Assessment missions have been fielded in drought affected areas of Senegal, The Gambia and Mauritania. Reduced rains in July in the west of the Sahel have severely affected crop development and will diminish yield potential. Abundant rains of late August/early September permitted replenishment of soil moisture reserves, regeneration of pastures and filling of water reservoirs, thus improving prospects for crops that had not failed. Crops are generally growing satisfactorily in the centre and the east of the Sahel.
Grasshoppers are reported in Burkina Faso, Chad, Niger and Senegal. Only isolated Desert Locust adults were reported in southern Mauritania. Numbers are expected to increase as a result of widespread rains in late August and subsequent breeding that may occur during September.
Sahelian zone: Where average annual precipitation ranges between 250 and 500 mm. This zone is at the limit of perennial vegetation. In parts where precipitation is less than 350 mm, only pastures and occasional short-cycle drought-resistant cereal crops are grown; all cropping in this zone is subject to high risk.
Sudano-Sahelian zone: Where average annual precipitation ranges from 500 to 900 mm. In those parts of this zone where precipitation is less than 700 mm, mostly crops with a short growing cycle of 90 days are generally cultivated predominantly sorghum and millet.
Sudanian zone: Where average annual precipitation ranges from 900 to 1 100 mm. In this zone, most cereal crops have a growing cycle of 120 days or more. Most cereals, notably maize, root and cash crops are grown in this zone.
Guinean zone: Where average annual precipitation exceeds 1 100 mm. Guinea-Bissau and a small area of southern Burkina Faso belong to this zone, more suited to root crop cultivation.
Reference will also be made to the Intertropical Convergence Zone (ITCZ), also known by its trace on the earth's surface, called the Intertropical Front. The ITCZ is a quasi-permanent zone between two air masses separating the northern and southern hemisphere trade winds. The ITCZ moves north and south of the equator and usually reaches its most northerly position in July. Its position defines the northern limits of possible precipitation in the Sahel; rain-bearing clouds are generally situated 150-200 km south of the Intertropical Front.