Describe desert encroachment under the following headings (a) causes (b) areas liable (c) effect (d) methods of prevention

Desert encroachment (desertification) is the spread of desert-like conditions into once-productive land at the desert margins.

(a) Causes

1. Prolonged drought / declining rainfall at the desert margin (e.g. the Sahel).
2. Overgrazing by too many cattle, sheep and goats, which strips the grass cover.
3. Deforestation and over-cultivation, including bush burning and the cutting of trees for fuelwood, which expose the soil.
4. Population pressure forcing continuous farming without fallow, exhausting and loosening the soil so that wind and water erode it.

(b) Areas liable

• The Sahel belt of Africa south of the Sahara (northern Nigeria, Niger, Chad, Mali, Sudan, Sudan-savanna zone).
• Margins of other great deserts: the fringes of the Kalahari, the Arabian, Thar, Gobi and Australian deserts.
• Generally, semi-arid savanna/steppe lands with low, unreliable rainfall next to hot deserts.

(c) Effects

1. Loss of farmland and fall in crop and animal yields, leading to famine and food shortage.
2. Death of livestock and destruction of vegetation as pasture and water dry up.
3. Migration of people (environmental refugees) away from the affected land, and drying up of wells, rivers and lakes (e.g. shrinking of Lake Chad).
4. Increased soil erosion and dust storms and general impoverishment.

(d) Methods of prevention

1. Afforestation / planting of shelter belts (tree planting) to bind the soil and check the wind (e.g. the Great Green Wall).
2. Controlled grazing by limiting herd sizes and rotating pastures to allow grass to recover.
3. Good farming methods: crop rotation, fallowing, mulching and irrigation to keep the soil covered and productive.
4. Public education and enforcement against bush burning and indiscriminate tree felling, plus provision of alternative fuel to reduce fuelwood cutting.