Question

Which of the followings statements are true about the cut-throat and Parshall flumes.
(A) The cut-throat flume is similar to the Parshall flume, but has no throat section, only converging and diverging sections
(B) It gives nearly as accurate measurements as Parshall flume in free flow condition for smaller throat widths
(C) Angles of convergence and divergence of cut-throat flume changes with size of the flume
(D) Because it is easier to construct and install, the cut-throat flume is often preferred to the Parshall flume
Choose the correct answer from the options given below:

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

Hint:

Remember the main advantage of the Cut-throat flume over the Parshall flume:
It has a flat bottom/floor and no throat section, which makes it much easier and cheaper to construct in the field while maintaining comparable accuracy.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Flumes are hydraulic structures designed to measure the rate of flow in open channels.
The Parshall flume and the Cut-throat flume are two widely used throat-type and throat-less flumes in irrigation water measurement.

Step 2: Detailed Explanation:
Let us evaluate each of the given statements:
- Statement (A): "The cut-throat flume is similar to the Parshall flume, but has no throat section, only converging and diverging sections."
This is correct. The Cut-throat flume was developed specifically to overcome some of the construction difficulties of the Parshall flume.
It has a flat floor and lacks the parallel-walled "throat" section of the Parshall flume. The converging section connects directly to the diverging section (hence the name "cut-throat").
- Statement (B): "It gives nearly as accurate measurements as Parshall flume in free flow condition..."
This is correct. Under free-flow conditions, particularly for smaller flume widths, the accuracy of a Cut-throat flume is comparable to that of a Parshall flume.
- Statement (C): "Angles of convergence and divergence of cut-throat flume changes with size of the flume."
This is incorrect. The angles of convergence and divergence in a Cut-throat flume are held constant across different sizes.
The converging section walls converge at a ratio of 3:1, and the diverging section walls diverge at a ratio of 6:1, regardless of the flume size.
- Statement (D): "Because it is easier to construct and install, the cut-throat flume is often preferred..."
This is correct. The flat floor of the Cut-throat flume makes it significantly easier to construct, install, and align in the field compared to the Parshall flume, which has a drop in the throat floor.
Therefore, statements (A), (B), and (D) are correct, making Option (A) the right choice.

Step 3: Final Answer:
The correct option is (A).