I am not confident of my answer. I have a 2400 gph pump. My 24' stream is only one foot wide and less than 6 inches deep and on a gentle slope that allows for several baby falls. Most of the obvious flow is over the various falls. I assume a wider stream would require a much bigger pump unless you constrict width at various points and even then unless there are little falls, I'm not sure you would see the motion.

If you plan to have your stream running 24/7/ and especially if 365 then you will probably require a pond pump anyway and you would also appreciate the long term energy savings if you had a mag. drive pump over even a regular pond pump.