Sahel: the semi‑arid belt at the southern edge of the Sahara

Climate and physical characteristics

The Sahel has a tropical, semi‑arid climate with high temperatures year round and a short annual rainy season. Typical annual precipitation ranges from about 100 to 600 millimeters, concentrated in a few summer months and highly variable from year to year. Soils are often shallow and nutrient‑poor, vegetation consists mainly of grasses, shrubs and scattered drought‑tolerant trees, and rainfall variability determines the success of crops and pasture. Because of this climatic variability, the Sahel is prone to periodic droughts; notable multi‑year droughts occurred during the late 20th century and had major humanitarian and ecological consequences.

Geography and human geography

Countries that include Sahelian zones typically range from Mauritania, Senegal and Mali in the west through Burkina Faso, Niger, Nigeria and Chad to Sudan and Eritrea in the east. Human populations in the Sahel are diverse, including sedentary farmers, pastoralist herders and urban communities. Livelihoods depend heavily on seasonal rainfall and include rainfed agriculture, livestock grazing and, where available, irrigated cultivation. Population growth combined with changing land use has placed additional pressure on natural resources across the region.

Environmental challenges

The Sahel faces several interrelated environmental problems. Desertification—a process by which fertile land becomes degraded and more desert‑like—is a central concern and results from both climatic trends and human activities. Common local drivers include deforestation for fuelwood, overcultivation that depletes soil nutrients, and overgrazing that removes protective vegetation cover. When topsoil is exposed, wind and episodic heavy rains can cause erosion and further reduce soil productivity. These dynamics also affect important water bodies such as Lake Chad, which has experienced substantial shrinkage in recent decades due to combined climate and human pressures.

Responses, adaptation and restoration

Responses to Sahelian challenges combine local practices, national policies and international initiatives. Techniques that improve resilience include water‑harvesting and small‑scale irrigation (for example drip irrigation), improved and drought‑tolerant crop varieties, agroforestry that integrates trees with crops and livestock, and managed grazing systems that prevent overuse of pasture. Large‑scale restoration efforts, such as the Great Green Wall initiative, aim to restore degraded land and create employment through reforestation and sustainable land management. Early warning systems, better access to veterinary and medical services, land tenure reforms and community‑based resource management are also important parts of the response.

Practical measures and notable facts

Practical measures to reduce land degradation in the Sahel often appear in lists of recommended actions. Typical measures include:

• Regulating grazing and promoting rotational pasture to limit overgrazing.
• Adopting soil conservation methods such as contour bunding and mulching.
• Planting drought‑tolerant trees and practicing agroforestry to stabilize soils.
• Using efficient irrigation and water storage to reduce pressure on surface water.
• Strengthening local institutions and land rights to encourage long‑term stewardship.

For further background reading on the Sahel’s climate, ecology and ongoing initiatives consult regional summaries and project pages: Sahel region overview, geography and countries, climate and rainfall patterns, and desertification resources. Information on demographic and health changes is available at population trends and rural livelihoods. Project and restoration efforts, including soil and water conservation, can be explored via agroforestry programs, soil management initiatives, and regional restoration efforts. For material focused on major water bodies affected by regional change, see Lake Chad studies.