Explain the occurrence of drought under the following headings: (a) causes (b) area affected (c) effects (d) control

Occurrence of drought

(a) Causes:

1. Prolonged failure or scarcity of rainfall over a long period.
2. Persistent dry, offshore winds (e.g. the dry, dust-laden North-East Trade Wind / harmattan) that bring no moisture.
3. Deforestation and removal of vegetation, which reduces evapotranspiration and rainfall.
4. Desert encroachment (desertification) and general climate change / global warming.

(b) Area affected: Drought mainly affects arid and semi-arid regions such as the Sahel zone of West Africa (e.g. northern Nigeria, Niger, Chad, Mali), the areas bordering the Sahara, and other dry margins in the Horn of Africa and southern Africa.

(c) Effects:

1. Crop failure and famine due to lack of water for farming, leading to hunger and malnutrition.
2. Death of livestock and loss of grazing land.
3. Drying up of rivers, wells and water bodies, causing acute water shortage.
4. Migration of people and animals, spread of desert conditions and conflict over scarce resources.

(d) Control:

1. Afforestation and shelter belts to check desert advance and improve rainfall.
2. Construction of dams, boreholes and irrigation schemes to store and supply water.
3. Drought-resistant crops and better land management (avoiding overgrazing and bush burning).
4. Public education and provision of relief and early-warning systems.