This is the second GIEWS report of the 2001 season on weather and crop conditions in the Sahelian countries of western Africa. Geographical coverage of these reports include the nine CILSS (Permanent Inter-State Committee for Drought Control in the Sahel) member states: Burkina Faso, Cape Verde, Chad, Gambia, Guinea-Bissau, Mali, Mauritania, Niger and Senegal. Reports will be issued each month from June to November. The final report for 2001 with the first production estimates will be issued in late-November
These reports are prepared with data from, and in close collaboration with, out-posted FAO Representatives, the Agro-Meteorology Group and the Environmental Monitoring Group (SDRN), the Emergency Centre for Locust Operations (ECLO), the Special Relief Operations Service (TCOR), the World Food Programme (WFP), as well as various Non-Governmental Organizations (NGOs). In this report, satellite imagery provided by FAO/ARTEMIS, field data on rainfall, FAO agro-meteorological crop monitoring field reports and information provided by FAO Representatives up to 30 June have been utilized. Satellite images of the first week of June have also been utilized for final updating.
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 on 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.
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