Great Zab
The length of the Great Zab has been variously estimated at and . Approximately of the river's course are located within Iraq. The average discharge of the Great Zab is per second, but peak discharges of up to per second have been recorded. The average annual discharge is . Because of its torrential nature, Medieval Arab geographers have described the Great Zab – together with the Little Zab – as "demoniacally possessed".