The Sahel is the ecoclimatic and biogeographic zone of transition between the Sahara desert in the North and the Sudanian Savannas in the south. It stretches across the North African continent between the Atlantic Ocean and the Red Sea. The Arabic word sāḥil ساحل literally means “shore, coast”, describing the appearance of the vegetation of the Sahel as a coastline delimiting the sand of the Sahara.
The Sahel covers parts of the territory of (from west to east) Senegal, southern Mauritania, Mali, Burkina Faso, southern Algeria, Niger, northern Nigeria, Chad, Sudan (including Darfur and the southern part of Sudan), northern Ethiopia and Eritrea.
The Sahel is 5,400 km (3,400 mi) from the Atlantic Ocean in the west to the Red Sea in the east, in a belt that varies from several hundred to a thousand kilometers (620 miles) in width, covering an area of 3,053,200 square kilometers (1,178,800 sq mi). It is a transitional ecoregion of semi-arid grasslands, savannas, steppes, and thorn shrublands lying between the wooded Sudanian savanna to the south and the Sahara to the north.
The topography of the Sahel is mainly flat, and the region mostly lies between 200 and 400 meters elevation. Several isolated plateaus and mountain ranges rise from the Sahel, but are designated as separate ecoregions because their flora and fauna are distinct from the surrounding lowlands. Annual rainfall varies from around 200 mm in the north of the Sahel to around 600 mm in the south.
Traditionally, most of the people in the Sahel have been semi-nomads, farming and raising livestock in a system of transhumance, which is probably the most sustainable way of utilizing the Sahel. The difference between the dry north with higher levels of soil-nutrients and the wetter south is utilized so that the herds graze on high quality feed in the North during the wet season, and trek several hundred kilometers down to the south, to graze on more abundant, but less nutritious feed during the dry period. Increased permanent settlement and pastoralism in fertile areas has been the source of conflicts with traditional nomadic herders.
The first instances of domestication of plants for agricultural purposes in Africa occurred in the Sahel region circa 5000 BC, when sorghum and African rice began to be cultivated. Around this time, and in the same region, the small Guinea fowl were domesticated.
Around 4000 BC the climate of the Sahara and the Sahel started to become drier at an exceedingly fast pace. This climate change caused lakes and rivers to shrink rather significantly and caused increasing desertification. This, in turn, decreased the amount of land conducive to settlements and helped to cause migrations of farming communities to the more humid climate of West Africa.
Links and Sources:
- Sahel grapples with food insecurity (csmonitor.com)
- UNICEF: One million children in Sahel countries threatened by famine in 2012 (greenfudge.org)
- Geopolitical experts warn of threats posed by armed violence to security in Sahara, Sahel (moroccotomorrow.org)
- Climate change blamed for dead trees in Africa (wattsupwiththat.com)