  A uniform representation of the mean turbulent velocity profile in the sum of
a wall function and a wake function is applied to an open channel,
quantitatively determining its components. The open channel is thus found to
coherently fit in to the same theoretical picture previously drawn for plane
Couette, plane closed channel and circular pipe flow, and to share with them a
universal law of the wall and a universal logarithmic law with a common value
of von K\'arm\'an's constant.
