In northernmost Sudan, northerly winds prevail for most of the year, and rainfall is rare. To the south of this the seasons are characterized by the north-south oscillation of the boundary between moist southerly air and dry northerly air. In winter the north winds of the tropical air mass blow

The Nile River system is the dominant physical feature, and all streams and rivers of Sudan drain either into or toward the Nile. It enters the country as the White Nile (Baḥr Al-Abyaḍ) in the southeast, about 60 miles (100 km) south of Kūstī, and maintains an extremely low gradient until it is

Sudan is mainly composed of vast plains and plateaus that are drained by the Nile River and its tributaries. This river system runs from south to north across the entire length of the east-central part of the country. The immense plain of which Sudan is composed is bounded on the west by the Nile

The Natural vegetation: Andrews (1948 ) classified the vegetation of the Sudan,

recognizing seven principal types in a consecutive series from north to south. Ten

years later, Harrison and Jackson (1958 ) produced an ecological classification of the


vegetation recognizing five major