river of northeastern Algeria, rising as the Wadi Cherf at the eastern edge of the Sétif plains just east of Aïn Beïda. Meandering north to Guelma, the river turns abruptly east and rushes through a narrow gorge in Mount Nador of the Tell Atlas to Bouchegouf and its confluence with the Wadi Mellah. The Seybouse then bends sharply northward and flows through a tree-lined valley to the Mediterranean Sea, just south of the harbour at Annaba. Except for its estuary, which is plied by small craft in spite of shoals and varying depths, the river is unnavigable along its 145-mile (235-kilometre) length. The Seybouse flows through intensely cultivated country producing grapes and cereals. Irrigation is carried out by channels leading from the main stream directly to the fields.