What are the cataracts of the Nile?

Shallow and stretches between Aswan and Khartoum where the water's surface is broken by numerous small boulders and stones that lie on the river bed, as well as many small rocky islets.

This should be right.

The cataracts of the Nile are shallow and stretches between Aswan and Khartoum where the water's surface is broken by numerous small boulders and stones that lie on the river bed, as well as many small rocky islets. This is called "rapids or "white water". River cataracts often go with a rapid down-drop of the river.