Great Zab

a river in eastern Turkey and Iraq; left tributary of the Tigris. Length, 473 km; basin area, 26,200 sq km. It rises in the western spurs of the Qutur Range and flows out into the Kurdistan plain. It is fed by mountain snow and rain. High water is in April and May; low water, in summer and autumn. The average discharge at the mouth is about 403 cu m per sec. There is a reservoir. The Great Zab is used for irrigation. The cities of Zibar, Kelek, and Quwair (Iraq) are located along the river.