flash flood

Flash flood on Twenty-five Mile Wash on Hole-in-the-Rock Road. 
Maximum water depth approximately 8 ft. 
Rain causing this flood fell 68 mi to the west west.
(Courtesy USGS DDS21)

A flash flood occurs when river discharge rises rapidly and spills out of the channel. Typical of arid regions where sudden down pours from thunderstorms generate rapid runoff and over bank discharge of small streams. Flash floods rarely last more than a few hours.