ABSTRACT
The West African region considered within the context of this chapter encompasses area between 15°W to 15°E latitude and 5°N to 25°N longitude. Atlantic Ocean forms the western and southern edge; northern border is roughly the beginning of the Sahara desert coinciding with the upper reaches of river Niger. The eastern edge is generally recognized as the Lake Chad, river Benue, or even eastern border of Nigeria but including small regions in Cameroon. The sixteen countries that occur within the West African zone are Benin, Burkina Faso, Cote de Ivoire, Cape Verde, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo. West Africa occupies about 6,140,000 km2, which is equivalent to 20 percent of total area of African continent. The terrain is undulating with small sandy hills but mostly sandy plains. The highest altitude recorded does not exceed 300 m.a.s.l. However, there are some highland locations such as Fouta Djallon, Guinea Highlands, Sierra Leone Mountains, Nimba Mountains, Jos Plateau, and Plateau of Djado (FAO, 2001). Sahel is a transitional dry zone. It occurs between Sahara in the north and Sudanian-Savannah region in south. Natural and agricultural Savannahs are 160-240 km in breadth and extend from west coast of Senegal to Cameroon in the east.
