacts on food supplies (e.g. Lake Chad); crop failure, animal deaths, loss of life and forced migration.
During the rainy season, intense run-off causes gullying and soil erosion, which contribute to desertification (Fig. 26.4).
