What is the normal depth of a channel in uniform flow?

[Pyrrhus]

I've been reading a bit on open channels. I am wondering in uniform flow (constant Volume flow and constant cross section), the normal height or normal depth of the channel if it is the critical height or depth (when Froude's number is 1). The book doesn't make a relation about it, but i believe it is, because it's the min energy (potential+kinetic) to keep the flow, plus in uniform flow there's no acceleration. What about supercritical and subcritical, i would imagine the inertial forces > gravitational forces in the latter (also because the flow tends to be turbulent), while in the former gravitational forces > inertial forces, right?

 

[Pyrrhus]

Any takers?