Definition of "streambed"

Thirty feet below her, where the Persians were crashing through the brush, the streambed kinked to the left side of the ravine and ran under an enormous thorn tree with a thick base.

2007 April 1, Thomas Harlan, The Shadow of Ararat: Book One of 'The Oath of Empire'‎, page 294

The easement restricts construction and will keep cattle mostly away from sensitive streambeds.

2007 November 7, Felicity Barringer, “Private Efforts to Preserve the Coast”, in New York Times‎