Because the channels are essentially man-made, lacking the natural meanders that help control the speed of most rivers, they downfill as quickly as a flash flood in a canyon ravine and become a danger almost immediately after rain begins to fall.
(they downfill as quickly as a flash flood in a canyon ravine and become a danger; to fall; ) (the natural meanders; help; control the speed of most rivers) Context(the natural meanders help,List([55, 85))):(the natural meanders; help control; the speed of most rivers) (they downfill as quickly as a flash flood in a canyon ravine; become; a danger)
the natural meanders help,List([55, 85))
they downfill as quickly as a flash flood in a canyon ravine and become a danger the natural meanders the natural meanders they downfill as quickly as a flash flood in a canyon ravine
to fall help help control become
control the speed of most rivers
the speed of most rivers
a danger