SAHEL WEATHER AND CROP SITUATION 1999Global Information and Early Warning System on food and agriculture
Report No 5 - 10 October 1999
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After abundant rains in mid or late August in several parts of the Sahel, rainfall decreased somewhat in September but remained generally widespread and above normal. During the first two dekads, rains were well distributed over the producing zones of the Sahel and abundant in Senegal, The Gambia, Guinea Bissau, Burkina Faso and Chad. However, they were more limited in Mali. During the third dekad, they stopped in north-western Senegal and central Chad but continued over all the other producing zones. Cumulative rainfall is generally normal to above normal in Burkina Faso, Chad, The Gambia, Niger and Senegal. High water levels in the Senegal and Niger rivers caused flooding, notably in Mauritania. Soil moisture reserves are adequate except in some areas in northern Senegal and Niger. Early millet and sorghum are maturing or reaching harvest stage in most productive zones. Satellite images for the first dekad of October indicate that cloud coverage continued over most producing zones of Senegal, Mali, Burkina Faso and Chad but diminished over Mauritania, north-eastern Burkina Faso and Niger. Precipitation remained above normal in southern and central Senegal, Mali, western Burkina Faso and southern Chad. Overall, good harvests are anticipated in most countries.
Pastures are abundant and of good quality, notably in Mauritania. Pest infestations (mostly grasshoppers, blister beetles and floral insects) were reported in Cape Verde, Niger, and Senegal. A small outbreak of Desert Locusts occurred in northern Mali as a result of exceptionally good breeding conditions. Limited breeding has also been reported in Mauritania. Elsewhere, no significant developments are expected.
A series of joint FAO/CILSS Crop assessment missions are scheduled in all the
Sahelian countries from 11 to 29 October to estimate 1999 cereal production.
BURKINA FASO CAPE-VERDE CHAD GAMBIA GUINEA-BISSAU
MALI MAURITANIA NIGER SENEGAL
In these reports, reference will be made to four different eco-climatic zones based on the average annual precipitation and agricultural features, i.e. Sahelian zone, Sudano-Sahelian zone, Sudanian zone and Guinean zone. They are shown in the map and described below:
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.