a river in Iran and Iraq, a left tributary of the Tigris. The Little Zab is 456 km long and drains an area of 19,400 sq km; it originates on the eastern slopes of the Kurdistan Range.
In its upper reaches the Little Zab is a mountain stream, and lower down it flows first through hilly and then through flat country. There is spring flooding and low water in summer. The mean flow rate at the point where the river flows into the plain (at Altun Kupri) is 219 cu m per sec, although during the flood season it sometimes increases to 3,000-3,500 cu m per sec. The Little Zab is extensively used for irrigation. At Dukan, Iraq, a hydroengineering complex (a hydroelectric power station with an output of approximately 200 megawatts and a reservoir with a capacity of up to 6.8 billion cu m of water) has been created in a gorge.