For subcritical flow in an open channel, the control section for gradually varied flow profiles is
(A) at the downstream end
(B) at the upstream end
(C) at both upstream and downstream ends
(D) at any intermediate section
For subcritical flow in an open channel, the control section for gradually varied flow profiles is
(A) at the downstream end
(B) at the upstream end
(C) at both upstream and downstream ends
(D) at any intermediate section