The correct conditions for which the hydraulically efficient rectangular channel will deliver maximum discharge are
P – depth of water is equal to half the breadth of channel
Q – depth of water is equal to breadth of channel
R – depth of water is equal to twice the breadth of channel
S – hydraulic radius is equal to half the depth of water
Options:
(A) P and R
(B) P and Q
(C) P and S
(D) R and S
Official Answer Key:
C
Step-by-Step Solution & Explanation
For the hydraulically most efficient (best) rectangular channel section, standard open-channel-hydraulics theory gives: depth y = b/2 (i.e. breadth b = 2y — statement P), and the hydraulic radius R = y/2, i.e. R equals half the depth of flow (statement S). So the correct pair is P and S → option (C). Statements Q and R use the opposite (breadth-to-depth) ratio and are the classic distractors for this well-known result.
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.