Report No 3 - 10 August 1998
The rainy season is now well established in most countries of the Sahel. Following reduced rains in late June, precipitation remained generally widespread in July over most producing areas of Mali, Burkina Faso, Niger and Chad, becoming more abundant and reaching quite northern areas during the last dekad of July. By contrast, precipitation remained limited over Senegal and The Gambia and rains started only in late July in northern Senegal. In Mauritania, sufficient rains after mid-July permitted plantings in the main producing zones. Rains started in Cape Verde in late July. Rainfall decreased in Guinea-Bissau but remained widespread. The latest Meteosat satellite image for the early days of August indicates that clouds remain present over most producing areas of Burkina Faso, Chad, Mali, Mauritania and Niger where precipitation should remain adequate. By contrast, rains remain more limited over Senegal and The Gambia.
Reflecting good rainfall in late July and early August, crops are generally developing satisfactorily in Mali, Burkina Faso, Niger and Chad. Cereals are emerging satisfactorily in Mauritania. In Senegal and The Gambia, crops are severely affected by reduced precipitation. Many plantings failed and improved rains are urgently needed to avoid extensive crop failure.
Grasshoppers are reported in Burkina Faso, Chad, Mali, Niger and Senegal. Grain-eating birds are also present in Mali and Senegal. Limited Desert Locusts activity is reported in Niger. Small-scale breeding is expected with the onset of the summer rains in southern Mauritania, northern Mali, Niger and Chad.
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.