Question

Consider the following statements about H-flumes used for runoff measurement:

(A) H-flumes are well suited for runoff measurement as they have a high capacity and are accurate at different rates of flow.
(B) They are also well suited where sediment sampling of the runoff is done using automatic silt samplers.
(C) The H-flume is useful for flows ranging from 0.009 to 0.85 cumec.
(D) For smaller and greater flows the dimensions of the H-flume are modified and are known as HS flumes for smaller flows and HL flumes for larger flows.
(E) H-flumes need not require calibration and the rating tables are to be used for measuring discharges.

Choose the correct answer from the options given below:

• A. (A), (B), (C) and (D) only.
• B. (B), (C), (D) and (E) only.
• C. (A), (B), (D) and (E) only
• D. (A), (C), (D) and (E) only.

Hint:

Ask yourself where a rating table comes from in the first place, that alone tells you whether a flume truly skips calibration.

Answer 1

The Correct Option is A

A fast way through this question is to hunt for the one statement that breaks its own logic. Four of the five statements describe genuine, well known properties of H-flumes, wide flow range with good accuracy, sediment friendly shape for automatic samplers, a documented discharge range, and scaled HS or HL versions for flows outside the standard range. None of these contain an internal contradiction.

Statement (E), however, claims no calibration is needed while also saying rating tables are used to read off discharge. A rating table is nothing but the calibrated relationship between the water depth in the flume and the discharge passing through it, someone has to calibrate the flume first to build that table. So saying no calibration needed, just use the rating table cancels itself out, and this statement has to be false.

Removing only the false statement (E) leaves (A), (B), (C) and (D) standing as the correct set.

\[\boxed{\text{(A), (B), (C) and (D) only}}\]